Abstract: In a liquid level sensor according to the present invention, a first detecting electrode being always in a liquid to be measured, a second detecting electrode which measures a level of the liquid to be measured, and a third detecting electrode being always out of the liquid to be measured are arranged, an operation of charging capacitor 45 for a time being in proportion to a ratio of a length of a part of the second detecting electrode in the liquid to be measured to a total length of the second detecting electrode and an operation of discharging the electric charge of the capacitor for a time being in proportion to a ratio of a length of a part of the second detecting electrode being out of the liquid to be measured to the total length of the second detecting electrode is repeated. With this configuration, the liquid level can be precisely detected without arranging a complex operational device even though a dielectric constant or a temperature of the liquid to be measured changes.

Abstract: A non-contact position sensor includes a magnet, magnetoresistive elements arranged on a line extending in a predetermined direction on a pole surface of the magnet with predetermined intervals, and an object made of magnetic material displaceable in the predetermined direction. The magnetoresistive elements are connected serially between a power supply and a ground. A first magnetoresistive element is connected to the second magnetoresistive element at a first node. A second magnetoresistive element is connected to a third magnetoresistive element at a second node. The object includes a projection and a shaft connected to the projection. The projection can face the first to third magnetoresistive elements. The shaft is located away from the pole surface by a distance longer than a distance between the projection and the pole surface of the magnet.

Abstract: In a liquid level sensor according to the present invention, a first detecting electrode being always in a liquid to be measured, a second detecting electrode which measures a level of the liquid to be measured, and a third detecting electrode being always out of the liquid to be measured are arranged, an operation of charging capacitor 45 for a time being in proportion to a ratio of a length of a part of the second detecting electrode in the liquid to be measured to a total length of the second detecting electrode and an operation of discharging the electric charge of the capacitor for a time being in proportion to a ratio of a length of a part of the second detecting electrode being out of the liquid to be measured to the total length of the second detecting electrode is repeated. With this configuration, the liquid level can be precisely detected without arranging a complex operational device even though a dielectric constant or a temperature of the liquid to be measured changes.

Abstract: A non-contact position sensor includes a magnet, first to third magnetoresistive elements arranged on a line extending in a predetermined direction on a pole surface of the magnet with predetermined intervals, and an object made of magnetic material displaceable in the predetermined direction. The first to third magnetoresistive elements are connected serially between a power supply and a ground. The first magnetoresistive element is connected to the second magnetoresistive element at a first node. The second magnetoresistive element is connected to the third magnetoresistive element at a second node. The object includes a projection and a shaft connected to the projection. The projection can face the first to third magnetoresistive elements. The shaft is located away from the pole surface by a distance longer than a distance between the projection and the pole surface of the magnet. This non-contact position sensor does not include a component having a complicated shape and can be manufactured easily.