| 摘要 |
A reversing plate is provided between a depressing barrel which is engaged with a key top and a membrane contacts on a frame, wherein the reversing plate is bent toward the depressing barrel and, when a depression force applied by the depressing barrel exceeds a predetermined buckling limit, the bending direction of the reversing plate reverses toward the membrane contacts. The reversing plate is made of a plate spring and is composed of a slim peripheral piece which is bent by being provided a bending portion at several positions, a central piece astride in the approximate center of the peripheral piece, and a contact pressing piece provided at the central piece. When the key is depressed, the central piece of the reversing plate is moved under pressure transmitted through the depressing barrel, twisting the peripheral piece. When this twist exceeds the buckling limit, the reversing plate suddenly reverses to buckle toward membrane contacts, thereby pressing the membrane contacts at the contact pressing piece to turn on the switch. When the key is released, the reversing plate suddenly reverses toward the depressing barrel to make the twist of the peripheral piece return, thereby the contact pressing piece parting from the membrane contacts to turn off the switch.
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