JPH1083553A - Information recording method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a high density recording even when a relative speed between an energy beam and an information recording medium changes for information recording media having various cooling speeds. SOLUTION: This method performs information recording by irradiating an information recording medium with a recording energy beam by power modulating the beam on a high power level and an intermediate power level lower than the high power level. At this time, recording is performed by a recording waveform having a pulse downward a power level P11 lower that the intermediate power level Pm1 after a continuous high power pulse train having a power level Ph1 and the width of the downward pulse is changed according to the relative speed between the energy beam and the information recording medium.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recording information on an information recording medium on which information can be recorded by irradiating an energy beam. The present invention relates to an information recording method and an information recording apparatus using the information recording method.

[0002]

2. Description of the Related Art Conventional recording on a rewritable recording film
The erasing method may be, for example, a method using a magneto-optical disk having a two-layer exchange-coupling film as a recording film, as disclosed in JP-A-62-175948, and a method disclosed in JP-A-62-275.
In the case of using a recording film for a phase-change type optical disc capable of high-speed erasing, which can perform crystallization in almost the same time as the laser irradiation time for recording shown in JP-A-59229, the power of one energy beam is increased. In each case, at least two levels higher than the read power level, that is, at least between a high power level and an intermediate power level are changed. This method has an advantage that so-called overwriting (rewriting by overwriting) in which new information is recorded while erasing existing information is possible.

[0003] Also, Japanese Patent Application Laid-Open No. 62-259229,
As shown in JP-A-3-185629,
By changing the energy beam between three levels, a high power level, an intermediate power level, and a lower power level than the intermediate power level, the recording mark becomes teardrop-shaped (comparing the recording mark to the front. The phenomenon can be suppressed.

[0004]

At present, the development of digital video discs is at the final stage, and rewritable digital video discs (DVD-Rs) using a phase-change recording film are being developed.
AM) is also under development. Like DVD-RAM,
In an optical disc device that performs mark edge recording on a phase change recording film, in order to prevent mark shape distortion and disappearance, recording is performed anywhere on the outer edge of the area where the recording film is melted to form recording marks on the recording film. It is necessary that the temperature reached and the cooling rate be almost the same. However, various recording waveforms known so far cannot sufficiently satisfy the above condition, and there is a limit to a achievable recording density.

On the other hand, in recent years, with the increase in the speed of digital signal processing, there is an increasing demand for faster recording and reproduction of information recording devices. In order to meet this demand, it is important to increase the relative speed between the energy beam and the information recording medium.

[0006] By increasing the relative speed between the energy beam and the information recording medium, more information can be recorded and reproduced in a unit time, so that the data transfer rate of the information recording and reproducing apparatus can be improved. Normally, the recording speed on an information recording medium increases with the progress of product generations. Therefore, in consideration of compatibility between generations, a single information recording / reproducing apparatus is used for both an information recording medium compatible with high-speed recording (slow cooling structure) and an information recording medium compatible with low-speed recording (rapid cooling structure). It is desirable to be able to perform high-speed recording and reproduction.

In order to speed up recording and reproduction by moving between recording tracks on a disc-shaped information recording medium having greatly different radii from the center, the information recording medium is rotated at a constant angular velocity. It is important to make it happen. Since the time for making the relative speed between the energy beam and the information recording medium constant (the time for changing the angular velocity) can be omitted, the access time of the recording / reproducing apparatus can be shortened.

Further, as described above, there is a great demand for recording a large amount of information such as a video signal processed by digital signal processing. Therefore, an invention of an information recording method capable of performing high-speed recording at high speed is also urgently needed.

In order to realize an information recording apparatus satisfying the above conditions, even when the relative speed between the energy beam and the information recording medium is large, the energy beam and the information recording medium having various cooling rates can be used. There is a demand for an information recording method capable of performing stable recording even when the relative speed of the information recording medium changes or when the recording density is extremely high.

Although the above prior art is a very excellent idea, it is useful for the case where the cooling speed difference between the media, the relative speed between the energy beam and the information recording medium is large, and the case where there is a cooling speed difference accompanying the change. Consideration or consideration for high-density recording, in which the distance between recording marks is less than half of the energy beam spot, cannot be said to be sufficient.

For example, when recording is performed by irradiating a high power level energy beam to an information recording medium having a low cooling rate, the recording film and the protective films on both sides thereof are irradiated later by heat storage. The higher the temperature, the higher the temperature, and the rear part of the recording mark spreads in a direction perpendicular to the recording track (a tear-drop shape), causing distortion in the reproduced signal. In the above prior art, the energy density in the front part of a series of high power pulse trains is increased or the level between high power pulses is made smaller than the intermediate power level in order to prevent the recording mark from becoming teardrop-shaped.

Therefore, when the relative speed between the energy beam and the information recording medium increases, or when recording is performed on an information recording medium having a relatively high cooling rate,
The front part of the recording mark tends to be larger than the rear part (it becomes an inverted teardrop shape), and if the signal from such a part is reproduced, the reproduced signal will be distorted, so that it corresponds correctly to the recording signal. However, there arises a problem that a reproduced signal cannot be obtained.

When performing high-density recording in which the distance between recording marks is less than half of the energy beam spot, the distance between recording marks becomes small. Due to the influence of heat (thermal interference), distortion occurs in the recording mark. In the prior art, measures to lower the power level of the energy beam (laser power level) after the recording pulse to a level lower than the erasing power level have been taken in order to suppress the thermal interference. However, high-speed, high-density recording, particularly the shortest mark length and the shortest When the space length is 1 μm or less and the relative speed between the laser beam and the recording medium is 9 m / s or more, a technique for further suppressing thermal interference is required.

Therefore, an object of the present invention is to solve the above-mentioned problems in the prior art, and to improve the recording speed of an information recording medium having various cooling speeds and the relative speed between an energy beam and an information recording medium. It is an object of the present invention to provide an information recording method and an information recording apparatus which enable accurate recording even when the relative speed is large or when the relative speed changes.

Further, a technique for narrowing track pitch has been developed for high-density recording. For example, there is a method of recording information in both a groove (groove) and a land (region between grooves) provided on an information recording medium. In this method, the groove depth (optical phase difference between land and groove)
Is set to an appropriate value, the reproduction signal crosstalk from the land to the groove or from the groove to the land can be canceled.

However, since the heat generated by the energy beam is used for recording information, especially when the control of the position of the energy beam becomes unstable (for example, when a track offset occurs), Since thermal interference occurs on an adjacent track (an adjacent groove with respect to a land or an adjacent land with respect to a groove), there is a problem that information recorded on an adjacent track is erased.

Therefore, another object of the present invention is to
Even when information is recorded on an information recording medium having a narrow track pitch, particularly an information recording medium corresponding to land-groove recording, such that the track pitch is equal to or smaller than the recording energy beam diameter, the information on the adjacent track is not erased. Another object of the present invention is to provide an information recording method and an information recording device that enable accurate recording.

Another important issue is to improve the recording sensitivity.
Normally, when the relative speed between the information recording medium and the energy beam is increased, the time required for the energy beam to pass through a recording point on the information recording medium is shortened, so that the amount of energy applied to the information recording medium in a unit time is reduced Then, the recording point is hardly heated (recording sensitivity is reduced). In addition, when recording is performed on an information recording medium that is likely to store heat, the recording point is kept at a high temperature for a long time, so that deterioration occurs due to heat.
Therefore, in order to improve the reliability of the information recording medium, the information recording medium is provided with a heat-dissipating layer having a high thermal conductivity such as a metal so that the heat of the heated portion is quickly diffused. In such a case, during recording, energy is applied while diffusing heat, so that the recording sensitivity is reduced.

Therefore, another object of the present invention is to
Even when the relative speed between the information recording medium and the recording energy beam is increased, or when recording on an information recording medium having a structure that is easily cooled rapidly, information that enables accurate recording without lowering the recording sensitivity And an information recording apparatus.

[0020]

In order to solve the above-mentioned problems in the prior art, the following information recording method, information recording device, and information recording medium may be used. That is, (1) an information recording method for recording information by irradiating a recording energy beam with at least a high power level and an intermediate power level lower than the high power level on an information recording medium. In, after a continuous high power pulse train, recording is performed by a recording waveform having a downward pulse to a power level lower than the intermediate power level, and the width of the downward pulse is determined according to the relative speed between the energy beam and the information recording medium. An information recording method characterized by changing.

By using the above information recording method, the cooling speed at the rear of the recording mark can be controlled by changing the width of the downward pulse, and the following effects are obtained.

Normally, when the relative speed between the energy beam and the information recording medium is low, the recording marks tend to be teardrop-shaped. In this case, the width of the rear part of the recording mark can be reduced by reducing the cooling rate of the rear part of the recording mark.
Further, when the relative speed between the energy beam and the information recording medium is large, the recording mark tends to have an inverted teardrop shape. In this case, the width of the rear part of the recording mark can be increased by increasing the cooling rate of the rear part of the recording mark.

(2) For the information recording medium, the recording energy beam is set to at least a high power level,
In an information recording method in which information is recorded by irradiating with power modulated at an intermediate power level lower than the high power level, and a test write is performed on the information recording medium prior to the information recording, the information recording method may be modified as follows. An information recording method in which recording is performed using a recording waveform having a downward pulse to a power level lower than the intermediate power level after a continuous high power pulse train, and the width of the downward pulse is changed.

In the information recording method described above, when recording is performed on an information recording medium having a slow cooling structure in which the recording mark tends to have a teardrop shape, the cooling rate at the rear of the recording mark is reduced to reduce the width of the rear portion of the recording mark. When recording on an information recording medium with a quenching structure in which the recording mark tends to be a reverse teardrop type, the width of the rear part of the recording mark can be increased by increasing the cooling rate of the rear part of the recording mark. it can.

The above information recording method is particularly effective for an information recording medium on which information is recorded utilizing a phase change between a crystal and an amorphous phase (a so-called phase change recording medium).

Further, by changing the width of the downward pulse, it is possible to minimize the thermal interference at the time of recording the preceding and succeeding recording marks, so that the distance between the recording marks can be reduced. Therefore, high-density recording becomes possible. Such an effect is significant not only for a phase-change recording medium but also for an information recording medium, such as a magneto-optical disk, which generally records information using heat generated by energy beam irradiation.

Further, the downward pulse described in (1) and (2) can be added to the interval between the last pulse of the continuous high power pulse and the first pulse of the next continuous high power pulse train, whereby the present invention can be applied. Although an effect appears, a particularly great effect appears when added immediately after the last pulse of a continuous high power pulse train.

In the present invention, a continuous high-power pulse train is a high-power pulse train required to form one recording mark, which is generally shorter than the channel clock and arranged at substantially equal intervals. Therefore,
When a single high power pulse includes a case where one recording mark is recorded, this is also referred to as a continuous high power pulse train.

The product of the irradiation time of the downward pulse and the relative speed of the energy beam and the information recording medium is the energy beam spot diameter (the center intensity of the energy beam).
If the distance is less than one-third of (exp (-2) or more, the distance in the recording track direction), the distortion of the reproduction signal is particularly small, so that it is optimal for high-density recording. When the product of the irradiation time of the downward pulse and the relative speed of the energy beam and the information recording medium is one third or more of the spot diameter of the energy beam, erasing is performed at an intermediate power level (crystallization in the case of a phase change recording film). Is not performed sufficiently, so that the signal quality is degraded.

(3) By irradiating the information recording medium with a recording energy beam at least at a high power level and at an intermediate power level lower than the high power level, the recording energy beam has a plurality of lengths. In an information recording method for forming a recording mark and recording information, at least the shortest mark is recorded using a continuous high power pulse train, and the power level of the first pulse is compared with the power level of the last high power pulse. By using an information recording method characterized by the fact that the width is large, the width of the front part of the recording mark and the width of the rear part of the recording mark can be controlled independently, which is suitable for high-density recording. When the shortest mark is recorded using one high power pulse, it means that the first pulse and the last pulse match, so if the height of the high power pulse is also one type, the width of the recording mark in front of the recording mark In addition, it becomes impossible to independently control the width of the recording mark at the rear of the recording mark, and in order to achieve high-density recording, special consideration such as adjusting the cooling rate of the information recording medium to the recording waveform is required. On the other hand, if the power level of the first pulse is lower than the power level of the last high power pulse, the amount of energy applied to the front of the recording mark is insufficient, so that the recording mark becomes teardrop-shaped, which is not preferable.

(4) In an information recording method for irradiating a beam having energy onto an information recording medium to form a mark having a plurality of lengths and recording information, one of the marks is recorded. In this case, the energy beam is irradiated as a pulse train, and the falling level of the pulse train closest to the head of the mark is set higher than the falling level of the next pulse train. Alternatively, a recording mark having a plurality of lengths is formed on the medium by irradiating the recording energy beam with at least a high power level and a power modulation at an intermediate power level lower than the high power level to form a recording mark having a plurality of lengths. In the information recording method for performing the recording of at least, the shortest mark is recorded using a continuous high power pulse train, the power level immediately after the first pulse is equal to or higher than the power level immediately after the high power pulse other than the first pulse. The information recording method used is used. This makes it possible to independently control the width of the front part of the recording mark and the width of the rear part of the recording mark, so that it is suitable for high-density recording. On the other hand, if the power level immediately after the first pulse is lower than the power level immediately after a high power pulse other than the first pulse, the amount of energy applied to the front of the recording mark is insufficient, so that the recording mark becomes teardrop-shaped, which is not preferable.

Further, the information recording method described in (3) and (4) is used together, that is, at least the shortest mark is recorded using a plurality of high power pulses, and the power level of the first pulse is the last. By using an information recording method characterized by being larger than the power level of the high power pulse and the power level immediately after the first pulse being equal to or higher than the power level immediately after the high power pulse other than the first pulse, Suitable for high density.

The recording waveforms described in (3) and (4) are effective for controlling the mark shape at the head of the recording mark, and effective for controlling the mark shape at the rear of the recording mark (1).
A particularly great effect can be obtained by using the information recording method in combination with the method (2).

(5) For the information recording medium, the recording energy beam is set to at least a high power level,
In an information recording apparatus for recording information by power-modulating and irradiating at an intermediate power level lower than a high power level, a down pulse to a power level lower than the intermediate power level is provided after a continuous high power pulse train. Generate a recording waveform and change the width of the downward pulse to
An information recording apparatus, comprising: a recording waveform generator that changes the energy beam according to a relative speed between an energy beam and an information recording medium.

Alternatively, (6) For the information recording medium,
Information recording is performed by irradiating the recording energy beam with at least a high power level and an intermediate power level lower than the high power level and irradiating the information beam, and a test write is performed on the information recording medium prior to the information recording. In the information recording apparatus, a recording waveform having a downward pulse to a power level lower than the intermediate power level is generated after a continuous high power pulse train at the time of the test writing, and the width of the downward pulse is changed. By an information recording device characterized by having a waveform generating means,
(1) Since the information recording method described in (2) can be realized, high-density recording can be performed even when the relative speed between the energy beam and the information recording medium changes.

(7) The information recording medium is irradiated with a recording energy beam at least at a high power level and at an intermediate power level lower than the high power level, so that the recording energy beam has a plurality of lengths. In an information recording apparatus that forms a recording mark and records information, at least at the time of recording the shortest mark, a continuous high-power pulse train is generated, and a recording waveform is generated in which the power level of the first pulse is higher than the power level of the last pulse. An information recording device comprising means.

Alternatively, (8) For the information recording medium,
An information recording apparatus for recording information by forming recording marks of a plurality of lengths by irradiating a recording energy beam at least at a high power level and at an intermediate power level lower than the high power level and irradiating it. In at least the shortest mark recording, there is provided a recording waveform generating means for generating a continuous high power pulse train and making the power level immediately after the head pulse equal to or higher than the power level immediately after the high power pulse other than the head pulse. Since the information recording apparatus can realize the information recording methods described in (3) and (4), high-density recording can be performed on information recording media having various cooling rates.

A recording waveform generating means using the information recording method described in (3) and (4), that is, a plurality of high power pulses are generated at least at the time of recording the shortest mark, and the power level of the head pulse is changed. It is larger than the power level of the last high power pulse, and
Use of an information recording apparatus characterized by having a recording waveform generating means for setting the power level immediately after the first pulse to be equal to or higher than the power level immediately after a high power pulse other than the first pulse is more suitable for higher density.

As described above, by using the information recording methods (1) and (2) and the information recording methods (3) and (4) together, there is a particularly large recording mark shape control effect. (5) The recording waveform generating means shown in (6),
(7) By using an information recording apparatus capable of generating a recording waveform by using the recording waveform generating means shown in (8) together, an energy beam and information recording can be performed on information recording media having various cooling rates. High-density recording is possible even when the relative speed of the medium changes.

The effect of the present invention appears when the power level of the downward pulse added after the continuous high power pulse is lower than the intermediate power level at which the recording mark can be erased. In particular, when the power level of the downward pulse is lower than the intermediate power level and equal to or lower than the reproduction power level for reproducing information, not only can the recording waveform of the present invention be easily formed, but also the recording waveform on the medium can be easily formed. Since the effect of controlling the cooling rate increases, the effect of achieving high-density recording on information recording media having various cooling rates increases even when the relative speed between the energy beam and the information recording medium changes.

Further, if an information recording medium in which an amorphous recording mark is recorded in a crystal and crystal grains larger than the crystal grain of the crystal exist around the recording mark, a recrystallization area can be obtained. Can be easily controlled by the attained temperature and the cooling rate, so that the recording mark does not easily become a teardrop type or a reverse teardrop type, and the fluctuation of the size of the recording mark can be suppressed as much as possible. Therefore, a reproduced signal faithful to the recording waveform can be obtained. However, the present invention is also applicable to a recording medium having other characteristics such as a recording medium occupied entirely by large crystal grains.

Further, (9) information is recorded by irradiating the information recording medium with a recording energy beam at least at a high power level and an intermediate power level lower than the high power level. In the information recording method, between each high power pulse of the continuous high power pulse train, and after the continuous high power pulse train, recording was performed with a recording waveform having a downward pulse to a power level lower than the intermediate power level, and the continuous recording was performed. Information recording at various cooling rates by using an information recording method characterized in that the width of the downward pulse after the high power pulse train is 0.8 times or more and 2.2 times or less of the recording waveform generating clock. High-density recording can be achieved on the medium without changing the width of the downward pulse after the continuous high-power pulse train. Can.

(10) Information recording is performed on the information recording medium by irradiating the recording energy beam with at least a high power level and an intermediate power level lower than the high power level. In the information recording method, between each high power pulse of the continuous high power pulse train, and after the continuous high power pulse train, recording was performed with a recording waveform having a downward pulse to a power level lower than the intermediate power level, and the continuous recording was performed. (9) The information recording apparatus according to (9), further comprising a recording waveform generating means for setting the width of the downward pulse after the high power pulse train to be 0.8 to 2.2 times the recording waveform generating clock. An information recording method can be realized.

(11) The information recording method according to (9), wherein the width of the downward pulse after the continuous high power pulse train is set to an integral multiple of 1/2 the channel clock. The use of the information recording method described above is preferable because the circuit scale of the recording waveform generating means can be minimized. Even when the width of the downward pulse after the continuous high-power pulse train is set to an integral multiple of the channel clock, the effect of the present invention is exhibited, but it is considered that it is preferable to generate a high-power pulse equal to or less than the width of the channel clock. Then, a divided pulse smaller than the width of the channel clock is required, which does not contribute to a reduction in the circuit size of the recording waveform generating means. On the other hand, when the width of the downward pulse after the continuous high power pulse train is increased to an integral multiple of 1/3 times the channel clock or an integral multiple of 1/4 times the channel clock number, This is preferable because the width of the downward pulse after the high power pulse train can be optimized with higher accuracy, but the circuit scale becomes large.

(12) The information recording apparatus according to (10), wherein the width of the downward pulse after the continuous high power pulse train is set to an integral multiple of 1/2 the channel clock. The information recording method according to (11) can be realized by an information recording apparatus characterized by having means.

Further, the information recording method according to (13) or (4), wherein the power level immediately after the first pulse is 70% to 140% of the intermediate power level. By using this, the width of the front part of the recording mark and the width of the rear part of the recording mark can be controlled independently, which is suitable for high-density recording. Although good recording can be performed when the power level immediately after the first pulse is 70% or less of the intermediate power level or 140% or more, good recording can be performed. In particular, when the ratio is 100% or more and 120% or less, a particularly large signal quality improvement effect appears.

(14) The information recording apparatus according to (8), further comprising a recording waveform generating means whose power level immediately after the first pulse is 70% or more and 140% or less of the intermediate power level. By using the information recording device described above, the information recording method of (13) can be realized.

Further, (15) (1) to (4),
(9) The information recording method according to (11) or (13), wherein the information is recorded on both lands and grooves on the information recording medium.
Even when information is recorded on an information recording medium having a narrow track pitch, particularly an information recording medium corresponding to land-groove recording, such that the track pitch is equal to or smaller than the recording energy beam diameter, the information on the adjacent track is not erased. , Accurate recording becomes possible. Also, since the cooling rate of the recording film is different between the land and the groove, the width of the downward pulse after the continuous high power pulse train is different between when recording information on the land and when recording information on the groove. It may be different.

Also, (16) (5)-(8), (1)
The information recording apparatus according to (0), (12) or (14), further comprising tracking servo means for recording information on both lands and grooves on the information recording medium. The information recording method of (15) can be realized by the device.

When the shortest mark is recorded by a plurality of high power pulses, the energy of the energy beam applied to the first high power pulse and the last high power pulse is changed to a high power pulse other than the first and last high power pulses. When the energy is larger than the energy applied to the pulse, a particularly low jitter value is obtained. This effect is achieved when the disk linear velocity is 9 m / s.
, Or in high-density recording where the shortest mark length is less than 2/3 of the laser beam diameter.

As described in detail above, the basis of the present invention is to precisely control the cooling rate of the recording film after the irradiation of the energy beam. Therefore, (1) to (16)
The information recording method and the information recording apparatus described in (1) have a particularly large effect on an information recording medium (a so-called phase change recording medium) on which information is recorded using a phase change between a crystal and an amorphous. That is, the shape of the recording mark recorded on the phase change recording medium is extremely sensitive to the cooling rate of the recording film after the energy beam irradiation.

The width of the high-power pulse described above,
Alternatively, the width of the pulse, such as the width of the downward pulse after the continuous high-power pulse train, is between the minimum value and the maximum value of the differential value of the time change of the energy of the energy beam irradiated on the information recording medium. Although the time is indicated, more precisely, the time between the minimum value and the maximum value of the time derivative signal of the higher-order electric signal (such as a digitized electric signal for generating a recording waveform) is indicated. I have. When the time between the minimum value and the maximum value is quantized, the quantized width is referred to as the pulse width. In addition, even if there is a minute fluctuation in the time between the minimum value and the maximum value of the time change of the energy of the energy beam irradiated on the information recording medium, it is quantized as described above. If the fluctuation is of such a degree that the determination is made, the effect of the present invention is not lost.

Needless to say, the time described in the present invention is not an absolute time, but an uppermost clock (channel clock: an electric signal immediately after passing through a modulator such as an EFM modulator or an 8-16 modulator). (A clock corresponding to the basic clock). Therefore, when the channel clock changes according to the relative speed of the energy beam and the information recording medium, the pulse width should be defined in consideration of the relative relationship between the changed channel clock.

The power level refers to an average energy level in each pulse (within the time between the minimum value and the maximum value). In the case where the average energy level corresponds to the voltage level of a digitized electric signal for generating a recording waveform, it is more accurate to determine the average energy level in consideration of the correspondence.

It is preferable to change the width of the high power pulse according to the relative speed between the energy beam and the information recording medium, since the cooling rate of the recording film of the information recording medium can be controlled to an appropriate value (for example, At low linear velocities, the width of the high power pulse is narrowed, etc.), and the circuit scale of the recording waveform generating means becomes large. On the other hand, even when the relative speed between the energy beam and the information recording medium changes, there is an advantage that the circuit scale of the recording waveform generating means is small unless the width of the high power pulse is changed. In this case, the width of the downward pulse after the continuous high-power pulse train may be changed.

In order to improve the recording sensitivity, which is one of the objects of the present invention, energy is excessively distributed at least to the beginning and end of a series of continuous high power pulse trains for recording the longest mark. What is necessary is just to record using a recording waveform. Specifically, (17) for an information recording medium,
An information recording method for recording information by forming a recording mark having a plurality of lengths by irradiating a recording energy beam at least at a high power level and irradiating with a power modulated at an intermediate power level lower than the high power level. ,
At least the longest mark is recorded using a continuous high power pulse, and the power level immediately after the first high power pulse and the power level immediately before the last high power pulse in a series of continuous high power pulse trains are other high power pulses. An information recording method characterized by being larger than the power level between power pulses may be used.

Further, in the information recording method according to (18) or (17), the power level immediately after the first high power pulse and the power level immediately before the last high power pulse in a series of continuous high power pulses are obtained. The information recording method according to (19) or (18), wherein the power level is higher than the power level between the high power pulses other than the first and last power pulses and is 200% or less of the intermediate power level. An information recording method, wherein the shortest mark is recorded by two high power pulses, the second short mark is recorded by three high power pulses, and the third short mark is recorded by four high power pulses. The power level between the first and second high power pulses during mark recording and the power level between the first and second high power pulses during second short mark recording Level and the power level between the first and second high power pulses and the third and fourth high power pulses during the third short mark recording are 50% or more and 170% of the intermediate power level. An information recording method characterized by the following: (20)
(19) The information recording method according to (19), wherein the power level between the second and third high power pulses at the time of recording the second shortest mark and the second and third power levels at the time of recording the third shortest mark. An information recording method characterized in that the power level during the high power pulse is 50% or less of the intermediate power level.

As described above, the range of the power level immediately after the first high power pulse and the power level immediately before the last high power pulse in the series of continuous high power pulse trains is a range other than the first and last high power pulses. Of the intermediate power level greater than the power level between the high power pulses of
When it is 00% or less, and more preferably when it is 50% or more and 170% or less of the above-mentioned intermediate power level, a particularly large signal quality improving effect appears.

In a series of consecutive high power pulse trains, the power level immediately after the first high power pulse and the power level immediately before the last high power pulse may be different values. The effect of the present invention is not lost. Therefore, at least the setting of the power level immediately after the first high power pulse and the setting of the power level immediately before the last high power pulse (for example, a logical value in the recording waveform generation circuit) may be equal. In this case, the recording waveform generation circuit can be simplified, which is advantageous in circuit design. In particular, the power level immediately after the first high power pulse and the power level immediately before the last high power pulse in a series of consecutive high power pulse trains are the same as the intermediate power level between the series of high power pulse trains. , The recording waveform generation circuit can be most simplified. Also, after a series of successive high power pulse trains,
When a downward pulse (cooling pulse) having a lower power than the intermediate power level is provided, the recording waveform is generated by setting the power level of the cooling pulse equal to the power level between the high power pulses other than the first and last power pulses. This is preferable because the circuit scale of the circuit can be further simplified. In this case, there are three types of power level setting values: a power level of a high power pulse, an intermediate power level between a series of continuous high power pulse trains, and a power level lower than the intermediate power level. It can be very simple.

For example, when a mark of a certain length is recorded by three high power pulses, the power level immediately after the first high power pulse and the power level immediately before the last high power pulse are defined as an intermediate power level. Then, the power levels between the three high power pulses are all intermediate power levels, and the heat generated by the first or second high power pulse becomes an excessive heat flow and flows to the trailing edge of the mark, The width of the rear end portion is unnecessarily large. In this case, only one of the power levels immediately before the first (first) high power pulse and the power level immediately before the last (third) high power pulse is lower than the intermediate power level. Better to level. In particular, when the power level immediately before the last (third) high power pulse is lower than the intermediate power level, the excess heat flow generated by the first or second high power pulse can be attenuated.
More preferred.

In the above description, a case where a mark of a certain length is recorded by three high power pulses has been described.
It can also be applied to the case where recording is performed with two or four high power pulses. In other words, when a mark of a certain length is recorded by two high power pulses, the power level immediately after the first pulse and the power level immediately before the last pulse indicate the same level. Even if the level is lower than the level, a good mark may be formed. Further, when recording is performed using four high power pulses, even if the power level immediately after the first high power pulse and the power level immediately before the fourth high power pulse are set to the intermediate power level, the second high power pulse If the power level between the first and second high power pulses is set to be equal to or lower than the intermediate power level, the excess heat flow generated by the first or second high power pulse is attenuated. It is unlikely that the width of the trailing edge of the recording mark will be increased more than necessary. However, depending on the structure of the information recording medium, the width of the trailing edge of the recording mark may be increased more than necessary. Again,
By lowering either the power level immediately after the first high power pulse or the power level immediately before the fourth high power pulse to a power level equal to or lower than the intermediate power level, the width of the rear end of the recording mark can be adjusted appropriately. The size can be controlled.

In order to improve the recording sensitivity, in addition to the above-described method, at least the width of the leading and trailing high power pulses of a continuous high power pulse train used for recording the longest mark is determined. In this case, when the shortest mark or the second or third shortest recording mark is recorded, the interval between the first high power pulse and the last high power pulse becomes narrow, and the longest mark becomes longer. And the like, the amount of irradiation energy per unit area becomes excessive as compared with the case of forming a relatively long mark, and as a result, a relatively short mark tends to be longer than a normal length. In order to solve this problem, (21) the information recording medium is irradiated with a recording energy beam at least at a high power level and at an intermediate power level lower than the high power level, thereby irradiating a plurality of recording energy beams. In an information recording apparatus for recording information by forming a recording mark having a length, at least the power level of the high power pulse for recording the shortest mark is the power level of the high power pulse for recording the longest mark. Information recording method characterized by being lower than
The information recording method according to (21), wherein at least:
Of the high power pulses for recording the shortest mark, the power level of the high power pulse with the lowest power level is lower than any of the power levels of the high power pulse for recording the longest mark, and the longest mark is recorded 75% of the power level of the high power pulse of the lowest power level among the power levels of the high power pulse for performing
What is necessary is just to use the information recording method characterized by the above.

As described above, since the high power level for recording at least the shortest mark is lower than the high power level for recording the longest mark, the excess heat generated at the time of recording the shortest mark is obtained. Can be reduced, and the shortest mark length can be a regular length. However, the high power level for recording the second or third shortest mark is changed to the high power level for recording the longest mark. By lower than the level, 2
The amount of excess heat generated when the third or third shortest mark is recorded can be reduced, and the length of the second or third shortest mark can be made a regular length. preferable. Also, at this time, as the length of the mark to be recorded is increased, the level of the high power pulse is increased, the irradiation energy amount per unit area when recording all the recording marks is averaged, and all the recording marks are recorded. Because it is possible to make it a regular length,
Further suitable for higher density recording.

The range of the high power level for recording the shortest mark is about 75% or more of the high power level for recording the longest mark, whereby the quality of the reproduced signal is improved and the shortest mark is recorded. The effect of the high power level for recording the longest mark is lower than the high power level for recording the longest mark. Particularly when the high power level for recording the shortest mark is 85% or more and 95% or less of the high power level for recording the longest mark, a particularly great effect is exhibited. When the high power level for recording the shortest mark is lower than 75% of the high power level for recording the longest mark, the effect of the present invention does not appear.

As described above, the width of the first and last high power pulses in a series of continuous high power pulse trains is made larger than the width of the first and last high power pulses, and at least the high power of the shortest mark is obtained. By using a recording waveform in which the power level of the pulse is set lower than the power level of the longest mark, the recording sensitivity is improved and good recording can be performed.

Further, (23) the information recording medium is irradiated with the recording energy beam at least at a high power level and at an intermediate power level lower than the high power level, so that the recording energy beam has a plurality of lengths. In an information recording apparatus that forms a recording mark and records information, a recording that generates at least one recording waveform among recording waveforms according to the information recording method described in (17) to (22). When the relative speed between the information recording medium and the recording energy beam is increased by using the information recording apparatus characterized by having the waveform generating means, or when recording is performed on the information recording medium having a structure that is easily cooled rapidly. In addition, it is possible to provide an information recording apparatus capable of performing accurate recording without lowering the recording sensitivity.

[0067]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the following examples.

Embodiment 1 FIGS. 1 to 4 are explanatory diagrams showing recording waveforms according to an embodiment of the present invention. Here, Ph1 and Ph2 are high-level powers at which recording is possible, Pm1 and Pm2 are medium-level powers, Pl
1, P12 indicates low power. T indicates the width of the channel clock, and the division width of the recording pulse is T /
The recording is performed at substantially equal intervals of 2 (in FIGS. 1 to 3, the width of the high-power pulse is substantially T / 2, and in FIG. 4, only the width of the first pulse is substantially T). .). Of course, the division width of the recording pulse is T
/ 2, not T /
The effect of the present invention has been confirmed if the channel clock is an integer multiple of 1 / integer, such as 3, T / 4. However,
The width of the high-power pulse or the width of the cooling pulse (the downward pulse added after a series of continuous high-power pulse trains is called the cooling pulse) is determined by the channel clock T.
It is preferable to use an integral multiple of 倍 of the above because the circuit scale of the recording waveform generation circuit can be minimized. When the number of divisions of the number of channel clocks is increased to an integer multiple of 1/3 or 1/4 of the channel clock T, the width can be more accurately optimized. However, it is not preferable that the circuit scale becomes large.

The feature of the recording waveform shown in FIG. 1 is that the power level Ph2 of the head pulse H1 may be different from the level Ph1 of the high power pulse other than the head pulse, and the level Pm2 after the head pulse H1 is the information level. May be different from the intermediate power level Pm1 that can be erased. Also, the power level Pl of the downward pulse during high power
2 and the power level P11 of the cooling pulse may be different.

It is to be noted that the levels of Ph1 and Ph2 are levels at which information can be recorded, and Pm1 is a level at which information can be erased. Although the intermediate power level Pm2 is effective even when it is equal to or higher than Pm1, it is also effective when it is equal to or lower than Pm1. It is particularly preferable that Pm1 and Pm2 are the same, since the recording waveform generation circuit can be simplified. When Ph2 is larger than Ph1, Pm
When 2 is lower than Pm1, the effect of the present invention is particularly exhibited.
When Pm2 is equal to or greater than Pm1, Ph2 is equal to Ph1.
In some cases, the effect of the present invention may appear even if it is lower. The condition of the present invention is that P11 is lower than Pm1 in the case of a recording waveform having a cooling pulse. However, Pl2 was effective if it was Ph1 or lower than Ph2.

In the present invention, as described above, the power levels of the pulses of the recording waveform are classified into several types for convenience, but the pulses of each level overshoot or undershoot due to the characteristics of the electric signal. In some cases, the effects of the present invention are not lost if the level is within the range. For example, the second high power pulse H2
Or the level of the last pulse, or the level of the downward pulse during high power after H2, may be different from other equivalent levels, but the effect of the present invention is not lost.

FIGS. 2 to 4 show the recording waveforms having a particularly large effect among the recording waveforms described above.

The characteristic of the recording waveform in FIG. 2 is that Ph2 ≧ Ph1 Ph1> Pm1 Pm1 ≧ Pm2 Pm1> P11 Ph1> P12

The characteristic of the recording waveform in FIG. 3 is that Ph1> Pm1 Ph2> Pm1 Pm2 ≧ Pm1 Pm1> P11 Pm1> P12.

The recording waveform in FIG. 4 has the following characteristics: Ph1> Pm1 Ph2> Pm1 Ph1> Pm2 Ph2> Pm2 Ph1> P12 Ph2> P12 P12> P11

T is varied with the disk linear velocity. When the disk linear velocity is 6 m / s, 36.7 ns, 9
24.4 ns for m / s, 1 for 12 m / s
8.3 ns. Of course, T is determined by the transfer rate of the information recording device or the recording density of the information recording medium.
May change.

FIG. 8 is a block diagram of the information recording apparatus of the present invention. When the information recording medium 1 is mounted, the motor 2 rotates the information recording medium 1 at a constant linear velocity of 6 m / s. In the lead-in area provided on the innermost circumference of the information recording medium 1, information on the recordable disk linear velocity range is recorded in advance as pits, and the recordable disk linear velocity range information read by the optical head 3 is recorded. Is transferred to the system controller 5 via the preamplifier circuit 4. At the same time, the information on the recording waveform and the optimum recording power is similarly transferred to the system controller 5. The system controller 5 controls the motor 2 based on the recordable disk linear velocity range information and the radial position information of the optical head 3.
Is controlled, and the information recording medium 1 is rotated at an appropriate rotation speed.

The recording waveform generating circuit 6 has a cooling pulse width of 0T, 0.5T, 1.0T, 1.5T,
A recording waveform is programmed in the circuit so as to correspond to the case of 2.0T and 2.5T, and recording of a cooling pulse width suitable for the information recording medium 1 is performed by using recording waveform information transferred via the system controller 5. Waveforms can be generated. The laser drive circuit 7 causes the semiconductor laser in the optical head 3 to emit light on the basis of the recording waveform transferred from the recording waveform generating circuit 6, and thereby the information recording medium 1
The recording mark is recorded on the.

First, an EFM (Eight to Forteen Modulation) signal was recorded on a phase change recording medium having an Ag-Ge-Sb-Te recording film by changing the disk linear velocity using the waveform of FIG. . At this time, as an energy beam,
A laser beam having a wavelength of 680 nm was used. The objective lens for narrowing the laser beam on the phase change recording medium used had a numerical aperture of 0.55, and had a laser beam diameter of about 1.2 μm. The recording power was changed as the disk linear velocity increased, but when the disk linear velocity was 6 m / s, each power level was changed to Ph1: 11 mW Ph2: 12.5 mW Pm1: 4.0 mW Pm2: 1.1 mW Pl1: 0 0.5 mW Pl2: 1.2 mW.

Also, a cooling pulse is provided at the end of a continuous high power pulse train, for example, H1 to H10 in FIG. 2, and this width Tc is changed from 0 to 2.5T at intervals of T / 2. Were compared.

FIG. 5 shows the linear velocity dependence of the jitter value using Tc as a parameter. When Tc was 0T, the jitter value was lowest when the disk linear velocity was about 6 m / s, and when the disk linear velocity was 8 m / s or more, the jitter value was greatly increased. However, by setting Tc to 1.5T, the jitter value could be minimized even when the disk linear velocity was about 12 m / s. in this way,
By increasing the cooling pulse width Tc with an increase in the disk linear velocity, a good reproduction signal could be obtained even when the disk linear velocity was increased.

Embodiment 2 FIG. 6 shows the structure of a phase change recording medium having a different cooling rate used in the present embodiment. Disk A is composed of Ag-Ge-Sb-Te recording film and A
The ZnS-SiO2 upper protective layer between the l-Ti reflective film is a thin quenched structure phase change recording medium, and the disk B is composed of an Al-Ti reflective layer and a ZnS
-A phase change recording medium having a slow cooling structure in which a Si interference layer is laminated between upper protective layers of SiO2.

EFM signals were recorded on each disk by using the same recording apparatus as in the first embodiment and using the waveforms shown in FIG. At this time, the disk linear velocity was 9 m / s. At this time, each power level is set for the disc A, Ph1: 11.0 mW Ph2: 11.5 mW Pm1: 4.0 mW Pm2: 4.1 mW P11: 0.5 mW P12: 1.2 mW For the disc B In this case, Ph1: 10.5 mW Ph2: 10.0 mW Pm1: 4.0 mW Pm2: 4.5 W P11: 0.5 mW P12: 1.2 mW The jitter value was measured for each disk when recording was performed by changing the cooling pulse width Tc between 0 and 2.5 T at intervals of T / 2.

FIG. 7 shows the Tc dependence of the jitter value for each disk. Tc for disk A with quenching structure
Is 1.0T, the jitter value becomes the lowest, but in the case of Disc B having the slow cooling structure, the jitter value becomes the lowest when Tc is 2.0T. As described above, by adding a cooling pulse having a width corresponding to the cooling speed of the information recording medium to the end of the high power pulse width, information of good signal quality can be obtained for various information recording media having different cooling speeds. Can be recorded.

Embodiment 3 FIG. 8 is a block diagram of an information recording apparatus according to the present invention. When the information recording medium 1 is mounted, the motor 2 rotates the information recording medium 1 at a constant linear velocity of 6 m / s.
In the lead-in area provided on the innermost circumference of the information recording medium 1, information on the recordable disk linear velocity range is recorded in advance as pits, and the recordable disk linear velocity range information read by the optical head 3 is recorded. Is transferred to the system controller 5 via the preamplifier circuit 4. At the same time, the information on the recording waveform and the optimum recording power is similarly transferred to the system controller 5. The system controller 5 controls the motor 2 based on the recordable disk linear velocity range information and the radial position information of the optical head 3, and rotates the information recording medium 1 at an appropriate rotation speed.

The recording waveform generating circuit 6 has a cooling pulse width of 0T, 0.5T, 1.0T, 1.5T,
A recording waveform is programmed in the circuit so as to correspond to the case of 2.0T and 2.5T, and recording of a cooling pulse width suitable for the information recording medium 1 is performed by using recording waveform information transferred via the system controller 5. Waveforms can be generated. The laser drive circuit 7 causes the semiconductor laser in the optical head 3 to emit light on the basis of the recording waveform transferred from the recording waveform generating circuit 6, and thereby the information recording medium 1
The recording mark is recorded on the. If the recording waveform information cannot be obtained, or if the information recorded using the recording waveform of the cooling pulse width determined based on the recording waveform information cannot be normally reproduced, the test on the information recording medium 1 is performed. Perform test writing in the writing area. For example, when the waveform of FIG. 4 is used, the high power level Ph1 and the intermediate power level Pm
1, and recording is performed using the cooling pulse width Tc as a test writing parameter, and the waveform with the smallest jitter is set as the optimum recording waveform. At this time, in order to simplify the above-mentioned optimization processing, Ph1 = Ph2, Pm1 = Pm2 = P
As l2, a recording waveform was generated. As described above, the optimum recording waveform was determined, and information was recorded on the disks A and B in FIG. 6 and a commercially available magneto-optical disk. As a result, a jitter value of 15% was obtained from any of these disks.
The following good reproduced signals were obtained. The jitter value of the reproduced signal was 11% for the disk A, 8% for the disk B, and 12% for the commercially available magneto-optical disk.

In this case, each power level for each disk and the cooling pulse width Tc for the disk A are as follows: Ph1: 10.5 mW Ph2: 10.5 mW Pm1: 4.0 mW Pm2: 4.0 mW Pl1: 0.5mW Pl2: 4.0mW Tc: 0.0T In the case of disc B, Ph1: 9.5mW Ph2: 9.5mW Pm1: 3.5mW Pm2: 3.5mW Pl1: 0.5mW Pl2: 3.5mW Tc: 1.0T In the case of a commercially available magneto-optical disk, Ph1: 10.0 mW Ph2: 10.0 mW Pm1: 4.0 mW Pm2: 4.0 mW P11: 1.2 mW P12: 4.0 mW Tc:

Also, the waveform of FIG. 2 was optimized and recorded as in the case of the waveform of FIG. 4, and as a result, the jitter value of the reproduced signal was 8% for disk A, 6% for disk B, Commercial magneto-optical disks accounted for 10%. Also, the waveform of FIG. 3 was similarly optimized, and as a result, the jitter value of the reproduced signal was 9% for disk A,
Disk B accounted for 7%, and commercial magneto-optical disk accounted for 10%.

For comparison with the conventional method, the waveform of FIG.
Recording was performed with Tc = 0T without changing the c width.
In this case, normal recording could be performed on the disk A, but the jitter value of the disk B and the commercially available magneto-optical disk was 16% and that of the commercially available magneto-optical disk was 18%. Since normal recording is not performed, the same reproduced signal as the input signal cannot be obtained. Therefore, it was found that by adding a recording waveform generating circuit capable of changing the Tc width to the information recording apparatus, normal recording and reproduction can be performed regardless of the cooling speed of the medium structure.

Also, using the above device, the disk linear velocity was 9 m.
/ S, and the same experiment was performed. As a result, when recording was performed with Tc = 0T without changing the width of the waveform in FIG.
Normal recording could not be performed because the jitter value of all disks was 15% or more, but when the recording waveform was optimized by changing the Tc width, normal recording was performed on all disks. I was able to. The jitter value of the reproduced signal is 9% for disk A and 9% for disk B
10%, and 12% of commercially available magneto-optical disks. Therefore, it was found that by adding a recording waveform shaping circuit capable of changing the Tc width to the information recording / reproducing apparatus, normal recording / reproducing can be performed regardless of the disk linear velocity.

Here, the main operation of the information recording apparatus (the block configuration has been described with reference to FIG. 8) used in the above several embodiments will be described with reference to FIGS. This will be described below.

FIG. 9 is a functional block diagram showing the configuration of the recording waveform generating circuit (block 6 in FIG. 8). 8-bit shift register 6-12, 8-bit data register 6
1, 6-2, 6-3, write (recording) pattern generation table 6-4, 16-bit data register 6-5, 6-
6, 6-7, 16-input, 1-output data multiplexer 6
-8, 6-9, 6-10 and a 5-bit binary counter 6-11. The double channel clock 2fCLK sent from the system controller (block 5 in FIG. 8) is the counter 6-11 from the moment when the write command signal WRRQ-P also sent from the system controller becomes true (high level). And supplies the least significant bit Q0 of the counter 6-11 as a channel clock signal of the shift register 6-12 and sends it back to the system controller. The output Q3 of the fourth bit from the lower end of the counter 6-11 is used as a half-byte clock signal for various registers 6-1 and 6
-2, 6-3, 6-5, 6-6, 6-7 and the pattern generation table 6-4.
Outputs Q0, Q1, Q of all 4 bits from the lower order of -11
2, Q3 are multiplexers 6-8, 6-9, 6-10
As a data selection signal. When the above state, that is, when WRRQ-P is true, the serial signal input WT
DATA is sequentially recorded and shifted in the shift register 6-12 at the timing of the CHCLK, and every time the shift is performed eight times (that is, the Q of the counter 6-11 is changed).
Each time the three outputs change from high level to low level), the 8-bit data stored in the thick register 6-12 moves to the first 8-bit data register (DRA) 6-1. The data stored in 6-1 is moved to a second 8-bit data register (DRB), and similarly, the data stored in the register 6-2 is moved to a third 8-bit data register (DRC). .
The first register 6-1 to the third register 6-
The three stored 24-bit data become the address input of the write pattern generation table 6-4, which is in principle fair in a non-volatile random access memory (RAM). 16-bit configuration). The first parallel data signal output words (Y0 to Y15) are sequentially selected by a first multiplexer 6-8 via a first 16-bit data register 6-5 to become bit serial data WRTP2-P. The second parallel data signal output word (Y1
6 to Y31) correspond to the second 16-bit data register 6-
6 and sequentially selected by the second multiplexer 6-9 to become bit serial data WRTP1-P, and further, the third parallel data signal output word (Y3
2 to Y47) correspond to the third 16-bit data register 6-
, And are sequentially selected by the third multiplexer 6-10 to become bit serial data OOLP-N. The above three types of bit serial data WRTP2-P, WRT
P1-P and COOOLP-N are laser driving circuits (FIG. 8)
Block 7, which will be described in detail later) to generate various laser drive levels. The contents of the write pattern generation table (RAM) 6-4 can be sequentially updated by data transfer from a system control bus (abbreviated as syscon bus) 5-1 of a system controller (block 5 in FIG. 8). is there. Thus, the cooling pulse width TC (see FIGS. 1 to 4) and the like can be easily changed according to the situation.

FIG. 10 is a functional block diagram of the laser drive circuit (block 7 in FIG. 8). APC circuit 7-1, three-system drive current superimposing circuits 7-2, 7-3, 7-4, and 4
System DA converter (DAC) 7-5, 7-67, 7
-7 and 7-8. The output value Vr of the APC DA converter 7-5 is set by data transfer from a system control bus (abbreviated to syscon bus) 5-1 of the system controller (block 5 in FIG. 8). On the other hand, a laser beam is generated by supplying the output current Ir to the semiconductor laser 31, and a part of the laser beam is returned to the monitoring photodiode, so that the monitor current Ipd flows, and the current Ipd resistance R1 and the operational amplifier OP
Converted to voltage by the action of A2 (converted voltage = -Ipd × R1)
Input to the operational amplifier OPA1 via the resistor R2,
As a result, a comparison operation with the output value Vr of the DA converter 7-5 is performed, and the output voltage (proportional to the laser beam intensity) of the OPA2 and the Vr (target value of the laser output power) are balanced. Output current I
r is controlled. The loop gain of the APC circuit is determined by the ratio of the resistors R2 and R3, and the diode D1 is for preventing a superimposed current (described later) from flowing back. On the other hand, if the inverted cooling pulse COOOLP-N is at the high level, the analog switch (ASW) SW1 is in the closed state, and the system control bus (abbreviated as syscon bus) 5-1 of the system controller (block 5 in FIG. 8) is used. Since the output voltage Vm of the first current superimposing DA converter 7-6 set by the data transfer is applied to the base of the transistor Q1, the erasing power (Pm shown in the following (formula 1), FIG. (See FIG. 4) The superimposing current △ Im is superimposed on the current Im.

ΔIm = (Vcc−Vm−0.7) ΔR4 (Equation 1) Here, when the inverted cooling pulse COOLP-N becomes low level, the analog switch (ASW) S
Since W1 is open, the transistor Q1 is turned off, and the superimposed current ΔIm does not flow. Similarly, when the recording pulse # 1 (WRTP1-P) is at the high level, the superimposed current △ Ih1 (the superimposed current for generating the first recording high-level power Ph1, see FIGS. 1 to 4) flows, and the recording pulse # 2
When (WRTP2-P) is at a high level, the superimposed current △ Ih
2 (superimposed current for generating the second recording high-level laser power Ph2, see FIGS. 1 to 4).

FIG. 11 is a time chart showing the operation described above. Channel clock CHCLK
Signal input WTDAT indicating recording waveform synchronized with
A is stored in the data register DRA in units of 8 bits, and the content of the register DRA is stored in the next data register DA.
RB. Similarly, the data in the register DRB is
10 shows a state where the data is moved to the RC (see FIG. 9). Each time the falling edge of the fourth half-byte clock Q3 from the lower bit of the binary counter BCT (6-11 in FIG. 9) corresponds to the content of the data register DRB, the data before the half-byte clock timing is stored. D
The laser drive timing signals WRTP2-P, WRTP1-P, and COO are referred to while referring to RA and the contents of DRC indicating data after half-byte clock timing.
Generate LP-N. The above three types of laser drive timing signals WRTP2-P, WRTP1-P and COOOLP-
By inserting N into the laser drive circuit (shown in FIG. 10), a predetermined laser drive current Idl flows, and a required laser light output can be obtained.

FIG. 12 shows IP (current vs. optical output) of the semiconductor laser (31 in FIG. 10) used in the embodiment of the present invention.
It is a characteristic diagram. When the laser current is Ir milliamperes, the laser light output is Pr milliwatts. When the laser current is superimposed on Ir by △ Im milliamperes, the laser current becomes Im milliamperes, and the light output becomes Pm milliwatts, and △
When Ih 1 mA is superimposed, the laser current becomes Ih
The flow of 1 mA and the optical output is Ph1 milliwatt, and similarly, if superimposed by ΔIh2 milliamp, the laser current will flow Ih2 milliamp, indicating that the optical output will be Ph2 milliwatt.

As described above, since the information recording apparatus of the present invention has the recording waveform generating circuit capable of changing the cooling pulse width, it can easily cope with an increase in the linear velocity of the disk.
Further, information can be recorded on information recording media having various cooling rates.

Embodiment 4 FIG. 6 shows the structure of a phase change recording medium having a different cooling rate used in the present embodiment. Disk A is composed of Ag-Ge-Sb-Te recording film and A
The ZnS-SiO2 upper protective layer between the l-Ti reflective film is a thin quenched structure phase change recording medium, and the disk B is composed of an Al-Ti reflective layer and a ZnS
-A phase change recording medium having a slow cooling structure in which a Si interference layer is laminated between upper protective layers of SiO2. On the 0.6 mm thick polycarbonate substrate used for these disks, 0.7 μm grooves were formed at 1.48 μm.
It is provided spirally at the pitch. The depth of the groove is about 70 nm.

There are 24 zones for user recording in the radial direction of the disc, and 17 to 4
There are 0 sectors. As a motor control method for performing recording / reproducing, a ZCLV (Zone Constan) that changes the number of rotations of a disc for each zone in which recording / reproducing is performed.
t Lenear Velocity) method. In this format, the innermost and outermost disks in each zone have different disk linear velocities, and the innermost and outermost disk linear velocities are 6.0 m / s and 6.35 m / s, respectively. .

Information was recorded on each disk using the recording device shown in FIG. Hereinafter, the operation of the recording apparatus will be described.

Information from outside the recording apparatus is transmitted to the 8-16 modulator 8 in units of 8 bits. Disc 1
When information was recorded thereon, recording was performed using a modulation method of converting 8 bits of information into 16 bits, that is, a so-called 8-16 modulation method. In this modulation method, information having a mark length of 3T to 11T corresponding to 8-bit information is recorded on a medium. The 8-16 modulator 8 in the figure performs this modulation. Here, T represents a clock cycle at the time of information recording, and here is set to 34.2 ns.

8T: 3T converted by the modulator 8
The 11T digital signal is transferred to the recording waveform generation circuit 6, and the recording waveform shown in FIG. 14 which can reduce the circuit size of the recording waveform generation circuit 6 among the recording waveforms in FIG. 2 is generated. At this time, each power is applied to the disk A: Ph1: 12.0 mW Ph2: 12.0 mW Pm1: 4.5 mW Pm2: 0.5 mW P11: 0.5 mW P12: 0.5 mW Disk B: Ph1: 10.0 mW Ph2: 10.0 mW Pm1: 4.0 mW Pm2: 0.5 mW P11: 0.5 mW P12: 0.5 mW

The width of the high power pulse is set to about T / 2, and the cooling pulse width Tc can be changed from the outside.

The recording waveform generated by the recording waveform generating circuit 6 is transferred to a laser driving circuit 7, and the laser driving circuit 7 causes the semiconductor laser in the optical head 2 to emit light based on the recording waveform.

The optical head 2 mounted on the recording apparatus includes:
Light wavelength 650 nm as energy beam for information recording
Semiconductor laser is used. The laser light was focused on the recording film of the disk 1 by an objective lens having a lens NA of 0.6, and a laser beam having an energy corresponding to the recording waveform was applied to record information. At this time, the diameter of the laser beam is about 1
Microns and the laser beam was polarized circularly.

The present recording apparatus is compatible with a method of recording information in both grooves and lands (areas between grooves) (so-called land-groove recording method). In this recording apparatus, the tracking for the land and the groove can be arbitrarily selected by the L / G servo circuit 9.

The recorded information was reproduced using the optical head 2. By irradiating the laser beam narrowed down to the same size as at the time of recording on the recorded mark and detecting the reflected light from the mark and the part other than the mark,
Obtain a playback signal. The amplitude of the reproduced signal is amplified by the preamplifier circuit 4 and transferred to the 8-16 demodulator 10. 8
The -16 demodulator 10 converts every 16 bits into 8-bit information. With the above operation, the reproduction of the recorded mark is completed.

In order to evaluate the signal quality of the reproduced signal, the jitter of the reproduced signal was measured. At this time, recording and reproduction were performed by changing the cooling pulse width Tc from 0 to 2.4T at intervals of T / 5. At this time, Pm1 was made to slightly change in correspondence with Tc. The measured values of the above examples are shown below.

Tc disk A disk B 0.0 15.5 17.3 0.2 17.0 18.9 0.4 18.2 19.3 0.6 14.5 17.3 0.8 12.2 14.8 1.0 10.2 11.8 1.2 9.5 11.0 1.4 10.0 10.0 0.5 1.6 1.6 0.5 10.0 1.8 11.0 9.0 2.0. 0 12.0 10.3 2.2 14.5 11.8 2.4 17.5 13.3 As described above, when Tc is 1.2T for disk A, Tc is 1.8T for disk B. In the case of, the jitter value was the lowest.

Further, by setting Tc between 0.8T and 2.2T, 1 is set for both the disc A and the disc B.
A low jitter value of 5% or less is obtained, and Tc is set to 1.0T or less.
By setting it between 2.0T, a low jitter value of 12% or less can be obtained for both the disk A and the disk B. Therefore, by setting Tc to be 0.8T to 2.2T, more preferably 1.0T to 2.0T, a low jitter value can be obtained regardless of the cooling speed of the optical disk.

In terms of reducing the circuit scale of the recording waveform generating circuit, there is a great effect when Tc is an integral multiple of T / 2, such as when Tc is 1.0T, 1.5T, and 2.0T. However, especially when Tc is set to 1.0T, Pm
1 has an advantage that the power margin is widened.

Note that, even when the waveform of FIG. 3 is used as the recording waveform, by setting Tc between 0.8T and 2.2T, 15
% And a Tc of 0.9T to 1.
By setting it between 9T, a low jitter value of 10% or less was obtained for both the disk A and the disk B.
Therefore, by setting Tc to be from 0.8T to 2.2T, more preferably from 0.9T to 1.9T, a low jitter value can be obtained regardless of the cooling speed of the optical disk.

At this time, the respective powers for the disk A are as follows: Ph1: 12.0 mW Ph2: 12.0 mW Pm1: 4.5 mW Pm2: 4.5 mW Pl1: 0.5 mW Pl2: 0.5 mW Disk B , Ph1: 10.0 mW Ph2: 10.0 mW Pm1: 4.0 mW Pm2: 4.0 mW P11: 0.5 mW P12: 0.5 mW The width of the high power pulse was set to about T / 2 for each disk.

Fifth Embodiment The disc A of FIG. 6 described in the fourth embodiment is compared with the disc A of FIG.
The information was recorded using the recording device shown in FIG. Hereinafter, the operation of the recording apparatus will be described.

Information from outside the recording apparatus is transmitted to the 8-16 modulator 8 in units of 8 bits. Disc 1
When information was recorded thereon, recording was performed using a modulation method of converting 8 bits of information into 16 bits, that is, a so-called 8-16 modulation method. In this modulation method, information having a mark length of 3T to 11T corresponding to 8-bit information is recorded on a medium. The 8-16 modulator 8 in the figure performs this modulation. Here, T represents a clock cycle at the time of information recording, and here is set to 34.2 ns. The disk linear velocity was 6 m / s.

3T-1 converted by the 8-16 modulator
The 1T digital signal is transferred to the recording waveform generation circuit 6,
The recording waveform of FIG. 1 is generated. At this time, each power was set to Ph1: 12.0 mW Ph2: 12.0 mW Pm1: 4.5 mW Pm2: Variable P11: 0.5 mW P12: 0.5 mW

The width of the high power pulse was about T / 2 for each disk, and Tc was 1.5T. Also,
Pm2 can be changed from outside.

The recording waveform generated by the recording waveform generating circuit 6 is transferred to the laser driving circuit 7, and the laser driving circuit causes the semiconductor laser in the optical head 2 to emit light based on the recording waveform.

The optical head 2 mounted on the recording apparatus includes:
Light wavelength 650 nm as energy beam for information recording
Semiconductor laser is used. The laser light was focused on the recording film of the disk 1 by an objective lens having a lens NA of 0.6, and a laser beam having an energy corresponding to the recording waveform was applied to record information. At this time, the diameter of the laser beam is about 1
Microns and the laser beam was polarized circularly.

The present recording apparatus is compatible with a method of recording information on both grooves and lands (areas between grooves) (so-called land-groove recording method). In this recording apparatus, the tracking for the land and the groove can be arbitrarily selected by the L / G servo circuit 9.

The reproduction of the recorded information was also performed using the optical head 2. By irradiating the laser beam narrowed down to the same size as at the time of recording on the recorded mark and detecting the reflected light from the mark and the part other than the mark,
Obtain a playback signal. The amplitude of the reproduced signal is amplified by the preamplifier circuit 4 and transferred to the 8-16 demodulator 10. 8
The -16 demodulator 10 converts every 16 bits into 8-bit information. With the above operation, the reproduction of the recorded mark is completed.

In order to evaluate the signal quality of the reproduced signal, the jitter of the reproduced signal was measured. At this time, recording was performed while changing the intermediate power level Pm2 from 0.5 mW to 12 mW. As a result, the jitter value greatly depends on Pm2, and becomes the lowest when Pm2 is 5.0 mW.

By setting Pm2 between 3.0 and 6.5 mW, a particularly low jitter value can be obtained. By setting Pm2 between 4.5 and 5.5 mW, a low jitter value of 10% or less can be obtained. A jitter value is obtained. Therefore, Pm2 is changed to Pm
70% or more and 140% or less of 1, more preferably 100%
At least 120% or less, or Pm2 as Ph1 or 25% or more and 50% or less of Ph2, more preferably 38%
By setting the ratio to 45% or less, a high-quality reproduced signal having an extremely low jitter value can be obtained.

Embodiment 6 The disc B of FIG. 6 described in Embodiment 4 is compared with FIG.
The information was recorded using the recording device shown in FIG. Hereinafter, the operation of the recording apparatus will be described.

Information from outside the recording apparatus is transmitted to the 8-16 modulator 8 in units of 8 bits. Disc 1
When information was recorded thereon, recording was performed using a modulation method of converting 8 bits of information into 16 bits, that is, a so-called 8-16 modulation method. In this modulation method, information having a mark length of 3T to 11T corresponding to 8-bit information is recorded on a medium. The 8-16 modulator 8 in the figure performs this modulation. Here, T represents a clock cycle at the time of information recording, and here is set to 34.2 ns. The disk linear velocity was 6 m / s.

[0126] The 3T converted by the 8-16 modulator 8
The 11T digital signal is transferred to the recording waveform generation circuit 6, and the following recording waveform is generated.

The recording waveform generated by the recording waveform generating circuit 6 is transferred to the laser driving circuit 7, and the laser driving circuit causes the semiconductor laser in the optical head 2 to emit light based on the recording waveform.

The optical head 2 mounted on the recording apparatus includes:
Light wavelength 650 nm as energy beam for information recording
Semiconductor laser is used. The laser light was focused on the recording film of the disk 1 by an objective lens having a lens NA of 0.6, and a laser beam having an energy corresponding to the recording waveform was applied to record information. At this time, the diameter of the laser beam is about 1
Microns and the laser beam was polarized circularly.

The present recording apparatus is compatible with a method of recording information on both a groove and a land (a region between grooves) (a so-called land-groove recording method). In this recording apparatus, the tracking for the land and the groove can be arbitrarily selected by the L / G servo circuit 9.

Reproduction of recorded information was also performed using the optical head 2. By irradiating the laser beam narrowed down to the same size as at the time of recording on the recorded mark and detecting the reflected light from the mark and the part other than the mark,
Obtain a playback signal. The amplitude of the reproduced signal is amplified by the preamplifier circuit 4 and transferred to the 8-16 demodulator 10. 8
The -16 demodulator 10 converts every 16 bits into 8-bit information. With the above operation, the reproduction of the recorded mark is completed.

Cross erase (a phenomenon in which information recorded on an adjacent track is erased when information is recorded. Here, the adjacent track means a groove adjacent to a land or a land adjacent to a groove. In order to investigate the effect of this, measure the change in the jitter value of the reproduction signal from the land when the information is recorded in advance on the land and the information is recorded while causing a track offset in the adjacent groove. did. When recording information in adjacent grooves, information was recorded using the following three types of recording waveforms in order to compare the superiority of the recording waveform with respect to cross erase. That is, the waveform A is obtained by setting the respective powers shown in FIG. 14 as follows: Ph1: 10.0 mW Ph2: 10.0 mW Pm1: 4.0 mW Pm2: 0.5 mW P11: 0.5 mW P12: 0.5mW Waveform B is obtained by setting the respective powers shown in FIG. 3 as follows. Ph1: 10.0 mW Ph2: 10.0 mW Pm1: 4.0 mW Pm2: 4.0 mW Pl1: 0.5 mW Pl2 : 0.5 mW Waveform C is obtained by setting each power shown in FIG. 4 as follows.

Ph1: 10.0 mW Ph2: 10.0 mW Pm1: 4.0 mW Pm2: 4.0 mW P11: 0.5 mW P12: 4.0 mW For the waveforms A and B, the width of the high power pulse is set to about T
/ 2, the width of the leading pulse of the high power pulse train is 1T, and the width of the high power pulse other than the leading pulse is about T / 2. The width of the cleaning pulse Tc was 1.0 T for each waveform.

As a result of the above-described embodiment, when information is recorded in an adjacent groove by the recording waveform of the waveform C, the track offset amount starts to affect the jitter value of the reproduced signal from the land when the track offset amount is about 0.1 μm. When the amount is 0.15 μm, the jitter value increases to 15% or more. On the other hand, when information was recorded in the adjacent groove by the recording waveforms of the waveforms A and B, even if the track offset amount was 0.15 μm, there was no influence on the adjacent track. Therefore, waveforms A and B are
It can be seen that the method is extremely suitable for high-density recording where the land-groove recording method is employed or where the track pitch is equal to or smaller than the laser beam diameter.

In the above embodiment, the case where the cooling pulse width Tc is 1.0T has been described in detail.
Between 2.0T, there was a cross erase reduction effect regardless of Tc. When P12 of the waveforms A and B was varied and the measurement was performed, an effect was exhibited when P12 was equal to or less than 1/2 of Pm1, and a significant effect was obtained when P12 was equal to or less than 1/3 of Pm1. The measurement was also performed with respect to the waveform C with Pl2 being variable. However, the effect appeared when Pl2 was 1/3 of Pm1, and when P12 was 1/4 of Pm1, even when the track offset amount was 0.15 [mu] m, the effect on the adjacent track was obtained. There was no cross erase effect.

Seventh Embodiment Information is recorded on the disk B of FIG. 6 described in the fourth embodiment by using the recording device described in the sixth embodiment (FIG. 13) using the recording waveform according to the seventeenth embodiment. Was. This will be described in detail below.

Information from the outside of the recording apparatus is transmitted to the 8-16 modulator in units of 8 bits. When recording information on the disk 1, recording was performed using a modulation method for converting 8 bits of information into 16 bits, that is, a so-called 8-16 modulation method. In this modulation method, information having a mark length of 3T to 11T corresponding to 8-bit information is recorded on a medium. The 8-16 modulator in the figure performs this modulation. Here, T represents a clock cycle at the time of information recording, and here is set to 34.2 ns. The disk linear velocity was 6 m / s.

3T-1 converted by the 8-16 modulator
The 1T digital signal is transferred to the recording waveform generation circuit 6,
A recording waveform described later is generated.

The recording waveform generated by the recording waveform generating circuit is transferred to the laser driving circuit 7, and the laser driving circuit causes the semiconductor laser in the optical head 2 to emit light based on the recording waveform.

The optical head 2 mounted on the recording apparatus has
Light wavelength 650 nm as energy beam for information recording
Semiconductor laser is used. The laser light was focused on the recording film of the disk 1 by an objective lens having a lens NA of 0.6, and a laser beam having an energy corresponding to the recording waveform was applied to record information. At this time, the diameter of the laser beam is about 1
Microns and the laser beam was polarized circularly.

This recording apparatus is compatible with a method of recording information in both grooves and lands (areas between grooves) (so-called land-groove recording method). In this recording apparatus, tracking for lands and grooves can be arbitrarily selected by the L / G servo circuit.

Reproduction of recorded information was also performed using the optical head 2. By irradiating the laser beam narrowed down to the same size as at the time of recording on the recorded mark and detecting the reflected light from the mark and the part other than the mark,
Obtain a playback signal. The amplitude of the reproduced signal is increased by the preamplifier circuit 4 and transferred to the 8-16 demodulator. 8-1
The 6 demodulator converts every 16 bits into 8-bit information. With the above operation, the reproduction of the recorded mark is completed.

In order to evaluate the signal quality of the reproduced signal, FIG.
Each power level of the recording waveform shown in FIG. 5 was set as follows, information was recorded, and the jitter value of the reproduced signal was measured.

Ph: 9.0 mW Pm1: 4.0 mW Pm2: variable P11: 0.5 mW P12: 0.5 mW The recording waveform of FIG. 15 will be described in detail below. Similarly to the recording waveform described so far, in this recording waveform, the shortest mark 3T mark to the longest mark 11T mark (a 14T mark may be recorded for synchronization with a reproduction clock in some cases. The longest mark is 14T.) Marks of each length up to the high power level Ph
Is recorded by a series of continuous high power pulse trains.
At this time, recording is performed by a high power pulse train of N-1 which is one less than the number N of clocks to be recorded, such as a 3T mark as two high power pulse trains and a 4T mark as three high power pulse trains. Further, basically, the power level Pm2 (Pm2) immediately after the first high power pulse (H1) of the recording waveform and immediately before the last high power pulse (H2 to H10).
<Ph) is higher than the power level P12 between the high power pulses other than the first and last power pulses. The set value of the power level Pl1 of the cooling pulse is set equal to the set value of P12. Further, the intermediate power level Pm1 between a series of continuous high power pulse trains is defined as Ph>Pm1> Pl
2 is set.

Further, as described in the section of "Means for Solving the Problems", in this embodiment, the recording waveform for 4T in which recording is performed by using three high power pulses is shown in FIGS. Recording was performed for three types. That is, type A is the first high power pulse H
This is a recording waveform in which the power level between the first and second high power pulses H2 and the power level between H2 and the third high power pulse H3 is the level of Pm2. Type B is a recording waveform in which the power level between H1 and H2 is P12, and the power level between H2 and H3 is Pm2. Further, in the type C, the power level between H1 and H2 is Pm2, and the power level between H2 and H3 is Pl2.
This is a recording waveform having a level of 2. The cooling pulse width Tc was 1T for each waveform.

FIG. 17 shows the measurement results of the dependency of the jitter value on Pm2 for each type A, B, and C waveform. In each waveform, there is an optimum value of the jitter value with respect to Pm2, and the jitter becomes lowest when Pm2 is equal to Pm1 at 4.0 mW. In comparison between recording waveforms, the jitter value of Type C was the lowest, followed by Type B,
It is the order of type A. When the recording waveform is of type C, when Pm2 is not less than 0.5 mW and not more than 7.5 mW,
The effect of setting m2 to be not less than Pl2 appears. This means that Pm2 is greater than Pl2 and about 200% of Pm1.
The following shows that the effect of the jitter reduction appears. In addition, even in the case of type A, Pm2 is set to 0.1.
When the power is 5 mW or more and 6.8 mW or less, the effect of making Pm2 larger than P12 appears. This is Pm
2 is equal to or greater than P12 and equal to or less than 170% of Pm1, which indicates that the effect of reducing jitter appears.
Further, Pm2 is 50% of Pm1 in all the recording waveforms.
When the ratio is 170% or less, a particularly large effect is exhibited.

FIG. 18 shows the dependency of the power level Ph of the high power pulse required for recording on the Pm2 for the type C recording waveform. At this time, in each Pm2, the value of Ph at which the jitter value became the lowest is shown in the graph. The power levels other than Ph and Pm2 at this time are shown below.

Ph: variable Pm1: 4.0 mW Pm2: variable P11: 0.5 mW P12: 0.5 mW It can be seen that Ph monotonously decreases with the increase of Pm2. The same effect was obtained with the recording waveforms of types A and B. As described above, the power level immediately after the first high power pulse in the series of continuous high power pulse trains and the power level P immediately before the last high power pulse are obtained.
When m2 is higher than the power level P12 between high power pulses other than the first and last pulses, the recording sensitivity is improved,
In particular, when Pm2 is larger than P12 and 200% or less of Pm1, a good jitter value can be obtained. Further, when Pm2 is 50% or more and 170% or less of Pm1,
Particularly preferred as described above.

This recording waveform has the effect of improving the recording sensitivity while maintaining the thermal balance (including the cooling rate) between the front end and the rear end of the mark when recording the mark. This is also effective for an information recording medium having a relatively rapidly cooled medium structure, such as the disk A in FIG. 6 described in Example 4.

As described in the third embodiment, the recording waveform generating circuit 6 for generating the above-described recording waveform can change the cooling pulse width, so that it can easily cope with an increase in the disk linear velocity. In addition, information can be recorded on information recording media having various cooling rates.

FIG. 19 is a functional block diagram of the laser drive circuit (block 7 in FIG. 13). APC circuits 7-1 and 3
System drive current superimposing circuits 7-2, 7-3, 7-4, and four system DA converters (DAC) 7-5, 7-6, 7
-7 and 7-8. APC DA converter 7-5 is transmitted by data transfer from a system control bus (abbreviation: syscon bus) 5-1 of the system controller.
Is set as the output value Vr. On the other hand, by supplying the output current Ir to the semiconductor laser 31, a laser beam is generated,
When a part of the laser beam is returned to the monitoring photodiode, a monitor current Ipd flows, and the current Ipd
The voltage is converted into a voltage by the action of the pd resistor R1 and the operational amplifier OPA2 (converted voltage = −Ipd × R1) and input to the operational amplifier OPA1 via the resistor R2. Is performed, and the output current Ir is controlled so that the output voltage of the OPA 2 (which is proportional to the intensity of the laser beam) and the Vr (the target value of the laser output power) are balanced. In addition,
The loop gain of the APC circuit is determined by the ratio of the resistors R2 and R3, and the diode D1 is for preventing a superimposed current (described later) from flowing back. On the other hand, the inverted cooling pulse COOOLP-
If N is at a high level, the analog switch (AS
W) SW1 is in the closed state, and the first current superimposing DA converter 7-6 set by data transfer from the system control bus (abbreviated to syscon bus) 5-1 of the system controller (block 5 in FIG. 8). Since the output voltage Vm1 is applied to the base of the transistor Q1, the erasing power (Pm1, see FIGS. 1 to 4) superimposing current ΔIm1 shown in the following (Equation 1) is superimposed on the current Im1.

ΔIm = (Vcc−Vm1−0.7) ÷ R4 (Equation 1) Here, when the inverted cooling pulse COOLP-N becomes low level, the analog switch (ASW) S
Since W1 is open, the transistor Q1 is turned off, and the superimposed current ΔIm1 stops flowing. Similarly, when the recording pulse # 1 (WRTP1-P) is at the high level, the superimposed current ΔIh (the superimposed current for generating the high-level power Ph for recording, see FIG. 15) flows, and the recording pulse # 2 (WRTP2)
When −P) is at a high level, the superimposed current △ Im2 (the superimposed current for generating the intermediate power level laser power Pm2 immediately after the first high power pulse and immediately before the last high power pulse in a series of high power pulse trains) , See FIG. 15)
Flows.

FIG. 20 is a time chart showing the operation described above. Channel clock CHCLK
Signal input WTDAT indicating recording waveform synchronized with
A is stored in the data register DRA in units of 8 bits, and the content of the register DRA is stored in the next data register DA.
RB. Similarly, the data in the register DRB is
10 shows a state where the data is moved to the RC (see FIG. 9). Each time the falling edge of the fourth half-byte clock Q3 from the lower bit of the binary counter BCT (6-11 in FIG. 9) corresponds to the content of the data register DRB, the data before the half-byte clock timing is stored. D
The laser drive timing signals WRTP2-P, WRTP1-P, and COO are referred to while referring to RA and the contents of DRC indicating data after half-byte clock timing.
Generate LP-N. The above three types of laser drive timing signals WRTP2-P, WRTP1-P and COOOLP-
By inserting N into a laser drive circuit (shown in FIG. 19), a predetermined laser drive current Idl flows, and a required laser light output can be obtained.

As described in the third embodiment,
The semiconductor laser (3 in FIG. 19) used in the embodiment of the present invention.
The IP (current vs. light output) characteristic diagram of 1) is as shown in FIG. Also in the present embodiment, when the laser current is Ir milliamp, the laser light output is Pr milliwatt. When superimposed, the laser current flows by Ih milliamps and the optical output becomes Ph milliwatts. Similarly, when superimposed by ΔIm2 milliamps, the laser current flows by Im2 milliamps, resulting in the optical output being Pm2 milliwatts.

In the above description, Pm1 and Pm2 are set to be different from each other. However, when Pm1 and Pm2 are set to be the same, the laser drive timing signal WRTP2-P in FIG. In the above description, of the downward pulse of COOOLP-N, a portion corresponding to the timing of irradiating Pm2 may be deleted so that the current Im1 flows through the semiconductor laser 31 in FIG. In this case, the drive current superimposing circuit 7-4 and the DA converter (DAC) 7-8 become unnecessary, which is preferable because not only the laser drive circuit but also the circuit scale of the recording waveform generating circuit can be reduced.

Eighth Embodiment Information is recorded on the disk B of FIG. 6 described in the fourth embodiment by using the recording device described in the sixth embodiment (FIG. 13) using the recording waveform according to claim 21. Was. This will be described in detail below.

Information from outside the recording apparatus is transmitted to the 8-16 modulator in units of 8 bits. When recording information on the disk 1, recording was performed using a modulation method for converting 8 bits of information into 16 bits, that is, a so-called 8-16 modulation method. In this modulation method, information having a mark length of 3T to 11T corresponding to 8-bit information is recorded on a medium. The 8-16 modulator in the figure performs this modulation. Here, T represents the clock cycle at the time of information recording, and here, it is 22.8 ns. The linear velocity of the disk was set at a relatively high linear velocity of 9 m / s.

3T-1 converted by the 8-16 modulator
The 1T digital signal is transferred to the recording waveform generation circuit 6,
A recording waveform described later is generated.

The recording waveform generated by the recording waveform generating circuit is transferred to the laser driving circuit 7, and the laser driving circuit causes the semiconductor laser in the optical head 2 to emit light based on the recording waveform.

The optical head 2 mounted on the present recording apparatus includes:
Light wavelength 650 nm as energy beam for information recording
Semiconductor laser is used. The laser light was focused on the recording film of the disk 1 by an objective lens having a lens NA of 0.6, and a laser beam having an energy corresponding to the recording waveform was applied to record information. At this time, the diameter of the laser beam is about 1
Microns and the laser beam was polarized circularly.

The present recording apparatus is compatible with a method of recording information on both grooves and lands (areas between grooves) (so-called land-groove recording method). In this recording apparatus, tracking for lands and grooves can be arbitrarily selected by the L / G servo circuit.

The reproduction of the recorded information was also performed using the optical head 2. By irradiating the laser beam narrowed down to the same size as at the time of recording on the recorded mark and detecting the reflected light from the mark and the part other than the mark,
Obtain a playback signal. The amplitude of the reproduced signal is increased by the preamplifier circuit 4 and transferred to the 8-16 demodulator. 8-1
The 6 demodulator converts every 16 bits into 8-bit information. With the above operation, the reproduction of the recorded mark is completed.

In order to evaluate the signal quality of the reproduced signal, FIG.
Each power level of the recording waveform shown in FIG. 1 was set as follows, information was recorded, and the jitter value of the reproduced signal was measured.

Ph1: 9.0 mW Ph2: 9.5 mW Ph3: 10.0 mW Pm: 4.5 mW P11: 0.5 mW P12: 0.5 mW Hereinafter, the recording waveform of FIG. 21 will be described in detail. Similarly to the recording waveform described so far, in this recording waveform, the shortest mark 3T mark to the longest mark 11T mark (a 14T mark may be recorded for synchronization with a reproduction clock in some cases. The longest mark is 14T.) Marks of each length up to the high power level Ph
Recording is performed by a series of continuous high power pulse trains of 1, Ph2, and Ph3. At this time, recording is performed by a high power pulse train of N-2, which is two less than the number N of clocks to be recorded, such as a 3T mark as one high power pulse and a 4T mark as two high power pulse trains. The power level of the 3T mark recording high power pulse is Ph1, and 4T
The power level of the high power pulse train for mark recording is Ph2
The power level of the high power pulse train from 5T to 11T was Ph3. At this time, the relationship between the power levels of these high power pulses is Ph1 <Ph2 <Ph.
3 was important. Furthermore, the width of the first high power pulse and the last high power pulse of the recording waveform is basically 1T, and the width of the high power pulse other than the first and last high power pulses is 0.5T. In addition, since the recording waveform for the 3T mark, which is the shortest mark, has both the first and last high power pulses, recording was performed with a 1.5T high power pulse. Further, the width between each high power pulse was set to 0.5T. The width of the cooling pulse is 1.5T
And

The power level P of the cooling pulse
l1 to the power level Pl between each high power pulse
It was equal to the setting value of 2. Further, the intermediate power level Pm between a series of consecutive high power pulse trains is Ph1>Pm>
Pl2 was set.

As described above, the recording waveform was set, and a random signal of EFM was recorded on the information recording medium. As a result, a good jitter value of 9% or less could be obtained.
As shown in Embodiment 2, when the recording waveform of FIG. 3 was used, the power level of the high power pulse was 11.5 mW. However, by using the recording waveform described in this embodiment, the high power pulse was used. Was reduced to 10 mW.

FIG. 22 shows a change in the jitter value when the same recording was performed by changing Ph1 without changing Ph3 and setting Ph2 = (Ph1 + Ph3) / 2. The jitter value has an optimum value for Ph1 (Ph2), and Ph1 is 7.6 m corresponding to 76% of Ph3.
When the value is not less than W and is lower than Ph3, the jitter is reduced, and the effect of making Ph1 (Ph2) lower than Ph3 is exhibited. Particularly, Ph1 is 85% or more of Ph3 and 95.
%, A particularly large effect was exhibited. Also, Ph
When 1 was lower than 76% of Ph3, the jitter did not decrease. The above effects are also exhibited when Ph2 = Ph3, but as described above, Ph2 = (Ph1 +
Ph3) / 2 has a greater effect.

As described above, the width of the first and last high power pulses in the series of continuous high power pulse trains is made larger than the width of the first and last high power pulses, and at least the high power of the shortest mark is obtained. By using a recording waveform in which the power level of the pulse is set lower than the power level of the longest mark, the recording sensitivity is improved and good recording can be performed.

In addition to the method of increasing only the width of the first and last high power pulses as in the above embodiment, the width of all high power pulses is increased by a certain amount, and the width of the high power pulses is increased by the same amount. There is a method of narrowing the width between them (to increase the duty of the high power pulse). The method is applicable to all the recording waveforms shown in the present invention. As an information recording device, for example, a trailing edge of a high power pulse or a cooling pulse is delayed by a fixed amount between the recording waveform generating circuit and the laser driving circuit of FIGS. 8 and 13 described in other embodiments. What is necessary is just to mount a delay circuit.

For example, when the information recording medium is on a disk and the rotation control of the CAV method is performed, the relative speed between the energy beam and the information recording medium changes on the inner and outer circumferences of the information recording medium. In such a case, the system controller may recognize the relative speed between the energy beam and the information recording medium and transmit the information to the delay circuit so that a delay amount corresponding to the relative speed is generated. Of course, by using the above-described method of increasing the cooling pulse width in accordance with the relative speed of the energy beam and the information recording medium, for example, the relative speed becomes 12 m /
Even in the case of high-speed rotation exceeding s, recording sensitivity is improved, and good recording can be performed by using an energy beam such as a low-power semiconductor laser which is inexpensive.

[0170]

As described above in detail, the information recording method and the information recording apparatus for changing the cooling pulse width of the recording waveform at the time of information recording according to the disk linear velocity (the relative velocity between the energy beam and the information recording medium). Thereby, good recording can be performed even when the disk linear velocity changes.

Further, according to the information recording method and the information recording apparatus, the cooling pulse width of the recording waveform at the time of recording information is changed according to the cooling speed (medium structure) of the information recording medium.
Good recording can be performed on information recording media having various cooling rates.

Further, high-density recording can be achieved by an information recording method and an information recording apparatus in which a recording waveform for recording at least the shortest mark is composed of a plurality of high power pulses and the power level of the first pulse is increased.

An information recording method and an information recording method in which a recording waveform for recording at least the shortest mark is composed of a plurality of high power pulses and the power level immediately after the head pulse is higher than the power levels immediately after other high power pulses. High density recording is achieved by the recording device. Especially, the power level immediately after the first pulse is 70% or more of the intermediate power level.
The effect is great when it is 0% or less.

The recording waveform for recording at least the shortest mark is composed of a plurality of high power pulses, the power level between the high power pulses and the power level of the cooling pulse is lower than the intermediate power level, and the cooling pulse width is set to the channel. With the information recording method and the information recording device of 0.8 times or more and 2.2 times or less of the clock, good recording can be performed on information recording media having various cooling rates. In particular, when the cooling pulse width is set to 1.0 times, 1.5 times, and 2.0 times the channel clock, the circuit scale of the recording waveform generating circuit can be reduced. In particular, the cooling pulse width is set to 1.0 of the channel clock.
The case of double is more preferable because the power margin of the intermediate power is expanded.

When the information recording method and the information recording apparatus described above are used, an information recording medium having a narrow track pitch such that the track pitch becomes equal to or smaller than the recording energy beam diameter, in particular, an information recording medium corresponding to land-groove recording is used. In this case, accurate recording can be performed without erasing information of an adjacent track.

In a series of consecutive high power pulse trains, the range between the power level immediately after the first high power pulse and the power level immediately before the last high power pulse is defined as the interval between the high power pulses other than the first and last high power pulses. When it is larger than the power level and 200% or less of the intermediate power level, more preferably 50% or more and 170% of the intermediate power level
In the following cases, the recording sensitivity is improved, and a particularly large signal quality improvement effect appears.

Further, the width of the first and last high power pulses in the series of continuous high power pulse trains is made larger than the width of the first and last high power pulses, and at least
Among the high power pulses of the shortest mark, the power level of the high power pulse of the lowest power level is lower than any of the power levels of the high power pulse for recording the longest mark, and the power level of the high power pulse for recording the longest mark is high. The relative speed between the information recording medium and the recording energy beam is increased by using a recording waveform set to be 75% or more of the power level of the highest power pulse of the lowest power level among the power levels of the power pulses. if you did this,
Alternatively, even when recording is performed on an information recording medium having a structure that is easily cooled rapidly, accurate recording can be performed without lowering the recording sensitivity.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an example of a recording waveform according to the present invention.

FIG. 2 is an explanatory diagram showing an example of a recording waveform according to the present invention.

FIG. 3 is an explanatory diagram showing an example of a recording waveform according to the present invention.

FIG. 4 is an explanatory diagram showing an example of a recording waveform according to the present invention.

FIG. 5 is a diagram illustrating a relationship between a disk linear velocity and jitter according to one embodiment of the present invention.

FIG. 6 is a structural diagram of an information recording medium according to one embodiment of the present invention.

FIG. 7 is a diagram illustrating a relationship between a cooling pulse width and a jitter according to an embodiment of the present invention.

FIG. 8 is a block diagram showing an information recording apparatus according to one embodiment of the present invention.

FIG. 9 is a functional block diagram of a recording waveform generating circuit used in the embodiment of the present invention.

FIG. 10 is a functional block diagram of a laser drive circuit used in the embodiment of the present invention.

FIG. 11 is a time chart illustrating an operation state of a recording waveform generating circuit and a laser driving circuit used in the embodiment of the present invention.

FIG. 12 is an IP characteristic diagram of the semiconductor laser used in the embodiment of the present invention.

FIG. 13 is a block diagram showing an information recording apparatus according to one embodiment of the present invention.

FIG. 14 is an explanatory diagram showing an example of a recording waveform according to the present invention.

FIG. 15 is an explanatory diagram showing an example of a recording waveform according to the present invention.

FIG. 16 is an explanatory diagram showing an example of a recording waveform according to the present invention.

FIG. 17 is a diagram illustrating a relationship between Pm2 and jitter according to one embodiment of the present invention.

FIG. 18 is a diagram showing a relationship between Ph and Pm2 according to one embodiment of the present invention.

FIG. 19 is a functional block diagram of a laser drive circuit used in the embodiment of the present invention.

FIG. 20 is a time chart illustrating an operation state of a recording waveform generation circuit and a laser driving circuit used in the embodiment of the present invention.

FIG. 21 is an explanatory diagram showing an example of a recording waveform according to the present invention.

FIG. 22 shows a jitter value and Ph1 according to one embodiment of the present invention.
FIG.

[Explanation of symbols]

1: Information recording medium 2: Motor 3: Optical head 3-1: Semiconductor laser 4: Preamplifier circuit 5: System controller 5-1: Syscom bus 6: Recording waveform generation circuit 6-1: 8-bit data register DRA 6-2 : 8-bit data register DRB 6-3: 8-bit data register DRC 6-4: write pattern generation table WTGT 6-5: first 16-bit data register 6-6: second 16-bit data register 6-7: Third 16-bit data register 6-8: First 16-bit input 1-bit output data multiplexer 6-9: Second 16-bit input 1-bit output data multiplexer 6-10: Third 16-bit input 1-bit output Data multiplexer 6-11: 5-bit binary counter BCT 6-12: 8-bit shift register 7: Laser driving circuit 7-1: APC circuit 7-2: First laser driving current superimposing circuit (for @Im) 7-3: Second laser driving current superimposing circuit (for @ Ih1) 7-4: Third laser drive current superimposing circuit (for @ Ih2) 7-5: Vr designating DA converter 7-6: Vp1 designating DA converter 7-7: Vp2 designating DA converter 8: 8-16 modulator 9: L / G servo circuit 10: 8-16 demodulator Ph1: high power level Ph2: high power level Pm1: intermediate power level Pm2: intermediate power level P11: low power level P12: low power level T: reference clock for recording waveform generation Width Tc: Cooling pulse width Ph: High power level Pm: Intermediate power level.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yasushi Miyauchi 1-280 Higashi Koikekubo, Kokubunji-shi, Tokyo Inside the Central Research Laboratory, Hitachi, Ltd. (72) Inventor Akemi Hirotsune 1-280 Higashi Koigakubo Kokubunji-shi, Tokyo Inside the Central Research Laboratory (72) Inventor Jiichi Miyamoto 1-280 Higashi Koigakubo, Kokubunji-shi, Tokyo Inside the Central Research Laboratory Hitachi, Ltd. (72) Yukio Fukui 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Hitachi, Ltd. Visual Information Media Division (72) Inventor Nobuhiro Tokujuku 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Hitachi, Ltd.Video Information Media Division (72) Inventor Kuki Sugiyama 292 Yoshidacho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Address Co., Ltd. Video and Media Division, Hitachi, Ltd. (72) Inventor Hiroyuki Minemura 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside the Visual Information Media Division of Hitachi, Ltd. (72) Inventor Tetsuya Fushimi 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Video Information Media Hitachi, Ltd. Within the business division

Claims (24)

[Claims] An information recording method for recording information by irradiating a recording energy beam with at least a high power level and an intermediate power level lower than the high power level onto an information recording medium. At
After a continuous high power pulse train, recording is performed with a recording waveform having a downward pulse to a power level lower than the intermediate power level, and the width of the downward pulse is changed according to the relative speed between the energy beam and the information recording medium. An information recording method characterized in that: 2. Information recording is performed by irradiating a recording energy beam with at least a high power level and an intermediate power level lower than the high power level on an information recording medium, and recording the information. In the information recording method of performing test writing on an information recording medium prior to recording, in the test writing, after a continuous high power pulse train, a recording waveform having a downward pulse to a power level lower than the intermediate power level is used. An information recording method comprising performing recording and changing the width of the downward pulse. 3. An information recording medium is irradiated with an energy beam for recording at least at a high power level and at an intermediate power level lower than the high power level, thereby recording marks having a plurality of lengths. In the information recording method of forming and recording information, at least the shortest mark is recorded using a continuous high power pulse train,
An information recording method, wherein the power level of the first pulse is higher than the power level of the last high power pulse. 4. An information recording medium is irradiated with an energy beam for recording at least at a high power level and at an intermediate power level lower than the high power level to irradiate a recording mark having a plurality of lengths. In the information recording method of forming and recording information, at least the shortest mark is recorded using a continuous high power pulse train, and the power level immediately after the first pulse is equal to or higher than the power level immediately after the high power pulse other than the first pulse. An information recording method characterized in that: 5. An information recording apparatus for recording information by irradiating a recording energy beam with at least a high power level and an intermediate power level lower than the high power level onto an information recording medium. At
After a continuous high power pulse train, a recording waveform having a downward pulse to a power level lower than the intermediate power level is generated, and the width of the downward pulse is changed according to the relative speed between the energy beam and the information recording medium. An information recording device comprising a waveform generating means. 6. Information recording is performed by irradiating a recording energy beam with at least a high power level and an intermediate power level lower than the high power level onto an information recording medium, thereby recording information. In an information recording apparatus for performing test writing on an information recording medium prior to recording, in the test writing, a recording waveform having a downward pulse to a power level lower than an intermediate power level after a continuous high power pulse train. An information recording apparatus comprising: a recording waveform generating means for generating and changing the width of the downward pulse. 7. An information recording medium is irradiated with an energy beam for recording at least at a high power level and at an intermediate power level lower than the high power level so that recording marks of a plurality of lengths are formed. In the information recording apparatus for recording information by forming, at least at the time of the shortest mark recording, a recording waveform generating means for generating a continuous high power pulse train and making the power level of the first pulse larger than the power level of the last pulse. An information recording device, characterized in that: 8. An information recording medium is irradiated with an energy beam for recording at least at a high power level and at an intermediate power level lower than the high power level to irradiate a recording mark having a plurality of lengths. In the information recording apparatus for recording and recording information, at least at the time of the shortest mark recording, a continuous high power pulse train is generated, and the power level immediately after the first pulse is set to be equal to or higher than the power level immediately after the high power pulse other than the first pulse. An information recording apparatus, comprising: a recording waveform generating unit that performs the recording. 9. An information recording method for recording information by irradiating a recording energy beam with at least a high power level and an intermediate power level lower than the high power level onto an information recording medium. At
During each high power pulse of the continuous high power pulse train and after the continuous high power pulse train, recording is performed with a recording waveform having a downward pulse to a power level lower than the intermediate power level, and after the continuous high power pulse train. The width of the downward pulse to 0.8 of the channel clock.
An information recording method characterized by being at least twice and not more than 2.2 times. 10. An information recording method in which information is recorded by irradiating an information recording medium with a recording energy beam at least at a high power level and an intermediate power level lower than the high power level. In each of the successive high power pulse trains, and after the continuous high power pulse train, recording is performed with a recording waveform having a downward pulse to a power level lower than the intermediate power level, and a continuous high power pulse train is performed. An information recording apparatus, comprising: a recording waveform generating means for setting the width of a downward pulse after 0.8 to 0.8 times or more and 2.2 times or less of a channel clock. 11. The information recording method according to claim 9, wherein the width of the downward pulse after the continuous high power pulse train is set to an integral multiple of 1/2 of the channel clock. Recording method. 12. An information recording apparatus according to claim 10, further comprising a recording waveform generating means for setting the width of a downward pulse after a continuous high power pulse train to an integral multiple of 1/2 the channel clock. An information recording device, characterized in that: 13. The information recording method according to claim 4, wherein a power level immediately after the first pulse is 70% to 140% of the intermediate power level. 14. An information recording apparatus according to claim 8, further comprising a recording waveform generating means having a power level immediately after the head pulse of 70% to 140% of said intermediate power level. Recording device. 15. An information recording method according to claim 1, wherein information is recorded on both lands and grooves on said information recording medium. Characterized information recording method. 16. A method according to claim 5, wherein the first and second aspects are different from each other.
The information recording apparatus according to any one of the above, further comprising tracking servo means for recording information on both lands and grooves on the information recording medium. 17. A recording mark having a plurality of lengths is formed by irradiating an information recording medium with a recording energy beam at least at a high power level and an intermediate power level lower than the high power level. In an information recording method for recording information, at least the longest mark is recorded using a continuous high power pulse, and a power level immediately after a head high power pulse and a tail end of a series of continuous high power pulse trains. The power level immediately before the high power pulse is higher than the power level between other high power pulses. 18. The information recording method according to claim 17, wherein, in a series of continuous high power pulse trains, the power level immediately after the first high power pulse and the power level immediately before the last high power pulse are different from each other. And a power level greater than the power level between the high power pulses other than the last power pulse and 200% or less of the intermediate power level. 19. The information recording method according to claim 18, wherein the shortest mark is recorded by two high power pulses.
The second shortest mark is recorded by three high power pulses, the third shortest mark is recorded by four high power pulses, and the power level between the first and second high power pulses when the shortest mark is recorded. The power level between the first and second high power pulses during the recording of the second shortest mark, between the first and second high power pulses during the recording of the third shortest mark, and between the third and fourth high power pulses. The power level during the third high power pulse is 5 of the intermediate power level.
An information recording method characterized by being 0% or more and 170% or less. 20. The information recording method according to claim 19, wherein the power level between the second and third high power pulses at the time of recording the second shortest mark and the power level at the time of recording the third shortest mark are recorded. An information recording method, wherein a power level between the second and third high power pulses is 50% or less of the intermediate power level. 21. A recording mark having a plurality of lengths is formed by irradiating a recording energy beam with at least a high power level and an intermediate power level lower than the high power level onto an information recording medium. In an information recording apparatus for recording information, at least, the power level of the high power pulse for recording the shortest mark is lower than the power level of the high power pulse for recording the longest mark. Information recording method. 22. The information recording method according to claim 21, wherein at least the power level of the high power pulse having the lowest power level among the high power pulses for recording the shortest mark records the longest mark. The power level of the high power pulse for recording the longest mark is lower than any of the power levels of the high power pulse, and is at least 75% of the power level of the high power pulse of the lowest power level. Characterized information recording method. 23. A recording mark having a plurality of lengths is formed by irradiating a recording energy beam with at least a high power level and an intermediate power level lower than the high power level onto an information recording medium. 23. An information recording apparatus for recording information, comprising:
An information recording apparatus characterized by comprising a recording waveform generating means for generating at least one of the recording waveforms according to the information recording method described in (1). 24. An information recording medium is irradiated with a beam having energy to form a mark having a plurality of lengths,
In the information recording method for recording information, when recording one of the marks, the energy beam is irradiated as a pulse train, and the falling level of the pulse train closest to the head of the mark is the next pulse train. The information recording method is set to be higher than the falling level of the information.