US 3459961 A
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Description (OCR text may contain errors)
ssa SR BT14591961 v V, l
R. J. RAVAS MOVEMENT RESPONSIVE LIGHT CONTROL MEA-NS Filed April 17, 1967 'ausm xR- Aug. 5, 1969 United States Patent O Fice U.S. Cl. 307-116 7 Claims ABSTRACT OF THE DISCLOSURE A device for controlling the application of power to a load in response to the movement of an object within a prescribed area. The device comprises transmitter means for generating and radiating a sound wave having a substantially constant carrier frequency, means for receiving the sound wave and for producing an output signal in response thereto, a detector circuit connected to produce an output signal in response to doppler shifts in the frequency of the received sound wave caused by the object movement, a time delay circuit connected to produce a switching voltage in response to the detector circuit output signal, and to remove the switching voltage at a predetermined time after cessation of the movement causing the doppler shifts, and a switching c ircuit connected to apply and remove power to the load in respective response to the production and removal of the switching voltage.
Background of the invention The present invention relates generally to a circuit arrangement adapted to control the application of power to a load in response to the detection of movement within the surveillance area of the arrangement. The invention relates particularly to a sound or sonar light control device adapted to automatically turn on room lights when one or more persons enter the room, and to automatically turn off the lights when the last person leaves the room.
The invention attains two basic objectives, namely, substantial reduction in lighting cost, and the elimination of the need for wall switches and associated wiring in lighting systems. The invention has other advantages as will be explained hereinafter. l
Often in factories and oices, lights are continuously left burning so that if the on time of the lights were reduced only to the 40 hour work week, the reduction would be to a small percentage of the previous power consumption, namely,
40 hours 7 24 hours or 23.8% for a savings of 76.2% in lighting cost. Add to this the savings in lighting costs for areas where lights need not always be on during the normal working hours, and the possible savings realized can go to 90% in lighting cost. The importance of such an economy is readily seen in regard to large industrial and ofiice buildings.
With the development and continual expansion of the portable partition industry, the elimination of wall switches and wiring would effect further considerable savings. Further, such partitions and walls could be manufactured, installed and moved without regard for wall wiring and switch accommodations if automatic light switching devices were employed in say the lighting fixtures.
Brief summary of the invention The present disclosure describes a novel, compact and inexpensive movement sensing device which provides the Considerable cost saving and other advantages in-light systems explained above. The device comprises preferably an 3,459,961 Patented Aug. 5, 1969 ultrasonic frequency oscillator energizing av transmitting device such as ceramic transducer, an ultrasonic frequency sensing receiver, which may be another ceramic transducer, miniature (integrated) tuned amplifying circuits, a detector circuit and time delay circuit, and a solid state power switching circuit.
The transmitter radiates a substantially constant frequency ultrasonic sound wave in the room. The ordinary movement of a person or persons in the room, even though slight, causes a sufficient doppler shift in the frequency of the sound wave that is detected by the detector circuit. The frequency shift is received and amplified (along with the constant carrier frequency) by the receiver and amplifiers, respectively, and applied to the detector which detects the Ifrequency shift by responding to amplitude variations of the amplified waveform. The envelope waveform is amplified and clipped, producing rectangular pulses which are directed to the time delay circuit which causes the circuit to produce a switching voltage capable of gating a switching device'in the power switching circuit. This circuit causes energization of the lamp or lighting load. The light or lights are now lit and remain lit as long as there is motion. When the last person leaves the room, motion ceases therein so` that the doppler shift frequency no longer exists to be detected by the detector. The time delay circuit, absent the detector output pulse,
t functions to remove the switching voltage after a time delay predetermined by the charging time of an integrating capacitor in the circuit.`This delays the immediate turning off of the lights so that if the room is successively frequented the lights will remain on.
By use of integrated circuits and solid state components,
the overall size of the device is such that it can be assembled or installed in a light fixture or otherwise packaged to replace the wall switch thereby updating all existing lighting systems. Installation costs may be eliminated by adapting the novel device for simple plug-in connection for standard wall outlets to control a lamp or other loads connected thereto.
The drawings The above mentioned and other advantages will become more apparent with consideration of the following detailed description taken in connection with the accompanying drawing, in which:
FIGURE l is a block diagram of a movement sensing device constructed in accordance with the principles of the invention; and
FIG. 2 is a diagram of the sensing device of FIG. l in which a portion thereof is shown in schematic circuit detail.
Preferred embodiment Specifically, there is shown in FIG. 1, a block diagram representing the stages of the novel movement sensing device generally designated 10. The stages are commonly supplied with direct current voltages by a power supply 12 connected across an alternating current line.
A sound energy producing .oscillator 14 is connected to energize sound transmitting.or'radiating means 16 with a substantially constant ultrasonic carrier frequency. The transmitting means-maybe a ceramic transducer made from such materials-:as barium titanate, lead zirconate or other suitable substances.
The constant carrier frequency is radiated by the transducer 16 as indicated by lines 1S, and the constant carrier reaches a sound responsive receiving means or microphone 20 as indicated by lines 19. The microphone may be another ceramic transducer identical to the transmitting transducer 16.
The microphone or receiving transducer 20 is connected to a first amplifier circuit 22 tuned to the frequency of the constant carrier transmitted by the transducer 16. A second amplifier circuit 24 is connected to receive the amplified output of the first amplifier, and further arnplifies the frequency of the constant carrier.
The second amplifier 24 is provided with an automatic gain control arrangement for producing a constant level output signal voltage for detection. This allows the sensing device 10 to be used in substantially any size room. The first and second amplifiers are preferably integrated circuits in miniature package form though the invention is not limited thereto since other suitable amplifier circuits may be used.
A detector circuit 26 is connected to receive the output of the second amplifier, and a time delay circuit 28 is, in turn, connected to receive the output of the detector circuit. The time delay circuit is connected to produce a switching voltage for energizing a switching circuit 30 connected to control the application of AC power to a load 32.
In FIG. 2, the sensing device 10 is shown in further circuit detail. Specifically, the power supply 12 is connected across the AC line through a rectifying diode 34 and a voltage dropping resistor 35 on one side of the line, and a diode 36 forming part of a diode bridge 38 on the other side. The anode of the diode 36 is connected to a common connecting line 39.
A direct current voltage regulator circuit 40 is provided in the power supply 12 comprising a transistor 41, a transistor base resistor 42, an emitter resistor 43 and a Zener diode 44 connected between the common line 39 and the base of the transistor.
The detector 26, the delay circuit 28 and a thyristor or SCR firing circuit 46 are connected to the power supply for B+ voltage through a -resistor 47. A by-pass capacitor 45 is connected between the B+ line and the comin-ion line 39.
The power supply 12 further comprises an input filter capacitor 48 connected across the voltage regulator 40, .a second regulated low voltage supply comprising a blocking diode 50, a voltage dropping resistor 51, a filter capacitor 52 and a Zener diode 53. The first and second amplifiers 22 and 24 are supplied with the low voltage DC from this power supply.
The ultrasonic oscillator 14 is shown comprising a transistor 56, a tank circuit consisting of a coil 57 and a capacitor 58 connected in the collector circuit of the transistor, a blocking diode 59 and a grid leak type of arrangement consisting of a resistor 60 and a capacitor 61 in the base circuit of the transistor. The oscillator includes a further a coil 62 connecting the base circuit of the transistor to its emitter via the common connecting line 39, and a resistor 64 connecting B+ supply to the base circuit of the transistor to facilitate oscillator startup. Other suitable oscillator circuits could be used in place of the one disclosed. Across the tank circuit is connected the transducer 16.
The detector circuit 26 includes a transistor 70 with its base connected to the output of the second amplifier and AGC circuit 24 through a coupling capacitor 71 and an RF filter resistor 72. The base and the collector of the transistor are connected together through a by-pass capacitor 73, the base being further connected to the B+ line by a resistor 74, and the collector connected to B+ through a resistor 75. The emitter of the transistor 70 is connected directly to the common connecting line 39 while the collector of the transistor is connected to the common line through a capacitor 76. Other suitable detector circuits may be employed in place of the circuit 26 since the invention is not limited to the one described.
The time delay circuit 28 includes two cascaded transistors 78 and 79 with the base of the transistor 78 connected to the collector (and output) of the detector transistor 70 through a blocking diode 80 and resistor 8l. The base of the transistor 78 is connected to its collector and the collector of the transistor 79 through an integrating capacitor 82. B+ voltage is supplied to the collector through a resistor 83 while the emitter of the transistor 79 is connected directly to the common line 39. Other suitable time delay means may be used in place of the circuit 28.
The switching circuit 30 includes the firing ci-rcuit 46,
a thyristor or cont-rolled rectifying device 85 and the diode bridge 38 connected between the gate and the anode terminals of an AC or symmetrical switching device 86. The input of the firing circuit 46 is connected to the transistor collectors (and output) of the delay circuit 28, and is preferably an integrated circuit in minature package form, for example, the Westinghouse integrated circuit type WC185T described in Amplifier-SCR Firing Circuit Preliminary Specifications published August 1966 though the invention is not limited thereto. Other suitable firing circuits may be employed.
The switching circuit 30 includes further a voltage dropping resistor 88 connecting the output of the firing circuit 46 to the gate terminal of the controlled -rectifier 85, and a resistor 89 connecting the gate terminal to the common line 39.
The symmetrical switch 86 is connected in series with the lamp load 32 across the AC line with diodes 91, 92 and 93 completing the bridge circuit 38.
In operation, power is applied to the diode 34 in the power supply 12, and to the symmetrical switch 86 by a suitable line switch or other means not shown. With no movement in the room under surveillance by the device 10, the symmetrical switch is ungated so that the lamp or light load 32 remains in an off condition. The diode 34 rectifes the alternating current voltage from the line, and the filter capacitor smooths the resulting DC ripple. The Zener diode 44 and the transistor 41 function together to regulate the direct current (B+) voltage with the voltage at the base of the transistor being fixed by the Zener diode so that the transistor circuit functions as an emitter follower circuit. Without the transistor 41 working with the Zener diode 44, the regulator circuit 40 would be a much less efficient regulating means though other regulating means may be used in place thereof or in conjunction therewith.
The oscillator circuit is energized by the regulated B+ voltage with the collector of the transistor 56 connected thereto through the tank coil 57. Base current therefore -is provided through the resistor 64 and the diode 59. The grid leak type arrangement (comprising resistor 60 and capacitor 61) in the base circuit provides current fiow through the coil 62 which develops a low alternating voltage thereacross for the low voltage supply.
The electrical values of the tank resistor 57 and capacitor 58 are chosen to develop a carrier frequency preferably in the ultrasonic range so that, when radiated, it will not -be heard by persons in the room or rooms under surveillance. The sound transmitting or radiating transducer 16 is directly energized by the electrical energy developed in the tank circuit, and converts the electrical energy into ultrasonic energy for radiation. The capacitor 45 by-passes any of the carrier frequency energy in the B+ line to ground.
The low alternating voltage developed across the coil 62 is rectified by the diode 50, and filtered and regulated respectively by the capacitor 52, resistor 51, and the Zener diode 53. This voltage is supplied to the amplifiers 22 and 24 as shown.
With the ultrasonic carrier radiated in a room, and with no movement in the room, the carrier is received by the receiving transducer 20 and converted into elec-I trical energy having the same frequency. The carrier frequency is amplified by the two amplifiers 22 and 24, and the amplified carrier is coupled to the detector circuit 26 by the capacitor 71. With no modulation on the carrier, the carrier is by-passed around the detector transistor by the capacitor 73, which, in combination with the resistor 72, forms an RC circuit having'a time con= stant suitable for such by-pass action.
The capacitor 82 in the delay circuit 28 chargesslowly with a small amount of B-lcurrent flow therethrough and through the base of the transistor 78 and 79 to ground. When the capacitor 82 approaches its maxi-mum level of charge, the transistor current flows approach zero.
The collector of the transistor 70 is held in saturation unless there is some amplitude variation on the carrier signal coupled to the base of the transistor. In that case, collector current pulses are developed and directed to the delay circuit 28 in a manner presently to be explained.
Thus, with no carrier modulation, the signal to the -base of the transistor 70 is minimal so that its output signal is minimal which is insufficient to cause conduction of the diode 80. In a similar manner, no signal is provided to the base of the time delay transistors 78 and 79 (except for the small charging current of the capacitor 82) to cause actuation thereof so that the firing circuit 46 is in a quiescent state with the controlled rectifier 85 and the symmetrical switch 86 remaining ungated. The light load 32, receiving no line current through the ungated symmetrical switch, is off.
When a person enters the room, or with movement in the room, the frequency of the sound carrier in the room is modulated by a doppler shift frequency which is received by the receiving transducer 20 and converted into electrical energy with the carrier. The modulated carrier is amplified by the amplifiers 22 and 24, and applied to the detector circuit 26 by the coupling capacitor 71. The
modulating (doppler shift) frequency is detected by the circuit 26 with the modulation frequency providing a base signal for the transistor 70. The transistor conducts to provide an output voltage capable of triggering the diode 80 which, in turn, provides a train of voltage pulses across the resistor 81 to the base of the transistors 78 and 79 in the delay circuit 28. This causes the transistors to conduct which provides a DC output voltage of a level capable of driving the ring circuit 46. A discharge path is also completed for the capacitor 82 so that the capacitor rapidly and completely discharges, thereby resetting the circuit for purposes presently to be explained. The firing circuit produces a bistable signal which operates to gate the controlled rectifier 85 when the input signal to the firing circuit reaches the prescribed level.
When the controlled rectifier 85 is gated, a DC path is completed through the rectifier to the side of the diode 4bridge circuit 38 opposite the common line 39. On one half cycle swing of the line voltage, gate current for the symmetrical switch flows through the diode 90, the con-s trolled rectifier 85, the diode 92, and the gate to cathode junction of the symmetrical switch 86. O n the reverse cycle, gate current flows through the direct current supply circuit 12, the'comfmon line 39, the diode 92 and the symmetrical switch as one path, and through the diode 91, the controlled rectifier 85 and the diode 36 for a second path.
With gate current provided for the symmetrical switch 86 on both half cyclevswings of the line voltage, the switch conducts for both half cycles thereby energizing the light load 32. The light will remain on as long as there is the slightest motion in the room to cause the doppler shift in the frequency of the carrier within the room.
When the last person leaves the room, or when motion otherwise ceases, the carrier frequency will have no doppler shift modulation to be detected by the detector circuit 26. Consequently, no base signal is provided to the transistors 78 and 79 in the delay circuit 28 from the detector circuit. However, the capacitor 82 functioning as an integrating capacitor now begins to charge with a small B+ current flow therethrough with the signal to the base of the transistor 78 (from the detector) being cut off. Thus, the current ow through the charging can pacitor 82 functions to keep the transistors 78 and 79 in an on condition. B+ current is therefore allowed to ow in the collector circuits of the transistors so that an output voltage is maintained with a switching level sufficient to drive the firing circuit 46 in the switching circuit 30, thereby keeping the light 32 energized with line current fiow through the symmetrical switch 86.
However, as the capacitor 82 approaches its maximum level of charge, the base current of the transistors 78 and 79 approaches zero so that the output voltage required to drive the tiringncircuit 46 is no longer available. The firing circuit now ceases to provide the controlled rectifier with a gate signal which, in turn, opens the gate circuit to the symmetrical switch 86. This opens the load circuit so that the light-32, in the room, goes out.
Thus the time it takes for the capacitor 82 to charge to near its maximum value, is the time it takes for the lights in a room to be turned off after the last motion or movement is detected by the novel sensing device 10. The delay time of the circuit 28 may simply change by changing the value of the integrating capacitor 82 so that any suitable delay can be provided for in turning off the room lights after the last person leaves.
It should now be apparent from the foregoing description that a new and useful motion sensing device has been disclosed. The device is particularly useful yfor detecting the presence of persons within aroom, and for energizing a load, such as room lights, in response thereto. This is accomplished by generating and transmitting a sound energy carrier frequency, and detecting the doppler shift in the carrier frequency caused by the movements (slight or otherwise) of a person or ypersons within the room. A time delay circuit is employed to delay the turning off of the lights after the last movement is detected so that the lights in rooms .frequently visited will remain on.
Extreme savings in lighting costs can be effected with the present invention as described earlier, as well as providing a compact unit suitable for mounting as an ordinary wall switch or in a light fixture. The sensing device 10 may be further fconveniently connected in the power cord of a lamp or other suitable load means.
Though the invention has been describednwith a certain degree of particularity, it should be noted that changes may be made therein without departing from the spirit and scope of the invention. For example, the device 10 may be employed as a burglar alarm in which case the light 32 would be an alarm light or other suitable load device.
I claim as my invention:
1. A device for reducing the consumption of power and thus power costsmby-controlling the application of power to load in response to the movement of an object within a prescribed area, the device comprising:
a transmitter -means for producing a sound wave having a substantially constant frequency,
transducer means for receiving the soundwave and for producing an electrical output signal in response thereto,
a detector circuit connected to produce an output signal in response to a doppler shift in the frequency of the sound wave received by the transducer receiving means caused by the object movement,
a time delay circuit connected to produce a switching voltage in response to the detector circuit output signal, and to remove the switching voltage at a predetermined time after the cessation of movement causing the doppler shift, and
a switching circuit connected to apply and remove power to the load in respective response to the production and removal of the switching voltage.
2. The device of claim 1 in which the transmitter and receiving means include ceramic transducers.
3. The device of claim 1 in which the switching Circuit includes a firing circuit, a controlled rectier connected to be gated by the firing circuit, and a solid state symmetrical switch connected to be gated by the controlled rectifier.
4. The device of claim 1 in which at least one amplifier circuit is connected to amplify the electrical output signal from the receiving means, and
an automatic gain control circuit is connected to provide a signal to the detector circuit having a constant voltage level characteristic.
5. The device of claim 1 in which the transmitter means includes a transistor feedback oscillator for generating an electrical signal in the ultrasonic frequency range, and
a transducer means for converting the electrical signal into sound energy, and for radiating the sound energy at substantially the same frequence as the: electrical signal.
6. The device of claim 1 in which the time delay circuit is an integrator circuit employing at least one transistor having its base connected to the output of the detector circuit through a blocking diode.
7. The device of claim 1 in which at least one amplifier circuit is connected to amplify the electrical output signal of the receiving means, and Y a. ring circuit connected to control the gating of a controlled rectifier in the switching circuit,
the amplifier and firing circuit being integrated circuits in miniature package form.
. References Cited 5 UNITED STATES PATENTS i,
2,788,509 4/ 1957 Bolzmann 315-208 X 2,939,135 5/ 1960 Beckerich et al.,
3,046,519 7/ 1962 Polster.
3,061,758 10/1962 Cobb 315-159 X 10 3,225,265 12/'1965 Krause et al 307-157 X 3,242,486 3/1966 Corbel.
3,319,116 5/1967 Schick 315-83 3,331,065 7/ 1967 McDonald 15 ROBERT K. SCHAEFER, Primary Examiner T. B. JOIKE, Assistant Examiner U.S. CI. X.R. 20 240-2, 123; 307-140, 157, .252; 328-5; 340-258