JP2008233803A - Display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve visual resolution of a display device. <P>SOLUTION: The display device has a plurality of display pixels arrayed in matrix, and respective unit pixels 10 which are sampled at the same time by colors for color display comprise four display pixels 12R, 12G, 12B, and 12W of red, green, blue, and white. In one unit pixel 10, four display pixels are arranged in one array and the green display pixel 12G and white display pixel 12W are arranged adjacently in the center of the one unit pixel 10 to reduce mutual influence of adjacent unit pixels 10 and also improve the visual resolution. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention has a display panel in which a plurality of signal lines and a plurality of scanning lines are arranged in a matrix and display pixels are arranged in the vicinity of each intersection, and one unit pixel for performing color display is made red, green The present invention relates to a display device composed of four display pixels arranged adjacent to each other in a row in the display panel assigned to four colors, blue and white.

  There is known a color liquid crystal display device that performs color display by dividing one unit pixel for performing color display into three display pixels of red, green, and blue.

  In such a color liquid crystal display device in which one unit pixel is divided into three display pixels of red, green, and blue, if it is attempted to increase the color purity when displaying a single color of red, green, or blue, transmission is performed. A low-rate color filter had to be used, and the overall transmittance was lower than that of a color liquid crystal display device with low color purity.

  Therefore, in Patent Document 1, a liquid crystal composition is sandwiched between a pair of substrates, a color filter having a different hue for color display is provided on one of the pair of substrates, and a switching element for pixel selection is provided on the other. In the liquid crystal display device, a display pixel constituting one unit pixel for performing the color display is composed of four display pixels, and the display pixels are arranged in a region of three display pixels on the other substrate among the four display pixels. By arranging color filters corresponding to the three primary colors (red, green, and blue) on the corresponding one of the substrates and arranging a color filter corresponding to white in an area corresponding to the other one display pixel, a liquid crystal display It has been proposed to improve the brightness of the device.

Further, in Patent Document 1, the color balance is obtained by setting the gradation value input to the white display pixel to the smallest value among the three gradation values input to the display pixels corresponding to the three primary colors. It is also disclosed that the luminance can be improved while preventing the deviation.
JP 11-295717 A

  However, if the arrangement of the display pixels in the unit pixel is in the order of red, green, blue, and white as disclosed in the above-mentioned Patent Document 1, when the gradation value input to the white display pixel is relatively large, the unit The luminance distribution in the pixel is biased toward the portion where the white display pixel exists.

  An example will be described with reference to FIGS. 10 (A) and 10 (B). Here, FIG. 10A is a diagram illustrating a positional relationship between unit pixels, and FIG. 10B is a diagram illustrating an example of input image data.

  A display with gradation values (Dr, Dg, Db) = (255, 255, 255) of (red, green, blue) and a display with (Dr, Dg, Db) = (0, 0, 0) The unit pixel C which is displayed on the unit pixel A and the unit pixel B adjacent to the left and right, and the unit pixel C adjacent to the left side of the unit pixel A has the same gradation value (Dr, Dg, Db) = (255, 255). 255), the unit pixel D adjacent to the right side of the unit pixel B is displayed with the same gradation value (Dr, Dg, Db) = (0, 0, 0) as the unit pixel B (here, It will be described as a liquid crystal display device with 256 gradations).

At this time, if the lighting environment is uniform and there is no influence of outside light, the luminance is proportional to the transmittance, but the arrangement of the display pixels in each unit pixel is red, green, blue, white in order from the left. In some cases, the transmittance for each display pixel in the two unit pixels A and B is 4.7%, 13.2%, 3.5%, 18.0%, 0.0%, 0.0 in this order. %, 0.0%, and 0.0%. (This transmittance is determined by the characteristics of the color filter.)
When an observer observes this image, smoothing is performed according to the characteristics of human eyes.

  The smoothing relational expression varies depending on the viewing distance, visual acuity, etc., but the product of the product of the coefficient determined by the distance between the target position and the surrounding display pixels that affect the position and the luminance of the display pixel. Can be approximated by the sum.

Here, as an example of an approximate expression, an expression derived from a normal distribution,
T ′ = 0.003 × T (−4) + 0.024 × T (−3) + 0.097 × T (−2) + 0.226 × T (−1) + 0.300 × T (0) +0.226 × T (1) + 0.097 × T (2) + 0.024 × T (3) + 0.003 × T (4)
Is used.

However,
T ′: transmittance after smoothing of target position (luminous transmittance)
T (i): The transmittance before smoothing of a display pixel whose distance from the target position is i display pixels (a positive value on the right side and a negative value on the left side).

  In this case, the distribution of luminous transmittance in the two unit pixels A and B is 9.9%, 9.4%, 9.0%, 7.6%, 4.7%, 1.9%. , 0.4%, 0.1%, and as shown in FIG. 11, the influence of the white display pixel having a high transmittance of the unit pixel A reaches the region in the unit pixel B where black should be originally displayed. I'll be stuck. 11 shows the display pixel transmittance (the product of the transmittance of the display pixel and the gradation value (the product itself of 1 for the unit pixel A and 0 for the unit pixel B)) and the smoothed transmittance distribution in terms of visual perception. R, G, B, and W indicated on the horizontal axis indicate a red display pixel, a green display pixel, a blue display pixel, and a white display pixel.

  Thus, a more faithful display cannot be obtained especially at the boundary where the luminance changes greatly, and the visual resolution is lowered.

  Further, as disclosed in Patent Document 1, when the arrangement of display pixels in a unit pixel is in the order of red, green, blue, and white, the luminance space in a skin color to yellow color that is sensitive to human vision. There is a phenomenon in which the visual resolution is deteriorated as the frequency is lowered.

  For example, when displaying uniform yellow, (Dr, Dg, Db) = (255, 255, 0) as a gradation value of (red, green, blue) (256 gradation liquid crystal display) In the case of display on a liquid crystal display device having a display pixel arrangement of red, green, blue, and white, the gradation values (D′ r, D) input to the display pixels of red, green, blue, and white 'g, D'b, D'w) = (255, 255, 0, 0), and the distribution of the display pixel transmittance within the unit pixel is 4.7%, 13.2 as shown in FIG. %, 0.0%, and 0.0%.

  The spatial frequency of luminance is the reciprocal of the width of one unit pixel.

  Depending on the pixel density, when such a low spatial frequency display is performed, especially when displaying a skin color to yellow color sensitive to the human eye, each display pixel is not sufficiently mixed, and yellow and black (or (Dark gray or dark blue) is recognized as being displayed alternately.

  As described above, the visual resolution is lowered even in a skin color to a yellowish color that is sensitive to human vision.

  The present invention has been made in view of the above points, and an object thereof is to provide a display device capable of improving the visual resolution.

The display device according to claim 1 comprises:
A display device in which a plurality of display pixels are arranged in a matrix and each unit pixel for performing color display is composed of four display pixels of red, green, blue, and white,
Within one unit pixel, the four display pixels are arranged in a line,
A green display pixel and a white display pixel are arranged adjacent to each other in the center of the one unit pixel.

The display device according to claim 2 is the display device according to claim 1,
Each of the display pixels of red, green, and blue in each unit pixel is displayed based on a display signal sampled simultaneously.

The display device according to claim 3 is the display device according to claim 1 or 2,
The red display pixel and the green display pixel are arranged separately in one unit pixel and between adjacent unit pixels.

The display device according to claim 4 comprises:
A display device in which a plurality of display pixels are arranged in a matrix and each unit pixel for performing color display is composed of four display pixels of red, green, blue, and white,
In one unit pixel, the four display pixels are arranged in a line,
The red display pixel and the green display pixel are arranged separately in one unit pixel and between adjacent unit pixels.

The display device according to claim 5 is the display device according to claim 4,
Each of the display pixels of red, green, and blue in each unit pixel is displayed based on a display signal sampled simultaneously.

  According to the present invention, it is possible to provide a display device capable of improving the visual resolution.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

[First Embodiment]
FIGS. 1A and 1B schematically show the display pixel areas constituting one unit pixel of the liquid crystal display device as the first embodiment of the display device of the present invention and the functions of reproduced colors of each display pixel. FIG. 1A is a plan view of one unit pixel, and FIG. 1B is a plan view showing an arrangement of a plurality of unit pixels. FIG. 2 shows the display pixel transmittance (the product of the transmittance of the display pixel and the gradation value (in this example, the product of the unit pixel A is 1 and the unit pixel B is 0) itself) and is smoothed in terms of visual perception. It is a figure which shows the distribution of the transmittance | permeability, R, G, B, W described on the horizontal axis shows a red display pixel, a green display pixel, a blue display pixel, and a white display pixel.

  Here, the display based on the display signal sampled at the same time is performed on the red display pixel, the green display pixel, and the blue display pixel in each unit pixel.

  As in the prior art, in this embodiment, as shown in FIG. 1A, one unit pixel 10 for performing color display is divided into red (R), green (G), blue (B), and white (W ) Four display pixels 12. A large number of the unit pixels 10 are arranged on the display surface to form an effective display area as shown in FIG. 1B (in FIG. 1B, each unit pixel 10 is surrounded by a thick frame). ). The area of each display pixel 12 is the same, and each occupies 1/4 of one unit pixel 10.

  However, in the first embodiment of the present invention, the green display pixel 12G and the white display pixel 12W are arranged in the center of the unit pixel 10, for example, as shown in FIG. In order from the left, red (red display pixel 12R), green (green display pixel 12G), white (white display pixel 12W), and blue (blue display pixel 12B).

  By arranging the display pixels 12 in this order, (Dr, Dg, Db) = (255, 255, 255) as described above with reference to FIGS. 10 (A) and 10 (B). Unit pixel A and (Dr, Dg, Db) = (0, 0, 0) unit pixel B are adjacent to each other on the left and right, and the unit pixel adjacent to the left side of unit pixel A is the same as unit pixel A ( Dr, Dg, Db) = (255, 255, 255), and the unit pixel adjacent to the right side of the unit pixel B is the same as the unit pixel B (Dr, Dg, Db) = (0, 0, 0), In the first embodiment, the transmittance for each display pixel in the two unit pixels A and B is 4.7%, 13.2%, 18.0%, 3.5%, 0. 0%, 0.0%, 0.0%, 0.0%, and the luminous transmittance distribution is 9.1%, 10.2%, 9. %, 6.5%, 2.9%, 0.8%, 0.1%, 0.0%, and as shown in FIG. 2, with respect to the region of the unit pixel B that should originally display black The influence of the adjacent unit pixel A is reduced as compared with the conventional case (see FIG. 11).

  Therefore, according to the first embodiment, it is possible to obtain a more faithful display especially at the unit pixel boundary where the luminance greatly changes, and the visual resolution is improved.

  The arrangement of the unit pixels 10 is not limited to a stripe arrangement in which the display pixels 12 of the same color are aligned in a line in the vertical direction as shown in FIG. 1B, but an even number as shown in FIG. The parallelogram array is a parallelogram-type array in which the sampling of the rows and the odd-numbered rows is shifted by a half pitch, and the array of the unit pixels 10 is shifted by two display pixels as indicated by the parallelogram 14. However, the same effect can be obtained.

  The arrangement of the display pixels 12 is not limited to the order of the red display pixels 12R, the green display pixels 12G, the white display pixels 12W, and the blue display pixels 12B in order from the left as shown in FIG. And the green display pixel 12 </ b> G may be arranged in the center of the unit pixel 10. That is, in order from the left as shown in FIG. 4A, the order of the blue display pixel 12B, the green display pixel 12G, the white display pixel 12W, and the red display pixel 12R, and the red display pixel 12R as shown in FIG. , White display pixel 12W, green display pixel 12G, blue display pixel 12B, blue display pixel 12B, white display pixel 12W, green display pixel 12G, red display pixel 12R as shown in FIG. Similar effects can be obtained.

  Further, when the unit pixel 10 is divided into the display pixels 12, it is divided into four in the left and right directions, but the same effect can be obtained by dividing into four in the vertical direction.

  As described above, according to the first embodiment, the green display pixel 12G and the white display pixel 12W are arranged in the center of the unit pixel 10 to reduce the influence between the adjacent unit pixels 10 and to Sensitive resolution can be improved.

  FIG. 5A is a block diagram illustrating a schematic configuration of a driving unit in the liquid crystal display device according to the first embodiment, and FIG. 5B is a block diagram illustrating an essential part thereof.

  As shown in FIG. 5A, this liquid crystal display device includes a scanning line 16, a signal line 18, a liquid crystal display panel 20, a controller 22, a liquid crystal driving power supply circuit 24, a vertical scanning circuit 26, a video signal driving circuit 28, and the like. It is configured. In the drawing, the reference potential is required in an active matrix liquid crystal display device, and is not necessary when applied to a simple matrix liquid crystal display device.

  Display data (gradation values (Dr, Dg, Db)) and control signals are formed by the controller 22 based on display data input from the CPU 30 such as a host computer to the liquid crystal display device. (Here, an example including the CPU 30 will be described. However, even if the configuration is appropriately changed depending on the system, it does not matter to the essence of the invention.) The liquid crystal display panel 20 has 4 unit pixels as described above on the entire display area. A large number of pixels composed of color display pixels 12R, 12G, 12B, and 12W are formed. Display data output from the controller 22 is applied to a video signal drive circuit 28 together with a control signal, and is supplied to a switching element (not shown) of each display pixel via a signal line 18. The control signal is also applied to the vertical scanning circuit 26 and is applied to the scanning electrode of each pixel via the scanning line 16.

  In such a pixel configuration, a configuration for supplying a display signal to the display pixel 12W for white display is necessary. Therefore, as shown in FIGS. 5A and 5B, a gradation calculation circuit 32 for calculating a gradation value to be actually displayed is provided between the controller 22 and the video signal driving circuit 28. Gradation values (D'r, D'g, D'b, D) input to the display pixels 12R, 12G, 12B, 12W of red, green, blue, and white from the gradation values (Dr, Dg, Db) of 'w) is being calculated. As the calculation method, the method disclosed in Patent Document 1 can be applied.

  For example, the three primary colors of red, green, and blue are used as they are, and the gradation value (D′ w) of white W is input to each display pixel corresponding to the three primary colors of red, green, and blue. The smallest value among the two gradation values is set.

  The video signal driving circuit 28 and the gradation calculation circuit 32 are integrally formed on the substrate on which the signal lines 18 are formed, so that the video signal driving circuit 28 is manufactured in the TFT manufacturing process for manufacturing the switching element of each display pixel. Since it can be formed simultaneously with the switching element, the cost can be reduced. Further, the video signal drive circuit 28 has a circuit size of 4/3 as compared with the case of three colors of RGB. However, when the image signal drive circuit 28 is integrally formed on the substrate, the process and cost are hardly increased. Therefore, in this case, the function of the present invention can be realized without increasing the cost.

  Note that the gradation values (D′ r, D′ g, D′ b, D′ w) input to each display pixel are based on the gradation values (Dr, Dg, Db, Dw) input to RGB. It may be determined by changing the rules as appropriate. In this case, the user can control the white color temperature by changing the rule. In this case, it is desirable that the user can control the rule from outside the liquid crystal display element by a hardware or software mechanism.

[Second Embodiment]
Next, a second embodiment of the present invention will be described.

  FIG. 6 is a plan view of one unit pixel in a liquid crystal display device as a second embodiment of the display device of the present invention. FIG. 7 is a diagram showing display pixel transmittance and luminous transmittance distribution. R, W, G, and B shown on the horizontal axis are red display pixels 12R, white display pixels 12W, and green display pixels. 12G, blue display pixel 12B is shown.

  In the present embodiment, one unit pixel 10 for performing color display is composed of four display pixels 12 of red, green, blue, and white, and the arrangement of the display pixels in the unit pixel 10 is a red display pixel 12R. For example, as shown in FIG. 6, the red display pixel 12R, the white display pixel 12W, the green display pixel 12G, and the blue display pixel 12B are arranged in this order from the left.

  By arranging the display pixels 12 in this order, for example, when displaying a uniform yellow color, the gradation values (Dr, Dg, Db) of (red, green, blue) = (255, 255, 0). However, in such a case, when displaying on a liquid crystal display device having a display pixel arrangement of red, green, blue, and white in order from the left in the conventional case, as described above with reference to FIG. The distribution of the display pixel transmittance within the unit pixel is 4.7%, 13.2%, 0.0%, and 0.0% in order from the left, whereas in the second embodiment, the left (D′ r, D′ w, D′ g, D′ b) = (255, 0, 255, 0), and the unit pixel 10 is arranged in the order of red, white, green, and blue. As shown in FIG. 7, the distribution of the display pixel transmittance is 4.7%, 0.0%, 13.2%, and 0.0% in order from the left.

  Therefore, in the case of FIG. 7 as compared with FIG. 12, the spatial frequency of the luminance is a reciprocal of ½ of the width of one unit pixel 10, which reduces the phenomenon in which yellow and black appear alternately, It can be seen that the resolution is improved.

  Note that the arrangement of the unit pixels 10 may be a stripe arrangement or a parallelogram arrangement, as in the first embodiment.

  The arrangement of the display pixels 12 is not limited to the order of the red display pixels 12R, the white display pixels 12W, the green display pixels 12G, and the blue display pixels 12B in order from the left as shown in FIG. What is necessary is just to arrange | position apart from the pixel 12G. That is, the order of the white display pixel 12W, the green display pixel 12G, the blue display pixel 12B, and the red display pixel 12R as shown in FIG. 8A, the green display pixel 12G and the blue display pixel as shown in FIG. 12B, red display pixel 12R, white display pixel 12W, order blue display pixel 12B, red display pixel 12R, white display pixel 12W, green display pixel 12G as shown in FIG. 8C, FIG. 8D. The order of the blue display pixel 12B, the green display pixel 12G, the white display pixel 12W, and the red display pixel 12R as shown in FIG. 8, the green display pixel 12G, the white display pixel 12W, the red display pixel 12R, as shown in FIG. The order of the blue display pixel 12B, the order of the white display pixel 12W, the red display pixel 12R, the blue display pixel 12B, and the green display pixel 12G as shown in FIG. 8F, the red display pixel as shown in FIG. 12R, blue display pixel 12B, green示画 element 12G, the order of the white display pixel 12W, but the same effect can be obtained.

  The red display pixel 12R and the green display pixel 12G are arranged apart from each other in order from the left as shown in FIG. 9A, such as a red display pixel 12R, a blue display pixel 12B, a white display pixel 12W, The order of the green display pixel 12G, the order of the red display pixel 12R, the white display pixel 12W, the blue display pixel 12B, and the green display pixel 12G as shown in FIG. 9B, the green display pixel as shown in FIG. 9C. 12G, blue display pixel 12B, white display pixel 12W, red display pixel 12R, and green display pixel 12G, white display pixel 12W, blue display pixel 12B, red display pixel 12R as shown in FIG. 9D. , Also exists. In each unit pixel 10, the red display pixel 12R and the green display pixel 12G are arranged apart from each other. However, between the two adjacent unit pixels 10, the red display pixel 12R and the green display pixel 12G are separated from each other. Adjacent to each other. Therefore, such an arrangement is excluded.

  Further, when the unit pixel 10 is divided into the display pixels 12, it is divided into four in the left and right directions, but the same effect can be obtained by dividing into four in the vertical direction.

  The configuration of the driving means in the liquid crystal display device of the second embodiment is the same as that of the first embodiment described with reference to FIGS. 5 (A) and 5 (B).

  As described above, according to the second embodiment, the human eyes are sensitive by disposing the red display pixel 12R and the green display pixel 12G in the one unit pixel 10 and between the adjacent unit pixels 10 apart from each other. When displaying a flesh-colored to yellowish color, the spatial resolution of the luminance can be increased to improve the visual resolution.

  The first and second embodiments have been described on the assumption that the unit pixel 10 is sampled for each color at the same time. However, the second embodiment does not require such simultaneous sampling, that is, the sampling time. Even if the colors are different for each color, the same effect can be obtained.

  The present invention has been described above based on the embodiments. However, the present invention is not limited to the above-described embodiments, and various modifications and applications are possible within the scope of the gist of the present invention. .

  In the above description, the case where each color has the maximum gradation and the minimum gradation has been described for the sake of easy understanding, but the same effect can be obtained even in the case of a halftone.

  The configuration in which the red display pixel 12R and the green display pixel 12G as in the second embodiment are arranged apart from each other in the one unit pixel 10 and between the adjacent unit pixels 10 is the white display pixel 12W of the first embodiment. And the green display pixel 12G may be combined and arranged in the center of the unit pixel 10 (corresponding to the arrangement in FIGS. 6 and 8D). By doing so, the effect of both embodiment can be show | played.

  Moreover, although the said 1st and 2nd embodiment demonstrated the liquid crystal display device as an example, it is applicable also to the display device using light emitting elements, such as EL which employ | adopted the filter system.

(A) is a top view of 1 unit pixel in the liquid crystal display device as 1st Embodiment of the display apparatus of this invention, (B) is a top view which shows arrangement | positioning of several unit pixel. It is a figure which shows distribution of the display pixel transmittance | permeability at the time of the display data shown in FIG.10 (B) being input in the liquid crystal display device of 1st Embodiment, and the transmittance | permeability smoothed on visual perception. It is a top view which shows arrangement | positioning of the several unit pixel at the time of setting it as a parallelogram arrangement. (A) thru | or (C) is a top view for demonstrating another example of arrangement | positioning of the display pixel in 1 unit pixel in 1st Embodiment, respectively. FIG. 2A is a block diagram illustrating a schematic configuration of a driving unit in the liquid crystal display device of the first embodiment, and FIG. 2B is a block diagram illustrating a main part extracted. It is a top view of 1 unit pixel in the liquid crystal display device as 2nd Embodiment of the display apparatus of this invention. It is a figure which shows distribution of the display pixel transmittance | permeability when the display data for displaying uniform yellow in the liquid crystal display device of 2nd Embodiment are input, and the smoothing transmittance | permeability on visual appearance. (A) thru | or (G) is a top view for demonstrating another example of arrangement | positioning of the display pixel in 1 unit pixel in 2nd Embodiment, respectively. (A) thru | or (D) is a top view for demonstrating the example of arrangement | positioning of the display pixel in 1 unit pixel excluded in 2nd Embodiment, respectively. (A) is a figure which shows the positional relationship of the unit pixels in the conventional display apparatus, (B) is a figure which shows the input image data. It is a figure which shows distribution of the display pixel transmittance | permeability at the time of the display data shown in FIG.10 (B) being input in the conventional display apparatus, and the transmittance | permeability smoothed on visual perception. It is a figure which shows distribution of the display pixel transmittance | permeability at the time of the display data for displaying uniform yellow in the conventional display apparatus being input, and the transmittance | permeability smoothed on visual perception.

Explanation of symbols

    DESCRIPTION OF SYMBOLS 10 ... Unit pixel, 12 ... Display pixel, 12R ... Red display pixel, 12G ... Green display pixel, 12B ... Blue display pixel, 12W ... White display pixel, 14 ... Parallelogram, 16 ... Scanning line, 18 ... Signal line, DESCRIPTION OF SYMBOLS 20 ... Liquid crystal display panel, 22 ... Controller, 24 ... Liquid crystal drive power supply circuit, 26 ... Vertical scanning circuit, 28 ... Video signal drive circuit, 30 ... CPU, 32 ... Gradation operation circuit.

Claims (5)

A display device in which a plurality of display pixels are arranged in a matrix and each unit pixel for performing color display is composed of four display pixels of red, green, blue, and white,
Within one unit pixel, the four display pixels are arranged in a line,
A display device, wherein a green display pixel and a white display pixel are arranged adjacent to each other in the center of the one unit pixel.   2. The display device according to claim 1, wherein each of the display pixels of red, green, and blue in each unit pixel is displayed based on a display signal sampled at the same time.   The display device according to claim 1, wherein the red display pixel and the green display pixel are arranged apart from each other in one unit pixel and between adjacent unit pixels. A display device in which a plurality of display pixels are arranged in a matrix and each unit pixel for performing color display is composed of four display pixels of red, green, blue, and white,
In one unit pixel, the four display pixels are arranged in a line,
A display device, wherein a red display pixel and a green display pixel are arranged separately in one unit pixel and between adjacent unit pixels.   The display device according to claim 4, wherein display is performed on the display pixels of red, green, and blue in each unit pixel based on display signals sampled simultaneously.

Images