KR100356508B1 - Digital television - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital television. In the related art, a digital television generates horizontal and vertical synchronizing signals using signals mixed in a mixing unit when receiving an analog broadcast signal, so that the synchronization of the on-screen display and the screen in the MPEG and the display unit is consistent. In some cases, the on-screen display trembles violently and there is a problem of jitter. In view of the above problems, the present invention is configured to generate a vertical horizontal separation pulse before the analog composite video signal, the external composite video signal or the digital video signal is mixed with the digital ALB signal. By generating a vertical horizontal sync separation pulse before mixing the composite video signal selected in, there is an effect to prevent the occurrence of jitter or jitter on the on-screen display when the analog broadcast is received.

Description

Digital television {DIGITAL TELEVISION}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to digital television, and more particularly, to a digital television that is adapted to prevent the shaking of a screen when receiving analog broadcasts.

FIG. 1 is a block diagram of a conventional digital television. As shown in FIG. 1, a COFDM unit (1, CORDED ORTHOGONAL FREQUENCY) which receives and tunes a digital broadcast signal (DIGITAL RF) and performs COFDM demodulation to generate a transport stream (TRANSPORT STREAM) DIVISON MULTIPLEXING); A central processing unit (3) for receiving the transport stream according to the system clock of the system clock generator (2) and separating the data into audio and video data; A tuning and detection unit 12 for tuning and detecting an analog broadcast signal ANALOG RF under the control of the microcomputer 11 and outputting an analog composite video signal ACVBS; An MPEG and graphic unit 4 receiving video data from the central processing unit 3 and encoding the same and outputting a digital RGB signal and a digital composite video signal DCVBS; According to the control of the microcomputer 11, the digital composite video signal DCVBS of the MPEG and graphic unit 4, the external composite video signal SCCVBS, and the analog composite video signal of the tuning and detection unit 12 ( A video switching unit 13 which receives ACVBS and performs switching control to output a final composite video signal CVBS; An analog-digital chroma decoder (14) for receiving and decoding the digital Algi ratio (D_RGB) signal and the composite video signal (CVBS) of the MPEG and graphic unit 4 and outputting the decoded signal; An interpolator (15) for interpolating and outputting the output signal of the analog digital chroma decoder (14); And a digital analog deflection processing unit 16 for deflecting the output signal of the interpolator 15 to display the ALG ratio signal RGB on the screen.

Hereinafter, the operation of the conventional digital television configured as described above will be described in more detail.

Digital televisions used in Europe are capable of receiving digital and analog terrestrial signals at the same time. In order to achieve this, digital televisions must include a function of tuning, selectively processing and displaying analog and digital broadcast signals on a screen.

First, when the digital broadcast signal DIGITAL RF is applied, the COFDM unit 1 selects only a broadcast of a specific channel by the user's selection, and performs a COFDM demodulation to generate a transport stream.

Subsequently, the central processing unit 3 receives the transport stream according to a system clock having a frequency of 13.5 MHz of the system clock generator 2, separates the data into audio and video data, and outputs 40.5 MHz. Outputs a clock signal.

At the same time, the tuning and detecting unit 12 tunes and detects the analog broadcast signal ANALOG RF under the control of the microcomputer 11 and outputs the analog composite video signal ACVBS.

Then, the MPEG and graphic unit 4 encodes the video data applied from the central processing unit 3 by using an AlGiB encoder provided therein, so that the digital RG signal and the digital composite video signal ( DCVBS).

Then, the video switching unit 13 controls the digital composite image signal DCVBS of the MPEG and graphic unit 4 and the external composite image signal SCCVBS and the tuning and detection under the control of the microcomputer 11. The analog composite video signal ACVBS of the unit 12 is applied to perform switching control to output the final composite video signal CVBS.

Next, the analog-digital chroma decoder 14 receives and decodes and outputs the digital image signal D_RGB and the composite video signal CVBS of the MPEG and graphic unit 4.

2 is a block diagram of the analog-digital chroma decoder 14 shown in FIG. 1. As shown in FIG. 21; An algibi / luminosity-saturation converter 22 for converting the output of the algibi analog-digital converter 21 into luminance and chroma signals; An analog-digital converter (23) for receiving the composite video signal (CVBS) and converting the analog-digital signal and outputting the analog-digital signal; A decoder (24) for decoding the output signal of the analog-to-digital converter (23) and converting it into a luminance-saturation signal; A mixing unit 25 for mixing and outputting the output signals of the decoder 24 and the ALGIE / LUMINE-Saturation Converter 22; A vertical horizontal synchronizing separator 26 for separating and outputting the vertical horizontal synchronizing unit from the output signal of the mixing unit 25; A line clock generator 27 for generating a 13.5 MHz line clock according to the output signal of the vertical horizontal synchronization separator 26; A luminance-saturation control unit 28 is configured to output luminance-saturation (YUV) signals by controlling luminance-saturation hue in the output signal of the mixing unit 25. Saturation and color will be determined.

The interpolator 15 then outputs the output signal of the analog digital chroma decoder 14 by interpolating the line at 100 Hz.

Then, the digital analog deflection processing unit 16 deflects the output signal of the interpolator 15 to display the ALG ratio signal RGB on the screen.

However, in the conventional digital television as described above, when the analog broadcast signal is received, the horizontal and vertical synchronizing signals are generated using the mixed signals in the mixing unit, so that the synchronization between the on-screen display and the screen in the MPEG and the display unit does not match. There is a problem in that the on-screen display is severely shaken and jitter occurs.

In view of the above problems, the present invention provides a digital television capable of determining synchronization by using a fixed clock signal when receiving a digital broadcast signal and using a system clock and a synchronization signal obtained from an analog broadcast signal. The purpose is.

1 is a block diagram of a conventional digital television;

Fig. 2 is a block diagram of the analog digital chroma decoder in Fig. 1;

3 is a block diagram of a digital television of the present invention;

4 is a block diagram of an analog-digital chroma decoder in FIG.

* Description of the symbols for the main parts of the drawings *

1: COFDM section 2: System clock generation section

3: central processing unit 4: MPA and graphics unit

11: Microcomputer 12: tuning and detector

13: Video switching unit 14: Analog digital chroma decoder

15: interpolator 16: digital analog deflection processing unit

17: Buffer 18: Clock Switch

21: Algibi analog-to-digital converter

22: Algi ratio / luminance-saturation conversion unit

23: analog digital conversion unit 24: decoder

25: Mixing section 26: Vertical horizontal synchronous separation section

27: line clock generation unit 28: luminance-saturation control unit

The above object is achieved by generating a vertical horizontal separation pulse before an analog composite video signal, an external composite video signal or a digital video signal is mixed with a digital ALG ratio signal, and with reference to the accompanying drawings of the present invention. When described in detail as follows.

3 is a block diagram of a digital television of the present invention. As shown therein, a COFDM unit (1, CORDED ORTHOGONAL) receives and tunes a digital broadcast signal (DIGITAL RF) and performs a COFDM demodulation to generate a transport stream (TRANSPORT STREAM). FREQUENCY DIVISON MULTIPLEXING); A central processing unit (3) for receiving the transport stream according to the system clock of the system clock generator (2) and separating the data into audio and video data; A tuning and detection unit 12 for tuning and detecting an analog broadcast signal ANALOG RF under the control of the microcomputer 11 and outputting an analog composite video signal ACVBS; An MPEG and graphic unit 4 receiving video data from the central processing unit 3 and encoding the same and outputting a digital RGB signal and a digital composite video signal DCVBS; According to the control of the microcomputer 11, the digital composite video signal DCVBS of the MPEG and graphic unit 4, the external composite video signal SCCVBS, and the analog composite video signal of the tuning and detection unit 12 ( A video switching unit 13 which receives ACVBS and performs switching control to output a final composite video signal CVBS; The digital image signal (D_RGB) and the composite video signal (CVBS) of the MPEG and graphic unit 4 are received and decoded and output, and the vertical and horizontal synchronization is directly separated from the composite video signal (CVBS). An analog digital chroma decoder 14 for generating a line clock of 13.5 MHz; A buffer 17 for buffering and outputting a 13.5 MHz line clock of the analog digital chroma decoder 14; A clock switch unit 18 for switching the output clock of the buffer 17 and the clock of the system clock generator 2 to apply to the central processing unit 3; An interpolator (15) for interpolating and outputting the output signal of the analog-digital chroma decoder (14); And a digital analog deflection processing unit 16 for deflecting the output signal of the interpolator 15 to display the ALG ratio signal RGB on the screen.

FIG. 4 is a block diagram of the analog-digital chroma decoder 14 in FIG. 3, and as shown in FIG. Wow; An algibi / luminosity-saturation converter 22 for converting the output of the algibi analog-digital converter 21 into luminance and chroma signals; An analog-digital converter (23) for receiving the composite video signal (CVBS) and converting the analog-digital signal and outputting the analog-digital signal; A decoder (24) for decoding the output signal of the analog-to-digital converter (23) and converting it into a luminance-saturation signal; A mixing unit 25 for mixing and outputting the output signals of the decoder 24 and the ALGIE / LUMINE-Saturation Converter 22; A luminance-saturation control unit 28 for controlling the luminance-saturation color from the output signal of the mixing unit 25 to output a luminance-saturation (YUV) signal; A vertical horizontal synchronizing separator 26 for separating and outputting the vertical horizontal synchronizing unit from the composite image signal CVBS; The line clock generator 27 generates a 13.5 MHz line clock according to the output signal of the vertical horizontal synchronization separator 26.

The operation of the digital television of the present invention configured as described above will be described below.

First, when a digital broadcast signal (DIGITAL RF) is applied, the COFDM unit 1 selects only a broadcast of a specific channel by a user's selection, and generates a transport stream by performing COFDM (CORDED ORTHOGONAL FREQUENCYDIVISON MULTIPLEXING) demodulation. do.

Then, the central processing unit 3 carries out the transport stream in accordance with the output clock of the system clock having an frequency of 13.5 MHz of the system clock generator 2 or the analog digital chroma decoder 14 which processes the analog broadcast signal. It is applied to separate the data such as audio, video, and the like, and outputs a clock signal of 40.5 MHz by multiplying the input clock by three times.

Next, the tuning and detecting unit 12 tunes and detects the analog broadcast signal ANALOG RF under the control of the microcomputer 11 and outputs the analog composite video signal ACVBS.

Then, the MPEG and graphic unit 4 encodes the video data applied from the central processing unit 3 by using an AlGiB encoder provided therein, so that the digital DGR signal and the digital composite video signal ( DCVBS), and an on-screen display or the like can be inserted.

Then, the video switching unit 13 is a digital composite video signal (DCVBS) of the MPEG and graphics unit 4 and the external composite video signal (SCCVBS) and the analog composite video signal of the tuning and detection unit 12 ( ACVBS) is applied to switch control to output the final composite video signal CVBS. At this time, the video switching unit 13 supplies a digital composite video signal DCVBS to the analog digital chroma decoder 14 when digital broadcasting is selected under the control of the microcomputer 11.

Then, the vertical and horizontal sync separator 26 embedded in the analog-digital chroma decoder 14 separates and outputs the vertical and horizontal syncs from the composite video signal CVBS, which is also applied to the line clock generator 27. This will generate a 13.5MHz line clock.

As described above, a clock frequency is directly obtained from an analog composite video signal (ACVBS), a digital composite video signal (DCVBS), or an external composite video signal (SCCVBS) before being mixed with the digital ALG ratio signal D_RGB. By using this to control the operation of the central processing unit 3, the MPEG and the graphic unit 4 to receive an analog broadcast it is possible to prevent the on-screen display, such as shaking or jitter.

At the same time, the algibi analog-to-digital converter 21 receives the digital algibi (D_RGB) signal and converts the analog-digital digital signal to the digital signal, and the algibi / luminance-saturation converter 22 receives the signal. The output of the digital converter 21 is converted into luminance and chroma signals and output.

Then, the analog-to-digital converter 23 receives the composite video signal CVBS and outputs the analog-to-digital converter, and the decoder 24 decodes the output signal of the analog-to-digital converter 23 to the luminance-saturation. Convert to a signal.

Then, the mixing unit mixes and outputs the output signals of the decoder 24 and the algi ratio / luminance-saturation converter 22, which controls the luminance-saturation color in the luminance-saturation control unit 28 to control the luminance-saturation. Outputs the (YUV) signal.

The interpolator 15 then outputs the output signal of the analog digital chroma decoder 14 by interpolating the line at 100 Hz.

Then, the digital analog deflection processing unit 16 deflects the output signal of the interpolator 15 to display the ALG ratio signal RGB on the screen.

As described above, the digital television of the present invention generates pulses for vertical and horizontal sync separation before the digital image signal and the composite video signal selected by the video switch unit are mixed, thereby causing a shaking phenomenon on the on-screen display when an analog broadcast is received. Or jitter can be prevented from occurring.

Claims (2)

A COFDM unit (1, CORDED ORTHOGONAL FREQUENCY DIVISON MULTIPLEXING) configured to receive and tune a digital broadcast signal (DIGITAL RF) and perform COFDM demodulation to generate a transport stream; A central processing unit (3) for receiving the transport stream according to the system clock of the system clock generator (2) and separating the data into audio and video data; A tuning and detection unit 12 for tuning and detecting an analog broadcast signal ANALOG RF under the control of the microcomputer 11 and outputting an analog composite video signal ACVBS; An MPEG and graphic unit 4 receiving video data from the central processing unit 3 and encoding the same and outputting a digital RGB signal and a digital composite video signal DCVBS; According to the control of the microcomputer 11, the digital composite video signal DCVBS of the MPEG and graphic unit 4, the external composite video signal SCCVBS, and the analog composite video signal of the tuning and detection unit 12 ( A video switching unit 13 which receives ACVBS and performs switching control to output a final composite video signal CVBS; The digital image signal (D_RGB) and the composite video signal (CVBS) of the MPEG and graphic unit 4 are received and decoded and output, and the vertical and horizontal synchronization is directly separated from the composite video signal (CVBS). An analog digital chroma decoder 14 for generating a line clock of 13.5 MHz; A buffer 17 for buffering and outputting a 13.5 MHz line clock of the analog digital chroma decoder 14; A clock switch unit 18 for switching the output clock of the buffer 17 and the clock of the system clock generator 2 to apply to the central processing unit 3; An interpolator (15) for interpolating and outputting the output signal of the analog-digital chroma decoder (14); And a digital analog deflection processing unit (16) for deflecting the output signal of the interpolator (15) to display an RGB signal on the screen. The digital digital chroma decoder (14) of claim 1, further comprising: an algibi analog-to-digital converting unit (21) for receiving an analog digital digital signal (D_RGB) and converting the analog-digital signal to output the analog-digital digital signal; An algibi / luminosity-saturation converter 22 for converting the output of the algibi analog-digital converter 21 into luminance and chroma signals; An analog-digital converter (23) for receiving the composite video signal (CVBS) and converting the analog-digital signal and outputting the analog-digital signal; A decoder (24) for decoding the output signal of the analog-to-digital converter (23) and converting it into a luminance-saturation signal; A mixing unit 25 for mixing and outputting the output signals of the decoder 24 and the ALGIE / LUMINE-Saturation Converter 22; A luminance-saturation control unit 28 for controlling the luminance-saturation color from the output signal of the mixing unit 25 to output a luminance-saturation (YUV) signal; A vertical horizontal synchronizing separator 26 for separating and outputting the vertical horizontal synchronizing unit from the composite image signal CVBS; And a line clock generator (27) for generating a 13.5 MHz line clock in accordance with the output signal of the vertical horizontal synchronizing separator (26).