ELECTRONICALLY OPERATED LOCK

The present invention relates to an electronic lock.

Figures 1 and 2 show a conventional cylinder lock 101 comprising an outer casing 103 having a cylindrical bore 105 therethrough. A plug 107 is housed in the cylindrical bore 105. In order to open the lock, the plug 107 must rotate in the cylindrical bore 105.

One end of the plug 107 comprises a shaped aperture known as the key slot 109. A suitably shaped key 111 fits in the key slot 109. The other end of the plug 107 has a lever (not shown) which activates a mechanism (not shown) to retract a locking bolt (not shown) from a recess in a door (not shown) . A series of bores 113a to 113e, typically five or six of them, are radially drilled into the plug 107. These bores 113a to 113e each contain pins called differ pins 115a to 115e, which are of various lengths, and which are rounded at one end to permit a key 111 to easily radially outwardly displace them when the key 111 is inserted into the key slot 109.

Radially outwardly of each differ pin 115a to 115e is a corresponding driver pin 117a to 117e (only one shown) , which is spring-loaded by means of a spring 118. The outer casing 103 also has several radial bores 119a to 119e (only one shown) , which communicate with the bores 113a to 113e of the plug 107 and which house the spring- loaded driver pins 117a to 117e.

With a properly shaped key 111 inserted into the key slot 109 of the plug 107, the pins 115a to 115e and 117a to 117e will move radially outwardly, and because the length

of the pins is specially designed to match the shape of the key 111, the junction between each differ pin 115a to 115e and each driver pin 117a to 117e will exactly align with shear line A. This alignment allows the key 111 and therefore the plug 107 with it, to rotate, thereby retracting the locking bolt (not shown) from the recess in the door (not shown) and opening the lock.

When the correct key 111 is not in the key slot 109, the pins 115a to 115e and 117a to 117e are pushed down into the plug 107 by the springs 118, and the driver pins 117a to 117e straddle the shear line A, thereby preventing the plug 107 from rotating, thereby keeping the lock closed.

Despite being a commonly used lock and key arrangement, the arrangement described above includes a number of disadvantages. For example, the key 111 may easily be lost, thereby presenting a potential security threat to the owner of the lock and key arrangement if the key is subsequently found by a person who would not normally be authorised to gain access to the premises. Moreover, if the key is lost, the owner of the key is inconvenienced by being unable to gain access to the premises.

Moreover, the lock described above may easily be manipulated (that is, "picked") to allow unauthorised rotation of the plug in the outer casing even without the correct key.

Preferred embodiments of the present invention seek to overcome or at least alleviate the above disadvantages of the prior art.

In accordance with a first aspect of the present invention, there is provided a lock comprising: -

(i) a support;

(ii) a first element adapted to be rotated relative to said support between a first position and a second position;

(iii) a second element mounted to said support and adapted to be moved between a third position, in which rotation of said first element relative to the support is transmitted to said second element to enable the lock to be changed from a locked to an unlocked condition thereof, and a fourth position, in which rotation of said first element relative to the support is not transmitted to said second element to maintain the lock in a locked condition thereof; and

(iv) electromagnetic means for moving said second element from said fourth position to said third position.

This provides the advantage that a user simply has to initiate the energising of the electromagnetic means to move the second element from the fourth position to the third position, and then rotate the first element, in order to open the lock. In this way, a user is not required to carry a key, which would be susceptible to becoming lost or stolen.

The first element may comprise a knob having a recess, and said second element may comprise a locking portion, wherein when said second element is in said respective

third position, said locking portion engages said recess, and when said second element is in said respective fourth position, said locking portion does not engage said recess .

This provides the advantage that when the electromagnetic means is energised, the locking element of the second element may easily locate in the shaped recess to allow rotation of the second element and hence opening of the lock, when the first element is rotated.

Said recess and said locking element may be non-circular in cross-section.

This provides the advantage that the second element will follow rotation of the first element as the first element is rotated, and not simply remain at rest with respect to said support as the first element is rotated.

A longitudinal axis of said recess and a longitudinal axis of said second element may be substantially parallel to each other.

This provides the advantage that the lock is "in-line," therefore enabling the lock to be fitted into body portions of existing cylinder-type locks, without significant modification of the body portion being required.

This provides the further advantage that the lock is compact .

The first element may comprise a knob connected to a drive assembly, and said drive assembly may comprise

means for automatically returning the knob to its first position .

This provides the advantage that the knob is not inadvertently left in its second condition, which would otherwise result in residual frictional forces preventing the second element from moving to its fourth position.

Said drive assembly may comprise an inner drive disposed within an outer drive .

This provides the advantage that the lock is compact.

Said outer drive may be connected to said knob, and said inner drive may be engageable with said second element.

Said inner drive may comprise at least one connecting element, and said second element may comprise a corresponding connecting element, wherein when said second element is in said respective third position, said connecting element engages said corresponding connecting element, and when said second element is in said respective fourth position, said connecting element does not engage said corresponding connecting element.

This provides the advantage that when the electromagnetic means is energised, the corresponding connecting element of the second element may easily engage said connecting element of said inner drive to allow rotation of the second element and hence opening of the lock, when the first element is rotated.

A longitudinal axis of said drive assembly and a longitudinal axis of said second element may be substantially parallel to each other.

This provides the advantage that the lock is "in-line," therefore enabling the lock to be fitted into body portions of existing cylinder-type locks, without significant modification of the body portion being required .

Said means for automatically returning the knob to its first position may comprise at least one compression spring disposed between said inner and outer drives, which is compressed as the knob is rotated from said first position to said second position, and which expands to rotate the knob back to said first position in the event that a user releases the knob.

This provides the advantage that the lock is compact and includes relatively few moving parts.

The lock has a maximum cross-sectional diameter of approximately half an inch.

This provides the advantage that the lock may be fitted into an existing mechanical lock cylinder having a diameter of approximately half an inch.

Said electromagnetic means may comprise a coil connectable to a power source; wherein at least a part of said second element is magnetic and is disposed within the coil, the second element being movable relative to the support under the influence of a magnetic field between said fourth and third positions .

This provides the advantage that the lock may be easily manipulated between its respective locked and unlocked conditions .

This provides the further advantage that the lock contains relatively few moving parts.

The lock may further comprise an access control element for selectively connecting the electromagnetic means to a power source, wherein when the electromagnetic means is not connected to a power source, the second element is in said fourth position, and when the coil is connected to a power source, the second element is in said third position .

This provides the advantage of a user being able to conveniently initiate the energising of the coil in order to gain access to the premises, when required.

This provides the further advantage of the lock being secure, in that it is not easily manipulated in order to gain unauthorised entry, since all that is exposed to a user is at least a part of the first element, with the remainder of the working parts of the lock being hidden away out of reach.

Said access control element may comprise a keypad, wherein when a correct combination is input into the keypad by a user, said electromagnetic means is connected to a power source.

This provides the advantage that the access control element is easy to use yet is also secure, with the

combination being able to be changed at regular intervals as required without any mechanical modification of the lock being required.

The lock may further comprise timing means which disconnects said electromagnetic means from said power source a pre-determined period of time after a correct combination is input into the keypad by a user.

This provides the advantage that the second element is automatically returned to its third position.

A preferred embodiment of the present invention will now be described,, by way of example only and not in any limitative sense, with reference to the accompanying drawings in which: -

Figure 1 shows a sectional plan view of a prior art combination of a lock with a key inserted therein;

Figure 2 shows a sectional view from one end of the prior art lock of Figure 1;

Figure 3 shows a sectional view from one side of a lock in a locked condition in accordance with a first embodiment of the present invention;

Figure 4 shows a sectional view from one side of a lock in an unlocked condition in accordance with a first embodiment of the present invention;

Figure 5 shows a perspective view from one end and a side, of an outer drive of a lock in accordance with a second embodiment of the present invention;

Figure 6 shows a perspective view from the opposite end to that shown in Figure 5, and a side, of an outer drive of a lock in accordance with a second embodiment of the present invention;

Figure 7 shows a view from one side of an outer drive of a lock in accordance with a second embodiment of the present invention;

Figure 8 shows a perspective view from one end and a side, of an inner drive of a lock in accordance with a second embodiment of the present invention;

Figure 9 shows a perspective view from the opposite end to that shown in Figure 8, and a side, of an inner drive of a lock in accordance with a second embodiment of the present invention; and

Figure 10 shows a sectional view from one side of a lock in an unlocking condition in accordance with a second embodiment of the present invention, incorporating the inner and outer drives of Figures 5 to 9.

With reference to Figures 3 and 4, a lock 1 comprises a support in the form of a hollow body portion 3, a first element in the form of a turn knob 5, and an electromagnetic means in the form of a coil 7 disposed within the body portion 3. The lock 1 further comprises a second element in the form of a shaft 11, wherein at least a part of the shaft 11 is disposed within the coil 7. The coil 7 of the electromagnetic means is connectable to a power source 23 via an access control element, which in this embodiment is a keypad 12. The

power source 23 may be a mains electrical supply or at least one battery, for example. It is to be appreciated however, that the lock 1 may comprise any suitable means for selectively energising and de-energising the coil 7. For example, the access control element may take the form of a push switch inside the premises, which may be operated by a user inside the premises to energise the coil for a predetermined period of time to enable an authorised person outside the premises to turn the turn knob 5.

The shaft 11 comprises a magnetic portion 13, wherein at least a part of the magnetic portion 13 is disposed within the coil 7. The magnetic portion 13 is of a circular cross-section. The shaft 11 further comprises a non-magnetic part 16 disposed at one end of the magnetic portion 13, and a locking element 15 attached to the nonmagnetic portion 16. The shaft 11 further comprises a key element 17 disposed at the opposite end of the magnetic portion to the non magnetic portion 16.

The locking element 15 is of non-circular cross section. In this embodiment, the locking element has a square cross-section. The turn knob 5 comprises a recess 19, which has a cross-section shaped to correspond with the cross-section of the locking element 15, which in the embodiment shown in Figures 3 and 4, is square. The longitudinal axis A of the shaft 11 is substantially parallel with the longitudinal axis B of the recess 19.

When the coil 7 is not energised, no current flows through the coil 7 and no magnetic field is produced. As can be seen from Figure 3 in particular, because no magnetic field is produced, the shaft 11 remains in its

fourth position, in which the lock is in its locked condition. In the fourth position, the locking element 15 does not engage the recess 19 of the turn knob 5, and is held out of engagement by means of a return spring 20 disposed within the recess 19. In this condition, as the turn knob 5 is turned by a user, the shaft 11 does not rotate with the turn knob 5, and as a result, the lock 1 does not open.

When a correct combination is inputted into the keypad 12 however, the coil 7 is energised by the power source 23, and current flows through the coil 7 in a certain direction which produces a magnetic field which moves the shaft 11 in a certain direction, in this embodiment, to the right as shown in Figure 3, against the bias of the return spring 20, resulting in the shaft moving to its third position in which the lock 1 is in its unlocked condition, as shown in Figure 4. Because the shaft 11 is moved to the right, the locking element 15 engages the recess 19 of the turn knob 5. The locking element 15 fits neatly into the recess 19 and because the cross section of both the locking element 15 and the recess 19 is non-circular, the locking element 15 and hence the shaft 11 as a whole, rotates with the turn knob 5. In view of this, as the turn knob 5 rotates, the key element 17 also rotates, which activates a mechanism (not shown) to retract a locking bolt (not shown) from a recess in a door for example (not shown) . The mechanism may be a typical pin tumbler lock such as that described in relation to Figures 1 and 2, with the key element 17 acting as a key which, when turned by means of the turn knob 5, enables the locking bolt to be retracted from the recess in a door.

The ^NN in-line" nature of the lock 1 resulting from the feature of the longitudinal axis B of the recess 19 and the longitudinal axis A of the 11 being substantially- parallel to each other enables the retro-fitting of the lock 1 into existing holes previously used for other lock mechanisms. Moreover, the size and shape of the lock 1, which has a substantially circular cross-section and may conveniently have a cross-sectional diameter of half an inch for example, enables the retro-fitting of the lock 1 into existing bores previously used for other lock mechanisms .

There is, however, a limit to the size of the force which can be applied by the coil 7 to the shaft 11 of the lock 1 of Figures 3 and 4. The size of the force which can be applied by the coil 7 is limited by the amount of current that the coil 7 is able to draw before it burns out. The size of the force which can be applied by the coil 7 is also limited by the size of the shaft 11 in that the greater the cross-sectional area of the shaft 11, the greater the force which may be applied by the coil 7. However, in the case where the lock 1 is intended to be retro-fitted into an existing bore, the lock 1 has to have a certain cross-sectional diameter, for example, half an inch. In this case, a greater cross-sectional area of the shaft 11 would result in the availablity of less space for the turns of the coil 7. The force applied by the coil 7 is more strongly dependent upon the number of turns than it is on the cross-sectional area of the shaft 11. It follows that, for a fixed cross- secitonal diameter lock 1, the greater the cross- sectional area of the shaft 11, the less the force which can be applied by the coil 7 to the shaft 11.

Despite this, the lock 1 is operated by a turn knob 5 instead of a typical key, and so the shaft 11 must be strong enough to withstand the relatively large forces generated by a user as they rotate the turn knob 5. This means that the shaft 11 must have a large enough cross- sectional area so that it does not snap as the turn knob 5 is rotated by a user.

As previously described, the shaft 11 is made from a magnetic portion 13 and a non-magnetic part 16. In view of the fact that the shaft 11 has to be able to withstand large forces when a user rotates the turn knob 5, the strength of the interface between the magnetic portion 13 and the non-magnetic part 16 becomes important.

The shaft 11 therefore has to have a large enough cross- sectional area to provide a strong interface between the magnetic portion 13 and the non-magnetic part 16, yet not be so large that the force applied by the coil 7 is compromised too much. An optimum cross-sectional area of the shaft 11 must therefore be chosen, which in practical terms results in the coil 7 only being able to apply a relatively small force to the shaft 11.

After the lock 1 has been operated by a user, in order for the shaft 11 to return to its fourth position in which the lock 1 is maintained in its locked position, the lock 1 is provided with a return spring 20 as described above. The return spring 20 urges the shaft 11 back to its fourth position once the coil 7 has been de- energised, to enable the turn knob to rotate freely without opening the lock 1.

In order for the lock 1 to work properly, however, the force of the return spring 20 which moves the shaft 11 back to its fourth position once the coil 7 has been de- energised must be less than the opposing force applied by the coil 7 when it is energised, since the coil 7 would otherwise not be able to move the shaft 11 even when energised .

Given that the coil 7 is only able to apply a relatively small force as described above, the force able to be applied by the return spring 20 has to be even less. This results in the return spring 20 being relatively weak.

When a user operates the lock 1 by way of rotating the turn knob 5 from its first position to its second position, in some circumstances the turn knob 5 may be inadvertently overturned. This can result in the various elements of the lock 1 becoming skewed. This in turn can result in the shaft 11 becoming "locked up," that is, becoming bound to various surfaces within the lock 1 in view of frictional forces within the lock 1 caused by the skewing of the various elements of the lock 1. This can result in the shaft 11 not returning to its fourth, i.e. locking, position after the coil 7 has been de-energised. In this way, the lock 1 can inadvertently remain in an unlocked condition when it should be in a locked condition .

If a user remembers to rotate the turn knob 5 back to its first position after the lock has been opened, however, this problem is alleviated since the skewed elements of the lock 1 can more easily re-align themselves when the turn knob 5 is in its first position.

The fact that the force applied by the return spring 20 is relatively small as described above only exacerbates this problem.

In view of the above, unless a user remembers to rotate the turn knob 5 back to its first position after the coil 7 has been de-energised, there is a risk that the lock may not have returned to its locked condition. In practical terms, this can cause a serious security flaw.

The lock 201 of Figures 5 to 10 overcomes or at least alleviates this problem by providing means for returning the turn knob back to its first position.

The lock 201 of Figures 5 to 10 is similar to the lock 1 of Figures 3 and 4, with like features represented by like numerals increased by 200. However, the lock 201 further comprises a drive assembly 263 comprising an inner drive 243 and an outer drive 227, which together help to ensure that the lock 201 does not inadvertently remain in its unlocked condition after the coil 207 has been de-energised. The inner drive 243 and the outer drive 227 together ensure that the turn knob 205 returns to its first position, to allow any skewed elements of the lock 201 to re-align themselves once again and therby facilitate the return of the shaft 211 to its fourth, i.e. locking, position.

Figures 5 to 7 in particular illustrate the outer drive 227. The outer drive 227 comprises a tubular element 229 having a circular transverse cross-section. The tubular element 229 has a first open end 231 and a second open end 233 which is threaded (not shown) on its outer

surface. The second open end 233 has an elongate abutting element 235 disposed thereon, the abutting element 235 having a D-shaped transverse cross-sectional area. The abutting element 235 comprises a planar contact face 237 and a curved face 239 which is also threaded (not shown) .

The curved face 239 of the abutting element 235 is flush with the second end 233 of the tubular element 229, and the abutting element 235 in effect covers half of the second open end 233 of the tubular element. Moreover, the planar contact face 237 of the abutting element 235 lies in a plane parallel to the longitudinal axis A of the tubular element 229. Two bores 241a and 241b are disposed in the planar contact face 237 to either side of the longitudinal axis A of the tubular element 229.

Figures 8 and 9 in particular illustrate the inner drive 243. The inner drive 243 comprises a tubular element 245 having a substantially circular cross-section. The tubular element 245 has a first open end 247 and a second closed end 249. The second closed end 249 has an elongate abutting element 251 disposed thereon, the abutting element 251 having a D-shaped transverse cross- sectional area. The abutting element 251 comprises a planar contact face 253 and a curved face 255.

The curved face 255 of the abutting element 251 is flush with the second closed end 249 of the tubular element 229, and the abutting element 251 in effect covers half of the second closed end 249 of the tubular element 245. Moreover, the planar contact face 253 of the abutting element 251 lies in a plane parallel to the longitudinal axis B of the tubular element 245. Two bores 257a and

257b are disposed in the planar contact face 253 to either side of the longitudinal axis B of the tubular element 245. The first open end 247 of the tubular element 245 comprises four connecting elements 259a, 259b, 259c and 259d disposed around its periphery.

The inner drive 243 and the outer drive 227 fit together inside the remainder of the lock 201 as shown in Figure 10, and as follows.

The inner drive 243 is of a predetermined size and shape to enable the tubular element 245 thereof to fit inside the tubular element 229 of the outer drive 227, and to enable the abutting element 251 of the inner drive 243 to fit through the second open end 233 of the outer drive 227. In this way, when the inner 243 and outer 227 drives are fitted together, the planar contact face 237 of the outer drive 227 and the planar contact face 253 of the inner drive 243 are disposed parallel to each other. This results in the bore 241a through the outer drive 227 being in-line with the bore 257a of the inner drive 243, and the bore 241b through the outer drive 227 being inline with the bore 257b of the inner drive 243.

Two compression springs (not shown) are disposed in the bores of the inner 243 and outer 227 drives, such that one of the compression springs bridges the bores 241a and 257a, and the other of the compression springs bridges the bores 241b and 257b. When the inner drive 243 and the outer drive 227 are at rest one inside the other and not placed under tension, the compression springs are at rest and maintain the planar contact faces 237 and 253 substantially parallel to each other.

The assembly 263 of the inner 243 and the outer 227 drives as described above is disposed between the shaft 211 and the turn knob 205. In particular, the assembly 263 is disposed such that the four connecting elements 259a, 259b, 259c and 259d of the inner drive 243 are able to locate in corresponding recesses (not shown) in the end 265 of the shaft 211. In this way, in the event that the coil 207 is energised and the inner drive 243 rotates, the shaft 211 rotates along with it. However, in the event that the coil 207 is de-energised and the inner drive 243 rotates, the shaft 211 does not rotate. Moreover, the threaded first end 231 of the outer drive 227 is attached to the turn knob 205 via the threads of the outer drive 227, such that as the turn knob 205 rotates, the outer drive 227 rotates along with it.

The lock 201 operates as follows.

In order to open the lock 201, a user carries out similar steps to those required to open the lock 1. In particular, the user first energises the coil 207, resulting in the shaft 211 moving to its third, i.e. unlocking, position in which corresponding recesses (not shown) of the shaft 211 engage the four connecting elements 259a, 259b, 259c and 259d of the inner drive 243.

Because the turn knob 205 is connected to the outer drive 227, when a user rotates the turn knob 205, the outer drive 227 rotates along with it and compresses one of the compression springs. For example, if a user rotates the turn knob 205 in a clockwise direction, the compression spring bridging the bores 241a and 257a could be the one to compress, and if a user rotates the turn knob 205 in

an anti-clockwise direction, the compression spring bridging the bores 241b and 257b could be the one to compress. By way of example only, the operation of the lock 201 will be described assuming that the turn knob is rotated in a clockwise direction. For the first few degrees of motion of the turn knob 205, as the compression spring is compressing, the inner drive 243 does not rotate. As the turn knob 205 is rotated further however, the planar contact face 253 of the inner drive 243 presses against the planar contact face 237 of the outer drive 227, and the inner drive 243 rotates along with the outer drive 227. Because the four connecting elements 259 of the inner drive 243 are engaged with the shaft 211, as the inner drive 243 rotates, the shaft 211 also rotates, thereby unlocking the lock 201.

Once the lock 201 has been opened, in the event that a user omits to return the turn knob 205 back to its first position after the coil 207 has been de-energised, and merely releases, but does not rotate, the turn knob 205, the action of the compression spring which is under compression, urges the outer drive 227 and hence the turn knob 205 back to its first position. This allows any skewed elements of the lock 201 to re-align themselves once again and thereby enable the return spring 220 to perform its function and disengage the shaft 211 from the inner shaft 243 to return the lock 201 to its locking condition .

It is therefore to be understood that the compression springs do not disengage the shaft 211 from the inner shaft 243, but instead urge the turn knob 205 back to its first position to enable the shaft 211 to disengage without "locking up."

In the event that the shaft 211 is not engaged with the inner drive 243, for example in the case where the shaft is in the fourth position, as the turn knob 205 is turned, the inner 243 and outer 227 drives rotate with the turn knob 205 but do not transfer rotational motion to the shaft 211.

In this way, the lock 201 protects against deliberate attempts to leave it in an unlocked state and also situations where the user forgets to rotate the turn knob 205 to its first position. In particular, the lock 201 does not rely upon a user having to turn the turn knob 205 back to its first position to allow the lock 201 to become locked once more.

The residual frictional forces (that is, those forces caused by the various elements of the lock 201 becoming skewed by overturning of the turn knob 205 in the first instance) are reduced when the turn knob 205 is returned to its original position. In this way, the lock 201 facilitates the return of the shaft 211 to its fourth (that is, locked) position by reducing the residual frictional forces .

The lock, two examples of which are described above, provides a secure way of preventing unauthorised access to a premises, yet also provides a convenient means of granting access to an authorised user, without the need for the user to carry a key. The lock is simple, compact, and is economical to manufacture, with relatively few moving parts. Moreover, the lock may easily be retro-fitted into the body portions of existing cylinder-type locks, without any significant modification

to the body portion being required. The "in-line" nature of the lock resulting from the feature of the longitudinal axis of the recess and the longitudinal axis of the second element being substantially parallel to each other enables the retro-fitting of the lock in this way. Moreover, the size and shape of the lock, which has a circular cross section having a diameter of half an inch for example, enables the retro-fitting of the lock in this way. The lock is therefore very quick and easy to install.

It will be appreciated by persons skilled in the art that the above embodiment has been described by way of example only, and not in any limitative sense, and that various alterations and modifications are possible without departing from the scope of the invention as defined by the appended claims .

For example, it is to be appreciated that twin cylinders may be used, whereby two coils are used, to enable access to be gained from either side of the door using the arrangement, two examples of which are described above. Alternatively, the lock may be arranged so that access may be gained from one side of door using the arrangement, two examples of which are described above, but access may be gained using a conventional key or turn knob from the other side of the door.

It is also to be appreciated that the direction of movement of the shaft may be reversed, such that the lock may be opened when the current flowing through the coil stops flowing, and the lock returns to its locking condition when the coil is energised. This may be termed as "fail unlocked." Moreover, in the situation where two

coils are used, one on either side of the door, one coil may be arranged to be "fail unlocked" whilst the other side may be "fail locked," which means that the lock may be opened only when current flows through the coil, such as is described above.