Alan Nuttall Ltd v Fri-Jado UK Ltd & Anor

This is an appeal from Mr Peter Prescott QC, sitting as a deputy judge in the Patents Court in the Chancery Division of the High Court, the decision being [2008] EWHC 1311 (Pat). It concerns a patent, GB 2,348,697, which is registered in the name of Alan Nuttall Limited, the respondent, and it has a priority date of 22 December 1998. It relates to a self-service display cabinet in which food may be kept hot, for instance in supermarkets.

The respondent contended that a display cabinet known as Multi-deck Mark 2, manufactured by the appellants, Fri-Jado UK Limited and Fri-Jado BV, infringed the patent. The appellant denied this and counterclaimed for a determination that the patent was invalid on grounds of obviousness or insufficiency. The deputy judge found for the respondent on all three issues, ie that the Mark 2 infringed the patent, that the alleged invention disclosed in the patent was not obvious and that the patent was not insufficient. With the permission of the judge, the appellants appealed. Though some of the points ventilated are first instance and no longer in dispute, we are concerned with all three issues of infringement, obviousness and insufficiency.

I propose first to summarise briefly the teaching and the relevant claim of the patent, and explain the essence of Mark 2, largely by reference to the judgment below and, before turning to the three issues I have mentioned, to deal with what may be a core difference between the parties, resolution of which may greatly assist in resolving the issues of infringement, obviousness and insufficiency.

As the judge explained in paragraph 2 of his judgment, health regulations require that every part of the food in a display cabinet must be kept at a temperature of 63 degrees centigrade or higher. The traditional way to do that is to use hot plates or hot lamps. However, a disadvantage of this system is that the food is not heated evenly.

In that connection, as the judgment goes on to explain in paragraphs 10 to 16, the patent discloses a self-service cabinet, which is shown in figure 2 (which can be found on page 5 of the judgment included in paragraph 13). As the judge explained, the items of food are laid out on shelves shown in a main chamber. The cabinet does not have a front door. Instead it has an air curtain. The customer puts his hand through the air curtain in order to pick up an item of food. An air curtain is a rising or, as in this case, a falling curtain of air. In the case of this alleged invention it stops the hot air inside the cabinet from leaking out, and it stops cool ambient air from getting in. Air curtains as such were well-known in other contexts. For instance they were used in refrigerated display cabinets. In the case of such cabinets, chilled air comes out of a sort of grille at the top and is sucked in by another grille at the bottom. The display cabinet in the case of the alleged invention, as shown in the figure I have mentioned, is equipped with two air pumps, a pump at the bottom and a centrifugal fan at the top. The lower pump drives air over a heater and the heated air then goes up a duct. The duct is really a space between the back wall of the cabinet and the perforated metal skin.

Air that is going up this duct therefore has two possible flow paths. The first possible flow path is an escape sideways through the perforations of the duct and hence into the main part of the cabinet where the food is kept. There are baffles which help deflect the air downwards and encourage the flow of heated air around the food items. The air that is near the top of the next chamber is sucked upwards by the upper fan, which helps even heating of all the food items on the top shelf.

The alternative flow path for the air is to go all the way up to the top of the duct until it meets a barrier and thence into a chamber above the main part of the cabinet. The fan at the top draws in air and blows it into a compartment at the top. From there the air passes between two parallel fins downwards, thereby forming the air curtain. At the bottom of the air curtain the air is recirculated by the lower pump. So excess air in the main chamber will also be inducted by the air curtain.

As the judge explained, some of the hot air in the upper region will rise by natural convection and go into the space at the top, which is described as a “collection zone” and the air that accumulates there constitutes a kind of reservoir that can feed the air curtain for a short time if the air coming through the duct is interrupted.

The only claim of the patent which is relevant for present purposes is Claim 1, which, like the judge, I will divide into seven integers.

“(1)

A heated food storage and display cabinet comprising an open fronted chamber in which packs of food can be stored,

(2)

an upwardly extending enclosed air duct having a plurality of outlets over a substantial length of the duct leading from the duct to the chamber,

(3)

a first flow inducing means for directing air upwardly through the duct

(4)

and a second flow inducing means for producing a curtain of air which is directed across the open front of the chamber,

(5)

and heater means,

(6)

the first flow inducing means causing the air to pass over the heater means, through the duct passing through the outlets and into the chamber

(7)

and the second flow inducing means being arranged to draw air from the upper end of the chamber and use it in the formation of an air curtain across the open front of the chamber.”

I turn now to Mark 2, the allegedly infringing product of the appellants. This also has an air curtain instead of a front door, but the air curtain moves upwards not downwards, the air being driven by a fan in the lower part of the cabinet. After reaching the top of the air curtain, the air is drawn down through ducts provided for that purpose and is then sucked in by the fan. Again, there are drawings of Mark 2, which are included in paragraph 21 of the judgment below.

In Mark 2, hot air is emitted to the main chamber of the cabinet and hot air is also driven by means of a fan, but hot air is also driven by a second fan and such hot air is caused to flow up a duct inside the back of the cabinet and hence into the shelves which are hollow. The shelves are provided with holes, so the air is driven into the main chamber through the shelves. Excess air in the main chamber will be inducted into the air curtain, hence removed. Additionally, the air that emerges from the hollow shelves is driven downwards and hence onto the food item beneath.

So much then for the very brief summary of the patent and the allegedly infringing Mark 2. Before I turn to the specific issues, I shall deal with the core difference between the parties, to which I made reference. It is a core difference which is particularly apparent in the skeleton arguments which we received ahead of the hearing, but it also played a part, albeit not such a primary part, in the oral argument. In a sense the difference centres round the judge’s so-called “thumbnail sketch” of the principle that is taught by the patent in suit. He gave that thumbnail sketch in paragraphs 70 and 76 of his judgment and expressed it in these terms:

“A hot air display cabinet with two fans, one for driving hot air over food items via openings in a duct, the other for forming an air curtain across an open front and for drawing air from the top part of the compartment where the food is stored.”

A little later he expressed himself in these terms in paragraph 77:

“…one fan for controlling the air curtain circuit and another fan to control the food-warming circuit.”

According to the appellants this is something of a distortion of what the patent teaches or even claims, because the judge’s formulation implies that there are two air circuits while, on a fair reading and analysis of the teaching of the patent, there is only one such circuit. The difference between two circuits or one circuit is in a sense slightly artificial because on any view, if there are circuits which inter-relate, one can argue about whether there are two circuits or one circuit. Indeed that is even true in relation to Mark 2, but, in my view, in agreement with the respondent, the judge was right to conclude that the patented invention involved, and the patent properly interpreted taught two separate although by no means independent air circuits.

In the first place there are integers (3) and (4) and integers (6) and (7) of Claim 1, which to my mind make it clear that there are two separate “flow inducing means”, and that each of them serves to drive air in different directions, although it is clear that the two flows are connected. Secondly, the point is reinforced by passages in the patent to which I have not so far referred. On page 9 the first air flow is described in these terms:

“The pump [which I interpose is the lower pump] draws air through the front perforated sheet and into the inlet. The air is then blown by the pump through the outlet over heating elements through the perforations in the adjacent part of the perforated skin and into the air duct. The heated air is driven upwards through the duct and the upper end of the duct as the closure of the heated air is forced through the perforations then the front skin of the door and into the chambers indicated by arrows.”

The second air flow is described at page 10 of the patent:

“The operation of the fan [I interpose the upper fan] draws some of the air near the top of the chamber upwards, thereby encouraging airflow at the top of the chamber beneficial for maintaining the temperature of food packs on the top shelf and through perforations in the sheet which are immediately beneath the fan. The fan forces air into the compartment and through the outlet. The air driven through the outlet and past the fins is forced downwards and slightly inwards by virtue of the inclination of the fins. The air entering the compartment through the perforations in the skin has a component of outward movement towards the open front of the chamber.”

The passage then goes on to refer to the inwards directions of the air.

Of course when both fans are on, as the respondent accepts, the two circuits are brought together, and this again is explained in a passage in the patent towards the bottom of page 10, from which I think it is unnecessary to quote.

In any event the idea that the two systems must, as it were, operate as one system is questionable by virtue of the fact that this is not a closed loop system. Additionally, as Mr Fernando for the respondent pointed out, the patent teaches that a pulsing system is possible in relation to one of the pumps (the lower pump) on page 11 of the patent, which would not be so appropriate for the air curtain, and this emphasises again that the two systems are separate, albeit, as I say, not wholly independent when they are both functioning as the patent explains.

Additionally there is the evidence of Mr James, the respondents' expert, which supports the notion that there are two systems. He referred in his evidence to the:

“need to create a) a flow of hot air over all the food packages … throughout … and then through the top … and b) an independent air flow system (emphasis added) to produce an air curtain”

Additionally, in his oral evidence Mr James made frequent reference to the existence of two air flows.

So far as the appellant’s expert, Mr Gigiel, is concerned, he accepted in his report that if the upper fan was switched off, there would be no air curtain, which tends to support the fact that there are two systems.

In paragraph 79 of his judgment the judge commented on the absence of “fluid dynamics calculations or experiments” on the issue of whether one could satisfactorily control air flows with only one fan. However, he concluded that there was “a distinct advantage in having the above described two-fan concept”. It is true that in one passage in his evidence Mr Gigiel could be seen to be suggesting that there was a single flow but that is, as I see it, the only evidence the other way. It is certainly not nearly enough to persuade me that the teaching of the patent involves only one air circuit.

I now turn to the issue of obviousness. The judge was faced with a number of items which were alleged to render the teaching of the patent as obvious. Only three have been pursued before us, two of them items of prior art and common general knowledge. So far as obviousness generally is concerned, there is no doubt that the judge directed himself correctly, namely in accordance with the approach promulgated by Jacob LJ in Pozzoli SPA v BDMO SA & Moulage Industriel de Perseigne [2007] EWCA Civ 588 at paragraph 23, and it is clear that he took the view that the obviousness attack failed. Accordingly, at least in principle, the appellants face an uphill task in their attempt to overturn his conclusion on this issue: obviousness is very much a question for the trial judge, and, where he has directed himself correctly, an appellate court should only interfere if he reached a decision which was plainly untenable and which he could not have reached.

The first specific item of prior art it is convenient to consider is US Patent No. 4,089,322, published in 1978 and known as Guibert. This disclosed a heated display cabinet with an air curtain. It is circular in shape, so it can be approached from all directions, and it only has one flue. The only drawing attached to Guibert which I need refer to is that reproduced in paragraph 74 of the judgment below. In the light of the evidence accepted by the judge and agreed to by Mr Gigiel, it disclosed a cabinet which, if it had been made, would have been very noisy and would have proved very difficult to make work. In practice, as the judge put it at paragraph 75, a huge amount of energy would be required, implying a very large air flow, and it might be very difficult, if not impossible, to control such an apparatus without breaching the air curtain or burning the customer’s hands. A brief description of Guibert is to be found in paragraph 74 of the judgment:

“Heated air is driven upwards by a fan and hence into a tapered annular gap defined by a perforated cylinder and an adjustable cone device. Thus some of the air passes under pressure through the perforations, to heat the food items that are displayed on the shelves as shown in the drawing. The rest of the air passes up into a gap between two hemispherical domes and hence downwards to form the air curtain.”

In the light of the evidence to which we were taken, the effect of which is summarised in the brief passage I have quoted, I can see a very powerful argument indeed for saying what the respondent said before the judge and repeats by way of a Respondent’s Notice in this court, namely that this was self-evidently a wholly impractical device which the notional skilled man in 1998 would never have taken seriously or thought worth taking forward. However, the judge was ultimately not impressed with that point, saying that the skilled reader would not be compelled to be so ambitious as to assume that Guibert would have to be performed in full, and he went on to say:

“He might be looking for an apparatus that would merely keep food warm”,

which is part of what Guibert taught. He continued:

“He might not need to pack his food items at all tightly.”

Although, as I say, I can see a powerful argument to support what the respondents say on the appeal by way of cross-appeal, I would be reluctant to disturb the judge’s conclusion on what was ultimately a matter of inference and judgment in the light of the evidence. Equally, however, I find it difficult to accept that it would be right to interfere with the judge’s conclusion that the patent is not obvious over Guibert on the ground that, and I quote from the judgment:

“…it did not occur to Guibert to use one fan for controlling the air curtain circuit and another fan to control the food-warming circuit.”

The judge accepted that there was “a distinct advantage in having the above described two-fan arrangement”, as I have quoted earlier. This was supported by the evidence of Mr James that the two-fan system had the benefit of collecting the air from the top of the chamber, a view which also derived some support from Mr Gigiel.

In my view, even accepting, therefore, that Guibert would have been taken seriously by the notional skilled person in 1998, it seems to me that the point being made by the judge, namely that using an additional fan for controlling the air curtain as opposed to the fan controlling the food warming circuit, was original and an advantage, and, although Mr Wilson QC in his strong and clear submissions on behalf of the appellants invites us to hold otherwise and says that the addition of a fan for this purpose was obvious over Guibert, I am unpersuaded that we should depart from the conclusion reached by the judge who, as it is accepted, appeared properly to direct himself.

The second item of prior art which is pressed before us, over which it is said that the patent is obvious, is another United States Patent, No. 2,993,349, published in 1961 and known as Detwiler. As the judge explained in paragraph 81 of his judgment, which includes a drawing from Detwiler, it discloses a refrigerated display cabinet which is open at the front, so that customers can access the food products through an air curtain. It has a door at the back which can be opened so that the staff can insert food items in order to stop the cold air blowing out when the door is opened. There is a second curtain at the back. The judge said at paragraph 82:

“The air curtains are driven by [two] fans. When the back door of the cabinet is closed air passes up the back of the cabinet through a pair of vertical flues … when the back door is opened this air continues to rise acting as an air curtain the flues are in open and direct communication with the spaces between the shelves of the cabinet.”

It was argued below on behalf of the respondent that Detwiler was not relevant prior art because it was concerned with a cold rather than a hot cabinet. The judge seems to have ducked this issue in that he said in paragraph 84:

“I will assume that the person skilled in the art who read Detwiler in 1998 was interested in designing a display cabinet for keeping food hot.”

The point is not entirely clear although one sees the force of the point made by Mr Wilson that cold and hot are, as it were, opposite sides of the same coin, but there was an issue as to whether the notional skilled man was, as the appellants said, somebody who was interested in hot and cold cabinets or, as the judge found, somebody who was primarily interested in hot cabinets. In those circumstances it might have been helpful if the judge had made an express finding on the issue.

However, assuming in the appellants’ favour (and, in the light of Mr Wilson’s argument, I can see a powerful argument to support this) that the judge was there making a finding rather than an assumption, the appellants have the difficulty that the judge found in paragraph 84 that the skilled man reading Detwiler:

“…would not have arrived within Claim 1 of the patent in suit. It [Detwiler] would lack the duct with a plurality of outlets over a substantial length thereof leading from the duct to the chamber where packs of food are stored. [integer (2)] For promotion of heat transfer in relation to the food items Detwiler has a different arrangement in mind. It is that the two air curtains flow in opposite directions and hence set up rotating air vortices, creating turbulence. I do not know if that would be effective. Be that as it may, in my judgment the duct concept would not be suggested to the ordinary, unimaginative skilled man who read Detwiler.

The patent itself discusses Detwiler and on page 2 says this about it:

“The open front of the flue does not have a guarantee that a sufficient amount of cooled air will reach the food stored at the top of the cabinet or that the flow of air would be reasonably even throughout. Moreover any food overhanging the back of the shelves so as to project into the cabinet will interfere with and upset the flow of air along the flue [sic]. Moreover a flow path to the second blower does not encourage air to blow over food at the other end of the cabinet, so no even air flow or air in the top of the chamber, which is what the specification of the patent claimed to reveal over Detwiler.”

The fact that a flue can be said to be like a duct with such large holes that the duct has no wall is an ingenious point made by Mr Wilson and, at least in theory, it has a considerable force. However, it does not seem to undermine the judge’s conclusion, which is essentially a practical question about whether the skilled person reading Detwiler would have thought of a duct with holes rather than a flue. Quite apart from that, there is the point about air turbulence made by the judge: it might well have specifically put off the skilled person from, as it were, jumping from Detwiler to Claim 1 and to the teaching of the patent. It seems to me that it is just the sort of question that is for the judge and not for us and, although one might think, listening to Mr Wilson’s argument, that if one had been sitting at first instance, one might have reached the opposite conclusion, that is not the issue before us. Indeed, it would be unfair to give either side the impression that that was my view, because Mr Fernando did not go down the route of putting forward the arguments that he would have put forward at first instance in answer to what Mr Wilson said, rightly recognising that this is an appeal and not first instance. Quite apart from this, it seems to me that there is force in the additional point that the two-fan arrangement in Detwiler must be seen in the context of there being two doors and two air curtains, a very different system, and therefore directed to a very different purpose, on the face of it, to the unimaginative but skilled reader, from that envisaged in the present patent.

So far as the third aspect of obviousness is concerned, common general knowledge, this was, as the judge said, a standard refrigerated display cabinet with an air curtain. It is questionable whether common general knowledge was actually relied on below as a ground for an obviousness case. It does not appear to have formed part of Mr Gigiel’s report in the lengthy section 3.6 headed “Did the patent involve an inventive step?”. However, if one takes another passage in his discussion about common general knowledge, in section 3.2 of his report, one can just about identify a contention that the patent is obvious over common general knowledge. It is fair to say that it may make the classic error of adding two successive allegations of obviousness. But there is another problem about the obviousness claim over common general knowledge. In their written opening to which Mr Fernando took us, the appellants’ counsel below relied on the standard refrigerated display unit, together with another piece of prior art, as founding a claim of obviousness. The other piece of prior art, which I do not need to go into, was subsequently abandoned, which appeared to leave the argued case on common general knowledge, or at least the opened case on common general knowledge, flailing in the water. Furthermore, the obviousness case based on common general knowledge is rather academic. As Mr Wilson realistically accepted, if obviousness over the two specific items of prior art failed, obviousness over common general knowledge must also fail. At least on a superficial view, it seems to me that that must be right. Given that common general knowledge is a cold cabinet with one fan and the two specific items of prior art are (a) a hot cabinet with one fan and (b) a cold cabinet with two fans, it seems unrealistic to think that common general knowledge, a cold cabinet with one fan, could be obvious over a hot cabinet with two fans.

I turn to infringement. The appellants rely on two integers of Claim 1, which they say that the Mark 2 does not infringe. The first point is that the patent has the hot air curtain descending but it is rising in Mark 2. Secondly, it is said that while the way heat is transferred in the patent is by convection, whereas it is by conduction as well as convection in Mark 2.

First then, there is integer (2), which, it will be recalled, refers to an upwardly extending enclosed air duct having a plurality of outlets over a substantial length of the duct leading from the duct to the chamber. The appellants argue that the phrase requires the outlets in the duct to be spaced so as to permit a flow of air from the duct, in particular on to the air space above the shelves, so, if that part of the duct which is above the top shelf in the cabinet has no holes, there is no infringement. It seems to me that that is a very difficult argument to sustain. As a matter of ordinary language, a “substantial length of the duct” does not refer to a specific part of the duct. Provided one can say as a matter of ordinary English that there is a plurality of outlets over a substantial length of the duct, the fact that the top 10 per cent of the duct, or the bottom 20 per cent of the duct, or the middle 15 per cent of the duct, does not have outlets does not prevent a substantial length of the duct having it.

Of course one cannot construe integer (2) on its own, as there is no such thing as an acontexual meaning, and one has to look at the context. However, that does not mean that one ignores the words completely. One has to give the words a meaning that they naturally bear, albeit one that they bear in their context.

It is true that the teaching of the patent in the specification describes how it is desirable to have hot air coming into the cabinet in the top area above all, but that does not seem to me to lead to the conclusion that the draftsman of the patent was limiting the patent or his claimed monopoly only to those cabinets which had holes in the duct above the top shelf. A moment’s consideration would show how unrealistic that is. The fact that the system would not work so well if it did not have holes above the top shelf would not be a reason for excluding it from the ambit of the patent. Furthermore, as Mr Wilson accepted, if one had wire shelves rather than solid shelves the need for holes above the shelf would not be self-evident. Further, as Mr Fernando asked, what if there was a shelf very near the ceiling of the cabinet with very little space above it simply with a few small items to be stocked? Can it really have been thought that this was intended to be excluded from the ambit of the patent? I think not.

As the judge put it, the contention ultimately failed because “it involves going beyond the purpose of construction”. It simply involves ignoring the natural meaning of the words, and giving them a meaning which, at best, can be said to be indicated as a possibility by the patent. One could understand it if the claim had been drafted so as to require some holes to be above the top shelf, but it seems to me it would have been an odd and unnecessarily self-limiting provision to include. In those circumstances I think the judge was right to conclude that integer (2) is satisfied by Mark 2. As Jacob LJ put it in argument, taking the invention and making it work less well does not prevent one from infringing a patent.

I turn to the other integer which is said not to be infringed, integer (7). This integer, it will be recalled , says this :

“the second flow inducing means being arranged to draw air from the upper end of the chamber and use it in the formation of an air curtain across the open front of the chamber.”

Fastening on the word “draw”, the appellants say that in Mark 2 there is no drawing of air from the upper end of the chamber. The judge accepted that, reading the specification, the primary purpose of this feature was to draw air from the upper end of the chamber, so that it promoted the flow of heated air over the uppermost food items. However, having gone that far with the appellants’ case, he said that there was “no limitation concerning how it was done” and that “Claim 1 should be construed accordingly”.

Essentially the appellants’ arguments amount to this, that Mark 2 involves no drawing of air out of the upper part of the chamber, in that the air from the upper part of the chamber may be, to use Mr Wilson’s happy word, entrained, by the effect of being sucked out through the means of the upward flow of air through the air curtain but that is not being drawn. Again, in agreement with the judge, I think that that gives too limited a meaning to the concept of drawing air. Air, as Mr Fernando said, is clearly drawn out through these means on the second flow inducing means, and the fact that it is indirect does not alter the fact that it achieves this end. It is not as if the air in the upper part of the Mark 2 cabinet is stagnant. It is moving, and it is drawn into the ascending air flow rather than, as in the primary purpose of the patent, ascending.

That then deals with infringement and leads neatly to insufficiency, because in the end the insufficiency argument came down to this. Mark 2 has a rising air curtain whereas the patent primarily teaches a falling air curtain. It does not actually spell out that the curtain has to be falling, as Mr Wilson accepts, although it implies that the curtain should fall as: (a) it involves a circulation system under which the air goes up the back and this strongly suggests that it would tend to come down the front; and (b) it teaches against more pipework and ductwork than is necessary.

Mr Wilson suggested that the insufficiency argument might also be characterised as a fair basis argument. This is not a case where it is necessary to consider whether, and if so, to what extent, fair basis is still a relevant concept of the law of patents, nor is it necessary to consider the extent to which so-called “Biogen insufficiency” can be relied on. Indeed, it is unnecessary to embark on any examination of the law of insufficiency. Whether viewed as insufficiency or lack of fair basis, it seems to me that this final argument raised by the appellants must be rejected on any view. There is no suggestion that the ordinary skilled person to whom a patent is addressed would have had any difficulty following its teaching and applying it to a hot food display cabinet where the air curtain went upwards rather than downwards. Indeed the evidence of Mr James suggested that there would be no problem in that correction. The fact that the draftsman of the patent might have regarded such a design as unattractive is no reason for concluding that such a design is either excluded from the ambit of the patent or that the patent is somehow invalid if it extends to such a design.

In those circumstances, for my part, having considered the various arguments raised on this appeal, and with gratitude to the parties for the relatively clear and expeditious way in which they presented their arguments, I would dismiss this appeal.

I agree. There is no point in my giving a separate judgment. This case involved no question or principle of law.

I also agree.