JPH03254437A - Optical information recording medium - Google Patents

Abstract

PURPOSE:To make improvement in the transferability of prepits by forming the non-forming parts of guide grooves in the whole or a part of the regions inclusive of the parts adjacent to the prepit arrays among the guide grooves. CONSTITUTION:A substrate 1 is formed by an injection molding method. The guide grooves 2 and the prepits 3 are transferred thereto simultaneously with the injection molding of the substrate 1. The guide grooves 2 are not continuously formed but the non-forming parts 2a of the guide grooves are formed in the whole or a part of the regions inclusive of the parts adjacent to the prepit arrays 3. Namely, a stamper from which the projections of the parts corresponding thereto are removed is used to prevent the generation of disturbance in the flow of the resin flowing to the circumference of the projecting parts for the prepits by the projecting parts for the guide grooves. The transferability of the prepits is improved in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical information recording medium, and more particularly to the shape of a guide groove in an optical information recording medium in which a pre-pit array is formed between adjacent guide grooves. .

[Conventional technology]

Conventionally, as shown in FIGS. 10 and 11, there has been known an optical information recording medium in which pre-pit rows 12 are formed between guide grooves 11 formed at equal intervals (Japanese Unexamined Patent Application Publication No. 1983-1999).
No. 41446).

This optical information recording medium is characterized in that since the track signal read from the guide groove 11 is not superimposed on the information signal read from the pre-pit row 12, a read signal with a high S/N ratio can be obtained. It is attracting attention as a recording method for magneto-optical recording media, etc., which reads minute changes in the Kerr rotation angle as information signals.

[Problem to be solved by the invention]

By the way, the guide groove 11 and prepit row 12 are transferred onto one side of the substrate by a transfer technique. The method for transferring the guide grooves 11 and pre-pit rows 12 is as follows: (1) uniformly spreading a photocurable resin between the substrate and a stamper having a concavo-convex pattern that is reversed with respect to the desired guide grooves 11 and pre-pit rows 12; A method (2P method) of peeling off the photocurable resin from the stamper after stretching and curing the resin to form a resin layer having guide grooves 11 and prepit rows 12 transferred onto one side of the substrate (2P method); is formed into the shape of a desired substrate, and a part of the cavity surface is formed by the stamper, and injects and fills the mold with molten resin;
There is a method (injection molding method) of integrally molding a substrate having desired guide grooves 11 and pre-pit rows 12 on one side.

The injection molding method is characterized by much higher productivity than the 2P method, and now that optical information recording media have reached the mass production stage, establishing this technology is the most important technological This is one of the challenges.

However, as mentioned above, the pre-pit row 1 is formed between the guide grooves 11.
When an optical information recording medium having the above-mentioned number 2 is manufactured by the injection molding method, the transferability of the pre-pits 12 is poor, making it difficult to manufacture a normal optical information recording medium.

As a result of research into the causes of such defects, the inventors of the present application have obtained the following knowledge. That is, as shown in FIG. 12, the stamper 13 is formed with a guide groove protrusion 14 which is an inverted pattern of the guide groove 11 and a prepit protrusion 15 which is an inverted pattern of the prepit 12. When the molten resin 16 is injected at high speed from one side of the stamper 13, the molten resin 16 that advances inside the cavity along the stamper 13 collides with the guide groove protrusion 14, creating a turbulent flow and entraining air. When air entrainment occurs in this way, the width w1 of the guide groove protrusion 14 and the pre-pit protrusion 1
5 has a width Wz of about 0.4 μm to 0.8 μm, and a height hx of the guide groove protrusion 14 and a depth hz of the pre-pit protrusion 15 are about 61 nm to 138 nm or an integral multiple thereof (however, the reproduction light The wavelength of the substrate is 830 nm, and the refractive index of the substrate is 1.
．． 5>, the interval (track pitch) P between the two adjacent guide groove protrusions 14.14 is approximately 166 μm.
Since the resin is extremely fine, the resin does not sufficiently wrap around the prepit protrusion 15 side, especially the back side of the prepit protrusion 15, and normal prepit transfer is inhibited.

The present invention eliminates the deficiencies of the prior art described above.

An object of the present invention is to provide an optical information recording medium that can transfer pre-pits with high precision using an injection molding method.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides an optical information recording medium in which pre-pit rows are formed between guide grooves formed at equal intervals. In all or part of the area including the part adjacent to the pre-pit row in parallel,
A portion where the guide groove is not formed is provided.

[Effect]

In order to injection mold such an optical information recording medium, it is necessary to use a stamper in which all or part of the region of the guide groove protrusion including the portion adjacent to the pre-pit protrusion has been removed. When this stamper is installed in a mold and molten resin is injection molded, the flow of resin flowing around the pre-pit protrusion is not disturbed by the guide groove protrusion, so the so-called sprue is improved, and air is removed. The entrainment is reduced and the transferability of the pre-pits is improved. As a result, an optical information recording medium on which pre-pits are transferred with high precision can be provided at a low cost.

〔Example〕

First, an outline of the present invention will be explained based on FIGS. 1 to 4.

FIG. 1 is a sectional view of an optical information recording medium according to the present invention, FIG. 2 is an enlarged sectional view of FIG. 1, FIG. 3 is a plan view of this optical information recording medium, and FIG. 1 is a sectional view showing a cross-sectional shape, and 1 is a substrate, 2 is a guide groove, 3 is a pre-pit, and 4 is a recording film.

The substrate 1 is made of, for example, acrylic resin such as polycarbonate or polymethyl methacrylate.

Polyolefin resins such as polymethylpentene, polysulfone, polyethersulfone, polyarylate, etc.
It is made of transparent thermoplastic resin, and the guide groove 2 and pre-pit 3 are integrally formed on one side thereof.

This substrate 1 is formed by injection molding, and the guide grooves 2 and pre-pits 3 are transferred simultaneously with the injection molding of the substrate 1.

The guide groove 2 is formed in a concentric or spiral shape in a planar direction of the substrate l. Further, the pre-pit 3 is a second pre-pit.
As shown in the figure and Fig. 3, two adjacent guide grooves 2
, 2. The guide groove 2 is not formed continuously, but in all or part of the area including the part adjacent to the pre-pit row 3, there is a non-forming part 2a of the guide groove.
is formed. The cross-sectional shapes of each prepit constituting the guide groove 2 and the prepit row 3 are shown in FIGS. 4(a) to 4(d).
As shown in Figure 7, U-shape, rectangle, or trapezoid, etc.
It can be formed into any shape.

The depth dl of the guide groove 2 can be formed to any desired depth, but in order to strengthen the contrast of the readout light in the detector and obtain a high S/N, the wavelength of the reproduction light is set to λ, and the refractive index of the substrate is adjusted. If n is λ/8 n or λ/6
It is preferable to form the number n or an integral multiple of λ/4n. Although the width wi of this guide groove 2 can be formed arbitrarily, it is preferably formed to be 0.4 μm to 0.8 μm in view of the need for improving recording density. Two adjacent guide grooves 2, 2
The pitch p is approximately 1.6 μm. Moreover, the depth d3 and width w2 of the pre-pit 3 are also formed in the same range as the guide groove 2.

Hereinafter, the arrangement of the guide groove-free portions 2a with respect to the pre-pit rows 3 will be explained based on FIGS. 5 to 8.

The guide groove non-forming portions 2a can be formed in an arbitrary arrangement in all or part of the region including the portion adjacent to the pre-pit row 3.

For example, as shown in FIG. 5(a), it may be formed in a portion adjacent to the prepit row 3 over the same length as the length 1 of the prepit row 3;
As shown in Figure (b), the pre-pit rows 3 may be provided in a range slightly longer than the length 1 in the same portion.

In addition, as shown in FIGS. 6(a) and 6(b), among the prepits constituting the five prepit rows 3, an address signal pit row 3a is formed by a combination of pits that are usually longer than other prepits. It is also possible to form the guide groove non-forming portion 2a only in the adjacent portion. In this case, as shown in FIG. 6(a), the guide groove non-forming part 2a can be formed over the same length as the length I12 of the address signal pit row 3a, or As shown in FIG. 6(b), the guide groove non-forming portion 2a may be formed over an area slightly longer than the length IlZ of the address signal pit row 3a. The non-formed portion 2a of the guide groove is set to the length fiz of the address signal pit row 3a.
If the area is provided over a slightly longer range than the address signal pit row 3a, it may be formed to have a length that is the sum of the length of the non-pit forming area (land area) 5 placed before and after the address signal pit row 3a, plus I23. can.

Further, as shown in FIGS. 7(a) and 7(b), of the pre-pits constituting the address signal pit row 3a, the guide groove non-forming portion 2a is formed only in the portion adjacent to the sector mark signal pit row 3b. It can also be formalized. in this case,
As shown in FIG. 7(a), the non-forming portion 2a of the guide groove can be formed to have the same length as the length I14 of the sector mark signal pit row 3b. )
As shown in FIG. 3, the guide groove non-forming portion 2a may be formed over an area slightly longer than the length I14 of the sector mark signal pit row 3b. When the length of the non-forming part 2a of the guide groove is provided over a range slightly longer than the length I4 of the sector mark signal pit row 3b, lands arranged before and after the sector mark signal pit row 3b The length can be the sum of the length I13 of the portion 5.

Further, as shown in FIGS. 8(a) and 8(b), the guide groove-free portions 2a may be formed only in portions adjacent to the individual pits 3C constituting the pre-pit row 3a. In this case, as shown in FIG. 8(a), the guide groove-free portions 2a may be formed at positions adjacent to all the pits 3C, or as shown in FIG. 8(b), The non-forming portion of the guide groove is selectively formed only in a region including a portion adjacent to a relatively long prepit, for example, a prepit having a pit length of 1 μm or more, among the prepits constituting the prepit row 3a. You can also do that.

Of course, in this case as well, the non-formed portion 2a of the guide groove can be made to have the same length as each pre-pit 3C, or can be formed longer than each pre-pit 3C.

In each of the above-mentioned embodiments, the guide groove non-forming portion 2 is provided on both of the guide grooves located on both sides of the pre-pit row 3.
Although the gist of the present invention is not limited to this, for example, as in a CLV (Constant Linear Velocity) type optical information recording disk, the pre-pit forming portion is formed in the radial direction of the disk. In an optical information recording medium that is not aligned, it is also possible to form the guide groove-free portion 2a only in the guide groove 2 located on the side where resin is injected with respect to the pre-pit row 3 during molding.

The recording film 4 is made of, for example, a low melting point metal such as TeSe, an organic dye containing a certain kind of dye, TeFeCo, Gd
Magneto-optical recording materials such as TbFe, TeDyFe-GdCo, TbFe, or TeOx, As-Te-Ge
It can be formed using any known heat mode recording material such as a phase change recording material such as.

Examples of methods for forming the recording film 4 include vacuum evaporation, sputtering, ion blasting, electroless plating,
Appropriate thin film forming means such as plasma deposition or spin code method can be applied.

Next, four specific examples will be listed and the effects of the present invention will be mentioned. 1st Example By injection molding polycarbonate (optical grade), a guide groove having a non-formed part in a part, Diameter 130mm, plate thickness 12mm with pre-pit rows transferred
A substrate was fabricated. The guide groove has a depth of approximately λ/8
n, a triangular groove shape with a width of approximately 0.6 μm, and a pitch of approximately 1.
It formed into a spiral shape of 6 μm. The pre-pit row had a rectangular groove shape with a depth of about λ/4n and a width of about 0.6 μm, and was arranged between the guide grooves. The portion where the guide groove is not formed is formed at a position adjacent to a portion of the prepit row from the start end to the end of the sector mark signal pit row consisting of a plurality of sector mark signal pits (see FIG. 7(a)). did.

The molding conditions for the substrate were a cylinder temperature of 350° C., a mold temperature of 100° C., and an injection speed of 150 mm/sec.

The injection pressure was 1500 kg/ci.

Next, a tellurium-based recording film was sputtered onto the surface of this substrate on which the guide grooves and pre-pit rows were formed, thereby producing an optical information recording disk.

Second Embodiment In an optical information recording disk similar to the first embodiment,
The non-formed portion of the guide groove is placed at a position adjacent to the portion from the start end to the end of each sector mark signal pit (see Fig. 8).
b)).

The material of the substrate, the injection molding conditions, the shapes and dimensions of the guide grooves and pre-pits, the recording film material and the method of forming the same are the same as in the first embodiment.

Third Embodiment In an optical information recording disk similar to the first embodiment,
The guide groove is a rectangular groove with a depth of approximately λ/6 n and a width of approximately 0.6 μm, and the pre-pit row also has a depth of approximately λ/6 n.
, was formed into a rectangular groove with a width of about 0.6 μm. In addition, the non-forming part of the guide groove is located at a position adjacent to the part of the pre-pit row from the start end to the end of the sector mark signal pit row consisting of a plurality of sector mark signal pits (see FIG. 7(a)).
was formed.

The material of the substrate, the injection molding conditions, the recording film material and the film forming method thereof are the same as in the first embodiment.

Fourth Embodiment In an optical information recording disk similar to the third embodiment,
The non-formed portion of the guide groove is placed at a position adjacent to the portion from the start end to the end of each sector mark signal pit (see Fig. 8).
b)).

The material of the substrate, the injection molding conditions, the shapes and dimensions of the guide grooves and pre-pits, the recording film material and the method of forming the same are the same as in the third embodiment.

FIG. 9 shows a pre-pit signal waveform read from the optical information recording disk of each of the embodiments described above and a pre-pit signal waveform read from a conventional optical information recording disk in which guide grooves are continuously formed. FIG. 9(a) shows the pre-pit signal waveform read from the optical information recording disk of each of the above embodiments, and FIG. 9(b) shows the pre-pit signal waveform read from the conventional optical information recording disk, both of which are horizontal. The axis is time and the vertical axis is the read signal level.

The readout conditions are NA 0.5, laser wavelength 83.
A reproduction drive with a wavelength of 0 nm and a reproduction laser power of 1.0 mW was used, and the rotation speed was 120 rpm.

As is clear from this graph, signals read from conventional optical information recording media have waveform distortion.

In addition, although the signal amplitude is small, the signal read from the optical information recording disk of the present invention has no waveform distortion, and the signal amplitude is almost the same as the theoretical one. From this, it can be seen that the optical information recording medium of the present invention has ideal pre-pit transferability. In the case of conventional optical information recording media, the amount of distortion in the signal waveform becomes more significant as it approaches the outer periphery of the disk.At a radius of 30 mm from the center of the disk, the amount of waveform distortion is about 50%, while at a radius of 60 mm from the center of the disk At the position mm, the amount of waveform distortion reaches approximately 70%. In contrast, in the optical information recording medium of the present invention, the amount of distortion of the signal waveform is O
Met.

Although each of the above embodiments has been explained using an optical information recording disk as an example, the gist of the present invention is not limited thereto, and can be applied to other optical information recording media such as an optical cart. Of course.

〔Effect of the invention〕

As explained above, according to the present invention (7), a stamper in which all or part of the region of the guide groove protrusion including the portion adjacent to the pre-pit protrusion is removed is used during injection molding of the substrate. Since the flow of resin flowing between the circumferences of the pre-pit protrusions is not disturbed by the guide groove protrusions, the pre-pit transferability is improved. Therefore, the waveform distortion of the signal read from the pre-pits is improved, and it is possible to read the pre-pit signals, reduce errors, and improve the S/N ratio.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of the optical information recording medium according to the present invention, FIG. 2 is an enlarged cross-sectional view of FIG. 1, FIG. 3 is a plan view of the optical information recording medium of FIG. 1, and FIG. Figures (a) to (d) are cross-sectional views illustrating the cross-sectional shapes of guide grooves and pre-pits, No. 512
J (a) (b), Figure 6 (a) (b), Figure 7 (a) (
b'), 8th? ]! :a) (+)) is a plan view of the main part illustrating the arrangement of the non-formed part of the guide groove, Section 9, □□□ (,) (b) is a graph showing the effect of the present invention. Main part plan view of a conventionally known optical information recording medium, 1st
FIG. 1 is a sectional view of the optical information recording medium shown in FIG. 10, and FIG. 12 is an explanatory diagram showing problems with the conventional optical information recording medium. Substrate, 2: Guide groove, 2a: Non-formed area, 3: Pre-pit row, 4: Recording film Figure 4 Figure 2 (3) 2-3 rattan diagram! Substrate 2, work Circular groove 2σ: wr @ 3 ゛ Burihibi Lido 4 Tomiko ±2 Ukisho Figure 6 Figure 8 Figure 7 (0) (b) Engraving (b) Time Figure 0 Procedure correction Type (Method) % Formula % Indication of the case Name of patent application patent invention Person who amends the optical information recording medium Relationship with the case No. 1-313360

Claims (8)

[Claims] (1) In an optical information recording medium in which a pre-pit row is formed between guide grooves formed at equal intervals, all or part of the area of the guide groove including a portion adjacent in parallel to the pre-pit row . An optical information recording medium characterized in that a portion where the guide groove is not formed is provided. (2) The optical information recording medium according to claim 1, wherein the portion where the guide groove is not formed is provided in a region of the pre-pit row that includes a portion adjacent to the address signal pit row. Medium. (3) The optical information recording medium according to claim 1, wherein the portion where the guide groove is not formed is provided in an area including a portion of the address signal pit string adjacent to the sector mark signal pit string. Information recording medium. (4) The optical information recording medium according to claim 1, wherein the portion where the guide groove is not formed is provided in an area including a portion adjacent to each prepit forming the prepit row. Medium. (5) In the optical information recording medium according to any one of claims 1 to 4, the portion where the guide groove is not formed is formed in one of the portions adjacent to the individual prepits constituting the prepit row.
An optical information recording medium characterized in that the optical information recording medium is provided in an area including a portion adjacent to a pre-pit having a pit length of .mu.m or more. (6) In the optical information recording medium according to any one of claims 1 to 5, of the two guide grooves adjacent to the prepit row, the guide groove is located on the upstream side of the resin flow from the prepit row during injection molding of the substrate. An optical information recording medium characterized in that the non-forming portion is provided only in the guide groove arranged in the guide groove. (7) In the optical information recording medium according to any one of claims 1 to 6, the portion where the guide groove is not formed is formed by forming the pre-pit row, the address signal pit row, the sector mark signal pit row,
Alternatively, an optical information recording medium characterized in that the length is the sum of the length of each pit and the length of land portions arranged before and after these pits. (8) In the optical information recording medium according to any one of claims 1 to 7, the cross-sectional shape of the guide groove may be V-shaped, U-shaped,
An optical information recording medium characterized by being formed into a rectangle or an inverted trapezoid.