Patent ID: 7283030

Claim:
A normally closed microswitch for controlling an electrical circuit comprising; (a) a base element formed with a depression having opposing anchor edges; (b) a spacing structure supported by the base element; (c) a first switch electrode supported by the spacing structure, a second switch electrode spaced away from the first switch electrode, and a control electrode for electrically connecting the first and second switch electrodes to close the electrical circuit; (d) a deformable element attached to the opposing anchor edges urging the control electrode into electrical contact with the first and second switch electrodes, the deformable element constructed as a planar lamination including a first layer of a first material having a low coefficient of thermal expansion and a second layer of a second material having a high coefficient of thermal expansion, the deformable element having anchor portions adjacent the anchor edges and a central portion between the anchor portions wherein the flexural rigidity of the anchor portions is substantially less than the flexural rigidity of the central portion and such difference between the flexural rigidity of the anchor portions and the flexural rigidity of the central portion is independent of the control electrode; and (e) apparatus adapted to apply a heat pulse to the deformable element, causing a sudden rise in the temperature of the deformable element, the deformable element bowing in a direction to move the control electrode out of contact with the first switch electrode thereby opening the electrical circuit, and then relaxing, closing the electrical circuit as the temperature decreases thereof.