JPH08306052A - Optical disk device - Google Patents

Abstract

PURPOSE: To widen a margin of a recording power having a small error rate by an inexpensive and a simple constitution at the time of recording at high temp. inside a device. CONSTITUTION: An optical disk device 1 performs information recording by making a later diode 6 to emit a pulse beam by means of a LD driver 7 and irradiating a recording medium 2 with a light beam. At this time, temp. in the vicinity of the surface of the recording medium is detected by means of a temp. sensor 12, a CPU 11 sends a focus offset setting signal to a focusing actuator driver 13 when the recording medium is at high temp. based on the detected result of temp., an offset current is superimposed on a focusing servo driving current supplied to a focusing actuator 5 and the condition of convergence of a laser beam is controlled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk device for optically recording information on a disk-shaped recording medium.

[0002]

2. Description of the Related Art In recent years, various optical disk devices have been developed for optically recording and reproducing information on a disk-shaped recording medium. As an example of the optical disk device, the following description will be given here using a device using a magneto-optical disk as a recording medium.

At present, the magneto-optical disk has a size of 130 mm and 60 mm.
0 / 650MB disc (ISO / IEC1008
9), 1.2 / 1.3 GB disc (ISO / IEC1
3549), 90mm 128MB disc (I
SO / IEC10090), 230MB disk (EC
MA / TC31 / 93/90), a total of four types of magneto-optical discs have been standardized.
Drive devices capable of recording and reproducing information on or from various types of discs have been put on the market.

In a magneto-optical disk drive device, an external magnetic field is applied to a magnetic thin film having a perpendicular magnetic anisotropy formed on a substrate of a magneto-optical disk, and a laser beam is pulsed to emit a temperature of a recording portion. To the Curie point,
Information signals are recorded (hereinafter referred to as magneto-optical recording) by changing the direction of the magnetic field of the recording unit.

As described above, in the magneto-optical disk drive device, magneto-optical recording is performed by raising the temperature of the magnetic thin film. Therefore, in order to perform good recording with few errors during reproduction, recording conditions such as the medium and the surrounding environment are required. Along with the change of, the temperature rise area is changed to an appropriate recording area (hereinafter referred to as pit)
Needs to be generated.

For example, a so-called CAV system (130 mm 600/650 MB, which has a constant recording density in the circumferential direction,
Alternatively, in the case of a 90 mm (128 MB) disc, the recording density is higher at the inner circumference of the portion where information is recorded than at the outer circumference. For this reason, if recording is performed over the entire circumference with the same power and the same pulse width, the area of the pit becomes smaller on the inner circumference than on the outer circumference, so that the area wider than the area actually being recorded is heated and the magnetic domain direction is changed. As a result, a so-called error component is increased because it is superimposed as a jitter component.

As a method for solving this problem, there is a recording method disclosed in JP-A-59-24452. This is because the pulse width control circuit is provided in the optical disc device in order to optimally record the signal in the CAV type disc, so that the irradiation pulse width of the recording laser beam (hereinafter referred to as the recording pulse width) is adjusted at the inner and outer circumferences. To change.

However, in recent years, a so-called ZCAV system device has been put into practical use, which is capable of high density recording by reducing the pit interval on the entire surface of the disk, in contrast to the CAV system. ZCAV type disc (130mm
1.2 / 1.3 GB or 90 mm 230 MB), a plurality of annular regions of the same recording angular velocity (hereinafter referred to as bands) are provided in the radial direction of the disc, and the reference channel clock length ( 1T below
Abbreviated) to achieve higher density recording.

In recording information using such a ZCAV type disc, since the 1T differs between bands, it is necessary to change the recording pulse width accordingly. Further, even within the same band, it is necessary to finely adjust the recording pulse width with respect to 1T in order to correct the error rate as described above. At the time of this correction, it is necessary to generate a plurality of types of pulses (the number of bands + α) by the pulse width control circuit, so that there is a problem that the burden on the hardware configuration is large and the device cost is increased.

As a solution to this problem, there is an apparatus disclosed in Japanese Patent Laid-Open No. 7-44867. In this apparatus, in order to generate a plurality of types of recording pulse widths, a multiplying circuit that performs multiplication with 1T as a reference is provided to generate a pulse width of 0.75T or 0.825T, for example. With this multiplier circuit, the hardware configuration for generating a plurality of types of pulses can be simplified and the device cost can be reduced.

[0011]

However, none of the above-mentioned conventional devices considers the influence of the temperature change of the medium. As mentioned above, since magneto-optical recording is performed by the temperature rise of the magnetic thin film,
A change occurs in a pit (a magnetic domain region in which the magnetization is directed to the recording side) on the magneto-optical medium, and an error rate increase as a jitter component due to a temperature difference is also superimposed.

The effect of the temperature change is that the recording amplitude of the shortest recording pulse pattern (for example, 3T recording pattern in 2-7 modulation recording) between the optical disk devices and the longest recording pulse pattern (for example, 2-7 modulation recording in the 2-7 modulation recording). (8T recording pattern) and the recording amplitude (this is also referred to as MTF hereinafter as a number representing the attenuation rate of the recording amplitude of the shortest recording pulse pattern).

In the optical disk device, the HF module itself or the variation of the pulsed light due to the variation of the matching between the laser and the HF module, the aberration, the variation of the laser spot on the medium surface due to the variation of the spread angle of the laser beam, Due to various factors such as variation due to polarization ratio, measurement error due to measurement system, and variation due to electrical system, the MTF value varies among the individual devices.

Of these, the main cause is MT due to variations in laser spots (variations in focusing of laser spots).
Consider the change in F value. Longest recording pulse pattern (8T recording pattern) and shortest recording pulse pattern (3
FIG. 4 shows changes in recording amplitude due to changes in recording power in each of the T recording patterns.

In the longest recording pulse pattern ((a) and (b) of FIG. 4), the recording amplitude increases as the recording power increases, but the shortest recording pulse pattern ((c) and (d) of FIG. 4). , The resolution between recording pulses decreases due to the increase in recording power, and the recording amplitude does not increase at the same rate as the longest recording pulse pattern.

When the laser spot diameter is narrowed down sufficiently, the temperature rise occurs in a wide area around the pit to be recorded, compared with the case where the laser spot diameter is not narrowed down. The decrease becomes significant and the MTF decreases. Therefore, when the recording power on the medium is unified among the individual devices, the MTF is minimized, that is, the laser spot is well focused and the resolution of the recording amplitude of the shortest recording pulse pattern is increased by increasing the recording power. The product with the lowest drop (hereinafter abbreviated as the MTF lower limit product) and the product with the maximum MTF, that is, the laser spot focusing is poor and the resolution of the recording amplitude of the shortest recording pulse pattern does not decrease the most due to the increase of the recording power ( Hereafter, it is necessary to set the recording power so that the error rate at the time of reading is sufficiently low for both the MTF upper limit product.

When recording on the medium with the MTF upper limit product, since the beam spot by the laser beam is not sufficiently narrowed down, the recording power for starting the formation of pits with a small error rate becomes larger than the MTF lower limit product. Also MT
When recording on the medium with the F lower limit product, the resolution between pits becomes poor, and the error rate begins to decrease with a recording power lower than that of the MTF upper limit product.

FIG. 5 shows the relationship between the recording power and the error rate in each of the MTF upper limit product and the MTF lower limit product. In FIG. 5, the horizontal axis represents the change in recording power, and the vertical axis represents the temporal margin of the data pulse in the data window (hereinafter, abbreviated as phase margin) for each of the MTF upper limit product and the MTF lower limit product. It is a graph.

At this time, the recording power P required to obtain a margin above a certain phase margin value A is P1 at the rising intersection of the MTF upper limit product and P2 at the falling intersection of the MTF lower limit product with respect to A. If expressed, P1 ≤ P ≤ P2.

The relationship between the recording powers P1 and P2 and the temperature of the medium is shown in FIG. In FIG. 6, the upper straight line shows the temperature change of P2, and the lower broken line shows the temperature change of P1, and the area between the upper and lower straight lines has a certain phase margin value A or more. This is the area of the obtained recording power P.

As a general tendency of this temperature characteristic line,
The upper straight line (P2 temperature change straight line) corresponding to the MTF lower limit product with good laser spot focusing has a steeper slope than the lower straight line (P1 temperature change straight line) corresponding to the MTF upper limit product. It will be As a result, P1 and P at high temperature
The difference between 2 (ΔPb) is the difference between P1 and P2 at low temperature (ΔPa)
It gets smaller. Therefore, when the temperature is high, the recording power area where a margin equal to or more than the constant phase margin value A is obtained becomes narrower at the time of low temperature, and the margin is narrower against the power change due to the abnormality of the optical disk device.

In order to solve this problem, a method of changing the pulse width to a short pulse width at a high temperature by a pulse width control circuit can be considered, but such a structure has a problem that the cost becomes high as described above.

The present invention has been made in view of the above circumstances, and in recording when the temperature inside the apparatus is high, an optical disk apparatus capable of widening a recording power margin with a low error rate by an inexpensive and simple structure. Is intended to provide.

[0024]

An optical disk device according to the present invention has an optical system for converging laser light on a recording portion formed on a disk-shaped recording medium, and performs optical pulse emission of the laser light. Optical recording means for recording information, medium temperature detecting means for detecting the temperature of the recording medium, and when performing the pulse emission, when the temperature of the recording medium rises based on the detection result of the medium temperature detecting means. A laser for superimposing an offset current on the focus servo drive current supplied to the optical system of the optical recording means according to the change in the recording power with respect to the recording medium accompanying this temperature rise, and controlling the focused state of the laser light. And spot control means.

[0025]

When the optical recording means emits pulsed laser light to record optical information, the laser spot control means raises the temperature of the recording medium based on the temperature detection result of the recording medium by the medium temperature detecting means. In this case, an offset current is superposed on the focus servo drive current supplied to the optical system of the optical recording means in accordance with the change in the recording power with respect to the recording medium due to this temperature rise, and the focused state of the laser light is controlled. To do. As a result, the size of the recording pattern recorded on the recording medium becomes a desired size according to the temperature of the recording medium, and the range of the recording power at which the error rate is lower than the allowable amount is widened.

[0026]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 relate to a first embodiment of the present invention.
2 is a configuration explanatory view showing a configuration of a main part of the optical disc device, and FIG. 2 is a characteristic diagram showing a temperature change of recording power in the optical disc device of the present embodiment.

In this embodiment, an example of the structure of an optical disk device having a recording / reproducing head of a separate optical system and recording / reproducing on / from a recording medium such as a magneto-optical disk will be described.

The optical disk device 1 has an optical head 3 which is arranged so as to face one surface of a recording medium 2, and a laser diode (LD) 6 for generating a laser beam is controlled by an LD driver 7 to drive the laser diode (LD) 6. By pulsed light emission or continuous light emission, a recording or reproducing light beam is irradiated through the optical head 3 to write and read information on the recording medium 2.

The optical head 3 is provided with a light receiving element 22 for detecting the reflected light from the recording medium 2. The light beam reflected from the recording medium 2 is received by the light receiving element 22 through the optical system of the optical head 3. And is detected as optical information. Further, the optical head 3 is provided with a track actuator 4 and a focus actuator 5 for performing tracking control and focus control. The track actuator 4 and the focus actuator 5 are respectively arranged so that the tracking and focusing servos follow the track error signal and the focus error signal obtained from the reflected light from the recording medium 2 detected by the light receiving element 22. It is adapted to be driven by drive signals from the driver 14 for focus and the driver 13 for focus actuator.

The optical disk device 1 is provided with a CPU 11 for controlling the entire device, and a SCSI (Small Computer)
System Interface) Interface (I / F) 15
It is connected to the host computer 16 of the higher order via. A temperature sensor 12 having a sensor unit for detecting the temperature near the medium surface of the recording medium 2 is arranged near the recording medium 2 inside the optical disc device 1. The data is sent to the CPU 11.

A recording pulse generating circuit 8 for generating a recording pulse for writing information is provided and is connected to the LD driver 7 via an APC circuit 21 for controlling output. The recording pulse generating circuit 8 includes a recording data pattern generating circuit 9 and a reference clock generating circuit 10.

When recording information on the medium surface of the recording medium 2, the reference clock generating circuit 10 reads the VFO area preformatted on the recording medium 2 by the optical head 3 and obtains the VFO signal. Is received from the CPU 11 and a reference clock is generated in synchronization with the frequency of the VFO signal. Further, the recording data pattern generation circuit 9 has
Along with the reference clock, the recording data transmitted from the host computer 16 to the CPU 11 via the SCSI interface 15 undergoes code modulation (2-7 modulation, 1-7 modulation, etc.) suitable for optical recording in the CPU 11, and a recording data pattern. Is entered as.

The recording data pattern generation circuit 9 receives the reference clock generated by the reference clock generation circuit 10, synchronizes the recording data pattern received from the CPU 11 with the reference clock, and generates a recording signal. This recording signal is sent to the APC circuit 21 under the control of the CPU 11.
Is adjusted to an appropriate recording power and supplied to the LD driver 7, and the laser diode 6 is driven by the LD driver 7. As a result, the laser diode 6 emits a pulsed light with an appropriate recording power to irradiate the recording light beam onto the medium surface of the recording medium 2 to record information.

In the subsequent stage of the light receiving element 22 of the optical head 3, a reproduction amplifier 23 for reproducing information, a waveform equalizer 24, a shaper 25, a PLL 26, a discriminator 27, and a decoder 2 are provided.
8 is provided, and the decrypted reproduction data is sent to the CPU 11.

When the information recorded on the medium surface of the recording medium 2 is reproduced, under the control of the CPU 11, the laser diode 6 is made to continuously emit light with an appropriate reproduction power to record a reproduction light beam. The light is irradiated onto the medium surface of the medium 2, and the reflected light from the recording medium 2 is received by the light receiving element 22 of the optical head 3 to obtain a reproduction signal.

The reproduced signal is amplified by the reproducing amplifier 23, passes through the waveform equalizer 24, is shaped by the shaper 25, and is input to the PLL 26 and the discriminator 27.
In addition, the synchronization signal output from the PLL 26 is the discriminator 27.
And a discriminator 27 generates a detection code string from the reproduction signal and the synchronization signal. And the decoder 2
A data bit string indicating reproduction information is decoded from the detection code string by 8 and sent to the CPU 11.

Next, detailed operation of the optical disc apparatus 1 of this embodiment at the time of recording information will be described.

The CPU 11 determines the peak power of the pulse of the recording data pattern (hereinafter referred to as recording pulse) based on the temperature detection result of the temperature sensor 12 near the medium surface, that is, the temperature of the recording film of the recording medium 2 is high or low. The time (hereinafter referred to as the rise time) until reaching (1) is adjusted to adjust the recording power margin capable of forming a pit of a desired size with a small error rate.

When the temperature is low, a normal recording pulse, that is, a recording pulse whose rising time is not lengthened, is used for recording. On the other hand, when the temperature is high, the margin of the recording power at which the optical recording is optimally performed becomes wider than that of the normal recording pulse.
The rise time of the recording pulse is delayed.

In this embodiment, as a means for adjusting the margin of the recording power, the CPU 11 sends a focus offset setting signal to the focus actuator driver 13 to offset the focus servo drive current supplied to the focus actuator 5. By superimposing an electric current, the focus point of the laser spot is shifted from the just focus position on the medium surface, and the temperature rise of the medium is delayed by deteriorating the focusing and intentionally reducing the temperature rise region by the laser light. As a result, the rise time of the recording pulse is delayed.

The relationship between the recording power and the temperature of the medium in this embodiment is shown in FIG. In FIG. 2, the rising intersection of the MTF upper limit product and the falling intersection of the MTF lower limit product with respect to a certain phase margin value A as shown in FIG. 5 are P1 and P2.
As shown in FIG. 6, the temperature change of the recording power is shown. Here, the recording power when the offset current is superimposed on P1 and P2 is shown by P1 'and P2'. The region sandwiched by the temperature change straight lines P1 and P2 and P1 'and P2' is the region of the recording power P in which a margin of a certain phase margin value A or more can be obtained.

When the focusing of the laser spot is made worse, the recording power for forming the pits is shifted in parallel to the higher side as much as the focusing becomes worse. However, as compared with the shift amount of the temperature change straight line of P1 which originally has poor light collection, the shift amount increases in the temperature change straight line of P2 which has good light collection and the shift amount increases, and as a result, it is allowed. Increases power range. That is, the difference between P1 and P2 at high temperature is .DELTA.Pb, the difference between P1 'and P2' is .DELTA.Pb ', the difference between P1 and P2 at low temperature is .DELTA.Pa, and the difference between P1' and P2 'is .DELTA.Pa.
′, ΔPa <ΔPa ′ and ΔPb <ΔPb ′.

However, due to the balance with the emission limit power of the laser used as shown in FIG. 2, the margin of the recording power obtained by using the means for delaying the rise time of the recording pulse of this embodiment at a low temperature. Is not so large, the effect of widening the margin of the recording power with a small error rate can be obtained mainly at high temperatures.

When adjusting the recording power margin in this way, the relationship between the defocus amount of the recording pulse and the phase margin is measured in advance in accordance with the temperature change, and is compared with the temperature change of the phase margin in the normal state. Then, the defocus amount that gives the maximum recording power margin is set at the time of information recording. As a result, the error rate of the recorded pits can be minimized even when the recording power is slightly changed due to the abnormality of the optical disk device, for example, the dust adhered to the objective lens and the recording power is lowered. it can.

As described above, according to this embodiment, the following effects can be obtained.

First, although the upper and lower limits of the recording power with a small error rate are narrowed and the margin is reduced due to the temperature rise of the optical disc medium, the margin of the recording power is reduced by superimposing the offset current on the focus servo drive current. Even if the recording power fluctuates due to an abnormality in the optical disk device, pits with a low error rate can be formed.

Second, since the margin of the recording power having a low error rate can be widened at a high temperature without changing the pulse width of the recording pulse from the reference channel clock length (reference clock period), the pulse width control circuit. It is not necessary to provide the above, and the circuit configuration is simple with a small amount and can be implemented at low cost.

Next, a second embodiment of this embodiment will be described. FIG. 3 is a configuration explanatory view showing a configuration of a main part of the optical disc apparatus according to the second embodiment.

When recording information on the recording medium, the power is changed in advance to set the optimum recording power,
Even in the case of so-called trial writing, by using the configuration of this embodiment described above, it is possible to set a wide range of the recording power area having a low error rate at a high temperature.

In the second embodiment, an example of the structure of an optical disk device having the means for performing the trial writing will be described.

The optical disk device 31 of the second embodiment is shown in FIG.
The reproducing system is changed in the configuration of the first embodiment shown in FIG. The configuration of the other parts is similar to that of the first embodiment, and the same components are designated by the same reference numerals and the description thereof is omitted.

In the optical disk device 31, the reproduction signal directly output from the reproduction amplifier 23 and the waveform equalizer 2 are provided in the subsequent stage of the reproduction amplifier 23 during the trial writing and the normal operation.
An input switch 42 is provided for switching between the signal passed through the input terminal 4. Further, in the subsequent stage of the discriminator 27, a comparison discriminator 43 for comparing the difference between the trial writing pattern sent from the CPU 41 to the recording data pattern generation circuit 9 and the detection code string output from the discriminator 27 is provided. There is.

The recording of information on the recording medium 2 is performed in the same manner as in the first embodiment, but at the time of trial writing, the recording power is gradually changed from the CPU 41 to the APC circuit 21 for recording. An instruction of trial writing power is sent.

During reproduction of information, the reflected light from the recording medium 2 passes through the optical head 3, is guided to the light receiving element 22, is received, and is converted into a reproduced signal. This reproduction signal is amplified by the reproduction amplifier 23 and then divided into two, one to the direct input switch 42 and the other to the waveform equalizer 2.
It is input to the input switch 42 via 4 respectively. At the time of executing the trial writing, the signal is switched by the input switch 42 so that the signal directly output from the reproduction amplifier 23 is output to the shaper 25 in the subsequent stage.

The output signal from the input switch 42 is shaped into a waveform by the shaper 25 and is input to the PLL 26 and the discriminator 27. Further, the synchronizing signal output from the PLL 26 is input to the discriminator 27, and the discriminator 27 generates a detection code string from the reproduction signal and the synchronizing signal. Then, the decoder 28 decodes the data bit string indicating the reproduction information from the detection code string and sends it to the CPU 41.

Further, the detection code string generated by the discriminator 27 is also sent to the comparison / determination unit 43. The comparison discriminator 43 is C
The trial writing pattern sent from the PU 41 to the recording data pattern generation circuit 9 is input, and the difference from the detection code string output from the discriminator 27 is compared. Based on the comparison result, the CPU 41 sets the recording power value so that the difference between the recording code string and the reproducing code string is minimized.

At this time, the CPU 11 causes the temperature sensor 12 to
Based on the temperature detection result in the vicinity of the medium surface by the recording medium 2
Trial writing is performed while changing the rise time of the recording pulse depending on the temperature.

When the temperature detection result in the vicinity of the medium surface is low, the test writing is performed only by changing the recording power.
On the other hand, if the temperature detection result near the medium surface is high,
When performing test writing, the CPU 41 sends a focus offset setting signal to the focus actuator driver 13 to change the test writing power while changing the offset current superimposed on the focus servo drive current.

At this time, the area of the recording power with a low error rate changes due to the change of the focus offset current, but the area with the widest recording power area is stored in the CPU 41 as the focus offset value of the optimum recording pulse. . Further, the central value of the area is stored in the CPU 41 as the optimum recording power.

When recording on the recording medium 2, the CPU 41 sets the focus offset value and recording power.
More focus actuator driver 13 and AP
Instruct the C circuit 21.

When the focus offset value and the recording power are set as described above and the offset current is superimposed on the focus servo drive current when the recording medium is at a high temperature, when recording is performed for a long time after the trial writing is completed, for example, the entire format is used. Even when an abnormality occurs in the optical disk device and the recording power is changed, for example, the error rate of the recorded pits can be minimized.

Since there is some error in the optimum recording power obtained by the trial writing, a wide power margin is required. The configuration of the present embodiment can widen the area in which the recording power can be set at a high temperature, and is therefore effective in an apparatus for performing such trial writing.

As described above, according to the present embodiment, in addition to the effect of the first embodiment, it is possible to set the recording power area having a low error rate to the widest range in the trial writing at a high temperature. Even in the state where trial writing cannot be performed due to long-time recording or the like, it is possible to obtain the effect that the error rate of the recording pit can be minimized with respect to the change in recording power.

As described in the above embodiments, in the present embodiment, the margin can be widened in the state where the recording power margin of the optical disc device is reduced due to the temperature change of the recording medium, and the recording of the optical disc device is performed. A recording pulse with a low error rate can be recorded on the medium surface regardless of the change in power. In addition, since a special circuit such as a pulse width control circuit for controlling a plurality of pulse widths is not required in the structure for expanding the margin of the recording power, the device structure can be simple and inexpensive.

[0065]

As described above, according to the present invention, in recording when the temperature inside the apparatus is high, it is possible to widen the margin of the recording power with a low error rate by an inexpensive and simple structure. is there.

[Brief description of drawings]

FIG. 1 is a configuration explanatory view showing a configuration of a main part of an optical disc device according to a first embodiment of the invention.

FIG. 2 is a characteristic diagram showing the temperature change of the recording power in the optical disc device of the present embodiment.

FIG. 3 is a configuration explanatory view showing a configuration of a main part of an optical disc device according to a second embodiment of the invention.

FIG. 4 is an operation explanatory view showing a change in recording amplitude due to a change in recording power in each of the longest recording pulse pattern and the shortest recording pulse pattern.

FIG. 5 is a characteristic diagram showing the relationship between the recording power and the error rate in each of the MTF upper limit product and the MTF lower limit product.

FIG. 6 is a characteristic diagram showing the relationship between the recording power and the temperature of the medium in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Optical disk device 2 ... Recording medium 3 ... Optical head 5 ... Focus actuator 6 ... Laser diode (LD) 7 ... LD driver 8 ... Recording pulse generation circuit 11 ... CPU 12 ... Temperature sensor 13 ... Focus actuator driver 21 ... APC circuit

Claims (3)

[Claims] 1. An optical recording unit having an optical system for converging a laser beam on a recording section formed on a disc-shaped recording medium, for recording optical information by performing pulse emission of the laser beam. A medium temperature detecting means for detecting the temperature of the medium, and when performing the pulsed light emission, based on the detection result of the medium temperature detecting means, when the temperature of the recording medium rises, the recording power of the recording power with respect to the recording medium is increased. A laser spot control means for controlling a focusing state of the laser light by superposing an offset current on a focus servo drive current supplied to an optical system of the optical recording means according to a change. Optical disk device. 2. The optical disk device according to claim 1, wherein the optical recording means sets the pulse width to the same length as the period of the reference clock when performing the pulse emission. 3. The optical recording means includes means for performing trial writing for changing the recording power to perform recording and setting an optimum recording power value, and the laser spot control means for performing the trial writing. 2. The optical disk device according to claim 1, wherein an optimum value of the offset current is set, and the optimum value of the offset current is superimposed on the focus servo drive current when the temperature of the recording medium is high.