KR100222868B1 - The adjustable circuit for front porch and back porch term of color television - Google Patents

Abstract

The present invention relates to the front porch and back porch period adjustment circuit of a color television that controls unnecessary video signals corresponding to the front porch and back porch of a color television having a width wider than a ratio are not displayed on the screen.

The front porch and back porch period adjusting circuit of the color television comprises a sync separator for separating the horizontal sync signal included in the video signal input to the television system, and inputting a horizontal sync signal outputted from the sync separator to perform a blank erase. A controller for outputting a control signal and a clock signal, a window generator for reading a clock signal output from the controller and outputting a control signal for setting the front porch and the back porch of the video signal only within a specific time interval; A front porch adjusting unit for outputting a control signal for controlling the start and end of the front porch section of the video signal based on a retrace control signal of the window generator and an output signal of the window generator, and a period of the front porch controlled by the front porch adjusting unit. Front porch period control unit for shortening and the return canceller of the control unit A back porch adjusting unit for outputting a control signal for controlling the start and end of the back porch section of the video signal for the output signal of the window generator, and a back for shortening the period of the back porch controlled by the back porch adjusting unit. And a adder configured to output a signal for controlling the front porch and the back porch of the video signal by adding an output signal of the porch period controller and the front porch period controller and the back porch period controller.

Description

Front TV and Back Porch Period Control Circuit for Color TV

1 is a front porch and back porch period adjustment circuit of a conventional color television.

2 is a waveform diagram for showing the level of a video signal of a conventional color television.

3 is a front porch and back porch period adjusting circuit of a color television according to the present invention.

* Explanation of symbols for main parts of the drawings

11: sync separation unit 12: control unit

13: window generator 14: front porch adjustment unit

15: front porch adjustment section 16: back porch adjustment section

17: back porch period adjustment unit 18: the adder

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a front porch and back porch period adjustment circuit of a color television. More particularly, the front porch and back porch period included in a video signal tuned in a color television can be shortened. Color television front porch and back porch period adjustment circuit.

1 is a front porch and back porch period adjustment circuit diagram of a conventional color television. Referring to FIG. 1, the front porch and back porch period adjusting circuit of a conventional color television includes a sync separator 1 for separating a horizontal sync signal included in a video signal input to a television system, and the sync separator ( A control unit 2 for outputting a blanking control signal and a clock signal by inputting a horizontal synchronizing signal output from 1), and a clock signal output from the control unit 2 to read out the front of the image signal only within a specific time interval. A front porch section of the video signal by a window generator 3 which outputs a control signal for setting a porch and a back porch, a blanking control signal of the controller 2, and an output signal of the widow generator 3. Front porch adjustment unit 4 for outputting a control signal for controlling the start and end of the control, the blanking control signal of the control unit 2 and the exit of the window generator 3 To the signal, a back porch adjusting unit 5 for outputting a control signal for controlling the start and end of the back porch section of the video signal, and the output signals of the front porch adjusting unit 4 and the back porch adjusting unit 5 are added. And an adder for outputting a signal for controlling the front porch and the back porch of the video signal.

The front porch and back porch period adjusting circuits of the conventional color televisions configured as described above also refer to a composite video signal corresponding to one screen as shown in FIG. 2 (a) when a video signal is applied to the color television (see also the second (b)). ), The front porch (①-②) and the back porch (③-④) are set around the horizontal synchronizing signal (see also the second (d)) between the image signal and the next screen.

The front porch (①-②) ensures that there is no influence of the image signal in the period of the horizontal synchronizing signal, and the back porch (③-④) has sufficient margin for the return period required when the electron beam returns from right to left of one scanning line. It is for.

That is, in the mixed video signal inputted to the color television, the horizontal synchronizing signal is separated by the sync separating unit 1, and the control unit 2 receives the blanking signal DC such as the clock signal CLK and the second (c) diagram, respectively. Output

The window generator 3 determines the clock signal CLK output from the control unit 2 and outputs the signals PC and BC for setting the front porch and the back porch, the front porch adjusting unit 4 and the back porch adjusting unit 5. Is applied to. At this time, the front porch adjusting unit 4 and the back porch adjusting unit 5 are applied. At this time, the blanking signal D.C output from the control unit 2 is applied to the front porch adjusting unit 4 and the back porch adjusting unit 5, respectively.

Therefore, as shown in FIG. 2 (e), the video signal corresponding to the time when the blanking signal is applied does not appear on the screen of the color television.

Here, in general, the front porch is about 1.75 Using a clear pulse of the degree, the back porch is about 2.3 Use a pulse for deletion.

However, in the recent field of color television technology, a 4: 3 picture is reproduced as much as possible by reproducing the video signal of the portion intersecting the retrace sound signal applied to the front porch of the video signal, that is, the video signal corresponding to both ends of one screen. Width is about 1 than ratio There is an active research and use of color televisions that provide longer screens.

In this case, the front porch and the back porch have a long period of time, causing unnecessary images to appear at both ends of the screen.

An object of the present invention has been made in view of the above problems, and the front porch and back porch period of a color television which can prevent unnecessary video signals from appearing at both ends of the screen by shortening the front porch and back porch period of a color television. To provide an adjustment circuit.

In order to achieve the above object, the present invention provides a blanking control signal for separating a horizontal sync signal included in an image signal input to a television system and a horizontal sync signal output from the sync separator. And a control unit for outputting a clock signal, a window generator for reading a clock signal output from the control unit and outputting a control signal for setting the front porch and the back porch of the video signal only within a specific time interval. A front porch adjusting unit for outputting a control signal for controlling the start and end of the front porch section of the video signal by an erase control signal, an output signal of the window generator, and a short period of the front porch controlled by the front porch adjusting unit. Front porch period control unit and the return line of the control unit A back porch adjusting unit for outputting a control signal for controlling the start and end of a back porch section of the video signal by an output signal of the window generator, and a short period of the back porch controlled by the back porch adjusting unit. And a adder configured to output a signal for controlling the front porch and the back porch of the video signal by adding output signals of the back porch period controller and the front porch period controller and the back porch period controller.

Hereinafter, with reference to the accompanying drawings will be described in detail the configuration, operation and effects of the present invention.

3 is a front porch and back porch period adjusting circuit of a color television according to the present invention.

Referring to FIG. 3, the front porch and back porch period adjusting circuit of the color television according to the present invention includes a sync separator 11 for separating a horizontal sync signal included in an image signal input to a television system, and the sync separator. A control unit 12 for outputting a blanking control signal and a clock signal by inputting a horizontal synchronizing signal output from a negative unit; and a front porch of the image signal only within a specific time interval by reading a clock signal output from the control unit 12; And a window generator 13 outputting a control signal for setting a back porch, a blanking control signal of the controller 12, and an output signal of the window generator 13 to start the front porch section of the video signal. Front porch adjustment unit 14 for outputting a control signal for controlling the end and the end, and the front porch of the front porch control unit 14 Controlling the start and end of the back porch section of the video signal by the front porch period control section 15 for shortening the interval, the blanking control signal of the control section 12, and the output signal of the window generator 13; A back porch adjusting unit 16 for outputting a control signal, a back porch period controlling unit 17 for shortening the period of the back porch controlled by the back porch adjusting unit 16, and the front porch period controlling unit 15 and the back porch And an adder 18 for outputting a signal for controlling the front porch and the back porch of the video signal by adding the output signal of the period control unit 17.

The present invention configured as described above further includes the front porch period control section 15 and the back porch period control section 17 shown in FIG. 3 as compared to the front porch and back porch period adjustment circuit of the conventional color television.

Accordingly, the front porch period control unit 15 and the back porch period control unit 16 adjust the start and end of the front porch and the back porch set by the front porch adjusting unit 14 and the back porch adjusting unit 16 while viewing the color television screen. Avoid unnecessary video signals appearing on the screen.

According to the present invention as described above there is an effect that can prevent the appearance of unnecessary video signals that may occur on the screen having a longer width than the existing 4: 3 aspect ratio.

Claims (1)

A control unit for separating a horizontal synchronizing signal included in an image signal input to a television system, a control unit for inputting a horizontal synchronizing signal output from the synchronizing separation unit to output a blanking control signal and a clock signal; A window generator that reads a clock signal outputted from and outputs a control signal for setting the front porch and the back porch of the image signal only within a specific time interval, a blanking control signal of the controller, and an output signal of the window generator A front porch adjustment unit for outputting a control signal for controlling the start and end of the front porch section of the video signal, a front porch period control unit shortening a period of the front porch controlled by the front porch adjustment unit, and retrace of the control unit An erase control signal and an output scene of the window generator. A back porch adjustment unit for outputting a control signal for controlling the start and end of the back porch section of the video signal, a back porch period control unit shortening a period of the back porch controlled by the back porch adjustment unit, and the front porch period And an adder which adds an output signal of a control unit and a back porch period control unit to output a front porch of the video signal and a signal for controlling the back porch.