| 摘要 |
PURPOSE:To perform scanning in parallel at equal intervals by storing preliminarily the steady-state deviation of a scanning optical deflector and the extent of steady axial deflection of a rotary axis and obtaining the extent of deflection to be corrected in accordance with these stored values and the output of an axial deflection detector. CONSTITUTION:A position detector 18 is put on a scanning line 7, and a rotary polygonal mirror 6 is rotated, and the steady-state deviation (a) of a scanning light beam detected by the detector 18 is stored in a memory 17, and the extent (b) of steady axial deflection outputted from an axial deflection detector 14 is stored in a memory 19. When a scanning face is placed instead of the detector 18 and a motor 9 is driven, a subtractor 20 reads out the extent (b) corresponding to a rotation angle theta and outputs the difference between the extent (b) and an output (b+c) of the detector 14, namely, the extent (c) of non-steady axial deflection. This extent (c) is converted to a non- steady deviation (d) by an operator 21. This deviation (d) is added to the deviation (a) in the memory 17 by an adder 22 to output overall deviation (a+d). A correcting optical deflector 4 is driven by a driving circuit 23 so that a light beam 2 is deflected by an extent corresponding to the deviation (a+d) to cancel the unevenness of scanning. |
