JPH0935357A - Write testing method and optical information recording and reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a device capable of sufficiently coping with the speeding up and the contriving of the high density of an information recording by correctly recording recording bits, regardless of the variation of recording powers. SOLUTION: A prescribed signal is recorded by changing recording powers on a magneto-optical disk 1 and the power level PHth immediately before the high temp. level state of the disk 1 starts is detected based on reproducing signal amplitudes detected in an amplitude detecting circuit 17 by reproducing the disk 1. Next, the value of a power level PL forming a low temp. level state is determined by a CPU 18 from the obtained PHth . Then, the power level forming a high temp. state is calculated by the CPU 18 by changing prescribed constants τ while using the relational expression between a power level PH1 and a power level PH2 forming the high temp. level state. Moreover, signals having different lengths are recorded on the disk 1 with the power level obtained by an asymmetrical circuit 19 in which a slice level automatic following circuit is provided and the difference between intermediate values of peak values and the bottom values of reproducing signals is detected to be outputted to the CPU 18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a write test method for adjusting the recording power of multivalue control of a light source to an optimum value in optical information recording, and an optical information recording / reproducing apparatus using the same. .

[0002]

2. Description of the Related Art Conventionally, as an apparatus for irradiating an information recording medium with a light beam to optically record or reproduce information, a reproduction-only recording medium in which information is previously recorded is reproduced. Device, write-once device that records information pits by opening the recording film with heat, device that changes the crystalline state of the medium and records information by the difference in reflectance, change the direction of magnetization of the perpendicular magnetization film There is a rewritable device that records information pits.

FIG. 12 is a block diagram showing a rewritable optical modulation overwrite type magneto-optical disk device. In FIG. 12, reference numeral 1 is a magneto-optical disk which is an information recording medium, and a magnetic film 2 is formed on a transparent substrate such as glass or plastic. The magneto-optical disk 1 is mounted on the rotating shaft of a spindle motor 3 and is rotated at a predetermined speed by driving the spindle motor 3. An optical head 4 is arranged on the lower surface of the magneto-optical disk 1,
A bias magnet 13 is arranged on the upper surface so as to face the optical head 4. A semiconductor laser 5 serving as a recording / reproducing light source is provided in the optical head 4.
The light beam emitted from is collimated by the collimator lens 6, then passes through the polarization beam splitter 7, and enters the objective lens 8. The incident light beam is focused by the objective lens 8 and focused on the magnetic film 2 of the magneto-optical disk 1 as a minute light spot. When recording information, the light beam of the semiconductor laser 5 is modulated in accordance with the information signal and applied onto the information track of the magneto-optical disk 1. On the other hand, at the time of recording information, the bias magnet 13 causes the magneto-optical disk 1 to move.
A magnetic field in a fixed direction is applied to, and a series of information is recorded by the application of this magnetic field and the irradiation of the modulated light beam.

The light beam applied to the magneto-optical disk 1 is reflected by the medium surface. This reflected light again enters the polarization beam splitter 7 through the objective lens 8, is reflected by the polarization plane toward the beam splitter 9 side, and is separated from the incident light of the semiconductor laser 5. The beam splitter 9 splits the incident light beam into two light beams, and one light beam is received by the optical sensor 11 via the sensor lens 10. Optical sensor 1
The received light signal of 1 is the AT / AF circuit (auto tracking,
Auto focus control circuit) 12 is input to AT / A
The F circuit 12 generates a tracking error signal and a focus error signal based on the received light signal. Then, the objective lens actuator 14 is driven based on the obtained tracking error signal and focus error signal to displace the objective lens 8 in the tracking direction and the focus direction, thereby performing tracking control and focus control.

On the other hand, when the recorded information on the magneto-optical disk 1 is reproduced, the light beam of the semiconductor laser 5 is set to a reproducing power at which recording cannot be performed, and the reproducing light beam is scanned to a target track. The recorded information is reproduced. That is, the reflected light of the reproduction light beam from the disc surface is received by the optical sensor 16 via the objective lens 8, the polarization beam splitter 7, the beam splitter 9, and the sensor lens 15. The light reception signal of the optical sensor 16 is sent to a reproduction signal processing circuit (not shown), and the recorded information is reproduced by performing a predetermined signal processing there. Of course, even at the time of reproduction, the reflected light of the reproduction light beam is received by the optical sensor 11,
The AF circuit 12 performs tracking control and focus control based on the received light signal.

Next, the recording process of the optical modulation overwrite system in the apparatus of FIG. 12 will be described. In addition,
This light modulation overwrite method is described in detail, for example, in JP-A-63-239637.
First, the magnetic film 2 of the magneto-optical disk 1 is composed of a first magnetic layer and a second magnetic layer exchange-coupled to each other. The coercive force of the first magnetic layer at room temperature is larger than that of the second magnetic layer,
The Curie temperature of the first magnetic layer is lower than the Curie temperature of the second magnetic layer. When recording information on the disc 1, the second magnetic layer having the higher Curie temperature is initialized in one direction, and then overwriting is performed by intensity modulation of the laser beam from the optical head 4. here,
As the laser beam, two types of laser power having different powers of the first type and the second type are used. The laser power of the first type is a power level enough to raise the temperature of the disk 1 to the Curie temperature of the first magnetic layer (power level PL forming a low temperature level state), and the power level of the second type is a second magnetic power of the disk 1. Power level enough to raise the Curie temperature of the layer (power level P that forms a high temperature level state
H).

More specifically, first, when two kinds of power levels of the laser beam are modulated according to information and the first kind of laser power (PL) is irradiated, the magnetization of the first magnetic layer having a low Curie temperature is magnetized. Only the magnetization disappears, and the magnetization developed in the subsequent cooling process at the irradiation site is in a stable direction with respect to the initialized second magnetic layer by exchange coupling with the second magnetic layer having a higher Curie temperature. Orient to. Next, when the second kind of laser power is irradiated, the magnetization of the first and second magnetic layers disappears at the irradiated portion, and the magnetization of the second magnetic layer that appears during the subsequent cooling process is biased. Orient in the direction of the magnetic field. Then, the magnetization of the first magnetic layer is oriented in a stable direction with respect to the magnetization of the second magnetic layer by exchange coupling, and information is recorded. By selecting the first and second types of laser power according to the information as described above, the magnetization of the first magnetic layer is oriented in the initialization direction with the first type of laser power, and the second type of laser power is selected. Then, the magnetization of the first magnetic layer is oriented in the direction of the bias magnetic field to record information. In this way, two types of laser power are controlled, and during this recording, overwriting is possible regardless of the magnetization state of the first magnetic layer before recording.

[0008]

The magneto-optical disk device described with reference to FIG. 12 is a device by overwriting of the optical modulation system as described above, and erases information in order to meet the demand for high-speed recording of information. It is possible to record information without performing. In recent years, in order to increase the density of information, pit edge recording in which both edges of a recording pit have meaning of information has become mainstream.
However, it is necessary to record the recording pits accurately and stably in order to speed up the recording of information and increase the density of information as described above. Recording power fluctuates due to dirt. Therefore, conventionally, there has been a problem that the recording pits change due to the fluctuation of the recording power, and it is not possible to sufficiently cope with the speeding up and the density increasing of the recording.

The present invention has been made in view of the above conventional problems, and an object thereof is to change the temperature inside the apparatus, the objective lens,
An object of the present invention is to provide a write test method and an optical information recording / reproducing apparatus capable of accurately recording a recording pit regardless of dirt on a recording medium.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to control the recording power of a light source by multi-valued control to record information on an information recording medium, and perform a write test on the recording medium to perform the write test. A write test method for adjusting a multilevel recording power to an optimum value, wherein a predetermined signal is recorded on the recording medium by changing the recording power, and a high temperature level state of the recording medium is recorded based on the reproduced signal amplitude. Detecting the power level immediately before the start of the recording, the power level for forming the low temperature level state on the recording medium based on the obtained power level, the power level for forming the low temperature level state and the high temperature Using the relational expression of the power level forming the level state and changing the predetermined constant of this relational expression to calculate the power level forming the high temperature state In addition, signals having different lengths are recorded on the recording medium at the obtained power level, and a high temperature level state is formed based on the difference between the peak value and the bottom value of the reproduction signal of the signals having different lengths. Determining the power level.

Another object of the present invention is an optical information recording / reproducing apparatus for recording information by controlling the recording power of a light source on an optical information recording medium by multi-valued control, and recording a predetermined signal on the recording medium. Means for recording while changing the power and detecting the power level immediately before the high temperature level state of the recording medium based on the reproduction signal amplitude, and the low temperature level state on the recording medium based on the obtained power level And a relational expression between the power level forming the low temperature level state and the power level forming the high temperature level state, and changing the predetermined constant of the relational expression to determine the high temperature level state. Means for calculating a power level to be formed, and a reproduced signal of a signal having a different length recorded on the recording medium with the calculated power level It is achieved by an optical information recording and reproducing apparatus characterized in that it comprises a means for determining a power level to form a high-temperature level state on the basis of the difference between the intermediate value between the peak value and the bottom value.

[0012]

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 block diagram showing an embodiment of the optical information recording / reproducing apparatus of the present invention. In FIG. 1, the same parts as those of the conventional device of FIG. 12 are designated by the same reference numerals and the description thereof will be omitted. That is, in FIG. 1, the magneto-optical disk 1, the magnetic film 2, the spindle motor 3, the AT
The AF circuit 12 is the same as that of FIG. Also in the optical head 4, the semiconductor laser 5, the collimator lens 6, the objective lens 8, the deflection beam splitters 7 and 9,
It is composed of sensor lenses 10 and 15, optical sensors 11 and 16, and an objective lens actuator 14, and has the same structure as the optical head 4 of FIG. The optical head 4 is configured to move in the radial direction of the magneto-optical disk 1 by a mechanism (not shown) so that a desired information track can be accessed. In the present embodiment, the (1-7) code is adopted as the modulation method of the recording data, and the magneto-optical disk 1
When the data is recorded in, the recording data is encoded by the CPU 18 by the (1-7) code. Then, the semiconductor laser drive circuit 20 drives the semiconductor laser 5 in accordance with the encoded signal to record a series of information.

Further, in the present embodiment, the amplitude detection circuit 17 for detecting the amplitude of the reproduction signal obtained by the optical sensor 16.
Is provided. The amplitude detection circuit 17 uses the magneto-optical disk 1 when performing a write test as described later in detail.
Power level (PHth) immediately before the high temperature process of
The amplitude of the reproduction signal is detected in order to detect. The amplitude value of the reproduction signal is taken into the CPU 18 by the A / D converter in the CPU 18. Asymmetry detection circuit 19
Is a circuit for detecting asymmetry (symmetry) of reproduced signals of two recording pits having different lengths during a write test as described later. Inside the asymmetry detection circuit 19, there is provided a slice level automatic tracking circuit for detecting a peak value and a bottom value of a reproduction signal and always detecting an intermediate value thereof as a slice level. The intermediate value (slice level) of the mark reproduction signal is detected and the difference is output. The output of the asymmetry detection circuit 19 is also taken into the CPU 18 by the A / D converter and used to determine the power level forming the high temperature level state on the disk 1 as described later in detail.

The CPU 18 is a processor circuit which constitutes a main control section of the optical information recording / reproducing apparatus of this embodiment, and controls each section in the apparatus to record / reproduce information. Also, CP
The U18 controls the write test as described later in detail, and controls to adjust each recording power in the multi-value control of the semiconductor laser 5 to the optimum value.

FIG. 2 is a diagram showing a lighting waveform of the semiconductor laser 5 of this embodiment. FIG. 2 shows, as an example, a laser lighting waveform when a 4T pattern is recorded. In FIG. 2, PL is a power level for forming a low temperature level state (erasure) on the magnetic film 2 of the magneto-optical disk 1, PH1
And PH2 are power levels for forming a high temperature level state (recording), and Pr is a reproducing power, which is a constant value. P
r is the reproduction power, which is Pb (the bottom value of the recording power) at the time of recording information, and Tfb (0.
It is provided for a time of 5T) and a time of Trb (1.0T) after PH2. Tfb is called a front cooling gap, and Trb is called a rear cooling gap.
PH1 is provided for a time of Th1 (1.5T). P
The period of H2 is Tp (1.0T) and the lighting time is Th2.
(0.5T), which is pulse lighting that turns on and off at intervals of 0.5T. In this embodiment, as shown in FIG.
The recording power of the semiconductor laser 5 is controlled by four values of L, PH1, PH2 and Pr, and the values of PL, PH1 and PH2 are set to the maximum values by a write test.

FIG. 3 is a diagram showing the correspondence between the recording pattern and the laser lighting waveform. FIG. 3A shows a recording pattern, and FIG.
FIG. 3B shows a laser lighting waveform corresponding to this, but in the present embodiment, when recording the space of the recording pattern, FIG.
It is assumed that the semiconductor laser 5 is turned on by DC as shown in (b). Further, when the 4T mark is recorded, the laser lighting waveform as described in FIG. 2 is recorded, and for the 2T mark, only the waveform of PH1 is obtained as shown in FIG. 3B. 3T
For the mark, PH1 is 2T, as shown in FIG.
It is the same as 4T, but there is only one PH2 pulse lighting. Although not shown in FIG. 3 below, the PH1 is the same for the 5T mark and the PH2 has three pulse lights.
For the 6T mark, four PH2 pulse lights, 7T
The mark increases to 5, the 8T mark increases to 6, and so on.

In this way, PH1 is turned on and then PH1 is turned on.
The pulse lighting of No. 2 is for maintaining the temperature of the recording medium at a predetermined temperature and preventing the temperature from rising too high. In addition, the pit edge recording described above is a recording method in which information is provided at the edge position of the pit.
By controlling 1 and PH2, the fluctuation of the pit edge can be suppressed. Therefore, such a laser beam control method can be suitably used particularly for pit edge recording. For the space, DC lighting of PL is performed as described above. In this embodiment, the (1-7) code is adopted as described above, and in this case, the shortest pit is 2T and the longest pit is 8T. Also, FIG.
(C) shows a laser lighting waveform when the space is pulse-lit, which will be described later in detail.

Next, the write test method of this embodiment will be described. First, the recording power levels PL, PH1, PH in the multi-valued control of the semiconductor laser 5 described with reference to FIG.
The relational expression 2 will be described. First, if the temperature change of the medium due to laser lighting is simplified, it can be expressed by the following equation.

[0019]

[Equation 1]

[0020]

[Equation 2] Here, τ is the thermal characteristic of the recording medium, the thermal diffusion constant characterized by the linear velocity, P ₀ is the laser power level, and T ₀ is the laser lighting time.

Subsequently, when the relational expression of heat cutoff is derived by using the expressions of the temperature rising and cooling processes of the expressions (1) and (2),

[0022]

(Equation 3) Becomes Th1 is the time of PH1 as shown in FIG.
rb is the time of Pr after PH2, and Pb is the bottom value of the laser power during recording. As shown in FIG. 2, Ts is the sum of the cooling gap times Tfb and Trb and the TH1 time Th1. That is, Ts is

[0023]

## EQU4 ## Ts = Tfb + Th1 + Trb (4)

The above equation (3) is a relational expression expressing the relation between PL and PH1, and is based on the following grounds. This will be described with reference to the 2T laser lighting waveform in FIG. That is, in FIG. 3B, the period of 0.5T of the previous cooling gap and the 1.5T of PH1 after that.
Of the cooling gap for the period of
The temperature of the recording medium at the end of the period T and the period of 0.5T of the previous cooling gap, PH1 of 1.
The temperature of the recording medium needs to be the same when the period of 5T and the period of 1.0T of the subsequent cooling gap are all PL. Therefore, from this relationship, the relationship between PL and PH1 can be expressed by an expression (3),
The relationship between PL and PH1 is known.

Next, using the equations (1) and (2), the multi-pulse relational expression, that is, the relational expression between PH1 and PH2 is derived.

[0026]

(Equation 5) Becomes Th1 is the time of TH1 and TP is T as shown in FIG.
Th2 is the time of one cycle of the H2 pulse, and Th2 is the pulse lighting time of TH2.

Equation (5) is a relational expression expressing the relation between PH1 and PH2, and is based on the following grounds. FIG. 3 (b)
Using the 3T laser lighting waveform of P1, the medium temperature at the end of the 1.5T period of PH1 and P
H1 1.5T period, then 0.5 at PL level
The medium temperature must be the same at the end of the period T and the period of 0.5T of PH2. Therefore, from this relationship, the relationship between PH1 and PH2 can be expressed by equation (5).
It becomes like the formula, and the relationship between PH1 and PH2 can be obtained. In this embodiment, PH1, PH are calculated by using the relational expressions (3) and (5) at the time of the write test as described later in detail.
By calculating 2 and performing test recording on the disc 1 with the obtained value, PH1 and PH2 are adjusted to the optimum values.

Therefore, a specific write test method of this embodiment will be described with reference to FIG. This light test
For example, it is performed when the magneto-optical disk 1 is set in the apparatus of FIG. 1, that is, when the disk 1 is exchanged. First, the write test of this embodiment is roughly divided into the following two steps. (1) In order to determine the laser power level PL for forming the low temperature level state on the magneto-optical disk 1, a process for detecting the laser power level PHth immediately before the high temperature level state starts is performed. (2) Using the above equations (3) and (5), the magneto-optical disk 1
Laser power level PH1 for forming a high temperature level state in the
And a process of obtaining the value of PH2.

First, the method (1) for obtaining PHth and the laser power level PL will be described. FIG.
When performing a write test in, the CPU 18 accesses the optical head 4 to a predetermined write test area of the magneto-optical disk 1 (S1). Next, the CPU 18 controls the drive circuit (not shown) of the bias magnet 13 and the semiconductor laser drive circuit 20 to apply the erase bias magnetic field to the write test area and scan the erase light beam to write. The test area is erased (S2). When the erasing is completed, the CPU 18 sets the initial value Pw of the recording power of the semiconductor laser 5 (S3). This is, for example, P recorded on the control track of the magneto-optical disk 1.
Use L to set this as the initial value.

When the initial value of the recording power is determined, the CPU 1
Reference numeral 8 controls each unit to record an 8T continuous pattern in the write test area with the power of the initial value (S4), and subsequently reproduce the recorded 8T continuous pattern to detect the amplitude level of the reproduction signal (S5). Of course, the amplitude level of this reproduction signal is detected by the amplitude detection circuit 17. The obtained amplitude level is taken into the CPU 18 by the A / D converter in the CPU 18 and stored in the internal memory (S5). CPU18
When the recording and reproduction with the initial values are completed in this way, the recording power is increased by adding ΔPw to the recording power Pw (S
6) Then, an 8T continuous pattern is recorded again in the write test area with this recording power (S4), and it is reproduced to detect and store the amplitude level of the reproduction signal (S5).

By repeating the processing of S4 to S6 in this way and increasing the recording power by a predetermined amount until the recording power reaches a predetermined recording power, as shown in FIG. You can get the relationship data. The predetermined recording power may be determined to be, for example, twice the PH recorded on the control track of the disc 1. With reference to FIG. 5, when the recording power is low, the reproduction signal amplitude is almost 0, but it suddenly rises from a certain recording power. The recording power at which the reproduction signal amplitude rises is the laser power PHth immediately before the start of the high temperature level state to be obtained.

Here, PHth immediately before the start of the high temperature level state described with reference to FIG. 5 has the characteristic that it changes according to the temperature change due to the medium characteristics. Therefore, the present invention pays attention to this characteristic, and based on PHth, PL, PH1, PH
By determining 2, the recording power is set according to the temperature change. The CPU 18 calculates the PHth from the data of the recording power and the reproduction signal amplitude stored in the memory.
Is stored in the memory (S7). With the above, P of (1)
The process of obtaining Hth ends. In this embodiment, as described above, the (1-7) code is adopted as the recording information modulation method, and the longest pit at this time, 8T, is used for detection of the reproduction signal amplitude.

Next, a method for obtaining the values of the laser power levels PH1 and PH2 forming the high temperature level state by using the equations (3) and (5) of (2) will be described. Subsequently, description will be made with reference to FIG. In FIG. 4, first, the CPU 1
8 sets the value of the laser power level PL that forms the low temperature level state to PL = α × PHth using PHth obtained previously (S8). However, the condition of α is PLmin / P
Hth <α <1.0. With the above, the value of PL is determined.

Subsequently, the CPU 18 sets the initial value of the thermal diffusion constant τ to about τ = T in order to calculate the laser power level that expresses the high temperature level state (S9). This value may be an appropriate value, and here, T which is the cycle of the basic clock of the recording signal is used. Next, the CPU 18 calculates PH1 and PH2 from the equations (3) and (5) using the value of τ (S10). Here, the relationship between the thermal diffusion constant τ and PH1 and PH2 is shown in FIG. The black circle in FIG. 6 is PH1, and the white circle is PH2. Both PH1 and PH2 become smaller as the thermal diffusion constant τ increases. The CPU 18 records 8T continuous and 2T continuous patterns in the write test area of the magneto-optical disk 1 with the calculated values of PH1 and PH2 (S).
11). For PL, the value obtained previously is used.

When the 8T continuous and 2T continuous patterns are recorded, the CPU 18 controls each part to reproduce it, and slice levels SL (8T) and 2T of the reproduced signal of the 8T pattern.
The slice level SL (2T) of the pattern reproduction signal is detected (S12). That is, the asymmetry detection circuit 19
Thus, the intermediate value between the peak value and the bottom value of the reproduction signal of the 8T continuous pattern and the 2T continuous pattern is detected. Then, in the asymmetry detection circuit 19, the slice level SL (8T) of the reproduction signal of the 8T continuous pattern and 2
Slice level SL (2
The difference ΔSL in T) is detected (S13), and the obtained value of ΔSL is fetched by the CPU 18 and stored in the memory (S).
14). Next, the CPU 18 adds Δτ to τ (S1
5), again substituting equations (3) and (5) into PH1
And PH2 calculation (S10), recording of 8T and 2T continuous patterns with the obtained values of PH1 and PH2 (S11), detection of the slice level of the reproduction signal (S12), detection of ΔSL (S13), and memory storage. The data is stored (S14).

The CPU 18 repeats the processing of S10 to S14 in this manner to increase the value of τ by Δτ. Then, it is repeated until the value of τ reaches a predetermined value, 8 times each time.
Slice level SL (8
T) and the slice level S of the reproduction signal of the 2T continuous pattern
When the difference ΔSL between L (2T) is detected, the data as shown in FIG. 7 can be obtained. FIG. 7 is data showing the relationship between ΔSL and PH1. Actually changing the value of τ (3),
PH1 and PH2 are calculated from the equation (5), and the obtained value is 8
T, 2T continuous pattern is recorded, and further 2 of the reproduced signal is recorded.
It is the actual measurement data obtained by measuring the difference ΔSL between the slice levels of T and 8T. Although PH2 is not shown in the drawing, similar data can be obtained. From this result, PH1 and PH2 obtained from τ when ΔSL (SL (8T) −SL (2T)) = 0 are the optimum PH.
1, the value of PH2. As described above, the optimum values of PL, PH1, and PH2 are determined (S16), and the write test ends.
The multilevel recording power of the semiconductor laser 5 is set to the optimum value obtained in each write test, and thereafter the information is recorded with the optimum recording power.

Here, in this embodiment, as described above, (1
-7) The code is adopted and 2 of the longest pit and the shortest pit is adopted.
The difference ΔSL between the slice levels (the intermediate value between the peak value and the bottom value) of the two reproduction signals is detected. This will be described. FIG. 8 shows reproduced signals of 8T continuous and 2T continuous patterns depending on the difference in the values of PH1 and PH2. First,
FIG. 8A shows a reproduced signal waveform when PH1 and PH2 are lower than the optimum values, and the level of the 2T continuous pattern is lower than that of the 8T continuous pattern. In this case, the 8T continuous pattern and the 2T continuous pattern have slice levels shown in FIG.
A difference occurs as shown in (a). FIG. 8B shows PH1, PH.
In the reproduced signal waveform when 2 is the optimum value, the slice levels of the 8T continuous pattern and the 2T continuous pattern are equal. FIG. 8C shows the case where PH1 and PH2 are higher than the optimum values, and the level of the 2T continuous pattern is higher than that of the 8T continuous pattern. Therefore, in this case, the slice levels of the 8T continuous pattern and the 2T continuous pattern are shown in FIG.
A difference occurs as shown in (c).

Next, in FIG. 8, the longest pit of 8T
Is in a saturated state, and in this state the intermediate value (slice level) between the peak value and the bottom value of the 8T reproduced signal.
Can be considered as 0. Therefore, when the slice level of the 8T reproduction signal and the slice level of the 2T reproduction signal match as shown in FIG. 8B, that is, when ΔSL is 0, both the 2T pit and the 8T pit are 8T It can be considered that the length was accurately recorded at 2T. Therefore, the values of PH1 and PH2 calculated using τ when ΔSL = 0 become the optimum power levels PH1opt and PH2opt to be obtained.

Next, the inventor of the present application conducted the following confirmation experiment in order to confirm whether the values of PH1 and PH2 obtained by the above write test are the optimum recording powers. Hereinafter, the experimental results will be described. First, on the magneto-optical disk 1, at a linear velocity of 12.56 m / s (rotation speed 3000 rpm, recording radius position 40.0 mm), the maximum frequency becomes 5.90 MHz (T = 42.37 ns) (1-7). Modulate random signals to PH1 and PH2
Recording was performed by changing the respective values, and the rising edge jitter and the falling edge jitter of the reproduced signal were measured. At this time, the value with the worse jitter on both edges was picked up and plotted, and the result as shown in FIG. 9 was obtained. The recording power P immediately before the high temperature level starts
Hth is 4.0 mW, and the value of PL is α =
As 0.9, it was set to 3.6 mW. In FIG. 9, the horizontal axis is PH1, the vertical axis is PH2, and PH1 and PH
A map of jitter in PH1-PH2, which represents the degree of jitter at the position indicated by 2, was created.

Also, in FIG. 9, the jitter of the reproduced signal is divided into 6 stages, and the range of 2.50 to 2.60 ns has the best jitter, and the range of 3.00 to 3.10 ns.
Indicates the area with the worst jitter. Therefore, if the jitter is plotted at each position of PH1 and PH2 as shown in FIG.
1 and PH2 can be evaluated. That is, the area with the lowest contour line in the map of FIG. 9 is the area with the smallest jitter, and the contour line becomes higher toward the outer periphery, and the jitter also increases accordingly. Therefore, in FIG. 9, the recording condition with the smallest jitter amount is the lowest position of the contour indicated by the mark X, that is, the combination of PH1 of 6.6 mW and PH2 of 6.6 mW.

On the other hand, the positions indicated by ● indicate the positions of PH1 and PH2 obtained by the above-mentioned write test. That is, as shown in FIG. 7, PH1 when ΔSL becomes 0 is 6.5 mW, and PH2 is not shown in the drawing, but similarly when PH becomes ΔSL becomes 0.
Since 2 is 6.5 mW, its position is indicated by the ● mark on the map of FIG. Therefore, when the optimum conditions of PH1 and PH2 obtained in the experiment, that is, the recording condition in which the amount of jitter is minimized and the optimum recording condition of the present invention are compared, as shown in FIG. It can be seen that the positions of are almost the same. This means that if the write test method of the present invention is used, the jitter of the reproduced signal is minimized, and each pit can be recorded accurately, and the recording power adjustment in multi-value control is accurate. Was confirmed.

Next, if the linear velocity of the disk 1 is constant at any recording position, it is not necessary to change the recording power,
For example, when the linear velocity differs depending on the recording radial position of the disk 1 as in the CAV system, it is necessary to change the recording power of the semiconductor laser accordingly. FIG. 10 shows the relationship between the recording radial position (linear velocity) of the disk 1 and the recording power in this case, and there is a proportional relationship between the linear velocity and the recording power. Therefore, in such a case, the write test described with reference to FIG. 4 is performed, for example, on the inner circumference, the middle circumference, and the outer circumference of the disk 1, and PL, PH1, and PH obtained at the respective positions.
The value of 2 is stored in the memory, and PL, PH1, and
The value of PH2 shall be changed. Although the write test has been described to be performed each time the disc 1 is replaced, other than this, the write test may be performed before information recording.
Even after is set, it may be periodically performed at regular intervals.

Further, in the above embodiment, the laser lighting waveform is the lighting waveform as shown in FIG. 2, but the present invention is not limited to this, and the lighting waveform as shown in FIG. 11 is also possible. Good. FIG. 11 shows a laser lighting waveform when recording a 4T pattern as in FIG.
The difference is that 0 is set. Even in this case, the present invention can be applied. At this time, it should be noted that the relational expression of heat cutoff is slightly different from that of the previous embodiment. That is, when there is no cooling gap at the front edge as shown in FIG. 11, the relational expression of heat cutoff is as follows.

[0044]

(Equation 6) However, Ts = Th1 + Trb.

Furthermore, in the embodiment, it is described that the space is DC-lit in FIG. 3B, but the present invention can be applied to the case where the space is pulse-lit as shown in FIG. 3C. However, in this case, since the pulse lighting is performed, when the PL level is determined as PL = α ′ × PHth from the value of the power level PHth immediately before the start of the high temperature process, the setting of α ′ is different from that of the previous embodiment. Unlike, α '> 1.0
Becomes When the low temperature level state is formed by pulse lighting as described above, there is an advantage that the accuracy of the laser power control at the low temperature level can be improved.

Further, in the embodiment, as a method for obtaining the power level PHth immediately before the start of the high temperature process, it was explained that an 8T continuous pattern was recorded and the recording power at which the reproduction signal amplitude rises was obtained as PHth. The mark portion of the 8T continuous signal may be illuminated with a pulse having a length of 1 / 2T. In this case, the PL level obtained from the PHth value is PL = β × PHth, and the coefficient β at this time is β <1.0. Furthermore, in the embodiments, (1-7) modulation has been described as an example, but it goes without saying that the present invention can be applied to other modulation methods.

[0047]

As described above, the present invention has the following effects. (1) By detecting the power level immediately before the start of the high temperature level state of the recording medium and determining the power level forming the low temperature level state and the power level forming the high temperature level state based on the detected power level, the temperature change in the apparatus can be prevented. Accordingly, it becomes possible to set the recording power to the optimum power level, regardless of temperature changes, dirt on the objective lens, medium, etc.
Recording pits can be recorded stably. (2) Using a relational expression between a power level forming a low temperature level state and a power level forming a high temperature level state, and calculating a power level forming a high temperature level state by changing a predetermined constant of this relational expression. Since the optimum power level is determined by recording the signal on the recording medium with the specified power level, the power level that forms the high temperature level state can be accurately adjusted to the optimum value, and accurate recording from the shortest pit to the longest pit is possible. it can. (3) Therefore, it is possible to accurately record the recording pits regardless of the temperature change in the device and the contamination of the medium, and it is possible to record information with a small amount of jitter, and to increase the speed and density of information recording. Can also respond.

[Brief description of drawings]

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

FIG. 2 is a diagram showing a laser lighting waveform when recording the 4T pattern of the embodiment of FIG.

FIG. 3 is a diagram showing a recording pattern and a laser lighting waveform in the embodiment of FIG. 1 in association with each other.

FIG. 4 is a flowchart showing an embodiment of the write test method of the present invention.

FIG. 5 is a diagram for explaining a method for obtaining a laser power level PHth immediately before the high temperature level state of the magneto-optical disk starts.

FIG. 6 is a diagram showing a relationship between a thermal diffusion constant and PH1 and PH2.

FIG. 7 is a diagram showing a relationship between a difference ΔSL in slice level between reproduction signals of an 8T continuous pattern and a 2T continuous pattern and PH1.

FIG. 8: 8T continuous, 2 due to the difference in the values of PH1 and PH2
It is the figure which showed the reproduction signal of T continuous pattern.

FIG. 9 is a diagram showing a result of a confirmation test of a light test.

FIG. 10 is a diagram showing the relationship between the radial position (linear velocity) of the disc and the recording power.

FIG. 11 is a diagram showing another example of a laser lighting waveform of a 4T pattern.

FIG. 12 is a diagram showing a conventional magneto-optical disk device.

[Explanation of symbols]

 1 Magneto-optical disk 3 Spindle motor 4 Optical head 5 Semiconductor laser 8 Objective lens 11, 16 Optical sensor 12 AT / AF circuit 13 Bias magnet 14 Objective lens actuator 17 Amplitude detection circuit 18 CPU 19 Asymmetry detection circuit 20 Semiconductor laser drive circuit

Claims (5)

[Claims] 1. When recording information on an information recording medium by controlling the recording power of a light source by multi-valued control, a write test is performed on the recording medium to set the multi-valued recording power of the light source to an optimum value. A write test method for adjusting, wherein a predetermined signal is recorded on the recording medium while changing the recording power, and a power level immediately before a high temperature level state of the recording medium starts is detected based on the reproduced signal amplitude. And a step of determining a power level for forming a low temperature level state on the recording medium based on the obtained power level, and a relational expression between the power level for forming the low temperature level state and the power level for forming a high temperature level state. And the predetermined constant of this relational expression is changed to calculate the power level forming the high temperature level state, and at the obtained power level, Recording signals of different lengths on a recording medium, and determining a power level for forming a high temperature level state based on a difference between a peak value and a bottom value of a reproduction signal of the signals of different lengths. A light test method characterized in that 2. The write test method according to claim 1, wherein the power level forming the low temperature level state is:
The write test method is characterized in that it is determined by multiplying a power level immediately before the high temperature level starts by a predetermined coefficient. 3. The write test method according to claim 1, wherein the predetermined constant is a thermal diffusion constant determined by a thermal characteristic and a linear velocity of the recording medium. 4. The write test method according to claim 1, wherein the relational expressions form a power level forming the low temperature level state, a first power level forming a high temperature level state, and a high temperature level state. A relational expression representing a relation with a second power level, wherein the first power level and the second power level forming the high temperature level state are calculated by performing an arithmetic operation using the relational expression. Characteristic light test method. 5. An optical information recording / reproducing apparatus for recording information by controlling the recording power of a light source on an optical information recording medium by multi-valued control, and recording a predetermined signal on the recording medium while changing the recording power. And a means for detecting the power level immediately before the high temperature level state of the recording medium starts based on the reproduced signal amplitude, and a power level for forming the low temperature level state on the recording medium based on the obtained power level. A means for determining, and a relational expression of the power level forming the low temperature level state and the power level forming the high temperature level state are used, and the power level forming the high temperature level state is changed by changing a predetermined constant of the relational expression. Means for calculating, a signal having a different length is recorded on the recording medium at the calculated power level, and a peak value and a bottom of a reproduction signal of the signal having a different length. And a means for determining a power level forming a high temperature level state based on a difference between intermediate values.