JPH01178870A - Detecting device of rotation - Google Patents

Abstract

PURPOSE:To maintain a prescribed distance between a magnetoresistance element and a substance to be measured, by providing a base which is maintained at a prescribed distance to this substance by its contact with the substance, and the magnetoresistance element which is formed on this base. CONSTITUTION:A recessed part 11a is formed in a base 11 made of Si, and a magnetoresistance element 12 is formed on the bottom surface of the recessed part 11a. A substance 13 to be measured, which is a rotary body on the outer peripheral surface of which N-poles and S-poles are formed sequentially, is in contact with the base 11 at the opposite ends of the recessed part 11a. Accordingly, the part of the substance 13 facing the recessed part 11a intrudes into the recessed part 11a. In a first embodiment thus constituted, a spacing distance (d) is maintained to be prescribed, since the base 11 and the substance 13 to be measured are in contact with each other at the opposite ends of the recessed part 11a and since Si constituting the base 11 has a high abrasion resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a rotation detection device that detects the rotation of an object to be measured using a magnetoresistive element.

[Summary of the invention]

In the rotation detecting device as described above, the present invention maintains a constant distance between the base and the object to be measured by bringing them into contact with each other, and forms the magnetoresistive element on the base so that the magnetoresistive element can be fixed. This reduces wear.

[Conventional technology]

A rotation detection device using a magnetoresistive element is used to detect the rotation of a recording/reproducing head of a VTR. In such a rotation detection device, the magnetic resistance element and the object to be measured are used in contact in order to maintain a constant distance between the rotation detection device and the object to be measured and to maintain constant detection sensitivity. There are cases. Regarding magnetoresistive elements, Utility Application No. 60-433
There is No. 79.

However, when the magnetoresistive element and the object to be measured are brought into contact,
The magnetoresistive element is severely worn out. As a countermeasure against this problem, it has been considered to cover the magnetoresistive element with a protective film.

As such a protective film, coating type thermosetting resin, silica glass, and further vapor-deposited SiO□, Aha3, etc. are considered.

[Problem to be solved by the invention]

However, it is not possible to obtain sufficiently high hardness with coated thermosetting resins or silica glass. On the other hand, vapor-deposited SiO□ and A1□03 have high hardness, but cracks occur when vapor-deposited for a long time, making it difficult to increase the thickness.

Therefore, in conventional rotation detection devices, the magnetoresistive elements tend to wear out.

[Means to solve the problem]

The rotation detection device according to the present invention includes a base body 11 that is kept at a constant distance from the object to be measured 13 by contact with the object to be measured 13, and a magnetoresistive element 12 formed on the base body 11. They are equipped with each.

(Function) In the rotation detection device according to the present invention, the distance between the base 11 and the object to be measured 13 is kept constant by contacting them, and the magnetoresistive element 12 is formed on the base 11. Therefore, the distance between the magnetoresistive element 12 and the object to be measured 13 is also kept constant.

[Embodiments] Hereinafter, first to fourth embodiments of the present invention will be described with reference to FIGS. 1 and 2.

FIG. 1A shows a first embodiment. In this first embodiment, a recess 11a is formed in a base 11 made of Si, and a magnetoresistive element 12 as shown in FIG. 2 is inserted into the recess tta.
is formed on the bottom of the

Note that the recessed portion 11a can be easily formed by a lithography process and an etching process that are commonly used in manufacturing semiconductor devices.

On the other hand, the object to be measured 13, which is a rotating body in which a north pole and a south pole are sequentially formed on the outer peripheral surface, is in contact with the base body 11 at both ends of the recess 11a, as is clear from FIG. 1A. . Therefore, the portion of the object to be measured 13 facing the recess 11a is inserted into the recess 11a.

However, as is clear from FIG. 1A, the magnetoresistive element 1
2 and the object to be measured 13 are not in contact, and the distance d between them is
is about 50 μm at maximum.

In the first embodiment, the base 11 and the object to be measured 13 are in contact with each other at both ends of the recess 11a, and the base 1
Since Si constituting 1 has high wear resistance, the separation distance d is kept constant.

Therefore, even though the detection sensitivity is held constant,
Even if the magnetoresistive element 12 is not covered with a protective film, the magnetoresistive element 12 will not wear out.

Although the step of forming the recess 11a in the base body 11 is increased compared to the conventional example described above, on the contrary, the step of forming a protective film for the magnetoresistive element 12 is not necessary.

As a result, the overall manufacturing cost of the rotation detection device does not change significantly.

FIG. 1B shows a second embodiment. In this second embodiment, a convex portion 11b is formed on the base body 11 instead of the concave portion 11a, and the separation distance d is maintained constant by the object to be measured 13 coming into contact with the convex portion 11b. Except for this, the second embodiment has substantially the same configuration as the first embodiment described above.

Therefore, even in such a second embodiment, the same effects as in the first embodiment can be achieved.

FIG. 1C shows a third embodiment. This third embodiment has substantially the same configuration as the first embodiment described above, except that the recess 11a is also formed in a meander shape along the meander-shaped magnetoresistive element 12. are doing.

Therefore, in the third embodiment, even if the width of the recess 11a is narrow and the radius of the object to be measured 13 is small, the magnetoresistive element 12 and the object to be measured 13 can be separated by a constant distance d. . Therefore, this third embodiment can also achieve the same effects as the first embodiment.

FIG. 1D shows a fourth embodiment. In this fourth embodiment, the object to be measured 13 enters the recess 11a to a deeper position than in the first example, and the magnetoresistive element 12 and the object to be measured 13 are in contact near the center of the recess 11a. There is.

However, also in this fourth embodiment, the base body 11 and the object to be measured 13
are in contact with each other at both ends of the recess 11a. Therefore,
The magnetoresistive element 12 is not worn further than the state shown in FIG. 1D.

Therefore, this fourth embodiment can achieve substantially the same effects as the first embodiment.

〔Effect of the invention〕

In the rotation detection device according to the present invention, since the distance between the magnetoresistive element and the object to be measured is kept constant, the wear of the magnetoresistive element is small.

[Brief explanation of the drawing]

1A to 1D show the first to fourth embodiments of the present invention, respectively, and the cross-sectional view taken along the line I-1 in FIG. FIG. 3 is a plan view of a magnetoresistive element. In addition, in the symbols used in the drawings, 1t----------1.
---111----- Magnetoresistive element 13----
-----------It is the object to be measured.

Claims (1)

[Scope of Claim] A rotation detection device that detects the rotation of an object to be measured using a magnetoresistive element, comprising: a base that maintains a constant distance from the object by coming into contact with the object; , and the magnetoresistive element formed on the base.