Abstract: In a position measuring device in which data, which requires buffering, may be held without accommodating a high-capacitance capacitor in the inside of the encoder, a backup current source may be exchanged while the circuits required for the operating capability state remain operable. In addition, current usage during the buffering time may be held low, and the service life of the backup current source may be extended, so that the demand for maintenance may be reduced. The position measuring device may include an encoder main part, arranged to measure the extent of the shift in position of an object to be measured, and a backup current source arranged to supply backup current when main current source, that supplies encoder main part with current, is interrupted. Outside of the encoder main part, an auxiliary current source is provided which, during the exchange of a main battery of the backup current source, undertakes supplying backup current in place of this main battery.

Abstract: In a position measuring device in which data, which requires buffering, may be held without accommodating a high-capacitance capacitor in the inside of the encoder, a backup current source may be exchanged while the circuits required for the operating capability state remain operable. In addition, current usage during the buffering time may be held low, and the service life of the backup current source may be extended, so that the demand for maintenance may be reduced. The position measuring device may include an encoder main part, arranged to measure the extent of the shift in position of an object to be measured, and a backup current source arranged to supply backup current when main current source, that supplies encoder main part with current, is interrupted. Outside of the encoder main part, an auxiliary current source is provided which, during the exchange of a main battery of the backup current source, undertakes supplying backup current in place of this main battery.

Abstract: A rotation number data detection-type encoder may reduce costs and power consumption by reducing the number of expensive magnetic detection elements. An encoder main body for measuring the displacement magnitude of a measured object includes a rotation detection portion for counting n rotations (an integer not including n=0) of the measured object and a displacement magnitude detection portion for measuring the displacement magnitude of the measured object. The rotation detection portion has a magnetic detection portion for detecting the magnetic change in a magnetic rotating body and an optical detection portion for detecting a slit in an encoding plate.