JPH0832874A - Four-pattern display device - Google Patents

Abstract

PURPOSE:To provide a four-pattern display device in which the number of frame memories in use is reduced and the cost is reduced. CONSTITUTION:The display device is made up of a line memory 5 writing 1H video data from an input A, a line memory 6 writing 1H video data from an input B, a frame memory 10 interleaving 1H video data read from the line memories 5, 6 at a double speed at an interval of one scanning line and writing the data in a prescribed sequence, a line memory 7 writing 1H video data from an input C, a line memory 8 writing 1H video data from an input D, a frame memory 11 interleaving 1H video data read from the line memories 7, 8 at a double speed at an interval of one scanning line and writing the data in a prescribed sequence, and the data are read from the frame memories 10, 11 alternately for a period being a half of a vertical scanning period and the resulting data are synthesized and outputted.

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,
In particular, the present invention relates to an image display device in which one screen is divided and four screens can be displayed.

[0002]

2. Description of the Related Art A conventional four-screen display device is provided with a frame memory for each video signal input, and controls writing and reading with respect to each frame memory to create a child screen signal and synthesize it to create a single screen signal. It was supposed to be displayed on the screen.

[0003]

Therefore, at least 4
There is a problem that more than two frame memories are required and the cost becomes high. The present invention can reduce the number of frame memories used and reduce the cost.
An object is to provide a screen display device.

[0004]

A four-screen display device according to the first invention of the present application includes a first line memory capable of writing video data of 1H of a first video signal input and reading the video data at a double speed, and a second line memory. A second line memory capable of writing 1H video data of the video signal input and reading at double speed,
The 1H video data read from the first line memory and the 2nd line memory is thinned out every other line, and the first video memory is writable in a predetermined order. A third line memory capable of writing input 1H video data and readable at double speed; and a fourth line memory capable of writing 1H video data of a fourth video signal input and readable at double speed;
It is composed of a second video memory in which 1H video data read out from the third line memory and the fourth line memory is thinned out every other line and writable in a predetermined order. The first for each period
And the second video memory are alternately read out during a half period of the vertical scanning period, synthesized, and output. The four-screen display device of the second invention of the present application is characterized in that the video memory comprises a frame memory or a field memory.

[0005]

According to the present invention, as described above, 1 of each video signal input is used.
By writing H video data to each line memory and doubling the read speed, the horizontal time axis is set to 1
/ 2, 1H video data from each line memory is thinned out every other line, and 2 line memories are grouped together to sequentially write 1H video data to each video memory, writing 1 frame or 1 field. After the end, the size in the vertical direction is compressed by reading in the half of the vertical scanning period, and by writing in the video memory in a predetermined order, two images can be displayed by designating the display position of the horizontal image. By synthesizing and alternately reading from the first video memory and the second video memory every half period of the vertical scanning period, the display position of the image in the vertical direction is specified, and the synthesized image is output. If it is displayed on the display device based on the same output, it is possible to divide one screen into four and display the image of each video signal input.

[0006]

FIG. 1 is a block diagram of a four-screen display device showing an embodiment of the present invention, and FIG. 2 is an explanatory view showing a display example according to the present invention. Refer to FIGS. 1 and 2 below. An example will be described. It is assumed that the video signal inputs A to D respectively input to the input terminals 1 to 4 are synchronized with each other. The 1H video data of the input A input through the input terminal 1 is written to the line memory 5 under the control of the memory control unit 9 and is read out at a double speed of the writing speed to be output. The line memory 6 is provided with the input terminal 2 The input B 1H video data input via the input is input under the control of the memory control unit 9 and is read out at a double speed of the write speed and output. The line memory 7 receives the input C 1H input via the input terminal 3. The video data of is written under the control of the memory control unit 9, and is read out and output at a double speed of the writing speed,
The 1H video data of the input D input through the input terminal 4 is written in the line memory 8 under the control of the memory control unit 9 and is read and output at a double speed of the writing speed to output the input signals A to D. On the other hand, the horizontal time axis can be compressed to 1/2.

The image data of 1H read from the line memory 5 and the line memory 6 is thinned out every other line, and the line memory 6 and the line memory 6 are arranged in a predetermined order.
The 1H video data read from the memory is written into the frame memory 10 for each frame under the control of the memory control unit 12 and is read out after the writing of one frame is completed. As a result, as shown in FIG. B
Image is compressed to 1/2 in the vertical direction, input A is displayed on the left side and input B is displayed on the left side, and input A and input B are specified. It becomes possible to synthesize. Similarly, 1H video data read from the line memory 7 and the line memory 8
The data is thinned out every other line, and in a predetermined order, for example, 1H video data read from the line memory 8 next to the line memory 7 is written in the frame memory 11 for each frame under the control of the memory control unit 12 and after one frame is written It is designed to read in half the vertical scanning period,
As a result, as shown in FIG. 2, the images of the input C and the input D are compressed to 1/2 in the vertical direction, the input position C is displayed on the left side of the horizontal image display position, and the input D is displayed on the right side. It is possible to synthesize the input C and the input D by designating that

Under the control of the memory controller 12, the frame memory 10 and the frame memory 11 are alternately read out every half period of the vertical scanning period, and further combined to output a video signal. Next, by reading from the frame memory 11, for example, as shown in FIG. 2, the display position of the image in the vertical direction is designated so that the input A and the input B are on the upper side and the input C and the input D are on the lower side. It is possible to divide one screen into four and display the image of each video signal input. In the above-mentioned embodiment, an example in which the frame memories 10 and 11 are used as the video memory is shown.
A field memory may be used instead of.

[0009]

As described above, according to the present invention,
By writing 1H video data of each video signal input to each line memory and doubling the read speed, the horizontal time axis is compressed to 1/2, and 1H video data from each line memory is compressed. Vertical size is reduced by thinning out every other line, writing 1H video data in sequence to each frame memory in groups of two line memories, and reading out in half the vertical scanning period after writing one frame. Are compressed and written in a predetermined order when writing to the frame memory, thereby specifying the display position of the image in the horizontal direction to synthesize the two images, and from the two frame memories every half of the vertical scanning period. By alternately reading, specify the display position of the vertical image,
When they are combined and output, and if they are displayed on the display device based on the same output, it is possible to divide one screen into four and display the image of each video signal input. Since the number of devices used is reduced, it is possible to provide a low cost four-screen display device.

[Brief description of drawings]

FIG. 1 is a block diagram of a four-screen display device showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a display example according to the present invention.

[Explanation of symbols]

 1 input terminal 2 input terminal 3 input terminal 4 input terminal 5 line memory 6 line memory 7 line memory 8 line memory 9 memory control unit 10 frame memory 11 frame memory 12 memory control unit

Claims (2)

[Claims] 1. A first line memory capable of writing 1H video data of a first video signal input and read at double speed, and a first line memory writing 1H video data of a second video signal input and read at double speed. A second line memory, and a first video memory in which 1H video data read from the first line memory and the second line memory are thinned out every other line, and writable in a predetermined order. Similarly, 1H video data of the third video signal input can be written and read at double speed, and a third line memory that can read 1H video data of the fourth video signal input and read at double speed. The fourth line memory, and the 1H video data read from the third line memory and the fourth line memory are thinned out every other line and written in a predetermined order. A second video memory that can be plugged into the first video memory and the second video memory.
The four-screen display device is characterized in that it is read from the video memory alternately in half the period of the vertical scanning period, synthesized, and outputted. 2. The four-screen display device according to claim 1, wherein the video memory comprises a frame memory or a field memory.