Patent Publication Number: US-10770008-B2

Title: Display device with dimming panel

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority from Japanese Application No. 2017-147636, filed on Jul. 31, 2017 and Japanese Application No. 2017-198019, filed on Oct. 11, 2017, the contents of which are incorporated by reference herein in its entirety. 
     BACKGROUND 
     1. Technical Field 
     The present invention relates to a display device. 
     2. Description of the Related Art 
     In display devices illuminated by light from a back surface side thereof, a configuration is known in which an additional panel capable of controlling the transmittance of the light is provided between a display panel and a light source in order to reduce leakage of the light, as described in Japanese Patent Application Laid-open Publication No. 2015-191053. 
     Such an additional panel may have partial regions that are individually controlled in transmittance. If the transmittance differs between adjacent partial regions of this additional panel, a difference in light quantity occurs corresponding to the difference in the transmittance. Such a difference in light quantity is viewed as a belt-like halo along the position between the adjacent partial regions, in some cases. Such a belt-like halo causes problems, such as a reduction in contrast and deterioration in display quality. 
     SUMMARY 
     According to an aspect, a display device includes: a display panel comprising a plurality of pixels; a light guide plate provided on a back surface side of the display panel; a light source configured to emit light from a lateral side of the light guide plate; a dimming panel provided on a display panel side of the light guide plate; and a controller configured to control operations of at least the display panel and the dimming panel. The dimming panel comprises a plurality of dimming areas arranged in an emission direction of the light from the light source. The dimming areas are capable of individually changing transmittance of the light according to intensities of light required to display an image using the display panel. When adjacent two of the dimming areas differ in light transmittance from each other, the controller increases output gradation values of target pixels, the target pixels being located in a predetermined area extending from a boundary between the two dimming areas in one of the two dimming areas that has lower light transmittance. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram illustrating an exemplary main configuration of a display device according to a first embodiment of the present invention; 
         FIG. 2  is a diagram illustrating an exemplary positional relation of an image display panel, a dimming panel, and a light source device; 
         FIG. 3  is a diagram illustrating an example in which a polarizing plate is provided on a display surface side of the dimming panel; 
         FIG. 4  is a diagram illustrating an exemplary pixel array of the image display panel; 
         FIG. 5  is a schematic diagram illustrating an exemplary sectional structure of the image display panel; 
         FIG. 6  is a diagram illustrating an exemplary relation between a display area and display segment regions; 
         FIG. 7  is a diagram illustrating an exemplary main configuration of the light source device; 
         FIG. 8  is a diagram illustrating another exemplary configuration of the light source device; 
         FIG. 9  is a diagram illustrating an exemplary relation between dimming areas included in the dimming panel and coordinates in the Y-direction of the dimming areas; 
         FIG. 10  is a diagram illustrating an exemplary main configuration of a dimmer; 
         FIG. 11  is a diagram illustrating another exemplary main configuration of the dimmer; 
         FIG. 12  is a schematic diagram illustrating an exemplary sectional structure of the dimming panel; 
         FIG. 13  is a diagram illustrating an exemplary luminance distribution (light source luminance distribution) obtained by light from a light source; 
         FIG. 14  is a diagram illustrating an example of transmittance of the image display panel that outputs an image under the condition that the light source luminance distribution illustrated in  FIG. 13  is obtained; 
         FIG. 15  is a diagram illustrating output luminance of the display device when the image display panel is operated so as to have the transmittance of the image display panel illustrated in  FIG. 14  under the condition that the light source luminance distribution illustrated in  FIG. 13  is obtained; 
         FIG. 16  is a schematic diagram obtained by magnifying a range A of  FIG. 15  when reduction of luminance by the dimming panel is not taken into account; 
         FIG. 17  is a schematic diagram illustrating an example of the area that light from the light source reaches; 
         FIG. 18  is a diagram illustrating an example of transmittance of the dimming panel; 
         FIG. 19  is a magnified schematic diagram of the output luminance obtained when the dimming panel having the transmittance illustrated in  FIG. 18  is interposed between the light source device having the light source luminance distribution illustrated in  FIG. 13  and the image display panel having the transmittance illustrated in  FIG. 14 ; 
         FIG. 20  is a schematic diagram illustrating an example of an abrupt change line of the output luminance; 
         FIG. 21  is a diagram illustrating an example of the transmittance of the image display panel that outputs the image under the condition that the light source luminance distribution illustrated in  FIG. 13  and the transmittance of the dimming panel illustrated in  FIG. 18  are obtained in the first embodiment; 
         FIG. 22  is a magnified schematic diagram of the output luminance obtained when the dimming panel having the transmittance illustrated in  FIG. 18  is interposed between the light source device having the light source luminance distribution illustrated in  FIG. 13  and the image display panel having the transmittance illustrated in  FIG. 21 ; 
         FIG. 23  is a block diagram illustrating an exemplary functional configuration of a signal processor; 
         FIG. 24  is a flowchart of processing by the signal processor; 
         FIG. 25  is a diagram schematically illustrating an example of processing details of Step S 1  to Step S 5  in the flowchart illustrated in  FIG. 24 ; 
         FIG. 26  is a flowchart of calculation processing of output gradation values in  FIG. 24 ; 
         FIG. 27  is a block diagram illustrating another exemplary functional configuration of a signal processor in a modification; 
         FIG. 28  is a flowchart of processing by the signal processor of the modification; 
         FIG. 29  is a diagram schematically illustrating an example of processing details performed at Step S 11  to Step S 15  in the flowchart illustrated in  FIG. 28 ; 
         FIG. 30  is a diagram schematically illustrating an example of processing details performed at Step S 16  to Step S 18  in the flowchart illustrated in  FIG. 28 ; 
         FIG. 31  is a diagram illustrating an exemplary light source device according to a second embodiment of the present invention; 
         FIG. 32  is a diagram illustrating another exemplary light source device of the second embodiment; 
         FIG. 33  is a diagram illustrating still another exemplary light source device of the second embodiment; 
         FIG. 34  is a diagram illustrating an exemplary main configuration of a dimmer according to the second embodiment; 
         FIG. 35  is a schematic diagram illustrating an example of display output; 
         FIG. 36  is a schematic diagram illustrating an exemplary light source luminance distribution corresponding to the display output illustrated in  FIG. 35 ; 
         FIG. 37  is a schematic diagram illustrating a case where abrupt change lines of the output luminance are generated in the light source luminance distribution illustrated in  FIG. 36 ; 
         FIG. 38  is a flowchart of processing by the signal processor of the second embodiment; 
         FIG. 39  is a diagram schematically illustrating an example of processing details of Step S 21  to Step S 25  in the flowchart illustrated in  FIG. 38 ; 
         FIG. 40  is a flowchart of the calculation processing of the output gradation values in  FIG. 38 ; and 
         FIG. 41  is a diagram illustrating examples of preprocessing coefficients used for calculating the gradation values of target pixels in the second embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     The following describes embodiments of the present invention with reference to the drawings. What is disclosed herein is merely an example, and the present invention naturally encompasses appropriate modifications easily conceivable by those skilled in the art while maintaining the gist of the invention. To further clarify the description, widths, thicknesses, shapes, and the like of various parts are schematically illustrated in the drawings as compared with actual aspects thereof, in some cases. However, they are merely examples, and interpretation of the present invention is not limited thereto. The same element as that illustrated in a drawing that has already been discussed is denoted by the same reference numeral through the description and the drawings, and detailed description thereof will not be repeated in some cases where appropriate. 
     In this disclosure, when an element is described as being “on” another element, the element can be directly on the other element, or there can be one or more elements between the element and the other element. 
     First Embodiment 
       FIG. 1  is a diagram illustrating an exemplary main configuration of a display device  1  according to the first embodiment of the present invention. The display device  1  of the first embodiment includes a signal processor  10 , a display unit  20 , a light source device  50 , a light source control circuit  60 , and a dimmer  70 . The signal processor  10  performs various output operations based on input signals IP received from an external control device  2 , and controls operations of the display unit  20 , the light source device  50 , and the dimmer  70 . The input signals IP are signals serving as data for outputting an image for display on the display device  1 , and are, for example, red, green, and blue (RGB) image signals. The signal processor  10  outputs output image signals OP generated based on the input signals IP to the display unit  20 . The signal processor  10  outputs local dimming signals DI generated based on the input signals IP to the dimmer  70 . After receiving the input signals IP, the signal processor  10  outputs light source drive signals BL for controlling lighting amounts (light quantities) of respective light sources  51  (refer to  FIG. 7 ) included in the light source device  50  to the light source control circuit  60 . The light source control circuit  60  is, for example, a driver circuit for lighting up the light sources  51  (refer to  FIG. 7 ) included in the light source device  50 , and operates the light source device  50  according to the light source drive signals BL. 
     The display unit  20  includes an image display panel  30  and an image display panel driver  40 . The image display panel  30  includes a display area OA provided with pixels  48 . The pixels  48  are arranged, for example, in a matrix (row-column configuration). The image display panel  30  of the first embodiment is a liquid crystal image display panel. The image display panel driver  40  includes a signal output circuit  41  and a scanning circuit  42 . The signal output circuit  41  drives the pixels  48  according to the output image signals OP. The scanning circuit  42  outputs a drive signal for scanning the pixels  48  arranged in a matrix on a per predetermined number of lines basis (such as on a per row basis). The pixels  48  are driven so as to output gradation values corresponding to the output image signals OP at the time when the drive signal is output. 
     The dimmer  70  adjusts the quantity of light emitted from the light source device  50  and output through the display area OA. The dimmer  70  includes a dimming panel  80  and circuitry  90 . The dimming panel  80  includes a local dimming area DA capable of changing the transmittance of the light. The local dimming area DA is disposed in a position overlapping the display area OA when the display area OA is viewed in a plan view. The local dimming area DA covers the entire display area OA in the plan view. The local dimming area DA includes a plurality of dimming areas LD (refer to  FIG. 9 ). The circuitry  90  individually controls the transmittance of each of the dimming areas LD according to the local dimming signals DI. 
       FIG. 2  is a diagram illustrating an exemplary positional relation of the image display panel  30 , the dimming panel  80 , and the light source device  50 . In the first embodiment, as illustrated in  FIG. 2 , the image display panel  30 , the dimming panel  80 , and the light source device  50  are layered. Specifically, the dimming panel  80  is stacked on a light-emitting surface side of the light source device  50  from which the light is emitted. The image display panel  30  is stacked on the light source device  50  with the dimming panel  80  therebetween. The light emitted from the light source device  50  is adjusted in light quantity in the local dimming area DA of the dimming panel  80 , and illuminates the image display panel  30 . The image display panel  30  is illuminated from a back surface side thereof where the light source device  50  lies, and outputs the image for display to a side (display surface side) opposite to the back surface side. In this manner, the light source device  50  serves as a backlight that illuminates the display area OA of the image display panel  30  from the back surface thereof. In the first embodiment, the dimming panel  80  is provided between the image display panel  30  and the light source device  50 . Hereinafter, the Z-direction refers to the direction in which the image display panel  30 , the dimming panel  80 , and the light source device  50  are layered. The X-direction and the Y-direction refer to two directions orthogonal to the Z-direction. The X-direction and the Y-direction are orthogonal to each other. The pixels  48  are arranged in a matrix along the X- and Y-directions. In the following description, h denotes the number of the pixels  48  arranged in the X-direction, and v denotes the number of the pixels  48  arranged in the Y-direction. A notation (h) represents a case where coordinate management in the X-direction is performed corresponding to positions of the pixels  48  arranged in the X-direction. A notation (v) represents a case where the coordinate management in the Y-direction is performed corresponding to positions of the pixels  48  arranged in the Y-direction. A notation (h,v) represents a case where the coordinate management in the X-direction and the Y-direction is performed corresponding to the positions of the pixels  48  arranged in the X-direction and the Y-direction. 
     The image display panel  30  includes an array substrate  30   a  and a counter substrate  30   b  that is located on a display surface side of the array substrate  30   a  and faces the array substrate  30   a . As will be described later, a liquid crystal layer LC 1  is disposed between the array substrate  30   a  and the counter substrate  30   b  (refer to  FIG. 5 ). A polarizing plate  30   c  is provided on a back surface side of the array substrate  30   a . A polarizing plate  30   d  is provided on a display surface side of the counter substrate  30   b . The dimming panel  80  includes a first substrate  80   a  and a second substrate  80   b  that is located on a display surface side of the first substrate  80   a  and faces the first substrate  80   a . As will be described later, a liquid crystal layer LC 2  is disposed between the first substrate  80   a  and the second substrate  80   b  (refer to  FIG. 12 ). A polarizing plate  80   c  is provided on a back surface side of the first substrate  80   a . The polarizing plate  30   c  polarizes light both on the back surface side of the image display panel  30  and on a display surface side of the dimming panel  80 . 
       FIG. 3  is a diagram illustrating an example in which a polarizing plate  80   d  is provided on the display surface side of the dimming panel  80 . As illustrated in  FIG. 3 , the polarizing plate  80   d  may be provided on a display surface side of the second substrate  80   b.    
       FIG. 4  is a diagram illustrating an exemplary pixel array of the image display panel  30 . As illustrated in  FIG. 4 , each of the pixels  48  includes, for example, a first sub-pixel  49 R, a second sub-pixel  49 G, and a third sub-pixel  49 B. The first sub-pixel  49 R displays a first primary color (for example, red). The second sub-pixel  49 G displays a second primary color (for example, green). The third sub-pixel  49 B displays a third primary color (for example, blue). In this manner, each of the pixels  48  arranged in a matrix (in a row-column configuration) in the image display panel  30  includes the first sub-pixel  49 R that displays a first color, the second sub-pixel  49 G that displays a second color, and the third sub-pixel  49 B that displays a third color. The first color, the second color, and the third color are not limited to the first primary color, the second primary color, and the third primary color, but only need to be different colors from one another, such as complementary colors. In the following description, the first sub-pixel  49 R, the second sub-pixel  49 G, and the third sub-pixel  49 B will be each called a sub-pixel  49  when not necessary to be distinguished from one another. 
     Each of the pixels  48  may further include the sub-pixel  49 , in addition to the first sub-pixel  49 R, the second sub-pixel  49 G, and the third sub-pixel  49 B. For example, the pixel  48  may include a fourth sub-pixel that displays a fourth color. The fourth sub-pixel displays a fourth color (for example, white). The fourth sub-pixel is preferably brighter than the first sub-pixel  49 R that displays the first color, the second sub-pixel  49 G that displays the second color, and the third sub-pixel  49 B that displays the third color, when irradiated with the same light source lighting amount. 
     The display device  1  is more specifically a transmissive color liquid crystal display device. As illustrated in  FIG. 4 , the image display panel  30  is a color liquid crystal display panel, in which a first color filter for transmitting the first primary color is disposed between the first sub-pixel  49 R and an image viewer, a second color filter for transmitting the second primary color is disposed between the second sub-pixel  49 G and the image viewer, and a third color filter for transmitting the third primary color is disposed between the third sub-pixel  49 B and the image viewer. A filter film  26  (to be described later) has a configuration including the first color filter, the second color filter, and the third color filter. 
     In the case where the fourth sub-pixel is provided, no color filter is disposed between the fourth sub-pixel and the image viewer. In this case, a large level difference is generated at the fourth sub-pixel. In view of this, a transparent resin layer instead of the color filter may be provided on the fourth sub-pixel. This configuration can restrain the generation of the large level difference in the fourth sub-pixel. 
     The signal output circuit  41  is electrically coupled to the image display panel  30  through signal lines DTL. The image display panel driver  40  uses the scanning circuit  42  to select the sub-pixel  49  in the image display panel  30  and to control ON and OFF of a switching element (such as a thin-film transistor (TFT)) for controlling operations (light transmittance) of the sub-pixel  49 . The scanning circuit  42  is electrically coupled to the image display panel  30  through scanning lines SCL. In the first embodiment, the scanning lines SCL extend along the X-direction, and the signal lines DTL extend along the Y-direction. These are, however, mere examples of extension directions of the scanning lines SCL and the signal lines DTL. The extension directions are not limited thereto, and can be changed as appropriate. 
       FIG. 5  is a schematic diagram illustrating an exemplary sectional structure of the image display panel  30 . The array substrate  30   a  includes the filter film  26 , a counter electrode  23 , an insulating film  24 , pixel electrodes  22 , and a first orientation film  28 . The filter film  26  is provided on a pixel substrate  21 , such as a glass substrate. The counter electrode  23  is provided on the filter film  26 . The insulating film  24  is provided directly on the counter electrode  23  so as to be in contact therewith. The pixel electrodes  22  are provided on the insulating film  24 . The first orientation film  28  is provided on the uppermost surface side of the array substrate  30   a . The counter substrate  30   b  includes a counter pixel substrate  31 , such as a glass substrate, a second orientation film  38  provided on the lower surface of the counter pixel substrate  31 , and a polarizing plate  35  provided on the upper surface thereof. The array substrate  30   a  is fixed to the counter substrate  30   b  with a sealing part  29  interposed therebetween. The liquid crystal layer LC 1  is sealed in a space surrounded by the array substrate  30   a , the counter substrate  30   b , and the sealing part  29 . The liquid crystal layer LC 1  contains liquid crystal molecules that change in orientation direction according to an electric field applied thereto. The liquid crystal layer LC 1  modulates light passing through the inside of the liquid crystal layer LC 1  according to the state of the electric field. The electric field applied between the pixel electrodes  22  and the counter electrode  23  changes the orientations of the liquid crystal molecules of the liquid crystal layer LC 1 , and thus changes the transmission amount of the light passing through the liquid crystal layer LC 1 . The sub-pixels  49  include the respective pixel electrodes  22 . The switching elements for individually controlling the operations (light transmittance) of the sub-pixels  49  are electrically coupled to the pixel electrodes  22 . 
       FIG. 6  is a diagram illustrating an exemplary relation between the display area OA and display segment regions. The display area OA includes a plurality of display segment regions PA. The display area OA is an area obtained by combining the display segment regions PA. The display area OA illustrated in  FIG. 6  includes the display segment regions PA that are individually provided in positions corresponding to a total of 36 sets of coordinates corresponding to combinations of coordinates x 1 , x 2 , . . . , and x 9  set along the X-direction and coordinates y 1 , y 2 , y 3 , and y 4  set along the Y-direction. Hereinafter, in some cases, coordinates will be used to indicate positions of, for example, the display segment regions PA. For example, “display segment regions PA at (x 1 )” represent the display segment regions PA provided in positions having a coordinate of x 1  in the X-direction; “display segment regions PA at (y 1 )” represent the display segment regions PA provided in positions having a coordinate of y 1  in the Y-direction; and a “display segment region PA at (x 1 ,y 1 )” represents the display segment region PA provided in a position having a coordinate of x 1  in the X-direction and a coordinate of y 1  in the Y-direction. Positions of the light sources  51  and of light source regions GA and the dimming areas LD (both to be described later) will be indicated using the same kind of expression in some cases. 
     Of the coordinates of the display segment regions PA included in the display area OA, the coordinates in the X-direction correspond to the number of the light sources  51  included in the light source device  50  and the positions in the X-direction of the respective light sources  51  (refer to  FIG. 7 ). Of the coordinates of the display segment regions PA included in the display area OA, the coordinates in the Y-direction correspond to the number of the dimming areas included in the dimming panel  80  and the positions in the Y-direction of the respective dimming areas (refer to  FIG. 9 ). 
       FIG. 7  is a diagram illustrating an exemplary main configuration of the light source device  50 . The light source device  50  includes, for example, a light guide plate LA and the light sources  51 . The light guide plate LA is provided in a position corresponding to the display area OA in an XY-planar view on the back surface side of the image display panel  30 . The light sources  51  are arranged in the X-direction on one end side in the Y-direction. The light sources  51  emit light from a lateral side of the light guide plate LA. The light sources  51  are, for example, light-emitting diodes (LEDs) emitting white light, but are not limited thereto, and can be changed as appropriate. The light from the light sources  51  is guided by the light guide plate LA, and illuminates the entire display area OA from the back surface side thereof. 
     In the example illustrated in  FIG. 7 , the light sources  51  are individually arranged corresponding to the coordinates (x 1 , x 2 , . . . , and x 9 ) in the X-direction. The light guide plate LA includes the light source regions GA provided corresponding to the coordinates (x 1 , x 2 , . . . , and x 9 ) in the X-direction. When the light is emitted from the light sources  51 , the light source regions GA guide the light so as to illuminate the image display panel  30  from the back surface side of the display segment regions PA corresponding to the coordinates in the X-direction of the light source regions GA. The light source regions GA are assumed to guide the light from the respective light sources  51  at the corresponding coordinates (x 1 , x 2 , . . . , and x 9 ) in the X-direction. The following description of the lighting amount control of the light sources  51  will be given on the assumption that the light is emitted from the light sources  51  at the coordinates (x 1 , x 2 , . . . , and x 9 ) in the X-direction corresponding to the light source regions GA. 
     Each light source region GA can receive not only light from the light source  51  at a corresponding one of the coordinates (x 1 , x 2 , . . . , and x 9 ) in the X-direction but also light from the light sources at other coordinates in the X-direction not corresponding to the light source region GA. A lighting amount calculator  104  (refer to  FIG. 23 ) to be described later may have reference data for obtaining a relation between a luminance distribution of the light source regions GA and the lighting amount of each of the light sources  51  including that of the light from the light sources  51  at such non-corresponding coordinates. If having the reference data, the lighting amount calculator  104  uses the reference data when calculating the lighting amount of each of the light sources  51 . 
     In the first embodiment, the light sources  51  emit the light from one end side of the light guide plate LA. Specifically, in the first embodiment, as illustrated, for example, in  FIG. 7 , nine light sources  51  are provided, being arranged in a line along the X-direction on one end side in the Y-direction. The example illustrated in  FIG. 7  is a mere example of the number and the arrangement of the light sources  51 , which are not limited to this example, and can be changed as appropriate. 
       FIG. 8  is a diagram illustrating another exemplary configuration of the light source device  50 . For example, as illustrated in  FIG. 8 , a total of 18 light sources  51  may be disposed, being arranged in a line along the X-direction on each of one end side and the other end side in the Y-direction. In this manner, the display device  1  may include the light sources  51  provided in positions opposed to one another across the light guide plate LA. 
       FIG. 9  is a diagram illustrating an exemplary relation between the dimming areas LD included in the dimming panel  80  and the coordinates in the Y-direction of the dimming areas LD. The dimming panel  80  includes the dimming areas LD capable of individually controlling the transmittance of the light. The local dimming area DA is an area including the dimming areas LD. The dimming panel  80  is provided such that each of the dimming areas LD can individually control the transmittance of the light guided by the light guide plate LA and illuminating the entire display area OA from the bask surface side thereof. Thus, the dimming areas LD of the first embodiment extend in a direction (such as the X-direction) intersecting an emission direction (such as the Y-direction) of the light from the light sources  51  to the light guide plate LA. In the example illustrated in  FIG. 9 , four dimming areas LD arranged in the Y-direction are provided. The positions of the four dimming areas LD correspond to the coordinates (y 1 , y 2 , y 3 , and y 4 ) in the Y-direction. The number of the dimming areas LD illustrated in  FIG. 9  is a mere example, and is not limited thereto, but can be changed as appropriate. 
     As described above, each of the display segment regions PA arranged in the X-direction is irradiated with light from the light source region GA at a corresponding coordinate in the X-direction. Each of the display segment regions PA arranged in the Y-direction is controlled in the level of irradiation with the light from a corresponding one of the light source regions GA by the dimming area LD at a corresponding one of the coordinates in the Y-direction. 
       FIG. 10  is a diagram illustrating an exemplary main configuration of the dimmer  70 . The dimming panel  80  includes a plurality of first electrodes  81  provided in the local dimming area DA. The dimming panel  80  illustrated in  FIG. 10  includes the first electrodes  81  individually provided in positions corresponding to 36 sets of coordinates, for example, corresponding to the combinations of the coordinates x 1 , x 2 , . . . , and x 9  set along the X-direction and the coordinates y 1 , y 2 , y 3 , and y 4  set along the Y-direction. Each of the first electrodes  81  is coupled to the circuitry  90  through wiring  86 . 
     The circuitry  90  of the first embodiment controls, for example, potentials of the first electrodes  81  at the same coordinate in the Y-direction so as to be uniform according to the local dimming signals DI. This control makes the transmittance of the dimming areas LD uniform in the longitudinal direction (X-direction). The circuitry  90  individually controls the potentials of the first electrodes  81  at different coordinates in the Y-direction. This control individually controls the transmittance of the dimming areas LD. 
       FIG. 11  is a diagram illustrating another exemplary main configuration of the dimmer. In  FIG. 10 , the first electrodes  81  are provided in positions corresponding to the coordinates in the X-direction. This is a mere example of a specific way of providing the first electrodes  81 . The specific way thereof is not limited to this example. For example, as illustrated in  FIG. 11 , first electrodes  81 A may be provided corresponding one-to-one to the dimming areas LD. In this case, the length in the X-direction of each first electrode  81 A provided in a corresponding one of the dimming areas LD corresponds to the length in the X-direction of the dimming area LD. 
       FIG. 12  is a schematic diagram illustrating an exemplary sectional structure of the dimming panel  80 . The dimmer  70  includes switches SW made of, for example, a TFT. Each of the switches SW includes a channel  84 , a source  85   a , a drain  85   b , and a gate  85   c  that are mounted on a first transparent substrate  83  of the first substrate  80   a . The source  85   a  is supplied with a potential based on the local dimming signal DI, that is, a potential corresponding to the transmittance of each of the dimming areas LD. The drain  85   b  is electrically coupled to the wiring  86 . The switch SW switches whether to conduct a drain current to a corresponding one of the first electrodes  81  according to whether a signal is applied to the gate  85   c . Although  FIG. 12  schematically illustrates an electrical coupling relation between one of the switches SW and one of the first electrodes  81 , each of the first electrodes  81  may be coupled to the drain  85   b  of the individual switch SW through the individual wiring  86 . 
     Each of the dimming areas LD includes corresponding ones of the first electrodes  81  and a second electrode  82  provided in a position opposed to the first electrodes  81  with the liquid crystal layer LC 2  in between. Specifically, the first substrate  80   a  includes the first transparent substrate  83 , the semiconductor layer (channel)  84 , a first insulating layer  87   a , a second insulating layer  87   b , a third insulating layer  87   c , and the first electrodes  81 . The second insulating layer  87   b  is stacked on the gate  85   c  stacked on the first insulating layer  87   a . The third insulating layer  87   c  is stacked on the source electrode  85   a  and the drain electrode  85   b . The first electrodes  81  are stacked on the third insulating layer  87   c . The second substrate  80   b  includes a second transparent substrate  88  and the second electrode  82  stacked on the second transparent substrate  88 . The first substrate  80   a  and the second substrate  80   b  are disposed such that a surface provided with the first electrodes  81  is opposed to a surface provided with the second electrode  82 . The liquid crystal layer LC 2  is provided between the surface provided with the first electrodes  81  and the surface provided with the second electrode  82 . A seal material  89  for sealing the liquid crystal layer LC 2  is provided between the first substrate  80   a  and the second substrate  80   b . The first transparent substrate  83  and the second transparent substrate  88  are, for example, glass substrates. The first electrodes  81 , the second electrode  82 , and the wiring  86  are translucent electrodes made of, for example, indium tin oxide (ITO). 
     The second electrode  82  of the first embodiment has a structure shared by the dimming areas LD. Specifically, the second electrode  82  is a flat film-like electrode provided so as to cover the entire local dimming area DA across the dimming areas LD. The potential of each of the first electrodes  81  in the dimming areas LD is individually controlled with respect to the potential of the second electrode  82  shared by the dimming areas LD, whereby the extent of twist of the liquid crystals in each of the dimming areas LD is individually controlled. This control individually controls the light transmittance levels of the respective dimming areas LD according to the local dimming signals DI. 
     The dimming panel  80  of the first embodiment is a twisted nematic (TN) liquid crystal panel, and transmits light at the maximum transmittance when no current flows therethrough (that is, normally white). This is a mere example of a specific form of the dimming panel  80 , which is not limited to this example. The dimming panel  80  may be a liquid crystal panel of another type, and may be a normally black panel. The form of the second electrode  82  described above is a mere example of a specific form of the second electrode  82 , which is not limited to this example, and can be changed as appropriate. For example, the second electrode  82  may be individually provided in each of the dimming areas LD in the same manner as the first electrode  81 . In this case, potentials of the respective individually provided second electrodes  82  are controlled so as to be the same potential at the same time. 
     The circuitry  90  deals with electrical signals for controlling the transmittance of each of the dimming areas LD. The circuitry  90  is mounted using, for example, a chip-on-glass (COG) technique, for example, in a frame area of the dimming panel  80  of the dimmer  70  where the local dimming area DA is not located. The circuitry  90  is coupled to each of the first electrodes  81  through the wiring  86 . In this manner, the circuit for individually controlling the transmittance of each of the dimming areas LD is provided outside the local dimming area DA. As a result, the maximum light transmittance in the local dimming area DA can be more easily increased. 
       FIG. 13  is a diagram illustrating an exemplary luminance distribution (light source luminance distribution) obtained by the light from a light source.  FIG. 14  is a diagram illustrating an example of the transmittance of the image display panel  30  that outputs the image under the condition that the light source luminance distribution illustrated in  FIG. 13  is obtained.  FIG. 15  is a diagram illustrating output luminance of the display device  1  when the image display panel  30  is operated so as to have the transmittance of the image display panel  30  illustrated in  FIG. 14  under the condition that the light source luminance distribution illustrated in  FIG. 13  is obtained. For example, as illustrated in  FIG. 15 , assume a case where one or more colors have output luminance corresponding to a gradation value of 100[%] in some of the display segment regions PA at (y 1 ) closest in coordinates in the Y-direction to the light source  51 . This case is assumed to be a case where the image is displayed in black ((R,G,B)=(0,0,0)) except in some of the display segment regions PA. In this case, the display segment regions PA at (y 1 ) need to have luminance of 100[%] or higher. In the display segment regions PA at (y 2 ), (y 3 ), and (y 4 ), all the gradation values of the pixels  48  included in the input signals IP are (R,G,B)=(0,0,0), and thus, no light is needed from the light sources  51 . In this case, if luminance of 100[%] is ensured at the boundary between the display segment regions PA at (y 1 ) and the display segment regions PA at (y 2 ) as illustrated in  FIG. 13 , the output luminance of the display segment regions PA at (y 1 ) can be sufficiently ensured. When the light source  51  is on, the light source  51  illuminates a closer position more brightly. As a result, the output luminance of the display segment regions PA at (y 1 ) is higher than the luminance of the boundary between the display segment regions PA at (y 1 ) and the display segment regions PA at (y 2 ). 
     In  FIG. 13 , the light source  51  is lit at an intensity of 120[%] in order to ensure the luminance of 100[%] in the entire display segment regions PA at (y 1 ).  FIG. 13  illustrates that the luminance of the light decreases as the coordinate position is farther away from (y 1 ) to y 2 , y 3 , and y 4 .  FIG. 13  illustrates the example in which the luminance is 60[%] at an end in the Y-direction of the display segment regions PA at (y 4 ) farthest from the light source  51 . In consideration of the fact that the luminance of the light changes with the distance from the light source  51  in this manner, the transmittance of the image display panel  30  is multiplied by a gain based on the inverse of the luminance (inverse luminance gainpix(h,v) to be described later). Specifically, output gradation values of each of the pixels of the image display panel  30  are multiplied by the gain. In  FIG. 14 , the gain is multiplied so as to increase the transmittance of the image display panel  30  from one end side toward the other end side in response to the reduction in the luminance from one end side toward the other end side in  FIG. 13 . By combination of the luminance of the light from the light source  51  ( FIG. 13 ) with the transmittance multiplied by the gain (refer to  FIG. 14 ), the output luminance can be set to 100[%] in the display segment regions PA at (y 1 ), as illustrated in  FIG. 15 . 
     As illustrated, for example, in  FIG. 14 , the image display panel  30  is capable of changing the transmittance within a range with maximum transmittance (DP_max) serving as the upper limit and minimum transmittance (DP_min) serving as the lower limit. When the gradation value of each of (R,G,B) is expressed by a predetermined number of bits (such as 8 bits of 0 to 255), the maximum transmittance (DP_max) is transmittance corresponding to the maximum gradation value (255) representable by the number of bits, and the minimum transmittance (DP_min) is transmittance corresponding to the minimum gradation value (0) representable by the number of bits. Hereinafter, a “first contrast (DP-c, refer to  FIG. 21 )” denotes a value related to the ratio between the maximum transmittance (DP_max) and the minimum transmittance (DP_min) of the image display panel  30 . The first contrast represents the “contrast of the image display panel  30 ”, and is given as, for example, DP_c=DP_max/DP_min. Assuming that DP_c=1000, the minimum transmittance (DP_min) of the image display panel  30  is 1/1000 of the maximum transmittance (DP_max) thereof. In other words, the light transmittance of the image display panel  30  is not zero at the minimum transmittance (DP_min). 
       FIG. 16  is a schematic diagram obtained by magnifying a range A of  FIG. 15  when control of the contrast by the dimming panel  80  is not taken into account. As described above, the light transmittance of the image display panel  30  is not zero even at the minimum transmittance (DP_min). Therefore, if the dimming panel  80  is not provided, even when the pixels  48  are controlled so as to have the minimum transmittance (DP_min) corresponding to (R,G,B)=0, a phenomenon called black floating (insufficient black level caused by light leakage) U occurs corresponding to a gap in the output luminance between a state of completely no light (at 0[%] in the graph of  FIG. 16 ) and the minimum transmittance (DP_min). As a specific example, an output luminance value of approximately 0.1[%] is obtained by the black floating U of the image display panel  30  having the first contrast of 1000. 
       FIG. 17  is a schematic diagram illustrating an example of the area that light from the light source  51  reaches. A boundary line LDL between the adjacent dimming areas is illustrated in  FIG. 17  and other figures. As described with reference to  FIG. 13 , the luminance of the light from the light source  51  decreases as the distance from the light source  51  increases. Hence, the degree of the black floating U also changes with the distance from the light source  51 , as illustrated in the graph of  FIG. 16  and the schematic diagram of  FIG. 17 . The black floating U described above is known as what is called a halo effect. 
       FIG. 18  is a diagram illustrating an example of the transmittance of the dimming panel  80 . The dimming panel  80  is capable of changing the transmittance within a range with maximum transmittance (BL_max) serving as the upper limit and minimum transmittance (BL_min) serving as the lower limit. Hereinafter, a “second contrast (BL_c, refer to  FIG. 21 )” denotes a value related to the ratio between the maximum transmittance (BL_max) and the minimum transmittance (BL_min) of the dimming panel  80 . The second contrast represents the “contrast of the dimming panel  80 ”, and is given as, for example, BL_c=BL_max/BL_min. Assuming that BL_c=500, the minimum transmittance (BL_min) of the dimming panel  80  is 1/500 of the maximum transmittance (BL_max) thereof. 
       FIG. 19  is a magnified schematic diagram of the output luminance obtained when the dimming panel  80  having the transmittance illustrated in  FIG. 18  is interposed between the light source device having the light source luminance distribution illustrated in  FIG. 13  and the image display panel  30  having the transmittance illustrated in  FIG. 14 . To obtain the output luminance illustrated in  FIG. 15 , the display segment regions PA at (y 2 ), (y 3 ), and (y 4 ) do not need the light. Therefore, as illustrated in  FIG. 18 , the dimming panel  80  is operated such that the dimming areas LD at (y 2 ), (y 3 ), and (y 4 ) have the minimum transmittance (BL_min), whereby the output luminance can be further reduced at (y 2 ), (y 3 ), and (y 4 ). Specifically, as illustrated in  FIG. 19 , the output luminance of the display segment regions PA at (y 2 ), (y 3 ), and (y 4 ) can be reduced to output luminance corresponding to the product of the minimum transmittance (DP_min) of the image display panel  30  and the minimum transmittance (BL_min) of the dimming panel  80 . For example, assume that the quantity of the light can be reduced to a lowered rate of approximately 0.2[%] by setting the transmittance of the dimming panel  80  having the second contrast of 500 to the minimum transmittance (BL_min). In this case, the output luminance of the display segment regions PA at (y 2 ), (y 3 ), and (y 4 ) can be reduced to 0.0002[%] by combining the image display panel  30  having the first contrast of 1000 with the dimming panel  80  having the second contrast of 500. In this manner, using the dimming panel  80  can restrain the black floating U such as that illustrated in  FIG. 16 . 
     Since the output luminance of 100[%] is needed at (y 1 ), the transmittance of the dimming area LD at (y 1 ) is set to the maximum transmittance (BL_max). As a result, unlike in the display segment regions PA at (y 2 ), (y 3 ), and (y 4 ), the black floating U is not restrained by the dimming panel  80  in regions of the display segment regions PA at (y 1 ) other than the regions having the output luminance of 100[%], as illustrated in  FIG. 19 . As a result, an abrupt change line ST 1  of the output luminance is generated at the boundary between the display segment regions PA at (y 1 ) and the display segment regions PA at (y 2 ). 
       FIG. 20  is a schematic diagram illustrating an example of the abrupt change line ST 1  of the output luminance. When the abrupt change line ST 1  of the output luminance is generated, the boundary line LDL between the adjacent dimming areas LD serves as the boundary between the area in which the black floating U is restrained by the dimming panel  80  and the area in which the black floating U is not restrained, and the luminance difference between those areas is sometimes visually recognized as a belt-like halo along the X-direction, as illustrated in  FIG. 20 . 
     Accordingly, the signal processor  10  of the first embodiment serves as a controller that increases, when adjacent two of the dimming areas LD differ in light transmittance from each other, the output gradation values of pixels that are in the vicinity of the boundary (such as within an area containing a predetermined number of pixels (x_pix) extending from the boundary) between the two adjacent dimming areas LD and located in one of the two dimming areas having lower light transmittance. This control can restrain the generation of the abrupt change line ST 1  of the output luminance. 
       FIG. 21  is a diagram illustrating an example of image data output to the image display panel  30  under the conditions of the light source luminance distribution illustrated in  FIG. 13  and the transmittance of the dimming panel  80  illustrated in  FIG. 18  in the first embodiment. As illustrated, for example, in  FIG. 21 , the signal processor  10  assumes one end of the display segment regions PA at (y 2 ) to be a pixel  48  located in a position (position P 1 ) closest to the boundary between the display segment regions PA at (y 1 ) and the display segment regions PA at (y 2 ), and sets, as target pixels, the pixels  48  located within the area containing the predetermined number of pixels (x_pix) extending from the one end side toward the other end side. The predetermined number of pixels (x_pix) is equal to or smaller than the number of pixels in the Y-direction included in a single display segment region PA. In the example illustrated in  FIG. 21 , the width in the Y-direction of each of the display segment regions PA at (y 2 ), that is, the number of pixels in the Y-direction included in one of the display segment regions PA is equal to the predetermined number of pixels (x_pix). However, this is a mere example. The predetermined number of pixels (x_pix) is not limited to this example. 
     The signal processor  10  sets the output gradation values of the target pixels closer to the boundary between the two of the dimming areas LD to higher values. Specifically, the signal processor  10  (refer to  FIG. 23 ) sets the gradation values of the pixel  48  located in the position P 1  among the target pixels to values corresponding a ratio (k) between the first contrast and the second contrast. Specifically, for example, k=BL_c/DP_c. For example, when BL_c=500, and DP_c=1000, k=0.5 (=50[%]). In this case, the signal processor  10  increases the gradation values of the pixel  48  in the position P 1  to gradation values that reduce the transmittance of the image display panel  30  to 50[%]. As a specific example, since the display output of the display segment regions PA at (y 2 ) is black for all the pixels  48  therein, the gradation values before being increased are (R,G,B)=(0,0,0). The signal processor  10  increases the gradation values of the pixel  48  in the position P 1  to gradation values corresponding to a gray of 50[%]. When the gradation values are 8-bit values, the gradation values of the gray of 50[%] are (R,G,B)=(127,127,127). The signal processor  10  corrects the gradation values of each of the target pixels other than the pixel  48  in the position P 1  to values higher than (R,G,B)=(0,0,0). Specifically, the signal processor  10  determines the degree of correction such that the corrected gradation values of the target pixels gradually decrease from the one end side toward the other end side. In  FIG. 21 , as indicated by a straight line L 1 , the corrected gradation values of the target pixels gradually linearly decrease from the one end side toward the other end side. This is, however, a mere example of the relation between the position in the Y-direction of each of the target pixels and the degree of correction of the gradation values. The relation between the position in the Y-direction of each of the target pixels and the degree of correction of the gradation values is not limited to this example, and may be represented by, for example, a quadratic or higher-order curve. 
       FIG. 22  is a magnified schematic diagram of the output luminance obtained when the dimming panel  80  having the transmittance illustrated in  FIG. 18  is interposed between the light source device having the light source luminance distribution illustrated in  FIG. 13  and the image display panel  30  having the transmittance illustrated in  FIG. 21 . Since the signal processor  10  increases the gradation values of the target pixels, the output luminance in the display segment regions PA at (y 2 ) gradually decreases from the one end side toward the other end side, as illustrated in  FIG. 22 . This can restrain the generation of the abrupt change line ST 1  of the output luminance described with reference to  FIGS. 19 and 20 . Consequently, the luminance difference caused by the difference in transmittance between the two adjacent dimming areas LD can be made less visible. Accordingly, the occurrence of the belt-like halo can be restrained, and improvement can be made in display quality and contrast perception resulting from the restraint of the black floating U. 
     Although  FIG. 22  illustrates the gradual reduction of the output luminance in the display segment regions PA at (y 2 ) with a straight line L 2 , the straight line L 2  merely illustrates the gradual reduction of the output luminance corresponding to the straight line L 1  illustrated in  FIG. 21 . The gradual reduction of the output luminance is not limited to the straight line L 2 . The gradual reduction pattern of the output luminance resulting from the correction of the gradation values of the target pixels is a pattern corresponding to the relation between the position in the Y-direction of each of the target pixels and the degree of correction of the gradation values. 
       FIG. 23  is a block diagram illustrating an exemplary functional configuration of the signal processor  10 . The signal processor  10  of the first embodiment is an integrated circuit, such as a field-programmable gate array (FPGA) and so on. As illustrated, for example, in  FIG. 23 , the signal processor  10  includes, for example, a required luminance information acquirer  101 , a dimming gradation calculator  102 , an image correction coefficient generator  103 , the lighting amount calculator  104 , a luminance distribution generator  105 , an inverse luminance generator  106 , and an image processor  107 . 
     The required luminance information acquirer  101  acquires the luminance of the light source  51  required for each of the display segment regions PA for performing the display output corresponding to the input signals IP. Specifically, the required luminance information acquirer  101  identifies the gradation value of the sub-pixel  49  set to have the maximum gradation value in each of the display segment regions PA. More specifically, the required luminance information acquirer  101  segments the gradation values of the respective sub-pixels  49  represented by the input signals IP for each of the display segment regions PA. The required luminance information acquirer  101  identifies the gradation value of the sub-pixel  49  set to have the maximum gradation value from among gradation values of the sub-pixels  49  included in a single display segment region PA. The required luminance information acquirer  101  identifies the luminance of the light source  51  required for obtaining output luminance corresponding to the gradation value of the sub-pixel  49  set to have the maximum gradation value in each of the display segment regions PA. For example, when the gradation value of the sub-pixel  49  is an 8-bit value (0 to 255), the luminance of the light source  51  required for obtaining the output luminance corresponding to a gradation value of 255 is 100[%]. The luminance of the light source  51  required for obtaining the output luminance corresponding to a gradation value of 0 is 0[%]. The required luminance information acquirer  101  performs the processing of identifying the luminance of the light source  51  as described above, for each of the display segment regions PA. The required luminance information acquirer  101  acquires information indicating the identified luminance of the light source  51  of each of the display segment regions PA as required luminance information. The required luminance is calculated taking account of attenuation in intensity of the light with the distance from the light source  51 . 
     The dimming gradation calculator  102  calculates the gradation value of each of the dimming areas LD. Specifically, the dimming gradation calculator  102  segments the display segment regions PA for each of the coordinates in the Y-direction (such as (y 1 ), (y 2 ), (y 3 ), and (y 4 )). The dimming gradation calculator  102  calculates the transmittance of the dimming area LD at (y 1 ) with reference to the required luminance information acquired by the required luminance information acquirer  101 . For example, if the required luminance of all the display segment regions PA having the coordinate at (y 1 ) in the Y-direction is 0[%], the dimming gradation calculator  102  of the first embodiment calculates the transmittance of the dimming area LD at (y 1 ) to be the minimum transmittance (BL_min), or if not, the dimming gradation calculator  102  of the first embodiment calculates the transmittance of the dimming area LD at (y 1 ) to be the maximum transmittance (BL_max). The dimming gradation calculator  102  calculates the gradation values such that a gradation value (such as 0) of the dimming area LD having the minimum transmittance (BL_min) is distinguishable from a gradation value (such as 1) of the dimming area LD having the maximum transmittance (BL_max). The dimming gradation calculator  102  also calculates the transmittance and the gradation values of the dimming areas LD at (y 2 ), (y 3 ), and (y 4 ) in the same manner as in the case of the dimming area LD at (y 1 ). The dimming gradation calculator  102  outputs signals including the information indicating the calculated gradation values of the dimming areas LD as the local dimming signals DI. 
     In the first embodiment, the dimming area LD is controlled to have the minimum transmittance (BL_min) according to the gradation value (such as 0) of the dimming area LD having the minimum transmittance (BL_min). The dimming area LD is controlled to have the maximum transmittance (BL_max) in accordance with the gradation value (such as 1) of the dimming area LD having the maximum transmittance (BL_max). 
     The image correction coefficient generator  103  calculates an image correction coefficient (kpix(v)) used for correction to increase the output gradation values of the target pixels. Specifically, if, for example, gradation values of adjacent two of the dimming areas LD among the gradation values of the dimming areas LD calculated by the dimming gradation calculator  102  differ from each other, the image correction coefficient generator  103  sets the target pixels in one of the dimming areas LD for which gradation values corresponding to lower transmittance have been calculated. The image correction coefficient generator  103  uses the scheme described with reference to  FIG. 21  to calculate correction values for correcting the output gradation values of the respective target pixels. The image correction coefficient generator  103  calculates the correction values for pixels other than the target pixels to be zero. The image correction coefficient generator  103  calculates the image correction coefficient (kpix(v)) in the form of a function (such as a linear function) associating the calculated correction value with arrangement of the pixels  48  aligning from one end side to the other end side (or from the other end side to the one end side) in the Y-direction. In the first embodiment, the image correction coefficient (kpix(v)) is sequentially read to obtain the correction values for the pixels  48  aligning from the one end side to the other end side in the Y-direction. As described above, the image correction coefficient (kpix(v)) includes the information associating the correction values with the positions of the target pixels for which the correction values for increasing the gradation values are set. Since the image correction coefficient (kpix(v)) gives a correction value of zero to the pixels  48  that are not the target pixels, the target pixels are limited to the pixels  48  to be increased in gradation values by the correction. 
     The lighting amount calculator  104  calculates the lighting amount of each of the light sources  51  based on the required luminance information. Specifically, as described with reference to  FIGS. 13 and 14 , the lighting amount calculator  104  calculates the lighting amount of each of the light sources  51  such that the required luminance on the other end side of each of the display segment regions PA is sufficiently obtained. Information indicating a relation between the lighting amounts of the light sources  51  and the luminance on the other end side of the display segment regions PA may be included, for example, in the reference data, or in data included in the lighting amount calculator  104  that is prepared separately from the reference data. The lighting amount calculator  104  outputs a signal including the information indicating the calculated lighting amount of each of the light sources  51  as the light source drive signal BL. 
     The luminance distribution generator  105  generates information indicating the luminance distribution obtained by the lighting amounts of the light sources  51  calculated by the lighting amount calculator  104 . Specifically, the luminance distribution generator  105  generates the information indicating the luminance distribution in the Y-direction in the positions of the pixels  48  arranged in the X-direction based on the lighting amount of each of the light sources  51  calculated by the lighting amount calculator  104 . More specifically, the luminance distribution generator  105  has data indicating, for example, a relation between the lighting amount of each of the light sources  51  and the luminance distribution that are measured in advance taking into account the influence of the light from the light sources  51 . With reference to the data, the luminance distribution generator  105  generates the information indicating the luminance distribution in the Y-direction (v) in the positions (h) of the pixels  48  arranged in the X-direction. In other words, the luminance of the light from the light source device  50  in the position of the pixel  48  at (h,v) can be identified from the information indicating the luminance distribution generated by the luminance distribution generator  105 . 
     Based on the luminance distribution generated by the luminance distribution generator  105 , the inverse luminance generator  106  generates the inverse of the luminance (inverse luminance gainpix(h,v)) corresponding to the position of the pixel  48  at (h,v). Specifically, the inverse luminance generator  106  performs, for example, processing of converting the luminance distribution represented in percentage [%] generated by the luminance distribution generator  105  into that represented in decimal number (processing of division by 100) and generates the inverse of the value represented in decimal number as the inverse luminance gainpix(h,v) corresponding to the position of the pixel  48  at (h,v). For example, in the case of the pixel  48  associated with luminance of 120[%] in the information indicating the luminance distribution, the inverse luminance gainpix(h,v) is approximately 0.83. In the case of the pixel  48  associated with luminance of 60[%] in the information indicating the luminance distribution, the inverse luminance gainpix(h,v) is approximately 1.67. 
     The image processor  107  calculates the output gradation values of the pixels  48  serving as the output image signals OP based on the gradation values of the pixel  48  included in the input signals IP, the inverse luminance gainpix(h,v) generated by the inverse luminance generator  106 , and the image correction coefficient (kpix(v)) calculated by the image correction coefficient generator  103 . Specifically, the image processor  107  multiplies the gradation values of the pixels  48  included in the input signals IP by the gain. More specifically, the image processor  107  multiplies the gradation value of each of R, G, and B included in the gradation values of the pixel  48  at (h,v) by the inverse luminance gainpix(h,v). This multiplication applies the gain to the gradation value of each of R, G, and B. However, the gradation values of black (R,G,B)=(0,0,0) obtain no gain. The image processor  107  may omit the application of the gain to the gradation values of black (R,G,B)=(0,0,0). The image processor  107  adds the image correction coefficient (kpix(v)) to the gradation values of black among the gradation values of the pixels  48  included in the input signals IP. More specifically, the image processor  107  adds the image correction coefficient (kpix(v)) to the gradation value of each of R, G, and B included in the gradation values of the pixel  48  at (v) in which (R,G,B)=(0,0,0). This calculation can increase the gradation values of the target pixel among the pixels  48  at (v) in which (R,G,B)=(0,0,0). The image processor  107  outputs the output image signals OP. 
       FIG. 24  is a flowchart of processing by the signal processor  10 . The signal processor  10  performs the acquisition of the required luminance information (Step S 1 ), the calculation of the transmittance of the dimming areas LD (Step S 2 ), the generation of the image correction coefficient (Step S 3 ), the calculation of the lighting amounts (Step S 4 ), the generation of the inverse of the luminance (Step S 5 ), and the calculation of the output gradation values (Step S 6 ). Of the processes from Step S 1  to Step S 6 , the processes from Step S 2  to Step S 3  and the processes from Step S 4  to Step S 5  may be performed in parallel after the process at Step S 1 . The process at Step S 6  is performed after the processes at Step S 3  and Step S 5 . 
       FIG. 25  is a diagram schematically illustrating an example of processing details of Step S 1  to Step S 5  in the flowchart illustrated in  FIG. 24 . During the acquisition of the required luminance information (Step S 1 ), the required luminance information acquirer  101  acquires the luminance of each of the light sources  51  required for the display segment regions PA.  FIG. 25  illustrates a case where, at Step S 1 , the required luminance levels of the display segment regions PA at (x 1 ,y 1 ), (x 1 ,y 3 ), (x 3 ,y 1 ), and (x 3 ,y 3 ) are 40 [%], 10 [%], 100 [%], and 20[%], respectively, and the required luminance levels of the display segment regions PA of the other positions are 0[%]. 
     During the calculation of the transmittance of the dimming areas LD (Step S 2 ), the dimming gradation calculator  102  calculates the transmittance of the dimming areas LD and the gradation values corresponding to the transmittance.  FIG. 25  illustrates a case where, at Step S 2 , the transmittance of the dimming areas LD at (y 1 ) and (y 3 ) is the maximum transmittance (BL_max) (expressed as 100[%] in  FIG. 25 ), and the transmittance of the dimming areas LD at (y 2 ) and (y 4 ) is the minimum transmittance (BL_min) (expressed as 0[%] in  FIG. 25 ). 
     During the generation of the image correction coefficient (Step S 3 ), the image correction coefficient generator  103  calculates the image correction coefficient (kpix(v)).  FIG. 25  illustrates an example in which, at Step S 3 , the target pixels are set in the display segment regions PA at (y 2 ) and (y 4 ), and the correction values for increasing the gradation values are calculated for the case where the gradation values of the target pixels are (R,G,B)=(0,0,0). More specifically, in  FIG. 25 , assume that, among the pixels  48  included in the display segment regions PA at (y 2 ), a pixel  48  located in a position closest to the boundary between the display segment regions PA at (y 1 ) and the display segment regions PA at (y 2 ) serves as one end, and a pixel  48  located in a position closest to the boundary between the display segment regions PA at (y 2 ) and the display segment regions PA at (y 3 ) serves as the other end. In this case, the pixels  48  located within the area containing the predetermined number of pixels (x_pix) extending from the one end side toward the other end side are set as the target pixels. In addition, the pixels  48  located within the area containing the predetermined number of pixels (x_pix) extending from the other end side toward the one end side are set as the target pixels. In this manner, the predetermined number of pixels (x_pix) may be determined in consideration of the case where the pixels  48  located within the areas containing the predetermined number of pixels (x_pix) extending from the one end side and the other end side in one of the display segment regions PA are set as the target pixels. For example, the predetermined number of pixels (x_pix) may be equal to or smaller than half the number of pixels in the Y-direction included in one of the display segment regions PA. In  FIG. 25 , assuming that, among the pixels  48  included in the display segment regions PA at (y 4 ), a pixel  48  located in a position closest to the boundary between the display segment regions PA at (y 3 ) and the display segment regions PA at (y 4 ) serves as one end, the pixels  48  located within the area containing the predetermined number of pixels (x_pix) extending from the one end side toward the other end side are set as the target pixels. 
     During the calculation of the lighting amounts (Step S 4 ), the lighting amount calculator  104  calculates the lighting amounts of the respective light sources  51 .  FIG. 25  illustrates a case where, at Step S 4 , the lighting amounts are calculated such that the light sources  51  at (x 1 ) and (x 3 ) are lit up at lighting amounts capable of obtaining luminance of 42[%] and 120[%], respectively, on one end side of the display segment regions PA at (y 1 ). 
     During the generation of the inverse of the luminance (Step S 5 ), the luminance distribution generator  105  generates the information indicating the luminance distribution obtained by the lighting amounts of the light sources  51  calculated by the lighting amount calculator  104 . Then, the inverse luminance generator  106  generates the inverse luminance gainpix(h,v) corresponding to the position of the pixel  48  at (h,v) based on the luminance distribution generated by the luminance distribution generator  105 .  FIG. 25  illustrates the luminance distribution and the inverse luminance gainpix(h,v) that are generated at Step S 5  corresponding to the light source  51  at (x 3 ). 
       FIG. 26  is a flowchart of the calculation processing of the output gradation values in  FIG. 24 . During the calculation of the output gradation values (Step S 6 ), the image processor  107  calculates the output gradation values of the pixels  48  serving as the output image signals OP. Specifically, the image processor  107  determines whether the gradation values of one of the pixels  48  included in the input signals IP are (R,G,B)=(0,0,0) (Step S 61 ). More specifically, as illustrated, for example, in Step S 61 , the image processor  107  checks whether the gradation value is zero for each of the sub-pixels  49  included in the one of the pixels  48 . In other words, the image processor  107  individually checks whether a gradation value (Rin(h,v)) of the first sub-pixel  49 R, a gradation value (Gin(h,v)) of the second sub-pixel  49 G, and a gradation value (Bin(h,v)) of the third sub-pixel  49 B included in the input signals IP are zero. 
     If the gradation values of one of the target pixels included in the input signals IP are (R,G,B)=(0,0,0) (Yes at Steps S 61 ), the image processor  107  adds the image correction coefficient (kpix (v)) to the gradation value of each of the sub-pixels  49  included in one of the pixels  48  determined to be the target pixels (Step S 62 ). Specifically, the image processor  107  adds the image correction coefficient (kpix (v)) to each of the gradation value (Rin(h,v)) of the first sub-pixel  49 R, the gradation value (Gin(h,v)) of the second sub-pixel  49 G, and the gradation value (Bin(h,v)) of the third sub-pixel  49 B included in the input signals IP. Thus, the image processor  107  calculates a gradation value (Rout(h,v)) of the first sub-pixel  49 R, a gradation value (Gout(h,v)) of the second sub-pixel  49 G, and a gradation value (Bout(h,v)) of the third sub-pixel  49 B that serve as the output image signals OP. 
     If the gradation values of the one of the target pixels  48  included in the input signals IP are not (R,G,B)=(0,0,0) (No at Steps S 61 ), the image processor  107  multiplies the gradation value of each of the sub-pixels  49  included in the one of the pixels  48  having been subjected to the determination by the inverse luminance gainpix(h,v) (Step S 63 ). Specifically, the image processor  107  multiplies each of the gradation value (Rin(h,v)) of the first sub-pixel  49 R, the gradation value (Gin(h,v)) of the second sub-pixel  49 G, and the gradation value (Bin(h,v)) of the third sub-pixel  49 B included in the input signals IP by the inverse luminance gainpix(h,v). Thus, the image processor  107  calculates the gradation value (Rout(h,v)) of the first sub-pixel  49 R, the gradation value (Gout(h,v)) of the second sub-pixel  49 G, and the gradation value (Bout(h,v)) of the third sub-pixel  49 B that serve as the output image signals OP. 
     As described above, according to the first embodiment, when adjacent two of the dimming areas LD differ in light transmittance from each other, the pixels  48  located close to the boundary between the two dimming areas LD are selected as the target pixels from among pixels located in one of the dimming areas LD having lower light transmittance, and the output gradation values of the target pixels are increased. As a result, the occurrence of the belt-like halo can be restrained, and the improvement can be made in display quality and contrast perception resulting from the restraint of the black floating U. 
     The output gradation values of the target pixels closer to the boundary between the two dimming areas LD are set higher. This setting facilitates the gradual reduction of the output luminance of the display device  1  with the distance from the vicinity of the boundary between the two dimming areas LD. Accordingly, the occurrence of the belt-like halo can be restrained in a more reliable manner. 
     Modification 
     The following describes a modification of the first embodiment with reference to  FIGS. 27 to 30 . In the description of the modification, the same reference numerals will be assigned to the same components as those of the first embodiment described with reference to  FIGS. 1 to 26 , and description thereof will not be made in some cases. 
       FIG. 27  is a block diagram illustrating another exemplary functional configuration of a signal processor  10 A in the modification. The display device according to the modification includes the signal processor  10 A as a component instead of the signal processor  10  of the first embodiment. The signal processor  10 A of the modification includes a required luminance correction coefficient generator  111 , a required luminance corrector  112 , and an inverse luminance corrector  113 , in addition to the components of the signal processor  10  of the first embodiment. The signal processor  10 A of the modification also includes a dimming gradation calculator  102 A, an image correction coefficient generator  103 A, and an image processor  107 A, instead of the dimming gradation calculator  102 , the image correction coefficient generator  103 , and the image processor  107  of the first embodiment. 
     The dimming gradation calculator  102 A of the modification calculates the transmittance of the dimming area LD at (y 1 ) with reference to the required luminance information acquired by the required luminance information acquirer  101 . For example, if the required luminance of all the display segment regions PA having the coordinate at (y 1 ) in the Y-direction is 0[%], the dimming gradation calculator  102 A calculates the transmittance of the dimming area LD at (y 1 ) to be the minimum transmittance (BL_min). If the maximum required luminance of the required luminance of the display segment regions PA having the coordinate at (y 1 ) in the Y-direction exceeds 0[%] and is equal to or less than 25[%], the dimming gradation calculator  102 A sets the transmittance of the dimming area LD at (y 1 ) to be first intermediate transmittance. The dimming gradation calculator  102 A calculates the first intermediate transmittance to be, for example, 25[%]. If the maximum required luminance of the required luminance of the display segment regions PA at (y 1 ) exceeds 25[%] and is equal to or less than 50[%], the dimming gradation calculator  102 A sets the transmittance of the dimming area LD at (y 1 ) to be second intermediate transmittance. The dimming gradation calculator  102 A calculates the second intermediate transmittance to be, for example, 50[%]. If neither of the above described conditions is met, the dimming gradation calculator  102 A calculates the transmittance of the dimming area LD at (y 1 ) to be the maximum transmittance (BL_max). The dimming gradation calculator  102 A calculates the gradation values such that the gradation value (such as 0) of the dimming area LD having the minimum transmittance (BL_min), the gradation value (such as 1) of the dimming area LD having the first intermediate transmittance, the gradation value (such as 2) of the dimming area LD having the second intermediate transmittance, and the gradation value (such as 3) of the dimming area LD having the maximum transmittance (BL_max) are distinguishable from one another. The dimming gradation calculator  102 A also calculates the transmittance and the gradation values of the dimming areas LD at (y 2 ), (y 3 ), and (y 4 ) in the same manner as in the case of the dimming area LD at (y 1 ). The dimming gradation calculator  102 A outputs signals including the information indicating the calculated gradation values of the dimming areas LD as the local dimming signals DI in the modification. 
     In the modification, the dimming area LD is controlled to have the minimum transmittance (BL_min) according to the gradation value (such as 0) of the dimming area LD having the minimum transmittance (BL_min). The dimming area LD is controlled to have the transmittance of 25[%] in accordance with the gradation value (such as 1) of the dimming area LD having the first intermediate transmittance. The dimming area LD is controlled to have the transmittance of 50[%] in accordance with the gradation value (such as 2) of the dimming area LD having the second intermediate transmittance. The dimming area LD is controlled to have the maximum transmittance (BL_max) in accordance with the gradation value (such as 3) of the dimming area LD having the maximum transmittance (BL_max). In this manner, the dimming areas LD of the modification are capable of changing the light transmittance to the minimum transmittance (BL_min), to the maximum transmittance (BL_max), or to any of one or more degrees of intermediate transmittance serving as transmittance between the minimum transmittance (BL_min) and the maximum transmittance (BL_max). The intermediate transmittance may be of one degree or three or more degrees, or may be set to any transmittance between 0% and 100%. 
     The required luminance correction coefficient generator  111  generates a required luminance correction coefficient based on the gradation values calculated by the dimming gradation calculator  102 A. The required luminance correction coefficient is a coefficient for correcting the required luminance indicated by the required luminance information acquired by the required luminance information acquirer  101 . Specifically, if the dimming value has, for example, four gradations, the required luminance correction coefficient generator  111  sets the required luminance correction coefficient of the dimming area LD having a gradation value of 0 or 3 to 1.0. In other words, the required luminance correction coefficient generator  111  sets the required luminance correction coefficient of the dimming area LD having the minimum transmittance (BL_min) or the maximum transmittance (BL_max) to 1.0. The required luminance correction coefficient generator  111  sets the required luminance correction coefficient of the dimming area LD having a gradation value of 1 to 4.0. In other words, the required luminance correction coefficient generator  111  sets the required luminance correction coefficient of the dimming area LD having the transmittance of 25[%] to 4.0. The required luminance correction coefficient generator  111  sets the required luminance correction coefficient of the dimming area LD having a gradation value of 2 to 2.0. In other words, the required luminance correction coefficient generator  111  sets the required luminance correction coefficient of the dimming area LD having the transmittance of 50[%] to 2.0. 
     The required luminance corrector  112  corrects the required luminance information acquired by the required luminance information acquirer  101  based on the required luminance correction coefficient generated by the required luminance correction coefficient generator  111 . Specifically, the required luminance corrector  112  multiplies the required luminance of each of the display segment regions PA by the required luminance correction coefficient of the dimming area LD located at corresponding coordinates in the Y-direction. The lighting amount calculator  104  of the modification calculates the lighting amount of each of the light sources  51  based on the required luminance information corrected by the required luminance corrector  112 . 
     If the light transmittance in one of the two adjacent dimming areas LD having lower light transmittance is the minimum transmittance (BL_min), the image correction coefficient generator  103 A of the modification causes the output gradation values of the target pixels to be higher than those in the case where the lower light transmittance is not the minimum transmittance. Specifically, if the light transmittance in one of the two adjacent dimming areas LD having lower light transmittance is the minimum transmittance (BL_min), the image correction coefficient generator  103 A performs the same processing as that performed by the image correction coefficient generator  103  described with reference to  FIG. 21 . Specifically, the image correction coefficient generator  103 A sets the gradation values of the pixel  48  located in the position P 1  among the target pixels to values corresponding the ratio (k) between the first contrast and the second contrast (for example, k=0.5 (=50[%])). 
     If the light transmittance in one of the two adjacent dimming areas LD having lower light transmittance is not the minimum transmittance (BL_min), the image correction coefficient generator  103 A calculates a correction value (ka) for the gradation values of the pixel  48  located in the position P 1  based on Expression (1) below. In Expression (1), B(PY) denotes the luminance (in [%]) at the boundary between the two adjacent dimming areas LD provided by the light source  51 ; BL_high denotes the light transmittance (in [%]) in one of the two adjacent dimming areas LD having higher light transmittance; and BL_low denotes the light transmittance (in [%]) in one of the two adjacent dimming areas LD having lower light transmittance.
 
 ka =( B ( PY )/ DP _con)×( BP _con/ DP _con)/( BL _high/ BL _low)  (1)
 
     For example, if B(PY)=120[%], DP_con=1000, BP_con=500, BL_high=100[%], and BL_low=25[%], then ka=0.24[%]. The values of and the relation between the various values in Expression (1) are such that ka is always lower than the ratio (k) between the first contrast and the second contrast. 
     In the same manner as the image correction coefficient generator  103 , the image correction coefficient generator  103 A determines the degree of correction on a pixel by pixel basis such that the corrected gradation values of each of the target pixels gradually decrease from the one end side toward the other end side (from the other end side toward the one end side if the position P 1  lies on the other end side). The image correction coefficient generator  103 A calculates the calculated correction value as the image correction coefficient (kpix(h,v)). In the modification, the luminance (in [%]) at the boundary between the two adjacent dimming areas LD that is provided by the light source  51  can change with the position in the X-direction, and thus the coordinate management of the image correction coefficient is performed in the X-direction. In other words, in the modification, the image correction coefficient specific to each of the pixels  48  is calculated with respect to not only the Y-direction but also the X-direction. 
     Based on the required luminance correction coefficient generated by the required luminance correction coefficient generator  111 , the inverse luminance corrector  113  corrects the inverse luminance gainpix(h,v) generated by the inverse luminance generator  106 . Specifically, the inverse luminance corrector  113  multiplies the inverse luminance gainpix(h,v) by the required luminance correction coefficient of the dimming area LD located at corresponding coordinates in the Y-direction. The inverse luminance corrector  113  outputs the corrected inverse luminance gainpix(h,v) as inverse luminance Egainpix(h,v). 
     The image processor  107 A of the modification uses the inverse luminance Egainpix(h,v) corrected by the inverse luminance corrector  113 , and multiplies the gradation values of the pixels  48  included in the input signals IP by the gain, and then adds the image correction coefficient (kpix(h,v)) to each of the results regardless of whether the gradation values of the pixels  48  included in the input signals IP are gradation values corresponding to black. The configuration of the image processor  107 A of the modification is the same as that of the image processor  107  of the first embodiment except in the processing on the gradation values of the pixels  48  included in the input signals IP. 
       FIG. 28  is a flowchart of processing by the signal processor  10 A of the modification. The signal processor  10 A performs the acquisition of the required luminance information (Step S 11 ), the calculation of the transmittance of the dimming areas LD (Step S 12 ), the generation of the required luminance correction coefficients (Step S 13 ), the correction of the required luminance (Step S 14 ), the calculation of the lighting amounts (Step S 15 ), the generation of the inverse of the luminance (Step S 16 ), the correction of the inverse of the luminance (Step S 17 ), the generation of the image correction coefficients (Step S 18 ), and the calculation of the output gradation values (Step S 19 ). 
       FIG. 29  is a diagram schematically illustrating an example of processing details performed at Step S 11  to Step S 15  in the flowchart illustrated in  FIG. 28 . During the acquisition of the required luminance information (Step S 11 ), the required luminance information acquirer  101  acquires the luminance of the light source  51  required for each of the display segment regions PA.  FIG. 29  illustrates a case where, at Step S 11 , the required luminance levels of the display segment regions PA at (x 1 ,y 1 ), (x 1 ,y 3 ), (x 3 ,y 1 ), (x 3 ,y 2 ), and (x 3 ,y 3 ) are 40[%], 10[%], 100[%], 20[%], and 40[%], respectively, and the required luminance of the display segment regions PA of the other positions is 0[%]. 
     During the calculation of the transmittance of the dimming areas (Step S 12 ), the dimming gradation calculator  102 A calculates the transmittance of the dimming areas LD and the gradation values corresponding to the transmittance.  FIG. 29  illustrates a case where, at Step S 12 , the transmittance of the dimming area LD at (y 1 ) is the maximum transmittance (BL_max) (expressed as 100[%] in  FIG. 29 ), the transmittance of the dimming area LD at (y 2 ) is the first intermediate transmittance (25 [%]), the transmittance of the dimming area LD at (y 3 ) is the second intermediate transmittance (50[%]), and the transmittance of the dimming area LD at (y 4 ) is the minimum transmittance (BL_min) (expressed as 0[%] in  FIG. 29 ). 
     During the generation of the required luminance correction coefficients (Step S 13 ), the required luminance correction coefficient generator  111  generates the required luminance correction coefficients.  FIG. 29  illustrates a case where, at Step S 13 , the required luminance correction coefficients of the dimming areas LD at (y 1 ) and (y 4 ) are 1.0, the required luminance correction coefficient of the dimming area LD at (y 2 ) is 4.0, and the required luminance correction coefficient of the dimming area LD at (y 3 ) is 2.0. 
     During the correction of the required luminance (Step S 14 ), the required luminance corrector  112  corrects the required luminance information based on the required luminance correction coefficients. In  FIG. 29 , at Step S 14 , the required luminance (10[%] and 40[%]) of the display segment regions PA at (x 1 ,y 3 ) and (x 3 ,y 3 ) is multiplied by the required luminance correction coefficient (2.0) of the dimming area LD at (y 3 ), and as a result, the required luminance levels of the display segment regions PA at (x 1 ,y 3 ) and (x 3 ,y 3 ) are corrected to 20 [%] and 80[%], respectively. In addition, the required luminance (20[%]) of the display segment region PA at (x 3 ,y 2 ) is multiplied by the required luminance correction coefficient (4.0) of the dimming area LD at (y 2 ), and as a result, the required luminance level of the display segment region PA at (x 3 ,y 2 ) is corrected to 80[%]. 
     During the calculation of the lighting amounts (Step S 15 ), the lighting amount calculator  104  of the modification calculates the lighting amounts of the respective light sources  51 .  FIG. 29  illustrates a case where, at Step S 15 , the lighting amounts are calculated such that the light sources  51  at (x 1 ) and (x 3 ) are lit up at lighting amounts capable of obtaining luminance of 48 [%] and 140[%], respectively, on one end side of the display segment regions PA at (y 1 ). 
       FIG. 30  is a diagram schematically illustrating an example of processing details performed at Step S 16  to Step S 18  in the flowchart illustrated in  FIG. 28 . During the generation of the inverse of the luminance (Step S 16 ), the luminance distribution generator  105  generates the information indicating the luminance distribution based on the lighting amounts of the light sources  51  calculated by the lighting amount calculator  104 . Then, the inverse luminance generator  106  generates the inverse luminance gainpix(h,v) corresponding to the position of the pixel  48  at (h,v) based on the luminance distribution generated by the luminance distribution generator  105 .  FIG. 30  illustrates the luminance distribution and the inverse luminance gainpix(h,v) that are generated at Step S 16  corresponding to the light source  51  at (x 3 ). The luminance distribution corresponding to the light source  51  at (x 3 ) represents luminance P 3  in the boundary position between the display segment regions PA at (y 1 ) and the display segment regions PA at (y 2 ) provided by the light source  51 , luminance P 4  in the boundary position between the display segment regions PA at (y 2 ) and the display segment regions PA at (y 3 ) provided by the light source  51 , and luminance P 5  in the boundary position between the display segment regions PA at (y 3 ) and the display segment regions PA at (y 4 ) provided by the light source  51 . Of these values of the luminance, the luminance P 5  corresponds to the required luminance (80[%]) of the display segment region PA at (x 3 ,y 3 ). 
     During the correction of the inverse of the luminance (Step S 17 ), the inverse luminance corrector  113  corrects the inverse luminance gainpix(h,v).  FIG. 30  illustrates, in Step S 17 , the correction of the inverse values of the luminance corresponding to the light source  51  at (x 3 ). Specifically, the inverse luminance gainpix(h,v) at (y 2 ) is multiplied by the required luminance correction coefficient (4.0) of the dimming area LD at (y 2 ), and the inverse luminance gainpix(h,v) at (y 3 ) is multiplied by the required luminance correction coefficient (2.0) of the dimming area LD at (y 3 ). The inverse luminance corrector  113  outputs the corrected inverse luminance gainpix(h,v) as the inverse luminance Egainpix(h,v). 
     During the generation of the image correction coefficients (Step S 18 ), the image correction coefficient generator  103 A calculates the image correction coefficients (kpix(h,v)).  FIG. 30  illustrates, in Step S 18 , the image correction coefficients (kpix(h,v)) at a coordinate (h) in the X-direction corresponding to the light source  51  at (x 3 ). The graph of the image correction coefficients (kpix(h,v)) illustrates an example in which the target pixels are set in the display segment regions PA at (y 2 ) and (y 4 ), and the correction values for increasing the gradation values are calculated. More specifically, in  FIG. 30 , assuming that, among the pixels  48  included in the display segment regions PA at (y 2 ), a pixel  48  located in a position closest to the boundary between the display segment regions PA at (y 1 ) and the display segment regions PA at (y 2 ) serves as one end, the pixels  48  located within the area containing the predetermined number of pixels (x_pix) extending from the one end side toward the other end side are selected as the target pixels. In addition, assuming that, among the pixels  48  included in the display segment regions PA at (y 2 ), a pixel  48  located in a position closest to the boundary between the display segment regions PA at (y 2 ) and the display segment regions PA at (y 3 ) serves as the other end, pixels  48  located within the area containing the predetermined number of pixels (x_pix) extending from the other end side toward the one end side are selected as the target pixels. Furthermore, assuming that, among the pixels  48  included in the display segment regions PA at (y 4 ), a pixel  48  located in a position closest to the boundary between the display segment regions PA at (y 3 ) and the display segment regions PA at (y 4 ) serves as one end, the pixels  48  located within the area containing the predetermined number of pixels (x_pix) extending from the one end side toward the other end side are selected as the target pixels. Values k 1  and k 2  in the graph of the image correction coefficients (kpix(h,v)) are examples of specific values of ka calculated by Expression (1) above. The value k 1  is a value of ka (0.24[%]) when B (P 3 )=120 [%], DP_con=1000, BP_con=500, BL_high=100[%], and BL_low=25[%]. The value k 2  is a value of ka (0.10[%]) when B (P 3 )=100[%], DP_con=1000, BP_con=500, BL_high=50[%], and BL_low=25[%]. 
     During the calculation of the output gradation values (Step S 19 ), the image processor  107 A of the modification uses the inverse luminance Egainpix(h,v), and multiplies the gradation values of the pixels  48  included in the input signals IP by the gain, and then adds the image correction coefficient (kpix(h,v)) to each of the results. Specifically, as illustrated, for example, in  FIG. 28 , the image processor  107 A of the modification calculates the gradation value (Rout(h,v)) of the first sub-pixel  49 R, the gradation value (Gout(h,v)) of the second sub-pixel  49 G, and the gradation value (Bout(h,v)) of the third sub-pixel  49 B that serve as the output image signals OP, as given by Expressions (2), (3), and (4) given below.
 
 R out( h,v )= E gainpix( h,v )× R in( h,v )+ k pix( h,v )  (2)
 
 G out( h,v )= E gainpix( h,v )× G in( h,v )+ k pix( h,v )  (3)
 
 B out( h,v )= E gainpix( h,v )× B in( h,v )+ k pix( h,v )  (4)
 
     As described above, according to the modification, the occurrence of the belt-like halo can be restrained in a more reliable manner even when the intermediate transmittance is included as the transmittance of the dimming areas LD. 
     Second Embodiment 
       FIG. 31  is a diagram illustrating an example of a light source device  50 A according to a second embodiment of the present invention. The light source device  50 A of the second embodiment serves as an illuminator having a plurality of light-emitting regions arranged in two intersecting directions. Specifically, as illustrated, for example, in  FIG. 31 , the light source device  50 A of the second embodiment includes a plurality of light sources  51 A arranged in the X-direction and the Y-direction. 
     The explanation of the second embodiment illustrates, in  FIG. 31  and other figures, a case where the coordinates in the Y-direction is managed based on five coordinates of y 1 , y 2 , . . . , and y 5 . However, this is a mere example, and the present invention is not limited thereto. The explanation of the second embodiment also illustrates a case where the coordinate in the X-direction is managed based on the nine coordinates of x 1 , x 2 , . . . , and x 9 , in the same manner as the explanation of the first embodiment. However, this is a mere example, and the present invention is not limited thereto. The number of coordinates can be changed as appropriate in both the first and second embodiments. 
     The light source device  50 A includes a light guide plate LAA that is sectioned by grooves or the like so as to guide the light of the light sources  51 A provided for each of coordinate positions ((x 1 ,y 1 ), (x 2 ,y 1 ), . . . , (x 8 ,y 5 ), and (x 9 ,y 5 )) of the display segment regions PA in the second embodiment on a coordinate position-by-coordinate position basis. This is a mere configuration example for providing the light-emitting regions arranged in the two intersecting directions. The configuration is not limited to this example. For example, light guide plates may be individually provided one for these coordinate positions each. 
       FIGS. 32 and 33  are diagrams illustrating another exemplary light source device of the second embodiment. As illustrated in  FIGS. 32 and 33 , a light source device  50 B may include guide portions (such as the light guide plates G 1 , G 2 , G 3 , G 4 , and G 5 ) and a plurality of emission portions (such as emission portions G 1   b , G 2   b , G 3   b , G 4   b , and G 5   b  of the light guide plates G 1 , G 2 , G 3 , G 4 , and G 5 ). The emission portions are arranged in the two intersecting directions, and the guide portions guide the light to the respective emission portions. The light guide plate G 1  is provided with a surface on the emission portion G 1   b  side of a bottom surface portion G 1   a , and a side surface portion separating the emission portions adjacent to each other at a location of the boundary LDL. The light guide plate G 1  guides the light of a light source  51 B provided at one end of the light guide plate G 1  to (y 1 ) by reflecting the light on the surface on the emission portion G 1   b  side and on the side surface portion and by letting the light go out from the emission portion G 1   b . The light guide plate G 2  is provided with a back surface of the bottom surface portion G 1   a  of the light guide plate G 1 , a surface on the emission portion G 2   b  side of a bottom surface portion G 2   a , and a side surface portion separating the emission portions adjacent to each other at the location of the boundary LDL. The light guide plate G 2  guides the light of the light source  51 B provided at one end of the light guide plate G 2  to (y 2 ) by reflecting the light on the back surface, on the surface on the emission portion G 2   b  side, and on the side surface portion and by letting the light go out from the emission portion G 2   b . The light guide plate G 3  is provided with a back surface of the bottom surface portion G 2   a  of the light guide plate G 2 , a surface on the emission portion G 3   b  side of a bottom surface portion G 3   a , and a side surface portion separating the emission portions adjacent to each other at the location of the boundary LDL. The light guide plate G 3  guides the light of the light source  51 B provided at one end of the light guide plate G 3  to (y 3 ) by reflecting the light on the back surface, on the surface on the emission portion G 3   b  side, and on the side surface and by letting the light go out from the emission portion G 3   b . The light guide plate G 4  is provided with a back surface of the bottom surface portion G 3   a  of the light guide plate G 3 , a surface on the emission portion G 4   b  side of a bottom surface portion G 4   a , and a side surface portion separating the emission portions adjacent to each other at the location of the boundary LDL. The light guide plate G 4  guides the light of the light source  51 B provided at one end of the light guide plate G 4  to (y 4 ) by reflecting the light on the back surface, on the surface on the emission portion G 4   b  side, and on the side surface portion and by letting the light go out from the emission portion G 4   b . The light guide plate G 5  is provided with a back surface of the bottom surface portion G 4   a  of the light guide plate G 4 , a surface on the emission portion G 5   b  side of a bottom surface portion G 5   a , a side surface portion separating the emission portions adjacent to each other at the location of the boundary LDL, and a side surface portion of another end LDW of the light guide plate G 5 . The light guide plate G 5  guides the light of the light source  51 B provided at one end of the light guide plate G 5  to (y 5 ) by reflecting the light on the back surface, on the surface on the emission portion G 5   b  side, and on the side surface portions and by letting the light go out from the emission portion G 5   b . As described above, the light guide plates G 1 , G 2 , G 3 , G 4 , and G 5  irradiate the display segment regions PA at the corresponding coordinates with light. 
     As illustrated in  FIG. 33 , the light guide plates G 1 , G 2 , G 3 , G 4 , and G 5  are individually provided corresponding to y 1 , y 2 , . . . , and y 5 . The light source  51 B is provided on one end side in the Y-direction of each of the light guide plates G 1 , G 2 , G 3 , G 4 , and G 5 . In other words, the light source device  50 B includes the light sources  51 B configured to emit light to be individually guided to (x 1 ,y 1 ), (x 2 ,y 1 ), . . . , (x 8 ,y 5 ), and (x 9 ,y 5 ). Among the light guide plates G 1 , G 2 , G 3 , G 4 , and G 5 , light guide plates located at both ends in the X-direction (such as at coordinates of x 1  and x 9 ) reflect light on one side surfaces LDS 1  and LDS 2  in the X-direction thereof. 
     As described above, each of the light source devices  50 A and  50 B of the second embodiment is provided with one or more light sources at each of a plurality of light guide regions. Specifically, either of the light sources  51 A and  51 B are individually provided at (x 1 ,y 1 ), (x 2 ,y 1 ), . . . , (x 8 ,y 5 ), and (x 9 ,y 5 ). In the examples described with reference to  FIGS. 31, 32, and 33 , each of the light guide regions corresponding to (x 1 ,y 1 ), (x 2 ,y 1 ), . . . , (x 8 ,y 5 ), and (x 9 ,y 5 ) is provided with one light source  51 A or one light source  51 B. However, each of the light guide regions may be provided with two or more light sources. 
       FIG. 34  is a diagram illustrating an exemplary main configuration of a dimmer  70 B according to the second embodiment. A dimming panel  80 B of the second embodiment has a plurality of dimming areas LDB arranged in the two intersecting directions. Specifically, the dimming panel  80 B is capable of individually adjusting the light transmittance at (x 1 ,y 1 ), (x 2 ,y 1 ), . . . , (x 8 ,y 5 ), and (x 9 ,y 5 ). As illustrated, for example, in  FIG. 34 , the dimming panel  80 B includes first electrodes  81 B individually provided at (x 1 ,y 1 ), (x 2 ,y 1 ), . . . , (x 8 ,y 5 ), and (x 9 ,y 5 ). That is, in the example illustrated in  FIG. 34 , the dimming areas LDB are provided with the individual first electrodes  81 B. 
     The circuitry  90  of the second embodiment individually controls the potentials of the first electrodes  81 B at different coordinate positions. The signal processor  10  of the second embodiment outputs the local dimming signals DI for individually controlling the light transmittance in the respective coordinate positions at (x 1 ,y 1 ), (x 2 ,y 1 ), . . . , (x 8 ,y 5 ), and (x 9 ,y 5 ) on a coordinate position-by-coordinate position basis. 
       FIG. 35  is a schematic diagram illustrating an example of display output.  FIG. 35  and  FIGS. 36 and 37  to be explained later illustrate the boundary lines LDL between the adjacent dimming areas LDB in order to clearly indicate the relation with the dimming areas. For example, as illustrated in  FIG. 35 , assume a case of requiring a display output in which one of the display segment regions PA includes a high luminance portion LP 1  that requires light from the light source and the other of the display segment regions PA require the minimum luminance (black). 
       FIG. 36  is a schematic diagram illustrating an exemplary light source luminance distribution corresponding to the display output illustrated in  FIG. 35 . The light source device (such as the light source device  50 A or the light source device  50 B) of the second embodiment emits light from the light guide region at the same coordinates as those of the display segment region PA including the high luminance portion LP 1 . The light source device does not emit light from the other light guide regions. However, a part of the light from the light guide region at the same coordinates as those of the display segment region PA including the high luminance portion LP 1  can reach the surrounding display segment regions PA adjacent to the display segment region PA. This phenomenon generates a light source luminance distribution LP 2  centered on the display segment region PA including the high luminance portion LP 1 . If a display device not including the dimmer  70 B is assumed, the black floating U occurs in the area of the light source luminance distribution LP 2  through the same mechanism as that described with reference to  FIG. 16 . 
       FIG. 37  is a schematic diagram illustrating a case where abrupt change lines ST 2 , ST 3 , ST 4 , and ST 5  of the output luminance are generated in the light source luminance distribution illustrated in  FIG. 36 . The display segment regions PA other than the display segment region PA including the high luminance portion LP 1  do not need light. Accordingly, if the dimming panel  80 B is operated such that the dimming areas LDB at the same coordinates as those of the display segment regions PA other than the display segment region PA including the high luminance portion LP 1  have the minimum transmittance (BL_min), the output luminance in these display segment regions PA can be reduced to restrain the black floating U. 
     In contrast, since the display segment region PA including the high luminance portion LP 1  needs light from the light source, the transmittance of a dimming area LDB at the same coordinates as those of this display segment region PA is set to transmittance (such as the maximum transmittance (BL_max)) higher than the minimum transmittance (BL_min). As a result, as illustrated in  FIG. 37 , the black floating U is not restrained in the display segment region PA including the high luminance portion LP 1 . Accordingly, the abrupt change lines ST 2 , ST 3 , ST 4 , and ST 5  of the output luminance are generated at the boundaries between the display segment region PA including the high luminance portion LP 1  and the display segment regions PA adjacent to the display segment region PA. 
     Accordingly, the signal processor  10  of the second embodiment serves as a controller that increases, when adjacent two of the dimming areas LDB differ in light transmittance from each other, the output gradation values of pixels located in one of the dimming areas LDB having lower light transmittance in the vicinity of the boundary (such as in an area containing the predetermined number of pixels (x_pix) extending from the boundary) between the two adjacent dimming areas LDB. This control can restrain the generation of the abrupt change lines ST 2 , ST 3 , ST 4 , and ST 5  of the output luminance. 
       FIG. 38  is a flowchart of processing by the signal processor  10  of the second embodiment. The signal processor  10  performs the acquisition of the required luminance information (Step S 21 ), the calculation of the transmittance of the dimming areas LDB (Step S 22 ), the generation of the image correction coefficient (Step S 23 ), the calculation of the lighting amounts (Step S 24 ), the generation of the inverse of the luminance (Step S 25 ), and the calculation of the output gradation values (Step S 26 ). Of the processes from Step S 21  to Step S 26 , the processes from Step S 22  to Step S 23  and the processes from Step S 24  to Step S 25  may be performed in parallel after the process at Step S 21 . The process at Step S 26  is performed after the processes at Step S 23  and Step S 25 . 
       FIG. 39  is a diagram schematically illustrating an example of processing details of Step S 21  to Step S 25  in the flowchart illustrated in  FIG. 38 . The following description illustrates a case where the display device of the second embodiment includes the light source device  50 B. If the display device of the second embodiment includes the light source device  50 A, the following description should be read by replacing the light sources  51 B with the light source  51 A. During the acquisition of the required luminance information (Step S 21 ), the required luminance information acquirer  101  acquires the luminance of the light source  51 B required for each of the display segment regions PA.  FIG. 39  illustrates a case where, at Step S 21 , the required luminance levels of the display segment regions PA at (x 3 ,y 1 ) and (x 3 ,y 3 ) are 100[%] and 20 [%], respectively, and the required luminance levels of the display segment regions PA of the other positions are 0[%]. 
     During the calculation of the transmittance of the dimming areas (Step S 22 ), the dimming gradation calculator  102 A calculates the transmittance of the dimming areas LDB and the gradation values corresponding to the transmittance.  FIG. 39  illustrates a case where, at Step S 22 , the transmittance levels of the dimming areas LDB at (x 3 ,y 1 ) and (x 3 ,y 3 ) are the maximum transmittance (BL_max) (expressed as 100[%] in  FIG. 39 ), and the transmittance levels of the dimming areas LDB at the other coordinates are the minimum transmittance (BL_min) (expressed as 0[%] in  FIG. 39 ). 
     During the generation of the image correction coefficient (Step S 23 ), the image correction coefficient generator  103 A calculates the image correction coefficient (kpix (v)).  FIG. 39  illustrates an example in which, at Step S 23 , the target pixels are set in the display segment regions PA at (x 3 ,y 2 ) and (x 3 ,y 4 ), and the correction values for increasing the gradation values are calculated for the case where the gradation values of the target pixels are (R,G,B)=(0,0,0). More specifically, assuming that, among the pixels  48  included in the display segment region PA at (x 3 ,y 2 ), a pixel  48  located in a position closest to the boundary between the display segment region PA at (x 3 ,y 1 ) and the display segment region PA at (x 3 ,y 2 ) serves as one end, the pixels  48  located within the area containing the predetermined number of pixels (x_pix) extending from the one end side toward the other end side are selected as the target pixels. In addition, assuming that, among the pixels  48  included in the display segment region PA at (x 3 ,y 2 ), a pixel  48  located in a position closest to the boundary between the display segment region PA at (x 3 ,y 2 ) and the display segment regions PA at (x 3 ,y 3 ) serves as the other end, pixels  48  located within the area containing the predetermined number of pixels (x_pix) extending from the other end side toward the one end side are selected as the target pixels. In this manner, the predetermined number of pixels (x_pix) may be determined in consideration of the case where the pixels  48  located within the areas containing the predetermined number of pixels (x_pix) extending from the one end side and the other end side in one of the display segment regions PA, are selected as the target pixels. For example, the predetermined number of pixels (x_pix) may be equal to or smaller than half the number of pixels in the Y-direction included in one of the display segment regions PA. In  FIG. 39 , assuming that, among the pixels  48  included in the display segment regions PA at (x 3 ,y 4 ), a pixel  48  located in a position closest to the boundary between the display segment region PA at (x 3 ,y 3 ) and the display segment region PA at (x 3 ,y 4 ) serves as one end, the pixels  48  located within the area containing the predetermined number of pixels (x_pix) extending from the one end side toward the other end side are selected as the target pixels. 
     While the example illustrated in  FIG. 39  illustrates the image correction coefficient (kpix (v)) in the Y-direction at (x 3 ), the image correction coefficient generator  103 A of the second embodiment also calculates the image correction coefficient (kpix (v)) in the Y-direction at coordinates other than (x 3 ) using the same scheme. However, in the example illustrated in  FIG. 39 , the required luminance of the display segment regions PA is 0[%] at coordinates in the X-direction other than (x 3 ). As a result, the correction value corresponding to the ratio (k) between the first contrast and the second contrast is not set by the image correction coefficient (kpix (v)) in the Y-direction at coordinates other than (x 3 ). 
     The image correction coefficient generator  103 A of the second embodiment also calculates the image correction coefficient (kpix (h)) in the X-direction using the same scheme. Specifically, to calculate the image correction coefficient (kpix (h)) at (y 1 ), the image correction coefficient generator  103 A sets the target pixels in the display segment regions PA at (x 2 ,y 1 ) and (x 4 ,y 1 ), and calculates the correction values for increasing the gradation values in the case where the gradation values of the target pixels are (R,G,B)=(0,0,0). To calculate the image correction coefficient (kpix (h)) at (y 3 ), the image correction coefficient generator  103 A sets the target pixels in the display segment regions PA at (x 2 ,y 3 ) and (x 4 ,y 3 ), and calculates the correction values for increasing the gradation values in the case where the gradation values of the target pixels are (R,G,B)=(0,0,0). The correction value corresponding to the ratio (k) between the first contrast and the second contrast is not set by the image correction coefficient (kpix (h)) in the X-direction at the other coordinates. 
     During the calculation of the lighting amounts (Step S 24 ), the lighting amount calculator  104  calculates the lighting amounts of the respective light sources  51 B.  FIG. 39  illustrates a case where, at Step S 24 , the lighting amounts are calculated such that the light sources  51 B at (x 3 ,y 1 ) and (x 3 ,y 3 ) are lit up at lighting amounts capable of obtaining the maximum luminance of 120 [%] and 30[%], respectively, in the display segment regions PA at (x 3 ,y 1 ) and (x 3 ,y 3 ). The lighting amount capable of obtaining the maximum luminance of 120[%] enables the display output in which luminance P 6  and P 7  in positions where the light from the light source  51 B is weakest in the display segment region PA at (x 3 ,y 1 ) are caused to be luminance of 100[%]. The lighting amount capable of obtaining the maximum luminance of 30[%] enables the display output in which luminance P 8  in a position where the light from the light source  51 B is weakest in the display segment region PA at (x 3 ,y 3 ) is caused to be luminance of 20[%]. 
     During the generation of the inverse of the luminance (Step S 25 ), the luminance distribution generator  105  generates the information indicating the luminance distribution obtained by the lighting amounts of the light sources  51 B calculated by the lighting amount calculator  104 . Then, the inverse luminance generator  106  generates the inverse luminance gainpix(h,v) corresponding to the position of the pixel  48  at (h,v) based on the luminance distribution generated by the luminance distribution generator  105 .  FIG. 39  illustrates the luminance distribution and the inverse luminance gainpix(h,v) in the Y-direction that are generated at Step S 25  corresponding to the light sources  51 B at (x 3 ). 
       FIG. 40  is a flowchart of the calculation processing of the output gradation values in  FIG. 38 . During the calculation of the output gradation values (Step S 26 ), the image processor  107 A calculates the output gradation values of the pixels  48  serving as the output image signals OP. Specifically, the image processor  107 A determines whether the gradation values of one of the pixels  48  included in the input signals IP are (R,G,B)=(0,0,0) (Step S 61 ). More specifically, as illustrated, for example, in Step S 61 , the image processor  107 A checks whether the gradation value is zero for each of the sub-pixels  49  included in the one of the pixels  48 . In other words, the image processor  107 A individually checks whether the gradation value (Rin(h,v)) of the first sub-pixel  49 R, the gradation value (Gin(h,v)) of the second sub-pixel  49 G, and the gradation value (Bin(h,v)) of the third sub-pixel  49 B included in the input signals IP are zero. 
     If the gradation values of one of the target pixels included in the input signals IP are (R,G,B)=(0,0,0), (Yes at Steps S 61 ), the image processor  107 A calculates the gradation value of each of the sub-pixels  49  included in one of the pixels  48  determined to be the target pixels, using Expressions (5), (6), and (7) given below (Step S 64 ). In the processing at Step S 64 , if Tx(h,y)×Ty(x,v)=1 (100%), this expression is replaced with Tx(h,y)×Ty(x,v)=0. In other words, if Tx(h,y)×Ty(x,v)=1 (100%), then Rout(h,v)=Gout(h,v)=Bout(h,v)=0. Tx(h,y) is a preprocessing coefficient in each position (h) of the pixels  48  arranged in the X-direction at a Y-coordinate (y). Ty(x,v) is a preprocessing coefficient in each position (v) of the pixels  48  arranged in the Y-direction at an X-coordinate (x).
 
 R out( h,v )= k×Tx ( h,y )× Ty ( x,v )  (5)
 
 G out( h,v )= k×Tx ( h,y )× Ty ( x,v )  (6)
 
 B out( h,v )= k×Tx ( h,y )× Ty ( x,v )  (7)
 
       FIG. 41  is a diagram illustrating examples of the preprocessing coefficients Tx(h,y) and Ty(x,v) used for calculating the gradation values of the target pixels in the second embodiment. The image processor  107 A uses the ratio (k) between the first contrast and the second contrast and the preprocessing coefficients Tx(h,y) and Ty(x,v) to calculate the gradation value of each of the sub-pixels  49  included in one of the pixels  48  determined to be the target pixels. Specifically, cases are distinguished based on whether a condition is satisfied that the light transmittance of one of the two adjacent dimming areas LDB is the maximum transmittance (BL_max) and that of the other of the two adjacent dimming areas LDB is the minimum transmittance (BL_min) at Step S 22 . If the condition is satisfied, the preprocessing coefficients Tx(h,y) and Ty(x,v) are set to be smaller than 1 (100%) within the area containing the predetermined number of pixels (x_pix) extending from the boundary between the two dimming areas LDB. Specifically, assuming that the dimming area LDB having the maximum transmittance (BL_max) serves as one end side and the dimming area LDB having the minimum transmittance (BL_min) serves as the other end side, the preprocessing coefficients Tx(h,y) and Ty(x,v) are set so as to gradually decrease from the one end side toward the other end side within the area containing the predetermined number of pixels (x_pix). The preprocessing coefficients Tx(h,y) and Ty(x,v) are set to 1 (100%) in the two dimming areas LDB not satisfying the condition. The above-described setting may be performed by the image processor  107 A, by the image correction coefficient generator  103 , or by another component included in the signal processor  10 . 
     To simplify the explanation,  FIG. 41  illustrates the preprocessing coefficients Tx(h,y) and Ty(x,v) based on an example of the transmittance values of 16 dimming areas LDB defined by a combination of coordinates x 6 , x 7 , x 8 , and x 9  with coordinates y 1 , y 2 , y 3 , and y 4 . In  FIG. 41 , the dimming areas LDB at (x 8 ,y 2 ) and (x 9 ,y 3 ) have the maximum transmittance (BL_max), and the other dimming areas LDB have the minimum transmittance (BL_min). Accordingly, in  FIG. 41 , for example, a preprocessing coefficient Tx(h, 2 ) at the horizontal pixel coordinate (h) at (y 2 ) includes values smaller than 1 (100%) within the area containing the predetermined number of pixels (x_pix) on the (x 8 ,y 2 ) sides of (x 7 ,y 2 ) and (x 9 ,y 2 ). A preprocessing coefficient Tx(h, 3 ) at the horizontal pixel coordinate (h) at (y 3 ) includes values smaller than 1 (100%) within the area containing the predetermined number of pixels (x_pix) on the (x 9 ,y 3 ) side of (x 8 ,y 3 ). A preprocessing coefficient Ty(8,v) at the vertical pixel coordinate (v) at (x 8 ) includes values smaller than 1 (100%) within the area containing a predetermined number of pixels (y_pix) on the (x 8 ,y 2 ) sides of (x 8 ,y 1 ) and (x 8 ,y 3 ). A preprocessing coefficient Ty(9,v) at the vertical pixel coordinate (v) at (x 9 ) includes values smaller than 1 (100%) within the area containing the predetermined number of pixels (y_pix) on the (x 9 ,y 3 ) sides of (x 9 ,y 2 ) and (x 9 ,y 4 ). These preprocessing coefficients Tx(h, 2 ), Tx(h, 3 ), Ty(8,v), and Ty(9,v) are set to 1 (100%) except in the areas containing the predetermined number of pixels (y_pix) and areas containing the predetermined number of pixels (x_pix) specially mentioned above. Preprocessing coefficients Tx(h, 1 ) and Tx(h, 4 ) at the horizontal pixel coordinate (h) at (y 1 ) and (y 4 ) are set to 1 (100%) regardless of the coordinate (h) in the X-direction of the pixel  48 . Preprocessing coefficients Ty(6,v) and Ty(7,v) at the vertical pixel coordinate (v) at (x 6 ) and (x 7 ) are set to 1 (100%) regardless of the coordinate (v) in the Y-direction of the pixel  48 . 
     As an example, if x_pix=5, that is, the area containing the predetermined number of pixels (x_pix) has a width of five pixels, the values smaller than 1 (100%) can be set as 0.99 (99%), 0.75 (75%), 0.50 (50%), 0.25 (25%), and 0.01 (1%) from the one end side toward the other end side within the area containing the predetermined number of pixels (x_pix). These are, however, mere examples, and the values are not limited thereto. The specific value of x_pix and the specific values smaller than 1 (100%) can be changed as appropriate. The change in value from the one end side toward the other end side may be along a linear line or along a curve. The value of y_pix may be the same as or different from that of x_pix. 
     As described above, in the areas of the predetermined number of pixels (x_pix) and areas containing the predetermined number of pixels (y_pix) where the pixels  48  serving as the target pixels are located, at least one of the preprocessing coefficients Tx(h,y) and Ty(x,v) is set to values smaller than 1 (100%). Therefore, the image processor  107 A can increase the gradation values of the target pixels by calculating the gradation values, using Expressions (5), (6), and (7) given above. Consequently, the luminance difference caused by the difference in transmittance between the two adjacent dimming areas LDB can be made less visible. Accordingly, the occurrence of the belt-like halo can be restrained, and the improvement can be made in display quality and contrast perception resulting from the restraint of the black floating U. 
     If any one of the display segment regions PA has the same coordinates as one of the dimming areas LDB having the minimum transmittance (BL_min) and adjacent in both the X-direction and the Y-direction to other of the dimming areas LDB having the maximum transmittance (BL_max), the one of the display segment regions PA is considered to be affected by light from both the X-direction and the Y-direction. As a result, for the target pixels under such a condition, both the preprocessing coefficient Tx(h,y) and the preprocessing coefficient Ty(x,v) are smaller than 1 (100%). For example, both the preprocessing coefficient Tx(h,y) and the preprocessing coefficient Ty(x,v) are smaller than 1 (100%) at XY-coordinates SP(h,v) represented by a combination of an X-coordinate SP (h) of one of the pixels  48  among those having the preprocessing coefficient Tx(h, 2 ) and a Y-coordinate SP (v) of one of the pixels  48  among those having the preprocessing coefficient Ty(9,v) illustrated in  FIG. 41 . If the preprocessing coefficient Tx(h,y) at the X-coordinate SP (h) and the preprocessing coefficient Ty(9,v) at the Y-coordinate SP (v) are 0.8 (80%), then Tx(h,y)×Ty(x,v)=0.8×0.8=0.64. Assuming that one of two dimming areas LDB adjacent to each other in either one of the X-direction and the Y-direction has the maximum transmittance (BL_max) and the other has the minimum transmittance (BL_min), the above-given multiplication between the preprocessing coefficients Tx(h,y) and Ty(x,v) having values smaller than 1 (100%) is not applied to any one of the display segment regions PA having the same coordinates as the other dimming area LDB having the minimum transmittance (BL_min). Consequently, the preprocessing coefficient Tx(h,y) or the preprocessing coefficient Ty(x,v) of the other dimming area LDB not having the maximum transmittance (BL_max) is set to 1 (100%). Accordingly, a value smaller than 1 (100%) set as the preprocessing coefficient Tx(h,y) or the preprocessing coefficient Ty(x,v) of the one of the dimming areas LDB is reflected. 
     When both the preprocessing coefficients Tx(h,y) and Ty(x,v) are 1 (100%), the correction value corresponding to the ratio (k) between the first contrast and the second contrast is reflected in the pixels other than the target pixels if the gradation values are calculated without providing exceptions in Expressions (5), (6), and (7). Accordingly, if Tx(h,y)×Ty(x,v)=1 (100%), this result is replaced with Tx(h,y)×Ty(x,v)=0, whereby the pixels  48  reflecting the correction value corresponding to the ratio (k) between the first contrast and the second contrast can be limited to the target pixels. 
     If the gradation values of one of the pixels  48  included in the input signals IP are not (R,G,B)=(0,0,0) (No at Step S 61 ), the image processor  107 A multiplies the gradation value of each of the sub-pixels  49  included in the one of the pixels  48  by the inverse luminance gainpix(h,v) (Step S 63 ), in the same manner as in the first embodiment. The configuration of the display device of the second embodiment is the same as that of the display device  1  of the first embodiment except in the particulars described above. 
     As described above, the second embodiment can restrain the occurrence of the belt-like halo with respect to both the two intersecting directions (such as the X-direction and the Y-direction). 
     The display device  1  and the like according to the above-described embodiments and the modification (embodiments and the like) are employed in, for example, head-up displays. This is, however, merely a specific example of the display device  1  and the like, and the present invention is not limited thereto. The display device  1  and the like can be appropriately employed to other applications, products, and the like. 
     The above-described embodiments and the like exemplify the case where the dimming panel (such as the dimming panel  80  or  80 B) is located between the image display panel  30  and the light source device (such as the light source device  50 ,  50 A, or  50 B). This is, however, a mere example of the positional interrelation among the image display panel  30 , the dimming pane, and the light source device, and the present invention is not limited thereto. For example, the dimming panel may be located on the display surface side of the image display panel  30 . The dimming panel only needs to be provided on the display panel side of the light source device. 
     In the above-described embodiments and the like, the signal processor  10  serving as the controller determines the lighting amounts of the light sources  51 ,  51 A, or  51 B. This is, however, a mere example, and the specific details of the control are not limited thereto. The lighting amounts of the light sources  51 ,  51 A, or  51 B may be set in advance. 
     The concept on the correspondence relation between the transmittance and the correction values for the target pixels, such as the expressions given in the description of the one-dimensional dimming areas illustrated in the first embodiment, can be applied to the case where the transmittance of the dimming areas arranged in the one-dimensional direction (such as the X-direction) is uniform in the second embodiment. This is because, in the second embodiment, the state that the transmittance of the dimming areas arranged in the one-dimensional direction (such as the X-direction) is uniform indicates that the dimming areas are in a one-dimensionally adjusted state. 
     Other operational effects accruing from the aspects described in the embodiments and the like that are obvious from the description herein, or that are appropriately conceivable by those skilled in the art will naturally be understood as accruing from the present invention.