| 摘要 |
PROBLEM TO BE SOLVED: To obtain the good touch equiv. to the touch of an acoustic piano with compact constitution by controlling the magnetic force of electromagnets, thereby controlling the touch weights of corresponding keyboards. SOLUTION: An electromagnet circuit 5 is disposed in the rear apart of keyboard chassis 6 so as to face a metallic plate 3 and internally has four pieces of the electromagnets 5a to 5d. The magnetic force on the respective electromagnets 5a to 5d acting on the metallic plate 3 is controlled by a control circuit 10. Namely, the metallic plate 3 is attracted downward by the magnetic force of the respective electromagnets 5a to 5d to provide the resistance force against the ascending of the material plate 3 by depression of the keyboards 2. The tough weights of the keyboards 2 are controlled by changing the magnetic force of the respective electromagnets 5a to 5d. The touch weights of the keyboards 2 are changed by controlling the magnetic force in such a manner and, therefore, the good touch feels are obtd. with the compact constitution. |
