Graham Hart (1971) Pty Ltd v SW Hart & Co Pty Ltd

The plaintiff, Graham Hart (1971) Pty. Ltd., sues for infringement of its Australian letters patent no. 458,259 relating to an improved sterilizer. The defendant, S. W. Hart and Company Pty. Ltd., which admittedly had committed acts which would amount to infringement were the patent valid, counter-claims for revocation. It is with this issue of validity of the letters patent that this action has principally been concerned, although at the hearing some argument was also directed to the question of damages for infringement.

The invention the subject of the patent relates to an "improved sterilizer". Sterilizers are commonly used in hospitals, laboratories and the like where things requiring to be sterilized, such as soiled linen, are placed in a sterilizer which is then sealed and into which steam at high pressure is then admitted. The object of the invention is described in the complete specification as being "to provide an effective door seal whilst the sterilizer is in operation and in which the seal is subjected to a minimum of wear during door opening and closing operations".

At the trial the defendant's attack upon validity, extending to each of the six claims made in the complete specification, was pursued upon three distinct grounds: obviousness (Patents Act 1952, s. 100 (1) (e)), valid prior claim (s. 100 (1) (f)) and want of novelty (s. 100 (1) (g)). Other grounds pleaded were not persisted in. No point was made in the defence and counter-claim of any non-compliance with s. 40; although at times during argument some use seemed nevertheless to be being made of alleged non-compliance with the requirements of that section reliance upon it was in fact specifically disavowed.

Of the six claims in the complete specification only the first need to be set out in full: - "A sterilizer having a chamber with a loading opening fitted with a sliding door, wherein a sealing gasket is fitted into a channel or groove formed around the periphery of the door opening, such that it is closely adjacent to the inner face of the door, said channel or groove being connected to a source of high fluid pressure whereby said fluid pressure acts externally on said gasket to bring it into sealing contact with said inner face when said door is closed."

Of the remaining five claims each of the first four refers back, in turn, to the preceding claim or claims and adds a further feature; claim 2 refers to pressure in the channel around the door opening being at least equal to that in the chamber of the sterilizer; claim 3, to means to cause a partial vacuum in the channel immediately prior to the door being opened so as to bring the gasket from sealing contact with the door; claim 4, to a gasket in the form of a sealing ring; claim 5, to a counting of the sliding door such as will prevent its outward movement. The last claim, claim 6, refers to a sterilizer substantially as thereinbefore described with reference to the drawings accompanying the specification.

Because of the particular character of the defendant's attack upon the validity of these claims I can deal with certain aspects of it quite broadly. This arises from the fact that evidence both of want of novelty and of obviousness was confined to the tendering of a number of prior United States and United Kingdom letters patent and of one prior Australian letters patent, the latter also providing the only evidence in support of the allegation of valid prior claim; no prior use in Australia, as distinct from prior publication, was alleged and the only evidence of prior publication consisted of these prior letters patent.

Accordingly, the attack upon validity proceeded upon a narrow front, based as it was upon the material contained in these prior patent specifications. It was characterized by an initial and sustained criticism of the form of the claims, in particular of claim 1 which was said to be of excessive width and to claim as the area of monopoly all sterilizers fitted with sliding, as distinct from swinging, doors and which employed a pressure operated gasket as sealing device. Were the claims, upon their proper construction, to be so construed as claiming monopoly in respect of gasket-equipped, pressure-sealed, sliding door sterilizers, they could no doubt readily enough be shown to be unsustainable; a 1968 United States patent, the Nugent patent, would have anticipated them by some years.

However I do not regard claim 1, or, for that matter, any of the other claims, as making any claim to a monopoly of the width suggested by the defendant. It is true that if attention be confined to the body of the specification, rather than to the claims, what there appears might possibly be open to this interpretation. A considerable amount of attention is given in the body of the specification to the use of a sliding door and to its various advantages, which include relative ease of operation, efficient use of available space and, perhaps most important, safety. This could perhaps mislead one into reading the claims in the way in which the defendant contends that they should be read. But to concentrate upon the body of a specification, including the consistory clause, and to disregard the words of the claims is the precise converse of established canons of interpretation of patent specifications. The proper course is to regard the claims as the primary text, recourse being had to the body of the specification only as a context available for reference in the event of ambiguity. Once this course is adopted this particular criticism, of excessive width of claim, is revealed as unfounded.

The words of claim 1 do not, of themselves, give rise to any ambiguity and a reading of them describes a claim quite narrow in the extent of the monopoly which is sought. The claim begins by describing a sterilizer having its loading opening fitted with a sliding door; it goes on to describe the sealing gasket, so fitted into a recess around the door opening as to be close to the inner face of the door; that recess is then described as so connected to a source of high fluid pressure as to allow that pressure to act externally upon the gasket to bring it into sealing contact with the door when closed. In the particular embodiment described in the body of the specification, steam is used to exert this pressure so that when the door is closed and steam under pressure is admitted to the recess it presses the gasket forward against the inside of the door, sealing it.

It is not contended by the plaintiff that any one feature described in claim 1 is itself novel. Rather it is this particular combination of known integers which is said to be both novel and inventive, the combination of a sterilizer, a sliding door, a sealing gasket situated in a recess and the use of external pressure upon the sealing gasket, causing it to protrude from the recess so as to make a seal against the inside of the closed door. Heretofore pressure-operated sealing gaskets for sliding door sterilizers have been conceived of but these have relied upon pressure applied internally to a hollow gasket rather than externally, as proposed in the patent in suit.

So construed there arises no question of the existence of any valid prior claim (s. 100 (1) (f)). There is no evidence before me of any other letters patent in any way covering this particular combination of integers. The plaintiff has, because of the quite narrow scope of the claim resulting from the combining together of a number of integers, succeeded in claiming an area of monopoly very narrow in scope but which has not been shown to have been the subject of any prior claim. It is nothing to the point that each of the integers which the claims combine together may have been the subject of prior claims; it is only for a particular combination of them and not for each of them severally that monopoly is claimed. I would add, moreover, that the only prior claim particularized in the defendant's pleadings is an Australian letters patent which deals exclusively with a sealing device and has no relevance to the combination claimed in the patent in suit.

In any event, although pleaded as a distinct ground of objection, the objection under s. 100 (1) (f) is on the facts of the present case, wholly covered by the scope of the objection under s. 100 (1) (g), want of novelty. This is because the only conceivably relevant prior claims had already been published in Australia well before the priority date of the patent in suit and would thus provide material suitable for consideration under the head of want of novelty without recourse to the more limited objection of valid prior claim.

I turn, then, to the objection under s. 100 (1) (g), that claim 1 lacks novelty. It fares no better than does the objection founded on valid prior claim. Once the patent in suit be understood as a claim to a combination, that particular combination may, on the evidence before me, be seen to be undoubtedly novel although no single one of its integers can be regarded as such. As I have said, its novelty lies in the inclusion of the integer involving the use of external pressure to activate the sealing gasket. The only prior letters patent calling for any real consideration as a possible anticipation is the Nugent patent, which I will later have to describe in some detail when dealing with obviousness. For present purposes it is enough to say of the Nugent patent that, although what it deals with is in many respects very similar to the patent in suit, the method of sealing which it envisages is quite distinct, relying as it does upon the inflation of a hollow seal for its sealing effect rather than upon fluid pressure acting externally upon a sealing gasket. This difference is in my view ample to ensure that the Nugent patent does not anticipate the patent in suit.

If claim 1 be immune from attack upon the grounds of valid prior claim and of want of novelty the immunity of the remaining claims is a fortiori; claims 2 to 5, by introducing additional features or a more precise description of an existing feature, lay claim to still narrower areas of monopoly than does claim 1 and are likewise not susceptible to attack upon either of these grounds. Claim 6 is merely an embodiment of claim 1 incorporating a number of these additional features.

The third objection to validity, that concerned with obviousness (s. 100 (1) (e)), cannot be disposed of so readily. It is said on behalf of the defendant that no inventive step is involved in combining together, as does claim 1, the several known integers with which it is concerned, that the particular combination was an obvious one and cannot for that reason give rise to any valid claim to monopoly. This submission calls for some consideration of the terms of s. 100 (1) (e), viewed in the light of the particular evidence before me going to the issue of obviousness.

That evidence consists, as I have already said, of prior letters patent, there being little, if any, oral evidence and no other written material concerning the state of relevant common knowledge in the art at the priority date of the patent in suit. The only witness who gave evidence directed very little of his testimony to this question of the state of the prior art. My conclusion on the issue of obviousness must therefore be based upon whatever may legitimately be derived from the prior patent specifications which are in evidence, tendered by the defendant.

Before the passing of the Patents Act 1952 the absence of testimony concerning the extent of common knowledge might, I think, have been fatal to the defendant's objection based upon obviousness. The question is whether, and to what extent, the tendered specifications may, in the light of s. 100 (1) (e), constitute evidence of obviousness and lack of an inventive step despite the absence of oral evidence of the scope of common knowledge in the art. Paragraph (e) reads as follows:

that the invention, so far as claimed in any claim, was obvious and did not involve an inventive step, having regard to what was known or used in Australia on or before the priority date of that claim. It is, in particular, with the words "having regard to what was known or used in Australia" that I am concerned. Do these words require obviousness to be judged having regard to all paper anticipations actually available in Australia at the priority date, whether or not they formed any part of the common knowledge of those skilled in the art, thereby substituting for the customary criterion of obviousness, common knowledge in the art, the wider one of public knowledge? Or have these words some less radical effect and, if so, what new criterion do they prescribe?

The meaning and effect of the words "known or used in Australia" has been referred to in this Court on a number of occasions. Perhaps the most exhaustive discussion of the matter is to be found in the judgment of Windeyer J. in Sunbeam Corporation v. Morphy-Richards (Aust.) Pty. Ltd. [1] . There his Honour concluded that he should assume, in considering the issue under par. (e), that the hypothetical person skilled in the art, by reference to whom inventiveness was to be judged, was not only possessed of the stock of common knowledge in the art but was also acquainted with the particular prior specifications which were in evidence. However his Honour nevertheless found some difficulty in the proposition that, in judging of the obviousness of an alleged invention, par. (e) had made all published information which was available in Australia, however recondite and esoteric, of the same importance as matters of true common general knowledge. His Honour, partly, perhaps, as a result of this difficulty which he felt, added three riders to his general conclusion, of which two are presently relevant: (1) a mere paper anticipation, although to be treated as "known in Australia", does not have "quite the same effect in determining obviousness as does something that was in truth a matter of common knowledge"; (2) assuming that par. (e) has the effect stated above, "the best approach to this question is still that indicated by Dixon J. in Acme Bedstead Co. Ltd. v. Newlands Bros. Ltd [2] , that is to say before coming to particular documents or things put forward as anticipations, the state of the general knowledge at the relevant date should be considered" [3] .

1. (1961) 35 A.L.J.R. 212. 2. (1937) 58 C.L.R. 689, at pp. 707-708. 3. (1961) 35 A.L.J.R., at p. 219.

It would seem therefore that his Honour was clearly of the opinion that the long established distinction between common knowledge, the correlative of inventiveness or subject matter, and public, or available, knowledge, the correlative of novelty, had not been wholly obliterated by the wording of par. (e), appearing in the Act of 1952, and that where the objection to validity is founded upon s. 100 (1) (e) it is primarily to be established by reference to what was truly common knowledge at the relevant date. His Honour discusses in his judgment the two earlier decisions of this Court which advert to this question (H.P.M. Industries Pty. Ltd. v. Gerard Industries Ltd [4] , per Williams J., and John McIlwraith Industries Ltd. v. Phillips [5] , per Dixon C.J. (with whom Fullagar J. agreed)). The matter has also been touched upon more recently in Welch Perrin & Co. Pty. Ltd. v. Worrell [6] , per Dixon C.J., Kitto and Windeyer JJ. and in Universal Oil Products Co. v. Monsanto Co. [7] , per Gibbs J. There Gibbs J., in the course of an examination of the then state of the authorities, described the meaning of known in par. (e) as an "open question" which it was unnecessary for him to decide in the circumstances of that case. In AMP Incorporated v. Utilux Pty. Ltd. [8] , McTiernan J. said this of the effect of par. (e):

I would, however, say that I am not convinced that the common general knowledge in the present case must be taken as having been, without any limitation, augmented by all the minute detail of twenty two specifications ranging over a period of thirty-seven years, and claiming inventions as various as a "method of fabricating a generally cylindrical magnetic structure" and a "method of producing slide fasteners". 1. (1957) 98 C.L.R. 424, at pp. 437-438. 2. (1958) 98 C.L.R. 529, at p. 530. 3. (1961) 106 C.L.R. 588, at p. 622. 4. (1972) 46 A.L.J.R. 658, at pp. 659-660. 5. (1971) 45 A.L.J.R. 123, at p. 134.

All of these decisions accept that the scope of the objection based on obviousness has been enlarged by the Act of 1952 but, with the exception of Sunbeam Corporation [9] and AMP Incorporated [10] , no indication has been given of the precise limits of the enlargement.

1. (1961) 35 A.L.J.R. 212. 2. (1971) 45 A.L.J.R. 123.

The question of the meaning of "known or used" has also arisen in the courts in England. There the difficulty is perhaps more pronounced, for the English equivalent of the objection as to want of novelty in s. 100 (1) (g) - s. 32 (1) (e) of the Patents Act, 1949 U.K. - itself includes the words "having regard to what was known or used". Some difficulty has accordingly been felt in giving other than an identical effect to these words where they occur in each of pars. (e) and (f) of s. 32 (1) (the latter being the equivalent to our s. 100 (1) (e)). Nonetheless, it seems that the tendency is to do just this. In Technograph Printed Circuits Ltd. v. Mills & Rockley (Electronics) Ltd. [11] , Lord Reid (with whom Lord Morris of Borth-y-Gest agreed) said:

"I desire to say that I am very far from being convinced that he" [the skilled technician who is well acquainted with workshop technique and who has carefully read the relevant literature] "must be supposed to have studied every specification or other document which would be relevant on an issue of novelty. I understand that it is now quite common for those seeking guidance to make extensive searches of British and foreign specifications and our hypothetical addressee must be supposed to have done as much research as such persons in fact do. But there may be documents which, although available, would never be looked at by anyone making such a search as our hypothetical addressee is supposed to have made. Attention was drawn to the fact that both heads (e) and (f) in s. 32 contain words "having regard to what was known or used in the United Kingdom". I doubt whether they were intended to mean the same in each case. If they were there would now be little, if any difference between novelty and obviousness." In saying this his Lordship identifies the very problem which arises in the interpretation of s. 100 (1) (e) of the Australian Act, that with which Windeyer J. wrestled in the Sunbeam Corporation Case [12] . His Lordship went on to say [13] : "I think that in head (f) the words should have the more natural meaning of what was or ought to have been known to a diligent searcher." 1. [1972] R.P.C. 346, at p. 355. 2. (1961) 33 A.L.J.R. 212. 3. [1972] R.P.C., at p. 355.

Lord Diplock was of a different opinion, and said [14] : "I do not, as at present advised, think that the meaning of those words is any different in par. (e)". Lord Reid's view, although expressed obiter, gained some support from the Court of Appeal (Sachs, Buckley and Orr L.JJ.) in General Tire & Rubber Co. v. Firestone Tyre and Rubber Co. Ltd. [15] . "Known", their Lordships said, would include "what a competent addressee ought to know" but should not be unreasonably extended; Lord Reid's concept of the diligent searcher was that adopted and enlarged upon by the Court (see also Letraset International Ltd. v. Dymo Ltd. [16] , per Graham J.).

1. [1972] R.P.C., at p. 361. 2. [1972] R.P.C. 457, at pp. 499-500. 3. [1976] R.P.C. 65, at p. 77.

The fact that s. 100 (1) (g) of the Patents Act 1952 does not include the words "known or used in Australia" makes it the easier to apply to those words, where they occur in s. 100 (1) (e), the reasoning of Lord Reid in the Technograph Case [17] . We are, in Australia, not confronted with difficulties of interpretation related to the giving of a different meaning to the same words in the same Act.

I have concluded that I should regard the words "having regard to what was known or used in Australia" in par. (e) as enabling mere paper anticipations to be probative of obviousness but only if they would have been known to a diligent searcher skilled in the particular art. What has been said in the English decisions provides support for this view, which is also consistent with statements in the past judgments of this Court to the effect that par. (e) has enlarged the scope of the objection based upon obviousness. This view also preserves a distinction between obviousness and want of novelty so far as the proof of each is concerned and reflects the concern of Windeyer J. and of McTiernan J. lest quite obscure prior specifications should improperly be admitted to the ranks of true common knowledge. I do not know whether I have fully appreciated the precise effect of Windeyer J.'s first rider, as I have called it, as he articulated it in the Sunbeam Corporation Case [18] . However the facts of the present case, where the only evidence bearing on the issue of obviousness consists of prior specifications, would, in any event, afford little room for the application of either of his Honour's two riders.

In any consideration of par. (e) it is important to bear in mind that obviousness is, after all, a question of fact. Items of evidence adduced in support of such an objection may range from the highly probative, of compelling weight, to evidence which is of no probative value on the issue of obviousness because it lacks the quality of being such as would have been known to a diligent searcher. Lacking that quality, it cannot go to the issue of obviousness. Again the effect of any item of evidence will much depend upon the totality of testimony, so that if acceptable oral evidence of common general knowledge has been given which so defines that area as not to include the material contained in such a paper anticipation it will be the easier to reject the latter as evidence of obviousness.

The present case is a quite special one because there was in substance no oral evidence of the extent of common general knowledge. Instead there were in evidence patent specifications particularized in the pleadings as relied upon as going to obviousness. Two of these were by no means recondite or esoteric; I refer to the two United States patents, no. 3,266,657, the Stachiw patent, and no. 3,339,785, the Nugent patent. Both are recent United States letters patent which on their face may be seen to bear directly upon the problem said to be solved by the plaintiff's invention. The Stachiw patent, published in Australia in April 1967, is entitled "Sealing of internal high pressure vessels" and the opening words of the body of the specification described the invention as relating to "sealing of covers for tanks containing gas or fluid under high pressure", particularly under circumstances where there is considerable clearance between cover and tank body. It goes on to describe the prior art and the use of seals relying upon compression for their sealing effect. The claims include as features the use of a flexible circular sealing ring which, together with its metal retaining ring assembly, rises from a recess around the tank opening when fluid or gas is injected under pressure into the recess, thereby causing the sealing ring to make sealing contact with the cover.

The second letters patent, the Nugent patent, published in Australia in February 1968, is entitled "Closure apparatus for pressure chamber" and the invention is described as relating to "apparatus for closure and sealing of pressure chambers and more specifically to apparatus for closure and sealing of pressurizable sterilizing chambers". Three of the recited objects of the invention are particularly significant. One is said to be "to provide improved apparatus for closing and sealing a pressure chamber", another "to provide an improved door or closure construction for a pressure chamber eliminating the need for conventional locking means for securing the door in closed and sealed relationship with the opening of the pressure vessel", a further "to provide a slidable door with means for limiting the outward movement of the door away from the pressure vessel opening when at least in the closed position with the opening". The invention includes as features a sliding door sealed by means of a circular seal which is inflated internally under pressure so as to provide a seal between door and pressure vessel when the sliding door is closed.

These two specifications, each in the English language, of recent date and concerned with appliances and with functions of those appliances cognate with those with which the patent in suit deals, may, in my view, be seen upon their face to form a part of the relevant prior art for present purposes. They would, I think, have been so identified by a skilled and diligent searcher making his inquiries in Australia at the priority date of the patent in suit, in September 1972, and who was concerned with the problem of the effective sealing of the sliding door of a sterilizer in which steam at high pressure might be used for the sterilizing processes.

It follows that, despite the absence of oral testimony as to common knowledge, I should pay regard to these two specifications in judging of the objection of obviousness. The crucial question is thus reached: would such an improvement as is claimed in the patent in suit be obvious, at the priority date, to a person skilled in the art who was intent upon discovering a suitable improvement but who lacked all inventive powers? I am compelled to answer "Yes". We are here concerned with a number of integers or features each of which is in itself already well known; what the invention does is associate them together in a particular way. The Nugent patent would itself inform one, if it were not already well known, that a sterilizer may have a sliding door and may be fitted with a sealing gasket positioned so as to be "intermediate the door and the pressure vessel around the opening thereof". It would also teach that that sealing gasket may be pressure inflated so that upon inflation, but only then, its exterior surface makes contact with the sliding door and seals it. The Stachiw patent would cover much the same field in the case of a non-sliding door but would inform one, were it not already obvious, that to ensure that the exterior surface of the sealing gasket was well clear of the sliding door when the latter was in motion the gasket might be housed in a recess around the opening of the sterilizer, being brought into contact with the door, when shut, not by inflation, as in the Nugent patent, but by pressure from behind forcing it partially to emerge from its recess and seal against the door.

It is then informative to compare all this with the consistory clause of the patent in suit, which reads:

Accordingly the invention resides in a sterilizer having a chamber with a loading opening fitted with a sliding door wherein a sealing gasket is fitted into a channel or groove formed around the periphery of the door opening, such that it is closely adjacent to the inner face of the door, said channel or groove being connected to a source of high fluid pressure whereby said fluid pressure acts externally on said gasket to bring it into sealing contact with said inner face when the door is closed. That being the inventor's own description of what he has invented I am unable to regard it as involving any inventive step having regard to the prior art. It appears to me to be wholly obvious. In saying this I have not, I think, overlooked the natural tendency unduly to discount the inventive character of an invention once it has been explained, particularly in the case of an invention consisting of the combining together of known integers.

What I have said deals specifically with claim 1 of the patent in suit and applies equally to claims 2, 4, and 6. Claims 3 and 5 call for brief individual mention. Claim 3 adds the integer of a means to cause a partial vacuum in the channel behind the gasket, immediately before the door is opened, so as to break the seal by causing the gasket to retract into the channel. I cannot regard this, in itself, as an inventive step. It is little more than the reverse cycle of the step involved in making the seal; the pressure behind the seal which was applied so as to make the seal is to be withdrawn and the process is then taken but a little further by the positive creation of a partial vacuum in its place. So far as concerns claim 5, which claims a front panel mounting for the sliding door, preventing outward movement of the door, this is precisely covered by details of the Nugent patent.

This is, then, a case, to use the language of Maugham J. in Adelmann and Ham Boiler Corporation v. Llanrwst Foundry Co. [19] , where "the alleged invention, though possessing the advantages of being an excellent design, is simply the application of a well known and well understood piece of mechanism to achieve an obvious advantage, and is not the proper subject of letters patent". The plaintiff's combination is undoubtedly an excellent design incorporating advantages not possessed by the Nugent apparatus but does not in my view possess the requisite quality of any inventive step. In reaching this conclusion I have gained considerable assistance from the decision of this Court in Acme Bedstead Co. Ltd. v. Newlands Bros. Ltd. [20] , and from the principles there laid down.

1. (1928) 45 R.P.C. 413, at p. 420. 2. (1937) 58 C.L.R. 689.

Having decided that the plaintiff's patent ought to be revoked, no question now arises of the measure of damages, the remaining matter which was the subject both of argument and of evidence at the trial of this suit.

Accordingly, I would dismiss the plaintiff's action. The counterclaim succeeds and the plaintiff's letters patent must be revoked. The plaintiff must pay the costs of the action.

I have had the advantage in this appeal of reading the reasons for judgment prepared by my brother Aickin. I am in entire agreement with his conclusion and with his reasons supporting it.

In my opinion, the appeal should be allowed and the matter remitted to my brother Stephen to consider the making of the injunction and an order for damages for infringement.

The facts are set out in the reasons for judgment of Aickin J. which I have had the advantage of reading. The question of obviousness was the only question argued on this appeal. No challenge was made to the conclusion of Stephen J. that the claim to revocation based on lack of novelty failed. In particular I would note that it has not been submitted that the receipt in 1970 by the respondent in Australia (from the Sybron Corporation under a licence agreement of which few details appear in the evidence) of microfilms agreed at the hearing to contain the information included in the United States Macdonald patent was a prior publication in Australia which could show lack of novelty.

The appellant is the patentee of a patent of which the first three claims are as follows:

1. A sterilizer having a chamber with a loading opening fitted with a sliding door, wherein a sealing gasket is fitted into a channel or groove formed around the periphery of the door opening, such that it is closely adjacent to the inner face of the door, said channel or groove being connected to a source of high fluid pressure to bring said gasket into sealing contact with said inner face when said door is closed.

2. A sterilizer as claimed in claim 1 which is pressurised wherein the pressure in said channel is at least equal to that in the chamber.

3. A sterilizer as claimed in claim 1 or 2 comprising means to cause a partial vacuum to be created in said channel, immediately prior to the door being opened, to bring said gasket from sealing contact with said door.

There was no patentable invention in designing a sterilizer having a sliding door and a groove around the door opening in which there was a seal or gasket. Further there was no patentable invention in using a seal or gasket one of the surfaces of which could by high fluid pressure be brought into sealing contact with the inner face of the door. This was the subject of the 1968 Nugent patent which in particular specified an inflatable gasket. There was no patentable invention in a seal or gasket for a pressurised container which was not inflatable but which attained its sealing effect by high fluid pressure applied externally to the seal. This was described in the Stachiw patent, published in Australia in April 1967.

What was claimed in the instant patent was a particular combination of integers. Stephen J. accepted the submission that the claim should be so regarded and held that, when it was so regarded, there was no prior claim which covered the particular combination of integers and that the particular combination was novel even though no single one of its integers could be regarded as such. The novelty in relation to a pressurised sterilizer with a sliding door lay, he held, "in the inclusion of the integer involving the use of external pressure to activate the sealing gasket".

Stephen J. then proceeded to consider whether the inclusion of this additional integer in the combination was an obvious step and he held that it was. He relied particularly upon the fact that details of the Stachiw patent had been published in Australia in April 1967 and details of the Nugent patent in 1968.

Whether the incorporation of the integer involving the use of external pressure to activate the sealing gasket in a combination with a pressurised sterilizer having a sliding door was an obvious step depends initially upon whether the idea of an externally pressured seal was, in a relevant sense, "known" in Australia at the priority date of the appellant's patent. However, it does not follow, even if the idea of such a seal was known, that its application to a pressurised sterilizer with a sliding door was obvious. But first what is meant by "known"? If it means "known to any member of the public in Australia" then clearly there was no such knowledge. If it means that the use of high fluid pressure externally applied to a seal or gasket was part of the everyday knowledge of a person skilled in the art of sealing pressurised containers, there is no evidence of this at all. But if it means that the knowledge was available and more likely than not would be sought out and found in the place where it was available by a person skilled in the art who was seeking an improved way of sealing pressurised containers, then the question becomes one of the degree of availability. Where was the knowledge available? Would a person skilled in the art more probably than not go to that place in search of the knowledge? In that place was it readily available or was it hidden away in the corner of a publication where no one ordinarily would be likely to look for or find it?

Stephen J. having discussed the previous cases - and I shall adopt but not repeat that discussion - in effect adopted the meaning and application of the word "known" in s. 100 (1) (e) of the Patents Act 1952 Cth which I have lastly described. He said:

I have concluded that I should regard the words "having regard to what was known or used in Australia" in par. (e) as enabling mere paper anticipations to be probative of obviousness but only if they would have been known to a diligent searcher skilled in the particular art. And later: In any consideration of par. (e) it is important to bear in mind that obviousness is, after all, a question of fact; items of evidence adduced in support of such an objection may range from the highly probative, of compelling weight, to evidence which is of no probative value on the issue of obviousness because it lacks the quality of being such as would have been known to a diligent searcher. Lacking that quality, it cannot go to the issue of obviousness. Again the effect of any item of evidence will much depend upon the totality of testimony, so that if acceptable oral evidence of common general knowledge has been given which so defines that area as not to include the material contained in such a paper anticipation it will be the easier to reject the latter as evidence of common general knowledge. Stephen J. went on to say: The present case is a quite special one because there was in substance no oral evidence of the extent of common general knowledge; instead there were in evidence patent specifications particularized in the pleadings as relied upon as going to obviousness. Two of these were by no means recondite or esoteric; I refer to the two U.S. patents, No. 3,266,657, the Stachiw patent, and No. 3,339,785, the Nugent patent. Both are recent United States letters patent which on their face may be seen to bear directly upon the problem said to be solved by the plaintiff's invention. Stephen J. examined the two patents and continued: These two specifications, each in the English language, of recent date and concerned with appliances and with functions of those appliances cognate with those with which the patent in suit deals, may, in my view, be seen upon their face to form a part of the relevant prior art for present purposes. They would, I think, have been so identified by a skilled and diligent searcher making his enquiries in Australia at the priority date of the patent in suit, in September 1972, and who was concerned with the problem of the effective sealing of the sliding door of a sterilizer in which steam at high pressure might be used for the sterilizing processes.

It follows that, despite the absence of oral testimony as to common knowledge, I should pay regard to these two specifications in judging of the objection of obviousness. The crucial question is thus reached: would such an improvement as is claimed in the patent in suit be obvious, at the priority date, to a person skilled in the art who was intent upon discovering a suitable improvement but who lacked all inventive powers? I am compelled to answer "Yes". We are here concerned with a number of integers or features each of which is in itself already well known; what the invention does is associate them together in a particular way. The Nugent patent would itself inform one, if it were not already well known, that a sterilizer may have a sliding door and may be fitted with a sealing gasket positioned so as to be "intermediate the door and the pressure vessel around the opening thereof". It would also teach that the sealing gasket may be pressure inflated so that upon inflation, but only then, its exterior surface makes contact with the sliding door and seals it. The Stachiw patent would cover much the same field in the case of a non-sliding door but would inform one, were it not already obvious, that to ensure that the exterior surface of the sealing gasket was well clear of the sliding door when the latter was in motion the gasket might be housed in a recess around the opening of the sterilizer, being brought into contact with the door, when shut, not by inflation, as in the Nugent patent, but by pressure from behind forcing it partially to emerge from its recess and seal against the door.

Of claim 3 he said: Claim 3 adds the integer of a means to cause a partial vacuum in the channel behind the gasket, immediately before the door is opened, so as to break the seal by causing the gasket to retract into the channel. I cannot regard this, in itself, as an inventive step. It is little more than the reverse cycle of the step involved in making the seal; the pressure behind the seal which was applied so as to make the seal is to be withdrawn and the process is then taken but a little further by the positive creation of a partial vacuum in its place.

Not without considerable hesitation I have come to a different conclusion and that conclusion follows from a somewhat different approach to the question which must be decided. The integer which gave novelty was the seal activated by high fluid pressure externally applied. No seal for a pressurised container such as a sterilizer either inflatable as in the Nugent patent or externally pressured as in the Stachiw patent had previously been used in Australia. The particular problems which might arise in such use were not known in the art.

Stephen J. posed the critical question as whether the improvement claimed in the patent was obvious, at the priority date, to a person skilled in the art who was intent upon discovering a suitable improvement but who lacked all inventive powers. I would respectfully agree that if the problem of other kinds of pressure seal, in particular the inflatable seal, were known, then any person skilled in the art would most likely examine recent patented inventions in order to see what other kinds of pressured seal there were and he would probably come upon the Stachiw seal. But there are two other elements which need to be taken into account. First, it would need to be obvious that the principle of the Stachiw seal was able to be used on a sliding door sterilizer as well as on a pressurised container with a bolted cover, as described by Stachiw. I am prepared to assume that this was obvious and proceed to the second element, namely, that it would need to be obvious to a person designing a pressurised sterilizer with a sliding door and seeking to solve the problem of sealing the door that the externally pressured seal had some advantage over the inflatable seal which made its adoption desirable. In my opinion the respondent failed to produce any evidence to support a conclusion that this was obvious.

The difficulty which is faced when reliance is placed solely on a collection of prior specifications particularly in the case of a combination patent is that there may be no obvious way of recognizing the problem which one particular combination will cause and which requires solution, the advantage which the selection of a different integer has over the one in another combination.

The Nugent patent proposed a pressurised sterilizer with a sliding door sealed by a pressured seal. No one in Australia knew at the priority date whether such a sliding door with such a seal would work satisfactorily in practice. There is nothing to support a conclusion that it was obvious that it would have the particular defect which in fact it had - non-retraction of the seal and consequent damage thereto when the door was slid open and shut. It therefore does not assist the respondent that it might have been obvious that a seal activated by external pressure which would withdraw on release of pressure would in whole or part overcome a problem, when the problem itself was not obvious.

So far I have dealt with the subject on the basis of claim 1. The retraction of the seal under that claim would depend on the withdrawal of the external pressure. Under claim 3 the retraction would be by a positive means of creating a partial vacuum behind the seal. Since I am of the opinion that the use of the externally pressured seal in the combination as described in claim 1 was not obvious it follows a fortiori that the addition of a positive means of withdrawing the seal was not obvious. I agree that the appeal should be allowed and I concur in the order proposed by Aickin J.

Stephen J., from whose judgment this appeal is brought, dismissed an action for infringement and, on the counterclaim, revoked the patent. He found that the claimed invention was "wholly obvious" within s. 100 (1) (e) of the Patents Act 1952 Cth. As his reasons show, he was well aware of the dangers of hindsight.

A technological improvement does not necessarily involve an inventive step, but there is a growing tendency to claim and obtain a patent for each one as if it did. In Savage & Co. Ltd. v. Harris (D.B.) & Sons [28] Lopes L.J. said:

The material question to be considered in a case like this is, whether the alleged discovery lies so much out of the track of what was known before as not naturally to suggest itself to a person thinking on the subject; it must not be the obvious or natural suggestion of what was previously known. It was pointed out in Terrell on the Law of Patents, 12th ed. (1971), at p. 126 that "in that test the "person thinking on the subject" must be the notional skilled person in the particular field". On this question of fact, I agree with Stephen J. The claimed invention was obvious. 1. (1896) 13 R.P.C. 364, at p. 370.

This is an appeal from an order made by Stephen J. in a patent suit by which he dismissed an action for infringement and allowed a counterclaim for revocation in respect of Letters Patent No. 458,259 for an improved sterilizer. That patent was granted as of 29th August 1973, having a priority date of 21st September 1972. The date of publication of the application does not appear but must have been during 1973.

At the hearing there was no issue as to infringement, it being admitted by the defendant that if the patent was valid it had been infringed. The admission was in general terms and did not distinguish between individual claims. However its validity was challenged on a number of grounds of which only two were pressed. They were obviousness and want of novelty. As to the first the particulars of objection stated that:

(C) The invention was obvious and did not involve an inventive step having regard to what was known or used in Australia on or before the priority date of the claims. There followed under the heading "Particulars of Previous Publication" (as amended) a list of some twenty-two letters patent, some from the United States of America, some from the United Kingdom and one from Australia, as well as documents no longer material. In fact thirteen letters patent were put in evidence. The paragraph then stated: "The invention claimed in the 6 claims is a combination of common general knowledge and/or the subject matter of the specifications to the Australian and American Patents referred to above" and a further eight listed United States patents.

Paragraph (E) of the particulars of objection was as follows: "The invention claimed in paragraphs 1 to 6 of the claims (or in one or more of those claims) was not novel in Australia on the priority date." Particulars were stated to be the particulars of previous publication set out above.

The specification states that the object of the invention is to provide an effective door seal whilst the sterilizer is in operation and in which the seal is subjected to a minimum of wear during door opening and closing operations. It refers to previous sterilizers using swing doors and their disadvantages. There is no single consistory clause in the specification, but the nature of the invention is described in the following two passages:

Accordingly the invention resides in a sterilizer having a chamber with a loading opening fitted with a sliding door wherein a sealing gasket is fitted into a channel or groove formed around the periphery of the door opening, such that it is closely adjacent to the inner face of the door, said channel or groove being connected to a source of high fluid pressure whereby said fluid pressure acts externally on such gasket to bring [it] into sealing contact with said inner face when the door is closed. It is preferable that when the invention is applied to pressurised sterilizers the pressure of the fluid in the channel is greater than that inside the chamber.

When the door is in the closed position there is a small amount of clearance between the front edges of chamber (6) and the inner face of the door (8) such as to allow for free vertical movement of the door. The front edges of the chamber have a channel or groove (30) around the periphery of the door opening with a sealing ring (32) of rubber or similar suitable material slidably mounted therein. The channel or groove can be connected to a source of high fluid pressure which is in this example steam pressure. On the closing of the door and prior to the sterilizing operation steam under pressure is admitted to the channel (30) so forcing the sealing ring (32) into a sealing engagement with the door (8) (Fig. 3B). Prior to the opening of the chamber the steam pressure is removed from, and a partial vacuum created in channel [30] to cause sealing ring (32) to retract back into the channel and away from the door (Fig. 3A).

A sterilizer having a chamber with a loading opening fitted with a sliding door, wherein a sealing gasket is fitted into a channel or groove formed around the periphery of the door opening, such that it is closely adjacent to the inner face of the door, said channel or groove being connected to a source of high fluid pressure to bring said gasket into sealing contact with said inner face when said door is closed.

A sterilizer as claimed in claim 1 which is pressurised wherein the pressure in said channel is at least equal to that in the chamber.

A sterilizer as claimed in claim 1 or 2 comprising means to cause a partial vacuum to be created in said channel, immediately prior to the door being opened, to bring said gasket from sealing contact with said door.

A sterilizer as claimed in any one of the preceding claims wherein said gasket is a sealing ring.

A sterilizer as claimed in any one of the preceding claims wherein said door is slidably mounted between a front panel of the sterilizer and the periphery of said chamber, such that said front panel prevents outward movement of said door.

A sterilizer substantially as hereinbefore described with reference to the accompanying drawings.

It will be observed that it is only claim 3 and the succeeding claims which embody the whole of the invention referred to in the above passages from the body of the specification. It is thus not sufficient to look only at claim 1. Claim 6 is a "Raleigh Cycle" kind of claim and adds nothing for present purposes.

Stephen J. found that the invention as claimed was not bad for want of novelty and that ground of objection was not advanced in argument on the appeal. Stephen J. found however that the invention as claimed was obvious.

The case is an unusual one in that no oral evidence was given of the common general knowledge of the hypothetical skilled addressee familiar with the relevant art, nor of the state of the relevant art in Australia at the priority date. Reliance was placed exclusively on prior publications without any oral evidence as to what a man skilled in the art would have got from them at the relevant date. Of the thirteen patents relied on, Stephen J. referred to only two, namely United States Patent No. 3,266,657 (Stachiw's patent) relating to "sealing of internal high pressure vessels" published in Australia by becoming available for inspection in the Patent Office Library on 14th April 1967 and United States Patent No. 3,339,785 (Nugent's patent) relating to "closure apparatus for pressure chamber" which became available for inspection in Australia on 29th February 1968. In argument on appeal reference was made only to Nugent's patent to which I refer below.

Stachiw's patent relates to the sealing of covers for tanks containing gas or fluid under high pressure, in particular to the sealing of such covers under circumstances where there is considerable clearance between the cover and the tank body. It relates to tanks which have a removable lid secured by substantial bolts fitting into threaded holes in the walls of the tank. The invention there claimed, so far as material, relates to a resilient annular gasket placed in a groove which is concentric with the body of the tank and which also contains a metal ring which rises in the groove by the application of fluid pressure to the bottom of the metal ring. That causes the sealing ring to rise and come into sealing contact with the top cover after the bolts have been screwed into place. The effect of the pressure against the sealing ring is to deform it so that it is pressed down wholly into the groove or channel, the sealing being attained in that way.

Nugent's patent is described as one for the closure and sealing of "pressurizable sterilizing chambers". The greater part of the specification is concerned with the sliding door and the means for retaining the sliding door in place by flanges suitably arranged. The other aspect is described as follows: "It is another important object of this invention to provide the last described construction [i.e. the sliding door] in combination with an inflatable seal intermediate the door and the pressure vessel around the opening thereof." The relevant claims are for "inflatable seal means between said members for sealing said members in pressure tight relation around said opening when said seal is inflated". The body of the specification states that "it is preferable to provide the hollow resilient inflatable seal around the entire periphery groove or slot in the open end of the vessel walls". It provides for a connexion between the inflatable seal means and a source of fluid pressure and that there would be means of releasing the pressure and thus deflating the seal when it is desired to open the door.

It is necessary to examine what such evidence as was given discloses. The only witness was a Mr. Riley, a mechanical engineer, who was director of research and development of the respondent. He had been employed by the respondent since 1958 in the mechanical services division as an engineer, mechanical services, and later as engineer for the company until 1973. The respondent had a sterilizer division and since 1973 one of Mr. Riley's jobs had been manager of the sterilizer division. It does not appear that he had any direct responsibility for the sterilizer division before 1973, though no doubt he was aware of the nature of its activities.

Mr. Riley gave no evidence as to the state of common general knowledge in Australia in the relevant art as available to the skilled addressee, and indeed he did not qualify himself to do so. In cross-examination however he did give some evidence as to the problems associated with the Nugent patent in practice, which he said he had seen in the United States. Those defects may be summarized by saying that the gasket may not be sufficiently resilient, or become insufficiently resilient, and as a consequence may not retract out of the way of the door and become scuffed or damaged. In addition being an inflatable tube problems of breakage and leakage existed and the smallness of the tube imposed limits on the amount of pressure which could be placed on the door so as to effect the seal. He also said that the respondent company had an arrangement with an American group of companies, one of which owns the Nugent patent. He said that pursuant to that arrangement the defendant company had subsequently received from the American company drawings of an improved sterilizer incorporating the sliding door but having a solid resilient sealing gasket operated by fluid pressure and retracted by partial vacuum in the same manner as claimed in the patent in suit. This improvement was patented in the United States by another company in the same group, but the patent (McDonald's patent) reveals that the invention was made by different individual persons from the inventor named in the Nugent patent. That patent however was not published in Australia until after the priority date.

The body of the specification in the patent in suit does not refer to the problems associated with the kind of arrangement claimed in the Nugent patent but treats the prior art in Australia as comprising sterilizers with swinging doors which require heavy duty hinges and latches and having other disadvantages. The claims relate to a sterilizer fitted with a sliding door with the particular sealing method or device to which I have referred above. Mr. Riley's evidence was that the defendant company had manufactured sterilizers with hinged doors and in fact still made substantial numbers of them. He said that sterilizers in accordance with the Nugent patent had not been manufactured in Australia, and there is no evidence that any were imported.

That comprises the extent of information about the prior art in Australia which will be seen not to comprise any practical experience of sterilizers with sliding doors or the Nugent-type seal but to involve familiarity with hinged doors on sterilizers.

It was said on behalf of the respondent that the evidence showed that both Mr. Graham Hart (the managing director of the appellant company) and Mr. Riley had been in the United States and had seen sterilizers in accordance with the Nugent patent before the priority date of the patent in suit and it was further said that that demonstrated that such sterilizers formed part of the common general knowledge in the art in Australia. That submission is entirely misconceived because the fact that two individuals may have obtained knowledge abroad and come back to Australia (where they did not put it into operation) does not demonstrate that the knowledge is part of common general knowledge in the trade in Australia. What the expression "common general knowledge" refers to is that which is part of the ordinary equipment of all persons engaged in the relevant art, i.e. part of their general background knowledge which they put to use in the exercise of that branch of industry or manufacture. Accordingly the only material now relied on is the two patent specifications referred to by the trial judge.

In the course of argument counsel for the appellant was asked by the Chief Justice the following question: "You do not contest in this case that the terms of the Nugent patent ought to be looked at when deciding the question of obviousness, do you, seeing it had never been used in Australia?" He answered that question by saying, "That is so, sir". Although the question did not specifically refer to Stachiw's patent, the argument proceeded upon the basis that alleged paper anticipations might properly be looked at for the purpose of determining obviousness.

Because of that concession made by the appellant this is not a case in which it is necessary or indeed proper for this Court to deal with the point which was reserved by the Full Court in John McIlwraith Industries Ltd. v. Phillips [29] . It has been referred to in a number of cases in the original jurisdiction of the Court and dealt with on the basis that, until the Full Court deals with the matter, the decision of Williams J. in H.P.M. Industries Pty. Ltd. v. Gerard Industries Ltd. [30] should be followed: see Sunbeam Corporation v. Morphy-Richards (Australia) Pty. Ltd. [31] ; Universal Oil Products Co. v. Monsanto Co. [32] ; and Meyers Taylor Pty. Ltd. v. Vicarr Industries Ltd. [33] . It is not in the present case desirable to do more than note those cases and the decision of the House of Lords in Technograph Printed Circuits Ltd. v. Mills & Rockley (Electronics) Ltd. [34] without commenting on the matter further. The question for determination therefore is whether, upon the assumption that those prior paper publications may, when viewed alone, be treated as a basis for obviousness, they do in fact make this alleged invention, admittedly novel, one which was obvious.

1. (1958) 98 C.L.R. 529. 2. (1957) 98 C.L.R. 424. 3. (1961) 35 A.L.J.R. 212, at pp. 217-219. 4. (1972) 46 A.L.J.R. 658, at pp. 659-660. 5. (1977) 137 C.L.R. 228, at p. 236. 6. [1972] R.P.C. 346.

It is important to remember that the question is not whether it is now obvious to the Court but whether "at the relevant date it would have been obvious to the unimaginative skilled technician". It is also essential to remember the fundamental difference between novelty and obviousness as stated in Blanco White on Patents for Inventions, 4th ed. (1974), par. 4-220 as follows:

Since obviousness is a pure question of fact, the question to be asked in relation to a prior document becomes not (as with novelty): what is the effect of the information that this document gives when properly construed? But: What would this document in fact convey to those in the art? To which one must add the point already made, namely what would it convey to them at the relevant priority date.

It is not permissible to seek assistance in determining the question of whether a prior paper publication renders the claim for a patent obvious to investigate what would have been discovered if the proposal had been put in practice. In the present case the evidence shows that the prior Nugent proposal had never been manufactured in Australia and there is nothing to show that an example had been imported. It is true that Mr. Riley in evidence stated some of the disadvantages and in particular the rubbing which occurred between the sliding door and the inflated tube, but that he learnt in the United States. There is nothing in the evidence to show that he was aware of that defect at the time when he first saw the American drawings which corresponded to the appellant's invention.

It is also desirable to bear in mind the observation of Somervell L.J. in Cleveland Graphite Bronze Co. Ltd. v. Glazier Metal Co. Ltd. [35] where he said: "What is obvious to a reader must normally be obvious to the writer." In this connexion there is some significance in the fact that some years went by before that which is the substantial equivalent of the invention claimed by the appellant was claimed and patented in the United States, not by the original inventor of the Nugent patent, but by other persons, who one may assume to have been employed by or associated with another company in the same American group. Such a circumstance cannot be conclusive but it points towards, rather than away from, inventiveness.

In the present case the learned trial judge appears, with respect, to have paid insufficient attention to the feature which is central to claim 3 and which, though it is narrower in ambit than claim 1, the widest claim, adds a new feature which the evidence of Mr. Riley suggests is a significant advantage. In the absence of any expert evidence as to the common general knowledge in this particular field of manufacture, it does not appear that there is a sufficient basis for denying that at least that step has the relevant scintilla of invention. That is to say, there appears no adequate reason for regarding as obvious that which those who were associated with and working with the Nugent patent did not themselves perceive until some four years or so after the filing date of Nugent's patent (filed 9th June 1965), as is shown by the fact that McDonald's patent was filed in the United States in April 1970 (though not available for inspection in Australia until 3rd July 1973). The fact that a patent was granted in the United States is of itself of no great significance; what is significant is that the development which is the subject matter of the present patent was not the subject of an application for a United States' patent for more than four years after the filing of the application for Nugent's patent which is said to be the basis for this allegedly obvious development. No doubt there may be cases in which that which would be obvious to the appropriately skilled reader on the publication date in Australia may not necessarily have been obvious to the writer of the document at some earlier date, either in Australia or elsewhere, e.g. where there is shown to be some intervening circumstance which the later reader may be supposed to have known. When one is dealing with two paper proposals, of the practical operation of which nothing was known in Australia to those skilled in the trade, there seems no apparent reason why that which is now said to be obvious to the skilled reader in Australia was not obvious to the writer of the Nugent patent, so that he would have made claim to such an improvement. It is clear enough that it is regarded as an improvement, both from the oral evidence of Mr. Riley and from the fact that there is now some commercial demand for sterilizers according to the appellant's invention, whereas no sterilizers according to the Nugent patent were made or imported into Australia.

When dealing with the objection of obviousness it is always necessary to bear in mind that subsequent analysis of an invention in the light of prior objects or documents is not often helpful in resolving the question, because the benefit of hindsight obscures the nature of what would have to be foresight at the earlier date. In Commonwealth Industrial Cases Ltd. v. M.W.A. Holdings Pty. Ltd. [36] , Menzies J. quoted the following well-known passage from Lord Russell in Non-Drip Measure Co. Ltd. v. Stranger's Ltd. [37] :

Whether there has or has not been an inventive step in constructing a device for giving effect to an idea which when given effect to seems a simple idea which ought to or might have occurred to anyone, is often a matter of dispute. More especially is this the case when many integers of the new device are already known. Nothing is easier than to say, after the event, that the thing was obvious and involved no invention. The words of Fletcher Moulton L.J. (British Westinghouse Electric Manufacturing Co. v. Braulik [38] ) may well be called to mind in this connexion: "I confess" [he said] "that I view with suspicion arguments to the effect that a new combination, bringing with it new and important consequences in the shape of practical machines, is not an invention, because, when it has once been established, it is easy to show how it might be arrived at by starting from something known, and taking a series of apparently easy steps. This ex post facto analysis of invention is unfair to the inventors, and in my opinion it is not countenanced by English Patent Law." 1. (1970) 44 A.L.J.R. 385. 2. (1943) 60 R.P.C. 135, at p. 142. 3. (1910) 27 R.P.C. 209, at p. 230.

It appears that the learned trial judge was, perhaps through the absence of expert evidence, led into concentrating on claim 1. What he does is to compare the two prior patents with what he describes as the consistory clause of the patent in suit (which is equivalent to claim 1), omitting any reference to the use of a partial vacuum to retract the sealing gasket into the recess. He then deals with the differences between claim 1 and the subsequent claims and treats claims 2, 4 and 6 as being in effect no different. With respect, that ignores the fact that those claims incorporate the additional feature of claim 3. He speaks of claims 3 and 5 and treats the use of the partial vacuum as not being an inventive step and, mistakenly, as I think, says, "It is little more than the reverse cycle of the step involved in making the seal." There was certainly no evidence supporting such a finding. There are two quite separate steps involved. One is the application for force, i.e. pressure on the gasket to hold it firmly against the sliding door (which is claim 1). The other is not the mere release of that pressure but is the use of quite a different force, i.e. the creation of a partial vacuum in order to cause the sealing gasket wholly to retract into the channel (which is added by claim 3). He does not advert to the combination of the features of claim 1 with the use of the partial vacuum according to claim 3 as being the invention claimed in claim 3 and the following claims. There was no evidence before him which would suggest that it was part of the everyday equipment of persons in this field to observe that the use of a partial vacuum would be in practical terms effective to improve the device deemed to be known to him. It is no doubt easy enough to see now with the aid of hindsight that that is so.

The present case illustrates the wisdom of Lord Reid's observations in Technograph Printed Circuits Ltd. v. Mills and Rockley (Electronics) Ltd. [39] that, assuming that it is permissible to make a mosaic out of the relevant documents, "it must be a mosaic which can be put together by an unimaginative man with no inventive capacity" [40] . To this may be added a reference to his subsequent statement as to obviousness [41] : "On this matter the evidence of experts is generally valuable and often necessary."

1. [1972] R.P.C. 346. 2. [1972] R.P.C., at p. 355. 3. [1972] R.P.C., at p. 356.

This present case illustrates the difficulties with which a court is confronted in dealing with the issue of obviousness without any information as to the state of knowledge and technical information to be attributed to the man skilled in the trade at an earlier date, i.e. the priority date.

In relation to mere paper proposals it is also necessary to ask oneself the question why it should be obvious to alter the prior proposal at all. It is perhaps different where there are prior objects or prior user of a previous paper proposal because problems may have emerged in the course of the actual user, the solution to which may or may not be obvious. In the absence of any expert evidence suggesting some explanation as to why the original inventor did not think of it at the time of making his invention or even some suggested explanation by way of argument, it is difficult to maintain the proposition that the onus of proving no scintilla of invention has been discharged.

No argument was put to the Court that there was any difference as to obviousness between any of the claims, nor was there any challenge in respect of any claim to the trial judge's decision on novelty.

In the result therefore I am of opinion that the appeal should be allowed and the matter remitted to the trial judge for consideration of the questions of injunction and damages for infringement.