JPH04204070A - Magnetic sensor for detecting stamp - Google Patents

Abstract

PURPOSE:To surely and accurately detect the stamp pattern of a bomb by arranging a ferromagnetic magnetoresistance element to the end surface of the magnetic pole of a permanent magnet and detecting the difference of flux density appearing corresponding to the presence of a stamp. CONSTITUTION:A scanning type probe is constituted of a contact main body 15 having a parallelepiped shape, the MR element 2 attached to the front thereof and the permanent/magnet 1 attached to the rear thereof and slot-like horizontal axial holes 16 are formed at the upper part of the main body 15. The MR element 2 are received in the cavity 17 of the main body 15 to eliminate the trouble at the time of scanning. The scanning type probe is supported by inserting a support shaft 18 through the horizontal axial holes 16 and can be freely moved in the direction shown by an arrow. The change of magnetic flux generated when the probe is allowed to approach a stamp part is guided to the electric circuit of a character discriminating treatment circuit and the predetermined discrimination of a stamp is carried out.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to stamps, uneven characters and symbols engraved on the surface of a ferromagnetic material such as a high-pressure gas container, or hidden characters not exposed on the surface. This is a proposal for a magnetic sensor that electromagnetically reads embedded characters, etc., and in particular, a magnetic sensor that is characterized by the structure of a scanning contact disposed at the end of the sensor.

[Conventional technology]

Generally, high-pressure gases such as oxygen, nitrogen, acetylene, and carbon dioxide are dangerous substances, and their handling is regulated by the High Pressure Gas Control Law. Therefore, the containers that contain these gases are also strictly regulated, and it is required that the type of gas contained and the method of management be stamped on the surface of the container with various letters, symbols, and numbers.

In addition, these high-pressure gas containers, called cylinders, are managed by marking them with unique letters, symbols, and numbers.

These characters, symbols, and numbers are most commonly read with the human eye, and misreading due to errors or the like poses a major problem.

In order to solve such problems, conventionally,
Optical pattern reading devices such as those proposed in Japanese Patent Laid-Open No. 7553, Japanese Patent Application Laid-Open No. 59-208678, have been proposed. This conventional technique was developed to increase the reliability of the reading results by optically reading stamped characters and recording the results, thereby eliminating human intervention as much as possible.

[Problems to be solved by the invention] However, in these optical pattern reading devices,
The engraved characters, symbols, and numbers on gas cylinders, which are the subject of this invention, are often damaged during use, especially during transportation, rusted, or even covered with other substances. Therefore, there was a problem that optically accurate reading was impossible.

What is more important is that in the case of gas cylinders, the surface is not only curved but also uneven due to dust adhesion and rust formation, so it is especially important to scan the sensor contacts properly. There are many cases where this cannot be done, and as a result, there is a problem in that detection errors occur and accurate character recognition is hindered.

The present invention has been made in view of the problems faced by conventional sensors, and its purpose is to reliably and accurately mark patterns engraved on the surface of hard materials such as metals. The object of the present invention is to propose a structure for a magnetic sensor, particularly a scanning contact, which can accurately detect and record information.

[Means for solving the problem] In order to overcome the above-mentioned problems, firstly, a magnetic sensor is used in place of the optical pattern reader, and secondly, the structure of the contact for reading is improved. discovered that it is effective to provide a movable support so that it can be moved freely depending on the surface of the marking, and developed a magnetic sensor with the following basic structure. That is, the present invention uses a contact mainly consisting of a permanent magnet and a ferromagnetic magnetoresistance element disposed on one pole end face of the permanent magnet.
゛A magnetic sensor that identifies the engraved characters by applying magnetic force to the character part engraved on a ferromagnetic material and detecting the difference in magnetic flux density that appears depending on the presence or absence of the engraved character, and this magnetic sensor detection end A support shaft is horizontally suspended in the casing of the unit, and a contact body comprising a ferromagnetic magnetoresistive element on the front side and a permanent magnet on the rear side is attached to the support shaft, and the installation is in a state is supported so that it can freely move and swing back and forth so that the sensor surface of this contact is always perpendicular to the engraved surface through a horizontal shaft hole with a long bow-shaped cross section provided at the top of the contact. A magnetic sensor for detecting markings, further comprising an elastic belt rotatably and loosely fitted onto the surface of the scanning contactor main body of each upper case. , we propose.

[Function] Below, the function of the magnetic sensor for marking detection of the present invention will be explained in the third section.
This will be explained based on FIGS.

FIG. 3 schematically shows the sensor section located on the detection end side of the magnetic sensor of the present invention, and this sensor section is a permanent magnet having an S pole and an N pole magnetized in one direction. 1 and a ferromagnetic magnetoresistive element (hereinafter simply referred to as rMR element) 2 arranged on one magnetic pole (S) surface 1a, that is, on the front surface.

Therefore, the situation (flow of IF flux) when a magnetic sensor 1 as shown in FIG. 3 is placed close to a ferromagnetic material 5, such as a high-pressure gas container, to read markings is shown in FIGS. 4 and 5.
This will be explained according to the diagram.

First, FIG. 4 shows a state in which the magnetic sensor 1 is brought close to the non-engraved portion 5 of a ferromagnetic material. In this state, the magnetic flux flowing from the magnetic pole surface 1a of the permanent magnet to the non-engraved portion 3 passes through all parts of the MR element 2 equally.

Next, when the magnetic sensor is brought close to the stamped part 5 of the ferromagnetic material, as shown in FIG.
are both ends 6.7 of the non-engraved part 3 and the engraved part 5 of the ferromagnetic material.
However, magnetic poles by permanent magnets are induced at both ends 6.7, and the polarity of the magnetic flux is the same.

Therefore, the magnetic fluxes repel each other and each head in a direction far from the marking portion 5, so that the amount of magnetic flux passing through the MR element 2 decreases. The reason for this is that the deepest part of the groove of the marking part 5 becomes the magnetic pole opposite to the magnetic pole of the adjacent magnetic pole surface of the permanent magnet, and the magnetic poles at both ends 6.7 of the surface part of the ferromagnetic material become the same polarity. It is.

The magnetic sensor of the present invention is designed to identify a stamp as nothing by guiding the above-described change in magnetic flux to the electric path of the electric circuit shown in FIG. 6 of the character recognition processing section. That is, in FIG. 6, 8 is the MR element 2.
The resistor 9.10 is a load resistor for converting the change in resistance value due to the magnetic field into a change in voltage, and the resistor 9.10 is a load resistor that causes the output P1 of the differential amplifier 11 to take a value of O when the magnetic sensor approaches the non-engraved part 3. This is a bias resistor for adjusting. Therefore, when the magnetic sensor is close to the non-engraved portion 3, the output of P1 is naturally O.

When the magnetic sensor approaches the marking part 5, the M'
The resistance value of the R element 2 decreases because the magnetic flux passing over the MR element 2 decreases, and the output of Pl of the differential amplifier 11 increases. 20 By shaping the increase in the output of P1 by the waveform shaping circuit 12, a detection signal corresponding to the presence or absence of a marking is obtained.

In contrast to the configuration of such a character recognition processing section, in the present invention,
In order to accurately detect the distinction between the non-engraved part 3 and the marked part 50,
The contact of the sensor part is movably supported so that it can swing freely in the front-rear direction, left-right direction, and up-and-down direction according to the marking surface, thereby making it possible to center the sensor against the marking surface. We have ensured that the accuracy of sensing has improved.

That is, since the engraved surface is a ferromagnetic material, and since the above-mentioned contactor of the present invention was originally constructed mainly of the permanent magnet 1, it is only necessary to bring the detection part (sensor part) of the magnetic sensor close to the engraved surface. Then, the contactor itself becomes magnetically attached due to the action of the magnetic attraction force.

Therefore, in the case of the magnetic sensor of the present invention, since the contact automatically comes into close contact with the stamped part of the gas pump, etc., all that is required is to slide the sensor along the stamped part.

Furthermore, when the engraved surface of the contactor slides, an annular, preferably rubber belt is loosely fitted to the surface of the contactor to make the movement smoother, so that the contactor can move more smoothly. It is effective to do so.

〔Example〕

Next, regarding the magnetic sensor of the present invention, the structure of the scanning contact of the sensor section will be explained based on FIGS. 1 and 2.

FIG. 1 is a cutaway perspective view of the sensor section (detection section) of the magnetic sensor of the present invention, and a scanning contactor is disposed in the detection section at the tip of the casing of the sensor so as to be movable mainly in the front-rear direction. It is.

This scanning type contactor is mainly composed of a rectangular parallelepiped contactor body 15, an MR element 2 attached to the front side of this body, and a permanent magnet 1 attached to the back side. A horizontal hole 16 having an elongated cross-sectional shape is formed along the length. Note that the MR element 2 is
Since this contact body 15 becomes an obstacle when scanning along the marking portion, a recess 17 is provided in this body 15 and the contact body 15 is accommodated therein.

The scanning contactor can be supported in the direction of the arrow shown in the figure (back and forth direction...long hole direction) by inserting a support shaft 18 which is placed horizontally on the detection part of the sensor casing into the horizontal shaft hole 16 of the scanning contactor. It can be moved freely,
Separately from the magnetic sensor body, only this scanning contactor can be moved in the front-back direction.

Further, in the magnetic sensor of the present invention, an elastic belt, preferably a rubber belt, is loosely fitted around the scanning contactor. By adding such a configuration, when the scanning contactor is scanned along the marking surface, its movement is facilitated (by the rubber belt sliding and rotating around the contactor body). At the same time, since it acts as a buffer material, it is possible to obtain something that effectively protects the contact.

〔Effect of the invention〕

As explained above, according to the magnetic sensor of the present invention, together with the adoption of a movable scanning contactor, even if the detected object (
Even if the surface of the high-pressure gas cylinder stamp (letters) is corroded or dirty, it is possible to reliably detect the stamp without being affected by surrounding magnetic leakage or electrical noise.

Moreover, the magnetic sensor of the present invention has a simple structure and is inexpensive, and above all, the scanning type contactor is front and rear.

In addition to being able to move freely left and right and up and down, it also magnetically attaches to the engraving surface, ensuring centering of the engraving, and there is no detection blur, and together with the use of a rubber belt, accurate sensing is possible.

[Brief explanation of the drawing]

FIG. 1 is a cutaway perspective view of the sensor section of the magnetic sensor of the present invention, FIG. 2 is a sectional view of a scanning contact with a rubber belt, and FIG. 3 is a conceptual diagram of the scanning contact of the present invention. Figure 4 shows
FIG. 5 shows a state in which the scanning contact of the magnetic sensor is close to the non-engraved part, FIG. 5 is a sectional view of the scanning contact of the magnetic sensor close to the stamped part, and FIG. It is an electronic circuit diagram of a magnetic sensor. 1... Permanent magnet, 2... Ferromagnetic magnetoresistive element (MR element), 15...
Contact body, 16...horizontal hole, 17...dent,
18...Support shaft patent applicant: Japan Heavy and Chemical Industry Co., Ltd. Yoshikazu Kakinoki Patent attorney: Jun Ogawa Patent attorney: Morio Nakamura Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] 1. Using a contact mainly consisting of a permanent magnet and a ferromagnetic magnetoresistance element disposed on one pole end face of the permanent magnet, a magnetic force is applied to a character part engraved on a ferromagnetic material. This is a magnetic sensor that identifies the stamped characters by applying a A magnetic sensor for detecting markings that has a contact main body, which is equipped with a ferromagnetic magnetic resistance element on the front side and a permanent magnet attached on the rear side, attached to the support shaft. 2. Magnetic force is applied to the character part engraved on the ferromagnetic material using a contactor mainly consisting of a permanent magnet and a ferromagnetic magnetoresistance element arranged on one pole end face of the permanent magnet, and the engraved part is engraved. This is a magnetic sensor that identifies the engraved characters by detecting the difference in magnetic flux density that appears depending on the presence or absence of the characters. A contact body comprising a ferromagnetic magnetic resistance element and a permanent magnet attached to the rear surface thereof is attached, and an elastic belt is rotatably fitted loosely onto the surface of the contact body. Magnetic sensor for detecting markings. 3. Magnetic force is applied to the character part engraved on the ferromagnetic material using a contactor mainly consisting of a permanent magnet and a ferromagnetic magnetoresistance element arranged on one pole end face of the permanent magnet, and the engraved part is engraved. This is a magnetic sensor that identifies the engraved characters by detecting the difference in magnetic flux density that appears depending on the presence or absence of the characters. The contact body is equipped with a ferromagnetic magnetoresistive element and a permanent magnet is attached to the rear side of the contact body. A magnetic sensor for detecting markings, characterized in that the sensor surface is supported so as to be freely movable and swingable in the front-rear direction so that the sensor surface is always perpendicular to the marking surface. 4. Magnetic force is applied to the character part engraved on the ferromagnetic material using a contactor mainly consisting of a permanent magnet and a ferromagnetic magnetoresistance element arranged on one pole magnetic end face of the permanent magnet, and the engraved part is engraved. This is a magnetic sensor that identifies the engraved characters by detecting the difference in magnetic flux density that appears depending on the presence or absence of the characters. The main body of the scanning contact is equipped with a ferromagnetic magnetoresistive element and a permanent magnet is attached to the rear side, and the sensor surface of this contact is engraved through a horizontal hole with an elongated cross section provided at the top of the main body of the scanning contact. The main body of the contact is supported so that it can move and swing freely in the front and rear directions so as to be always perpendicular to the surface, and an elastic belt is loosely fitted on the surface of the contact body so that it can rotate. Magnetic sensor for detecting markings.