Patent ID: 8875584

Claim:
A pressure-sensitive sensor comprising: a first pressure-sensitive conductive rubber provided inside a housing in such a state that preload is imposed thereon; a second pressure-sensitive conductive rubber provided inside the housing in such a state that the preload is imposed thereon and an external load acts thereon; a load detecting portion for applying voltage to the first and second pressure-sensitive conductive rubbers to determine the external load based on a difference between a first detected value corresponding to electric current flowing through the first pressure-sensitive conductive rubber and a second detected value corresponding to electric current flowing through the second pressure-sensitive conductive rubber; and a biasing portion for pressing the first and second pressure-sensitive conductive rubbers integrally against an inner wall surface of the housing to impose the preload on the first and second pressure-sensitive conductive rubbers, wherein the biasing portion has a movable member provided inside the housing to be movable, and an elastic member for biasing the movable member in a direction in which the movable member is pressed against the first and second pressure-sensitive conductive rubbers, and wherein an opening portion is formed in the housing, and an acting piece is provided on the second pressure-sensitive conductive rubber to project outside of the housing through the opening portion so that the external load will act on the second pressure-sensitive conductive rubber.