JPH066723A - Image display device - Google Patents

Abstract

PURPOSE:To improve brightness on the center part of a screen so as to easily observe an image by reducing the scanning speed of scanning lines on the center of the screen and increasing it on both the ends at the time of receiving a high-vision signal. CONSTITUTION:At the time of receiving clock signals from a control part 6, a line memory 2 sets up the frequency ratio between writing and reading clock signals so that the frequency of the reading clock signal is increased several times that of the writing clock signal, compresses the inputted video signal on the right and left ends of the horizontal scanning lines of the video image and outputs the partially compressed signal. On the other hand, a line memory 4 increases the frequency of the writing clock signal several times that of the reading clock signal, extends the inputted video signal on the center part of its horizontal scanning line and outputs the partially extended signal. A multiplier 5 multiplies picture element data read out from the memory 4 by a prescribed coefficient to weight the data and outputs the weighted data to a selector 3, which switches and outputs an input from the multiplier 5 or an input from the memory 2 and the scanning speed of the screen is set up based upon the output from the selector 3 so as to be delayed on the center part of the screen as compared with the horizontal peripheral parts.

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, a horizontal scanning line of a video signal is written. A line memory 2 and a line memory 4 for reading and outputting, a control unit 6 for controlling writing and reading to and from the memories 2 and 4, and pixel data read from the line memory 4 multiplied by a predetermined coefficient and output. Multiplier 5
And a selector 3 for switching and outputting the input from the multiplier 5 and the input from the line memory 2. In the line memory 2, the frequency ratio of the clock signal for writing and the reading is multiplied by several times for reading. Then, the video signals at the left end and the right end of the horizontal scanning line are compressed and output, and in the line memory 4, the frequency ratio of the clock signal for writing and reading is increased several times for writing, and The image signal of the central portion is expanded and output, and based on the both outputs, the scanning speed of the screen is made slower in the central portion than in the peripheral portion in the horizontal direction of the screen for scanning.

[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,
The current of a waveform with a steep rise at both ends of the scanning period and a gentle slope in the central part is passed through the horizontal deflection yoke, so that the scanning speed of the screen is slower in the central part than in the peripheral part in the horizontal direction. It becomes possible to increase the brightness of the central portion of the image receiving screen to make it easier to see when receiving a high-definition 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) which is converted into a digital signal and extracted is input, and the input is branched via the input terminal 1 and input to the line memory 2 and the line memory 4. . The line memories 2 and 4 have a FIFO (first
-in first-out) type video signal input through the input terminal 1 using the write clock signal (Wck) and the read clock signal (Rck) input from the control unit 6. The horizontal scanning lines are written, read in order, and output. In the line memory 2, at the left end and the right end of the horizontal scanning line, the frequency ratio of the write clock signal (Wck) and the read clock signal (Rck) can be increased several times in the read operation to compress and output the video signal. I am trying. In the line memory 4, in the central portion of the horizontal scanning line, the frequency ratio of the writing clock signal (Wck) and the reading clock signal (Rck) is increased several times in writing so that the video signal can be expanded and output. I have to. The multiplier 5 multiplies the pixel data read from the line memory 4 by a predetermined coefficient, weights and outputs the result, and the selector 3 switches between the input from the multiplier 5 and the input from the line memory 2. It is configured to output, and by the control signal input from the control unit 6, at the left end and the right end of the horizontal scanning line,
Switching so that the input from the line memory 2 is output,
At the center of the horizontal scanning line, the input from the multiplier 5 is output, and the output from the selector 3 is used as a video signal output. Based on the output, the scanning speed of the screen is set 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 of the line memory 2 of FIG. Din is pixel data of the input video signal, Wck is a write clock signal for the line memory 2, and Rck is Rck.
Indicates a read clock signal for the line memory 2, and D1out indicates 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 set to 8
The video signal is doubled to compress the video signal to ⅛. For example, for pixel data 1 to 25 or less of Din,
As ut, 1, 9, and 17 or less are output.

FIG. 4 is a timing chart showing the video signal processing of the line memory 4 of FIG. Din is pixel data of the input video signal, Wck is a clock signal for writing to the line memory 4, and Rck is Rck.
Indicates a read clock signal for the line memory 4, and D2out indicates pixel data output from the line memory 4 as a video signal. In the central portion of the horizontal scanning line (the portion shown in B of FIG. 2), when the read clock signal (Rck) 1 is used, the write clock signal (Wck) is increased 8 times and the video signal is extended 8 times. , For example, for Din pixel data # 1 and # 2 or less, D
As 2out, each pixel is read as 8 pixels. When the image signal is processed as described above, in FIG. 2, both ends of the scanning period (portions A and C)
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 FIGS. 3 and 4, the video signals at the left end and the right end (portions shown in A and C of FIG. 2) of the horizontal scanning line are compressed to ⅛, and the center of the horizontal scanning line (in FIG. 2) is compressed. In the part (shown in B), the expansion is performed 8 times, but the numerical values for compression and expansion may be 1/2 and 2 or may be other numerical values.

FIG. 5 is an explanatory diagram concerning multiplication by the multiplier 5 of FIG. Xn is D input from the line memory 4
2out pixel, and as shown in FIG. 4, each pixel # 1
The following are input as 8 pixels each, and Xn and X (n +
For the input of 8), Yn and Y (n + 8) are output, respectively. An intermediate pixel Y (n +) between Yn and Y (n + 8)
a) is a coefficient for one of the input pixels, (8-a) / 8
Are multiplied, and the other is multiplied by a / 8, weighted, added, and output. The calculation formula is as follows. Y (n + a) = Xn · (8−a) / 8 + X (n + 8) · a / 8 where a is an integer, and 1 ≦ a ≦ 7 Therefore, the pixel expanded by the line memory 4 is # 1.
It gradually changes from # 2 to # 2, and the boundary line can be blurred to make it inconspicuous.

[0011]

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.

3 is a timing chart showing video signal processing of the line memory 2 of FIG.

FIG. 4 is a timing chart showing video signal processing of the line memory 4 of FIG.

5 is an explanatory diagram related to multiplication by a multiplier 5 in FIG. 1. FIG.

[Explanation of symbols]

 1 Input Terminal 2 Line Memory 3 Selector 4 Line Memory 5 Multiplier 6 Control Unit

Claims (1)

[Claims] 1. A first line memory and a second line memory for writing, reading and outputting a horizontal scanning line of a video signal, a control unit for controlling writing and reading to and from the memory, and reading from the second line memory. And a selector for switching between the input from the multiplier and the input from the first line memory for output, and the first line memory, The frequency ratio of the clock signals for writing and reading is made several times higher than that for reading, and the video signals at the left end and the right end of the horizontal scanning line are compressed and output. In the second line memory, the write and read clock signals are output. The frequency ratio of the writing is made several times higher than that of writing, and the video signal at the center of the horizontal scanning line is expanded and output. An image display device, characterized in that scanning is performed with the central portion being slower than the peripheral portion in the direction.