# US 2014/0152299 A1 · Encoder

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- Number: US 2014/0152299 A1
- Document ID: US20140152299A1
- Status: Published application
- Kind: A1
- Application number: 14/117,555
- Filed: 2012-08-10
- Published: 2014-06-05
- Earliest claimed: 2011-08-12
- Assignees: Hitachi Metals, Ltd.
- Inventors: Yasuyuki Okada; Yasunori Abe
- Web page: https://patentgrep.com/patent/US20140152299A1

## CPC

- G01R 33/09: Magnetoresistive devices
- G01B 7/003: {for measuring position, not involving coordinate determination (coordinate measuring G01B7/004)}
- G01D 5/24438: {Special design of the sensing element or scale}
- G01D 5/2451: {Incremental encoders (G01D5/2454 takes precedence)}
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)
- G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01D: MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR

## Abstract

A magnetic medium is magnetized in the relative movement direction at a predefined pitch λm and a magnetic sensor includes plural magnetoresistive elements whose electrical resistance value changes depending on a magnetic field at a place where the magnetoresistive element is disposed. A position where the magnetoresistive element is disposed is defined as a reference position and, in addition to the magnetoresistive element of this reference position, the magnetoresistive elements as harmonic reducing patterns are disposed at the following positions, with P(n) defined as the n-th prime: a position offset by λm/(2·P(n)) from the reference position toward at least one side of the relative movement direction, wherein N≧n>1 and N is a natural number satisfying N>3, and a position further offset by λm/(2·P(L+1)) from a position offset by λm/(2·P(L)), wherein 1<L<N.

## Claims

### Claim 1

An encoder including a magnetic medium and a magnetic sensor that is opposed to the magnetic medium with intermediary of a gap and moves relative to the magnetic medium, wherein
the magnetic medium is magnetized in direction of the relative movement at a pitch λm,
the magnetic sensor includes a plurality of magnetoresistive elements whose electrical resistance value changes depending on a magnetic field at a place where the magnetoresistive element is disposed, and
a position where the magnetoresistive element is disposed is defined as a reference position and, in addition to the magnetoresistive element of the reference position, the magnetoresistive elements as harmonic reducing patterns are disposed at following positions, with P(n) defined as an n-th prime, wherein n is a natural number,
a position offset by λm/(2·P(n)) from the reference position toward at least one side of the direction of the relative movement in plan view, wherein N≧n>1 and N is a natural number satisfying N>3, and
a position further offset by λm/(2·P(L+1)) from a position offset by λm/(2·P(L)) from the reference position toward at least the one side of the direction of the relative movement in plan view, wherein P(L) is an L-th prime and L is a natural number satisfying 1<L<N.

### Claim 2 (depends on 1)

The encoder according to claim 1, wherein
the magnetoresistive elements as the harmonic reducing patterns are disposed at following positions,
a position offset by λm/(2·P(2))=λm/6 and a position offset by λm/(2·P(3))=λm/10 from the reference position toward the one side in plan view, and
a position further offset by λm/(2·P(2+1))=λm/10 from the position offset by λm/(2·P(2))=λm/6 from the reference position toward at least the one side of the direction of the relative movement in plan view.

### Claim 3 (depends on 1)

The encoder according to claim 1, wherein
part of the magnetoresistive elements as the harmonic reducing patterns is disposed in a layer different from a layer of the magnetoresistive element of the reference position in a plane opposed to the magnetic medium.

### Claim 4

An encoder including a magnetic medium and a magnetic sensor that is opposed to the magnetic medium with intermediary of a gap and moves relative to the magnetic medium, wherein
the magnetic medium is magnetized in direction of the relative movement at a pitch λm,
the magnetic sensor includes a plurality of magnetoresistive elements whose electrical resistance value changes depending on a magnetic field at a place where the magnetoresistive element is disposed,
a position where the magnetoresistive element is disposed is defined as a reference position and, in addition to the magnetoresistive element of the reference position, the magnetoresistive elements as harmonic reducing patterns are disposed at following positions, with P(n) defined as an n-th prime, wherein n is a natural number,
a position offset by λm/(2·P(n)) from the reference position toward at least one side of the direction of the relative movement in plan view, wherein N≧n>1 and N is a natural number satisfying N>2, and
a position further offset by λm/(2·P(L+1)) from a position offset by λm/(2·P(L)) from the reference position toward at least the one side of the direction of the relative movement in plan view, wherein P(L) is an L-th prime and L is a natural number satisfying 1<L<N, and
x satisfying P(N+1)<x and x≠P(k), wherein k is a natural number satisfying 1<k, is set and the magnetoresistive elements as the harmonic reducing patterns are disposed at following positions,
a position offset by λm/(2x) from the reference position toward at least the one side of the direction of the relative movement in plan view, and
a position further offset by λm/(2x) from the position offset by λm/(2·P(L)), wherein 1<L<N, from the reference position toward at least the one side of the direction of the relative movement in plan view.

### Claim 5 (depends on 4)

The encoder according to claim 4, wherein
the magnetoresistive elements as the harmonic reducing patterns are disposed at following positions,
a position offset by λm/(2·P(2))=λm/6 and a position offset by λm/(2·P(3))=λm/10 from the reference position toward the one side in plan view, and
a position further offset by λm/(2·P(2+1))=λm/10 from the position offset by λm/(2·P(2))=λm/6 from the reference position toward at least the one side of the direction of the relative movement in plan view, and
x satisfying 5<x and x≠P(k), wherein k is a natural number satisfying 1<k, is set and the magnetoresistive elements as the harmonic reducing patterns are disposed at following positions,
a position offset by λm/(2x) from the reference position toward at least the one side of the direction of the relative movement in plan view,
a position further offset by λm/(2x) from the position offset by λm/(2·P(2))=λm/6 from the reference position toward at least the one side of the direction of the relative movement in plan view,
a position further offset by λm/(2x) from the position offset by λm/(2·P(3))=λm/10 from the reference position toward at least the one side of the direction of the relative movement in plan view, and
a position further offset by λm/(2x) from the position offset by λm/(2·P(2))=λm/6 and λm/(2·P(3))=λm/10 from the reference position toward at least the one side of the direction of the relative movement in plan view.

### Claim 6 (depends on 2)

The encoder according to claim 2, wherein
part of the magnetoresistive elements as the harmonic reducing patterns is disposed in a layer different from a layer of the magnetoresistive element of the reference position in a plane opposed to the magnetic medium.