JP2959006B2 - Data recording / playback method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data recording / reproducing method for an optical disk for recording / reproducing data in sector units.

2. Description of the Related Art An optical disc is provided with guide tracks that can be optically detected, such as guide grooves, concentrically or spirally, for reasons such as higher density of recording tracks, discrete partial writing, and erasing. A recording layer formed on the track is irradiated with a laser beam having a diameter of 1 μm or less, and recording is performed by drilling or causing changes in reflectance and transmittance. When recording digital information having a variable data length, a track is divided into a plurality of sectors to increase recording efficiency, and information is recorded and reproduced in units of about 512 bytes or 1 Kbyte. Each sector is composed of a sector ID section including track address information and sector address information, and a data field section for recording and reproducing data. In an optical disc, a synchronization pull-in signal part for locking in a PLL (Phase Locked Loop), a data head identification mark which is added before the recording data and is a synchronization signal for identifying the head of data. It is composed of a DM (hereinafter referred to as a data mark) and a data part, and at the time of data demodulation, word synchronization for demodulation is achieved by detecting the data mark from the reproduced signal.

On the other hand, when various defects, dusts, scratches, etc. are present on the base material, recording film, protective layer, etc. of the optical disc, a dropout occurs in the reproduced signal. However, the recording pit and track pitch of the optical disc are about 1 μm. The raw error rate is very poor, and there are many long burst-like dropouts. This burst-like dropout often affects the PLL operation during playback,
When the oscillation frequency of the LL changes, a bit slip phenomenon occurs in which the number of self-reproduced clocks increases and decreases, and all the sector data after the word synchronization is shifted during data demodulation may become erroneous.

In order to solve such a problem, means for inserting a resynchronization signal at regular intervals in sector data when recording data on an optical disc is usually employed. An example of this format is shown in FIG. Sector data is provided at a regular interval, a synchronization pull-in signal (SYNC) 1 for PLL synchronization pull-in, a data mark (DM) 2 for identifying the head of data, and a re-synchronization for data demodulation. , And a data section 4 divided into m blocks (hereinafter referred to as frames). Data recording / reproduction is executed by detecting a sector identifier (ID) 5 at the head of a sector and reading the address of a target sector.

With such a configuration, even if the word synchronization of demodulation is deviated due to the bit slip phenomenon caused by a long dropout or the like as described above, the error is suppressed on a frame basis by the re-synchronization signal, and from the next frame, ,
Normal demodulation can be performed. In such a data format, when reproducing data of a target sector, a demodulation circuit is activated by detecting a data mark from a reproduced signal, and data demodulation of the target sector is executed.
If a data mark cannot be detected due to a disk defect or the like, demodulation is started by detecting a resynchronization signal RS existing in the next frame. Also, when attempting to reproduce an unrecorded sector in which no data is recorded in the data field, the demodulation circuit is not activated because no data mark is detected, and by checking an envelope signal or the like indicating whether or not there is a reproduced signal, , It is determined that the sector is an unrecorded sector.

On the other hand, the spot light of the laser beam focused on the optical disk surface is about 1 μm, and the track pitch of the optical disk is usually about 1.6 μm, but the intensity of the laser beam has a Gaussian distribution and is outside the range of 1 μm. Even the portion returns to the signal reproducing circuit as some reflected light.
This affects reproduction signal processing as a so-called crosstalk phenomenon in which a signal of a certain track is mixed with a signal of an adjacent track when reproduction is attempted. Also, the influence of crosstalk increases due to an increase in the aperture beam diameter due to a shift in focus control, or a distortion in the beam shape due to a tilt of the disk with respect to the optical head.

However, when the amount of crosstalk increases, the reproduction signal recorded on the adjacent track is mixed in the reproduction signal of the unrecorded sector, and the data mark is identified from the crosstalk signal. As a result, the demodulation circuit may be activated and behave as if the data of the sector was reproduced. In such a state, the reliability of data management in sector units is significantly reduced.

The present invention addresses this problem by providing a recording / reproducing method for improving the reliability of data reproduction, in which unrecorded sectors are not processed as if a signal were present and reproduced due to crosstalk. The purpose is to provide.

Means for Solving the Problems The present invention has a sector ID portion including track address information and sector address information, and a data field portion for recording and reproducing data. The data field portion includes a synchronization pull-in at the head of a data group to be recorded. In the recording method of recording at least one or more synchronization signals for identifying the beginning of each data, and recording the data on the disk, a part of the pattern of the format of the adjacent track is used. A data recording / reproducing method characterized in that it is configured differently.

According to the present invention, with the above-described configuration, highly reliable data reproduction can be performed in an unrecorded sector without erroneously performing data reproduction processing due to the influence of crosstalk from an adjacent track.

Embodiment Next, the configuration and operation of an embodiment of the present invention will be described with reference to the drawings.

In order to avoid the influence of crosstalk caused by adjacent tracks, the data format may be changed at least every other track. In this embodiment, it is determined whether the track address of the target sector set when reproducing data is an odd number or an even number, and a data format is selected according to the result to perform modulation and demodulation.

FIG. 1 shows a data recording / reproducing format in one embodiment of the present invention. FIG. A shows the format of an odd track, and FIG. B shows the format of an even track. As shown in the figure, the length of the gap A between the sector ID part and the data field part is different between FIGS. In the figure, odd track gap A6
The gap A6 'of the even track is longer, but may be set in reverse. In FIG. B, the gap B may be shortened by the length of the gap A as compared with FIG. A, and the intervals between IDs may be made the same.

FIG. 2 shows a block diagram of a modulation circuit of a data recording / reproducing method according to one embodiment of the present invention. A reproduction signal 100 read from the optical disk 8 by the photodetector 9 and amplified by the preamplifier 10 is subjected to waveform shaping by a waveform equalization circuit 11 and digitized by a comparator 12 to become a binary reproduction signal 101. On the other hand, the address of the sector ID portion is
, And a sector address reproduction signal 102 is output. When modulating the data of a certain sector, the CPU 14 that controls the control checks the address reproduction signal 102, sets the track address and the sector address of the target sector in the track address (TA) and sector address (SA) setting circuit 15, and modulates the data. The modulation command signal 105 is sent to the modulation timing control unit 17 that controls the timing of the time. In the odd / even judgment circuit 16,
The address read from the ID portion of the address reproduction signal 102 is compared with the address 103 set by the CPU, and if they match, the target sector detection signal 104 is sent to the modulation timing control unit 17. At this time, the generation timing of the detection signal 104 is changed by the odd / even judgment circuit depending on whether the track is odd or even. This target sector detection signal 104 and the aforementioned modulation command signal 1
The modulation section is activated by 05, and the entire modulation sequence is executed. The modulation timing control unit 17 sends a control gate signal 106 to each unit to generate one sector of recording data. The control gate signal 106 is supplied to a SYNC generator 18 for generating a SYNC pattern, a DM / RS generator 19 for generating a pattern of a data mark DM and a resynchronization signal RS, and a data modulator 20 for performing modulation by a data input signal 107 to be recorded. The output of each block is selected by selector A21,
The data is sent to a laser drive circuit (not shown) as formatted one-sector recording data 108.

Next, a demodulation circuit of a data recording / reproducing method according to an embodiment of the present invention will be described with reference to FIG. As described in the modulation circuit, when reproducing the data of the target sector, the CPU 14 first sets the track address and the sector address of the target sector in the TA / SA setting circuit 15 and controls the demodulation timing. The demodulation command signal 110 is sent to the timing controller 25. The odd / even judgment circuit 16 compares the address read from the ID portion of the address reproduction signal 102 with the address 103 set by the CPU, and sends a target sector detection signal 109 to the demodulation timing control unit 25 if they match. Further, the binary reproduction signal 101 is reproduced clock by the PLL circuit 22.
111 is generated by itself, and a demodulation operation is performed in accordance with the reproduced clock 111. In the data mark detection circuit 23 and the resynchronization signal detection circuit 24, when a data mark and a resynchronization reproduction bit pattern appear in the input binary reproduction signal 101, the data mark detection signal 112 (hereinafter referred to as a DM detection signal) ), And outputs an RS detection signal 113. Further, a mask signal 115 is generated from the detection gate 26 by the target sector detection signal 109 so that the DM detection signal and the RS detection signal are not erroneously detected in the data by the demodulation timing control unit 25, and the DM detection signal 112 and the RS detection signal 113 are generated. On the other hand, masking is performed by AND circuits 27 and 28, respectively. The demodulation timing control unit 25 outputs a demodulation timing gate signal 114 to the demodulation unit 29 in frame units according to these signals, and outputs a demodulation signal 116 from the demodulation unit, thereby completing the entire demodulation sequence.

By configuring the format pattern differently between adjacent tracks in this way, even if there is an effect of crosstalk from the adjacent track when trying to reproduce an unrecorded sector, the synchronization signal on that track is Is not detected, and the demodulation timing gate signal 114 is not output. Therefore, data reproduction processing is not performed erroneously due to crosstalk in unrecorded sectors.

In the present embodiment, the format pattern is selected by the odd / even judgment signal of the track address set by the CPU, but it goes without saying that the CPU may directly select the format pattern together with the setting of the track address. In the present embodiment, the data recording format having two types of synchronization signals of the data mark DM and the resynchronization signal RS2 in one sector has been described. However, the same applies to the data recording format having only one type of synchronization signal. is there.

As described above, according to the present invention, a format signal is configured to be different between adjacent tracks, and a synchronization signal (data mark DM) for identifying the head of data is provided.
By setting the detection timing of the resynchronization signal RS to be different, it is possible to prevent a state in which a signal is present in an unrecorded sector due to crosstalk and data reproduction is performed. The reliability of data recording and reproduction can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a data recording / reproducing format diagram in one embodiment of the present invention, FIG. 2 is a block diagram of a modulation circuit in one embodiment of the present invention, and FIG. 3 is a block diagram of a demodulating circuit in one embodiment of the present invention. FIG. 4 is a conventional data recording / reproducing format diagram. 1... Synchronization pull-in signal, 2... Data mark, 3.
Resynchronization signal, 4 ... data section, 5 ... sector ID section, 6,
6 ': gap A, 7, 7': gap B.

Claims (2)

(57) [Claims] 1. One sector on a recording medium having a sector structure has a sector ID section containing track address information and sector address information and a data field section for recording and reproducing data, and the data field section is synchronized. The recording position of the synchronization signal in the data field part is different from the sector ID part in the adjacent track consisting of the synchronization pull-in signal for data, at least one synchronization signal for identifying the head of data, and data. Wherein the timing of a detection gate for detecting a synchronizing signal is different depending on the data recording / reproducing method. 2. The data recording / reproducing method according to claim 1, wherein the recording position of the synchronization signal is different between odd / even tracks.