KR100618998B1 - High density optical disk - Google Patents

Abstract

Disclosed is a high-density optical disc having a structure in which approximately 15 gigabytes or more of information can be recorded on each information recording surface, and a tilt margin can be secured.

The disclosed high-density optical disk has a three-piece double-sided two-layer structure, a four-piece double-sided two-layer structure, a three-piece double-sided two-layer structure, a three-piece double-sided two-layer structure, three-piece one side and one side the other side. Is characterized in that the two-layered structure, two-layered two-layered structure of three pieces. This high-density optical disc is characterized in that each of D ₁ and D ₂ satisfies the following conditional expressions 1 and 2 when the thickness from the incident surface of the information substrate to the information recording surface is D ₁ or D ₂ .

<Condition 1>

<Condition 2>

Description

High density optical disk

1 is a schematic cross-sectional view showing a conventional double-sided one-layered optical disk.

FIG. 2 is a schematic cross-sectional view showing a high density optical disc having a two-piece double-layered structure of three pieces according to a first embodiment of the present invention; FIG.

FIG. 3 is a schematic cross-sectional view showing a high density optical disk having a four-piece double-sided double layer structure according to a second embodiment of the present invention; FIG.

Fig. 4 is a schematic cross sectional view showing a high density optical disc having a two-piece double-sided two-layer structure according to a third embodiment of the present invention.

Fig. 5 is a schematic cross sectional view showing a high density optical disc having a two-piece double-sided structure in accordance with a fourth embodiment of the present invention.

FIG. 6 is a schematic cross-sectional view showing a high density optical disc having a one-layer structure on one side and a two-layer structure on the other side according to a fifth embodiment of the present invention; FIG.

FIG. 7 is a schematic cross-sectional view showing a high density optical disc having a three-piece double sided structure according to a sixth embodiment of the present invention; FIG.

<Description of Symbols for Main Parts of Drawings>

111 The first information board 111a ... the first entrance plane 111b ... the first recording plane

113 The first reflective layer 121 The second information substrate 121a The second entrance surface                 

121b ... 2nd recording surface 123 ... 2nd reflective layer 131 ... 3rd information board

131a ... 3rd recording surface 131b ... 4th recording surface 133 ... 3rd reflective layer

135 The fourth reflective layer 141, 143 Spacer

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high density optical disc, and more particularly, to a high density optical disc having an improved structure so that approximately 15 gigabytes or more of information can be recorded on each information recording surface.

In general, an optical disc is widely used as an information recording medium of an optical pickup apparatus for recording / reproducing information in a non-contact manner, and is classified into a compact disc (CD) and a digital multifunction disc (DVD) according to the information recording capacity.

Each of the CD and DVD is standardized as shown in Table 1 in consideration of mutual compatibility and information recording density.

CD DVD Disc diameter (mm) 120 120 Disk thickness (mm) 1.2 1.2 Information board thickness (mm) 1.2 0.6 Track Pitch (μm) 1.6 0.74 Minimum Feet Size (μm) 0.83 0.4 Wavelength (nm) 780 635/650 Single Board Capacity (GB) 0.65 4.7

Here, the disc diameter and the disc thickness represent the external appearance of the CD and the DVD, and are set to the same size in consideration of the internal space of the compatible disc player and the specifications of the disc tray for loading / unloading the disc.

On the other hand, in order to increase the capacity of the information recording capacity of the DVD to about 4.7 GB, the DVD has standardized different wavelengths, track pitches (gaps between tracks and tracks), and minimum pit sizes. That is, by shortening the light emitted from the light source of the optical pickup device, for example, a semiconductor laser, into the 635/650 nm wavelength region, the size of the light spot formed on the disk can be reduced, so that the track pitch and the minimum pit size can be reduced.

In addition, when the CD was initially developed, it was difficult to produce a disc making thickness of 1.2 mm or less, so that the disc thickness was 1.2 mm to minimize degradation of the playback signal due to foreign matter on the substrate surface.

On the other hand, when DVDs are standardized to the same thickness as the substrate thickness of the CD, errors in the disc recording / reproducing are high because the tolerance of the disc tilt due to the densification becomes small. In view of this, the board thickness of the DVD has been standardized to 0.6 mm. Here, the DVD records signals digitally, so that signal degradation due to contamination of the disk surface can be processed in a circuit.

DVDs having the above-described standards can be divided into single-sided one-layer structure, double-sided one-layer structure, single-sided two-layer structure and double-sided two-layer structure in consideration of information recording capacity.

Referring to FIG. 1, a DVD having a double-sided one-layer structure includes a first and second information substrates 11 and 21 having a thickness of 0.6 mm, and recording surfaces 11a of each of the first and second information substrates 11 and 21. And a bonding layer 15 provided between the first and second reflection layers 13 and 23 coated on the shell 21a and the first and second reflection layers 13 and 23. The optical disc of the double-sided single layer structure thus constructed has an information recording capacity of about 9.4 GB, which is twice the information capacity of the optical disc having the single-sided single layer structure.

The DVD having the structure as described above has the advantage that the information capacity is larger than that of the conventional CD while maintaining the total thickness of the 0.6 mm thick information substrate.

On the other hand, when the thickness of the information substrate is normalized to 0.6 mm as described above, a short wavelength optical pickup of about blue wavelength region (approximately 410 nm) is employed and 15 gigabyte per side is adopted. In the recording / reproducing level of ultra high density information, the allowable range of the disc tilt which does not affect the recording / reproducing is drastically reduced. This is due to the coma aberration allowance according to the inclination of the disk being proportional to the wavelength, inversely proportional to the third power of the objective lens opening, and inversely proportional to the disk thickness.

Therefore, even when the optical pickup apparatus having a light source and an objective lens suitable for optical ultra-high density information recording is employed, the disc tilt allowance is reduced when the recording medium is employed in the DVD having the above-described structure. byte There is a problem that it is impossible to record / reproduce ultra-high density information at a level.

Accordingly, an object of the present invention is to provide a high-density optical disc of a standard having the same size as that of a DVD and a CD and having an information capacity of 15 gigabytes or more per side.

In order to achieve the above object, the high-density optical disc according to the present invention comprises: a first information substrate having a first entrance surface on which recording / reproducing light is incident and a first recording surface on which an information signal is recorded; A first reflection layer formed on the first recording surface and reflecting a part of the incident light; A second information substrate having a second entrance surface on which recording / reproducing light is incident, and a second recording surface on which an information signal is recorded; A second reflection layer formed on the second recording surface and reflecting a part of the incident light; A third recording surface formed between the first information substrate and the second information substrate, the third recording surface having the information signal recorded / reproduced by the light transmitted through the first reflective layer, and the information signal by the light transmitted through the second reflective layer; A third information substrate having a fourth recording surface on which is recorded / reproduced; A third reflection layer formed on the third recording surface to reflect incident light; And a fourth reflection layer formed on the fourth recording surface to reflect incident light.

In addition, the high-density optical disk according to the present invention comprises: a first information substrate having a first entrance surface on which recording / reproducing light is incident, and a first recording surface on which an information signal is recorded; A first reflection layer formed on the first recording surface and reflecting a part of the incident light; A second information substrate having a second entrance surface on which recording / reproducing light is incident, and a second recording surface on which an information signal is recorded; A second reflection layer formed on the second recording surface and reflecting a part of the incident light; A third information substrate bonded to a first reflection layer of the first information substrate, the third information substrate having a third recording surface disposed opposite to the first recording surface and having an information signal recorded / reproduced by light transmitted through the first reflection layer; ; A third reflection layer formed on the third recording surface to reflect incident light; A fourth recording surface which is formed between the second information substrate and the third information substrate, and has a fourth recording surface which is disposed to face the second recording surface so that the information signal is recorded / reproduced by light transmitted through the second reflective layer. 4 information board; And a fourth reflection layer formed on the fourth recording surface to reflect incident light.

In addition, the high-density optical disk according to the present invention comprises: a first information substrate having a first entrance surface on which recording / reproducing light is incident, and a first recording surface on which an information signal is recorded; A first reflection layer formed on the first recording surface and reflecting a part of the incident light; A second information substrate having a second entrance surface on which recording / reproducing light is incident, and a second recording surface on which an information signal is recorded; A second reflection layer formed on the second recording surface and reflecting a part of the incident light; A third recording surface formed between the first information substrate and the second information substrate, the third recording surface having the information signal recorded / reproduced by the light transmitted through the first reflective layer, and the information signal by the light transmitted through the second reflective layer; A fourth information substrate having a fourth recording surface on which is recorded / reproduced; A third reflection layer formed on the third recording surface to reflect incident light; And a fourth reflection layer formed on the fourth recording surface to reflect incident light.

In addition, the high-density optical disk according to the present invention comprises: a first information substrate having an incident surface on which recording / reproducing light is incident and a first recording surface on which an information signal is recorded; A first reflection layer formed on the first recording surface and reflecting a part of the incident light; A second information substrate bonded to the first information substrate, the second information substrate having a second recording surface on which the information signal is recorded / reproduced by light transmitted through the first reflection layer; A second reflection layer formed on the second recording surface to reflect incident light; And a dummy substrate formed bonded to a rear surface of the second information substrate opposite to the second recording surface.

In addition, the high-density optical disk according to the present invention comprises: a first information substrate having a first entrance surface on which recording / reproducing light is incident, and a first recording surface on which an information signal is recorded; A first reflection layer formed on the first recording surface and reflecting a part of the incident light; A second information substrate having a second entrance surface on which recording / reproducing light is incident, and a second recording surface on which an information signal is recorded; A second reflection layer formed on the second recording surface to reflect incident light; A third information substrate formed between the first information substrate and the second information substrate, the third information substrate having a third recording surface on which information signals are recorded / reproduced by light transmitted through the first reflection layer; And a third reflection layer formed on the third recording surface to reflect incident light.

In addition, the high-density optical disk according to the present invention comprises: a first information substrate having a first entrance surface on which recording / reproducing light is incident, and a first recording surface on which an information signal is recorded; A first reflection layer formed on the first recording surface to reflect incident light; A second information substrate having a second entrance surface on which recording / reproducing light is incident, and a second recording surface on which an information signal is recorded; A second reflection layer formed on the second recording surface to reflect incident light; And a dummy substrate formed by bonding between the first reflection layer and the second reflection layer so that the entire thickness of the optical disc is maintained at a predetermined thickness.

을 만족하는 것이 바람직하다. 또한, 상기 제1기판 및 제2기판의 두께를 D₂ 이라 할 때, 두께 D₂은 하기의 조건식

을 만족하는 것이 바람직하다.In addition, an optical disk according to the present invention comprises: a first substrate having a first incident surface on which recording / reproducing light is incident; A second substrate having a second incident surface on which recording / reproducing light is incident; A first recording surface which is formed between the first substrate and the second substrate, the first recording surface on which an information signal is recorded / reproduced by light incident through the first incident surface, and information by light incident through the second incident surface; An information substrate having a second recording surface on which signals are recorded / reproduced; A first reflection layer formed on the first recording surface to reflect incident light; And a second reflection layer formed on the second recording surface to reflect incident light. When the thicknesses of the first substrate and the second substrate are D ₁ , the thickness D ₁ is a conditional expression.

It is desirable to satisfy. In addition, when the thickness of the first substrate and the second substrate is D ₂ , the thickness D ₂ is the following conditional formula

It is desirable to satisfy.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 2, the high-density optical disc of the double-sided two-layer structure according to the first embodiment of the present invention is composed of three pieces, and includes first and second information substrates 111 and 121 on which one side of the information signal is recorded. And a third information substrate 131 disposed between the first information substrate 111 and the second information substrate 121 and having information signals recorded on both surfaces thereof.

The first information substrate 111 has a first incident surface 111a on which the recording / reproducing light L is incident, and a first recording surface 111b on which an information signal is recorded. A first reflective layer 113 is formed on the first recording surface 111b to reflect part of incident light and transmit the remaining part toward the third information substrate 131.

The first information substrate 111 is made of any one material selected from polycarbonate (PC), polymethyl methacrylate (PMMA), amorphous polyolefin (APO), and glass materials. When the thickness of the first information substrate 111 is D ₁ , the thickness is preferably set in the setting of the thickness as shown in Equation 1 in consideration of the tilt margin of the optical disk. Do.

In this case, when used exclusively for reproduction, the first recording surface 111b forms a desired physical pit on the material of the first information substrate 111 itself, without adding another configuration, and the formation thereof is completed. do. On the other hand, in the case of forming a structure capable of recording and reproducing by using a phase change method, a dielectric film made of ZnS-SiO ₂ material or a GeSbTe system is formed between the first recording surface 111b and the first reflection layer 113. Alternatively, a recording film and a dielectric film made of AgInSbTe-based material are stacked in this order. Since the configuration of such a phase change film itself is well known, its detailed description and drawings will be omitted.

The first reflective layer 113 is a translucent film, and is preferably made of any one material selected from silver (Ag), Ag alloy of AgPdCu system, SiC, AlN, and Au alloy. In addition, the first reflecting layer 113 is set to a different thickness depending on the material selected to obtain approximately 28% of the reflectance required to reproduce the information recorded on the first recording surface 111b. For example, when AgPdCu material is selected, the reflectance of approximately 28% can be obtained by setting the thickness to approximately 20 nm and the Al reflecting film to approximately 60 nm.

The second information substrate 121 has a second incident surface 121a through which the recording / reproducing light L is incident, and a second recording surface 121b on which the information signal is recorded. A second reflection layer 123 is formed on the second recording surface 121b to reflect part of the incident light.

Like the first information substrate 111, the second information substrate 121 is made of any one material selected from polycarbonate (PC), polymethyl methacrylate (PMMA), amorphous polyolefin (APO), and glass materials. In addition, when the thickness is D ₁ , it is set as shown in Equation 1 above. In the recording / reproducing of the information on the second information substrate 121, the configuration in the case of being used exclusively for reproduction and the configuration in which both recording and reproduction are possible are as described with reference to the first information substrate 111. Since it is substantially the same, detailed description is abbreviate | omitted. In addition, the second reflective layer 123 is a translucent film and is formed of a material substantially the same as the material of the first reflective layer 113 described above.

The third information substrate 131 is formed to be bonded between the first reflection layer 113 and the second reflection layer 123, and the information signal is recorded / reproduced by the light transmitted through the first reflection layer 113. And a third recording surface 131a and a fourth recording surface 131b in which the information signal is recorded / reproduced by the light transmitted through the second reflection layer 123. Like the first information substrate 111, the third information substrate 131 is made of any one material selected from polycarbonate (PC), polymethyl methacrylate (PMMA), amorphous polyolefin (APO), and glass materials. In this configuration, the high-density optical disc has a thickness of approximately 0.6 mm so that the overall thickness D satisfies a standard disc, i.e., 1.2 mm, such as a CD or DVD.

A third reflective layer 133 is formed on the third recording surface 131a, and a fourth reflective layer 135 is formed on the fourth recording surface 131b. The third and fourth reflection layers 133 and 135 are made of a material such as Al alloy and Ag alloy as a total reflection film.

In the case where the third information substrate 131 is used for reproduction only, the configuration is completed by forming physical pits for the third and fourth recording surfaces 131a and 131b. On the other hand, in order to be able to record and reproduce at least one recording surface of the third information substrate 131, a film of a phase change film is required on the third reflection layer 133 and / or the fourth reflection layer 135. That is, a phase change film may be formed by stacking on the third reflection layer 133 and / or the fourth reflection layer 135 in the order of a dielectric film, a recording film, and a dielectric film.

As described above, the configured optical disk is formed to be bonded through two bonding processes, and spacers 141 and 143 having a predetermined thickness are required at the time of bonding by the bonding material. Here, the spacers 141 and 143 are required to be bonded between the first reflection layer 113 and the third reflection layer 133, and between the fourth reflection layer 135 and the second reflection layer 123, and have an overall thickness. It is preferable to have a thickness of approximately 20 to 40 µm which is a range that does not affect the setting of D.

Here, the first to third information substrates 111, 121 and 131 have a thickness in units of 10 ^-1 mm order, and the first to fourth reflection layers 113, 123, 133, and 135 ) And the spacers 141 and 143 have a thickness in the order of tens of micrometers, so the total thickness D of the optical disc is determined by the thicknesses of the first to third information substrates 111, 121, and 131. do. On the other hand, in the above embodiment, the first information substrate 111 and / or the second information substrate 121 may be replaced by a dummy substrate without the information recording surface and the reflective layer.

Referring to FIG. 3, a high-density optical disk having a double-sided two-layer structure according to a second embodiment of the present invention is configured of four pieces, and includes first and second information substrates 211 and 221 on which information signals are written. And third and fourth information substrates 231 and 241 disposed between the first information substrate 211 and the second information substrate 221 and in which information signals are recorded on opposite surfaces thereof.

Each of the first and second information substrates 211 and 221 may include first and second incident surfaces 211a and 221a through which light L is incident, and first and second recording surfaces on which information signals are recorded. 211b) and 221b.

Each of the first recording surface 211b and the second recording surface 221b reflects a part of incident light, and the first and second rays transmit the remaining light toward the third and fourth information substrates 231 and 241, respectively. Reflective layers 213 and 223 are formed.

In this case, each of the first and second information substrates 211 and 221 and the first and second reflection layers 213 and 223 may be the first and second information substrates 111 and 121 according to the first embodiment. Since the first and second reflective layers 113 and 123 have substantially the same structure, detailed description thereof will be omitted.

The optical disc according to the present embodiment is characterized in that the third information substrate 131 disclosed in the first embodiment is manufactured by dividing into two information substrates 231 and 241 and bonded to each other. The third information substrate 231 is disposed to face the first recording surface 211b and has a third recording surface 231a in which an information signal is recorded / reproduced by light transmitted through the first reflection layer 213. A third reflection layer 233 is formed on the third recording surface 231a to reflect incident light.

The fourth information substrate 241 is formed to be bonded between the second information substrate 221 and the third information substrate 231, and is disposed to face the second recording surface 221b so as to face the second reflection layer 223. And a fourth recording surface 241b in which the information signal is recorded / reproduced by the light passing through. A fourth reflective layer 243 reflecting incident light is formed on the fourth recording surface 241b.

Here, the thickness from the first incident surface 211a to the first recording surface 211b and the thickness from the second incident surface 221a to the second recording surface 221b is D ₁ . D ₁ preferably satisfies Equation ₁ described above.

The material of each of the third and fourth information boards 231 and 241 is formed of substantially the same material as the third information board 131 in the first embodiment, and the thickness of each of the third and fourth information boards 231 and 241 is the total thickness of the high density optical disk. It has a thickness of approximately 0.3 mm so that D satisfies 1.2 mm, which is a standard such as a CD or DVD.

Each of the third and fourth reflective layers 233 and 243 has substantially the same configuration as the third and fourth reflective layers 133 and 135 of the first embodiment, and thus detailed description thereof will be omitted.

As described above, the configured optical disk is formed to be bonded through three bonding processes, and spacers 251, 253 and 255 of a predetermined thickness are required for bonding by the bonding material. Here, the spacers 251, 253, and 255 are formed between the first reflection layer 213 and the third reflection layer 233, between the third information substrate 231 and the fourth information substrate 241, and the fourth reflection layer. It is required at the time of bonding between 243 and the second reflection layer 223, and preferably has a thickness of approximately 20 to 40 µm which is a range that does not affect the setting of the overall thickness D.

In this way, the third information board structure of the first embodiment in which the information recording surface is formed on both sides is produced by dividing the third and fourth information substrates having the information recording surface in the cross-section, and then bonded to each other to produce the information board located in the middle. Therefore, there is an advantage that the manufacturing process using the stamper can be facilitated.

Referring to FIG. 4, the high-density optical disc of the double-sided two-layer structure according to the third embodiment of the present invention is composed of three pieces, and includes first and second information substrates 311 (1) on which information signals are recorded. 321, and a third information substrate 331 disposed between the first information substrate 311 and the second information substrate 321 and in which an information signal is recorded on the opposite surface.

Each of the first and second information substrates 311 and 321 includes first and second incident surfaces 311a and 321a to which light L is incident, and first and second recording surfaces on which information signals are recorded. 311b) 321b.

Each of the first and second recording surfaces 311b and 321b reflects a part of incident light, and the first and second reflection layers 313 and 323 respectively transmit the remaining light toward the third information substrate 331. ) Is formed. Here, each of the first and second information substrates 311 and 321, and the first and second reflection layers 313 and 323 may be the first and second information substrates 111 and 121 according to the first embodiment. Since the first and second reflective layers 113 and 123 have substantially the same structure, detailed description thereof will be omitted.

In addition, the third information substrate 331 is provided with third and fourth recording surfaces 331a and 331b capable of recording information signals, and each of the third and fourth recording surfaces 331a and 331b is provided with a third information substrate 331a and 331b. Third and fourth reflective layers 333 and 335 are formed. The material of the third information substrate 331 and the material and configuration of the third and fourth reflection layers 333 and 335 are the third information substrate 131 and the third and fourth reflection layers according to the first embodiment. Since it is substantially the same as (133) and 135, the detailed description is abbreviate | omitted.

The optical disk according to the present embodiment is characterized in that the thicknesses of the first to third information substrates 311, 321, and 331 are set differently from those of the first embodiment.

In other words, when the thickness of each of the first and second information substrates 311 and 321 is D ₂ , the first and second information substrates 311 and 321 are represented by Equation 2 in consideration of the tilt margin of the optical disk in setting the thickness. Similarly, the thickness is preferably set.

As described above, the configured optical disk is formed to be bonded through two bonding processes, and spacers 341 and 343 having a predetermined thickness are required for bonding by the bonding material. Here, the spacers 341 and 343 are required to be bonded between the first reflection layer 313 and the third reflection layer 333 and between the fourth reflection layer 343 and the second reflection layer 323. It is preferable to have a thickness of approximately 20 to 40 µm which is a range that does not affect the setting of D.

In this way, by resetting the thickness of the information board, it is possible to overcome the problems caused by the tilt of the optical disc and to have four information recording planes. Large capacity can be achieved. Also in this third embodiment, the first information substrate 311 and / or the second information substrate 321 may be replaced with a dummy substrate without an information signal recording surface or a reflective layer.

Referring to FIG. 5, the high-density optical disk having a two-sided double-layer structure according to the fourth embodiment of the present invention is composed of three pieces, and includes first and second information substrates 411 and 431 in which information signals are recorded on one surface thereof. And a dummy substrate 431 bonded to the rear surface of the second information substrate 431 opposite to the second recording surface 431a. The first information substrate 411 has a first incident surface 411a through which light L is incident and a first recording surface 411b on which an information signal is recorded. A first reflection layer 413 is formed on the first recording surface 411b so as to reflect part of incident light and transmit the rest toward the second information substrate 431. Here, since the first information substrate 411 and the first reflection layer 413 have substantially the same structure as the first information substrate 111 and the first reflection layer 113 described in the first embodiment, the detailed description thereof will be made. Omit.

The second information substrate 431 is bonded to the first information substrate 411 and has a second recording surface 431a in which an information signal is recorded / reproduced by light transmitted through the first reflection layer 413. . On the second recording surface 431a, a second reflection layer 433 reflecting the incident light L is formed. The material and configuration of the second information substrate 431 and the second reflection layer 433 are substantially the same as those of the third information substrate 131 and the third reflection layer 133 described in the first embodiment, and thus the detailed description thereof will be omitted. Omit.

The optical disk according to the present embodiment is distinguished from the third embodiment in that it has a structure adapted to correspond to a high-density optical disk having a double-sided double-sided structure. The dummy substrate 421 is provided on the rear surface of the information substrate 431.

When the thickness of each of the first information substrate 411 and the dummy substrate 443 is D ₂ , the thickness of the first information substrate 411 and the dummy substrate 443 is set as Equation 2 in consideration of the tilt margin of the optical disk. It is preferable to be.

As described above, the configured optical disk is formed to be bonded through two bonding processes, and spacers 441 and 443 having a predetermined thickness are required for bonding by the bonding material. Here, the spacers 441 and 443 are required to be bonded between the first reflection layer 413 and the second reflection layer 433, and between the second information substrate 431 and the dummy substrate 421. It is preferable to have a thickness of approximately 20 to 40 µm which is a range that does not affect the setting of D.

6, the high-density optical disc according to the fifth embodiment of the present invention is composed of three pieces, one side having a two-layer structure, and the other side having a single layer structure. The optical disc according to the fifth embodiment is disposed between the first and second information substrates 511 and 521 on which information signals are recorded on one surface, and between the first information substrate 511 and the second information substrate 521. And a third information substrate 531 on which information signals are recorded. Each of the first and second information substrates 511 and 521 includes first and second incident surfaces 511a and 521a to which light L is incident, and first and second recording surfaces on which information signals are recorded. 511b and 521b.

A first reflection layer 513 is formed on the first recording surface 511b so as to reflect part of incident light and transmit the rest toward the third information substrate 531. In addition, a second reflection layer 513 is formed on the second recording surface 521b to reflect incident light. Here, each of the first and second information substrates 511, 521, and the first reflection layer 513 may be the first and second information substrates 111, 121, and the first reflection layer described in the first embodiment. 113) and substantially the same structure, detailed description thereof will be omitted.

The third information substrate 531 is provided with a third recording surface 531a through which the information signal can be recorded, and a third reflection layer 533 is formed on the third recording surface 531a. The material and configuration of the third information substrate 531 and the third reflection layer 533 are substantially the same as those of the third information substrate 131 and the third reflection layer 133 according to the first embodiment, and thus a detailed description thereof is omitted. do.

Here, when the thickness of each of the first information substrate 511 and the second information substrate 521 is D ₂ , the equation 2 and the above equation are considered in consideration of the tilt margin of the optical disc in setting the thickness. It is preferable to set the same.

As described above, the configured optical disk is formed to be bonded through two bonding processes, and spacers 541 and 543 having a predetermined thickness are required for bonding by the bonding material. Here, the spacers 541 and 543 are required to be bonded between the first reflective layer 513 and the third reflective layer 533, and between the third information substrate 531 and the second reflective layer 523. It is preferable to have a thickness of approximately 20 to 40 µm which is a range that does not affect the setting of the thickness D.

Referring to FIG. 7, the high-density optical disk according to the sixth embodiment of the present invention is composed of three pieces having a double-sided one-layer structure. The dummy substrate 631 is disposed between the first information substrate 611 and the second information substrate 621. Each of the first and second information substrates 611 and 621 includes first and second incident surfaces 611a and 621a to which light L is incident, and first and second recording surfaces on which information signals are recorded. 611b) and 621b. First and second reflecting layers 613 and 623 are formed on each of the first and second recording surfaces 611b and 621b to reflect incident light. Here, the materials and structures of the first and second information substrates 611 and 621 are substantially the same as the first and second information substrates 111 and 121 described in the first embodiment. Since each of the second reflective layers 613 and 623 is substantially the same as the third reflective layer 133 described in the first embodiment, detailed description thereof will be omitted.

The optical disk according to the present embodiment is distinguished from the above-described embodiments in that it has a structure adapted to correspond to a high-density optical disk having a double-sided one-layer structure. It is characterized in that a dummy substrate 631 is provided between the first and second information substrates 611 and 621.

Here, when the thickness of each of the first information substrate 611 and the second information substrate 621 is D ₂ , the equation 2 and the above equation are considered in consideration of the tilt margin of the optical disc in setting the thickness. It is preferable to set the same.

As described above, the configured optical disk is formed to be bonded through two bonding processes, and spacers 641 and 643 having a predetermined thickness are required at the time of bonding by the bonding material. Here, the spacers 641 and 643 are required to be bonded between the first reflective layer 613 and the dummy substrate 631, and the lesser substrate 631 and the second reflective layer 623. It is preferable to have a thickness of approximately 20 to 40 µm which is a range that does not affect the setting of.

Accordingly, by setting the thicknesses D ₁ and D ₂ of the information substrate as shown in Equation 1 or 2 above while maintaining the overall thickness of the disc in accordance with the CD and DVD standards, the tilt margin of the optical disc can be secured largely. It can overcome the problem caused by. In addition, by securing two to four information recording surfaces, a large capacity of recording capacity of up to 50 gigabytes is possible.

Claims (20)

A first information substrate having a first entrance surface to which recording / reproducing light is incident and a first recording surface on which an information signal is recorded; A first reflection layer formed on the first recording surface and reflecting a part of the incident light; A second information substrate having a second entrance surface on which recording / reproducing light is incident, and a second recording surface on which an information signal is recorded; A second reflection layer formed on the second recording surface and reflecting a part of the incident light; A third recording surface which is formed between the first information substrate and the second information substrate, and has an information signal recorded / reproduced by light transmitted through the first reflection layer, and an information signal by light transmitted through the second reflection layer; A third information substrate having a fourth recording surface on which is recorded / reproduced; A third reflection layer formed on the third recording surface to reflect incident light; And a fourth reflection layer formed on the fourth recording surface to reflect incident light. When the thickness from the first incident surface to the first recording surface and the thickness from the second incident surface to the second recording surface are D ₁ , A thickness D ₁ is a high density optical disc, characterized in that the following conditional expression is satisfied. <Conditional expression>

The method of claim 1, wherein each of the first to third information substrates, A high density optical disc comprising any one selected from polycarbonate (PC), polymethyl methacrylate (PMMA), amorphous polyolefin (APO) and glass materials. The method according to claim 1 or 2, And a spacer thickness required for bonding between the first reflective layer and the third reflective layer and between the fourth reflective layer and the second reflective layer is approximately 20 to 40 μm. A first information substrate having a first entrance surface to which recording / reproducing light is incident and a first recording surface on which an information signal is recorded; A first reflection layer formed on the first recording surface and reflecting a part of the incident light; A second information substrate having a second entrance surface on which recording / reproducing light is incident, and a second recording surface on which an information signal is recorded; A second reflection layer formed on the second recording surface and reflecting a part of the incident light; A third information substrate bonded to a first reflection layer of the first information substrate, the third information substrate having a third recording surface disposed opposite to the first recording surface and having an information signal recorded / reproduced by light transmitted through the first reflection layer; ; A third reflection layer formed on the third recording surface to reflect incident light; A fourth recording surface which is formed between the second information substrate and the third information substrate, and has a fourth recording surface which is disposed to face the second recording surface so that the information signal is recorded / reproduced by light transmitted through the second reflective layer. 4 information board; And a fourth reflection layer formed on the fourth recording surface to reflect incident light. When the thickness from the first incident surface to the first recording surface and the thickness from the second incident surface to the second recording surface are D ₁ , A thickness D ₁ is a high density optical disc, characterized in that the following conditional expression is satisfied. <Conditional expression>

The method of claim 1, wherein each of the first to fourth information substrates, A high density optical disc comprising any one selected from polycarbonate (PC), polymethyl methacrylate (PMMA), amorphous polyolefin (APO) and glass materials. The method according to claim 4 or 5, A high-density optical disc, characterized in that the spacer thickness required for bonding between the first reflective layer and the third reflective layer, between the third information substrate and the fourth information substrate, and between the fourth reflective layer and the second reflective layer is approximately 20 to 40 μm. . A first information substrate having a first entrance surface to which recording / reproducing light is incident and a first recording surface on which an information signal is recorded; A first reflection layer formed on the first recording surface and reflecting a part of the incident light; A second information substrate having a second entrance surface on which recording / reproducing light is incident, and a second recording surface on which an information signal is recorded; A second reflection layer formed on the second recording surface and reflecting a part of the incident light; A third recording surface formed between the first information substrate and the second information substrate, the third recording surface having the information signal recorded / reproduced by the light transmitted through the first reflective layer, and the information signal by the light transmitted through the second reflective layer; A fourth information substrate having a fourth recording surface on which is recorded / reproduced; A third reflection layer formed on the third recording surface to reflect incident light; And a fourth reflection layer formed on the fourth recording surface to reflect incident light. When the thickness from the first incident surface to the first recording surface and the thickness from the second incident surface to the second recording surface are D ₂ , A high density optical disc, characterized in that the thickness D ₂ satisfies the following conditional expression. <Conditional expression>

The method of claim 7, wherein each of the first to third information substrate, A high density optical disc comprising any one selected from polycarbonate (PC), polymethyl methacrylate (PMMA), amorphous polyolefin (APO) and glass materials. The method according to claim 7 or 8, The spacer density required for bonding between the first reflective layer and the third reflective layer and between the fourth reflective layer and the second reflective layer is about 20 to 40 μm. A first information substrate having an incident surface on which recording / reproducing light is incident and a first recording surface on which an information signal is recorded; A first reflection layer formed on the first recording surface and reflecting a part of the incident light; A second information substrate bonded to the first information substrate, the second information substrate having a second recording surface on which the information signal is recorded / reproduced by light transmitted through the first reflection layer; A second reflection layer formed on the second recording surface to reflect incident light; And a dummy substrate bonded to a rear surface of the second information substrate opposite to the second recording surface. When the thickness from the light incident surface of the first information substrate to the first recording surface and the thickness of the dummy substrate are D ₂ , A high density optical disc, characterized in that the thickness D ₂ satisfies the following conditional expression. <Conditional expression>

The method of claim 10, wherein the first information substrate and the second information substrate, A high density optical disc comprising any one selected from polycarbonate (PC), polymethyl methacrylate (PMMA), amorphous polyolefin (APO) and glass materials. The method according to claim 10 or 11, wherein And a spacer thickness required for bonding between the first reflective layer and the second reflective layer and between the second information substrate and the dummy substrate is approximately 20 to 40 μm. A first information substrate having a first entrance surface to which recording / reproducing light is incident and a first recording surface on which an information signal is recorded; A first reflection layer formed on the first recording surface and reflecting a part of the incident light; A second information substrate having a second entrance surface on which recording / reproducing light is incident, and a second recording surface on which an information signal is recorded; A second reflection layer formed on the second recording surface to reflect incident light; A third information substrate formed between the first information substrate and the second information substrate, the third information substrate having a third recording surface on which information signals are recorded / reproduced by light transmitted through the first reflection layer; And a third reflection layer formed on the third recording surface to reflect incident light. When the thickness from the first incident surface to the first recording surface and the thickness from the second incident surface to the second recording surface are D ₂ , A high density optical disc, characterized in that the thickness D ₂ satisfies the following conditional expression. <Conditional expression>

The method of claim 13, wherein each of the first to third information substrate, A high density optical disc comprising any one selected from polycarbonate (PC), polymethyl methacrylate (PMMA), amorphous polyolefin (APO) and glass materials. The method according to claim 13 or 14, And a spacer thickness required for bonding between the first reflective layer and the third reflective layer and between the third information substrate and the second reflective layer is approximately 20 to 40 μm. A first information substrate having a first entrance surface to which recording / reproducing light is incident and a first recording surface on which an information signal is recorded; A first reflection layer formed on the first recording surface to reflect incident light; A second information substrate having a second entrance surface on which recording / reproducing light is incident, and a second recording surface on which an information signal is recorded; A second reflection layer formed on the second recording surface to reflect incident light; And a dummy substrate bonded to the first reflection layer and the second reflection layer to maintain a predetermined thickness of the entire optical disk. When the thickness from the first incident surface to the first recording surface and the thickness from the second incident surface to the second recording surface are D ₂ , A high density optical disc, characterized in that the thickness D ₂ satisfies the following conditional expression. <Conditional expression>

The method of claim 16, wherein the first information substrate and the second information substrate, A high density optical disc comprising any one selected from polycarbonate (PC), polymethyl methacrylate (PMMA), amorphous polyolefin (APO) and glass materials. The method according to claim 16 or 17, And a spacer thickness required for bonding between the first reflective layer and the dummy substrate and the dummy substrate and the second reflective layer is about 20 to 40 μm. A first substrate having a first incident surface on which recording / reproducing light is incident; A second substrate having a second incident surface on which recording / reproducing light is incident; A first recording surface which is formed between the first substrate and the second substrate, the first recording surface on which an information signal is recorded / reproduced by light incident through the first incident surface, and information by light incident through the second incident surface; An information substrate having a second recording surface on which signals are recorded / reproduced; A first reflection layer formed on the first recording surface to reflect incident light; And a second reflection layer formed on the second recording surface to reflect incident light. When the thickness of the first substrate and the second substrate is D ₁ , A thickness D ₁ is a high density optical disc, characterized in that the following conditional expression is satisfied. <Conditional expression>

A first substrate having a first incident surface on which recording / reproducing light is incident; A second substrate having a second incident surface on which recording / reproducing light is incident; A first recording surface which is formed between the first substrate and the second substrate, the first recording surface on which an information signal is recorded / reproduced by light incident through the first incident surface, and information by light incident through the second incident surface; An information substrate having a second recording surface on which signals are recorded / reproduced; A first reflection layer formed on the first recording surface to reflect incident light; And a second reflection layer formed on the second recording surface to reflect incident light. When the thickness of the first substrate and the second substrate is D ₂ , A high density optical disc, characterized in that the thickness D ₂ satisfies the following conditional expression. <Conditional expression>

Images