| 摘要 |
PROBLEM TO BE SOLVED: To provide a supply switching mechanism of fluid pressure having a simple structure and facilitating control, and a sequential expanding and contracting mechanism for a plurality of pins which uses the supply switching mechanism of fluid pressure, and a keyboard instrument having a plurality of keys which uses the sequential expanding and contracting mechanism for the plurality of pins. SOLUTION: The keyboard instrument having the plurality of pins comprises a piston rod 2, a piston 3 having strokes inside a cylinder chamber 4a in proportion to expansion and contraction of the piston rod 2 having a discharged opening 6 of fluid pressure which is connected to a compressed air source formed on the piston rod 2, and a plurality of air passages 7-1, 7-2,..., 7-7, which are formed so that the air passages are opened in sequence to the inside of the cylinder chamber 4a along the direction of a stroke of the piston 3 on a cylinder wall 4 in response to the number and arrangement of the plurality of keys 13 and in which compressed air is supplied in sequence by connecting together with the discharged opening 6 in sequence in proportion to strokes of the piston 3.
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