JPH06165086A - Video signal processor - Google Patents

Abstract

PURPOSE:To prevent the missing of characters by supplying no horizontal synchronizing signal to a character generator in a thinning line in the case a PAL video signal is displayed on the liquid crystal panel with NTSC line numbers after thinning the line out. CONSTITUTION:The number of picture elements in the horizontal direction of a liquid crystal panel 1 corresponds to the number of lines in the NTSC system. A video signal in the PAL system is supplied to a decoder 3 and a line is thinned out when a three primary color signal is decoded. On the other hand, a horizontal synchronizing signal HSync is supplied through a gate circuit 7 to a character generator 6. The gate circuit 7 prevents the horizontal synchronizing signal from given to the character generator 6 in the thinning line. The character generator 6 accepts a horizontal synchronizing signal HSync and generates a character signal. In a mix circuit 4, the character signal is superimposed from the character generator 6 to the three primary color signal from the decoder 3.

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 device suitable for use in a television receiver using a liquid crystal panel, and more particularly to displaying a character on a liquid crystal panel for both NTSC and PAL systems. It is related to the improvement of 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 of the NTSC system (5
25 pixels) 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, the NTSC system video signal can be displayed as it is. When displaying a PAL video signal (625 lines), about 8
Lines are thinned out for each book. This allows NTS
It is possible to display a PAL system video signal on a liquid crystal panel having the number of lines of the C system.

[0003]

However, in the prior art,
When thinning lines in this way and displaying a PAL video signal on a liquid crystal panel having the number of NTSC lines,
This causes a problem that the character display by the character generator becomes difficult to see. That is, conventionally, the line of the character is thinned out together with the video signal to be displayed. Therefore, the character CHR as shown in FIG. 4A.
Attempting to display 1, the lines L1 and L2 are thinned out, and the character CHR2 with missing characters is displayed as shown in FIG. 4B, which makes the display difficult to see.

Therefore, an object of the present invention is to thin a line to form a liquid crystal panel of the number of lines of the NTSC system by PAL.
It is an object of the present invention to provide a video signal processing device capable of preventing the character display from being difficult to see when a video signal of a standard system is displayed.

[0005]

SUMMARY OF THE INVENTION The present invention provides a liquid crystal panel to which a video signal of the first system is supplied, in which lines are thinned to correspond to the number of lines of the video signal of the second system, and a liquid crystal. A character generator for superimposing a character on the screen of the panel, a means for suppressing the output of the character generator corresponding to the thinned lines, a video signal of the first system in which the lines are thinned, and the character generator It is a video signal processing device comprising a combining means for combining with an output.

[0006]

When the PAL system video signal is projected on the liquid crystal panel of the NTSC system line by thinning out the lines,
In the thinning line, the horizontal synchronizing signal is not supplied to the character generator. As a result, it is possible to prevent character loss.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 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, 1 is 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. A PAL video signal is supplied to the input terminal 2. The PAL video signal is supplied to the decoder 3 and the three primary color signals R, G, B are decoded. At this time, the line is thinned out every about 8 lines. The output of the decoder 3 is supplied to the mix circuit 4.

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 through 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 mix 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. A screen based on the PAL system video signal from the input terminal 2 is displayed on the liquid crystal display 1, and the character generated by the character generator 6 is superimposed on the screen.

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

The gate circuit 7 is constructed as shown in FIG. In FIG. 2, the pulse signal FR is applied to the input terminal 11.
P is supplied to the input terminal 12 and the horizontal synchronizing signal HSyn
c is supplied. The pulse signal FRP is a signal for synchronizing when the polarity of the video signal sent to the liquid crystal panel 1 is inverted every 1H (H is a horizontal period).

The pulse signal FRP from the input terminal 11 is
The EX-OR gate 1 is supplied to the delay circuit 13.
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 O
It is supplied to one input terminal of the R gate 16. The horizontal synchronizing 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.

At the input terminal 12, as shown in FIG. 3A,
The horizontal synchronization signal HSync is supplied. Further, the pulse signal FRP as shown in FIG. 3B is supplied to the input terminal 11. The pulse signal FRP is inverted every 1H, but it does not change in the thinning line.

The input terminal FRP is delayed by the 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
The output of is inverted by the inverter 15. Inverter 1
From the output of 5, the window signal as shown in FIG. 3E is obtained.

This window signal is supplied to the OR gate 16. The horizontal synchronizing signal Hsync from the input terminal 12 is gated by the OR gate 16. As a result, FIG.
As shown in F, in the thinning line, the horizontal synchronization signal Hsy
nc will not be 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 synchronizing signal is not given to the character generator in the thinning line. Therefore, the character display is not thinned out, and it is possible to prevent the character from being missing.

[Brief description of drawings]

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

FIG. 2 is a block diagram showing a specific configuration of a gate circuit according to an embodiment of the present invention.

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

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

[Explanation of symbols]

 1 Liquid crystal panel 6 Character generator 7 Gate circuit

Claims (2)

[Claims] 1. A liquid crystal panel to which a video signal of the first system is supplied, in which lines are thinned to correspond to the number of lines of the video signal of the second system, and a character is superimposed on the screen of the liquid crystal panel. And a means for suppressing the output of the character generator corresponding to the thinned lines, a video signal of the first system in which the lines are thinned, and an output of the character generator. A video signal processing device comprising a synthesizing means for synthesizing. 2. The video signal processing device 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.