| 摘要 |
PURPOSE:To provide the power focusing device which eliminates such a defect of the conventional power focusing device that an operator makes the useless operation to keep rotating a focusing ring without noticing the contact of a focusing lens with an end as no signals are emitted at all even if the focusing lens comes into contact with the end. CONSTITUTION:If the focusing lens 5 does not move any more by coming into contact with the end, the width of the pulses generated from a pulse generator integral with this lens 5 changes and, therefore, this change is detected by a detecting means consisting of a prescribed value generating circuit 9 and a comparator circuit 8 and the driving of a motor for driving the focusing lens is prohibited by a focusing lens driving prohibiting means 10 and a warning generating means 11. Warning is simultaneously generated and is announced to the operator. The useless operation is prevented and the useless electric power consumption is prevented according to this invention. |
