US3845362A

US3845362A - Electronic lock

Info

Publication number: US3845362A
Application number: US00390162A
Authority: US
Inventors: B Roe
Original assignee: Individual
Current assignee: Individual
Priority date: 1973-08-20
Filing date: 1973-08-20
Publication date: 1974-10-29
Anticipated expiration: 1991-10-29

Abstract

A key operated electronic lock is disclosed. A serial stream of bits representing coded information is generated when a coded key having a plurality of apertures is moved between a light source and a pair of phototransistors. The serial stream of bits is stored in a shift register, and decoded by means of a decoder circuit which operates a locking solenoid.

Description

United States Patent 1191 1 3,845,362 Roe 1 Oct. 29, I974 1 ELECTRONIC LOCK [76] Inventor: Bruce C. Roe, PO. Box 253, 'l' Drummer-J Mlner Aurora "L 60540 AS81810!!! ExammerHarry E. Moose, Jr.

Attorney, Agent, or FirmPeter Vtsserman [22] Filed: Aug. 20, 1973 21 Appl. No: 390,162

[58] Field of Search... 317/134; 340/149 A, 164 R, 340/63, 64; 307/10 AT; 250/555, 556, 568, 569; 70/277, 278, DIG. 51

[57] ABSTRACT A key operated electronic lock is disclosed. A serial stream of bits representing coded information is generated when a coded key having a plurality of apertures is moved between a light source and a pair of phototransistors. The serial stream of bits is stored in a shift register, and decoded by means of a decoder circuit which operates a locking solenoid.

[56] References Cited UNITED STATES PATENTS 7 Claims, 4 Drawing Figures 3,688,269 8/1972 Miller ..340/149A 101 104 1mm 5mm :102 M510 1 if SHIFT rmsrg/e Q0 I 131 m -m R 112 1/ .7 I A 114 a l m5 103 y f ag f, 116 E c I31 134 100 3 1 111 113 s R l a 141 our -SLOPE c 1 o l 132 I10 TRIGGER L l 0- 1 1 132 15a 1 l T nrsrr 01mm 5 R- l D L l 1 l l 1 4 l l I i ll 6 c l s STAGER l 1 9 i l O L 1 PAIENIEII on! 29 m4 J u o m $25 w} u u o m a q r L n N o N 111 m} :35 M W N E5 7 2 5 E983 H 0 Q H was? we: I. r is $53 w E 3 ESQ 3 o o I m w @2 $2? q 3. m2 m3 r k 1 v: n m Q N L E E 2&3 a E t v, 5 2 =23 3% g 5 N2 ELECTRONIC LOCK BACKGROUND OF THE INVENTION l. Field of the Invention The invention relates to an electronic lock and more particularly to an electronic lock operated in response to a predetermined code stored in a shift register and generated by sliding a multiaperatured coded key between a source of light energy and a photosensitive device.

2. Prior Art Prior art electronic locks operable by means of a coded key are known. In some prior art locks a coded key operates a plurality of electrical switches in parallel. Other prior art locks are known which employ a coded card read by mechanical means to activate a number ofswitches. In U.S. Pat. No. 3.749.930 an electronically operated switch is disclosed having a plurality of photocells. one for each possible notch ofa coded key. which are exposed to a light source when the key has been properly inserted in the key slot.

Such prior art locks all have the disadvantage that the key reading unit must have as many switches as there are code positions on the coded key or card. It is known to be desirable in electronic locks to use a key having a large number of code positions in order to enhance the value of the lock. In the prior art arrangements. an increased number of codes has resulted in an increase in the size of the switch and an increase in the number of wires from the switch to the locking device;

SUMMARY OF THE INVENTION In accordance with the present invention. a coded key is read when the key is moved by sliding motion between a source of light energy and a pair of photosensitive devices. The key in accordance with the invention has two sets of aligned apertures. and the photosensitive devices are intermittently exposed to energy from the source generating a serial stream of pulses when the key is inserted into the key slot. The pulses generated by one of the photosensitive devices are applied to the input terminals of a shift register. while the pulses generated by the other photosensitive device are employed to advance the shift register. In this manner a serial stream of pulses generated by the insertion of the key into the key slot is stored in a multistage shift register. A decoder circuit reads the contents of the register in parallel and operates a locking solenoid when a predetermined code has been stored in the shift register. In accordance with the present invention. a coded key may have any number ofcoded positions. but only two photosensitive devices will be required at the key reading position and only two conductors are required from the key reading position to the shift register and decoder circuit. which may be located immediately adjacent the locking solenoid. In an automobile the locking solenoid may be located at the starter motor and the decoding circuit may be made an integral part of the starter assembly.

In one illustrative embodiment of the invention. the coded key has a plurality of evenly spaced rectangular openings aligned longitudinally approximately along the center line axis of the key. and a plurality of slots are cut in one edge of the key. The openings along the axis of the key are employed to generate shift register advance pulses. The slots in the edge of the key contain the code and are used to generate coded data pulses which are gated into the shift register. the presence of a slot representing a logical l, and the absence of a slot representing a logical The slots in the key are so arranged that the center of each slot is substantially aligned with one edge of one of the rectangular openings. Electronic circuitry is employed which detects the change from absence of a signal to presence of a signal and vice versa and each time a rectangular opening passes the light source. a photo-transistor aligned with the rectangular holes generates a single pulse and the electronical circuit generates two shift pulses. If a slot is present in alignment with the edge of a rectangular hole. a data signal will be generated by a phototransistor aligned with the edge of the key and will be gated into the shift register by a shift pulse which also shifts the contents of the first stage of the register to subsequent stages. In this manner a logical I is gated into the shift register for each slot present in the edge of the key and a logical 0" is gated into the shift register for each code position of the key in which no slot exists.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is a schematic of an electrical circuit of an il lustrative embodiment of the invention.

FIG. 2 shows an illustrative coded key and a sectional view of a receptacle into which the coded key may be inserted.

FIG. 3 shows an enlargement of a portion of the illustrative key.

FIG. 4 is a timing diagram showing approximate wave forms of signals occurring at indicated points of the circuit of FIG. I.

DETAILED DESCRIPTION FIG. 1 is a circuit schematic of the electrical circuit of the illustrative embodiment. When a coded key such as key 200 shown in FIG. 2 is inserted in the key receptacle I00 the flow of light energy from the light source I01 to the light sensitive photo-transistors I02 and I03 is blocked intermittently causing the photo-transistors to generate pulsed output signals. The openings I04 of the key receptacle provide a path for the passage of light from the source to the photo-transistor I02 and are aligned just below the upper edge of the key 200 when the key is positioned in the receptacle. A positive signal is generated on the data signal line I06 when one of the slots 201 is in alignment with the holes I04, while no signal is produced on the line I06 when the flow of light energy to photo-transistor I02 is blocked by any portion of the key. The signal line I06 is connected to one input terminal of the first stage of the shift register "0 and to an inverter gate 107. The output signal line I08 of inverter gate I07 is connected to another input terminal of the first gage of shift register I10.

When the key is positioned in the receptacle the line along which apertures are aligned will be in alignment with the holes I05. A positive signal is generated on the clock signal line 110 when one of the apertures 202 is in alignment with holes and no signal is generated on the clock signal line when the flow of light energy to photo-transistor 103 is blocked by any portion of the key 200. The transition from absence of a signal to presence of a signal on the clock signal line 110 is relatively slow since the key 200 is moved into the key receptacle manually which is necessarily slow in comparison with the reaction time of the electronic circuitry. In order to avoid the generation of extraneous clock pulses during transition. an operational amplifier II] is employed with a feedback resistor 2 having a value R2 which may be chosen to be twice as great as the value R] of the input resistor 113. Choosing the values of the two resistors in this manner the operational amplifier I l I will have an effective hysteresis characteristic, which under most circumstances will as sure a single pulse at the output of the operational amplifier lll as a slowly varying signal occurs on the clock signal line ll0. Operational amplifiers connected into a circuit in the manner shown in FIG. I are well known in the art and need no further elaboration.

The circuit of FIG. I incorporates a positive slope trigger H4 and a negative slope trigger H5. The positive slope trigger ll4 generates a relatively short duration positive output pulse in response to a change at its input terminal from an existing voltage level to a higher voltage level. The negative slope trigger 115 generates a relatively short duration positive output pulse when the signal at its input changes from an existing voltage level to a lower voltage level. The output pulse of the trigger circuits may be adjusted to have a duration of approximately I milli second. Trigger circuits such as circuits I14 and US are well known in the art and no specific description of these circuits is required. The output terminals of the slope trigger circuits 4 and IIS are connected to an OR gate 116 which generates an output signal when a signal is applied to either of its input terminals. The output terminal of the OR gate is connected to the shift input connection of the shift register I20. which receives a shift pulse each time a transition occurs on clock signal line 110.

The timing diagram of FIG. 4 shows approximate wave forms of signals occurring at indicated points of the circuit of FIG. I. The wave form A of FIG. 4 corresponds to the output of the operational amplifier l1] and is generated when the apertures 202 of key 200 are moved past the holes I thereby interrupting the flow of light energy from the source I01 to the phototransistor 103. The leading edge 40] of the wave form occurring at point A in the circuit is generated when the forward edge of one of the apertures. for example the edge is moved in front of holes 105 ofthe key receptacle I00. The trailing edge 402 of the wave form occurring at point A will be generated when the rearward edge of one of the apertures such as edge 302 is moved past the holes I05 in the key receptacle 100. As indicated above. the positive slope trigger ll4 generates a relatively short duration pulse when a transition at its input terminal occurs front an established voltage level to a relatively higher voltage level as. for example. the transition of leading edge The wave form which occurs at the output terminal of the positive slope trigger IN is identified by the letter Bin FIG. 4. Similarly. the negative slope trigger ll5 generates an output pulse when the signal at its input terminal makes a transition to a relatively lower voltage level. such as the transition of trailing edge 402. The wave form occurring at the output of the negative slope trigger I15 is identified by the letter C in FIG. 4. The OR gate 116 generates an output signal whenever a signal occurs on either of its input terminal. which is used to shift data into the shift register and to advance the data from the first stage of the shift register to subsequent stages.

Thus. as can be seen a shift pulse is generated first when the forward edge of one of the apertures 202 of key 200 is moved past the holes I05 and another shift pulse is generated when the rearward edge of the aperture is moved past the holes 105. The coded key shown in FIG. 2 has 5 apertures. indicating that a total of 10 shift pulses will be generated as the key is inserted in the key receptacle I00.

As can be seen from the enlarged view of the coded key in FIG. 3, the forward and rearward edge of each aperture 202 is aligned with the approximate center of one of the slots 20! which have been cut in the upper edge of the key. For illustrative purposes the forwardmost 3 apertures of the key have been labeled .r. y. and z and the three pulses x. y, and z in FIG. 4 represent the wave form at point A which is generated when the key 200 is inserted in the key receptacle and the correspondingly labeled apertures are moved past holes 105. Furthermore. the first six places where slots might be cut in the upper edge of the key are indicated by the letters m. n. o, p. q. and r. In the key of this illustrative example slots have been cut in spaces n. p. and q of the first six spaces of the key. The wave form identified by the letter I in FIG. 4 shows that the pulses n. p. and q will occur when the coded key 200 is inserted in the key receptacle I00 and the correspondingly labeled slots are moved past holes 104. For a different coded configuration, pulses m, u. and r could occur.

As can be seen from FIG. 4, a shift pulse is generated at the point S in the circuit in coincidence with each possible pulse at point I in the circuit. The shift register I20 may be any well-known shift register in which data is advanced by means ofa series of shift pulses. The signal occurring at the point I and the inverse thereof are applied to the input terminals of the first stage of the shift register. It will be understood that the equivalent of a logical 1" will be gated into the first stage of the shift register if a positive signal is present at the point I when the shift pulse occurs and that the equivalent of logical "0 will be gated into the first stage of the shift register ifthere is no positive signal at point I when the shift pulse occurs.

The shift register I20 comprises a plurality of shift register stages. As mentioned. the illustrative key 200 has five apertures 202 and can have as many as ten code slots 20] cut along the upper edge of the key. A shift register stage is provided for each possible slot. Each shift register stage has a pair of input terminals. a shift terminal. a pair of output terminals and a reset terminal. The input terminals of the first stage. stage 0 ofthe shift register [20. are connected to the lines I06 and I08. The signal occurring on line 108 is the inverse ofthe signal occurring on the data signal line I06, having been inverted by means of the inverter 107. The input terminals of stage 1 through stage 9 of the shift register I20 are connected to the output terminals of the preceding register stage. One of the output terminals of each of the shift register stages is connected to a decoder circuit I30 which comprises a plurality of inverters l3l. The input terminals of the coder circuit may be connected directly to an output AND gate I34 or may be inverted through an appropriate inverter circuit 13]. by the selective connection of the jumper wires 132.

The code cut into the illustrative key 200 by means of the slots 20] comprises a l0-bit code and as can be seen the code can be represented in terms of ls and Os as follows:

As will be understood with reference to the drawing. when the above-noted code is inserted in the shift register 120, the first and last stages of the shift register will contain a 0" and the second stage of the shift register will contain a I." Since the output signal from the first and last stages of the shift register are inverted by inverter gates 13], and the output signal from the second stage of the shift register is not inverted. the corresponding input terminals of the AND gate 134 will be presented with a signal equivalent to a logical 1." Similarly, by selectively connecting the jumper wires 132 in the decoder circuit 130 all input terminals of AND gate 134 will be presented with a logical 1" if the above-noted code is inserted in the shift register I20. Clearly any other -bit code can be devised which through proper connection of the jumper wires will cause all input terminals of the AND gate 134 to be presented with a logical The coil of a locking solenoid 141 is energized by means of a signal generated by AND gate 134 when a predetermined code. appears in the shift register 120. The locking solenoid may. of course; be used to perform any number of functions, such as allowing the en gagement of a starter in an automobile or the flow of current to the ignition circuit. or to perform numerous other locking functions.

When the key is removed from the key receptacle 100 the shift register is reset by a pulse applied to reset terminal R of each of the stages of the shift register. The reset pulse is generated by means of the reset circuit [50 which generates a short duration output pulse when the photo-transistor 103 is continually exposed to the light source 101 for greater than a predetermined period oftime which substantially exceeds the duration of the pulses A. shown in FIG. 4; generated by the insertion ofthe key into receptacle 100. The reset circuit 150 may comprise a capacitor timing circuit having a relatively long time constant and a one-shot multivibrator to generate a single reset pulse after the key has been removed from the receptacle.

lt will be understood that the above is the description of an illustrative embodiment of applicants invention and it is recognized that numerous other arrangements may be devised by those skilled in the art without departing from the basic principles of the invention.

What is claimed is:

1. An electronic locking arrangement comprising:

a source of light energy;

a first and a second sensor responsive to intermittent exposure to light energy from said source to generate a plurality of multi-state signals;

a coded key having a first and a second set of aligned apertures;

a key guide for guiding said key in a path between said source and said sensors wherein said first set of apertures are aligned along a line intersecting a line extending from said source to said first sensor and said second set of apertures are aligned along a line intersecting a line extending from said source to said second sensor. whereby said sensors are intermittently exposed to light energy from said source when said key is slidingly inserted into said guide;

said apertures of said first set each having a substan tially rectangular shape and having a forward edge and a rearward edge. the center of each of said ap ertures of said second set being approximately aligned with one of said forward or one of said rearward edges;

a multi-state shift register;

means for connecting said sensors to said shift register. said shift register being responsive to signals from said first sensor to store the states of signals generated by said second sensor in said shift register; and

means connected to said shift register for selectively operating a locking solenoid.

2. An electronic locking arrangement in accordance with claim 1, wherein said means for connecting said first sensor to said shift register comprises first pulse generating means responsive to the transition from a first state to a second state of a signal from said first sensor to generate a first output pulse and second pulse generating means responsive to the transition from said second to said first state of a signal from said first sensor to generate a second output pulse and means responsive to said first and second output pulses to generate a shift register advance pulses.

3. An electronic locking arrangement in accordance with claim 2, and further comprising a signal amplification circuit having signal feedback connected between said first sensor and said first and said second pulse generating means. and having an effective hysteresis characteristic.

4. An electronic locking arrangement in accordance with claim 1, and further comprising reset means responsive to a signal from said first sensor of substantially longer duration than signals produced by normal insertion of said key in said guide to generate a reset signal for resetting said shift register.

5. In combination,

a key and an electronic lock having a source of light energy, a pair of light sensitive detectors for generating an output signal when exposed to light energy emitted by said source. and means responsive to signals from said detectors to generate a lock operative signal;

said key having at least one longitudinally extending edge. and a plurality of code slot areas along said edge defining slots which may be cut across said edge and having predetermined spacing between centers of said areas;

a number of substantially rectangular holes in said key aligned along a line parallel to said edge. each of said holes having a first and a second edge extending in a direction transverse to said line; and

the centers of each of said slots being in alignment with the first or the second edge of one of said holes.

6. An electronic key lock comprising:

an energy emitting source;

a first and a second sensing device;

a coded key having a plurality of code apertures aligned along a first line and a plurality of clock apertures aligned along a second line;

a key guide mounted between said source and said devices;

said first line of said key being aligned with said first device and said second line of said key being 7 aligned with said second device. when said key is in said guide;

said first device being responsive to intermittent exposure to said source resulting from sliding motion of said key in said guide to generate a plurality of code pulses corresponding to the code apertures of said key;

said second device being responsive to intermittent exposure to said source resulting from the sliding motion of said key in said guide to generate a plurality of clock pulses corresponding to said clock apertures;

a pulse circuit comprising a signal amplification circuit having an effective hysteresis characteristic, connected to said second sensing device and responsive to said clock pulses to generate shift register advance pulses;

shift register means having a plurality of stages, connected to said first sensing device and said pulse circuit and responsive to said advance pulses to store said code pulses therein; and

means connected to said shift register and responsive to a predetermined code stored therein to generate a lock operate signal.

7. An electronic key lock comprising:

an energy emitting source;

a first and a second sensing device;

a key guide mounted between said source and said devices;

said first line of said key being aligned with said first device. and said second line of said key being aligned with said second device, when said key is in said guide;

said first device being responsive to intermittent exposure to said source resulting from sliding motion of said key in said guide to generate a pluraltiy of code pulses corresponding to the code apertures of said key;

shift register means having a plurality of stages. said shift register being connected to said first and said second sensing devices and responsive to said clock pulses to store said code pulses therein;

shift register reset means comprising a timing circuit and responsive to a signal from said second sensing device of substantially greater duration than signals produced by normal insertion of said key in said guide to generate a reset signal for resetting said shift register means; and

means connected to said shift register means and responsive to a predetermined code stored therein to generate a lock operate signal. l =t

Claims

1. An electronic locking arrangement comprising: a source of light energy; a first and a second sensor responsive to intermittent exposure to light energy from said source to generate a plurality of multi-state signals; a coded key having a first and a second set of aligned apertures; a key guide for guiding said key in a path between said source and said sensors wherein said first set of apertures are aligned along a line intersecting a line extending from said source to said first sensor and said second set of apertures are aligned along a line intersecting a line extending from said source to said second sensor, whereby said sensors are intermittently exposed to light energy from said source when said key is slidingly inserted into said guide; said apertures of said first set each having a substantially rectangular shape and having a forward edge and a rearward edge, the center of each of said apertures of said second set being approximately aligned with one of said forward or one of said rearward edges; a multi-state shift register; means for connecting said sensors to said shift register, said shift register being responsive to signals from said first sensor to store the states of signals generated by said second sensor in said shift register; and means connected to said shift register for selectively operating a locking solenoid.

3. An electronic locking arrangement in accordance with claim 2, and further comprising a signal amplification circuit having signal feedback connected between said first sensor and said first and said second pulse generating means, and having an effective hysteresis characteristic.

5. In combination, a key and an electronic lock having a source of light energy, a pair of liGht sensitive detectors for generating an output signal when exposed to light energy emitted by said source, and means responsive to signals from said detectors to generate a lock operative signal; said key having at least one longitudinally extending edge, and a plurality of code slot areas along said edge defining slots which may be cut across said edge, and having predetermined spacing between centers of said areas; a number of substantially rectangular holes in said key aligned along a line parallel to said edge, each of said holes having a first and a second edge extending in a direction transverse to said line; and the centers of each of said slots being in alignment with the first or the second edge of one of said holes.

6. An electronic key lock comprising: an energy emitting source; a first and a second sensing device; a coded key having a plurality of code apertures aligned along a first line and a plurality of clock apertures aligned along a second line; a key guide mounted between said source and said devices; said first line of said key being aligned with said first device, and said second line of said key being aligned with said second device, when said key is in said guide; said first device being responsive to intermittent exposure to said source resulting from sliding motion of said key in said guide to generate a plurality of code pulses corresponding to the code apertures of said key; said second device being responsive to intermittent exposure to said source resulting from the sliding motion of said key in said guide to generate a plurality of clock pulses corresponding to said clock apertures; a pulse circuit comprising a signal amplification circuit having an effective hysteresis characteristic, connected to said second sensing device and responsive to said clock pulses to generate shift register advance pulses; shift register means having a plurality of stages, connected to said first sensing device and said pulse circuit and responsive to said advance pulses to store said code pulses therein; and means connected to said shift register and responsive to a predetermined code stored therein to generate a lock operate signal.

7. An electronic key lock comprising: an energy emitting source; a first and a second sensing device; a coded key having a plurality of code apertures aligned along a first line and a plurality of clock apertures aligned along a second line; a key guide mounted between said source and said devices; said first line of said key being aligned with said first device, and said second line of said key being aligned with said second device, when said key is in said guide; said first device being responsive to intermittent exposure to said source resulting from sliding motion of said key in said guide to generate a pluraltiy of code pulses corresponding to the code apertures of said key; said second device being responsive to intermittent exposure to said source resulting from the sliding motion of said key in said guide to generate a plurality of clock pulses corresponding to said clock apertures; shift register means having a plurality of stages, said shift register being connected to said first and said second sensing devices and responsive to said clock pulses to store said code pulses therein; shift register reset means comprising a timing circuit and responsive to a signal from said second sensing device of substantially greater duration than signals produced by normal insertion of said key in said guide to generate a reset signal for resetting said shift register means; and means connected to said shift register means and responsive to a predetermined code stored therein to generate a lock operate signal.