JPS5996543A - Recording medium for optical memory - Google Patents

Abstract

PURPOSE:To form a simple track guide, to improve the yield of production and to reduce the production cost by forming a thin film layer absorbing laser light in the form of stripes in accordance with the shape of recording tracks to form the guide for an optical head. CONSTITUTION:In the recording medium, a part between stripes absorbing laser light is used as a recording track. If data are written in a recording layer 3 on the back side of a transparent part 6 between two laser absorbing parts 5, the intensity distribution of reflected light shifts the peak point right as shown in the figure when a laser spot is shifted left (d). When the spot is shifted right (f), the peak is shifted left, and at the correct tracking state (e), normal distribution symmetric about the axis is formed. Therefore, the polarization of the optical intensity is detected by bisected photosensors and the servo of the optical head is executed to maintain correct tracking. The guide of the track is formed by a material colored by light and the colored part may be left at the inside of a thin film having a proper film thickness. Said method can be performed by the same process as that of groove formation using a resin curable by ultraviolet rays.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to guiding an optical head provided in advance on an optical memory recording medium.

Conventionally, a groove provided on the surface of an optical disk has been known as this type of guide. FIG. 1 shows the shelf 1 schematically. 1 is an acrylic or glass disk substrate, and the groove 2 is made of ultraviolet curing acrylic resin (PMMA).
).

That is, only the portion to be left as a recording track is cured by applying ultraviolet rays, and the other portion is removed. The recording material 3 is further laminated on such an uneven surface by vapor deposition, sputtering, or the like. Further, in order to increase the stability of the material, a protective film may be further provided thereon. Recording is performed on the image portion of the groove, and tracking is performed by the following method.

Figure 2 shows the situation when the laser beam is focused on the disk surface.As shown in the figure, when correct tracking is performed (b), and when the spot shifts to the left ( a), and if the spot shifts to the right (1)
The intensity distribution of each reflected light is shown. That is, the graph shows the light intensity on the vertical axis and the distance on the horizontal axis. When tracking is performed correctly, the reflected light has a normal distribution symmetrical about the center of the track. Furthermore, if the spot shifts to the left from the track, the peak point of the light intensity shifts to the left, and conversely, if the spot shifts to the right, the peak also shifts to the right. Therefore, correct tracking can be achieved by returning the reflected light onto the photosensor, detecting the balance of the previous light intensity with the two photosensors A and B as shown in the figure, and servoing the optical head based on this signal. The disadvantage of this method is that the groove depth must be controlled to λ/8 in order to improve the tracking effect. That is, in the process of creating the groove, PM
Careful attention must be paid to controlling the MA film thickness.

The present invention provides a new method in place of such tracking using grooves, and is intended to reduce the burden on manufacturing.

FIG. 3 shows an example of an optical memory recording medium according to the present invention. 1 is a disk substrate made of glass or
It is acrylic resin. Reference numeral 4 denotes a guide layer of the track according to the present invention, and the guide consists of laser light absorbing portions left in the form of stripes 5. 6 is a transparent body left between the stripes.

3 is an optical memory recording material, on which a protective coating 7 is applied.

The principle of tracking according to the present invention is shown in FIG. The present invention also utilizes the slope of the intensity distribution of reflected light as in the prior art, but the situation is opposite to the previous case. That is, if we consider the case of writing on the recording layer 3 located behind the transparent part A sandwiched between the two laser absorption parts 5, when the laser spot shifts to the left (d), the intensity distribution of the reflected light will be As shown in the figure, the beater point is on the right. Moreover, when the spot shifts to the right (1), the peak shifts to the left, and in the correct tracking state (1), an axially symmetrical normal distribution is obtained. Therefore, correct tracking can be maintained by detecting the slope of the light intensity using a two-part photo sensor as in the conventional 31 method, and performing servo on the light.

FIG. 5 shows another embodiment of the present invention, in which the laser light absorbing portion 5 is utilized for the recording track. Therefore, the recording material 6 must be provided on the laser light source side, and the recording layer and the tracking layer are stacked in the opposite direction to that in FIG. 4. The intensity distribution of the reflected light is shown in Figure 5 (g) and (h).
+h). The control method using the two-split photosensor is also the same here.

Now that the embodiment of the present invention has been clarified, the method for creating the lullimeter will be briefly described next.

In the present invention, since a light absorption layer is used to guide the optical head,
Anything that can provide contrast between the transparent part and the colored part (including infrared) has potential. Silver halide, organic dye thin film, organometallic compound, film 1
．． Otokuromisoku wood.

Examples include To compounds.

In detail, when silver halide is used with reference to FIG. 3, silver halide contained in a binder is first coated on a multi-disk substrate to a thickness of several μm. After that, the track is written using a focused laser beam.

Therefore, this laser light m has a highly accurate mechanism for eccentricity of the disk and for feeding the laser beam. Another practical method for writing tracks is to use a mask having a track shape, bring it into close contact with the j-isk, and expose the entire surface at once. After exposure, the disk is developed to cause silver to precipitate within the coating layer and turn black. Thereafter, a Te-based compound serving as an optical recording material or a magneto-optical material may be laminated and a protective coating may be applied.

Therefore, the method using silver halide is an application of conventional photographic technology.

7. The above method also applies when using otochromic compounds, metal compounds, or organic dyes. ff1J, it is sufficient to color only the guide portion of the track by using photooxidation/reduction or photodecomposition.

When using a Te-based compound, 'Te and T e
It may be possible to co-deposit O2 and cause a thermal change using laser light to turn it black.

As described above, in the present invention, the track guide is formed using an ion material that changes color depending on light, and there is no need to control the depth of the groove, which was required in the past. The colored portion may be left in a thin film having an appropriate thickness, and this method can be carried out in the same process as forming grooves using an ultraviolet curing resin.

Further, in the present invention, the optimum effect can be obtained by selecting the light absorption characteristics according to the wavelength of the laser head used. Furthermore, if a light reflecting material is used in the protective coating layer, the reflection efficiency will increase and the trunking S/N will increase.

As described above, according to the present invention, a simple track guide can be made, which is effective in improving manufacturing yield and reducing costs.

[Brief explanation of the drawing]

FIG. 1 shows the configuration of a conventional track guide, and FIG. 2 shows its tracking principle. FIG. 6 shows a track guide according to the present invention, and FIGS. 4 and 5 show its tracking principle. Number 1 in the figure...Disk substrate 2...Guide groove 3...Recording layer 4...Tracking thin film layer 5...Laser light absorption section 6...Transparent part 7...Protective coating and beyond -1- Cα ) (b') (c) Figure 2 X-I'! , Figure 4 (1) No. Ck) < i > 1

Claims (3)

[Claims] (1) An optical memory recording medium characterized in that a thin film layer that absorbs laser light is provided within the plane of the optical memory recording medium, and this layer is formed into stripes to match the shape of the recording track to serve as a guide for the optical head. . (2) A special N'r #i! feature in which the line portion that absorbs laser light is used as a recording trunk. 1. The optical memory recording medium according to item 1. (3) Optical memory recording medium 0 characterized in that recording tracks are formed between stripes that absorb laser light.