| 摘要 |
PROBLEM TO BE SOLVED: To detect a quality of vibration at a high level without excessively complicating a manufacture of a keyboard instrument.SOLUTION: Sensors 40A, 40B, and 40C are constituted as a coaxial cable having a core wire, a piezoelectric element film covering the outside of the core wire, and an outer conductive layer consisting of a braided wire further covering the piezoelectric element film from the outside. The outside of the outer conductive layer is protected by a cover part made of polyethylene. The sensors 40A, 40B, and 40C are disposed respectively along each extending direction of a long bridge 14, a short bridge 15, and a short bridge leg 25 so as to be arranged superposed on the long bridge 14, the short bridge 14, and the short bridge leg 25 viewed from a direction perpendicular to a sound board. The sensor 40A is embedded across the whole length of a concave groove formed on a lower surface of the long bridge 14, in a state of being always in contact with the concave groove and the sound board 12 and also in a state of always slightly receiving a compression stress from the outer peripheral side. |
