| 摘要 |
<p>PURPOSE:To surely detect the fact that car audio equipment is removed from a vehicle by operating a security circuit by judging that no antenna plug exists when ON or OFF of power supply is detected. CONSTITUTION:The antenna plug 12 is inserted to an antenna jack 11 in a stationary state where the audio equipment is set on the vehicle, and a switch 13 is turned on. In such a case, when the power supply from a battery 2 is cut off, power supply disconnection is detected by a signal level from an inverter 9. The disconnection of the power supply due to either the exchange or exhaustion of the battery is detected, and the disconnection of the power supply can be detected since the plug 12 is present within the jack 11 and the audio equipment is set correctly on the vehicle. At this time, the security circuit is operated, and when ON of the power source is detected, the security circuit is stopped to operate. Thereby, it is possible to surely detect the fact that the audio equipment is removed from the vehicle which eliminates the unnecessary operation of the security circuit.</p> |
