| 摘要 |
PURPOSE:To automatically control the coloring density by changing the frequency and the duty ratio of a pulse alternating square wave voltage with the quantity of incident light. CONSTITUTION:The pulse alternating square wave voltage consisting of a square wave voltage 1 for coloring having a pulse width (a) and a square wave voltage 2 for achromatization having a pulse width (b) is applied to an EC element to alternately color and achromatize the EC element, and the incident light is received by a photoelectric cell and its resistance is changed correspondingly to the quantity of incident light to control the frequency and the duty ratio of the pulse alternating square wave voltage. For example, the pulse width (a) of the square wave voltage for coloring is fixed (10msec) and the pulse width (b) of the square wave voltage for achromatization is changed to 0.5-5msec. Thus, the coloring density of the EC element is automatically controlled to keep an EC dazzleproof mirror at a prescribed reflection factor.
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