NORMALLY CLOSED SMALL VIBRATION SENSOR

PROBLEM TO BE SOLVED: To provide a nondirectional normally closed small vibration sensor in which a mounting operation of an electrode member occupying the greater part of an assembling operation is easy, whose structure is simple and strong, which can be miniaturized as a whole, whose mass productivity is increased so as to be provided at low costs, which is rich in durability and abrasion resistance, and which is of high reliability. SOLUTION: The sensor is composed of a case C in which a first electrode plate B having a circular hole 1B in a diameter smaller than that of circular holes 1A, 1B in a pair of front and rear molded insulators A1, A2 is inserted and mounted between the pair of insulators A1, A2, in a state that respective center lines of the circular holes are made to agree with each other and in which both front and rear ends are opened; a second electrode plate D1 and a third electrode plate D2 which cover both front and rear ends of the case C; and a conductive sphere E. The conductive sphere E always comes into contact with the electrode plate B and the electrode plate D1 or D2 in a standstill state irrespective of its posture so as to set the electrode plates to continuity, and, when it is vibrated, the conductive sphere is moved so as to repeat its continuity and its noncontinuity irrespective of its vibration direction. COPYRIGHT: (C)2003,JPO