WO2019186746A1

WO2019186746A1 - Led display system, led display control device, and led display device

Info

Publication number: WO2019186746A1
Application number: PCT/JP2018/012654
Authority: WO
Inventors: 勲米岡; 浅村　吉範
Original assignee: 三菱電機株式会社
Priority date: 2018-03-28
Filing date: 2018-03-28
Publication date: 2019-10-03

Abstract

The purpose of the present invention is to minimize power consumption in each sub display system to which power is supplied by each power supply device and minimize the power consumption in the entire LED display system which includes an LED display control device and an LED display device for displaying a video on the basis of a video signal delivered by the LED display control device. An LED display system 300 comprises sub display systems, power supply devices 301, 302, 303, and an LED display control device 200. The LED display control device 200 comprises correction coefficient calculation units 38, 39, 40 for first, second and third sub areas, a correction coefficient calculation unit 37 for the entire area, a common correction coefficient calculation unit 41, and a video signal delivery unit 34. Each basic LED unit 100 includes a plurality of LEDs 1 that serve as pixels, a luminance adjustment section 5, and an LED driver 6.

Description

LED display system, LED display control device, and LED display device

The present invention includes an LED display control device and an LED display device that displays video by controlling blinking of individual LEDs (Light Emitting Diodes) based on video signals distributed from the LED display control device. The present invention relates to an LED display system provided, and more particularly to an LED brightness control technique.

The LED display device includes a plurality of LEDs as display pixels, and is widely used for advertisement display indoors and outdoors due to the technological development and cost reduction of the LEDs. Until now, LED display devices have mainly displayed moving images such as natural images and animations. However, the viewing distance is shortened as the pixel pitch becomes narrower, so conferences and monitoring are possible in indoor applications. It is also used for such applications. Especially in monitoring applications, LED display devices often display images that are close to still images input from, for example, a personal computer.

In general, LEDs of three primary colors of R, G, and B are used as display pixels of the LED display device. In the LED display device, color tone is expressed by PWM (Pulse Width Modulation) control of the light emission time of each of the R, G, and B LEDs. However, since the LED consumes the maximum power in the lighting state and consumes almost no power in the non-lighting state, for example, in the case of a 20% gray signal with respect to a full-bit all white signal, the power consumption of the LED is about 20%. Thus, in the LED display device, power consumption varies greatly depending on the content of the video signal. In the full-bit all white signal, the R, G, and B color LEDs emit light at a duty ratio of 100%, and in the 20% gray signal, the R, G, and B color LEDs emit light at a duty ratio of 20%. To do.

Therefore, Patent Document 1 discloses a display device that realizes power saving by suppressing an increase in power supply capacity. In the display device described in Patent Document 1, the current value flowing through the display panel is predicted based on the input video signal. When the sum of current values in units of frames exceeds a predetermined threshold value, the display device performs video signal processing for correcting the contrast and brightness of the image, and the current value flowing through the display panel reaches a predetermined maximum value. Control not to exceed the value.

JP 2004-30981 A

Generally, a large screen is configured using a plurality of LED display devices. For example, a full HD (1920 × 1080 pixels) image is displayed by combining an LED display device of 320 × 180 pixels with a total of 36 units of 6 units in the horizontal direction and 6 units in the vertical direction. Each LED display device consumes the maximum power when displaying a full-bit all white signal, and the amount of power consumption becomes a rated value. Therefore, in the system having the FullHD resolution as described above, it is necessary to prepare a power capacity equivalent to the power consumption amount of the LED display device × 36 units.

However, there are many images that can be displayed with relatively low power consumption such as gray background or light color for monitoring purposes, and it is excessive to prepare an LED display device having the maximum power capacity calculated from the rated value. Often. In addition, there is a problem that additional power construction is required when the existing equipment capacity is insufficient in spite of being excessive.

Here, the technique described in Patent Document 1 controls power consumption by adjusting the dynamic range of the entire video from the total or average value of one frame of the video signal displayed on the monitor. On the other hand, when one screen image is displayed by combining a plurality of LED display devices, it is necessary to divide the power supplied to the LED display device. For example, when supplying power to a 6-unit LED display device using a 1-unit power supply device, a 6-unit power supply device is required. In some cases, the power capacity exceeds the power supply unit to be supplied.

Therefore, the present invention provides an LED display system including an LED display control device and an LED display device that displays an image based on a video signal distributed from the LED display control device. It aims at suppressing the power consumption for every display system, and the power consumption of the whole LED display system.

The LED display system according to the present invention supplies power to n (n is an integer of 2 or more) sub-display systems each having a plurality of LED display devices and to the plurality of LED display devices included in each of the sub-display systems. N power supply devices to supply, and at least one LED display control device that distributes video signals to the plurality of LED display devices of each of the sub-display systems, and at least one LED display control The apparatus calculates an average luminance value of pixels in a display area included in each of the sub display systems in the video signal, and based on the average luminance value, power consumption of each of the sub display systems is equal to or less than a predetermined value. N sub-area correction coefficient calculating units for calculating a luminance correction coefficient for each display area for correcting the luminance of the video signal so that An average luminance value of pixels of one entire screen in the video signal is calculated, and based on the average luminance value, the power consumption of the n sub-display systems as a whole is less than or equal to a predetermined value. Based on the calculation results of the entire area correction coefficient calculation unit for calculating the luminance correction coefficient for the entire screen, n sub-area correction coefficient calculation units, and the entire area correction coefficient calculation unit for correcting the luminance. A common correction coefficient calculation unit that calculates a common luminance correction coefficient, and a video signal distribution unit that distributes the video signal and the common luminance correction coefficient to the plurality of LED display devices included in the n sub display systems. Each of the LED display devices includes a plurality of LEDs serving as display pixels and the video signal distribution based on the common luminance correction coefficient distributed from the video signal distribution unit. A luminance adjusting unit that adjusts the luminance of the video signal distributed from the LED, and an LED driving unit that drives the plurality of LEDs based on the video signal whose luminance is adjusted by the luminance adjusting unit. is there.

According to the present invention, the LED display device can display an image based on a common luminance correction coefficient calculated based on the luminance correction coefficient for each display area and the luminance correction coefficient for the entire screen calculated in the LED display control apparatus. Since the luminance of the signal is adjusted, it is possible to suppress power consumption for each sub display system and power consumption of the entire LED display system.

The objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description and the accompanying drawings.

1 is a configuration diagram of an LED display system according to Embodiment 1. FIG. It is a block diagram which shows an example of a structure of a unit LED unit. It is a block diagram which shows an example of a structure of a LED display control apparatus. It is a timing chart of the signal processing in an LED display system. It is explanatory drawing for demonstrating the display pattern of a LED display system. It is a block diagram of LED display system 300A which concerns on Embodiment 2. FIG. It is explanatory drawing for demonstrating the timing which calculates a common luminance correction coefficient based on the average luminance value input via the signal line. It is a circuit diagram around the average luminance value communication unit.

<Embodiment 1>
Embodiment 1 of the present invention will be described below with reference to the drawings.

(Configuration of LED display system)
Initially, the whole structure of the LED display system 300 which concerns on Embodiment 1 of this invention is demonstrated. FIG. 1 is a configuration diagram of an LED display system 300.

As shown in FIG. 1, the LED display system 300 includes an LED unit 101, an LED display control device 200, and

power supply devices

301, 302, and 303. The LED unit 101 displays a video based on a video signal distributed from the LED display control device 200.

The LED unit 101 includes a plurality of LED display devices (hereinafter also referred to as “unit LED units”) 100, and one LED display unit 5 (see FIG. 2) included in each of the plurality of unit LED units 100 has one unit. The screen is configured. In the example of FIG. 1, the LED unit 101 includes one unit LED unit 100 of a total of 18 units of 6 units in the horizontal direction × 3 units in the vertical direction. In FIG. 1, the unit LED unit 100 is indicated by an outer square frame and an inner square frame, the outer square frame indicates the whole, and the inner square frame indicates a portion that handles an electric signal.

In the first embodiment, the pixel configuration of the unit LED unit 100 is 320 pixels in the horizontal direction × 180 pixels in the vertical direction, and the LED unit 101 displays Full HD (1920 × 1080 pixels) by the unit LED unit 100 of 18 units.

Furthermore, power is supplied to the LED unit 101 from three units of

power supply devices

301, 302, and 303. Specifically, power is supplied from each

power supply device

301, 302, 303 to a total of 6 unit LED units 100.

The LED display control device 200 performs distribution of video signals to the LED unit 101 and control of the LED unit 101. In the present embodiment, since the LED display control device 200 controls the plurality of unit LED units 100, the plurality of unit LED units 100 are divided into three sub display systems, and a video signal and a control signal from the control device 200 are divided. Are daisy chain connected to the unit LED units 100 in each sub display system. Each sub-display system has 6 unit LED units 100. The method by which the LED display control device 200 controls each unit LED unit 100 will be described in detail later.

(Configuration of unit LED unit)
FIG. 2 is a block diagram showing an example of the configuration of the unit LED unit 100 according to Embodiment 1 of the present invention. As shown in FIG. 2, the unit LED unit 100 includes a video input terminal 2, a video output terminal 3, an input circuit 51, a video signal processing circuit 4, a frame memory 50, a luminance adjustment unit 5, an LED drive unit 6, and an LED display unit. 7, a microcomputer 8, a memory 9, a control terminal 10, a power input terminal 11, a power output terminal 12, and a power circuit 52.

The power supplied from the power supply device 301 is supplied to the power circuit 52 in the unit LED unit 100 via the power input terminal 11 of each unit LED unit 100, and each circuit in the unit LED unit 100 via the power circuit 52. Is supplied with power. Further, the power supplied through the power input terminal 11 is supplied to the unit LED unit 100 at the next stage through the power output terminal 12, whereby a daisy chain of power supply is performed.

From the LED display control device 200, in order to reduce the number of signal lines constituting the transmission path, the video signal is converted into a serial signal and output, and input to the video input terminal 2. In the input circuit 51, the serial signal input via the video input terminal 2 is decoded and output to the video signal processing circuit 4, and further, the serial signal is buffered and output via the video output terminal 3. The video signal output from the video output terminal 3 is connected to the video input terminal 2 of each unit LED unit 100 in the next stage as a daisy chain signal.

The video signal processing circuit 4 uses the frame memory 50 to perform signal processing such as processing for selecting an area necessary for display from the video signal decoded by the input circuit 51. The luminance adjusting unit 5 adjusts the luminance of the video signal that has been subjected to signal processing by the video signal processing circuit 4 based on a luminance correction coefficient distributed from the LED display control device 200, which will be described later.

The LED driving unit 6 PWM drives the LED display unit 7 based on the video signal whose luminance has been adjusted by the luminance adjusting unit 5. The LED display unit 7 is configured by arranging LEDs 1 serving as display pixels in a matrix of 320 horizontal pixels × 360 vertical pixels. The LED 1 includes three red (R), green (G), and blue (B) LEDs per pixel. The LED display unit 7 is driven by the LED driving unit 6 based on the video signal, and displays an image.

The control terminal 10 is an input / output terminal for a communication control signal between the LED display control device 200 and the unit LED unit 100. The microcomputer 8 controls the video signal processing circuit 4, the luminance adjustment unit 5, and the LED driving unit 6, and stores setting information distributed from the LED display control device 200 through the control terminal 10 in the memory 9.

(Configuration of LED display control device)
FIG. 3 is a block diagram showing an example of the configuration of the LED display control device 200 according to Embodiment 1 of the present invention. As shown in FIG. 3, the LED display control device 200 includes a video input terminal 30, a video signal processing circuit 31, a video signal distribution unit 34, a memory 35, a control circuit 33,

video output terminals

17, 18 and 19, and a control terminal 21. , 22, 23, and an external terminal 20, an external synchronization signal input / output terminal 36, an average luminance value communication unit 43, and an average luminance value input / output terminal 42.

A video signal from an external device such as a PC is input to the video input terminal 30. The video signal processing circuit 31 performs video signal processing such as gamma correction of the video signal input from the video input terminal 30. The video signal distribution unit 34 divides the video signal that has been subjected to signal processing by the video signal processing circuit 31 and distributes it to the LED unit 101 via the video output terminals 17 to 19. In this case, the video signal is converted to a serial signal and output in order to reduce the number of signal lines constituting the transmission path.

Also, in order to synchronize the outputs of the LED display control devices 200 of a plurality of units, the video signal processing circuit 31 has a function of synchronizing with an external synchronization signal input / output from the external synchronization signal input / output terminal 36. The operation of the external synchronization function will be described in detail later.

The control circuit 33 includes an overall area correction coefficient calculation unit 37, a first sub area correction coefficient calculation unit 38, a second sub area correction coefficient calculation unit 39, a third sub area correction coefficient calculation unit 40, a common correction coefficient calculation unit 41, An external communication unit 26, a communication unit 27, and a setting unit 28 are provided.

The external communication unit 26 receives a control signal for controlling the LED display control device 200 and the unit LED unit 100 input from an external device such as a PC via the external terminal 20. The received control signal is stored in the setting unit 28 as a control parameter of the control circuit 33. The communication unit 27 transmits and receives control signals to and from the unit LED unit 100 via the control terminals 21 to 23.

The whole area correction coefficient calculating unit 37 calculates the average luminance value of the pixels of one frame of the video signal that has been subjected to the signal processing by the video signal processing circuit 31, that is, the entire screen. Then, the entire area correction coefficient calculation unit 37 corrects the luminance of the video signal based on the calculated average luminance value so that the power consumption of the LED unit 101 that is the entire sub display system is equal to or less than a predetermined value. The luminance correction coefficient Cyall for one entire screen is calculated.

The first sub-area correction coefficient calculation unit 38 averages pixels in the first sub-area that is a display area formed by the unit LED units 100 with ID = 1 to 6 that are sub-display systems that are powered by the power supply device 301. A luminance value is calculated. The first sub-area correction coefficient calculation unit 38 corrects the luminance of the video signal based on the calculated average luminance value so that the power consumption of the first sub-area is not more than a predetermined value. The luminance correction coefficient Cys1 for one subarea is calculated.

Similarly, the second sub-area correction coefficient calculation unit 39 calculates the average luminance of the pixels constituting the second sub-area that is the display area constituted by ID = 7 to 12 that is the sub-display system supplied with power by the power supply device 302. Calculate the value. Then, the second sub-area correction coefficient calculation unit 39 calculates a luminance correction coefficient Cys2 for correcting the luminance of the video signal so that the power consumption of the second sub-area is not more than a predetermined value.

The third sub-area correction coefficient calculation unit 40 calculates the average luminance value of the pixels constituting the third sub-area which is a display area constituted by ID = 13 to 18 which is a sub-display system supplied with power by the power supply device 303. calculate. Then, the third sub-area correction coefficient calculation unit 40 calculates a luminance correction coefficient Cys3 for correcting the luminance of the video signal so that the power consumption of the third sub-area is not more than a predetermined value.

The common correction coefficient calculation unit 41 calculates a common luminance correction coefficient Cy based on the luminance correction coefficients Cyall, Cys1, Cys2, and Cys3. The operations of the entire area correction coefficient calculation unit 37, the first sub area correction coefficient calculation unit 38, the second sub area correction coefficient calculation unit 39, the third sub area correction coefficient calculation unit 40, and the common correction coefficient calculation unit 41 will be described later. Will be described in detail. The calculation result of the common correction coefficient calculation unit 41 can synchronize the power consumption control of the LED display control devices 200 of a plurality of units via the average luminance value communication unit 43 and the average luminance value input / output terminal 42.

(LED brightness correction method)
Next, a method for correcting the brightness of LED 1 in LED display system 300 according to the present embodiment will be described in detail.

As shown in FIG. 1, when configuring an LED display system 300 including an LED display control device 200 and an LED unit 101 composed of 18 unit LED units 100, the LED display control device 200 is individually unit LED. In order to control the unit 100, an ID number is set in each unit LED unit 100. In the example of FIG. 1, ID = 1 to 18 are set in the unit LED unit 100 of 18 units. The ID number of the unit LED unit 100 is stored in the memory 9 in each unit LED unit 100.

In the example of FIG. 1, the LED unit 101 is divided into a sub-display system composed of unit LED units 100 with ID = 1-6, a sub-display system composed of unit LED units 100 with ID = 7-12, and ID = 13-18 The unit LED unit 100 is divided into three sub display systems, and the unit LED units 100 having ID = 3, ID = 9, and ID = 15 are connected to the LED display control device 200.

Specifically, the video output terminals 17 to 19 of the LED display control device 200 are connected to the video input terminal 2 of the unit LED unit 100 with ID = 3, 9, 15 respectively. Similarly, the control terminals 21 to 23 of the LED display control device 200 are connected to the control terminal 10 of the unit LED unit 100 of ID = 3, 9, 15 respectively.

Further, as shown in FIG. 1, the power supply device 301 supplies power to the unit LED units 100 with ID = 1 to 6, and the power supply device 302 supplies power to the unit LED units 100 with ID = 7 to 12. . The power supply device 303 supplies power to the unit LED units 100 with ID = 13 to 18. Specifically, the power output supplied from the

power supply devices

301, 302, and 303 is connected to the power input terminal 11 of the unit LED unit 100 with ID = 1, 7, and 13, respectively, and the next through the power output terminal 12 By connecting to the power input terminal 11 of the unit LED unit 100 of the stage, power is supplied to the unit LED units 100 of 6 units.

As shown in FIG. 3, in the LED display control device 200, the video signal input from the video input terminal 30 is subjected to processing such as gamma correction in the video signal processing circuit 31, to the resolution of the LED unit 101 that is the output destination. Converted. In the present embodiment, this resolution is 1920 × 1080 pixels (FullHD).

The video signal processed by the video signal processing circuit 31 is divided into three display areas of 640 × 1080 pixels by the video signal distribution unit 34 and then ID = 1 to 6, 7 to 12, and 13 respectively. It is distributed to three sub-display systems consisting of ˜18 unit LED units 100.

The video signal processed by the video signal processing circuit 31 is delivered to the LED unit 101 by the video signal delivery unit 34. In the entire area correction coefficient calculation unit 37, the first sub-area correction coefficient calculation unit 38, the second sub-area correction coefficient calculation unit 39, and the third sub-area correction coefficient calculation unit 40, the average luminance value of the pixels in each display area and A luminance correction coefficient is calculated.

(Brightness correction coefficient calculation method)
Hereinafter, a method for calculating the luminance correction coefficient will be described in detail. In the present embodiment, the resolution of the video signal processed by the video signal processing circuit 4 as described above is 1920 × 1080 pixels. R, G, and B luminance values are output for each pixel. The luminance value of each color of R, G, B for each pixel with the upper left coordinate of the display area of the LED unit 101 being (h, v) = (1, 1) and the lower right coordinate being (h, v) = (1920, 1080). Is represented as Yr (h, v), Yg (h, v), Yb (h, v).

In the whole area correction coefficient calculation unit 37, the average value of Yr from (h, v) = (1, 1) to (1920, 1080) is YR_av_all, the average value of Yg is YG_av_all, and the average value of Yb is YB_av_all. Then, the average luminance value Y_av_all for one frame in the entire area is calculated by Expression (1).

In the above calculation formula, the average luminance value of each of R, G, and B is added for three colors and divided by the number of pixels, but the method is not limited to this. For example, the average luminance value may be obtained using the sum of one frame of Yr, Yg, Yb.

Similarly, in the first sub-area correction coefficient calculation unit 38, the average value of Yr from (h, v) = (1, 1) to (640, 1080) is YR_av_S1, the average value of Yg is the average of YG_av_S1, and Yb. Assuming that the value is YB_av_S1, the average luminance value Y_av_S1 for one frame of the first sub-area is calculated by equation (2).

Similarly, in the second sub-area correction coefficient calculation unit 39, the average value of Yr from (h, v) = (641, 1) to (1280, 1080) is YR_av_S2, the average value of Yg is YG_av_S2, and the average of Yb. Assuming that the value is YB_av_S2, the average luminance value Y_av_S2 for one frame of the second sub-area is calculated by Expression (3).

Similarly, in the third sub-area correction coefficient calculator 40, the average value of Yr from (h, v) = (1281, 1) to (1920, 1080) is YR_av_S3, the average value of Yg is YG_av_S3, and the average of Yb. Assuming that the value is YB_av_S3, the average luminance value Y_av_S3 for one frame of the third sub-area is calculated by Expression (4).

Here, the luminance values Yr (h, v), Yg (h, v), and Yb (h, v) of the R, G, and B colors are 8 bits (values from 0 to 255), that is, 256 gradations. Then, the average luminance values Y_av_all, Y_av_S1, Y_av_S2, and Y_av_S3 for one frame in the entire area and the first to third sub areas are in the range of 0 to 255.

The setting unit 28 stores the power control adjustment value P_all for the entire area and the power control adjustment values P_S1, P_S2, and P_S3 for the first to third sub areas. The entire area power control adjustment value P_all and the first to third sub-area power control adjustment values P_S1, P_S2, and P_S3 can be set in advance by the user from the external terminal 20 through the external communication unit 26.

For example, the power control adjustment value P_all for the entire area is an all white full bit signal that is a product rated value when all pixels are lit at the maximum luminance value (R = 255, G = 255, B = 255). It is set to what percentage or less of the maximum power consumption can be used. For example, P_all = 50% is set.

The entire area correction coefficient calculation unit 37 distributes the luminance correction coefficient Cyall to the unit LED unit 100 based on the entire area power control adjustment value P_all set in the setting unit 28 and the average luminance value Y_av_all calculated for each frame. To decide. Specifically, the overall area correction coefficient calculation unit 37 uses, for example, 127.5 which is 50% of the maximum value 255 that Y_av_all can take as a threshold, and the average luminance value Y_av_all for each frame exceeds 127.5. Then, a luminance correction coefficient Cyall that reduces the average luminance of the one frame below the threshold value is calculated.

Here, assuming that the luminance correction coefficient Cyall is an accuracy of 9 bits,
If Y_av_all ≤ 255 x P_all, Cyall = 256,
In the case of Y_av_all> 255 × P_all, the luminance correction coefficient Cyall is calculated by equation (5).

For example, when P_all = 0.5 and Y_av_all = 255, Cyall = 128.

Similarly for the first sub-area,
If Y_av_S1 ≤ 255 x P_S1, CyS1 = 256
In the case of Y_av_S1> 255 × P_S1, the luminance correction coefficient CyS1 is calculated by the equation (6).

Similarly, for the second subarea,
If Y_av_S2 ≤ 255 x P_S2, CyS2 = 256
In the case of Y_av_S2> 255 × P_S2, the luminance correction coefficient CyS2 is calculated by Expression (7).

Similarly for the third sub-area,
If Y_av_S3 ≤ 255 x P_S3, CyS3 = 256
In the case of Y_av_S3> 255 × P_S3, the luminance correction coefficient CyS3 is calculated by Expression (8).

Next, the common correction coefficient calculation unit 41 selects the minimum value of the luminance correction coefficients Cyall, CyS1, CyS2, and CyS3 by the equation (9), and the common luminance correction coefficient Cy (hereinafter simply referred to as “brightness correction”) for one frame. (Also referred to as coefficient Cy).

As described above, in order to calculate the common luminance correction coefficient Cy for one entire frame, video data for one frame is required. However, the video signal output from the video signal processing circuit 31 is an entire area correction coefficient. The calculation unit 37, the first sub-area correction coefficient calculation unit 38, the second sub-area correction coefficient calculation unit 39, the third sub-area correction coefficient calculation unit 40, and the video signal distribution unit 34 are simultaneously input in time series. Therefore, when the luminance correction coefficient Cy for one frame is determined, the video signal is distributed to the LED unit 100 via the video signal distribution unit 34.

The luminance correction coefficient Cy is the head of the next frame of the frame in which the average luminance values Y_av_all, Y_av_S1, Y_av_S2, and Y_av_S3 are calculated as described above, that is, Yr (1,1), Yg (1,1), Yb (1,1). And is distributed to the LED unit 100 via the video signal distribution unit 34.

The luminance correction coefficient Cy is distributed to the LED unit 100 in a form delayed by one frame with respect to the video data. FIG. 4 is a timing chart of signal processing in the LED display system 300.

In the video signal processing circuit 4 of the unit LED unit 100 with ID = 1 to ID = 6, Yr (n) (h, v), Yg (n) (h, v), Yb (n) are used as the video signals of the nth frame. (H, v) is sequentially received from (h, v) = (1, 1) to (640, 1080). Further, the video signal processing circuit 4 selects a portion to be displayed from the distributed video signal based on its own ID number stored in the memory 9.

Specifically, for example, in the unit LED unit 100 with ID = 1, the video signal processing circuit 4 selects signal areas (h, v) = (1, 1) to (320, 360). Similarly, in the unit LED unit 100 with ID = 2, the signal area of (h, v) = (1,361) to (320,720) is (h, v) in the unit LED unit 100 with ID = 3. = (1,721) to (320,1080), the signal area of (h, v) = (321,1) to (640,360) is ID = 4 in the unit LED unit 100 with ID = 4. 5 unit LED units 100 (h, v) = (321, 361) to (640, 720) signal areas are ID = 6 unit LED units 100 (h, v) = (321, 721) to The signal regions (640, 1080) are respectively selected.

In the unit LED units 100 with ID = 7-12 and ID = 13-18, the same processing as described above is performed.

Further, the LED driving unit 6 needs to control the LED display unit 7 by PWM driving the video signal in a time division manner. Therefore, the video signal processing circuit 4 rearranges the video signals input in time series at the timing required by the LED drive unit 6 via the frame memory 50. That is, the video signal processing circuit 4 causes a delay of one frame when rearranging the video signals.

The video information of the (n + 1) th frame is distributed as data distributed from the LED display control device 200 to the video signal processing circuit 4, and the luminance correction coefficient Cy (n) relating to the video signal of the nth frame is at the head. It has been added.

The microcomputer 8 reads the luminance correction coefficient Cy (n) relating to the video signal of the nth frame and outputs Yr (n) (h, v), which is output as a video signal after being delayed by one frame from the video signal processing circuit 4. The luminance adjustment unit 5 is caused to perform luminance correction according to the equation (10) for Yg (n) (h, v) and Yb (n) (h, v).

Yro (n), Ygo (n), Ybo (n) on which the above-described processing is performed by the brightness adjusting unit 5 is output to the LED driving unit 6 and displayed on the LED display unit 7 as an image.

In this embodiment, the video signal is delayed by one frame by the frame memory 50 of the unit LED unit 100. However, it is not always necessary to delay the video signal by one frame. It is only necessary that the video data input to the unit LED unit 100 and the luminance correction coefficient Cy (n) are controlled so as to coincide with each other in time.

As described above, in order to calculate the average luminance value of one frame, all the video data is necessary, so that a delay of one frame occurs. Therefore, in order to distribute the luminance correction coefficient Cy and the video signal at the same timing, it is necessary to delay the video signal by one frame in the LED display control device 200. However, in the present embodiment, a frame memory is added to the LED display control device 200 in order to match the timing of one frame delay in the LED display control device 200 using the frame delay in the unit LED unit 100. And power control in units of frames can be performed.

Next, the operation of power control will be described. The LED display system 300 shown in FIG. 1 has the maximum power consumption when an all white signal is displayed and the minimum when the all black signal is displayed. For example, if the power consumption when displaying all white in each sub-area is 1500 VA and the power consumption when displaying all black is 300 VA, the power consumption of the entire area is 4500 VA when displaying all white. The power consumption at the time is 900VA. In this case, 1500-300 = 1200 VA can be controlled by the luminance correction value (Cy / 256) in each sub-area, and 4500-900 = 3600 VA can be controlled in the entire area.

Here, when the brightness correction of the entire area is controlled to 50% or less and the brightness correction of each sub-area is controlled to 70% or less, the brightness average value is obtained when the brightness average of the entire area is 50% or more of all white. Luminance correction is performed so as to be 50%. On the other hand, in each sub-area, the luminance correction is performed so that the average luminance value becomes 70% when the average luminance in the area is 70% or more of the total white.

For example, a system is assumed in which the power consumption of the LED display system 300 as a whole is 3000 VA or less, and the allowable power that can be supplied by each of the power supply devices 301 to 303 that supplies power to each sub-area is 1200 VA or less. In this case, as shown in FIG. 5, when only the first sub area is displayed in all white, the average value of the pixels in the entire area is 255/3 = 85 <127.5.
Therefore, the luminance correction coefficient Cyall is Cyall / 256 = 1 from Equation (5). On the other hand, since the average value of the pixels is 255 in the first sub-area, the luminance correction coefficient CyS1 is CyS1 / 256 = 0.7 from Equation (6). Since the pixel average value is 0 in the second and third sub-areas, the luminance correction coefficient CyS2 is CyS2 / 256 = correction coefficient CyS3 / 256 = 1 from Expressions (7) and (8). FIG. 5 is an explanatory diagram for explaining a display pattern of the LED display system 300.

Therefore, the luminance correction coefficient of the entire area and the second and third sub areas is 100%, and the luminance correction coefficient of the first sub area is 70%. Therefore, the common luminance correction coefficient Cy is Cy / 256 = 0. 7 is selected and the overall power consumption is 1140 + 300 × 2 = 1740 VA.

In this case, the power consumption of the first sub-area is controlled to 70% and 1200 × 0.7 + 300 = 1140 VA, which is controlled to 1200 VA or less.

Here, when the power saving control for each subarea is not performed, the first power consumption is concentrated only in the first subarea as shown in FIG. 5 even if the overall power consumption is limited to 50%. No subarea power limitation. Therefore, the first sub area needs a power capacity of 1500 VA, and the power capacity is insufficient. However, usually, the power capacity is often secured for the entire system or for each of the power supply devices 301 to 303. When the entire power consumption capacity is controlled to a certain value or less, it is necessary to secure the power capacity so that the maximum power can be supplied to each of the power supply devices 301 to 303, and thus the effect of the power saving control is hardly exhibited.

On the other hand, when the power supply to the unit LED unit 100 constituting one screen is divided and performed as in the first embodiment, the power control for the entire screen and the power supply devices 301 to 303 are performed separately. By using this power control together, even if power consumption is concentrated in some sub-display systems, power consumption can be performed efficiently without power over.

Further, the LED display control device 200 calculates an average luminance value for each frame, and distributes the luminance correction coefficient selected from the average luminance value and a desired power control adjustment value at the head of the next frame. The unit LED unit 100 performs luminance adjustment using the luminance correction coefficient added to the head of the next frame while delaying one frame in order to perform processing such as cutting out the distributed video signal, so that each frame without delay. It becomes possible to suppress the power consumption below the desired power control adjustment value for each time.

Therefore, even if a video signal that instantaneously increases power consumption is input, the power consumption can be reduced in units of frames, and the LED display system 300 is controlled so that the power consumption is always below a certain level. It becomes possible. For this reason, it is not necessary to unnecessarily reduce the luminance even for a video signal with low power consumption, and it is possible to suppress a decrease in luminance of the LED display system 300 as a whole.

(effect)
As described above, the LED display system 300 according to Embodiment 1 is based on the luminance correction coefficients CyS1, CyS2, CyS3 for each display area and the luminance correction coefficient Cyall for one entire screen, which are calculated by the LED display control device 200. Since the luminance of the video signal is adjusted based on the common luminance correction coefficient Cy calculated in this way, it is possible to suppress the power consumption of each sub display system and the power consumption of the LED display system 300 as a whole. As described above, energy consumption in the LED display system 300 can be reduced.

When power is supplied to three sub display systems, if power saving control is performed on the entire screen, power control is not performed when power is concentrated on some sub display systems. For this reason, it is necessary to supply the power of the maximum power consumption of the plurality of unit LED units 100 included in the sub display system for each sub display system. In the LED display system 300 according to the first embodiment, by combining the power saving control for each sub display system and the power saving control for the entire screen, power control can be performed even if power is concentrated in some sub display systems. It can be carried out. Thereby, it is not necessary to supply the power of the maximum power consumption of the plurality of unit LED units 100 included in the sub display system, and the power saving control can be performed efficiently.

The common luminance correction coefficient Cy is calculated by the luminance correction coefficients CyS1, CyS2, and CyS3 calculated by the first, second, and third sub-area correction

coefficient calculating units

38, 39, and 40, and the entire area correction coefficient calculating unit 37. Among the brightness correction coefficients Cyall, this is the minimum brightness correction coefficient. Therefore, the power control for each sub display system and the power control for the entire LED display system 300 can be efficiently made compatible.

Further, in the LED display system 300, since the power supply devices 301 to 303 that supply power to the unit LED units 100 of 6 units, that is, the power saving control for each sub display system is used together, power is supplied to some sub display systems. Power saving control functions even if there is a concentration. Therefore, it is not necessary to supply the maximum power consumption for each of the power supply devices 301 to 304, and the efficiency of power control in the entire LED display system 300 is improved.

In the first embodiment, the power is supplied to the unit LED unit 100 of 6 units by the power supply device of 1 unit, but it is not necessarily 6 units. A configuration may be adopted in which power is supplied to the unit LED units 100 having an arbitrary number of units, and the number of unit LED units 100 supplied by each of the power supply devices 301 to 303 does not have to be the same. Further, the 18 unit LED units 100 constituting one screen are supplied with power by the three units of power supply devices 301 to 303. However, the unit LED unit 100 is not necessarily required to have three units. What is necessary is just to supply power. Further, the number of sub display systems is not necessarily three, but may be two or more.

<Embodiment 2>
Next, an LED display system 300A according to Embodiment 2 will be described. FIG. 6 is a configuration diagram of an LED display system 300A according to the second embodiment. FIG. 7 is an explanatory diagram for explaining the timing for calculating the common luminance correction coefficient Cy based on the average luminance value Yave input via the signal line. FIG. 8 is a circuit diagram around the average luminance value communication unit 43. In the second embodiment, the same components as those described in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

(Configuration with multiple unit LED display controller and multiple unit LED unit)
Next, a description will be given of a power saving control method in the case where an LED display system 300A having a pixel number of 1920 × 1080 or more is configured by the plurality of LED display control devices 200 and the plurality of LED units 100.

For example, as shown in FIG. 6, 4 units of LED

display control devices

200a, 200b, 200c, and 200d and 4 units of

LED units

101a, 101b, 101c, and 101d are connected to each other, so that an LED having a size of 7680 × 1080 pixels is obtained. A display system 300A is configured. Although not shown in FIG. 6,

power supply devices

301, 302, and 303 are connected to the LED unit 101a. The same applies to the

LED units

101b, 101c, and 101d.

In this case, each of the LED

display control devices

200a, 200b, 200c, and 200d is synchronized with the external synchronization signal input via the external synchronization signal input / output terminal 36 (see FIG. 3) in the video signal processing circuit 31. The signal is processed to control each

LED unit

101a, 101b, 101c, 101d. Further, the average luminance value Yave calculated by each of the LED

display control devices

200a, 200b, 200c, and 200d is obtained by connecting the signal line to the wired OR connection via the average luminance value input / output terminal 42 (see FIG. 3). The average luminance value Yave is shared between the LED

display control devices

200a, 200b, 200c, and 200d.

Here, the external synchronization signal input via the external synchronization signal input / output terminal 36 outputs, for example, the external synchronization signal generated by the LED display control device 200a to the remaining three units of the LED

display control devices

200b, 200c, and 200d. By doing so, the outputs of the four units of the LED

display control devices

200a, 200b, 200c, and 200d can be synchronized. Actually, as shown in FIG. 7, when a common external synchronization signal is input to each of the LED

display control devices

200a, 200b, 200c, and 200d via the external synchronization signal input / output terminal 36, each video signal processing circuit 4 generates a vertical synchronizing signal Vsync and a horizontal synchronizing signal Hsync.

In the case of FIG. 6, for example, by outputting the external synchronization signal generated by the LED display control device 200a to the remaining three units of LED

display control devices

200b, 200c, and 200d, four units of LED

display control devices

200a, 200b, 200c, All outputs 200d are synchronized at the timing shown in FIG.

Next, the operation of the average luminance value communication unit 43 will be described. The average luminance value communication unit 43 includes an average luminance value Y_av_all calculated by the entire area correction coefficient calculating unit 37, an average luminance value Y_av_S1 calculated by the first subarea correction coefficient calculating unit 38, and the second subarea. An average luminance value Yave that is the maximum value of the average luminance value Y_av_S2 calculated by the correction coefficient calculation unit 39 and the average luminance value Y_av_S3 calculated by the third sub-area correction coefficient calculation unit 40 is input. As shown in FIG. 7, the average luminance value Yave is determined when all the effective images are output. The average luminance value communication unit 43 transmits the average luminance value Yave in 8 bits. Note that the average luminance value Yave, which is the maximum value of the average luminance values Y_av_all, Y_av_S1, Y_av_S2, and Y_av_S3, is calculated by, for example, the entire area correction coefficient calculation unit 37.

As shown in FIG. 7, the average luminance value communication unit 43 transmits the average luminance value Yave [7: 0] by dividing it into four in the front porch 4H period of the video signal. That is, the average luminance value communication unit 43 transmits Yave [7: 6] to the first line of the front porch, and sequentially transmits Yave [5: 4], Yave [3: 2], and Yave [1: 0] in this order. To do.

Also, the average luminance value communication unit 43 encodes and transmits 2-bit data to the three signal lines Mul_o [2: 0]. A signal line corresponding to each bit of the signal line Mul_o [2: 0] is a signal corresponding to each bit of the signal line Mul_o [2: 0] of another LED display control device via the average luminance value input / output terminal 42. Each wire is connected with a wired OR.

Actually, as shown in FIG. 8, a digital transistor 45 and a pull-up resistor 46 are connected to the signal line corresponding to each bit of the signal line Mul_o [2: 0]. When the signal of “L” is input, “L” is output, and when the signal of “L” is input, the impedance becomes high impedance. Therefore, the LED

display control devices

200a, 200b, 200c, If “L” is output even in one unit of 200d, the signal line becomes “L”. In other cases, the signal line is “H”.

The average luminance value communication unit 43 encodes 2-bit data in accordance with three signal lines Mul_o [2: 0] as follows.
When Yave [7: 6] = 11, Mul_o [2: 0] = “100”
When Yave [7: 6] = 10, Mul_o [2: 0] = “010”
When Yave [7: 6] = 01, Mul_o [2: 0] = “001”
When Yave [7: 6] = 00, Mul_o [2: 0] = “000”
Here, the case of Yave [7: 6] is shown.

Further, for example, as shown in FIG. 7, the average luminance value communication unit 43 sets the average luminance value Yave [7: 0] to the signal line Mul_o [2: 0] at a timing delayed by ¼ cycle from Hsync in the front porch. And the transmission result Mul_i [2: 0] by the four units of LED

display control devices

200a, 200b, 200c, and 200d is fetched at the next Hsync timing. The transmission result by the four units of LED

display control devices

200a, 200b, 200c, and 200d is the maximum value of the average luminance value Yave [7: 0] of the four units of LED

display control devices

200a, 200b, 200c, and 200d. is there.

Here, in each LED

display control device

200a, 200b, 200c, 200d, Yave '[7: 6] decoded from Mul_o [2: 0] determined in the first line of the front porch and its own Yave [7: 6] And compare.
If Yave [7: 6] <Yave ′ [7: 6], then Yave [7: 6] = Yave ′ [7: 6], Yave [5: 0] = “000000”,
When Yave [7: 6] ≧ Yave ′ [7: 6], Yave [7: 0] is not changed. That is, when Yave '[7: 6] decoded is larger than its own Yave [7: 6], the maximum value correct by comparing [5: 0] bits is set by setting its own Yave [5: 0] = 0. A value can be obtained. During decoding, fraction processing is performed so that Yave '[7: 6] is any one of “100”, “010”, “001”, and “000”.

Similarly, in the second line of the front porch,
If Yave [5: 4] <Yave ′ [5: 4], then Yave [5: 4] = Yave ′ [5: 4], Yave [3: 0] = “0000”
When Yave [5: 4] ≧ Yave ′ [5: 4], Yave [5: 0] is not changed.

In the third line of the front porch,
If Yave [3: 2] <Yave ′ [3: 2], then Yave [3: 2] = Yave ′ [3: 2], Yave [1: 0] = “00”, and Yave [3: 2] ≧ In the case of Yave ′ [3: 2], Yave [3: 0] is not changed.

Finally, on the 4th line of the front porch,
If Yave [1: 0] <Yave ′ [1: 0], Yave [1: 0] = Yave ′ [1: 0]
When Yave [1: 0] ≧ Yave ′ [1: 0], Yave [1: 0] is not changed.

As described above, Yave [7: 0], which is the maximum in each LED

display control device

200a, 200b, 200c, 200d by repeating transmission in units of 2 bits, is set to each LED

display control device

200a, 200b, 200c, 200d. Can be shared within. Further, as shown in FIG. 7, the luminance correction coefficient Cy is changed after Yave [7: 0] is determined in Hsync on the fifth line of the front porch.

As described above, the luminance correction coefficient Cy is changed in each of the LED

display control devices

200a, 200b, 200c, and 200d. The luminance correction coefficient Cy is calculated based on the common average luminance value Yave [7: 0]. Therefore, the luminance correction coefficient Cy is the same. That is, the luminance correction coefficient Cy common to the LED

display control devices

200a, 200b, 200c, and 200d is calculated.

In the above description, the 8-bit average luminance value Yave [7: 0] is divided and transmitted four times between the LED

display control devices

200a, 200b, 200c, and 200d, but the number of transmission lines shown in FIG. The accuracy of the average luminance value Yave may be performed with an arbitrary number of bits. For example, the average luminance value Yave may be divided into two portions in units of 4 bits with an 8-bit accuracy and 15 transmission lines. Furthermore, although the average luminance value Yave is transmitted as transmission data transmitted between the LED

display control devices

200a, 200b, 200c, and 200d, a luminance correction coefficient Cy may be transmitted. However, in the case of the luminance correction coefficient Cy, it is necessary to select the luminance correction coefficient Cy that is the smallest among the LED

display control devices

200a, 200b, 200c, and 200d.

In the above description, the average luminance value Yave [7: 0] is transmitted in synchronization with the horizontal synchronization signal Hsync in the vertical front porch. However, it is not always necessary to synchronize with the horizontal synchronization signal Hsync. Control may be performed so that the average luminance value Yave [7: 0] is transmitted at a timing determined between the LED

display control devices

200a, 200b, 200c, and 200d within the vertical front porch.

(effect)
As described above, in the LED display system 300A according to the second embodiment, the LED

display control devices

200a, 200b, 200c, and 200d are wired OR connected to the other LED

display control devices

200a, 200b, 200c, and 200d. A signal line, and the largest of the average luminance values Y_av_S1, Y_av_S2, Y_av_S3 calculated by the sub-area correction

coefficient calculation units

38, 39, and 40 and the average luminance value Y_av_all calculated by the whole area correction coefficient calculation unit 37 The average luminance value Yave [7: 0] is shared with the other LED

display control devices

200a, 200b, 200c, and 200d via the signal line.

Specifically, a common synchronizing signal is input to each of the LED

display control devices

200a, 200b, 200c, and 200d, and the maximum average luminance value Yave [7: 7] is obtained on the signal line Mul_o [2: 0] that is wired OR connected. 0] can be controlled with the luminance correction coefficient Cy common to the LED

display control devices

200a, 200b, 200c, and 200d. Therefore, power control is different for each of the LED

display control devices

200a, 200b, 200c, and 200d, and the brightness control of the unit LED units 100 connected thereto is dispersed, thereby suppressing the occurrence of a brightness difference in the entire LED display system 300A. it can.

Further, since the average luminance value Yave [7: 0] is divided and transmitted using the signal line Mul_o [2: 0] connected by the wired OR, the LED

display control devices

200a, 200b, and 200c are formed with a small number of signal lines. , 200d can be connected. Further, when the number of bits of the average luminance value Yave is small, the power saving control interval becomes rough. Therefore, when the average luminance value Yave is switched, the luminance of the unit LED unit 100 after the correction greatly changes, so that the flicker of the screen can be visually recognized. However, according to the second embodiment, when the average luminance value Yave is 8 bits, it is possible to perform control in 256 steps, and to suppress flickering of the screen when switching the power saving control.

Transmission of the average luminance value Yave between the LED

display control devices

200a, 200b, 200c, and 200d can be controlled by a microcomputer or other communication means such as a LAN, but the algorithm for synchronizing the average luminance value Yave is complicated. Become. However, when the transmission is performed using the signal line Mul_o [2: 0] that is wired-OR connected as in the second embodiment, the average luminance value Yave can be easily and reliably synchronized.

Although the present invention has been described in detail, the above description is illustrative in all aspects, and the present invention is not limited thereto. It is understood that countless variations that are not illustrated can be envisaged without departing from the scope of the present invention.

It should be noted that the present invention can be freely combined with each other within the scope of the invention, and each embodiment can be appropriately modified or omitted.

1 LED, 5 brightness adjustment section, 6 LED drive section, 34 video signal distribution section, 37 overall area correction coefficient calculation section, 38 first subarea correction coefficient calculation section, 39 second subarea correction coefficient calculation section, 40 third Sub area correction coefficient calculation unit, 41 common correction coefficient calculation unit, 100 unit LED unit, 200, 200a, 200b, 200c, 200d LED display control device, 300, 300A LED display system, 301, 302, 303 power supply device.

Claims

N (n is an integer greater than or equal to 2) sub-display systems each having a plurality of LED display devices (100);
N power supply devices (301, 302, 303) for supplying power to the plurality of LED display devices (100) of each of the sub-display systems;
At least one LED display control device (200, 200a, 200b, 200c, 200d) for distributing a video signal to the plurality of LED display devices (100) included in each of the sub-display systems;
With
At least one of the LED display control devices (200, 200a, 200b, 200c, 200d)
An average luminance value of pixels in a display area formed by each of the sub display systems in the video signal is calculated, and based on the average luminance value, power consumption of each of the sub display systems is equal to or less than a predetermined value. N sub-area correction coefficient calculation units (38, 39, 40) for calculating a luminance correction coefficient for each display area for correcting the luminance of the video signal;
An average luminance value of pixels of one screen in the video signal is calculated, and based on the average luminance value, the video signal so that power consumption of the n sub-display systems as a whole is equal to or less than a predetermined value. An overall area correction coefficient calculation unit (37) for calculating a luminance correction coefficient for the entire one screen for correcting the brightness of
A common correction coefficient calculation unit (41) that calculates a common luminance correction coefficient based on the calculation results of the n sub-area correction coefficient calculation units (38, 39, 40) and the entire area correction coefficient calculation unit (37). )When,
A video signal distribution unit (34) for distributing the video signal and the common luminance correction coefficient to the plurality of LED display devices (100) included in the n sub-display systems;
With
Each of the LED display devices (100)
A plurality of LEDs (1) serving as display pixels;
A luminance adjustment unit (5) for adjusting the luminance of the video signal distributed from the video signal distribution unit based on the common luminance correction coefficient distributed from the video signal distribution unit;
An LED driving unit (6) for driving the plurality of LEDs (1) based on the video signal whose luminance has been adjusted by the luminance adjusting unit (5);
An LED display system comprising:
The common luminance correction coefficient is calculated by the luminance correction coefficient calculated by the n sub area correction coefficient calculation units (38, 39, 40) and the luminance correction calculated by the whole area correction coefficient calculation unit (37). The LED display system according to claim 1, which is a minimum luminance correction coefficient among the coefficients.
At least one of the LED display control devices (200a, 200b, 200c, 200d) includes a plurality of the LED display control devices (200a, 200b, 200c, 200d),
Each of the LED display control devices (200a, 200b, 200c, 200d) further includes a signal line that is wired OR connected to the other LED display control devices (200a, 200b, 200c, 200d), and the n sub-areas Of the average luminance value calculated by the correction coefficient calculation unit (38, 39, 40) and the average luminance value calculated by the overall area correction coefficient calculation unit (37), the maximum average luminance value is determined as the signal line. The LED display system according to claim 1 or 2, which is shared with the other LED display control devices (200a, 200b, 200c, 200d) via a terminal.
An LED display control device provided in the LED display system (300, 300A) according to any one of claims 1 to 3.
An LED display device provided in the LED display system (300, 300A) according to any one of claims 1 to 3.