JPS61208630A - Optical disc - Google Patents

Abstract

PURPOSE:To attain recording of a signal with large recording laser power margin to a disc by recording a modulation signal and an edge pulse signal of a sector ID section and making the minimum recording interval of recording dots of the sector ID section equal to that of a data field section. CONSTITUTION:When a minimum recording dot interval Timin of the sector ID section 3 and a minimum recording dot interval Tdmin of the data field section 4 are set to equal values in a recording dot 9, it is advantageous that the differentiation time constant of a differentiation circuit and a cut-off frequency of an LPF are made identical in applying detection differentiatingly to a reproducing signal 10. This results in making the reproduction signal processing system simple so as to decrease number of adjusted parts. Further, a modulation signal of the sector ID section is modulated by the modulation system facilitating the clock reproduction including the clock pulse at each bit cell and the bit error rate of the sector ID section is improved than that of the data field section by setting lower the bit rate than that of the data field section. Thus, the reproducing signal processing system is simplified and the accuracy of count of the number of traversing tracks is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an optical disk applied to, for example, an optical disk memory, and particularly to an optical disk with increased signal recording margin.

2. Prior Art Conventional optical discs include, for example, Japanese Patent Application Laid-open No. 1725-1983.
This is shown in Publication No. 33. FIG. 3 shows a conventional example of an optical disc recording signal. In FIG. 3a, the grooved guide track 1 is divided into a plurality of sectors 2. In FIG. Each sector 2 is composed of a sector ID section 3 in which sector identification information such as a track address and sector address is recorded, a data field section 4 in which data is recorded, and gaps 5 and 6 for absorbing rotational fluctuations of the disk. Generally, sector ID part 3
is recorded in advance when forming the groove-shaped guide track 1. Third
The figure is a partially enlarged view of the modulated signal 12 of the sector ID section 3, gap 5, and data field section 4. Modulation signal 12
For example, GCR (PEPhase Encoding) is a modulation method that allows easy clock reproduction of the sector ID part and is strong against errors.
Group Code Recording), RLLC
(Run Length Lim1ttedCode
), and recorded dot 1 shown in Figure 3C
Recorded as 3. The recording dots 13 record the modulated signal 12
In FIG. 3C, 13& is a sector ID section recorded in the form of uneven pits, and 13b is a data field section recorded in the form of dark and light dots. FIG. 3d shows the reproduced signal 14 from the recording dot 13.

Figure 3e shows the reproduced signal 14 at a clipping level of 16.
The amplitude detection signal 16 is converted into a value. Problems to be Solved by the Invention However, considerable fluctuations in recording dots occur during pre-formatting of the 10 sectors and during recording of the data field. This is due to variations in the sensitivity of the recording medium,
These include changes in laser light output, focus servo accuracy, accuracy of recording laser power level correction with respect to circumferential speed in the disk radial direction, and so on. Changes in recording dot size generate second harmonic distortion. This causes time fluctuations, so-called jitter, in the rising and falling edge portions of the reproduced signal.

FIG. 4 is a diagram illustrating the above-mentioned jitter generation process.The 0 recording signal 12 (FIG. 4a) is small and appropriate.

When recording is performed with three excessive recording laser power levels, the reproduced signals 14 shown in FIG. 4, a and d are produced, respectively. The reproduced signal 14 is binarized at a clipping level 1e and becomes an amplitude detection signal 15.The amplitude detection signal 16 generates jitter of ΔTj shown by a broken line due to a change in recording laser power.

This jitter has the problem of narrowing the detection window margin when demodulating the reproduced signal 14. Also, sector I
Since the modulation methods for the D section and the data field section are different, there are problems such as two systems of binarization circuits and waveform equalization circuits for the reproduced signal 14.

In view of the above, an object of the present invention is to provide an optical disc that enables signal recording with less jitter in a reproduced signal and a large recording laser power margin on the disc. , an optical disk with a sector structure consisting of a preformatted sector ID section and a data field section in which data is recorded, recording edge pulse signals of the rising edge and falling edge of the modulated signal in the sector ID section and the modulated signal in the data field section. However, the minimum recording interval of these recording dots is sector 1.
This is an optical disc in which the 0th part and the data field part are the same. Furthermore, the optical disc is characterized in that the bit rate of the modulation signal in the sector ID section is lower than the bit rate of the modulation signal in the data field section.

Function: With the above-described configuration, the present invention records the changing point of the modulation signal in the sector ID section or the data field section, so that even if the recording conditions represented by the recording laser power change, the peak position of the reproduced signal does not change. In particular, playback without jitter can be performed.

Furthermore, by making the minimum recording dot spacing of the sector ID section and the data field section the same, it is possible to process the reproduction ID signal and the reproduction data signal by the same filter and waveform equalization circuit. This figure shows the format and signal waveform of an optical disc in one embodiment of the present invention.
The grooved guide track 1 is divided into a plurality of sectors 2. Sector 2 has a sector ID section 3, a data field section 4, and gaps 5 and 6. Figure 1a shows the entire signal reproduced from the track. Figure 1 shows the modulated signal 7 in the sector ID section and data field section. The modulated signal 7 is converted into the recording signal 8 shown in FIG. 1C by its rising and falling edges.
This recording signal 8 is recorded as a recording dot 9 shown in FIG. 1d.

In FIG. 1 d17c, the track 1 is recorded in such a way that the recording dot 9 is convex in the sector ID part 3, that is, the recording signal 8 is at a low level, and the data field part 4 is formed in the form of a uniform groove with a constant depth. It is recorded as a change in density on the track. This is to reduce counting errors in the sector ID section when counting the number of crossing tracks during a search. ◇A groove is required to detect crossing tracks from the 71-field of guide track 1. Figure 1 e shows the recording. This is a reproduced signal 1o resulting from the reflected light from the dot 9.

The recording signal 8 is converted into a predetermined pulse width signal by detecting the change point of the modulation signal 7. The pulse widths Ti and Td are the recording pulse widths of the sector ID section and data field section. Recording medium during pre-formatting (generally photoresist is used, and a replica is taken by a so-called master limp process) and optical disk recording medium (generally a tellurium compound)
Ti and Td are set depending on the difference in the recording/reproducing characteristics of shows.

In Fig. 2, the recording laser power is small at a, d, and e.
The reproduced signal 1o in the case of appropriate and excessive values is shown.

Note that Fig. 2a shows the modulated signal 7, and Fig. 2 shows the recording signal 8.◇If the recording laser power is small or excessive, the amplitude change of the reproduced signal 1o will be small, and the signal resolution will be reduced. ◇FIG. 2 f shows the differential detection signal 11 obtained by differentially detecting the peak value of the reproduced signal 1o. Differential detection signal 11
Since the peak value of the reproduced signal 10 is detected, positional deviation due to changes in recording laser power, that is, jitter does not occur.

This is because a change in the recording laser power only changes the size of the recording dot, but does not change the center position of the dot.

The recording dot 9 is the minimum recording dot interval T of the sector ID section 3.
1 m1 and the minimum recording dot interval Tdxnin of the data field section 4 are set to the same value. By doing so, the differential time constant of the differentiating circuit and the cutoff frequency of the LPF can be made the same when performing differential detection from the reproduced signal 10. This simplifies the reproduction signal processing system and reduces the number of adjustments.

In addition, the modulation signal in the sector ID section is modulated using a modulation method that facilitates clock recovery, including a clock pulse for each e-tell, and by setting its bit rate lower than that of the data field section, the pit error rate of the sector ID section can be reduced by setting the bit rate lower than that of the data field section. According to this embodiment, the recording signal of a predetermined pulse width is generated from the rising and falling edge parts of the modulation signal of the sector ID part and the data field part. By using K, it is possible to provide an optical disc in which signals can be detected without playback jitter during preformatting of the optical disc and data recording.
Signal processing is simplified by making the minimum recording dot spacing of the recording signal the same in the sector ID part and the data field part. In addition, the change point of the modulation signal is set in the sector ID part in the land part (
By making grooves (concave parts) other than the changing points, it is possible to improve cross-track counting errors during retrieval.As described in detail, according to the present invention, jitter is eliminated even when the recording laser power changes. 0 that can provide optical discs that do not cause
Also, the playback signal processing system has been simplified.

The practical effects are significant, such as improving the accuracy of counting the number of crossing tracks.

[Brief explanation of drawings]

Fig. 1 is a format diagram of an optical disc according to an embodiment of the present invention, Fig. 2 is a signal diagram showing the relationship between recording laser power change and reproduction signal jitter in Fig. 1, and Fig. 3 is a format diagram of a conventional optical disc. , FIG. 4 is a signal diagram showing the relationship between recording laser power change and reproduction signal jitter in FIG. 12... Recording signal, 9, 13
... Recording dot, 11 ... Differential detection signal, 16 ... Amplitude detection signal. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3 Figure 4

Claims (3)

[Claims] (1) It has a groove-shaped guide track, the guide track is divided into a plurality of sectors, and the sector is composed of a sector ID part in which address information is pre-formed and a data field part in which data is recorded, and the sector ID A recording signal having a predetermined pulse width generated from a change point of a modulated signal modulated by a different modulation method is recorded in the sector ID part and the data field part, respectively, and the minimum interval between recording dots in the sector ID part and the data field part is An optical disc characterized by being recorded equally. (2) The optical disc according to claim 1, wherein the bit rate of the modulation signal of the selector ID section is lower than the bit rate of the data field section. (3) The optical disc according to claim 1, wherein the sector ID portion is such that the recording signal corresponding to the change point of the modulation signal is a land portion, and the portion other than the change point is a groove portion.