JPS6373114A - Magnetic sensor - Google Patents

Abstract

PURPOSE:To improve the quality and the precision in detection and to facilitate manufacture by simplifying the structure, by a method wherein a pattern formed of a thin film of ferromagnetic material is provided on a substrate made of non-conductive material and a protection film of prescribed material is provided in the peripheral edge part thereof. CONSTITUTION:Within the sphere of the action of a magnetic field of a rotary drum 1 which is so formed that NS magnetic poles appear alternately on the surface, a magnetism-sensitive element 3 is so disposed that it faces the magnetic pole surface of the drum 1 and can move relatively with a prescribed gap therefrom. Moreover, a pattern 5 formed of a thin film of ferromagnetic material is provided on a substrate 4 made of non-conductive material, a protection film 6a of non-magnetic inorganic material is provided partially in the peripheral edge part of the pattern 5, and further a protector 7 formed of non-water- permeable material is provided on the pattern 5 and the protection film 6a. By this constitution, a gap between the drum 1 and the magnetism-sensitive element 3 is reduced and thereby the precision in detection is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Applications] The present invention relates to an improvement in a magnetic sensor that utilizes the so-called magnetoresistive effect in which electrical resistance changes in a magnetic field to convert it into an electrical signal and detect a single position. It is something.

[Conventional technology]

In recent years, highly accurate position sensors or rotation sensors have become necessary in the fields of OA and FA.

Position detection of NC machine tools, robots, etc., OA equipment.

It is commonly used in various servo motors, rotary encoders, etc. used in VTRs, etc. Also OA.

With the advancement of FA technology, the speed of the above sensors has also increased.

There is a growing demand for high confidence. Under these circumstances, 9 For example, conventionally, most rotation sensors have been optical, but since they use semiconductor elements such as photocells and LEDs as components, they have insufficient stability against temperature changes. However, it also has the drawbacks of a large number of component parts and a complicated structure. For this reason, a magnetic type that utilizes the magnetoresistive effect was developed, and has high detection accuracy.
Since it is stable against temperature changes, it is gradually being applied in various fields.

FIG. 3 is a perspective view schematically showing an example of the rotation sensor. In the same figure, reference numeral 1 denotes a rotating drum which rotates around a rotating shaft 2 in the direction of the arrow.

A magnetic coating film, such as γ iron, is provided on the outer peripheral surface of the rotating drum 1, and magnetized so that NS magnetic poles appear alternately. The number of magnetized magnetic poles is appropriately selected to be several hundred or more depending on the detection accuracy. Therefore, a minute magnet with an extremely narrow magnetic pole pitch is formed. Next, 3 is a magnetic sensing element, and a plurality of magnetoresistive elements are provided on the surface.

It is arranged to face the magnetic pole surface of the rotary drum 1 and within a range where the magnetic field of the micromagnet acts, with a predetermined gap therebetween. With the above configuration, an electric signal is generated from the magneto-sensitive element 3 provided with the magnetoresistive element by 10 rotations of the drum, so that it is possible to detect 2 rotation speeds and 1 position.

C Problems to be Solved by the Invention] FIG. 2 is an enlarged sectional view of a main part of the magnetic sensing element 3 in FIG. 3, and the same parts are designated by the same reference numerals as in FIG. 3.

In the figure, a pattern 5 made of a thin film of a ferromagnetic material such as permalloy is provided on a glass substrate 4, and above it a protective film 6 made of 5ift and another protective film 7 made of PIQ resin are provided. The protective films 6 and 7 each have the function of preventing damage to the pattern 5 due to external forces and infiltration of moisture. In order to improve the detection accuracy of magnetic signals, it is necessary to minimize the distance between the magnetic pole surface and the magnetic sensing element.
In particular, this interval is particularly small in those requiring high resolution. Generally, the distance is 100 μm or less, so if the rotating drum 1 and the magnetic sensing element 3 are brought into contact with each other inadvertently during adjustment of the mounting position, the protective film 6.7 may be damaged.
Not only will it peel off, but in extreme cases, the internal pattern 5 may also be damaged or disconnected. For this reason, a foil 8 made of a non-magnetic material such as stainless steel or Nb is pasted with an adhesive 9 above the protective film 6.7 to prevent damage to the pattern 5.

However, it takes a long time to form the protective film 6.7, and furthermore, the work of pasting the foil 8 on the outside of the protective film 6.7 with the adhesive 9 is extremely complicated.

There is a problem that work efficiency is significantly reduced.

Further, a foil 8 is further formed on the protective films 6 and 7.
There is a problem in that the gap becomes large and causes a decrease in the detection accuracy of the magnetic sensing element 3.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a magnetic sensor that solves the problems existing in the prior art as described above, has high quality and detection accuracy, has a simple structure, and is extremely easy to manufacture.

[Means for solving problems]

In order to solve the above problems, one aspect of the present invention is as follows.

Within the range in which the magnetic field of a magnet body formed so that NS magnetic poles appear alternately on the surface of A9 acts, the rf! !
, in a magnetic sensor equipped with a boron element.

B. A pattern made of a thin film of ferromagnetic material is provided on a substrate made of non-conductive material.

C1 A protective film made of a non-magnetic inorganic material is partially provided on the periphery of this pattern.

D. Another protective film made of a water-impermeable material is provided above the pattern and the protective film.

This technical method was adopted.

[Effect]

With the above structure, the pattern can be protected by the protective film having relatively high mechanical strength even if it comes into contact with, for example, a rotating drum.

Also against moisture intrusion.

It is completely protected by a protective membrane made of water-impermeable material.

〔Example〕

FIG. 1 is an enlarged sectional view of main parts showing an embodiment of the present invention,
Identical parts are designated by the same reference numerals as in FIG. 2 above. In the figure, 6a is a protective film made of StO□, which is partially provided at the periphery of the pattern 5. When forming the protective film 6a, it is convenient to mask the middle part of the pattern 5, for example. The thickness of the protective film 6a is preferably formed slightly thicker than the conventional one, but if it is too thick, the gap between the protective film 6a and the magnet body (for example, the rotating drum 1 in FIG. 2) becomes large, which is undesirable. 5-20μm
The thickness of the protective film 6a is preferably less than 0.5 μm, preferably 3 to 10 μm.
For example, the effect of protecting the pattern 5 from contact or abutment with the rotating drum 1 etc. shown in FIG.
If it exceeds 0 μm, it is not preferable because it increases the gap with the magnet and lowers the sensitivity. Next, another protective film 7 made of PIQ resin is provided above the pattern 5 and the protective film 6a to provide a moisture-proofing effect.

Next, the thickness dimensions of the above constituent materials are shown below.

Glass substrate 700μm Permalloy pattern 0.05μm 5in, protective film 4μm PIQ resin protective film 3μm With the above configuration, an element with external dimensions of, for example, 13 m x 5.5 t* is manufactured, and a gap of 50 μm is formed between it and a rotating drum of 30 nφ x 10 fi. As a result of assembling the rotation sensor through the machine, the work efficiency was significantly improved compared to the conventional one. Moreover, no damage occurred to pattern 5 during the gap adjustment work.

In this embodiment, an example is shown in which the magnet body is a rotating drum, but the T61 stone body may be in the form of a flat plate, and may be disposed so as to be movable relative to the angry magnetic element.

Further, the material forming the substrate is not limited to glass, but may be other non-conductive materials or electrically insulating materials. The non-magnetic inorganic materials forming the protective film include SiO,
(7) In addition, 's i N, Alt 03, etc. can be used. What is the material that forms the pattern?

In addition to Fe-Ni alloys such as permalloy, Ni-Co
Ferromagnetic materials such as alloys can be used. Furthermore, the materials forming the protective film used for the purpose of moisture proofing are:
Of course, water-impermeable materials other than PIQ resin can be used.

〔Effect of the invention〕

Since the present invention has the structure and operation as described above,
You can expect the following effects.

+11 Since the gap between the magnet body and the magnetic sensing element can be significantly reduced, detection accuracy can be dramatically improved.

(2) Since the structure is simple, one-work efficiency is greatly improved compared to conventional chisels.

(3) It is possible to completely eliminate defects such as wire breakage during adjustment work, so both quality and yield are significantly improved.

[Brief explanation of the drawing]

FIG. 1 is an enlarged sectional view of main parts showing an embodiment of the present invention. FIG. 2 is an enlarged sectional view of a main part of a conventional sensor, and FIG. 3 is a perspective view schematically showing an example of a rotation sensor. rotating drum, 3: magnetic sensing element, 4 glass substrate, 5: pattern, 6. 6a, 7: Protective film.

Claims (7)

[Claims] (1) Within the range in which the magnetic field of a magnet body formed such that NS magnetic poles appear alternately on its surface acts, a magnetic sensing element is provided that faces the magnetic pole surface of the magnet body and is movable relative to the magnetic pole face of the magnet body through a predetermined gap. In a magnetic sensor equipped with
A magnetic sensor characterized in that a protective film made of a non-magnetic inorganic material is partially provided on the periphery of the pattern, and another protective film made of a water-impermeable material is provided above the pattern and the protective film. . (2) The magnetic sensor according to claim 1, wherein the magnet is a rotating magnet. (3) Claim 1 in which the non-conductive material is glass
The magnetic sensor according to item 1 or 2. (4) Ferromagnetic material is Fe-Ni alloy or Ni-C
The magnetic sensor according to any one of claims 1 to 3, which is an o-based alloy. (5) The thickness of the protective film made of non-magnetic inorganic material is 0.5~
The magnetic sensor according to any one of claims 1 to 4, which has a diameter of 20 μm. (6) The magnetic sensor according to any one of claims 1 to 5, wherein the nonmagnetic inorganic material is SiO_2. (7) The magnetic sensor according to any one of claims 1 to 6, wherein the water-impermeable material is a PIQ resin.