| 摘要 |
A shutter mechanism includes a drum ( 2 ), a stepping motor ( 5 ), a driver ( 20 ), a microcomputer ( 10 ), a memory ( 16 ), and a load magnitude detection circuit ( 30 ) that detects the magnitude of the load on the stepping motor ( 5 ) when an object such as a shutter ( 3 ) is either wound or unwound from the drum ( 2 ). The microcomputer ( 10 ) can set the upper and lower limit stopping positions of the shutter ( 3 ) by resetting the number of command pulses stored in the memory ( 16 ) when the load magnitude detection circuit ( 30 ) detects an increase in the load at the stepping motor ( 5 ), and storing the number of command pulses output to that point from the memory ( 16 ) when the load magnitude detection circuit ( 30 ) next detects an increase in the load at the stepping motor ( 5 ) after the outputting of the command pulses is next restarted.
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