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You are here: BAILII >> Databases >> England and Wales High Court (Patents Court) Decisions >> Zipher Ltd v Markem Systems Ltd & Anor [2008] EWHC 1379 (Pat) (25 June 2008)
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Cite as: [2008] EWHC 1379 (Pat)

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Neutral Citation Number: [2008] EWHC 1379 (Pat)
Claim Nos: HC06 C03919

IN THE HIGH COURT OF JUSTICE
CHANCERY DIVISION
PATENTS COURT

Claim Nos: HC06 C03919
HC07 C01551
HC07 C02890
Royal Courts of Justice
Strand, London, WC2A 2LL
25/06/2008

B e f o r e :

THE HON MR JUSTICE FLOYD
____________________

Between:
ZIPHER LIMITED
Claimant
- and -

(1) MARKEM SYSTEMS LIMITED
(2) MARKEM TECHNOLOGIES LIMITED

Defendants

____________________

Mr Simon Thorley QC, Mr Adrian Speck and Mr Jonathan Hill (instructed by Eversheds LLP) for the Claimant
Mr Richard Arnold QC and Mr Brian Nicholson (instructed by Herbert Smith) for the Defendants
Hearing dates: 17-18, 21-25 April, 6-9 May 2008

____________________

HTML VERSION OF JUDGMENT
____________________

Crown Copyright ©

    Mr Justice Floyd :

  1. This is the latest battle in the sequence of disputes between the Claimant in this action ("Zipher") on the one hand and companies in the Markem group, which includes both the Defendants ("Markem"), on the other. Earlier proceedings concerned the parties' entitlement to inventions disclosed in a number of patents and patent applications applied for by Zipher, including some which are now in issue in this action. The earlier decisions are chronicled in the law reports. Those of HHJ Fysh QC sitting as a deputy High Court Judge are Markem Corp v Zipher Ltd (No 1) [2004] RPC 10, Markem Corp v Zipher Ltd (No 2) [2004] RPC 11 and Markem Corp v Zipher Ltd (No 3) [2005] RPC 3.
  2. HHJ Fysh QC held that Markem Corporation and the Second Defendant were entitled to a number of the wider claims of those patents and applications, but that narrower claims belonged to Zipher. In the course of the proceedings at first instance, Zipher's counsel offered an undertaking to the court as to what it would do with the wider claims if it was successful in establishing its claim to be entitled to them, which at first instance it was not. The Court of Appeal allowed Zipher's appeal: Markem Corp v Zipher Ltd [2005] EWCA Civ 267, [2005] RPC 31. The Court of Appeal took the approach that in the absence of any allegation of breach by Zipher of a private law right, Markem's claim to entitlement could not succeed. The order of the Court of Appeal recited a concession made by Zipher's counsel that some of the wider claims as they stood then were invalid, or (in the case of one claim) invalid if construed in a particular way, but did not recite the undertaking offered to HHJ Fysh QC.
  3. Having secured its claim to ownership of the inventions, Zipher now sues Markem for infringement, claiming that two versions of Markem's SmartDate 5 printer (the EV and LV) and its Series 18 printer infringe:
  4. i) UK Patent No. 2 369 602 ("602");

    ii) European Patent (UK) No. 1 317 345 ("345"); and

    iii) European Patent (UK) No. 1 767 375 ("375").

  5. Markem deny infringement and counterclaim for revocation of each of the three patents sued on, and also for revocation of UK Patent No. 2 400 582 ("582") which is not alleged to be infringed.
  6. Zipher has applied to amend 602. Markem contend that the court should not entertain the application to amend as it is not in conformity with the undertaking given to HHJ Fysh QC. The amendments are opposed by Markem on statutory grounds and because they say the court should not exercise its discretion to allow the amendments even if they are otherwise allowable. This latter point raises the question of whether the court retains (following the entry into force of the Patents Act 2004 on 13th December 2007) any discretion to refuse to allow amendments which would not offend against the grounds of objection under the statute, and, if so, on what principles that discretion is to be exercised.
  7. In all, these disputes give rise to a very large number of issues and sub-issues, which I summarise as follows:
  8. i) Is Zipher's attempt to amend in breach of any undertaking it has given to the court?

    ii) Do Zipher's amendments to 602 add matter?

    iii) Are Zipher's amendments to 602 allowable in the exercise of any discretion retained by the court?

    iv) Are any claims in the four patents in suit invalid for lack of novelty over US Patent Specification No. 4 909 648 ("Datamax")?

    v) Was the information in a Markem document called "the Adkin Memorandum" made available to the public before the priority date of 602?

    vi) If so, do any claims lack novelty over the Adkin Memorandum?

    vii) Are any claims invalid for lack of inventive step over:

    a) Datamax;
    b) The information in the Adkin Memorandum;
    c) US Patent Specification No. 5 490 638 ("IBM");
    d) US Patent Specification No.4 093 149 ("Shroff");
    e) Japanese Patent Application No. S60-211653 ("Ikenaga");
    f) US Patent Specification No. 5 649 672 ("Wolff");
    g) UK Patent Application No. 2 302 523 ("Markem")?

    viii) Are any claims invalid for insufficiency? There are pleaded insufficiencies of three different types: classical insufficiency, Biogen insufficiency and insufficiency through ambiguity.

    ix) Are any claims infringed by any of the three accused models of Markem printer?

  9. In very broad terms the patents in suit are concerned with tape drives for use in printers, tape recorders and similar equipment. Although the claims are wider, the specific embodiments in the patents and the products which the parties make and sell are thermal transfer printers. Thermal transfer printing uses a ribbon with solid thermoplastic ink covering one side. The ink can be melted in specific regions if subjected from the other side to heat from the printing elements in a print head. Once heated, the ink transfers from the tape to the substrate onto which it is desired to print. A major application of this type of printing is in production lines, where it is necessary to add coded information onto a product, such as a "sell by" or "best before" date. For these reasons the machines are sometimes called "date coders" or just "coders".
  10. The witnesses

  11. Zipher called two expert witnesses. The first was Dr Richard McMahon who is a Senior Lecturer in Electrical Engineering in the Department of Engineering at Cambridge University. His professional experience is broad. He has taught and researched the design and application of electrical machines (i.e. motors and generators) and the means of driving and controlling them. He has acknowledged that in the field of computer software he has relied on assistance from elsewhere within the Department.
  12. I thought Dr McMahon was a careful but perhaps sometimes rather reluctant witness. He occasionally, perhaps unnecessarily, preferred to express answers in his own words rather than giving "yes" or "no" replies to propositions put to him. Nevertheless, overall, I found his evidence helpful. Mr Arnold QC, who appeared for Markem with Mr Brian Nicholson, said that Dr McMahon strayed in the course of his evidence into the realm of the advocate. I do not think that was a fair criticism. It is understandable in a dispute of this kind that a witness should wish to express himself in his own words rather than accept unreservedly lengthy propositions put to him. I do not think Dr McMahon was doing more than that.
  13. Zipher's second expert was Mr Michael Nelson who is a Mechanical Design Engineer, with over 40 years experience working on a wide spectrum of engineering projects. For most of the last 30 years, he worked for Cambridge Consultants Limited. He is currently a freelance design engineer. As he explains in his report, when he started his career, mechanical engineers did not necessarily go to university, but often worked an apprenticeship instead. His own apprenticeship was 5 years with Cambridge Scientific Instruments Co. This included one day and one evening a week at the local technical college (which is now Anglia Ruskin University) learning the theoretical and mathematical side of the job. At the end of his apprenticeship he became a skilled Scientific Instrument Maker. Mr Nelson started his involvement with thermal transfer printers in 1995 and continued until 1999. He designed the SmartDate 2c, one of Markem's machines.
  14. Mr Arnold said that Mr Nelson's evidence was only of marginal relevance, for reasons associated with his submissions about the skilled addressee, which I deal with elsewhere. He also faintly suggested that Mr Nelson's connection with Markem and its predecessor meant that he was not truly independent. This second point would only be of substance if I felt that Mr Nelson was influenced in any way by his past association. I formed the view that he was not, and that he was giving his evidence fairly and impartially. He was the only witness with practical experience of designing tape drives.
  15. Markem called Richard Taylor as their only expert. He is an electrical engineer. He worked for EMI Electronics from 1967 to 1975 and then for Quantel, a company involved in the development of digital image processing techniques for the broadcast television industry, from 1975 to 2006. He has no experience of thermal transfer printers, although he has experience of a variety of printing and scanning devices and is familiar with tape drive systems through use.
  16. Mr Taylor fairly recognised that he was not a mechanical engineer. His position as expert for Markem was justified by Mr Arnold on the basis that a specialist mechanical engineer was not a necessary part of the skilled team. Mr Taylor had, in any event, come up in the past with mechanical engineering solutions to problems which were encountered at Quantel (to do with flare in cathode ray tubes). To the extent that specialist mechanical engineering understanding is important, particularly of tape drive design, I think that Mr Nelson was better placed to assist me than Mr Taylor.
  17. Mr Thorley QC, who appeared for Zipher with Mr Adrian Speck and Mr Jonathan Hill, had a further specific criticism of Mr Taylor. This was that he had approached the teaching of the specification in too critical a fashion. At times, when first reading his expert reports, I did feel that Mr Taylor was taking somewhat pernickety points about sentences in the patents. Nevertheless, even if they were not all legally important, they were technically correct. I see no reason not to give weight to Mr Taylor's evidence on this account.
  18. In the end what matters with the experts is the reasoning underlying their opinions. I have no doubt that each of them was doing his best to help me to understand the underlying technology and the basis of the opinions which they have expressed. I also have no doubt that all their opinions were genuinely held.
  19. There were also two factual witnesses from Zipher, Philip Hart and Steve Buckby.
  20. Philip Hart is the Engineering Manager at Zipher. He gave his factual evidence fairly and accurately. Both sides encouraged me to find that he was an entirely reliable witness. I did.
  21. Steve Buckby was a Director of Zipher from 2000 to 2004, when it was sold to Videojet Technologies Limited, but remains a consultant to Zipher. He was responsible for the conduct by Zipher of the entitlement proceedings brought against it by Markem. It was suggested by Mr Arnold that Mr Buckby was not prepared to agree to anything without seeing the very same words in a document. There is some force in this, but there is in the end not much in this case which turns on Mr Buckby's evidence.
  22. Technical background

  23. The following is a summary of the technical background needed for an understanding of the patents and the case. In my judgment all of it would be common general knowledge to the skilled team.
  24. Electric motors

  25. For present purposes two main classes of electric motor are relevant: DC motors and stepper motors. In their simplest form, DC motors work by mounting a rotating armature on a rotating spindle. The armature carries coils of wire which become electromagnets when an electric current is caused to flow in them. Fixed magnets, called the stator, surround the rotating armature. The interaction between the stator and the field generated by the current in the windings of the armature causes the armature to experience a rotational force. As the armature rotates, the current supplied to the windings is caused to reverse in polarity, so that the rotational force remains in the same direction. The reversal of current is called "commutation".
  26. To change the angular velocity and torque exerted by a DC motor one changes the voltage and current supplied. So there is a relationship between the current through the motor and the torque, which can be used to measure and control the torque.
  27. It was well known to measure the precise angular velocity of a DC motor by using a tachogenerator or rotary shaft encoder (which emits a stream of pulses).
  28. Stepper motors

  29. Stepper motors are, as their name suggests, electric motors which move in discrete steps. This stepping is achieved with the use of a stator consisting of multiple electromagnets ("teeth") arranged around a central gear shaped rotor. When current flows in the windings, the teeth of the stator line up with the teeth of the gear shaped rotor. Sequential energising of the teeth under the control of electrical circuitry enables the rotor to move stepwise into alignment with successive teeth of the stator. A diagram of a typical stepper motor looks like this:
  30. Image 1

  31. A stepper motor thus has the advantage that angular position can be precisely controlled through the number of steps through which the motor is required to turn under the influence of the control circuitry. Equally, angular velocity can be easily controlled by controlling the stepping rate.
  32. A stepper motor has the characteristic that, once the stator and rotor teeth are aligned in a particular position, it can hold that position against an external torque, provided that the windings remain energised with enough current.
  33. Dr McMahon's evidence, which I accept, is that in the case of the stepper motor there is no simple equivalent to the straightforward means of measuring torque which is available in the DC motor. This is an important fact relied upon by Zipher in relation to validity.
  34. Back emf

  35. It is well known that mechanically rotating the spindle of a DC motor to cause the windings on the armature to rotate in the permanent magnetic field of the stator causes a back-electromotive force ("back emf") to be generated in the windings. A dynamo or electrical generator works on this principle. Some types of unexcited stepper motors also generate such a back-emf.
  36. If an electrical load is placed across the terminals of a motor, a current will flow which will follow the commutation sequence, and accordingly have a waveform profile. The back-emf from a stepper motor will be pulsed.
  37. Pulse-width modulation

  38. Pulse-width modulation is a technique sometimes used in providing electrical devices with a variable voltage supply. Instead of applying a constant voltage, say 6V, to a device, the device can be supplied with a square-wave voltage which switches between 6V and 0. By varying the periods of 6V and 0V supply, the device can be supplied with voltage which, in average terms, is equivalent to intermediate voltage supplies. This is often much more convenient than using an analogue circuit to knock down the voltage.
  39. When one first switches on the voltage to an electric motor, the inductance in the windings presents a very high impedance. This is because the windings present a large impedance to high frequencies: and the switching of the voltage from zero to full-on is recognised as a high frequency, even if it only represents part of a cycle. To force more current into the windings against this impedance, one has to increase the voltage. But this has the disadvantage that after a short period an excessively high current will start to flow. It is therefore desirable to switch the high voltage off and on again.
  40. Given that circuitry is put in place to vary the supply voltage at start-up in this way, it was common to take the further step of controlling the average current in the windings by varying the on/off ratio of the pulsed supply. This is the width of the pulse to which the term "pulse width modulation" refers.
  41. Filtering and averaging of signals

  42. Monitoring of signals can be made more difficult by the presence in the signal of various types of interference or noise. A DC motor driven from an analogue circuit with a steady voltage will have a steady current in the motor. However, if such a motor is driven from a pulsed supply, the current will consist of a steady component together with a component related to the switching frequency. Consequently in order to monitor the current in the pulsed case, it is necessary to remove the components related to the switching frequency and other noise by filtering.
  43. Filtering is the process of picking out a desired signal from noise.
  44. Averaging is another signal processing function used to smooth out noise and other unwanted signals. Samples can be averaged in several ways. For example one can take 10 samples, add them up, and divide by the number of samples to produce one output value and proceed to the next 10. Alternatively one can apply a sliding window which involves samples 1-10 followed by 2-11 and so on.
  45. Control systems and Proportional-integral-derivative ("PID") control

  46. The simplest form of control for an electric motor is known as 'open loop' control. Open loop control systems assume that sufficiently precise information is known about the characteristics of the motor to enable the desired motor output to be achieved simply by applying the appropriate input conditions. A more sophisticated approach, which does not involve as many assumptions about the motor's characteristics, is a 'closed loop' control system. These systems operate by taking feedback from the output of the motor under control to the controller. This feedback signal is compared with the desired performance to produce an error signal. The input to the plant can then be altered to ensure that the desired performance is achieved.
  47. Proportional-Integral-Derivative ("PID") control is a specific form of closed loop control. The error function is subjected to a proportional function, an integral function and a derivative function. Each of these has a parameter, called the gain, which alters the relative influence of that function. The tuning of these parameters fundamentally defines both the steady state and dynamic performance of the closed loop control system.
  48. The proportional term controls the instantaneous reaction to an error in the desired output.
  49. The integral term is used to stabilise the steady-state error and works by keeping track (by integration) of the history of the errors in the system over time.
  50. The derivative term operates by monitoring the rate of change (i.e. the derivative) of the error signal. When the rate of change is large (indicating a high acceleration or deceleration rate of the motor), the derivative term is used to reduce the power to the motor to damp the system performance, ensuring that oscillations caused by a high proportional gain are reduced and in any event eliminated over time.
  51. Sometimes it will not be necessary or desirable to use all these terms. Hence there are PI controllers, PD controllers and simple P controllers.
  52. Tape drives

  53. A wide range of equipment uses tape driven between spools. Computer tapes, video tapes, cine projectors, typewriters and printers are some examples.
  54. The tape can be driven by motors connected directly to the spools. As anyone who has re-wound a tape recorder or watched a projector knows, the amount of tape wound on or off the spool by one revolution is not the same when the tape is nearly full as when it is nearly empty. To achieve a constant linear tape speed the angular velocities of the spools have to change.
  55. One common way of ensuring constant linear tape speed is by means of a capstan roller which engages the tape directly and drives the tape at a constant speed.
  56. Tension control

  57. A number of systems existed for keeping control of tape tension in a tape drive.
  58. A common way is to provide the supply spool with a drag force. This can be done mechanically with a friction clutch or brake applied to the supply spool. An alternative method is electrical. A DC motor driving a spool may be used as an electrical brake for that spool by powering the motor connected to it to turn in the opposite direction to the turning of the spool. Another method of electrical braking is to use the DC motor so that a back emf will appear at its terminals. If a resistive load is applied to the motor it will exert a drag force on the tape. A controlled drag can be created by varying the resistance applied across the motor terminals.
  59. Tension arm systems

  60. A common component in tape drives is the tension or "dancer" arm. This is illustrated below:
  61. Image 2

  62. This example works by gravity, but the same effect can be achieved with a constant force spring. The idea is to create a length of tape which acts as a buffer in the system, allowing the tension arm to set the tension in the tape.
  63. The tension in the tape is set by the weight of the arm. Subject to a small angular effect due to the fact that the arm does not move vertically up and down, the tension in the tape when the arm is stationary or moving at constant velocity will be half the weight of the arm.
  64. The arm has detectors placed at points before it reaches the extremity of its movement. These detectors can be used to signal the need for more tape to be fed into or withdrawn from the system. The steady-state tension in the tape will remain that set by the dancer arm.
  65. There will, however, be instantaneous changes in the tension in the tape when the tape accelerates or decelerates.
  66. What I have said thus far applies even if the tension arm is operated by a constant rate spring, as opposed to gravity.
  67. It was common ground between the experts that a tension arm could be operated by gravity, by a constant rate spring or by a variable rate spring. Mr Nelson was the witness best placed to deal with this:
  68. Q. ... …it was well known, was it not, that dancer arms, to use your terminology, could be actuated by gravity, by a constant force spring or by a variable force spring?
    A. Yes, I agree with that.

    Tension sensor systems

  69. Pressure transducers may be placed in contact with the tape and used to derive a measure of tension. They operate on the piezo-electric or piezo-resistive principle. They are used in some of the cited prior art documents.
  70. Thermal transfer printing

  71. I have explained the basic nature of thermal transfer printing in paragraph 7 above.
  72. Thermal transfer printers can be operated in two modes: continuous and intermittent. A continuous printer prints on a substrate that moves continuously. The continuous mode requires the printhead to be held stationary and the ribbon to be accelerated to the speed of the substrate. The substrate is printed as it travels past the printhead. In intermittent mode the substrate is stopped. Printing is carried out by moving the printhead along the region to be printed. At the end of printing, the printhead is retracted and moved back to its starting position. The substrate moves on and the ribbon is wound on to the next region available for printing.
  73. The patents in suit

  74. It is convenient to start with 602. It has a priority date of September 2000 and is entitled "Drive Mechanism". My page references are to 602 as proposed to be amended (as found in trial bundle A/3).
  75. The specification makes it clear that its disclosure and its broader claims are not limited to thermal transfer printers, to transfer printers or indeed to printers at all. At page 5 lines 20 to 28 the specification makes this particularly clear:
  76. "The requirements in terms of ribbon acceleration, deceleration, speed and positional accuracy of high speed transfer printers is such that the known drive mechanisms have difficulty delivering acceptable performance with a high degree of reliability. Similar constraints also apply in applications other than high speed printers. Accordingly it is an object of the present invention to provide a tape drive which can be used to deliver printer ribbon in a manner which is capable of meeting the requirements of high speed production lines, although the tape drive of the present invention may of course be used in other applications where similar high performance requirements are demanded."
  77. The initial discussion in the specification does however relate to transfer printers. Having explained the basic structure of a tape drive arrangement with supply and take-up spools, the patentee states at page 1 lines 22-25 that generally
  78. "the known arrangements drive only the spool on to which ribbon is taken up … and rely on some form of "slipping clutch" arrangement on the spool from which ribbon is drawn … to provide a resistive force so as to ensure the ribbon is maintained in tension ….."
  79. The specification goes on to point out (at page 2 lines 1-8) a problem with these slipping clutch arrangements which arises from the fact that the diameter of the tape wound on each spool varies as tape is wound from the supply spool to the take-up spool. If the slipping clutch arrangement which is used to keep the tape in tension applies a constant resistive torque to the supply spool, the tape will have to be pulled harder as the diameter of the spool decreases[1]. This variation in diameter results in an increase in the tension in the tape as the supply spool is progressively unwound. The tension is inversely proportional to the diameter of tape on the spool[2].
  80. There follows a discussion of a number of prior art printers, none of which are cited as prior art in this action. A number of deficiencies of these printers are pointed out, as are differences with the invention.
  81. The specification then goes on (page 5 lines 20-28) to remind the reader of the heavy demands of continuous and intermittent transfer printing in terms of acceleration, deceleration and speed of the tape and the need for positional accuracy. The object of the invention is then spelt out in the terms which I have already quoted in paragraph 57 above.
  82. An important passage comes amidst the consistory clauses for the new claims at page 6 lines 19-27:
  83. "A tape drive in accordance with the present invention relies upon both the motors which drive the two tape spools to drive the tape during tape transport. Thus the two motors operate in push-pull mode. This makes it possible to achieve very high rates of acceleration and deceleration. Tension in the tape being transported is determined by control of the drive motors and therefore is not dependent upon any components which have to contact the tape between the take-up and supply spools. Thus a very simple overall mechanical assembly can be achieved. Given that both motors contribute to tape transport, relatively small and therefore inexpensive and compact motors can be used."
  84. Thus both motors are involved in driving the tape in push-pull mode, and the tension in the tape is controlled by the motors, thus dispensing with the need for additional tape-contacting components. Although "push-pull" is a term which is apparently widely used in this context, it is perhaps not the most technically exact way of describing what is going on, as the supply spool does not push the tape in any meaningful sense. What driving the supply spool achieves is to relieve the load on the take up spool, so that the system can accelerate more easily. The arrangement is similar to a car towing another car by a length of rope, as compared to the towed car having some power of its own.
  85. The patent's suggestion that push-pull mode enables the use of smaller motors was a matter which divided the experts. Whilst there are points in the transfer of the tape from one spool to the other where less power is required (as compared with the single motor arrangement), I prefer the evidence of Mr Taylor that the maximum load condition remains the same. Accordingly the patent's suggestion that smaller motors could be used is incorrect. That this is so would not, I think, be apparent on merely reading the specification: it requires some thought.
  86. The specification goes on to describe an embodiment of a tape drive for a thermal transfer printer. A feature of the embodiment described is that it can function in two directions and operate in both continuous and intermittent mode. At page 14 the specification gives a number of other advantages, which it must be remembered are claimed only for this embodiment:
  87. "The described printer arrangement provides a number of very significant advantages. Firstly, it is possible to use the same apparatus for both continuous and intermittent printing. Conversion of a production line from one form of printing to another does not therefore mean that new printers must be purchased. Secondly, by making relatively minor modifications involving only one additional component (the alternative print head carriages of Figures 10 and 11) the same apparatus can be used for both left hand and right hand applications, using these terms in the sense of Figure 2 (left hand) and Figure 12 (right hand). Thirdly, ribbon replacement is a simple matter given that when in the docked position the print head 4 is automatically pulled back away from the peel roller 33 so as to provide a wide track into which a replacement printer ribbon carried on a cassette can be inserted."
  88. The specification then goes on (by reference to Figures 13 to 16) to describe ways of making more efficient use of printer tape. The details of these do not matter, but what follows from the discussion does:
  89. "The advantages described with references to Figures 13 to 16 can only be achieved if the print ribbon can be positioned relative to the substrate and the print head with great accuracy. The conventional approach to achieving accurate control of tape acceleration, deceleration, speed and position has relied upon a capstan roller positioned between feed and supply spools, but the present invention relies upon a completely different approach, that is the accurate control of the drive applied to the stepper motors … which drive the ribbon spools. The stepper motors operate in push-pull bi-directional mode, that is if the tape is travelling in one direction between the spools both stepper motors are driven in that direction, and conversely when the ribbon is being driven in the opposition direction both stepper motors are driven in that opposite direction. Coordination of the drive to the two stepper motors requires knowledge of the diameters of the spools and this is achieved using the light emitting devices…."
  90. So the demands of the described method of economising on tape (in terms of positional accuracy) are approached from a new angle, namely that of using the motors in a co-ordinated push-pull arrangement.
  91. The required knowledge of the diameters of the spools is described as being achieved with the use of light emitting devices. Ways of doing this are described firstly by reference to Figure 17:
  92. Image 3

  93. A detector 37 mounted on the printhead (itself on a carriage) is moved from right to left or left to right from within the shadow of the spool to the point where it is in the line of sight of an emitter (28, 29). The dimensions are then calculated by trigonometry. The specification continues by explaining that it is necessary also to gather information about changes in spool diameter over time:
  94. "Given knowledge of the spool diameters, the spools can be driven in push-pull mode so as to achieve high rates of acceleration and deceleration by appropriate control of the speeds of rotation of the two stepper motors. Tension in the ribbon between the two spools must however b[e] closely controlled to avoid the tension becoming too high (resulting in over tightening of the ribbon on the spools or even ribbon breakage) or the tension becoming too low (resulting in loss of positional control as a result of the ribbon becoming slack). To avoid this occurring, changes in spool diameters over time are monitored by reference to the stepper motors and tension in the ribbon is directly monitored by reference to the current drawn by the stepper motors."
  95. This passage makes it tolerably clear that the measurement of spool diameters by means of the optical system is an initial measurement or calibration step. Indeed the Figure 17 process is later described as "an initial estimate" of the diameters. The final sentence of the passage quoted above refers to changes in spool diameters being "monitored by reference to the stepper motors" and tension in the tape being "directly monitored by reference to the current drawn by the stepper motors". The impact of these latter passages was the subject of some debate, to which I will have to return.
  96. Having obtained an initial value for the diameters of the spools from the optical system, the specification then describes a further step. The take up motor is used to pull the tape from the supply spool with the supply spool de-energised. The system counts the number of steps taken by the take up spool. The supply spool, being pulled along in this way, functions as a generator and produces a back-emf. Because the motor is a stepper motor, this back-emf will be in the form of a series of pulses. This enables the system to compare the number of steps taken by the take up motor with the number of pulses recorded from the supply motor, so as to arrive at a ratio of the two diameters. This again is in the nature of a calibration process, as opposed to a process carried out during printing, as the supply spool is de-energised, which would not be practical during operation.
  97. The specification then describes a further optical scan of both take up and supply spools in order to determine eccentricities around the circumference. That information is then combined with the information about ratios of diameters from the motors to "give an accurate set of data related to spool diameters and shape". This creates the impression that the exercise is required to be a very accurate one.
  98. The specification then explains the need to calibrate the motors if the current supplied to the motors is to be used for control of tension. It is fair to say that the calibration process is explained in somewhat broad terms. The motors are driven in zero-load conditions at a range of different speeds. The process is said to calculate a motor calibration factor, x for each step rate. A relationship is then expressed:
  99. x = N/V
    where x is the calibration factor for the motor at a given step rate
    V is the average measured motor operation value at the given step rate
    N is a constant normalisation or scaling factor.
  100. This process is said to produce a series of values for x at each of the step rates.
  101. Figure 18 illustrates the calculation of the values of a parameter V, called the motor operation value (not voltage) during calibration.
  102. Image 4

  103. 80 is a regulated power supply. 81 and 82 are first and second motor drive circuits. The current to these motor drives is delivered through series resistors 83 and 85. The potential developed across these resistors by the current supplied to the motor drive circuit is taken via devices 84 and 86, through analog to digital converters 87 and 88 to a controller 89 which delivers pulsed outputs (shown as 90 and 91) to the motor drives 81 and 82.
  104. The above process yields (at the outputs of the ADCs 87 and 88) the values of x and V for each motor at each of the rate steps. Tension is then calculated by the following formulae:
  105. Image 5

  106. It will be seen that the temperature-related function f(T) is eliminated in formula 3. This is based on the expressed assertion that
  107. "temperature variations which will affect the measured values of V1 and V2 will generally affect both motors to the same extent"
  108. This assertion gives rise to an issue of insufficiency.
  109. It is common ground that formula (3) contains a fairly fundamental error, in that it does not take account of the changing angular velocity of the spools. This will result in an error as the spool diameter changes. Correctly expressed, the formula should be
  110. Image 6

    where ω1 and ω2 are the respective angular velocities of the spools.

  111. There is an issue as to whether the skilled person would observe and correct this error, and whether it matters if he or she does not. It is common ground that if the error goes unnoticed, tension control will be compromised to some extent.
  112. The specification explains that tension can be corrected by making a small step adjustment to either or both motors. The control algorithms (an example given is a PID algorithm) are said to calculate an amount of ribbon to be added or subtracted from the path between the spools. It does so when there is an error between the measured tension and a nominal demand tension. The process is described at page 22 line 24-23 line 8 in the following way:
  113. "If the derived value of t is too high (above a predetermined limit), then a small step adjustment can be made to either or both of the motors to add a short section of ribbon to the length of ribbon between the spools. If the derived value of t is too low (below a different predetermined limit), then a short section of ribbon can be removed from the length of ribbon between the spools. The control algorithms used to determine the correction amounts of ribbon added to or removed from the length of ribbon between the spools may be of conventional form, for example the algorithms known as proportional integral derivative control algorithms (PlD control). The algorithms make it possible to compare the measured tension t with predetermined upper and lower limits (the so-called deadband) and, if the measured tension is outside these limits, the difference between the measured tension t and a "nominal demand" tension which is set at a level between the upper and lower limits may be calculated, the result of that calculation being regarded as an error "signal". This error "signal" is then mathematically processed through the PID algorithms, which include a proportional gain constant, as well as integral and derivative factors. The mathematical processing results in a "correction" amount of ribbon that needs to be added to or removed from the ribbon path between the spools during the next ribbon feed. This addition or removal of ribbon maintains ribbon tension within acceptable limits."
  114. A circuit for calculating the ratio of the diameters of the spools is then described by reference to Figure 19 (page 24 and following). As previously trailed, the take up spool pulls the tape off a de-energised supply spool, and the ratio of the steps taken by the two motors is calculated. This, again, is therefore a calibration process even though the specification later incorrectly states that it is appropriate during ribbon usage: see page 26 line 15.
  115. The specification then includes a description of how ribbon tension is monitored using current supplied to the motor drives. This is done by sampling the voltage over resistors 83 and 85 in Figure 18 and preferably when the ribbon is advancing at constant speed. There is some explanation of the need to average the samples over a period of time, sampling frequency, averaging and filtering. There is a major dispute between the experts as to the adequacy of this explanation.
  116. There is a further description (by reference to Figure 20) of an approach to monitoring the change in spool diameters using the area of the spools, working on the assumption that the combined area of the two spools will remain constant. There are some acknowledged errors in this description and the associated formulae on which nothing turns.
  117. Finally I should note that the specification describes an alternative approach to deriving an approximation of ribbon tension is to use the difference in currents drawn by the two motors, as opposed to a ratio as in equation (3).
  118. The 375 Patent

  119. The specification of 375 repeats most of the specification of 602. Much of the material in paragraphs [0022] to [0047] of 375 is however not in 602.
  120. At [0040], the specification explains that printheads used in thermal transfer printing must be accurately positioned relative to a platen (which supports a substrate to be printed) if good quality print is to be produced and that an angular displacement of only a few degrees can radically affect print quality. It goes on to say that the traditional approach to dealing with the problem is to position a printhead on an appropriate support assembly in a nominally corrected position, run a test-print to check the quality, and then mechanically adjust the position of the printhead so as to optimise print quality. It is explained that this requires the installer to make very small mechanical adjustments using, for example, spacers, in a time-consuming fashion
  121. The solution to the identified problem is to mount the printhead on a printhead support assembly which is displaceable relative to the housing in a direction parallel to the print ribbon path by action of a drive mechanism.
  122. The method of operation and benefit of the disclosed apparatus is explained as being that an installer could initially position the printhead so that it would assume a nominal position which would be expected to produce good quality print. A test print run would then be used to assess print quality. The printhead support is then displaced using the drive mechanism and a further print test is run. Adjustments in the position of the printhead are then made by the installer until the print quality is optimised. By using the drive mechanism to displace the printhead horizontally relative to the print roller, there is no need to make mechanical adjustments using, for example, spacers.
  123. Figure 21 provides a more detailed diagram of the arrangement:
  124. Image 7

  125. The important angle is 115, between the printhead and the tangent to the print roller at the point of closest approach to the printhead edge (32). As the relative positions of the printhead and the roller move horizontally, the angle 114 at the centre of the roller between the horizontal and the print head will vary, and that there will be a corresponding change in the angle 115.
  126. The claims

  127. 602 has apparatus and method claims, but Zipher does not assert that any method claim can survive if its corresponding apparatus claim falls. There are three independent apparatus claims 1-3 in 602, all of which Zipher contends are independently valid, along with claim 6 which is dependent thereon. Zipher reserves the right to contend that claim 4 is independently valid if claim 3 is invalid for added matter.
  128. So far as 375 is concerned, claim 1 is the same as claim 1 of 602 as amended. Claim 3 is said to be independently valid but is acknowledged not to be infringed (power monitoring). Its validity is in issue. Only claim 33 of the remaining claims was said to be independently valid.
  129. It is agreed that 582 and 345 do not need to be considered separately as their claims and disclosure are reproduced in 602 and 375.
  130. I set out below the claims of 602 which are really in issue, with added lettering to aid reference. It is convenient to notice that features (a) to (d) are the same for each of claims 1-3:
  131.   Claim 1.
    (a) A tape drive comprising two stepper motors,
    (b) two tape spool supports on which spools of tape may be mounted, each spool being drivable by a respective one of said stepper motors,
    (c) and a controller for controlling the energisation of the motors such that the tape may be transported in at least one direction between spools mounted on the spool supports,
    (d) wherein the controller is operative to energise both motors to drive the spools of tape in the direction of tape transport
    (e) to monitor tension in a tape being transported between spools and to control the motors to maintain the monitored tension between predetermined limits.
      Claim 2.
    (a) A tape drive comprising two stepper motors,
    (b) two tape spool supports on which spools of tape may be mounted, each spool being drivable by a respective one of said stepper motors,
    (c) and a controller for controlling the energisation of the motors such that the tape may be transported in at least one direction between spools mounted on the spool supports,
    (d) wherein the controller is operative to energise both motors to drive the spools of tape in the direction of tape transport
    (e) and the controller is configured to implement a control algorithm to calculate a length of tape to be added or subtracted from a tape extending between the spools in order to maintain tension in the tape between predetermined limits and to control the motors to add or subtract the calculated length of tape to or from the tape extending between the spools.
      Claim 3.
    (a) A tape drive comprising two stepper motors,
    (b) two tape spool supports on which spools of tape may be mounted, each spool being drivable by a respective one of said stepper motors,
    (c) and a controller for controlling the energisation of the motors such that the tape may be transported in at least one direction between spools mounted on the spool supports,
    (d) wherein the controller is operative to energise both motors to drive the spools of tape in the direction of tape transport
    (e) And tension in the tape being transported is determined by control of the stepper motors
      Claim 4
    (a) A tape drive according to claim 3
    (b) wherein the controller is operative to monitor tension in a tape being transported between spools mounted on the spool supports
    (c) and to control the motors to maintain the monitored tension between predetermined limits
      Claim 6.
      (A tape drive according to any preceding claim): incorporated in a thermal transfer printer.

  132. The relevant claims of 375 are the following
  133.   Claim 3.
      A tape drive according to claim 1 or 2 (n.b. claim 1 of '375 is the same as claim 1 of '602 as set out above and claim 2 adds the requirement that the controller be arranged to control the motors to transport tape in both directions), wherein
    (a) means are provided to monitor the power supplied to at least one of the motors (14, 15) and to calculate an estimate of tape tension from the monitored power.
      Claim 33.
      A printing apparatus incorporating a tape drive according to any one of claims 1 to 29, the printing apparatus comprising
    (a) A housing (1),
    (b) a printhead (4) mounted on a printhead support assembly which is displaceable relative to the housing in a direction parallel to a print ribbon path along which a ribbon (6) is driven by the tape drive,
    (c) a first drive mechanism for displacing the printhead support relative to the housing (1),
    (d) a roller (30) which in use supports a substrate (13) to be printed on the side of the ribbon path remote from the print head (4),
    (e) a second drive mechanism for displacing the printhead (4) relative to the printhead support assembly to a printing position in which a portion of the printhead bears against the roller (30) or any substrate or ribbon interposed between the printhead and roller, and
    (f) a controller for adjusting the first drive mechanism to adjust the angular position of the printhead (4) relative to the rotation axis of the roller (30).

    The skilled addressee

  134. The person skilled in the art is the legal construct which the law uses to ascertain the meaning of the language used in the patent as well as to test allegations of novelty, obviousness and insufficiency. He or she is a person with practical knowledge and experience of the field in which the invention is to be applied: Catnic Components Ltd v Hill & Smith Ltd [1982] RPC 183 at 242-243. In a case where the patent calls for a range of skills, the addressee is a team of people who between them have the requisite skills: Minnesota Mining & Manufacturing Co v ATI Atlas Ltd [2001] FSR 31 at [30].
  135. Claims 1-3 of 602 and claims 1-29 of 375 are to tape drives generally. They are not restricted to thermal transfer printers, or indeed restricted to printers at all. It is only more subsidiary claims (claim 6 of 602 and claim 30 of 375) that are limited to thermal transfer printers.
  136. It follows that, when considering the broader claims, the patents are addressed to people with experience of tape drives in fields other than thermal transfer printing.
  137. Markem submitted that the addressee was a person with a degree or equivalent in electrical or electronic engineering. They submitted that there was no need for a specialist mechanical engineer given that courses in electrical and electronic engineering include modules in mechanical engineering. Further, the engineer would have access to someone able to write software. Markem drew a contrast with claim 33 of 375, which they submitted did require a mechanical engineer with experience of thermal transfer printers.
  138. Zipher contends that the addressee was a team comprising a mechanical engineer and an electrical engineer.
  139. I think that there is no doubt that the skilled team here must include a mechanical engineer with experience of designing and building tape drives as well as an electrical or electronic engineer to realise the necessary control systems together with a software engineer. This is what the teams at Markem (for the SmartDate 2) and at Zipher (for the Zodiac) consisted of. It is what the patents in suit require in order to put the invention into effect.
  140. Construction

  141. The correct approach to the construction of the claims of a patent specification is now well settled. The task for the court is to determine what the person skilled in the art would have understood the patentee to have been using the language of the claim to mean: see Kirin Amgen v TKT [2005] RPC 9 [30]-[35]. In that case the list of principles to be found in the judgment of Jacob LJ in Technip France SA's Patent [2004] RPC 46 was approved subject to minor modifications. Pumfrey J (as he was then) listed those modified principles in Halliburton v Smith [2006] RPC 2; [2005] EWHC 1623 at [68] to [69], and added some observations of his own. I apply those principles here.
  142. Construction: "controller is operative ... to monitor tension in a tape being transported"

  143. There are two issues here. Firstly, is the term limited to monitoring actual tension, or will some measure (and if so what sort of measure) of tension do? Secondly, does the monitoring have to happen while the tape is moving?
  144. The first dispute is relevant to validity, because it is suggested that prior arrangements in which a dancer arm signals the approach of the point at which there will be too much or too little tape in the loop will "monitor tension".
  145. It is clear from the specification that the quantity handled by the controller is not a measurement of absolute tension. However, what is attempted to be derived from the formulae is described as a "measure of tension" (see page 2220).
  146. Markem submitted that the phrase was wide enough to cover any system which kept an eye on tension with a view to doing something about it if it went wrong. Zipher submitted that the phrase requires the monitoring of a variable which is in a known relationship to tension or representative of tension at a particular time. That follows, Zipher submitted, because the purpose of monitoring is to establish the movement of the tension from a norm at any time with a view to maintaining the monitored tension within predetermined limits.
  147. I believe Zipher's submission is closer to being correct than Markem's, although I do not accept Zipher's submission in its entirety. Whilst the claim is not limited to monitoring absolute tension, it is I believe concerned with monitoring something which is indicative of tension. It is not, in my judgment, wide enough to encompass keeping an eye on something which simply has some bearing on what might happen to tension in the future if nothing is done about it. I agree with Mr Thorley QC when he says that however far the claim extends in terms of the relationship between the monitored value and the actual tension, it does not extend as far as monitoring something which is not tension at all. I think this is clear from the context of the words in claim 1, because claim 1 goes on to require that the monitored tension is maintained. This does not really work if the notion of tension monitoring is as loose a concept as that for which Markem contend. If what is monitored is not indicative of the tension in the tape, tension is not being monitored in the context of this specification. In essence the claim is concerned with extracting a variable (it may be only a zero or a 1) which is in a known relationship to tension.
  148. However I do not read the purpose of tension monitoring as confined to comparing the monitored value to a norm, although that is clearly one way in which the signal from the monitoring could be used. In my judgment the purpose of tension monitoring in this claim is broader: it is to obtain a monitored signal which can be used in some way to control the motors to maintain the tension.
  149. The second area of dispute surrounds Markem's contention that this phrase means that the controller must be operative to monitor tension whilst the tape is moving. The issue goes to infringement because it is common ground that Markem's accused machines only measure tension when the tape is stationary.
  150. Markem draw attention to the difference in wording with feature 1(c) which only refers to a tape which "may be transported". Markem rely on the fact that the description of the specific embodiment clearly contemplates measurement of tension whilst the tape is moving, and would not work while the tape is stationary, because it relies on the difference in work being performed by the two motors.
  151. Zipher contends that the phrase merely identifies the tape or section of tape which is moved, and does not specify that the tape is moving at the moment that the tension is monitored. Zipher also draw attention to claim 3 which requires the "tension in the tape being transported" to be "determined". Given that tension needs to be determined both when the tape is moving and when it is stationary, Zipher submit that the phrase "being transported" cannot connote only a tape which is in motion.
  152. The specification at page 256-8 says that "preferably the current is detected only during periods in which the ribbon had been advanced at constant speed". This, in context, can only indicate a preference over detecting the current during periods of acceleration or deceleration (rather than a preference over not moving at all). As the embodiment under discussion will not function if the motors are not moving, it would not make sense to say that measurement whilst moving was merely "preferable". In the end, therefore, this passage does not help to resolve the issue of construction except to the extent that it emphasises the fact that in the specific embodiment the tape has to move.
  153. In my judgment Markem's approach to this term is too literal. The invention is concerned with maintaining the tension in the tape generally, not just when it is in motion. So one would expect the same level of generality when it comes to monitoring the tape tension. The skilled person would expect the phrase "being transported" to cover the case where the tape is moving, but not to be limited to it. It would be wrong to construe the phrase in a more limited and literal way just because the specific embodiment relies on the movement of the motors for monitoring tension. The claim does not require the tape to be moving at the moment the tension in the tape is monitored.
  154. Construction: "to control the motors to maintain the monitored tension between predetermined limits"

  155. This feature arises in feature (e) of claim 1. There are similar but not identical features in claims 2 and 3 which I believe it is important to deal with comparatively. Claim 2 requires the motors to be controlled to add or subtract the calculated length of tape (to maintain tension between predetermined limits). Claim 3 requires the tension to be "determined" by control of the motors.
  156. There are, again, two separate points which arise in relation to these features.
  157. Markem contend, firstly, that these features require the controller to be operative to control both motors, not just one of them. They draw a contrast with the reference to "a respective one of said stepper motors" earlier in each claim. This issue goes to infringement, as Markem's machines deal out the adjustment with only one motor.
  158. Zipher contends that so to construe the claims would be in conflict with page 22 lines 21-23 of the specification:
  159. "then a small step adjustment can be made to either or both of the motors ….."
  160. Markem respond by pointing out that the specification then goes on to emphasise the advantage of sharing the adjustment between the two motors. Thus, they contend, the skilled reader would see when he comes to the claim that the patentee is deliberately using language to limit his invention to the case where the adjustment is shared between the motors.
  161. I reject Markem's contentions on this issue. In my judgment, the language of the claims is apt to cover the case where all the adjustment is given to one of the motors as well as the case where it is shared. There is no requirement that the adjustment should always be shared. This conclusion applies to each of claims 1 to 3.
  162. The second point which arises on this feature is as follows. Markem contended in their opening skeleton at paragraph 142 that these features require the tension to be maintained solely by the use of the stepper motors. They relied on the passage in the description which I have already referred to:
  163. "Tension in the tape being transported is determined by control of the drive motors and therefore is not dependent on any components which have to contact the tape between the take-up and supply spools" .

  164. Markem developed this point in their final submissions as follows. In claim 3 the tension in the tape is "determined by" control of the motors. This, they submitted, meant that it was the motors (and nothing else) which determined the tension in the sense of both monitoring it and setting it. Reading claim 1 purposively and in context, the monitoring and maintaining requirements of claim 1 were to be read in the same sense as claim 3, so that it is the use of the motors and the motors alone which monitors the tension and maintains it within the limits.
  165. Zipher contended in its oral opening that the claim was apt to cover the situation where the motors are a means of maintaining tension, even if they are not the sole means: see Day 1 pages 57-58. By the time of its closing written submissions at paragraph 164 Zipher stated that it accepted the point made in paragraph 142 of Markem's opening skeleton, that the control of the motors alone must maintain the tension. Nevertheless it submits that this phrase does not exclude the presence of equipment to monitor tension between the spools.
  166. The parties are divided as to whether the description at page 6, which speaks of the avoidance of intermediate components which contact the tape between the spools, is describing an advantage obtainable with the invention or one inevitably obtained by following the claims. For my part I do not think it is sufficiently clear for the skilled reader to take it as read that avoidance of intermediate components is an essential feature of all the independent claims. So the reader is reliant on the language of the claim to understand what is meant in each case.
  167. I start with claim 3, which requires that the tension is "determined by control of the stepper motors". The word "determined" hints strongly at the negative proposition that the tension is not controlled by anything else: it is set by the motors. The passage on page 6 regards it as a consequence of the motor control determining tension that there are no intervening tension-controlling components ("and therefore").
  168. By contrast I do not think that the requirement that control of the motors determines the tension would convey to the skilled person the additional idea that it is the use of the motors which monitors tension. It is true, as Mr Arnold submits, that the striking feature of the specific embodiment is that, in addition to driving the motors to set the tension in push-pull mode, the current supplied to the motors is used to monitor the tension. Whilst both concepts are essential, their functions are explained separately in the specification. In my judgment, the skilled reader would not understand the monitoring function to be encompassed by the phrase "tension … is determined by control of the stepper motors". I think the claim is entirely non-specific as to how (or indeed if) tension is monitored.
  169. It follows, in my judgment, that claim 3 only excludes the presence of additional tension-controlling devices as opposed to monitoring devices. The motors are not required to monitor tension, only to control it. Tension monitoring is introduced into claim 3 by claim 4, without any limitation as to how or where it is done.
  170. It is not easy to reach the same conclusion in relation to claim 1. The requirement that the motors are controlled to maintain the monitored tension between predetermined limits is different from the requirement that they are controlled to determine the tension in the tape. It does not seem to me that this phrase excludes the presence of other things which may be helping to maintain the tension in the tape. Of course if the motors cannot influence the tension in the tape, because tension is maintained wholly by other means, then the requirement is not satisfied.
  171. Claim 2 is different again. The control required of the motors is only to add or subtract lengths of tape (the lengths having been calculated to be such as to maintain tension between predetermined limits). I am equally unable to read any negative restriction so as to exclude other tension controlling devices into this claim.
  172. Construction: Predetermined limits

  173. Feature (e) of claim 1 again requires that the controller is operative "to control the motors to maintain the monitored tension between predetermined limits". The phrase "predetermined limits" also occurs in feature (e) of claim 2.
  174. Markem contend that, if the phrase is not to give rise to fatal ambiguity, it must be construed to mean "within acceptable limits: i.e. normal operating limits for the application concerned", and Zipher does not really disagree. I see no reason not to adopt this construction.
  175. Construction: control algorithm to calculate a length of tape

  176. This feature occurs in claim 2 of 602, at feature (e). Markem contend that the term "control algorithm" gives rise to issues of insufficiency, as it is unclear. I will deal with that issue under that heading. There is a further issue as to what is meant by "calculate a length of tape".
  177. Markem say that the feature can be construed literally to mean that the system performs a calculation of the length of tape; or alternatively it can be construed so as to mean that the system ensures that sufficient tape is added or removed to adjust the tension. They prefer the literal construction, on which basis they say they do not infringe.
  178. Zipher says that the algorithm must be such as to calculate a measure or quantity which represents the amount of tape which needs to be added or subtracted. That measure is then converted into motor steps which are to be applied to either or both motors.
  179. I favour Zipher's construction. The expression clearly covers a system where there is a calculation in units of length of the amount of tape to be added or subtracted; but it is not limited to that. The claim will cover any control system which calculates a tension-controlling amount of tape.
  180. Construction - "Controller"

  181. This phrase arises in feature (f) of claim 33 of 375.
  182. Markem contend that the expression only encompasses a basic form of control which allows the installation operator manually to displace the printhead on the carriage to carry out the adjustment process.
  183. Zipher contends that it is a means which drives the printhead laterally, operated by the operator, and which controls the way in which the carriage moves such as to meet the needs of moving the printhead to make changes in the angle 115.
  184. The real issue is whether the claim is limited to manual operation. I cannot so read it. I cannot see any reason why the skilled reader would treat other ways of controlling the position of the printhead as excluded by the word "controller".
  185. Construction "angular position"

  186. The controller has to adjust the angular position of the printhead relative to the rotation axis of the roller. Whilst the language of the claim is not really apt to say this, it is clear that the angle in question would be understood from the specification as a whole to be the angle 115 in Figure 21.
  187. Zipher's application to amend 602

  188. There is no dispute that the claims in 602 sought by Zipher by way of amendment and relied on for the purposes of infringement are broader than claim 5 of the application in the form it was in at the trial of the entitlement proceedings. Logically, the first question to consider is whether the present application to amend is in breach of any undertaking binding on Zipher. If so then it would follow that the amendments cannot be allowed. If the amendments are not allowed, there is no claim alleged to be infringed in the 602 patent which is not conceded to be invalid.
  189. The Undertaking Point

    Facts

  190. Claim 5 of the application as filed and published included the requirement that
  191. "means are provided to monitor the power supplied to at least one of the motors and to calculate an estimate of tape tension from the monitored power."
  192. Claims 1 to 3 were very much wider. Claims 1-3 were similar to, but wider than, features (a) to (d) of the proposed amended claims set forth above. Claim 4 was effectively the monitoring and controlling feature of claim 1(e) in the amended claim.
  193. Zipher's case before HHJ Fysh QC and the Court of Appeal was that Mr McNestry, its own employee, had invented the subject matter of claim 5 after he had left Markem. During the course of filing and prosecution of the claims, its patent attorneys had broadened out Mr McNestry's idea, and in the course of doing so had accidentally laid claim to subject matter which had been discussed at Markem.
  194. In the course of closing speeches at the trial, HHJ Fysh expressed concern at the possibility that, if Zipher retained claims 1-4, Zipher would assert those claims against Markem. This led to the following set of exchanges between the judge and counsel for Zipher, Mr Adrian Speck:
  195. THE JUDGE: Yes, sorry, claim 1 -- then broadening up to claim 1 they are going to cover something he says that was invented at Markems.
    MR. SPECK: That is the problem and that is why we have made it quite [clear?] again and again that if my Lord thinks our claim is too broad we would be prepared to go back to the narrow ones.
    THE JUDGE: He will probably say that if I leave you with broad claim you will try and close him down on that bit.
    MR. SPECK: No, he will not.
    MR. SPECK: My Lord, I have made our position plain on that. If my Lord thinks we should go back to four or five then we will go back.
    [THE JUDGE] There may be other procedural eventualities. However, we are leadenly clubbing it out.
    MR. SPECK: No, we are not. I have made it absolutely plain. Our inventor thinks claim 5 is the crucial, the clever bit. We would be more than happy to drop down to claim 5 if my Lord thinks that the claim is too wide. The difficulty is that validity and so forth is not directly a matter for these proceedings but we can see the sense in my Lord taking a view on that and saying we are entitled to claim 5 in the subsidiary claims and we keep a patent as it stands on that. We have always made our position clear.
    THE JUDGE: I can see they will turn around and shut you down. Then if I let you get on with the broad claims you will have a go at them.
    MR. SPECK: No.
    THE JUDGE: There is an undertaking coming.
    MR. SPECK: I have already made that plain. What would we have a go at them with on the broad claims? There is no evidence they want to do Adkin, there is absolutely nothing that we can have a go at them on. What does my Lord have in mind because there is nothing?
    THE JUDGE: In the way of a commercial product at the moment.
    MR. SPECK: No. This is completely contrived. There is no suggestion that they want to do whatever it is they say is shown in Adkin. My Lord must appreciate that.
    THE JUDGE: All right.
    MR. SPECK: I am not standing here wanting to get away with claim 1 so that I can have a go at them. I am defending an application by Markem whereby they claim to be entitled to my patent and that claim. I would hardly be saying to my Lord that we would be perfectly happy with claim 5 if that was my aim. My Lord, appreciates ---- There is one thing that those behind me are very anxious that my Lord appreciates, and that is this point about the width of the ribbon drive claims. Again, I repeat, if my Lord thinks they are too wide and I can quite see how my Lord would say, that we would be perfectly happy to give an undertaking to my Lord, as I indicated in opening -- this is only an application so it is easily done on that one -- we could give an undertaking not to prosecute the wider claims. We can come back to either claim 4 or 5.
    THE JUDGE: Why do you not do it any way, out of an abundance of caution?
    MR. SPECK: I will just take some instructions.
  196. Mr Speck took instructions overnight. On day 8 a sheet of paper was handed in which showed claim 5 incorporated into claims 1 and 4. Mr Speck returned to the topic in this way:
  197. MR. SPECK: My Lord will recall me asking about claims 1-4, the ribbon drive, yesterday.
    THE JUDGE: You have had an opportunity ----
    MR. SPECK: I have. I am in a position to accept my Lord's invitation out of an abundance of caution.
    THE JUDGE: It was a suggestion.
    MR. SPECK: My Lord's suggestion, that out of an abundance of caution we would undertake to my Lord not to prosecute a claim over and above claim 5 (which is actually claim 1) plus claim 4, plus claim 5; all the integers are put together. My learned friend complained that he wanted it written down on a piece of paper. We have done so, although it is straightforward ----
    …MR. SPECK: We have set it out on this piece of paper in the three sections, so one can see where the wording comes from. The top is claim 1, the middle bit is the wording from claim 5, obviously one takes out the words, "a tape drive according to claims, 1, 2 or 3" and we just have the "wherein". Likewise, on claim 5 "wherein" is the bottom part of this piece of paper. We will, out of an abundance of caution, give my Lord an undertaking. We are concerned on our side to repeat that it is rather concerning yesterday that my Lord thought these wider claims could be asserted against a commercial embodiment of Markem's. There is absolutely no evidence that they have -- for instance, that they are doing the Adkin machine, so ----
    14 THE JUDGE: Yes.
    MR. SPECK: Perhaps, or that they even want to do that. That is not as we have perceived the evidence at the moment; contrary for our position ----
    THE JUDGE: Mr. Speck, that is fine. It is just that, being a judge, I see in every case hidden agendas, or rather I do not see them but I feel hidden agendas.
    MR. SPECK: It is something that my Lord said yesterday which made it look as though you thought that both of us were trying to assert these claims against each other after judgment.
    THE JUDGE: It is certainly true one way, or the possibility ---
    MR. SPECK: It certainly is, but we say not the other.
  198. Further clarification of the nature of the undertaking was offered as follows:
  199. MR. SPECK: My friend has asked me to clarify the nature of the offer and there was another point which occurred to me when we were looking at the claims. Of course our offer to narrow the apparatus claim will be mirrored in the method claim which my Lord has just seen.
    THE JUDGE: Yes, the one tagged at the end.
    MR. SPECK: Yes, so that covers both. I just wanted to make that plain. The other point is that this is an unconditional offer made to you, my Lord, to the court; it is not subject to my friend accepting it. That is what we will do to the claims should we succeed and we maintain our patent in our name. It is obviously subject to my friend's argument that it is not open to us to throw the swag in the river, as he puts it. Apart from that we will do it if we successfully maintain the patent in our name. It is not an offer to my friend to accept or reject in that way, it is an offer that we make to the court. (emphasis supplied)
    THE JUDGE: If you are successful.
    MR. SPECK: Absolutely. My friend has asked me to clarify that. If the patent remains in our name we will narrow claim 1 to introduce ----
    THE JUDGE: I [had] rather understood that. I think we have to go on. I do not think there is any possibility of ----
    MR. SPECK: He is not going to accept it.
    THE JUDGE: No. Then do not let us waste time on it. I have your undertaking.
  200. In his judgment [2004] RPC 10 at [134] HHJ Fysh QC recorded Zipher's position as follows:
  201. "In relation to claims 1-4, I am of the view that their subject matter had been devised by one or more of the named inventors at MTL. I say this for essentially the same reasons as I have given for '326. It was in respect of this application that during closing speeches, Mr Speck unconditionally offered to limit claim 1. His proposal was to combine existing claims 1, 4 and 5 ('the clever bit') so as to create a new claim 1 leaving claims 2 and 3 still subsidiary to it. The development did not attract Mr Watson but for reasons which will become apparent, it was, I believe, a realistic response to the evidence. "
  202. It will be noted that HHJ Fysh QC said Mr Speck "unconditionally offered to limit claim 1". I believe that accurately records what the transcript shows. It is implicit that Zipher would only be able to limit claim 1 if they retained claims 1-4 in their name.
  203. HHJ Fysh QC gave effect to his judgment that Claims 1-4 of the 602 application as it then stood belonged to Markem by ordering that the application be assigned to Markem with certain claims deleted and that Zipher file a divisional application directed to the deleted claims.
  204. In the light of the learned Judge's finding that Markem owned claims 1-4, the undertaking was academic and it was accordingly not recorded in the Judge's order.
  205. Zipher's skeleton argument on the appeal from HHJ Fysh's judgment included the following:
  206. "179. The learned Judge should have rejected Markem's claim to entitlement to those claims and accepted Zipher's offer to drop them from the application by amending down to claim 5.
    214. Zipher's appeal should be allowed. Claims 1 to 4 of Ribbon Drive (602) are not derived from anything done at Markem. Zipher are willing to delete them and confine its claims to claim 5…."
  207. During the hearing of the appeal Zipher stated through its counsel that it did not resile from its position below. Mr Thorley QC (who by then represented Zipher) said:
  208. "The question that arises of course is if you divine an inventive concept and then you find that certain claims have gone way beyond it, that may be a circumstance when you, the comptroller, say those claims must go. That is what I am coming down to. We made an offer down below that claims 1 to 4 should be deleted. That was our submission, and that is not something I resile from."

    In this passage, the reference is to an offer, but later on Mr Thorley QC described it as an undertaking that was given:

    "The fact that we now accept, having gone through Datamax, that there may be no validity in claims 1 to 3, and we have accepted claim 4 can go as well because claim 5 is really what circumscribes what we want is neither here nor there, that undertaking was given below and it remains."
  209. The Court of Appeal held that Markem were not entitled to any part of 602. One ground on which they so held was that a claim to entitlement must be based on breach of some private law right, a proposition on which the House of Lords subsequently took a different view: see Yeda Research v Rhone Poulenc Rorer [2007] UKHL 43. Markem contend that, whatever the legal basis, the eventuality upon which the undertaking offered to HHJ Fysh QC was to take effect had now arisen.
  210. Following the judgment in the Court of Appeal there was a further hearing to decide the form of order. Markem sought the inclusion in the order of an undertaking somewhat wider than that which had been proffered to HHJ Fysh QC. The Court of Appeal declined to require Zipher to give this undertaking or require any undertaking to be recorded in its order. It did require that the order should record the concessions made by Mr Thorley about the validity of claims 1-3, and claim 4 on the basis of a particular construction of that claim. That is what the Court of Appeal's order ultimately recorded
  211. In the course of the argument before the Court of Appeal, Jacob LJ said to Mr Watson QC who then appeared for Markem:
  212. "actually what we have held is that it [i.e. 602] is his [i.e. Zipher's] patent application, it is no business of yours and that is the end of it. The concession by Mr Thorley is really a concession by Mr Thorley and no more."
  213. There had of course been more than a concession about validity. There had been an undertaking to the court below. The distinction is crucial here, where Zipher seeks to create claims wider than claim 5 but not as wide as the admittedly invalid ones.
  214. The rival submissions

  215. Markem summarise the position in this way:
  216. "…Zipher voluntarily, upon competent professional advice, after taking time for reflection and with a view to securing a tactical advantage in the entitlement proceedings, gave a binding undertaking to the Court to amend '602A down to Claim 5 from which it has never sought to be released and never has been released."
  217. Zipher summarise their position in this way:
  218. ".. [n]o undertaking was ever given and accepted by the Court. There was just a proposal which was not accepted by HHJ Fysh QC as the appropriate way to go. Before the Court of Appeal the whole foundation for any such undertaking fell away by the decision on the main issue of the correct approach to entitlement and Zipher's complete victory on that issue. That is why no undertaking appears in any Order."

    Discussion

  219. There is obviously a difference between giving an undertaking and offering one. Every party who applies for an interim injunction impliedly offers a cross-undertaking in damages. He does not give it if the court declines to grant the injunction. It is then no longer material to the court's decision. If, on the other hand, an order for an injunction is to be made, the court accepts the offer. If the successful party were to make it plain that he refuses or is unable to give the cross undertaking, the court may – probably will - refuse to grant the injunction.
  220. In other circumstances an undertaking is both offered and given at the same time. If counsel says to the court "You have my undertaking to do X within 7 days" that undertaking takes effect immediately. It means "This is what I will do". It bites unless it is discharged. It does not have to be recorded in an order, although it is preferable that it should. If a party does not comply with an undertaking it is the undertaking which is enforced, not the order: see Hussain v Hussain [1986] 1 Fam 134. Every practitioner knows that the giving of an undertaking to the court is a most serious step. It is only ever done on clear instructions.
  221. I think the distinction which I have drawn is critical to deciding the present issue. Was Zipher making a proposal as to what it would be prepared to offer if the court decided in its favour, and which they could withdraw at any stage? Or was Zipher saying "This is what Zipher will do to the claims of the patent if it obtains them"?
  222. I think it is clear that Zipher was doing the latter rather than the former. I explain my reasons below.
  223. Some of the discussion on Day 7 of the trial made reference to a possible finding by the Judge that the claims were "too wide". This could have been the basis for a conditional undertaking which would have depended on the court coming to the conclusion that the claims were too wide. But on Day 8, when the matter was revisited, the undertaking was proffered without any such condition. Indeed it was said to be unconditional.
  224. Thus when Mr Speck said "This is what we will do should we succeed and maintain our patent in our name" he was not qualifying it any further. Importantly he was not saying that this is what Zipher would do if the court should consider it material or if the court wishes to accept it or should it be the High Court which awards us the patent but not if the Court of Appeal does the same thing.
  225. It is absolutely clear that what was being said was that Zipher would amend down to a claim no wider than claim 5.
  226. Zipher attaches very great significance to the fact that the undertaking is not recorded in the court's order. I do not think it is at all surprising that it was not. The undertaking was only to bite if the court awarded claims 1-4 to Zipher, which it did not. It would have made little sense to record the undertaking in an order which awarded claims 1-4 to Markem. The way in which that was to be carried out was as I have described above. The absence from the order is in my judgment no support for the idea that the undertaking was not given. The place to look to see whether the undertaking was given is the transcript which records it being given, not the order which does not need to. Even if the court had awarded claims 1-4 to Zipher, the enforceability of the undertaking would not have depended on whether the undertaking was recorded in the order.
  227. HHJ Fysh QC correctly recorded that "Mr Speck unconditionally offered to limit claim 1." His subsequent reference to it as a proposal is, I think, in connection with the fact that Markem did not accept it as a compromise of their claim to claims 1-4. But Mr Speck had made it clear that the undertaking was in no sense conditional on acceptance by Markem.
  228. I think that what happened after the trial is irrelevant unless it amounted to discharging Zipher from its undertaking to HHJ Fysh QC. In my judgment, nothing that happened thereafter had that effect. Indeed, Mr Thorley based his oral argument at this trial on the proposition that no undertaking had been given to and accepted by HHJ Fysh QC (for which his principal support was its absence from the order) rather than on the proposition that an undertaking had been given and discharged.
  229. Zipher's arguments on the substantive appeal to the Court of Appeal made it clear that it was not seeking to disturb the position from that which had pertained below: Indeed it sought to reinforce the impression that claim 5 was as far as they would and could go: "That undertaking was given below and remains". Although Zipher resisted the incorporation of an undertaking into the order of the Court of Appeal, it never applied to be discharged from the one it had already given.
  230. I do not think it makes any difference that the Court of Appeal decided the claim to entitlement on a different basis. As I have held, the undertaking was not conditional on the particular basis on which the court awarded the claims to Zipher. It was unconditional.
  231. The fact that Markem sought to have an undertaking recorded in the Court of Appeal's order was relied on heavily by Mr Thorley. He asked, forensically, why Markem would seek such an undertaking if it already had the benefit of the undertaking from the court below. There are, I think, two answers. Firstly, it would be preferable for the undertaking, now that it had bitten, to be recorded in an order of the court. Secondly, the wording of the undertaking was slightly wider than that which had already been given to HHJ Fysh. It was not therefore inconsistent for Markem to ask to have an undertaking recorded.
  232. In the result I would hold that Zipher is precluded by its unconditional undertaking to this court from making amendments to 602 which have as their result claims which are wider than claim 5 of the application.
  233. The result is that the application to amend must fail as all the claims which result from the application are wider than claim 5 in the application as filed. The action for infringement of 602 must fail as well, as all the claims which are alleged to be infringed are wider than claim 5 of the application.
  234. Markem ask for an injunction to enforce the undertaking. I will hear counsel in due course on whether such a remedy is necessary.
  235. Nevertheless, in case the matter goes further, I must go on to make findings on all the further issues raised by the amendments, and by the action.
  236. Added Matter

    Law

  237. Section 76(3)(a) of the 1977 Act provides that an amendment is not permissible if it would result in the patent disclosing additional matter. What this involves was summarised by Jacob J (as he was then) in Richardson Vicks' Patent [1995] RPC 568 at 576:
  238. "I think the test of added matter is whether a skilled man would, upon looking at the amended specification, learn anything about the invention which he could not learn from the unamended specification"
  239. Kitchin J's summary of the law in the following passage in his judgment in European Central Bank v Document Security Systems Inc [2007] EWHC 600 (Pat) was endorsed by the Court of Appeal in Vector Corp v Glatt Air Techniques Ltd [2007] EWCA Civ 805, [2008] RPC 10 at [7] and again in European Central Bank v Document Security Systems Inc [2008] EWCA Civ 192 at [12]:
  240. "96. The test for added matter was explained by Aldous J in Bonzel v Intervention Ltd [1991] RPC 553 at 574:
    'The decision as to whether there was an extension of disclosure must be made on a comparison of the two documents read through the eyes of a skilled addressee. The task of the Court is threefold:
    (a) To ascertain through the eyes of the skilled addressee what is disclosed, both explicitly and implicitly in the application.
    (b) To do the same in respect of the patent as granted.
    (c) To compare the two disclosures and decide whether any subject matter relevant to the invention has been added whether by deletion or addition.
    The comparison is strict in the sense that subject matter will be added unless such matter is clearly and unambiguously disclosed in the application either explicitly or implicitly.'
    97. A number of points emerge from this formulation which have a particular bearing on the present case and merit a little elaboration. First, it requires the court to construe both the original application and specification to determine what they disclose. For this purpose the claims form part of the disclosure (s.130(3) of the Act), though clearly not everything which falls within the scope of the claims is necessarily disclosed.
    98. Second, it is the court which must carry out the exercise and it must do so through the eyes of the skilled addressee. Such a person will approach the documents with the benefit of the common general knowledge.
    99. Third, the two disclosures must be compared to see whether any subject matter relevant to the invention has been added. This comparison is a strict one. Subject matter will be added unless it is clearly and unambiguously disclosed in the application as filed.
    100. Fourth, it is appropriate to consider what has been disclosed both expressly and implicitly. Thus the addition of a reference to that which the skilled person would take for granted does not matter: DSM NV's Patent [2001] RPC 25 at [195]-[202]. On the other hand, it is to be emphasised that this is not an obviousness test. A patentee is not permitted to add matter by amendment which would have been obvious to the skilled person from the application.
    101. Fifth, the issue is whether subject matter relevant to the invention has been added. In case G1/93, Advanced Semiconductor Products, the Enlarged Board of Appeal of the EPO stated (at paragraph [9] of its reasons) that the idea underlying Art. 123(2) is that that an applicant should not be allowed to improve his position by adding subject matter not disclosed in the application as filed, which would give him an unwarranted advantage and could be damaging to the legal security of third parties relying on the content of the original application. At paragraph [16] it explained that whether an added feature which limits the scope of protection is contrary to Art 123(2) must be determined from all the circumstances. If it provides a technical contribution to the subject matter of the claimed invention then it would give an unwarranted advantage to the patentee. If, on the other hand, the feature merely excludes protection for part of the subject matter of the claimed invention as covered by the application as filed, the adding of such a feature cannot reasonably be considered to give any unwarranted advantage to the applicant. Nor does it adversely affect the interests of third parties.
    102. Sixth, it is important to avoid hindsight. Care must be taken to consider the disclosure of the application through the eyes of a skilled person who has not seen the amended specification and consequently does not know what he is looking for. This is particularly important where the subject matter is said to be implicitly disclosed in the original specification."
  241. A particular way in which matter can be added is known as an "intermediate generalisation". In Vector v Glatt at [9] Jacob LJ described as "uncontroversial" the description of intermediate generalisation given by Pumfrey J in Palmaz's European Patents [1999] RPC 47 at 71 as follows:
  242. "If the specification discloses distinct sub-classes of the overall inventive concept, then it should be possible to amend down to one or other of those sub-classes, whether or not they are presented as inventively distinct in the specification before amendment. The difficulty comes when it is sought to take features which are only disclosed in a particular context and which are not disclosed as having any inventive significance and introduce them into the claim deprived of that context. This is a process sometimes called 'intermediate generalisation'."
  243. The correct comparison is with the application as filed and not with the specification as granted: Triumph Actuation Systems LLC v Aeroquip-Vickers Ltd [2007] EWHC 1367 (Pat).
  244. The objection of added matter arises in this case because new claims are being added.
  245. Added matter: "control algorithm"

  246. The first objection to claim 2 is that it discloses for the first time a generic control algorithm to maintain tension in the tape. It is said that the application as filed only discloses a PID control algorithm. As elaborated in argument, Markem contended that the only disclosure was of control algorithms which would maintain the value "t" from the formula or the "difference measure" of current between predetermined limits. Accordingly there was nothing which disclosed an algorithm which maintains "tension itself" within predetermined limits as opposed to two indirect measures of tension.
  247. It is not correct to say that the disclosure in the application as filed is limited to PID algorithms in the application as filed. The PID control algorithm is stated to be an example of a control algorithm see page 289-12.
  248. It is, however, correct to say that the control algorithms disclosed in the 602 as filed are only the specific ones mentioned, namely those which keep the parameter "t" or the difference value within predetermined limits. However, the value "t" in the formula is described in some places as "tension" (see page 2724) and others as a "measure of tension" (see page 2730).
  249. The skilled person would also understand from the disclosure of the application that the object of maintaining the parameter within predetermined limits in the two cases was to maintain the "tension itself" within predetermined limits. The fact that this is so is stated expressly in relation to the specific embodiment at page 2820-21, but it did not need to say so. Accordingly, the generalised idea of a control algorithm which calculates a length of tape to maintain a parameter within predetermined limits and thereby to maintain tension is disclosed by the application as filed.
  250. Turning to the proposed amended Claim 2, this describes a control algorithm which calculates a length of tape to maintain tension. I do not think there is anything new which is taught here about the invention which was not taught by the application.
  251. Mr Arnold submitted that there was now a disclosure of something which literally calculated the length of tape to add. But, again, I do not think that there was anything new disclosed by claim 2.
  252. I reject this ground of added matter.
  253. Added matter "no monitoring of tape tension"

  254. Markem contend that claim 2 introduces for the first time the control of tape tension without any requirement to monitor tape tension. They submit that this is an intermediate generalisation. They raise the same objection to new claim 3, where the controller determines the tension, but, as I construe it, does not require monitoring.
  255. The application as filed at page 6 says the following:
  256. "Preferably the controller is arranged to control the motors to transport tape in both directions between the spools. The motors may both be stepper motors and the controller may be operative to measure tension in a tape being transported between spools mounted on the spool support and to control the motors to maintain the monitored tension between predetermined limits."
  257. This passage, and indeed the rest of the specification make it clear that control of the motors to maintain tension, the monitored tension, is achieved by monitoring something that represents tension – in particular the power supplied to the motors or the difference in currents. Plainly, the application did not restrict itself to any particular means of monitoring tension, as claim 4 in the application (now feature (e) of the amended claim 1) shows. But the overall message is that monitoring is an integral part of tension control.
  258. The passage relied on by Zipher to suggest that control of the motors to maintain tension is disclosed independently of monitoring tension is at page 6 lines 9-10 of the application:
  259. "Tension in the tape being transported is determined by control of the drive motors and therefore is not dependent upon any components which have to contact the tape between the take-up and supply spools."
  260. This passage has however to be read in context. It does not begin to suggest that monitoring of tension can be dispensed with.
  261. In my judgment both claims 2 and 3 represent impermissible intermediate generalisations. These claims are not allowable. Claim 4 does not suffer from the same defect because it requires the monitoring of tension.
  262. Added matter: control of tension

  263. Markem contend that the absence of a limitation in this claim to controlling tension between predetermined limits constitutes added matter. I can deal with this briefly in view of my earlier conclusions. Firstly, this is not really the pleaded objection. Secondly, I cannot see in the amended claim any disclosure of not controlling the tension within predetermined limits. Thirdly I think it is a permissible generalisation from what is disclosed.
  264. Amendment: Discretionary objections

    Law

  265. For many years prior to the coming into force of the Patents Act 2004, courts and tribunals in this country have exercised a very wide discretion over whether to allow a party to amend the scope of the monopoly granted by a patent following its grant. In SKF v Evans Medical [1989] FSR 561, Aldous J (as he was then) described the discretion in the following terms (at p.569):
  266. "The discretion as to whether or not to allow amendment is a wide one and the cases illustrate some principles which are applicable to the present case. First, the onus to establish that amendment should be allowed is upon the patentee and full disclosure must be made of all relevant matters. If there is a failure to disclose all the relevant matters, amendment will be refused. Secondly, amendment will be allowed provided the amendments are permitted under the Act and no circumstances arise which would lead the court to refuse the amendment. Thirdly, it is in the public interest that amendment is sought promptly. Thus, in cases where a patentee delays for an unreasonable period before seeking amendment, it will not be allowed unless the patentee shows reasonable grounds for his delay. Such includes cases where a patentee believed that amendment was not necessary and had reasonable grounds for that belief. Fourthly, a patentee who seeks to obtain an unfair advantage from a patent, which he knows or should have known should be amended, will not be allowed to amend. Such a case is where a patentee threatens an infringer with his unamended patent after he knows or should have known of the need to amend. Fifthly, the court is concerned with the conduct of the patentee and not with the merit of the invention."
  267. So the discretion travelled far and wide: it involved inquiry into the timeliness of the patentee's conduct, the patentee's state of mind about the need for amendment (involving his knowledge of the invalidating prior art and what he thought about it), the effect of the patent in its unamended state on third parties and so on. These could turn into elaborate and expensive issues to litigate. Sometimes the discretion was all that stood between the patentee and success.
  268. The discretion existed because the Patents Acts historically gave the power to allow amendment in terms classically indicative of the existence of a discretion. Those statutes left it to the courts to work out how the discretion was to be exercised.
  269. Following the United Kingdom's ratification of the European Patent Convention and the passing of the Patents Act 1977, it was doubted in a number of first instance cases whether the discretion was consistent with the Treaty and the Act, at least when there were concurrent proceedings before the court and in the EPO. The Court of Appeal, in Kimberley Clark v Procter & Gamble [2000] RPC 11 held that the Act had not introduced any change in the law.
  270. Section 75(1) of the Patents Act 1977, provided:
  271. " 75.-(1) In any proceedings before the court or the comptroller in which the validity of a patent may be put in issue the court or, as the case may be, the comptroller may, subject to section 76 below, allow the proprietor of the patent to amend the specification of the patent in such manner, and subject to such terms as to advertising the proposed amendment and as to costs, expenses or otherwise, as the court or comptroller thinks fit." (emphasis added)
  272. By section 2(5) of the Patents Act 2004, the legislature provided new guidance on how the discretion is to be exercised. This subsection provided for the insertion of a new subsection (5) into s.75 of the Patents Act 1977:
  273. "(5) In considering whether or not to allow an amendment proposed under this section, the court or the comptroller shall have regard to any relevant principles applicable under the European Patent Convention."
  274. The subsection was brought into force on 13 December 2007 by Art. 2(d) of the Patents Act 2004 (Commencement No. 4 and Transitional Provisions) Order 2007 (SI 2007 No.3396). There were no relevant transitional provisions, and so it is common ground that the new law must be applied here.
  275. A similar amendment was made to section 27 of the Act (which contains the general power to allow amendment after grant outside proceedings where validity may be put in issue) by adding a new section 27(6) in the same terms as section 75(5).
  276. Section 75, as it now stands, requires the court to "have regard to any relevant principles applicable under the European Patent Convention". Accordingly, one should turn to the Convention to see what principles are applied to considering whether or not to allow amendments.
  277. There is very little by way of express guidance in the European Patent Convention. Amendments may be made both in the course of prosecuting the application and in the course of opposition proceedings. Article 123 in its original form provided:
  278. "(1) The conditions under which a European patent application or a European patent may be amended by proceedings before the European Patent Office are laid down in the Implementing Regulations. In any case, an applicant shall be allowed at least one opportunity of amending the description, claims and drawings of his own volition."
  279. So there was one mandatory opportunity, followed by amendment under the conditions specified in the Rules. The first sentence has been amended to read:
  280. "(2) A European patent application or European patent may be amended in proceedings before the European Patent Office in accordance with the Implementing Regulations."
  281. Rules 86(2) and (3) give effect to the right to amend once in the course of prosecution as follows:
  282. "(2) After receiving the European search report and before receipt of the first communication from the Examining Division, the applicant may, of his own volition, amend the description, claims and drawings,
    (3) After receipt of the first communication from the Examining Division the applicant may, of his own volition, amend once the description, claims and drawings provided that the amendment is filed at the same time as the reply to the communication. No further amendment may be made without the consent of the Examining Division."
  283. Article 102(3) of the Convention refers in passing to "amendments made by the proprietor in the course of the opposition proceedings". The relevant rules are Rules 57 and 57A:
  284. "57(1) The Opposition Division shall communicate the opposition to the proprietor of the patent and shall invite him to file his observations and to file amendments, where appropriate, to the description, claims and drawings within a period to be fixed by the Opposition Division.
    57A Without prejudice to Rule 87, the description, claims and drawings may be amended, provided that the amendments are occasioned by grounds for opposition specified in Article 100, even if the respective ground has not been invoked by the opponent."
  285. It will be seen that Rule 57A restricts the discretion to amend to those amendments which are occasioned by grounds for opposition (including unpleaded ones). Until the introduction of that rule, the EPO only permitted amendments under Articles 102(3) and 123 which were responsive to a validity attack actually raised by an opponent.
  286. The case law of the Boards of Appeal shows that appropriateness of the amendments to the proceedings, their necessity and procedural fairness are the main, perhaps only, factors considered relevant to the discretion to allow amendment in opposition proceedings. The EPO's publication, Case Law of the Boards of Appeal states at 570:
  287. "As already mentioned, the boards of appeal have derived in particular from R. 57(1) EPC the princi