JP2010152940A - Optical information recording and reproducing device, and optical information recording and reproducing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve reliability of recording and reproducing of management information by solving such a problem that when user data such as video is recorded in an optical disk and recording quality of management information managing the user data is reduced, reproduction of the user data cannot be performed. <P>SOLUTION: Reliability of management information is improved by reducing bit errors by improving S/N by making the number of minimum codes which a unit code of management information adjoins larger than the number of minimum codes which a unit code of the user data adjoins. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical information recording / reproducing apparatus that records and reproduces information by irradiating an information medium (hereinafter referred to as an optical disk) with light.

  At present, optical discs having a recording density of about 50 GB are being commercialized for consumer use in accordance with the Blu-ray Disc (BD) standard using a blue-violet semiconductor laser.

  In the future, it is considered that the capacity of the optical disc will increase to the same extent as the HDD (Hard Disc Drive) capacity of 100 GB to 1 TB.

  However, in order to realize such an ultra-high density with an optical disk, a new storage technology that is different from the trend of the conventional high-density technology due to the shorter wavelength and the higher NA of the objective lens is required. Become.

  While research on next-generation storage technology is underway, hologram recording technology that records digital information using holography is attracting attention.

  The hologram recording technique is a method in which a signal light having page data information two-dimensionally modulated by a spatial light modulator and a reference light are superimposed inside the recording medium, and an interference fringe pattern generated at that time causes the inside of the recording medium. This is a technique for recording information by causing refractive index modulation in the optical disk.

  When reproducing the information, if the recording medium is irradiated with the reference light used for recording in the same arrangement, the hologram recorded in the recording medium acts like a diffraction grating to generate diffracted light. This diffracted light is reproduced as the same light including the recorded signal light and phase information.

  The reproduced signal light is detected two-dimensionally at high speed using a photodetector such as a CMOS or CCD. Thus, in hologram recording, two-dimensional information can be simultaneously recorded / reproduced by one hologram, and a plurality of page data can be overwritten at the same location, so that large-capacity and high-speed information can be recorded / reproduced. It is valid.

  As a hologram recording technique, for example, there is JP-A-2004-272268 (Patent Document 1). In this publication, a signal beam is condensed on an optical information recording medium by a lens, and simultaneously, a hologram is recorded by irradiating and collimating a reference beam of a parallel beam, and further determining the incident angle of the reference beam on the optical recording medium. A so-called angle multiplex recording method is described in which multiplex recording is performed by displaying different page data on a spatial light modulator while changing. Furthermore, in this publication, the distance between adjacent holograms can be shortened by condensing the signal light with a lens and providing an aperture (spatial filter) in the beam waist, which is compared with the conventional angle multiplex recording system. A technique for increasing the recording density / capacity is described.

  Further, as a hologram recording technique, for example, there is WO2004-102542 (Patent Document 2). In this publication, in one spatial light modulator, light from an inner pixel is signal light, light from an outer ring-shaped pixel is reference light, and both light beams are condensed on an optical recording medium with the same lens. An example is described in which a shift multiplexing method is used in which a hologram is recorded by causing signal light and reference light to interfere with each other in the vicinity of the focal plane of the lens.

JP 2004-272268 A WO2004-102542

  When recording user data such as video on the optical disc, management information for managing the user data is also recorded on the optical disc. This management information is required to have higher reliability than user data. If the management information cannot be reproduced, even if the recording quality of the user data is good, the optical disc cannot be reproduced and the recorded video cannot be viewed.

  Possible causes of deterioration in recording quality include deterioration of recording power adjustment accuracy, laser wavelength change due to temperature changes in the vicinity of the laser, and defects such as fingerprints and scratches. It becomes impossible to reproduce beyond the limit of correction. In particular, in a rewritable disc, management information is frequently updated, and overwriting is performed many times, so that it is likely to be impossible to reproduce due to deterioration of jitter and exhaustion of the recording film.

  Also, with the recent increase in capacity of optical discs, the unit code length of unit codes representing code 0 and code 1 has become shorter, and if recording is performed with improper adjustment of laser power, laser beam irradiation angle, and focus, reproduction is possible. Sometimes a lot of bit errors occur, which makes it difficult to reproduce. On the other hand, if the unit code lengths of user data and management information are increased at the same time, the maximum recording capacity of the optical disk decreases, which is not appropriate.

  Thus, conventionally, management information is required to have higher reliability than user data, whereas both user data and management information have the same unit code length, so the reliability of recording and reproduction is the same. As a result, the recording quality relative to the reliability requirement level was relatively unsecured by the management information.

  Therefore, an object of the present invention is to improve the reliability in recording and reproducing management information while maintaining the recording capacity of user data.

  The above object is achieved by the invention described in the claims as an example.

  According to the present invention, since the minimum number of codes of management information is greater than the minimum number of codes of user data, S / N (Signal to Noise) is improved. Therefore, by improving the recording / reproduction quality of the management information, it is possible to solve the problem that the video cannot be reproduced due to a bit error of the management information exceeding the reference, and the convenience for the user is increased.

  In the optical information recording / reproducing apparatus according to the present invention, in order to improve the reliability of recording / reproducing management information, the number of adjacent unit codes in the user data and the management information is minimized (hereinafter referred to as the minimum code number). It is possible to record the information by encoding differently and making the minimum number of codes of management information larger than the minimum number of codes of user data. In general, since management information has a smaller amount of information than user data, even if the minimum code length of management information is made larger than the minimum code length of user data, the influence of the increase in management information on the capacity of the entire optical disc is small.

  As an example, in the case of a hologram recording / reproducing apparatus, unit codes are two-dimensionally arranged and recorded / reproduced at one time by one hologram, but user data assigns 1 bit to one unit code (hereinafter, pixel). On the other hand, in the management information, 1 bit is assigned to two or more adjacent pixels.

  As another example, in the case of an optical disc apparatus in which recording tracks are formed in a spiral shape, unit codes are arranged one-dimensionally and recorded and reproduced for each unit code. 1 bit is assigned to a 1T code with a clock period of 1T, whereas management information assigns 1 bit to a code having a code length adjacent to two or more 1T codes.

  Hereinafter, examples of the present invention will be described in more detail.

  FIG. 1 is an overall configuration diagram of an optical information recording / reproducing apparatus for recording / reproducing digital information using holography.

  The optical information recording / reproducing apparatus 100 includes a phase conjugate optical system 102, a motor 103, and a pickup 104, and is configured to rotate the optical disc 101 and irradiate the optical disc with light.

  The pickup 104 plays a role of emitting reference light and signal light to the optical disc 101 and recording digital information using holography.

  At this time, the information signal to be recorded is sent by the controller 108 to the spatial light modulator (to be described later) in the pickup 104 via the signal processing means 105, and the signal light is modulated by the spatial light modulator.

  Data is spatially arranged in a two-dimensional form by the spatial light modulator, and a large amount of information can be recorded by irradiating the optical disk 101 with a single light, enabling large-capacity recording and high-speed recording.

  When reproducing information recorded on the optical disc 101, the phase conjugate light of the reference light emitted from the pickup 104 is generated by the phase conjugate optical system 102. Here, the phase conjugate light is a light wave that travels in the opposite direction while maintaining the same wavefront as the input light. Reproduction light reproduced by the phase conjugate light is detected by a photodetector described later in the pickup 104, and a signal is reproduced by the signal processing means 105.

  Information signals to be recorded / reproduced are transmitted to an external device through the interface 109.

  FIG. 2 shows an example of the optical system configuration of the pickup 104 in the optical information recording / reproducing apparatus 100.

  The light beam emitted from the light source 201 is incident on a polarization beam splitter (PBS) prism 202. The light beam transmitted through the PBS prism 202 enters the spatial light modulator 204 via the PBS prism 203.

  The signal light 206 to which information is added by the spatial light modulator 204 passes through the PBS prism 203 and is condensed on the optical disc 101 by the objective lens 207.

  On the other hand, the light beam reflected from the PBS prism 202 enters the mirror 208. Since the angle of the mirror 208 can be adjusted, the incident angle of the reference light 209 that enters the optical disc 101 after passing through the lens 210 can be set to a desired angle.

  In this manner, the signal light 206 and the reference light 209 are incident on the optical disc 101 so as to overlap each other, whereby an interference fringe pattern is formed in the optical disc 101, and information is recorded by writing this pattern on the recording medium. . Further, since the incident angle of the reference light 209 incident on the optical disk 101 can be changed by the mirror 208, recording by angle multiplexing is possible.

  When reproducing the recorded information, the reference light 209 is incident on the optical disc 101 and the light beam transmitted through the optical disc 101 is reflected by the mirror 211 as described above, thereby generating the phase conjugate light.

  The reproduced light beam reproduced by the phase conjugate light is transmitted through the objective lens 207, reflected by the PBS prism 203 and incident on the photodetector 205, and the recorded signal can be reproduced.

  Hereinafter, information encoding / decoding means will be described.

  In FIG. 1, a signal processing unit 105 includes a first code decoding unit 106 for encoding / decoding user data and a second code decoding unit 107 for encoding / decoding management information. Here, for example, the amount of user data is 300 GB per optical disc, and the management information is 10 MB such as the date and title of video information. The amount of information and the content of information may be other than these.

  FIG. 3 is a schematic diagram showing a flow of the first code decoding means 106 for encoding / decoding user data.

  192512 bytes are extracted from the data 301 to generate rearrangement data 302 of 1024 bytes × 188 rows. Next, a page number, a header, and a footer are added, and an error correction code is added to generate (1072 bytes + 560 bytes) × (188 lines + 20 lines) error correction code additional data 303. Thereafter, 8 / 16-bit conversion 304 is performed to convert 8-bit data into 16-bit image information of 4 × 4 = 16 dots, and a data page image in which digital information is arranged in a two-dimensional form is generated, and data on the optical disk 101 Record.

  FIG. 4 is a schematic diagram of two-dimensional array information. The data page 401 includes a page synchronization mark 402 and 51 subpages 403, and has 1632 bytes of data. The subpage 403 includes a subpage synchronization mark 404 and 32 symbols 405, and has 32 bytes of data. The symbol 405 includes 4 rows × 4 columns = 16 unit codes (pixels), and uses 3 unit codes 1 (hereinafter referred to as on-pixel 406) and 13 unit codes 0 (hereinafter referred to as off-pixel 407). It has 1 byte data.

  FIG. 5 is a schematic diagram of 8/16 bit conversion. A bit number is assigned to the 8-bit data 501 from the most significant bit 7 to the least significant bit 0, and is set to 00000101 as an example. The 8-bit data 501 is converted into 16-bit data 502 assigned to the bit numbers from the most significant bit 15 to the least significant bit 0. The bit number of the 16-bit data 502 corresponds to the pixel number of the symbol data 503, the code 1 of the 16-bit data 502 corresponds to the on pixel of the symbol data 503, and the code 0 corresponds to the off pixel.

  At this time, the on-pixel is not adjacent vertically and horizontally, and the minimum code number of the on-pixel is 1. Note that the decryption of the user data may be performed in the reverse order of the above procedure.

  FIG. 6 is a schematic diagram of 8/64 bit conversion for encoding / decoding management information. The management information encoding / decoding is realized by replacing the 8 / 16-bit conversion in FIG. 3 with the 8 / 64-bit conversion. A bit number is assigned to the 8-bit data 501 from the most significant bit 7 to the least significant bit 0, and is set to 00000101 as an example. The 8-bit data 501 is converted into 64-bit data 601 assigned to the bit numbers from the most significant bit 63 to the least significant bit 0. The bit number of the 64-bit data 601 corresponds to the pixel number of the symbol data 602. The code 1 of the 64-bit data 601 corresponds to the on pixel of the symbol data 602, and the code 0 corresponds to the off pixel.

  At that time, 2 pixels × 2 columns = 4 on-pixels are adjacent to each other, and the minimum code number of the on-pixel is 4. The on-pixel arrangement may be 1 row × 2 columns or 1 row × 4 columns, and the minimum code number may be other than 4. The management information may be decrypted by reversing the above procedure.

  Thus, while the user data has a minimum code number of 1 and the management information has a minimum code number of 4, the data recording amount of the management information becomes 1/4, but it is effectively on-pixel. The area can be increased. As a result, the S / N is improved, and the bit error can be reduced even when the resolution of the photodetector of the reproduction signal is low, so that the quality of recording / reproduction is improved.

  When the minimum number of codes is different between user data and management information, if the number of on-pixel appearances in a certain area is different, the power to be applied to the optical disc is set as the user data recording area and the management information recording area. It becomes necessary to decide individually. Therefore, it is desirable that the number of on-pixel appearances within a certain region be the same.

  FIG. 7 is a schematic diagram showing a part of subpages in 8 / 16-bit conversion and 8 / 64-bit conversion. When attention is paid to symbol numbers 21, 22, 27, and 28 as an example in the subpage 403, these are composed of 8 rows × 8 columns = 64 pixels. A part 701 of the subpage in the 8 / 16-bit conversion includes 4 symbols of 3 on pixels, and there are 12 on pixels. This has 4 bytes of information.

  On the other hand, a part 702 of the subpage in the 8/64 bit conversion includes three on pixels having a minimum code number of 4, and there are 12 on pixels. This has 1 byte of information.

  In this way, the number of on pixels existing in the data page 401 in the 8 / 16-bit conversion and the 8 / 64-bit conversion is the same.

  As a result, there is no difference between the 8 / 16-bit conversion and the 8 / 64-bit conversion in the amount of light applied to the disk through the spatial light modulator 204, and the laser light power can be made the same. Accordingly, it is possible to reduce the number of adjustments and adjustment time of the power for irradiating the optical disc 101 with light.

  When recording user data and management information, it is necessary to switch between the first code decoding means 106 and the second code decoding means 107. The switching method will be described.

  FIG. 8 is a schematic diagram of the discrimination information pattern. In the header data in the error correction additional data 303, the first discrimination information pattern 801 is embedded in the case of user data, and the second discrimination information pattern 802 is embedded in the case of management information. Here, the first discrimination information pattern 801 is all 0 and the second discrimination information pattern 802 is all 1. However, other patterns such as repetition of 0 and 1 may be used.

  In accordance with this discrimination information pattern, the controller 108 switches the first code decoding means 106 or the second code decoding means 1007 to perform desired encoding. Similarly in decoding, decoding is performed according to a predetermined discrimination information pattern.

  Thus, by assigning the discrimination information pattern, the switching of the information encoding means can be clearly set. In addition, it is possible to control switching of information encoding means from a host outside the drive, and it is possible to control switching freely according to the importance of information of the host as well as the division between user data and management information, and the recording quality of any information can be controlled. Securement is possible.

  When the management information is recorded only in a predetermined area, the first code decoding means 106 and the second code decoding means 1007 may be switched according to a predetermined address on the optical disc 101. By switching according to the recording address, the header discrimination information pattern becomes unnecessary, the number of bytes in the header can be reduced, and the recording capacity can be increased.

  As described above, a 40 MB recording area is required for 10 MB management information, but the S / N in the management information is improved and recording / reproduction quality can be ensured. Therefore, it is possible to improve the reliability in recording / reproducing of the optical disk while maintaining the user data recording amount of 300 GB.

  An optical information recording / reproducing apparatus taking as an example a Blu-ray Disc having a capacity of 50 GB of user data per optical disk will be described. Here, the management information has 10 MB of information such as video date and title. The capacity of the user data and management information may be other than this, and the management information may be other than the date and title of the video. The optical disc 101 using this optical Blu-ray Disc as an example has a spiral track, and code data is arranged and recorded in a one-dimensional manner with respect to one track.

  The basic configuration is the same as that of the first embodiment, and includes an optical disc 101, a pickup 104, a signal processing unit 105, a first code decoding unit 106, a second code decoding unit 107, and a controller 108. User data or management information is encoded / decoded by switching between the first code decoding means 106 and the second code decoding means 107 in accordance with a predetermined discrimination information pattern or recording address.

  FIG. 9 shows a schematic diagram of the one-dimensional array information. The encoded first code information 901 includes data in which 2 to 9 codes 0 or 1 are consecutive. If the clock period is 1T, 2T to 9T are obtained. Here, the minimum code number is 2.

  On the other hand, the second code information 902 is composed of data in which the code length is doubled and the code 0 or the code 1 is consecutively 4 to 18 pieces, and is 4T to 18T. Here, the minimum number of codes is 4.

  Thus, by setting the minimum number of codes to 2 for user data and the minimum number of codes to 4 for management information, it is possible to suppress the deterioration of the recording quality of the densest pattern and improve the reliability of recording and reproducing management information. It becomes.

  Here, the code length of the management information is set to be twice the code length of the user data, but other lengths such as one obtained by adding 1 to the code length may be used.

  As described above, a 40 MB recording area is required for 10 MB management information, but the S / N in the management information is improved and recording / reproduction quality can be ensured. Therefore, it is possible to improve the reliability in recording / reproducing of the optical disk while maintaining the user data recording amount of 50 GB.

1 is an overall configuration diagram of an optical information recording / reproducing apparatus in a first embodiment. FIG. 3 is a configuration diagram of a pickup in the first embodiment. Schematic which shows the flow of the 1st code | symbol decoding means in a 1st Example. The schematic of the two-dimensional arrangement | sequence information in a 1st Example. Schematic of 8/16 bit conversion in the first embodiment. Schematic of 8/64 bit conversion in the first embodiment. The partial schematic diagram of the subpage in a 1st Example. Schematic of the discrimination information pattern in the first embodiment. The schematic diagram of the one-dimensional arrangement | sequence information in a 2nd Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Optical information recording / reproducing apparatus 101 ... Optical disk 102 ... Phase conjugate optical system 103 ... Motor 104 ... Pickup 105 ... Signal processing means 106 ... 1st code decoding means 107 ... second code decoding means 108 ... controller 109 ... interface 201 ... light source 202 ... PBS prism 203 ... PBS prism 204 ... spatial light modulator 205 ... light detection 206 ... Signal light 207 ... Lens 208 ... Mirror 209 ... Reference light 210 ... Lens 211 ... Mirror 301 ... Data 302 ... Sort data 303 ... Error Correction code added data 304... 8/16 bit conversion 305... Data page image 401... Data page 402. Mark 403 ... Subpage 404 ... Subpage synchronization mark 405 ... Symbol 406 ... On pixel 407 ... Off pixel 501 ... 8 bit data 502 ... 16 bit data 503 ... Symbol data 601 ... 64-bit data 602 ... Symbol data 701 ... Part of subpage 702 in 8 / 16-bit conversion ... Part of subpage 801 in 8 / 64-bit conversion ... 1 discriminating information pattern 802... 2nd discriminating information pattern 901... First code information 902.

Claims (14)

An optical information recording / reproducing apparatus capable of recording and reproducing binary unit codes of code 0 and code 1 as digital information by irradiating light onto an information medium,
Optical means for irradiating the information medium with light;
The number that minimizes the number of adjacent codes 1 is the minimum code number,
Encoding first information into first code information having a first minimum code number, and first code decoding means for decoding the first code information into the first information;
The second information is encoded into second code information having a second minimum code number larger than the first minimum code number, and the second code information is decoded into the second information. An optical information recording / reproducing apparatus comprising: a second code decoding means. The optical information recording / reproducing apparatus according to claim 1,
Means for adding first discrimination information to the first information;
An optical information recording / reproducing apparatus comprising means for adding second discrimination information to the second information. The optical information recording / reproducing apparatus according to claim 2,
According to the first discrimination information or the second discrimination information,
An optical information recording / reproducing apparatus comprising control means for switching between the first code decoding means and the second code decoding means. The optical information recording / reproducing apparatus according to claim 1,
Depending on the recording area of the information medium,
An optical information recording / reproducing apparatus comprising control means for switching between the first code decoding means and the second code decoding means. The optical information recording / reproducing apparatus according to claim 1,
An optical information recording / reproducing apparatus comprising means for two-dimensionally arranging the code 0 and the code 1 and recording the information on the information medium. The optical information recording / reproducing apparatus according to claim 5,
A total number of the codes 1 arranged in the two-dimensional form in the first code information;
An optical information recording / reproducing apparatus comprising: means for making the total number of the codes 1 arranged two-dimensionally in the second code information substantially the same within the same area. The optical information recording / reproducing apparatus according to claim 1,
An optical information recording / reproducing apparatus comprising means for arranging the code 0 and the code 1 in a one-dimensional manner and recording the information on the information medium. An optical information recording / reproducing method capable of recording / reproducing binary unit codes of code 0 and code 1 as digital information by irradiating light onto an information medium,
Irradiating the information medium with light,
The number that minimizes the number of adjacent codes 1 is the minimum code number,
A first code decoding method for encoding the first information into first code information having a first minimum code number, and decoding the first code information into the first information;
The second information is encoded into second code information having a second minimum code number larger than the first minimum code number, and the second code information is decoded into the second information. An optical information recording / reproducing method characterized by the second code decoding method. The optical information recording / reproducing method according to claim 8,
Adding first discrimination information to the first information;
An optical information recording / reproducing method comprising adding second discrimination information to the second information. The optical information recording / reproducing method according to claim 9,
According to the first discrimination information or the second discrimination information,
An optical information recording / reproducing method, wherein the first code decoding method and the second code decoding method are switched. The optical information recording / reproducing method according to claim 8,
Depending on the recording area of the information medium,
An optical information recording / reproducing method, wherein the first code decoding method and the second code decoding method are switched. The optical information recording / reproducing method according to claim 8,
An optical information recording / reproducing method, wherein the code 0 and the code 1 are two-dimensionally arranged and recorded on the information medium. The optical information recording / reproducing method according to claim 12,
A total number of the codes 1 arranged in the two-dimensional form in the first code information;
An optical information recording / reproducing method characterized in that the total number of the codes 1 arranged in a two-dimensional manner in the second code information is substantially the same within the same area. The optical information recording / reproducing method according to claim 8,
An optical information recording / reproducing method, wherein the code 0 and the code 1 are arranged one-dimensionally and recorded on the information medium.

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