Commputerized combination lock

Abstract: A combination lock assembly (11) for a safe (1Ø) or the like is provided that is fully computerized and self powered. A rotary dial (12) is connected to a stepper motor/generator (14) to provide the electrical power to a capacitor (18) to power the system. The stepper motor/generator (14) also provides input signals in the form of a code sequence to a microprocessor (16) that processes the signals to initiate the operation of a drive motor (3Ø) to release a lock bolt (31) once the proper combination is dialed. A read only memory (ROM) (25) determines the proper combination from a combination storage means (26) and feeds the combination to the microprocessor (16) for comparison to the inputed signals from the dial (12). As each combination dialing sequence is begun, a random code initiator (4Ø) provides a different starting position in the sequence so that electronic or visual surveillance equipment cannot be used to surreptitiously used to obtain the combination. In order to thwart computerized input dialing to open the lock assembly (11), a dial speed sensitive lockout devi In order to thwart computerized input dialing to open the lock assembly (11), a dial speed sensitive lockout device (41) also controls the microprocessor (16). During the combination dialing, a display unit (35) presents th code and direction of movement of the sequence for observation by the person dialing the combination.

Description: The present invention relates to combination locks, and more particularly, to a computerized combination lock that is fully self contained. The technology of combination locks has changed very little over the past several decades. The basic design of such a lock includes a dial connected to a plurality of tumbler wheels for rotation. If the proper sequence of turning the dial is carried out by the operator, the gates in the tumbler wheels are aligned allowing the lever to drop in position for movement of the operating cam and bolt. Over the years, this type of lock has been improved several times and yet retains the same basic mechanism and function of the original combination locks. A typical combination lock includes 5⊘ - 75 machined parts of fairly close tolerance. The lock mechanism is thus relatively expensive, both in terms of material and labour to provide assembly and inspection. Furthermore, since the device is strictly mechanical, the parts are prone to wear and have a fairly high incidence of malfunction requiring repair by a locksmith. Also, with recent advances in listening devices and manipulators, these mechanical combination locks are now more subject to unauthorised opening. The mechanical structure of the lock inevitably provides metal-to-metal engagement sounds that can be recognised by the sophisticated listening devices that are available. Also, this traditional combination lock is susceptible to other types of electronic and visual surveillance to determine the combination. Thus, it is apparent that a new type of combination lock is desirable to replace the traditional combination lock and overcome the shortcomings of the prior art. A combination lock that is electronic rather than mechanical, and that can provide the protection against unauthorised opening is believed to be the best approach. UK Patent Specification GB-A-2,175,638 discloses a combination lock having a microprocessor which is used to display the combination being dialed, the lock itself being opened mechanically in a conventional manner. German Specification DE-A-3,208,818 discloses a self powered lock in which the use of a key is one of a number of alternatives. Accordingly, it is a concern of the present invention to provide a combination lock that is fully computerized and avoids the problems of the prior art combination locks, as outlined above. Another concern of the present invention is to provide an electronic combination lock assembly that is self powered so as to be completely self contained. An embodiment of the present invention provides a self powered electronic combination lock that has a rotary dial similar to a traditional combination lock in order to provide ease of operation and is interchangeable with these prior locks. It is still another concern of the present invention to provide a computerized combination lock assembly that is competitive in cost to manufacture in quantity with its mechanical counterpart, and is also rugged in design and highly reliable in operation. An embodiment of the present invention provides a computerized combination lock having a stepper motor/generator to provide the code sequence signals, as well as the electrical power for energizing the lock. Another embodiment of the present invention provides a lock that starts the dialing operation at a different location in the sequence each time and provides a lock out in the event that excessive speed is utilized in attempting to operate it. According to the present invention, there is provided a computerized combination lock assembly as set out in claim 1. Following these basic concepts, a lock that is competitive in cost, adapted for direct retrofit on existing safes or the like, and very reliable in operation can be manufactured. There is no need for an outside power source, or for batteries that are prone to run down. The lock assembly is in readiness for use even after long periods of inactivity that are common in safe operations. There are no mechanical parts to provide telltale signals and the need for maintenance is virtually eliminated. In accordance with another important aspect of the present invention, the dialing of a code sequence is initiated from a different starting point each time. This eliminates a security problem by insuring that electronic or visual surveillance of operation of the safe in order to obtain the combination is eliminated. No longer can an unauthorised person position the rotary dial at a known point and rely on the dial being started in the dialing sequence from that number in order to learn the combination. In the present invention, a random code initiation means picks a different point in the sequence each time the lock is powered. Thus, the dialing sequence is varied each time the lock is operated. As an additional security feature, the lock of the present invention is provided with means for interrupting the operation of the computer means in order to disable the lock under another condition indicating an attempt to gain unauthorized entry to the safe. Specifically, a component of the circuitry is provided to sense the speed of operation of the rotary dial during combination dialing and to interrupt the operation of the computer means when the speed is in excess of typical manual operation. This allows the lock to remain secure from opening when using computerized dialers or manipulation devices. An electronic digital display is provided integral with the lock dial. The display provides an indication of the number or other code that is presently represented by the position of the dial. In addition, the display means provides a direction arrow for indicating the present sequential direction of dialing by the operator. In operation, the stepper motor/generator is initially dialed rapidly by hand in either direction to generate electricity and store the electricity in the capacitor. A lock ready monitor in the form of an illuminated arrow, for example, is activated when sufficient power is available. Then the dial is turned starting from a random number for dialing the combination at a normal speed to duplicate the known code sequence and activate the lock operating means. If the combination dialing is too fast, indicating an attempt to open the lock by a manipulator device, the computer means locks out preventing opening of the safe. The programmable microprocessor is preferably a solid state device such as an Intel 8⊘C51. This microprocessor can be powered without difficulty by the stepper generator/motor and is capable of performing all functions mentioned. If desired, in order to obtain an enhanced output from the generator, a gear train can be interposed as part of the drive means between the input dial and the stepper motor/generator, thus providing additional speed and generating capacity. If desired, the gear train may be activated during the initial dialing action to generate the power and deactivated during the actual dialing operation. An an example, a 6:1 enhancement ratio can be provided; thus, the generating speed compared to the dialing speed is increased 6 times. A preferred embodiment of the invention will now be desribed in detail, by way of example only, with reference to the accompanying drawings, in which:- Figure 1 is a perspective view of a safe in which a combination lock of the present invention has been incorporated; Figure 2 is a top view of the dial of the lock shown on the safe of Figure 1; and Figure 3 is a diagram illustrating the computerized lock assembly with the electronic circuit shown in block form. Figure 1 of the drawings shows a typical locking container, such as a safe or a filing cabinet 1⊘ with a computerized combination lock assembly 11 shown on the top drawer. The lock assembly comprises a dial 12 on the outside of the safe, as well as the electronic circuitry on the inside, not shown in Figure 1 but shown schematically in Figure 3. As will be apparent, the dial 12 is operated by a rotary movement, and is connected through a suitable drive means 13 to a stepper motor/generator 14, which is preferably a miniature version, such as Type 17PS-C⊘⊘7-1⊘ manufactured by Minebea Company, Ltd. of Singapore. It is to be understood that other motor/generators including a custom made unit can be used as a substitute for this particular model and if desired, a gear enhancer (not shown) can be provided as a part of the drive means 13. The purpose of increasing the speed of the motor/generator 14 is to increase the power output during the operation for generating electrical power for operation of the electronic circuitry. This would preferably take he form of a typical gear train hay ing alternate relatively large gears driving relatively small gears and providing a gear ratio of approximately 6:1 or more. It is important to note that in accordance with an important aspect of the present invention that the stepper motor/generator provides two functions simultaneously that are a key part of the operation of the lock assembly 11. First, the stepper motor provides signal pulses that generate a code sequence in response to the rotary motion of the dial 12. These pulses are fed along line 15 to the central computer means of the circuit; namely, a microprocessor 16. At the same time, the motor/generator 14 serves as the power means for generating electriciy for feeding along a line 17 to charge a capacitor 18. In turn, the microprocessor 16 is activated by stored power from the capacitor 18 along a line 19. A lock ready monitor 18a senses the avaiable power stored in the capacitor 18 and when sufficient to operate the lock assembly 11 signals the operator. The microprocessor 16 is preferably a solid state programmable device; such as a 8⊘C51 chip manufactured by Intel Corporation of Santa Clare, California. This microprocessor chip is particularly suited for relatively low power operation, and for combining the several desirable features of the lock assembly 11 of the present invention. However, it is to be understood that other microprocessors or a custom made chip can be utilized in accordance with the broad aspects of the present invention. It is only necessary that the computing capacity and power requirements be suitable for carrying out the functions as described with respect to the lock assembly 11. In order to provide the microprocessor 16 with a selected combination for comparison to the code sequence signal from the stepper motor/generator 14, a read only memory 25 is provided. The combination is retrieved from a combination storage 26, preferably an electrically erasable programmable chip, such as Model 93C46 of International C mos Technology, Inc. of San Jose, California. The signal corresponding to the proper combination is fed to the microprocessor along a line 27 during each computing operation. By comparing the combination from the storage 26 with the code sequence from the stepper motor/generator 14, the microprocessor 16 can determine when the requirements for opening the safe have been met. In order to carry out the command for operating the lock assembly 11, a drive motor 3⊘ is provided to be activated in response to the signal along a line 31. Preferably, the drive motor 3⊘ is of the electromagnetic type, such as a rotary or linear solenoid. The operating means also includes a slide bolt 32 activated by the drive motor 3⊘. A display unit 35 activated by the microprocessor 16 is physically mounted in the stationary rim of the dial 12 (see also Figure 2). A suitable choice is the Model HD47⊘⊘ digital display of Hitachi Corporation, Japan. The code is provided by numbers, as represented by the number N displayed in Figure 2 (note numeral "63" as shown). In addition, directional arrows A₁, A₂, are provided to indicate to the operator the direction of movement of the sequence upon rotation of the dial 12. As indicated in Figure 2, the arrow A₁ pointing to the left is activated (as oriented in Figure 1) thus indicating a declining sequential movement of the numerals. This arangement is particularly advantageous in allow ing operators who are familiar with operating a traditional combination lock to feel comfortable in operating the computerized combination lock of the present invention and to substantially reduce the training time for operators. Each time the lock assembly 11 is to be operated for combination dialing, it is desirable that the number N that first appears on the display unit 35 is a random number. It has been didscovered that it this is done, the chances of successful electronic or visual surveillance to surreptitiously obtain the combination are substantially reduced. In other words, if a different starting position is used in the sequence each time the dial 12 is operated to input the combination, this changes the overall sequence and prevents surveillance from successfully deciphering the combination of the lock assembly 11. Accordingly, a random number or code initiator 4⊘ is provided for connection to the microprocessor 16 to select a different number each time the dial 12 starts a new combination dialing operation. In other words, for one dialing operation, the first number that appears in the sequence might be the number 63, as shown in Figure 2; whereas, the next time a dialing operation is initiated, the number may be 36, or any other number built into the system. If desired for greater security a random number may be selected each time the dial direction changes during the combination dialing. In order to further thwart unauthorized opening of the lock assembly 11, a lock-out unit 41 that is dial-speed sensitive is provided. In the event that the dial 12 is operated at a speed greater than would be required to work a combination in approximately 1⊘ seconds, which is the limit for normal manual input, then the microprocessor 16 is locked out or interrupted so that the operating means 3⊘, 31 becomes inoperative. This assures that the lock assembly 11 cannot be operated by manipulation devices that are computer controlled simply rotating the dial 12 rapidly through all possible combinations, and thus gain unauthorized entry to the safe 1⊘. Both the code initiator 4⊘ and the lock-out unit 41 may be software operated, and all of the electronics can be incorporated into the single custom made microprocessor, if desired. In summary, the results and advantages of the lock assembly 11 of the present invention can now be more fully realized. The manual input through the dial 12 provides both the code sequence for opening as well as the power to activate the electronic circuitry. This desirable result comes from using the combined functions of the single stepper motor/generator 14. The microprocessor 16 obtains the desired combination from the ROM 25 and compares it to the dialed code sequence, and when a match is made, the drive motor 3⊘ is actuated to effect opening of the safe 1⊘ or the like. A display unit 35 provides the numerals N with the directional arrows A₁, A₂ to indicate either descending or ascending sequence movement. The random number initiator 4⊘ provides for a different number to start the dialing sequence or each time there is a change in direction of the dial. The dial-speed sensitive lock-out unit 41 interrupts the opening process if a speed of operation greater than normal manual speed is detected. It will also be recognized that in addition to the superior performance of the lock assembly 11, the construction is such as to reduce significantly the cost of manufacture as compared to the traditional mechanical lock. Also, since mechanical components are virtually eliminated, the need for maintenace is substantially reduced.

Claims: A computerised combination lock assembly (11) for a locking container (10) comprising: means (14) including a rotary dial (12) for providing code sequence signals in response to the rotary dial; computer means (16) for receiving the code sequence signals; and power means (14,18) for providing electricity for activating the computer; characterised in that the lock assembly further comprises: memory means (25,26) for storing and supplying data signals representing a selected combination; operating means (30,32) responsive to the computer means (16) to open the container when said code sequence corresponds to said selected combination; drive means (13) connecting the rotary dial to the power means, whereby the combination lock assembly is self-powered. A lock assembly as in Claim 1, characterised in that the power means includes a stepper motor/generator (14) connected to the dial (12) for rotary motion. A lock assembly as in Claim 2, characterised in that the power means further includes a capacitor (18) for storage of electrical energy between the generator (14) and the computer means (16). A lock assembly as in any one of Claims 1 to 3, characterised in that the memory means includes a combination storage means (26) and a read only memory (25) to provide the combination to the computer means (16). A lock assembly as in any one of Claims 1 to 4, further characterised by random code initiation means (40) for providing to the computer means (16) a different code to start a new sequence during manipulation of the input means (12). A lock assembly as in any one of Claims 1 to 5, further characterised by means (41) for locking out the operation of the computer means (16) in response to sensing a speed of combination dialing in excess of manual operation of the input means. A lock assembly as in Claim 1, further characterised by an electronic digital display means (35) integral with the dial (12). A lock assembly as in Claim 2, characterised in that the stepper motor/generator (14) includes the means for providing code sequence signals in response to the input means. A lock assembly as in any one of Claims 1 to 8, characterised in that the computer means includes a programmable microprocessor (16).

Inventors: HARVEY MICHAEL PATRICK, MILLER JAMES CLAYTON, HARVEY, MICHAEL PATRICK, MILLER, JAMES CLAYTON
Applicants: C & M TECHNOLOGY INC, C & M TECHNOLOGY, INC.
Application year: 1989
Main classification: E05B49
IPC codes: E05G1, E05B37, G07C9, E05B49