Patent ID: 7812275

Claim:
An automatically reset switch, comprising: a switch base; a stationary contact fixed to the switch base; a control knob attached to the switch base to be movable between a first operating position and a second operating position; a movable contact holder which moves between first and second actuation positions in associating with the movement of the control knob to the first and second operating positions; a movable contact which is supported by the movable contact holder and comes into contact with the stationary contact when the movable contact holder moves to the second actuation position; and a return urging means provided between the control knob and the switch base so as to urge the control knob toward the first operating position, wherein in that the control knob is supported on the switch base via a first pivotal shaft so as to be tiltable between the first and second operating positions; wherein the movable contact holder holds the movable contact and is supported on the switch base, via a second pivotal shaft substantially parallel with the first pivotal shaft, so as to tilt between the first and second actuation positions; wherein the movable contact holder is formed with first and second arms which project in opposite directions with the second pivotal shaft therebetween; wherein a sliding surface is formed between the first and second arms; wherein the return urging means comprises a control plunger which is slidably fitted to the control knob so as to cause a tip end thereof to slide on the sliding surface corresponding to the tilting of the control knob, and a return spring which urges the control plunger in a direction to abut on the sliding surface; wherein the control plunger is arranged such that, when the control knob tilts to the first and second operating positions, the tip end of the control plunger moves on the sliding surface to left and right sides with respect to a plane extending between axes of the first and second pivotal shafts, and such that the repulsive force of the return spring constantly urges the control knob toward the first operating position; and wherein a distance over which the tip end of the control plunger moves from the plane to the second arm when the control knob tilts to the second operating position is smaller than a distance over which the tip end of the control plunger moves from the plane to the first arm when the control knob tilts to the first operating position.