JP3360332B2 - Video signal processing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal processing apparatus suitable for use in a television receiver using a liquid crystal panel, and more particularly to character display on a liquid crystal panel for both the NTSC system and the PAL system. Related to improving the display when doing

[0002]

2. Description of the Related Art In a liquid crystal panel for both the NTSC system and the PAL system, the number of lines (5
25) are arranged. In such a liquid crystal panel, since the number of pixels in the horizontal direction corresponds to the number of lines in the NTSC system, a video signal in the NTSC system can be displayed as it is. When displaying a PAL video signal (625 lines), about 8
Lines are thinned out for each book. With this, NTS
A PAL video signal can be projected on a liquid crystal panel having the number of lines of the C system.

[0003]

However, in the prior art,
When a PAL video signal is projected on a liquid crystal panel having the number of lines of the NTSC system by thinning the lines in this way,
There is a problem that the character display by the character generator becomes difficult to see. That is, in the related art, the character line is thinned out together with the video signal to be projected. Therefore, the character CHR as shown in FIG.
When trying to display 1, the lines L1 and L2 are thinned out, and as shown in FIG. 4B, a character CHR2 lacking a character is displayed, making it difficult to see the display.

Accordingly, it is an object of the present invention to provide a PAL for a liquid crystal panel having the number of lines of the NTSC system by thinning out the lines.
It is an object of the present invention to provide a video signal processing device capable of preventing a character display from being difficult to see when a video signal of a system is projected.

[0005]

SUMMARY OF THE INVENTION The present invention provides a first method.
Video signal is input, and the input video signal of the first system is input.
Performs line thinning on the
The number of lines of the video signal of the first scheme is
Video signal of the second system having fewer lines than the video signal
Line number conversion means for converting the number of lines to
Signal and vertical sync signal, horizontal sync signal and vertical sync signal
A desired character is superimposed on the display position corresponding to the signal.
Character generating means for generating a display signal for
The horizontal synchronizing signal supplied to the character
Synchronize when reversing polarity of video signal every horizontal cycle
Signal and the delayed signal of the pulse signal
Gate with window signal obtained from
When the horizontal sync signal corresponds to the line decimated in the step
The gate is closed and the line number is converted by the line number conversion means.
From the video signal from which the
The combining means for combining the display signal of
Supplied and lines were thinned by the line number conversion means
The video signal is combined with the display signal from the character generator.
From the display panel that displays the image corresponding to the generated signal
A video signal processing device.

[0006]

When the video signal of the PAL system is projected on the liquid crystal panel of the number of lines of the NTSC system by thinning out the lines,
In the thinning line, the horizontal synchronization signal is not supplied to the character generator. As a result, missing characters can be prevented.

[0007]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a liquid crystal panel, and the number of pixels in the horizontal direction of the liquid crystal panel 1 corresponds to the number of lines in the NTSC system. The input terminal 2 is supplied with a PAL video signal. The PAL video signal is supplied to the decoder 3, and the three primary color signals R, G, and B are decoded. At this time, lines are thinned out about every eight lines. The output of the decoder 3 is supplied to the mix circuit 4.

[0008] A control signal from the microcomputer 5 is supplied to the character generator 6. The character generator 6 is supplied with the horizontal synchronizing signal HSync from the liquid crystal display 1 via the gate circuit 7 and the vertical synchronizing signal VSync. A character signal is generated from the character generator 6 based on a command from the microcomputer 5. This character signal is supplied to the mix circuit 4.

In the mixing circuit 4, the character signal from the character generator 6 is superimposed on the three primary color signals from the decoder 4. The output of the mix circuit 4 is supplied to the liquid crystal display 1. On the liquid crystal display 1, a screen based on the PAL video signal from the input terminal 2 is displayed, and a character generated by the character generator 6 is superimposed on the screen.

In one embodiment of the present invention, the character generator 6 supplies a horizontal synchronizing signal H
Sync is supplied. The gate circuit 7 prevents the horizontal synchronizing signal HSync from being supplied to the character generator 6 in the thinning line. The character generator 6 receives the horizontal synchronization signal HSync and generates a character signal.

The gate circuit 7 is configured as shown in FIG. In FIG. 2, a pulse signal FR is input to an input terminal 11.
P is supplied, and a horizontal synchronizing signal HSyn is
c is supplied. The pulse signal FRP is a signal for synchronizing when the polarity of the video signal to be sent to the liquid crystal panel 1 is inverted every H (H is a horizontal cycle).

The pulse signal FRP from the input terminal 11 is
The EX-OR gate 1
4 is supplied to one input terminal. The output of the delay circuit 13 is supplied to the other input terminal of the EX-OR gate 14. E
The output of the X-OR gate 14 is output to O
The signal is supplied to one input terminal of the R gate 16. A horizontal synchronization signal HSync is supplied from the input terminal 12 to the other input terminal of the OR gate 16. The output of the OR gate 16 is output from the output terminal 17.

As shown in FIG. 3A, the input terminal 12
A horizontal synchronization signal HSync is supplied. The input terminal 11 is supplied with a pulse signal FRP as shown in FIG. 3B. This pulse signal FRP is inverted every 1H, but does not change in the line where thinning is performed.

The input terminal FRP is delayed by a delay circuit 13, and the delay circuit 13 outputs a pulse signal as shown in FIG. 3C. The pulse signal FRP (FIG. 3B) and the delayed pulse signal (FIG. 3C) are supplied to the EX-OR gate 14, and the EX-OR gate 14 outputs a pulse signal as shown in FIG. 3D. EX-OR gate 14
Are inverted by the inverter 15. Inverter 1
From the output of 5, a window signal as shown in FIG. 3E is obtained.

This window signal is supplied to the OR gate 16. The horizontal synchronization signal Hsync from the input terminal 12 is gated by the OR gate 16. As a result, FIG.
As shown in F, the horizontal synchronization signal Hsy
nc is not output.

[0016]

According to the present invention, the line is thinned and N
When a PAL video signal is displayed on a liquid crystal panel having the number of lines of the TSC system, the horizontal synchronization signal is not supplied to the character generator in the thinned line. For this reason, character display is not skipped and character missing can be prevented.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of the present invention.

FIG. 2 is a block diagram showing a specific configuration of a gate circuit in one embodiment of the present invention.

FIG. 3 is a timing chart used for describing a specific configuration of a gate circuit in one embodiment of the present invention.

FIG. 4 is a schematic diagram used to explain a case where a character is displayed on a liquid crystal panel by a conventional processing circuit.

[Explanation of symbols]

 1 LCD panel 6 Character generator 7 Gate circuit

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04N 5/66 H04N 5/46 H04N 7/01 G09G 5/40

Claims (2)

(57) [Claims] 1. A video signal of a first system is inputted, and
The input video signal of the first format is written in
Performs the thinning process, and inputs the first method
The number of lines of the video signal of the first system.
Of the video signal of the second system having fewer lines than the
Line number conversion means for converting the horizontal synchronization signal
A direct sync signal is input, and the horizontal sync signal and the vertical sync signal are input.
Desired character is superimposed on the display position corresponding to the start signal.
Character generation means for generating a display signal for causing the horizontal synchronization signal to be supplied to the character generation means,
Synchronized when the polarity of the above video signal is inverted every horizontal cycle
And a signal obtained by delaying the pulse signal.
Gate with the window signal obtained from the
Horizontal synchronization signal corresponding to the line decimated by the
Video with the lines decimated by the gate means closed at the time of the signal and the line number conversion means
Signal and the display signal from the character generation means.
Synthesizing means for forming an output of said combining means is supplied, the line number conversion means
Video signal with lines decimated by
An image corresponding to a signal obtained by synthesizing the display signal from the generating means.
A video signal processing device, comprising: a display panel for displaying an image . 2. The video signal processing apparatus according to claim 1, wherein the video signal of the first system is a PAL system, and the video signal of the second system is an NTSC system.