Patent ID: 7429708

Claim:
A safety switch, comprising: a body; a fixed pair of contacts fixed in position in the body; a contact plunger provided with a bridge contact extending across the contact plunger and protruding from sides of the contact plunger, the contact plunger being moveable to move the bridge contact into and out of electrical connection with the fixed pair of contacts; a biasing element, arranged to bias the contact plunger towards a control mechanism and to bias the bridge contact of the contact plunger toward the fixed pair of contacts; the control mechanism being engageable with an actuator, and being moveable to control movement of the contact plunger upon engagement or withdrawal of the actuator, the control mechanism being moveable from a first configuration, where the control mechanism resists movement of the contact plunger and keeps the fixed contacts and the bridge contact out of electrical connection with one another, to a second configuration, where the control mechanism allows the contact plunger to move to bring the bridge contact into electrical connection with the fixed pair of contacts, and wherein the safety switch further comprises: a signal emitter and a signal detector positioned in the body; a structure between the contact plunger and the control mechanism arranged to selectively allow or prevent passage of an emitted signal from the signal emitter to the signal detector depending on a position of the structure relative to the signal emitter and detector; and control circuitry in connection with the signal detector, and arranged to generate a control signal if the emitted signal is not detected by the signal detector.