| 摘要 |
PURPOSE:To perform visually smooth dimming control by integrating the square waveform of a supply voltage waveform and subtracting the integral output from the peak value of the integral waveform to obtain a dimming characteristic signal. CONSTITUTION:A series circuit consisting of two SCRs connected in anti-parallel and an illuminating load L is connected to an AC power source AC, and phases of SCRs are controlled by a control circuit P1 in accordance with a control signal based on a sliding piece K of a fader F to perform the dimming control. In this case, a phase signal generating part U is provided to integrate the square waveform of the supply voltage waveform, and the integral output is subtracted from the peak value of the integral waveform to obtain the dimming characteristic signal. Angles of conduction of SCRs are set by this dimming characteristic signal and said control signal. Thus, the set quantity of the fader F and the quantity of light of the illuminating load L correspond to each other linearly to perform the visually smooth dimming control.
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