WO2024075359A1 - Liquid-crystal display device, liquid-crystal display method, and program - Google Patents

Abstract

The purpose of the present invention is to provide a liquid-crystal display device, a liquid-crystal display method, and a program which make it possible to reduce flickering.　Provided is a liquid-crystal display device which controls a light source of backlight, wherein the liquid-crystal display device is configured to reduce flickering caused by the difference in liquid crystal response speed between pixels of which pixel values increase and pixels of which pixel values decrease at the time of transition from a first frame to a second frame, and comprises a correction data acquisition unit and a light source control unit. The correction data acquisition unit is configured to acquire, on the basis of the pixel values of the first and second frames, correction data for reducing the occurrence of flicking. The light source control unit is configured to acquire a backlight correction value on the basis of the correction data, wherein the backlight correction value is used for controlling the light source of backlight in a predetermined period between the first and second frames.

Description

Liquid crystal display device, liquid crystal display method, and program

The present invention relates to a liquid crystal display device, a liquid crystal display method, and a program.

When a frame displayed on a liquid crystal display device changes, the pixel value (brightness) of each pixel changes according to the frame being displayed. Here, since the response speed of pixels whose pixel values increase differs from the response speed of pixels whose pixel values decrease, flicker occurs in the liquid crystal display device when the frame changes, which can lead to a decrease in image quality (see, for example, Patent Document 1).

US Patent Application Publication No. 2011/0199287

The degree to which flicker occurs varies depending on the frame displayed on the LCD display device, but for example, flicker is likely to occur in a frame called a dot mesh, which is an alternating arrangement of white and black pixels.

The present invention was made in consideration of these circumstances, and aims to provide a liquid crystal display device, a liquid crystal display method, and a program that can reduce flicker.

According to the present invention, the following liquid crystal display device is provided.
[1] A liquid crystal display device that controls a backlight as a light source, the liquid crystal display device being configured to reduce flicker caused by a difference in liquid crystal response speed between pixels whose pixel values increase and pixels whose pixel values decrease during a transition from a first frame to a second frame, the liquid crystal display device comprising: a correction data acquisition unit; and a light source control unit, the correction data acquisition unit being configured to acquire correction data for reducing the occurrence of the flicker based on the pixel values of the first and second frames, the light source control unit being configured to acquire a backlight correction value based on the correction data, and the backlight correction value being used for the light source control of the backlight during a predetermined period between the first and second frames.

In the present invention, the light source control unit is configured to obtain a backlight correction value based on correction data for reducing the occurrence of flicker, and when a frame is displayed, the backlight is driven at a setting value that takes into account this backlight correction value, thereby reducing flicker.

Various embodiments of the present invention will be described below. The embodiments described below can be combined with each other.
[2] A liquid crystal display device as described in [1], wherein the correction data acquisition unit acquires the correction data using a liquid crystal response characteristic in which a pixel value of a first frame and a pixel value of a second frame are associated, and the liquid crystal response characteristic is a liquid crystal response speed or a liquid crystal response time.
[3] A liquid crystal display device as described in [2], wherein the correction data acquisition unit acquires the correction data using an estimated pixel value based on the liquid crystal response characteristics, the estimated pixel value being a pixel value at an intermediate timing, and the intermediate timing being a timing between the first and second frames.
[4] A liquid crystal display device according to any one of [1] to [3], wherein the light source control unit is configured to obtain the backlight correction value to be applied to pixels in the pixels within the region based on the correction data of the pixels within the region, and the pixels within the region are composed of a plurality of pixels included in a predetermined region of a first and second frame.
[5] A liquid crystal display device as described in [4], wherein the correction data acquisition unit is configured to acquire the correction data based on a difference between first and second statistical values, the first statistical value being a statistical value based on pixel values of the plurality of pixels in the region in a first frame, and the second statistical value being a statistical value based on pixel values of the plurality of pixels in the region at an intermediate timing, and the intermediate timing being a timing between the first and second frames.
[6] The liquid crystal display device according to [5], wherein the statistical value is an average value, a median value, or a value obtained based on a histogram.
[7] A liquid crystal display device as described in [4], wherein the correction data acquisition unit is configured to extract a specific pixel from among the pixels within the region, and is configured to acquire the correction data for the extracted specific pixel, and the light source control unit is configured to acquire the backlight correction value based on the correction data for the specific pixel.
[8] A liquid crystal display device according to any one of [4] to [7], wherein the correction data acquisition unit is configured to acquire an amount of flicker for each of the predetermined regions, and is configured to determine whether or not to use the correction data and the backlight correction value for the predetermined regions based on the amount of flicker, and the amount of flicker corresponds to a degree to which the flicker occurs in the predetermined regions during a transition from a first frame to a second frame.
[9] The liquid crystal display device according to any one of [1] to [8], wherein the first and second frames are dot mesh images.
[10] A liquid crystal display device according to any one of [1] to [9], wherein the light source control is local dimming control, and the backlight correction value is used for the local dimming control of the backlight corresponding to at least a pixel including a pixel of interest during a predetermined period between a first frame and a second frame.
[11] A liquid crystal display method for controlling a backlight as a light source, the liquid crystal display method reducing flicker caused by a difference in liquid crystal response speed between pixels whose pixel values increase and pixels whose pixel values decrease during a transition from a first frame to a second frame, the method comprising: a correction data acquisition step; and a backlight correction value acquisition step, in which correction data for reducing the occurrence of the flicker is acquired based on pixel values of the first and second frames, and in which a backlight correction value is acquired based on the correction data, the backlight correction value is used for the light source control of the backlight during a predetermined period between the first and second frames.
[12] A program for causing a computer to execute the liquid crystal display method according to [11].

FIG. 1 is a schematic diagram showing a liquid crystal display device 100 according to an embodiment of the present invention and an output device 200 that outputs a video signal. FIG. 2 is a functional block diagram of the liquid crystal display device 100 shown in FIG. FIG. 3 shows frame F1 as the previous frame. FIG. 4 shows pixel values at each coordinate of the frame F1 shown in FIG. FIG. 5 shows frame F2 as the subsequent frame. FIG. 6 shows pixel values at each coordinate of the frame F2 shown in FIG. FIG. 7 is an example of a look-up table (LUT) that associates pixel values of a previous frame with pixel values of a subsequent frame. FIG. 8 shows pixel values at each coordinate at intermediate timing. FIG. 9 is a graph for explaining how the pixel value of each coordinate (here, coordinate (1, 1)) is estimated to change over time. FIG. 10 is a flowchart illustrating various calculation steps when obtaining the backlight correction value Bc. Figures 11A to 11C show frames F1 and F2 that are different in the likelihood of flicker occurring. Frame F1 in Figures 11A to 11C is the same, and frame F2 in Figures 11A to 11C is different. Figure 11A shows the case in Figures 11A to 11C where flicker is most likely to occur. Figure 11B shows the case where flicker occurs slightly, and Figure 11C shows the case where flicker is least likely to occur among Figures 11A to 11C. Fig. 12A shows a transition line G of the average estimated pixel value when pixel values transition as in Fig. 11A. Fig. 12A shows differences Ar1 to Ar9 corresponding to the differences between the transition line G of the average estimated pixel value and a reference line RL passing through the timing of the subsequent frame. Fig. 12B shows a transition line G of the average estimated pixel value when pixel values transition as in Fig. 11B. Fig. 12C shows a transition line G of the average estimated pixel value when pixel values transition as in Fig. 11C. FIG. 13 is a flowchart illustrating various calculation steps when obtaining the backlight correction value Bc according to the first modification of the embodiment. FIG. 14 is a flowchart illustrating various calculation steps when acquiring the backlight correction value Bc according to the method 1 of the second modified example of the embodiment. Fig. 15A shows a predetermined region Rg of frame F1 as a previous frame and a predetermined region Rg of frame F2 as a subsequent frame, which are used in method 1 of modified example 2 of the embodiment. Fig. 15B shows a difference D in pixel values between frames F1 and F2. Fig. 15C shows the liquid crystal response characteristic (liquid crystal response time) of each pixel calculated from the LUT. Fig. 15D shows an estimated transition amount of pixel values of each pixel at intermediate timing. Fig. 15E shows an ideal value of the transition amount of pixel values of each pixel at intermediate timing. Fig. 15F shows insufficient transition amount data. FIG. 16 shows a straight line L1 for explaining how the pixel value of each coordinate (here, coordinate (2, 2)) is estimated to change over time, and a straight line L2 showing the ideal transition of each coordinate (here, coordinate (2, 2)). FIG. 17 is a functional block diagram of a liquid crystal display device 100 according to the fifth modification of the embodiment.

Below, an embodiment of the present invention will be explained using the drawings. The various features shown in the embodiment shown below can be combined with each other. Furthermore, each feature can be an invention independently.

1. Description of Overall Configuration The overall configuration of a liquid crystal display device 100 according to an embodiment will be described. In the embodiment, the liquid crystal display device 100 is communicably connected to an output device 200 as shown in FIG. 1. The output device 200 is an information processing device (e.g., a personal computer) and is configured to be able to output a video signal F. In the embodiment, the liquid crystal display device 100 is described as acquiring the video signal F from the output device 200 as an external device, but the present invention is not limited to this. The video signal F may be stored in advance in the liquid crystal display device 100, and the liquid crystal display device 100 may process the video signal F.

In the embodiment, the liquid crystal display device 100 is composed of a liquid crystal monitor. As shown in Fig. 2, the liquid crystal display device 100 includes a frame calculation processing unit 1, a correction data acquisition unit 2, a local dimming control unit 3 as a light source control unit, a memory 4, a liquid crystal driving circuit 5, a backlight driving circuit 6, and a liquid crystal display unit 7 having a liquid crystal panel 7A and a backlight 7B. The memory 4 stores data used in the processing of the correction data acquisition unit 2.
Each component of the liquid crystal display device 100 may be realized by software or hardware. When realized by software, various functions can be realized by a CPU executing a computer program. The program may be stored in a built-in storage unit or a computer-readable non-transient recording medium. In addition, the program stored in an external storage unit may be read and realized by so-called cloud computing. When realized by hardware, it can be realized by various circuits such as an ASIC, an FPGA, or a DRP (Dynamically Reconfigurable Processor). In this embodiment, various information and concepts including the same are handled, but these are represented by high and low signal values as a binary bit collection consisting of 0 or 1, and communication and calculation can be performed by the above-mentioned software or hardware aspects.

The liquid crystal display device 100 has a function for acquiring a backlight correction value Bc used when driving the backlight 7B in order to reduce flicker. Here, flicker is flickering that occurs in the liquid crystal display unit 7 due to pixel response delays when frames transition. In other words, flicker corresponds to a gap in pixel values (luminance) occurring between previous and subsequent frames due to the difference in the liquid crystal response speed of a pixel whose pixel value (luminance) increases and the liquid crystal response speed of a pixel whose pixel value (luminance) decreases when frames transition. The backlight correction value Bc described above makes it possible to reduce this gap.

Here, a frame transition corresponds to a transition from a frame of any timing (an example of a first frame) to a frame of the next timing (an example of a second frame).
Moreover, the pixel response delay means that there is a difference in response between pixels depending on the operation of the pixels of the liquid crystal display unit 7. In this embodiment, the liquid crystal display unit 7 will be described as having a response speed slower when the pixel value of each pixel of the liquid crystal display unit 7 increases than when the pixel value of each pixel of the liquid crystal display unit 7 decreases. In other words, when a frame transitions, a pixel whose pixel value decreases reaches a desired pixel value more quickly than a pixel whose pixel value increases. This embodiment is not limited to this, and can also be applied to a case where the response speed of each pixel of the liquid crystal display unit 7 when the pixel value of each pixel of the liquid crystal display unit 7 decreases is slower than the response speed of each pixel of the liquid crystal display unit 7 when the pixel value of each pixel of the liquid crystal display unit 7 increases.
In the embodiment, an increase in pixel value refers to a pixel value (relatively low value) of a pixel at any coordinate in a frame at any timing (an example of a first frame) increasing to a pixel value (relatively high value) of a pixel at the same coordinate in a frame next to the given frame (an example of a second frame). Similarly, a decrease in pixel value refers to a pixel value (relatively high value) of a pixel at any coordinate in a frame at any timing decreasing to a pixel value (relatively low value) of a pixel at the same coordinate in a frame next to the given frame.

The liquid crystal display device 100 obtains the above-mentioned backlight compensation value Bc using a pair of consecutive frames. For example, assume that the video signal F displays frames in the order of frame F1, frame F2, frame F3, frame F4, and so on. In this case, the liquid crystal display device 100 obtains the backlight compensation value Bc to be used in the period between frames F1 and F2 using frames F1 and F2. Similarly, the liquid crystal display device 100 obtains the backlight compensation value Bc to be used in the period between frames F2 and F3 using frames F2 and F3, and also obtains the backlight compensation value Bc to be used in the period between frames F3 and F4 using frames F3 and F4.

The video signal F has frames F1, F2, F3, F4, etc. in chronological order. However, in the following description of the configuration of each component, for the sake of convenience, the explanation will focus on various calculations using an arbitrary frame F1 and frame F2, which is the next frame of the arbitrary frame F1.
Note that since frames F1 and F2 are successive frames in time series, frame F1 may be referred to as the previous frame and frame F2 as the next frame. Frame F1, which is the previous frame, and frame F2, which is the next frame, are examples of the first and second frames. Similarly, frame F2, which is the previous frame, and frame F3, which is the next frame, are also examples of the first and second frames, and frame F3, which is the previous frame, and frame F4, which is the next frame, are also examples of the first and second frames.

2. Description of each component 2-1 Frame calculation processing unit 1
The frame calculation processing section 1 has a difference calculation function and a statistical value calculation function.

Difference calculation function (step S1 in FIG. 10: difference acquisition step)
The difference calculation function is a function that acquires a video signal F and acquires a difference D between pixel values (tone values) of a pair of frames in the video signal F. In the embodiment, the pixel value difference D is acquired for each coordinate of the previous and next frames (step S1 in FIG. 10: difference acquisition step). Note that, in the embodiment, the pixel value (tone value) is described as having a value of 0 to 255 (8 bits), but is not limited to this.
The pixel values of each pixel in the frame F1 shown in FIG. 3 are as shown in FIG. 4, and are, for example, 30 at the coordinates (1, 1) and 150 at the coordinates (2, 1). The pixel values of each pixel in the frame F2 shown in FIG. 5 are as shown in FIG. 6, and are, for example, 90 at the coordinates (1, 1) and 35 at the coordinates (2, 1). The coordinates (x, y) are defined by the position in the x direction and the position in the y direction perpendicular to the x direction. For example, the difference D between the pixel values at the coordinates (1, 1) of the previous and next frames is 90-30=60, and the difference D between the pixel values at the coordinates (2, 1) of the previous and next frames is 35-150=-115. In this way, the frame calculation processing unit 1 calculates the difference between the pixel values of each coordinate for the previous and next frames, the frames F1 and F2.

Statistical value calculation function (step S2 in FIG. 10: first statistical value acquisition step)
The statistical value calculation function is a function for obtaining statistical values (average values in this embodiment) of pixel values of a predetermined region Rg in previous and next frames (frames F1 and F2). First, the predetermined region Rg will be described.

In this embodiment, the liquid crystal of the liquid crystal display unit 7 is controlled for each pixel, whereas the backlight 7B is controlled for each predetermined region Rg. In other words, the predetermined region Rg is significant as a control unit for local dimming control. Note that local dimming control refers to control in which a set value is changed for each area, rather than controlling the entire area of the liquid crystal display unit 7 with a uniform set value. Local dimming control is an example of light source control.
As described later, this embodiment is configured to obtain a backlight correction value Bc based on correction data Ec, and drive the backlight 7B based on the backlight correction value Bc to suppress flicker. Here, in this embodiment, to suppress flicker, a case will be described as an example in which a configuration is provided in which the backlight correction value Bc is obtained after performing local dimming control, which is an example of light source control, but local dimming control is not a required configuration.
The predetermined region Rg can be set by various methods, and may be set to pixels forming a line arranged in the x direction shown in Fig. 3 (15 pixels in Fig. 3), or may be set to pixels forming a line arranged in the y direction shown in Fig. 3 (10 pixels in Fig. 3) In this embodiment, the predetermined region Rg is set to a 5 x 5 region in the x and y directions.
In the embodiment, the predetermined region Rg includes intra-region pixels that are composed of a plurality of pixels. The intra-region pixels include a pixel of interest a1 and peripheral pixels a2 (non-pixels of interest) that are arranged around the pixel of interest a1. The pixel of interest a1 is a reference pixel in the predetermined region Rg, and in the embodiment, is located at the upper left corner of the predetermined region Rg. The peripheral pixels a2 are pixels within a range of 5 pixels in the x direction and 5 pixels in the y direction from the pixel of interest a1.

In a predetermined region Rg of a pixel of interest a1 in a frame F1 shown in Fig. 3, an average value v1 of pixel values is an average value of pixel values in a 5 x 5 range shown in Fig. 4, and is approximately 109. Since the degree of flicker can be judged based on the deviation between the average value v1 and an average value vc described below, the average value v1 has significance as a criterion. For this reason, the average value v1 can also be called a target average value (target average pixel value). In this way, the frame calculation processing unit 1 is configured to obtain the average value v1 as a statistical value (step S2 in Fig. 10: first statistical value obtaining step).
In the predetermined region Rg of the pixel of interest a1 in the frame F2 shown in FIG. 5, the average pixel value v2 is the average pixel value in the 5×5 range shown in FIG.
The average value v1 is an example of a first statistical value.
Thus, although there is almost no change between the average values v1 and v2, there are pixels whose pixel values increase and pixels whose pixel values decrease in the frames shown in Figures 3 and 4. Frames that satisfy such conditions, including frames known as dot mesh images (images in which white pixels and black pixels are arranged alternately), are prone to flicker.

The calculation of the statistical values by the frame calculation processing unit 1 and the calculation of the correction data Ec by the correction data acquisition unit 2 described later are performed sequentially for each predetermined region Rg. For example, as shown in FIG. 3, the calculation of the statistical values, etc. in the 5×5 predetermined region Rg with the coordinates (1,1) as the reference (pixel of interest) is performed in parallel or sequentially with the calculation of the statistical values, etc. in the 5×5 predetermined region Rg with the coordinates (6,1) as the reference (pixel of interest). The same is true for the 5×5 predetermined region Rg with the coordinates (11,1), (1,6), (6,6), and (11,6) as the reference (pixel of interest). In other words, the entire region of the liquid crystal panel 7A is divided into six, and these regions are subject to local dimming control. Note that in the embodiment, the entire region of the liquid crystal panel 7A is described as being subject to local dimming control, but this is not limited to this. For example, any region that is not significantly affected by flicker may be determined in advance, and the region may be excluded from the local dimming control.

2-2 Correction data acquisition unit 2
The correction data acquisition unit 2 has a function of calculating correction data Ec of pixel values. The correction data acquisition unit 2 is configured to perform a correction data acquisition step. The correction data acquisition step includes step S3 (estimated pixel value acquisition step) shown in Fig. 10, step S4 (second statistical value acquisition step) shown in Fig. 10, and step S5 (correction data calculation step) shown in Fig. 10.

As described below, the correction data acquisition unit 2 acquires the liquid crystal response characteristics (liquid crystal response time or liquid crystal response speed) associated with the pixel values of frames F1 and F2 from an LUT (look-up table), and acquires the correction data Ec using this liquid crystal response characteristic. The correction data acquisition unit 2 also acquires the correction data Ec using an estimated pixel value based on this liquid crystal response characteristic. A method for acquiring the correction data Ec will be specifically described below.

The pixel value correction data Ec is a value that indicates the extent to which the pixel value (liquid crystal drive signal Ls of the liquid crystal drive circuit 5) needs to be corrected to reduce flicker, assuming that the setting value of the backlight 7B is not changed when moving from frame F1 to frame F2. In other words, in this embodiment, the pixel value correction data Ec related to the liquid crystal is acquired in advance, and this liquid crystal correction data Ec is converted into a correction amount (backlight correction value) for the backlight 7B described below, to reduce flicker. For this reason, the correction data Ec is the amount of pixel value related to the liquid crystal that corresponds to the correction amount of the backlight 7B setting value.

The correction data Ec of pixel values can be obtained by various methods, but one example will be described here. The occurrence of flicker can be understood as the fluctuation of the average luminance in a predetermined range of the liquid crystal display unit 7 during the transition between previous and next frames. That is, as described above, the average value v1 of the pixel values in the previous frame is 109, and the average value v2 of the pixel values in the next frame is 108, and the two are quite close, but at an intermediate timing (a timing between the previous and next frames), if the average value of the pixel values deviates from the average value v1, flicker occurs. Therefore, in the embodiment, the average value vc of the pixel values at the intermediate timing (an example of the second statistical value) is calculated, and the correction data Ec is calculated using the average value vc.
In the embodiment, the intermediate timing is the middle timing between the timing of the previous frame and the timing of the next frame. In other words, when the timing of the previous frame is 0 and the timing of the next frame is 1, the intermediate timing corresponds to 0.5. Note that the intermediate timing is not limited to being the middle timing between the timing of the previous frame and the timing of the next frame. Specifically, the intermediate timing may correspond to, for example, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, or 0.70, or may be within a range between any two of the numerical values exemplified here.

The memory 4 stores a LUT (lookup table) associated with pixel values of a previous frame (frame F1) and a subsequent frame (frame F2) as shown in FIG. 7. This LUT is configured to estimate (obtain) the liquid crystal response characteristic of an arbitrary coordinate when a pixel value of the previous frame and a pixel value of the arbitrary coordinate of the subsequent frame are determined. In the embodiment, the liquid crystal response characteristic corresponds to a liquid crystal response time from a pixel value of a previous frame to a pixel value of a subsequent frame. In the example shown in FIG. 7, each liquid crystal response characteristic (liquid crystal response time) has a pixel value (tone value) of 32 as one section, but is not limited to this. For example, 1, 2, 4, 8, 16, 32, and 64 can be adopted as the pixel value (tone value) section of the LUT.
As an example, the liquid crystal response characteristics (liquid crystal response time) of a pixel of interest a1 in a predetermined region Rg shown in Figures 3 and 5 will be described. In the previous frame, the pixel value of the pixel of interest a1 is 30 as shown in Figure 4, so section 31 close to the pixel value 30 is referenced. In the subsequent frame, the pixel value of the pixel of interest a1 is 90 as shown in Figure 6, so section 95 close to the pixel value 90 is referenced. As a result, the liquid crystal response characteristics (liquid crystal response time) of this pixel of interest a1 is 33.5 msec.

In this embodiment, it is assumed that the liquid crystal response is linear. In this case, the transition of the pixel of interest a1 can be expressed as a straight line L1 that satisfies the difference D (the difference between pixel value 30 and pixel value 90) and the liquid crystal response characteristic (liquid crystal response time): 33.5 msec, as shown in FIG. 9. The straight line L1 is the transition of the pixel value that is assumed to be real. It can be seen that in this straight line L1, the estimated pixel value predicted at the intermediate timing is 45 (see coordinates (1,1) in FIG. 8). In other words, the correction data acquisition unit 2 can acquire the estimated pixel value based on the difference D and the liquid crystal response characteristic (liquid crystal response time) of the LUT (step S3 in FIG. 10: estimated pixel acquisition step).

By performing such calculations for the pixel at each coordinate, a table can be obtained in which the estimated pixel value for each coordinate is specified, as shown in FIG. 8. From the table in FIG. 8, the average value vc of the pixel values of a predetermined 5×5 region at the intermediate timing can be calculated, which is 97. In other words, the correction data acquisition unit 2 can acquire the average value vc based on the estimated pixel values of the predetermined region Rg (step S4 in FIG. 10: second statistical value acquisition step).

9, T _N corresponds to the timing in the previous frame, T _N+1 corresponds to the timing in the next frame, and T _M corresponds to the intermediate timing. T is the time between the previous and next frames, which is determined in advance and is 16.66 msec in the embodiment. 0.5T is the time from the timing of the previous frame to the intermediate timing, which is half the value of T in the embodiment.

The deviation between the average pixel value v1 and the average pixel value vc corresponds to the magnitude of the flicker. In other words, at the intermediate timing, the average pixel value is expected to drop from 109 to 97, which may cause flicker. In the embodiment, the correction data acquisition unit 2 can calculate the correction data Ec based on the difference between the average pixel value v1 and the average pixel value vc (step S5 in FIG. 10: correction data calculation step). Here, the correction data Ec is 109-97=12.

In the embodiment, the liquid crystal response characteristic stored in the LUT of memory 4 has been described as the liquid crystal response time, but this is not limited to this and may be the liquid crystal response speed. This is because the liquid crystal response speed corresponds to the time required for a transition from one arbitrary pixel value to another arbitrary pixel value, and is therefore essentially the same as the liquid crystal response time.

2-3 Local dimming control unit 3
The local dimming control unit 3 has a backlight correction value calculation function and is configured to acquire a backlight correction value based on the correction data Ec acquired by the correction data acquisition unit 2 (step S6 in FIG. 10: backlight correction value acquisition step).

The backlight correction value calculation function is a function that converts the correction data Ec related to the pixel values (tone values) of the liquid crystal into a backlight correction amount (backlight correction value). As explained above, the correction data Ec is 109-97=12. In other words, when transitioning from frame F1 to frame F2, the average value of the pixel values of a predetermined region Rg may drop from 109 to 97 at an intermediate timing, which may cause flicker. For this reason, the setting value of the backlight 7B is increased by an amount corresponding to the correction data (12), which is the difference in this average value. This increase corresponds to the backlight correction value. Conversely, if the correction data Ec is a negative value, the setting value of the backlight 7B is decreased, and if the correction data Ec is 0, the setting value of the backlight is not changed.

A setting value for driving the backlight 7B can be set in the backlight driving circuit 6. The setting value can be determined by the user or is previously determined in the liquid crystal display device 100. The setting value can be set, for example, between 0 and 1000. When the setting value of the backlight 7B is 0 (minimum value), the luminance of the backlight 7B is 0 cd/ ^m2 , and when the setting value of the backlight 7B is 1000 (maximum value), the luminance of the backlight 7B is 500 cd/ ^m2 . Here, it is assumed that the luminance of the backlight 7B changes linearly from the minimum setting value to the maximum setting value. In other words, when the setting value of the backlight 7B increases by 1, the luminance increases by 0.5 cd/ ^m2 . For example, when the setting value of the backlight 7B is 500, the luminance of the backlight 7B is 250 cd/ ^m2 . Here, for convenience of explanation, it is assumed that the setting value of the backlight 7B is 500.

Here, in order to obtain the backlight correction value Bc, the correction data Ec is converted to luminance (unit: cd/ ^m2 ). The conversion can be calculated using the conversion formula: (luminance of the backlight 7B) × (correction data Ec) ÷ (possible pixel value).
Specifically, the luminance of the backlight 7B is 250 cd/ ^m2 , the correction data Ec is 12, and there are 256 possible pixel values, so the backlight correction value is about 12 cd/ ^m2 . The luminance of the backlight 7B increases by 0.5 cd/ ^m2 every time the set value is increased by one, so the backlight driving circuit 6 drives the backlight 7B so as to increase the set value from 500 to 24 (so as to increase the luminance by 12 cd/ ^m2 ). Note that the calculation here is a rough calculation as an example, but if the luminance setting value of the backlight 7B is in smaller increments, it is possible to reduce flicker more accurately even if the number of significant digits after the decimal point of the backlight correction value increases. In this way, the set value of the backlight 7B is determined to be 524 in a 5×5 predetermined region Rg with the coordinates (1, 1) as the reference (pixel of interest). The above calculation is also carried out for other 5×5 predetermined regions Rg having other coordinates such as (6, 1) as references (pixels of interest), and the setting values are determined in the same manner.

In addition, the period for controlling the backlight 7B using the backlight correction value Bc can be set to be from the timing (T _N ) of the start of frame F1 to the timing (T _{N +1) of displaying the subsequent frame F2, centered around the intermediate timing (T M} ).

2-4 Memory 4, liquid crystal driving circuit 5 and backlight driving circuit 6
The memory 4 stores a LUT (look-up table) shown in FIG.
The liquid crystal drive circuit 5 generates a liquid crystal drive signal Ls for controlling the liquid crystal of the liquid crystal panel 7A for each pixel based on the video signal, and controls the liquid crystal panel 7A.
The backlight drive circuit 6 generates a dimming signal Ds corresponding to the setting value of the backlight 7B based on the backlight correction value Bc, and controls the backlight 7B. The backlight drive circuit 6 is configured to perform synchronous control with the liquid crystal drive circuit 5. In other words, the backlight 7B is controlled by the dimming signal Ds so as to be synchronized with the liquid crystal drive circuit 5 controlling the liquid crystal of the liquid crystal panel 7A to display frames at each timing.

2-5 Liquid crystal display unit 7
The liquid crystal display unit 7 has a liquid crystal panel 7A and a backlight 7B. The LEDs of the backlight 7B are arranged on the rear surface of the liquid crystal panel 7A and are of the direct type. In other words, the backlight 7B is configured to illuminate the liquid crystal panel 7A with light directly from the rear surface side of the liquid crystal panel 7A.
In the embodiment, the backlight 7B is described as being a direct type disposed on the rear surface of the liquid crystal panel 7A, but the present invention is not limited to this, and the backlight 7B may be an edge type. In this case, the backlight 7B may be configured, for example, with edge type LEDs disposed on each of the four sides of the liquid crystal panel 7A. Even if the backlight 7B is an edge type, the light source can be controlled on an area basis.

3. Effects of the embodiment The local dimming control unit 3 of the liquid crystal display device 100 according to the embodiment is configured to acquire a backlight correction value Bc based on correction data Ec for reducing the occurrence of flicker. When the frame displayed on the liquid crystal display unit 7 changes from frame F1 as the previous frame to frame F2 as the next frame, the backlight 7B is driven at a setting value that takes into account the backlight correction value Bc, thereby reducing flicker.

Here, a method of controlling the pixel values themselves (changing the pixel values themselves) can be considered to suppress flicker. In this case, controlling the pixel values means, for example, slowing down the rise and fall of the pixel values of each pixel. This slows down the response characteristics of the liquid crystal, increasing the possibility of causing a phenomenon called "tailing."
Here, the term "tailing" refers to the blurring of an image that occurs when, for example, an object moves in a frame during the process of displaying a number of frames.
The liquid crystal display device 100 of the embodiment is not configured to control the pixel values of the frame themselves (change the pixel values themselves), but is configured to obtain a backlight correction value Bc for controlling the backlight 7B, so that it is possible to avoid affecting the response characteristics of the liquid crystal and to suppress the occurrence of a phenomenon such as "tailing" that changes the appearance of the displayed image.

3 Modification 3-1 Modification 1: Determining whether to correct a predetermined region Rg according to the amount of flicker In the embodiment, the correction data Ec and the backlight correction value Bc for each predetermined region Rg are uniformly acquired, but the present invention is not limited to this. As shown in Fig. 13, the liquid crystal display device 100 may perform a correction determination step S6 described later and determine whether to use the correction data Ec and the backlight correction value Bc according to the degree of flicker occurrence (amount of flicker).
Here, a frame in which flicker is likely to occur will be described.

The predetermined region Rg of the frame F1 in FIGS. 11A to 11C contains many alternating black and white pixels, and can be said to be somewhat close to a dot mesh image.
On the other hand, the predetermined region Rg of frame F2 in Fig. 11A is obtained by shifting the entire predetermined region Rg of frame F1 downward by one position, and the pixel values of the pixels in the top row are 90, 35, 40, 190, and 30. In the case of Fig. 11A, there is a strong tendency for pixels with pixel values closer to white to become pixels with pixel values closer to black, and for pixels with pixel values closer to black to become pixels with pixel values closer to white, so that although the change in the average pixel values of the previous and next frames is small, the difference in liquid crystal response speed is likely to be apparent. In such a situation, the amount of flicker, which will be described later, increases, and flicker is likely to occur.
The predetermined region Rg of frame F2 in Fig. 11B is set so that the change in the average pixel values between the previous and next frames is small, similar to Fig. 11A, but the distribution of pixel values in the predetermined region Rg of frame F2 in Fig. 11B is more random than that of frame F2 in Fig. 11A, making flicker less likely to occur in this situation than in the case of Fig. 11A.
In the predetermined region Rg of frame F2 in FIG. 11C, the average pixel value is significantly greater than the average pixel value of the predetermined region Rg of frame F1, making it less likely for flicker to occur.

Here, the degree of flicker occurrence is defined as the amount of flicker. The amount of flicker corresponds to the degree of flicker occurrence in a predetermined region Rg at the transition from the previous frame to the next frame. The amount of flicker can be expressed as the sum of the differences between a transition line G of the average value of the estimated pixel values at each predetermined timing and a reference line RL, in other words, corresponds to the area formed by the transition line G and the reference line RL.
In this modification, the amount of flicker is the sum of the differences Ar1 to Ar9 shown in Fig. 12A. Comparing the cases of Fig. 11A and Fig. 11B, this sum is larger in Fig. 12A, which corresponds to Fig. 11A, and therefore the degree of flicker occurrence is greater in the case of Fig. 11A. The transition line G of the average value and the like will be described below.

- Each value of the average value transition line G is the same as the average value vc of the estimated pixel values of the 5x5 predetermined area described in the embodiment. The average value vc described in the embodiment was the value at the timing of 0.5T. The average value transition line G of the present modified example is obtained by calculating the average value vc in increments of 0.1T, plotting it, and connecting it with a line. In other words, the time between the previous and next frames (see time T in FIG. 9) is divided into n equal parts (n=10 here), and the average value vc is plotted for each of the n equal parts of time to obtain the transition line G. Note that, as described in the embodiment, assuming that the liquid crystal response is linear, if the difference D between the pixel values of the previous and next frames and the liquid crystal response characteristics (see FIG. 7) are known, the pixel values of each coordinate as shown in FIG. 8 can be estimated in increments of 0.1T, and as a result, the average value vc can be calculated in increments of 0.1T. - The reference line RL is a horizontal line passing through the timing of frame F2 as the subsequent frame. In this modified example, the degree of flicker occurrence is determined by the deviation of the transition line G from this reference line RL. Difference Ar1 is the difference between the value of the transition line G of the average estimated pixel value at the timing of 0.1T and the value of the reference line RL. Similarly, differences Ar2 to Ar9 are the differences between the values of the transition line G of the average estimated pixel value (average estimated pixel value) at the timings of 0.2T to 0.9T and the value of the reference line RL.

Next, a flow of a method for obtaining the backlight correction value Bc in this modified example will be described with reference to FIG.
In step S1 (difference acquisition step), the frame calculation processor 1 acquires the pixel value difference D for each coordinate of the previous and next frames (frames F1, F2) in the same manner as in the embodiment.
In step S2 (first statistical value acquisition step), the frame calculation processing unit 1, as in the embodiment, acquires an average value v1 of estimated pixel values as a statistical value for each predetermined region Rg based on the previous frame (frame F1).

In step S3 (estimated pixel value acquisition step), the correction data acquisition unit 2 acquires estimated pixel values of each pixel at each timing based on the difference D and the LUT (see FIG. 7). That is, in step S3, ten matrices of estimated pixel values as shown in FIG. 8 are generated. Here, the timings refer to 0.1T, 0.2T, 0.3T, 0.4T, 0.5T, 0.6T, 0.7T, 0.8T, 0.9T, and 1.0T.
In this modified example, as in the embodiment, it is assumed that the liquid crystal response is linear. The method of calculating the estimated pixel value at each timing is the same as the method described in FIG. 9 in the embodiment. That is, the section from T _N to T _N+1 shown in FIG. 9 is divided into 10 sections, and the value of the straight line L1 in each divided section is the estimated pixel value at each timing of the pixel at coordinates (1, 1) which is the pixel of interest. In the same manner, the estimated pixel values of the other pixels can also be obtained.

In step S4 (second statistical value acquisition step), the correction data acquisition unit 2 acquires the average value vc of the estimated pixel values for each predetermined region Rg at each timing (0.1T, 0.2T, 0.3T, 0.4T, 0.5T, 0.6T, 0.7T, 0.8T, 0.9T, 1.0T).

In step S5 (flicker amount acquisition step), the correction data acquisition unit 2 acquires the amount of flicker for each predetermined region Rg based on the average value vc of the estimated pixel values at each timing acquired in step S4. The amount of flicker for each predetermined region Rg can be acquired by summing up the differences Ar1 to Ar9, as described above.
In step S6 (correction determination step), the correction data acquisition unit 2 determines a predetermined region Rg for which backlight correction is to be performed based on the amount of flicker acquired in step S5. If the amount of flicker in the predetermined region Rg is equal to or greater than a predetermined threshold, the correction data acquisition unit 2 determines that the predetermined region Rg is a predetermined region Rg for which correction is to be performed. On the other hand, if the amount of flicker in the predetermined region Rg is less than the predetermined threshold, the correction data acquisition unit 2 determines that the predetermined region Rg is a predetermined region Rg for which correction is not to be performed.
For the predetermined region Rg for which it has been determined that correction is to be performed, correction data Ec and a backlight correction value Bc will be obtained in a later step.
On the other hand, for the predetermined region Rg for which it has been determined that no correction is to be performed, the correction data Ec and the backlight correction value Bc are not acquired in the subsequent steps.

In step S7 (correction data calculation step), the correction data acquisition unit 2 calculates correction data Ec for the predetermined region Rg determined to be corrected based on the difference between the average pixel value v1 and the average estimated pixel value vc at the intermediate timing, as in the embodiment. Note that, since the average estimated pixel value vc at 0.5T (intermediate timing) has already been acquired in step S4, the correction data acquisition unit 2 may use this already acquired average value vc.
The correction data acquisition unit 2 does not calculate the correction data Ec for the predetermined region Rg for which it has been determined that no correction is to be performed.

In step S8 (backlight correction value acquisition step), the local dimming control unit 3 acquires the backlight correction value Bc based on the correction data Ec acquired by the correction data acquisition unit 2. Note that the method by which the local dimming control unit 3 converts the correction data Ec into the backlight correction value Bc is the same as in the embodiment.

3-2 Modification 2: Backlight 7B can be controlled for each pixel In the embodiment, the control using the backlight correction value Bc is performed for the entire region of the predetermined region Rg, but the present invention is not limited to this. If the minimum area in which the backlight 7B can be independently controlled is narrower than the predetermined region Rg, the predetermined region Rg can be divided into desired areas narrower than the predetermined region Rg. As an example, the area is described as being for each pixel. In this way, if the minimum area in which the backlight 7B can be independently controlled is narrow, it becomes possible to correct the backlight 7B by targeting pixels in the predetermined region Rg that are likely to be particularly affected by flicker, and the effect of reducing flicker more reliably can be expected. In other words, in the method 1 of this modification 2, when control is performed using the backlight correction value Bc, specific pixels that have a high effect of reducing flicker are extracted.
The configuration of Method 1 of Modification 2 can be implemented in at least two ways, which will be described separately below.

3-2-1 Method 1 of Modification 2: When the backlight correction value Bc differs for each pixel The calculation flow of the backlight correction value Bc in Method 1 of Modification 1 (see FIG. 14) does not have Step S2 in the embodiment (see FIG. 10), and newly includes Step S3 (ideal value acquisition step) and Step S4 (specific pixel extraction step) shown in FIG. 4.

The flow of the method for obtaining the backlight correction value Bc in this modified example will be described with reference to FIG. 14. Note that this modified example will be described assuming that frames F1 and F2 shown in FIG. 15A are used. The pixel values shown in FIG. 15A are the same as the pixel values in FIG. 4 and FIG. 6.

In step S1 (difference acquisition step), the frame calculation processing unit 1 acquires the pixel value difference D for each coordinate of the previous and next frames (frames F1 and F2) in the same manner as in the embodiment. The acquired difference D is as shown in FIG. 15B.

In step S2 (estimated transition amount acquisition step), the correction data acquisition unit 2 acquires an estimated transition amount of each pixel at the intermediate timing based on the difference D and the LUT (see FIG. 7). The estimated transition amount is the difference between the estimated pixel value at the intermediate timing (see FIG. 8) and the pixel value of the previous frame, frame F1. Therefore, the estimated transition amount acquisition step of this step S2 is substantially the same as the estimated pixel value acquisition step described in the embodiment.
It should be noted that the liquid crystal response characteristics (liquid crystal response time) of each pixel shown in Fig. 15C can be obtained by using the LUT shown in Fig. 7. The estimated transition amount of each pixel shown in Fig. 15D can be obtained by using the liquid crystal response characteristics (liquid crystal response time) of each pixel.

The estimated transition amount will be specifically described with reference to FIG. 16. Here, the pixel at coordinates (2, 2) will be described as an example. The straight line L1 shown in FIG. 16 has the same meaning as the straight line L1 shown in FIG. 9 described in the embodiment. The pixel at coordinates (2, 2) changes from a pixel value of 20 to a pixel value of 150. The LUT shown in FIG. 7 shows that the liquid crystal response characteristic at coordinates (2, 2) is 25.4 msec. This shows that the pixel value expected at the intermediate timing for the straight line L1 shown in FIG. 16 is 62.7. Therefore, the estimated transition amount at the intermediate timing for coordinates (2, 2) is 42.7, as shown in FIG. 15D. For other coordinates, the estimated transition amount at the intermediate timing can be obtained by similar calculation.

In step S3 (ideal value acquisition step), the correction data acquisition unit 2 acquires an ideal value of the transition amount. The ideal value of the transition amount is the difference between the pixel value of the previous frame and the pixel value of the intermediate timing when the pixel value of each pixel ideally transitions from the previous frame to the next frame.
It should be noted that by assuming that the ideal transition is a linear transition from the pixel value of the previous frame to the pixel value of the next frame, it is possible to obtain the estimated transition amount for each pixel shown in FIG. 15E.
Specifically, the ideal transition can be represented by a straight line connecting the pixel value of the previous frame and the pixel value of the next frame, as shown by line L2 in Fig. 16. That is, in reality, it takes 25.4 msec for the pixel value to increase from 20 to 150, but ideally, it is desired that the increase takes 16.66 msec. It can be seen from line L2 that the pixel value is 85 at the intermediate timing. Therefore, the ideal value of the transition amount for the pixel at coordinates (2, 2) is 85-20=65. For other coordinates, the ideal value of the transition amount can be obtained by similar calculation.

In step S4 (specific pixel extraction step), the correction data acquisition unit 2 extracts a specific pixel based on the difference between the ideal transition amount (FIG. 15E) and the estimated transition amount of the pixel value (FIG. 15D). Specifically, the correction data acquisition unit 2 extracts a specific pixel based on the insufficient transition amount data shown in FIG. 15F.

The value of the insufficient transition amount data changes depending on whether the absolute value of the liquid crystal response time shown in FIG. 15C is greater than or equal to the time between the previous and next frames (16.66 msec). When the absolute value of the liquid crystal response time is equal to or less than the time, it means that the pixel value transitions to the pixel value of the subsequent frame within the time. In FIG. 15C, pixels whose absolute value of the liquid crystal response time is equal to or less than the time between the previous and next frames (16.66 msec) are highlighted by being surrounded by a dashed circle. Since such pixels are considered not to require correction, the insufficient transition amount data is set to 0. On the other hand, when the absolute value of the liquid crystal response time is greater than the time between the previous and next frames, correction is required. The insufficient transition amount data of such pixels can be obtained based on the difference between the ideal value of the transition amount (FIG. 15E) and the estimated transition amount of the pixel value (FIG. 15D).

Here, the sum of the positive numbers of the deficient transition amount data shown in FIG. 15F is 139.5, and the sum of the negative numbers is 20. The correction data acquisition unit 2 resets the absolute values of the deficient transition amount data with the larger positive and negative sums to 0, starting with the largest absolute value, until the relationship between the magnitudes of these sums is reversed. In other words, in FIG. 15F, since there are more positive sums, the positive numbers are reset to 0, starting with the largest. Specifically, 22.4 at coordinate (4,2), 22.3 at coordinate (2,2), 21 at coordinate (1,3) and coordinate (3,5), and 15.1 at coordinate (1,1) are reset to 0, starting with the largest. At this time, the sum of the remaining positive numbers is 21.9. Next, if 11.5 at coordinate (3,2) is reset to 0, the sum of the positive numbers and the sum of the negative numbers will be reversed. Therefore, the correction data acquisition unit 2 stops the calculation of setting the insufficient transition amount data to 0, and extracts the coordinates related to the calculation before the magnitude relationship between the positive sum and the negative sum is reversed as specific pixels. In this explanation, the specific pixels are coordinates (4, 2), (2, 2), (1, 3), (3, 5), and (1, 1). Note that in FIG. 15F, the specific pixels are highlighted by being surrounded by dashed circles, and pixels whose value will reverse the magnitude relationship between the positive sum and the negative sum by setting them to 0 are highlighted by being surrounded by dashed squares.

In this way, the correction data acquisition unit 2 resets the missing transition amount data of the larger sign of the positive sum or the negative sum to zero, starting from the larger missing transition amount data of the larger sign, for the missing transition amount data based on the difference between the ideal value of the transition amount and the estimated transition amount of the pixel value, until the positive sum and the negative sum are reversed.The correction data acquisition unit 2 then extracts the pixel at the coordinates that have been reset to zero as the specific pixel.

In step S5 (correction data calculation step), the correction data acquisition unit 2 calculates correction data Ec for each pixel extracted as a specific pixel. As the correction data Ec, the missing transition amount data shown in FIG. 15F can be used. For example, for coordinates (1, 4), the correction data Ec is 7. Note that the correction data acquisition unit 2 does not acquire correction data Ec for pixels in the predetermined region Rg that were not extracted as specific pixels.

In step S6 (backlight correction value acquisition step), the local dimming control unit 3 acquires the backlight correction value Bc of each specific pixel based on the correction data Ec of each specific pixel. Note that the method by which the local dimming control unit 3 converts the correction data Ec of the specific pixel into the backlight correction value Bc is the same as in the embodiment.

In method 1 of this modified example 2, a form in which specific pixels are extracted for each predetermined region Rg has been described, but this is not limited to this, and specific pixels may be extracted directly from the entire liquid crystal panel 7A.

In method 1 of this modified example 2, the intermediate timing is set to 0.5T, but this is not limited to this and may be other timings as explained in the embodiment.

3-2-2 Method 2 of Modification 2: When the backlight correction value Bc is common In the above 3-2-1, specific pixels are extracted and correction data Ec is obtained for each specific pixel, but common correction data Ec can also be used for the specific pixels. Note that the common correction data Ec may be, for example, an average value or a median value of the insufficient transition amount data of the specific pixels, or a histogram.
The operation of method 2 in this modified example 2 is basically the same as that of method 1 in the flowchart of Figure 14, except that in step S5, correction data Ec common to specific pixels is obtained, and in step S6, a common backlight correction value Bc is obtained based on the common correction data Ec.

Method 1 or 2 of Modification 2 may be combined with, for example, the configuration of Modification 1. In other words, a predetermined region Rg to be corrected may be determined by Modification 1, and specific pixels may be extracted from the determined predetermined region.

3-3 Modification 3: Regarding statistical values In the embodiment, various calculations are performed using the average value v1 and the average value v2 (an example of the first statistical value) and the average value vc (an example of the second statistical value), but this is not limiting. In addition to the average value, a median value or a histogram may be used.

3-4 Modification 4: Method of Acquiring Liquid Crystal Response Characteristics In the embodiment, the method of acquiring an estimated pixel value using the liquid crystal response characteristics stored in the LUT has been described, but the present invention is not limited to this. The liquid crystal response characteristics may be calculated each time using an arithmetic expression that can acquire the liquid crystal response characteristics based on the pixel values of the previous and next frames.

3-5 Modification 5: Regarding Light Source Control In the embodiment, the backlight correction value Bc is obtained after performing local dimming control as an example of light source control, but the present invention is not limited to this, and the light source control does not have to be local dimming control. Specifically, in the embodiment, various values are calculated for each area (each predetermined region Rg) and the backlight is controlled, but in the present modification 5, various values are calculated in a state where the entire backlight 7B is grouped together and the backlight is controlled. In other words, the configuration of modification 5 corresponds to expanding the predetermined region Rg described in the embodiment to the entire region of the liquid crystal panel 7A (the entire 15×10 region in the frame of FIG. 3 or FIG. 5).

In the fifth modification, as shown in FIG. 17, the liquid crystal display device 100 includes a light source control unit 3t instead of the local dimming control unit 3 shown in FIG. 2 of the embodiment.

In this modification 5, the difference calculation function of the frame calculation processor 1 is the same as that of the embodiment. Also, the statistical value calculation function of the frame calculation processor 1 is applied to the entire 15×10 region shown in Fig. 3 and Fig. 5. The calculation method of the average value v1 and the average value v2 is the same as that of the embodiment.
In the present modified example 5, the method of calculating the average value vc in the correction data acquisition unit 2 is the same as that in the embodiment. That is, the correction data acquisition unit 2 calculates the average value vc of pixel values of the entire 15×10 region at the intermediate timing using a table in which estimated pixel values of each coordinate are specified, as shown in Fig. 8. Then, the correction data acquisition unit 2 can acquire correction data Ec based on the difference between the average value v1 and the average value vc.
In the present modified example 5, the method of acquiring the backlight correction value Bc of the light source control unit is the same as that of the embodiment. That is, the light source control unit can acquire the backlight correction value Bc to be applied to the entire 15×10 region based on the correction data Ec acquired by the correction data acquisition unit 2.

Modification 5 can also be combined with Modification 1. That is, the liquid crystal display device 100 according to Modification 5 may have a configuration for determining, in accordance with the amount of flicker, whether or not to perform backlight correction for the entire 15×10 region.
Furthermore, Modification 5 can be combined with Method 1 and Method 2 of Modification 2. That is, the liquid crystal display device 100 according to Modification 5 may obtain the backlight correction value Bc for each pixel in the entire 15×10 region.
Furthermore, this modified example 5 can be combined with modified example 1 and method 1 or method 2 of modified example 2.

1: Frame calculation processing unit 2: Correction data acquisition unit 3: Local dimming control unit (light source control unit)
3t: Light source control unit 4: Memory 5: Liquid crystal drive circuit 6: Backlight drive circuit 7: Liquid crystal display unit 7A: Liquid crystal panel 7B: Backlight 100: Liquid crystal display device 200: Output device

Claims (12)

1. In a liquid crystal display device that controls a backlight as a light source,
   the liquid crystal display device is configured to reduce flicker caused by a difference in liquid crystal response speed between a pixel whose pixel value increases and a pixel whose pixel value decreases during a transition from a first frame to a second frame;
   A correction data acquisition unit and a light source control unit are provided,
   the correction data acquisition unit is configured to acquire correction data for reducing the occurrence of flicker based on pixel values of first and second frames;
   the light source control unit is configured to obtain a backlight correction value based on the correction data;
   The backlight correction value is used for the light source control of the backlight during a predetermined period between a first frame and a second frame.
2. The liquid crystal display device according to claim 1 ,
   the correction data acquisition unit acquires the correction data using a liquid crystal response characteristic in which a pixel value of a first frame and a pixel value of a second frame are associated with each other;
   The liquid crystal response characteristic is a liquid crystal response speed or a liquid crystal response time.
3. The liquid crystal display device according to claim 2,
   the correction data acquisition unit acquires the correction data by using an estimated pixel value based on the liquid crystal response characteristic;
   the estimated pixel value is a pixel value at an intermediate timing,
   The intermediate timing is a timing between the first and second frames.
4. The liquid crystal display device according to any one of claims 1 to 3,
   the light source control unit is configured to obtain the backlight correction value to be applied to pixels in the region based on the correction data of the pixels in the region;
   A liquid crystal display device, wherein the intra-region pixels are composed of a plurality of pixels included in a predetermined region of the first and second frames.
5. The liquid crystal display device according to claim 4,
   the correction data acquisition unit is configured to acquire the correction data based on a difference between first and second statistical values;
   the first statistical value is a statistical value based on pixel values of the plurality of pixels within the region of the first frame;
   the second statistical value is a statistical value based on pixel values of the pixels in the region at an intermediate timing;
   The intermediate timing is a timing between the first and second frames.
6. The liquid crystal display device according to claim 5 ,
   A liquid crystal display device, wherein the statistical value is an average value, a median value, or a value obtained based on a histogram.
7. The liquid crystal display device according to claim 4,
   the correction data acquisition unit is configured to extract a specific pixel from among pixels within the region, and to acquire the correction data for the extracted specific pixel;
   The liquid crystal display device, wherein the light source control unit is configured to obtain the backlight correction value based on the correction data of the specific pixel.
8. The liquid crystal display device according to claim 4,
   the correction data acquisition unit is configured to acquire an amount of flicker for each of the predetermined regions, and is configured to determine whether or not to use the correction data and the backlight correction value for the predetermined regions based on the amount of flicker;
   A liquid crystal display device, wherein the amount of flicker corresponds to a degree to which the flicker occurs in the predetermined region during a transition from a first frame to a second frame.
9. A liquid crystal display device according to any one of claims 1 to 8,
   The first and second frames are dot mesh images.
10. A liquid crystal display device according to any one of claims 1 to 9,
    the light source control is a local dimming control,
    The backlight correction value is used for the local dimming control of the backlight corresponding to at least pixels including a pixel of interest during a predetermined period between first and second frames.
11. In a liquid crystal display method for controlling a backlight as a light source,
    The liquid crystal display method includes reducing flicker caused by a difference in liquid crystal response speed between pixels whose pixel values increase and pixels whose pixel values decrease during a transition from a first frame to a second frame;
    The method includes a correction data acquisition step and a backlight correction value acquisition step,
    In the correction data acquisition step, correction data for reducing the occurrence of the flicker is acquired based on pixel values of the first and second frames;
    In the backlight correction value acquisition step, a backlight correction value is acquired based on the correction data,
    The method of claim 1, wherein the backlight compensation value is used in the light source control of the backlight during a predetermined period between a first and a second frame.
12. A program that causes a computer to execute the liquid crystal display method described in claim 11.

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