| 摘要 |
PURPOSE:To eliminate the need for a manual imaging operation and to permit automatic setting of a projection lens to a focused point by adjusting the focal length of the projection lens in accordance with a signal which detects the light emitted by a light emitting element and reflected from a microfilm surface. CONSTITUTION:Focusing of the projection lens 4 is automatically executed by reflecting the light emitted from the light emitting elements on the microfilm surface and receiving the same by a light receiving elements. More specifically, a system controller 13 outputs a light emission signal (a) of a semiconductor laser 10, a control signal (b) to a CCD driving circuit 14 and a control signal C to a motor control circuit 15 as a control means. The CCD driving circuit 14 drives a CCD 11 to deliver an output to an amplifier 12 by the control signal (b) from the system controller 13 and a motor driving circuit 15 outputs a driving signal (d) of a pulse motor 16 according to the control signal C from the controller 13. The lens 4 is then moved upward and downward according to the revolutions of the motor 16 by a lens driving device 17. The projection lens is thereby automatically set.
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