JPS60155917A - Detection apparatus - Google Patents

Abstract

PURPOSE:To make it possible to improve the strain of an output wave form by utilizing a magnetic field formed by a permanent magnet, by arranging an MR element in the magnetic field between the permanent magnet and magnetic pole teeth and inclining the surfaces of usually parallel magnetic pole teeth and the magnetism-sensitive direction of the MR element by an angle alpha deg.. CONSTITUTION:This detection apparatus detects the relative position of a movable part 21 and a fixed part 20 when said movable part 21 linearly moves along the fixed part 20. The movable part 21 is constituted of a substrate 12 having a magnetism-sensitive part 13 comprising an MR element and terminal parts 14, 15 formed to the surface thereof and a permanent magnet 16 for supplying a bias magnetic field while the fixed part 21 has magnetic pole teeth with definite scored cycles formed to the surface thereof opposed to the movable part 20. When the movable part 21 moves to + or -X'-directions along the fixed part 20, line of magnetic force directed to a stator 20 from the permanent magnet 16 changes in its direction corresponding to the uneven shape of the magnetic pole teeth. By this mechanism, the non-linear region of MR characteristics is avoided and a region relatively good in linearity can be used and, therefore, the strain of an output wave form is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is used to detect the distance traveled by a linearly moving object, the rotation angle of a rotary object, and the like.

The present invention relates to a detection device using a ferromagnetic i-thin film resistive element (hereinafter abbreviated as %MR element) having a magnetic anisotropy effect. , Configuration of Conventional Example and Its Problems FIG. 1 (M) and D) are a plan view and a front view showing an example of an MR element.

In FIG. 1, a magnetic sensing part 2 made of an MR element and external connection terminal parts 3 and 4 are formed on the surface of a substrate 1.
In Fig. 1, the magnetic sensing part 2 is a so-called magnetic sensor whose resistance value changes according to changes in magnetic field strength in the ±X direction, and whose resistance value hardly changes with respect to changes in magnetic field strength in other directions. It has an anisotropic effect.

FIG. 2 is a characteristic diagram of the MR element, showing changes in the resistance value of the magnetic sensing section 2 with respect to changes in magnetic field strength in the X direction. In the figure, a, C, el'l: Regions in which the change in resistance value with respect to magnetic field strength is non-linear;

d is a region with relatively good linearity.

A detection device using causticity of the MR element described in FIGS. 1 and 2 will be described below.

FIG. 3 shows an example of a conventional detection device using an MR element, and FIG. 3 (A) is a plan view of Fi, and (B) is a sectional view taken along the line A of FIG. In addition, in FIGS. 3(A) and 3(B), the same parts as in FIG. 1 are given the same reference numerals.

Now, this conventional detection device detects the relative positional relationship between the movable part 8 and the fixed part 9 when they move linearly. It is composed of a substrate 1 on which terminal portions 3 and 4 are formed, and a permanent magnet 7 that serves to supply a bias magnetic field. On the other hand, the fixed part 9 includes a large number of tooth-shaped irregularities (hereinafter referred to as magnetic pole teeth) made of a magnetic material on the surface facing the movable part 8. Further, although not shown, opposing surfaces of the movable part 8 and the fixed part 9 are held by a travel holding system such as a bearing so that they can move in parallel while maintaining a constant gap.

Now, as shown in FIG. 3(G), the magnetic sensing part 2 is connected to the external constant current source 10. Fixed resistor6.
Grounding 11. When the movable part 8 moves at a constant speed along the fixed part 9 while connected to the output terminal 6, a sine wave with a half period of the pitch period of the magnetic pole teeth of the fixed part 9 is output from the output terminal 6. It is generally known that similar outputs can be obtained. This is because the magnetic field generated by the permanent magnet 7 is influenced by the uneven shape of the magnetic pole teeth of the fixed part 9 and is periodically bent, and the magnetic field is bent periodically with respect to the magnetically sensitive part 2 of the movable part 8 (± X direction) component? This is because the resistance value of the magnetic sensing part 2 is.

As explained in FIG. 2, since it changes depending on the strength of the received magnetic field, a periodic sine wave-like output appears at the output terminal 6. This will be explained in more detail using Figure 4 of the Golden Brother.

However, the same parts as in FIG. 3 are given the same reference numerals, and redundant explanation will be omitted.

In Figure 4, 101 + 102+ 103+ 104+
1105 indicates typical lines of magnetic force generated by the permanent magnet 7. In FIG. 4, the magnetic sensing part 2 is at a position where the lines of magnetic force 103 pass.

Since the magnetic field lines 103 pass perpendicularly to the magnetic sensing part 2, ±
There is no component in the X direction, and the magnetic field is at a position of 0 as shown in the characteristic diagram of FIG. 2, and the resistance value of the magnetically sensitive portion 2 is at its maximum. Similarly, when the movable part 8 moves and the magnetically sensitive part 2 is positioned at the lines of magnetic force 101 and 105, the resistance value also reaches its maximum.

Next, considering the case where the movable part 8 moves and the magnetic sensing part 2 is located at the position of the magnetic field lines 102, the magnetic field lines 102 will pass diagonally through the magnetic sensing part 2. This line of magnetic force 102'i
When divided into orthogonal components, they can be separated into a component that passes perpendicularly through the magnetically sensitive part 2 and a component in the -X direction, and due to the magnetic field of the -X direction component, the resistance value of the magnetically sensitive part changes depending on the magnetic field strength. It changes accordingly. Similarly, for the magnetic field lines 104, +
A magnetic field with an x-direction component is generated. As shown in FIG. 2, the characteristics of the magnetically sensitive part 2 are symmetrical with respect to the magnetic field 0, so the movable part 8 moves at a constant speed, and the magnetically sensitive part 2 moves along the line of magnetic force 101. to position 105 (one cycle of magnetic pole teeth)
When moving, the resistance value change at that time is from 101 to 103
and 103 to 106 are symmetrical with respect to the position of the line of magnetic force 103. In other words, an output with a cycle that is half the pitch cycle of the magnetic pole teeth is obtained.

However, in the detection device configured as above,
Among the MR characteristics shown in Figure 2, plus the center of the magnetic field o'l,
Since it is used in both negative and negative directions, it has the disadvantage that the output signal is heavily distorted due to the influence of the nonlinear region C. In particular, if a high-precision, high-resolution detection device is required, it can be achieved to some extent by making the pitch period of the magnetic pole teeth of the fixed part 9 finer, but since signal detection becomes difficult, generally an electrical Interpolation methods are often used to increase the resolution of the signal.

In this case, from the standpoint of signal processing, it is desirable that the output waveform be close to a sine wave, but in conventional detection devices, linearity is poor due to the above-mentioned distortion, and it is difficult to achieve high resolution.

The drawbacks of the conventional method described above are due to the use of the nonlinear region C of the characteristics of the MR element shown in FIG. It is obvious that it is sufficient to use a region with good linearity (Li), but for this purpose, it is necessary to always use the magnetically sensitive part 2 in FIG.

It is necessary to apply a certain magnetic field in the +X or -X direction (the center of the area ``s'' or the center of the area d in Figure 2), and such a magnetic field (hereinafter referred to as an offset magnetic field) must be stabilized. It was difficult to supply the

OBJECTS OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks, and to make it possible to supply a stable offset magnetic field to an MR element with a simple configuration without increasing the number of parts.
It is an object of the present invention to provide a detection device that is highly precise and has a wide range of applications.

Configuration of the Invention The detection device of the present invention is configured to include first means and second means for performing relative movement while maintaining a constant gap,
The first means includes a ferromagnetic thin film resistance element having a magnetic anisotropy effect and a permanent magnet that applies a magnetic field thereto, and the second means includes a surface facing the first means, The ferromagnetic thin film resistance element includes a large number of tooth-shaped unevenness made of a magnetic material in the direction of relative movement thereof, and the ferromagnetic thin film resistance element is disposed in a magnetic field between the permanent magnet and the tooth-shaped unevenness. The magnetic field sensing direction of the resistance element is arranged to be in the relative motion direction, and the thin film surface of the first ferromagnetic thin film resistance element has a certain inclination with respect to the surface of the magnetic material on which the unevenness of the second means is formed. It is configured to be arranged at an angle, thereby realizing a highly precise detection device.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 5 shows a cross-sectional view of a main part of a detection device using an MR element according to an embodiment of the present invention, (A) is a plan view, and (A) is a (
It is a sectional view taken along the line B-B of A). .

This detection device detects the relative position of the movable part 21 and the fixed part 2o when they move linearly. Ah9
, a magnetic sensing part 13 consisting of a mouth element 1 is provided on the surface of the moving parts 2 and 41.
It is composed of a substrate 12 having terminal portions 14 and 15i formed thereon, and a permanent magnet 16 for supplying a bias magnetic field.

On the other hand, magnetic pole teeth with a constant pitch period are formed on the surface facing the fixed part 20ij and the movable part 21. Further, the movable part 21 and the fixed part 2o are arranged as shown in FIG. 6, and in particular, the substrate 12 and the fixed part 20ij are inclined at an angle α0, and the permanent magnet 16 and the fixed part 2o are arranged in parallel. . In addition, in the drawings, for convenience of explanation, the movable part 21 is replaced by the fixed part 2.
A travel holding system for holding the vehicle movably along the zero axis is omitted. Further, as shown in FIG. 6(G), the magnetic sensing section 13 is connected to the constant current source 18.16 through the terminal section 14.16i. Fixed resistor 17. Grounding 22. It is assumed that the output terminal 19 is connected to the output terminal 19.

Regarding the detection device of this embodiment configured as above,
The operation will be explained below. In FIG. 5, when the movable part 21 moves in the ±X' direction along the fixed part 2o, the lines of magnetic force from the permanent magnet 16 toward the stator 20 (-Z direction) are aligned with the magnetic poles, as in the conventional example shown in FIG. The direction changes depending on the uneven shape of the tooth □. This situation is shown in FIG. 6, in which 106, 107, 108, 109, and 110 indicate typical lines of magnetic force generated by the permanent magnet 16.

Further, FIG. 7 shows a cross-sectional view of a main part when the magnetic sensing part 13 is at a position where the lines of magnetic force 106 pass.

In this figure, since the bias magnetic field Ho generated by the permanent magnet 16 passes through the magnetically sensitive part 13 obliquely, the magnetically sensitive part 13
, the offset magnetic field Hx in the magnetically sensitive direction (+X direction)
is given, and the strength of the offset magnetic field Hx is lux l = lHo 1sina0...
1) is given. As a result, in the characteristic diagram of the MR element shown in Fig. 2, the conventional image direction of the magnetic field centered on magnetic field 0 can be changed to either 10 or - centered on a constant offset magnetic field Hz'. It can be used in one direction. The same holds true when the magnetic sensing portion 13 is located at a position where the lines of magnetic force 108 or 110 pass. Furthermore, as is clear from the above equation (1), it is possible to freely design the magnetic field by changing the strength of the bias magnetic field lHo1 generated by the IHxlFi permanent magnet or by changing the inclination angle α0 of the magnetically sensitive part. , among the characteristics of the MR element shown in Fig. 2, it is easy to avoid the nonlinear region af and use it in the region s or d where the linearity is relatively good, and as a result, the distortion of the output waveform, which was a problem in the past, can be significantly reduced. This has resulted in a highly accurate detection device.

Next, other embodiments of the present invention will be described with reference to the drawings.

FIG. 8 is a cross-sectional view of a main part of a detection device using an MR element according to another embodiment of the present invention, and (A) is a plan view, (B)
is a sectional view taken along line CC in (A). Note that the same components as in the first embodiment of the present invention shown in FIG. 5 are used, and corresponding parts are designated by the same reference numerals.
The explanation here will be omitted.

This detection device detects the relative position of the movable part 22 when it moves linearly along the fixed part 20, and fixes the substrate 12 and the permanent magnet 16 so that they are integrated into the fixed part 2o. It differs from the first embodiment of the present invention shown in FIG. 5 in that it is tilted by α0 with respect to the first embodiment.

In the detection device of this embodiment configured as described above, an offset magnetic field is applied to the magnetic sensing section 13 by the permanent magnet 16, as in the first embodiment shown in FIG. Therefore, it has been confirmed that the MR element can be used in the relatively linear region (d) of the characteristics of the MR element shown in FIG.

Next, still another embodiment of the present invention will be described with reference to the drawings.

FIG. 9 shows the main parts of a detection device using an MR element according to another embodiment of the present invention, in which (A) is a plan view and (A) is a front view. Note that the same parts as those in the embodiment of the present invention shown in FIG. 5 are given the same reference numerals, and the description thereof will be omitted here.

This detection device detects the rotational position of a rotating gear 24, and includes a gear 24 made of a magnetic material and a substrate 1.
2 and a permanent magnet 16. 7. . 2,238,
□Wow, 2 7. . :)' 7231 is arranged at an angle α0 with respect to the side surface of the gear 24, as shown in FIG. 9, and the rotational position and the entire rotational position are detected by the side surface of the teeth of the gear 24. In this case, the resistance value of the MR element changes depending on the strength of the magnetic field in the directions of arrows ±X in the figure.

The operation and principle of the detection device of this embodiment configured as described above is the same as that of the first embodiment of the present invention shown in FIG. The point is that the movement has changed from the rotational movement to the rotational movement, and the gear 24
By tilting the sensor block at an angle α0 as shown in FIG. 9(A) with respect to the unevenness of the teeth, an offset magnetic field is applied to the magnetic sensing part 13, and the MR characteristics shown in FIG. A region with good linearity is used, resulting in a sine wave-like output with little distortion.

Next, another embodiment of the present invention will be described with reference to the drawings.

FIG. 10 shows the main parts of a detection device using an MR element according to another embodiment of the present invention, and in FIG. It is. Note that the parts are the same as those in the embodiment of the present invention shown in FIG.

The same numbers will be given and explanations will be omitted.

This detection device detects the rotational position of a rotating gear 24, and the sensor block 23 is arranged to be inclined at an angle α0 relative to -1 to the tangent to the outer circumference of the gear 24, as shown in the figure. There is.

Also in the detection device of this embodiment configured as above,
The same effect as the embodiment shown in FIG. 9 can be obtained.

Although each embodiment of the present invention has been described above with reference to the drawings, it goes without saying that the number and shape of the MR elements used therein can be freely designed without departing from the gist of the present invention. .

Further, regarding the method of using the MR element, in each embodiment of the present invention, the constant current source 18. Although the circuit configuration is such as a fixed resistor 17° and ground 22, the circuit configuration is not limited to this, and for example, a circuit configuration using a constant voltage source may also be considered.

Effects of the Invention As is clear from the above explanation, the present invention arranges an MR element in a magnetic field between a permanent magnet and a magnetic pole tooth, and makes the magnetic sensing direction of the MR element at an angle with the surface of the magnetic pole tooth, which was conventionally parallel. By tilting α0, the magnetic field created by the permanent magnet is used not only as a bias magnetic field but also as an offset magnetic field, making it possible to easily obtain a stable offset magnetic field without increasing the number of parts. This results in
It is possible to avoid the nonlinear region of the MR characteristics and use a region with relatively good linearity, and therefore the distortion of the output waveform, which has been a problem in the past, can be significantly improved. As a result, an excellent effect can be obtained in that it is possible to realize a detection device with higher resolution by signal processing the output signal, and a detection device with higher precision can be realized. Also.

The strength of the offset magnetic field is the angle α0? Since it can be freely designed by changing the magnetic field strength of the permanent magnet or by changing the strength of the magnetic field of the permanent magnet, it is possible to easily apply it to MR elements with various characteristics.

[Brief explanation of the drawing]

1(B) is a plan view and a front view showing an example of the MR element used in the conventional example and each embodiment of the present invention, FIG. 2 is a characteristic diagram of the MR element in FIG. 1, Figure 3 (A). (B) A plan view and a sectional view of the main parts showing an example of a conventional detection device using an i'i MR element. FIG. 6(A) is an enlarged sectional view of the main part, FIG. An enlarged sectional view of the main part of the embodiment of the present invention shown in FIG. 6, FIG.
9 and 10 are a plan view and a sectional view of a main part of another embodiment of the present invention, respectively. 12... Substrate, 13... Magnetically sensitive part, 14
．． 15...Terminal section, 16...Permanent magnet, 17...Fixed resistor, 18...Constant current source, 19.Old...Output terminal, 20... Fixed part, 2, 1. 22 Old... Movable part, 23... Sensor part, 24 Old... Gear% 26... Grounding % 1o6
゜IQ7. IQ8, 109, 110... Lines of magnetic force. Name of agent Patent attorney Toshio Nakao and 1 other person τ +X −X Procedural amendment dated March 3, 1986 Mr. Commissioner of the Japan Patent Office 2. Name detection device for invention 3. Person making the amendment Relationship to the case Patent application Colonel Address 1006 Kadoma, Kadoma City, Osaka Prefecture Name (
582) Matsushita Electric Industrial Co., Ltd. Representative Toshihiko Yamashita 4 Agent □ 571 Address Matsushita Electric Industrial Co., Ltd. 6, 1006 Oaza Kadoma, Kadoma City, Osaka Contents of amendment (1) Specification page 9, 11 Correct the "grounding 22" in the row to "grounding 26". (2) Change “Earth 22” in the 12th line of page 14 to “Earth 2”.
6". (3) Drawings Figure 6 M, Figure 8 M, Figure 9 B and Figure 1
Correct each figure 0 as shown in the attached sheet. ■ Figure 5 (C) Figure 8 (8) Figure 9 Figure 1 (B) (8) Figure O

Claims (1)

[Claims] The seventh means includes a ferromagnetic thin film resistance element having a magnetic anisotropy effect, and a first means and a second means for performing relative movement while maintaining a constant interval. The second means includes a permanent magnet that applies a magnetic field 4 to the ferromagnetic thin film; The resistance element is arranged in a magnetic field between the permanent magnet and the tooth-shaped unevenness, and arranged so that the magnetic field sensing direction of the ferromagnetic thin film resistance element is in the direction of the relative motion, and the ferromagnetic A detection device characterized in that the thin film surface of the thin film resistance element is arranged at a constant inclination angle with respect to the surface of the magnetic material on which the unevenness of the second means is formed.