| 摘要 |
PURPOSE:To improve the response speed of an abject detection by detecting the proximity of an object through the decrease in the oscillation output of an oscillation circuit, increasing the gain of the oscillation circuit for a prescribed time by the use of a timer and holding the detection output during that time. CONSTITUTION:The oscillation circuit 1 having a detection coil and to which oscillation gain is varied based on an external signal, a holding circuit 8 holding a comparison output, the timer 5 triggered based on the detection output and increasing the gain of the oscillating circuit 1 for a 1st operating time and a timer 7 triggered by the detection output of the holding circuit 8 for a longer operating time than the operating time above are provided. The oscillation circuit 1 keeps the oscillation at a fine level while the object approaches. The signal is held by the holding circuit 8 during that time and after the oscillating level is increased or the oscillation is stopped depending on the presence of the proximity of the object, the operation of the timer 7 is stopped to stop the output holding. Thus, immediately after the operation of the timer 7 is finished, an object detection signal is outputted.
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