| 摘要 |
PURPOSE:To realize the miniaturization and cost reduction of an apparatus, by driving an instrument, which displays information by the mechanical displacement of an indicator, by a pulse width modulation signal. CONSTITUTION:In a driver seat terminal 1, the digital signal sent from the other terminal (not shown in the drawing) in a car through a transmission line 3 is received by a transmitting and receiving circuit 4 to drive the indicator type instrument M of an instrument panel. Instruments M-1-M-n are connected to a drive power source and switching circuit 10-1-10-n and a constant current equal to or more than rated full scale is cyclically and intermittently flowed over a time shorter than the mechanical response time of each instrument. The switching circuits 10-1-10-n are turned ON or OFF by flip-flops 9-1-9-n set or reset in the duty ratio corresponding to the input digital value by a microprocessor 7. By this method, a D/A converter is dispensed with and the miniaturization and cost reduction of the apparatus can be realized.
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