GB2309732A - An improved combination lock - Google Patents

Abstract

A combination lock for a secure environment, comprising a mechanical bolt-release mechanism (11) adapted to be located on one side of a closure member (40), within the secure environment (43), code verification means (101) associated with the bolt-release mechanism (11) such that bolt release can be effected only upon verification of entry of a correct code, and means (49) for applying input signals to the code verification means (101) from user interface means (47) located on the other side of the closure member (40) from the said one side thereof, in which the input signals from the user interface means (47) are transmitted through the closure member (40) within a mechanical lock-release member (55).

Description

AN IMPROVED COMBINATION LOCK The present invention relates generally to an improved combination lock.

Combination locks are used to control access to a closed or secure environment, such as the interior of a safe or a strong room, and have the advantage over a key-operated lock that the user does not require to carry with him any key or keys to operate the lock, but merely needs to know the authorisation code which can be entered into the lock in order to cause it to release. The majority of known combination locks are operated by a rotary dial and the authorisation code is stored mechanically as a series of tumblers and/or fences which define a mechanical configuration accessed by turning the dial clockwise and anticlockwise to and fro between different selected positions.

Entirely mechanical locks have a number of advantages including the fact that they need no separate power supply for energisation, but suffer from the disadvantage that the mechanical interconnections can be sensed so that a skilled operator can release the lock without previously knowing the combination simply by detecting the sound emitted by the mechanism or the feel of the lock dial as it reaches a position in which the cooperating components (fences or gates or the like) are in alignment. In order to overcome this disadvantage it has been proposed to provide an electronic dial combination lock which uses a dial having divisions to enter a combination code in the connectional way to gain entrance to the secured environment.

One known such lock has a spindle journalled within the lock for both rotational and axial movement to cause a push pin located on an internal cam wheel to engage one of a plurality of pressure-sensitive switches within the lock located in an evenly-spaced circular pattern centred on the shaft's axis, each switch being capable of making a discrete, unique electrical connection. A circuit within the secure environment senses the electrical connections and detects when a given subset of connections has been made corresponding to the lock's authorisation code, and this circuit then initiates the generation of an electrical signal within the secure environment. Arrival of the signal at the operating member of a lock-release mechanism (for example a solenoid) permits a conventional fence lever to engage a cam wheel so that a bolt within the lock may be withdrawn. An electronic combination lock has the advantage that it does not allow an unauthorised user to obtain information about the lock release code from the characteristics of the tumblers or fences as in a mechanical system by manipulation of the combination dial, and should in theory be more secure. It is, however, necessary to provide a power supply for an electronic lock and this constitutes a disadvantage if the power required to operate the lock is significant since it implies the need for mains power rather than battery power.

Locks in which the force required to move the bolt between its released and locked position is applied manually, whilst the interconnection between the boltoperating manual lever or knob and the bolt itself is controlled by electrical means such as a solenoid are also known. One such system utilises a lever pivotally connected to the bolt and engageable in a'cam wheel upon energisation of a solenoid so that turning the lock spindle by means of a knob or handle can cause release of the lock, whereas if the solenoid is de-energised the link is not engaged and is held out of engagement with the cam so that turning the spindle, and therefore the cam, has no effect on the bolt.

In such a lock correct input by the user of a release code is used by the lock simply to enable operation of a bolt-release mechanism although, of course, mechanical or electrical operation of the bolt-release mechanism may also be effected.

The present invention seeks to provide a combination lock with additional security in which the disadvantages of known such locks are at least largely overcome.

According to the present invention, therefore, there is provided a combination lock for a secure environment, comprising a mechanical bolt-release mechanism adapted to be located on one side of a closure member, within the secure environment, code verification means associated with the bolt-release mechanism such that bolt release can be effected only upon verification of entry of a correct code, and means for applying input signals to the code verification means from user interface means located on the other side of the closure member from the said one side thereof, said code verification means acting to compare input signals with a previously-stored authorisation code and operable to issue an authorisation signal only when the input signal matches the said authorisation code, in which the input signals from the user interface means are transmitted through the closure member within a mechanical lock-release member.

In a preferred embodiment of the present invention the mechanical lock-release member is a spindle of the lock mechanism and this is turned by a manually operable member which forms part of a housing for the user interface means.

The user interface means preferably includes a key pad for entry of the code intended to match the authorisation code, the key pad being mounted on a part of the housing such as a front panel. The arrangement is such that when that part of the housing which forms the bolt-operating member is displaced in order to effect release of the bolt via the bolt-release mechanism the part or panel of the housing on which the key pad is mounted remains in the same orientation.

The said assembly including the manually-operable boltrelease member may be housed in a housing in which replaceable batteries for powering the electrical and/or electronic components of the combination lock are releasably housed on the side of the said closure member outside the secure environment. Exchange of the batteries can be effected, therefore, quickly and easily without compromising the security of the lock.

Obviously, the lock cannot be released without the batteries so that unauthorised battery removal will, likewise, not compromise its security.

The housing for the said assembly may include a fixed part secured in use to the closure member and a relatively turnable or rotatable part constituting the said manually-operable bolt-release member, the said fixed part having mounting means on which the electronic circuit of the user interface is mounted. The electronic circuit of the user interface may, for example, be secured to the panel on which the key pad is mounted.

In the preferred embodiment of the present invention the said mounting means comprise one or more projecting studs on which a printed circuit board forming at least part of the electronic circuit of the user interface is mounted.

A combination lock formed as an embodiment of the present invention may be so structured that the turning movement of the said manually-operable bolt-release member is limited by contact of a part thereof against one or other of the said projecting studs.

One of the particular advantages of the present invention is that it may be used in place of a conventional rotary dial combination lock, either as original equipment or as a subsequently fitted replacement. For this purpose the housing component of which the said manually-operable bolt-release member forms part may comprise an annular body with a cylindrical wall forming a finger grip by which the member is turnable to effect release of the lock bolt when a correct authorisation code has been entered. The key pad may then be provided as a suitable input system located at a central point of a rotary dial.

In this case the peripheral rim of the rotary dial is not turnable to effect the authorisation code selection, but only to operate the bolt-release mechanism when a correct authorisation code has been entered by acting on the key pad. If the correct code has not been entered turning of the peripheral rim of the rotary dial has no effect.

An electrical connection from the user interface to the authorisation signal generator of the bolt-release mechanism passes through the closure member within, for example, a spindle of the manually-operable boltoperating member.

In the preferred embodiment discussed above, the studs may have shoulders or flanges against which engages a lip or flange of the said manually-operable bolt-release member whereby to retain it in position rotatably with respect to the fixed body of the housing.

Such studs may, further, have shoulders defining an engagement surface for a face plate or planar cover member constituting the panel or part bearing, or through which are exposed, means for entering the said authorisation code such as the key pad.

The manually-operable bolt-release member preferably has a lip or flange against which the periphery of the said face plate or planer cover engages for support against externally applied pressure.

One embodiment of the present invention will now be more particularly described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a generally perspective view of a door fitted with a rotary combination lock formed as an embodiment of the present invention; Figure 2 is a face view of the rotary dial housing with the front panel removed; Figure 3 is a sectional view taken on the line III III of Figure 2; Figure 4 is a sectional view taken on the line IV-IV of Figure 2; Figure 5 is a perspective view of the rotary dial housing with the front panel and circuit components removed; Figure 6 is a view from the interior of the lock mechanism forming part of the electronic rotary combination lock of the present invention; and Figure 7 is a view similar to that of Figure 6 showing the components in a different working configuration.

Referring now to the drawings, a door generally indicated 40, and which may for example be the door of a safe or other portable container 43 is shown with a rotary dial combination lock 39 formed as an embodiment of the present invention.

As can be seen in Figure 1 the lock has a lock body 11 from which a bolt 19 can be caused to project or retract by turning a lock-operating member 46 which, in this embodiment, is manually-operable and formed as the cylindrical wall of the rotary combination dial housing.

A front panel 47 of the rotary dial combination lock bears a screen 48 and a key pad 49 by which an authorisation code may be entered into the combination lock. Unless the correct authorisation code is entered the lock-operating member 46 is disengaged from the mechanism within the lock 11 such that rotation thereof has no influence on the position of the bolt 19. Once a correct authorisation code has been entered on the key pad 49 the lock acts to generate an authorisation signal which activates the mechanism to interconnect the lockoperating member 46 and the mechanism (to be described) by which the bolt 19 is displaced such that subsequent rotation of the lock-operating member 46 causes the bolt 19 to extend or retract as appropriate. The combination lock 39 may have a timing mechanism (not shown in Figure 1) by which the interconnection between the lockoperating member 46 and the bolt-displacement mechanism for the bolt 19 is maintained interconnected for a fixed time period, or there may be a motion sensor operable to disconnect the mechanism once a bolt-displacement movement has taken place.

The interior structure of the rotary dial combination lock housing 39 is illustrated in more detail in Figures 2 and 3. The housing 39 comprises a fixed dial body 51 which can be secured in place, for example by means of bolts or screws passing through openings 52, 53.

The body 51 is generally circular having a cylindrical side wall 54 and a central opening 55 through which passes a hollow spindle 56 of a manually-operable lock operating member generally indicated 46 in the form of a shallow cup-shape body having a cylindrical side wall 58 and a bottom wall 59 from which the spindle 56 projects.

The bottom wall 59 also has two large generally segmental apertures 60, 61 defined along the arcuate perimetral rim by an inwardly directed radial flange 62, 63 forming a lip which is engaged by the radial flanges 64, 65 of respective retainer pins 66, 67 which have a central shouldered portion 68, 69 and a narrower spigot portion 70, 71 located in respective housing apertures 62, 63 within which they are retained by suitable fixing means such as screws, rivets or by upsetting the peripheral end into a suitable counter-bored or bevelled end portion of the spigot housing apertures 72, 73 respectively in order securely to fix the narrow spigot portions 70, 71 of the retainer pins 66, 67 securely in place in the fixed dial body 51.

The central shouldered portions 68, 69 of the retainer pins 66, 67 have an axial length slightly greater than the thickness of the inwardly directed flange or lip 62, 63 of the bottom wall 69 of the operating member 70 so as to retain this operating member in position against separation from the fixed dial body whilst allowing free turning movement of the operating member about the spindle 56 when gripped by a user's fingers at the cylindrical side wall 58. Turning movement of the operating member 46 is limited by the circumferential dimension of the segmental apertures 60, 61 to be approximately 450 in either directional sense from the central position illustrated in Figure 2.

The retainer pins 66, 67 also include a column portion 74, 75 on the side of the flange 64, 65 opposite the spigot portions 70, 71, having a terminal locator portion 76, 77 of reduced diameter defining, with the end of the column portions 74, 75 respective shoulders 78, 79. The shoulders 78, 79 serve to define a plane for locating the position of a front panel 47 which is fitted on the locator portions 76, 77 of the columns 74, 75 and retained in position by any suitable means such as threaded set screws (not shown) threadedly engaged in the interior of the hollow columns 74, 75.

The front panel 47 carries the screen 48 and key pad 49, and its rear face carries a printed circuit board 80 linked by connections 81 to the screen 48 and connections 82 to the key pad 49. The connections 81, 82 are shown schematically and are intended to represent both mechanical support of the printed circuit board 80 and electrical connection of the components thereon to the screen 48 and key pad 49 respectively. The printed circuit board 80 carries an electronic circuit, schematically illustrated in Figure 3 which converts the key strokes entered by a user on the key pad 49 onto electrical signals, and transmits them on a signal line 83 to a verification circuit 101 for generating an authorisation signal, when a correctly-entered code is recognised, for transmission on output lines 102 to a solenoid 100 of the lock-release mechanism. The code storage and comparison circuits 101 will be described in more detail below.

Power for the circuit carried on the printed circuit board 80 is taken from two batteries 84, 85 carried, as can be seen in Figure 4, on a battery carrier 86 having two arms 87, 88 with appropriately shaped battery retainer clips 89, 90. The battery carrier arms 87, 88 extend from a battery carrier body 91 having an arcuately curved outer surface 92 the curvature of which matches that of the fixed dial body 51 and which has two finger grip recesses 93, 94 by which the battery carrier body 91 may be gripped by a user for insertion into or withdrawal from the rotary dial body 51. The rotary dial body 51 has two elongate sockets 95, 96 for receiving the battery carrier arms 87, 88, and the elongate battery-receiver sockets 95, 96 have respective contacts 97, 98 connected to power leads 99 (see Figure 3) leading to the circuit carried on the printed circuit board 80. The electrical battery contacts 97, 98 are shaped to engage the contact terminals of the batteries 84, 85 carried by the battery carrier arms 87, 88 as the battery carrier body 91 is introduced fully into the rotary dial body 51.

In use of the electronic rotary combination lock of the present invention, therefore, an appropriate code is entered in the key pad 49 by the user. The code entered is displayed on the screen 48 and signals representing the key strokes are transmitted to the verification circuit 101 along lines 83. If the correct code is received an authorisation signal is generated by the verification circuit 101 and this signal is transmitted to the solenoid 100 of the lock-release mechanism on the lines 102. This, as will be described in more detail below, enables the connection between the spindle 56 and the bolt-displacement mechanism of the lock 11 to be completed so that the user may withdraw the bolt by turning the bolt-operating member 58 in the manner of a conventional door knob.

One embodiment of the bolt-release mechanism by which the bolt 19 is extended or withdrawn is illustrated in Figures 6 and 7.

The general operating principle of the lock is as follows: the spindle 56 is maintained uncoupled from the bolt 19 unless the specific enablement or authorisation signal is received ratifying the authenticity of the user.

As can be seen in Figure 6, the lock comprises a body generally indicated 11, conveniently of metal (although other materials of sufficient strength may also be used) having a rectangular form with two parallel elongate ridges 12, 13 defining between them a central, longitudinally extending channel 15 within which the moving components of the lock are housed. A cover (not shown) fits over the body 11, resting on the crests of the ridges 12, 13, to retain the components in place.

Four through-holes 14 are provided for securing the body 11 to the closure member or door 40 which is to be locked. The fixings, for example bolts, which pass through the holes 14 may also serve to retain the cover (not shown) in place or the cover may be secured in place by different means (not shown).

Within the elongate channel 15 which extends for the whole length of the body 11 is formed a further, deeper slot 16 within which the bolt 19 slides. Slot 16 has an end wall 18 defining the leftward end of travel (as viewed in Figure 6) of the bolt 19.

Projecting laterally from the bolt 19 is a bolt pin 20.

A bolt locking lever 21, having a generally U-shape lateral notch 22 adjacent its free end, is pivotally connected to the body 11 at a pivot 23 in line with the operating pin 20 in the direction of travel of the bolt 19 so that, when the U-shape notch 22 is engaged over the operating pin 20, the bolt 19 is retained by the lever 21 against movement in either direction along the slot 16.

A torsion spring (not shown) acts on the lever 21 resiliently biasing it in an anticlockwise sense as viewed in Figure 6 so that it is continually urged towards engagement with the operating pin 20. The lever 21 has an inner limb portion 24 and an outer limb portion 25 joined by an elbow 26. Beyond the U-shaped notch 22 the outer limb portion 25 has a nose portion 27 the function of which will be described in more detail below.

The hollow spindle 56 is connected by a shaft 29 to a spur gear or pinion 28 pivoted about an axis 29 of the spindle and located in the channel 15 and approximately in line with the bolt pin 20 and the locking lever pivot 23.

The pinion 28 meshes with a rack 129 which forms part of a bolt-operating link generally indicated 30. The boltoperating link 30 comprises a body portion 31 from which the rack 129 extends. The rack 129 is formed on an elongate link arm having a plurality of teeth 32 projecting from one side of the link arm, the other side of the link arm being defined by a flat face 33.

Adjacent the point where the flat face 33 of the link arm meets the body 31 of the link 30 a trapezoidal cam 34 projects from the body 31.

The body 31 is defined, opposite the trapezoidal cam 34 by a face 35 parallel to the face 33 and an inclined face 36 joining the parallel face 35 to the rack 129. The body 31 of the lever 30 has a nose portion 37 in which is formed an arcuately curved hook recess 38 the curvature of which matches exactly that of the bolt pin 20 and which extends substantially in a semicircle, merging at one end into the face 35 which is tangential to it.

The rack 129 is held in engagement with the pinion 28 by a rack guide member 140 which has a cylindrical surface 141 and an axis parallel to the axis of rotation 29 of the pinion 28 which defines, with the circumscribing circle of the pinion 28, a passage for the rack 129 which can only enter the passage if the teeth 32 of the rack 129 are in mesh with the teeth of the pinion 28. The cylindrical surface 141 of the rack guide 140 allows the orientation of the rack to vary, however, as will be described in more detail below. Rotation of the pinion 28 in an anticlockwise sense from the position viewed in Figure 6 will therefore cause the rack 129 to translate from right to left within the channel 15.

Adjacent the ridge 13 of the body 11, within the channel 15 and to the right of the rack guide 140, is a small circular hole 41 parallel to the axis 29 of the pinion 28.

Within the hole 41 is guided a solenoid pin 42 operated by a solenoid 100 (see Figure 3).

When the solenoid 100 is energised by the authorisation signal generated upon entry of the correct authorisation code at the key pad 49 the pin 42 is caused to project from the hole 41 so that its tip lies in the channel 15 between the trapezoidal cam 34 and the cylindrical cam guide surface 141. If the pinion 28 is then rotated anticlockwise when the solenoid is energised and the pin 42 is projecting into the channel 15, the trapezoidal cam 34 rides over the pin 42 as the link 30 is displaced towards the left by the action of the pinion 28 on the rack 129. This displaces the body 31 and nose portion 37 of the link 30 causing the nose portion 37 to come into contact with the nose 27 of the bolt locking lever 21 so as to disengage this from the bolt pin 20 and, instead, engage the semi-cylindrical hook recess 38 of the nose portion 37 of the link 30 with the bolt pin 20. The relative positions of the components is such that the semi-cylindrical hook recess 38 engages the bolt pin 20 over the entire half of its cylindrical surface on the opposite side of the bolt pin 20 from the locking lever pivot 23 and the ends of which are defined by the diameter of the bolt pin 20 which extends perpendicular to an imaginary line joining the bolt pin 20, the locking lever pivot 23 and the axis 29 of the spur gear or pinion 28.

Continued rotation of the pinion 28 thus causes the bolt pin 20, and therefore the bolt 19, to be withdrawn into the lock body 11 and, even after the trapezoidal cam 34 has passed the solenoid pin 42, the bolt-operating lock 30 remains engaged on the bolt pin 20 as long as the rotation of the pinion 28 continues.

Figure 7 illustrates the position of the components when the pinion 28 has been rotated fully to withdraw the rack 129 to the left (as viewed in the drawing) carrying the bolt 19 to its fully-retracted position. As will be seen, the trapezoidal cam 34 has been moved to a position beyond the solenoid pin 42 allowing the solenoid pin 42 to be retracted if the solenoid is de-energised without any force being exerted on it by the components of the lock.

Reverse rotation of the pinion 28 will cause the boltoperating lever 30 to push the bolt 19 back to its original extended position by engagement of a thrust pin 50 (shown in broken outline in the drawings) which projects from the opposite face of the bolt-operating lever 30 from that which is seen in the drawings, and which engages a rear face 44 of the bolt 19 providing the pin 42 is at this time again or still projecting from the hole 41 thereby ensuring that the lever 30 is laterally displaced to a position where the thrust pin 50 is in register with the rear face 44.

If, on the other hand, the pin 42 is retracted into the hole 41, reverse rotation of the pinion 28 simply allows the semi-circular hook recess 38 to disengage from the bolt pin 20 whereupon the lever 30 is spring biased to a position where the trapezoidal cam 34 contacts the ridge 13, this motion being allowed by the loose interengagement of the link 30 between the cylindrical rack guide 40 and the teeth of the pinion 28. In this condition rotation of the pinion 28 causes displacement of the link 30 but no displacement of the bolt 19 because the end face 44 of the bolt has an inclined portion 44a, as seen in Figure 6 which defines a void space into which the thrust pin 50 can move without displacing the bolt 19.

If the pinion 28 is rotated anticlockwise whilst the bolt 19 is extended, but without energisation of the solenoid to cause the solenoid pin 42 to project from the hole 41, the link 30 is drawn by the rack 129 towards the left with the trapezoidal cam 34 sliding along the side wall of the ridge 13 without any displacement of the nose portion 37 into engagement with the bolt pin 20.

Unless the solenoid is energised, therefore, by correct entry of the authorisation code rotation of the lock spindle (and thus the pinion 28) will cause neither retraction of the bolt 19 when it is extended nor extension of the bolt 19 when it is retracted. Moreover, in its extended position, the bolt 19 is securely held extended by the bolt-locking lever 21. The bolt 19 cannot therefore, be forced back to obtain release of the door 40 secured by the lock. Obviously, for highsecurity applications the bolt 19 will be made of a material highly resistant to cutting. Turning the dial rim 58, constituted by the cylindrical side wall of the lock operating member 46, has no effect whatsoever unless the correct code is entered, and this can turn through 90E (ie 45E to either side of the central position) freely, being uncoupled from the bolt.

The circuit diagrams of Figures 8 and 9 respectively illustrate the main circuit components of the two separate circuits of the electronic combination lock of the invention. As described in relation to Figure 3 the circuit shown in Figure 8, on the printed circuit board 80 sends electrical signals resulting from key strokes on the keyboard 49 on lines 83 to the circuit on printed circuit board 101 shown in Figure 9, which stores the authorisation code, compares it with signals arriving from printed circuit board 80 and, if the signals coincide, generates an authorisation signal which is sent to the solenoid 100.

The circuit 80 of Figure 8 has a central processor 105 to which the key pad 49 is connected by lines 106. Biasing resistors 107-111 are connected between respective lines 106 and ground. Power to the processor 105 is supplied via lines 99+ and 99 from battery terminals 112 and 113.

Battery line 99+ leads to a transistor 114 forming part of a "wake up circuit comprising a resistor 115 across the base-emitter junction of transistor 114, a resistor 116 connecting the base of transistor 114 to the collector of a transistor 117, and a resistor 118 connecting the base of transistor 114 to the collector of a transistor 119.

This circuitry allows a minimum power consumption to be achieved by enabling the processor to adopt a quesicent state until a key of the key pad 49 is depressed and then to become active with the battery power applied to the line Vcc.

Bidirectional communication between the processor 105 and the lock circuit 101 takes place on a single signal line 83s which connects the terminal 120s of Figure 8 with the terminal 126s of Figure 9. The circuit 101 also receives battery power on lines 83+ and 83- which connect terminals 120t and 12G of the circuit 80 shown in Figure 8 with terminals 126+, 126 of the lock circuit 101 shown in Figure 9. Thus the lines 83 comprise only three lines passing through the hollow spindle 56 shown in Figure 3 so that the restricted dimensions of the passage through the spindle do not constitute a physical limitation and it is not necessary to pierce the closure member 40 with a separate hole to carry the communicating wires.

The externals circuit 80 includes the LCD display 48 connected to an LCD driver 121 fed from the processor 105 via lines 122, 123, and two pairs of light-emitting diodes, 160, 161 and 162, 163 fed from the central processor 105 via respective resistors 164, 165. These light-emitting diodes light up in selected combinations to indicate to the user the current status of the lock.

The "internal" lock circuit 101 comprises a processor 124.

Signal line 125s and power lines 125+ and 125- connected to respective terminals 126s, 126+ and 126- to which lines 83s, 83+ and 83- lead respectively, carry signals to and from processor 124 and supply it with power in an input filter comprising resistor 127 and capacitor 128, protection diode 129. A latching circuit 130 holds the processor on when powered up.

The authorisation code is stored in a memory 131, in this embodiment an Electrically Alterable Read Only Memory (EAROM) connected to the processor 124 by lines 132, 133 and between battery voltage and ground by lines 134, 135 respectively. Two operational amplifiers 136, 137 form the basis of a battery condition sensing circuit including resistors 140, 141, 142, Zener diode 143 and resistors 144, 145 the output signals from which are a 80 as a master and the processor 124 of circuit 101 as a slave. By utilising bidirectional communication on line 83s the two circuits can maintain a cycle of phases in synchronisation with one another and thereby operate to establish the input of the correct code utilising highly secure protocols. When a correct code is entered the processor 124, having compared the input signal arriving at terminal 126s with the stored code and established a match, emits an authorisation signal on output line 150 which is led via resistor 151 to the base of a power transistor 152 in series with the solenoid 100 between the power supply line 125+ and ground, with a protection fuse 153 and a polarity reversal protection diode 154.

The protocols for communication between the processor 105 and 124 allows the authorisation signal to be generated for a predetermined time to set a time "window" during which the lock may be opened. This is signalised to the user by illuminations of one of the light-emitting diodes 160, 161; 162, 163 on the front panel of the rotary dial.

The protocols may also allow for a limit on the number of incorrect attempts, imposing a long time delay (eg 15 to 30 minutes) before further attempts will be accepted; again this can be signalled to the user via the lightemitting diodes 160-163. The storage of multiple authorisation codes is also possible so that different users can have different numbers to use, and the lock may be programmed to accept different numbers at different times of day thereby allowing for programmed patterns of use by a plurality of users.

The electronic rotary dial combination lock of the present invention thus provides a highly secure lock the shape and dimensions of which are suitable to allow it to be retro fitted in place of known mechanical rotary dial combination locks, and which is simple and clear to operate. Because the front panel 47 is carried on the columns 74, 75 which in turn are secured to the dial body 51, rotation of the dial rim 46 to withdraw the bolt 19 does not cause corresponding rotation of the front panel and consequently the screen 48 and key pad 49 remain upright at all times. Because of the bidirectional communication through signal line 835 the wires can be passed through the hollow spindle 56 (which would not be possible if there were a large number of communication wires) and this means that retro fitting in place of a mechanical lock can take place without the need for drilling any extra holes through the safe door to allow passage of the wires.

Claims (15)

1. A combination lock for a secure environment, comprising a mechanical bolt-release mechanism adapted to be located on one side of a closure member, within the secure environment, code verification means associated with the bolt-release mechanism such that bolt release can be effected only upon verification of entry of a correct code, and means for applying input signals to the code verification means from user interface means located on the other side of the closure member from the said one side thereof, said code verification means acting to compare input signals with a previously-stored authorisation code and operable to issue an authorisation signal only when the input signal matches the said authorisation code, in which the input signals from the user interface means are transmitted through the closure member within a mechanical lock-release member.

2. A combination lock as claimed in Claim 20, in which the said mechanical lock release member is connected to a manually-operable bolt-release member which forms part of a housing for the user interface means.

3. A combination lock as claimed in Claim 2, including a key pad mounted on a part of the said housing which remains in the same orientation when the part of the housing constituting the bolt-release member is turned to displace the bolt.

4. A combination lock as claimed in any preceding claim, in which the said assembly including the manuallyoperable bolt-release member is housed in a housing in which replaceable batteries for powering the electrical and/or electronic components of the combination lock are releasably housed on the side of the said closure member outside the secure environment.

5. A combination lock as claimed in any of Claims 2, 3 or 4, in which the housing for the said assembly includes a fixed part secured in use to the closure member, and a relatively turnable or rotatable part constituting the said manually-operable bolt-release member, the said fixed part having mounting means on which the electronic circuit of the authorisation code generator is mounted.

6. A combination lock as claimed in Claim 5, in which the said mounting means comprise projecting studs carrying a printed circuit board forming at least part of the said user interface means.

7. A combination lock as claimed in Claim 6, in which the turning movement of the said manually-operable boltrelease member is limited by contact of a part thereof against one or other of the two said projecting studs.

8. A combination lock as claimed in any preceding claim, in which the said manually-operable bolt-release member has an annular body with a cylindrical wall forming a finger grip by which the member is turnable to effect release of the lock bolt when a correct authorisation code has been entered.

9. A combination lock as claimed in any of Claims 6 to 8, in which the said studs have shoulders or flanges against which engages a lip or flange of the said manually-operable bolt-release operating member whereby to retain it in position rotatably with respect to the fixed body of the housing.

10. A combination lock as claimed in any of Claims 6 to 9, in which the said studs have shoulders defining an engagement surface for a planar cover member of the housing.

11. A combination lock as claimed in Claim 10, in which the said manually-operable bolt-release member has a lip against which the periphery of the said planar cover engages for support against externally applied pressure.

12. A combination lock as claimed in any preceding claim, in which the said authorisation signal is emitted for a predetermined time period to define a time window within which the lock is operable.

13. A combination lock as claimed in any preceding claim, in which the said user interface means includes visual display means operable to display lock status information to a user.

14. A combination lock substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.

Amendments to the claims have been filed as follows CLAIMS 1. A combination lock for a secure environment, comprising a mechanical bolt mechanism adapted to be located on one side of a closure member, within the secure environment, code verification means for verification of entry of a correct code by comparing input signals from a user interface such as a keypad with a previously-stored authorisation code and operating to issue an authorisation signal when the input signal matches the said authorisation code, in which the input signals from the user interface are transmitted through the closure member within a mechanical lock-operating member which is displaceable by a manually-operable bolt control member which forms part of a housing for the user interface means, the user interface being mounted on a part of the said housing which remains in the same orientation when that part of the housing constituting the said bolt control member is turned to displace the bolt.

2. A combination lock as claimed Claim 1 in which the said housing for the user interface also houses replaceable batteries for powering the electrical and/or electronic components of the combination lock.

3. A combination lock as claimed in Claim 1, or Claim 2, in which the said housing includes a fixed part secured in use to the closure member, and a relatively turnable part constituting the said manually-operable bolt control member.

4. A combination lock as claimed in Claim 3, in which the said fixed part has mounting means comprising projecting studs carrying a printed circuit forming at least part of the said user interface means.

5. A combination lock as claimed in Claim 4, in which the turning movement of the said manually-operable bolt control member is limited by contact of a part thereof against one or other of the two said projecting studs.

6. A combination lock as claimed in any preceding claim, in which the said manually-operable bolt control member has an annular body with a cylindrical wall forming the rim of the said housing, by which the member is turnable to effect displacement of the lock bolt when a correct authorisation code has been entered.

7. A combination lock as claimed in any of Claims 4 to 5, in which the said studs have shoulders or flanges against which engages a lip or flange of the said manually-operable bolt control member whereby to retain it in position rotatably with respect to the fixed part of the housing.

8. A combination lock as claimed in any of Claims 4 to 7, in which the said studs have shoulders defining an engagement surface for a planar cover member of the housing.

9. A combination lock as claimed in Claim 8, in which the said manually-operable bolt control member has a lip against which the periphery of the said planar cover engages for support against externally applied pressure.

10. A combination lock as claimed in any preceding claim, in which the said authorisation signal is emitted for a predetermined time period to define a time window during which the lock bolt is displaceable by turning the said bolt control member.

11. A combination lock as claimed in Claim 10, in which the mechanical bolt mechanism acts to uncouple the said lock-operating member from the bolt except during the said time window.

12. A combination lock as claimed in any preceding claim, in which the said user interface means includes visual display means operable to display lock status information to a user.

13. A combination lock as claimed in any of Claims 2 to 13, in which the said replaceable batteries are carried in a carrier removably located in the said part of the housing which remains in the same orientation when the bolt control member is turned.

14. A combination lock as claimed in Claim 13, in which the said part of the housing which remains in the same orientation when the bolt control member is turned comprises a fixed part of the housing, and the battery carrier has a surface at least part of which lies substantially flush with the outer surface of the fixed part of the housing when the battery carrier is fitted in position in the housing.

15. A combination lock substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.