JP2003338037A - Optical disk recording device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide an optical disc recording apparatus which eliminates an error in optimum recording power and does not deteriorate recording quality in Zone CLV recording. SOLUTION: A recording area of an optical disc can be divided into a plurality of zones, and a recording speed can be switched for each zone. A laser power calculating means for calculating differential efficiency from a relationship with a drive signal; and a switching laser power predicting means for predicting an optimum recording power immediately after switching using differential efficiency when switching zones; Is characterized in that recording is performed with the optimum recording power predicted by the switching laser power prediction means 10a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc recording apparatus capable of performing recording with an optimum recording power even when a recording zone is switched when performing Zone CLV recording, and recording quality is not deteriorated.

[0002]

2. Description of the Related Art The structure of an optical disk recording apparatus will be described with reference to FIG. FIG. 6 is a laser power control block diagram of a conventional optical disk recording apparatus. In FIG. 6, 1 is a photodiode for a laser power sensor, 2 is a laser diode (LD), 3 is a VI converting means, 4 is a DA converting means, 5 is an amplifying means, 6 is a comparing means, 7 is a laser power detecting means. , 8 is a laser power driving means, 9 is a laser power setting means, 10 is a laser power calculating means, and 11 is a central processing unit (CPU).

The automatic laser power control configured as described above will be described. The laser power sensor photo diode 1 receives a part of the light emitted by the laser diode 2, photoelectrically converts the received light amount into an electrical analog signal, and the converted signal is input to the amplification means 5. It The signal amplified by the amplifying means 5 is compared with a predetermined set value set by the laser power setting means 9, and is input to the laser power detecting means 7 in the CPU 11 as a differential signal. The laser power drive means 8 in the CPU 11 outputs a laser drive signal to the DA conversion means 4 based on the result detected by the laser power detection means 7 in the CPU 11.

The laser drive signal converted into an analog signal by the DA conversion means 4 is converted into a current value for actually causing the laser to emit light by the VI conversion means 3. For example, the result of the signal of the amplifying means 5 in the comparing means 6 being lower than the value set by the laser power setting means 9 is the CPU.
When input to the laser power detecting means 7 in 11, the laser power driving means 8 sets a value higher than the current set value. With the above configuration, for the desired laser power,
Automatic control that keeps emitting light with constant laser power is performed.

Next, an OPC (Optimum Power Control) process for determining the optimum recording laser power for each recording disk will be described. In an optical disc recording apparatus for recording / reproducing information on / from a CD-R disc, trial writing is performed using a trial writing area PCA (Power Calibration Area) prepared in advance on the disc to determine the laser power at the time of recording. It is common practice to carry out recording on the data area of the disc under the obtained recording condition by using the optimum recording laser power obtained from the result. A series of methods for obtaining the optimum recording laser power using this test writing area is called OPC.

OPC is executed in the PCA (area A shown in FIG. 3) located on the inner circumference side of the data area of the disc. FIG. 3 is a side view of the optical disc showing an area for trial writing on the optical disc. 2 to 5 including FIG.
FIG. 4 is a diagram for explaining the first embodiment of the present invention, but since it has the same content in the conventional technique, it will be described in common below. PCA is a test area (B shown in FIG. 3).
Area) and Count Area (area C shown in FIG. 3). The Test Area is an area for performing trial writing by changing the recording power in multiple stages, and the Count Area is
This is an area for recording how many times trial writing has been executed.

FIG. 4 is a diagram showing a region of an optical disk used for one OPC and changes in laser power. The area of Test Area that is allowed to be used by executing OPC once is 15
This is a frame, and these 15 frames are used for trial writing of random data.

In the OPC process, roughly two processes are performed. The first process is ALPC (Au
This is called tomatic Laser Power Control) processing, and is used to calculate the differential efficiency of the laser diode.

In this process, first, the laser power setting means 9 in the CPU 11 sets the reference power determined in advance for each disk. The laser power driving means 8 in the CPU 11 has a signal detected by the laser power sensor photodiode 1 and amplified by the amplifying means 5 by the comparing means 6, and the laser power setting means 9 in the CPU 11.
The signal to the DA converting means 4, that is, the value of the laser power driving means 8 is increased or decreased so that the difference from the setting output from the laser power detecting means 7 in the CPU 11 becomes zero.

When the value set by the DA converting means 4 is 0, the recording power becomes 0 mW and only the reproducing power is obtained. Therefore, from the value obtained when the reference power is emitted and the set power, A linear expression of the laser power and the setting value of the DA conversion means is obtained. The slope of this linear equation is called the differential efficiency of the laser diode, and this process is called the ALPC process during the OPC operation.

By this processing, an accurate relationship between the laser power driving means in the CPU 11 and the laser emission power can be obtained. The ALPC process uses 5 frames after the 15 frames. In the second OPC processing, the laser power is set to 10 steps above and below the reference power based on the reference power in 10 frames before the 15 frames, and trial writing is executed with each laser power as 1 frame as 1 step. To do. From the result of the trial writing, the optimum recording power that the optical disk device has for each disk is obtained in advance.

Next, the optical recording disk is divided into several zones, and the zone CLV (C
The onstant linear velocity recording will be described with reference to FIG. FIG. 5 is a diagram showing the relationship between zones and recording areas of the disc during Zone CLV recording. In the Zone CLV recording method, the data area of the optical recording disk is divided into several zones in advance, and the recording speed of the CLV recording with a constant linear velocity is increased from the innermost zone of the disk, Zone 1.

Since the recording speed is different for each zone, the amount of heat applied to the optical recording disk per unit time is naturally different at the same recording power. Therefore, in the Zone CLV recording method, the optimum recording power obtained by OPC is used for zone 1
In the zone 2 in which the recording speed is increased, the recording is performed with the recording power obtained by multiplying the optimum recording power obtained by the OPC by a predetermined correction amount. In the following zone 3 as well, recording is similarly performed with the recording power multiplied by the correction amount previously determined for zone 3. Like this Zone C
In the LV recording system, each zone has an optimum recording power. The recording laser power during recording in each zone is automatically controlled as described above.

[0014]

The conventional Zone C will be described below.
The LV recording method will be described with reference to FIG. Figure 2
It is a figure which shows the relationship between the laser power at the time of Zone CLV recording, and the set value of the DA conversion means for making a laser emit, and when dividing a disk into two zones and performing Zone CLV recording, of a DA conversion means. It shows the relationship with the set value.

Zone 1 is for 8x CLV recording, zone 2 is for 12x CLV recording, and Pw1 is 8x CL.
The optimum recording power for V recording (zone 1), α1 is Pw1
Is an IP2 value for causing the light emission. Pw2 represents the optimum recording power during 12 × speed CLV recording (zone 2), β
1 is an IP2 value for causing Pw2 to emit light.

Here, the IP2 value means a DA converter setting value. The relationship between the IP2 value for causing the laser to emit light and the laser power for actually emitting light is as follows.
If the reproducing power during writing is Pr, then Pw = ηIP2
It can be expressed by a linear function of + Pr (Equation 1). Note that Pr is set to 1 mW.

The differential efficiency of the laser is the slope η of the above-mentioned linear function representing the relationship between the set value of the DA conversion means and the write power. The value of the differential efficiency η of the laser diode is characterized in that it decreases due to self-heating when the laser diode emits light with high power.

The CD-R of the write-once type recording medium is a Zone CLV.
When recording, OPC is executed in the innermost PCA area of the recording disc, and the value is used to record zone 1. Zone 2 only multiplies the optimum recording power obtained by OPC by a predetermined correction coefficient. That is, in FIG. 2, since the optimum recording power of zone 2 is designed to be 1.2 times the optimum recording power of zone 1,
× 1.2 = 24 mW.

However, in actuality, during recording in the zone 1, the self-heating of the laser diode causes the differential efficiency to decrease. When the optical disk recording apparatus records a recording disk in Zone CLV, recording is performed from zone 1, recording is completed in the entire area of zone 1, and when zone 2 is reached, with η obtained by ALPC processing of OPC ( If the setting value of the DA converting means is calculated based on the equation (1), it must be set as β1 value = 367, but in reality, as shown in the equation (2), η decreases and η. '
Has become.

Pw = η'IP2 + Pr (Equation 2) Follow

Therefore, when the β1 value is set when recording the zone 2, it becomes 23 mW according to (Equation 2). As a result, the corrected optimum recording power of zone 2 is 2
Since it is 4 mW, an error of 1 mW will occur.
Furthermore, the amount of change in the differential efficiency η varies depending on various factors such as the environment in which the optical recording drive is used (ambient temperature) and the amount of recording in zone 1 during additional recording, so grasp the amount of change in advance. It is impossible to determine the correction coefficient of the recording power between the zones.

However, since the laser power is automatically controlled as described above, it is possible to gradually approach the optimum recording power during recording. However, as described above, when performing recording in zone 2, recording is not performed at the optimum recording power from the moment the recording is started until the optimum recording power is changed by automatic control of the laser power. However, there is a problem that there is an area where the recording quality is deteriorated.

The present invention has been made to solve the above problems, and when performing Zone CLV recording, the power is automatically controlled from the moment the recording zone is switched, even if the differential efficiency of the light emitting portion changes. It is an object of the present invention to provide an optical disc recording apparatus which eliminates the error of the optimum recording power up to the above and does not deteriorate the recording quality.

[0024]

In order to achieve the above object, the optical disk recording apparatus of the present invention can divide the recording area of the optical disk into a plurality of zones and switch the recording speed for each zone. In the optical disc recording apparatus for automatically controlling the light emission power during recording to approach the optimum recording power, the power calculation means for calculating the differential efficiency, and the optimum recording power immediately after the switching are predicted at the time of switching. A power estimating means is provided, and recording is performed with the optimum recording power predicted by the switching power estimating means immediately after the zone switching.

As a result, when performing Zone CLV recording, even if the differential efficiency of the light emitting portion changes, the error in the optimum recording power from the moment the recording zone is switched to when the power is automatically controlled is eliminated, and the recording quality is improved. Does not make it worse.

[0026]

The invention according to claim 1 of the present invention can divide the recording area of the optical disc into a plurality of zones and switch the recording speed for each zone, and the emission power during recording in each zone can be changed. An optical disk recording device for performing automatic control for approaching an optimum recording power, comprising a power calculation means for calculating a differential efficiency from a relationship between a light emission power and a drive signal, and a zone immediately after switching using the differential efficiency when switching zones. Equipped with a switching power prediction means for predicting the optimum recording power, immediately after zone switching, recording is performed with the optimum recording power predicted by the switching power prediction means,
An optical disc recording device characterized by reducing an error between a light emission power and an optimum recording power until the optimum recording power is controlled by automatic control, wherein the light emission power is automatically controlled immediately after the recording speed is switched. Until this is done, it is possible to avoid the problem of deterioration of recording quality caused by recording with a power deviating from the optimum recording power.

According to a second aspect of the present invention, the power calculation means monitors the drive signal necessary for causing the light emitting section to emit light at a predetermined power, and calculates the differential efficiency from the monitored signal value. The optical disc recording apparatus according to claim 1, wherein the amount of change in the differential efficiency of the light emitting unit is known before the recording speed is switched, whereby the emission power is automatically controlled immediately after the recording speed is switched. Until then, the problem that the optimum recording power has an error can be avoided.

In the invention according to claim 3 of the present invention, the switching power predicting means, when switching the zone, uses the differential efficiency immediately before switching calculated by the power calculating means to determine the optimum recording power immediately after switching. 3. The optical disk recording apparatus according to claim 1 or 2, wherein the optimum recording power is recalculated from immediately after the recording speed is changed until the emission power is automatically controlled. It is possible to avoid the problem that an error occurs in the optimum recording power.

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a laser power control block diagram of an optical disk recording apparatus according to Embodiment 1 of the present invention. 2 to 5 will also be used in the description of the optical disc recording apparatus according to the first embodiment of the present invention.
In FIG. 1, 1 is a photodiode for a laser power sensor, 2 is a laser diode (the light emitting portion of the present invention), 3
Is V-I conversion means, 4 is DA conversion means, 5 is amplification means,
6 is a comparing means, 7 is a laser power detecting means, 8 is a laser power driving means, 9 is a laser power setting means, 10 is a laser power calculating means (power calculating means of the present invention), 10
Reference numeral a is a switching laser power prediction means (switching power prediction means of the present invention), and 11 is a CPU. A laser power correction method for Zone CLV recording in the embodiment of the present invention configured as described above will be described.

First, the automatic control of the laser power is shown in FIG.
Will be explained. The laser power sensor photo diode 1 receives a part of the light emitted by the laser diode 2, photoelectrically converts the amount of the received light into an electrical analog signal, and the converted signal is input to the amplification means 5. It
The signal amplified by the amplification means 5 is compared with the desired set value set by the laser power setting means 9, and is input to the laser power detection means 7 in the CPU 11 as a differential signal.

The laser power driving means 8 in the CPU 11 outputs a laser driving signal to the DA converting means 4 based on the result detected by the laser power detecting means 7 in the CPU 11. The laser drive signal converted into the analog signal by the DA converting means 4 is converted into the current value for actually causing the laser to emit light by the VI converting means 3. With the above configuration, automatic control is performed in which the laser power (light emission power of the present invention) is brought closer to the desired laser power (optimum recording power) and light emission is continued at a constant laser power.

Next, an OPC (Optimum Power Control) process for determining the optimum recording laser power for each recording disk will be described. The OPC is as described in the related art.

The OPC is executed in the area of the PCA (A shown in FIG. 3) located on the inner side of the data area of the disc, and the Test Area (B of FIG. 3) and the Count Area (C of FIG. 3).
It is composed of two areas. The Test Area is an area for performing trial writing by changing the recording power in multiple steps.
The unt Area is an area indicating how many times trial writing has been executed.

The area of the Test Area which is allowed to be used by executing the OPC once shown in FIG. 4 is 15 frames, and these 15 frames are used for trial writing of random data. In the OPC process, two processes are performed. The first process is ALP during OPC operation.
This is called C processing, and calculates the differential efficiency of the laser diode. In this process,
First, the laser power setting means 9 in the CPU 11 sets the reference power determined in advance for each disk.

Laser power driving means 8 in CPU 11
Is a signal detected by the laser power sensor photodiode 1 by the comparison means 6 and amplified by the amplification means 5,
The signal to the DA converting means 4, that is, the output value of the laser power driving means 8 is increased or decreased so that the difference from the setting output from the laser power setting means 9 in the CPU becomes 0 in the laser power detecting means in the CPU 11. Let

When the value set by the DA conversion means is 0,
Since the recording power is 0 mW, the relational expression of the laser power and the set value in the DA conversion means can be obtained from the value obtained when the reference power is emitted and the set power. This relational expression is a linear expression and is described by the above (Equation 1).
The slope η of this linear expression is the differential efficiency of the laser diode, and the process for obtaining this η is the ALPC process during the OPC operation. ALPC processing uses 5 frames after the 15 frames.

In the second processing of OPC, the laser power is set to 10 steps above and below the reference power based on the reference power in 10 frames before the 15 frames, and one frame is set as one step and each laser power is tested. It is to execute writing. From the result of the trial writing, it is possible to previously obtain the optimum recording power that the optical disk device has for each disk.

Zone CLV recording in which the optical recording disk is divided into several zones and the recording power is varied for each zone will be described with reference to FIG. In the Zone CLV recording method, the data area of the optical recording disc is divided into several zones in advance, and the linear velocity is kept constant in each zone from the innermost zone 1 of the disc to increase the recording speed of CLV recording.
Since the recording speed is different for each zone, the amount of heat applied to the optical recording disk per unit time is naturally different at the same recording power.

Therefore, in the Zone CLV recording system, OPC
The zone 1 is recorded with the optimum recording power obtained in step 2, and the zone 2 where the recording speed is increased records with the recording power obtained by multiplying the optimum recording power obtained by the OPC by a predetermined correction amount. In the following zone 3 as well, recording is similarly performed with the recording power multiplied by the correction amount previously determined for zone 3. Thus, in the Zone CLV recording system,
It has an optimum recording power for each zone. The recording laser power during recording in each zone is automatically controlled as described above.

By the way, when the laser diode continues to emit light with high power, the characteristic thereof is that the differential efficiency is lowered due to self-heating. That is, referring to FIG. 5, the self-heat generation amount of the laser diode is different between the case where the zone 2 is recorded after the entire surface of the zone 1 is recorded and the case where the zone 1 is already recorded and the zone 2 is recorded. , The differential efficiency is different.

In the first embodiment, the set value (IP2) given to the DA conversion means shown in FIG.
The output value from the laser power driving means 8 therein is fed back to the laser power calculating means 10.

Therefore, the calculation of the optimum recording power of each zone will be described with reference to FIG. In FIG. 2, the disk has three zones shown in FIG.
8 times speed CLV recording and zone 2 at 12 times speed CLV recording. First DA converter setting value (IP2) α for emitting the optimum recording power in zone 1
1 uses η obtained by ALPC processing of OPC,
Calculated by (Equation 1). Optimum recording power in zone 1 20mW
Α1 for emitting light is calculated as 304.

By the way, since the laser diode self-heats during recording in zone 1, the differential efficiency η decreases, and if the IP2 value α1 at the start of zone 1 recording is 304, it is 20.
Since mW cannot be emitted, the IP2 value rises due to automatic control, and immediately before the end, the IP2 value rises to α2. In FIG. 2, α2 is 317. If the optimum recording power for zone 2 is calculated using (Equation 1), the IP2 value is β1, which is 367 in FIG.

However, in practice, the differential efficiency η decreases and η '
Therefore, if β1 is 367, it is 2 according to (Equation 2).
It becomes 3 mW, which is below the optimum recording power for zone 2.
However, since the automatic control of the laser power naturally works, the optimum recording power of the zone 2 is reached with the passage of time, but it is optimum until the optimum recording power of the zone 2 is reached by the automatic control. The recording power deviated from the recording power is emitted.

Therefore, in the first embodiment, the zone 2
Before the start of the recording of
The P2 value α2, that is, 317 is monitored and fed back to the laser power calculation means 10 in the CPU 11.
Next, according to (Equation 2), when α2 is 317, the laser power is 20 mW, and the read power Pr is 1 mW.
Therefore, η'is calculated in advance. And zone 2
When the recording is started, the calculated laser power is used to calculate the η '(Equation 2) so that the switching laser power predicting means 10a emits the optimum recording power in the zone 2,
That is, the β2 value is calculated in advance. The β2 value calculated by the switching laser power prediction means 10a is 383.

In FIG. 2, as described above, the output of the laser power driving means (IP
2) is fed back to the laser power calculation means 10,
The change rate of the differential efficiency of the laser diode 2 is calculated, and immediately before the recording speed is switched, the switching laser power predicting means 10a calculates the IP2 value for outputting the optimum recording power of the next zone. It is possible to avoid an error in the optimum recording power from immediately after the change of the optimum recording power and the optimum recording power is switched to when the automatic control of the laser power is performed. Since the recalculation process of the differential efficiency η can be executed during the switching of the rotation speed of the disc from the 8 × speed to the 12 × speed, the processing time until the recording speed is switched and the recording is started is compared with the conventional one. And will not extend.

The contents of the present invention are not limited to the case where the zones for dividing the recording speed of the disc in the Zone CLV recording are two zones, and can be similarly applied when the zone (N) is shifted to the zone (N + 1). That is, the IP2 value immediately before the end of recording in zone (N) is fed back to the laser power calculating means 10 to calculate the differential efficiency η (N) at the end of recording in zone (N), thereby obtaining zone (N + 1). It is possible to calculate the IP2 value for emitting the optimum recording power at the start of recording, and avoid an error in the optimum recording power from the start of recording until the laser power is automatically controlled. It becomes possible.

[0049]

As described above, according to the optical disk recording apparatus of the present invention, the error of the optimum recording power immediately after the change of the recording speed and the change of the optimum recording power until the automatic control of the laser power is performed. Therefore, there is no area where the recording quality deteriorates, and stable recording quality can be obtained over the entire surface of the optical disc.

[Brief description of drawings]

FIG. 1 is a laser power control block diagram of an optical disk recording device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a laser power at the time of Zone CLV recording and a set value of a DA conversion unit for causing the laser to emit light.

FIG. 3 is a side view of an optical disc showing an area for trial writing on the optical disc.

FIG. 4 is a diagram showing a region of an optical disc used for one OPC and a laser power change.

FIG. 5 is a diagram showing a relationship between zones and recording areas of a disc at the time of Zone CLV recording.

FIG. 6 is a laser power control block diagram of a conventional optical disc recording apparatus.

[Explanation of symbols]

1 Photodiode for laser power sensor 2 Laser diode 3 VI conversion means 4 DA conversion means 5 Amplification means 6 comparison means 7 Laser power detection means 8 Laser power driving means 9 Laser power setting means 10 Laser power calculation means 10a Laser power predicting means during switching 11 Central Processing Unit (CPU)

Claims (3)

[Claims] 1. An optical disk recording apparatus capable of dividing a recording area of an optical disk into a plurality of zones and switching a recording speed for each zone, and performing automatic control for making a light emission power during recording close to an optimum recording power in each zone. The power calculation means for calculating the differential efficiency from the relationship between the emission power and the drive signal, and the switching power prediction means for predicting the optimum recording power immediately after the switching by using the differential efficiency at the time of zone switching. Just after the zone switching, recording was performed with the optimum recording power predicted by the switching power prediction means, and the error between the emission power and the optimum recording power until the optimum recording power was controlled by the automatic control was reduced. An optical disk recording device characterized by the above. 2. The power calculation means monitors a drive signal required for causing the light emitting section to emit light with a predetermined light emission power, and calculates a differential efficiency from the monitored signal value. Optical disc recording device. 3. The switching power predicting means calculates the optimum recording power immediately after switching by using the differential efficiency immediately before switching calculated by the power calculating means when switching zones. Item 1. The optical disk recording device according to Item 1 or 2.