JP5183240B2 - Image display device and image display method - Google Patents

Description

  The present invention relates to an image display device, and more particularly to an image display device having a function of controlling the brightness of a backlight (backlight dimming function).

  In an image display device equipped with a backlight such as a liquid crystal display device, the power consumption of the backlight can be suppressed and the image quality of the display image can be improved by controlling the luminance of the backlight based on the input image. In particular, by dividing the screen into a plurality of areas and controlling the luminance of the backlight light source corresponding to the area based on the input image in the area, it is possible to further reduce power consumption and improve image quality. Hereinafter, such a method of driving the display panel while controlling the luminance of the backlight light source based on the input image in the area is referred to as “area active driving”.

  In a liquid crystal display device that performs area active drive, for example, RGB three-color LEDs (Light Emitting Diodes) or white LEDs are used as a backlight light source. The luminance of the LED corresponding to each area is obtained based on the maximum value or the average value of the luminance of the pixels in each area, and is given as LED data to the backlight driving circuit. Further, display data (data for controlling the light transmittance of the liquid crystal) is generated based on the LED data and the input image, and the display data is supplied to a driving circuit for the liquid crystal panel.

  According to the liquid crystal display device as described above, suitable display data and LED data are obtained based on the input image, the light transmittance of the liquid crystal is controlled based on the display data, and the LED corresponding to each area based on the LED data. By controlling the brightness of the input image, the input image can be displayed on the liquid crystal panel. When the luminance of the pixels in the area is small, the power consumption of the backlight can be reduced by decreasing the luminance of the LED corresponding to the area.

The following prior art documents are known in relation to the present invention. Japanese Patent Application Laid-Open No. 2001-142409 discloses an invention of a video display device that drives and controls an LED in units of divided areas so that illumination light is irradiated only to a screen area where illumination light is required at least according to a video signal. Has been. Japanese Patent Laid-Open No. 2005-258403 discloses a luminance distribution calculating unit that determines the brightness of illumination light for each region based on an image signal, and controls the illumination light for each region based on the determination of the luminance distribution calculating unit. An invention of an image display device is disclosed that includes a backlight control means to reduce power consumption. Japanese Patent Application Laid-Open No. 2007-34251 discloses correction for each pixel of the display unit based on a deviation amount between the light emission luminance of each light source arranged corresponding to each divided region and the optimum value of the display luminance in each unit of the display screen. An invention of a display device that calculates an amount and generates a display drive signal based on the correction amount is disclosed.
JP 2001-142409 A JP 2005-258403 A JP 2007-34251 A

However, in the above-described image display device that performs area active drive, when attention is paid to a certain area, only the LED in the area is lit (hereinafter referred to as “single area lighting”) in all areas. Sometimes the brightness that appears in the area and the brightness that appears in the area when the LEDs of all the areas are lit (hereinafter referred to as “all area lighting”) are greatly different, and correct gradation display is not performed. This will be described with reference to FIG. As shown in FIG. 33A, it is assumed that the luminance appearing in the area when only the LED in the area located at the center of the screen is lit is 50 cd / m ² . At this time, when the entire area is lit as shown in FIG. 33B, for example, a luminance of 500 cd / m ² appears in the area. This is because light emitted from an LED in a certain area irradiates not only the area but also the surrounding area. Conversely, only light emitted from the LED in the area is included in a certain area. This is because the light emitted from the LEDs in the surrounding area is also irradiated. In the example shown in FIG. 33 (b), not only the light emitted from the LED in the area but also the light emitted from the LED in the area indicated by the dotted line is irradiated to the area located at the center of the screen. . On the other hand, in the example shown in FIG. 33 (a), only the light emitted from the LED in the area is irradiated to the area located at the center of the screen. In this way, the luminance (peak luminance) when the single area is lit is about one tenth of the luminance when the entire area is lit, and a desired gradation display is not performed when the single area is lit. For example, when an image representing “a state in which only one star is shining in the night sky” is displayed, a state in which the stars are brightly shining (a feeling of glitter) does not sufficiently appear on the screen. A state where the peak luminance is so low that the desired gradation display is not performed is hereinafter referred to as “peak luminance shortage”.

  Further, in the above-described image display device that performs area active drive, when moving image display is performed, the maximum value of the luminance of the pixels in the area changes for each frame, and the luminance of the LED changes for each frame. , Flicker may occur on the screen. This flicker becomes more prominent when the screen is darker than when the screen is bright. Hereinafter, the flicker will be described. For example, as shown in FIG. 34, consider a case where a moving image in which a white (luminance 100%) bar 92 having a predetermined width moves to the left in a black (luminance 0%) background is displayed. In this case, the maximum luminance value of the pixels in the area 91 increases from 0% to 100% as soon as a part of the bar 92 enters the area 91. For this reason, if the luminance of the LED is determined based on the maximum luminance value of the pixels in each area, the luminance of the LED corresponding to the area 91 changes rapidly from the minimum luminance to the maximum luminance. . As a result, a large flicker occurs on the screen. In order to suppress the occurrence of such flicker, a method for determining the luminance of the LED based on the average value of the luminance of the pixels in the area is also known conventionally. The contrast when displaying a still image is insufficient.

  SUMMARY OF THE INVENTION An object of the present invention is to eliminate a lack of brightness when a single area is lit in an image display device that performs area active driving. Another object of the present invention is to suppress the occurrence of flicker during moving image display without reducing the contrast during still image display in an image display device that performs area active drive.

A first invention is an image display device having a function of controlling the brightness of a backlight,
A display panel including a plurality of display elements;
A backlight including a plurality of light sources;
A light emission luminance calculation unit that divides the input image into a plurality of areas and obtains the luminance at the time of light emission of the light source corresponding to each area as the first light emission luminance based on the input image corresponding to each area;
A light emission luminance correction unit for obtaining a second light emission luminance by correcting the first light emission luminance based on predetermined correction data, and outputting data indicating the second light emission luminance as light emission luminance control data;
A display data calculation unit for obtaining display data for controlling the light transmittance of the display element based on the input image and the light emission luminance control data;
A panel drive circuit that outputs a signal for controlling the light transmittance of the display element to the display panel based on the display data;
A backlight driving circuit that outputs a signal for controlling the luminance of the light source to the backlight based on the emission luminance control data;
A correction filter that stores the correction data for one area and a plurality of predetermined areas around the area;
When the correction filter defines an arbitrary area as a target area, the correction filter determines the brightness at which the light source emits light in a plurality of predetermined areas around the target area according to the first light emission luminance of the target area. Is stored as the correction data,
The light emission luminance correction unit is
By applying the correction filter to each area, the first emission luminance for a plurality of predetermined areas centered on each area is obtained based on the correction data stored in the applied correction filter. Correct ,
The sum of the luminance for each area obtained as a result of applying the correction filter to the plurality of areas is set as the second emission luminance of each area .

According to a second invention, in the first invention,
The light emission luminance correction unit is configured such that the second light emission luminance is higher than the first light emission luminance for a plurality of predetermined areas except for the area centered on the area where the first light emission luminance is not zero. The first light emission luminance for the plurality of predetermined areas is corrected.

According to a third invention, in the first invention,
A plurality of different correction filters are provided,
The light emission luminance correction unit applies any one of the plurality of correction filters for each area.

According to a fourth invention, in the third invention,
It further includes a mode selection unit that accepts an external mode selection,
The light emission luminance correction unit is configured to select a correction filter to be applied when correcting the first light emission luminance based on the mode received by the mode selection unit.

A fifth invention is the fourth invention,
A first correction filter and a second correction filter as the plurality of correction filters;
The first mode and the second mode are provided as modes that can be selected from the outside,
Regarding the data value of the correction data for each area stored in the correction filter, the rate of change of the data value when the area of interest moves from the center to the outside is defined as the data value change rate. Correction for the first correction filter and the second correction filter so that the data value change rate for the second correction filter is larger than the data value change rate for the first correction filter. Data is stored,
If the mode received by the mode selection unit is the first mode, the light emission luminance correction unit selects the first correction filter when correcting the first light emission luminance, and the mode If the mode received by the selection unit is the second mode, the second correction filter is selected when correcting the first light emission luminance.

According to a sixth invention, in the third invention,
Based on the input image, further comprises an image determination unit for determining whether each area is a moving image or a still image,
The light emission luminance correction unit selects a correction filter to be applied when correcting the first light emission luminance for each area based on a determination result by the image determination unit.

A seventh invention is the sixth invention, wherein
A first correction filter and a second correction filter as the plurality of correction filters;
Regarding the data value of the correction data for each area stored in the correction filter, the rate of change of the data value when the area of interest moves from the center to the outside is defined as the data value change rate. Correction for the first correction filter and the second correction filter so that the data value change rate for the second correction filter is larger than the data value change rate for the first correction filter. Data is stored,
The light emission luminance correction unit selects the first correction filter when correcting the first light emission luminance for the area determined to be a moving image by the image determination unit, and the image determination unit For the area determined to be a still image, the second correction filter is selected when the first light emission luminance is corrected.

In an eighth aspect based on the seventh aspect ,
One or more correction filters such that the rate of change of the data value is larger than the first correction filter and smaller than the second correction filter;
A variable value changing unit that changes a value of a predetermined variable according to a determination result by the image determining unit;
The light emission luminance correction unit selects a correction filter to be applied when correcting the first light emission luminance based on a value of the predetermined variable.

According to a ninth invention, in any one of the sixth to eighth inventions,
When the luminance that can be displayed in an area to which the correction filter is applied is defined as display luminance, any of the plurality of correction filters is applied to each area. However, correction data is stored in the plurality of correction filters so that the display luminance is constant.

In a tenth aspect based on the third aspect ,
A moving image rate that determines whether each area is a moving image or a still image based on the input image, and calculates a ratio of the number of areas determined to be moving images to the number of the plurality of areas as a screen moving image rate A calculation unit;
The light emission luminance correction unit selects a correction filter to be applied when correcting the first light emission luminance based on the screen moving image rate.

In an eleventh aspect based on the third aspect ,
An average luminance calculating unit for calculating an average luminance of the input image for one screen;
The emission luminance correction unit selects a correction filter to be applied when correcting the first emission luminance based on the average luminance calculated by the average luminance calculation unit.

A twelfth invention is an image display method in an image display device comprising a display panel including a plurality of display elements and a backlight including a plurality of light sources,
A light emission luminance calculating step of dividing the input image into a plurality of areas and obtaining the light emission luminance of the light source corresponding to each area as the first light emission luminance based on the input image corresponding to each area;
A light emission luminance correction step of obtaining a second light emission luminance by correcting the first light emission luminance based on predetermined correction data, and outputting data indicating the second light emission luminance as light emission luminance control data;
A display data calculation step for obtaining display data for controlling the light transmittance of the display element based on the input image and the light emission luminance control data;
A panel driving step for outputting a signal for controlling the light transmittance of the display element to the display panel based on the display data;
A backlight driving step for outputting a signal for controlling the luminance of the light source to the backlight based on the emission luminance control data;
The image display device includes a correction filter that stores the correction data for one area and a plurality of predetermined areas around the area.
When the correction filter defines an arbitrary area as a target area, the correction filter determines the brightness at which the light source emits light in a plurality of predetermined areas around the target area according to the first light emission luminance of the target area. Is stored as the correction data,
In the light emission luminance correction step,
By applying the correction filter for each area, the first emission luminance for a plurality of predetermined areas centered on each area is based on the correction data stored in the applied correction filter. Corrected ,
The sum of the luminance for each area obtained as a result of applying the correction filter to the plurality of areas is the second emission luminance of each area .

Moreover, the modification grasped | ascertained by referring embodiment and drawing in 12th invention is considered as a means for solving a subject.

According to the first invention, in the image display device that controls the luminance of the light source for each area, after the luminance at the time of light emission of the light source in each area (first emission luminance) is obtained based on the input image, The first emission luminance is corrected based on the correction data stored in the correction filter. Then, the luminance of the light source in each area is controlled based on the emission luminance control data indicating the corrected luminance (second emission luminance). For this reason, by providing a correction filter that stores correction data corresponding to various display defects in advance, each light source can emit light at a luminance different from the luminance based on the input image, and display defects occur. It is suppressed.

  According to the second aspect, when the light source of a certain area is turned on based on the input image, the brightness of the area around the area is increased. For this reason, when single area lighting is performed (hereinafter, an area to be lit is referred to as a “lighting target area”), light sources in areas around the lighting target area are also lit. As a result, the lighting target area is also irradiated with light from the surrounding area, and the display luminance of the lighting target area is increased as compared with the conventional case. Thereby, the lack of luminance at the time of lighting a single area is solved.

According to the third aspect , a plurality of correction filters are prepared in advance. For this reason, the occurrence of display defects is effectively suppressed by applying a suitable correction filter based on various conditions and the like.

According to the fourth aspect of the invention, a correction filter to be applied when correcting the first light emission luminance is selected from a plurality of correction filters prepared in advance according to a mode selected from the outside. . Thereby, the correction suitable for the luminance of the light source in each area is performed according to the mode selected by the user. For this reason, suitable image display is performed for each mode.

According to the fifth aspect of the invention, the first correction filter having a relatively low data value change rate and the second correction filter having a relatively high data value change rate are prepared in advance, and the mode is selected from the outside. One of the correction filters is selected according to the above. For this reason, an image display with increased overall brightness and an image display with increased contrast are switched according to the mode selected by the user.

According to the sixth aspect of the invention, it is determined whether each area is a moving image or a still image, and the correction filter applied when correcting the first light emission luminance based on the determination result. Selected. For this reason, by providing in advance a correction filter suitable for moving image display and a correction filter suitable for still image display, for example, it is possible to suppress the occurrence of flicker during moving image display, or during still image display. High contrast and low power consumption can be achieved.

According to the seventh aspect , for the area determined to be a moving image by the image determination unit, the first light emission luminance is corrected based on the correction filter having a relatively low data value change rate, and the image determination unit For the area determined to be a still image, the first emission luminance is corrected based on a correction filter with a relatively high data value change rate. For this reason, when a single area lighting is performed, if a moving image display is performed in the lighting target area, the second emission luminance in the area around the lighting target area is set to a relatively high luminance, and the lighting target area If still image display is performed, the second emission luminance of the area around the lighting target area is set to a relatively low luminance. As a result, the luminance difference between the areas at the time of moving image display becomes smaller than before, and the occurrence of flicker is suppressed. Further, when displaying a still image, an increase in power consumption is suppressed and a high contrast can be obtained.

According to the eighth aspect of the invention, the correction filter for the data value change rate intermediate between the first correction filter and the second correction filter is prepared in advance. Then, a correction variable is applied when the value of a predetermined variable is changed according to the determination of whether the image is a moving image or a still image, and the first emission luminance is corrected based on the value of the variable. Is selected. For this reason, when there is a change from a moving image to a still image or a change from a still image to a moving image, the characteristics of the correction filter gradually change without sudden change. Thereby, the change from the moving image display to the still image display or the change from the still image display to the moving image display is performed without giving a sense of incongruity to human eyes.

According to the ninth aspect, the display brightness obtained by the correction is constant regardless of which of the plurality of correction filters prepared in advance is applied when the correction filter corrects the first light emission brightness. It becomes. For this reason, a change from a moving image display to a still image display or a change from a still image display to a moving image display is performed without giving a sense of incongruity to human eyes.

According to the tenth aspect of the present invention, it is determined whether each area is a moving image or a still image, and when the first emission luminance is corrected based on the ratio of the number of moving image areas to the total number of areas. A correction filter to be applied is selected. For this reason, by providing in advance a correction filter suitable for moving image display and a correction filter suitable for still image display, for example, it is possible to suppress the occurrence of flicker during moving image display, or during still image display. High contrast and low power consumption can be achieved.

According to the eleventh aspect , the correction filter to be applied when correcting the first light emission luminance is selected based on the average luminance of the input image. For this reason, by providing in advance a correction filter suitable for when the screen is generally bright and a correction filter suitable for when the screen is generally dark, according to the overall brightness of the input image. Therefore, it is possible to make a correction suitable for the luminance of the light source in each area.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

<1. First Embodiment>
<1.1 Overall configuration and operation overview>
FIG. 2 is a block diagram showing a configuration of the liquid crystal display device 10 according to the first embodiment of the present invention. The liquid crystal display device 10 illustrated in FIG. 2 includes a liquid crystal panel 11, a panel drive circuit 12, a backlight 13, a backlight drive circuit 14, and an area active drive processing unit 15. The liquid crystal display device 10 divides the screen into a plurality of areas, and performs area active driving for driving the liquid crystal panel 11 while controlling the luminance of the backlight light source based on the input image in the area. Hereinafter, it is assumed that m and n are integers of 2 or more, p and q are integers of 1 or more, and at least one of p and q is an integer of 2 or more.

  An input image 31 including an R image, a G image, and a B image is input to the liquid crystal display device 10. Each of the R image, the G image, and the B image includes the luminance of (m × n) pixels. Based on the input image 31, the area active drive processing unit 15 displays data for use in driving the liquid crystal panel 11 (hereinafter referred to as liquid crystal data 32) and light emission luminance control data for use in driving the backlight 13 (hereinafter referred to as LED data). 33) (details will be described later).

  The liquid crystal panel 11 includes (m × n × 3) display elements 21. The display elements 21 are arranged two-dimensionally as a whole, 3 m in the row direction (horizontal direction in FIG. 2) and n in the column direction (vertical direction in FIG. 2). The display element 21 includes an R display element that transmits red light, a G display element that transmits green light, and a B display element that transmits blue light. The R display element, the G display element, and the B display element are arranged side by side in the row direction, and three pixels form one pixel.

  The panel drive circuit 12 is a drive circuit for the liquid crystal panel 11. The panel drive circuit 12 outputs a signal (voltage signal) for controlling the light transmittance of the display element 21 to the liquid crystal panel 11 based on the liquid crystal data 32 output from the area active drive processing unit 15. The voltage output from the panel drive circuit 12 is written to a pixel electrode (not shown) in the display element 21, and the light transmittance of the display element 21 changes according to the voltage written to the pixel electrode.

  The backlight 13 is provided on the back side of the liquid crystal panel 11 and irradiates the back surface of the liquid crystal panel 11 with backlight light. FIG. 3 is a diagram showing details of the backlight 13. As illustrated in FIG. 3, the backlight 13 includes (p × q) LED units 22. The LED units 22 are two-dimensionally arranged as a whole, p in the row direction and q in the column direction. The LED unit 22 includes one red LED 23, one green LED 24, and one blue LED 25. Light emitted from the three LEDs 23 to 25 included in one LED unit 22 strikes a part of the back surface of the liquid crystal panel 11.

  The backlight drive circuit 14 is a drive circuit for the backlight 13. The backlight drive circuit 14 outputs a signal (voltage signal or current signal) for controlling the luminance of the LEDs 23 to 25 to the backlight 13 based on the LED data 33 output from the area active drive processing unit 15. The brightness of the LEDs 23 to 25 is controlled independently of the brightness of the LEDs inside and outside the unit.

  The screen of the liquid crystal display device 10 is divided into (p × q) areas, and one LED unit 22 is associated with one area. For each of the (p × q) areas, the area active drive processing unit 15 obtains the luminance (luminance during light emission) of the red LED 23 corresponding to the area based on the R image in the area. Similarly, the luminance of the green LED 24 is determined based on the G image in the area, and the luminance of the blue LED 25 is determined based on the B image in the area. The area active drive processing unit 15 calculates the luminance of all the LEDs 23 to 25 included in the backlight 13 and outputs LED data 33 representing the calculated luminance to the backlight driving circuit 14.

  Further, the area active drive processing unit 15 obtains the luminance of the backlight light (displayable luminance, hereinafter referred to as “display luminance”) in all the display elements 21 included in the liquid crystal panel 11 based on the LED data 33. Further, the area active drive processing unit 15 obtains the light transmittance of all the display elements 21 included in the liquid crystal panel 11 based on the input image 31 and the display luminance, and displays the liquid crystal data 32 representing the obtained light transmittance on the panel. Output to the drive circuit 12.

  In the liquid crystal display device 10, the luminance of the R display element is the product of the luminance of the red light emitted from the backlight 13 and the light transmittance of the R display element. The light emitted from one red LED 23 hits a plurality of areas around the corresponding one area. Accordingly, the luminance of the R display element is the product of the total luminance of the light emitted from the plurality of red LEDs 23 and the light transmittance of the R display element. Similarly, the luminance of the G display element is the product of the total luminance of light emitted from the plurality of green LEDs 24 and the light transmittance of the G display element, and the luminance of the B display element is emitted from the plurality of blue LEDs 25. This is the product of the total light luminance and the light transmittance of the B display element.

  According to the liquid crystal display device 10 configured as described above, suitable liquid crystal data 32 and LED data 33 are obtained based on the input image 31, the light transmittance of the display element 21 is controlled based on the liquid crystal data 32, and the LED data By controlling the luminance of the LEDs 23 to 25 based on 33, the input image 31 can be displayed on the liquid crystal panel 11. Further, when the luminance of the pixels in the area is small, the power consumption of the backlight 13 can be reduced by reducing the luminance of the LEDs 23 to 25 corresponding to the area. Further, when the luminance of the pixels in the area is small, the luminance of the display element 21 corresponding to the area is switched between a smaller number of levels, so that the resolution of the image can be increased and the image quality of the display image can be improved.

<1.2 Configuration of Area Active Drive Processing Unit>
FIG. 1 is a block diagram showing a detailed configuration of the area active drive processing unit 15 in the present embodiment. The area active drive processing unit 15 includes a light emission luminance calculation unit 151, a light emission luminance correction unit 152, a display luminance calculation unit 153, and a liquid crystal data calculation unit 154 as components for executing predetermined processing. The LED filter 155 is provided as a component for storing. In the present embodiment, a display data calculation unit is realized by the display luminance calculation unit 153 and the liquid crystal data calculation unit 154, and a correction filter is realized by the LED filter 155.

  The light emission luminance calculation unit 151 divides the input image 31 into a plurality of areas, and obtains the luminance at the time of light emission of the LED corresponding to each area based on the input image 31. As a method of obtaining the luminance, for example, a method of determining based on the maximum luminance value Ma of the pixels in the area, a method of determining based on the average luminance Me of the pixels in the area, and the luminance of the pixels in the area There is a method of determining based on a value obtained by weighted averaging the maximum value Ma and the average value Me. The luminance obtained by the light emission luminance calculation unit 151 is hereinafter referred to as “first light emission luminance”.

  The LED filter 155 stores data for correcting the first light emission luminance 34 obtained by the light emission luminance calculation unit 151. In the present embodiment, the LED filter 155 is as shown in FIG. The LED filter 155 assumes that the brightness of a certain area (first emission brightness) is “100” and the brightness of other areas (first emission brightness) is “0”. In addition, a value indicating at which luminance the LED for 25 areas centering on the area is caused to emit light is stored. For example, when only the area indicated by reference numeral 61 in FIG. 4 is lit based on the input image 31, the LED of the area indicated by reference numeral 62 is caused to emit light having a luminance of 80/100 of the luminance of the lighting target area. In addition, the LED in the area indicated by reference numeral 63 is caused to emit light with a luminance of 10/100 of the luminance of the lighting target area. In the following, the value (filter coefficient) stored in the LED filter 155 is referred to as “correction data”. In the present embodiment, the LED filter 155 stores correction data for 25 areas (5 areas in the vertical direction × 5 areas in the horizontal direction), but the present invention is not limited to this. For example, correction data for 49 areas (7 areas in the vertical direction × 7 areas in the horizontal direction) may be stored in the LED filter 155.

  The light emission luminance correction unit 152 corrects the first light emission luminance 34 obtained by the light emission luminance calculation unit 151 based on the correction data 35 stored in the LED filter 155. This correction will be described with reference to FIGS. The correction is performed by applying the LED filter 155 as shown in FIG. 4 for each area. For example, assuming that the screen is divided into a plurality of areas as shown in FIG. 5, first, the LED filter 155 is applied to the area A (1, 1). Thereby, in response to the LEDs in the area A (1,1) emitting light, it is required to determine the brightness at which the LEDs in the area around the area A (1,1) emit light. Next, the LED filter 155 is applied to the area A (2, 1). Thereby, in response to the LEDs in the area A (2, 1) emitting light, it is required to determine the brightness at which the LEDs in the area around the area A (2, 1) emit light. Similarly, the LED filter 155 is applied for each remaining area in the first row. Further, the LED filter 155 is applied to each area from the second row in a similar manner. As described above, the LED filter 155 is applied to each area one by one.

  Incidentally, a plurality of LED filters 155 may be provided in advance as shown in FIG. And, for example, “the third LED filter is applied to the area A (1,1), the first LED filter is applied to the area A (2,1),” and so on. A different LED filter may be applied to each area.

  When the LED filter 155 is applied to all areas as described above, the luminance for each area is determined by obtaining the sum of the values (luminance values) obtained as a result (sum for each area). The The luminance determined in this way is the luminance after correction of the first light emission luminance 34 (hereinafter referred to as “second light emission luminance”).

  By correcting the first light emission luminance 34, for example, in the case of conventional single area lighting as shown in FIG. 7A, as shown in FIG. 7B, The LEDs are also turned on in the area around the area where the LEDs should be turned on. The process of correcting the luminance of the area around the area where the LED should be lit by applying the LED filter to each area is hereinafter referred to as “LEDBLUR process”.

  Data indicating the second light emission luminance obtained by the light emission luminance correction unit 152 is provided to the backlight drive circuit 14 as the LED data 33 and also to the display luminance calculation unit 153. The display brightness calculation unit 153 obtains the display brightness 36 in all the display elements 21 included in the liquid crystal panel 11 based on the LED data (second light emission brightness) 33. The liquid crystal data calculation unit 154 obtains liquid crystal data 32 representing the light transmittance of all the display elements 21 included in the liquid crystal panel 11 based on the input image 31 and the display brightness 36.

<1.3 Processing procedure of area active drive processing unit>
FIG. 8 is a flowchart showing the processing of the area active drive processing unit 15. An image of a certain color component (hereinafter referred to as color component C) included in the input image 31 is input to the area active drive processing unit 15 (step S11). The input image of the color component C includes the luminance of (m × n) pixels.

  Next, the area active drive processing unit 15 performs sub-sampling processing (averaging processing) on the input image of the color component C, and the luminance of (sp × sq) (s is an integer of 2 or more) pixels. A reduced image is obtained (step S12). In step S12, the input image of the color component C is reduced by (sp / m) times in the horizontal direction and (sq / n) times in the vertical direction. Next, the area active drive processing unit 15 divides the reduced image into (p × q) areas (step S13). Each area includes the luminance of (s × s) pixels. Next, for each of (p × q) areas, the area active drive processing unit 15 obtains the maximum luminance value Ma of the pixels in the area and the average luminance Me of the pixels in the area (step S14).

  Next, the area active drive processing unit 15 obtains the luminance at the time of light emission of the LED corresponding to each area (the above-mentioned first emission luminance) based on the maximum value Ma, the average value Me, and the like obtained in Step S14 (Step 1) S15). Next, the area active drive processing unit 15 corrects the first light emission luminance to the second light emission luminance by the processing including the LEDBLUR processing described above (step S16). The entire process for correcting the first light emission luminance to the second light emission luminance (the process in step S16) including the LEDBLUR process is hereinafter referred to as “light emission luminance correction process”.

  Next, the area active drive processing unit 15 applies a luminance diffusion filter (point diffusion filter) to the (p × q) second emission luminances obtained in step S16, thereby (tp × tq). First backlight luminance data including display luminances (t is an integer of 2 or more) is obtained (step S17). In step S <b> 17, (p × q) second light emission luminances are enlarged t times in the horizontal direction and the vertical direction, respectively.

  Next, the area active drive processing unit 15 obtains second backlight luminance data including (m × n) display luminances by performing linear interpolation processing on the first backlight luminance data ( Step S18). In step S18, the first backlight luminance data is enlarged (m / tp) times in the horizontal direction and (n / tq) times in the horizontal direction. The second backlight luminance data indicates that (m × n) color components C are displayed when (p × q) color component C LEDs emit light at the second light emission luminance obtained in step S16. This represents the luminance of the backlight of the color component C incident on the element 21.

  Next, the area active drive processing unit 15 determines the luminance of (m × n) pixels included in the input image of the color component C, respectively (m × n) included in the second backlight luminance data. The light transmittance T of the display element 21 of the (m × n) color components C is obtained by dividing by the display luminance (step S19).

  Finally, the area active drive processing unit 15 for the color component C, the liquid crystal data 32 representing the (m × n) light transmittances T obtained in step S19 and the (p × q) pieces obtained in step S16. LED data 33 representing the second light emission luminance is output (step S19). At this time, the liquid crystal data 32 and the LED data 33 are converted into values in a suitable range according to the specifications of the panel drive circuit 12 and the backlight drive circuit 14.

  The area active drive processing unit 15 performs the processing shown in FIG. 8 on the R image, the G image, and the B image, and based on the input image 31 including the luminance of (m × n × 3) pixels ( Liquid crystal data 32 representing m × n × 3) transmittance and LED data 33 representing (p × q × 3) second light emission luminances are obtained.

  FIG. 9 is a diagram showing a process until liquid crystal data and LED data are obtained when m = 1920, n = 1080, p = 32, q = 16, s = 10, and t = 5. As shown in FIG. 9, a reduced image including the luminance of (320 × 160) pixels is obtained by performing sub-sampling processing on the input image of the color component C including the luminance of (1920 × 1080) pixels. Is obtained. The reduced image is divided into (32 × 16) areas (area size is (10 × 10) pixels). By obtaining the maximum value Ma and the average value Me of the pixel luminance for each area, the maximum value data including (32 × 16) maximum values and the average value data including (32 × 16) average values are obtained. can get. Furthermore, (32 × 16) light emission luminances (first light emission luminances) are obtained based on the maximum value data, the average value data, and the like. The emission luminance (first emission luminance) is corrected by the LEDBLUR process, and (32 × 16) pieces of LED data of the color component C representing the corrected emission luminance (second emission luminance) are obtained.

  By applying a luminance diffusion filter to the LED data of the color component C, first backlight luminance data including (160 × 80) luminances is obtained, and linear interpolation processing is performed on the first backlight luminance data. By performing the above, second backlight luminance data including (1920 × 1080) luminances is obtained. Finally, by dividing the luminance of the pixels included in the input image by the luminance included in the second backlight luminance data, the liquid crystal data of the color component C including (1920 × 1080) light transmittances is obtained.

  In FIG. 8, for ease of explanation, the area active drive processing unit 15 sequentially performs the process for each color component image, but the process for each color component image may be performed in a time-sharing manner. . In FIG. 8, the area active drive processing unit 15 performs sub-sampling processing on the input image to remove noise, and performs area active drive based on the reduced image, but based on the original input image. Area active drive may be performed.

<1.4 Effect>
According to the present embodiment, in the liquid crystal display device that performs area active driving, after the luminance at the time of light emission of the LED corresponding to each area (first light emission luminance) is obtained based on the input image 31, the first light emission is performed. The light emission luminance is corrected by performing the LEDBLUR process based on the LED filter 155. In the LEDBLUR process, when the LED in a certain area is lit, the first luminance of the surrounding area is increased so that the luminance displayed in the area is increased by increasing the light emission luminance of the LED in the surrounding area. Is corrected. For this reason, when the single area lighting is performed, the LEDs in the area around the lighting target area are also lit with the luminance based on the correction data stored in the LED filter 155. Here, light emitted from an LED in a certain area irradiates not only the area but also the surrounding area. Therefore, the lighting target area is irradiated not only with the light emitted from the LEDs in the lighting target area, but also with the light emitted from the LEDs in the surrounding area. Thereby, the display brightness of the lighting target area is increased as compared with the conventional case, and the lack of peak brightness is solved.

  FIG. 10 is a diagram for explaining an effect in the present embodiment. FIG. 10 schematically shows the vicinity of the lighting target area before and after the LEDBLUR process. Prior to the LEDBLUR process, as shown in FIG. 10A, only the LEDs in the lighting target area are lit at the first emission luminance (obtained based on the input image 31). Since the light emitted from the LED in the lighting target area also illuminates the surrounding area, a luminance distribution as shown in FIG. After the LEDBLUR process, as shown in FIG. 10B, the LEDs in the lighting target area are lit at the first light emission luminance, and the LEDs in the surrounding areas are set to the first light emission luminance in the lighting target area. Lights up with the brightness determined based on the correction data in the LED filter 155. Since the light emitted from the LEDs in the surrounding area is also irradiated to the lighting target area, a luminance distribution as shown in FIG. 10B appears. Thus, the display brightness (peak brightness) of the lighting target area is increased by the LEDBLUR process.

  In addition, by increasing the display brightness when the single area is lit, the difference between the display brightness when the single area is lit and the display brightness when all the areas are lit is smaller than before. In the apparatus, a desired gradation display can be obtained.

<1.5 Modification>
In the above embodiment, the first light emission luminance is corrected using the LED filter, but the present invention is not limited to this. For example, a predetermined coefficient may be prepared and the coefficient may be added to the first light emission luminance, or the first light emission luminance may be multiplied by the coefficient.

<2. Second Embodiment>
<2.1 Overall configuration and processing procedure>
FIG. 11 is a block diagram showing the configuration of the liquid crystal display device 10 according to the second embodiment of the present invention. In the present embodiment, a mode switching unit 41 is provided in addition to the components in the first embodiment. The mode switching unit 41 outputs a mode signal 51 based on an external operation (for example, a manual operation by a person). The mode signal 51 is given to the area active drive processing unit 15. In the area active drive processing unit 15, liquid crystal data 32 and LED data 33 are generated based on the mode signal 51 and the input image 31. Since other configurations are the same as those of the first embodiment, description thereof is omitted. In the present embodiment, it is assumed that two modes of “luminance priority mode” (first mode) and “contrast priority mode” (second mode) are provided as selectable modes.

  FIG. 12 is a block diagram showing a detailed configuration of the area active drive processing unit 15 in the present embodiment. As shown in FIG. 12, in this embodiment, two LED filters, a first LED filter 155a and a second LED filter 155b, are provided. The mode signal 51 output from the mode switching unit 41 is given to the light emission luminance correction unit 152. When performing the above-described LED BLUR processing, the light emission luminance correction unit 152 selects either the first LED filter 155a or the second LED filter 155b according to the mode signal 51, and selects the selected LED filter for each area. Applies to

  In the present embodiment, the first LED filter 155a is as shown in FIG. 13, and the second LED filter 155b is as shown in FIG. Here, with respect to each LED filter, when the correction data values are viewed one by one from the central area to the outer area, the rate of change of the correction data values (hereinafter referred to as “data value change rate”). )). In the first LED filter 155a, the value of the correction data from the central area to the area denoted by reference numeral 71 in FIG. 13 is “100, 80, 60”. Therefore, the data value change rate is “20”. In the second LED filter 155b, the correction data values from the central area to the area indicated by reference numeral 72 in FIG. 14 are “100, 70, 20”. Therefore, the data value change rate is “40”. Thus, in this embodiment, the data value change rate of the second LED filter 155b is larger than the data value change rate of the first LED filter 155a.

  FIG. 15 is a flowchart showing a detailed processing procedure of the light emission luminance correction processing (step S16 in FIG. 8) in the present embodiment. When the light emission luminance correction process is started, the light emission luminance correction unit 152 in the area active drive processing unit 15 receives the mode signal 51 output from the mode switching unit 41 (step S31). Next, the light emission luminance correction unit 152 selects either the first LED filter 155a or the second LED filter 155b according to the mode signal 51 (step S32). Specifically, if the mode signal 51 indicates the luminance priority mode, the first LED filter 155a is selected, and if the mode signal 51 indicates the contrast priority mode, the second LED filter 155b is selected. Next, the light emission luminance correction unit 152 performs LEDBLUR processing by applying the LED filter selected in step S32 to each area (step S33). Next, the light emission luminance correction unit 152 determines LED data (second light emission luminance for each area) 33 based on the result of the LEDBLUR process (step S34). After step S34 ends, the process proceeds to step S17 in FIG.

  The above-described mode determines whether “display with priority on luminance” or “display with priority on contrast” is performed for display of the entire screen. Accordingly, in step S32, the same LED filter (either the first LED filter 155a or the second LED filter 155b) is selected for all areas.

<2.2 Effect>
According to this embodiment, during the LEDBLUR process, one of the two LED filters (the first LED filter 155a and the second LED filter 155b) is placed in each area according to the mode selected from the outside. Applied. Specifically, when the luminance priority mode is selected, the first LED filter 155a as shown in FIG. 13 is applied to each area, and when the contrast priority mode is selected, the second LED filter 155a as shown in FIG. LED filter 155b is applied to each area. Accordingly, the state in the vicinity of the lighting target area when the single area lighting is performed becomes as shown in FIG. 16A when the luminance priority mode is selected, and the contrast priority mode is selected. As shown in FIG. In the luminance priority mode, the LEDs in the surrounding area of the lighting target area are lit with a relatively high luminance, so that the luminance is distributed over a wide range and the display luminance is enhanced as a whole. This eliminates the lack of peak luminance when a single area is lit. On the other hand, in the contrast priority mode, the LEDs in the area around the lighting target area are lit with a relatively low luminance, so that the luminance is distributed only in a relatively narrow range. Therefore, high contrast can be obtained while suppressing an increase in power consumption.

<3. Third Embodiment>
<3.1 Overall configuration and processing procedure>
FIG. 17 is a block diagram showing the configuration of the liquid crystal display device 10 according to the third embodiment of the present invention. In the present embodiment, a moving image / still image determination unit 42 is provided instead of the mode switching unit 41 in the second embodiment. The moving image / still image determination unit 42 determines whether each area is a moving image or a still image based on the input image 31. Data indicating the determination result is given to the area active drive processing unit 15 as determination result data 52. In the area active drive processing unit 15, liquid crystal data 32 and LED data 33 are generated based on the determination result data 52 and the input image 31. Since other configurations are the same as those of the second embodiment, description thereof is omitted.

  The detailed configuration of the area active drive processing unit 15 is the same as that of the second embodiment (see FIG. 12). However, in the present embodiment, the determination result data 52 is given to the light emission luminance correction unit 152 instead of the mode signal 51. Also, a moving image LED filter 155m as shown in FIG. 18 is provided as the first LED filter, and a still image LED filter 155s as shown in FIG. 19 is provided as the second LED filter. Note that the data value change rate of the moving image LED filter 155m (data value change rate from the central area to the area indicated by reference numeral 73 in FIG. 18) is “25”, and the data value of the still image LED filter 155s. The rate of change (data value rate of change from the center area in FIG. 19 to the area indicated by reference numeral 74) is “40”.

  FIG. 20 is a flowchart showing a detailed processing procedure of the light emission luminance correction processing (step S16 in FIG. 8) in the present embodiment. When the light emission luminance correction process is started, the moving image / still image determination unit 42 determines whether each area is a moving image or a still image based on the input image 31 (step S41). This determination is based on the average value Me calculated in step S14 in FIG. 8, and the difference between the average value Me (n) in the current frame and the average value Me (n−1) in the previous frame is greater than a predetermined threshold Th. It is done depending on whether it is big or not. Then, determination result data 52 indicating the determination result is given to the light emission luminance correction unit 152 in the area active drive processing unit 15.

  As a result of the determination in step S41, if the difference between Me (n) and Me (n-1) is larger than the threshold Th, the light emission luminance correction unit 152 selects the moving image LED filter 155m (step S42). On the other hand, if the difference between Me (n) and Me (n−1) is equal to or smaller than the threshold Th, the light emission luminance correction unit 152 selects the still image LED filter 155s (step S43).

  Next, the light emission luminance correction unit 152 performs LEDBLUR processing by applying the LED filter selected for each area to each area (step S44). Next, the light emission luminance correction unit 152 determines the LED data 33 based on the result of the LEDBLUR process (step S45). After step S45 ends, the process proceeds to step S17 in FIG.

<3.2 Effects>
According to the present embodiment, during LEDBLUR processing, it is determined whether each area is a moving image or a still image, and a moving image LED filter 155m as shown in FIG. 18 is applied to the moving image area. A still image LED filter 155s as shown in FIG. 19 is applied to the still image area. Accordingly, the state in the vicinity of the lighting target area when the single area lighting is performed is as shown in FIG. 21A if the moving image is displayed in the lighting target area. If a still image is displayed in the target area, the display is as shown in FIG. When displaying a moving image, as shown in FIG. 21A, the LEDs in the area around the lighting target area are lit with relatively high luminance. For this reason, the luminance difference between areas becomes smaller than in the past. Thereby, even if the luminance of the LED in each area changes for each frame due to the moving image display, the occurrence of flicker is suppressed. On the other hand, when displaying a still image, as shown in FIG. 21B, the LEDs in the area around the lighting target area are lit with a relatively low luminance, so that a high contrast is achieved while suppressing an increase in power consumption. can get.

<3.3 Modification>
Next, a modification of the third embodiment will be described.

<3.3.1 First Modification>
In the third embodiment, two LED filters, ie, a moving image LED filter 155m and a still image LED filter 155s, are provided. In this modification, in addition to the moving image LED filter 155m and the still image LED filter 155s, an LED filter having an intermediate characteristic between the moving image LED filter 155m and the still image LED filter 155s (hereinafter referred to as "intermediate filter"). .) Is provided. In the following description, it is assumed that three intermediate filters are provided.

  FIG. 22 is a flowchart showing a detailed processing procedure of the light emission luminance correction processing (step S16 in FIG. 8) in the present modification. When the light emission luminance correction process is started, it is determined whether each area is a moving image or a still image in the same manner as in the third embodiment (step S51). If the result of determination in step S51 is that the difference between Me (n) and Me (n−1) is greater than the threshold value Th, the light emission luminance correction unit 152 adds “1” to a variable Cnt provided in advance. Processing is performed (step S52). However, the upper limit value of the variable Cnt is “5”. As a result of the determination in step S51, if the difference between Me (n) and Me (n-1) is equal to or smaller than the threshold Th, the light emission luminance correction unit 152 performs a process of subtracting “1” from the variable Cnt (step S51). S53). However, the lower limit value of the variable Cnt is “1”.

  Next, the light emission luminance correction unit 152 selects an LED filter according to the value of the variable Cnt for each area (step S54). In the present modification, the value “1” of the variable Cnt is associated with the still image LED filter 155s, and the value “5” of the variable Cnt is associated with the moving image LED filter 155m. Further, the values “2” to “4” of the variable Cnt are associated with the intermediate filter. Specifically, the value “2” of the variable Cnt is associated with an intermediate filter having characteristics relatively close to the characteristics of the still image LED filter 155s, and the value “4” of the variable Cnt is a characteristic of the moving image LED filter 155m. Is associated with an intermediate filter having characteristics relatively close to.

  Next, the light emission luminance correction unit 152 performs LEDBLUR processing by applying the LED filter selected for each area to each area (step S55). Next, the light emission luminance correction unit 152 determines the LED data 33 based on the result of the LEDBLUR process (step S56). After step S56 ends, the process proceeds to step S17 in FIG.

  According to this modification, in addition to the moving image LED filter 155m and the still image LED filter 155s, an intermediate filter having intermediate characteristics between the moving image LED filter 155m and the still image LED filter 155s is provided. Then, the value of the variable Cnt is added or subtracted according to the determination of whether the image is a moving image or a still image, and an LED filter to be used for LEDBLUR processing is selected based on the value of the variable Cnt. For this reason, when changing from a moving image to a still image, or when changing from a still image to a moving image, the characteristics of the LED filter used for the LEDBLUR process gradually change without abrupt change. For example, when the moving image changes to a still image, the value of the variable Cnt changes from “5” to “1” by “1” per frame. As a result, the state in the vicinity of the lighting target area when the single area lighting is performed gradually changes as shown in FIG. In this way, it is possible to change from moving image display to still image display or change from still image display to moving image display without giving a strange feeling to human eyes.

<3.3.2 Second Modification>
In the third embodiment, “luminance that can be displayed in an area when the moving image LED filter 155m is applied to a certain area” and “the still image LED filter 155s is applied to a certain area. Thus, the relationship with “luminance that can be displayed in the area” is not particularly limited. On the other hand, in this modification, “the luminance that can be displayed in a certain area by applying the moving image LED filter 155m” and “the still image LED filter 155s are applied in a certain area”. The correction data is stored in the moving image LED filter 155m and the still image LED filter 155s so that the “luminance that can be displayed in the area” is equal. Specifically, even if any of the plurality of LED filters provided in advance is applied to a certain area, the luminance that can be displayed in the area is constant by applying the LED filter. The correction data is stored in the plurality of LED filters.

  According to the present modification, as shown in FIG. 24, the luminance distribution differs between when displaying a moving image and when displaying a still image. However, the display luminance of the lighting target area when a single area is turned on It is the same for display and still image display. For this reason, it is possible to change from moving image display to still image display or change from still image display to moving image display without giving a sense of incongruity to human eyes.

<4. Fourth Embodiment>
<4.1 Overall configuration and processing procedure>
FIG. 25 is a block diagram showing the configuration of the liquid crystal display device 10 according to the fourth embodiment of the present invention. In the present embodiment, an MPL calculation unit 43 is provided instead of the mode switching unit 41 in the second embodiment. The MPL calculation unit 43 determines whether each area is a moving image or a still image based on the input image 31, and the ratio of the number of moving image areas to the total number of areas (hereinafter referred to as “MPL” or “screen moving image rate”). MPL data 53 representing the above is obtained. The MPL data 53 is given to the area active drive processing unit 15. In the area active drive processing unit 15, liquid crystal data 32 and LED data 33 are generated based on the MPL data 53 and the input image 31. Since other configurations are the same as those of the second embodiment, description thereof is omitted.

  The detailed configuration of the area active drive processing unit 15 is the same as that of the second embodiment (see FIG. 12). However, in this embodiment, the MPL data 53 is given to the light emission luminance correction unit 152 instead of the mode signal 51. Similarly to the third embodiment, a moving image LED filter 155m is provided as the first LED filter, and a still image LED filter 155s is provided as the second LED filter.

  FIG. 26 is a flowchart showing a detailed processing procedure of the light emission luminance correction processing (step S16 in FIG. 8) in the present embodiment. When the light emission luminance correction process is started, the MPL calculation unit 43 determines whether each area is a moving image or a still image based on the input image 31 (step S61). Next, the MPL calculation unit 43 calculates an MPL (screen moving image rate) by dividing the number of areas determined to be a moving image area by the total number of areas (step S62). The MPL data 53 indicating the MPL calculated in step S62 is given to the light emission luminance correction unit 152 in the area active drive processing unit 15.

  Next, the light emission luminance correction unit 152 determines whether or not MPL is larger than a predetermined threshold Th (step S63). If the result of determination in step S63 is that MPL is greater than a predetermined threshold Th, the light emission luminance correction unit 152 selects the moving image LED filter 155m (step S64). On the other hand, if the MPL is equal to or smaller than the predetermined threshold Th, the light emission luminance correction unit 152 selects the still image LED filter 155s (step S65).

  Next, the light emission luminance correction unit 152 performs LEDBLUR processing by applying the LED filter selected according to the MPL to each area (step S66). In this embodiment, since the LED filter is selected based on the ratio of the number of moving image areas to the total number of areas, the same LED filter is applied to all areas. Next, the light emission brightness correction unit 152 determines the LED data 33 based on the result of the LEDBLUR process (step S67). After step S67 is completed, the process proceeds to step S17 in FIG.

<4.2 Effects>
According to the present embodiment, in the LEDBLUR process, the moving image LED filter 155m is selected if the MPL (ratio of the moving image area number to the total area number) is relatively high, and if the MPL is relatively low, the still image LED filter is selected. 155s is selected. For this reason, the state in the vicinity of the lighting target area when the single area lighting is performed is as shown in FIG. 21A when the ratio of the moving image to the entire image is relatively high, and occupies the entire image. When the ratio of still images is relatively high, the result is as shown in FIG. As a result, as in the third embodiment, the occurrence of flicker during moving image display is suppressed. As in the third embodiment, when displaying a still image, high contrast is obtained while suppressing an increase in power consumption.

<5. Fifth Embodiment>
<5.1 Overall configuration and processing procedure>
FIG. 27 is a block diagram showing a configuration of a liquid crystal display device 10 according to the fifth embodiment of the present invention. In the present embodiment, a temperature sensor 44 is provided instead of the mode switching unit 41 in the second embodiment. The temperature sensor 44 detects the temperature of the backlight 13 provided in the liquid crystal display device 10 and outputs detected temperature data 54 indicating the detected temperature. The detected temperature data 54 is given to the area active drive processing unit 15. In the area active drive processing unit 15, liquid crystal data 32 and LED data 33 are generated based on the detected temperature data 54 and the input image 31. Since other configurations are the same as those of the second embodiment, description thereof is omitted.

  The detailed configuration of the area active drive processing unit 15 is the same as that of the second embodiment (see FIG. 12). However, in the present embodiment, the detected temperature data 54 is given to the light emission luminance correction unit 152 instead of the mode signal 51. In the present embodiment, a normal LED filter is provided as the first LED filter, and a heat generation suppressing LED filter is provided as the second LED filter. Note that the value of the correction data for the heat generation suppression LED filter is generally set to a lower value than the value of the correction data for the normal LED filter.

  FIG. 28 is a flowchart showing a detailed processing procedure of the light emission luminance correction processing (step S16 in FIG. 8) in the present embodiment. When the light emission luminance correction process is started, the light emission luminance correction unit 152 in the area active drive processing unit 15 acquires the detected temperature data 54 output from the temperature sensor 44 (step S71). Next, the light emission luminance correction unit 152 determines whether or not the detected temperature Temp indicated by the detected temperature data 54 is larger than a predetermined threshold Th (step S72). If the result of determination in step S72 is that the detected temperature Temp is greater than a predetermined threshold Th, the light emission luminance correction unit 152 selects a heat generation suppression LED filter (step S73). On the other hand, if the detected temperature Temp is equal to or lower than the predetermined threshold Th, the light emission luminance correction unit 152 selects the normal LED filter (step S74).

  Next, the light emission luminance correction unit 152 performs LED BLUR processing by applying the LED filter selected according to the detected temperature Temp to each area (step S75). Next, the light emission brightness correction unit 152 determines the LED data 33 based on the result of the LEDBLUR process (step S76). After step S76 ends, the process proceeds to step S17 in FIG.

  When the detected temperature data 54 can be acquired for each area, either a normal LED filter or a heat generation suppression LED filter is selected for each area, and LEDBLUR processing is performed based on the selected LED filter. It can be performed. On the other hand, when the detected temperature data 54 cannot be acquired for each area, the same LED filter is applied to all areas.

<5.2 Effects>
According to the present embodiment, the normal LED filter and the heat generation suppression LED filter are provided in advance. If the temperature of the backlight 13 becomes higher than a predetermined value, the LED BLUR process is performed based on the heat generation suppression LED filter. Done. Here, the value of the correction data of the heat generation suppressing LED filter is set to a low value as a whole. For this reason, thermal runaway due to an increase in the temperature of the backlight is suppressed, and power consumption is reduced.

<6. Sixth Embodiment>
<6.1 Overall configuration and processing procedure>
FIG. 29 is a block diagram showing the configuration of the liquid crystal display device 10 according to the sixth embodiment of the present invention. In the present embodiment, an illuminance sensor 45 is provided in place of the mode switching unit 41 in the second embodiment. The illuminance sensor 45 detects the brightness (illuminance) around the liquid crystal display device 10 and outputs detected illuminance data 55 indicating the detected illuminance. The detected illuminance data 55 is given to the area active drive processing unit 15. In the area active drive processing unit 15, liquid crystal data 32 and LED data 33 are generated based on the detected illuminance data 55 and the input image 31. Since other configurations are the same as those of the second embodiment, description thereof is omitted.

  The detailed configuration of the area active drive processing unit 15 is the same as that of the second embodiment (see FIG. 12). However, in this embodiment, the detected illuminance data 55 is given to the light emission luminance correction unit 152 instead of the mode signal 51. Similarly to the third embodiment, a moving image LED filter 155m is provided as the first LED filter, and a still image LED filter 155s is provided as the second LED filter.

  FIG. 30 is a flowchart showing a detailed processing procedure of the light emission luminance correction processing (step S16 in FIG. 8) in the present embodiment. When the light emission luminance correction process is started, the light emission luminance correction unit 152 in the area active drive processing unit 15 acquires the detected illuminance data 55 output from the illuminance sensor 45 (step S81). Next, the light emission luminance correction unit 152 determines whether or not the detected illuminance Lum indicated by the detected illuminance data 55 is greater than a predetermined threshold Th (step S82). If the result of determination in step S82 is that the detected illuminance Lum is greater than the predetermined threshold Th, the light emission luminance correction unit 152 selects the still image LED filter 155s (step S83). On the other hand, if the detected illuminance Lum is equal to or smaller than the predetermined threshold Th, the light emission luminance correction unit 152 selects the moving image LED filter 155m (step S84).

  Next, the light emission luminance correction unit 152 performs the LEDBLUR process by applying the LED filter selected according to the detected illuminance Lum to each area (step S85). Next, the light emission brightness correction unit 152 determines the LED data 33 based on the result of the LEDBLUR process (step S86). After step S86 ends, the process proceeds to step S17 in FIG.

<6.2 Effects>
According to this embodiment, in the LEDBLUR process, the moving image LED filter 155m is selected if the detected illuminance Lum is relatively low, and the still image LED filter 155s is selected if the detected illuminance Lum is relatively high. Therefore, the state in the vicinity of the lighting target area when the single area lighting is performed is as shown in FIG. 21A when the liquid crystal display device is used in a relatively dark environment. When this liquid crystal display device is used in a relatively bright environment, the result is as shown in FIG. Flicker during video display becomes more prominent when the screen is darker than when the screen is bright. When the liquid crystal display device is used in a relatively dark environment, the LEDBLUR process is used to display flicker as shown in FIG. As described above, the luminance distribution range is widened, and the display luminance is improved as a whole. This suppresses the occurrence of flicker when displaying a moving image.

<7. Seventh Embodiment>
<7.1 Overall Configuration and Processing Procedure>
FIG. 31 is a block diagram showing the configuration of the liquid crystal display device 10 according to the sixth embodiment of the present invention. In the present embodiment, an APL calculation unit 46 is provided instead of the mode switching unit 41 in the second embodiment. The APL calculation unit 16 obtains APL data 56 representing the average luminance level (hereinafter referred to as “APL” or “screen average luminance”) of an image for one frame based on the input image 31. The APL data 56 is given to the area active drive processing unit 15. In the area active drive processing unit 15, liquid crystal data 32 and LED data 33 are generated based on the APL data 56 and the input image 31. Since other configurations are the same as those of the second embodiment, description thereof is omitted.

  The detailed configuration of the area active drive processing unit 15 is the same as that of the second embodiment (see FIG. 12). However, in the present embodiment, APL data 56 is given to the light emission luminance correction unit 152 instead of the mode signal 51. Similarly to the third embodiment, a moving image LED filter 155m is provided as the first LED filter, and a still image LED filter 155s is provided as the second LED filter.

  FIG. 32 is a flowchart showing a detailed processing procedure of the light emission luminance correction processing (step S16 in FIG. 8) in the present embodiment. When the light emission luminance correction process is started, the APL calculation unit 46 calculates APL (screen average luminance) based on the input image 31 (step S91). The APL data 56 indicating the APL calculated in step S91 is given to the light emission luminance correction unit 152 in the area active drive processing unit 15.

  Next, the light emission luminance correction unit 152 determines whether or not APL is larger than a predetermined threshold Th (step S92). If the result of determination in step S92 is that APL is greater than a predetermined threshold Th, the light emission luminance correction unit 152 selects the still image LED filter 155s (step S93). On the other hand, if APL is equal to or smaller than the predetermined threshold Th, the light emission luminance correction unit 152 selects the moving image LED filter 155m (step S94).

  Next, the light emission luminance correction unit 152 performs LEDBLUR processing by applying the LED filter selected according to APL to each area (step S95). In this embodiment, since the LED filter is selected based on the average luminance of the entire screen, the same LED filter is applied to all areas. Next, the light emission luminance correction unit 152 determines the LED data 33 based on the result of the LEDBLUR process (step S96). After step S96 ends, the process proceeds to step S17 in FIG.

<7.2 Effects>
According to the present embodiment, in the LEDBLUR process, the moving image LED filter 155m is selected if the APL (average screen brightness) is relatively low, and the still image LED filter 155s is selected if the APL is relatively high. Therefore, the state in the vicinity of the lighting target area when the single area lighting is performed is as shown in FIG. 21A when the screen is entirely dark, and when the screen is bright as a whole, 21 (b). Flicker during video display becomes more prominent when the screen is darker than when the screen is bright. When the screen is entirely dark, the LEDBLUR process widens the luminance distribution range as shown in FIG. As a result, the overall display brightness is increased. This suppresses the occurrence of flicker when displaying a moving image.

<8. Other>
In each said embodiment, although the backlight 13 is comprised by red LED23, green LED24, and blue LED25, you may comprise a backlight by white LED. When the backlight is composed of white LEDs, the area active drive processing unit 15 generates a Y image (luminance image) based on, for example, the R image, the G image, and the B image, and includes steps in the processing shown in FIG. S11 to S18 may be performed on the Y image, and step S19 may be performed on the combination of each of the three color images and the Y image. Moreover, the backlight can also be comprised with a cold cathode tube (CCFL: Cold Cathode Fluorescent Lamp) by making the shape of a LED filter into 5 rows (column) x 1 column (row), for example.

  In each of the above embodiments, the LED unit 22 includes one red LED 23, one green LED 24, and one blue LED 25. However, the number of three color LEDs included in the LED unit 22 may be other than this. For example, the LED unit 22 may include one red LED 23 and one blue LED 25 and two green LEDs 24. In this case, the backlight drive circuit 14 may control the two green LEDs 24 so that the sum of the luminances of the two green LEDs 24 becomes the luminance determined in step S16 (second emission luminance).

  Further, the frame rate in the liquid crystal display device may be arbitrary, and may be, for example, 30 Hz, 60 Hz, 120 Hz, or higher. The higher the frame rate, the less the flicker becomes noticeable because the brightness of the LED changes in smaller units. In addition, the same effect as in the case of the liquid crystal display device can be obtained by performing LEDBLUR processing while selecting a suitable LED filter from a plurality of LED filters as described above in an arbitrary image display device having a backlight. be able to.

FIG. 3 is a block diagram illustrating a detailed configuration of an area active drive processing unit in the liquid crystal display device according to the first embodiment of the present invention. It is a block diagram which shows the structure of the liquid crystal display device which concerns on the said 1st Embodiment. It is a figure which shows the detail of the backlight shown in FIG. It is a figure which shows the example of the LED filter in the said 1st Embodiment. In the said 1st Embodiment, it is a figure for demonstrating a LEDBLUR process. In the said 1st Embodiment, it is a figure for demonstrating a LEDBLUR process. In the said 1st Embodiment, it is a figure for demonstrating a LEDBLUR process. 4 is a flowchart showing processing of an area active drive processing unit in the liquid crystal display device according to the first embodiment. It is a figure which shows progress until liquid crystal data and LED data are obtained in the said 1st Embodiment. It is a figure for demonstrating the effect in the said 1st Embodiment. It is a block diagram which shows the structure of the liquid crystal display device which concerns on the 2nd Embodiment of this invention. It is a block diagram which shows the detailed structure of the area active drive process part in the said 2nd Embodiment. In the said 2nd Embodiment, it is a figure which shows a 1st LED filter. In the said 2nd Embodiment, it is a figure which shows a 2nd LED filter. It is a flowchart which shows the detailed process sequence of the light emission brightness correction process in the said 2nd Embodiment. It is a figure for demonstrating the effect in the said 2nd Embodiment. It is a block diagram which shows the structure of the liquid crystal display device which concerns on the 3rd Embodiment of this invention. In the said 3rd Embodiment, it is a figure which shows the LED filter for moving images. In the said 3rd Embodiment, it is a figure which shows the LED filter for still images. In the said 3rd Embodiment, it is a flowchart which shows the detailed process sequence of the light emission brightness correction process. It is a figure for demonstrating the effect in the said 3rd Embodiment. It is a flowchart which shows the detailed process sequence of the light emission luminance correction process in the 1st modification of the said 3rd Embodiment. It is a figure for demonstrating the effect in the 1st modification of the said 3rd Embodiment. It is a figure for demonstrating the effect in the 2nd modification of the said 3rd Embodiment. It is a block diagram which shows the structure of the liquid crystal display device which concerns on the 4th Embodiment of this invention. It is a flowchart which shows the detailed process sequence of the light emission brightness correction process in the said 4th Embodiment. It is a block diagram which shows the structure of the liquid crystal display device which concerns on the 5th Embodiment of this invention. It is a flowchart which shows the detailed process sequence of the light emission brightness correction process in the said 5th Embodiment. It is a block diagram which shows the structure of the liquid crystal display device which concerns on the 6th Embodiment of this invention. In the said 6th Embodiment, it is a flowchart which shows the detailed process sequence of the light emission brightness correction process. It is a block diagram which shows the structure of the liquid crystal display device which concerns on the 7th Embodiment of this invention. In the said 7th Embodiment, it is a flowchart which shows the detailed process sequence of the light emission brightness correction process. In a prior art example, it is a figure for demonstrating the point from which the brightness | luminance which appears in an area differs at the time of single area lighting and all area lighting. It is a figure which shows the example of the screen which a flicker generate | occur | produces in a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Liquid crystal display device 11 ... Liquid crystal panel 12 ... Panel drive circuit 13 ... Backlight 14 ... Backlight drive circuit 15 ... Area active drive process part 21 ... Display element 31 ... Input image 32 ... Liquid crystal data 33 ... LED data (2nd Brightness)
34 ... First light emission luminance 35 ... Correction data 36 ... Display luminance 41 ... Mode switching unit 51 ... Mode signal 151 ... Light emission luminance calculation unit 152 ... Light emission luminance correction unit 153 ... Display luminance calculation unit 154 ... Liquid crystal data calculation unit 155 ... LED filter

Claims (22)

An image display device having a function of controlling the brightness of a backlight,
A display panel including a plurality of display elements;
A backlight including a plurality of light sources;
A light emission luminance calculation unit that divides the input image into a plurality of areas and obtains the luminance at the time of light emission of the light source corresponding to each area as the first light emission luminance based on the input image corresponding to each area;
A light emission luminance correction unit for obtaining a second light emission luminance by correcting the first light emission luminance based on predetermined correction data, and outputting data indicating the second light emission luminance as light emission luminance control data;
A display data calculation unit for obtaining display data for controlling the light transmittance of the display element based on the input image and the light emission luminance control data;
A panel drive circuit that outputs a signal for controlling the light transmittance of the display element to the display panel based on the display data;
A backlight driving circuit that outputs a signal for controlling the luminance of the light source to the backlight based on the emission luminance control data;
A correction filter that stores the correction data for one area and a plurality of predetermined areas around the area;
When the correction filter defines an arbitrary area as a target area, the correction filter determines the brightness at which the light source emits light in a plurality of predetermined areas around the target area according to the first light emission luminance of the target area. Is stored as the correction data,
The light emission luminance correction unit is
By applying the correction filter to each area, the first emission luminance for a plurality of predetermined areas centered on each area is obtained based on the correction data stored in the applied correction filter. Correct ,
An image display device characterized in that a sum of luminance for each area obtained as a result of applying the correction filter to the plurality of areas is set as a second emission luminance of each area . The light emission luminance correction unit is configured such that the second light emission luminance is higher than the first light emission luminance for a plurality of predetermined areas except for the area centered on the area where the first light emission luminance is not zero. The image display device according to claim 1, wherein the first light emission luminance for the predetermined plurality of areas is corrected. A plurality of different correction filters are provided,
The image display device according to claim 1 , wherein the light emission luminance correction unit applies one of the plurality of correction filters for each area. It further includes a mode selection unit that accepts an external mode selection,
The emission luminance correcting unit, based on the mode that has been accepted by the mode selection unit, and selects the correction filter to be applied in correcting the first emission luminance, according to claim 3 Image display device. A first correction filter and a second correction filter as the plurality of correction filters;
The first mode and the second mode are provided as modes that can be selected from the outside,
Regarding the data value of the correction data for each area stored in the correction filter, the rate of change of the data value when the area of interest moves from the center to the outside is defined as the data value change rate. Correction for the first correction filter and the second correction filter so that the data value change rate for the second correction filter is larger than the data value change rate for the first correction filter. Data is stored,
If the mode received by the mode selection unit is the first mode, the light emission luminance correction unit selects the first correction filter when correcting the first light emission luminance, and the mode 5. The second correction filter according to claim 4 , wherein when the mode received by the selection unit is the second mode, the second correction filter is selected when correcting the first light emission luminance. Image display device. Based on the input image, further comprises an image determination unit for determining whether each area is a moving image or a still image,
The emission luminance correcting unit, for each area, based on a determination result of the image determining unit, and selects the correction filter to be applied in correcting the first emission luminance, claim 3 The image display device described in 1. A first correction filter and a second correction filter as the plurality of correction filters;
Regarding the data value of the correction data for each area stored in the correction filter, the rate of change of the data value when the area of interest moves from the center to the outside is defined as the data value change rate. Correction for the first correction filter and the second correction filter so that the data value change rate for the second correction filter is larger than the data value change rate for the first correction filter. Data is stored,
The light emission luminance correction unit selects the first correction filter when correcting the first light emission luminance for the area determined to be a moving image by the image determination unit, and the image determination unit The image display apparatus according to claim 6 , wherein the second correction filter is selected when correcting the first light emission luminance for an area determined to be a still image. One or more correction filters such that the rate of change of the data value is larger than the first correction filter and smaller than the second correction filter;
A variable value changing unit that changes a value of a predetermined variable according to a determination result by the image determining unit;
The image display according to claim 7 , wherein the light emission luminance correction unit selects a correction filter to be applied when correcting the first light emission luminance based on a value of the predetermined variable. apparatus. When the luminance that can be displayed in an area to which the correction filter is applied is defined as display luminance, any of the plurality of correction filters is applied to each area. the display luminance is characterized in that the correction data to the plurality of correction filter to be constant is also stored, the image display apparatus according to any one of claims 6 to 8. A moving image rate that determines whether each area is a moving image or a still image based on the input image, and calculates a ratio of the number of areas determined to be moving images to the number of the plurality of areas as a screen moving image rate A calculation unit;
The image display apparatus according to claim 3 , wherein the light emission luminance correction unit selects a correction filter to be applied when correcting the first light emission luminance based on the screen moving image rate. An average luminance calculating unit for calculating an average luminance of the input image for one screen;
The emission luminance correcting unit, on the basis of the average luminance calculated by the average luminance calculator, and selects the correction filter to be applied in correcting the first emission luminance, claim 3 The image display device described in 1. An image display method in an image display device comprising a display panel including a plurality of display elements and a backlight including a plurality of light sources,
A light emission luminance calculating step of dividing the input image into a plurality of areas and obtaining the light emission luminance of the light source corresponding to each area as the first light emission luminance based on the input image corresponding to each area;
A light emission luminance correction step of obtaining a second light emission luminance by correcting the first light emission luminance based on predetermined correction data, and outputting data indicating the second light emission luminance as light emission luminance control data;
A display data calculation step for obtaining display data for controlling the light transmittance of the display element based on the input image and the light emission luminance control data;
A panel driving step for outputting a signal for controlling the light transmittance of the display element to the display panel based on the display data;
A backlight driving step for outputting a signal for controlling the luminance of the light source to the backlight based on the emission luminance control data;
The image display device includes a correction filter that stores the correction data for one area and a plurality of predetermined areas around the area.
When the correction filter defines an arbitrary area as a target area, the correction filter determines the brightness at which the light source emits light in a plurality of predetermined areas around the target area according to the first light emission luminance of the target area. Is stored as the correction data,
In the light emission luminance correction step,
By applying the correction filter for each area, the first emission luminance for a plurality of predetermined areas centered on each area is based on the correction data stored in the applied correction filter. Corrected ,
The image display method according to claim 1, wherein a sum of luminances for each area obtained as a result of applying the correction filter to the plurality of areas is set as a second light emission luminance of each area . In the light emission luminance correction step, the second light emission luminance is higher than the first light emission luminance with respect to an area where the first light emission luminance is not 0 and a predetermined plurality of areas excluding the area centered on the area. The image display method according to claim 12 , wherein the first light emission luminance for the predetermined plurality of areas is corrected. The image display device includes a plurality of different correction filters,
13. The image display method according to claim 12 , wherein in the light emission luminance correction step, one of the plurality of correction filters is applied to each area. It further comprises a mode selection step for accepting an external mode selection,
Wherein the emission luminance correcting step, based on said mode accepted in the selection step mode, characterized in that the correction filter to be applied is selected in correcting the first emission luminance, in claim 14 The image display method described. The image display device includes a first correction filter and a second correction filter as the plurality of correction filters,
The first mode and the second mode are provided as modes that can be selected from the outside,
Regarding the data value of the correction data for each area stored in the correction filter, the rate of change of the data value when the area of interest moves from the center to the outside is defined as the data value change rate. Correction for the first correction filter and the second correction filter so that the data value change rate for the second correction filter is larger than the data value change rate for the first correction filter. Data is stored,
In the light emission luminance correction step, if the mode accepted in the mode selection step is the first mode, the first correction filter is selected when correcting the first light emission luminance, and the mode 16. The second correction filter is selected when correcting the first light emission luminance if the mode accepted in the selection step is the second mode. Image display method. Further comprising an image determination step for determining whether each area is a moving image or a still image based on the input image;
In the light emission luminance correction step, a correction filter to be applied when correcting the first light emission luminance is selected for each area based on the determination result in the image determination step. Item 15. The image display method according to Item 14 . The image display device includes a first correction filter and a second correction filter as the plurality of correction filters,
Regarding the data value of the correction data for each area stored in the correction filter, the rate of change of the data value when the area of interest moves from the center to the outside is defined as the data value change rate. Correction for the first correction filter and the second correction filter so that the data value change rate for the second correction filter is larger than the data value change rate for the first correction filter. Data is stored,
In the light emission luminance correction step, the first correction filter is selected when correcting the first light emission luminance for the area determined to be a moving image in the image determination step, and in the image determination step. 18. The image display method according to claim 17 , wherein the second correction filter is selected when correcting the first light emission luminance for an area determined to be a still image. A variable value changing step of changing a value of a predetermined variable according to a determination result in the image determination step;
The image display device further includes one or more correction filters such that the data value change rate is larger than the first correction filter and smaller than the second correction filter,
19. The image according to claim 18 , wherein in the light emission luminance correction step, a correction filter to be applied when correcting the first light emission luminance is selected based on a value of the predetermined variable. Display method. When the luminance that can be displayed in an area to which the correction filter is applied is defined as display luminance, any of the plurality of correction filters is applied to each area. wherein the correction data is stored in the plurality of correction filters so that the display luminance becomes constant even if the image display method according to any one of claims 17 to 19. A moving image rate that determines whether each area is a moving image or a still image based on the input image, and calculates a ratio of the number of areas determined to be moving images to the number of the plurality of areas as a screen moving image rate A calculation step,
The image display method according to claim 14 , wherein, in the light emission luminance correction step, a correction filter to be applied when correcting the first light emission luminance is selected based on the screen moving image rate. . An average luminance calculating step for calculating an average luminance of the input image for one screen;
The correction filter to be applied when correcting the first emission luminance is selected based on the average luminance calculated in the average luminance calculation step in the emission luminance correction step. 14. The image display method according to 14 .

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