Abstract: A weight (4) rotates with a shaft (5) as a rotational center during acceleration detection. A rotor (1) fixed on the weight (4) rotates integrally therewith. A first cam portion 1a of noncircular configuration on the rotor (1) contacts a plate spring (2) and a second cam portion (1b) of semicircular configuration contacts a plate spring (3), urging constantly the rotor (1) in a direction opposite to rotation direction thereof. The plate springs (2) and (3) have a contact-point function, and when the rotor (1) rotates in resistance to urging force thereof, contact is made with a contact points (2a) and (3a) on the plate springs (2) and (3) due to action of the first cam portion (1a) and second cam portion (1b), and the contacting state thereof is detected via a plate (6) and plate (7) as an electrical signal.

Abstract: When an acceleration more than a predetermined level is applied to a weight, a rotational moment is applied to a center of gravity of the weight, and therefore, the weight rotates around a shaft as a rotational center in a direction to be opposite to an elastic force given by plate springs. At this time, a rotor rotates in accordance with the rotation of the weight, the plate springs contacting respectively first cam and second cam move so as to narrow the clearance between the plate springs. When the rotor is rotated to a predetermined angle, contact points of the plate springs contact, and the contact state can be detected as an acceleration detecting signal through signal-output terminals. A stopper has two ends, and the two end are fixed to a cover to have a clearance portion between the cover and the stopper. When the weight and the stopper contact, the stopper is bent to the clearance portion side to absorb a shock due to the rotation of the weight.