KR100244773B1 - Method for controlling offset level of tracking error in optical disc player - Google Patents

Abstract

The present invention relates to an offset adjustment method of an optical disc player, wherein the amount of light reflected from the optical disc during the reproduction of the optical disc is detected by a divided optical diode, and the difference between the detected RF signal and the detected amount of light is generated. A method of adjusting an offset level of an optical disc player for measuring and removing an offset level which is an error between a point where a tracking error signal becomes zero and a point where actual tracking coincides using a tracking error signal generated by A first step of dividing and setting a plurality of sections and detecting a tracking error signal and an RF signal in each section; A second step of comparing a plurality of RF signals detected in the first step with a tracking error signal, respectively, and measuring an offset level corresponding to each of the sections; A third step of performing tracking servo based on the detected offset level after detecting the offset level corresponding to the current playback position from the offset level measured in response to the respective sections when the optical disc is reproduced; By providing an offset adjustment method of the optical disc player comprising a, there is an effect that can improve the reliability of the optical disc player system through accurate and quick offset adjustment.

Description

How to adjust the offset of the optical disc player

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc player, and more particularly, to an offset adjustment method of an optical disc player for measuring and eliminating offset levels present in a tracking error signal.

In general, an optical disc player capable of playing video includes a laser disk player (LDP), a video compact disk player (VCDP), and the like. Compression techniques are used to provide viewers with video and audio by playing back optical discs with video and audio data of several gigabytes (GB).

As described above, the optical disc player has a higher signal-to-noise ratio than conventional video / audio playback devices, so that signals can be reproduced with better image quality / sound quality, no noise due to irregular playback and modulation, and distortion is very low. Not only is there no ghost, but random access is possible, and there are various advantages such as providing various functions such as a music accompaniment function.

On the other hand, in order to accurately read the data recorded on such an optical disc, the optical pickup of the optical disc player must accurately follow the track of the pitch formed on the optical disc.

If the tracking control is not performed smoothly, it is difficult to accurately read the data recorded due to impact or disturbance during reproduction.

Therefore, even if the disk rotates eccentrically, the tracking control is performed so that the laser beam of the optical pickup is accurately followed along the tracks at a predetermined interval. The tracking control device is generally called a tracking servo, and the general operation process thereof is shown in FIG. Referring to the following.

1 is a block diagram illustrating a tracking servo device according to a related art, including a photodetector 100, a current-voltage converter 200, an error detector 300, a phase compensator 40, and a driver 50. )

First, the photo detector 100 is composed of two photo diodes D1 and D2 divided into two, and detects the light reflected from the optical disk through the respective photo diodes D1 and D2, and the detected Generates a current corresponding to light.

The two sets of current-voltage converters 200 are composed of two sets of OP amplifiers. The OP amplifier has a resistor R1 at its inverting input terminal as shown in FIG. 1, and the non-inverting input terminal is grounded. The feedback loop is provided with a loop resistor Rf from the output terminal to the inverting input terminal.

In the pair 210 of the current-voltage converter 200 configured as described above, the current generated by the diode D1 of the photodetector 100 divided into two is converted into a constant voltage, and the converted voltage is converted into an error. It is provided to one input terminal of the detector 300.

In addition, the other pair 220 of the current-voltage converter 200 also converts the current generated from one diode D2 of the photodetector 100 divided into a constant voltage, and converts the current into a constant voltage. It is provided to the other input terminal of the error detection unit 30.

At this time, the voltage provided from the current-voltage converter 200 is output as a product of the loop resistance Rf with respect to the current I generated in one diode, and its phase is inverted. That is, the output voltage is output as -I * Rf.

The error detector 300 includes a differential amplifier having two input terminals and one output terminal.

When the voltages provided by the two sets of current-voltage converters 210 and 220 are respectively input to two input terminals of the error detector 300, the error detector 300 may input two inputs input by the current-voltage converters 210 and 220. Amplify the difference voltage between voltages. At this time, the generated voltage is a tracking error signal, which indicates the degree to which the laser beam deviates from the tracks at regular intervals of the optical disk.

The phase compensator 40 compensates for the phase of the focusing error signal generated by the error detector 300, amplifies it, and outputs it as a drive control signal for driving the driver 50.

The driver 50 generates a drive signal for driving the tracking actuator coil by the drive control signal output from the phase compensator 40, and the focusing actuator coil is driven by the drive signal generated by the driver 50.

By driving the actuator coil, the objective lens (not shown) moves left and right, and by the movement of the objective lens, the signal surface of the optical disc is adjusted to be located within a certain depth of focus of the laser beam.

However, even if the tracking error signal is detected as 0 by performing the tracking servo as described above, an offset voltage is generated due to the inclination of the disk, the characteristics of the op amp, the characteristics of the photodiode, and the like. As it is included, each time the optical disc is mounted in the optical disc player, a process of measuring and adjusting the offset voltage is required.

Therefore, in the related art, such offsets are measured and adjusted for a predetermined section at the initial stage of mounting the optical disk.

However, in the related art, since the offset is measured by only one predetermined section and the offset is adjusted, the offset level, which is different depending on the degree of warpage of the optical disc, cannot be sufficiently adjusted.

Accordingly, the present invention has been made in view of the above-described problems, and an object of the present invention is to sample a plurality of predetermined sections of all sections of an optical disc, and to adjust an offset level by using a tracking error signal and RF (Radio Frequecy). It is to provide an offset adjustment method of an optical disc player that can measure and adjust the measured offset level.

In order to achieve the above object, the present invention is to detect the amount of light reflected from the optical disk at the time of reproduction of the optical disk in the two-segmented photodiode, so that the difference between the RF signal generated from the sum of the detected light amount and the detected light amount An offset level adjustment method of an optical disc player for measuring and removing an offset level that is an error between a point where a tracking error signal becomes zero and an actual tracking point by using a tracking error signal, wherein the optical disc is divided into a plurality of sections. A first step of detecting a tracking error signal and an RF signal in each of the sections after dividing into a setting; A second step of comparing a plurality of RF signals detected in the first step with a tracking error signal, respectively, and measuring an offset level corresponding to each of the sections; A third step of performing tracking servo based on the detected offset level after detecting the offset level corresponding to the current playback position from the offset level measured in response to the respective sections when the optical disc is reproduced; It provides a method of adjusting the offset of the optical disc player comprising a.

1 is a block diagram showing a general tracking servo device;

2 is a block diagram of hardware for implementing the offset adjustment method according to the present invention,

3 is a flowchart illustrating an offset adjustment method according to the present invention;

4 is an exemplary diagram showing waveforms of tracking error signals in each section and each section of the optical disc for measuring the offset level according to the present invention;

<Description of the code | symbol about the principal part of drawing>

100: photodetector 200: current-voltage converter

300: error detection unit 400: an adder

500: offset detection unit 550: tracking servo device

600: microcomputer 700: storage unit

800: optical disc player 900: offset adjustment unit

Hereinafter, with reference to the accompanying drawings will be described in detail the present invention.

2 is a block diagram of hardware for implementing the offset adjustment method according to the present invention, the photodetector 100, the current-voltage converter 200, the error signal detector 300, the adder 400, the offset The detector 500, the tracking servo device 550, the microcomputer 600, the storage 700, the optical disc player 800, and the offset adjuster 900 are included.

Hereinafter, the function of each component member of the hardware for implementing the offset adjustment method according to the present invention, the photodetector 100, the current-voltage converter which is a component member of the general tracking servo device shown in FIG. (200), the error detector 300 has been described above and will be omitted.

First, the adder 400 adds two predetermined voltages output from the first current-voltage converter 210 and the second current voltage converter 220 to output an RF signal.

The offset detector 500 measures the value of the tracking error signal generated by the error detector 300 at the highest point of the RF signal, and measures the offset level as a difference between the measured value and 0 and provides it to the microcomputer 600.

The tracking servo device 550 performs tracking servo by using the tracking error signal output from the error detector 300.

The microcomputer 600 controls the overall operation of the optical disc player 800 and controls the offset adjuster 500 to adjust the offset level.

The storage unit 700 stores preset position data of the offset measurement section for measuring the offset level and stores the offset level measured in each preset section, and the offset adjuster 900 of the microcomputer 600 By controlling, the offset is adjusted by supplying the tracking servo device 550 with a predetermined offset voltage capable of canceling the offset level.

The optical disc player 800 performs the original operation of the optical disc such as the reproduction of the optical disc under the control of the microcomputer 600.

The offset adjustment method of the optical disc player according to the present invention made of the above-described structural members will now be described with reference to FIGS. 3 and 4.

3 is a flowchart illustrating an offset adjustment method according to the present invention, and FIG. 4 is an exemplary view showing waveforms of tracking error signals in each section and each section of the optical disc for measuring the offset level according to the present invention.

First, when the optical disc is loaded into the optical disc player 100 (S 10), the microcomputer 600 refers to the position data of the offset measurement section preset in the storage unit 700, and tracks for a predetermined time in the first section. The optical disc player 100 is controlled to detect an error.

Under the control of the microcomputer 300, the optical disc player 100 moves an internal optical pickup unit (not shown) to the first offset measurement section and irradiates a laser beam of a predetermined level to the signal surface of the optical disc. At this time, a certain amount of the laser beam is reflected on the optical disk, and the two divided photodetectors D1 and D2 detect the laser beams reflected as described above, and generate a predetermined current corresponding to the detected light amount.

The first current-voltage converter 210 converts a current generated from one diode D1 of the two-part photodetector 100 into a constant voltage, and converts the converted voltage into an error detector 300 and an adder ( 400 to one input terminal.

In addition, the second current-voltage converter 220 also converts a current generated by one diode D2 of the photodetector 100 divided into a constant voltage, and converts the converted voltage into an error detector 300. ) And the other input of the adder 400.

When the voltages provided by the two sets of current-voltage converters 210 and 220 are respectively input to two input terminals of the error detector 300, the error detector 300 may input two inputs input by the current-voltage converters 210 and 220. The difference voltage between the voltages is amplified and provided to the offset detector 500 (S20). At this time, the generated voltage is a tracking error signal, which indicates the degree to which the laser beam deviates from the tracks at regular intervals of the optical disk.

Meanwhile, the adder 400 adds two voltages provided by the two sets of current-voltage converters 210 and 220, outputs the added voltage as an RF signal and provides the offset voltage to the offset detector 500 (S 30).

The offset detection unit 500 checks the highest point of the RF signal (indicated by a, b, c ... in FIG. 4) provided from the adder 400 in step S 30, and checks the error detection unit ( After measuring the value of the tracking error signal (indicated by A, B, C ... in FIG. 4) provided from 300), the offset level is measured by the difference between the value of the tracking error signal and 0 ( S 40) provided to the microcomputer 600.

Using this method, the offset is detected only at the point where the RF signal peaks, so that the offset level can be measured more quickly.

The microcomputer 600 stores the offset level provided from the offset detection unit 500 in the storage unit 700 together with the preset position data of the first section (S 50), and then presets it with reference to the storage unit 700. The offset measurement section is searched for (S 60).

As a result of the search in step S 60, if there is position data for the next offset measurement section preset in the storage unit 700, the microcomputer 600 controls the optical disc player 800 to perform the above-described offset measurement section in step S 20. Repeat step S60. (S 70),

On the other hand, if there is no position data for the next offset measurement section preset in the storage unit 700 as a result of the search at step S60, the microcomputer 600 allocates a TOC (Read-in) to the read-in area of the mounted optical disc. Table Of Contents) controls the optical disc player 800 to read the information.

The optical disc player 800 reads TOC information from the lead-in area of the optical disc under the control of the microcomputer 700, and then waits for input of a key signal (S80).

Subsequently, when a play key signal is generated by a key input unit (not shown) and the generated play key signal is applied to the microcomputer 600 (S90), the microcomputer 600 uses the optical disk mounted in the optical disk player 800. Control the optical disc player 800 to control.

The optical disc player 800 plays back the optical disc mounted therein under the control of the microcomputer 600 (S100), and provides the microcomputer 600 with information on the current playback position, and the microcomputer 600 stores the storage unit. With reference to the position data of the first offset measurement section stored in 700, it is determined whether the current playback position provided by the optical disc player 800 reaches the first offset measurement section.

As a result of the determination in S 110, when the current playback position of the optical disc player 800 reaches the first offset measurement section (S 120), the microcomputer 600 adjusts the offset level of the first offset measurement section stored in the storage unit 700. The offset adjusting unit 900 is controlled to adjust the offset level of the tracking servo device 550 according to the withdrawal and withdrawal offset level, and the offset adjusting unit 900 controls the first offset measurement section under the control of the microcomputer 600. The offset level of the tracking servo device 550 is adjusted by supplying a predetermined offset voltage to the tracking servo device 550 to compensate for the offset level.

Thereafter, the microcomputer 300 determines whether the storage unit 400 has location information on the next offset measurement section (S 140), and if there is a next offset section, the system repeats the operation S 120 in step S 100. Control the panel and stop the offset adjustment if there is no next offset section.

As described above, according to the present invention, after measuring the offset voltage for each predetermined section for all sections of the optical disk mounted in the optical disk player, and then adjust the offset level for each section according to the measured offset level, optical disk The tracking servo of the player can be performed accurately, thereby improving the reliability of the optical disc player.

Claims (1)

When reproducing the optical disc, the amount of light reflected from the optical disc is detected by a two-divided photodiode, and a tracking error signal is generated by using a tracking error signal generated from the difference between the detected light amount and the RF signal generated from the sum of the detected light amounts. In the offset level adjustment method of an optical disc player for measuring and eliminating an offset level that is an error between a point where 0 becomes 0 and a point where actual tracking coincides. A first step of dividing and setting the optical disc into a plurality of sections, and detecting a tracking error signal and an RF signal in each section; A second step of comparing a plurality of RF signals detected in the first step and a tracking error signal, respectively, and measuring a value of an offset level corresponding to each of the sections; A third step of performing tracking servo based on the detected offset level after detecting the offset level corresponding to the current playback position from the offset level measured in response to the respective sections when the optical disc is reproduced; Offset adjustment method of the optical disc player comprising a.

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