JP2684952B2 - Disc recording method and disc recording apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk recording method and a disk recording apparatus for recording data on a phase change optical disk by a pulse length recording method.

[0002]

2. Description of the Related Art A phase change type optical disk is one of disk-shaped recording media capable of high density recording of data. Data recording on a phase-change optical disk is performed by irradiating a rotating disk with a focused laser beam to heat and melt the recording film. The ultimate temperature of the recording film and the cooling process differ depending on the intensity of the recording laser light, and a phase change of the recording film occurs.
That is, when the laser light is strong, the recording film is rapidly cooled from the high temperature state to become amorphous, and when the laser light is relatively weak, the recording film is crystallized because it is gradually cooled from the medium to high temperature state. The amorphized portion is usually called a mark, and the crystallized portion is called a space. Then, the binary information is stored in the mark and the space. In addition, the phase change type optical disk is capable of erasing old data and recording new data at the same time with one laser beam,
That is, direct overwrite is possible.

During reproduction, weak laser light is emitted so that the recording film does not cause a phase change, and the reflected light is detected.
Amorphized mark portions have low reflectance, and crystallized space portions have high reflectance. Therefore, the difference in the reflected light amount between the mark portion and the space portion is detected to obtain the reproduction signal.

There are a pulse position recording method (PPM) and a pulse length recording method (PWM) as a method of recording data on a phase change type optical disk. The PPM records relatively short marks having a constant pulse length with various spaces, and records information is assigned to the positions of the marks. On the other hand, PWM records marks of various lengths with various spaces, and assigns recording information to both the mark length and the space length. Therefore, the information recording density of PWM is higher than that of PPM.

When performing PWM recording, a long mark is recorded as compared with PPM recording. When a long mark is recorded on a phase change type optical disk by irradiating a constant laser power to the mark portion, the width in the radial direction becomes thicker toward the latter half of the mark due to the heat storage effect of the recording film. This seriously impairs the signal quality, such as the unerased portion occurring when direct overwriting is performed, or the signal crosstalk between tracks is generated during reproduction. Therefore, a method has been reported in which the laser power or the recording pulse width is controlled so that the width in the radial direction is not widened in the latter half of the mark, and the power is weakened in the latter half of the mark to record the mark.

[0006]

As described above, in the phase change optical disk, the mark portion has a lower light reflectance than the space portion. On the contrary, this means that the mark portion has a higher heat absorption rate. Further, the required heats of fusion differ depending on whether the phase of the recording film is amorphous or crystalline. Therefore, during direct overwriting, even if the same laser power is applied to an existing mark and space for recording, the heat absorption amount and the reached temperature are different and the edge position of the formed mark varies. Particularly, in the conventional recording method in which the irradiation light amount is weakened in the latter half of the mark, the edge position variation at the end of the mark becomes remarkable, and the deterioration of the overwrite characteristic is a problem.

Further, in order to increase the recording density, it is conceivable to shorten the length of marks and spaces to be recorded. In this case, especially when the space length becomes small, the heat at the end of the recorded mark conducts through the space and affects the temperature rise at the start of the next mark, or conversely, the heat at the start of the next recorded mark is generated. Thermal interference occurs that affects the cooling process at the end of the previous mark. When thermal interference occurs in the conventional recording method, the edge position of the mark fluctuates, and there is a problem that the error rate during reproduction increases.

The present invention is to solve the above-mentioned problems, to record the width of a long mark in the radial direction substantially constant, to reduce the fluctuation of the mark edge position during direct overwriting, and to shorten the mark. and purpose thereof is to provide a disc recording method and a disc recording apparatus which thermal interference does not occur edge position variation does not occur between the marks in space.

[0009]

[0010]

[0011]

In order to achieve the above object, a disk recording method of the present invention is a phase change type optical disc.
Amorphous film is irradiated by irradiating the recording film of
And a second state laser beam is emitted to conclude.
Data by pulse length recording by forming a crystal state
A disk recording method for overwriting
Near the beginning of the mark recorded in the amorphous state and
In the vicinity of the terminal, the first power is irradiated for a certain period of time, and the mark
The middle part of the power is less than the first power and the first power
The power switching cycle is shorter than the fixed period
Alternately, irradiate, and near the end of the mark.
After the irradiated first power, a power smaller than the second power is applied.
The work is irradiated for a certain period.

Further, the disk recording apparatus of the present invention comprises a light source.
And the laser light emitted from the light source
The recording film on the disk is irradiated with the laser light of the first power to
Form a fast state and irradiate it with a laser beam of a second power
By forming a crystalline state, the data can be recorded by the pulse length recording method.
And a means for overwriting the phase change type optical disk.
Means for rotationally driving the light source, and a pulsed drive for the light source.
A disk recording device having a loose driving means, comprising:
The pulse driving means is recorded in the amorphous state.
The first power near the beginning and end of the mark
Is irradiated for a certain period of time in the middle part of the mark.
The first power and a power smaller than the first power are
The irradiation is switched alternately in a cycle smaller than the fixed period.
After the first power applied near the end of the mark,
A power smaller than the second power is emitted for a certain period.
As described above, the light source is driven.

[0013]

[0014]

[0015]

[0016]

[0017]

[0018]

[0019]

Therefore, according to the present invention, the beginning portion of the mark is irradiated with a laser beam strong enough to start writing the mark for a certain period, and thereafter, the middle portion of the mark is alternately switched between the strong and weak laser beams. By irradiating the minimum required laser power to continue writing, long marks are recorded with a constant width without excess heat in the latter half of the marks. Further, by providing a period for irradiating a strong laser beam to the mark end portion, the reached temperature of the mark end portion becomes high and amorphous is stably formed, and the edge position of the mark end portion does not change even during direct overwriting. In addition, the end of the space,
The part with a small amount of irradiation heat immediately after the mark is
To prevent heat conduction through the base and reduce thermal interference between marks
It is possible to suppress the fluctuation of the edge position of the mark.

[0020]

[0021]

[0022]

[0023]

[0024]

[0025]

[0026]

[0027]

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows a block diagram of a first embodiment of a disc recording apparatus for realizing the disc recording method of the present invention, and FIG. 3 shows a signal waveform diagram of each part of the first embodiment.

First, the drawings will be described. In FIG.
1 is data, 2 is multi pulse generation circuit, 3 is multi pulse, 4 is adiabatic pulse generation circuit, 5 is adiabatic pulse, 6 is space length detection circuit, 7 is adiabatic effective pulse, 8 is a logic circuit, 9 is a first Control pulse, 10 is the second control pulse, 11
Is a laser diode, 12 is a main current source, 13 is a first addition current source, 14 is a second addition current source, 15 is a first switch, 16 is a second switch, and 17 is a data clock.

In FIG. 3, a is data 1, b is data clock 17, c is multi-pulse 3, d is adiabatic pulse 5, e is adiabatic effective pulse 7, and f is a first control pulse 9, g.
Shows the signal waveform of the second control pulse 10, h shows the current change of the laser diode 11, and i shows the state of the marks and spaces to be recorded. Also in FIG. 3, 50 is the data Hi period, 51 is the start portion of the data Hi period, 52 is the middle portion of the data Hi period, 53 is the end portion of the data Hi period, 54 is the inversion period of the multi-pulse, and 55 is Data Lo period, 56 is the beginning portion of the data Lo period, 57 is the ending portion of the data Lo period, 5
Reference numeral 8 indicates one cycle of the data clock.

Next, the operation will be described. Data 1 is PWM data having information on the lengths of the Hi period and the Lo period as illustrated in FIG. 3a. In the multi-pulse generation circuit 2, the start portion 5 of the Hi period of the data 1
A burst-like multi-pulse 3 which is inverted at a period 54 which is less than one period of the data clock is generated in the intermediate portion 52 excluding 1 and the end portion 53 (FIG. 3c). In the adiabatic pulse generation circuit 4, the adiabatic pulse 5 is generated at the beginning portion 56 and the end portion 57 of the Lo period of the data 1 for a period of one cycle or less of the data clock (FIG. 3d).

In the space length detection circuit 6, data 1
The adiabatic effective pulse 7 that is effective when the length is less than the predetermined value (here, the length is three times one cycle 58 of the data clock) is output (Fig. 3e). And
In the logic circuit 8, the data 1, the multi-pulse 3, the adiabatic pulse 5, and the adiabatic effective pulse 7 are logically operated to turn on / off a first switch 15 and a second switch 16 described later, respectively.
First control pulse 9 and second control pulse 10 for turning off
Is generated (FIGS. 3f and 3g).

The laser diode 11 is of a negative type in which the anode side is grounded, and the main current source 12
The first addition current source 13 and the second addition current source 14 are driven in parallel. In this embodiment, the laser power is controlled to three values, and the reproducing power, the erasing power, and the
Recording power. The main current source 12 supplies a current required for the laser diode 11 to emit light with a reproducing power, and the second addition current source 14 supplies a current required for the laser diode 11 to emit light with an erase power to the main current. Source 1
The first addition current source 13 supplies the current necessary for the laser diode 11 to emit light with the recording power together with the main current source 12 and the second addition current source 14.

Then, the first summing current source 13 is turned on / off by the first switch 15 and the second summing current source 14 is turned on / off by the second switch 16, respectively, whereby the current value of the laser diode 11 is controlled to three values. (Fig. 3h). That is,
The reproduction current is emitted by the current of the main current source 12, and the second
The current of the addition current source 14 is added to emit the erasing power,
Further, the current of the first addition current source 13 is added to emit the recording power. Then, by irradiating the disc with this three-value controlled laser beam, marks and spaces as shown in FIG. 3i are recorded.

Next, FIG. 2 shows a block diagram of a second embodiment of the disc recording apparatus for realizing the disc recording method of the present invention, and FIG. 4 shows a signal waveform diagram of each part of the second embodiment.

First, the drawings will be described. The parts having the same numbers and the same names as those in the first embodiment described above also have the same functions, and thus the description thereof will be omitted. In FIG. 2, 18
Is a logic circuit, 19 is a first control pulse, 20 is a second control pulse, 21 is a laser diode, 22 is a main current source, 2
3 is a first subtraction current source, 24 is a second subtraction current source, 25 is a first switch, and 26 is a second switch. In FIG. 4, f is the first control pulse 19 and g is the second control pulse 20.
Shows the signal waveform of each, h is the laser diode 2
1 shows a change in current.

Next, the operation will be described. In the logic circuit 18, the data 1, the multi-pulse 3, the adiabatic pulse 5, and the adiabatic effective pulse 7 are logically operated to turn on / off a first switch 25 and a second switch 26, which will be described later, respectively. And a second control pulse 20 is generated (FIGS. 4f and 4g).

The laser diode 21 is of a positive polarity type in which the cathode side is grounded, and the main current source 22
Drive with In this embodiment, the laser power is set to 3
The read power, the erase power, and the write power are controlled in order of decreasing value. The main current source 22 supplies a current necessary for the laser diode 21 to emit light with the recording power, and the second subtraction current source 24 has a current of the main current source 22 because the laser diode 21 emits with the erase power. The first subtraction current source 23 divides the current of the main current source 22 together with the second subtraction current source 24 because the laser diode 21 emits light with the reproduction power.

Then, the first subtraction current source 23 is turned on / off by the first switch 25 and the second subtraction current source 24 is turned on / off by the second switch 26, whereby the current value of the laser diode 21 is controlled to three values. (Fig. 4h). That is,
The recording power is emitted by the current of the main current source 22, the current of the second subtraction addition current source 24 is subtracted therefrom to emit the erase power, and the current of the first subtraction current source 23 is subtracted to emit the reproduction power. Then, by irradiating the disc with this three-value controlled laser beam, marks and spaces as shown in FIG. 4i are recorded.

Based on the above configuration and operation, the first aspect of the present invention
In the embodiment and the second embodiment, a strong laser power (recording power) necessary and sufficient to start writing the mark is irradiated at the start end portion of the mark, and the mark is continuously written at the intermediate portion of the mark by the multi-pulse driving. The minimum required laser power (switching between recording power and erasing power) is applied, and a strong laser power (recording power) is applied so that the amorphous portion at the edge portion of the mark is stably formed.

As a result, it is possible to record the width of the long mark in the radial direction substantially constant, and to reduce the fluctuation of the edge position at the end of the mark during direct overwrite. Further, in a short space where heat interference normally occurs between marks, weak laser power (reproduction power) is applied to the beginning and end portions by an adiabatic pulse to suppress heat conduction through the space. As a result, fluctuations in the mark edge positions on both sides of the short space can be reduced. Also,
In a long space where thermal interference between marks does not occur, adiabatic pulse driving is not performed, so that unerased residue does not occur in that portion, and direct overwrite characteristics can be improved.

As a condition for exerting the effect of the present invention, for example, the width of the mark start end portion 51 is set longer than one cycle of the data clock so that the laser power necessary and sufficient for writing the mark can be supplied. . Further, the inversion cycle 54 of the multi-pulse portion needs to be set small enough not to change the mark width in proportion to the switching of the recording power, and is set shorter than one cycle of the data clock.
Further, the width of the mark end portion 53 is preferably set to a length around one cycle of the data clock in order to raise the reached temperature of the mark end portion during recording to some extent.

Further, the widths 56 and 57 of the adiabatic pulse at the leading and trailing ends of the space reduce the thermal interference between the marks, and further, in order to prevent the unerased residue from occurring in that portion during direct overwriting, Setting shorter than the cycle is effective.

The space length to which the adiabatic pulse should be added often causes thermal interference only in the shortest space length existing in the data, and if the predetermined value is set to a value longer than the shortest space length by one cycle of the data clock. Good.

When the recording linear velocity of the disc changes, the laser power value for recording marks and spaces of the same size on the disc changes. Then, the optimum value of the pulse width of each part may change. Therefore, in an application where the recording linear velocity changes depending on the radial position of the disc, it is desirable to set the recording power of the laser and each pulse width according to the linear velocity. Hereinafter, an embodiment of the disk recording apparatus of the present invention corresponding to the change of the linear velocity will be described.

FIG. 5 shows a third embodiment of the disk recording apparatus of the present invention.
It is a block diagram of an example. In FIG. 5, 30 is the linear velocity data, 31 is the linear velocity data 30, and based on the linear velocity data 30, the multi-pulse generation circuit 2, the adiabatic pulse generation circuit 4, the space length detection circuit 6, the main current source 12, the first addition current source 13, It is a control circuit which controls each 2nd addition current source 14.
In other parts, the components having the same numbers and the same names as those in the previous embodiment have the same functions as those in the previous embodiment, so that the description thereof will be omitted.

For example, if the linear velocity is high when recording on the outer circumference of the disc, the linear velocity information is the linear velocity data 3
0 is input to the control circuit 31, and the control circuit 31 controls the main current source 11, the first addition current source 12, the second addition current source 13
The laser power is increased by increasing the current value of at least one of those in comparison with the case where the linear velocity is low.

Further, in the multi-pulse generating circuit 2, the period of the beginning portion of the data Hi period, the inversion cycle of the intermediate portion,
The end portion period, the start portion portion of the data Lo period in the adiabatic pulse generation circuit 4, the end portion period, and the predetermined value of the space length in the space length detection circuit 6 are optimal according to the increased laser power. Set to a value.

FIG. 6 shows a fourth embodiment of the disc recording apparatus of the present invention.
It is a block diagram of an example. Also in FIG. 6, the third
Similar to the embodiment, the control circuit 31 sets the recording power and the period of each portion to the optimum value according to the linear velocity.

Based on the above configuration and operation, the third aspect of the present invention will be described.
In the embodiment and the fourth embodiment, even in the application where the recording linear velocity is different depending on the disk radial position, the laser power and the pulse width of the recording signal are set to the optimum values according to the linear velocity, and any linear velocity is set. A long mark can be stably recorded with a constant width, and thermal interference in a short space can be reduced.

The disc recording method of the present invention is the first
It is possible to implement by using a part or all of the configuration of the disk recording apparatus of the fourth embodiment .

In addition, multi-pulse driving in the middle part of the mark
The operation will be described with an example in which the recording power and the erasing power are switched.
However, it is not limited to this.

Further, the power of the adiabatic pulse is called the reproduction power.
As described above, the same effect can be obtained with zero power at which the laser is not emitted at all. However, since it is difficult to obtain a good rising characteristic of the light emission waveform in the implementation circuit, it is preferable to use the reproduction power.

[0053]

According to the present invention, in the application of recording data on the phase change type optical disk by the pulse length recording method, it is possible to suppress the edge position fluctuation of the recording signal to the minimum and also the overwrite characteristic. Can be improved. As a result, it is possible to significantly improve the data recording density. Therefore, when it is used in an image file device having a huge amount of data information, its performance improving effect is remarkable.

[Brief description of the drawings]

FIG. 1 is a block diagram of a disk recording apparatus according to a first embodiment of the present invention.

FIG. 2 is a block diagram of a disk recording apparatus according to a second embodiment of the present invention.

FIG. 3 is a signal waveform diagram of each part of the disk recording apparatus according to the first embodiment of the present invention.

FIG. 4 is a signal waveform diagram of each part of the disc recording apparatus according to the second embodiment of the present invention.

FIG. 5 is a block diagram of a disk recording device according to a third embodiment of the present invention.

FIG. 6 is a block diagram of a disk recording device according to a fourth embodiment of the present invention.

[Explanation of symbols]

 2 Multi-pulse generation circuit 4 Adiabatic pulse generation circuit 6 Space length detection circuit 8 Logic circuit 11 Laser diode 12 Main current source 13 First addition current source 14 Second addition current source 15 First switch 16 Second switch 18 Logic circuit 21 Laser Diode 22 Main current source 23 First subtraction current source 24 Second subtraction current source 25 First switch 26 Second switch 31 Control circuit

Claims (5)

(57) [Claims] 1. A first power is applied to a recording film of a phase change optical disk.
Second laser beam to form an amorphous state,
To form a crystalline state by irradiating it with a laser beam of power
More overwriting data by pulse length recording method
Disk recording method, recording in the amorphous state
The first power is near the beginning and the end of the mark.
For a certain period of time, and the middle part of the mark is the first part
The cycle of switching between power and power smaller than the first power is
Alternately illuminate so that it is smaller than the certain period.
After the first power that was emitted near the end of the mark
A disk recording method comprising irradiating with a power smaller than the second power for a certain period of time . 2. The mark for a certain period of time near the starting end of the mark
The switching cycle of the middle part of the mark for a certain period near the end of
Period, and irradiating a power smaller than the second power
2. The disc recording method according to claim 1 , wherein at least one of the fixed periods is changed and recorded according to the linear velocity of the disc. 3. A light source and laser light emitted from the light source
Laser light of the first power on the recording film of the phase-change optical disk.
Is irradiated to form an amorphous state, and the second power level is
Pulse by irradiating laser light to form a crystalline state
Means for overwriting data in the long recording method, and
A means for rotationally driving the phase change optical disk and the light source
Disk recording provided with pulse driving means for pulse driving
In the apparatus, the pulse driving means is the amorphous
Near the beginning and end of the mark recorded in
The marker so that the first power is irradiated for a certain period of time.
In the middle part of the circle, the first power and less than the first power
Power is switched alternately at a cycle shorter than the above-mentioned fixed period
To irradiate near the end of the mark.
After the first power, a power smaller than the second power is
It is characterized in that the light source is driven so as to be irradiated for a fixed period.
And a disk recording device. 4. The pulse driving means is near the starting end of the mark.
Within the mark for a certain period of time, near the end of the mark
Smaller than the second power and the cycle of switching between parts
At least one of the fixed periods of
The disk according to claim 3, wherein the disk is changed according to the linear velocity of the circle.
Recording device. 5. A first power is applied to a recording film of a phase change type optical disk.
Second laser beam to form an amorphous state,
To form a crystalline state by irradiating it with a laser beam of power
More overwriting data by pulse length recording method
It is a disk recording device that repeats high level and low level.
Multi-pulse generating means for generating multi-pulses returned
And adiabatic pulse generation means for generating adiabatic pulse for a certain period
And at least the multipulse and the adiabatic pulse.
Recording film of the optical disk combined at a fixed timing
And a logic means for outputting a control signal of the laser beam for irradiating
And has the amorphous state based on the control signal.
Near the beginning and end of the mark recorded in the
The first power is irradiated for a certain period of time, and the middle part of the mark
Then, based on the multi-pulse included in the control signal
Alternating the first power and the power smaller than the first power
The irradiation is switched and the irradiation is performed near the end of the mark.
After 1 power, the adiabatic pulse included in the control signal
The power smaller than the second power is kept for a certain period.
A disk recording device characterized by irradiation.