JPH08287526A - Production of optical master disk - Google Patents

Abstract

PURPOSE: To improve a yield by making the rainbow color display or hologram display by the reflected and diffracted light from diffraction gratings common as a background and composing the process of a stage for forming a spare stamper and a stage by a laser marker method. CONSTITUTION: The dummy pit forming regions of the spare stamper 61 are selectively continuously irradiated or scanned and irradiated with a laser beam 64 according to the main display patterns of, for example, characters, symbols, pictures, etc., which are the main subject material, by which the prescribed dummy pits are melted and are crushed to form shallow recessed parts, the main patterns are plotted directly in the dummy pit strings and an optical master disk 62 is directly formed. The main display pattern parts are irregular reflection parts where reflection and diffraction do not arise. As a result, the optical master disks of the diversified main display patterns are formed from the stamper for background commonly using the optical master disk and are formed with a smaller number of stages.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an optical disk master, and more particularly to a method for manufacturing an optical disk master for a reflection type optical disk composed of translucent circular substrates bonded to each other.

[0002]

2. Description of the Related Art Generally, in an optical disc, a CD is read by irradiating a laser beam from only one side.
In the single plate disc as described above, the identification display of the recorded content is based on a visible print pattern or label on the protective film on the back side of the recording surface. A digital video disc (hereinafter referred to as a DVD) in which a pair of discs each having an information recording area on a transparent substrate are bonded on the information recording area side,
There is also a laminated double-sided type such as a laser disk (hereinafter referred to as LD). Also on this double-sided type optical disc, a recorded content is displayed with a label and a print pattern.

Further, as to an optical disk manufacturing method in which a label and a print pattern are displayed in an external process, for example, as disclosed in Japanese Patent Publication No. 5-797, a label area and an information recording area around a center hole of the optical disk. There is a method in which a visible character pattern or the like is formed inside the disc in the information non-recording area adjacent to the area. However, since the pattern display area area is small and narrow between such a label area and the information recording area, especially in a small high-density optical disk such as a DVD, it is not possible to display a sufficiently large pattern and the display information amount is limited. Has been done.

Further, as disclosed in Japanese Utility Model Application Laid-Open No. 2-30126, a method of forming a hologram pattern in an information non-recording area adjacent to an information recording area, that is, a display pattern is recorded in advance on an optical disc master, a so-called stamper. There is also a method of forming it together with the region and displaying it in an internal process, but similarly, the display information amount is limited.

On the other hand, in a conventional method of manufacturing a stamper for mass-producing optical disks, a method of forming a predetermined pattern of sequential or scanning exposure and etching on a photoresist layer is used. As a method of manufacturing an optical disk stamper, first, as a laser cutting process, a resist substrate having a positive resist layer uniformly formed on the main surface of a glass substrate is rotated, and a laser beam modulated according to a predetermined signal is used as a substrate. By moving in the radial direction, a latent image of a minute spot array corresponding to predetermined information is formed on the resist layer in a spiral or concentric pattern at a predetermined track pitch, and the sequentially exposed resist substrate is developed, and the resist layer is dried and fixed. (Post-baking) A substrate having recesses corresponding to signals to be recorded is obtained on the resist substrate.
Next, as an electroforming step, a metal is laminated as a conductive film on the resist layer. The base with a conductive film is immersed in an electroforming tank to form a thick metal layer, that is, a stamper on the conductive film. Here, in the case of continuous irradiation of the laser beam, the concave portion becomes a pre-groove, and in the case of intensity modulation which causes blinking, it becomes a pit row.
(Hereinafter, pregrooves and pits are also collectively referred to as pits) Finally, the stamper is separated from the glass substrate, and the resist layer and conductive film remaining on the stamper are removed to obtain the stamper.

An optical disk replica having a predetermined information recording surface is produced by an injection molding device using this stamper. An optical disc is formed by forming a reflective layer on the information recording surface of the obtained replica and further forming a protective film on the reflective layer.

[0007]

Here, in the conventional method for manufacturing an optical disk master, as described in Japanese Patent Publication No. 5-797, the information is recorded on the photoresist layer in the laser cutting process. A display pattern is recorded, and a stamper is created by a developing and electroforming process. When the display pattern is formed in the laser cutting process as described above, there arises a problem that the manufacturing yield of the stamper is lowered. Furthermore, in a small-diameter optical disk such as a DVD, the display area is small, and a sufficient pattern display portion cannot be provided.

Therefore, an object of the present invention is to provide a method of manufacturing an optical disk master having a high yield and capable of displaying a clear and large pattern such as a large character.

[0009]

According to the method of manufacturing an optical disc master according to the present invention, one of the recording surfaces has a recording track formed in a concentric circle shape or a spiral shape consisting of a pit row carrying an information signal, and the recording surface. The other has a diffraction grating area that produces diffracted light by incident light and a display pattern area that is formed in the diffraction grating area and does not produce diffracted light by the incident light.Pit rows are formed on both recording surfaces. A method of manufacturing an optical disk master for a reflective optical disk to be obtained, comprising: forming a spare optical disk master having the diffraction grating area on a main surface; and the display pattern in the diffraction grating area of the spare optical disk master. And a step of removing only a portion corresponding to the region.

In the above optical disc master manufacturing method, the diffraction grating region may be a hologram, or a dummy pit row or a pre-groove formed spirally or concentrically at a predetermined pitch, or in parallel straight lines at a predetermined pitch. preferable.

[0011]

According to such a method for manufacturing an optical disk master, in the method for manufacturing an optical disk, for example, a group of steps for forming a partial pattern as a background by making rainbow color display or hologram display by reflection and diffracted light from a diffraction grating common. Since it is composed of a process group for individually forming the pattern part of the main subject on the background, it is not necessary to perform laser cutting for each pattern as in the conventional case, and the background display pattern (preliminary having a diffraction grating area) Since an optical disk master, that is, a stamper, can be used in common, the stamper in which the main subject display pattern is formed in the background display pattern can be easily manufactured by duplicating and using the pattern in the electroforming process.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method of manufacturing an optical disk and an optical disk master according to an embodiment of the present invention will be described below with reference to the accompanying drawings. (Reflective Double-sided Optical Disk) As shown in FIG. 1, the optical disk 42 of the embodiment is a double-sided type optical disk in which the information recording disk portion 12 and the dummy disk portion 11 are joined together via the adhesive layer 5.

The information recording disk section 12 has a circular substrate 8 formed on one side of a plurality of information pits 10 forming a concentric circular or spiral recording track for carrying an information signal, and a substrate 8 thereof. Metal reflective layer 7 formed on the information pit forming surface of the above, and a protective film 6 covering the reflective layer 7.
It consists of and. The dummy disk unit 11 includes a circular substrate 2 having a plurality of pits having no relation to information signals, that is, dummy pits 9 formed as a pit group on one surface,
It is composed of a metal reflection layer 3 formed on the dummy pit formation surface of the substrate 2 and a protective film 4 covering the reflection layer 3. The dummy pit 9 is formed in order to obtain a vivid rainbow color generated by reflected diffracted light.

Two circular substrates 2 and 8 having the same circular size are
A double-sided optical disk 42 made of a transparent synthetic resin or the like and bonded by an adhesive layer 5 between the protective films 4 and 6 formed on one surface of each disk portion.
Are formed. In both disc parts, the pre-pits and dummy pits corresponding to the data to be reproduced are already injection-molded (injection-molded) on the plastic substrate.

The substrate is not limited to an integrally formed injection-molded resin substrate, but a so-called 2P (photo-polymer) is used, in which a fluid ultraviolet curable resin is formed on a transparent substrate as a transfer layer such as a pre-groove. The substrate may be formed by the method). The transparent substrate material in the present invention, acrylic resin such as polymethylmethacrylate (PMMA), polycarbonate (PC), polyvinyl chloride, polyimide, polyamide, cellulose triacetate, in addition to polymeric materials such as polyethylene terephthalate, glass and ceramics And so on.

Examples of the material for the reflective layer in the present invention include metals with high reflectance such as gold (Au), copper (Cu), aluminum (Al), and alloys thereof. For example, a vacuum deposition method, a sputtering method, The reflection layer can be formed by the ion plating method. The protective film in the present invention is formed by spin-coating an ultraviolet curable resin and applying it, and then irradiating it with ultraviolet rays to cure the coating film. In addition, epoxy resin, acrylic resin, silicone resin,
Urethane resin or the like is used as the protective film material. Also,
The protective film may be omitted if the reflective layer has durability.

As the adhesive layer in the present invention, an adhesive such as a hot melt adhesive, an ultraviolet curable resin, a rubber adhesive, a urethane adhesive, an epoxy adhesive, a roll coat method, a spin coat method, It can be used by a screen printing method or the like. In addition, in the present invention, in addition to the ROM type reflection type optical disc in which the information recording disc portion 12 having the information recording area of the above-mentioned embodiment is a prepit and a reflection film,
The recording layer of the information recording area may be, for example, a write-once type optical disc made of a light absorbing film made of a cyanine organic dye and a metal film, or a phase change type optical disc made of a metal alloy film making a crystalline-amorphous phase change. . Further, it may be a magneto-optical disk including a recording layer of a rare earth-transition metal amorphous alloy and a dielectric layer. As a method of forming this information recording area, a sputtering method, a vacuum vapor deposition method or the like can be appropriately used.

As is apparent from the perspective view of the main part of the optical disc of the present invention shown in FIG. 2, the optical disc 42 has a pit formation region 42a in which pits are formed and a non-information recording region 4
It is divided into 2b. In the pit formation area 42a of the substrate 2 of the dummy disk portion 11, a pattern display area P representing the character "A" is surrounded by a group of dummy pits.
The dummy pit group is not formed in the character pattern portion "A", but is formed in the portion excluding the character pattern. That is, the pattern display area P of the pattern of the character "A" is a mirror surface. As shown in the figure, the dummy pit group is formed not only around the pattern display area P but also over the entire recording surface of the dummy disk portion 11. In addition,
The arrow R in the figure indicates the radial direction of the disk.

On the recording surface of the dummy disk portion 11 of the optical disk 42, reflected diffracted light is generated in the portion where the dummy pit 9 is formed, but reflected diffracted light is not generated in the mirror surface portion where the dummy pit 9 is not formed. Therefore, the display pattern becomes visible depending on the presence or absence of the reflected diffracted light. Further, a group of dummy pits may be formed inside and outside the pattern display area P, and the depth or density of the dummy pits formed inside the pattern display area and the dummy pits formed outside the pattern display area may be different. In such a case, since the intensity or the diffraction angle of the reflected diffracted light is different inside and outside the pattern display area, the pattern becomes visible.

In the above embodiment, the character is shown by the non-formed portion surrounded by the dummy pit group, but the character is not limited to the character. For example, it is possible to form patterns such as graphics and photographs showing the contents of the information signal recorded on the optical disc. Further, the dummy pit row group is formed in a concentric circle shape or a spiral shape at a predetermined pitch, or even if dummy pits are arranged on parallel straight lines at a predetermined pitch as long as they form a plane diffraction grating, for example, the Qinghai wave. It may be formed by a mosaic arrangement such as. Further, instead of the dummy pit group, a phase hologram may be formed in which the intensity distribution of the interference fringes between the reference light and the predetermined recording light such as a pattern is recorded as fine irregularities on the surface of the reflecting layer,
Rainbow holograms are particularly preferable.

As the disc accompanying information carried by the pattern display area P, the type of the optical disc such as LD, CD, DVD, CD, MO and the information recording area such as music information, graphic information, patent information, compression format information, etc. Examples include the type of recorded information, its index information, and content information such as title information. Further, the pattern display area P may be provided with a visually recognizable title, an optical pattern of characters, symbols, pictures for identification or the like, or a pattern readable by an optical device such as a barcode. The optical disk of the embodiment is specifically a DVD, for example, a substrate having a diameter of 12 cm and a thickness of 0.6 mm, 500 to 1500.
It can be formed as a double-sided optical disc including an angstrom-thick reflective film, a protective film having a thickness of 5 to 20 μm, and an adhesive layer having a thickness of several tens of μm. (Method of Manufacturing Optical Disc Master) Next, a method of manufacturing the optical disc master of the present invention will be described. The manufacturing method of the present invention will be briefly described. For example, a group of steps for forming a preliminary optical disc master having a background portion pattern (diffraction grating area) for performing rainbow color display or hologram display by reflected and diffracted light from a diffraction grating of a dummy pit. , A group of steps for individually forming the pattern portion of the main subject on the background. FIG. 3 (first embodiment) and FIG. 4 (second embodiment) show a method of manufacturing an optical disk master including a post-process of individually forming a main display pattern area by using a so-called laser marker method and etching method. (Formation of master disk for preliminary optical disc) First, the glass substrate on which the positive type resist layer is uniformly formed on the main surface is rotated, and a laser beam spot that blinks according to a dummy signal is moved in the radial direction of the substrate to irradiate the resist. Dummy spot row latent images are formed in a spiral or concentric pattern on the layer. Next, the exposed resist base is developed to form a resist pit row, which is dried and post-baked to obtain a master disk. Next, a metal conductive film is uniformly laminated on the resist pit row of the master disk. This is immersed in an electroforming tank to grow a metal film to form a stamper, and the stamper is separated from the glass substrate to create a master stamper in which only the pit rows (diffraction grating area) for the iridescent display background are formed. To do. A large number of spare stampers 61 for molding are created from this master stamper through an electroforming process (FIG. 3).
a).

(Dummy Pit Removal Process by Laser Marker Method) Next, as shown in FIG. 3b, a laser beam 64 is prepared in advance according to a main display pattern of characters, symbols, pictures, etc., which is a main subject matter in the first embodiment. The dummy pit forming region of the stamper 61 is selectively irradiated continuously or by scanning to melt predetermined dummy pits and crush them to form shallow recesses. As shown in FIG. 3c, the main display pattern is set in the background of the dummy pit row. Draw directly on the optical disc master 6
Form 2 Here, the main display pattern portion is a diffuse reflection portion where reflected diffracted light is not generated.

According to the first embodiment, a variety of main display patterns are provided from a stamper for a common background of an optical disk master carrying a background dummy pit row and a portion of the main display pattern surrounded by the dummy pit row. The optical disk master can be formed in a small number of steps. (Step of Removing Dummy Pits by Etching Method) Further, as a method of manufacturing an optical disk master according to the second embodiment using the etching method, first, as in the first embodiment,
A spare stamper, that is, a spare optical disk master 61, whose entire surface is only a rainbow display background shown in FIG. 4a is prepared.

Next, as shown in FIG. 4B, a main display pattern made of an ultraviolet curable resin having openings for main display patterns such as characters, symbols and pictures, which are main materials, is formed on the dummy pit row of the spare stamper 61. The main display pattern mask 71 is formed by applying by screen printing and curing the ultraviolet curable resin by ultraviolet irradiation. Next, as shown in FIG. 4C, the dummy pits exposed from the opening of the main display pattern mask 71 and the periphery thereof are melted by a predetermined etchant to crush these dummy pits to form shallow flat recesses. Therefore, the main display pattern portion becomes the mirror surface portion. By this etching method, the stamper 62 that carries the main display pattern is obtained.

Next, as shown in FIG. 4D, the main display pattern mask 71 is removed from the stamper 62 with a predetermined solvent to form an optical disc master 62. Also according to the second embodiment, an optical disk master carrying a background dummy pit row and a portion without a dummy pit row of a main display pattern surrounded by the same has a common stamper for the background and an optical disk of various main display patterns. A master can be formed. (Manufacturing Method of Optical Disc Master Forming Other Diffraction Grating Areas) In the above embodiment, in the obtained double-sided optical disc, the main display pattern portion is the mirror surface portion in the dummy pit area where the entire background is rainbow-colored. Or, you can get pit art that is a diffuse reflection part where reflected diffracted light does not occur
Further, in the following third embodiment, an optical disc master with a hologram as a background is prepared in place of a diffraction grating of dummy pits for rainbow color display in a display pattern divided into two as a main subject and a background. .

First, as shown in FIG. 5a, a glass substrate 111 having a positive or negative photoresist layer 112 uniformly formed on its main surface is prepared. Next, as shown in FIG. 5b, a holographic device exposes a predetermined background pattern to light to form a background pattern latent image. Next, as shown in FIG. 5c, the exposed resist substrate is developed, dried and post-baked to obtain a master disk having fine irregularities corresponding to interference fringes on the surface of the resist layer 112.

Next, as shown in FIG. 5d, a metal conductive film 113 is uniformly laminated on the fine irregularities of the master disk. Next, as shown in FIG. 5e, this is immersed in an electroforming tank to grow a metal film 113 and form a preliminary stamper 114. Next, as shown in FIG.
Is separated from the glass substrate to prepare a preliminary stamper whose surface serves as a hologram pattern 115 having a background pattern.

After that, a part of the hologram mold 115 of the preliminary stamper 114 is processed by the laser marker method or the etching method shown in FIG. 3 or 4 of the first or second embodiment, for example, characters, symbols, pictures, etc., which are main subjects. According to the main display pattern of the hologram type 1 as shown in FIG. 5g.
It is possible to form the pit art optical disc master 116 in which the main display pattern portion P with 15 as a background is a mirror surface portion or an irregular reflection portion in which reflected diffracted light does not occur.

[0029]

As described above, according to the present invention, in the method of manufacturing an optical disc, the pattern to be displayed is divided into, for example, a main material and a background, and as a background, a rainbow caused by the diffracted light reflected from the diffraction grating is used. Since it is composed of a preliminary stamper forming step of forming a background portion pattern by using a common color display or hologram display and a step by a laser marker method or an etching method of individually forming a pattern portion of a main subject, the conventional stamper is used. There is no need to laser-cut each pattern. Further, the spare stampers of the background display patterns can be stored as a family, the combinations of them can be abundant, and many stampers can be easily manufactured. Furthermore, it becomes possible to display a sufficiently large pattern even on a small-sized high-density optical disk such as a DVD.

[Brief description of drawings]

FIG. 1 is a schematic partial cross-sectional view of an optical disc according to an embodiment of the present invention.

FIG. 2 is a perspective view of an optical disc according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view of a substrate in a method of manufacturing an optical disc master according to the present invention.

FIG. 4 is a cross-sectional view of a substrate in a method for manufacturing an optical disc master according to the present invention.

FIG. 5 is a cross-sectional view of a substrate in a method for manufacturing an optical disc master according to the present invention.

[Explanation of symbols for main parts]

 2, 8 Substrate 3, 7 Reflective layer 4, 6 Protective film 5 Adhesive layer 9 Dummy pit 10 Information pit 11 Dummy disk part 12 Information recording disk part P Pattern display area 54, 64 Laser beam 42 Optical disk 61, 114 Spare stamper 62 , 116 stamper 71 mask 112 photoresist layer 111 glass substrate 113 metal conductive film 115 hologram type

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yu Murakami 2680 Nishi Hanawa, Tatomi-cho, Nakakoma-gun, Yamanashi Prefecture Pioneer Video Co., Ltd.

Claims (4)

[Claims] 1. One of the recording surfaces has a recording track formed of concentric circles or spirals composed of a pit row for carrying an information signal, and the other of the recording surfaces has a diffraction grating region for generating diffracted light by incident light. A method of manufacturing an optical disc master for a reflective optical disc having a pit row on both recording surfaces, which has a display pattern area that does not generate diffracted light by the incident light formed in the diffraction grating area. And a step of forming a spare optical disk master having the diffraction grating area on a main surface, and a step of removing only a portion of the spare optical disk master corresponding to the display pattern area in the diffraction grating area. A method for manufacturing an optical disc master, which is characterized by the above. 2. The method of manufacturing an optical disc master according to claim 1, wherein the diffraction grating region is a dummy pit row or a pre-groove formed in a spiral shape or a concentric shape at a predetermined pitch. 3. The method of manufacturing an optical disk master according to claim 1, wherein the diffraction grating region is a dummy pit row or a pre-groove formed in parallel straight lines at a predetermined pitch. 4. The method of manufacturing an optical disk master according to claim 1, wherein the diffraction grating region is a hologram.