JPH025247A - Information recording medium - Google Patents

Abstract

PURPOSE:To decrease an error rate and to allow high-density recording by providing parts for suppressing diffusion of heat provided at prescribed periods in the longitudinal direction of data tracks thereby easily controlling data length and shortening bit length. CONSTITUTION:The parts which suppress the diffusion of heat, i.e. the grooves 12 are provided at the prescribed periods in the longitudinal direction of the data tracks 11. The data tracks 11 are made to have thermally discontinuous surfaces by the grooves 12 and the pitches of the grooves 12 are set shorter than the shortest bit length. The diffusion of the heat of a laser beam for recording is hindered by the grooves 12 when the data tracks 11 are irradiated with the laser beam. The diffusion of the heat is thus limited to the regions 13 and the regions 13 form recording bits. The control of the data length is possible in this way and the error rate is decreased; in addition, the bit length is shortened and the high-density recording is feasible.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a heat mode type information recording medium.

[Conventional technology]

In recent years, so-called heat mode recording has been put into practical use, in which information given by light, for example, is converted into the form of thermal energy and then applied to record changes in the shape or physical properties of a recording material.

FIG. 5 shows an enlarged perspective view of a part of a conventional heat mode type information recording medium. In the figure, 1 is a strip-shaped data track, 2 is a guide groove for tracking, and 3 is a recording bit. In the medium, for example, when a recording laser beam is irradiated onto the data track 1 as shown by the broken line in FIG. 6, the heat from the laser beam is diffused to the area 5 shown by diagonal lines in the figure, and this area 5 is used as the recording bit. becomes. Information is read by irradiating the bits thus formed with a reading laser beam and detecting the level of the reflected light. The level of the read signal at this time is shown in FIG. 7, where LTH is a determination level, and the length of the portion where the reflectance has decreased below this level is the data length. Further, FIG. 8 shows the distribution of data length when beam irradiation is repeated for a certain period of time.

[Problem to be solved by the invention]

The conventional information recording medium has a problem in that it is difficult to control the shape of the bits. That is, Figures 6 and 7
As shown in the figure, the bit length was longer than the data length, and the data length was also uneven as shown in FIG. This tendency becomes more pronounced when the thermal conductivity of the recording material is high.

This causes an increase in the error rate and also prevents high-density recording.

In view of the above points, it is an object of the present invention to provide an information recording medium in which the data length can be easily controlled, the bit length can be shortened, the error rate can be reduced, and high-density recording can be performed.

[Means to solve the problem]

In order to achieve the above object, the present invention provides an information recording medium in which recording is performed in bits by applying thermal energy onto a band-shaped data track, in which heat is diffused at a predetermined period in the longitudinal direction of the data track. An information recording medium is provided that is characterized by being provided with a suppressing portion.

[For production]

The heat diffusion suppressing portions provided at predetermined intervals in the longitudinal direction of the data track limit the diffusion of thermal energy given by irradiation with a laser beam, etc., within a certain area, and keep the data length consistent with the bit length. It acts to give. Therefore, it becomes possible to shorten the bit length and control the data length, thereby solving the above-mentioned problems.

(Example〕 The present invention will be explained in detail below using examples.

FIG. 1 is an enlarged perspective view showing the structure of the data track in the information recording medium of this embodiment. In FIG. shows.

The data track 11 is formed into a thermally discontinuous surface by the groove 12 . The pitch of the grooves 12 is set shorter than the shortest bit length.

When the data track 11 is irradiated with a recording laser beam as shown by the broken line in FIG. 2, the heat is diffused;
Heat diffusion is prevented by the groove 12 and does not spread to sections other than the data track section irradiated with the laser beam.
In other words, the area where the heat diffuses is the shaded area 1 in Figure 2.
3, and this area 13 becomes the recording bit.

FIG. 3 shows the signal level when the recorded bits in FIG. 2 are read. Note that LTH in the figure is a determination level. As shown in the figure, although there is a regular increase in reflectance due to the grooves 12, this can be ignored.

The length of the portion where the reflectance has decreased below the determination level LTH, that is, the data length, matches the bit length. Also.

FIG. 4 shows the data length distribution when beam irradiation is repeated for a certain period of time, and the data length distribution in this embodiment is a narrow distribution with an error equal to the pitch of the grooves 12.

As described above, when the data track 11 is made thermally discontinuous at a constant period, the bit length becomes shorter and the data length becomes approximately constant.

In the above embodiment, the data track 11 is made thermally discontinuous at a constant period by the groove 12, but the same effect can be obtained by using a convex portion formed across the data track 11 instead of the groove 12. Obtainable.

〔Effect of the invention〕

As explained in detail above, according to one aspect of the present invention, parts for suppressing heat diffusion are provided at predetermined intervals in the longitudinal direction of the data track, making it possible to control the data length and reduce the error rate. I can do it.

Furthermore, by shortening the bit length, high-density recording becomes possible.

[Brief explanation of the drawing]

FIG. 1 is an enlarged perspective view showing the structure of a data track of an information recording medium according to the present invention, FIG. 2 is a diagram showing how bits are formed on the data track of FIG. 1, and FIG.
FIG. 4 is a diagram showing the data length distribution in the information recording medium according to the present invention. FIG. 5 is a diagram showing a part of the conventional information recording medium. An enlarged perspective view, FIG. 6 is a diagram showing how bits are formed on the data track of FIG. 5, and FIG.
FIG. 8 is a diagram showing the signal level when information is read from the data track shown in the figure, and FIG. 8 is a diagram showing the data length distribution in a conventional information recording medium. 11...Data track, 12...Groove, 13...
・Area where heat is diffused (bit) Figure 3 Figure 4 Data length Figure 7 Figure 8 Data table

Claims (1)

[Claims] (1) An information recording medium in which recording is performed in bits by applying thermal energy onto a band-shaped data track, characterized in that portions for suppressing heat diffusion are provided at predetermined intervals in the longitudinal direction of the data track. information recording medium.