KR20100006441A - Method and apparatus for compensating tilt of recording medium - Google Patents

Method and apparatus for compensating tilt of recording medium Download PDF

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Publication number
KR20100006441A
KR20100006441A KR1020080066665A KR20080066665A KR20100006441A KR 20100006441 A KR20100006441 A KR 20100006441A KR 1020080066665 A KR1020080066665 A KR 1020080066665A KR 20080066665 A KR20080066665 A KR 20080066665A KR 20100006441 A KR20100006441 A KR 20100006441A
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KR
South Korea
Prior art keywords
tilt
recording medium
detector
light
amount
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KR1020080066665A
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Korean (ko)
Inventor
하상우
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엘지전자 주식회사
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Priority to KR1020080066665A priority Critical patent/KR20100006441A/en
Publication of KR20100006441A publication Critical patent/KR20100006441A/en

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    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/004—Recording, reproducing or erasing methods; Read, write or erase circuits therefor
    • G11B7/0065—Recording, reproducing or erasing by using optical interference patterns, e.g. holograms
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/007—Arrangement of the information on the record carrier, e.g. form of tracks, actual track shape, e.g. wobbled, or cross-section, e.g. v-shaped; Sequential information structures, e.g. sectoring or header formats within a track
    • G11B7/00772—Arrangement of the information on the record carrier, e.g. form of tracks, actual track shape, e.g. wobbled, or cross-section, e.g. v-shaped; Sequential information structures, e.g. sectoring or header formats within a track on record carriers storing information in the form of optical interference patterns, e.g. holograms
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/08—Disposition or mounting of heads or light sources relatively to record carriers
    • G11B7/09—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
    • G11B7/095—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following specially adapted for discs, e.g. for compensation of eccentricity or wobble
    • G11B7/0956—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following specially adapted for discs, e.g. for compensation of eccentricity or wobble to compensate for tilt, skew, warp or inclination of the disc, i.e. maintain the optical axis at right angles to the disc
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
    • G11B7/13—Optical detectors therefor

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  • Optical Recording Or Reproduction (AREA)
  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)

Abstract

The tilt compensation method of the recording medium according to the present invention comprises the steps of obtaining a data image reproduced from the recording medium, measuring the light amount of the data image, detecting the tilt of the recording medium based on the measured light amount and Compensating for the detected tilt.

Description

Tilt Compensation Method and Compensation Device for Recording Media {METHOD AND APPARATUS FOR COMPENSATING TILT OF RECORDING MEDIUM}

The present invention relates to a tilt compensation method and a compensation device of a recording medium, and more particularly to a method and a device for compensating for a tilt of a recording medium that can occur in a holographic storage device. will be.

Background Art An apparatus for recording and reproducing information on a recording medium such as a compact disc (CD) or a digital versatile disc (DVD), which is currently prevalent, records information on a tomographic recording surface of a recording medium or reproduces information recorded on a tomographic recording surface. Although the storage capacity can be increased by stacking the recording and reproducing surfaces of the recording medium as described above, since there are about four recording and reproducing surfaces that can be stacked on a single recording medium, there is a limit in increasing the storage capacity.

As such, data storage technology using holography has recently attracted attention due to the limitation of the storage capacity of the existing recording medium. Holography is a technology that can reproduce an optical signal as it is, and stores an interference pattern made by a signal light having information and a reference light scanned at a different angle from the signal light on a recording medium, or by using diffraction of the stored interference pattern. It is a skill to play.

Using this holography storage technology, since three-dimensional interference patterns can be recorded in the thickness direction of the recording medium, the data storage capacity can be dramatically increased. In particular, it is possible to record a plurality of holographic information at a constant capacity by using a multiplexing technique that allows the information to be superimposed on the same area by changing the incident angle, phase, wavelength, etc. of the reference light. It is possible.

As described above, due to the characteristics of the holographic data storage device which stores the two-dimensional data by overlapping the reference light and the signal light and storing the diffraction pattern, the incident angle of the reference light when the data is stored must be kept the same even during reproduction. Data can be restored accurately.

However, the tilt of the recording medium may occur in the holographic storage device due to detachment of the recording medium or an error occurring during the manufacture of the recording medium and the recording of data. If the tilt of the recording medium cannot be compensated for, the incident angle of the reference light is changed during data storage and playback, and thus the quality of the reproduced data is significantly degraded. Therefore, there is a need for a method for detecting and effectively removing tilt errors that may occur in a recording medium during data reproduction.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to detect and effectively eliminate a tilt error of a recording medium which may occur in a holographic storage device.

In order to solve the above problems, the tilt compensation method of the recording medium according to the present invention comprises the steps of obtaining a data image reproduced from the recording medium, measuring the light amount of the data image, the tilt of the recording medium based on the measured light amount Detecting and compensating for the detected tilt.

Measuring the amount of light may include setting a plurality of detection positions in the data image and measuring a reduction in partial amount of light at each of the plurality of detection positions.

In the step of setting the plurality of detection positions, the plurality of detection positions can be set apart from each other.

A plurality of detection positions can be set to be symmetrical with each other in a tangential direction and a radial direction of the recording medium.

The plurality of detection positions are a first detector set at an arbitrary position of the data image, a second detector set at a position symmetrically symmetric with the first detector, and a third set at a position symmetrically radially oriented with the first detector. And a fourth detector set at a position symmetric to the detector and the third detector in a tangential direction.

The detecting of the tilt may include detecting the tilt in the tangential direction and the tilt in the radial direction based on the amount of light measured by the first to fourth detectors.

Compensating the tilt may include compensating for the detected radial tilt and the tangential tilt.

On the other hand, the tilt compensation device of the recording medium according to the present invention obtains the data image reproduced from the recording medium, and detects the tilt of the recording medium on the basis of an image detection unit for measuring the amount of light of the data image, based on the amount of light measured by the image detection unit And a tilt compensator for compensating the tilt of the recording medium under the control of the tilt compensator and the tilt compensator.

The image detector may measure a partial decrease in the amount of light at each of the plurality of detection positions set in the data image.

The plurality of detection positions may be set apart from each other.

The plurality of detection positions may be set to be symmetric with each other in the tangential direction and the radial direction of the recording medium.

The tilt controller may detect the tilt in the tangential direction and the tilt in the radial direction based on the amount of light measured by the first to fourth detectors.

The tilt compensator may compensate for the radial tilt and the tangential tilt.

By the tilt compensation method and the compensation device according to the present invention it is possible to obtain an improved reproduction quality and to increase the reliability of the system. In addition, it is possible to obtain the effect of performing the tilt compensation of the recording medium more precise and rapid.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention.

The terminology used in the present invention was selected as a general term that is widely used at present, but in some cases, the term is arbitrarily selected by the applicant, and in this case, the meaning of the term is described in detail in the description of the present invention. The present invention should be understood as meanings other than terms.

1 is a schematic diagram showing an example of a hologram recording and reproducing apparatus to which the tilt compensation method and apparatus according to the embodiment of the present invention are applicable.

As shown in the drawing, the recording and reproducing apparatus uses data reflected from the recording unit 100 and an optical unit 200 including components for recording or reproducing data by irradiating light onto the recording medium 100. And a reproducing unit 300 including components for reproducing or performing tilt control.

The optical unit 200 includes a light source 210, a beam splitter 220, a modulator 240, and first and second mirrors 230 and 250.

The light source 210 may be configured as a device that generates very high coherence light such as a laser beam. For example, the light source 210 may be a gas laser, a solid state laser, a semiconductor laser, or a semiconductor diode. In this case, the light source 210 may generate laser light having a wavelength of 407 nm, for example.

The light splitter 220 splits the light output from the light source 210 into signal light and reference light. The light splitter 220 may be composed of one or more transparent substrates and one or more grating layers diffracting the light, or may be configured of a mirror that reflects a part of the light and passes the rest.

When recording data, the first mirror 230 receives the signal light from the optical splitter 220 and transmits the signal light to the optical modulator 240.

The optical modulator 240 includes a data pattern in the signal light and outputs the data pattern. For example, the optical modulator 240 includes binary data represented by a black and white dot pattern in the signal light output from the optical splitter 220. The signal light output from the optical modulator 240 is irradiated to the recording medium 100. In this case, the light modulator 240 may be a spatial light modulator (SLM).

The second mirror 250 receives the reference light from the light splitter 220 and adjusts the incident angle, direction, and the like of the reference light to irradiate the recording medium 100. At this time, the angle of the reference light may be multiplexed in order to record or reproduce data. That is, the data recording and reproducing apparatus according to the present embodiment records data while continuously changing the incident angle of the reference light irradiated to a predetermined region of the recording medium 100. In this way, hundreds to thousands of holograms composed of page units of binary data can be stored in the same place.

By recording or reproducing a lot of data on a recording medium 100 in units of pages, data can be recorded or reproduced with high storage density. This is because data included in the signal light is recorded on the recording medium 100 in different interference patterns according to the incident angle of the reference light. The angle of incidence of the reference light irradiated for reproducing the data recorded by this method must match the angle of incidence at the time of recording.

When data is recorded or reproduced, the reference light irradiated to the recording medium 100 by the second mirror 250 is diffracted by the interference fringe of the data recorded on the recording medium 100.

The configuration of the optical unit 200 described above is for illustrating the present invention, the present invention is not limited thereto, and various additional components may be added as necessary.

The playback unit 300 for reproducing data and compensating for tilt of the recording medium includes an image detector 310, a tilt controller 320, a tilt compensator 330, and an image processor 340.

The image detector 310 detects the holographic data image. Accordingly, the image detector 310 restores the reproduction output transmitted from the recording medium 100 to the original data, that is, the electrical signal, and the reproduced reproduction signal is reproduced and output through the image processor 340.

In addition, the image detector 310 measures a partial amount of light of the data image to detect the tilt and transmits it to the tilt controller 320. As shown in FIG. 1, the tilt of the recording medium 100 may include tangential and radial components of the recording medium 100.

2 shows examples of various data images in which tilt occurs. As shown in FIG. 2, a partial change in the amount of light appears in the data image by the tangential and radial tilt components.

The image detector 310 may set a plurality of detection positions in the reproduced data image and detect light amounts of the portion. 3 is a schematic diagram illustrating a detection position. The detection positions may be set to be spaced apart from each other so as to be symmetrical with each other in the tangential direction and the radial direction of the recording medium 100.

As shown in FIG. 3, the plurality of detection positions include the first detection unit A, the second detection unit B, and the first detection unit A, which are set at positions symmetric to the first detection unit A in a tangential direction. And a third detector C set at a position symmetrically in the radial direction and a fourth detector D set at a position symmetrically symmetric with the third detector C. FIG. However, this is for illustrating the present invention, and each detection position may be set by varying the number and position.

As the image detector 310, a CMOS image sensor or a CCD image sensor may be used.

The tilt controller 320 detects the tilt of the recording medium 100 using the partial light amount of the data image measured by the image detector 310, and controls the tilt compensation. That is, in the example of FIG. 3, the tilt controller 320 uses the amount of light measured at the detection position as the tilt error signal by using the following equation.

Figure 112008049541599-PAT00001

Figure 112008049541599-PAT00002

At this time, T t represents the tilt error in the tangential direction, and R t represents the tilt error in the radial direction. In addition, a, b, c, and d represent the light amount in A, B, C, and D of FIG. 3, respectively.

As described above, in the embodiment of the present invention, without detecting the light amount of the entire data area, several detection positions are set and only a portion of the light amount is detected to detect the tilt. Thus, the effect of tilt detection on the data rate can be minimized.

The tilt compensator 330 compensates for the tilt using the tilt detected by the tilt controller 320 as described above. Radial and tangential biaxial deck mechanisms can be used to compensate for this tilt. The tilt of the recording medium 100 can be corrected in real time using the tilt error signal and the two-axis deck mechanism calculated in the above manner. At this time, since the detection of the radial tilt is easy when there is a tangential tilt, it is preferable to perform the correction of the radial tilt first.

The configuration of the recording and reproducing apparatus described above is for illustrating the present invention and the present invention is not limited thereto. In addition, each component may be in the form of software or hardware, respectively, or may be in the form of a combination of software and hardware, respectively. In addition, if necessary, each component may be separately configured in a separate configuration, or a plurality of components may be integrated into one.

4A and 4B show the relationship between the tilt error signal and the quality of the reproduced data. It can be seen that the quality of the reproduced data is improved by correcting the tilt error, that is, when each tilt error signal becomes zero. have.

Hereinafter, a tilt compensation method of a recording medium according to an embodiment of the present invention will be described in detail. 5 is a flowchart illustrating a tilt compensation method of a recording medium according to an embodiment of the present invention. A tilt compensation method will be described with reference to FIG. 5.

First, a data image is acquired (S100), and the amount of light is measured in the data image (S200). In this case, in order to measure the amount of light in the data image, a plurality of detection positions spaced apart from each other may be set to be symmetric to each other in the tangential direction and the radial direction.

For example, the plurality of detection positions can be set to include four detection units as shown in FIG. 3. However, the detector may be further configured as necessary. The partial decrease in the amount of light is respectively measured at such a plurality of detection positions.

Next, the tilt of the recording medium is detected based on the amount of light measured as described above (S300). At this time, for example, the tilt in the tangential and radial directions may be detected by using an expression such as Equation 1 and Equation 2.

Next, the detected tangent and the tilt in the radial direction are compensated for (S100). At this time, as described above, it is possible to compensate for the tilt in real time using a two-axis deck mechanism.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications and changes can be made within the scope of the claims and the detailed description of the invention and the accompanying drawings, and the present invention is also provided. Naturally, it belongs to the range of.

1 is a schematic diagram showing a recording / playback apparatus according to an embodiment of the present invention.

2 is a view showing an example of a change in the amount of light in a data image due to the tilt of the recording medium.

3 is a schematic diagram illustrating a detection position in a data image.

4A and 4B are graphs showing the relationship between the tilt error signal and the quality of the reproduction data.

5 is a flowchart illustrating a tilt compensation method according to an embodiment of the present invention.

Claims (14)

Acquiring a data image reproduced from a recording medium; Measuring the amount of light in the data image; Detecting the tilt of the recording medium based on the measured amount of light; And Compensating for the detected tilt Tilt compensation method of a recording medium comprising a. According to claim 1, Measuring the amount of light, Setting a plurality of detection positions in the data image; And Measuring a partial decrease in the amount of light at each of the plurality of detection positions Tilt compensation method of a recording medium comprising a. The method of claim 2, And in the setting of the plurality of detection positions, setting the plurality of detection positions apart from each other. The method of claim 3, wherein And tilting the plurality of detection positions so as to be symmetrical with each other in a tangential direction and a radial direction of the recording medium. The method of claim 4, wherein The plurality of detection positions, A first detector configured at an arbitrary position of the data image; A second detector set at a position symmetrical with the first detector in the tangential direction; A third detector set at a position symmetrical with the first detector in the radial direction; And A fourth detector set at a position symmetrical with the third detector in the tangential direction Tilt compensation method of a recording medium comprising a. The method of claim 5, Detecting the tilt, Detecting the tilt in the tangential direction and the tilt in the radial direction based on the amount of light measured by the first to fourth detectors. The method of claim 6, Compensating the tilt, Compensating for the detected radial tilt and the tangential tilt Tilt compensation method of a recording medium comprising a. An image detector for acquiring a reproduced data image from a recording medium and measuring an amount of light of the data image; A tilt controller which detects the tilt of the recording medium based on the amount of light measured by the image detector and controls tilt compensation; And Tilt compensation unit for compensating the tilt of the recording medium under the control of the tilt control unit Tilt compensation device of a recording medium comprising a. The method of claim 8, And the image detector is configured to measure a reduction in a partial amount of light at each of a plurality of detection positions set in the data image. The method of claim 9, And the plurality of detection positions are set apart from each other. The method of claim 10, And the plurality of detection positions are set to be symmetrical with each other in a tangential direction and a radial direction of the recording medium. The method of claim 11, wherein The plurality of detection positions, A first detector configured to set any of the data images at a position; A second detector set at a position symmetrical with the first detector in the tangential direction; A third detector set at a position symmetrical with the first detector in the radial direction; And A fourth detector set at a position symmetrical with the third detector in the tangential direction Tilt compensation device of a recording medium comprising a. The method of claim 12, The tilt control unit, And tilt detection in the tangential direction and tilt in the radial direction based on the amount of light measured by the first to fourth detectors. The method of claim 13, And the tilt compensator is configured to compensate the tilt in the radial direction and the tilt in the tangential direction.
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