Infrared remote control circuit

• US 6,236,484 B1
• Filed: 06/24/1998
• Issued: 05/22/2001
• Est. Priority Date: 06/25/1997
• Status: Expired due to Term

• Current Assignee: Renesas Electronics Corporation
• Original Assignee: NEC Corporation
• Inventors: Isoda, Michio
• Primary Examiner(s): Pascal, Leslie
• Assistant Examiner(s): Bello, Agustin
• Application Number:
  US09/103,901
• Time in Patent Office: 1,063 Days
• Field of Search: 359/142, 359/146, 359/189, 359/184, 359/194
• US Class Current: 398/202
• CPC Class Codes: H04B 10/1141 One-way transmission

Abstract

An infrared remote control circuit comprising an infrared sensing element that receives an infrared modulated wave; an amplifying circuit for amplifying a received signal; a band pass filter that extracts a particular frequency from the received signal amplified by the amplifying circuit; a wave detection circuit for detecting an output signal from the band pass filter; and a waveform shaping circuit for shaping the waveform of an output signal from the wave detection circuit, wherein another wave detection circuit is provided between said first wave detection circuit and the waveform shaping circuit as a second wave detection circuit, and wherein the output from the same current mirror circuit is used as a control signal for both BPF and second wave detection circuit.

Claims

1. An infrared remote control circuit comprising an infrared sensing element that receives an infrared modulated wave;

an amplifying circuit for amplifying a received signal;

a band pass filter that extracts a particular frequency from the received signal amplified by the amplifying circuit;

a wave detection circuit for detecting an output signal from the band pass filter; and

a waveform shaping circuit for shaping the waveform of an output signal from the wave detection circuit, wherein;

another wave detection circuit is provided between said first wave detection circuit and the waveform shaping circuit as a second wave detection circuit, and wherein the output from a same current mirror circuit is used as a control signal for both the band pass filter and the second wave detection circuit.

2. An infrared remote control circuit according to claim 1 wherein the second wave detection circuit comprises a frequency selection circuit and a pulse detection circuit, the waveform shaping circuit comprising a comparator-type waveform shaping circuit, and wherein

an output terminal of an input-offset differential circuit in the first wave detection circuit is connected to an input terminal of a frequency selection circuit in the second wave detection circuit, an output terminal of the, frequency selection circuit being connected to an input terminal of the pulse detection circuit, an output terminal of the pulse detection circuit being connected to an input terminal of the waveform shaping circuit, a first and a second output terminal of the current mirror circuit being connected to the band pass filter for controlling, a third output terminal of the current mirror circuit being connected to the frequency selection circuit for controlling.

3. An infrared remote control circuit according to claim 2 wherein an output signal from the first wave detection circuit is input to a one-shot multivibrator circuit, wherein an output signal from the one-shot multivibrator circuit is input to the frequency selection circuit in the second wave detection circuit, and wherein an output signal from the frequency selection circuit is input to the pulse detection circuit via a delay circuit.

4. An infrared remote control circuit according to claim 2 wherein an output signal from the first wave detection circuit is input to a one-shot multivibrator circuit, wherein an output signal from the one-shot multivibrator circuit is input to the frequency selection circuit in the second wave detection circuit, and wherein an output signal from the frequency selection circuit is input to the pulse detection circuit.

5. An infrared remote control circuit according to claim 2 wherein the pulse detection circuit comprises four D-type flip-flops connected in series, wherein in one of paths, output from each D-type flip-flops is input to a first AND gate through first paths, while the output is input to a second AND gate via an invertor through second paths, wherein:

output from a pulse delay circuit to which the output from the frequency selection circuit is input, output from the first AND gate, and output from the second AND gate are input to a circuit comprising an AND gate, an OR gate, and an R-S-type flip-flop, and wherein;

an output signal from the R-S-type flip-flop is input to the waveform shaping circuit.