Sony Precision Technology Inc.

Tadahiko Shimano

Masaaki Kusumi

Takamoto Yoshioka

Jun Iijima

A magneto-resistive effect sensor capable of outputting a sufficient output of optimum characteristics even if a magnetized surface of a magnetized material is curved, arcuately- or polygonally-shaped. On the magneto-resistive effect sensor,plural magnetically sensitive portions,to,of the same shape are formed and arrayed parallel to one another, while being electrically connected in series to permit the current i to flow through the electrically connected magnetically sensitive portions. The magnetically sensitive portion,is made up of a mid portion,having a width w,and ends having a width w,A signal magnetic field of different strengths is applied from the magnetized material along the current flowing direction. The widths w,and w,differ with the strengths of the applied signal magnetic field and are of a ratio such that w,:w,&equals;2:3. The strength of the signal magnetic field is high to give high resistance in a narrow-width area of the magnetically sensitive portion,while being low to give low resistance in a broad-width portion of the magnetically sensitive portion,such that the magneto-resistive effect sensor in its entirety can develop a sufficient output with an optimum S/N ratio.

Position detecting device using varying width magneto-resistive effect sensor

The present invention provides a position detection apparatus capable of reducing the bending moment in the longitudinal direction of a recording medium and being fixed to a machine tool without deforming the main body or the recording medium, thus enabling to obtain a high detection accuracy. The position detection apparatus detects a relative movement position between the reference block 4 and the movable block which move relative to each other along straight line. A round bar-shaped recording medium 12 is provided inside a frame 11 of a main body 2. The frame 11 is fixed to the reference block 4 with a fixing member 55 having an abutment surface for the frame 11 which abutment surface has a curvature only in a direction parallel to the longitudinal direction of the recording medium.

Position detection apparatus

The present invention provides a position detection apparatus capable of suppressing a crosstalk between a scale signal and an origin signal and detecting a position with a high accuracy. A recording medium 12 of a round bar shape has a magnetic signal alternately reversing the polarity at a predetermined recording wavelength .lambda..sub.1 and recorded as a scale signal in the longitudinal direction of the recording medium 12. This scale signal is recorded over the entire outer circumferential surface of the recording medium 12 and almost over the entire length of the recording medium 12. Moreover, the recording medium 12 has a one-wavelength origin signal of recording wavelength .lambda..sub.2 recorded at least at one position over the scale signal. The recording wavelength .lambda..sub.2 of this origin signal is longer than the recording wavelength .lambda..sub.1 of the scale signal. The origin signal is recorded at a part of the outer circumference. An origin signal detection head is arranged to face the origin signal whereas a scale signal detection head is arranged opposite to the origin signal detection head so as to sandwich the recording medium 12.

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Kanagawa, Japan

Tadahiko Shimano