JPS5938944A - Optical information storing medium - Google Patents

Abstract

PURPOSE:To ensure stable tracking even at an area where signal information pits are continuous, by forming the signal information pits and a tracking guide so as to have approximately equal sectional forms which are rectangular to the forming direction of these information pits and the tracking guide. CONSTITUTION:A record layer 4 is provided on the outer surface of a substrate 3 of a synthetic resin, etc., and the layer 4 uses a thin metallic film of Te, Se, etc. The layer 4 contains a tracking guide 5 consisting of a recessed groove and signal information pits 6 which are separated from the guide 5. These guide 5 and pits 6 have the sectional forms rectangular to their forming direction, e.g., both depth and width are approximately equal among these groove and pits. In such a way, a tracking guide and signal information pits can be easily formed to a master disk of an optical information storing medium. This process reduces the production cost of an information storing medium.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an optical information storage medium in which an information layer can be embedded or read by a laser beam yLK.

[Technical background of the invention and its problems]

Compact discs (CDs) are used as information storage media, such as digital audio discs (DADs) and VCs.
) Read-only information storage media, such as image files and computer output, that are in the form of discs or tapes, as typified by °0-technical video discs, and can read a variety of information using focused laser light. memory (C
Information for recording and playback that is in the shape of a disk or tape, such as those used in OM), and that allows information to be written to and read from the recording layer using focused laser light. Examples include storage media and erasable information storage media.

Such information storage media have narrow track pitches in order to increase the density of information. For this reason, in order to make the optical head follow a predetermined track during reading or writing, this type of information storage medium is provided with a tracking guide consisting of a groove or a convex portion having a step with respect to a flat surface. It is formed. Furthermore, if the track number and sector position indicating the position where information is recorded are recorded in advance, the software for the recording/reproducing device will be easier. It is also equipped with a signal information pit consisting of 2 parts (also called a tracking guide with cryo matsuding).

The tracking guide and the signal information pit are formed by the unevenness of the flat surface, and the difference in the amount of light reflected therefrom can be read as information. For this reason, the tracking guide is designed to have a depth of, for example, λ/8 (λ is the original wavelength of the reading laser) in order to increase the tracking signal due to the original diffraction pattern reflected from the guide and to enable stable tracking. (The same applies hereafter), and is a rectangular groove with a width of about 0.6 to 0.8 μm. In addition, the signal information pit has a depth of λ so that it can have the maximum modulation degree (when the reading laser source is irradiated directly above the signal information pit, the light reflection intensity from there is the smallest). /4, and the width is set to about 176, which is the spot size of the reading laser beam.

By the way, as shown in the sectional view K of FIG. 1 (schematic sectional view along a tracking guide with preformatting of a conventional optical information storage medium), there is a structure in which the tracking guide 1 and the signal information pit 2 are separated. In this case, tracking must also be performed using the diffracted light pressure from the signal information pit 2 having a depth of λ/4. However, such tracking lacks stability, and there is a problem in that tracking becomes extremely unstable, particularly in areas where information pits are continuously connected over a long distance.

[Purpose of the invention]

The present invention has been made in consideration of the above-mentioned circumstances, and in a structure in which the signal information pits and the tracking guide are separated, stable tracking can be performed even in a part where the signal information pits are connected. The purpose is to provide optical information storage media.
change.

[Summary of the invention]

Present invention Ub) In an optical information storage medium that is equipped with a racking guide and a signal information pit and can read at least information from a focused laser source, the signal information pit and the tracking guide are The cross-sectional shape perpendicular to the direction of formation of is substantially the same.

[Embodiments of the invention]

The present invention will be explained below with reference to the drawings.

The second (2) is a tracking guide V with preformatting for an optical information storage medium, which is an embodiment of the present invention.
It is a sectional view along C. In the figure, 3 is a substrate made of synthetic resin or the like, and a recording layer 4 is provided on its outer surface. For this recording layer 4, a metal thin film such as Te or 5S is generally used, and satisfies conditions such as a low melting point, a low boiling point, and a low thermal conductivity. The recording layer 4 has a tracking guide 5 formed of, for example, a groove.
and a signal information pit 6 separated from this.

Here, the step size kK of the tracking guide 5 and the signal information pit 6 with respect to the flat surface P1 of the recording layer 4
This will be explained (see Figure 2). First, it is considered optimal that the step size is within the range shown by the first equation. However, in the first equation, λ is the original wavelength of the reading laser;
is 0 or a natural number.

This is because first, when the tracking guide or signal information is n, the light reflection level is the lowest, and when h=varnish, it matches the light reflection level from a flat surface. Therefore, in terms of light reflection intensity, the step size is preferably in the range of ■λ to Aλ. Next, it is necessary to make it possible to obtain a track detection signal by the diffraction pattern of the reflected light from the tracking guide and the signal information pit, so the step dimension is not extremely close to the value of -λ or 11λ. This is essential. Therefore, the first equation is derived as the optimal range of the step size that satisfies the above two conditions.

Further, the tracking guide 5 and the signal information bit 6
This means that the cross-sectional shapes perpendicular to the direction in which they are formed, such as grooves and holes, have approximately the same depth and width. In particular, by forming the optical information storage medium in this way, it is possible to easily provide a tracking guide and signal information bits on the master disc for manufacturing the optical information storage medium, which in turn makes it possible to reduce the manufacturing cost of the optical information storage medium. It becomes possible.

It should be noted that various information will be stored on such an optical information storage medium, for example by providing information bits 7 coded as pits on the tracking guide. The depth of this information bit 7 is set to, for example, λ/4K, which provides the maximum modulation degree.

Next, regarding the optical information storage medium, the light reflection intensity at positions along the track VC will be explained based on FIG. 6.

In the figure, Ll is the light reflection level from a flat surface l),
L2 is the light reflection level on the tracking guide,
L3 is the light reflection level from the signal information bit, L
4 is the light reflection level from the portion where other information is recorded in the recording layer (ie, the information bit 7). As is clear from FIG. 3, since the light reflection level L3 from the signal information bit is lower than the light reflection level Ll from the flat surface, and n becomes the signal. In addition, the light reflection level L4 from the part (information bit 7) where other information is recorded on the recording layer is the light reflection level L from above the tracking guide.
Since it is lower than 2, this n will be detected as a signal. Further, since the step dimensions of the signal information bit 6 and the tracking guide 5 are within the range shown by the first equation, it is possible to obtain a track error n detection signal from the diffraction pattern of the reflected light from these bits. Therefore, stable tracking is possible even in a portion where the signal information bits 6 are continuous over a long distance.

Note that the above-mentioned embodiment is merely an example, and various modifications can be made within the scope of the gist of the present invention. For example, signal information bits and tracking guides are not limited to holes or grooves, but can be formed by convex portions. In addition, the cross-sectional shape of signal information bits and tracking guides [
It can be made into an appropriate shape such as a rectangular shape or a U-shape.

〔Effect of the invention〕

As is clear from the above description, in the optical information storage medium of the present invention, even if the signal information bit and the tracking guide are separated from each other, This has excellent effects such as stable tracking.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view along a tracking guide with preformatting of a conventional optical information storage medium, and FIG. 2 is a schematic sectional view of an optical information storage medium with preformatting according to an embodiment of the present invention. FIG. 6 is a cross-sectional view of the tracking guide Kfi, and is an explanatory diagram showing the light reflection intensity at a position along the track of the optical information storage medium of the present invention. 3...Substrate, 4...Recording layer, 5...Tracking guide, 6...Signal information bit. Agent: Ben 31st Nori Chika Kensuke (and 1 other person) No. II
Written amendment to related proceedings (spontaneous) Showa A, 32318 Kazuo Wakasugi, Commissioner of the Japan Patent Office 1, Indication of the case Patent Application No. 1983-146860 2, Name of the invention Optical information storage medium 3, Person making the amendment Relationship with the case Patent Applicant (307) Tokyo Shibaura Electric Co., Ltd. 4 Agent 1-1-6 Uchisaiwai-cho, Chiyo F13-ku, Tokyo 100 Tokyo Shibaura Electric Co., Ltd. Tokyo Office Interior 6 Contents of amendment (1) Page 8 of the specification In line 9, change [・niso] to “・・
"A hole in the hole," he corrected. (2) "1 Other information..." on page 8, line 10 of the specification is corrected to "Information..." by opening 1-. (3) In the 8th line, 10th line of the specification, “...Karari 1”
...Well then," he corrected. (4) In line 8 of the specification, the 11th line, "...Level L4 is Tiger..." is corrected to "...Level L4 is Tiger...". (5) Figure 2 of the drawings will be corrected as shown in the attached sheet. that's all

Claims (1)

[Scope of Claims] (j) In an optical information storage medium, the optical information storage medium comprises a tracking guide and a signal information bit; The tracking guide is a Kuban-type information storage medium characterized by having a cross-sectional shape that is perpendicular to the direction in which they are formed, or is formed almost equally. (2) The tracking guide and signal information bit (-'
! Claim 1, characterized in that it has a step in the range of -thi+yu)λ (where) is R shift, 810 wavelength of the original source, and le is 0 or a natural number). The optical information storage medium according to item 1.