| 摘要 |
<P>PROBLEM TO BE SOLVED: To finely adjust sensitivity with a small number of components. <P>SOLUTION: An operation part 22 is provided for this proximity sensor comprising a detection part including an oscillation circuit 10 and an amplifier part 2 having a function for detecting a metal body by using oscillation amplitude of the oscillation circuit 10. When an operation for setting an adjustment value (sensitivity adjustment value) for adjusting sensitivity is executed in the operation part 22 in a setting mode, a CPU 20 generates a sensitivity adjustment signal of a digital quantity showing the sensitivity adjustment value to output it to a D/A converter 25. The sensitivity adjustment signal subjected to analog conversion by the D/A converter 25 is provided to a feedback circuit 13 through a voltage adjustment circuit 26. Since the feedback circuit 13 is so designed as to change a feedback current value by an applied voltage, a current of a value in response to the value of the sensitivity adjustment signal is fed back to a resonance circuit 11 and the oscillation amplitude is controlled. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
