DISPLAY DEVICE AND COLOR FILTER SUBSTRATE
A display device includes a pixel defined by a plurality of subpixels. The plurality of subpixels include: first and second red subpixels for displaying red; a green subpixel for displaying green; a blue subpixel for displaying blue; and a yellow subpixel for displaying yellow.
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1. Field of the Invention
The present invention relates to a display device, and more particularly to a multiprimary display device which performs display by using four or more primary colors. The present invention also relates to a color filter substrate for use in such a display device.
2. Description of the Related Art
Currently, various display devices are used in a variety of applications. In commonly-used display devices, each pixel is composed of three subpixels for displaying three primaries of light (i.e., red, green and blue), whereby multicolor display is achieved.
A problem of conventional display devices is that they can only display colors in a limited range (referred to as a “color reproduction range” or a “color gamut”).
Therefore, in order to expand the color gamut of a display device, there has been proposed a technique which increases the number of primary colors to be used for displaying to four or more.
For example, as shown in
However, the inventors have performed a detailed study concerning the display quality of multiprimary display devices, and thus found that sufficient display quality cannot be achieved by merely increasing the number of primary colors. For example, in accordance with the display device disclosed in Patent Document 1, the actually-displayed red colors will appear blackish (i.e., dark red), which means that there actually exist some object colors that cannot be displayed.
SUMMARY OF THE INVENTIONIn order to overcome the problems described above, preferred embodiments of the present invention provide: a display device which has an expanded color gamut and is able to display bright red; and a color filter substrate for use in such a display device.
A display device according to a preferred embodiment of the present invention is a display device comprising a pixel defined by a plurality of subpixels, wherein the plurality of subpixels include: first and second red subpixels for displaying red; a green subpixel for displaying green; a blue subpixel for displaying blue; and a yellow subpixel for displaying yellow.
In a preferred embodiment, the first and second red subpixels each have a Y value of no less than 5% and no more than 11%; the green subpixel has a Y value of no less than 20% and no more than 35%; the blue subpixel has a Y value of no less than 5% and no more than 10%; and the yellow subpixel has a Y value of no less than 30% and no more than 50%, where a Y value in the XYZ color system of the pixel when displaying white is defined as 100%.
In a preferred embodiment, the first and second red subpixels each have a dominant wavelength of no less than 605 nm and no more than 635 nm; the green subpixel has a dominant wavelength of no less than 520 nm and no more than 550 nm; the blue subpixel has a dominant wavelength of no more than 470 nm; and the yellow subpixel has a dominant wavelength of no less than 565 nm and no more than 580 nm.
In a preferred embodiment, the first and second red subpixels each have a color purity of no less than 90%; the green subpixel has a color purity of no less than 65% and no more than 80%; the blue subpixel has a color purity of no less than 90% and no more than 95%; and the yellow subpixel has a color purity of no less than 85% and no more than 95%.
In a preferred embodiment, the plurality of subpixels are of substantially the same size.
In a preferred embodiment, the first and second red subpixels are driven independently of each other.
In a preferred embodiment, the first and second red subpixels are driven by a same switching element.
In a preferred embodiment, within the pixel, the first red subpixel and the second red subpixel are disposed contiguous to each other.
In a preferred embodiment, within the pixel, the green subpixel and the yellow subpixel are disposed contiguous to each other and interposed between other subpixels.
In a preferred embodiment, within the pixel, the first red subpixel, the second red subpixel, the green subpixel, and the yellow subpixel are disposed contiguous to one another.
In a preferred embodiment, plurality of subpixels further include a cyan subpixel for displaying cyan.
In a preferred embodiment, the cyan subpixel has a Y value of no less than 10% and no more than 30%, where a Y value in the XYZ color system of the pixel when displaying white is defined as 100%.
In a preferred embodiment, the cyan subpixel has a dominant wavelength of no less than 475 nm and no more than 500 nm.
In a preferred embodiment, the cyan subpixel has a color purity of no less than 65% and no more than 80%.
In a preferred embodiment, within the pixel, the cyan subpixel, the green subpixel, and the blue subpixel are disposed contiguous to one another.
In a preferred embodiment, a display device according to the present invention is a liquid crystal display device comprising a liquid crystal layer.
A color filter substrate according to a preferred embodiment of the present invention is a color filter substrate for a display device having a pixel defined by a plurality of subpixels, comprising: a substrate; and a plurality of color filters provided in a region of the substrate corresponding to the pixel, wherein, the plurality of color filters include: first and second red color filters for allowing red light to be transmitted therethrough; a green color filter for allowing green light to be transmitted therethrough; a blue color filter for allowing blue light to be transmitted therethrough; and a yellow color filter for allowing yellow light to be transmitted therethrough.
In a preferred embodiment, the plurality of color filters further include a cyan color filter for allowing cyan light to be transmitted therethrough.
A pixel of a display device according to a preferred embodiment of the present invention includes not only subpixels for displaying red, green and blue, but also subpixels for displaying other colors. In other words, more than three primary colors are used for displaying by the display device according to a preferred embodiment of the present invention, thus resulting in a color gamut which is wider than that of a conventional display device which uses three primaries for displaying. Moreover, the pixel of the display device according to a preferred embodiment of the present invention includes two subpixels for displaying red, whereby the Y value of red can be improved and bright red can be displayed.
Other features, elements, processes, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments of the present invention with reference to the attached drawings.
Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.
Before describing embodiments of the present invention, the reason why red appears blackish (dark) in the liquid crystal display device 800 disclosed in Patent Document 1 will be described.
When the number of primary colors to be used for displaying is increased, the number of subpixels per pixel increases, which inevitably reduces the area of each subpixel. This results in a lowered lightness (which corresponds to the Y value in the XYZ color system) of the color to be displayed by each subpixel. For example, if the number of primary colors used for displaying is increased from three to six, the area of each subpixel is reduced to about half, so that the lightness (Y value) of each subpixel is also reduced to about half.
“Lightness” is one of the three factors which define a color, the other two being “hue” and “chroma”. Therefore, even if the color gamut on the xy chromaticity diagram (i.e., reproducible range of “hue” and “chroma”) may be broadened by increasing the number of primary colors as shown in
According to a study by the inventors, while subpixels for displaying green and blue can still sufficiently display various object colors under lowered lightness, it is the subpixels for displaying red that become unable to display some object colors under lowered lightness. If the lightness (Y value) becomes lower because of using an increased number of primary colors, the display quality of red is degraded such that red appears blackish red (i.e., dark red).
The present invention has been made based on the above findings. Hereinafter, embodiments of the present invention will be described with reference to the figures. Although the following descriptions will be directed to liquid crystal display devices as an example, the present invention can be suitably used for various display devices such as CRTs (cathode-ray tubes), organic EL display devices, plasma display panels, and SEDs (Surface-conduction Electron-emitter Displays), as well as liquid crystal display devices.
As shown in
The liquid crystal display device 100 according to the present preferred embodiment has a wide color gamut because it uses more primary colors for displaying than any commonly-used liquid crystal display device that uses three primaries to perform display.
Note that the color gamut shown in
Moreover, since each pixel of the liquid crystal display device 100 according to the present preferred embodiment includes two subpixels for displaying red (i.e., first and second subpixels R1 and R2), the lightness (Y value) of red can be improved over that of the liquid crystal display device 800 shown in
Now, improvement in the Y value of the liquid crystal display device 100 will be specifically described, in comparison with the multiprimary liquid crystal display device 800 of Patent Document 1.
Table 1 exemplifies a Y value, xy chromaticity, dominant wavelength (or complementary wavelength for magenta), and color purity of each subpixel, as well as its display quality, in the multiprimary liquid crystal display device 800 of Patent Document 1. Table 1 also shows a Y value, xy chromaticity, and color temperature of the case where the pixel is displaying white. The Y value of each subpixel represents a relative value taken against the Y value of the pixel when displaying white (defined as 100%). The dominant wavelength and complementary wavelength roughly represent hue. The color purity roughly represents chroma. Moreover,
As shown in Table 1, the subpixels R, B and Ye for displaying red, blue and yellow have a poor display quality. Moreover, the subpixel C for displaying cyan has a slightly inferior display quality to those of the subpixels G and M for displaying green and magenta. Note however that the results shown in Table 1 do not immediately apply to the primary colors that are used for displaying. The reason is that yellow, cyan and magenta can always be displayed through additive mixing of red, green and blue. Therefore, each of these colors (cyan, yellow, magenta) must be evaluated with respect to both of: the color which is displayed by the subpixel Ye, C or M alone; and a color which is displayed through additive color mixing.
Specifically, yellow must be evaluated with respect to both of: a yellow color which is displayed through mixing of the red which is displayed by the red subpixel R and the green which is displayed by the green subpixel G; and a yellow color which is displayed by the yellow subpixel Ye alone. Cyan must be evaluated with respect to both of: a cyan color which is displayed through mixing of the green which is displayed by the green subpixel G and the blue which is displayed by the blue subpixel B; and a cyan color which is displayed by the cyan subpixel C alone. Magenta must be evaluated with respect to both of: a magenta color which is displayed through mixing of the red which is displayed by the red subpixel R and the blue which is displayed by the blue subpixel B; and a magenta color which is displayed by the magenta subpixel M alone.
Table 2 exemplifies a Y value, xy chromaticity, dominant wavelength (or complementary wavelength for magenta), and color purity of each of the primary colors used for displaying by the liquid crystal display device 800, as well as its display quality.
It can be seen from Table 2 that a sufficient display quality is obtained also for yellow and cyan. This is a result of a greatly improved Y value, which in turn is obtained by taking into account (almost via a simple arithmetic sum) the color which is created through additive color mixing of other subpixels.
However, as shown in Table 2, the display quality for red is still low. This is because the Y value has become lower due to the increased number of primary colors. Incidentally, it appears that the display quality for blue is also low in the illustrated example. However, this is ascribable to an excessively low Y value which is associated with the specifications of the color filters and backlight that were used in this particular example. The low Y value for blue is not an essential problem because it can be overcome by changing the specifications of the color filters and backlight.
Next, Table 3 exemplifies a Y value, xy chromaticity, dominant wavelength, and color purity of each subpixel, as well as its display quality, in the liquid crystal display device 100 according to the present preferred embodiment. Moreover,
As seen from Table 3, when looking at each subpixel alone, it appears that the first red subpixel R1, the second red subpixel R2, and the yellow subpixel Ye have a poor display quality. The display quality of the cyan subpixel C is also slightly inferior to those of the green subpixel G and the blue subpixel B. However, also in the liquid crystal display device 100 according to the present preferred embodiment, the results shown in Table 3 do not immediately apply to the primary colors that are used for displaying. In other words, each display quality rating shown in Table 3 merely represents a “display quality of a subpixel”, rather than a “display quality of a primary color” that is used for displaying.
As has already been described, yellow and cyan must be evaluated with respect to both of: a color which is displayed by the yellow subpixel Ye or the cyan subpixel C alone; and a color which is displayed through additive color mixing. Red must be evaluated with respect to both of the red which is displayed by the first red subpixel R1 and the red which is displayed by the second red subpixel R2. In the liquid crystal display device 100 according to the present preferred embodiment, too, magenta can be displayed through color mixing (i.e., mixing of the red colors displayed by the first and second red subpixels R1 and R2 and the blue displayed by the blue subpixel B).
Table 4 exemplifies a Y value, xy chromaticity, dominant wavelength (or complementary wavelength for magenta), and color purity of each of the primary colors used for displaying by the liquid crystal display device 100 according to the present preferred embodiment, as well as its display quality.
As can be seen from Table 4, a very good display quality is obtained for yellow and cyan, and also for magenta. Furthermore, red also has a greatly improved Y value, thus resulting in a substantially improved display quality.
Now, the difference in red reproduction range between the liquid crystal display device 100 according to the present preferred embodiment and the liquid crystal display device 800 of Patent Document 1 will be described more specifically.
As can be seen from
Note that the liquid crystal display device 100 according to the present preferred embodiment lacks any subpixels for displaying magenta, whereas the liquid crystal display device 800 of Patent Document 1 includes subpixels for displaying magenta. The inventors have also studied the impact of this omission on the displaying of magenta.
As can be seen from
The reason why magenta object colors can be sufficiently reproduced even if magenta subpixels are omitted is that, as shown in
As described above, a liquid crystal display device according to the present preferred embodiment has a wide color gamut, and is able to display bright red. Note that the red which is displayed by the first red subpixel R1 and the red which is displayed by the second red subpixel R1 may be identical or different. In the case where they are identical, the manufacturing process of color filters can be shortened. In the case where they are different, there are six primary colors to be displayed by the subpixels (i.e., the color gamut has a hexagonal shape on the chromaticity diagram), and therefore the number of reproducible colors (in particular the number of displayed colors in the vicinity of red) increases.
Next, preferable ranges for the Y value, dominant wavelength, and color purity of each subpixel of the liquid crystal display device 100 will be discussed.
In order to achieve highly true color reproduction, it is preferable to determine the lightness (i.e., Y value) of each primary color used for displaying in accordance with the lightness of object colors.
In order to reproduce colors of high chroma, as shown in
Similarly, in order to reproduce colors of high chroma, as shown in
When the Y value is too low, a blackish color will result even if the chroma may be high. For example, red will appear as scarlet, yellow as ocher, and green or blue as black. Conversely, if the Y value is too high, the display will resemble luminous colors, which would be odd. This tendency is especially true of red and green. As for cyan, a good display quality can be obtained in a relatively broad range of Y values, as can be seen from
Table 5 shows preferable ranges for the Y value, dominant wavelength, and color purity of each primary color used for displaying by the liquid crystal display device 100.
As has already been described, it is preferable that: red has a Y value of no less than 10% and no more than 22%; green has a Y value of no less than 20% and no more than 35%; blue has a Y value of no less than 5% and no more than 10%; yellow has a Y value of no less than 60% and no more than 85%; cyan has a Y value of no less than 10% and no more than 55%; and magenta has a Y value of no less than 15% and no more than 30%.
Moreover, it is preferable that: red has a dominant wavelength of no less than 605 nm and no more than 635 nm; green has a dominant wavelength of no less than 520 nm and no more than 550 nm; blue has a dominant wavelength of no more than 470 nm; yellow has a dominant wavelength of no less than 565 nm and no more than 580 nm; and cyan has a dominant wavelength of no less than 475 nm and no more than 500 nm.
Furthermore, it is preferable that: red has a color purity of no less than 90%; green has a color purity of no less than 65% and no more than 80%; blue has a color purity of no less than 90% and no more than 95%; yellow has a color purity of no less than 85% and no more than 95%; cyan has a color purity of no less than 65% and no more than 80%; and magenta has a color purity of no less than 60% and no more than 80%.
As for red, the first and second red subpixels R1 and R2 contribute to display. As for yellow, the first and second red subpixels R1 and R2, the yellow subpixel Ye, and the green subpixel G contribute to display. As for cyan, the green subpixel G, the cyan subpixel C, and the blue subpixel B contribute to display. As for magenta, the first and second red subpixels R1 and R2 and the blue subpixel B contribute to display. When these facts are taken into consideration, the preferable ranges for the dominant wavelength, Y value, and color purity of each subpixel of the liquid crystal display device 100 are as shown in Table 6.
As shown in Table 6, it is preferable that: the first and second red subpixels R1 and R2 each have a Y value of no less than 5% and no more than 11%; the green subpixel G has a Y value of no less than 20% and no more than 35%; the blue subpixel B has a Y value of no less than 5% and no more than 10%; the yellow subpixel Ye has a Y value of no less than 30% and no more than 50%; and the cyan subpixel C has a Y value of no less than 10% and no more than 30%.
Moreover, it is preferable that: the first and second red subpixels R1 and R2 each have a dominant wavelength of no less than 605 nm and no more than 635 nm; the green subpixel G has a dominant wavelength of no less than 520 nm and no more than 550 nm; the blue subpixel B has a dominant wavelength of no more than 470 nm; the yellow subpixel Ye has a dominant wavelength of no less than 565 nm and no more than 580 nm; and the cyan subpixel C has a dominant wavelength of no less than 475 nm and no more than 500 nm.
Furthermore, it is preferable that: the first and second red subpixels R1 and R2 each have a color purity of no less than 90%; the green subpixel G has a color purity of no less than 65% and no more than 80%; the blue subpixel B has a color purity of no less than 90% and no more than 95%; the yellow subpixel Ye has a color purity of no less than 85% and no more than 95%; and the cyan subpixel C has a color purity of no less than 65% and no more than 80%.
By prescribing the Y value, dominant wavelength, and color purity of each subpixel so as to be within the aforementioned preferable ranges, it becomes possible to enhance the effects of the present invention of expanding the color gamut and enabling displaying of bright red.
The inventors have produced a number of prototypes of the liquid crystal display device 100 according to the present preferred embodiment, with varying color filter and backlight specifications. These prototypes exhibited display qualities as follows. The display quality results will be shown in Tables 7 to 20 below. It must be noted that each display quality rating recited in any of Tables 7, 9, 11, 13, 15, 17 and 19 is a “display quality of a subpixel”, whereas each display quality rating recited in any of Tables 8, 10, 12, 14, 16, 18 and 20 is a “display quality of a primary color”.
Example 1Table 7 shows the Y value, xy chromaticity, dominant wavelength, color purity, and display quality of each subpixel in this Example. Table 8 shows the Y value, xy chromaticity, dominant wavelength (or complementary wavelength for magenta), color purity, and display quality of each primary color in this Example. Moreover, spectral transmittance characteristics of color filters and a backlight spectrum in this Example are shown in
As seen from Table 7, the Y value, dominant wavelength, and color purity of each subpixel are generally within the preferable value ranges as shown in Table 6. Therefore, as seen from Table 8, the Y value, dominant wavelength, and color purity of each primary color are generally within the preferable value ranges as shown in Table 5. As a result, a very good display quality was obtained with respect to all primary colors.
Table 9 shows the Y value and other parameters of each subpixel in this Example, and Table 10 shows the Y value and other parameters of each primary color in this Example. Moreover, spectral transmittance characteristics of color filters and a backlight spectrum in this Example are shown in
As seen from Table 9, the Y value, dominant wavelength, and color purity of each subpixel are generally within the preferable value ranges as shown in Table 6. Therefore, as seen from Table 10, the Y value, dominant wavelength, and color purity of each primary color are generally within the preferable value ranges as shown in Table 5. As a result, a very good display quality was obtained with respect to red, green, yellow, and cyan; and a good display quality was obtained with respect to blue and magenta.
Table 11 shows the Y value and other parameters of each subpixel in this Example, and Table 12 shows the Y value and other parameters of each primary color in this Example. Moreover, spectral transmittance characteristics of color filters and a backlight spectrum in this Example are shown in
As seen from Table 11, the Y value, dominant wavelength, and color purity of each subpixel are generally within the preferable value ranges as shown in Table 6. Therefore, as seen from Table 12, the Y value, dominant wavelength, and color purity of each primary color are generally within the preferable value ranges as shown in Table 5. As a result, a very good display quality was obtained with respect to red, yellow, cyan, and magenta; and a good display quality was obtained with respect to green and blue.
Table 13 shows the Y value and other parameters of each subpixel in this Example, and Table 14 shows the Y value and other parameters of each primary color in this Example. Moreover, spectral transmittance characteristics of color filters and a backlight spectrum in this Example are shown in
As seen from Table 13, the Y value, dominant wavelength, and color purity of each subpixel are generally within the preferable value ranges as shown in Table 6. Therefore, as seen from Table 14, the Y value, dominant wavelength, and color purity of each primary color are generally within the preferable value ranges as shown in Table 5. As a result, a very good display quality was obtained with respect to red, green, yellow, cyan, and magenta; and a good display quality was obtained with respect to blue.
Table 15 shows the Y value and other parameters of each subpixel in this Example, and Table 16 shows the Y value and other parameters of each primary color in this Example. Moreover, spectral transmittance characteristics of color filters and a backlight spectrum in this Example are shown in
As seen from Table 15, the Y value, dominant wavelength, and color purity of each subpixel are generally within the preferable value ranges as shown in Table 6. Therefore, as seen from Table 16, the Y value, dominant wavelength, and color purity of each primary color are generally within the preferable value ranges as shown in Table 5. As a result, a very good display quality was obtained with respect to red, blue, yellow, cyan, and magenta; and a good display quality was obtained with respect to green.
Table 17 shows the Y value and other parameters of each subpixel in this Example, and Table 18 shows the Y value and other parameters of each primary color in this Example. Moreover, spectral transmittance characteristics of color filters and a backlight spectrum in this Example are shown in
As seen from Table 17, the Y value, dominant wavelength, and color purity of each subpixel are generally within the preferable value ranges as shown in Table 6. Therefore, as seen from Table 18, the Y value, dominant wavelength, and color purity of each primary color are generally within the preferable value ranges as shown in Table 5. As a result, a very good display quality was obtained with respect to red, green, yellow, and magenta; and a good display quality was obtained with respect to blue and cyan.
Table 19 shows the Y value and other parameters of each subpixel in this Example, and Table 20 shows the Y value and other parameters of each primary color in this Example. Moreover, spectral transmittance characteristics of color filters and a backlight spectrum in this Example are shown in
As seen from Table 19, the Y value, dominant wavelength, and color purity of each subpixel are generally within the preferable value ranges as shown in Table 6. Therefore, as seen from Table 20, the Y value, dominant wavelength, and color purity of each primary color are generally within the preferable value ranges as shown in Table 5. As a result, a very good display quality was obtained with respect to green, yellow, blue, cyan and magenta; and a good display quality was obtained with respect to red.
Table 21 shows the Y value and other parameters of each subpixel in this Example, and Table 22 shows the Y value and other parameters of each primary color in this Example. Moreover, spectral transmittance characteristics of color filters and a backlight spectrum in this Example are shown in
As seen from Table 21, since the first and second red subpixels R1 and R2 had a slightly low Y value of 4%, which is not within the preferable value range shown in Table 6 (i.e., no less than 5% and no more than 11%), the Y value of red was not sufficiently raised. As a result, as seen from Table 22, the Y value of red was slightly low, i.e., 7.9%, which is not within the preferable value range shown in Table 5 (i.e., no less than 10% and no more than 22%). This makes the displayed red slightly darker than is attained in Examples 1 to 7. Moreover, since the first and second red subpixels R1 and R2 had a slightly low Y value, the Y value of magenta was not sufficiently raised. As a result, as seen from Table 22, the Y value of magenta was slightly low, i.e., 13.1%, which is not within the preferable value range (i.e., no less than 15% and no more than 30%) shown in Table 5. This makes the displayed magenta slightly darker than is attained in Examples 1 to 7.
Next, preferable examples of subpixel arrangement within a pixel will be described.
First,
It is preferable that, as shown in
Next,
It is preferable that, as shown in
Next,
It is preferable that, as shown in
Next,
It is preferable that, as shown in
Next,
The present preferred embodiment has been described with respect to the case where a plurality of subpixels are arranged in a single row within each pixel, as exemplified in FIG. 1. Alternatively, the present invention is also applicable to a liquid crystal display device 200 shown in
Now, preferable subpixel arrangements in the case where mosaic arrangement is adopted will be described.
First,
By disposing the first red subpixel R1 and second red subpixel R2 so as to be contiguous within the pixel as shown in
Next,
As shown in
Next,
It is preferable that, as shown in
Next,
It is preferable that, as shown in
Next,
Alternatively, it is also preferable that, as shown in
Although the above description has been directed to constructions where each pixel is defined by six subpixels, the present invention is not limited thereto. Also in constructions where each pixel is defined by more (seven or more) subpixels, or each pixel is defined by five subpixels, the effect of displaying bright red can be obtained so long as each pixel includes the first red subpixel R1 and second red subpixel R2.
Also when a construction as shown in
In the case where each pixel is defined by five subpixels, too, it is preferable that the first red subpixel R1 and second red subpixel R2 are contiguous, and that the green subpixel G and yellow subpixel Ye are contiguous and interposed between other subpixels, as exemplified in
In the case where each pixel is defined by five subpixels, it is preferable that each pixel includes the yellow subpixel Ye, rather than the cyan subpixel C. Since the yellow subpixel Ye has a higher Y value than does the cyan subpixel C, inclusion of the yellow subpixel Ye will allow for brighter display across the entire pixel.
In the constructions illustrated above, the plurality of subpixels defining each pixel are of substantially the same size. Alternatively, the plurality of subpixels defining each pixel may be of different sizes, as exemplified in
However, using subpixels of different sizes may make the designing of the display device difficult, or complicate the production steps of the display device. Such problems will not occur in the case where the plurality of subpixels defining each pixel are of substantially same size.
Next, the more specific structure of the liquid crystal display devices 100 and 200 according to the present embodiment will be described.
As shown in
Although not shown, a plurality of switching elements (e.g., TFTs) and pixel electrodes which are electrically connected to the respective switching elements are provided on the active matrix substrate 10.
Typically, as shown in
When using a construction where the first red subpixel R1 and second red subpixel R2 are driven independently of each other, it is possible to reduce the viewing angle dependence of γ characteristics (i.e., disagreement between the γ characteristics when observing a display surface in the frontal direction and the γ characteristics when observing the display surface in an oblique direction).
As a technique for reducing the viewing angle dependence of γ characteristics, a technique called multipixel driving is proposed in Japanese Laid-Open Patent Publication Nos. 2004-62146 and 2004-78157. In this technique, one subpixel is divided into two regions, and different voltages are applied to these regions, whereby the viewing angle dependence of γ characteristics is reduced.
When using a construction where the first red subpixel R1 and second red subpixel R2 are driven independently of each other, it is naturally possible to apply different voltages across the liquid crystal layer over the first red subpixel R1 and the liquid crystal layer over the second red subpixel R2. Therefore, an effect of reducing the viewing angle dependence of γ characteristics is obtained, similarly to the multipixel driving disclosed in Japanese Laid-Open Patent Publication Nos. 2004-62146 and 2004-78157, supra.
With respect to the liquid crystal display device 100, for example, a specific construction of the color filter substrate 20 is shown in
Specifically, the plurality of color filters are: first and second red color filters 22R1 and 22R2 which allow red light to be transmitted therethrough; a green color filter 22G which allows green light to be transmitted therethrough; a blue color filter 22B which allows blue light to be transmitted therethrough; a yellow color filter 22Ye which allows yellow light to be transmitted therethrough; and a cyan color filter 22C which allows cyan light to be transmitted therethrough.
A black matrix 23 is provided in between color filters. Moreover, a counter electrode 24 is provided on the color filters and the black matrix 23.
The color filters can be formed by a known technique, e.g., ink jet technique.
As has already been described, the liquid crystal display devices 100 and 200 perform multiprimary display. Therefore, the liquid crystal display devices 100 and 200 include a multiprimary controller which receives externally-input image signals and generates various control signals for multiprimary displaying. An example of a multiprimary controller is shown in
The multiprimary controller 40 shown in
Externally-input RGB signals are converted by the conversion matrix 41 into signals (XYZ signals) which correspond to the color space of the XYZ color system. The XYZ signals are mapped by the mapping unit 42 onto the xy coordinate space, whereby signals corresponding to the Y value and chromaticity coordinates (x, y) are generated. There are as many two-dimensional look-up tables 43 as there are primary colors. Based on these two-dimensional look-up tables 43, data (r, g, b, ye, c) corresponding to the hue and chroma of the color to be displayed in each subpixel is generated from the chromaticity coordinates (x, y). Such data and the Y value are multiplied in the multiplier 44, whereby signals R, G, B, Ye, and C corresponding to the respective primary colors are generated. Note that the technique for generating signals for multiprimary displaying is not to be limited to the technique described herein, which is only exemplary.
According to the present invention, there is provided a display device which has a wide color gamut and is able to display bright red. Also according to the present invention, there is provided a color filter substrate to be used in such a display device.
The present invention is suitably used for various display devices, e.g., liquid crystal display devices, CRTs (cathode-ray tubes), organic EL display devices, plasma display panels, and SEDs (Surface-conduction Electron-emitter Displays).
While the present invention has been described with respect to preferred embodiments thereof, it will be apparent to those skilled in the art that the disclosed invention may be modified in numerous ways and may assume many embodiments other than those specifically described above. Accordingly, it is intended by the appended claims to cover all modifications of the invention that fall within the true spirit and scope of the invention.
This non-provisional application claims priority under 35 USC §119(a) on Patent Application No. 2005-274510 filed in Japan on Sep. 21, 2005, the entire contents of which are hereby incorporated by reference.
Claims
1. A display device comprising a pixel defined by a plurality of subpixels, wherein the plurality of subpixels include: at least one red subpixel arranged to display red; a green subpixel arranged to display green; and a blue subpixel arranged to display blue, the at least one red subpixel being larger than each of the green subpixel and the blue subpixel.
2. The display device of claim 1, wherein the at least one red subpixel includes a first red subpixel and a second red subpixel.
3. The display device of claim 1, further comprising a yellow subpixel arranged to display yellow.
4. The display device of claim 3, wherein the yellow subpixel is larger than the blue subpixel.
5. The display device of claim 3, wherein the at least one red subpixel is larger than the yellow subpixel.
6. The display device of claim 3, wherein the at least one red subpixel includes a first red subpixel and a second red subpixel, wherein the yellow subpixel is larger than each of the first and second red subpixels.
7. The display device of claim 2, wherein the green subpixel is larger than each of the first and second red subpixels.
8. The display device of claim 1, wherein the green subpixel is larger than the blue subpixel.
9. The display device of claim 1, further comprising a cyan subpixel arranged to display cyan.
10. The display device of claim 9, wherein the at least one red subpixel is larger than the cyan subpixel.
11. The display device of claim 1, further comprising a yellow subpixel arranged to display yellow and a cyan subpixel arranged to display cyan, wherein the at least one red subpixel is larger than each of the yellow subpixel and the cyan subpixel.
12. The display device of claim 1, further comprising a yellow subpixel arranged to display yellow and a cyan subpixel arranged to display cyan, wherein the at least one red subpixel includes a first red subpixel and a second red subpixel, and the first red subpixel, the second red subpixel, the blue subpixel, the green subpixel, the yellow subpixel and the cyan subpixel are substantially the same size.
13. The display device of claim 2, wherein each of the first red subpixel, the second red subpixel, the blue subpixel and the green subpixel are substantially the same size.
14. The display device of claim 2, wherein the red displayed by the first red subpixel is different from the red displayed by the second red subpixel.
15. The display device of claim 2, wherein the red displayed by the first red subpixel is the same as the red displayed by the second red subpixel.
16. The display device of claim 1, wherein, the at least one red subpixel has a Y value of no less than 5% and no more than 11%; the green subpixel has a Y value of no less than 20% and no more than 35%; and the blue subpixel has a Y value of no less than 5% and no more than 10%, where a Y value in the XYZ color system of the pixel when displaying white is defined as 100%.
17. The display device of claim 1, wherein, the at least one red subpixel has a dominant wavelength of no less than 605 nm and no more than 635 nm; the green subpixel has a dominant wavelength of no less than 520 nm and no more than 550 nm; and the blue subpixel has a dominant wavelength of no more than 470 nm.
18. The display device of claim 1, wherein, the at least one red subpixel has a color purity of no less than 90%; the green subpixel has a color purity of no less than 65% and no more than 80%; and the blue subpixel has a color purity of no less than 90% and no more than 95%.
19. The display device of claim 2, wherein the first and second red subpixels are driven independently of each other.
20. The display device of claim 2, wherein the first and second red subpixels are driven by a same switching element.
21. The display device of claim 2, wherein, within the pixel, the first red subpixel and the second red subpixel are disposed contiguous to each other.
22. The display device of claim 3, wherein, within the pixel, the green subpixel and the yellow subpixel are disposed contiguous to each other and interposed between other subpixels.
23. The display device of claim 3, wherein, the at least one red subpixel includes a first red subpixel and a second red subpixel, and within the pixel, the first red subpixel, the second red subpixel, the green subpixel, and the yellow subpixel are disposed contiguous to one another.
24. The display device of claim 1, wherein the display device is one of a liquid crystal display device comprising a liquid crystal layer, an organic EL display device, a cathode-ray tube display device, a plasma display panel, and a surface-conduction electron-emitter display device.
25. The display device of claim 1, wherein, within the pixel, the green subpixel is interposed between others of the subpixels.
26. The display device of claim 9, wherein, within the pixel, the cyan subpixel is interposed between others of the subpixels.
27. The display device of claim 9, wherein, within the pixel, the green subpixel and the cyan subpixel are disposed contiguous to each other and interposed between others of the subpixels.
28. The display device of claim 1, wherein, within the pixel, the blue subpixel is interposed between others of the subpixels.
29. The display device of claim 3, wherein, within the pixel, the blue subpixel and the yellow subpixel interpose at least one of the other subpixels between them.
Type: Application
Filed: Jun 3, 2010
Publication Date: Sep 23, 2010
Applicant: SHARP KABUSHIKI KAISHA (Osaka)
Inventors: Kozo NAKAMURA (Kashiba-shi), Kazunari TOMIZAWA (Soraku-gun)
Application Number: 12/792,909