WO2021038794A1 - Led display device - Google Patents

Led display device Download PDF

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Publication number
WO2021038794A1
WO2021038794A1 PCT/JP2019/033911 JP2019033911W WO2021038794A1 WO 2021038794 A1 WO2021038794 A1 WO 2021038794A1 JP 2019033911 W JP2019033911 W JP 2019033911W WO 2021038794 A1 WO2021038794 A1 WO 2021038794A1
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WIPO (PCT)
Prior art keywords
drive current
correction coefficient
luminance
current value
video signal
Prior art date
Application number
PCT/JP2019/033911
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French (fr)
Japanese (ja)
Inventor
隆志 的場
浅村　吉範
Original Assignee
三菱電機株式会社
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Priority to PCT/JP2019/033911 priority Critical patent/WO2021038794A1/en
Publication of WO2021038794A1 publication Critical patent/WO2021038794A1/en

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    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/22—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources
    • G09G3/30—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels
    • G09G3/32—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED]

Definitions

  • the present invention relates to an LED display device.
  • a light emitting diode (LED: Light Emitting Diode) display device includes a display unit including a plurality of LEDs. With the technological development and cost reduction of LEDs, LED display devices have come to be widely used for displaying advertisements indoors and outdoors.
  • 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 to display a conference image, a surveillance image, etc. indoors. Is becoming.
  • the panel current flowing through all the pixels is predicted when the display panel is displayed based on the image data (paragraph 0012). Further, when the predicted panel current exceeds the set value, the set contrast or brightness is corrected (paragraph 0015). Also, 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).
  • 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.
  • the present invention relates to an LED display device.
  • the LED display device includes a luminance information calculation unit, a drive current value selection unit, a luminance correction coefficient calculation unit, a correction calculation unit, a display unit, and a drive circuit.
  • the luminance information calculation unit calculates the luminance information from the video signal.
  • the drive current value selection unit selects a drive current value from n types of drive current values based on the brightness information.
  • n is an integer of 2 or more.
  • the brightness correction coefficient calculation unit calculates n types of brightness correction coefficients corresponding to each of n types of drive current values based on the brightness information.
  • the correction calculation unit corrects the video signal with the brightness correction coefficient corresponding to the drive current value and obtains the corrected video signal.
  • the display unit is equipped with a plurality of LEDs.
  • the drive circuit drives a plurality of LEDs with a selected drive current value according to the corrected video signal.
  • a plurality of LEDs are driven by a drive current value selected based on the luminance information. Therefore, it is possible to drive the plurality of LEDs with a drive current value that increases the luminous efficiency of the plurality of LEDs.
  • the video signal is corrected by the luminance correction coefficient according to the selected drive current value. Therefore, it is possible to suppress deterioration of the image quality of the LED display device related to the brightness of the plurality of LEDs while driving the plurality of LEDs with a drive current value that increases the luminous efficiency of the plurality of LEDs.
  • FIG. 1 It is a block diagram which illustrates the light emitting diode (LED: Light Emitting Diode) display device of Embodiment 1.
  • FIG. It is a top view which shows another example of the image display area of the LED display device of Embodiment 1.
  • FIG. It is a figure explaining the signal and information handled by the LED display device of Embodiment 1.
  • FIG. It is a timing chart explaining the PWM drive performed by the LED display device of Embodiment 1.
  • It is a graph which illustrates the example of the current luminance characteristic which shows the relationship between the current value of the current flowing through LED, and the luminance of LED.
  • It is a flowchart which illustrates the flow of the power saving control executed by the LED display device of Embodiment 1.
  • FIG. 1 It is a block diagram which illustrates the light emitting diode (LED: Light Emitting Diode) display device of Embodiment 1.
  • FIG. It is a top view which shows another example of the image display area of the LED
  • FIG. 6 is a graph illustrating the relationship between the average pixel value AveRGB calculated by the LED display device of the first embodiment and the first luminance correction coefficient calculated by the LED display device. It is a graph which shows the relationship between the average pixel value AveRGB calculated by the LED display device of Embodiment 1 and the second luminance correction coefficient calculated by the LED display device.
  • FIG. 1 is a block diagram illustrating a light emitting diode (LED) display device according to the first embodiment.
  • the LED display device 1 of the first embodiment illustrated in FIG. 1 displays an image corresponding 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 is equal to or less than the power saving control target value input from the outside.
  • the LED display device 1 includes an input terminal 11, a video signal processing circuit 12, a power saving control target value input unit 13, a luminance correction control circuit 14, a drive circuit 15, and a display unit 16.
  • the display unit 16 includes a plurality of pixels 21.
  • each pixel 21i included in the plurality of pixels 21 is composed of an LED display element.
  • the LED display element includes a plurality of LEDs having a plurality of emission colors different from each other. Therefore, the display unit 16 includes a plurality of LEDs.
  • the plurality of emission colors different from each other are red (R), green (G), and blue (B).
  • a video signal is input to the input terminal 11.
  • the video signal processing circuit 12 processes the input video signal to obtain the processed video signal.
  • the processing to be performed is gamma correction or the like.
  • the power saving control target value is input to the power saving control target value input unit 13.
  • the input power saving control target value indicates the upper limit of the power consumption of the LED display device 1.
  • the brightness correction control circuit 14 corrects the processed video signal and obtains the corrected video signal. Further, the luminance correction control circuit 14 determines the drive current values of a plurality of LEDs provided in the display unit 16 based on the processed video signal. Further, the brightness correction control circuit 14 corrects the processed video signal so that the power consumption of the LED display device 1 is equal to or less than the input power saving control target value, and determines the drive current values of the plurality of LEDs. ..
  • the drive circuit 15 drives a plurality of LEDs provided in the display unit 16 with a determined drive current value according to the corrected video signal.
  • the plurality of LEDs provided in the display unit 16 emit light with a brightness corresponding to the corrected video signal and the determined drive current value. As a result, the display unit 16 displays the corrected video signal and the video corresponding to the determined drive current value.
  • the luminance correction control circuit 14 and the drive circuit 15 correct the luminance and / or dynamic range of each frame image constituting the image represented by the corrected image signal. Further, the display unit 16 displays an image by sequentially displaying each frame image whose brightness and / or dynamic range has been corrected.
  • the display unit 16 includes a plurality of pixels 21 as shown in FIG. FIG. 1 shows a case where the plurality of pixels 21 are 16 pixels of 4 pixels in the horizontal direction and 4 pixels in the vertical direction.
  • the display unit 16 has a video display area 22.
  • the plurality of pixels 21 are arranged in the video display area 22.
  • the plurality of pixels 21 are arranged in a matrix.
  • FIG. 2 is a plan view illustrating another example of the image display area of the LED display device of the first embodiment.
  • the image display area 23 illustrated in FIG. 2 is an image display area when the display unit 16 has an input resolution of 1920 pixels in the horizontal direction and 1080 pixels in the vertical direction. Therefore, in the image display area 23 shown in FIG. 2, 1980 ⁇ 1080 pixels of 1920 pixels in the horizontal direction ⁇ 1080 pixels in the vertical direction are arranged.
  • FIG. 3 is a diagram illustrating signals and information handled by the LED display device of the first embodiment.
  • the LED display device 1 includes a luminance information calculation circuit 31, a drive current value selection circuit 32, a luminance correction coefficient calculation circuit 33, and a correction calculation circuit 34.
  • the brightness information calculation circuit 31, the drive current value selection circuit 32, the brightness correction coefficient calculation circuit 33, and the correction calculation circuit 34 are provided in the brightness correction control circuit 14.
  • the brightness correction control circuit 14, the brightness information calculation circuit 31, the drive current value selection circuit 32, the brightness correction coefficient calculation circuit 33, and the correction calculation circuit 34 are the brightness correction control unit, the brightness information calculation unit, the drive current value selection unit, and the brightness, respectively.
  • This is a circuit that constitutes a correction coefficient calculation unit and a correction calculation unit. All or part of the luminance correction control unit, the luminance information calculation unit, the drive current value selection unit, the luminance correction coefficient calculation unit, and the correction calculation unit may be configured by a computer that executes the program.
  • the luminance information calculation circuit 31 calculates the luminance information 42 shown in FIG. 3 from the video signal 41 shown in FIG.
  • the video signal 41 is a video signal processed by the video signal processing circuit 12, and is input from the video signal processing circuit 12.
  • the calculated luminance information 42 indicates the luminance of a plurality of LEDs provided in the display unit 16.
  • the video signal 41 includes a plurality of pixel values indicating the brightness of each of the plurality of pixels 21.
  • the brightness value indicating the brightness of each pixel 21i includes the pixel value indicating the brightness of the R LED, the G LED, and the B LED provided in each pixel 21i. Therefore, the video signal 41 includes a plurality of pixel values 43 indicating the brightness of each of the plurality of LEDs provided in the display unit 16.
  • the plurality of pixel values 43 are included in the luminance signal included in the video signal 41.
  • the luminance information 42 includes the sum or average 44 of the plurality of pixel values 43.
  • the drive current value selection circuit 32 selects the drive current value 45s shown in FIG. 3 from the n types of drive current values 45 shown in FIG. 3 based on the calculated luminance information 42.
  • n is an integer of 2 or more.
  • the n types of drive current values 45 include an initial drive current value 45a and at least one additional drive current value 45b smaller than the initial drive current value 45a.
  • the drive current value selection circuit 32 selects the drive current value 45s based on the magnitude relationship between the calculated luminance information 42 and the threshold value 46 for selecting the drive current value 45s shown in FIG. In the first embodiment, the drive current value selection circuit 32 selects the drive current value 45s based on the magnitude relationship between the calculated sum or average 44 and the threshold value 46 for selecting the drive current value 45s.
  • the brightness correction coefficient calculation circuit 33 calculates n types of brightness correction coefficients 47 shown in FIG. 3 based on the calculated brightness information 42.
  • the luminance correction coefficient calculation circuit 33 calculates n kinds of luminance correction coefficients 47 based on the calculated total or average 44.
  • the n types of brightness correction coefficients 47 correspond to n types of drive current values 45, respectively.
  • the luminance correction coefficient calculation circuit 33 sets a threshold value 49 for calculating the n types of luminance correction coefficients 47 shown in FIG. 3 based on the power saving control target value 48 shown in FIG. Further, in the luminance correction coefficient calculation circuit 33, when the calculated luminance information 42 is larger than the threshold value 49 for the calculation of the n types of luminance correction coefficients 47, the video signal 41 is based on each of the n types of luminance correction coefficients 47.
  • the n kinds of luminance correction coefficients 47 are calculated so that the luminance of the plurality of LEDs provided in the display unit 16 when corrected is smaller than that when the video signal 41 is not corrected.
  • the correction calculation circuit 34 corrects the video signal 41 with the luminance correction coefficient 47s corresponding to the selected drive current value 45s, and obtains the corrected video signal 50 shown in FIG.
  • the correction calculation circuit 34 corrects the video signal 41 by multiplying the plurality of pixel values 43 by the luminance correction coefficient 47s. Therefore, the corrected video signal 50 includes the plurality of pixel values 51 shown in FIG. 3 obtained by multiplying the plurality of pixel values 43 by the luminance correction coefficient 47s.
  • the drive circuit 15 drives a plurality of LEDs provided in the display unit 16 with a selected drive current value of 45 s according to the corrected video signal 50.
  • the drive circuit 15 PWM-drives a plurality of LEDs provided in the display unit 16 by a pulse width modulation (PWM) method.
  • PWM pulse width modulation
  • the drive circuit 15 drives the plurality of LEDs at the drive current value of 45 s by supplying the drive signal 52 shown in FIG. 3 having the selected drive current value of 45 s to the plurality of LEDs. Therefore, by changing the drive current value 45s, it is possible to adjust the brightness of the plurality of LEDs during the on period and the average brightness during one frame period.
  • the drive circuit 15 has a duty ratio 53 corresponding to the corrected video signal 50, and by supplying the drive signal 52 shown in FIG. 3 to the plurality of LEDs, the corrected video signal 50 is obtained. Therefore, the plurality of LEDs are driven. Therefore, by changing the brightness correction coefficient 47s, the average brightness of the plurality of LEDs in one frame period can be adjusted.
  • the n types of drive current values 45 are two types of drive current values including a first drive current value and a second drive current value.
  • the first drive current value is the initial drive current value 45a.
  • the second drive current value is an additional drive current value 45b smaller than the initial drive current value 45a.
  • the n types of brightness correction coefficients 47 are two types of brightness correction coefficients including a first brightness correction coefficient and a second brightness correction coefficient.
  • the first luminance correction coefficient and the second luminance correction coefficient correspond to the first drive current value and the second drive current value, respectively.
  • the luminance correction coefficient calculation circuit 33 includes a first luminance correction coefficient calculation circuit 33a and a second luminance correction coefficient calculation circuit 33b that calculate the first luminance correction coefficient and the second luminance correction coefficient, respectively.
  • FIG. 4 is a timing chart illustrating the PWM drive performed by the LED display device of the first embodiment.
  • FIG. 4A illustrates the waveform of a signal including a pulse emitted each time the basic period of PWM drive elapses.
  • 4 (b) and 4 (c) show the current waveform of the drive signal supplied to the LED.
  • the basic period of PWM drive shown in FIG. 4A is one frame period of the corrected video signal 50.
  • the drive signal illustrated in FIGS. 4 (b) and 4 (c) gives the drive signal a pulse height corresponding to the selected drive current value 45s and a duty ratio corresponding to the pixel value indicating the brightness of the LED. It has a current pulse with a pulse width.
  • a drive current having a drive current value of 45 s flows through the LED during the on-period having the pulse width.
  • the pulse width is one frame period or less.
  • the current pulse illustrated in FIG. 4B has a pulse width PWM1 that gives the drive signal a duty ratio of 100%.
  • the current pulse illustrated in FIG. 4C has a pulse width PWM2 that gives the drive signal a duty ratio of 75%.
  • the energizing time of the LED in one frame period becomes shorter as the duty ratio of the drive signal supplied to the LED becomes smaller. Therefore, the average brightness of the LED in one frame period becomes lower as the duty ratio of the drive signal supplied to the LED becomes smaller.
  • the energizing time of the LED in one frame period is the duty ratio of 100% shown in FIG. 4 (b). It is shorter than that when the drive signal having is supplied to the LED.
  • the average brightness of the LED in one frame period is the duty ratio of 100% shown in FIG. 4B.
  • the drive signal with is higher than that when supplied to the LED. Therefore, the average brightness of the LED in one frame period can be adjusted by changing the duty ratio of the drive signal supplied to the LED. Further, as the duty ratio of the drive signal supplied to the LED becomes smaller, the energization time of the LED in one frame period becomes shorter, so that the power consumption of the LED in one frame period is the duty ratio of the drive signal supplied to the LED. The smaller it is, the smaller it becomes. For example, when a drive signal having a duty ratio of 75% shown in FIG. 4 (c) is supplied to the LED, the power consumption of the LED in one frame period is 100% duty ratio shown in FIG. 4 (b). The drive signal with is smaller than that when supplied to the LED.
  • the average brightness of the LED in one frame period becomes lower as the duty ratio of the drive 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 drive signal supplied to the LED becomes smaller. Therefore, as the brightness of the LED indicated by the pixel value included in the video signal 41 becomes lower, the duty ratio of the drive signal supplied to the LED becomes smaller, and the power consumption of the LED in one frame period becomes smaller. On the other hand, as the brightness of the LED indicated by the pixel value included in the video signal 41 increases, the duty ratio of the drive signal supplied to the LED increases, and the power consumption of the LED in one frame period increases. The power consumption of an LED in one frame period is roughly proportional to the duty ratio of the drive signal. Therefore, the power consumption of the LED in one frame period when the duty ratio of the drive signal supplied to the LED is 75% is about that of the case where the duty ratio of the drive signal supplied to the LED is 100%. It will be 75%.
  • FIG. 5 is a graph illustrating an example of current luminance characteristics showing the relationship between the current value of the current flowing through the LED and the brightness of the LED.
  • the brightness of the LED increases as the current value of the current flowing through the LED increases, as shown in the current brightness characteristic IY shown in FIG. Further, the power consumption of the LED increases as the current value of the current flowing through the LED increases. Therefore, the power consumption of the LED increases as the brightness of the LED increases. Therefore, the brightness of the image displayed in the image display area 22 increases as the drive current value 45s increases. Further, the power consumption of the plurality of LEDs provided in the display unit 16 increases as the drive current value 45s increases. Therefore, the power consumption of the plurality of LEDs increases as the brightness of the image displayed in the image display area 22 increases.
  • the brightness of the LED is roughly proportional to the current value of the current flowing through the LED, but it saturates as the current value of the current flowing through the LED approaches the maximum current value. Therefore, the luminous efficiency of the LED decreases as the current value of the current flowing through the LED approaches the maximum current value. Therefore, the luminous efficiency of the plurality of LEDs provided in the display unit 16 decreases as the drive current value 45s approaches the maximum drive current value.
  • FIGS. 6 and 7 are flowcharts illustrating a flow of power saving control executed by the LED display device of the first embodiment.
  • steps S1 to S14 shown in FIGS. 6 and 7 are executed.
  • Steps S4 to S14 are executed for each frame constituting the video represented by the input video signal.
  • step S1 the user sets the power saving control target value 48.
  • the user sets the power saving control target value PWt as the power saving control target value 48.
  • the set power saving control target value PWt indicates the upper limit of the power consumption of the LED display device 1 when the LED display device 1 is made to execute the power saving operation.
  • the set power saving control target value PWt is input to the power saving control target value input unit 13.
  • the luminance correction coefficient calculation circuit 33 sets the threshold value 49 based on the input power saving control target value 48.
  • the power consumption of the LED display device 1 is 48 or less, which is the power saving control target value, when the luminance information 42 to be calculated later is the threshold value 49 or less for the calculation of n kinds of luminance correction coefficients 47.
  • a threshold value 49 for calculating n kinds of luminance correction coefficients 47 is set so as to be.
  • the luminance correction coefficient calculation circuit 33 uses the average pixel value AveRGB indicating the average of a plurality of pixel values 43 as the luminance information 42, and the LED display device when the average pixel value AveRGB is equal to or less than the threshold value Tp.
  • the threshold value Tp is set so that the power consumption of 1 is equal to or less than the power saving control target value PWt, and the set threshold value Tp is used as the threshold value 49 for calculating the n types of luminance correction coefficients 47.
  • the total number of pixels indicating the number of the plurality of pixels 21 is num, and the pixel values indicating the brightness of the R LED, the G LED, and the B LED provided in the i-th pixel included in the plurality of pixels 21 are Ri, respectively.
  • Gi and Bi are used, the average pixel value AveRGB is expressed by (Equation 1).
  • 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.
  • the power consumption of the LED display device 1 when the average pixel value AveRGB has a maximum pixel value of 255 is PWaall
  • the power consumption of the LED display device 1 when the average pixel value AveRGB has a minimum pixel value of 0 is PW0.
  • the threshold Tp satisfies (Equation 2).
  • step S3 the video signal is input to the input terminal 11. Further, the video signal processing circuit 12 processes the input video signal to obtain the processed video signal 41. The obtained video signal 41 is input to the luminance information calculation circuit 31 and the correction calculation circuit 34.
  • the luminance information calculation circuit 31 calculates the luminance information 42 from the video signal 41.
  • the luminance information calculation circuit 31 uses the average pixel value AveRGB indicating the average of the plurality of pixel values 43 included in the video signal 41 as the luminance information 42. Further, the luminance information calculation circuit 31 inputs the calculated luminance information 42 to the drive current value selection circuit 32 and the luminance correction coefficient calculation circuit 33.
  • the luminance correction coefficient calculation circuit 33 determines whether or not the calculated luminance information 42 is larger than the threshold value 49 for calculating the n types of luminance correction coefficients 47.
  • the luminance correction coefficient calculation circuit 33 determines whether or not the average pixel value AveRGB is larger than the threshold value Tp. If it is determined that the average pixel value AveRGB is equal to or less than the threshold value Tp, step S8 is executed after step S6 is executed. If it is determined that the average pixel value AveRGB is larger than the threshold value Tp, step S8 is executed after step S7 is executed.
  • the first luminance correction coefficient calculation circuit 33a assigns a value that does not change the luminance of the plurality of LEDs provided in the display unit 16 to the first luminance correction coefficient.
  • the first luminance correction coefficient calculation circuit 33a assigns 1 to the first luminance correction coefficient.
  • the first luminance correction coefficient is multiplied by the plurality of pixel values 43 included in the video signal 41. Therefore, when 1 is assigned to the first brightness correction coefficient, the video signal 41 is not corrected for the brightness of the plurality of LEDs when the video signal 41 is corrected by the first brightness correction coefficient. It is the same as that of the case. That is, the brightness of the video displayed on the display unit 16 when the video signal 41 is corrected by the first luminance correction coefficient is the same as that when the video signal 41 is not corrected.
  • the first luminance correction coefficient calculation circuit 33a calculates the first luminance correction coefficient, and the first luminance correction is performed to reduce the brightness of the plurality of LEDs provided in the display unit 16. Assign to a coefficient.
  • the first luminance correction coefficient calculation circuit 33a assigns a value smaller than 1 to the first luminance correction coefficient.
  • the first luminance correction coefficient is multiplied by the plurality of pixel values 43 included in the video signal 41. Therefore, when a value smaller than 1 is assigned to the first brightness correction coefficient, the video signal 41 corrects the brightness of the plurality of LEDs when the video signal 41 is corrected by the first brightness correction coefficient. Lower than that if not done. That is, the brightness of the video displayed on the display unit 16 when the video signal 41 is corrected by the first brightness correction coefficient is lower than that when the video signal 41 is not corrected.
  • the brightness correction control circuit 14 can always set the power consumption PWa of the LED display device 1 to the power saving control target value PWt or less.
  • FIG. 8 is a graph illustrating the relationship between the average pixel value AveRGB calculated by the LED display device of the first embodiment and the first luminance correction coefficient calculated by the LED display device.
  • the first luminance correction coefficient becomes 1 when the average pixel value AveRGB is equal to or less than the threshold value Tp, and the average pixel value AveRGB becomes. Is less than 1 when is greater than the threshold Tp.
  • the first luminance correction coefficient calculation circuit 33a when the average pixel value AveRGB is larger than the threshold value Tp, the first luminance correction coefficient becomes smaller as the average pixel value AveRGB becomes larger. , Calculate the first luminance correction coefficient. Therefore, as shown in FIG. 8, the first luminance correction coefficient becomes smaller as the average pixel value AveRGB approaches the maximum pixel value 255 from the threshold value Tp.
  • the first luminance correction coefficient calculation circuit 33a averages a plurality of pixel values 51 included in the corrected video signal 50 when the average pixel value AveRGB is larger than the threshold value Tp.
  • the first luminance correction coefficient is calculated so that the average pixel value indicating is the threshold value Tp.
  • the first luminance correction coefficient calculation circuit 33a reads out a calculation formula, a table, etc. stored in a memory or the like, and calculates using the read calculation formula, the table, etc. It can be executed by executing.
  • the first luminance correction coefficient Mula can be calculated by (Equation 4).
  • step S8 the drive current value selection circuit 32 determines whether or not the calculated luminance information 42 is equal to or greater than the threshold value 46 for selecting the drive current value 45s.
  • the drive current value selection circuit 32 uses the threshold value Tc as the threshold value 46 for selecting the drive current value 45s, and determines whether or not the average pixel value AveRGB is equal to or greater than the threshold value Tc. If it is determined that the average pixel value AveRGB is smaller than the threshold value Tc, step S14 is executed after steps S9 and S10 are executed. If it is determined that the average pixel value AveRGB is equal to or greater than the threshold value Tc, step S14 is executed after steps S11, S12, and S13 are executed.
  • the drive current value selection circuit 32 selects the first drive current values IRa, IGa and IBa from the two types of set drive current values.
  • the first drive current values IRa, IGa and IBa selected are the initial drive current values used when the power consumption of the LED display device 1 is not suppressed.
  • the selected first drive current values IRa, IGa and IBa are input to the correction calculation circuit 34 and the drive circuit 15.
  • the correction calculation circuit 34 corrects the video signal 41 with the first luminance correction coefficient corresponding to the first drive current values IRa, IGa and IBa.
  • the correction calculation circuit 34 corrects the video signal 41 by multiplying the plurality of pixel values 43 included in the video signal 41 by the first luminance correction coefficient.
  • the corrected video signal 50 is input to the drive circuit 15.
  • the drive current value selection circuit 32 selects the second drive current values IRb, IGb, and IBb from the two types of set drive current values.
  • the second drive current values IRb, IGb and IBb selected are additional drive current values smaller than the initial drive current value used when the power consumption of the LED display device 1 is suppressed.
  • the selected second drive current values IRb, IGb and IBb are input to the correction calculation circuit 34 and the drive circuit 15.
  • the second luminance correction coefficient calculation circuit 33b calculates the second luminance correction coefficient, and sets the value for lowering the brightness of the plurality of LEDs provided in the display unit 16 as the second luminance correction coefficient. Assign to.
  • the second luminance correction coefficient calculation circuit 33b assigns a value smaller than 1 to the second luminance correction coefficient.
  • the second luminance correction coefficient is multiplied by the plurality of pixel values 43 included in the video signal 41. Therefore, when a value smaller than 1 is assigned to the second brightness correction coefficient, the video signal 41 corrects the brightness of the plurality of LEDs when the video signal 41 is corrected by the second brightness correction coefficient. Lower than that if not done. That is, the brightness of the video displayed on the display unit 16 when the video signal 41 is corrected by the second brightness correction coefficient is lower than that when the video signal 41 is not corrected.
  • the correction calculation circuit 34 corrects the video signal 41 with the second luminance correction coefficient.
  • the correction calculation circuit 34 corrects the video signal 41 by the second luminance correction coefficient by multiplying the plurality of pixel values 43 included in the video signal 41 by the second luminance correction coefficient. ..
  • the corrected video signal 50 is input to the drive circuit 15.
  • FIG. 9 is a graph illustrating 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.
  • the second luminance correction coefficient becomes smaller than 1 when the average pixel value AveRGB is larger than the threshold value Tc.
  • a plurality of display units 16 provided when the video signal 41 is corrected by the second luminance correction coefficient.
  • the brightness of the LED in the ON period is higher than the brightness of the plurality of LEDs in the ON period when the video signal 41 is corrected by the first luminance correction coefficient.
  • the second luminance correction coefficient calculation circuit 33b is such that when the average pixel value AveRGB is equal to or greater than the threshold value Tc, the second luminance correction coefficient becomes smaller as the average pixel value AveRGB becomes larger. , The second luminance correction coefficient is calculated. Therefore, as shown in FIG. 9, the second luminance correction coefficient becomes smaller as the average pixel value AveRGB approaches the maximum pixel value 255 from the threshold value Tc.
  • the second luminance correction coefficient calculation circuit 33b calculates the second luminance correction coefficient so that the average pixel value indicating the average of the plurality of pixel values 43 included in the corrected video signal 50 becomes the threshold value Tc. ..
  • the second luminance correction coefficient calculation circuit 33b reads out a calculation formula, a table, etc. stored in a memory or the like, and calculates using the read calculation formula, the table, etc. It can be executed by executing.
  • the first luminance correction coefficient calculation circuit 33a assigns a value smaller than 1 to the first luminance correction coefficient when the average pixel value AveRGB is larger than the threshold value Tp and smaller than the threshold value Tc. Further, the second luminance correction coefficient calculation circuit 33b assigns a value smaller than 1 to the second luminance correction coefficient when the average pixel value AveRGB is equal to or more than the threshold value Tc. Therefore, when the average pixel value AveRGB is larger than the threshold value Tp, the luminance correction coefficient calculation circuit 33 is a display unit when the video signal 41 is corrected by each of the first luminance correction coefficient and the second luminance correction coefficient. The first luminance correction coefficient and the second luminance correction coefficient are calculated so that the luminance of the plurality of LEDs provided in 16 during the on period is smaller than that when the video signal 41 is not corrected.
  • the second luminance correction coefficient Mulb can be calculated by (Equation 5).
  • a drive current having a duty ratio corresponding to the first drive current values IRa, IGa and IBa, and the maximum pixel value 255 is supplied to a plurality of LEDs provided in the display unit 16. Then, the plurality of LEDs are all turned on, and the brightness YRa, YGa and YBa of the plurality of LEDs are measured by a measuring instrument (not shown). Further, a drive current having a duty ratio corresponding to the second drive current values IRb, IGb and IBb and the maximum pixel value 255 is supplied to the plurality of LEDs to fully turn on the plurality of LEDs, and the plurality of LEDs are all lit. The brightness of the LEDs YRb, YGb and YBb is measured by a measuring instrument (not shown).
  • the brightness YRTa, YGTa and YBTa of the plurality of LEDs provided in the display unit 16 when the average pixel value AveRGB is the threshold value Tp are determined by using the measured brightness YRa, YGa and YBa and the threshold value Tp (Equation 6). Represented by.
  • the threshold value Tc is set so as to satisfy (Equation 7).
  • the video signal 41 is corrected by the first luminance correction coefficient, and a plurality of display units 16 are provided with the first drive current values IRa, IGa, and IBa.
  • the brightness of the plurality of LEDs when the LEDs are driven and the video signal 41 are corrected by the second brightness correction coefficient and the plurality of LEDs are driven by the second drive current values IRb, IGb and IBb.
  • the brightness of the plurality of LEDs matches when the average pixel value AveRGB is the threshold Tc. Therefore, when the drive current value 45s is switched between the first drive current values IRa, IGa and IBa and the second drive current values IRb, IGb and IBb, the brightness of the plurality of LEDs is discontinuous. Does not change.
  • the first drive current values IRa, IGa and IBa, and the second drive current values IRb, IGb and IBb satisfy the relationship (IRb, IGb, IBb) ⁇ (IRa, IGa, IBa). Therefore, the luminance YRa, YGa and YBa, and the luminance YRb, YGb and YBb satisfy the relationship (YRa, YGa, YBa) ⁇ (YRa, YGa, YBa). Therefore, the thresholds Tp and Tc satisfy the relationship Tp ⁇ Tc.
  • a drive current having a duty ratio corresponding to the second drive current values IRb, IGb and IBb, and the maximum pixel value 255 was supplied to the plurality of LEDs provided in the display unit 16, and the plurality of LEDs were all lit.
  • the power consumption of the LED display device 1 in this case is PWball
  • the plurality of LEDs have a duty ratio corresponding to the second drive current values IRb, IGb and IBb, and the average pixel value AveRGB corresponding to the threshold Tc.
  • the power consumption PWb of the LED display device 1 when the drive current is supplied and the plurality of LEDs are all lit is represented by (Equation 8).
  • the power consumptions PWb and PWt satisfy the relationship of PWb ⁇ PWt.
  • step S14 the drive circuit 15 drives a plurality of LEDs provided in the display unit 16 with the input drive current value 45s according to the input video signal 41.
  • the display unit 16 displays the image corresponding to the corrected image signal 50.
  • the displayed image has a brightness corresponding to the drive current value of 45 s.
  • a plurality of LEDs provided in the display unit 16 are driven by a drive current value 45s selected based on the luminance information 42. Therefore, the plurality of LEDs can be driven with a drive current value of 45 s that increases the luminous efficiency of the plurality of LEDs.
  • the video signal 41 is corrected by the luminance correction coefficient 47s according to the selected drive current value 45s. Therefore, while driving the plurality of LEDs with a drive current value of 45 s that increases the luminous efficiency of the plurality of LEDs provided in the display unit 16, the deterioration of the image quality of the LED display device 1 related to the brightness of the plurality of LEDs is deteriorated. It can be suppressed.
  • the threshold value Tp is set so that the power consumption PWa of the LED display device 1 is equal to or less than the power saving control target value PWt. ..
  • the video signal 41 is corrected by the first luminance correction coefficient or the second luminance correction coefficient to which a value smaller than 1 is assigned, and a plurality of the display unit 16 is provided. The brightness of the LED is lowered. Therefore, the power consumption PWa of the LED display device 1 can be set to the power saving control target value PWt or less.
  • the video signal 41 is corrected by the first luminance correction coefficient, and a plurality of LEDs provided in the display unit 16 are driven by the first drive current values IRa, IGa and IBa.
  • the brightness of the plurality of LEDs in the case and the brightness of the plurality of LEDs when the video signal 41 is corrected by the second brightness correction coefficient and the plurality of LEDs are driven by the second drive current values IRb, IGb and IBb.
  • the drive current value 45s is the initial drive current from the first drive current value which is the initial drive current value. It is switched to a second drive current value, which is an additional drive current value smaller than the value. As a result, it is possible to prevent the drive current value 45s from approaching the maximum drive current value at which the luminous efficiency of the LED is lowered, and it is possible to suppress the power consumption of the LED display device 1.
  • the drive current value 45s is changed from the first drive current value to a second drive current value smaller than that.
  • the brightness correction coefficient 47s is changed from the first brightness correction coefficient to a second brightness correction coefficient larger than that.
  • the video signal 41 It is assumed that the maximum pixel value 255 included in is converted to the pixel value 242 included in the corrected video signal 50. In this case, the video signal 41 has 255 gradations, and the corrected video signal 50 has 243 gradations. However, when the drive current value 45s is not changed and only the luminance correction coefficient 47s is changed, the corrected video signal 50 has only 164 gradations.
  • the drive current value 45s is not changed and only the brightness correction coefficient 47s is changed, the drive current value 45s is changed and the brightness correction coefficient 47s is changed as compared with the case where the brightness correction coefficient 47s is changed.
  • the dynamic range of the image displayed on the display unit 16 is reduced, causing visual problems such as crushed output gradation.

Abstract

This invention suppresses image quality deterioration of an LED display device while suppressing power consumption of the LED display device. The LED display device comprises: a brightness information computation unit; a drive current value selection unit; a brightness correction coefficient computation unit; a correction computation unit; a display unit; and a drive circuit. The brightness information computation unit computes brightness information from a video signal. The drive current value selection unit selects, on the basis of the brightness information, a drive current value from n types of drive current values. n is an integer of at least 2. The brightness correction coefficient computation unit computes, on the basis of the brightness information, n types of brightness correction coefficients corresponding respectively to the n types of drive current values. The correction computation unit obtains a corrected video signal by correcting a video signal using a brightness correction coefficient corresponding to the drive current value. The display unit comprises a plurality of LEDs. The drive circuit drives the plurality of LEDs with the selected drive current value, in accordance with the corrected video signal.

Description

ＬＥＤ表示装置LED display device
　本発明は、ＬＥＤ表示装置に関する。 The present invention relates to an LED display device.
　発光ダイオード（ＬＥＤ：Light Emitting Diode）表示装置は、複数のＬＥＤを備える表示部を備える。ＬＥＤ表示装置は、ＬＥＤの技術発展及び低コスト化にともない、屋内及び屋外における広告表示等に広く使用されるようになってきている。 A light emitting diode (LED: Light Emitting Diode) display device includes a display unit including a plurality of LEDs. With the technological development and cost reduction of LEDs, LED display devices have come to be widely used for displaying advertisements indoors and outdoors.
　ＬＥＤ表示装置は、かつては、自然画、アニメーション等の動画像を表示するために主に使用されていた。しかし、最近では、ＬＥＤ表示装置の画素ピッチが狭くなりＬＥＤ表示装置の視認距離が短くなってきているため、ＬＥＤ表示装置が、屋内において会議画像、監視画像等を表示するために使用されるようになってきている。 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 to display a conference image, a surveillance image, etc. indoors. Is becoming.
　特許文献１に記載された表示装置においては、画像データに基づいて、表示パネルの表示を行う場合に全画素に流れるパネル電流が予測される（段落００１２）。また、予測されたパネル電流が設定値を超える場合には、設定されたコントラストまたはブライトネスが補正される（段落００１５）。また、予測されたパネル電流が小さい場合は、コントラストまたはブライトネスが設定通りにされる（段落００１６）。これにより、実際のパネル電流が最大パネル電流以下に抑制される（段落００１５－００１６）。 In the display device described in Patent Document 1, the panel current flowing through all the pixels is predicted when the display panel is displayed based on the image data (paragraph 0012). Further, when the predicted panel current exceeds the set value, the set contrast or brightness is corrected (paragraph 0015). Also, 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).
特開２００４－３０９８１０号公報Japanese Unexamined Patent Publication No. 2004-309810
　特許文献１に記載された表示装置において採用された電力の制御と同様の電力の制御がパルス幅変調（ＰＷＭ：Pulse Width Modulation）方式のＬＥＤ表示装置において採用された場合は、ＬＥＤ表示装置の消費電力を抑制するためにコントラスト、ブライトネス等の補正等の映像信号処理が行われたときに、表示される映像のダイナミックレンジが縮小する等の画質の劣化が生じる。 When the same power control as the power control adopted in the display device described in Patent Document 1 is adopted in the pulse width modulation (PWM) type LED display device, the consumption of the LED display device is consumed. When video signal processing such as correction of contrast, brightness, etc. is performed in order to suppress power consumption, deterioration of image quality such as reduction of the dynamic range of the displayed video occurs.
　本発明は、この問題に鑑みてなされた。本発明は、ＬＥＤ表示装置の消費電力を抑制しながら、ＬＥＤ表示装置の画質の劣化を抑制することを目的とする。 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.
　本発明は、ＬＥＤ表示装置に関する。 The present invention relates to an LED display device.
　ＬＥＤ表示装置は、輝度情報演算部、駆動電流値選択部、輝度補正係数演算部、補正演算部、表示部及び駆動回路を備える。 The LED display device includes a luminance information calculation unit, a drive current value selection unit, a luminance correction coefficient calculation unit, a correction calculation unit, a display unit, and a drive circuit.
　輝度情報演算部は、映像信号から輝度情報を演算する。 The luminance information calculation unit calculates the luminance information from the video signal.
　駆動電流値選択部は、輝度情報に基づいてｎ種類の駆動電流値から駆動電流値を選択する。ｎは、２以上の整数である。 The drive current value selection unit selects a drive current value from n types of drive current values based on the brightness information. n is an integer of 2 or more.
　輝度補正係数演算部は、輝度情報に基づいてｎ種類の駆動電流値にそれぞれ対応するｎ種類の輝度補正係数を演算する。 The brightness correction coefficient calculation unit calculates n types of brightness correction coefficients corresponding to each of n types of drive current values based on the brightness information.
　補正演算部は、駆動電流値に対応する輝度補正係数により映像信号を補正して補正された映像信号を得る。 The correction calculation unit corrects the video signal with the brightness correction coefficient corresponding to the drive current value and obtains the corrected video signal.
　表示部は、複数のＬＥＤを備える。 The display unit is equipped with a plurality of LEDs.
　駆動回路は、補正された映像信号にしたがって、選択された駆動電流値で複数のＬＥＤを駆動する。 The drive circuit drives a plurality of LEDs with a selected drive current value according to the corrected video signal.
　本発明によれば、輝度情報に基づいて選択された駆動電流値で複数のＬＥＤが駆動される。このため、複数のＬＥＤの発光効率が高くなる駆動電流値で複数のＬＥＤを駆動することができる。 According to the present invention, a plurality of LEDs are driven by a drive current value selected based on the luminance information. Therefore, it is possible to drive the plurality of LEDs with a drive current value that increases the luminous efficiency of the plurality of LEDs.
　また、本発明によれば、選択された駆動電流値に応じた輝度補正係数により映像信号が補正される。このため、複数のＬＥＤの発光効率が高くなる駆動電流値で複数のＬＥＤを駆動しながら、複数のＬＥＤの輝度に関連するＬＥＤ表示装置の画質の劣化を抑制することができる。 Further, according to the present invention, the video signal is corrected by the luminance correction coefficient according to the selected drive current value. Therefore, it is possible to suppress deterioration of the image quality of the LED display device related to the brightness of the plurality of LEDs while driving the plurality of LEDs with a drive current value that increases the luminous efficiency of the plurality of LEDs.
　これらにより、ＬＥＤ表示装置の消費電力を抑制しながら、ＬＥＤ表示装置の画質の劣化を抑制することができる。 With these, 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.
　本発明の目的、特徴、局面及び利点は、以下の詳細な説明と添付図面とによって、より明白となる。 The objects, features, aspects and advantages of the present invention will be made clearer by the following detailed description and accompanying drawings.
実施の形態１の発光ダイオード（ＬＥＤ：Light Emitting Diode）表示装置を図示するブロック図である。It is a block diagram which illustrates the light emitting diode (LED: Light Emitting Diode) display device of Embodiment 1. FIG. 実施の形態１のＬＥＤ表示装置の映像表示エリアの別例を図示する平面図である。It is a top view which shows another example of the image display area of the LED display device of Embodiment 1. FIG. 実施の形態１のＬＥＤ表示装置が扱う信号及び情報を説明する図である。It is a figure explaining the signal and information handled by the LED display device of Embodiment 1. FIG. 実施の形態１のＬＥＤ表示装置が行うＰＷＭ駆動を説明するタイミングチャートである。It is a timing chart explaining the PWM drive performed by the LED display device of Embodiment 1. ＬＥＤに流れる電流の電流値とＬＥＤの輝度との関係を示す電流輝度特性の例を図示するグラフである。It is a graph which illustrates the example of the current luminance characteristic which shows the relationship between the current value of the current flowing through LED, and the luminance of LED. 実施の形態１のＬＥＤ表示装置が実行する省電力制御の流れを図示するフローチャートである。It is a flowchart which illustrates the flow of the power saving control executed by the LED display device of Embodiment 1. FIG. 実施の形態１のＬＥＤ表示装置が実行する省電力制御の流れを図示するフローチャートである。It is a flowchart which illustrates the flow of the power saving control executed by the LED display device of Embodiment 1. FIG. 実施の形態１のＬＥＤ表示装置が演算した平均画素値AveRGBと当該ＬＥＤ表示装置が演算した第１の輝度補正係数との関係を図示するグラフである。6 is a graph illustrating the relationship between the average pixel value AveRGB calculated by the LED display device of the first embodiment and the first luminance correction coefficient calculated by the LED display device. 実施の形態１のＬＥＤ表示装置が演算した平均画素値AveRGBと当該ＬＥＤ表示装置が演算した第２の輝度補正係数との関係を図示するグラフである。It is a graph which shows the relationship between the average pixel value AveRGB calculated by the LED display device of Embodiment 1 and the second luminance correction coefficient calculated by the LED display device.
　１　実施の形態１
　１．１　ＬＥＤ表示装置
　図１は、実施の形態１の発光ダイオード（ＬＥＤ：Light Emitting Diode）表示装置を図示するブロック図である。 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.
　図１に図示される実施の形態１のＬＥＤ表示装置１は、外部から入力された映像信号に応じた映像を表示する。また、ＬＥＤ表示装置１は、ＬＥＤ表示装置１の消費電力が外部から入力された省電力制御目標値以下となるように省電力制御を行う。 The LED display device 1 of the first embodiment illustrated in FIG. 1 displays an image corresponding 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 is equal to or less than the power saving control target value input from the outside.
　ＬＥＤ表示装置１は、入力端子１１、映像信号処理回路１２、省電力制御目標値入力部１３、輝度補正制御回路１４、駆動回路１５及び表示部１６を備える。 The LED display device 1 includes an input terminal 11, a video signal processing circuit 12, a power saving control target value input unit 13, a luminance correction control circuit 14, a drive circuit 15, and a display unit 16.
　表示部１６は、複数の画素２１を備える。実施の形態１においては、複数の画素２１に含まれる各画素２１ｉは、ＬＥＤ表示素子からなる。ＬＥＤ表示素子は、互いに異なる複数の発光色をそれぞれ有する複数のＬＥＤを備える。このため、表示部１６は、複数のＬＥＤを備える。互いに異なる複数の発光色は、赤（Ｒ）、緑（Ｇ）及び青（Ｂ）である。 The display unit 16 includes a plurality of pixels 21. In the first embodiment, each pixel 21i included in the plurality of pixels 21 is composed of an LED display element. The LED display element includes a plurality of LEDs having a plurality of emission colors different from each other. Therefore, the display unit 16 includes a plurality of LEDs. The plurality of emission colors different from each other are red (R), green (G), and blue (B).
　入力端子１１には、映像信号が入力される。 A video signal is input to the input terminal 11.
　映像信号処理回路１２は、入力された映像信号に対して処理を行って処理された映像信号を得る。行われる処理は、ガンマ補正等である。 The video signal processing circuit 12 processes the input video signal to obtain the processed video signal. The processing to be performed is gamma correction or the like.
　省電力制御目標値入力部１３には、省電力制御目標値が入力される。入力される省電力制御目標値は、ＬＥＤ表示装置１の消費電力の上限を示す。 The power saving control target value is input to the power saving control target value input unit 13. The input power saving control target value indicates the upper limit of the power consumption of the LED display device 1.
　輝度補正制御回路１４は、処理された映像信号を補正して補正された映像信号を得る。また、輝度補正制御回路１４は、処理された映像信号に基づいて表示部１６に備えられる複数のＬＥＤの駆動電流値を決定する。また、輝度補正制御回路１４は、ＬＥＤ表示装置１の消費電力が入力された省電力制御目標値以下となるように、処理された映像信号を補正し、複数のＬＥＤの駆動電流値を決定する。 The brightness correction control circuit 14 corrects the processed video signal and obtains the corrected video signal. Further, the luminance correction control circuit 14 determines the drive current values of a plurality of LEDs provided in the display unit 16 based on the processed video signal. Further, the brightness correction control circuit 14 corrects the processed video signal so that the power consumption of the LED display device 1 is equal to or less than the input power saving control target value, and determines the drive current values of the plurality of LEDs. ..
　駆動回路１５は、補正された映像信号にしたがって、決定された駆動電流値で表示部１６に備えられる複数のＬＥＤを駆動する。 The drive circuit 15 drives a plurality of LEDs provided in the display unit 16 with a determined drive current value according to the corrected video signal.
　表示部１６に備えられる複数のＬＥＤは、補正された映像信号、及び決定された駆動電流値に応じた輝度で発光する。これにより、表示部１６は、補正された映像信号、及び決定された駆動電流値に応じた映像を表示する。 The plurality of LEDs provided in the display unit 16 emit light with a brightness corresponding to the corrected video signal and the determined drive current value. As a result, the display unit 16 displays the corrected video signal and the video corresponding to the determined drive current value.
　輝度補正制御回路１４及び駆動回路１５は、補正された映像信号により表現される映像を構成する各フレーム画像の輝度及び／又はダイナミックレンジを補正する。また、表示部１６は、輝度及び／又はダイナミックレンジが補正された各フレーム画像を順次に表示することにより映像を表示する。 The luminance correction control circuit 14 and the drive circuit 15 correct the luminance and / or dynamic range of each frame image constituting the image represented by the corrected image signal. Further, the display unit 16 displays an image by sequentially displaying each frame image whose brightness and / or dynamic range has been corrected.
　１．２　表示部
　表示部１６は、図１に図示されるように、複数の画素２１を備える。図１には、複数の画素２１が横方向４画素×縦方向４画素の１６画素である場合が図示されている。また、表示部１６は、映像表示エリア２２を有する。複数の画素２１は、映像表示エリア２２に配置される。複数の画素２１は、マトリクス状に配列される。 1.2 Display unit The display unit 16 includes a plurality of pixels 21 as shown in FIG. FIG. 1 shows a case where the plurality of pixels 21 are 16 pixels of 4 pixels in the horizontal direction and 4 pixels in the vertical direction. In addition, the display unit 16 has a video display area 22. The plurality of pixels 21 are arranged in the video display area 22. The plurality of pixels 21 are arranged in a matrix.
　図２は、実施の形態１のＬＥＤ表示装置の映像表示エリアの別例を図示する平面図である。 FIG. 2 is a plan view illustrating another example of the image display area of the LED display device of the first embodiment.
　図２に図示される映像表示エリア２３は、表示部１６が横方向１９２０画素×縦方向１０８０画素の入力解像度を有する場合の映像表示エリアである。このため、図２に図示される映像表示エリア２３には、横方向１９２０画素×縦方向１０８０画素の１９８０×１０８０画素が配列される。 The image display area 23 illustrated in FIG. 2 is an image display area when the display unit 16 has an input resolution of 1920 pixels in the horizontal direction and 1080 pixels in the vertical direction. Therefore, in the image display area 23 shown in FIG. 2, 1980 × 1080 pixels of 1920 pixels in the horizontal direction × 1080 pixels in the vertical direction are arranged.
　１．３　輝度補正制御回路及び駆動回路
　図３は、実施の形態１のＬＥＤ表示装置が扱う信号及び情報を説明する図である。 1.3 Luminance correction control circuit and drive circuit FIG. 3 is a diagram illustrating signals and information handled by the LED display device of the first embodiment.
　ＬＥＤ表示装置１は、図１に図示されるように、輝度情報演算回路３１、駆動電流値選択回路３２、輝度補正係数演算回路３３及び補正演算回路３４を備える。輝度情報演算回路３１、駆動電流値選択回路３２、輝度補正係数演算回路３３及び補正演算回路３４は、輝度補正制御回路１４に備えられる。輝度補正制御回路１４、輝度情報演算回路３１、駆動電流値選択回路３２、輝度補正係数演算回路３３及び補正演算回路３４は、それぞれ輝度補正制御部、輝度情報演算部、駆動電流値選択部、輝度補正係数演算部及び補正演算部を構成する回路である。輝度補正制御部、輝度情報演算部、駆動電流値選択部、輝度補正係数演算部及び補正演算部の全部又は一部が、プログラムを実行するコンピューターにより構成されてもよい。 As shown in FIG. 1, the LED display device 1 includes a luminance information calculation circuit 31, a drive current value selection circuit 32, a luminance correction coefficient calculation circuit 33, and a correction calculation circuit 34. The brightness information calculation circuit 31, the drive current value selection circuit 32, the brightness correction coefficient calculation circuit 33, and the correction calculation circuit 34 are provided in the brightness correction control circuit 14. The brightness correction control circuit 14, the brightness information calculation circuit 31, the drive current value selection circuit 32, the brightness correction coefficient calculation circuit 33, and the correction calculation circuit 34 are the brightness correction control unit, the brightness information calculation unit, the drive current value selection unit, and the brightness, respectively. This is a circuit that constitutes a correction coefficient calculation unit and a correction calculation unit. All or part of the luminance correction control unit, the luminance information calculation unit, the drive current value selection unit, the luminance correction coefficient calculation unit, and the correction calculation unit may be configured by a computer that executes the program.
　輝度情報演算回路３１は、図３に図示される映像信号４１から図３に図示される輝度情報４２を演算する。映像信号４１は、映像信号処理回路１２により処理された映像信号であり、映像信号処理回路１２から入力される。演算される輝度情報４２は、表示部１６に備えられる複数のＬＥＤの輝度を示す。 The luminance information calculation circuit 31 calculates the luminance information 42 shown in FIG. 3 from the video signal 41 shown in FIG. The video signal 41 is a video signal processed by the video signal processing circuit 12, and is input from the video signal processing circuit 12. The calculated luminance information 42 indicates the luminance of a plurality of LEDs provided in the display unit 16.
　映像信号４１は、複数の画素２１の輝度をそれぞれ示す複数の画素値を含む。実施の形態１においては、各画素２１ｉの輝度を示す輝度値は、各画素２１ｉに備えられるＲのＬＥＤ、ＧのＬＥＤ及びＢのＬＥＤの輝度を示す画素値を含む。このため、映像信号４１は、表示部１６に備えられる複数のＬＥＤの輝度をそれぞれ示す複数の画素値４３を含む。複数の画素値４３は、映像信号４１に含まれる輝度信号に含まれる。また、輝度情報４２は、複数の画素値４３の総和又は平均４４を含む。 The video signal 41 includes a plurality of pixel values indicating the brightness of each of the plurality of pixels 21. In the first embodiment, the brightness value indicating the brightness of each pixel 21i includes the pixel value indicating the brightness of the R LED, the G LED, and the B LED provided in each pixel 21i. Therefore, the video signal 41 includes a plurality of pixel values 43 indicating the brightness of each of the plurality of LEDs provided in the display unit 16. The plurality of pixel values 43 are included in the luminance signal included in the video signal 41. Further, the luminance information 42 includes the sum or average 44 of the plurality of pixel values 43.
　駆動電流値選択回路３２は、演算された輝度情報４２に基づいて、図３に図示されるｎ種類の駆動電流値４５から図３に図示される駆動電流値４５ｓを選択する。ｎは、２以上の整数である。ｎ種類の駆動電流値４５は、初期の駆動電流値４５ａ、及び初期の駆動電流値４５ａより小さい少なくとも１種類の追加の駆動電流値４５ｂを含む。 The drive current value selection circuit 32 selects the drive current value 45s shown in FIG. 3 from the n types of drive current values 45 shown in FIG. 3 based on the calculated luminance information 42. n is an integer of 2 or more. The n types of drive current values 45 include an initial drive current value 45a and at least one additional drive current value 45b smaller than the initial drive current value 45a.
　また、駆動電流値選択回路３２は、演算された輝度情報４２と図３に図示される駆動電流値４５ｓの選択のための閾値４６との大小関係に基づいて駆動電流値４５ｓを選択する。実施の形態１においては、駆動電流値選択回路３２は、演算された総和又は平均４４と駆動電流値４５ｓの選択のための閾値４６との大小関係に基づいて駆動電流値４５ｓを選択する。 Further, the drive current value selection circuit 32 selects the drive current value 45s based on the magnitude relationship between the calculated luminance information 42 and the threshold value 46 for selecting the drive current value 45s shown in FIG. In the first embodiment, the drive current value selection circuit 32 selects the drive current value 45s based on the magnitude relationship between the calculated sum or average 44 and the threshold value 46 for selecting the drive current value 45s.
　輝度補正係数演算回路３３は、演算された輝度情報４２に基づいて、図３に図示されるｎ種類の輝度補正係数４７を演算する。実施の形態１においては、輝度補正係数演算回路３３は、演算された総和又は平均４４に基づいて、ｎ種類の輝度補正係数４７を演算する。ｎ種類の輝度補正係数４７は、それぞれｎ種類の駆動電流値４５に対応する。 The brightness correction coefficient calculation circuit 33 calculates n types of brightness correction coefficients 47 shown in FIG. 3 based on the calculated brightness information 42. In the first embodiment, the luminance correction coefficient calculation circuit 33 calculates n kinds of luminance correction coefficients 47 based on the calculated total or average 44. The n types of brightness correction coefficients 47 correspond to n types of drive current values 45, respectively.
　また、輝度補正係数演算回路３３は、図３に図示される省電力制御目標値４８に基づいて図３に図示されるｎ種類の輝度補正係数４７の演算のための閾値４９を設定する。また、輝度補正係数演算回路３３は、演算された輝度情報４２がｎ種類の輝度補正係数４７の演算のための閾値４９より大きい場合は、映像信号４１がｎ種類の輝度補正係数４７の各々により補正されたときの表示部１６に備えられる複数のＬＥＤのオン期間における輝度が、映像信号４１が補正されないときのそれより小さくなるように、ｎ種類の輝度補正係数４７を演算する。 Further, the luminance correction coefficient calculation circuit 33 sets a threshold value 49 for calculating the n types of luminance correction coefficients 47 shown in FIG. 3 based on the power saving control target value 48 shown in FIG. Further, in the luminance correction coefficient calculation circuit 33, when the calculated luminance information 42 is larger than the threshold value 49 for the calculation of the n types of luminance correction coefficients 47, the video signal 41 is based on each of the n types of luminance correction coefficients 47. The n kinds of luminance correction coefficients 47 are calculated so that the luminance of the plurality of LEDs provided in the display unit 16 when corrected is smaller than that when the video signal 41 is not corrected.
　補正演算回路３４は、選択された駆動電流値４５ｓに対応する輝度補正係数４７ｓにより映像信号４１を補正して図３に図示される補正された映像信号５０を得る。実施の形態１においては、補正演算回路３４は、複数の画素値４３に輝度補正係数４７ｓを乗算することにより映像信号４１を補正する。このため、補正された映像信号５０は、複数の画素値４３に輝度補正係数４７ｓを乗算することにより得られる、図３に図示される複数の画素値５１を含む。 The correction calculation circuit 34 corrects the video signal 41 with the luminance correction coefficient 47s corresponding to the selected drive current value 45s, and obtains the corrected video signal 50 shown in FIG. In the first embodiment, the correction calculation circuit 34 corrects the video signal 41 by multiplying the plurality of pixel values 43 by the luminance correction coefficient 47s. Therefore, the corrected video signal 50 includes the plurality of pixel values 51 shown in FIG. 3 obtained by multiplying the plurality of pixel values 43 by the luminance correction coefficient 47s.
　駆動回路１５は、補正された映像信号５０にしたがって、選択された駆動電流値４５ｓで表示部１６に備えられる複数のＬＥＤを駆動する。実施の形態１においては、駆動回路１５は、パルス幅変調（ＰＷＭ：Pulse Width Modulation）方式で表示部１６に備えられる複数のＬＥＤをＰＷＭ駆動する。駆動回路１５は、選択された駆動電流値４５ｓを有する、図３に図示される駆動信号５２を当該複数のＬＥＤに供給することにより、駆動電流値４５ｓで当該複数のＬＥＤを駆動する。したがって、駆動電流値４５ｓを変更することにより、当該複数のＬＥＤのオン期間における輝度及び１フレーム期間における平均輝度を調整することができる。また、駆動回路１５は、補正された映像信号５０に応じたデューティー比５３を有する、図３に図示される、駆動信号５２を当該複数のＬＥＤに供給することにより、補正された映像信号５０にしたがって当該複数のＬＥＤを駆動する。したがって、輝度補正係数４７ｓを変更することにより、当該複数のＬＥＤの１フレーム期間における平均輝度を調整することができる。 The drive circuit 15 drives a plurality of LEDs provided in the display unit 16 with a selected drive current value of 45 s according to the corrected video signal 50. In the first embodiment, the drive circuit 15 PWM-drives a plurality of LEDs provided in the display unit 16 by a pulse width modulation (PWM) method. The drive circuit 15 drives the plurality of LEDs at the drive current value of 45 s by supplying the drive signal 52 shown in FIG. 3 having the selected drive current value of 45 s to the plurality of LEDs. Therefore, by changing the drive current value 45s, it is possible to adjust the brightness of the plurality of LEDs during the on period and the average brightness during one frame period. Further, the drive circuit 15 has a duty ratio 53 corresponding to the corrected video signal 50, and by supplying the drive signal 52 shown in FIG. 3 to the plurality of LEDs, the corrected video signal 50 is obtained. Therefore, the plurality of LEDs are driven. Therefore, by changing the brightness correction coefficient 47s, the average brightness of the plurality of LEDs in one frame period can be adjusted.
　実施の形態１においては、ｎ種類の駆動電流値４５は、第１の駆動電流値及び第２の駆動電流値からなる２種類の駆動電流値である。第１の駆動電流値は、初期の駆動電流値４５ａである。第２の駆動電流値は、初期の駆動電流値４５ａより小さい追加の駆動電流値４５ｂである。また、ｎ種類の輝度補正係数４７は、第１の輝度補正係数及び第２の輝度補正係数からなる２種類の輝度補正係数である。第１の輝度補正係数及び第２の輝度補正係数は、それぞれ第１の駆動電流値及び第２の駆動電流値に対応する。輝度補正係数演算回路３３は、第１の輝度補正係数及び第２の輝度補正係数をそれぞれ演算する第１の輝度補正係数演算回路３３ａ及び第２の輝度補正係数演算回路３３ｂを備える。 In the first embodiment, the n types of drive current values 45 are two types of drive current values including a first drive current value and a second drive current value. The first drive current value is the initial drive current value 45a. The second drive current value is an additional drive current value 45b smaller than the initial drive current value 45a. Further, the n types of brightness correction coefficients 47 are two types of brightness correction coefficients including a first brightness correction coefficient and a second brightness correction coefficient. The first luminance correction coefficient and the second luminance correction coefficient correspond to the first drive current value and the second drive current value, respectively. The luminance correction coefficient calculation circuit 33 includes a first luminance correction coefficient calculation circuit 33a and a second luminance correction coefficient calculation circuit 33b that calculate the first luminance correction coefficient and the second luminance correction coefficient, respectively.
　１．４　ＬＥＤの輝度の制御方法
　図４は、実施の形態１のＬＥＤ表示装置が行うＰＷＭ駆動を説明するタイミングチャートである。図４（ａ）は、ＰＷＭ駆動の基本周期が経過するごとに発せられるパルスを含む信号の波形を図示する。図４（ｂ）及び図４（ｃ）は、ＬＥＤに供給される駆動信号の電流波形を図示する。 1.4 LED Luminance Control Method FIG. 4 is a timing chart illustrating the PWM drive performed by the LED display device of the first embodiment. FIG. 4A illustrates the waveform of a signal including a pulse emitted each time the basic period of PWM drive elapses. 4 (b) and 4 (c) show the current waveform of the drive signal supplied to the LED.
　図４（ａ）に図示されるＰＷＭ駆動の基本周期は、補正された映像信号５０の１フレーム期間である。図４（ｂ）及び図４（ｃ）に図示される駆動信号は、選択された駆動電流値４５ｓに一致するパルス高、及びＬＥＤの輝度を示す画素値に応じたデューティー比を駆動信号に与えるパルス幅を有する電流パルスを有する。図４（ｂ）及び図４（ｃ）に図示される駆動信号がＬＥＤに供給された場合は、駆動電流値４５ｓを有する駆動電流が当該パルス幅を有するオン期間にＬＥＤに流れる。パルス幅は、１フレーム期間以下である。図４（ｂ）に図示される電流パルスは、１００％のデューティー比を駆動信号に与えるパルス幅PWM1を有する。図４（ｃ）に図示される電流パルスは、７５％のデューティー比を駆動信号に与えるパルス幅PWM2を有する。 The basic period of PWM drive shown in FIG. 4A is one frame period of the corrected video signal 50. The drive signal illustrated in FIGS. 4 (b) and 4 (c) gives the drive signal a pulse height corresponding to the selected drive current value 45s and a duty ratio corresponding to the pixel value indicating the brightness of the LED. It has a current pulse with a pulse width. When the drive signal shown in FIGS. 4 (b) and 4 (c) is supplied to the LED, a drive current having a drive current value of 45 s flows through the LED during the on-period having the pulse width. The pulse width is one frame period or less. The current pulse illustrated in FIG. 4B has a pulse width PWM1 that gives the drive signal a duty ratio of 100%. The current pulse illustrated in FIG. 4C has a pulse width PWM2 that gives the drive signal a duty ratio of 75%.
　ＬＥＤの１フレーム期間における通電時間は、ＬＥＤに供給される駆動信号のデューティー比が小さくなるほど短くなる。このため、ＬＥＤの１フレーム期間における平均輝度は、ＬＥＤに供給される駆動信号のデューティー比が小さくなるほど低くなる。例えば、図４（ｃ）に示される７５％のデューティー比を有する駆動信号がＬＥＤに供給される場合のＬＥＤの１フレーム期間における通電時間は、図４（ｂ）に示される１００％のデューティー比を有する駆動信号がＬＥＤに供給される場合のそれよりも短くなる。また、図４（ｃ）に示される７５％のデューティー比を有する駆動信号がＬＥＤに供給される場合のＬＥＤの１フレーム期間における平均輝度は、図４（ｂ）に示される１００％のデューティー比を有する駆動信号がＬＥＤに供給される場合のそれよりも高くなる。したがって、ＬＥＤに供給される駆動信号のデューティー比を変更することにより、ＬＥＤの１フレーム期間における平均輝度を調整することができる。また、ＬＥＤに供給される駆動信号のデューティー比が小さくなるほどＬＥＤの１フレーム期間における通電時間が短くなることにより、ＬＥＤの１フレーム期間における消費電力は、ＬＥＤに供給される駆動信号のデューティー比が小さくなるほど小さくなる。例えば、図４（ｃ）に示される７５％のデューティー比を有する駆動信号がＬＥＤに供給される場合のＬＥＤの１フレーム期間における消費電力は、図４（ｂ）に示される１００％のデューティー比を有する駆動信号がＬＥＤに供給される場合のそれよりも小さくなる。 The energizing time of the LED in one frame period becomes shorter as the duty ratio of the drive signal supplied to the LED becomes smaller. Therefore, the average brightness of the LED in one frame period becomes lower as the duty ratio of the drive signal supplied to the LED becomes smaller. For example, when a drive signal having a duty ratio of 75% shown in FIG. 4 (c) is supplied to the LED, the energizing time of the LED in one frame period is the duty ratio of 100% shown in FIG. 4 (b). It is shorter than that when the drive signal having is supplied to the LED. Further, when a drive signal having a duty ratio of 75% shown in FIG. 4C is supplied to the LED, the average brightness of the LED in one frame period is the duty ratio of 100% shown in FIG. 4B. The drive signal with is higher than that when supplied to the LED. Therefore, the average brightness of the LED in one frame period can be adjusted by changing the duty ratio of the drive signal supplied to the LED. Further, as the duty ratio of the drive signal supplied to the LED becomes smaller, the energization time of the LED in one frame period becomes shorter, so that the power consumption of the LED in one frame period is the duty ratio of the drive signal supplied to the LED. The smaller it is, the smaller it becomes. For example, when a drive signal having a duty ratio of 75% shown in FIG. 4 (c) is supplied to the LED, the power consumption of the LED in one frame period is 100% duty ratio shown in FIG. 4 (b). The drive signal with is smaller than that when supplied to the LED.
　上述したように、ＬＥＤの１フレーム期間における平均輝度は、ＬＥＤに供給される駆動信号のデューティー比が小さくなるほど低くなる。また、ＬＥＤの１フレーム期間における消費電力は、ＬＥＤに供給される駆動信号のデューティー比が小さくなるほど小さくなる。したがって、映像信号４１に含まれる画素値により示されるＬＥＤの輝度が低くなるほど、ＬＥＤに供給される駆動信号のデューティー比が小さくされ、ＬＥＤの１フレーム期間における消費電力が小さくなる。一方、映像信号４１に含まれる画素値により示されるＬＥＤの輝度が高くなるほど、ＬＥＤに供給される駆動信号のデューティー比が大きくされ、ＬＥＤの１フレーム期間における消費電力が大きくなる。ＬＥＤの１フレーム期間における消費電力は、概ね駆動信号のデューティー比に比例する。このため、ＬＥＤに供給される駆動信号のデューティー比が７５％である場合のＬＥＤの１フレーム期間における消費電力は、ＬＥＤに供給される駆動信号のデューティー比が１００％である場合のそれの約７５％となる。 As described above, the average brightness of the LED in one frame period becomes lower as the duty ratio of the drive 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 drive signal supplied to the LED becomes smaller. Therefore, as the brightness of the LED indicated by the pixel value included in the video signal 41 becomes lower, the duty ratio of the drive signal supplied to the LED becomes smaller, and the power consumption of the LED in one frame period becomes smaller. On the other hand, as the brightness of the LED indicated by the pixel value included in the video signal 41 increases, the duty ratio of the drive signal supplied to the LED increases, and the power consumption of the LED in one frame period increases. The power consumption of an LED in one frame period is roughly proportional to the duty ratio of the drive signal. Therefore, the power consumption of the LED in one frame period when the duty ratio of the drive signal supplied to the LED is 75% is about that of the case where the duty ratio of the drive signal supplied to the LED is 100%. It will be 75%.
　１．５　駆動電流値と発光効率との関係
　図５は、ＬＥＤに流れる電流の電流値とＬＥＤの輝度との関係を示す電流輝度特性の例を図示するグラフである。 1.5 Relationship between drive current value and luminous efficiency FIG. 5 is a graph illustrating an example of current luminance characteristics showing the relationship between the current value of the current flowing through the LED and the brightness of the LED.
　ＬＥＤの輝度は、図５に図示される電流輝度特性ＩＹのように、ＬＥＤに流れる電流の電流値が大きくなるほど高くなる。また、ＬＥＤの消費電力は、ＬＥＤに流れる電流の電流値が大きくなるほど大きくなる。このため、ＬＥＤの消費電力は、ＬＥＤの輝度が高くなるほど大きくなる。したがって、映像表示エリア２２に表示される映像の輝度は、駆動電流値４５ｓが大きくなるほど高くなる。また、表示部１６に備えられる複数のＬＥＤの消費電力は、駆動電流値４５ｓが大きくなるほど大きくなる。このため、当該複数のＬＥＤの消費電力は、映像表示エリア２２に表示される映像の輝度が高くなるほど大きくなる。 The brightness of the LED increases as the current value of the current flowing through the LED increases, as shown in the current brightness characteristic IY shown in FIG. Further, the power consumption of the LED increases as the current value of the current flowing through the LED increases. Therefore, the power consumption of the LED increases as the brightness of the LED increases. Therefore, the brightness of the image displayed in the image display area 22 increases as the drive current value 45s increases. Further, the power consumption of the plurality of LEDs provided in the display unit 16 increases as the drive current value 45s increases. Therefore, the power consumption of the plurality of LEDs increases as the brightness of the image displayed in the image display area 22 increases.
　ＬＥＤの輝度は、ＬＥＤに流れる電流の電流値に概ね比例するが、ＬＥＤに流れる電流の電流値が最大電流値に近づくにつれて飽和する。このため、ＬＥＤの発光効率は、ＬＥＤに流れる電流の電流値が最大電流値に近づくにつれて低下する。したがって、表示部１６に備えられる複数のＬＥＤの発光効率は、駆動電流値４５ｓが最大駆動電流値に近づくにつれて低くなる。 The brightness of the LED is roughly proportional to the current value of the current flowing through the LED, but it saturates as the current value of the current flowing through the LED approaches the maximum current value. Therefore, the luminous efficiency of the LED decreases as the current value of the current flowing through the LED approaches the maximum current value. Therefore, the luminous efficiency of the plurality of LEDs provided in the display unit 16 decreases as the drive current value 45s approaches the maximum drive current value.
　１．６　省電力制御
　図６及び図７は、実施の形態１のＬＥＤ表示装置が実行する省電力制御の流れを図示するフローチャートである。 1.6 Power Saving Control FIGS. 6 and 7 are flowcharts illustrating a flow of power saving control executed by the LED display device of the first embodiment.
　省電力制御が実行される場合は、図６及び図７に図示されるステップＳ１からＳ１４までが実行される。ステップＳ４からＳ１４までは、入力された映像信号により表現される映像を構成する各フレームについて実行される。 When the power saving control is executed, steps S1 to S14 shown in FIGS. 6 and 7 are executed. Steps S4 to S14 are executed for each frame constituting the video represented by the input video signal.
　ステップＳ１においては、ユーザーが、省電力制御目標値４８を設定する。実施の形態１においては、ユーザーは、省電力制御目標値PWtを省電力制御目標値４８として設定する。設定される省電力制御目標値PWtは、ＬＥＤ表示装置１に省電力運転を実行させる際のＬＥＤ表示装置１の消費電力の上限を示す。設定された省電力制御目標値PWtは、省電力制御目標値入力部１３に入力される。 In step S1, the user sets the power saving control target value 48. In the first embodiment, the user sets the power saving control target value PWt as the power saving control target value 48. The set power saving control target value PWt indicates the upper limit of the power consumption of the LED display device 1 when the LED display device 1 is made to execute the power saving operation. The set power saving control target value PWt is input to the power saving control target value input unit 13.
　続くステップＳ２においては、輝度補正係数演算回路３３が、入力された省電力制御目標値４８に基づいて閾値４９を設定する。輝度補正係数演算回路３３は、後に演算される輝度情報４２がｎ種類の輝度補正係数４７の演算のための閾値４９以下である場合にＬＥＤ表示装置１の消費電力が省電力制御目標値４８以下となるようにｎ種類の輝度補正係数４７の演算のための閾値４９を設定する。実施の形態１においては、輝度補正係数演算回路３３は、複数の画素値４３の平均を示す平均画素値AveRGBを輝度情報４２として用い、平均画素値AveRGBが閾値Tp以下である場合にＬＥＤ表示装置１の消費電力が省電力制御目標値PWt以下となるように閾値Tpを設定し、設定した閾値Tpをｎ種類の輝度補正係数４７の演算のための閾値４９として用いる。 In the following step S2, the luminance correction coefficient calculation circuit 33 sets the threshold value 49 based on the input power saving control target value 48. In the luminance correction coefficient calculation circuit 33, the power consumption of the LED display device 1 is 48 or less, which is the power saving control target value, when the luminance information 42 to be calculated later is the threshold value 49 or less for the calculation of n kinds of luminance correction coefficients 47. A threshold value 49 for calculating n kinds of luminance correction coefficients 47 is set so as to be. In the first embodiment, the luminance correction coefficient calculation circuit 33 uses the average pixel value AveRGB indicating the average of a plurality of pixel values 43 as the luminance information 42, and the LED display device when the average pixel value AveRGB is equal to or less than the threshold value Tp. The threshold value Tp is set so that the power consumption of 1 is equal to or less than the power saving control target value PWt, and the set threshold value Tp is used as the threshold value 49 for calculating the n types of luminance correction coefficients 47.
　複数の画素２１の数を示す総画素数をnumとし、複数の画素２１に含まれるi番目の画素に備えられるＲのＬＥＤ、ＧのＬＥＤ及びＢのＬＥＤの輝度を示す画素値をそれぞれRi,Gi及びBiとした場合は、平均画素値AveRGBは、（式１）により表される。 The total number of pixels indicating the number of the plurality of pixels 21 is num, and the pixel values indicating the brightness of the R LED, the G LED, and the B LED provided in the i-th pixel included in the plurality of pixels 21 are Ri, respectively. When Gi and Bi are used, the average pixel value AveRGB is expressed by (Equation 1).
Figure JPOXMLDOC01-appb-M000001
Figure JPOXMLDOC01-appb-M000001
　画素値Ri,Gi及びBiの各々は、８ビットのビット長を有し、２５６階調を有する。したがって、平均画素値AveRGBがとりうる最大画素値は、255である。また、平均画素値AveRGBがとりうる最小画素値は、0である。 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.
　また、平均画素値AveRGBが最大画素値255をとる場合のＬＥＤ表示装置１の消費電力をPWaallとし、平均画素値AveRGBが最小画素値0をとる場合のＬＥＤ表示装置１の消費電力をPW0とした場合は、閾値Tpは（式２）を満たす。 Further, the power consumption of the LED display device 1 when the average pixel value AveRGB has a maximum pixel value of 255 is PWaall, and the power consumption of the LED display device 1 when the average pixel value AveRGB has a minimum pixel value of 0 is PW0. In that case, the threshold Tp satisfies (Equation 2).
Figure JPOXMLDOC01-appb-M000002
Figure JPOXMLDOC01-appb-M000002
　続くステップＳ３においては、映像信号が入力端子１１に入力される。また、映像信号処理回路１２が、入力された映像信号を処理し、処理された映像信号４１を得る。得られた映像信号４１は、輝度情報演算回路３１及び補正演算回路３４に入力される。 In the following step S3, the video signal is input to the input terminal 11. Further, the video signal processing circuit 12 processes the input video signal to obtain the processed video signal 41. The obtained video signal 41 is input to the luminance information calculation circuit 31 and the correction calculation circuit 34.
　続くステップＳ４においては、輝度情報演算回路３１が、映像信号４１から輝度情報４２を演算する。実施の形態１においては、輝度情報演算回路３１は、映像信号４１に含まれる複数の画素値４３の平均を示す平均画素値AveRGBを輝度情報４２として用いる。また、輝度情報演算回路３１は、演算した輝度情報４２を駆動電流値選択回路３２及び輝度補正係数演算回路３３に入力する。 In the following step S4, the luminance information calculation circuit 31 calculates the luminance information 42 from the video signal 41. In the first embodiment, the luminance information calculation circuit 31 uses the average pixel value AveRGB indicating the average of the plurality of pixel values 43 included in the video signal 41 as the luminance information 42. Further, the luminance information calculation circuit 31 inputs the calculated luminance information 42 to the drive current value selection circuit 32 and the luminance correction coefficient calculation circuit 33.
　続くステップＳ５においては、輝度補正係数演算回路３３が、演算された輝度情報４２がｎ種類の輝度補正係数４７の演算のための閾値４９より大きいか否かを判定する。実施の形態１においては、輝度補正係数演算回路３３は、平均画素値AveRGBが閾値Tpより大きいか否かを判定する。平均画素値AveRGBが閾値Tp以下であると判定された場合は、ステップＳ６が実行された後にステップＳ８が実行される。平均画素値AveRGBが閾値Tpより大きいと判定された場合は、ステップＳ７が実行された後にステップＳ８が実行される。 In the following step S5, the luminance correction coefficient calculation circuit 33 determines whether or not the calculated luminance information 42 is larger than the threshold value 49 for calculating the n types of luminance correction coefficients 47. In the first embodiment, the luminance correction coefficient calculation circuit 33 determines whether or not the average pixel value AveRGB is larger than the threshold value Tp. If it is determined that the average pixel value AveRGB is equal to or less than the threshold value Tp, step S8 is executed after step S6 is executed. If it is determined that the average pixel value AveRGB is larger than the threshold value Tp, step S8 is executed after step S7 is executed.
　ステップＳ６においては、第１の輝度補正係数演算回路３３ａが、表示部１６に備えられる複数のＬＥＤの輝度を変化させない値を第１の輝度補正係数に割り当てる。実施の形態１においては、第１の輝度補正係数演算回路３３ａは、第１の輝度補正係数に1を割り当てる。映像信号４１が第１の輝度補正係数により補正される場合は、映像信号４１に含まる複数の画素値４３に第１の輝度補正係数が乗算される。このため、第１の輝度補正係数に1が割り当てられた場合は、映像信号４１が第１の輝度補正係数により補正された場合の当該複数のＬＥＤの輝度は、映像信号４１が補正されなかった場合のそれと同じである。すなわち、映像信号４１が第１の輝度補正係数により補正された場合の表示部１６に表示される映像の輝度は、映像信号４１が補正されなかった場合のそれと同じである。 In step S6, the first luminance correction coefficient calculation circuit 33a assigns a value that does not change the luminance of the plurality of LEDs provided in the display unit 16 to the first luminance correction coefficient. In the first embodiment, the first luminance correction coefficient calculation circuit 33a assigns 1 to the first luminance correction coefficient. When the video signal 41 is corrected by the first luminance correction coefficient, the first luminance correction coefficient is multiplied by the plurality of pixel values 43 included in the video signal 41. Therefore, when 1 is assigned to the first brightness correction coefficient, the video signal 41 is not corrected for the brightness of the plurality of LEDs when the video signal 41 is corrected by the first brightness correction coefficient. It is the same as that of the case. That is, the brightness of the video displayed on the display unit 16 when the video signal 41 is corrected by the first luminance correction coefficient is the same as that when the video signal 41 is not corrected.
　一方、ステップＳ７においては、第１の輝度補正係数演算回路３３ａが、第１の輝度補正係数を演算して、表示部１６に備えられる複数のＬＥＤの輝度を低くする値を第１の輝度補正係数に割り当てる。実施の形態１においては、第１の輝度補正係数演算回路３３ａは、第１の輝度補正係数に１より小さい値を割り当てる。映像信号４１が第１の輝度補正係数により補正される場合は、映像信号４１に含まる複数の画素値４３に第１の輝度補正係数が乗算される。このため、第１の輝度補正係数に１より小さい値が割り当てられた場合は、映像信号４１が第１の輝度補正係数により補正されたときの当該複数のＬＥＤの輝度は、映像信号４１が補正されなかった場合のそれより低い。すなわち、映像信号４１が第１の輝度補正係数により補正された場合の表示部１６に表示される映像の輝度は、映像信号４１が補正されなかった場合のそれより低い。 On the other hand, in step S7, the first luminance correction coefficient calculation circuit 33a calculates the first luminance correction coefficient, and the first luminance correction is performed to reduce the brightness of the plurality of LEDs provided in the display unit 16. Assign to a coefficient. In the first embodiment, the first luminance correction coefficient calculation circuit 33a assigns a value smaller than 1 to the first luminance correction coefficient. When the video signal 41 is corrected by the first luminance correction coefficient, the first luminance correction coefficient is multiplied by the plurality of pixel values 43 included in the video signal 41. Therefore, when a value smaller than 1 is assigned to the first brightness correction coefficient, the video signal 41 corrects the brightness of the plurality of LEDs when the video signal 41 is corrected by the first brightness correction coefficient. Lower than that if not done. That is, the brightness of the video displayed on the display unit 16 when the video signal 41 is corrected by the first brightness correction coefficient is lower than that when the video signal 41 is not corrected.
　平均画素値AveRGBが最大画素値255をとる場合のＬＥＤ表示装置１の消費電力をPWaallとし、平均画素値AveRGBが最小画素値0をとる場合のＬＥＤ表示装置１の消費電力をPW0とした場合は、ＬＥＤ表示装置１の消費電力PWaは、（式３）により表される。 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).
Figure JPOXMLDOC01-appb-M000003
Figure JPOXMLDOC01-appb-M000003
　（式２）及び（式３）からは、平均画素値AveRGBが閾値Tp以下である場合は、ＬＥＤ表示装置１の消費電力PWaが省電力制御目標値PWt以下となることを理解することができる。また、（式２）及び（式３）からは、平均画素値AveRGBが閾値Tpより大きい場合は、省電力制御が行われない限り、ＬＥＤ表示装置１の消費電力PWaが省電力制御目標値PWtより大きくなることを理解することができる。このため、省電力制御は、平均画素値AveRGBが閾値Tpより大きい場合に、表示部１６に備えられる複数のＬＥＤの輝度を低くすることにより、ＬＥＤ表示装置１の消費電力PWaを省電力制御目標値PWt以下にする処理を含む。これにより、輝度補正制御回路１４は、ＬＥＤ表示装置１の消費電力PWaを常に省電力制御目標値PWt以下にすることができる。 From (Equation 2) and (Equation 3), it can be understood that when the average pixel value AveRGB is equal to or less than the threshold value Tp, the power consumption PWa of the LED display device 1 is equal to or less than the power saving control target value PWt. .. 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 power saving control is performed. It can be understood 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 brightness of the plurality of LEDs provided in the display unit 16 is lowered to reduce the power consumption PWa of the LED display device 1 as a power saving control target. Includes processing to make the value PWt or less. As a result, the brightness correction control circuit 14 can always set the power consumption PWa of the LED display device 1 to the power saving control target value PWt or less.
　図８は、実施の形態１のＬＥＤ表示装置が演算した平均画素値AveRGBと当該ＬＥＤ表示装置が演算した第１の輝度補正係数との関係を図示するグラフである。 FIG. 8 is a graph illustrating the relationship between the average pixel value AveRGB calculated by the LED display device of the first embodiment and the first luminance correction coefficient calculated by the LED display device.
　ステップＳ５，Ｓ６及びＳ７が実行されることにより、図８に図示されるように、第１の輝度補正係数は、平均画素値AveRGBが閾値Tp以下である場合は１になり、平均画素値AveRGBが閾値Tpより大きい場合は１より小さくなる。 By executing steps S5, S6 and S7, as shown in FIG. 8, the first luminance correction coefficient becomes 1 when the average pixel value AveRGB is equal to or less than the threshold value Tp, and the average pixel value AveRGB becomes. Is less than 1 when is greater than the threshold Tp.
　第１の輝度補正係数演算回路３３ａは、図８に図示されるように、平均画素値AveRGBが閾値Tpより大きい場合は、平均画素値AveRGBが大きくなるほど第１の輝度補正係数が小さくなるように、第１の輝度補正係数を演算する。このため、図８に図示されるように、第１の輝度補正係数は、平均画素値AveRGBが閾値Tpから最大画素値255に近づくにつれて小さくなる。 As shown in FIG. 8, in the first luminance correction coefficient calculation circuit 33a, when the average pixel value AveRGB is larger than the threshold value Tp, the first luminance correction coefficient becomes smaller as the average pixel value AveRGB becomes larger. , Calculate the first luminance correction coefficient. Therefore, as shown in FIG. 8, the first luminance correction coefficient becomes smaller as the average pixel value AveRGB approaches the maximum pixel value 255 from the threshold value Tp.
　また、第１の輝度補正係数演算回路３３ａは、図８に図示されるように、平均画素値AveRGBが閾値Tpより大きい場合は、補正された映像信号５０に含まれる複数の画素値５１の平均を示す平均画素値が閾値Tpとなるように第１の輝度補正係数を演算する。このような第１の輝度補正係数の演算は、第１の輝度補正係数演算回路３３ａが、メモリ等に格納されていた計算式、テーブル等を読み出し、読み出した計算式、テーブル等を用いて演算を実行することにより、実行することができる。 Further, as shown in FIG. 8, the first luminance correction coefficient calculation circuit 33a averages a plurality of pixel values 51 included in the corrected video signal 50 when the average pixel value AveRGB is larger than the threshold value Tp. The first luminance correction coefficient is calculated so that the average pixel value indicating is the threshold value Tp. In such a calculation of the first luminance correction coefficient, the first luminance correction coefficient calculation circuit 33a reads out a calculation formula, a table, etc. stored in a memory or the like, and calculates using the read calculation formula, the table, etc. It can be executed by executing.
　例えば、第１の輝度補正係数Mulaは、（式４）により演算することができる。 For example, the first luminance correction coefficient Mula can be calculated by (Equation 4).
Figure JPOXMLDOC01-appb-M000004
Figure JPOXMLDOC01-appb-M000004
　ステップＳ８においては、駆動電流値選択回路３２が、演算された輝度情報４２が駆動電流値４５ｓの選択のための閾値４６以上であるか否かを判定する。実施の形態１においては、駆動電流値選択回路３２は、閾値Tcを駆動電流値４５ｓの選択のための閾値４６として用い、平均画素値AveRGBが閾値Tc以上であるか否かを判定する。平均画素値AveRGBが閾値Tcより小さいと判定された場合は、ステップＳ９及びＳ１０が実行された後にステップＳ１４が実行される。平均画素値AveRGBが閾値Tc以上であると判定された場合は、ステップＳ１１，Ｓ１２及びＳ１３が実行された後にステップＳ１４が実行される。 In step S8, the drive current value selection circuit 32 determines whether or not the calculated luminance information 42 is equal to or greater than the threshold value 46 for selecting the drive current value 45s. In the first embodiment, the drive current value selection circuit 32 uses the threshold value Tc as the threshold value 46 for selecting the drive current value 45s, and determines whether or not the average pixel value AveRGB is equal to or greater than the threshold value Tc. If it is determined that the average pixel value AveRGB is smaller than the threshold value Tc, step S14 is executed after steps S9 and S10 are executed. If it is determined that the average pixel value AveRGB is equal to or greater than the threshold value Tc, step S14 is executed after steps S11, S12, and S13 are executed.
　ステップＳ９においては、駆動電流値選択回路３２が、設定されている２種類の駆動電流値から第１の駆動電流値IRa,IGa及びIBaを選択する。選択される第１の駆動電流値IRa,IGa及びIBaは、ＬＥＤ表示装置１の消費電力が抑制されない場合に使用される、初期の駆動電流値である。選択された第１の駆動電流値IRa,IGa及びIBaは、補正演算回路３４及び駆動回路１５に入力される。 In step S9, the drive current value selection circuit 32 selects the first drive current values IRa, IGa and IBa from the two types of set drive current values. The first drive current values IRa, IGa and IBa selected are the initial drive current values used when the power consumption of the LED display device 1 is not suppressed. The selected first drive current values IRa, IGa and IBa are input to the correction calculation circuit 34 and the drive circuit 15.
　続くステップＳ１０においては、補正演算回路３４が、第１の駆動電流値IRa,IGa及びIBaに対応する第１の輝度補正係数により映像信号４１を補正する。実施の形態１においては、補正演算回路３４は、映像信号４１に含まれる複数の画素値４３に第１の輝度補正係数を乗算することにより、映像信号４１を補正する。補正された映像信号５０は、駆動回路１５に入力される。 In the following step S10, the correction calculation circuit 34 corrects the video signal 41 with the first luminance correction coefficient corresponding to the first drive current values IRa, IGa and IBa. In the first embodiment, the correction calculation circuit 34 corrects the video signal 41 by multiplying the plurality of pixel values 43 included in the video signal 41 by the first luminance correction coefficient. The corrected video signal 50 is input to the drive circuit 15.
　ステップＳ１１においては、駆動電流値選択回路３２が、設定されている２種類の駆動電流値から第２の駆動電流値IRb,IGb及びIBbを選択する。選択される第２の駆動電流値IRb,IGb及びIBbは、ＬＥＤ表示装置１の消費電力が抑制される場合に使用される、初期の駆動電流値より小さい追加の駆動電流値である。選択された第２の駆動電流値IRb,IGb及びIBbは、補正演算回路３４及び駆動回路１５に入力される。 In step S11, the drive current value selection circuit 32 selects the second drive current values IRb, IGb, and IBb from the two types of set drive current values. The second drive current values IRb, IGb and IBb selected are additional drive current values smaller than the initial drive current value used when the power consumption of the LED display device 1 is suppressed. The selected second drive current values IRb, IGb and IBb are input to the correction calculation circuit 34 and the drive circuit 15.
　続くステップＳ１２においては、第２の輝度補正係数演算回路３３ｂが、第２の輝度補正係数を演算して、表示部１６に備えられる複数のＬＥＤの輝度を低くする値を第２の輝度補正係数に割り当てる。実施の形態１においては、第２の輝度補正係数演算回路３３ｂは、第２の輝度補正係数に１より小さい値を割り当てる。映像信号４１が第２の輝度補正係数により補正される場合は、映像信号４１に含まる複数の画素値４３に第２の輝度補正係数が乗算される。このため、第２の輝度補正係数に１より小さい値が割り当てられた場合は、映像信号４１が第２の輝度補正係数により補正された場合の当該複数のＬＥＤの輝度は、映像信号４１が補正されなかった場合のそれより低い。すなわち、映像信号４１が第２の輝度補正係数により補正された場合の表示部１６に表示される映像の輝度は、映像信号４１が補正されなかった場合のそれより低い。 In the following step S12, the second luminance correction coefficient calculation circuit 33b calculates the second luminance correction coefficient, and sets the value for lowering the brightness of the plurality of LEDs provided in the display unit 16 as the second luminance correction coefficient. Assign to. In the first embodiment, the second luminance correction coefficient calculation circuit 33b assigns a value smaller than 1 to the second luminance correction coefficient. When the video signal 41 is corrected by the second luminance correction coefficient, the second luminance correction coefficient is multiplied by the plurality of pixel values 43 included in the video signal 41. Therefore, when a value smaller than 1 is assigned to the second brightness correction coefficient, the video signal 41 corrects the brightness of the plurality of LEDs when the video signal 41 is corrected by the second brightness correction coefficient. Lower than that if not done. That is, the brightness of the video displayed on the display unit 16 when the video signal 41 is corrected by the second brightness correction coefficient is lower than that when the video signal 41 is not corrected.
　続くステップＳ１３においては、補正演算回路３４が、第２の輝度補正係数により映像信号４１を補正する。実施の形態１においては、補正演算回路３４は、映像信号４１に含まれる複数の画素値４３に第２の輝度補正係数を乗算することにより、第２の輝度補正係数により映像信号４１を補正する。補正された映像信号５０は、駆動回路１５に入力される。 In the following step S13, the correction calculation circuit 34 corrects the video signal 41 with the second luminance correction coefficient. In the first embodiment, the correction calculation circuit 34 corrects the video signal 41 by the second luminance correction coefficient by multiplying the plurality of pixel values 43 included in the video signal 41 by the second luminance correction coefficient. .. The corrected video signal 50 is input to the drive circuit 15.
　図９は、実施の形態１のＬＥＤ表示装置が演算した平均画素値AveRGBと当該ＬＥＤ表示装置が演算した第２の輝度補正係数との関係を図示するグラフである。 FIG. 9 is a graph illustrating 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.
　ステップＳ８及びＳ１２が実行されることにより、図９に図示されるように、第２の輝度補正係数は、平均画素値AveRGBが閾値Tcより大きい場合は１より小さくなる。 By executing steps S8 and S12, as shown in FIG. 9, the second luminance correction coefficient becomes smaller than 1 when the average pixel value AveRGB is larger than the threshold value Tc.
　また、図８及び図９に図示されるように、平均画素値AveRGBが閾値Tc以上である場合は、映像信号４１が第２の輝度補正係数により補正されたときの表示部１６に備えられる複数のＬＥＤのオン期間における輝度は、映像信号４１が第１の輝度補正係数により補正されたときの当該複数のＬＥＤのオン期間における輝度より高い。 Further, as shown in FIGS. 8 and 9, when the average pixel value AveRGB is equal to or higher than the threshold value Tc, a plurality of display units 16 provided when the video signal 41 is corrected by the second luminance correction coefficient. The brightness of the LED in the ON period is higher than the brightness of the plurality of LEDs in the ON period when the video signal 41 is corrected by the first luminance correction coefficient.
　第２の輝度補正係数演算回路３３ｂは、図９に図示されるように、平均画素値AveRGBが閾値Tc以上である場合は平均画素値AveRGBが大きくなるほど第２の輝度補正係数が小さくなるように、第２の輝度補正係数を演算する。このため、図９に図示されるように、第２の輝度補正係数は、平均画素値AveRGBが閾値Tcから最大画素値255に近づくにつれて小さくなる。 As shown in FIG. 9, the second luminance correction coefficient calculation circuit 33b is such that when the average pixel value AveRGB is equal to or greater than the threshold value Tc, the second luminance correction coefficient becomes smaller as the average pixel value AveRGB becomes larger. , The second luminance correction coefficient is calculated. Therefore, as shown in FIG. 9, the second luminance correction coefficient becomes smaller as the average pixel value AveRGB approaches the maximum pixel value 255 from the threshold value Tc.
　また、第２の輝度補正係数演算回路３３ｂは、補正された映像信号５０に含まれる複数の画素値４３の平均を示す平均画素値が閾値Tcとなるように第２の輝度補正係数を演算する。このような第２の輝度補正係数の演算は、第２の輝度補正係数演算回路３３ｂが、メモリ等に格納されていた計算式、テーブル等を読み出し、読み出した計算式、テーブル等を用いて演算を実行することにより、実行することができる。 Further, the second luminance correction coefficient calculation circuit 33b calculates the second luminance correction coefficient so that the average pixel value indicating the average of the plurality of pixel values 43 included in the corrected video signal 50 becomes the threshold value Tc. .. In such a calculation of the second luminance correction coefficient, the second luminance correction coefficient calculation circuit 33b reads out a calculation formula, a table, etc. stored in a memory or the like, and calculates using the read calculation formula, the table, etc. It can be executed by executing.
　第１の輝度補正係数演算回路３３ａは、平均画素値AveRGBが閾値Tpより大きく閾値Tcより小さい場合は、第１の輝度補正係数に１より小さい値を割り当てる。また、第２の輝度補正係数演算回路３３ｂは、平均画素値AveRGBが閾値Tc以上である場合は、第２の輝度補正係数に１より小さい値を割り当てる。このため、輝度補正係数演算回路３３は、平均画素値AveRGBが閾値Tpより大きい場合は、第１の輝度補正係数及び第２の輝度補正係数の各々により映像信号４１が補正されたときの表示部１６に備えられる複数のＬＥＤのオン期間における輝度が、映像信号４１が補正されないときのそれより小さくなるように、第１の輝度補正係数及び第２の輝度補正係数を演算する。 The first luminance correction coefficient calculation circuit 33a assigns a value smaller than 1 to the first luminance correction coefficient when the average pixel value AveRGB is larger than the threshold value Tp and smaller than the threshold value Tc. Further, the second luminance correction coefficient calculation circuit 33b assigns a value smaller than 1 to the second luminance correction coefficient when the average pixel value AveRGB is equal to or more than the threshold value Tc. Therefore, when the average pixel value AveRGB is larger than the threshold value Tp, the luminance correction coefficient calculation circuit 33 is a display unit when the video signal 41 is corrected by each of the first luminance correction coefficient and the second luminance correction coefficient. The first luminance correction coefficient and the second luminance correction coefficient are calculated so that the luminance of the plurality of LEDs provided in 16 during the on period is smaller than that when the video signal 41 is not corrected.
　例えば、第２の輝度補正係数Mulbは、（式５）により演算することができる。 For example, the second luminance correction coefficient Mulb can be calculated by (Equation 5).
Figure JPOXMLDOC01-appb-M000005
Figure JPOXMLDOC01-appb-M000005
　ここで、閾値Tcを演算する方法を説明する。 Here, the method of calculating the threshold value Tc will be described.
　閾値Tcが演算される際には、まず、表示部１６に備えられる複数のＬＥＤに第１の駆動電流値IRa,IGa及びIBa、及び最大画素値255に応じたデューティー比を有する駆動電流が供給されて当該複数のＬＥＤが全点灯させられ、当該複数のＬＥＤの輝度YRa,YGa及びYBaが図示されない測定器により測定される。また、当該複数のＬＥＤに第２の駆動電流値IRb,IGb及びIBb、及び最大画素値255に応じたデューティー比を有する駆動電流が供給されて当該複数のＬＥＤが全点灯させられ、当該複数のＬＥＤの輝度YRb,YGb及びYBbが図示されない測定器により測定される。 When the threshold value Tc is calculated, first, a drive current having a duty ratio corresponding to the first drive current values IRa, IGa and IBa, and the maximum pixel value 255 is supplied to a plurality of LEDs provided in the display unit 16. Then, the plurality of LEDs are all turned on, and the brightness YRa, YGa and YBa of the plurality of LEDs are measured by a measuring instrument (not shown). Further, a drive current having a duty ratio corresponding to the second drive current values IRb, IGb and IBb and the maximum pixel value 255 is supplied to the plurality of LEDs to fully turn on the plurality of LEDs, and the plurality of LEDs are all lit. The brightness of the LEDs YRb, YGb and YBb is measured by a measuring instrument (not shown).
　平均画素値AveRGBが閾値Tpである場合の表示部１６に備えられる複数のＬＥＤの輝度YRTa,YGTa及びYBTaは、測定された輝度YRa,YGa及びYBa、並びに閾値Tpを用いて、（式６）により表される。 The brightness YRTa, YGTa and YBTa of the plurality of LEDs provided in the display unit 16 when the average pixel value AveRGB is the threshold value Tp are determined by using the measured brightness YRa, YGa and YBa and the threshold value Tp (Equation 6). Represented by.
Figure JPOXMLDOC01-appb-M000006
Figure JPOXMLDOC01-appb-M000006
　閾値Tcは、（式７）を満たすように設定される。 The threshold value Tc is set so as to satisfy (Equation 7).
Figure JPOXMLDOC01-appb-M000007
Figure JPOXMLDOC01-appb-M000007
　閾値Tcが（式７）を満たすように設定された場合は、映像信号４１が第１の輝度補正係数により補正され第１の駆動電流値IRa,IGa及びIBaで表示部１６に備えられる複数のＬＥＤが駆動された場合の当該複数のＬＥＤの輝度と、映像信号４１が第２の輝度補正係数により補正され第２の駆動電流値IRb,IGb及びIBbで当該複数のＬＥＤが駆動された場合の当該複数のＬＥＤの輝度と、が、平均画素値AveRGBが閾値Tcである場合に一致する。このため、駆動電流値４５ｓが第１の駆動電流値IRa,IGa及びIBaと第２の駆動電流値IRb,IGb及びIBbとの間で切り替えられた際に、当該複数のＬＥＤの輝度が不連続的に変化しない。 When the threshold value Tc is set to satisfy (Equation 7), the video signal 41 is corrected by the first luminance correction coefficient, and a plurality of display units 16 are provided with the first drive current values IRa, IGa, and IBa. When the brightness of the plurality of LEDs when the LEDs are driven and the video signal 41 are corrected by the second brightness correction coefficient and the plurality of LEDs are driven by the second drive current values IRb, IGb and IBb. The brightness of the plurality of LEDs matches when the average pixel value AveRGB is the threshold Tc. Therefore, when the drive current value 45s is switched between the first drive current values IRa, IGa and IBa and the second drive current values IRb, IGb and IBb, the brightness of the plurality of LEDs is discontinuous. Does not change.
　第１の駆動電流値IRa,IGa及びIBa、並びに第２の駆動電流値IRb,IGb及びIBbは、(IRb,IGb,IBb)<(IRa,IGa,IBa)という関係を満たす。このため、輝度YRa,YGa及びYBa、並びに輝度YRb,YGb及びYBbは、(YRa,YGa,YBa)<(YRa,YGa,YBa)という関係を満たす。したがって、閾値Tp及びTcは、Tp<Tcという関係を満たす。 The first drive current values IRa, IGa and IBa, and the second drive current values IRb, IGb and IBb satisfy the relationship (IRb, IGb, IBb) <(IRa, IGa, IBa). Therefore, the luminance YRa, YGa and YBa, and the luminance YRb, YGb and YBb satisfy the relationship (YRa, YGa, YBa) <(YRa, YGa, YBa). Therefore, the thresholds Tp and Tc satisfy the relationship Tp <Tc.
　表示部１６に備えられる複数のＬＥＤに第２の駆動電流値IRb,IGb及びIBb、及び最大画素値255に応じたデューティー比を有する駆動電流が供給されて当該複数のＬＥＤが全点灯させられた場合のＬＥＤ表示装置１の消費電力をPWballとした場合は、当該複数のＬＥＤに第２の駆動電流値IRb,IGb及びIBb、及び閾値Tcに一致する平均画素値AveRGBに応じたデューティー比を有する駆動電流が供給されて当該複数のＬＥＤが全点灯させられた場合のＬＥＤ表示装置１の消費電力PWbは、（式８）により表される。 A drive current having a duty ratio corresponding to the second drive current values IRb, IGb and IBb, and the maximum pixel value 255 was supplied to the plurality of LEDs provided in the display unit 16, and the plurality of LEDs were all lit. When the power consumption of the LED display device 1 in this case is PWball, the plurality of LEDs have a duty ratio corresponding to the second drive current values IRb, IGb and IBb, and the average pixel value AveRGB corresponding to the threshold Tc. The power consumption PWb of the LED display device 1 when the drive current is supplied and the plurality of LEDs are all lit is represented by (Equation 8).
Figure JPOXMLDOC01-appb-M000008
Figure JPOXMLDOC01-appb-M000008
　また、上述したように、ＬＥＤの発光効率は、駆動電流値４５ｓが最大駆動電流値に近づくにつれて低くなる。このため、消費電力PWb及びPWtは、PWb<PWtという関係を満たす。 Further, as described above, the luminous efficiency of the LED decreases as the drive current value 45s approaches the maximum drive current value. Therefore, the power consumptions PWb and PWt satisfy the relationship of PWb <PWt.
　ステップＳ１４においては、駆動回路１５が、入力された映像信号４１にしたがって、入力された駆動電流値４５ｓで表示部１６に備えられる複数のＬＥＤを駆動する。これにより、表示部１６には、補正された映像信号５０に応じた映像が表示される。表示される映像は、駆動電流値４５ｓに応じた輝度を有する。 In step S14, the drive circuit 15 drives a plurality of LEDs provided in the display unit 16 with the input drive current value 45s according to the input video signal 41. As a result, the display unit 16 displays the image corresponding to the corrected image signal 50. The displayed image has a brightness corresponding to the drive current value of 45 s.
　１．７　実施の形態１の発明の効果
　実施の形態１の発明によれば、輝度情報４２に基づいて選択される駆動電流値４５ｓで表示部１６に備えられる複数のＬＥＤが駆動される。このため、当該複数のＬＥＤの発光効率が高くなる駆動電流値４５ｓで当該複数のＬＥＤを駆動することができる。 1.7 Effect of the Invention of the First Embodiment According to the invention of the first embodiment, a plurality of LEDs provided in the display unit 16 are driven by a drive current value 45s selected based on the luminance information 42. Therefore, the plurality of LEDs can be driven with a drive current value of 45 s that increases the luminous efficiency of the plurality of LEDs.
　また、実施の形態１の発明によれば、選択される駆動電流値４５ｓに応じた輝度補正係数４７ｓにより映像信号４１が補正される。このため、表示部１６に備えられる複数のＬＥＤの発光効率が高くなる駆動電流値４５ｓで当該複数のＬＥＤを駆動しながら、当該複数のＬＥＤの輝度に関連するＬＥＤ表示装置１の画質の劣化を抑制することができる。 Further, according to the invention of the first embodiment, the video signal 41 is corrected by the luminance correction coefficient 47s according to the selected drive current value 45s. Therefore, while driving the plurality of LEDs with a drive current value of 45 s that increases the luminous efficiency of the plurality of LEDs provided in the display unit 16, the deterioration of the image quality of the LED display device 1 related to the brightness of the plurality of LEDs is deteriorated. It can be suppressed.
　これらにより、ＬＥＤ表示装置１の消費電力を抑制しながら、ＬＥＤ表示装置１の画質の劣化を抑制することができる。 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.
　さらに、実施の形態１の発明によれば、平均画素値AveRGBが閾値Tp以下である場合はＬＥＤ表示装置１の消費電力PWaが省電力制御目標値PWt以下となるように閾値Tpが設定される。また、平均画素値AveRGBが閾値Tpより大きい場合は、１より小さい値が割り当てられた第１の輝度補正係数又は第２の輝度補正係数により映像信号４１が補正されて表示部１６に備えられる複数のＬＥＤの輝度が低くされる。このため、ＬＥＤ表示装置１の消費電力PWaを省電力制御目標値PWt以下にすることができる。 Further, according to the invention of the first embodiment, when the average pixel value AveRGB is equal to or less than the threshold value Tp, the threshold value Tp is set so that the power consumption PWa of the LED display device 1 is equal to or less than the power saving control target value PWt. .. When the average pixel value AveRGB is larger than the threshold value Tp, the video signal 41 is corrected by the first luminance correction coefficient or the second luminance correction coefficient to which a value smaller than 1 is assigned, and a plurality of the display unit 16 is provided. The brightness of the LED is lowered. Therefore, the power consumption PWa of the LED display device 1 can be set to the power saving control target value PWt or less.
　さらに、実施の形態１の発明によれば、映像信号４１が第１の輝度補正係数により補正され第１の駆動電流値IRa,IGa及びIBaで表示部１６に備えられる複数のＬＥＤが駆動された場合の当該複数のＬＥＤの輝度と、映像信号４１が第２の輝度補正係数により補正され第２の駆動電流値IRb,IGb及びIBbで当該複数のＬＥＤが駆動された場合の複数のＬＥＤの輝度と、が、平均画素値AveRGBが閾値Tcである場合に一致する。このため、駆動電流値４５ｓが第１の駆動電流値IRa,IGa及びIBaと第２の駆動電流値IRb,IGb及びIBbとの間で切り替えられた際に、当該複数のＬＥＤの輝度が不連続的に変化しない。 Further, according to the invention of the first embodiment, the video signal 41 is corrected by the first luminance correction coefficient, and a plurality of LEDs provided in the display unit 16 are driven by the first drive current values IRa, IGa and IBa. The brightness of the plurality of LEDs in the case and the brightness of the plurality of LEDs when the video signal 41 is corrected by the second brightness correction coefficient and the plurality of LEDs are driven by the second drive current values IRb, IGb and IBb. And, match when the average pixel value AveRGB is the threshold Tc. Therefore, when the drive current value 45s is switched between the first drive current values IRa, IGa and IBa and the second drive current values IRb, IGb and IBb, the brightness of the plurality of LEDs is discontinuous. Does not change.
　さらに、実施の形態１の発明によれば、平均画素値AveRGBが閾値Tc以上である場合は、駆動電流値４５ｓが、初期の駆動電流値である第１の駆動電流値から、初期の駆動電流値より小さい追加の駆動電流値である第２の駆動電流値に切り替えられる。これにより、駆動電流値４５ｓが、ＬＥＤの発光効率が低下する最大駆動電流値に近づくことを抑制することができ、ＬＥＤ表示装置１の消費電力を抑制することができる。 Further, according to the invention of the first embodiment, when the average pixel value AveRGB is equal to or higher than the threshold value Tc, the drive current value 45s is the initial drive current from the first drive current value which is the initial drive current value. It is switched to a second drive current value, which is an additional drive current value smaller than the value. As a result, it is possible to prevent the drive current value 45s from approaching the maximum drive current value at which the luminous efficiency of the LED is lowered, and it is possible to suppress the power consumption of the LED display device 1.
　さらに、実施の形態１の発明によれば、平均画素値AveRGBが閾値Tc以上となった場合に、駆動電流値４５ｓが第１の駆動電流値からそれより小さい第２の駆動電流値に変更され、輝度補正係数４７ｓが第１の輝度補正係数からそれより大きい第２の輝度補正係数に変更される。これにより、ＬＥＤ表示装置１の消費電力を抑制しながら、表示部１６に表示される映像のダイナミックレンジが縮小されることを抑制することができる。例えば、駆動電流値４５ｓの変更が行われ、輝度補正係数４７ｓの変更が行われ、閾値Tpが128であり、閾値Tcが190であり、平均画素値AveRGBが200である場合は、映像信号４１に含まれる最大画素値255が補正された映像信号５０に含まれる画素値242に変換されるとする。この場合は、映像信号４１が255階調を有し、補正された映像信号５０が243階調を有する。しかし、駆動電流値４５ｓの変更が行われず輝度補正係数４７ｓの変更のみが行われた場合は、補正された映像信号５０は164階調しか有しない。したがって、駆動電流値４５ｓの変更が行われず輝度補正係数４７ｓの変更のみが行われた場合は、駆動電流値４５ｓの変更が行われ輝度補正係数４７ｓの変更が行われた場合と比較して、表示部１６に表示される映像のダイナミックレンジが縮小され、出力階調のつぶれ等の視覚的な問題が生じる。 Further, according to the invention of the first embodiment, when the average pixel value AveRGB becomes equal to or higher than the threshold value Tc, the drive current value 45s is changed from the first drive current value to a second drive current value smaller than that. , The brightness correction coefficient 47s is changed from the first brightness correction coefficient to a second brightness correction coefficient larger than that. As a result, it is possible to suppress the reduction of the dynamic range of the image displayed on the display unit 16 while suppressing the power consumption of the LED display device 1. For example, when the drive current value 45s is changed, the brightness correction coefficient 47s is changed, the threshold value Tp is 128, the threshold value Tc is 190, and the average pixel value AveRGB is 200, the video signal 41 It is assumed that the maximum pixel value 255 included in is converted to the pixel value 242 included in the corrected video signal 50. In this case, the video signal 41 has 255 gradations, and the corrected video signal 50 has 243 gradations. However, when the drive current value 45s is not changed and only the luminance correction coefficient 47s is changed, the corrected video signal 50 has only 164 gradations. Therefore, when the drive current value 45s is not changed and only the brightness correction coefficient 47s is changed, the drive current value 45s is changed and the brightness correction coefficient 47s is changed as compared with the case where the brightness correction coefficient 47s is changed. The dynamic range of the image displayed on the display unit 16 is reduced, causing visual problems such as crushed output gradation.
　なお、本発明は、その発明の範囲内において、実施の形態を適宜、変形、省略することが可能である。 In the present invention, the embodiments can be appropriately modified or omitted within the scope of the invention.
　この発明は詳細に説明されたが、上記した説明は、すべての局面において、例示であって、この発明がそれに限定されるものではない。例示されていない無数の変形例が、この発明の範囲から外れることなく想定され得るものと解される。 Although the present invention has been described in detail, the above description is an example in all aspects, and the present 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　ＬＥＤ表示装置、１３　省電力制御目標値入力部、１５　駆動回路、１６　表示部、３１　輝度情報演算回路、３２　駆動電流値選択回路、３３　輝度補正係数演算回路、３４　補正演算回路、４１　映像信号、４２　輝度情報、４３　複数の画素値、４４　総和又は平均、４５　ｎ種類の駆動電流値、４５ｓ　駆動電流値、４６　駆動電流値の選択のための閾値、４７　ｎ種類の輝度補正係数、４７ｓ　輝度補正係数、４８　省電力制御目標値、４９　ｎ種類の輝度補正係数の演算のための閾値、５０　補正された映像信号、５２　駆動信号、５３　デューティー比。 1 LED display device, 13 power saving control target value input unit, 15 drive circuit, 16 display unit, 31 brightness information calculation circuit, 32 drive current value selection circuit, 33 brightness correction coefficient calculation circuit, 34 correction calculation circuit, 41 video signal , 42 luminance information, 43 multiple pixel values, 44 total or average, 45 n types of drive current value, 45 s drive current value, 46 threshold for selecting drive current value, 47 n types of brightness correction coefficient, 47 s brightness Correction coefficient, 48 power saving control target value, 49 thresholds for calculating n types of luminance correction coefficients, 50 corrected video signal, 52 drive signal, 53 duty ratio.

Claims (9)

  1. 　映像信号から輝度情報を演算する輝度情報演算部と、
    　ｎを２以上の整数として前記輝度情報に基づいてｎ種類の駆動電流値から駆動電流値を選択する駆動電流値選択部と、
    　前記輝度情報に基づいて前記ｎ種類の駆動電流値にそれぞれ対応するｎ種類の輝度補正係数を演算する輝度補正係数演算部と、
    　前記駆動電流値に対応する輝度補正係数により前記映像信号を補正して補正された映像信号を得る補正演算部と、
    　複数のＬＥＤを備える表示部と、
    　前記補正された映像信号にしたがって前記駆動電流値で前記複数のＬＥＤを駆動する駆動回路と、
    を備えるＬＥＤ表示装置。     A luminance information calculation unit that calculates luminance information from a video signal,
    A drive current value selection unit that selects a drive current value from n types of drive current values based on the luminance information, where n is an integer of 2 or more.
    A luminance correction coefficient calculation unit that calculates n types of luminance correction coefficients corresponding to the n types of drive current values based on the luminance information, and a luminance correction coefficient calculation unit.
    A correction calculation unit that corrects the video signal with a luminance correction coefficient corresponding to the drive current value and obtains the corrected video signal.
    A display unit with multiple LEDs and
    A drive circuit that drives the plurality of LEDs with the drive current value according to the corrected video signal, and
    An LED display device comprising.
  2. 　前記輝度補正係数演算部は、前記輝度情報が前記ｎ種類の輝度補正係数の演算のための閾値より大きい場合は、前記ｎ種類の輝度補正係数の各々により前記映像信号が補正されたときの前記複数のＬＥＤのオン期間における輝度が、前記映像信号が補正されないときの前記複数のＬＥＤのオン期間における輝度より小さくなるように、前記ｎ種類の輝度補正係数を演算する
    請求項１のＬＥＤ表示装置。     When the luminance information is larger than the threshold value for calculating the n kinds of luminance correction coefficients, the luminance correction coefficient calculation unit said that when the video signal is corrected by each of the n kinds of luminance correction coefficients. The LED display device according to claim 1, which calculates the n kinds of luminance correction coefficients so that the luminance in the on-period of the plurality of LEDs is smaller than the luminance in the on-period of the plurality of LEDs when the video signal is not corrected. ..
  3. 　前記ＬＥＤ表示装置の消費電力の上限が入力される入力部をさらに備え、
    　前記輝度補正係数演算部は、前記上限に基づいて前記ｎ種類の輝度補正係数の演算のための閾値を設定する
    請求項２のＬＥＤ表示装置。     An input unit for inputting an upper limit of the power consumption of the LED display device is further provided.
    The LED display device according to claim 2, wherein the luminance correction coefficient calculation unit sets a threshold value for calculating the n types of luminance correction coefficients based on the upper limit.
  4. 　前記駆動電流値選択部は、前記輝度情報と前記駆動電流値の選択のための閾値との大小関係に基づいて前記駆動電流値を選択する
    請求項１から３までのいずれかのＬＥＤ表示装置。     The LED display device according to any one of claims 1 to 3, wherein the drive current value selection unit selects the drive current value based on the magnitude relationship between the luminance information and the threshold value for selecting the drive current value.
  5. 　前記ｎ種類の駆動電流値は、第１の駆動電流値、及び前記第１の駆動電流値より小さい第２の駆動電流値を含み、
    　前記ｎ種類の輝度補正係数は、前記第１の駆動電流値及び前記第２の駆動電流値にそれぞれ対応する第１の輝度補正係数及び第２の輝度補正係数を含み、
    　前記駆動電流値選択部は、前記輝度情報が前記駆動電流値の選択のための閾値より小さい場合は、前記第１の駆動電流値を前記駆動電流値として選択し、前記輝度情報が前記駆動電流値の選択のための閾値以上である場合は、前記第２の駆動電流値を前記駆動電流値として選択し、
    　前記輝度補正係数演算部は、前記輝度情報が前記駆動電流値の選択のための閾値以上である場合は、前記映像信号が前記第２の輝度補正係数により補正された場合の前記複数のＬＥＤのオン期間における輝度が、前記映像信号が前記第１の輝度補正係数により補正されたときの前記複数のＬＥＤのオン期間における輝度より高くなるように、前記第１の輝度補正係数及び前記第２の輝度補正係数を演算する
    請求項１から４までのいずれかのＬＥＤ表示装置。     The n types of drive current values include a first drive current value and a second drive current value smaller than the first drive current value.
    The n types of brightness correction coefficients include a first brightness correction coefficient and a second brightness correction coefficient corresponding to the first drive current value and the second drive current value, respectively.
    When the brightness information is smaller than the threshold value for selecting the drive current value, the drive current value selection unit selects the first drive current value as the drive current value, and the brightness information is the drive current. When it is equal to or more than the threshold value for selecting a value, the second drive current value is selected as the drive current value, and the value is selected.
    When the luminance information is equal to or greater than the threshold value for selecting the drive current value, the luminance correction coefficient calculation unit of the plurality of LEDs when the video signal is corrected by the second luminance correction coefficient. The first luminance correction coefficient and the second luminance correction coefficient so that the luminance in the on-period is higher than the luminance in the on-period of the plurality of LEDs when the video signal is corrected by the first luminance correction coefficient. The LED display device according to any one of claims 1 to 4 for calculating a luminance correction coefficient.
  6. 　前記駆動電流値の選択のための閾値は、前記映像信号が前記第１の輝度補正係数により補正され前記複数のＬＥＤが前記第１の駆動電流値で駆動された場合の前記複数のＬＥＤの輝度と、前記映像信号が前記第２の輝度補正係数により補正され前記複数のＬＥＤが前記第２の駆動電流値で駆動された場合の前記複数のＬＥＤの輝度と、が、前記輝度情報が前記駆動電流値の選択のための閾値である場合に一致するように、設定される
    請求項５のＬＥＤ表示装置。     The threshold value for selecting the drive current value is the brightness of the plurality of LEDs when the video signal is corrected by the first brightness correction coefficient and the plurality of LEDs are driven by the first drive current value. When the video signal is corrected by the second luminance correction coefficient and the plurality of LEDs are driven by the second driving current value, the luminance information of the plurality of LEDs is driven by the luminance information. The LED display device according to claim 5, which is set so as to match the case where it is a threshold value for selecting a current value.
  7. 　前記輝度補正係数演算部は、前記輝度情報が前記ｎ種類の輝度補正係数の演算のための閾値より大きい場合は、前記映像信号が前記第１の輝度補正係数及び前記第２の輝度補正係数の各々により補正されたときの前記複数のＬＥＤのオン期間における輝度が、前記映像信号が補正されないときの前記複数のＬＥＤのオン期間における輝度より小さくなるように、前記第１の輝度補正係数及び前記第２の輝度補正係数を演算する
    請求項５又は６のＬＥＤ表示装置。     In the luminance correction coefficient calculation unit, when the luminance information is larger than the threshold value for calculating the n kinds of luminance correction coefficients, the video signal is the first luminance correction coefficient and the second luminance correction coefficient. The first luminance correction coefficient and the said, so that the luminance in the on-period of the plurality of LEDs when corrected by each is smaller than the luminance in the on-period of the plurality of LEDs when the video signal is not corrected. The LED display device according to claim 5 or 6, which calculates a second luminance correction coefficient.
  8. 　前記映像信号は、前記複数のＬＥＤの輝度をそれぞれ示す複数の画素値を含み、
    　前記輝度情報は、前記複数の画素値の総和又は平均を含み、
    　前記補正演算部は、前記複数の画素値に前記輝度補正係数を乗算することにより、前記映像信号を補正する
    請求項１から７までのいずれかのＬＥＤ表示装置。     The video signal includes a plurality of pixel values indicating the brightness of the plurality of LEDs, respectively.
    The luminance information includes the sum or average of the plurality of pixel values.
    The LED display device according to any one of claims 1 to 7, wherein the correction calculation unit corrects the video signal by multiplying the plurality of pixel values by the brightness correction coefficient.
  9. 　前記駆動回路は、前記補正された映像信号に応じたデューティー比を有する駆動信号を前記複数のＬＥＤに供給することにより、前記補正された映像信号にしたがって前記複数のＬＥＤを駆動する
    請求項１から８までのいずれかのＬＥＤ表示装置。     According to claim 1, the drive circuit supplies the plurality of LEDs with a drive signal having a duty ratio corresponding to the corrected video signal, thereby driving the plurality of LEDs according to the corrected video signal. Any LED display device up to 8.
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