| 摘要 |
Electric switching apparatus having an adjustable differential switching action. A two-state switching device, for instance a relay, assumes a state dependent on the response of a pair of photoelectric cells which, in dependence on the position of a movable vane, are illuminated by a lamp. The switching device is controlled by the cells through a circuit having a switching differential, that is exhibiting hysteresis or backlash, such that switching occurs only when both cells become shielded from the light or exposed to it. The two cells are movably mounted such that the distance the vane has to move to produce switching, and hence the differential switching action, is adjustable.
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