JPS5938943A - Optical information storing medium - Google Patents

Abstract

PURPOSE:To distinguish easily a signal information pit from another information pit in which other information is recorded, by forming the signal information pit with a higher reflectance than that given from a tracking guide. CONSTITUTION:A metallic thin film of Te, Se, etc. is used to a record layer 5 of a substrate made of a synthetic resin, etc. A tracking guide 6 and a signal information pit 7 are formed spirally or concentrically on the layer 5. The pit 7 has a higher reflectance than the light given from the guide 6 when the information is read by an optical head. The depth (a) of the guide 6 is set at lambda/8; while the depth (b) of the pit 7 is set at lambda/16, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an optical information storage medium capable of storing or reading information using focused laser light.

[Technical background of the invention and its problems]

As an information storage medium, a compact disc (CD) used for a digital audio disc (DAD) is used.
Read-only information storage media, such as disk-shaped or tape-shaped optical video discs, which can read information using focused laser light, image files, and computer output memory (COM).
) Information storage media for recording and playback that have a disk or tape shape and allow information to be written to and read from the recording layer using focused laser light. and erasable information storage media.

Such information storage media have narrow track pitches in order to increase the density of information. Therefore, in order to make the optical head follow a predetermined track 4 during reading or writing, a tracking guide consisting of a groove or a convex portion having a step with respect to a flat surface is formed in advance on this type of information storage medium. There is. Furthermore, if specific signal information such as the track number or sector position indicating the position where information is recorded is recorded in advance, the software by the recording/reproducing device will be easier. It is also equipped with signal information bits consisting of grooves and convex portions with steps (also referred to as a tracking guide with f IJ formatting).

The tracking guide and the signal information bit are formed by unevenness on a flat surface, and the difference in the amount of light reflected therefrom can be read as information. By the way, the difference in the amount of reflected light from the unevenness (modulation degree as a signal) becomes maximum when the level difference between the surface unevenness is λ/4 (
λ is the wavelength of the 111 light for reading. same as below. ), and track deviation detection based on the diffraction pattern of light reflected from the unevenness (this type of detection is also called the push-pull method) can be performed most stably when the level difference between the unevenness is λA. . Regarding the width of the unevenness, in the case of a conventionally used rectangular cross section (a cross section perpendicular to the direction in which signal information bits and tracking guides are formed), the width of the unevenness is approximately 1/3 of the beam spot size of the reading laser beam. The maximum modulation depth can be obtained when the width is 0.6
Optimal track deviation detection can be performed when the width is approximately 0.8 μm. For this reason, the conventional optical information storage medium-1 in which the concavo-convex shape of the cross section perpendicular to the direction in which the signal information bits and tracking guides are formed is rectangular.
As shown in Figure 1, the depth is λ/4 and the width is about 1/3 of the beam spot size of the reading laser beam (e.g.
0 for a beam spot size of about s ~ 1.6 μm
．． A signal information bit 1 with a width of approximately 3 to 0.5 μm) is provided, and a depth of λA and a width of 0.6 to 0.5 μm is provided to enable optimal tracking deviation detection.
A tracking guide 2 having a width of about 8 μm is provided. It should be noted that various information is to be stored on such an optical information storage medium, for example, by providing information bits 3 coded as pits on the tracking guide 2. Note that the depth of this information bit is set to a value that provides the maximum modulation degree, for example, λ/4.

By the way, let's take a look at the light reflection intensity at positions along the track of the optical information storage medium.A, characteristics as shown in FIG. 2 can be obtained. In the figure, 1.1 is the light reflection level from the flat surface F (see Figure 1), and I4
is the light reflection level on tracking guide 2)
, L3 is the light reflection level from No. 48 information pit 1, and L4 is the light reflection level from information bit 3 in which various information is recorded. As is clear from Figure 2,
In such an optical information storage medium, the light reflection level L3 from the signal information bit 1 and the light reflection level L4 from the information bit 3 are both low, and the difference between them is not so large. Therefore, when reading information with an optical head and electrically processing the photoelectrically converted signal,
There is a problem in that it becomes difficult to distinguish between the signal information bit 1 and the information bit 3, making it impossible to read the information accurately.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned circumstances, and provides an optical information storage in which signal information bits and information bits recording various other information can be easily distinguished when information is read by an optical head. The purpose is to provide a medium.

[Summary of the invention]

The present invention forms a signal information bit so as to have a reflectance higher than that of light from a tracking guide,
The present invention is characterized in that it is possible to easily distinguish between signal information bits and information bits on which other information is recorded when reading information with an optical head.

[Embodiments of the Invention] The optical information storage medium of the present invention will be described below with reference to the drawings.

FIG. 3 is a schematic perspective view showing the first embodiment of the present invention. In the figure, 5 is a recording layer provided on a not-illustrated substrate made of synthetic resin or the like. This recording layer 5
A thin metal film such as TerSe is generally used as a material, and has a low melting point and low boiling point.

It satisfies conditions such as low thermal conductivity. In this recording layer 5, a tracking guide 6 and signal information bits 7 are formed in a row in a concentric or snoquil shape. The signal information bit 7 is formed to have a reflectance higher than that of the tracking guide 6 when information is read by the optical head. To do this,
You can change the width of the signal information bit and tracking guide as appropriate to set the height difference in reflectance, or set the depth of the signal information bit to nλ with respect to the depth of the trunking guide a.
/2 (however, n iJ is 0 or a natural number). In this embodiment, the depth dimension a of the tracking guide 6 is set to λA, and the depth dimension of the signal information bit 7 is set to λ/16. In addition, tracking guide 6 and signal information bit 7
The width dimension is, for example, 06 to 0.8 μm for the reading laser beam spot size of about 0.8 to 1.6 μm, which is the same as before, so that it is optimal for stable tracking.
It is set to a certain width. Further information will then be stored on the tracking guide 6, for example by providing coded information bits 8 on the tracking guide 6. Note that the depth of the information bit 8 is generally set to a value that provides a high degree of modulation, that is, an extremely low light reflection intensity suitable for information reading by an optical head, so that light reflection from the information bit is reduced. The intensity is set to be lower than the intensity of light reflected from the tracking guide. Therefore, it is a premise of the present invention that the above conditions are satisfied even when the information bit 8 is not formed in advance and the information bit corresponding to information according to the user's preference is provided via a recording/reproducing device. . In this example,
The depth of the information bit 8 is, for example, λ/4 in order to obtain the maximum modulation depth as in the conventional case.

The light reflection intensity at positions along the track of such an optical information storage medium is as shown in FIG. In the figure, Ll is the light reflection level from the flat surface F (see FIG. 3), L2 is the light reflection level from the tracking guide 6, L3 is the light reflection level from the signal information bit 7, L4 is the light reflection level from information bit 8 in which various information is recorded. As is clear from FIG. 4, the light reflection level L3 from the signal information bit 7 is the light reflection level L! from the flat surface F! approach, information bit 8
A relatively large difference is ensured with respect to the light reflection level L4 from . Therefore, when the optical head reads information from the signal information bit 7 and the information bit 8 and electrically processes the photoelectrically converted signal, it is possible to reliably distinguish between the signal information bit 7 and the information bit 8. This makes it possible to read accurate information.

In particular, in the above-mentioned optical information storage medium, since the signal information bits 7 are provided on the tracking guide 6, relatively stable tracking can be achieved even in areas where the signal information bits 7 are connected over a long distance. It has the unique effect of being able to perform

FIG. 5 is a schematic perspective view showing a second embodiment of the present invention. Components that are the same as those shown in FIG. 3 are given the same reference numerals, and detailed explanation thereof will be omitted. A different configuration is that the depth dimension of the signal information bit 10 is O. That is, a part of the flat surface F of the recording layer 5 is used to store the signal information bit 10.
was formed. With this configuration, the light reflection intensity from the signal information bit 10 will match the light reflection intensity from the flat surface F of the recording layer, and will be equal to the light reflection intensity from the information bit 8 as in the previous embodiment. It becomes possible to make it relatively large. In particular, with this configuration, the tracking guide and the signal information bit can be formed simply by creating grooves with one type of depth dimension, making it easy to create master disks used for mass production of optical information storage media. It exhibits the unique effect of being able to manufacture the optical information storage medium and, in turn, reducing the manufacturing cost of the optical information storage medium.

The embodiments described above are merely examples, and various modifications can be made within the scope of the gist of the present invention.

For example, the depth of the signal information bit is not limited to the above embodiment, and in short, the depth of the signal information bit is made closer to nλ/2 with respect to the depth of the tracking guide. The signal information bit may be formed so as to have a higher reflectance than the reflectance of light from. Therefore, the depth of the signal information bits may be deeper than the depth of the tracking guide. In the above embodiment, the tracking guide and the signal information bit are formed by four parts, but even if they are formed by convex parts of the same size, there is no change in the characteristics of the reflected light, so it is possible to form them in this way. [Effects of the Invention] As is clear from the above description, in the optical information storage medium of the present invention, when information is read by the optical head, signal information bits and other types of information are used. This destroys the excellent effect of being able to easily distinguish the information bits from the recorded information bits.

[Brief explanation of drawings]

FIG. 1 is a schematic perspective view showing a conventional optical information storage medium;
FIG. 2 is an explanatory diagram showing the light reflection intensity at positions along the track of a conventional optical information storage medium, FIG. 3 is a schematic perspective view showing the first embodiment of the present invention, and FIG. 4 is the same diagram. An explanatory diagram showing the light reflection intensity at positions along the track of an optical information storage medium, tl) 5 is a shelf showing a second practical example of the present invention,
It is a schematic perspective view. 6... Tracking guide, 7... Signal information hit, 10... Signal information bit, F... Flat surface.

Claims (2)

[Claims] (1) An optical information storage medium that is equipped with a tracking guide for detecting track deviation and a signal information bit that stores specific signal information, and that can read at least information using condensed radar light. An optical information storage medium, wherein the signal information bit is formed to have a higher reflectance than the reflectance from the tracking guide. (2) The signal information bit is formed by a part of the flat surface of the tracking guide, which is formed by providing unevenness on the flat surface. optical information storage medium.