| 摘要 |
PROBLEM TO BE SOLVED: To provide a depression responsive switch unit which can extremely reduce the on-load of a plurality of first step switches, and is hardly affected by deviance in the pressing direction and one-sided depressing. SOLUTION: A pusher 38 formed of a rubber material, a click plate 37, a membrane switch 36s which serves as a second step switch, a reinforcing plate 35, a membrane sheet 34 on which a plurality of first step switches 34s are formed, a key operation base 33 and a knob 32 are sequentially assembled into a case 39. The knob 32 includes a plurality of depressing pieces 32a having on its internal surface a projection 32b which moves into contact with each membrane switch 36s and also includes a marginal portion 32d which is supported by the top surface of the case 39. The knob 32 is thin-walled except for the depressing piece 32a, and the thin-walled portion 32c comprises a thermoplastic elastomer or silicone rubber. The knob 32, the key operation base 33 and the reinforcing plate 35 are secured together. As the depressing piece 32a is depressed, the thin-walled portion 32c which is located therearound becomes flexed, whereby the membrane switch 34s is depressed by the projection 32b to turn the switch on. When the depressing piece is further depressed, the reinforcing plate 35 moves and the click plate 37 reverses, turning the switch 36s on. COPYRIGHT: (C)2005,JPO&NCIPI
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