| 摘要 |
PURPOSE:To make possible the control of the fluctuating width of the quantity of transmitted light within a prescribed range by detecting the fluctuation of the quantity of the transmitted light of a liquid crystal cell and changing the frequency of a driving signal according to the fluctuation magnitude of the detected quantity of the transmitted light. CONSTITUTION:A liquid crystal driving circuit 3 forms and outputs the driving signal of the frequency based on the clock signal from a clock generating circuit 12 and supplies the same to a liquid crystal display part 4. The quantity of the transmitted light of a liquid crystal display part 4 is detected by an optical sensor 5. The peak value of the quantity of the light is detected from the change of the quantity of the light detected by the sensor 5 and the correction frequency is discriminated by the peak value and the preset peak value. The clock signal corresponding to the correction frequency is generated from the circuit 12 in accordance with the result of the discrimination and is impressed to the display part 4. More specifically, the frequency of the driving signal to be impressed to the display part 4 changes with the change of the quantity of the light transmitting the display part 4. The fluctuation width of the quantity of the transmitted light is thereby controlled within the prescribed range.
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