JPH05126512A - Angle detector - Google Patents

Abstract

PURPOSE:To achieve miniaturization and low cost by forming a conductor pattern on a surface inside a housing enclosing a rotary body and then mounting a magnetic detection part and other electronic parts for achieving a function of printed-circuit board. CONSTITUTION:A conductor pattern 21 of a specified circuit is formed by copper-plating a bottom surface inside a housing and then a magnetic resistance element 13 which is a magnetic detection part is mounted on it. In a rotary body 16, permanent magnets l7a and 17b are mounted to the tip opposingly in different poles, they are interlocked to an object to be measured for rotation by a rotary shaft 18 through the housing 12, and then a measurement magnetic field ranges is + or -90 degrees by a stopper 24 inside the housing 12. Then, when the magnets 17a and 17b of the rotary body 16 are rotated according to rotation of the object to be measured, a magnetic field according to the rotary angle is applied to the element 13, thus achieving miniaturization and low cost of a device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an angle detector for detecting a rotation angle of an object to be measured.

In recent years, a magnetoresistive (MR) element has been mainly used as a detection element when detecting the rotation angle of an object to be measured. An angle detector using this MR element is desired to be small and inexpensive.

[0003]

2. Description of the Related Art FIG. 4 is a block diagram of a conventional angle detector. FIG. 4A is a side sectional view, and FIG. 4B is a partial perspective view of the detection portion.

In the angle detector 11 _A shown in FIGS. 4A and 4B, a printed circuit board 1 in which a barber pole type MR element 13 and other electronic parts are mounted in a housing 12
4 is arranged, and the output connector 15 extending to the outside of the housing 12 is connected to the printed circuit board 14.

On the other hand, permanent magnets 17a and 17b are attached to the tip of the substantially U-shaped rotating body 16 and face each other. M between the opposing permanent magnets 17a and 17b
The rotating body 16 is arranged so that the R element 13 is located.
In this case, the permanent magnets 17a and 17b facing each other are positioned with different polarities on the MR element 13 side. Rotating body 16
Is rotated by the rotating shaft 18 attached to the center,
The rotating shaft 18 is connected to an object to be measured (not shown).

In such an angle detector 1 _A , when the rotating body is rotated by the rotating shaft 18 connected to the object to be measured, the magnetic field across the MR element 13 by the permanent magnets 17a and 17b is changed. The MR element 13 outputs a different voltage according to the change in the magnetic field direction, thereby recognizing the rotational position of the rotating body 16.

[0007]

However, as described above, the printed circuit board 14 for mounting the MR element 13 and connecting the output connector 15 is provided in the housing 12. The printed circuit board 14 has a thickness of 1.6 m, for example.
About 1 m, and housing 1 to ensure safety
It is separated from the inner bottom surface of 2 by about 3 mm. Therefore,
The inside of the housing 12 requires a space for the printed circuit board 14, and there is a problem that the size cannot be reduced and the cost cannot be reduced.

Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide an angle detector which is downsized and reduced in cost.

[0009]

SUMMARY OF THE INVENTION The above-mentioned problems are solved by rotating opposing permanent magnets fixed to a rotating body contained in a housing around a magnetic detecting portion, and by changing the magnetic field direction from the permanent magnet. In the angle detector that detects the rotation angle of the rotating body by the change in the output of the electronic component, a predetermined conductor pattern is formed on the inner bottom surface of the housing, and an electronic component that forms the magnetic detection unit and the predetermined circuit is mounted. Will be solved by.

[0010]

As described above, the magnetic detector and other electronic components are surface-mounted on the conductor pattern formed on the inner bottom surface of the housing. That is, the inner bottom surface of the housing plays a role similar to that of the printed circuit board.

As a result, a printed circuit board is not required, so that the cost can be reduced, and it is not necessary to secure a space for the cost, and the size can be reduced.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a block diagram of an embodiment of the present invention.
1A is a vertical sectional view, FIG. 1B is an upper sectional view, and FIG. 1C is a sectional view of chip mounting. The same components as those in FIG. 4 are designated by the same reference numerals.

In the angle detector 11 _B shown in FIGS. 1A and 1B, an MR element (which may be a Hall element) 13 as a magnetic detector is arranged in a housing 12.

The housing 12 is formed of an injection molding material such as PBT (polybutylene terephthalate), and a copper film is plated on the inner bottom surface to form a conductor pattern 21 of a predetermined circuit. The MR element 13 is mounted on the conductor pattern 21 by soldering, and the output connector 15 arranged outside is connected.

Further, on the conductor pattern 21 is shown in FIG.
As shown in (C), for example, an electronic component (chip) 22 that constitutes an amplifier, a constant current circuit, a temperature compensation circuit, etc. is mounted by solder 23.

The MR element 13 is a so-called barber pole type, and an insulating layer such as SiO ₂ (silicon oxide film) is formed on a substrate made of silicon or the like, and a zigzag-shaped magnetic pattern is formed on the insulating layer. Then, uniaxial magnetic anisotropy (internal magnetization) Mi is applied in the longitudinal direction of the magnetic pattern, and thereafter, a conductive film such as Au is obliquely formed at regular intervals.

In such an MR element 13, the angle θ formed by the direction of the internal magnetization Mi of the magnetic material pattern and the current I flowing through the conductive film is π / 4 + nπ (or 7 / 4π-nπ) (n
= 0.1 ...), the output can be increased.

In order to compensate the temperature characteristics of permanent magnets 17a and 17b, which will be described later, an auxiliary magnet may be attached on the back surface of the MR element 13 with a polarity perpendicular to the detection direction. This auxiliary magnet tries to absorb the change in the resistance value of the MR element 13 due to the temperature by the change in the magnetic field detection sensitivity, and is in the easy axis of magnetization of the MR element 13 (the angle of the rotating body is 0 °). It will be compensated in.

On the other hand, the rotating body 16 is made of, for example, electromagnetic soft iron (J
IS C 2504), and in particular, it is formed of a magnetic metal of a soft magnetic material such as electromagnetic steel, silicon mesh, etc. in a substantially U-shape. Permanent magnets 17a, 17b are provided at the tip of the rotating body 16.
However, they are fixed with different poles facing each other. Permanent magnet 17
a and 17b are, for example, rare magnets (samarium-cobalt, neodymium) or plastic rare-magnets suitable for extrusion (samarium-cobalt, neodymium).
Is formed by.

In this case, the rotating body 16 stabilizes the magnetic characteristics of the opposing magnetic surfaces of the opposing permanent magnets 17a and 17b by the shunt effect (uniformization by reducing the generated magnetic field).

The rotating body 16 is rotated by a rotating shaft 18 attached to the center thereof, and the rotating shaft 18 is connected to an object to be measured (not shown). The rotary shaft 18 penetrates the housing 12 with a bearing 18a interposed. The bearing is made of, for example, a ceramic or non-magnetic stainless ball bearing or a non-magnetic material having a copper-based sintered structure.

Inside the housing 12, the rotating body 1
In order to rotate 6 within the range of ± 90 °, the stopper 22
Is formed. That is, the magnetic field direction of the MR element 13 is 1
Since the hysteresis occurs when the angle exceeds 80 °, the measurement magnetic field range is set to ± 90 ° by the stopper 24.

Although not shown, the outer periphery of the housing 12 is magnetically shielded with, for example, PC permalloy, PB permalloy, silicon copper or the like. This is because the MR element 13 also detects a weak magnetic field, so that the influence of the external magnetic field is avoided.

Such an angle detector 11 _B has the permanent magnets 17 a, 1 a of the rotating body 16 when the object to be measured rotates.
When 7b rotates, a magnetic field corresponding to the rotation angle between the permanent magnets 17a and 17b is applied to the MR element 13.

Here, FIG. 2 shows a graph of output characteristics of the MR element of FIG. The MR element 13 changes its resistance value depending on the strength of the magnetic field to be detected, so that the output voltage changes. That is, as shown in the graph of FIG. 2, the relationship between the output voltage and the rotation angle of the rotating body 16 can be obtained.

As described above, the angle detector 11 _B includes the MR element 13 in the housing 12 itself without providing a printed circuit board.
By mounting the chip 22 and the like, the cost can be reduced and the size can be reduced without the need to secure the thickness and the arrangement gap of the printed circuit board itself.

Next, FIG. 3 shows a block diagram of another embodiment of the present invention. In the description of FIG. 1, although the case where a magnetic shield on the outer circumference of the housing 12 in the angle detector 11 _B, the angle detector 11 _B of FIG. 3 Housing 1
2 is internally provided with a shield member 25 for magnetically shielding. The shield member 25 is formed of a magnetic metal such as PC permalloy, PB permalloy, and silicon copper, which are similar to those described above.

In this case, the shield member 25 is completely covered with the injection molding material for the insulating housing 12, and is insulated from the conductor pattern 21 formed on the inner bottom surface.

As a result, the magnetic shield is not provided on the outer circumference, so that the size is reduced as a whole.

[0030]

As described above, according to the present invention, the conductor pattern is formed on the inner bottom surface of the housing, the electronic parts forming the magnetic detection portion and the predetermined circuit are mounted, and the shield member is provided inside the housing. As a result, it is possible to reduce the size of the entire device and reduce the cost.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is a graph of output characteristics of the MR element of FIG.

FIG. 3 is a configuration diagram of another embodiment of the present invention.

FIG. 4 is a configuration diagram of a conventional angle detector.

[Explanation of symbols]

11 _A , 11 _B Angle detector 12 Housing 13 MR element 16 Rotating body 15 Rotating body 17a, 17b Permanent magnet 18 Rotating shaft 21 Conductor pattern 22 Chip 24 Stopper 25 Shield member

Claims (2)

[Claims] 1. An opposing permanent magnet (17a, 17) fixed to a rotating body (16) contained in a housing (12).
b) is rotated around the magnetic detection part (13), and the rotation angle of the rotating body (16) is changed by the output change of the magnetic detection part (13) depending on the magnetic field direction from the permanent magnets (17a, 17b). In the angle detector for detecting, a predetermined conductor pattern (21) is formed on the inner bottom surface of the housing (12), and the magnetic detector (13) and an electronic component (22) forming a predetermined circuit are mounted. An angle detector characterized in that 2. The angle detector according to claim 1, wherein a shield member (25) for magnetically shielding is provided inside the housing (12).