WO2014083670A1 - Optical information playback device and optical information playback method - Google Patents

Abstract

There has been the problem that, in a hologram memory, there may exist luminance non-uniformity within a page as a result of diffraction intensity non-uniformity within a diffraction image, caused by a defect in a recording medium or optics. In the present invention, when reproducing two-dimensional page data from an optical information recording medium, the reproduced two-dimensional page data is partitioned, for each unit having a misalignment detection-use marker embedded in the page data, into a plurality of areas, and in the group of partitioned two-dimensional areas, AGC processing is individually performed using the luminance information of the markers.

Description

Optical information reproducing apparatus and optical information reproducing method

The present invention relates to an apparatus and method for reproducing information from a recording medium using holography.

Currently, the Blu-ray Disc (TM) standard using a blue-violet semiconductor laser has made it possible to commercialize an optical disc having a recording capacity of about 50 GB even for consumer use. In the future, it is desired to increase the capacity of optical disks to the same level as the HDD (Hard Disk Drive) capacity of 100 GB to 1 TB.

However, in order to realize such an ultra-high density with an optical disk, a high-density technology by a new method different from the high-density technology by shortening the wavelength and increasing the objective lens NA is necessary.

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

Hologram recording technology is a method in which signal light having page data information two-dimensionally modulated by a spatial light modulator is superimposed on reference light inside the recording medium, and the interference fringe pattern generated at that time is placed in the recording medium. This is a technique for recording information on a recording medium by causing refractive index modulation.

When reproducing the information, when the recording medium is irradiated with the reference light used for recording, 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.

Regenerated signal light is detected two-dimensionally at high speed using a photodetector such as a CMOS or CCD. As described above, the hologram recording technique enables two-dimensional information to be recorded on the optical recording medium at once by one hologram and further reproduces this information. Since the page data can be overwritten, large-capacity and high-speed information recording / reproduction can be achieved.

As a hologram recording technique, for example, there is JP-A-2004-272268 (Patent Document 1). This publication discloses a multiplexing method and apparatus in which holograms are spatially multiplexed by partial spatial overlap between adjacent stacks of holograms. Each stack is for example an angle, a wavelength, a phase. The full advantage of another multiplexing technique such as sign, peritropy, or fractal multiplexing can be further taken in. An amount equal to the beam waist of the signal light writing the hologram separates the individual stacks of holograms. A hologram and a hologram adjacent to the hologram are all read out simultaneously, and the adjacent hologram read out is not transmitted to the camera surface by arranging a filter at the beam waist of the reproduced data, or These undesired reproductions can be found in optical systems with limited angular passbands. Information, it is described that may be filtered. "By the intermediate plane of the angular filter.

As an AGC (Automatic Gain Control) technique in hologram reproduction, for example, there is JP 2010-15635 A (Patent Document 2). In this publication, “a two-dimensional signal conversion device that converts a two-dimensional reproduction signal obtained from page data that is two-dimensionally modulated at least partially with a constant weight code, and includes one or more two-dimensional modulation codes Two-dimensional signal grouping means for grouping the two-dimensional reproduction signals in units of the two-dimensional reproduction signals corresponding to blocks, and level values of the two-dimensional reproduction signals are divided by the two-dimensional signal grouping means. The reproduction signal level calculation means for calculating the total value summed up for each group and the level value of the two-dimensional reproduction signal are calculated by the reproduction signal level calculation means for the group to which the two-dimensional reproduction signal belongs. And a reproduction signal level normalization means for converting the two-dimensional reproduction signal by normalization based on the total value. " It has been described.

Japanese Patent Laid-Open No. 2007-65139 (Patent Document 3) describes that “information is imaged, the object light of the imaged information is interfered with the reference light, and the information is recorded as an element hologram by interference fringes. As a hologram reproducing method for reproducing data from a hologram recording medium, a partial imaging step of imaging a partial two-dimensional image, which is a partial area in the two-dimensional image of the element hologram, and a partial two-dimensional image captured in the partial imaging step From the tracking determination step for determining the tracking state with respect to the element hologram, the all-pixel imaging step for capturing the entire two-dimensional image of the element hologram at the timing when the tracking determination step determines that tracking is good, Signal processing is performed on the two-dimensional image obtained in the all-pixel imaging step. It is described as the hologram reproducing method. "Which is characterized by comprising a signal processing step of reproducing the information.

JP 2004-272268 A JP 2010-15635 A JP 2007-65139 A

By the way, in a hologram memory, uneven brightness in a page due to uneven diffraction intensity in a diffraction image may exist due to a defect in a recording medium or an optical system. In Patent Documents 2 and 3, luminance unevenness is reduced by performing standardization based on a modulation rule of a constant weight code. However, the techniques of Patent Documents 2 and 3 cannot be directly applied to codes that do not have constant weight characteristics.

Accordingly, an object of the present invention is to provide an optical information reproducing apparatus and an optical information reproducing method capable of suppressing a reduction in reproduction quality due to occurrence of luminance unevenness without being limited by a modulation rule.

The above problem is solved by, for example, the invention described in the scope of claims.

According to the present invention, it is possible to provide an optical information reproducing apparatus and an optical information reproducing method capable of suppressing a reduction in reproduction quality due to occurrence of luminance unevenness without being limited by a modulation rule.

1 is a configuration diagram illustrating an image distortion correction circuit according to a first embodiment. Schematic diagram showing an embodiment of an optical information recording / reproducing apparatus Schematic showing an embodiment of a pickup in an optical information recording / reproducing apparatus Schematic showing an embodiment of a pickup in an optical information recording / reproducing apparatus Schematic showing an embodiment of a pickup in an optical information recording / reproducing apparatus Schematic showing an embodiment of the operation flow of the optical information recording / reproducing apparatus Schematic showing an embodiment of the operation flow of the optical information recording / reproducing apparatus Schematic showing an embodiment of the operation flow of the optical information recording / reproducing apparatus Schematic showing the Example of the signal generation circuit in an optical information recording / reproducing apparatus Schematic showing the Example of the signal processing circuit in an optical information recording / reproducing apparatus Schematic showing the Example of the operation | movement flow of a signal generation circuit and a signal processing circuit Schematic showing the Example of the operation | movement flow of a signal generation circuit and a signal processing circuit Figure showing a histogram of image data Figure showing an example of page division FIG. 6 is a configuration diagram illustrating an image distortion correction circuit according to a second embodiment. FIG. 6 is a configuration diagram illustrating an image distortion correction circuit according to a third embodiment. FIG. 6 is a configuration diagram illustrating an image distortion correction circuit according to a fourth embodiment. FIG. 6 is a configuration diagram illustrating an image distortion correction circuit according to a fifth embodiment. Operational Flowchart of Image Distortion Correction Circuit in Embodiment 1 Operational flow chart of image distortion correction circuit in embodiment 2 Operational Flowchart of Image Distortion Correction Circuit in Embodiment 4 Operational Flowchart of Image Distortion Correction Circuit in Embodiment 5 Operational Flowchart of Image Distortion Correction Circuit in Embodiment 3 An example of AGC circuit and page combination circuit

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

Embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 2 is a block diagram showing a recording / reproducing apparatus of an optical information recording medium for recording and / or reproducing digital information using holography.

The optical information recording / reproducing device 10 is connected to an external control device 91 via an input / output control circuit 90. In the case of recording, the optical information recording / reproducing apparatus 10 receives the information signal to be recorded from the external control device 91 by the input / output control circuit 90. When reproducing, the optical information recording / reproducing apparatus 10 transmits the reproduced information signal to the external control apparatus 91 by the input / output control circuit 90.

The optical information recording / reproducing apparatus 10 includes a pickup 11, a reproduction reference light optical system 12, a cure optical system 13, a disk rotation angle detection optical system 14, and a rotation motor 50. The optical information recording medium 1 is a rotation motor. 50 can be rotated.

The pickup 11 plays a role of irradiating the optical information recording medium 1 with reference light and signal light and recording digital information on the recording medium using holography. At this time, the information signal to be recorded is sent by the controller 89 to the spatial light modulator in the pickup 11 via the signal generation circuit 86, and the signal light is modulated by the spatial light modulator.

When reproducing the information recorded on the optical information recording medium 1, the reproduction reference light optical system 12 generates a light wave that causes the reference light emitted from the pickup 11 to enter the optical information recording medium in a direction opposite to that during recording. Generate. Reproduction light reproduced by the reproduction reference light is detected by a photodetector (to be described later) in the pickup 11, and a signal is reproduced by the signal processing circuit 85.

The irradiation time of the reference light and the signal light applied to the optical information recording medium 1 can be adjusted by controlling the opening / closing time of the shutter in the pickup 11 via the shutter control circuit 87 by the controller 89.

The cure optical system 13 plays a role of generating a light beam used for pre-cure and post-cure of the optical information recording medium 1. Precure is a pre-process for irradiating a predetermined light beam in advance before irradiating the desired position with reference light and signal light when recording information at a desired position in the optical information recording medium 1. Post-cure is a post-process for irradiating a predetermined light beam after recording information at a desired position in the optical information recording medium 1 so that additional recording cannot be performed at the desired position.

The disk rotation angle detection optical system 14 is used to detect the rotation angle of the optical information recording medium 1. When adjusting the optical information recording medium 1 to a predetermined rotation angle, a signal corresponding to the rotation angle is detected by the disk rotation angle detection optical system 14, and a disk rotation motor control circuit is detected by the controller 89 using the detected signal. The rotation angle of the optical information recording medium 1 can be controlled via 88.

A predetermined light source driving current is supplied from the light source driving circuit 82 to the light sources in the pickup 11, the cure optical system 13, and the disk rotation angle detection optical system 14, and each light source emits a light beam with a predetermined light amount. Can do.

Further, the pickup 11 and the disc cure optical system 13 are provided with a mechanism capable of sliding the position in the radial direction of the optical information recording medium 1, and the position is controlled via the access control circuit 81.

By the way, the recording technology using the principle of angle multiplexing of holography tends to have a very small tolerance for the deviation of the reference beam angle.

Therefore, a mechanism for detecting the deviation amount of the reference beam angle is provided in the pickup 11, a servo control signal is generated by the servo signal generation circuit 83, and the deviation amount is corrected via the servo control circuit 84. It is necessary to provide a servo mechanism for this purpose in the optical information recording / reproducing apparatus 10.

Further, the pickup 11, the cure optical system 13, and the disk rotation angle detection optical system 14 may be simplified by combining several optical system configurations or all optical system configurations into one.

FIG. 3 shows a recording principle in an example of a basic optical system configuration of the pickup 11 in the optical information recording / reproducing apparatus 10. The light beam emitted from the light source 301 passes through the collimator lens 302 and enters the shutter 303. When the shutter 303 is open, after the light beam passes through the shutter 303, the optical ratio of the p-polarized light and the s-polarized light becomes a desired ratio by the optical element 304 composed of, for example, a half-wave plate. After the polarization direction is controlled, the light is incident on a PBS (Polarization Beam Splitter) prism 305.

The light beam that has passed through the PBS prism 305 functions as signal light 306, and after the light beam diameter is expanded by the beam expander 308, the light beam passes through the phase mask 309, the relay lens 310, and the PBS prism 311 and passes through the spatial light modulator 312. Is incident on.

The signal light to which information is added by the spatial light modulator 312 reflects the PBS prism 311 and propagates through the relay lens 313 and the spatial filter 314. Thereafter, the signal light is condensed on the optical information recording medium 1 by the objective lens 315.

On the other hand, the light beam reflected from the PBS prism 305 functions as reference light 307 and is set to a predetermined polarization direction according to recording or reproduction by the polarization direction conversion element 316 and then galvano- lated via the mirror 317 and the mirror 318. Incident on the mirror 319. Since the angle of the galvanometer mirror 319 can be adjusted by the actuator 320, the incident angle of the reference light incident on the optical information recording medium 1 after passing through the lens 321 and the lens 322 can be set to a desired angle. In order to set the incident angle of the reference light, an element that converts the wavefront of the reference light may be used instead of the galvanometer mirror.

In this way, the signal light and the reference light are incident on the optical information recording medium 1 so as to overlap each other, whereby an interference fringe pattern is formed in the recording medium, and information is recorded by writing this pattern on the recording medium. To do. In addition, since the incident angle of the reference light incident on the optical information recording medium 1 can be changed by the galvanometer mirror 319, recording by angle multiplexing is possible.

Hereinafter, in holograms recorded in the same area with different reference beam angles, holograms corresponding to each reference beam angle are called pages, and a set of pages angle-multiplexed in the same area is called a book. .

FIG. 4 shows a reproduction principle in an example of a basic optical system configuration of the pickup 11 in the optical information recording / reproducing apparatus 10. When reproducing the recorded information, the reference light is incident on the optical information recording medium 1 as described above, and the light beam transmitted through the optical information recording medium 1 is reflected by the galvanometer mirror 324 whose angle can be adjusted by the actuator 323. By doing so, the reproduction reference light is generated.

The reproduction light reproduced by the reproduction reference light propagates through the objective lens 315, the relay lens 313, and the spatial filter 314. Thereafter, the reproduction light passes through the PBS prism 311 and enters the photodetector 325, and the recorded signal can be reproduced. As the photodetector 325, for example, an image sensor such as a CMOS image sensor or a CCD image sensor can be used. However, any element may be used as long as page data can be reproduced.

FIG. 5 is a diagram showing another configuration of the pickup 11. In FIG. 5, the light beam emitted from the light source 501 passes through the collimator lens 502 and enters the shutter 503. When the shutter 503 is open, after the light beam passes through the shutter 503, the optical element 504 configured by, for example, a half-wave plate or the like adjusts the light quantity ratio of p-polarized light and s-polarized light to a desired ratio. After the polarization direction is controlled, the light enters the PBS prism 505.

The light beam transmitted through the PBS prism 505 is incident on the spatial light modulator 508 via the PBS prism 507. The signal light 506 to which information is added by the spatial light modulator 508 is reflected by the PBS prism 507 and propagates through an angle filter 509 that passes only a light beam having a predetermined incident angle. Thereafter, the signal light beam is focused on the hologram recording medium 1 by the objective lens 510.

On the other hand, the light beam reflected from the PBS prism 505 acts as reference light 512, and is set to a predetermined polarization direction according to recording or reproduction by the polarization direction conversion element 519, and then passed through the mirror 513 and the mirror 514 to be a lens. 515 is incident. The lens 515 plays a role of condensing the reference light 512 on the back focus surface of the objective lens 510, and the reference light once condensed on the back focus surface of the objective lens 510 becomes parallel light again by the objective lens 510. Is incident on the hologram recording medium 1.

Here, the objective lens 510 or the optical block 521 can be driven, for example, in the direction indicated by reference numeral 520. By shifting the position of the objective lens 510 or the optical block 521 along the driving direction 520, the objective lens 510 and the objective lens can be driven. Since the relative positional relationship of the condensing points on the back focus surface 510 changes, the incident angle of the reference light incident on the hologram recording medium 1 can be set to a desired angle. Instead of driving the objective lens 510 or the optical block 521, the incident angle of the reference light may be set to a desired angle by driving the mirror 514 with an actuator.

In this way, by causing the signal light and the reference light to enter the hologram recording medium 1 so as to overlap each other, an interference fringe pattern is formed in the recording medium, and information is recorded by writing this pattern on the recording medium. . Further, by shifting the position of the objective lens 510 or the optical block 521 along the driving direction 520, the incident angle of the reference light incident on the hologram recording medium 1 can be changed, so that recording by angle multiplexing is possible.

When reproducing the recorded information, the reference light is incident on the hologram recording medium 1 as described above, and the light beam transmitted through the hologram recording medium 1 is reflected by the galvanometer mirror 516 so that the reproduction reference light is reflected. Generate. The reproduction light reproduced by the reproduction reference light propagates through the objective lens 510 and the angle filter 509. Thereafter, the reproduction light passes through the PBS prism 507 and enters the photodetector 518, and the recorded signal can be reproduced.

The optical system shown in FIG. 5 has an advantage that the size can be greatly reduced by making the signal light and the reference light incident on the same objective lens as compared with the optical system configuration shown in FIG.

FIG. 6 shows an operation flow of recording and reproduction in the optical information recording / reproducing apparatus 10. Here, a flow relating to recording / reproduction using holography in particular will be described.

FIG. 6A shows an operation flow from when the optical information recording medium 1 is inserted into the optical information recording / reproducing apparatus 10 until preparation for recording or reproduction is completed, and FIG. FIG. 6C shows an operation flow until information is recorded on the information recording medium 1, and FIG. 6C shows an operation flow until the information recorded on the optical information recording medium 1 is reproduced from the ready state.

When a medium is inserted as shown in FIG. 6A, the optical information recording / reproducing apparatus 10 discriminates whether or not the inserted medium is a medium for recording or reproducing digital information using holography, for example ( 601).

As a result of disc discrimination, when it is determined that the optical information recording medium records or reproduces digital information using holography, the optical information recording / reproducing apparatus 10 reads control data provided on the optical information recording medium (602). ), For example, information relating to the optical information recording medium and information relating to various setting conditions during recording and reproduction, for example.

After reading out the control data, various adjustments according to the control data and learning processing (603) related to the pickup 11 are performed, and the optical information recording / reproducing apparatus 10 is ready for recording or reproduction (604).

As shown in FIG. 6B, the operation flow from the ready state to recording information is as follows. First, data to be recorded is received (611), and information corresponding to the data is received from the spatial light modulator in the pickup 11. Send to.

Thereafter, various recording learning processes such as optimization of the power of the light source 301 and optimization of exposure time by the shutter 303 are performed in advance so that high-quality information can be recorded on the optical information recording medium (612). ).

Thereafter, in the seek operation (613), the access control circuit 81 is controlled to position the pickup 11 and the cure optical system 13 at predetermined positions on the optical information recording medium. When the optical information recording medium 1 has address information, it reproduces the address information, checks whether it is positioned at the target position, and calculates the amount of deviation from the predetermined position if it is not positioned at the target position. And repeat the positioning operation.

Thereafter, a predetermined region is pre-cured using the light beam emitted from the cure optical system 13 (614), and data is recorded using the reference light and signal light emitted from the pickup 11 (615).

After recording the data, post cure is performed using the light beam emitted from the cure optical system 13 (616). Data may be verified as necessary.

As shown in FIG. 6C, the operation flow from the ready state to the reproduction of recorded information is as follows. First, in the seek operation (621), the access control circuit 81 is controlled, and the pickup 11 and the reproduction reference light are reproduced. The position of the optical system 12 is positioned at a predetermined position on the optical information recording medium. When the optical information recording medium 1 has address information, it reproduces the address information, checks whether it is positioned at the target position, and calculates the amount of deviation from the predetermined position if it is not positioned at the target position. And repeat the positioning operation.

Thereafter, reference light is emitted from the pickup 11, information recorded on the optical information recording medium is read (622), and reproduction data is transmitted (613).

FIG. 9 shows a data processing flow at the time of recording and reproduction. FIG. 9A shows the two-dimensional data on the spatial light modulator 312 after the recording data receiving process 611 in the input / output control circuit 90. FIG. 9B shows a recording data processing flow in the signal generation circuit 86 until conversion. FIG. 9B shows the process up to the reproduction data transmission processing 624 in the input / output control circuit 90 after the two-dimensional data is detected by the photodetector 325. The reproduction data processing flow in the signal processing circuit 85 is shown.

The data processing during recording will be described with reference to FIG. When user data is received (901), it is divided into a plurality of data strings, and each data string is converted to CRC (902) so that error detection at the time of reproduction can be performed. In order to prevent repetition, the data string is scrambled (903) to add a pseudo random number data sequence, and then error correction coding (904) such as Reed-Solomon code is performed so that error correction can be performed during reproduction. Next, the data string is converted into M × N two-dimensional data, and the two-dimensional data (905) for one page is configured by repeating the data for one page data. A marker serving as a reference for image position detection and image distortion correction at the time of reproduction is added to the two-dimensional data thus configured (906), and the data is transferred to the spatial light modulator 312 (907).

Next, the data processing flow during reproduction will be described with reference to FIG. The image data detected by the photodetector 325 is transferred to the signal processing circuit 85 (911). Image position is detected based on the marker included in the image data (912), distortion such as image tilt, magnification, distortion, etc. is corrected (913), and then binarization processing (914) is performed to remove the marker. (915) to acquire (916) two-dimensional data for one page. After converting the two-dimensional data obtained in this way into a plurality of data strings, error correction processing (917) is performed to remove the parity data strings. Next, descrambling processing (918) is performed, CRC error detection processing (919) is performed and CRC parity is deleted, and then user data is transmitted (920) via the input / output control circuit 90.

FIG. 7 is a block diagram of the signal generation circuit 86 of the optical information recording / reproducing apparatus 10.

When the input of user data to the output control circuit 90 is started, the input / output control circuit 90 notifies the controller 89 that the input of user data has started. In response to this notification, the controller 89 instructs the signal generation circuit 86 to record data for one page input from the input / output control circuit 90. A processing command from the controller 89 is notified to the sub-controller 701 in the signal generation circuit 86 via the control line 708. Upon receiving this notification, the sub-controller 701 controls each signal processing circuit via the control line 708 so that the signal processing circuits are operated in parallel. First, the memory control circuit 703 is controlled to store user data input from the input / output control circuit 90 via the data line 709 in the memory 702.

When the user data stored in the memory 702 reaches a certain amount, the CRC calculation circuit 704 performs control to convert the user data into CRC. Next, the scramble circuit 705 scrambles the CRC-converted data to add a pseudo-random data sequence, and the error correction encoding circuit 706 performs error correction encoding to add the parity data sequence. Finally, the pickup interface circuit 707 reads out the error correction encoded data from the memory 702 in the order of the two-dimensional data on the spatial light modulator 312 and adds a reference marker at the time of reproduction. The two-dimensional data is transferred to the spatial light modulator 312.

FIG. 8 is a block diagram of the signal processing circuit 85 of the optical information recording / reproducing apparatus 10.

When the photodetector 325 in the pickup 11 detects the image data, the controller 89 instructs the signal processing circuit 85 to reproduce the data for one page input from the pickup 11. A processing command from the controller 89 is notified to the sub-controller 801 in the signal processing circuit 85 via the control line 811. Upon receiving this notification, the sub-controller 801 controls each signal processing circuit via the control line 811 so that the signal processing circuits are operated in parallel.

First, the memory control circuit 803 is controlled to store the image data input from the pickup 11 via the pickup interface circuit 810 via the data line 812 in the memory 802. When the data stored in the memory 802 reaches a certain amount, the image position detection circuit 809 performs control to detect a marker from the image data stored in the memory 802 and extract an effective data range. Next, the image distortion correction circuit 808 performs distortion correction such as image inclination, magnification, and distortion by using the detected marker, and controls to convert the image data into the expected two-dimensional data size. Each bit data of a plurality of bits constituting the size-converted two-dimensional data is binarized by the binarization circuit 807 to determine “0” or “1”, and the data is arranged on the memory 802 in the order of the output of the reproduction data. Control to store. Next, the error correction circuit 806 corrects the error included in each data string, the scramble release circuit 805 releases the scramble to add the pseudo random number data string, and then the CRC calculation circuit 804 causes an error in the user data on the memory 802. Check not included. Thereafter, user data is transferred from the memory 802 to the input / output control circuit 90.

Here, the image distortion correction circuit 808 will be described in detail. FIG. 1 is a block diagram of an image distortion correction circuit according to the first embodiment of the present invention. Reference numeral 809 denotes an image detection circuit, 808 denotes an image distortion correction circuit, 807 denotes a binarization circuit, 101 denotes a page division circuit that divides page data into arbitrary units, and 102 denotes a time when an image obtained by oversampling is recorded. Oversampling cancellation circuit that adjusts the signal so that it becomes a one-to-one relationship, 103 is a shift amount detection circuit that detects the shift amount in the horizontal and vertical directions, 104 is an AGC circuit that normalizes the brightness range, and 105 is the brightness A luminance detection circuit 106 that detects the amount, and a page combination circuit 106 that combines the divisions in arbitrary units and returns them to page data.

Next, an operation flowchart in the image distortion correction circuit will be described with reference to FIG. The effective data obtained by the image position detection circuit 809 performs image distortion correction using the detected marker. FIG. 11 shows an example of page data. It is assumed that the data of one page 1101 is divided in units of subpages 1102, and at least one marker 1103 as a known pattern is placed on each subpage. Here, the marker 1103 is composed of, for example, 16 × 16 pixels, and information on the target level of the brightness of this marker, that is, the average of the brightness of each pixel constituting the marker (hereinafter referred to as the average brightness of the marker). May be stored in a memory in the optical information recording / reproducing apparatus.

Of course, the present invention is not limited to the case of 16 × 16 pixels. Further, the ON / OFF ratio of the marker may be determined in advance according to a standard or the like. In this case, the optical information recording / reproducing apparatus can easily detect the average luminance of the marker 1103.

In the image distortion correction circuit 808, first, the page division circuit 101 divides a page into subpages 1102 (1601).

Next, the shift amount detection circuit 103 detects a shift amount such as a horizontal and vertical position shift, a rotation shift, and a magnification shift in each subpage using a marker, and the oversampling cancel circuit 102 is based on the shift amount. Thus, one pixel in the page is adjusted to have a one-to-one correspondence with either the ON or OFF signal in the spatial light modulator 312 during recording (1602). This is because the resolution of the photodetector 325 is usually higher than the resolution of the spatial light modulator 312 in order to ensure sufficient reproduction performance even when there is a page misalignment. As a method for detecting misalignment, for example, a known pattern is embedded in the marker. Therefore, it is possible to cope with this by performing pattern matching with a desired pattern and generating a position error.

Next, the luminance detection circuit 105 detects the average luminance of the marker as a known pattern for each subpage, and the AGC circuit 104 performs normalization of the luminance range, adjustment of the offset, and the like, whereby the amplitude of the luminance of each subpage. The process is performed so that each reaches the target level (1603). Note that the target level value may be held by the optical information reproducing apparatus, or the target level value may be held in the optical information recording medium. Further, the amplitude of the luminance of each subpage may be constant at the target level by setting the maximum amplitude of the subpages or the average luminance of the markers of each subpage as the target level. In this way, by making the luminance of each subpage constant over the entire page, the entire book, or the entire medium, the dynamic range can be effectively utilized in the subsequent calculation processing.

FIG. 10 is an example of a histogram of image data. Ideally, the majority of OFF pixels gather at a value of 1 (μ0) and the majority of ON pixels at a value of 2 (μ1), and a clear separation is seen. By correcting the value of the brightness level or the range of the brightness spread by the AGC process, for example, when brightness unevenness appears as a change in brightness amplitude, the correction by the AGC process becomes effective.

Thereafter, page unit data is generated by the page combination circuit 106 (1604), and the data is output to the binarization circuit 807. In the binarization circuit 807, calculation is performed using maximum likelihood decoding or the like, and two-dimensional data for one page from which the marker is removed is acquired.

According to the present embodiment, it is possible to reduce luminance unevenness generated in units of pages and improve reproduction performance.

Further, since the marker used for canceling oversampling can be diverted from the brightness information used for AGC processing, it is not necessary to embed dedicated data in page unit data, so that data capacity can be prevented from being reduced. Furthermore, since it does not depend on the modulation rule constituting the data in the page, AGC processing can be configured without limiting the signal processing method.

In this embodiment, only the average brightness of the marker has been described. However, even if the average brightness is calculated for the entire sub-page including the marker, the same processing can be performed, and processing by sub-page unit reduces the overall variation. It is possible to correct appropriately without being affected. This also applies to the following embodiments.

Also, by limiting the luminance range by AGC processing, it is also possible to limit the calculation range in the subsequent calculation processing, thereby suppressing an increase in circuit scale.

Further, for example, by using the configuration shown in FIG. 21, AGC processing for each divided region can be performed in parallel, and signal reproduction can be speeded up.

In this embodiment, the binary example of the OFF pixel and the ON pixel is shown. However, the present invention is not limited to this, and the present invention can be applied even in the case of three or more values.

In addition, when oversampling processing is not performed, an oversampling cancel circuit is not necessary. The same applies to the following embodiments.

FIG. 12 is a block diagram of an image distortion correction circuit according to the second embodiment of the present invention. An AGC determination circuit 1201 for determining whether or not the AGC process is performed is provided, and the other components are the same as those in FIG.

An operation flowchart in the image distortion correction circuit will be described with reference to FIG. The effective data obtained by the image position detection circuit 809 performs image distortion correction using the detected marker. In the image distortion correction circuit 808, first, the page division circuit 101 divides a page into subpages 1102 (1701).

Next, the shift amount detection circuit 103 detects a shift amount such as a horizontal and vertical position shift, a rotation shift, and a magnification shift in each subpage using a marker, and the oversampling cancel circuit 102 is based on the shift amount. Thus, one pixel in the page is adjusted to have a one-to-one correspondence with either the ON or OFF signal in the spatial light modulator 312 during recording (1702).

Next, the luminance detection circuit 105 detects the average luminance of the marker as a known pattern for each subpage. Next, in the AGC determination circuit 1201, by comparing the average luminance in each sub-page with the desired luminance, for example, only the sub-page that seems to cause steep luminance unevenness, the sub-page that performs AGC processing And the presence / absence of AGC processing are determined (1703). Therefore, only for the subpages determined to have AGC processing, the AGC circuit 104 performs normalization of the luminance range and adjustment of the offset so that the luminance amplitude of each subpage becomes constant. (1704).

Thereafter, page unit data is generated by the page combination circuit 106 (1705), and the data is output to the binarization circuit 807. In the binarization circuit 807, calculation is performed using maximum likelihood decoding or the like, and two-dimensional data for one page from which the marker is removed is acquired.

According to the present embodiment, the same effect as in the first embodiment can be obtained. In addition, since the number of subpages subjected to AGC processing can be limited, the number of processing operations can be reduced and processing can be performed at high speed.

FIG. 13 is a block diagram of an image distortion correction circuit according to the third embodiment of the present invention. A memory 1301 is included, and the others are the same as those in FIG.

The operation will be described with reference to an operation flowchart in the image distortion correction circuit of FIG. The effective data obtained by the image position detection circuit 809 performs image distortion correction using the detected marker. In the image distortion correction circuit 808, first, the page dividing circuit 101 divides a page into subpages 1102 (2001). Next, the shift amount detection circuit 103 detects a shift amount such as a horizontal and vertical position shift, a rotation shift, and a magnification shift in each subpage using a marker, and the oversampling cancel circuit 102 is based on the shift amount. Thus, one pixel in the page is adjusted to have a one-to-one correspondence with either the ON or OFF signal in the spatial light modulator 312 at the time of recording (2002).

Next, the brightness detection circuit 105 calculates the average brightness of the marker as a known pattern for each subpage. Next, in the AGC determination circuit 1201, by comparing the average luminance in each sub-page with the desired luminance, for example, only the sub-page that seems to cause steep luminance unevenness, the sub-page that performs AGC processing And whether or not AGC processing is performed is determined (2003). Further, by including the memory 1301 in the configuration of this embodiment, it is possible to store luminance unevenness information in units of pages. For example, the predicted value of AGC correction is stored from the luminance unevenness information when a page composed of one page known pattern is reproduced, the luminance unevenness information of the page at the previous page or the adjacent book position, and the like. AGC processing can be performed according to the value. Further, not only the luminance comparison of each subpage but also the luminance information of peripheral subpages may be combined to determine the presence / absence of AGC processing for the subpage.

Therefore, normalization of the luminance range and adjustment of the offset are performed only for the subpage determined to have AGC processing, so that the processing is performed so that the luminance amplitude of the subpage becomes the target level. Implement (1704).

Thereafter, page unit data is generated by the page combination circuit 106 (1705), and the data is output to the binarization circuit 807. In the binarization circuit 807, calculation is performed using maximum likelihood decoding or the like, and two-dimensional data for one page from which the marker is removed is acquired.

According to the present embodiment, the same effect as in the second embodiment can be obtained. Moreover, since the subpage to be AGC processed can be limited by the predicted value, the number of processing operations can be reduced and processing can be performed at high speed.

FIG. 14 is a block diagram of an image distortion correction circuit according to the fourth embodiment of the present invention. It has a first page dividing circuit 1401 and a second page dividing circuit 1402 that divide page data into arbitrary units, an adaptive equalization circuit 1403 that performs adaptive control and equalization processing, and the others are the same as FIG. is there.

An operation flowchart in the image distortion correction circuit will be described with reference to FIG. The effective data obtained by the image position detection circuit 809 performs image distortion correction using the detected marker. In the image distortion correction circuit 808, first, the first page division circuit 1401 divides a page into subpage 1102 units (for example, m division) (1801).

Next, the shift amount detection circuit 103 detects a shift amount such as a horizontal and vertical position shift, a rotation shift, and a magnification shift in each subpage using a marker, and the oversampling cancel circuit 102 is based on the shift amount. Thus, one pixel in the page is adjusted so as to have a one-to-one correspondence with either the ON or OFF signal in the spatial light modulator 312 during recording (1802).

Next, the brightness detection circuit 105 calculates the average brightness of the marker as a known pattern for each subpage. Next, in the AGC determination circuit 1201, by comparing the average luminance in each sub-page with the desired luminance, for example, only the sub-page that seems to cause steep luminance unevenness, the sub-page that performs AGC processing And whether AGC processing is present or not is determined (1803).

In addition, since the memory 1301 can store brightness unevenness information in units of pages, the brightness unevenness information when a page composed of one page known pattern is reproduced, the previous page, and the adjacent book position. A predicted value of AGC correction can be stored from the luminance unevenness information of the page at AGC, and the AGC process can be performed according to the predicted value. Therefore, normalization of the luminance range and adjustment of the offset are performed only for the subpage determined to have AGC processing, so that the processing is performed so that the luminance amplitude of the subpage becomes the target level. Implement (1804). Next, the second page division circuit 1402 integrates the divided subpages and re-divides them into subpage 1102 units (m division equivalent to the first page division circuit) or multiple subpages 1102 units (for example, n divisions). Division is performed (1805). Since the inter-pixel response differs for each area in the page due to various disturbances (angular deviation, wavelength deviation, aberration, etc.), the area is divided and the filter coefficient is calculated for each area, and adaptive using that coefficient By performing the equalization processing on (1806), it is possible to further improve the reproduction performance of the entire page. Thereafter, the page combination circuit 106 generates data in units of pages (1807), and the data is output to the binarization circuit 807. In the binarization circuit 807, calculation is performed using maximum likelihood decoding or the like, and two-dimensional data for one page from which the marker is removed is acquired.

According to the present embodiment, the same effect as in the third embodiment can be obtained. In addition, since the adaptive equalization process is performed after the AGC process is performed, the range of calculation when calculating the filter coefficient during the adaptive equalization process can be limited, and the number of divided areas during the adaptive equalization can be reduced. However, since the effect can be easily obtained, the number of processing operations and the number of parallel processing operation circuits can be reduced, and the circuit scale can be reduced. In addition, the number of divisions in the second page division circuit 1402 can be switched based on the result of the AGC determination circuit 1201, and adaptive equalization processing can be performed in an appropriate region division according to the variation in luminance. Furthermore, in the present embodiment, the adaptive equalization circuit 1403 performs the adaptive equalization process after the AGC process by the AGC circuit 1403. However, the adaptive equalization circuit 1403 uses the luminance information of the luminance detection circuit 105. This can also be realized in the same way as a configuration for correcting the filter coefficient calculation.

In step 1805, the process of integrating the divided subpages is performed. However, the re-division may be performed without performing the process of integrating.

FIG. 15 is a block diagram of an image distortion correction circuit according to the fifth embodiment of the present invention. The position of the AGC circuit 1501 is in front of the oversampling cancellation circuit 102, and the other parts are the same as in FIG.

An operation flowchart in the image distortion correction circuit will be described with reference to FIG. The effective data obtained by the image position detection circuit 809 performs image distortion correction using the detected marker. In the image distortion correction circuit 808, first, the first page division circuit 1401 divides a page into subpage 1102 units (for example, m division) (1901). Next, processing is performed in the AGC circuit 1501 so that the luminance amplitude of each sub-page becomes a target level (1903). Next, the shift amount detection circuit 103 detects a shift amount such as a horizontal and vertical position shift, a rotation shift, and a magnification shift in each subpage using a marker, and the oversampling cancel circuit 102 is based on the shift amount. Thus, one pixel in the page is adjusted so as to have a one-to-one correspondence with either the ON or OFF signal in the spatial light modulator 312 during recording (1904).

Next, the brightness detection circuit 105 calculates the average brightness of the marker as a known pattern for each subpage. Next, the sub-page that requires AGC processing is selected from the calculated average luminance information, the presence / absence of AGC processing is determined, and luminance unevenness information is stored in the memory 1301 as necessary. This memory 1301 can also be stored as a predicted value for AGC correction. As described above, it is possible to determine the presence / absence of the AGC process in the AGC circuit 1501 in the previous stage from the luminance unevenness information in the previous page and adjacent positions, and to control the AGC process on the page (1902). Next, in the second page division circuit 1402, re-division is performed in units of subpage 1102 (m division equivalent to the first page division circuit) or in units of a plurality of subpages 1102 (for example, n division) (1905). Since the inter-pixel response differs for each area in the page due to various disturbances (angular deviation, wavelength deviation, aberration, etc.), the area is divided and the filter coefficient is calculated for each area, and adaptive using that coefficient By performing the equalization process (1906), the reproduction performance of the entire page can be further improved. Thereafter, the page combination circuit 106 generates page unit data (1907), and the data is output to the binarization circuit 807. In the binarization circuit 807, calculation is performed using maximum likelihood decoding or the like, and two-dimensional data for one page from which the marker is removed is acquired.

According to the present embodiment, the same effect as in the third embodiment can be obtained. In addition, since oversampling cancellation processing and adaptive equalization processing are performed after performing AGC processing, the range of calculation at the time of filter coefficient calculation at the time of calculation by pattern matching etc. at the time of oversampling cancellation and adaptive equalization processing The circuit scale can be reduced by reducing the number of processing operations. In addition, the number of divisions in the second page division circuit 1402 can be switched based on the result of the AGC determination circuit 1201, and adaptive equalization processing can be performed in an appropriate region division according to the variation in luminance. Further, the configuration can be similarly realized by correcting the filter coefficient calculation in the adaptive equalization circuit 1403 using the luminance information of the luminance detection circuit 105.

In addition, this invention is not limited to the above-mentioned Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

Further, in the present embodiment so far, the AGC circuit has been described as the circuit for correcting the luminance. However, the circuit is not particularly limited to the AGC circuit as long as the circuit can obtain the same effect.

Also, the control lines and information lines indicate what is considered necessary for the explanation, and not all the control lines and information lines on the product are necessarily shown. Actually, it may be considered that almost all the components are connected to each other.

In the above-described embodiments, the angle multiplexing method has been described as an example. However, the present invention is not limited to this, and can be applied to a shift multiplexing method or the like, and is applicable to reproducing a two-dimensional signal from an optical information recording medium. I can do it.

DESCRIPTION OF SYMBOLS 1 ... Optical information recording medium, 10 ... Optical information recording / reproducing apparatus, 11 ... Pickup,
12 ... Reference light optical system for reproduction, 13 ... Disc Cure optical system,
14 ... Optical system for detecting disk rotation angle, 81 ... Access control circuit,
82... Light source drive circuit, 83... Servo signal generation circuit,
84 ... Servo control circuit, 85 ... Signal processing circuit, 86 ... Signal generation circuit,
87 ... Shutter control circuit, 88 ... Disc rotation motor control circuit,
89 ... Controller, 90 ... Input / output control circuit, 91 ... External control device,
301 ... light source, 303 ... shutter, 306 ... signal light, 307 ... reference light,
308 ... Beam expander, 309 ... Phase mask
310 ... relay lens, 311 ... PBS prism,
312 ... Spatial light modulator, 313 ... Relay lens, 314 ... Spatial filter,
315 ... objective lens, 316 ... polarization direction conversion element, 320 ... actuator,
321 ... lens, 322 ... lens, 323 ... actuator,
324 ... Mirror, 325 ... Photodetector 501 ... Light source, 502 ... Collimating lens, 503 ... Shutter, 504 ... Optical element,
505 ... PBS prism, 506 ... signal light, 507 ... PBS prism, 508 ... spatial light modulator,
509 ... Angle filter, 510 ... Objective lens, 511 ... Objective lens actuator,
512: reference beam, 513: mirror, 514 ... mirror, 515 ... lens,
516 ... Galvano mirror, 517 ... Actuator, 518 ... Photo detector,
519: Polarization direction conversion element, 520: Driving direction, 521: Optical block,
701 ... Sub-controller, 702 ... Memory, 703 ... Memory control circuit, 704 ... CRC arithmetic circuit,
705 ... scramble circuit, 706 ... error correction coding circuit,
707 ... Pickup interface circuit,
801 ... Sub-controller, 802 ... Memory, 803 ... Memory control circuit, 804 ... CRC arithmetic circuit,
805 ... descrambling circuit, 806 ... error correction circuit, 807 ... binarization circuit,
808 ... Image distortion correction circuit, 809 ... Image position detection circuit,
810: Pickup interface circuit,
101 ... Page division circuit, 102 ... Oversampling cancellation circuit, 103 ... Shift amount detection circuit,
104... AGC circuit, 105... Luminance detection circuit, 106.
1101 ... page, 1102 ... subpage, 1103 ... marker,
1201... AGC determination circuit, 1301.
1401... First page dividing circuit, 1402... Second page dividing circuit, 1403... Adaptive equalizing circuit,
1501 ... AGC circuit,
2101, 2102, 2103... AGC calculation unit

Claims (15)

An optical information reproducing device for reproducing information using holography,
A pickup for reproducing a two-dimensional signal from an optical information recording medium;
A dividing unit for dividing a two-dimensional signal reproduced from the pickup into m (m> 1) two-dimensional signal groups;
A luminance characteristic correcting unit that corrects the two-dimensional signal group output from the dividing unit to a predetermined luminance characteristic;
The data area constituted by the two-dimensional signal has a known pattern,
The optical information reproducing apparatus, wherein the luminance characteristic correction unit corrects luminance characteristics of the two-dimensional signal group based on the known pattern. The optical information reproducing apparatus according to claim 1,
The optical information reproducing apparatus, wherein the dividing unit divides each predetermined two-dimensional signal group having the known pattern. The optical information reproducing apparatus according to claim 1,
The luminance correction unit calculates luminance information in a known pattern in a two-dimensional signal group divided into predetermined size units, and corrects the luminance of the two-dimensional signal group using the luminance information. Optical information reproducing device. The optical information reproducing apparatus according to claim 1,
And a position correcting unit that corrects the two-dimensional signal group output from the dividing unit to a predetermined position.
The known pattern is a pattern for calculating distortion information from a two-dimensional signal reproduced from the pickup,
The position correction unit detects a position shift from the known pattern and corrects the position shift of the two-dimensional signal group;
The luminance correction unit calculates luminance information in the known pattern, and corrects the luminance of a two-dimensional signal group using the luminance information. The optical information reproducing apparatus according to claim 1,
An optical information reproducing apparatus comprising: a luminance correction determination unit that controls switching of the operation of the luminance correction unit. The optical information reproducing apparatus according to claim 5,
The luminance correction unit calculates luminance information in the known pattern in the two-dimensional signal group divided into predetermined size units,
The luminance correction determination unit switches the operation of the luminance correction unit according to the variation of the calculated luminance information. The optical information reproducing apparatus according to claim 5,
An optical information reproducing apparatus comprising a storage unit for storing switching control information for controlling switching of the operation of the luminance correction unit. The optical information reproducing apparatus according to claim 7,
The storage unit stores switching control information obtained from a previously reproduced two-dimensional signal,
The optical information reproducing apparatus, wherein the luminance correction determination unit switches an operation of correcting luminance characteristics to the next reproduced two-dimensional signal using the switching control information stored in the storage unit. An optical information reproducing device for reproducing information using holography,
A pickup for reproducing a two-dimensional signal from an optical information recording medium;
A first dividing unit that divides a two-dimensional signal reproduced from the pickup into m (m> 1) two-dimensional signal groups;
A luminance characteristic correction unit that corrects the two-dimensional signal group output from the first division unit to a predetermined luminance characteristic;
A second dividing unit that combines the two-dimensional signal groups output from the luminance correction unit and re-divides the combined two-dimensional signals into n (n> 1, m ≧ n) two-dimensional signal groups;
An adaptive equalization unit that equalizes the two-dimensional signal group output from the second division unit to a predetermined target characteristic,
The data area constituted by the two-dimensional signal has a known pattern,
A luminance characteristic correction unit corrects the luminance characteristic of the two-dimensional signal group based on the known pattern. The optical information reproducing apparatus according to claim 9, wherein
The luminance correction unit calculates luminance information in the two-dimensional signal group divided into predetermined size units, corrects the luminance of the two-dimensional signal group using the luminance information,
An optical information reproducing apparatus, wherein the number of divisions in the second division unit is switched according to luminance information of the luminance correction unit. An optical information reproducing device for reproducing information using holography,
A pickup for reproducing a two-dimensional signal from an optical information recording medium;
A first dividing unit that divides a two-dimensional signal reproduced from the pickup into m (m> 1) two-dimensional signal groups;
A unit that corrects the two-dimensional signal group output from the first dividing unit to a predetermined luminance characteristic;
A unit that corrects the two-dimensional signal group output from the luminance correction unit to a predetermined position;
A second dividing unit that combines the two-dimensional signal groups output from the position correction unit and subdivides the combined two-dimensional signals into n (n> 1, m ≧ n) two-dimensional signal groups;
An adaptive equalization unit that equalizes the two-dimensional signal group output from the second division unit to a predetermined target characteristic,
The data area constituted by the two-dimensional signal has a known pattern,
A luminance characteristic correction unit corrects the luminance characteristic of the two-dimensional signal group based on the known pattern. An optical information reproduction method for reproducing information using holography,
A reproducing step of reproducing a two-dimensional signal from the optical information recording medium;
A division step of dividing the two-dimensional signal obtained in the reproduction step into m (m> 1) two-dimensional signal groups;
A luminance correction step of correcting the two-dimensional signal group obtained in the dividing step to a predetermined luminance characteristic;
The data area constituted by the two-dimensional signal has a known pattern,
In the luminance correction step, the luminance characteristic of the two-dimensional signal group is corrected based on the known pattern. The optical information reproducing method according to claim 12, comprising:
An optical information reproducing method comprising a luminance correction determination step for controlling switching of operations in the luminance correction step. An optical information reproduction method for reproducing information using holography,
A reproducing step of reproducing a two-dimensional signal from the optical information recording medium;
A first dividing step of dividing the two-dimensional signal obtained in the reproducing step into m (m> 1) two-dimensional signal groups;
A luminance correction step of correcting the two-dimensional signal group obtained in the first division step to a predetermined luminance characteristic;
A second dividing step of combining the two-dimensional signal groups obtained in the luminance correction step and subdividing the combined two-dimensional signals into n (n> 1, m ≧ n) two-dimensional signal groups;
Equalizing the two-dimensional signal group obtained in the second dividing step to a predetermined target characteristic;
The data area constituted by the two-dimensional signal has a known pattern,
In the luminance correction step, the luminance characteristic of the two-dimensional signal group is corrected based on the known pattern.
A method for reproducing optical information, comprising: An optical information reproduction method for reproducing information using holography,
Reproducing a two-dimensional signal from the optical information recording medium;
A first dividing step of dividing the two-dimensional signal obtained in the reproducing step into m (m> 1) two-dimensional signal groups;
A luminance correction step of correcting the two-dimensional signal group obtained in the first division step to a predetermined luminance characteristic;
A position correction step of correcting the two-dimensional signal group obtained in the luminance correction step to a predetermined position;
A second dividing step of combining the two-dimensional signal groups obtained in the position correcting step and subdividing the combined two-dimensional signals into n (n> 1, m ≧ n) two-dimensional signal groups;
Equalizing the two-dimensional signal group obtained in the second dividing step to a predetermined target characteristic;
The data area constituted by the two-dimensional signal has a known pattern,
In the luminance correction step, the luminance characteristic of the two-dimensional signal group is corrected based on the known pattern.
A method for reproducing optical information, comprising:

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