JP2006185550A - Optical disk recording method and optical disk recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical disk recording method and an optical disk recorder capable of suppressing such an adverse effect that an exact recording and reproducing operation is affected by a deterioration phenomenon, while reducing the deterioration of a recording thin film of the optical disk even for a DVD-RW. <P>SOLUTION: In the case that a linking recording operation of data is successively applied to a groove track by synchronizing with a wobble of the groove track formed on the optical disk 1 and a land prepit formed at the outer peripheral side of the groove track, a polarity inversion means 6 for changing over a mark and a space of the recording data at random for every linking recording operation, and a recording timing alternation means for changing start and end points of the recording operation within a range of (N/2)T±7T at random for every linking recording operation by taking a channel bit period of the recording data as T and a maximum limited run length of a synchronizing series as N, are equipped in this recorder. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical disc recording method for recording / reproducing digital signals in units of blocks and an optical disc recording apparatus for implementing the method.

  In recent years, DVD-RW using a rewritable phase-change optical disk has become widespread as a recording medium for multimedia. One of the advantages of the phase change optical disk is that the information signal can be directly overwritten by a single laser beam. In other words, when a recorded information track is irradiated with a laser output that is modulated between a recording level and an erasing level according to the information signal, a new signal can be overwritten while erasing the existing information signal.

  In such a rewritable optical disc, the recording thin film deteriorates due to the thermal load due to repeated recording, and the deterioration phenomenon tends to spread as the number of repeated recordings increases. For example, as a mark row having the same pattern is repeatedly recorded at the same position, a deterioration phenomenon occurs in each mark in the mark area. In this deterioration phenomenon, as recording is repeated, a defect is generated in the recording thin film when the same pattern is recorded, and the defect spreads in front and behind the mark portion.

  When data recorded on a DVD-RW optical disc is rewritten, the data is rewritten in units of blocks. Therefore, even when information is changed in a part of the block, the entire block is rewritten. In particular, in a TOC (Table of Contents) area or a directory area in which information relating to the table of contents of recorded information in the disc is recorded, similar data is often repeatedly recorded, and rewriting frequency is high. As a result, the film thickness of the recording thin film fluctuates in the boundary region between the part that is repeatedly melted and solidified and the part that is not melted at all, the thermal and optical characteristics deteriorate, and the quality of the reproduced signal in this part deteriorates. Prevents the accurate recording of information.

  Therefore, an optical disc apparatus has been proposed that can reduce deterioration of the recording thin film of the optical disc at each mark due to repeated recording (see, for example, Patent Document 1 below).

This optical disk apparatus includes a first gap area that is a no-signal section, a first guard data recording area for recording guard data, a synchronization signal, and user data in a sector obtained by dividing a track into a plurality of areas as an optical disk. A data recording area, a second guard data area for recording guard data, and a second gap area that is a no-signal section are continuously formed, and the total length of the first and second gap areas is made constant, The total length of the first and second guard data recording areas is made constant, and when recording, the lengths of the first and second guard data recording areas and the first and second guard data recording areas are recorded. Each time, the amount of change in the first and second gap regions is made smaller than the amount of change in the first and second guard data recording regions, and the polarity of the guard data and The polarity of the signal to be recorded in over data recording area has a configuration are randomly varied.
JP 2000-149277 A (FIGS. 10 and 11, paragraphs 0083 to 0088)

  However, since the above-described conventional optical disc apparatus is configured to provide a guard data storage area for recording predetermined guard data between the header area including the sector identification code and the data area including the synchronization signal, It was not possible to apply to a DVD-RW in which one ECC block as a minimum unit is composed of 16 sectors and one sector is composed of 26 frame areas.

  The present invention can also reduce the deterioration of the recording thin film of the optical disc at each mark due to repeated recording, and suppress the adverse effect of the deterioration phenomenon on the accurate recording / reproduction of information even in DVD-RW. An object of the present invention is to provide an optical disc recording method and an optical disc recording apparatus that implements the method.

  In order to achieve the above object, the invention according to claim 1 is synchronized with a wobble of a groove track formed so as to wobble on an optical disk at a constant period and a land pre-pit formed on the outer peripheral side of the groove track. In continuous recording of data on the groove track, in the optical disk recording method for linking recording so that the recording end point of the recorded data becomes the recording start point of the data to be recorded next, for each linking recording, The step of switching the mark and space of the recording data at random, the channel bit period of the recording data as T, the maximum limit run length of the synchronization code sequence as N, and the start / end points of recording at each linking recording (N / And 2) a step of changing randomly within a range of T ± 7T.

  In the invention according to claim 2, data is continuously transmitted to the groove track in synchronization with the wobble of the groove track formed so as to wobble on the optical disk at a constant cycle and the land prepit formed on the outer peripheral side of the groove track. In the optical disk recording apparatus that performs linking recording so that the recording end point of the recorded data becomes the recording start point of the next data to be recorded, the mark and space of the recording data are randomly assigned for each linking recording. Polarity inversion means for switching to, and the channel bit period of the recording data is T, the maximum limit run length of the synchronization code sequence is N, and the recording start / end point is (N / 2) T ± 7T for each linking recording And a recording timing changing unit that randomly changes within the range.

  Since the present invention is configured as described above, even in a DVD-RW, the deterioration of the recording thin film of the optical disk at each mark due to repeated recording is reduced, and the deterioration phenomenon enables accurate recording and reproduction of information. It is possible to suppress adverse effects.

  FIG. 1 is a block diagram showing the configuration of an embodiment of an optical disk recording apparatus for implementing an optical disk recording method according to the present invention. In FIG. 1, an optical disk 1 has a recording surface and is driven to rotate by a disk motor (not shown). On the recording surface of the optical disc 1, a groove track as an information track is formed in a spiral shape. This groove track is divided in the circumferential direction to form data blocks. An optical head 2 is disposed opposite to the recording surface of the optical disc 1. The optical head 2 incorporates a semiconductor laser (not shown), an optical system, a photodetector, and the like, and irradiates the recording surface of the optical disc 1 with a light spot to record and reproduce data on the groove track. The servo circuit 3 controls rotation of the disk motor, movement control for moving the optical head 2 in the radial direction, focus control for focusing the light spot on the recording surface of the optical disk 1, and tracking for tracking the light spot at the center of the groove track. Control is performed.

  On the other hand, in order to record recording data (hereinafter also referred to as a recording signal) 4 supplied from the outside of the optical disk recording apparatus on a groove track of the optical disk 1, an encoding circuit 5 is provided in a path for driving a semiconductor laser of the optical head 2. A polarity inversion circuit 6, a write strategy generation circuit 7, a recording control circuit 8, a write gate shift circuit 9, and a laser drive circuit 10 are provided, and an address detection circuit 11 is provided in a path for reproducing a signal by the photodetector of the optical head 2. Furthermore, a system control circuit 12 for controlling the operation of the entire optical disc recording apparatus is provided.

  Among these, the encoding circuit 5 performs error correction encoding and 8/16 modulation (DVD format modulation method) on the recording data 4, and the polarity inversion circuit 6 outputs the recording data output from the encoding circuit 5. The polarity is changed randomly at each linking record. The write strategy generation circuit 7 modulates the recording data output from the polarity inversion circuit 6 into a form suitable for recording and supplies it to the laser driving circuit 10, and the write gate shift circuit 9 starts recording on the optical disc 1. A gate signal (hereinafter referred to as a write gate) for randomly changing the timing to be supplied is supplied to the encoding circuit 5 and to the laser driving circuit 10. The encoding circuit 5 starts encoding recording data in accordance with the write gate signal output from the write gate shift circuit 9. The write gate signal supplied to the encoding circuit 5 is output earlier than the write gate signal supplied to the laser drive circuit 10 by the delay time of the laser drive circuit 10. The laser driving circuit 10 controls the optical output of the semiconductor laser of the optical head 2 by outputting the recording data modulated by the write strategy generating circuit 7 in accordance with the write gate of the write gate shift circuit 9. The address detection circuit 11 detects a wobble signal and an address signal from the signal reproduced by the photodetector of the optical head 2 and supplies the wobble signal and the address signal to the servo circuit 3 and the recording control circuit 8. The recording control circuit 8 A recording timing signal is applied to the write gate shift circuit 9 based on the signal.

  The operation of the present embodiment configured as described above will be described below. First, as shown in FIG. 2, the optical disk 1 has a format structure in which a groove track 21 for recording information is formed in a spiral shape on the optical disk 1, and the groove track 21 meanders in a sinusoidal shape with respect to the center. Yes. That is, wobbling is performed at a constant cycle. In synchronization with the wobble, land prepits 22 for recording address information are formed on the outer lands of the groove track 21. The recording data is continuously recorded on the groove track 21 in synchronization with the wobble and land pre-pit 22 of the groove track 21. According to the DVD-RW regulations, synchronization is performed so that the land pre-pits 22 are located in the mark of 14 channel bits of the synchronization code sequence SYNC (hereinafter also referred to as SYNC code) of recording data or in the space of 14 channel bits. Must be recorded.

  When performing such recording, the recording data 4 supplied from the outside of the optical disk recording apparatus is supplied to the encoding circuit 5. The encoding circuit 5 adds to the recording data 4 redundant data such as an error correction code (parity code) for detecting or correcting a data error at the time of reading and outputs the data. The recording data to which the redundant data is added is switched between a mark and a space by the polarity inversion circuit 6 at every linking recording. The recording data output from the polarity inversion circuit 6 is modulated by the write strategy generation circuit 7 into a form suitable for recording, and then supplied to the laser driving circuit 10. The laser driving circuit 10 controls the light output of the semiconductor laser of the optical head 2 by outputting the modulated recording data at the timing according to the write gate of the write gate shift circuit 9. As a result, recording on the groove track 21 is performed.

  At the time of recording, a position detection signal of the groove track 21 and a prepit signal obtained by detecting the land prepit 22 are output from the photodetector of the optical head 2. The servo circuit 3 performs rotation control of a disk motor that rotationally drives the optical disk 1, focus control for focusing the light spot on the recording surface of the optical disk 1, and movement control for moving the optical head 2 in the radial direction, and the optical head 2. Tracking control for tracking the light spot at the center of the groove track 21 is performed on the basis of the position detection signal output from. The address detection circuit 11 detects the address of the data block based on the pre-pit signal, and gives the address detection signal and a position detection signal accompanied by wobbling to the recording control circuit 8. The recording control circuit 8 outputs a timing signal at which the recording data 4 is continuously recorded in the data block of the groove track 21 and applies it to the write gate shift circuit 9. Based on a random time signal output from the system control circuit 12, the write gate shift circuit 9 randomly changes the start / end points of recording within the range of the maximum limit run length of the synchronization code sequence for each linking recording. Let

  Here, when the channel bit period of the recording data is T and the maximum limit run length of the synchronization code sequence is N (= 14), the write gate shift circuit 9 sets the start / end points of recording each time linking recording is performed. (N / 2) A write gate that is randomly changed within a range of T ± 7T is output.

  FIG. 3 is a flowchart showing an example of the processing procedure of the system control circuit 12 in the vicinity of linking recording. That is, in step 101, the address of the last recorded data block is searched from the address information of the address detection circuit 11, and in step 102, the recording timing signal output from the recording control circuit 8 is synchronized with the wobble and land prepit. Next, in step 103, the polarity of the recording data to be additionally recorded is determined, and the output timing of the write gate is determined. Next, a polarity command is given to the polarity inversion circuit 6 in step 104, and subsequently, a write gate is generated from the write gate shift circuit 9 in step 105. In step 106, recording in the data block to be additionally recorded is started.

  With this processing procedure, each time linking recording is performed, the mark and space of the recording data can be switched randomly, and the start and end points of recording can be changed randomly within the range of the maximum limit run length of the synchronous code sequence.

Here, a specific example of the maximum number of bits for randomly changing the recording start timing so as to satisfy the definition of DVD-RW will be described, particularly regarding a phase change optical disc.
When the frequency of the channel bits is 52.32 MHz, the period T of one bit of the channel bits corresponds to 19.1 nsec. The recording start timing changes in the range of 0 to ± 7 bits with a resolution of 1 bit unit. Since this random time shift randomly changes the start / end points of recording, recording degradation caused by the same recording pattern can be reduced.

  FIG. 4 shows the relationship between the polarity of the recording signal and the actual recording state on the optical disc. Here, (a) is a recording signal. When the polarity is not inverted, it is recorded on the recording medium in the state shown in (b), and when the polarity is inverted, the state shown in (c). Is recorded on the recording medium. That is, by reversing the polarity, the non-melted portion and the melted portion of the thin film forming the mask are completely reversed, which gives a further effect in preventing recording deterioration.

Here, the deterioration of the recording medium is reduced as the random shift amount is increased. However, in the DVD-RW specification, as shown in FIG. 5, the positional relationship between the 14T of the synchronization code sequence SYNC and the land pre-pit is specified. Therefore, there is a limit to the amount of shift. That is, the recording code of the SYNC code shown in (a) is modulated, and the recording state of the 14T SYNC code is a 14T mark as shown in (b) or a 14T space as shown in (c). It is formed. The recording signal is recorded in synchronization with the land pre-pit shown in (d) and the wobble signal shown in (e). At this time, the mutual positions of the SYNC code 14T and the land pre-pit need to match, and the land pre-pit needs to enter the SYNC code 14T.

  Therefore, recording is usually performed by changing the recording start position up to ± 7 T by random shift from the state where the land pre-pit is recorded at the center of 14T of the SYNC code. 6A shows the recording timing state when the random shift amount is −7T, and FIG. 6B shows the recording timing state when the random shift amount is + 7T.

  FIG. 7 shows the results of experiments performed on the conventional apparatus and the optical disk recording apparatus to which the present invention is applied in order to confirm the effect when the polarity inversion of the recording data and the random shift of the recording timing are performed according to the present embodiment. It is. Here, the jitter value after repeatedly recording the same recording data on the data block of the optical disc is shown in association with the number of recordings. In this case, after repeatedly recording 1000 times, a jitter value of 15% or less is regarded as a reference for data reproduction based on the condition that the error occurrence probability during demodulation is less than 1 / 10,000.

  As described above, according to the present embodiment, the random shift amount is in the range of (N / 2) T ± 7T, and the polarity of the recording data is reversed at random every time linking recording is performed, so that the limited random shift is performed. It is possible to satisfy the DVD-RW regulations depending on the amount, and to suppress the adverse effect of the deterioration phenomenon at each mark on the accurate recording / reproduction of information.

It is a block diagram which shows the structure of one Embodiment of the optical disk recording device which implements the recording method of the optical disk which concerns on this invention. It is the figure which showed the format structure of the optical disk which is the recording object of recording data in one embodiment of this invention. 6 is a flowchart showing an example of a processing procedure of a system control circuit in the vicinity of linking recording in order to explain the operation of the embodiment of the present invention. FIG. 4 is a diagram showing the polarity of recording data and the actual recording state on an optical disc in order to explain the operation of an embodiment of the present invention. FIG. 4 is a diagram showing a recording state synchronized with a land pre-pit in order to explain the operation of an embodiment of the present invention. FIG. 5 is a diagram showing a state of random shift recording in order to explain the operation of the embodiment of the present invention. It is a diagram which shows the experimental result each performed with respect to the conventional apparatus and this invention in order to confirm the effect of one embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical disk 2 Optical head 3 Servo circuit 4 Recording data 5 Encoding circuit 6 Polarity inversion circuit (polarity inversion means)
7 Write Strategy Generation Circuit 8 Recording Control Circuit 9 Write Gate Shift Circuit 10 Laser Drive Circuit 11 Address Detection Circuit 12 System Control Circuit 21 Groove Track 22 Land Prepit

Claims (2)

Recorded when data is continuously recorded on the groove track in synchronization with the wobble of the groove track formed so as to wobble on the optical disc at a constant cycle and the land prepit formed on the outer periphery of the groove track. In the recording method of the optical disk for linking recording so that the recording end point of the data becomes the recording start point of the data to be recorded next,
A step of randomly switching the mark and space of the recording data for each linking recording;
Assuming that the channel bit period of the recording data is T and the maximum limit run length of the synchronization code sequence is N, the recording start / end points are randomly set within the range of (N / 2) T ± 7T for each linking recording. Step to change,
An optical disc recording method comprising: Recorded when data is continuously recorded on the groove track in synchronization with the wobble of the groove track formed so as to wobble on the optical disc at a constant cycle and the land prepit formed on the outer periphery of the groove track. In the optical disc recording apparatus that performs linking recording so that the recording end point of the data becomes the recording start point of the data to be recorded next,
Polarity reversing means for randomly switching the mark and space of the recording data for each linking recording,
Assuming that the channel bit period of the recording data is T and the maximum limit run length of the synchronization code sequence is N, the recording start / end points are randomly set within the range of (N / 2) T ± 7T for each linking recording. Recording timing changing means to be changed,
An optical disc recording apparatus comprising:

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