Abstract: A displacement sensor includes a coil, an inverter electrically connected to the coil, the inverter being configured to generate an oscillation signal, a reducer electrically connected between the coil and an output terminal of the inverter, the reducer being configured to reduce the strength of the oscillation signal, and a frequency detector electrically connected to the inverter, the frequency detector being configured to detect an oscillation frequency of an oscillator circuit in response to a distance between a measurement target and the coil, the oscillator circuit including the coil, the inverter, and the reducer and having an oscillation frequency of 30 MHz or higher.

Abstract: An integrated circuit for measuring the distance houses an oscillator in a package. Further, a plane inductor is provided on the surface of the package housing the oscillator. The plane inductor is connected to the oscillator so as to specify a frequency of the oscillator. If conductive material approaches the surface of the package, the frequency of the oscillator is varied by means of the plane inductor. The approaching distance of the conductive material is detected by detecting the frequency of the oscillator. The conductive material is mostly metal, however, the integrated circuit for measuring the distance can measure the approaching distance of non-metal conductive material such as conductive liquid.