Image display device and image display method

Abstract

The present invention provides an image display device and an image display method that can improve the contrast of the displayed image and reduce brightness unevenness. [Solution] The image display device 100 includes the steps of: creating brightness setting data D1 using an input image IM input to a controller 150 of a backlight 110 having a plurality of light-emitting regions 110s and a liquid crystal panel 130 having a plurality of pixels 130p; creating brightness estimation data D2 based on the brightness setting data and the brightness profile D4 of each light source 114 arranged in each light-emitting region; calculating the maximum brightness e2max of the brightness estimation data; creating gradation setting data D3 by correcting the gradation of each pixel IMp of the input image using formula (1) based on the brightness estimation data and the maximum brightness; and displaying an image on the liquid crystal panel by controlling the backlight based on the brightness setting data and controlling the liquid crystal panel based on the gradation setting data.

Description

Technical Field

[0001] Embodiments relate to an image display device and an image display method.

Background Art

[0002] Conventionally, an image display device including a backlight having a plurality of light-emitting regions arranged in a matrix and a light source disposed in each light-emitting region, and a liquid crystal panel disposed above the backlight and having a plurality of pixels is known. By using such an image display device, the luminance of each light-emitting region can be individually set according to an image to be displayed on the liquid crystal panel, and the gradation of each pixel of the liquid crystal panel can be set according to the luminance of each light-emitting region. Thereby, the contrast of the image displayed on the liquid crystal panel can be improved. Such a technique is called "local dimming".

[0003] As a method of setting the gradation of each pixel of the liquid crystal panel in local dimming, the luminance directly below each pixel of the liquid crystal panel is estimated based on the set value of the luminance of each light-emitting region of the backlight, and the gradation of each pixel of the image to be displayed is corrected based on the estimated direct-below luminance, and the set value of the gradation of each pixel of the liquid crystal panel is used. At this time, there is a desire to set the gradation of each pixel of the liquid crystal panel so that the contrast of the image displayed on the liquid crystal panel is improved.

[0004] When setting the gradation of each pixel of the liquid crystal panel, it is conceivable to calculate the gradation based on the luminance estimation data and the maximum luminance. However, since there are differences in positions that tend to become bright and positions that tend to become dark for each liquid crystal panel, luminance unevenness may occur depending on the liquid crystal panel.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

[0006] The embodiment aims to provide an image display device and an image display method that can improve the contrast of the displayed image and reduce brightness unevenness. [Means for solving the problem]

[0007] An image display device according to one embodiment includes a backlight having a planar light source having a plurality of light-emitting regions arranged in a matrix, with a light source placed in each of the plurality of light-emitting regions; a liquid crystal panel located on the backlight and having a plurality of pixels; and a controller for controlling the backlight and the liquid crystal panel. The controller includes a brightness setting data creation unit that creates brightness setting data defining a set value for the brightness of each of the light-emitting regions of the backlight using an input image; a brightness estimation data creation unit that creates brightness estimation data estimating the brightness directly below each pixel of the liquid crystal panel based on the brightness setting data and the brightness profile of each of the light sources; a maximum brightness calculation unit that calculates the maximum brightness of the brightness estimation data; a gradation setting data creation unit that creates gradation setting data defining a set value for the gradation of each pixel of the liquid crystal panel by correcting the gradation of each pixel of the input image using the following formula (1) based on the brightness estimation data and the maximum brightness; and a control unit that controls the backlight based on the brightness setting data, controls the liquid crystal panel based on the gradation setting data, and displays an image on the liquid crystal panel.

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[0008] An image display device according to another embodiment includes a backlight having a planar light source having a plurality of light-emitting regions arranged in a matrix, with a light source placed in each of the plurality of light-emitting regions; a liquid crystal panel located on the backlight and having a plurality of pixels; and a controller for controlling the backlight and the liquid crystal panel. The controller includes: a brightness setting data creation unit that creates brightness setting data that defines brightness setting values ​​for each of the light-emitting regions of the backlight using an input image; a brightness estimation data creation unit that creates brightness estimation data that estimates the brightness directly below each of the pixels of the liquid crystal panel based on the brightness setting data and the brightness profile of each of the light sources; a maximum brightness calculation unit that calculates the maximum brightness for each area corresponding to one or more of the light-emitting regions in the brightness estimation data; a gradation setting data creation unit that creates gradation setting data that defines gradation setting values ​​for each of the pixels of the liquid crystal panel by correcting the gradation of each pixel of the input image using the following formula (2) based on the brightness estimation data and the maximum brightness of the area to which each of the pixels belongs among the plurality of areas; and a control unit that controls the backlight based on the brightness setting data, controls the liquid crystal panel based on the gradation setting data, and displays an image on the liquid crystal panel.

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[0009] An image display method according to one embodiment includes the steps of: creating brightness setting data that defines a set value for the brightness of each light-emitting region of a backlight, using an input image input to a controller of a backlight having a plurality of light-emitting regions arranged in a matrix and a liquid crystal panel having a plurality of pixels; creating brightness estimation data that estimates the brightness directly below each pixel of the liquid crystal panel based on the brightness setting data and the brightness profiles of each light source arranged in each of the light-emitting regions of the backlight; calculating the maximum brightness of the brightness estimation data; creating gradation setting data that defines a set value for the gradation of each pixel of the liquid crystal panel by correcting the gradation of each pixel of the input image using the following formula (1) based on the brightness estimation data and the maximum brightness; and controlling the backlight based on the brightness setting data, controlling the liquid crystal panel based on the gradation setting data, and displaying an image on the liquid crystal panel.

number

[0010] Another embodiment of the image display method includes the steps of: creating brightness setting data that defines a brightness setting value for each light-emitting region of a backlight and a liquid crystal panel having multiple pixels, using an input image input to a controller of a backlight having multiple light-emitting regions arranged in a matrix; creating brightness estimation data that estimates the brightness directly below each pixel of the liquid crystal panel based on the brightness setting data and the brightness profiles of each light source provided in each of the light-emitting regions of the backlight; calculating the maximum brightness of each area corresponding to one or more of the light-emitting regions in the brightness estimation data; creating gradation setting data that defines a gradation setting value for each pixel of the liquid crystal panel by correcting the gradation of each pixel of the input image using the following formula (2) based on the brightness estimation data and the maximum brightness of the area to which each pixel belongs among the multiple areas; and controlling the backlight based on the brightness setting data and controlling the liquid crystal panel based on the gradation setting data to display an image.

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[0011] According to the embodiment, an image display device and an image display method can be provided that can improve the contrast of the displayed image and reduce brightness unevenness. [Brief explanation of the drawing]

[0012] [Figure 1] This is an exploded perspective view showing an image display device according to the first embodiment. [Figure 2]It is a top view showing a planar light source in a backlight of an image display device according to the first embodiment. [Figure 3] It is a cross-sectional view taken along line III-III of FIG. 2. [Figure 4] It is a top view showing a liquid crystal panel of an image display device according to the first embodiment. [Figure 5] It is a block diagram showing an image display device according to the first embodiment. [Figure 6] It is a flowchart showing an image display method according to the first embodiment. [Figure 7] In the image display device according to the first embodiment, it is a schematic diagram showing an input image input to a controller. [Figure 8] In the image display device according to the first embodiment, it is a schematic diagram showing the relationship between pixels of an input image input to a controller, light emission regions of a backlight, and pixels of a liquid crystal panel. [Figure 9] It is a schematic diagram showing a method for creating luminance setting data in the image display method according to the first embodiment. [Figure 10] In the backlight of the image display device according to the first embodiment, it is a graph showing a luminance profile when a light source in one light emission region is lit. [Figure 11] It is a schematic diagram showing a method for creating luminance estimation data in the image display method according to the first embodiment. [Figure 12] In the image display method according to the first embodiment, it is a schematic diagram showing a method for calculating the maximum luminance. [Figure 13] In the image display method according to the first embodiment, it is a schematic diagram showing a method for creating gradation setting data. [Figure 14A] It is a graph showing the relationship between normalized luminance and gradation, showing the case where the maximum value of the normalized luminance is 1. [Figure 14B] It is a graph showing the relationship between normalized luminance and gradation, showing the case where the maximum value of the normalized luminance is less than 1. [Figure 14C]This graph shows the relationship between normalized luminance and grayscale, specifically the case where the maximum value of normalized luminance exceeds 1. [Figure 15] This graph schematically illustrates the correction of tonal gradation. [Figure 16] This is a schematic diagram showing the method for calculating the maximum brightness in the image display method according to the second embodiment. [Figure 17] This is a schematic diagram showing a method for creating grayscale setting data in the image display method according to the second embodiment. [Figure 18A] This is a schematic diagram illustrating another example of an area in luminance estimation data. [Figure 18B] This is a schematic diagram illustrating another example of an area in luminance estimation data. [Figure 18C] This is a schematic diagram illustrating another example of an area in luminance estimation data. [Figure 19A] This is a schematic diagram showing the brightness distribution of a reference example LCD panel. [Figure 19B] This is a schematic diagram showing the brightness distribution of the liquid crystal panel in the embodiment. [Figure 19C] This table shows the brightness of the liquid crystal panel in the reference example and the liquid crystal panel in the embodiment. [Modes for carrying out the invention]

[0013] The embodiments will be described below with reference to the drawings. Note that the drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the ratio of the sizes of the parts, etc., are not necessarily the same as those of actual objects. Furthermore, even when representing the same part, the dimensions and ratios may be shown differently in different drawings. In addition, in this specification and in each drawing, elements similar to those described in previously shown drawings are denoted by the same reference numerals, and detailed explanations are omitted where appropriate.

[0014] Furthermore, in order to make the explanation easier to understand, the arrangement and configuration of each part of the image display device will be described using the XYZ Cartesian coordinate system. The X, Y, and Z axes are mutually orthogonal. The direction in which the X axis extends will be referred to as the "X direction," the direction in which the Y axis extends as the "Y direction," and the direction in which the Z axis extends as the "Z direction." Also, in order to make the explanation easier to understand, the Z direction will be considered upward and the opposite direction downward, but these directions are unrelated to the direction of gravity. Also, in order to make the explanation easier to understand, in each diagram, the direction of the arrow in which the X axis extends will be referred to as the "+X direction," and the opposite direction will be referred to as the "-X direction." Similarly, the direction of the arrow in which the Y axis extends will be referred to as the "+Y direction," and the opposite direction will be referred to as the "-Y direction."

[0015] <First Embodiment> First, let me describe the first embodiment. Figure 1 is an exploded perspective view showing the image display device according to this embodiment. The image display device 100 according to this embodiment is a liquid crystal module (LCM) used in the display of devices such as televisions, personal computers, or game consoles. The image display device 100 comprises a backlight 110, a driver 120 for the backlight, a liquid crystal panel 130, a driver 140 for the liquid crystal panel, and a controller 150. The parts of the image display device 100 will be described below. In Figure 1, for the sake of clarity, the electrical connections between components are shown by connecting them with solid lines.

[0016] The backlight 110 is driveable by local dimming. The backlight 110 includes a planar light source 111 and an optical element 118 disposed on the planar light source 111.

[0017] The optical element 118 is not particularly limited, but for example, it may be a sheet, film, or plate having a light adjustment function such as a light diffusion function. In this embodiment, the number of optical elements 118 provided in the backlight 110 is one. However, the number of optical elements provided in the backlight may be two or more.

[0018] Figure 2 is a top view showing a planar light source in the backlight of the image display device according to this embodiment. Figure 3 is a cross-sectional view taken along the line III-III in Figure 2. In this embodiment, the planar light source 111 includes a substrate 112, a light-reflective sheet 112s, a light guide member 113, a plurality of light sources 114, a light-transmitting member 115, a first light-adjusting member 116, and a light-reflecting member 117, as shown in Figures 2 and 3.

[0019] The substrate 112 is a wiring board having an insulating member and a plurality of wirings provided on the insulating member. In this embodiment, the shape of the substrate 112 in a top view is substantially rectangular, as shown in Figure 2. However, the shape of the substrate is not limited to the above shape. The top and bottom surfaces of the substrate 112 are flat surfaces and are generally parallel to the X and Y directions.

[0020] As shown in Figure 3, the light-reflective sheet 112s is placed on the substrate 112. In this embodiment, the light-reflective sheet 112s has a first adhesive layer, a light-reflective layer provided on the first adhesive layer, and a second adhesive layer provided on the light-reflective layer. The light-reflective sheet 112s is attached to the substrate 112 by the first adhesive layer.

[0021] The light guide member 113 is placed on the light-reflective sheet 112s. At least a portion of the lower surface of the light guide member 113 is attached to the light-reflective sheet 112s by a second adhesive layer. In this embodiment, the shape of the light guide member 113 is plate-like. The thickness of the light guide member 113 is preferably, for example, 200 μm or more and 800 μm or less. The light guide member 113 may be composed of a single layer or a laminate of multiple layers in the thickness direction. In this embodiment, the shape of the light guide member 113 when viewed from above is substantially rectangular, as shown in Figure 2. However, the shape of the light guide member is not limited to the shape described above.

[0022] Materials used for such light guide members 113 include, for example, thermoplastic resins such as acrylic, polycarbonate, cyclic polyolefin, polyethylene terephthalate, or polyester; thermosetting resins such as epoxy or silicone; or glass.

[0023] The light guide member 113 has a plurality of light source placement sections 113a. The plurality of light source placement sections 113a are arranged in a matrix when viewed from above. In this embodiment, each light source placement section 113a is a through hole that penetrates the light guide member 113 in the Z direction, as shown in Figure 3. However, the light source placement section may be a bottomed recess provided on the lower surface of the light guide member.

[0024] Each light source 114 is located within each light source arrangement section 113a. Therefore, multiple light sources 114 are also arranged in a matrix, as shown in Figure 2. However, a light guide member is not necessarily required for a planar light source. For example, a planar light source may not have a light guide member and may simply consist of multiple light sources arranged in a matrix on a substrate. Note that when a light guide member is not present, the light source arrangement section refers to the part of the substrate where the light sources are located.

[0025] Each light source 114 may be a light-emitting element alone, or it may have a light-emitting device that combines a light-emitting element with, for example, a wavelength conversion member. In this embodiment, as shown in Figure 3, each light source 114 includes a light-emitting element 114a and a wavelength conversion member 114b, as well as a second light adjustment member 114h and a third light adjustment member 114i.

[0026] The light-emitting element 114a is, for example, an LED (Light Emitting Diode) and includes a semiconductor laminate 114c and a pair of electrodes 114d and 114e that electrically connect the semiconductor laminate 114c to the wiring of the substrate 112. In the light-reflective sheet 112s, through holes are provided in the portions located directly beneath each electrode 114d and 114e. Conductive members 112m are arranged within these through holes to electrically connect each electrode 114d and 114e to the substrate 112.

[0027] The wavelength conversion member 114b includes a light-transmitting member 114f that covers the top and side surfaces of the semiconductor laminate 114c, and a wavelength conversion material 114g disposed within the light-transmitting member 114f that converts the wavelength of light emitted by the semiconductor laminate 114c to a different wavelength. The wavelength conversion material 114g is, for example, a phosphor.

[0028] In this embodiment, the light-emitting element 114a emits blue light. On the other hand, the wavelength conversion member 114b emits red light from a phosphor (hereinafter referred to as a red phosphor), such as a CASN-type phosphor (e.g., CaAlSiN3:Eu), a KSF-type phosphor (e.g., K2SiF6:Mn), or a KSAF-type phosphor (e.g., K2(Si,Al)F6:Mn), and a phosphor having a perovskite structure (e.g., CsPb(F,Cl,Br,I)3), a β-sialon-type phosphor (e.g., (Si,Al)3(O,N)4:Eu), or a LAG-type phosphor (e.g., Lu3(Al,Ga)5O 12 The backlight 110 includes a phosphor that emits green light, such as :Ce (hereinafter referred to as "green phosphor"). As a result, the backlight 110 can emit white light, which is a mixture of blue light emitted by the light-emitting element 114a and red and green light emitted by the wavelength conversion member 114b. Alternatively, the wavelength conversion member 114b may be replaced with a translucent member that does not contain a phosphor. In this case, for example, a phosphor sheet containing a red phosphor and a green phosphor can be placed on a planar light source to obtain similar white light.

[0029] The second light adjusting member 114h is positioned on the upper surface of the wavelength conversion member 114b and can control the amount and direction of light emitted from the upper surface of the wavelength conversion member 114b. The third light adjusting member 114i is positioned on the lower surface of the light-emitting element 114a and the lower surface of the wavelength conversion member 114b so that the lower surfaces of electrodes 114d and 114e are exposed. The third light adjusting member 114i can reflect light directed toward the lower surface of the wavelength conversion member 114b and control it so that it is emitted from the upper surface and sides of the wavelength conversion member 114b. The second light adjusting member 114h and the third light adjusting member 114i can each be composed of a light-transmitting resin and a light-diffusing agent contained in the light-transmitting resin. The light-transmitting resin can be, for example, a silicone resin, epoxy resin, or acrylic resin. Examples of light diffusing agents include particles such as TiO2, SiO2, Nb2O5, BaTiO3, Ta2O5, Zr2O3, Y2O3, Al2O3, ZnO, MgO, BaSO4, or glass. Furthermore, the second light adjustment member 114h may be made of a metal such as Al or Ag to prevent the brightness directly above the light source 114 from becoming too high.

[0030] A light-transmitting member 115 is placed within the light source arrangement section 113a. The light-transmitting member 115 covers the light source 114. A first light-adjusting member 116 is placed on the light-transmitting member 115. The first light-adjusting member 116 can reflect some of the light incident from the light-transmitting member 115 and transmit other parts so that the brightness directly above the light source 114 does not become too high. The same material as the second light-adjusting member 114h or the third light-adjusting member 114i can be used for such a first light-adjusting member 116.

[0031] Furthermore, the light guide member 113 is provided with partition grooves 113b that surround each light source arrangement section 113a when viewed from above. The partition grooves 113b extend in a grid pattern in the X and Y directions. The partition grooves 113b penetrate the light guide member 113 in the Z direction. However, the partition grooves may be recesses provided on the upper or lower surface of the light guide member. Also, the partition grooves do not have to be provided on the light guide member.

[0032] A light-reflecting member 117 is placed within the partition groove 113b. For example, a translucent resin containing a light-diffusing agent can be used as the light-reflecting member 117. Examples of light-diffusing agents include particles such as TiO2, SiO2, Nb2O5, BaTiO3, Ta2O5, Zr2O3, ZnO, Y2O3, Al2O3, MgO, BaSO4, or glass. Examples of translucent resins include silicone resin, epoxy resin, or acrylic resin. Alternatively, a metal member such as Al or Ag may be used as the light-reflecting member 117. The light-reflecting member 117 covers a portion of the side surface of the partition groove 113b in a layered manner. However, the light-reflecting member may be arranged to fill the entire partition groove. Furthermore, the light-reflecting member does not necessarily have to be placed within the partition groove.

[0033] In this embodiment, the outputs of the multiple light sources 114 can be individually controlled by the backlight driver 120. Here, "controllable output" means that it is possible to switch between turning the lights on and off, and that the brightness in the lit state can be adjusted. For example, the planar light source may have a structure in which the output can be controlled for each light source, or multiple light source groups may be arranged in a matrix and the output can be controlled for each light source group.

[0034] In this specification, when a planar light source is divided into regions containing individually controlled light sources or groups of light sources in a top view, each region is referred to as a "light-emitting region." In other words, a light-emitting region means the smallest region in the backlight where brightness is controlled by local dimming. Therefore, in this embodiment, similar to the partition groove 113b, each region when the planar light source 111 is divided into a grid corresponds to a light-emitting region 110s.

[0035] Each light-emitting region 110s has a rectangular shape. In this embodiment, one light source 114 is provided within each light-emitting region 110s. The backlight driver 120 individually controls the output of multiple light sources 114, thereby individually controlling the brightness of multiple light-emitting regions 110s. As mentioned above, when the output is controlled for each group of light sources, one group of light sources, i.e., multiple light sources, is arranged within a single light-emitting region, and the multiple light sources are turned on or off simultaneously.

[0036] The multiple light-emitting regions 110s are arranged in a matrix when viewed from above. In the following, in a matrix structure such as multiple light-emitting regions 110s, the group of elements of the matrix, such as the light-emitting regions 110s, arranged in the X direction will be called a "row," and the group of elements of the matrix, such as the light-emitting regions 110s, arranged in the Y direction will be called a "column." For example, as shown in Figure 2, the row located furthest to the +Y direction (the leftmost row) will be called the "first row," and the row located furthest to the -Y direction (the rightmost row) will be called the "last row." Similarly, as shown in Figure 2, the column located furthest to the -X direction (the bottommost column) will be called the "first column," and the column located furthest to the +X direction (the topmost column) will be called the "last column." The multiple light-emitting regions 110s are arranged to form N1 rows and M1 columns. Here, N1 and M1 are arbitrary integers, and Figure 2 shows an example where N1 is 8 and M1 is 16.

[0037] As shown in Figure 3, the planar light source 111 is provided with partition grooves 113b and light-reflecting members 117, but the space between adjacent light-emitting regions 110s is not completely shielded from light. Therefore, light can propagate between adjacent light-emitting regions 110s. Consequently, when a light source 114 within one light-emitting region 110s is turned on, the light emitted by this light source can propagate to the surrounding light-emitting regions 110s.

[0038] As shown in Figure 1, the backlight driver 120 is connected to the circuit board 112 and the controller 150. The backlight driver 120 includes drive circuits for multiple light sources 114. The backlight driver 120 adjusts the brightness of each light-emitting area 110s according to the backlight control data SG1 received from the controller 150.

[0039] Figure 4 is a top view showing the liquid crystal panel of the image display device according to this embodiment. A liquid crystal panel 130 is positioned on the backlight 110. In this embodiment, the shape of the liquid crystal panel 130 when viewed from above is approximately rectangular. The liquid crystal panel 130 has multiple pixels 130p arranged in a matrix. In Figure 4, one region enclosed by a dashed line corresponds to one pixel 130p.

[0040] The liquid crystal panel 130 according to this embodiment is capable of displaying color images. Therefore, one pixel 130p includes three subpixels 130sp, for example, a subpixel that can transmit blue light, a subpixel that can transmit green light, and a subpixel that can transmit red light from the white light emitted from the backlight 110. The light transmittance of each subpixel 130sp can be individually controlled by the liquid crystal panel driver 140. This allows for individual control of the gradation of each subpixel 130sp.

[0041] Multiple pixels 130p are arranged to form N2 rows and M2 columns, where N2 and M2 are arbitrary integers, N2 > N1 and M2 > M1. In a top view, multiple pixels 130p are arranged within each light-emitting region 110s. In Figure 4, an example is shown where four pixels 130p correspond to one light-emitting region 110s, but the number of pixels 130p corresponding to one light-emitting region 110s may be three or less, or five or more.

[0042] As shown in Figure 1, the LCD panel driver 140 is connected to the LCD panel 130 and the controller 150. The LCD panel driver 140 includes a drive circuit for the LCD panel 130. The LCD panel driver 140 adjusts the gradation of each pixel 130p according to the LCD panel control data SG2 received from the controller 150.

[0043] Figure 5 is a block diagram of the image display device according to this embodiment. In this embodiment, the controller 150 includes an input interface 151, a memory 152, a processor 153 such as a CPU (central processing unit), and an output interface 154. These are interconnected by a bus.

[0044] The input interface 151 is connected to an external device 900, such as a tuner, personal computer, or game console. The input interface 151 includes a connection terminal to the external device 900, such as an HDMI® (High-Definition Multimedia Interface) terminal. The external device 900 inputs an input image IM to the controller 150 via the input interface 151.

[0045] Memory 152 includes, for example, ROM (Read-Only Memory) and RAM (Random-Access Memory). Memory 152 stores various programs, parameters, and data for displaying images on the liquid crystal panel.

[0046] The processor 153 processes the input image IM by reading a program stored in the memory 152, determines the brightness setting value for each light-emitting area 110s of the backlight 110 and the gradation setting value for each pixel 130p of the liquid crystal panel 130, and controls the backlight 110 and the liquid crystal panel 130 based on these setting values. As a result, the image corresponding to the input image IM is displayed on the liquid crystal panel 130. The processor 153 includes a brightness setting data creation unit 153a, a brightness estimation data creation unit 153b, a maximum brightness calculation unit 153c, a gradation setting data creation unit 153d, and a control unit 153e.

[0047] The output interface 154 is connected to the backlight driver 120. The output interface 154 also includes a connection terminal for the LCD panel driver 140, such as an HDMI® terminal, and is connected to the LCD panel driver 140. The backlight driver 120 obtains backlight control data SG1 via the output interface 154. The LCD driver 140 obtains LCD panel control data SG2 via the output interface 154.

[0048] The following describes an image display method using the image display device 100 according to this embodiment. The functions of the processor 153 as a brightness setting data creation unit 153a, a brightness estimation data creation unit 153b, a maximum brightness calculation unit 153c, a grayscale setting data creation unit 153d, and a control unit 153e will also be described.

[0049] Figure 6 is a flowchart showing the image display method according to this embodiment. The image display method according to this embodiment comprises an input image IM acquisition step S1, a brightness setting data D1 creation step S2, a brightness estimation data D2 creation step S3, a maximum brightness e2max calculation step S4, a grayscale setting data D3 creation step S5, and an image display step S6 on the liquid crystal panel 130. Each step will be described in detail below. Below, a method for displaying an image corresponding to a single input image IM on the liquid crystal panel 130 will be described. Note that when input images IM are sequentially input to the controller 150 and images corresponding to each input image IM are sequentially displayed on the liquid crystal panel 130, the following steps S1 to S6 are repeated.

[0050] First, let's explain the process S1 for acquiring the input image IM. As shown in Figure 5, the input interface 151 of the controller 150 acquires an input image IM from an external device 900. The acquired input image IM is stored in the memory 152.

[0051] Figure 7 is a schematic diagram showing the input image input to the controller in the image display device according to this embodiment. Figure 8 is a schematic diagram showing the relationship between the pixels of the input image input to the controller, the light-emitting area of ​​the backlight, and the pixels of the liquid crystal panel in the image display device according to this embodiment.

[0052] The input image IM has multiple pixels IMp arranged in a matrix. In the following explanation, for clarity, in data where elements such as pixels IMp are arranged in a matrix, such as the input image IM, the direction of the element arrangement will be represented using the xy Cartesian coordinate system. The direction of the arrow on the x-axis will be called the "+x direction," and the opposite direction will be called the "-x direction." Similarly, the direction of the arrow on the y-axis will be called the "+y direction," and the opposite direction will be called the "-y direction." In the following explanation, the group of elements in a matrix arranged in the x direction will be called a "row," and the group of elements in a matrix arranged in the y direction will be called a "column." For example, as shown in Figure 7, the row located furthest in the +y direction (the leftmost row) will be called the "first row," and the row located furthest in the -y direction (the rightmost row) will be called the "last row." Similarly, as shown in Figure 7, the column located furthest in the -x direction (the column located at the bottom) is designated as the "first column," and the column located furthest in the +x direction (the column located at the top) is designated as the "last column."

[0053] Furthermore, to make the explanation easier to understand, we will describe an example in which one pixel IMp of the input image IM corresponds to one pixel 130p of the liquid crystal panel 130, as shown in Figure 8. That is, in this embodiment, multiple pixels IMp are arranged to form N2 rows and M2 columns. In the input image IM, the image areas IMs corresponding to one light-emitting area 110s of the backlight 110 contain multiple pixels IMp. However, the correspondence between pixels of the input image and pixels of the liquid crystal panel does not have to be one-to-one. In this case, the processor 153 of the controller 150 performs preprocessing on the input image so that there is a one-to-one correspondence between pixels of the input image and pixels of the liquid crystal panel, and then performs the following processing.

[0054] Each pixel 130p has a grayscale assigned to it. In this embodiment, the input image IM is a color image. Therefore, as shown in Figure 7, the pixels IMp located in the i-th row and j-th column are assigned the grayscales Gb(i,j) for blue, Gg(i,j) for green, and Gr(i,j) for red. Here, i is any integer from 1 to N2, and j is any integer from 1 to M2. Each grayscale Gb(i,j), Gg(i,j), and Gr(i,j) is a number from 0 to 255, for example, when represented in 8 bits.

[0055] Next, we will explain the process S2 for creating the brightness setting data D1. Figure 9 is a schematic diagram showing the method for creating brightness setting data in the image display method according to this embodiment. The brightness setting data creation unit 153a creates brightness setting data D1 by converting the maximum grayscale Gmax of the grayscales Gb(i,j), Gg(i,j), and Gr(i,j) of multiple pixels IMp included in each image area IMs corresponding to each light emission region 110s of the input image IM into brightness L.

[0056] The following describes a specific example of how to create brightness setting data D1. First, the brightness setting data creation unit 153a extracts image areas IMs corresponding to the light-emitting regions 110s located in the nth row and mth column. Since one image area IMs corresponds to one light-emitting region 110s, in the input image IM, multiple image areas IMs are arranged to form N1 rows and M1 columns. Therefore, n is any integer between 1 and N1, and m is any integer between 1 and M1. Next, the brightness setting data creation unit 153a sets the maximum value of the blue gradation Gb(i,j), green gradation Gg(i,j), and red gradation Gr(i,j) of all pixels IMp contained in this image area IMs as the maximum gradation Gmax of this image area IMs. Next, the brightness setting data creation unit 153a converts this maximum gradation Gmax into brightness L. Next, the brightness setting data creation unit 153a sets this brightness L as the value of element e1(n,m) located in the nth row and mth column of the brightness setting data D1. The brightness setting data creation unit 153a performs this process for all image areas IMs.

[0057] The luminance setting data D1 obtained in this way is matrix data having N1 rows and M1 columns. The value of element e1(n,m) of the luminance setting data D1 located in the nth row and mth column is the value obtained by converting the maximum grayscale Gmax of the image area IMs located in the nth row and mth column to a luminance L. Also, the value of element e1(n,m) of the luminance setting data D1 located in the nth row and mth column is the luminance setting value of the light-emitting region 110s located in the nth row and mth column. The brightness setting data creation unit 153a stores the brightness setting data D1 in the memory 152.

[0058] The above describes a specific example of how to create the brightness setting data D1, but the method for creating the brightness setting data D1 is not limited to the above. For example, the brightness setting data creation unit 153a may use a value obtained by further correcting the brightness L described above as the value of each element e1(n,m) of the brightness setting data D1.

[0059] Figure 10 is a graph showing the brightness profile when a light source within a single light-emitting area is illuminated in the backlight of the image display device according to this embodiment. In Figure 10, the horizontal axis represents the position in the X direction, and the vertical axis represents brightness. In Figure 10, the light-emitting region 110s where the light source 114 is lit is shown as ON, and the light-emitting region 110s where the light source 114 is off is shown as OFF.

[0060] As shown in Figure 10, when a light source 114 within a single light-emitting region 110s is lit, the brightness within that light-emitting region 110s may not be constant at each position on the XY plane. Specifically, in this embodiment, since the center of the light source 114 is located approximately on the center of the light-emitting region 110s when viewed from above, the brightness decreases as you move away from the center of the light-emitting region 110s. Therefore, although multiple pixels 130p of the liquid crystal panel 130 are arranged on a single light-emitting region 110s, the brightness directly beneath these pixels 130p may not be the same.

[0061] Furthermore, in the planar light source 111 according to this embodiment, the space between adjacent light-emitting regions 110s is not completely shielded from light. Therefore, when a light source 114 within one light-emitting region 110s is lit in the backlight 110, the light emitted from this light source 114 can propagate to the surrounding light-emitting regions 110s. Thus, the brightness of each light-emitting region 110s may not be the value set by the brightness setting data D1, and may be affected by the light emitted by the light sources 114 in the surrounding light-emitting regions 110s.

[0062] Therefore, in this embodiment, brightness estimation data D2 is created by estimating the brightness directly below each pixel 130p, incorporating the brightness profile of the light source 114 within one light-emitting region 110s and the influence of the light emitted by the light source 114 within the surrounding light-emitting regions 110s. Then, based on the brightness estimation data D2, grayscale setting data D3 is created that defines the grayscale setting values ​​for each pixel 130p of the liquid crystal panel 130.

[0063] The following provides a detailed example of the process S3 for creating the luminance estimation data D2. Figure 11 is a schematic diagram showing the method for creating brightness estimation data in the image display method according to this embodiment. In this embodiment, the memory 152 has in advance stored a luminance profile D4 that shows the luminance distribution at each position on the XY plane when the light source 114 within one light-emitting region 110s is lit.

[0064] First, the brightness estimation data creation unit 153b estimates the brightness V(i,j) directly below the pixel 130p located in the i-th row and j-th column of the liquid crystal panel 130 from the brightness setting data D1 and the brightness profile D4.

[0065] Specifically, the luminance estimation data creation unit 153b estimates the luminance V1(i,j) directly below the pixel 130p when only the light source 114 within the light-emitting region 110s is lit, based on the value of element e1(n,m) (luminance setting value) corresponding to the light-emitting region 110s located directly below the pixel 130p in the luminance setting data D1 and the luminance profile D4. Furthermore, the luminance estimation data creation unit 153b estimates the luminance V2(i,j) directly below the pixel 130p when only the light source 114 within the surrounding light-emitting region 100s is lit, based on the value of element e1(k,l) corresponding to the light-emitting regions 110s surrounding the light-emitting region 110s in the luminance setting data D1 and the luminance profile D4. Here, k is any integer between 1 and N1, and l is any integer between 1 and M1. Then, the sum of these luminance values ​​V1(i,j) and V2(i,j) is estimated as the luminance V(i,j) directly below pixel 130p. In this way, the luminance estimation data creation unit 153b can estimate the luminance V(i,j) directly below pixel 130p by incorporating both the luminance distribution within a single light-emitting region 110s and the light leakage from the surrounding light-emitting regions 110s.

[0066] The luminance estimation data creation unit 153b sets the calculated luminance V(i,j) to the value of element e2(i,j) located in the i-th row and j-th column of the luminance estimation data D2. The luminance estimation data creation unit 153b performs the above process for all pixels 130p of the liquid crystal panel 130.

[0067] The luminance estimation data D2 obtained in this way is matrix data having N2 rows and M2 columns. The value of element e2(i,j) of the luminance estimation data D2 located in the i-th row and j-th column is the estimated luminance directly below the pixel 130p located in the i-th row and j-th column of the liquid crystal panel 130. The luminance estimation data creation unit 153b stores the luminance estimation data D2 in the memory 152.

[0068] The above describes a specific example of how to create luminance estimation data D2, but the method for creating luminance estimation data D2 is not limited to the above. For example, the luminance estimation data creation unit 153b may create a map that estimates the luminance distribution directly beneath all pixels 130p of the liquid crystal panel 130 when the backlight 110 is driven based on the luminance setting data D1, based on the luminance setting data D1 and the luminance profile D4. Then, the luminance estimation data creation unit 153b may create luminance estimation data D2 based on the created map.

[0069] Next, we will explain the calculation process S4 for the maximum brightness e2max. Figure 12 is a schematic diagram showing the method for calculating maximum brightness in the image display method according to this embodiment. The maximum luminance calculation unit 153c determines the maximum value of all luminances V(i,j) included in the luminance estimation data D2 as the maximum luminance e2max. The maximum luminance calculation unit 153c stores the maximum luminance e2max in the memory 152.

[0070] Next, we will explain the process S5 for creating the gradation setting data D3. Figure 13 is a schematic diagram showing a method for creating grayscale setting data in the image display method according to this embodiment. As shown in Figure 13, the gradation setting data creation unit 153d corrects the gradation Gb(i,j), Gg(i,j), and Gr(i,j) of each pixel IMp of the input image IM based on the luminance estimation data D2 and the maximum luminance e2max, thereby creating gradation setting data D3 that defines the gradation setting values ​​for each pixel 130p of the liquid crystal panel 130.

[0071] The following describes a specific example of how to create the gradation setting data D3. Figure 14A is a graph showing the relationship between normalized luminance and grayscale when normalized luminance is converted to grayscale based on a gamma correction conversion formula, with normalized luminance on the vertical axis and converted grayscale on the horizontal axis. This graph shows the case where the maximum value of normalized luminance is 1. Figure 14B is a graph showing the relationship between normalized luminance and grayscale when normalized luminance is converted to grayscale based on a gamma correction conversion formula, with normalized luminance on the vertical axis and converted grayscale on the horizontal axis. This graph shows the case where the maximum value of normalized luminance is less than 1. Figure 14C is a graph showing the relationship between normalized luminance and grayscale when normalized luminance is converted to grayscale based on a gamma correction conversion formula, with normalized luminance on the vertical axis and converted grayscale on the horizontal axis. This graph shows the case where the maximum value of normalized luminance exceeds 1.

[0072] When correcting the grayscale Gb(i,j), Gg(i,j), and Gr(i,j) of each pixel IMp in the input image IM based on the luminance estimation data D2, it is necessary to convert each luminance V(i,j) in the luminance estimation data D2 into grayscale Ga(i,j). The normalized luminance Vn(i,j) obtained by dividing the luminance V(i,j) by a predetermined value Vo can be converted into grayscale Ga(i,j) using the conversion formula Gf based on gamma correction shown below.

[0073]

number

[0074] The gamma correction conversion formula Gf is such that when the normalized luminance Vn(i,j) value is 1, the converted tone Ga(i,j) becomes the maximum value GEmax that tone Ga can take. The maximum value GEmax that tone Ga can take is, for example, 255 when tone Ga is represented by 8 bits, i.e., represented by numbers from 0 to 255. Therefore, if you want to convert each luminance V(i,j) in the luminance estimation data D2 to tone Ga(i,j), if you set the predetermined value Vo used for normalization to the maximum luminance e2max, the maximum value Vnmax of the normalized luminance Vn(i,j) will become 1, as shown in Figure 14A. As a result, the maximum value Vnmax can be converted to the maximum value GEmax that tone Ga can take. In other words, the converted tone Ga(i,j) can make the most of the range 0 to GEmax that tone Ga(i,j) can take.

[0075] However, while the maximum luminance e2max can vary depending on the input image IM, conventionally, since the maximum luminance e2max of each input image IM was unknown, a predetermined value Vo used during normalization was kept constant.

[0076] Therefore, depending on the input image IM, the maximum brightness e2max directly below the liquid crystal panel 130 may be less than a predetermined value Vo. In such cases, the maximum value Vnmax of the normalized brightness Vn(i,j) becomes less than 1. As a result, as shown in Figure 14B, the range of 0 to GEmax that the grayscale Ga(i,j) can inherently take may not be fully utilized.

[0077] Furthermore, depending on the input image IM, the maximum brightness e2max directly beneath the liquid crystal panel 130 may exceed a predetermined value Vo. In such cases, the maximum value Vnmax of the normalized brightness Vn(i,j) exceeds 1. The converted grayscale Ga(i,j) cannot take a value exceeding the maximum value GEmax. Therefore, when the normalized brightness Vn exceeds 1, the converted grayscale Ga(i,j) is rounded to GEmax as shown in Figure 14C. Thus, when the maximum brightness e2max directly beneath the liquid crystal panel 130 exceeds a predetermined value Vo, it becomes impossible to represent the difference in brightness V(i,j) that exceeds the predetermined value Vo with the converted grayscale Ga(i,j).

[0078] Therefore, in the image display method according to this embodiment, the luminance V(i,j) included in the luminance estimation data D2 is normalized by the maximum luminance e2max. That is, in the conversion formula Gf, Vo ​​= e2max. Then, the input image IM is corrected based on the normalized luminance V(i,j) / e2max obtained by dividing the luminance V(i,j) by the maximum luminance e2max.

[0079] Specifically, first, the gradation setting data creation unit 153d substitutes the maximum brightness e2max, the brightness V(i,j) of element e2(i,j) located in the i-th row and j-th column of the brightness estimation data D2, and the gradation G(i,j) of pixel IMp located in the i-th row and j-th column of the input image IM into the following equation (1) based on the conversion formula Gf.

[0080]

number

[0081] In the formula, Ex(i,j) is the grayscale setting value of the pixel located in the i-th row and j-th column of the liquid crystal panel. G(i,j) is the grayscale of the pixel located in the i-th row and j-th column of the input image. V(i,j) is the brightness of the element located in the i-th row and j-th column of the brightness estimation data. e2max is the maximum brightness. Gamma and a are constants.

[0082] The constant 'a' can be a positive or negative value. The constant 'a' is a unique value specific to each liquid crystal panel. The constant 'a' can be determined by pre-evaluating the liquid crystal panel. This evaluation can be performed, for example, by observing the brightness when a test pattern is displayed on the panel and calculating the constant 'a' based on that brightness.

[0083] The gradation setting data creation unit 153d uses the output value Exb(i,j) obtained by substituting the blue gradation Gb(i,j) for G(i,j) in the above equation (1) as the blue gradation setting value for pixel 130p, as shown in Figure 13.

[0084] The gradation setting data creation unit 153d uses the output value Exg(i,j) obtained by substituting the green gradation Gg(i,j) for G(i,j) in the above equation (1) as the green gradation setting value for pixel 130p, as shown in Figure 13.

[0085] The gradation setting data creation unit 153d sets the output value Exr(i,j) obtained by substituting the red gradation Gr(i,j) for G(i,j) in the above equation (1) as the red gradation setting value for pixel 130p, as shown in Figure 13.

[0086] The gradation setting data creation unit 153d uses these output values ​​Exb(i,j), Exg(i,j), and Exr(i,j) to set the value of element e3(i,j) located in the i-th row and j-th column of the gradation setting data D3. The gradation setting data creation unit 153d performs these processes for all pixels 130p of the liquid crystal panel 130.

[0087] The grayscale setting data D3 obtained in this way is matrix data having N2 rows and M2 columns. The value of element e3(i,j) of the grayscale setting data D3 located in the i-th row and j-th column is the grayscale setting value of pixel 130p located in the i-th row and j-th column of the liquid crystal panel 130. The gradation setting data creation unit 153d stores the gradation setting data D3 in the memory 152.

[0088] Figure 15 is a graph that schematically illustrates the correction of grayscale. In Figure 15, the vertical axis represents luminance, and the horizontal axis represents grayscale. As shown in Figure 15, for example, if the maximum brightness e2max directly below a pixel is 2.0 and the brightness V(i,j) directly below this pixel is 1.0, to set the brightness to the same level as when there are 150 gradations at the maximum brightness e2max, the gradation of this pixel is calculated based on equation (1) above. The setting value for the gradation of this pixel calculated based on equation (1) above is 205 + a(e2max - V(i,j)). In the example in Figure 15, since the constant a is a positive value, the calculated gradation is a value greater than 205. If the constant a is a negative value, the calculated gradation will be a value less than 205.

[0089] Thus, in the process S5 for creating the gradation setting data D3, the gradation setting data D3 is obtained for each pixel based on the above formula (1).

[0090] Next, the image display process S6 will be explained. The control unit 153e controls the backlight 110 based on the brightness setting data D1, controls the liquid crystal panel 130 based on the gradation setting data D3, and displays an image on the liquid crystal panel 130.

[0091] Specifically, as shown in Figure 5, the control unit 153e transmits backlight control data SG1, created based on brightness setting data D1, to the backlight driver 120 via the output interface 154. The backlight control data SG1 is not particularly limited as long as it is data that can control the driving of the backlight driver 120, but for example, it is data in PWM (Pulse Width Modulation) format. The backlight driver 120 controls the output of each light source 114 based on the backlight control data SG1.

[0092] Furthermore, the control unit 153e transmits the grayscale setting data D3 as liquid crystal panel control data SG2 to the liquid crystal panel driver 140 via the output interface 154. However, the liquid crystal panel control data SG2 may be data obtained by converting the grayscale setting data D3 into a format that can control the operation of the liquid crystal panel driver 140. Based on the liquid crystal panel control data SG2, the liquid crystal panel driver 140 controls the light transmittance of each pixel 130p, or more specifically, each subpixel 130sp.

[0093] The timing of converting brightness setting data D1 to backlight control data SG1 is not particularly limited as long as it is performed from process S2 onwards. Also, when converting grayscale setting data D3 to LCD panel control data SG2, the timing of the conversion is not particularly limited as long as it is performed from process S5 onwards.

[0094] Next, the effects of this embodiment will be described. The image display method according to this embodiment comprises a step S2 for creating brightness setting data D1, a step S3 for creating brightness estimation data D2, a step S4 for calculating maximum brightness e2max, a step S5 for creating gradation setting data D3, and a step S6 for displaying an image.

[0095] In step S2, brightness setting data D1 is created by using the input image IM input to the controller 150 of the backlight 110, which has multiple light-emitting regions 110s arranged in a matrix, and the liquid crystal panel 130, which has multiple pixels 130p, to define the brightness setting value for each light-emitting region 110s of the backlight 110. In step S3, brightness estimation data D2 is created by estimating the brightness directly below each pixel 130p of the liquid crystal panel 130, based on brightness setting data D1 and brightness profiles D4 of each light source 114 located in each light-emitting area 110s of the backlight 110. In step S4, the maximum luminance e2max of the luminance estimation data D2 is calculated. In step S5, the gradation of each pixel IMp of the input image IM is corrected using the above formula (1) based on the luminance estimation data D2 and the maximum luminance e2max, thereby creating gradation setting data D3 that defines the gradation setting value for each pixel 130p of the liquid crystal panel 130. In step S6, the backlight 110 is controlled using the brightness setting data D1, the liquid crystal panel 130 is controlled using the gradation setting data D3, and an image is displayed on the liquid crystal panel 130.

[0096] In this embodiment, the gradation setting value for each pixel 130p of the liquid crystal panel 130 is determined by correcting the gradation of each pixel IMp of the input image IM based on the luminance estimation data D2 and the maximum luminance e2max. Therefore, the gradation of each pixel IMp of the input image IM can be corrected by incorporating information about the maximum luminance e2max directly below the liquid crystal panel 130 corresponding to the input image IM. Furthermore, by correcting the gradation using the above formula (1), the gradation can be corrected while taking into account the differences between liquid crystal panels. This provides an image display method that can improve the contrast of the image displayed on the liquid crystal panel 130 and reduce luminance unevenness.

[0097] Furthermore, the image display device 100 according to this embodiment includes a backlight 110 having a planar light source 111 with a plurality of light-emitting regions 110s arranged in a matrix, each of which has a light source 114; a liquid crystal panel 130 located on the backlight 110 and having a plurality of pixels 130p; and a controller 150 that controls the backlight 110 and the liquid crystal panel 130. The controller 150 includes a brightness setting data creation unit 153a, a brightness estimation data creation unit 153b, a maximum brightness calculation unit 153c, and a gradation setting data creation unit 153d.

[0098] The brightness setting data creation unit 153a uses the input image IM to create brightness setting data D1 that defines the brightness setting values ​​for each light-emitting area 110s of the backlight 110. The luminance estimation data creation unit 153b creates luminance estimation data D2, which estimates the luminance directly below each pixel 130p of the liquid crystal panel 130, based on the luminance setting data D1 and the luminance profile D4 of each light source 114. The maximum luminance calculation unit 153c calculates the maximum luminance e2max of the luminance estimation data D2. The gradation setting data creation unit 153d creates gradation setting data D3, which defines the gradation setting value for each pixel 130p of the liquid crystal panel 130, by correcting the gradation of each pixel IMp of the input image IM using the above formula (1) based on the luminance estimation data D2 and the maximum luminance e2max. The control unit 153e controls the backlight 110 based on the brightness setting data D1, controls the liquid crystal panel 130 based on the gradation setting data D3, and displays an image on the liquid crystal panel 130.

[0099] Thus, in this embodiment, the gradation setting value for each pixel 130p of the liquid crystal panel 130 is determined by correcting the gradation of each pixel IMp of the input image IM based on the luminance estimation data D2 and the maximum luminance e2max. Therefore, the gradation of each pixel IMp of the input image IM can be corrected by incorporating information about the maximum luminance e2max corresponding to the input image IM. Furthermore, by correcting the gradation using the above formula (1), the gradation can be corrected while taking into account the differences between liquid crystal panels. Therefore, an image display device 100 can be provided that can improve the contrast of the image displayed on the liquid crystal panel 130 and reduce luminance unevenness.

[0100] <Second Embodiment> Next, a second embodiment will be described. Figure 16 is a schematic diagram showing the method for calculating the maximum brightness in the image display method according to this embodiment. Figure 17 is a schematic diagram showing a method for creating grayscale setting data in the image display method according to this embodiment. The image display method according to this embodiment differs from the image display method according to the first embodiment in the method for calculating the maximum brightness e2max(n,m) and the method for creating the gradation setting data D23. In the following explanation, we will, in principle, only describe the differences from the first embodiment. Except for the matters described below, it is the same as the first embodiment.

[0101] First, let's explain how to calculate the maximum brightness e2max(n,m). In the first embodiment, the maximum value among all luminances V(i,j) included in the luminance estimation data D2 was defined as the maximum luminance e2max. In contrast, in this embodiment, as shown in Figure 16, the maximum luminance e2max(n,m) for each area D2s corresponding to one or more light-emitting regions 110s in the luminance estimation data D2 is calculated.

[0102] In this embodiment, in the luminance estimation data D2, one area D2s corresponds to one light-emitting region 110s. Each area D2s contains multiple luminance values ​​V(i,j). However, in the luminance estimation data, one area may correspond to two or more light-emitting regions. Also, the number of corresponding light-emitting regions does not have to be the same for all areas.

[0103] Specifically, first, the maximum luminance calculation unit 153c extracts the area D2s located in the nth row and mth column of the luminance estimation data D2.

[0104] Next, the maximum brightness calculation unit 153c sets the maximum value of all brightness V(i,j) included in area D2s as the maximum brightness e2max(n,m).

[0105] Next, the maximum luminance calculation unit 153c determines the maximum luminance e2max(n,m) as the value of the element e25(n,m) located in the nth row and mth column of the matrix maximum luminance data D25 having N1 rows and M1 columns.

[0106] The maximum brightness calculation unit 153c performs the same process for all areas D2s. This creates the maximum brightness data D25. The maximum brightness calculation unit 153c stores the maximum brightness data D25 in the memory 152.

[0107] Next, we will explain how to create the gradation setting data D23. In the first embodiment, when creating gradation setting data D3 for each pixel 130p of the liquid crystal panel 130 based on the above formula (1), a common maximum brightness e2max was used. In contrast, in this embodiment, the gradation of each pixel IMp of the input image IM is corrected based on brightness estimation data D2 and the maximum brightness e2max(n,m) of area D2s to which each pixel 130p belongs among the multiple areas D2s. This creates gradation setting data D23 that defines the gradation setting value for each pixel 130p of the liquid crystal panel 130.

[0108] Specifically, first, the gradation setting data creation unit 153d substitutes the luminance V(i,j) of element e2(i,j) located in the i-th row and j-th column of the luminance estimation data D2, the gradation G(i,j) of pixel IMp located in the i-th row and j-th column of the input image IM, and the maximum luminance e2max(n,m) of area D2s to which element e2(i,j) located in the i-th row and j-th column of the maximum luminance data D25 belongs into the following formula (2).

[0109]

number

[0110] In the formula, Ex2(i,j) is the grayscale setting value for the pixel located in the i-th row and j-th column of the liquid crystal panel. G(i,j) is the grayscale of the pixel located in the i-th row and j-th column of the input image. V(i,j) is the brightness of the element located in the i-th row and j-th column of the brightness estimation data. e2max(n,m) is the maximum brightness. Gamma and a are constants.

[0111] The grayscale setting data creation unit 153d uses the output value Ex2b(i,j) obtained by substituting the blue grayscale Gb for G(i,j) in the above equation (2) as the blue grayscale setting value for pixel 130p located in the i-th row and j-th column of the liquid crystal panel 130.

[0112] The grayscale setting data creation unit 153d uses the output value Ex2g(i,j) obtained by substituting the green grayscale Gg for G(i,j) in the above equation (2) as the green grayscale setting value for pixel 130p located in the i-th row and j-th column of the liquid crystal panel 130.

[0113] The grayscale setting data creation unit 153d uses the output value Ex2r(i,j) obtained by substituting the red grayscale Gr for G(i,j) in the above formula (2) as the setting value for the red grayscale of pixel 130p located in the i-th row and j-th column of the liquid crystal panel 130.

[0114] The gradation setting data creation unit 153d uses these output values ​​Ex2b(i,j), Ex2g(i,j), and Ex2r(i,j) to set the value of element e23(i,j) located in the i-th row and j-th column of the gradation setting data D23. The gradation setting data creation unit 153d performs these processes for all pixels 130p of the liquid crystal panel 130.

[0115] The grayscale setting data D23 obtained in this way is matrix data having N2 rows and M2 columns. The value of element e23(i,j) of the grayscale setting data D23 located in the i-th row and j-th column is the grayscale setting value of pixel 130p located in the i-th row and j-th column of the liquid crystal panel 130. The gradation setting data creation unit 153d stores the gradation setting data D23 in the memory 152.

[0116] As described above, in step S3 of the image display method according to this embodiment, the maximum brightness e2max(n,m) of each area D2s corresponding to one or more light-emitting regions 110s is calculated in the brightness estimation data D2. In step S4, based on the brightness estimation data D2 and the maximum brightness e2max(n,m) of the area D2s to which each pixel 130p belongs, the gradation of each pixel IMp of the input image IM is corrected using the above formula (2) to create gradation setting data D23 which defines the gradation setting value of each pixel 130p of the liquid crystal panel 130.

[0117] In this way, the maximum brightness e2max(n,m) is calculated for each area D2s corresponding to one or more light-emitting regions 110s, and the gradation setting value for each pixel 130p of the liquid crystal panel 130 is determined for each area D2s using the maximum brightness e2max(n,m). Therefore, the gradation of each pixel 130p can be set to suit the maximum brightness e2max(n,m) for each area D2s. Furthermore, by correcting the gradation using the above formula (2), the gradation can be corrected while taking into account the differences between liquid crystal panels. Thus, an image display method can be provided that can improve the contrast of the image displayed on the liquid crystal panel 130 and reduce brightness unevenness.

[0118] Similarly, the maximum brightness calculation unit 153c of the image display device 100 according to this embodiment calculates the maximum brightness e2max(n,m) of each area D2s corresponding to one or more light-emitting regions 110s in the brightness estimation data D2. The grayscale setting data creation unit 153d then corrects the grayscale of each pixel IMp of the input image IM using the above formula (2) based on the brightness estimation data D2 and the maximum brightness e2max(n,m) of the area D2s to which each pixel 130p belongs, thereby creating grayscale setting data D23 that defines the grayscale setting value for each pixel 130p of the liquid crystal panel 130. Furthermore, by correcting the grayscale using the above formula (2), the grayscale can be corrected while taking into account the differences between liquid crystal panels. Therefore, an image display device 100 can be provided that can improve the contrast of the image displayed on the liquid crystal panel 130 and reduce brightness unevenness.

[0119] Figure 18A is a schematic diagram showing another example of an area in luminance estimation data. Figure 18B is a schematic diagram showing another example of an area in luminance estimation data. Figure 18C is a schematic diagram showing another example of an area in luminance estimation data.

[0120] In this embodiment, each area D2s corresponds to each light-emitting region 110s. However, as shown in Figures 18A to 18C, in the luminance estimation data D2, each area D2s may correspond to multiple light-emitting regions 110s.

[0121] As shown in Figure 18A, in one area D2s, the number of corresponding light-emitting regions 110s in the x-direction may be the same as the number of corresponding light-emitting regions 110s in the y-direction. Also, as shown in Figure 18B, in one area D2s, the number of corresponding light-emitting regions 110s in the x-direction may not be the same as the number of corresponding light-emitting regions 110s in the y-direction.

[0122] Furthermore, as shown in Figure 18C, the number of corresponding light-emitting regions 110s does not have to be the same in all areas D2s.

[0123] Examples and reference examples are described below. Figure 19A is a schematic diagram showing the brightness distribution of a reference example liquid crystal panel. Figure 19B is a schematic diagram showing the brightness distribution of the liquid crystal panel in the embodiment. Figure 19C is a table showing the brightness of the liquid crystal panel in the reference example and the liquid crystal panel in the embodiment.

[0124] In the reference example, the brightness of pixels P1 and P2 of the liquid crystal panel 130A, whose gradation was calculated using the following formula (3), was measured. In the embodiment, the brightness of pixels P1 and P2 of the liquid crystal panel 130B, whose gradation was calculated using the above formula (1), was measured.

[0125]

number

[0126] As shown in Figures 19A and 19C, in the reference example liquid crystal panel 130A, the brightness of pixel P1 was 40 nits and the brightness of pixel P2 was 32 nits, resulting in brightness unevenness. In contrast, as shown in Figures 19B and 19C, in the embodiment liquid crystal panel 130B, the brightness of pixel P1 was 30 nits and the brightness of pixel P2 was 30 nits, and no brightness unevenness occurred.

[0127] Thus, according to this embodiment, it is suggested that brightness unevenness can be reduced by correcting the gradation with the above formula (1).

[0128] In the above example, the brightness of the liquid crystal panel 130B, whose gradation was calculated using formula (1), is lower than the brightness of the liquid crystal panel 130A, whose gradation was calculated using formula (3). However, the brightness of the liquid crystal panel 130B, whose gradation was calculated using formula (1), may be higher than the brightness of the liquid crystal panel 130A, whose gradation was calculated using formula (3). [Industrial applicability]

[0129] The present invention can be used, for example, in displays for devices such as televisions, personal computers, or game consoles. [Explanation of symbols]

[0130] 100: Image display device 110: Backlight 110s: Emitting area 111: Planar light source 112: Circuit board 113: Light guide member 113a: Light source placement part 113b: Partition ditch 114 :Light source 114a: Light-emitting element 114b: Wavelength conversion component 114c: Semiconductor stack 114d, 114e: Electrode 114f: Translucent member 114g: Wavelength conversion material 114h: Second light adjustment member 114i: Third optical adjustment member 116: First light adjusting member 117: Light-reflecting material 118: Optical components 120: Driver for backlight 130: LCD panel 130p: pixels 130sp: subpixel 140: Driver for LCD panel 150: Controller 151: Input Interface 152: Memory 153: Processor 153a: Brightness setting data creation unit 153b: Luminance estimation data creation unit 153c: Maximum brightness calculation unit 153d: Tone setting data creation unit 153e: Control Unit 154: Output Interface 900: External equipment D1: Brightness setting data D2: Luminance estimation data D23: Tone setting data D25: Maximum brightness data D2s: Area corresponding to one or more light-emitting regions in the luminance estimation data. D3: Tone setting data D4: Brightness Profile Ex, Ex2, Exb, Exg, Exr, Ex2b, Ex2g, Ex2r: Output values ​​of the expression GEmax: Maximum possible value for gradation. G: Tone of input image Gb: Blue tone of the input image Gg: Green gradation of the input image Gr: Red tones of the input image Gmax: Maximum gradation of each image area in the input image. IM: Input image IMp: Pixel IMs: Image area L: Brightness SG1: Backlight control data SG2: LCD panel control data V: Brightness directly below Vn: Normalized luminance Vnmax: Maximum normalized brightness Vo: predetermined value e1: Element of brightness setting data e2: Elements of luminance estimation data e2max: Maximum brightness e3, e23: Elements of the gradation setting data e25: Element of maximum brightness data

Claims

1. A backlight having a planar light source having multiple light-emitting regions arranged in a matrix, with each of the multiple light-emitting regions having a light source, A liquid crystal panel having multiple pixels is located on the aforementioned backlight, A controller that controls the backlight and the liquid crystal panel, Equipped with, The aforementioned controller, A brightness setting data creation unit creates brightness setting data that defines set values ​​for the brightness of each of the light-emitting regions of the backlight using an input image. A luminance estimation data creation unit creates luminance estimation data that estimates the luminance directly below each pixel of the liquid crystal panel based on the luminance setting data and the luminance profile of each light source. A maximum brightness calculation unit that calculates the maximum brightness of the brightness estimation data, A gradation setting data creation unit creates gradation setting data that defines the gradation setting value for each pixel of the liquid crystal panel by correcting the gradation of each pixel of the input image using the following formula (1) based on the luminance estimation data and the maximum luminance. A control unit that controls the backlight based on the brightness setting data, controls the liquid crystal panel based on the grayscale setting data, and displays an image on the liquid crystal panel, An image display device having [Math 1] (In the formula, Ex(i,j) is the grayscale setting value of the pixel located in the i-th row and j-th column of the liquid crystal panel. G(i,j) is the grayscale of the pixel located in the i-th row and j-th column of the input image. V(i,j) is the brightness of the element located in the i-th row and j-th column of the brightness estimation data. e2max is the maximum brightness. Gamma and a are constants.)

2. A backlight having a planar light source having multiple light-emitting regions arranged in a matrix, with each of the multiple light-emitting regions having a light source, A liquid crystal panel having multiple pixels is located on the aforementioned backlight, A controller that controls the backlight and the liquid crystal panel, Equipped with, The aforementioned controller, A brightness setting data creation unit creates brightness setting data that defines brightness setting values ​​for each of the light-emitting regions of the backlight using an input image. A luminance estimation data creation unit creates luminance estimation data that estimates the luminance directly beneath each pixel of the liquid crystal panel based on the luminance setting data and the luminance profile of each light source. The luminance estimation data includes a maximum luminance calculation unit that calculates the maximum luminance of each area corresponding to one or more of the light-emitting regions, A gradation setting data creation unit creates gradation setting data that defines the gradation setting value for each pixel of the liquid crystal panel by correcting the gradation of each pixel of the input image using the following formula (2) based on the luminance estimation data and the maximum luminance of the area to which each pixel belongs among the plurality of areas, A control unit that controls the backlight based on the brightness setting data, controls the liquid crystal panel based on the grayscale setting data, and displays an image on the liquid crystal panel, An image display device having [Math 2] (In the formula, Ex2(i,j) is the grayscale setting value of the pixel located in the i-th row and j-th column of the liquid crystal panel. G(i,j) is the grayscale of the pixel located in the i-th row and j-th column of the input image. V(i,j) is the brightness of the element located in the i-th row and j-th column of the brightness estimation data. e2max(n,m) is the maximum brightness. Gamma and a are constants.)

3. The image display device according to claim 2, wherein each of the aforementioned areas corresponds to one of the aforementioned light-emitting regions.

4. A process of creating brightness setting data that defines a set value for the brightness of each light-emitting region of a backlight, using an input image input to a controller of a liquid crystal panel having multiple light-emitting regions arranged in a matrix, and multiple pixels, A step of creating brightness estimation data by estimating the brightness directly beneath each pixel of the liquid crystal panel based on the brightness setting data and the brightness profiles of each light source arranged in each of the light-emitting regions of the backlight, The process of calculating the maximum brightness of the aforementioned brightness estimation data, A step of creating gradation setting data that defines the gradation setting value for each pixel of the liquid crystal panel by correcting the gradation of each pixel of the input image using the following formula (1) based on the luminance estimation data and the maximum luminance, The steps include controlling the backlight based on the brightness setting data, controlling the liquid crystal panel based on the grayscale setting data, and displaying an image on the liquid crystal panel. An image display method comprising the following features. [Math 3] (In the formula, Ex(i,j) is the grayscale setting value of the pixel located in the i-th row and j-th column of the liquid crystal panel. G(i,j) is the grayscale of the pixel located in the i-th row and j-th column of the input image. V(i,j) is the brightness of the element located in the i-th row and j-th column of the brightness estimation data. e2max is the maximum brightness. Gamma and a are constants.)

5. A process of creating brightness setting data that defines the brightness setting value for each light-emitting region of a backlight, using an input image input to a controller of a liquid crystal panel having multiple light-emitting regions arranged in a matrix, and multiple pixels, A step of creating brightness estimation data by estimating the brightness directly beneath each pixel of the liquid crystal panel based on the brightness setting data and the brightness profiles of each light source provided in each of the light-emitting regions of the backlight, The steps include calculating the maximum brightness of each area corresponding to one or more of the light-emitting regions in the brightness estimation data, A step of creating gradation setting data that defines the gradation setting value for each pixel of the liquid crystal panel by correcting the gradation of each pixel of the input image using the following formula (2) based on the luminance estimation data and the maximum luminance of the area to which each pixel belongs among the plurality of areas, The process of controlling the backlight based on the brightness setting data, controlling the liquid crystal panel based on the grayscale setting data, and displaying an image, An image display method comprising the following features. [Math 4] (In the formula, Ex2(i,j) is the grayscale setting value of the pixel located in the i-th row and j-th column of the liquid crystal panel. G(i,j) is the grayscale of the pixel located in the i-th row and j-th column of the input image. V(i,j) is the brightness of the element located in the i-th row and j-th column of the brightness estimation data. e2max(n,m) is the maximum brightness. Gamma and a are constants.)

6. The image display method according to claim 5, wherein each of the aforementioned areas corresponds to one of the aforementioned light-emitting regions.

Images