Abstract: The invention concerns a lock and related key of the electronic type, which bases the unlocking of the lock on the matching of codes memorized in the lock and in the key, making it possible for one key to unlock a considerable number of pre-selected locks.

Abstract: The circuit arrangement has a key for the serial feeding in of the code signals and is equipped with electronic arrangements for the storage of the code and for the processing of the signals. In the beginning or at the end of each sampling, a signal is produced and the temporal intervals between these signals are identified as "long", "medium" or "short." The sequence of these signal intervals, that is, the signal pauses, is compared with the stored code.Such a code may be remembered with particular ease as the rhythm of a song or as a melody and is accordingly very personal code. The feeding-in of the code and especially the decoding is acomplished "blindly", that is without return communication.In order to carry out the individual functions, separate construction stages or a microcomputer can be used.

Abstract: An electronic combination lock for luggage and the like comprises a microcomputer, a display having a plurality of display locations, and a plurality of push buttons, one being associated with each display location. Each push button advances its associated display location through a sequence of digits and enables selection of a desired digit for display. A displayed set of digits is compared with a stored predetermined set of digits, and a bistable electromagnetic latch is operated to open the lock when the sets of digits match.

Abstract: There is provided a keyless entry system in which a permanent code, or first code, and a user's code, or second code are used. The second code is presettable in conjunction with use of the first code. When the first code is inputted, the system gets ready for presetting a desired number of code elements consituting the second code. According to the invention, the system is provided with a circuit for variably presetting the number of the code elements, which circuit is responsive to the first code to vary the presetted number of the second code elements to that inputted following to the input of the first code. Preferably, the keyless entry system further includes a theft prevention circuit which inhibits input of a code for a given period of time when wrong codes are inputted more than a predetermined number of times.

Abstract: A card key switch including a card key obtained by forming notches, in accordance with a key code, on opposite side edges of a card or a card casing for accommodating the card, a key cylinder formed with a key slot, a plurality of tumblers, a light emitting element and a photo detector operatively associated with the light emitting element so as to generate an electric signal in response to detection of light from the light emitting element.

Abstract: An electronic door locking system for an automotive vehicle which locks the vehicle doors when the driver depresses push-button type switches installed at an appropriate position on the outside of an automotive vehicle in accordance with a predetermined code, only after the vehicle has been kept parked in a safe state, e.g. after all the vehicle doors have been closed perfectly and/or when the parking brake has been applied to the vehicle securely or the gear shift lever has been set to Park position securely. The system according to the present invention comprises, in particular, a device for detecting unsafe-park states and another device for disabling the lock command signal in response to the unsafe-park signal from the detecting device, in addition to the conventional electronic door locking system.

Abstract: A door locking system for an automotive vehicle including an anti-theft automatic door locking apparatus by which the door can automatically be locked a fixed time period after the door has been closed in the case where an ignition switch is open and the ignition switch is left at the steering-lock position. The door locking system according to the present invention comprises an ignition switch for detecting the state in which the engine is not operating, a door-close switch for detecting the state where the vehicle doors are closed, a timer for delaying the automatic locking of the doors for a fixed time period, and an AND gate, in addition to the conventional door locking system.

Abstract: The invention relates to a coded locking device actuated by successive pushes on two buttons. This device comprises means for converting the pushes on the two buttons into electrical pulses emitted respectively along two channels and an electronic unit adapted to identify the pulse trains successively emitted in the two channels, to count the numbers of pulses of the different successive trains, to compare each sequence of pulse trains with a memorized reference or code sequence and to emit an unlocking signal S if the two sequences are identical. To form each sequence of actual pulses, the user can start by pressing either one of the two buttons.

Abstract: The central locking system adapted especially to motor vehicles comprises a plurality of electric locking drives and a time control circuit triggerable by at least one control switch in switching over from a first switch position to a second switch position. The time control circuit switches on the locking drives for a predetermined time duration in a predetermined drive direction. A switch signal generator controlled by the control switch generates a first two-level control signal the control levels of which represent the switch positions of the control switch. The switch signal generator in the switching over of the control switch from the first switch position into the second switch position triggers a ramp signal generator which delivers a ramp signal varying in time with constant direction from a predetermined initial level.

Abstract: An electronical locking/unlocking system by which a door can be unlocked when a single switch is depressed repeatedly by an operator in time with a musical rhythm which he knows or in accordance with a Morse-type code. The electronical locking/unlocking system according to the present invention comprises a single switch for generating a predetermined series of on-time interval and off-time interval signals, a first counting unit for counting the on-time intervals, a second counting unit for counting the off-time intervals, a memory unit for previously storing reference ratios of on-time intervals to off-time intervals, a calculating unit for dividing the counted on-time intervals by the counted off-time intervals, a comparating unit for comparing the calculated values with the reference values, a third counting unit for counting the number of accurate on/off ratios up to a predetermined number, and an unlocking actuator.

Abstract: A digital-code operated circuit for an electronic lock is provided. The circuit comprises a switch means to alternatingly close and open a circuit to provide pulses of specific numbers and groupings. The groupings constitute digits and sequence of digits respectively, converting means to convert the number of the pulses per digit and the number of the groupings per digit sequence from serial to parallel. The circuit also comprises discrimination means to distinguish between discrete pulses constituting a single digit and between complete digits constituting a digit sequence, memory means to store the data produced by the converting means, program means in which the digital code can be set, and verification means to verify whether the pulses provided by the pushbutton means produce digit sequences conforming to the digital code as set in the program means, wherein a signal for the unlocking of the lock is provided only by conformance with the code.

Abstract: A keyless vehicle device actuating system for an automotive vehicle combined with an electronic vehicle door unlocking system. Since the vehicle devices, in particular, the engine starting motor can be rotated only when the driver first opens the vehicle doors in accordance with a predetermined code, secondly depresses a plurality of push-button switches arranged within the passenger compartment in accordance with another predetermined code and lastly depresses a starting switch, even if the vehicle doors are opened incorrectly, it is possible to prevent the vehicle which can be started by only depressing a starting switch from being stolen easily. The system according to the present invention comprises a vehicle device actuating signal generating section similar to a door unlocking signal generating section, an ANDing section and a plurality of devices actuated in response to the ANDed signal, in addition to an ordinary electronic door locking system.

Abstract: In the present invention, the control system comprises a number presetter in the form of a switch board including a certain number of, say five, pushbutton switches. By depressing them sequentially and selectively in a desired order, an arbitrarily selected number code signal can be delivered. This number code signal may have five or seven digits, as an example. Further, there is a first memory which has a predetermined memory content representing a permanent code signal specifically selected at a vehicle manufacturing stage which is unique to the automotive vehicle under consideration. As an example, this may be "5 - 1 - 4 - 3 - 2 - 1- 5". Further, there is a first comparator adapted for comparison of the permanent memory content in the first memory, with an arbitrary number code signal generated at and delivered from the switch board. If there is coincidence between the both signals, the switch board's outlet signal is conveyed to a second memory.

Abstract: An automotive vehicle electronic door locking system returns vehicle devices left in operation to an original disabled condition whenever the driver locks the vehicle doors by depressing at least one of a plurality of coded push-button type switches installed at an appropriate position on the outside of an automotive vehicle. Since the vehicle devices, such as a power-operated car-radio antenna, small lights, a room light, etc., are automatically returned to an original disabled condition, it is possible to park the vehicle safely after the vehicle doors have been locked. The vehicle devices are actuated to the original disabled condition thereof in response to a lock command signal, in addition to the conventional electronic door locking system.

Abstract: An improved electronic key for use in combination with an electrical receptacle adapted to receive the key wherein switch contacts on the key are designed for making electrical contact with corresponding receptacle contacts when the key is turned in the receptacle to an "on" position only after the other key contacts make electrical contact with the corresponding receptacle contacts. Conversely, the switch contacts are the first to break electrical contact when the key is turned past the "on" position in either direction.

Abstract: An electronic lock for a door includes a built-in generator (20) for generating electrical energy for operating an electronic code recognition circuit and energizing a lock-release solenoid when appropriate. The generator (20) is linked to the door handle spindle (31) via a resilient mechanical energy storage device (24) which is "wound up" during the initial part of turning of the handle and tripped at a predetermined point to release stored energy into the generator (20).

Abstract: A lock release mechanism which is operable in conjunction with a locking device on an access means, such as a hood into a portion of a vehicle, preferably an automotive vehicle. The lock release mechanism comprises an outer housing having a shiftable locking element therein. The shiftable locking element is locked when a shiftable plunger, such as a wedge, is biased into locking position. The lock release mechanism also includes a solenoid which is energized to remove the plunger from the locking position. When the plunger is removed from its locking position, the lock device on the access means can be operated.The lock release mechanism is preferably designed for use in vehicles of the type equipped with a safety interlock system and which is electrically operable pursuant to the introduction of a preselected code through a plurality of manually operable input switches.

Abstract: An electronic door locking system for an automotive vehicle with which vehicle doors can be locked, by depressing a proper push-button type switch representative of a predetermined door-locking octal digit, only when an ignition key is not left in the ignition keyhole. Therefore, it is possible to lock vehicle doors without leaving the ignition key in the keyhole, with the result that the vehicle can be prevented from being stolen by a thief when parked. The electronic door locking system according to present invention includes a device for detecting the presence of the ignition key left in the ignition keyhole and outputting a signal to inhibit a door-locking command signal from being applied to a door lock actuating solenoid, in addition to the conventional electronic door locking system.

Abstract: An electronic combination lock uses a single pair of contacts which are connected to a door opening actuator such that a code may be input into the electronic combination lock by sequentially moving the door opening actuator in a predetermined pattern. The device is especially suitable for use in car doors such that the appearance of a conventional car door is maintained, but the ease of entry with an electronic combination lock is provided. A detecting circuit detects whether the car door pushbutton or movable handle is moved in the correct timed sequence. The initial movement of the pushbutton or door handle is used for starting a timer running and initiating the supply of power to the detecting circuit. A pulse generator outputs a series of pulses which are fed into a pulse sequencer. The pulse sequencer is used for gating the switch position (open or closed) to one of a number of parallel disposed registers in a latching circuit.

Abstract: An electronic door locking system for an automotive vehicle with which vehicle doors can be locked, by depressing a proper push-button type switch representative of a predetermined door-locking digit, only when an ignition key is brought near the switch. Therefore, it is possible to lock vehicle doors without leaving the ignition key in the keyhole, with the result that the vehicle can be prevented from being stolen by a thief when parked. The electronic door locking system according to present invention comprises means for detecting the presence of the ignition key brought near the switch and an AND gate for passing a locking command signal to a door lock/unlock actuating solenoid only when the presence of the key is detected, in addition to the conventional electronic door locking system.

Abstract: A tamper-resistant security system for and method of operating and installing the same are disclosed for electronically controlling an access device such as a garage door. A manual keyboard encoder mounted exteriorly on a garage door jamb is operative for generating coded electrical signals, including a predetermined sequence of coded electrical signals required to move the garage door from a closed to an open position. A control-processor unit mounted within the interior garage area is operative for detecting the coded signals, and for moving the garage door from the closed to the open position in response to detection of the predetermined coded signal sequence. A single pair of electrical conductors interconnects the encoder and the control-processor unit. The transmission of the predetermined coded signal sequence over the single pair of conductors deters intruders from compromising system security, and also simplifies the installation.

Abstract: An anti-theft system which is armed only when a hand-held coded transmitter is operated; the system is disarmed upon a subsequent operation of the transmitter. Whenever the transmitter is operated, the horn beeps, and the lights flash; this provides both verification that the system is armed, and serves as a car-locating aid in a parking field. Tampering with the automobile results in intermittent beeping of the horn and flashing of the lights. The horn beeping may be disabled during the verification and car locating sequences, while still operating if unauthorized access to the automobile is attempted. Other features include disabling of the horn beeping by momentarily turning on the ignition; beeping of the horn after the system is disarmed and a door is opened by the operator if, during his absence, unauthorized access was attempted; locking and unlocking of the doors with transmitter operation; and detection of unauthorized access attempts by sensing vibrations in the vehicle radio loudspeakers.

Abstract: A lock comprising a laser adapted to emit a beam of light along a given path. A plurality of photo-diodes are electrically connected together and located at spaced apart positions defining a unique pattern. A key having a light reflecting means is adapted to be located in the path of the laser beam. The reflecting means when located in the laser beam path reflects light back to the photo-diodes in the unique pattern to cause the lock to be unlocked. In another embodiment, the photo-diodes are located in an array which is scanned to determine if light is reflected from the reflecting means of the key in a unique pattern.

Abstract: An arrangement for preventing an unauthorized starting of vehicles which includes a data carrier preferably connected to a key provided for mechanical locks of the motor vehicle and with an evaluating circuit triggering a signal if the correct information is introduced into the arrangement. The data carrier contains at least one of unerasable vehicle-related information or erasable arbitrary information. The evaluating circuit includes at least one read/write unit and a comparison unit wherein the total data of the data carrier are examined and which, in addition to the signal triggered if the information was recognized as correct, passes on the vehicle-related information at least partially to a terminal provided for one of external diagnostic systems or a diagnostic system provided in the vehicle.

Abstract: A burglarproofing device for vehicles is provided wherein a key contains two partial codes. Device on the vehicle compares at least one of the two partial codes with a stored code. Coincidence of the codes will unlock a central locking device. A partial code may be changed by the authorized owner, although the vehicle is locked.

Abstract: The opening order of this safety lock causes the following operations to occur successively: application, to the key, of a coded sequence of angular solicitations in both directions, then the free rotation of this key in a given direction. The decoding is ensured electrically by comparing, with a previously memorized reference sequence, the train of electrical pulses generated by two electromechanical transducers actuated, according to the sequence applied to the key, by a cam itself driven by this key.

Abstract: An electronic system is provided for use with motor vehicles, homes, offices, factories, or other applications where it is desired to control access and/or operation. The security system utilizes a coded electronic key, preferably in the form of a card, which is connected to a decoder for identification by composing the key code with a stored code. If the electronic key is properly matched to the decoder, the system is allowed to function without tripping alarms. The system includes monitoring devices, supervising cabling and various access points, such as doors, hoods, etc., which, if breached without the proper card in place, will trip an alarm. The system is deactivated with the proper key and the system includes appropriate delays to allow proper parties to move in and out of the secured vehicle, room, etc.

Abstract: A solid state switching circuit using a capacitive feedback that creates a positive differential. This positive differential overcomes any half-wave operation of the solid state switches caused by lack of symmetry in its gating circuit.

Abstract: A locking device for utility locks having a lock bolt, wherein a key signal transmitter is disposed in a portable housing and a stationary key signal receiver is disposed in the vicinity of the lock bolt and controls the operation of the lock bolt. The transmitter has a coder for generating a predetermined code specific to the locking device, and the receiver has a decoder for decoding the code generated by the coder. The transmitter coder employs a coding format in which a predetermined sequence of at least three pulses, characterized by at least three different pulse widths is transmitted to the receiver and decoded thereat to unlock the utility lock upon decoding of the predetermined sequence.

Abstract: A self-powered receiver including a series resonant circuit tuned to the carrier frequency of a modulated carrier signal. A demodulator for detecting the envelope which switches a switching transistor ON during the mark portions of the modulator carrier signals and switches the switching transistor OFF during the space portions. A parallel resonant circuit is driven by the switching transistor to produce a.c. modulations to be coupled to a full-wave rectifier. The rectified voltage of the rectifier is used to energize an electromagnetic relay.

Abstract: A location transmitting system for use by one or more guards in a security system. Encoders are located at predetermined reporting locations which have no power supplies. Each guard carries a walkie-talkie radio transmitter which he places in a receptacle at the reporting location, energizing the encoder through external terminals in the receptacle which mate with external terminals of the walkie-talkie and its power supply.

Abstract: The present invention relates generally to security systems, and more particularly, to low cost, highly reliable mechanical-electronic locking units. The electronic security devices of the invention physically include a key assembly, a receptacle for the key in a door or other secured device, a receiver for decoding the signal sent from the key, and a novel electromechanical locking-and-unlocking component which is actuated electrically in response to an appropriate signal from the receiver.

Abstract: An electronic lock mechanism in which the odds against picking or unauthorized opening are extremely high, and wherein an electrically operable bolt is connected with the output of an oscillator in the bolt control circuitry that includes a resistance bridge network including regenerative differential electronic switches connected to selectively activate a pair of relays with series connected contacts in accordance with the direction of unbalance of the bridge, and to activate both relays in response to a balanced operative mode of the bridge so that the relay contacts will coact to close a power supply connection to the oscillator. A control key insertable in a mating keyhole is operative to connect the bridge with a voltage source, insert a resistor component into the bridge network of a value to balance the bridge, and also place a resonating capacitor into a tuned circuit of the oscillator and thereby activate the lock bolt to an unlocked position.

Abstract: A magnetically operated digital switch (10) includes an array of magnetically actuated relays (14-24) mounted adjacent a magnetic shield (26) having an array of holes (28-38) therein corresponding to the location of the relays (14-24). The switch assembly is mounted on a nonmagnetic plate so that the relays can be actuated by a small magnet (58) which is positioned adjacent the holes in the magnetic shield (26). The shield (26) prevents magnetic flux which is applied to one of the relays from being spilled over and inadvertently actuating a nearby relay. An alarm circuit (50) is provided to decode the key number sequence entered into the digital switch (10) for operation of an alarm relay (56) when the proper key number is entered.

Abstract: In order to determine the identity and authorization of a key which is inserted into a cylinder lock, the key is provided with an information carrier with elements which are magnetically passive and inductively readable and yield permanently stored information. The carrier is fixed to the key blade. A reading head mounted in the lock reads the carrier as the key is moved into or out of the lock. An electronic evaluation circuit uses a micro-processor to interpret the information. The carrier is so designed that alterations made in it after it is coded are immediately detected by the evaluation circuit. A particular relationship of the reading head to the information carrier is described for a particular pattern of loop-shaped information elements on the carrier.

Abstract: A security system uses one electronic key that contains many key codes of the user to control several different security devices. Each security device responds to a particular key code or to more than one key code in a master lock system. The key when energized presents its entire repertoire of key codes to the security device and when the security device senses its corresponding code, access is gained. The key may or may not be electrically active. The key may also include mechanical as well as electronic access control. Each security device contains a stored code and electronically correlates the stored code and input pulse patterns of the key codes. A large number of key codes are possible without compromise of system security.

Abstract: A safety interlock system for automotive vehicles and like devices which have an electrically operable component forming part of the engine of said vehicle or like device. The safety interlock system comprises a plurality of latches in the form of integrated circuits which can only be operated in preestablished sequence with a preestablished code of indicia. When the latches are opened pursuant to the preestablished code with inputs in proper sequence from a plurality of manually operable input switches, the interlock system will be enabled, thereby permitting operation of the electrically operable component and hence said engine. Suitable forms of system time delays and system override devices are provided to enable operation of said engine by others for preestablished time delay periods and under controlled delay conditions.

Abstract: An electrically actuated lock for a door or similar access means in which a multiple number of data bits are introduced in a given sequential manner into a plurality of series-connected data transfer parts each operable one at a time and in a selected sequence to finally cause the actuation and withdrawal of the latching mechanism for the lock.

Abstract: A door lock security system is disclosed in which each lock in a multiple lock system is modified by the addition of door lock security apparatus which, in electrical form, stores at least an individual key combination (and possibly several different levels of master key combinations) for the lock. Also, the conventional lock cylinder is replaced with a cylinder assembly which senses the magnetic reluctance state (high or low) of predetermined locations on a key substantially resembling a conventional cylinder lock key in size, weight and general shape and capable of mechanically operating the lock. The magnetic reluctance states of the predetermined locations digitally encode the key combination and the thus encoded combination is compared to the electrically stored one, disabling the mechanical operation of the lock unless the two combinations are identical.

Abstract: An electronic key and lock system. The key unit is plugged in the unit and electrically interconnected therewith only through the leads. Each unit is fitted with a contact strip matrix provided with slots which allow access to the points of intersection of the contact strips from the external face of the unit, the user being provided with conductor pins that can be inserted in the slots so as to set up different combinations. Each unit contains electronic circuits designed to generate (in the case of both the key and the lock) and to detect (in the case of the lock only) a signal in which at least one parameter varies as a function of the established combination, the lock incorporating an electrical power supply for the electronic circuits of both units.

Abstract: An electronic lock having two normally open electrical contacts as input means, the closing and reopening of said contacts sequentially resulting in the entry of a binary code into a shift register. When the contents of the shift register match a predetermined but resettable programmed code, an integrating one-shot delay is triggered and a relay activated after the delay to open the lock. Momentary or continuous operation may also be programmed and reset for the lock. A power reset function is included to clear the shift register when initial power is applied or in the event of a power failure. The input means may be activated by a single three position, spring return switch or two push buttons.

Abstract: A plurality of push-button switches are located on a locking structure which also includes an encoding circuit having a specific code set therein requiring operation of the push-buttons in a predetermined sequence. Operation of the first coded button starts an energy timing circuit which provides electrical energy required to permit the lock to open, the energy timing circuit de-energizing the mechanism after a predetermined time so that the electronic decoding circuit automatically blocks the lock unless the proper code was entered within the predetermined time interval, and the appropriate first push-button, providing for energization of the entire system, was first operated. The timing circuit preferably is a capacitor which is charged upon operation of the first push-button, encoded to be first operated and which, if the proper code is punched, provides energy to a solenoid coil which releases a locking element if the proper code permits discharge of the capacitor through the solenoid.

Abstract: An anti-theft ignition system including a generally tamper-proof canister or housing substantially covering the solenoid of the starter motor with a portion thereof covering the ignition switch terminal of the solenoid. The housing includes a compartment for receiving electronic circuitry including an encoded circuit coupled to or forming a part of a microcomputer operable in response to proper sequential actuation of the ignition key for energizing a silicon controlled rectifier in series relation with the ignition switch.

Abstract: An electronic lock system including a key coder, a key or set of keys and a lock or set of locks. The key coder provides an operator-selectable key code having a new code portion and current code portion to each key. The key receives the selected key code from the key coder and retains it for use with the lock or set of locks, one at a time. When the lock receives the key code from the key, a comparison is made in the lock between the current code portion of the key code and a lock code contained within a memory in the lock. If the current code portion of the key code compares the lock code, the lock is actuated and the lock code in the memory is replaced by the new code portion of the key code. If the new code portion of the key code is identical to the current code portion of the key code, the key will actuate the lock and will continue to do so until the lock is once actuated by a key having a different new code portion of the key code.

Abstract: A keyless system especially useful in controlling the doors and trunk of an automobile is disclosed. The overall system usually comprises an input station containing a keyboard, a signal processor, signal amplification means and an electromechanical grouping which converts the electrical output from the amplifier to mechanical movement in control of a lock. The system is activated by a touch control at the input keyboard and with the power section of the system energized, the lock is controlled in response to a proper sequence of digital input signals created by the operator. The input at the control station is described in terms of a keyboard having five selectors and resulting in approximately three thousand possible combinations for the base code. The signal processor responds to correct combinations of digital inputs with a drive signal.

Abstract: A keyless entry system for an automotive vehicle permits a plurality of operations to be achieved from outside the vehicle by one who is knowledgeable of predetermined digital codes. Functions such as unlocking the doors of the vehicle, opening the rear deck lid, opening a roof window, lowering the windows or programming the system with a user preferred digital access code are all performed by proper sequential operation of a digital keyboard mounted on the outside of the vehicle.

Abstract: The present invention electronic locking device wherein a plurality of thyristors are connected in series, and key type switches whose number is equal to that of the thyristors are provided to self maintain and energize each of the thyristors. An optional set of key type switches is provided to release the self maintained and energized state of the thyristors. A resistor is provided to limit the electric power to be supplied to the gate of each thyristor. Thus a circuit which is capable of supplying a forward base bias to a transistor from the final stage of the thyristors only when the thyristors are sequentially self maintained and energized from the power source side is formed. The load, such as relays or solenoids, which is connected to the collector side of the transistor can be optionally operated by the supply of a forward bias base.

Abstract: A safety interlock system for automotive vehicles and like devices which have an electrically-operable component forming part of the engine of said vehicle or like device. The safety interlock system comprises a plurality latches in the form of integrated circuits which can only be operated in pre-established sequence with a pre-established code of indicia. When the latches are opened pursuant to the pre-established code with inputs in proper sequence from a plurality of manually operable input switches, the interlock system will be enabled thereby permitting operation of the electrically operable component and hence said engine. Suitable forms of time delays are provided to enable operation of said engine by others for pre-established time delay periods and controlled delay conditions.

Abstract: A theft prevention starter system for a motorized vehicle is disclosed which operates to thwart unauthorized attempts at starting the vehicle's engine. The system includes a starter circuit having a starter switch, a bridge circuit, and an anti-theft switch disposed in series with each other. A key is provided having a pair of resistors mounted thereon that are connected to other resistors when the key is inserted into the vehicle's starter lockswitch to form the bridge circuit. A sensing branch of the bridge circuit is coupled to the anti-theft switch and in the event current flows through the sensing branch, the anti-theft switch will be opened to prevent the activation of the starter motor. Current flow in the sensing branch circuit will be absent if resistors having the proper value of resistance are matched when the key is inserted in the lockswitch.

Abstract: An encoding circuit is provided permitting energization of an electromagnetic unlocking solenoid if a series of push-button switches is operated in accordance with a predetermined code. The circuit includes a memory which stores the sequence of operation of the push-buttons in accordance with the code in form of a binary code word. A comparison or decision stage is connected to the memory, typically a shift register, and connected to the memory position of all the digits of the code associated with the specific lock of a binary 1 value, as well as all the digits of the code in a binary 0 value, the decision circuit controlling the unlocking solenoid only if both the binary 1 and binary 0 values stored in the memory upon sequential push-button operation conform to the code associated with the lock, and, simultaneously, a timing circuit energized upon initiation of the first properly coded push-button still provides a timing energization signal, or operating energy to the circuit.