JP2006259585A - Color liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color liquid crystal display device capable of display with a wide color range. <P>SOLUTION: The color liquid crystal display device 100 comprises a transmission type color display panel 10 with a color filter and a back light source 20, wherein the back light source 20 is equipped with a fluorescent lamp 21 with a wide color reproduction range and the color filter 19 comprises a primary-color color filter transmitting red light, green light, and blue light by wavelength selection and complementary color filters of one or more colors. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a color liquid crystal display device comprising a color liquid crystal display panel and a backlight source for liquid crystal display that illuminates the color liquid crystal display panel from the back side.

2. Description of the Related Art In recent years, displays (image display devices) have been made thinner as represented by liquid crystal display devices (LCDs) and PDPs (plasma display panels).
In particular, a color liquid crystal display device using a color liquid crystal display panel can be driven with low power consumption, and further development in the future can be expected as the price of a large color liquid crystal panel is reduced.

A color liquid crystal display device is mainly a so-called backlight method in which a color image is displayed by illuminating a transmissive color liquid crystal display panel with a backlight device from the back side.
As a light source of the backlight device, a CCFL (cold cathode fluorescent tube) that emits white light using a fluorescent tube is often used (see, for example, Patent Document 1).

  The sRGB standard defined as a standard color space for computer displays is based on the Rec. ITU recommendation for the chromaticity points of the three primary colors RGB. The relationship between the video signal RGB and the colorimetric values is clearly defined by matching with the color measurement parameters 709, and the same video signal RGB can be given to a display (image display device) compliant with the sRGB standard. Thus, the same color can be displayed colorimetrically.

Incidentally, a video device that receives and displays color information captured by a camera or a scanner, that is, a display or a printer, needs to display the received color information accurately.
For example, even if the camera accurately acquires color information, the color reproducibility of the entire system deteriorates due to display of inappropriate color information on the display.

  In recent years, as represented by liquid crystal TVs and PDPs, displays are becoming thinner, and among them, most mobile displays mainly use liquid crystal panels. Also in this liquid crystal panel, faithful color reproducibility is desired.

  Display on the current standard monitor is defined in the color gamut of the sRGB standard described above, but there are many colors that exceed the color gamut of sRGB in the world, and there are object colors that cannot be displayed on the standard monitor of the sRGB standard. To do.

  Therefore, in order to cope with the wide color gamut, the sYCC standard having a color space wider than sRGB has been standardized in the industry. The sYCC standard is ITU-R BT. 601 (International standard for RGB to YCC conversion matrix defined for HDTV) is used to derive the luminance / chrominance separation space. As the color space, the sYCC standard has a wider color gamut. Colors outside the sRGB standard can also be expressed.

On the other hand, the NTSC (National Television System Committee) standard adopted as a color television broadcasting system has a wider bandwidth than the sRGB standard.
Therefore, in order to realize the color gamut of the sYCC standard, it is necessary to be equivalent to the NTSC color gamut or exceed the NTSC color gamut on the display.

In general, in a transmissive color liquid crystal display device, for example, a blue filter CFB ₀ (465 nm), a green filter CFG ₀ (525 nm), and a red filter CFR ₀ (615 nm) having spectral characteristics (spectral characteristics) as shown in FIG. A color filter using the three primary color filters is provided for each pixel of the color liquid crystal display panel.
The general red color filter CFR ₀ is formed to have a predetermined transmittance in the wavelength transmission band of the blue filter CFB _{0 in} order to compensate for the low visibility of human blue light.

With respect to a color filter having such spectral characteristics, white light emitted from a three-wavelength type CCFL used as a light source of a backlight device of a color liquid crystal display device exhibits a spectrum as shown in FIG. In other words, light of different intensities is included.
Therefore, the color reproduced by the combination of the backlight device using such a three-wavelength CCFL as the light source and the color liquid crystal display panel having the color filter as described above is mixed, resulting in a very high color purity. There is a problem that is bad.

FIG. 19 shows a combination of the spectral characteristics of the color filter shown in FIG. 17 and the CCFL spectrum shown in FIG.
As shown in FIG. 18, there is a sub-peak in the vicinity of 490 nm in the spectrum of normal use (normal CCFL).
As shown in FIG. 19, since the sub-peaks are covered with the transmission band of the blue filter and the green filter, color mixture of blue and green occurs, resulting in poor color purity.

  Further, FIG. 20 shows a color reproduction range of a color liquid crystal display device including a backlight device using the above-described three-wavelength light emitting CCFL as a light source. FIG. 20 is an xy chromaticity diagram of the XYZ color system defined by the International Commission on Illumination (CIE).

The color reproduction range of a color liquid crystal display device equipped with a backlight device using CCFL as a light source is almost the same as that of a conventional CRT (cathode ray tube), and as shown in FIG. 20, is almost the same as the color reproduction range of the sRGB standard. It has become the size of.
However, the vertices above the triangular color reproduction range, that is, the chromaticity point of the green region is to the left of the chromaticity point of the green region of the sRGB standard (the x coordinate is small). The color reproduction range of the sRGB standard is partially not covered in the right side area. This is considered to be due to the above-described color mixture of blue and green.
In addition, the color reproduction range of a color liquid crystal display device equipped with a backlight device using CCFL as a light source is a color defined by the NTSC (National Television System Committee) standard adopted as a color television broadcasting system. The range is narrower than the reproduction range (not shown).
Therefore, there is a problem that it cannot be said that the present television broadcasting can be sufficiently handled.

JP 2001-22285 A

  Therefore, in CCFL, as described above, it has been studied to expand the color gamut in the same manner as the NTSC standard space wider than sRGB.

Previously, the present applicant has proposed to construct a wide color gamut CCFL (cold cathode fluorescent tube) capable of expressing a wide color gamut, for example, by partially improving the phosphor.
By using this wide color gamut CCFL, the representable color gamut can be made wider than that of the conventional CCFL.

However, when this wide color gamut CCFL is combined with a conventionally used color filter, the sRGB area is not completely covered.
In particular, the green area was significantly off.

  Therefore, in order to cover the conventional sRGB space while making use of the color gamut expansion of the wide color gamut CCFL, it is necessary to combine color filters that are compatible with the wide color gamut CCFL of the light source.

In order to correspond to the color gamut of the sYCC standard described above, it is required to have a wider color reproduction range than the color gamut of the sRGB standard.
However, as long as it is basically composed of only the three primary color (R, G, B) color filters, there is a limit to the improvement in color reproducibility.

  In order to solve the above problems, the present invention provides a color liquid crystal display device capable of displaying a wide color gamut.

  The color liquid crystal display device of the present invention comprises a transmissive color liquid crystal display panel provided with a color filter and a backlight light source for liquid crystal display that illuminates the color liquid crystal display panel from the back side. In the xy chromaticity diagram of the colorimeter, a fluorescent tube having a chromaticity point of emitted white light in the vicinity of (x, y) = (0.275, 0.275) is provided, and the color filter includes red light, The filter comprises three primary color filters that selectively transmit green light and blue light with wavelengths, and at least one complementary color filter selected from cyan, magenta, and yellow.

According to the above-described configuration of the color liquid crystal display device of the present invention, in the xy chromaticity diagram of the XYZ colorimeter, the chromaticity point of the emitted white light is (x, y) = (0.275, 0.275). Since the backlight light source is configured to include the fluorescent tube in the vicinity of, the color gamut of the color reproduction range of the color liquid crystal display device can be made wider than when a conventional fluorescent tube is used.
The color filter is composed of three primary color filters that selectively transmit red light, green light, and blue light, and at least one complementary color filter selected from cyan, magenta, and yellow. Even in a color gamut that is difficult to cover with a filter (cyan, magenta, and yellow complementary color system), the color reproduction range can be expanded.

According to the present invention described above, the color reproduction range can be expanded even in the complementary color system regions of cyan, magenta, and yellow, which are difficult to cover with the three primary color filters. Can be expanded further than before, and a wide color gamut can be displayed.
As a result, the emerald sea, the deep red of wine red, the deep green of the sprouting trees, and the like can be displayed naturally closer to the original color.
For example, it is possible to completely cover the sRGB standard area or to correspond to the sYCC standard area.

  First, an outline of the present invention will be described prior to description of specific embodiments of the present invention.

Here, using the color chart of 768 colors called Munsell color cascade (also called Pointer's Color), which follows the Munsell color system, a color display system devised by American painter Munsell (AHMunsell 1858-1918), Represents the color that exists in the.
The Munsell color cascade is a color chart in which 16 gradations and 48 hues (16 × 48 = 768) are created using the color of the color material with the highest saturation as the color chart. The Munsell color cascade is a display system in which pigments are arranged to correspond to one point in a three-dimensional coordinate axis according to three attributes of color, that is, hue, brightness, and saturation.

A color chart of this color cascade is plotted in FIG. 14 as ♦ in the xy chromaticity diagram of the XYZ color system.
Further, FIG. 15 shows the color chart of this color cascade and the color reproduction range of the conventional sRGB standard superimposed. Calculation from FIG. 15 shows that the sRGB standard covers only about 55% of the color cascade.
That is, it can be seen that a CRT (cathode ray tube) used in the past can express only 55% of the world's colors.

By the way, as described above, when a color liquid crystal display device is configured by combining a wide color gamut CCFL and a conventionally used color filter, the sRGB region is not completely covered.
Here, the spectrum of the wide color gamut CCFL and the spectral characteristics of the color filters (CFR ₀ , CFG ₀ , CFB ₀ ) conventionally used are superimposed and shown in FIG.

As shown in FIG. 16, in the wide color gamut CCFL, there is a broad sub-peak from 500 nm to 550 nm instead of the sub-peak near 490 nm that was normally in the CCFL. Since the blue filter CFB ₀ is applied to this sub-peak, green leakage occurs in the blue color gamut, and the blue color gamut does not widen.
Further, since the green filter CFG ₀ covers the blue spectrum of the wide color gamut CCFL, blue leakage occurs in the green color gamut and the green color gamut is shifted.
Further, since the red filter CFR ₀ has absorption in a short wavelength region (wavelength 400 nm to 450 nm), blue leakage occurs in the red color gamut, and the red color gamut is narrowed due to color mixing.

Therefore, in the color liquid crystal display device of the present invention, not only a fluorescent tube improved for a wider color gamut than a conventional fluorescent tube such as a CCFL (cold cathode fluorescent tube) is used as a backlight light source, but also this fluorescent tube is used. In contrast, an optimum color filter is combined with the fluorescent tube.
Thereby, it is possible to widen the color gamut of the color liquid crystal display device.
It is also possible to completely cover the sRGB standard area, which was difficult in color reproduction with the conventional CCFL.

  As a fluorescent tube, a fluorescent tube (a cold cathode fluorescent tube or a hot cathode fluorescent tube) having a wide emission color gamut is obtained by changing the type or amount of the phosphor used in the phosphor layer from a conventional fluorescent tube. ) Is used. Thereby, the color reproduction range of the fluorescent tube becomes wider than that of the conventional fluorescent tube.

  Specifically, a fluorescent tube having a wide emission color gamut has an xy chromaticity diagram of an XYZ colorimeter where the chromaticity point of emitted white light is (x, y) = (0.275, 0. 275).

  The color filter is configured by adding one to three colors of complementary color filters to the three primary color filters.

Examples of the material constituting the color filter of each color include the following pigments.
Examples of R (red) pigments include monoazo pigments, disazo pigments, xanthene pigments, and anthraquinone pigments.
Examples of G (green) pigments include triphenylmethane, phthalocyanine, nitroso, and indamine pigments.
As the B (blue) pigment, pigments such as triphenylmethane, phthalocyanine, and triarylmethane are used.
In order to determine the basic color tone based on the above three main pigment colors (R, G, B) and further adjust to the target chromaticity, a sub-pigment is added.
As an auxiliary pigment for R pigment and G pigment, a monoazo pigment, a disazo pigment, an anthraquinone pigment, an isoindolinone pigment or the like is used as a Y (yellow) pigment. As the sub-pigment for the B pigment, a xanthene-based, dioxazine-based, quinacridone-based, indigoid-based pigment or the like is used as a V (purple) pigment.
It is possible to control the spectral characteristics of the color filter by adjusting the mixing ratio of the main pigment and the sub-pigment not only for the three primary color filters but also for the complementary color filters (cyan, magenta, yellow). It is.

  More preferably, each color filter is configured to have the following spectral characteristics.

(1) Blue color filter (blue filter) CFB
The peak wavelength of the blue filter CFB that selectively transmits blue light is set to 420 nm or more and 455 nm or less.
Further, the half width of the spectral characteristic peak is preferably 110 nm or less, more preferably about 80 nm to 100 nm.

By adopting such spectral characteristics, the peak wavelength is on the short wavelength side of about 10 nm to 45 nm compared to the blue filter (peak wavelength of 465 nm) that has been generally used in the past, thus reducing color mixing with the green filter. And the blue color gamut can be expanded.
It is also possible to cover the sRGB standard area by setting the blue chromaticity point in the color reproduction range of the color liquid crystal display device within the diagonal area described above.

(2) Green color filter (green filter) CFG
The peak wavelength of the green filter CFG that selectively transmits green light with a wavelength is set to 530 nm or more and 550 nm or less.
Further, the half width of the spectral characteristic peak is preferably 120 nm or less, more preferably about 90 nm to 110 nm.

By adopting such spectral characteristics, the peak wavelength is on the long wavelength side of about 5 nm to 25 nm compared to the conventionally used green filter (peak wavelength: 525 nm), thus reducing color mixing with the blue filter. can do.
It is also possible to cover the sRGB standard area by moving the green chromaticity point in the color reproduction range of the color liquid crystal display device to the longer wavelength side and within the diagonal area described above.

(3) Red color filter (red filter) CFR
The rising wavelength of the red filter CFR that selectively transmits red light is set to be 570 nm or in the vicinity of 570 nm.
Further, the transmittance at a wavelength of 400 nm to 500 nm is set to almost zero.
The peak wavelength is preferably 600 nm or more.

By setting such spectral characteristics, it is possible to reduce color mixing with the blue filter.
It is also possible to cover the region of the sRGB standard by setting the red chromaticity point in the color reproduction range of the color liquid crystal display device to a more outer position.

(4) Cyan filter (cyan filter) CFC
The peak wavelength of the cyan filter is preferably 480 nm ± 10% (432 nm to 428 nm). The half width of the spectral characteristic peak is preferably 80 nm ± 10% (72 nm to 88 nm).

  By setting such spectral characteristics, it is possible to sufficiently widen the cyan region of the color reproduction range of the color liquid crystal display device.

(5) Yellow (yellow) filter (yellow filter) CFY
The peak wavelength of the yellow filter is preferably 575 nm ± 10% (517.5 nm to 632.5 nm). The half width of the spectral characteristic peak is preferably 80 nm ± 10% (72 nm to 88 nm).

  By setting such spectral characteristics, it is possible to sufficiently widen the yellow area of the color reproduction range of the color liquid crystal display device.

  A magenta filter (magenta filter) CFM is also considered to have preferable spectral characteristics, but the description thereof is omitted here.

Of the three primary color (blue, green, red) filters and the complementary color (cyan, yellow) filters, if at least one of the above-mentioned spectral characteristics is used, the conventional color filter is used. In comparison, the color reproduction range of the color liquid crystal display device can be expanded, and the NTSC ratio can also be improved.
Of course, the color reproduction range of the color liquid crystal display device can be sufficiently expanded by setting the above-mentioned spectral characteristics for the three primary color filters and the complementary color filters. It is possible to cover the sRGB standard area at the chromaticity point of each color.

Subsequently, specific embodiments of the present invention will be described.
As an embodiment of the present invention, a schematic configuration diagram (disassembled perspective view) of a backlight type color liquid crystal display device is shown in FIG.
The color liquid crystal display device 100 includes a transmissive color liquid crystal panel 10 and a backlight unit 40 provided on the back side of the color liquid crystal display panel 10.

In the transmissive color liquid crystal display panel 10, two transparent substrates (TFT substrate 11 and counter electrode substrate 12) made of glass or the like are arranged to face each other, and, for example, twisted nematic (TN) liquid crystal is provided in the gap. The liquid crystal layer 13 encapsulating the liquid crystal layer 13 is provided. A thin film transistor (TFT) 16 as a switching element and a pixel electrode 17 are formed on the TFT substrate 11 in a matrix.
The thin film transistor 16 is sequentially selected by the scanning line 15 and writes the video signal supplied from the signal line 14 to the corresponding pixel electrode 17.
The counter electrode substrate 12 has a counter electrode 18 and a color filter 19 formed on the inner surface thereof.
The color filter 19 is divided into segments corresponding to the respective pixels.

  In this color liquid crystal display device 100, the transmissive color liquid crystal display panel 10 having such a configuration is sandwiched between two polarizing plates 31 and 32, and the backlight unit 40 irradiates white light from the back side in an active state. By driving in a matrix system, a desired full color image can be displayed.

The backlight unit 40 illuminates the color liquid crystal display panel 10 from the back side. As shown in FIG. 1, the backlight unit 40 includes a light source, and a backlight device 20 that emits white light from a light irradiation surface 20 a by mixing white light emitted from the light source, and light of the backlight device 20. It is comprised from the diffusion plate 41 laminated | stacked on the output surface 20a.
The diffusing plate 41 diffuses white light emitted from the light emitting surface 20a to make the luminance uniform in surface emission.

The backlight device 20 includes a large number of CCFLs (cold cathode fluorescent tubes) 21 arranged substantially in parallel.
In this color liquid crystal display device 100, the longitudinal direction of the CCFL 21 and the stripe direction of the color filter 19 are arranged so as to be substantially orthogonal to each other.

  The color liquid crystal display device of the present invention is not limited to such an arrangement of CCFLs. For example, the longitudinal direction of the CCFL and the direction of the color filter stripe may be arranged substantially parallel to each other. For the specific arrangement of the CCFL 21 in the backlight device 20, a conventionally known configuration such as the configuration described in Patent Document 1 can be applied.

The color liquid crystal display device 100 is driven by, for example, a drive circuit 200 as shown in FIG.
The driving circuit 200 is supplied from the outside, the color liquid crystal display panel 10, a power supply unit 110 that supplies driving power to the backlight device 20, an X driver circuit 120 and a Y driver circuit 130 that drive the color liquid crystal display panel 10. An RGB process processing unit 150 that receives a video signal or a video signal received by a receiving unit (not shown) included in the color liquid crystal display device 100 and processed by the video signal processing unit, via the input terminal 140, and the RGB process A video memory 160 and a control unit 170 connected to the processing unit 150, a backlight drive control unit 180 that drives the backlight device 20 of the backlight unit 40, and the like are provided.

  In this drive circuit 200, the video signal input via the input terminal 140 is subjected to signal processing such as chroma processing by the RGB process processing unit 150, and is suitable for driving the color liquid crystal display panel 10 from the composite signal. It is converted into an RGB separate signal, supplied to the controller 170, and supplied to the X driver 120 via the image memory 160.

  Further, the control unit 170 controls the X driver circuit 120 and the Y driver circuit 130 at a predetermined timing according to the RGB separate signal, and uses the RGB separate signal supplied to the X driver circuit 120 via the image memory 160. By driving the color liquid crystal display panel 10, an image corresponding to the RGB separate signal is displayed.

  The backlight control driving unit 180 generates a pulse width modulation (PWM) signal from the voltage supplied from the power supply 110 and drives the light source (CCFL) of the backlight device 20.

  The user interface 300 selects a channel received by a receiving unit (not shown), adjusts an audio output amount to be output by an audio output unit (not shown), and emits white light from the backlight device 20 that illuminates the color liquid crystal display panel 10. This is an interface for executing brightness adjustment, white balance adjustment, and the like.

  Although not shown, the color liquid crystal display device 100 includes a receiving unit such as an analog tuner and a digital tuner that receives terrestrial and satellite waves, a video signal processing unit that processes video signals and audio signals received by the receiving unit, An audio signal processing unit, an audio signal output unit such as a speaker that outputs an audio signal processed by the audio signal processing unit, and the like may be provided.

  In the color liquid crystal display device 100 of the present embodiment, in particular, the CCFL having a wider color gamut than the conventional CCFL, that is, the aforementioned wide color gamut CCFL is used as the CCFL (cold cathode fluorescent tube) 21 of the light source of the backlight device 20. At the same time, the color filter 19 is adapted to the wide color gamut CCFL as a configuration different from the conventional color filter.

Here, FIG. 3 shows the wavelength distribution (spectrum) of the emission color of one form of the wide color gamut CCFL used in the present embodiment.
Note that the spectrum shown in FIG. 3 is the same as the spectrum of the wide color gamut CCFL shown in FIG.

  Since this wide color gamut CCFL has a spectrum as shown in FIG. 3, in the xy chromaticity diagram of the XYZ colorimeter, the chromaticity point of the emitted white light is (x, y) = (0.275, 0.275).

The wide color gamut CCFL having the above-described luminescent color can be produced, for example, as follows.
For example, YVO ₄ : Eu is used as the red light-emitting phosphor, and BaMgAl ₁₀ O ₁₇ : Eu, Mn (BAM: Eu, Mn) is used as the green light-emitting phosphor. For example, BaMgAl is used as the blue light-emitting phosphor. _{Using 10} O ₁₇ : Eu (BAM: Eu), a phosphor slurry containing a phosphor particle mixture obtained by mixing these phosphor particles is prepared, and is made to flow on the inner surface of the glass tube to form a phosphor layer. A CCFL (cold cathode fluorescent tube) is manufactured using the glass tube on which the phosphor layer is formed.
Then, the mixing ratio of each phosphor particle is adjusted so that the emission chromaticity of the manufactured cold cathode fluorescent tube is, for example, (0.275, 0.275) in the chromaticity coordinates of the emission color. For example, the mixing ratio may be 25 to 75% by weight of red light emitting phosphor particles, 20 to 60% by weight of green light emitting phosphor particles, and 5 to 40% by weight of blue light emitting phosphor particles.
With such a configuration, a wide color gamut CCFL is obtained.
A detailed method for producing the wide color gamut CCFL is described in, for example, Japanese Patent Application No. 2004-147887 filed earlier by the present applicant.

  In the color liquid crystal display device 100 of the present embodiment, the color filter 19 included in the color liquid crystal display panel 10 includes, for example, three primary colors of a red filter CFR, a green filter CFG (peak 535 nm), and a blue filter CFB (peak 445 nm). A color filter (each having spectral characteristics shown in FIG. 4) and a complementary color filter of two colors, a cyan filter CFC and a yellow filter CFY, are used. Hereinafter, these five color filters are referred to as a color filter 19A.

For example, as shown in FIG. 5, the five color filters are composed of five segments in a stripe arrangement in which a red filter CFR, a yellow filter CFY, a green filter CFG, a cyan filter CFC, and a blue filter CFB are arranged in this order. To do.
Then, the width of each of the five segments is made narrower than the width of each of the three segments in the configuration of the color liquid crystal display panel having the color filters of the three primary colors, and the total of the widths of the five segments. Is approximately equal to the sum of the widths of the three segments in the configuration of a normal color liquid crystal display panel. Thereby, the area of a pixel can be made equivalent to the structure of a normal color liquid crystal display panel.
Also, the TFT (thin film transistor) of the TFT substrate 11 has a width narrower than that of a normal configuration corresponding to the segment.

  In addition to the stripe arrangement as shown in FIG. 5, the arrangement pattern of the color filter includes a delta arrangement, a square arrangement, etc. (not shown).

  Further, the spectrum of the wide color gamut CCFL shown in FIG. 3, the spectral characteristics of the three primary color filters CFR, CFG, and CFB shown in FIG. 4, and the spectral characteristics of the conventionally used color filter shown in FIG. Are shown in FIG.

As indicated by an arrow ΔG in FIG. 6, the transmission wavelength band of the green filter CFG of the color filter 19A is shifted to a longer wavelength side by about 10 nm than the conventionally used green filter CFG ₀ .
As a result, the blue wavelength band emitted by the wide color gamut CCFL is prevented from becoming the transmission wavelength band of the green filter CFG.
Further, since the wavelength band of the green light emitted from the color liquid crystal display device 100 is substantially determined by the transmission wavelength band of the green filter CFG, the transmission wavelength band of the green filter CFG is shifted to the longer wavelength side, thereby causing the green light It is also possible to prevent the wavelength band of 1 from being applied to the transmission wavelength band of the blue filter CFB.

As shown by the arrow ΔB in Figure 6, the transmission wavelength band of the blue filter CFB of the color filter 19A, rather than the blue filter CFB ₀ which is conventionally used, it is shifted to 20nm about the short wavelength side.
As a result, the green wavelength band emitted by the wide color gamut CCFL is prevented from becoming the transmission wavelength band of the blue filter CFB.
Further, since the wavelength band of blue light emitted from the color liquid crystal display device 100 is substantially determined by the transmission wavelength band of the blue filter CFB, the transmission wavelength band of the blue filter CFB is shifted to the short wavelength side, so that the blue light It is also possible to prevent the wavelength band of 1 from being applied to the transmission wavelength band of the green filter CFG.

  That is, by combining the color filter 19A with the wide color gamut CCFL, it is possible to prevent the color mixture of blue and green.

Further, as indicated by an arrow ΔR in FIG. 6, the red filter CFR of the color filter 19A has a transmittance at a wavelength of 400 nm to 500 nm that is lower than that of the conventionally used red filter CFR ₀ , and the transmittance is almost the same. It is zero.
As a result, the light having the same wavelength band as the transmission wavelength band of the blue filter CFB out of the light incident on the red filter CFR is not transmitted through the red filter CFR, so the color purity of the red light transmitted through the red filter CFR Becomes higher.

  In the present embodiment, the primary color filters CFR, CFG, and CFB have the spectral characteristics shown in FIGS. 4 and 6, for example, as follows. CFB is produced.

(1) Blue filter CFB
The amount of V (purple) pigment added to the B (blue) pigment was adjusted so that the peak wavelength shift amount with respect to the blue filter CFB ₀ used conventionally was about 20 nm. Eventually, the composition of the pigment was adjusted to 5 to 10% by weight% of the entire color resist. The remaining components of the color resist are an organic solvent, a dispersant, a binder resin, and the like.
Here, B-15 was used as the material for the B (blue) pigment, and V-23 was used as the material for the V (purple) pigment.

(2) Green filter CFG
The amount of Y (yellow) pigment added to the G (green) pigment was adjusted so that the peak wavelength shift amount with respect to the conventionally used green filter CFG0 was about 10 nm. Finally, the composition of the pigment was adjusted to 5 to 10% by weight.
Here, G-36 was used as the material for the G (green) pigment, and Y-150 was used as the material for the Y (yellow) pigment.

(3) Red filter CFR
In order to eliminate absorption on the short wavelength side, the amount of Y (yellow) pigment added to the R (red) pigment was adjusted. Finally, the composition of the pigment was adjusted to 5 to 10% by weight.
Here, R-254 was used as the material for the R (red) pigment, and Y-139 was used as the material for the Y (yellow) pigment.

  The material of each pigment such as B-15 and V-23 is listed in a general pigment list, and for example, those manufactured by Dainichi Seika Co., Ltd. are commercially available.

  As the two-color complementary color filters CFC and CFY, conventionally used cyan filters and yellow filters can be used.

Here, a color liquid crystal display device was actually fabricated and its characteristics were examined.
As shown schematically in FIG. 7, a color luminance meter 300 was placed above the color filter 19 of the color liquid crystal display device 100, and spectral characteristics were measured.
Then, the coverage ratio of the color cascade was calculated by plotting the spectral characteristics on the XYZ color system chromaticity diagram and examining the number of color cascades of the Munsell color system outside the color reproduction range. Moreover, NTSC ratio was calculated | required from this XYZ color system chromaticity diagram.

  And when the backlight light source is a conventional CCFL (usually CCFL) and the color filter is a conventional one (usually CF), and the backlight light source is a wide color gamut CCFL and the color filter is conventionally used. A combination of a wide color gamut CCFL and the same three primary color filter (improved CF) as the three primary color filters used in the present embodiment, and a wide color gamut CCFL and this For the case where the five-color filter (multicolor CF) according to the embodiment was combined, each color liquid crystal display device was manufactured, and the spectral characteristics were measured by the measurement method described above.

First, a characteristic distribution (xy chromaticity diagram) when a conventional CCFL (normal CCFL) is combined with a conventionally used color filter (normal CF) (the wavelength distribution of the CCFL and the color filter is as shown in FIG. 19). ) Is shown in FIG.
In this case, the color cascade coverage was 65% and the NTSC ratio was 72%.

Next, FIG. 9 shows a characteristic distribution (xy chromaticity diagram) when the wide color gamut CCFL and the normal CF are combined (the wavelength distribution of the CCFL and the color filter is as shown in FIG. 16).
In this case, the color cascade coverage was 73% and the NTSC ratio was 90%.

Next, FIG. 11 shows a characteristic distribution (xy chromaticity diagram) when the wide color gamut CCFL and the improved CF are combined (the wavelength distribution of the CCFL and the color filter is as shown in FIG. 10).
In this case, the color cascade coverage was 82% and the NTSC ratio was 100%.
In this case, the NTSC ratio is very wide, but only 80% of the actual color (color cascade) coverage can be reproduced. In particular, as shown in FIG. 11, color reproduction is expected to be poor in the upper left Cyan region and the upper right Yellow region.

Next, FIG. 13 shows the characteristic distribution when the wide color gamut CCFL and the five-color filter (multicolor CF) of this embodiment are combined (the wavelength distribution of the CCFL and the color filter is as shown in FIG. 12). Shown in
In this case, the color cascade coverage was 95% and the NTSC ratio was 110%.
The cover ratio is almost satisfactory and is in a range where most colors can be reproduced.

  In addition, the number of color cascades outside the color gamut of the color liquid crystal display device (number of cyan cyan, yellow yellow, and magenta magenta color regions and their totals), color cascade coverage, and NTSC ratio are summarized. Table 1 shows.

From Table 1, it can be seen that the color gamut is widened and the color cascade coverage is improved by employing a configuration in which a complementary color filter is added (multicolor CF).
In addition, the sRGB standard area can be covered with the chromaticity points of the respective primary colors, and the color cascade can be nearly 100% covered.
Thus, as an effect, the emerald sea, the wine red crimson, the deep green of the sprout trees, etc. can be displayed closer to the original color and naturally.

  According to the configuration of the color liquid crystal display device 100 of the present embodiment described above, the CCFL 21 composed of the wide color gamut CCFL whose spectrum is shown in FIG. 3 is used as the light source of the backlight device 20 and corresponds to the wide color gamut CCFL. By configuring the color liquid crystal display device 100 using the color filter 19 composed of the three primary color filters CFR, CFG, and CFB with improved spectral characteristics and the complementary color filters CFC and CFY, a wide color gamut CCFL is obtained. And compared with the case where the color filter used conventionally is used, the color mixture of each color can be suppressed and a color reproduction range can be widened.

This also makes it possible to completely cover the sRGB standard area.
It is also possible to increase the NTSC ratio to 100% or higher, or to correspond to the sYCC standard area.

In the above-described embodiment, the multicolor color filter including the five color filters is configured by using the two complementary color filters CFC and CFY. However, the present invention is applied to other configurations. Can do.
In the present invention, any one or more of the three colors (cyan, yellow, magenta) is used as the complementary color filter, and this complementary color filter and the three primary color filters are combined to produce a multicolor (four colors). (6 colors) color filter may be configured.

  In the above-described embodiment, the improved CF having improved spectral characteristics corresponding to the spectrum of the wide color gamut CCFL is used as the color filter for the three primary colors. However, in the present invention, the color filter for the normal three primary colors is used. A multicolor color filter may be configured by combining complementary color filters. Even in such a configuration, a wide color gamut can be displayed by the effect of the wide color gamut CCFL and the effect of the complementary color filter.

  In the above-described embodiment, a wide color gamut CCFL (cold cathode fluorescent tube) is used as a backlight light source. However, in the present invention, a hot cathode fluorescent tube having a phosphor layer similar to the wide color gamut CCFL is used. You may use for a backlight light source. In this case as well, the color gamut of the backlight source can be expanded by selecting the configuration of the phosphor layer.

In addition, the present invention is not limited to a configuration in which illumination is performed directly from a fluorescent tube in the backlight device, but can also be applied to a configuration in which illumination is performed indirectly from a fluorescent tube via a light guide plate.
A conventionally well-known configuration can be applied to the arrangement of the fluorescent tubes in the backlight device.

  The present invention is not limited to the above-described embodiment, and various other configurations can be taken without departing from the gist of the present invention.

1 is a schematic configuration diagram (disassembled perspective view) of a color liquid crystal display device according to an embodiment of the present invention. It is a figure which shows the structure of the drive circuit of the color liquid crystal display device of FIG. It is a figure which shows the wavelength distribution (spectrum) of the luminescent color of one form of the wide color gamut CCFL used for the color liquid crystal display device of FIG. It is a figure which shows the spectral characteristic of the color filter of three primary colors used for the color liquid crystal display device of FIG. It is a figure which shows the arrangement pattern of the color filter of the color liquid crystal display device of FIG. FIG. 18 is a diagram in which the spectrum of FIG. 3, the spectral characteristics of FIG. 4, and the spectral characteristics of FIG. 17 are superimposed. It is the schematic which shows arrangement | positioning of the color luminance meter in the case of the measurement of a spectral characteristic. It is characteristic distribution (xy chromaticity diagram) at the time of combining normal CCFL and normal CF. It is a characteristic distribution (xy chromaticity diagram) when a wide color gamut CCFL and a normal CF are combined. It is wavelength distribution of CCFL and a color filter at the time of combining wide color gamut CCFL and improved CF. It is a characteristic distribution (xy chromaticity diagram) in the case of combining the wide color gamut CCFL and the improved CF. This is a wavelength distribution of CCFL and color filter when wide color gamut CCFL and multicolor CF are combined. It is a characteristic distribution (xy chromaticity diagram) in the case of combining a wide color gamut CCFL and a multicolor CF. It is the figure which plotted the color chart of a color cascade in the xy chromaticity diagram of an XYZ color system. It is a figure which shows the color chart of a color cascade and the color reproduction range of the conventional sRGB standard in an overlapping manner. It is the figure which piled up the spectrum of the wide color gamut CCFL, and the spectral characteristic of the color filter conventionally used. It is a figure which shows the spectral characteristic of the color filter of a transmissive | pervious color liquid crystal display device. It is a spectrum of white light emitted from a three-wavelength type CCFL. FIG. 19 is a diagram showing a combination of the spectral characteristics of the color filter shown in FIG. 17 and the CCFL spectrum shown in FIG. 18. FIG. 4 is an xy chromaticity diagram of an XYZ color system showing a color reproduction range of a color liquid crystal display device including a backlight device using a three-wavelength light emitting CCFL as a light source.

Explanation of symbols

  10 color liquid crystal display panel, 19 color filter, 20 backlight device, 21 CCFL (cold cathode fluorescent tube), 100 color liquid crystal display device, CFR red filter, CFG green filter, CFB blue filter, CFC cyan filter, CFY yellow filter

Claims (5)

A transmissive color liquid crystal display panel with a color filter;
A backlight source for liquid crystal display that illuminates the color liquid crystal display panel from the back side,
The backlight source includes a fluorescent tube having a chromaticity point of white light to be emitted in the vicinity of (x, y) = (0.275, 0.275) in the xy chromaticity diagram of the XYZ colorimeter,
The color filter is composed of a three-primary color filter that selectively transmits wavelengths of red light, green light, and blue light, and at least one complementary color filter selected from cyan, magenta, and yellow. Display device.   2. The color liquid crystal display device according to claim 1, wherein the three primary color filters have a peak wavelength of 420 nm or more and 455 nm or less of at least a blue filter that selectively transmits blue light.   2. The color liquid crystal display device according to claim 1, wherein the three primary color filters have a peak wavelength of at least 530 nm and not more than 550 nm of a green filter that selectively transmits at least green light.   The three primary color filters are characterized in that at least a red filter that selectively transmits red light with a wavelength has a rising wavelength in the vicinity of 570 nm or 570 nm, and has a transmittance of almost zero at a wavelength of 400 nm to 500 nm. Item 2. A color liquid crystal display device according to item 1. The peak wavelength of the green filter that selectively transmits green light is 530 nm to 550 nm, and the red filter that selectively transmits red light has a rising wavelength in the vicinity of 570 nm or 570 nm and transmits at a wavelength of 400 nm to 500 nm. The color liquid crystal display device according to claim 2, wherein the rate is substantially zero.

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