JP2009244617A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reproduce a color of deep green in a liquid crystal display device. <P>SOLUTION: A mixed pigment of a zinc phthalocyanine green pigment (e.g. PG58 green pigment) and a PY150 yellow pigment is used as a pigment of a green color filter. When it is defined that an amount of the zinc phthalocyanine green pigment is G and an amount of the Y150 yellow pigment is Y, G/(G+Y) is set to 55 to 90%. A light source obtained by combining a blue LED with a red phosphor and a green phosphor is used as a light source of a backlight. In the liquid crystal display device having such a configuration, a y-value of green on choromaticity coordinates of a CIE can be set to 0.71 and more. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device excellent in image color reproducibility.

  A liquid crystal display panel used in a liquid crystal display device has a TFT substrate in which pixels formed with pixel electrodes, thin film transistors (TFTs) and the like are formed in a matrix, and a counter substrate on which color filters are formed. The liquid crystal is sandwiched between the TFT substrate and the counter substrate. Since a liquid crystal display panel does not emit light by itself, a backlight is necessary.

  As the backlight, white light is generally used. In a liquid crystal display device, an image is formed by controlling transmission of white light from a backlight by a liquid crystal layer for each pixel. In order to form a color image, color filters such as red, green, and blue are formed on the opposite substrate corresponding to the pixels, and the color image is formed by controlling the transmission of light from the backlight for each pixel. ing.

  Therefore, the color reproducibility of the formed image is affected by the characteristics of the color filter formed on the counter substrate and the characteristics of the light source of the backlight. “Patent Document 1” describes a material for a color filter used in a liquid crystal display device. In particular, “Patent Document 1” uses 0.55 ≦ y ≦ 0 in CIE chromaticity coordinates when color measurement is performed using an F10 light source by using partially brominated zinc phthalocyanine as a pigment of a green color filter. There is a description that the chromaticity range of 71 can be displayed.

JP 2004-70342 A

  “Patent Document 1” describes a green color filter capable of displaying a chromaticity range of 0.55 ≦ y ≦ 0.71 when measured using a light source of F10. However, in the configuration described in “Patent Document 1”, there is no description of a configuration in which the y value of the green degree exceeds 0.71. Here, F10 is a standard light source for measuring the characteristics of the color filter.

  However, in an actual liquid crystal display device, the chromaticity range that can be displayed is not determined solely by the color filter. The spectrum of the backlight plays an important role in the chromaticity of the image formed by the liquid crystal display device. That is, “Patent Document 1” does not describe a configuration for realizing a deep green image with excellent color purity in an actual liquid crystal display device.

  An object of the present invention is to obtain a configuration in which a color reproduction range of an image displayed by a liquid crystal display device is widened by a configuration of a green color filter and a backlight.

  The present invention solves the above-described problems, and specific means are as follows.

  (1) A liquid crystal display panel in which a liquid crystal layer is sandwiched between a TFT substrate on which a TFT and a pixel electrode are formed, a counter substrate disposed opposite to the TFT substrate, and a back surface of the liquid crystal display panel. The TFT substrate or the counter substrate includes a color filter, the color filter includes a red filter, a blue filter, and a green filter, and the green filter includes: A liquid crystal display device comprising a zinc phthalocyanine green pigment, wherein the backlight includes a light source in which a blue LED, a red phosphor, and a green phosphor are combined.

  (2) The liquid crystal display device according to (1), wherein the green CIE chromaticity value emitted from the liquid crystal display device has a y value of 0.71 or more.

  (3) The liquid crystal display device according to (1), wherein the green CIE chromaticity value emitted from the liquid crystal display device has a y value larger than 0.71.

  (4) The green color filter includes the zinc phthalocyanine green pigment and a yellow pigment, and when the amount of the zinc phthalocyanine green pigment is G and the amount of the yellow pigment is Y, 0.55 ≦ G / ( G + Y) ≦ 0.90, The liquid crystal display device according to any one of (1) to (3).

  (5) The liquid crystal display device according to (4), wherein the yellow pigment is PY150.

  (6) The liquid crystal display device according to (4), wherein the yellow pigment is PY138 or PY139.

  (7) The liquid crystal display device according to any one of (1) to (6), wherein the green color filter is formed using a photosensitive dispersion containing the zinc phthalocyanine green pigment.

  (8) The liquid crystal display device according to any one of (1) to (7), wherein the zinc phthalocyanine green pigment of the green color filter is a partially brominated zinc phthalocyanine green pigment.

  (9) The liquid crystal display device according to (8), wherein the partially brominated zinc phthalocyanine green pigment is PG58.

  According to the present invention, a green color filter containing a zinc phthalocyanine green pigment is used, and a combination of a blue LED, a red phosphor and a green phosphor is used as a light source for a backlight, so that deep green is realized as a liquid crystal display device. I can do it.

  Further, by using the configuration of the present invention, it is possible to widen the range in which full color reproduction is possible.

The detailed contents of the present invention will be disclosed according to the embodiments.

  FIG. 1 is a schematic cross-sectional view of a liquid crystal display device to which the present invention is applied. In FIG. 1, a TFT 12, a pixel electrode 11, a signal line 13 and the like are formed on a TFT substrate 10. In order to form the TFT 12, many layers such as a semiconductor film, a gate electrode, a drain electrode, a gate insulating film, an interlayer insulating film, a passivation film, and a planarizing film are necessary, but are omitted in FIG.

  On the TFT substrate 10, scanning lines for supplying a scanning signal to the gate electrode of the TFT 12 extend in the horizontal direction of the screen, for example, and are arranged in the vertical direction of the screen. In addition, video signal lines for supplying video signals to the pixel electrodes 11 extend in the vertical direction of the screen and are arranged in the horizontal direction of the screen, for example. An interlayer insulating film is formed between the scanning line and the video signal line. However, in FIG. 1, details are omitted, and only a state in which the signal line 13 passes through the sealing material 40 and is drawn to the outside is described.

  In FIG. 1, an alignment film 14 is formed on the TFT substrate 10 so as to cover the TFT 12, the pixel electrode 11, and the like. The alignment film 14 determines the initial alignment of the liquid crystal. For example, the alignment film 14 aligns liquid crystal molecules in the rubbing direction by rubbing. The liquid crystal layer 30 is sandwiched between the TFT substrate 10 and the counter substrate 20 on which the color filter 21 and the like are formed.

  A color filter 21 is formed inside the counter substrate 20. The color filter 21 is formed in stripes with the red, green, and blue color filters 21 arranged in parallel. The color filter 21 is not limited to a stripe shape, and may be a delta arrangement or a mosaic arrangement. In general, pixels corresponding to the color of each color filter 21, for example, a red pixel corresponding to a red filter, a green pixel corresponding to a green filter, a blue pixel corresponding to a blue filter, and the like are referred to as sub-pixels. , Blue subpixels are set to form one pixel.

  The color filter 21 is formed in a portion corresponding to the pixel electrode 11 formed on the TFT substrate 10, that is, a portion through which light from the backlight is transmitted. A black matrix 22 is formed between the color filter 21 and the color filter 21. The black matrix 22 is a light shielding film, is formed of a black inorganic or organic film, and is used for the purpose of improving image contrast. The black matrix 22 is also formed above the TFT 12. When light is incident on the TFT 12 from the outside, a photocurrent may flow through the channel portion of the TFT 12 and the TFT 12 may malfunction. The black matrix 22 also has a role as a light shielding film for the external light of the TFT 12.

  The surface on which the color filter 21 and the black matrix 22 are formed is not flat but uneven. If the counter electrode 24 or the alignment film 14 is formed with the unevenness formed, the unevenness is projected onto the alignment film 14 and adversely affects the alignment of the liquid crystal molecules. In FIG. 1, an overcoat film 23 made of an acrylic resin is formed so as to cover the surface on which the color filter 21 and the black matrix 22 are formed, and the surface is flattened.

  A counter electrode 24 is formed on the overcoat film 23. The liquid crystal display device of FIG. 1 is described on the assumption of a so-called TN liquid crystal display device. In the TN method, a vertical electric field is generated between the pixel electrode 11 formed on the TFT substrate 10 and the counter electrode 24 formed on the counter substrate 20 to control the movement of the liquid crystal molecules and transmit the liquid crystal layer 30. Gray scale display is performed by controlling light.

  The liquid crystal display device is not only a method of controlling liquid crystal molecules by a vertical electric field as in the TN method, but also an IPS (In Plane Switching) that controls liquid crystal molecules by an electric field including a component in a direction parallel to the TFT substrate 10 or the counter substrate 20. ) Method exists. In this method, both the counter electrode 24 and the pixel electrode 11 are formed on the TFT substrate 10.

  In FIG. 1, in order to control the transmitted light by the liquid crystal, the layer thickness of the liquid crystal layer 30 must be accurately controlled. For this purpose, a columnar spacer 25 is provided on the counter substrate 20, and the columnar spacer 25 sets an interval between the TFT substrate 10 and the counter substrate 20. The columnar spacer 25 is set at the black matrix 22 portion of the counter substrate 20 and contacts the TFT 12 portion of the TFT substrate 10 or the wiring portion. Therefore, since the columnar spacer 25 does not exist in the pixel electrode 11 portion, unevenness in light transmittance due to the presence of the spacer can be prevented.

  In the counter substrate 20, the alignment film 14 is formed so as to cover the counter electrode 24, the columnar spacer 25, and the like. The initial alignment of the liquid crystal is determined by the alignment direction of the alignment film 14 formed on the TFT substrate 10 and the alignment direction of the alignment film 14 formed on the counter substrate 20.

  In FIG. 1, the liquid crystal layer 30 is sealed by a sealing material 40 formed around the counter substrate 20 and the TFT substrate 10. As the sealing material 40, for example, an epoxy resin is used. Since the sealing material 40 not only seals the liquid crystal, but also has a role of setting a gap between the TFT substrate 10 and the counter substrate 20, the sealing material 40 has a role of a spacer such as resin beads. The member having is dispersed.

  In FIG. 1, a sealing material 40 is provided around the TFT substrate 10 and the counter substrate 20, but a part that is not sealed is left as a liquid crystal sealing hole. Then, liquid crystal is sealed from this sealing hole. After the liquid crystal is sealed, the sealing hole 41 is sealed with the sealing material 41. The sealing material 41 is also formed of a resin such as epoxy.

  When the liquid crystal display panel is enlarged, it takes time to enclose the liquid crystal from the enclosing hole. As a countermeasure against this, for example, the sealing material 40 is installed on the entire circumference of the counter substrate 20, and the liquid crystal is dropped into the sealing material 40. Thereafter, there is a method of sealing the liquid crystal by overlapping the TFT substrate 10 and the counter substrate 20.

  In FIG. 1, a lower polarizing plate 50 is attached to the lower side of the TFT substrate 10. Since the liquid crystal can control only polarized light, the lower polarizing plate 50 converts normal light into linearly polarized light. Then, when the linearly polarized light passes through the liquid crystal layer 30, it is converted into elliptically polarized light, for example. This elliptically polarized light is polarized (analyzed) by the upper polarizing plate 60 affixed to the upper side of the counter substrate 20 to become linearly polarized light again, and is visually recognized by human eyes.

  In FIG. 1, the TFT substrate 10 is formed larger than the counter substrate 20, and a terminal portion is formed at a portion where the TFT substrate 10 is larger than the counter substrate 20. In the terminal portion, terminals for supplying power, video signals, scanning signals, and the like to the liquid crystal display panel from the outside are formed. The terminal portion is connected to an external circuit by connecting a flexible cable (not shown) or the like. In addition, a video signal driving circuit, a scanning signal driving circuit, and the like (not shown) are installed in the terminal portion.

  In FIG. 1, a backlight is installed below the TFT substrate 10. In addition to the light source, the backlight is provided with a diffusion plate, a diffusion sheet, and the like for making light from the light source uniform between the light source and the TFT substrate 10, but is omitted in FIG. Moreover, in a relatively small liquid crystal display device or the like, a light source is installed on the side, a light guide plate for directing the light source toward the liquid crystal display panel, a diffusion sheet for diffusing the light from the light source to be uniform, A prism sheet or the like for efficiently collecting light on the liquid crystal display panel side is installed. However, it is omitted in FIG.

  In FIG. 1, the optical components of the backlight as described above are omitted, and only the light source is shown. In FIG. 1, an LED (Light Emitting Diode) 70 is used as a light source. Conventionally, a cold cathode fluorescent tube (CCFL) has been used as a light source for a backlight. However, the cold cathode fluorescent tube has problems such as being difficult to reduce the size, having a relatively short life, requiring a high driving voltage, and containing mercury. Has been used.

  However, in order to display full color by the liquid crystal display device, the light source of the backlight must be white. As a method for obtaining white color by using an LED, there is a method using a combination of a red LED, a green LED, and a blue LED. As another method of obtaining white color by using an LED, there is a method of using a visible light emitting phosphor in combination with a blue wavelength or long wavelength ultraviolet LED. The method of using a visible light emitting phosphor in combination with a blue wavelength or long wavelength ultraviolet LED has the advantage that the number of LEDs can be reduced. The light source of the present invention uses a light source of a type in which a visible light emitting phosphor is combined with a blue wavelength or long wavelength ultraviolet LED.

  A feature of the present invention is that, as a green color filter, an appropriate amount of a zinc phthalocyanine green pigment (for example, a partially brominated zinc phthalocyanine green pigment such as PG58) and a yellow pigment such as PY150, PY139, or PY138 is mixed. Use things. Further, as a backlight light source, a high-color reproduction pseudo-white LED using a green phosphor and a red phosphor is used for a blue LED. Thereby, in an image formed by the liquid crystal display device, it is possible to form deep green in which the y value of the green degree exceeds 0.71 or 0.71.

  FIG. 5 is a chromaticity diagram in CIE chromaticity coordinates. The horseshoe-shaped part in FIG. 5 is an area covering all colors. There is an NTSC standard as a standard of how much chromaticity can be reproduced. This NTSC standard is a region surrounded by triangles B, R, and G in the horseshoe shape shown in FIG. As an evaluation of the color reproducibility of an image, if the NTSC standard is satisfied, it can be evaluated that the color reproducibility is good.

  In conventional liquid crystal display devices, red and blue have good color reproducibility by color filters, etc., and R and B in FIG. 5 have achieved chromaticity almost equivalent to NTSC R and B. . However, with respect to green, color reproduction is not sufficiently performed as compared with the NTSC standard, and when a conventional green color filter and backlight are used, the chromaticity of G is, for example, as indicated by G1 in FIG. It was a good value. Then, in the conventional liquid crystal display device, even if red and blue have the same color reproducibility as the NTSC standard, the color reproducibility is not sufficient.

  The color reproducibility can be evaluated by the area of the triangle in FIG. The color reproducibility in the conventional liquid crystal display device is evaluated as the area of the triangles B, R, and G1, and this area is defined as T1. NTSC color reproducibility is evaluated as the area of triangles B, R, and G, and this area is T0. Then, the color reproducibility of the conventional liquid crystal display device is T1 / T0 compared with the NTSC standard. Although this value varies depending on the color filter, backlight, etc. used, it was about 77% to 95%. However, the color reproducibility of green and red is assumed to be equivalent to the NTSC standard.

  According to the present invention, by optimizing the green color filter and the light source of the backlight, as shown by the dotted line in FIG. 5, the green chromaticity, particularly the y value, is increased and the overall color reproducibility is improved. It can be made. In FIG. 5, for example, the present invention can make the y value of green larger than the y value in the conventional liquid crystal display device or NTSC standard as G2. As a result, the overall color reproducibility of the liquid crystal display device embodying the present invention is improved. When the blue and red chromaticity values of the liquid crystal display device using the present invention can be reproduced in the same manner as the NTSC standard, the color reproducibility according to the present invention can exceed the color reproducibility of the NTSC standard. That is, in FIG. 5, if the area of a triangle showing the color reproducible range of the present invention is T2, and the area of the triangle showing the color reproducibility according to the NTSC standard is T0, then T2 ≧ T0.

  FIG. 2 shows a combination of a green color filter according to the present embodiment and an LED as a light source, and a case where a green color filter used in a conventional liquid crystal display device is used. This is a comparison of color reproducibility. The evaluation is the color reproducibility in the liquid crystal display device. That is, the characteristics of the actual liquid crystal display device are evaluated, not the color filter alone or the backlight light source alone.

  In FIG. 2, a curve A1 is a characteristic of the liquid crystal display device according to the present invention. In the present invention, a mixture of a zinc phthalocyanine green pigment and a yellow pigment is used as a pigment for the green color filter. Here, as the zinc phthalocyanine green pigment, a partially brominated zinc phthalocyanine green pigment, which is one type thereof, is used, and specifically, a color index number (CI) pigment green (PG) 58 (hereinafter referred to as PG58) is used. . Examples of yellow pigments include C.I. I. Pigment Yellow (PY) 150 (hereinafter PY150) is mixed. Each point is obtained by changing the mixing ratio of the zinc phthalocyanine green pigment (PG58 green pigment) and the PY150 yellow pigment.

  In addition, the manufacturing method of the green color filter in this invention is as follows. That is, a pigment photosensitive dispersion containing zinc phthalocyanine green pigment is formed, and this dispersion is applied. Then, the applied dispersion is solidified by exposure, developed, and then sintered. According to this manufacturing method, since it is not necessary to use a resist, the process can be simplified.

  The light source of the backlight of the liquid crystal display device corresponding to the curve A1 is a combination of a blue LED and a green phosphor and a red phosphor. When such a backlight source is used, in the curve A1 of FIG. 2, when the amount of the zinc phthalocyanine green pigment is G and the amount of PY150 is Y, G / (G + Y) is 55% to 90%. When the ratio was high, the green y value was 0.71 or more, and particularly excellent characteristics could be obtained. The important point is that the use of zinc phthalocyanine green pigment alone does not provide excellent green reproduction characteristics as shown by A1 in FIG. 2, and for the first time, depending on the conditions of combination with the light source of the backlight as described above. This means that high color reproducibility can be obtained. As shown by the curve A1, the green y value in the present invention is close to 0.72, which exceeds the NTSC standard value of green y value 0.71.

  In the curve A1, the shape of the curve is changed at the singular point P1, but the lower side of the point P1 does not use the yellow pigment, uses only the zinc phthalocyanine green pigment, and the zinc phthalocyanine green pigment. This is because the green color filter material is different at the singular point.

  A curve A2 in FIG. 2 is a mixture of PG58, which is a kind of zinc phthalocyanine green pigment, and PY150, which is a kind of yellow pigment, as the pigment of the green color filter, similarly to the curve A1. However, the light source of the backlight of the liquid crystal display device is a combination of a blue LED and a yellow phosphor. Each point in the curve A2 is obtained by changing the ratio of the zinc phthalocyanine green pigment and PY150.

  In the curve A2, the shape of the curve is changed at the singular point P2. This is because the lower side of the point P2 does not use the yellow pigment, uses only the zinc phthalocyanine green pigment, and the zinc phthalocyanine green pigment. This is because the green color filter material is different at the singular point.

  When the curve A1 and the curve A2 according to the present invention are compared, the color reproducibility of A2 is inferior to the present invention. The green y value of the curve A2 does not reach 0.70. Thus, even if the same color filter is used, color reproducibility varies greatly depending on the light source used.

  The curve B1 in FIG. 2 uses a green color filter in which a color index number (CI) pigment green (PG) 36 green pigment and a yellow pigment PY150 are mixed. PG36 is a conventionally used green pigment, and partially brominated copper phthalocyanine is used as the pigment. Moreover, in curve B1, what combined red fluorescent substance and green fluorescent substance with blue LED is used as a light source. That is, the curve B1 uses the same light source as the present invention.

  In the curve B1, each point is obtained by changing the ratio of PG36 and PY150. When the curve B1 is compared with the curve A1 according to the present invention, the green color reproducibility is significantly superior with the curve A1 according to the present invention. The green y value in the curve B1 does not reach 0.68. That is, even when a blue LED combined with a red phosphor and a green phosphor is used as a light source, if a zinc phthalocyanine green pigment is not used as a green color filter, sufficient green reproduction is difficult. .

  The curve B2 in FIG. 2 uses a mixture of a PG36 green pigment and a yellow pigment PY150 as the green color filter, similarly to the curve B1. However, the curve B2 uses a blue LED combined with a yellow phosphor as a light source.

  In the curve B2, each point is obtained by changing the ratio of PG36 and PY150 as in the curve B1. The y value of green in the curve B2 is about 0.64.

  Comparing the curve B2 with the curve A1 according to the present invention, the green color reproducibility is significantly superior with the curve A1 according to the present invention.

  Curve C1 in FIG. 2 uses a green color filter in which a color index number (CI) pigment green (PG) 7 green pigment and a yellow pigment PY150 are mixed. PG7 is a conventionally used green pigment, and copper chloride phthalocyanine is used as the pigment. In the curve C1, a light source in which a blue LED is combined with a red phosphor and a green phosphor is used as the light source. That is, the curve C1 uses the same light source as the present invention.

  In the curve C1, each point is obtained by changing the ratio between PG7 and PY150. When the curve C1 is compared with the curve A1 according to the present invention, the green color reproducibility is significantly superior with the curve A1 according to the present invention. The green y value in the curve C1 does not reach 0.70. That is, even when a blue LED combined with a red phosphor and a green phosphor is used as a light source, if a zinc phthalocyanine green pigment is not used as a green color filter, sufficient green reproduction is difficult. .

  Curve C2 in FIG. 2 uses a mixture of a PG7 green pigment and a yellow pigment PY150 as the green color filter, similarly to curve C1. However, the curve C2 uses a blue LED combined with a yellow phosphor as a light source.

In the curve C2, each point is obtained by changing the ratio of PG7 and PY150 as in the curve C1. The y value of green in the curve C2 is about 0.66.
Comparing the curve C2 and the curve A1 according to the present invention, the green color reproducibility is significantly superior to the curve A1 according to the present invention.

  Curves A1, B1, and C1 in FIG. 2 were obtained by mixing a zinc phthalocyanine green pigment and a yellow pigment of PY150 as a green color filter. Although not shown in FIG. 2, in another experiment, a yellow pigment mixed with zinc phthalocyanine green pigment using PY138 or PY139 was used. As a result, even when PY138 or a green color filter mixed with PY139 and zinc phthalocyanine green pigment was used, results almost similar to those of curves A1, B1, C1, etc. were obtained. In particular, when the amount of the zinc phthalocyanine green pigment is G and the amount of PY138 is Y, corresponding to the curve A1 in FIG. 2, the ratio of G / (G + Y) is 55% to 90% even in the case of PY138. At that time, particularly excellent characteristics could be obtained. The same applies to PY139.

  As described above, this can be realized by using a color filter containing zinc phthalocyanine green pigment as a green color filter and using a blue LED combined with a green phosphor and a red phosphor as a backlight light source. Deep green color reproduction that was not possible becomes possible.

  In addition, as a zinc phthalocyanine green pigment, it is possible to use the partially brominated zinc phthalocyanine green pigment which is the kind. Examples of partially brominated zinc phthalocyanine green pigments include PG58. However, the present invention is not limited to PG58, and any zinc phthalocyanine green pigment can be applied.

  FIG. 3 shows a case where color reproducibility in a liquid crystal display device in which the green color filter described in FIG. 2 and the light source of the backlight are variously combined is compared with the NTSC standard. Among color filters, a red color filter and a blue color filter have conventionally been obtained as color filters that substantially satisfy the NTSC standard. However, a green color filter that satisfies the NTSC standard has not been obtained.

  Therefore, the comparison in FIG. 3 shows that for the red color filter and the blue color filter, when the color filter that satisfies 100% of the NTSC standard is used and the green color filter and the backlight light source are changed, It evaluates whether it satisfies the degree.

  In the table of FIG. 3, LCD is a specification of a liquid crystal display device, and is a combination of a green color filter specification and a specification of a light source used for a backlight. The specifications such as A1 and B1 correspond to the specifications A1 and B1 in FIG. In the table of FIG. 3, BL is a backlight specification. As a backlight light source, a combination of a blue LED with a green phosphor and a red phosphor, and a blue LED with a yellow phosphor. The specification is compared. BLED + GP + RP is a combination of a blue LED, a green phosphor and a red phosphor. BLED + YP is a combination of a blue LED and a yellow phosphor. In the table of FIG. 3, CF is a color filter specification. As a green color filter, a case where a zinc phthalocyanine green pigment (for example, PG58) is included, a case where a PG36 pigment is included, and a case where a PG7 pigment is included are compared. In the table of FIG. 3, ZnG means a green color filter containing a zinc phthalocyanine green pigment (for example, PG58) as a pigment, PG36 means a green color filter containing a PG36 pigment as a pigment, and PG7 as a pigment. It means a green color filter containing PG7 pigment.

  In the table of FIG. 3, “NTSC RATIO” in the bottom column is a comparison of how much each specification can be reproduced compared to the color reproducibility of the NTSC standard. The comparison method compares the areas of the triangles in the CIE chromaticity coordinates in FIG. That is, since it is assumed that blue and red satisfy the NTSC standard 100%, the overall color reproducibility can be achieved by comparing the areas of the triangles in FIG.

  Specifically, the color reproduction characteristic of the NTSC standard is the triangle T0 in FIG. 5, and the color reproducibility with respect to the NTSC standard is T1 when the color reproducibility by the combination of the green color filter of the conventional or comparative example and the backlight light source is T1. Is a triangular area T1 / triangular area T0. In this case, the color reproducibility is lower than 100% with respect to NTSC.

  On the other hand, in a liquid crystal display device having improved green reproduction characteristics, the color reproduction characteristics are represented by a triangle T2 in FIG. The color reproducibility with respect to the NTSC standard is triangular area T2 / triangular area T0. In this case, the color reproducibility becomes higher than 100% with respect to NTSC.

  The NTSC standard colorimetric reproduction rate (NTSC RATIO) in FIG. 3 is a numerical value calculated in this way. In the table of FIG. 3, the NTSC standard colorimetric reproduction rate is the lowest in the specification B2, 81.7%, and the specification A1, which is the liquid crystal display device of the present invention, is the highest. In the table of FIG. 3, only the liquid crystal display device according to the present invention exceeds the NTSC standard. The color reproducibility next to the present invention is the specification A2, that is, the specification A2 in which a green color filter containing a zinc phthalocyanine green pigment is used and a blue LED and a yellow phosphor are combined. However, it is much lower than the color reproducibility in the present invention.

  The specification C1 is the color reproducibility next to the specification A2. That is, this is a case where a green color filter containing a PG7 green pigment is used and a blue LED combined with a green phosphor and a red phosphor is used as a light source of a backlight. Even if only the light source of the backlight is set appropriately, the overall color reproducibility is far below the characteristics of the specification A1 according to the present invention.

  In FIG. 3, the color reproducibility is compared with the NTSC standard. Recently, however, a standard called AdobeRGB has been proposed by Adobe as a standard for evaluating color reproducibility. This standard has begun to be applied to computer monitors and the like. The R, G, B coordinates in the AdobeRGB standard in the CIE chromaticity coordinates are slightly different from the R, G, B coordinates in the NTSC standard.

  In the rightmost column of FIG. 4, R, G, and B chromaticity coordinates in the AdobeRGB standard are shown. When this standard is compared with the chromaticity coordinates of R, G, and B in the NTSC standard shown in the rightmost column of FIG. 3, the standard of AdobeRGB is slightly looser. As a color reproducibility, when compared with the triangular area shown in FIG. 5, the color reproducibility when 100% of the AdobeRGB standard is satisfied is 95.5% compared with the color reproducibility when 100% of NTSC is satisfied. The recall rate.

  Comparing the NTSC standard and the AdobeRGB standard, the chromaticity coordinates of green are the same. On the other hand, blue chromaticity coordinates and red chromaticity coordinates are different in the NTSC standard and the AdobeRGB standard. It is possible to reproduce the blueness and redness of the AdobeRGB standard using a blue color filter or a red color filter used in a conventional liquid crystal display device.

  Therefore, in the table of FIG. 4, the blueness or redness indicates how color reproducibility is when the green color filter and the backlight light source are changed when the AdobeRGB standard is 100% satisfied. Evaluating what will become.

  In the table of FIG. 4, the table headings are the same as in FIG. That is, the LCD is a specification of a liquid crystal display device, and is a combination of a green color filter specification and a specification of a light source used for a backlight. The specifications of A1, B1, etc. correspond to A1, B1, etc. in FIG. In the table of FIG. 4, BL is a backlight specification. As a backlight light source, a specification in which a blue LED is combined with a green phosphor and a red phosphor, and a specification in which a blue LED and a yellow phosphor are combined. And comparing. BLED + GP + RP is a combination of a blue LED, a green phosphor and a red phosphor. BLED + YP is a combination of a blue LED and a yellow phosphor. In the table of FIG. 4, CF is a color filter specification, and when a green color filter includes a zinc phthalocyanine green pigment (for example, PG58), includes a PG36 pigment, and includes a PG7 pigment. In the table of FIG. 4, ZnG means a green color filter containing a zinc phthalocyanine green pigment (for example, PG58) as a pigment, PG36 means a green color filter containing a PG36 pigment as a pigment, and PG7 as a pigment. It means a green color filter containing PG7 pigment.

  In the table of FIG. 4, a blue color filter or a green color filter that satisfies the AdobeRGB standard 100% is used, and the specification A1, which is the present invention, that is, a green color filter containing a zinc phthalocyanine green pigment, and a light source of a backlight The combination of blue LED, red phosphor and green phosphor has the highest color reproduction rate. In this case, the color reproduction rate is 97.6% as compared with the NTSC standard.

  When the AdobeRGB standard is 100% satisfied, the color reproduction rate is 95.5% with respect to the NTSC standard, and therefore the color reproduction rate of the AdobeRGB standard can be exceeded by using the present invention.

  In the table of FIG. 4, the liquid crystal display device having the next best color reproducibility after the liquid crystal display device of the present invention is the specification A2, and the color reproduction rate of the NTSC standard is 91.4%. Next, the specification is C1, and the color reproduction rate of the NTSC standard is 90.9%. When the color reproduction rates in the respective specifications are compared, the order is the same as in the case of FIG.

  As shown in FIG. 4, when the color reproduction ratios of blue and red are 100% satisfying the AdobeRGB standard, the overall color reproduction ratio when the green color filter and the light source of the backlight are changed is shown in FIG. Only exceeds the AdobeRGB standard. Further, it can be seen that the color reproduction rate of the present invention may be conspicuous even when compared with the specification A2 or the like having the next highest color reproduction rate of the present invention.

  As described above, a liquid crystal display device with excellent color reproducibility can be realized by using the configuration of the present invention.

It is a cross-sectional schematic diagram of the liquid crystal display device of this invention. It is the figure which compared the color reproducibility of the green area | region in the CIE chromaticity diagram of this invention and a comparative example. It is a table | surface which compares this invention and a comparative example. It is a table | surface which compares this invention and a comparative example. It is a chromaticity diagram in CIE chromaticity coordinates.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... TFT substrate, 11 ... Pixel electrode, 12 ... TFT, 13 ... Signal line, 14 ... Orientation film, 20 ... Counter substrate, 21 ... Color filter, 22 ... Black matrix, 23 ... Overcoat film, 24 ... Counter electrode, 25 ... Columnar spacers, 30 ... Liquid crystal layer, 40 ... Sealing material, 41 ... Sealing material, 50 ... Lower polarizing plate, 60 ... Upper polarizing plate, 70 ... LED

Claims (9)

A liquid crystal display panel in which a liquid crystal layer is sandwiched between a TFT substrate on which a TFT and a pixel electrode are formed, a counter substrate disposed opposite to the TFT substrate, and a backlight disposed on the back surface of the liquid crystal display panel A liquid crystal display device having
The TFT substrate or the counter substrate includes a color filter, the color filter includes a red filter, a blue filter, and a green filter, and the green filter includes a zinc phthalocyanine green pigment,
The backlight includes a light source that is a combination of a blue LED, a red phosphor, and a green phosphor.   The liquid crystal display device according to claim 1, wherein the green CIE chromaticity value emitted from the liquid crystal display device has a y value of 0.71 or more.   2. The liquid crystal display device according to claim 1, wherein the green CIE chromaticity value emitted from the liquid crystal display device has a y value larger than 0.71.   The green color filter includes the zinc phthalocyanine green pigment and the yellow pigment, and when the amount of the zinc phthalocyanine green pigment is G and the amount of the yellow pigment is Y, 0.55 ≦ G / (G + Y) ≦ The liquid crystal display device according to claim 1, wherein the liquid crystal display device is 0.90.   The liquid crystal display device according to claim 4, wherein the yellow pigment is PY150.   The liquid crystal display device according to claim 4, wherein the yellow pigment is PY138 or PY139.   7. The liquid crystal display device according to claim 1, wherein the green color filter is formed using a photosensitive dispersion liquid containing the zinc phthalocyanine green pigment.   The liquid crystal display device according to claim 1, wherein the zinc phthalocyanine green pigment of the green color filter is a partially brominated zinc phthalocyanine green pigment.   The liquid crystal display device according to claim 8, wherein the partially brominated zinc phthalocyanine green pigment is PG58.

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