GB2080382A - Improvements relating to latch mechanisms - Google Patents

Abstract

A handle (6) is linked by co-operating flanges to a plate (14) by a bolt nose (2). The plate (14) can be moved independently by a lock mechanism (13) acting to rotate the plate (20) which will engage a pin (21) on the plate (14) to withdraw the bolt nose (2) into the body (1). The locking mechanism (13) incorporates a slot which, upon rotation, can be located in one or other of a pair of notches (28) in a hold plate associated with the plate (14) so as to lock the bolt in either the withdrawn or extended positions. A deadlatch nose (5), when withdrawn into the body (1), moves an associated plate (40) so as to allow a pin 48 to enter a notch so that a moulding (46) can rotate and allow a pin (47) to enter a notch (53) in the plate (14) (when the bolt nose (2) is extended) and thus hold the plate (14) against movement allowing the bolt nose to be withdrawn.

Description

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SPECIFICATION

Improvements Relating to Latch Mechanisms

This invention is concerned with latch mechanisms such as those which are used on 5 doors.

The conventional door latch mechanism takes many forms and, where security is important the construction can be quite intricate. Thus, the conventional cylinder night-latch or lock 10 mechanism incorporates a large number of parts requiring intricate assembly which cannot readily be mechanised.

It is an object of this invention to provide a latch mechanism which will provide good security . 15 and will have the conventional features of this type of door latch whilst providing advantages as to the method of operation and the degree of intricacy of construction.

According to one aspect of this invention there 20 is provided a latch mechanism comprising a casing within which is mounted a bolt which can slide from an extended position whereby it projects through the casing and a retracted position wherein it is at least partially withdrawn 25 into the casing, a drive shaft for rotary operation by a cylinder lock mechanism and carrying a drive member which may be rotated by the drive shaft to drive the bolt linearly from one position to the other, and an operating handle projecting from 30 the other side of the casing and linked with the bolt so as to move the bolt from one position to the other as the handle is slideably moved with respect to the casing.

It is greatly preferred that the drive member 35 and operating handle act independently upon the bolt, so that the cylinder lock does not have to drive the handle. Thus, the drive member and the operating handle may independently engage a plate carrying the bolt. For instance, the drive 40 member may be disposed to engage a pin projecting from the plate, whilst the operating handle is disposed to engage a flange projecting from the plate.

The plate itself may incorporate a groove 45 which will slide about the drive shaft as the bolt moves between its two positions. Also the bolt is ideally biased, such as by spring, to the extended position.

From a further aspect the invention provides a 50 latch mechanism comprising a casing within which is mounted a bolt which can slide from an extended position whereby it projects through the casing and a retracted position wherein it is at least partially withdrawn into the casing, an 55 operating handle projecting from the other side of the casing and linked with the bolt through a plate so as to move the bolt from one position to the other as the handle is slideably moved with respect to the casing, the plate having a slot 60 receiving a rotatable catch formed, in the region of the slot, with a groove cut in the side of the catch, or a projection from the side of the catch, the slot providing a track extending in the direction of movement of the plate and notches

65 extending at generally at right angles to the track such that, when the catch is in one attitude the track may slide about the formation of the catch, whilst the catch may be rotated to locate within one of the notches to prevent sliding of the plate. 70 In this latch mechanism two notches will normally be sufficient for holding the bolt in either of its two positions. The rotatable catch can be of circular cross-section and be formed with a semicircular groove therein, the notches having 75 correspondingly shaped curved and flat faces.

It is preferred that the catch should incorporate lugs which are a releasable snap fit into grooves in the body of the latch mechanism. These grooves will ideally be disposed to hold the catch 80 either in said one attitude or in the condition where it is fully engaged with one of the notches.

A still further aspect of the invention resides in a deadlatch mechanism comprising a casing within which are mounted a bolt and a deadlatch, 85 both of which can slide from an extended position whereby they project through the casing and retracted positions wherein each is at least partially withdrawn into the casing, the bolt and deadlatch being carried by a respective boltplate 90 and deadlatch plate, the bolt plate being movable by an operating member between it two positions, the deadlatch mechanism also incorporating a bolt securing member which is held by the deadlatch plate out of contact with 95 the bolt plate when the deadlatch is in the extended position but which is driven into the locking engagement with a part of the bolt plate so as to prevent movement of the bolt to the retracted position when the bolt is extended and 100 the deadlatch is in the retracted position, the operating member being operable to disengage the bolt securing member from the notch in the bolt plate.

Whilst the bolt securing member could be a 105 sliding member, it is preferred that it should take the form of a rotary member carrying first and second pins which can respectively engage with a notch in the bolt plate when the bolt is in the extended position and a notch in the deadlatch 110 plate when the deadlatch is in the retracted position. With such an arrangement the operating member can be positioned to be able to engage one of the pins to drive the first pin out of engagement with the notch of the bolt plate. 115 Ideally the bolt securing member is biased into the position of locking engagement with the part of the bolt plate, such biasing means comprising a spring arm carried by the bolt securing member. Also the deadlatch itself is preferably biased into 120 the extended position such as by a spring.

Also forming a feature of this invention is a latch hold mechanism comprising a casing within which is mounted a bolt which can slide from an extended position whereby it projects through the 125 casing and a retracted position wherein it is at least partially withdrawn into the casing, the bolt being carried by a plate incoporating a slot whose edge may be engaged by a notch at the end of a hold member, the hold member being biased to

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raise the notched end thereof free of the slot in the plate when the edge of the slot in the plate is disengaged from the notch, the hold member also incorporating an actuating portion which can be 5 pressed against the bias to allow the notch to engage with the edge of the slot in the plate.

In the preferred embodiment of latch hold mechanism the hold member is biased by integral spring-like arms thereof acting on part of the 10 casing, and the actuating portion is a button extending through the casing. Retaining means may be included for preventing the hold member from being removed from the casing. This retaining means can comprise projecting resilient 15 flaps on part of the hold member sliding within the casing, the casing carrying flanges against which the flaps will abut when the hold member is disengaged and biased away from the plate.

The invention does of course extend to a latch 20 mechanism incorporating any two or more of the main aspects as hereinbefore defined.

The invention may be performed in various ways and a preferred form of latch mechanism according to the invention will now be described 25 with reference to the accompanying drawings, in which:—

Figure 1 is a perspective view from above of the latch mechanism and staple;

Figure 2 is a perspective view from below of 30 the latch mechanism and staple;

Figure 3 is a cross section on line III—III of Figure 1, and Figures 3A and 3B show parts thereof;

Figure 4 is a cross section on line IV—IV of 35 Figure 3;

Figure 5 is a cross section on line V—V of Figure 3;

Figure 6 is a cross section on line VI—VI of Figure 3;

40 Figures 7 and 8 illustrate alternative states of a lock mechanism of the apparatus shown in Figures 3 to 6;

Figures 9 to 11 illustrate various conditions of the door bolt and deadlatch of the apparatus 45 shown in Figures 3 to 6; and

Figures 12 to 14 illustrate various conditions of a lock actuator forming part of the apparatus of Figures 3 to 6.

The latch mechanism illustrated in Figures 1 50 and 2 comprises a body 1 which houses parts for operating a bolt 2 which will be received within an opening 3 in a staple 4 which will be attached to a doorframe. The mechanism with the body 1 also operates a deadlatch nose 5. As will be 55 explained hereinafter the bolt 2 may be withdrawn by pulling a handle 6 in a sliding motion in the direction away from the staple 4. The handle 6 may be held in the open condition (fully retracted) by pressing a hold button 7, the 60 operation of which will be described later. The body 1 is attached to a back plate 8 which will be secured to the door and through which will pass a drive shaft 9 provided with a slot 10 to receive a tongue projecting from a cylinder lock which will 65 be secured through the door and may be operated from the outside of the door by a suitable key. A moulded portion 11 projecting from the body 1 will house both the hold button 7 and a key operated mechanism at 12 for locking the handle 6 in either of its two alternative positions (i.e. as shown or fully retracted). The actual construction of the key operated mechanism at 12 is not an essential part of the apparatus and may take many forms. Its purpose is to enable a lock moulding 13 (Figures 3 and 4) to be rotated between two alternative positions by use of key only.

The internal mechanism of the latch can be seen from Figures 3 to 6. The bolt nose 2 is fixed to a plate 14 by screws 15 which enter into a limb; 16 of the plate 14 located within a slot within the_ bolt nose 2. The bolt nose can be removed, turned; through 180° and secured in the new position so. that the latch mechanism can be used with both inwardly and outwardly opening doors. The plate 4 has a generally oblong slot 17 (with an enlargement 17A for receipt of the lock moulding 13 during initial assembly) which will slide about a cylindrical portion of the lock moulding 13 as the bolt nose is moved from the extended position shown to a retracted position within the body 1.

One method of moving the plate 14 is to rotate the drive shaft 9 (by key operation of the cylinder lock within the cylinder body 18 passing through the door 19). This causes an actuating plate 20 (shown in dashed outline in Figure 3) to be carried around with the drive shaft 9 so as to act on a pin 21 projecting from the plate 14 and thus cause the plate 14 to slide about the lock moulding 13. An alternative method of moving the plate 14 is to pull the handle 6 outwardly of the body 1. As can be seen from Figure 4 the handle 6 has, secured thereto, a stepped plate 22 carrying hold plate 23 from which projects a limb 70 (see also Figures 3A and 3B) which is received in a notch 71 in the plate 14. Also deformable lugs 74 mate within openings in the plate 22, whilst a continuous slot is formed in the plate 22 in line with the limb 70 which projects therethrough into the notch 71. The hold plate is kept down by the flange 72 which extends out from the lock moulding 13. Thus when the handle 6 is pulled outwardly the stepped plate 22 carries with it hold plate 23 and the plate 14 so as to withdraw the bolt nose 2 from the staple 4 secured to the doorframe 24. In order for this operation to be carried out the lock moulding 13 must be in a condition wherein it does not prevent the sliding movement of the stepped plate 22 and hold plate 23. Figure 3 shows a pair of pins 59 on the body 1 received in slots 60 in the stepped plate 22 which guide the sliding movement of the plate 22.

As can be seen from Figure 4 (and more clearly from Figures 7 and 8) the lock moulding 13 has a slot 25 formed therein leaving a semi-circular portion 26 which can be moved into or out of one of a pair of notches 27,28 in the hold plate 23. When the lock moulding is in the position illustrated in Figure 8 the stepped plate 22

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carrying the hold plate 23 can slide freely backwards and forwards about the portion 26 of the lock moulding 13. When the handle 6 is in the normal condition (into which it is biased by a spring arm 29 acting between a post 30 and the bolt nose 2) the lock moulding 13 can be rotated through 90° into the condition illustrated in Figure 7 so as to locate in a notch 27 in the hold plate 23 whereby the stepped plate 22 is locked against sliding movement. The lock moulding 13 carries a pair of lugs 61 which can snap into notches 62 formed in part of the body portion 11. Two sets of notches 62 at right angles to one another will be provided so as to hold the lock moulding 13 releasably in either of the two conditions illustrated in Figures 7 and 8. The deformable lugs 74 on the hold plate 23 will bend if undue force is applied to the handle 6 when the plate 22 is locked onto the lock moulding 13 by the hold plate 23 so that the lock itself cannot be forced by pulling the handle 6.

When the handle 6 is pulled out into the retracted position against the bias of the spring 29 the lock moulding 13 may again be rotated through 90° so that the portion 26 locates within the notch 28 thus holding the handle 6 (and the bolts nose 2) in the retracted position. It will however be appreciated that whenever the lock moulding 13 is latched into the notch 27 the plate 14 is still free to move about the lock moulding when the latch mechanism is operaated by a key inserted in the cylinder lock 18 to enable the bolt nose 2 to be withdrawn from the staple 4. A post 31 (Figure 3) acts as a stop limiting the movement of the head of the spring 29 and thus of the bolt nose 2. The engagement of the spring arm 29 against the post 31 prevents the deadlatch nose from entering wholly within the body 1 and thus ensures that the bolt nose 2 will not become displaced inside the body 1.

The handle 6 may be held in the retracted position temporarily by means of the hold button 7. As can be seen from Figure 6 the hold button 7 comprises a moulded body of resilient plastics material formed at its lower end with a notch 32. When the handle 6 has been withdrawn this notch 32 can locate about a reduced portion 33 of the stepped plate 22 as the tip 34 of the hold button 7 passes into an opening 35 due to pressure applied to the face of the button 7. The moulded hold button body incorporates a pair of resilient arms 36 which react against a part of the body moulded portion 11 of the body 1 and thus bias the hold button 7 outwardly of the portion 11. Integral flaps 37 which are biased slightly outwardly of the shaft 38 of the hold button 7 locate below steps (not shown) in a sleeve 39 through which the shaft 38 slides. The flaps 37 therefore limit the outward movement of the hold button 7 and will snap into place, during assembly, when the shaft 38 is initially inserted into the sleeve 39. A stop flange 37A limits the inward movement of the hold button 7 (especially during initial assembly). When the handle 6 is held in the retracted position by means of the hold button 7 it can be released by effecting a slight outward movement on the handle 6 whereupon the notch 32 becomes disengaged from the part 33 so that the hold button is moved clear of the part 33 by the action of the spring-like arms 36. Release of the handle 6 then results in the mechanism returning to the normal condition with the bolt nose 2 extended.

The latch mechanism also incorporates a deadlatch comprising the deadlatch nose 5 fixed to a deadlatch plate 40 (as shown in Figures 3 and 5). The deadlatch nose 5 is biased into the extending position shown in Figure 3 by means of a tension spring 41 mounted between a pillar 42 secured to the plate 40 and a post 43 forming part of the body 1. A slot 44 in the plate 40 allows the plate and deadlatch nose 5 to move between alternative positions about a pin 45. This pin 45 forms part of a deadlatch moulding 46 which carries two further upstanding pins 47 and 48, positioned either side of the plate 40, and a resilient spring-like arm 49 which reacts against a boss 50 on the body 1. The arm 49 therefore biases the deadlatch moulding to rotate about a mounting post 51 on the body 1, in the clockwise direction as viewed in Figure 3.

Operation of the deadlatch mechanism can be understood most clearly from Figures 9 to 14. (Wherein some features of the shape of the plate 14 have been omitted). When, as shown in Figure 9, the door is open so that the bolt nose 2 and deadlatch nose 5 are fully extended, the deadlatch moulding 46 is held in the same condition as illustrated in Figure 3 because the pin 48 is held against the side of the plate 40. As the door closes both the bolt nose 2 and the deadlatch nose 5 are pushed inwardly by the leading edge of the staple 4 (Figure 10) and, although the pin 48 is now free to move into notch 52 in the plate 40, it is prevented from doing so because the pin 47 is now held against the side of the plate 14 carrying the bolt nose 2. When the door is pushed fully home the bolt nose 2 enters the opening 3 in the staple 4 so that the plate 14 moves to the condition illustrated in Figure 11. The deadlatch nose 5 will still however be held in the retracted position by the body of the staple 4 so that the deadlatch moulding 46 can now rotate whereupon the pins 48 and 47 move respectively into the notch 52 and a notch 53 in the side of the plate 14 (the plate 22 has the corresponding notch 54 to the notch 53 in the plate 14 which also accommodates the pin 47 in this condition).

Any attempt to force the latch by inserting a knife or similar thin member between the body 1 and the staple 4 to try and push the bolt nose 2 inwardly will meet with failure since the bolt nose 2 will be locked in the extended position by the reaction of the pin 47 on the notched portion 53 of the plate 14. Also the deadlatch nose 5 cannot be forced inwardly any further in an attempt to cause the deadlatch moulding 46 to rotate back to the condition illustrated in Figures 9 and 10 since the pins 45 and 48 will respectively abut

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the ends of the slot 44 and the notch 52.

When the door is in the closed position as illustrated in Figure 11 the bolt 2 may still be unlatched either by pulling the handle 6 or 5 operating the cylinder lock 18 with a correct key from the outside of the door. Pulling of the handle 6 (assuming that the lock moulding 13 is in the condition shown in Figure 8) has the result that the chamfered edge 55 of the notched portion 54 10 acts as a cam surface on the pin 47 thus causing the deadlatch moulding 46 to rotate between the conditions illustrated in Figures 7 and 8. The Figure 8 condition of the deadlatch moulding 46 corresponds to that, for instance, of Figure 3 so 1 5 that the bolt nose can readily be withdrawn.

If a correct key is inserted into the cylinder lock 18 and rotated this will cause the actuating plate 20 to move firstly from the condition shown in Figure 12 to the condition shown in Figure 13. In 20 the process a face 56 of the actuating plate 20 acts as a cam face on the pin 47 to move the deadlatch moulding into the unlatched position. As the actuating plate 20 rotates further, an arm 57 of the actuating plate 20 reacts against the pin 25 21, thus carrying the plate 14 to the retracted position, and a curved surface 58 of the actuating plate continues to maintain the deadlatch moulding 46 in the unlatched condition (Figure 14).

30 The latch mechanism described in connection with the drawings can be seen to incorporate many operative features and advantages with respect to conventional latch mechanisms. The important features of the method of operation of 35 the mechanism will now be discussed briefly. As can be seen from the drawings, when the door is closed the bolt is automatically deadlocked thus providing substantial resistance against tampering. Furthermore, it is possible to prevent 40 the door from being opened from the inside unless a key is used to turn the lock moulding 13 from the locking position wherein the portion 26 is latched into the notch 27. The lock moulding will be operated from the inside by means of the 45 key operated mechanism 12. Furthermore, when the portion 26 is latched into the notch 27 with the door open, the door can still be closed so that the handle 6 is locked against movement. This feature is important for glass panelled doors and 50 the like where an intruder might be tempted to break the panel with a view to unlatching the lock from the inside.

The bolt 2 can be held in the withdrawn position in one of two ways. Firstly, it can be held 55 by the hold button 7 and can be readily released from this condition by pulling slightly on the handle 6 so that the hold button returns to the off position. In order to avoid the possibility of accidental lock-out, the bolt can be locked whilst 60 in the withdrawn position by locating the portion 26 within the notch 28 by actuating the key operated mechanism 12 with the handle 6 held in the pulled out condition. A small indentation can be provided in the staple region which is 65 contacted by the deadlatch nose 5, which will lightly hold the door closed when the bolt 2 is held in the withdrawn position.

As well as being of pleasing appearance the latch mechanism has certain advantages in operation compared with a cylinder night-latch (or rim latch) mechanism where the bolt can only be withdrawn by rotating a knob. The handle 6 provided can readily be grasped by persons with semi-arthritic fingers, or could even be pushed with the flat of the hand or an elbow. Furtheremore, the internal construction has been so designed that a minimal number of parts are employed, which parts can generally be formed by moulding or pressing. The method of assembly is relatively simple and thus lends itself to partial or full mechanisation. The cylinder lock within the cylinder body 18 may take many forms and may » indeed be of identical form (for use with the same key) as that which will be employed for the key operated mechanism 12.

Claims (24)

Claims

1. A latch mechanism comprising a casing within which is mounted a bolt which can slide between an extended position whereby it projects through the casing and a retracted position wherein it is at least partially withdrawn into the casing, a drive shaft for rotary operation by a cylinder lock mechanism and carrying a drive member which may be rotated by the drive shaft to drive the bolt linearly from one position to the other, and an operating handle projecting from the other side of the casing and linked with the bolt so as to move the bolt from the one position to the other as the handle is slideably moved with respect to the casing.

2. A latch mechanism according to claim 1, wherein the drive member and operating handle act independently upon the bolt.

3. A latch mechanism according to claim 2, wherein the drive member and the operating handle independently engage a plate carrying the bolt.

4. A latch mechanism as claimed in claim 3, wherein the plate incorporates a groove which will slide about the drive shaft as the bolt moves between its two positions.

5. A latch mechanism according to claim 3 or claim 4, wherein the drive member is disposed to engage a pin projecting from the plate. »

6. A latch mechanism according to any one of ^ claims 3 to 5, wherein the operating handle is disposed to engage a flange projecting from the , plate.

7. A latchmechanism according to any one of claims 1 to 6, wherein the bolt is biased, such as by a spring to the extended position.

8. A latch mechanism comprising a casing within which is mounted a bolt which can slide between an extended position whereby it projects through the casing and a retracted position wherein it is at least partially withdrawn into the casing, an operating handle projecting from the other side of the casing and linked with the bolt through a plate so as to move the bolt from one

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position to the other as the handle is slideably moved with respect to the casing, the plate having a slot receiving a rotatable catch formed, in the region of the slot, with a groove cut in the 5 side of the catch, or a projection from the side of the catch, the slot providing a track extending in the direction of movement of the plate and notches extending generally at right angles to the track such that, when the catch is in one attitude 10 the track may slide about the catch, the catch being rotatable from that attitude to locate within one of the notches to prevent sliding of the plate.

9. A latch mechanism according to claim 8, wherein two notches are provided for holding the

* 15 bolt in either of its two positions.

10. A latch mechanism according to claim 8 or claim 9, wherein the rotatable catch is of circular

^ cross section and is formed with a semi-circular groove therein, the notches having 20 correspondingly shaped curved and flat faces.

11. A latch mechanism according to any of claims 8 to 10, wherein the catch incorporates lugs which are a releasable snap fit into grooves in the body of the latch mechanism.

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12. A latch mechanism according to claim 11, wherein the grooves in the body of the latch mechanism are disposed to hold the catch either in said one attitude or in a condition where it is fully engaged with one of the notches. 30

13. A deadlatch mechanism comprising a casing within which are mounted a bolt and a deadlatch, both of which can slide between extended positions whereby they project through the casing and retracted positions wherein each is 35 at least partially withdrawn into the casing, the bolt and deadlatch being carried by a respective bolt plate and deadlatch plate, the bolt plate being movable by an operating member between its two positions, the deadlatch mechanism also 40 incorporating a bolt securing member which is held by the deadlatch plate out of engagement with the bolt plate when the deadlatch is in the extended position but which is driven into locking engagement with a part of the bolt plate so as to 45 prevent movement of the bolt to the retracted position when the bolt is extended and the deadlatch is in the retracted position, the operating member being operable to disengage the bolt securing member from engagement with « 50 the bolt plate.

14. A deadlatch mechanism according to claim 13, wherein the bolt securing member is a rotary member carrying first and second pins which can respectively engage with a notch in the bolt plate 55 when the bolt is in the extended position and a notch in the deadlatch plate when the deadlatch is in the retracted position.

1 5. A deadlatch mechanism according to claim 14, wherein the operating member is able to 60 engage one of the pins to drive the first pin out of engagement with the notch of the bolt plate.

16. A deadlatch mechanism according to any one of claims 13 to 15, wherein the bolt securing member is biased into the position of locking

65 engagement with the part of the bolt plate.

17. A deadlatch mechanism according to claim 1 6, wherein the biasing means is a spring arm carried by the bolt securing member.

18. A deadlatch mechanism according to any 70 one of claim 13 to 17, wherein the deadlatch is biased into the extended position, such as by a spring.

19. A latch hold mechanism comrising a casing within which is mounted a bolt which can slide

75 between an extended position whereby it projects through the casing and a retracted positron wherein it is at least partially withdrawn into the casing, the bolt being carried by a plate incorporating a slot whose edge may be engaged 80 by a notch at the end of a hold member, the hold member being biased to raise the notched end thereof free of the slot in the plate when the edge of the slot in the plate is disengaged from the notch, the hold member also incorporating an 85 actuating portion which can be pressed against the bias to allow the notch to engage with the edge of the slot in the plate.

20. A latch hold mechanism according to claim 19 wherein the hold member is biased by integral

90 spring-like arms thereof acting on part of the casing.

21. A latch hold mechanism according to claim 19 or claim 20, wherein the actuating portion is a button extending through the casing.

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22. A latch hold mechanism according to any one of claims 19 to 21, including retaining means for preventing the hold member from being removed from the casing.

23. A latch hold mechanism according to claim 100 22, wherein the retaining means comprises projecting resilient flaps on part of the hold member sliding within the casing, the casing carrying flanges against which the flaps will abut when the hold member is disengaged and biased • 105 away from the plate.

24. A latch mechanism according to any one of claims 1, 8, 13, and 19, and substantially as herein described with reference to the accompanying drawings.

Printed for Her Majesty's Stationery Office by the Courier Press, Leamington Spa, 1982. Published by the Patent Office, 25 Southampton Buildings, London, WC2A 1 AY, from which copies may be obtained.