JP3344173B2 - Multi-panel display - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-panel display device capable of realizing a large screen by using a plurality of display panels such as a plasma display panel (PDP) and a liquid crystal display panel (LCD panel).

[0002]

2. Description of the Related Art In recent years, researches and developments using a plasma display panel or a liquid crystal display panel as a thin and space-saving display device have been made. In such a panel-type display device, due to manufacturing difficulties, etc.,
There are some restrictions on the size of one panel. Therefore, a plurality of display panels may be used to display a large screen in a public place or the like.

For example, FIG. 6 shows an example in which four plasma display panels are used to realize a four times larger screen. For example, in addition to displaying four types of images by displaying differently on each of the four panels, a method of displaying one image using four panels has been attempted.

[0006] That is, FIG. 6 shows a panel 1-4 each having a frame 5. For example, the character “F” is displayed on four panels 1-4.

On the other hand, the plasma display panel and the liquid crystal display panel have a linear display characteristic unlike a television receiver using a CRT, and therefore have a predetermined characteristic for a CRT added to a video signal at a broadcast station or the like. It is known to add a so-called “γ correction” in order to remove from the video signal.
Further, for the purpose of improving the contrast to compensate for the lack of display gradation, the average brightness (APL: Average Picture Level) of the video of one field.
It is also known to perform “dynamic γ correction” that dynamically switches the characteristic curve of the “γ correction” according to (1, average video level).

The above curve of “dynamic γ correction” is
It is shown in FIG. The horizontal axis indicates the input level according to the display intensity (brightness) supplied to the display device, and the vertical axis indicates the brightness output actually displayed by the display device. Although four correction curves 11-14 are displayed in the figure,
The number of correction curves according to the gray level of the average video level (APL) is used. According to the “dynamic γ correction”, the average brightness of the character 6 portion and the pack ground 7 portion of each panel is calculated, and when the overall brightness is dark, for example, the correction curve 11 is used. When the overall brightness is bright, for example, the correction curve 14 is used. That is, if the entire screen is dark, the brightness of the display screen is increased at a smaller input level, while if the entire screen is bright, the degree of increase in the brightness of the display screen at a larger input level is increased. The correction is made as follows. By doing so, even with an input level of a small number of gradations, an output of an apparently large gradation can be obtained, and the effect of increasing the apparent contrast can be obtained.

FIG. 8 is a schematic diagram of a conventional display processing circuit for performing such “dynamic γ correction”. Signal processing circuits 10, 20, 30, and 40 for supplying display signals to the four display panels 1-4 are provided. Then, a composite signal (CV) 15 is input to each of the signal processing circuits 10-40 as an input signal. Composite signal 1 input to each
5 includes a video signal to be displayed on each display panel and horizontal and vertical synchronization signals.

The input composite signal 15 is separated into an analog RGB signal 17 by an analog processing circuit 16, sampled by a digital signal processing circuit 18, and the sampled value is converted into a digital signal.
As a result, each of the 8-bit RGB digital signals 1
9 is output. This digital RGB signal 19 is input to a look-up table (LUT) 22 and also to an APL detection circuit 20 for detecting an average video level (APL). The APL detection circuit calculates the average value of the brightness of one field of the screen from the RGB digital signal according to a predetermined calculation formula. The APL value thus obtained is used as the γ correction curve selection signal generation circuit 2
In step 1, the signal is encoded into, for example, 32 gradations, and the 5-bit signal is input to the lookup table 22 as a gamma correction curve selection signal.

In the look-up table 22, the digital RGB signal 19 and the .gamma.
Is supplied to the display panel as a display panel video signal. Signal processing circuit 10-
40 has the same configuration.

[0010]

As described above, in the conventional multi-panel display device, the signal processing units for supplying the image signals to the respective display panels individually perform the dynamic gamma correction. Therefore, for example, when the character “F” as shown in FIG. 1 is to be displayed on four display panels, the panel 4 having the largest background is the brightest and the average image level (APL) is the highest, and as a result, 14, 14 curves are selected as the dynamic γ correction curve in FIG.
On the other hand, the correction curve 11 is removed from the darkest panel 1, the correction curve 12 is selected from the second darkest panel 3, and the correction curve 13 is selected from the third darkest panel 2. become. As a result, the correction curves of the four display panels are different from each other for one input level, and the output variation between the darkest panel 1 and the brightest panel 4 becomes extremely large. There was a problem.

For this reason, there is a problem that, when one image is to be enlarged and displayed on a plurality of display panels, the display output differs for each display panel, resulting in an image having variations.

Accordingly, an object of the present invention is to provide a multi-panel display device in which the above-mentioned display output does not vary.

Further, the present invention is directed to a display device using a plurality of display panels for performing dynamic gamma correction, wherein the same dynamic gamma correction is applied to each display panel when one image is to be enlarged and displayed by a plurality of panels. It is an object of the present invention to provide a multi-panel display device capable of supplying a converted video signal.

[0014]

The object of the present invention is to provide a plurality of display panels which are provided adjacent to each other and display an image, and a plurality of display panels which input video signals and supply each display panel with a video signal for each display panel. A video signal processing circuit, and when displaying an enlarged video on a plurality of display panels, each video supplied from a plurality of video signal processing circuits corresponding to the plurality of display panels used for the enlarged display Control means for selecting the same gamma correction curve based on a brightness signal corresponding to the brightness of the plurality of video signal processing circuits and supplying the same selection signal to the plurality of video signal processing circuits; Thus, a multi-panel display device (first invention) is characterized in that a video signal is corrected according to the same γ correction curve.

Further, an object of the present invention is that, in the first invention, one of the plurality of video signal processing circuits corresponding to the plurality of display panels used for the enlarged display is a master video signal processing circuit. Having the control means as a circuit,
Another video signal processing circuit among the plurality of video signal processing circuits supplies a brightness signal to a master circuit as a slave circuit, and inputs the same selection signal to correct the video signal according to the same γ correction curve. This is achieved by a multi-panel display device (second invention) characterized by being added.

[0016] It is another object of the present invention in the first or second invention, wherein the plurality of video signal processing circuits are configured to generate γ based on a brightness signal corresponding to the brightness of the video of the corresponding display panel. When an internal selection signal for selecting a correction curve is generated and an image is displayed on a single panel, a correction based on a predetermined γ correction curve is performed according to the internal selection signal, and when displaying an image on a plurality of display panels, The present invention is attained by providing a multi-panel display device (third invention) in which correction is performed using a predetermined γ correction curve according to the same selection signal.

It is still another object of the present invention to provide the third aspect of the present invention, wherein the internal selection signal is RG separated and extracted from the video signal.
The Y signal for each pixel is calculated from the B signal, the Y signal for one screen is integrated, the integrated value is converted into a predetermined gray level, and the signal having the predetermined gray level is used as an internal selection signal. This is achieved by a multi-panel display device (fourth invention).

According to a fourth aspect of the present invention, in the fourth aspect, the plurality of video signal processing circuits supply an internal selection signal to the control unit as the brightness signal, and the control unit supplies the internal selection signal to the control unit. A multi-panel display device, comprising: calculating an average of signal gray levels among the plurality of panels; and supplying a signal including the average gray levels as a same selection signal to a plurality of video signal processing circuits (fifth invention) ).

[0019] It is still another object of the present invention in the fifth invention, wherein the plurality of video signal processing circuits are adapted to display the internal selection signal and the same selection signal on the single display panel when displaying the video and on the plurality of display panels. A gamma correction curve switching circuit that switches between when the gamma correction curve is displayed, a gamma correction curve selection signal and a video signal output from the gamma correction curve switching circuit, and the gamma correction after the gamma correction according to a look-up table created in advance. This is achieved by a multi-panel display device (sixth invention) having a video signal conversion circuit for outputting a video signal for a display panel.

According to a sixth aspect of the present invention, in the sixth aspect, the gamma correction curve switching circuit includes a first flip-flop for loading the internal selection signal with a first load signal synchronized with a vertical synchronization signal. The circuit and the first flip
A selector circuit for switching between the output signal of the flop circuit and the same selection signal, and loading the output signal of the selector circuit with a second load signal delayed by a predetermined time from the first load signal, and outputting a γ correction curve selection signal And a second flip-flop circuit that performs the operation of the multi-panel display device (seventh invention).

According to a seventh aspect of the present invention, in the seventh aspect, the output signal of the first flip-flop circuit is read by the control means in accordance with a read timing signal supplied at a predetermined timing from the control means. This is achieved by a multi-panel display device (eighth invention).

According to the present invention, even when the display is enlarged on a plurality of display panels, the video signals for the plurality of cover panels are corrected according to the same γ correction curve.
Variations in brightness between display panels can be eliminated.

The above-mentioned brightness signal is a signal indicating the average brightness of one field. For example, a predetermined number of values are calculated from a value obtained by integrating Y signals calculated from RGB signals for one field (screen). This is converted into a gradation.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block circuit diagram schematically showing the entire multi-panel display device, and FIG. 2 is a block diagram showing the AP of FIG.
FIG. 3 is a block diagram showing the L detection circuit 20 and the γ correction curve selection signal generation circuit 21 in detail, and FIG. 3 is a diagram for explaining a video signal conversion circuit. 4 is an internal block circuit diagram of the gamma correction curve switching circuit 21, and FIG. 5 is a timing chart of the gamma correction curve switching circuit 21 of FIG.

First, the multi-panel display of FIG.
For example, four plasma display panels (PD
P) Four video signal processing circuits 100, 200, 30 for supplying video signals 36 for the display panel to 1-4 respectively.
0 and 400 are provided. Each video signal processing circuit 10
Since 0 to 400 have basically the same configuration, the internal configuration of circuits other than the video signal processing circuit 100 is omitted for simplicity.

Therefore, the video signal processing circuit 100 will be described as a representative. First, input a composite signal (C-V)
15 is supplied from, for example, a VTR device or a tuner circuit. The input composite signal 15 is separated into an analog RGB signal 17 by an analog signal processing circuit 16. Further, the composite signal 15 is output from the synchronization separation circuit 23.
Then, the clock signal is separated into a vertical synchronizing signal 25 and a horizontal synchronizing signal (H), and a system clock CLK having a frequency of an integral multiple which is synchronized with the horizontal synchronizing signal by the PLL circuit 24 is generated from the horizontal synchronizing signal (H).

The clock signal CL thus generated
Using K, the analog RGB signal 17 sampled at the timing of the clock signal CLK is A / D-converted by the digital signal processing circuit 18 to generate, for example, an 8-bit digital RGB signal 19. The digital RGB signal 19 is supplied to the video signal conversion circuit 22 and A
It is supplied to the PL detection circuit 20.

APL (Average Picture)
FIG. 2 shows a detailed diagram of the Level (average video level) detection circuit 20 and the γ correction curve selection signal generation circuit 21. In the APL detection circuit 20, first, as shown in FIG.
At 1, the Y signal is calculated. The calculation of the Y signal is performed by the following equation.

[0030]

## EQU1 ## Y = (0.3125 × R) + (0.5625 ×
G) + (0.1250 × B) The Y signal generated in this manner is integrated for one field (for one screen) by the data arithmetic unit 42, and the integrated value is calculated by the encoding circuit 43 for the γ correction curve. (For example, 32 curves). In the case of 32 gradations, the encoded signal is a 5-bit signal. An encoded signal having such a gradation is used as the internal selection signal 29 as γ.
It is input to the correction curve switching circuit 33.

Next, a case where an enlarged image is displayed on the four display panels 1-4 will be described. In this case, the video signal processing device 100 becomes a master circuit, and the other video signal processing circuits 200, 300, and 400 become slave circuits.

First, the internal selection signal 29 is stored in the memory of the control unit 26 from the output terminal 35 via the gamma correction curve switching circuit 33. Since the output terminal 35 is connected in common to all the video signal processing circuits 100 to 400, the internal selection signal is output to each video signal at the timing of the γ selection signal read timing signal 31 from the control unit 26 in the master circuit, for example. The signals are supplied, for example, in chronological order from the output terminal 35 of the processing circuit.

In this way, the arithmetic unit 28 calculates the average value of the four internal selection signals 29 (32 gradations), which are signals indicating the brightness of each display panel supplied to the control unit 26, The same selection signal 30 (shown also as an externally generated γ selection signal in the figure) common to the four display panels is generated and supplied to the γ correction curve switching circuit 33 in each of the video signal processing circuits 100-400.

The gamma correction curve switching circuit 33 switches to the same selection signal 30 by an inside / outside switching signal 32 supplied from the control unit 26, for example.
The correction curve selection signal 34 is supplied to the video signal conversion circuit 22. The video signal conversion circuit 22 refers to the look-up table stored in the ROM in advance according to the correction curve from the input digital RGB signal 22 and the γ correction curve selection signal 34, and corrects the corrected display panel signal. The video signal 36 is output and supplied to each display panel 1-4.

When the four display panels 1-4 individually display an image, the gamma correction may be performed for each display panel. Therefore, the controller 26 controls the internal / external switching signal 32 to select the internal selection signal. The internal selection signal 29 is selected by the γ-correction curve switching circuit 33 according to the above, and is supplied to the video signal conversion circuit 22 as the γ-correction curve selection signal 34.

FIG. 3 is a detailed diagram of the video signal conversion circuit 22. As shown in the figure, the digital RGB signal 19 (8 bits each) and the gamma correction curve selection signal 34 (5 bits) are input to the ROM 44 of the look-up table as address signals, and are stored in advance at the addresses of the addresses. The video signal 36 for the display panel, which is the digital RGB signal after the gamma correction, is output as the output of the ROM.

FIG. 4 is a block circuit diagram showing details of the gamma correction curve switching circuit 33 in the video signal processing circuit 100. FIG. 5 shows a timing chart of the internal signals.

The gamma correction curve switching circuit 3 shown in FIG.
3 includes an internal selection signal 29 (shown as an internally generated γ selection signal in the figure), the same selection signal 30 (also shown as an externally generated γ selection signal in the figure), a load signal synchronized with the vertical synchronizing signal 25, and an internal / external switching. Signal 32, system clock signal CL
K, an internal selection signal read timing signal 31 is supplied.

The internal circuit configuration includes a first flip-flop circuit (D.FF with load) 51 that takes in the internal selection signal 29 with the load signal 25, an identical selection signal 30 and the output Q1 of the first flip-flop 51. , A delay flip-flop 54 that delays the load signal 29 by one system clock CLK, and a second flip-flop 53 that takes in the output of the selector 52 by the delayed load signal. Is provided. Further, there is provided a shift register 55 that serially outputs the output Q1 of the first flip-flop 51 in accordance with the internal selection signal read timing signal 31 from the control unit 26.

The operation of the gamma correction curve switching circuit 33 is as follows. As shown in the timing chart of FIG. 5, a signal of field 1 (temporally the first field) is input as a video signal as a composite signal, and the Y signal is integrated for one field by the APL detection circuit 20 as described above. The encoded internal selection signal 29 is supplied to the switching circuit 33. Then, the vertical synchronization signal 25
In response to the falling edge of the load signal ((c) in the figure) synchronized with the internal clock signal (1), the internal selection signal 29 delayed by one field is output to the output Q1 of the first flip-flop 51 at the timing of the system clock CLK ((7) d)).

On the other hand, the internal selection signal 29 of the output terminal Q1 of the first flip-flop 51 is a one-bit unit serial-parallel converted from the shift register 55 at the timing of the internal selection signal read timing signal 31 from the control unit 26. Is supplied to the control unit 26 of the master circuit. Then, the control unit 26 performs the arithmetic processing as described above, and supplies the same selection signal 30 common to the four display panels to the switching circuit 33.

Then, according to the inside / outside switching signal 32,
The selector circuit 52 switches between the same selection signal 30 and the internal selection signal 29, and the delay flip-flop 54 receives the fall of the load signal Q4 ((e) in FIG. CLK
, The output Q of the second flip-flop 53
The γ correction curve selection signal 34 switched to 3 is output ((f) in the figure).

Next, a case where one image is displayed on the display panels 1 and 2 and another image is displayed on the display panels 3 and 4 will be described. Each video signal processing circuit 100-400
Have a control unit 26 and a gamma correction curve switching circuit 33 shown in FIG. Therefore, when displaying an image on a plurality of panels, for example, if the video signal processing circuit corresponding to the display panel with the lowest number is determined to operate as a master circuit, then the above-described master circuit and slave circuit are used as the master circuit and the slave circuit. By fulfilling the function, an enlarged display can be performed by a plurality of display panels in various combinations. Same selection signal 30, internal selection signal timing signal 3
1. By connecting the internal / external switching signal 32, output signal 35, and the like to each control circuit 26 via a common bus line, adding an address to each signal, transmitting the signal, and providing a circuit for decoding the address on the receiving side. , It is possible.

[0044]

As described above, according to the present invention, when one image is enlarged and displayed on a plurality of display panels, the image for the display panel corrected in accordance with the same γ correction curve in all display panels. Since the signal is used, there is no variation in the brightness of the enlarged and displayed image, and a more natural enlarged display can be performed.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram schematically showing an entire multi-panel display device of the present invention.

FIG. 2 is a detailed block diagram of an APL detection circuit 20 and a gamma correction curve selection signal generation circuit 21 of FIG.

FIG. 3 is a diagram illustrating a video signal conversion circuit.

FIG. 4 is an internal block circuit diagram of a gamma correction curve switching circuit 21.

FIG. 5 is a timing chart of the gamma correction curve switching circuit 21.

FIG. 6 is a diagram showing a state in which four display panels are displaying enlarged images.

FIG. 7 is a diagram of a γ correction curve for explaining dynamic γ correction.

FIG. 8 is a block circuit diagram of a conventional display device.

[Explanation of symbols]

 1, 2, 3, 4 Display panel 100-400 Video signal processing circuit 20 APL detection circuit 21 Gamma correction curve selection signal generation circuit 22 Video signal conversion circuit 26 Control unit 29 Internal selection signal 30 Same selection signal 31 Internal selection signal read timing Signal 32 Internal / external switching signal 33 γ correction curve switching circuit 34 γ correction curve selection signal 36 Video signal for display panel 41 Y signal generation circuit 42 Integration circuit 51, 53 First and second flip-flop circuit 52 Selector circuit

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04N 5/202 H04N 5/66 H04N 9/69 G09G 3/28 G09G 5/10

Claims (8)

(57) [Claims] A plurality of display panels provided adjacent to each other for displaying a video, and a plurality of video signal processing circuits for inputting video signals and supplying each display panel with a video signal for each display panel; When displaying an enlarged image on the plurality of display panels,
Selecting the same γ correction curve based on the brightness signal corresponding to the brightness of each video supplied from a plurality of video signal processing circuits corresponding to the plurality of display panels used for the enlarged display, A control unit that supplies the same selection signal to a plurality of video signal processing circuits, wherein the plurality of video signal processing circuits perform correction on the video signal according to the same γ correction curve. Multi-panel display device. 2. The video signal processing circuit according to claim 1, wherein one of the plurality of video signal processing circuits corresponding to the plurality of display panels used for the enlarged display has the control means as a master circuit. The other video signal processing circuit among the plurality of video signal processing circuits supplies the brightness signal to the master circuit as a slave circuit, inputs the same selection signal, and converts the video signal according to the same γ correction curve. A multi-panel display device comprising a correction. 3. The video signal processing circuit according to claim 1, wherein the plurality of video signal processing circuits are based on a brightness signal corresponding to a brightness of a video of a corresponding display panel.
When an internal selection signal for selecting a γ correction curve is generated and an image is displayed on a single panel, a correction based on a predetermined γ correction curve is performed according to the internal selection signal, and when displaying an image on a plurality of display panels, A predetermined γ according to the same selection signal
A multi-panel display device that performs correction using a correction curve. 4. The method according to claim 3, wherein the internal selection signal is an R signal separated and extracted from the video signal.
The Y signal for each pixel is calculated from the GB signal, the Y signal for one screen is integrated, the integrated value is converted into a predetermined gray level, and the signal having the predetermined gray level is used as an internal selection signal. A multi-panel display device. 5. The video signal processing circuit according to claim 4, wherein the plurality of video signal processing circuits supply the internal selection signal to the control means as the brightness signal, and the control means controls a gradation of the supplied internal selection signal. A multi-panel display device which calculates an average among the plurality of panels and supplies a signal including the average gray scale to the plurality of video signal processing circuits as the same selection signal. 6. The video signal processing circuit according to claim 5, wherein the plurality of video signal processing circuits display the video on the single display panel and the video on the plurality of display panels using the internal selection signal and the same selection signal. A gamma correction curve switching circuit that switches between when the gamma correction curve is selected, a gamma correction curve selection signal output from the gamma correction curve switching circuit, and the video signal are input, and a display after the gamma correction according to a look-up table created in advance. A multi-panel display device comprising: a video signal conversion circuit that outputs a panel video signal. 7. The circuit according to claim 6, wherein the gamma correction curve switching circuit comprises: a first flip-flop circuit for loading the internal selection signal with a first load signal synchronized with a vertical synchronization signal; A selector circuit for switching between an output signal of a flip-flop circuit and the same selection signal; and loading the output signal of the selector circuit with a second load signal delayed by a predetermined time from the first load signal; A second flip-flop circuit for outputting a selection signal. 8. A multi-function device according to claim 7, wherein an output signal of said first flip-flop circuit is read by said control means in accordance with a read timing signal supplied at a predetermined timing from said control means. Panel display device.