JP2001194438A - Magnetic sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a magnetic sensor, in which a coil can be mounted only by inserting an air-core coil into a core part, whose manufacturing process is simple and low-cost and in which an exciting magnetic flux does not have adverse effects on a magnetic body as an object to be detected. SOLUTION: The magnetic sensor is provided with a core body 1 for the magnetic sensor, which comprises magnetic gap parts 24, 25 facing toward mutually different directions. The magnetic sensor is provided with a coil 17 for excitation, which is wound so as to generate magnetic flux in the magnetic gap parts 24, 25. The magnetic sensor is provided with coils 15, 16, for detection, which detect a change in the magnetic flux generated by the coil for excitation. The two magnetic gap parts 24, 25 are composed of two core parts which form a pair. One among the two core parts 13, 14 is used as the coil-winding part. One among the coil for excitation and the coils for detection is wound on the core part. A core part 18, for coil winding, is formed so as to protrude in the magnetic intermediate part with reference to the two magnetic gap parts. One each of a coil is attached to the coil winding part and the core part for coil winding.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic sensor for identifying a magnetic material provided on an object to be detected based on a change in magnetic flux according to the magnetic permeability of the object to be detected. Applicable.

[0002]

2. Description of the Related Art In recent years, there has been a tendency to increase the coercive force of a magnetic stripe of a magnetic card in order to improve the reliability of recorded data in the magnetic card. Up to now, cards with various coercive forces are available. Therefore, read the data recorded on these cards,
A card reader for recording data is required to have a function of recording data with an appropriate current value according to magnetic cards having various coercive forces.

[0003] Accordingly, the present applicant has proposed that the coercive force of a magnetic material
Focusing on the correlation with the magnetic permeability, by detecting the change in magnetic flux depending on the magnetic permeability of the magnetic stripe of the card,
We have developed and applied for a patent for a differential magnetic sensor that identifies the coercive force of a card. One of them is described in the specification and drawings of Japanese Patent Application No. 11-161876. Hereinafter, the outline and operation principle of this differential type magnetic sensor will be described.

FIG. 6 shows an example of a detecting section of a differential magnetic sensor, and FIG. 7A shows a core body of the detecting section. In FIG. 6, the detection unit of the differential magnetic sensor generates a magnetic flux in the magnetic sensor core body 1 having two magnetic gaps 24 and 25 having different directions and the two magnetic gaps 24 and 25. An excitation coil 17 wound as described above, and two detection coils 15 and 16 wound to detect a change in magnetic flux generated by the excitation coil 17 are provided. As shown in FIG. 7A, the magnetic sensor core 1 includes a flat core 10 and the flat core 10.
Two Ls projecting symmetrically from one side in opposite directions
This is a core body having a p-shaped cross section, which is formed by the letter-shaped core portions 13 and 14. The two magnetic gaps 24 and 25 are constituted by both ends 11 and 12 of the flat core 10 and the two L-shaped cores 13 and 14. The two detection coils 15 and 16 are wound around the roots of the two L-shaped core portions 13 and 14, respectively. The exciting coil 17 straddles the two magnetic gaps 24 and 25,
Further, it is wound around the detection coils 15 and 16 located in the magnetic gaps 24 and 25.

The two magnetic gaps 24 and 25 are open at their respective ends, that is, at both ends in the vertical direction in FIG. 6 of the magnetic sensor core 1. In this way,
The main part of the magnetic sensor is symmetrical with respect to the center of the core 1 in the vertical direction. The above two magnetic gaps 2
4 and 25, one of the magnetic gaps 24 faces the passage of the detection target such as a magnetic card, and the magnetic gap 2
One end 11 of the plate-shaped core portion 10 and the tip end of the L-shaped core portion 13 form a sliding surface on which the object to be detected slides. Ferrite or the like is used as a material of the core body 1.

[0006] The above-described detection unit including the core 1 and the coil is put in a case, and resin is poured into the case and fixed. The sliding surface of the detection unit is polished to expose the sliding surface from the case, thereby completing the magnetic sensor. This magnetic sensor can be used as a card coercive force identification sensor or the like.

By passing a current through the exciting coil 17, magnetic fluxes of the same magnitude are generated in the two magnetic gaps 24, 25. The two detection coils 15 and 16 are connected so that differential outputs of both of these coils can be obtained. Therefore, if the object to be detected such as a magnetic card is not in sliding contact with the sliding surface, the differential output is zero. Now, when an object to be detected is conveyed and its magnetic stripe portion or the like slides on the sliding surface, a difference occurs between a magnetic flux passing through one L-shaped core portion 13 and a magnetic flux passing through the other L-shaped core portion 14. , A differential output is obtained from the two detection coils 15 and 16. Thus, it can be determined that the detected object is in sliding contact with the sliding surface. Further, since the differential output changes in accordance with the coercive force of the magnetic material used in the object, the magnetic material used in the object is highly retained in accordance with the magnitude of the differential output. It can be determined whether the material is a magnetic material or a low coercive force material. Therefore, when the object to be detected is a magnetic card, it can be determined whether it is a high coercive force card or a low coercive force card.

As another example of the core body used in the detecting section of the differential type magnetic sensor, one having the form shown in FIG. 7 (b) has been considered. This is an H-shaped core body 31. The two core parts 41, 43 on one side of the H-shaped core body 31 which are parallel to each other and the two core parts 42, 42 on the other side are parallel to each other.
Magnetic gaps 54 and 55 are formed between the two magnetic gaps 44, respectively, and are located between the two magnetic gaps 54 and 55, and
It has a core connecting portion 40 connecting the core portions 41, 43 and 42, 44. Each of the two core portions 41,
43 and 42, 44, for example, the core part 4
A detection coil is wound around each of the coils 3 and 44, and a part of these detection coils is located in the magnetic gaps 54 and 55 with the core connecting portion 40 interposed therebetween. Further, the magnetic gap 5
The excitation coil is wound from outside the detection coil over the sections 4 and 55. Such an H-shaped core body 31
The detection unit of the differential type magnetic sensor using
In the same manner as in the conventional example shown in (a), the presence / absence of the object to be detected and whether the magnetic material of the object to be detected is a high coercive force material or a low coercive force material can be detected.

[0009]

According to the detection portion of the differential type magnetic sensor shown in FIGS. 6 and 7A, the core body is p-type, and the coil winding portion of the core is on the tip side. , It is difficult to insert an air-core coil wound in advance. Therefore, the winding is manually wound, and there is a problem that the winding is troublesome and the cost is increased.
In this regard, if a core body having the form shown in FIG. 7B is used, the coils wound around the core portions 43 and 44 can be air-core coils. However, the exciting coil 1 shown in FIG.
As shown in FIG. 7, a coil wound over the coils wound around the core portions 43 and 44 cannot be an air-core coil, and has the above-described disadvantages.

According to the detection section of the conventional differential type magnetic sensor, as is apparent from FIGS. 6 and 7, the exciting coil is located closer to the outside of the core body 1 as shown by an arrow in FIG. Then, the exciting magnetic flux passes between the two core portions 11 and 13 while bypassing the open end of the magnetic gap portion 24. If the amount of magnetic flux is large, it may affect the magnetic body of the object to be detected, such as a magnetic card conveyed in the vicinity of the magnetic gap 24, causing a problem such as demagnetization of recorded data. Can be If the amount of magnetic flux in the magnetic circuit is too large as described above, the rate of change of the amount of magnetic flux when the detection coil detects the object to be detected is small, and there is a problem that the sensitivity is deteriorated.

The present invention has been made to solve the above-mentioned problems of the prior art. By devising the shape of the core body, it is possible to simply insert a previously wound air-core coil into the core. It is an object of the present invention to provide a low-cost magnetic sensor that enables a coil to be mounted and has a simple manufacturing process. Another object of the present invention is to provide a magnetic sensor having high sensitivity, which can prevent the exciting magnetic flux from adversely affecting the magnetic body of the object to be detected.

[0012]

According to the first aspect of the present invention,
A magnetic sensor core body having two magnetic gaps in different directions, an exciting coil wound to generate a magnetic flux in the two magnetic gaps, and a change in magnetic flux generated by the exciting coil. And a detection coil wound to detect the magnetic field, and the two magnetic gaps are each composed of a pair of two cores, and one of the two cores constituting each of the two magnetic gaps is One of the excitation coil or the detection coil is wound around the coil as a coil winding portion, and a coil winding core portion is formed so as to protrude at a magnetic intermediate position with respect to the two magnetic gaps. A single coil for excitation or detection is attached to the section and the coil winding core section.

According to a second aspect of the present invention, a U-shaped core is formed by the two cores constituting the two magnetic gaps, respectively, and the coil winding core is provided in the middle of the U-shaped core. It is formed to protrude. According to a third aspect of the present invention, a coil is attached to the coil winding portion and the coil winding core portion at a portion extending linearly from the tip. According to a fourth aspect of the present invention, one of the two magnetic gaps is a detection gap facing the object to be detected. According to a fifth aspect of the present invention, there is provided a magnetic sensor core having a p-shaped cross section comprising a flat core portion and two L-shaped core portions projecting in opposite directions from one surface of the flat core portion. And two magnetic gaps are formed by the flat core portion and the two L-shaped core portions, and a coil winding core portion protrudes from the center of the other surface side of the flat core portion. is there. The invention according to claim 6 is characterized in that the magnetic sensor core is an H-shaped core, and between the two parallel cores of the H-shaped core and the two cores on the other side. Magnetic gaps are formed between the respective cores, and the coil winding core protrudes from the outside center of the plane of the H-shaped core body.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a magnetic sensor according to the present invention will be described with reference to the drawings. Note that the same components as those of the above-described conventional example are denoted by the same reference numerals. In FIG. 1 and FIG. 3A, the detection unit of the magnetic sensor includes two magnetic air gaps 24,
A magnetic sensor core body 1 having a magnetic field 25, an exciting coil 17 wound to generate a magnetic flux in the two magnetic gaps 24 and 25, and detecting a change in magnetic flux generated by the exciting coil 17. And two detection coils 15 and 16 that are wound in order to perform the operation. The magnetic sensor core 1 includes a flat core 10 and the flat core 1.
0, a core body having a p-shaped cross section is formed by two L-shaped core portions 13 and 14 projecting symmetrically in opposite directions from each other. Both ends 11, 1 of the flat core 10
2 and the two L-shaped core portions 13 and 14 form the two magnetic gap portions 24 and 25.

A U-shaped core is formed by the one L-shaped core 13 and one end 11 of the flat core 10, and an intermediate portion of the U-shaped core serves as the magnetic gap 24. I have. Another U-shaped core is formed by the other L-shaped core portion 14 and the other end portion 12 of the flat core portion 10, and an intermediate portion of the U-shaped core is formed by the magnetic gap portion 25. Has become. Between the two U-shaped cores on one side and the U-shaped core on the other side, a core part 1 for coil winding is provided.
8 are formed so as to protrude. This coil winding core 18
The two U-shaped cores are formed symmetrically with respect to the coil winding core 18 in a short columnar shape on the outer surface side of the flat core 10. An exciting coil 17 is wound around the coil winding core 18. Since the coil winding core portion 18 is formed in a straight line, an air-core coil wound in advance is used as the exciting coil 17, and this is used as the coil winding core portion 18.
It can be easily arranged simply by inserting it into the.

Further, each of the two L-shaped core portions 1
L-shaped core portions 13, 14 instead of the root portions of 3, 14
One of the two core portions 11, 13 and 12, 14 constituting the two magnetic gap portions 24, 25, respectively, is a coil winding portion. The two detection coils 15 and 16 are wound around these coil winding portions, respectively. Therefore, it is possible to easily arrange the two detection coils 15 and 16 simply by using air-core coils wound in advance and inserting them into the coil winding portions. Part of each detection coil 15, 16 is located in the magnetic gap 24, 25. The detection unit assembled in this manner is put into a case, and resin is poured into the case and fixed.

FIG. 5 shows a core body 1 constituting the detecting section.
And a case 28 in which the core body 1 is fixed by fixing the core body 1 by housing it and casting the resin. In FIG. 5, the case 28 has a gentle sliding arc on the sliding surface with the card 30 to be detected, and the gap 24 on the detection side of the core body 1 is located on the sliding surface side. The two core portions 11 and 13 forming the portion 24 and the tip surface of the wear-resistant member 18 are substantially the same as the sliding surface. Case 28
The above-mentioned sliding surface is polished so as to be one continuous surface with the end portions of the core portions 11 and 13 and the non-magnetic wear-resistant member 18 and to obtain good slidability. Is done. The detection principle of the magnetic sensor configured as described above has already been described, and the description is omitted here.

In the illustrated embodiment, the two core portions 11 and the two magnetic gap portions 24 and 25, respectively, are formed.
One of the coils 13 and 12 and 14 is used as a coil winding part, and the detection coil 1 is attached to these two coil winding parts.
5 and 16 respectively, and the two magnetic gaps 24,
The excitation coil 17 is attached to the coil winding core portion 18 which is formed at a magnetic intermediate position with respect to the magnetic gap 25, that is, a position where the same magnetic flux is generated in the magnetic gap portions 24 and 25. An exciting coil may be wound around each of the winding portions so as to cancel out the magnetic flux, and one detection coil may be attached to the coil winding core portion 18. With the latter configuration, when there is no object to be detected such as a magnetic card, the magnetic fluxes generated from the two excitation coils cancel each other out, and no output is obtained from the detection coils. When the object to be detected approaches one of the parts, the magnetic balance of the two magnetic gaps is disrupted, a signal is output from the detection coil, and the presence of the object to be detected can be detected. The magnitude of the magnetic permeability of the magnetic substance used for the detection target can be detected.

In the above-described embodiment, the two magnetic gaps 24 and 25 are formed by two cores 11 and
One of these two core portions 13 and 14 is a coil winding portion around which one of an exciting coil or a detection coil is wound, and the magnetic force applied to the two magnetic gap portions 24 and 25 is increased. The coil winding core portion 18 was formed to project at a typical intermediate position, and one coil was attached to each coil winding portion and the coil winding core portion. According to this embodiment, the following effects can be obtained. (1) One excitation coil and two detection coils, or two excitation coils and one detection coil can all be wound around a linear core, so that all of the coils are used. It was made up of an air-core coil, and it was possible to mount the coil simply by inserting it into a linear core.
Therefore, a low-cost magnetic sensor with a simple manufacturing process can be obtained. (2) The amount of magnetic flux in the magnetic gap on the detection side can be reduced, so that the magnetic recording portion of the object to be detected is demagnetized so that the recorded data is not destroyed. The rate of change of the amount of magnetic flux is increased, and the detection sensitivity can be increased.

Next, another embodiment shown in FIGS. 2 and 3B will be described. In this embodiment, the magnetic sensor core is an H-shaped core 31, and two cores 41 on one side of the H-shaped core 31 which are parallel to each other.
Magnetic voids 54 and 55 are formed between the two cores 43 and between the two cores 42 and 44 on the other side, respectively, and the coil winding core 48 protrudes from the center of the H-shaped core body 31 outside the plane portion. ing. The two cores 41, 43 and 42, 44 constituting the magnetic gaps 54, 55, respectively.
As a result, a U-shaped core is formed, and the coil winding core portion 48 is formed to project in the middle of the U-shaped core. The core part 43 and the core part 44 are coil winding parts, and the detection coils 15 and 16 are wound around the core part 43 and the core part 44, respectively, which are the coil winding parts. Core part 43
The core 44 extends linearly from the tip, so that it is only necessary to insert the air-core detection coils 15 and 16 wound in advance, and the arrangement of the detection coils 15 and 16 is extremely simple. . The exciting coil 17 is wound around the coil winding core portion 48. Since the coil winding core portion 48 also extends linearly from the tip, an air-core type exciting coil 17 wound in advance is used. The excitation coil 17 can be arranged very simply by inserting the coil 17.

The magnetic flux generated by the exciting coil 17 equally affects the two detecting coils 15 and 16. Assuming that one side of the two magnetic gaps 54 and 55, for example, the magnetic gap 54 is a detection gap facing the detection target, in a state where the detection target does not face the magnetic gap 54, The detection outputs of the two detection coils 15 and 16 are equal, and the differential output of both is zero. When the object to be detected faces the magnetic gap 54, the magnetic balance of the two magnetic gaps 54 and 55 is lost, and a differential output is obtained from the two detection coils 15 and 16. This operation is the same as that of the above-described embodiment, and the same effect can be obtained.

In the embodiment shown in FIGS. 2 and 3 (b), the exciting coils are respectively arranged on the core portions 43 and 44, which are the coil winding portions, so that the magnetic fluxes cancel each other. One detection coil may be arranged in the recycle core 48.

FIGS. 4A and 4B show still another embodiment. The embodiment shown in FIG.
With the p-type core body 1 in the embodiment shown in FIG. 1 as a main configuration, the coil winding core 38 is arranged on the opposite side to the embodiment shown in FIG. It is formed on the side surface, in other words, on the side on which the L-shaped core portions 13 and 14 are formed, so as to protrude from an intermediate portion between the L-shaped core portions 13 and 14. The exciting coil 17 is wound around the coil winding core 38. Core part 3 for coil winding
Since the coil 8 is formed in a short columnar shape and linearly protruded, the exciting coil 17 is formed in advance as an air-core type coil, and is inserted into the coil winding core 38 only at a predetermined position. Can be arranged. According to this embodiment, the same operation and effect as those of the embodiment shown in FIG. 1 can be obtained, and the outer surface of the flat core portion 10 becomes a flat surface. , For example, a core of a head for reading a recording signal of a magnetic card, MR
An element or the like can be mounted.

The embodiment shown in FIG. 4B is a form in which a flat core 50 is added to the embodiment shown in FIG. In the embodiment shown in FIG. 2, in a state where the coils 15 and 16 are wound around the coil winding core portions 43 and 44, some of the coils 15 and 16 project outward from the side surfaces of the core portions 43 and 44. I have. On the other hand, in the embodiment shown in FIG. 4B, the plate-shaped core 50 is integrally added outside the core portions 43 and 44 so as to be parallel to the core portions 43 and 44. The core 50 covers the outside of the coils 15 and 16. Therefore, there is an effect that the coils 15 and 16 are protected by the core 50.
Other members, for example, a core of a head for reading a recording signal of a magnetic card, an MR element, and the like can be mounted on the flat outer surface of the core 50.

[0025]

A magnetic sensor according to the present invention has a magnetic sensor core body having two magnetic gaps of different directions, and an exciting coil wound so as to generate a magnetic flux in the two magnetic gaps. A coil for detecting a change in magnetic flux generated by the exciting coil, and the two magnetic gaps each include a pair of two cores; One of the two cores constituting each of the two magnetic gaps is a coil winding part around which one of the exciting coil or the detection coil is wound, and is located at a magnetic intermediate position with respect to the two magnetic gaps. A coil winding core portion is formed so as to protrude, and one coil for excitation or detection is attached to each coil winding portion and the coil winding core portion. Therefore, according to the present invention, one excitation coil and two detection coils, or two excitation coils and one detection coil can be wound around a linear core, All of the coils were composed of air-core coils, and the coils could be mounted simply by inserting them into the linear core. Therefore, a low-cost magnetic sensor with a simple manufacturing process can be obtained.

Further, according to the present invention, the amount of magnetic flux in the magnetic gap on the detection side can be reduced, and the magnetic recording portion of the object to be detected is not demagnetized to destroy the recorded data. The rate of change in the amount of magnetic flux when the detection target is detected is increased, and the detection sensitivity can be increased.

[Brief description of the drawings]

FIG. 1 is a front sectional view showing an embodiment of a magnetic sensor according to the present invention.

FIG. 2 is a front sectional view showing another embodiment of the magnetic sensor according to the present invention.

FIG. 3 is a front view showing a core body of each of the above embodiments.

FIG. 4 is a sectional view showing still other various embodiments of the magnetic sensor according to the present invention.

FIG. 5 is a plan view conceptually showing a state in which the embodiment shown in FIG. 1 is incorporated in a case.

FIG. 6 is a sectional view showing an example of a conventional magnetic sensor.

FIG. 7 is a front view showing various examples of a core body used in a conventional magnetic sensor.

[Explanation of symbols]

 Reference Signs List 1 core body 10 flat core part 11 core part 12 core part 13 core part 14 core part 15 detection coil 16 detection coil 17 excitation coil 18 coil winding core part 24 magnetic gap part 25 magnetic gap part 31 core body 41 core part 42 core part 43 core part 44 core part 48 core part for coil winding 54 magnetic gap 55 magnetic gap

Claims (6)

[Claims] 1. A magnetic sensor core having two magnetic gaps having different directions, an exciting coil wound so as to generate a magnetic flux in the two magnetic gaps, and an exciting coil. A detection coil wound to detect a change in the generated magnetic flux, wherein the two magnetic gaps are each formed of a pair of two cores, and each of the two magnetic gaps is formed. One of the two core portions is a coil winding portion around which one of the excitation coil or the detection coil is wound, and a coil winding core portion is provided at a magnetic intermediate position with respect to the two magnetic gaps. A magnetic sensor which is formed so as to project and has one coil for excitation or detection attached to each of the coil winding portions and the coil winding core portion. 2. A U-shaped core is formed by two cores constituting each of the two magnetic gaps, and a coil winding core is formed so as to protrude in the middle of the U-shaped core. Item 7. The magnetic sensor according to Item 1. 3. The magnetic sensor according to claim 1, wherein a coil is attached to the coil winding portion and the coil winding core portion at a portion extending linearly from the tip. 4. The magnetic sensor according to claim 1, wherein one side of the two magnetic gaps is a detection gap facing the object to be detected. 5. A core body for a magnetic sensor having a p-shaped cross section including a flat core portion and two L-shaped core portions projecting in opposite directions from one surface of the flat core portion, 2. The coil winding core part according to claim 1, wherein two magnetic gaps are formed by the flat core part and the two L-shaped core parts, and a coil winding core part protrudes from the center of the other side of the flat core part. 3. Magnetic sensor. 6. The magnetic sensor core body is an H-shaped core body. The H-shaped core body is provided between two parallel cores on one side and between two cores on the other side which are parallel to each other. 2. The magnetic sensor according to claim 1, wherein a magnetic gap is formed, and a coil winding core protrudes from a center of an outer surface of the H-shaped core body.