JPS58158041A - Optical information recording method - Google Patents

Abstract

PURPOSE:To eliminate the distortions of reproduced signals and to obtain optimum bit widths and edge shapes in consideration for the characteristics, etc. of photoresist, by correcting slightly the periods when the light beam modulated according to information is strong and weak. CONSTITUTION:A one-shot circuit 4 is driven in response to the fall of an information signal (a), and a correction pulse (b) of a specified width is outputted. The signal (a) and the pulse (b) are converted to an inverted signal (d) with an adder 5 and an inverting circuit 6. Bits are formed on a disc by the signal (d). If the signal is modulated and recorded in such a way that the period when the signal (d) is a high level is the period when the intensity of the recording laser beam is strong, said signal is made into the signal expanded by twice in said high level period, which signal corresponds to the low level period of the original recording signal (a). In other words, the duty ratio of the reproduced signal is the same as the duty ratio of the recording signal.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of optically recording ζ2 information using, for example, a laser beam, and more faithful reproduction of information signals! It is completely possible.

Recently, in response to information signals such as the Eirin signal and the back door signal, the laser beam Y light has been changed, and this changed laser beam disk [?Site type photoresist (11 is uniformly Glass substrate being coated (2)
[Refer to Figure $1] Title: Forming a concavo-convex pattern (bit) on this disc by irradiating it and then performing a rolling process etc. From ζ2, it is proposed to record information. (for example, disclosed in Japanese Patent Application Laid-open No. 123905/1983), and using this disc as a master,
Information recording discs are manufactured by T's.

Incidentally, the relationship between the optical laser beam and the 62 pitches recorded on the disk is as shown in FIG. 1C.

Figure 1 (1) shows the intensity distribution of the laser beam when focused on the disk (this is close to the glass distribution), and the horizontal axis shows the diameter of the laser beam. . Figure 1 (1G) shows the shape of the bit obtained after undergoing the processing step, (111) is a photoresist of a predetermined thickness) The scale indicates the threshold of light intensity of the photoresist (1). The bit width and edge shape are determined by Ily)(;.

Now, let us consider recording the digital information signal shown in Figure 2 (&row). If we modulate the laser beam with this information signal, the recording laser beam will have an intensity distribution l as shown in Figure 2. can get. Corresponding to this recording laser beam, bits as shown in Figure 2 (0roni) are formed on the disk. When information is reproduced from a disk having such bits, the reproduced signal becomes a complete rectangular wave. However, by shaping the waveform, a reproduced signal as shown in Figure 2 (d) (=) can be obtained. This reproduced signal ((11v recording signal (
Compared to a), the high level period is the playback signal (+1
) is 2t.

You can see that it is getting longer. That is, the reproduced signal + (1
The duty of 1 is different from the information signal, and distortion will occur. This is due to the recording laser beam.
Although it is possible to eliminate these disadvantages, doing so would result in disadvantages such as the bit width becoming smaller and the shape of the edge of the bit becoming less favorable.

Therefore, in the present invention, the period of strength of the original beam modulated according to the information! , the above-mentioned inconvenience is attempted to be resolved by making some corrections.

The following description will be made with reference to FIG. 3 showing a block diagram of an apparatus for implementing the present invention, and FIG. 4 showing its operating waveform diagram.

The information signal to be recorded (fourth
1) is generated, but in response to the fall of this information signal (al), the one-V Yoyto circuit (4) is driven, and as shown in FIG.
1) 11--A correction pulse of a constant width (tl) as shown is output. This width t1 is tt==2to.
The information signal (1) and the correction pulse +1)l are connected to the adder circuit (5
1, and the result of the addition (FIG. 4 0) is applied to the t' inversion circuit (6) to obtain an inverted signal (FIG. 4 d).

This signal (ill) changes the recording laser beam to form a beam on the disk. Thus, a bit concave portion is formed corresponding to the high level period (for example, TO) of the signal (11) (i.e., the high level period of the signal (+1) becomes the intense luminous intensity period of the recording laser beam. If it is modulated and recorded, the reproduced signal becomes a signal extended by tl (=2t6), which corresponds to the low level period (〒1) of the original recording signal (al). That is, The duty ratio of the reproduced signal is the same as that of the recorded signal.

In the case of Fig. 4, the low level period of the recording signal e) corresponds to the high intensity period of the recording laser beam, so the positive/negative logic of the reproduced signal is the same as in the case of Fig. 112, but the positive/negative logic of the reproduced signal By inverting the logic, a signal similar to that shown in Figure 1 can be obtained.

In the above-described embodiment, recording was performed on a master disc coated with a photosensitive photoresist, but it is of course also applicable to cases where optically recordable metal materials, inorganic materials, resins, etc. are used. Of course, the width of the correction pulse varies depending on the recording material.

Furthermore, it is no problem to drive the one-V, one-V, and 7-to-7 circuits in response to the rising edge.

According to the present invention I described above, when recording using the original beam, the intensity period of the light beam modulated according to information is corrected based on the intensity I distribution of the party beam, so that Distortion t of the reproduced signal can be eliminated. Therefore, the light intensity CBB)(E!) can be determined so as to obtain the optimum bit width and edge shape, taking into consideration the characteristics of the photoresist.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the relationship between the original beam and the bits, Figure 2 is a diagram explaining the conventional recording method, Figure 183 is a block diagram of a device for realizing the method according to the present invention,
FIG. 4 is a diagram for explaining the recording method of the present invention. (31 is a recording information generation circuit, (4) is a one-shot circuit, (5) is an addition circuit, and (6) is an inversion circuit.

Claims (1)

[Claims] (1) To record information to be recorded; irradiate the information recording medium C with a modulated light beam to form a pattern 1 on the information recording medium corresponding to changes in the light intensity of the light beam.
′: Method C of recording information from the above information (2): an optical information recording characterized in that the information is corrected based on the intensity distribution of the light beam; Method.