WO2020230281A1

WO2020230281A1 - Led display

Info

Publication number: WO2020230281A1
Application number: PCT/JP2019/019208
Authority: WO
Inventors: 遼堀川; 孝博大岡; 洋和田口
Original assignee: 三菱電機株式会社
Priority date: 2019-05-15
Filing date: 2019-05-15
Publication date: 2020-11-19

Abstract

An LED display is provided which, even when pixel defects have occurred, can display video that appears to have uniform brightness without the pixel defects being conspicuous. This LED display is provided with an LED display unit, a failure detection unit, a brightness correction unit, a correction coefficient calculation unit, and a drive unit. The LED display unit is provided with a plurality of LEDs arranged in a matrix. The failure detection unit detects failures of the LEDs. The brightness correction unit corrects a video signal such that the brightness of 2 or more LEDs included in the plurality of LEDs becomes uniform. Further, the brightness correction unit corrects the video signal in accordance with the brightness correction coefficient. The brightness correction unit outputs the corrected video signal. The correction coefficient calculation unit calculates a brightness correction coefficient such that, if failure of a first LED has been detected by the failure detection unit, then the brightness of a second LED different from the first LED changes. The drive unit drives the plurality of LEDs in accordance with the corrected video signal.

Description

LED display device

The present invention relates to an LED display device.

LED display devices equipped with light emitting diodes (LEDs: Light Emitting Diodes) are widely used for displaying advertisements outdoors and indoors.

Conventionally, the LED display device has a pixel pitch of 3 mm or more and has been used as a large-scale outdoor display device. However, in recent years, with the miniaturization of LEDs, the cost reduction of LEDs, and the narrowing of the pixel pitch of LED display devices, the viewing distance of LED display devices has become shorter, and LED display devices are used for indoor monitoring applications. The number of cases is increasing.

For example, an LED display device having a narrow pixel pitch of 1.5 mm, 1.9 mm, etc. has been put on the market as an indoor display device. The LED display device is used for displaying a personal computer image in a conference room, displaying a personal computer image for monitoring purposes, and the like. When the LED display device is used to display a personal computer image for surveillance purposes, the LED display device often displays a personal computer image close to a still image.

In an LED display device, in many cases, a large number of LEDs are arranged in a matrix on a substrate to form a display module. In addition, a display unit is configured by combining a plurality of display modules. Further, a plurality of display units are arbitrarily combined to form a video display surface having a desired size.

In order to display a high-quality image having uniform brightness on an LED display device including a large number of LEDs, it is desired that the brightness of many LEDs is uniform. However, in many cases, the characteristics of many LEDs are not uniform. Therefore, when the same drive signal is supplied to a large number of LEDs, the brightness of the large number of LEDs is not uniform. Therefore, by adjusting the drive signals supplied to a large number of LEDs, the brightness of the large number of LEDs is made uniform. In this case, a large number of LEDs provided in the display unit or display module are turned on. Further, an image of the display unit or the display module is captured with a large number of LEDs turned on. In addition, the brightness of many LEDs is measured by the captured image. Further, the drive signal supplied to the residual LED is adjusted so that the brightness of the residual LED approaches the brightness of the LED having the lowest brightness.

Also, the brightness of the LED decreases as the cumulative lighting time of the LED increases. Therefore, the cumulative lighting time of a large number of LEDs becomes non-uniform depending on the content of the image displayed on the LED display device. Therefore, depending on the content of the image displayed on the LED display device, the reduction rate of the brightness of many LEDs becomes non-uniform. As a result, as the usage time of the LED display device increases, the brightness and chromaticity of many LEDs provided in the LED display device become non-uniform. Therefore, a technique for solving this problem has been proposed.

For example, in the technique described in Patent Document 1, a plurality of display LEDs are mounted on the front surface of a circuit board (paragraph 0015). In addition, the reference LED is mounted on the back surface of the circuit board. The circuit board drives a plurality of display LEDs and reference LEDs (paragraph 0015). Since a plurality of display LEDs can deteriorate over time, there is a need for a mechanism for performing color adjustment (paragraph 0015). Therefore, the output from the reference LED is detected (paragraph 0016). The output from the reference LED is required for the automatic color adjustment process (paragraph 0016).

Japanese Unexamined Patent Publication No. 2014-102484

If one LED included in a large number of LEDs provided in an LED display device fails and does not light up, a pixel defect occurs. Pixel defects can be eliminated by performing repairs by replacing the failed LED with a non-failed LED. However, when the LED display device has a narrow pixel pitch of about 1 mm, delicate and advanced technology is required to perform the repair. Repairs that require such delicate and sophisticated techniques are difficult to perform after the LED display device has been put into operation. For this reason, at present, even if only one LED contained in tens of thousands of LEDs fails, it has become mainstream to replace a module having tens of thousands of LEDs with a new module for repair. There is. Then, in order to carry out such repair, the power of the LED display device must be turned off or the screen of the LED display device must be hidden.

However, when the LED device is incorporated in the display system that is required to operate 24 hours a day, the power of the LED display device is turned off or the screen of the LED display device is hidden in order to eliminate the pixel defect. This means that the display must be stopped in order to eliminate the pixel defect. It leads to a great risk in the operation of the display system. This problem is especially noticeable when the display system is used for surveillance purposes.

The present invention has been made in view of these problems. An object to be solved by the present invention is to provide an LED display device capable of displaying an image in which pixel defects are inconspicuous and appear to have uniform brightness even when pixel defects occur.

The LED display device includes an LED display unit, a failure detection unit, a brightness correction unit, a correction coefficient calculation unit, and a drive unit.

The LED display unit includes a plurality of LEDs. The plurality of LEDs are arranged in a matrix.

The failure detection unit detects the failure of each LED included in the plurality of LEDs.

The brightness correction unit corrects the video signal so that the brightness of two or more LEDs included in the plurality of LEDs becomes uniform. Further, the luminance correction unit corrects the video signal according to the luminance correction coefficient. The luminance correction unit outputs the corrected video signal.

In the correction coefficient calculation unit, when a failure of the first LED included in the plurality of LEDs is detected by the failure detection unit, the brightness of the second LED included in the plurality of LEDs, which is different from the first LED, changes. The brightness correction coefficient is calculated so as to be performed.

The drive unit drives a plurality of LEDs according to the corrected video signal.

According to the present invention, the video signal is corrected to make the brightness of the LED uniform. Further, when the first LED fails, the video signal is corrected to change the brightness of the second LED. Therefore, even if the first LED fails, it is possible to provide an LED display device capable of displaying an image having uniform brightness without conspicuous pixel defects caused by the failure of the first LED.

The purpose, features, aspects and advantages of the present invention will be made clearer by the following detailed description and accompanying drawings.

It is a block diagram which illustrates the light emitting diode (LED: Light Emitting Diode) display device of Embodiments 1 and 2. It is a top view which shows typically the LED display part provided in the LED display device of Embodiments 1 and 2. It is a top view which schematically illustrates one pixel provided in the LED display device of Embodiments 1 and 2. It is a timing chart for explaining the PWM drive performed in the LED display device of Embodiments 1 and 2. FIG. 5 is a plan view schematically illustrating an LED display unit including pixel defects provided in the LED display device of the first embodiment. It is a flowchart which shows the operation of the LED display device of Embodiments 1 and 2. It is a figure which shows the example of the distribution of the luminance value in the LED display part provided in the LED display device of Embodiment 1 when the correction which makes a pixel defect inconspicuous is not performed. It is a figure which shows the example of the distribution of the luminance value in the LED display part provided in the LED display device of Embodiment 1 when the correction which makes a pixel defect inconspicuous is performed. It is a figure which shows the example of the distribution of the luminance value in the LED display part provided in the LED display device of Embodiment 2 when the correction which makes a pixel defect inconspicuous is performed. It is a figure which shows the example of the distribution of the luminance correction factor θ in the LED display part provided in the LED display device of Embodiment 2 when the correction which makes a pixel defect inconspicuous is performed.

1 Embodiment 1
1.1 LED Display Device FIG. 1 is a block diagram illustrating a light emitting diode (LED) display device according to the first embodiment.

As shown in FIG. 1, the LED display device 1 of the first embodiment has a video signal input terminal 101, a video signal processing unit 102, a brightness correction unit 103, a drive unit 104, an LED display unit 105, and a failure detection unit 106. , Correction coefficient calculation unit 107, external control communication terminal 108, external communication unit 109, microcomputer (microcomputer) 110, and memory 111. The drive unit 104 and the failure detection unit 106 constitute the LED driver 120.

FIG. 2 is a plan view schematically showing an LED display unit provided in the LED display device of the first embodiment.

As shown in FIG. 2, the LED display unit 105 includes a plurality of LEDs 130 arranged in a matrix.

A video signal is input to the video signal input terminal 101 shown in FIG. 1 from an external device such as a personal computer (PC).

The video signal processing unit 102 processes the input video signal and outputs the processed video signal. The processing performed by the video signal processing unit 102 includes video signal processing, selection processing, and the like. Video signal processing includes gamma correction and the like. The selection process includes a process of selecting a portion necessary for displaying an image by the LED display device 1 from the input video signal. When the processing performed by the video signal processing unit 102 includes selection processing, the LED display unit 105 displays a part of the video represented by the input video signal. When the processing performed by the video signal processing unit 102 does not include the selection processing, the LED display unit 105 displays the entire video represented by the input video signal.

The brightness correction unit 103 corrects the processed video signal according to the brightness correction coefficient, and outputs the corrected video signal. As a result, the brightness of the plurality of LEDs 130 is corrected according to the brightness correction coefficient, and the brightness of the image displayed on the LED display unit 105 is corrected according to the brightness correction coefficient. The luminance correction unit 103 corrects the video signal according to the luminance correction coefficient by changing the signal level of the video signal according to the luminance correction coefficient.

The drive unit 104 drives a plurality of LEDs 130 according to the corrected video signal. As a result, the light emission of the plurality of LEDs 130 is controlled according to the corrected video signal, and the brightness of the plurality of LEDs 130 is controlled according to the corrected video signal. As a result, the LED display unit 105 displays an image corresponding to the corrected image signal. Desirably, the drive unit 104 drives each LED 140 included in the plurality of LEDs 130 by pulse width modulation (PWM).

Each LED 140 included in the plurality of LEDs 130 constitutes one pixel.

FIG. 3 is a plan view schematically illustrating one pixel provided in the LED display device of the first embodiment. The LED display unit 105 displays a full-color image. Therefore, as shown in FIG. 3, each LED 140 constituting one pixel includes a red (R) LED 151, a green (G) LED 152, and a blue (B) LED 153. Each of the R LED 151, the G LED 152, and the B LED 153 constitutes a sub-pixel. The LED display unit 105 may display a monochromatic image. In this case, each LED 140 may be composed of LEDs of one color. The LED display unit 105 may be replaced with an LED display unit having a different structure.

The failure detection unit 106 illustrated in FIG. 1 detects a failure of each LED 140 included in the plurality of LEDs 130. The failure detection unit 106 detects a failure in the short-circuit mode and the open mode of each LED 140 by monitoring the voltage and / or current supplied to each LED 140 while the drive unit 104 is driving each LED 140, for example. To do.

When the failure detection unit 106 detects a failure of each LED 140, the correction coefficient calculation unit 107 calculates the brightness correction coefficient at the time of failure that constitutes the above-mentioned brightness correction coefficient. The brightness correction coefficient at the time of failure is a brightness correction coefficient for correction that makes the pixel defects caused by the failure of each LED 140 inconspicuous.

A control signal is input to the external control communication terminal 108 from an external device such as a PC. The input control signal includes a control signal for controlling the LED display device 1.

The external communication unit 109 receives the input control signal.

The microcomputer 110 receives the input control signal via the external control communication terminal 108 and the external communication unit 109. Further, the microcomputer 110 controls the brightness of the plurality of LEDs 130 by controlling the correction coefficient calculation unit 107. Further, the microcomputer 110 stores the luminance correction coefficient calculated by the correction coefficient calculation unit 107 in the memory 111.

1.2 Control of LED lighting The lighting of each LED 140 included in the plurality of LEDs 130 is preferably controlled by a PWM method. In this case, the drive unit 104 supplies each LED 140 with a drive signal having a duty ratio proportional to the signal level of each LED 140. Each LED 140 lights up during the on period of the supplied drive signal. As a result, each LED 140 has a brightness proportional to the signal level of each LED 140.

FIG. 4 is a timing chart illustrating PWM drive performed in the LED display device of the first embodiment. FIG. 4A is a diagram illustrating a waveform of a signal including a pulse repeatedly generated in a basic period of PWM drive. FIG. 4B is a diagram illustrating a waveform of a drive signal having a duty ratio of 85%. FIG. 4C is a diagram illustrating a waveform of a drive signal having a duty ratio of 80%.

The basic period shown in FIG. 4A is one frame period or less of the video signal. The drive signal shown in FIG. 4B includes pulses that are repeatedly emitted in the basic period and have a pulse width of 85% of the basic period. The drive signal shown in FIG. 4 (c) includes a pulse that is repeatedly emitted in the basic cycle and has a pulse width of 80% of the basic cycle. The brightness of each LED 140 when the drive signal shown in FIG. 4 (b) is supplied to each LED 140 included in the plurality of LEDs 130, and the case where the drive signal shown in FIG. 4 (c) is supplied to each LED 140. The brightness of each LED 140 is different from each other. Therefore, the luminance correction unit 103 changes the signal level of the video signal according to the luminance correction coefficient, and the drive unit 104 changes the duty ratio of the drive signal supplied to each LED 140 according to the signal level of each LED 140. The brightness of the LED 140 can be changed according to the brightness correction coefficient.

1.3 Necessity of correction to make the brightness of LEDs uniform The plurality of LEDs 130 have different characteristics from each other. Therefore, the plurality of LEDs 130 have different brightness from each other. Therefore, if the video signal is not corrected so that the brightness of the plurality of LEDs 130 becomes uniform, the video displayed on the LED display unit 105 becomes grainy and uneven brightness or the like occurs. Therefore, the luminance correction unit 103 preferably corrects the video signal so that the luminance of the plurality of LEDs 130 becomes uniform.

1.4 Change in correction due to detection of LED failure FIG. 5 is a plan view schematically showing an LED display unit including pixel defects provided in the LED display device of the first embodiment.

As shown in FIG. 5, when the first LED 171 included in the plurality of LED 130s fails, the plurality of LEDs 130 are corrected to make the first LED 171 causing the pixel defect 160 and the pixel defect 160 inconspicuous. Includes a second LED 172 of interest. The second LED 172 is an LED different from the first LED 171 and is, for example, an LED adjacent to the first LED 171.

When the second LED 172 is an LED adjacent to the first LED 171, the second LED 172 is an LED arranged above the first LED 171 and an LED arranged below the first LED 171. LED arranged to the left of LED171, LED arranged to the right of the first LED171, LED arranged on the upper left of the first LED171, LED arranged on the upper right of the first LED171, first LED171. The LED is arranged at the lower left of the above, and the LED is arranged at the lower right of the first LED 171.

When the failure of each LED 140 included in the plurality of LEDs 130 is not detected by the failure detection unit 106, the brightness correction unit 103 corrects the video signal so that the brightness of the plurality of LEDs 130 becomes uniform. At that time, the luminance correction unit 103 corrects the video signal according to the luminance correction coefficient C for making the brightness of the LED uniform.

On the other hand, when the failure detection unit 106 detects a failure of the first LED 171 included in the plurality of LEDs 130, the brightness correction unit 103 other than the first LED 171 and the second LED 172 included in the plurality of LEDs 130. The video signal is corrected so that the brightness of the two or more LEDs 174 becomes uniform. At that time, the brightness correction unit 103 corrects the first signal including the brightness of the two or more LEDs 174 included in the video signal according to the brightness correction coefficient C for correction to make the brightness of the LEDs uniform. .. Further, when the failure of the first LED 171 is detected by the failure detection unit 106, the brightness correction unit 103 corrects the video signal so that the brightness of the second LED 172 changes. For example, when the failure detection unit 106 detects a failure of the first LED 171, the brightness correction unit 103 corrects the video signal so that the brightness of the second LED 172 becomes high. At that time, the luminance correction unit 103 makes the second signal, which indicates the luminance of the second LED 172, included in the video signal, according to the luminance correction coefficient C_t at the time of failure for correction for making the pixel defect 160 inconspicuous. to correct.

Correcting the video signal so that the brightness of the second LED 172 becomes high means that the brightness of the second LED 172 after the correction for making the pixel defect 160 inconspicuous is corrected to make the pixel defect 160 inconspicuous. It means that the video signal is corrected so as to be higher than the brightness of the second LED 172 before being performed, and the brightness of the second LED 172 after the correction for making the pixel defect 160 inconspicuous is the brightness of the LED. It means that the video signal is corrected so as to be higher than the target brightness of the second LED 172 when the correction is performed to make the image uniform.

1.5 Luminance correction coefficient C for correction to make the LED brightness uniform
When the brightness correction coefficient C for the correction to make the brightness of the LEDs uniform is calculated, a plurality of LEDs 130 are turned on. In addition, images of the plurality of LEDs 130 are captured with the plurality of LEDs 130 turned on. In addition, the brightness of each LED 140 included in the plurality of LEDs 130 is measured from the captured image. Further, the brightness correction coefficient C for adjusting the drive signal supplied to the remaining LED so that the brightness of the remaining LED approaches the brightness of the LED having the lowest brightness is calculated.

The brightness correction coefficient C is the brightness correction coefficient Cr (uh, uv) of the R of the LED arranged at the horizontal pixel position uh and the vertical pixel position uv, the brightness correction coefficient Cg (uu, uv) of G, and the brightness correction coefficient of B. Includes Cb (uh, uv). The brightness correction coefficient Cr (uh, uv) of R, the brightness correction coefficient Cg (uh, uv) of G, and the brightness correction coefficient Cb (uh, uv) of B are the brightness values Yr (uh, uv) of R of the LED. , G brightness value Yg (uh, uv) and B brightness value Yb (uh, uv), and R target brightness value Yr_t, G target brightness value Yg_t, and B target brightness value Yb_t. It is represented by 1), equation (2) and equation (3). The horizontal pixel position uh is an integer of 0 or more and 5 or less. The vertical pixel position uv is each of integers of 0 or more and 5 or less.

Cr (uh, uv) = Yr_t / Yr (uh, uv) ... (1)
Cg (uh, uv) = Yg_t / Yg (uh, uv) ... (2)
Cb (uh, uv) = Yb_t / Yb (uh, uv) ... (3)

The target luminance values Yr_t, Yg_t and Yb_t are the LEDs arranged at the horizontal pixel position uh and the vertical pixel position uv according to the luminance correction coefficients Cr (uh, uv), Cg (uh, uv) and Cb (uh, uv). It is the brightness value of R, G and B of the LED when the signal indicating the brightness is corrected.

The luminance correction coefficients Cr (uh, uv), Cg (uh, uv) and Cb (uh, uv), and the target luminance values Yr_t, Yg_t and Yb_t are stored in the memory 111.

The stored luminance correction coefficients Cr (uh, uv), Cg (uh, uv) and Cb (uv, uv), and the target luminance values Yr_t, Yg_t and Yb_t are obtained after a plurality of LED display units 105 are arranged. It is used for the brightness correction calculation between the plurality of LED display units 105 at the time of initial installation.

The stored target luminance values Yr_t, Yg_t and Yb_t are set to be smaller than the luminance values of R, G and B of the LED having the lowest luminance, respectively. As a result, the video signal can be corrected so that the brightness of the plurality of LEDs 130 becomes uniform.

1.6 Luminance correction coefficient C_t at the time of failure for correction to make pixel defects inconspicuous
The brightness correction coefficient C_t at the time of failure for correction to make the pixel defect 160 inconspicuous is determined by the correction coefficient calculation unit 107 when the failure of the first LED 171 included in the plurality of LEDs 130 is detected by the failure detection unit 106. It is calculated. The brightness correction coefficient C_t at the time of failure is calculated so that the brightness of the second LED 172 changes, for example, the brightness of the second LED 172 is calculated to be high. For example, when the failure of the first LED 171 is detected by the failure detection unit 106, the correction coefficient calculation unit 107 calculates the brightness correction factor θ at the time of failure, and calculates the calculated brightness correction factor θ at the time of failure of the LED. By multiplying the brightness correction coefficient C for the correction to make the brightness uniform, the brightness correction coefficient C_t at the time of failure is calculated.

The brightness correction coefficient C_t at the time of failure is the brightness correction coefficient Cr_t (uh, uv) at the time of failure of the LED R arranged at the horizontal pixel position uh and the vertical pixel position uv, and the brightness correction coefficient Cg_t (uu) at the time of failure of G. , Uv) and the brightness correction coefficient Cb_t (uh, uv) at the time of failure of B are included. The luminance correction coefficient Cr_t (uh, uv) at the time of failure of R, the luminance correction coefficient Cg_t (uh, uv) at the time of failure of G, and the luminance correction coefficient Cb_t (uh, uv) at the time of failure of B are the above-mentioned R. Luminance correction coefficient Cr (uh, uv), G brightness correction coefficient Cg (uh, uv), B brightness correction coefficient Cb (uu, uv), and brightness correction factor θr at the time of failure of R, at the time of failure of G It is expressed by the equations (4), (5) and (6) using the luminance correction factor θg and the luminance correction factor θb at the time of failure of B. The horizontal pixel position uh is an integer of 0 or more and 5 or less. The vertical pixel position uv is each of integers of 0 or more and 5 or less.

Cr_t (uh, uv) = Cr (uh, uv) × θr ... (4)
Cg_t (uh, uv) = Cg (uh, uv) × θg ... (5)
Cb_t (uh, uv) = Cb (uh, uv) × θb ... (6)

The brightness correction factors θr, θg and θb at the time of failure can take values within the range represented by the equations (7), (8) and (9).

1 ≦ θr <Cr (uh, uv) ・・・ (7)
1 ≦ θg <Cg (uh, uv) ・・・ (8)
1 ≦ θb <Cb (uh, uv) ・・・ (9)

As described above, the target luminance values Yr_t, Yg_t and Yb_t are set smaller than the luminance values of R, G and B of the LED having the lowest luminance, respectively. Therefore, the luminance correction coefficients Cr_t (uh, uv), Cg_t (uh, uv) and Cb_t (uh, uv) at the time of failure are represented by the equations (10), (11) and (12). Can be set to be larger than 1.

Cr_t (uh, uv)> 1 ... (10)
Cg_t (uh, uv)> 1 ... (11)
Cb_t (uh, uv)> 1 ... (12)

1.7 Operation of LED Display Device FIG. 6 is a flowchart showing the operation of the LED display device according to the first embodiment.

In step S101 shown in FIG. 6, it is determined whether or not a failure of an arbitrary first LED 171 included in the plurality of LEDs 130 has been detected by the failure detection unit 106. If it is determined that the failure of the first LED 171 is detected, the following steps S102, S103 and S104 are sequentially executed. If it is determined that the failure of the first LED 171 has not been detected, step S101 is executed again without executing subsequent steps S102, S103 and S104.

In step S102, the correction coefficient calculation unit 107 detects the coordinates of the failed first LED 171.

In step S103, the correction coefficient calculation unit 107 calculates the brightness correction factor θ at the time of failure used to correct the brightness of the second LED 172 adjacent to the failed first LED 171.

In step S104, the luminance correction unit 103 corrects the video signal using the calculated luminance correction factor θ at the time of failure. At that time, the brightness correction unit 103 multiplies the calculated brightness correction factor θ at the time of failure by the brightness correction coefficient C so that the brightness correction coefficient C_t at the time of failure is multiplied by the brightness of the second LED 172. The second signal including the brightness of the second LED 172 included in the video signal is corrected.

1.8 Example of Luminance Distribution FIG. 7 is a diagram showing an example of the luminance value distribution in the LED display unit provided in the LED display device of the first embodiment when correction for making pixel defects inconspicuous is not performed. Is. FIG. 8 is a diagram showing an example of the distribution of the luminance value in the LED display unit provided in the LED display device of the first embodiment when the correction for making the pixel defects inconspicuous is performed.

In each of the figures of FIGS. 7 and 8, the brightness value of each LED 140 is superimposed on each LED 140 included in the plurality of LED 130s.

When the correction for making the pixel defect 160 inconspicuous is not performed, the brightness value of the third LED 173 other than the failed first LED 171 is corrected by using the brightness correction factor θ = 1. In this case, for example, as shown in FIG. 7, the failed first LED 171 has a brightness value of 0. Further, the third LED 173 other than the failed first LED 171 has a target luminance value 70.

On the other hand, when the correction for making the pixel defect 160 inconspicuous is performed, the brightness values of the failed first LED 171 and the fourth LED 174 other than the second LED 172 adjacent to the first LED 171 are the brightness values. It is corrected using the correction factor θ = 1. Further, the brightness value of the LED 172a included in the second LED 172 and arranged above, below, left or right of the first LED 171 is corrected by using the brightness correction factor θ1. Further, the brightness value of the LED 172b included in the second LED 172 and arranged at the upper left, upper right, lower left or lower right of the first LED 171 is corrected by using the brightness correction factor θ2. The correction is performed so that the brightness of the second LED 172 becomes high. Therefore, the luminance correction factors θ1 and θ2 are larger than 1 (θ1> 1 and θ2> 1). Further, the distance from the center of the first LED 171 to the LED 172b is longer than the distance from the center of the first LED 171 to the LED 172a. Therefore, the luminance correction factor θ2 is smaller than the luminance correction factor θ1 (θ1> θ2). Therefore, the luminance correction factors θ1 and θ2 satisfy the relationship represented by θ1> θ2> 1. For example, the luminance correction factor θ1 is 1.1. The luminance correction factor θ2 is 1.05. In this case, for example, as shown in FIG. 8, the failed first LED 171 has a brightness value of 0. Further, the fourth LED 174 other than the failed first LED 171 and the second LED 172 adjacent to the first LED 171 has the same target luminance value 70 as the above-mentioned target luminance value 70. Further, the LED 172a included in the second LED 172 has a luminance value 77 obtained by multiplying the luminance value 70 by the luminance correction factor θ1. Further, the LED 172b included in the second LED 172 has a luminance value 74 obtained by multiplying the luminance value 70 by the luminance correction factor θ2.

According to the distribution of the luminance values illustrated in FIG. 8, the second LED 172 adjacent to the first luminance LED 171 having the luminance value 0 has a

luminance value

77 or 74 higher than the target luminance value 70. Therefore, the pixel defect 160 caused by the first LED 171 is inconspicuous. As a result, pixel defect noise caused by the failure of the first LED 171 can be reduced, and an image appearing to have uniform brightness can be displayed on the LED display unit 105.

1.9 Effect of the Invention of the First Embodiment According to the invention of the first embodiment, the LED display device 1 includes a brightness correction unit 103 and a failure detection unit 106. Therefore, the video signal is corrected to make the brightness of the LED uniform. Further, when the first LED 171 fails, the video signal is corrected to change the brightness of the second LED 172. Therefore, even if the first LED 171 fails, the LED display device 1 capable of displaying an image in which the pixel defect 160 caused by the failure of the first LED 171 is inconspicuous and appears to have uniform brightness is provided. be able to.

Further, according to the invention of the first embodiment, a correction for making the brightness of a plurality of LEDs 130 uniform, a correction for compensating for a decrease in the brightness of each LED 140 due to aged deterioration, etc. The above-mentioned correction that makes the pixel defect 160 inconspicuous can be used in combination.

In the technique contrasted with the invention of the first embodiment, when the LED display device incorporated in the display system fails, the operation of the display system is interrupted, and the operation of the display system is interrupted while the failure occurs. The LED display device is repaired. Therefore, in the present technology, for example, when a failure of the LED provided in the LED display device is detected, the operator of the display system is notified or warned of the failure of the LED.

On the other hand, the invention of the first embodiment is described even when the LED display device 1 fails when the LED display device 1 is incorporated in a display system such as a display system used for monitoring applications which is required to operate 24 hours a day. , It is based on the original idea that the operation of the display system can be continued.

2 Embodiment 2
FIG. 1 is also a diagram illustrating the LED display device of the second embodiment. FIG. 2 is also a plan view schematically showing an LED display unit provided in the LED display device of the second embodiment. FIG. 3 is also a plan view schematically showing one pixel provided in the LED display device of the second embodiment. FIG. 4 is also a timing chart for explaining the PWM drive performed in the LED display device of the second embodiment. FIG. 6 is also a flowchart showing the operation of the LED display device according to the second embodiment.

The LED display device 2 of the second embodiment is different from the LED display device 1 of the first embodiment mainly in the following points. Regarding points not described below, the same configuration as that adopted in the LED display device 1 of the first embodiment is also adopted in the LED display device 2 of the second embodiment.

FIG. 9 is a diagram showing an example of the distribution of the luminance value in the LED display unit provided in the LED display device of the second embodiment when the correction for making the pixel defects inconspicuous is performed. FIG. 10 is a diagram showing an example of the distribution of the luminance correction factor θ in the LED display unit provided in the LED display device of the second embodiment when the correction for making the pixel defects inconspicuous is performed.

In FIG. 9, the brightness value of each LED 140 is superimposed on each LED 140 included in the plurality of LED 130s. In FIG. 10, the brightness correction factor θ used for correcting the brightness value of each LED 140 is superimposed on each LED 140.

The correction for making the pixel defect 160 inconspicuous in the LED display device 1 of the first embodiment is a correction performed when the first LED 171 including one LED fails, as shown in FIG. .. On the other hand, the correction for making the pixel defect 160 inconspicuous in the LED display device 2 of the second embodiment includes two

LEDs

171a and 171b that are close to each other as shown in FIGS. 9 and 10. This is a correction performed when the LED 171 of 1 fails.

The plurality of LEDs 130 make the first LED 171 and the pixel defect 160, which cause the pixel defect 160, inconspicuous, as shown in FIGS. 9 and 10, when the first LED 171 included in the plurality of LED 130 fails. Includes a second LED 172 that is subject to correction.

When correction is performed to make the pixel defect 160 inconspicuous, the brightness values of the failed first LED 171 and the fourth LED 174 other than the second LED 172 adjacent to the first LED 171 have a brightness correction factor θ = 1. Is corrected using. Further, the brightness of the LED 172c included in the second LED 172 and arranged above, below, left or right of the LED 171a, and the brightness of the LED 172d included in the second LED 172 and arranged above, below, left or right of the LED 171b. The value is corrected using the luminance correction factor θ1. Further, the LED 172e included in the second LED 172 and arranged at the upper left, upper right, lower left or lower right of the LED 171a, and the LED 172f included in the second LED 172 and arranged at the upper left, upper right, lower left or lower right of the LED 171b. The brightness value of is corrected by using the brightness correction factor θ2. The brightness value of the LED 172g arranged above, below, left or right of the LED 171a and above, below, left or right of the LED 171b is the product θ1 * θ1 of the brightness correction factor θ1 and the brightness correction factor θ1. Is corrected using. The correction is performed so that the brightness of the second LED 172 becomes high. Therefore, the luminance correction factors θ1 and θ2 are larger than 1 (θ1> 1 and θ2> 1). The distance from the center of the LED 171a to the LED 172e is longer than the distance from the center of the LED 171a to the LED 172c, and the distance from the center of the LED 171b to the LED 172f is longer than the distance from the center of the LED 171b to the LED 172d. Therefore, the luminance correction factor θ2 is smaller than the luminance correction factor θ1 (θ1> θ2). Therefore, the luminance correction factors θ1 and θ2 satisfy the relationship represented by θ1> θ2> 1. For example, the luminance correction factor θ1 is 1.1. The luminance correction factor θ2 is 1.05. In this case, for example, as shown in FIG. 9, the failed first LED 171 has a brightness value of 0. Further, the failed first LED 171 and the LED 174 other than the second LED 172 adjacent to the first LED 171 have a target luminance value 70. Further, the LEDs 172h arranged above, below, left or right of one of the

LEDs

171a and 171b have a brightness value 77 obtained by multiplying the brightness value 70 by the brightness correction factor θ1. Further, the

LEDs

172e and 172f arranged at the upper left, upper right, lower left or lower right of one of the

LEDs

171a and 171b have a luminance value 74 obtained by multiplying the luminance value 70 by the luminance correction factor θ2. Further, the LED 172g arranged above, below, left or right of the LED 171a and above, below, left or right of the LED 171b has a brightness value 70 and a product θ1 of the brightness correction factor θ1 and the brightness correction value θ1. It has a brightness value of 85 obtained by multiplying by * θ1.

According to the distribution of the brightness values illustrated in FIG. 9, the second LED 172 adjacent to the first LED 171 having the brightness value 0 has a

brightness value

77, 74 or 85 higher than the target brightness value 70. Therefore, the pixel defect 160 caused by the first LED 171 having a brightness value of 0 is not conspicuous. As a result, pixel defect noise caused by the failure of the first LED 171 can be reduced, and an image appearing to have uniform brightness can be displayed on the LED display unit 105.

2.1 Effect of the Invention of the Second Embodiment According to the invention of the second embodiment, the pixel defect 160 caused by the failure of the first LED 171 is inconspicuous and the brightness is uniform as in the invention of the first embodiment. It is possible to provide an LED display device 2 capable of displaying an image that appears to be possessed.

In addition, according to the invention of the second embodiment, it is possible to provide the LED display device 2 in which the pixel defect 160 caused by the failure of the two

LEDs

171a and 171b is inconspicuous even when the two

LEDs

171a and 171b fail.

3 Modifications In the first and second embodiments, the second LED 172 to be corrected to make the pixel defect 160 inconspicuous is an LED adjacent to the failed first LED 171. However, the second LED 172 may include an LED other than the LED adjacent to the failed first LED 171. For example, the second LED 172 may include a few LEDs away from the failed first LED 171.

In the first and second embodiments, the luminance correction factor θ1 used for correcting the luminance values of the

LEDs

172a, 172c and 172d arranged above, below, left or right of the failed first LED 171 has failed. The brightness correction factors θ2 used for correcting the brightness values of the

LEDs

172b, 172e and 172f arranged at the upper left, upper right, lower left or lower right of the first LED 171 are different from each other. The brightness correction factor θ used for correcting the brightness value of the second LED 172 may be a brightness correction factor different from this. For example, the brightness correction factors used to correct the brightness value of the second LED 172 may all be the same.

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

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

1, 2, LED display device, 103 brightness correction unit, 104 drive unit, 105 LED display unit, 106 failure detection unit, 107 correction coefficient calculation unit, 130 multiple LEDs, 140 each LED, 171 first LED, 172 second LED, 160 pixel defect.

Claims

An LED display unit (105) including a plurality of LEDs (130) arranged in a matrix, and
A failure detection unit (106) for detecting a failure of each LED (140) included in the plurality of LEDs (130), and a failure detection unit (106).
The video signal is corrected so that the brightness of the two or more LEDs (174) included in the plurality of LEDs (130) is uniform, the video signal is corrected according to the brightness correction coefficient, and the corrected video signal is obtained. The output brightness correction unit (103) and
When a failure of the first LED (171) included in the plurality of LEDs (130) is detected by the failure detection unit (106), the first LED included in the plurality of LEDs (130). A correction coefficient calculation unit (107) that calculates the brightness correction coefficient so that the brightness of the second LED (172) different from (171) changes.
A drive unit (104) that drives the plurality of LEDs (130) according to the corrected video signal, and
LED display devices (1, 2).
The LED display device (1, 2) according to claim 1, wherein the second LED (172) includes an LED adjacent to the first LED (171).
The correction coefficient calculation unit (107) increases the brightness of the second LED (172) when the failure of the first LED (171) is detected by the failure detection unit (106). The LED display device (1, 2) according to claim 1 or 2, which calculates the brightness correction coefficient.
The two or more LEDs (174) are LEDs other than the first LED (171) and the second LED (172) included in the plurality of LEDs (130).
The video signal includes a first signal indicating the brightness of the two or more LEDs (174) and a second signal indicating the brightness of the second LED (172).
The brightness correction unit (103) corrects the first signal so that the brightness of the two or more LEDs (174) becomes uniform, and corrects the second signal according to the brightness correction coefficient. The LED display device (1, 2) according to any one of Items 1 to 3.