| 摘要 |
A switch employing such magneto-sensitive switching element as, for example, reed switch or the like and generally used for crime prevention purpose with a high reliability, wherein the switching element is initially set in either one of its ON and OFF states by a permanent magnet disposed adjacent the element and rotatably about its central axis perpendicular to its longitudinal axis and such initially set state of the element is turned to the other state to actuate an alarm device when another permanent magnet mounted, for example, to a door approaches the rotatable magnet and magnetically varies initial relationship of the rotatable magnet to the element.
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