JP2012145640A - Image display apparatus and control method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image display device able to reduce variation in LED luminance deterioration in a backlight and able to appropriately display a still area of an image.SOLUTION: The image display apparatus comprises: setting means configured to set a light emission luminance value of an LED light for each divided area; detecting means configured to detect a still divided area where the fluctuation range of the light emission luminance value has been equal to or below a threshold for a predetermined period or longer; altering means configured such that the light emission luminance value of the LED light in the still divided area is altered to a value different from the value set in the beginning by the setting means, by a value equal to or higher than the threshold, and the light emission luminance value of the LED light in an adjacent divided area, which is adjacent to the still divided area and has not been detected as a still divided area by the detecting means, is altered to the value at which it has been set as the LED light in the still divided area in the beginning by the setting means; and light emitting control means configured such that the LED light in the still divided area and adjacent divided area is emitted at the light emission luminance value altered by the altering means and LED light in divided areas other than those areas is emitted at the light emission luminance value set by the setting means.

Description

  The present invention relates to an image display device using an LED backlight and a control method thereof.

  Conventionally, in an image display apparatus having a backlight capable of local dimming control, a method for reducing variations in luminance deterioration of LED lights due to local dimming control has been proposed. For example, Patent Document 1 describes a technique for providing a display device with an illuminance sensor so that local dimming control is turned off when the illuminance is high so that variations in luminance deterioration of the LED light do not occur. . Japanese Patent Application Laid-Open No. 2004-228561 discloses that backlight emission control is performed so that the difference in accumulated light emission time between the upper backlight and the lower backlight does not exceed a threshold value.

JP 2009-204825 A JP 2008-261993 A

However, the image display device described in Patent Document 1 has the following problems. When this image display device is always used indoors, the luminance detected by the illuminance sensor may always be low, and in this case, the local dimming control can hardly be turned off.
That is, in the image display device described in Patent Document 1 described above, when used in a place with low illuminance, there is almost no opportunity to turn off local dimming control, and variation in luminance deterioration of the LED light may not be reduced.
Further, in the technique described in Patent Document 2, when the lighting state of the upper backlight and the lower backlight is switched while displaying an image including the still area, the display brightness of the still area changes, In some cases, the image looks uncomfortable.

  Accordingly, an object of the present invention is to provide a technology capable of reducing variations in luminance deterioration of LED lights and suitably displaying a still area of an image in an image display apparatus having a backlight capable of local dimming control. Is to provide.

The present invention includes a backlight having a plurality of LED lights,
A display panel having a plurality of pixels that change the transmittance of light from the backlight;
And the backlight is an image display device configured by arranging one or more LED lights corresponding to each of a plurality of divided areas dividing the display area of the display panel,
A setting means for setting a light emission luminance value of the LED light for each of the divided regions in accordance with an input video signal;
Based on the history of the light emission luminance value of the LED light for each of the divided regions set by the setting means, the divided region corresponding to the LED light in which the variation range of the light emission luminance value is not more than a predetermined threshold value continues for a predetermined period or longer. Detecting means for detecting a still divided region,
The setting means determines the emission luminance value of the LED light in the stationary divided area by the setting means.
The difference from the light emission luminance value set for the D light is changed to a light emission luminance value larger than the threshold value, and is a divided region adjacent to the still divided region and is not detected as a still divided region by the detection means. Changing means for changing the light emission luminance value of the LED light of the divided area to the light emission luminance value set by the setting means for the LED light of the stationary divided area;
When a stationary divided area is detected by the detecting means, the LED light of the stationary divided area and the adjacent divided area is caused to emit light with the light emission luminance value changed by the changing means, and the LEDs of the other divided areas are Light emission control means for emitting light at a light emission luminance value set by the setting means;
It is an image display apparatus which has.

The present invention includes a backlight having a plurality of LED lights,
A display panel having a plurality of pixels that change the transmittance of light from the backlight;
And the backlight is a method of controlling an image display device in which one or more LED lights are arranged corresponding to each of a plurality of divided areas dividing the display area of the display panel. ,
A setting step for setting a light emission luminance value of the LED light for each of the divided regions according to an input video signal;
Based on the history of the light emission luminance value of the LED light for each of the divided regions set in the setting step, the divided region corresponding to the LED light in which the variation range of the light emission luminance value is equal to or less than a predetermined threshold continues for a predetermined period or more. A detection step of detecting a stationary divided region,
The light emission luminance value of the LED light in the stationary divided region is changed to a light emission luminance value in which the difference from the light emission luminance value set in the LED light of the stationary divided region in the setting step is larger than the threshold, and the stationary division is performed. The light emission luminance value of the LED light of the divided region adjacent to the region and not detected as the stationary divided region by the detection step is set to the light emission luminance value set for the LED light of the stationary divided region in the setting step. Change process to change,
When a stationary divided region is detected by the detection step, the LED light of the stationary divided region and the adjacent divided region is caused to emit light with the light emission luminance value changed by the changing step, and the LEDs of the other divided regions A light emission control step of causing the light to emit light at the light emission luminance value set by the setting step;
Is a control method of an image display apparatus having

  ADVANTAGE OF THE INVENTION According to this invention, in the image display apparatus which has a backlight which can perform local dimming control, while the dispersion | variation in the brightness degradation of LED light can be reduced, the still area of an image can be displayed suitably.

1 is a block diagram illustrating a configuration of an image display device according to a first embodiment. The figure which shows the time change of the luminance control value of an input video signal and BL control area Flowchart of processing for changing the brightness control value of the BL control area Diagram of luminance change when the luminance control value of the BL control area is changed one area at a time Diagram of change in brightness when the brightness control value of the BL control area is changed simultaneously in multiple areas FIG. 6 is a block diagram illustrating a configuration of an image display device according to the second embodiment. Flowchart of processing for changing the brightness control value of the BL control area Schematic diagram for calculating the light diffusion state of the lit BL control area Schematic diagram showing the BL control area lighting state and changes in the brightness value of the BL control area Schematic diagram showing the BL control area lighting state and changes in the brightness value of the BL control area Schematic diagram showing the BL control area lighting state and changes in the brightness value of the BL control area

Example 1
A first embodiment will be described. FIG. 1 is a block diagram showing the configuration of an image display apparatus to which the present invention is applied. In the following description, “backlight” may be referred to as “BL” (abbreviation of Back Light).
The image display device 1 in FIG. 1 includes a local dimming control unit 101, a stationary BL control area detection unit 102, a BL area movement control calculation unit 103, an LED control unit 104, an LED unit 105, and a display unit 106.
The LED unit 105 constitutes a backlight having a plurality of LED lights. The display unit 106 constitutes a liquid crystal panel (display panel) in which pixels (liquid crystal elements) that express gradation by changing the transmittance of light from the backlight are arranged in a matrix.

  The light emission luminance of the LED light is controlled in units of “BL control area” that is a set of one or a plurality of LED lights. In this embodiment, as shown in FIG. 2B, the display area of the display unit 106 is divided into a matrix, and a “BL control area” is defined as a set of LED lights that irradiate the pixels in each divided area. That is, the LED unit 105 (backlight) is configured by arranging one or more LED lights corresponding to each of a plurality of divided areas that divide the display area of the display panel.

  In the example shown in FIG. 2B, since the display area of the display unit 106 is divided into 54 divided regions of 9 × 6 in the horizontal direction, the plurality of LED lights constituting the LED unit 105 are 54 BL. Grouped into control areas. LED lights belonging to one BL control area are controlled to emit light with the same luminance.

  In FIG. 1, the local dimming control unit 101 calculates BL control area lighting information from the input video signal. The BL control area lighting information is information indicating a luminance control value (light emission luminance value) for controlling the light emission luminance of the LED light for each BL control area (each divided region).

  FIG. 2 shows an example of the time change of the video signal input to the local dimming control unit 101 and the lighting state of the BL control area. FIG. 2A is a diagram showing frame images based on an input video signal at three different times. As shown in the frame image 1011, the frame image 1012, and the frame image 1013 in FIG. 2A, here, a bright windmill appears in the center of the screen with a dark background, and the wing portion of the windmill changes with time. A video to be described will be described as an example.

  When this video signal is input, the local dimming control unit 101 turns on the BL control area so that only the BL control area corresponding to the position where the image of the bright windmill exists in the frame images 1011, 1012, and 1013 is turned on. Calculate information. Further, the local dimming control unit 101 calculates BL control area lighting information so that the BL control area corresponding to the dark background is turned off.

FIG. 2B is a diagram illustrating a lighting state of the BL control area when each BL control area is caused to emit light based on the BL control area lighting information thus calculated. The BL control area lighting states 1014, 1015, and 1016 in FIG. 2B indicate the lighting state of the BL control area when displaying the frame images 1011, 1012, and 1013, respectively.
In the BL control area lighting states 1014, 1015, and 1016 in FIG. 2B, one square frame painted with diagonal lines indicates a BL control area that does not light, and one square frame painted with white lights up. Indicates the control area.

As shown in the BL control area lighting states 1014, 1015, and 1016 in FIG. 2B, the local dimming control unit 101 includes four BLs corresponding to positions where the windmill image is located.
BL control area lighting information is calculated so that only the control areas A, B, C, and D are lit.
The local dimming control unit 101 outputs BL control area lighting information calculated from the input video signal to the stationary BL control area detection unit 102. The local dimming control unit 101 functions as a setting unit of the present invention.

  When a video signal having almost no change in the position and size of the bright and dark portions in the frame image as shown in FIG. 2 (a) is input, the BL control area lighting state is as shown in FIG. 2 (b). It does not change. For this reason, during the period in which such video signal input continues, control is performed so that the specific BL control area continues to be lit at a luminance value that hardly changes.

  In the example shown in FIG. 2, the brightness control values of the BL control areas A, B, C, and D that are turned on hardly change over time during the period in which the video signal of the windmill as shown in FIG. . Since the LED light belonging to the BL control area in which the time change of the brightness control value is small continues to emit light with the same or almost unchanged light emission brightness for a long time, the brightness deterioration is faster or slower than the average brightness deterioration. This tends to cause variations in luminance degradation.

  The stationary BL control area detection unit 102 detects a BL control area (hereinafter referred to as a stationary BL control area) in which the luminance control value hardly changes based on the history of the BL control area lighting information calculated by the local dimming control unit 101. To do. The stationary BL control area detection unit 102 compares the amount of change in luminance control value (variation width) with a predetermined threshold value Ta (hereinafter referred to as a variation luminance difference determination value) for each BL control area, thereby Perform area detection.

  The stationary BL control area detection unit 102 determines that the BL control area in which the variation range of the luminance control value is not more than the variation luminance difference determination value Ta (below the threshold value) continues for a predetermined period or more is a stationary BL control area, The stillness determination value Sh of the BL control area is set to 1. On the other hand, the stationary determination value Sh is set to 0 for the BL control area where the state where the variation range of the luminance control value is not more than the variation luminance difference determination value Ta continues for a predetermined period or longer.

  In this way, by determining whether or not the state in which the variation range of the luminance control value is equal to or less than the variation luminance difference determination value Ta has continued for a predetermined period or longer, the change in the emission luminance of the LED light is small, and the luminance degradation of the LED light It is possible to extract a BL control area where variations are likely to occur.

  The predetermined period is a reference value for the duration of the same luminance control value that can be determined to easily cause variations in luminance deterioration, and is a value such as a frame order, a second order, a minute order, etc., depending on the configuration of the image display device 1. become. The stationary BL control area corresponds to the stationary divided area of the present invention. The stationary BL control area detection unit 102 functions as detection means of the present invention.

  The stationary BL control area detection unit 102 outputs the stationary determination value Sh for each BL control area and the BL control area lighting information input from the local dimming control unit 101 to the BL area movement control calculation unit 103.

Note that the method by which the stationary BL control area detection unit 102 detects the stationary BL control area is not limited to the above method.
For example, the BL control area lighting information is sampled and stored at predetermined time intervals. Each time the BL control area lighting information is saved, the variation range of the luminance control value is obtained for each BL control area by comparing the stored BL control area lighting information with the previously saved BL control area lighting information. To do. And based on the fluctuation range of the brightness | luminance control value for every acquired BL control area, a stationary BL control area can be detected. Also, the variation range of the brightness control value may be acquired for each BL control area by reading out the BL control area lighting information whose stored time is separated by a certain time and comparing the read BL control area lighting information. . Other,
A stationary BL control area can be detected by various methods based on a change in luminance control value for each BL control area.

  The BL area movement control calculation unit 103 generates a BL control area based on the static determination value Sh for each BL control area input from the static BL control area detection unit 102 and the BL control area lighting information calculated by the local dimming control unit 101. Lighting change information is calculated. The BL control area lighting change information is information indicating a change in the luminance control value of the stationary BL control area among the luminance control values for each BL control area indicated in the BL control area lighting information calculated by the local dimming control unit 101. is there.

  The BL area movement control calculation unit 103 calculates BL control area lighting change information so as to reduce variation in luminance deterioration of LED lights in the BL control area due to the presence of the stationary BL control area. Hereinafter, a method for calculating the BL control area lighting change information will be described. In the present embodiment, control for changing the light emission luminance of the stationary BL control area based on the BL control area lighting change information calculated by the BL area movement control calculation unit 103 is referred to as stationary BL control area movement control. The BL area movement control calculation unit 103 functions as a changing unit of the present invention.

<Still BL control area movement control (part 1)>
First, stationary BL control area movement control in which the luminance control value of the stationary BL control area is sequentially changed one by one when there are a plurality of stationary BL control areas will be described with reference to FIGS.
FIG. 3 is a flowchart showing a calculation procedure for changing the luminance control value of the stationary BL control area.
FIG. 4 is a schematic diagram showing a change in the BL control area lighting state when the brightness control value of the stationary BL control area is changed.

In step S1021 of FIG. 3, the BL area movement control calculation unit 103 sets the luminance control value of the stationary BL control area (the BL control area in which the stationary determination value Sh is set to 1 in the stationary BL control area detection unit 102). It is determined whether or not it is equal to or greater than a predetermined threshold value Jh (hereinafter referred to as a brightness determination value).
The LED light is more likely to deteriorate in luminance as it emits light with higher luminance. This step S1021 is a step for extracting a stationary BL control area in which it can be determined that luminance deterioration of the LED light is likely to occur because light is emitted with high luminance from the stationary BL control area.
The processing of the BL area movement control calculation unit 103 extracts a stationary BL control area (hereinafter referred to as a high luminance stationary BL control area) whose luminance control value is equal to or higher than the brightness determination value Jh (brightness determination value or higher), The process proceeds to step S1022.

In step S1022, the BL area movement control calculation unit 103 sets a predetermined difference in luminance control value from the adjacent BL control area (hereinafter referred to as the adjacent BL control area) for each high-luminance stationary BL control area extracted in step S1021. It is determined whether or not the threshold value Kh is greater than or equal to. Hereinafter, the predetermined threshold value Kh is referred to as an adjacent luminance difference determination value.
The greater the difference between the brightness control value of the high brightness stationary BL control area and the brightness control value of the adjacent BL control area, the more likely the variation in the LED light brightness deterioration will occur in these two BL control areas. . This step S1022 is a step for extracting a high luminance stationary BL control area having a large difference in luminance control value from the adjacent BL control area among the high luminance stationary BL control areas.

The BL area movement control calculation unit 103 sets a high-brightness still BL control area in which the difference in brightness control value from the adjacent BL control area is equal to or greater than the adjacent brightness difference determination value Kh (adjacent brightness difference determination value or more)
In the L control area movement control, the brightness control value is determined to be changed. The high-luminance stationary BL control area that is the target for changing the luminance control value in the stationary BL control area movement control is hereinafter referred to as a change-target BL control area.
After extracting the change target BL control area, the BL area movement control calculation unit 103 proceeds to the process of step S1023.

  In addition, when there are a plurality of BL control areas adjacent to the high-intensity static BL control area, if the above condition is satisfied with any one of the adjacent BL control areas, the high-intensity static BL control area is to be changed. A BL control area may be used. Alternatively, when the above condition is satisfied with all adjacent BL control areas, the high-intensity stationary BL control area may be set as the change target BL control area.

An example of the change target BL control area is shown in a BL control area lighting state 1041 in FIG. In the BL control area lighting state 1041 in FIG. 4, the four BL control areas A, B, C, and D painted in white are the change target BL control areas.
That is, in these four BL control areas, the state in which the change amount of the brightness control value is not more than the variation brightness difference determination value Ta continues for a predetermined period, and the brightness control value is not less than the brightness determination value Jh. In addition, the difference in brightness control value from the adjacent BL control area is equal to or greater than the adjacent brightness difference determination value Kh.
Hereinafter, the luminance control values of the four change target BL control areas A, B, C, and D are determined from the luminance control values calculated by the local dimming control unit 101 (luminance control values determined in the BL control area lighting information). change.

In step S1023, the BL area movement control calculation unit 103 sets the brightness control value of the change target BL control area extracted in step S1022 in the adjacent BL control area. Thereby, the luminance control value set in the change target BL control area moves to the adjacent BL control area.
That is, the BL control area lighting state is changed so that the BL control area adjacent to the change target BL control area is turned on with the luminance control value set in the change target BL control area. Further, the luminance control value set in the adjacent BL control area is set in the change target BL control area. Alternatively, in the change target BL control area, an arbitrary luminance control value whose difference from the initially set luminance control value exceeds the variation luminance difference determination value Ta may be set. Alternatively, the change target BL control area may be simply turned off.

When a plurality of change target BL control areas are extracted in step S1022, the BL area movement control calculation unit 103 moves the brightness control value in the change target BL control area as described above as one change target BL control. Do it in order by area.
The BL area movement control calculation unit 103 calculates BL control area lighting change information for realizing the movement of the luminance control value in the change target BL control area, and outputs the BL control area lighting change information to the LED control unit 104.

  In the BL control area lighting states 1042, 1043, 1044, and 1045 in FIG. 4, the brightness control value of the target BL control area to be changed is moved to the adjacent BL control area one by one in order from the BL control area lighting state 1041. The change of the BL control area lighting state in the case of failure is shown.

First, among the four change target BL control areas painted in white in the BL control area lighting state 1041, the lower right change target BL control area A is set to the non-lighting state and the change target BL control area A is set to the non-lighting state. Next, the adjacent BL control area A ′ is turned on. As a result, the BL control area lighting state 1041 changes to the BL control area lighting state 1042.
In the adjacent BL control area A ′, the brightness control value set in the change target BL control area A in the BL control area lighting information calculated by the local dimming control unit 101 is set.

Next, the change of the brightness control value of the change target BL control area A and the adjacent BL control area A ′ is restored. Further, among the four change target BL control areas painted in white in the BL control area lighting state 1041, the lower left change target BL control area B is set to the non-lighting state, and the change target BL control area B is set to the non-lighting state. The next adjacent BL control area B ′ is turned on.

As a result, the BL control area lighting state 1042 changes to the BL control area lighting state 1043. In the adjacent BL control area B ′, the brightness control value set in the change target BL control area B in the BL control area lighting information calculated by the local dimming control unit 101 is set.

Next, the change of the luminance control value of the change target BL control area B and the adjacent BL control area B ′ is restored. Furthermore, among the four change target BL control areas painted in white in the BL control area lighting state 1041, the upper left change target BL control area C is set to the non-lighting state, and the change target BL control area C is set to the non-lighting state. The adjacent BL control area C ′ that is one level above is turned on.

As a result, the BL control area lighting state 1043 changes to the BL control area lighting state 1044. In the adjacent BL control area C ′, the brightness control value set in the change target BL control area C in the BL control area lighting information calculated by the local dimming control unit 101 is set.

Next, the change of the luminance control value of the change target BL control area C and the adjacent BL control area C ′ is restored. Further, of the four change target BL control areas painted in white in the BL control area lighting state 1041, the upper right change target BL control area D is set to the non-lighting state, and the change target BL control area D is set to the non-lighting state. The adjacent BL control area D ′ that is one level above is turned on.

As a result, the BL control area lighting state 1044 changes to the BL control area lighting state 1045. In the adjacent BL control area D ′, the luminance control value set in the change target BL control area D in the BL control area lighting information calculated by the local dimming control unit 101 is set.

Next, the change of the luminance control value of the change target BL control area D and the adjacent BL control area D ′ is restored to the original, and the BL control area lighting state 1042 is set again. As a result, the BL control area lighting state 1045 changes to the BL control area lighting state 1042.

Similarly, the BL control area lighting state is changed in the order of BL control area lighting state 1042 → 1043 → 1044 → 1045 → 1042 shown in FIG. Thereby, the control for moving the luminance control value of the change target BL control area to the adjacent BL control area is sequentially performed for each change target BL control area.
The BL area movement control calculation unit 103 calculates BL control area lighting change information for realizing stationary BL control area movement control in which the BL control area lighting state changes in this way, and outputs the information to the LED control unit 104. .
Transition between BL control area lighting states 1042, 1043, 1044, and 1045
For example, it is performed every frame, every several frames, every fixed period, or the like.

  While the change target BL control area satisfies the conditions of the change target BL control area, the above-described stationary BL control area movement control is continuously performed. The condition of the change target BL control area is that the stillness determination value Sh is 1, the brightness control value is the brightness determination value Jh or more, and the difference in the brightness control value from the adjacent BL control area is the adjacent brightness difference determination value Kh or more. This is the condition.

  In addition, when there are a plurality of BL control areas adjacent to the change target BL control area, the adjacent BL control area to which the brightness control value of the change target BL control area is to be moved is any of the plurality of adjacent BL control areas. You may fix it. Alternatively, the adjacent BL control area to which the brightness control value of the change target BL control area is moved may be sequentially changed in the plurality of adjacent BL control areas. Alternatively, the adjacent BL control area to which the luminance control value of the change target BL control area is moved may be limited to an adjacent BL control area that satisfies the condition that the difference in luminance control value is equal to or greater than the adjacent luminance difference determination value Kh.

  In this way, the luminance control value of the BL control area determined to have a significant variation in the luminance degradation of the LED light is moved to the adjacent BL control area to emit light, thereby reducing the luminance degradation of the LED light in the plurality of BL control areas. Can be averaged. As a result, it is possible to reduce variations in luminance degradation of the LED light.

<Still BL control area movement control (part 2)>
Next, the stationary BL control area movement control for changing the luminance control value of the stationary BL control area at the same time when there are a plurality of stationary BL control areas will be described with reference to FIGS.
FIG. 5 is a schematic diagram showing a change in the BL control area lighting state when the brightness control value of the stationary BL control area is changed.

The processing content of step S1021 and step S1022 is the same as the case of the above-mentioned stationary BL control area movement control.
When a plurality of change target BL control areas are extracted in step S1022, the BL area movement control calculation unit 103 moves the luminance control value of the change target BL control area described above with respect to step S1023 to a plurality of change target BL control areas. About at the same time.

As a result, the brightness control values set in the plurality of change target BL control areas are simultaneously moved to the BL control areas adjacent to the respective change target BL control areas. That is, the BL control area lighting state is changed so that the BL control area adjacent to each change target BL control area is turned on with the brightness control value set in each of the plurality of change target BL control areas.
The BL area movement control calculation unit 103 calculates BL control area lighting change information for realizing the movement of the luminance control value in the change target BL control area, and outputs the BL control area lighting change information to the LED control unit 104.

  In the BL control area lighting states 1052, 1053, 1054, and 1055 in FIG. 5, the brightness control value of the change target BL control area is moved to the adjacent BL control area by two areas one after another from the BL control area lighting state 1051 as a starting point. The change of the lighting state of the BL control area in the case is shown.

First, among the four change target BL control areas painted in white in the BL control area lighting state 1051, the upper right change target BL control area D and the lower right change target BL control area A are set to the non-lighting state. In addition, the adjacent BL control area D ′ immediately above the change target BL control area D in the upper right non-lighting state is turned on, and the change target BL control area A in the lower right non-lighting state is one below. The adjacent BL control area A ′ is turned on.

As a result, the BL control area lighting state 1051 changes to the BL control area lighting state 1052. In the adjacent BL control areas A ′ and D ′, the brightness control values set in the change target BL control areas A and D in the BL control area lighting information calculated by the local dimming control unit 101 are set, respectively.

Next, the above-described change target BL control areas A and D and their adjacent BL control areas A ′ and D ′.
Undo the change of the brightness control value. Further, among the four change target BL control areas painted in white in the BL control area lighting state 1051, the upper left change target BL control area C and the lower left change target BL control area B are set to the non-lighting state.
In addition, the adjacent BL control area C ′ immediately above the change target BL control area C in the upper left non-lighting state is turned on, and the adjacent lower one of the change target BL control area B in the lower left non-lighting state is set. The BL control area B ′ is turned on.

As a result, the BL control area lighting state 1052 changes to the BL control area lighting state 1053. In the adjacent BL control areas B ′ and C ′, the luminance control values set in the change target BL control areas B and C in the BL control area lighting information calculated by the local dimming control unit 101 are set, respectively.

Next, the above-described change target BL control areas B and C and their adjacent BL control areas B ′ and C ′.
Undo the change of the brightness control value. Further, among the four change target BL control areas painted in white in the BL control area lighting state 1051, the upper left change target BL control area C and the upper right change target BL control area D are set to the non-lighting state.
Further, the adjacent BL control area C ″ on the left of the change target BL control area C in the upper left non-lighting state is turned on, and the change target BL control area D in the upper right non-lighting state is on the right of the change target BL control area D. The adjacent BL control area D ″ is turned on.

As a result, the BL control area lighting state 1053 changes to the BL control area lighting state 1054. In the adjacent BL control areas C ″ and D ″, the brightness control values set in the change target BL control areas C and D in the BL control area lighting information calculated by the local dimming control unit 101 are set, respectively. .

Next, the above-described change target BL control areas C and D and their adjacent BL control areas C ″ and D
Undo change of brightness control value of ''. Further, among the four change target BL control areas painted in white in the BL control area lighting state 1051, the lower left change target BL control area B and the lower right change target BL control area A are set to the non-lighting state.
In addition, the left adjacent BL control area B ″ left of the change target BL control area B in the lower left non-lighting state is turned on, and one right of the change target BL control area A in the lower right non-lighting state. The adjacent BL control area A ″ is turned on.

As a result, the BL control area lighting state 1054 changes to the BL control area lighting state 1055. In the adjacent BL control areas B ″ and A ″, the luminance control values set in the change target BL control areas B and A in the BL control area lighting information calculated by the local dimming control unit 101 are set, respectively. .

Next, the above-described change target BL control areas B, A and the adjacent BL control areas B ″, A
The change of the brightness control value of '' is restored and the BL control area lighting state 105 described above is again displayed.
Set to 2. As a result, the BL control area lighting state 1055 becomes the BL control area lighting state 10.
To 52.

Similarly, the BL control area lighting state is changed in the order of the BL control area lighting state 1052 → 1053 → 1054 → 1055 → 1052 shown in FIG. Thereby, the control for moving the luminance control value of the change target BL control area to the adjacent BL control area is simultaneously performed for a plurality of change target BL control areas.
The BL area movement control calculation unit 103 calculates BL control area lighting change information for realizing stationary BL control area movement control in which the BL control area lighting state changes in this way, and outputs the information to the LED control unit 104. .
Transitions between the BL control area lighting states 1052, 1053, 1054, and 1055 are performed, for example, every frame, every several frames, or at regular intervals.

  While the change target BL control area satisfies the conditions of the change target BL control area, the above-described stationary BL control area movement control is continuously performed. The condition of the change target BL control area is that the stillness determination value Sh is 1, the brightness control value is the brightness determination value Jh or more, and the difference in the brightness control value from the adjacent BL control area is the adjacent brightness difference determination value Kh or more. This is the condition.

  In addition, when there are a plurality of BL control areas adjacent to the change target BL control area, the adjacent BL control area to which the brightness control value of the change target BL control area is to be moved is any of the plurality of adjacent BL control areas. You may fix it. Alternatively, the adjacent BL control area to which the brightness control value of the change target BL control area is moved may be sequentially changed in the plurality of adjacent BL control areas. Alternatively, the adjacent BL control area to which the luminance control value of the change target BL control area is moved may be limited to an adjacent BL control area that satisfies the condition that the difference in luminance control value is equal to or greater than the adjacent luminance difference determination value Kh.

  When there are a plurality of change target BL control areas in this way, a group (corresponding to a still divided region group) of a plurality of change target BL control areas (two of the four in the above example) is selected. Stipulate. Then, the group of the change target BL control area whose luminance control value is to be changed is sequentially changed one by one from among a plurality of groups that can be defined based on the plurality of change target BL control areas.

  In the stationary BL control area movement control, the luminance control values of the plurality of change target BL control areas are simultaneously moved to the adjacent BL control area to emit light, thereby averaging the luminance deterioration of the LED light in the plurality of BL control areas. Is possible. As a result, it is possible to reduce variations in luminance degradation of the LED light.

  Based on the BL control area lighting change information input from the BL area movement control calculation unit 103, the LED control unit 104 causes a current to flow through the LED unit 105 to cause the LED light to emit light. The LED control unit 104 functions as a light emission control unit of the present invention.

  The LED unit 105 emits light at a current value determined for each BL control area output from the LED control unit 104.

  The display unit 106 displays the input video signal. The display unit 106 adjusts the drive voltage applied to the liquid crystal elements corresponding to each BL control area based on the video signal and the BL control area lighting change information input from the BL area movement control calculation unit 103.

As described above, the image display device 1 according to the first embodiment detects a stationary BL control area in which a luminance control value is small and a luminance deterioration variation is likely to occur based on a change in the luminance control value for each BL control area. . Then, by setting the detected brightness control value of the stationary BL control area as the brightness control value of the adjacent BL control area, the brightness control value of the stationary BL control area is moved to the adjacent BL control area.

As a result, since the luminance degradation between the stationary BL control area and the adjacent BL control area is averaged, it is possible to reduce the occurrence of variations in the luminance degradation of the LED lights.
Further, although the change target BL control area emits light with a brightness control value different from the originally set brightness control value, the BL control area adjacent to the change target BL control area is initially set in the change target BL control area. Light is emitted with the set brightness control value. Therefore, a change in display luminance of an image (still area) displayed in the display area corresponding to the change target BL control area is suppressed, and it is possible to suppress a sense of incongruity in the appearance of the image. According to the still BL control area movement control of the present embodiment, even when an image including a still area adjacent to the low brightness area with high brightness and small brightness variation is displayed on a full screen, for example, the image looks strange. It is possible to suppress variations in luminance deterioration of the backlight while suppressing the occurrence. Therefore, in an image display device having a backlight capable of local dimming control, luminance unevenness and color unevenness can be suppressed, and a still area of an image can be suitably displayed.

  Note that the method of moving the luminance control value of the stationary BL control area to the adjacent BL control area is not limited to the method described above. If the control is to turn off the stationary BL control area where the time change of the brightness control value is small and turn on the BL control area adjacent to it, the brightness deterioration is averaged between the stationary BL control area and the adjacent BL control area. Therefore, the problem of the present invention is solved.

  If the light emission state initially set in the BL control area adjacent to the stationary BL control area is not in the non-lighting state, the stationary BL control area is stopped in the lighting state of the adjacent BL control area instead of being in the non-lighting state. The BL control area may be turned on.

(Example 2)
In the second embodiment, the difference in luminance value of the target BL control area to be changed before and after changing the BL control area lighting state is set to be equal to or less than a predetermined threshold Nh (hereinafter referred to as “brightness fluctuation allowable value”). The possible stationary BL control area movement control will be described. The luminance variation allowable value Nh is a reference value for the amount of change in luminance value that is allowable for the user, and may be a fixed value that is determined in advance through experiments or the like, or may be a variable value that can be adjusted by the user. . In the second embodiment, a method of performing stationary BL control area movement control in consideration of the influence of light emission from a certain BL control area on the luminance value of the surrounding BL control area (the influence of diffused light) will be described.

FIG. 6 is a block diagram showing the configuration of the image display apparatus of this embodiment.
The difference between the image display device 2 of FIG. 6 and the image display device 1 of the first embodiment is that a BL diffusion light emission area calculation unit 107 is added, and a BL area diffusion movement control calculation unit 108 includes an LED control unit 104 and a display. The BL control area lighting change information is output to the unit 106.

  The image display device 2 configured as described above will be described below with a focus on differences from the image display device 1 of the first embodiment. In the present embodiment, it is assumed that the video signal shown in FIG. 2 is input to the local dimming control unit 101 as in the first embodiment. The local dimming control unit 101 and the stationary BL control area detection unit 102 are the same operations as those in the first embodiment, and thus the description thereof is omitted.

  Based on the BL control area lighting information calculated by the local dimming control unit 101, the BL diffused light area calculation unit 107 calculates diffused light luminance value information of the BL control area to be lit. The diffused light luminance value information is information on the luminance value for each BL control area calculated in consideration of the influence of diffused light from the lit BL control area on the surrounding BL control area. The BL diffusion light emission area calculation unit 107 functions as a calculation unit of the present invention.

A method of calculating the luminance value for each BL control area in consideration of the influence of diffused light from the lit BL control area will be described with reference to the flowchart of FIG. 7 and the schematic diagram of FIG.
FIG. 7 is a flowchart showing a procedure for calculating a luminance value for each BL control area in consideration of the influence of diffused light from the lit BL control area.
FIG. 8 is a schematic diagram showing a method of calculating the luminance value for each BL control area in consideration of the influence of diffused light from the lit BL control area.

  First, in step S2001, the BL diffusion light emission area calculation unit 107 selects a lit BL control area (hereinafter referred to as a lit BL control area) based on the BL control area lighting information input from the local dimming control unit 101. The process moves to step S2002. Here, it is assumed that the BL control areas A, B, C, and D shown in the BL control area lighting state 1041 in FIG. 4 are the lighting BL control areas extracted by the BL diffusion light emitting area calculation unit 107.

Next, in step S2002, the BL diffused light area calculation unit 107 calculates the brightness value of diffused light that affects the adjacent BL control area for each lighting BL control area extracted in step S2001.
A method for calculating the luminance value of the diffused light for each lighting BL control area will be described with reference to FIG.

FIG. 8B is a schematic diagram showing a BL control area lighting state in which only the upper left BL control area C is lit among the extracted four lighting BL control areas.
FIG. 8A shows the brightness value of the BL control area on the broken line 2011 in FIG. 8B calculated by the BL diffused light emission area calculation unit 107 in consideration of the influence of the diffused light from the lighting BL control area C. FIG.
As shown in FIG. 8A, the luminance value of the BL control area taking into account the diffused light from the lighting BL control area C is the largest in the lighting BL control area C and decreases as the distance from the lighting BL control area C increases. As shown in FIG. 8B, the BL control area around the lighting BL control area C is in a non-lighting state, but the luminance value is not zero due to the influence of diffused light from the lighting BL control area C.

  In this way, the BL diffused light area calculation unit 107 assumes a BL control area lighting state in which only one BL control area is lit (hereinafter referred to as a single lighting state), and from the lighting BL control area. The brightness value of each BL control area is calculated in consideration of the influence of diffused light. The brightness value of the BL control area thus calculated is hereinafter referred to as a diffused light brightness value. 8A shows only the brightness value of the BL control area on the broken line 2011 in FIG. 8B, the BL diffused light area calculation unit 107 calculates the brightness values of all the BL control areas.

  When there are a plurality of lighting BL control areas, the BL diffused light area calculation unit 107 calculates a diffused light luminance value assuming a single lighting state for each lighting BL control area. Here, the BL diffusion light emitting area calculation unit 107 similarly assumes the single lighting state of each lighting BL control area for the remaining three lighting BL control areas A, B, and D other than the above-described lighting BL control area C. Then, the diffused light luminance value is calculated.

  FIG. 8D is a schematic diagram showing a single lighting state in which only the upper right BL control area D is lit among the four lighting BL control areas. FIG. 8C shows the diffusion of the BL control area on the broken line 2012 calculated in consideration of the influence of the diffused light from the lighting BL control area D assuming the single lighting state shown in FIG. It is the figure which showed the light luminance value.

FIG. 8F is a schematic diagram showing a single lighting state in which only the lower left BL control area B is lit among the four lighting BL control areas. FIG. 8 (e) shows the diffusion of the BL control area on the broken line 2013 calculated in consideration of the influence of the diffused light from the lighting BL control area B, assuming the single lighting state shown in FIG. 8 (f). It is the figure which showed the light luminance value.

  FIG. 8H is a schematic diagram showing a single lighting state in which only the lower right BL control area A among the four lighting BL control areas is lit. FIG. 8G shows the diffusion of the BL control area on the broken line 2014 calculated in consideration of the influence of the diffused light from the lighting BL control area A assuming the single lighting state shown in FIG. It is the figure which showed the light luminance value.

  When the diffused light luminance value assuming a single lighting state is calculated for all the lighting BL control areas, the BL diffused light area calculation unit 107 proceeds to step S2003.

  Next, in step S2003, the BL diffused light area calculation unit 107 adds the diffused light luminance values of all the lighting BL control areas calculated in step S2002 for each BL control area. Thereby, the brightness value of each BL control area in the BL control area lighting state in which the four lighting BL control areas are simultaneously lighted is calculated.

FIG. 8J is a schematic diagram showing a BL control area lighting state in which all four lighting BL control areas are lit. FIG. 8 (i) is a diagram showing the diffused light luminance value of the BL control area on the broken line 2015 in the BL control area lighting state shown in FIG. 8 (j).
As shown in FIG. 8 (i), the diffused light calculated assuming the single lighting states of the four BL control areas shown in FIGS. 8 (a), (c), (e), and (g). The sum of the brightness values is the brightness value of each BL control area when all four BL control areas are lit.

  Next, in step S2004, the BL diffusion light emission area calculation unit 107 outputs the information on the luminance value of each BL control area calculated in step S2003 to the BL area diffusion movement control calculation unit 108.

The BL area diffusion movement control calculation unit 108 receives the brightness value information of each BL control area input from the BL diffusion light emission area calculation unit 107 and the stillness determination of each BL control area input from the stationary BL control area detection unit 102. BL control area lighting change information is calculated based on the value Sh.
The BL area diffusion movement control calculation unit 108 is configured so that the difference in luminance value of the change target BL control area before and after changing the BL control area lighting information by the stationary BL control area movement control is equal to or less than the luminance variation allowable value Nh. BL control area lighting change information is calculated.

  This BL control area lighting change information calculation method will be described with reference to the schematic diagram of FIG. Here, it is assumed that the four BL control areas A, B, C, and D shown in the BL control area lighting state 1041 in FIG. 4 are the BL control areas determined as the change target BL control areas.

  FIG. 9 shows a case where the BL control area is turned on based on the BL control area lighting information calculated by the local dimming control unit 101 and a case where the BL control area is turned on by changing the BL control area lighting information. It is a figure which shows the change of a lighting state and a luminance value.

FIGS. 9E, 9 </ b> K, and 9 </ b> Q show the BL control area lighting state (hereinafter referred to as the pre-change BL control area lighting state) based on the BL control area lighting information calculated by the local dimming control unit 101. FIG.
9 (f), (l), and (r) show the BL control area lighting state when the BL control area lighting information calculated by the local dimming control unit 101 is changed (hereinafter, the changed BL control area lighting state). It is a figure which shows.

First, the brightness value of the BL control area in the pre-change BL control area lighting state shown in FIG.
FIG. 9A shows the brightness value of the BL control area on the broken line 2031 in the pre-change BL control area lighting state shown in FIG.
FIG. 9C shows the brightness value of the BL control area on the broken line 2032 in the pre-change BL control area lighting state shown in FIG.

Next, changes in luminance values of the four change target BL control areas when the change target BL control area D in the upper right of the four change target BL control areas shown in FIG. calculate.
FIG. 9F is a diagram showing the changed BL control area lighting state when the upper right changing target BL control area D among the four changing target BL control areas is set to the non-lighting state.
FIG. 9B shows the brightness value of the BL control area on the broken line 2033 in the after-change BL control area lighting state shown in FIG.
FIG. 9D shows the brightness value of the BL control area on the broken line 2034 in the after-change BL control area lighting state shown in FIG.

  As shown in FIGS. 9B and 9D, when the changed BL control area lighting state is as shown in FIG. 9F, the change target BL control areas A and C before and after the change of the BL control area lighting state are changed. , And D change in luminance value exceeds the luminance fluctuation allowable value Nh.

  Therefore, the BL control area lighting calculation process shown below is performed, and the changed BL so that the change in the luminance value of the four change target BL control areas before and after the change in the BL control area lighting state is less than the luminance variation allowable value Nh. Determine the lighting status of the control area.

First, with respect to the BL control area lighting state shown in FIG. 9F, the BL control area lighting state is calculated by adding one BL control area to be lit.
FIG. 9 (l) shows the BL control area lighting in which the adjacent BL control area D ′ on the upper right BL control area D, which has been turned off in the BL control area lighting state shown in FIG. 9 (f), is turned on. Indicates the state.

When the pre-change BL control area lighting state shown in FIG. 9 (k) is changed to the post-change BL control area lighting state shown in FIG. 9 (l), the luminance values of the four change target BL control areas are changed. calculate.
FIG. 9 (h) shows the brightness value of the BL control area on the broken line 2037 in the after-change BL control area lighting state shown in FIG. 9 (l).
FIG. 9 (j) shows the brightness value of the BL control area on the broken line 2038 in the post-change BL control area lighting state shown in FIG. 9 (l).

  As shown in FIGS. 9H and 9J, when the changed BL control area lighting state is as shown in FIG. 9L, the luminance of the change target BL control area D before and after the change of the BL control area lighting state is changed. The change in value exceeds the luminance fluctuation allowable value Nh.

  Therefore, a BL control area lighting calculation process is further performed, and the changed BL control area so that the change in the luminance value of the four change target BL control areas before and after the change in the BL control area lighting state is less than the luminance fluctuation allowable value Nh. Find the lighting status.

Next, the BL control area lighting state in which one BL control area to be lit is added to the BL control area lighting state shown in FIG.
FIG. 9 (r) shows the BL control area in which the right adjacent BL control area D ″ of the right upper BL control area D in the non-lighted state in the BL control area lit state shown in FIG. 9 (l) is lit. Indicates the lighting state.

When the pre-change BL control area lighting state shown in FIG. 9 (q) is changed to the post-change BL control area lighting state shown in FIG. 9 (r), changes in luminance values of the four change target BL control areas are shown. calculate.
FIG. 9 (n) shows the brightness value of the BL control area on the broken line 2041 in the BL control area lighting state after change shown in FIG. 9 (r).
FIG. 9 (p) shows the luminance value of the BL control area on the broken line 2042 in the changed BL control area lighting state shown in FIG. 9 (r).

  As shown in FIGS. 9 (n) and 9 (p), when the changed BL control area lighting state is as shown in FIG. 9 (r), all four change target BL control areas before and after the change of the BL control area lighting state are all. The change in the luminance value is equal to or less than the luminance fluctuation allowable value Nh.

Therefore, by performing the stationary BL control area movement control so as to change the BL control area lighting state from FIG. 9 (q) to FIG. 9 (r), the change target BL control area before and after the change of the BL control area lighting state is performed. It is possible to make the change of the luminance value within an allowable range.
In this way, the post-change BL control area lighting state is determined such that the change in the luminance value of the change target BL control area before and after the change of the BL control area lighting state is equal to or less than the luminance variation allowable value Nh.
This completes the calculation of the BL control area lighting change information that allows the change target BL control area D to be in a non-lighting state and allows changes in the luminance values of all the change target BL control areas to be within the allowable range.

  The BL area diffusion movement control calculation unit 108 outputs the BL control area lighting change information calculated as described above to the LED control unit 104.

  The BL area diffusion movement control calculation unit 108 sets the change target BL control area to the non-lighting state for each of the four change target BL control areas, and keeps the change in the luminance value of all the change target BL control areas within the allowable range. BL control area lighting change information that can be calculated.

  10 and 11 show a case where the BL control area is turned on based on the BL control area lighting information calculated by the local dimming control unit 101 and a case where the BL control area is turned on by changing the BL control area lighting information. FIG. 6 is a diagram illustrating changes in lighting state and luminance value.

FIGS. 10E, 10K, 11Q, and 11W show the BL control area lighting state based on the BL control area lighting information calculated by the local dimming control unit 101 (before-change BL control area lighting state). FIG.
10 (f), (l), FIG. 11 (r), and (x) show the BL control area lighting state (changed BL control after change) when the BL control area lighting information calculated by the local dimming control unit 101 is changed. It is a figure which shows an area lighting state.

First, the case where the stationary BL control area movement control for turning off the upper right change target BL control area D among the four change target BL control areas is described.
The brightness value of the BL control area in the pre-change BL control area lighting state shown in FIG.
FIG. 10A is a broken line 20 in the pre-change BL control area lighting state shown in FIG.
The brightness value of the BL control area on 51 is shown.
FIG. 10C shows the luminance value of the BL control area on the broken line 2052 in the pre-change BL control area lighting state shown in FIG.

The brightness value of the BL control area in the after-change BL control area lighting state shown in FIG. The changed BL control area lighting state shown in FIG. 10F is the BL control realized by the BL control area lighting change information calculated by the BL area diffusion movement control calculation unit 108 through the calculation process as described in FIG. The area is on.
FIG.10 (b) shows the luminance value of the BL control area on the broken line 2053 in the BL control area lighting state after a change shown in FIG.10 (f).
FIG.10 (d) shows the luminance value of the BL control area on the broken line 2054 in the BL control area lighting state after a change shown in FIG.10 (f).

As shown in FIGS. 10B and 10D, when the changed BL control area lighting state is as shown in FIG. 10F, all four change target BL control areas before and after the change of the BL control area lighting state are all performed. The change in the luminance value is equal to or less than the luminance fluctuation allowable value Nh.
Therefore, when the change target BL control area D is turned off, the stationary BL control area movement control is performed so as to change the BL control area lighting state from FIG. 10 (e) to FIG. 10 (f). Thereby, the change of the luminance value of the change target BL control area before and after the change of the BL control area lighting state can be set within the allowable range.

Next, the case where the stationary BL control area movement control for turning off the lower right change target BL control area A among the four change target BL control areas is described.
The brightness value of the BL control area in the pre-change BL control area lighting state shown in FIG. 10 (k) is calculated.
FIG. 10G shows the brightness value of the BL control area on the broken line 2055 in the pre-change BL control area lighting state shown in FIG.
FIG. 10 (i) shows the brightness value of the BL control area on the broken line 2056 in the pre-change BL control area lighting state shown in FIG. 10 (k).

The brightness value of the BL control area in the after-change BL control area lighting state shown in FIG. The changed BL control area lighting state shown in FIG. 10 (l) is realized by the BL control area lighting change information calculated by the BL area diffusion movement control calculation unit 108 through the calculation process as described in FIG. The area is on.
FIG. 10H shows the brightness value of the BL control area on the broken line 2057 in the post-change BL control area lighting state shown in FIG.
FIG. 10 (j) shows the brightness value of the BL control area on the broken line 2058 in the after-change BL control area lighting state shown in FIG. 10 (l).

As shown in FIGS. 10H and 10J, when the changed BL control area lighting state is as shown in FIG. 10L, all four change target BL control areas before and after the change of the BL control area lighting state are obtained. The change in the luminance value is equal to or less than the luminance fluctuation allowable value Nh.
Therefore, when the change target BL control area A is turned off, the stationary BL control area movement control is performed so as to change the BL control area lighting state from FIG. 10 (k) to FIG. 10 (l). Thereby, the change of the luminance value of the change target BL control area before and after the change of the BL control area lighting state can be set within the allowable range.

Next, the case where the stationary BL control area movement control for turning off the lower left change target BL control area B among the four change target BL control areas is described.
The brightness value of the BL control area in the pre-change BL control area lighting state shown in FIG. 11 (q) is calculated.
FIG. 11 (m) shows the brightness value of the BL control area on the broken line 2059 in the pre-change BL control area lighting state shown in FIG. 11 (q).
FIG. 11 (o) shows the brightness value of the BL control area on the broken line 2060 in the pre-change BL control area lighting state shown in FIG. 11 (q).

The brightness value of the BL control area in the after-change BL control area lighting state shown in FIG. The post-change BL control area lighting state shown in FIG. 11 (r) is the BL control realized by the BL control area lighting change information calculated by the BL area diffusion movement control calculation unit 108 through the calculation process described in FIG. The area is on.
FIG. 11 (n) shows the brightness value of the BL control area on the broken line 2061 in the BL control area lighting state after change shown in FIG. 11 (r).
FIG.11 (p) shows the luminance value of the BL control area on the broken line 2062 in the BL control area lighting state after a change shown in FIG.11 (r).

As shown in FIGS. 11 (n) and 11 (p), when the changed BL control area lighting state is as shown in FIG. 11 (r), all four change target BL control areas before and after the change of the BL control area lighting state are all. The change in the luminance value is equal to or less than the luminance fluctuation allowable value Nh.
Therefore, when the change target BL control area B is turned off, the stationary BL control area movement control is performed so as to change the BL control area lighting state from FIG. 11 (q) to FIG. 11 (r). Thereby, the change of the luminance value of the change target BL control area before and after the change of the BL control area lighting state can be set within the allowable range.

Next, the case where the stationary BL control area movement control for turning off the lower left change target BL control area C among the four change target BL control areas is described.
The brightness value of the BL control area in the pre-change BL control area lighting state shown in FIG.
FIG. 11S shows the luminance value of the BL control area on the broken line 2063 in the pre-change BL control area lighting state shown in FIG.
FIG. 11 (u) shows the brightness value of the BL control area on the broken line 2064 in the pre-change BL control area lighting state shown in FIG. 11 (w).

The brightness value of the BL control area in the BL control area lighting state after change shown in FIG. The BL control area lighting state after the change shown in FIG. 11 (x) is realized by the BL control area lighting change information calculated by the BL area diffusion movement control calculation unit 108 through the calculation process as described in FIG. The area is on.
FIG. 11 (t) shows the brightness value of the BL control area on the broken line 2065 in the after-change BL control area lighting state shown in FIG. 11 (x).
FIG. 11 (v) shows the brightness value of the BL control area on the broken line 2066 in the post-change BL control area lighting state shown in FIG. 11 (x).

As shown in FIGS. 11 (t) and 11 (v), when the changed BL control area lighting state is as shown in FIG. 11 (x), all four change target BL control areas before and after the change of the BL control area lighting state are all. The change in the luminance value is equal to or less than the luminance fluctuation allowable value Nh.
Therefore, when the change target BL control area C is turned off, the stationary BL control area movement control is performed so as to change the BL control area lighting state from FIG. 11 (w) to FIG. 11 (x). Thereby, the change of the luminance value of the change target BL control area before and after the change of the BL control area lighting state can be set within the allowable range.

The BL area diffusion movement control calculation unit 108 changes the BL control areas A, B, C, and D to be changed.
BL control area lighting change information when each of these is turned off is calculated so that the BL control area lighting state after the change is as shown in FIG. 10 (l), FIG. 11 (r), (x), and FIG. 10 (f). To do.
By performing stationary BL control area movement control based on the BL control area lighting change information calculated in this way, the variation in the luminance deterioration of the LED light is reduced while the change in the brightness of the change target BL control area is kept within an allowable range. It becomes possible to do.

  The image display apparatus 2 according to the second embodiment detects a stationary BL control area in which the luminance control value is less likely to change and the luminance deterioration variation is likely to occur based on the change in the luminance control value for each BL control area. Then, by setting the detected brightness control value of the stationary BL control area as the brightness control value of the adjacent BL control area, the brightness control value of the stationary BL control area is moved to the adjacent BL control area. As a result, since the luminance degradation between the stationary BL control area and the adjacent BL control area is averaged, it is possible to reduce the occurrence of variations in the luminance degradation of the LED lights. Further, although the detected brightness control value of the stationary BL control area is changed, the adjacent BL control area emits light with the brightness control value initially set in the stationary BL control area, so that it corresponds to the stationary BL control area. It is possible to suppress a change in display brightness of an image (still area) in the display area. Therefore, it is possible to suppress a sense of incongruity in the appearance of the image including the still region.

  The changed BL control area lighting state is not limited to the examples of FIGS. 10 and 11 described above. If the changed BL control area lighting state is such that the change in the brightness value of the change target BL control area before and after the change of the BL control area lighting state is less than the luminance fluctuation allowable value Nh, the same effect as in the present embodiment is obtained. Play.

101 local dimming control unit, 102 stationary BL control area detection unit, 103 BL area movement control calculation unit, 104 LED control unit, 105 LED unit, 106 display unit

Claims (9)

A backlight having a plurality of LED lights;
A display panel having a plurality of pixels that change the transmittance of light from the backlight;
And the backlight is an image display device configured by arranging one or more LED lights corresponding to each of a plurality of divided areas dividing the display area of the display panel,
A setting means for setting a light emission luminance value of the LED light for each of the divided regions in accordance with an input video signal;
Based on the history of the light emission luminance value of the LED light for each of the divided regions set by the setting means, the divided region corresponding to the LED light in which the variation range of the light emission luminance value is not more than a predetermined threshold value continues for a predetermined period or longer. Detecting means for detecting a still divided region,
The light emission luminance value of the LED light in the stationary divided region is changed to a light emission luminance value that is different from the light emission luminance value set by the setting means for the LED light in the stationary divided region to be larger than the threshold value. The light emission luminance value of the LED light of the divided region adjacent to the region and not detected as the stationary divided region by the detection unit is set to the light emission luminance value set by the setting unit for the LED light of the stationary divided region. Change means to change;
When a stationary divided area is detected by the detecting means, the LED light of the stationary divided area and the adjacent divided area is caused to emit light with the light emission luminance value changed by the changing means, and the LEDs of the other divided areas are Light emission control means for emitting light at a light emission luminance value set by the setting means;
An image display apparatus.   The changing means has a light emission luminance value set for the LED light in the stationary divided area among the stationary divided areas detected by the detecting means that is equal to or greater than a predetermined brightness determination value and the LED light in the stationary divided area. LED light in a still divided region that satisfies the condition that the difference between the light emission luminance value set in the LED and the light emission luminance value set in the LED light in the divided region adjacent to the still divided region is equal to or greater than a predetermined adjacent luminance difference determination value The image display apparatus according to claim 1, wherein the light emission luminance value of the image is changed.   The image display device according to claim 2, wherein the changing unit changes a light emission luminance value of the LED light in the still divided region so that the LED light in the still divided region that satisfies the condition is turned off. Having a calculation means for calculating the luminance value for each divided region in consideration of the influence on the luminance value of the other divided region due to the light emission of the LED light of a certain divided region being diffused to the other divided region;
The changing means includes the brightness value of the still divided area calculated by the calculating means based on the light emission luminance value of the LED light of each divided area set by the setting means, and the static divided area and the adjacent divided areas. The difference between the brightness value of the stationary divided area calculated by the calculation means based on the light emission brightness value of the LED light in each divided area when the light emission brightness value of the LED light is changed is equal to or less than a predetermined allowable value. 4. The image display device according to claim 1, wherein a light emission luminance value after the change of the still divided area and the divided areas adjacent thereto is determined. 5.   When there are a plurality of still divided areas detected by the detecting means, the changing means changes the light emission luminance value only for the LED light corresponding to any one of the plurality of still divided areas, and the light emission luminance. 5. The image display device according to claim 1, wherein the still divided areas corresponding to the LED lights whose values are to be changed are sequentially changed one by one among the plurality. 6. When there are a plurality of still divided areas detected by the detecting means, the changing means changes the emission luminance value only for LED lights corresponding to a still divided area group consisting of a part of the plurality of still divided areas. In addition, the still divided region group corresponding to the LED light whose light emission luminance value is to be changed is sequentially changed one by one from among the plurality of still divided region groups that can be defined based on the plurality of still divided regions. The image display apparatus of any one of Claim 1 to 4.   The detection unit stores the information on the emission luminance value for each divided region set by the setting unit at a predetermined time interval, and each time the emission luminance value is stored, the stored information on the emission luminance value is stored in the previous time. The image display device according to any one of claims 1 to 6, wherein a fluctuation range of the light emission luminance value is acquired for each divided region by comparing with the stored information of the light emission luminance value.   The detection unit stores information on the emission luminance value for each divided region set by the setting unit at a predetermined time interval, and reads and reads information on the emission luminance value at which the stored time is separated by a predetermined time. The image display device according to claim 1, wherein the fluctuation range of the emission luminance value is acquired for each divided region by comparing the information of the emission luminance value. A backlight having a plurality of LED lights;
A display panel having a plurality of pixels that change the transmittance of light from the backlight;
And the backlight is a method of controlling an image display device in which one or more LED lights are arranged corresponding to each of a plurality of divided areas dividing the display area of the display panel. ,
A setting step for setting a light emission luminance value of the LED light for each of the divided regions according to an input video signal;
Based on the history of the light emission luminance value of the LED light for each of the divided regions set in the setting step, the divided region corresponding to the LED light in which the variation range of the light emission luminance value is equal to or less than a predetermined threshold continues for a predetermined period or more. A detection step of detecting a stationary divided region,
The light emission luminance value of the LED light in the stationary divided region is changed to a light emission luminance value in which the difference from the light emission luminance value set in the LED light of the stationary divided region in the setting step is larger than the threshold, and the stationary division is performed. The light emission luminance value of the LED light of the divided region adjacent to the region and not detected as the stationary divided region by the detection step is set to the light emission luminance value set for the LED light of the stationary divided region in the setting step. Change process to change,
When a stationary divided region is detected by the detection step, the LED light of the stationary divided region and the adjacent divided region is caused to emit light with the light emission luminance value changed by the changing step, and the LEDs of the other divided regions A light emission control step of causing the light to emit light at the light emission luminance value set by the setting step;
A method for controlling an image display apparatus having

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