GB2123478A - Locks - Google Patents

Abstract

A mechanically reprogrammable lock includes a set of pivotal levers 8 controlling respective split plungers 6 which normally lock a bolt-operator 4. The levers 8 are pivoted on respective cams 15, by insertion of a notched key card 16, to set the plungers 6 in unlocking positions. To reprogramme the lock the cams 15 are rotated to new positions to change the pivot points for respective levers 8, so that a newly coded key card is then needed to pivot the levers 8 the required amount to set the plungers 6 in their unlocking positions. A mechanism for automatically adjusting the cams 15 in response to the insertion of a newly coded correct key is described. <IMAGE>

Description

SPECIFICATION Locks The present invention relates to locks, and more particularly to mechanically reprogrammable locks.

Hotels and other premises having a rapid turnover of occupants or staff face a continual security problem from the loss, theft or duplication of door keys. The only practical remedy to this problem with conventional lock systems is the periodic removal and replacement of the cylinder assemblies or other key-recognition mechanisms of the various locks, but this is both time consuming and expensive and, in the case of hotel rooms for example, cannot provide an adequate assurance of security unless carried out for each individual let. A number of electronically-based card-operated locking systems are available which, in the hotel context, seek to alleviate this problem by enabling the lock combinations to be changed for each successive guest so that the retention or theft of individual keys becomes less serious.Such systems are, however, relatively expensive and involve the problem of providing a reliable electrical power supply to each individual lock and in ensuring that security will not be compromised, by a failure of the power supply.

Accordingly the present invention is concerned to provide a form of lock which likewise enables frequent combination changes to be made, in an inexpensive and rapid manner, but without depending for its operation on an electrical power supply.

According to the invention a mechanically reprogrammable lock comprises a set of pivotal levers to control locking and unlocking, the levers being biased normally into a locking condition but being pivotably into an unlocking condition by means of a correctly coded key; and wherein the levers are pivotable upon respective cams which are selectively adjustable in their rotational positions thereby to change the positions of the pivot points for the respective levers so that a correspondingly newly coded key is required in order to pivot the levers to the unlocking condition.

The key for such a lock may be in the form of a card which is simply inserted into a slot of the device to unlock, the key having a profiled leading edge respective portions of which are arranged to engage respective levers (whether directly or indirectly) to pivot the same by the amounts necessary to establish said unlocking condition.

Reprogramming of such a lock by rotation of the cams can be achieved by various means, including the simple indexing of the cams by hand in an arrangement which provides for suitable access to the cams by authorised personnel (only).

However, an important feature of the invention is an arrangement whereby the first insertion of a newly coded key is itself effective to change the combination of the lock to suit that new key, through the operation of a reprogramming mechanism embodied in the lock, e.g. where there exists a predetermined relationship between the existing and new key codes and the reprogramming mechanism is operable to modify the existing combination in a predetermined manner to arrive at the new combination corresponding to the new key code. In such an arrangement the reprogramming mechanism may be operated, on the first insertion of the new key, by a further portion of the key separate from the coded portion thereof and the associated unlocking operation may be effective to modify that further portion of the key so that subsequent insertions of the same key will have no further reprogramming effect.

The lock may further provide a facility for unlocking by either one of two correct keys which can be regarded as "servant" and "master" keys (or "guest" and "master" keys in the hotel context), where the lock combinations for the two keys differ and furthermore may each be reprogrammed independently of the other. Such a lock may comprise second cams for respective levers where such levers are pivotable on the respective first-mentioned cams, by the second ("master") key but not by the first ("servant" or "guest") key, to positions in which they engage the respective second cams and pivot thereon (thereby disengaging from the first cams) to a condition equivalent to the aforesaid unlocking condition.

These and other features of the present invention will now be more particularly described with reference to the accompanying schematic drawings of an illustrative example thereof, and wherein: Figure 1 is a vertical section through a lock in accordance with the invention as installed in a door; Figure 2 is a front elevation view of parts of the lock of Figure 1 and the associated operating mechanism; Figure 3 is a plan view of a key card for use with the lock; and Figure 4 is a sectional view of the lock, on a plane parallel to that of Figure 1, showing part of a reprogramming mechanism.

Referring to Figures 1 and 2, the lock is shown installed in a room door 1. The door is equipped with a spring bolt 2 which must be withdrawn to the right (in the sense of Figure 2) to permit the door to be opened. From inside the room the bolt can be withdrawn at any time at the selection of the occupant by any convenient, direct means (not shown) and from outside the room it can be withdrawn by turning a knob or handle (not shown) linked to the bolt through a squaresectioned spindle 3 and a thrower arm 4 keyed to the spindle. Normally, however, the arm 4 is held fast to a fixed plate 5 inside the lock by a series of, say, eight split plungers 6 arranged in a parallel sequence transversely of the lock, thereby to prevent withdrawal of the bolt 2 from the outside.

Each plunger is in two sections 6A, 6B and only when the split between each respective pair of plunger sections is aligned with the separation plane 7 between the arm 4 and plate 5 can the arm be rotated to withdraw the bolt 2.

The position of each plunger 6 relative to the arm 4 and plate 5 at any time is determined by a respective lever 8, against which the plunger is urged by a compression spring 9. The levers 8 are suspended on respective cross-pins 10 extending into slots 11 in the adjacent lock structure and normally each lever is urged under the combined action of two tension springs 1 2 and 1 3 into a "lock" position in which an upper bearing surface 14 of the lever engages a respective upper cam 15, and so that the respective plunger section 6B extends across the separation plane between the arm 4 and plate 5, thereby preventing rotation of the arm.Each cam 1 5 has a series of, say, seven sectors 1 5A of different radii and, as will be appreciated, the exact positioning of the corresponding lever 8, and therefore of the plunger 6, will depend upon which of the cam sectors the lever engages. Nevertheless, whichever sector is engaged, in the "lock" position the corresponding plunger section 6B to a greater or lesser degree extends through both the arm 4 and the plate 5.

In order to unlock the door from the outside a key card 16 of the form shown in Figure 3 is provided. This is inserted into an entry slot 1 7 in the lock casing to a depth determined by a springloaded catch 1 8 which engages a cut-out 1 6A in the card to retain the card against subsequent withdrawal until the door has been opened. The leading edge of the card is formed with a series of parallel notches 1 6B, one for each lever 8. When the base of the respective notch engages the lever as the card is pushed in, the lever is pivoted by the card in an anti-clockwise sense (as viewed in Figure 1) about the pivot point of surface 14 on the respective cam 1 5.If the depth of each notch is correctly related to the radius of the corresponding cam sector 1 5A each lever 8 will be pivoted just to the extent necessary to allow the corresponding plunger 6 to move into the position illustrated in Figure 1 in which the split between its two sections aligns with the separation plane between the arm 4 and plate 5, and the door can be opened. The arm 4 is linked to the catch 1 8 by means not shown, so that when the arm is depressed to open the door the catch automatically releases the card 1 6.

It will be appreciated that the required depth of each notch 1 6B in the key card is related to the rotational setting of the cam 1 5 associated with the respective lever 8. Resetting the cams 15, therefore, reprogrammes the lock by changing the positions of the lever pivot points and requires a key card with differently coded notches to unlock it. In the hotel context, the cams 1 5 would be reset for each new guest so that any keys retained by or stolen from previous guests will be ineffective to open the corresponding door. The keys themselves may be clipped or punched from plastics cards of a size and material similar to conventional credit cards.

A preferred form of mechanism whereby the lock combination can be reprogrammed automatically in conjunction with a key card is shown more particularly in Figure 4. An indexing member 1 9 is provided at a position laterally offset from the levers 8 (as seen also in Figure 2) and has a clevis 1 9A at its upper end which can engage one (at a time) of seven lateral pegs 1 SC spaced circumferentially around the adjacent flank of the end cam 15. Also, as shown in Figure 3, the key cards 1 6 have an additional notch 1 6C parallel to but offset from the notched 1 6B, and initially this additional notch is closed at the leading edge of the card by a thin bridge 1 6D.

Let it be supposed that the lock is installed in the door of an hotel room and a new key card 1 6 has been issued to a new guest for that room. At this stage the lock remains programmed for the key card issued to the previous guest but will be reprogrammed upon the first insertion of the new key card, as follows.

As the new card 16 is pushed in through the entry slot 1 7 the bridge 1 6D engages a bell crank lever 20 linked to the indexing member 19, to rotate the lever 20 and thereby lift the member 1 9. At this time the clevis 1 9A of the latter is in engagement with a peg 1 5C under the bias of a tension spring 21, so that as the member 1 9 is lifted the end cam 1 5 is rotated through an angle to bring the next one of its sectors 1 SA into alignment with the bearing surface 14 of the corresponding lever 8.A gear train 22 interconnects the cams 1 5 so that this rotation of the end cam also moves the other cams through specific angles, determined by the characteristics of the gear train, to present new sectors 1 5A to the corresponding levers 8. The relationship of the depths of the notches 1 6B of the new key card to those of the previous key card is so chosen, bearing in mind the characteristics of the gear train 22, that on completion of the cam rotation the cams will be in such position that the newdepth key card notches set the levers 8 into positions in which the plungers 6 permit rotation of the arm 4, and the door can therefore be opened.As the arm 4 is rotated it operates a drive lever 23 which in turn presses a punch 24 down onto the bridge 1 6D, cropping off that bridge to leave the notch 1 6C open-ended so that on subsequent insertions of the same key card the indexing member 19 is not operated and the lock combination remains unaltered. Also, as the bolt 2 is withdrawn a cam surface 2A on the bolt engages a finger 1 9B on the top of the indexing member 1 9 to withdraw the clevis 1 9A from the peg 1 SC and allow the member 19 to drop down to its lower position and engage with the next peg 1 so, without rotating the end cam in the reverse sense. Similar reprogramming will take place for each new, differently-coded key card issued to successive guests for the same room, it being understood that each new key code must bear a specified relationship to its predecessor to correspond with the lock code changes effected by the gear train 22. If an incorrectly coded key with a bridge portion 1 6D is used no net reprogramming will take place. Inserting the incorrect key may lift the indexing member 1 9 but since the bolt 2 cannot be withdrawn the clevis 1 9A will not be withdrawn from the peg 1 so; the member 19 will therefore return the end cam 1 5 to its previous position when it drops down upon removal of the incorrect key.

In point of fact it need not be arranged that all eight of the cams 1 5 are repositioned in this way by the "guest" keys. The use of, say, only three cams to provide "differs" for the same room may suffice, with the settings of the other cams being selected and fixed according to some convenient administrative scheme. For example, again in the hotel context, two cams may be set to the same selected positions throughout the guest rooms of a hotel with the depths of the two corresponding key notches being fixed likewise, of course, so that those two notches identify uniquely a particular establishment in a hotel chain. Similarly, a further cam may be set according to the floor on which a room is located, and the setting of two more chosen to identify the specific room number on that floor.

The gear train 22 can itself take several forms, e.g. a conventional "tripometer" type in which each succeeding member of the cam group is indexed one position for each complete revolution of the preceding cam, or some form of direct gearing such that the first (end) cam is indexed by one position, the second cam by two positions and the third by three positions and so on, for each new "guest" key, an advantage of the iatter being that more than one key notch 16B will always change between consecutive combinations.

Referring back to Figure 1, the illustrated lock further provides a facility for unlocking by a separately coded "master" key which is unaffected by changes in the combination for "guest" keys, and which can itself be reprogrammed without affecting the "guest" combination. To this end a further set of cams 25 is provided, and the corresponding levers 8 have a second bearing surfaces 26 for cooperation therewith. In operation of the lock by the "guest" key cards the surfaces 26 do not at any time come into contact with the cams 25.However, the effective length of a "master" key card between its catch aperture 1 SA and the bases of its leading edge notches (indicated at 1 6E in Figure 3) is greater than for "guest" key cards so that on insertion of a "master" card in the entry slot 1 7 the levers 8 are initially pivoted on the upper cams 15 as before, but are moved further than by a "guest" card, past the position in which the split between the respective plunger sections 6A and 6B aligns with the separation plane 7 between the arm 4 and plate 5, so that the plunger section 6A extends through both the arm and plate.As the lower portion of the lever is moved in by the "master card" still further, however, pivoting of the lever is transferred from the cam 15 to the cam 25 so that the upper portion of the lever leaves the cam 1 5 and begins to move the plunger 6 in the reverse direction. If the card is correctly coded, the plungers 6 will all be moved back by the extent required to re-align the split between the sections 6A and 6B with the separation plane 7 and the door can be unlocked. As will be appreciated, the final positions of the plungers are dependent only upon the relationship between the cams 25 and the corresponding notches of the "master" key card.

The master combination can be reprogrammed by resetting the cams 25, for which purpose a second reprogramming mechanism similar to that described for the "guest" combination may be employed.

It is also possible when (as described above) not all of the guest cams are indexed upon insertion of a new key and the non-indexed cams identify, say, hotel, floor and room, to provide a hybrid key operating on some "master" cams and some "guest" cams, thus acting as a "submaster" key allowing access to hotel, floor or room levels as appropriate.

Claims (7)

1. A mechanically reprogrammable lock comprising a set of pivotal levers to control locking and unlocking, the levers being biased normally into a locking condition but being pivotable into an unlocking condition by means of a correctly coded key; and wherein the levers are pivotable upon respective cams which are selectively adjustable in their rotational positions thereby to change the positions of the pivot points for the respective levers so that a correspondingly newly coded key is required in order to pivot the levers to the unlocking condition.

2. A lock according to claim 1 comprising a mechanism arranged to adjust the rotational positions of one or more said cams in a predetermined manner thereby to reprogramme the lock, upon the first operation of the lock by a newly coded key, whereby the newly coded key can unlock the lock if it bears a corresponding predetermined relationship to the coding of the previous key.

3. A lock according to claim 2 wherein said mechanism is operable by a specified portion of a newly coded key and the lock further comprises a mechanism adapted to modify that portion of the key upon the first unlocking of the lock by that key, so that further operations of the lock by the same key do not cause further movement of the cams.

4. A lock according to any preceding claim in combination with a key therefor in the form of a card; the lock including a slot for insertion of the card and the card having a profiled leading edge respective portions of which are arranged to engage respective levers to pivot the same by the amounts necessary to establish said unlocking condition.

5. A combination according to claim 4 when appended to claim 3 wherein the aforesaid portion of the card is a portion of the leading edge thereof and the lock comprises a mechanism adapted to crop that portion from the card upon the first unlocking of the lock thereby.

6. A lock or combination according to any preceding claim arranged to be unlocked also by a second correctly coded key; wherein the lock comprises second such cams for respective levers and such levers are pivotable on the respective first-mentioned cams, by the second correctly coded key but not by the first such key, to positions in which they engage the respective second cams and pivot thereon, thereby disengaging from the first-mentioned cams, to a condition equivalent to the aforesaid unlocking condition.

7. A mechanically reprogrammable lock substantially as hereinbefore described with reference to the accompanying drawings.