MR position detecting device

[54] MR POSITION DETECTING DEVICE

[75] Inventors: Akihito Nakayama; Satoshi

Sakamoto, both of Tokyo, Japan

[73] Assignee: Research Development Corporation of Japan, Tokyo, Japan

[21] Appl. No.: 805,635

[22] Filed: Dec. 12,1991

[30] Foreign Application Priority Data

Dec. 28, 1990 [JP] Japan 2-416675

Jan. 17, 1991 [JP] Japan 3-015723

[51] Int. CI.' G01R 33/20

[52] U.S. CI 324/318; 324/322

[58] Field of Search 324/300, 301, 302, 307,

324/308, 309, 318, 322; 128/653.5; 335/299

[56] References Cited

U.S. PATENT DOCUMENTS

3,693,072 9/1972 Irons et al 324/301

FOREIGN PATENT DOCUMENTS 0235750 9/1987 European Pat. Off. .

An MR position detecting device according to the present invention comprises a magnet having magnetic poles alternately magnetized at predetermined intervals, a magnetoresistive element having magneto-detectors for a plurality of phases successively disposed a predetermined distance apart, with a pair of the magnetodetectors provided for each phase. The pair of magneto-detectors for each phase change their resistance values in response to the magnetic field of the magnet, are disposed half the formed magnetic pole width, in substance, apart, and are applied with voltage at both ends of a series connection thereof so as to output a signal from the middle point of the connection. A signal processing circuit defects a change in relative position between the magnetoresistive element and magnet on the basis of a signal obtained from the outputs of the pairs of magneto-detectors for the respective phases of the magnetoresistive element therefore, the device may detect position with high resolution and accuracy.

7 Claims, 10 Drawing Sheets

10