A tilt switch includes a housing body with a modular concavity, light emitting and receiving units disposed in the housing body, a modular insert body inserted into the concavity and having an entry hole for admitting entry of only a portion of a light beam emitting from the emitting unit so as to form...http://www.google.fr/patents/US6800841?utm_source=gb-gplus-shareBrevet US6800841 - Tilt switch
