JP2015082074A - Display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display device that suppresses degradation of display definition, and suppresses power consumption.SOLUTION: A display device 1 comprises: power consumption calculation means 12; luminance adjustment means 13; and a display panel 4. The power consumption calculation means 12 is configured to calculate consumption power 17 on the basis of display data 16. The luminance adjustment means 13 is configured to: determine whether the display data 16 is video data on the basis of a video flag 6 indicative of whether the display data is the video data; when the display data 16 is the video data, set a luminance adjustment magnification at a fixed value; when the display data 16 is not the video data, calculate a luminance adjustment magnification on the basis of the power consumption 17 calculated by the power consumption calculation means 12 and a decrease function; and calculate output data 18 subjected to the luminance adjustment on the basis of the display data 16 and the luminance adjustment magnification. The display panel 4 is configured to display the output data 18 calculated by th luminance adjustment means 13.

Description

  Embodiments described herein relate generally to a display device that controls luminance in order to suppress power consumption.

  Examples of the display device include an organic electroluminescence display device. An information terminal such as a mobile phone or a smartphone provided with a display device operates on a battery such as a lithium ion battery. For this reason, it is desirable that the power consumption of the display device be suppressed. However, the display device generally increases in power consumption as the luminance increases. Therefore, the display device may be provided with a circuit for controlling luminance in order to reduce power consumption.

JP 2011-2520 A

  As described above, the display device includes a circuit for controlling luminance. However, if the brightness is simply adjusted to reduce power consumption, the display quality may deteriorate and the display content may become unnatural.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a display device that suppresses power consumption while suppressing deterioration of display quality.

  The display device according to the first aspect includes power consumption calculating means, luminance adjusting means, and a display panel. The power consumption calculation means calculates power consumption based on the display data. The brightness adjustment means determines whether the display data is video data based on a video flag indicating whether the display data is video data. If the display data is video data, the brightness adjustment magnification is fixed and When the data is not moving image data, the brightness adjustment magnification is calculated based on the power consumption calculated by the power consumption calculation means and the decrease function, and the output data adjusted in brightness based on the display data and the brightness adjustment magnification is obtained. calculate. The display panel displays the output data calculated by the brightness adjusting means.

  The display device according to the second aspect includes power consumption calculating means, luminance adjusting means, and a display panel. The power consumption calculation means calculates power consumption based on the display data. The brightness adjusting means determines whether or not the moving image area is included in the display data frame based on moving image position data indicating the moving image area included in the display data frame. The first luminance adjustment magnification used for the first is set with a first fixed value, the second luminance adjustment magnification used for a non-moving image area that is not a moving image area of the frame is set with a second fixed value, and the moving image is displayed on the frame. When the area is not included, the third brightness adjustment magnification calculated based on the power consumption calculated by the power consumption calculation means and the decrease function is set, and the setting among the first to third brightness adjustment magnifications is set Based on the determined at least one luminance adjustment magnification and the determination result of the moving image region and the non-moving image region, output data obtained by adjusting the luminance of the frame is calculated. The display panel displays the output data calculated by the brightness adjusting means.

1 is a block diagram illustrating an example of a configuration of a display device according to a first embodiment. The graph which shows an example of the decreasing function f (x) for calculating | requiring the brightness adjustment magnification from power consumption. The graph which shows the example of the power consumption with respect to the moving image data which changes according to time, and the luminance adjustment magnification which changes according to time. The graph which shows the example of the power consumption with respect to the moving image data which changes according to time, and the fixed brightness | luminance adjustment magnification which does not change according to time. The flowchart which shows an example of a process of an electric power control part. The block diagram which shows an example of a structure of the display apparatus which concerns on 3rd Embodiment. The figure which shows an example of the display state of the web page which carried out brightness adjustment, without distinguishing a moving image area | region and a text area | region. The figure which shows an example of the display state of the Web page which adjusted the brightness | luminance by distinguishing a moving image area | region and a text area | region.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same or substantially the same functions and components are denoted by the same reference numerals, and description thereof is omitted or described as necessary.

  In each embodiment, a case where the display device is an organic electroluminescence display device will be described as an example.

(First embodiment)
The display device according to the present embodiment determines the brightness adjustment magnification based on a signal from the processor.

  FIG. 1 is a block diagram illustrating an example of a configuration of the display device 1 according to the present embodiment.

  The display device 1 includes a processor 2, a driver 3, and a display panel 4.

  The processor 2 is an application processor, for example. The processor 2 sends various signals such as display data 5 that is a differential signal and a moving image flag 6 that indicates a moving image to the driver 3. Note that the device that outputs the display data 5 or the like may be another device such as a memory device instead of the processor 2.

  The driver 3 converts the signal from the processor 2 into a signal line voltage suitable for the display panel 4. The driver 3 includes a receiver 7, an image quality adjustment unit 8, and a digital / analog converter 9. The driver 3 is an integrated circuit, for example.

  The receiver 7 receives various signals from the processor 2 and sends the various signals to the image quality adjustment unit 8.

  The image quality adjustment unit 8 receives the display data 5 and the moving image flag 6 from the receiver 7 and adjusts the luminance in order to limit the power consumed for display. The image quality adjustment unit 8 includes an image quality improvement unit 10, a power control unit 14 including a power consumption calculation unit 12 and a luminance adjustment unit 13, and a gamma conversion unit 15.

  The image quality improvement unit 10 improves the display data 5 by processing such as noise reduction, and sends the improved display data 16 to the power consumption calculation unit 12.

  Based on the improved display data 16 and a coefficient for converting the pixel value into power consumption, the power consumption calculation unit 12 calculates the power consumed to display each pixel in the frame included in the display data 16. The integrated value is calculated, frame power consumption 17 is generated, and the power consumption 17 is sent to the luminance adjustment unit 13.

  The brightness adjustment unit 13 receives the improved display data 16 from the image quality improvement unit 10, receives the moving image flag 6 from the receiver 7, and receives the power consumption 17 from the power consumption calculation unit 12.

  When the moving image flag 6 indicates that the moving image flag 6 is not moving image data, the luminance adjusting unit 13 obtains a luminance adjusting magnification that decreases as the power consumption 17 increases based on the decrease function, and calculates the pixel value of the display data 16 and the luminance adjusting magnification. Is output, and the output data 18 is sent to the gamma converter 15.

  When the moving image flag 6 indicates moving image data, the luminance adjusting unit 13 calculates the output data 18 by multiplying the pixel value of the display data 16 and the fixed luminance adjusting magnification with the luminance adjusting magnification as a fixed constant. The output data 18 is sent to the gamma converter 19.

  The brightness adjustment magnification is set to a small value such that power consumed by display is sufficiently limited, for example, a value smaller than 1.

  The gamma conversion unit 15 performs processing such as gamma conversion of the output data 18 and sends the digital signal 19 subjected to gamma conversion to the digital / analog converter 9.

  The digital / analog converter 9 converts the digital signal 19 into an analog signal 20 and applies a voltage based on the analog signal 20 to the display panel 4.

  The display panel 4 displays an image based on the signal converted by the digital / analog converter 9.

  Hereinafter, calculation of the output data 18 in the display device 1 having the above-described configuration will be specifically described. In the following, the display order of frames is assumed to be n−1 frames, n frames, and n + 1 frames.

  In the present embodiment, the display data 16 includes a plurality of frames. The power control unit 14 calculates a power consumption (for example, an integrated value of values obtained by multiplying the pixel value of the frame and a coefficient for converting the pixel value into the power consumption) 17 based on the display data 16 and calculates the calculated consumption. Based on the power 17, the brightness adjustment magnification is calculated, and the display data 16 is converted into output data 18.

  First, data conversion when the display data 16 is not moving image data will be described.

  Formula (1) is a calculation formula for calculating the power consumption 17 based on the n frames of the display data 16.

Power _n = {ΣR _{IN (n)} } × a _R + {ΣG _{IN (n)} } × a _G + {ΣB _{IN (n)} } × a _B
(1)
In Equation (1), Power _n is the power consumption 17 in n frames of the display data 16. Let R _{IN (n)} be the gradation data (corresponding to pixel value or luminance) of red pixels included in the n frame. Let G _{IN (n)} be the gradation data of the green pixels included in the n frame. The gradation data of the blue pixels included in the n frame is assumed to be B _{IN (n)} . a _R is a coefficient for converting the gradation data of the red pixel into power consumption. a _G is a coefficient for converting the gradation data of the green pixel into power consumption. a _B is a coefficient for converting the gradation data of the blue pixel into power consumption.

The moving image flag 6 indicates that n + 1 frame is not moving image data. The brightness adjustment magnification K _{n + 1} for reducing power consumption by reducing the brightness of the n + 1 frame is calculated by Expression (2).

K _{n + 1} = f (Power _n ) (2)
Here, the function f (x) is a decreasing function that satisfies f (x ₁ ) ≧ f (x ₂ ) if x ₁ <x ₂ .

  FIG. 2 is a graph showing an example of a decrease function f (x) for obtaining the brightness adjustment magnification from the power consumption 17. It is assumed that the luminance adjustment magnification is constant until the power consumption 17 reaches the threshold value, for example, 1.

  When the power consumption 17 exceeds the threshold value, the luminance adjustment magnification decreases as the power consumption 17 increases.

Let R _{IN (n + 1)} be the gradation data of the red pixel included in the n + 1 frame. Let G _{IN (n + 1)} be the gradation data of the green pixel included in the n + 1 frame. The gradation data of the blue pixel included in the n + 1 frame is assumed to be B _{IN (n + 1)} .

In this case, the gradation data R _{OUT (n + 1) of} the red pixel included in the n + 1 frame of the output data 18, the gradation data G _{OUT (n + 1) of} the green pixel included in the n + 1 frame of the output data, the output data The gradation data B _{OUT (n + 1)} of the blue pixels included in the _{(n + 1) th} frame is calculated based on the equations (3) to (5).

R _{OUT (n + 1)} = K _{n + 1} × R _{IN (n + 1)} (3)
G _{OUT (n + 1)} = K _{n + 1} × G _{IN (n + 1)} (4)
B _{OUT (n + 1)} = K _{n + 1} × B _{IN (n + 1)} (5)
If the above conversion is applied when the display data 16 is moving image data, the power consumption 17 of the display data 16 is a function of time t, and the function f (x) is also a function of time t.

  FIG. 3 is a graph showing an example of the power consumption 17 for moving image data that changes with time and the luminance adjustment magnification that changes with time. In FIG. 3, the horizontal axis indicates time, and the vertical axis indicates power consumption 17 and luminance adjustment magnification.

  When the power consumption 17 changes continuously over time, the brightness adjustment magnification also changes continuously over time. Therefore, even if there is the same gradation portion between a plurality of frames of the display data 16, the gradation is changed in the output data 18 due to the change of the luminance adjustment magnification for each of the plurality of frames, and the display content seems to fluctuate. And display quality may be reduced.

On the other hand, in the present embodiment, when the moving image flag 6 indicating that n + 1 frame is moving image data is received, the luminance adjusting unit 13 reduces the luminance and uses n + 1 frame for suppressing power consumption. The brightness adjustment magnification K _{n + 1} is fixed. Then, the gradation data R _{OUT (n + 1) of} the red pixel included in the n + 1 frame of the output data 18, the gradation data G _{OUT (n + 1) of} the green pixel included in the n + 1 frame of the output data 18, the output data The grayscale data B _{OUT (n + 1)} of blue pixels included in 18 n + 1 frames is calculated based on the fixed K _{n + 1} and the above equations (3) to (5).

  FIG. 4 is a graph showing an example of power consumption for moving image data that changes with time and a fixed luminance adjustment magnification that does not change with time. In FIG. 4, the horizontal axis indicates time, and the vertical axis indicates power consumption and luminance adjustment magnification.

Thus, when the display data 16 of the moving image data, by fixing the luminance adjustment factor K _n of the display data 16, area of the same gradation across multiple frames, the different tone in the output data 18 It is possible to prevent the display contents from fluctuating and display quality from being deteriorated.

  FIG. 5 is a flowchart illustrating an example of processing of the power control unit 14.

  In step S <b> 1, the power consumption calculation unit 12 calculates the power consumption 17 by integrating the values obtained by multiplying the pixel values of the frames included in the display data 16 and the conversion coefficients.

  In step S2, the brightness adjusting unit 13 determines whether or not the moving image flag 6 indicates that the display data 16 is moving image data.

  If the display data 16 is not moving image data, in step S3A, the luminance adjustment unit 13 calculates a luminance adjustment magnification based on the power consumption 17 and the decrease function.

  When the display data 16 is moving image data, in step S3B, the luminance adjustment unit 13 sets the luminance adjustment magnification to a fixed value for suppressing power consumption.

  In step S4, the luminance adjustment unit 13 adjusts the luminance of the display data 16 based on the luminance adjustment magnification, and obtains output data 18 that suppresses power consumption more than when the display data 16 is displayed as it is.

  In the display device 1 according to the present embodiment described above, fluctuations can be prevented even when moving image data is displayed, and power consumption is suppressed while deterioration of display quality is suppressed. Can do.

(Second Embodiment)
In the first embodiment, an example in which a frame is configured by red pixels, green pixels, and blue pixels has been described.

  However, the frame may include other color pixels.

  More specifically, for example, the frame may be composed of red pixels, green pixels, blue pixels, and white pixels.

In this case, the power consumption Power _n of the n frames is calculated based on Expression (6).

Power _n = {ΣR _{IN (n)} } × a _R + {ΣG _{IN (n)} } × a _G + {ΣB _{IN (n)} } × a _B
+ {ΣW _{IN (n)} } × a _W (6)
Here, the gradation data of the white pixels included in the n frame is defined as W _{IN (n)} . a _W is a coefficient for converting grayscale data of white pixels into power consumption.

When the display data 16 is moving image data, the gradation data W _{OUT (n + 1)} of white pixels included in the n + 1 frame of the output data 18 is calculated based on Expression (7).

W _{OUT (n + 1)} = K _{n + 1} × W _{IN (n + 1)} (7)
When the display data 16 is not moving image data, the luminance adjustment unit 13 fixes the luminance adjustment magnification K _{n + 1} of n + 1 frames used for reducing luminance and reducing power consumption. The gradation data W _{OUT (n + 1)} of the white pixel included in the n + 1 frame of the output data 18 is the white Kn + 1 included in the n + 1 frame of the fixed K _{n + 1} and the above equation (7) and the display data 16. Calculated based on pixel gradation data W _{IN (n + 1)} .

  As a result, even when white pixels are included in the frame, fluctuations in moving image data display can be prevented, and power consumption can be suppressed while deterioration of display quality is suppressed.

(Third embodiment)
The display device according to the present embodiment changes the brightness adjustment magnification for each displayed region.

  In the present embodiment, a display device that suppresses power consumption while suppressing deterioration of display quality when frames of display data 5 and 16 include a moving image region and a non-moving image region that is not a moving image will be described. In this embodiment, the case where the non-moving image area is a text area will be described as an example. However, the non-moving image area that is not a moving image may be another area such as a still image area that is not a text area. The text area is used as, for example, a comment field.

  In the present embodiment, a case where there is one moving image area in the Web page will be described as an example, but a plurality of moving image areas may be included in the Web page.

  FIG. 6 is a block diagram illustrating an example of the configuration of the display device 21 according to the present embodiment.

  In the present embodiment, the processor 22 extracts a moving image area of the display data 5. The processor 22 sends the display data 5 and moving image position data (coordinates) 23 indicating the position of the moving image area to the receiver 25 of the driver 24.

  The receiver 25 sends the moving image position data 23 to the luminance adjustment unit 27 included in the power control unit 32 of the image quality adjustment unit 26.

  Based on the moving image position data 23, the luminance adjustment unit 27 determines whether or not a moving image area is included in the frame of the display data 16. When the moving image area is included in the frame, the luminance adjusting unit 27 sets a fixed luminance adjustment magnification to the first constant for the moving image area of the frame, and fixed luminance adjustment for the text area that is not the moving image of the frame. Set the magnification to the second constant. The luminance adjustment unit 27 sets the luminance adjustment magnification calculated based on the power consumption 17 calculated by the power consumption calculation unit 12 and the decrease function when the moving image area is not included in the frame. Then, the luminance adjustment unit 27 performs luminance adjustment on a frame including the moving image region and the text region or a frame not including the moving image region based on the set luminance adjustment magnification, the pixel value of the frame, and the pixel position. The output data 28 is generated, and the output data 28 is sent to the gamma conversion unit 15.

  The display panel 4 displays a web page in which a moving image is embedded, for example, with a browser.

  FIG. 7 is a diagram illustrating an example of a display state of the Web page 31 in which the brightness is adjusted without distinguishing between the moving image area 29 and the text area 30. In FIG. 7, the power consumption changes with time, and the brightness adjustment magnification also changes according to the power consumption.

  When the brightness adjustment magnification is simply obtained from the power consumption of the frame of the display data 16 without distinguishing between the moving image area 29 and the text area 30 of the Web page 31, the text is affected by the change in the luminance of the moving image area 29. The brightness of the area 30 is also adjusted, and the brightness (brightness) of the text area 30 that is originally the background changes, which may deteriorate the display quality.

  FIG. 8 is a diagram illustrating an example of a display state of the Web page 31 in which the brightness adjustment is performed by distinguishing the moving image area 29 and the text area 30. In FIG. 8, the luminance adjustment magnification is fixed in both the moving image area 29 and the text area 30 even if the power consumption changes.

  In the present embodiment, the driver 24 receives the moving image position data 23 along with the display data 5 from the processor 22.

  In the present embodiment, a fixed first luminance adjustment magnification for the moving image region 29 is set for the Web page 31 including the moving image region 29 and the text region 30, and a fixed second luminance adjustment for the text region 30 is set. Set the magnification.

Here, the upper left point P ₁ of the moving image area 29 is (x ₁ , y ₁ ), and the lower right point P ₂ of the moving image area 29 is (x ₂ , y ₂ ).

  In this case, the luminance adjustment unit 27 converts the n + 1 frame and generates output data 28 as follows. Here, the luminance adjustment related to the red pixel will be described, but the same applies to pixels of other colors such as a green pixel, a blue pixel, and a white pixel.

R _{OUT (n + 1)} = K _{n + 1} × R _{IN (n + 1)} (when x ₁ ≦ R _x ≦ x ₂ and y ₁ ≦ R _y ≦ y ₂ )
(8)
R _{OUT (n + 1)} = L _{n + 1} × R _{IN (n + 1)}
(When R _x <x ₁ , x ₂ <R _x , R _y <y ₁ , y ₂ <R _y ) (9)
Here, R _x is the X coordinate of the red pixel, and R _y is the Y coordinate of the red pixel. K _{n + 1} is a constant, and L _{n + 1} is a constant. For example, when K _{n + 1} is larger than L _{n + 1} , the luminance of the text region 30 is suppressed to suppress power consumption, and the luminance of the moving image region 29 is not suppressed as much as the text region 30. For this reason, it is possible to suppress a decrease in display quality of the moving image area 29 while suppressing power consumption. For example, when K _{n + 1} is smaller than L _{n + 1} , the luminance of the moving image region 29 having a large change is suppressed more than the luminance of the text region 30 having a small change.

  Note that when the Web page 31 does not include the moving image area 29, the brightness adjustment magnification changes based on the power consumption and the decrease function, as in the first embodiment.

  In the present embodiment described above, an appropriate fixed luminance adjustment magnification is set for each of the moving image area 29 and the text area 30 in the Web page 31 including the moving image area 29 and the text area 30. As a result, the luminance of the text area 30 is not adjusted by being affected by the fluctuation of the luminance of the moving image area 29, and the change of the light and darkness of the text area 30 that is originally the background is suppressed. Deterioration of display quality can be prevented.

  This embodiment is presented as an example and is not intended to limit the scope of the invention. The novel embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. This embodiment and its modifications are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1,21 ... Display apparatus, 2,22 ... Processor, 3,24 ... Driver, 4 ... Display panel, 5,16 ... Display data, 6 ... Movie flag, 7, 25 ... Receiver, 8, 26 ... Image quality adjustment part, DESCRIPTION OF SYMBOLS 9 ... Digital / analog converter, 10 ... Image quality improvement part, 12 ... Power consumption calculation part, 13, 27 ... Luminance adjustment part, 14, 32 ... Power control part, 15 ... Gamma conversion part, 17 ... Power consumption, 18, 28 ... Output data, 19 ... Digital signal, 20 ... Analog signal, 23 ... Movie position data, 29 ... Movie area, 30 ... Text area, 31 ... Web page.

Claims (2)

Power consumption calculating means for calculating power consumption based on display data;
Based on a moving image flag indicating whether or not the display data is moving image data, it is determined whether or not the display data is the moving image data, and when the display data is the moving image data, a luminance adjustment magnification is set to a fixed value, When the display data is not the moving image data, the brightness adjustment magnification is calculated based on the power consumption calculated by the power consumption calculation means and the decrease function, and based on the display data and the brightness adjustment magnification. Brightness adjusting means for calculating brightness adjusted output data;
A display panel for displaying the output data calculated by the brightness adjusting means;
A display device comprising: Power consumption calculating means for calculating power consumption based on display data;
Based on the moving image position data indicating the moving image area included in the frame of the display data, it is determined whether the moving image area is included in the frame of the display data, and when the moving image area is included in the frame, A first luminance adjustment magnification used for the moving image area is set with a first fixed value, and a second luminance adjustment magnification used for a non-moving image area other than the moving image area of the frame is set with a second fixed value. When the moving image area is not included in the frame, a third brightness adjustment magnification calculated based on the power consumption calculated by the power consumption calculation unit and the decrease function is set, and the first to first Output data obtained by adjusting the brightness of the frame on the basis of at least one brightness adjustment magnification set out of the brightness adjustment magnifications of 3 and the determination result of the moving image area and the non-moving image area. And luminance adjustment means for calculating,
A display panel for displaying the output data calculated by the brightness adjusting means;
A display device comprising:

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