Position measuring device having a sensor for sensing the distance between a scanning unit and a scale

A method for measuring the relative position of a first object with respect to a second object, comprising the steps of:

• providing a scale-on the first object, the scale having a periodic graduation in the form of a magnetized pattern;
• providing a scanner unit on the second object for scanning the scale;
• providing a sensor disposed on the scanning unit, wherein the sensor detects the distance between the scanning unit and the graduation and generates a correction signal dependent upon the distance detected, wherein the sensor is formed by a plurality of magnetoresistive elements which are placed directly opposite the periodic graduation and scan the periodic graduation wherein the magnetoresistive elements of the sensor are distributed three-dimensionally relative to the scale and are electrically wired together so that a largely unmodulated correction signal appears at the output of the sensor unit;
• scanning the scale with the scanning unit;
• generating position-dependent scanning signals using the plurality of magnetoresistive elements provided on the scanning unit, wherein the scanning signals are dependent on the instantaneous position of the scale in the measurement direction;
• generating the correction signal using a sensor formed by the magnetoresistive elements, the correction signal being dependent upon the distance between the scanning unit and the scale;
• and
• correcting the position-dependent scanning signal with the correction signal.

A position measuring device for measuring the relative position for a first object with respect to a second object, comprising:

• a scale located on the first object having a periodic graduation in the form of a magnetized pattern;
• a scanning unit located on the second object for scanning the graduation located on the first object;
• a plurality of magnetoresistive elements disposed on the scanning unit, wherein the elements are exposed to the graduation to generate position-dependent scanning signals wherein the scanning signals are dependent on the instantaneous position of the scale in the measurement direction;
• and
• a sensor disposed on the scanning unit, wherein the sensor detects the distance between the scanning unit and the graduation and generates a correction signal dependent upon the distance detected wherein the sensor is formed by the same magnetoresistive elements used to generate the position-dependent scanning signals and the magnetoresistive elements of the sensor are distributed three-dimensionally relative to the scale and are electrically wired together so that a largely unmodulated correction signal appears at the output of the sensor unit.

A position measuring device for measuring the relative position of a first object with respect to a second object, comprising:

• a scale located on the first object having a periodic graduation in the form of a magnetized pattern;
• a scanning unit located on the second object for scanning the graduation located on the first object;
• a plurality of magneto-resistive elements disposed on the scanning unit, wherein the elements are exposed to the periodic graduation to generate position-dependent scanning signals wherein the scanning signals are dependent on the instantaneous position of the scale in the measurement direction;
• and
• a sensor disposed on the scanning unit, wherein the sensor detects the distance between the scanning unit and the graduation and generates a correction signal dependent upon the distance detected wherein the sensor includes said plurality of magnetoresistive elements, which are placed directly opposite of the periodic graduation and scan this periodic graduation and the correction signal largely unmodulated by the periodic graduation is present at the output of the sensor, wherein the plurality of magneto-resistive elements includes a plurality of magneto-resistive elements connected to form a parallel circuit and the correction signal is taken at the output of the parallel circuit, wherein the magneto-resistive elements for detecting the spacing are disposed within one division period and the plurality of magneto-resistive elements are connected to make a plurality of full bridge circuits connected in parallel wherein the full bridge circuits generate phase-displaced signals and the correction signal is taken at the output of the parallel circuit.