Patent EP0235750A2 successfully refreshed from Google Patents.
EP0235750A2
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EP
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Apparatus for magnetically detecting position or speed of moving body
Assignee: Hitachi Ltd
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Filing: 1987-02-26
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Granted: —
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Expires: 2007-02-26
Abstract
Abstract Magnetic poles are provided continuously with a pitch λ, on the peripheral portion of a drum rotated in accordance with a movement of a moving body. A magnetic sensor is provided in opposition to these poles. The sensor is formed of two magnetoresistive element pairs which are spaced from each other at λ/6, and the two elements in each pair are arranged in positions spaced from each other at λ/2. The two elements in each pair are connected in series to form a bridge circuit. The signals obtained from the nodes of the series-connected elements in the two element pairs are differtially amplified.Owing to this structure, the third harmonic wave components are eliminated, and a signal having no distortion and representative of the position or speed of the moving body can be obtained.
Inventors
- 👤 Tadashi Takahashi
- 👤 Seizi Yamashita
- 👤 Kunio Miyashita
- 👤 Syooichi Kawamata
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 22:11
CPC Classifications
G; G01; G01D; G01D5/00; G01D5/12; G01D5/14; G01D5/142; G01D5/145; G01D5/244; G01D5/24428; G01D5/24433; G01D5/24438; G01D5/24471; G01D5/24476; G01D5/245; G01D5/2451; G01P; G01P3/00; G01P3/42; G01P3/44; G01P3/48; G01P3/481; G01P3/487
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
226 words
An apparatus for magnetically detecting the relative position or speed of moving and stationary bodies, having a magnetic medium provided in either a moving body or a stationary body, a plurality of magnetic poles arranged continuously with a predetermined pitch λ on said magnetic medium, a plurality of MR elements which are provided on the other of said moving body and stationary body so as to be opposed to said magnetic medium, and which is adapted to sense a magnetic field generated by said magnetic poles and thereby cause the electric resistance thereof to vary, and an output circuit connected electrically to said MR elements and adapted to convert the variations of the electric resistance of each MR element into an electric signal which is outputted as a signal representative of the relative position or speed of said moving and stationary bodies, characterized in that said MR elements form a plurality of MR element pairs each of which consists of two MR elements, and the distance between the two MR elements in each MR element pair and the distance between adjacent MR element pairs are determined so that the electric signals based on the variations of electric resistance of said MR elements are generated so as to mutually offset the major higher harmonic components, which are contained in said electric signals, by synthesizing said electric signals.
Claim 2
Independent Claim
226 words
An apparatus for magnetically detecting the relative position or speed of moving and stationary bodies, having a magnetic medium provided in either a moving body or a stationary body, a plurality of magnetic poles arranged continuously with a predetermined pitch λ on said magnetic medium, a plurality of MR elements which are provided on the other of said moving body and stationary body so as to be opposed to said magnetic medium, and which is adapted to sense a magnetic field generated by said magnetic poles and thereby cause the electric resistance thereof to vary, and an output circuit connected electrically to said MR elements and adapted to convert the variations of the electric resistance of each MR element into an electric signal which is outputted as a signal representative of the relative position or speed of said moving and stationary bodies, characterized in that said MR elements form a plurality of MR element pairs each of which consists of two MR elements, and the distance between the two MR elements in each MR element pair and the distance between adjacent MR element pairs are determined so that the electric signals based on the variations of electric resistance of said MR elements are generated so as to mutually offset the major higher harmonic components, which are contained in said electric signals, by synthesizing said electric signals.
Claim 3
Dependent Claim
28 words
An apparatus for magnetically detecting the position or speed of a moving body according to Claim 1, wherein the major higher harmonic component is a third harmonic wave.
Claim 4
Dependent Claim
63 words
An apparatus for magnetically detecting the position or speed of a moving body according to Claim 2, wherein said MR elements constitute k sets of MR element pairs, two MR elements in each pair being arranged in positions . spaced at (m+1/2)X, wherein m is an integer, said MR element pairs being spaced from each other at (n±1/3k)λ, wherein n is an integer.
Claim 5
Dependent Claim
50 words
An apparatus for magnetically detecting the position or speed of a moving body according to Claim 3, wherein said MR elements constitute two MR element pairs, two MR elements in each pair being arranged in positions spaced at λ/2, said MR element pairs being spaced from each other at λ/6.
Claim 6
Dependent Claim
50 words
An apparatus for magnetically detecting the position or speed of a moving body according to Claim 3, wherein said MR elements constitute two MR element pairs, two MR elements in each pair being arranged in positions spaced at 3λ/2, said MR element pairs being spaced from each other at λ/6.
Claim 7
Dependent Claim
50 words
An apparatus for magnetically detecting the position or speed of a moving body according to Claim 3, wherein said MR elements constitute two MR element pairs, two MR elements in each pair being arranged in positions spaced at λ/2, said MR element pairs being spaced from each other at 7A/6.
Claim 8
Dependent Claim
50 words
An apparatus for magnetically detecting the position or speed of a moving body according to Claim 3, wherein said MR elements constitute two MR elements pairs, two MR elements in each pair being arranged in positions spaced at λ/2, said MR element pairs being spaced from each other at 5λ/6.
Claim 9
Dependent Claim
53 words
An apparatus for magnetically detecting the position or speed of a moving body according to Claim 3, wherein said MR elements constitute three MR element pairs, two MR elements in each pair being arranged in positions spaced from each other at λ/2, said MR element pairs being spaced from each other at λ/9.
Claim 10
Dependent Claim
124 words
An apparatus for magnetically detecting the position or speed of a moving body according to Claim 2, wherein said MR elements constitute k sets of MR element pairs, two MR elements in each pair being arranged in positions spaced at (m+½)λ, wherein m is an integer, said MR element pairs being spaced from each other at (n±1/3k)λ, wherein n is an integer, said output circuit being connected electrically to the k sets of said MR element pairs, the k sets of voltages being generated so that the third harmonic components therein have a 2π/k phase, when a power source voltage is applied to this output circuit, the k sets of said voltage being synthesized so as to offset said third harmonic components each other.
Claim 11
Dependent Claim
36 words
An apparatus for magnetically detecting the position or speed of a moving body according to Claim 9, wherein said MR elements constitute two MR element pairs, and said output circuit consists of bridge-connected MR element pairs.
Claim 12
Dependent Claim
88 words
An apparatus for magnetically detecting the position or speed of a moving body according to Claim 10, wherein two MR elements in each MR element pairs are connected in series, said two pairs of series-connected MR elements are parallel-connected to a power source, an electric signal obtained from a node of each of said two pairs of series-connected MR elements is inputted into a differential amplifier, and an output is derived from said differential amplifier as a signal representative of the position or speed of said moving body.
Claim 13
Dependent Claim
64 words
An apparatus for magnetically detecting the position or speed of a moving body according to Claim 11, wherein said MR elements in said two pairs of series-connected MR elements are connected so that the phases of the third harmonic components contained in the electric signals obtained from the nodes thereof becomes opposite to each other, and said electric signals are added to each other.
Claim 14
Dependent Claim
40 words
An apparatus for magnetically detecting the position or speed of a moving body according to Claim 12, wherein said added electric signals are inputted into one terminal of said amplifier with an offsetting voltage applied to the other terminal thereof.
Claim 15
Dependent Claim
139 words
An apparatus for magnetically detecting the position or speed of a moving body according to Claim 9, wherein said MR elements constitute two MR element pairs, said output circuit has a first connection formed by electrically connecting first elements in first and second MR element pairs together so that the third harmonic components contained in the electric signals appearing in the respective elements offset each other and a second connection formed by electrically connecting second elements in said first and second MR element pairs together so that the third harmonic components contained in the electric signals appearing in the respective elements offset each other, and said two connections are series-connected together and further to said power source to obtain said signal representative of the position or speed of said moving body from a node of said two series-connected connections.
References Cited (Backward Citations)
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