Remote control system

• US 3,928,760 A
• Filed: 05/07/1974
• Issued: 12/23/1975
• Est. Priority Date: 12/27/1971
• Status: Expired due to Term

• Current Assignee: Mikio Isoda
• Original Assignee: Mikio Isoda
• Inventors: Isoda, Mikio
• Primary Examiner(s): Griffin, Robert L.
• Assistant Examiner(s): Bookbinder, Marc E.
• Application Number:
  US05/467,664
• Time in Patent Office: 595 Days
• Field of Search: 250/199 325/392,394 178/DIG.15
• US Class Current: 398/131
• CPC Class Codes: G08C 23/04 using light waves, e.g. infrared
• CPC Class Codes: H03J 9/06 using electromagnetic waves other than radio waves, e.g. light
• CPC Class Codes: H04B 10/114 Indoor or close-range type systems
• CPC Class Codes: H04B 10/116 Visible light communication

Abstract

A remote control system for use in remote controlling a television receiver is provided in which a light signal is used as the remote control signal. An electroluminescent diode is used to emit the remote control light signal which is amplitudemodulated by a modulating frequency in the ultrasonic frequency range and has a very narrow band of wave lengths. The remote control system is very compact in size and completely free from the erratic operations caused by the noise.

Claims

1. A remote control system for performing a control function by way of a transmission path exposed to ambient light, comprising A. a transmitter assembled within a compact casing, said transmitter including a. an electroluminescent diode for emitting, when energized, a remote control light signal having a relatively narrow spectral width by way of said transmission path;

b. circuit means connected to said diode for energizing said diode at a predetermined ultrasonic frequency said circuit means consisting of an oscillator means comprising an oscillator circuit for oscillating at said predetermined frequency rate, and means for energizing said diode with the output of said oscillator means whereby said remote control light signal is alternately energized and de-energized at said predetermined frequency rate;

c. an electric power source connected to said diode and said circuit means for supplying a low DC voltage thereto to actuate said diode and said circuit means circuit, and d. a light reflector means mounted around said diode for effectively directing said remote control light emitter from said diode to a desired target; and

B. a receiver spaced apart from said transmitter for receiving said light signal by way of said transmission path, said receiver including e. a light receiving means for receiving said remote control light signal transmitted from said transmitter, f. a transducing means for detecting said received light signal and for converting a detected light signal into an electric signal by means of a photoelectric detector, g. an amplifier means consisting of a narrow-band tuning amplifier connected to said transducing means for amplifying said converted electric signal, and for selecting only a signal component of frequency in the ultrasonic region from the light signal transmitted from said diode in the transmitter, h. a detector means connected to said amplifier means for detecting said ultrasonic frequency component and for providing a detector output signal, and i. a means connected to the output of said detector means for performing a control function in response to said detector output signal;

whereby spurious ambient light noises received by said receiver from said transmission path are reduced to eliminate any spurious control which may arise from ambient light.

2. a driving circuit means connected to said oscillator means and connected to said diode for energizing said diode so as to emit said remote control light signal within a duration less than a half repetition period of the oscillation frequency of said oscillator means, c. an electric power source connected to said diode and said circuit means for supplying a low D.C. voltage thereto to actuate said diode and said, d. a light reflector means mounted around said diode for effectively directing said light signal to a desired target, B. a television receiver spaced from said transmitter for receiving said light signal by way of said transmission path, said receiver including:

e. an optical filter mounted to receive said remote control light from said transmitter by way of said transmission path, said filter having a band pass characteristic that corresponds with the emission characteristic of said diode, f. a photodetector mounted for detecting the received light signal after passing through said optical filter, and for converting a detected light signal into an electric signal, g. an amplifier means including a tuning circuit connected to said photodetector for amplifying said converted electric signal and for selecting said predetermined frequency component in the ultrasonic frequency region and providing it as an output signal, h. a detector means connected to said amplifier means for detecting said predetermined single frequency component, and for providing a D.C. voltage signal corresonding to said output signal, i. a D.C. amplifier connected to amplify said D.C. voltage signal, j. a channel selecting device, and k. means for controlling said channel selecting device with the output signal of said D.C. amplifier.

3. A system as defined by claim 1 wherein said diode has an emission characteristic in the infrared region of the spectrum.

4. A system as defined in claim 1 further comprising an optical filter disposed in front of said photodetector, said filter having a bandpass characteristic that substantially matches the emission characteristic of said diode.

5. A system as defined in claim 4 wherein said diode has an emission characteristic in the infrared region of the spectrum.

6. A remote control system for remotely controlling the channel selector of a television receiver by way of a transmission path exposed to ambient light, comprising:

A. a transmitter assembled within a compact casing for generating a light signal suitable for remotely controlling a television channel selector by way of said transmission path, comprising;

a. an electroluminescent diode for emitting, when energized, a remote control light signal having a relatively narrow spectral width in the infra-red region of the spectrum by way of said transmission path, b. a circuit means connected to said diode for energizing said diode at a predetermined single frequency in an ultrasonic frequency region of the spectrum said circuit means consisting of