WO2022003857A1 - Led display device, led display system, and display method of led display device - Google Patents

Abstract

The purpose of the present disclosure is to level the brightness decrease rate between LED elements without excessively decreasing the brightness of an LED display unit. An LED display device (1001) is provided with: an LED display unit (14) that has a plurality of LED elements (102) arranged in a plurality of directions; an LED drive unit (13) that drives the LED elements (102) in accordance with a video signal; a summation unit (15) that calculates accumulated lighting times of the LED elements (102); a brightness decrease detection unit (17) that detects, as an object LED element, an LED element (102) having an accumulated lighting time longer than a first threshold value set with the shortest accumulated lighting time among the accumulated lighting times of the LED elements (102) as a reference; and an offset processing unit (19) that offsets the video signal if the number of the object LED elements is a second threshold value or more.

Description

LED display device, LED display system and display method of LED display device

This disclosure relates to an LED display device, an LED display system, and a display method of the LED display device.

Currently, the brightness, miniaturization, and cost reduction of light emitting diode (LED) elements are progressing. Along with this, LED display devices including LED display units in which a plurality of LED elements are arranged in a plane are widely used for indoor and outdoor advertisement display and the like.

In the past, LED display devices were mainly used to display moving images such as natural images or animations. However, recently, the pixel pitch of the LED display device has become smaller due to the miniaturization of the LED element. As a result, the LED display device has come to be used for applications with a short viewing distance, such as displaying a document image or a surveillance image for a conference indoors. As a result, the LED display device often displays an image close to a still image input from a personal computer or the like.

The cumulative lighting time of each LED element included in the LED display device becomes non-uniform depending on the content of the display image of the LED display device. The brightness of the LED element decreases as the cumulative lighting time increases. Therefore, the brightness reduction rate of each LED element becomes non-uniform depending on the content of the display image of the LED display device. Therefore, as the operating time of the LED display device becomes longer, there is a problem that the brightness and the color of the LED display unit become non-uniform.

In order to solve this problem, the following configurations are proposed in Patent Document 1 and Patent Document 2. The LED display device described in Patent Document 1 calculates the cumulative lighting time of each LED element, corrects the brightness correction coefficient of the LED element whose cumulative lighting time has reached the threshold value, and corrects the display data according to the corrected brightness correction coefficient. Is created and output to the LED display unit. As a result, the brightness unevenness that may occur due to the difference in the cumulative lighting time of the LED elements is suppressed.

The LED display device described in Patent Document 2 raises the duty ratio of the drive signal to the LED element whose cumulative lighting time has reached a preset setting time according to the LED brightness reduction rate calculated based on the cumulative lighting time. .. As a result, the brightness unevenness that may occur due to the difference in the cumulative lighting time of the LED elements is suppressed.

Japanese Unexamined Patent Publication No. 11-15437 Japanese Unexamined Patent Publication No. 2006-330158

The conventional LED display device calculates the brightness reduction rate based on the cumulative lighting time of the LED element, and corrects the brightness based on the brightness reduction rate. Therefore, even if the brightness of the LED element decreases, it is possible to maintain the brightness and color of the image displayed on the LED display unit uniformly.

However, the cumulative lighting time of each LED element is not uniform. In particular, when the LED display unit displays a still image for a long time, the cumulative lighting time of a certain LED element may be significantly longer than that of another LED element, and the brightness may be significantly reduced. Then, in the conventional LED display device, when the LED element whose brightness is greatly reduced is included in the plurality of LED display units, the brightness of the other LED elements is also reduced in accordance with the LED element whose brightness is greatly reduced. There is a problem that the brightness of the LED display unit is excessively lowered.

The technique of the present disclosure has been made to solve the above-mentioned problems, and an object thereof is to level the luminance reduction rate between LED elements without excessively reducing the luminance of the LED display unit. ..

The LED display device of one aspect of the present disclosure includes an LED display unit having a plurality of LED elements arranged in a plurality of directions, an LED drive unit that drives each LED element according to a video signal, and a cumulative total of the LED elements. Brightness reduction that detects as a target LED element an integrating unit that calculates the lighting time and an LED element that has a longer cumulative lighting time than the first threshold determined based on the shortest cumulative lighting time that is the shortest of the cumulative lighting times of each LED element. It includes a detection unit and an offset processing unit that offsets the video signal when the number of target LED elements is equal to or greater than the second threshold value.

According to the LED display device of one aspect of the present disclosure, the video signal is offset when the number of target LED elements is equal to or larger than the second threshold value. Therefore, it is possible to level the brightness reduction rate between the LED elements without excessively reducing the brightness of the LED display unit. The purposes, features, embodiments, and advantages of the present disclosure will be made clearer by the following detailed description and accompanying drawings.

It is a block diagram which shows the structure of the LED display device of Embodiment 1. FIG. It is a perspective view of the LED display part of Embodiment 1. FIG. It is a top view which shows the structure of one LED. It is a figure explaining the waveform of the PWM drive signal of the LED element. It is a perspective view of the LED display device of Embodiment 1. FIG. It is a perspective view which shows the arrangement example of the pixel in the partial area of the LED display part of Embodiment 1. FIG. It is a flowchart which shows the luminance correction operation of the LED display device of Embodiment 1. FIG. It is a figure which shows the basic example of the offset processing of the video signal in the partial area of the LED display part of Embodiment 1. FIG. It is a flowchart which shows the offset process of the LED display device of Embodiment 1. It is a figure which shows the basic example of the offset processing of the video signal in the partial area of the LED display part of Embodiment 2. It is a block diagram which shows the structure of the LED display device of Embodiment 3. It is a figure which shows the relationship between the lighting time of the LED element, and the brightness reduction rate. It is a flowchart which shows the luminance correction operation of the LED display device of Embodiment 3. It is a block diagram of the LED display system of Embodiment 4. FIG. It is a figure which shows the connection relation of each component of the LED display system of Embodiment 4. It is a block diagram which shows the structure of the image control apparatus of Embodiment 4. FIG. It is a block diagram which shows the structure of the LED display device of Embodiment 4. It is a flowchart which shows the offset process of the LED display system of Embodiment 4. It is a figure which shows the hardware composition of the LED display device and the like. It is a figure which shows the hardware composition of the LED display device and the like.

<A. Embodiment 1>
<A-1. Configuration>
FIG. 1 is a block diagram showing a configuration of the LED display device 1001 according to the first embodiment. As shown in FIG. 1, the LED display device 1001 includes an input terminal 11, a signal processing unit 12, an LED drive unit 13, an LED display unit 14, an integrating unit 15, a lighting time storage unit 16, a brightness reduction detection unit 17, and a correction amount. It includes a calculation unit 18 and an offset processing unit 19.

FIG. 2 is a perspective view of the LED display unit 14. As shown in FIG. 2, the LED display unit 14 includes a plurality of LEDs 101 arranged in a matrix. In FIG. 2, 16 LEDs 101 are arranged in 4 in the vertical direction and 4 in the horizontal direction, but the number and arrangement mode of the LEDs 101 in the LED display unit 14 are not limited to those shown in FIG.

FIG. 3 is a plan view of the LED 101. As shown in FIG. 3, the LED 101 includes LED elements 102r, 102g, 102b. One LED 101 constitutes one pixel. The LED element 102r emits red light, the LED element 102g emits green light, and the LED element 102b emits blue light. As described above, the r, g, and b attached to the end of the reference numerals of the LED elements 102r, 102g, 102b represent the emission colors of the LED elements 102r, 102g, 102b. In the following description, when the LED element is referred to without being limited to a specific emission color, it is simply referred to as the LED element 102. Further, the LED element 102 included in the LED display unit 14 is also referred to as a first LED element.

A video signal is input to the input terminal 11 from a video signal source such as a video information processing device. The video information processing device is, for example, a personal computer.

The signal processing unit 12 performs various image quality correction processing such as gamma correction on the video signal input from the input terminal 11.

The offset processing unit 19 performs offset processing on the video signal that has undergone various image quality correction processing by the signal processing unit 12. The offset processing unit 19 performs offset processing according to the offset correction amount calculated by the correction amount calculation unit 18. The offset processing includes a process of enlarging or reducing the video signal, a process of selecting an area to be displayed on the LED display unit 14 from the enlarged or reduced video signal, and a display position of the LED display unit 14 for displaying the video signal. That is, a process of designating the LED 101, which is a pixel for displaying a video signal, is included.

For example, the offset processing unit 19 enlarges the video signal by 105% and selects an area necessary for displaying a desired video from the enlarged video signal. Then, the offset processing unit 19 performs a process of shifting the display position of the image in the LED display unit 14 within a range of, for example, 5%, and displays the image on the LED element 102 arranged in the LED 101 at the designated position. Even if the image is shifted in this way, the area where the image is not displayed on the top, bottom, left, and right of the image does not appear on the LED display unit 14. When the image signal is reduced, the offset processing unit 19 may supplement the surroundings with, for example, a black image in order to reduce the sense of discomfort in the surroundings of the image. Further, the offset processing unit 19 may rotate the image depending on the content of the image.

The LED drive unit 13 drives a plurality of LEDs 101 of the LED display unit 14 according to the video signal offset processed by the offset processing unit 19. The blinking and luminance of each LED element 102 arranged in each LED 101 is controlled by a pulse width modulation (PWM) method. The LED drive unit 13 supplies a drive signal having a duty ratio proportional to the signal level of each LED element 102 to each LED element 102. Each LED element 102 is turned on during the on period of the supplied drive signal, so that the LED element 102 is turned on with a brightness proportional to the signal level.

FIG. 4 is a timing chart for explaining the waveform of the PWM drive signal of each LED element 102. In FIG. 4, the waveform W1 is a waveform of a signal including a pulse repeatedly generated in the basic cycle of PWM drive. The waveform W2 is a waveform of a drive signal having a duty ratio of 85%. The waveform W3 is a waveform of a drive signal having a duty ratio of 80%.

The basic period of PWM drive indicated by the waveform W1 is one frame period or less of the video signal. The drive signal of the waveform W2 includes a pulse that is repeatedly emitted in the basic cycle of PWM drive and has a pulse width PW1 of 85% of the basic cycle of PWM drive. The drive signal of the waveform W3 is repeatedly generated in the basic cycle of PWM drive, and includes a pulse having a pulse width PW2 of 80% of the basic cycle of PWM drive. The brightness of the LED element 102 to which the drive signal of the waveform W2 is supplied is different from that of the LED element 102 to which the drive signal of the waveform W3 is supplied. Therefore, the LED drive unit 13 adjusts the brightness of each LED element 102 by changing the duty ratio of the drive signal supplied to each LED element 102.

The integration unit 15 performs an integration process of the lighting time of each LED element 102 to calculate the cumulative lighting time of each LED element 102. The lighting time storage unit 16 stores the cumulative lighting time of each LED element 102 calculated by the integration unit 15.

When the brightness of each LED element 102 changes at the highest speed, it changes for each frame of the displayed image. Therefore, the following method is assumed as a method for accurately calculating the cumulative lighting time of each LED element 102.

That is, the integration unit 15 performs integration processing of the lighting time of each LED element 102 every time the basic cycle of PWM drive ends. In the integration process, the integration unit 15 integrates the product of the length of the basic cycle of PWM drive and the drive coefficient indicating the ratio of the lighting time of each LED element 102 to the length of the basic cycle of PWM drive. The cumulative lighting time of the LED element 102 can be calculated accurately. As the drive coefficient of each LED element 102, the duty ratio of the drive signal supplied to each LED element 102 can be used. However, if the above integration processing is performed for each LED element 102 each time the basic period of PWM drive is completed, the arithmetic processing becomes enormous and the writing of data to the non-volatile memory becomes high frequency. Therefore, in the LED display device 1001 of the first embodiment, the integration unit 15 calculates the cumulative lighting time of each LED element 102 by the method described later in order to efficiently perform the integration process.

The integrating unit 15 performs an integration process of the lighting time of each LED element 102 every time a preset time (hereinafter referred to as “set time”) elapses, and calculates the cumulative lighting time of each LED element 102. .. The set time may be constant or variable, but is longer than the length of the basic period of PWM drive.

In the integration process, the integration unit 15 stores the cumulative operating time t ₁ of the LED display unit 14 in the lighting time storage unit 16. Further, the integration unit 15, in the integration process, the average drive coefficient _{R 2} of the LED elements 102 that indicates the ratio of the cumulative lighting time _{S 1} of the LED elements 102 for the cumulative operating time _{t 1} from the driving condition of the LED elements 102 calculated, and stores the calculated average drive coefficient R ₂ to the lighting time storage unit 16. Therefore, the lighting time storage unit 16 stores the cumulative operating time t ₁ and the average drive coefficient R ₂ . In the first embodiment, the average drive coefficient R ₂ is the average duty ratio of the drive signals supplied to each LED element 102 until the integration process is performed. As a result, the integration unit 15 updates the cumulative lighting time information including _{the cumulative operating time t 1} and the average drive coefficient R ₂ stored in the lighting time storage unit 16 every time the set time elapses. The integrating unit 15 updates the cumulative lighting time information of all the pixels, that is, the cumulative lighting time information of each LED element 102 of all the LEDs 101 at once.

Further, the integration unit 15, the driving conditions of the LED elements 102 for performing the integration process, the driving factor _{R 1} of the LED elements 102 that indicates the ratio of the lighting time of the LED elements 102 for operating time of the LED display section 14 Is calculated.

Further, the integration unit 15 sets the cumulative operating time t ₁ of the LED display unit 14 stored in the lighting time storage unit 16 in the previous integration process as the previous cumulative operation time t _{0, and sets the lighting time storage unit 16 in the previous integration process. The average drive coefficient R 2} of each LED element 102 stored in is set to the previous average drive coefficient R ₀ . Then, the integration unit 15 sets the previous cumulative operating time t ₀ , the previous average drive coefficient R _{0 , the elapsed time t 1 −} t ₀ from the previous integration process to the integration process, and the calculated drive coefficient R ₁ of each LED element 102. based on, to calculate the cumulative lighting time _{S 1} of the LED elements 102. In the first embodiment, the drive coefficient R ₁ is the duty ratio of the drive signal supplied to each LED element 102 when the previous integration process is performed. Further, in the first embodiment, the previous average drive coefficient R ₀ is the average duty ratio of the drive signals supplied to each LED element 102 until the previous integration process is performed.

As shown in the equation (1), _{the cumulative lighting time S 0} of each LED element 102 when the previous integration process is performed is _{the previous cumulative operating time t 0} of the LED display unit 14 and the previous average of each LED element 102. It is represented by the product of the drive coefficient R _0.

The integration unit 15 was supplied to the drive coefficient of each LED element 102, that is, to each LED element 102 in the entire basic cycle of PWM drive that arrived between the time when the integration process was performed last time and the time when the integration process was performed this time. It is assumed that _{the duty ratio of the drive signal is R 1} , which is the duty ratio of the drive signal supplied to each LED element 102 when the previous integration process is performed. _{Therefore, the cumulative lighting time S 1} of each LED element 102 when the integration process is performed is _{the cumulative lighting time S 0} , the elapsed time t _{1 −} t _0, and the drive coefficient R ₁ as shown in the equation (2). It is expressed by the product of and the sum of.

Average drive coefficient _{R 2} of the LED elements 102 is obtained by dividing, as shown in equation (3), the cumulative lighting time _{S 1} of the LED elements 102 with the cumulative operating time _{t 1} of the LED display section 14 It is a coefficient. Therefore, when the equation (1) and the equation (2) are taken into consideration, the average drive coefficient R _{2 is the previous cumulative operating time t 0} of the LED display unit 14 and the previous time of each LED element 102, as shown in the equation (3). and the product of the average driving coefficient _{R 0,} the elapsed time _t 1 -t ₀ and the product of the driving factor _{R 1} of the LED elements 102, the sum of, obtained by dividing the cumulative operation time t1.

Integrating unit 15, every time the cumulative operating time t ₁ of the LED display unit 14 for the set time elapses from the time point of 0, calculates an average driving factor R _2, previous average drive coefficients stored in the lighting time storage unit 16 R ₀ is updated with the average drive coefficient R _2.

When the change in the display pattern displayed on the LED display unit 14 is small, the change in the luminance of each LED element 102 is also small, and the change in the duty ratio of the drive signal supplied to each LED element 102 is also small. Therefore, in this case, be sufficiently longer than the fundamental period of the time setting the PWM drive, the actual lighting time of the LED elements 102, accumulation of the LED elements 102 that integrating unit 15 calculates the average driving factor R ₂ The difference between the lighting time S _{1 and the lighting time S 1 is sufficiently small.} That is, the integrated unit 15 can be accurately calculated from the average driving factor _{R 2} of the cumulative lighting time _{S 1} of the LED elements 102.

Cumulative lighting time _{S 1} of the LED elements 102 that integrating unit 15 has been calculated is used later to luminance correction. Thus, the integrated unit 15, the cumulative lighting time S ₁ of the LED elements 102 while reducing the amount of arithmetic processing for accumulation process can be accurately calculated.

Luminance drop detection unit 17, from the cumulative lighting time S ₁ of the LED elements 102 stored in the lighting time storage unit 16, extracts the shortest cumulative lighting time S _{1 (hereinafter,} referred to as the shortest cumulative lighting time). Then, the brightness reduction detection unit 17 sets a threshold value (first threshold value) for the cumulative lighting time based on the shortest cumulative lighting time, and counts the number of LED elements 102 whose cumulative lighting time is equal to or longer than the threshold value.

The LED element 102 has a characteristic that the brightness decreases with the lighting time. Based on this characteristic, the brightness reduction detection unit 17 considers that the LED element 102 having a longer lighting time has a lower brightness. Then, the brightness reduction detection unit 17 compares the degree of brightness reduction of each LED element 102 by the ratio of the lighting time of each LED element 102. That is, the brightness of the LED element 102 is expressed as a function of the lighting time of the LED element 102, and has a characteristic that it decreases as the lighting time becomes longer.

<A-2. Operation>
FIG. 5 is a perspective view of the LED display device 1001. In FIG. 5, the LED display device 1001 includes four LED display units 14a, 14b, 14c, 14d arranged in a vertical direction 2 × horizontal direction 2, and has a pixel resolution of 320 × 360. In FIG. 5, the LED display units 14a, 14b, 14c, and 14d have the same configuration as the LED display unit 14, but the characters ad are added to the end of the reference numerals to distinguish them from each other.

FIG. 6 is a perspective view showing an example of arrangement of the LED 101 in the partial region 101a constituting a part of the display surface of the LED display unit 14a. In the partial region 101a, 16 LEDs 101 are arranged in a length of 4 × a width of 4.

FIG. 7 is a flowchart showing the overall operation of the LED display device 1001. Hereinafter, the operation of the LED display device 1001 will be described according to the flow of FIG. 7.

First, the integration unit 15 determines whether or not a predetermined set time has elapsed since the previous integration process (step S101). The set time is a unit time of luminance correction, and is, for example, 100 hours. The integration unit 15 repeats the process of step S101 until the set time elapses from the previous integration process. Integrating unit 15 determines that the set time has elapsed from the previous integration processing (Yes at step S101), LED elements 102r, 102 g, by integrating the 102b lighting time of calculating the accumulated lighting time _{S 1,} the lighting time storage It is stored in the unit 16 (step S102). Hereinafter, LED element 102r, 102 g, the cumulative lighting time _{S 1} of 102b tr, tg, is denoted as tb.

Next, the brightness reduction detection unit 17 determines the shortest cumulative lighting time tr, tg, tb among the cumulative lighting times tr, tg, tb of the LED elements 102r, 102g, 102b stored in the lighting time storage unit 16. Extraction is performed as the shortest cumulative lighting time tr _min , tg _min , and tb _{min (step S103).} The luminance drop detection unit 17, the following equation (4), by (5), (6), to calculate the threshold TRth the cumulative lighting time _{S 1,} TGth, the TBTH. Here, Th is a constant greater than 1. Further, the threshold values TRth, TGth, and TBth of the cumulative lighting time S _{1 are also referred to as a first threshold value.}

Next, the brightness reduction detection unit 17 determines whether or not there is at least one LED element 102 whose cumulative lighting time tr, tg, and tb exceeds the threshold values TRth, TGth, and TBth (step S104). If there is no LED element 102r whose cumulative lighting time tr exceeds the threshold TRth, an LED element 102g whose cumulative lighting time tg exceeds the threshold TGth, or an LED element 102b whose cumulative lighting time tb exceeds the threshold TBth, the LED display device 1001 steps again. The process of S101 is performed.

When the brightness reduction detection unit 17 determines that there is at least one LED element 102 whose cumulative lighting times tr, tg, and tb exceed the threshold values TRth, TGth, and TBth, the process of the LED display device 1001 proceeds to step S105.

In step S104, the brightness reduction detection unit 17 counts the number of LED elements 102 whose cumulative lighting time tr, tg, and tb exceeds the threshold values TRth, TGth, and TBth, and sets a second threshold value for which the number is predetermined. If it exceeds the limit, the process of the LED display device 1001 may proceed to step S105. Further, the LED element 102 in which the cumulative lighting time tr, tg, and tb exceeds the threshold values TRth, TGth, and TBth is also referred to as a target LED element.

In step S105, the correction amount calculation unit 18 calculates the offset amount with respect to the drawing start position of the input video signal, and the offset processing unit 19 performs the offset processing. The relative positions of the image and the plurality of LEDs 101 are displaced based on the offset amount. As a result, the duty ratio of the LED element 102 determined in step S104 that the cumulative lighting time exceeds the threshold value is lowered, and the decrease in brightness is suppressed. Further, the duty ratio of the LED element 102 determined in step S104 that the cumulative lighting time is equal to or less than the threshold value increases, and the brightness further decreases. As a result, the degree of brightness reduction is leveled among the LEDs 101. The visual effect of offset processing also depends on the video content. In content such as a system diagram represented by a one-dot line displayed for general monitoring applications, the visual effect due to the leveling of luminance is higher.

After step S105, the LED display device 1001 determines whether or not the video display is completed (step S106). If Yes in step S106, the series of offset processing ends. When the video display is continued (No in step S106), the process of the LED display device 1001 returns to step S101.

FIG. 8 shows a basic example of offset processing of a video signal in the partial region 101a of the LED display unit 14a. S0 in FIG. 8 shows a partial region 101a in a non-lighting state. From this state, when the area 101 becomes the lighting state 1 (S1), the LED elements 102 of the two LED 101s in the center are turned on. When the lighting state 1 (S1) elapses for a long time, the brightness of the LED element 102 of the two LEDs 101 that have been lit decreases.

The offset processing unit 19 shifts the video signal and performs offset processing as in the lighting state 2 (S2) in order to level the decrease rate of the brightness of the LED element 102. In the lighting state 2 (S2), the position of the image displayed by the image signal is shifted upward by one pixel. The offset processing performed by the offset processing unit 19 is not limited to that shown in FIG. The position of the image displayed by the image signal may be moved in either the up, down, left, or right direction in the offset processing, or may be moved in any other direction. Further, the offset processing unit 19 may enlarge or reduce the image, move the image as described above and then enlarge or reduce the image, or rotate the image.

<A-3. Effect>
The LED display device 1001 of the first embodiment has an LED display unit 14 having a plurality of LED elements 102 arranged in a plurality of directions, an LED drive unit 13 for driving each LED element according to a video signal, and each LED element. The target LED is the integrating unit 15 that calculates the cumulative lighting time of the 102, and the LED element 102 whose cumulative lighting time is longer than the first threshold determined based on the shortest cumulative lighting time of the cumulative lighting time of each LED element 102. It includes a brightness reduction detection unit 17 that detects as an element, and an offset processing unit 19 that offsets a video signal when the number of target LED elements is equal to or greater than the second threshold value. Therefore, the brightness reduction rate of each LED element 102 is leveled without excessively darkening the entire LED display unit 14. As a result, the uniformity of brightness and the white balance are maintained in the LED display unit 14.

Most of the surveillance images are still images. Therefore, when the LED display device 1001 displays the surveillance image, usually only a part of the LED elements 102 included in the plurality of LEDs 101 emit light for a long time. Therefore, the brightness of the LED element 102 that emits light for a long time is significantly lower than the brightness of the other LED elements 102. In such a case, according to the conventional luminance control that maintains the uniformity of the luminance of all of the plurality of LEDs 101, the luminance of all of the plurality of LEDs 101 is greatly reduced in accordance with the significantly reduced luminance of the LED element 102. .. On the other hand, according to the LED display device 1001 of the first embodiment, when the LED elements 102r, 102g, 102b whose cumulative lighting time tr, tg, tb is longer than the thresholds TRth, TGth, TBth are present, the video signal is present. By applying an offset process to the LED element 102, which emits strong light, the LED element 102 is shifted. As a result, the degree of brightness reduction is leveled among the plurality of LEDs 101, so that the overall brightness of the LED display unit 14 does not excessively decrease due to the brightness reduction of the specific LED element 102.

It is possible to perform offset processing at a predetermined fixed cycle, but if the cycle is short, it gives the user a sense of discomfort. However, in the LED display device 1001 of the first embodiment, since the offset processing is performed only when the difference in luminance decrease between the LED elements 102 becomes large, unnecessary offset adjustment is not performed, which gives a user a sense of discomfort. There is no.

<B. Embodiment 2>
In the first embodiment, the basic offset processing has been described. In the offset process, the LED display device 1002 of the second embodiment determines the direction and order of shifting the image based on the degree of decrease in the brightness of each LED element 102. The configuration of the LED display device 1002 is the same as the configuration of the LED display device 1001 of the first embodiment shown in FIG.

<B-1. Operation>
FIG. 9 is a flowchart showing the offset processing of the LED display device 1002. The flow of the overall operation of the LED display device 1002 is as shown in FIG. 7, and FIG. 9 corresponds to the detailed flowchart of step S105 in FIG.

FIG. 10 is a diagram showing a basic example of offset processing of a video signal in the partial region 101a of the LED display unit 14a of the LED display device 1002. S0 in FIG. 10 shows a partial region 101a in a non-lighting state. From this state, when the area 101 becomes the lighting state 1 (S21), the LED elements 102 of the two LED 101s in the center are lit. When the lighting state 1 (S1) elapses for a long time, the brightness of the LED element 102 of the two LEDs 101 that have been lit decreases. Therefore, the LED display device 1002 executes the offset processing shown in FIG.

Hereinafter, the offset processing of the LED display device 1002 will be described according to the flow of FIG. First, the correction amount calculation unit 18 calculates the difference in cumulative lighting time between each LED element 102 constituting each LED 101 and the other LED elements 102 adjacent in all directions (step S201). Here, the omnidirectional directions are the four directions indicated by the arrows (1), (2), (3), and (4) in the example of FIG.

For example, in the lighting state 1 (S21) of FIG. 10, the cumulative lighting time of the LED element 102 included in the LED 101 being lit is the cumulative lighting time of the LED element 102 included in the LED 101 in which the LED 101 is adjacent to the direction (1). Longer. The correction amount calculation unit 18 calculates the cumulative lighting time difference between these two adjacent LED elements 102 for all the LED elements 102 and all the adjacent directions.

Next, the correction amount calculation unit 18 adds up the cumulative lighting time difference of each LED element 102 for each direction (step S202).

Next, the correction amount calculation unit 18 selects the direction in which the sum of the cumulative lighting time differences of the LED elements 102 is maximum as the offset direction (step S205). In this way, the correction amount calculation unit 18 operates as an offset direction determination unit.

For example, if the direction (1) is selected as the offset direction, the offset processing unit 19 shifts the image in the direction (1) as shown in the lighting state 2 (S22) in FIG. 10 (step S206). The direction adjacent to the LED element 102 in which the offset processing unit 19 calculates the cumulative lighting time difference is not limited to the directions (1), (2), (3), and (4) shown in FIG. For example, the offset processing unit 19 may calculate the cumulative lighting time difference between the LED elements 102 adjacent in the diagonal direction. Further, the offset processing unit 19 may enlarge or reduce the image, move the image as described above and then enlarge or reduce the image, or rotate the image. The offset processing unit 19 may schedule the order of movement.

<B-2. Effect>
The LED display device 1002 of the second embodiment calculates the sum of the cumulative lighting time differences of the plurality of adjacent LED elements 102 in each direction of the plurality of directions in which the plurality of LED elements are arranged, and the sum of the cumulative lighting time differences is calculated. A correction amount calculation unit 18 which is an offset direction determination unit whose maximum direction is the offset direction is provided. Then, the offset processing unit 19 offsets the video signal in the offset direction. As a result, the image display is shifted from the LED element 102 having a large brightness reduction rate to the LED element 102 having a small brightness reduction rate due to the offset, so that the brightness reduction between the LED elements 102 is efficiently leveled.

<C. Embodiment 3>
In the LED display devices 1001 and 1002 of the first and second embodiments, the degree of decrease in brightness between the LED elements 102 is compared based on the cumulative lighting time of the LED elements 102, and offset processing is performed. In the LED display device 1003 of the third embodiment, the brightness reduction rate of each LED element 102 is measured, and the degree of brightness reduction between the LED elements 102 is precisely determined based on the cumulative lighting time and the brightness reduction rate of each LED element 102. Compared to, offset processing is performed.

<C-1. Configuration>
FIG. 11 is a block diagram of the LED display device 1003 according to the third embodiment. In FIG. 11, the LED display device 1003 includes an input terminal 11, a signal processing unit 12, a correction amount calculation unit 18, an offset processing unit 19, a first LED drive unit 21, a first LED display unit 22, a second LED drive unit 23, and a second LED. It includes a display unit 24, a brightness measurement unit 25, a brightness reduction rate storage unit 26, an integration unit 27, a lighting time storage unit 28, a brightness reduction detection unit 29, a correction coefficient calculation unit 30, and a brightness correction unit 31.

The first LED drive unit 21 and the first LED display unit 22 correspond to the LED drive unit 13 and the LED display unit 14 in the LED display devices 1001 and 1002. Further, the input terminal 11, the signal processing unit 12, the correction amount calculation unit 18, and the offset processing unit 19 in the LED display device 1003 are the input terminal 11, the signal processing unit 12, the correction amount calculation unit 18 and the LED display devices 1001 and 1002. It has the same configuration as the offset processing unit 19. Therefore, the description of these configurations will be omitted.

The second LED display unit 24 displays for measuring (predicting) the transition of the brightness of the first LED display unit 22. The second LED display unit 24 has the same configuration as the first LED display unit 22, and has a plurality of LEDs 101. Each LED 101 includes a plurality of LED elements 102r, 102g, 102b. Each LED element 102 included in the first LED display unit 22 and each LED element 102 included in the second LED display unit 24 are, for example, LED elements of the same type and have the same luminance reduction characteristics. Hereinafter, in order to distinguish between the two, the former is also referred to as a first LED element, and the latter is also referred to as a second LED element. The second LED drive unit 23 drives each LED 101 of the second LED display unit 24, and controls the lighting of each LED element 102 constituting each LED 101.

The brightness measuring unit 25 is arranged to face the second LED display unit 24, and measures the brightness of each LED element 102 of the second LED display unit 24. The change in luminance is, for example, the luminance maintenance rate indicating the current luminance with the initial luminance as 100%, or the luminance reduction rate (= 100% -luminance retention rate) which is the opposite relationship to the luminance retention rate. And so on. In the following, it is assumed that the decrease rate of the luminance is applied to the transition of the luminance.

The brightness reduction rate storage unit 26 stores a table (hereinafter, also referred to as “brightness reduction rate information”) showing the relationship between the lighting time and the brightness reduction rate of the LED elements 102r, 102g, 102b of the second LED display unit 24. ..

The integrating unit 27 performs an integration process of the lighting time of each LED element 102 of the first LED display unit 22 and the second LED display unit 24, and the cumulative lighting of each LED element 102 of the first LED display unit 22 and the second LED display unit 24 is performed. Calculate the time. The lighting time storage unit 28 stores the cumulative lighting time of each LED element 102 of the first LED display unit 22 and the second LED display unit 24.

The second LED display unit 24 is based on the cumulative lighting time of each LED element 102 of the second LED display unit 24 calculated by the integration unit 27 and the brightness of each LED element 102 of the second LED display unit 24 measured by the brightness measurement unit 25. A table showing the relationship between the cumulative lighting time and the brightness reduction rate of each of the LED elements 102 of the above is obtained.

The brightness reduction detection unit 29 has the cumulative lighting time of the first LED display unit 22 stored in the lighting time storage unit 28 and the lighting time of each LED element 102 of the second LED display unit 24 stored in the brightness reduction rate storage unit 26. The brightness reduction rate of each LED element 102 of the first LED display unit 22 is obtained from the relationship between the brightness reduction rate and the brightness reduction rate. Further, the brightness reduction detection unit 29 determines the brightness reduction rate based on the smallest brightness reduction rate (hereinafter referred to as “minimum brightness reduction rate”) among the brightness reduction rates of each LED element 102 of the first LED display unit 22. Set a threshold. Then, the brightness reduction detection unit 29 counts the number of LED elements 102 of the first LED display unit 22 whose brightness reduction rate is equal to or higher than the threshold value.

FIG. 12 shows the relationship between the lighting time of the LED element 102 and the brightness reduction rate. With reference to FIG. 12, the relationship between the lighting time of the LED element 102 and the brightness reduction rate will be described. The brightness of the LED elements 102r, 102g, 102b is a function of the lighting time t of the LED elements 102r, 102g, 102b, and decreases as the lighting time t becomes longer. Therefore, the brightness reduction rate kr (t) of the LED element 102r is a function of the lighting time t of the LED elements 102r, 102g, and 102b, respectively, and increases as the lighting time t increases.

The brightness reduction rate is usually obtained by prior measurement. However, the LED display device 1003 of the third embodiment incorporates the second LED drive unit 23, the second LED display unit 24, and the brightness measurement unit 25 described above. Then, the brightness reduction rate of each LED element 102 of the second LED display unit 24 is measured by the second LED drive unit 23, the second LED display unit 24, and the brightness measurement unit 25 incorporated in the LED display device 1003. The relationship between the measured brightness reduction rate of each LED element 102 of the second LED display unit 24 and the lighting time is stored in the brightness reduction rate storage unit 26. In this way, the LED display device 1003 can measure the relationship between the lighting time of each LED element 102 of the second LED display unit 24 and the brightness reduction rate in real time.

<C-2. Operation>
FIG. 13 is a flowchart of the brightness correction operation of the LED display device 1003. The luminance correction operation of the LED display device 1003 will be described along with the flow of FIG.

Step S301 is the same as step S101 of FIG. 7 described in the first embodiment. After the set time has elapsed from the previous integration process, the integration unit 27 calculates the cumulative lighting time of each LED element 102 of the first LED display unit 22 and the second LED display unit 24 and stores it in the lighting time storage unit 28 (step S302). ).

Next, the brightness reduction detection unit 29 displays the cumulative lighting time of each LED element 102 of the first LED display unit 22 stored in the lighting time storage unit 28 and the second LED display stored in the brightness reduction rate storage unit 26. With reference to a table showing the relationship between the brightness reduction rate of each LED element 102 of the unit 24 and the lighting time for each emission color, the brightness reduction rate kr (t) of each LED element 102r, 102g, 102b of the first LED display unit 22. , Kg (t), kb (t) are calculated (step S303).

Then, the brightness reduction detection unit 29 sets the lowest brightness reduction rate kr (t) of the brightness reduction rate kr (t) of the LED element 102r of the first LED display unit 22 calculated in step S303 to the minimum brightness reduction rate kr ( t) Extract as _{min. Similarly, the brightness reduction detection unit 29 extracts the minimum brightness reduction rate kg (t) min} and kb (t) _min for the LED elements 102g and 102b of the first LED display unit 22 (step S304).

Further, the luminance reduction detection unit 29 calculates the thresholds YRth, YGth, and YBth of the luminance reduction rate by the following equations (7), (8), and (9). Here, Thb is a constant larger than 1. The threshold values of the brightness reduction rate, YRth, YGth, and YBth, are also referred to as a third threshold value.

Next, the brightness reduction detection unit 29 determines whether or not there is at least one LED element 102 whose brightness reduction rate exceeds the threshold value (step S305). When the brightness reduction detection unit 29 determines that there is at least one LED element 102 (hereinafter, also referred to as a target LED element) whose brightness reduction rate exceeds the threshold value, the LED display device 1003 executes the offset process in step S306, and then performs the offset processing. , The luminance correction process of step S307 is executed. The offset processing in step S306 is the same as in steps S105 of FIG. 7 described in the first embodiment or steps S201 to S204 of FIG. 9 described in the second embodiment. There must be an LED element 102r whose brightness reduction rate kr (t) exceeds the threshold value YRth, an LED element 102g whose brightness reduction rate kg (t) exceeds the threshold value YRth, or an LED element 102b whose brightness reduction rate kb (t) exceeds the threshold value YRth. For example, the LED display device 1003 executes the luminance correction process of step S307 without performing the offset process. As described above, the LED display device 1003 of the third embodiment determines whether or not the offset processing needs to be executed based on the brightness reduction rate, not the cumulative lighting time.

In step S307, the luminance correction unit 31 performs the luminance correction.

In step S305, the brightness reduction detection unit 29 counts the number of LED elements 102 whose brightness reduction rates kr (t), kg (t), and kb (t) exceed the threshold values YRth, YGth, and YBth, and the number thereof. When is equal to or higher than a predetermined fourth threshold value, the process of the LED display device 1003 may proceed to step S106.

After step S307, the LED display device 1003 determines whether or not the video display is completed (step S308). If Yes in step S308, the series of luminance correction processes ends. When the video display is continued (No in step S308), the process of the LED display device 1003 returns to step S301.

It should be noted that the third embodiment can be combined with the second embodiment. That is, in the offset processing in step S306, the correction amount calculation unit 18 calculates the difference in brightness reduction rate between the adjacent LED elements 102 for each LED element 102, adds up the difference in brightness reduction rate for each adjacent direction, and reduces the brightness. The direction in which the sum of the rate differences is maximum may be the offset direction.

<C-3. Effect>
The LED display device 1003 of the third embodiment includes a first LED display unit 22 having a plurality of first LED elements arranged in a plurality of directions, a first LED drive unit 21 for driving each first LED element according to a video signal, and the like. The brightness reduction rate storage unit 26 for storing the brightness reduction rate information indicating the relationship between the lighting time and the brightness reduction rate of the second LED element having the same brightness reduction characteristic as the first LED element, and the cumulative lighting time of each first LED element. Based on the integrated unit 27 to be calculated, the cumulative lighting time of each first LED element, and the brightness reduction rate information of the second LED element, the brightness reduction rate of each first LED element is calculated, and the brightness reduction rate of each second LED element is calculated. Among them, the brightness reduction detection unit 29 that detects the first LED element whose brightness reduction rate is larger than the third threshold determined based on the minimum minimum brightness reduction rate as the target LED element, and the number of target LED elements is the fourth threshold or more. In some cases, an offset processing unit 19 for offsetting the video signal is provided.

The LED display device 1003 of the third embodiment is based on the number of LED elements 102 of the first LED drive unit 21 in which the luminance reduction rates kr (t), kg (t), and kb (t) are larger than the threshold values YRth, YGth, and YBth. , Offset processing is performed, and the display position of the image is shifted and displayed. As a result, the brightness reduction rate is leveled between the LED elements 102 of the first LED drive unit 21. As a result, the uniformity of brightness and the white balance can be maintained in the first LED display unit 22 without excessively darkening the entire first LED display unit 22.

In the LED display device 1003 of the third embodiment, the brightness reduction rate of each LED element 102 is accurately measured, and the offset processing is performed only when the difference in brightness reduction between the LED elements 102 becomes large, so that it is frequent. Offset adjustment is not performed, and the user does not feel uncomfortable.

The LED display device 1003 of the third embodiment acquires the brightness reduction rate of each LED element 102 from the measurement result of the brightness of the second LED display unit 24 by the brightness measuring unit 25. However, when the LED display device 1003 is shipped from the factory, the relationship between the lighting time measured using the LED having average characteristics and the brightness reduction rate is stored in the brightness reduction rate storage unit 26 and stored. The brightness reduction detection unit 29 may refer to the relationship between the lighting time and the brightness reduction rate and the measurement result of the brightness measurement unit 25 to detect the brightness reduction of the LED element 102. In this case, an abnormal measured value due to a sudden failure of the LED or the like is not subject to correction.

The LED display device 1003 performed offset processing and brightness correction of each LED element in order to level the brightness reduction rate between the LED elements, suppress uneven brightness, and maintain good image display quality. However, when the displayed image is relatively moving, the LED display device 1003 may perform only offset processing. Since the luminance correction of each LED element 102 requires a processing load according to the number of display pixels, the processing load of the arithmetic unit can be reduced by performing only the offset processing.

<D. Embodiment 4>
In the first, second, and third embodiments, one LED display device 1001, 1002, 1003 has been described. In the fourth embodiment, an LED display system in which a large screen is configured by a plurality of LED display devices arranged in a matrix will be described.

<D-1. Configuration>
FIG. 14 is a configuration diagram of the LED display system 400 of the fourth embodiment. The LED display system 400 includes a plurality of LED display devices 1004 arranged in a matrix and a video control device 5. In FIG. 14, 18 LED display devices 1004 are arranged vertically with 3 units and 6 units in the horizontal direction to form a large screen. In order to distinguish the 18 LED display devices 1004, the letters ar are added to the end of the reference code, and the term is referred to as the LED display device 1004a-1004r.

The LED display device 1004a-1004r is connected to the video control device 5 by a cable 60.

FIG. 15 shows the connection relationship of each component of the LED display system 400. The video control device 5 and the LED display device 1004a-1004r are connected by a video cable 60a such as DVI (Digital Visual Interface) and a communication cable 60b such as LAN (Local Area Network).

FIG. 16 is a block diagram of the video control device 5. In FIG. 16, the video control device 5 includes an input terminal 51, a generation unit 52, an output unit 53, an output terminal 54, a communication terminal 55, a communication unit 56, a storage unit 57, and a brightness reduction detection unit 58.

The generation unit 52 performs signal processing for displaying the video signal input from the input terminal 51 on the LED display device 1004a-1004r. The output unit 53 processes the video signal processed by the generation unit 52 into a video signal to be displayed on each LED display device 1004a-1004r, and outputs the video signal from the output terminal 54 to each LED display device 1004a-1004r.

The communication unit 56 transmits / receives information to / from each LED display device 1004a-1004r. The storage unit 57 stores the lighting time and the brightness reduction rate of each LED display device 1004a-1004r. The brightness reduction detection unit 58 detects the LED element 102 whose brightness has decreased in each LED display device 1004a-1004r.

FIG. 17 is a block diagram showing the configuration of the LED display device 1004. Compared with the configuration of the LED display device 1003 of the third embodiment, the LED display device 1004 includes a correction amount calculation unit 32 instead of the correction amount calculation unit 18, and further includes a communication unit 33 and a communication terminal 34.

The communication unit 33 transmits / receives information to / from the video control device 5 via the communication terminal 34. The brightness reduction detection unit 29 acquires the cumulative lighting time of the LED element 102 of the first LED display unit 22 from the lighting time storage unit 28, and sets the lighting time of the LED element 102 of the second LED display unit 24 from the brightness reduction rate storage unit 26. The relationship of the brightness reduction rate is acquired, and the brightness reduction rate of the LED element 102 of the first LED display unit 22 is calculated based on these. Then, the brightness reduction detection unit 29 transmits the calculated brightness reduction rate of the LED element 102 of the first LED display unit 22 to the image control device 5 via the communication unit 33 and the communication terminal 34.

The correction amount calculation unit 32 acquires the brightness reduction rate of the LED element 102 of the first LED display unit 22 from the brightness reduction detection unit 29, and acquires the processing result of the video control device 5 from the communication unit 33. Then, the correction amount calculation unit 32 calculates the offset amount of the video signal based on these.

<D-2. Operation>
FIG. 18 is a flowchart showing the offset processing of the LED display system 400. Hereinafter, the offset processing of the LED display system 400 will be described with reference to FIG. First, the luminance reduction detection unit 58 of the video control device 5 determines whether or not the set time has elapsed since the previous offset processing (step S401). Here, the set time is a unit time of offset processing, and is, for example, 100 hours. The brightness reduction detection unit 58 repeats step S401 until the set time elapses from the previous offset process. When the set time has elapsed since the previous offset processing (Yes in step S401), the luminance reduction detection unit 58 displays the cumulative lighting time of each LED element 102 of the first LED display unit 22 and the second LED display from each LED display device 1004. Information representing the relationship between the lighting time of each LED element 102 of the unit 24 and the brightness reduction rate is acquired via the communication unit 56 and stored in the storage unit 57 (step S402).

Next, the brightness reduction detection unit 58 determines the cumulative lighting time of each LED element 102 of the first LED display unit 22 and the lighting time and brightness reduction of each LED element 102 of the second LED display unit 24 stored in the storage unit 57. Similar to the brightness reduction detection unit 29 of the third embodiment, the minimum brightness reduction rate kr (t) _min , kg (t) _min , kb (t) _min of the LED element 102 is extracted from the information representing the relationship with the rate. Further, the threshold values YRth, YGth, and YBth of the brightness reduction rate are calculated (step S404).

Next, the brightness reduction detection unit 58 determines whether or not there is an LED element 102 whose brightness reduction rate exceeds the threshold values YRth, YGth, and YBth (step S405). When there is no LED element 102 whose luminance reduction rate exceeds the threshold values YRth, YGth, and YBth, the image control device 5 shifts to the process of step S407 without performing the offset process. When the LED element 102 whose luminance reduction rate exceeds the threshold values YRth, YGth, and YBth exists, the generation unit 52 performs offset processing on the video signal (step S406). The output unit 53 transmits the video generated by the generation unit 52 to each LED display device 1004 via an output terminal 54 such as DVI. In this way, the image is displayed on each LED display device 1004.

After step S406 or in step S405, when there is no LED element 102 whose luminance reduction rate exceeds the threshold values YRth, YGth, YBth, the video control device 5 determines whether or not the video display is completed (step S407). .. If Yes in step S407, the series of offset processing ends. When the video display is continued (No in step S407), the process of the video control device 5 returns to step S401.

When the video control device 5 is a general-purpose information processing device such as a personal computer (PC), the video is not enlarged in the offset processing, and the content of the video to be displayed is offset processed or the video to be displayed is arranged. You may make changes and the like.

Further, the generation unit 52 of the video control device 5 may perform only the minimum offset processing such as enlargement / reduction processing. In this case, the luminance reduction detection unit 58 transmits the remaining offset processing, for example, an instruction to move the display position of the image in the vertical or horizontal direction to each LED display device 1004 via the communication unit 56. Then, in each LED display device 1004, the correction amount calculation unit 32 calculates the offset correction amount for each LED display device 1004, and the offset processing unit 19 performs the offset processing.

Further, when the display screen of the LED display system 400 is high-definition and large, the deviation of the image due to the offset processing becomes relatively inconspicuous with respect to the size of the display screen. Therefore, in each LED display device 1004, the luminance correction unit 31 may be omitted and only the offset processing may be performed.

In the above, an example in which the offset processing based on the calculation of the luminance reduction rate of each LED element 102 described in the third embodiment is applied to the LED display system 400 has been described. However, it is also possible to apply the offset processing described in the first and second embodiments to the LED display system 400.

<D-3. Effect>
The LED display system 400 of the fourth embodiment includes a plurality of LED display devices 1004 and a video control device 5 that communicates with each LED display device 1004. Each LED display device 1004 includes a first LED display unit 22 having a plurality of first LED elements arranged in a plurality of directions, a first LED drive unit 21 that drives each first LED element according to a video signal, and a first LED element. A brightness reduction rate storage unit 26 that stores brightness reduction rate information indicating the relationship between the lighting time and the brightness reduction rate of the second LED element having the same brightness reduction characteristic, and an integration unit that calculates the cumulative lighting time of each first LED element. 27 and a communication unit 33, which is a first communication unit that communicates with the video control device 5. The image control device 5 has a communication unit 56 which is a second communication unit that communicates with each LED display device 1004, a cumulative lighting time of each first LED element acquired from each LED display device 1004, and a decrease in brightness of the second LED element. The brightness reduction rate of each first LED element is calculated based on the rate information, and the brightness reduction rate is larger than the third threshold value determined based on the minimum minimum brightness reduction rate of the brightness reduction rates of each second LED element. It includes a luminance reduction detection unit 58 that detects one LED element as a target LED element, and a generation unit 52 that is an offset processing unit that offsets a video signal when the number of target LED elements is equal to or greater than the fourth threshold value.

In the LED display system 400 of the fourth embodiment, the luminance reduction rate kr (t), kg (t), kb (t) is larger than the threshold values YRth, YGth, YBth in the LED element 102 of each LED display device 1004. When a certain number or more of the LED elements 102 are present, the video signal is offset. As a result, the brightness reduction rate is leveled among the LED elements 102. Therefore, by correcting the brightness according to the LED element 102 whose brightness is extremely lowered, the entire screen of the LED display device 1004 does not become excessively dark. As a result, it becomes easy to maintain the uniformity of the brightness and the white balance, and it is possible to suppress the variation in the brightness of the image display screen.

In the LED display device 1001-1003 of the first embodiment, the video signal is enlarged to, for example, 105%, and a part necessary for display is selected from the enlarged image, so that the image is displayed on the LED display unit 14 at the time of offset. The area where is not displayed did not appear. On the other hand, in the LED display system 400 of the fourth embodiment, if the image control device 5 performs a process of moving the display position of the image in the LED display device 1004 or a process of changing the arrangement of the image, the LED display device The offset processing unit 19 of 1004 does not need to perform image enlargement processing. Therefore, the image quality does not deteriorate due to the image enlargement processing.

Further, in the LED display system 400, by using the video control device 5, it is possible to adopt a processing circuit or processing device related to video signal processing in the LED display device 1004, which is cheaper and has lower processing performance. Therefore, the cost of the LED display system 400 can be reduced.

Further, the larger the display screen of the LED display system 400 is, the more effectively the variation in brightness due to the offset processing can be suppressed. Further, the deviation of the image due to the offset processing becomes relatively inconspicuous as the display screen becomes larger, and the discomfort given to the user is extremely reduced. Therefore, in the LED display system 400 having a high-definition and large screen, the same effect can be obtained only by the offset processing by omitting the luminance correction unit 31 of the LED display device 1004.

<D-4. Modification example>
The video control device 5 notifies from the LED display device 1004 when there is an LED element 102 having a luminance reduction rate kr (t), kg (t), and kb (t) larger than the threshold values YRth, YGth, and YBth. It may receive and control the image. Since the video control device 5 can use a general-purpose information processing device such as a PC, the flexibility of the function is high. Therefore, the user may set the number of notifications received by the video control device 5 until the video is controlled, or the method of shifting the video (amount, direction, frequency, enlargement / reduction, rotation, etc.) in the offset processing.

<E. Hardware configuration>
Various configurations (hereinafter, referred to as "offset processing unit 19 and the like") in the LED display device 1001-1004 and the video control device 5 described above include the LED display unit 14, the first LED display unit 22, and the second LED display unit 24. Except, it is realized by the processing circuit 81 shown in FIG. Dedicated hardware may be applied to the processing circuit 81, or a processor that executes a program stored in the memory may be applied. The processor is, for example, a central processing unit, a processing unit, an arithmetic unit, a microprocessor, a microcomputer, a DSP (Digital Signal Processor), or the like.

When the processing circuit 81 is dedicated hardware, the processing circuit 81 may be, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), or an FPGA (Field-Programmable). GateArray), or a combination of these. Each of the functions of each part such as the offset processing unit 19 may be realized by a plurality of processing circuits 81, or the functions of each part may be collectively realized by one processing circuit.

When the processing circuit 81 is a processor, the functions of the offset processing unit 19 and the like are realized by a combination with software or the like (software, firmware or software and firmware). Software and the like are described as programs and stored in memory. As shown in FIG. 20, the processor 82 applied to the processing circuit 81 realizes the functions of each part by reading and executing the program stored in the memory 83. In other words, it can be said that this program causes the computer to execute the procedure or method of the offset processing unit 19 and the like. Here, the memory 83 is a non-volatile or non-volatile memory such as a RAM (RandomAccessMemory), a ROM (ReadOnlyMemory), a flash memory, an EPROM (ErasableProgrammableReadOnlyMemory), and an EEPROM (ElectricallyErasableProgrammableReadOnlyMemory). Volatile semiconductor memory, HDD (Hard Disk Drive), magnetic disk, flexible disk, optical disk, compact disk, mini disk, DVD (Digital Versatile Disk) and its drive device, etc., or any storage medium used in the future. You may.

The configuration in which each function of the offset processing unit 19 and the like is realized by either hardware or software has been described above. However, the present invention is not limited to this, and a configuration may be configured in which a part of the offset processing unit 19 or the like is realized by dedicated hardware and another part is realized by software or the like. For example, the offset processing unit 19 realizes its function by a processing circuit as dedicated hardware, and other than that, the processing circuit 81 as a processor 82 reads and executes a program stored in the memory 83 to execute the function. It is possible to realize.

As described above, the processing circuit can realize each of the above-mentioned functions by hardware, software, or a combination thereof. The lighting time storage units 16 and 28, the luminance reduction rate storage unit 26, and the storage unit 57 are composed of a memory 83, but they may be composed of a single memory 83, or each of them may be an individual memory. It may be composed of.

It is possible to freely combine each embodiment, and to appropriately modify or omit each embodiment. The above description is exemplary in all embodiments. It is understood that innumerable variations not illustrated can be assumed.

5 Video control device, 11,51 input terminal, 12 signal processing unit, 13 LED drive unit, 14 LED display unit, 15 integration unit, 16,28 lighting time storage unit, 17,29,58 brightness reduction detection unit, 18 correction Quantity calculation unit, 19 offset processing unit, 21 1st LED drive unit, 22 1st LED display unit, 23 2nd LED drive unit, 24 2nd LE display unit, 25 brightness measurement unit, 26 brightness reduction rate storage unit, 27 integration unit, 30 Correction coefficient calculation unit, 31 brightness correction unit, 32 correction amount calculation unit, 33,56 communication unit, 34,55 communication terminal, 52 generation unit, 53 output unit, 54 output terminal, 57 storage unit, 60 cable, 60a video cable , 60b communication cable, 81 processing circuit, 82 processor, 83 memory, 101 LED, 102 LED element, 400 LED display system, 1001-1004 LED display device.

Claims (7)

1. An LED display unit having a plurality of LED elements arranged in a plurality of directions,
   An LED drive unit that drives each LED element according to a video signal,
   An integrating unit that calculates the cumulative lighting time of each LED element,
   A brightness reduction detection unit that detects the LED element having a longer cumulative lighting time than the first threshold value determined based on the shortest cumulative lighting time of the cumulative lighting time of each LED element as a target LED element.
   An offset processing unit that offsets the video signal when the number of target LED elements is equal to or greater than the second threshold value is provided.
   LED display device.
2. The sum of the cumulative lighting time differences of the plurality of adjacent LED elements is calculated for each direction of the plurality of directions in which the plurality of LED elements are arranged, and the direction in which the sum of the cumulative lighting time differences is maximum is set as the offset direction. With an additional offset direction determination unit,
   The offset processing unit offsets the video signal in the offset direction.
   The LED display device according to claim 1.
3. A first LED display unit having a plurality of first LED elements arranged in a plurality of directions,
   A first LED drive unit that drives each of the first LED elements according to a video signal,
   A brightness reduction rate storage unit for storing brightness reduction rate information indicating the relationship between the lighting time and the brightness reduction rate of the second LED element having the same brightness reduction characteristics as the first LED element.
   An integrating unit that calculates the cumulative lighting time of each of the first LED elements,
   Based on the cumulative lighting time of each of the first LED elements and the brightness reduction rate information of the second LED element, the brightness reduction rate of each of the first LED elements is calculated, and the brightness reduction rate of each of the second LED elements is calculated. A brightness reduction detection unit that detects the first LED element whose brightness reduction rate is larger than the third threshold value determined based on the minimum minimum brightness reduction rate as a target LED element.
   An offset processing unit that offsets the video signal when the number of target LED elements is equal to or greater than the fourth threshold value is provided.
   LED display device.
4. A second LED display unit having the second LED element,
   A second LED drive unit that drives the second LED element,
   A luminance measuring unit for measuring the luminance of the second LED element is further provided.
   The integrating unit calculates the cumulative lighting time of the second LED element, and calculates the cumulative lighting time.
   The brightness reduction rate information is obtained based on the brightness of the second LED element measured by the brightness measuring unit and the cumulative lighting time of the second LED element calculated by the integrating unit.
   The LED display device according to claim 3.
5. For each direction in the plurality of directions in which the plurality of LED elements are arranged, the sum of the brightness reduction rate differences of the plurality of adjacent LED elements is calculated, and the direction in which the sum of the brightness reduction rate differences is maximum is the offset direction. Further equipped with an offset direction determination unit
   The offset processing unit offsets the video signal in the offset direction.
   The LED display device according to claim 3 or 4.
6. With multiple LED display devices
   An LED display system including a video control device that communicates with each of the LED display devices.
   Each LED display device is
   A first LED display unit having a plurality of first LED elements arranged in a plurality of directions,
   A first LED drive unit that drives each of the first LED elements according to a video signal,
   A brightness reduction rate storage unit for storing brightness reduction rate information indicating the relationship between the lighting time and the brightness reduction rate of the second LED element having the same brightness reduction characteristics as the first LED element.
   An integrating unit that calculates the cumulative lighting time of each of the first LED elements,
   A first communication unit that communicates with the video control device is provided.
   The video control device is
   A second communication unit that communicates with each of the LED display devices,
   Based on the cumulative lighting time of each of the first LED elements acquired from each of the LED display devices and the brightness reduction rate information of the second LED element, the brightness reduction rate of each of the first LED elements is calculated, and the brightness reduction rate of each of the first LED elements is calculated. A brightness reduction detection unit that detects the first LED element having a brightness reduction rate larger than a third threshold value determined based on the minimum brightness reduction rate of the two LED elements as a target LED element, and a brightness reduction detection unit.
   An offset processing unit that offsets the video signal when the number of target LED elements is equal to or greater than the fourth threshold value is provided.
   LED display system.
7. It is a display method of an LED display device provided with an LED display unit having a plurality of LED elements arranged in a plurality of directions.
   Each LED element is driven according to the video signal,
   Calculate the cumulative lighting time of each LED element and calculate
   The LED element having a longer cumulative lighting time than the first threshold value determined based on the shortest cumulative lighting time among the cumulative lighting times of each LED element is detected.
   When the number of the LED elements whose cumulative lighting time is longer than the first threshold value is equal to or larger than the second threshold value, the video signal is offset.
   Display method of LED display device.

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