EP0151002A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Magnetic detector
Assignee: Panasonic Holdings Corp
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Filing: 1985-01-25
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Granted: —
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Expires: 2005-01-25
Abstract
Abstract A magnetic detector (21) employs a magneto-resistive element (12,13,14) and is intended to detect in a non-contact manner the salients and slots of a member of magnetic material which is the object to be detected. The magneto-resistive element (12, 13, 14) has a non-linear magneto-resistive characteristic and is subjected to a constant DC magnetic field thereby avoiding the non-linear region of such DC magnetic field to permit the use of such elements in the region of good linearity. A DC magnetic field is obtained by means of a simple arrangement wherein the magneto-resistive element (12,13,14) is arranged diagonally in the magnetic field between a permanent magnet (16) and the salients of the magnetic member. Furthermore, two magneto-resistive elements (12, 13, 14) exhibiting phases delayed by π/2 with respect to each other are used in the form of half-bridge so as to improve stability, waveform distorsion and the like of the detected signal with respect to temperature.
Inventors
- 👤 Hiromi Onodera
- 👤 Noriaki Wakabayashi
- 👤 Yasushi Sugizaki
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-03 07:46
CPC Classifications
G; G01; G01P; G01P3/00; G01P3/42; G01P3/44; G01P3/48; G01P3/481; G01P3/488
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
120 words
A magnetic detector for detecting relative movement between a member (20) having teeth-like salients and slots of magnetic material, and a detecting head (21) which comprises a ferromagnetic thin film resistor element (12,13,14) having magnetic anisotropy and a permanent magnet (16) to supply a magnetic field thereto; said ferro-magnetic thin film resistor element (12,13,14) being arranged to respond to a change of the magnetic field in the direction of said relative motion occurring in the magnetic field between said permanent magnet and said teeth-like salients and slots, characterised in that the thin film surface (12) is arranged to be inclined at a constant angle to the surface of the member (20) on which the teeth-like salients and slots are formed.
Claim 2
Dependent Claim
120 words
A magnetic detector for detecting relative movement between a member (20) having teeth-like salients and slots of magnetic material, and a detecting head (21) which comprises a ferromagnetic thin film resistor element (12,13,14) having magnetic anisotropy and a permanent magnet (16) to supply a magnetic field thereto; said ferro-magnetic thin film resistor element (12,13,14) being arranged to respond to a change of the magnetic field in the direction of said relative motion occurring in the magnetic field between said permanent magnet and said teeth-like salients and slots, characterised in that the thin film surface (12) is arranged to be inclined at a constant angle to the surface of the member (20) on which the teeth-like salients and slots are formed.
Claim 3
Dependent Claim
39 words
A magnetic detector according to claim 1, wherein the detecting head (21) comprises two ferro-magnetic thin film resistor elements arranged spaced apart by a distance of (n+1/2).P (n : Integer, P : Pitch of said teeth-like salients and slots).
Claim 4
Dependent Claim
67 words
A magnetic detector according to claim 1 or 2, wherein one end of the or each ferro-magnetic thin film resistor element (27,28) is connected electrically to a reference potential while the other end of the or each element is connected electrically to a constant-current regulated power supply, the output from the detector being taken from the junction between the or each element and the regulated power supply.
Claim 5
Dependent Claim
34 words
A magnetic detector according to claim 1, 2 or 3, wherein the or each ferro-magnetic thin film resistor element (37,38) has a structure including at least one turn within the same thin film surface.
Claim 6
Dependent Claim
51 words
A magnetic detector according to any one of the preceding claims, wherein the detecting head (21) comprises a group of ferromagnetic thin film resistor elements spaced apart by a distance of S.P (S : Integer, P : Pitch of said salients and slots) and the elements are electrically connected in series.
Claim 7
Dependent Claim
48 words
A magnetic detector according to claim 1 or 2, wherein two ferromagnetic thin film resistor elements (27,28) are electrically connected in series between the constant voltatge E1 and the constant voltage E2, and the electric signal is output from the junction between said ferromagnetic thin film resistor elements.
Claim 8
Dependent Claim
119 words
A magnetic detector according to claim 1, wherein the detecting head comprises a first group of elements respectively separated by a distance of S.P (S : Integer, P : poll pitch of member), a second group of elements respectively separated by a distance of S.P, said ferromagnetic thin film resistor elements included in said first group of elements being electrically connected in series respectively; said ferro-magnetic thin film resistor elements included in said second group of elements being electrically connected in series respectively; and said first and second groups of elements being electrically connected in series between a constant voltage E1 and a constant voltage E2 so as to output an electric signal from the point of connection thereof.
Claim 9
Dependent Claim
77 words
A magnetic detector according to any one of the preceding claims, wherein said detector head comprises at least two ferromagnetic thin film resistor elements arranged spaced apart by a distance of (α+ 1/4).P ( X : Integer, P : Pitch of said teeth-like salients slots) and further ferromagnetic thin film resistor elements arranged separately and respectively at spaces of (n+1/2.P (n : Integer) with respect to each of said at least two ferromagnetic thin film resistor elements.
Claim 10
Dependent Claim
149 words
A magnetic detector according to claim 8, wherein the detector head comprises a plurality of ferromagnetic thin film resistor elements for signal detection and a plurality of ferromagnetic thin film resistor elements for compensation; said plurality of ferromagnetic thin film resistor elements for signal detection comprising said at least two ferromagnetic thin film resistor elements spaced apart by (,Z+ 1/4).P ands said further ferromagnetic thin film resistor elements arranged separately and respectively at spaces of (n+1/2).P with respect to each of said at least two ferromagnetic thin film resistor elements; and said plurality of ferromagnetic thin film resistor elements for compensation being arranged at both sides of a substrate on which said elements are provided with said plurality of ferro- magnetic thin film resistor elements for signal detection disposed therebetween while at both ends of respective elements are connected the constant voltage El and the constant voltage E2 electrically,
Claim 11
Dependent Claim
39 words
A magnetic detector according to claim 9, wherein a plurality of ferromagnetic thin film resistor elements for signal detection and a plurality of ferromagnetic thin film resistor elements for compensation employ the same materials and have the same shapes.
Claim 12
Dependent Claim
92 words
A magnetic detector according to any one of claims 1 to 7, wherein said detecting head includes at least m ferromagnetic thin film resistor elements arranged separately and respective at spaces of m.P (m : an integer denoting the number of phase and satisfying m 3; P : Pitch of said teeth-like salients and slots; K : Integer) and further ferromagnetic thin film resistor elements arranged separately and respectively at spaces of (n+l/2).P (n : Integer) with respect to each of said at least m pieces of ferro-magnetic thin film resistor elements.
Claim 13
Dependent Claim
164 words
A magnetic detector according to claim 11, wherein among m pieces of ferromagnetic thin film resistor elements arranged separately at space of , a mth element comprising a mth group fo elements comprising a plurality of ferromagnetic thin film resistor elements arranged separately and respectively at spaces of S.P (S : Integer); the m'th group of elements comprising a plurality of ferromagnetic thin film resistor elements arranged separately and respectively at spaces of S.P, and being arranged at spaces of (n+l/2).P with respect to said mth group of elements; said ferromagnetic thin film resistor elements included in said mth group of elements being respectively electrically connected in series; said ferromagnetic thin film resistor elements included in said m'th group of elements being respectively electrically connected in series; and said mth and m'th groups of elements being electrically connected in series between a constant voltage El and a constant voltage E2 so as to output a mth electric signal from the point of connection thereof.
Claim 14
Dependent Claim
148 words
A magnetic detector according to claim 11 wherein the detecting head comprises a plurality of ferromagnetic thin film resistor elements for signal detection and a plurality of ferromagnetic thin film resistor elements for compensation; said plurality of ferromagnetic thin film resistor elements for signal detection comprising said at least m pieces of ferromagnetic thin film resistor elements arranged separately at spaces of k .P and said ferro-magnetic thin film resistor elements arranged separately and respectively at spaces of (n+1/2).P with respect to each of said at least m pieces of ferro- magnetic thin film resistor elements; and said plurality of ferromagnetic thin film resistor elements for compensation being arranged at both sides of the substrate with said plurality of ferromagnetic thin film resistor elements for signal detection disposed therebetween while at both ends of respective elements are connected the constant voltage El and the constant voltage E2 electrically.
References Cited (Backward Citations)
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