WO2021038794A1 - Dispositif d'affichage à del - Google Patents

Dispositif d'affichage à del 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
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PCT/JP2019/033911
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English (en)
Japanese (ja)
Inventor
隆志 的場
浅村　吉範
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三菱電機株式会社
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Priority to PCT/JP2019/033911 priority Critical patent/WO2021038794A1/fr
Publication of WO2021038794A1 publication Critical patent/WO2021038794A1/fr

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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.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Control Of Indicators Other Than Cathode Ray Tubes (AREA)
  • Control Of El Displays (AREA)

Abstract

La présente invention élimine la détérioration de la qualité d'image d'un dispositif d'affichage à DEL tout en diminuant la consommation d'énergie du dispositif d'affichage à DEL. Le dispositif d'affichage à DEL comprend : une unité de calcul d'informations de luminosité ; une unité de sélection de valeur de courant d'attaque ; une unité de calcul de coefficient de correction de luminosité ; une unité de calcul de correction ; une unité d'affichage ; et un circuit d'attaque. L'unité de calcul d'informations de luminosité calcule des informations de luminosité à partir d'un signal vidéo. L'unité de sélection de valeur de courant d'attaque sélectionne, sur la base des informations de luminosité, une valeur de courant d'attaque parmi n types de valeurs de courant d'attaque. n représente un nombre entier supérieur ou égal à 2. L'unité de calcul de coefficient de correction de luminosité calcule, sur la base des informations de luminosité, n types de coefficients de correction de luminosité correspondant respectivement aux n types de valeurs de courant d'attaque. L'unité de calcul de correction obtient un signal vidéo corrigé en corrigeant un signal vidéo à l'aide d'un coefficient de correction de luminosité correspondant à la valeur de courant d'attaque. L'unité d'affichage comprend une pluralité de DEL. Le circuit d'attaque attaque la pluralité de DEL avec la valeur de courant d'attaque sélectionnée, selon le signal vidéo corrigé.
PCT/JP2019/033911 2019-08-29 2019-08-29 Dispositif d'affichage à del WO2021038794A1 (fr)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007149752A (ja) * 2005-11-24 2007-06-14 Denso Corp 発光素子の輝度調整装置
JP2010060746A (ja) * 2008-09-02 2010-03-18 Sharp Corp 液晶表示装置
WO2011004809A1 (fr) * 2009-07-07 2011-01-13 シャープ株式会社 Dispositif d'affichage à cristaux liquides
JP2016212239A (ja) * 2015-05-08 2016-12-15 ソニー株式会社 表示装置、表示方法、および電子機器
JP2018109753A (ja) * 2016-12-28 2018-07-12 エルジー ディスプレイ カンパニー リミテッド 有機発光表示装置、データドライバ、及びデータドライバの駆動方法

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007149752A (ja) * 2005-11-24 2007-06-14 Denso Corp 発光素子の輝度調整装置
JP2010060746A (ja) * 2008-09-02 2010-03-18 Sharp Corp 液晶表示装置
WO2011004809A1 (fr) * 2009-07-07 2011-01-13 シャープ株式会社 Dispositif d'affichage à cristaux liquides
JP2016212239A (ja) * 2015-05-08 2016-12-15 ソニー株式会社 表示装置、表示方法、および電子機器
JP2018109753A (ja) * 2016-12-28 2018-07-12 エルジー ディスプレイ カンパニー リミテッド 有機発光表示装置、データドライバ、及びデータドライバの駆動方法

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