| 摘要 |
847,994. Organs etc.; keyboards. PRATT READ & CO. Inc. Feb. 3, 1959 [Oct. 20, 1958], No. 3825/59. Class 88 (2). A keyboard as over each key an arm comprising a rigid portion and a spring portion, the rigid portion providing an upward stop for the key and the spring-portion applying spring tension to urge the key towards the stop. A key comprising parts 16, 17, 18, Fig. 3, is supported on an organ frame 19 having a balancepin 29 and guide-pins 28, 30. The key pivots on a felt 31. A regulating-arm 14, also shown in Fig. 6, comprises a rigid portion 22 and a spring portion 23. U-shaped arms 24, 25 support adjustable screws 26, 27. The arm 14 is supported over the key tail 18 and apertures 32, 33 co-operate with grooves 36 in pins 28, 29. One side 38 of each aperture contacts the upper edge of a groove 36 and the other side 39 contacts the lower edge, Fig. 4. The key may be levelled by turning screw 26, and the biasing force (or " touch ") may then be adjusted by turning screw 27. A switch actuator 20 is operated on depressing the key and energizes a tone generator. Stiffening of the part 20 is obtained by bending down its sides. The ends 24, 25 may be forced down to lock the screws 26, 27 after adjustment. Alternatively, Fig. 7, the free arms 24, 25 may be bent upwards to provide locking. |
