JP3508932B2 - Information recording method, optical head and information recording device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording method for recording information on a recording medium having a recording layer that reversibly changes its phase between a crystalline phase and an amorphous phase, by using light from a light source.
The present invention relates to a head and an information recording device .

[0002]

2. Description of the Related Art Music C has become popular with the spread of multimedia.
Playback-only media (recording media) such as D and CD-ROM
And information reproducing devices have been put to practical use. Recently, in addition to a write-once type optical disc using a dye medium, a rewritable MO disc using a magneto-optical (MO) medium, a phase change type medium has been attracting attention. This phase change type medium reversibly changes the recording material into a crystalline phase and an amorphous phase to record information. In addition, 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 information can be recorded and erased once by laser light. It is possible to perform overwrite recording that is performed at the same time. Here, the semiconductor laser is driven by a semiconductor laser drive circuit.

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 the modulation code, etc., but with this recording waveform, the phase-change type medium causes tears in the recording marks due to accumulated heat, and the cooling rate is insufficient. Then, the formation of the amorphous phase becomes insufficient, and there is a problem that a recording mark having a low reflectance with respect to laser light cannot be obtained.

Therefore, a conventional information recording system for recording information on a phase change type medium is a laser beam having a multi-pulse waveform using multi-stage recording power generated based on an EFM modulation code as shown in FIG. The above problems are prevented by forming marks on the phase change medium. The mark portion of the multi-pulse waveform has a head heating pulse A for preheating the recording film of the phase change medium sufficiently above the melting point temperature, a plurality of subsequent heating pulses B, and a portion between them. It is composed of continuous cooling pulses C. If the light emission power of the first heating pulse A is PWA, the light emission power of the heating pulse B is PWB, the light emission power of the cooling pulse C is PWC, and the read power is PR, PWB ≧ PWA
> PWC≈PR is set.

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 way, in the phase-change type medium, the amorphous phase is formed as the mark part under the rapid cooling condition of heating → cooling, and the crystalline phase is formed as the space part under the cooling condition of only heating. A sufficient difference in reflectance can be obtained between the amorphous phase and the crystalline phase.

Further, as an information recording method , a mark position (PPM) recording method and a mark edge (PWM: Pu)
There is an Width Width Modulation recording method , but recently, a mark edge recording method capable of coping with high density has been used. When information is recorded on the phase change type medium by the mark edge recording method, it is 0.5 with respect to the period T based on the recording channel clock.
A heating pulse and a cooling pulse with a pulse width of T were used.

That is, multi-pulse light in which one set of heating pulse and cooling pulse is added is used every time the mark length of recording data is increased by 1T. FIG. 8 shows a typical recording waveform thereof. With this recording waveform, recording data with different mark lengths can always be recorded under constant heating and cooling conditions, and therefore edge shift depending on the mark length of the recording data is reduced. When performing high-speed recording with this recording waveform, the recording waveform remains unchanged and the recording channel clock is doubled and 4 times.
The frequency is increased at the same magnification as the recording linear velocity, such as double.

Japanese Unexamined Patent Publication 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 the change in the duty ratio of a detection signal during reproduction. Has been done.
Further, in JP-A-5-32811, when data is recorded on a phase-change optical disk, the power level of laser light is changed from the crystallization power of the recording film of the phase-change optical disk to the recording power of melting the recording film. An optical recording method of information is described which, after being raised, is instantly reduced to a power level lower than the crystallization power.

[0009]

When information is recorded on a phase-change medium by the mark edge recording method, the phase-change medium is sufficiently heated and rapidly cooled at the recording mark forming portion to remove the edge portions before and after the mark. It is important to form it clearly. However, when high-speed recording is performed, the recording waveform remains unchanged and the recording channel clock is doubled and quadrupled to have the same high frequency as the recording linear velocity, so that the width of the heating pulse and the cooling pulse is very small. Therefore, it is 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 was insufficient, and a mark having an accurate mark length could not be obtained.

Further, when high-speed recording is performed, if the rise time and fall time of the semiconductor laser drive circuit become longer than the recording channel clock, for example, when recording a 9T mark, as shown in FIG. 9A. Since the recording waveform is rounded, the phase change medium cannot be sufficiently heated and cooled, and the recording mark becomes short. The RF signal (eye pattern) as a reproduction signal obtained at this time has an extremely short mark length as the recording data length increases, as shown in FIG. 9B. Therefore, at the time of high-speed recording, a high-speed response of the semiconductor laser drive circuit is required, resulting in a large scale circuit and high cost.

[0011] The present invention can obtain a predetermined recording mark length without speeding up the light source driver can be ensured a sufficient heating time and cooling time, the information recording method makes it possible to perform high-speed recording , An optical head and an information recording device are provided.

[0012]

In order to achieve the above object, the invention according to claim 1 uses a light source as a mark with information as a mark on a recording medium having a recording layer that reversibly changes between a crystalline phase and an amorphous phase. At the time of recording with the light from, the light source emits multi-pulse light to form a recording mark, and the multi-pulse light includes at least a head heating pulse and a tail cooling pulse for recording. In an information recording method consisting of a rear cooling pulse and a rear heating pulse that are alternately inserted between the head heating pulse and the tail cooling pulse in accordance with an increase in the length of a mark to be formed,
When recording record data having a mark length that is an integral multiple of the recording channel clock period T, and the mark length is an odd number
And the even number, the data length of the recording data is 2 with respect to the recording channel clock period T , respectively.
Each time the number is doubled, the number of sets each consisting of the rear heating pulse and the rear cooling pulse is increased by one .

According to a second aspect of the present invention, in the information recording method according to the first aspect, the rear heating pulse and the rear cooling are generated every time the mark length of the recording data increases by a factor of 2 with respect to the recording channel clock period T. Each one of the pulses
One when assembled a set increasing consisting, the sum of the rear heating pulse and the pulse width of the rear cooling pulse, increased 2-fold with respect to the recording channel clock period T.

According to a third aspect of the present invention, in the information recording method according to the first aspect , the shortest mark length is included in the record data of the respective mark lengths.
When recording a plurality of recording data having different mark lengths by T, the pulse widths of the one set of the rear heating pulse and the rear cooling pulse are increased according to the increase of the mark length .
Double the sum with respect to the recording channel clock period T
And According to a fourth aspect of the invention, in the optical head that generates a pulse control signal and drives a light source with a drive current according to the pulse control signal in a semiconductor laser drive circuit to emit multi-pulse light, Light is
The information recording method according to any one of claims 1 to 3 further comprises a multi-pulse generating means . A fifth aspect of the present invention includes the optical head according to the fourth aspect.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a part of an example of an information recording / reproducing apparatus to which the invention described in claims 1 to 3 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) code data of a CD-ROM format on a phase change medium of a phase change optical disk, and uses a mark edge (PWM) by using an EFM modulation code. ) Make a record.

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

Further, in the information recording / reproducing apparatus, at the time of reproduction, the semiconductor laser driving circuit drives the semiconductor laser LD to emit light with reproduction power (read power), and the optical head emits light of reproduction power from the semiconductor laser LD. Is irradiated onto the phase-change medium via an optical system, and the reflected light is photoelectrically converted by a light receiving means via the optical system to obtain a reproduction signal. The multi-pulse light emitted from the semiconductor laser LD during recording is a multi-pulse light including a head heating pulse A, a plurality of subsequent rear heating pulses B, and a continuous rear cooling pulse C therebetween. Is. However, the emission power of the front heating pulse A and the emission power of the rear heating pulse B are the same.

The semiconductor laser LD of the above optical head is a constant current source 11 as shown in FIG.
From the emission power of the first heating pulse A, the second heating pulse B
Constant current corresponding to the emission power of the constant current source 1
A constant current corresponding to the emission power of the cooling pulse C is supplied from 2, and a constant current corresponding to the emission power of the erase pulse D is supplied from the constant current source 13.

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, and the switching element 14
Reference numerals 16 to 16 respectively turn on / off the constant current sources 11 to 13 by the A + B pulse control signal and the C pulse control signal D pulse control signal from the light intensity control means, so that the semiconductor laser LD is multi-pulse as shown in FIG. To emit light.

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

When recording marks having other even lengths (4T, 6T, 8T, 10T) with respect to the period T of the recording channel clock, when recording marks having an odd length. The recording waveform is set according to a different rule from. 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 first heating pulse A is 0.5.
The pulse width of the cooling pulse C before and after the heating pulse B is 0.75T, and the pulse widths of the other heating pulse B and the cooling pulse C are 1T.

When recording a mark having a length of 6T or 10T, 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 0.75T, and the pulse widths of the other heating pulse B and the cooling pulse C are 1T. By thus setting the recording waveform, 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. It is possible to suppress signal jitter.

The cumulative length of the heating pulse and the cooling pulse is the same n (n: integer) for the mark having an odd length and the mark having an even length with respect to the recording channel clock period T. It becomes −0.5T, and all the mark lengths are integer multiples of 1T without causing edge shift between the mark having the odd length and the mark having the even length. Further, the mark median value of the mark having an even length has a pulse width of 0.5T, and the mark formation is not sufficient. However, in the PWM recording, the reproduction signal is not affected even if the mark is thin.

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 driving current according to the pulse control signal, the multi-pulse light as described above is emitted. 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 that of the recording channel clock. It is possible to obtain a very accurate pulse width.

With this information recording / reproducing apparatus, the mark recorded on the phase-change type medium can be formed into an accurate mark having the same EFM data length, and as shown in FIG. 3B, the RF signal which is a reproduction signal. The (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 show typical values, and are actually optimized depending on the recording material and the media phase configuration. You can adapt the values. Also, 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 of the laser light on the medium, the length of an even length with respect to the recording channel clock period. The setting of the recording waveform may be exchanged between the recording data having the length and the recording data having the odd length.

As described above, this information recording / reproducing apparatus is
The semiconductor laser L as a light source information onto a recording medium having a recording layer that changes reversibly phase in the crystal phase and an amorphous phase
When recording with the light from D, the light source LD is caused to emit a multi-pulse light including a head heating pulse A, a plurality of rear heating pulses B, a rear cooling pulse C, and a rear cooling pulse Cr, and the recording is performed. In the information recording method for forming marks, when recording the record data of either the even length or the odd length with respect to the recording channel clock cycle T, the pulse width of the rear heating pulse B and the rear cooling pulse C is recorded. Since the channel clock cycle is approximately the same, sufficient heating time and cooling time can be secured, and the predetermined recording mark length can be accurately obtained without increasing the speed of the semiconductor laser drive circuit as the light source drive section. It becomes possible to record.

In addition, this information recording / reproducing apparatus uses the rear heating pulse B when recording the record data of the other mark length with respect to either the even length or the odd length.
The difference between the total sum of the cooling pulse widths and the total sum of the heating pulse widths in the light emitting portions of the rear cooling pulse C and the rearmost cooling pulse Cr depends on the recording data of even length and the recording data of odd length with respect to the recording channel clock period T. Since the width of the rear heating pulse B and the width of the rear cooling pulse C are set so as to be substantially the same, edge shift does not occur in both the even length recording data and the odd length recording data, and as a light source driving unit. A predetermined recording mark length can be accurately obtained without increasing the speed of the semiconductor laser drive circuit, and high-speed recording can be performed.

Further, the light emitting portion of the information recording and reproducing apparatus, the even length with the rear heating pulse and the rear cooling pulse when recording the other mark length of the recording data for one mark length any odd length The width of the heating pulse, the cooling pulse and the heating pulse or the cooling pulse, the heating pulse and the cooling pulse located at the center of 0.75T, 0.
Since it is set to 5T and 0.75T, it is possible to sufficiently increase the pulse widths of the heating pulse and the cooling pulse corresponding to the edge portions before and after the mark and form a sharp edge portion,
It is possible to suppress the jitter of the reproduced signal.

FIG . 4 shows the operation timing of a reference example of the information recording / reproducing apparatus . This information recording / reproducing apparatus is basically the same as the example of the information recording / reproducing apparatus to which the inventions described in claims 1 to 3 are applied, but the following points are mentioned.
This is different from the example of the information recording / reproducing apparatus to which the described invention is applied.

In the information recording / reproducing apparatus to which the invention according to any one of claims 1 to 3 is applied, the heating pulse width is different between the recording mark having the even length and the recording mark having the odd length in the recording waveform. Also, since the regularity of the cooling pulse width is different, a slight deviation occurs in the heating and cooling conditions, and when the recording mark having an odd length is used as a reference, an edge shift occurs in the recording mark having an even length. To do. Since the detection window width Tw of the reproduction signal becomes smaller as the recording density becomes larger, the edge shift causes an error in the data.

Therefore, in this information recording / reproducing apparatus, the multi-pulse light emission waveform is corrected so that the occurrence of such edge shift can be prevented and the error can be reduced. The recording waveforms for the odd-length and even-length recording marks are the same as those of the example of the information recording / reproducing apparatus to which the invention described in claims 1 to 3 is applied. The recording waveforms for the odd-numbered recording marks are 3T, 5T, 7 with the pulse widths of the heating pulse and the cooling pulse other than the first heating pulse A being all 1T.
No edge shift occurs between the T, 9T and 11T marks.

Therefore, in this information recording / reproducing apparatus,
For the recording waveforms for the even-numbered recording marks with irregular mark lengths, the following corrections are performed by the light intensity control means composed of a digital circuit. First, the recording waveform for a recording mark having a length of 4T or 8T is such that the heating pulse B located at the center of the subsequent portion excluding the first heating pulse A has a pulse width of 0.5T and has a sufficient pulse width during high-speed recording. Since it does not exist, an edge shift that shortens the recording mark of odd length occurs.

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

Further, regarding the recording waveform for the recording mark having the length of 6T and 10T, the cooling pulse C located at the center of the subsequent portion excluding the head heating pulse A has a pulse width of 0.
Since the pulse width is not sufficient at the time of high-speed recording at 5T, edge shift occurs such that the trailing edge becomes short 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 or 10T,
The pulse width of the cooling pulse C positioned at the center of the subsequent portion excluding the head heating pulse A is controlled by the light intensity control means each made of a digital circuit, and the pulse width is equal to the edge shift amount α6,
The cooling pulse C is corrected so as to be increased by α10, and is positioned 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 pulse widths of 0.75T.

By carrying out such a correction, the edge shift between the mark having an odd length and the mark having an even length is completely corrected, and higher density recording is possible. In addition, 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.
Since the pulse widths of both are corrected so as to be large, the thinning of the central portion of the recording mark can be improved, and a better reproduction signal can be obtained.

The set value of the recording waveform shows a typical value, and in practice, a value optimized depending on the recording material, the medium phase configuration, etc. may be applied. Also, 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 of the laser light on the medium, the recording data of even length and the recording data of odd length are different. The recording waveform settings may be exchanged with and.

Since the length of the recording mark to be formed depends on the cumulative length of the heating pulse and the cooling pulse, the same effect as described 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 subsequent portion excluding the head heating pulse A, and for example, the edge shift amount is corrected with respect to the pulse width of the tail cooling pulse Cr. You may Further, in the light intensity control means composed of a digital circuit, the means for generating the corrected heating pulse and cooling pulse in multiple stages with high accuracy can be easily configured by a delay circuit such as a multi-tap delay line or a plurality of mono-multivibrators. You can

Thus, in this information recording / reproducing apparatus ,
Any of the rear heating pulses B and the rear cooling pulse C and the light emitting portion of the last cooling pulse Cr when recording the record data having a length of the other mark length with respect to one of the mark length either the even length and odd-length Since the heating pulse or the cooling pulse has been corrected, a slight edge shift due to the difference in the heating / cooling condition of the medium between the recording data having the even length and the recording data having the odd length is completely corrected. It becomes possible .

Next, another reference example of the information recording / reproducing apparatus will be described. Ge-Sb-Te-based and Ge-Te-based recording layers have been used as recording layers for conventionally used phase-change media.
-Sb-S system, Te-Ge-Sn-Au system, Ge-Te
-Sn system, Sb-Se system, Sb-Se-Te system, Sn-
Se-Te system, Ga-Se-Te system, Ga-Se-Te
-Ge system, In-Se system, In-Se-Te system, Ag-
In-Sb-Te system etc. are available.

Every other reference example of [0050] information recording and reproducing apparatus, examples of the claims 1 to 3 information recording and reproducing apparatus which applies the invention described in the reference example of the above mentioned information recording and reproducing apparatus, a phase-change media The Ag-In-Sb-Te-based recording material is used for the recording layer of. When data is recorded on a phase change medium having such a recording layer, the amorphous phase formation is highly dependent on the quenching condition of heating → cooling. Therefore, the heating pulse for forming the mark and the cooling immediately after that. The formation of the mark largely depends on the difference in the emission power from the pulse. Therefore, an example of an information recording / reproducing apparatus to which the invention described in claims 1 to 3 is applied, an example of an information recording / reproducing apparatus to which the invention of claims 1, 2, and 4 is applied, and As compared with the reference example , the mark can be recorded more clearly, and the jitter of the reproduction signal can be suppressed.

Further, 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. 5 , and the recorded data having an even length and the odd length are recorded. It is possible to easily set the lengths of all marks to integral multiples of 1T without causing edge shift with the recording data having a length. Further, the accuracy of the correction can be made extremely high even for a slight edge shift. 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.

Thus, the information recording / reproducing apparatusReference example
The recording layer is made of AgInSbTe-based recording material.
, The accumulation of heating and cooling pulses in the recorded waveform
The relationship between the length and the formed mark length is almost a straight line.
Recorded data with length of several lengths and length of odd length
There is no edge shift with the recorded data,
The accuracy of the correction is extremely high even for edge shift.
It is possible to

[0053]

As described above, according to the first aspect of the invention, it is possible to reversibly change the phase between the crystalline phase and the amorphous phase.
From a light source as a mark of information on a recording medium having a recording layer
When recording with the light of
To emit a recording mark to form a recording mark.
Light is at least the first heating pulse and the last cooling pulse.
As the length of the mark to be recorded increases, including
Interchange between the first heating pulse and the last cooling pulse.
A rear cooling pulse and a rear heating pulse that are inserted into each other
In the information recording method, the recording channel clock
When recording record data with a mark length that is an integral multiple of the period T
In the case where the mark length is odd and even,
In each case, the data length of the recording data is the recording chunk.
Each time the channel clock period T is doubled, the rear part
It must consist of one heating pulse and one rear cooling pulse.
Since one set is added , a sufficient heating time and cooling time can be secured, a predetermined recording mark length can be accurately obtained without increasing the speed of the light source driving unit, and high speed recording can be performed. .

According to the invention of claim 2, claim 1
In the above information recording method, the mark length of the recorded data
Is doubled with respect to the recording channel clock cycle T,
To that of the rear heating pulse and the rear cooling pulse.
When increasing the number of pairs each consisting of one, the rear heating
The sum of the pulse width of the pulse and the rear cooling pulse is
Serial in <br/> the increase 2 times the recording channel clock period T, can ensure a sufficient heating time and cooling time, the light source drive
Accurately obtain a predetermined recording mark length without increasing the speed of parts
Therefore, high-speed recording can be performed.

According to the invention of claim 3, claim 1
Recording of each mark length in the recorded information recording method
Including the shortest mark length of the data, the shortest mark length
Record multiple record data with different mark lengths by 2T each
When increasing, increase 1 according to the increase of the mark length.
A set of pulses for the rear heating pulse and the rear cooling pulse.
The sum of the scan widths to the recording channel clock cycle T
Since it is doubled , secure sufficient heating time and cooling time
It is possible to perform a predetermined recording mark without increasing the speed of the light source driving unit.
The accurate recording length can be obtained and high-speed recording can be performed.
It becomes Noh.

According to the invention described in claim 4, pulse control
Generates a signal and controls the pulse with a semiconductor laser drive circuit
The light source is driven by the drive current according to the signal and multi pulse
In the optical head that emits light of
The light of the information described in any one of claims 1 to 3.
It has a multi-pulse generation means to generate by the recording method
That so it can ensure a sufficient heating time and cooling time, the light source
Precise recording mark length without speeding up the drive unit
Therefore , high-speed recording can be performed.

According to the invention described in claim 5, since the optical head according to claim 4 is provided, sufficient heating time and cooling can be achieved.
Time can be secured and the light source drive unit can be specified without increasing the speed.
It is possible to accurately obtain the recording mark length of the
It becomes possible.

[Brief description of drawings]

FIG. 1 is a block diagram showing a part of an example of an information recording / reproducing apparatus to which the invention described in claims 1 to 3 is 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 shows the operation timing of a reference example of the information recording / reproducing apparatus .
It is a timing chart shown .

FIG. 5 is a heating pattern in another reference example of the information recording / reproducing apparatus .
The relationship between the cumulative length of the loose and cooling pulses and the formed mark length
It is a characteristic view to show .

FIG. 6 is recording data and recording in a conventional information recording method.
It is a figure which shows the example of a waveform and a recording mark .

FIG. 7 is recording data in another conventional information recording system,
It is a figure which shows the example of a recording waveform and a recording mark .

FIG. 8 is for each record data in the same information recording method
It is a wave form diagram which shows a recording waveform .

FIG. 9 is a diagram for explaining the same information recording method .

[Explanation of symbols]

LD laser diode 11-13 Current source 14-16 switching element

Continuation of the front page (56) Reference JP-A-7-21612 (JP, A) JP-A-6-251375 (JP, A) JP-A-6-84224 (JP, A) JP-A-5-62193 (JP , A) JP 3-185628 (JP, A) JP 63-160017 (JP, A) JP 58-182134 (JP, A) JP 3264805 (JP, B2) WO 97/014143 (WO , A1) (58) Fields investigated (Int.Cl. ⁷ , DB name) G11B ^7/ 00-7/013 G11B 7/125

Claims (5)

(57) [Claims] 1. When recording information with a light from a light source as a mark on a recording medium having a recording layer having a reversible phase change between a crystalline phase and an amorphous phase, the light source emits multi-pulse light. perform formation of recording marks Te, light of the multi-pulse, at least the top heating pulse, and a last cooling pulse, and the leading heating pulse according to an increase in the length <br/> the mark to be recorded an information recording method comprising a rear cooling pulse and the rear heating pulse is alternately inserted between the last cooling pulse, in the case of recording the integral multiple of the mark length of the recording data of the recording channel clock period T, the When the mark length is odd and even
In each case , each time the data length of the recording data is doubled with respect to the recording channel clock period T,
1 for each of the rear heating pulse and the rear cooling pulse
Information recording method characterized by increasing the number of groups consisting of one
Law . 2. An information recording method according to claim 1, before
Each time the mark length of the recording data increases by a factor of 2 with respect to the recording channel clock period T, when the number of sets each including one of the rear heating pulse and the rear cooling pulse is increased by one, the rear heating pulse and the rear heating pulse are increased. An information recording method , wherein the total sum of the pulse widths of the rear cooling pulses is doubled with respect to the recording channel clock period T. 3. The information recording method according to claim 1, wherein a plurality of record data including the shortest mark length among the record data of each mark length and having a mark length different by 2T from the shortest mark length are recorded. To increase the mark length
The information recording method , wherein the sum 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 period T in accordance with the increase. 4. An optical head which generates a pulse control signal and drives a light source with a drive current according to the pulse control signal in a semiconductor laser drive circuit to emit multi-pulse light . A mark generated by the information recording method described in any one of Items 1 to 3.
An optical head having a chi-pulse generation means . 5. An information recording apparatus comprising the optical head according to claim 4.