| 摘要 |
PURPOSE:To attain high-quality exposure without the irregularity of exposure by changing and correcting the angle of reflection of a mirror according to a positional error signal outputted from a velocity conversion circuit. CONSTITUTION:The speed of a rotating drum 6 is detected by a tachometer generator 8 connected to the rotary shaft of the drum 6, and the detected speed signal is converted into the positional error signal by the velocity conversion circuit 9. That is, the speed signal is converted into a speed error signal by a subtraction circuit in the circuit 9, and further converted into the positional error signal of the drum 6 by an integration circuit. When the speed is high, the speed signal is converted into the positional error signal having a positive polarity and when the speed is low, it is converted into the positional error signal having a negative polarity. An actuator 10 changes the angle of reflection of a reflection mirror 11 according to the positional error signal by the circuit 9, and when the positional error signal is not positive, the position of the mirror 11 is changed in a direction shown by an arrow B and when it is not negative, that of the mirror 11 is changed in a direction shown by an arrow C. Thus, based on the error signal, the optical path of a light beam is varied and an exposure position is changed corresponding to the irregularity of speed. |
