| 摘要 |
The disclosed shutter time switching device for a rotary shutter is provided with a stepping motor for controlling the opening angle of the rotary shutter. The device includes a driving mechanism for driving the stepping motor in a two-phase driving mode when switching between relatively high shutter speeds and in a single-phase driving mode when switching between relatively low shutter speeds. Optimum responsivity of the switching operation is thus obtained. The stepping motor is rotatable in a first direction and a second direction which is reverse to the first direction. To solve the problem of hysteresis of the motor, the device is provided with a further drive mechanism for driving the stepping motor in the first direction at least one step before a desired step position, regardless of whether the motor has been driven in the first or second direction for switching the shutter speed.
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