| 摘要 |
PURPOSE:To prevent vibrations at opening/closing door from being outputted as noise, by providing a muting circuit which mutes sound signals when a door motor operates by utilizing the output of a door motor driving circuit. CONSTITUTION:If a door opening/closing switch (S)14 is turned on in the direction of a contact 14a when a door is closed, a transistor (TR)13 is turned on and a motor 11 makes normal rotation and, as a result, the door is opened. Simultaneously, another TR17 is also turned on and sound signals from an input terminal 19 are muted. When the door is completely opened, a limit S16 is turned on and the TR is turned off, and then, the motor 11 is stopped. At the same time, the TR17 is also turned off and the muting is released. If the S14 is turned on in the direction of another contact 14b when the door is opened, a TR12 is turned on and the motor 11 is rotated in the opposite direction, and then, the door is closed. Simultaneously, the TR17 is turned on and the muting is started. When the door is completely closed, the S15 is turned on and the TR12 is turned off, and then, the motor 11 is stopped. At the same time, the TR17 is also turned off and the muting is released. Therefore, noise can be prevented. |
