| 摘要 |
PROBLEM TO BE SOLVED: To mitigate fatigue failure of thin-walled parts by suppressing torsion of keys at the time of key pressing thereby substantially equalizing pressing force per unit area of lower-limit stoppers. SOLUTION: In this keyboard device, when a key is pressed, the key makes downward turning motion with a thin-walled part 10 in the rear of the key used as a hinge and abuts on a lower-limit stopper 7. Torsional stress produced in the thin-walled part 10 by pressing the key is maximum at a left end part 10a while it is relatively small at a right end part 10b. Of left and right side- wall ribs 20, 21 of the asymmetrically formed key 17, the wall thickness t1 of the right side-wall rib 20 situated on the right end part 10b side is formed to be thicker than the wall thickness t2 of the left side-wall rib 21 situated on the left end part 10a side. Although a pressing position P1 of the key 17 is widthwise offset from a center part P2 of the thin-walled part 10, when the key 17 is in a completely pressed state, a difference between contact surfaces of the left and right side-wall ribs 20, 21 with the lower-limit stopper 7 can substantially equalize the amount of displacement of the side-wall ribs 20, 21, and therefore torsion of the key 17 can be suppressed. |
