JP6742562B1 - LED display device and brightness correction method for LED display device - Google Patents

Abstract

While suppressing power consumption of the LED display device, deterioration of image quality of the LED display device is suppressed. At that time, the image quality of the LED display device is stabilized. The LED display device includes a brightness information calculation unit, a calculation unit, a display unit, a correction processing unit, and a drive unit. The brightness information calculation unit calculates brightness information indicating the brightness of each frame from the video signal. The calculation unit determines the drive current value based on a plurality of brightness information indicating the brightness of each of the plurality of frames so that the power consumption of the LED display device is equal to or less than the set upper limit value, and the brightness information and the drive current value are determined. The brightness correction coefficient is calculated based on The display unit includes a plurality of LED display elements. The correction processing unit corrects the video signal with the brightness correction coefficient to obtain the corrected video signal. The drive unit drives the plurality of LED display elements with a drive current value according to the corrected video signal.

Description

The present invention relates to an LED display device and a brightness correction method for the LED display device.

A light emitting diode (LED) display device includes a plurality of LEDs arranged in a plane. LED display devices have come to be widely used for displaying advertisements indoors and outdoors along with technological development of LEDs and cost reduction.

LED display devices were once mainly used to display moving images such as natural images and animations. However, recently, since the pixel pitch of the LED display device has become narrower and the viewing distance of the LED display device has become shorter, the LED display device has been used for displaying a conference image, a monitoring image, etc. indoors. Is becoming.

In the display device described in Patent Document 1, the panel current flowing in all pixels when displaying the display panel is predicted based on the image data (paragraph 0012). If the predicted panel current exceeds the set value, the set contrast or brightness is corrected (paragraph 0015). If the predicted panel current is small, the contrast or brightness is set as set (paragraph 0016). As a result, the actual panel current is suppressed below the maximum panel current (paragraphs 0015-0016).

JP, 2004-309810, A

When power control similar to the power control adopted in the display device described in Patent Document 1 is adopted in a pulse width modulation (PWM) type LED display device, the LED display device is consumed. When image signal processing such as correction of contrast and brightness is performed to suppress power, image quality is deteriorated such as reduction of dynamic range of displayed image.

The present invention has been made in view of this problem. An object of the present invention is to suppress deterioration of image quality of an LED display device while suppressing power consumption of the LED display device. Another object of the present invention is to stabilize the image quality of the LED display device at that time.

The present invention relates to an LED display device.

The LED display device includes a brightness information calculation unit, a calculation unit, a display unit, a correction processing unit, and a drive unit.

The brightness information calculation unit calculates brightness information indicating the brightness of each frame from the video signal.

The calculation unit determines the drive current value based on a plurality of pieces of brightness information indicating the brightness of each of the plurality of frames so that the power consumption of the LED display device is equal to or less than the set upper limit value. The brightness correction coefficient is calculated based on

The display unit includes a plurality of LED display elements.

The correction processing unit corrects the video signal with the brightness correction coefficient to obtain the corrected video signal.

The drive unit drives the plurality of LED display elements with a drive current value according to the corrected video signal.

The present invention also relates to a brightness correction method for an LED display device.

According to the present invention, the drive current value is determined and the brightness correction coefficient is calculated so that the power consumption of the LED display device is equal to or less than the set upper limit value. As a result, the power consumption of the LED display device can be set to the set upper limit value or less.

Further, according to the present invention, the luminance information is calculated from the video signal. Further, the drive current value is determined based on the calculated brightness information. Further, the brightness correction coefficient is calculated based on the determined drive current value. Thus, while driving the plurality of LED display elements with a drive current value that increases the luminous efficiency of the plurality of LED display elements, it is possible to suppress deterioration of image quality of the LED display device related to the brightness of the plurality of LED display elements. it can.

Further, according to the present invention, the luminance information indicating the luminance of each frame is calculated from the video signal. Further, the drive current value is determined based on the calculated plurality of pieces of brightness information indicating the brightness of each of the plurality of frames. Thereby, the image quality of the LED display device related to the brightness of the plurality of LED display elements can be stabilized.

As a result, according to the present invention, it is possible to suppress the deterioration of the image quality of the LED display device while suppressing the power consumption of the LED display device. Further, at that time, the image quality of the LED display device can be stabilized.

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

1 is a block diagram illustrating a functional configuration of a light emitting diode (LED) display device according to a first embodiment. FIG. 3 is a block diagram illustrating a hardware configuration of the LED display device according to the first embodiment. FIG. 5 is a diagram schematically illustrating another example of the video display area of the LED display device of the first embodiment. 4 is a timing chart illustrating PWM driving performed by the LED display device according to the first embodiment. 4 is a graph showing an example of current-luminance characteristics showing the relationship between the drive current flowing through the LED provided in the LED display device of Embodiment 1 and the luminance of the LED. 3 is a flowchart illustrating a flow of controlling the brightness of the LED display element performed by the LED display device of the first embodiment. 3 is a flowchart illustrating a flow of controlling the brightness of the LED display element performed by the LED display device of the first embodiment. 6 is a graph showing the relationship between the average pixel value AveRGB calculated by the LED display device of the first embodiment and the first brightness correction coefficient calculated by the LED display device. 6 is a graph showing the relationship between the average pixel value AveRGB calculated by the LED display device of the first embodiment and the second luminance correction coefficient calculated by the LED display device. 7 is a timing chart for explaining the timing when the LED display device according to the first embodiment and the modification thereof determines and calculates the drive current value and the brightness correction coefficient.

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

The LED display device 1 according to the first embodiment shown in FIG. 1 displays an image according to an image signal input from the outside. Further, the LED display device 1 performs power saving control so that the power consumption of the LED display device 1 becomes equal to or less than the power saving control target value PWt input from the outside.

As shown in FIG. 1, the LED display device 1 includes a display unit 11, a video signal input unit 12, a power-saving control target value input unit 13, a video signal processing unit 14, a brightness information calculation unit 15, a calculation unit 16, A brightness information storage unit 17, a correction processing unit 18, and a drive unit 19 are provided.

The display unit 11 includes a plurality of LED display elements. Each of the plurality of LED display elements becomes a pixel.

A video signal is input to the video signal input unit 12 from the outside.

A power saving control target value PWt is input to the power saving control target value input unit 13 from the outside. The power saving control target value PWt that is input is the upper limit value of the power consumption of the LED display device 1. The power saving control target value PWt is a target value of the power consumption of the LED display device 1 when the LED display device 1 is made to perform the power saving operation, which is input by the user. The input power saving control target value PWt is set as the upper limit value of the power consumption of the LED display device 1 for performing the power saving control.

The video signal processing unit 14 processes the video signal input to the video signal input unit 12. The processing performed includes image processing such as gamma correction. The processed video signal includes a plurality of pixel values respectively indicating the brightness of the plurality of LED display elements included in the display unit 11.

The brightness information calculator 15 calculates brightness information indicating the brightness of each frame from the video signal processed by the video signal processor 14. The calculated brightness information is the sum or average of a plurality of pixel values included in the video signal, and indicates the brightness of the video displayed in the video display area of the display unit 11. In the first embodiment, the calculated brightness information is the average of a plurality of pixel values included in the video signal. Further, the brightness information calculation unit 15 causes the brightness information storage unit 17 to store the calculated brightness information. As a result, the brightness information storage unit 17 stores a plurality of brightness information indicating the brightness of each of the plurality of frames.

The calculation unit 16 determines the drive current value and the brightness correction coefficient so that the power consumption of the LED display device 1 is equal to or less than the set upper limit value PWt, and calculates the determined drive current value and the brightness correction coefficient. Therefore, the calculation unit 16 includes a brightness correction control unit 21, a drive current value calculation unit 22, and a brightness correction coefficient calculation unit 23, as shown in FIG.

The brightness correction control unit 21 performs power saving control. At this time, the brightness correction control unit 21 corrects the drive current value and the brightness based on the set upper limit PWt of the power consumption of the LED display device 1 and the plurality of brightness information stored in the brightness information storage unit 17. Determine the coefficient.

The brightness correction control unit 21 determines the drive current value based on the plurality of brightness information stored in the brightness information storage unit 17. In the first embodiment, two types of drive current values, which are the first drive current value 31 and the second drive current value 32, are preset. The brightness correction control unit 21 determines the drive current value by selecting the drive current value from two types of drive current values including the first drive current value 31 and the second drive current value 32. The second drive current value 32 is smaller than the first drive current value 31. The first drive current value 31 is selected when the brightness of the plurality of LED display elements included in the display unit 11 is low, the power consumption of the LED display device 1 is low, and normal control is performed. The second drive current value 32 is selected when the plurality of LED display elements included in the display unit 11 have high brightness, the LED display device 1 has large power consumption, and power saving control is performed. The brightness correction controller 21 may determine the drive current value by selecting the drive current value from three or more types of drive current values. The brightness correction control unit 21 may determine the drive current value by setting the drive current value using a special function in order to seamlessly perform the power saving control.

Further, the brightness correction control unit 21 determines the brightness correction coefficient based on the determined drive current value. In the first embodiment, the brightness correction control unit 21 selects the brightness correction coefficient from the two types of brightness correction coefficients consisting of the first brightness correction coefficient 41 and the second brightness correction coefficient 42. To decide. The first brightness correction coefficient 41 and the second brightness correction coefficient 42 correspond to the first drive current value 31 and the second drive current value 32, respectively. The brightness correction control unit 21 also selects a brightness correction coefficient corresponding to the selected drive current value. Therefore, when the first drive current value 31 is selected, the brightness correction control unit 21 selects the first brightness correction coefficient 41. In addition, the brightness correction control unit 21 selects the second brightness correction coefficient 42 when the second drive current value 32 is selected. When the brightness correction control unit 21 determines a drive current value by selecting a drive current value from three or more kinds of drive current values, the brightness correction control unit 21 corresponds to three or more kinds of drive current values. The brightness correction coefficient may be determined by selecting the brightness correction coefficient from among the brightness correction coefficients of more than one type. The brightness correction control unit 21 may determine the brightness correction coefficient by setting the brightness correction coefficient using a special function in order to seamlessly perform the power saving control.

The drive current value calculation unit 22 calculates the drive current value to be passed to the drive unit 19, based on the drive current value determined by the brightness correction control unit 21. The drive current value passed to the drive unit 19 is used by the drive unit 19 to drive the plurality of LED display elements included in the display unit 11.

The brightness correction coefficient calculation unit 23 calculates the brightness correction coefficient to be passed to the correction processing unit 18, based on the drive current value and the brightness correction coefficient determined by the brightness correction control unit 21. The brightness correction coefficient calculation unit 23 calculates the brightness correction coefficient based on the brightness information indicating the brightness of each frame calculated by the brightness information calculation unit 15. The brightness correction coefficient passed to the correction processing unit 18 is used by the correction processing unit 18 to correct the video signal processed by the video signal processing unit 14.

The correction processing unit 18 corrects the video signal processed by the video signal processing unit 14 using the brightness correction coefficient calculated by the calculation unit 16 to obtain a corrected video signal. At that time, the correction processing unit 18 corrects the brightness of the video image represented by the video signal by multiplying the pixel value included in the video signal by the brightness correction coefficient.

The drive unit 19 drives the plurality of LED display elements included in the display unit 11 with the drive current value determined by the calculation unit 16 according to the video signal corrected by the correction processing unit 18. At that time, the drive unit 19 performs PWM drive for supplying a pulse width modulation (PWM) signal corresponding to the drive current value and the pixel value included in the video signal to the LED display element.

Each of the plurality of LED display elements included in the display unit 11 emits light with a brightness according to the PWM signal supplied by the drive unit 19. As a result, the display unit 11 displays an image according to the drive current value determined by the calculation unit 16 and the image signal corrected by the correction processing unit 18.

With these, the calculation unit 16, the correction processing unit 18, and the drive unit 19 set the brightness and dynamic range of the image displayed on the display unit 11 so that the power consumption of the LED display device 1 is equal to or less than the set upper limit value PWt. The process of correcting the signal can be performed on the video signal processed by the video signal processing unit 14.

1.2 Hardware Configuration of LED Display Device FIG. 2 is a block diagram illustrating the hardware configuration of the LED display device according to the first embodiment.

As shown in FIG. 2, the LED display device 1 includes the above-described display unit 11, video signal input unit 12, video signal processing unit 14, correction processing unit 18, and driving unit 19. The LED display device 1 also includes an input interface (I/F) 51, a memory 52, a central processing unit (CPU) 53, a network I/F 54, and a data bus 55.

The display unit 11 includes the plurality of LED display elements 61 as described above. The display unit 11 has a video display area 11a. In the video display area 11a, each frame constituting the video represented by the video signal corrected by the correction processing unit 18 is sequentially displayed. The plurality of LED display elements 61 are arranged in a matrix in the video display area 11a. In the first embodiment, each of the plurality of LED display elements 61 includes a plurality of LEDs each having a plurality of different emission colors. In the first embodiment, the plurality of emission colors different from each other are red (R), green (G) and blue (B). Each of the plurality of LED display elements 61 constitutes a pixel. FIG. 2 shows a case in which the plurality of pixels each constituted by the plurality of LED display elements 61 are 16 pixels of 4 pixels in the horizontal direction×4 pixels in the vertical direction. Each of the plurality of LED display elements 61 has a pixel value. The pixel value corresponds to the gradation of the luminance of the image represented by the image signal. In the first embodiment, each of the plurality of LEDs included in each of the plurality of LED display elements 61 also has a pixel value.

The video signal input unit 12 is composed of a video signal input circuit to which a video signal is input.

The video signal processing unit 14 is configured by a video signal processing circuit that processes the video signal input to the video signal input unit 12. The video signal processing circuit adjusts the amplitude, waveform, etc. of the video signal when processing the video signal.

The correction processing unit 18 includes a correction processing circuit that corrects the video signal processed by the video signal processing unit 14. The correction processing circuit adjusts the amplitude and the like of the video signal when correcting the video signal.

The drive unit 19 is configured by a drive circuit that drives the plurality of LED display elements 61. The drive circuit, when driving the plurality of LED display elements 61, generates a PWM signal to be supplied to the plurality of LED display elements 61.

To the input I/F 51, a signal indicating the content of an operation performed on an operating device such as an external remote controller, setting information, and the like are input. The input setting information includes the power saving control target value PWt.

The memory 52 includes a temporary storage memory and a non-volatile memory. The temporary storage memory temporarily stores the image data included in the video signal input to the video signal input unit 12 and the calculation data such as the brightness information calculated by the brightness information calculation unit 15. The temporary storage memory is a random access memory (RAM) or the like. The non-volatile memory stores a control program, an initial setting value, a power saving control target value PWt, and the like. The non-volatile memory is a flash memory or the like.

The CPU 53 executes the control program stored in the memory 52. As a result, the CPU 53 performs calculation and processing according to the control program and controls the entire LED display device 1.

The network I/F 54 transmits/receives data to/from an external device, another LED display device that constitutes a large screen together with the LED display device 1, and the like.

The data bus 55 transmits data transmitted/received between elements included in the LED display device 1.

The power saving control target value input unit 13 shown in FIG. 1 is configured by an input I/F 51. The brightness information calculator 15, the brightness correction controller 21, the drive current value calculator 22, and the brightness correction coefficient calculator 23 illustrated in FIG. 1 are configured by the CPU 53. The processing performed by the luminance information calculation unit 15, the luminance correction control unit 21, the drive current value calculation unit 22, and the luminance correction coefficient calculation unit 23 is performed by the CPU 53 executing the control program stored in the memory 52. The brightness information storage unit 17 shown in FIG. 1 is configured by the memory 52.

All or part of the video signal processing unit 14 and the correction processing unit 18 may be configured by the CPU 53. That is, all or part of the processing performed by the video signal processing unit 14 and the correction processing unit 18 may be performed by the CPU 53 executing the control program stored in the memory 52.

1.3 Another Example of Image Display Area FIG. 3 is a diagram schematically showing another example of the image display area of the LED display device of the first embodiment.

The video display area 11a illustrated in FIG. 3 is a video display area when the display unit 11 has an input resolution of 1920 pixels in the horizontal direction×1080 pixels in the vertical direction. Therefore, in the image display area 11a shown in FIG. 3, 1920 LED elements in the horizontal direction and 1080 LED elements in the vertical direction are arranged.

1.4 LED Brightness Control Method FIG. 4 is a timing chart for explaining PWM drive performed by the LED display device according to the first embodiment. FIG. 4A illustrates a waveform of a signal including a pulse that is emitted each time the basic period of PWM driving elapses. 4(b) and 4(c) illustrate the current waveform of the PWM signal supplied to the LED.

The basic cycle of the PWM drive shown in FIG. 4A is one frame period of the video signal corrected by the correction processing unit 18. The current waveform of the PWM signal illustrated in FIGS. 4B and 4C includes a current pulse. The current pulse gives the PWM signal a pulse height corresponding to the drive current value calculated by the drive current value calculation unit 22 and a duty ratio according to the pixel value included in the video signal corrected by the correction processing unit 18. It has a pulse width. When the PWM signal having the current waveforms shown in FIGS. 4B and 4C is supplied to the LED, the drive current having the drive current value flows to the LED during the ON period having the pulse width. .. The pulse width is one frame period or less. The current pulse shown in FIG. 4(b) has a pulse width PWM1 that gives a duty ratio of 100% to the PWM signal. The current pulse shown in FIG. 4(c) has a pulse width PWM2 that gives the PWM signal a duty ratio of 75%.

The energization time of the LED in one frame period becomes shorter as the duty ratio of the PWM signal supplied to the LED becomes smaller. Therefore, the average luminance of the LED in one frame period becomes lower as the duty ratio of the PWM signal supplied to the LED becomes smaller. For example, when the PWM signal having the duty ratio of 75% shown in FIG. 4C is supplied to the LED, the energization time in one frame period of the LED is 100% duty ratio shown in FIG. 4B. Will be shorter than if the PWM signal with is supplied to the LED. Further, when the PWM signal having the duty ratio of 75% shown in FIG. 4C is supplied to the LED, the average luminance in one frame period of the LED is 100% duty ratio shown in FIG. 4B. Will be lower than that when a PWM signal is supplied to the LED. Therefore, by changing the duty ratio of the PWM signal supplied to the LED, the average luminance of the LED in one frame period can be adjusted. Further, the smaller the duty ratio of the PWM signal supplied to the LED, the shorter the energization time of the LED in one frame period. Therefore, the power consumption of the LED in one frame period is the duty ratio of the PWM signal supplied to the LED. The smaller it gets, the smaller it gets. For example, when the PWM signal having the duty ratio of 75% shown in FIG. 4C is supplied to the LED, the power consumption of the LED in one frame period is 100% duty ratio shown in FIG. 4B. Will be smaller than if the PWM signal with?

As described above, the average luminance of the LED in one frame period becomes lower as the duty ratio of the PWM signal supplied to the LED becomes smaller. Further, the power consumption of the LED in one frame period becomes smaller as the duty ratio of the PWM signal supplied to the LED becomes smaller. Therefore, the lower the brightness of the LED indicated by the pixel value included in the video signal corrected by the correction processing unit 18, the smaller the duty ratio of the PWM signal supplied to the LED, and the power consumption of the LED in one frame period. Get smaller. On the other hand, as the brightness of the LED indicated by the pixel value included in the video signal increases, the duty ratio of the PWM signal supplied to the LED increases, and the power consumption of the LED in one frame period increases. The power consumption of the LED in one frame period is approximately proportional to the duty ratio of the PWM signal. Therefore, the power consumption of the LED in one frame period when the duty ratio of the PWM signal supplied to the LED is 75% is about that of the power consumption when the duty ratio of the PWM signal supplied to the LED is 100%. It becomes 75%.

1.5 Relationship between Driving Current and Luminous Efficiency FIG. 5 is a graph showing an example of current-luminance characteristics showing a relationship between the driving current flowing through the LED included in the LED display device of the first embodiment and the luminance of the LED. is there.

The brightness of the LED increases as the drive current flowing through the LED increases, as in the drive current brightness characteristic IY shown in FIG. Further, the power consumption of the LED increases as the drive current flowing through the LED increases. Therefore, the power consumption of the LED increases as the brightness of the LED increases. In addition, the brightness of the image displayed in the image display area 11a increases as the drive current flowing through the LED included in the display unit 11 increases. In addition, the power consumption of the display unit 11 increases as the drive current flowing through the LEDs included in the display unit 11 increases.

On the other hand, the brightness of the LED is approximately proportional to the drive current flowing through the LED, but is saturated as the drive current flowing through the LED approaches the maximum drive current. Therefore, the luminous efficiency of the LED decreases as the drive current flowing through the LED approaches the maximum drive current.

Therefore, in order to increase the brightness of the image displayed in the image display area 11a, it is necessary to increase the duty ratio of the PWM signal supplied to the LED rather than increase the drive current flowing to the LED. The power can be reduced.

1.6 Flow of Controlling Luminance of LED Display Element FIGS. 6 and 7 are flowcharts illustrating a flow of controlling luminance of the LED display element performed by the LED display device according to the first embodiment.

When the LED display device 1 controls the brightness of the plurality of LED display elements 61, steps S01 to S17 shown in FIGS. 6 and 7 are executed. In steps S01 to S17, when the video represented by the input video signal is displayed in the video display area 11a, the brightness of the displayed video is controlled so that the power consumption of the LED display device 1 is suppressed. And/or the dynamic range is corrected.

In steps S01 to S17 illustrated in FIGS. 6 and 7, the average brightness value AveRGB of each frame is used as the brightness information indicating the brightness of each frame. The average luminance value AveRGB of each frame indicates the average of a plurality of pixel values included in the video signal processed by the video signal processing unit 14. Further, m pieces of average pixel values AveRGB respectively showing the brightness of the latest m consecutive frames are used as a plurality of pieces of brightness information respectively showing the brightness of a plurality of frames. m is an integer of 2 or more.

In step S01, the power saving control target value PWt is input to the power saving control target value input unit 13. The input power saving control target value PWt is set as the upper limit value of the power consumption of the LED display device 1 for performing the power saving control.

In subsequent step S02, the brightness correction control unit 21 sets a threshold value Tp for calculating the brightness correction coefficient based on the set upper limit value PWt of the power consumption of the LED display device 1.

In the following step S03, the video signal is input to the video signal input unit 12. Also, the video signal processing unit 14 processes the input video signal.

In subsequent step S04, the brightness information calculation unit 15 calculates the average pixel value AveRGB from the video signal processed by the video signal processing unit 14.

In subsequent step S05, the brightness information calculation unit 15 stores the calculated average pixel value AveRGB in the brightness information storage unit 17.

The total number of pixels indicating the number of the plurality of LED display elements 61 is num, and when each frame is displayed, the R LED and G of the i-th LED display element included in the plurality of LED display elements 61 are provided. When the pixel values indicating the brightness of the LEDs of LED and B are Ri, Gi, and Bi, respectively, the average pixel value AveRGB is represented by (Equation 1).

The average pixel value AveRGB represented by (Equation 1) indicates the brightness per LED display element in each frame.

In the first embodiment, each of the pixel values Ri, Gi and Bi has a bit length of 8 bits and has 256 gradations. Therefore, the maximum pixel value that the average pixel value AveRGB can take is 255. The minimum pixel value that the average pixel value AveRGB can take is 0.

Further, the power consumption of the LED display device 1 when the average pixel value AveRGB takes the maximum pixel value 255 is PWaall, and the power consumption of the LED display device 1 when the average pixel value AveRGB takes the minimum pixel value 0 is PW0. In this case, the threshold value Tp for calculating the brightness correction coefficient satisfies (Equation 2).

The brightness information storage unit 17 repeats storing the average pixel value AveRGB indicating the brightness of each frame in the brightness information storage unit 17, so that the brightness information storage unit 17 displays m values indicating the brightness of m consecutive frames. The average pixel values AveRGB are stored.

In subsequent step S 06, the brightness correction control unit 21 reads the average pixel value AveRGB from the brightness information storage unit 17. Further, the brightness correction control unit 21 determines whether or not the average pixel value AveRGB is larger than the threshold value Tp for calculating the set brightness correction coefficient. When it is determined that the average pixel value AveRGB is less than or equal to the threshold value Tp, step S07 is executed and then step S10 is executed. When it is determined that the average pixel value AveRGB is larger than the threshold value Tp, step S10 is executed after steps S08 and S09 are executed.

In step S07, the brightness correction control unit 21 instructs the brightness correction coefficient calculation unit 23 to set the first brightness correction coefficient 41 to 1.0.

In step S08, the brightness correction control unit 21 instructs the brightness correction coefficient calculation unit 23 to set the first brightness correction coefficient 41 to a value smaller than 1.0.

In the following step S09, the brightness correction coefficient calculation unit 23 sets the first brightness correction coefficient 41 based on the read average pixel value AveRGB so that the first brightness correction coefficient 41 becomes a value smaller than 1.0. Is calculated.

The first brightness correction coefficient 41 is multiplied by the pixel value indicating the brightness of the plurality of LED display elements 61, as described below. Therefore, when the first brightness correction coefficient is set to 1.0, the plurality of LED displays when the video signal processed by the video signal processing unit 14 is corrected by the first brightness correction coefficient 41. The brightness of the element 61 does not change from the brightness of the plurality of LED display elements 61 when the video signal is not corrected by the first brightness correction coefficient 41. When the first brightness correction coefficient 41 is set to a value smaller than 1.0, the brightness of the plurality of LED display elements 61 when the video signal is corrected by the first brightness correction coefficient 41 is The luminance is lower than the luminance of the plurality of LED display elements 61 when the video signal is not corrected by the first luminance correction coefficient 41.

When the power consumption of the LED display device 1 when the average pixel value AveRGB takes the maximum pixel value 255 is PWaall and when the power consumption of the LED display device 1 when the average pixel value AveRGB takes the minimum pixel value 0 is PW0 , The power consumption PWa of the LED display device 1 is represented by (Equation 3).

From (Equation 2) and (Equation 3), when the average pixel value AveRGB is equal to or less than the threshold value Tp for calculating the brightness correction coefficient, the power consumption PWa of the LED display device 1 is equal to or less than the power saving control target value PWt. I can understand that. Further, from (Equation 2) and (Equation 3), when the average pixel value AveRGB is larger than the threshold value Tp, the power consumption PWa of the LED display device 1 is the power-saving control target value PWt unless the power-saving control is performed. You can understand that it will be larger. Therefore, in the power saving control, when the average pixel value AveRGB is larger than the threshold value Tp, the first brightness correction coefficient 41 is set to a value smaller than 1.0 to reduce the brightness of the plurality of LED display elements 61. The process includes setting the power consumption PWa of the LED display device 1 to be equal to or less than the power saving control target value PWt. As a result, the power consumption PWa of the LED display device 1 can always be set to the power saving control target value PWt or less.

FIG. 8 is a graph showing the relationship between the average pixel value AveRGB calculated by the LED display device of the first embodiment and the first brightness correction coefficient calculated by the LED display device. The average pixel value AveRGB is plotted on the horizontal axis of the graph shown in FIG. The first brightness correction coefficient 41 is plotted on the vertical axis of the graph shown in FIG.

When the average pixel value AveRGB is less than or equal to the threshold value Tp for calculating the brightness correction coefficient, the brightness correction control unit 21 sets the first brightness correction coefficient 41 to 1.0 as illustrated in FIG. The brightness correction coefficient calculation unit 23 sets the first brightness correction coefficient 41 to 1.0. Accordingly, when the average pixel value AveRGB is equal to or smaller than the threshold Tp, the plurality of LED display elements 61 when the video signal processed by the video signal processing unit 14 is corrected by the first brightness correction coefficient 41. The brightness does not change from the brightness of the plurality of LED display elements 61 when the video signal is not corrected by the first brightness correction coefficient 41.

On the other hand, when the average pixel value AveRGB is larger than the threshold value Tp for calculating the brightness correction coefficient, the brightness correction control unit 21 sets the first brightness correction coefficient smaller than 1.0 as illustrated in FIG. The brightness correction coefficient calculator 23 calculates the first brightness correction coefficient 41 so that the first brightness correction coefficient 41 has a value smaller than 1.0. Thus, when the average pixel value AveRGB is larger than the threshold value Tp, the brightness of the plurality of LED display elements 61 when the video signal processed by the video signal processing unit 14 is corrected by the first brightness correction coefficient 41. However, the luminance is lower than the luminance of the plurality of LED display elements 61 when the video signal is not corrected by the first luminance correction coefficient 41. Thereby, when the brightness of the plurality of LED display elements 61 is high and the power consumption PWa of the LED display device 1 is large, the power consumption of the LED display device 1 can be suppressed.

When the average pixel value AveRGB is larger than the threshold value Tp for calculating the brightness correction coefficient, the brightness correction coefficient calculation unit 23 causes the first brightness to increase as the average pixel value AveRGB increases, as shown in FIG. The first brightness correction coefficient 41 is calculated so that the correction coefficient 41 becomes small. Therefore, the calculated first brightness correction coefficient 41 becomes smaller as the average pixel value AveRGB approaches the maximum pixel value 255 from the threshold Tp.

Further, when the average pixel value AveRGB is larger than the threshold value Tp for calculating the brightness correction coefficient, the brightness correction coefficient calculation unit 23 is corrected by the first brightness correction coefficient 41 as illustrated in FIG. The first brightness correction coefficient 41 is calculated so that the average pixel value indicating the average of the plurality of pixel values included in the video signal becomes the threshold Tp. In the calculation of the first brightness correction coefficient 41 as described above, the brightness correction coefficient calculation unit 23 reads out the calculation formulas, tables and the like stored in the memory 52 and the like, and calculates using the read calculation formulas, tables and the like. It can be executed by executing it.

For example, the first brightness correction coefficient Mula (first brightness correction coefficient 41) can be calculated by (Equation 4).

In step S10, the brightness correction control unit 21 reads from the brightness information storage unit 17 m average pixel values AveRGB each indicating the brightness of the latest m continuous frames.

In subsequent step S11, the brightness correction control unit 21 determines whether or not all of the m average pixel values AveRGB read from the brightness information storage unit 17 are equal to or more than the threshold value Tc for selecting the drive current value. .. When it is determined that at least a part of the m average pixel values AveRGB is smaller than the threshold value Tc, steps S12 and S13 are executed and then step S17 is executed. When it is determined that all of the m average pixel values AveRGB are equal to or more than the threshold value Tc, steps S14, S15 and S16 are executed and then step S17 is executed.

In step S12, the brightness correction control unit 21 selects the first drive current values IRa, IGa, and IBa (first drive current value 31) as drive current values, and the first brightness correction coefficient 41 is used for brightness correction. Select as a coefficient.

In the following step S13, the correction processing unit 18 corrects the video signal processed by the video signal processing unit 14 by the first brightness correction coefficient 41 calculated by the brightness correction coefficient calculation unit 23. At that time, the correction processing unit 18 multiplies the pixel value indicating the brightness of the plurality of LED display elements 61 by the first brightness correction coefficient 41.

In step S14, the brightness correction control unit 21 selects the second drive current values IRb, IGb, and IBb (second drive current value 32) as the drive current value, and the second brightness correction coefficient 42 is used for brightness correction. Select as a coefficient.

In the subsequent step S15, the brightness correction coefficient calculation unit 23 calculates the second brightness correction coefficient based on the read average pixel value AveRGB so that the second brightness correction coefficient 42 becomes a value smaller than 1.0. Calculate

In the subsequent step S16, the correction processing unit 18 corrects the video signal processed by the video signal processing unit 14 by the second brightness correction coefficient 42 calculated by the brightness correction coefficient calculation unit 23. At that time, the correction processing unit 18 multiplies the pixel value indicating the brightness of the plurality of LED display elements 61 by the second brightness correction coefficient 42.

In step S17, the drive current value calculator 22 calculates the drive current value to be passed to the driver 19. If the first drive current values IRa, IGa and IBa (first drive current value 31) are selected in step S12, the calculated drive current values are the first drive current values IRa, IGa and IBa ( If the first drive current value 31) and the second drive current values IRb, IGb and IBb (second drive current value 32) are selected in step S14, the second drive current values IRb, IGb are selected. And IBb (second drive current value 32). Further, the drive unit 19 drives the plurality of LED display elements 61 with the drive current value calculated by the drive current value calculation unit 22 according to the video signal corrected by the correction processing unit 18.

FIG. 9 is a graph showing the relationship between the average pixel value AveRGB calculated by the LED display device of the first embodiment and the second brightness correction coefficient calculated by the LED display device. The horizontal axis of the graph shown in FIG. 9 indicates the average pixel value AveRGB. The second luminance correction coefficient 42 is plotted on the vertical axis of the graph shown in FIG.

When the average pixel value AveRGB is smaller than the threshold value Tc for selecting the drive current value, the brightness correction coefficient calculation unit 23 sets the second brightness correction coefficient 42 to 1.0 as illustrated in FIG. ..

On the other hand, when the average pixel value AveRGB is greater than or equal to the threshold value Tc for selecting the drive current value, the brightness correction coefficient calculation unit 23 determines that the second brightness correction coefficient 42 is 1. The second brightness correction coefficient 42 is calculated so as to have a value smaller than 0. Thus, the brightness of the plurality of LED display elements 61 when the video signal processed by the video signal processing unit 14 is corrected by the second brightness correction coefficient 42 is the second brightness correction coefficient of the video signal. The brightness is lower than the brightness of the plurality of LED display elements 61 when not corrected by 42. Accordingly, when the brightness of the plurality of LED display elements 61 is high and the power consumption of the LED display device 1 is large, the power consumption of the LED display device 1 can be suppressed.

Further, when the average pixel value AveRGB is equal to or larger than the threshold value Tc for selecting the drive current value, as shown in FIG. 9, the brightness correction coefficient calculation unit 23 causes the second pixel as the average pixel value AveRGB increases. The second brightness correction coefficient 42 is calculated so that the brightness correction coefficient 42 becomes smaller. Therefore, the calculated second brightness correction coefficient 42 becomes smaller as the average pixel value AveRGB approaches the maximum pixel value 255 from the threshold value Tc.

Further, when the average pixel value AveRGB is equal to or larger than the threshold value Tc for selecting the drive current value, the brightness correction coefficient calculation unit 23 is corrected by the second brightness correction coefficient 42 as illustrated in FIG. The second luminance correction coefficient 42 is calculated so that the average pixel value indicating the average of the plurality of pixel values included in the video signal becomes the threshold value Tc. The calculation of the second brightness correction coefficient 42 as described above is performed by the brightness correction coefficient calculation unit 23 by reading the calculation formulas, tables and the like stored in the memory 52 and the like and using the read calculation formulas, tables and the like. It can be executed by executing it.

For example, the second luminance correction coefficient Mulb (second luminance correction coefficient 42) can be calculated by (Equation 5).

Here, the drive current value is selected from the first drive current values IRa, IGa and IBa (first drive current value 31) and the second drive current values IRb, IGb and IBb (second drive current value 32). A method of calculating the threshold value Tc for doing so will be described.

When the threshold value Tc for selecting the drive current value is calculated, first, the first drive current values IRa, IGa and IBa (first drive current value 31) and the maximum value are displayed in the plurality of LED display elements 61. A PWM signal having a duty ratio according to the pixel value 255 is supplied to all the plurality of LED display elements 61 to be turned on, and the luminances YRa, YGa and YBa of the plurality of LED display elements 61 are measured by a measuring device (not shown). .. Further, the plurality of LED display elements 61 are supplied with the second drive current values IRb, IGb and IBb (the second drive current value 32), and the PWM signal having the duty ratio according to the maximum pixel value 255 is supplied to the plurality of LED display elements 61. The LED display elements 61 are all turned on, and the luminances YRb, YGb and YBb of the plurality of LED display elements 61 are measured by a measuring device (not shown).

Luminance YRTa, YGTa and YBTa of the plurality of LED display elements 61 when the average pixel value AveRGB is the threshold Tp for calculating the luminance correction coefficient, using the measured luminance YRa, YGa and YBa, and the threshold Tp. , (Equation 6).

The threshold value Tc for selecting the drive current value is set so as to satisfy (Equation 7).

When the threshold value Tc for selecting the drive current value is set so as to satisfy (Equation 7), the video signal processed by the video signal processing unit 14 is corrected by the first luminance correction coefficient 41. Luminance YRa, YGa and YBa of the plurality of LED display elements 61 when the plurality of LED display elements 61 are driven with the drive current values IRa, IGa and IBa of 1 (first drive current value 31), and the video signal. Are corrected by the second brightness correction coefficient 42 and the plurality of LED display elements 61 are driven by the second drive current values IRb, IGb and IBb (second drive current value 32). And the luminances YRb, YGb, and YBb of are in agreement when the average pixel value AveRGB is the threshold value Tc. That is, the luminances YRa, YGa and YBa and the luminances YRb, YGb and YBb satisfy the relationship of (YRa, YGa and YBa)=(YRb, YGb and YBb) when the average pixel value AveRGB is the threshold value Tc. Therefore, the drive current values are the first drive current values IRa, IGa and IBa (first drive current value 31) and the second drive current values IRb, IGb and IBb (second drive current value 32). It is possible to prevent the brightness of the plurality of LED display elements 61 from changing discontinuously when they are switched between.

The first drive current values IRa, IGa and IBa and the second drive current values IRb, IGb and IBb satisfy the relationship of (IRb, IGb, IBb) <(IRa, IGa, IBa). Therefore, the luminances YRa, YGa and YBa, and the luminances YRb, YGb and YBb satisfy the relationship of (YRb, YGb, YBb)<(YRa, YGa, YBa). Therefore, the threshold values Tp and Tc satisfy the relationship of Tp<Tc.

When the PWM signals having the duty ratios corresponding to the second drive current values IRb, IGb and IBb and the maximum pixel value 255 are supplied to the plurality of LED display elements 61 and the plurality of LED display elements 61 are all turned on. When the power consumption of the LED display device 1 is PWball, an average pixel which matches the second drive current values IRb, IGb and IBb for the plurality of LED display elements 61 and the threshold value Tc for selecting the drive current value. The power consumption PWb of the LED display device 1 when the PWM signal having the duty ratio corresponding to the value AveRGB is supplied and the plurality of LED display elements 61 are all turned on is represented by (Equation 8).

Further, as described above, the luminous efficiency of the LED decreases as the driving current approaches the maximum. Therefore, the power consumptions PWb and PWt satisfy the relationship of PWb<PWt.

1.7 Effect of the Invention of Embodiment 1 According to the invention of Embodiment 1, the drive current value is determined so that the power consumption of the LED display device 1 is equal to or less than the set upper limit value PWt, and the brightness correction coefficient is Is calculated. Thereby, the power consumption of the LED display device 1 can be set to the set upper limit value PWt or less.

Further, according to the invention of the first embodiment, the luminance information is calculated from the video signal processed by the video signal processing unit 14. Further, the drive current value is determined based on the calculated brightness information. Further, the brightness correction coefficient is calculated based on the determined drive current value. As a result, while driving the plurality of LED display elements 61 with a drive current value at which the luminous efficiency of the plurality of LED display elements 61 becomes high, deterioration of the image quality of the LED display device 1 related to the brightness of the plurality of LED display elements 61 is prevented. Can be suppressed.

Further, according to the invention of the first embodiment, the luminance information indicating the luminance of each frame is calculated from the video signal processed by the video signal processing unit 14. In addition, the drive current value is determined based on a plurality of pieces of brightness information indicating the calculated brightness of each of the plurality of frames. Thereby, the image quality of the LED display device 1 related to the brightness of the plurality of LED display elements 61 can be stabilized.

With these, it is possible to suppress the deterioration of the image quality of the LED display device 1 while suppressing the power consumption of the LED display device 1. Further, at that time, the image quality of the LED display device 1 can be stabilized.

Furthermore, according to the invention of the first embodiment, when the average pixel value AveRGB is equal to or less than the threshold value Tp for calculating the brightness correction coefficient, the power consumption of the LED display device 1 is equal to or less than the power saving control target value PWt. Is set to the threshold value Tp. When the average pixel value AveRGB is larger than the threshold Tp, the video signal is corrected by the first brightness correction coefficient or the second brightness correction coefficient to which a value smaller than 1 is assigned, and the brightness of the plurality of LED display elements 61 is corrected. Is lowered. Therefore, the power consumption of the LED display device 1 can be set to the power saving control target value PWt or less.

Furthermore, according to the invention of the first embodiment, the threshold value Tc for selecting the drive current value from the first drive current value 31 and the second drive current value 32 smaller than the first drive current value 31 is: A plurality of LED displays when the video signal is corrected by the first brightness correction coefficient 41 calculated based on the first drive current value 31 and the plurality of LED display elements 61 are driven by the first drive current value 31. The video signal is corrected by the brightness of the element 61 and the second brightness correction coefficient 42 calculated based on the second drive current value 32, and the plurality of LED display elements 61 are driven by the second drive current value 32. When the average pixel value AveRGB is the threshold value Tc, the luminances of the plurality of LED display elements 61 are set to match. Thereby, when the drive current value is switched between the first drive current value 31 and the second drive current value 32, it is possible to prevent the brightness of the plurality of LED display elements 61 from changing discontinuously. Therefore, the image quality of the LED display device 1 related to the brightness of the plurality of LED display elements 61 can be further stabilized.

Further, according to the invention of the first embodiment, when the average pixel value AveRGB is equal to or larger than the threshold value Tc for selecting the drive current value, the drive current value is the first drive current which is the initial drive current value. The value is switched to the second drive current value which is an additional drive current value smaller than the initial drive current value. As a result, the drive current value can be suppressed from approaching the maximum drive current value at which the light emission efficiency of the LED decreases, and the power consumption of the LED display device 1 can be suppressed.

Furthermore, according to the invention of the first embodiment, when the average pixel value AveRGB becomes equal to or larger than the threshold value Tc for selecting the drive current value, the drive current value is smaller than the first drive current value. And the luminance correction coefficient is changed from the first luminance correction coefficient to the larger second luminance correction coefficient. As a result, it is possible to suppress the dynamic range of the image displayed on the display unit 11 from being reduced while suppressing the power consumption of the LED display device 1. For example, the drive current value is changed, the brightness correction coefficient is changed, the threshold value Tp for calculating the brightness correction coefficient is 128, the threshold value Tc is 190, and it is included in the m average pixel values. If one average pixel value AveRGB is 200, it is assumed that the maximum pixel value 255 included in the video signal is converted into the pixel value 242 included in the video signal corrected by the correction processing unit 18. In this case, the video signal not corrected by the correction processing unit 18 has 255 gradations, and the video signal corrected by the correction processing unit 18 has 243 gradations. However, when the drive current value is not changed and only the brightness correction coefficient is changed, the video signal corrected by the correction processing unit 18 has only 164 gradations. Therefore, when the drive current value is not changed and only the brightness correction coefficient is changed, the display unit 11 is compared with the case where the drive current value is changed and the brightness correction coefficient is changed. The dynamic range of the displayed image is reduced, and visual problems such as collapse of output gradation occur. Therefore, by changing the drive current value and the luminance correction coefficient, power saving control can be performed without reducing the dynamic range of the image displayed on the display unit 11, and the display on the display unit 11 can be performed. It is possible to suppress the power consumption of the LED display device 1 while suppressing the deterioration of the image quality of the displayed image.

Furthermore, according to the invention of the first embodiment, when the drive current value is once changed, the drive current is maintained until the end of m consecutive frames, so that the image displayed on the display unit 11 is a moving image. Even when it is, it is possible to prevent the viewer of the video from being given a sense of discontinuity due to the change in the dynamic range due to the change in the drive current value, and to save power while stabilizing the video displayed on the display unit 11. Control can be performed. Generally speaking, since the video signals have a correlation in the time direction, even if the drive current value is maintained in such a manner, it is unlikely that the display of the video on the display unit 11 will be hindered.

1.8 Modified Example In the first embodiment, the threshold value for selecting the drive current value is one kind of threshold value Tc. In addition, at least a part of the m average brightness values AveRGB each indicating the brightness of m consecutive frames is smaller than the threshold value Tc, and then all the m average brightness values AveRGB are changed to the threshold value Tc or more. In this case, the drive current value is switched from the first drive current value 31 to the second drive current value 32. In addition, when all of the m average luminance values AveRGB are equal to or more than the threshold value Tc and at least a part of the m average luminance values AveRGB is changed to a state of being smaller than the threshold value Tc, the drive current value is the second drive value. The current value 32 is switched to the first drive current value 31.

However, the threshold value for selecting the drive current value may be two or more kinds of threshold values. For example, the threshold value for selecting the drive current value may be two kinds of threshold values Tc1 and Tc2. When the thresholds for selecting the drive current value are the two types of thresholds Tc1 and Tc2, for example, from the state in which at least a part of the m average brightness values AveRGB is smaller than the threshold Tc1, When all are changed to the state of being equal to or more than the threshold value Tc1, the drive current value is switched from the first drive current value 31 to the second drive current value 32. In addition, when all of the m average brightness values AveRGB are equal to or more than the threshold value Tc2 and at least a part of the m average brightness values AveRGB is changed to a value smaller than the threshold value Tc2, the drive current value is the second drive value. The current value 32 is switched to the first drive current value 31.

Further, in the first embodiment, the brightness correction control unit 21 determines that at least a part of the m average brightness values AveRGB indicating the brightness of each of m continuous frames is greater than the threshold value Tc for selecting the drive current value. If it is smaller, the first drive current value 31 is selected as the drive current value. In addition, the brightness correction control unit 21 selects the second drive current value 32 as the drive current value when all of the m average brightness values AveRGB are equal to or greater than the threshold value Tc.

However, when the average of the m average brightness values AveRGB indicating the brightness of each of the m continuous frames is smaller than the threshold value Tc for selecting the drive current value, the brightness correction control unit 21 determines the first drive current. The value 31 may be selected as the drive current value, and the second drive current value 32 may be selected as the drive current value when the average of the m average luminance values AveRGB is equal to or greater than the threshold value Tc.

FIG. 10 is a timing chart for explaining the timing at which the LED display device according to the first embodiment and the modification thereof determines and calculates the drive current value and the brightness correction coefficient. FIG. 10A illustrates the timing at which the LED display device 1 according to the first embodiment determines and calculates the drive current value and the brightness correction coefficient. FIG. 10B illustrates the timing at which the LED display device of the modified example of the first embodiment determines and calculates the drive current value and the brightness correction coefficient.

In the LED display device 1 according to the first embodiment, the calculation unit 16 determines the drive current value and the brightness correction coefficient for each frame, and calculates the drive current value and the brightness correction coefficient. For example, the calculation unit 16 determines the drive current value and the brightness correction coefficient for each frame f1,..., F22 illustrated in FIG. 10A, and calculates the drive current value and the brightness correction coefficient. .. At that time, the calculation unit 16 uses m average brightness values AveRGB indicating the brightness of m consecutive frames before each frame. For example, when the calculation unit 16 determines the drive current value and the brightness correction coefficient for the frames f7, f8, and f9 and calculates the drive current value and the brightness correction coefficient, the brightness of the m frames f7a, f8a, and f9a is calculated. The m average brightness values AveRGB shown are used.

However, the calculation unit 16 may determine the drive current value and the brightness correction coefficient for each of the frames that match the number of m frames, and calculate the drive current value and the brightness correction coefficient. For example, the calculation unit 16 may determine the drive current value and the brightness correction coefficient for each frame of f7, f14, and f21 illustrated in FIG. 10B, and calculate the drive current value and the brightness correction coefficient. .. At that time, the calculation unit 16 uses m average brightness values AveRGB indicating the brightness of m consecutive frames before each frame. For example, when the calculation unit 16 determines the drive current values for the frames f7, f14, and f21 and calculates the brightness correction coefficient, the calculation unit 16 calculates m average brightness values AveRGB indicating the brightness of the m frames f7a, f14a, and f21a, respectively. To use.

It should be noted that the present invention can appropriately modify or omit the embodiments within the scope of the invention.

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

1 LED display device, 11 display unit, 13 power saving control target value input unit, 15 brightness information calculation unit, 16 calculation unit, 17 brightness information storage unit, 18 correction processing unit, 19 drive unit, 31 first drive current value , 32 second drive current value, 41 first brightness correction coefficient, 42 second brightness correction coefficient, 61 multiple LED display elements.

Claims (9)

A brightness information calculation unit that calculates brightness information indicating the brightness of each frame from the video signal;
A drive current value is determined based on a plurality of pieces of brightness information respectively indicating the brightness of a plurality of frames so that the power consumption of the LED display device is equal to or less than a set upper limit value, and based on the brightness information and the drive current value. And a calculation unit for calculating the brightness correction coefficient,
A display unit including a plurality of LED display elements;
A correction processing unit that corrects the video signal by the brightness correction coefficient to obtain a corrected video signal,
A drive unit that drives the plurality of LED display elements with the drive current value according to the corrected video signal;
LED display device. Further comprising an input unit for inputting the upper limit value,
The arithmetic unit is
Setting a threshold value for calculating the brightness correction coefficient based on the upper limit value,
When the brightness information is larger than a threshold value for calculating the brightness correction coefficient, the brightness of the plurality of LED display elements when the video signal is corrected by the brightness correction coefficient is when the video signal is not corrected. The LED display device according to claim 1, wherein the brightness correction coefficient is calculated so as to be lower than the brightness of the plurality of LED display elements. The arithmetic unit is
Determining the drive current value by selecting the drive current value from a first drive current value and a second drive current value smaller than the first drive current value,
When at least a part of the plurality of brightness information is smaller than a threshold value for selecting the drive current value, the first drive current value is selected as the drive current value, and all of the plurality of brightness information are the 3. The LED display device according to claim 1, wherein the second drive current value is selected as the drive current value when the drive current value is equal to or more than a threshold value for selecting the drive current value. The arithmetic unit is
Determining the drive current value by selecting the drive current value from a first drive current value and a second drive current value smaller than the first drive current value,
If the average of the plurality of brightness information is smaller than the threshold for selecting the drive current value, the first drive current value is selected as the drive current value, and the average of the plurality of brightness information is the drive current. The LED display device according to claim 1, wherein the second drive current value is selected as the drive current value when the value is equal to or larger than a threshold value for selecting a value. The threshold value for selecting the drive current value is such that the video signal is corrected by the first luminance correction coefficient calculated based on the first drive current value, and the plurality of LEDs are operated at the first drive current value. The video signal is corrected by the brightness of the plurality of LED display elements when the display element is driven and the second brightness correction coefficient calculated based on the second drive current value, and the second drive current is corrected. The brightness of the plurality of LED display elements when the plurality of LED display elements are driven by a value is set to match when the brightness information is a threshold value for selecting the drive current value. 5. The LED display device according to claim 3 or 4. The LED display device according to claim 1, wherein the plurality of frames are two or more consecutive frames. 7. The LED display device according to claim 1, wherein the calculation unit determines the drive current value for each frame and calculates the brightness correction coefficient. 7. The LED display device according to claim 1, wherein the arithmetic unit determines the drive current value and arithmetically operates the luminance correction coefficient for each of a number of frames corresponding to the number of the plurality of frames. a) calculating luminance information indicating the luminance of each frame from the video signal,
b) The drive current value is determined based on a plurality of brightness information indicating the brightness of each of a plurality of frames so that the power consumption of the LED display device is equal to or less than the set upper limit value, and the brightness information and the drive current value are determined. Calculating a brightness correction coefficient based on
c) a step of correcting the video signal with the luminance correction coefficient to obtain a corrected video signal,
d) driving a plurality of LED display elements provided in the LED display device with the drive current value according to the corrected video signal,
A method for correcting the brightness of an LED display device comprising:

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