| 摘要 |
PURPOSE:To allow a stepping motor in shutter operation with less power consumption to generate sufficient stopping torque stably, by supplying the stepping motor for stopping down a shutter with a less current than in operation. CONSTITUTION:During shutter operation, a switch SW8 associated with shutter is turned on. Then, transistors TR1-TR4, etc., are turned off at a potential inverted to an optional level through the switch SW8, and a driving circuit DR supplies a less current than during the operation to a stepping motor SM1 for controlling an aperture AP through resistances R10-R16. By the less current than during operation supplied only at need, the stepping motor generate sufficient stopping torque stably to prevent aperture variation due to oscillation during shutter operation. |
