KR20080010130A - Method and apparatus for reproducing data - Google Patents

Abstract

A method and an apparatus for reproducing data are provided to detect data effectively which is reproduced continuously by obtaining images at the optimum point. An apparatus for reproducing data comprises a beam source(10), an actuator(20), an image sensor(18), a photo detector(19), and a control unit(14). The actuator includes a reflection mirror projects a first beam emitted from the beam source to a recording medium. The image sensor receives reproduction beam diffracted from the recording medium. The photo detector detects the reproduction beam projected to the image sensor. The control unit controls image obtaining of the image sensor according to signal output of the photo detector.

Description

Data reproducing apparatus and method {Method and apparatus for reproducing data}

1 is a configuration diagram schematically showing a data recording and reproducing apparatus according to an embodiment of the present invention.

2 is a diagram illustrating a data reproduction method according to the present invention.

3 and 4 illustrate an error signal detected by a photo detector during a process in which a reference beam is incident on one page while the recording medium is rotated when a plurality of pages are continuously reproduced.

Disclosed is a data reproducing apparatus and method.

Representative examples of recording media on which data is recorded include CD (Compact Disc) and DVD (Digital Versatile Disc). CD and DVD are recording media for storing data using spots of beams emitted from a laser light source.

CD or DVD uses a method of increasing the storage capacity by adjusting the pitch interval or increasing the recording layer, but due to physical limitations, it is no longer possible to increase the storage capacity.

Meanwhile, with the development of multimedia technology, there is a demand for a recording medium capable of storing more data, a data recording device capable of storing data on such a recording medium, and a data reproducing apparatus capable of reproducing the recording medium.

Accordingly, in recent years, studies on holographic data recording and reproducing apparatus using light interference and diffraction have been actively conducted.

The holographic data recording and reproducing apparatus uses an interference fringe generated by interference of a signal beam and a reference beam.

That is, when a signal beam and a reference beam are irradiated to a recording medium, an interference fringe is formed by the interference between the signal beam and the reference beam, and the interference fringe is thus recorded on the storage medium. When the reference beam is irradiated to the storage medium storing the interference fringe, the recorded data is reproduced while diffracting the reference beam from the interference fringe stored in the storage medium.

At this time, the hologram data recorded on the recording medium can be read only by the reference beam used in the recording process, and cannot be read by the reference beam having a different wavelength or phase from the reference beam used at the time of recording, Pass the hologram data.

By using this hologram property, a large amount of hologram data is recorded in the same place on the recording medium with different reference beams, thereby making it possible to store a large amount of data inside a small recording medium.

The commonly used angular multiplexing technique is to change the angle of the reference beam for each recording to create different reference beams, which allows hundreds to thousands of holographic data to be stored per page. Can be stored in the same place In other words, by recording a lot of data in units of pages in the same place, it is possible to record with high storage density.

Here, since the incident angle and the incident position at which the reference beam is incident on the recording medium should be changed, an actuator for adjusting the incident angle and the incident position of the reference beam is required.

On the other hand, when reproducing the holographic data recorded by the angular overlap technique, the incident angle of the reference beam incident on the recording medium should be changed in the same manner as in recording.

However, it is not efficient to reproduce the data by changing the incident angle of the reference beam for each page where the holographic data is stored.

In addition, since the image must be obtained accurately when the reference beam is incident on the holographic data, a technique for precisely controlling the operation time of the image sensor is required.

It is an object of the present invention to provide a data reproducing apparatus and method capable of quickly and accurately reproducing data.

Disclosed is a data reproducing apparatus and method.

In accordance with another aspect of the present invention, a data reproducing apparatus includes a light source, an actuator in which a reflection mirror is formed so that a first beam emitted from the light source is incident on a recording medium, and an image sensor which receives reproduction light diffracted from the recording medium and converts the signal into an electrical signal. And a photo detector for sensing the reproduction light incident to the image sensor, and a controller for controlling image acquisition of the image sensor according to the signal of the photo detector.

In addition, the data reproducing method according to the present invention includes the steps of loading a recording medium, reproducing data recorded in a plurality of pages by causing a first beam to be incident on the recording medium at a first incident angle, and And reproducing the data recorded in the plurality of pages by allowing the first beam to be incident at the second incident angle.

The data reproducing apparatus and method according to the present invention can reproduce data quickly and accurately.

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

1 is a configuration diagram schematically showing a data recording and reproducing apparatus according to an embodiment of the present invention.

Referring to FIG. 1, a data recording and reproducing apparatus according to the present invention includes a shutter 11 for blocking or passing a beam generated from a light source 10, and a signal beam for receiving a beam incident from the shutter 11. A beam splitter 12 that separates the path S1 of the < RTI ID = 0.0 > (S) < / RTI > and the path S2 of the reference beam, and a recording medium 16 on which data is recorded due to interference between the signal beam and the reference beam. .

In detail, the light source 10 may be a laser diode emitting a beam having a wavelength of 405nm or 532nm, the beam splitter 12 transmits the beam by reflecting the incident beam according to the polarization direction A polarization beam splitter (PBS) for separating may be used.

In addition, the shutter 11 operates on / off to allow the beam emitted from the light source 10 to be intermittently passed. At this time, the progress of the beam may be controlled by controlling the light source 10 on / off without providing the shutter 11. The data recording and reproducing apparatus according to the embodiment of the present invention may allow the shutter 11 to store or reproduce data in units of pages during recording and reproduction.

In addition, the signal path processing path S1 includes an actuator 20 in which a reflection mirror 17 for changing a traveling angle of the reference beam is formed.

In detail, the reflective mirror 17 reflects the reference beam separated by the beam splitter 12 to be incident on the recording medium 16, and the actuator 20 drives the reflective mirror 17. The incident position or the incident angle of the reference beam incident on the recording medium 16 is changed.

Accordingly, the signal beam processing path S1 serves to provide the recording medium 16 with a recording or reproducing reference beam required for recording or reproducing hologram data.

In addition, the signal beam processing path S1 includes a spatial light modulator (SLM) 13 that carries input data to be recorded in the signal beam separated from the beam splitter 12.

In detail, the spatial light modulator 13 may be formed of a liquid crystal on silicon (LCoS) panel, and loads input data, that is, data stored in units of pages, in a signal beam passing through the beam separator 12. give.

The signal beam into which the data is input is incident on the recording medium 16 through the objective lens 15.

In addition, the recording medium 16 is located on an optical path where a signal beam output from the spatial light modulator 13 and a reference beam reflected from the reflecting mirror 17 cross each other, and the signal beam and the reference beam The interference fringe generated by the interference of is recorded, and the interference fringe recorded by the irradiation of the reference beam is restored and output.

In addition, the data recording and reproducing apparatus according to the present invention includes an image sensor 21 for reproducing data recorded on the recording medium 16, and a photo detector 19 for detecting the amount of light incident on the image sensor 21. And a control unit 14 for controlling the operation of the image sensor 21 according to the signal detected by the photo detector 19.

Specifically, the image sensor 21 is located on the optical path of the diffracted light generated when the reference beam is incident on the recording medium 16, and when restoring the interference fringe recorded on the recording medium 16, Convert it to the original electrical signal. In general, a complementary metal-oxide semiconductor (CMOS) sensor may be used as the image sensor 21.

In addition, the photo detector 19 detects the amount of light incident on the image sensor 21 to allow the controller 14 to control the image acquisition time of the image sensor 21.

Next, the operation of the data recording and reproducing apparatus according to the present invention configured as described above will be described.

First, the laser beam generated by the light source 10 passes through the shutter 11 and is separated into a reference beam and a signal beam by the beam splitter 12.

In addition, the signal beam separated by the beam splitter 12 is incident to the spatial light modulator 13 and then enters the storage medium 16 after data to be recorded is included in units of pages.

In addition, the reference beam separated by the beam splitter 12 is changed at a predetermined angle by the reflecting mirror 17 driven by the actuator 20 and is incident on the recording medium 16.

Then, the signal beam and the reference beam cause interference in the recording medium 16, and the interference fringes generated at this time are recorded on the recording medium 16.

After one page is recorded as described above, the next page is applied with a reference beam having a slightly different angle of the reflection mirror 17. That is, after writing the first page of data to the storage medium 16, when the laser beam generated from the light source 10 is temporarily blocked by the shutter 11 and then passed again, the angle of the reference beam is changed to a different angle. As a reference beam, a new data page is input and written to the storage medium 16.

In this case, the reference beams are formed to be slightly different from each other by the driving of the actuator 20 so that the reference beams correspond to the respective pages, so that the reference beams enter the storage medium 16 at different angles. Can be.

Therefore, by repeating the process of changing the angle of the reference beam for each page recording, hologram data can be superimposed on the recording medium 16 to record a large amount of data at the same place in units of pages. Data recording becomes possible.

In addition, in order to reproduce the data recorded on the recording medium 16, only the reference beam is incident on the recording medium 16.

Here, the reference beam incident on the recording medium 16 at the time of reproduction should be incident at the same angle as the reference beam incident on the recording, which can be adjusted by the driving of the actuator 20.

Therefore, when a reference beam having an angle equal to the recording angle of the reference beam at the time of recording is irradiated to the recording medium 16, the interference fringe recorded on the recording medium 16 diffracts the reference beam to contrast the original pixels. It is restored to a checkerboard consisting of.

And, if the read image is illuminated on the image sensor 21, the original recorded data can be reproduced.

Meanwhile, in the present invention, when the data stored in the recording medium 16 is reproduced, the pages included in one book stored as a plurality of pages are not continuously reproduced by the angular overlapping technique, but are reproduced by the reference beam of the same incident angle. Data is continuously reproduced by continuously reproducing pages included in a plurality of possible books, and then changing the incident angle of the reference beam.

2 is a diagram illustrating a data reproduction method according to the present invention.

Referring to FIG. 2, data in units of a plurality of books 30 and 35 composed of a plurality of pages 31 to 34 and 36 to 39 are recorded on the recording medium 16.

Conventionally, since the book-based reproduction method is used, the first page 31 is reproduced by allowing the reference beam to enter the first page 31 included in the first book 30, and then the second page 32 A method of changing the angle of incidence so that the reference beam is incident on the?

However, in the present invention, the first book 31 included in the first book 30 can be reproduced in order to increase data reproduction efficiency, and the second book 35 included in the second book 35 can be reproduced with a reference beam of the same incident angle. Play page 31.

Then, the second page 32 included in the second book 35 capable of reproducing the second page 32 included in the first book 30 by changing the incidence angle of the reference beam and reproducing the reference beam of the same incident angle ( 32).

According to this method, data can be reproduced more quickly because the incident angle of the reference beam does not have to be changed for each page on which data is recorded.

That is, since the recording medium 16 can be rotated in the first direction S3, pages that can be reproduced with reference beams having the same incident angle are continuously reproduced and output as the recording medium 16 is rotated.

3 and 4 illustrate an error signal detected by a photo detector during a process in which a reference beam is incident on one page while the recording medium is rotated when a plurality of pages are continuously reproduced.

3 and 4, when a reference beam having the same incident angle is incident on the recording medium 16 while the recording medium 16 is rotated, light diffracted by a plurality of pages that can be reproduced with the same reference beam is detected by a photo detector ( 19) and the image sensor 18.

3 illustrates a two-split photo detector 19. When a page of the recording medium 16 passes at a position where a reference beam is incident as the recording medium 16 rotates, the photo detector 19 may be incident to the photo detector 19. It is incident as it passes by.

As can be seen from (a) to (e) of Fig. 3, the incident light of the photo detector 19 is incident as if moving in the vertical direction, and when the incident light is at the position shown in (c), the image sensor ( In 18) the correct image can be obtained.

On the other hand, Figure 4 shows an error signal (Error Signal) 41 indicating the light quantity difference between the cell (A) located above the photo detector 19 and the cell (B) located below, the cell (located above) An enable signal 40 is shown that represents the sum of the amounts of light from A) and the cell B located below.

As described above, when the incident light of the photo detector 19 is at the position of (c), that is, when the error signal 41 is '0', the image sensor 18 can obtain an optimal image. .

However, even when the reference beam is located between the pages and the page, the error signal 41 becomes '0', so that there is no distinction between the case where there is no incident light of the photo detector 19 and the case where the incident light is optimal.

Accordingly, in the present invention, the case where the incident light of the photo detector 19 is optimal using the enable signal 40 representing the sum of the amounts of light of the cell A located above and the cell B located below is optimal. To identify.

If there is no incident light of the photo detector 19, since the enable signal 40 is '0', the incident light of the photo detector 19 may be distinguished from the optimal case.

In the present invention, when the error signal 41 of the photo detector 19 is '0' and the enable signal 40 is the maximum, it is determined that the image is incident to the image sensor 18 in an optimal state.

Accordingly, the controller 14 acquires an incident image by operating the image sensor 18 when the error signal 41 of the photo detector 19 is '0' and the enable signal 40 is maximum. do.

On the other hand, the image sensor 18 may acquire the incident image even if the optimal state is not optimal, so that the controller 14 may determine that the error signal 41 is less than or equal to the first threshold and the enable signal 40 is greater than or equal to the second threshold. The image incident on the image sensor 18 is acquired.

For example, the first threshold value may be 3, and the second threshold value may be 10. The first and second threshold values may include various sizes such as the size and performance of the photo detector 19 and the state of a page on which data is recorded. It can be changed according to factors, so it can be decided by considering this.

As described above, according to the present invention, data to be continuously reproduced can be effectively detected by acquiring an image to be reproduced at an optimum time point.

The data reproducing apparatus and method according to the present invention can reproduce data quickly and accurately.

Claims (10)

Light source, An actuator in which a reflection mirror is formed so that the first beam emitted from the light source is incident on the recording medium; An image sensor which receives the reproduced light diffracted from the recording medium and converts it into an electrical signal; A photo detector for detecting reproduction light incident to the image sensor; And a controller for controlling image acquisition of the image sensor according to the signal of the photo detector. The method of claim 1, And the controller controls the image sensor according to a difference signal and a sum signal of an optical signal detected by a plurality of cells of the photo detector. The method of claim 1, The control unit controls the image sensor according to an enable signal that is a sum signal of an error signal that is a difference signal between the optical signals incident to two regions of the photo detector and an optical signal incident to the photo detector. Device. The method of claim 3, wherein And the controller controls the image sensor to acquire an image when the error signal is less than or equal to the first threshold and the enable signal is greater than or equal to the second threshold. Loading the recording medium; Reproducing data recorded in a plurality of pages by causing a first beam to enter the recording medium at a first incident angle; And reproducing the data recorded in the plurality of pages by causing the first beam to enter the recording medium at a second incident angle. The method of claim 5, The loading of the recording medium comprises rotating the recording medium. The method of claim 5, Reproducing the data recorded in the page The first beam is incident on the page, The light diffracted in the page is incident on the photo detector, And acquiring an image by controlling the image sensor according to the signal of the photo detector. The method of claim 7, wherein The acquiring of the image may include operating the image sensor according to a difference signal and a sum signal of an optical signal detected by a plurality of cells of the photo detector. The method of claim 7, wherein The acquiring of the image may include operating the image sensor according to an enable signal, which is a sum signal of an error signal of an optical signal incident to two regions of the photo detector and an optical signal incident on the photo detector. Data playback method. The method of claim 9, And operating the image sensor when the error signal is less than or equal to the first threshold and the enable signal is greater than or equal to the second threshold.

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