JPH11120563A - Recording compensation method for optical disk and optical disk recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recording compensation method for an optical disk and an optical disk recorder performing overwrite operation in a recording medium as it is of a GeSbTe system used in a DVD-RAM even in a large capacity, high density phase transition type optical disk realized by a high numerical aperture of an objective lens, or a short wavelength of a light source. SOLUTION: In the optical disk recorder making a function F=LV.NA /(λ.BL) shown by a linear velocity (LV:m/sec) of a storage medium, an objective lens numerical aperture of an optical head (NA), a wavelength of recording laser light (λ:μm) and a signal bit length (BL:μm) F >=20, and recording information on an information rewritable optical disk using a phase transition type storage medium, an irradiation pulse in recording is made a multi-pulse consisting of at least three levels, and a light emission pulse of a final end is set in a time width longer than any other irradiation pulses, and the recording compensation for the optical disk using the information rewritable phase transition type recording medium is performed by the light emission control of the recording laser light.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for compensating recording of an information rewritable optical disk using a phase change recording medium and an optical disk recording apparatus.

[0002]

2. Description of the Related Art A DVD-RAM is a typical example of an information rewritable optical disk using a phase change recording medium. In a DVD-RAM, EFM (Eight-to-Fourteen Modulation) modulation is used as a signal modulation method, and a recording waveform is generated by multiplying a light emission pulse of a semiconductor laser for each of 3T to 11T marks. . FIG. 9 shows an example of a recording waveform in a DVD-RAM. As shown in FIG. 9, the 3T mark is recorded by a single light-emitting pulse, and the 11T mark is recorded by nine multi-pulses. Immediately after each pulse, a portion of Bias Power2 set to a value lower than Bias Power1 corresponding to the erasing power is provided to control the crystallization speed of the phase change recording medium.
Further, both the first pulse and the last pulse have a length of about 1T, and each irradiation start position is configured to be delayed by a fixed amount (T _SFP , T _{SLP in} FIG. 9) with respect to the clock.

[0003]

As a technique for realizing a large-capacity, high-density phase-change type optical disk exceeding DVD-RAM, a method for reducing the spot size is known. The spot size on the recording medium is approximately λ / N
A, a method using a short wavelength semiconductor laser light source such as GaN or ZnSe, a solid immersion method,
A numerical aperture (NA: Numerical) of an objective lens is provided by a two-group lens represented by a lens (SIL: Solid Immersion Lens).
Aperture) can be reduced by increasing the size.

For example, λ = 640 nm, NA = 0.85
Then the spot diameter is about 0.75 μm on the medium
For example, when a signal is recorded and reproduced using (1,7) modulation, a recording linear density of about 0.21 μm / bit can be achieved. FIG. 10 shows a comparison result between the spot shape in this case and the spot shape in the DVD-RAM.

Here, in the (1, 7) modulation, data having a basic data length of m bits is converted into a variable length code (d, k ;,
m, n; r), for example, a code that restricts the minimum run d of 0 of the channel bit string of the RLL (1, 7) code from continuing for a predetermined number of times for data having a basic data length m of 2 bits. Is a conversion table including a minimum run d of 0 as 1 bit, a maximum run k of 0 as 7 bits, a basic data length m of 2 bits, a basic code length n of 3 bits, and a maximum constraint length r of 3 as a variable length. It is converted to a code (1,7; 2,3; 3). For the (1, 7) modulation, for example, the following conversion table is used.

[0006] FIG. 11 shows the temperature distribution (calculated value) on the medium when the 8T mark on the DVD-RAM is recorded by each spot. The same linear velocity condition is used for comparison. From these results, it can be seen that when high-density recording is performed using a high numerical aperture objective lens, the rate of temperature rise and cooling is higher than that of a conventional DVD-RAM. This is equivalent to the case where the channel clock of the recording signal is increased in order to improve the transfer rate, and the media linear velocity is increased in proportion thereto. The same applies to a case where the wavelength of a semiconductor laser as a light source is shortened. When overwriting is realized in the phase change recording, it is desirable that there is no difference in the heating / cooling rate between the portion where the recording mark is written (amorphous state) and the portion where the recording mark is not written (crystal state). However, when such an essentially steep temperature rising / cooling rate characteristic is exhibited, the heat absorption rate between the amorphous state and the crystalline state is reduced by the recording pulse of the DVD-RAM which is assumed to be used at a relatively low linear velocity. The difference cannot be completely corrected by the recording compensation, and the trailing edge of the mark is generated at different positions in both cases. Since this effect is observed as a constant displacement on the recording medium, the effect increases as the recording density increases.

When these elements are taken into consideration and converted into a function, the linear velocity (LV: m / sec) of the recording medium, the numerical aperture (NA) of the objective lens of the optical head, and the wavelength (λ: μ) of the recording laser beam
m) and the following function F represented by the signal bit length (BL: μm).

F = LV · NA / (λ · BL) The value of the above function F increases as the spot size decreases, the linear velocity increases, and the recording density increases. By the way, the transfer rate is 30M which is equivalent to DVD
Assuming bps, the value of F in this case is about 27
And greatly exceeds the value 13 in the DVD-RAM.

Thus, the numerical aperture of the objective lens (NA: Nu
When the spot size is reduced by increasing the merical aperture, the temperature at the center of the spot increases, and the time required for the temperature to rise and fall decreases. In addition, in order to extend the life of the recording medium, a measure is generally taken to improve heat dissipation by, for example, increasing the thickness of the aluminum reflective film. That is, by increasing the recording density, the recording medium has a quenching structure, and it becomes difficult to overwrite the recording medium with the conventional recording compensation pulse.

In order to solve this problem, the crystallization speed may be controlled by, for example, recording compensation for enabling heat storage.

Accordingly, an object of the present invention is to provide a large-capacity, high-density phase-change optical disk realized by increasing the numerical aperture of an objective lens or shortening the wavelength of a light source in view of the above-mentioned conventional situation. Another object of the present invention is to provide an optical disk recording compensation method and an optical disk recording apparatus that enable an overwrite operation with a GeSbTe-based recording medium used in a DVD-RAM.

[0012]

According to the present invention, a linear velocity (LV: m / sec) of a recording medium, an objective lens numerical aperture (NA) of an optical head, a wavelength of a recording laser beam (λ: μm), and Information is recorded on a rewritable optical disk of information using a phase change recording medium, with a function F F = LV · NA / (λ · BL) represented by a signal bit length (BL: μm) being F ≧ 20. A recording compensation method for an optical disc in an optical disc recording apparatus, wherein an irradiation pulse at the time of recording is a multi-pulse having at least three levels, and an emission pulse at the end is set to a longer time width than any other irradiation pulse. Recording compensation for an optical disk using a rewritable phase-change recording medium is performed by controlling the emission of a recording laser beam.

In the optical disk recording compensation method according to the present invention, for example, immediately after irradiating the last emission pulse, the erasing power level is set immediately.

In the recording compensation method for an optical disk according to the present invention, for example, the irradiation start position and the emission pulse width of the first emission pulse, and the emission start position and the emission pulse width of the last emission pulse are set as Depending on the recording mark length, it may be set arbitrarily.Furthermore, even in the pulse train section other than the first and last emission pulses,
The light emission pulse width may be set arbitrarily.

Further, in the recording compensation method for an optical disk according to the present invention, for example, the recording mark is NT (N: integer,
T: the channel clock width), the number of irradiated multi-pulses is N-1.

According to the present invention, the linear velocity (LV: m / s)
ec), a function FF expressed by the objective lens numerical aperture (NA) of the optical head, the wavelength of the recording laser light (λ: μm), and the signal bit length (BL: μm) BL) is set to F ≧ 20, an optical disk recording apparatus for recording information on an information rewritable optical disk using a phase-change recording medium, wherein the laser light source for emitting the recording laser light is used for recording. It is characterized by comprising a light emission control means for performing light emission control in which the irradiation pulse is a multi-pulse consisting of at least three levels and the last light emission pulse is set to a longer time width than any other irradiation pulse.

In the optical disk recording apparatus according to the present invention, for example, the light emission control means controls the light emission of the laser light source so as to set the erase power level immediately after the irradiation of the last light emission pulse.

In the optical disk recording apparatus according to the present invention, the light emission control means determines the irradiation start position of the first light emission pulse and the light emission pulse width, and the irradiation start position of the last light emission pulse and the light emission pulse width, respectively. Any setting may be made according to the recording mark length. Further, the light emission control means may be capable of arbitrarily setting the light emission pulse width in a pulse train section other than the first and last light emission pulses.

Further, in the optical disk recording apparatus according to the present invention, the light emission control means may include, for example, when the recording mark is NT (N: integer, T: channel clock width).
The light emission control of the laser light source is performed so that the number of multi-pulses to be irradiated is N-1.

[0020]

Embodiments of the present invention will be described below in detail with reference to the drawings.

The present invention is applied to, for example, a rewritable phase-change optical disk recording / reproducing apparatus using a high numerical aperture two-group objective lens.

This phase-change type optical disk recording / reproducing apparatus includes an optical head 10 having a structure as shown in FIG. 1, and records information on the optical disk 1 while rotating the optical disk 1 at a constant angular velocity by a spindle motor 2 for example. The surface is scanned with laser light by the optical head 10 and (1,
7) Information is recorded / reproduced optically by modulation.

The optical head 10 includes a semiconductor laser (LD) 3 as a light source that emits a recording / reproducing laser beam for irradiating the optical disc 1. The emitted light from the semiconductor laser 3 is converted into parallel light by a collimator lens 4, passes through a diffraction grating 5 for generating a side spot, and then passes through a beam splitter 6 and a 波長 wavelength plate 7 to form an aspherical two-group objective. The light enters the lens unit 20 and is focused on the information recording surface of the optical disc 1 by the aspherical two-group objective lens unit 20. Part of the light emitted from the semiconductor laser 3 is reflected by the beam splitter 6 and
Is led to the light emission power monitor detector 9 through
It is used for automatic light control (APC: Automatic Power Control) for controlling laser power on an information recording surface. Light reflected from the optical disc 1 (ie, a reproduction signal) is reflected by the beam splitter 6 and guided to a detection optical path, and a part of the light is reflected by the beam splitter 11 and is condensed.
The light enters the servo signal detector 14 via the second lens 2 and the cylindrical lens 13 and is photoelectrically converted. The remaining light enters the RF signal detector 17 via the lenses 15 and 16 and is photoelectrically converted. In the optical head 10, a focus error signal is generated using an astigmatism method,
Further, a tracking error signal is generated by using a differential push-pull method. Here, the servo error signal and the reproduction RF signal are detected by the two signal detection detectors 14 and 17, but it is also possible to cover them with one detector.

The above-mentioned aspherical two-group objective lens unit 20
Is, for example, as shown in FIG. 2, a first electromagnetic actuator 22 for driving a first lens 21 and a second lens 2
3 for driving the second actuator 3. Second
The lens 23 is mounted on a second electromagnetic actuator 24 movable in the optical axis direction and the track direction, and has a numerical aperture of about 0.5. Also, the first lens 21
Above the second lens 23, it is mounted on a first electromagnetic actuator 22 different from the second electromagnetic actuator 24, and is configured to be controllable at an arbitrary position on the optical axis.

The first lens 21 moves together with the second lens 23 in the track direction and follows the tracking servo. Then, the light beam from the semiconductor laser 3 passes through these two objective lenses 23 and 21 and is condensed on the phase-change information recording surface of the optical disc 1. At this time, the effective objective lens numerical aperture of the second group lenses 23 and 21 is about 0.85.

Here, as the numerical aperture of the objective lens increases, the skew tolerance of the optical disk recording / reproducing apparatus generally decreases. Denoting the wavefront aberration due to disc skew (X direction) by a polynomial of Seidel W (x, y) = W 22 x 2 + W 31 x (x 2 + y 2) + W 51 x
(X ² + y ² ) ² . Here W ₂₂ astigmatism, W ₃₁ is the third-order coma aberration, W ₅₁ is the fifth-order coma aberration. Of these, the dominant third-order coma aberration W ₃₁ is given by the following equation, where n is the refractive index of the disk substrate. When the skew angle θ is as small as 1 degree or less, the numerical aperture NA is approximately 3 It is proportional to the power and the disk substrate thickness t.

W ₃₁ = (n ² -1) n ² sin θ cos θ / 2 (n
²⁻ sin ² θ) ^2/5 · tNA ³ / λ Therefore, in an optical disk recording / reproducing apparatus using an aspherical second lens unit and increasing the numerical aperture to 0.85, the skew is equivalent to that of a DVD-RAM. In order to ensure the tolerance, it is necessary to reduce the thickness of the substrate to about 0.1 mm.

On the other hand, when a phase-change recording medium is formed on a disk substrate, the first dielectric film (ZnS-Si
O ₂ ), recording film (Ge ₂ Sb ₂ Te ₅ ), second dielectric film (Z
nS-SiO ₂ ) and an aluminum alloy reflective film are formed in this order, and a preformat such as an address or a sector mark is embossed on a substrate having a thickness of 0.1 mm.
Since it is difficult to form a film in accordance with the above-described procedure, the optical disk 1 used in this optical disk recording / reproducing apparatus is formed on a preformatted disk substrate 1A having a thickness of 1.2 mm as shown in FIG. Contrary to usual, the aluminum alloy reflection film 1B and the second dielectric film (ZnS-Si
O ₂ ) 1C, recording film (Ge ₂ Sb ₂ Te ₅ ) 1 D, and first dielectric film (ZnS—SiO ₂ ) 1 E
Finally, a disk protective film 1F having a thickness of 0.1 mm is added.

In the phase change type optical disk recording / reproducing apparatus according to this embodiment, the semiconductor laser 3 of the optical head 10 is driven by a semiconductor laser driving circuit 30 having a structure as shown in FIG. The information recording is performed by controlling the recording power of the value and emitting a multi-pulse corresponding to each recording mark. Also,
For the (1,7) modulation mark length of 2T to 8T, a multi-pulse composed of 1 to 7 emission pulses is created and recorded. That is, as shown in FIG.
An N-1 emission pulse train is generated for a recording mark of NT (N: an integer from 2 to 8, T: channel clock width). Compared to the N-2 light emission pulse in the DVD-RAM, there is an effect of lowering the peak value of the irradiation power, thereby improving the durability (number of overwrites) of the phase change recording medium.

The semiconductor laser drive circuit 30 shown in FIG.
Are three current sources 3 for supplying a drive current to the semiconductor laser 3.
, 32, 33, and three types of recording signals Data1,
The operation of each of the current sources 31, 32, and 33 is selectively controlled in accordance with Data2, Data3, and the corresponding LD current control signals LDC1, LDC2, and LDC3, so that the emission waveform of the semiconductor laser 3 is formed. It has become. That is, the LD current control signal LDC1 is used as the reproduction power (Read Pow in FIG.
er) and erasing power during recording (B in FIG. 5).
ias Power1), which is a signal indicating the first
Of the current source 31 is controlled. Further, the LD current control signal LDC2 is a cooling power during recording (Bi in FIG. 5).
as Power2), which controls the operation of the second current source 32. Further, the LD current control signal LDC3 has a peak power during recording (P in FIG. 5).
eakPower), which controls the operation of the semiconductor laser 3 from the third current source 33. The light emission pulses generated by the drive currents from the current sources 31, 32, and 33 correspond to the three types of recording signals Data1 and Dat.
a2 and Data3.

The above three types of recording signals Data1, Data1
Data2 and Data3 are generated by the recording pulse generation circuit 40 having the configuration shown in FIG. 6 by the following method, and supplied to the semiconductor laser drive circuit 30.

The recording pulse generating circuit 40 shown in FIG.
Indicates that the recording data is NRZI (No Return to Zero Invers)
e) A pattern detection circuit 41 input as a signal is provided, and the pattern detection circuit 41 detects a pattern in synchronization with a channel clock, thereby determining a recording mark length.

In this embodiment, N-1 pulses are generated. For example, when 2T is detected, only the first pulse is generated, and when 3T is detected, the first pulse and the last pulse are generated. What is necessary is just to generate two pulses. 4T
In the above case, a pulse train is inserted between the first pulse and the last pulse. Also, during each light emission pulse, a power lower than the erasing power level (Bias Power)
The output is reduced until r2).

The result of the judgment by the pattern detection circuit 41 is given to a recording signal generation circuit 42, and based on the result of the judgment, each of the recording signals Data1, Data2, Data
3 is generated.

The first recording signal Data1 is "HIGH" during reproduction, "LOW" in a multi-pulse light emission portion,
Otherwise, it is a logic signal that becomes “HIGH”.
The second recording Data2 is the first recording signal Dat
a1 is an inverted signal. Third recording signal Data
Reference numeral 3 denotes a peak pulse, which includes the above-described head pulse, end pulse, and pulse train.

That is, the recording signal generation circuit 42 outputs the first and second recording signals Data1 and Data2 in accordance with the pattern detected by the pattern detection circuit 41, as well as the first pulse Enable signal and the pulse train Enable. Signal, terminal pulse Enable
Output signals and clock signals.

The first and second recording signals Data1 and Data2 obtained by the recording signal generating circuit 42 are given an arbitrary delay amount by the variable delay elements 43 and 44, respectively, and supplied to the semiconductor laser driving circuit 30. Is done.

The first pulse, the pulse train, and the last pulse constituting the third recording signal Data3 are generated as follows.

That is, the leading pulse is generated in the D flip-flop 45 by the leading pulse Enable signal and the clock signal of the output of the recording signal generating circuit 42. The leading pulse Enable signal is given an arbitrary delay amount by the variable delay element 46, and is also used as a clear signal of the leading pulse. The pulse width of the leading pulse is set by changing the delay amount of the variable delay element 46 according to the detected mark length.
The leading pulse generated by the D flip-flop 45 is sent to the OR circuit 48 via the variable delay element 47 so that the light emission start position can be set to an arbitrary position with respect to the channel clock in accordance with the mark length. Is output.

The pulse train is generated in the D flip-flop 49 by the pulse train Enable signal and the clock signal out of the output of the recording signal generation circuit 42, and is output to the OR circuit 48. The clock signal is given an arbitrary delay amount by the variable delay element 50, and is also used as a pulse train clear signal. The pulse width of the pulse train can be freely changed by the clear signal.

Further, the terminal pulse is generated in the D flip-flop 51 by the terminal pulse Enable signal and the clock signal of the output of the recording signal generation circuit 42. The termination pulse Enable signal is given an arbitrary delay amount by the variable delay element 52, and is also used as a termination pulse clear signal. The pulse width of the end pulse is set by changing the delay amount of the variable delay element 52 according to the detected mark length. Then, the terminal pulse generated in the D flip-flop 51 is set so that the light emission start position can be set to an arbitrary position with respect to the channel clock according to the mark length.
The signal is output to the OR circuit 48 via the variable delay element 53.

The OR circuit 48 outputs a third recording signal Data3 by combining these three signals by a logical OR.

The first to third recording signals Data1, Da
In order to synchronize ta2 and Data3, the first recording signal Data1 and the second recording signal Data2 are also output via the variable delay elements 43 and 44.

FIG. 5 shows the above three types of signal waveforms. In FIG. 5, 2T _LPS , 3T _LPS , and 8T _LPS are the start pulse irradiation start positions (delay amounts from the channel clock) at each mark length, 2T _LPW , 3T _LPW , and 8T _LPW are also the top pulse width, and T _PTW is the pulse train. Width, 3T
_TPS and 8T _TPS represent the end pulse irradiation start position (delay from the channel clock in the ± direction) at each mark length, and 3T _TPW and 8T _TPW similarly represent the end pulse width.

As described above, in the phase change type optical disk recording / reproducing apparatus in this embodiment, the end pulse width is set longer than the pulse widths of the head pulse and the pulse train. After the end pulse irradiation,
Return to Power1 (erasing power level). Thus, it is possible to prevent the trailing edge of the recording mark from being shifted at the time of overwriting between the amorphous portion and the crystalline portion.

On the phase change type optical disc 1 shown in FIG. 3, the conditions are as follows: wavelength = 640 nm, NA = 0.85, channel clock = 40 MHz, linear velocity = 5.6 m / s (recording linear density is 0.21 μm / bit). FIG. 7 shows the difference (calculation result) in the temperature change on the recording medium between the recording compensation in the DVD-RAM and the recording compensation in the present invention when the (1,7) modulation 5T mark is recorded. Shown in From this calculation result, by using the recording compensation method according to the present invention, even when the beam spot becomes small and the temperature-increasing cooling rate essentially increases, it is possible to store heat and correct the crystallization rate. That is, according to the method of the present invention, even when the numerical aperture of the objective lens is large or the wavelength of the semiconductor laser light source is shortened, overwriting on the phase change recording medium is possible. Further, by appropriately changing the irradiation pulse width of the multi-pulse and the irradiation start position according to each recording mark from 2T to 8T, it becomes easy to accurately control the rising and falling edges, In high-density recording / reproduction, an improvement in the reproduction signal jitter value can be realized.

Further, in order to compare the recording compensation in the DVD-RAM with the recording compensation in the present invention, the linear velocity (LV) = 2.8 m / s and the linear velocity (LV) = 4.2 m /
At three linear velocities of s and linear velocity (LV) = 5.6 m / s, the overwrite characteristics of the phase change optical disk were measured as follows.

That is, the signal format in the DVD-RAM is EFM-plus, but for comparison with the present invention, measurement was performed using (1,7) modulation. That is, when the recording mark is NT, a total of N-1 multi-pulses are irradiated, and in the case of the DVD-RAM method, after the terminal pulse is irradiated, the power is changed to Bias Power2 for a fixed time and then changed to Bias Power1 which is the erasing power. In this way, the recording compensation conforms to the DVD-RAM method shown in FIG. 9. In the present invention, the recording compensation is performed by immediately changing to the Bias Power 1 after the irradiation of the terminal pulse. In each case, wavelength (λ) = 640
The conditions of nm, the numerical aperture of the objective lens (NA) = 0.85, and the recording linear density (BL) = 0.21 μm / bit are common. The value of F obtained by substituting these values into F = LV · NA / (λ · BL) is 17.7,
The values were 26.6 and 35.4, and the reproduction jitter value after 10 times of overwriting when recording and reproducing the (1, 7) modulated signal under each condition was measured. FIG. 8 shows the measurement results. As is apparent from the measurement results, in the recording compensation according to the present invention, the jitter value at the time of overwriting is reduced as compared with the recording compensation method of the DVD-RAM, particularly in a region where the value of F exceeds 20. The effect is obtained.

[0049]

As described above, according to the present invention, a DVD-RAM can be used even in a large-capacity, high-density phase-change optical disk realized by increasing the numerical aperture of an objective lens or shortening the wavelength of a light source. The overwrite operation can be performed with the GeSbTe-based recording medium used in the above. The present invention is also effective for improving the transfer rate of a phase change optical disk recording device. On the other hand, N-1
The use of the recording compensation of the system has an effect of reducing the input power to the recording medium, and this has a function of extending the life (Cyclability) of the phase change type optical disc. Furthermore,
By changing the multipulse according to the recording mark,
It is easy to accurately control the rising and falling edges, and it is possible to improve the reproduction signal jitter value in high-density recording and reproduction.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a configuration of an optical head in a phase change optical disk recording / reproducing apparatus to which the present invention is applied.

FIG. 2 is a sectional view of a principal part schematically showing a structure of an aspherical two-group objective lens unit provided in the optical head.

FIG. 3 is a main part view schematically showing a structure of an optical disk used in the optical disk recording / reproducing apparatus.

FIG. 4 is a circuit diagram showing a configuration of a semiconductor laser drive circuit in the phase change optical disk recording / reproducing apparatus.

FIG. 5 is a waveform diagram for explaining a recording compensation operation in the phase change optical disk recording / reproducing apparatus.

FIG. 6 is a circuit diagram showing a configuration of a recording pulse generating circuit in the phase change type optical disk recording / reproducing apparatus.

FIG. 7 is a characteristic diagram showing a difference (calculation result) in a temperature change on a recording medium between recording compensation in a DVD-RAM and recording compensation in the present invention.

FIG. 8 is a diagram showing results of measuring overwrite characteristics of a phase-change optical disc at three types of linear velocities in order to compare recording compensation in a DVD-RAM with recording compensation in the present invention.

FIG. 9 is a waveform chart showing an example of a recording waveform in a DVD-RAM.

FIG. 10 is a characteristic diagram showing light intensity characteristics of each objective lens with NA = 0.85 and NA = 0.6.

FIG. 11 is a characteristic diagram showing a temperature distribution (calculated value) on a medium when each objective lens with NA = 0.85 and NA = 0.6 is used.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 optical disk, 3 semiconductor laser, 10 optical head, 20 aspherical two-group objective lens unit, 30 semiconductor laser drive circuit, 40 recording pulse generation circuit

Claims (10)

[Claims] A linear velocity (LV: m / sec) of a recording medium;
The objective lens numerical aperture (NA) of the optical head, the wavelength (λ: μm) of the recording laser beam, and the signal bit length (BL: μ)
m), the function FF = LV · NA / (λ · BL) represented by F) is set to F ≧ 20, and the optical disc recording device records information on the rewritable optical disc using the phase change recording medium. A recording compensation method, in which an irradiation pulse at the time of recording is a multi-pulse consisting of at least three levels, and an emission pulse at the end is set to have a longer time width than any other irradiation pulse, and a phase change in which information can be rewritten. A recording compensation method for an optical disc, comprising performing recording compensation on an optical disc using a type recording medium by controlling light emission of a recording laser beam. 2. The erasing power level is set immediately after the last emission pulse is irradiated.
The recording compensation method for an optical disc according to the above. 3. The irradiation start position and the emission pulse width of the first emission pulse and the emission start position and the emission pulse width of the last emission pulse can be arbitrarily set according to each recording mark length. 2. The recording compensation method for an optical disk according to claim 1, wherein: 4. The recording compensation method for an optical disk according to claim 3, wherein the light emission pulse width can be arbitrarily set in a pulse train section other than the first and last light emission pulses. 5. The recording compensation of an optical disc according to claim 1, wherein when the recording mark is NT (N: integer, T: channel clock width), the number of irradiated multi-pulses is N-1. Method. 6. A linear velocity (LV: m / sec) of a recording medium,
The objective lens numerical aperture (NA) of the optical head, the wavelength (λ: μm) of the recording laser beam, and the signal bit length (BL: μ)
An optical disc recording apparatus for recording information on an information rewritable optical disc using a phase-change recording medium, wherein a function FF = LV · NA / (λ · BL) represented by m) is set to F ≧ 20. An emission control in which an irradiation pulse at the time of recording is set to a multi-pulse of at least three levels with respect to the laser light source that emits the recording laser light, and the last emission pulse is set to have a longer time width than any other irradiation pulse. Optical disc recording apparatus comprising light emission control means for performing 7. The light emission control means controls the light emission of the laser light source so as to set the erase power level immediately after the emission of the last light emission pulse.
An optical disc recording apparatus according to claim 1. 8. The light emission control means sets the irradiation start position and the light emission pulse width of the first light emission pulse, and the irradiation start position and the light emission pulse width of the last light emission pulse according to each recording mark length. 8. The optical disk recording apparatus according to claim 7, wherein the setting can be arbitrarily set. 9. The optical disk recording apparatus according to claim 6, wherein said light emission control means can arbitrarily set a light emission pulse width in a pulse train section other than the first and last light emission pulses. 10. The light emission control means, wherein the recording mark is N
7. The optical disk recording according to claim 6, wherein at T (N: integer, T: channel clock width), the emission control of the laser light source is performed so that the number of multi-pulses to be irradiated is N-1. apparatus.