PULSE WIDTH MODULATION CIRCUIT, OPTICAL WRITER AND IMAGE FORMING DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a pulse width modulation circuit capable of solving a problem that the linearity/reproducibility of a triangle wave or a tooth-shaped wave is not consistent with acceleration of an operating speed and that the gradation of an image is not consistent with acceleration of the operating speed. SOLUTION: The circuit is provided with an analog delay 15 of a fast analog delay circuit constitution having a signal generation means for generating a clock signal to be a reference and a signal inversely proportional to a digital data input signal and a delay quantity generation means for desirably phase- delaying the clock signal based on the signal inversely proportional to the digital data input signal from the signal generation means, a delay quantity control means 16 for controlling the delay quantity of this part 15 and a modulation signal generating means 17 for generating a modulated signal given pulse width modulation from a pulse and the clock signal from the part 15. Thus the circuit can cope with the case of a high operating speed and can realize the high gradation of an image, etc.