JPH11329185A - Magnetic sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic sensor having a small gap between a detecting surface of a magnetic resistance element and a non-magnetic protective case. SOLUTION: A magnetic resistance element 12 is horizontally mounted on a circuit board 14, by electrically connecting terminal electrodes 17a, 17b directly to a circuit pattern 19 of the circuit board 14 by means of soldering or a conductive adhesive. On the other hand, a lead terminal 21 is fixed to the circuit board 14 by inserting it in an installation hole 14a provided on the circuit board 14, and electrically connecting a head part of the lead wire 21 directly to the circuit pattern 19 by means of soldering or the conductive adhesive. A magnet 13 is mounted by means of the adhesive on the surface opposite to the mounting surface of the magnetic resistance element 12 on the circuit board 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic sensor, for example, detecting characters, symbols, patterns, and the like printed with magnetic ink, detecting the rotational speed of a motor by counting the teeth of a magnetic gear, Alternatively, the present invention relates to a magnetic sensor used when measuring a rotation angle of a magnetic rotating body.

[0002]

2. Description of the Related Art An example of a conventional magnetic sensor of this type is shown in FIG.
It is shown in FIG. The magnetic sensor 1 includes a magnetoresistive element 2, a circuit board 3 on which the magnetoresistive element 2 is mounted, a magnet 4 for applying a bias magnetic field to the magnetoresistive element 2, a holder 5 for holding the magnet 4, and a non-magnetic protective case 6. It consists of.
The magnetoresistive element 2 is provided with a magnetoresistive pattern on its upper surface 2a (hereinafter referred to as a sensing surface 2a). The magnetoresistive element 2 is arranged on a circuit board 3, and a magnetoresistive pattern provided on a detection surface 2a is electrically connected to a lead terminal 8 via a wire 7 (or a lead frame).
The circuit board 3 is fixed on one magnetic pole of the magnet 4.
Further, the magnet 4 has a holder 5 made of an insulating resin material.
Is fitted in the concave portion 5a formed in the recess. This magnet 4
Apply a predetermined magnetic bias to the magnetoresistive element 2. The magnetoresistive element 2 and the magnet 4 are housed in a non-magnetic protective case 6 together with the holder 5.

[0003]

The conventional magnetic sensor 1 uses the wire 7 or the like for electrical connection between the magnetoresistive element 2 and the lead terminal 8. It had to be routed over the detection surface 2a.
For this reason, the gap dimension D between the detection surface 2a and the non-magnetic protection case 6 increases by the height of the wire 7, the magnetic sensitivity of the magnetoresistive element 2 decreases, and the output of the magnetic sensor 1 decreases. There was a problem.

An object of the present invention is to provide a magnetic sensor having a small gap dimension between a detection surface of a magnetoresistive element and a nonmagnetic protective case.

[0005]

In order to achieve the above object, a magnetic sensor according to the present invention comprises: (a) a magnetoresistive element having a terminal electrode provided on a surface thereof; A magnet for applying a bias magnetic field, (c) a support member provided with a conductor pattern on the surface thereof for mounting the magnetoresistive element, and (d) a non-conductive member for housing the magnetoresistive element, the magnet and the support member. With a magnetic protective case,
(E) The terminal electrode of the magnetoresistive element is directly connected to the conductor pattern of the support member.

According to the above configuration, since the terminal electrodes of the magnetoresistive element are directly connected to the conductor patterns of the support member, it is necessary to use a wire, a lead frame or the like for electrical connection between the magnetoresistive element and the support member. Therefore, the gap dimension between the detection surface of the magnetoresistive element and the non-magnetic protective case is reduced.

Further, by providing a gap between the sensing surface of the magnetoresistive element and the non-magnetic protective case, even if the detected object collides with the non-magnetic protective case, the mechanical shock at this time is not affected by the magnetic shock. Therefore, no piezoelectric noise is generated in the magnetoresistive element.

Further, the magnetic sensor according to the present invention is characterized in that the support member is provided with one of a concave portion for a magnetoresistive element and a hole for a magnetoresistive element. The magnetoresistive element is
Since the positioning is performed by being inserted into the recess for the magnetoresistive element or the hole of the magnetoresistive element, the positional accuracy of the magnetoresistive element is improved, and the output characteristics of the magnetic sensor are further stabilized. In addition, by adopting a structure in which the magnet is held by the support member or the holder, the fixing of the magnet is ensured, and the positioning of the magnet when assembling the magnet to the non-magnetic protective case is facilitated.

Furthermore, by mounting a resistance element and a transistor in addition to the magnetoresistive element on the support member, the mounting density of the support member is increased. Here, by mounting these transistors and resistance elements on the surface opposite to the surface on which the magnetoresistance element is mounted, the mounting density of the support member can be further increased.

Further, the magnetic sensor according to the present invention further includes a shaft rotatably mounted on the non-magnetic protective case, wherein the tip of the shaft is opposed to a magnetoresistive element, and the tip of the shaft is connected to the tip of the shaft. The magnet is disposed at the tip of the shaft so that the magnet is positioned between the detection surface of the magnetoresistive element, and the magnet is disposed on the shaft according to the rotation angle of a rotating body fixed to the shaft. The magnets are rotated to change respective resistance values of a pair of magnetoresistive patterns provided on the detection surface of the magnetoresistive element.

According to the above configuration, since the magnet does not face the magnetoresistive element with the support member interposed therebetween, the gap size between the sensing surface of the magnetoresistive element and the magnet can be reduced, and excellent output characteristics can be obtained. Can be

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the magnetic sensor according to the present invention will be described below with reference to the accompanying drawings. In each embodiment, the same components and the same portions are denoted by the same reference numerals.

[First Embodiment, FIGS. 1 and 2] As shown in FIG. 1, a magnetic sensor 11 includes a magnetoresistive element 12, a magnet 13 for applying a bias magnetic field to the magnetoresistive element 12, and components 12, 13. Circuit board 1 which is a support member for mounting
4 and a non-magnetic protective case 16.

As shown in FIG. 2, the magnetoresistive element 12
A substrate 15, a magnetoresistive pattern 16 provided on an upper surface 15a of the substrate 15 (hereinafter, referred to as a detection surface 15a),
Terminal electrodes 17a and 17b provided at both ends of substrate 15
Consists of The substrate 15 is made of InS by vapor deposition on an insulator substrate.
A substrate formed with a b film or the like, a single crystal semiconductor substrate such as InSb, or a composite substrate in which a separately formed semiconductor thin film or single crystal substrate is attached to an insulating substrate with an adhesive, or the like is used. The lower surface 15b facing the detection surface 15a is a mounting surface for the magnetoresistive element 12. Magnetic resistance element 12
The resistance value increases as the magnetic field increases. The magnetoresistive pattern 16 has a meandering shape to obtain a predetermined magnetoresistive value, and has a high sensitivity by increasing the ratio W / L of the width W to the length L of the segment of the magnetoresistive pattern 16.

The magnetoresistive element 12 has terminal electrodes 17a, 1
7b is mounted horizontally on the circuit board 14 by electrically connecting the circuit pattern 7b and the circuit pattern 19 of the circuit board 14 electrically by a method such as soldering or a conductive adhesive. Further, an insulating tape 2 is provided on the detection surface 15a of the magnetoresistive element 12 to prevent a short circuit with the non-magnetic protective case 16.
0 is pasted. The thickness of the insulating tape 20 is
For example, it is about 20 μm. As the circuit board 14,
An epoxy or polyimide resin substrate containing glass fiber, a paper epoxy substrate, an alumina substrate, or the like is used. On the other hand, the lead terminal 21 is inserted into the through hole 14a provided in the circuit board 14, and the head of the lead terminal 21 and the circuit pattern 19 are electrically connected directly to the circuit board 14 by a method such as soldering. Fixed.

A magnet 13 is mounted on the surface of the circuit board 14 opposite to the surface on which the magnetoresistive element 12 is mounted, using an adhesive. This magnet 13 may be a permanent magnet or an electromagnet. The magnet 13 faces the magnetoresistive element 12 with the circuit board 14 interposed therebetween. Parts 12, 13, 21
Is mounted together with the filler 24 in the non-magnetic protective case 16. For the filler 24, an epoxy resin or the like having excellent moisture resistance and relatively high mechanical strength is used. The non-magnetic protective case 16 is made of beryllium copper, phosphor bronze, brass, nickel silver, non-magnetic stainless steel, aluminum,
It is made of a non-magnetic material such as ceramic and resin.

As shown in FIG. 1, the magnetic sensor 11 having the above-described configuration is configured such that, for example, a detection object made of a magnetic material is indicated by an arrow A.
Move in the direction shown by the arrow, and the detection surface 15
When passing over a, the bias magnetic field of the magnet 13 concentrates on the magnetoresistive pattern 16, so that the resistance value of the magnetoresistive pattern 16 increases. As a result, the output voltage of the magnetic sensor 11 changes, and the passage of the detected object is detected. And since the magnetoresistive element 12 was surface-mounted on the circuit board 14,
As compared with the conventional mounting structure using wires and lead frames, the mounting operation can be made extremely easy, and the manufacturing cost can be reduced. Further, since it is not necessary to route a wire or a lead frame on the detection surface 15a of the magnetoresistive element 12, the gap dimension D between the detection surface 15a and the non-magnetic protective case 16 can be reduced. An excellent magnetic sensor 11 can be obtained.

[Second Embodiment, FIG. 3] As shown in FIG. 3, the magnetic sensor 31 of the second embodiment is the same as the magnetic sensor 11 of the first embodiment, except that
This is the same as the one provided with the recess 32 for the magnetoresistive element. After the magnetoresistive element 12 is inserted into the recess 32, the terminal patterns 17a and 17b and the circuit pattern 1 on the circuit board 14 are removed.
9 are electrically connected directly by a method such as soldering. In the magnetic sensor 31 having the above configuration, since the magnetoresistive element 12 is positioned by the concave portion 32, the positional accuracy of the magnetoresistive element 12 can be improved, and the output characteristics of the magnetic sensor 31 can be further stabilized. .

[Third Embodiment, FIG. 4] As shown in FIG. 4, the magnetic sensor 41 of the third embodiment differs from the magnetic sensor 11 of the first embodiment in that a hole 42 for a magnetoresistive element is formed in the circuit board 14. It is the same as the one provided. After the magnetoresistive element 12 is inserted into the hole 42, the terminal electrodes 17a, 17
b and the circuit pattern 19 of the circuit board 14 are electrically connected directly by a method such as soldering. In the magnetic sensor 41 having the above configuration, since the magnetoresistive element 12 is positioned by the hole 42, the positional accuracy of the magnetoresistive element 12 can be improved, and the output characteristics of the magnetic sensor 41 can be further stabilized. .

[Fourth Embodiment, FIG. 5] As shown in FIG. 5, the magnetic sensor 51 of the fourth embodiment has a magnetoresistive element 1
2 and the resistance element 52 and an amplifying transistor (not shown) are mounted on one surface of the circuit board 14 and the magnet 1
The circuit board 14 is joined to a holder 53 that holds the circuit board 3. The amplifying transistor amplifies a voltage change amount corresponding to a magnetic resistance change amount extracted from an output terminal of the magnetoresistive element. The resistance element 52 is for adjusting the operating point of the amplification transistor. It is preferable that the mounting height of the resistance element 52 and the amplification transistor be equal to or smaller than the mounting height of the magnetoresistive element 12. The mounting height of the resistance element 52 and the like is
If the height is higher, the gap dimension D between the detection surface 15a of the magnetoresistive element 12 and the non-magnetic protective case 16 is increased by the resistance element 52 and the like. Thus, the circuit board 1
The mounting density of the circuit board 14 can be increased by mounting a resistance element 52 and an amplifying transistor in addition to the magnetoresistive element 12 on the circuit board 4.

The magnet 13 is fitted in a concave portion 53a formed in a holder 53 made of an insulating resin material.
Is held. Thereby, fixing of the magnet 13 is ensured, and positioning of the magnet 13 when assembling the magnet 13 to the non-magnetic protective case 16 is facilitated. The holder 53 to which the circuit board 14 is bonded is housed in the non-magnetic protective case 16. A gap 55 is provided between the detection surface 15 a of the magnetoresistive element 12 and the upper inner wall surface of the non-magnetic protective case 16. If the detection surface 15a is in contact with the non-magnetic protective case 16, when the detected object collides with the non-magnetic protective case 16, the mechanical shock at this time is transmitted to the magneto-resistive element 12, and This is because a piezo signal is output and becomes noise.

[Fifth Embodiment, FIG. 6] As shown in FIG. 6, the magnetic sensor 61 of the fifth embodiment is different from the magnetic sensor 51 of the fourth embodiment in that a resistance element 52 and an amplifying transistor are replaced by a circuit board. 14 is the same as that mounted on the surface opposite to the surface on which the magnetoresistive element 12 is mounted. The circuit board 14 is provided with through holes 62, and electrically connects the circuit patterns 19 provided on the front and back surfaces. Magnet 13
Is formed in the holder 53 for holding the resistance element 52 and the amplifying transistor. The magnetic sensor 61 having the above-described configuration includes the resistance element 5
2 and the mounting height of the amplifying transistor is higher than that of the magnetoresistive element 12, the gap dimension D between the detection surface 15a of the magnetoresistive element 12 and the non-magnetic protective case 16 is increased by the resistance element 52 and the like. Don't worry. Also,
By mounting the components 12 and 52 on both sides of the circuit board 14, the mounting density of the circuit board 14 can be further increased.

[Sixth Embodiment, FIG. 7] As shown in FIG. 7, a magnetic sensor 71 of a sixth embodiment has a magnetoresistive element 12 mounted in a concave portion 72a provided above a support member 72, The magnet 13 is fitted into a concave portion 72b provided at a lower portion of the support member 72. The support member 72 is made of an insulating resin material, and a circuit pattern 73 is formed on an upper surface thereof by a method such as electroless plating. The magnetoresistive element 12 is horizontally mounted on the support member 72 by electrically connecting the terminal electrodes 17a and 17b and the circuit pattern 73 of the support member 72 directly by a method such as soldering. On the other hand, the lead terminal 21 is inserted into a through hole 72c provided in the support member 72, and the head of the lead terminal 21 and the circuit pattern 73 are electrically connected directly by a method such as soldering, whereby the support member 72 is electrically connected. It is fixed to.
In the magnetic sensor 71 having the above configuration, since the magnetoresistive element 12 and the magnet 13 are mounted on the support member 72, the accuracy of the relative positional relationship between the magnetoresistive element 12 and the magnet 13 is improved, and the sensitivity characteristic is improved. Magnetic sensor 71 can be obtained.

[Seventh Embodiment, FIGS. 8 to 13] As shown in FIG. 8, an angle sensor 81 is roughly composed of a shaft 82, a magnet 86, a magnetoresistive element 87, bearings 88 and 89, and a nonmagnetic protective case 100. It consists of. Shaft 82
Has a magnet 86 at its tip. The rectangular magnet 86 is disposed so as to include the axial center line L of the shaft 82 on one surface thereof in order to improve the linearity of the output voltage of the magnetoresistive element 87 with respect to the rotation angle of the shaft 82. . The other end of the shaft 82 is fixed to a rotating body (not shown) such as a motor. Non-magnetic protective case 10
Numeral 0 denotes a cylindrical shape, in which bearings 88 and 89, a part of a shaft 82, a magnet 86 and a magnetoresistive element 87 are accommodated. As the bearings 88 and 89, ball bearings are used, contact the outer peripheral surface of the shaft 82, and support the shaft 82 in a rotatable state.

The detection surface 87a of the magnetoresistive element 87 is shown in FIG.
As shown in FIG. 5, a pair of semicircular magneto-resistors MR1, M
R2 is arranged at a predetermined interval. This magnetoresistive element 87 is provided so as to face the magnet 86. As shown in FIG. 10, the magnetic resistors MR1 and MR2 are connected in series, a power terminal 91 and a ground terminal 93 are connected to one end of each of the magnetic resistors MR1 and MR2, and a relay between the magnetic resistors MR1 and MR2. Output terminal 9 on wire
2 are connected. A terminal electrode 111 is provided at an end of the magnetoresistive element 87.

The magnetoresistive element 87 is mounted on the circuit board 114 by soldering the terminal electrode 111 and the circuit pattern 119 of the circuit board 114. further,
The circuit board 114 is joined to the upper surface of the holder 120 holding the magnetic yoke 121. On the other hand, the lead terminal 91 penetrates the circuit board 114 and the holder 120 and the lead terminal 9
The head 1 and the circuit pattern 119 are electrically connected directly by a method such as soldering.

Next, the angle sensor 81 having the above configuration will be described.
The operation and effect of will be described. Magnetic resistors MR1 and M
Assuming that the resistance value of R2 is R ₁ and R ₂ and the power supply voltage input to the power supply terminal 91 is Vi, the output voltage Vo of the output terminal 92 is expressed by the following equation (1). Vo = {R ₂ / (R ₁ + R ₂ )} × Vi (1)

In the seventh embodiment, as shown in FIG. 9, when the magnetoresistive elements MR1 and MR2 face the magnet 86 with the same facing area, the rotation angle of the shaft 82 is set to 0 degree. ing. Therefore, the shaft 82
MR1 and MR when the rotation angle of
2 of the resistance value R ₁ = R ₂ = R _0, and the more the (1) formula, the output voltage Vo ₁ of the magnetoresistive element 87 becomes the following equation (2). Vo ₁ = Vi / 2 (2)

Next, as shown in FIG. 11, when the detected object rotates forward and the shaft 82 rotates clockwise, the magnet 86 rotates with the rotation of the shaft 82, and the magnetoresistive element M
The facing area between R2 and the magnet 86 decreases, and the facing area between the magnetoresistive element MR1 and the magnet 86 increases by the decrease in the facing area. Therefore, the magnetic flux density from the magnet 86 to the magnetoresistive element MR2 decreases, and the magnetic flux density to the magnetoresistive element MR1 increases. That is, the resistance R ₁ of the magnetic body MR1 is R ₀ +
ΔR, and the resistance value R ₂ of the magnetic resistor MR2 is R ₀ −ΔR
Becomes As a result, according to the above equation (1), the magnetoresistive element 8
Output voltage Vo ₂ of 7, and becomes the following equation (3) (FIG. 13
Point B). Vo ₂ = (Vi / 2) − (Vi · △ R / 2R ₀ ) (3)

Next, as shown in FIG. 12, when the detection object rotates in the reverse direction and the shaft 82 rotates counterclockwise, the facing area between the magnetoresistive element MR1 and the magnet 86 decreases, and the magnetoresistive element MR2 and the magnet 86 The facing area of 86 increases. Magnetic resistor M
Resistance R ₁ of R1 is R ₀ - △ R, and the magnetic resistor MR2
Resistance value R ₂ of the R ₀ + △ R. As a result, the above (1)
From the equation, the output voltage Vo ₃ of the magnetoresistive element 87 is represented by the following equation (4) (see point C in FIG. 13). Vo ₃ = (Vi / 2) + (Vi △ R / 2R ₀ ) (4)

FIG. 13 is a graph showing the relationship between the rotation angle of the shaft 82 and the output voltage of the magnetoresistive element 87. Thus, the angle sensor 81 can measure the rotation angle of the detected object as a change in the output voltage of the magnetoresistive element 87. Since the angle sensor 81 does not need to route a wire or a lead frame on the detection surface 87a of the magnetoresistive element 87, the gap dimension between the detection surface 87a and the magnet 86 can be reduced, and the angle can be reduced. Sensor 8
1 can be increased.

[Other Embodiments] The magnetic sensor according to the present invention is not limited to the above embodiment, but can be variously modified within the scope of the gist. For example, it goes without saying that the magnetoresistive element may be configured using a semiconductor magnetoresistive element or a ferromagnetic thin film.

[0033]

As is apparent from the above description, according to the present invention, since the terminal electrodes of the magnetoresistive element are directly connected to the conductor patterns of the support member, it is necessary to use wires and lead frames. And the gap between the sensing surface of the magnetoresistive element and the non-magnetic protective case or the gap between the sensing surface of the magnetoresistive element and the magnet can be reduced, and the magnetic field having excellent sensitivity can be obtained. A sensor can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first embodiment of a magnetic sensor according to the present invention.

FIG. 2 is a perspective view of the magnetoresistive element shown in FIG.

FIG. 3 is a sectional view showing a second embodiment of the magnetic sensor according to the present invention.

FIG. 4 is a sectional view showing a third embodiment of the magnetic sensor according to the present invention.

FIG. 5 is a sectional view showing a fourth embodiment of the magnetic sensor according to the present invention.

FIG. 6 is a sectional view showing a fifth embodiment of the magnetic sensor according to the present invention.

FIG. 7 is a sectional view showing a sixth embodiment of the magnetic sensor according to the present invention.

FIG. 8 is a sectional view showing a seventh embodiment of the magnetic sensor according to the present invention.

FIG. 9 is an explanatory diagram showing a positional relationship between a magnetoresistive element and a magnet.

FIG. 10 is an electric circuit diagram of a magnetoresistive element.

FIG. 11 is an explanatory diagram showing a positional relationship between a magnetoresistive element and a magnet when a shaft rotates clockwise.

FIG. 12 is an explanatory diagram showing a positional relationship between a magnetoresistive element and a magnet when a shaft rotates in a counterclockwise direction.

FIG. 13 is a graph showing a rotation angle of a shaft and an output voltage characteristic of a magnetoresistive element.

FIG. 14 is a sectional view showing a conventional magnetic sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Magnetic sensor 12 ... Magnetic resistance element 13 ... Magnet 14 ... Circuit board 15a ... Detection surface 16 ... Non-magnetic protective case 17a, 17b ... Terminal electrode 19 ... Conductor pattern 31, 41, 51, 61, 71 ... Magnetic sensor 32 ... Recess for magneto-resistive element 42 ... Hole for magneto-resistive element 52 ... Resistant element 53 ... Holder 55 ... Void 72 ... Support member 73 ... Conductor pattern 81 ... Angle sensor 82 ... Shaft 86 ... Magnet 87 ... Magnetic resistive element 87a ... Detection surface MR1 , MR2 ... Magnetic resistor

Claims (7)

[Claims] 1. A magnetoresistive element having a terminal electrode provided on a surface thereof, a magnet for applying a bias magnetic field to the magnetoresistive element, and a support member having a conductor pattern provided on a surface thereof for mounting the magnetoresistive element. A non-magnetic protective case that houses the magnetoresistive element, the magnet and the support member, wherein a terminal electrode of the magnetoresistive element and a conductor pattern of the support member are directly connected. Magnetic sensor. 2. The magnetic sensor according to claim 1, wherein a gap is provided between the detection surface of the magnetoresistive element and the non-magnetic protective case. 3. The magnetic sensor according to claim 1, wherein the support member has one of a concave portion for a magnetoresistive element and a hole for a magnetoresistive element. 4. The magnetic sensor according to claim 1, further comprising a holder for holding the magnet. 5. The magnetic sensor according to claim 1, wherein at least one of a transistor and a resistance element is mounted on the support member. 6. The magnetic sensor according to claim 1, wherein the magnet is held by the support member. 7. A shaft rotatably attached to the non-magnetic protective case, wherein a tip of the shaft faces the magnetoresistive element, and a tip of the shaft and a sensing surface of the magnetoresistive element. The magnet is arranged at the tip of the shaft so that the magnet is located between the shaft and the magnet arranged on the shaft is rotated according to the rotation angle of the rotating body fixed to the shaft. 2. The magnetic sensor according to claim 1, wherein each of the pair of magnetoresistive patterns provided on the detection surface of the magnetoresistive element changes a resistance value.