KR100797466B1 - Digital TV - Google Patents

Abstract

The present invention relates to a digital TV that can prevent screen shaking during an analog reception. The present invention relates to a video switching that receives a digital composite video signal, an analog composite video signal, or an external composite video signal and switches one of the composite video signals. And a clock control unit for digitally converting the OSD signal output from the digital processing unit and compensating for the clock of the OSD signal when receiving an analog broadcast, mixing the converted OSD with the composite video signal output from the video switching unit. An A / D color decoder for separating vertical and horizontal syncs from the mixed signal, an interpolator for interpolating the composite video signal output from the A / D color decoder, and deflecting the interpolated composite video signal to display an RGB signal D / A deflection processing unit displayed on the screen, corresponding to the digital or analog broadcast reception It includes a microcomputer that controls the entire system to output the digital signal and compensates the clock of the composite video signal and the OSD signal during analog reception. By using the signal and the system clock, the image quality can be improved by preventing the OSD screen from shaking or jitter during analog reception.

Digital TV / OSD / Jitter

Description

Digital TV {Digital TV}

1 is a block diagram of a digital TV according to the prior art.

2 is a block diagram of a digital TV according to the present invention.

3 is a detailed block diagram of an A / D color decoder.

Explanation of symbols for main parts of the drawings

A: digital processing unit

1: COFDM section 2: System clock generator

3: central processing unit 4: MPEG and graphics

5: digital output unit 11: microcomputer

B: analog processing unit

12: tuning and detection unit 13: video switching unit

14: A / D color decoder 15: interpolator

16: D / A deflection processor 17: clock switching unit

C: clock control

31: A / D converter 32: shift register

33: inverter

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to digital TVs, and more particularly, to digital TVs that prevent screen shaking when receiving an analog broadcast.

FIG. 1 is a block diagram of a digital TV according to the prior art, in which a digital broadcast signal (Digital RF) is applied and tuned and COFDM demodulation generates a transport stream (hereinafter, referred to as a TP stream). A COFDM (Corded Orthogonal Frequency Division Multiplexing) unit 1, a central processing unit 3 that receives the TP stream according to the clock of the clock generator 2 and separates it into data such as audio and video, and a microcomputer 11 Tuning and detection unit 12 for tuning and detecting analog broadcast signal (Analog RF) and outputting analog composite video signal (A_CVBS) under the control of a), and receiving and encoding video data from the central processing unit (3). And an MPEG and graphics unit 4 for outputting a digital RGB (Red / Green / Blue) (D_RGB) signal and a digital composite video signal (D_CVBS).

The digital composite video signal D_CVBS of the MPEG and graphics unit 4 and the external composite video signal SC_CVBS and the analog composite video signal of the tuning and detection unit 12 are controlled by the microcomputer 11. A video switching unit 13 that receives (A_CVBS) switching control and outputs any one composite video signal (CVBS), the digital RGB signal (D_RGB) of the MPEG and graphics unit (4) and the composite video signal ( A / D color decoder 14 that receives and decodes and outputs the CVBS), an interpolator 15 that interpolates and outputs an output signal of the A / D color decoder 14, and the interpolator 15 And a D / A deflection processor 16 which deflects the output signal and displays it on the screen as an RGB signal.

Referring to the operation of the digital TV according to the prior art configured as described above are as follows.

Digital TVs used in Europe can simultaneously receive digital and analog terrestrial signals, and in order to achieve this, the digital TVs are tuned, selectively processed, and displayed on the screen by analog analog signals (Analog RF) and digital broadcast signals (Digital RF). It must include a function.

First, when receiving a digital broadcast, when the digital broadcast signal is applied, the COFDM unit 1 selects only a broadcast of a specific channel by the user's selection, and generates a TP stream by performing COFDM demodulation.

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

The MPEG and graphics unit 4 encodes the video data applied from the CPU 3 using an RGB encoder provided therein to convert the digital RGB signal D_RGB and the digital composite video signal D_CVBS. Output

In this case, the MPEG and the graphic unit 4 may receive an external clock as well as a fixed internal clock and distinguish clocks according to an analog input or a digital input of a digital TV.                         

On the other hand, when receiving an analog broadcast, the tuning and detection unit 12 tunes and detects an analog broadcast signal under the control of the microcomputer 11 and outputs the analog composite video signal A_CVBS.

Subsequently, the video switching unit 13 controls the digital composite video signal D_CVBS and the external composite video signal SC_CVBS of the MPEG and graphics unit 4 and the tuning and detection unit under the control of the microcomputer 11. The analog composite video signal A_CVBS of 12) is applied to switch control to select one composite video signal and output the final composite video signal CVBS.

In detail, the video switching unit 13 converts the digital composite video signal D_CVBS to the A / D color decoder 14 when receiving digital broadcasting, and the analog composite video signal A_CVBS when receiving analog broadcasting. Upon receiving a separate external signal, the external composite video signal SC_CVBS is output as the final composite video signal CVBS.

The A / D color decoder 14 receives, decodes and outputs the digital RGB signal D_RGB and the composite video signal CVBS of the MPEG and graphics unit 4.

Then, the interpolator 15 outputs the output signal of the A / D color decoder 14 by line interpolation at 100 Hz, and the D / A deflection processor 16 outputs the output signal of the interpolator 15. Is deflected to display the RGB signal on the screen.

In the related art, when an analog broadcast is received, an analog broadcast signal is selected, and an analog composite video signal (A_CVBS) input through the tuning and detection unit 12 and the digital OSD signal generated by the MPEG and graphic unit 4 during the OSD processing. Is mixed in the A / D color decoder 14 to display the screen according to the digital system clock.

In addition, the A / D color decoder 14 generates a horizontal and vertical synchronizing signal using a mixed signal of the OSD signal and the analog composite video signal A_CVBS.

Accordingly, the digital TV according to the prior art uses a digital system clock even when receiving an analog broadcast and generates a horizontal and vertical synchronizing signal from a mixed signal of the analog composite video signal (A_CVBS) and the digital OSD signal. The synchronization of the screens is often inconsistent, causing the OSD screen to shake violently and jitter.

The present invention has been made to solve the above problems of the prior art, and an object of the present invention is to use a fixed system clock when receiving digital broadcasts and to synchronize using a system clock and a synchronization signal obtained from analog when receiving analog broadcasts. It's about providing a digital TV to help you decide.

The digital TV according to the present invention for achieving the above object comprises a digital processing unit for receiving a digital broadcast signal and outputting a digital composite video signal, and an analog processing unit for receiving an analog broadcast signal and outputting an analog composite video signal; In a digital TV capable of receiving digital and analog broadcasts, a video switching unit for switching any one composite video signal by receiving the digital composite video signal, the analog composite video signal or an external composite video signal, and the digital processing unit at the time of analog broadcast reception. A clock control unit for digitally converting the OSD signal outputted from the digital signal and compensating for the clock of the OSD signal, and mixing the converted OSD with the composite video signal output from the video switching unit and performing vertical and horizontal synchronization on the mixed signal. A / D knife to separate A decoder, an interpolator for interpolating the composite video signal output from the A / D color decoder, a D / A deflection processor for deflecting the interpolated composite video signal and displaying the RGB signal on a screen, and receiving a digital or analog broadcast. According to the present invention, the microcomputer is configured to control the overall system to output a corresponding clock and to compensate for the clocks of the composite video signal and the OSD signal during analog reception.

Hereinafter, a digital TV according to the present invention will be described with reference to the accompanying drawings.

2 is a block diagram showing the configuration of a digital TV according to the present invention.

As shown, the digital TV according to the present invention receives a digital broadcast signal and outputs a digital composite video signal (D_CVBS) and a digital broadcast signal (A_CVBS). In the digital TV having an analog processing unit (B) for receiving digital and analog broadcasts, the digital composite video signal (D-CVBS), the analog composite video signal (A_CVBS) or the external composite video signal (SC_CVBS) are applied. A video switching unit 13 for receiving and switching any one composite video signal, Clock control unit for digitally converting the OSD signal output from the digital processing unit (A) when receiving an analog broadcast and to compensate for the clock of the OSD signal (C) mixing the converted OSD with the composite video signal output from the video switching unit 13 and vertically from the mixed signal. An A / D color decoder 14 for separating flat syncs, an interpolator 15 for interpolating the composite video signal output from the A / D color decoder 14, and RGB by deflecting the interpolated composite video signal. D / A deflection processing unit 16 to display on the screen as a signal, to control the whole system to output the corresponding clock according to the digital or analog broadcast reception, and to compensate for the clock of the composite video signal and the OSD signal when receiving the analog It is comprised including the microcomputer 11.

Then, the system clock generator 2 for generating the clock, the clock switch unit 17 for switching the clock output from the A / D color decoder 14 and the clock output from the system clock generator 2 It is configured to further include.

In this case, the digital processing unit A receives and tunes a digital broadcast signal, performs COFDM demodulation, and outputs a COFDM unit 1 for generating a transport stream, and outputs from the clock switch unit 17. A central processing unit (3) for receiving the transport stream according to the clock, and separating the data into audio and video data; and receiving and encoding the video data output from the central processing unit (3). MPEG and graphic unit 4 for outputting a composite video signal, and the analog processing unit (B) is composed of a tuning and detection unit (12).

In addition, the clock control unit C converts the OSD signal output from the MPEG and graphic unit 4 into a digital form and receives the converted OSD signal to the A / D color decoder 14 when an analog broadcast is received. A shift register for compensating the clocks of the A / D converter 31, the OSD signal output from the A / D converter 31, and the composite video signal output from the A / D color decoder 14. 32) and an inverter 33 for providing the output of the A / D color decoder 14 according to the system specification of the digital TV.

Referring to the operation of the digital TV according to the present invention configured as described above, when the digital broadcast signal (Digital RF) is applied first, the COFDM unit 1 tunes the broadcast signal of a specific channel according to the user's selection and the tuned COFDM demodulation of the broadcast signal generates a TP stream.

The CPU 3 outputs a system clock (13.5 MHz) output from the system clock generator 2 or a clock (13.5 MHz) output from an A / D color decoder 14 that processes an analog broadcast signal. According to the TP stream is authorized audio. The data is separated into data such as video and output, and the clock is output as a 40.5 MHz clock signal.

In addition, the MPEG and graphics unit 4 encodes the video-MPEG data applied from the central processing unit 3 by using an RGB encoder provided therein, so that the RGB signal (RGB) and the digital composite video signal (D_CVBS) Outputs the corresponding OSD signal under the control of the microcomputer 11 to insert the OSD.

Next, the tuning and detecting unit 12 tunes and detects an analog broadcast signal (Analog RF) under the control of the microcomputer 11 and outputs an analog composite video signal A_CVBS.

Here, the video switching unit 13 is a digital composite video signal D_CVBS output from the MPEG and graphics unit 4, an analog composite video signal A_CVBS output from the tuning and detection unit 12, or externally. The external composite video signal SC_CVBS is applied to switch and control the composite video signal to output the final composite video signal CVBS.

For example, the video switching unit 13 supplies the digital composite video signal D_CVBS to the A / D color decoder 14 when digital broadcasting is selected under the control of the microcomputer 11.

At this time, the A / D color decoder 14 receives the digital RGB signal (D_RGB) output from the MPEG and graphic unit 4 as shown in FIG. The unit 21, an RGB / YUV converter 22 for converting the output of the RGB A / D converter 21 into luminance and chroma signals, and outputting the same; An A / D converter 23 for converting and outputting a decoder, a decoder 24 for decoding an output signal of the A / D converter 23 and converting the signal into a luminance-to-saturation signal, and the decoder 24 and the RGB A mixing unit 25 for mixing the output signals of the / YUV conversion unit 22, and an H / V synchronization separating unit 26 for separating and outputting vertical and horizontal synchronization from the output signal mixed in the mixing unit 25 and The clock generator 27 generates a 13.5 MHz clock according to the output signal of the H / V sync separator 26 and the output signal of the mixer 25. Figure-luminance by controlling the saturated color - consists of a YUV control unit 28 for outputting a saturation (YUV) signals, and to determine the brightness and color saturation, and color of the vertical and horizontal synchronizing signals and the screen necessary to the deflection.

The H / V sync separator 26 embedded in the A / D color decoder 14 configured as described above performs vertical and horizontal sync in the composite video signal CVBS output from the video switch 13. Separately outputted, which is also applied to the line clock generator 27 to output a 13.5MHz line clock.

Here, the analog signal is received through the A / D converter 31 of the clock controller C and converted into a digital signal form under the control of the microcomputer 11 during analog reception, and the shift register 32 is The MPEG and graphics unit 4 receives a predetermined signal D_FB to synchronize the RGB signal with the composite video signal.

As described above, unlike the conventional digital TV, the RGB signal RGB and the composite image signal CVBS are mixed through the mixing unit 25, and the vertical horizontal synchronization signal H / V and the clock are mixed in the mixed signal. A signal is output and the operation of the central processing unit 3 and the MPEG and graphics unit 4 is controlled. When the analog broadcast is received, the RGB signal is input directly after passing through the clock control unit C without directly inputting the A / D color decoder 14.

Then, in order to synchronize the composite image signal CVBS with the RGB signal, an output signal of the shift register 32 is input to the A / D color decoder 14 via the inverter 33 to synchronize the synchronization signal. To control.

Accordingly, the present invention uses a fixed system clock when receiving digital broadcasts, and determines synchronization using a system clock and a synchronization signal obtained from an analog composite video signal during analog reception. In addition, the analog signal may be mixed and output through clock compensation and A / D conversion before mixing the OSD signal into the composite video signal.

The digital TV according to the present invention described above uses a fixed system clock when receiving digital broadcasts, and by using a synchronization signal and a system clock obtained from analog when receiving analog signals to prevent shaking or jitter of the OSD screen during analog reception. There is an effect that can improve the image quality.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the present invention.

Therefore, the technical scope of the present invention should not be limited to the contents described in the embodiments, but should be defined by the claims.

Claims (3)

In the digital TV capable of receiving digital and analog broadcasts having a digital processing unit for receiving a digital broadcast signal and outputting a digital composite video signal, and an analog processing unit for receiving an analog broadcast signal and outputting an analog composite video signal, A video switching unit configured to switch one of the composite video signals by receiving the digital composite video signal, the analog composite video signal, or an external composite video signal; A clock controller which controls to digitally convert an OSD signal output from the digital processor and compensate for a clock of the OSD signal when an analog broadcast is received; An A / D color decoder for mixing the converted OSD with the composite video signal output from the video switching unit and separating vertical horizontal sync from the mixed signal; An interpolator for interpolating a composite video signal output from the A / D color decoder; A D / A deflection processor for deflecting the interpolated composite video signal and displaying the RGB signal on a screen; And a microcomputer for controlling the entire system to output a corresponding clock according to a digital or analog broadcast reception, and for controlling a clock of the composite video signal and the OSD signal during analog reception. The method of claim 1, A system clock generator for generating the clock; And a clock switch unit for switching a clock output from the A / D color decoder and a clock output from the system clock generator. The method of claim 1, The clock control unit The A / D converter for converting the OSD signal output from the digital processor into a digital form and outputting the converted OSD signal to the A / D color decoder when an analog broadcast is received; And a shift register for compensating for the clocks of the OSD signal output from the A / D converter and the composite video signal output from the A / D color decoder.

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