Patent ID: 6953240
Filing Date: 2005-10-11
Classification: B41J

Abstract:
1. A normally closed microswitch for controlling an electrical circuit comprising; (a) a base element formed with a depression having opposing anchor edges, said opposing anchor edges defining a central plane; (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 formed to have a residual shape bowing outward from the central plane in a first direction away from the second layer and towards the first switch 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 initially bowing farther outward in the first direction, then, due to thermomechanical torque's acting at the opposing anchor edges, reversing and snapping through the central plane to bow outward in a second direction toward the second layer, moving the control electrode out of contact with the first switch electrode thereby opening the electrical circuit, and then relaxing to the residual shape, closing the electrical circuit as the temperature decreases thereof.