KR20040068670A - Method for controling writing power in an optical-disc drive system and apparatus thereof - Google Patents

Abstract

PURPOSE: A method for controlling the recording power of an optical disk drive system is provided to make a reflected light peak level have more linear characteristics according to a change of a recording power, and to exactly detect the peak level in an analog circuit block, thereby adaptively controlling the recording power. CONSTITUTION: When a recording mode is set, a controller starts an OPC(Optimum Power Control) process(S21). The controller sequentially detects recording RF signals(S24), and sequentially detects sampled/held output signals(S27). The controller calculates a normalized recording RF signal(S30), and selects one of detected peak values to determine a relative recording power as an optimum recording power(S33). The controller sets the calculated recording RF signal to a reference value(S36), and starts a running OPC process(S39). The controller detects a peak value and a power value as recording substantial data in a substantial data area of an optical disk(S42), and calculates a normalized recording signal by using the peak value and the power value(S45). The controller obtains a difference value between a reference peak value and a substantial peak value(S48). If the two values are not identical, the controller controls the recording power(S51). The controller decides whether a predetermined data recording is completed, and records next data or completes the system according to decided results(S54).

Description

TECHNICAL-DISC DRIVE SYSTEM AND APPARATUS THEREOF TECHNICAL-DISC DRIVE SYSTEM AND APPARATUS THEREOF

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc drive system, and more particularly, to a method and apparatus for controlling recording power to obtain the best recording characteristics even when a recording environment is changed by controlling power for driving a laser diode (LD) when performing a recording mode. .

The optical disc drive system that is currently proposed has a corresponding optical disc through a recording power calibration area (PCA) on the optical disc when performing a recording mode for a write once type optical disc such as a CD-R or a DVD-R. To control the laser power (or recording power) level required to record the data. This task is called Optimal Power Control (OPC).

However, even if the optimum recording power has been obtained by OPC, good recording characteristics cannot be obtained if the recording environment changes during the actual recording. For example, beam spots may occur due to fluctuations in power sensitivity for each position on the optical disc, or because the wavelength of the LD is shifted to high temperatures, or because of disc skew, disc thickness and focus defocus. ), The actual recording is performed after a long time after performing the OPC, or the disc and / or optical conditions are changed, so that the optimal recording power determined by the above-described OPC is changed and recorded. The beta (beta or asymmetry) of the signal is changed so that good recording characteristics cannot be obtained.

In order to solve this problem, in the past, a running OPC that controls the recording power of the LD has been proposed so that an optimum recording characteristic can be obtained even if the recording environment changes during recording of actual data. That is, in the conventionally proposed running OPC, as shown in FIG. 1, when a recording pulse for the recording power is generated, the recording pulse for the recording power reflected from the optical disk starts to form a pit on the optical disk. The reflectance on the data recording surface of the optical disc is reduced. Accordingly, as shown in FIG. 1, even if the peak level of the recording pulses incident on the optical disk by the recording power gradually increases from one level to five levels, the recording pulses for the reflected recording power are shown in FIG. 2A in the case of CD-R. As shown in the figure, the level increases from 1 level to 2 levels, and pits are formed on the recording surface, and the reflectance decreases. At levels 3 through 5, the recording power level is drastically reduced to maintain a constant level. At this time, the peak level increases linearly with the power value. In addition, in the case of the DVD-R, the recording pulse for the reflected recording power has a form of reflected light relatively linear with respect to the peak level, as shown in FIG. 2B.

At this time, the sampling time point for the recording pulse of the recording power reflected normally becomes the point where the level of the recording pulse of the recording power is kept constant as shown in Fig. 2A.

The conventional running OPC method on the optical disk having the above-mentioned reflected light characteristics is obtained by performing an operation by measuring the value of the base level (B-level) using the reflected light characteristics as shown in FIG. By comparing the reference value, the laser beam power is adjusted in real time to approximate the reference value.

That is, when the running OPC is performed using the base level (B-level), as shown in the case of CD-R of FIG. 2A, the base level is lower when the power value incident on the recording surface is large at the time when the mark is formed. On the contrary, there is a nonlinearity where the base level becomes larger when the incident power value is small. Therefore, using this nonlinear characteristic, the sample and hold of the photodiode monitored for the WRF_B-level, which is a sampled and held RF signal of the B-level of the reflected light, as shown in Equation 1 below. The output power of the laser diode is controlled by obtaining the normalized recording RF signal with respect to the recording power, by mon_power.

Equation 1

WRF_B-level_Norm = WRF_B-level / Mon_Power

As such, an important point in performing the conventional running OPC is how accurately the peak level (Peak_level) and the base level (B_level) can be measured.

This is because, in most cases, if the sampling information of the sample and hold position information for obtaining peak and base level values is being sampled at the same position based on a constant reference clock pulse, the reflected light caused by external influence during recording If the positions of the peak and base levels change, this value will not be accurately measured. That is, the speed at which the marks are formed varies depending on the intrinsic material characteristics of the optical disc, so that the peak timing of the reflected light is changed, or as shown in FIG. Unlike the case of the CD-R, the reflected light forms a swing, and thus the value changes very sensitively depending on the sample position from which the value is obtained.

That is, in the case of the running OPC, the recording power value should be corrected while measuring the reflected light at the same time as the recording. Therefore, the amount of calculation should not be large, and if the accurate reflected light information cannot be obtained, recording characteristics may be rather impaired.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object thereof is to provide a recording power control method and apparatus capable of accurately detecting a peak level irrespective of a material characteristic of an optical disc or a change in a recording environment.

Another object of the present invention is to provide a recording power control method and apparatus capable of performing an accurate running OPC by detecting a peak level in consideration of the difficulty in detecting an existing base level in the case of a multi-pulse type DVD-R.

1 is a diagram showing incident recording pulses when recording data on a general optical disc.

2 shows recording pulses reflected in the case of a typical CD-R or DVD-R;

3 is a diagram showing the configuration of a recording power control apparatus of the optical disk drive system according to one preferred embodiment of the present invention.

4 shows recording pulses incident on an optical disk according to the present invention;

FIG. 5 is a diagram illustrating detecting a peak level according to operating period information provided by the encoder of FIG. 3. FIG.

6 is a flow chart for explaining a method of controlling the detonation power in the optical disk drive system according to an embodiment of the present invention.

7 shows a normalized graph of a recording RF signal of reflected light with respect to recording power in accordance with a preferred embodiment of the present invention.

<Name of the code for the main part of the drawing>

1: control unit 2: APC

3: LD driver 4: laser diode

5: beam splitter 6: objective lens

7: optical disc 8: photo diode

9: monitor photodiode 10: sampling and hold

11: I-V converter 12: RF amplifier

13: analog circuit block 14: encoder

According to a preferred embodiment of the present invention for achieving the above object, the recording power control method of the optical disk drive system, a) recording the test pattern using a plurality of recording power in the test area of the optical disk, the plurality of recording Setting a reference signal by detecting a normalized first recording signal having a linear characteristic with respect to recording power by using a peak level of reflected light reflected from the test area in response to power; b) while recording data in a data area of the optical disc, detecting a normalized second recording signal having a linear characteristic with respect to recording power by using a peak level of reflected light reflected from the data area; And c) comparing the first recording signal set as the reference signal with the second recording signal and adjusting the recording power of the light source according to the result.

The normalized first recording signal and the normalized second recording signal are calculated by calculating as follows.

WRF_Peak_Norm = WRF_Peak / Mon_Power

However, WRF_Peak_Norm is the first recording signal or the second recording signal,

WRF_Peak is a peak detected and held signal for the reflected light reflected from the optical disk,

Mon_Power is a sampled and held signal of a signal monitoring a beam radiated to the optical disc.

The peak level is detected from the 3.5T to 4T range after the reflected light.

In step a), the optimal recording power is determined using the reflected light corresponding to the plurality of recording powers, and the normalized first recording signal corresponding to the optimal recording power is set as the reference signal.

In step c), when the normalized first recording signal and the normalized second recording signal do not coincide, the recording power is adjusted according to the difference value.

According to another preferred embodiment of the present invention, the recording power control apparatus of the optical disc drive system includes: a peak detection and hold for peak detection and holding of reflected light reflected from the optical disc; Sampling and holding for sampling and holding a signal monitoring the amount of beams radiated to the optical disk; And in the recording mode for the optical disc, calculate a normalized recording signal having a linear characteristic with respect to the recording power by using signals output from the peak detection and hold and the sampling and hold, respectively, and calculate the calculated normalized recording. And a control unit for comparing the signal with the normalized reference recording signal obtained in the OPC process and controlling the recording power of the light source according to the result.

The encoder further includes an encoder for providing operation interval information for detecting a recording signal for a peak level among the signals output from the peak detection and hold.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

3 shows the configuration of a recording power control apparatus of the optical disk drive system according to an embodiment of the present invention. Referring to FIG. 3, the recording power control apparatus includes a control unit 1, an automatic power control (hereinafter abbreviated as APC) 2, a laser diode (LD) driver 3, and a laser diode (LD) 4 ), Beam splitter (5), objective lens (6), optical disk (7), photodiode (8), monitor photodiode (9), sampling and hold (Sampling & Hold) (10) ), An IV converter 11, an RF amplifier 12, an analog circuit block 13, and an encoder 14.

When performing the recording mode for the optical disc, the control unit 1 normalizes the linear power with respect to the recording power by using the peak level of the reflected light reflected from the PCA area of the optical disc 7 and reflected therefrom. Calculates the recorded RF signal (hereinafter referred to as WRF_Peak_Norm) and sets the reference value of the running OPC, and writes to the actual data area of the optical disc when the running OPC is performed, and linearly with respect to the recording power by using the peak level of reflected light reflected therefrom. A normalized recording RF signal having a characteristic is calculated and the recording power is adjusted according to the difference value by comparing this value with the reference value.

The normalized write RF signal WRF_Peak_Norm is calculated as shown in Equation 2 below.

Equation 2

WRF_Peak_Norm = (WRF_Peak) * (Mon_Power)

Here, the WRF_Peak value is a value obtained from the peak level of the reflected light reflected from the optical disc 7, and the Mon_Power value is a value obtained from light incident on the optical disc 7.

The controller 1 outputs a test write pulse to the LD driver 3 through the APC 2 for each power section in the recording mode (ie, when performing OPC). The LD driver 3 converts this write pulse into write power and controls it to be irradiated from the laser diode 4 in accordance with the write power.

In addition, the controller 1 controls the optical disk 7 to be irradiated with the optimal recording power determined when the OPC is performed when the running OPC is performed.

The APC 2 adjusts the reference value provided from the control unit 1 and the difference value between the reference value and the actual recording RF signal by the Mon_Power value provided at the sampling and holding to provide a constant recording power to the LD driver 3. do.

The LD driver 3 drives the laser diode 4 as a light source in accordance with a power control signal provided from the APC 2 to radiate a beam to the optical disk 7 side.

The beam splitter 5 separates the beam radiated from the laser diode 4 so as to be radiated to the objective lens 6 and the monitor photodiode 9, respectively, and the amount of light reflected through the objective lens 6 is photodiode. (8) perform the operation of separating the beam so that it can be provided.

The objective lens causes the beam radiated through the beam splitter 5 to be focused on the optical disc 7, and provides the beam splitter 5 with the amount of light reflected from the optical disc 7.

The photodiode 8 is driven according to the amount of light reflected from the optical disk 7 through the beam splitter 5 and the objective lens 6 to output a current signal.

The I-V converter 11 converts the current signal output from the photodiode 8 into a voltage signal and outputs it.

The RF amplifier 12 amplifies the voltage signal output from the I-V converter 11 to a predetermined value and outputs it to the analog circuit block 13.

The analog circuit block 13 detects the peak level of the voltage signal amplified from the RF amplifier 12 by using the operating period 3.5T to 4T provided from the encoder 14 and controls the control unit 1. Will output

The analog circuit block 13 is composed of a peak detector and hold. Accordingly, the analog circuit block 13 detects a peak level present within an operating period provided from the encoder 14 based on the rising edge of a specific nT pattern of an internal EFM (Eight to Fourteen Modulation) write pulse. do.

The encoder 14 provides an operation time point to the LD driver 3 and provides operation period information 3.5T to 4T in which the analog circuit block 13 operates based on the recording pattern.

As shown in FIG. 4, unlike CD-R, DVD-R has a recording pattern in the form of a multi-pulse, and the length of the Ttop pulse for determining the peak level of the reflected light has a width of at least 1T and at most 1.7T. Have In this case, it can be seen that the falling edge of the Ttop pulse does not exceed 3T based on the rising edge of the internal EFM recording pattern. Therefore, as shown in FIG. 5, the width of the section for detecting the peak level in the analog circuit block 13 may be set to about 3.5T to 4T in consideration of the delay of the reflected light. Accordingly, the encoder 14 outputs 3.5T to 4T operation interval information to the analog circuit block 13 so that the peak level is increased after 3.5T to 4T based on an internal EFM recording pattern in the analog circuit block 13. To be detected.

On the other hand, the monitor photodiode 9 is driven according to the amount of beam radiated from the laser diode 4 through the beam splitter 5 and outputs the output signal Mon_Power of the monitored photodiode.

Sampling and hold sample and hold Mon_Power transmitted from the monitor photodiode 9 at a predetermined time. Mon_Power obtained from sampling and holding is output to the APC 2 and the control unit 1, respectively.

6 is a flowchart illustrating a method of controlling the detonation power in the optical disk drive system according to an exemplary embodiment of the present invention. 3 and 6, when the recording mode is set, the controller 1 starts performing the OPC process (S 21).

Accordingly, the controller 1 controls the plurality of recording powers set by the laser diode 4 through the APC 2 and the LD driver 3 so that the test pattern is recorded in the PCA area existing on the optical disc 7. At the same time, the write RF signal WRF_Peak is sequentially detected through the photodiode 8, the IV converter 11, the RF amplifier 12, and the analog circuit block 13 in feet (S 24). At this time, the WRF_Peak value is detected for the peak level among the voltage signals inputted by the peak detection and hold of the analog circuit block 13.

In addition, the controller 1 sequentially detects an output signal Mon_Power sampled and held through the monitor photodiode 9, sampling and holding by reflecting a part of the recording power incident to the optical disc 7 (S 27). ).

The controller 1 calculates the normalized write RF signal WRF_Peak_Norm by applying the WRF_Peak value and the Mon_Power value detected in S 23 and S 25, respectively, to Equation 2 (S 30).

The normalized write RF signal is thus calculated for a plurality of established long powers.

The controller 1 selects one of the WRF_Peak values detected for each power section and determines a corresponding recording power as an optimum recording power (S 33). In this case, the conventional method of recording the test pattern in the existing PCA area, detecting the reproduction RF signal for each recording power, and using the sum and difference of the top and the bottom is used.

In this case, the normalized write RF signal WRF_Peak_Norm calculated by the WRF_Peak used to determine the optimal write power is set as a reference value (S 36).

As such, when the reference WRF_Peak_Norm is set through the OPC process, the execution of the running OPC process is started (S 39).

When the running OPC process is performed, the controller 1 detects the WRF_Peak value and the Mon_Power value for a specific nT while recording real data in the real data area on the optical disc 7 (S 42). This is the same process as S 24 and S 25. However, S 24 and S 25 use the test pattern recorded in the PCA area of the optical disc 7, whereas S 42 uses the data area in which the actual data of the optical disc 7 is recorded.

At this time, in a specific nT, there are write pulses having different widths in one power section. For example, any recording pulse between 3T and 14T can be used for DVD-R.

Therefore, the detection of both the WRF_Peak and Mon_Power values for all of the different recording pulses in the power section is limited in time and physically. Therefore, WRF_Peak is only available for recording pulses having a specific width nT for each power section. By detecting the value and the Mon_Power value, the recording power can be controlled more efficiently.

Next, the normalized recording signal WRF_Peak_Norm is calculated using the detected WRF_Peak value and the Mon_Power value as in S30 (S45). Here, the calculated normalized recording signal WRF_Peak_Norm means the actual normalized value detected while recording on the actual optical disc 7.

As shown in FIG. 7, it can be seen that the value obtained by dividing the WRF_Peak value by the Mon_Power value is non-linear, whereas the value obtained by multiplying the WRF_Peak value by the Mon_Power value appears linearly.

As described above, the WRF_Peak value for the recording power is linear, so that the recording power can be more accurately controlled.

When the actual WRF_Peak_Norm value is calculated, the difference is obtained by comparing the reference WRF_Peak_Norm value with the actual WRF_Peak_Norm value (S48).

That is, when the reference WRF_Peak_Norm value and the actual WRF_Peak_Norm value match, the difference does not exist, and thus the optimum recording power determined in the OPC process is used as it is.

On the other hand, if the reference WRF_Peak_Norm value does not match the actual WRF_Peak_Norm value, the difference exists. Therefore, the difference value is calculated and the recording power is adjusted according to the calculated value (S 51).

For example, if the reference WRF_Peak_Norm value is larger than the actual WRF_Peak_Norm value, the actual WRF_Peak_Norm value becomes relatively smaller than the existing WRF_Peak_Norm value, so that the recording power is increased so that the actual WRF_Peak_Norm value matches the reference WRF_Peak_Norm value. At this time, the recording power is preferably the optimum recording power determined in the OPC process.

On the contrary, when the reference WRF_Peak_Norm value is smaller than the actual WRF_Peak_Norm value, since the actual WRF_Peak_Norm value becomes a relatively larger value than the existing WRF_Peak_Norm value, the recording power is reduced so that the actual WRF_Peak_Norm value matches the reference WRF_Peak_Norm value.

At this time, the controller 1 judges whether or not the predetermined data recording is completed in the data area on the optical disc 7 and, according to the result, records the next data or terminates the system (S 54).

Accordingly, by making the WRF_Peak value for the recording power more linear as described above, the recording power can be controlled more accurately in real time when the running OPC is performed.

As described above, according to the method and apparatus for controlling the recording power of the optical disk drive system according to the present invention, the peak level of the reflected light from the optical disk surface according to the change of the recording power has a more linear characteristic, such that in the analog circuit block By detecting the peak level more accurately and applying it to running OPC performance, the recording power can be adaptively controlled to have better recording characteristics.

In addition, in the case of DVD_R in the form of pulse pulses, it is difficult to detect the base level (B-level) due to the reflected light, thereby detecting the peak level and controlling the recording power, thereby making it easier to control the recording power. have.

Claims (8)

A method of controlling the recording power of a light source for emitting a laser beam in order to record data on an optical disc in an optical disc drive system, a) recording a test pattern in a test area of the optical disc using a plurality of recording powers, and having a linear characteristic with respect to the recording power by using a peak level of reflected light reflected from the test area corresponding to the plurality of recording powers; Setting a reference signal by detecting the normalized first recording signal; b) while recording data in a data area of the optical disc, detecting a normalized second recording signal having a linear characteristic with respect to recording power by using a peak level of reflected light reflected from the data area; And c) comparing the first recording signal set as the reference signal with the second recording signal and adjusting the recording power of the light source according to the result; Recording power control method of an optical disk drive system comprising a. The recording power control method of claim 1, wherein the normalized first recording signal and the normalized second recording signal are calculated by calculating as follows. WRF_Peak_Norm = WRF_Peak / Mon_Power However, WRF_Peak_Norm is the first recording signal or the second recording signal, WRF_Peak is a peak detected and held signal for the reflected light reflected from the optical disk, Mon_Power is a sampled and held signal of a signal monitoring a beam radiated to the optical disc. The recording power control method of claim 1, wherein the peak level is detected from a range after a predetermined operating period of the reflected light. 4. The method of claim 3, wherein the operation period is in the range of 3.5T to 4T. The method of claim 1, wherein in step a), The optimal recording power is determined using the reflected light corresponding to the plurality of recording powers, and the normalized first recording signal corresponding to the optimal recording power is set as a reference signal. The method of claim 1, wherein step c) And when the normalized first recording signal and the normalized second recording signal do not coincide, adjusting the recording power according to the difference value. An apparatus for controlling the recording power of a light source that emits a laser beam to record data on an optical disc in an optical disc drive system, A peak detection and hold for peak detection and holding of reflected light reflected from the optical disk; Sampling and holding for sampling and holding a signal monitoring the amount of beams radiated to the optical disk; And In the recording mode for the optical disc, a normalized recording signal having a linear characteristic with respect to the recording power is calculated by using signals output from the peak detection and hold and the sampling and hold, respectively, and the calculated normalized recording signal. Is compared with the normalized reference recording signal obtained in the OPC process and controls the recording power of the light source according to the result. Recording power control device of an optical disk drive system comprising a. The encoder according to claim 7, wherein the encoder provides operation section information for detecting a recording signal for a peak level among signals output from the peak detection and hold. Recording power control device of the optical disk drive system further comprising.