JP6910766B2 - Display device - Google Patents

Description

The present invention relates to a display device.

It is desired to improve the upper limit of the brightness of the image (display image) displayed on the display device and to improve the contrast of the displayed image. In the liquid crystal display device, the white display brightness (screen brightness) can be increased and the black display brightness can be reduced by performing local deming control of the backlight unit. As a result, both the upper limit of the brightness of the display image and the contrast of the display image can be improved. Local demming control is disclosed in, for example, Patent Document 1.

In the local demming control, the emission brightness of each of the plurality of light source units included in the backlight unit is individually controlled. Therefore, when the transmittance of the liquid crystal panel is controlled to the transmittance according to the input image data, the image quality of the displayed image may be deteriorated by the local deming control. Specifically, when the emission brightness of the backlight unit changes from the reference emission brightness by the local deming control, the display brightness corresponding to the input image data cannot be realized. Further, if the emission brightness of the light source unit varies among the plurality of light source units due to the local demming control, the brightness unevenness occurs in the displayed image.

As a method for suppressing such deterioration of image quality, the incident brightness (the brightness of the light emitted from the backlight unit at the time of incident on the liquid crystal panel) is estimated, and the input image data is based on the estimated incident brightness. A method of correcting the above has been proposed. By controlling the transmittance of the liquid crystal panel to the transmittance according to the corrected image data, it is possible to realize the display brightness according to the input image data at each position on the screen.

However, even if the input image data is corrected based on the estimated incident brightness, other image quality deterioration of the displayed image may occur due to the local deming control. Specifically, when the emission brightness of the backlight unit suddenly changes due to local deming control, flicker called "flicker" occurs on the screen. Such flicker can be suppressed by suppressing the time change (time change) of the emission brightness of the backlight unit.

Further, if the emission brightness of the backlight unit is increased, the display brightness can be increased, but the power consumption of the backlight unit increases. There is an upper limit to the electric power (electric power that can be output to the liquid crystal display device, electric power that can be input to the liquid crystal display device, etc.), and by increasing the emission brightness of the backlight unit, the electric power required for the liquid crystal display device. (Required power) may exceed the upper limit. By correcting the drive value of each light source unit, it is possible to suppress the excess of the required power with respect to the upper limit. The drive value is a value that controls the emission brightness of the light source unit. However, the emission brightness of the backlight unit may change abruptly due to the correction of the drive value of each light source unit, and flicker may occur on the screen. Such flicker can be suppressed by suppressing the time change of the drive value of each light source unit.

Here, as a method of estimating the incident brightness, there are a first method of estimating the incident brightness based on the target brightness of each light source unit and a second method of estimating the incident brightness based on the drive value of each light source unit. Conceivable. However, the emission brightness of each light source unit may be controlled to the emission brightness that is significantly different from the target brightness by correcting the drive value or the like. Therefore, in the first method, deterioration of the image quality of the displayed image cannot be suppressed with high accuracy. Further, when the luminous efficiency of the light source unit varies among the plurality of light source units, the drive value for achieving a certain emission brightness varies among the plurality of light source units. Therefore, in order to estimate the incident brightness with high accuracy by the second method, it is necessary to consider the luminous efficiency of each light source unit, which increases the processing load.

Japanese Unexamined Patent Publication No. 2002-99250

An object of the present invention is to provide a technique capable of suppressing deterioration of image quality of a displayed image with high accuracy with a simple configuration.

The first aspect of the present invention is
A light emitting means having a plurality of light source units and
A display means for displaying an image by modulating the light emitted from the light emitting means based on the image data, and a display means.
For each light source unit, a first determination means for determining the first target brightness, which is the target brightness of the light source unit, based on the input image data, and
The first correction for acquiring the second target brightness of each light source unit by performing the first correction process for correcting the first target brightness for each light source unit so that the time change of the target brightness between frames is suppressed. Means and
For each light source unit, a second determination means for determining a first drive value, which is a drive value for controlling the emission brightness of the light source unit, based on the second target brightness.
A second correction means for acquiring the second drive value of each light source unit by performing a second correction process for correcting the first drive value for each light source unit so that the time change of the drive value is suppressed.
An estimation means that estimates the incident brightness, which is the brightness of the light emitted from the light emitting means when it is incident on the display means, based on the second target brightness of each light source unit.
A third correction means that corrects the input image data based on the incident brightness estimated by the estimation means, and
The first parameter used in the first correction process and the second correction process so that the difference between the second target brightness of each light source unit and the actual emission brightness of each light source unit is equal to or less than the first threshold value. A setting means for setting both the second parameter used in
A reception means that can accept requests from users,
Have a,
The plurality of light source units are driven using the second drive value, and the plurality of light source units are driven.
The display means modulates the light emitted from the light emitting means based on the input image data corrected by the third correction means.
The setting means, when the request is made,
As the first parameter, a first value according to the request is set, and the first value is set.
The display device is characterized in that a second value according to the request is set as the second parameter.

A second aspect of the present invention is
A light emitting means having a plurality of light source units and
A control method for a display device including a display means for displaying an image by modulating the light emitted from the light emitting means based on image data.
For each light source unit, the first determination step of determining the first target brightness, which is the target brightness of the light source unit, based on the input image data, and
The first correction for acquiring the second target brightness of each light source unit by performing the first correction process for correcting the first target brightness for each light source unit so that the time change of the target brightness between frames is suppressed. Steps and
For each light source unit, a second determination step of determining a first drive value, which is a drive value for controlling the emission brightness of the light source unit, based on the second target brightness.
A second correction step of acquiring the second drive value of each light source unit by performing a second correction process of correcting the first drive value for each light source unit so that the time change of the drive value is suppressed.
An estimation step of estimating the incident brightness, which is the brightness of the light emitted from the light emitting means at the time of incidence on the display means, based on the second target brightness of each light source unit.
A third correction step that corrects the input image data based on the incident brightness estimated in the estimation step, and
The first parameter used in the first correction process and the second correction process so that the difference between the second target brightness of each light source unit and the actual emission brightness of each light source unit is equal to or less than the first threshold value. Setting steps to set both with the second parameter used in
The reception step to receive the request from the user and
Have,
The plurality of light source units are driven using the second drive value, and the plurality of light source units are driven.
The display means modulates the light emitted from the light emitting means based on the input image data corrected in the third correction step.
In the setting step, when the request is made,
As the first parameter, a first value according to the request is set, and the first value is set.
The control method is characterized in that a second value according to the request is set as the second parameter.

A third aspect of the present invention is a program for causing a computer to execute each step of the control method according to the second aspect of the present invention.

According to the present invention, deterioration of the image quality of the displayed image can be suppressed with high accuracy with a simple configuration.

Block diagram showing a configuration example of the display device according to the first embodiment The figure which shows an example of the input image data which concerns on Example 1 and the feature amount thereof. The figure which shows an example of the feature amount, the reference luminance, and the target luminance which concerns on Example 1. The figure which shows an example of the emission brightness and the drive time which concerns on Example 1. The figure which shows an example of the input image data which concerns on Example 1. The figure which shows an example of the target luminance which concerns on Example 1. The figure which shows an example of the drive value which concerns on Example 1. The figure which shows an example of the drive value which concerns on Example 1. The figure which shows an example of the actual emission brightness which concerns on Example 1. The figure which shows an example of the time constant which concerns on Example 1. Block diagram showing a configuration example of the display device according to the second embodiment

<Example 1>
Hereinafter, Example 1 of the present invention will be described. In the following, an example in which the display device according to this embodiment is a transmissive liquid crystal display device will be described, but the display device according to this embodiment is not limited to the transmissive liquid crystal display device. The display device according to the present embodiment may be any display device having a light emitting unit and a display unit that displays an image by modulating the light from the light emitting unit based on the image data. For example, the display device according to this embodiment may be a reflective liquid crystal display device. Further, the display device according to the present embodiment may be a MEMS shutter type display device using a MEMS (Micro Electro Mechanical System) shutter instead of the liquid crystal element.

FIG. 1 is a block diagram showing a configuration example of the display device 1 according to the present embodiment. The display device 1 includes a liquid crystal panel unit 2, a backlight unit 3, a feature amount acquisition unit 4, a BL reference brightness determination unit 5, a BL brightness determination unit 6, a first time LPF processing unit 7, a BL brightness storage unit 8, and an incident brightness. It has an estimation unit 9, an image correction value determination unit 10, and an image correction unit 11. Further, the display device 1 includes an RGB-BL brightness determination unit 12, a drive time determination unit 13, a total drive time determination unit 14, a time correction value determination unit 15, a time correction value selection unit 16, a drive time correction unit 17, and a second. It has a time LPF processing unit 18 and a drive time storage unit 19. Further, the display device 1 includes a BL brightness detection unit 20, a second correction value determination unit 21, a first correction value storage unit 22, a user I / F unit 23, a scene change detection unit 24, and a parameter setting unit 25. ..

The liquid crystal panel unit 2 displays an image by modulating the light from the backlight unit 3 based on the image data. In this embodiment, the liquid crystal panel unit 2 includes a liquid crystal driver, a control substrate, and a liquid crystal panel. The liquid crystal panel has a plurality of liquid crystal elements. The control board controls the processing of the liquid crystal driver based on the image data input to the liquid crystal panel unit 2. The liquid crystal driver drives each liquid crystal element of the liquid crystal panel in response to an instruction from the control board (instruction based on image data). As a result, the transmittance (aperture ratio; modulation ratio) of each liquid crystal element is controlled to a value based on the image data input to the liquid crystal panel unit 2. The light from the backlight unit 3 passes through each liquid crystal element, so that an image is displayed on the screen.

The backlight unit 3 has a plurality of light source units. Each light source unit has one or more light sources (light emitting elements). As the light source, a light emitting diode (LED), an organic EL element, a cold cathode tube, or the like can be used. In this embodiment, the backlight unit 3 has a plurality of light sources, a control circuit for controlling light emission of each light source, and an optical unit for diffusing the light emitted from each light source. The backlight unit 3 has, for example, m horizontal direction × n vertical direction light source units. In this embodiment, the backlight unit 3 has 10 light sources in the horizontal direction and 6 light sources in the vertical direction. Further, in this embodiment, each light source unit has a plurality of color light source units having different emission colors. Specifically, each light source unit is an R light source unit that is a color light source unit that emits red light, a G light source unit that is a color light source unit that emits green light, and a B light source unit that is a color light source unit that emits blue light. Has. Each color light source unit has one or more light sources. For example, R-LED, which is an LED that emits red light, is used as an R light source unit, G-LED, which is an LED that emits green light, is used as a G light source unit, and B-LED, which is an LED that emits blue light, is B. Used as a light source unit. In this embodiment, a plurality of light sources are mixed so that the red light from the R light source unit, the green light from the G light source unit, and the blue light from the B light source unit are mixed and become white light on the back surface of the liquid crystal panel. A unit, an optical unit, and a liquid crystal panel are arranged.

The color light source unit is not limited to the R light source unit, the G light source unit, and the B light source unit. The backlight unit 3 may not have at least one of an R light source unit, a G light source unit, and a B light source unit. The backlight unit 3 may have a Y light source unit or the like, which is a color light source unit that emits yellow light. Further, the arrangement of the plurality of light source units is not limited to the matrix-like arrangement. For example, a plurality of light source units may be arranged in a houndstooth pattern.

In this embodiment, a plurality of light source units are associated with a plurality of divided areas constituting a screen area. The feature amount acquisition unit 4 acquires the feature amount in the image area (image area displayed in the divided area) corresponding to the divided area of the light source unit from the input image data for each of the plurality of light source units. Then, the feature amount acquisition unit 4 notifies (outputs) the feature amount acquired for each light source unit to the BL reference luminance determination unit 5 and the scene change detection unit 24. In this embodiment, the feature amount acquisition unit 4 acquires the maximum value of the gradation value in the image area corresponding to the divided area as the feature amount for the light source unit of the divided area.

Here, the RGB image data in which each pixel value is an RGB value (a combination of an R value which is a red gradation value, a G value which is a green gradation value, and a B value which is a blue gradation value) is Consider the case where it is acquired as input image data. In this case, the maximum R value (maximum value of R value) may be acquired as a feature amount, the maximum G value (maximum value of G value) may be acquired as a feature amount, or the maximum B value. (Maximum value of B value) may be acquired as a feature amount. The maximum value among the maximum R value, the maximum G value, and the maximum B value may be acquired as a feature amount. The Y value (luminance value) may be calculated from the RGB value for each pixel. Then, the maximum value of the Y value may be acquired as a feature amount.

A specific example of the processing of the feature amount acquisition unit 4 will be described with reference to FIGS. 2 (A) and 2 (B). FIG. 2A shows an example of input image data. FIG. 2A shows an example in which the gradation value of the input image data is a 10-bit value (0 to 1023). In FIG. 2 (A), the larger the gradation value, the more (
The gradation value is shown in a color closer to white (the higher the brightness) and closer to black as the gradation value is smaller (the lower the brightness). In FIG. 2A, white corresponds to the gradation value 1023, and black corresponds to the gradation value 0. In the input image data of FIG. 2A, there are three objects having a gradation value of 1023 (two quadrangular objects and one circular object). Then, in the input image data of FIG. 2A, the gradation value of the background changes from 512 to 0 in the direction from left to right.

FIG. 2B shows an example of the feature amount acquired for each divided region (each light source unit). FIG. 2B shows the feature amount acquired from the input image data of FIG. 2A. In FIG. 2B, the numerical values (1 to 10) arranged in the horizontal direction indicate the horizontal position (position in the horizontal direction) of the divided region, and the numerical values (1 to 6) arranged in the vertical direction indicate the horizontal position of the divided region. Indicates the vertical position (position in the vertical direction). As shown in FIG. 2B, 1023 is acquired as a feature amount (maximum value of gradation value; maximum gradation value) in the divided region including at least a part of the object. Then, in the divided region that does not include the object, the feature amount changes from 512 to 0 as the horizontal position increases.

The area corresponding to the light source unit (corresponding area) is not limited to the above-mentioned divided area. The corresponding area may be separated from the other corresponding area, or at least a part of the corresponding area may overlap with at least a part of the other corresponding area. The correspondence between the corresponding region and the light source does not have to be a one-to-one correspondence. For example, two or more light sources may be associated with one corresponding region. The corresponding area may be a part of the screen area or the entire screen area.

The input image data is not limited to RGB image data. For example, YCbCr image data in which each pixel value is a YCbCr value (a combination of a Y value which is a luminance value, a Cb value which is a color difference value, and a Cr value which is a color difference value) may be acquired as input image data. .. Further, the feature amount is not particularly limited. For example, as the feature amount, other representative values of gradation values (minimum value, average value, median value, mode value, etc.), a histogram of gradation values, and the like may be used. A common feature amount may be acquired among a plurality of light source units. For example, as a feature amount common to a plurality of light source units, a feature amount corresponding to the entire image area of the input image data may be acquired.

The BL reference brightness determining unit 5 determines the reference brightness, which is the reference of the emission brightness (emission amount) of the light source unit, for each of the plurality of light source units. Then, the BL reference brightness determination unit 5 notifies the BL brightness determination unit 6 of the reference brightness of each light source unit. In this embodiment, the BL reference brightness determining unit 5 determines the reference brightness of each of the plurality of light source units according to the feature amount acquired for the light source unit.

In this embodiment, a look-up table (LUT) showing the correspondence relationship shown in FIG. 3A is prepared in advance. The correspondence relationship in FIG. 3A is a correspondence relationship between the feature amount and the reference luminance. The horizontal axis of FIG. 3 (A) shows the feature amount, and the vertical axis of FIG. 3 (A) shows the reference luminance. The reference brightness (emission brightness) 0 [%] corresponds to the state in which the light source unit is turned off, and the reference brightness 100 [%] corresponds to the state in which the light source unit emits light at the upper limit emission brightness. The BL reference luminance determination unit 5 determines the reference luminance from the feature amount using the LUT. When the feature amount of FIG. 2 (B) is acquired, the reference luminance of FIG. 3 (B) is determined from the correspondence relationship of FIG. 3 (A).

The method for determining the reference luminance is not limited to the above method. For example, instead of the LUT, a function indicating the correspondence between the feature amount and the reference luminance may be used. The correspondence between the feature amount and the reference luminance is not limited to the correspondence in FIG. 3 (A). The correspondence between the feature amount and the reference brightness is not particularly limited. The BL reference luminance determination unit 5 may rewrite the LUT and use it in response to an instruction from the parameter setting unit 25. The parameter setting unit 25 may notify the BL reference luminance determination unit 5 of the LUT, and the notified LUT may be used by the BL reference luminance determination unit 5. The parameter setting unit 25 gives an instruction for rewriting the LUT, a notification of the LUT, and the like, for example, in response to a request from the user. Depending on the type of input image data, the usage environment of the display device 1, and the like, instructions for rewriting the LUT, notification of the LUT, and the like may be given.

The BL brightness determination unit 6 determines, for each of the plurality of light source units, the target brightness, which is the target of the emission brightness of the light source unit, based on the input image data. That is, the BL brightness determination unit 6 individually determines the target brightness of each light source unit based on the input image data. Hereinafter, the target luminance determined by the BL luminance determination unit 6 will be referred to as "first target luminance". Then, the BL brightness determination unit 6 notifies the first time LPF processing unit 7 of the first target brightness of each light source unit. In the present embodiment, the BL brightness determining unit 6 corresponds to each of the plurality of light source units based on the reference brightness determined for the light source unit and the brightness specified by the user (user-specified brightness). The first target brightness of the light source unit is determined. In this embodiment, the upper limit of the display brightness (screen brightness) is specified by the user. The "upper limit of display brightness" can also be said to be "display brightness corresponding to the upper limit of the gradation value". The user-specified luminance is notified from the parameter setting unit 25 to the BL luminance determination unit 6, for example, in response to a request from the user. The user-specified brightness is not limited to the upper limit of the display brightness. For example, the display brightness corresponding to another gradation value smaller than the upper limit of the gradation value may be specified by the user. Further, the method for determining the first target brightness is not particularly limited. For example, the reference brightness may be used as the first target brightness.

The first target brightness is calculated using, for example, the following equation 1. In Equation 1, the "upper limit transmittance" is the upper limit of the transmittance of the liquid crystal panel.

1st target brightness = (user-specified brightness ÷ upper limit transmittance) × reference brightness ... (Equation 1)

The upper limit transmittance is not particularly limited, but consider the case where the upper limit transmittance is 10 [%]. Then, consider the case where the user-specified luminance is 200 [cd / m ² ] and the reference luminance is 100 [%]. In this case, the first target luminance 2000 [cd / m ² ] can be obtained by using Equation 1. Consider a case where the upper limit transmittance is 10 [%], the user-specified luminance is 1000 [cd / m ² ], and the reference luminance is 100 [%]. In this case, the first target luminance of 10000 [cd / m ² ] can be obtained by using the formula 1. Consider a case where the upper limit transmittance is 10 [%], the user-specified luminance is 1000 [cd / m ² ], and the reference luminance is 80 [%]. In this case, the first target luminance 8000 [cd / m ² ] can be obtained by using Equation 1.

Here, consider a case where the light from the light source unit leaks to the periphery of the divided region corresponding to the light source unit. For example, when the backlight unit 3 is a direct type backlight unit, the above leakage occurs. In this case, it is preferable to determine the first target brightness in consideration of the above leakage. As a method for determining the first target luminance in consideration of the above-mentioned leakage (leakage of light (light from the light source unit) between the divided regions), various methods proposed so far can be used. For example, a method for determining the first target luminance in consideration of the above leakage is disclosed in Japanese Patent Application Laid-Open No. 2014-444302. Specific examples of the case where the method disclosed in JP-A-2014-444302 is used will be described below.

First, the first target brightness of each light source unit is set so that the first target brightness of the light source unit having a reference brightness of 100 [%] is 100 [cd / m ^{2] and the first target brightness is proportional to the reference brightness.} It will be tentatively decided. After that, for each of the plurality of divided regions, the incident luminance (luminance at the time of incident on the liquid crystal panel) of the light emitted from the backlight unit 3 (plurality of light source units) is estimated in consideration of the above leakage. Then, when there is a divided region in which the estimated incident brightness is lower than the required brightness (for example, the brightness obtained from the left side of Equation 1), the incident brightness is equal to or higher than the required brightness in all the divided regions. The first target brightness of each light source unit is increased at the same rate of increase.

In this embodiment, the estimated positions for which the incident luminance is estimated are predetermined for each of the plurality of divided regions. The estimated position is not particularly limited, but for example, for each of the plurality of divided regions, the central position of the divided region is predetermined as the estimated position. Therefore, there are a plurality of combinations of the light source unit and the estimated position. Then, the attenuation coefficient is predetermined for each of the plurality of the above combinations. The attenuation coefficient is the degree of attenuation of the light emitted from the light source unit corresponding to the attenuation coefficient until it reaches the estimated position corresponding to the attenuation coefficient.

In this embodiment, the following processing is performed for each of the plurality of estimated positions. As a result, a plurality of incident luminances corresponding to the plurality of divided regions are estimated. First, a process of multiplying the first target luminance by the attenuation coefficient corresponding to the estimated position of the processing target is performed for each light source unit. Next, the sum of the multiplication results obtained for each light source unit is calculated as the incident brightness at the estimated position of the predetermined target.

FIG. 3C shows an example of the first target luminance determined by the above method. FIG. 3C shows a case where the upper limit transmittance is 100 [%] and the user-specified luminance is 1000 [cd / m ² ]. In FIG. 3 (C), the first target luminance of 500 [cd / m], which is lower than the ^{user-specified luminance of 1000 [cd / m 2} ], with respect to the divided region in which the reference luminance is 100 [%] in FIG. 3 (B). ² ] is associated. ^{This is because light having a total brightness of 500 [cd / m 2} ] or more leaks from the periphery of the divided region. Leakage of light from the surroundings also occurs in other compartments. Therefore, in FIG. 3B, the luminance obtained by multiplying the user-specified luminance 1000 [cd / m ² ] by the reference luminance of FIG. 3B (the left side of Equation 1) also for the other divided regions. A first target brightness lower than (brightness obtained from) is associated.

The first time LPF processing unit 7 acquires the second target brightness of each light source unit by performing correction processing for each light source unit to correct the first target brightness so that the time change of the target brightness is suppressed. The second target luminance is the corrected target luminance. The degree of suppression of the time change of the target brightness is not particularly limited, but for example, the time change of the target brightness is suppressed so as to suppress the generation of flicker perceived as an obstruction by the user. The flicker considered here is, for example, a flicker caused by a sudden change in target brightness over time.

In this embodiment, the first time LPF processing unit 7 corrects the first target brightness to the second target brightness by applying the time direction LPF processing (time LPF processing) to the first target brightness. Specifically, in the display device 1, the image data of each frame of the moving image data (target moving image data) is sequentially used as the input image data. The BL luminance storage unit 8 stores a second target luminance corresponding to a frame before the current frame (current frame). In this embodiment, the BL brightness storage unit 8 stores the second target brightness corresponding to the frame immediately before the current frame (previous frame). Then, the first time LPF processing unit 7 uses the second target brightness (second target brightness corresponding to the previous frame) stored in the BL brightness storage unit 8 to notify the first target from the BL brightness determination unit 6. The brightness (first target brightness corresponding to the current frame) is corrected.

In this embodiment, the first time LPF processing unit 7 calculates the second target luminance BLC (x, y) using the following formula 2. The second target luminance BLC (x, y) is the second target luminance corresponding to the current frame, and is the second target luminance corresponding to the light source unit at the position (horizontal position, vertical position) = (x, y). .. Further, in Equation 2, "BLL (x, y)" is the first target luminance corresponding to the current frame, and is the first target luminance corresponding to the light source portion at the position (x, y). “PRBLC (x, y)” is the second target luminance corresponding to the front frame, and is the second target luminance corresponding to the light source unit at the position (x, y). Then, "α" is a time constant of the correction process for correcting the first target luminance. As the time constant α, a value larger than 0 and smaller than 1 is used. The time constant α is set by the parameter setting unit 25.

BLC (x, y) = (BLL (x, y) -PRBLC (x, y))
× (1-α) + PRBLC (x, y)
... (Equation 2)

From Equation 2, a decrease in the time constant α increases the rate of time change of the target luminance to the first target luminance, and an increase in the time constant α decreases the rate of time change of the target luminance to the first target luminance. You can see that. Specifically, it can be seen that the amount of change in the second target luminance per frame increases as the time constant α decreases, and the amount of change in the second target luminance per frame decreases as the time constant α increases. The time constant α can also be said to be the “degree of suppression of the time change of the target luminance”.

The first time LPF processing unit 7 notifies the incident brightness estimation unit 9 and the RGB-BL brightness determination unit 12 of the second target brightness of each light source unit. Further, the 1st time LPF processing unit 7 records the second target luminance of each light source unit in the BL luminance storage unit 8.

The method for correcting the first target luminance is not particularly limited. For example, as a frame before the current frame, two or more frames before the current frame may be used. Two or more frames may be used as frames prior to the current frame.

The incident brightness estimation unit 9 estimates a plurality of incident brightness corresponding to each of the plurality of estimated positions based on the second target brightness of each light source unit. Then, the incident luminance estimation unit 9 notifies the image correction value determining unit 10 of the incident luminance at each estimated position. The method for estimating the incident brightness is as described above. The shape, estimated position, etc. of the divided region are not particularly limited. In this embodiment, the shape of each divided region is a quadrangle. Then, in the present embodiment, the incident luminance estimation unit 9 estimates the positions of the four corners of each divided region, the center positions of each side of each divided region, and the plurality of positions that are the center positions of each divided region. Use as a position.

The image correction value determination unit 10 determines a correction value for correcting image data based on the estimated incident brightness for each of the plurality of estimated positions used by the incident brightness estimation unit 9. Then, the image correction value determination unit 10 outputs the correction value of each estimated position to the image correction unit 11. The display device has a need to "accurately display the brightness according to the input image data". When the incident brightness changes from a predetermined brightness, the display brightness also changes. Therefore, for example, a value that reduces the change in display brightness corresponding to the change in incident brightness from a predetermined brightness is determined as a correction value. In this embodiment, the correction coefficient Gpn, which is a gain value multiplied by the gradation value of the image data, is calculated as the correction value using the following equation 3. In Equation 3, "Lt" is the above-mentioned predetermined brightness, and "Lpn" is the estimated incident brightness. The predetermined brightness Lt is, for example, a brightness proportional to the user-specified brightness. The correction value is not limited to the gain value. For example, as a correction value, an offset value to be added to the gradation value of the image data may be determined.

Gpn = Lt / Lpn ... (Equation 3)

The image correction unit 11 corrects the input image data based on the incident brightness estimated by the incident brightness estimation unit 9. In this embodiment, the image correction unit 11 generates processed image data by correcting each gradation value of the input image data using the correction value determined by the image correction value determination unit 10. Then, the image correction unit 11 outputs the processed image data to the liquid crystal panel unit 2. Specifically, for the estimated position used by the incident luminance estimation unit 9, the correction coefficient Gpn determined by the image correction value determination unit 10 is multiplied by the gradation value of the input image data. For a position different from the estimated position used by the incident luminance estimation unit 9, the correction coefficient is determined by interpolation processing using a plurality of correction coefficients Gpn determined for a plurality of estimated positions around the position. NS. Then, the determined interpolation coefficient is multiplied by the gradation value of the input image data.

For each of the plurality of light source units, the RGB-BL brightness determination unit 12 starts with the second target brightness of the light source unit, the target brightness of the R light source unit of the light source unit, and the target brightness of the G light source unit of the light source unit. , And the target brightness of the B light source unit of the light source unit is individually determined. The "process of determining a plurality of target luminances corresponding to a plurality of color light source portions from the second target luminance of the light source portion" is "a plurality of targets corresponding to the plurality of color light source portions of the second target brightness of the light source portion". It can also be said to be "processing to divide into brightness". Then, the RGB-BL luminance determination unit 12 notifies the drive time determination unit 13 of the target luminance of each color light source unit.

In this embodiment, as the ratio for irradiating the back surface of the liquid crystal panel with white light, the emission brightness of the R light source unit: the emission brightness of the G light source unit: the emission brightness of the B light source unit = 3: 6: 1 is predetermined. ing. Then, the RGB-BL brightness determination unit 12 uses the following equations 4-1 to 4-3 for each of the plurality of light source units to obtain the target brightness of the R light source unit, the target brightness of the G light source unit, and B. Calculate the target brightness of the light source unit. When the target brightness of the light source unit is 500 [cd / m ² ], the target brightness of the R light source unit is 150 [cd / m ² ] and the target brightness of the G light source unit is set by using equations 4-1 to 4-3. A brightness of 300 [cd / m ² ] and a target brightness of 50 [cd / m ² ] of the B light source unit are calculated. The ratio is not limited to 3: 6: 1.

Target brightness of R light source unit = 2nd target brightness of light source unit x 3 ÷ (3 + 6 + 1)
... (Equation 4-1)
Target brightness of G light source unit = 2nd target brightness of light source unit x 6 ÷ (3 + 6 + 1)
... (Equation 4-2)
B Target brightness of the light source unit = Second target brightness of the light source unit x 1 ÷ (3 + 6 + 1)
... (Equation 4-3)

The drive time determination unit 13 performs a drive value determination process for each color light source unit. The drive value determination process for the color light source unit is "a process of determining a drive value which is a value for controlling the emission brightness of the color light source unit to the target brightness based on the target brightness of the color light source unit". Therefore, the drive value determination process for the light source unit (combination of a plurality of drive value determination processes corresponding to each of the plurality of color light source units belonging to the light source unit) is "light emission of the light source unit based on the second target brightness of the light source unit. It can be said to be "a process of determining a drive value which is a value for controlling the brightness to the second target brightness". The drive time determination unit 13 notifies the total drive time determination unit 14 and the drive time correction unit 17 of the determined drive value (first drive value; uncorrected drive value).

In this embodiment, each color light source unit is driven by a pulse width modulation method. Therefore, a value related to the drive time of the color light source unit is used as the drive value. In this case, the drive value determination process can be said to be "process for determining the drive time". The drive method of the color light source unit is not limited to the pulse width modulation method. For example, the color light source unit may be driven by a pulse amplitude modulation method, a method combining a pulse width modulation method and a pulse amplitude modulation method, or the like. When the color light source unit is driven by the pulse amplitude modulation method, a value related to the current value supplied to the color light source unit is used as the drive value. When the color light source unit is driven by a method that combines the pulse width modulation method and the pulse amplitude modulation method, a value related to the drive time and the current value supplied to the color light source unit is used as the drive value. ..

In this embodiment, the drive time determination unit 13 determines the uncorrected drive value of each color light source unit in consideration of the luminous efficiency of each color light source unit. Specifically, as the drive value determination process, "a process of determining the uncorrected drive value of the color light source unit based on the following three elements 1 to 3" is performed.

Element 1: Target brightness of the color light source unit Element 2: Correspondence between the luminous brightness of the color light source unit and the uncorrected drive value of the color light source unit when the luminous efficiency of the color light source unit is the standard luminous efficiency Element 3: Difference between the luminous efficiency of the color light source and the standard luminous efficiency

"The correspondence between the luminous brightness of the color light source unit and the uncorrected drive value of the color light source unit when the luminous efficiency of the color light source unit is the standard luminous efficiency" is "emission based on the luminous efficiency of the color light source unit". It can also be said that there is a correspondence between the luminous brightness of the color light source unit and the driving time of the color light source unit in the case of efficiency. This correspondence is not particularly limited, but in this embodiment, the correspondence of FIG. 4 is used. The horizontal axis of FIG. 4 indicates the emission brightness of the color light source unit, and the vertical axis of FIG. 4 indicates the driving time of the color light source unit. The thick solid line in FIG. 4 shows the correspondence when the luminous efficiency of the color light source unit is the reference luminous efficiency. The drive time value in FIG. 4 is a standardized value. The drive time of 100 [%] corresponds to a state in which the color light source unit continues to light for a period of one frame. Actually, a reset period of the light source driver (control circuit that controls the light emission of each light source) is required. Therefore, when the length of the period of one frame is 16.6 [msec], the drive time of 100 [%] corresponds to the time of 16.6 [msec] or less.

As the "difference between the luminous efficiency of the color light source unit and the reference luminous efficiency", the following three differences 1 to 3 may exist. In this embodiment, all of the differences 1-3 are considered. It should be noted that one or two of the differences 1 to 3 may not be considered. For example, only the difference 1 may be considered, or only the differences 2 and 3 may be considered.

Difference 1: Difference caused during the manufacture of the color light source part Difference 2: Difference caused by the temperature change of the color light source part Difference 3: Difference caused by the aging deterioration of the color light source part

In this embodiment, the first correction value Ch (c, x, y) for reducing the brightness change (change in emission brightness from the target brightness) due to the difference 1 is recorded in advance in the first correction value storage unit 22. Has been done. The first correction value Ch (c, x, y) is a correction value of the color light source unit that belongs to the light source unit at the position (x, y) and whose emission color is color c. Further, in this embodiment, the second correction value Cd (c, x, y) for reducing the brightness change (change in emission brightness from the target brightness) caused by the above differences 2 and 3 is the second correction value determination unit. Determined by 21. The second correction value Cd (c, x, y) is a correction value of the color light source unit that belongs to the light source unit at the position (x, y) and whose emission color is the color c.

In this embodiment, the drive time determination unit 13 determines the target luminance L (c, of the color light source unit) of the color light source unit from the correspondence relationship of FIG. The drive time Dr (c, x, y) = f (L (c, x, y)) corresponding to x, y) is acquired. Further, the drive time determination unit 13 acquires the first correction value Ch (c, x, y) from the first correction value storage unit 22, and obtains the second correction value Cd (c, x, y) as the second correction value. Obtained from the determination unit 21. Then, the drive time determination unit 13 uses the following equation 5 to drive the drive time Dr (c, x, y), the first correction value Ch (c, x, y), and the second correction value Cd (c). , X, y), the drive time RDr (c, x, y) of the color light source unit is calculated. In this embodiment, the drive time determination unit 13 notifies the drive time RDr (c, x, y) as an uncorrected drive value.

RDr (c, x, y)
= Dr (c, x, y) x Ch (c, x, y) x Cd (c, x, y)
... (Equation 5)

Such processing is performed individually for each color light source unit. Hereinafter, the drive time RDr (c, x, y) of the R light source unit belonging to the light source unit at the position (x, y) will be referred to as “drive time RDrr (x, y)”. The drive time RDr (c, x, y) of the G light source unit belonging to the light source unit at the position (x, y) is described as "drive time RDrg (x, y)". Then, the drive time RDr (c, x, y) of the B light source unit belonging to the light source unit at the position (x, y) is described as "drive time RDrb (x, y)".

A value different from the drive time value may be used as the drive value. For example, as the drive value, another value proportional to the drive time may be used. Specifically, when the color light source unit is driven by the pulse width modulation method, a value proportional to the drive time is used as a control value for controlling the processing of the light source driver. In such a case, the control value of the light source driver may be used as the drive value.

The total drive time determination unit 14 determines the total drive time based on the uncorrected drive value of each color light source unit, and notifies the time correction value determination unit 15 of the determined total drive time. In this embodiment, the total drive time is the sum of the plurality of drive times corresponding to the plurality of color light source units having the same emission color. Further, in the present embodiment, the total drive time determination unit 14 determines the total drive time for each of the plurality of emission colors. Specifically, the total drive time determination unit 14 determines the total drive time, which is the sum of the plurality of drive times corresponding to the plurality of R light source units, based on the uncorrected drive values of each R light source unit. The total drive time determination unit 14 determines the total drive time, which is the sum of the plurality of drive times corresponding to the plurality of G light source units, based on the uncorrected drive values of each G light source unit. Then, the total drive time determination unit 14 determines the total drive time, which is the sum of the plurality of drive times corresponding to the plurality of B light source units, based on the uncorrected drive values of each B light source unit.

The time correction value determination unit 15 determines a time correction value for correcting the uncorrected drive value of each color light source unit, and notifies the time correction value selection unit 16 of the determined time correction value. The time correction value can also be said to be a "correction value for correcting the driving time". Specifically, the time correction value determination unit 15 compares the total drive time determined by the total drive time determination unit 14 with the threshold value, and determines the time correction value based on the comparison result in a plurality of emission colors. Do for each of. In this embodiment, for the emission color whose total driving time is longer than the threshold value, a time correction value that limits the total driving time to the threshold value or less is determined. A specific example of the processing of the time correction value determination unit 15 will be described below.

The amount of current IR (x, y) supplied to the R light source unit, the amount of current IG (x, y) supplied to the G light source unit, and the amount of current IB (x, y) supplied to the B light source unit are , Can be expressed by the following equations 6-1 to 6-3. In formulas 6-1 to 6-3, "Ir" is the time average of the amount of current supplied to the R light source unit, and "Ig" is the time average of the amount of current supplied to the G light source unit. “Ib” is the time average of the amount of current supplied to the B light source unit. The "time average of the amount of current supplied to the color light source unit" is, for example, "the time average of the amount of current supplied to the color light source unit during the period when the color light source unit continues to light". be.

IR (x, y) = Ir × RDrr (x, y) ... (Equation 6-1)
IG (x, y) = Ig x RDrg (x, y) ... (Equation 6-2)
IB (x, y) = Ib x RDrb (x, y) ... (Equation 6-3)

Then, the total SR of the current amount IR (x, y) supplied to each R light source unit, the total SG of the current amount IG (x, y) supplied to each G light source unit, and the total B light source unit are supplied. The total SB of the amount of current IB (x, y) to be generated can be expressed by the following equations 7-1 to 7-3.

SR = ΣIR (x, y)
= Σ (Ir × RDrr (x, y))
= Ir × ΣRDrr (x, y)
... (Equation 7-1)
SG = ΣIG (x, y)
= Σ (Ig × RDrg (x, y))
= Ig x ΣRDrg (x, y)
... (Equation 7-2)
SB = ΣIB (x, y)
= Σ (Ib x RDrb (x, y))
= Ib × ΣRDrb (x, y)
... (Equation 7-3)

ΣRDrr (x, y) in Equation 7-1 is the total drive time of the plurality of R light source units, and ΣRDrg (x, y) in Equation 7-2 is the total drive time of the plurality of G light source units. ΣRDrb (x, y) of -3 is the total drive time of the plurality of B light source units. Therefore, the threshold values ΣRDrr (x, y) max, ΣRDrg (x, y) max, and ΣRDrb (x, y) max to be compared with the total drive time can be obtained by the following equations 8-1 to 8-3. .. In equations 8-1 to 8-3, "SRmax" is the upper limit of the total amount of current supplied to each R light source unit, and "SGmax" is the total amount of current supplied to each G light source unit. It is an upper limit, and "SBmax" is an upper limit of the total amount of current supplied to each B light source unit. “ΣRDrr (x, y) max” is a threshold value to be compared with the total drive time of a plurality of R light source units. “ΣRDrg (x, y) max” is a threshold value to be compared with the total drive time of a plurality of G light source units. Then, "ΣRDrb (x, y) max" is a threshold value to be compared with the total drive time of the plurality of R light source units.

ΣRDrr (x, y) max = SRmax / Ir ... (Equation 8-1)
ΣRDrg (x, y) max = SGmax / Ig ... (Equation 8-2)
ΣRDrb (x, y) max = SBmax / Ib ... (Equation 8-3)

The current amounts SRmax, SGmax, and SBmax are determined according to the performance of the power supply that supplies power to the display device 1, the performance of the display device 1 (such as the power supply circuit of the display device 1), and the like. Therefore, it can be said that "thresholds ΣRDrr (x, y) max, ΣRDrg (x, y) max, ΣRDrb (x, y) max are determined by the above performance and the like".

Even if the upper limit of the amount of current that can be output by the power supply is the same among the plurality of emission colors, the voltage applied to the color light source unit is generally different among the plurality of emission colors. Further, in general, the electric power required for the color light source unit for irradiating the back surface of the liquid crystal panel with white light also differs among the plurality of emitted colors. Therefore, in general, the current amount SRmax, the current amount SGmax, and the current amount SGmax are different from each other, and the threshold value ΣRDrr (x, y) max, the threshold value ΣRDrg (x, y) max, the threshold value, and the ΣRDrb (x, y) max. Are different from each other.

According to Equations 8-1 to 8-3, the upper limit of the total driving time is obtained as a threshold value. However, a time different from the upper limit of the total drive time may be used as the threshold value. For example, a time shorter than the upper limit of the total drive time may be used as the threshold value. Further, a common threshold value may be used among a plurality of emission colors.

In this embodiment, the time correction value determination unit 15 calculates the time correction values GainR, GainG, and GainB using the following equations 9-1 to 9-3. According to Equations 9-1 to 9-3, the time correction values GainR, GainG, and GainB are calculated by dividing the threshold value by the total drive time. Therefore, the time correction values GainR, GainG, and GainB are the ratios of the threshold values to the total drive time.

GainR = ΣRDrr (x, y) max / ΣRDrr (x, y)
... (Equation 9-1)
GainG = ΣRDrg (x, y) max / ΣRDrg (x, y)
... (Equation 9-2)
GainB = ΣRDrb (x, y) max / ΣRDrb (x, y)
... (Equation 9-3)

The time correction value GainR is a time correction value for correcting the uncorrected drive value (drive time) of each R light source unit. The time correction value GainG is a time correction value for correcting the uncorrected drive value of each G light source unit. The time correction value GainB is a time correction value for correcting the uncorrected drive value of each B light source unit. Specifically, the time correction value GainR is a gain value multiplied by the uncorrected drive value of each R light source unit. The time correction value GainG is a gain value that is multiplied by the uncorrected drive value of each G light source unit. The time correction value Gain B is a gain value that is multiplied by the uncorrected drive value of each B light source unit. The total drive time can be limited to the threshold value by multiplying each uncorrected drive value by the time correction value for the emission color whose total drive time is longer than the threshold value.

The time correction value determination unit 15 outputs the time correction values GainR, GainG, and GainB calculated using the equations 9-1 to 9-3. However, when ΣRDrr (x, y) ≦ ΣRDrr (x, y) max, the time correction value determining unit 15 outputs the time correction value GainR = 1. When ΣRDrg (x, y) ≦ ΣRDrg (x, y) max, the time correction value determining unit 15 outputs the time correction value GainG = 1. Then, in the case of ΣRDrb (x, y) ≦ ΣRDrb (x, y) max, the time correction value determining unit 15 outputs the time correction value GainB = 1.

The time correction value is not limited to the above value. A value different from the ratio of the threshold value to the total drive time may be determined as the time correction value. A time correction value that limits the total drive time to a time shorter than the threshold value may be determined. The offset value added to each uncorrected drive value may be determined as the time correction value.

The time correction value selection unit 16 selects any one of the time correction value GainR, the time correction value GainG, and the time correction value GainB. The selected time correction value is used for correction of each uncorrected drive value (uncorrected drive value of each R light source unit, uncorrected drive value of each G light source unit, and uncorrected drive value of each B light source unit). Will be done. In this embodiment, the time correction value selection unit 16 selects the minimum values of the time correction value GainR, the time correction value GainG, and the time correction value GainB. Then, the time correction value selection unit 16 notifies the drive time correction unit 17 of the selected time correction value.

When correction using different time correction values is performed among a plurality of emission colors, the ratio (emission brightness of R light source unit: emission brightness of G light source unit: B light source unit) is obtained by correcting each uncorrected drive value. Luminance brightness) may change from the ratio for irradiating the back surface of the liquid crystal panel with white light. By selecting any one of the time correction value GainR, the time correction value GainG, and the time correction value GainB and using it for the correction, such a change in the ratio can be suppressed. Further, when correction is performed using a time correction value larger than the minimum values of the time correction value GainR, the time correction value GainG, and the time correction value GainB, even if each uncorrected drive value is corrected, the total is totaled. The emission color that has a driving time longer than the threshold value may remain. By selecting the minimum values of the time correction value GainR, the time correction value GainG, and the time correction value GainB and using them for the correction, the total drive time of each emission color can be surely limited to the threshold value or less.

The time correction value selection method (determination method) used for correction of each uncorrected drive value is not limited to the above method. For example, the time correction value selection unit 16 may select the maximum values of the time correction value GainR, the time correction value GainG, and the time correction value GainB as the time correction values used for the correction of each uncorrected drive value. .. The time correction value selection unit 16 selects the second largest value among the time correction value GainR, the time correction value GainG, and the time correction value GainB as the time correction value used for the correction of each uncorrected drive value. You may. The time correction value selection unit 16 sets the time correction value GainR, the time correction value GainG, and the time correction value GainB as other representative values (average value, intermediate value) as the time correction value used for the correction of each uncorrected drive value. , Mode, etc.) may be determined. The time correction value selection unit 16 may select the time correction value GainR as the time correction value used for correcting the uncorrected drive value of each R light source unit. The time correction value selection unit 16 may select the time correction value GainG as the time correction value used for correcting the uncorrected drive value of each G light source unit. The time correction value selection unit 16 may select the time correction value GainB as the time correction value used for correcting the uncorrected drive value of each B light source unit.

The drive time correction unit 17 corrects each uncorrected drive value notified from the drive time determination unit 13 by using the time correction value notified from the time correction value selection unit 16. In this embodiment, the drive time correction unit 17 multiplies the time correction value notified by the time correction value selection unit 16 by each uncorrected drive value notified by the drive time determination unit 13. As a result, each uncorrected drive value notified from the drive time determination unit 13 is corrected, and the first corrected drive value (third drive value; the drive value after correction by the drive time correction unit 17) of each color light source unit is obtained. Be done. Then, the drive time correction unit 17 outputs each first correction drive value to the second time LPF processing unit 18.

The time correction value determination unit 15 may determine the time correction value only for the emission color whose total drive time determined by the total drive time determination unit 14 is longer than the threshold value. Then, the drive time correction unit 17 may omit the correction of each uncorrected drive value when there is no emission color whose total drive time is longer than the threshold value.

The second time LPF processing unit 18 performs correction processing for each color light source unit to correct the first correction drive value so that the time change of the drive value is suppressed, so that the second correction drive value (second correction drive value) of each color light source unit is performed. 2 Drive value; drive value after correction processing) is acquired. The degree of suppression of the time change of the drive value is not particularly limited, but for example, the time change of the drive value is suppressed so as to suppress the occurrence of flicker perceived as an interference by the user. The flicker considered here is, for example, a flicker caused by a correction that limits the total drive time (power required for the display device 1) to a threshold value or less.

In this embodiment, the second time LPF processing unit 18 corrects the first correction drive value to the second correction drive value by applying the time LPF process to the first correction drive value. Specifically, the drive time storage unit 19 stores the second correction drive value corresponding to the frame before the current frame. In this embodiment, the drive time storage unit 19 stores the second correction drive value corresponding to the previous frame. Then, the second time LPF processing unit 18 corrects the first correction drive value notified from the drive time correction unit 17 by using the second correction drive value stored in the drive time storage unit 19. By using the past second correction drive value, the first correction drive value can be corrected so that the total drive time does not exceed the threshold value.

In this embodiment, the second time LPF processing unit 18 calculates the second correction drive value (drive time) PWM (x, y) using the following equation 10. The second correction drive value PWM (x, y) is the second correction drive value corresponding to the current frame, and is the second correction drive value corresponding to the light source unit at the position (x, y). Further, in the equation 10, "cPWM (x, y)" is the first correction drive value (drive time) corresponding to the current frame, and the first correction drive value corresponding to the light source unit at the position (x, y). Is. “PRPWM (x, y)” is a second correction drive value (drive time) corresponding to the previous frame, and is a second correction drive value corresponding to the light source unit at the position (x, y). Then, "β" is a time constant of the correction process for correcting the first correction drive value. As the time constant β, a value of 0 or more and less than 1 is used. The time constant β is set by the parameter setting unit 25.

BLC (x, y) = (BLL (x, y) -PRBLC (x, y))
× (1-α) + PRBLC (x, y)
... (Equation 10)

From Equation 10, as the time constant β decreases, the speed of time change of the drive value to the first correction drive value increases, and as the time constant β increases, the speed of time change of the drive value to the first correction drive value increases. It can be seen that it decreases. Specifically, a decrease in the time constant β may increase the amount of change in the second correction drive value per frame, and an increase in the time constant β may decrease the amount of change in the second correction drive value per frame. Understand. The time constant β can also be said to be the “degree of suppression of the time change of the drive value”.

The second time LPF processing unit 18 outputs the second correction drive value of each color light source unit to the backlight unit 3. As a result, each color light source unit of the backlight unit 3 emits light according to the second correction drive value. Further, the second time LPF processing unit 18 records the second correction drive value of each color light source unit in the drive time storage unit 19.

The method of correcting the first correction drive value is not particularly limited. For example, as a frame before the current frame, two or more frames before the current frame may be used. Two or more frames may be used as frames prior to the current frame. Further, the processing of the drive time correction unit 17 may be omitted, and the uncorrected drive value may be corrected so that the time change of the drive value is suppressed.

The BL brightness detection unit 20 is a brightness sensor that detects the brightness (luminance distribution; emission brightness of each light source unit) of the light emitted from the backlight unit 3. The BL brightness detection unit 20 notifies the second correction value determination unit 21 of the detection result of the brightness of the light from the backlight unit 3. In this embodiment, the BL luminance detection unit 20 detects the luminance for each of the plurality of emission colors. That is, the BL brightness detection unit 20 detects the emission brightness of each color light source unit. The brightness detection of the BL brightness detection unit 20 is performed to detect a change in the luminous efficiency of each color light source unit. Therefore, the brightness detection of the BL brightness detection unit 20 is performed under the same driving conditions (driving time) of each color light source unit. The method of detecting the brightness is not particularly limited as long as the brightness corresponding to a predetermined driving condition can be detected. For example, a time-integrated value may be obtained as the detected value of the brightness, and the brightness corresponding to the unit time may be obtained from the obtained detected value.

The second correction value determination unit 21 determines the second correction value based on the detection result from the BL brightness detection unit 20, and notifies the drive time determination unit 13 of the determined second correction value. For example, the second correction value determination unit 21 stores in advance the value of the brightness (initial brightness) corresponding to the reference luminous efficiency. Then, the second correction value determination unit 21 compares the detected brightness with the initial brightness, and based on the comparison result, corrects the drive time so that the detected brightness approaches the initial brightness. The process of determining is performed for each color light source unit. Specifically, when the detected brightness is 5 [%] lower than the initial brightness, the second correction value for extending the drive time by 5 [%] is determined.

The user I / F unit 23 is an interface (reception unit) capable of receiving a request from a user. When the user performs an operation on the display device 1, the user I / F unit 23 determines the request corresponding to the operation as a request from the user. Then, the user I / F unit 23 outputs the information corresponding to the request to the parameter setting unit 25. For example, when the user presses a button provided on the display device 1, a menu image is displayed on the screen. Then, when the user selects any of the plurality of items included in the menu image, the user I / F unit 23 outputs the information corresponding to the selected item to the parameter setting unit 25. The type of operation, the type of request, etc. are not particularly limited. In this embodiment, the user makes a request regarding the user-specified luminance, a request regarding the LUT used by the BL reference luminance determining unit 5, a request regarding the contrast of the displayed image, and the like.

The scene change detection unit 24 detects a scene change of the target moving image data. Specifically, the scene change detection unit 24 determines whether or not the scene has been switched between the previous frame and the current frame. In this embodiment, the scene change detection unit 24 detects a scene change (scene change) based on the feature amount acquired by the feature amount acquisition unit 4. For example, the scene change detection unit 24 counts the number of division regions (change regions) in which the magnitude of change in the feature amount between the previous frame and the current frame is equal to or greater than a predetermined value. Then, when the number of change regions is equal to or greater than a predetermined number, the scene change detection unit 24 determines that "the scene has been switched between the previous frame and the current frame". When the number of change regions is less than a predetermined number, the scene change detection unit 24 determines that "the scene has not been switched between the previous frame and the current frame". The scene change detection unit 24 notifies the parameter setting unit 25 of the scene change detection result.

The method of detecting the change of the scene is not particularly limited. For example, when the metadata added to the target moving image data includes information about the scene (scene information), the scene switching may be detected by using the scene information.

The parameter setting unit 25 gives instructions to each function unit of the display device 1, sets parameters to each function unit, and the like. For example, when there is a request regarding the user-specified brightness, the parameter setting unit 25 determines the user-specified brightness corresponding to the request from the user according to the information from the user I / F unit 23, and the BL brightness determination unit 6. Set for. When there is a request regarding the LUT used by the BL reference luminance determination unit 5, the parameter setting unit 25 sets the LUT corresponding to the request from the user according to the information from the user I / F unit 23. It is set for the reference brightness determining unit 5. Alternatively, the parameter setting unit 25 instructs the BL reference luminance determination unit 5 to change the LUT to the LUT corresponding to the request from the user according to the information from the user I / F unit 23. The "requirement regarding the LUT used in the BL reference luminance determination unit 5" may be the "requirement regarding the contrast of the displayed image".

Further, the parameter setting unit 25 includes parameters used in the correction processing (time LPF processing) of the first time LPF processing unit 7 and parameters used in the correction processing (time LPF processing) of the second time LPF processing unit 18. And set. In this embodiment, the parameter setting unit 25 sets the time constants α and β.

When the time constant β used in the time LPF processing of the second time LPF processing unit 18 increases, the time change of the driving value (driving time) is reduced, and the second target brightness of each light source unit (target after the time LPF processing). Brightness) and the actual emission brightness of each light source unit increase. As a specific example of this, an example will be described in which the input image data of the previous frame is the image data of FIG. 5 (A) and the input image data of the current frame is the image data of FIG. 5 (B).

In the examples of FIGS. 5A and 5B, two objects (quadrilateral objects) that do not exist in the previous frame appear in the current frame. The brightness of the two objects that appear is high. Therefore, the emission brightness of the light source unit may increase in the divided region including at least a part of the appearing object. Then, as the emission brightness of the light source unit increases, the power consumption of the backlight unit 3 also increases.

FIG. 6A shows the distribution of the first target luminance (first target luminance of the previous frame; the target luminance determined by the BL luminance determination unit 6) on the broken line X of FIG. 5 (A). FIG. 6B shows the distribution of the first target luminance (first target luminance of the current frame) on the broken line X of FIG. 5B. The position and orientation of the broken line X in FIG. 5 (A) are the same as those of the broken line X in FIG. 5 (B). The horizontal axis of FIGS. 6 (A) and 6 (B) indicates the horizontal position of the divided region, and the vertical axis of FIGS. 6 (A) and 6 (B) indicates the first target luminance. In the examples of FIGS. 6 (A) and 6 (B), among the 10 divided regions through which the broken line X passes, the first target luminance of the three divided regions at the horizontal positions x = 8, 9, and 10 is high brightness. It is increasing due to the appearance of objects. The "first target luminance of the divided region" is the "first target luminance determined for the light source unit corresponding to the divided region".

FIG. 6C shows a second target luminance obtained from the first target luminance of FIG. 6B by the first time LPF processing unit 7 (second target luminance of the current frame; target luminance after the time LPF processing). The distribution of is shown. The horizontal axis of FIG. 6 (C) indicates the horizontal position of the divided region, and the vertical axis of FIG. 6 (C) indicates the second target luminance. FIG. 6C shows an example in which the same brightness as the first target brightness of FIG. 6A is obtained as the second target brightness of the front frame. In the example of FIG. 6 (C), the first target luminance of FIG. 6 (A) and the first target luminance of FIG. 6 (B) are set as the second target luminance of the three divided regions of the horizontal positions x = 8, 9 and 10 by the time LPF processing. ) Is obtained. When the time constant α of the time LPF processing of the first time LPF processing unit 7 is large, the speed of time change of the target brightness is slow, and the second target brightness close to the first target brightness of FIG. 6A can be obtained. .. When the time constant α of the time LPF processing of the first time LPF processing unit 7 is small, the speed of time change of the target brightness is high, and the second target brightness close to the first target brightness of FIG. 6B can be obtained. ..

FIG. 7A shows the distribution of the uncorrected drive value (the uncorrected drive value of the previous frame; the drive value determined by the drive time determination unit 13) on the broken line X of FIG. 5 (A). FIG. 7 (B) shows the distribution of the uncorrected drive value (the uncorrected drive value of the current frame) on the broken line X of FIG. 5 (B). The horizontal axis of FIGS. 7 (A) and 7 (B) indicates the horizontal position of the divided region, and the vertical axis of FIGS. 7 (A) and 7 (B) indicates the uncorrected drive value (drive time). FIG. 7 (A) shows an example in which the same brightness as the first target brightness of FIG. 6 (A) is obtained as the second target brightness of the front frame. The uncorrected drive value in FIG. 7B is a value obtained from the second target luminance in FIG. 6C. The luminous efficiency of the light source unit is not uniform among the plurality of divided regions. Therefore, even if the second target brightness is the same between the previous frame and the current frame, the uncorrected drive value is different between the previous frame and the current frame. For example, in the divided region of the horizontal position x = 2 to 7, the second target luminance is the same between the previous frame and the current frame, but the uncorrected drive value is different between the previous frame and the current frame.

FIG. 8 (A) shows the distribution of the first corrected drive value (first corrected drive value of the current frame) obtained from the uncorrected drive value of FIG. 7 (B) by the drive time correction unit 17. The horizontal axis of FIG. 8A indicates the horizontal position of the divided region, and the vertical axis of FIG. 8A indicates the first correction drive value. In the example of FIG. 8A, a value smaller than the uncorrected driving value of FIG. 7B is obtained as the first corrected driving value. FIG. 8B shows the distribution of the second correction drive value (second correction drive value of the current frame) obtained from the first correction drive value of FIG. 8A by the second time LPF processing unit 18. The horizontal axis of FIG. 8B indicates the horizontal position of the divided region, and the vertical axis of FIG. 8B indicates the second correction drive value. FIG. 8B shows an example in which the same drive value as the uncorrected drive value of FIG. 7A is obtained as the second correction drive value of the front frame. In the divided region of the horizontal position x = 1 to 7, the uncorrected drive value in FIG. 7 (A) is larger than the first corrected drive value in FIG. 8 (A). Therefore, in the example of FIG. 8B, a drive value larger than the first correction drive value of FIG. 8A is obtained as the second correction drive value of the divided region of the horizontal position x = 1 to 7. .. On the other hand, in the divided region of the horizontal position x = 8 to 10, the uncorrected drive value in FIG. 7 (A) is smaller than the first corrected drive value in FIG. 8 (A). Therefore, in the example of FIG. 8B, a drive value smaller than the first correction drive value of FIG. 8A is obtained as the second correction drive value of the divided region of the horizontal position x = 8 to 10. ..

FIG. 9 shows the actual distribution of the emission brightness of the light source unit. FIG. 9 shows the emission brightness (emission brightness of the current frame) on the broken line X of FIG. 5 (B). The horizontal axis of FIG. 9 indicates the horizontal position of the divided region, and the vertical axis of FIG. 9 indicates the actual emission brightness. The emission brightness in FIG. 9 is the brightness obtained from the second correction drive value in FIG. 8 (B). In FIG. 9, as the emission brightness, a brightness different from the second target brightness of FIG. 6C is obtained. Further, the ratio of the brightness of the divided region at the horizontal position x = 2 to 7 and the brightness of the divided region at the horizontal positions 8 to 9 is different between FIGS. 9 and 6 (C). As described above, the time LPF processing of the second time LPF processing unit 18 causes a difference between the second target brightness of each light source unit and the actual emission brightness of each light source unit.

Then, when the ratio of the emission luminance between the light source portions changes, the shape of the incident luminance distribution changes. Therefore, when the ratio of the second target brightness between the light source units is different from the ratio of the actual emission brightness between the light source units, the shape of the estimated incident brightness distribution is different from the shape of the actual incident brightness distribution. It ends up. If the shape of the estimated incident luminance distribution is different from the shape of the actual incident luminance distribution, the change in display luminance due to the change in incident luminance cannot be reduced by image processing (processing of the image correction unit 11), and the input image. The brightness of the data cannot be displayed faithfully. The image quality of the displayed image may be deteriorated to a lower image quality than the image quality when the processing of the image correction unit 11 is not performed.

Therefore, in this embodiment, the parameter setting unit 25 uses the second target brightness of each light source unit (the shape of the second target brightness of each light source unit) and the actual emission brightness of each light source unit (actual emission brightness of each light source unit). The time constants α and β are set so that the difference from the emission brightness shape) is equal to or less than the threshold value. Therefore, when one of the time constant α and the time constant β is changed, the parameter setting unit 25 makes the difference between the second target brightness of each light source unit and the actual emission brightness of each light source unit equal to or less than the threshold value. In addition, the other of the time constant α and the time constant β is also changed.

As a result, deterioration of the image quality of the displayed image can be suppressed with high accuracy by a simple configuration in which the time constant α and the time constant β are set so that the time constant α and the time constant β are interlocked with each other. Specifically, the incident brightness can be estimated with high accuracy, and the input image data can be corrected with high accuracy. As a result, deterioration of image quality due to a change in incident brightness can be suppressed with high accuracy. Further, since the values capable of suppressing the occurrence of conspicuous flicker are set as the time constants α and β, it is possible to obtain a high-quality display image in which the occurrence of flicker is suppressed.

The threshold value to be compared with the difference between the second target brightness and the actual emission brightness is determined in consideration of, for example, the accuracy of estimating the incident brightness. The threshold value may be a fixed value predetermined by the manufacturer or a value that can be changed by the user. The threshold value may be automatically determined according to the usage environment of the display device 1, the type of input image data, and the like.

By increasing the rate of time change of the drive value to the unprocessed drive value, it is possible to reduce the difference between the second target brightness of each light source unit and the actual emission brightness of each light source unit. However, conspicuous flicker is generated only by increasing the speed of time change of the drive value to the unprocessed drive value. Therefore, in the present embodiment, the parameter setting unit 25 uses the time constant α, so that the time change of the drive value to the unprocessed drive value is performed at a speed faster than the time change of the target brightness to the first target brightness. Set β. Specifically, the parameter setting unit 25 sets a value smaller than the time constant α as the time constant β. Thereby, the above effect can be obtained.

The parameter setting unit 25 may set parameters different from the time constants α and β as the parameters used in the time LPF processing. The parameter setting unit 25 may set the time constants α and β and other parameters as the parameters used in the time LPF processing. The parameters used in the time LPF processing are not particularly limited. Further, as long as the difference between the second target brightness of each light source unit and the actual emission brightness of each light source unit is equal to or less than the threshold value, the specific value of the parameter used in the time LPF processing is not particularly limited. Further, the method of setting or changing the parameters used in the time LPF processing is not particularly limited.

A specific example of how to set the time constants α and β will be described with reference to FIG. The time constants α and β shown in FIG. 10 are examples, and values different from the values in FIG. 10 may be set as the time constants α and β.

(Setting method 1)
The setting method 1 is a method of setting the values as the time constants α and β in response to a request from the user. Here, the "requirement" is, for example, a "requirement regarding the contrast of the displayed image". The requirements regarding the contrast of the displayed image are, for example, a request for setting the "high contrast mode" of FIG. 10, a request for setting the "low contrast mode" of FIG. 10, and the like. Whether or not there is a request is determined using the information from the user I / F unit 23.

The high contrast mode is a display mode that realizes a display image having a higher contrast than the low contrast mode. The contrast corresponding to the high contrast mode is not particularly limited, but for example, the upper limit of the display brightness: the lower limit of the display brightness = 5000: 1. The low contrast mode is a display mode that realizes a display image having a lower contrast than the high contrast mode. The contrast corresponding to the low contrast mode is not particularly limited, but for example, the upper limit of the display brightness: the lower limit of the display brightness = 2500: 1.

In the example of FIG. 10, when there is a request to set the low contrast mode, “0.80” is set as the time constant α, and “0.” which is smaller than “0.80” as the time constant β. 60 "is set. In the high contrast mode, the difference between the upper limit of the emission brightness of the light source unit and the lower limit of the emission brightness of the light source unit is larger than that in the low contrast mode. Therefore, when the time constants α and β are constant, in the high contrast mode, the fluctuation range of the emission brightness of the light source unit is larger than in the low contrast mode, and flicker is more noticeable than in the low contrast mode. In order to suppress the occurrence of conspicuous flicker, in the example of FIG. 10, when there is a request to set the high contrast mode, the time constant α is set to "0.80" corresponding to the low contrast mode. Also large "0.90" is set. Similarly, as the time constant β, “0.70”, which is larger than “0.60” corresponding to the low contrast mode, is set.

The request from the user is not particularly limited. For example, the request from the user may be a request regarding the current value supplied to the backlight unit 3 (each color light source unit). Specifically, the request from the user is to set a display mode in which the current value supplied to the backlight unit 3 is high, and to set a display mode in which the current value supplied to the backlight unit 3 is low. It may be a request of. When the value of the current supplied to the backlight unit 3 changes, the threshold value of the total drive time also changes. Specifically, the higher the current value supplied to the backlight unit 3, the smaller (shorter) the threshold value of the total drive time. Therefore, in order to prevent the total drive time from exceeding the threshold value, when there is a request for a high current value, a time constant β smaller than the time constant β when there is a request for a low current value is set. Is preferable. Further, in order to surely prevent the total drive time from exceeding the threshold value, it is preferable that the time constant β = 0 is set when there is a request for a very large current value.

(Setting method 2)
The setting method 2 is a method in consideration of switching of the display mode of the display device 1. The switching of the display mode is, for example, switching from one of the high-contrast mode and the low-contrast mode to the other of the high-contrast mode and the low-contrast mode. The plurality of display modes included in the display device 1 may include display modes different from the high-contrast mode and the low-contrast mode. The display mode before switching may be different from the high contrast mode and the low contrast mode. Similarly, the display mode after switching may be different from the high contrast mode and the low contrast mode.

At the timing of switching the display mode, there is a high possibility that the flicker will not be noticeable, the user will tolerate the flicker, and the like. Therefore, the parameter setting unit 25 sets small values (initial values) as the time constants α and β when the display mode is switched, and gradually increases the time constants α and β from the initial values to the target values. .. In the example of FIG. 10, the parameter setting unit 25 sets “0.20” as the time constant α when the display mode is switched, and sets “0.20” as the time constant β, which is smaller than “0.20”. 10 ”is set. The target values of the time constants α and β are not particularly limited, but for example, a value corresponding to the set display mode is used as the target value. Specifically, when the high contrast mode is set, "0.90" is used as the target value of the time constant α, and "0.70" is used as the target value of the time constant β. When the low contrast mode is set, "0.80" is used as the target value of the time constant α, and "0.60" is used as the target value of the time constant β.

(Setting method 3)
The setting method 3 is a method in consideration of switching scenes of the target moving image data. Whether or not the scene of the target moving image data is switched is determined by using the information from the scene change detection unit 24.

There is a high possibility that flicker will not be noticeable at the timing of scene switching. Therefore, the parameter setting unit 25 sets small values (initial values) as the time constants α and β when the scene is switched, and gradually increases the time constants α and β from the initial values to the target values. In the example of FIG. 10, the parameter setting unit 25 sets “0.10” as the time constant α and “0.00” which is smaller than “0.10” as the time constant β when the scene is switched. "Is set.

In the setting methods 2 and 3, the number of steps of changing from the initial value to the target value is not particularly limited. For example, after the state of the time constants α and β = initial values is maintained for a predetermined time, the time constants α and β may be instantaneously changed from the initial values to the target values (number of steps = 1). The time constants α and β may be gradually changed from the initial value to the target value in two or more steps.

As described above, according to the present embodiment, the parameters (time constants α, β) are set so that the difference between the second target brightness of each light source unit and the actual emission brightness of each light source unit is equal to or less than the threshold value. Is set. Then, the incident brightness is estimated based on the second target brightness of each light source unit, and the input image data is corrected based on the estimated incident brightness. As a result, deterioration of the image quality of the displayed image can be suppressed with high accuracy with a simple configuration.

In this embodiment, an example in which each light source unit has a plurality of types of color light source units has been described. However, each light source unit does not have to have a plurality of types of color light source units. For example, each light source unit may have only one or more white light sources (light sources that emit white light). In that case, the above processing for the color light source unit may be performed as a processing for the light source unit. Further, in that case, the processing of the RGB-BL luminance determination unit 12 and the processing of the time correction value selection unit 16 are omitted.

<Example 2>
Hereinafter, Example 2 of the present invention will be described. In the following, points different from Example 1 (configuration, processing, etc.) will be described in detail, and description of the same points as in Example 1 will be omitted. In this embodiment, the second target brightness is corrected in consideration of the change in the emission brightness (emission brightness of the light source unit) due to the time LPF processing with respect to the drive value, and the incident brightness is estimated based on the corrected second target brightness. NS. As a result, the incident luminance can be estimated with higher accuracy, and deterioration of the image quality of the displayed image can be suppressed with higher accuracy.

FIG. 11 is a block diagram showing a configuration example of the display device 101 according to this embodiment. In FIG. 11, the same functional units as those in the first embodiment (FIG. 1) are designated by the same reference numerals as those in the first embodiment. As shown in FIG. 11, the display device 101 includes each functional unit of the display device 1 of the first embodiment and a BL luminance correction unit 102.

The BL brightness correction unit 102 performs correction processing for correcting the second target brightness based on the time constant β (the degree of suppression of the time change of the drive value) so that the target brightness approaches the actual emission brightness of the light source unit. The third target brightness of each light source unit is acquired by performing the above. Specifically, the BL brightness correction unit 102 corrects the second target brightness by considering the change in the emission brightness (emission brightness of the light source unit) due to the time LPF processing with respect to the drive value based on the time constant β. As a result, a third target brightness close to the actual emission brightness can be obtained. Then, the BL brightness correction unit 102 notifies the incident brightness estimation unit 9 of the third target brightness of each light source unit. In this embodiment, the incident brightness estimation unit 9 estimates the incident brightness based on the third target brightness of each light source unit.

A specific example of the processing of the BL luminance correction unit 102 will be described. First, the BL luminance correction unit 102 uses the following equation 11 to obtain a difference value ΔBLC between the second target luminance BLC (x, y) of the current frame and the second target luminance PRBLC (x, y) of the previous frame. (X, y) is calculated.

ΔBLC (x, y) = BLC (x, y) -PRBLC (x, y)
... (Equation 11)

Next, the BL luminance correction unit 102 calculates the amount of change hΔBLC (x, y) from the time constant β and the difference value ΔBLC (x, y) using the following equation 12. When the emission brightness of the light source unit increases from the previous frame to the current frame, the amount of increase (increase rate) of the emission brightness between frames is reduced by the time LPF processing with respect to the drive value. On the other hand, when the emission brightness of the light source unit decreases from the previous frame to the current frame, the decrease amount (decrease rate) of the emission brightness between the frames is reduced by the time LPF processing with respect to the drive value. By using Equation 12, the amount of change in the emission brightness of the light source unit from the previous frame to the current frame hΔBLC (x, y) is estimated with high accuracy in consideration of the change in the emission brightness due to the time LPF processing with respect to the drive value. can do.

hΔ (x, y) = (1-β) × ΔBLC (x, y) ... (Equation 12)

Then, the BL luminance correction unit 102 adds the amount of change hΔBLC (x, y) to the second target luminance PRBLC (x, y) of the front frame, as shown in the following equation 13. Thereby, the third target brightness hBLC (x, y), which is very close to the actual emission brightness of the current frame, can be calculated. In other words, the actual emission brightness of the current frame can be estimated with high accuracy.

hBLC (x, y) = PRBLC (x, y) + hΔBLC (x, y)
... (Equation 13)

The method for determining the third target brightness hBLC (x, y) is not limited to the above method. For example, the third target luminance hBLC (x, y) may be determined by the following method. According to the following method, the third target luminance hBLC (x, y) can be obtained more easily than the above method.

First, the BL luminance correction unit 102 calculates the gain value hGain using the following equation 14. In the formula 14, “Gain” is a time correction value (gain value) selected by the time correction value selection unit 16. For example, when the gain value Gain = 0.8 and the time constant β = 0.75, the gain value hGain = 1-{(1-0.8) × (1-0.75)} = 1-0. 05 = 0.95 is obtained. By correcting the time correction value using the time constant β in this way, the time correction value is brought closer to 1. Here, the time correction value increases from 0.8 to 0.95. The "process of bringing the time correction value closer to 1" can also be said to be "a process of reducing the amount of decrease in emission brightness due to the process of the drive time correction unit 17."

hGain = 1-{(1-Gain) × (1-β)} ・ ・ ・ (Equation 14)

Next, the BL luminance correction unit 102 calculates the third target luminance hBLC (x, y) of the current frame from the gain value hGain and the second target luminance BLC (x, y). The BL luminance correction unit 102 switches the calculation formula (calculation formula for calculating the third target luminance hBLC (x, y)) according to the situation as follows. Thereby, the third target brightness hBLC (x, y) close to the actual emission brightness of the current frame can be calculated.

(Situation 1)
Situation 1 is a situation in which the emission brightness of the light source unit decreases from the previous frame to the current frame. Situation 1 can also be said to be "a situation in which the difference value ΔBLC (x, y) is negative". As described above, for the light source unit corresponding to the situation 1, the amount of decrease (decrease rate) of the emission brightness between frames is reduced by the time LPF processing with respect to the drive value. Therefore, for the light source unit corresponding to the situation 1, the gain value hGain may be multiplied by the second target luminance BLC (x, y) as shown in the following equation 15. Thereby, the third target brightness hBLC (x, y) close to the actual emission brightness can be calculated.

hBLC (x, y) = BLC (x, y) x hGain ... (Equation 15)

(Situation 2)
Situation 2 is a situation in which the emission brightness of the light source unit increases from the previous frame to the current frame. Situation 2 can be said to be "a situation in which the difference value ΔBLC (x, y) is positive". For the light source unit corresponding to the situation 2, when the equation 15 is used, the third target brightness hBLC (x, y) lower than the second target brightness BLC (x, y) is calculated. That is, the difference between the actual emission brightness and the target brightness increases. As described above, for the light source unit corresponding to the situation 2, the increase amount (increase rate) of the emission brightness between frames is reduced by the time LPF processing with respect to the drive value. Therefore, for the light source unit corresponding to the situation 2, as shown in the following equation 16, the second target luminance BLC (x, y) may be multiplied by the reciprocal of the gain value hGain. Thereby, the third target brightness hBLC (x, y) close to the actual emission brightness can be calculated.

hBLC (x, y) = BLC (x, y) x (1 / hGain)
... (Equation 16)

(Situation 3)
Situation 3 is a situation in which the emission brightness of the light source unit does not change from the previous frame to the current frame. Situation 3 can also be said to be "a situation in which the difference value ΔBLC (x, y) is 0". For the light source unit corresponding to the situation 3, the third target luminance hBLC (x, y) may be calculated using the equation 15, or the third target luminance hBLC (x, y) may be calculated using the equation 16. May be done.

As described above, according to the present embodiment, the second target brightness is corrected in consideration of the change in the emission brightness due to the time LPF processing with respect to the drive value, and the incident brightness is estimated based on the corrected second target brightness. Will be done. As a result, the incident luminance can be estimated with higher accuracy, and deterioration of the image quality of the displayed image can be suppressed with higher accuracy.

It should be noted that each functional part of the devices of Examples 1 and 2 may or may not be individual hardware. The functions of two or more functional units may be realized by common hardware. Each of the plurality of functions of one functional unit may be realized by individual hardware. Two or more functions of one functional unit may be realized by common hardware. Further, each functional part may or may not be realized by hardware. For example, the device may have a processor and a memory in which the control program is stored. Then, the function of at least a part of the functional parts of the device may be realized by the processor reading the control program from the memory and executing it.

It should be noted that Examples 1 and 2 are merely examples, and the present invention also includes configurations obtained by appropriately modifying or changing the configurations of Examples 1 and 2 within the scope of the gist of the present invention. A configuration obtained by appropriately combining the configurations of Examples 1 and 2 is also included in the present invention.

<Other Examples>
The present invention supplies a program that realizes one or more functions of the above-described embodiment to a system or device via a network or storage medium, and one or more processors in the computer of the system or device reads and executes the program. It can also be realized by the processing to be performed. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

1,101: Display device 2: Liquid crystal panel unit 3: Backlight unit 6: BL brightness determination unit 7: 1st time LPF processing unit 9: Incident brightness estimation unit 11: Image correction unit 13: Drive time determination unit 18: No. 2-hour LPF processing unit 25: Parameter setting unit

Claims (12)

A light emitting means having a plurality of light source units and
A display means for displaying an image by modulating the light emitted from the light emitting means based on the image data, and a display means.
For each light source unit, a first determination means for determining the first target brightness, which is the target brightness of the light source unit, based on the input image data, and
The first correction for acquiring the second target brightness of each light source unit by performing the first correction process for correcting the first target brightness for each light source unit so that the time change of the target brightness between frames is suppressed. Means and
For each light source unit, a second determination means for determining a first drive value, which is a drive value for controlling the emission brightness of the light source unit, based on the second target brightness.
A second correction means for acquiring the second drive value of each light source unit by performing a second correction process for correcting the first drive value for each light source unit so that the time change of the drive value is suppressed.
An estimation means that estimates the incident brightness, which is the brightness of the light emitted from the light emitting means when it is incident on the display means, based on the second target brightness of each light source unit.
A third correction means that corrects the input image data based on the incident brightness estimated by the estimation means, and
The first parameter used in the first correction process and the second correction process so that the difference between the second target brightness of each light source unit and the actual emission brightness of each light source unit is equal to or less than the first threshold value. A setting means for setting both the second parameter used in
A reception means that can accept requests from users,
Have,
The plurality of light source units are driven using the second drive value, and the plurality of light source units are driven.
The display means modulates the light emitted from the light emitting means based on the input image data corrected by the third correction means.
The setting means, when the request is made,
As the first parameter, a first value according to the request is set, and the first value is set.
A display device characterized in that a second value according to the request is set as the second parameter. The setting means has the first parameter and the second parameter so that the time change of the drive value to the first drive value is performed at a speed faster than the time change of the target brightness to the first target brightness. The display device according to claim 1, wherein parameters are set. The drive value is a value related to the drive time of the light source unit.
The display device is
When the total drive time, which is the sum of the plurality of drive times corresponding to the plurality of light source units, is longer than the second threshold value based on the first drive value of each light source unit, the total drive time is said to be the first. Further, it has a fourth correction means for acquiring the third drive value of each light source unit by correcting the first drive value of each light source unit so as to be 2 threshold values or less.
The display device according to claim 1 or 2, wherein the second correction process is a process for correcting the third drive value. The display device according to any one of claims 1 to 3, wherein the second determining means determines the first driving value of each light source unit in consideration of the luminous efficiency of each light source unit. It further has a detecting means for detecting the brightness of the light emitted from the light emitting means.
4. The second determination means is characterized in that the first drive value of each light source unit is determined based on the second target brightness of each light source unit and the detection result of the detection means. The display device described. The display device according to any one of claims 1 to 5, wherein the request is a request relating to the contrast of the image displayed by the display means. The requirement is a requirement regarding the current value supplied to the light emitting means.
When there is a request for a high current value, the setting means sets a second parameter in which the degree of suppression of the time change of the drive value is smaller than that of the second parameter when there is a request for a low current value. The display device according to any one of claims 1 to 5, which is characterized. In the display device, the image data of each frame of the moving image data is sequentially used as the input image data.
The display device further includes a scene change detecting means for detecting a scene change of the moving image data.
The setting means is used when the scene of the moving image data is changed.
A third value is set as the first parameter,
A fourth value is set as the second parameter,
The first parameter is gradually changed from the third value to a fifth value in which the degree of suppression of the time change of the target brightness is larger than the third value.
Claims 1 to 1, characterized in that the second parameter is gradually changed from the fourth value to a sixth value in which the degree of suppression of the time change of the driving value is larger than the fourth value. 7. The display device according to any one of 7. The display device has a plurality of display modes.
The setting means is used when the display mode of the display device is switched.
A seventh value is set as the first parameter,
An eighth value is set as the second parameter,
The first parameter is gradually changed from the seventh value to a ninth value in which the degree of suppression of the time change of the target brightness is larger than the seventh value.
Claims 1 to 1, characterized in that the second parameter is gradually changed from the eighth value to a tenth value in which the degree of suppression of the time change of the driving value is larger than the eighth value. 8. The display device according to any one of 8. By performing a third correction process for each light source unit to correct the second target brightness based on the degree of suppression of the time change of the drive value so that the target brightness approaches the actual emission brightness of the light source unit. Further, it has a fifth correction means for acquiring the third target brightness of the light source unit.
The display device according to any one of claims 1 to 9, wherein the estimation means estimates the incident brightness based on the third target brightness of each light source unit. A light emitting means having a plurality of light source units and
A control method for a display device including a display means for displaying an image by modulating the light emitted from the light emitting means based on image data.
For each light source unit, the first determination step of determining the first target brightness, which is the target brightness of the light source unit, based on the input image data, and
The first correction for acquiring the second target brightness of each light source unit by performing the first correction process for correcting the first target brightness for each light source unit so that the time change of the target brightness between frames is suppressed. Steps and
For each light source unit, a second determination step of determining a first drive value, which is a drive value for controlling the emission brightness of the light source unit, based on the second target brightness.
A second correction step of acquiring the second drive value of each light source unit by performing a second correction process of correcting the first drive value for each light source unit so that the time change of the drive value is suppressed.
An estimation step of estimating the incident brightness, which is the brightness of the light emitted from the light emitting means at the time of incidence on the display means, based on the second target brightness of each light source unit.
A third correction step that corrects the input image data based on the incident brightness estimated in the estimation step, and
The first parameter used in the first correction process and the second correction process so that the difference between the second target brightness of each light source unit and the actual emission brightness of each light source unit is equal to or less than the first threshold value. Setting steps to set both with the second parameter used in
The reception step to receive the request from the user and
Have,
The plurality of light source units are driven using the second drive value, and the plurality of light source units are driven.
The display means modulates the light emitted from the light emitting means based on the input image data corrected in the third correction step.
In the setting step, when the request is made,
As the first parameter, a first value according to the request is set, and the first value is set.
A control method characterized in that a second value according to the request is set as the second parameter. A program for causing a computer to execute each step of the control method according to claim 11.

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