JP2002288837A - Information recording system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that a mark of a prescribed length cannot be recorded precisely and that it is necessary to make a light source driving part to be at a high speed when a high speed recording is performed. SOLUTION: In recording recording data having a mark length which is a multiple of a recording channel clock period T, each time when a mark length of the recording data is increased by double with respect to the recording channel clock period T, one pair of a rear part heating pulse and a rear part cooling pulse are added.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording system for recording information on a recording medium having a recording layer which reversibly changes between a crystalline phase and an amorphous phase by light from a light source.

[0002]

2. Description of the Related Art With the spread of multimedia, music C
Read-only media (recording media) such as D and CD-ROM
And information reproducing devices have been put to practical use. In recent years, phase-change media as well as write-once optical disks using dye media and rewritable MO disks using magneto-optical (MO) media have attracted attention. This phase change type medium records information by reversibly changing a recording material into a crystalline phase and an amorphous phase. Also, unlike the MO media, the phase change type media does not require an external magnetic field and can record and reproduce information only by laser light from a light source composed of a semiconductor laser, and records and erases information once by laser light. Overwrite recording is performed. Here, the semiconductor laser is driven by a semiconductor laser drive circuit.

[0003] As a general recording waveform for recording information on a phase change type medium, as shown in FIG.
(Eight Fourteen Modulatio
n) There is a single-pulse semiconductor laser emission waveform generated based on a modulation code or the like. In this recording waveform, the recording mark of the phase-change type medium is distorted due to accumulated heat, or the cooling rate is insufficient. As a result, there is a problem that the formation of an amorphous phase becomes insufficient and a recording mark having a low reflectance with respect to a laser beam cannot be obtained.

Therefore, a conventional information recording system for recording information on a phase change type medium uses a multi-pulse laser beam using a multi-stage recording power generated based on an EFM modulation code or the like as shown in FIG. The above problem is prevented by forming a mark on the phase change medium. The mark portion of the multi-pulse waveform includes a head heating pulse A for sufficiently preheating the recording film of the phase change medium to a temperature equal to or higher than the melting point temperature, a plurality of subsequent heating pulses B, and a continuous heating pulse B between these. It consists of a continuous cooling pulse C. If the emission power of the top heating pulse A is PWA, the emission power of the heating pulse B is PWB, the emission power of the cooling pulse C is PWC, and the read power is PR, PWB ≧ PWA
> PWC ≒ PR.

[0005] The erase portion of the multi-pulse waveform is composed of an erase pulse D, and its emission power PED is PWA <P
ED <PWC is set. By making the recording waveform a multi-pulse waveform in this manner, in the phase change type medium, an amorphous phase is formed as a mark portion under heating-to-cooling rapid cooling conditions, and a crystal phase is formed as a space portion under heating-only cooling conditions. In addition, a sufficient difference in reflectance between the amorphous phase and the crystalline phase can be obtained.

As information recording methods, a mark position (PPM) recording method and a mark edge (PWM: Pu)
There is an Width Recording (lse Width Modulation) recording method. Recently, a mark edge recording method capable of coping with high density has been used. When information is recorded on the phase change medium by the mark edge recording method, the period T based on the recording channel clock is 0.5
A heating pulse and a cooling pulse having a pulse width of T were used.

That is, a multi-pulse light obtained by adding a set of a heating pulse and a cooling pulse each time the mark length of recording data increases by 1T is used. FIG. 9 shows a typical recording waveform. In this recording waveform, recording data having different mark lengths can always be recorded under constant heating / cooling conditions, so that the edge shift depending on the mark length of the recording data is reduced. When high-speed recording is performed using this recording waveform, the recording channel clock is doubled, and the recording waveform is doubled.
The frequency is increased at the same magnification as the recording linear velocity such as twice.

Japanese Patent Application Laid-Open No. 62-11412 discloses an optical information recording apparatus in which the rise or fall of a recording signal is delayed by a predetermined time to cancel a change in the duty ratio of a detection signal during reproduction. Have been.
Japanese Patent Application Laid-Open No. 5-32811 discloses that when data is recorded on a phase change optical disk, the power level of the laser beam is changed from the crystallization power of the recording film of the phase change optical disk to the recording power at which the recording film melts. An optical recording method of information is described which, after being raised, is instantaneously reduced to a power level lower than the crystallization power.

[0009]

When information is recorded on a phase change type medium by a mark edge recording method, the phase change type medium performs sufficient heating and quenching at a portion where a recording mark is formed to remove edges before and after the mark. It is important to form sharply. However, when performing high-speed recording, the recording waveform is kept as it is, and the recording channel clock is increased in frequency to the same magnification as the recording linear velocity, such as twice or four times, so that the width of the heating pulse and the cooling pulse is very small. Therefore, it has been difficult to obtain the ultimate temperature and the cooling rate required for changing the layer of the recording film. For this reason, the formation of the mark became insufficient, and a mark having an accurate mark length could not be obtained.

In high-speed recording, if the rise time and fall time of the semiconductor laser drive circuit are longer than the recording channel clock, for example, when a 9T mark is recorded, as shown in FIG. Since the recording waveform is distorted, the phase change medium cannot be sufficiently heated and cooled, resulting in a problem that the recording mark is shortened. As shown in FIG. 10B, the RF signal (eye pattern) as a reproduced signal obtained at this time has an extremely short mark length as the recording data length increases. Therefore, during high-speed recording,
A high-speed response of the semiconductor laser driving circuit is required, and the circuit becomes large-scale and the cost is increased.

According to the present invention, an information recording system capable of securing a sufficient heating time and cooling time, obtaining a predetermined recording mark length without increasing the speed of a light source driving unit, and performing high-speed recording. The purpose is to provide.

[0012]

In order to achieve the above object, the present invention is directed to a light source for recording information as a mark on a recording medium having a recording layer reversibly changing between a crystalline phase and an amorphous phase. When recording with light from, the light source emits multi-pulse light to form a recording mark, the multi-pulse light is a head heating pulse,
In the information recording method comprising a rear cooling pulse and a rear heating pulse, which are alternately inserted between the last heating pulse and the last cooling pulse according to the length of the mark to be recorded, and the last cooling pulse, When recording the recording data having a mark length that is an integral multiple of the recording channel clock cycle T, the rear heating pulse and the rear cooling pulse each time the mark length of the recording data increases twice the recording channel clock cycle T. This is to increase one set of pulses.

According to a second aspect of the present invention, in the information recording method of the first aspect, each time the data length of the recording mark is doubled with respect to the recording channel clock cycle T, the rear heating pulse and the rear heating pulse are increased. When increasing the number of cooling pulses by one set, the total of the pulse widths of the rear heating pulse and the rear cooling pulse is doubled with respect to the recording channel clock period T.

According to a third aspect of the present invention, there is provided the information recording system according to the first aspect, wherein the shortest mark length is included in the recording data of each mark length.
When recording a plurality of recording data having different mark lengths by T, the total of the pulse widths of the increased set of the rear heating pulse and the rear cooling pulse is doubled with respect to the recording channel clock cycle T. Things.

[0015]

FIG. 1 shows a part of an example of an information recording / reproducing apparatus to which the present invention is applied, and FIG. 2 shows a timing chart thereof. This information recording / reproducing apparatus is an example of an information recording / reproducing apparatus that records (overwrites) CD-ROM format code data on a phase-change medium of a phase-change optical disc, and uses a mark edge (PWM) using an EFM modulation code. ) Make a record.

In this information recording / reproducing apparatus, at the time of recording, EF is controlled by a light intensity control means comprising a digital circuit (not shown).
A pulse control signal is generated based on the M data, and a semiconductor laser driving circuit drives a light source composed of a semiconductor laser LD of an optical head with a driving current corresponding to the pulse control signal to generate a multi-pulse light as shown in FIG. The phase change type optical disk is rotated by a spindle motor, and the optical head irradiates the multi-pulse light from the semiconductor laser LD to the phase change type optical medium of the phase change optical disk via the optical system. Information is recorded by forming a recording mark on the mold medium.

In this information recording / reproducing apparatus, at the time of reproduction, the semiconductor laser LD is driven by a semiconductor laser drive circuit to emit light at a reproduction power (read power), and the optical head reproduces light of the reproduction power from the semiconductor laser LD. Is irradiated on a phase change type medium through an optical system, and the reflected light is photoelectrically converted by a light receiving unit through the optical system to obtain a reproduction signal. The multi-pulse light emitted from the semiconductor laser LD at the time of recording is a multi-pulse light composed of a head heating pulse A, a plurality of subsequent rear heating pulses B, and a continuous rear cooling pulse C therebetween. It is. However, the emission power of the first heating pulse A and the emission power of the rear heating pulse B are the same.

The semiconductor laser LD of the optical head is constituted by a semiconductor laser drive circuit as shown in FIG.
To the emission power of the first heating pulse A, the rear heating pulse B
Is supplied, and a constant current source 1 is supplied.
2 supplies a constant current corresponding to the light emission power of the cooling pulse C, and a constant current source 13 supplies a constant current corresponding to the light emission power of the erase pulse D.

The light intensity control means (not shown) generates an A + B pulse control signal, a C pulse control signal, and a D pulse control signal based on the EFM data.
16 turn on / off the constant current sources 11 to 13 by the A + B pulse control signal, the C pulse control signal and the D pulse control signal from the light intensity control means, respectively. To emit light.

This information recording / reproducing apparatus records recording data on a phase-change type medium with a recording waveform as shown in FIG. 2 so that an accurate mark length can be obtained even at a high recording speed even when the recording channel clock has a high frequency. Things. The multi-pulse light emitted from the semiconductor laser LD has a pulse width of the first heating pulse A when a mark of 3T (T is the cycle of a recording channel clock), which is the shortest mark length, is recorded as shown in FIG. 1.5T, tail cooling pulse C
r has a pulse width of 1T, and has another odd length (5T, 7T, 9T, 1T) with respect to the period T of the recording channel clock.
1T), a mark having a length of 1T) is recorded between the first heating pulse A and the last cooling pulse Cr.
The cooling pulse C having a pulse width of T and the heating pulse B having a pulse width of 1T are set so as to be continuous by predetermined pairs different from each other. Therefore, the cumulative length of the recording waveform is n-0.5T.

When a mark having another even length (4T, 6T, 8T, 10T) with respect to the recording channel clock cycle T is recorded, a mark having an odd length is recorded. The recording waveform is set according to a different rule. When recording a mark having a length of 4T or 8T, the pulse width of the heating pulse B located at the center of the subsequent portion excluding the head heating pulse A is set to 0.5.
T, the pulse width of the cooling pulse C before and after the heating pulse B is set to 0.75T, and the pulse width of the other heating pulse B and the cooling pulse C is set to 1T.

When a mark having a length of 6T or 10T is to be recorded, the pulse width of the cooling pulse C located at the center of the subsequent portion excluding the head heating pulse A is set to 0.5T,
The pulse width of the heating pulse B before and after the cooling pulse C is set to 0.75T, and the pulse widths of the other heating pulses B and the cooling pulse C are set to 1T. By setting the recording waveform in this manner, as shown in FIG. 3A, the emission waveform of the semiconductor laser LD has a sufficiently large width of the heating pulse and the cooling pulse corresponding to the edge portions before and after the mark, and the reproduction is performed. Signal jitter can be suppressed.

The cumulative length of the heating pulse and the cooling pulse is the same for a mark having an odd length and a mark having an even length for the recording channel clock period T (n: integer). −0.5T, which means that there is no edge shift between the marks having odd lengths and the marks having even lengths, and all mark lengths are integral multiples of 1T. In addition, the mark median value of a mark having an even length has a pulse width of 0.5T, and the mark formation is not sufficient. However, in the PWM recording, even if the mark is thin, the reproduction signal is not affected.

The light intensity control means composed of a digital circuit is E
Since a pulse control signal is generated based on the FM data and the semiconductor laser driving circuit drives the semiconductor laser LD with a drive current corresponding to the pulse control signal, the multi-pulse light is emitted as described above. The control means has a simple circuit configuration, and the semiconductor laser drive circuit can be easily configured with a low-cost circuit. Further, as shown in FIG. 2, the light intensity control means composed of a digital circuit may use a synchronous circuit which generates a pulse control signal based on EFM data in synchronization with a recording channel clock and a clock having a frequency twice as high as that of the recording channel clock. And a very accurate pulse width can be obtained.

With this information recording / reproducing apparatus, a mark recorded on a phase change type medium can be formed into an accurate mark equal to the EFM data length. As shown in FIG. (Eye pattern) is as good as when low-speed recording is performed.

The set values such as the pulse width of the first heating pulse A and the pulse width of the last cooling pulse Cr are representative values, and are actually optimized according to the recording material and the media phase configuration. You just have to adapt the value. In addition, since the cumulative length of the recording waveform and the length of the formed mark differ depending on the recording modulation method, the recording density, and the diameter of the light spot formed by the laser beam on the medium, the length of the recording channel clock is even. The setting of the recording waveform may be exchanged between the recording data having a length of the recording data and the recording data having an odd length.

As described above, this information recording / reproducing apparatus is an example of the information recording / reproducing apparatus to which the invention of claim 1 is applied, and has a recording layer which reversibly changes between a crystalline phase and an amorphous phase. When information is recorded on a recording medium by light from a semiconductor laser LD as a light source, the light source LD
In the information recording method of forming a recording mark by emitting a multi-pulse light composed of a head heating pulse A, a plurality of subsequent rear heating pulses B, a rear cooling pulse C, and a rear cooling pulse Cr, the recording channel clock is used. Since the pulse width of the rear heating pulse B and the rear cooling pulse C is set to be substantially the same as the recording channel clock period when recording data having an even or odd mark length with respect to the cycle T, sufficient heating can be performed. Time and cooling time can be secured, a predetermined recording mark length can be accurately obtained without increasing the speed of a semiconductor laser driving circuit as a light source driving unit, and high-speed recording can be performed.

This information recording / reproducing apparatus is characterized in that
An example of an information recording and reproducing apparatus to which the described invention is applied,
When recording the recording data of the other mark length with respect to any one of the even length and the odd length, the rear heating pulse B, the rear cooling pulse C, and the last cooling pulse Cr
Of the rear heating pulse B so that the difference between the sum of the cooling pulse width and the sum of the heating pulse widths in the light emitting portion becomes substantially the same between the even-length recording data and the odd-length recording data with respect to the recording channel clock cycle T. Since the width and the width of the rear cooling pulse C are set, both the even-length recording data and the odd-length recording data do not undergo an edge shift and do not increase the speed of the semiconductor laser driving circuit as the light source driving unit. Can be accurately obtained, and high-speed recording can be performed.

This information recording / reproducing apparatus is characterized in that
An example of an information recording and reproducing apparatus to which the described invention is applied,
A heating pulse, a cooling pulse, and a heating pulse located at the center of the light emitting portion of the rear heating pulse and the rear cooling pulse when recording data of the other mark length for one of the even length and the odd length mark length is recorded. 0.75 pulse or cooling pulse, heating pulse and cooling pulse width
Since T, 0.5T, and 0.75T, the pulse widths of the heating pulse and the cooling pulse corresponding to the edge portions before and after the mark can be made sufficiently large to form a sharp edge portion, and the reproduced signal jitter can be formed. Can be suppressed.

FIG. 4 shows an operation timing of an example of the information recording / reproducing apparatus to which the inventions of claims 1, 2 and 4 are applied.
This information recording / reproducing apparatus performs recording by configuring a multi-pulse emission waveform so that an accurate mark length can be obtained. Basically, the information recording / reproducing apparatus to which the invention according to claims 1 to 3 is applied. It is the same as the example of the apparatus, but the following points are different from the example of the information recording / reproducing apparatus to which the inventions of claims 1 to 3 are applied.

In this information recording / reproducing apparatus, the emission waveform of the multi-pulse has an odd length (3T, 5T, 7T, 9) with respect to the period T of the recording channel clock as shown in FIG.
When recording a mark having a length of (T, 11T), the waveform is set to be the same as that of the information recording / reproducing apparatus to which the inventions of the first to third aspects are applied. Therefore,
The cumulative length of the recording waveform is n-0.5T. That is, the light intensity control means generates an A + B pulse control signal, a C pulse control signal, and a D pulse control signal based on the EFM data, and sends the A + B pulse control signal, the C pulse control signal D, By turning on / off the constant current sources 11 to 13 by the pulse control signal, the semiconductor laser LD emits light in multi-pulses as shown in FIG.

When recording a mark having another even length (4T, 6T, 8T, 10T) with respect to the period T of the recording channel clock, a mark having an odd length is recorded. The recording waveform is set according to a different rule. When a mark having a length of 4T is recorded, a cooling pulse C + a heating pulse B + a cooling pulse C is generated during 2T, so that the recording waveform has information recording / reproducing to which the invention according to the above-mentioned claims 1 to 3 is applied. The recording waveform is set to be the same as the example of the apparatus.

When recording a mark having a length of 6T or 10T, the pulse width of the heating pulse B located at the center of the subsequent portion excluding the head heating pulse A is set to 1.5T,
The pulse width of the cooling pulse C before and after the heating pulse B is 1.25T, and the pulse width of the other heating pulse B and the cooling pulse C is 1T. When recording a mark having a length of 8T, the pulse width of the cooling pulse C located at the center of the subsequent portion excluding the head heating pulse A is set to 1.
5T, the pulse width of the heating pulse B before and after the cooling pulse C is 1.25T, and the pulse width of the other heating pulse B and the cooling pulse C is 1T.

As described above, by setting the recording waveform,
In the emission waveform of the semiconductor laser LD, the pulse width of the heating pulse and the cooling pulse corresponding to the edge portions before and after the mark is sufficiently large so that the edge of the mark is sharply formed, and the jitter of the reproduction signal can be suppressed. it can. Also,
The cumulative length of the heating pulse and the cooling pulse is the same n-0.5T for the mark having the odd length and the mark having the even length, and the mark having the odd length and the even length have the same length. There is no edge shift between the mark having the length and all mark lengths are integral multiples of 1T.
In addition, the mark median of a mark having an even length has a pulse width of 1.25 T or more, and the phase change type medium is sufficiently heated and cooled so that the mark does not become thin. Therefore, the mark has an ideal shape as compared with the example of the information recording / reproducing apparatus to which the inventions of claims 1 to 3 are applied.

The set values such as the pulse width of the first heating pulse A and the pulse width of the last cooling pulse Cr show typical values, and are actually optimized according to the recording material and the media phase configuration. You just have to adapt the value. In addition, since the cumulative length of the recording waveform and the length of the formed mark differ depending on the recording modulation method, the recording density, and the diameter of the light spot formed by the laser beam on the medium, even-length recording data and odd-length recording data are used. The setting of the recording waveform may be exchanged between.

As described above, this information recording / reproducing apparatus is an information recording / reproducing apparatus to which the inventions of claims 1 and 2 are applied in the same manner as the example of the information recording / reproducing apparatus to which the inventions of claims 1 to 3 are applied. And the same effect can be obtained.

This information recording / reproducing apparatus is characterized in that:
An example of an information recording and reproducing apparatus to which the described invention is applied,
When recording data of the other mark length with respect to any one of the even length and the odd length, a rear heating pulse A, a rear cooling pulse C, and a rear cooling pulse Cr are used.
The pulse widths of the heating pulse B, the cooling pulse C and the heating pulse B or the cooling pulse C and the heating pulse B and the cooling pulse C which are located at the center of the light-emitting portion are 1.25T and 1.5T.
And 1.25T, the heating pulse width and the cooling pulse width are sufficient at the center of the mark, and the mark does not become thin. Therefore, it is possible to further suppress the jitter of the reproduction signal.

FIG. 5 shows an operation timing of an example of an information recording / reproducing apparatus to which the invention of claim 5 is applied. This information recording / reproducing device is basically the same as the example of the information recording / reproducing device to which the inventions of claims 1 to 3 are applied, but the following points are obtained by applying the inventions of claims 1 to 3. This is different from the example of the information recording / reproducing apparatus described above.

In the information recording / reproducing apparatus to which the inventions according to the first to third aspects of the present invention are applied, a recording pulse having an even length and a recording mark having an odd length have a heating pulse width in a recording waveform. And the regularity of the cooling pulse width is different, causing a slight shift in the heating and cooling conditions, and an edge shift occurs in a recording mark having an even length when compared to a recording mark having an odd length. I do. Since the detection window width Tw of the reproduction signal decreases as the recording density increases, an error occurs in the data due to the edge shift.

Therefore, in the information recording / reproducing apparatus, the multi-pulse emission waveform is corrected so as to prevent such an edge shift from occurring and reduce errors. The recording waveforms for the odd-length and even-length recording marks are the same as in the example of the information recording / reproducing apparatus to which the inventions of claims 1 to 3 are applied. In the recording waveform for the odd-length recording mark, the pulse widths of the heating pulse and the cooling pulse other than the head heating pulse A are all 1T, and 3T, 5T, 7
No edge shift occurs between the marks T, 9T, and 11T.

Therefore, in this information recording / reproducing apparatus,
The following correction is performed by the light intensity control means comprising a digital circuit for the recording waveform for the recording mark of an even length having an irregular mark length. First, the recording waveform for a recording mark having a length of 4T or 8T is such that the pulse width of the heating pulse B located at the center of the subsequent portion excluding the head heating pulse A is 0.5T, and the pulse width is not sufficient for high-speed recording. Since there is no such mark, an edge shift occurs that becomes shorter for an odd-length recording mark.

Therefore, in this information recording / reproducing apparatus, 4
When recording a mark having a length of T or 8T, a heating pulse B located at the center of the subsequent portion excluding the first heating pulse A as shown in FIG. Is corrected so as to increase by the time α4, α8 equivalent to the edge shift amount, and 0.5T + α4, 0.5T + α8 is set as the heating pulse B located at the center of the subsequent portion excluding the head heating pulse A.
, And a cooling pulse C having a pulse width of 0.75 T before and after the heating pulse B is generated.

The recording waveform for a recording mark having a length of 6T or 10T is such that the pulse width of the cooling pulse C located at the center of the subsequent portion excluding the head heating pulse A is 0.
Since the pulse width is not sufficient at the time of high-speed recording at 5T, an edge shift occurs in which the trailing edge becomes shorter for a recording mark having an odd length.

Therefore, in this information recording / reproducing apparatus, 6
When recording a mark having a length of T, 10T,
The pulse width of the cooling pulse C located at the center of the subsequent portion excluding the head heating pulse A by the light intensity control means composed of a digital circuit is set to a time α6 equivalent to the edge shift amount.
The correction is made so as to increase by α10, and the cooling pulse C located at the center of the subsequent portion excluding the head heating pulse A
Are generated with pulse widths of 0.5T + α6 and 0.5T + α10, and heating pulses B before and after the cooling pulse C are generated with a pulse width of 0.75T.

By performing such a correction, the edge shift between the mark having the odd-numbered length and the mark having the even-length length is completely corrected, and higher-density recording becomes possible. Further, as described above, the heating pulse B and the cooling pulse C located at the center of the subsequent portion excluding the head heating pulse A
Are corrected so as to increase both the pulse widths of the recording marks, the thinning of the central portion of the recording mark can also be improved, and a better reproduction signal can be obtained.

It should be noted that the set values of the recording waveform are representative values, and in practice, a value optimized according to the recording material, media phase configuration and the like may be applied. In addition, since the cumulative length of the recording waveform and the length of the formed mark differ depending on the recording modulation method, the recording density, and the diameter of the light spot formed by the laser beam on the medium, even-length recording data and odd-length recording data are used. The setting of the recording waveform may be exchanged between.

Since the length of the recording mark to be formed depends on the cumulative length of the heating pulse and the cooling pulse, the effect similar to the above can be obtained by correcting the edge shift amount with respect to the cumulative length. . Therefore, the heating pulse and the cooling pulse to be corrected may be other than those located at the center of the succeeding portion excluding the first heating pulse A. For example, the edge shift amount may be corrected for the pulse width of the last cooling pulse Cr. It may be. Further, in the light intensity control means composed of a digital circuit, the means for accurately generating the corrected heating pulse and the cooling pulse in multiple stages can be easily constituted by a delay circuit such as a multi-tap delay line or a plurality of mono-multi vibrators. Can be.

As described above, in this information recording / reproducing apparatus,
An example of an information recording / reproducing apparatus to which the invention according to claim 5 is applied, wherein when recording data having the length of one of the mark lengths of one of the even-numbered length and the odd-numbered length is recorded, Since the heating pulse or the cooling pulse of any one of the light emitting portions of the heating pulse B, the rear cooling pulse C, and the last cooling pulse Cr has been corrected, recording data having an even length and recording data having an odd length. It is possible to completely correct a slight edge shift due to the difference in the heating and cooling conditions of the medium. The invention described in claim 5 can be similarly applied to an example of an information recording / reproducing apparatus to which the inventions described in claims 1, 2, and 4 are applied.

Next, an example of an information recording / reproducing apparatus to which the invention according to claim 6 is applied will be described. Ge-Sb is used as a recording layer of a phase-change medium conventionally used.
-Te system, Ge-Te-Sb-S system, Te-Ge-Sn
-Au, Ge-Te-Sn, Sb-Se, Sb-
Se-Te system, Sn-Se-Te system, Ga-Se-Te
System, Ga-Se-Te-Ge system, In-Se system, In-
There are Se-Te system, Ag-In-Sb-Te system and the like.

Each example of the information recording / reproducing apparatus to which the invention of claim 6 is applied is an example of the information recording / reproducing apparatus to which the invention of claims 1 to 3 is applied, or the examples of the information recording / reproducing apparatus according to claims 1, 2 and 4. In the example of the information recording / reproducing apparatus to which the invention of claim 5 is applied, and in the example of the information recording / reproducing apparatus to which the invention of claim 5 is applied, Ag-In-Sb is used as the recording layer of the phase change type medium.
-A recording material of Te type is used. When data is recorded on a phase-change medium having such a recording layer, since the amorphous phase formation is highly dependent on the quenching condition by heating → cooling, a heating pulse for forming a mark and cooling immediately thereafter are used. The formation of a mark is greatly affected by the difference in the light emission power from the pulse. Therefore, an example of an information recording / reproducing apparatus to which the inventions of claims 1 to 3 are applied, an example of an information recording / reproducing apparatus to which the inventions of claims 1, 2, and 4 are applied, and an example of the information recording / reproducing apparatus of claim 5 described above. Compared to the example of the information recording / reproducing apparatus to which the invention is applied, the mark is recorded more clearly, and the jitter of the reproduced signal can be suppressed.

The relationship between the cumulative length of the heating pulse and the cooling pulse and the formed mark length tends to almost coincide with a straight line as shown in FIG. 6, and the recording data having the even length and the odd length have the same length. The length of all marks can be easily set to an integral multiple of 1T without causing an edge shift with the recording data having a length. In addition, the accuracy of the correction can be made very high even for a slight edge shift. Note that even when another recording material is used for the recording layer, the relationship between the recording waveform and the jitter characteristic of the reproduction signal, and the relationship between the pulse width of the heating pulse and the cooling pulse and the mark length are basically the same. Therefore, it goes without saying that the present invention is effective.

As described above, in the example of the information recording / reproducing apparatus to which the invention of claim 6 is applied, the recording layer is made of AgInSbTe.
Because of the recording material of the system, the relationship between the cumulative length of the heating pulse and the cooling pulse in the recording waveform and the length of the formed mark almost coincides with a straight line, and the recording data having the even length and the odd length have the same length. It is possible to increase the accuracy of the correction even for a slight edge shift without causing an edge shift with the recording data.

[0053]

As described above, according to the first aspect of the present invention, when information is recorded on a recording medium having a recording layer which reversibly changes between a crystalline phase and an amorphous phase by light from a light source. In the information recording method of forming a recording mark by causing the light source to emit a multi-pulse light including a head heating pulse, a plurality of subsequent rear heating pulses, a rear cooling pulse, and a rear cooling pulse, the recording channel clock is used. When recording data having a mark length of any one of an even number length and an odd number length with respect to the period T, the pulse width of the rear heating pulse and the rear cooling pulse was set to be substantially the same as the recording channel clock period. Time and cooling time can be secured, and a predetermined recording mark length can be accurately obtained without increasing the speed of the light source driving unit, enabling high-speed recording. It made.

According to a second aspect of the present invention, in the information recording system according to the first aspect, when recording data of one of the even-length mark length and the odd-length mark length, the recording data of the other mark length is recorded. The difference between the sum of the cooling pulse widths and the sum of the heating pulse widths in the light emitting portions of the rear heating pulse, the rear cooling pulse, and the last cooling pulse is substantially the same between the even-length record data and the odd-length record data. Since the width of the rear heating pulse and the width of the rear cooling pulse are set at the same time, no edge shift occurs for both the recording data having the even length and the recording data having the odd length, and the light source drive is performed. A predetermined recording mark length can be accurately obtained without speeding up the section, and high-speed recording can be performed.

According to a third aspect of the present invention, in the information recording method according to the first or second aspect, the recording data of one of the even length and the odd length is recorded with respect to the other mark length. The widths of the heating pulse, cooling pulse and heating pulse or cooling pulse, heating pulse and cooling pulse located at the center of the light emitting portion of the rear heating pulse and the rear cooling pulse are 0.75T, 0.5T and 0.75T. Therefore, the pulse widths of the heating pulse and the cooling pulse corresponding to the edge portions before and after the mark can be made sufficiently large, a sharp edge portion can be formed, and the jitter of the reproduced signal can be suppressed.

According to a fourth aspect of the present invention, in the information recording method according to the first or second aspect, the recording data of the other mark length for one of the even length length and the odd length length is recorded. The width of the heating pulse, the cooling pulse and the heating pulse or the cooling pulse, the heating pulse and the cooling pulse, which are located at the center of the light emitting portion of the rear heating pulse, the rear cooling pulse and the last cooling pulse, are 1.25T, 1. Since 5T and 1.25T are used, the heating pulse width and the cooling pulse width are sufficient even at the center of the mark, and the mark does not become thin. Therefore, it is possible to further suppress the jitter of the reproduction signal.

According to the invention set forth in claim 5, claim 1 is
In the information recording method described in 2, 3, or 4, when recording data of the other mark length with respect to any one of the even length and the odd length, the rear heating pulse, the rear cooling pulse, and the last Either the heating pulse or the cooling pulse of the light emission part of the tail cooling pulse has been corrected, so that a slight edge shift due to the difference in the heating and cooling conditions of the media between the even-length recording data and the odd-length recording data is completely corrected. It becomes possible.

According to the invention set forth in claim 6, according to claim 1,
In the information recording method described in 2, 3, 4, or 5, the recording layer is made of an AgInSbTe-based recording material.
The relationship between the cumulative length of the heating pulse and the cooling pulse in the recording waveform and the formed mark length almost coincides with a straight line, and an edge shift occurs between the recording data having an even length and the recording data having an odd length. In addition, the accuracy of the correction can be made extremely high even for a slight edge shift.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a part of an example of an information recording / reproducing apparatus to which the inventions of claims 1 to 3 are applied.

FIG. 2 is a timing chart showing the operation timing of the device.

FIG. 3 is a waveform diagram for explaining the device.

FIG. 4 is a timing chart showing an operation timing of an example of an information recording / reproducing apparatus to which the inventions of claims 1, 2 and 4 are applied.

FIG. 5 is a timing chart showing an operation timing of an example of an information recording / reproducing apparatus to which the invention according to claim 5 is applied.

FIG. 6 is a characteristic diagram showing the relationship between the cumulative length of a heating pulse and a cooling pulse and the formed mark length in an example of an information recording / reproducing apparatus to which the invention of claim 6 is applied.

FIG. 7 is a diagram showing examples of recording data, recording waveforms, and recording marks in a conventional information recording method.

FIG. 8 shows recording data in another conventional information recording method;
FIG. 3 is a diagram illustrating an example of a recording waveform and a recording mark.

FIG. 9 is a waveform diagram showing a recording waveform for each recording data in the information recording method.

FIG. 10 is a diagram for explaining the information recording method.

[Explanation of symbols]

 LD Laser diode 11-13 Current source 14-16 Switching element

Claims (3)

[Claims] When recording information as a mark on a recording medium having a recording layer that reversibly changes between a crystalline phase and an amorphous phase with light from a light source, the light source emits multi-pulse light. The recording pulse is formed by multi-pulse light, the first heating pulse, the last cooling pulse, and between the first heating pulse and the last cooling pulse depending on the length of the mark to be recorded. In the information recording method including the rear cooling pulse and the rear heating pulse that are inserted alternately, when recording data having a mark length that is an integral multiple of the recording channel clock period T, the mark length of the recording data is equal to the recording channel. An information recording method, wherein the rear heating pulse and the rear cooling pulse are increased by one set every time the clock cycle T is doubled. 2. The information recording method according to claim 1, wherein each time the data length of the recording mark is doubled with respect to the recording channel clock cycle T, the rear heating pulse and the rear cooling pulse are increased by one set. In the case, the sum of the pulse width of the rear heating pulse and the rear cooling pulse,
An information recording method wherein the recording channel clock cycle T is doubled. 3. The information recording method according to claim 1, wherein a plurality of recording data including the shortest mark length among the recording data of the respective mark lengths and having a mark length different by 2T from the shortest mark length is recorded. The sum of the pulse widths of the set of the rear heating pulse and the rear cooling pulse to be increased is doubled with respect to the recording channel clock period T.