IR Remote control detector/decoder

• US 4,426,662 A
• Filed: 01/18/1982
• Issued: 01/17/1984
• Est. Priority Date: 01/18/1982
• Status: Expired due to Term

• Current Assignee: Zenith Radio Corporation
• Original Assignee: Zenith Radio Corporation
• Inventors: Zato, Thomas J., Skerlos, Peter C.
• Primary Examiner(s): Masinick, Michael A.
• Application Number:
  US06/340,555
• Time in Patent Office: 729 Days
• Field of Search: 358/194.1, 455/603, 455/607, 455/608, 455/619
• US Class Current: 348/734
• CPC Class Codes: G08C 23/04 using light waves, e.g. infrared
• CPC Class Codes: H03J 1/0025 in a remote control unit remote control tuning in general H03J9/00

Abstract

A pulse code modulated (PCM) infrared (IR) remote control detector/decoder with improved noise immunity particularly adapted for use with a television receiver is disclosed. The IR pulses are modulated by means of a high frequency clock signal in translating the transmitted signal to a higher frequency, more noise immune portion of the IR spectrum. After receipt of the transmitted signal by a signal detector, the high frequency modulation is removed from the pulses which are then decoded. Under the control of a microcomputer, the decoder looks for the start data bit and, if received, the subsequent control instructions. When the data transmission has been decoded, the microcomputer activates the appropriate control outputs to the television receiver'"'"'s tuner system to achieve the desired control function.

Claims

1. In an infrared remote control receiver for processing pulse code modulated control signals generated in response to user selected inputs and modulated by a high frequency carrier signal in translating said control signals to a higher frequency for remotely controlling a plurality of functions in a controlled apparatus by means of a microcomputer responsive to said control signals, a signal detector/decoder comprising:

light detecting means for receiving a remote control signal transmitted by infrared radiation;

a band pass filter tuned to the frequency of said carrier signal and coupled to said light detecting means for filtering said received control signals;

envelope detection means coupled to said band pass filter for demodulating said carrier signal and for recovering said pulse code modulated control signals; and

signal decoding means coupled to said envelope detection means for decoding said pulse code modulated control signals and providing the thus decoded control signals to said microcomputer for controlling said apparatus;

wherein said control signal includes an initialization pulse with said signal decoding means responsive to said initialization pulse for generating and providing a sampling interval signal to said microcomputer and wherein said signal decoding means decodes said pulse code modulated control signals and provides the thus decoded control signals to said microcomputer during said sampling interval.

2. A signal detector/decoder as described in claim 1 wherein said controlled apparatus comprises a television receiver including a tuning system coupled to and responsive to the control signal-initiated outputs of said microcomputer.

3. A signal detector/decoder as described in claim 1 wherein said signal decoder means includes an input latch coupled to said envelope detector and responsive to said pulse code modulated control signal for a predetermined time period following receipt of said initialization pulse, an output latch coupled to said microcomputer for providing said decoded control signals thereto and logic control circuitry coupling said input and output latches for decoding said pulse code modulated control signals and providing a latching signal representative thereof to said output latch.

4. A signal detector/decoder as described in claim 3 wherein said logic control circuitry includes counting means coupled to said input latch and responsive to the state thereof for providing a predetermined delay between the receipt of said initialization pulse by said input latch and the transmission of said decoded control signals by said output latch to said microcomputer.

5. A signal detector/decoder as described in claim 1 wherein said light detecting means comprises a photo diode responsive to infrared radiation incident thereon in combination with an optical filter through which said infrared radiation is transmitted prior to being incident upon said light detecting means.

6. In an infrared remote control receiver for processing a pulse code modulated control signal generated in response to user selected inputs and modulated by a high frequency carrier signal in translating said control signal to a higher frequency for remotely controlling a plurality of functions in a controlled apparatus by means of a microcomputer responsive to said control signal, said control signal including an initialization pulse, a signal detector/decoder comprising:

light detecting means for receiving a remote control signal transmitted by infrared radiation, said light detecting means including a photo diode responsive to infrared radiation incident thereon in combination with an optical filter through which said infrared radiation is transmitted prior to being incident upon said light detecting means;

a band pass filter tuned to the frequency of said carrier signal and coupled to said light detecting means for filtering said received control signals, said band pass filter including a transformer having a primary winding coupled to said light detecting means and a secondary winding, wherein a grounded capacitor is coupled across said secondary winding;

envelope detection means coupled to the secondary winding of said band pass filter for receiving the filtered output therefrom, demodulating said carrier signal, and recovering said pulse code modulated control signals; and

signal decoding means coupled to said envelope detection means for decoding said pulse code modulated control signals and providing the thus decoded control signals to said microcomputer for controlling said apparatus, and wherein said signal decoding means is responsive to said initialization pulse for generating and providing a sampling interval signal to said microcomputer with said decoded control signals provided to said microcomputer during said sampling interval.

7. In an infrared remote control receiver for processing pulse code modulated control signals generated in response to user selected inputs and modulated by a high frequency carrier signal in translating said control signals to a higher frequency for remotely controlling a plurality of functions in a television receiver by means of a microcomputer responsive to said control signals, a signal detector/decoder comprising:

light detecting means for receiving a remote control signal transmitted by infrared radiation;

a band pass filter tuned to the frequency of said carrier signal and coupled to said light detecting means for filtering said received control signals, said band pass filter including a transformer having a primary winding coupled to said light detecting means and a secondary winding, wherein a grounded capacitor is coupled across said secondary winding;

envelope detection means coupled to the secondary winding of said band pass filter for receiving the filtered output therefrom, demodulating said carrier signal, and recovering said pulse code modulated control signals; and

signal decoding means coupled to said envelope detection means for decoding said pulse code modulated control signals and providing the thus decoded control signals to said microcomputer for controlling said television receiver, said signal decoding means including;

an input latch coupled to said envelope detection means and responsive to said pulse code modulated control signals;

an output latch coupled to said microcomputer for providing said decoded control signals thereto; and

logic control circuitry coupling said input and output latches for decoding said pulse code modulated control signals and providing a latching signal representative thereof to said output latch, said logic control circuitry including counting means coupled to said latch and responsive to the state thereof for providing a predetermined delay between the receipt of said initialization pulse by said input latch and the transmission of said decoded control signals by said output latch to said microcomputer.