| 摘要 |
PURPOSE:To minimize deterioration by forming an abutting part, which is wider than the flank member of a key in the thickness direction, at each stopper part. CONSTITUTION:Expanded abutting parts 16 which are expanded in thickness- directional width are formed at end part of an upper-limit stopper 4 and a lower-limit stopper 7. The upper-limit stopper 4 abuts on a buffer member 15 via the upper edge part including the expanded abutting part 16. Similarly, the lower-limit stopper 7 abuts on the buffer member 5 via the lower edge part including the expanded abutting part 16. Here, expanded abutting parts 15 of adjacent keys are dispersedly arranged to increase the abutting area, and the range of abutting on the buffer member is increased by the dispersion of abutting positions to relax concentration on the buffer member, there by suppressing the deterioration of the buffer member. Further, the quantity of intrusion into the buffer member at the time of striking is reduced and made uniform because of the increase in the area and the top surfaces of keys are prevented from becoming uneven in level. |
