JPH02186285A - Magnetic bearing detector - Google Patents

Abstract

PURPOSE:To achieve a smaller size eliminating assembling at a sensor section by providing a permanent magnet which is so arranged that a specified biased magnetic field is applied roughly at 45 deg. to the length of respective magnetoresistance elements of first and second half bridge circuits. CONSTITUTION:First and second half bridge circuits 21 and 31 made up of fixed resistance elements 3 and 8 comprising a resistor thin film and magnetoresistance elements 2 and 7 comprising a fine line-shaped ferromagnetic thin film connected in series on an insulation substrate 1 are formed so as to be at the right angle between lengths of the magnetoresistance elements 2 and 7 thereof. A permanent magnet 12 is fixed on the underside of the insulation substrate 1 so that a specified biased magnetic field 22 is applied roughly at 45 deg. to the length of the first magnetoresistance element 2 and roughly at 45 deg. to the length of the second magnetoresistance element 7.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a magnetic orientation detection device used to detect earth's magnetism and measure orientation.

[Prior art]

2. Description of the Related Art A magnetic modulation type sensor called a fluxgate is conventionally known as a device that detects earth's magnetism and measures magnetic direction. This flux gate is constructed by winding a primary coil around a ring-shaped core, and further winding a secondary coil so as to intersect with each other at right angles to each other on the diameter line of the core.

[Problem to be solved by the invention]

The magnetic direction detection device using the above flux gate is
It is necessary to arrange the secondary coils of the flux gate so that they are exactly perpendicular to each other, and the assembly structure thereof is complicated and relatively large. Furthermore, the circuit section for driving and controlling this magnetic orientation detecting device requires a highly accurate oscillation circuit, which makes it large, complex, and expensive. The present invention has been made to solve the above problems, and its purpose is to:
The object of the present invention is to provide an inexpensive and highly accurate magnetic orientation detecting device that is formed in the same manner as the manufacturing process of an IC, eliminates the conventional assembly, is miniaturized, and has a circuit section excluding an oscillation circuit.

[Means to solve the problem]

The structure of the invention for solving the above problems is such that a fixed resistance element made of a resistive thin film and a magnetoresistive element made of a thin wire-shaped ferromagnetic thin film are connected in series on an insulating substrate. a half-bridge circuit, a fixed resistance element made of a resistor thin film on the insulating substrate, and a thin wire-shaped ferromagnetic thin film whose longitudinal direction is perpendicular to the longitudinal direction of the magnetoresistive element of the first half-bridge circuit. a second half-bridge circuit formed by connecting a magnetoresistive element in series;
Arranged so that a predetermined bias magnetic field is applied in a direction of approximately 45 degrees with respect to the longitudinal direction of the magnetoresistive element of the first half-bridge circuit and the longitudinal direction of the magnetoresistive element of the second half-bridge circuit. It is characterized by being equipped with a permanent magnet.

[Effect]

A first half-bridge circuit and a second half-bridge circuit are formed by connecting in series a fixed resistance element made of a resistive thin film and a magnetoresistive element made of a thin wire-shaped ferromagnetic thin film on an insulating substrate. The longitudinal directions of these magnetoresistive elements are formed at right angles. The permanent magnets are arranged so that a predetermined bias magnetic field is applied to each of the permanent magnets in a direction of about 45 degrees with respect to the longitudinal direction of the magnetoresistive elements. Therefore, when an external magnetic field acts on the magnetic orientation detection device having the above configuration, a signal having a phase difference of 90 degrees with respect to the direction of the external magnetic field is generated from the output terminals of the first half-bridge circuit and the second half-bridge circuit. By obtaining this, the direction of the external magnetic field is measured.

【Example】

The present invention will be described below based on specific examples. FIG. 1 shows the configuration of the apparatus of this embodiment. First, a ferromagnetic thin film and a resistive thin film are deposited under an insulating substrate 1, and these ferromagnetic thin films and resistive thin films are etched to form a thin wire-shaped first magnetoresistive element 2 and a first fixed resistor. Element 3 is formed. Then, a conductive metal such as AI is connected to the first magnetoresistive element 2 and the first fixed resistance element 3 so that the first magnetoresistive element 2 and the first fixed resistance element 3 are electrically connected in series. Electrode 4 is deposited on top and etched.
゜5.6 is formed. A first half-bridge circuit 21 is formed by the first magnetoresistive element 2 and the first fixed resistance element 3, using these electrodes 4, 5.6 as a power supply, a ground, and a first output terminal, respectively. Next, on the insulating substrate 1, by the same manufacturing method as described above, a thin wire-shaped second magnetoresistive element 7 and a second A fixed resistance element 8 is formed. Next, using the electrodes 9, 10, and 11 formed in the same manner as described above as power supply, ground, and second output terminals, a second half is formed by a second magnetoresistive element 7 and a second fixed resistance element 8. A bridge circuit 31 is formed. And approximately - with respect to the longitudinal direction of the first magnetoresistive element 2
45 degrees, approximately 4 degrees with respect to the longitudinal direction of the second magnetoresistive element 7
A permanent magnet 12 is fixed under the insulating substrate 1 so that a predetermined bias magnetic field 22 is applied in a direction of 5 degrees. Generally, when a parallel magnetic field is applied to the surface of a magnetoresistive element made of a ferromagnetic Ps film, its internal resistance is maximum when the current and magnetic field directions are parallel, and minimum when the current and magnetic field directions are orthogonal. This results in nonlinear characteristics as shown in Figure 4. In the magnetic orientation detection device having the above configuration, a predetermined bias magnetic field 22 of the permanent magnet 12 causes a negative bias magnetic field (-Horr ) is applied, and a positive bias magnetic field (H, , , ) is applied to the second magnetoresistive element 7 of the second half-bridge circuit 31 in the lateral direction. Then, as shown in FIG. 4, the bias magnetic field (
The strength of H6, , or -H, , ) is approximately the center value of the range in which the resistance value changes approximately linearly due to fluctuations in the magnetic field, that is, the strength of the magnetic field and the resistance value are in a proportional relationship. It is set to take the value of Ro, which is approximately the center value of the range that can be considered as.Therefore, by this bias magnetic field, the first
The first magnetoresistive element 2 of the half-bridge circuit 21 and the second magnetoresistive element 7 of the second half-bridge circuit 31
The internal resistance of is Ro if no external magnetic field exists, and the resistance value of the fixed resistance element 3.8 is also R for convenience. The same value as . Next, its effect will be explained. FIG. 2 is a circuit diagram showing the first half-bridge circuit 21, in which the resistance value of the first magnetoresistive element 2 is RI, the first
The resistance value of the fixed resistance element 3 is assumed to be R7. Then, as shown in FIG. 1, +
The angle at which the external magnetic field H acts is 0 degrees, and the rotation angle when the external magnetic field H rotates clockwise is θ. Find Vl as the output voltage of the first output terminal 6. First, R8 is a function whose resistance value changes depending on the component H in the X direction of the external magnetic field H, so let R, = g(H), and use the proportional coefficient Let k be g(H) = g(-H, rr-H
, ) = g (-H, rr) - k - H, however, H, < l - H0re 1 Here, as mentioned above, since g (-Horr) = Ra is set, 1, ', R ,=Ra− to −H,・−・・−1・
(1) Also, R2 is R,=R,-----(2) as described above. Next, if the power supply voltage between the power supply electrode 4 and the ground electrode 5 is E, the output voltage Vl of the first output terminal 6 is v, = (Ri/(R, +R2)l E ・−・°
... is expressed as °・(3). Therefore, in equation (3), (1
)2 and C) Formula RR; is substituted, V += (Ro/(R6-k −H, +Ro))
E= (R, /(2Ro-k −H,))
E= (1/ (2-(k/R,)H,)) Ewhere, t=(k/Ro)H. Then, equation (4) is V, = (1/(2-t))E, where f(t)=1/(2-t), and substituting equation (7) into equation (6). Then, V,=f(
t)・E Here, if t<1, equation (8) becomes V,=(f
(0)+(1/2+)f' (0)・t+(1,/
3! )f' (0)・t2+・・・・・・）E
It can be expressed as (9), and by differentiating equation (7), f
'(t)=1/(2-t)'',', f'(
()) = 1/4 −・・ ・−・−・ 00
The third and subsequent terms on the right-hand side of equation (9) are sufficiently small and can be ignored, and equation (9) and equation (7)

[Substituting the value when = 0 and the value of formula 01, V, = (<1/2) + (1/2H1, /4)t)
E= ((1/2)+(1/8)t)
E ---Q+) Substituting equation (5) into equation 09 above, VI= ((1/2)+(1/8)(k/R,)H,)
E= f(1/2>+(k/8Ra)H#)E −
OZ, °, H, = (8R, /k) ((V, /E) - (1
/2)) -(131Here, since H,=H-sinθ, the equation for 0 is V+= ((1/2)+(k/8
Ra) H-sin θ) E-04). Similarly, the output voltage V2 of the second output terminal II of the second half-bridge circuit 31 is the X-direction component H of the external magnetic field H.
Since the resistance value changes due to , v, = ((1/2)
+(k/8Ro)H,) E ---...-Q9,-,
H, = (8R, /k) ((V, /E) - (1/2)3
'...00 Here, since Hy=H-cosθ,
Equation 09 is V == ((1/2 >+(k /8 R
0)H-cosθ)E-Q'l), so the output voltage V of the first output terminal 6 of the first half-bridge circuit 21 and the second output terminal 11 of the second half-bridge circuit 31 The output voltage V, is 90 as shown in FIG.
The result is a signal with a phase difference of degrees. Therefore, from the value of the output voltage V1 indicating the component H8 in the X direction of the external magnetic field H corresponding to the rotation angle θ, and the value of the output voltage V indicating the component Hy in the X direction of the external magnetic field H corresponding to the rotation angle θ, The azimuth angle θ of the external magnetic field H is expressed as O! It is obtained by substituting formula 1 and formula 00. jan-'θ=H, /H. Further, the magnitude of the external magnetic field H can be obtained by substituting the 0 formula and the 00 formula into the following formula. I Hl =r(H,'+)(y2) Also, the X-direction component H8 and the X-direction component H7 of the external magnetic field H
If a full bridge circuit is used to detect the output voltage V, , V
, can be changed from (1/2) E standard to O standard. If the magnitude of the external magnetic field H is known in advance and only its direction is to be detected, the direction of the external magnetic field H can be found from the value of the output voltage Vl of the full bridge circuit and the sign of the output voltage V2 at that time. Can be done. Therefore, in the magnetic orientation detection device according to the present invention, the detection element portion can be formed in the same manufacturing process as an IC, so a highly accurate device can be sufficiently miniaturized, and an oscillation circuit is not required in the drive control circuit portion. It is inexpensive because it does not require Furthermore, in FIG. 1 showing the configuration of the above-described embodiment, instead of attaching the permanent magnet 12 under the insulating substrate 1, CoPt or the like is sputtered and deposited on another insulating substrate to form a film. Then, the film is etched to form a permanent magnet as a bias magnet. An insulating film is deposited and etched on the permanent magnet, and an insulating substrate 1 is formed.
form an insulating section in place of the Below, in the same way as above,
A sensor section of a magnetic orientation detecting device can be formed on the insulating section. The magnetic orientation detecting device having such a configuration has the same functions and effects as those of the above-described embodiment, and since it is not necessary to attach a permanent magnet, it can be made even more compact and highly accurate. Further, by using a semiconductor substrate as the other insulating substrate, it is also possible to form the signal processing circuit as an integrated IC. Effects of the Invention The present invention is formed by connecting in series a fixed resistance element made of a resistive thin film and a magnetoresistive element made of a thin wire-like ferromagnetic film on an insulating substrate. A first half-bridge circuit and a second half-bridge circuit arranged such that the directions are orthogonal to each other, and the longitudinal direction of the magnetoresistive element of the first half-bridge circuit and the longitudinal direction of the magnetoresistive element of the second half-bridge circuit. Approximately 45 mm each in the longitudinal direction
The sensor section includes a permanent magnet arranged so that a predetermined bias magnetic field is applied in the direction of I.
Since it is formed in the same manner as the manufacturing process of C, there is no need for assembly and it can be miniaturized with high precision. Furthermore, since a half-bridge circuit is used, an oscillation circuit is not required, resulting in low cost.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the configuration of a sensor section of a magnetic direction detecting device according to a specific embodiment of the present invention and the direction of an external magnetic field. Figure 2 shows the first half-bridge circuit 2 in Figure 1.
1 is a circuit diagram showing 1. FIG. 3 is an explanatory diagram showing two output signals from the sensor section of the device according to the embodiment. FIG. 4 is an explanatory diagram showing a change in internal resistance when a magnetic field is applied to a magnetoresistive element as viewed from a ferromagnetic thin film. Insulating substrate 2, 7 8 Fixed resistance element Second output terminal First half-pre-second half-preferential magnetic resistance element 6 First output terminal 12 Permanent magnet edge circuit Edge circuit

Claims (1)

[Scope of Claims] A first half-bridge circuit formed by connecting in series a fixed resistance element made of a resistive thin film and a magnetoresistive element made of a thin wire-shaped ferromagnetic thin film on an insulating substrate; A fixed resistance element made of a resistor thin film and a magnetoresistive element made of a fine wire-shaped ferromagnetic thin film whose longitudinal direction is perpendicular to the longitudinal direction of the magnetoresistive element of the first half-bridge circuit are connected in series on an insulating substrate. a second half-bridge circuit formed by being connected to the first half-bridge circuit; 1. A magnetic orientation detection device comprising: a permanent magnet arranged so that a predetermined bias magnetic field is applied in the degree direction.