JP2005141240A - Liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display (1) which can display in a wide color reproducibility range, (2) which can display with saved power consumption at a low cost, (3) which enables improved color reproduction reflecting human visual characteristics thereon, and (4) which can constantly output a white color. <P>SOLUTION: A microfilter constituting a color filter 3 has four colors corresponding to an R-G axis and a B-Y axis reflecting the opponent colors as human visual characteristics. An irradiation light 2 is for emitting white light including a peak in the wavelength region of the microfilter. A signal processing section 4 converts the input color image signal into a color component signal of the microfilter. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a color liquid crystal display device used as a monitor such as a personal computer or a word processor, and further as a display or projector such as a television receiver, and more particularly to a liquid crystal display device capable of color reproduction in a wide color range. It is.

  In recent years, the resolution of liquid crystal panels has increased due to advances in microfabrication technology, and low-voltage drive has been applied to information equipment displays centered on personal computers (PCs) and video equipment displays centered on television receivers and projectors. Demand for liquid crystal display devices characterized by thinness and light weight is increasing.

  Along with the above-mentioned increase in resolution, color display technology for liquid crystal panels is also being developed. As a method, a single-panel color filter method in which RGB filters corresponding to each pixel of the liquid crystal panel are arranged in front of or behind the liquid crystal panel, or a liquid crystal panel is provided for each RGB image, and an RGB back is provided for each liquid crystal panel. There are three panel systems for supplying light or front light.

  In both systems, a color image for each RGB component is displayed and formed, and these are additively mixed to display a full color image. The single-panel color filter method is small and light, and is widely used as a PC monitor and liquid crystal TV. In addition, the three-panel method is applied to a liquid crystal projector and the like because an apparatus scale becomes large but a high-resolution and high-luminance video can be obtained.

  As described above, since the colorization of the conventional liquid crystal display device is performed by the color filters of the three primary colors of RGB, the color gamut of the device is determined by their chromaticity. When this color reproduction range is expressed on the chromaticity diagram, it is as shown in FIG.

  In FIG. 9, R, G, and B are the chromaticity coordinates of the three primary colors used in the color filter of the liquid crystal display device, and the outer horseshoe-shaped locus indicates monochromatic light (spectrum) that can be perceived by humans. The inside of the horseshoe shows the range of colors that humans can perceive.

  A liquid crystal display device using R, G, B color filters can reproduce the color inside the triangle formed by the chromaticity coordinates R, G, B. As is clear from FIG. 9, the color reproduction range that can be expressed by the conventional liquid crystal display device is smaller than the color reproduction range that can be perceived by humans, and the enlargement is an important problem in promoting higher image quality. It has become.

  To deal with such a problem, for example, Patent Document 1 discloses a reflective liquid crystal display device using Y (yellow), M (magenta), and C (cyan) as primary colors used in subtractive color mixing such as printing. Yes.

  In this device, it is effective when a bright image is required like a reflective liquid crystal, but red, which is said to be involved in the opposite color characteristics of the visual system, that is, the color appearance such as human “brilliance”, There is a problem that the green and blue display cannot be vivid.

  Further, in Patent Document 2, in addition to the light emitting portions of the three primary colors of R, G, and B, a color provided with a fourth color forming portion having a light emission characteristic having a wavelength range of a red negative sensitivity portion indicated by Gr in FIG. A video system is disclosed.

According to this, by setting the fourth chromaticity point Gr having the wavelength range of the red negative sensitivity portion, it is possible to display a portion surrounded by the chromaticity points R, G, B, and Gr. . It has also been suggested that a liquid crystal display device may be configured by providing fine color filters that emit light of the four colors.
JP-A-10-307205 Japanese Patent Laid-Open No. 3-92888

  However, the above-described conventional technology also has the following two problems. First, it is not a problem with a self-luminous display device that emits a phosphor such as a CRT, but it has been realized with a non-luminous display device that controls transmitted light or reflected light (hereinafter referred to as irradiation light) of a liquid crystal panel. In this case, there is a problem that the color cannot be expressed unless the color component is included in the irradiation light.

  If the irradiation light covers the wavelength region (400-700 nm) of the visible light region, it is possible to display, but in that case, it is necessary to use a large light with high power consumption. There's a problem.

  Second, there is a problem that it is not well adapted to human visual characteristics. That is, when the xy chromaticity in FIG. 9 is converted into a color matching color space adapted to human visual characteristics, a color matching color space chromaticity diagram shown in FIG. 10 is obtained.

  The uniform color space indicates a difference in color perceived by humans as a distance on the chromaticity diagram, and a portion indicated by A in FIG. 10 indicates that humans can perceive many different colors. Has been.

  Furthermore, in recent years, focusing on color appearance, the opposite color response, which is said to occur in the process in which visual signals are carried to the cerebrum, is being elucidated. This phenomenon is such that red and green are not perceived at the same place and at the same time, and blue and yellow are not perceived at the same place and at the same time.

  These red and green, blue and yellow are called opposite colors and are unique colors that cannot be further divided. By reflecting the characteristics on the display device, it is possible to display an image close to the actual appearance, but an image display technique using the opposite color has not been proposed yet.

  Another problem with conventional display devices is that the white color is not constant. White is a standard color in terms of human color perception. If white has a tint, vision adapts to that tint and the balance of color perception is lost. Therefore, displaying white accurately is important for making the color appearance constant.

  However, as described above, when R, G, and B colors are mixed and expressed, there is a possibility that white may be tinted, which hinders high image quality.

  The present invention has been made in view of the above problems, and (1) provides a liquid crystal display device capable of displaying a wide color reproduction range. (2) Further, the display can be realized with low power consumption and low cost. (3) Further, it is possible to provide a liquid crystal display device that can improve color reproduction reflecting human visual characteristics, and (4) can output a constant white color.

  According to a first aspect of the present application, there is provided a liquid crystal panel, a signal processing unit that converts an input color video signal into a driving signal for the liquid crystal panel, an irradiation light that irradiates the liquid crystal panel to generate an image, and the liquid crystal A liquid crystal display device comprising a color filter composed of four or more color filters corresponding to the pixels of the panel, and a color filter for full-coloring an image formed by the liquid crystal panel by additive color mixing. It has four colors corresponding to the RG axis (red / green axis) and the BY axis (blue / yellow axis) reflecting the opposite colors as the characteristics, and the irradiation light is in the wavelength region of the fine filter. Irradiating white light having a peak, and the signal processing unit converts an input color video signal into a color component signal of the fine filter.

  Thus, by using the four fine color filters, the color reproduction range can be expanded, and the color appearance reflecting the opposite color response of human visual characteristics can be improved. Furthermore, since the irradiation light emits light having a peak in the wavelength region of each fine filter, efficient irradiation is possible, and high image quality, low power consumption, and cost reduction can be realized.

  In the second invention of the present application, the fine filter has four colors corresponding to the RG axis (red-green axis) and the BY axis (blue-yellow axis) reflecting the opposite colors that are human visual characteristics. It is characterized by having five colors including white.

  As a result, an independent white filter is provided in addition to the four color filters corresponding to the RG axis and the BY axis, so that the white color can be made constant and the balance of color perception can be maintained. Can do.

  According to a third aspect of the present invention, the signal processing unit is a liquid crystal panel that selects two colors from the fine filter according to the input color of each pixel, and displays the colors by the selected two colors and white. It is characterized by generating a drive signal.

  As a result, red and green, and blue and yellow are not displayed at the same place and at the same time, so that a good color display reflecting the opposite color response can be performed.

  According to a fourth aspect of the present invention, there is provided a liquid crystal panel, a signal processing unit that converts an input color video signal into a driving signal for the liquid crystal panel, an irradiation light that irradiates the liquid crystal panel to generate an image, and the liquid crystal A liquid crystal display device comprising a color filter composed of four or more color filters corresponding to the pixels of the panel, and a color filter for full-coloring an image formed by the liquid crystal panel by additive color mixing, wherein the fine filter is an RGB 3 It has four colors obtained by adding magenta to a primary color, the irradiation light irradiates white light having a peak in the wavelength region of the fine filter, and the signal processing unit receives an input color video signal. It converts to the color component signal of the fine filter.

  As a result, since the display device can be improved from the conventional display device, the design cost can be reduced and compatibility with the conventional display device can be obtained. Furthermore, the color reproduction range on the color matching color space reflecting human visual characteristics can be expanded, and the color appearance can be improved.

  According to the present invention, by using four fine color filters corresponding to the RG axis (red / green axis) and the BY axis (blue / yellow axis) reflecting colors opposite to human visual characteristics, It is possible to expand the reproduction range, and further, by irradiating light having a peak in the wavelength region of the color filter, efficient irradiation is possible, and low power consumption and cost reduction can be realized.

  Alternatively, it is possible to improve the conventional display device by using a four-color fine filter in which magenta is added to the three RGB colors used in conventional color display, thus reducing the design cost. In addition, compatibility with conventional display devices can be obtained. Furthermore, the color reproduction range on the color matching color space reflecting human visual characteristics can be expanded, and the color appearance can be improved.

  Hereinafter, a liquid crystal display device according to a first embodiment of the present invention will be described in detail with reference to FIGS.

  FIG. 1 is a block diagram showing a schematic configuration of the present embodiment. In FIG. 1, 1 is a liquid crystal panel that forms a desired image, 2 is a backlight that is disposed behind the liquid crystal panel 1 and irradiates the liquid crystal panel 1, and 3 is disposed on the front surface of the liquid crystal panel 1. A color filter 4 for colorizing an image formed by the liquid crystal panel 1 by additive color mixing is a signal processing unit 4 that converts an input color video signal into a drive signal for the liquid crystal panel 1.

  The signal processing unit 4 includes a signal conversion unit 12 and a liquid crystal drive circuit unit 13, and the liquid crystal drive circuit unit 13 includes a signal electrode drive circuit 15 and a scan electrode drive circuit 16.

  FIG. 2 is an enlarged explanatory view showing the configuration of the color filter 3. As shown in FIG. 2, the color filter 3 includes red (R), green (G), blue (B), and yellow (Y) fine filters arranged in correspondence with each pixel of the liquid crystal panel 1. It becomes the composition.

  FIG. 2A shows an arrangement in which R and B are in one row and Y and G are in one row. In FIG. 2B, R, B, Y, and G form one row, and the following 2 An arrangement in which columns shifted by pixels continues is shown. In the present embodiment, the configuration of the two examples shown in FIGS. 2A and 2B has been described. However, the arrangement is not limited to these two, and various arrangements are possible.

  FIG. 3 is an XY chromaticity diagram showing the chromaticities of red (R), green (G), blue (B), and yellow (Y) shown in FIG. In FIG. 3, R, G, B, and Y indicate the chromaticity of the fine filter. The dotted lines 5 and 6 in FIG. 3 indicate the RG axis and YB axis, which are axes of opposite colors, which are characteristics of the human visual system. For example, the RG axis 5 has a green point around 500 nm and a white point. 7, the YB axis 6 is an axis connecting yellow near 570 nm and blue 480 nm.

  Here, the intersection of the RG axis 5 and the YB axis 6 indicates a white point. In addition, the numerical value of said axis | shaft is an example and is not restricted to this numerical value. As shown in FIG. 2, the chromaticities of red (R) and green (G) in the fine color filter are blue (B) in the fine color filter at two points sandwiching the white point 7 on the RG axis 5. , Yellow (Y) chromaticity is set to two points sandwiching the white point 7 on the YB axis 6.

  The red (R), green (G), and blue (B) described above differ in chromaticity from the RGB values in NTSC. The method for setting each chromaticity is preferably set at the extreme end of the axis as much as possible in consideration of the relationship between the transmission amount and density of the dye used when coloring the color filter.

  FIG. 4 shows an emission spectrum of the backlight 2, and is a graph in which the horizontal axis represents wavelength (nm) and the vertical axis represents relative radiation intensity. As shown in FIG. 4, the backlight 2 is a fluorescent lamp in which phosphors having peaks in the respective wavelength regions of the four colors of the fine color filter that have been operated are applied in the bulb surface.

  In FIG. 4, 8 is light in the blue wavelength region having a peak near 480 nm, 9 is light in the green wavelength region having a peak near 500 nm, 10 is light in the yellow wavelength region having a peak near 570 nm, 11 Is light in the red wavelength region having a peak near 640 nm.

  Hereinafter, the operation of the liquid crystal display device of this embodiment will be described. The input video signal is converted into red (R), green (G), blue (B), and yellow (Y) components of the fine filters constituting the color filter 3 by the signal conversion unit 12 of the signal processing unit 4. Is converted to

  This conversion uses video data obtained by sampling the video signal for each pixel by simple linear conversion such as matrix conversion, or a method of referring to a look-up table (LUT) to improve accuracy. Can do.

  The converted R, G, B, and Y color component signals are converted into liquid crystal drive signals by the liquid crystal drive circuit unit 13 to drive the liquid crystal panel 1. The scan electrode driving circuit 16 is composed of a shift register circuit, and its output is output from the horizontal line transparent electrode to the gate of the TFT connected in parallel in the horizontal direction on the liquid crystal panel 1.

  The signal electrode driving circuit 15 is composed of a shift register circuit and a sample and hold circuit, and its output is connected from the vertical line transparent electrode to the drain or source of TFTs arranged vertically on the liquid crystal panel 1. When a scanning signal is applied to the gates of these TFTs, the source / drain is electrically connected.

  Here, when a video signal is applied to the source or drain, the liquid crystal layer is charged and applied. The applied charge is held until the next scanning signal is given. That is, the scanning electrode driving circuit 16 turns on the TFTs in the horizontal direction all at once, and the signal electrode driving circuit 15 in the meantime passes red (R), green (G), blue (B), and yellow (Y) for one line. Is written in the intersection pixel of each corresponding electrode.

  By sequentially scanning in the vertical direction, video information of red (R), green (G), blue (B), and yellow (Y) is applied to the liquid crystal panel 1 as a video signal voltage. Since the amount of light transmitted through the liquid crystal layer varies depending on the voltage applied to the liquid crystal layer, the amount of light transmitted through the backlight 2 is controlled by the video signal voltage to form an image.

  The image formed on the liquid crystal panel 1 is colored into four colors by the fine color filters of red (R), green (G), blue (B), and yellow (Y), and as a full-color image by the principle of additive color mixing. Visible to viewers.

  Here, the image irradiated on the backlight 2 and formed on the liquid crystal panel 1 has the emission spectrum described above with reference to FIG. Accordingly, when the color is formed by the four fine color filters, the amount of light that is filtered and absorbed is small, in other words, the light use efficiency is improved, so that the power can be saved.

  Furthermore, since the full-color image displayed by the display device of the present embodiment can represent the color reproduction range 17 connecting the four points R, G, B, and Y shown in FIG. It is possible to express colors that could not be expressed in the range.

  In the above embodiment, the four fine color filters are red (R), green (G), blue (B), and yellow (Y), but may be configured with other chromaticities. An example of chromaticity is shown in the UV chromaticity diagram of the uniform color space in FIG. Here, the uniform color space is a color space in which a human-perceived color difference is matched with a distance on a chromaticity diagram, and is used as a good representation of human color characteristics.

  In FIG. 5, R1, G1, and B1 indicate the chromaticities of the three primary color filters used in the conventional liquid crystal display device. R1, G1, and B1 are originally defined from the luminous efficiency of the phosphor used to display the color on the CRT display, and are also used in the liquid crystal display device in consideration of compatibility.

  In FIG. 5, M is the chromaticity of the fourth color filter added in this example, and as is clear from FIG. 5, a position that covers colors that cannot be represented by the current three primary colors, specifically magenta. It is set near the color of.

  With this configuration, it is possible to expand the color reproduction range in consideration of human visual characteristics, and furthermore, it is possible to use and improve the three primary colors of color filters used in conventional liquid crystal display devices, so the design development cost Can be reduced.

  Next, a liquid crystal display device according to a second embodiment of the present invention will be described with reference to FIGS. 6 to 8. The same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. Here, FIG. 6 is a block diagram showing a schematic configuration of the present embodiment, and FIG. 7 is an XY chromaticity diagram showing the chromaticity of the color filter constituting the present embodiment.

  In the liquid crystal display device of the present embodiment, the color filter 23 differs from that of the first embodiment in that the color filter 23 is red (R), green (G), blue (B), yellow (as shown in FIG. The point where white (W) is added to the four colors Y), and the signal converter 32 converts the input color video signal into red (R), green (G), blue (B), and yellow (Y). This is a point to be converted into five color components of white (W).

  According to the configuration of the present embodiment, by providing an independent white fine filter, it is possible to display a constant achromatic color (white), and it is possible to realize a color display with a balanced color perception. It is.

  Further, the operation of the signal converter 32 will be described with reference to the flowchart of FIG. First, when a color video signal is input (S1), the input color video signal is sampled for each pixel, and a chromaticity value (x, y) of each pixel is calculated. The processes from S3 to S15 are repeated for each pixel.

  First, the presence / absence of color components is determined (S3). If there is no color component (achromatic color), only the white component signal is output in S4, the other four colors are not output, or a signal of "0" (not displayed) is output.

  If there is a color component, in S5, S8, and S11, it is determined where the color component is located in the regions 18, 19, 20, and 21 in the chromaticity diagram of FIG.

  In the case of being located in the region 18 in FIG. 7, the conversion using the three primary colors B, G, and W constituting the region 18 is performed in S6, and the B component signal, the G component signal, and the W component signal are output in S7. (R and Y signals are not output or “0” is output).

  Similarly, when the color components are in the regions 19, 20, and 21, the conversion using B, R, and W as the three primary colors in S9, S10, or S12, S13, or S14, and S16, respectively, R, Y, and W are set to 3 Conversion using primary colors, conversion using G, Y, and W as three primary colors, and signal output processing are performed.

  As described above, after determining whether the color component is included in any of the regions 18, 19, 20, and 21, the colors are displayed by the color component signals constituting the region, so that red and green or blue And yellow are not displayed at the same place and at the same time, and color display close to the actual appearance reflecting the opposite color response becomes possible.

It is a block diagram which shows schematic structure of 1st Embodiment of the liquid crystal display device of this invention. FIG. 3 is an enlarged explanatory view showing a configuration of a color filter in the first embodiment of the liquid crystal display device of the present invention. It is an XY chromaticity diagram showing the chromaticity of the fine filter (red, green, blue, yellow) in the first embodiment of the liquid crystal display device of the present invention. It is explanatory drawing which shows the emission spectrum of the backlight in 1st Embodiment of the liquid crystal display device of this invention. It is a color matching space color chromaticity diagram showing the chromaticity of other fine filters (red, green, blue, magenta) in the first embodiment of the liquid crystal display device of the present invention. It is a block diagram which shows the structure of 2nd Embodiment of the liquid crystal display device of this invention. It is XY chromaticity diagram which shows the chromaticity of the fine filter (red, green, blue, yellow, white) in 2nd Embodiment of the liquid crystal display device of this invention. It is a flowchart which shows operation | movement of the signal conversion part in 2nd Embodiment of the liquid crystal display device of this invention. It is xy chromaticity diagram for demonstrating a prior art. It is a color matching space color chromaticity diagram for explaining the prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid crystal panel 2 Backlight 3 Color filter 4 Signal processing part 5 Signal conversion part 13 Liquid crystal drive circuit part 15 Signal electrode drive circuit 16 Scan electrode drive circuit 23 Color filter-
32 Signal converter

Claims (4)

A liquid crystal panel; a signal processing unit that converts an input color video signal into a driving signal for the liquid crystal panel; an illumination light that irradiates the liquid crystal panel to generate an image; and four colors corresponding to pixels of the liquid crystal panel A liquid crystal display device comprising the above-described fine filter, and a color filter that makes the image formed by the liquid crystal panel full color by additive color mixing,
The fine filter has four colors corresponding to the RG axis and the BY axis reflecting opposite colors that are human visual characteristics, and the irradiation light has a peak in the wavelength region of the fine filter. A liquid crystal display device characterized by irradiating white light, wherein the signal processing unit converts an input color video signal into a color component signal of the fine filter. The liquid crystal display device according to claim 1,
The fine filter has five colors obtained by adding white to four colors corresponding to an RG axis and a BY axis reflecting opposite colors that are human visual characteristics. Liquid crystal display device. The liquid crystal display device according to claim 2,
The signal processing unit selects two colors from the fine filter in accordance with the input color of each pixel, and generates a driving signal for a liquid crystal panel that displays the color with the selected two colors and white. A liquid crystal display device as described above. A liquid crystal panel; a signal processing unit that converts an input color video signal into a driving signal for the liquid crystal panel; an illumination light that irradiates the liquid crystal panel to generate an image; and four colors corresponding to pixels of the liquid crystal panel A liquid crystal display device comprising the above-described fine filter, and a color filter that makes the image formed by the liquid crystal panel full color by additive color mixing,
The fine filter has four colors obtained by adding magenta to three primary colors of RGB, and the irradiation light irradiates white light having a peak in a wavelength region of the fine filter, and the signal processing The unit converts an input color video signal into a color component signal of the fine filter.

Images