KR19990081766A - Optical recording medium and its manufacturing method - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording medium in which various kinds of information such as image information are optically recorded and / or reproduced, and a manufacturing method thereof.

According to the present invention, a light transmitting layer on which a light beam is incident and a substrate layer thicker than the light transmitting layer are formed to form a recording surface on the substrate layer, and then the light transmitting layer and the substrate layer are bonded.

According to the present invention, a thin light transmitting layer is formed to improve the tilt tolerance angle according to the high density trend, and a pit pattern is formed on a thick protective layer so that the transfer of the pit pattern can be easily made.

Description

Optical Recording Media And Methods OF Fabricating The Same

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to an optical recording medium and a method of manufacturing the same, and more particularly, to an optical recording medium and a method of manufacturing the same, in which various kinds of information such as image information are optically recorded and / or reproduced.

Background Art [0002] Optical recording media such as DVD, which have a higher recording density than CD, have already been generalized. In addition, optical recording media have been developed in a large capacity and high density trend until the MOD (Magneto-Optical Disk), which records information using magnetic field modulation recording method and irradiates light on the recording surface and reproduces the information. It is becoming. As can be seen from FIG. 1, these optical recording media include a light transmissive layer 2, a reflective film 4 formed on the light transmissive layer 2, and a protective film 6 formed on the reflective film 4. Is done. In the light transmissive layer 2, the reflection film 4 side becomes a recording surface on which information is recorded by forming a pit or guide groove. On the other hand, in the manufacturing method, a DVD manufactures a stamper by mastering, attaches the stamper to a molding machine, and injects a substrate material (Polycarbonate, Glass, etc.) into the molding machine and press-forms the recording surface. The formed light transmitting layer 2 is provided. Next, aluminum (Al) is deposited on the light transmitting layer 2 by the sputtering method to form the reflective film 4, and the protective film 6 is formed on the reflective film 4 by the spin coating method. You will be formed. DVDs completed by these processes are subjected to light reflection and optical quality inspection.

On the other hand, as the thickness of the substrate 2 (for example, the thickness of the CD substrate is 1.2 mm and the thickness of the DVD and MOD substrate is 0.6 mm) becomes thinner, the deformation caused by stress, heat, etc. becomes more severe and the surface uniformity is inferior. do. On the other hand, as the thickness of the light transmitting layer 2 becomes thicker, it becomes more sensitive to skew, the nature of the laser beam focused on the pit, and aberration (particularly coma aberration). When the disk skew is constant, the thinner the light transmitting layer 2 becomes, the smaller the aberration is in the spot. As the density of optical recording media increases, the pits formed in the light transmitting layer are gradually reduced in size (width, length). The thin trend of pit size means that the pit transfer requires very high precision in injection molding. Increasing the density of optical recording media has resulted in a decrease in pit size, densification of track pitch, and increase in numerical aperture (NA). The trend of densification can be achieved only when the aberration amount is largely generated due to the tilt according to the degree of tilt of the objective lens or the degree of tilt of the spindle motor, and the reproduction signal is degraded accordingly. Accordingly, it is common to recognize that the light transmitting layer should use an ideal material that is very flat and not deformed, but this is practically impossible. In order to solve these problems, it is disclosed in Japanese Patent Laid-Open No. 8-235638 to make the thickness of the light transmitting layer 0.5 mm or less. According to the proposed method of manufacturing the optical recording medium, the pit is transferred to a thick support layer by spin coating the light transmitting layer onto a relatively thick support layer and forming a thin light transmitting layer. However, since the former method is spin coating, an extremely thin light transmitting layer is not applied with a uniform thickness, and the latter method has a problem in that the pit pattern is not accurately made because the pit is transferred to a thin substrate. Therefore, there is a demand for an optical recording medium and a method of manufacturing the same, in which the light transmission layer is thin and the pit transfer is well performed.

Accordingly, it is an object of the present invention to provide an optical recording medium and a method for manufacturing the same, which are suitable for high density.

1 is a longitudinal sectional view showing the structure of a conventional optical recording medium.

Fig. 2 is a longitudinal sectional view showing the optical recording medium according to the first embodiment of the present invention.

FIG. 3 is a process chart showing step by step the manufacturing method of the optical recording medium shown in FIG. 2; FIG.

Fig. 4 is a longitudinal sectional view showing the optical recording medium according to the second embodiment of the present invention.

Fig. 5 is a longitudinal sectional view showing the optical recording medium according to the third embodiment of the present invention.

FIG. 6 is a process chart showing step by step the manufacturing method of the optical recording medium shown in FIG. 5; FIG.

FIG. 7 is a process chart showing step by step another manufacturing method of the optical recording medium shown in FIG.

FIG. 8 is a process chart showing step by step another manufacturing method of the optical recording medium shown in FIG.

<Description of the symbols for the main parts of the drawings>

2,10: Light transmitting layer 4,12,30,30 ': Reflective film

8: objective lens 6, 14, 28: protective film (substrate layer)

16: disc 18,32,36,40 stamper

20,22,24,26: cover layer 34,38,42: molding machine

In order to achieve the above object, the optical recording medium of the present invention includes a light transmitting layer made by injection molding, and a substrate layer formed thicker than the light transmitting layer to form a recording surface and bonded to the light transmitting layer.

An optical recording medium of the present invention includes a light transmitting layer having a thickness of t1, and a substrate layer molded to a thickness of t2 larger than t1 to form a recording surface and bonded to the light transmitting layer.

The optical recording medium of the present invention is molded into a first cover layer having a thickness of t1, a second cover layer having a thickness of t2, and a thickness of t3 larger than t1 and t2 to form a recording surface, and the first and second covers. And a substrate layer to which the layers are symmetrically bonded.

The method of manufacturing an optical recording medium according to the present invention comprises the steps of providing a light transmitting layer through which a light beam is incident, forming a recording layer on the substrate layer by providing a substrate layer thicker than the light transmitting layer, and a light transmitting layer and a substrate layer. Bonding the step.

A method of manufacturing an optical recording medium according to the present invention comprises the steps of providing a light transmitting layer having a thickness of t1, preparing a substrate layer having a recording surface formed with a thickness of t2 greater than t1, and transmitting the substrate layer to light transmission. Bonding to the layer.

The method of manufacturing an optical recording medium according to the present invention comprises the steps of providing a first cover layer having a thickness of t1, providing a second cover layer having a thickness of t2, and having a thickness of t3 greater than t1 and t2. Providing a substrate layer to form a recording surface on the substrate layer, and symmetrically bonding the first and second cover layers to the substrate layer.

A method of manufacturing an optical recording medium according to the present invention comprises the steps of: preparing a first cover layer formed with a thickness of t1 and having a first recording surface and a first reflective film sequentially formed; Providing a second cover layer in which the second reflecting film is sequentially formed; and preparing a substrate layer having a thickness of t3 greater than t1 and t2, and bonding the first and second cover layers to the substrate layer. .

Other objects and advantages of the present invention in addition to the above object will be apparent from the description of the embodiments with reference to the accompanying drawings.

Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 2 to 8.

2 shows an optical recording medium according to the first embodiment of the present invention.

In the configuration of FIG. 2, the optical recording medium of the present invention includes a thin light transmitting layer 10, a substrate layer 14 formed thicker than the light transmitting layer 10, and having a recording surface, and a reflective film 12 formed on the recording surface. ).

The light beam is incident on the light transmitting layer 10 from the objective lens 8. In the substrate layer 14, a recording surface made of a pit pattern or a guide is formed. A reflective film 12 is formed on the recording surface on which the pit pattern is formed in the substrate layer 14. The substrate layer 14 serves as a protective film for preventing the deterioration of the reflective film 12. When the thickness of the light transmitting layer 10 is t1 and the thickness of the substrate layer 14 is t2, t2> t1 is set. The light transmitting layer 10 may be formed to a thin thickness to secure a tilt margin according to the high density. The light transmissive layer 10 is molded to a thin thickness, but unlike the prior art, since the recording surface is not formed, injection molding is facilitated. Since the substrate layer 14 is formed relatively thick, small-size pits or guides can be precisely formed according to the high density trend.

3A to 3D are process diagrams showing step by step the manufacturing method of the optical recording medium shown in FIG. First, the disk 16 is prepared by the mastering process in step (A). The disk 16 is formed by forming a photoresist film on a substrate and then exposing the laser light to the photoresist film with an exposure pulse corresponding to a desired pit shape to form a pit pattern and develop it. In step (B), the stamper 18 is fabricated by inverting and transferring the pit pattern formed on the disc 16. In step (C), the stamper 18 is attached to the molding machine, the substrate material (eg, Polycarbonate, Glass, etc.) is injected into the molding machine, and then the substrate layer 14 is replicated by solidification. At this time, a recording surface formed of a pit pattern is formed on the substrate layer 14. In the step (D), the reflective film 12 is formed by forming a total reflection material (for example, a metal thin film such as Al) on the recording surface in the substrate layer 14 by the sputtering method. Then, in step (E), a light transmitting layer 10 is prepared by injection molding a substrate material (eg, polycarbonate, glass, etc.), and then the light transmitting layer 10 faces the recording surface of the substrate layer 14. The light-transmitting layer 10 and the substrate layer 14 are bonded to each other by irradiation with ultraviolet (UV) light. Then, in step (F), the optical recording medium shown in FIG. 2 is completed. Here, for compatibility with optical recording media such as CD and DVD, the total thickness is set to 1.2 mm in the same manner as these optical recording media, and the light transmitting layer 10 and the substrate layer 14 are separated on the basis of the relationship t2> t1. You can set the thickness. For example, setting t1 = 0.3 mm and t2 = 0.9 mm (t1 + t2 = 1.2 mm) makes it compatible with optical recording media such as CD and DVD.

4 is a longitudinal sectional view of an optical recording medium according to a second embodiment of the present invention.

In the arrangements of FIGS. 4A and 4B, the optical recording medium of the present invention includes the first and second cover layers 20 and 22 which are symmetrically bonded above and below the substrate layer 24 on which the recording surface is formed. Equipped. The first cover layer 20 becomes a light transmitting layer through which the light beam is incident from the objective lens 8. The substrate layer 24 serves as a protective film. A recording surface is formed on the substrate layer 24, and a reflective film 12 is formed on the recording surface. Since the recording surface is formed, the substrate layer 24 is formed relatively thick so that the transferability of the pit pattern is good. Since the first cover layer 20 is molded to a thin thickness, it is possible to secure the tilt margin according to the high density. The second cover layer 22 is bonded to the third substrate layer 24 symmetrically with the first cover layer 20 with the third substrate layer 24 therebetween, so that the bending deformation according to the change in the driving environment such as humidity can be achieved. It serves to prevent the back. Here, the second cover layer 22 is molded to the same thickness as the first cover layer 20 in consideration of symmetry with the first cover layer 20. The thickness of each layer has a relationship of t3> t1 (t2) when the thicknesses of the first and second cover layers 20 are t1 and t2 and the thickness of the substrate layer 24 is t3. In consideration of compatibility with optical recording media such as CD and DVD, when the thickness is set to t1 = t2 = 0.3 mm and t3 = 0.6 mm, the total thickness is 1.2 mm, which makes it compatible with optical recording media such as CD and DVD. .

5 is a longitudinal sectional view of an optical recording medium according to a third embodiment of the present invention.

In the configuration of FIGS. 5A and 5B, the optical recording medium of the present invention is symmetrical on both the substrate layer 28 on which the upper and lower recording surfaces are formed, and on both the upper and lower surfaces of the substrate layer 28. The first and second cover layers 24 and 26 are bonded to each other. The first and second cover layers 24 and 26 become light transmitting layers through which light beams are incident from the objective lens 8. In the substrate layer 28, the pit pattern is reversely transferred on both upper and lower surfaces to form a recording surface, and reflective films 30 and 30 'are formed on the recording surfaces. Therefore, the substrate layer 28 becomes a protective film for preventing the deterioration of the reflective films 30 and 30 '. The optical recording medium having such a configuration has a double-sided recording surface, and the first and second cover layers 24 and 26 are symmetrically bonded to the substrate layer 24 to prevent bending deformation and the like. Here, when the thicknesses of the first and second cover layers 24 are t1 and t2, respectively, and the thickness of the substrate layer 28 is t3, t3> t1 (t2) is set, t1 = t2 = 0.3 mm, When t3 = 0.6 mm, the overall thickness is 1.2 mm, which makes it compatible with optical recording media such as CD and DVD.

The optical recording media shown in FIGS. 4 and 5 are produced by a similar manufacturing method.

6A to 6H are process diagrams showing in steps a manufacturing method of an optical recording medium according to a third embodiment of the present invention.

Referring to FIG. 6, in step (A), a master is prepared by a mastering process, and the stamper 32 is manufactured by inverting and transferring the pit pattern formed on the master. The stamper 32 is mounted on the upper and lower sides of the molding machine 34, and then molten substrate material (e.g., polycarbonate, glass, etc.) is injected into the molding machine 34. In step (B), the molding machine 34 is compressed to form recording surfaces reversely transferred by the stampers 32 on both the upper and lower surfaces of the substrate layer 28. In the step (C), a total reflection material (for example, a metal material such as Al) is formed on the first recording surface of the substrate layer 28 as a reflective film material by sputtering or the like to form the first reflective film 30. In step (D), the UV bond material is applied on the first reflective film 30 by the spin coating method. The UV bond material is irradiated with UV light and cured, and the first cover layer 24 is placed thereon. In step (E), the first cover layer 24 is pressed onto the UV bond material to bond the first cover layer 24 to the substrate layer 28. In the step (F), a total reflection material (for example, a metal material such as Al) is formed on the second recording surface of the substrate layer 28 by sputtering or the like to form the second reflection film 30 '. In the step (G), the UV bond material is applied onto the second reflective film 30 'by spin coating, and the UV bond material is irradiated with ultraviolet rays to cure. Then, the second cover layer 26 is placed on the UV bond material so as to face each other. In step (H), the second cover layer 26 is pressed onto the UV bond material to bond the second cover layer 26 to the substrate layer 28. The finished optical recording medium undergoes a good quality discrimination process by reflectance and optical quality inspection. On the other hand, in the case of the optical recording medium having the recording surface of the cross section shown in Fig. 4, in the steps (A) and (B), only one stamper 32 is attached to the molding machine 34 so that the cross-sectional recording surface is formed. After the reflective film 12 is formed on the recording surface in step (C), the first and second cover layers 20 and 22 are symmetrically bonded on both the upper and lower surfaces of the substrate layer 12.

Alternatively, the first and second reflective layers 30 and 30 'may be formed in one process, and the first and second cover layers 24 and 26 may be separately bonded.

7A to 7G are process diagrams showing step by step another manufacturing method of the optical recording medium according to the third embodiment of the present invention.

Referring to FIG. 7, in step (A), a disk is prepared by a mastering process, and the stampers 32 are manufactured by inverting and transferring the pit pattern formed on the disk. The stampers 32 are mounted on the upper and lower sides of the molding machine 34, and then the molten substrate material is injected into the molding machine 34. In step (B), the molding machine 34 is compressed to form recording surfaces reversely transferred by the stampers 32 on both the upper and lower surfaces of the substrate layer 28. In the step (C), a total reflection material (for example, a metal material such as Al) is formed on the first and second recording surfaces of the substrate layer 28 as a reflective film material by sputtering or the like, so that the first and second reflective films 30 are formed. 30 ') is formed. In step (D), the UV bond material is applied on the first reflective film 30 by the spin coating method. The UV bond material is irradiated with UV light and cured, and the first cover layer 24 is placed thereon. In step (E), the first cover layer 24 is pressed onto the UV bond material to bond the first cover layer 24 to the substrate layer 28. In step (F), the UV bond material is applied onto the second reflective film by a spin coating method. The UV bond material is irradiated with UV light and cured, and the second cover layer 26 is placed thereon. In step (G), the second cover layer 24 is pressed onto the UV bond material to bond the second cover layer 26 to the substrate layer 28. The finished optical recording medium undergoes a good quality discrimination process by reflectance and optical quality inspection.

8A to 8E are process diagrams showing step by step another manufacturing method of the optical recording medium according to the third embodiment of the present invention.

Referring to FIG. 8, in step (A), the masters are provided with disks corresponding to the first and second recording surfaces, and the stampers 36 and 40 are made by inverting and transferring the pit patterns formed on the respective disks. Will be produced. Respective stampers 36 and 40 are mounted to first and second molding machines 38 and 42. The molten substrate material is injected into the first and second molding machines 38 and 42. In step (B), each of the molding machines 38 and 42 is compressed to provide first and second cover layers 29 having first and second recording surfaces which are reversely transferred by the stampers 32. In the step (C), a total reflection material (for example, a metal material such as Al) is formed on the first and second recording surfaces of the first and second cover layers 24 and 26 as a reflective film material by sputtering or the like, respectively. First and second reflective films 30 and 30 'are formed. In steps (D) and (E), after the UV bond material is applied by the spin coating method to form the substrate layer 28 on the first and second reflective films 30 and 30 ', respectively, the ultraviolet light is applied to the UV bond material. Irradiated to harden. The first and second reflective films 30 and 30 'are opposite to each other, and then the first and second cover layers 24 and 26 are bonded to the substrate layer 28. Here, the thickness of the substrate layer 28 is designed to be 0.6mm. Thus, the substrate layer 28 can be effectively applied to the embodiment of Fig. 8 in the case where the recording surface formation in a set of molding machines is impossible with two stampers.

On the other hand, in the case of manufacturing a disc for recording once (WORM type) or a rewritable in the method of manufacturing an optical recording medium according to the present invention, instead of forming a reflective film, an organic dye polymer (dye polymer) applied to CD-R or the like is applied. Or a phase change recording material or magneto-optical recording material layer is deposited on the pit pattern of the third substrate layer 28.

As described above, the optical recording medium of the present invention and its manufacturing method form a thin light transmitting layer to improve the tilt tolerance angle according to the high density trend, and the pit pattern is formed on a thick protective layer to facilitate the transfer of the pit pattern. This makes it suitable for high density recording / reproducing. Furthermore, the optical recording medium and the manufacturing method thereof of the present invention can prevent bending deformation by symmetrically bonding the substrates.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

Claims (32)

A light transmitting layer made by injection molding, And a substrate layer formed to be thicker than the light transmitting layer to form a recording surface and bonded to the light transmitting layer. The method of claim 1, And a reflective film formed between the light transmitting layer and the substrate layer. a light transmitting layer having a thickness of t1, And a substrate layer formed to a thickness of t2 greater than t1 to form a recording surface and to be bonded to the light transmitting layer. The method of claim 3, wherein And t1 is 0.5 mm or less. The method of claim 3, wherein And t2 is 0.6 mm or more. The method according to claim 4 or 5, And t1 = 1.2 mm-t2. The method of claim 3, wherein And a reflective film formed between the light transmitting layer and the substrate layer. The method of claim 3, wherein And a recording material layer formed between the light transmitting layer and the substrate layer. The method of claim 8, And the recording material layer is any one of an organic dye polymer, a phase change recording material and a magneto-optical recording material. The method according to claim 3 or 7, And the substrate layer is a protective layer for preventing deterioration of the reflective film. a first cover layer having a thickness of t1, a second cover layer having a thickness of t2, And a substrate layer formed with a thickness of t3 greater than t1 and t2 to form a recording surface, and wherein the first and second cover layers are symmetrically bonded together. The method of claim 11, And a recording surface is formed on the first and / or second cover layer. The method of claim 11, And t1 and t2 are the same thickness. The method of claim 11, And the recording surface is formed in a cross section in the substrate layer. The method of claim 11, And the recording surface is formed on both sides of the substrate layer. The method of claim 11, T3 = 1.2mm-2t1, And t1 and t2 are 0.3 mm or less. The method of claim 11, Between the first cover layer and the substrate layer, And first and second reflective films formed between the second cover layer and the substrate layer. The method of claim 11, Between the first cover layer and the substrate layer, And a recording material layer formed between the second cover layer and the substrate layer. Providing a light transmitting layer through which the light beam is incident; Forming a recording surface on the substrate layer by providing a substrate layer thicker than the light transmitting layer; And bonding the light transmitting layer and the substrate layer to each other. The method of claim 19, Forming the recording surface comprises the steps of preparing a master disk on which a pit pattern is formed; Manufacturing a stamper by inverting and transferring the pit pattern; And attaching the stamper to a molding machine, followed by compression molding by injecting a substrate layer material into the molding machine at a high temperature. The method of claim 19, And forming a reflective film on the substrate layer. The method of claim 19, Forming the recording surface comprises the steps of preparing a master disk on which a pit pattern is formed; Forming a stamper by inverting and transferring the pit pattern; Attaching the stamper to a molding machine and then compressing the molding by hot injection of a substrate layer material into the molding machine; And forming a recording material layer on the substrate layer. The method of claim 22, And the recording material layer is any one of an organic dye polymer, a phase change recording material and a magneto-optical recording material. providing a light transmitting layer having a thickness of t1, Providing a substrate layer having a recording surface with a thickness of t2 greater than t1; Bonding the substrate layer to the light transmitting layer. providing a first cover layer having a thickness of t1; providing a second cover layer having a thickness of t2; Forming a recording surface on the substrate layer by providing a substrate layer having a thickness of t3 greater than t1 and t2; And symmetrically bonding the first and second cover layers to the substrate layer. The method of claim 25, The forming of the recording surface may include forming a stamper using a disc; Attaching the stamper to a molding machine and injecting the dissolved substrate material into the molding machine; Forming the substrate layer by compressing the molding machine; And forming a reflective film on the substrate layer. The method of claim 25, The forming of the recording surface may include forming a stamper using a disc; Attaching the stamper to a molding machine and injecting the dissolved substrate material into the molding machine; Forming the substrate layer by compressing the molding machine; And forming a recording material layer on the substrate layer. The method of claim 25, And the recording surface is formed on any one of the upper and lower surfaces of the substrate layer. The method of claim 25, And the recording surface is formed on both sides of the substrate layer. The method of claim 25 or 29, The forming of the recording surface may include forming first and second stampers using a disc; Forming the substrate layer having the first and second recording surfaces by attaching the first and second stampers to a molding machine, injecting the substrate material at a high temperature, and then compression molding; Forming a first reflective film on the first recording surface; And forming a second reflective film on the second recording surface. The method of claim 25 or 29, The forming of the recording surface may include forming first and second stampers using a disc; Forming the substrate layer having the first and second recording surfaces by attaching the first and second stampers to a molding machine, injecting the substrate material at a high temperature, and then compression molding; And forming first and second reflective films on the first and second recording surfaces. providing a first cover layer formed to a thickness of t1 and having a first recording surface, a first reflective film, and a first protective film sequentially formed; providing a second cover layer formed to a thickness of t2 and having a second recording surface, a second reflective film and a second protective film sequentially formed; Bonding the first and second cover layers to the substrate layer such that the thicknesses of the first and second passivation films are t3 greater than t1 and t2.