JPH05210886A - Magneto-optical recording slip and reading method therefor - Google Patents

Abstract

PURPOSE:To prevent the annihilation of recording information by flaws, thin spot, etc., by providing recording parts recorded with information by application of magnetic fields in a thickness direction within the respective divided regions divided in parallel of a recording medium. CONSTITUTION:The recording part 2 is formed in the form of latent images on one surface of a box 1. The recording part 2 is constituted of a sheet-like recording part consisting of a three-layered structure consisting of a substrate 3, a recording film 4 and a protective film 5 and is stuck to the box 1. An alloy formed of a material contg. rare earth elements is used for the recording film 4. Magnetic domains are formed along the longitudinal direction of the recording part 2 and are so formed that the magnetization within the respective magnetic domains orients in the direction perpendicular to the film plane (thickness direction). The information is read by detecting the transverse intervals recorded in the recording part 2 from the rotating direction of the plane of polarization rotating according to the magnetization direction of the recording part at the time of reading such magneto-optical recording slip.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-optical recording sheet having a recording portion magnetized in a pattern having a width interval according to information, and a reading method thereof.

[0002]

2. Description of the Related Art Bar codes are known as means for recording various information. This bar code is printed on a label such as paper (hereinafter referred to as a bar code label) with a width of different thickness according to the information, such as a black (bar-shaped) code at wide and narrow intervals. The recorded information can be read by optically detecting the thickness of the bar and the bar interval.

[0003]

However, since the bar code is printed on the surface of paper or the like, there is a risk that part of the bar code will become thin or disappear due to scratches or scratches, and it may be discolored by ultraviolet rays or the like. . Moreover, this bar code occupies a large area because the recorded information density is relatively low. Further, such a bar code is unsuitable for use as a recording means for recording information or the like which is not desired to be known to others because a black bar or the like is visible to the naked eye. Therefore, in view of the above-mentioned conventional drawbacks, the present invention requires not only a small change over time but also a small occupied area, and the recorded portion is hidden and cannot be confirmed with the naked eye, so that highly secure information recording is performed. It is an object of the present invention to provide a magneto-optical recording sheet and a method of reading the same.

[0004]

That is, a magneto-optical recording sheet according to the present invention has a recording section in which information is recorded by applying a magnetic field in the thickness direction in each divided area of a recording medium which is divided in parallel. I have. Further, the method of reading a magneto-optical recording sheet according to the present invention reads information by detecting the width interval recorded in the recording section from the rotation direction of the polarization plane that rotates according to the magnetization direction of the recording section.

[0005]

The magneto-optical recording sheet of the present invention utilizes the magneto-optical effect, that is, the Kerr effect, the Faraday effect, and the like, and is made latent by detecting the rotating action of the polarization plane in the magnetized recording portion. It is possible to read the recorded information magneto-optically by detecting the pattern interval of the portion.

[0006]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a box 1 to which a magneto-optical recording sheet according to the present invention is attached, and a recording portion 2 is formed on one surface of the box 1 in a latent image state.
The recording unit 2 is composed of a sheet-like member having a three-layer structure of a substrate 3, a recording film 4, and a protective film 5. In this embodiment, an adhesive is applied to the box 1 formed of thick paper or the like. It is pasted with etc. The substrate 3 is made of glass, acrylic (PMM
A), polycarbonate, etc. are used. The recording film 4 is made of a material containing a rare earth element, and is made of an alloy such as terbium / iron / cobalt (Tb / Fe / Co) or gadolinium / terbium / iron (Gd / Tb / Fe). Magnetic domains are formed along the longitudinal direction of the portion 2, and the magnetization in each magnetic domain is oriented in the direction perpendicular to the film surface (thickness direction). The recording film forming material is not particularly limited to that of this embodiment.

Next, the recording principle of the magneto-optical recording sheet of this embodiment will be described. First, when the external magnetic field Ha is applied to the recording film 4 (magnetic material) of the recording unit 2 in the thickness direction as shown in FIG. 3, the magnetization Ms is magnetized in the opposite direction. next,
When a part of the magnetized region is heated to the Curie point or higher by the laser beam or the like condensed through the condenser lens 6, the magnetization disappears in the region (see FIG. 4). Therefore, in the magnetization disappearance region, the magnetization Ms in the adjacent magnetic domain is
Inversion magnetization Ms is generated due to the influence of (see FIG. 5).
Although information is recorded by this, the width of the reversal magnetization Ms can be appropriately adjusted by a condenser lens or the like.

Next, a method of reading (reproducing) the magneto-optical recording sheet according to this embodiment will be described. For example, in FIG. 6, beam-shaped laser light emitted from a semiconductor laser (LD) is irradiated at a constant speed along the longitudinal direction (α) of the recording unit 2. Then, the laser light emitted by this scanning is changed from circularly polarized light to linearly polarized light by the polarizer 7 provided on the forward light path on the way, but when reflected by the area A on the recording film 4, the Kerr effect is obtained. Therefore, the plane of polarization rotates by any angle ± φ _k depending on the magnetization direction. Therefore, if the analyzer 8 is arranged on the return path so as to transmit the laser light after the reflection whose polarization plane is rotated by a predetermined angle (for example, + φ _k ), it is converted into a light amount change. . Therefore, by converting this into an electric signal by the light receiving element 9 such as a light emitting diode, the information recorded in the recording unit 2, that is, the width D of the area A magnetized in a specific direction and the adjacent area magnetized in the same direction. The distance to the area can be detected. In addition,
The Kerr effect is used in the reading of the magneto-optical recording sheet of this example. For example, for laser light traveling into the recording film,
The rotation phenomenon of the polarization plane may be generated twice by the Faraday effect.

[0009]

As described above, according to the magneto-optical recording sheet of the present invention, it is possible to record information by making it magneto-optically latent in the recording portion. There is no possibility of being discriminated, and it is possible to prevent the recorded information from being lost due to scratches or scratches. Further, according to the present invention, since the recorded information can be recorded in the thickness direction, the recording density can be greatly improved, and the size can be reduced accordingly. Further, according to the method of reading a magneto-optical recording sheet according to the present invention, by utilizing the magneto-optical effect, that is, the Kerr effect, the Faraday effect, etc., and detecting the rotating action of the polarization plane by the magnetized recording unit, Since the pattern of the converted recording portion can be identified and the recorded information can be read by this, it is possible to read the information even if there are scratches or scratches on the surface.

[Brief description of drawings]

FIG. 1 is a perspective view showing a box to which a magneto-optical recording sheet according to the present invention is attached.

FIG. 2 is a sectional view taken along the line I-I in FIG.

FIG. 3 is an explanatory diagram showing a recording method of a magneto-optical recording sheet according to the present invention.

FIG. 4 is an explanatory diagram showing a recording method of a magneto-optical recording sheet according to the present invention.

FIG. 5 is an explanatory diagram showing a recording method of a magneto-optical recording sheet according to the present invention.

FIG. 6 is an explanatory view showing a method of reading a magneto-optical recording sheet according to the present invention.

[Explanation of symbols]

 2 recording section

Continuation of front page (72) Shinichi Kato 1-10-12 Ueno, Taito-ku, Tokyo Nidec Electric Seiki Co., Ltd.

Claims (2)

[Claims] 1. A magneto-optical recording form, comprising a recording section in which information is recorded by applying a magnetic field in the thickness direction in each of the divided areas of the recording medium which are divided in parallel. 2. A method of reading a magneto-optical recording form, characterized in that the information is read by detecting the width interval recorded in the recording section from the rotation direction of the polarization plane that rotates according to the magnetization direction of the recording section.