JPS59138973A - Body detection system - Google Patents

Abstract

PURPOSE:To detect whether a body is present or not and its passing by fitting an amorphous magnetic body to the body to be detected and detecting a high- frequency electromagnetic field produced when an alternating electromagnetic field is applied thereupon. CONSTITUTION:The ribbon type amorphous magnetic body is fitted previously to some part of the body to be detected, e.g. a high-grade article of clothing, food, etc. Then, the >=200KHz alternating electromagnetic field operates thereupon and tertiary and quintic high-frequency electromagnetic fields, etc., are detected produced by the magnetic body to detect whether the body is present or not. Thus, shoplifting at a department store, supermarket, etc., is prevented effectively.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an object detection device using a magnetic material.

Conventionally, this type of method using permalloy ribbon was well known, but permalloy has low mechanical hardness and is easily deformed, so it is difficult to attach it to objects.
At the time of andlinO, the magnetism of A deteriorates, and the detectability may deteriorate, which has become a serious problem.

In other words, such object detection methods are applied to, for example, high-end clothing, books, and food products, and are partially put into practical use in department stores and supermarkets to prevent shoplifting. If the magnetism deteriorates due to stress, etc., even if the detection device installed at the entrance/exit is operating normally, the detected signal generated from the permalloy ribbon will become weak and it may not be possible to detect shoplifting. did.

The present invention provides a completely new object detection method that overcomes these drawbacks of the prior art.

That is, in the present invention, an amorphous magnetic material is attached to a part of the object to be detected, an alternating electromagnetic field of 200 kl-1z or more is applied, and high frequencies such as 3rd or 5th order generated from this magnetic material are detected, It detects the presence or absence of an object.
Since the amorphous IT and FL materials have great mechanical strength and are difficult to deform due to external forces, they have the characteristic that detection errors do not occur.

In this case, almost any amorphous material is effective as long as it is magnetic, but from the point of view of magnetic flux density, the generally used Fe-based material, which is older and higher than G, gives better results. is obtained.

In addition, looking at the relationship with magnetostriction, the magnitude of the saturation magnetic flux for the amorphous material as a whole is 7) -5X10-' to -5X10
'Those between ' showed relatively good results.

In addition, according to the results of evaluating COM amorphous materials in particular, materials close to λ-0 have particularly good performance, and including this, +1x10'≦234-1X.

The present invention will be explained below based on examples.

Example 1 Using various F-based amorphous materials approximately 20μ thick, 4mm wide, and 100mm long, an external magnetic field of 1kt-1z is applied to detect objects in a method that detects the third-order high-frequency magnetic field component. As a result, it was found that the detection output was low and not effective when the saturation magnetic flux density was less than 4KG, but when the saturation magnetic flux density exceeded 4KG, sufficient detection output was obtained, and it was confirmed that As a result, detection errors did not occur in even one out of 100 cases with amorphous materials. This can be said to be extremely excellent considering that there were 7 detection errors out of 100 when Permalloy was used.

Example 2 As in Example 1, the thickness was approximately 12 μm and the width was 2 mm.

When we investigated the relationship between magnetostriction properties using an amorphous material with a length of 80 mm, we found that the closer the magnetostriction value is to zero, the fewer detection errors occur. It has been found that any material that falls between 5x10-' and -5,xlo-' can be used.

Example 3 In the same manner as in Example 1, using a Co-based amorphous material with a thickness close to 30μ, an investigation was performed at a frequency of 5kl-1z, and the results showed that the magnetostriction was particularly close to zero -lX10<λS≦+lX1
In the range of 0.0, it was found that not only there were no detection errors, but also that the 3rd or 5th order high frequency output for the detected object could be greatly increased, and it was found that it was useful as a detection device even if it was an extremely large one. .

Although the present invention is theoretically possible even if the frequency is low, in practice it is preferable to operate at a frequency of 200H2 or higher from the viewpoint of output, so the frequency to be used is defined in this manner here.

Procedural amendment June 16, 1982 Patent application No. 12232 Title of the invention Person making the amendment to the object detection method Case and relationship Patent applicant address 2-1-2 Marunouchi, Chiyoda-ku, Tokyo Name (5
08) Hitachi Metals Co., Ltd. Telephone: Tokyo 03-284 4642 "Detailed Description of the Invention" column of Book III.

Contents of amendments 1. The statement in the "Detailed Description of the Invention" column of the specification is corrected as follows.

(1) r200 k H2J on page 3, line 2 of the specification
Corrected to 200Kz J.

(2) On page 4, line 5 of the same book, “Thickness is about 20μ, width is 4mm,
Correct "length 100 mm" to "thickness approximately 20 μm, width 4 mm, length 100 m 1 TIJ.

(3) “Thickness is approximately 12μ,
2mm wide and 80mm long" to 12μm thick and 2m wide.
m, and the length is corrected to 80n+n+J.

(4) "Thickness 30μ" in page 5, line 5 of the same book is 1 - thickness 3
Correct it to 0 μm.

”−

Claims (1)

[Claims] 1. Detecting a high-frequency electromagnetic field generated when a ribbon-shaped amorphous material body is attached to a part of an object to be detected and an alternating electromagnetic field with a frequency of 2001-1 z or more is applied to it. An object detection method characterized by detecting the presence or absence of an object through two passages. 2. An object detection method according to claim 1, characterized in that the amorphous material used is an amorphous material of Fe-base BS 4 KG or higher. 3. In claim 1, the amorphous material used is particularly magnetostrictive.
An object detection method characterized by using an amorphous material having a hardness of Hv400 or more. 4. In claim 3, 1×10 ≧λ
An object detection method characterized by using a Co-base amorphous material of -1xio'.