| 摘要 |
PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of preventing the degradation of an image caused by the fluctuations of the beam spot diameter of laser beam. SOLUTION: An image forming apparatus uses a delay circuit 1, an exclusive logical sum circuit 2 and an integration circuit 202 to generate a saw-tooth wave of which the cycle is equal to the cycle of an image clock and, after an image data signal is converted to an analogue value, the analogue value is compared with the saw-tooth wave to form a PWM signal and the ratio of the output current corresponding to the incidence quantity of laser beam detected by a photodiode PD to a pulse wave height value is calculated and a pulse width correction signal is supplied from an image processing circuit until the difference with a reference value defined by an image clock becomes '0' and a laser diode is driven by the PWM signal corrected in pulse width to record an electrostatic latent image. As a result, an image uniform in density can be provided.
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