REMOTE CONTROL UTILIZING PULSED BEAM OF LIGHT FREQUENCY

• US 3,866,177 A
• Filed: 08/09/1973
• Issued: 02/11/1975
• Est. Priority Date: 08/12/1972
• Status: Expired due to Term

• Current Assignee: Hiroshi Mori, Keisuke Yamamoto, Yukio Kawamata
• Original Assignee: Hiroshi Mori, Keisuke Yamamoto, Yukio Kawamata
• Inventors: Kawamata, Yukio, Yamamoto, Keisuke, Mouri, Hiroshi
• Primary Examiner(s): Yusko, Donald J.
• Application Number:
  US05/387,168
• Time in Patent Office: 551 Days
• Field of Search: 340/171R,171A,171PPF 325/37,40,105,164 343/225 331/111,112,113,153 332/14 329/102,103,105 250/217SS,199 178/DIG.15
• US Class Current: 398/106
• CPC Class Codes: H03J 9/06 using electromagnetic waves other than radio waves, e.g. light

Abstract

Remote control using a signal of a high frequency which is further chopped with a low frequency. The adoption of a doubly modulated signal can effectively eliminate the possibility of mis-operations. Such a signal can be generated by a combination of an astable multivibrator including two transistors and oscillating at a frequency, and a resonance circuit connected to the output side transistor so that it oscillates at a higher frequency when the output transistor is conductive. The received signal is first demodulated with respect to the high frequency through a detection circuit for the high frequency and then to the low frequency through removal of signal components of other frequencies.

Claims

1. A remote control system including a transmitter and a receiver, said transmitter transmitting a remote control light signal for controlling a distant controllable device such as a television receiver:

said transmitter comprising light generating means for generating and directing the remote control light signal toward said receiver for controlling said controllable device, oscillator means for modulating said light signal at a high frequency, multivibrator means having at least two transistors for intermittently operating said oscillator means at a low frequency to modulate the high frequency modulated light signal at the low frequency, wherein said oscillator means is in common with at least one of said two transistors of said multivibrator means; and

said receiver comprising receiver means for receiving the high frequency modulated light signal further modulated at the low frequency transmitted from said transmitter, signal selection means for selectively taking out only a first signal of a frequency equal to said high frequency from the received light signal, detector means for detecting a second signal, corresponding to the low frequency, from said first signal to generate a corresponding output signal, and means for controlling said controllable device by the output signal.

2. A system according to claim 3, wherein said multivibrator means includes a first transistor having a base applied with a bias voltage and a collector and an emitter connected with respective first and second resistors, a second transistOr connected to said first transistor and having an emitter connected in series with a third resistor, and capacitors connected respectively between the first transistor collector and a base of said second transistor, and between the emitters of said first and second transistors;

and said oscillator means comprises a resonance circuit connected to the second transistor collector and oscillating at a high frequency when said transistor is conductive.

3. A system according to claim 1, wherein said light generating means includes a luminescence diode and wherein said receiver means includes a phototransistor.

4. A system according to claim 1, wherein said means for controlling includes an integrating circuit for integrating said output signal and generating a voltage when the integrated signal is above a predetermined level and when this output signal has a frequency which is the same as said low frequency and is repeated for more than several cycles, and a circuit for operating the controllable device when the voltage is generated by said integrating circuit.

5. A system according to claim 1, wherein said oscillator means further comprises switch-over means for selectively enabling the generation of at least two high frequency signals, wherein said signal selection means includes at least two signal selection circuits corresponding to said at least two high frequencies and further comprising a detector means and means for controlling for each of said two signal selection circuits to enable the remote control of at least two controllable devices.

6. A system according to claim 1, wherein said receiver means includes a transducer circuit for transducing the light signal into an electric signal, said signal selection means includes a signal selection circuit for selecting a signal having the same frequency as said electric signal and said means for controlling includes an integrating circuit for integrating said output signal and generating a voltage when the integrated signal is above a predetermined level and when said output signal has a frequency which is the same as said low frequency and continues for at least several cycles and a circuit for operating the controllable device when the integrating circuit generates the voltage.

7. A system according to claim 4 further comprising a clamping circuit connected between said integrating circuit and said detector means for referring said output signal to a predetermined level so as to provide an accurate integration output.

8. A system according to claim 4 further comprising a differentiating circuit connected between said detector means and said integrating circuit for removing any output signal from said detector means except said output signal.

9. A system according to claim 1 wherein said multivibrator means includes a first transistor having a base applied with a bias voltage and a collector and an emitter connected with respective first and second resistors, a second transistor connected to said first transistor and having an emitter connected in series with a third resistor, and capacitors connected respectively between the first transistor collector and a base of said second transistor, and between the emitters of said first and second transistors;

and said oscillator means comprises a resonance circuit connected to the second transistor collector and oscillating at said high frequency when said second transistor is conductive, said oscillator means oscillating at a higher frequency that the repetition frequency of said multivibrator means.

10. A system according to claim 9 wherein said second transistor is connected to said first transistor as an emitter follower.