KR20050041732A - Information storage medium and method and apparatus for reproducing data from the same - Google Patents

Abstract

An information storage medium and method and apparatus for reproducing data from the information storage medium are disclosed.

The disclosed information storage medium has a test zone in which a test pattern for measuring an error rate of the information storage medium is formed in a lead-in area and a lead-out area, and a data reproducing method of the information storage medium is provided in the lead-in area and the lead-out area. Form first and second test patterns for measuring an error rate, perform tracking on the first and second test patterns, and measure an error rate for a predetermined radius with respect to the first and second test patterns. Error correction during playback.

As described above, the error rate according to the tilt is measured, and the data is reproduced by correcting the error using the error rate to improve data reproduction performance.

Description

Information storage medium and method and apparatus for reproducing data from the same}

The present invention relates to an information storage medium and a data reproducing method and apparatus for improving data reproducing performance. More particularly, the present invention relates to an area in which a test pattern for testing an error rate according to a tilt of an information storage medium is recorded. The present invention relates to an information storage medium, a data reproducing method, and an apparatus for improving reproducing performance by measuring and correcting errors due to tilt.

In general, an information storage medium, such as an optical disk, is widely used as an information storage medium of an optical pickup apparatus for recording / reproducing information in a non-contact manner, and may be a compact disk (CD) or a digital multifunction disk (DVD) according to the information recording capacity. ; digital versatile disk). Also, as a disc capable of recording, erasing and playing back information, 650MB CD-R, CD-RW, 4.7GB DVD + R / RW (rewritable), DVD-RAM (random access memory), DVD-R / RW (rewritable) And 650MB CD and 4.7GB DVD-ROM. Furthermore, high-density optical discs (HD-DVD) having a recording capacity of 20 GB or more are also being developed.

On the other hand, the demand for information storage media for mobile is increasing day by day. For use in mobile, research and development on the miniaturization of information storage medium is in progress. Although there are many problems to be solved for miniaturization, it is one of the important problems to compensate for the reduction in recording capacity due to miniaturization.

However, as the capacity of the information storage medium increases, the length and width of the pit recorded on the read-only information storage medium decrease. As the length and width of the pit decrease as described above, the signal of the minimum mark becomes very small, which causes a problem of deterioration of data reproduction characteristics.

Therefore, as the data capacity becomes higher, a solution for compensating for deterioration of reproduction characteristics of data is required.

FIG. 1A illustrates a layout for each region of a conventional read-only information storage medium. The information storage medium includes a lead-in area 100 provided on an inner circumference and a data area in which user data is recorded adjacent to the lead-in area 100. FIG. 105.

The lead-in area 100 includes a control data zone 100a in which disk related information and copy protection information are recorded, a buffer zone 100b, and an information zone 100d in which drive or disk state related information is recorded. ). In addition, although a content to be recorded is not currently determined, a reserved zone 100c may be further provided to be left as a free area for data to be added in the future.

As shown in FIG. 1A, a conventional read-only information storage medium is not provided with a separate area for improving data reproduction characteristics.

Fig. 1B shows the area-by-area layout of a conventional recordable information storage medium. The recordable information storage medium includes a lead-in area 110 and a data area 120 in which user data is recorded adjacent to the lead-in area 110.

The lead-in area 110 includes a control data zone 110a in which disk related information and copy protection information are recorded, a buffer zone 110b, an OPC zone 110d for measuring an optimum recording power, and a drive. Or an information zone 100e in which disk state related information is recorded. In addition, although a content to be recorded is not currently determined, a reserved zone 110c may be further provided that is left as a free area for data to be added in the future.

As described above, the recordable information storage medium includes an OPC zone 110d to improve recording characteristics. On the other hand, since the read-only information storage medium does not have an area for data reproduction characteristics, there is a need to find a method for improving data reproduction characteristics as the data capacity becomes larger and denser.

Disclosure of Invention The present invention has been made to solve the above problems, and includes a test area for improving data reproduction performance, and an information storage medium having improved data reproduction characteristics by using data of a predetermined pattern recorded in the test area. It is an object of the present invention to provide a data reproduction method and apparatus.

In order to achieve the above object, the information storage medium according to the present invention is a reproduction-only information storage medium including a data area, a lead-in area and a lead-out area in which user data is recorded,

A test zone having a test pattern for measuring an error rate of the information storage medium is provided in the lead-in area and the lead-out area, respectively.

The test pattern is preferably a pattern for measuring an error rate according to tilt.

The test pattern is preferably recorded after a predetermined modulation scheme is applied.

The test pattern may be tracking by a phase difference detection method (DPD) or a push-pull method.

In order to achieve the above object, the data reproducing method according to the present invention is a method for reproducing data in a reproduction-only information storage medium including a data area, a lead-in area and a lead-out area in which user data is recorded.

Forming first and second test patterns for measuring an error rate in the lead-in area and the lead-out area; Performing tracking on the first and second test patterns; Measuring an error rate for a predetermined radius for the first and second test patterns; And correcting an error in reproducing data by using the measured error rate.

The error correcting step may include: calculating a compensation tilt amount for the error rate due to the tilt using the measured error rate; And reproducing data by compensating a value corresponding to the compensation tilt amount.

The compensation tilt amount may be obtained by a tilt value indicating a minimum error rate for a predetermined radius among the error rates measured by the first and second test patterns.

In order to achieve the above object, a data reproducing apparatus according to the present invention is a device for reproducing data recorded on an information storage medium including a data area, a lead-in area and a lead-out area in which user data is recorded,

A pickup unit having a light source for irradiating light to the information storage medium and a detector for detecting light reflected from the information storage medium; A reproducing signal having a tilt compensation circuit for detecting an error rate corresponding to a tilt from a test pattern formed in the lead-in area and the lead-out area by the detector and correcting an error of data by using a tilt compensation amount corresponding to the error rate It is characterized in that it comprises a processing unit.

Hereinafter, an information storage medium, a data reproducing method and an apparatus according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 2, the information storage medium according to the present invention includes a data area 20 in which user data is recorded, a lead-in area 10 provided on an inner circumference of the user data area, in which disk-related information and the like are recorded, and the user. And a lead-out area 30 provided on the outer circumferential side of the data area.

In the lead-in area 10, a control data zone 10a in which disk related information and copy protection information are recorded, a buffer zone 10b, a reserved zone 10c, and an information zone 10e in which drive or disk status related information is recorded. ) May be provided. Disc-related information includes, for example, information on types of storage media such as recordable discs, write once discs, and playback-only discs, information on the number of recording layers, recording speed information, and disc size information. have.

A test zone for measuring an error rate according to the tilt of the information storage medium is provided in at least one of the lead-in area 10 and the lead-out area 30.

The test zone may be provided in the lead-in area 10 or the lead-out area 30, or may be provided in both the lead-in area 10 and the lead-out area 30. 2 illustrates an example in which test zones 10d and 30a are provided in both the lead-in area 10 and the lead-out area 30.

Data of a predetermined pattern for measuring an error rate is recorded in the test zones 10d and 30a. The pattern for error rate measurement may be, for example, a 00h pattern.

In addition, in order to increase the reliability of the test, the test pattern may be repeatedly formed in the lead-in area and the lead-out area, respectively. That is, it is preferable to repeatedly record the test pattern in case the test pattern recorded in the lead-in area and the lead-out area is damaged and the test cannot be performed.

Pits or grooves of a predetermined pattern for measuring an error rate may be formed in the test zones 10d and 30a. The test pattern for measuring the error rate is recorded by, for example, an RLL (d, k) modulation scheme and recorded in a predetermined pattern.

The modulation scheme of RLL (d, k) is a modulation scheme having a minimum number of (d) and a maximum number of (k) zero bits between 1 bit and 1 bit. For example, in the RLL (1,7) modulation scheme, data is written in pits and spaces having a length in the range of 2T-8T, where T represents the minimum mark length.

When tracking the test pattern, a differential phase detect (DPD) method or a push-pull method is employed.

In the above example, the test pattern is formed in both the lead-in area and the lead-out area. However, two test patterns may be formed in the lead-in area or two test patterns may be formed in the lead-out area. In other words, two test zones may be provided in the lead-in area, and a test pattern for measuring an error rate due to tilt may be formed in each of the two test zones.

By providing the test zones 10d and 30a in the lead-in area 10 and the lead-out area 30 as described above, the OPC area 110d is provided in the recordable information storage medium shown in FIG. 1B. It is advantageous in that it can secure consistency.

Next, a method of reproducing data in the information storage medium according to the present invention will be described.

The error rate was measured for each of the recording capacities of 31 GB, 33 GB, and 35 GB to determine the tilt margin characteristics according to the recording capacity. 3A is a graph showing a result of measuring an error rate according to a tilt angle when the recording capacity is 31GB, FIG. 3B is when the recording capacity is 33GB, and FIG. 3C is when the recording capacity is 35GB.

Error rates for tangential tilt and radial tilt were measured for each recording capacity. Here, the error rate represents, for example, the byte error rate, the tangential tilt represents the tangential direction tilt of the information storage medium, and the radial tilt represents the radial tilt of the information storage medium. The RLL (1,7) modulation method was adopted as the recording modulation method, and the track pitch was measured while changing to 0.32 µm and the minimum recording mark to 0.119 µm, 0.112 µm and 0.105 µm.

The following is a table of tilt margins by error rate for tangential tilt and error rate for radial tilt.

 Tilt capacity    31 GB     33 GB    35 GB   Tangential   -0.7 to 0.6  -0.55 to 0.5  -0.45 to 0.4   Radial  -0.7 to 0.6  -0.65 to 0.45  -0.5 to 0.4

 Here, the tilt margin may be expressed as a tilt angle range satisfying the standard error rate shown in each graph. Referring to Table 1 and FIGS. 3A to 3C, it can be seen that the tilt margin decreases as the recording capacity increases. Accordingly, it is understood that the tilt margin is further reduced as the recording capacity is increased and the density is increased, thereby making it difficult to secure good data reproduction performance.

This means that the recording capacity is more affected by the tilt as it becomes higher and higher in density. Therefore, as the recording capacity becomes higher and higher, it is further required to correct an error due to tilt.

FIG. 4A shows the results of measuring the error rate in the first test pattern formed in the lead-in area 10 of the information storage medium 53 and the second test pattern formed in the lead-out area 30 according to the present invention. The graph is shown. Here, although the error rate for the radial tilt was measured, the following method can be equally applied to the error rate for the tangential tilt.

Tracking is performed to measure the error rate in the test pattern. At this time, tracking may be implemented by a differential phase detection (DPD) method or a push-pull method. The phase difference detection method is a method of implementing a tracking servo by the phase difference of an optical spot formed in a four-segment photodetector, and the push-pull method is a method of implementing servo by the left and right signal difference of an optical spot formed in the photodetector. Since it is known, a detailed description thereof will be omitted here.

Next, the error rate is measured at a point where the radius r is r1 using the first test pattern formed in the test zone 10d of the lead-in area 10, and the test zone of the lead-out area 20 is measured. The error rate at the point where the radius r is r2 is measured using the second test pattern formed in 30a).

As a result of measuring the error rate according to the tilt angle at the point where r = r1, the first tilt angle (a °) having the minimum error rate was obtained, and the error rate according to the tilt angle at the point where r = 2 was measured. The minimum second tilt angle b ° is obtained.

A linear equation of the tilt angle according to the radius can be obtained using the first and second tilt angles a and b representing the minimum error rate with respect to the predetermined radius r1 and r2. This is because the tilt of the information storage medium changes linearly with radius.

FIG. 4B shows a straight line graph obtained using the values (r1, a) (r2, b) obtained in FIG. 4A. Using the measured values (r1, a) (r2, b), the general equation for the tilt angle representing the minimum error rate according to the radius is obtained as follows.

By using the above equation, the tilt angle can be known at any position of the information storage medium, and the error rate according to the tilt angle can be known. The data reproduction performance can be improved by compensating for the error rate during data reproduction. In other words, the error rate is calculated according to the tilt angle, the compensation tilt amount for each radius that can minimize the error rate is calculated, and the error for tilt is corrected by applying the compensation tilt amount corresponding to the predetermined radius during data reproduction. Can be.

On the other hand, the test pattern for measuring the error rate according to the tilt is preferably configured so that the DC thumb of the signal characteristic graph is 0, for this purpose, it is preferable that the modulation pattern is applied to the test pattern and then recorded on the information storage medium.

For example, in the RLL (d, k) modulation scheme, data is recorded in pits and spaces having a length in the range of (d + 1) T− (k + 1) T. In the RLL (d, k) modulation scheme, d is called a minimum run length and k is called a maximum run length. In order to eliminate the DC component in generating such a data signal, two specific constraints are selected that are within the range of the minimum run length d and the maximum run length k of the modulated code.

That is, the specific constraint field i, j that satisfies d≤i, j≤k is selected. In generating a modulated signal as shown in FIG. 5, the random bit value generator 31 generates a random bit value, and the data pattern generator 32 uses the first pattern to generate a random bit value. And a second test pattern. Then, the first and second test patterns are NRZI encoded 33 to form a bit stream.

The first test pattern and the second test pattern are each composed of a repeating pattern of (i + 1) T and a repeating pattern of (j + 1) T for i, j within a range of d ≦ i, j ≦ k. desirable. The DC component can be removed by making the total length of the first and second test patterns 2n times the minimum common multiple of (i + 1) and (j + 1), where n is a natural number. By making the DC thumb O in this way, a more accurate test signal can be obtained.

6 schematically shows an apparatus for reproducing an information storage medium according to the present invention. The reproducing apparatus of the information storage medium 53 includes a pickup section 40, a playback signal processing section 60, and a control section 70.

More specifically, the pickup 40 is a laser diode 41 for irradiating light, a collimating lens 42 for parallelizing the light irradiated from the laser diode 41, the conversion path of the incident light The beam splitter 44, the objective lens 46 for focusing the light passing through the beam splitter 44 on the information storage medium 53, and the photodetector 54 for detecting light reflected from the information storage medium 53. It includes.

Light reflected from the information storage medium 53 is reflected by the beam splitter 44 and received by a photodetector, for example, a quadrant photodetector 54. The light received by the photodetector 54 is converted into an electrical signal through the calculation circuit unit 50, and the channel 1 Ch1 detected as an RF signal, that is, a thumb signal, and the differential signal channel Ch2 detected by the push-pull method. Is printed via).

In the present invention, the error rate is measured using the thumb signal reproduced by the thumb signal channel. In addition, a tracking servo may be implemented by a push-pull method using a signal reproduced by a differential signal channel, or a tracking servo may be implemented by a differential phase difference method using a signal reproduced by a thumb signal channel.

The error rate measured by the thumb signal channel is output through the thumb signal monitor 55, and the tilt compensation circuit 57 compensates for the tilt according to the amount of compensation tilt corresponding to the measured error rate. The RF signal detected through the thumb signal channel is output through the laser pulse 56. On the other hand, the signal reproduced by the differential signal channel Ch2 is input to the control unit 70, the tracking servo is implemented by the control unit 70.

The information storage medium according to the present invention may be applied to a read-only information storage medium, and may be applied to a storage medium having one or more information storage layers.

As described above, according to the read-only information storage medium, the data reproducing method and the apparatus according to the present invention, by separately providing a test zone for measuring the error rate according to the tilt in at least one of the lead-in area and the lead-out area, The reproduction performance of data can be improved.

Furthermore, error rate measurement and error correction due to tilt play a very important role in improving playback performance as the error rate due to tilt is increased due to the decrease in the pit length due to the increase in recording capacity and the securing of high capacity in a small storage medium. Therefore, by measuring the error rate according to the tilt, and calculating the amount of compensation tilt according to the radius of the information storage medium obtained using the error rate to correct the error, it is possible to ensure more reliable data reproduction performance.

In addition, according to the data reproducing method of the present invention, a test pattern for measuring an error rate according to tilt in a test zone can be formed, and a reliable error rate can be measured using a signal characteristic graph for the pattern, and the test pattern is DC. The component can be removed to allow more accurate error rate measurements.

FIG. 1A is a diagram illustrating a region-specific layout of a conventional read-only information storage medium.

FIG. 1B is a diagram showing the area-specific layout of a conventional recordable information storage medium.

2 is a view showing a layout for each area of an information storage medium according to the present invention.

3A is a graph illustrating an error rate according to a tilt angle when a data capacity is 31 GB.

3B is a graph showing an error rate according to the tilt angle when the data capacity is 33GB.

3C is a graph illustrating an error rate according to a tilt angle when the data capacity is 35 GB.

Figure 4a is a graph showing the results of measuring the error rate according to the tilt angle for the radius r1, r2 of the information storage medium according to the present invention, and the tilt angle at which the error rate is the minimum.

4B is a graph illustrating a tilt angle at which an error rate is minimized with respect to a radius r of the information storage medium using the results obtained through FIG. 4A.

5 is a block diagram showing an apparatus for zeroing a DC thumb of a signal for a pattern for error rate measurement due to tilt.

6 schematically shows an apparatus for reproducing data recorded on an information storage medium according to the present invention.

<Explanation of symbols for main parts of the drawings>

10 ... Lead-in area, 10a ... Control data zone

10b ... buffer, 10d, 30a ... test zone

10 e ... information zone, 20 ... data area

30 ... Leadout area,

Claims (14)

In a reproduction-only information storage medium including a data area, a lead-in area and a lead-out area in which user data is recorded, And a test zone having a test pattern for measuring an error rate of the information storage medium in the lead-in area and the lead-out area, respectively. The method of claim 1, The test pattern is an information storage medium, characterized in that the pattern for measuring the error rate according to the tilt. The method according to claim 1 or 2, The test pattern is recorded after the predetermined modulation method is applied. The method of claim 3, wherein And the data recording modulation method is an RLL (d, k) modulation method. The method according to claim 1 or 2, The test pattern is an information storage medium, characterized in that tracking is performed by a phase difference detection method (DPD) or a push-pull method. The method according to claim 1 or 2, The test pattern is an information storage medium, characterized in that configured so that the DC thumb of the signal characteristic graph is O. A method of reproducing data in a reproduction-only information storage medium including a data area in which user data is recorded, a lead-in area and a lead-out area, Forming first and second test patterns for measuring an error rate in the lead-in area and the lead-out area; Performing tracking on the first and second test patterns; Measuring an error rate for a predetermined radius for the first and second test patterns; Correcting an error in reproducing data using the measured error rate. The method of claim 7, wherein And the first and second test patterns are patterns for measuring an error rate due to tilt of the information storage medium. The method of claim 8, wherein the error correction step, Obtaining a compensation tilt amount for the error rate due to the tilt using the measured error rate; And reproducing data by compensating a value corresponding to the compensation tilt amount. The method of claim 9, wherein the amount of compensation tilt, And a tilt value representing a minimum error rate for a predetermined radius of the error rates measured by the first and second test patterns. The method of claim 9, wherein the amount of compensation tilt, A tilt angle indicating a minimum error rate at a radius r1 of an information storage medium is a, and a tilt angle representing a minimum error rate at a radius r2 is b, and is obtained by using the following conditional expression for an arbitrary radius r. How to. <Conditional expression> The method according to claim 7 or 8, The test pattern is characterized in that the tracking is performed by a phase difference detection (DPD) or push-pull method. The method according to claim 7 or 8, The test pattern is configured such that the DC thumb of the signal characteristic graph is O. An apparatus for reproducing data recorded on an information storage medium including a data area in which user data is recorded, a lead-in area and a lead-out area, A pickup unit having a light source for irradiating light to the information storage medium and a detector for detecting light reflected from the information storage medium; A reproducing signal having a tilt compensation circuit for detecting an error rate corresponding to a tilt from a test pattern formed in the lead-in area and the lead-out area by the detector and correcting an error of data by using a tilt compensation amount corresponding to the error rate And a processing unit.