KR100640745B1 - Definition improvement circuit of a digital television through input signal limitation - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit for improving image quality of a digital television through input signal limitation, and includes: a front end for changing a scanning method of an input signal; and a synchronization selector for detecting the number of horizontal lines and vertical synchronization in the output signal of the front end. And a microcomputer which compares the number of horizontal lines detected by the synchronization selecting unit with the vertical synchronization and the current operation mode, and outputs a control signal for changing the operation mode when the vertical synchronization is out of the frequency range of the current operation mode. It is composed of a back end to change the operation mode under the control of the microcomputer to display the screen, and when the NTSC signal is input while the 2Fv is selected and operated, it is operated as 1Fv of the NTSC method, so that vertical synchronization is achieved. It is possible to prevent the deterioration of the image quality by preventing the operation of NTSC type 2Fv of 120Hz.

PAL, NTFS, 1Fv, 2Fv

Description

DEFINITION IMPROVEMENT CIRCUIT OF A DIGITAL TELEVISION THROUGH INPUT SIGNAL LIMITATION}             

1 is a circuit diagram of an image quality improvement of a digital television through input signal limitation according to the present invention;

2 is a signal processing flowchart of a microcomputer in FIG.

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

1: micro computer 2: front end

3: Sync selector 4: Back end

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image quality improvement circuit of a digital television by limiting input signals. In particular, an image can be displayed with the best image quality by restricting an input signal in a digital television capable of simultaneously receiving 1 Fv and 2 Fv in PAL and NTSC. The present invention relates to an image quality improvement circuit of a digital television through an input signal restriction adapted to make it suitable.

In general, digital televisions can receive both PAL and NTSC broadcast signals.

At this time, the PAL method can be divided into 1Fv having a frequency of 50Hz and 2Fv having 100Hz, and the NTSC method can be divided into 1Fv having a frequency of 60Hz and 2Fv having a frequency of 60Hz.

In the PAL method, 2Fv having a frequency of 100 Hz has better image quality than 1Fv. In the NTSC method, 1Fv having a frequency of 60 Hz has better image quality than 2Fv.

Digital televisions receiving the broadcast signals classified as described above are classified into being able to receive only 1Fv, capable of receiving 2Fv, and capable of receiving both 1Fv and 2Fv.

The conventional digital television capable of receiving both 1Fv and 2Fv through a single input port could select only 1Fv or 2Fv among the received signals.

When 1Fv is selected, the NTSC method with excellent image quality and PAL signal with poor image quality are deteriorated. If 2Fv is selected, the PAL signal with excellent image quality and NTSC method with poor image quality are received. There was a problem that the image quality is degraded.

In other words, if the user is watching 100Hz in PAL mode while 2Fv is selected and the NTSC broadcast signal is received, the user should watch in 120Hz, which is 2Fv. There was no problem.

Accordingly, the present invention has been created to solve the above-described problems, and 2Fv and NTSC of PAL method which provides relatively excellent picture quality in digital televisions capable of receiving both 1Fv and 2Fv of PAL method and NTSC method. It is an object of the present invention to provide an image quality improvement circuit of a digital television by limiting an input signal capable of improving the image quality of a digital television by selecting 1Fv.

The present invention for achieving the above object is a front end for changing the scanning method of the input signal, a synchronization selector for detecting the number of horizontal lines and vertical synchronization in the output signal of the front end, and the detection in the synchronization selector A microcomputer which compares the number of horizontal lines and the vertical synchronization with the current operation mode, and outputs a control signal for changing the operation mode when the vertical synchronization is out of the frequency range of the current operation mode; According to the present invention, the display device may include a back end configured to display a screen by changing an operation mode.

SUMMARY OF THE INVENTION The present invention is directed to the provision of a circuit capable of selecting Fv with better image quality in each system in a digital television capable of receiving both PAL and NTSC broadcast signals.

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

First of all, in adding reference numerals to the components of each drawing, it should be noted that the same components have the same reference numerals as much as possible even if displayed on different drawings.

Also, in the following description, numerous specific details, such as specific processing flows, are set forth in order to provide a more general understanding of the invention, and it is to be understood that the invention may be practiced without these specific details. It will be obvious to them.

In addition, detailed description of well-known functions and structures which are determined to unnecessarily obscure the subject matter of the present invention will be omitted.

1 is a circuit diagram for improving image quality of a digital television through input signal limitation according to the present invention. As shown in FIG. 1, a microcomputer 1 and a composite video signal CVBS for controlling each unit are received according to an embedded program. The front end (FRONT-END, 2) for converting the brightness (Y) and the color difference signals (Cb, Cr) of the sequential scanning method, and the front end (2) and the image signals (Y, Pb, Pr) are input to the micro A synchronization selector 3 for selectively synchronizing and outputting the synchronization according to the control of the computer 1, and a back-end 4 for receiving an output signal of the synchronization selector 3 and displaying it on the screen; It is configured to include.

Hereinafter, the configuration and operation of the image quality improvement circuit of the digital television through the input signal limitation according to the present invention configured as described above will be described in more detail.

First, the front end 2 which receives the composite video signal CVBS converts a signal input by interlaced scanning into a sequential scanning method.

Table 1 below summarizes NTSC and PAL input signals and their vertical and horizontal signals.

NTSC NTSC PAL PAL 480i 480p 576i 576p unit 1H 15.734 31.5 15.634 31.25 KHz 1 V 60 60 50 50 Hz

In Table 1, i denotes interlaced scanning, and p denotes progressive scanning.

That is, the front end 2 converts to 480p or 576p when a broadcast signal of 480i or 576i is input.

In this state, when the operation mode is 2Fv, if the PAL type 576i is input, it is converted to 576p to watch at 100Hz. At this time, if NTSC type 480i is input, the image quality may be degraded by operating at 120Hz which is 480p.

To compensate for this, the microcomputer 1 receives the number of horizontal lines and vertical sync detected by the sync selector 3 for selecting the sync of the output signal of the front end 2, and is suitable for the operation mode of the current state. Determine if

2 is an embodiment of a signal processing flowchart of the microcomputer 1, in which the detected horizontal line number is 576 lines when the current operation mode is 2Fv, and maintains the current operation mode when the horizontal synchronization is 100 Hz. If the number of horizontal lines is 480 in the NTSC system and the vertical synchronization is 120 Hz, the operation mode is converted to NTSC 1Fv.

Through this operation, the image quality of the screen displayed through the back end 4 may be improved.

As described above, the present invention prevents the operation of the NTSC 2Fv whose horizontal synchronization is 120 Hz, thereby making it possible to obtain clearer image quality.

As described above, in the present invention, when the NTSC signal is input while the 2Fv is selected, the present invention operates the NTSC type 1Fv, thereby preventing the vertical synchronization from operating in the NTSC type 2Fv having 120 Hz, and flickering lines. This prevents the deterioration of the image quality.

Claims (2)

A front end for changing the scanning method of an input signal, a synchronization selector for detecting horizontal lines and vertical synchronization in the output signal of the front end, a horizontal line and vertical synchronization and current operation detected by the synchronization selector Compare the modes, and if the vertical synchronization is out of the frequency range of the current operation mode, the micro computer outputs a control signal for changing the operation mode, and the screen for changing the operation mode under the control of the micro computer to display the screen. An image quality improvement circuit for digital television through input signal limitation, characterized in that consisting of an end. The method of claim 1, The microcomputer maintains the current operation mode when the number of horizontal lines detected by the synchronization selector is 570 when the operation mode is 2Fv, and the vertical synchronization is 100 Hz, and when the number of horizontal lines detected is 480, when the vertical synchronization is 120 Hz, 1Fv. And a control signal for switching to an operation mode.

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