Patent ID: 7394498
Filing Date: 2008-07-01
Classification: G02F,H04N

Abstract:
1. A liquid-crystal light-amount adjusting device comprising: a driving-pulse generating circuit for generating driving pulses having pulsed voltages; a liquid-crystal light-amount adjusting unit, to which the driving pulses are supplied, for changing an optical transmittance of a liquid crystal according to pulse shapes of the driving pulses; a control circuit for controlling frequencies and duty ratios of the driving pulses; and a temperature detecting circuit for detecting an ambient temperature of the liquid-crystal light-amount adjusting unit and outputting a result of detection to the control circuit, the control circuit changing the frequencies of the driving pulses in accordance with the ambient temperature, wherein the control circuit exercises control so that the driving-pulse generating circuit generates driving pulses for acceleration for a first applying time, having a pulse shape with a first frequency and a first duty ratio, and driving pulses for dimming for a second applying time, having a pulse shape with a second frequency that is different from the first frequency and a second duty ratio that is different from the first duty ratio, wherein the first frequency and the first duty ratio and the first applying time are based upon the driving pulses for dimming and the second applying time is determined from the first applying time, wherein the number of pulses in the driving pulses for acceleration is an integer multiple of one period in the first applying time and the number of pulses in the driving pulses for dimming is an integer multiple of one period in the second applying time.