| 摘要 |
PURPOSE:To provide a touch detector which uses optical switches to detect key touch conditions of a keyboard of electronic musical instruments such as a synthesizer, an electronic piano, an electronic organ and a single keyboard. CONSTITUTION:A first switch group 12 which operates at an earlier time of a key movement and a second switch group 14 which operates during an advanced stage of the key movement are respectively made by light emitting diodes and phototransistors whose output conditions vary in accordance with the light receiving conditions. In the keyboard touch detector of an electronic musical instrument, the light emitting diodes (LED) of the first switch group (S1) 12 are constantly emitting light beams and the LEDs of the second switch group (S2) 14 are provided with switchover means that start emitting light beams when an operation is detected in any one of the light switches (S1) 12. |
