KR100636354B1 - Controlling Method of Recording Power in Optical Disc Recording Device and Controlling Device Used thereto - Google Patents

Abstract

The present invention includes the steps of obtaining a residual error signal from a focus error and / or tracking error; Detecting an absolute value from the residual error signal; And varying the magnitude of the laser power from the compensated signal (s) by multiplying the absolute value by the predetermined gain in accordance with the obtained absolute value. .

Recording power, servo control

Description

Controlling method for controlling recording power in an optical disc recording apparatus and a control device used therein {Controlling Method of Recording Power in Optical Disc Recording Device and Controlling Device Used used}

1 is an overall configuration diagram of an optical disk recording apparatus;

2 (a) is a relation diagram of a laser beam and a focus error signal

Figure 2 (b) is a relationship between the laser beam and the tracking error

3 shows focus and tracking error signal waveforms during servo operation.

4 is a configuration diagram of a laser power controller according to the present invention;

<Code Description of Main Parts of Drawing>

1: disc 2: objective

3: laser diode 4: photodetector

5: servo error detector 6: servo controller

7: Driver 8: Actuator

9: laser power controller 11,14: bandpass filter

12, 15: absolute value detection block 13, 16: signal compensation circuit section

17: signal addition circuit section

The present invention relates to a recording power adjusting method in an optical disk recording apparatus and a control apparatus used therein. More particularly, in the recording apparatus of an optical disk, laser power cannot be completely compensated through servo control during recording. The present invention relates to a recording power adjusting method and a control device used therein, which can improve the recording quality very accurately by a simple method of measuring an error.

The change of the recording power for optimal recording during recording in the optical disc is made through various means. As such means, OPC and ROPC are typical, and the recording power is changed during recording by various methods for each company and each model.

(OPC: means of finding the optimal recording power after recording by changing the amount of laser power irradiated to the disc in a very small area at the start of disc recording,

ROPC: A method of obtaining optimal recording quality by varying the recording power little by little depending on the disk status during recording, based on the optimal recording power obtained through OPC.)

The present invention provides a method for varying the laser power during actual recording on a disc, on the basis of the recording power obtained through OPC, to obtain an optimal recording quality.

The recording process includes generating heat on the surface of the disc by laser power and forming a pit by the generated heat. In the recording process, the pickup head (P / U head) records along the continuous track, so that the state of the optimal recording (that is, the shape of the RF generated by the pit shape when reproduced) cannot be confirmed. Therefore, instead of confirming the state of the reproduction RF, various methods have been proposed and used to determine the current recording state by various indirect methods, and to maintain the optimum quality by varying the laser power according to the determined recording state.

The recording is performed by focus servo and tracking servo operations to focus the laser beam irradiated onto the disk surface when recording to the optical disk (see Fig. 1).

The laser beam emitted from the laser diode A 3 is focused on the disk 1 via the objective lens 2.

The irradiated beam heats the disk surface to form pits, which in turn are reflected off the disk surface and reflected on photo detector B. The photodetector converts the irradiated beam into an electrical signal, a focus error that detects the vertical distance between the disc and the laser beam, and a tracking servo that detects the horizontal distance between the disc's track and the beam, depending on the shape of the reflected beam on the photodetector. The error component is input to the servo error detector 5.

The servo error detector 5 performs an electrical operation from an electrical signal input from the photo detector, generates a focus error and a tracking error, and transmits the generated focus error to the servo controller 6. The servo controller 6 receives these two servo errors as inputs and controls the movement of the objective lens 2 in the horizontal (tracking direction) and vertical direction (focusing direction) from the servo error currently input through the internal calculation process. In order to output the electrical signals (FAO, TAO) to the drive (7).

The amplified FAO and TAO signals are transmitted to the actuator 8. The actuator 8 has two degrees of freedom, moves in the vertical direction according to the magnitude and the sign of the amplified signal of the input FAO, and moves the laser beam in the horizontal direction according to the magnitude // sign of the TAO amplified signal. Move it so that it can be accurately focused on the surface and irradiated exactly on the track to form the correct pit at the desired position.

That is, the magnitude of the focus servo or tracking servo error is an amount indicating how much the laser beam is being irradiated in the vertical direction and the horizontal direction from the position where the pit should be formed, respectively (FIGS. 2A and B). As a result, the servo loop is operated so that the beam is moved to an optimal position (that is, the position where the magnitude of the focus and tracking servo error is zero, the position of B) by operating the focus actuator or the tracking actuator.

However, during actual servo operation, the focus error and track error move the objective lens 1 to minimize the focus error and track error as the servo loop operates. Have an error

However, even when the servo loop is in operation, the focusing and tracking servos are not always guaranteed to operate at the optimum position. In other words, the focus and tracking servo loops are limited in the range of servo loops due to the dynamics of the pick-up actuators used and the limits of the voltages and currents used. It is often operated (this error is represented by the residual component of the focus error, track error) (see FIG. 3).

Especially in the case of focus servo, the laser beam maintains the optimal focusing state because the cross section of the beam spot irradiated to the disk is the smallest and the effective power irradiated to the disk is the highest. When the condition is released, the effective power irradiated onto the disk is reduced so that the shape of the pit formed by the laser power has an inappropriate shape different from the optimal condition.

In this case, by observing the magnitude of the focus servo error, it is possible to indirectly observe the magnitude of the effective power applied to the disk, and to maintain the optimal recording quality by adjusting the amount of light emitted from the pickup according to the magnitude of the focus servo error. Can be.

SUMMARY OF THE INVENTION The present invention has been made to overcome the limitations of the prior art, and its object is to compensate the laser power, which cannot be completely compensated through servo control during recording, with a simple method very accurately in an optical disc recording apparatus. It is to provide a method of adjusting the possible recording power.

Another object of the present invention is to provide a recording power control apparatus which can be used to adjust the recording power in the optical disk recording apparatus.

The present invention according to the first aspect to achieve the above object

Obtaining a residual error signal from a focus error or tracking error; Detecting an absolute value from the residual error signal; And varying the magnitude of the laser power from the compensated signal by multiplying the absolute value by the predetermined gain in accordance with the obtained absolute value.

According to the invention according to the first aspect, the residual error signal is preferably provided through a bandpass filter.

According to the invention according to the first aspect, the compensated signal provides a regulation method, characterized in that the current or voltage signal.

In addition, the present invention according to the second aspect comprises the steps of obtaining each residual error signal from the focus error and tracking error; Detecting an absolute value from each residual error signal; And varying the magnitude of the laser power by multiplying the absolute value by the predetermined gain according to the obtained absolute value and summing each compensated signal to adjust the magnitude of the laser power.

According to the invention according to the second aspect, the residual error signal is preferably provided through a bandpass filter.

According to the present invention according to the second aspect, the compensated signal is preferably provided with a current or voltage signal.

Also, the present invention provides a filter circuit section for detecting a residual error signal from a focus error or tracking error, an absolute value detection block for detecting an absolute value from a signal output from the filter circuit section, and a gain predetermined in accordance with the obtained absolute value. There is provided a recording power control apparatus in an optical disk recording apparatus including a signal compensation circuit for compensating an output signal.

According to the second aspect of the present invention, there is also provided a filter circuit unit for detecting a residual error signal from a focus error and a tracking error, an absolute value detection block for detecting an absolute value from a signal output from the filter circuit unit, and the obtained absolute value. A recording power control device in an optical disc recording apparatus comprising a signal compensation circuit portion for compensating an output signal by a predetermined gain, and a signal addition circuit portion for adding up each of the compensated signals.

Hereinafter, the content of the present invention in more detail as follows.

The present invention is characterized by detecting a servo error (focus, tracking error) during recording in order to maintain an optimal recording state and varying the recording power in accordance with the magnitude or state of the servo error.

The focus error and track error are input to the laser power controller 9, and the laser power controller 9 supplies the laser diode A to vary the magnitude of the laser power according to the input focus error and the magnitude // direction of the track error. Adjust the magnitude of applied voltage / current.

As a result, the laser diode A increases or decreases the amount of emitted light and irradiates the disk through the objective lens 2 to create an optimal pit shape, thereby maintaining an optimum recording quality.

4 is a configuration diagram of a laser power controller according to the present invention, the filter circuit unit 11 for detecting a residual error signal from a focus error or a tracking error, and an absolute value for detecting an absolute value from a signal output from the filter circuit unit. The detection block 12 includes a signal compensation circuit 13 for compensating the output signal by a gain predetermined in accordance with the obtained absolute value.

The focus error signal passes through a filter circuit portion (e.g., a bandpass filter) to detect the focus error remaining as a residual error in the focus servo loop, and the detected signal passes through the absolute value detection block 12. Positions 1 and 3 of FIG. 2 detect the focus errors C and A, and since the intensity of the laser beam irradiated onto the disk surface is weaker than the optimum point 2, the positions 1 and 3 are both absolute value detection blocks to increase the laser power. 12). Thereafter, the signal compensation circuit unit 13 may compensate the output signal by multiplying an appropriate compensation gain value according to the obtained absolute value, and input the compensated signal to the laser diode 3 to adjust the amount of light emitted.

The above configuration can be equally applied to the case of using the residual error from the tracking error, and it is more preferable to implement the laser power controller as shown in FIG. 4 together with the residual error from the focus error.

Such circuits include filter circuit sections 11 and 14 for detecting residual error signals from focus errors and tracking errors, absolute value detection blocks 12 and 15 for detecting absolute values from signals output from the filter circuit section, and Signal compensating circuit parts 13 and 16 for compensating the output signal by a predetermined gain according to the obtained absolute value, and a signal adding circuit part 17 for adding each of the compensated signals.

The focus error FE and the track error signal TE pass through the filter circuits 11 and 14, for example, band pass filters, respectively, and the focus error and the tracking error remain as residual errors in the focus servo loop and the tracking error servo loop. Errors are detected respectively, and each detected signal passes through absolute value detection blocks 12 and 15.

Then, the signal compensation circuit unit 13, 16 compensates the output signal by multiplying an appropriate compensation gain value according to each of the obtained absolute values, and adds the compensated signal in the signal addition circuit unit 17. The signal summed up through the above process is input to the laser diode 3, thereby adjusting the amount of emitted light.

When the gain of any one of the signal compensation circuit sections 13 and 16 is set to zero in the above apparatus, it is also possible to adjust the light emission amount of the laser diode using only one component of the focus error or the tracking error.

According to the present invention, in the recording apparatus of the optical disk, it is possible to compensate the laser power, which cannot be completely compensated through servo control during recording, very accurately by a simple method of measuring the residual error, thereby greatly improving the recording quality. have.

As described above, although described with reference to a preferred embodiment of the present invention, those skilled in the art will be variously modified and modified within the scope of the present invention without departing from the spirit and scope of the present invention described in the claims below. It will be appreciated that it can be changed.

Claims (8)

Obtaining a residual error signal from a focus error or tracking error; Detecting an absolute value from the residual error signal; And varying the magnitude of the laser power from the compensated signal by multiplying the absolute value by a predetermined gain in accordance with the obtained absolute value. The method of claim 1, wherein the residual error signal is obtained through a bandpass filter. The method of claim 1 wherein the compensated signal is a current or voltage signal. Obtaining respective residual error signals from the focus error and tracking error; Detecting an absolute value from each residual error signal; And varying the magnitude of laser power by multiplying a predetermined gain by the absolute value according to the obtained absolute value and summing each compensated signal to adjust the magnitude of the laser power. 5. The method of claim 4, wherein the residual error signal is obtained through a bandpass filter. 5. The method of claim 4, wherein the compensated signal is a current or voltage signal. A filter circuit section for detecting a residual error signal from a focus error or tracking error, an absolute value detecting block for detecting an absolute value from a signal output from the filter circuit section, and an output signal obtained by a gain predetermined according to the obtained absolute value Recording power control device in an optical disc recording device including a compensating signal compensation circuit A filter circuit section for detecting a residual error signal from a focus error and a tracking error, an absolute value detecting block for detecting an absolute value from a signal output from the filter circuit section, and an output signal obtained by a gain predetermined according to the obtained absolute value A recording power control apparatus in an optical disc recording apparatus including a signal compensating circuit for compensating and a signal adding circuit for adding each of the compensated signals

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