JPS6348617A - Recording system for optical information - Google Patents

Abstract

PURPOSE:To form pits to correct length all the time by increasing (or decreasing) the width of a recording pulse when the interval from the last pulse is wide (or narrow) by advancing (or delaying) the leading edge of the recording pulse relatively. CONSTITUTION:When the interval of the recording pulse is long, the influence of the diffused heat of the last pulse is small and an extra time for raising the temperature of a recording film is required as compared with when the interval is narrow, so that the leading edge of a formed pit is delayed and the pit becomes short. For the purpose, when the pulse interval is detected and judged to be wide and the influence of the diffused heat is small, the leading edge 23a of a pulse recorded next is advanced previously as shown by the broken line in a figure (a) to correct the time taue required to raise the time, and the pit 26 is formed to correct length. When a medium with high recording density is used, the temperature rise 21 of the recording film becomes relatively fast, the leading edge of a pit is advanced, and the pit 27 becomes long the taue, so the leading edge 21b of a pulse to be recorded next is delayed previously as shown by the broken line in a figure (d).

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical information recording method, and in particular, to an optical information recording method that can prevent variations in bit length due to conductive heat of recording pulses in advance. θ related to recording method [Prior art] As a device (hereinafter abbreviated as a disk device) for digitally recording and reproducing information on a digital recording medium (hereinafter abbreviated as a disk device), a 42
There is something like the one shown in Figure 2.

In this optical disk device. The semiconductor laser 3a is
It is excited by a recording signal modulated by the laser drive circuit 111. The modulated light output from the semiconductor laser 3a by this excitation passes through the collimating lens 3b, the beam splitter 3dg, and the objective lens 3c, and is converged onto the recording medium 1 to form pits la and record information. Methods for forming pits include drilling holes in the recording film and forming holes in the medium. Methods such as changing the crystal state to improve reflectance have been rejected.

During playback, the recording film is irradiated with a weak source that does not change, and the medium is used to irradiate it. The objective lens 3c is 1 inch smaller.

A method of recording digital information on such a medium is to detect the number of deaths by a photodiode 3f through a beam splitter 3d and an output lens 3e. There is a method to use. In this method, the recording beam has a finite diameter and exhibits a Gaussian intensity distribution, so the length of the recording pit is affected by the sensitivity of the recording film and the thermal properties of the medium. It may be shorter or longer than the pulse width of the signal.

Like this f. In the case of L, the length of the recording pit can be corrected by recording with the recording pulse width longer or shorter in advance. A conventional example disclosing such a technique is t# Publication No. 59-24452.

However, when the recording density is high, the effect of heat conduction becomes 5, I
This phenomenon becomes noticeable, and various distortions occur in the recorded pits. 37 (a) to (C) are diagrams schematically showing the recording signal (a), the increase in the recording film (b), and the formed pitch (c).

When the laser source is modulated by the recording sJS method (a),
The temperature of the recording film increases according to the irradiation power, but the temperature distribution (b) increases 21 because the intensity distribution of the beam spot has a Gaussian distribution and because of heat diffusion.

The descent 22 becomes gentle. Also, when the medium moves at high speed, such as with an optical disk, heat spreads.

A larger amount flows out to the rear, resulting in a gentler temperature change during the temperature rise 21 and the temperature fall 22.

Therefore, as the recording density becomes higher and the pulse interval becomes shorter, the effect of diffusion heat from the bit recorded immediately before appears. Temperature 2 King and [Temperature rise when the interval is long 23]
The difference is up to you. That is, the change in IJ value of the recording film is 2bl.
On the other hand, the length of the pit 26 formed is τ longer than the predetermined pit length when the interval between the pulses immediately preceding the pulse forming this bit is long. On the other hand, as shown in the same figure (,), when the sensitivity of the recording film is high and the change threshold 2d is low (ha).

As shown in FIG. 6(f), when the pulse interval is repeated, an error occurs in S such that the pit 27 becomes longer by τ6.

Under such high recording density, the distortion in the bit length that is formed is not unique, but changes depending on the past history such as the interval between the previous recording pulse and the like.

In conventional optical information recording devices, this point was not taken into account, and the recording pit length (this) was non-linearly shortened and expanded.Especially in write-once type original disk devices. In this case, the diameter of the optical spot for recording is large, and the above-mentioned problems are likely to occur.

An object of the present invention is to provide a recording system for optical information that corrects such pit length distortion and always forms pits with the correct length.

[Means for solving problems]

The purpose of this is to provide an optical information recording device with a means for detecting the interval between recording pulses and a means for shortening or expanding the recording pulse width. Or if it is narrow] fko.

This is achieved by advancing (or delaying) the leading edge of the recording pulse by relative tC and widening the pulse width (or turning it on and off). [Operation] If the interval between recording pulses is long, s Direct 1 (The effect of the diffusion heat of the IJ pulse is /J%. When the spacing is narrow, the increase in the recording film is 1', and as a result, the formation of The front edge of the pit is delayed and the pit is shortened. Therefore, when the pulse interval is detected and the effect of diffusion heat is small, it is possible to detect the pulse interval as shown in Figure 3 (aJ
As shown by the dashed line, the previous edge 2 of the pulse recorded next.
It's all about 4i, which advances 3g in advance.

The rising time τ. By correcting the amount, the pictograph 26 is formed with the correct length.

However, in a medium with high recording sensitivity, when the pulse interval is short, the diffusion heat of the previous recording pulse will be affected.

The rise of the recording film becomes relatively faster, the front edge of the pit advances, and the pit 27 becomes longer by τ. Therefore, in such a case, if the detected pulse interval is large, As shown by the broken arm in FIG. 3(d), by delaying the leading edge 21b of the next pulse to be recorded in advance, the pulse 29f can be recorded with the correct length.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in accordance with the first embodiment.

FIG. 1 shows an embodiment of a source disk device capable of additional recording to which the present invention is applied, where l is an optical disk, 2 is a spindle motor, and 3 is an optical head.

This optical head consists of four components: a semiconductor laser 3a, a collimating lens 3b, and an objective lens 3c.

The recording signal 4S is input from the input terminal 4 and is input to the decoder 8 and the first delay circuit 5. The decoder 8 detects pulse intervals, and when a pulse interval longer than a predetermined length is detected, f
ζ, sends a trigger signal 8S to the pulse generation circuit 9. When the pulse generation circuit 9 receives the trigger signal 8S, it generates a gate pulse 9s of a constant length.

Further, the recording signal delayed by τ in the first delay circuit 5 is input to the second delay circuit 6 and an AND gate (1), and the AND gate 1o outputs a correction pulse (1) 8.

1 delayed by r by the second delay circuit 6Iζ
The g number 6S and the correction pulse los are connected to the OR gate 7.
A signal 7S is obtained by manually correcting the recording pulse using the OR gate 7. This signal 7S is the laser drive circuit 11
is input to change the emission power of the semicircular laser 3a.

This intensity-modulated laser light is irradiated onto the optical disc l, and information is recorded on the optical disc l.

As a recording medium, a thin film of Se chalcogenide is used as PM.
A material deposited on an MA substrate is used. This recording medium is amorphous before recording, but when it is irradiated with laser light, the temperature of that part increases and crystallizes when it exceeds a certain threshold. As a result, the reflectance becomes high and the recording becomes in focus.

FIG. 4 shows a concrete circuit example of the decoder 80).

8a is a shift register, 8b is an inverter group, 8c is A
ND gate is shown. The trigger signal 8S is output from the decoder 8 when the L-level pulse width of the recording signal 4S input to the soft register 8a becomes equal to a predetermined width, that is, the pulse width determined by the number of inverter groups 8b. This embodiment performs recording correction for the case shown in FIG. 3(b) where the sensitivity of the recording film is low! , when the interval between the immediately preceding pulses is wide, the previous edge is advanced to lengthen the next recording pulse.O Below, the operation of this embodiment will be explained with reference to FIG.

When record 1g' No. 4S is input, the decoder 8.

The L level pulse intervals P1 and P2 of the recording signal 48 (see FIG. 5(a)) are detected, and the detection signal 8S is output only when one interval is longer than P2. The pulse generation circuit 9 uses the detection signal 8S as a trigger to generate a gate pulse 9S of a certain length.
Output. The width of the gate pulse 9S is larger than the sum of the delay times τ1 and τ2. This gate signal 9S and the signal 5S, which is obtained by delaying the recording signal 4S by τ1, are input to an AND gate (1), which generates a correction pulse. (1) 8 is obtained.The delayed arc time τ1 is a value larger than the operation delay of the decoder 8.

The correction pulse and the signal 6S delayed by τ1+τ2 from the recording signal 4S by the second delay circuit 6 are output to the OR gate 7.
is input. The delayed signal 6S is a correction pulse (
1) Recording pulse 4b with a long previous pulse interval due to 8
However, the front edge is corrected to be 72 minutes longer.

As described above, in this embodiment, it is possible to correct in advance errors in recording bits due to differences in pulse intervals and form pits of correct length.

Next, a second embodiment of the present invention is shown in FIG. 6, and its operation will be explained with reference to FIG. In this embodiment, as in the first embodiment, correction recording is performed for the recording film shown in FIG. 3(b) where the sensitivity is low. In this embodiment, first, when the L level pulse interval immediately before the recording pulse is short, that is,
In the case of Pl in FIG. 7(a), the relative error is corrected by delaying the front edge of the recording pulse, and then the width of all recording pulses is widened by the same amount to finally obtain the correct recording pulse. It was designed to obtain

The decoder 8 of this embodiment has a short interval P1 of the recording signal 4S.
is detected and outputs a trigger signal 8S.

The pulse generating circuit 9 is triggered by this trigger signal 8S, and its output is inverted by the inverter 35 and output from the seventh pulse generating circuit 9.
The signal waveform 35.3 shown in Figure (c) is obtained. This gate signal 358 and the signal 6S obtained by delaying the recording signal 4S by τ1+τ2 are input to the OR gate 31, and from the OR gate 31 the correction pulse 31 shown in FIG.
8 is obtained. Here, τ1 is the time for correcting the delay of the decoder 8, and τ2 is the recording correction time.

Next, this correction pulse 31S and the recording signal 4S are set to τl.
A N D gate 32 is the AND of the signal 5S delayed by
By taking this, a 1 number 328 is obtained in which the previous edge of the next recording pulse with a short pulse interval p1 is deleted by 2.

Further, this signal 32S and the signal 32S are transferred to a delay circuit 33.
When inputting the signal 338 extended by τ2G to the OR gate 34 and widening the pulse width of all recording pulses by τ2, the leading edge becomes relatively τ when the pulse interval P2 is wide.
A corrected recording signal 348 advanced by two is obtained.

By using this front lens recording signal 348, 2 can be corrected in advance based on the time difference required for temperature rise, and recording can be performed with the correct pit length.

The first point mentioned above. The second embodiment is a third embodiment in which the sensitivity of the recording film is low.
This is the correction method for the case in Figure (b), but in the case of Figure 3 (d), which has high sensitivity, when the pulse interval is short, the temperature rises faster due to the effect of conductive heat from the previous pulse, so It is sufficient to delay the leading edge of the pulse.

Such correction recording is realized by using the output of the AND gate 32 of the second embodiment shown in the sixth factor as a recording signal. That is, in the second implementation.

As shown in Figure 7(g), when the interval between the immediately preceding pulses is short, a signal is obtained in which the leading edge of the primary recording pulse is shaved off by τ2, so this can be used as it is as the first recording signal. .

A third embodiment of the present invention is shown in FIG.

The operation will be explained using FIG. 9.

This example uses 2P1+P2 . between three different pulses. P
3, the correction amount is adaptively changed by 5 times, and no correction is applied when the pulse interval is short Pl.

In the case of P3, which has a slightly wider interval, a correction is made to advance the cutting edge of the i next recording pulse by τ3, and then P3, which has the widest pulse interval, is added.
In the case of 2, the correction amount is further increased by f by τ2, and τ2+ is set to 3.

According to this embodiment, even when there are three or more types of signal inversion intervals using the AP modulation method, it is possible to always record with the optimum length of bits.

The operation of this embodiment will be explained using FIG. 8 and FIG. 9.

When an input signal 4S having a waveform as shown in FIG. 9(a) is input to the input terminal 4, the second decoder 54 outputs @
AiJ pulse with a pulse width of P3 is detected and the second pulse generation circuit 55 is triggered. Therefore, the second pulse generation circuit 55 outputs a signal with the waveform shown in FIG. 9(b). 558 is output.

The first decoder 52 detects the immediately preceding pulse with a pulse width of P2 and outputs a trigger pulse, so the first pulse generating circuit 53 detects the waveform 538 of the waveform shown in FIG. Output.

The 1g No. 558 and the (τ1+τ2)4 extended recording signal are input to an AND gate 57, and the AND gate 5
7, the waveform signal shown in the same figure (d) "j" 57
S is output. On the other hand, record No. 48 delayed by 1 with the signal 538 is input to the AND gate 56, and the
The ND gate 56 outputs a signal 56S shown in FIG.

Next, the nJ multiplication signal 573568. and (t1+τ
2+τ3) The delayed recording signal sts is sent to the OR gate 58
When the immediately preceding pulse interval is Pl, no correction is applied to the signal 58s shown in FIG. and at P2, set the front edge of the recording pulse to (
τ2+τ3) An advanced recording signal is obtained.

Next, when the recording pit length becomes as short as the laser beam spot diameter, the laser disappears before the recording film is sufficiently heated, and the pits may not be formed sufficiently.Such a case In this case, it is possible to record with the correct pit length by widening the recording pulse width in advance.

The fourth embodiment 9 of the present invention shown in FIG. L of
When the pulse width of the level is long, the leading edge of the recording pulse is advanced by .tau.2, as in the previous embodiments.

The operation of this embodiment will be explained with reference to the waveform diagram of FIG. 11.

When the record 1g 4S of the waveform shown in il1 figure (a) is input to the input terminal 4, the decoder 8 detects the L level pulse width P2 and converts the trigger signal into the first pulse generation. Output to circuit 9. The pulse generating circuit 9 is triggered by the trigger signal l and outputs a signal 9S having the waveform shown in FIG.

On the other hand, the decoder 72 detects a recording pulse having a pulse width of P4, and upon detecting this, outputs a trigger signal g to the third pulse generating circuit 73. This triggers the pulse generating circuit 73 and outputs the epitome-shaped signal 738 shown in FIG. 3(C).

The recording signal delayed by τl and the signal 9S are input to the AND gate (1), and the AND gate (1)
A signal (1) 8 shown in FIG. On the other hand, from AND gate 74.

[2+τ3 at τ1+] Delayed signal 8 and signal 7
38 is input from the AND gate 74 as shown in FIG.
A signal 748 with a waveform shown in is outputted as a recording signal 68 delayed by (τl+r2). Said signal! O
8 and signal 748 are input to OR gate 58, which outputs
From the R gate 58, a signal 58S having the waveform shown in FIG. After 4 recording pulses (with a recording pulse length of P4) are emitted, a signal 588 is obtained in which the edge is delayed by τ4 and the pulse width is widened.

In the explanation of each of the above embodiments, the self-recording correction method was explained for cases in which the sensitivity of the recording film is high and low for write-once optical disk devices, particularly those that record information by the constant reflection of the medium. However, the error in the length of the formed pits is affected not only by the sensitivity of the recording film but also by the power of the recording laser and the thermal diffusion characteristics of the disk.

The present invention is capable of correcting vertical and vertical recording in such cases as well, as in the case of @ recording.

In addition, when the bit interval is long (this method advances the leading edge of the recording pulse) and when the focus interval is short (d), the method of delaying the leading edge of the recording pulse can be used independently.Furthermore, depending on the medium, By combining both, more accurate recording is possible, and this invention is also effective for hole-punched recording media and erasable recording media, which are Ike's heat mode recording media.

〔Effect of the invention〕

As described in detail above, according to the present invention, it is possible to compensate in advance for fluctuations in bit length due to conductive heat of recording pulses, so it is possible to always record with pits of the correct length.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a principle diagram of a conventional optical information recording/reproducing device. Figure 3 is a diagram showing the relationship between the recording signal, the temperature distribution of the recording film, and the formed bits, Figure 4 is a circuit diagram showing a specific example of a decoder, and Section 5 shows the main parts of Figure 1. FIG. 6 is a block diagram of the second embodiment, and FIG. 7 is a time chart of the signals.
The figure shows the time chart of the main parts of the signal, and Figure 8 shows the 3rd signal.
Fig. 9 is a time chart of No. 18 of its main part, Fig. (1) is a block diagram of the fourth implementation column, and Fig. 11 is a time chart of signals of its main part. 0 1... Optical disk, 2... Spindle motor, 3...
...Optical head, 3a... Semiconductor laser, 4... Input terminal, 5... Current booster circuit A, 6... Delay circuit B,
7...OR gate, 8...decoder, (1)...
A N D gate. 11...Laser drive circuit agent Patent attorney

Claims (6)

[Claims] (1) In an optical information recording method in which information is recorded and reproduced on an optical information recording medium using a focused laser beam, etc., and the information is recorded by modulating the pulse width of the recording signal, the recording pulse interval is and a means for shortening and expanding the width of the recording pulse, the width of the recording pulse being changed according to the interval from the immediately preceding pulse. method. (2) When the interval with the immediately preceding pulse is equal to or greater than a predetermined width, the leading edge of the recording pulse is relatively advanced to extend the width of the recording pulse. A recording method for optical information according to scope 1. (3) When the interval with the immediately preceding pulse is less than a predetermined width, the leading edge of the recording pulse is relatively delayed to shorten the width of the recording pulse. The optical information recording method according to item 1. (4) Three different widths P1 and P with the interval from the previous pulse
2. Optical information according to claim 1, characterized in that when P3 (where P1<P2<P3), the amount of correction of the width of the recording pulse is changed depending on the size of the width. recording method. (5) A method for recording optical information according to claim 1, characterized in that when the recording pulse width is approximately the same as the spot diameter of the laser beam, the recording pulse width is extended. . (6) The means for shortening or expanding the width of the recording pulse includes:
a means for delaying a recording signal including the recording pulse; a pulse generating means for outputting a pulse of a predetermined width in response to a trigger pulse output from the means for detecting an interval between the recording pulses; and an output from the delay means and the pulse generating means. 2. The optical information recording system according to claim 1, further comprising means for logically performing a logical operation on the pulses generated.