JPS62110637A - Information recording medium - Google Patents

Abstract

PURPOSE:To increase reflectivity of pregrooves and to permit the reproduction and detection of a normal address signal by providing auxiliary guide tracks having the same reflectivity as the reflectivity of address pit parts for a desired section before and behind the address pit parts. CONSTITUTION:The auxiliary pregroove sections 42 are provided between the pregroove section 2 and the address part 6 for desired sections before and behind the address part 6. The width of the grooves 42 is made equal to the width of the address pits. The reflectivities of the grooves 42 and the address pit part are therefore made equal and the reproduction and detection of the normal address signal for the first pit and final pit of the address pit part are thus made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to the structure of information tracks on a disk-shaped record carrier (hereinafter referred to as a disk) for optically recording and reproducing images, audio, digital data, etc. υ, particularly relates to the structure of a disc having a guide track (hereinafter abbreviated as pre-group) of a recordable disc and an address signal provided together with the pre-group.

BACKGROUND OF THE INVENTION FIG. 5 shows an example of the structure of a conventionally used recordable disc. In FIG. 5, 1 is a disk, 2 is a pre-group, and 3 to 6 are address signals provided once per round of the pre-group, indicating the address of the pre-group. FIG. 5 also shows an enlarged view of the address signal, in which the address signal is constructed by intermittent pre-group 2.

The pre-group and address signals 3 to 6 are generally provided at a pitch of about 1.6 microns, and their width is about 0.6 microns.
It is configured as a fine convex portion or concave portion of 7 microns and a height of approximately 0.08 microns.

FIG. 6 is an enlarged view of the signal pits and address signal pits recorded in the pre-group. By irradiating the pre-group 2 with a laser beam modulated by the signal to be recorded, recorded signal pits 11 are obtained. This signal pit is recorded as a change in reflectance of the recording layer provided in the pregroup 2, for example. On the other hand, address signals 3 to 6 are constructed by interrupting pregroup 2. The reproduction laser spot for reproducing the recorded signal pit and address signal focus is set to 1.
Shown in 2.

As another conventional example, as shown in Japanese Patent Application No. 59-185603, a method has been proposed in which address sections are arranged in a staggered manner in order to reduce crosstalk between adjacent address sections. An example of this configuration is shown in FIG. In FIG. 7, pregroup P1 has an address signal bit 32 in the address section 30, and the next pregroup P2 has an address signal bit in the address section 34 of section 31. Hereinafter, as shown in the figure, the address signal 33 of the next pre-group P5 is set in section 30, and the address signal 35 of pre-group P4 is set in section 31, so that the address signals are not adjacent to each other.

Problems to be Solved by the Invention However, in recent years, with respect to these conventional disk configurations,
There is a demand for high S/N of recorded and reproduced images, and it is necessary to increase the amount of reflected light from the pre-group.

In order to increase the amount of light reflected from the pre-group, it is necessary to reduce the diffraction loss of the reproduction spot due to the pre-group.

FIG. 8 shows the relationship between the amount of reflected light and the pregroup line width. As is clear from FIG. 8, in order to increase the amount of light reflected from the pre-group, it is necessary to make the pre-group width wider or narrower than the pitch.

When recording between pregroups without recording on pregroups, the reflectance is 100%, but when considering compatibility with conventional discs, there are problems such as the need to switch the tracking polarity. has.

Figure 9(a) shows the reflectance change when the conventional pregroup width and address bit width are almost equal, and the reflectance change when the address bit width is the same as before and the pregroup width is narrowed and widened. (11, shown in (C). (a
) is for the case where the pre-group width and the address signal focus width are equal, and the reflectance of the pre-group and address signal pit is equal, and the reflectance is high in the land between the pre-group and the address pit, and the address signal There is no problem with playback detection.

(b) and (0) are cases where the bit width of the address signal is the same as the conventional one, but the pregroup width is narrower or wider. This example shows a case where the reflectances from the pregroups (i and (C)) are equal.

In this case, the reflectance of the pre-group and the reflectance of the address pit are different between the first focus and the last pit in the address pit area, and the reflectance of the pre-group is high, making it impossible to detect address signal playback. There is a problem with this.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention aims to provide a method for configuring an optical disc in which the reflectance of the pre-group is increased and no problem occurs in address signal reproduction detection.

Means for Solving the Problems In order to solve the above-mentioned problems, the configuration of the optical disc of the present invention provides a first optical disc having a reflectance approximately equal to the focus width of the address signal over a desired section before and after the address signal section. ．． It has a configuration including a second sub-guide track (sub-pregroup section).

Effect: With the above-described configuration, the reflectance of the sub-pregroup portion and the address pit portion are equalized over the desired section, and problems with address signal reproduction detection are not caused.
5. Reproduction detection can be performed accurately.

Example FIG. 1 shows an example of the configuration of the present invention.

Between the pre-group section 2 and the address section 6, sub-pre-group sections 42 are provided as desired sections before and after the address section 6. The width of this sub-pre-group 42 and the width of the address pit are configured to be approximately equal.

For this reason, the reflectance of the sub-pre-group 42 and the address via section becomes equal, and as shown in the change in reflectance shown in FIG. Detection becomes possible.

The sub-pregroup section before the address part should be set to a desired value depending on the rotation speed of the optical disc, the disc diameter, etc., as well as the time constant of the clamp circuit of the address detection system, and should be set to a desired value of several microseconds to 100 microseconds. That's about it.

However, the sub-pregroup section after the address section only needs to detect the final pit of the address section normally, and is preferably shorter than the second group section before the address section.

Also, depending on how you choose the pregroup width and address width,
As shown in FIG. 3, it has been experimentally confirmed that the reproduction level at the output of the signal detection circuit fluctuates due to a sudden change in reflectance at the boundary between the first and second sub-pre-groups.

Another embodiment of the present invention for solving such problems is shown in FIG.

Between the pre-group section 2 and the address section 6, a first sub-pre-group section 42 and a second sub-pre-group section 44 are provided in desired sections before and after the address section 6. This second
The above problem can be solved by configuring the width of the secondary pre-group and the width of the first secondary pre-group to vary substantially continuously.

Although the embodiments of the present invention have been described using embodiments having different groove widths, the reflectance of the pregroup also changes depending on the phase difference. Further, the reflectance of the recording medium varies depending on the reflectance of the recording degree, but all of them are included as long as the same effects as the present invention can be obtained.

Effects of the Invention As described above, according to the present invention, an optical disc having a configuration in which the pregroup width is narrowed or widened in order to increase the reflectance of the pregroup is compatible with the conventional address reproduction signal output. However, it is possible to obtain an optical disc that does not cause any problem in address reproduction signal detection.

The present invention is applicable not only to address sections configured in a staggered manner, but also to optical discs configured such that the pregroup width and address bit width are different. Further, as for the second sub-pre-group, any configuration can be applied as long as the pre-group width and address bit width are approximately continuously changed.

[Brief explanation of drawings]

FIG. 1 is a plan view showing the structure of an information recording carrier in an embodiment of the present invention, FIG. 2 is a waveform diagram showing changes in reflectance,
FIG. 3 is a waveform diagram showing the reproduced signal waveform, FIG. 4 is a plan view showing the configuration of an information recording carrier in another embodiment of the present invention, and FIG. 5 is a diagram showing the configuration of a conventional information recording carrier. 6 is a plan view of the vicinity of the address portion, FIG. 7 is a plan view of another example of the conventional disk, FIG. 8 is a characteristic diagram showing the relationship between groove width and reflectance, and FIG. 9 2A and 2B are a plan view and a waveform diagram showing changes in reflectance when the address bit width is constant and the pregroup width is varied. 1. Disc, 2. Pre-group, 3~6°32~
35...address part, 11...recorded information pit,
12...Reproduction laser spot, 42...First sub-pre group, 44...Second sub-pre group. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Figure Hill Closed Figure 3 Figure 1--Tensuf Figure 5

2--Ali'7'11. -73 ~ G

Claims (4)

[Claims] (1) An information recording carrier that stores predetermined information in an optically readable form, and has a guide track that acts as a guide for recording optically readable information and information such as an address. In the information recording carrier having an address pit portion, the guide track and the address pit portion have different groove widths and phase depths, and have different reflectances, the address pit portion is provided over a desired section before and after the address pit portion. An information recording carrier characterized in that it has first and second sub-guide tracks having substantially the same reflectance as that of the first and second sub-guide tracks. (2) The second sub-guide track section located after the address pit section is shorter than the first sub-guide track section located before the address pit section. Information record carrier. (3) The information recording carrier according to claim 1 or 2, characterized in that the reflectance of the second sub-guide track section is changed almost continuously. (4) Claims 1 and 2, characterized in that the guide track and the second auxiliary guide track are configured continuously.
The information recording carrier according to item or item 3.