| 摘要 |
PROBLEM TO BE SOLVED: To enable keybuttons to be pressed always in a certain direction so that the switch is turned on/off steadily, even if the keybuttons are pressed in abnormal manner such as 'corner pressing' by one hand. SOLUTION: A dome sheet 3 having a plurality of dome parts 31 is arranged on a printed-circuit board 2 on which a plurality of fixed contact points 32 are formed. A movable contact point 32 is formed on the backside of the dome part 31. A key sheet 1 having a keybutton 11 is formed on the dome sheet 3. An upper side protrusion 111 is formed at the top end side on the top face of keybutton 11 and a lower side protrusion 112 is formed at the position slightly to the side of the upper side protrusion from center on the lower face of the keybutton. The switch is housed in the case 5 having an opening 51 so that the top face of the upper side protrusion 111 may be higher than the surface of the case.
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