KR20090085354A - Method and apparatus for recording/reproducing the data - Google Patents

Abstract

A data recording/reproducing method and apparatus are provided to ensure stable data reproduction by extending the range of a physical margin for physical error and correcting a physical error within the physical margin. A data recording/reproducing apparatus comprises a first beam output part, a second beam output part, and an optical converter(12). The first beam output part irradiates first light beam to a recording medium in recording/reproducing. The second beam output part irradiates second light beam including data to the recording medium in recording. The optical converter converts the wavefront of one or more beam of the first and second light beam into a curved plane along an axis parallel to the radial direction of the recording medium.

Description

Data recording / playback method and recording / playback device {Method and Apparatus for recording / reproducing the data}

The present invention relates to a data recording / reproducing method and a recording / reproducing apparatus. In particular, it relates to a data recording / reproducing method and a recording / reproducing apparatus using holography.

TECHNICAL FIELD The present invention relates to data recording / reproducing, and more particularly, to a method and apparatus for recording / reproducing data on a recording medium using holography.

Background Art [0002] An apparatus for recording and reproducing information on a recording medium such as a compact disc (CD) or digital versatile disk (DVD), which is currently spreading, records information on a tomographic recording surface of a recording medium or reproduces information recorded on a tomographic recording surface. The storage capacity can be increased by stacking the recording / reproducing surfaces of the recording medium. However, since the recording / reproducing surface that can be stacked on a single recording medium is about four layers, the storage capacity increases.

Due to such a problem of storage capacity limitation, recently, holographic storage technology has attracted attention. Holography is a technology that can reproduce an optical signal as it is, and stores an interference pattern generated by a signal light having information and a reference light irradiated from an angle different from the signal light on a recording medium or by using diffraction of the stored interference pattern. It is a technology that can reproduce information. By using the holographic storage technology, since interference patterns can be superimposed in three-dimensional (spatial) directions in the thickness direction of the recording medium, the storage capacity can be dramatically increased. In other words, when information is recorded while changing the incident angle, phase, wavelength, and the like of the reference light, it is possible to record several pieces of holography information at a constant capacity. Therefore, it is possible to implement a super capacity recording medium. In addition, since the signal light and the reference light can be irradiated to the recording medium using the optical splitter and the single objective lens, the data recording / reproducing apparatus can be miniaturized.

In the case of a reproducing apparatus for reproducing data recorded using holography technology, the recording medium is rotated at an angle and stopped to reflect data of tens or hundreds of pages recorded in a predetermined area of the recording medium, and then reflected from the recording medium. The process of photographing reproduction light has to be repeated dozens of times. As described above, when a recording / reproducing method uses a holography technique different from other recording / reproducing methods, an optical system or a recording / reproducing method suitable for this is required.

In order to read out the information recorded on the recording medium, accurate information can be obtained when the same wavefront as the wavefront of the light beam stored during recording is made. The allowable range according to the physical error with respect to the information is indicated using the term physical margin. When the playback exceeds the range of the physical margin, the playback is impossible or unstable and unclear information is obtained even if the playback is possible. Therefore, when a physical error occurs in the recording medium, there is a need to induce a method of expanding the range of physical margins and correcting the generated errors to derive an error range within the range of physical margins.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and the data recording / reproducing method and recording method which can extend the range of the physical margin for the error occurring during reproduction, and induce the within the range of the physical margin by compensating for the generated error. It relates to a playback device.

SUMMARY OF THE INVENTION The present invention achieves the above object, and includes a first optical output unit for irradiating a recording medium with a first light beam at the time of recording / reproducing and a second optical beam for irradiating a recording medium with a second light beam including data at the time of recording. Provided is a data recording / reproducing apparatus including an optical output unit and an optical conversion unit for converting a wavefront of at least one of the first and second light beams.

In addition, the optical conversion unit provides a data recording / reproducing apparatus, wherein the wavefront of the light beam is converted to have a curved surface along an axis parallel to the radial direction of the irradiated recording medium.

In addition, the first light beam provides a data recording / reproducing apparatus, characterized in that it is a reference beam which causes interference with the second light beam during recording and reads out an image recorded on the recording medium during reproduction.

In addition, the light conversion unit provides a data recording / reproducing apparatus, characterized in that the cylindrical lens (cylindrical lens).

In addition, the optical conversion unit provides a data recording / reproducing apparatus, characterized in that the first and second light generating unit and the recording medium.

The present invention also provides a data recording / reproducing apparatus, further comprising a first correcting unit for controlling and adjusting angles of the first and second light generating units to correct an inclination of the recording medium in a radial direction.

The present invention also provides a data recording / reproducing apparatus, further comprising a second correction unit for correcting a tilt in a tangential direction of a recording medium.

The method may further include irradiating a recording medium with a first light beam during recording / reproducing, irradiating a recording medium with a second light beam including data during recording, and converting a wavefront of at least one of the first and second light beams. It provides a data recording / reproducing method comprising the step of.

The apparatus may further include a first optical output unit for outputting a cylindrical wave during recording / reproducing, a second optical output unit for outputting a light beam including data during recording, and a control unit for determining and correcting warpage in a radial direction of the recording medium. Provided is a data recording / reproducing apparatus.

The present invention also provides a data recording / reproducing method comprising outputting a cylindrical wave during recording / reproducing, outputting a light beam including data during recording, and determining and correcting warping in a radial direction of the recording medium. .

The data recording / reproducing method and the recording / reproducing apparatus according to the present invention have the following effects. The data recording / reproducing method and the recording / reproducing apparatus according to the present invention have advantages in that stable data reproduction is possible by expanding a range of physical margins for physical errors of a recording medium and compensating the generated physical errors within a range of physical margins. .

Hereinafter, exemplary embodiments of a data recording / reproducing method and a recording / reproducing apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

In addition, the terminology used in the present invention was selected as a general term widely used as possible, but in some cases, the term is arbitrarily selected by the applicant, in which case the meaning is described in detail in the corresponding description of the invention, It is to be understood that the present invention is to be understood as the meaning of terms rather than names.

In this regard, in the present invention, "recording medium" means any medium on which data is recorded or is recordable, and encompasses all mediums regardless of a recording method such as a disc, a magnetic tape, and the like. Hereinafter, the present invention will be described by using a disk, in particular, a "holography recording medium" as a recording medium for convenience of explanation, but it will be apparent that the technical concept of the present invention is equally applicable to other recording media.

1 is an embodiment of a recording apparatus and / or a playback apparatus according to the present invention. In FIG. 1, general components are omitted and only components necessary to describe the technical gist of the present invention are illustrated. As shown in FIG. 1, the data recording / reproducing apparatus according to the present invention includes a light source unit 11, first and second light splitters 13 and 16, a light control unit 14, a light modulator 15, and a light source. The converter 12 includes a memory 17, an image sensor 18, and a controller 20.

The light source unit 11 is composed of a gas laser, a solid state laser, a semiconductor laser, a semiconductor diode, or the like which generates light having a very high coherence, for example, a laser beam. In addition, a lens that collects the light output from the light source unit 11 so as not to be dispersed, for example, a collimator lens may be disposed at the output end side.

The first light splitter 13 receives the light output from the light source 11 and divides the light into a signal light and a reference light. The first light splitter 13 may be composed of one or more transparent substrates and one or more grating layers diffracting light, or may be composed of mirrors that reflect a part of the light and pass the rest. A part of the light passing through the first light splitter 13 is incident to the second light splitter 16, and a part of the light enters the light modulator 15.

The light modulator 15 generates signal light including data using the light output from the first light splitter 13 under the control of the controller. For example, the light modulator 15 may include binary data represented by black and white dots in the signal light. In this case, for convenience, the white dot may be referred to as "on" and the black dot may be referred to as "off." Or you can name it the other way around.

In addition, the signal light may include data, in which a series of data including user data to be recorded by a user may be recorded. In addition to the user data, data to be recorded includes control information and a mark for indicating an area of data.

In addition, the data generated from the light modulator 15 may be data having a two-dimensional image. Such data may be referred to as "data images" for convenience. The data image can be represented using binary dots of on (0n) / off (off) as described above. In addition, the light modulator 15 may represent the data image in pixel units or pixel block units to represent each pixel of the data image as binary dots, and may be controlled by the controller.

The signal beam is irradiated to the recording medium 100 and the recording medium is irradiated to the reference beam. The reference beam is a beam incident from the first light splitter is incident to the second light splitter, and the beam from the second light splitter passes through the light control unit 14 and is incident to the recording medium through the light converting unit 12. to be.

The reference beam may be named as the reference beam. The reference beam refers to a beam that interferes with the signal beam when data is recorded on the recording medium 100. In addition, the reference beam refers to a beam used when reading data from the recording medium. However, as shown in FIG. 1, the reference beam and the reference beam may be used as coming from the same light source. The light adjusting unit 14 adjusts the incident angle, direction, wavelength, phase, and the like of the second light under the control of the controller to inject the second light into the recording medium 100. The light conversion unit 12 serves to convert the wavefront of the light beam passing through the light control unit 14. More preferably, it serves to convert the wavefront of the light beam into a cylindrical wave. This will be described in detail later.

Different interference fringes are recorded on the recording medium in accordance with the phase and wavelength of the reference beam. Therefore, it is possible to repeatedly record in the same area of the recording medium by varying the phase or wavelength of the reference beam. This characteristic can be used to increase the capacity of the holographic recording medium. That is, a plurality of data images can be recorded in one area.

As a component including the above-described light source, the second light splitter, and the light control unit, a component named "first light output unit" may be used in the present invention. In addition, a component named "second light output unit" may be used in the present invention as a component including all of the above-described light sources, characteristics of the first light splitter and the light modulator.

In addition, when recording the recording medium, both the first light output unit and the second light output unit should be used. On the other hand, when the recording medium is reproduced, even if only the reference beam is used, an image recorded on the recording medium can be read. Therefore, according to the present invention, only the first optical output unit may be used when the recording medium is reproduced.

At the time of reproduction, information can be read by irradiating the recording medium with light of the same phase and wavelength as used at the time of recording. Therefore, the phase, the wavelength of the light used at the time of recording, the angle of incidence of the light control unit, etc. can be recorded or stored in the memory 17 and used at the time of reproduction.

In addition, the memory 17 can store distortion characteristics and the like according to the recording apparatus. In addition, the memory may temporarily store the position of the reference pattern to be inserted into the data image and then record it on the recording medium. In addition, the memory 17 may record stored data on a recording medium or may be used for recording / reproducing under the control of a controller. In addition, the memory 17 may store data to be recorded on the recording medium, and may store information other than user data among data recorded on the recording medium.

The image sensor 18 may be configured as a photodetector such as a charge-coupled device (CCD) or a CMOS. It may also be composed of a plurality of photodetecting elements. For example, it may be composed of a plurality of photodetectors capable of providing a resolution such as 300 * 200, 1000 * 800. The image sensor 18 passes through the recording medium or receives the light reflected from the recording medium 100, and captures / reads a data image included in the received light. As an example, the image sensor shown in FIG. 1 receives light passing through a recording medium. Alternatively, phase conjugate signal light (corresponding to a data image) generated in a direction reflected from the recording medium may be received. In addition, the image sensor may be named under the light receiving unit.

The controller 20 may read data recorded in the memory 17 or the recording medium, or generate new data and provide the data to the optical modulator 15. In addition, the controller 20 controls the optical modulator 15 to generate a two-dimensional bitmap in which data read from the memory is represented by black and white dots. In addition, the control unit controls the light adjusting unit 14 to adjust the intensity, incident angle, phase, wavelength, etc. of the second light causing interference with the first light. As described above, the light adjusting unit 14 may be controlled to store a plurality of data images (data pages) in the same area of the recording medium 100. In addition, the light adjusting unit 14 may be controlled to enter a beam having the same condition as that of recording, thereby reproducing the data image stored in the recording medium. In addition, the control unit 20 can detect the light intensity (luminance) in each of the two-dimensional directions of the data read by the image sensor 18, that is, in the x direction (horizontal) and the y direction (vertical).

In addition, the controller 20 can correct the data image. As an example of a method of correcting a data image, there is a method of including a reference mark in which the position and pattern information is known in advance in the data image. When reproducing the data image including the reference mark, the controller 20 may compensate for the movement and distortion in the data image by measuring the movement amount or the distortion amount of the reference mark. In addition, when the position of the reference pattern is incorrectly detected, the position of the read reference pattern may be compensated and reflected in the data image compensation.

In addition, the controller 20 may recognize whether a physical error occurs in the recording medium and compensate the physical error by adjusting the first corrector and the second corrector.

As the recording medium 100, a recording medium in the form of a disk or a volume may be used.

First, in the present invention, a general description of the radial direction and the tangential direction is given. 5 is a diagram in which the radial direction and the tangential direction can be known in detail. The radial direction means a direction perpendicular to the rotation direction with respect to the rotation direction of the recording medium. The tangential direction means a direction parallel to the rotation direction with respect to the rotation direction of the recording medium.

FIG. 2A illustrates a light beam of a flat polarized wave irradiated onto a recording medium when the light conversion unit 12 does not exist, and FIG. 2B illustrates a cylindrical lens when the light conversion unit 12 according to the present invention is present. A diagram showing a light beam of a cylindrical wave that passes through and is irradiated onto a recording medium. 2B shows a light beam having a curved surface along an axis parallel to the radial direction of the recording medium.

In the case where data is recorded by injecting a light beam having a flat surface, an error occurs in the wavefront of the light beam incident on the recording medium during reproduction, because the data image must be reproduced by injecting a beam having the same conditions as in recording. This makes it difficult to reproduce data images. In other words, even if a small physical error occurs due to a narrow physical margin, the reproduction becomes difficult.

This can be more clearly seen in FIGS. 3A and 3B. When the wavefront recorded on the recording medium is flat, it can be seen that data reproduction is difficult due to the wavefront mismatch even if a slight physical error occurs in the recording medium or the like.

On the other hand, when the shape of the wavefront recorded on the recording medium is incident to the cylindrical beam of light, as shown in FIG. 4B, even if a slight physical error occurs in the recording medium later, the degree of matching of the wavefront is higher than the plane wave due to the curvature of the wavefront. More stable data reproduction is possible.

The cylindrical wavefront may be generated by passing the cylindrical lens as mentioned above. The beam passing through the cylindrical lens has an advantageous effect in reproducing data even when a physical error occurs due to the cylindrical lens surface. More specifically, the wavefront has a curved surface about an axis parallel to the radial direction of the recording medium.

In addition to the above mentioned physical margins, the physical error itself can also be corrected. However, this corresponds to an embodiment, and the method of enlarging the physical margin and the method of correcting the physical error may be performed simultaneously or separately, and one of ordinary skill in the art may freely select or easily change it.

(Example 1)

FIG. 6 is a diagram showing a method of correcting a physical error when the recording / reproducing direction of the recording medium is in a rotational direction, that is, in a concentric direction. After the recording medium is loaded in the recording / reproducing direction as described above, the controller 20 determines whether the recording medium is inclined. In the method of determining whether the control unit 20 is inclined, for example, the control unit rotates the light generating unit in a radial direction or a tangential direction to control light to be irradiated onto the recording medium. While rotating the light generation unit, the gradient information is detected by comparing the brightnesses of the areas designated by the user in the data page emitted through the image sensor unit. Through this, it is determined whether the recording medium of the recording medium is inclined. This corresponds to an example of the tilt of the recording medium, and various tilt determination methods may be possible. The present invention is not limited to the above-described method, and those skilled in the art will be able to illustrate various methods of detecting the tilt.

Subsequently, when it is determined whether the inclination corresponds to the radial direction, as shown in FIG. 7, the degree of inclination is adjusted by changing the angle of the first and / or second light generating unit by adjusting the first correction unit as shown in FIG. 7. The distance between the first and / or second light generating section and the recording medium is kept constant as much as possible.

In addition, when the inclination corresponds to the tangential direction, as shown in FIG. 8, the lower axis of the recording medium is rotated by adjusting the second compensator so that the optical axis of the light generating part and the rotation center axis of the recording medium are parallel to each other.

(Example 2)

FIG. 9 is a diagram showing an embodiment in the case where the recording / reproducing direction of the recording medium is made perpendicular to the rotational direction, that is, the radial direction of the recording medium.

If the warp or tilt error of the recording medium is generated through the detection method of various methods described in Example 1, if the tilt of the recording medium corresponds to the radial direction as shown in FIG. The inclination is corrected by changing the angle of the first and / or second light generating unit.

In addition, when the inclination corresponds to the tangential direction, the recording medium is adjusted such that the optical axis of the first and / or second light generating unit and the rotation center axis of the recording medium are parallel as shown in FIG. 11. Rotate the lower axis of the

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

1 is an embodiment of a data recording / reproducing apparatus according to the present invention.

2A is a view showing a wavefront of a light beam according to the prior art.

Figure 2b is a view showing the wavefront of the light beam according to the present invention.

3A and 3B are diagrams showing the degree of securing physical margin according to incidence of plane waves.

4a and 4b are diagrams showing the degree of securing the physical margin according to the incidence of the cylindrical wave according to the present invention.

5 is a diagram relating to a radial direction and a tangential direction.

FIG. 6 is a diagram illustrating a case in which the recording / reproducing direction of the recording medium is in the rotational direction, that is, in the direction of concentric circles.

7 is a diagram illustrating a method of correcting a physical error in a radial direction according to an embodiment of the present invention.

8 is a diagram illustrating a method of correcting a physical error in a tangential direction according to an embodiment of the present invention.

9 is a diagram illustrating a case in which the recording / reproducing direction of the recording medium is in a direction perpendicular to the rotation direction, that is, in a radial direction.

10 is a diagram illustrating a method of correcting a physical error in a radial direction according to another embodiment of the present invention.

11 is a diagram illustrating a method of correcting a physical error in a tangential direction according to another embodiment of the present invention.

Claims (17)

A first light output unit for irradiating the recording medium with the first light beam at the time of recording / reproducing; A second light output unit for irradiating the recording medium with a second light beam including data at the time of recording; And And a light converter for converting a wavefront of at least one of the first and second light beams. The method of claim 1, And the optical conversion unit converts the wavefront of the light beam to have a curved surface along an axis parallel to the radial direction of the recording medium irradiated. The method of claim 1, And the first light beam is a reference beam which causes interference with the second light beam during recording and reads out an image recorded on the recording medium during reproduction. The method of claim 1, And the optical conversion unit is a cylindrical lens. The method of claim 1, And the optical conversion unit is between the first and second light generating units and the recording medium. The method of claim 1, And a first correction unit for controlling and adjusting angles of the first and second light output units to correct an inclination of the recording medium in a radial direction. The method of claim 1, And a second correction unit for correcting the inclination of the recording medium in the tangential direction. Irradiating a recording medium with the first light beam upon recording / reproducing; Irradiating a recording medium with a second light beam containing data at the time of recording; And Converting a wavefront of at least one of the first and second light beams. The method of claim 8, And the optical conversion unit converts the wavefront of the light beam to have a curved surface along an axis parallel to the radial direction of the recording medium irradiated. The method of claim 8, And the first light beam is a reference beam which interferes with the second light beam during recording and reads out an image recorded on the recording medium during reproduction. The method of claim 8, And the optical conversion unit is a cylindrical lens. The method of claim 1, And controlling and adjusting the angles of the first and second light generators to correct the inclination of the recording medium in the radial direction. The method of claim 1, And correcting the inclination of the recording medium in a tangential direction. A first optical output unit for outputting a cylindrical logical wave during recording / reproducing; A second light output unit for outputting a light beam including data during recording; And A data recording / reproducing apparatus, comprising a control unit for determining the warp in the radial direction of the recording medium and correcting it. The method of claim 14, And the controller determines the warpage in the tangential direction of the recording medium and corrects the warp. Outputting a cylindrical wave during recording / reproducing; Outputting a light beam comprising data at the time of recording; And And determining the deflection in the radial direction of the recording medium and correcting it. The method of claim 16, And determining the deflection in the tangential direction of the recording medium and correcting it.

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