KR100269123B1 - Optical disk - Google Patents

Abstract

Disclosed is an optical disc in which the thickness of the information substrate with respect to the entire thickness is reset so as to overcome the problems caused by the tilt of the optical disc and to store approximately 15 gigabytes or more of information on each information recording surface.

The disclosed optical disc includes: an information substrate having an incident surface on which recording / reproducing light is incident and a recording surface on which an information signal is recorded; An optical disc comprising at least one reflective layer coated on a recording surface and reflecting at least a portion of incident light, wherein the overall thickness of the optical disc is D and the thickness from the incident surface of the information substrate to the recording surface is D1. ~ = ~ D_1 ~ / ~ D ~ <= ~ 0.38 is characterized in that it is satisfied.

In addition, the disclosed optical disc includes a first information substrate having an incident surface on which recording / reproducing light is incident, a first recording surface on which an information signal is recorded, and a first formed on the first recording surface to reflect a part of the incident light. A reflective layer; A second information substrate having a second recording surface on which an information signal is recorded; A second reflecting layer formed on the second recording surface and reflecting at least a part of the incident light, wherein the overall thickness of the optical disc is D, and the thickness from the incident surface to the first recording surface of the first information substrate is D1. = ~ D_1 ~ / ~ D ~ <= ~ 0.38 is characterized in that it is satisfied.

Description

Optical disk

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high density optical disc, and more particularly, to an optical disc which minimizes the influence of the tilt of the optical disc by resetting the thickness of the information substrate for the entire thickness 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 optical disc (CD) and a digital multifunction optical 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 Optical disc diameter (mm) 120 120 Optical disc 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 optical disc diameter and the optical 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 optical disc player, the specification of the optical disc tray for loading / unloading the optical disc, and the like.

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 optical 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 an optical disc with a thickness of 1.2 mm or less, so that the optical disc thickness was 1.2 mm to minimize degradation of a 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, the tolerance of the optical disc inclination due to the densification becomes small, so that there is a high possibility that an error occurs during information recording / reproducing. In view of this, the board thickness of the DVD has been standardized to 0.6 mm. Here, the DVD records the signal digitally, so that signal degradation due to contamination of the optical disk surface can be processed in a circuit.

DVDs having the above-described standards may be divided into single-sided single-layered structures, double-sided single-layered structures, single-sided two-layered structures and double-sided two-layered structures, as shown in FIGS.

Referring to FIG. 1, a DVD having a single-sided single-sided structure is coated with an information board 1 having a thickness of 0.6 mm having a recording surface 1a on which an information signal is recorded on the back surface on which light L is incident, and the recording surface 1a. The reflective layer 3 formed, the protective layer 5 for preventing oxidation or damage of the reflective layer 3, the bonding layer 7, and the total thickness of the optical disc conform to the standard, and the bending of the information substrate 1 It consists of a protective substrate 9 bonded to the protective layer 5 by the bonding layer 7 so as to prevent the back. This single-sided single-layered optical disc has an information recording capacity of 4.7 gigabytes of information.

Referring to FIG. 2, the double-sided single layer DVD has a recording surface 11a of each of the first and second information substrates 11 and 21 and the first and second information substrates 11 and 21 having a thickness of 0.6 mm. And a bonding layer 15 provided between the first and second reflection layers 13 and 23 coated on the surface 21a and the first and second reflection layers 13 and 23. In this way, the optical disc of the double-sided one-layer structure has an information recording capacity of about 9.4 gigabytes, which is twice the information capacity of the single-sided one-layer structure.

Referring to FIG. 3, a DVD having a two-sided cross-sectional structure includes a first information substrate 31 having a thickness of 0.6 mm, a translucent layer 33 coated on the first recording surface 31a of the first information substrate 31, and And a second information substrate 35 formed on the translucent layer 33 by a 2P (Photo Polymer) process and having a second recording surface 35a and coated on the second recording surface 35a. A protective substrate 39 bonded by a reflective layer 37, a bonding layer 38, and the bonding layer 38, and protecting the first and second information substrates 31 and 35. It is composed. In this case, the sum of the information recording capacities recorded on the first and second recording surfaces 31a and 35a has approximately 8.5 gigabytes.

Referring to FIG. 4, a double-sided double-layer DVD includes two optical discs 41 and 45 having a structure in which a protective substrate is excluded from the single-sided double-layer DVD in FIG. 3, and the optical discs 41 and 45 are bonded to each other. It consists of the bonding layer 43. This double-sided two-layer DVD has twice the information capacity of a single-sided two-layer DVD, that is, 17 gigabytes.

The DVD having the structure as described above has the advantage that the information capacity is larger than that of the conventional CD by maintaining the total thickness of 1.2 mm by bonding the information substrate and / or protective substrate having a thickness of 0.6 mm.

However, as described above, when the thickness of the information substrate is normalized to 0.6 mm, that is, when the thickness ratio of the information substrate to the total thickness is maintained at about 0.5, a short wavelength optical pickup of about blue wavelength region (about 410 nm) is performed. In the case of high density information recording / reproducing at the level of 15 gigabyte per side, the allowable range of the optical disc inclination which does not affect the recording / reproducing is drastically reduced. This is because the amount of coma aberration according to the tilt of the optical disk is proportional to the wavelength, inversely proportional to the third power of the objective lens numerical aperture, and inversely proportional to the optical disk thickness.

Therefore, even when a light source having a condition suitable for high density optical information recording and an optical pickup device having an objective lens are employed, the DVD having the above-described structure is adopted in which the thickness of the information substrate is normalized to 0.6 mm. In the case of employing the optical disc, the optical disc tilt allowance is reduced. Accordingly, it is impossible to record / reproduce high-density information at the level of 15 gigabytes per side.

Accordingly, an object of the present invention is to provide an optical disc having an improved structure to have an information capacity of 15 gigabytes or more per side while having the same size as a DVD and a CD.

1 is a schematic cross-sectional view showing a conventional cross-sectional one-layer optical disk.

Figure 2 is a schematic cross-sectional view showing a conventional double-sided one-layered optical disk.

Figure 3 is a schematic cross-sectional view showing a conventional cross-section two-layer optical disk.

Figure 4 is a schematic cross-sectional view showing a conventional double-sided two-layer structure optical disk.

Figure 5 is a schematic cross-sectional view showing a cross-sectional one-layer structure optical disk according to an embodiment of the present invention.

Figure 6 is a schematic cross-sectional view showing a double-sided one-layer optical disk according to an embodiment of the present invention.

Figure 7 is a schematic cross-sectional view showing a cross-sectional double-layer structure optical disk according to an embodiment of the present invention.

8 is a schematic cross-sectional view showing a double-sided two-layered optical disk according to an embodiment of the present invention.

<Description of the code | symbol about the principal part of drawing>

51 Information board 53 ... Reflective layer

55 ... protective layer 57 ... bonding layer

59.Protective board 61 ... 1st information board

61 '... 2nd Information Board 63 ... 1st Reflector

63 '... 2nd reflective layer 65 ... 1st bonding layer

65 '... second bonding layer 67 ... spacer

71 First Information Substrate 73 First Reflection Layer

75 ... bonding layer 77 ... second reflection layer

79 ... 2nd Information Board 81 ... 1st Information Board

83 ... 1st reflective layer 85 ... 1st bonding layer

87 The Third Reflector 89 The Third Information Board

91 ... Second Information Substrate 93 ... Second Reflection Layer

95 second bonding layer 97 fourth reflecting layer

In order to achieve the above object, the present invention includes an information substrate having an incident surface on which recording / reproducing light is incident and a recording surface on which an information signal is recorded; An optical disc comprising at least one reflective layer coated on the recording surface and reflecting at least a portion of incident light, wherein the overall thickness of the optical disc is D, and the thickness from the incidence surface to the recording surface of the information substrate is D1. In this case, it is characterized by satisfying the conditional expression 0.20 ~ = ~ D_1 ~ / ~ D ~ <= ~ 0.38.

In addition, an optical disc according to the present invention has a first information substrate having an incident surface on which recording / reproducing light is incident, a substrate having a first recording surface on which an information signal is recorded, and a part of the incident light formed on the first recording surface. A first reflecting layer for reflecting; A second information substrate having a second recording surface on which an information signal is recorded; A second reflecting layer formed on the second recording surface and reflecting at least a portion of incident light, wherein an overall thickness of the optical disc is referred to as D, and a thickness from the incidence surface to the first recording surface of the first information substrate is D1; , Conditional expression 0.20 ~ = ~ D_1 ~ / ~ D ~ <= ~ 0.38

In addition, an 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 incident surface on which recording / reproducing light is incident, a second recording surface on which an information signal is recorded, and a second reflecting layer formed on the second recording surface to reflect a part of the incident light; A third recording surface which is formed between the first information substrate and the second information substrate, the third recording surface on which the information signal is recorded / reproduced by the light transmitted through the first information substrate, and the light transmitted through the second information substrate. A third information substrate having a fourth recording surface on which information signals are recorded / reproduced; A third reflection layer formed on the third recording surface and reflecting at least a portion of incident light; And a fourth reflection layer formed on the fourth recording surface to reflect at least a part of the incident light, wherein an overall thickness of the optical disk is referred to as D, and the thickness from the light incident surface of the first information substrate to the first recording surface and the first reflection layer. When the thickness from the light incident surface of the information board to the second recording surface is D1, the conditional expressions 0.20 to = ~ D_1 to / ~ D to <= to 0.38 are satisfied.

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

Referring to FIG. 5, an optical disk having a single-layered cross-sectional structure according to an embodiment of the present invention includes an information substrate 51 having an incident surface on which light L is incident, a recording surface 51a on which an information signal is recorded, and the recording surface. A reflective layer 53 coated on the 51a, a protective layer 55 formed on the reflective layer 53 to prevent oxidation or damage of the reflective layer 53, a bonding layer 57, and the bonding layer ( And a protective substrate 59 bonded to the protective layer 55 by the 57 to protect the information substrate 51. Herein, the information substrate 51 and the protective substrate 59 have a thickness in millimeters, and the reflective layer 53, the protective layer 55, and the bonding layer 57 have a thickness in micrometers. The overall thickness of the optical disc of the single-sided single layer structure is determined by the thicknesses of the information substrate 51 and the protective substrate 59.

Here, when the total thickness of the optical disk is referred to as D, and the thickness from the incident surface 51b to the recording surface 51a of the information substrate 51 is D1, the following expression 1 is satisfied.

0.20 ~ = ~ D_1 ~ / ~ D ~ <= ~ 0.38

Here, if the value falls outside the lower limit value, it is difficult to obtain a good signal when a defect occurs due to scratches or contamination on the optical disc incident surface. If the upper limit value is out of range, the optical disc tilt allowable range is within the range of the optical disc manufacturing error due to coma aberration, and thus it is difficult to obtain a good signal. Accordingly, when the upper and lower limit values of Equation 1 are exceeded, even when the optical disc and the optical pickup as shown in Table 2 are satisfied to increase the information capacity of the optical disc, the signal is out of the inclination range of the optical disc and the actual signal is reproduced. This is impossible.

When the total thickness D of the optical disc is a conventional optical disc, that is, a standard such as CD or DVD, the thickness D1 of the information substrate may be expressed by Equation 2.

0.24 ~ = ~ D_1 ~ <= ~ 0.456 ~~~ [mm]

The information capacity of the optical disc is determined by the specifications of the optical pickup device such as the wavelength of the light source, the numerical aperture of the objective lens, and the specifications such as the track pitch and the minimum fit size of the optical disc. That is, it is preferable that the wavelength of the optical disc and the light source suitable for the optical disc satisfies the standard example shown in Table 2 so as to have an information capacity of 15 gigabytes or more per side of the optical disc.

HD-DVD Optical disc diameter (mm) About 120 Optical disc thickness (mm) About 1.2 Information board thickness (mm) About 0.4 Track Pitch (μm) About 0.4 Minimum Feet Size (μm) About 0.23 Wavelength (nm) 410 Single Board Capacity (GB) About 15

Referring to FIG. 6, an optical disk having a double-sided single layer structure according to an embodiment of the present invention includes first and second information substrates 61 and 61 ′, and first and second information substrates 61 and 61 ′. A spacer 67 provided between the first and second reflection layers 63 and 63 'coated on the respective recording surfaces 61a and 61a', and between the first and second reflection layers 63 and 63 '. And first and second bonding layers 65 and 65 'for joining the first and second reflection layers 63 and 63' to the spacer 67. Here, the spacer 67 is a member provided to compensate for the sum of the thicknesses of the first and second information substrates 61 and 61 'is smaller than the total thickness of the optical disk.

Here, when the total thickness of the optical disk is D, and the thickness of each of the first and second information substrates 61 and 61 'is D1, the thickness of the information substrate with respect to the total thickness of the optical disk is represented by the above equation. It is preferable to satisfy 1.

Further, it is preferable that the optical disc data including the track pitch of the first and second recording surfaces 61a and 61a 'and the minimum pit size satisfy the above-mentioned standard of Table 2.

Referring to FIG. 7, an optical disk having a two-layered cross-sectional structure according to an embodiment of the present invention includes a first information substrate 71 having a first recording surface 71a, a first reflection layer 73, and a second recording surface 79a. And a second information substrate 79 having a second structure, a bonding layer 75 for joining the first information substrate 71 and the second information substrate 77, and a second reflection layer 77, wherein the optical disk has a total thickness. When D is referred to as D and the thickness from the light incident surface 71b of the first information substrate 71 to the first recording surface 71a is D1, the above expression (1) is satisfied.

The first information substrate 71 has an incidence surface 71b on which recording / reproducing light is incident and a first recording surface 71a on which an information signal is recorded.

The first reflection layer 73 is formed on the first recording surface 71a to reflect part of the incident light. For example, the first reflecting layer 73 reflects a part of incident light to the translucent film and transmits the remaining part toward the second recording surface 79a.

The second information substrate 79 has a second recording surface 79a on which an information signal is recorded. The second reflective layer 77 is formed on the second recording surface 79a side of the protective substrate 79 to reflect at least a part of the incident light. Here, the second reflection layer 77 reflects almost all of the incident light to the reflective film. On the other hand, the second reflection layer 77 is bonded to the first reflection layer 73 by the bonding layer 75.

Here, the distance between the first recording surface 71a and the second recording surface 79a is maintained at about 40 mu m.

It is preferable that the optical disc data including the track pitch of the first and second recording surfaces 71a and 79a and the minimum pit size satisfy Table 2.

In addition, since the second information substrate 77 includes a plurality of recording surfaces and reflective layers in addition to the second recording surface 79a and the second reflection layer 78 described above, an optical disk having a single-sided multilayer structure can be formed.

Referring to FIG. 8, an optical disc of a double-sided two-layer structure according to an embodiment of the present invention includes a first information substrate 81 having a first recording surface 81a, a first reflection layer 83, and the second recording surface ( A second information substrate 91 having a 91a, a second reflecting layer 83, and a third and fourth surface positioned between the first information substrate 81 and the second information substrate 91, respectively on both sides thereof. A third information substrate 89 having recording surfaces 89a and 89b, and third and fourth reflection layers 87 formed on each of the third and fourth recording surfaces 89a and 89b of the third information substrate 89; 97).

The first information substrate 81 has a first incident surface 81b on which the recording / reproducing light L is incident and a first recording surface 81a on which an information signal is recorded. The first reflecting layer 83 is formed on the first recording surface 81a to reflect part of the incident light and transmit the rest.

The second information substrate 91 has the same configuration as the first information substrate 81. That is, it has the 2nd incident surface 91b in which the recording / reproducing light L is incident, and the 2nd recording surface 91a in which the information signal is recorded. The second reflecting layer 93 is formed on the second recording surface 91a to reflect part of the incident light.

The third information substrate 89 is formed by bonding between the first information substrate 81 and the second information substrate 91 by the first and second bonding layers 85 and 95, respectively. A third recording surface 89a on which the information signal is recorded / reproduced by the light transmitted through the information substrate 81, and a fourth recording surface on which the information signal is recorded / reproduced by the light transmitted through the second information substrate 91; 89b is provided. The third reflection layer 87 is formed on the third recording surface 89a to reflect at least a portion of incident light, and the fourth reflection layer 97 is formed on the fourth recording surface 89b to form at least a portion of the incident light. Reflects. Here, the interval between the first recording surface 81a and the third recording surface 89a and the interval between the second recording surface 91a and the fourth recording surface 89b are kept approximately 40 占 퐉.

The total thickness of the optical disc is referred to as D, the thickness from the first incidence surface 81b of the first information substrate 81 to the first recording surface 81a and the second incidence surface of the second information substrate 91. When the thickness from (91b) to the second recording surface 91a is D1, it is preferable to satisfy the above expression (1).

It is preferable that the optical disc data including the track pitch of the first and second recording surfaces 81a and 91a and the minimum pit size satisfy Table 2 above.

In addition, the third and fourth recording surfaces 89a and 89b of the third information substrate 89 and the third and fourth reflection layers 87 and 97 may be formed of a plurality of layers.

Therefore, by resetting the thickness of the information substrate with respect to the total thickness of the optical disk, the problem caused by the tilt of the optical disk can be overcome, so that the optical disk can have an information capacity of 15 gigabytes or more per side. Therefore, in the case of an optical disk having a double-sided two-layer structure, the capacity of the recording capacity can be increased up to about 50 gigabytes.

In addition, there is an advantage in that an optical disk having a single-sided single layer structure, an optical disk having a single-sided double layer structure, an optical disk having a double-sided single layer structure, and an optical disk having a double-sided double layer structure without a photopolymer process.

Claims (11)

An information substrate having an incident surface on which recording / reproducing light is incident and a recording surface on which an information signal is recorded; An optical disc comprising at least one reflective layer formed on the recording surface and reflecting at least a portion of incident light. When the total thickness of the optical disk is D and the thickness from the incident surface of the information substrate to the recording surface is D1, Optical disc characterized by satisfying the conditional expression 0.20 ~ = ~ D_1 ~ / ~ D ~ <= ~ 0.38. The method of claim 1, A protective layer formed on the reflective layer to prevent oxidation or damage of the reflective layer; And a protective substrate bonded to the protective layer by a bonding layer to protect the information substrate. The method of claim 1, wherein the information board is provided with a pair, A spacer disposed between the pair of information substrates; And a bonding layer disposed between the spacer and each of the pair of information substrates to bond the information substrates and the spacers, wherein the two incidence surfaces of the information substrate are disposed to face each other. The method according to any one of claims 1 to 3, And the thickness D1 from the incidence surface to the recording surface of the information substrate is approximately 0.4 mm. The method according to any one of claims 1 to 3, And a track pitch formed on the recording surface is approximately 0.4 mu m, and a minimum pit size recorded on the track of the recording surface is approximately 0.23 mu m. A first information substrate having a substrate having an incident surface on which recording / reproducing light is incident, a first recording surface on which an information signal is recorded, and a first reflection layer formed on the first recording surface to reflect a part of the incident light; A second information substrate having a second recording surface on which an information signal is recorded; A second reflection layer formed on the second recording surface to reflect at least a portion of incident light; When the total thickness of the optical disc is D and the thickness from the incident surface of the first information substrate to the first recording surface is D1, An optical disc which satisfies the conditional expression 0.20 ~ = ~ D_1 ~ / ~ D ~ <= ~ 0.38. The method of claim 6, And the thickness D1 from the incidence surface of the first information substrate to the first recording surface is approximately 0.4 mm. The method according to claim 6 or 7, And a track pitch formed on the first and / or second recording surface is approximately 0.4 mu m, and a minimum pit size recorded on the track of the first and / or second recording surface is approximately 0.23 mu m. A first information substrate having a first entrance surface on which recording / reproduction 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, 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, the third recording surface on which the information signal is recorded / reproduced by the light transmitted through the first information substrate, and the light transmitted through the second information substrate. A third information substrate having a fourth recording surface on which information signals are recorded / reproduced; A third reflection layer formed on the third recording surface and reflecting at least a portion of incident light; A fourth reflection layer formed on the fourth recording surface to reflect at least a part of the incident light; When the total thickness of the optical disk is D, and each of 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 is D1, An optical disc which satisfies the conditional expression 0.20 ~ = ~ D_1 ~ / ~ D ~ <= ~ 0.38. The method of claim 9, And the thickness D1 is approximately 0.4 mm. The method of claim 9 or 10, The track pitch formed on at least one recording surface of the first to fourth recording surfaces is approximately 0.4 µm, and the minimum pit size recorded on the track of at least one recording surface of the first to fourth recording surfaces is approximately 0.23 µm. Optical disc.

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