JPH01209587A - Information recording/reading method - Google Patents

Abstract

PURPOSE:To highly sensitively read information even when detecting elements cannot be stuck by changing the magnetic characteristics of a part of the base material of ferromagnetic material, writing the information, impressing and magnetizing a magnetic field in parallel to a surface, detecting a leakage flux, and attaining reading. CONSTITUTION:When laser beams 2 are irradiated on a base material 1 of a cold rolled steel sheet, a sharp heating cooling operation is applied to an irradiated part 3, an extreme residual stress is generated, the magnetic characteristics of the part 1 are changed from those of the circumferential area, and holding force becomes larger than that of the circumferential area. When the magnetic field is impressed and magnetized over the whole writing area in parallel with the base material surface, large residual magnetization is generated in the part where the laser beams are irradiated. By using hole elements arranged vertically to the base material surface so as to detect the leakage magnetic flux in parallel with the base material surface due to the residual magnetization, the recorded information can be highly sensitively read. Thus, by writing the necessary information by means of a symbolized bit pattern, it can be utilized as the information recording system of a marker, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a novel information recording and reading method that can be preferably used, for example, in automatic factory production lines.

[Conventional technology]

FIG. 5 is a first example of a conventional information reading method, and is a block diagram of a magnetic information reading device disclosed in Japanese Utility Model Application Publication No. 58-10151. In the figure, (7) is a magnetic herad core. , (8) is a winding, and (9) is a steel plate member.

FIG. 6 shows a second example of the conventional reading method, and is a block diagram of a conventional magnetic information reading device disclosed in Japanese Patent Application Laid-Open No. 57-200975. In the figure, (9) is a steel plate member, and αG is a Hall element disposed on a surface corresponding to the steel plate member which is a medium.

[Problem to be solved by the invention]

A conventional reading device is configured, for example, as in the first example above, and magnetic information is written directly onto the surface of a steel plate member using a magnetic head. In this writing method, there is no magnetic difference between the writing bit part and the steel plate base material, and the flow of magnetic flux during writing is also perpendicular to the surface of the steel plate member, so the residual magnetic flux of the written information bit is extremely large. The disadvantage was that it was low.

In addition, in the second example, the magnetic information written on the surface of the copper plate member was read by a Hall element arranged on the surface corresponding to the steel plate member, but the Hall element essentially uses a magnetic flux that is perpendicular to the element surface. In order to detect the The disadvantage was that the amount of magnetic flux transmitted was very small, resulting in low detection sensitivity.

This invention was made to solve the above-mentioned problems. For example, when a coating film is attached to a copper plate member after a process such as painting, or when the information bit and the reading head cannot come into close contact due to the structure. However, the purpose is to provide an information recording method with high reading accuracy.

[Means to solve the problem]

The information recording/reading method according to the present invention writes information on a part of a base material made of a ferromagnetic material by changing the magnetic properties at predetermined intervals, and writes information parallel to the surface of the base material. A magnetic field is applied over the entire area of the base material to magnetize it, and leakage magnetic flux parallel to the surface of the base material is detected to record and read information.

[Function] The information bit part in this invention has magnetic properties different from those of the steel plate base material, and is magnetized parallel to the surface of the steel plate member, so that leakage magnetic flux that is half parallel to the surface of the steel plate member is transmitted perpendicularly to the steel plate member. The information is read with high precision by the Hall element placed in the sensor.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view illustrating a method for manufacturing a magnetic marker for automobiles according to an information recording/reading method according to an embodiment of the present invention. In the figure, (1) is.

The base material is a thin plate for automobiles, and is a part that is being processed using a ferromagnetic material such as a cold-rolled steel plate (for example, JIS 5PCC). (2) is a high energy density heat source such as a laser beam or an electron beam; (3) is an information bit formed by irradiation with a high energy density heat source;
They are formed on the base material (1) at predetermined intervals.

FIG. 2 is a side configuration diagram showing how the magnetic marker for automobiles obtained as shown in FIG. 1 is magnetized. The core of the electromagnet for magnetization, (5) is a winding.

Figure ia is a perspective view showing how the leakage magnetic flux from the information bit magnetized by the method shown in Figure 2 is detected. In Figure 1, (6) detects the magnetic flux parallel to the surface of the base material. It is a Hall element-like sensor placed perpendicular to the surface of the base material.

FIG. 4 is a relationship diagram showing the relationship between the amount of magnetism detected by the method of FIG. 3 and position, with the horizontal axis representing the position and the vertical axis representing the amount of leakage magnetic flux. In FIG. 1, when a laser beam of, for example, about 10 W/ci is irradiated onto a base material (1) of a plate-shaped cold-rolled steel plate, the portion irradiated with the laser beam is rapidly heated. Then, when the laser beam irradiation is stopped, the part that has been irradiated with the laser beam is now rapidly cooled. Therefore, the part irradiated with the laser beam is subjected to a rapid heating and cooling action, producing extreme residual stress, and the magnetic properties of the part irradiated with the laser beam change from those of the surrounding area, resulting in a coercive force greater than that of the surrounding area. When such a base material is magnetized by applying a magnetic field over the entire writing region parallel to the surface of the base material shown in FIG. 2, a large residual magnetization is generated in the portion irradiated with the laser beam. In this case, the magnetization conditions were 24000 A/m.
If it is 800 A/m or more, the steel plate will be saturated and it can be carried out.

Moreover, since the purpose of laser beam irradiation is only for heating effect, no unevenness is produced on the surface of the base material (1).

Therefore, the residual magnetization of the part irradiated with the laser beam is large, and the residual magnetization of the part not irradiated with the laser beam is small, so the part irradiated with the laser beam can be used as an information bit, and the presence or absence of irradiation with the laser beam can be arbitrarily determined. Any information can be recorded by selecting . The recorded information is recorded, for example, by using a Hall element or the like arranged perpendicularly to the substrate surface to detect leakage magnetic flux parallel to the substrate surface due to residual magnetization, as shown in FIG. 4. The relationship between the position and the amount of leakage magnetic flux as shown in can be detected, making it possible to read information with high sensitivity. If necessary information is written in a encoded bit pattern in this way, it can be used as an information recording method such as a marker.

Since it uses magnetism to enable highly sensitive detection, information can be transmitted even after the surface of the base material (1) has been painted, or when the base material (1) and the detection element cannot be brought into close contact due to structural reasons. Can be read. Note that the information to be recorded is of course arbitrary, and can include, for example, the coded name of the article, the color of the paint to be applied in the primary process, the size, shape, lot number, date of manufacture, etc. .

In this example, the information was written as a combination of bits, but by selecting the beam width of the laser beam to a desired value, it can be changed arbitrarily, for example, from several tens of micrometers to several tens of micrometers. It is also possible to make the beam irradiated into a bar shape and use the same code system as existing bar codes.

Furthermore, in this example, cold rolled steel plate (5PCC) was described as the base material (1) and the ferromagnetic material.
It may also be a ferromagnetic material made of an alloy of other iron-based copper, zinc, chromium, nickel, manganese, aluminum, or the like. Alternatively, a ferromagnetic ceramic may be used.

Incidentally, in the above embodiments, the case where a steel plate for automobiles is used as the base material has been described, but it is needless to say that the present invention is not limited to this.

〔Effect of the invention〕

As described above, according to the present invention, information is written on a part of a base material made of ferromagnetic material by changing the magnetic properties at predetermined intervals.
A magnetic field is applied across the entire writing area parallel to the surface of the base material to magnetize it, and reading is performed by detecting leakage magnetic flux parallel to the surface of the base material, so it can be read easily after painting or other processes. Even in cases where the base material and the detection element cannot be brought into close contact due to the structure, information can be read with high sensitivity and the reading accuracy is high.

Further, since magnetization is performed by applying a magnetic field over the entire writing area parallel to the surface of the base material at once using one magnetizing electromagnet, the structure of the magnetizing device is simplified.

[Brief explanation of the drawing]

FIG. 1 is a perspective view illustrating a method for manufacturing a magnetic marker for automobiles according to an information recording/reading method according to an embodiment of the present invention, and FIG. 2 is a perspective view of a magnetic marker for automobiles according to an embodiment of the present invention. FIG. 3 is a perspective view showing how leakage magnetic flux is detected from an automobile magnetic marker according to an embodiment of the present invention; FIG. 184 is a diagram showing an embodiment of the present invention. A diagram showing the relationship between the amount of leakage magnetic flux detected by the information recording reading method according to the example and the position, and FIGS. 5 and 6 are configuration diagrams showing the magnetic information reading device according to the conventional information recording reading method, respectively. be. (1)...Base material, (2)...Laser beam, (3)
...Information bit. (6)...Hall element. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] A process of changing the magnetic properties of a part of a base material made of a ferromagnetic material at predetermined intervals and writing information thereon. A magnetic field is applied across the entire writing area parallel to the surface of the base material to magnetize it. and a step of detecting and reading leakage magnetic flux parallel to the surface of the base material.