JPS5944673A - Magnetism detector - Google Patents

Abstract

PURPOSE:To obtain a magnetism detector whose detecting function is raised, by constituting a housing by use of a magnetic metal having a high magnetic permeability and performing magnetic shielding to a magneto-resistance element. CONSTITUTION:A flat housing 36 which cuts a corner of the left and right upper end part and has a hexagonal shape in elevation view is obtained by forming a magnetic metallic plate such as permalloy, etc. by a press, and an opening part 36a provided on the upper face is closed by a protecting plate 37 consisting of a thin film made of a non-magnetic metal such as phosphor bronze, etc. Magneto-resistance elements 32, 33 are provided in parallel on the left and right so as to have a suitable interval to the protecting plate 37. A sensor unit 30 obtained by forming two elements 32, 33 on a ferromagnetic material 39 such as ferrite, etc. is fixed onto the upper face of a substrate 38 consisting of an insulating material. In this way, since the magneto-resistance element is magnetically shielded by the housing made of a magnetic metal, it is scarcely influenced by an external magnetic field, and magnetism can be detected with high sensitivity through the protecting plate 37 of a non-magnetic material.

Description

DETAILED DESCRIPTION OF THE INVENTION Regarding the id magnetic detector of the present invention, the song ``Kei-1-21'' relates to a magnetic detector using a magnetoresistive element whose resistance jJ changes according to changes in the magnetic field.

InE3b, In5b-NiSb, Engineering II
Caryai Tau J of AS etc./! Semiconductor or I with high IC
re Ni-Co, Ni, -Fe, N1-
Fe-c.

Ferromagnetic materials such as ferromagnetic materials have the property that their resistance value increases when exposed to a full magnetic field, and the LIB magnetic detector, which makes full use of this property to detect the presence of magnetism, the presence of magnetic materials, and the presence of transfer, has been put into practical use. It's been changed.

FIG. 1 is a schematic diagram for explaining the principle of detecting the approach and displacement of a magnetic substance. Identical direct resistance elements 12 and 13 made of Sb, for example, are arranged on one side of the magnetic pole end face of a permanent magnet (an electromagnet may also be used). Their respective positions are determined so that they are equally magnetic.

Elements 12 and 13 are connected in series, and a voltage V is applied between both terminals of this series circuit, and the pixel element σ) (χM
The point is set as the output terminal 14.

Then, the magnetic object 15 approaches this detector from the element 131tll+ and moves to l21i11 Mi! When the object 15 approaches the element 1311111, magnetic flux concentrates on the element 1311111, and the resistance value of the element 13 increases, while the resistance value of the element 12 decreases, and the potential V14 of the output terminal 14 becomes lower than that of the object 1311111. The V/2 construction before approaching No. 15 also turned into a hatake.

When the subject 15 approaches the element 12, the resistance value is reversed, and the V/2 area of +4 becomes lower. By monitoring the potential of v14 in this way, it becomes possible to detect the approach and movement of the magnetic body.

Now, FIG. 2 is an elevational view showing the structure of a conventional magnetic detector. The flat casing 26, which has a hexagonal shape when seen in elevation with the left and right upper edges cut off, is a plastic molded product, and the opening 26b provided on the top surface is closed with a protective plate 27 made of a thin film made of Veri IJ Umu copper. I am doing r. The protective plate 27 is the housing 26
It is integrally molded with VC, and its outer surface is 11]1'
All parts are chrome plated to improve wear resistance. Magnetoresistive element 2 is placed so as to have an appropriate gap with this protection plate 27.
2.23 has 31F on the left and right. That is, on the upper surface of the substrate 28, two elements 2 are placed on a ferromagnetic material 29 such as ferrite.
2.23 The fully formed sensor unit) 2Q is attached at the same time, and the sensor unit 20 is attached to 1ff11 on the periphery of the board 28.
The lower surface of the annular spacer 25 that surrounds the whole area is attached at the same time.
Place Ueda J of the spacer 25 at 1'a of the opening 26a.
It is fixed to the inner periphery or the periphery of the retaining hlJ board 27. One magnetic pole ψ of a cylindrical magnet 21 is mounted on the bottom surface of the 5vc board 28.
jIt was a tie in terms of quality. Element 22.23 drawer 1c
The leads are the conductors formed on the board 28 and the leads are passed through the board 28! : It is once placed on a terminal plate attached to the inner wall of the housing 26 using a 1ζ conductor, and is connected to a lead #jl 24 that completely penetrates the bottom plate 26b of the housing 26. The bottom plate 26b is molded separately from the other parts of the housing 26 and is sealed after being assembled. Although not specifically shown in the drawings, the flute body 26 is filled with resin such as epoxy.

Now, since the magnetoresistive elements 22 and 23 are sensitive to magnetism, they are naturally sensitive to disturbance magnetic fields (external magnetic field noise) which it is not desirable to detect. For example, if it is installed near a transformer with a large leakage magnetic flux, all the leakage magnetic flux outside the VCit will be captured and a large noise signal will be generated, making it impossible to detect the minute signal generated by the approach of a minute magnetic body.

The main purpose of Akira was to take into consideration this situation, and to create a case using a magnetic metal with high magnetic permeability to provide a magnetic shield for the magnetoresistive element. The overall purpose is to provide a highly capable broiling air detector.

The present invention will be described in detail below based on drawings showing embodiments thereof.

FIG. 3 is a vertical plan view showing the structure of the magnetic detector according to the present invention. The flat casing 36, which has a hexagonal shape when viewed from above with full-width edges at the left and right upper ends, is formed by press-molding a magnetic metal plate such as permalloy (for example, JIS PC), and the opening 36a provided on the top surface is Thin film made of non-magnetic metal such as phosphor bronze (
Closed with a protective plate 37 (thickness O, about 1 mm)
ing. The protection plate 37 and the housing 36 are soldered to each other for fixation and electrical continuity. The material of the housing 36 is a magnetic metal and is not limited to permalloy. The thicker the plate thickness is, the better for magnetic shielding, and the ideal is 0.3 or more, but it is best to avoid compromising on the appropriate thickness for the sake of workability during press forming. do not have. Protective plate 37
Since magnetic material and magnetism are detected through this part, it is necessary to use a non-magnetic material, and the surface thereof may be plated with chrome to improve friction resistance, if necessary.

Magnetoresistive elements 32 and 33 are arranged side by side on the left and right across the protective plate 37 and at appropriate intervals. A sensor unit 30 consisting of two elements 32 and 33 completely formed on a ferromagnetic material 39 such as ferrite is fixed on the top of the substrate 38 made of an insulating material.
The lower surface of the annular spacer 35 that surrounds the housing is fixed, and the upper surface of the spacer 35 is fixed to the periphery of the opening 36a of the housing 36 or to the periphery of the protective plate 37. Historically, one pole end face of a cylindrical permanent magnet (an electromagnet may be used) 31 for biasing is fixed to the bottom surface of the substrate.

The elements 32 and 33 are connected in a row as shown in FIG.
! These lead wires 34 are connected to the terminal board attached to the inner wall surface of the housing 36 using a conductor, and connected to the lead wires 34 that are connected to the bottom plate 36'b of the housing 36. Needless to say, it can be subjected to the same type of binding as that of the previous one.

It is preferable that the housing 36 be grounded in order to prevent discharge, which will be described later. The bottom plate 361) is formed separately from the other parts of the housing 36 and is made of n1ζ magnetic metal, but is sealed after the internal parts described above are assembled. Bottom plate 36
Since b is far from the magnetoresistive elements 32 and 33, a conventional one made of plastic may be used.

The inside of the casing 36 is filled with #4 resin (not shown) such as epoxy.

In the case of the product of the present invention as described above, since the magnetoresistive element is magnetically shielded by the magnetic metal housing, it is not affected by most of the disturbance, and is protected against non-11-like 4F bodies. Magnetic substances and magnetism can be detected with high sensitivity through 37 vaginal plates. In addition, even if the amplification of K (the body is made of metal, electrostatic induction can be completely prevented and the high priest's width) is continued by 4 and 1x, false detection due to electrostatic induction can be prevented by lv5+J-.

- In addition, in the case of industrial applications where the protection plate 37 is attached to banknotes for identification, static electricity is generated due to friction in conventional plastic plates, which charges the casing.
Do not discharge into the electrical circuit connected to the resistive element or the
There was an attempt to destroy 2, but it was made of metal! With the product of this invention, there is no such abuse when using the body.

In addition, when comparing the product of the present invention and the conventional product, there is a difference of 0.5 mm in the casing.
In the case of the product of the present invention using permalloy PC fiber with high magnetic permeability of G-, even in the worst case, the noise signal Q generated by the disturbance A1B field can be reduced to about 1/3 of the conventional product.

As described above, the 6E & Qi detector according to the present invention houses a magnetoresistive element in a case in which part or all of it is made of a magnetic metal area, so it is possible to perform high-sensitivity detection while completely avoiding the effects of disturbance magnetic fields. Therefore, it is possible to realize a magnetic detector that is free from problems such as erroneous detection due to magnetic induction and destruction due to electrostatic discharge.

Note that the present invention uses Ni-C.

The present invention can also be applied to a single device using a strongly bi-enhanced magnetoresistive element such as the following.

79 Drawing 1 Simple convexity 1. 1 is an explanatory diagram of the detection principle of a magnetic detector, FIG. 2 is an Mz: +1:fi blood diagram of a conventional magnetic detector, and FIG. 3 is a vertical view of the magnetic detector of the present invention.

30...Sensor unit 31...Permanent magnet 32.3
3... Magnetoresistive element 36... Housing 37... Protective plate 38... Substrate patent applicant Sanyo Electric Co., Ltd. and one other representative Patent attorney Noboru Kono Momo1 Figure 2.9 Momo2 Flash Juri 1

Claims (1)

[Claims] 1. 4ifi inside a housing partially or entirely made of magnetic metal
A direct air detector that is characterized by the fact that it houses an air resistance element.