| 摘要 |
A plurality of sensitive high-frequency proximity switches are provided in the bumper of a car and obstacles can be accurately identified. The electronic car bumper includes: a plurality of sensor portions each having sensor plates, first loading coils, and a divided capacitor, and a reference resonance circuit having a reference capacitor, a second loading coil and a divided capacitor. An oscillator drives each of the sensor portions and the reference resonance circuit through switching devices, and a detector detects an output of the oscillator. A discrimination portion discriminates an output of the detector and provides a discriminated signal to an output portion corresponding to the sensors and the reference resonance circuit. A synchronous device switches the switching device and the discriminator portion in synchronization. A direct current amplifier has an output which is adjusted to a point at zero as a reference voltage for the output corresponding to the reference resonance circuit, and a comparator is adjusted to a threshold reference according to the reference voltage.
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