| 摘要 |
In the disclosed shutter system, a standby mechanical shutter control operates a shutter in response to failure of the power source of a primary electrical shutter control. Normally the power source enables the electrical shutter control to time and operate the shutter. More specifically, in the disclosure, a standby mechanical timer responds to the failure of a power source to actuate a magnet in an electrical automatic timing arrangement, and operates the shutter for a fixed period.
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