Case: Improver Corporation v Remington Consumer Products Ltd [1990] FSR 181
Outcome: cited
point of this discussion is that it may tell the Court something about construction of the claims. If the claims are confined to a single unitary reverse wound spring, might that integer be regarded as an inessential integer if there is no functional difference between a spring clutch that includes such a spring and a spring clutch that incorporates three separate springs in adjacent alignment reflecting alternate winding. Would persons with practical knowledge and experience in the subject matter addressed by the invention understand that strict compliance with a particular descriptive word or phrase appearing in a claim was intended by the patentee to be an essential requirement of the invention so that any variation would fall outside the monopoly claimed even though it could have no material affect upon the working of the invention. Lord Diplock in Catnic Components Ltd v Hill &amp; Smith Ltd (supra) noted that such a question would not arise where the variation would in fact have a material affect upon the working of the invention. The Improver or protocol questions ( Improver Corporation v Remington Consumer Products Ltd [1990] FSR 181) pose questions, the answers to which assist construction . That is to say, the questions test whether a reasonable person skilled in the art reading the language of the claims in context would think that the patentee was intending to confine the monopoly to the natural or primary meaning of the words selected or, alternatively, would such a person think that the patentee was intending to include within that meaning a variant of no material functional difference ( Root Quality Pty Ltd v Root Control Technologies Pty Ltd [2000] FCA 980 ; (2000) 177 ALR 231). Although it is true that the initial affidavit of Dr Gilmore made no reference to the points of differentiation, by reference to questions of misalignment of tabs, in the functional operation of a spring clutch incorporating three separate springs as compared with the functional operation of a spring clutch of claim 13 incorporating a single unitary reverse wound spring, the evidence of Mr Hunter and Dr Gilmore in its totality, as persons skilled in the relevant art, is such that it is simply not possible to conclude that a variation from the language of the claims of the patent in suit constituted by the use of three separate adjacent springs loaded onto shaft 1 in the manner of Exhibit 1, has no material affect upon the way the invention of claim 13 works, for the purposes of question 1 of the Improver questions. If two experts emblematic of persons skilled in the relevant art (at least for the purposes of these proceedings), cannot agree that a spring clutch incorporating three separate adjacent springs positioned on shaft 1 of a spring clutch in the manner of Exhibit 1, functions in a way which would reflect no material affect upon the evident functionality of a spring clutch incorporating a single unitary spring of reverse winding, the Court cannot be satisfied that the variation has no material affect upon functionality. The question is not to be resolved by simply accepting one person skilled in the art over another but by approaching construction taking account of the total evidence of those skilled in the art. The weight of the evidence having regard to Dr Gilmore's evidence is such that it cannot be said or found that no material affect by the use of the variant is established. That being so, Improver questions 2 and 3 do not arise. Even if I accept entirely the evidence of Mr Hunter and reject the evidence of Dr Gilmore on this aspect of the case (thus answering Improver question 1, yes) and assume or accept that the variant of adopting three adjacent separate springs of alternate winding was obvious at the date of publication of the patent in suit to a reader skilled in the relevant art (thus answering the second Improver question, yes), the answer to the third Improver question must necessarily be, no. Here, the patentee has selected language that defines a monopoly in terms of a single spring engaging a non-complex single longitudinal slot and key configuration of two shafts (coaxial with a first shaft) to achieve identified advantages of the invention. A single spring is essential to the claims. It is the integer which enables the spring clutch to discharge its clutching function. A skilled reader would understand from the language of the claims in the context of the specification that the patentee intended that strict compliance with the primary meaning of the language of the claims was an essential requirement of the invention. Moreover, Mr Hunter acknowledges that multiple springs can work in a spring clutch when they are all wound in the same direction. Having adopted the construction of the claims reflected in these reasons, that construction determines infringement. The Uniline spring clutch does not incorporate a single unitary spring of reverse winding and thus no infringement arises. The implications of claim 14