JPS59100816A - Magnetoelectric converter - Google Patents

Abstract

PURPOSE:To obtain a magnetoelectric converter generating a sufficient outputs in spite of narrow recording wavelength by arranging a comb-like magnetic thin film resistor forming ferromagnetic materials in a prescribed direction to a magnetic field and fixing the pattern width of the thin film resistor on a prescribed value. CONSTITUTION:A repeating magnetic signal with wavelength lambda which is recorded in a turn table 11 forms ferromagnetic materials C, D arranged so that the magnetic field due to the magneic signal meets with the flowing current direction at right angles and the interval is detected by the comb-like magnetic thin film resistor with lambda/4 wavelength. Since the pattern width of the thin film resistor is fixed on 1.5mum or less, the changing ratio of resistance value is increased, the magnetic force line due to a signal 12 is made incident to the thin film resistor without leakage by the relative arrangement between the thin film resistor and the signal 12 and gap length due to the thin film resistor is made minute. Conseuqntly, the magnetoelectric converter generating sufficient outputs in spite of narrow recording wavelength is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetoelectric transducer used for detecting the turning angle of a rotational speed control device such as a capstan motor of a VTR.

Conventional 174 configuration and its problems A conventional magnetoelectric transducer ffi will be explained with reference to FIGS. 1 and 2. Repeated magnetic signal (2) in which a plurality of magnetic poles are arranged and recorded in the phase of the turntable (1)
The ferromagnetic material Q■ of the magnetoelectric transducer is arranged to face the plane so that it is substantially perpendicular to the plane of
41335). The ferromagnetic material 0 is formed by depositing a ferromagnetic material such as nickel cobalt having an anisotropic effect on magnetoresistance on the entire surface of the substrate (3), and then etching it to form a comb-like pattern. It is something. The distance between the ferromagnetic materials Q2 is one λ with respect to the recording wavelength λ of the adjacent repeated magnetic signals (2). Saturation magnetize a ferromagnetic material 4
- A magnetic field H strong enough to
is carved in the current direction of the ferromagnetic material O) on the plane formed by the ferromagnetic material Q■ and added at an angle θ, the ferromagnetic material Q@l
Each electrical resistance eA.

Pwffi changes, and the change is expressed by the following equation using the angle θ.

ea=91- sin"θ0P li cos"tl-
−−−−■0B=P> cos”0+p1.Bin
"a・------■ Since the voltage of the output terminal (5) 7 and the ferromagnetic material Q■ are connected in series, if the electrical pressure applied to the terminal (4aX4b) is vo, it can be expressed by the following formula. It will be done.

(However, Δp = p tt - pl) In such a conventional magnetoelectric conversion device, as shown in FIG.
Gap (G,) to the outer peripheral surface of the element for repeated magnetic signals (2), gap due to the protective film protecting the element (G,), and substrate supporting the ferromagnetic material Q■ The gap (G, ) is the sum of the gap (G, ) between the end face and the ferromagnetic material (A) 03 and the magnetically sensitive width (G, ) of this ferromagnetic material QeO.
In contrast to o), magnetic signal (2) requires a sufficiently strong magnetic field. By the way, since VTR capstan motors require highly accurate rotational speed control, turn tape/l
/(1) magnetic signal 9(2) recording wavelength λ is α628J1
The recording wavelength is as narrow as 11. For detection at such a narrow recording wavelength, the above-mentioned conventional magnetoelectric transducers have the disadvantage that a sufficient magnetic field cannot be applied to the wide gap ferromagnetic material, making it impossible to obtain sufficient output. .

OBJECTS OF THE INVENTION The present invention solves the above-mentioned conventional drawbacks, and aims to provide a magnetoelectric transducer that can obtain sufficient output even at a narrow recording wavelength.

Structure of the Invention In order to achieve the above object, the magnetoelectric transducer of the present invention repeats a pair of comb-shaped magnetic thin film resistors having a shape anisotropy with a pattern width of 15 μm or less to produce a magnetic signal with a recording wavelength λ. A magnetoelectric transducer is formed on an insulating substrate with an interval of 7λ, and the magnetoelectric transducer is arranged such that the pair of comb-shaped magnetic thin film resistors face the magnetic interface of the reciprocating magnetic signal in a plane, and The arrangement is such that the direction of current flowing through the comb-shaped magnetic thin film resistor is always approximately perpendicular to the magnetic field from the comb-shaped magnetic signal source.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 5 and M6, (1υ is a turn tape μ, and four magnetoelectric transducers Q4 are arranged so as to face the repeated magnetic signal 021 magnetically recorded in a local part of this turn tape /l/(Ill). 4. The pattern of this magnetoelectric transducer H is the same 7-groove pattern as the conventional element shown in FIG. They are arranged at intervals of 7λ.The pattern width W of the ferromagnetic material 00 is narrower than that of the conventional pattern, and is approximately 15μ or less.

Next, the operation will be explained. The magnetic field that acts on the ferromagnetic material (Q In I), the resistance value does not change when the applied magnetic field is perpendicular to the film surface, but the resistance value changes depending on the strength of the magnetic field that is perpendicular to the current in the direction horizontal to the film surface.Turn tape A/ (+1) The resistance values PC and pD of the ferromagnetic material 0O when rotated are respectively expressed by the following equations.

P c=Oo−Δpsin”a −=■P D”Oo−
Δpcos”α・・・・・・■ Therefore, the terminal (t4
a) Voltage V at (t4b). When the power supply of terminal (16) is connected, the output voltage α of terminal (16) is expressed by the following formula.

Next, a more specific embodiment will be described with reference to FIG. A metal film of 80% nickel/l/20% cobalt is vapor-deposited on a glass substrate Q6 to a thickness of 100 OA, and this is etched to form a ferromagnetic material Oa.
Qη was formed. ferromagnetic material oO /< turn width ω is 10
μ-cho zigzag fold back once, total length of sensing part 6cm
%p=IKΩ, Δe=45Ω, saturation magnetic field Hk=16
0 Gauss and a magnetoelectric transducer (Ia) with a protective layer 071 thickness of 30 μm, a turn tape A/ (II
) with a gap α2, the power supply voltage DC1
An output of 10100I was obtained at 2V. On the other hand, with the magnetoelectric transducer (la) in the same position as before, turn tape yv
(++) and measured its output, only a small output of less than %IIIV was obtained.

In addition, by changing the pattern width of the ferromagnetic material 00, the rate of change in resistance against a magnetic field in the same direction as the current direction and a magnetic field in a direction perpendicular to the current direction is as shown in Figures 8 and 9, respectively. It was found that there is a large change in the thickness after 15 μm. In the conventional arrangement, the resistance value of the ferromagnetic material changes in both magnetic field directions, which are the same direction as the current direction and the direction perpendicular to the current direction, but in the above arrangement where there is no magnetic field in the same direction as the current direction, The resistance change of that component cannot be used. However, as shown in FIG. 9, when the pattern width ω is narrowed, shape anisotropy appears in which the rate of change in resistance value with respect to the magnetic field in the direction perpendicular to the current direction increases.
The ferromagnetic material OO with a transducer element O was constructed with a narrow pattern of 15 μm or less in width.

In this way, conventionally the gap (G8) (G
2) CG,) (G,) is required, and the gap for each is α2111! , α, α2, and α5 are required, so the total gap is Llmlml, and the loss due to the gap is large, and the magnetic signal recording wavelength λ is [L6
While almost no output is produced for the magnetic field of a narrow magnetic signal (2) such as 28f11, in the above configuration, the distance between the magnetic signal (12) and the ferromagnetic material 00 is the same as that of the protective film ( lη and the repeated magnetic signal (just the sum of the gap for 121) can be placed close to the signal source, so a large output can be obtained.In addition, conventionally only the magnetic flux (b) in Fig. It is not used, and the magnetoelectric conversion element (
3) rt is not used for the magnetic flux passing near the area of 3), so the utilization efficiency rate is poor and the output is small.In contrast, in the above configuration, the magnetic flux is repeatedly faced to the magnetic signal H in a plane. Because it has a magnetic flux, it can sense most of the magnetic flux, and its utilization efficiency is high, resulting in high output. Furthermore, since the pattern width of the ferromagnetic material 00 is set to less than 15 μm, the directionality of magnetic field sensitivity is good and a high output voltage can be obtained.

As described in detail, according to the present invention, a sufficiently large output can be obtained even with a narrow recording wavelength, and highly accurate rotation angle detection can be realized.

[Brief explanation of drawings]

Fig. 1 is a schematic perspective view of the conventional device, Fig. 2 is an explanatory diagram of the operating principle of the conventional device, Fig. 3 is an explanatory diagram of the pattern and gear of the magnetoelectric transducer in the conventional device, and Fig. 4 is an explanatory diagram of the conventional device. FIG. 5 is a schematic perspective view of a magneto-electric converter according to an embodiment of the present invention, FIG. 6 is an explanatory diagram of the operating principle of the magneto-electric converter, and FIG. 7 is a circuit diagram. Magnetic H
Fig. 8 is an explanatory diagram of the arrangement relationship between the magnetoelectric conversion element and the repetitive magnetic signal source in the converter; Figure 9 is an explanatory diagram of the resistance change rate due to a magnetic field in the direction perpendicular to the current direction when changing the turn width of a ferromagnetic material. ,θ
Q...Glass substrate (insulating substrate), Oa...Ferromagnetic material (comb-shaped magnetic thin film resistor) Fig. 1? Figure 2 Figure 3 Figure 5 Figure 7 q Figure 8 l Figure 6 Figure 8 [Z 1 [X 80 turns Nakadake]

Claims (1)

[Claims] t A pair of comb-shaped magnetic thin film resistors having shape anisotropy with a pattern width of 15 μm or less is repeatedly used to record the magnetic signal at the recording wavelength λ.
A magnetoelectric transducer formed on an insulating substrate is provided with an interval of 1/4λ between the magnetoelectric transducer and the -
The comb-shaped magnetic thin film resistors in the array face the magnetic interface of the comb-shaped magnetic signal in a plane, and the direction of current flowing through the comb-shaped magnetic thin-film resistors is always substantially perpendicular to the magnetic field from the comb-shaped magnetic signal source. Magnetoelectric conversion device placed in.