JPH066724A - Image display device - Google Patents

Abstract

PURPOSE:To reduce a scanning speed and to improve the brightness of an image receiving screen so as to easily observe an image by simultaneously scanning the right and left halves of the screen by respective electron guns for an 1H period by means of a CRT having two electron guns. CONSTITUTION:An image signal input obtained by extracting a converted digital signal is delayed by the 1/2H period of a horizontal scanning period through a delay circuit 2 and inputted to a line memory 3 and writing and reading clock signals supplied from a control part 5 are set up to prescribed timing. Thereby a line memory 3 reads out and outputs a left half of the horizontal scanning lines of the video signal and a line memory 4 reads out and outputs a right half of the horizontal scanning lines, respective image signals outputted from both the memories 3, 4 are inputted to respective electron guns included in the CRT and the right and left halves of the screen are simultaneously scanned for the 1H period of the horizontal scanning period to reduce the scanning speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display device using a CRT.

[0002]

2. Description of the Related Art High-definition images have lower brightness than ordinary televisions currently in use. One of the reasons is that the scanning speed of high-definition scanning lines is different from that of ordinary televisions. It is due to being faster.

[0003]

SUMMARY OF THE INVENTION The present invention uses a CRT having two electron guns so that each electron gun simultaneously scans the left and right halves of the screen during a horizontal scanning period of 1H. Then, unlike the conventional method that scans from the left edge to the right edge of the screen with one electron gun, the scanning speed is slowed down and the brightness of the image receiving screen is raised to make it easier to see when receiving an HDTV signal. And

[0004]

FIG. 1 is a block diagram of an electric circuit of an essential part of an image display device showing an embodiment of the present invention. As shown in FIG. 1, it is converted into a digital signal and extracted. 1 / 2H of horizontal scanning period for video signal input
Delay circuit 2 which delays and outputs the delay time, and line memory 3 which writes, reads and outputs the input from the delay circuit 2.
A line memory 4 for writing, reading and outputting the video signal input, and a control unit 5 for supplying a clock signal for writing and reading to the line memories 3 and 4, and writing and reading by the line memory 3. By setting the clock signal for the specified timing,
About the left half of the horizontal scanning line of the video signal is read and output,
The line memory 4 reads and outputs about the right half of the horizontal scanning line of the video signal by setting the write and read clock signals at predetermined timings, and the CRT having two electron guns based on both outputs. A video signal is input to each electron gun, and the left half and the right half of the screen are simultaneously scanned.

[0005]

As described above, according to the present invention, the horizontal scanning line of the video signal is written to the line memory and the timing of the clock signal to be read is controlled, so that in the line memory 3, about the left side of the horizontal scanning line of the video signal. Half of the horizontal scanning lines of the video signal are read out and output in the line memory 4, and the video signal is input to each electron gun of the CRT having two electron guns based on the same output. Then, unlike the conventional method in which the left half and the right half of the screen are simultaneously scanned during the 1H period of the horizontal scanning period to scan from the left end to the right end of the screen with one electron gun, the screen is scanned. It becomes possible to scan at a slower speed, and at the time of receiving an image of a high-definition signal, it becomes possible to raise the brightness of the image receiving screen to make it easier to see.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram of an essential electric circuit of an image display device showing an embodiment of the present invention. Reference numeral 1 denotes an input terminal to which a video signal (Din) which is converted into a digital signal and extracted is input. The input is branched via the input terminal 1 and input to the delay circuit 2 and the line memory 4. Therefore, the delay circuit 2 delays the video signal input by 1 / 2H of the horizontal scanning period and outputs the delayed video signal, which is input to the line memory 3. The line memories 3 and 4 have a FIF.
The O (first-in first-out) type is used, and the horizontal scanning of the input video signal is performed by using the write clock signal (Wck) and the read clock signal (Rck) input from the control unit 5. The lines are written, read in order, and output.

FIG. 2 is an explanatory diagram relating to signal processing of image data according to the present invention. Din is pixel data of the input video signal, D1out is pixel data output from the line memory 3 as a video signal, and D2
out is pixel data output from the line memory 4 as a video signal. When a MUSE system signal is used as the high-definition signal, each line of the horizontal scanning lines of the video signal is sampled at 480 points in the MUSE system, and the pixel data of the input video signal is shown as Din. As described above, the pixel data of 1 to 480 are arranged.

In the line memory 3, by setting the write and read clock signals at a predetermined timing,
About the left half of the horizontal scanning line of the video signal input Din, 1 to 24
The pixel data up to 0 is read out and output as D1out, and the video signal input to the line memory 3 is delayed by 1 / 2H of the horizontal scanning period by the delay circuit 2. Therefore, for Din, The signal is delayed by 1 / 2H. By setting the write and read clock signals at a predetermined timing in the line memory 4,
About the right half of the horizontal scanning line of the video signal input Din, 241-
Pixel data up to 480 is read out and output as D2out, so 1/2 for Din
The signal is delayed by H.

FIG. 3 is an explanatory view showing a screen deflection state according to the present invention. A CRT having two electron guns for forming three beams is used, and the video signal output, D1out, from the line memory 3 of FIG.
The video signal output from the line memory 4 in FIG.
ut is input, the electron gun 1 scans the left half of the screen, pixel data 1 to 240 for 1H of the horizontal scanning period, and the electron gun 2 scans the right half of the screen, pixel data 2
41H to 480 are scanned at the same time as the electron gun 1 by taking 1H period of the horizontal scanning period. Therefore, unlike the conventional method that scans from the left side to the right side of the screen with one electron gun, it becomes possible to scan at a slower screen speed, and when receiving a high-definition signal,
The brightness of the image receiving screen can be increased to make it easier to see.

[0010]

As described above, according to the present invention,
By writing the horizontal scanning line of the video signal to the line memory and controlling the timing of the clock signal to be read,
The line memory 3 reads and outputs about the left half of the horizontal scanning line of the video signal, and the line memory 4 reads and outputs about the right half of the horizontal scanning line of the video signal, and outputs two electronic signals based on both outputs. By inputting a video signal to each electron gun of a CRT having a gun and scanning the left half and the right half of the screen at the same time, the scanning speed of the screen can be made slower than the conventional scanning. The brightness can be increased to make it easier to see, and if the present invention is applied to an image display device for high-definition signals, it greatly contributes to improvement in the performance of the image display device.

[Brief description of drawings]

FIG. 1 is a block diagram of an essential electric circuit of an image display device, showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram related to signal processing of image data according to the present invention.

FIG. 3 is an explanatory diagram showing a screen deflection state according to the present invention.

[Explanation of symbols]

 1 Input Terminal 2 Delay Circuit 3 Line Memory 4 Line Memory 5 Controller

Claims (1)

[Claims] 1. A delay circuit for delaying and outputting for 1 / 2H of a horizontal scanning period to a video signal input converted into a digital signal and outputting, and writing, reading and outputting the input from the delay circuit. The first line memory includes a second line memory that writes, reads and outputs the video signal input, and a controller that supplies write and read clock signals to the first and second line memories. The line memory reads out and outputs about the left half of the horizontal scanning line of the video signal by setting the write and read clock signals at predetermined timings, and the second line memory sets the write and read clock signals at predetermined times. The right half of the horizontal scanning line of the video signal is read out and output by the timing of, and two electron guns are output based on both outputs. An image display device characterized by inputting a video signal to each electron gun of a CRT and scanning the left half and the right half of the screen at the same time.