Patent US2361344A successfully refreshed from Google Patents.
Patent US4490674A successfully refreshed from Google Patents.
US4490674A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Rotational angle detection device having two magnetoresistive sensing elements
Assignee: NEC Corp
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Filing: 1982-11-18
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Granted: 1984-12-25
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Expires: 2002-11-18
Abstract
Abstract A rotational angle detection device having two magnetoresistive sensing elements positioned at a 45° angle with respect to each other senses the rotary position of a permanent magnet. Sine and cosine waves are applied to first and second bridge circuits respectively incorporating the two sensing elements. The resulting bridge circuit outputs are differentially combined to provide an output whose phase relative to either of the input sine or cosine waves is dependent upon the rotational position of the permanent magnet. The phase difference is detected and the rotational position is calculated therefrom.
Inventors
- 👤 Susumu Ito
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 15:16
CPC Classifications
G; G01; G01D; G01D5/00; G01D5/12; G01D5/14; G01D5/142; G01D5/145; G01D5/244; G01D5/247
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
180 words
A rotational angle detection device comprising: a permanent magnet rotatable in response to the rotation of a rotary shaft for generating a rotating magnetic field; power supplying means for generating sine wave and cosine wave outputs; a magnetic field sensor having said sine wave and cosine wave outputs applied thereto and being responsive to the magnetic field of said permanent magnet for generating an altered sine wave output and an altered cosine wave output having phase angles dependent upon the rotational position of said permanent magnet, said magnetic field sensor comprising at least two magnetoresistive sensing elements formed of ferromagnetic material and positioned to form a 45° angle therebetween; a voltage difference detector for detecting the difference between said altered sine wave and altered cosine wave outputs; a phase difference detector for detecting the phase difference between either of the two outputs of said power supplying means and the output of said voltage difference detector; and a rotational angle calculator for calculating the rotational angle of said rotary shaft on the basis of the output from said phase difference detector.
Claim 2
Dependent Claim
180 words
A rotational angle detection device comprising: a permanent magnet rotatable in response to the rotation of a rotary shaft for generating a rotating magnetic field; power supplying means for generating sine wave and cosine wave outputs; a magnetic field sensor having said sine wave and cosine wave outputs applied thereto and being responsive to the magnetic field of said permanent magnet for generating an altered sine wave output and an altered cosine wave output having phase angles dependent upon the rotational position of said permanent magnet, said magnetic field sensor comprising at least two magnetoresistive sensing elements formed of ferromagnetic material and positioned to form a 45° angle therebetween; a voltage difference detector for detecting the difference between said altered sine wave and altered cosine wave outputs; a phase difference detector for detecting the phase difference between either of the two outputs of said power supplying means and the output of said voltage difference detector; and a rotational angle calculator for calculating the rotational angle of said rotary shaft on the basis of the output from said phase difference detector.
Claim 3
Dependent Claim
103 words
A rotational angle detection device as claimed in claim 1 wherein said sensor comprises a first magnetoresistive sensing element having first to fourth stripe groups formed of ferromagnetic material connected electrically in series so that two adjacent stripe groups among said first to fourth stripe groups form an angle of 90° with each other and a second magnetoresistive sensing element having the same structure as the first sensing element and being disposed over said first sensing element to give the relationship in which two vertically corresponding stripe groups of said first and second sensing elements form an angle of 45° with each other.
Claim 4
Dependent Claim
26 words
A rotational angle detection device as claimed in claim 2 wherein said first and second magnetoresistive sensing elements are arranged on different substrates from each other.
Claim 5
Dependent Claim
20 words
A rotational angle detection device as claimed in claim 3 wherein the central portion of said permanent magnet is perforated.
Claim 6
Dependent Claim
16 words
A rotational angle detection device as claimed in claim 3 wherein said permanent magnet is bar-shaped.
Claim 7
Dependent Claim
31 words
A rotational angle detection device as claimed in claim 2 wherein said first and second magnetoresistive elements are arranged on one substrate, one over the other, with an insulating layer in-between.
Claim 8
Dependent Claim
16 words
A rotational angle detection device as claimed in claim 6 wherein said permanent magnet is bar-shaped.
Claim 9
Dependent Claim
20 words
A rotational angle detection device as claimed in claim 6 wherein the central portion of said permanent magnet is perforated.
Claim 10
Dependent Claim
121 words
A rotational angle detection device as claimed in claim 2 wherein said magnetic field sensor further comprises a first bridge circuit consisting of said first to said fourth stripe groups as the four legs of said first bridge circuit, said sine wave being connected to the input of said first bridge circuit, first differential amplification means connected across the output of said first bridge circuit to provide said altered sine wave, a second bridge circuit incorporating said second sensing element into the same structure as said first bridge circuit, said cosine wave being connected to the input of said second bridge circuit, second differential amplification means connected across the output of said second bridge circuit to provide said altered cosine wave.
Claim 11
Dependent Claim
20 words
A rotational angle detection device as claimed in claim 2 wherein the central portion of said permanent magnet is perforated.
Claim 12
Dependent Claim
16 words
A rotational angle detection device as claimed in claim 2 wherein said permanent magnet is bar-shaped.
Claim 13
Dependent Claim
24 words
A rotational angle detection device as claimed in claim 1 wherein said at least two magnetoresistive sensing elements are arranged on the same substrate.
Claim 14
Dependent Claim
16 words
A rotational angle detection device as claimed in claim 12 wherein said permanent magnet is bar-shaped.
Claim 15
Dependent Claim
20 words
A rotational angle detection device as claimed in claim 12 wherein the central portion of said permanent magnet is perforated.
Claim 16
Dependent Claim
23 words
A rotational angle detection device as claimed in claim 1 wherein said voltage difference detector involves a filter circuit for eliminating undesirable noise.
Claim 17
Dependent Claim
21 words
A rotational angle detection device as claimed in claim 1 wherein said power supplying means involves a digital to analog converter.
Claim 18
Dependent Claim
23 words
A rotational angle detection device as claimed in claim 1 further comprising a rotational angle indicator for indicating the outcome of said calculator.
Claim 19
Dependent Claim
105 words
A rotational angle detection device as claimed in claim 1 wherein said magnetic field sensor comprises first and second magnetoresistive sensing elements, a first bridge circuit including said first sensing element and a second bridge circuit including said second sensing element, said sine wave being applied to the input of said first bridge circuit, first differential amplification means connected across the output of said first bridge circuit to provide said altered sine wave, said cosine wave being applied to the input of said second bridge circuit, said differential amplification means connected across the output of said second bridge circuit to provide said altered cosine wave.
Claim 20
Dependent Claim
32 words
A rotational angle detection device as claimed in claim 1 wherein each of said bridge circuits has four legs, said sensing elements forming one leg of each of said bridge circuits, respectively.
Claim 21
Dependent Claim
16 words
A rotational angle detection device as claimed in claim 1 wherein said permanent magnet is bar-shaped.
Claim 22
Dependent Claim
20 words
A rotational angle detection device as claimed in claim 1 wherein the central portion of said permanent magnet is perforated.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-12-25 | 1988-06-25 | 1988-12-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-12-25 | 1992-06-25 | 1992-12-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-12-25 | 1996-06-25 | 1996-12-25 | $7700.00 | Window Closed / Lapsed |