Display device

A display device includes a display portion comprising pixels including a first pixel and a second pixel, a source driver for applying a pixel voltage to pixels through signal lines, and a control portion for controlling the source driver. The first and second pixels each include a first sub-pixel and a second sub-pixel. The first sub-pixel includes a light exit portion and a color filter for a first hue. The second sub-pixel includes a light exit portion and a color filter for a second hue. An area of the light exit portion of the first sub-pixel of the first pixel is smaller than that of the first sub-pixel of the second pixel. The control portion converts the video signal for the first sub-pixel into a brighter one. The source driver applies the pixel voltage to the first sub-pixel of the first pixel based on the video signal after conversion.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority from the Japanese Application JP 2013-185330 filed on Sep. 6, 2013, the content of which is hereby incorporated by reference into this application.

TECHNICAL FIELD

The present invention relates to a display device.

BACKGROUND

In general, a display device includes a spacer for maintaining an interval between a so-called thin film transistor (TFT) substrate and a so-called counter substrate opposed to the TFT substrate. Here, Japanese Patent Application Laid-open No. Hei 10-68955 discloses that the spacer is provided to a source electrode region of a TFT in order to prevent the spacer from reducing an aperture ratio.

SUMMARY

However, it is difficult to provide a spacer only to the above-mentioned source electrode region as pixel resolution is becoming higher in recent years. In this case, the spacer can be provided so as to cover a part of an aperture region of a pixel, but such placement causes a reduction in luminance, display unevenness, and the like.

The present invention has been made in view of the above-mentioned problem, and an object thereof is to provide a display device capable of reducing, for example, a reduction in luminance and display unevenness as described above.

In one general aspect, the present application describes a display device that includes a display portion in which a plurality of pixels comprising a first pixel and a second pixel are arranged in a matrix shape; a source driver for applying a pixel voltage to the plurality of pixels through a plurality of signal lines; and a control portion for controlling the source driver based on a video signal input from outside, the first pixel and the second pixel each comprising a first sub-pixel and a second sub-pixel. The first sub-pixel includes a light exit portion from which light exits; and a color filter for a first hue. The second sub-pixel includes the light exit portion; and a color filter for a second hue. An area of the light exit portion included in the first sub-pixel of the first pixel is smaller than an area of the light exit portion included in the first sub-pixel of the second pixel; the control portion converts, when the video signal input to the first sub-pixel of the first pixel is less than a predetermined value, the video signal input to the first sub-pixel of the first pixel into a video signal exhibiting a luminance higher than a luminance exhibited by the video signal input to the first sub-pixel; and the source driver applies the pixel voltage to the first sub-pixel of the first pixel based on the video signal after conversion.

The above general aspect may include one or more of the following features. An area of the light exit portion included in the second sub-pixel of the first pixel may be substantially equal to an area of the light exit portion included in the second sub-pixel of the second pixel.

The first pixel and the second pixel each may further include a third sub-pixel different from the first sub-pixel and the second sub-pixel. The third sub-pixel may further include a color filter for a third hue different from the first hue and the second hue. The control portion may convert, when the video signal input to the first sub-pixel of the first pixel after the conversion exceeds the predetermined value, the respective video signals input to the second sub-pixel and the third sub-pixel of the first pixel into respective video signals exhibiting luminances higher than luminances exhibited by the respective video signals input to the second sub-pixel and the third sub-pixel.

The control portion may convert the respective video signals input to the second sub-pixel and the third sub-pixel of the first pixel based on a relationship between the video signal exceeding the predetermined value and the predetermined value.

The control portion may convert, when one of the video signals input to the second sub-pixel and the third sub-pixel of the first pixel after the conversion exceeds a predetermined value, the other of the video signals input to the second sub-pixel and the third sub-pixel into a video signal exhibiting a luminance higher than a luminance exhibited by the other of the video signals.

The control portion may convert the other of the video signals input to the second sub-pixel and the third sub-pixel based on a relationship between the one of the video signals input to the second sub-pixel and the third sub-pixel and the predetermined value.

The control portion may convert, based on a ratio of visibilities of the color filters for the first hue, the second hue, and the third hue, the respective video signals input to the second sub-pixel and the third sub-pixel of the first pixel into respective video signals exhibiting the luminances higher than the luminances exhibited by the respective video signals input to the second sub-pixel and the third sub-pixel.

The first sub-pixel of the first pixel may further include an interference portion for inhibiting the light from exiting. The interference portion may cause the area of the light exit portion of the first sub-pixel of the first pixel to be smaller than the area of the light exit portion of the first sub-pixel of the second pixel.

The first hue may be blue.

The display device may further include a first substrate and a second substrate. The interference portion may be a spacer placed between the first substrate and the second substrate.

The interference portion may be a sensor.

In another general aspect, the display device of the present application includes a display portion in which a plurality of pixels comprising a first pixel and a second pixel are arranged in a matrix shape; a source driver for applying a pixel voltage to the plurality of pixels through a plurality of signal lines; and a control portion for controlling the source driver based on a video signal input from outside, the first pixel and the second pixel each comprising a first sub-pixel and a second sub-pixel. The first sub-pixel includes a light exit portion from which light exits; and a color filter for a first hue. The second sub-pixel includes the light exit portion; and a color filter for a second hue. An area of the light exit portion included in the first sub-pixel of the first pixel is smaller than an area of the light exit portion included in the first sub-pixel of the second pixel; the control portion converts, when the video signal exhibiting a fixed luminance less than a first predetermined value is input from the outside to the first sub-pixel included in each of the first pixel and the second pixel, the video signal input to the first sub-pixel of the first pixel into a video signal exhibiting a luminance higher than a luminance exhibited by the video signal input to the first sub-pixel of the second pixel; and the source driver applies the pixel voltage to the first sub-pixel of the first pixel based on the video signal after conversion.

The above another general aspect may include one or more of the following features. An area of the light exit portion included in the second sub-pixel of the first pixel may be substantially equal to an area of the light exit portion included in the second sub-pixel of the second pixel. The control portion may convert, when the video signal after the conversion which is input to the first sub-pixel of the first pixel is the video signal exhibiting a luminance of the first predetermined value and when the video signal exhibiting a fixed luminance less than a second predetermined value is input to each of the second sub-pixels included in the first pixel and the second pixel, the video signal input to the second sub-pixel of the first pixel into a video signal exhibiting a luminance higher than a luminance exhibited by the video signal input to the second sub-pixel of the second pixel; and the source driver applies the pixel voltage to the second sub-pixel of the first pixel based on the video signal after the conversion.

DETAILED DESCRIPTION

FIG. 1is a schematic diagram illustrating a display device100according to an embodiment of the present application. As illustrated inFIG. 1, a display device100includes, for example, a TFT substrate101and a filter substrate. On the TFT substrate101, thin film transistors (TFTs) and the like (not shown) are formed. The filter substrate is opposed to the TFT substrate101and is provided with color filters (not shown). The display device100also includes a liquid crystal layer (not shown) and a backlight unit103. The liquid crystal layer is sealed in a region sandwiched between the TFT substrate101and the color filter substrate102. The backlight unit103is provided on the TFT substrate101so as to be held in contact with a surface opposite to the side on which the filter substrate is provided. Note that, an outline of the display device100illustrated inFIG. 1is merely an example, and this embodiment is not limited thereto.

FIG. 2is a conceptual diagram of a pixel circuit formed on the TFT substrate101illustrated inFIG. 1. As illustrated inFIG. 2, the display device100includes, for example, a position information retaining portion200, a control portion201, a timing generation portion202, a gate driver203, a source driver204, and a panel205. Note that, the position information retaining portion200may be provided outside the display device100.

The position information retaining portion200retains position information of a sub-pixel211in which a spacer described later is placed as illustrated inFIG. 3. Specifically, for example, the position information retaining portion200retains coordinate information of the sub-pixel211having the spacer placed therein in horizontal and vertical directions on the panel205.

The control portion201includes a video signal selection portion206and a video signal conversion portion207. The control portion201controls the source driver204based on a video signal input from an external device.

The video signal selection portion206selects the video signals corresponding to a pixel210including the sub-pixel211in which the spacer is placed from among the video signals corresponding to one frame based on the positioninformation retained by the position information retaining portion200. Specifically, for example, the video signal selection portion206selects, from among the video signals corresponding to one frame, the video signal corresponding to a given sub-pixel211at coordinates retained by the position information retaining portion200and the video signal corresponding to another sub-pixel211included in one pixel210together with the given sub-pixel211.

The video signal conversion portion207converts, for example, a given video signal selected by the video signal selection portion206into another video signal exhibiting a luminance higher than a luminance exhibited by the given video signal. The video signal conversion portion207is described later in detail.

The timing generation portion202controls timings of the gate driver203and the source driver204described later. Specifically, the timing generation portion202controls the gate driver203by outputting a gate driver203control signal to the gate driver203based on a resolution of the input video signal. Further, the timing generation portion202controls the source driver204by outputting a source driver204control signal to the source driver204based on the resolution of the input video signal.

In the panel205, a plurality of gate lines208are arranged, and the gate lines208are connected to the gate driver203. Further, in the panel205, a plurality of video signal lines209are arranged so as to intersect the gate lines208, and the video signal lines209are connected to the source driver204. In addition, the panel205includes the pixels210segmented by the gate lines208and the video signal lines209in a matrix shape, and the pixels210each include a plurality of sub-pixels211. A TFT212, a pixel electrode213, an opposing electrode (not shown), and a color filter (not shown) are arranged in each of the sub-pixels211. The TFT212has a gate connected to the gate line208, and has a source and a drain one of which is connected to the video signal line209and the other of which is connected to the pixel electrode213.

The gate driver203includes a plurality of basic circuits (not shown) corresponding to a plurality of gate lines208on a one-to-one basis. Note that, each of the basic circuits includes a plurality of TFTs and capacitors, and outputs, to the corresponding gate line208, a gate signal that has a high voltage in a corresponding gate scanning period (signal high period) and a low voltage in the remaining period (signal low period) during one frame period based on the video signal.

The source driver204includes a plurality of basic circuits (not shown) corresponding to a plurality of video signal lines209on a one-to-one basis. Each of the basic circuits includes a plurality of TFTs and capacitors, and applies a pixel voltage to each of the pixels210based on the video signal controlled by the control portion201through the plurality of video signal lines209.

Next, a description is made of an outline of an operation performed by the pixel circuit having the above-mentioned configuration. The gate driver203outputs the gate signal to the gate of the TFT212through the gate line208. In addition, the source driver204supplies a voltage of the video signal to the TFT212, to which the gate signal is output, through the video signal line209based on a source driver control signal. Then, the voltage of the video signal is applied to the pixel electrode213through the TFT212. In this case, a potential difference occurs between the pixel electrode213and the opposing electrode.

The source driver204controls the potential difference, to thereby control alignment of a liquid crystal layer (not shown) inserted between the pixel electrode213and an opposing electrode412. Here, because light is guided into the liquid crystal layer from the backlight unit103, by controlling the alignment or the like of the liquid crystal layer as described above, a quantity of the light from the backlight unit103is adjusted to display an image as a result.

Next, with reference toFIG. 3, a description is made of a plan view illustrating a schematic layout of the panel205. As illustrated inFIG. 3, the panel205includes a plurality of pixels210including the first to third sub-pixels211arranged in a matrix shape. Specifically, for example, the sub-pixels211are arranged by being segmented in a matrix shape by the plurality of gate lines208and the plurality of video signal lines209. The panel205includes the pixels210each including the first to third sub-pixels211on which color filters for hues different from one another are arranged with overlaps in a light exit portions401. The light exit portion401and the color filter are described later. Note that, the number of sub-pixels211included in one pixel210is not limited to three, and may be one, two, four, or greater.

Each of the sub-pixels211includes the TFT212. Specifically, for example, each of the sub-pixels211has the TFT212in the vicinity of an intersection of the gate line208and the video signal line209. Further, the gate of the TFT212is connected to the gate line208, and one of the source and the drain is connected to the video signal line209, while the other is connected to the pixel electrode213through a drain electrode300.

Further, the panel205includes one spacer301for a plurality of sub-pixels211. For example, as illustrated inFIG. 3, one sub-pixel211of twenty-seven sub-pixels211includes the spacer301, and is placed with an overlap with a region that is the light exit portion401if the spacer301is not placed.

Note that, the spacers placed in the panel205are not limited to ones having the same size, and spacers different in size may be placed. Specifically, for example, some of the spacers301may be set large and each placed with an overlap with the region that is the light exit portion401if the spacer301is not placed, while the other spacers may be set small and each placed so as not to change an area of the light exit portion401.

Next, with reference toFIG. 4AandFIG. 4B, a description is made of sectional views of the panel205.FIG. 4Ais a view illustrating a cross-section taken along the line III-III ofFIG. 3, and illustrates a cross-section of a region in which the TFTs212of one pixel210having the spacer301placed therein are arranged. In the same manner,FIG. 4Bis a view illustrating a cross-section taken along the line III′-III′ ofFIG. 3, and illustrates a cross-section of a region in which the TFTs212of one pixel210having no spacer301placed therein are arranged. As illustrated inFIG. 4A, the panel205includes the TFT substrate101, a color filter substrate102, and a liquid crystal layer400placed between the TFT substrate101and the color filter substrate102.

First, a description is made of the light exit portion401and a boundary portion402. Each of the sub-pixels211includes the light exit portion401and the boundary portion402. The light exit portion401is a region in which any one of a red color filter403, a green color filter404, and a blue color filter405is placed in the color filter substrate102, a light shielding member such as the spacer301is not placed, and light from the backlight unit103transmits toward a display surface side. On the other hand, the boundary portion402is a region in which a light shielding layer406or the spacer301is placed.

Next, a description is made of an example of a cross-section of the TFT substrate101. The TFT substrate101includes: a first substrate411; and the gate line208, the video signal line209, the drain electrode300, the pixel electrode213, a first alignment layer408, a gate insulating layer409, and a semiconductor layer410, which are arranged on the first substrate411. In the region of the light exit portion401included in each of the sub-pixels211, the gate insulating layer409, the pixel electrode213, and the first alignment layer408are mainly placed on the TFT substrate101in the stated order on the color filter substrate102side with respect to the first substrate411. On the other hand, the TFT212and the first alignment layer408are placed on the color filter substrate102side with respect to the first substrate411in the region in which the light shielding layer406is placed on the color filter substrate102side within the boundary portion402of the TFT substrate101. Further, the TFT212includes the gate line208, the gate insulating layer409, the semiconductor layer410, the video signal line209, and the drain electrode300.

Next, a description is made of an example of a cross-section of the color filter substrate102. The color filter substrate102includes a second substrate407, the color filters403,404, and405, the light shielding layer406, the opposing electrode412, a second alignment layer413, and the spacer301. In the region of the light exit portion401included in each of the sub-pixels211, the color filters403,404, and405, the opposing electrode412, and the second alignment layer413are placed on the color filter substrate102in the stated order on the TFT substrate101side. Further, the color filter includes the red color filter403, the green color filter404, and the blue color filter405.

Note that, in the embodiment illustrated inFIG. 4AandFIG. 4B, the color filters403,404, and405represent color filters for hues of red, green, and blue, respectively, but the hues of the color filters included in one pixel210are not limited to the combination of red, green, and blue. The hues of the color filters included in one pixel210may include a combination of four colors such as red, green, blue, and white or a combination of red, green, blue, and yellow and other such combination.

Further, in the region in which the light shielding layer406is placed within the boundary portion402of each of the sub-pixels211, the light shielding layer406, the opposing electrode412, and the second alignment layer413are placed in the stated order on the TFT substrate101side with respect to the second substrate407. Further, in the boundary portion402in which the spacer301is placed among the boundary portions402of each of the sub-pixels211, the light shielding layer406and any one of the color filters403,404, and405are placed on the TFT substrate101side with respect to the second substrate407. Further, the spacer301, the opposing electrode412, and the second alignment layer413are placed in the stated order with overlaps with the light shielding layer406and the any one of color filters403,404, and405.

The spacer301is placed, for one sub-pixel211of the plurality of sub-pixels211, so as to be overlapped with the region that is the light exit portion401if the spacer301is not placed. For that reason, the area of the light exit portion401included in the sub-pixel211having the spacer301placed therein is smaller than the area of the light exit portion401included in the sub-pixel211having no spacer301therein. Note that, the light exit portions401included in the second sub-pixel211and the third sub-pixel211that have no spacer301therein have substantially the same area.

Note that, it is desired that the spacer301be placed in the sub-pixel211in which the color filter for the hue having the lowest visibility among the color filters for a plurality of hues is placed. In this case, the spacer301is placed so as to be overlapped with the light exit portion401of the sub-pixel211in which the color filter for the hue having the lowest visibility among the color filters for the respective hues different in visibility is placed, to thereby be able to alleviate a reduction in luminance caused by the spacer301.

For example, in the embodiment of the present application, a visibility ratio of the respective colors of red, green, and blue is approximately blue:red:green=1.1:3:5, and the visibility of light exiting from the light exit portion401through the blue color filter405is the lowest among the color filters403,404, and405for the respective colors of red, green, and blue. Therefore, in a case where the spacer301is placed so as to be overlapped with the region of the blue sub-pixel211in which the light shielding member is not placed, the reduction in the luminance of the pixel210can be alleviated compared to a case where the spacer301is placed so as to be overlapped with the region of the red or green sub-pixel211in which the light shielding member is not placed. Note that, in the following description, the first sub-pixel211is set as the sub-pixel211in which the spacer301is placed and the light exit portion401has a smaller area, and the second and third sub-pixels211are each set as the sub-pixel211having no spacer301therein.

Specifically, as illustrated inFIG. 4A, the spacer301is placed so as to be overlapped with the region that is the light exit portion401if the spacer301illustrated inFIG. 4Bis not placed. Further, the spacer301is placed in the sub-pixel211including the blue color filter405among the sub-pixels211in which the color filters403,404, and405for red, green, and blue, respectively, are placed. Note that, as illustrated inFIG. 4B, a plane and a cross-section of the blue sub-pixel211having no spacer301therein are equivalent to planes and cross-sections of the sub-pixels211in which the red and green color filters403and404are placed except for the hues of the color filters. Note that, the first and second alignment layers408and413, the gate insulating layer409, the polarizing plate, the light shielding layer406, the color filters403,404, and405, and the liquid crystal layer400are equivalent to those according to the prior art, and hence descriptions thereof are omitted.

Next, with reference toFIG. 5, descriptions are made of components of the video signal conversion portion207and operations of the respective components. The video signal conversion portion207includes a conversion ratio retaining portion500, a visibility ratio retaining portion501, a predetermined value retaining portion502, a lapse information retaining portion503, a predetermined value conversion portion504, a difference calculation portion505, a determination portion506, and an amplification portion507.

The conversion ratio retaining portion500retains a ratio by which the area of the light exit portion401is reduced by having the spacer301placed therein, in other words, a ratio of the area of the light exit portion401(hereinafter referred to as “light exit area ratio”). Specifically, for example, assuming that the area of the light exit portion401of the sub-pixel211having no spacer301therein is100while the area of the light exit portion401of the sub-pixel211having the spacer301placed therein is 80, the conversion ratio retaining portion500retains a light exit area ratio of 80%. Note that, the conversion ratio retaining portion500may individually retain the light exit area ratios of the respective sub-pixels211of the plurality of sub-pixels211having the spacer301placed therein, or may retain the light exit area ratio common to all the sub-pixels211.

The visibility ratio retaining portion501retains a ratio of the visibility (hereinafter referred to as “visibility ratio”) of the light exiting from the light exit portion401through each color filter. Specifically, for example, in a case where the red, green, and blue color filters403,404, and405are placed in the respective sub-pixels211included in one pixel210, the visibility ratio retaining portion501retains the visibility ratio of blue:red:green=1.1:3:5.

The predetermined value retaining portion502retains a predetermined value serving as an upper limit to which the source driver204can control each of the video signals corresponding to the respective sub-pixels211included in one pixel210. For example, in a case where one pixel210includes the first to third sub-pixels211, the predetermined value retaining portion502retains first to third predetermined values corresponding thereto, respectively. Note that, in a case where one pixel210includes one, two, four, or more sub-pixels211, the predetermined values corresponding thereto on a one-to-one basis are retained. Specifically, for example, each video signal has a range of 0 to 255 gray level in an exemplary case where one pixel210includes three sub-pixels211of red, green, and blue and each video signal corresponding to each of the sub-pixels211is an 8-bit signal. For that reason, the predetermined values of first to third video signals are all 255 gray level. Note that, the predetermined value of the video signal may differ depending on the color. For example, the predetermined values of red and blue video signals may be 32 gray level, and the predetermined value of a green video signal may be 64 gray level.

The lapse information retaining portion503retains: the respective video signals input to the respective sub-pixels211included in one pixel210; and information (hereinafter referred to as “color information”) relating to a combination of the hues of the color filters placed in the respective sub-pixels211. Specifically, for example, the lapse information retaining portion503retains each video signal and the color information corresponding to the video signal having a value less than the predetermined value in each process in which the amplification portion507described later performs amplification. In other words, the lapse information retaining portion503temporarily saves each video signal and the color information that change in each process. Further, a specific example of an operation of the lapse information retaining portion503is described later.

For example, when the determination portion506described later determines that the first to third video signals exceed the predetermined values, the predetermined value conversion portion504converts the video signals that exceed the predetermined values into the predetermined values of the first to third video signals corresponding thereto, respectively. Specifically, in a case where the blue video signal after conversion performed by the amplification portion507described later is 315 gray level and the predetermined value of the blue video signal is 255 gray level, the predetermined value conversion portion504converts the blue video signal into 255 gray level.

For example, in a case where the predetermined value conversion portion504converts the first to third video signals into the predetermined values, the difference calculation portion505calculates a difference between values of the video signals exceeding the first to third predetermined values and the first to third predetermined values corresponding thereto, respectively. For example, the difference calculation portion505calculates the difference of 60 gray level in the above-mentioned example in which the blue video signal after the conversion performed by the amplification portion507described later is 315 gray level and the predetermined value of the blue video signal is 255 gray level.

The determination portion506determines whether or not the respective video signals corresponding to the sub-pixels211of the respective colors, which have been converted by the amplification portion507described later, exceed the respective predetermined values. Specifically, for example, in a case where the blue video signal after the conversion performed by the amplification portion507is 300 gray level and the predetermined value of the blue video signal is 255 gray level, the determination portion506determines that the blue video signal after the conversion exceeds the predetermined value of the blue video signal.

The amplification portion507amplifies the luminance exhibited by the input video signal. Specifically, for example, the amplification portion507converts the video signal selected by the video signal selection portion206into the video signal exhibiting the luminance higher than the luminance exhibited by the selected video signal. In this case, the amplification portion507converts the video signal based on the light exit area ratio, the visibility ratio, a calculation result obtained by the difference calculation portion505, or the color information retained by the lapse information retaining portion503. Although the information used when the amplification portion507converts the video signal differs depending on the situation, a specific example of the conversion of the video signal performed by the amplification portion507in each situation is described below with reference toFIG. 6.

FIG. 6shows each video signal corresponding to each of the sub-pixels211and the color information, which are retained by the lapse information retaining portion503, in each process in which the amplification portion507amplifies the first to third video signals corresponding to the first to third sub-pixels211included in one pixel210, respectively. Note that, in order to describe the above-mentioned specific example, it is assumed that one pixel210includes the first to third sub-pixels211, the blue color filter405is placed in the first sub-pixel211, the red color filter403is placed in the second sub-pixel211, and the green color filter404is placed in the third sub-pixel211. Further, it is assumed that the blue sub-pixel211has the spacer301placed therein, and the light exit area ratio is 80%. Further, it is assumed that the visibility ratio is blue:red:green=1.1:3:5. Further, it is assumed that the video signals selected by the video signal selection portion206are (blue, red, green)=(252,250,100) as shown in the second row ofFIG. 6, and the predetermined values of the red, green, and blue video signals are all 255 gray level.

In addition, it is assumed that the video signal is directly proportional to the luminance, in other words, a γ characteristic representing a correlation between the video signal and the luminance is 1. The following description is made on the above-mentioned assumptions.

First, when the video signal selection portion206selects the respective video signals corresponding to one pixel210, the amplification portion507converts the video signal corresponding to the first sub-pixel211having the spacer301placed therein among the respective video signals (first processing). In this case, based on the light exit area ratio, the amplification portion507converts the video signal into the first video signal exhibiting the luminance higher than the luminance exhibited by the first video signal before the first processing corresponding to the first sub-pixel211. That is, the video signal is converted so that the luminance of the sub-pixel211having the spacer301placed therein is substantially the same as the luminance exhibited when the first video signal before the first processing is input to the sub-pixel211having no spacer301placed therein. By thus performing the conversion, the amplification portion507compensates the reduction in the luminance of the sub-pixel211caused by the presence of the spacer301.

In the above-mentioned specific example, the amplification portion507converts the blue video signal of 252 gray level based on the light exit area ratio 80%. That is, the amplification portion507converts the video signal into the video signal of 315 gray level obtained by dividing the video signal of 252 gray level by 0.8. Note that, the amplification portion507does not convert the red or green video signal in the first processing. Therefore, as shown inFIG. 6, the lapse information retaining portion503after the first processing retains the respective video signals of (blue, red, green)=(315, 250, 100). Note that, as described later with reference to a flowchart, after the subsequent determination performed by the determination portion506, before a second processing, the predetermined value conversion portion504converts the blue video signal of 315 gray level, which exceeds the predetermined value after the first processing, into the predetermined value of the blue video signal that is 255 gray level.

Further, in the above-mentioned specific example, the determination portion506determines that the blue video signal exceeds the predetermined value of the blue video signal, and hence the lapse information retaining portion503deletes the information indicating blue from the color information indicating blue, red, and green retained from an initial state. Therefore, as shown inFIG. 6, the lapse information retaining portion503after the first processing retains the color information indicating red and green.

Subsequently, the determination portion506performs determination for the first video signal corresponding to the first sub-pixel211after the first processing, and when it is determined by the determination portion506that the first video signal corresponding to the first sub-pixel211after the first processing exceeds the predetermined value, the amplification portion507converts the second and third video signals corresponding to the second and third sub-pixels211into the video signals exhibiting the luminance higher than the luminances exhibited by the second and third video signals (second processing). In this case, the amplification portion507converts the second and third video signals based on the visibility ratio and a relationship between the first video signal after the conversion performed in the first processing and a first predetermined value.

Specifically, for example, the amplification portion507evenly divides the luminance indicated by the difference between the first predetermined value and the first video signal after the first processing by the number of sub-pixels211other than the first sub-pixel211. The video signals to be input to the sub-pixels211other than the first sub-pixel211are converted so that the luminances of the sub-pixels211other than the first sub-pixel211are each increased so as to correspond to the evenly-divided luminance. By this conversion, the reduction in the luminance caused by the presence of the spacer301can be compensated in units of the pixels210even when the luminance of the pixel210cannot be compensated only by converting the first video signal.

Note that, the description is made of the case where the difference between the first predetermined value and the first video signal is evenly divided, but the present invention is not limited to the case where the difference is evenly divided, and the luminance of a specific sub-pixel may be preferentially amplified. For example, in a case where one pixel includes the sub-pixels of the four colors of red, green, blue, and white, when the above-mentioned second processing is performed, only the sub-pixel of white may be increased in luminance by an amount of the luminance indicated by the difference between the blue video signal exceeding the predetermined value and the predetermined value. In this case, it is possible to alleviate a change in the hue compared to the case of increasing the luminances exhibited by the red and green video signals. Note that, when the determination portion506determines that the predetermined value is not exceeded, the second processing and a third processing described later are not performed.

In the above-mentioned specific example, the amplification portion507converts the red video signal of 250 gray level and the green video signal of 100 gray level. In this case, the difference between the blue video signal of 315 gray level and the first predetermined value of 255 is 60 gray level, and based on the amount of the luminance exhibited by the blue video signal of 60 gray level, the luminance exhibited by the red video signal of 250 gray level and the luminance exhibited by the green video signal of 100 gray level are amplified. At this time, in order to evenly amplify the luminances of the red sub-pixel211and the green sub-pixel211, the amplification portion507adds the evenly-divided luminance exhibited by the blue video signal of 60 gray level to the luminances of the red and green sub-pixels211.

Here, the visibility ratio of red and blue is red:blue=3:1.1, and hence the luminance of half the luminance exhibited by the blue video signal of 60 gray level corresponds to the luminance exhibited by the red video signal of 11 gray level. Therefore, the amplification portion507converts the red video signal of 250 gray level into 261 gray level. In the same manner, the visibility ratio of green and blue is green:blue=5:1.1, and hence the luminance of half the luminance exhibited by the blue video signal of 60 gray level corresponds to the luminance exhibited by the green video signal of 6.6 gray level. Here, a gray level takes an integer value, and hence the amplification portion507performs round-off or the like as appropriate. For that reason, the amplification portion507converts the green video signal of 100 gray level into 107 gray level. Therefore, as shown inFIG. 6, the respective video signals after the second processing are (blue, red, green)=(255, 261, 107). Note that, as described later with reference to a flowchart, after the subsequent determination performed by the determination portion506, before the third processing, the predetermined value conversion portion504converts the red video signal of 261 gray level, which exceeds the predetermined value after the second processing, into the predetermined value of the red video signal that is 255 gray level.

Further, in the above-mentioned specific example, the determination portion506determines that the red video signal exceeds the predetermined value of the red video signal, and hence the lapse information retaining portion503deletes the information indicating red from the color information indicating red and green retained after the first processing. Therefore, as shown inFIG. 6, the lapse information retaining portion503after the second processing retains the color information indicating green.

Subsequently, the determination portion506performs determination for the second and third video signals after the second processing, and when it is determined by the determination portion506that one of the second and third video signals exceeds the second or third predetermined value, the amplification portion507converts the other video signal into the video signal exhibiting the luminance higher than the luminance exhibited by the other video signal (third processing). In this case, the amplification portion507converts the second or third video signal based on a relationship between the second or third video signal after the conversion performed in the second processing and the second or third predetermined value, the visibility ratio, and the color information retained by the lapse information retaining portion503. Note that, when the determination portion506determines that both the second and third video signals exceed the predetermined values or when the determination portion506determines that neither the second nor third video signal exceeds the predetermined value, the third processing is not performed.

In the above-mentioned specific example, the difference between the red video signal of 261 gray level and the predetermined value of the red video signal of 255 is 6 gray level, and the visibility ratio of red and green is red:green=3:5, and hence the luminance exhibited by the red video signal of 6 gray level corresponds to the luminance exhibited by the green video signal of 3.6 gray level. Here, the gray level takes an integer value, and hence the amplification portion507performs round-off or the like as appropriate, while the lapse information retaining portion503retains the color information indicating green, and hence the green video signal of 107 gray level is converted into 111 gray level. Therefore, as shown inFIG. 6, the respective video signals after the third processing are (blue, red, green)=(255, 255, 111).

Note that, when there is a video signal exceeding the predetermined value after the third processing, the predetermined value conversion portion504converts the video signal exceeding the predetermined value into the predetermined value. In the above-mentioned specific example, the green video signal is 111 gray level and does not exceed the predetermined value of the green video signal of 255, and hence the predetermined value conversion portion504does not convert the green video signal. Therefore, the source driver uses the video signals of (blue, red, green)=(255, 255, 111) after the conversion to apply the pixel voltage to each of the sub-pixels included in one pixel selected by the video signal selection portion206.

Next, with reference toFIG. 7andFIG. 8, an operation of the video signal conversion portion207is described by using the same specific example as described above. First, the video signals corresponding to one frame are input to the video signal selection portion206from, for example, the external device (S701).

Subsequently, based on the position information retained by the position information retaining portion200, the video signal selection portion206selects the video signals corresponding to the pixel210including the sub-pixel211having the spacer301placed therein from among the video signals corresponding to one frame (S702). In the above-mentioned specific example, the video signal selection portion206selects the video signals of (blue, red, green)=(252, 250, 100) corresponding to one pixel. Note that, the video signals that are not selected are output to the source driver204without any change from the state input from the external device (S712).

Subsequently, the lapse information retaining portion503retains the color information relating to the combination of colors of the color filters placed in the respective sub-pixels211included in one pixel210(S703). In the above-mentioned specific example, the color information relating to the combination of red, green, and blue is retained.

Subsequently, based on the light exit area ratio, the amplification portion507converts the first video signal corresponding to the first sub-pixel211having the spacer301placed therein among the video signals selectedby the video signal selection portion206(S704). In the above-mentioned specific example, the amplification portion507converts the blue video signal of 252 gray level into the blue video signal of 315 gray level based on the light exit area ratio of 80%.

Subsequently, the determination portion506determines whether or not the video signal converted by the amplification portion507in S704exceeds the predetermined value (S705). When the video signal after the conversion exceeds the predetermined value, the procedure advances to S706, and otherwise, the procedure advances to S712. In the above-mentioned specific example, 315 gray level are larger than 255 gray level, and hence the determination portion506determines that the video signal after the conversion exceeds the predetermined value. Note that, when it is determined in S705that the first video signal after the conversion does not exceed the first predetermined value, the first to third video signals are output to the source driver204(S712).

Subsequently, when the determination portion506determines in S705that the first video signal after the conversion exceeds the first predetermined value, the lapse information retaining portion503deletes the color information on the color filter placed in the sub-pixel211corresponding to the first video signal in S705(S706). In the above-mentioned specific example, the blue video signal becomes saturated, and hence the lapse information retaining portion503deletes the color information indicating blue from the color information indicating red, green, and blue. As a result, the lapse information retaining portion503retains the color information indicating red and green.

Subsequently, the predetermined value conversion portion504converts the first video signal that exceeds the predetermined value into the first predetermined value (S707). In the above-mentioned specific example, the determination portion506determines in S705that the blue video signal exceeds the predetermined value of the blue video signal, and hence the predetermined value conversion portion504converts the blue video signal of 315 gray level into the predetermined value of the blue video signal that is 255 gray level.

Subsequently, the difference calculation portion505calculates the difference between the first video signal exceeding the first predetermined value before being converted by the predetermined value conversion portion504in S707and the first predetermined value (S708). In the specific example, the difference calculation portion505calculates the difference of 60 gray level between the blue video signal of 315 gray level and the predetermined value of the blue video signal that is 255 gray level.

Subsequently, the amplification portion507converts the second and third video signals before S709into the second and third video signals exhibiting the luminances higher than the luminances exhibited by the second and third video signals before S709(S709and S710). In the above-mentioned specific example, the amplification portion507converts the red video signal of 250 gray level into 261 gray level, and converts the green video signal of 100 gray level into 107 gray level.

Subsequently, the determination portion506determines whether or not the second and third video signals converted by the amplification portion507in S709and S710exceed the second and third predetermined values (S711and S801). Note that, S711and S801are separately described for the sake of convenience in illustrating the flowchart, but the determination portion506simultaneously performs the processing of S711and S801. When neither the second nor third video signal after the conversion performed in S709and S710exceeds the second or third predetermined values, the procedure advances to S712, when both the second and third video signals exceed the predetermined values, the procedure advances to S802, and when one video signal of the second and third video signals exceeds the predetermined value corresponding thereto, the procedure advances to S803.

When the procedure advances to S712, the first to third video signals are output to the source driver204. When the procedure advances to S802, the second and third video signals are converted into the second and third predetermined values, respectively, and output to the source driver204. In the above-mentioned specific example, the red video signal of 260 gray level exceeds the predetermined value of the red video signal of 255, while the green video signal of 107 gray level does not exceed the predetermined value of the green video signal of 255, and hence the determination portion506determines that one video signal of the second and third video signals exceeds the predetermined value corresponding thereto. Therefore, the procedure advances to S803.

Subsequently, when the determination portion506determines in S711and S801that one video signal of the second and third video signals exceeds the predetermined value corresponding thereto, the lapse information retaining portion503deletes the color information corresponding to the video signal determined as exceeding the predetermined value in S711and S801(S803). In the above-mentioned specific example, the red video signal is determined as exceeding the predetermined value of the red video signal, and hence the lapse information retaining portion503deletes the color information indicating red from the color information indicating red and green retained before S803.

Subsequently, the predetermined value conversion portion504converts the video signal determined as exceeding the predetermined value in S711and S801into the predetermined value corresponding thereto (S804). In the above-mentioned specific example, the determination portion506determines in S711and S801that the red video signal exceeds the predetermined value of the red video signal, and hence the predetermined value conversion portion504converts the red video signal of 261 gray level into 255 gray level. Subsequently, the difference calculation portion505calculates the difference from the video signal converted by the predetermined value conversion portion504in S804(S805). In the above-mentioned specific example, the difference calculation portion505calculates the difference of 6 gray level between the red video signal of 261 gray level and 255 gray level.

Subsequently, the amplification portion507converts one of the second and third video signals that is determined in S711and S801as not exceeding the predetermined value based on the information retained by the lapse information retaining portion503and the calculation result obtained in S805by the difference calculation portion505(S806). In the above-mentioned specific example, the lapse information retaining portion503retains the green color information, and hence the amplification portion507converts the green video signal of 107 gray level into 111 gray level.

Subsequently, the determination portion506determines whether or not the second or third video signal converted in S806exceeds the predetermined value corresponding thereto (S807). When it is determined in S807that the second or third video signal exceeds the second or third predetermined value, the predetermined value conversion portion504converts the second or third video signal determined as exceeding the predetermined value into the predetermined value corresponding thereto (S808).

When it is determined in S807that the second or third video signal does not exceed the predetermined value corresponding thereto, the first to third video signals are output to the source driver204(S809). In the above-mentioned specific example, none of the video signals after the conversion exceeds the predetermined value, and hence the video signals of (blue, red, green)=(255, 255, 111) are output to the source driver204.

Note that, the above-mentioned description is directed to the case where the video signals are converted for one pixel having the spacer placed therein, but a video signal conversion portion performs the same video signal conversion as described above for another pixel having the spacer placed therein. On the other hand, the video signals input to the pixel having no spacer placed therein are not selected by the video signal selection portion206, and hence the video signal conversion portion does not perform the same video signal conversion as described above for the video signals input to the pixel having no spacer placed therein. Therefore, in a case where the video signals exhibiting a fixed luminance less than the predetermined value are input to the pixel having the spacer placed therein and the pixel having no spacer placed therein, the source driver204outputs the video signals exhibiting a higher luminance to the pixel having the spacer placed therein than that of the video signals to be output to the pixel having no spacer placed therein.

As described above, the video signal conversion portion207alleviates the reduction in the luminance and display unevenness caused by the spacer301by converting the video signals of the pixel210to which the sub-pixel211having the spacer301therein belongs. The present invention is not limited to the above-mentioned embodiment, and various modifications can be made. For example, the configuration illustrated in the above-mentioned embodiment can be replaced by substantially the same configuration, a configuration producing the same operation effects, or a configuration capable of achieving the same object.

Specifically, for example, the above-mentioned specific example is described above on the assumption that they characteristic is 1, but in actuality, the γ characteristic may be 2.2 or may be another value. However, in a case where the γ characteristic is not 1, the amplification portion507performs the video signal conversion so as to exhibit the same degree of amplification of the luminance as in the case where the γ characteristic is 1.

Further, the above-mentioned description is directed to the case where the blue sub-pixel211has the spacer301placed therein, but the present invention is not limited thereto. For example, the red or green sub-pixel211may have the spacer301placed therein, or as illustrated inFIG. 9, the spacer301may be placed in the red sub-pixel211as well as in the blue sub-pixel211. Alternatively, other combinations may be employed. In a configuration in which a plurality of sub-pixels211among the sub-pixels211that form one pixel210have the spacers301placed therein, the amplification portion507converts the video signals corresponding to the respective sub-pixels211based on a reduction ratio of the area of the light transmission portion caused by the spacers301placed in each of the sub-pixels211.

In addition, the above-mentioned description is directed to the case where one pixel210is formed of the sub-pixels211of the three colors of red, green, and blue. However, the present invention is not limited to the case where one pixel210is formed of the sub-pixels211of the three colors of red, green, and blue, and one pixel210may be formed of the sub-pixels211of four colors such as red, green, blue, and white or red, green, blue, and yellow by adding the sub-pixel211of white or yellow. Further, one pixel210may be formed of the sub-pixels211of five or more colors.

Further, the interference portion described in the claims corresponds to, for example, the above-mentioned spacer301. However, the interference portion is not limited to the spacer, and may be a sensor or the like. Specifically, for example, a photosensor for sensing an intensity of an external light incident to the panel205from an opposite side of the backlight unit103may be placed instead of the spacer301. Note that, the sensor is not limited to the photosensor, and may be another sensor such as a sensor for sensing a change in electrostatic capacity.

Further, although the liquid crystal display device has been described above, the display device may be a display device using various types of light-emitting elements such as organic EL elements, inorganic EL elements, and field-emission devices (FEDs). Further, the display device100described above can be used as various types of display devices for displaying information such as a display for personal computer, a display for TV broadcast reception, or a display for advertisement display. Moreover, the display device100can also be used as a display section of various electronic devices such as a digital still camera, a video camera, a car navigation system, a car audio system, a game machine, and a personal digital assistant.