JP2000184315A - Display unit and multi-screen display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance image quality of a displayed video image and to simplify the adjustment for each display unit. SOLUTION: A selector 15 selects a digital video signal b1 from an A/D converter 11 or a digital video signal c1 from an input interface means and leads the selected signal to a magnifieation processing circuit 13 and an output interface means 17. The magnification processing circuit 13 applies magnification processing to a preset partial video image of a digital video signal and allows a screen display means 14 to display it. The output interface means 17 outputs the digital video signal from the selector circuit i5 externally via an output terminal 25.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display unit capable of enlarging an image signal and displaying the image signal on a screen, and a multi-screen display capable of forming a multi-screen by combining a plurality of display units. Related to the device.

[0002]

2. Description of the Related Art In recent years, a multi-screen display device in which a plurality of display units are combined to form one large screen has become widespread. In a display unit used in such a conventional multi-screen display device,
As a screen display means, a CRT and a projection display device based on the CRT are widely used. Such a multi-screen display device is frequently used in presentations at exhibitions, concerts, television studios, and the like.

Further, in such a multi-screen display device, one large screen is formed by supplying a plurality of display units with video signals that have been subjected to enlargement processing by an enlargement processing circuit in advance. Some display units have an enlargement processing function.

FIG. 3 is a block diagram showing a conventional display unit having an enlargement processing function.

[0005] In FIG. 3, a display unit 6 includes an analog / digital converter (hereinafter, referred to as an AD converter) 61, a phase locked loop synchronization generation circuit (hereinafter, referred to as a PLL synchronization generation circuit) 62, and an enlargement processing circuit 63. And a screen display unit 64.

The display unit 6 has input terminals 71, 72
The input terminal 71 guides an RGB analog video signal, and the input terminal 72 guides horizontal and vertical synchronization signals.

The RGB analog video signal guided to the input terminal 71 is supplied to the AD converter 61,
2 are supplied to the PLL synchronization generation circuit 62. The PLL synchronization generation circuit 62 generates a sampling clock a2 in synchronization with the frequency of the supplied horizontal and vertical synchronization signals.

[0008] The AD converter 61 receives RGB signals.
Is sampled at the timing of the rising edge of the sampling clock a2, and an RGB digital video signal b2 is created and supplied to the enlargement processing circuit 63. The enlargement processing circuit 63 enlarges the RGB digital video signal b2 and supplies it to the screen display means 64 to display the enlarged video.

FIG. 4 is a block diagram showing a multi-screen display device using a plurality of display units shown in FIG.

In FIG. 4, display units 6-1 and 6-
2, 6-3 and 6-4 have the same configuration as the display unit 6 shown in FIG.

The RGB analog video signal and the horizontal and vertical synchronizing signals guided to the input terminal 81 are distributed by the distributor 82 and supplied to the display units 6-1, 6-2, 6-3, 6-4. You. Display units 6-1, 6-2, 6-3, 6
-4, after converting the supplied RGB analog video signals into digital video signals, the respective enlargement processing circuits 6
3. Enlarge and display on the screen. For example, one image is divided and supplied to each of the display units (6-1 to 6-4) and enlarged and displayed, whereby a large-screen image can be displayed as a whole.

In such a conventional multi-screen display device, since only the display units and the distributor are required to be installed, the installation work becomes easy.

In recent years, with the spread of personal computers (hereinafter, referred to as PCs), opportunities for using personal computers as video sources of multi-screen display devices have been increasing. The analog video signal output from the PC has a much higher bandwidth than a conventional video source. For example, a signal commonly called “XGA” has a band of 30 MHz or more, and the sampling clock in the AD converter 61 in FIG. 3 requires 65 MHz or more. Further, the sampling clock in this case needs to be accurately reproduced by the PLL synchronization generating circuit in both its frequency and phase.

FIG. 5 shows the analog video signal of the PC in FIG.
FIG. 5A is a waveform diagram showing a case where AD conversion is performed by the D converter 61. FIG. 5A shows an analog video signal of a PC.
(B) shows the sampling clock a2.

FIG. 5A shows an eye pattern of the PC. In the PLL synchronization generating circuit 62, FIG.
Is reproduced. If the frequency or phase of the sampling clock a2 is shifted, sampling will be performed at the changing point of the analog video signal.
On the screen of the display device, fine vertical lines appear to be unstable or blurred.

Although it is inevitable that the clock reproduced by the PLL synchronization generation circuit 62 has some jitter, the clock cycle is 15 ns or less, so that very high precision is required.

Under these circumstances, in the conventional multi-screen display device, since the analog video signal is distributed by the distributor 82, the distortion and dullness of the analog video signal supplied to each display unit increase, and The image quality of the image displayed on the screen was degraded. Further, it is difficult for each display unit to reproduce the sampling clock with high accuracy due to the waveform distortion of the synchronizing signal and variations in the group delay in the distributor 82. The image quality of the digital video signal deteriorates, and the image quality of the image displayed on the screen is reduced. Further, the PLL synchronization generation circuit 62
Must be readjusted for each display unit, and if the number of clocks is large, it takes much time.

[0018]

In the conventional multi-screen display device described above, since the analog video signal is distributed by the distributor, the distortion and dullness of the analog video signal supplied to each display unit are increased, and the screen display is performed. The image quality of the video was degraded. In addition, it is difficult for each display unit to reproduce the sampling clock with high accuracy due to the waveform distortion of the synchronization signal and the group delay variation in the distributor.
When displaying the C analog video signal, the image quality of the digital video signal AD-converted by the AD converter is deteriorated, and the image quality of the screen display video is reduced. Furthermore, P
The phase of the clock reproduced by the LL synchronization generation circuit must be readjusted for each display unit.

It is an object of the present invention to provide a display unit and a multi-screen display device which can eliminate the above-mentioned problems, improve the image quality of a display image, and simplify the adjustment operation for each display unit.

[0020]

According to a first aspect of the present invention, a display unit includes a first input terminal to which an analog video signal is supplied, and an analog video signal supplied to the first input terminal. Analog-to-digital conversion means for converting and outputting a digital video signal; a second input terminal to which an external digital video signal is supplied;
A selector circuit for selectively outputting the digital video signal from the digital conversion means and the digital video signal supplied to the second input terminal, and an output for outputting the digital video signal selected by the selector circuit to the outside A terminal, signal processing means capable of enlarging and outputting the digital video signal selected by the selector circuit, and screen display means for displaying the video signal output from the signal processing means on a screen. It is characterized by the following.

According to a second aspect of the present invention, there is provided a multi-screen display device including a plurality of display units having the above-described configuration, and when displaying one image on the entire multi-screen, the plurality of display units are connected in a cascade. At the same time, an analog video signal is supplied to the first input terminal of the first-stage display unit, and the video signal converted into a digital signal by the first-stage display unit is output from the output terminal via a selector circuit. The display unit after the stage supplies a signal from the output terminal of the preceding stage display unit to the second input terminal, and the digital video signal supplied to the second input terminal is supplied to the output terminal via the selector circuit. So that the video signals selected by the selector circuits of the plurality of display units are enlarged and displayed on the screen display means. It is characterized in that the.

[0022]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing one display unit constituting the multi-screen display device of the present invention.

In FIG. 1, a display unit 1 includes an analog / digital converter (hereinafter, referred to as an AD converter) 11, a phase locked loop synchronization generation circuit (hereinafter, referred to as a PLL synchronization generation circuit) 12, and an enlargement processing circuit 13. , Screen display means 14, selector circuit 15, input interface means 16, and output interface means 17.

The display unit 1 has an input terminal 2
1, 22, 23 and 24 are provided, and an input terminal 21 is provided.
The RGB analog video signal is guided to the input terminal 22.
Horizontal and vertical synchronizing signals are guided to the input terminal 23, an external digital video signal is guided to the input terminal 23, and the input terminal 24
Is supplied with a selection control signal.

The RGB analog video signal guided to the input terminal 21 is supplied to the AD converter 11,
2 are supplied to the PLL synchronization generation circuit 12. The PLL synchronization generation circuit 12 generates a sampling clock a1 at a frequency synchronized with the supplied horizontal and vertical synchronization signals.

The AD converter 11 receives the supplied RGB
Is sampled at the rising edge of the sampling clock a1.
A digital video signal b1 of B is created and guided to a first input terminal of the selector 15. With such a configuration, the AD converter 11 and the PLL synchronization generation circuit 12 are analog / digital conversion means for converting an analog video signal into a digital video signal.

The input interface means 16 inputs the digital video signal from the input terminal 23 and
5 to guide the digital video signal c1 to the second input terminal.

The selector 15 selects one of the digital video signal b1 from the AD converter 11 and the digital video signal c1 from the input interface unit 16 based on the selection control signal from the input terminal 24, and And output interface means 17.

The enlargement processing circuit 13 can enlarge the digital video signal from the selector 15,
The enlarged image is displayed on the screen display unit 14.

The output interface means 17 serves to output the digital video signal output from the selector circuit 15 to the outside via the output terminal 25.

The input interface means 16 and the output interface means 17 use, for example, the "TMDS" method or the "LVDS" method.

FIG. 2 is a block diagram showing a multi-screen display device 30 constituted by using a plurality of display units of FIG.

In FIG. 2, each display unit 1-1, 1
-2, 1-3 and 1-4 have the same configuration as that of FIG. Since the display units 1-3 and 1-4 are in the same connection state as the display units 112, only simple blocks are shown.

Each of the display units 1-1 to 1-4 is cascaded in multiple stages, and an analog video signal is supplied only to the first-stage display unit 1-1. In the first-stage display unit 11, the input analog video signal is converted into a digital video signal by the DA converter 11, and this digital video signal is supplied to the next-stage display unit 1-2. 1-3, 1-4
Are supplied with digital video signals from the display units 1-2 and 1-3 at the preceding stage.

This state will be described in detail. An RGB analog video signal is supplied to the input terminal 21 of the first-stage display unit 1-1, and horizontal and vertical synchronizing signals are supplied to the input terminal 22. Is converted into a digital video signal by the AD converter 11 and the PLL synchronization generation circuit 12. The converted digital video signal is selected by the selector 15 and supplied to the enlargement processing circuit 13 and the output interface means 17. The input terminal 24 of the display unit 1-1 has an AD converter 1
The selection control signal S1 for selecting the output from the control signal S1 is supplied.

On the other hand, the display units 1-2, 1
-3, 1-4 input terminals 23 are connected to the output terminal 25 of the preceding unit, and the display units 1-1, 1-1-
Digital video signals from the display units 2 and 1-3 are supplied to the input interface means 16 of the next-stage display units 1-2, 1-3 and 1-4. Also, the display units 1-2, 1-
A selection control signal S2 for selecting an output from the input interface means 16 is provided to the input terminals 24 of 3, 3 and 4.
Is supplied.

In this way, the digital video signal from the previous stage is guided to the second and subsequent display units, and as a result, the digital video signal that has been AD-converted by the first display unit 1-1 is converted to the other display units. 1-2, 1-3, 1
-4. Further, the video signal enlarged by the enlargement processing circuit 13 at each stage is supplied to the screen display means 14 so that the enlarged image can be displayed.

The video signal supplied to the first-stage display unit 1-1 is converted into a digital signal and then supplied to each of the display units 1-2, 1-3 and 1-4.
In each of the display units 1-1, 1-2, 1-3, and 1-4, a predetermined arbitrary video portion of the input digital video signal is subjected to enlargement processing, so that a large-screen video is displayed as a whole. Can be displayed.

The display units 1-1, 1-2, 1-
3 and 1-4 are supplied with separate analog video signals and synchronizing signals, respectively.
If the digital video signal is selected from the A / D converter 11, the individual video can be displayed on each display unit.

According to the embodiment of the invention shown in FIGS. 1 and 2, when displaying an enlarged large-screen video, an analog video signal is converted to a digital video by a first display unit among a plurality of display units. The digital video signal is converted into a signal, and the digital video signal is enlarged and processed by all other display units to display the video, so there is no need to distribute the analog video signal.
In display units other than the first display unit, it is not necessary to perform AD conversion, and high image quality can be achieved. In addition, the adjustment operation for each display unit can be simplified, thereby simplifying the installation work.

In the embodiment of the invention shown in FIG. 2, a multi-screen display device is constituted by using four display units. However, the present invention can be applied to various types such as nine display units.

[0043]

According to the present invention, the image quality of the displayed image can be improved, and the adjustment operation for each display unit can be simplified, whereby the installation work can be simplified.

[Brief description of the drawings]

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

FIG. 2 is a block diagram of a multi-screen display device using a plurality of display units of FIG.

FIG. 3 is a block diagram showing a conventional display unit.

FIG. 4 is a block diagram showing a multi-screen display device using a plurality of display units of FIG. 3;

FIG. 5 is a waveform chart showing an operation when converting an analog video signal into a digital signal.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Display unit 11 AD converter 12 PLL synchronization generation circuit 13 Enlargement processing circuit 14 Screen display means 15 Selector circuit 16 Input interface means 17 Output interface means

Claims (3)

[Claims] A first input terminal to which an analog video signal is supplied; an analog / digital conversion means for converting the analog video signal supplied to the first input terminal into a digital video signal and outputting the digital video signal; A second input terminal to which a digital video signal is supplied from the second input terminal; a selector for selectively outputting a digital video signal from the analog / digital conversion means and a digital video signal supplied to the second input terminal A circuit, an output terminal for outputting the digital video signal selected by the selector circuit to the outside, a signal processing unit capable of enlarging and outputting the digital video signal selected by the selector circuit, and A display unit for displaying an output video signal on a screen. 2. A display device for forming a multi-screen by combining a plurality of display units, wherein each of the plurality of display units has a first input terminal to which an analog video signal is supplied; Analog-to-digital conversion means for converting an analog video signal supplied to an input terminal of the digital video signal into a digital video signal and outputting the digital video signal; a second input terminal to which an external digital video signal is supplied; A selector circuit for selectively outputting the digital video signal supplied from the second input terminal and the digital video signal supplied to the second input terminal; an output terminal for outputting the digital video signal selected by the selector circuit to the outside; Signal processing means capable of enlarging and outputting the digital video signal selected by the selector circuit; And a screen display means for displaying the video signal output from the management unit to the screen, when displaying one image on entire multi-screen, with cascading the plurality of display units,
An analog video signal is supplied to a first input terminal of a first-stage display unit, and a video signal converted into a digital signal by the first-stage display unit is output from the output terminal via a selector circuit, and the next and subsequent displays are displayed. The unit supplies a signal from an output terminal of a preceding display unit to the second input terminal, and supplies a digital video signal supplied to the second input terminal to the output terminal via a selector circuit. A multi-screen display device, wherein the video signals selected by the selector circuits of the plurality of display units are enlarged and displayed on the screen display means. 3. An input interface means for guiding a digital video signal supplied to a second input terminal of the display unit to the selector circuit, and an input interface means for guiding a digital video signal from the selector circuit to the output terminal. The display unit and the multi-screen display device according to claim 1 or 2, further comprising an output interface means.