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Publication numberUS3621356 A
Publication typeGrant
Publication dateNov 16, 1971
Filing dateSep 15, 1969
Priority dateSep 15, 1969
Publication numberUS 3621356 A, US 3621356A, US-A-3621356, US3621356 A, US3621356A
InventorsOn Kwan Chi
Original AssigneeOn Kwan Chi
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Photocell control circuit for motor-operated toy
US 3621356 A
Abstract  available in
Images(2)
Previous page
Next page
Claims  available in
Description  (OCR text may contain errors)

United States Patent 1 3,621,356

[72] inventor Kwan Chi 0n Primary Examiner-Gris L. Rader 1800 Grant St., Berkeley, Calif. 94703 Assistant Examiner-Robert .1. Hickey [211 App]. No. 857,912 Attorney-Lane, Aitken, Dunner & Ziems [22] Filed Sept. 15, 1969 [45] Patented Nov. 16, 1971 ABSTRACT: An electric circuit responsive to a difference In the intensity of radiation, such as light, between two positions, for controlling the operative state of a load. The circuit in- [54] PHOTOCELL CONTROL CIRCUIT FOR MOTOR cludes a pair of series-connected photocells which provide the OPERATED TOY input to a solid state amplifier which includes an output stage 14 CW4 Drawing acting as a switch. in one embodiment, the output switching stage is in series circuit with a source of power and a motor [52] US. Cl. 318/480, mounted on a my. such as a vehicle so that the motor is 46/244 250/2101 318/257 ated when the switching stage is conducting. Feedback means 1111- P are provided in circuit with the amplifier and the switching 1 39/ 12 stage so that the operative state of the load, such as the opera- [50] Field of Search 318/480, ion f the my motor is maintained fl he difi g e i 139, l7, 257; 317/124, 127; 307/1 17; radiation intensity between the first photocell and the second 330/59; 250/208 210; 46/244 C photocell has ceased. In another embodiment. a pair of amplifier paths are provided to control both the actuation and deac- [56] Ranch CM tuation of the load. The circuit may be provided as an at- UNITED STATES PATENTS tachment for a toy model wherein an insulating element capa- 3,293,522 12/1966 Lewis 318/257 X ble of being bypassed by the output switching stage of the am- 2,921,408 1/1960 Leblic 318/480 X plifier is in circuit with the power supply to the motor of the 3,130,803 4/1964 Wiggins... 46/244 C X toy. A modification to the circuit is disclosed wherein the dif- 3,199,005 8/1965 Ashworth 318/16 ference in radiation intensity between the photocells controls 3,218,461 11/1965 Saunders et a1. 250/210 X the movement of the toy in its forward, reverse, left. or right 3,502,883 3/1970 Archer 250/209 X directions without the need for using reversing relays.

PATENTEBunv 16mm 3.621.356

sum 1 0F 2 FIG. I.

INVENTOR CHI ON KWAN ()RNEYS PATENTEDunv 16 IS?! 3.621.356

sum 2 or 2 FIG. 2.

INVENTOR CHI-ON KWAN BACKGROUND OF THE INVENTION This invention relates to a control circuit responsive to a difference in radiation intensity between two positions. More particularly, this invention relates to a control circuit for controlling the operative state of a motor in circuit with a source of power. Still more particularly, this invention relates to a control circuit which is capable of being applied to a toy model having a motor in series with a source of direct current potential for controlling the operation of the toy as a function of a difference in radiation intensity between a pair of photocells in the circuit.

It is often a desire in the electronic arts to control the operative' state of a load by using a source of radiation, for example, light. Such control permits the controlling parameter to be located at a point remote from the load without requiring intervening circuit connections. Thus, the prior art has produced a number of circuits which utilize photoresponsive circuit elements, including solid state devices, to switch a load from one operative state to another.

In such control circuits, it is a continuing problem to provide circuit means which maintain the switched state of the load without requiring that a source of controlling light be continuously provided. MOreover, in certain instances, it has been necessary to provide a plurality of switching circuits to control both the actuation and deactuation of the load, such as a motor, by a source of light.

A known circuit utilizes a photo responsive relay circuit which includes a pair of photocells connected so that the circuit responds to a difi'erence in light intensity between the cells. As is well known, the resistance of a photocell is generally a function of the light intensity incident to the cell. In that particular arrangement, the midpoint of a pair of photocells is connected to the base of a transistor which activates a trigger circuit which in turn controls a relay. The output from a multivibrator in that system, connected in circuit with the amplifier, actuates a relay. The length of time that the relay remains closed depends upon the size of a capacitor in circuit with the relay.

Control of the movement of toys from a location remote from the toy and without need for intervening circuit connections also continues to be a problem, for which the use of a photocell has provided some relief. Thus, arrangements are known for controlling the operation of toys by a source of light remote from the toy. Such solutions have not been without difficulty, however, caused, for example, by the problem of avoiding the undesirable operation of the toy by a change in the ambient light level. In some instances, reflectors and lightshielding structures have been used to avoid this difficulty. Moreover, it has generally been quite difiicult to control the operation of a toy under both dark and light ambient conditions. Thus, toys designed to operate in outdoor sunlight have not operated completely satisfactorily in the somewhat darker indoor environment and vice versa.

The movement of the toy illustrates the need in the art to provide means for continuing the operation of the motor after the incident light has been removed. It is annoying to the operator of the toy when he must follow the toy about, continuously shining light upon the photocell to cause the operation of the motor. Thus, it is also an aim in the art to provide means to cause the continued operation of the toy after the source of light has been removed.

Thus, it is an object of this invention to provide a circuit for controlling the operation of the load in a predetermined manner which is responsive to a difference in the intensity of radiation, for example light, incident upon two control positions.

It is a further object of this invention to provide a circuit responsive to a differential level of radiation which includes means for continuing the switched state of the load after the controlling radiation has ceased.

It is a further object of this invention to provide a lightresponsive circuit for controlling the operation of a toy.

It is still a further object of this invention to provide a lightresponsive circuit which controls both the actuation and deactuation of the motor on a toy, such as a vehicle.

It is still a further object of this invention to provide a photoresponsive electrical circuit which may be applied to known motor-operated toy vehicles so that such toys may be remote controlled.

SUMMARY OF THE INVENTION A circuit which achieves the objects of this invention and overcomes the above-mentioned problems in the prior art comprises a pair of radiation-responsive elements, such as photo responsive solid state devices, for example, photocells, connected in circuit to respond to a difference in incident radiation intensity between the two devices. Amplifier means are in circuit with the photocells for responding to the change in signal level across either of the elements. Switch means, such as a transistor capable of being switched from its nonconductive state to a saturation state is in circuit with the amplifier for controlling the operative state of a load, for example, a motor in series with a source of power, such as may be found in a toy vehicle. It is a feature of the invention that the motor will be controlled by the photoresponsive devices by a predetermined sequence of illuminating or shadowing the light incident on those devices.

In a preferred embodiment, the amplifiers include directcoupled transistors having an output which is connected to a transistor switch. Positive feedback is provided from the output of the transistor switch to the input of one of the transistor amplifier stages to maintain the conductive state of switch and thus the operative state of the load after the dilTerence in light intensity on the photocells has ceased. Second amplifier means, comprising at least a pair of direct-coupled transistor stages, are also connected to the photocells for changing the operative state of the load in a direction opposite to that previously discussed and in response to a predetermined sequence of illuminating or shadowing the light incident on the photoresponsive devices.

Means are also disclosed for utilizing illumination to control both the direction and the steering of the toy vehicle without requiring reversing relays. Output means are provided for the circuit which include an element for disconnecting the motor from the source of power so that the operation of the motor is controlled by the photoresponsive circuit. In this manner, the circuit may be readily added to toys having a source of power and a motor to provide them with a remote-control capability.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a circuit diagram illustrating one form of the invention for controlling the operative state of a motor in series with a source of power;

FIG. 2 is a modified circuit according to the invention for controlling the activation and deactivation of the load in circuit with a source of power supply;

FIG. 3 is an illustration of the invention as applied to a toy model, such as a toy truck; and

FIG. 4 is a circuit diagram showing a further modification of the circuit according to the invention.

DETAILED DESCRIPTION OF THE INVENTION In FIG. 1, input circuit means are designated generally at 10 and comprise a first element, such as a photoresponsive device, for example, a photocell 11 connected to a similar photoresponsive device, for example, photocell l2. Photocells l l and 12 are connected in series across a source of electrical power, for example, a direct-current battery 13 located on a toy model. Positive bias is supplied to the circuit on lead 14 and negative bias is supplied to the circuit on lead 15.

First amplifier means are designated generally at 17 and comprise a first transistor T1 including a base 19, emitter 20 and collector 21 coupled by way of lead 22 to the base 23 of transistor T2. Transistor T1 is biased by the connection of its emitter 20 to the junction of resistors R1 and R2 connected between leads 14 and 15.

Transistor T2 also includes an emitter 24 connected to bias lead 14 and a collector 25. Switching amplifier means designated generally at 27 include a transistor T3 having a base 28 coupled to the collector 25 of transistor T2. Emitter 29 of transistor T3 is connected to the negative bias lead while collector 30 of transistor T3 is in circuit with the load, for example, motor 33, by way of lead 31.

Positive feedback is provided from the collector 30 of transistor T3 to the base 23 of transistor T2 through resistor R3.

Photocells 11 and 12 respond to a variation in the radiation intensity between the cells to control the operation of motor 33. While the source of-radiation will generally be discussed as a source of light, it may be understood that other sources of radiation, visible or invisible, may also be used to actuate an appropriately responsive element.

In operation, photocells 11 and 12 operate to provide a response corresponding to the presence of illumination on one cell, the presence of a shadow on the other cell or a combination of lighting or shadowing which will produce a difference in the light intensity applied to the respective cells. That difference in radiation intensity between the cells will generally be referred to as the difference in radiation between the two positions, or upon the two cells.

When photocell 11 receives light, its resistance decreases. A decrease in the resistance of photocell 11 causes an increase in the magnitude of the positive voltage applied to the base 19 of transistor T] from lead 14. Thus, the base current applied to transistor T1 increases. An increase in current to the base of T1 causes T1 either to conduct or increases its conductivity, depending on its initial state. As T1 conducts, T2 either conducts or increases its conductivity which further causes transistor T3 to conduct toward saturation. As transistor T3 increases conduction, the current in collector 30 increases and provides positive feedback through resistor R3 to the base 23 of transistor T2 to further assist driving transistor T3 quickly into saturation.

A series loop comprises battery 13, motor 33, lead 31, transistor T3, emitter 29 and a portion of the bias lead 15. Thus, the state of conduction of transistor T3 acts as a switch for the operation of the motor 33. When the transistor T3 is off, an open circuit exists and the motor is deactuated. When transistor T3 is driven to saturation, the circuit becomes closed to actuate the motor 33.

The above operation of the circuit will likewise operate, as hereinbefore discussed, by the presence of a shadow on photocell 12 which further causes an increase in its resistance, thus increasing the applied voltage to the base of transistor T1, or by a combination of light applied to photocell I1 and a shadow applied to photocell 12. Moreover, application of light of greater intensity to photocell 11 than the intensity of light applied to photocell 12 will cause the circuit to operate as described.

Positive feedback through resistor R3 causes the circuit to possess a memory capability since transistor T3 will remain in its saturated state by action of the positive feedback after the light differential between photocells l1 and 12 has terminated. Thus, the action of the positive feedback causes the motor 33 to be maintained in its running condition.

Light applied to photocell 12 or a shadow applied to photocell 11 will stop the motor. Each of these conditions causes a more negative potential to be applied to the base os transistor T1 decreasing the base current to transistor T1 and decreasing its conduction. Therefore transistor T2 conducts less causing transistor T3 to conduct less until transistor T3 is driven to its nonconductive state. The action of the positive feedback also assists in driving transistor to its "off" state.

In FIG. 2, circuit elements and connections which correspond to those described in FIG. 1 are identified with like reference numerals so that detailed discussion need not be repeated.

Second amplifier means designated generally at 40 comprise a pair of direct-coupled transistors T4 and T5. Transistor T4 comprises a base 41, an emitter 42 and a collector 43. Base 41 is connected by way of circuit lead 45 to the common junction between photocells 11 and 12. Base 19 of transistor T1 is also connected through lead 45 to the junction between photocells 11 and 12. Transistor T5 comprises a base 47, an emitter 48 and a collector 49 which is connected to the base 28 of transistor T3 by way of lead 51. Transistors T1 and T4 are biased by the series connection of resistors R4, R5 and R6 between bias leads 14 and 15.

The action of amplifier 17 and transistor T3 has been described for the condition in which the photocell 11 is lighted, or photocell 12 is shadowed. Under those same conditions, he transistors T4 and T5 will be rendered nonconductive by the increase in potential applied to the base of transistor T4. If transistors T4 and T5 are conductive when photocell 11 is illuminated, lead 45 becomes more positive and when applied to the base 41 of the transistor T4 would cause T4 to become nonconductive. Thus, current flow to the base 47 of transistor T5 is likewise reduced to render transistor T5 nonconductive.

The circuit of FIG. 2 also permits the operative state of motor 33 to be controlled in a direction opposite to that previously discussed. Thus, to turn motor 33 off after it is running, and held in that operative state by the positive feedback action through resistor R3, a difi'erence in the radiation level on photocells 1 1 and 12in a direction opposite to that previously discussed achieves the desired action as previously discussed. Thus, if photocell 12 is illuminated, its resistance will decrease and the potential at the common junction between photocells l l and 12, and hence, to lead 45 becomes more negative. The application of a more negative voltage to the base 19 of transistor T1 turns transistor T1 off. Simultaneously, application of a more negative voltage to the base 41 of transistor T4 tends to cause transistor T4 to conduct.

An increased conduction of transistor T4 increases the current at collector 43 of transistor T4 which, when applied to the base 47 of transistor T5, turns transistor T5 on. An increase in the collector current from the increased conduction of transistor T5 in the lead 51 is applied to the base 28 of transistor T3 to open the transistor switch T3 in a manner op posite to that previously discussed.

Thus, when transistor T3 is opened, the series circuit involving motor 33 and power source 13 is rendered nonconductive.

One of the capabilities of the circuit is its ready applicability, when packaged in convenient for, to cause a batteryoperated, motorized toy vehicle to be capable of remote control. To this end, an element 60, comprising conductive plate 61, insulating plate 62, and conductive plate 63 in a sandwichlike arrangement is inserted between the motor by way of lead 64 and a source of power 13. Conductive plate 63 is connected by way of lead 65 to the emitter of transistor switch T3 while conductive plate 61 is connected by way of lead 31 to collector 30 of transistor switch T3.

Thus, when transistor T3 is opened, insulating plate 62 prevents the application of power in a complete circuit from source 13 to motor 33. When the switch T3 is closed, insulating plate 62 is bypassed by the conductivity of the transistor T3 to close the circuit and thus actuate motor 33.

FIG. 3 illustrates the ready application of the circuit according to FIGS. 1, 2 or 4 to a toy vehicle, such as a truck designated generally at 70. In this embodiment, photocells 11 and 12 are shown mounted on the cab 71 of the toy vehicle. Element 72 illustratively shows the circuit elements of either FIGS. 1, 2 or 4 in operative connection with batteries 74 and 75 which are equivalent to the power source 13 previously discussed. Motor 76 is shown diagrammatically in phantom outline for driving the rear wheels of the truck in accordance with the conditions of illumination previously discussed. It may be understood that the circuit may be packaged in convenient form, such as encapsulated in epoxy as at 72 and applied to a convenient outside surface of the toy vehicle to expose photocells 11 and 12 to illumination in accordance with the teachings of this invention. By the insertion of element 60, as previously described, between the batteries 74 and 75 in a series circuit with motor 76 via lead 77, the operation of the truck is rendered responsive to the selected level of illumination on the photocells.

MOdification of the circuit as shown in FIG. 4 will permit the control of the vehicle in its forward or backward direction, as well as its left or right direction, depending upon the connection of the motor to the wheels of the vehicle. If the motor is connected to the wheels of the vehicle to provide a driving force, the circuit of FIG. 4 becomes a forward or backward direction control. On the other hand, if the motor is connected by way of appropriate gearing to the wheels of the vehicle, a steering action may be achieved.

The circuit of FIG. 4 operates essentially in accordance with the discussion of FIG. 2 However, an additional transistor switch T6 has its base 53 connected to the collector 49 of transistor T5 and its emitter 54 connected to positive bias 14. The collector 55 of transistor T6 is connected to provide positive feedback by way of resistor R7 to the base 47 of transistor T5.

When photocell 11 is illuminated, or conversely when photocell 12 is shadowed, transistor T1 and T2 conduct more heavily as hereinbefore described to cause transistor T3 to be driven into saturation. When transistor T3 is driven into saturation, a circuit is closed from the collector of transistor T3 to motor 80 and power source 85. On the other hand, under the reverse condition of illumination, transistors T4 and T5 conduct more heavily, driving transistor T6 into saturation to close the circuit between transistor T6, motor 80 and source of voltage 86. When transistor T3 conducts, connection 82 on the motor is more positive than connection 83 so that the motor operates in a first direction. On the other hand, when transistor T6 is saturated, point 82 on the motor is more negative than point 83 on the motor so that said motor is actuated in an opposite direction. It may also be understood that a degree of control is achieved on the state of the motor during the time when transistors T3 or T6 are rendered conductive, but before they reach saturation.

Thus, a photocell control circuit responsive to differences in levels of radiation incident upon a pair of photocell has been described for controlling the operative state of a motor located, for example, on a toy vehicle.

I claim:

1. In a toy model of the type which comprises a source of power in series circuit with a motor, the improvement comprising means responsive to a difference in radiation between two positions for controlling the operation of said motor in a predetermined manner, said means including:

a first element responsive to radiation,

' a second element responsive to radiation in circuit with said first element, said first element and said second element being connected in series across said source of power,

amplifier means in circuit with both of said first and second elements and said motor for actuating said motor in response to a difference in radiation intensity between said first element and said second element wherein said amplifier means comprises a first transistor having a first conductivity and including a base, an emitter, and a collector, the base of said first transistor being in circuit with both said first and said second elements, a second transistor having a conductivity opposite said first conductivity and including a base, an emitter, and a collector, the base of said transistor being in circuit with the collector of said first transistor, and a third transistor having said first conductivity and including a base, an emitter, and a collector, the base of said third transistor being in circuit with said collector of said second transistor, the collector and emitter of said third transistor being in series circuit with said source of power and said motor, said third transistor being driven into saturation to actuate said motor through said power source when said first element and said second element receive a predetennined difference in radiation intensity, and positive feedback means in said amplifier means for causing the continued actuation of said motor afier said difference in radiation between said first element and said second element has ceased wherein said positive feedback means includes a resistor connected from the collector of said third transistor to the base of said second transistor so that said third transistor remains in saturation after the difference in radiation between the said first element and said second element has ceased. 2. The improvement as defined in claim 1 wherein said first element and said second element are each photocells.

3. In a toy model of the type which comprises a source of power in series circuit with a motor, an electrical circuit adapted to convert said toy model into a light responsive toy model, said circuit comprising:

input means responsive to a difference in radiation between two positions for controllingthe operation of said motor in a predetermined manner, said input means including a first element and a second element in circuit with said first element, each of said first and said second elements being responsive to radiation, said first and second elements being electrically connected to said source of power and operative when radiated so that a difference in radiation intensity between said first element and said second element will provide a responsive change in the output signal from said input means,

first amplifier means electrically connected to the output of said input means for amplifying the output signal from said input means'under a first predetermined condition of radiation incident on said first and second elements and providing a first amplifier output signal in response thereto, second amplifier means electrically connected to the output of said input means for amplifying the output signal from said input means under a second predetermined condition of radiation incident on said first and second elements and providing a second amplifier output signal in response thereto,

third amplifier means for controlling the actuation of said motor through said source of power comprising a transistor, including a base, and a pair of conductive electrodes, said base being in circuit with the output of each of said first amplifier means and said second amplifier means and capable of being driven into conductive and nonconductive states in response to a predetermined difference in said radiation intensity between said first and second elements to actuate said motor through said source of power when said third amplifier means is conductive, and to deactuate said motor when said third amplifier means is nonconductive,

positive feedback means in circuit with said third amplifier means and said first amplifier means for sustaining the condition of said third amplifier means after the dif ference in radiation incident on said first and second elements has ceased, and

output means capable of receiving a signal from one of said conductive electrodes of said transistor in said third amplifier means, said output means including means for insulating said motor from said source of power when said third amplifier means is nonconductive and connecting said motor in circuit with said source of power when said third amplifier means is conductive so that the operative state of said motor is controlled by said conductive state of said third amplifier means.

4. An electrical circuit as defined in claim 3 wherein said first amplifier includes a first transistor and a second transistor being in circuit with output of said input means, and

the base of said second transistor being in circuit with the collector of said first transistor.

5. An electrical circuit as defined in claim 4 wherein, the base of said third transistor is in circuit with the collector of the said second transistor.

6. An electrical circuit as defined in claim 5 wherein said positive feedback means comprises a resistor in circuit between said collector of said third transistor and said base of said second transistor.

7. An electrical circuit as defined in claim 5 wherein said second amplifier means includes a fourth transistor and a fifth transistor, each comprising a base, an emitter and a collector, the base of said fourth transistor being in circuit with the output of said input means, and the base of said third transistor being connected to the collector of said second transistor.

8. An electrical circuit as defined in claim 3 wherein said output means further includes an insulating element in circuit with said source of power, said motor and the output of said third amplifier means and arranged so that said insulating element may be bypassed by said third amplifier means when said third amplifier means is conductive to actuate said electric motor upon receipt of the difference in said source of radiatron.

9. An electrical circuit as defined in claim 5 wherein said output means further includes an insulating element in circuit with said source of power, said motor and the output of said third amplifier means and arranged so that said insulating element may be bypassed by said third amplifier means when said third amplifier means is conductive to actuate said electric motor upon receipt of the difference in said source of radiation.

The combination as defined in claim 9 wherein said circuit is further characterized as being capable of attachment to a combination of a toy to provide said combination with remote control capability.

11. The circuit as set forth in claim 3 wherein said first element and said second element are each photocells.

12. In a toy model which comprises a source of power electrically connected to actuate a motor to propel said model, wherein said source of power comprises a first source of electrical potential in series circuit with a second source of electrical potential, and wherein said motor includes at least a pair of terminals for connection in circuit with said source of power to actuate said motor, one of said terminals of said motor being electrically connected to a node common to both of said first and second sources of electrical potential, and wherein the motor is further characterized in that its direction of rotation is responsive to the direction of current flow therethrough, said toy model further comprising an electrical circuit for controlling flow through said motor comprising:

input means responsive to a difference in radiation between two positions for controlling the operation of said motor in a predetermined manner, said input means including a first element and a second element in circuit with said first element, each of said first and said second elements being responsive to radiation, said first and second elements being electrically connected in series with each other and with said source of power and operative when radiated so that a difference in radiation intensity between Said first element and said second element will provide a responsive change in the output signal from said input means,

first amplifier means electrically connected to the output of said input means for amplifying the output signal from said input means under a first predetermined condition of radiation incident on said first and second elements and providing a first amplifier output signal in response thereto,

second amplifier means electrically connected to the output ofsaid input means for amplifyin the output signal from said input means under a secon predetermined condition of radiation incident on said first and second elements and providing a second amplifier output signal in response thereto,

third amplifier means for controlling the actuation of said motor through said source of power comprising a transistor, including a base, and a pair of conductive electrodes, said base being in circuit with the output of said first amplifier means and capable of being driven into conductive and nonconductive states in response to a predetermined difference in said radiation intensity between said first and second elements to actuate said motor in a first direction through said first source of electrical potential when said third amplifier means is conductive, one of said conductive electrodes of said transistor of said third amplifier means being electrically connected to the other terminal of said motor,

fourth amplifier means for controlling the actuation of said motor through said source of power comprising a transistor, including a base, and a pair of conductive electrodes, said base being in circuit with the output of said second amplifier means and capable of being driven into conductive and nonconductive states in response to a predetermined difference in said radiation intensity between said first and second elements to actuate said motor in a second direction through said second source of electrical potential when said fourth amplifier means is conductive,

first positive feedback means in circuit from the output of said third amplifier means to the input of said first amplifier means for sustaining the condition of said third amplifier means after the difference in radiation incident on said first and second elements has ceased,

second positive feedback means in circuit from the output of said fourth amplifier means to the input of said second amplifier means after the difference in radiation incident on said first and second elements has ceased, and

output means for receiving a signal from said one of said conductive electrodes of said transistor in said third amplifier means and said transistor in said fourth amplifier means so that the operative state of said motor is controlled by said conductive state of either of said third amplifier means and said fourth amplifier means by controlling the direction of current flow through said motor.

13. The circuit as set forth in claim 12 wherein said first element and said second element are each photocells.

14. An electrical circuit as defined in claim 13 wherein each of said first amplifier and said third amplifier includes a first transistor and a second transistor, each of said first and second transistors including a base, an emitter, and a collector, the base of each of said first transistors being in circuit with output of said input means, and the base of said second transistor being in circuit with the collector of said first transistor in each of said first amplifier and third amplifier.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION patent 3 ,62l,356 D t d November 16 l97l Inventor-(S) Chi-On Kwan It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Page 1, the name of the inventor should read Chi-On Kwan.

Column 1, line 27, "MOreover should read Moreover Column 3, line 70, "0s" should read of Column 4, line 19, "he" should read the and line 56, "wichlike" should read wich-like Column 5, line 11, "Modification" should read Modification Column 7, line 53, insert the direction of travel of said model by controlling the current before "flow".

Column 8, line 45, insert for sustaining the condition of said fourth amplifier means after "means".

Signed and sealed this 18th day of April 1972.

(SILAL) At best:

EDWARD I-E.FLElCHbJR,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents FORM P0-1O5HO-59) USCOMM-DC scam-Pu USv GOVERNMENT PI'UNYING OFFICE I959 0-356-33l

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Citing PatentFiling datePublication dateApplicantTitle
US3782031 *Feb 23, 1972Jan 1, 1974Creative Patents & Products LtControllable amusement device
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US20130084775 *Dec 14, 2011Apr 4, 2013Innovation First, Inc.Autonomous Vehicle System
DE102013104578B3 *May 3, 2013Apr 30, 2014Tino WernerCollision hazard detection controller for motors of mobile robot, has sensors arranged at different locations on periphery of robot such that combined output signals of sensors are used as input signals for transistors and amplifiers
EP1024871A1 *Aug 31, 1998Aug 9, 2000Parvia CorporationSingle beam optoelectric remote control apparatus for control of toys
Classifications
U.S. Classification318/480, 250/210, 318/257, 446/175, 446/454
International ClassificationH02P7/29, H02P7/18
Cooperative ClassificationH02P7/29
European ClassificationH02P7/29