KR100569399B1 - Disk for holographic rom disk and method for playback by using thereof - Google Patents

Abstract

The present invention relates to a holographic ROM disk and a reproducing method using the same. The holographic ROM disk structure of the present invention includes a first optical mirror layer through which reproducing light for holographic transmission is transmitted, and a substrate layer formed under the first optical mirror layer. And a recording material layer formed under the substrate layer and recording holographic data, and a second light mirror layer formed under the recording material layer and reflecting holographic reproduction light. Therefore, the present invention adds a second optical mirror layer on which the holographic light is reflected to the lower surface of the disk sequentially having the first optical mirror layer, the substrate layer, and the recording material layer, so that the angle of light incident on the disk is 22.5 degrees or less. By increasing the range of, the capacity of the data recorded on the holographic disc can be greatly increased.

Holographic ROM disk, optical mirror layer, angle of incidence, combo system

Description

Holographic ROM Disc and Playback Method Using It {DISK FOR HOLOGRAPHIC ROM DISK AND METHOD FOR PLAYBACK BY USING THEREOF}

1 is a schematic diagram showing a focusing and tracking servo control apparatus of a combo system of a holographic ROM and a digital data disc according to the prior art;

2 illustrates a holographic ROM disk structure and a playback process using the same according to an embodiment of the prior art;

3 is a diagram illustrating a holographic ROM disk structure and a playback process using the same according to another embodiment of the prior art;

4 is a view showing a holographic ROM disk structure and a playback process using the same according to the present invention;

5 is a schematic diagram showing a focusing and tracking servo control device of a combo system for playing a holographic ROM disc according to the present invention;

6 is a view for explaining a playback method using a holographic ROM disk according to the present invention;

<Description of Symbols for Main Parts of Drawings>

110: objective lens 119: spindle motor

300 Holographic ROM disk 302 First optical mirror (red)

304: substrate layer 306: recording material layer

308: second optical mirror (green)

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to disc technology in which optical data is recorded, and more particularly, to a holographic digital disc, a holographic ROM disc capable of reproducing data recorded thereon, and a reproduction method using the same.

In general, two or more different devices connected to one integrated system are called a combination system or a combo-system. Recently, as an example of a combination system, a system in which a digital data disk such as a holographic ROM disk and a DVD can be used in a single pickup device has emerged. Such a combo system includes servo control of tracking focus or tracking for different discs.

1 is a block diagram schematically illustrating a focusing and tracking servo control apparatus of a combo system of a holographic ROM and a digital data disc according to the prior art.

Referring to FIG. 1, a combo system having a servo control device includes a first light path S1 for causing the first light from the first light source 10 to enter the surface of the disk 2, and a second light source 30. A second light path S2 for injecting the second light from the light into the surface of the disc 2, and a first light detector PDIC1 44 for detecting the first light diffracted in the disc 2; And a second light detector (PDIC2) 26 for detecting the second light diffracted by the disc 2. Then, tracking and focus servo control of the digital data disc is performed according to the data detected by the second light detector PDIC2 26 and the holographic ROM disc is detected according to the data detected by the first light detector PDIC1 44. It further includes a control unit 28 to perform the focus servo control.

로 변형하는 변형판(quarter wave plate)(18)과, 변형판(18)에서 변형된 광을 디스크(2)로 입사하는 대물 렌즈(object lens)(20)를 포함한다.The first light path S1 includes a first light source 10 that emits first light, a collimating lens 12 that converts the first light of the first light source 10 into parallel light, and a lens 12. A laser beam that passes through the first light of the first light source 10 and reflects the second light, and a second light that transmits the first light of the reflective mirror 14 and transmits the second light. The beam splitter (PBS) reflecting the light and the light diffracted in the light or the disk 2 of the beam splitter 16

A quarter wave plate 18 that deforms into and an object lens 20 that enters the light deformed by the deformation plate 18 into the disk 2 are included.

로 변형하는 변형판(32)과, 변형판(32)의 광을 평행광으로 바꾸는 렌즈(34)와, 렌즈(34)의 광을 디스크(2)에 소정의 각도로 입사하도록 하는 반사 미러(36)를 포함한다.The second light path S2 includes a second light source 30 that emits second light and a second light of the second light source 30.

The deformable plate 32 which deforms into the shape, the lens 34 which converts the light of the deformable plate 32 into parallel light, and the reflection mirror 36 which causes the light of the lens 34 to enter the disc 2 at a predetermined angle. It includes.

The first light source 10 is a red laser light source having a predetermined wavelength, for example, a wavelength of 650 nm, and generates laser light required for a digital data disk such as a DVD. The second light source 30 is a green laser light source having a predetermined wavelength, for example, a wavelength of 532 nm, and generates laser light required for a holographic ROM disk. Accordingly, the first light emitted from the first light source 10 has horizontal S-polarized light due to the red laser light property, and the second light emitted from the second light source 30 is perpendicular to the vertical P light due to the green laser light property. Has polarized light.

The first light detector PDIC1 44 is reflected by the reflective mirror 14 through the objective lens 20, the deformation plate 18, and the beam splitter PBS 16 of the first light path S1. Light is detected and the detection data is transmitted to the control unit 28. In this case, an imaging lens 38, a slit 40, and a lens 42 are configured between the reflection mirror 14 and the first light detector PDIC1 44.

The second light detector PDIC2 26 detects and detects the second light reflected by the beam splitter PBS 16 through the objective lens 20 and the deformation plate 18 of the first light path S1. The data is transmitted to the control unit 28. At this time, a collimating lens 22 and an astigmatism lens 24 are formed between the beam splitter PBS 16 and the second light detector PDIC2 26.

The control unit 28 horizontally shifts the position of the objective lens 20 located above the disk 2 of the first optical path S1 according to the data detected by the first light detector PDIC1 44. Performs focus servo control. Then, according to the data detected by the second light detector (PDIC2) 26, the position of the objective lens 20 on the disc 2 is moved horizontally or vertically to perform tracking and focus servo control of a digital data disc such as a DVD. .

2 is a diagram illustrating a holographic ROM disk structure and a reproduction process using the same according to an embodiment of the prior art. Referring to FIG. 2, the holographic ROM disk 2 used in the combo system of the holographic ROM and the digital data disk transmits the green laser light for the holographic (second light) and the red laser for the digital data disk such as a DVD. An optical mirror layer 202 of a material that reflects light (first light), a recording material layer 204 for recording holographic digital data, and a substrate layer 206 under the recording material layer 204 It is composed of

At this time, the total disk thickness is made about 1.2 mm like other optical disks, and the total thickness of the optical mirror layer 202 and the recording material layer 204 in the disk depends on the focal length of the objective lens 20 in the system. Is determined. Preferably, the optical mirror layer 202 and the recording material layer 204 have a thickness of about 0.6 mm in accordance with the focal length of the ordinary disk. When the distance of the disk surface from the objective lens 20 is about 1.4 mm, the distance from the objective lens 20 to the center of the recording material layer 204 is within the range of about 1.7 mm.

During reproduction, the holographic green laser light (second light) transmitted through the optical mirror layer 202 and the recording material layer 204 is equally incident at the reference light angle at the time of recording and is recorded in the recording material layer 204. The holographic data is diffracted and sent to the objective lens 20. Here, since the focal length between the objective lens 20 and the disk is limited and the size of the assembly on which the objective lens 20 is mounted has a range of about 7 mm from the center of the lens, overlapping recording, which is an advantage of the holographic disc ROM, is possible. The angle is limited. Accordingly, the incident angle α of the second holographic light has a range of 13.6 ° or less. Therefore, in the case of a holographic ROM disc, since the recording and reproduction require the same angle of incidence, the data capacity recorded on the holographic disc was limited to within the reference light range of 13.6 °.

For this purpose, the modified holographic ROM disk 2 as shown in FIG. 3 causes the recording material layer 204 to be lowered and the substrate layer 206 is embedded between the optical mirror layer 202 and the recording material layer 204. The structure was changed. That is, the disk structure is changed to include the substrate layer 206 below the optical mirror layer 202 and the recording material layer 204 below. The distance from the objective lens 20 to the center of the recording material layer 204 is about 2.3 mm, which is longer than the disk structure of FIG. The substrate layer 206 has a thickness of 0.6 mm in accordance with the focal length of the objective lens for the ordinary disk. Accordingly, the thickness of the recording material layer 204 can be increased to a thickness of 0.6 mm, which is the focal length of the ordinary disk, allowing more data recording.

The holographic green laser light (second light) is made incident on the recording material layer 204 on the lower surface of the holographic ROM disk 2 changed during reproduction at the reference light angle at the time of recording. The light passing through the recording material layer 204, the substrate layer 206, and the optical mirror 202 diffracts the holographic data light of the recording material layer 204 and enters the objective lens 20. At this time, the incident angle β of the second light incident on the lower surface of the disc 2 has a range of 18.2 ° or less, which is larger than that of FIG. 2. Therefore, in the holographic ROM disk, when the recording material layer 204 and the substrate layer 206 are exchanged with each other and the reproduction light is incident on the lower surface of the disk, the light is incident at an angle of incidence larger than that of FIG. Can increase data capacity.

However, there is a problem that the system structure for injecting reproduction light into the lower surface of the holographic ROM disk 2 is a complicated structure in which the objective lens covers the lower surface of the disk.

Therefore, in order to increase the data capacity of the holographic ROM disk used in the combo system, a new research and development is required to increase the overlap angle incident on the recording material layer, and a reproduction method for simplifying the system structure is required. It is.

SUMMARY OF THE INVENTION An object of the present invention is to provide a second optical mirror layer in which holographic light is reflected on a lower surface of a disk having a first optical mirror layer, a substrate layer, and a recording material layer in order to solve the above problems of the prior art. The present invention provides a holographic ROM disk that can increase the angle of light incident on the disk, thereby greatly increasing the data capacity recorded on the holographic disk.

Another object of the present invention is to provide a reproducing method using a holographic ROM disc capable of reproducing data by diffracting holographic data recorded on a recording material layer in the disc by reflecting light incident through the disc upper surface from the disc lower surface. It is.

In order to achieve the above object, the present invention provides a holographic ROM disk, comprising: a first optical mirror layer through which reproducing light for holographic transmission is transmitted, a substrate layer formed under the first optical mirror layer, and formed under the substrate layer, and A recording material layer on which the graphic data is recorded, and a second light mirror layer formed under the recording material layer and on which the holographic reproduction light is reflected.

In order to achieve the above another object, the present invention provides a method for reproducing data recorded on a holographic ROM disk, in which a first optical mirror layer, a substrate layer, a recording material layer, and a second optical mirror layer are sequentially formed. Incident holographic reproduction light on the upper surface of the holographic ROM disc, diffractive holographic data recorded on the recording material layer by light reflected through the second optical mirror layer of the disc, and transferring the holographic data to the objective lens; It includes.

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

4 is a diagram illustrating a holographic ROM disk structure and a reproduction process using the same according to the present invention.

4, the holographic ROM disk 300 according to the present invention includes a first optical mirror layer 302, a substrate layer 304, a recording material layer 306 And a second optical mirror layer 308. Unexplained reference numeral 110 denotes an objective lens and reference numeral 119 denotes a spindle motor for rotating the disk.

Here, the first light mirror layer 302 transmits the holographic green laser light (second light), which is a holographic reproduction light. The first light mirror layer 302 reflects red laser light (first light) for a digital data disk, such as a DVD, as other light, in addition to the second light, which is a holographic reproduction light.

The substrate layer 304 is embedded between the first light mirror layer 302 and the recording material layer 306.

The recording material layer 306 is embedded between the substrate layer 304 and the second optical mirror layer 308 and holographic data is recorded.

The second light mirror layer 308 is formed under the recording material layer 306 and reflects green laser light (second light), which is a reproduction light for holographic, and other light, for example, a red laser for a digital data disc. The light (first light) is transmitted as it is.

Therefore, the holographic ROM disk 300 according to the present invention has a first optical mirror layer 302, a substrate layer 304, a recording material layer 306, and a second optical mirror layer 308 from the top surface of the disk. This has a stacked structure sequentially.

Here, the distance from the objective lens 110 to the disk surface is about 1.4 mm and the substrate layer 304 has a thickness of 0.6 mm in accordance with the objective lens focal length in the general disk. And the radius of the assembly on which the objective lens 20 is mounted has a range of about 7 mm. Accordingly, the distance from the surface of the objective lens 110 to the bottom surface of the disk is about 2.9 mm at maximum, so that the total disk thickness can be increased from 1.2 mm of other optical disks, and the thickness of the recording material layer 306 is also increased more than 0.6 mm. More data can be recorded.

According to the holographic ROM disk structure according to the present invention, the second light (green laser light), which is a holographic reproduction light, is incident at the same angle as the reference light angle at the time of recording, and thus the first light mirror layer 302 to the recording material layer 306. ) Is transmitted to the surface of the second optical mirror layer 308. The second light reflected through the second light mirror layer 308 diffracts the holographic data recorded in the recording material layer 306 and is sent to the objective lens 110.

Since the second light, which is a holographic reproduction light incident on the disk according to the present invention, is transmitted to the lower surface of the recording material layer 306, that is, the surface of the second light mirror layer 308, the incident angle γ of the second light is 22.5. It has a range of less than or equal to Therefore, in the case of the holographic ROM disc, since the recording and playback require the same angle of incidence, the data capacity recorded on the holographic disc can be superimposed within the range of 22.5 ° or less, thereby increasing the data storage capacity significantly. .

Meanwhile, a process of servo control using data recorded on the holographic ROM disk in the combo system of the holographic ROM and the digital data disk by the holographic ROM disk structure according to the present invention will be described with reference to FIG. 5. 5 is a block diagram schematically illustrating an apparatus for focusing and tracking servo control of a combo system for playing a holographic ROM disk according to the present invention.

Referring to FIG. 5, the combo system with the servo control device is adapted to cause the first light from the first light source 100, which is a red laser light source having a wavelength of 650 nm for the digital data disc, to enter the surface of the holographic disc 300. A second light from the second light source 120, which is a green laser light source having a wavelength of 532 nm for the holographic ROM disk, to enter the surface of the disk 300 Light path S2.

로 변형하는 변형판(108)과, 변형판(108)에서 변형된 광을 디스크(300)로 입사하는 대물 렌즈(object lens)(110)를 포함한다.In the first optical path S1, a first light source 100 emitting a first light of a red laser for a digital data disc and a collimating lens converting the first light of the first light source 100 into parallel light. 102, a reflection line mirror 104 that transmits the first light of the first light source 100 that has passed through the lens 102 and reflects the second light, and the second reflection mirror 104. The beam splitter (PBS) 106 that transmits one light and reflects the second light, and the light diffracted by the light of the beam splitter 106 or the disk 300

And a deformable plate 108 that deforms into the deformed plate 108, and an object lens 110 that enters the light deformed by the deformable plate 108 into the disk 300.

로 변형하는 변형판(122)과, 변형판(122)의 광을 평행광으로 바꾸는 렌즈(124)와, 렌즈(124)의 광을 디스크(300)에 소정의 각도로 입사하도록 하는 반사 미러(126)를 포함한다.In the second light path S2, a second light source 120 emitting a second light of the green laser for the holographic ROM disk, and a second light of the second light source 120 are provided.

The deformable plate 122 which deforms into a light source, the lens 124 which converts the light of the deformable plate 122 into parallel light, and the reflection mirror 126 which causes the light of the lens 124 to enter the disk 300 at a predetermined angle. It includes.

The servo control apparatus of the combo system to which the present invention is applied includes a first light detector (PDIC1) 134 for detecting the first light diffracted by the disc 300 and a second light diffracted by the disc 300. A second light detector (PDIC2) 116 is included. In this case, an imaging lens 128, a slit 130, and a lens 132 are formed between the reflective mirror 104 and the first light detector PDIC1 134. A collimating lens 112 and an astigmatism lens 114 are configured between the beam splitter PBS 106 and the second light detector PDIC2 116.

The servo control apparatus of the combo system using the holographic ROM disk according to the present invention configured as described above operates as follows.

The second light of the green laser for the holographic ROM disk generated at the second light source 120 enters the upper surface of the disk at an angle of 22.5 ° or less through the deformation plate 122, the lens 124 and the reflection mirror 126. Then, the incident second light is transmitted to the surface of the second light mirror layer 308 through the first light mirror layer 302 to the recording material layer 306 in the disk 300. The second light reflected by the second light mirror layer 308 then diffracts the holographic data recorded in the recording material layer 306 and is sent to the objective lens 110.

Light of the objective lens 110 is incident on and reflected through the reflecting plate 104 through the deformation plate 108 and the beam splitter (PBS) 106 to reflect the lens 128, the slit 130, and the lens 132. The first light detector PDPD1 is transmitted to the first light detector 134.

The optical signal detected by the first light detector (PDIC1) 134 is transmitted to the controller 118, and the controller 118 is located above the disk 300 of the first optical path S1 according to the detected optical data. The focus servo control of the holographic ROM disk is performed by horizontally shifting the position of the objective lens 110.

Next, a process of reproducing data using the holographic ROM disk according to the present invention will be described with reference to FIG. 6. 6 is a view for explaining a playback method using a holographic ROM disk according to the present invention.

Referring to FIG. 6, the combo system using the holographic ROM disc according to the present invention configured as described above reproduces data recorded on the disc as follows.

The second light of the green laser for the holographic ROM disk generated in the second light source 120 is angled 22.5 ° or less to the upper surface of the disk through the deformation plate 122, the lens 124 and the reflection mirror 126. Incident light is transmitted through the first light mirror layer 302 to the recording material layer 306 in the disc to the surface of the second light mirror layer 308. The second light reflected through the second light mirror layer 308 then diffracts the holographic data recorded in the recording material layer 306 and is sent to the objective lens 140.

The light of the objective lens 140 is transmitted to the photodetector (PDIC) 146 through the slit 142 and the lens 144, and the light detected by the photodetector (PDIC) 146, although not shown in the drawing, is a CCD. It is output as holographic data through an image capturing device such as (Charge Couple Device).

As described above, the present invention adds a second optical mirror layer on which the holographic light is reflected to the lower surface of the disk sequentially having the first optical mirror layer, the substrate layer, and the recording material layer. By increasing the angle to a range of 22.5 ° or less, the data capacity recorded on the holographic disc can be greatly increased.

Since the combo system using the holographic ROM disk of the present invention has a structure in which the holographic light is incident on the upper surface of the disk, the objective lens does not need to be changed to a complicated structure covering the lower surface of the disk as shown in FIG. 3. .

On the other hand, the present invention is not limited to the above-described embodiment, various modifications are possible by those skilled in the art within the spirit and scope of the present invention described in the claims to be described later.

Claims (4)

In the holographic ROM disc, A first optical mirror layer through which the holographic reproduction light is transmitted; A substrate layer formed under the first optical mirror layer; A recording material layer formed under the substrate layer and recording the holographic data; A second optical mirror layer formed under the recording material layer and reflecting the holographic reproduction light; Holographic ROM disk containing. The method of claim 1, And the first optical mirror layer reflects light other than the holographic reproduction light. The method of claim 1, And the second optical mirror layer transmits light other than the holographic reproduction light. A method for reproducing data recorded on a holographic ROM disc, Injecting said holographic reproducing light into the upper surface of the holographic ROM disk on which a first optical mirror layer, a substrate layer, a recording material layer, and a second optical mirror layer are sequentially formed; Diffracting the holographic data recorded in the recording material layer by the light reflected through the second optical mirror layer of the disc and transferring it to the objective lens Playback method using a holographic ROM disk comprising a.

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