Patent ID: 7485818

Claim:
A tilt switch comprising: a base including an upright support that has a top face, first and second side faces extending downwardly and respectively from two opposite ends of said top face, a lower groove formed in said top face between said first and second side faces, and two opposite first and second lower passage holes formed in said top face proximate to said first and second side faces, respectively, and communicated with said lower groove; an emitter including an emitter main body mounted on said base proximate to said first side face, and an emitter head aligned with said first lower passage hole to emit a light signal; a receiver to receive said light signal, and including a receiver main body mounted on said base proximate to said second side face, and a receiver head aligned with said second lower passage hole; a cover body including a top wall, two spaced-apart first and second press pieces projecting downwardly from said top wall to press against said top face of said upright support proximate to said first and second side faces, respectively, and an upper groove formed between said first and second press pieces and cooperating with said lower groove to define a chamber, said first press piece having a first upper passage hole aligned and complementing with said first lower passage hole to define a first light passage for passage of said light signal, said second press piece having a second upper passage hole aligned and complementing with said second lower passage hole to define a second light passage for passage of said light signal, said light signal propagating along a light path passing through said chamber from said first light passage to said second light passage; a ball member rollable within said chamber to block or unblock said light path, wherein each of said first and second light passages has a width in a top-to-bottom direction, said width being smaller than a diameter of said ball member.