| 摘要 |
PURPOSE:To maintain good contrast at all times by providing a variable resistor for dimmer controlling, converting its output voltage into a digital value and inputting it into an MPU, to change the luminance of a vehicle-loaded equipment indicating part, in many stages. CONSTITUTION:The captioned circuit, when used in a vehicle-loaded electronic tuning radio receiver consisting of an antenna 1, a high frequency stage 2, a mixer 3, an intermediate frequency stage 4, a detecting circuit 5, a low frequency amplifier 6, and a speaker 7, has a manually operatable variable resistor R1, and an A/D converter 20 which converts the output voltage V of the resistor R1 into a digital value and input it into an MPU 11. And, when a digital value corresponding to the operated quantity of the variable resistor R1, is inputted into the MPU 11 from the A/D converter 20, the duty control of the luminance of a display 13 can be made in accordance with the digital value by means of the MPU 11. Thereby, the control of luminance can be carried out in many stages, to maintain good contrast at all times.
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