| 摘要 |
The present invention includes a detection coil (4) in a self-oscillation circuit (10) in a position detection device. The oscillation frequency of the self-oscillation circuit (10), which is configured from the coil (4) and a capacitor, is set to a high frequency band (for example, around 1 MHz or higher). A target section (3) of which the relative position with respect to the coil (4) changes in accordance with the displacement of a detection subject comprises a magnetically responsive member configured in a manner so as to change the inductance of the coil (4) in accordance with the relative position. A rectifier circuit (21) extracts the amplitude level of the oscillation output signal of the self-oscillation circuit (10) and outputs the result as position data of the detection subject. As an example, a plurality of self-oscillation circuits (10a, 10b) are provided. As a separate example, a single self-oscillation circuit (10) forms a plurality of series circuits by, for every pair of a plurality of coil pairs, connecting in series the two coils (4a, 4b) configuring the coil pair, and includes the result of connecting the series circuits in parallel as an inductor element for self-oscillation. |
