KR100253738B1 - Method for controlling focus bias in optical disc player - Google Patents

Abstract

PURPOSE: An adjusting method for focus bias in an optical disk player is provided to adjust focus bias in considering changed rate of jitter amount. CONSTITUTION: An optical disk is mounted on an optical disk player. A focus bias voltage F(A) for detecting a maximum positive jitter amount and a focus bias voltage F(B) for detecting a maximum negative jitter amount are stored in a store unit. Then, a focus bias adjust unit transfers a focus bias voltage F(A') adjusted from the focus bias voltage F(A) to an actuator coil of the optical disk player. The optical disk player reproduces an optical disk for supplying a reproduced signal to a jitter amount detect unit. Information about the jitter amount is stored in a memory. The focus bias adjust unit a maximum focus bias voltage F(B') to an optical pickup unit. The optical disk is reproduced for supplying a reproduced signal to the jitter amount detect unit. Then, a jitter amount is detected for supplying information about the jitter amount to the system control unit. A positive jitter amount change amount is calculated by subtracting F(A') from F(A), and a negative jitter amount change amount is calculated by subtracting F(B') from F(B). Then, the positive value is compared with the negative value.

Description

How to adjust the focus bias 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 a focus bias adjustment method of an optical disc player capable of adjusting a focus bias value in response to a change rate of jitter amount detected when an optical disc is played.

In general, optical disc players include compact disk players (CDPs), laser disk players (LDPs), compact disk graphic players (CDGPs), and video compact disk players (VCDPs). video compact disk player) has been developed and widely used. Also, recently, a digital video disk (DVD) using MPEG-2 moving picture compression technology and a digital video disk player for playing the same have been developed. It can record and play back gigabytes (GB) of data including moving images on a 12cm optical disc such as a CD, and it is also designed to be compatible to play current CDs and VCDs.

Such an optical disc player has been developed to record and reproduce image and audio data on a semi-permanent optical disc as audio and video media have developed.

Such an optical disc player reproduces an image and / or audio recorded on an optical disc and outputs it through a screen and / or a speaker, and has a higher signal-to-noise ratio than conventional image and / or audio reproducing apparatus, resulting in better image quality and / or Or it can reproduce the signal with sound quality, it does not generate noise due to irregular reproduction and modulation, very low distortion, no ghost and random access, so it is rapidly developed and widely distributed. There is a trend.

On the other hand, in order for the optical disc player to correctly read the program recorded on the optical disc, the signal surface of the optical disc should be located within the depth of focus of the laser beam irradiated by the optical pickup. And performed the same function. Here, the focus bias adjustment means adjusting the signal plane of the optical disc so as to be located within a constant depth of focus of the laser beam of the optical pickup unit, and focus servo is a state in which the signal plane of the optical disc is located within the constant focus depth of the laser beam of the optical pickup unit. The focus is adjusted to correspond to the minute variation of the optical disc.

If the focus bias adjustment is not performed correctly, the signal level of the reproduction signal is detected to be smaller than the original signal, and an error occurs in data reading. Such an error is commonly referred to as jitter.

Therefore, in order to reduce jitter in the related art, after detecting the amount of jitter corresponding to each focus bias value while changing the focus bias value, the focus bias is adjusted to the focus bias value when the detected jitter amount is minimum. .

However, in such a conventional method, even if the focus bias is adjusted to a focus bias value that minimizes jitter, the state of the optical disc or the system changes every time the optical disc player is driven, so that the focus bias is not accurately adjusted. There was this.

Accordingly, the present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to focus on detecting a positive maximum jitter amount using a detected amount of jitter according to a change in a focus bias voltage. The focus bias is adjusted to the average value of the focus bias voltage at which the voltage and negative maximum jitter amount are detected, but the focus bias is adjusted in consideration of the rate of change of the jitter amount according to the change of the focus bias at positive and negative values. It is to provide a method of adjusting the focus bias of an optical disc player configured to be adjustable.

In order to achieve the above object, in the present invention, an optical disc player for adjusting a focus bias using the detected jitter amount in an optical disc player in which the jitter amount previously detected corresponding to each of a plurality of focus bias voltages is stored. In the bias adjustment method,

Detecting the jitter amount F (A ') after adjusting the focus bias by reducing a predetermined voltage preset to the focus bias voltage F (A) when a positive maximum jitter amount A of the jitter amount is detected. A first step of making; After adjusting the focus bias by increasing a predetermined voltage as in the first step to the focus bias voltage F (B) when a negative maximum jitter amount B of the jitter amount is detected, the jitter amount B ' Detecting a second step; Focus bias voltage F (A) when a positive maximum jitter amount A of the jitter amount is detected and focus bias voltage F (B) when a negative maximum jitter amount B is detected Calculating a mean focus bias voltage F (M) of Positive (+) and negative (−) values are calculated from the positive jitter amount change amount (a) and the negative jitter amount change amount (b) calculated in the third step detected in the first and second steps. Calculating a jitter amount change rate of After correcting the average focus bias voltage F (M) calculated in the third step to correspond to the positive and negative jitter change rates calculated in the fourth step, the modified focus bias voltage F ( And a fifth step of adjusting the focus bias with M ').

1 is a block diagram of hardware for implementing a focus adjusting method of an optical disc player according to the present invention;

2 is a graph illustrating jitter amount detection according to a change in a focus bias voltage;

3 is a detailed flowchart illustrating a focus bias adjustment method of an optical disc player according to the present invention;

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

100: key input unit 200: system control unit

300: optical disk player 400: jitter amount detector

500: focus bias adjustment unit

600: storage unit

The above and other objects and advantages of the present invention will become more apparent from the preferred embodiments described below with reference to the accompanying drawings.

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

2 is a block diagram of hardware for implementing a focus bias adjustment method of an optical disc player according to the present invention, and includes a key input unit 100, a system control unit 200, an optical disc player 300, a jitter amount detection unit 400, The focus bias adjustment unit 500 and the storage unit 600, and their respective functions are as follows.

First, the key input unit 100 includes a plurality of function keys including a power key, and generates and provides a predetermined key signal corresponding to a user's key operation to the system controller 200.

The system controller 200 controls overall operations of the optical disc player 300 in response to signals provided by the key input unit 100 and the respective component members of the optical disc player 300, and in particular, changes in positive jitter amount. (a) and a negative jitter amount change (b) are calculated to control the focus bias adjustment unit 500 to perform focus bias adjustment corresponding to the calculated value.

The optical disc player 300 includes an optical pickup unit (not shown) and a focus servo unit (not shown), and performs various operations of the optical disc player, such as playback, under the control of the system control unit 200. In particular, the system is driven in the regeneration mode under the control of the system control unit 200 to provide a predetermined reproduction signal to the jitter amount detection unit 400.

The jitter amount detection unit 400 detects the jitter amount from the reproduction signal provided from the optical disc player 300 and provides it to the system control unit 200.

The focus bias adjustment unit 500 is a kind of bias voltage supply unit, and by providing the predetermined bias voltage to the optical pickup unit (not shown) provided in the optical disc player 300 under the control of the system control unit 200, Focus bias adjustment is performed so that the focus of the objective lens and the focus in the focusing error signal coincide.

The storage unit 400 presets the jitter amount detected by each of the plurality of focus bias voltages in a table. At this time, it is preferable that the detected jitter amount in each of the focus bias voltages is detected through a plurality of experiments.

Hereinafter, a process of implementing the focus bias adjustment method of the optical disc player according to the present invention in hardware including the constituent members performing the above-described functions will be described with reference to FIG. 2 with reference to FIG.

2 is a graph showing the jitter amount corresponding to the change in the focus bias voltage, where A is the positive maximum jitter amount, A 'is the jitter amount when the focus bias is reduced by a predetermined voltage, and B is The negative maximum jitter amount, B 'is the jitter amount when the focus bias is reduced by a predetermined voltage, a is the positive jitter amount change, and b is the negative jitter amount change amount. .

3 is a detailed flowchart illustrating a focus bias adjustment method of an optical disc player according to the present invention.

First, when the optical disc is mounted on the optical disc player 300 (S 10), the system controller 200 may provide information on the amount of jitter previously detected at each of the plurality of focus bias voltages stored in a table in the storage unit 600. Search and extract the focus bias voltage F (A) at which the positive maximum jitter amount is detected and the focus bias voltage F (B) at which the negative maximum jitter amount is detected. Store in a memory (not shown). (S20)

Thereafter, the system controller 200 controls the focus bias adjuster 500 to adjust the focus bias to the focus bias voltage A ′ increased by a predetermined voltage from the focus bias voltage F (A) stored in step S20. The focus bias adjustment unit 500 provides the focus bias voltage F (A ′) to the actuator coil (not shown) of the optical pickup unit included in the optical disc player 300 under the control of the system control unit 200. Hereinafter, the focus bias voltage is provided to the actuator coil provided in the optical pickup unit, and a description thereof will be omitted (S30).

Thereafter, the system control unit 200 controls the optical disc player 300 to play the optical disc mounted in the optical disc player 300 for a predetermined time in order to detect the jitter amount.

The optical disc player 300 reads a reproduction signal from the optical disc by reproducing the optical disc for a predetermined time while the focus bias is adjusted to the focus bias voltage F (A ') under the control of the system controller 200, and then reading the read signal from the optical disc. The reproduction signal is provided to the jitter amount detection unit 400. (S 40) At this time, in the preferred embodiment of the present invention, a table of contents (TOC) section may be reproduced for jitter amount detection.

The jitter amount detection unit 400 received the reproduction signal from the optical disc player 300 detects the jitter amount J (A ') by the reproduction signal provided from the optical disc player 300, and the detected jitter amount J (A'). Information is provided to the system controller 200.

The system controller 300 stores the information on the jitter amount J (P) provided by the jitter amount detector 400 in an internal memory provided in the storage unit 600 or the system controller 200 (S 50), and then S 20. The focus bias adjusting unit 500 is controlled to adjust the focus bias from the focus bias voltage F (B) stored in the step to the focus bias voltage F (B ') increased by a predetermined voltage. The maximum focus bias voltage F (B ') is provided to the optical pickup unit provided in the optical disc player 300 under the control of the system controller 200 (S60).

Thereafter, the system control unit 200 controls the optical disc player 300 to play the optical disc mounted in the optical disc player 300 for a predetermined time in order to detect the jitter amount.

The optical disc player 300 reads the reproduction signal from the optical disc by reading the reproduction signal from the optical disc after the optical disc is reproduced for a predetermined time in a state in which the focus bias is adjusted to the focus bias voltage F (B ') under the control of the system control unit 200. The signal is provided to the jitter amount detector 400 (S 70).

The jitter amount detection unit 400 received the playback signal from the optical disk player 300 detects the jitter amount J (M) by the playback signal provided from the optical disk player 300, and detects the jitter amount J (M). Information is provided to the system controller 200. (S80)

Subsequently, the system control unit 200 subtracts the focus bias voltage F (A ') detected in step S50 from the focus bias voltage F (A) stored in S20 to change the positive jitter amount (a). Negative jitter amount change b is calculated by subtracting the focus bias voltage F (B ') detected in step S80 from the focus bias voltage F (B) stored in S20. S 90)

When the step S 90 is finished, the system controller 200 again compares the positive jitter amount change a with the negative jitter amount change amount b calculated in step S 90. S 100)

As a result of the comparison in step S 100, when the amount of jitter change (a) is greater than the negative amount of change in jitter amount (b), the system control unit 200 stores the focus bias voltages F (A) and F ( The average focus bias voltage F (M) of B) is multiplied by the positive and negative jitter change rate b / a, and the focus is adjusted to the calculated focus bias voltage F (M '). The bias adjustment unit 500 is controlled, and the focus bias adjustment unit 500 provides the focus bias voltage F (M ') to the optical pickup unit provided in the optical disc player 300 under the control of the system control unit 200. S 110)

On the other hand, if the comparison result of the step S100, the jitter amount change (a) is smaller than the negative (-) jitter amount change (b), the system control unit 200 stores the focus bias voltage F (A) stored in step S20 Multiplying the average focus bias voltage F (M) of F and B by a positive (+) and negative (-) jitter amount change rate a / b, and focus bias is calculated using the calculated focus bias voltage F (M '). The focus bias adjusting unit 500 is controlled to adjust, and the focus bias adjusting unit 500 provides the focus bias voltage F (M ′) to the optical pickup unit provided in the optical disc player 300 under the control of the system control unit 200. (S 120)

According to the present invention as described above, by adjusting the focus bias automatically in response to the rate of change of the positive (+) and negative (-), the convenience and reliability can be improved in adjusting the focus bias. It works.

Claims (2)

A focus bias adjustment method of an optical disk player for adjusting focus bias using the detected jitter amount in an optical disk player in which jitter amounts previously detected corresponding to a plurality of focus bias voltages are stored, Detecting the jitter amount F (A ') after adjusting the focus bias by reducing a predetermined voltage preset to the focus bias voltage F (A) when a positive maximum jitter amount A of the jitter amount is detected. A first step of making; After adjusting the focus bias by increasing a predetermined voltage as in the first step to the focus bias voltage F (B) when a negative maximum jitter amount B of the jitter amount is detected, the jitter amount B ' Detecting a second step; Focus bias voltage F (A) when a positive maximum jitter amount A of the jitter amount is detected and focus bias voltage F (B) when a negative maximum jitter amount B is detected Calculating a mean focus bias voltage F (M) of Positive (+) and negative (−) values are calculated from the positive jitter amount change amount (a) and the negative jitter amount change amount (b) calculated in the third step detected in the first and second steps. Calculating a jitter amount change rate of After correcting the average focus bias voltage F (M) calculated in the third step to correspond to the positive and negative jitter change rates calculated in the fourth step, the modified focus bias voltage F ( And M '), the fifth step of adjusting the focus bias. The jitter amount change rate according to claim 1, wherein the fifth step comprises: when the positive jitter amount change amount a is greater than the negative jitter amount change amount b, the jitter amount change rate is equal to the average focus bias voltage F (M). Multiply b / a to correct the focus bias voltage F (M '), and if the positive jitter amount change a is less than the negative jitter amount change b, then the average focus bias voltage F And (M) multiplying the jitter amount change rate a / b to correct the focus bias voltage F (M ').

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