Patent Abstract:
An electromechanical cylinder lock-key combination includes a cylinder housing and a cylinder core rotatably arranged in the cylinder housing and having a key-way for receiving a key. A plurality of key actuated moveable blocking elements block the rotation of the cylinder core unless a correct key is inserted in the key-way. An optical code reader in the lock reads an optical code element provided on an inserted key. At least one of said blocking elements functions as a bar element barring insertion of the key into the key-way unless a correct optical code element is provided on the key. By using at least one of the mechanical elements already present in the lock as part of the electronically controlled blocking mechanism, in combination with the use of an optical code requiring no moveable parts for the reading thereof, space requirements in the lock device are kept to a minimum.

Full Description:
FIELD OF INVENTION 
   The present invention relates generally to electro-mechanical key and lock devices and more particularly to an electro-mechanical cylinder lock-key combination using an optical code, such as a holographic code or a bar code provided on the key. 
   BACKGROUND 
   It is previously known a variety of lock devices that make use of electronically controlled elements for increasing the security of the lock. However, the demand for lock systems with a high level of security is constantly increasing. 
   Many prior art electro-mechanical lock devices rely on a power source external to the lock device for powering the electronic circuitry of the device. This poses a problem, particularly when fitting a new electro-mechanical lock in an existing installation. 
   One way to avoid this problem is to provide a replaceable battery either in the lock device or in the keys used with the lock device. However, the replacement of the battery is often a cumbersome operation. Furthermore, the battery takes up valuable space, irrespectively of whether it is provided in the lock or in the key. Also, batteries constitute an environmental hazard. 
   Another problem with today&#39;s electro-mechanical lock devices is that they must include not only mechanical locking elements but also the electronic circuitry and elements controlled by the electronic circuitry. All these elements must fit into the space defined for conventional all mechanical locks. The size of the electronic part of the locking mechanism must therefore be kept to a minimum. 
   Yet another problem with prior art electro-mechanical lock devices is that when the key having correct mechanical code is inserted then all key-actuated moveable blocking elements are moved to non-blocking position; only the electro-mechanical blocking element remains to prevent the rotation of the cylinder core. 
   SUMMARY OF THE INVENTION 
   An object of the present invention is to provide a key and lock device of the kind initially mentioned, wherein a high degree of security is obtained while the space requirements are kept to a minimum. 
   The invention is based on the realisation that the movement of at least one of the blocking elements conventionally found in a mechanical lock can be prevented by the provision of an optical code element on the key. 
   According to the invention there is provided an electro-mechanical cylinder lock-key combination as defined in the appended claims. 
   By using at least one of the mechanical elements already present in the lock as part of the electronically controlled blocking mechanism, in combination with the use of an optical code requiring no moveable parts for the reading thereof, space requirements in the lock device are kept to a minimum. 
   In a preferred embodiment, the optical code element is provided in the form of a hologram. This provides for a very high level of security thanks to the huge amount of possible codes and the difficulty in copying the key. 
   In another embodiment, a reflective bar code is provided as optical code on the key. 
   Further preferred embodiments are defined by the dependent claims. 

   
     BRIEF DESCRIPTION OF DRAWINGS 
     The invention is now described, by way of example, with reference to the accompanying drawings, in which: 
       FIG. 1  is an overall perspective view of a key and lock device according to the invention; 
       FIG. 2  is a perspective view of a key according to the invention; 
       FIG. 3  is a top sectional view of the device shown in  FIG. 1  before insertion of a key; 
       FIGS. 3   a  and  3   b  are cross-sectional views of the device shown in  FIG. 3  taken along the lines IIIa—IIIa and IIIb—IIIb, respectively, in  FIG. 3 ; 
       FIGS. 4–7  are top sectional views of the device shown in,  FIG. 1  during different stages of insertion of a key; 
       FIGS. 6   a  and  7   a  are cross-sectional views taken along line VIa—VIa in  FIG. 6  and line VIIa—VIIa in  FIG. 7 , respectively; 
       FIG. 8  is a top sectional view of the device shown in  FIG. 1  with a fully inserted key; 
       FIG. 8   a  is a cross-sectional view of the device shown in  FIG. 8  taken along the line VIIIa—VIIIa in  FIG. 8 ; 
       FIG. 9  is a top sectional view of the device shown in  FIG. 1  with an inserted key having incorrect optical code; 
       FIG. 9   a  is a cross-sectional view of the device shown in  FIG. 9  taken along the line IXa—IXa in  FIG. 9 ; 
       FIG. 9   b  is a sectional side view showing the position of an inserted key; 
       FIGS. 10 and 11  are cross-sectional views of the device according to the invention showing the interaction between a special pin tumbler and a pin blocking element; and 
       FIG. 12  is a perspective view of an alternative key according to the invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   In the following a detailed description of preferred embodiments of the present invention will be given. 
   In  FIG. 1 , an overall perspective view of an electro mechanical cylinder lock-key combination  1  according to the invention is shown. The combination comprises a generally cylindrical cylinder housing  10  and a key  20  inserted into a key-way of a cylinder core  30  rotatably provided in the cylinder housing. By means of rotation of the key, a campiece  12  is actuated so as to act on a follower of a lock device. The cylinder housing  10  has the same general shape as conventional cylinder housings and the lock cylinder according to the invention can thus replace already installed all-mechanical lock cylinders. 
   The key  20  is shown in its entirety in  FIG. 2 . It has a conventional shape and comprises a grip portion  22  and a bit portion  24 . The bit portion has an upper code surface  26  arranged to cooperate with tumbler pins provided in the lock cylinder. 
   On a side surface of the bit portion there is provided an elongated holographic image or hologram  28  having a surface being essentially flush with the side surface of the bit portion so as not to interfere with the insertion of the key into the cylinder core  30 . The hologram functions as an additional code and a key must thus have both a correct mechanical code, i.e., code surface  26 , and optical code, i.e., hologram  28 . This adds a further level of security as compared to an all-mechanical lock. 
   A top sectional view of the lock cylinder is shown in  FIG. 3 , wherein it is seen how the elongated cylinder core  30  is provided in the cylinder housing  10 . A key-way  32  is provided centrally in the cylinder core so as to receive the key  20 . Centrally aligned in the cylinder core are also six pin tumbler chambers  34 – 39 , wherein the five front chambers  34 – 38  each contains conventional pin tumblers acting as blocking elements when a key having incorrect mechanical code is inserted in the cylinder. An example of pin tumbler is given in  FIG. 3   a , showing a top pin  34   a  and a bottom pin  34   b.    
   The inner pin tumbler chamber  39  contains a conventional top pin  39   a  and a special kind of bottom pin, designated  39   b  in  FIG. 3   b . This pin is provided with a circumferential waist or indent  39   b ′ arranged to receive an outer portion of a pin-blocking element  40  provided at the outer end of a piezo-electric bender  42 . This bender is arranged to move the pin blocking element  40  into and out of engagement with the waist portion  39   b ′ of the special pin  39   b . This function will be further explained below. 
   The inner end of the piezo-electric bender  42  is fixed so as to make the outer end move when current flows through the piezo-electric bender. 
   By using the inner pin tumbler as electronically controlled blocking element, several advantages are obtained. Firstly, the time from when the key  20  enters the cylinder core  30  to when it contacts the inner pin tumbler is long enough for the electronics to process the information in the optical code and control the pin tumbler  39   a ,  39   b  accordingly. Secondly, the piezo-electric bender  42  can be made long enough so as to displace the pin-blocking element  40  out of engagement with the special pin tumbler. 
   The electrical operation of the lock cylinder is controlled by means of an application specific integrated circuit (ASIC)  44 . This ASIC is electrically connected to an optical unit comprising a laser diode  46  and an array of opto-electronic sensors  48  for recording an incoming laser beam. This will be fully described below with reference to  FIG. 4 . 
   On the opposite side of the key-way from the opto-electronic components there is provided a striking pin or “hammer”  50  running in a cylindrical cavity  52  in the cylinder core  30 . The hammer is provided with a finger  54  arranged to cooperate with the tip of the key  20  during insertion thereof and is spring-biased towards the front end of the cylinder core  30  by means of a helical spring  56 . 
   An electric capacitor  58  is connected to the electrical power consuming components of the lock cylinder and is provided for storing electric energy by these components. Finally there is provided a piezo-electric generator  60  in the cavity  52 . The generator comprises piezo-electric ceramic, i.e., a material made of crystalline substance, which creates charges of electricity by the application of pressure and vice versa. The generator functions in the following way. In its resting position shown in  FIG. 3 , the hammer  50  is pressed against the generator  60  by means of the force exerted by the helical spring  56 . When the hammer is moved from this position by the key tip, se  FIG. 4 , this force is removed and the generator  60  thus produces a weak electric current, which is supplied to the ASIC  44  and the laser diode  46 . The current thus functions as a “wake up signal” for the ASIC, which is essentially powered by the capacitor  58 . When the hammer is returned to its original position, as will be described below with reference to  FIG. 7 , mechanical energy is again converted into electric energy, charging the capacitor  58 . 
   If so desired, the helical spring  56  can be given a characteristics adapted to provide defined force on the hammer. 
   The operation of the lock cylinder will now be explained. In  FIG. 4  there is shown how the key is inserted into the key-way. The hammer  50  is moved from its resting position shown in  FIG. 3  when the tip of the key bit reaches the finger  54  thereof. The electric energy thus created by the generator  60  is directed to the ASIC  44 , thereby making it operative. The laser diode  46  is then controlled by the ASIC to emit a laser beam in the direction of the side of the key bit provided with the hologram containing the holographic code. During insertion of the key  20 , the hologram breaks up this laser beam in between 1 and 32 sub-beams and these are reflected onto the opto-electronic sensors  48  in dependence of the holographic code. In other words, during insertion of the key  20  the 32 bit optical code contained in the hologram is recorded by the sensors  48  and this code is transmitted to the ASIC  44 . 
   By reading the optical code while the key is moving, valuable time is saved and the user inserting the key into the lock cylinder will experience no time delays for reading and evaluating the optical code. 
   The correct optical code of the cylinder is stored in the ASIC. This correct code is compared with the code recorded by the sensors  48  and if they are identical, then the laser diode  46  is switched off and the pin-blocking element  40  is moved to a non-blocking position, as will be explained below. If the codes differ from each other, the laser diode is still switched off but the pin-blocking element  40  is left in blocking position. 
   In  FIG. 5  there is shown how the key  20  has been inserted further into the cylinder core  30 , bringing the hammer  50  with it, compressing the helical spring  56 . When the helical spring is compressed further, the force exerted by it on the hammer makes the finger  54  of the hammer  50  slip off the key tip and take the position shown in  FIG. 6   a . During this operation, the entire hammer  50  is turned. The spring force from the helical spring  56  then returns the hammer to its original position shown in  FIG. 3 . 
   If the key  20  inserted into the cylinder has a correct optical code, the ASIC connects the generator  60  and the piezo-electric bender  40 . When the hammer is released and hits the piezo-electric generator, the generator generates a voltage, which is directed across the piezo-electric bender  42 . The generator  60  and the bender  42  thereby form a matched electrical circuit, providing a reliable actuator. The voltage across the piezo-electric bender makes it bend and thereby moves the pin blocking element  40  out of engagement with the special blocking pin  39   b . With the pin blocking element in this position, the pins  39   a ,  39   b  function as the ordinary pins  34   a,b–   38   a,b . Thus, the tip of the key  20  pushes the pins  39   a,b  upward, see  FIG. 10 , and the key can be fully inserted into the cylinder core to the position shown in  FIG. 8 . If the mechanical key code  26  provided on the key is correct, then all pin tumblers have been moved to a position wherein the shear line between top and bottom pins is aligned with the shear line between the cylinder housing  10  and the cylinder core  30 . This enables rotation of the cylinder core  30  and thereby unlocking of the lock provided with the lock cylinder  1 . 
   When a correct key is withdrawn from the position shown in  FIG. 8 , the piezo-electric bender is returned to its straight shape. 
   If the optical code provided on the key is incorrect, the pin blocking element remains in engagement with the special pin  39   b  and the special pin tumbler  39   a,b  is stuck in position, see  FIG. 11 . This in turn prevents the key  20  from being fully inserted into the cylinder core and it can only be inserted to the position shown in  FIGS. 9 and 9   b.    
   As appears from  FIG. 9   b , in this position of the key, not only the pin tumbler  39   a, b  that is controlled by the optical code but also all other pin tumblers block rotation of the cylinder core. This is a significant advantage, as a key provided with correct mechanical code but with incorrect optical code releases no blocking elements in the lock cylinder. 
   The pin-blocking element  40  is shown in detail in  FIG. 11  in the position wherein a user of a key having incorrect optical code tries to push the key to its fully inserted position. The pin-blocking element is attached to the piezo-electric bender  42  through an aperture therethrough and is provided with a tapering flange  40   a  in the direction of the pin  39   b . Its outer portion ends in a tip  40   b  dimensioned so as to fit into the waist portion  39   b ′ of the special pin  39   b . The pin-blocking element  40  is normally kept level by means of the spring force provided by a helical spring  40   c.    
   Returning to  FIG. 9   a , if a user of a key lacking correct optical code urges the key to the special blocking pin  39   b , this pin is moved slightly upward to an extent allowed by the tilt of the pin blocking element  40 . In the position shown in  FIGS. 9   a  and  11 , the flange  40   a  cooperating with the cylinder core material provides a self-locking arrangement, pressing the pin-locking element towards the special blocking pin  39   b . This provides a mechanical arrangement adapted to withstand the forces from a hammer hitting the key grip, for example. 
   By using piezo-electronic components, large movable masses in the electronically actuated lock mechanism are avoided, increasing the speed by which the unlocking can be effected and saving space. 
   A preferred embodiment of an electromechanical cylinder lock-key combination and a key according to the invention has been described. The person skilled in the art realises that this could be varied within the scope of the appended claims. Thus, although a hologram has been described as the preferred optical code element, it will be appreciated that other forms of code elements could be used as well. An example of an alternative embodiment is given in  FIG. 12 , wherein a reflective bar code  28 ′ is provided on the side surface of the bit portion. If this kind of optical code is used, the above described laser diode  46  is replaced by a conventional light emitting diode (LED). 
   Alternatively, the optical code could be provided not on the side surface of the key bit but on the underside thereof. 
   In its preferred embodiment, the inventive lock cylinder is provided with a special blocking pin tumbler arranged to be released by a piezo-electric bender upon detection of a correct optical code. The piezo-electric bender could of course be replaced by another kind of actuator, such as a solenoid etc. 
   A lock cylinder having six pin tumblers has been described. It will be realised that a cylinder having a different configuration than the embodiment shown can be used without departing from the inventive concept. 
   By providing a piezo-electric generator, the battery found in many electromagnetic locks is dispensed with. However, the inventive idea is also applicable to a lock having an internal battery or being externally powered. 
   In the preferred embodiment, the inner pin tumbler is used as the electronically blocked element. However, other pin tumblers can be blocked either in addition to or instead of the inner pin tumbler. 
   The electronic lock mechanism has been shown controlled by means of an ASIC. Any micro controller or other processing unit can of course be used for that purpose.

Technology Classification (CPC): 8