| 摘要 |
PURPOSE:To make an optical scan of good quality by correcting an electric signal with the control means of an actuator for a cylindrical lens according to the detected temperature of a sensor and compensating the temperature characteristics of the actuator. CONSTITUTION:The temperature TA of the actuator 7 is detected by the sensor 8A, the temperature TL of a laser as a light source 1 is detected, and a voltage V(z) is stored in a ROM 13 according to those detected temperature values. A synchronizm detector 10 reads out information with a synchronous clock which is generated every time deflected luminous flux is detected and drives the actuator through a D/A converter 14 and a driving circuit 15 to move a cylindrical lens 2 on the optical axis, thereby removing the curvature of field in a subscanning direction. Compensated voltage signals VL(z) and VAL(z) when wavelength variation takes place by variation in the laser temperature TL and when the changes in the operation characteristics of the actuator 7 and the wavelength of the laser 1 occur are also read out of the ROM 13 as neces sary. This constitution uniforms the light spot diameter in the subscanning direction with extremely high accuracy, so the optical scan of good quality is attained. |
