KR980011320A - A playback signal compensation device of an optical disk player - Google Patents

Abstract

The present invention relates to an apparatus for compensating a reproduction signal of an optical disc player, and more particularly to a signal compensator composed of resistors (R1 and R2), a capacitor (C1) and a second automatic gain control (AGC) A first and a second bandpass filters 42 and 52, first and second peak detectors 44 and 54, first through fourth lowpass filters 35 and 54, a first AGC amplifier 40, first and second bandpass filters 42 and 52, And low pass filters (46, 56, 58, 60), which cause damage to the disc due to deterioration of properties and inaccuracy in storage during the disc making process, So that the reproduction can be performed smoothly.

Representative figure: The second figure

Description

A playback signal compensation device of an optical disk player

FIG. 1 is a schematic block diagram of a typical optical disk player; FIG.

FIG. 2 is a schematic block diagram of an optical disc player adopting a reproducing signal compensating apparatus according to the present invention; FIG.

FIG. 3 is a detailed block diagram of the signal compensation unit shown in FIG. 2; FIG.

4 is a circuit diagram of a band-pass filter, a peak detector and a low-pass filter shown in Fig. 2; Fig.

DESCRIPTION OF THE REFERENCE NUMERALS

10, 20: optical pickup unit 12, 30: RF amplifier unit

14: digital signal processor 16: MPEG decoder

33, 42: AGC amplifier section 35: signal compensating section

43, 52: BPF 44, 54: peak detector

46, 56, 58, 60: LPF 48: Microcomputer

C: Capacitor L: Coil

D: optical disk D1: diode

Q: Transistor R: Resistor

The present invention relates to an optical disc player, and more particularly, to an optical disc player capable of compensating a level of a high-frequency signal in a reproduction signal due to an error in a state of an optical disc and an error in a manufacturing process, And a reproduction signal compensation apparatus.

As audio and video media evolve, an optical disk player has been developed which records audio and / or video signals on an optical disk having a diameter of 12 cm and then reproduces the audio and / or video signals. Such an optical disc player reproduces video and / or audio digitally recorded on an optical disc and outputs the reproduced video and / or audio through a screen and / or a speaker, and has a higher signal-to-noise ratio than conventional video and / It is possible to reproduce a signal with good image quality and / or sound quality, to prevent noise due to irregular reproduction and modulation, to have a very small amount of distortion (idstrotion), no ghost (virtual) Which is in widespread use.

On the other hand, in such optical disks, digital video and audio data representing video and / or audio is recorded on the optical disk with a predetermined flaw called a pit. These pits generally have a width dl 0.4 to 0.5 mu m in the case of a compact disc (CD) or a video compact disc (VCD), and nine stages in the pit length 3T to 11T (where T is the length of one clock pulse .

In the case of a CD or a VCD, the clock pulse frequency is 4.3218 MHz. Therefore, in the case of a disc in which the linear velocity is 1.25 m / s, T becomes about 0.2892 mu m (T = 1.25 / 4.3218) (In the case of 3T) and a maximum of 3.1815 占 퐉 (in the case of 11T), the interval between the rows of pits is 1.6 占 퐉, and the height of the pits is about 0.1 占 퐉. As a result, a radio frequency (RF) signal read out from the disc during reproduction of the optical disc is composed of 3T to 11T components and is distributed in a frequency band of 196KHz to 720KHz, and the RF signal has a signal level of about 1.0Vpp ± 0.2 V. Meanwhile, FIG. 1 is a schematic block diagram of a conventional optical disk player.

The optical pickup unit 10 executes an optical pickup from the disc D and converts the picked up signal into an electrical signal and outputs the electrical signal to the RF / servo signal processing unit 12. The RF / A spindle motor (not shown) for amplifying a signal provided from the optical pickup 12 and outputting the amplified signal to the digital signal processor 14 and processing the tracking and focus servo signals according to the signal to rotate the disk D, (10).

The digital signal processing unit 14 provides the RF signal provided from the RF / servo signal processing unit 12 to the MPEG decoder 16 through a digital signal processing and an error correction process, Decodes the signal provided from the signal processing unit 14 into audio and video signals based on the MPEG compression format, and outputs it to an audio signal processing unit (not shown) and a video signal processing unit (not shown).

On the other hand, when reproducing a general audio disc on which only audio signals are recorded, that is, a CD, the audio signal processed by the digital signal processing unit 14 as a digital signal is directly output to the audio signal processing unit.

However, when the disk surface is damaged due to carelessness of the disk storage and characteristics deterioration is severe during the disk manufacturing process, when the reproduction is performed in the conventional optical disk player as shown in FIG. 1, the voltage level of the RF signal becomes the reference level, 1.0 Vp-p ± 0.2 V or lower and the level of the high-frequency signal is lowered, so that the video and / or audio may be temporarily damaged or the reproduction may become impossible.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a method and an apparatus for recording information on a disc, And to compensate the reproduction signal so that the reproduction can be performed smoothly.

According to an aspect of the present invention, there is provided an optical pickup comprising: an optical pickup unit for executing an optical pickup from a disc to convert a picked up signal into an electrical signal and outputting the signal; And the RF amplifier unit amplifies and amplifies the amplified RF signal, and when the level of the reproduced RF signal is lower than a predetermined reference level and the level of the RF signal is lowered, A signal compensator for compensating for a level of a high frequency signal among RF signals provided from the RF amplifier unit; and a second compensator for compensating for a level of the RF signal provided from the RF amplifier unit, An automatic gain control amplifier unit for generating an output signal of said first automatic gain control unit, A second band-pass filter for filtering and outputting a 3T signal corresponding to a high-frequency signal of the reproduction signal from an output signal of the first automatic gain control unit, A first peak detector for detecting a peak value from an output signal of the first band-pass filter, a second peak detector for detecting a peak value from an output signal of the second band-pass filter, a second peak detector for detecting the output of the first band- A first low-pass filter for converting a signal into a DC value; a second low-pass filter for converting an output signal of the second peak detector into a DC value; DC values from the microcomputer and outputting respective pulse width modulation signals according to the comparison result; A third low-pass filter for converting the pulse width modulation signal set by the output value of the first low-pass filter into a DC signal and providing it to the first automatic gain controller to control the gain of the automatic gain controller; And a second low pass filter for converting a pulse width modulated signal set by the output value of the second low pass filter into DC and providing the signal to the signal compensator to compensate the level of the high frequency signal, Pass filter.

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

2 is a block diagram of an optical disc player in which an apparatus for compensating a reproduced signal of an optical disc player according to a preferred embodiment of the present invention is implemented, and FIG. 3 is a detailed configuration diagram of the signal compensator 35 shown in FIG. 4 shows the first and second band-pass filters 42 and 52 shown in FIG. 2, first and first peak detectors 44 and 54 and first and second low-pass filters 46 and 56 Fig.

The preferred embodiments of the present invention will be described in detail with reference to FIG. 2, FIG. 3, and FIG. 4. As shown in FIG. 2, the apparatus for compensating a reproduction signal of an optical disc player according to the preferred embodiment of the present invention includes resistors R1 and R2, a capacitor C1, and a second automatic gain control (AGC) A first AGC amplifier 40, first and second band pass filters 42 and 52, first and second peak detectors 44 and 44, , 54, and first to fourth low-pass filters (46, 56, 58, 60).

The signal composed of the resistors R1 and R2, the capacitor C1 and the AGC amplifier section 33 is supplied to the disc D via the optical pickup section 20 and the RF amp section 30, The compensation unit 35 compensates the 3T signal, that is, the high-frequency signal by amplifying the gain according to the amplification control voltage previously applied from the fourth low-pass filter 60, and outputs it.

The first gain control unit 40 controls the gain of the signal amplifying unit 35 based on the amplification control voltage output from the third low-pass filter 58 and the high- The gain of the signal is amplified and controlled to compensate the 11T signal, that is, the entire level of the reproduction signal and output.

The first bandpass filter 42 filters the 11T signal from the output signal of the first automatic gain control amplifier 40 and outputs the 11T signal to the first peak detector 44. The first peak detector 44 And detects the peak value of the signal and provides it to the first low-pass filter 46.

The first low-pass filter 46 converts the peak value of the 11T signal provided from the first peak detector 44 into a DC (direct current) voltage, and provides the DC (direct current) voltage to the micom 48.

The second bandpass filter 52 filters the 3T signal from the output signal of the first automatic gain control amplifier 40 and outputs the 3T signal to the second peak detector 54, And detects the peak value of the signal and provides it to the second low-pass filter 56.

The second low-pass filter 56 converts the peak value of the 3T signal provided from the second peak detector 54 into a corresponding DC voltage and provides the DC voltage to the micom 48.

4, the first and second band-pass filters 42 and 52 are connected in parallel and in series with the transistor Q, the resistors R3 and R6, the coil L and the capacitor C2, And may be constituted by a first band pass filter 42 or a second band pass filter 52 according to the values of the respective elements R, L and C, and the first and second peak detectors 44 and 54 Is composed of a capacitor C3 and a diode D1 connected in series and a resistor R4 and a capacitor C4 connected in parallel to each other.

The first and second low-pass filters 46 and 56 are formed by connecting a resistor R5 and a capacitor C5 in parallel.

Referring again to FIG. 2, the Mearcom 48 includes a first AGC amplifier section 33 and a second AGC amplifier section 53 constituting the signal compensating section 35 according to the DC voltage supplied from the first and second low-pass filters 46 and 56, respectively. (PWM) signal for keeping the level of the output voltage of the 2AGC amplifier unit 40 constant above the reference level to the third low-pass filter 58 and the fourth low-pass filter 60 ).

The fourth low pass filter 60 converts the PWM signal provided from the microcomputer 48 into a DC voltage and applies it to the second AGC unit 40. The second AGC unit 42 receives the PWM signal from the low pass filter 60 And controls the degree of amplification according to the provided DC voltage so that the level of the 3T signal, which is a high frequency signal among the RF signals provided from the RF amplifier unit 30, is kept constant at a level at which reproduction can be performed.

The third low pass filter 58 converts the PWM signal provided from the microcomputer 48 into a DC voltage and applies the same to the first AGC unit 40. The first AGC unit 42 receives the PWM signal from the low pass filter 58 And compensates the 11T signal of the reproduction signal which is amplified by the RF amplifier unit 30 and compensated for the high frequency signal by the signal compensation unit 35 so that the entire level of the reproduction signal is converted to the reference Level.

The DC voltage output from the third low pass filter 58 is used as the gain amplification control voltage of the first AGC amplifier 40 and the output voltage of the fourth low pass filter 60 is supplied to the second AGC amplifier 33, Is used as a gain amplification control voltage.

Therefore, the first AGC amplifier section 40 and the second AGC amplifier section 33 control the overall level of the RF signal reproduced in accordance with the output signals of the third and fourth low-pass filters 58 and 60 and the amplification degree of the high- Thereby keeping the RF signal constant at a level at which reproduction can be performed.

When the VCD is reproduced, the reproduction signal is supplied to the MPEG decoder 16 through the digital signal processing unit 14 as shown in FIG. 1 through digital signal processing and error correction, and the MPEG decoder 16 16 decodes the digital signal provided from the digital signal processing unit 14 according to the MPEG format, that is, decompresses the digital signal, and outputs the digital signal to an audio and video digital / analog (D / A) converter (not shown).

Then, the video and audio signals are converted into analog signals, and after a predetermined process, they are output as complete audio with no error and displayed as an image.

When a general CD is reproduced, the digital signal is processed by the digital signal processor 14 and then directly supplied to an audio signal processor, processed as an audio signal, converted into an analog signal, and output through a speaker (not shown).

Therefore, even when the level of the RF signal reproduced during reproduction and the level of the high-frequency signal are lowered to a reproducible level or lower due to the deterioration of the characteristics and the damage to the disk due to insufficient storage during storage, The signal level can be kept constant above the reference value so that the reproduction can be performed smoothly.

While the present invention has been particularly shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the invention as set forth in the following claims.

Claims (1)

An optical pickup unit 20 for executing an optical pickup from a disc and converting the picked up signal into an electrical signal and outputting the electrical signal; and an optical pickup unit 20 for amplifying a signal provided from the optical pickup unit 20 to a predetermined level and outputting an amplified RF signal An optical disk player for compensating for a case where the voltage level of the RF signal to be reproduced is less than or equal to a predetermined reference level and the level of the high frequency signal is lowered when the reproducing operation is performed in the optical disc player including the RF amplifier unit 30 A signal compensator (35) for compensating a level of a high frequency signal among RF signals provided from the RF amplifier unit (30); A first automatic gain control amplifier unit 40 for compensating the entire level of the RF signal provided from the RF amplifier unit 30; A first band-pass filter (42) for filtering and outputting an 11T signal corresponding to the entire level of the reproduction signal from an output signal of the first automatic gain control unit (40); A second band pass filter (52) for filtering and outputting a 3T signal corresponding to a high frequency signal of the reproduction signal from an output signal of the first automatic gain control unit (40); A first peak detector (44) for detecting a peak value from an output signal of the first band-pass filter (42); A second peak detector 54 for detecting a peak value from the output signal of the second band-pass filter 52, a first low-pass filter 46 for converting the output signal of the first peak detector 44 into a DC value, Wow; A second low pass filter (56) for converting an output signal of the second peak detector (54) to a DC value; A microcomputer 48 for comparing the respective DC values provided from the first and second low-pass filters 46 and 56 with preset reference values and outputting respective pulse width modulated signals corresponding thereto; Converts the pulse-width modulated signal set by the output value of the first low-pass filter (46) among the pulse-width modulated signals output from the microcomputer (48) to DC, and provides it to the first automatic gain controller A third low-pass filter (58) for controlling an amplification degree of the automatic gain control unit; Converts the pulse width modulated signal set by the output value of the second low-pass filter (56) out of the pulse width modulated signals output from the microcomputer (48) to DC and provides the signal to the signal compensator (35) And a fourth low-pass filter (60) for causing the compensation unit (35) to compensate the level of the high-frequency signal. ※ Note: It is disclosed by the contents of the first application.