US 3168737 A
Description (OCR text may contain errors)
Feb. 2, 1965 R. WEINSTEIN 3,168,737
RADIO CONTROLLED LOCK Filed Nov. 7, 1962 FIG. /Z ffl (APAC/TY p0 Nae 000,2 G TEA/VS''F/VEE 40c! j eaqzzme F/GZ X; W 23 54 12/613 Z? Z j w I IN VE N TOR 80/420 MV/VSTZ/A/ United States Patent 3,168,737 RADIO CONTROLLED LOCK Richard Weinstein, Huntington, N.Y., assignor, by mesne assignments, to Commercial Factors, Ltd, Montreal, Quebec, Canada Filed Nov. 7, 1962, Ser. No. 235,932 8 Claims. (Ql. 343-225) This invention relates to an electronic means for operating a mechanical transducer at a distance. It has specific application for the operation of a lock whereby access may be obtained without the use of a key or without the manipulation of a combination lock.
Prior art locks have either been operated by keys or by locks which required the use of a combination to set a series of tumblers so that a lock bolt can be withdrawn. The first type of lock not only requires the possession of the key but the operator must insert it into a key hole before the lock can be opened. The combination lock requires the knowledge of the combination and the manipulation of a dial or other arrangement of controls which may take considerable time. The present invention requires the use of a small electronic circuit which can be kept in the pocket, a briefcase, or a ladys handbag. It is not necessary to remove this circuit from the pocket in order to open the door. The operator with the circuit walks up to the door, puts his hand on the knob, and the door is opened immediately, thereby saving considerable time and omitting the necessity for removing the circuit from the pocket.
One of the objects of this invention is to provide an improved electronic lock which avoids one or more of the disadvantages and limitations of prior art arrangements.
Another object of the invention is to provide a lock which is secure against unauthorized entry but can be opened without the use of a key or the manipulation of a combination lock.
Another object of the invention is to increase the speed of response of a signal-operated control means.
Another object of the invention is to operate a signalcontrol mechanism without the use of a portable power unit.
Another object of the invention is to reduce the size of the control circuit so that it may be carried in the pocket of a coat or in a ladys handbag.
The invention comprises a power transceiver which may be activated by a capacity-sensitive oscillator circuit connected to the door knob. The transceiver broadcasts radio waves at two frequencies and receives radio waves at a combination modulated frequency. The arrangement is such that the transmitter and receiver circuits are activated in sequence so that the waves sent out by the combination of oscillator circuits cannot be received directly by a third circuit. The portable circuit carried by the operator is a high Q reflectorwhich receives the radio power from two oscillator circuits and reflects this power at the same frequencies after the oscillators have stopped their power broadcasts. The reflected waves operate the receiver circuit and open the door lock. One feature of the invention includes a free running multivibrator which transfers operating power from the oscillators to the receiver in a sequential manner.
For a better understanding of the present invention, together with other and further objects thereof, reference is made to the following description taken in connection with the accompanying drawings.
FIG. 1 is a schematic diagram of the complete system showing the various circuit components in block form.
FIG. 2 is a capacity switch circuit connected between a door knob and a relay.
FIG. 3 is a schematic diagram showing one form of door lock which may be used with the system.
FIG. 4 is a schematic diagram of connections showing the transceiver which includes two oscillator circuits and a receiver circuit, each activated by a multivibrator.
FIG. 5 is a diagram of connections showing the reflector circuits carried by the operator.
FIG. 6 is a series of graphs showing some of the currents and voltages present in the operating system.
Referring now to FIG. 1, the system includes a power transceiver 111 which may be controlled for its operation by a capacity switch 11 controlled by a door knob 12. The capacity switch circuit is not necessary but it is convenient for the operation of the system since it saves power and insures that the door will not be opened until the operator is in a position to operate the door. The receiver portion of the power transceiver operates a door lock 15 only when a portable reflector circuit 14 is brought within an operating distance of the transceiver circuit 10.
The capacity switch circuit is shown in detail in FIG. 2 and includes a vacuum tube 15 with its cathode and control electrode connected to a resonant concentric line 16. The anode-cathode circuit of triode 15 includes a relay having a winding 17 and a pair of contacts 18, and a source of potential 29. Because of the resonant circuit 16, there is sufiicient feed-back toproduce oscillation at a high frequency. Under the conditions of oscillation, the current through the anode circuit is reduced and contacts 18 remain in their open condition. Now, if a large conductor such as the human body is connected to the outer end of the concentric line (door knob 21) the resonant feedback is altered and the circuit will stop oscillating, thereby increasing the current through the relay winding and closing contacts 18 to apply the potential of source 20 to the output terminal 22. This circuit may be replaced by many other types of circuits such as, a push button, a lever, or any other type of circuit arrangement which can be employed to close a pair of contacts in the permanent installation and thereby activate other parts of the circuit.
The door lock circuit is shown in FIG. 3 and includes an input terminal 23, a rectifying means 24, and some form of an amplifier element 25 which may be either a transistor or a vacuum tube. The output circuit of the transistor 25 includes a power supply terminal 26 and a resonant circuit 27. The resonant circuit may be connected in a number of ways, the one shown in FIG. 3 includes a capacitor 28 and an inductive winding 29 which may be the primary winding of a transformer 31. having a secondary winding 31 which is connected directly to a solenoid 32 which operates the door bolt 33. When modulated radio waves are received by this circuit the rectifier element 24 rectifies them and the capacitor 34 removes the radio frequency components. Transistor amplifier 25 amplifies the resultant current pulses and applies them to the resonant circuit 27. If the modulation frequency corresponds to the resonant frequency of circuit 27, power is transmitted through transformer 30 to operate the sole noid 32 and withdraw the bolt to open the door. Terminal 26 is connected to terminal 22 for receiving power from source 20.
The transceiver circuit is shown in FIG. 4 and includes a free running multivibrator circuit 35 having transistors 36 and 37 arranged with the usual circuit components and receiving direct current power from terminal 38 g which is connected to terminal 22 of the capacity switch circuit; The multivibrator circuit is well known in the art and has been described in prior publications. When this circuit oscillates, the potentials on the transistor collectors are sequentially raised and lowered at the frequency of the multivibrator operating frequency. It should be noted that while the potential is always high on one of the supply conductors 40 or 41, it is never high on both of them at the same time. This switching of operating potentials is illustrated in FIG. 6 where the square-topped waves 42 are applied to conductor 40 and square topped waves as are applied to conductor 41.
Conductor 40 is connected to the collector electrodes of both transistors 44 and 45, each arranged for oscillation at a high radio frequency. Radio frequency chokes 46 and 47 are connected in series with these supply conductors to block the generated radio frequencies from mixing with the multivibrator circuit pulses. A resonant circuit, including a capacitor 48 and an inductor 56, is connected between the base and emitter of transistor-44, thereby providing a feed-back circuit (with capacitor 48A) which produces oscillation at a first radio frequency. The waves generated by this circuit and broadcast into space areshown in FIG. 6 as wavesSl. The second os cillating circuit, containing transistor 45, is similar 'to the first circuit except that its resonant circuit, including capacitor 52 and inductor 53, is tuned to a second radio frequency. The result is two radio frequency waves broadcast for the duration of each of the waves 42. The wave forms from the second oscillator are not shown in FIG. 6 since they are'substantial dupiicates of forms 51. The reflector circuit 14 is shown in detail in FIG. 5. it includes two loop antennas 54 and 55, each wound on a ferrite core and each coupled to a piezoelectric crystal 56 and 57. Other forms of antennas can be used such as folded dipoles. One of the antennas and its crystal 'is tuned to the first radio frequency and the other antenna is tuned to the second frequency. Each of the antennas absorbs power from the broadcast waves, but because of the high Q of. the crystal, the oscillating current (and the mechanical vibrations of the crystal) build up slowly after the start of the train of waves and, for the same reason, decay slowly afterthe end of the wavetrain. This action is illustrated by wave trains 58; in FIG. 6.
Each antenna produces a similar set of wave trains, only one of which is shown in the graph. 7
Because of the high Q of :the crystals 56 and 57, the
, antennas ring or continue to oscillate after the end of wave trains 51. During this time the oscillators are cut oii but a receiver circuit as is activated by one of the square topped waves 43 applied over conductor 41. The receiver circuit includes a transistor 61 and .a tuned loop antenna having an inductor 62 and a capacitor 63, this circuit arranged for receiving both of the waves from antennas 54 and 55. The collector of transistor 61 is connected to terminal 64 which is connected to input terminal 23 of the door lock circuit. Since the frequencies of the waves from the two antennas diiier, the sum of the received currents produces a variable power train, the frequency of the power variations being equal to the difference between the first and second broadcast frequencies. This series of wave trains is shown at 65 in FIG. 6. i r
The door lock amplifier circuit (FIG; 3) is a part of the receiver circuit and includes a rectifier 24 and a'filtering capacitor'iid. These elements rectify the wave trains and eliminate the radio frequency components, thereby producing a series of pulses 66 (see FIG. 6) having a frequency equal to the diiierences in frequency of the two broadcast waves. This series of pulses is applied to the resonant circuit 28, 29, in the collector circuit of transistor 25 (FIG. 3) which is adjusted for resonance at the pulse frequency and the solenoid 32 is activated to withdraw bolt 33. v
From the above description itwill be evident that the door lock can be opened only by the application of two radio waves, each having a frequency whichvcan be re ceived by resonant circuit 62, 63, and having a dilierence l 4 V frequency which causes resonance in circuit 28, 29. Such a lock cannot be opened by an adjustable portable signal generator. Access is possible only when the reflector 14 is available or when two frequencies are known.
Having thus fully described the invention, what is claimed as new and desired to be secured by Letters Patent of the United States is:
l. A radio control system for operating a distant electrornechanical transducer comprising a power transceiver circuit including; a first transmitter circuit for generating and broadcasting alternatingcurrent power at a first frequency and a second transmitter circuit for generating and broadcasting alternating current power at a second frequency; a portable double reflector in close proximity to said transmitter circuits for receiving saidpowerduring a broadcast time interval and for re-radiating a portion of the power after the end of the time interval; a radio receiver in said transceiver" for receiving said reradiated power after the end of the time interval; said radio receiver including a first broadly tuned circuit for receiving both the first and second of said frequencies from the double reflector, an amplifying means, a rectifier connected to the broadly tuned circuit for rectifying the received waves, a second tuned circuit connected to the rectifier responsive to current pulses having a frequency equal to the dificrence between said first and second frequencies, and a coupling means connected to the rectifier for applying said current pulses to said transducer; a source of operating power, switching means for alternately switching said source of operating power to said transmitter circuitsjduring the broadcast timeintervals and for switching said power source to the radio receiver at the end of each of said time intervals and means for initiating operation of saidswitching means at essentially the same time as said double reflector is brought in close proximity to said transmitter circuit.
2. A radio control systemvas claimed in claim 1 wherein said transceivercircuit is connected to said power source by means of a pair of relay contacts.
3. A radio control system as claimed'in claim 1 wherein said transceiver circuit is connected to said power source by means of a capacity switch circuit which includes a resonant line, an amplifier component, and a relay, said resonant line, amplifier component, and relay being connected in series. 7 i q 4. A radio control system as claimed-in clairnzl wherein both of said transmitter circuits include a'resonant circuit for determining the operating frequency, said resonant circuits each including an inductor and a capacitor.
5. A radio control system as claimed in claim 1 wherein said portable double reflector inc ludes two passive antenna's, each tuned to receive the waves broadcast' from one of said transmitter circuits. o
6. A radio control system as claimed in claim 5 wherein said antennas each include a piezoelectric coupling component. I
7. A radio control system as claimed in claim 1 where, in said switching means includes a free-running multivibrator circuit.
8. A radio control system as claimed in claim 7 wherein said multivibrator circuit includes two transistors with the collector electrode of each connected respectively to a conductor which supplies operating power to the receiving circuit-and'to the transmitter circuits.
NEIL C. READ, Primary Examiner.