JP2017203981A - Display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display device that can achieve local dimming allowing a smaller burden to make a boundary hard to be visible.SOLUTION: A display device comprises: a plurality of light sources that are lined along at least one direction; a display unit that is illuminated with light from the plurality of light sources to output an image; a light source control unit that controls an operation of the light source on the basis of a display output content of the display unit; and a display control unit that controls an output gradation value of a part of a plurality of pixels or all thereof on the basis of an amount of light emission of the light source. A display area is segmented into a plurality of partial areas associated with each of the plurality of light sources. The light source control unit is configured to determine the amount of light emission of one light source associated with one partial area in accordance with luminance of light necessary in the one partial area, and the display control unit is configured to, when an amount of light emission of two light sources associated with adjacent two partial areas is different, correct an output gradation value of the pixels until m-th pixel from a boundary between the partial areas.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a display device.

  A display device having a local dimming function that divides a light source device such as a backlight into a plurality of regions and controls light emission of the light source for each region in accordance with a video signal of the divided regions is known (for example, Patent Document 1).

JP 2013-246426 A

  There are individual differences in each of the plurality of light sources, and the luminance distribution of light from each differs. For this reason, for strict local dimming, it is necessary to hold information indicating the luminance distribution of each of the plurality of light sources, and a resource for holding such information is required. Since the scale of such resources increases in proportion to the number of light sources, it becomes a heavy burden when realizing local dimming. Further, the light from each of the plurality of light sources is not irradiated only to the corresponding region strictly, but is brought to the vicinity of the corresponding region such as the adjacent region. For this reason, in order to perform strict local dimming, it is necessary to perform an operation in consideration of the relationship between the plurality of light sources, and resources for the operation are required. Since the scale of such resources increases with the number of areas, it becomes a heavy burden when realizing local dimming.

  In addition, simply performing local dimming may cause a boundary between regions to be visually recognized due to a luminance difference between adjacent regions.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a display device capable of realizing local dimming with less burden and less visibility of the boundary.

A display device according to one embodiment of the present invention includes a display region including a plurality of light sources arranged in at least one direction and n ₁ pixels, and is illuminated with light from the plurality of light sources to display an image. A display unit for output, a light source control unit for controlling the operation of the light source based on display output content of the display unit, and an output gradation of some or all of the plurality of pixels based on the light emission amount of the light source A display control unit that controls a value, wherein the display area is divided into a plurality of partial areas associated with each of the plurality of light sources, and one of the partial areas is at least along the one direction. has n ₂ pixels arranged, the light source control unit determines the light emission amount of one light source associated with the one partial region in response to light intensity required for one partial region, wherein Display control unit supports two adjacent partial areas In the case where the emitted light amounts of the two light sources are different, the light emission amount is relatively small among the pixels of the first partial region which is one partial region associated with the first light source with the relatively large light emission amount. Performing the first correction to lower the output gradation value of the pixels in the first range from the boundary with the second partial region, which is the other partial region associated with the two light sources, to the position of the mth pixel, The second correction for increasing the output gradation value of the pixels in the second range from the boundary to the position of the mth pixel among the pixels of the second partial region is performed, and the output gradation value after the first correction Means that the pixel controlled by the output gradation value before the first correction is less than the light emission amount of the first light source having a relatively large light emission amount, and the light emission is intermediate between the light emission amounts of the two light sources. This is the output gradation value when illuminated by light from the first virtual light source that exceeds the amount, The output gradation value after the second correction is such that the pixel controlled by the output gradation value before the second correction exceeds the light emission amount of the second light source with a relatively small light emission amount, and the two It is an output gradation value when illuminated by light from the second virtual light source that is lower than the intermediate light emission amount of each light source, and n ₁ > n ₂ > m ≧ 1.

FIG. 1 is a schematic diagram showing a main configuration of a display device according to an embodiment of the present invention. FIG. 2 is a block diagram illustrating a system configuration example of the display unit according to the present embodiment. FIG. 3 is a circuit diagram showing a drive circuit for driving the pixels of the display unit according to the present embodiment. FIG. 4 is a diagram illustrating an example of display area division. FIG. 5 is a diagram illustrating an example of a correspondence relationship between a plurality of light sources included in the light source unit and a plurality of partial regions. FIG. 6 is a graph showing an example of a correspondence relationship between the control patterns of the four light sources arranged along one direction, the luminance distributions of the four light sources, and the luminance distribution obtained by combining the light from the four light sources. is there. FIG. 7 is a graph showing the calculated luminance distribution of the four partial areas obtained by correcting the output gradation value according to the present embodiment. FIG. 8 shows the calculated luminance distribution between two partial areas, the position of the pixel from the boundary between the partial areas to the mth pixel, and the position of the ath pixel from the farthest from the boundary among the pixels from the boundary to the mth pixel. It is a graph which shows an example of the relationship. FIG. 9 is a schematic diagram illustrating an example of correction of output gradation values in the X direction and the Y direction. FIG. 10 shows the calculated luminance distribution between two partial areas, the position of the pixel from the boundary between the partial areas to the mth pixel, and the position of the ath pixel from the farthest from the boundary among the pixels from the boundary to the mth pixel. It is a graph which shows an example of the relationship.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that the disclosure is merely an example, and those skilled in the art can easily conceive of appropriate modifications while maintaining the gist of the invention are naturally included in the scope of the present invention. In addition, the drawings may be schematically represented with respect to the width, thickness, shape, and the like of each part in comparison with actual aspects for the sake of clarity of explanation, but are merely examples, and the interpretation of the present invention is not limited. It is not limited. In addition, in the present specification and each drawing, elements similar to those described above with reference to the previous drawings are denoted by the same reference numerals, and detailed description may be omitted as appropriate.

  FIG. 1 is a schematic diagram illustrating a main configuration of a display device 1 according to an embodiment of the present invention. The display device 1 includes, for example, a light source unit 6 that functions as a light source device, a display unit 2 that is illuminated with light L from the light source unit 6 and outputs an image. The light L emitted from the light source unit 6 is reflected by the display unit 2, the mirror M, and the windshield FG and reaches the user H, so that the light L is recognized as an image VI in the field of view of the user H. That is, the display device 1 of the present embodiment functions as a head-up display (HUD) using the mirror M and the windshield FG.

  Next, the display unit 2 will be described. The display unit 2 of the present embodiment is a transmissive liquid crystal display that transmits light L and outputs an image, but is a reflective liquid crystal display or a digital micromirror device (DMD (registered trademark)). Or the like.

  FIG. 2 is a block diagram illustrating a system configuration example of the display unit 2 according to the present embodiment. FIG. 3 is a circuit diagram illustrating a drive circuit that drives the pixels Pix of the display unit 2 according to the present embodiment. The pixel Pix includes a plurality of subpixels Vpix. The display unit 2 is, for example, a transmissive liquid crystal display, and includes an image output panel and a driving element 3, for example, a DDIC (Display Driver Integrated Circuit).

  The image output panel is, for example, a translucent insulating substrate such as a glass substrate and a display on a surface of the glass substrate in which a large number of pixels Pix (see FIG. 3) including liquid crystal cells are arranged in a matrix (matrix). It has area 21. The glass substrate includes a first substrate on which a large number of pixel circuits including active elements (for example, transistors) are arranged and formed in a matrix, and a second substrate that is arranged to face the first substrate with a predetermined gap. And a substrate. The gap between the first substrate and the second substrate is held at a predetermined gap by photo spacers arranged and formed at various locations on the first substrate. Then, liquid crystal is sealed between the first substrate and the second substrate. In addition, arrangement | positioning and a magnitude | size of each part shown in FIG. 2 are typical, and do not reflect actual arrangement | positioning.

The display area 21 has a matrix (matrix) structure in which subpixels Vpix including a liquid crystal layer are arranged in M rows × N columns. In this specification, a row refers to a pixel row having N subpixels Vpix arranged in one direction. A column refers to a pixel column having M subpixels Vpix arranged in a direction orthogonal to the direction in which the rows are arranged. The values of M and N are determined according to the vertical resolution and the horizontal resolution. In the display area 21, scanning lines 24 ₁ , 24 ₂ , 24 ₃ ,..., 24 _M are wired for each row with respect to the arrangement of M rows and N columns of subpixels Vpix, and signal lines 25 ₁ , 25 for each column. ₂ , 25 ₃ ,..., 25 _N are wired. Hereinafter, in the present embodiment, the scanning lines 24 ₁ , 24 ₂ , 24 ₃ ,..., 24 _M are represented as scanning lines 24, and the signal lines 25 ₁ , 25 ₂ , 25 ₃ ,. _N may be represented as a signal line 25. In the present embodiment, any three scanning lines 24 ₁ , 24 ₂ , 24 ₃ ,..., 24 _M are replaced by scanning lines 24 _m , 24 _{m + 1} , 24 _{m + 2} (where m is m ≦ M-2, a natural number), and any four signal lines 25 ₁ , 25 ₂ , 25 ₃ ,..., 25 _N are represented by signal lines 25 _n , 25 _{n + 1} , 25 _{n + 2} , 25 _{n + 3} (where n is a natural number satisfying n ≦ N−3).

  The drive element 3 is a circuit mounted on the glass substrate of the image output panel by, for example, COG (Chip On Glass). The drive element 3 is connected to the control unit 100 via a flexible printed circuit (FPC) (not shown). The control unit 100 is a circuit that controls the operation of the display unit 2 and the light source unit 6. Specifically, the control unit 100 functions as, for example, the display control unit 101 and the light source control unit 102. The display control unit 101 outputs pixel signals for individually driving a plurality of sub-pixels Vpix constituting the pixel Pix. The pixel signal is, for example, a signal obtained by combining individual gradation values of red (R), green (G), blue (B), and white (W), which will be described later. The type of color and the number of colors to be associated are arbitrary. Further, the display control unit 101 has a function of controlling some or all output gradation values of the plurality of pixels Pix based on the light emission amount of the light source 6 a controlled by the light source control unit 102. The light source control unit 102 controls the operation of the light source 6 a based on the display output content of the display unit 2. Specifically, the light source control unit 102 individually controls the operations of the plurality of light sources 6 a constituting the light source unit 6. Further, the control unit 100 may have a function of outputting various signals (for example, a master clock, a horizontal synchronization signal, a vertical synchronization signal, etc.) used in connection with the operation of the display unit 2. A configuration for outputting such various signals may be provided separately.

  In the present embodiment, the light source control unit 102 employs so-called one-frame delay control that controls the operation of the plurality of light sources 6a based on the pixel signal output from the display control unit 101 one frame before. With such one-frame delay control, it is possible to omit a buffer for holding pixel signals that is required when controlling the operation of the plurality of light sources 6a in the same frame as the pixel signals. Note that a buffer may be provided to control the operations of the plurality of light sources 6a in the same frame as the pixel signal.

  The display unit 2 is connected to an external input power source or the like (not shown). The external input power supply supplies power necessary for the operation of the display unit 2 via a connection terminal 41 and the like which will be described later.

  More specifically, the driving element 3 operates the display unit 2 according to various signals given from the control unit 100, for example. The control unit 100 outputs, for example, a master clock, a horizontal synchronization signal, a vertical synchronization signal, a pixel signal, a drive command signal for the light source unit 6, and the like to the drive element 3. The drive element 3 functions as a gate driver and a source driver based on these signals and the like. Note that one or both of the gate driver and the source driver may be formed on the substrate using a thin film transistor (TFT) described later. In that case, one or both of the gate driver and the source driver may be electrically connected to the driving element 3. Further, the source driver and the gate driver may be electrically connected to different drive elements 3, or may be connected to the same drive element 3.

The gate driver latches digital data in units of one horizontal period corresponding to the horizontal synchronization signal in synchronization with the vertical synchronization signal and the horizontal synchronization signal. The gate driver sequentially outputs the latched digital data for one line as a vertical scanning pulse, and supplies it to the scanning lines 24 (scanning lines 24 ₁ , 24 ₂ , 24 ₃ ,..., 24 _M ) of the display area 21. Sub-pixels Vpix are sequentially selected in units of rows. For example, the gate driver outputs digital data in order from the one end side to the other end side of the display area 21 of the scanning lines 24 ₁ , 24 ₂ ,. Further, the gate driver can also output digital data in order from the other end side to the one end side of the display area 21 of the scanning lines 24 _M ,.

For example, pixel drive data generated based on the pixel signal is given to the source driver. The source driver applies the signal line 25 (signal lines 25 ₁ , 25) to the subpixel Vpix in the row selected by the vertical scanning by the gate driver, for each subpixel, for each subpixel, or for all subpixels at once. ₂ , 25 ₃ ,..., 25 _N ), the pixel driving data is written.

  As driving methods for liquid crystal displays, driving methods such as line inversion, dot inversion, and frame inversion are known. Line inversion is a driving method in which the polarity of a video signal is inverted at a time period of 1H (H is a horizontal period) corresponding to one line (one pixel row). The dot inversion is a driving method in which the polarity of the video signal is alternately inverted for each subpixel adjacent to each other in two intersecting directions (for example, the matrix direction). Frame inversion is a driving method in which video signals written to all subpixels Vpix are inverted at the same polarity at a time for each frame corresponding to one screen. The display unit 2 can employ any of the above-described driving methods.

In the description according to the present embodiment, when each of the M scanning lines 24 ₁ , 24 ₂ , 24 ₃ ,..., 24 _M is comprehensively handled, it may be described as the scanning line 24. Scan lines _{24 m, 24} m + 1, _{24 m + 2} in Figure 3, the scanning lines ₂₄ 1 of the _M, 24 _2, 24 3, ..., which is part of the 24 _M. In addition, when each of the N signal lines 25 ₁ , 25 ₂ , 25 ₃ ,..., 25 _N is handled comprehensively, it may be described as a signal line 25. Signal lines 25 _n , 25 _{n + 1} , 25 _{n + 2} in FIG. 3 are part of N signal lines 25 ₁ , 25 ₂ , 25 ₃ ,..., 25 _N.

  In the display area 21, wirings such as a signal line 25 for supplying a pixel signal to the TFT element Tr of the sub-pixel Vpix and a scanning line 24 for driving each TFT element Tr are formed. As described above, the signal line 25 extends in a plane parallel to the surface of the glass substrate described above, and supplies pixel driving data generated based on the pixel signal for outputting an image to the sub-pixel Vpix. . The subpixel Vpix includes a TFT element Tr and a liquid crystal element LC. The TFT element Tr is composed of a thin film transistor. In this example, the TFT element Tr is composed of an n-channel MOS (Metal Oxide Semiconductor) TFT. One of the source or drain of the TFT element Tr is connected to the signal line 25, the gate is connected to the scanning line 24, and the other of the source or drain is connected to one end of the liquid crystal element LC. The liquid crystal element LC has one end connected to the other of the source or drain of the TFT element Tr and the other end connected to the common electrode COM. A drive signal is applied to the common electrode COM by a drive electrode driver (not shown). The drive electrode driver may be one configuration of the drive element 3 or an independent circuit.

  The sub-pixel Vpix is connected to another sub-pixel Vpix belonging to the same row of the display area 21 by the scanning line 24. The scanning line 24 is connected to a gate driver, and a vertical scanning pulse of a scanning signal is supplied from the gate driver. The sub-pixel Vpix is connected to another sub-pixel Vpix belonging to the same column of the display area 21 by the signal line 25. The signal line 25 is connected to a source driver, and a pixel signal is supplied from the source driver. Further, the sub-pixel Vpix is connected to another sub-pixel Vpix belonging to the same column of the display area 21 by the common electrode COM. The common electrode COM is connected to a drive electrode driver (not shown), and a drive signal is supplied from the drive electrode driver.

  The gate driver applies a vertical scanning pulse to the gate of the TFT element Tr of the sub-pixel Vpix via the scanning line 24, so that one row of the sub-pixels Vpix formed in a matrix in the display area 21 ( One horizontal line) is sequentially selected as an image output target. The source driver supplies the pixel signal to the sub-pixel Vpix included in one horizontal line sequentially selected by the gate driver via the signal line 25. In these subpixels Vpix, image output of one horizontal line is performed in accordance with the supplied pixel signal.

  As described above, the display unit 2 sequentially selects one horizontal line by driving the gate driver to sequentially scan the scanning lines 24. The display unit 2 outputs an image for each horizontal line when the source driver supplies a pixel signal via the signal line 25 to the sub-pixel Vpix belonging to one horizontal line. When performing this image output operation, the drive electrode driver applies a drive signal to the common electrode COM corresponding to the one horizontal line.

  The display area 21 has a color filter. The color filter includes a lattice-shaped black matrix 76a and an opening 76b. As shown in FIG. 3, the black matrix 76a is formed so as to cover the outer periphery of the sub-pixel Vpix. That is, the black matrix 76a has a lattice shape by being arranged at the boundary between the two-dimensionally arranged subpixel Vpix and the subpixel Vpix. The black matrix 76a is formed of a material having a high light absorption rate. The opening 76b is an opening formed in the lattice shape of the black matrix 76a, and is arranged corresponding to the sub-pixel Vpix.

  The opening 76b includes a color region corresponding to three colors (for example, red (R), green (G), and blue (B)), or four colors of sub-pixels Vpix. Specifically, the opening 76b is colored in, for example, three colors of red (R), green (G), and blue (B) that are one form of the first color, the second color, and the third color. And a color region of a fourth color (for example, white (W)). The color filter periodically arranges, for example, color regions colored in three colors of red (R), green (G), and blue (B) in the opening 76b. When the fourth color is white (W), the white (W) opening 76b is not colored by the color filter. When the fourth color is another color, the color adopted as the fourth color is colored by the color filter. In the present embodiment, each subpixel Vpix shown in FIG. 3 corresponds to the pixel Pix as a set of a total of four colors of three color regions of R, G, and B and a fourth color (for example, white (W)). It is attached. The pixel signal for one pixel Pix in this embodiment is an output of one pixel Pix having sub-pixels Vpix of red (R), green (G), blue (B), and the fourth color (white (W)). Is a pixel signal corresponding to. In the description of this embodiment, red (R), green (G), blue (B), and white (W) may be simply referred to as R, G, B, and W. When the pixel Pix includes sub-pixels Vpix having two colors or less or five colors or more, digital data corresponding to the number of colors may be supplied based on the original data of the image.

  The color filter may be a combination of other colors as long as it is colored in a different color. Generally, in the color filter, the luminance of the green (G) color region is higher than the luminance of the red (R) color region and the blue (B) color region. Further, when the fourth color is white (W), the color filter may be white by using a light-transmitting resin.

  The display area 21 is arranged in an area where the scanning lines 24 and the signal lines 25 overlap with the black matrix 76a of the color filter when viewed from the direction orthogonal to the front. That is, the scanning line 24 and the signal line 25 are hidden behind the black matrix 76a when viewed from the direction orthogonal to the front. Further, in the display area 21, an area where the black matrix 76a is not disposed becomes an opening 76b.

FIG. 4 is a diagram illustrating an example of the division of the display area 21. The display area 21 is divided into a plurality of partial areas. Specifically, for example, as shown in FIG. 4, the display area 21 is divided into eight equal parts such as X ₁ , X ₂ ,..., X ₈ along the X direction, and Y ₁ , An 8 × 4 partial region is provided by dividing into four equal parts such as Y ₂ , Y ₃ , and Y ₄ . As an example, in the case of the display region 21 in which 800 pixels in the X direction and 480 pixels in the Y direction, that is, 800 × 480 pixels Pix are arranged in a matrix, one partial region shown in FIG. Have The number of pixels in the example shown in FIG. 4 and the display area 21 is merely an example, and is not limited to this, and can be changed as appropriate.

  FIG. 5 is a diagram illustrating an example of a correspondence relationship between a plurality of light sources 6 a included in the light source unit 6 and a plurality of partial regions. The arrangement of the light sources 6a shown in FIG. 5 is an arrangement corresponding to the partial area breaks shown in FIG. The plurality of partial areas are associated with each of the plurality of light sources 6 a included in the light source unit 6. Specifically, for example, as shown in FIG. 5, one light source 6a is arranged in each of the plurality of partial regions. The light source 6a is, for example, a light emitting diode (LED), but this is an example of a specific configuration of the light source 6a and is not limited thereto, and can be changed as appropriate. In FIG. 5, one light source 6a is arranged in each partial area. However, the light emission amount can be individually controlled in each partial area, and the luminance of each partial area can be adjusted. If it is, it will not be restricted to this but can be changed suitably.

  Note that the light from each of the plurality of light sources 6a is not radiated only to the corresponding partial area, but to the partial area near the corresponding partial area. For this reason, for example, when two light sources 6a corresponding to two adjacent partial areas are both lit, the two partial areas are irradiated with the combined light of the two light sources 6a. obtain.

In the present embodiment, the light source control unit 102 employs local dimming in connection with operation control of the plurality of light sources 6a. That is, the light source control unit 102 controls the operations of the plurality of light sources 6a so that the light emission amounts of the plurality of light sources 6a become the light emission amounts according to the luminance required for each of the plurality of partial regions. For example, the output gradation value of all the pixels Pix included in the partial area (X ₁ , Y ₁ ) shown in FIG. 4 is black (for example, (R, G, B) = (0, 0, 0)). In this case, the light source control unit 102 does not turn on the light source 6a corresponding to (X ₁ , Y ₁ ). Further, in the case where the ratio of the output gradation values of the pixels Pix that require the light with the highest luminance is 1: 2 in each of the two partial areas, the light source control unit 102 will be schematically described in a simplified manner. The luminance ratio by the light emission of the two light sources 6a corresponding to each of the two partial areas is controlled to be 1: 2.

  However, as described above, the light from each of the plurality of light sources 6a is not radiated only to the corresponding partial area, but to the partial area near the corresponding partial area. For this reason, if strict local dimming is to be performed, it is necessary to consider the relationship between the light sources 6a.

FIG. 6 shows the control pattern P of the four light sources 6a arranged along one direction, the luminance distributions T ₂ , T ₃ , T ₄ , T ₅ of each of the four light sources 6a, and the light from the four light sources 6a. is a graph showing an example of the correspondence between the synthesized luminance distribution T _1. The horizontal axis of FIG. 6 and FIG. 7 described later is either the X direction or the Y direction. In FIG. 6 and FIG. 7 to be described later, four light sources 6a corresponding to four partial regions n, (n + 1), (n + 2), and (n + 3) arranged along one direction (X direction or Y direction) are illustrated. Yes. The partial region (n + 3) is a partial region located at an end in one direction.

In the case of the example shown in FIG. 6, the four light sources 6a corresponding to the four partial regions n, (n + 1), (n + 2), and (n + 3) correspond to the luminance distribution T corresponding to the control pattern P of the four light sources 6a. ₂ , T ₃ , T ₄ , T ₅ are turned on with the light emission amount. Thus, four partial areas n, (n + 1), (n + 2), the luminance distribution of light emitted in (n + 3), so that the luminance distribution _{T 1} light is synthesized from four light sources 6a. More specifically, among the luminance distribution T _1, the luminance T _a of light at a predetermined position in the partial region (n + 2), luminance caused by light from each of the four light sources 6a at the predetermined position _{T b, T c, T d} , by synthesis _{T e.}

  Note that the control pattern P shown in FIG. 6 indicates the light emission amounts indicated by the drive signals for the four light sources 6a corresponding to the four partial areas n, (n + 1), (n + 2), and (n + 3), that is, the four partial areas n. , (N + 1), (n + 2), and (n + 3), the light emission amounts of the four light sources 6a determined corresponding to the luminances obtained from the respective luminances are shown. In FIG. 6, the required luminance increases in the order of partial areas (n + 1), n, (n + 3), and (n + 2).

Thus, since no luminance distribution T ₁ coincides with the control pattern P, strictly to be obtained a luminance distribution T _1, the luminance distribution _{T 2, T 3, T 4} , T 5 the operation needs based Become. However, it is difficult to generalize the luminance distribution of each of the plurality of light sources 6a such as the luminance distributions T ₂ , T ₃ , T ₄ , and T ₅ using an equation with coordinates as variables. In order to accurately obtain information indicating the luminance distribution of each light source 6a according to the light emission amount indicated by the drive signal, it is necessary to perform individual measurement in advance. In order to hold such information, a storage capacity for comprehensively storing the measured luminance distribution patterns of the plurality of light sources 6a is required. Such information can be limited to some extent by recording the sampled luminance distribution in the form of a look-up table (LUT) and obtaining an approximate value of luminance between samples by interpolation processing. However, a memory with a storage capacity corresponding to the degree of sampling is still required. In the process for obtaining the luminance distribution (for example, the luminance distribution T ₁ ) by combining the light from the plurality of light sources 6a, an operation based on the LUT and the algorithm for the complementary process is performed. However, the calculation capability required for such calculation is enormous. When a specific example is schematically shown with the example shown in FIG. 6, the luminance distributions T ₂ , T ₃ , T ₄ , and T ₅ of the light source 6 a are obtained based on the control pattern P. Sonouede, these luminance distribution _{T 2, T 3, T 4} , the luminance _T b of a predetermined position in the _{T 5, T c, T d} , based on _{T e,} a plurality of not necessarily the process of obtaining the luminance _{T a} in position Perform at the position. As a result, the luminance distribution T ₁ obtained by combining the luminance distributions T ₂ , T ₃ , T ₄ , and T ₅ is obtained. If you try to find the luminance distribution of the display region 21 in a manner similar mechanism for obtaining the luminance distribution T _1, the processing load is further enormous depending on the number of partial regions and the light source 6a.

  As described above, if strict local dimming is to be performed, an operation relating to the specification of the luminance distribution of the entire display area 21 with a huge processing load as described with reference to FIG. 6 is required. The LUT indicating the luminance distribution of each of the plurality of light sources 6a is obtained. Therefore, in the present embodiment, local dimming is performed with a simpler mechanism.

FIG. 7 is a graph showing the calculated luminance distribution Q of the four partial regions n, (n + 1), (n + 2), and (n + 3) by correcting the output gradation value according to this embodiment. FIG. 8 shows the calculated luminance distribution Q between the two partial areas n and (n + 1), the position of the pixel Pix from the boundary between the partial areas to the mth pixel Pix, and the farthest from the boundary among the pixels Pix from the boundary to the mth. It is a graph which shows an example of the relationship with the position of the ath pixel Pix from the direction. In the present embodiment, the light source control unit 102 determines the light emission amount of one light source 6a associated with the one partial area according to the luminance of light required in one partial area. Specifically, the light source control unit 102 outputs a drive signal for lighting the plurality of light sources 6a with a light emission amount that provides a luminance necessary for the output gradation value of the pixel Pix included in each of the plurality of partial regions. The luminance of each of the plurality of partial areas corresponding to the light emission amount indicated by the drive signal is uniquely determined for each partial area as indicated by the control pattern P shown in FIG. Here, in the present embodiment, regardless of the actual luminance distribution (for example, the luminance distributions T ₁ , T ₂ , T ₃ , T ₄ , T ₅ ), the light emission amounts corresponding to the drive signals related to the plurality of light sources 6a Is considered to be working.

  As illustrated by the control pattern P, the boundary may be visually recognized due to the luminance difference between the adjacent partial areas simply by individually controlling the light emission amounts of the plurality of light sources 6a. Therefore, in the present embodiment, the display control unit 101 performs the first correction and the second correction when the light emission amounts of the two light sources 6a associated with two adjacent partial areas are different. The target of the first correction is the pixel Pix of one partial region (first partial region) associated with the light source (first light source) 6a having a relatively large light emission amount. In the first correction, among the pixels Pix in the one partial region, the output gradation value of the pixel Pix in the range (first range) from the boundary to the position of the mth pixel is lowered. Here, the boundary means one partial region associated with the light source 6a having a relatively large light emission amount and the other partial region associated with the light source (second light source) 6a having a relatively small light emission amount. Indicates the boundary with (second partial area). The second correction target is the pixel Pix in the other partial region. In the second correction, among the pixels Pix in the other partial region, the output gradation value of the pixel Pix in the range (second range) from the boundary to the position of the mth pixel is increased. In the present embodiment, by correcting the output gradation values of the pixels Pix in the first range and the second range by the first correction and the second correction, as shown in the calculated luminance distribution Q of FIGS. 7 and 8, Irradiates a range from the position of the mth pixel Pix in one partial region (for example, the partial region (n + 1)) to the position of the mth pixel Pix in the other partial region (for example, the partial region n). It is possible to reproduce a state similar to that in which the luminance of light gradually changes between one partial region and the other partial region.

Specifically, the light emission amount of the light source 6a having a relatively small light emission amount is Ln, the light emission amount of the light source 6a having a relatively large light emission amount is L (n + 1), and the pixel Pix at a predetermined position is the first pixel. Assuming that the light emission amount of the first virtual light source or the second virtual light source that illuminates the a-th pixel Pix from the predetermined position is La. The display control unit 101 determines La based on Expression (1) using Expression (2). Here, the first virtual light source is a light source obtained by virtually changing the light emission amount of the light source 6a having a relatively large light emission amount. The second virtual light source is a light source obtained by virtually changing the light emission amount of the light source 6a having a relatively small light emission amount. The “virtual change” does not change the light emission amount itself of the light source 6a, but changes the output gradation value of the pixel Pix illuminated by the light source 6a to display the same as when the light emission amount is changed. Refers to obtaining output (brightness). The value of La determined by the display control unit 101 corresponds to the brightness reproduced by changing the output gradation value of the pixel Pix “corresponds to the position of the pixel Pix in the XY coordinate system shown in FIGS. The light emission amount of a virtual light source that is located at the position where the pixel Pix is illuminated is shown. The “predetermined position” is the position of the mth pixel Pix from the boundary and the position of the pixel Pix located on the light source 6a side where the light emission amount is relatively small. The “a-th pixel from a predetermined position” refers to the a-th pixel Pix when counted in the direction from the light source 6a side where the light emission amount is relatively small toward the light source 6a side where the light emission amount is relatively large.
A = a / 2m (1)
La = L (n + 1) − {L (n + 1) −Ln} × (2 × A ^ 3-3 × A ^ 2 + 1) (2)

  The display control unit 101 individually calculates the light emission amount (La) of the first virtual light source or the second virtual light source for all the pixels Pix located within the mth position across the boundary. When the curve or approximate curve connecting the light emission amounts (La) calculated for all the pixels Pix is connected to the light emission amounts of the respective partial areas in the range farther than the mth from the boundary, the calculated luminance distribution Q is obtained. Become.

The display control unit 101 corrects the luminance according to the determined value of La. Specifically, the display control unit 101 outputs an output floor before the second correction of the pixel Pix in the second range, that is, the pixel Pix at the position (a ≦ m) included in the other partial region (for example, the partial region n). When the tone value is P1, and the output gradation value after the second correction is P2, P2 is calculated by the following equation (9).
P2 = P1 × La / Ln (9)
La in Expression (9) satisfies Ln <La <(Ln + L (n + 1)) / 2. That is, the output gradation value after the second correction is such that the pixel Pix controlled by the output gradation value before the second correction exceeds the light emission amount (Ln) of the light source 6a with a relatively small light emission amount, and It is an output gradation value when illuminated by light from the second virtual light source that is lower than the light emission amount ((Ln + L (n + 1)) / 2) intermediate between the light emission amounts of the two light sources 6a.

  As a specific example, when P1: (R, G, B, W) = (0, 0, 0, 50) and La / Ln = 1.5, P2: (R, G, B , W) = (0, 0, 0, 75). As described above, the display control unit 101 corrects the output gradation value, thereby changing the luminance of the pixel Pix arranged at the position corresponding to the value of La to the light emission amount of the light source 6a having a relatively small light emission amount. The luminance can be the same as that when the luminance is higher than the luminance according to (Ln).

Further, the display control unit 101 outputs the output gradation before the first correction of the pixel Pix in the first range, that is, the pixel Pix at the position (a> m) included in one partial region (for example, the partial region (n + 1)). When the value is P3 and the output gradation value after the first correction is P4, P4 is calculated by the following equation (10).
P4 = P3 × La / L (n + 1) (10)
La in Expression (10) satisfies (Ln + L (n + 1)) / 2 <La <L (n + 1). That is, the output gradation value after the first correction is less than the light emission amount (L (n + 1)) of the light source 6a where the pixel Pix controlled by the output gradation value before the first correction has a relatively large light emission amount. And an output gradation value when illuminated by light from the first virtual light source that exceeds the light emission amount ((Ln + L (n + 1)) / 2) intermediate between the light emission amounts of the two light sources 6a.

  As a specific example, when P3: (R, G, B, W) = (0, 0, 0, 50) and La / L (n + 1) = 0.8, P4: (R, G, B, W) = (0, 0, 0, 40). As described above, the display control unit 101 corrects the output gradation value to change the luminance of the pixel Pix arranged at the position corresponding to the value of La to the light emission amount of the light source 6a having a relatively large light emission amount. The luminance can be the same as that when the luminance is lower than the luminance according to (L (n + 1)).

In the present embodiment, when the total number of pixels in the display area 21 is n ₁ (n ₁ is a natural number), n ₁ = 800 × 480. Further, when the number of pixels Pix arranged in the X direction or the Y direction in one partial region is n ₂ (n ₂ is a natural number), n ₂ = 100 or n ₂ = 120. Further, m (m is a natural number) in “mth pixel Pix from the boundary” is 8, for example. Therefore, n ₁ > n ₂ > m ≧ 1 is established. The illustrated values of n ₁ , n ₂ , and m are merely examples, and are not limited thereto, and can be appropriately changed within a range where n ₁ > n ₂ > m ≧ 1 is satisfied.

  The display control unit 101 increases the degree of correction for the output tone value of the pixel Pix closer to the boundary in the first correction and the second correction. For example, as shown in FIG. 8, within the range of the partial region n, the curve drawn by the calculated luminance distribution Q decreases from the light emission amount (Ln) of the light source 6a whose light emission amount is relatively smaller toward the boundary between the partial regions. The light emission amount (La) of the second virtual light source is calculated so as to approach the light emission amount (L (n + 1)) side of the light source 6a having a relatively large. In the range of the partial area (n + 1), the curve drawn by the calculated luminance distribution Q is relatively large as the distance between the partial areas approaches, and the light emission quantity is from the light emission quantity (L (n + 1)) of the light source 6a. The light emission amount (La) of the first virtual light source is calculated so as to approach the light emission amount (Ln) side of the relatively small light source 6a. In order to increase the degree of correction with respect to the output gradation value of the pixel Pix closer to the boundary in the first correction and the second correction, it is only necessary that m ≧ 2.

  The correction of the output gradation value has been described above by taking the combination of the partial region n and the partial region (n + 1) as an example. However, the display control unit 101 has the partial region (n + 1), the partial region (n + 2), and the partial region (n + 2). In the combination of the other two partial areas such as the partial area (n + 3), the output gradation value is corrected by the same mechanism.

  FIG. 9 is a schematic diagram illustrating an example of correction of output gradation values in the X direction and the Y direction. In the present embodiment, as illustrated in FIG. 4, a plurality of partial regions are arranged in the X direction and the Y direction. Therefore, the display control unit 101 corrects the output gradation value in both the X direction and the Y direction. Specifically, for example, as illustrated in FIG. 9, the display control unit 101 sets the partial area n and the partial area (n + 1) for the combination of two partial areas N and (N + 1) arranged in the Y direction. The output tone value is corrected by the same mechanism as the combination. Further, the display control unit 101 corrects the output gradation value for the combination of two partial areas n and (n + 1) arranged in the X direction. More specifically, with reference to FIG. 9, for example, the display control unit 101 sets the light emission amount of the light source 6a having a relatively small light emission amount to LN and the light emission amount of the light source 6a having a relatively large light emission amount. Let L (N + 1) be the light emission amount (Lb) of the second virtual light source that illuminates the b-th pixel Pix from the light source 6a side that is farther from the boundary among the mth pixels Pix within the boundary and has a relatively small light emission amount. , Lc). In other words, the boundary between the partial region N and the partial region (N + 1) is BN, the m-th pixel Pix from the boundary BN in the partial region N is the pixel PNm, and the boundary BN in the partial region (N + 1) is m When the pixel Pix is the pixel P (N + 1) m, the display control unit 101 is in the range from the position of the pixel PNm to the position of the pixel P (N + 1) m, and illuminates the bth pixel Pix from the pixel PNm. The light emission amount (Lb, Lc) of the second virtual light source is calculated. Here, Lb and Lc are light emission amounts of the second virtual light source of the pixel Pix located at the m-th (or m + 1-th) across the boundary between the partial region n and the partial region (n + 1). When the light emission amount Lb of the second virtual light source in the partial region n and the light emission amount Lc of the second virtual light source in the partial region (n + 1) are different from each other, the display control unit 101 has a relative light emission amount. Pixels Pix from the boundary to the other partial region associated with the second virtual light source having a relatively small amount of light emission among the pixels Pix of the one partial region associated with the second large virtual light source that is relatively large The first correction for lowering the output tone value is performed, and the second correction for increasing the output tone value of the pixels Pix from the boundary to the m-th pixel among the pixels Pix in the other partial region is performed. In the present embodiment, the display control unit 101 sets the light emission amount of the second virtual light source having a relatively small light emission amount to Ln, and the light emission amount of the second virtual light source having a relatively large light emission amount to L (n + 1). The light emission of the second virtual light source (or the first virtual light source) that illuminates the a-th pixel Pix from the light source 6a side that is farther from the boundary among the mth pixels Pix within the boundary and has a relatively small light emission amount. The amount (La) is calculated. In other words, the boundary between the partial region n and the partial region (n + 1) is the boundary Bn, the mth pixel Pix from the boundary Bn in the partial region n is the pixel Pnm, and the boundary Bn in the partial region (n + 1) is When the m-th pixel Pix is a pixel P (n + 1) m, the display control unit 101 is in a range from the position of the pixel Pnm to the position of the pixel P (n + 1) m, and illuminates the a-th pixel Pix from the pixel Pnm. The light emission amount (La) of the second virtual light source (or the first virtual light source) is calculated. Note that when the relative brightness relationship in the combination of the two partial areas N and (N + 1) is opposite, Lb and Lc are the light emission amounts of the first virtual light source. Also in this case, the first correction and the second correction are performed in the X direction.

  In the above description, after calculating the light emission amounts of the first virtual light source and the second virtual light source in the Y direction (for example, light emission amounts Lb and Lc), the light emission amounts of the first virtual light source and the second virtual light source in the X direction ( La) is calculated, but first, the light emission amounts of the first virtual light source and the second virtual light source are calculated for the X direction, and then the light emission amounts of the first virtual light source and the second virtual light source are calculated for the Y direction. May be.

As described above, according to the present embodiment, the amount of light emitted from one light source 6a associated with one partial area is determined according to the luminance of light required in one partial area, and each light source 6a luminance distribution (e.g., luminance distribution T _2, etc.) since the local dimming in the process does not depend on the luminance distribution by combining a luminance distribution of a plurality of light sources 6a (e.g., luminance distribution T ₁₎ calculation and according to the derivation of Resources related to maintaining the luminance distribution of each light source 6a can be eliminated. Therefore, local dimming can be realized with less burden. In addition, since the first correction and the second correction are performed, local dimming that makes it difficult to visually recognize the boundary can be realized.

  Further, when m ≧ 2, the degree of correction of the output gradation value of the pixel Pix closer to the boundary in the first correction and the second correction is increased, so that each of the two partial regions adjacent to each other across the boundary The luminance difference between the two light sources 6a corresponding to can be made more gradual. Therefore, it is possible to realize local dimming that makes it difficult to visually recognize the boundary.

  Further, by determining the light emission amount La of the first virtual light source or the second virtual light source based on the formula (1) based on the formula (1), 2 corresponding to each of the two partial regions adjacent to each other across the boundary. It is possible to formulate a process for reducing the luminance difference between the two light sources 6a. Therefore, local dimming can be realized with less burden and less visibility of the boundary.

(Modification)
Hereinafter, modifications of the embodiment according to the present invention will be described. In the description of the modification, the same components as those in the embodiment may be denoted by the same reference numerals and description thereof may be omitted.

FIG. 10 shows the calculated luminance distribution Q between two partial areas n and (n + 1), the position of the pixel Pix from the boundary between the partial areas to the mth pixel Pix, and the pixel Pix from the boundary far from the boundary. It is a graph which shows an example of the relationship with the position of the ath pixel Pix from the direction. In the modified example, the light emission amount of the light source 6a having a relatively small light emission amount is Ln, the light emission amount of the light source 6a having a relatively large light emission amount is L (n + 1), and the boundary among the pixels Pix within the mth from the boundary. If the light emission amount of the first virtual light source or the second virtual light source that illuminates the a-th pixel Pix from the light source 6a side that is far from the light source 6a side is La and the predetermined variable is Coef, display The control unit 101 employs any one of the equations (4) to (7) according to A which is the value indicated by the equation (3), determines the Coef, and uses the determined Coef to determine the equation (8 ), And formula (4) is adopted when A <1, formula (5) is adopted when 1 ≦ A <2, and formula (6) is adopted when 2 ≦ A <3. Adopting, when 3 ≦ A <4, the equation (7) is adopted. In other words, the boundary between the partial region n and the partial region (n + 1) is the boundary Bn, the mth pixel Pix from the boundary Bn in the partial region n is the pixel Pnm, and the boundary Bn in the partial region (n + 1) is If the mth pixel Pix is the pixel P (n + 1) m, the light emission amount (La) is in the range from the position of the pixel Pnm to the position of the pixel P (n + 1) m, and the ath pixel Pix from the pixel Pnm is The amount of light emitted from the first virtual light source or the second virtual light source to be illuminated.
A = a / (2m / 4) (3)
Coef = 0.5 × {−1 / 6 × (2.0−A−2.0) ^ 3} (4)
Coef = 0.5 * [1/6 * {3 * (2.0-A) ^ 3-6 * (2.0-A) ^ 2 + 4}] + {-1/6 * (3.0-A -2.0) ^ 3} (5)
Coef = 0.5 * [1/6 * {3 * (A-2.0) ^ 3-6 * (A-2.0) ^ 2 + 4}] + [1/6 * {3 * (3.0 -A) ^ 3-6 * (3.0-A) ^ 2 + 4}] + {-1/6 * (4.0-A-2.0) ^ 3} (6)
Coef = 0.5 × {−1 / 6 × (A−2.0−2.0) ^ 3} + [1/6 × {3 × (A−3.0) ^ 3-6 × (A− 3.0) ^ 2 + 4}] + [1/6 * {3 * (4.0-A) ^ 3-6 * (4.0-A) ^ 2 + 4}] + {-1/6 * (5. 0-A-2.0) ^ 3} (7)
La = L (n + 1) − {L (n + 1) −Ln} × Coef (8)

  FIG. 10 illustrates the value of A when m = 8, but this is an example and is not limited to this, and may vary depending on the value of m.

  As described above, according to the modification, the block boundary is {Ln + L (n + 1)} / 2, the value of the pixel Pix located at −m / 2 from the block boundary is Ln, and the value of the pixel Pix located at + m / 2 from the block boundary It is possible to connect Ln and L (n + 1) with a cubic spline curve with L (n + 1) as.

  The specific mechanism for calculating the curve connecting Ln and L (n + 1) is not limited to the above-described embodiment and modification examples, and can be changed as appropriate. For example, the display control unit 101 has Ln and L (n + 1) as variables, and determines the light emission amounts of the first virtual light source and the second virtual light source using a predetermined equation that defines a curve connecting Ln and L (n + 1). You may make it do. An LUT that defines the curve may be provided. In this case, local dimming can be realized with an LUT having a storage capacity that is significantly smaller than that of a conventional LUT showing the luminance distribution of a plurality of light sources 6a.

  In addition, other functions and effects brought about by the aspects described in the present embodiment, which are apparent from the description of the present specification, or can be appropriately conceived by those skilled in the art, are naturally understood to be brought about by the present invention. .

  Further, the present invention can be described as follows.

1. A plurality of light sources arranged along at least one direction;
n ₁ pixels includes a display region provided with a display unit for outputting the image is illuminated with light from said plurality of light sources,
A light source control unit that controls the operation of the light source based on the display output content of the display unit;
A display control unit that controls a part or all of output gradation values among the plurality of pixels based on a light emission amount of the light source,
The display area is divided into a plurality of partial areas associated with each of the plurality of light sources,
One partial region includes at least n ₂ pixels arranged along the one direction,
The light source control unit determines the light emission amount of one light source associated with the one partial area according to the luminance of light required in one partial area,
The display control unit is a first partial region associated with a first light source having a relatively large light emission amount when the light emission amounts of two light sources associated with two adjacent partial regions are different. Of the pixels in the partial area, the pixels in the first range from the boundary with the second partial area, which is the other partial area associated with the second light source having a relatively small light emission amount, to the position of the mth pixel. Second correction is performed to lower the output gradation value and to increase the output gradation value of the pixels in the second range from the boundary to the position of the mth pixel among the pixels of the second partial region. Make corrections
The output gradation value after the first correction is such that the pixel controlled by the output gradation value before the first correction is less than the light emission amount of the first light source having a relatively large light emission amount, and the two The output gradation value when illuminated with light from the first virtual light source that exceeds the light emission amount intermediate between the light emission amounts of the light sources,
The output gradation value after the second correction is such that the pixel controlled by the output gradation value before the second correction exceeds the light emission amount of the second light source with a relatively small light emission amount, and the two It is an output gradation value when illuminated by light from the second virtual light source that is less than the intermediate light emission amount of each light source,
n ₁ > n ₂ > m ≧ 1 display device.

2. m ≧ 2,
The display control unit increases the degree of correction with respect to an output gradation value of a pixel closer to the boundary in the first correction and the second correction. The display device described in 1.

3. The light emission amount of the second light source having a relatively small light emission amount is Ln, the light emission amount of the first light source having a relatively large light emission amount is L (n + 1), and the mth pixel in the first partial region. Of the first virtual light source or the second virtual light source that illuminates the a-th pixel from the m-th pixel of the second partial region in a range from the position of the second partial region to the position of the m-th pixel of the second partial region When the light emission amount is La, the display control unit determines La according to the equation (2) based on the equation (1). Or 2. The display device described in 1.
A = a / 2m (1)
La = L (n + 1) − {L (n + 1) −Ln} × (2 × A ^ 3-3 × A ^ 2 + 1) (2)

4). The light emission amount of the second light source having a relatively small light emission amount is Ln, the light emission amount of the first light source having a relatively large light emission amount is L (n + 1), and the mth pixel in the first partial region. Of the first virtual light source or the second virtual light source that illuminates the a-th pixel from the m-th pixel of the second partial region in a range from the position of the second partial region to the position of the m-th pixel of the second partial region When the light emission amount is La and the predetermined variable is Coef, the display control unit employs any one of formulas (4) to (7) according to A which is a value represented by formula (3). Coef is determined, and La is determined by Equation (8) using the determined Coef. Equation (4) is adopted when A <1, and Equation (5) is adopted when 1 ≦ A <2. Adopting, when 2 ≦ A <3, the equation (6) is adopted, and when 3 ≦ A <4, the equation (7) is adopted. 1. Or 2. The display device described in 1.
A = a / (2m / 4) (3)
Coef = 0.5 × {−1 / 6 × (2.0−A−2.0) ^ 3} (4)
Coef = 0.5 * [1/6 * {3 * (2.0-A) ^ 3-6 * (2.0-A) ^ 2 + 4}] + {-1/6 * (3.0-A -2.0) ^ 3} (5)
Coef = 0.5 * [1/6 * {3 * (A-2.0) ^ 3-6 * (A-2.0) ^ 2 + 4}] + [1/6 * {3 * (3.0 -A) ^ 3-6 * (3.0-A) ^ 2 + 4}] + {-1/6 * (4.0-A-2.0) ^ 3} (6)
Coef = 0.5 × {−1 / 6 × (A−2.0−2.0) ^ 3} + [1/6 × {3 × (A−3.0) ^ 3-6 × (A− 3.0) ^ 2 + 4}] + [1/6 * {3 * (4.0-A) ^ 3-6 * (4.0-A) ^ 2 + 4}] + {-1/6 * (5. 0-A-2.0) ^ 3} (7)
La = L (n + 1) − {L (n + 1) −Ln} × Coef (8)

5. When the output gradation value before the second correction of the pixels in the second range is P1, and the output gradation value after the second correction is P2, the display control unit sets P2 to the following equation: Calculated in (9),
When the output gradation value before the first correction of the pixels in the first range is P3 and the output gradation value after the first correction is P4, the display control unit sets P4 to the following equation: The display device according to 3, which is calculated in (10).
P2 = P1 × La / Ln (9)
P4 = P3 × La / L (n + 1) (10)

1 display device 2 display section 3 driven element 6 light unit 6a source 100 control unit 101 display control unit 102 light source control unit 76a black matrix 76b opening COM common electrode FG windshield M mirror P control pattern Pix pixel Q calculated luminance distribution _{T 1 , T 2, T 3, T} 4, T 5 luminance distribution _{T a, T b, T c} , T d, T e luminance Vpix subpixel

Claims (5)

A plurality of light sources arranged along at least one direction;
n ₁ pixels includes a display region provided with a display unit for outputting the image is illuminated with light from said plurality of light sources,
A light source control unit that controls the operation of the light source based on the display output content of the display unit;
A display control unit that controls a part or all of output gradation values among the plurality of pixels based on a light emission amount of the light source,
The display area is divided into a plurality of partial areas associated with each of the plurality of light sources,
One partial region includes at least n ₂ pixels arranged along the one direction,
The light source control unit determines the light emission amount of one light source associated with the one partial area according to the luminance of light required in one partial area,
The display control unit is a first partial region associated with a first light source having a relatively large light emission amount when the light emission amounts of two light sources associated with two adjacent partial regions are different. Of the pixels in the partial area, the pixels in the first range from the boundary with the second partial area, which is the other partial area associated with the second light source having a relatively small light emission amount, to the position of the mth pixel. Second correction is performed to lower the output gradation value and to increase the output gradation value of the pixels in the second range from the boundary to the position of the mth pixel among the pixels of the second partial region. Make corrections
The output gradation value after the first correction is such that the pixel controlled by the output gradation value before the first correction is less than the light emission amount of the first light source having a relatively large light emission amount, and the two The output gradation value when illuminated with light from the first virtual light source that exceeds the light emission amount intermediate between the light emission amounts of the light sources,
The output gradation value after the second correction is such that the pixel controlled by the output gradation value before the second correction exceeds the light emission amount of the second light source with a relatively small light emission amount, and the two It is an output gradation value when illuminated by light from the second virtual light source that is less than the intermediate light emission amount of each light source,
n ₁ > n ₂ > m ≧ 1 display device. m ≧ 2,
The display device according to claim 1, wherein the display control unit increases the degree of correction with respect to an output gradation value of a pixel closer to the boundary in the first correction and the second correction. The light emission amount of the second light source having a relatively small light emission amount is Ln, the light emission amount of the first light source having a relatively large light emission amount is L (n + 1), and the mth pixel in the first partial region. Of the first virtual light source or the second virtual light source that illuminates the a-th pixel from the m-th pixel of the second partial region in a range from the position of the second partial region to the position of the m-th pixel of the second partial region 3. The display device according to claim 1, wherein when the light emission amount is La, the display control unit determines La according to Formula (2) based on Formula (1).
A = a / 2m (1)
La = L (n + 1) − {L (n + 1) −Ln} × (2 × A ^ 3-3 × A ^ 2 + 1) (2) The light emission amount of the second light source having a relatively small light emission amount is Ln, the light emission amount of the first light source having a relatively large light emission amount is L (n + 1), and the mth pixel in the first partial region. Of the first virtual light source or the second virtual light source that illuminates the a-th pixel from the m-th pixel of the second partial region in a range from the position of the second partial region to the position of the m-th pixel of the second partial region When the light emission amount is La and the predetermined variable is Coef, the display control unit employs any one of formulas (4) to (7) according to A which is a value represented by formula (3). Coef is determined, and La is determined by Equation (8) using the determined Coef. Equation (4) is adopted when A <1, and Equation (5) is adopted when 1 ≦ A <2. Adopting, when 2 ≦ A <3, the equation (6) is adopted, and when 3 ≦ A <4, the equation (7) is adopted. The display device according to claim 1 or 2.
A = a / (2m / 4) (3)
Coef = 0.5 × {−1 / 6 × (2.0−A−2.0) ^ 3} (4)
Coef = 0.5 * [1/6 * {3 * (2.0-A) ^ 3-6 * (2.0-A) ^ 2 + 4}] + {-1/6 * (3.0-A -2.0) ^ 3} (5)
Coef = 0.5 * [1/6 * {3 * (A-2.0) ^ 3-6 * (A-2.0) ^ 2 + 4}] + [1/6 * {3 * (3.0 -A) ^ 3-6 * (3.0-A) ^ 2 + 4}] + {-1/6 * (4.0-A-2.0) ^ 3} (6)
Coef = 0.5 × {−1 / 6 × (A−2.0−2.0) ^ 3} + [1/6 × {3 × (A−3.0) ^ 3-6 × (A− 3.0) ^ 2 + 4}] + [1/6 * {3 * (4.0-A) ^ 3-6 * (4.0-A) ^ 2 + 4}] + {-1/6 * (5. 0-A-2.0) ^ 3} (7)
La = L (n + 1) − {L (n + 1) −Ln} × Coef (8) When the output gradation value before the second correction of the pixels in the second range is P1, and the output gradation value after the second correction is P2, the display control unit sets P2 to the following equation: Calculated in (9),
When the output gradation value before the first correction of the pixels in the first range is P3 and the output gradation value after the first correction is P4, the display control unit sets P4 to the following equation: The display device according to claim 3, which is calculated in (10).
P2 = P1 × La / Ln (9)
P4 = P3 × La / L (n + 1) (10)

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