JPH09190656A - Optical information recording method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the control load and to optimally adjust light output of a light source with a simple constitution. SOLUTION: In the optical information recording method that a light output of a semiconductor laser 6 is made into multiple pulses according to a recording signal and a clock signal having a constant frequency synchronized with the recording signal, and a magneto-optical disk 1 is irradiated with a light beam of this multiple pulse light output, and hence marks corresponding to the recording signal is recorded by changing duties of the clock signal, the pulse width of the multiple pulse light output is changed. Consequently, a control means for changing the pulse width of the multiple pulse light output of changing duties of the clock signal is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording method and apparatus for recording information on an information recording medium by using multivalued multi-pulse recording waveforms.

[0002]

2. Description of the Related Art FIG. 9 is a block diagram showing an example of a conventional magneto-optical recording / reproducing apparatus. In FIG. 9, a light modulation overwrite system (see Japanese Patent Laid-Open No. 62-175948).
An example of a device that can rewrite information and is a pit edge recording system as a recording system and capable of high density recording is shown. The data modulation method is (1-7)
It is assumed that the modulation method is adopted. In FIG.
Reference numeral 1 denotes a magneto-optical disk, which is an information recording medium. A recording layer 3 is formed on a transparent substrate 2 such as glass or plastic, and a protective layer 4 is further formed on the surface of the recording layer 3. The magneto-optical disk 1 is supported by a rotating shaft of a spindle motor by magnet chucking (not shown) or the like, and is rotated at a predetermined speed by driving the spindle motor.

On the lower surface of the magneto-optical disk 1, an optical head for irradiating a light beam to record and reproduce information on the disk is provided. Inside the optical head, various optical elements such as a semiconductor laser 6 which is a light source are provided. Explaining the optical head, first, the light beam emitted from the semiconductor laser 6 is emitted from the collimator lens 8
After being collimated by, the light passes through the polarization beam splitter 9 and enters the objective lens 7. Then, this incident light beam is focused by the objective lens 7 and focused on the disc 1 as a minute light spot.

A part of the light thus condensed is reflected by the disk surface and again passes through the objective lens 7 and enters the polarization beam splitter 9. This incident light is reflected by the polarization plane of the polarization beam splitter 9 toward the ½λ wavelength plate 10 side and separated from the incident light from the semiconductor laser 6. The separated reflected light enters the polarization beam splitter 11 via the ½λ wavelength plate 10, and is split into two light beams according to the magnetization direction of the recording layer 3 here. The divided light beams are respectively detected by the optical sensor 13 via the sensor lens 12, and the light reception signals of the respective optical sensors 13 are differentially detected by the differential amplifier 14, whereby the reproduction signal is converted into a magneto-optical signal. can get.

A control optical system is provided inside the optical head, and the reflected light from the disk 1 is detected.
In the error signal detection circuit, a focus error signal and a tracking error signal are generated based on the detection signal.
In the servo control circuit, the actuator 5 is driven based on these servo error signals to displace the objective lens 7 in the focus direction and the tracking direction,
Focus control is performed so that the light beam from the optical head is focused on the recording layer 3 of the disc 1, and tracking control is performed so that the light beam scans the information track of the disc 1 so as to follow. In FIG. 9, these control optical system, error signal detection circuit, and servo control circuit are omitted.

A magnetic head 19 is arranged on the upper surface of the magneto-optical disk 1 so as to face the optical head. The magnetic head 19 is driven by a drive current supplied from the magnetic head driver 20, and applies magnetic fields having different polarities to the disk 1 in accordance with recording and erasing of information. In this case, the magnetic head 19 is adapted to apply a magnetic field of equal intensity over the entire area of the disk 1 in the radial direction, and by applying magnetic fields having different polarities to the light beam irradiation site according to recording and erasing, Records and erases information.

The controller 17 is a main control circuit for controlling each part in the apparatus, and controls the rotation of a spindle motor (not shown), the control of the magnetic head driver 20, the LD driver 18 which is a drive circuit of the semiconductor laser 6, and the like. Take control. Further, the controller 17 performs a modulation process for processing the recording data transferred from the external host controller into a signal suitable for recording. In the apparatus of FIG. 9, since the (1-7) modulation method is used as described above, the controller 17 encodes the recording data (1-7) in accordance therewith, and the obtained recording signal is the multi-pulse converting circuit 15 Is supplied to. Here, in FIG. 9, the pit edge recording method in which information is provided to the edge of the recording pit as described above is adopted, but in such pit edge recording, especially the edge of the recording pit is used. Therefore, the recording is performed using a multi-valued multi-pulse recording waveform here.

In FIG. 9, as will be described later in detail, 4
A 4-valued multi-pulse recording waveform for recording with a value recording power is used, and the multi-pulse conversion circuit 15 generates a 4-valued multi-pulse recording signal according to the recording signal from the controller 17 and supplies it to the LD driver 18. . LD
The driver 18 has four current sources corresponding to four values, and supplies a driving current to the semiconductor laser 6 in accordance with a four-valued multi-pulse recording signal to control the recording power of the semiconductor laser 6 to control the recording power on the disk 1. Record information.

FIG. 10 is a circuit diagram showing a specific configuration of the multi-pulse conversion circuit 15. In FIG. 10, (1-
7) The data is a recording signal after (1-7) modulation by the controller 17, and the channel clock is a clock signal of a constant frequency generated by a clock generator (not shown). The recording signal is synchronized with the channel clock. One cycle of the channel clock is T (T: 1 channel width). The multi-pulse converting circuit 15 includes flip-flop circuits 100 and 101, an AND circuit 102, and an inverter circuit 1.
03, flip-flop circuits 104 and 105, an OR circuit 106, and AND circuits 107 and 108 in combination, and when (1-7) data (recording signal) is input, multi-valued recording power PH1, P
A modulation signal corresponding to H2, PL is output. That is, the OR circuit 106 outputs the modulation signal corresponding to PH1, the AND circuit 108 outputs the modulation signal corresponding to PH2, and the flip-flop 101 outputs the modulation signal corresponding to PL.
These PH1, PH2 and PL will be described later in detail.

FIG. 11 shows the multi-pulse conversion circuit 15 of FIG.
3 is a time chart showing signals of each part of FIG. The signals of FIGS. 11A to 11J are shown in FIGS.
It corresponds to the signal shown by. FIG. 11A shows a channel clock, and FIG. 11B shows a recording signal output from the controller 17. The recording signal is the flip-flop circuit 1
00, 101, and the channel clock is input to the flip-flop circuit 104 via the flip-flop circuits 100, 101, 105 and the inverter circuit 103. 11C is an output signal of the flip-flop circuit 100, FIG. 11D is an output signal of the flip-flop circuit 101, FIG. 11E is an output signal of the flip-flop circuit 104, and FIG. The output signal of the flip-flop circuit 105 is shown.

The output signals of the flip-flops 104 and 105 are ORed by the OR circuit 106, and the output signal is output as a modulation signal corresponding to the recording power PH1 as shown in FIG. 11 (h). Further, the output signal of the flip-flop circuit 100, the output signal of the flip-flop circuit 101 (inverted output), and the flip-flop circuit 105.
The output signal (inverted output) is ANDed by the AND circuit 107 and becomes a signal as shown in FIG. This signal is logically ANDed with the output signal of the inverter circuit 103 by the AND circuit 108, and the output signal is output as a modulation signal corresponding to the recording power PH2 as shown in FIG. 11 (i). The output signal (inverted output) of the flip-flop circuit 101 is output as a modulation signal corresponding to the recording power PL as shown in FIG. In this way, the multi-pulse conversion circuit 15 generates modulation signals corresponding to PH1, PH2, and PL, and the obtained modulation signals pass through the laser power switching line in FIG.
8 is supplied.

In the LD driver 18, the semiconductor laser 6 is responsive to the modulation signal from the multi-pulse converting circuit 15.
Information is recorded by supplying a drive current to the control signal and controlling the optical output of the semiconductor laser 6 in a four-valued multi-pulse recording waveform as shown in FIG. In FIG. 11 (k), PL is a recording power level for forming a low temperature level state in the recording layer 3 of the disc 1 (a state causing a low temperature process disclosed in Japanese Patent Laid-Open No. 62-175948), PH1 and PH2 are The recording power level that forms a high temperature level state (state that causes the high temperature process disclosed in the publication), Pb is a bottom value (reproducing power) of the recording power, which is a constant value. Further, in the LD driver 18, as described above, the PH from the multi-pulse generation circuit 15 is changed.
The modulation signals corresponding to 1, PH2, PL are supplied in parallel. However, these modulation signals are prioritized, and the LD driver 18 selects the modulation signals according to the priority order, and the semiconductors are accordingly selected. A drive current is supplied to the laser 6.

More specifically, FIG. 11 (h),
Although (i) and (j) are the modulation signals corresponding to PH1, PH2, and PL as described above, when all of these modulation signals are 1, the modulation signal with the highest priority is selected. The order of priority is PH1, PH2, PL, and Pb, and as shown in FIGS.
When H1 is 1, PH2 is 0, and PL is 1, the LD driver 18 has a modulated signal of PH1 and PL, so that the modulated signal of PH1 having a higher priority is selected. Next, when the modulated signal of PH1 is 0, the modulated signal of PH2 is 0, and the modulated signal of PL is 1 as shown in FIGS. 11 (h) to 11 (j), the modulated signal that is 1 in this case is only PL. Therefore, the PL modulation signal is selected.

Subsequently, when the modulation signal of PH1 becomes 0, the modulation signal of PH2 becomes 1, and the modulation signal of PL becomes 1, in this case, the modulation signal of PH2 and PL having the highest priority among PH2 and PL of the modulation signal which is 1 in this case. The signal is selected. LD in this way
The driver 18 selects the modulation signal. Also, L
A current source corresponding to PL, PH1, PH2, and Pb is provided inside the D driver 18, and by supplying a driving current to the semiconductor laser 6 from the current source according to the selected modulation signal, The recording power of the semiconductor laser 6 is controlled to a four-valued multi-pulse recording waveform as shown by 11 (k).

Here, in FIG. 11 (k), PH1 is pulse lighting for turning on and off at intervals of 1.5T and PH2 is turning on and off at intervals of 0.5T, and one cycle of pulse lighting for PH2 is 1T length of pit. It corresponds. In the example of FIG. 11, the leading multi-pulse recording waveform shows a recording waveform in the case of recording 3T pits. PH1 of 1.5T and PH2 of 0.5T are lit for one cycle, so that FIG. A pit of 3T is recorded on the information track of the disc 1 as shown in l). In addition, in the example of FIG. 11, 0.5T of Pb is provided before PH1 and 1.0T of Pb is provided after PH2, but the Pb before and after these are called a cooling gap. . Next, PH1 of 1.5T and 0.5T
The recording waveform of PH2 of 2 cycles corresponds to 4T pits, and the recording waveform of PH1 of 1.5T next to 2T pits corresponds to 2T pits. By irradiating the light beam of such a 4-level multi-pulse recording waveform, 4T pit, 2 as shown in Fig. 11 (l)
T pits can be recorded.

Although only the recording waveforms of 2T to 4T are shown in FIG. 11, in the case of recording 5T pits, PH1 of 1.5T is followed by PH2 of 0.5T intervals for 3 periods, and in the case of 6T pits or less. PH1 is the same, PH2 is 4 cycles, 7T pits PH2 is 5 cycles, 8T pits is P
H2 becomes 6 cycles. In (1-7) modulation, the shortest pit is 2T and the longest pit is 8T. Therefore, the shortest pit to the longest pit can be recorded by using the multi-pulse recording waveform according to the pit length as described above. You can In this way, by turning on PH1 and then turning on PH2 in pulses, the temperature of the recording medium can be maintained at a predetermined temperature, and an excessive rise in temperature can be prevented.
Further, the pit edge recording is a recording method in which information is given to the position of the edge of the pit as described above. However, in the above-described recording method using the four-valued multi-pulse recording waveform, the fluctuation of the pit edge can be suppressed. In particular, it can be suitably used for pit edge recording.

Next, when reproducing the information recorded on the magneto-optical disk 1, the LD driver 18 controls the recording power of the semiconductor laser 6 to a constant reproducing power (Pr) under the control of the controller 17. The target information track is scanned with the light beam of the reproduction power. At this time, a magneto-optical signal is obtained from the differential amplifier 14 as described above, the magneto-optical signal is binarized in a signal processing circuit (not shown), and a predetermined signal processing is performed using the binarized signal. By performing, the reproduction data can be obtained and the recorded information can be reproduced.

[0018]

By the way, in the above-mentioned conventional magneto-optical recording / reproducing apparatus, when the recording medium is different, the thermal structure is also different. Therefore, the recording characteristics are different depending on the recording medium and the accuracy of the pit edge position is also high. It will change. Therefore, to prevent this, depending on the recording medium, PH1 and PH2
It is necessary to adjust the recording power level. However, in the pit edge recording, the precision of the pit edge position is particularly required, so that the power level of PH1 and PH2 requires more precise control, and the control of the drive current to the semiconductor laser of the LD driver is also highly precise. Required. Therefore, when controlling the recording power levels of PH1 and PH2 in this way, there is a problem that the control load of the control circuit increases and the scale of the control circuit also increases.

In view of the above-mentioned conventional problems, the present invention provides an optical information recording method and apparatus capable of reducing the control load and optimally adjusting the light output of the light source with a simple structure. It is intended.

[0020]

SUMMARY OF THE INVENTION An object of the present invention is to multi-pulse the optical output of a light source in accordance with a recording signal and a clock signal of a constant frequency synchronized with the recording signal, and to convert the multi-pulse optical output. In the optical information recording method of recording a mark corresponding to the recording signal by irradiating the information recording medium with a light beam, the pulse width of the multi-pulse optical output is changed by changing the duty of the clock signal. Is achieved by the optical information recording method.

Another object of the present invention is to have means for multi-pulseing the optical output of the light source according to a recording signal and a clock signal synchronized with the recording signal, and the optical beam of the multi-pulse optical output. In an optical information recording apparatus for recording marks corresponding to the recording signal by irradiating the information recording medium with the pulse, the pulse width of the multi-pulse optical output is changed by changing the duty of the clock signal. This is achieved by an optical information recording device characterized by having control means for controlling.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a configuration diagram showing one embodiment of the present invention. In this embodiment, the magneto-optical disk 1 which is a recording medium rotates at a constant linear velocity. Further, in FIG. 1, the same parts as those of the conventional device of FIG. That is, the magneto-optical disk 1, the magnetic head 19 and the magnetic head driver 20 are the same as those in FIG. The optical head for recording and reproducing information on the disk 1 is also the same, and the semiconductor laser 6, the collimator lens 8, the polarization beam splitter 9, the objective lens 7, the actuator 5, and the 1/2 λ wavelength plate 10 provided inside thereof are the same. The polarization beam splitter 11, the condenser lens 12, and the optical sensor 13 are the same as those in FIG.

The light beam emitted from the semiconductor laser 6 is focused by the objective lens 7 and focused on the magneto-optical disk 1 as a minute light spot. In this case, also in FIG.
An error signal detection circuit that detects a focus error signal and a tracking error signal based on the reflected light from the disk 1,
A servo control circuit for performing focus control and tracking control based on these servo error signals is provided.
Then, by the control operation of the servo control circuit, the light beam emitted from the optical head is controlled so as to follow the information track of the rotating disk 1 while keeping the focus state on the recording layer 3 to scan. .

Further, in this embodiment, the envelope detection circuit 21 for detecting the envelope of the magneto-optical signal output from the differential amplifier 14, the binarization circuit 22 for binarizing the magneto-optical signal, and the binarized signal A phase comparator 23 that outputs a signal according to the lengths of the mark and the space is provided. These circuits are used to adjust the recording power of the semiconductor laser 6 by changing the pulse width of the multi-pulse recording waveform as described later in detail. The envelope detection circuit 21 detects a peak value of a magneto-optical signal by a peak detection circuit, a bottom detection circuit by which a bottom value is detected, and a peak value and a bottom value obtained by these two detection circuits. It consists of an output circuit. The intermediate value between the peak value and the bottom value of the magneto-optical signal obtained by the envelope detection circuit 21 is output to the binarizing circuit 22 as a slice level, and the binarizing circuit 22 uses this intermediate value to convert the magneto-optical signal into two. Valued. The phase comparator 23 detects the pulse widths of the mark and space of the binarized signal and outputs a signal corresponding to the difference between the pulse widths. A signal corresponding to this difference in pulse width is sent to the multi-pulse conversion circuit 15 as an electric signal such as a voltage.

The multi-pulse converting circuit 15 is a circuit for generating a multi-pulse signal according to the recording signal modulated by the (1-7) modulation as described above. In this embodiment,
As described above, a signal corresponding to the difference between the pulse widths of the mark and the space is fed back from the phase comparator 23 to the multi-pulse circuit 15, and the multi-pulse conversion circuit 15 changes the pulse width of the multi-pulse recording waveform according to this signal. Is configured. Multi-pulse circuit 1
The configuration and operation of 5 will be described later in detail. The LD driver 18 is the same as that shown in FIG. 9, and is a laser drive circuit for driving the semiconductor laser 6 in accordance with the multi-pulse signal sent from the multi-pulse forming circuit 15. Also,
Reference numeral 16 is a temperature sensor provided near the disk 1. The temperature sensor 16 will be described later in detail.

The controller 17 is the main control unit of the magneto-optical recording apparatus of this embodiment, and is a spindle motor (not shown).
To control the rotation of the magneto-optical disk 1 and the magnetic head driver 20 for recording, erasing, and reproducing, thereby controlling the magnetic field of the magnetic head 19 according to the operation mode. Further, the controller 17 controls the LD driver 18 to set the recording power of the semiconductor laser 6 at the time of recording and reproducing, and controls the optical head to the disk 1
Seek control is performed to seek to the target information track. Further, in the controller 17, the recording data is converted into (1-
7) Modulate to generate a recording signal or a channel clock. As described above, the controller 17 controls the data processing and the reproduction of the recorded information on the disc 1 by controlling the data processing and each unit in the apparatus. In addition, the controller 17
As will be described later in detail, when the disc 1 is set in the apparatus, control is performed to optimally adjust the pulse width of the multi-pulse recording waveform according to the characteristics of the disc 1.

FIG. 2 is a circuit diagram showing a concrete example of the multi-pulse conversion circuit 15 used in this embodiment. In FIG.
First, the channel clocks CK1 and CK2 are the channel clock sent from the controller 17 and the clock signal generated from the output signal of the phase comparator 23. A sawtooth signal generating circuit (not shown) that generates a sawtooth signal having the same frequency as that of the channel clock from the controller 17 is provided in the multipulse circuit 15 of FIG. The channel signal CK1 and CK2 having the same frequency and different duty are generated by binarizing the state signal using two comparators at different slice levels.

Further, the two slice levels change according to the output signal of the phase comparator 23, and the duty of the two channel clocks CK1 and CK2 changes according to the change. As a method of changing the duty of the channel clocks CK1 and CK2, other than this, for example, by using a programmable pulse generator and inputting a reference clock as a trigger, a program is preliminarily programmed according to the output of the phase comparator 23. It is also possible to obtain a clock with a specified duty.

The multi-pulse converting circuit 15 shown in FIG. 2 will be further described. 2, the same parts as those of the multi-pulse conversion circuit of FIG. 10 are denoted by the same reference numerals, and flip-flop circuits 100, 101, 104 and 105, AND circuits 102, 107 and 108, an inverter circuit 103, and an OR circuit 106. Is the same as in FIG. However, in FIG. 10, the output of the inverter circuit 103 and the AND circuit 107 is logically ANDed by the AND circuit 108 to obtain the modulated signal corresponding to PH2, but in this embodiment, the inverter circuit 109 is newly provided. In addition, the AND circuit 108 obtains the modulation signal of PH2 by taking the logical product of the output of the inverter circuit 109 and the output of the AND circuit 107.

In addition, the channel clock CK described above
1 is input to the flip-flop circuit 104 via the flip-flop circuits 100, 101, 105 and the inverter circuit 103, and the channel clock CK2 is input to the inverter circuit 109. Then, the (1-7) modulated recording signal is transferred to the flip-flop circuits 101 and 10
2, and a multi-pulse modulation signal corresponding to the recording signal is generated. That is, the OR circuit 106 outputs the modulation signal corresponding to PH1, the AND circuit 108 outputs the modulation signal corresponding to PH2, and the inverted output of the flip-flop circuit 101 outputs the modulation signal corresponding to PL.

FIG. 3 is a time chart showing signals of respective parts of the multi-pulse converting circuit 15. In FIG. 3, PH
The signals of the respective parts after the pulse widths of 1 and PH2 are adjusted according to the medium characteristics are shown. Further, FIG. 3 shows a signal when a medium having a characteristic that the heat diffusion is slow and the heat accumulation is large is used as the characteristic of the recording medium. In this embodiment, the pulse widths of PH1 and PH2 of the multi-pulse recording waveform are adjusted so that the recording marks are optimally formed.
The method of adjusting the pulse width of the multi-pulse recording waveform will be described later in detail. FIG. 3A shows the sawtooth signal output from the sawtooth signal generation circuit as described above.

This sawtooth signal is compared by two comparators with slice levels having different levels as shown in FIG. 3A, and as a result, as shown in FIG. 3B, the channel clock CK1 and FIG. ), The channel clock CK2 is generated. Channel clock CK1, C
The duty of K2 changes according to the output signal of the phase comparator 23 as described above, and the pulse width of PH1 and PH2 of the multi-pulse recording waveform changes accordingly. FIG. 3D shows a (1-7) modulated recording signal.

Further, FIG. 3 (e) shows a multi-pulse conversion circuit 2
Output signal of the flip-flop circuit 100 in FIG.
3F shows the output signal of the flip-flop circuit 101 (normal output), FIG. 3G shows the output signal of the flip-flop circuit 104, and FIG. 3H shows the output signal of the flip-flop circuit 105 (normal output). Shows. The output signal of the flip-flop circuit 104 of FIG. 3 (g) and the output signal of the flip-flop circuit 105 of FIG. 3 (h) are logically ORed by the OR circuit 106, and the output is PH1 as shown in FIG. 3 (j). Is output as a modulated signal corresponding to. Also, FIG. 3 (i)
The output signal of the AND circuit 107 of FIG. 3 and the signal obtained by inverting the channel clock CK2 of FIG.
A modulated signal corresponding to PH2 is output. Further, the output signal (inverted output) of the flip-flop circuit 101 is directly output as a modulation signal corresponding to PL as shown in FIG.

The multi-pulse modulation signal generated by the multi-pulse conversion circuit 15 in this way is the LD driver 18
Are supplied in parallel. The LD driver 18 has four current sources corresponding to PL, PH1, PH2, and Pb as described above, and when these modulation signals are 1, according to the predetermined priority order as described above. The modulation signal is selected, and the semiconductor laser 6 is selected from the corresponding current source.
Is supplied with a drive current. As a result, the recording power of the semiconductor laser 6 is controlled to a 4-level multi-pulse recording waveform according to the recording signal as shown in FIG. Then, by irradiating the disc 1 with a light beam having such a recording waveform, recording pits corresponding to the recording signal are recorded as shown in FIG.

Here, in FIG. 3, it is explained that the signal is obtained when a medium having a slow heat diffusion and a large heat accumulation is used as a characteristic of the recording medium as described above. The duty of the channel clock CK1 is small and the pulse width of PH1 is wide. That is, in this case, since the heat diffusion of the recording medium is slow and the heat accumulation is large, by increasing the pulse width of PH1, P
By increasing the irradiation time of H1 and substantially increasing the recording power, the temperature rise of the medium at the pit edge tip is accelerated and the formation of the record mark is controlled so that the pit tip portion can be recorded in an appropriate shape. . FIG. 3 (k) shows a modulation signal corresponding to the conventional PH1, that is, a channel clock CK.
The modulation signal when the duty of 2 is 50% is shown. As is clear from a comparison between this and the modulation signal corresponding to PH1 of the present embodiment of FIG. 3 (j), P of FIG. 3 (j) is obtained.
The pulse width of H1 is wider, and the difference between the pulse widths corresponds to the increment of the pulse width of PH1.

On the other hand, the duty of the channel clock CK2 is increased and the pulse width of PH2 is narrowed accordingly. That is, in this case, since the heat diffusion of the recording medium is slow and the heat accumulation is large, the pulse width of PH2 is narrowed, the irradiation time of PH2 is shortened, and the recording power thereof is substantially reduced, whereby The formation of recording marks is controlled so that the medium temperature rise at the trailing edge can be suppressed and recording can be performed in an appropriate shape even at the trailing edge of the pit. FIG. 3 (m) is a conventional modulated signal corresponding to PH2, that is, a modulated signal when the duty of the channel clock CK1 is 50%. As is clear from a comparison between this and FIG. 3 (l), FIG. The 3 (l) PH1 modulation signal is narrower, and the difference corresponds to the decrease in the PH1 pulse width. Note that FIG. 3 (o) shows a modulation signal corresponding to the conventional PL, which is the same as FIG. 3 (n) of the present embodiment. Thus, as shown in FIG. 3 (p), PH1 and PH2 of the multi-pulse recording waveform are recorded according to the characteristics of the recording medium.
By controlling the pulse width of, the recording mark of each length can be recorded in an appropriate shape as shown in FIG.

Next, in the case of a recording medium having a characteristic that the heat diffusion is fast and the heat accumulation is small contrary to the above recording medium, PH
The pulse widths of 1 and PH2 are controlled in the opposite direction. FIG. 4 is a time chart showing signals of respective parts at this time. 4A to 4Q correspond to FIGS. 3A to 3Q, respectively. First, the channel clock CK1 is shown in FIG.
The duty changes so as to increase. Along with this, the pulse width of the modulated signal of PH1 is shown in FIG.
As shown in FIG. 4 (p), the pulse width of PH1 of the multi-pulse recording waveform also changes.
That is, in this case, since the heat diffusion of the medium is fast and the heat accumulation is small, the rise of the medium temperature at the pit tip is suppressed by narrowing the pulse width of PH1, and the shape of the pit tip is recorded in an appropriate shape. It is controlled so that it can be done.

Next, the channel clock CK2 is shown in FIG.
As shown in FIG. 4C, the duty is changed to be smaller, and along with this, the pulse width of PH2 of the multi-pulse recording waveform is widened as shown in FIG. 4P. In this case, since the heat diffusion of the medium is fast and the heat accumulation is small, PH2
The width of the pulse is widened to suppress the decrease in the temperature of the medium, and the pit shape is controlled to be recorded in an appropriate shape at the rear end of the pit. As a result, the recording mark is recorded in an appropriate shape as shown in FIG. Depending on the characteristics of the medium, both the pulse widths of PH1 and PH2 may be wide, and PH1, PH2
It goes without saying that both the pulse widths of PH2 may be narrowed. Thus, in this embodiment,
By varying the pulse width of the multi-valued multi-pulse recording waveform according to the characteristics of the recording medium, control is performed so that the recording mark can be properly recorded.

Therefore, a specific method of adjusting the pulse width of the multi-pulse recording waveform of this embodiment will be described with reference to FIGS. 5 and 6. The adjustment of the pulse width is performed by the disc 1
Shall be performed when is set in the device. In addition, in the present embodiment, an adjustment will be described as an example when a medium having a slow heat diffusion and a large heat accumulation is used as a characteristic of the recording medium. First, when the disk 1 is set, the controller 17 controls the multi-pulse converting circuit 15 to set the duty of the channel clocks CK1 and CK2 to a predetermined duty determined in advance. In this embodiment, FIG.
As shown in (a) and (b), the channel clock CK1,
The duty of CK2 is set to 50%. Next, the controller 17 causes the optical head to seek a predetermined write test area of the disk 1, and when reaching the write test area, controls each unit and records a predetermined signal.

The signal to be recorded is preferably a pattern in which the asymmetry of the reproduced signal when it is reproduced appears clearly, that is, a pattern in which the difference in the intermediate value of the amplitude of the reproduced signal appears clearly. For this reason, in the present embodiment, the longest pit of the (1-7) modulation, that is, the 8T mark and space, and the shortest pit, the 2T mark and space, are recorded. FIG. 5C shows (1-7) modulated 8T mark, 8T space and 2T mark, 2T at this time.
A recording signal of space, FIG. 5D shows a multi-pulse recording waveform of the semiconductor laser 6 at this time. When the disk 1 is irradiated with a light beam having this multi-pulse recording waveform and a magnetic field in a fixed direction is simultaneously applied from the magnetic head 19, 8T marks, 8T spaces, 2T spaces, and 2T marks are recorded as shown in FIG. To be done. In FIG. 5 (e), since the medium has a slow heat diffusion and a large heat accumulation as described above, the tip is thin at the 8T mark, and the teardrop shape is such that it gradually spreads backward.
The 2T mark is also shorter than the ideal mark.

When the recording is completed, the controller 17 controls each part to move the optical head to the head position of the previously recorded write test area, and scans the write test area with the reproducing light beam to perform recording. Signal is reproduced. At this time, the reproduction signal is reproduced from the differential amplifier 14 as a magneto-optical signal as shown in FIG. 5 (f) and sent to the envelope detection circuit 21 and the binarization circuit 22. here,
As for the reproduction signal of FIG. 5 (f), the amplitude of the reproduction signal of the 2T mark is small because the 2T mark has a small amplitude. Therefore, the intermediate value of the reproduced signal amplitude of the 2T mark is offset more negatively than the intermediate value of the reproduced signal amplitude of the 8T mark, and the asymmetry is large as described above.

The envelope detection circuit 21 detects the intermediate value of the amplitude of the reproduced signal, and the binarization circuit 22 binarizes the reproduced signal with the intermediate value as the slice level.
That is, the reproduced signal of 8T mark and 8T space is shown in FIG.
At the slice level of the intermediate amplitude value as shown in FIG. 5, the reproduction signals of the 2T mark and the 2T space are also binarized at the slice level of the intermediate value of the amplitude. In the phase comparator 23, the difference in pulse width between the binarized signals of the 8T mark and the 8T space is detected by using the reference clock from the controller 17, and the signal corresponding to the difference between the pulse widths of the mark and the space is converted into multi-pulses. It is output to the circuit 15. Similarly, the difference between the pulse widths of the binarized signals of the 2T mark and the 2T space is detected, and a signal corresponding to the difference is output to the multi-pulse conversion circuit 15.

In the multi-pulse conversion circuit 15, the channel clock C is output according to the output signal of the phase comparator 23.
The duties of K1 and CK2 change, and the pulse widths of the modulation signals of PH1 and PH2 also change accordingly. At this time, the duty of the channel clocks CK1 and CK2 is 2T and the difference between the pulse widths of the 8T mark and the 8T space.
The difference between the pulse widths of the mark and the 2T space changes in a decreasing direction, and accordingly, the pulse widths of the modulated signals of PH1 and PH2 also change in a direction in which the difference between the pulse widths of the preceding mark and space disappears. .

More specifically, for example, the duty of the channel clock CK1 is changed so as to eliminate the difference between the pulse widths of the binarized signals of the 8T mark and the 8T space, and the pulse width of PH2 is changed. Then 2
The duty of the channel clock CK2 is changed in the direction in which the difference between the pulse widths of the binarized signals of the T mark and the 2T space is reduced to change the pulse width of PH1.

When these series of operations are completed, the controller 17 controls each part in exactly the same manner as described above to record the 8T mark, 8T space and 2T mark, 2T space on the disc 1 again, and reproduces it. The difference between the pulse widths of the binarized signals of the 8T mark and the 8T space, and the 2T
The pulse widths of PH1 and PH2 are changed by changing the duty of the channel clocks CK1 and CK2 in the direction in which the pulse widths of the binarized signals of the mark and the 2T space have no difference. In this way, recording, reproduction, channel clock CK
PH1, PH2 due to changes in the duty of 1, CK2
Repeat a series of operations such as adjusting the pulse width of
When the difference between the pulse widths of the binarized signal between the 8T mark and the 8T space and the difference between the pulse widths of the binarized signal between the 2T mark and the 2T space have disappeared, the adjustment of the pulse widths of PH1 and PH2 is completed.

FIG. 6 is a diagram showing the signals of the respective parts after the adjustment of the pulse widths of PH1 and PH2 as described above is completed. 6 (a) to 6 (f) are the same as FIG. 5 (a) before adjustment.
To (f). The channel clock CK1 has a small duty as shown in FIG. 6A, and the channel clock CK2 has a large duty as shown in FIG. 6B. In addition, this channel clock CK1, CK
As shown in FIG. 6D, the pulse width of PH1 is wide and the pulse width of PH2 is narrow with the change of 2.

That is, in this embodiment, since the medium is slow in heat diffusion and large in heat accumulation as described above, the duty of the channel clock CK1 is reduced to form the 2T mark or the tip of the 8T mark. The pulse width of PH1 is widened, and the irradiation time of PH1 is adjusted to be correspondingly longer. Further, the duty of the channel clock CK2 is increased to reduce the pulse width of PH2 forming the marks after the 2T mark, and the irradiation time of PH2 is shortened by that amount. As described above, by adjusting the pulse widths of PH1 and PH2, as shown in FIG.
As described above, the temperature rise of the medium at the tip of the mark is accelerated and the temperature rise of the medium is suppressed until the trailing end of the mark thereafter, so that the 8T mark has a teardrop shape as shown in FIG. 6 (e). It can be seen that the image is recorded in an appropriate shape without being formed. Also, it can be seen that the 2T mark is recorded in an appropriate shape without being reduced in shape. Therefore, when the recording mark of FIG. 6 (e) is reproduced, as shown in FIG. 6 (f), the reproduction signal of the 8T mark and the 8T space and the reproduction signal of the 2T mark and the reproduction signal of the 2T space have the same amplitude intermediate value. It is possible to obtain a reproduction signal without asymmetry.

In this embodiment, P of the multi-pulse recording waveform is used.
Since the pulse widths of H1 and PH2 are adjusted according to the characteristics of the recording medium, in the process of forming a recording mark on the medium, the irradiation time width of the light beam of the semiconductor laser from the front end to the rear end of the mark at each time Can be optimally adjusted to control the shape of the recording mark to be an appropriate shape. Therefore, the shape of the recording mark does not become a teardrop shape or becomes smaller than an appropriate shape, and the recording can be performed in an appropriate shape regardless of the characteristics of the recording medium. Therefore, it is possible to obtain a reproduction signal with a small error rate, and it can be suitably used particularly for pit edge recording in which information is provided at the pit edge. Moreover, since the irradiation time width of the light beam of the semiconductor laser is adjusted by changing the pulse width of the multi-pulse recording waveform, the laser power value is controlled as compared with the conventional method of adjusting the laser power value by the current control of the LD driver. The load can be reduced and adjustment can be performed with a simple configuration.

Next, in FIG. 1, the temperature sensor 16 is arranged close to the lower surface of the disk 1 as described above, but the pulse width of the multi-pulse recording waveform is adjusted by the temperature detected by the temperature sensor 16 in the following. Will be described. The temperature sensor 16 detects the environmental temperature of the device, particularly the ambient temperature near the laser irradiation part of the disk 1, and the controller 17 constantly monitors the temperature detected by the temperature sensor 16. Here, in this embodiment, the pulse widths of PH1 and PH2 of the multi-pulse recording waveform are readjusted every time the temperature changes by 5 ° C., for example. For example, when the temperature at the time of the previous adjustment is 25 ° C. and this rises to 30 ° C., the controller 17 controls each unit and adjusts the pulse widths of PH1 and PH2 in exactly the same manner as described above. By thus adjusting the pulse widths of PH1 and PH2 according to the temperature, stable recording can be performed regardless of the temperature change.

When adjusting the pulse widths of PH1 and PH2, in the normal information recording / reproducing apparatus, operations such as recording, reproduction, and adjustment of the pulse width based on the mark and space of the reproduction signal are performed as described above. Although it is necessary to repeat the operation, an information recording / reproducing apparatus having a direct verify function using two beams or the like reproduces almost simultaneously with recording every time recording is performed, and the difference between the pulse widths of the mark and space of the binary signal is It is possible to adopt a method of feeding back to the pulse widths of PH1 and PH2 so as to eliminate them. Therefore, in such an apparatus, one adjustment can be completed during the recording operation, and the pulse width can be adjusted in a short time. In addition, the power value of the semiconductor laser is set to P
Although the four values of b, PL, PH1, and PH2 are used, the pulse width of the multi-pulse recording waveform is exactly the same when multi-pulse recording is performed by setting this value to three values, that is, PH1 and PH2 are the same. Should be adjusted. Further, the adjustment of the pulse width of the multi-pulse recording waveform as described above may be performed not only when the disc is exchanged but also before the recording, or periodically after the disc is inserted at regular intervals. Needless to say.

Next, an embodiment in which the disk 1 rotates at a constant angular velocity as in the CAV system or the zone CAV system will be described. In the present embodiment, the P of the multi-pulse recording waveform is recorded at a plurality of radial positions on the disk 1 by the method described above.
When the pulse widths of H1 and PH2 are adjusted and the pulse width values at that time are stored in the memory and data is recorded on the disk 1, PH1 and PH1 are recorded according to the radial position of the disk 1 by using the values. The pulse width of PH2 is adjusted. By doing so, when the disk 1 rotates at a constant angular velocity and the recording position of the disk 1 changes from the inner circumference to the outer circumference, the same recording power is maintained over the entire area of the disk 1 without changing the power values of PH1 and PH2. It is to make stable recording with.

More specifically, first, channel clocks CK1 and CK2 are 5 in the middle region of the disk 1, respectively.
In order to record ideal recording marks around 0%,
Recording power values such as PH1 and PH2 are set in advance. That is, this means that the linear velocity becomes slower in the inner circumference of the disc 1 and the energy for forming the recording mark is less, so that the recording pulse width of the multi-pulse recording waveform becomes narrower, and the linear speed becomes faster in the outer circumference. Since the amount of energy required to form the recording mark is large, it is necessary to change the duty of the channel clock in the direction of widening the pulse width. Therefore, the duty of the channel clock should be about 50% in the middle region of the disk 1. For example, it is based on the reason that a wide dynamic range can be obtained when adjusting the pulse widths of PH1 and PH2. PH1, P at this time
The pulse width of H2 is stored in the memory.

Then, at the predetermined positions on the inner and outer circumferences of the disk 1, the difference between the pulse widths of the binarized signals of the 8T mark and the 8T space, and the 2T mark are measured by the same method as in the previous embodiment.
The pulse widths of PH1 and PH2 of the multi-pulse recording waveform are adjusted so that there is no difference in the pulse width of the binarized signal of the 2T space, and the obtained pulse width value is stored in the memory. In this way, when the pulse widths of PH1 and PH2 at the inner circumference, the middle circumference, and the outer circumference of the disk 1 are stored in the memory and data is actually recorded on the disk 1, PH1 and PH2 are recorded according to the recording radial position of the disk 1. The pulse width value of is calculated by interpolating the pulse widths of the inner circumference, the middle circumference, and the outer circumference stored in the memory, and the pulse widths of PH1 and PH2 are adjusted to the obtained values.

FIG. 7 is a diagram showing signals at various portions when recording is performed on the inner circumference of the disk 1 by adjusting the pulse width in this way. FIG. 7A shows the channel clock CK1, FIG.
7B shows the channel clock CK2, and FIG.
7) A modulated recording signal. 7D is an output signal of the flip-flop circuit 100 in the multi-pulse converting circuit 15 of FIG. 2, FIG. 7E is an output signal of the flip-flop circuit 101, and FIG. 7F is a flip-flop circuit 104. 7 (g) shows the output signal of the flip-flop circuit 105, and FIG. 7 (h) shows the output signal of the AND circuit 107.

In the inner circumference of the disk 1, the duty of the channel clocks CK1 and CK2 is as shown in FIG.
Change as shown in (b), and as a result, PH1, PH2
7 (i) and 7 (k) also change, and the pulse widths of PH1 and PH2 of the multi-pulse recording waveform are as shown in FIG.
As shown in (o), the duty of the channel clocks CK1 and CK2 is narrower than when it is 50%. That is, since the linear velocity is slow in the inner circumference of the disk 1 and the energy for forming the recording mark may be small, the pulse widths of PH1 and PH2 are smaller than the pulse width in the middle circumference of the disk 1 as shown in FIG. Is also narrowing. PH1,
PH2 is adjusted to an optimum pulse width in accordance with the recording radial position of the disk 1, and even in the inner circumference of the disk 1, FIG.
The mark is recorded in an appropriate shape as shown in (p).
7 (j), 7 (l), and 7 (n), the channel clocks CK1 and CK2 have a duty of 50%.
The modulated signals of PH1, PH2 and PL at the time of are shown.

FIG. 8 is a diagram showing signals of respective parts when recording is performed on the outer periphery of the disk 1 by adjusting the pulse widths of PH1 and PH2 as described above. 8A to 8P correspond to FIGS. 7A to 7P, respectively. Disc 1
In the outer circumference of the channel, the duty of the channel clocks CK1 and CK2 changes in the direction opposite to that in the inner circumference as shown in FIGS. 8 (a) and 8 (b), and the pulse widths of PH1 and PH2 accordingly. Channel clock CK1, as shown in (o)
It is wider than when the duty of CK2 is 50%. That is, the linear velocity is fast on the outer periphery of the disc 1.
Since much energy is required to form the mark, P
The pulse widths of H1 and PH2 are wider than the pulse width of the disk 1 in the middle circumference. Also in this case, since the pulse widths of PH1 and PH2 are adjusted to the optimum values according to the recording radial position of the disc 1, it is possible to record the mark in an appropriate shape as shown in FIG.

In the above embodiment, the pulse widths of PH1 and PH2 were adjusted at the inner circumference, the middle circumference and the outer circumference of the disk 1, but the pulse width is adjusted for each predetermined radial position with a finer interval. Then, it is desirable to store the pulse width at each position in a memory and interpolate the pulse width at each radial position of the disk based on that. Also in this embodiment, as in the previous embodiment, the controller 17 monitors the temperature detected by the temperature sensor 16, and if the temperature changes by a predetermined temperature,
It is assumed that the duty of the channel clocks CK1 and CK2 is changed and the pulse widths of PH1 and PH2 are readjusted.

Further, also in this embodiment, as in the previous embodiment, the adjustment of the pulse width at the predetermined recording radius position of the disc 1 is performed when the disc 1 is inserted, before recording, or at regular time intervals. And Also in this embodiment,
Needless to say, the present invention can be applied to the case of a three-valued recording power as in the previous embodiment. Further, in the light modulation overwrite method, when the recording power PL has a function of causing a low temperature process as in the present embodiment, in order to optimize the power, the PL of the PL is changed according to the linear velocity of the disk 1. It is desirable to control the value.

[0059]

As described above, the present invention has the following effects. (1) By changing the pulse width of the multi-pulse recording waveform by changing the duty of the clock signal, the control load of the light output of the light source can be greatly reduced compared to the conventional one, and optimum adjustment can be made with a simple circuit configuration. be able to. (2) By adjusting the pulse width of the multi-pulse recording waveform according to the characteristics of the recording medium, it is possible to always record the recording mark in an appropriate shape regardless of the characteristics of the recording medium, and to record highly reliable information. Can be realized. (3) By adjusting the pulse width of the multi-pulse recording waveform according to the linear velocity of the recording medium, the recording power can be constantly controlled over the entire area of the recording medium, regardless of the recording position.
The recording mark can be recorded in an appropriate shape. (4) By adjusting the pulse width of the multi-pulse recording waveform according to the environmental temperature, it is possible to always record an appropriate mark regardless of the temperature change.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of an optical information recording device of the present invention.

FIG. 2 is a circuit diagram showing a specific example of the multi-pulse conversion circuit of the embodiment of FIG.

FIG. 3 shows the operation of the embodiment of FIG. 1 and FIG.
9 is a time chart for explaining an example of using a medium having a large heat accumulation.

FIG. 4 is a time chart for explaining the operation of the embodiment shown in FIGS. 1 and 2 by taking as an example the case where a medium with rapid heat diffusion and small heat accumulation is used.

FIG. 5 is a diagram for explaining a method of adjusting the pulse width of a multi-pulse recording waveform according to the present invention.

FIG. 6 is a diagram showing signals, recording marks, and reproduction signals at various portions after adjustment of the pulse width of a multi-pulse recording waveform.

FIG. 7 is a diagram showing signals of respective portions at an inner peripheral position when a pulse width is adjusted according to a recording radial position when a disk rotates at a constant angular velocity in another embodiment of the present invention. .

FIG. 8 is a diagram showing signals of respective portions at an outer peripheral position when a pulse width is adjusted according to a recording radial position when a disk rotates at a constant angular velocity in another embodiment of the present invention.

FIG. 9 is a block diagram showing a conventional magneto-optical recording / reproducing apparatus.

FIG. 10 is a circuit diagram showing in detail the multi-pulse conversion circuit of FIG.

FIG. 11 is a time chart showing signals of respective parts in FIGS. 9 and 10.

[Explanation of symbols]

1 Magneto-optical disk 3 Recording layer 5 Actuator 6 Semiconductor laser 7 Objective lens 13 Optical sensor 14 Differential amplifier 15 Multi-pulse circuit 16 Temperature sensor 17 Controller 18 LD driver 19 Magnetic head 20 Magnetic head driver 21 Envelope detection circuit 22 Binarization Circuit 23 Phase Comparator 100, 101, 104, 105 Flip Flop Circuit 102, 107, 108 AND Circuit 103, 109 Inverter Circuit 106 OR Circuit

Claims (14)

[Claims] 1. An optical output of a light source is multi-pulsed according to a recording signal and a clock signal of a constant frequency synchronized with the recording signal, and an information recording medium is irradiated with the multi-pulsed optical beam of the optical output. According to the optical information recording method for recording a mark corresponding to the recording signal, the pulse width of the multi-pulse optical output is changed by changing the duty of the clock signal. Recording method. 2. The optical information recording method according to claim 1, wherein the duty of the clock signal is changed according to the characteristics of the recording medium to change the pulse width of the multi-pulse optical output. An optical information recording method, characterized in that a recording mark forming operation is controlled. 3. The optical information recording method according to claim 1, wherein the duty of the clock signal is changed according to the linear velocity of the recording medium to change the pulse width of the multi-pulse optical output. An optical information recording method, characterized in that the recording power is controlled to be substantially constant. 4. The optical information recording method according to claim 1, wherein the duty of the clock signal is changed according to the temperature around the recording medium. 5. The optical information recording method according to claim 1, wherein the clock signal is a first optical output for recording a mark of a predetermined length of the multi-pulse optical output,
A first clock signal and a second clock signal are respectively provided corresponding to the second optical outputs which are subsequently emitted periodically according to the length of the mark, and the first clock signal and the second clock signal are provided. An optical information recording method, wherein the pulse widths of the first and second optical outputs are changed by changing the duty of the clock signal. 6. The optical information recording method according to claim 2, wherein the characteristic of the recording medium is a thermal characteristic based on a thermal structure of the recording medium. 7. The information recording medium is provided with a means for converting the optical output of the light source into multi-pulses according to a recording signal and a clock signal synchronized with the recording signal, and irradiating the information recording medium with a light beam of the multi-pulse optical output. The optical information recording apparatus for recording a mark corresponding to the recording signal has a control unit for changing the pulse width of the multi-pulse optical output by changing the duty of the clock signal. An optical information recording device characterized by: 8. The optical information recording apparatus according to claim 7, wherein the control unit changes the duty of the clock signal in accordance with the characteristics of the recording medium to generate a pulse of the multi-pulse optical output. An optical information recording apparatus, characterized in that a width of a recording mark is controlled to control a recording mark forming operation. 9. The optical information recording apparatus according to claim 7, wherein the control unit changes the duty of the clock signal in accordance with the linear velocity of the recording apparatus of the recording medium, thereby performing the multi-pulse conversion. An optical information recording apparatus characterized in that a recording power is controlled to be substantially constant by changing a pulse width of an optical output. 10. The optical information recording apparatus according to claim 8, wherein the control means records a mark and a space having a predetermined length on the recording medium, and reproduces the recorded mark and the space. Means for outputting a signal according to a difference in length between the mark and the space, and changing the duty of the clock signal so that there is no difference in the length between the mark and the space based on the signal. Optical recording device. 11. The optical information recording apparatus according to claim 9, wherein the control means performs duty of the clock signal so that optimum recording power can be obtained at a plurality of recording radial positions of the recording medium having different linear velocities. And a storage means for storing the duty value of the clock signal, and based on the duty value stored in the storage means, the clock signal of the clock signal is generated according to the linear velocity of the recording position of the recording medium. An optical information recording device characterized by changing a duty. 12. The optical information recording device according to claim 7, wherein the clock signal is a first optical output for recording a mark of a predetermined length of the multi-pulse optical output, followed by the first optical output. The control means comprises a first clock signal and a second clock signal corresponding to the second optical output periodically emitted according to the length of the mark, and the control means controls the first and second clock signals. An optical information recording device, characterized in that the pulse widths of the first and second optical outputs are changed by respectively changing the duty of the signal. 13. The optical information recording apparatus according to claim 7, wherein the control unit changes the duty of the clock signal in accordance with the temperature of a temperature sensor provided near the recording medium. Optical information recording device. 14. The optical information recording device according to claim 8, wherein the characteristic of the recording medium is a thermal characteristic based on a thermal structure of the recording medium.