| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a keyboard device of an electronic musical instrument, which prevents an accident such as damage of the device and fire even if a power supply circuit supplying power breaks down and excess voltage is outputted from the power supply circuit. <P>SOLUTION: The device is provided with a relay positioned between the power supply circuit supplying power and a solenoid coil and is provided with an excess voltage application preventing circuit monitoring application of excess voltage exceeding prescribed voltage to the solenoid coil and changing the relay to an interruption state by application of excess voltage to the solenoid coil. When the power supply circuit breaks down and excess voltage is outputted from the power supply circuit, the excess voltage application preventing circuit interrupts the relay and stops supply of power to the solenoid coil. <P>COPYRIGHT: (C)2004,JPO |
