| 摘要 |
<p>PURPOSE:To reduce friction between a key side fulcrum part and a key support member side fulcrum part and a noise when a key is played by making the support part on the side of the key support member and the fulcrum part on the key side come into point contact having plural contact points on the same spherical projection circumference. CONSTITUTION:The projection fulcrum part 11 formed of a spherical surface integrally with the rear end part of the key 2 abuts on the left and right surfaces 9 and 10 of the recessed fulcrum part 8 on the side of the key support member 7. Further, the left and right surfaces 9 and 10 of the recessed fulcrum part and the projection fulcrum part 11 come into spot contact having two contact points 12 on the same spherical projection circumference while positioned on an axis L crossing the lengthwise axis of the key 2 at right angles, and both the contact points 12 and 12 face each other. Then the key 2 can freely rotates at a fine angle around the abutting positions between the left and right surfaces 9 and 10 of the recessed fulcrum art 8 and the projection fulcrum part 11, i.e., the contact points 12 within a range of motion wherein the key is used as a keyboard in the up-down and left-right directions and rolling direction.</p> |
