JP6799419B2 - Image display device, drive method and drive program - Google Patents

Description

The present invention relates to an image display device, a driving method, and a driving program using a current-driven light emitting element.

Conventionally, an active matrix type image display device such as an organic EL performs luminance modulation by controlling a current supplied to a light emitting element by using a thin film transistor (TFT). However, since the TFTs used for driving have different characteristics, there is a problem that even if the same voltage is applied, the amount of current flowing through the light emitting element of each pixel is different, resulting in uneven brightness and deterioration of display quality. is there. In order to reduce such variations in characteristics, the image display device compensates for variations inside the display panel (see, for example, Patent Document 1).

JP-A-2007-133282

However, due to the high definition and high dynamic range of the display panel, the current supplied to each light emitting element becomes small, so that the compensation for the variation in characteristics becomes insufficient. For example, in the technique of Patent Document 1, a correction period is provided in the drive signal to correct the threshold value and the mobility of the TFT. However, in the low gradation portion, the current flowing through the pixel is small, so that the brightness is sufficient. I couldn't correct it.

An object of the present invention is to provide an image display device, a driving method, and a driving program capable of reducing luminance unevenness in a low gradation portion.

The image display device according to the present invention includes an extraction unit for extracting a low gradation region of an image, a division unit for dividing the low gradation region into a small region including a plurality of pixels, and the said small region included in the small region. It is provided with an adjusting unit that causes only a light emitting element corresponding to a part of the plurality of pixels to emit light with a light emitting intensity adjusted according to the number of pixels in the small region.

The adjusting unit may sequentially replace some of the plurality of pixels included in the small area for each video frame to emit light.

The adjusting unit may increase the emission intensity by a magnification based on the ratio of the part of the pixels.

The adjusting unit may adjust the emission intensity of some of the pixels so as to be the sum of the emission intensities of the plurality of pixels.

The divided portion may increase the number of pixels in the small region as the gradation in the low gradation region is lower.

The display panel driving method according to the present invention includes an extraction step of extracting a low gradation region of an image, a division step of dividing the low gradation region into a small region including a plurality of pixels, and a division step of dividing the low gradation region into a small region including a plurality of pixels in an image display device. The computer executes an adjustment step of causing only a light emitting element corresponding to a part of the plurality of pixels included in the small area to emit light with a light emitting intensity adjusted according to the number of pixels in the small area.

The display panel drive program according to the present invention includes an extraction step of extracting a low gradation region of an image, a division step of dividing the low gradation region into a small region including a plurality of pixels, and a division step of dividing the low gradation region into a small region including a plurality of pixels in an image display device. The computer is made to perform an adjustment step of causing only a light emitting element corresponding to a part of the plurality of pixels included in the small area to emit light with a light emitting intensity adjusted according to the number of pixels in the small area.

According to the present invention, it is possible to reduce the luminance unevenness of the low gradation portion in the image display device.

It is a block diagram which shows the structure of the image display device which concerns on embodiment. It is a figure which illustrates the small area which concerns on embodiment. It is a figure which shows the 1st adjustment method of the signal level which concerns on embodiment. It is a figure which shows the 2nd adjustment method of the signal level which concerns on embodiment. It is a figure which shows an example of the circuit which comprises each pixel which concerns on embodiment.

Hereinafter, an example of the embodiment of the present invention will be described.
The image display device 1 according to the present embodiment is a display device using an organic EL light emitting element, and is a low gradation region by using spatial modulation that adjusts the light emission intensity on a pixel-by-pixel basis in signal processing for each video frame. It suppresses the decrease of the current in the above and reduces the unevenness of brightness.

FIG. 1 is a block diagram showing a configuration of an image display device 1 according to the present embodiment.
The image display device 1 includes a signal processing unit 10, a row drive driver unit 20, a column drive driver unit 30, and a display panel 40.

The signal processing unit 10 receives the image data included in the video signal as an input, determines the gradation value of each pixel, and controls the row drive driver unit 20 and the column drive driver unit 30 to control the light emitting element of the display panel 40. Is emitted with a drive current according to the gradation value.

The row drive driver unit 20 receives a control signal for scanning each horizontal line from the signal processing unit 10.
Further, a plurality of selection signal lines and power supply lines to each light emitting element are vertically connected from the row drive driver unit 20 to each pixel of the display panel 40. The row drive driver unit 20 supplies a selection signal to each of the plurality of selection signal lines, and applies a drive voltage from the power supply line.

The column drive driver unit 30 receives the data of the gradation value determined by the signal processing unit 10.
Further, a plurality of data signal lines are connected in the horizontal direction from the column drive driver unit 30 to each pixel of the display panel 40. The column drive driver unit 30 supplies a data signal based on the gradation value of each pixel to each of the plurality of data signal lines.

The display panel 40 is a display device in which an organic EL light emitting element is provided corresponding to each pixel, and each light emission is performed in response to a control signal from the row drive driver unit 20 and a data signal from the column drive driver unit 30. An image is displayed by causing the element to emit light.

Next, the function of the signal processing unit 10 will be described in detail.
As shown in FIG. 1, the signal processing unit 10 includes an extraction unit 11, a division unit 12, and an adjustment unit 13.

The extraction unit 11 extracts a region (low gradation region) having a low signal level (gradation value) from the input image data for each video frame to form a divided light emitting region, and the region having a high video level is a normal light emitting region. And.

The dividing unit 12 divides the divided light emitting region into a small region including a plurality of pixels.
The adjusting unit 13 causes only a light emitting element corresponding to a part of the plurality of pixels included in the small area to emit light with a light emitting intensity adjusted according to the number of pixels in the small area. That is, the adjusting unit 13 adjusts the signal level of a specific pixel representing a plurality of pixels to a high level, and causes only the specific pixel to emit light, thereby suppressing a decrease in the drive current.

FIG. 2 is a diagram illustrating a small area according to the present embodiment.
For example, in the divided light emitting region 50, a small region 51 for every four pixels is provided.
In the divided light emitting region, the pixels that emit light are determined for each video frame, and among the plurality of pixels included in the small area 51, the pixels to be emitted are sequentially replaced. For example, assuming that each pixel in the small region is A, B, C, and D, the pixels A and D emit light in the odd frame, and the pixels B and C emit light in the even frame.

FIG. 3 is a diagram showing a first method of adjusting the signal level according to the present embodiment.
To compensate for the luminance of the pixels do not emit light by the pixel to emit light, the adjustment unit 13, in the odd frame, the pixel A of FIG. 2, B, C, the signal level of the _{D S A, S B, S} C, the _{S D} , _{S a} respectively ', 0,0, _{S D'} is converted, in the even frame, respectively _{0, S B ', S C} ', is converted to 0.

Here, the adjusting unit 13 increases the emission intensity by a magnification based on the ratio of some pixels to be emitted. More specifically, in order to compensate for the brightness of the four pixels 2 pixels as in example 2, so that the brightness based on the signal level is doubled, the signal level S _{A 'is} converted, conversion It is converted to √2 times the previous signal level S _a.
In the normal light emitting region with high brightness, the adjusting unit 13 does not convert the signal level.

FIG. 4 is a diagram showing a second adjustment method of the signal level according to the present embodiment.
In the first adjusting method (FIG. 3), the adjusting section 13 is obtained by converting the signal level S _A at a predetermined magnification, the second adjustment method, using a signal level of the other pixels in the small area, The emission intensity of some pixels is adjusted so as to be the sum of the emission intensities of a plurality of pixels.

Specifically, adjustment unit 13, the signal level when converting from S _A to S _{A ',} not to emit light pixel (e.g., pixel B) to compensate for the brightness of the average of the S _A and S _B √2 times to seek the _{S a} '.

FIG. 5 is a diagram showing an example of a circuit constituting each pixel of the display panel 40 according to the present embodiment.
At the timing when the voltage Vga is applied from the selection signal line, when the voltage Vda corresponding to the signal level of the pixel is applied from the data signal line, the data voltage is written to the capacitor C1 via the transistor Tr1.

At this time, by applying the drive voltage Vdd at the same time, the brightness unevenness due to the variation in the mobility of Tr1 is corrected. However, when the voltage of Vda is low, a sufficient current does not flow and the correction of variation becomes insufficient. By converting the signal level in the low gradation region to a high level by the signal processing unit 10, the effect of correcting the variation can be enhanced.

After that, a current flows through the transistor Tr2 to the organic EL element Del by the drive voltage Vdd, and the light is emitted. Since the signal level is raised in order to enhance the correction effect, there are pixels that increase the brightness, but since the pixels that do not emit light are specified for each frame, the change in the overall brightness level is suppressed. The image is displayed.
Further, in the case of a high frame rate (for example, 120 Hz or more), the influence of flicker caused by the switching of the light emitting pixels can be avoided.

According to the present embodiment, the image display device 1 extracts a low gradation region of an image in the signal processing unit 10, divides the low gradation region into small regions of a plurality of pixels, and each of the small regions is divided into small regions. Only a part of the pixels is controlled to emit light by adjusting the light emission intensity according to the number of divisions. Therefore, the image display device 1 can reduce the luminance unevenness in the low gradation portion even if the current per pixel becomes small.

Further, the image display device 1 sequentially replaces some of the plurality of pixels included in the small area, which are the targets of light emission, for each video frame. Therefore, the image display device 1 can evenly select the pixels to be emitted for each frame at the time of reproducing the moving image, and can suppress the deterioration of the image quality.

At this time, the image display device 1 can reduce the luminance unevenness in the low gradation portion by a simple method with a low processing load by increasing the emission intensity by a magnification based on the ratio of the pixels to be emitted.
Alternatively, the image display device 1 can more faithfully reproduce the brightness of the original image data by adjusting the emission intensity of the pixels to be emitted so as to be the sum of the emission intensities of the plurality of pixels in the small region.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments. Further, the effects described in the present embodiment merely list the most preferable effects arising from the present invention, and the effects according to the present invention are not limited to those described in the present embodiment.

In the present embodiment, the image display device 1 divides the pixels in the small area into two groups (A, C) and (B, D) for each frame, and each group emits light alternately. It may be divided into. For example, the image display device 1 may divide the pixels into A, B, C, and D, and control each of them to emit light once every four frames.

Further, the image display device 1 may increase the number of pixels in the small region as the gradation in the extracted low gradation region is lower. As a result, the image display device 1 can appropriately increase the gradation value after conversion and reduce the luminance unevenness in the low gradation portion.
The size of the small area may be constant in one frame, or may be divided so that small areas of a plurality of sizes coexist in one frame.

The image to be processed by the image display device 1 is not limited to a moving image in which a plurality of frames are continuous, and may be a still image.

In the present embodiment, the configuration and operation of the image display device 1 have been mainly described, but the present invention is not limited to this, and each component may be provided and configured as a method or a program for displaying an image. ..

Further, the program for realizing the function of the image display device 1 may be recorded on a computer-readable recording medium, and the program recorded on the recording medium may be read by the computer system and executed. Good.

The term "computer system" as used herein includes hardware such as an OS and peripheral devices. Further, the "computer-readable recording medium" refers to a portable medium such as a flexible disk, a magneto-optical disk, a ROM, or a CD-ROM, or a storage device such as a hard disk built in a computer system.

Furthermore, a "computer-readable recording medium" is a communication line that transmits a program via a network such as the Internet or a communication line such as a telephone line, and dynamically holds the program for a short period of time. It may also include a program that holds a program for a certain period of time, such as a volatile memory inside a computer system that serves as a server or a client in that case. Further, the above-mentioned program may be a program for realizing a part of the above-mentioned functions, and may be a program for realizing the above-mentioned functions in combination with a program already recorded in the computer system. ..

1 Image display device 10 Signal processing unit 11 Extraction unit 12 Division unit 13 Adjustment unit 20-row drive driver unit 30-column drive driver unit 40 Display panel

Claims (6)

An extraction unit that extracts the low gradation area of the image,
A division portion that divides the low gradation region into a small region including a plurality of pixels, and
A light emitting element corresponding to a part of the plurality of pixels included in the small area is provided with an adjusting unit for emitting light with a light emitting intensity adjusted according to the number of pixels in the small area .
The adjustment unit, for each video frame, said one of said plurality of pixels included in the small region, an image display device Ru replaced the portion of the pixel which is the target to emit light sequentially. The image display device according to claim 1, wherein the adjusting unit increases the light emission intensity by a magnification based on the ratio of some of the pixels. The image display device according to claim 1, wherein the adjusting unit adjusts the light emitting intensity of some of the pixels so as to be the total of the light emitting intensities of the plurality of pixels. The image display device according to any one of claims 1 to 3 , wherein the divided portion increases the number of pixels in the small region as the gradation in the low gradation region is low. In the image display device
An extraction step to extract the low gradation area of the image,
A division step of dividing the low gradation region into a small region including a plurality of pixels,
The computer executes an adjustment step of causing only a light emitting element corresponding to a part of the plurality of pixels included in the small area to emit light with a light emitting intensity adjusted according to the number of pixels in the small area .
In the adjustment step, for each video frame, the small region of the plurality of pixels included, the driving method of interchanging Ru display panel a part of the pixel in the order is subject to emit light. In the image display device
An extraction step to extract the low gradation area of the image,
A division step of dividing the low gradation region into a small region including a plurality of pixels,
A computer is made to execute an adjustment step of causing only a light emitting element corresponding to a part of the plurality of pixels included in the small area to emit light with a light emitting intensity adjusted according to the number of pixels in the small area .
Wherein in the adjustment step, for each video frame, said one of said plurality of pixels included in the small region, the operating program of the display panel because let swapping a part of the pixel in the order is subject to emit light.

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