JPH066722A - Image display device - Google Patents

Abstract

PURPOSE:To improve brightness on the center part of a screen so as to easily observe an image on the screen by reducing the scanning speed of scanning lines on the center of the screen and increasing it on both the ends to receive a high-vision signal. CONSTITUTION:When an image signal converted into a digital signal and extracted is inputted, a writing clock signal (Wck) and a reading clock signal (Rck) are inputted from a control part 3 for controlling a line memory 2 for storing the horizontal scanning lines of a video signal to the line memory 2. On the left and right ends of the horizontal scanning lines, the frequency of reading clock signal is increased several times the frequency of the writing clock signal and the video signal is compressed and outputted from a video signal output 4, and on the center of the horizontal scanning lines, the frequency of the writing clock signal is increased several times that of the reading clock signal and the video signal is extended and outputted. Thus the scanning speed of the screen is delayed on the center part of the screen as compared with the horizontal peripheral part.

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 According to the present invention, the scanning speed of scanning lines is slowed down at the center of the screen and fastened at both ends to receive a high-definition signal, thereby increasing the brightness of the central portion of the screen for easy viewing. The purpose is to do.

[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, horizontal scanning lines of video signals are stored. The line memory 2 and the control unit 3 for controlling the line memory 2 are used to input a write clock signal (Wck) and a read clock signal (Wck) from the control unit 3 with respect to the video signal input that is converted into a digital signal and extracted. Rck) is input to the line memory 2, and at the left end and the right end of the horizontal scanning line, the frequency ratio of the clock signal for writing and reading is increased several times in reading and the video signal is compressed and output. At the center of the scanning line, the frequency ratio of the clock signal for writing and reading is made several times higher than that for writing and the video signal is expanded and output, and the scanning speed of the screen is based on both outputs and the horizontal direction of the screen. It is to slow to scan the central portion than the peripheral portion.

[0005]

According to the present invention, the video signal is compressed at the left end and the right end of the horizontal scanning line and the video signal is expanded at the center of the horizontal scanning line according to the above configuration. FIG. 6 is an explanatory view showing a deflected state, and as shown in the figure, the period of 1H of the horizontal scanning line is not changed,
A current having a waveform with a steep rise at both ends (portions A and C) of the scanning period and a gently sloping waveform at the central portion (portion B) is passed through the horizontal deflection yoke, so that the scanning speed of the screen becomes horizontal. It becomes possible to scan the central part later than the peripheral part in the direction, and it becomes possible to raise the brightness of the central part of the image receiving screen to make it easier to see when receiving an HDTV signal.

[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) converted into a digital signal and extracted is input, and the input is input to the line memory 2 via the input terminal 1. A FIFO (first-in first-out) type memory is used as the line memory 2, and a write clock signal (Wck) and a read clock signal (Rck) input from the control unit 3 are used to input terminals. The horizontal scanning lines of the video signal input via 1 are written, read in order, and output. At the left and right ends of the horizontal scanning line, a write clock signal (Wck) and a read clock signal (Rc
The video signal is compressed by increasing the frequency ratio of k) to several times higher than that of the reading, and the writing clock signal (Wck) and the reading clock signal (Rck) are provided at the center of the horizontal scanning line.
The frequency ratio of writing is made several times higher than that of writing, and the video signal is expanded and output as a video signal output (Dout) through the output terminal 4, and based on the output, the scanning speed of the screen is increased in the horizontal direction of the screen. The central part is slower than the central part so that scanning can be performed.

FIG. 2 is an explanatory view showing the deflection state of the screen according to the present invention. As shown in FIG.
The period of time is kept unchanged, and a steep rise is made at both ends (portions A and C) of the scanning period, and a current having a waveform with a gentle slope is fed to the horizontal deflection yoke at the central portion (portion B), Scanning speed of the screen can be made slower in the central part than in the peripheral part in the horizontal direction of the screen, and the brightness of the central part of the screen can be increased by scanning and displaying the video signal processed in FIG. I am trying.

FIG. 3 is a timing chart showing the video signal processing according to the present invention. Din is pixel data of the input video signal, Wck indicates a write clock signal for the line memory 2, Rck indicates a read clock signal for the line memory 2, and Dou
t represents pixel data output from the line memory 2 as a video signal. When the frequency of the write clock signal (Wck) is set to 1 at the left end and the right end (portions shown in A and C of FIG. 2) of the horizontal scanning line, for example, the frequency of the read clock signal (Rck) is increased eight times. Then, the video signal is compressed to ⅛, and when the read clock signal (Rck) 1 is set at the center of the horizontal scanning line (the portion indicated by B in FIG. 2), the write clock signal (W
ck) is increased eight times to expand the video signal eight times so that the video signal output (Dout) can be output from the line memory 2.

When the video signal is processed as described above, both ends of the scanning period (portions A and C) in FIG.
Then, the screen is scanned at a scanning speed that is 8 times the normal scanning speed, and the screen is scanned at the scanning speed that is 1/8 the normal scanning speed in the central portion (B portion), so that the entire 1H scanning period does not change. To scan. In the embodiment shown in FIG. 3, the video signals at the left end and the right end of the horizontal scanning line are compressed to 1/8,
At the center of the horizontal scanning line (portion shown in B of FIG. 2), the expansion is performed 8 times, but the compression and expansion value is 1.
/ 2 and double may be used, or another value may be used.

[0010]

As described above, according to the present invention, the video signal is compressed at the left end and the right end of the horizontal scanning line and the video signal is expanded at the center of the horizontal scanning line. Based on the video signal, the scanning speed of the screen is slower in the central part than in the peripheral part of the screen in the horizontal direction to scan, so that it is possible to increase the brightness of the central part of the screen to make it easier to see. If the present invention is applied to an image display device, it greatly contributes to improving 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 showing a screen deflection state according to the present invention.

FIG. 3 is a timing chart showing video signal processing according to the present invention.

[Explanation of symbols]

 1 input terminal 2 memory 3 control unit 4 output terminal

Claims (1)

[Claims] 1. A clock for writing and reading at a left end and a right end of a horizontal scanning line with respect to a video signal input which is converted into a digital signal and extracted by using a line memory circuit for storing the horizontal scanning line of the video signal. The video signal is compressed and output by increasing the frequency ratio of the signal to several times higher than that of the read image. At the center of the horizontal scanning line, the frequency ratio of the clock signal for writing and reading is increased to several times higher than that of the writing image. An image display device characterized in that a signal is expanded and outputted, and based on the both outputs, the scanning speed of the screen is made slower in the central part than in the peripheral part in the horizontal direction of the screen for scanning.