KR100579614B1 - Track Servo Control for Holographic ROM System - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a track servo control apparatus for a holographic ROM system, comprising a holographic recording medium on which a track pattern having a constant data value is recorded along a data pattern, and a reproduction reference light generated from a light source on a recording medium. A first optical system for providing a first optical path incident at a predetermined angle, a data light detector for detecting a reproduction signal light incident on the recording medium and diffracted by a data pattern through a second optical system providing a second optical path; A track light detector which detects the reproduction signal light incident on the recording medium and diffracted by the track pattern through the second optical system, and a control part which performs tracking servo control by adjusting the light detection position according to the light detection value by the track light detector. And a track pattern having a constant data value together with a data pattern in the production of the holographic recording medium. By performing the track servo control using the tracking signal at the time of reproduction after recording the turn, there is an advantage that accurate tracking control can always be performed regardless of the presence or absence of data.

Description

Track servo control device for holographic ROM system {APPARATUS FOR CONTROLLING TRACK SERVO IN A HOLOGRAPHIC ROM SYSTEM}

1 is a configuration diagram of a general holographic ROM system reproducing apparatus;

2 is a block diagram of a holographic ROM system to which a track servo control device according to the prior art is applied;

3 is a configuration diagram of a holographic ROM system to which a track servo control device according to the present invention is applied;

4 is a pattern configuration diagram of an optical disk recording medium used in the track servo control apparatus according to the present invention;

5 is a layout view of an arrangement of an optical disc recording medium and a slot according to the present invention;

The present invention relates to a track servo control apparatus for a holographic ROM system, and more particularly to a tracking servo control for reproducing data stored in a recording material layer of a holographic ROM disk.

Currently, research and development of holographic recording / reproducing apparatuses capable of storing hundreds to hundreds of Gbytes on optical recording media such as optical disks are being actively conducted for large-capacity and high-speed processing of data storage memories.

Referring to a general holographic recording process, a data mask is disposed on a disk, which is a holographic recording medium, and a conical mirror is disposed below the disk. When parallel light is projected onto the data mask, the parallel light passes through a bit pattern in the form of a hole in the data mask and is irradiated to the disk as signal light. Parallel light is projected to the lower part of the disk, and the reference light having a constant angle in the radial direction of the disk is irradiated through the inclined surface of the conical mirror. This signal light and the reference light meet the recording material layer of the disc, and the holographic data in bits according to the pattern of the first data mask is recorded. Instead of the conical mirrors used, conical mirrors with different mirror tilt angles can be used to write new data to the disc using Angular Multiplexing.

A pickup device for reproducing data stored through such a recording process according to the related art is incident through a first optical system that is generated from the light source 10 and provides a first optical path L1 as shown in FIG. 1. A mirror 20 for reflecting the reproduced reference light to be incident on the recording medium 1 at a predetermined angle, and an actuator for adjusting the incidence angle of the recording reference 1 of the reproduction reference light by adjusting the arrangement angle of the mirror 20. And a light detector 30 for detecting the reproduction signal light incident on the recording medium 1 and diffracted in the recording material layer through a second optical system provided with the second optical path L2.

The first optical system scans the reducer 50 for deforming the light emitted from the light source 10 and the light passing through the reducer 50 to the mirror 20 through pores to provide a reproduction reference light. An aperture 60. The second optical system includes an objective lens 71, a slit 73, and a condenser lens 75 for injecting light diffracted from the recording medium 1 into the light detector 30.

In the holographic pickup device configured as described above, when the reproduction reference light is incident on the recording medium 1 at a predetermined angle (reference light incident angle using oxygen) by the mirror 20 whose arrangement angle is adjusted by an actuator (not shown). The reproduction signal light diffracted in the recording material layer of the recording medium 1 is detected by the light detector 30. Then, new data can be reproduced from the recording medium 1 by adjusting the placement angle of the mirror 20 through an actuator (not shown) to adjust the incident angle of the recording medium 1 of the reproduction reference light.

On the other hand, the holographic ROM system, like other optical recording media, requires a track servo control to accurately reproduce data recorded on a desired track when the optical disk rotates at high speed. A track servo control device was proposed in 58675.

2 is a block diagram of a holographic ROM system including a track servo control apparatus disclosed in Patent Application No. 2003-58675.

The holographic ROM system disclosed in the same reference includes the light source 100, the shutter 102, the first and second reflectors 104 and 108, the three-segment light detecting means 130, the optical disc 140, the slit control unit 150, and Actuator 160 is included. Here, the optical system 106 composed of the optical lenses 106b and 106c and the ND (Neutral Density) filter 106a is formed between the first and second reflectors 104 and 108, and the optical disk 140 and the light detector A slit 120 having optical lenses 110a and 110b and three holes 120a, 120b and 120c through which the reproduction signal light is transmitted is formed therebetween. In addition, the three-split light detecting means 130 is composed of three light receiving elements (A, B, C) corresponding to the respective holes (120a, 120b, 120c).

The optical disk 140 is a holographic medium in which data recorded in an angular overlapping manner is stored, and is rotated by a motor 145 driven when data is reproduced. The signal of multiple tracks is included by diffracting the reproduction reference light incident on the optical disk 140 through the first reflector 104 and the second reflector 108 and the interference fringe recorded on the optical disk 140 is incident on the path. Reproduced signal light is generated.

The slit 120 has three holes 120a, 120b, and 120c which are moved to the left and right by the actuator 160 and are capable of transmitting the reproduction signal light. In this case, the reproduction signal light that has passed through the holes 120a, 120b, and 120c is transmitted. When present, the reproduction signal light is detected by the light receiving element A, B or C, and the light receiving element A, B or C converts the reproduction signal light into a reproduction signal and provides it to the slit controller 150.

The three-split light detecting means 130 is composed of three light receiving elements A, B, and C installed in correspondence with the holes 120a, 120b, and 120c of the slit 120, respectively. , C receives the reproduction signal light transmitted through the holes 120a, 120b, and 120c to generate a reproduction signal, and the reproduction signal is provided to the slit controller 150. At this time, the reproduction signal light passing through the hole 120b is detected by the light receiving element B, and the reproduction signal light passing through the hole 120c is detected by the light receiving element C, and the reproduction signal light passing through the hole 120a. Is detected by the light receiving element A.

The slit control unit 150 generates a servo control signal for track servo control when the reproduction signal is input from the light receiving element B or C of the three-segment light detecting means 130 to drive the actuator 160 to drive the slit 120. In order to fix the slit 120, the signal is provided to the actuator 160 to fix the slit 120 when the reproduction signal is generated in the light receiving element A of the three-segment photodetector 130. At this time, the reproduction signal generated by the light-receiving element A of the three-segment light detecting means 130 is signal-processed by an unshown signal processor and output.

As such, the track servo control is performed using the holes 120b and 120c among the holes constituting the slit 120, and the data signal is detected using the position hole 120a at the center.

In detail, when the reproduction signal is input from the light receiving element B or C, the slit controller 150 determines that the track servo is not properly performed and provides the servo control signal to the actuator 160 to move the slit 120. In addition, the actuator 160 performs track servo control by moving the slit 120 left and right according to the servo control signal. In addition, when a reproduction signal is input from the light receiving element A, the slit controller 150 provides a signal for fixing the slit 120 to the actuator 160, and the actuator 160 is provided from the slit controller 150. The slit 120 is fixed based on the signal. At this time, the reproduction signal detected by the light receiving element A is signal-processed by an unshown signal processor and output.

However, as described above, in the holographic track servo control according to the prior art, the track servo control is performed using the reproduction signal light diffracted by the data pattern of the optical disk which is a holographic recording medium, but no data exists in a specific section. If not, tracking control is difficult.

In addition, different amounts of light are detected in the light-receiving elements B and C used for the track servo control among the three-segment light detecting means, and precise tracking control cannot be performed because these are not taken into consideration. There is this.

SUMMARY OF THE INVENTION The present invention has been proposed to solve such a problem of the prior art, in which a track servo control is performed by recording a track pattern having a constant data value together with a data pattern at the time of manufacture of a holographic recording medium and using it as a tracking signal during reproduction. By doing so, the object of the present invention is to always perform accurate tracking control regardless of the presence or absence of data.

A track servo control apparatus for a holographic ROM system according to the present invention for achieving this object comprises a holographic recording medium having a pair of track patterns in which a constant data value is recorded along both sides of the data pattern and from a light source. A first optical system for providing a first optical path for causing the generated reproduction reference light to enter the recording medium at a predetermined angle; and a second optical path for providing a second optical path for reproduction signal light incident on the recording medium and diffracted by the data pattern. A data light detector for detecting through a second optical system, a first and second track light detector for detecting a reproduction signal light incident on the recording medium and diffracted by the pair of track patterns through the second optical system, and the first And a control unit which performs tracking servo control by adjusting the light detection position according to the light detection value by the two-track light detection unit. It should.

Hereinafter, exemplary embodiments will be described in detail with reference to the accompanying drawings. This embodiment allows for a better understanding of the objects, features and advantages of the present invention. However, the present invention is not limited to this embodiment, of course.

FIG. 3 is a block diagram of a holographic ROM system to which a track servo control apparatus according to the present invention is applied, and in comparison with the holographic ROM system shown in FIG. 1, the same components have the same reference numerals.

4 is a pattern configuration diagram of an optical disk recording medium 210 fabricated for the track servo control apparatus according to the present invention, in which a normal data pattern 216 is recorded, and around both sides along the data pattern 216. A pair of track patterns 211 and 213 are arranged by recording constant data values.

The holographic ROM system for reproducing the recording medium 210 of FIG. 4 is a reproduction reference light incident from a light source 10 and incident through a first optical system providing a first optical path L1, as shown in FIG. Mirror 20 to reflect the light incident to the recording medium 210 at a predetermined angle, and an actuator for adjusting the incident angle of the recording medium 210 of the reproduction reference light by adjusting the arrangement angle of the mirror 20 (not shown). And a data light detector 30 for detecting the reproduction signal light incident on the recording medium 210 and diffracted by the data pattern 216 through a second optical system provided with the second optical path L2, and a recording medium ( The first and second track light detectors 230 for detecting the reproduction signal light incident on the 210 and diffracted by the pair of track patterns 211 and 213 through a second optical system provided with the second optical path L2, respectively. 240 and the light detection values of the first and second track light detectors 230 and 240. Adjusting the light detection position, it is configured to include a controller 250 that performs a tracking servo control.

The first optical system scans the reducer 50 for deforming the light emitted from the light source 10 and the light passing through the reducer 50 to the mirror 20 through pores to provide a reproduction reference light. An aperture 60. The second optical system includes an objective lens 71 and a slit 220 for injecting light diffracted from the recording medium 210 into the data light detector 30 and the first and second track light detectors 230 and 240. And a condenser lens 75.

As shown in FIG. 5, the slit 220 is detected by the first and second track light detectors 230 and 240 by passing the reproduction signal light by the pair of track patterns 211 and 213 adjacent to the data pattern 216. It has one wide hole to be.

The pickup and tracking control process by the holographic ROM system according to the present invention configured as described above will be described with reference to FIGS. 3 to 5.

First, the light emitted from the light source 10 is reflected by the mirror 20 whose arrangement angle is adjusted by an actuator (not shown), and is reproduced at a predetermined angle (reference light incident angle using oxygen) on the recording medium 210. Reference light is incident.

The reproduction signal light incident on the recording medium 210 is diffracted by the data pattern 216 of the recording medium 210 and the pair of track patterns 211 and 213 so that the reproduction signal light is transmitted through the second optical path L2. It enters into (71).

As a result, the reproduction signal light generated by the data pattern 216 passes through the lens 71, the slit 220, and the lens 75 sequentially and is detected by the data light detector 30. The pair of track patterns 211 and 213 are detected. Reproduced signal light is sequentially detected by the first and second track light detectors 230 and 240 through the lens 71, the slit 220, and the lens 75, respectively.

The light amount values detected by the first and second track light detectors 230 and 240 are transmitted to the controller 250, and the controller 250 is the light detection value by the first and second track light detectors 230 and 240. Outputs the data detected by the data light detection unit 30 at a position where the light detection values of the first and second track light detection units 230 and 240 become maximum while performing the tracking servo control by adjusting the light detection position according to the above. . Of course, in the state where accurate tracking is completed, the light by the first and second track light detectors 230 and 240 is set after setting the position or the threshold range where the light detection values of the first and second track light detectors 230 and 240 become the maximum. Even when the detection value is included in the threshold range, it may be determined as a normal tracking state.

In the above description, but limited to one embodiment of the present invention, it is obvious that the technology of the present invention can be easily modified by those skilled in the art. Such modified embodiments should be included in the technical spirit described in the claims of the present invention.

As described above, the present invention records the pair of track patterns having a constant data value together with the data patterns in the production of the holographic recording medium, and then performs the track servo control by using the track servo signals during the playback, thereby providing the presence or absence of data. You can always perform accurate tracking control regardless of

Further, by performing track servo control in consideration of the light amount value detected by the pair of track patterns, more precise tracking control can be performed.

Claims (3)

A holographic recording medium having a pair of track patterns in which constant data values are recorded around both sides of the data pattern, A first optical system providing a first optical path for causing the reproduction reference light generated from the light source to enter the recording medium at a predetermined angle; A data light detector for detecting a reproduction signal light incident on the recording medium and diffracted by the data pattern through a second optical system providing a second optical path; First and second track light detectors for detecting reproduction signal light incident on the recording medium and diffracted by the pair of track patterns through the second optical system, respectively; Control unit for performing tracking servo control by adjusting the light detection position according to the light detection value by the first and second track light detectors Track servo control device for a holographic ROM system comprising a. The method of claim 1, And the control unit completes the tracking servo control at a position where the light quantity values detected by the first and second track light detectors are maximized. The method of claim 1, And the controller is configured to complete the tracking servo control at a position where the light quantity values detected by the first and second track light detectors fall within a preset threshold range.

Images