| 摘要 |
PURPOSE:To improve a battery holding time by controlling a power supply by the presence or absence of a received infrared ray signal, and cutting the supply of a power source at the time of the absence of the input signal. CONSTITUTION:The infrared ray signal transmitted by a wireless transmission is received and photoelectric-converted by a light receiving element 1, amplified by an amplifier circuit 2, and inputted to a signal processing circuit 3. The received signal is demodulated by the signal processing circuit 3, turned into a digital audio signal, turned into an analog audio signal by a digital/analog converter 4, power-amplified by an audio amplifier circuit 5, and a speaker 6 is driven. The power is supplied from a power source 10 through a switch 11 to the amplifier circuit 2, signal processing circuit 3, D/A converter 4, and amplifier circuit 5. Then, a microcomputer 9 which judges the presence or absence of the input signal, opens the switch 11 at the time of judging the absence of the input optical signal, the power is not supplied to the main receiving circuits, and the operation is stopped. Thus, the battery holding time is improved. |
