JP2013092700A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To dispense with a frame memory for synchronizing lighting control of a backlight with drive control of a liquid crystal panel, to attain simplification of a liquid crystal display device and reduction of cost and to effectively enhance brightness of a video, by speeding up the lighting control of the backlight and preventing the occurrence of delay.SOLUTION: A backlight control section 24 that is provided in the liquid crystal display device for displaying a video, determines first luminance in each area of the backlight for illuminating each area of the video on the basis of information of the luminance of each area of the video, for each area of the backlight, uniformly multiplies the first luminance of each area by a fixed magnification set according to the genre of the video to set second luminance of each area of the backlight and controls lighting of each area of the backlight using the second luminance of each area, for each area of the backlight.

Description

  The present invention relates to a liquid crystal display device that displays an image.

  Conventionally, this is called local dimming, which reduces the power of the backlight and increases the contrast of the video by setting the brightness of each region of the backlight corresponding to each region of the video according to the luminance of each region of the video Technology is used (see Patent Document 1).

  In this local dimming, if the difference in luminance between the high luminance region and the low luminance region is large in the backlight, bright lines may be generated on the screen. For this reason, there is a technique for reducing the difference in luminance between the high luminance region and the low luminance region by increasing the luminance of the low luminance region (see Patent Document 2). However, although this technique can suppress the generation of bright lines, the contrast of the video is lowered.

  Therefore, a high-brightness local dimming technique for increasing the brightness of the backlight in units of regions while suppressing a decrease in contrast has been developed. FIG. 13 is a diagram for explaining this conventional high-intensity local dimming. In this high brightness local dimming, first, the brightness of each area of the backlight corresponding to each area of the video is set according to the brightness of each area of the video. FIG. 13A shows the luminances set for the eight regions (regions 1 to 8) of the backlight.

And the brightness | luminance of each area | region of a backlight is correct | amended to a higher value on the conditions that those total values become below a predetermined value. As shown in FIG. 13B, the luminance of each region shown in FIG. 13A is such that the total value thereof is 3600 cd / m ² (= 450 cd / m ² × 8) or less. Each value is corrected to be doubled. Here, making the total luminance value of each region below a predetermined value corresponds to making the total current value for lighting each region below a predetermined value. Thereby, it is possible to prevent the power consumption from becoming very large when increasing the luminance of each area of the backlight.

JP 2007-286627 A JP 2010-244013 A

  However, in the high-intensity local dimming described above, in order to satisfy the condition that the total current value does not exceed a predetermined allowable current value, first, the current values of all regions are provisionally determined, and the total of the temporarily determined current values is calculated. It is necessary to calculate. Then, it is determined how many times the predetermined allowable current value is the total, and further, the current value to be distributed to each region is calculated by multiplying the temporarily determined current value of each region by the magnification. Is executed.

  As described above, in this high-luminance local dimming, processing for calculating the sum of the current values of the respective regions is further added. Therefore, a delay of at least one frame occurs in the backlight lighting control, and the backlight lighting control and the liquid crystal panel are controlled. In order to synchronize with the drive control, a frame memory is required. Further, since the frame memory is required, there is a problem that the apparatus configuration becomes complicated and the manufacturing cost of the apparatus increases.

  Particularly when the user plays a game, the delay in the backlight lighting control significantly reduces the operability of the user, and therefore the delay needs to be eliminated as much as possible. Therefore, there is a need for a device that secures real-time performance of the game while suppressing a decrease in the contrast of the video.

  In view of the above problems, the present invention provides a frame memory for synchronizing the backlight lighting control and the liquid crystal panel drive control by speeding up the backlight lighting control and preventing the occurrence of delay. It is an object of the present invention to provide a liquid crystal display device that can be made unnecessary, realizes simplification and cost reduction of the device, and can effectively increase the brightness of an image.

  In order to solve the above-described problem, a first technical means of the present invention is a liquid crystal display device that displays an image, wherein the first luminance of each region of a backlight that illuminates each region of the image is obtained, Based on the luminance information of each area of the video, determined for each area of the backlight, the first luminance of each area is uniformly multiplied by a constant magnification set according to the genre of the video, A backlight control unit that sets a second luminance of each area of the backlight and controls lighting of each area of the backlight for each area of the backlight using the second luminance of each area; It is characterized by that.

  According to a second technical means of the present invention, in the first technical means, when the genre of the video is a game, the backlight control unit turns on each area of the backlight. It controls by every.

  According to a third technical means of the present invention, in the first or second technical means, a predetermined allowable value for the total value of the drive current of the backlight when each region of the backlight is lit at the first luminance. The fixed magnification is smaller than the magnification of the current value.

  According to a fourth technical means of the present invention, in any one of the first to third technical means, the backlight control unit further sets a fixed magnification set based on brightness information around the device itself. The second luminance of each area of the backlight is set by uniformly multiplying the first luminance of each area of the backlight.

  According to a fifth technical means of the present invention, in any one of the first to fourth technical means, the backlight control unit is set based on information on a luminance setting value input by operating the input device. Further, the second luminance of each area of the backlight is set by further multiplying the first luminance of each area of the backlight uniformly by the constant magnification.

  According to a sixth technical means of the present invention, in any one of the first to fifth technical means, the information processing apparatus further includes a storage unit that stores APL information corresponding to the video genre in association with the video genre. The backlight control unit searches for APL information corresponding to the genre of the video, and sets the constant magnification based on the APL information obtained as a result of the search.

  According to a seventh technical means of the present invention, in the sixth technical means, the backlight control unit updates the APL information stored in the storage unit based on the APL information of the video displayed in the past. It is characterized by that.

  According to an eighth technical means of the present invention, in any one of the first to seventh technical means, the backlight control unit is configured such that when the video is a video input to a game input terminal, The fixed magnification is set to 1.

  According to a ninth technical means of the present invention, in any one of the first to seventh technical means, the backlight control unit, when the video is a video input to an input terminal for a personal computer, The fixed magnification is set to 1.

  According to a tenth technical means of the present invention, in any one of the first to ninth technical means, the backlight control unit is set based on information of a video mode in which the image quality of the video is set in advance. The second luminance of each region of the backlight is set by further multiplying the first luminance of each region of the backlight uniformly by a constant magnification.

  According to an eleventh technical means of the present invention, in the tenth technical means, the backlight control unit sets the second luminance of each region of the backlight when the video mode is a game mode. It is characterized by.

  According to a twelfth technical means of the present invention, in the tenth technical means, the backlight control unit is configured to output the second region of each area of the backlight when the video mode is an output image display mode of a personal computer. The brightness is set.

  According to a thirteenth technical means of the present invention, in the tenth technical means, the backlight control unit increases the second luminance of each area of the backlight more than the first luminance of each area of the backlight. It is characterized by making it.

  A fourteenth technical means of the present invention is a liquid crystal display device for displaying an image, wherein the first luminance of each region of the backlight that illuminates each region of the image is set to the luminance of each region of the image. It is determined for each area of the backlight based on the information, and the first luminance of each area is uniformly multiplied by a constant magnification set according to the brightness of the surroundings of the own device to And a backlight control unit configured to control the lighting of each area of the backlight for each area of the backlight using the second luminance of each area.

  A fifteenth technical means of the present invention is a liquid crystal display device for displaying an image, wherein the first luminance of each region of the backlight that illuminates each region of the image is set to the luminance of each region of the image. Each backlight region is determined based on the information, and the first luminance of each region is uniformly multiplied by a fixed magnification set according to the luminance setting value information input by operating the input device. Then, a second brightness of each area of the backlight is set, and a backlight control unit that controls lighting of each area of the backlight for each area of the backlight using the second brightness of each area It is characterized by providing.

  According to a sixteenth technical means of the present invention, there is provided a liquid crystal display device for displaying an image, wherein the first luminance of each region of the backlight that illuminates each region of the image is represented by the luminance of each region of the image. Each backlight area is determined based on the information, and the first luminance of each area is uniformly multiplied by a fixed magnification set according to the type of the input terminal to which the video is input. A backlight control unit configured to control the lighting of each area of the backlight for each area of the backlight using the second luminance of each area. Features.

  According to a seventeenth technical means of the present invention, there is provided a liquid crystal display device for displaying an image, wherein the first luminance of each region of the backlight that illuminates each region of the image is the luminance of each region of the image. It is determined for each area of the backlight based on the information, and the first luminance of each area is uniformly multiplied by a fixed magnification set in advance according to the information of the video mode in which the image quality of the video is set in advance. A backlight control unit configured to set a second brightness of each area of the backlight and control lighting of each area of the backlight for each area of the backlight using the second brightness of each area; It is characterized by providing.

  According to the present invention, the calculation processing of the sum of current values in the above-described prior art is not performed, and the first luminance of each area of the backlight that illuminates each area of the video is obtained, and the luminance information of each area of the video is displayed. Is determined for each backlight area, and the first brightness of each area is uniformly multiplied by a fixed magnification set according to the video genre to set the second brightness of each area of the backlight. In addition, since the lighting of each area of the backlight is controlled for each backlight area using the second luminance of each area, the brightness of the image can be effectively increased and the lighting of the backlight is controlled. Can be increased by at least one frame. In addition, the frame memory used for performing the current value calculation process is not necessary, and the apparatus can be simplified and the cost can be reduced.

It is a block diagram which shows an example of a structure of the liquid crystal display device which concerns on this invention. It is a figure which shows an example of a video genre and APL conversion table. It is a figure explaining the setting of APL corresponding to each video genre. It is a figure which shows the relationship between the maximum brightness | luminance which a backlight can light-emit, and APL. It is a figure which shows the relationship between the electric power supplied with respect to a backlight, and APL when a backlight light-emits by the maximum brightness | luminance. It is a figure which shows an example of a video mode and luminance conversion table. It is a figure which shows an example of a brightness and luminance conversion table. It is a figure which shows an example of a light control value and brightness | luminance conversion table. It is a figure explaining the brightness | luminance setting processing by local dimming. It is a figure explaining calculation of the correction value of luminance. It is a flowchart which shows an example of the process sequence of the backlight lighting process which concerns on this invention. It is a flowchart which shows an example of the process sequence of the backlight lighting process which concerns on this invention. It is a figure explaining the conventional high-intensity local dimming.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an example of the configuration of a liquid crystal display device 10 according to the present invention. As shown in FIG. 1, the liquid crystal display device 10 includes an antenna 11, a tuner 12, a game input terminal 13, a personal computer input terminal 14, a decoder 15, a brightness sensor 16, a remote control light receiving unit 17, a storage unit 18, A microcomputer 19, an area luminance setting unit 20, an LED (Light Emitting Diode) control unit 21, a timing controller 22, a liquid crystal panel 23, an LED driver 24, and a backlight 25 are provided. Here, the microcomputer 19, the region luminance setting unit 20, and the LED control unit 21 constitute a backlight control unit 26 that controls lighting of the backlight 25.

  The antenna 11 is an antenna that receives a television broadcast, a data broadcast of an electronic program guide (EPG, Electronic Program Guide), and the like. The tuner 12 is a tuner that selects a broadcast received by the antenna 11. The game input terminal 13 is a terminal for connecting a game machine and receiving an input of a game video from the game machine. The personal computer input terminal 14 is a terminal for connecting a personal computer and receiving an output image from the personal computer.

  The decoder 15 decodes the TV broadcast signal selected by the tuner 12, the signal input to the game input terminal 13, and the signal input to the personal computer input terminal 14, and is displayed on the liquid crystal panel 23. A decoder that acquires a video signal of a video, decodes a data broadcast signal of an electronic program guide (EPG) received by the antenna 11, and acquires video genre information included in the information obtained as a result. is there. Here, the video genre is genre information indicating the type and content of the video, such as “news / report”, “movie”, “animation / special effects”, “soccer”, “sumo / martial arts”, “game”, etc. is there.

  The brightness sensor 16 is a sensor that detects the brightness of the room in which the liquid crystal display device 10 is installed (brightness around the liquid crystal display device 10) and outputs a signal indicating the detected brightness. The remote control light receiving unit 17 is a processing unit that receives an infrared signal indicating the user's operation content from the remote control 27 when the user operates the remote control 27. Here, the remote controller 27 is an input device that accepts input of various types of information through user operations.

  The storage unit 18 is a storage device such as a memory. The storage unit 18 includes brightness correction setting information, a video genre / APL (Average Picture Level) conversion table 30, a video mode / brightness conversion table 31, a brightness / brightness correction value conversion table 32, a dimming function, which will be described later. A value / luminance correction value conversion table 33 and the like are stored. APL is the average value of the luminance of each pixel in the video signal for one frame. This APL is expressed as a percentage, and is 100% when the entire image is white, and 0% when the entire image is black.

  The luminance correction setting information includes information on video genre, video mode, room brightness, and user dimming value in order to correct the luminance of the backlight 25 (backlight luminance) set by the region luminance setting unit 20. It is information indicating whether or not to use. This brightness correction setting information is information set in advance by the user using the remote controller 27.

  Here, the video mode information is information on a mode in which the video image quality is preset. As the video mode, for example, “dynamic mode”, “standard mode”, “movie mode”, “game mode”, “output image display mode of personal computer”, and the like are set. The user can switch each video mode by operating the remote controller 27. The room brightness information is the room brightness information detected by the brightness sensor 16. The user dimming value information is screen brightness information set by the user.

  The video genre / APL conversion table 30 is data in which APL information is registered in association with video genre information. FIG. 2 is a diagram illustrating an example of the video genre / APL conversion table 30. Each APL is set as follows according to the video genre.

  FIG. 3 is a diagram for explaining the APL setting corresponding to each video genre. In order to set the APL, in each frequency distribution shown in FIGS. 3A to 3E, first, the total value of the frequencies of each APL is calculated, and the frequency of each APL is determined from the one with the larger APL. Are accumulated in order. Then, the APL value when the integrated value exceeds, for example, 30% of the total value is set as the APL value corresponding to each video genre, and is registered in the video genre / APL conversion table 30.

  For example, when the video genre is “news / report” (in the case of FIG. 3A), when the APL is 55%, the integrated value exceeds 30% of the total value, so the APL is set to 55%. Is done. Similarly, in the example of each movie genre of “movie”, “animation / special effects”, “soccer”, and “sumo / martial art” shown in FIGS. 3B to 3E, the APL of each movie genre is respectively , 34%, 50%, 50%, and 38%. In addition, although not shown in FIG. 3, the APL of the video genre of “game” is set to 60%, for example. This indicates that the possibility that the APL is 60% or less is 70%, and it can be said that the APL is 60% or less in most cases.

  Here, the ratio of the integrated value to the total value is 30%, but this ratio may be another value. Alternatively, the average value of APL may be set as the APL value of the video genre.

The backlight luminance correction based on the video genre is performed by, for example, the following formula 1.
(Backlight brightness after correction) = (Backlight brightness before correction)
× 100 / (value of APL corresponding to video genre) (Equation 1)
Here, “100 / (APL value corresponding to the video genre)” is a correction magnification for correction based on the video genre.

For example, the corrected backlight brightness of the video genre of “News / Report” with an APL of 55% is
(Backlight luminance after correction) = (Backlight luminance before correction) × 100/55
= (Backlight brightness before correction) x 1.82
Is calculated by

  An upper limit or lower limit is set for the correction magnification or the corrected backlight brightness. If the correction magnification or the corrected backlight brightness exceeds the upper limit or lower limit, the correction magnification or the corrected backlight brightness The backlight luminance may be set to the upper limit value or the lower limit value.

Here, the fact that the APL of the video genre of “News / Report” is 55% means that most of the APL values (70% in the example of FIG. 3) in the frequency distribution shown in FIG. The value is 55% or less. Therefore, it is assumed that 55% of the video is a white area and 45% is a black area (APL = 55%). Further, the maximum power that can be supplied to the backlight 25 is set, and the backlight luminance when the maximum power is supplied to the backlight 25 and all areas of the backlight 25 are lit in white is 500 cd / m ^2. Assume that

  FIG. 4 is a diagram showing the relationship between the maximum luminance that the backlight 25 can emit and APL. FIG. 5 is a diagram showing the relationship between the power supplied to the backlight 25 and the APL when the backlight 25 emits light with the maximum luminance. Here, the maximum power mentioned above is about 165 W as shown in FIG. The reason why the supply power is reduced when the APL is in the range of about 30% or less is to suppress the light emission of the backlight 25 for a dark image with a small white area.

  If 55% of the video is a white area and 45% is a black area, it is not necessary to supply power to the area of the backlight 25 corresponding to the black area that occupies 45% of the video. Thus, the maximum power can be used in the area of the backlight 25 corresponding to the white area occupying.

Here, the maximum luminance when the APL is 55% is 850 cd / m ² as shown in FIG. When the video genre is “news / report”, the backlight brightness after correction is calculated by multiplying the backlight brightness before correction by 1.82 (= 100/55) as described above. In the case where the backlight luminance exceeds 850 cd / m ² , the corrected backlight luminance is limited to 850 cd / m ² . However, even in this case, the backlight luminance is only slightly lowered, and no major video breakdown occurs. Thus, the brightness of the video can be effectively increased by using the information of APL.

In addition, in the “news / report” video genre, there may be a low possibility that a video having an APL of 55% or more appears. For example, it is assumed that an image having an APL of 70% appears, and 70% of the image is a white area and 30% is a black area. In FIG. 4, the maximum luminance when APL is 70% is 680 cd / m ² . When the APL is 70% compared to the case where the APL is 55%, the maximum luminance is small and the corrected backlight luminance is limited to a smaller value of 680 cd / m ² , but the white area is large, It's bright enough that it won't break up.

Similarly, in FIG. 2, the APL of the video genre of “game” is 60% means that when the frequency distribution as shown in FIG. 3 is generated, most of the APL (7 in the example of FIG. 3). %) Is a value of 60% or less. Therefore, it is assumed that 60% of the video is a white area and 40% is a black area (APL = 60%). Further, the maximum power that can be supplied to the backlight 25 is set, and the backlight luminance when the maximum power is supplied to the backlight 25 and all areas of the backlight 25 are lit in white is 500 cd / m ^2. Assume that

In this case, since it is not necessary to supply power to the area of the backlight 25 corresponding to the black area of the video, the maximum power can be used in the area of the backlight 25 corresponding to the white area that occupies 60% of the video. Become. The maximum luminance that the backlight 25 can emit when the APL is 60% is 800 cd / m ² from FIG.

Therefore, when the video genre is “game”, as described above, the backlight luminance before correction is multiplied by 1.67 (= 100/60) to calculate the backlight luminance after correction. When the backlight luminance of the backlight exceeds 800 cd / m ² , the corrected backlight luminance is limited to 800 cd / m ² . However, even in this case, the backlight luminance is only slightly lowered, and no major video breakdown occurs. Thus, the brightness of the video can be effectively increased by using the information of APL.

In the “game” video genre, a video with an APL of 60% or more may appear low. For example, it is assumed that an image having an APL of 70% appears, and 70% of the image is a white area and 30% is a black area. In FIG. 4, the maximum luminance when APL is 70% is 680 cd / m ² . Compared to the case where the APL is 55%, the maximum luminance is reduced when the APL is 70%, and the corrected backlight luminance is limited to a smaller value of 680 cd / m ² , but the white area is large, It's bright enough that it won't break up. The same can be said when the video genre is “movie”, “animation / special effects”, “soccer”, and “sumo / martial arts”.

  The video mode / brightness conversion table 31 is data in which backlight luminance information is registered in association with video mode information. FIG. 6 is a diagram showing an example of the video mode / luminance conversion table 31. Examples of the video mode include “dynamic mode”, “standard mode”, “movie mode”, “game mode”, and “output image display mode of personal computer”. A set value of backlight luminance is registered in advance for each video mode.

Correction of the backlight luminance based on the video mode is performed by the following equation 2.
(Backlight brightness after correction) = (Backlight brightness before correction)
× (Setting value of backlight brightness in dynamic mode)
/ (Set value of backlight luminance corresponding to video mode set by user) (Expression 2)
Here, “(set value of backlight luminance in the dynamic mode) / (set value of backlight luminance corresponding to the video mode set by the user)” is a correction magnification for correction based on the video mode.

For example, in the video mode / luminance conversion table 31 shown in FIG. 6, the backlight luminance of “dynamic mode” is registered as 450 (cd / m ² ), so that the correction is performed when the video mode is “standard mode”. The backlight brightness after
(Backlight luminance after correction) = (Backlight luminance before correction) × 450/240
= (Backlight brightness before correction) x 1.88
When the video mode is “movie mode”, the corrected backlight brightness is
(Backlight brightness after correction) = (Backlight brightness before correction)
× 450/200
= (Backlight brightness before correction) x 2.25
Is calculated by

In addition, when the video mode is “game mode” or “personal computer output image display mode”, the corrected backlight brightness is
(Backlight brightness after correction) = (Backlight brightness before correction)
× 450/270
= (Backlight brightness before correction) x 1.67
Is calculated by

  An upper limit or lower limit is set for the correction magnification or the corrected backlight brightness. If the correction magnification or the corrected backlight brightness exceeds the upper limit or lower limit, the correction magnification or the corrected backlight brightness The backlight luminance may be set to the upper limit value or the lower limit value.

  Here, the reciprocal of the correction magnification is a value indicating how low the backlight luminance is set by the user compared to the maximum value of the backlight luminance corresponding to each video mode. For example, when the user selects “standard mode”, the reciprocal value is 53.3% (= 240/450 × 100). The reciprocal value of 53.3% can be replaced when a value of 53.3% is registered as the APL value in the video genre / APL conversion table 30 of FIG. Therefore, as in the case of correcting the backlight luminance based on the video genre, the backlight luminance before correction is uniformly increased by 1.88 (= 100 / 53.3).

  The brightness / brightness conversion table 32 is data in which information on a backlight brightness correction value and a backlight brightness correction coefficient is registered in association with information on room brightness. FIG. 7 is a diagram illustrating an example of the brightness / luminance conversion table 32. Here, the backlight brightness correction value is a value used to calculate a reference backlight brightness B, which will be described later, and the backlight brightness correction coefficient is used to adjust the backlight brightness based on the brightness of the room. Value.

  As shown in FIG. 7, the brightness of the room is detected by the brightness sensor 16 in 256 levels from 0 to 255. The backlight luminance correction coefficient corresponding to the brightness not registered in the brightness / luminance conversion table 32 is interpolated using the backlight luminance correction coefficient corresponding to the brightness registered in the brightness / luminance conversion table 32. Calculated by performing processing.

The correction based on the brightness of the room is performed by, for example, the following Expression 3.
(Backlight brightness after correction) = (Backlight brightness before correction)
× (Backlight luminance correction coefficient corresponding to detected brightness) (Equation 3)
Here, the “backlight luminance correction coefficient corresponding to the detected brightness” is a correction magnification for correction based on the brightness of the room.

For example, in FIG. 7, when the brightness of the room is 56, the corrected backlight brightness is
(Backlight brightness after correction) = (Backlight brightness before correction) × 1.7
Is calculated by In this case, if the pre-correction of the backlight luminance is 200 cd / ^{m 2,} backlight luminance after the correction becomes 340 cd / ^{m 2} 1.7 times the pre-correction of the backlight luminance.

  As shown in FIG. 4, the maximum luminance that the backlight 25 can emit is limited by the value of APL. Therefore, when the corrected backlight luminance calculated by Equation 3 exceeds the maximum luminance corresponding to the APL of the video, the corrected backlight luminance is limited to the maximum luminance.

  Here, the reciprocal of the correction magnification is a value indicating how much the backlight luminance is set low (or high) depending on the brightness of the room. For example, when the brightness of the room is 56 and the backlight luminance correction coefficient is 1.7, the value of the reciprocal is 58.8% (= 1 / 1.7). The reciprocal value of 58.8% can be replaced when a value of 58.8% is registered as the APL value in the video genre / APL conversion table 30 of FIG. Therefore, the backlight luminance before correction is uniformly increased by 1.7 times (= 100 / 58.8).

  The dimming value / luminance correction value conversion table 33 is data in which information on the backlight luminance correction value and the backlight luminance correction coefficient is registered in association with the information on the user dimming value. FIG. 8 is a diagram illustrating an example of the dimming value / luminance conversion table 33. Here, the backlight luminance correction value is a value used for calculating a reference backlight luminance B described later, and the backlight luminance correction coefficient is used for adjusting the backlight luminance based on the user dimming value. Value.

As shown in FIG. 8, the user dimming value is set in 33 stages from -16 to 16. And the correction | amendment of the backlight brightness | luminance based on a user dimming value is correct | amended by the following formula | equation 4, for example.
(Backlight brightness after correction) = (Backlight brightness before correction)
× (Backlight luminance correction coefficient corresponding to user dimming value) (Equation 4)
Here, the “backlight luminance correction coefficient corresponding to the user dimming value” is a correction magnification for correction based on the user dimming value.

For example, in FIG. 8, when the user dimming value is −8, the corrected backlight luminance is
(Backlight brightness after correction) = (Backlight brightness before correction) × 1.5
Is calculated by In this case, if the backlight luminance before correction is 200 cd / m ² , the backlight luminance after correction is 300 cd / m ^{2 which} is 1.5 times the backlight luminance before correction.

  As shown in FIG. 4, the maximum luminance that the backlight 25 can emit is limited by the value of APL. Therefore, when the corrected backlight luminance calculated by the above equation 4 exceeds the maximum luminance corresponding to the APL of the video, the corrected backlight luminance is limited to the maximum luminance.

  Here, the reciprocal of the correction magnification is a value indicating how much the backlight luminance is set low (or high) by the user dimming value. For example, when the user dimming value is −8 and the backlight luminance correction coefficient is 1.5, the reciprocal value is 66.6% (= 1 / 1.5). The reciprocal value of 66.6% can be replaced when a value of 66.6% is registered as the APL value in the video genre / APL conversion table 30 of FIG. Therefore, the backlight luminance before correction is uniformly 1.5 times (= 100 / 66.6).

  Thus, in order to correct the backlight luminance set by local dimming, the video brightness is effectively set by using the information of the video genre, video mode, room brightness, and user dimming value. be able to. Further, unlike the conventional high-brightness local dimming, the total current value distributed to each area of the backlight 25 is not calculated, so that the lighting control of the backlight 25 can be speeded up by at least one frame. As a result, the frame memory for synchronizing the lighting control of the backlight 25 and the drive control of the liquid crystal panel 23 becomes unnecessary, and the apparatus can be simplified and the cost can be reduced.

  Returning to the description of FIG. 1, the microcomputer 19 acquires information for correcting the backlight luminance set by local dimming from the decoder 15, the brightness sensor 16, and the remote control light receiving unit 17, and the area luminance setting unit 20 It is a device that outputs to the LED control unit 21.

  Specifically, the microcomputer 19 receives the information on the video genre from the decoder 15 and refers to the video genre / APL conversion table 30 shown in FIG. Output to.

  Further, the microcomputer 19 receives information on the video mode set by the user using the remote controller 27 from the remote control light receiving unit 17 and corresponds to the video mode with reference to the video mode / brightness conversion table 31 shown in FIG. Information on the backlight luminance is output to the region luminance setting unit 20 and the LED control unit 21.

  Further, the microcomputer 19 receives a signal indicating the brightness of the room from the brightness sensor 16, and refers to the brightness / brightness conversion table 32 shown in FIG. 7 to correct the backlight brightness corresponding to the brightness of the room. Information on the value is output to the area luminance setting unit 20, and information on the backlight luminance correction coefficient is output to the LED control unit 21.

  Further, the microcomputer 19 receives information on the user dimming value set by the user using the remote controller 27 from the remote control light receiving unit 17, and refers to the dimming value / luminance conversion table 33 shown in FIG. Information on the backlight luminance correction value corresponding to the light value is output to the region luminance setting unit 20, and information on the backlight luminance correction coefficient is output to the LED control unit 21.

  The area luminance setting unit 20 is a processing unit that sets the backlight luminance in each area of the backlight 25 based on the luminance information of each area of the video by local dimming. FIG. 9 is a diagram for explaining luminance setting processing by local dimming. FIG. 9 shows an example in which the video is divided into eight regions.

First, the region luminance setting unit 20 detects the maximum luminance values Ymax _{1 to} Ymax ₈ of each pixel in each region in one frame of the video for each of the regions _{1 to 8} . Then, the region luminance setting unit 20 selects the largest value among the maximum values Ymax _{1 to} Ymax ₈ and calculates the ratio of each value to that value. For example, if Ymax ₈ is selected, the above ratio is calculated as Ymax ₁ / Ymax ₈ , Ymax ₂ / Ymax ₈ ,..., Ymax ₇ / Ymax ₈ , 1 (= Ymax ₈ / Ymax ₈ ).

Then, the area luminance setting unit 20 sets the backlight luminance of the areas 1 to 8 to A × Ymax ₁ / Ymax ₈ , A × Ymax ₂ / Ymax ₈ ,..., A × Ymax ₇ / Ymax ₈ , A, respectively. Set to (cd / m ² ). Here, A is a predetermined value.

  When the video mode is set by the user, when the user sets the backlight brightness according to the brightness of the room detected by the brightness sensor 16, or when the user dimming value is set by the user. When set, the area brightness setting unit 20 sets the backlight brightness corresponding to the video mode, the backlight brightness correction value corresponding to the room brightness, or the backlight brightness correction value corresponding to the user dimming value. Information is acquired from the microcomputer 19 and the reference backlight luminance B is calculated by adding them.

For example, in FIGS. 6 to 8, when the video mode is “standard mode”, the room brightness is 56, and the user dimming value is 8, this reference backlight luminance B is 220 (cd / m). ² ) (= 240-100 + 80).

Then, the area luminance setter 20, each backlight luminance areas 1-8, _{respectively, B × Ymax 1 / Ymax 8} , B × Ymax 2 / Ymax 8, ···, B × Ymax 7 / Ymax 8, Set to B (cd / m ² ). FIG. 9 shows a case where the reference backlight luminance B is 220 (cd / m ² ).

  Returning to the description of FIG. 1, the LED control unit 21 may include APL information corresponding to the video genre, backlight luminance information corresponding to the video mode, backlight luminance correction coefficient information corresponding to the room brightness, or The backlight luminance correction coefficient information corresponding to the user dimming value is received from the microcomputer 19 and the backlight luminance of each area of the backlight 25 set by the area luminance setting unit 20 is corrected based on the received information. It is a processing unit.

  The LED control unit 21 generates a control signal for controlling the LED driver 24 using the corrected backlight luminance information. Then, the LED control unit 21 outputs the generated control signal to the LED driver 24, causes the LED driver 24 to drive the backlight 25 so that the backlight luminance becomes the corrected backlight luminance, and turns on the backlight 25. Is controlled for each region.

  When the LED control unit 21 is set by the user to correct the backlight luminance using the video genre information, the LED control unit 21 acquires the APL value corresponding to the video genre from the microcomputer 19, and “ 100 / (APL value corresponding to video genre) "is calculated.

  In addition, the LED control unit 21 sets the setting value of the backlight luminance in the dynamic mode and the video set by the user when the user sets the backlight luminance correction using the video mode information. The setting value of the backlight luminance corresponding to the mode is acquired from the microcomputer 19, and “(the setting value of the backlight luminance in the dynamic mode) / (the setting value of the backlight luminance corresponding to the video mode set by the user) in Expression 2 ) ”Is calculated.

  In addition, when the user has set the backlight brightness correction using the information on the brightness of the room, the LED control unit 21 sets “backlight brightness correction corresponding to the detected brightness” in Expression 3. The value of “coefficient” is acquired from the microcomputer 19. In addition, the LED control unit 21 sets “backlight luminance correction corresponding to the user dimming value” in Expression 4 when the user has set the backlight luminance correction using the information on the user dimming value. Value) / (backlight luminance before correction)) ”is acquired from the microcomputer 19.

  Then, the LED control unit 21 calculates the correction magnification by multiplying each value obtained as described above, and uniformly applies the correction magnification to the backlight luminance of each region set by the region luminance setting unit 20. By combining them, a correction value of the backlight luminance is calculated for each area of the backlight 25. Thereafter, the LED control unit 21 generates a control signal for controlling lighting of each area of the backlight 25 using the calculated correction value, and outputs the generated control signal to the LED driver 24.

  FIG. 10 is a diagram for explaining calculation of a correction value for backlight luminance. FIG. 10 shows the backlight luminance of each region after the backlight luminance set as shown in FIG. 9 is corrected by the correction magnification. As shown in FIG. 10, the backlight luminance of each region is set higher than the backlight luminance of each region set by the region luminance setting unit 20, and a brighter video display is realized.

  Returning to the description of FIG. 1, the timing controller 22 receives the video signal output from the decoder 15 via the region luminance setting unit 20, and based on the video signal, the source driver and the gate driver of the liquid crystal panel 23. A device that transmits a control signal for controlling the video display timing. The liquid crystal panel 23 is a display device that displays video by being driven by a source driver and a gate driver.

  The LED driver 24 is a driver that controls the lighting of each area of the backlight 25 by receiving a control signal from the LED control unit 21 and supplying a current to each LED included in the backlight 25. The backlight 25 is a direct type LED backlight in which a large number of LEDs are arranged. The LED provided in the backlight 25 is supplied with current from the LED driver 24 and lights up with backlight brightness corresponding to the current value for each region.

  Below, an example of the process sequence of the backlight lighting process which concerns on this invention is demonstrated. In this backlight lighting process, first, a local dimming process is performed on the video signal, and the luminance of each area of the backlight is set. Thereafter, the set luminance is corrected based on information such as the video genre, video mode, room brightness, user dimming value, and the like, and lighting of the backlight 25 is controlled based on the corrected luminance value. Hereinafter, the backlight lighting process will be described in more detail.

  11 and 12 are flowcharts showing an example of the processing procedure of the backlight lighting processing according to the present invention. As shown in FIG. 11, the area luminance setting unit 20 of the liquid crystal display device 10 acquires the video signal output by the decoder 15 and executes local dimming processing on the acquired video signal (step S101). Specifically, the area luminance setting unit 20 sets the backlight luminance of each area of the backlight 25 corresponding to each area of the video, using information on the luminance of each area of the video displayed by the video signal. .

  Then, as described with reference to FIG. 9, the region luminance setting unit 20 executes the correction of the backlight luminance based on the reference backlight luminance (Step S <b> 102). Thereafter, the LED control unit 21 reads brightness correction setting information from the storage unit 18 via the microcomputer 19 (step S103). Whether the luminance correction setting information uses information on the video genre, video mode, room brightness, and user dimming value in order to correct the backlight luminance set by the region luminance setting unit 20. Information on whether or not is registered in advance.

  Then, the LED control unit 21 refers to the luminance correction setting information and determines whether or not the video genre information is used for correcting the backlight luminance (step S104). When the information on the video genre is used (YES in step S104), the LED control unit 21 acquires the APL information corresponding to the video genre of the currently viewed video from the microcomputer 19 (step S105). Then, the LED control unit 21 calculates a correction magnification (“100 / (APL value corresponding to the video genre)” in Expression 1) based on the video genre (step S106).

  After the process of step S106 or when the video genre information is not used in step S104 (NO in step S104), the LED control unit 21 refers to the brightness correction setting information and corrects the backlight brightness. It is determined whether or not video mode information is used (step S107).

  When the video mode information is used (YES in step S107), the LED control unit 21 acquires backlight luminance information corresponding to the currently set video mode from the microcomputer 19 (step S108). Then, the LED control unit 21 sets the correction magnification of the correction based on the video mode (“(the backlight luminance setting value in the dynamic mode) in Equation 2) / (the backlight luminance setting value corresponding to the video mode set by the user). ) ") Is calculated (step S109).

  After the process of step S109 or when the video mode information is not used in step S107 (NO in step S107), as shown in FIG. 12, the LED control unit 21 refers to the brightness correction setting information. Then, it is determined whether or not the information on the brightness of the room is used for correcting the backlight luminance (step S110).

  When the information on the brightness of the room is used (YES in step S110), the LED control unit 21 obtains the information on the backlight brightness correction coefficient corresponding to the brightness of the room detected by the brightness sensor 16 from the microcomputer 19. (Step S111). Then, the LED control unit 21 sets the acquired information as a correction magnification of correction based on room brightness (“backlight luminance correction coefficient corresponding to detected brightness” in Expression 3) (step S112).

  After the process of step S112 or when the information on the brightness of the room is not used in step S110 (NO in step S110), the LED control unit 21 refers to the brightness correction setting information and determines the backlight brightness. It is determined whether or not the user dimming value information is used for correction (step S113).

  When the user dimming value information is used (YES in step S113), the LED control unit 21 acquires the backlight luminance correction coefficient information corresponding to the user dimming value set by the user from the microcomputer 19. (Step S114). Then, the LED control unit 21 sets the acquired information as a correction magnification for correction based on the user dimming value (“backlight luminance correction coefficient corresponding to the user dimming value” in Expression 4) (step S115).

  After the process of step S115 or when the user dimming information is not used in step S113 (NO in step S113), the LED control unit 21 calculates the product of the calculated or set correction magnifications ( Step S116). Here, when an upper limit value or a lower limit value is set in advance as the product value of each correction magnification and the product exceeds the upper limit value or the lower limit value, the LED control unit 21 sets the product to the upper limit value. Or it is good also as setting to a lower limit. Thereafter, the LED control unit 21 corrects the backlight luminance of each region by multiplying the calculated product by the backlight luminance of each region set by the region luminance setting unit 20 (step S117).

  Subsequently, the LED control unit 21 controls the lighting of the backlight 25 based on the corrected backlight luminance information of each region (step S118). Specifically, the LED control unit 21 generates a control signal for controlling the LED driver 24 and outputs the control signal to the LED driver 24. Then, the LED control unit 21 lights each region of the backlight 25 so that the backlight luminance of each region becomes the corrected backlight luminance. Thereafter, the backlight lighting process ends.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to embodiment mentioned above, A various deformation | transformation and correction are possible within the range which does not deviate from the summary of this invention. For example, in the above embodiment, a frame memory for synchronizing the lighting control of the backlight 25 and the drive control of the liquid crystal panel 23 is not required, and the conventional apparatus can be simplified and reduced in cost. Although the high-brightness local dimming is not performed, the liquid crystal display device 10 may perform the switching between the backlight lighting process by the conventional high-brightness local dimming and the backlight lighting process described in the above embodiment. Good. In this case, the LED control unit 21 may receive a process switching request performed by the user operating the remote controller 27 and execute the backlight lighting process specified by the user.

  In the above embodiment, the APL value corresponding to each video genre is registered in advance in the video genre / APL conversion table 30 shown in FIG. 2, and each area of the backlight 25 is used by using the APL value. However, based on the APL information of the video displayed in the past, the APL information corresponding to each video genre is updated, and the backlight 25 is controlled based on the updated APL information. It is good also as controlling lighting of each area | region for every area | region.

  Specifically, the microcomputer 19 receives video genre information and video signals from the decoder 15, and accumulates video APL information in the storage unit 18 for each video genre. Then, the microcomputer 19 determines the APL value corresponding to each video genre from the frequency distribution as shown in FIG. 3 by the method described with reference to FIG. 3, and uses the APL value to determine the video genre. Update the APL value registered in the APL conversion table 30. The LED control unit 21 controls lighting of each area of the backlight 25 using the updated APL value. As a result, the characteristics of each video genre are more accurately reflected in the APL, so that the brightness of the video can be increased more effectively.

  In the above embodiment, the region luminance setting unit 20 sets the backlight luminance in each region of the backlight 25 by local dimming, and the LED control unit 21 sets the backlight 25 set by the region luminance setting unit 20. The backlight brightness of each region is corrected, but the LED control unit 21 performs only local dimming when the video is input to the game input terminal 13 and does not correct the backlight brightness. Also good. For example, in this case, the LED control unit 21 can set the correction magnification to be multiplied by the backlight luminance set by the region luminance setting unit 20 to 1 so that the backlight luminance is not corrected.

  Accordingly, when the game machine is connected to the liquid crystal display device 10 and the liquid crystal display device 10 is used as a monitor of the game machine, the backlight luminance can be appropriately adjusted so as to be suitable for display of the video of the game. .

  Similarly, when the video is input to the personal computer input terminal 14, the LED control unit 21 may perform only local dimming and not perform backlight luminance correction. Also in this case, the LED control unit 21 can prevent the backlight luminance from being corrected by setting the correction magnification to be multiplied by the backlight luminance set by the region luminance setting unit 20 to 1.

  Accordingly, when the personal computer is connected to the liquid crystal display device 10 and the liquid crystal display device 10 is used as a monitor of the personal computer, the backlight luminance can be appropriately adjusted so as to be suitable for the display of the image of the personal computer. it can. In particular, the above adjustment is useful when the liquid crystal display device 10 is used as a monitor of a personal computer because a user plays a game for a personal computer.

  Furthermore, in the above-described embodiment, when the video genre is “game”, the luminance of the backlight is increased. However, the luminance of an area that does not need to be increased may be decreased.

  Specifically, when the area luminance setting unit 20 and the LED control unit 21 detect that the genre of the video is “game”, the luminance of a predetermined area of the backlight after the detection is made. The brightness of a predetermined area of the backlight before the detection is made may be made smaller. Here, the predetermined area is an area where the gradation of the video signal is smaller than a predetermined value.

  For example, the area luminance setting unit 20 and the LED control unit 21 may increase the luminance of the backlight in an area where the gradation of the video signal is equal to or greater than a predetermined value by 1.5 times. The luminance of the backlight in the area smaller than the value may be increased by 1 / 1.5.

  If the backlight brightness in a low gradation area in a dark scene increases, people will feel uncomfortable or noise will be noticeable. However, as described above, the luminance in the area where the gradation of the video signal is smaller than the specified value. Such drawbacks can be eliminated by lowering.

  The area luminance setting unit 20 sets the backlight luminance in each area of the backlight 25 by local dimming, and the LED control unit 21 multiplies the backlight luminance by a correction magnification to correct the backlight luminance. However, the LED control unit 21 multiplies the backlight luminance by a smaller correction magnification than the magnification A / S of the predetermined current allowable value A with respect to the total drive current S of the backlight 25, and the backlight luminance. May be corrected.

  This makes it possible to ensure that the drive current of the backlight 25 is within a predetermined allowable current value when adjusting the backlight brightness so as to be suitable for video display.

DESCRIPTION OF SYMBOLS 10 ... Liquid crystal display device, 11 ... Antenna, 12 ... Tuner, 15 ... Decoder, 16 ... Brightness sensor, 17 ... Remote control light-receiving part, 18 ... Memory | storage part, 19 ... Microcomputer, 20 ... Area brightness setting part, 21 ... LED control , 22 ... Timing controller, 23 ... Liquid crystal panel, 24 ... LED driver, 25 ... Backlight, 26 ... Backlight controller, 27 ... Remote control, 30 ... Video genre / APL conversion table, 31 ... Video mode / brightness conversion table 32 ... Brightness / luminance correction value conversion table, 33 ... Dimming value / luminance correction value conversion table.

Claims (17)

A liquid crystal display device for displaying images,
The first luminance of each area of the backlight that illuminates each area of the video is determined for each area of the backlight based on the luminance information of each area of the video, and the first luminance of each area is determined. Further, a second magnification of each area of the backlight is set by uniformly multiplying a constant magnification set according to the genre of the video, and each of the backlights is set using the second luminance of each area. A backlight control unit that controls lighting of the area for each area of the backlight;
A liquid crystal display device comprising:   The liquid crystal display according to claim 1, wherein the backlight control unit controls lighting of each area of the backlight for each area of the backlight when the genre of the video is a game. apparatus.   2. The constant magnification is smaller than a magnification of a predetermined allowable current value with respect to a total value of drive currents of the backlight when each region of the backlight is lit at a first luminance. Or a liquid crystal display device according to 2;   The backlight control unit further uniformly multiplies the first luminance of each area of the backlight by a constant magnification set based on the brightness information around the device itself, and The liquid crystal display device according to claim 1, wherein the second luminance is set.   The backlight control unit further uniformly multiplies the first luminance of each region of the backlight by a constant magnification set based on information on the luminance setting value input by operating the input device, 5. The liquid crystal display device according to claim 1, wherein a second luminance of each region of the backlight is set.   A storage unit for storing APL information corresponding to the video genre in association with the video genre, wherein the backlight control unit searches the APL information corresponding to the video genre, and The liquid crystal display device according to claim 1, wherein the constant magnification is set based on information on APL obtained as a result.   The liquid crystal display device according to claim 6, wherein the backlight control unit updates the APL information stored in the storage unit based on the APL information of the video displayed in the past.   The said backlight control part sets the said fixed magnification to 1 when the said image | video is the image | video input into the game input terminal, The one of Claims 1-7 characterized by the above-mentioned. Liquid crystal display device.   The said backlight control part sets the said fixed magnification to 1 when the said image | video is the image | video input into the input terminal for personal computers, The any one of Claims 1-7 characterized by the above-mentioned. Liquid crystal display device.   The backlight control unit further uniformly multiplies the first luminance of each area of the backlight by a constant magnification set based on information of a video mode in which the image quality of the video is set in advance, and The liquid crystal display device according to claim 1, wherein a second luminance of each area of the light is set.   The liquid crystal display device according to claim 10, wherein the backlight control unit sets a second luminance of each region of the backlight when the video mode is a game mode.   11. The liquid crystal according to claim 10, wherein the backlight control unit sets the second luminance of each region of the backlight when the video mode is an output image display mode of a personal computer. Display device.   The liquid crystal display device according to claim 10, wherein the backlight control unit increases a second luminance of each region of the backlight more than a first luminance of each region of the backlight. A liquid crystal display device for displaying images,
The first luminance of each area of the backlight that illuminates each area of the video is determined for each area of the backlight based on the luminance information of each area of the video, and the first luminance of each area is determined. In addition, a second magnification of each area of the backlight is set by uniformly multiplying a constant magnification set in accordance with the brightness of the surroundings of the device, and the backlight using the second luminance of each area. A backlight control unit for controlling the lighting of each area for each area of the backlight,
A liquid crystal display device comprising: A liquid crystal display device for displaying images,
The first luminance of each area of the backlight that illuminates each area of the video is determined for each area of the backlight based on the luminance information of each area of the video, and the first luminance of each area is determined. Further, the second brightness of each area of the backlight is set by uniformly multiplying a constant magnification set according to the information of the brightness setting value input by operating the input device, and the second brightness of each area is set. A backlight control unit that controls lighting of each area of the backlight for each area of the backlight using a luminance of 2;
A liquid crystal display device comprising: A liquid crystal display device for displaying images,
The first luminance of each area of the backlight that illuminates each area of the video is determined for each area of the backlight based on the luminance information of each area of the video, and the first luminance of each area is determined. Further, the second luminance of each area of the backlight is set by uniformly multiplying a constant magnification set according to the type of the input terminal to which the video is input, and the second luminance of each area is used. A backlight control unit that controls lighting of each area of the backlight for each area of the backlight,
A liquid crystal display device comprising: A liquid crystal display device for displaying images,
The first luminance of each area of the backlight that illuminates each area of the video is determined for each area of the backlight based on the luminance information of each area of the video, and the first luminance of each area is determined. In addition, the second luminance of each area of the backlight is set by uniformly multiplying a constant magnification set in accordance with the information of the video mode in which the image quality of the video is set in advance, and the second luminance of each area is set. A backlight control unit for controlling lighting of each area of the backlight for each area of the backlight using luminance;
A liquid crystal display device comprising:

Images