KR100198558B1 - Phase transition type optical disk - Google Patents

Abstract

In the phase change type optical disk, in particular, the height difference between the land and the groove is converted into the height difference that minimizes the optical noise, and the width of the land and the groove are narrowed to be equal to the width of the recording mark. Since the groove area is far away and the heat transfer between adjacent tracks is lowered when recording and erasing information, there is no distortion of the shape of the recording mark or the crosstalk phenomenon of moving the tip or the front part of the recording mark. Recording / reproducing is possible, and even if thermal deformation occurs, there is no area for the recording mark to flow, so that the jitter can be reduced by eliminating the deformation and deformation of the mark.

Description

Phase change optical disk

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phase change type optical disk, and in particular, to increase the height difference between the land (Land) and the groove (groove) and to narrow the width of the land and the groove to reduce crosstalk due to heat transfer and jitter The present invention relates to a phase change type optical disk for removing jitter.

In general, phase-change optical discs have a signal track having a structure of lands and grooves, so that tracking control can be performed on a blank disc in which no information signal is recorded, and in recent years, tracks of lands and grooves can be used to increase recording density. Each information signal is recorded in the.

To this end, the wavelength of the laser light of the optical pickup for recording / reproducing is shortened, and the numerical aperture of the objective lens for condensing is increased to reduce the size of the light beam for recording and reproducing.

That is, the phase change type optical disk concentrates the laser light on the recording film, and rapidly cools the recording film when the temperature of the recording film rises above the melting point corresponding to the light output and the pulse width, thereby making the recording film amorphous and using it as a recording bit. Unlike the above recording on the recording film, the laser beam is irradiated with a low light output and pulse width to raise the temperature of the recording film near the crystallization temperature and then cooled slowly to bring it into a crystallized state.

The information reproducing method uses a difference in reflectance in such a phase state, for example, a reflectance in a crystalline state (erased state) higher than that in an amorphous state (recording state).

Then, the laser beam is irradiated from the polycarbonate substrate side and initialized by applying a predetermined power so as to make the recording layer crystallized. In the case of information recording, the laser irradiation part is melted and then quenched to quench the amorphous spot. Make

Again, overwriting is carried out by repeating the process of returning the amorphous spot to a crystalline state by irradiating a lower laser.

FIG. 1 is a cross-sectional view showing a track structure of such a conventional phase change type optical disc, and tracks of the land 11 and groove 12 in the phase change type optical disc having the structure of the land 11 and the groove 12. At the center of the recording marks 13, recording marks 13 for recording information signals are provided.

Further, as the optical disk becomes denser, the width P1 of the land 11 and the width P1 'of the groove 12 are used to record signals in the track of the land 11 and the track of the groove 12. The rates are equal.

At this time, the width of the mark 13 is narrower than the width P1 or P1 'of the land 11 or the groove 12.

The height difference between the land 11 and the groove 12 is lambda / 6n, where lambda is the wavelength of the laser.

Here, n is the refractive index of the substrate, assuming that the medium is air, n is 1.

Accordingly, the height difference between the land 11 and the groove 12 is λ / 6.

However, the conventional phase change type optical disc described above has a small height difference (ie, lambda / 6) between land and grooves, so that the amount of heat transferred to both lands (or both grooves) when information is recorded in the grooves (or lands). In other words, due to thermal interaction and latent heat between adjacent recording marks, the shape of the recording mark is distorted or the end or front portion of the recording mark is shifted, which causes data to be recorded on the land (or groove). There was a problem that an error occurred during playback.

In addition, the width of the land or groove is wider than the width of the mark, so that when the information is recorded several times, the contraction and expansion are repeated to cause the flow of the recording mark, and the shape of the recording mark is distorted, causing jitter.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to change the height difference between the land and the groove to a height difference that minimizes the optical noise and to make the width of the land and the width of the groove equal to the width of the recording mark. This allows a phase change type optical disc to accurately record and play back to an optical disc while eliminating jitter by reducing crosstalk mixed in adjacent signal tracks by thermal interaction and eliminating changes in flow and shape of recording marks. In providing.

A feature of the phase change type optical disc according to the present invention for achieving the above object is a phase change type optical disc having a structure of lands and grooves, each having a recording mark for recording information signals on the lands and grooves. The width of the land and the groove is narrowed to be equal to the width of the recording mark, and the height difference between the adjacent land and the groove is converted into a height difference that minimizes optical noise.

1 is a cross-sectional view showing a conventional phase change type optical disk track structure.

2 is a cross-sectional view showing a track structure of a phase change optical disk according to the present invention.

3 is a graph showing the relationship between the height difference and the crosstalk between the land and the groove.

* Explanation of symbols for main parts of the drawings

11: land 12: groove

13: Record mark P2: Width of land

P2 ': groove width n: refractive index of the substrate

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a cross-sectional view showing the track structure of the phase change type optical disk according to the present invention, in which the width P2 of the land 11 and the width P2 'of the groove 12 are equal to the width of the recording mark 13. I narrowed it down to

At this time, in order to record a signal in the track of the land 11 and the track of the groove 12, the ratio of the width P2 of the land 11 and the width P2 'of the groove 12 is equal.

Therefore, since the width of the land 11 or the groove 12 and the width of the recording mark 13 are the same, there is no area to flow even if deformation occurs thermally, thereby reducing jitter generation.

The height difference between the land 11 and the groove 12 has two values in which crosstalk is minimized as shown in FIG.

That is, λ / 6n and λ / 3n.

The present invention converts the height difference between the lands 11 and the grooves 12 into λ / 3n, which is the height difference that minimizes optical noise, thereby increasing the height difference between the adjacent lands 11 and the grooves 12. .

Here, n is the refractive index of the substrate, assuming that the medium is air, n is 1.

Therefore, the height difference between the land 11 and the groove 12 is λ / 3, which causes the area of the land 11 and the groove 12 to be far apart so that the amount of heat transfer between adjacent tracks during recording and erasing of information. Is lowered.

As described above, according to the phase change type optical disk according to the present invention, by converting the height difference between the land and the groove into a height difference that minimizes the optical noise, the adjacent land and the groove area are far apart to record and erase information. Since the amount of heat transfer between adjacent tracks is reduced, the shape of the recording mark is distorted or the crosstalk phenomenon at which the end or front of the recording mark is moved is eliminated, thereby enabling data to be accurately recorded / reproduced on land or groove.

Further, by narrowing the width of the land and the width of the groove to be the same as the width of the mark, there is no area for the recording mark to flow even if it is thermally deformed, so that there is no deformation of the mark and deformation of the mark, thereby reducing jitter.

Claims (2)

In a phase change type optical disc having a structure of lands and grooves, each having a recording mark for recording information signals on the lands and grooves, the land and groove widths are narrowed to be equal to the width of the recording marks, and between adjacent lands and grooves. A phase change type optical disc, characterized by converting a height difference into a height difference that minimizes optical noise. The phase change type optical disc of claim 1, wherein the height difference between the land and the groove is a value obtained by dividing a wavelength λ by 3n (n is a refractive index of a substrate).