Archibald Kenrick & Sons Ltd v Laird Security Hardware Ltd

This is an appeal from a decision of the Comptroller of Patents, acting through his Deputy Director, Mr Barford, who refused a proposed amendment to claims 1 and 2 of the patent in suit on the grounds that the invention as claimed in the proposed amended claims was not novel. The amendment was also opposed on the ground that the claims did not involve an inventive step. But in view of his conclusion on novelty, the Hearing Officer left that argument for another day, should it become necessary.

The patent in suit (GB Patent 2,297,796) relates to an improved locking mechanism. It seeks to overcome the widely-acknowledged problems of locking mechanisms for movable panels. In the case of sash windows, traditional locking mechanisms proved ineffective at delaying entry of experienced house-breakers who could use a jemmy to create a gap between the sash and its frame and prise open the sash window without the need to smash the window pane. Locking mechanisms using projecting bolts were known at the priority date. However, because the bolts projected permanently from the sash frame, there was necessarily an enlarged air gap between the lock frame part and the adjacent window part to allow closure of the sash. This enlarged air gap rendered the windows less safe and susceptible to forcing with a jemmy or similar tool. A number of prior art systems aimed at overcoming this problem are described at page 5 of the specification. It is not in dispute that the invention is patentable over these identified prior art systems. The object of the invention is to:

“provide a locking mechanism which includes an operating member and bolt means mounted to be moved by and with the operating member in which the bolt means is mounted to slide relative to the operating member.” (page 6 _5-8)

The patent goes on to explain:

“Preferably, the bolt means is slidable relative to the operating member in a second direction substantially perpendicular to the first direction of the operating member.” (page 8 _18-21)

The invention is described in Figures 3 to 11 of the patent. In the unlocked position, the bolts are fully enclosed within the volume of the housing which means that a minimal air gap is needed between that part of the window to which the lock is attached and that part of the frame to which the keeper is attached (page 13 _11-19). In the locked position, the locking bolts are fully engaged in the keeper and the movement of the frame relative to the panel is resisted or prevented. In this way, the invention increases the security of the fitted panel by reducing the likelihood of unauthorised entry, particularly by an intruder using a jemmy to force open the panel. The benefits of the invention are achieved by having the bolt mounted in such a way that it slides relative to the operating member. This enables the bolt to move in a different direction from its operating member (at the same time as it is being carried by the operating member) so that it can move out of the volume of the housing and slide into the keeper.

Claim 1 as unamended read:

“A locking mechanism which includes an operating member and bolt means mounted to be moved by and with the operating member in which the bolt means is mounted to slide relative to the operating member.”

Claim 2 as unamended read:

“A locking mechanism according to claim 1 in which the operating member is movable in a first direction, the mechanism having guide means for the bolt means adapted to move the bolt means at an angle to said first direction during movement of said member.”

The Respondent, Laird Security Hardware Limited, informed Kenrick of the existence of EP 0,411,271 (the “271 patent”) on 6 June 2003 in the course of correspondence about suspected infringement. Kenrick accepted that the invention as claimed in claim 1 was not novel in the light of the 271 patent and applied on 29 July 2003 to amend the claims of the patent in suit.

Claim 1, as proposed to be amended, reads (with the new words in italics):

“A locking mechanism adapted for mounting adjacent to an edge of a panel for use in locking the panel against movement relative to its frame, the locking means which includes including an operating member which is movable in a direction substantially parallel to the edge of the panel when the locking mechanism is mounted thereto and bolt means mounted to be moved by and with the operating member in which the bolt means is mounted to slide relative to the operating member, the bolt means being constrained to slide relative to the operating member in a direction substantially perpendicular to the direction of movement of the operating member”

Claim 2, as proposed to be amended, reads (with the new words in italics):

“A locking mechanism according to claim 1 having a housing in which the operating member is movable in a first direction relative to the housing, the mechanism having guide means for the bolt means adapted to move the bolt means relative to the housing at an angle to said first direction during movement of said member”

The Hearing Officer, at the invitation of the parties, decided the matter on the papers without oral argument. He issued his decision on 15 March 2006. He decided that the two claims, as proposed to be amended, were not novel in the light of the 271 patent; and refused the amendments.

It is not in dispute that the Hearing Officer applied the right general legal test for determining whether a patent is anticipated. Rather, Kenrick says that he failed to identify correctly the questions of construction of the patent in suit that were relevant to his decision.

The Hearing Officer identified what he considered to be the relevant questions in paragraph 42 of his decision:

“Laird argues that the amendments do not distinguish the claims from EP 0411271. Kenrick argues that the skilled person would answer “no” to the questions “does the bolt means of the prior art document move in a direction substantially perpendicular to the direction of movement of the operating member?” and “is the bolt means [of the prior document] constrained to slide relative to the operating member in a direction perpendicular to the direction of movement of the operating member?”

Mr Fernando submits that the Hearing Officer overlooked the wording “being constrained to slide relative to the operating member” in claim 1 as proposed to be amended. Since the Hearing Officer set out those words in formulating the questions he posed himself, I do not consider that he overlooked those words at this stage in his reasoning.

Having considered what was disclosed by the 271 patent the Hearing Officer concluded in paragraph 45:

“It seems to me to follow that in this embodiment the answer to both of Kenrick’s questions - “does the bolt means of the prior art document move in a direction substantially perpendicular to the direction of movement of the operating member?” and “is the bolt means [of the prior document] constrained to slide relative to the operating member in a direction perpendicular to the direction of movement of the operating member?” - is yes”.

Mr Fernando points to the summary in paragraph 47 in which the Hearing Officer says:

“This embodiment therefore seems to me to have all the features set out in amended claim 1 – namely a locking mechanism which can be mounted adjacent an edge of a panel and which has an operating member 37, 41 movable parallel to the edge of the panel, bolt means 44 mounted to be moved by and with the operating member, the bolt means being mounted to slide relative to the operating member, and being constrained (by the slot 49) to slide in a direction perpendicular to the direction of movement of the operating member.”

He points out (correctly) that this summary does not in terms refer to the bolt being constrained to slide relative to the operating member in a direction perpendicular to the direction of movement of the operating member. But since the Hearing Officer had come to precisely that conclusion two paragraphs earlier in his decision, the summary, in omitting that feature, is no more than a slip of the pen. It is, in my judgment, clear that the Hearing Officer asked and answered the right questions.

However, Mr Fernando has a second string to his bow. He says that even if the Hearing Officer answered the right question, the answer itself was wrong. He submits that in the 271 patent the bolt is not constrained to slide relative to the operating member in a direction substantially perpendicular to the operating member. In order to understand the argument and the Hearing Officer’s decision, it is necessary first to reproduce Figures 9 and 10 of the 271 patent.

The Hearing Officer’s reasoning on this question is set out in paragraph 44 of his decision as follows:

“Figures 9 and 10 of EP 0411271 show a lock which is operated by moving a bar 38 in a downward direction (as illustrated) parallel to a rail 36. The bar 38 moves a connecting piece 37, and the piece 37 has a pocket 39 containing a slotted link 41- all of which move in the same direction as the bar 38. A latch 44 is mounted to “slide” on the base 40 of the pocket 39 (page 16 lines 3 and 4 of the translation). The latch 44 has a pin 48 which carries a roller 50 engaging both the large slot in the link 41 and an L-shaped slot 49 formed in the base 43 of the lock. As the edge of the large slot in the link 41 engages the roller 50, the latch 44 is forced leftwards as shown in Figure 10 - that is to say in a direction perpendicular to the direction of movement of the parts 38, 39 - the latch being constrained to slide in that direction by the engagement of the roller 50 with the longer leg 49’ of the fixed L-shaped slot 49. The latch 44 continues to move in this direction until the roller 50 reaches the shorter leg 49’’’ of the L-shaped slot 49. Then a second link 55 is urged downwards by a spring 61 to push the latch 44 downwards - that is to say in a direction parallel to the direction of movement of the parts 38, 39 - the latch being constrained to slide in that direction by the engagement of the roller 50 with the shorter leg 49’’’ of the fixed L-shaped slot 49.”

This paragraph, which contains the nub of the Hearing Officer’s reasoning, does not refer to the relativity of movement in the mechanism described by the 271 patent. In essence Mr Fernando submits that the Hearing Officer did not accurately assess how the invention described in the 271 patent worked. In support of his submissions he produced a model which, he said, reproduced what was described in the 271 patent. It was agreed to be sufficient for the purposes of illustration. In the language of the patent in suit it is common ground that in the 271 patent connecting piece 37 is “the operating member” and latch 44 is the “bolt means”. The Hearing Officer did not concentrate on connecting piece 38 alone.

Pin 48 is at the tail of the latch and fixed to it. As the mechanism is operated the pin travels within the L-shaped slot. The long side of the L-shaped slot is at right angles to bar 38 and the short side is parallel with it. The two parts of the L-shaped slot are connected by an angle leg. This arrangement is described by the 271 patent as follows:

“The guide slot 49 has the angle leg 49’ running at right angles to the weather rail 36, which through the angle’s apex 49’’ adjacent to the weather rail 36 transforms into the shorter angle leg 49’’’ directed parallel to the weather rail. The diameter of the pin 48 is therefore adapted to the width of the guide slot 49. The link slot 41, however, has a greater width than the guide slot 49.”

The pin performs a two-phase movement: first along the long side and then, having reached the apex, down the short side of the L-shaped slot. Mr Fernando submits that in the first phase of movement, before the pin has travelled to the apex, the bolt means is travelling upwards and outwards relative to the operating member, the direction being defined by the angle of the upper wall (51) of the link slot. In the second phase of movement, the bolt means is travelling relative to the operating member in a direction parallel with the direction of the operating member, rather than perpendicular to it.

I begin with the first phase. The 271 patent describes the movement as follows:

“The forward locking of the latch 44 requires the moving bar 38 to be moved downwards. This causes the moving bar connecting piece 37 to be carried along also. The upper slot peripheral edge 51 presses against the roller body 50 which rotates on the pin 48 in conjunction with the fact that the latch 44 is displaced forward with the pin, i.e. moves out.”

Mr Fernando stresses the requirement in the claim as proposed to be amended that the bolt means must be “constrained to slide relative to the operating member in a direction substantially perpendicular to the direction of movement of the operating member.” This is not the same as being constrained to slide in a direction substantially perpendicular to the direction of movement of the operating member. The direction of movement of the operating member is parallel to the weather rail. The direction of movement of the bolt is at right angles (perpendicular) to the weather rail. Thus it can be said that the direction of movement of the bolt is perpendicular to the direction of movement of the operating member. But both these movements are movements relative to the overall housing of the lock. If the movement of the bolt is compared with the movement of the operating member, it can be seen that the bolt moves in two directions simultaneously, thus producing an angled trajectory. The trajectory follows the edge 51 of the upper slot. Take first the starting position of the bolt (most easily seen by considering the pin 48). In the horizontal plane it is close to the edge of the connecting piece furthest from the tail of the latch. In the vertical plane it is more or less equidistant from the top and bottom of the connecting piece. At the end of the first phase of movement (just as it comes to the apex of the L-shaped slot) the pin has moved across the connecting piece in the horizontal plane. But at the same time, the connecting piece has moved downwards. So, relative to the connecting piece, the pin has also moved upwards in the vertical plane; and it is now much closer to one end than the other. Accordingly, the pin has not moved perpendicularly, relative to the connecting piece: it has moved along an angled trajectory. The angle is defined by the upper edge 51 of the slot. According to the figure in the patent, the angle is of the order of 60^o.

Although the penny took some time to drop despite Mr Fernando’s lucid explanation, in my judgment as a matter of geometry this argument is correct. Mr Pritchard said that the practical locksmith would not be concerned with precise geometry or vector calculus. What was important was that the overall movement of the latch was at right angles to the overall movement of the connecting piece. However, I think that Mr Fernando was correct in submitting that this submission depended on looking at the movement of the latch and connecting piece respectively relative to the housing of the lock; and not to movement relative to the connecting piece itself. I also agree with him that in consequence the construction of amended claim 1 for which Mr Pritchard contended gave no effect to that integer of the claim that required the movement to be looked at relative to the operating member (the connecting piece in the 271 patent).

Mr Pritchard also argued that the relative movement did not have to be precisely perpendicular to the movement of the operating member: all that was required was that it should be “substantially” perpendicular. The word “substantially” is necessarily imprecise. However, in my judgment the degree of imprecision implicit in the word “substantial” does not extend as far as to encompass what is shown by the figure in the 271 patent. Mr Pritchard submitted that this did not matter. The 271 patent did not prescribe the dimensions of the lock. If the dimensions were adjusted, the angled trajectory would become shallower. But I think that Mr Fernando had the answer to this submission as well. The issue, at least for the moment, is one of lack of novelty, not lack of inventive step. A submission that the geometry of the lock depicted in the 271 patent could be adjusted belongs to the realm of obviousness rather than anticipation.

Mr Fernando also relies on a passage in the 271 patent which refers to the “linear lock-out of the latch at an obtuse angle to the movement of the moving bar”. He submits that the use of the word “obtuse” further confirms that the bolt means does not slide relative to the operating member in a direction substantially perpendicular to the direction of movement of the operating member. I think that this particular submission is ill-founded, because the passage in the specification on which Mr Fernando relies relates to a different embodiment of the invention claimed by the 271 patent (which includes a guide slot that does run at an obtuse angle to the moving bar).

However, for the reasons I have given in my judgment Mr Fernando is correct in submitting that in the first phase of movement the bolt means depicted in the 271 patent does not move, relative to the operating member, in a direction substantially perpendicular to the direction of movement of the operating member.

In addition, in its second phase it plainly moves in a direction parallel to the operating member. I do not consider that this second phase can be ignored. Without it the lock in the 271 patent would not work at all, because it is the downward movement of the latch that engages the lock. Mr Pritchard said that this did not matter, because the patent in suit also allows a parallel movement. The specification describes the movement as follows:

“Thus during the first part of the movement of the operating member 24b from the first or unlocking condition shown in Fig. 3, the bolt tip, in this embodiment bolt head 34b is caused to move outwardly and along the housing (at angle A) to its second (intermediate) position; during a second part of the movement of the operating member the bolt tip i.e. head, is caused [to] move substantially parallel with the operating member to its third or locking position shown in Fig. 4.”

Claim 13 claims:

“A locking mechanism according to claim 12 in which movement of the bolt means between its second and third positions is linear and substantially parallel to the said first direction of the operating member.”

Claim 13 is dependent on claim 12, and if one traces the dependencies, it can be seen that ultimately claim 13 is dependent on claim 1. Accordingly, Mr Pritchard says that claim 1 must encompass the parallel movement of the bolt tip. However, this submission also ignores the relativity of movement between the bolt and the operating member. Claim 13 is not concerned with the movement of the bolt relative to the direction of movement of the operating member. In the patent in suit, the bolt is fixed to the operating member. As the operating member moves laterally so the bolt moves with it. The bolt is only free to slide up and down within the operating member. Thus its only movement, relative to the operating member, is perpendicular (or substantially perpendicular).

Accordingly I have reached the conclusion that the Hearing Officer was wrong to refuse the amendment on the ground that the amended claim was anticipated. I think the error was understandable, since it coincided with my first impression on reading the patent in suit and the 271 patent. However, unlike me, the Hearing Officer did not have the benefit of Mr Fernando’s explanation. I will therefore allow the appeal and set aside the Hearing Officer’s decision. As I have said, the amendment is also opposed on the ground of lack of inventive step; and it is agreed that this question will be remitted to the Hearing Officer for further consideration.