KR19990026859A - How to adjust the focus bias of the optical disc player - Google Patents

Abstract

The present invention relates to a method of adjusting a focus bias of an optical disc player, wherein a variable amount of focus bias voltage corresponding to a variation in jitter amount is pre-stored through a number of experiments, and thus the amount of focus bias is varied to detect jitter amount. By adjusting the focus bias automatically by using the detected jitter amount and the variable amount of the prestored focus bias voltage, the convenience and reliability of the focus bias can be improved.

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 variation in jitter amount detected during reproduction of an optical disc.

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, since each of the amount of jitter must be detected while adjusting the focus bias value in order to find the focus bias value that minimizes jitter, the time required to adjust the focus bias value is reduced. There was a big problem with consumption.

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 provide a focus bias adjustment method of an optical disc player that can automatically adjust the focus bias by using a deviation of the jitter amount according to the focus bias adjustment. To provide.

In order to achieve the above object, in the present invention, in the focus bias adjustment method of an optical disk player in which the focus bias of the optical disk player is adjusted so that the amount of jitter is minimum, the jitter amount J (p) is set in a state of being set to a predetermined focus bias. A first step of detecting and storing; A second step of detecting jitter amount J (M) after resetting the focus bias to an adjustable maximum focus bias; A third step of calculating the jitter amount deviation E of the jitter amount J (M) detected in the second step and the jitter amount J (p) detected in the first step; A fourth step of detecting the jitter amount J (p1) after adjusting the focus bias by a predetermined variable amount corresponding to the jitter amount deviation E; A fifth step of comparing the jitter amount J (p1) detected in the fourth step with the jitter amount J (p) detected in the first step; As a result of the comparison in the fifth step, if the jitter amount J (p) is greater than the jitter amount J (p1), the focus bias is set to the current focus bias value, and if the third step to fifth step is repeated, It provides a method of adjusting the focus bias of an optical disc player comprising a sixth step.

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

* Explanation of symbols for main parts of the drawings

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 300 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, is provided by the jitter amount detector 400. The focus bias adjuster 500 is adaptively controlled in accordance with the amount of jitter and the amount of change in the focus bias corresponding to the jitter amount stored in the storage unit 600.

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.

In the storage unit 400, a variable amount of the focus bias voltage is tabled according to the jitter amount deviation range, and preset. In this case, the variable amount of the focus bias voltage preset for each jitter amount deviation range may be 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 component members that perform the above-described function will be described with reference to FIG. 3.

2 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 in the optical disc player 300 (S 10), the system control unit 200 controls the focus bias adjustment unit 500 to adjust the focus bias to a predetermined basic focus bias voltage F (P), and focus The bias adjustment unit 500 provides a basic focus bias voltage F (P) preset by the control of the system control unit 200 to an actuator coil (not shown) of the optical pickup unit provided in the optical disc player 300. Hereinafter, the focus bias voltage is provided to the actuator coil provided in the optical pickup unit, and the description thereof will be omitted (S20).

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 reproducing the optical disc for a predetermined time under the control of the system controller 200, and then provides the read reproduction signal to the jitter amount detecting unit 400. (S30 In this case, in the preferred embodiment of the present invention, a table of contents (TOC) section may be reproduced for detecting jitter.

The jitter amount detection unit 400 received the reproduction signal from the optical disc player 300 detects the jitter amount J (P) by the reproduction signal provided from the optical disc player 300, and detects the jitter amount J (P). Information is provided to the system controller 200. (S40)

The system controller 300 stores the information on the jitter amount J (P) provided by the jitter amount detector 400 in an internal memory included in the storage unit 600 or the system controller 200, and then changes the amount of the focus bias voltage. The focus bias adjusting unit 500 is controlled to adjust the focus bias to the maximum voltage F (M), and the focus bias adjusting unit 500 sets the maximum focus bias voltage F (M) under the control of the system control unit 200. Provided to the optical pickup provided in the 300. (S 50)

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 reproducing the optical disc for a predetermined time in a state in which the focus bias is adjusted to the maximum focus bias voltage F (M) under the control of the system control unit 200, and then reading out the read signal. The signal is provided to the jitter amount detector 400.

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. (S60)

Subsequently, the system controller 200 subtracts the jitter amount J (P) stored in step S40 from J (M) for the jitter amount provided from the jitter amount detection unit 400 in step S60 to determine the jitter amount deviation E (S 70)

Thereafter, the system controller 200 refers to the table of the variable amount of the bias bias compared to the jitter amount deviation E stored in the storage unit 600 as shown in Table 1, and calculates the jitter amount deviation E calculated in step S 70. The focus bias adjusting unit 500 is controlled to adjust the focus bias by a variable amount S corresponding to the deviation range included, and the focus bias adjusting unit 500 corresponds to the deviation range under the control of the system controller 200. The focus bias voltage F (P1) whose focus bias is adjusted by the variable amount S is provided to the optical pickup unit provided in the optical disc player 300 (S80).

Jitter amount deviation (E) Focus Bias Variable Amount E≥a S1 a ＞ E≥b S2 b ＞ E≥c S3 c ＞ E≥d S4 -------- ---------

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 reading the reproduction signal from the optical disc by reproducing the optical disc for a predetermined time while the focus bias is adjusted by the variable focus bias voltage F (P1) under the control of the system controller 200. The reproduction signal is provided to the jitter amount detection unit 400. (S90)

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. (S100)

Thereafter, the system controller 200 compares the jitter amount J (P1) received from the jitter amount detector 400 at step S100 with the jitter amount J (P) stored at step S40 (S110).

As a result of the comparison in step S 110, if the jitter amount J (P1) is greater than the jitter amount J (P), the system control unit 200 recognizes that the current focus bias adjustment is optimal, and selects the focus via the current focus bias voltage. The focus bias adjustment unit 500 is controlled to adjust, and the focus bias adjustment unit 500 controls the system control unit 200 to adjust the current focus bias voltage F (P1) to the optical pickup player provided in the optical disc player 300. And maintain the current state. (S 120)

On the other hand, when the comparison result of step S 110 shows that the jitter amount J (P1) is smaller than the jitter amount J (P), the system control unit 200 determines that the focus bias is not correctly adjusted, and the jitter amount J (P1) is The overall optical disc player system is controlled to repeat steps S70 to S110 until the jitter amount J (P) is greater.

As described above, according to the present invention, by automatically setting the focus bias value corresponding to the focus bias deviation, in adjusting the focus bias, the convenience and reliability can be improved.

Claims (1)

In the focus bias adjustment method of an optical disc player which adjusts the focus bias so that the amount of jitter is minimum, A first step of detecting and storing the jitter amount J (p) in a state of being set to a predetermined focus bias; A second step of detecting jitter amount J (M) after resetting the focus bias to an adjustable maximum focus bias; A third step of calculating the jitter amount deviation E of the jitter amount J (M) detected in the second step and the jitter amount J (p) detected in the first step; A fourth step of detecting the jitter amount J (p1) after adjusting the focus bias by a predetermined variable amount corresponding to the jitter amount deviation E; A fifth step of comparing the jitter amount J (p1) detected in the fourth step with the jitter amount J (p) detected in the first step; As a result of the comparison in the fifth step, if the jitter amount J (p) is greater than the jitter amount J (p1), the focus bias is set to the current focus bias value, and if the third step to fifth step is repeated, And a sixth step of adjusting the focus bias of the optical disc player.