JP2004005927A - Method for controlling laser power in optical disk recorder/player, and optical disk recorder/player - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent deterioration in the quality and reliability of written data due to a change in temperature by detecting a temperature in the vicinity of a laser diode when a linear velocity changes and correcting the temperature with laser power with the temperature taken into consideration in the case of writing data to an optical disk by a zone CLV (constant linear velocity) method. <P>SOLUTION: In a control method for controlling laser power for writing of an optical disk recorder/player 30 controlled by the zone CLV method that can write data, making a linear velocity in writing higher stepwise as the data are written toward the outer circumferential side of an optical disk 10, the temperature in the vicinity of the laser diode 12 that emits laser beams is detected when the linear velocity in writing is changed, and laser power after the linear velocity in writing is changed is controlled so as to correspond to the detected temperature in the vicinity of the laser diode 12 and to change as much as a correction value corresponding to a new linear velocity after the linear velocity is changed. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a laser writing output control method of an optical disk recording / reproducing apparatus capable of recording data on an optical disk such as a CD-R or a CD-RW, and an optical disk recording / reproducing apparatus.
[0002]
[Prior art]
As an optical disk recording / reproducing device for recording data on an optical disk, a CD-R (Compact Disc-Recordable) device and a CD-RW (Compact Disc-Rewritable) device are known.
[0003]
When writing data to an optical disc, the rotation of the optical disc is controlled by a so-called CLV (Constant Liner Velocity) method in which the linear velocity of writing is kept constant so that the density of the written pits is kept constant. I have been. In the CLV method, in order to keep the linear velocity constant, the rotation speed increases when writing on the inner circumference side of the optical disc, and decreases as it moves toward the outer circumference side of the optical disc.
On the other hand, in recent optical disk recording / reproducing apparatuses, it is desired that data be written to the optical disk at a higher speed than in the past. The rotation speed becomes too high, and there is a problem that data cannot be reliably written on the inner peripheral side.
[0004]
Therefore, an optical disk recording / reproducing apparatus controlled by a zone CLV control method has been developed in order to shorten the writing time of the entire optical disk without increasing the rotation speed on the inner peripheral side of the optical disk and increase the writing speed as a whole.
In the zone CLV method, writing is performed at a constant low linear velocity on the inner peripheral side of the optical disk. Therefore, the rotational speed on the inner peripheral side is the same as that in the related art. This is a method of increasing the speed and increasing the rotation speed to increase the writing speed of the entire optical disc.
[0005]
FIG. 5 shows an example of data writing by the zone CLV method.
In this example, writing is performed at 16 × speed on the inner circumference side of the optical disc 10, writing is performed at 20 × speed when moving to the outer circumference after elapse of a predetermined time, and writing is performed at 24 × speed after moving to the outer circumference after elapse of the predetermined time.
By adopting the zone CLV method, the inner peripheral side of the optical disk 10 rotates at the conventional rotational speed, so that no writing error occurs on the inner peripheral side, and the writing speed can be increased as a whole.
[0006]
Note that the optical disk recording / reproducing apparatus performs a data writing test (so-called OPC (Optimum Power Control)) in a PCA (see reference numeral 9 in FIG. 5) located at the innermost periphery of the recording surface of the optical disk when writing data to the optical disk. And the power of the laser beam at the time of writing is set to an appropriate value.
Hereinafter, the power setting of the laser beam in the optical disk recording / reproducing apparatus will be described.
The optical disk recording / reproducing device first reads the ATIP from the optical disk. ATIP is where optical disk manufacturers record optical disk information such as optical disk product names.
The optical disk recording / reproducing apparatus reads a recommended laser power value from a preset data table based on the optical disk information, and performs test writing by increasing and decreasing the power of the laser light around the read recommended laser power value. Do. The test-written data is read, and the vertical contrast (asymmetry) of the read light intensity waveform is confirmed. By confirming the vertical contrast, the laser power at the time of the best vertical contrast is set as the optimum laser power value of the optical disc.
[0007]
[Problems to be solved by the invention]
As described above, in the optical disc recording / reproducing apparatus, the OPC is performed in the innermost PCA of the optical disc to set the optimum value of the laser power.
However, in the optical disk recording / reproducing apparatus adopting the zone CLV method, the linear velocity is increased on the outer peripheral side of the optical disk. There is a problem that it cannot be said that it is.
That is, in the example shown in FIG. 5, the laser power value was set at 16 times speed in the case of OPC, but when writing reached the outer circumference of the optical disk, the linear speed became 20 times speed or 24 times speed, The optimum laser power value is different from the case where the laser speed is set at 16 times speed, and the higher the linear velocity, the more power is required.
[0008]
In such a case, even if the laser power deviates from the optimum laser power, it is not so large that writing cannot be performed. Therefore, it is possible to continue writing without changing the laser power as it is.
However, since writing is not performed with the optimum laser power, the quality and reliability of the written data may be reduced, for example, the data cannot be read when the written data is read.
[0009]
Therefore, the present inventors consider that when controlling by the zone CLV system, the quality and reliability of the written data should be maintained by changing the laser power when the linear velocity is changed. Reached.
In this case, when changing the laser power, a correction value to be added to the power is set in advance so that the laser power after the linear velocity change becomes a suitable value, and the laser power is set to a value obtained by adding the correction value. It was considered that the laser diode should be controlled first.
[0010]
However, the laser diode has a characteristic that the output value varies depending on the temperature state even when the voltage value applied to the laser diode is constant. Furthermore, the wavelength of the laser light output from the laser diode changes depending on the temperature.
This change in the wavelength of the laser light is about 1 to 3 ° / deg (1 ° per 1 degree change in temperature) and has no significant effect such as inability to write data. There is a problem that the quality and reliability of written data may be reduced.
[0011]
Therefore, the present invention has been made to solve the above-described problem, and an object of the present invention is to detect a temperature near a laser diode when a linear velocity is changed when data is written to an optical disk by a zone CLV method. Control of laser writing output in an optical disc recording / reproducing device that can correct the laser power by using a value that takes temperature into account, and prevent the quality and reliability of written data from deteriorating due to a change in temperature. A method and an optical disk recording / reproducing apparatus are provided.
[0012]
[Means for Solving the Problems]
That is, according to the laser power control method of the optical disk recording / reproducing apparatus according to the present invention, the linear velocity at the time of writing is increased stepwise toward the outer peripheral side of the optical disk, and the control is performed by the zone CLV method in which writing is possible. A method for controlling a writing laser power of an optical disc recording / reproducing apparatus, comprising detecting a temperature near a laser diode for irradiating a laser beam when a linear velocity at the time of writing is changed, and Is controlled so that the laser power after the linear velocity has changed is changed by the correction value corresponding to the temperature near the detected laser diode and the new linear velocity after the linear velocity is changed. It is characterized by doing.
According to this method, when the linear velocity at the time of writing is changed, temperature compensation is performed in accordance with the temperature in the vicinity of the laser diode. It is possible to cope with a change in the wavelength and to prevent the quality and reliability of the written data from deteriorating even when high-speed writing is realized by the zone CLV method.
[0013]
Further, when the linear velocity at the time of writing is changed, the correction value is detected as a linear velocity correction value that is set in advance to correspond to a new linear velocity after the linear velocity is changed. It may be calculated by multiplying a preset temperature compensation coefficient to correspond to the temperature near the laser diode.
According to this, it is possible to accurately compensate for the temperature of the laser power.
[0014]
According to the optical disk recording / reproducing apparatus according to the present invention, in the optical disk recording / reproducing apparatus controlled by the zone CLV system in which the linear velocity at the time of writing is gradually increased toward the outer peripheral side of the optical disk to enable writing. A laser diode for irradiating a laser, a temperature detector for detecting a temperature near the laser diode, and a temperature near the laser diode detected by the temperature detector when the linear velocity at the time of writing is changed. And a laser control means for controlling so as to change the laser power at the time of writing by adding a correction value corresponding to a new linear velocity after the linear velocity is changed to the laser power at the time of writing. It is characterized by doing.
By adopting this configuration, the temperature detector detects the temperature in the vicinity of the laser diode in real time, and when the linear velocity is changed, the laser power is adjusted to the detected temperature and to the linear velocity after the change. Therefore, even when the writing time is reduced by the Z-CLV method, the quality and reliability of the written data can be prevented from deteriorating.
[0015]
The laser control means includes: first storage means for storing a linear velocity correction value set in advance to correspond to a new linear velocity after the linear velocity has been changed; and a detected laser diode. A second storage unit that stores a temperature compensation coefficient preset to correspond to a nearby temperature, and a linear velocity correction value extracted from the first storage unit, which is extracted from the second storage unit. Calculating means for multiplying the temperature compensation coefficient.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
First, FIG. 1 shows an explanatory diagram of an embodiment of an optical disk recording / reproducing device (hereinafter, may be simply referred to as an optical disk device), and the operation principle will be described.
FIG. 1 shows a graph in which the horizontal axis represents the writing time when writing data to one optical disk, and the vertical axis represents the required laser power according to each speed when writing data.
As described in the related art, when data is written to the optical disk by the zone CLV method, the linear velocity is increased stepwise. In the present embodiment, for example, 16 ×, 20 ×, and 24 × speeds are used. The linear velocity is increased step by step so as to achieve.
[0017]
First, the laser power when writing at 16 × speed is a value P1 determined by OPC.
After a lapse of time t1 from the start of data writing, the linear velocity is switched to 20-times velocity. At this time, the laser power is also switched to the power adjusted to 20 times speed. It is assumed that the laser power adjusted to the 20-times speed is P2. The laser power P2 is obtained by adding the correction value A1 to the laser power P1 at 16 × speed.
Further, after a lapse of time t2 from the start of data writing, the linear velocity is switched to 24 times speed. At this time, the laser power is also switched to the power corresponding to the 24 × speed. It is assumed that the laser power at this time is P3. The switching of the laser power is performed such that a preset correction value A2 is added to the initial laser power P1.
[0018]
Here, the correction values A1 and A2 will be described.
Each correction value is a value to be added to the laser power of the laser that was irradiated before the linear velocity was changed in order to make the laser to be irradiated have an appropriate laser power for each linear velocity.
The correction values are linear velocity correction values a1, a2, b1, b2, c1, and c2 (described later), which are values merely corresponding to an increase in the linear velocity and do not take into account any temperature change. It is calculated from temperature compensation coefficients α1, α2, β1, β2, γ1, γ2, δ1, δ2 (described later) for slightly changing the linear velocity correction according to the temperature change.
[0019]
As a characteristic of a general laser diode, even when a set laser power is emitted at a high temperature, the write efficiency at room temperature is reduced due to wavelength fluctuation. On the other hand, at a low temperature, even when the laser power set in reverse is emitted, the write efficiency with respect to room temperature increases due to the wavelength fluctuation.
For this reason, according to the present invention, when the linear velocity at the time of the zone CLV control is changed, instead of always increasing the laser power by adding a constant correction value, it is preferable to add a correction value according to the temperature at that time. Thus, writing can be performed with a more appropriate laser power, and the quality of data written to an optical disk can be improved.
[0020]
Next, FIG. 2 shows a block diagram of the internal structure of the optical disk device, and the configuration of the device of the present embodiment will be described based on the block diagram.
The optical disk device 30 is a device that can write data on a CD-R or CD-RW as an example of an optical disk.
[0021]
The optical disc device 30 includes a laser diode 12 (hereinafter, sometimes simply referred to as an LD) that oscillates a laser beam for irradiating the optical disc 10 and a laser driver 14 that supplies a drive current for driving the LD 12 to the LD 12. It is built in. The LD 12 is built in the optical pickup 11 and moves from the inner peripheral side to the outer peripheral side of the optical disk 10 together with the optical pickup 11 to write data on the optical disk 10. The laser power of the LD 12 is controlled by current control by the laser driver 14.
[0022]
A thermistor 15 as an example of a temperature detector is provided near the LD 12 in the optical pickup 11. However, the temperature detector is not limited to a thermistor.
The temperature detector 15 measures the temperature near the LD 12 and sends a temperature detection signal to the CPU 24. Specifically, since the electrical resistance of the thermistor 15 changes according to the ambient temperature, the CPU 24 detects the temperature in the vicinity of the LD 12 by detecting the change in the voltage value applied to the thermistor 15.
[0023]
An APC (Auto Power Control) circuit 16 for controlling the voltage of the laser driver 14 is connected to the laser driver 14. The APC circuit 16 adjusts the voltage applied to the laser driver 14 so that a constant laser power is output so that the set laser power value does not fluctuate.
[0024]
Light reflected from the optical disk 10 is input to the RF amplifier 18 as a reflected signal via a detector (not shown) and is amplified.
The reflection signal from the optical disk 10 input to the RF amplifier 18 is input to the servo processor 20. The servo processor 20 performs servo control such as rotation of the spindle motor 22 and focusing and tracking of the optical pickup 11 based on the reflection signal.
[0025]
A storage means 26 such as a ROM is connected to the CPU 24. Data tables X and Y are constructed in the storage means 26.
The CPU 24 reads the data stored in the data tables X and Y, and can set the laser power at the time of OPC and change the laser power when the linear velocity is changed based on the data.
[0026]
The CPU 24 is a central processing unit that receives a reflection signal from the RF amplifier 18 and controls the APC circuit 16.
Here, the operation of the CPU 24 as described below is performed based on a control program, and such a control program is stored in advance in a memory (not shown) as firmware.
In the present embodiment, the APC circuit 16 and the CPU 24 constitute a laser control unit 28.
[0027]
The contents of the data table X will be described.
The contents of the data table X are set before shipment of the optical disk device 30. The data table X stores a recommended laser power P0 (Company A to each company) for the first OPC, corresponding to the type of the optical disc.
P0 is a laser power value used as a reference when performing OPC, and writing is not actually started with this value P0. Since the operation of the OPC has been described in the related art, the description is omitted here. However, in the OPC, a writing test is performed based on P0, and the laser power P1 at the time of actually writing is calculated.
Here, the value of P0 is shown only for different manufacturers, but it is obvious that the value of P0 differs depending on the type of optical disk even if the manufacturer is the same. However, FIG. 2 shows only each maker, and the case where the maker is the same but the type is different and the value of P0 is different is omitted.
[0028]
The data table X contains linear velocity correction values a1, b1, c1 added to the laser power P1 when the linear velocity is changed by the operation of the zone CLV, and the laser power P1 when the linear velocity is further changed. The linear velocity correction values a2, b2, and c2 to be added are set in advance corresponding to the type of each optical disc.
The linear velocity correction values a1, b1, and c1 are values to be added to the laser power P1 derived by OPC without considering the temperature environment when the linear velocity is changed from 16 × to 20 × for each optical disk maker.
The linear velocity correction values a2, b2, and c2 are values to be added to the laser power P1 derived by OPC without considering the temperature environment when the linear velocity is changed from 20 × to 24 × for each optical disk maker.
[0029]
Further, another data table Y is set in the storage means 26.
In the data table Y, the temperature compensation coefficients α1, α2, β1, β2, γ1, γ2, δ1, δ2 corresponding to the detected temperatures α to ε near the laser diode changed the linear velocity to 20 × and 24 ×. The case is set for each.
The temperature T in the vicinity of the laser diode is divided into four stages of α <T <β, β <T <γ, γ <T <δ, and γ <T <ε. Is set.
Although the data table Y is not set for each optical disk maker, it is assumed that the data table Y is set as a different numerical value for each optical disk maker similarly to the data table X.
Such linear velocity correction values and temperature compensation coefficients are set in advance and stored in data tables X and Y before shipment of the optical disk device.
[0030]
How the optical disk device 30 is controlled based on the contents of the data tables X and Y will be described with reference to the flowcharts of FIGS. Here, it is assumed that the optical disk is made by the company A shown in FIG.
First, in step S100, when the optical disk 10 is loaded to write data, the optical pickup 11 reads the ATIP previously written on the optical disk by the optical disk manufacturer.
The CPU 24 that has read the ATIP reads the recommended laser power value P0 corresponding to the type of the mounted optical disc recorded in the data table X.
The CPU 24 executes OPC based on the read value of P0, and sets a laser power value P1 when data is first written.
[0031]
In the next step S102, the CPU 24 starts writing data at the set laser power value P1.
Next, in step S104, if the speed is not changed, writing is continued with the laser power as it is, and if the speed is changed, the process proceeds to step S106.
[0032]
In step S106, the CPU 24 calculates a correction value to be added to the laser power.
Hereinafter, the correction value calculation will be described with reference to FIG.
First, in step S200, the thermistor 15, which is a temperature detector, detects the temperature near the laser diode, and the CPU 24 performs different control for each temperature detected in the next step S204.
That is, if the detected temperature T is α <T <β, the process proceeds from step S204 to step S212; if β <T <γ, the process proceeds from step S206 to step S214; if γ <T <δ, the process proceeds from step S208. If γ <T <ε, the process proceeds from step S210 to step S218.
[0033]
In step S212, the CPU 24 reads the temperature compensation coefficient α1 or α2 corresponding to the detected temperature α <T <β from the data table X, and multiplies the linear velocity correction value a1 or a2 read from the data table X in step S220.
In step S214, the CPU 24 reads the temperature compensation coefficient β1 or β2 corresponding to the detected temperature β <T <γ from the data table X, and multiplies the linear velocity correction value a1 or a2 read from the data table X in step S222.
In step S216, the CPU 24 reads the temperature compensation coefficient γ1 or γ2 corresponding to the detected temperature γ <T <δ from the data table X, and multiplies the linear velocity correction value a1 or a2 read from the data table X in step S224.
In step S218, the CPU 24 reads the temperature compensation coefficient δ1 or δ2 corresponding to the detected temperature δ <T <ε from the data table X, and multiplies the linear velocity correction value a1 or a2 read from the data table X in step S226.
In each of the steps S220 to S226, a correction value that is an actually added value obtained by multiplying the linear velocity correction value by the temperature compensation coefficient is calculated.
[0034]
When the correction value is calculated, the process returns to step S108 in the flowchart of FIG.
In step S108, the CPU 24 sets the laser power of the laser beam irradiated by the laser diode 12 based on the correction value calculated by the CPU 24 to a value obtained by adding the calculated correction value to the laser power before the linear velocity change. , APC circuit 16 to change the laser power.
[0035]
Then, in step S110, the process ends when all the data writing is completed.
[0036]
In the above-described embodiment, the storage unit that stores the linear velocity correction value and the temperature compensation coefficient in advance is the same storage unit. However, specifically, separate storage units may be used.
Further, in the above-described embodiment, the case where the linear velocity of the zone CLV is changed from 16 × to 20 × to 24 × is described. However, the change of the linear velocity is not limited to such numerical velocity. .
[0037]
Although various preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and it is a matter of course that many modifications can be made without departing from the spirit of the invention. .
[0038]
【The invention's effect】
According to the laser power control method in the optical disk recording / reproducing apparatus according to the present invention, when the linear velocity at the time of writing is changed, temperature compensation is performed in accordance with the temperature near the laser diode. Even when the laser power is used, it is possible to cope with the change in the wavelength of the laser beam due to the temperature, and even if high-speed writing is realized by the zone CLV method, the quality and reliability of the written data are not reduced. can do.
[0039]
According to the laser control method of claim 2, when the linear velocity at the time of writing is changed, the correction value is set in advance to correspond to a new linear velocity after the linear velocity is changed. The correction value is calculated by multiplying the correction value by a preset temperature compensation coefficient so as to correspond to the detected temperature in the vicinity of the laser diode, so that the laser power can be accurately compensated for the temperature.
[0040]
According to the optical disk recording / reproducing apparatus according to the present invention, the temperature detector detects the temperature near the laser diode in real time, and when the linear velocity is changed, it corresponds to the detected temperature and is adjusted to the changed linear velocity. Since the laser power can be used, the quality and reliability of the written data can be prevented from lowering even when the writing time is reduced by the zone CLV method.
[0041]
According to the optical disk recording / reproducing apparatus of the fourth aspect, the laser control means stores a linear velocity correction value set in advance to correspond to a new linear velocity after the linear velocity is changed. A storage unit, a second storage unit that stores a preset temperature compensation coefficient corresponding to the detected temperature near the laser diode, and a linear velocity correction value extracted from the first storage unit. Calculating means for multiplying the temperature compensation coefficient extracted from the second storage means. Therefore, the laser power can be changed with a more appropriate value between the linear velocity correction value and the temperature compensation coefficient.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram illustrating an operation of a recording / reproducing apparatus according to the present invention when a linear velocity is changed.
FIG. 2 is a block diagram illustrating a configuration of an optical disc recording / reproducing apparatus according to the present invention.
FIG. 3 is a flowchart illustrating a laser power control method of the optical disc recording / reproducing apparatus according to the present invention.
FIG. 4 is a flowchart illustrating correction value calculation.
FIG. 5 is an explanatory diagram illustrating a zone CLV method.
[Explanation of symbols]
9 PCA
DESCRIPTION OF SYMBOLS 10 Optical disk 11 Optical pickup 12 Laser diode 14 Laser driver 15 Temperature detector 16 APC circuit 18 RF amplifier 20 Servo processor 22 Spindle motor 26 Storage means 28 Laser control means 30 Optical disk recording / reproducing apparatus A1, A2 Correction value X, Y Data table a1 , A2, b1, b2, c1, c2 Linear velocity correction values α1, α2, β1, β2, γ1, γ2, δ1, δ2 Temperature compensation coefficient

Claims (4)

A control method for controlling a writing laser power of an optical disk recording / reproducing apparatus controlled by a zone CLV method in which the linear velocity at the time of writing is gradually increased toward the outer peripheral side of the optical disk to enable writing. hand,
When the linear velocity during writing is changed,
Detects the temperature near the laser diode that emits the laser light,
The laser power after the linear velocity at the time of writing is changed by an amount corresponding to the detected temperature near the laser diode and by the correction value corresponding to the new linear velocity after the linear velocity is changed. A laser power control method in an optical disk recording / reproducing apparatus, characterized in that the control is performed in the following manner. When the linear velocity at the time of writing is changed,
The correction value is
Calculated from a linear velocity correction value preset to correspond to a new linear velocity after the linear velocity is changed, and a temperature compensation coefficient preset to correspond to the detected temperature near the laser diode. 2. The laser power control method in an optical disk recording / reproducing apparatus according to claim 1, wherein In an optical disc recording / reproducing apparatus controlled by a zone CLV system in which the linear velocity at the time of writing is increased stepwise toward the outer peripheral side of the optical disc to enable writing,
A laser diode for irradiating a laser,
A temperature detector for detecting a temperature near the laser diode;
When the linear velocity at the time of writing is changed, the laser power after the linear velocity at the time of writing is changed corresponds to the temperature near the laser diode detected by the temperature detector, and the linear velocity is changed. An optical disk recording / reproducing apparatus, comprising: laser control means for performing control so as to change by a correction value corresponding to a later new linear velocity. The laser control means,
First storage means for storing a linear velocity correction value preset to correspond to a new linear velocity after the linear velocity has been changed;
Second storage means for storing a temperature compensation coefficient preset to correspond to the detected temperature near the laser diode;
4. The optical disk recording apparatus according to claim 3, further comprising a calculating unit that calculates the correction value from the linear velocity correction extracted from the first storage unit and the temperature compensation coefficient extracted from the second storage unit. Playback device.

Images