Patent Application
20170270961
Technical Field
The present invention relates to a device and method for reproducing information from an optical information storage medium using holography.
Related Art
As a method for improving quality of a reproduction signal from a holographic memory, Abstract of JP 2008-536158 A discloses a method for processing data pixels in a holographic data storage system. Abstract of JP 2008-536158 A further discloses that the method includes assigning predetermined reserved blocks throughout each data page, where each reserved block comprises known pixel patterns, determining position errors of the data page by computing the best match between regions of the data page and the predetermined reserved blocks, and compensating the data pixels at the detector in accordance with the corresponding position errors of the data page.
As a technique for correcting an erroneously detected marker in reproduction of a hologram, for example, Abstract of WO 2013/150565 A discloses that an optical information reproducing device includes a detection unit that detects the position information of a marker as a well-known pattern, a detection error position estimating unit that estimates presence/absence of detection error in the position information of the marker and estimates the position where the detection error occurs if there is detection error, a position correcting unit that corrects the marker position information of the detection error position specified by the detection error position estimating unit, and a signal detection unit that detects each signal from within the page based on the corrected marker position information.
As a technique for improving quality of a reproduction image, JP 2008-536158 A discloses a technique for compensating a distortion or a position shift of the reproduction image using a known pixel pattern included in page data.
Furthermore, WO 2013/150565 A discloses a technique for determining, when quality of a reproduction image is poor and a known pattern is erroneously detected, the erroneous detection and for correcting marker information on the erroneously detected part based on peripheral known pattern information.
At this time, when a nonlinear distortion occurs in a reproduction image, a known pattern disposed in page data cannot be detected. JP 2008-536158 A and WO 2013/150565 A do not mention the case in which a distortion, such as a nonlinear distortion, occurs and a known pattern cannot be detected.
Thus, a purpose of the present invention is to detect a known pattern according to a nonlinear distortion occurring in a reproduction image and to improve quality of a reproduction signal.
The above problem is to be solved by, for example, the invention disclosed in claims.
According to embodiments of the present invention, it is possible to detect a marker by marker position estimation in which a distortion amount is estimated even in an image having a distortion which interferes with marker detection, and to improve quality of a reproduction signal.
Hereinafter, embodiments of the present invention are described with reference to the drawings.
An optical information recording/reproducing device 10 is connected with an external control device 91 through an input/output control circuit 90. When recording information, the optical information recording/reproducing device 10 receives an information signal to be recorded from the external control device 91 with the input/output control circuit 90. When reproducing information, the optical information recording/reproducing device 10 transmits a reproduced information signal to the external control device 91 with the input/output control circuit 90.
The optical information recording/reproducing device 10 includes a pickup 11, a reproducing reference beam optical system 12, a cure optical system 13, a disc rotation angle detecting optical system 14, and a rotating motor 50, and an optical information storage medium 1 is configured so as to be rotated by the rotating motor 50.
The pickup 11 exposes the optical information storage medium 1 to a reference beam and a signal beam, and records digital information in the optical information storage medium 1 using holography. At this time, an information signal to be recorded is transmitted to a spatial light modulator in the pickup 11 through a signal generation circuit 86 by a controller 89, and the signal beam is modulated by the spatial light modulator.
When information recorded in the optical information storage medium 1 is reproduced, the reproducing reference beam optical system 12 generates a light wave which causes a reference beam emitted from the pickup 11 to enter the optical information storage medium 1 in the opposite direction from the direction at the time of recording. A light detector, which is described later, in the pickup 11 detects a recovered beam to be reproduced with a reproducing reference beam, and a signal processing circuit 85 reproduces a signal.
The exposure time of the optical information storage medium 1 exposed to the reference beam and the signal beam can be adjusted by controlling an opening/closing time of a shutter in the pickup 11 by the controller 89 through a shutter control circuit 87.
The cure optical system 13 generates a light beam used for pre-curing and post-curing the optical information storage medium 1. The pre-curing is pre-processing in which a desired position in the optical information storage medium. 1 is exposed to a predetermined light beam before the desired position is exposed to the reference beam and the signal beam when information is recorded in the desired position. The post-curing is post-processing in which the desired position in the optical information storage medium 1 is exposed to a predetermined light beam so that further information is not added in the desired position after the information is recorded in the desired position.
The disc rotation angle detecting optical system 14 detects a rotation angle of the optical information storage medium 1. When the optical information storage medium 1 is adjusted to a predetermined rotation angle, the disc rotation angle detecting optical system 14 detects a signal according to a rotation angle, and the controller 89 controls the rotation angle of the optical information storage medium 1 through a disc rotating motor control circuit 88 using the detected signal.
A light source drive circuit 82 supplies a predetermined light source drive current to the light sources in the pickup 11, the cure optical system 13, and the disc rotation angle detecting optical system 14, and each light source emits alight beam at a predetermined amount of light.
Furthermore, the pickup 11 and the cure optical system 13 each have a mechanism with which the position can be slid in a radial direction of the optical information storage medium 1, and the position control is performed through an access control circuit 81.
Incidentally, a recording technique using a principle of angle multiplexing of holography tends to have an extremely small permissible error to a shift of a reference beam angle.
Thus, a servo mechanism needs to be provided in the optical information recording/reproducing device 10 to correct, through a servo control circuit 84, a shift amount of the reference beam angle, which is detected by a mechanism provided in the pickup 11, using a servo controlling signal generated by a servo signal generation circuit 83.
Note that, in the pickup 11, the cure optical system 13, and the disc rotation angle detecting optical system 14, some or all of optical system configurations may be simplified by being integrated into one.
The light beam passing through the PBS prism 305 serves as a signal beam 306, passes through a beam expander 308 to expand the light beam diameter, then, passes through a phase mask 309, a relay lens 310, and a PBS prism 311, and enters the spatial light modulator 312.
The signal beam to which information is added by the spatial light modulator 312 is reflected by the PBS prism 311, and passes through a relay lens 313 and an aperture 314. Thereafter, the signal beam is condensed on the optical information storage medium 1 by an objective lens 315.
On the other hand, the light beam reflected by the PBS prism 305 serves as a reference beam 307, passes through a polarization direction conversion element 316 to set the direction in a predetermined polarization direction according to the time of recording or reproducing, and enters a galvano mirror 319 through a mirror 317 and a mirror 318. Since the angle of the galvano mirror 319 can be adjusted by an actuator 320, the angle of incidence of the reference beam entering the optical information storage medium 1 after passing through a lens 321 and a lens 322 can be set to a desired angle. Note that, to set the angle of incidence of the reference beam, an element which converts a wavefront of the reference beam may be used instead of the galvano mirror.
By causing the signal beam and the reference beam to enter the optical information storage medium 1 so as to be superimposed on each other in this manner, an interference pattern is formed in the optical information storage medium 1, and the pattern is written in the optical information storage medium 1 to record the information. Furthermore, since the angle of incidence of the reference beam entering the optical information storage medium 1 can be changed by the galvano mirror 319, it is possible to perform angular multiplexing recording.
Hereinafter, in a hologram recorded in the same area by changing reference beam angles, a hologram corresponding to each reference beam angle is referred to as a page, and a set of pages angular-multiplexed in the same area is referred to as a book.
The recovered beam reproduced with the reproducing reference beam passes through the objective lens 315, the relay lens 313, and the aperture 314. Thereafter, the recovered beam passes through the PBS prism. 311, and enters the light detector 325, and the recorded signal can be reproduced. As the light detector 325, an imaging element, such as a CMOS image sensor or a CCD image sensor, can be used, and any element may be used as long as page data can be reproduced.
As shown in
As a result of the disc determination, when it is determined that the optical information storage medium 1 contains the digital information which is recorded or reproduced using holography, the optical information recording/reproducing device 10 reads control data in the optical information storage medium 1 (S503), and acquires, for example, information on the optical information storage medium 1 or information on various setting conditions at the time of recording or reproducing.
By performing various adjustments according to the control data and learning processing related to the pickup 11 (S504), the optical information recording/reproducing device 10 is ready for recording or reproducing (S505).
As shown in
Thereafter, to record high-quality information in the optical information storage medium 1, various types of learning processing for recording, such as the power optimization of the light source 301 or the optimization of the exposure time by the shutter 303, is appropriately performed in advance (S512).
Thereafter, in a seek operation (S513), the light beams emitted from the pickup 11 and the cure optical system 13 are positioned to a predetermined position on the optical information storage medium 1 by controlling the access control circuit 81. When the optical information storage medium 1 has address information, it is confirmed that they are positioned at the desired position by reproducing the address information. If they are not positioned at the desired position, the shift amount from the predetermined position is calculated and the positioning is repeated.
Thereafter, the predetermined area is pre-cured using the light beam emitted from the cure optical system 13 (S514), and the data is recorded using the reference beam and the signal beam which are emitted from the pickup 11 (S515).
After the data is recoded, the post-curing is performed using the light beam emitted from the cure optical system 13 (S516). The data may be verified as needed.
As shown in
Thereafter, the reference beam is emitted from the pickup 11, the information recorded in the optical information storage medium 1 is read (S522), and the reproduced data is transmitted (S523).
Next, with reference to
First, with reference to
When the input of the user data to the input/output control circuit 90 is started, the input/output control circuit 90 notifies the controller 89 that the input of the user data is started. The controller 89 instructs, in response to the notification, the signal generation circuit 86 to record one page of data input from the input/output control circuit 90.
When the signal generation circuit 86 receives the user data (S801), the processing instruction from the controller 89 is notified to a sub-controller 601 in the signal generation circuit 86 through a control line 609.
The sub-controller 601 controls, in response to the notification, all signal processing circuits through the control line 609 so that the signal processing circuits operate in parallel.
A memory control circuit 603 controls a memory 602 so as to store, through a data line 610, the user data input from the input/output control circuit 90.
When the user data stored in the memory 602 reaches a certain amount, a CRC operation circuit 604 divides the user data into a plurality of data sequences and performs CRC coding to each data sequence to perform error detection at the time of reproducing (S802).
A scramble circuit 605 performs scrambling in which a pseudo-random number data sequence is added to the data sequence, to which the CRC cording is performed, in order to prevent the repetition of the same pattern by equalizing the number of on-pixels with the number of off-pixels (S803).
An error correction coding circuit 606 performs error correction coding in which a parity data sequence such as Reed-Solomon coding is added in order to perform error correction at the time of reproducing (S804).
A pickup interface circuit 608 converts the data sequence into M×N two-dimensional data, and generates one page of two-dimensional data by repeating the conversion for one page of data (S805), adds, to the generated two-dimensional data, a marker which serves as a criterion for image position detection or for image distortion correction at the time of reproducing (S806), and transfers the data to the spatial light modulator 312 (S807).
Next, with reference to
When the light detector 325 in the pickup 11 detects image data (S901), the controller 89 instructs the signal processing circuit 85 to reproduce one page of data input from the pickup 11.
The processing instruction from the controller 89 is notified to a sub-controller 701 in the signal processing circuit 85 through a control line 712. The sub-controller 701 controls, in response to the notification, all signal processing circuits through a control line 712 so that the signal processing circuits operate in parallel.
A memory control circuit 703 controls a memory 702 so as to store, through a data line 713, image data input from the pickup 11 through a pickup interface circuit 711.
A distortion learning circuit 101 learns a distortion amount of a reproduction image based on the data stored in the memory 702 (S902).
When the data stored in the memory 702 reaches a certain amount, an image position detection circuit 710 detects, based on the distortion amount calculated by the distortion learning circuit 101, the marker from the image data stored in the memory 702, and detects the image position based on the marker position (S903).
An image distortion correction circuit 709 performs distortion correction to the inclination, magnification, or distortion of the image using the detected marker (S904), and converts the image data into an assumed two-dimensional data size.
A binalization circuit 708 binalizes the two-dimensional data to determine each bit data of the bits constituting the two-dimensional data as “0” or “1” (S905), and stores the data in the memory 702 in the order of the output reproduced data. Thereafter, by removing the marker from the binalized data (S906), one page of two-dimensional data is acquired (S907).
An error correction circuit 706 converts the two-dimensional data acquired in this manner into a plurality of data sequences, performs error correction processing to each data sequence (S908), and removes a parity data sequence.
A scramble release circuit 705 releases the scramble for adding the pseudo-random number data sequence (S909).
A CRC operation circuit 704 performs error detection processing by CRC (S910) to delete a CRC parity, confirms that the user data in the memory 702 includes no error, and transfers the user data from the memory 702 to the input/output control circuit 90 (S911).
Here, in the above described optical information recording/reproducing device 10 in the present embodiment, distortion correction according to a nonlinear image distortion which is a feature of the present embodiment is detailedly described with reference to
In the present embodiment, a distortion amount is to be calculated by accurately detecting a known pattern although a nonlinear distortion occurs in a reproduction image, and reproduction quality when a normal page is reproduced is to be improved based on the calculated distortion amount.
First, with reference to
Modifications to be described below are not limited to the present embodiment.
The description has been made based on the hologram recording technique by the angle multiplexing recording method in the present embodiment, but the present invention is not limited to the angle multiplexing recording method, and may be applied to other hologram recording techniques such as a shift multiplexing recording method, or signal processing in optical information storage mediums for data other than a hologram.
Furthermore, it has been described that a marker search range is expanded at the time of distortion learning in the present embodiment, but the marker search range may be expanded when a distortion amount is calculated and the distortion amount exceeds a predetermined threshold. In this case, the normal search range is searched for the marker when the distortion amount is small, and it is possible to reduce the processing time.
It has been described that a distortion amount is learned in a page to be reproduced and is directly used in the page in the present embodiment, but the page in which the distortion amount is learned may be different from the page in which the learned distortion amount is used. For example, by using, in the next page to be reproduced, the distortion amount learned after reproduction signal processing is completed, it is possible to more accurately perform distortion learning.
The difference between the present embodiment and the first embodiment is that a learning page is used at the time of distortion learning instead of a normal page, and that a marker is detected by expanding a search range for the marker at the time of distortion learning. As described above, a distortion amount of an image can be estimated using a movement amount of a marker, but it is difficult to correctly detect the marker when a distortion occurs, and the marker can be out of the range if the search range is set in the vicinity of an ideal position when the marker after the distortion largely deviates from the ideal position.
In view of this situation, by learning a distortion amount in a learning page in which a marker alone is recorded, and expanding a search range for the marker at the time of distortion amount learning, the marker at a position largely shifted from an ideal position is to be detected in the present embodiment.
With reference to
When a reproduction image is a distortion learning page, a distortion learning circuit 101 performs distortion learning based on the information on the reproduction image (S902).
The distortion learning method using a learning page is described with reference to
However, when the search range is expanded in a page in which data is displayed in the area other than the marker, the possibility that the wrong area is erroneously detected as the marker is increased as the area is expanded. Thus, by displaying no information in the area other than the marker in the learning page, the possibility of erroneous detection can be reduced. By performing such distortion amount calculation to all the markers, it is possible to accurately detect a marker and correct distortion although any kind of distortion occurs in a reproduction image while the possibility that the marker is erroneously detected is reduced.
As described above, by using the learning page having no data other than the marker, expanding the marker search range, and detecting the marker, it is possible to calculate distortion amount occurring in the reproduction image. Furthermore, by using the calculated distortion amount for searching for the marker when a normal page is reproduced, it is possible to perform correction according to the distortion amount.
It has been described that data is not recorded in the area other than the marker in the learning page in the present embodiment, any kind of pattern may be used unless the pattern causes erroneous detection of a marker. For example, by arranging a data pattern having a high cycle in the area other than the marker, the components other than the marker can be optically cut using a filter for cutting high-frequency components.
The difference between the present embodiment and the first embodiment is that distortion learning is performed according to quality deterioration of a reproduction image and that a search range for a marker is expanded at the time of distortion learning.
With reference to
When the quality of the reproduction image is deteriorated, a distortion learning circuit 101 performs distortion learning based on the information on the reproduction image (S902).
When an image distortion occurs at the time of the distortion learning, the position of a marker in a page can be largely shifted from the ideal position and be out of the normal search range. Thus, when a learning page is reproduced, the marker is detected by expanding the normal search range and searching the expanded search range.
By performing such distortion amount calculation to all markers in all pages, it is possible to accurately detect a marker and correct distortion although any kind of distortion occurs in a reproduction image.
As described above, by expanding the marker search range according to the quality deterioration of the reproduction image, and detecting the marker, it is possible to calculate the distortion amount occurring in the reproduction image. Furthermore, by using the calculated distortion amount for searching for the marker when a normal page is reproduced, it is possible to perform correction according to the distortion amount.
The difference between the present embodiment and the first embodiment is that a marker for learning a distortion amount and a marker for correcting distortion are simultaneously provided in a page, the distortion amount is learned using the marker for learning distortion, and the learned distortion amount is used for searching for the marker for correcting distortion. In the present embodiment, the marker for learning distortion is referred to as a marker A, and the marker for correcting distortion is referred to as a marker B. With reference to
dx=rx(1+K1*r2K2*r4+ . . . )+(P1(r2+2*rx2)+2*P2*rx*ry)(1+P3*r2+P4*r4+ . . . )
dy=ry(1+K1*r2+K2*r4+ . . . )+(P1(r2+2*ry2)+2*P2*rx*ry)(1+P3*r2+P4*r4+ . . . )
By calculating two variables of K and P with the above expressions, the distortion amount can be represented, and the degrees of K and P are determined according to the number of markers A used for the calculation. When the number of calculated K and P becomes larger, the distortion amount can be more accurately represented, but the optimal degrees are determined according to the number of markers A which can be arranged in the page and the processing amount necessary for the calculation.
On the assumption that the optimal K and P are calculated with the above Brown's model, a method for moving a marker B search range when the marker B is searched for is described with reference to
Furthermore, the present invention is not limited to the above described embodiments, and includes various modifications. For example, the above embodiments are described in details to easily understand the present invention, and not limited to the configurations having all the described components. Apart of the configuration of one embodiment may be replaced with a part of the configuration of another embodiment, and a configuration of one embodiment may include a configuration of another embodiment. Furthermore, in a part of the configuration of each embodiment, it is possible to add, delete, or replace another configuration.
Furthermore, a part of or all of the above configurations, functions, processing units, processing means, or/and the like may be implemented by hardware, for example, by designing an integrated circuit. Moreover, the above configurations, functions, or/and the like may be implemented by software by interpreting and executing a program which implements the functions by a processor. Programs implementing the functions and information, such as a table, a file, and the like, can be stored in a recording device, such as a memory, a hard disk, or a solid state drive (SSD), or in a storage medium, such as an IC card, an SD card, or a DVD.
Note that, the control line and the information line which are necessary for the description are illustrated, and all control lines and all information lines which are necessary for an actual product are not necessarily illustrated. Practically, it can be considered that most of all configurations are mutually connected.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2016-051856 | Mar 2016 | JP | national |
