JP2013029548A - Backlight and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a backlight with which a liquid crystal display device capable of performing desired blue display and excellent in color reproducibility can be obtained, and to provide a liquid crystal display device using the backlight.SOLUTION: The backlight includes a light source having: a first light source, which includes a near UV light-emitting element and a phosphor layer containing a red phosphor and a green phosphor and formed to cover the near UV light-emitting element; and a second light source, which includes a blue light-emitting diode.

Description

  The present invention relates to a backlight that can exhibit high color reproducibility when used in a liquid crystal display device, and a liquid crystal display device using the backlight.

  The liquid crystal display device has features such as power saving, light weight, thinness, and the like, and has rapidly spread in recent years in place of the conventional CRT display. The liquid crystal display device includes a backlight, a liquid crystal layer, and a color filter.

Although the liquid crystal display device has the above-described advantages over the CRT display, the display quality of the image is inferior to that of the CRT display, and is particularly required to improve color reproducibility.
The color reproducibility of the liquid crystal display device is determined by the emission wavelength (emission peak) of the backlight and the color characteristics of the color filter.

Here, as the light source of the backlight, a mercury gas excited fluorescent lamp tube (FL), a cold cathode tube (CCFL) having emission peaks in the red, green, and blue wavelength regions are conventionally used. However, since FL and CCFL have sub-light emission other than the red, green, and blue wavelength regions, there is a concern that the color purity may deteriorate. In view of this, use of a light-emitting diode that does not have sub-light emission (hereinafter sometimes referred to as an LED) instead of FL or CCFL as a light source of the backlight is being studied.
In addition, LEDs have advantages such as excellent responsiveness, long life, low voltage drive, and excellent environmental conservation because they are mercury-free compared to FL and CCFL.

As a backlight using such an LED light source, for example, Patent Document 1 discloses a blue LED that emits light (blue light) having an emission peak in a blue light region (435 nm to 460 nm), and a blue light that absorbs blue light. A backlight having a light source that combines a red phosphor that emits light having a light emission peak in the red light region or the green light region (red light or green light) and a translucent resin in which the green phosphor is dispersed is disclosed. ing. The backlight having the light source combines white light by combining three colors of light: blue light emitted from a blue LED, red light emitted from a red phosphor, and green light emitted from a green phosphor. It is presented.
However, in the backlight having the above-described configuration, there are cases where a red phosphor or a green phosphor capable of absorbing the blue light and emitting desired red light or green light is limited. When used in the above, there is a problem that it is difficult to achieve desired color reproducibility.

JP 2009-198534 A International Publication WO2009 / 144922 Pamphlet International Publication WO 2010/103767 Pamphlet

  Therefore, as a backlight using an LED light source, as shown in Patent Document 2 and Patent Document 3, a near-ultraviolet light-emitting element having a light emission peak in the near-ultraviolet light region (360 nm to 430 nm), a red phosphor, and a green fluorescence The structure which combined the body and the fluorescent substance layer containing a blue fluorescent substance is examined. In the backlight having the above-described configuration, it is possible to expand the degree of freedom of selection of each color phosphor that can be used in the phosphor layer, and the liquid crystal display device as compared with the backlight using the blue LED described above. The color reproducibility of the image can be improved.

  However, with respect to the blue phosphor used in the phosphor layer, there is a problem that no substance capable of absorbing near ultraviolet light and emitting desired blue light has been found at present. Therefore, in the liquid crystal display device using the backlight having the above-described configuration, it is difficult to perform a desired blue display, and as a result, it is difficult to achieve sufficient color reproducibility of the liquid crystal display device. There is a problem.

  The present invention has been made to solve the above-described problems, and a backlight capable of performing a desired blue display and obtaining a liquid crystal display device excellent in color reproducibility, and A main object is to provide a liquid crystal display device using the same.

  In order to solve the above-described problems, the present invention provides a near-ultraviolet light emitting element, and a first light source including a phosphor layer formed to cover the near-ultraviolet light emitting element and containing a red phosphor and a green phosphor, There is provided a backlight comprising a light source having a second light source having a blue LED.

  According to the present invention, since a light source having two light sources, a first light source having a near-ultraviolet light emitting element and a phosphor layer, and a second light source having a blue LED, the desired red light region and green light region are provided. It is possible to obtain red light and green light having a light emission peak of from the first light source, and blue light having a light emission peak in a desired blue light region can be obtained from the second light source. Therefore, in the liquid crystal display device using the backlight of the present invention, the chromaticity coordinates of each color of red, green, and blue shown in the XYZ xy chromaticity diagram can be within a desired range. It is possible to make the liquid crystal display device excellent in color reproducibility.

  In the present invention, the backlight is preferably an edge light type backlight. This is because the first light source and the second light source can be easily arranged in a predetermined pattern so as to exhibit uniform white light in the entire backlight.

  The present invention includes the above-described backlight, a color filter having a red colored layer, a green colored layer, and a blue colored layer, a liquid crystal driving element substrate having a liquid crystal driving element, a counter substrate, and the liquid crystal driving element substrate and There is provided a liquid crystal display device comprising a liquid crystal cell having a liquid crystal layer disposed between the opposing substrates.

  According to the present invention, since the backlight emits white light having emission peaks in desired red light region, green light region, and blue light region, in the liquid crystal display device of the present invention, XYZ. The chromaticity coordinates of the red, green, and blue colors shown in the xy chromaticity diagram of the system can be within a desired range, and a liquid crystal display device having excellent color reproducibility can be obtained.

  In the present invention, the color filter has a chromaticity coordinate of the red colored layer of 0.650 <x <0.670 and 0.320 <y <0.345, and a chromaticity coordinate of the green colored layer of 0. .265 <x <0.295, 0.585 <y <0.610, and the chromaticity coordinates of the blue colored layer are 0.130 <x <0.150 and 0.08 <y <0.140. In the backlight, when the intensity of the emission peak in the near ultraviolet light region of the first light source is 1, the intensity of the emission peak of the blue light emitting diode of the second light source is 0.65 to 2. It is preferable that the number ratio of the first light source and the second light source is adjusted so as to be within the range of 75. By using the color filter and the backlight, a liquid crystal display device having more excellent color reproducibility can be obtained.

  INDUSTRIAL APPLICABILITY The present invention has an effect of providing a backlight capable of performing a desired blue display and capable of obtaining a liquid crystal display device excellent in color reproducibility, and a liquid crystal display device using the backlight. .

It is the schematic which shows an example of the backlight of this invention. It is a schematic plan view which shows the other example of the backlight of this invention. It is a schematic sectional drawing which shows an example of the liquid crystal display device of this invention.

  Hereinafter, the backlight and the liquid crystal display device of the present invention will be described.

A. Backlight Hereinafter, the backlight of the present invention will be described.
A backlight according to the present invention includes a near-ultraviolet light emitting element, a first light source including a phosphor layer formed to cover the near-ultraviolet light emitting element and containing a red phosphor and a green phosphor, and a blue LED. And a light source having two light sources.

  The backlight of the present invention will be described with reference to the drawings. Fig.1 (a) is a schematic plan view which shows an example of the backlight of this invention, FIG.1 (b) is the sectional view on the AA line of Fig.1 (a). As shown in FIGS. 1A and 1B, the backlight 10 of the present invention is formed so as to cover the near-ultraviolet light-emitting element 11 and the near-ultraviolet light-emitting element 11, and the red phosphor 12R and the green phosphor 12G. The light source 3 which has the 1st light source 1 provided with the fluorescent substance layer 13 containing, and the 2nd light source 2 which has blue LED is provided. Further, the backlight 10 of the present invention may have a light source substrate 4 that supports the light source 3. FIGS. 1A and 1B show an example in which the backlight 10 is an edge light type backlight. In this case, the light guide plate 5 is usually used in addition to the light source 3.

FIG. 2 is a schematic plan view showing another example of the backlight of the present invention. FIG. 2 shows an example in which the backlight of the present invention is a direct type backlight. In this case, the light source 3 usually has a configuration in which the first light source 1 and the second light source 2 are arranged over the entire plane on which the liquid crystal display device is arranged. In FIG. 2, the first light source 1 has an arrangement pattern in which the arrangement directions (the horizontal direction x, the vertical direction y, and the diagonal distance u) of one second light source 2 and another second light source 2 are equal. An example in which the second light sources 2 are arranged is shown.
Note that reference numerals that are not described in FIG. 2 can be the same as those described in FIG. 1, and thus description thereof is omitted here.

  As described above, in a backlight having a light source that combines a conventional near-ultraviolet LED and a phosphor layer containing a red phosphor, a green phosphor, and a blue phosphor, when used in a liquid crystal display device Therefore, it is difficult to perform a desired blue display, and as a result, there is a problem that it is difficult to achieve sufficient color reproducibility of the liquid crystal display device. The reason will be described below.

First, the color reproducibility of the liquid crystal display device will be described.
In general, the color reproducibility of a display is expressed as the NTSC ratio of the display. Here, the NTSC ratio of the display means that the color range that can be reproduced by the NTSC system (color reproduction range) shown by the chromaticity diagram defined by the CIE (International Lighting Commission) is 100%. The color reproduction range is expressed as a ratio.
NTSC refers to the standard of the color television broadcasting system.
The chromaticity diagram is expressed by chromaticity coordinates by replacing red, green, and blue with numerical values in an xy chromaticity diagram of the XYZ color system, for example. In the chromaticity diagram, the color reproduction range is indicated by a triangle formed by connecting the chromaticity coordinates of red, green, and blue with a straight line. Therefore, the wider the color reproduction range, the larger the area of the triangle in the chromaticity diagram. Therefore, the color reproducibility of the liquid crystal display device is indicated by the size of the area of a triangle formed by connecting the red chromaticity coordinate, the green chromaticity coordinate, and the blue chromaticity coordinate with a straight line in the chromaticity diagram of the liquid crystal display device. It is determined by the position of each chromaticity coordinate.

  Here, in a backlight having a conventional near-ultraviolet LED and a light source having a phosphor layer, a blue phosphor capable of absorbing near-ultraviolet light and emitting desired blue light has not been found at present. Therefore, the blue phosphor actually used often has a light emission peak on the longer wavelength side than the blue light region. Moreover, since the blue colored layer of the color filter used for the liquid crystal display device together with the backlight transmits the light in the blue light region described above, a backlight using a conventional light source is used for the liquid crystal display device. In this case, since the light from the light source does not include the emission peak of the desired blue light region, it is difficult to perform the desired blue display. Therefore, when such a liquid crystal display device is shown in a chromaticity diagram, the blue chromaticity coordinates are not the desired coordinates, and the area of the triangle connecting the red, green, and blue coordinates with straight lines is small. Therefore, the color reproducibility is inferior.

  In order to solve the above-mentioned problems, the present invention finds that a blue LED is used as a blue light source that changes to a blue phosphor that has been difficult to obtain blue light having an emission peak in a desired blue light region, As a configuration of the backlight, it has a great feature in that a configuration using a near-ultraviolet light emitting element and a blue LED in combination is adopted.

  According to the present invention, since a light source having two light sources, a first light source having a near-ultraviolet light emitting element and a phosphor layer, and a second light source having a blue LED, the desired red light region and green light region are provided. It is possible to obtain red light and green light having a light emission peak of from the first light source, and blue light having a light emission peak in a desired blue light region can be obtained from the second light source. Therefore, in the liquid crystal display device using the backlight of the present invention, the chromaticity coordinates of each color of red, green, and blue shown in the XYZ xy chromaticity diagram can be within a desired range. It is possible to make the liquid crystal display device excellent in color reproducibility.

  In addition, according to the present invention, since a blue LED having a smaller energy than that of a near-ultraviolet light emitting element is used in combination, it is possible to extend the lifetime as compared with a backlight having a conventional light source.

  Hereinafter, details of the backlight of the present invention will be described.

1. A light source used in the present invention includes a near-ultraviolet light emitting element, a first light source formed so as to cover the near-ultraviolet light emitting element, and having a phosphor layer containing a red phosphor and a green phosphor, and a blue light emitting diode A second light source.

(1) Structure of light source In the present invention, there is no particular limitation as long as it has at least one first light source and at least one second light source. The first light source and the second light source may have the same shape and size, or may have different shapes and sizes, but have the same shape and size. It is more preferable to have it. This is because the intensity of each light emission peak of red light, green light, and blue light can be easily adjusted to a desired level by adjusting the number ratio of the first light source and the second light source. This is because it is easy to arrange in a pattern.

  The number ratio of the first light source and the second light source in one backlight is not particularly limited as long as it can exhibit uniform white light and does not cause color unevenness when used in a liquid crystal display device. Not. Note that “the backlight exhibits uniform white light” means that unevenness of light of a specific wavelength such as red light, green light, yellow light, and blue light does not occur when the entire backlight is observed. Point to. In addition, for example, non-uniformity of light does not occur in the backlight, for example, using a luminance meter (SR-3AR manufactured by Topcon Co., Ltd.) on the display surface of a liquid crystal display device that displays white, and xy chromaticity and Y value Evaluation can be made by measuring (lightness) at a plurality of positions and confirming that the difference in xy chromaticity is within ± 1/500 and that Y is within 3%.

  Here, regarding the number ratio of the first light source and the second light source, the intensity of the emission peak of red light and green light emitted from the first light source and the intensity of the emission peak of blue light emitted from the second light source are adjusted. It is preferable to adjust the number ratio so that it can be performed. The intensity of the emission peak of red light and green light emitted from the first light source correlates with the intensity of the emission peak of the near ultraviolet light region of the first light source, and the emission peak of the near ultraviolet light region of the first light source. The stronger the intensity, the stronger the emission peak intensity of red light and green light. Further, the intensity of the emission peak of the blue light emitted from the second light source is determined by the intensity of the emission peak of the blue LED. Therefore, in the present invention, the first light source and the second light source can be adjusted so that the ratio of the intensity of the light emission peak in the near ultraviolet light region of the first light source and the intensity of the light emission peak of the blue LED can be adjusted. It is preferable to adjust the number ratio.

  Here, in the liquid crystal display device, the color reproducibility is determined by the light emission peak of each color light of the backlight and the color characteristics of the color filter used in the liquid crystal display device. Therefore, the number ratio of the first light source and the second light source described above is preferably adjusted in consideration of the color characteristics of the color filter used in combination with the backlight of the present invention when a liquid crystal display device is used.

  More specifically, the backlight of the present invention has the following color filter, that is, the chromaticity coordinates of the red colored layer are 0.650 <x <0.670, 0.320 <y <0.345, and the green color. The chromaticity coordinate of the colored layer is 0.265 <x <0.295 and 0.585 <y <0.610, the chromaticity coordinate of the blue colored layer is 0.130 <x <0.150, and When used in combination with a color filter where 08 <y <0.140, the intensity of the emission peak of the blue light emitting diode of the second light source is 1 when the intensity of the emission peak of the first light source in the near ultraviolet region is 1. The first light source of the backlight and the above so as to be in the range of 0.65 to 2.75, in particular in the range of 0.67 to 2.69, particularly in the range of 0.85 to 2.69. It is preferable that the number ratio of the second light sources is adjusted. Arbitrariness. It becomes possible to improve the color reproducibility of the liquid crystal display device. Note that the color filter and the like used in the backlight of the present invention will be described in the section “B. Liquid crystal display device” described later, and thus description thereof is omitted here.

  The specific number ratio of the first light source and the second light source is appropriately selected depending on the form of the backlight of the present invention, the application, and the like. First light source: second light source = 5: 5 to 9 Is preferably in the range of 1: 4, particularly in the range of 6: 4 to 9: 1, in particular in the range of 7: 3 to 9: 1.

  In addition, the total number of the first light source and the second light source used for the light source in the present invention is appropriately selected depending on the form of the backlight of the present invention, the application, etc. Within the range, it is particularly preferable to be within the range of 50 to 800, particularly within the range of 50 to 700.

The arrangement of the first light source and the second light source is not particularly limited as long as the entire backlight can exhibit a uniform white color, and is appropriately selected depending on the form of the backlight. be able to.
For example, when the backlight of the present invention is an edge light type backlight as shown in FIG. 1, the first light source and the second light source are arranged along at least one side surface (all side surfaces in FIG. 1) of the light guide plate. Light sources are arranged.
On the other hand, when the backlight of the present invention is a direct type backlight as shown in FIG. 2, the first light source and the second light source are arranged on a plane on which the liquid crystal display device is arranged.

Further, the arrangement pattern of the first light source and the second light source is not particularly limited as long as it can exhibit a desired color reproducibility when the backlight of the present invention is used in a liquid crystal display device. It can be appropriately selected depending on the application.
For example, when the backlight of the present invention is an edge-light type backlight, a predetermined number of first light sources and second light sources are provided (three first light sources 1 and second light sources in FIG. 1A). 1)) can be cited.
On the other hand, for example, when the backlight of the present invention is a direct type backlight, the second light sources are not adjacent to each other in the light source arrangement direction, and one second light source to another second light source or installation light source. The pattern which arrange | positions a 1st light source and a 2nd light source so that the distance to an edge part (a 1st light source or a 2nd light source) may become uniform can be mentioned.

(2) Configuration of light source The light source in the present invention has a first light source and a second light source.

(I) 1st light source The 1st light source in this invention has a near-ultraviolet light emitting element and a fluorescent substance layer.

(A) Near-ultraviolet light-emitting element The near-ultraviolet light-emitting element used in the present invention is a light source element having an emission peak wavelength in the range of 360 nm to 430 nm.

  Such a near-ultraviolet light-emitting element is not particularly limited as long as a light emission peak exists in the above-described wavelength region, and examples thereof include a near-ultraviolet LED and a near-ultraviolet laser. In the present invention, a near-ultraviolet LED is particularly preferable.

  Specific examples of the near-ultraviolet LED include various types of InGaN-based, GaN-based, and AlGaN-based LEDs.

(B) Phosphor layer The phosphor layer in the present invention has a phosphor layer containing a red phosphor and a green phosphor. The phosphor layer is formed so as to cover the above-described near-ultraviolet light emitting element.

  The phosphor layer is usually formed by dispersing the phosphors of the above-described colors in the resin layer.

The red phosphor used in the phosphor layer is not particularly limited as long as it can absorb near ultraviolet light and emit red light. _{Specifically,} (wherein, x1 is, 0.01 <x1 <0.15) ( La 1-X1, Eu x1) 2 O 2 S and europium-activated lanthanum oxysulfide phosphor represented by, (Y _1-x2 , Eu _x2 ) ₂ O ₂ S (wherein x2 is 0.01 <x2 <0.15), a europium activated yttrium oxysulfide phosphor, and the like. These red phosphors may be used alone or in combination of two or more.

  Further, the content of the red phosphor in the phosphor layer is not particularly limited as long as the desired red light emission can be obtained. Specifically, the content of the red phosphor is based on the total solid content of the phosphor layer. It is preferable to be in the range of 3% to 15% by mass, especially in the range of 4% to 13% by mass, and particularly in the range of 5% to 12% by mass. This is because when the content of the red phosphor is less than the above range, it may be difficult to obtain desired red light emission. Moreover, it is because it may become difficult to form fluorescent substance layer itself when content of red fluorescent substance exceeds the said range.

The green phosphor is not particularly limited as long as it can absorb near-ultraviolet light and emit green light. For example, (Sr _{2−x−y−u−} Ba _x Mg _y) Eu _z Mn _u ) SiO ₄ (wherein x, y, z, u are 0.1 <x <1.0, 0 ≦ y <0.21, 0.05 <z <0.3, 0 ≦ A divalent europium activated silicate phosphor represented by u <0.04) can be mentioned. Further, during Among green phosphor as described above _{(Sr 2-x-y-} z-u Ba x Mg y Eu z Mn u) SiO 4 ( wherein, x, y, z, u is, 0.1 <x <1.0, 0.005 <y <0.21, 0.05 <z <0.3, 0.001 <u <0.04) are preferably used. Moreover, as a green fluorescent substance, only 1 type may be used and 2 or more types may be used.

  Further, the content of the green phosphor in the phosphor layer is not particularly limited as long as desired green light emission can be obtained. Specifically, the content of the green phosphor is based on the total solid content of the phosphor layer. It is preferably in the range of 5% by mass to 20% by mass, in particular in the range of 6% by mass to 19% by mass, particularly in the range of 7% by mass to 18% by mass. This is because, when the content of the green phosphor is less than the above range, it may be difficult to obtain desired green light emission. Moreover, it is because it may become difficult to form fluorescent substance layer itself when content of green fluorescent substance exceeds the said range.

  The phosphor layer in the present invention is not particularly limited as long as it contains the above-described red phosphor and green phosphor, and may contain phosphors emitting other colors. In the present invention, it is particularly preferable to contain a blue phosphor. This is because when the backlight of the present invention is used in a liquid crystal display device, the luminance of the blue pixel can be further improved.

The blue phosphor is not particularly limited as long as desired blue light emission can be obtained. For example, (M2, Eu) ₁₀ (PO ₄ ) ₆ · Cl ₂ (wherein M2 is Mg, Ca , At least one element selected from Sr and Ba), and a divalent europium-activated halophosphate phosphor represented by a (M3, Eu) O.bAl ₂ O _3. Aluminate phosphors can be mentioned. Moreover, as such blue fluorescent substance, only 1 type may be used and 2 or more types may be used.

  Further, the content of the blue phosphor in the phosphor layer is not particularly limited as long as the desired blue light emission can be obtained. Specifically, the content of the blue phosphor is based on the total solid content of the phosphor layer. It is preferable to be in the range of 3% to 15% by mass, especially in the range of 4% to 13% by mass, and particularly in the range of 5% to 12% by mass. This is because if the content of the blue phosphor is less than the above range, it may be difficult to obtain desired blue light emission. Moreover, it is because it may become difficult to form fluorescent substance layer itself, when content of blue fluorescent substance exceeds the said range.

Examples of the resin layer used for the phosphor layer include resins such as polymethyl methacrylate, polyacrylate, polycarbonate, polyvinyl alcohol, polyvinyl pyrrolidone, hydroxyethyl cellulose, and carboxymethyl cellulose. A silicone resin can also be used.
Further, when the phosphor layer is patterned by a photolithography method, a photosensitive resin can be used as the matrix resin. Examples of the photosensitive resin include photocurable photosensitive resins having reactive vinyl groups such as acrylic acid, methacrylic acid, polyvinyl cinnamate, and cyclized rubber.
Furthermore, when a printing method or an inkjet method is used as a method for forming the fluorescent layer, an ink containing a matrix resin is used. Examples of the matrix resin used in this case include melamine resin, phenol resin, alkyd resin, epoxy resin, polyurethane resin, polyester resin, maleic resin, polyamide resin monomer, oligomer or polymer, polymethyl methacrylate, poly Examples of the resin include acrylate, polycarbonate, polyvinyl alcohol, polyvinyl pyrrolidone, hydroxyethyl cellulose, and carboxymethyl cellulose.

  The thickness of such a phosphor layer is not particularly limited as long as it can sufficiently absorb light from the near-ultraviolet light emitting element and emit fluorescence. Specifically, it can be appropriately set in consideration of the fluorescent dye to be used, the concentration of the fluorescent dye, and the like, for example, about 5 μm to 15 μm.

  As a method for forming the phosphor layer, a phosphor and resin are mixed, dispersed or solubilized to prepare a phosphor layer forming coating solution, and this phosphor layer forming coating solution is generally used for spin coating, roll coating, etc. A method of applying by a general coating method and patterning by a photolithography method, or a method of patterning by a printing method such as screen printing or an ink jet method using the phosphor layer forming coating solution is used. Further, as a method for forming the fluorescent layer, a method of forming a film by a vacuum deposition method or a sputtering method through a predetermined mask can be used.

(Ii) Second light source The second light source in the present invention has a blue LED.

  Such a blue LED is not particularly limited as long as it has a light emission peak in the wavelength range of 435 nm to 460 nm, and a known LED can be used.

2. Other Configurations The backlight of the present invention is not particularly limited as long as the first light source and the second light source described above are arranged, and other necessary configurations can be appropriately selected and used. Hereinafter, such a configuration will be described.

(1) Light Diffusing Layer The backlight of the present invention may have a light diffusing layer on the side where the liquid crystal display device is disposed. The light diffusion layer has a function of improving the light utilization efficiency by diffusing light from the backlight. As such a light diffusing layer, a publicly known one in a general backlight can be used, and examples thereof include those in which fine particles having a light diffusing function are dispersed in a transparent resin layer.

(2) Light guide plate When the backlight of the present invention is an edge light type, a light guide plate is usually used in combination. The light guide plate is provided on the side of the light source, and the light of the light source is incident from the side surface (light incident surface) of the light guide plate, and the light is repeatedly reflected on a pair of main surfaces facing the light guide plate. It has a function of emitting uniform light from the entire light exit surface of the light guide plate.

  Since such a light guide plate can be the same as that used for a general edge light type backlight, description thereof is omitted here.

  In addition, the light guide plate may have a reflective layer, a prism layer, or the like as necessary. Since these layers can be the same as those used for a light guide plate of a general edge light type backlight, description thereof is omitted here.

3. Backlight As a form of the backlight of the present invention, an edge light type or a direct type may be used, but an edge light type is preferable. This is because the first light source and the second light source can be easily arranged in a predetermined pattern so as to exhibit uniform white light throughout the backlight.

  The backlight of the present invention is used as a light source for a transmissive liquid crystal display device.

4). Backlight Manufacturing Method The backlight manufacturing method used in the present invention is not particularly limited as long as it is a method capable of manufacturing a backlight having the above-described configuration, and is the same as a general backlight manufacturing method. The description here is omitted.

B. Next, the liquid crystal display device of the present invention will be described.
The liquid crystal display device of the present invention includes a backlight described in the above section “A. Backlight”, a color filter having a red colored layer, a green colored layer, and a blue colored layer, and a liquid crystal driving element having a liquid crystal driving element. A liquid crystal display device comprising: a base material; a counter base material; and a liquid crystal cell having a liquid crystal layer disposed between the liquid crystal driving element base material and the counter base material.

Here, the liquid crystal display device of the present invention will be described with reference to the drawings. FIG. 3 is a schematic cross-sectional view showing an example of the liquid crystal display device of the present invention. As shown in FIG. 3, the liquid crystal display device 100 of the present invention includes a backlight 10 and a liquid crystal cell 30.
The liquid crystal cell 20 includes a color filter base material (opposing base material) 21, a color filter 20 formed on the counter base material 21, and having a red coloring layer 22R, a green coloring layer 22G, and a blue coloring layer 22B. The liquid crystal driving element base material 31 having a liquid crystal driving element and the liquid crystal layer 32 disposed between the liquid crystal driving element base material 31 and the counter base material 21 are provided. In the present invention, the color filter 20 may have a light shielding portion 23 between the colored layers.

  According to the present invention, since the backlight emits white light having emission peaks in desired red light region, green light region, and blue light region, in the liquid crystal display device of the present invention, XYZ. The chromaticity coordinates of the red, green, and blue colors shown in the xy chromaticity diagram of the system can be within a desired range, and a liquid crystal display device having excellent color reproducibility can be obtained.

  Hereinafter, each structure of the liquid crystal display device of this invention is demonstrated.

1. Backlight Since the backlight according to the present invention has been described in the above-mentioned section “A. Backlight”, description thereof is omitted here.

2. Liquid Crystal Cell The liquid crystal cell in the present invention has a color filter, a liquid crystal driving element substrate, a counter substrate, and a liquid crystal layer. Each configuration will be described below.

(1) Color filter The color filter in this invention is demonstrated.
The color filter of the present invention has a colored layer including a red colored layer, a green colored layer, and a blue colored layer. The color filter is configured by forming a colored layer on either a color filter substrate or a liquid crystal driving element substrate described later.

(I) Colored layer The colored layer in this invention is demonstrated. The colored layer in the present invention is not particularly limited as long as it has a red colored layer, a green colored layer, and a blue colored layer, and can have a colored layer other than the above-described colors as necessary. An example of such a colored layer is a yellow colored layer.

The colored layer is not particularly limited as long as it can exhibit a desired color reproducibility when used in a liquid crystal display device, but the chromaticity coordinate of the red colored layer is 0.650 <x <0. .670 and 0.320 <y <0.345, in particular 0.652 <x <0.670 and 0.320 <y <0.343, especially 0.654 <x <0.670 and 0.320 <. It is preferable to show y <0.339. Further, the chromaticity coordinates of the green colored layer are 0.265 <x <0.295 and 0.585 <y <0.610, in particular 0.265 <x <0.293 and 0.587 <y <0. It is preferable to show 610, particularly 0.265 <x <0.291 and 0.593 <y <0.610. The chromaticity coordinates of the blue colored layer are 0.130 <x <0.150 and 0.08 <y <0.140, in particular 0.134 <x <0.147 and 0.08 <y <0. .130, in particular 0.134 <x <0.145 and 0.105 <y <0.124. When the chromaticity coordinate of the colored layer of each color is within the above range, the liquid crystal display device of the present invention can be made excellent in color reproducibility.
The chromaticity coordinates of the colored layer described above are chromaticity coordinates in the xy chromaticity diagram of the XYZ color system. Further, the chromaticity coordinates are measured using a C light source and a microspectroscopic device OSP-SP2000 (manufactured by OLYMPUS), and then, from the obtained transmission spectrum, chromaticity coordinates (x, y). Can be obtained by calculating from Equation 1 below.

  Such a colored layer is usually formed by dispersing a colorant in a resin layer.

The colorant is not particularly limited as long as it can perform a desired color display using the liquid crystal display device of the present invention.
For example, as a red colorant, C.I. I. Pigment red 177, C.I. I. Pigment red 242, C.I. I. Pigment red 254, C.I. I. Pigment yellow 139, C.I. I. One or more pigments selected from the group consisting of CI Pigment Yellow 150 can be suitably used.
Examples of the green colorant include C.I. I. Pigment green 58, C.I. I. Pigment yellow 138, C.I. I. Pigment yellow 139, C.I. I. One or more pigments selected from the group consisting of CI Pigment Yellow 150 can be suitably used.
Examples of blue colorants include C.I. I. Pigment blue 15: 1, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 15: 4, C.I. I. One or more pigments selected from the group consisting of CI Pigment Blue 15: 6 and zinc phthalocyanine pigments can be suitably used.

  About resin used for a colored layer, since it can be made to be the same as that used for the colored layer of a general color filter, description here is abbreviate | omitted.

  The colored pattern shape in the colored layer can be a known arrangement such as a stripe type, a mosaic type, a triangle type, or a four-pixel arrangement type, and the colored area can be arbitrarily set.

  In addition, the thickness of the colored layer used in the present invention is not particularly limited as long as it is a thickness capable of performing a desired color display in the liquid crystal display device of the present invention. You can choose.

  The material and the forming method used for the colored layer can be the same as the material and the forming method used for the colored layer of a general color filter, and thus description thereof is omitted here.

(Ii) Other configurations In addition to the above-described colored layer, the color filter in the present invention can be appropriately added with a necessary configuration. Such a configuration includes a color filter base material for supporting the colored layer, a light shielding portion formed between the colored layers to partition the pixels, and a columnar spacer for maintaining a distance between the color filter and a counter substrate described later. And an overcoat layer for protecting the colored layer. Since these configurations can be the same as those used for a general color filter, description thereof is omitted here.

  The color filter substrate can also be used as a counter substrate described later.

(2) Liquid crystal drive element substrate and counter substrate The liquid layer drive element substrate and counter substrate used in the present invention are appropriately selected and used according to the driving method of the liquid crystal display device in the present invention. it can.

  The driving method of the liquid crystal display device is not particularly limited, and a driving method generally used for a liquid crystal display device can be employed. Examples of such a drive method include a TN method, an IPS method, an OCB method, and an MVA method. In the present invention, any of these methods can be preferably used.

(3) Liquid Crystal Layer The liquid crystal layer in the present invention is provided between the liquid crystal driving element substrate and the counter substrate. As the liquid crystal constituting the liquid crystal layer, various liquid crystals having different dielectric anisotropy and mixtures thereof can be used according to the driving method of the liquid crystal display device of the present invention.

As a method for forming the liquid crystal layer, a method generally used as a method for manufacturing a liquid crystal cell can be used, and examples thereof include a vacuum injection method and a liquid crystal dropping method.
In the vacuum injection method, for example, a liquid crystal cell is prepared in advance using a color filter and a counter substrate, and the liquid crystal is heated to obtain an isotropic liquid, and the liquid crystal is applied to the liquid crystal cell using the capillary effect. The liquid crystal layer can be formed by injecting in this state and sealing with an adhesive. Thereafter, the sealed liquid crystal can be aligned by slowly cooling the liquid crystal cell to room temperature.
In the liquid crystal dropping method, for example, a sealant is applied to the periphery of the color filter, the color filter is heated to a temperature at which the liquid crystal becomes isotropic, and the liquid crystal is dropped in an isotropic liquid state using a dispenser or the like. Then, the color filter and the counter substrate are overlapped with each other under a reduced pressure, and bonded through a sealant, whereby a liquid crystal layer can be formed. Thereafter, the sealed liquid crystal can be aligned by slowly cooling the liquid crystal cell to room temperature.

(4) Other Configurations The liquid crystal cell of the present invention is not particularly limited as long as it has the above-described color filter, liquid crystal driving element substrate, counter substrate, and liquid crystal layer, and other necessary configurations are appropriately selected. It is possible to select and add. Examples of such a configuration include an alignment film, a polarizing plate, and a light diffusion layer for a liquid crystal display device. Since these configurations can be the same as those used in a general liquid crystal display device, description thereof is omitted here.

3. Liquid crystal display device The liquid crystal display device of the present invention is not particularly limited as long as it has the above-described configurations. Moreover, since the liquid crystal display device of the present invention has the above-described configurations, it can have excellent color reproducibility. The color reproducibility of such a liquid crystal display device is not particularly limited as long as a desired color display can be performed according to the use of the liquid crystal display device and the like.

  The NTSC ratio of the liquid crystal display device is not particularly limited as long as a desired color display can be performed, but it is preferably 72% or more, particularly 73% or more, particularly 74% or more. When the chromaticity coordinates and NTSC ratio of each color of the liquid crystal display device are within the above ranges, high-definition and clear color display can be performed.

  The chromaticity coordinate of each color of the liquid crystal display device is not particularly limited as long as it is a value capable of performing a desired color display, but the red chromaticity coordinate is 0.650 <x <0.665 and 0.316. <Y <0.336, in particular 0.652 <x <0.665 and 0.318 <y <0.336, especially 0.653 <x <0.665 and 0.320 <y <0.336. It is preferable to become. Further, the chromaticity coordinates of green are 0.264 <x <0.292 and 0.577 <y <0.610, in particular 0.264 <x <0.291 and 0.580 <y <0.610, In particular, it is preferable that 0.264 <x <0.290 and 0.590 <y <0.610. Further, the blue chromaticity coordinates are 0.139 <x <0.154 and 0.044 <y <0.112, in particular, 0.145 <x <0.154 and 0.044 <y <0.085, It is particularly preferable that 0.145 <x <0.153 and 0.044 <y <0.081.

  The chromaticity coordinates of the liquid crystal display device are, for example, xy chromaticity and Y of each color light of red, green, and blue observed on the color filter side using a luminance meter (SR-3AR manufactured by Topcon Co., Ltd.). The value (brightness) can be measured. Further, the NTSC ratio can be calculated from the measurement coordinates described above.

  In addition, when the NTSC ratio of the liquid crystal display device indicates the above range, it is particularly preferable that the color coordinates of each color are within the above-described range. This is because higher-quality color display can be performed.

  Examples of the use of the liquid crystal display device of the present invention include a television, a personal computer, a monitor, and digital signage.

  Further, the manufacturing method of the liquid crystal display device of the present invention is not particularly limited, and can be the same as the manufacturing method of a general liquid crystal display device, and thus description thereof is omitted here.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

  Hereinafter, the present invention will be described with reference to examples.

[Examples 1-7]
(Production of the first light source)
The 1st light source was produced with the following procedures.
A near ultraviolet LED (emission peak wavelength: 405 nm) having a size of 300 μm square was prepared as a near ultraviolet light emitting element.
Next, each phosphor (red phosphor, green phosphor and blue phosphor) and silicone resin were mixed with the composition shown below using a mixing stirrer to prepare a phosphor layer composition. In addition, the composition of the following phosphor layer composition is obtained by adjusting the ratio so that the chromaticity coordinates of the first light source are x = 0.319 and y = 0.343.

<Composition of composition for phosphor layer>
・ Red phosphor ((La0.892Eu0.108) 2O2S) 7.5 parts by mass ・ Green phosphor ((Sr1.28Ba0.5Mg0.1Eu0.1Mn0.02) SiO4) 13.5 parts by mass ・ Blue phosphor (Sr0 .95Ca0.02Eu0.0098) 10 (PO4) 6-Cl2) 9 parts by mass / transparent resin (silicone resin) 70 parts by mass

  Next, the phosphor layer composition was dispersed for 8 hours using a three-roll mill equipped with a high alumina roll (first dispersion treatment). After the first dispersion treatment, the phosphor layer composition was defoamed at 5 mTorr for 10 minutes using a defoaming stirrer (first defoaming treatment). After the first defoaming treatment, the phosphor layer composition was dispersed under the same conditions as the first dispersion treatment (second dispersion treatment). After the second dispersion treatment, the phosphor layer composition was defoamed under the same conditions as the first defoaming treatment (second defoaming treatment). After the second defoaming treatment, the phosphor layer composition was dispersed under the same conditions as the first dispersion treatment (third dispersion treatment). After the third dispersion treatment, the phosphor layer composition had a viscosity of 5500 Pa · s. Next, the phosphor layer composition was applied so as to cover the near-ultraviolet LED and heat-treated at 135 ° C. to obtain a first light source having a size of 350 μm square.

(Preparation of the second light source)
A blue LED (emission peak wavelength: 445 nm) having a size of 300 μm square was prepared as a second light source.

(Production of backlight)
A light guide plate having a size of 300 mm square was prepared, and a backlight was obtained by arranging a first light source and a second light source in a pattern around the light guide plate. As for the number ratio of the first light source and the second light source, when the light emission peak of the near ultraviolet light emitting element of the first light source is 1, the light emission peak of the blue light emitting diode of the second light source is 0.68 (Example) 1), 0.85 (Example 2), 1.09 (Example 3), 1.41 (Example 4), 1.90 (Example 5), 2.69 (Example 6), and 4. It adjusted so that it might become 24 (Example 7).

[Comparative example]
A backlight was obtained by arranging a plurality of the light guide plates around the light guide plate using only the first light source.
(Evaluation)
Four color filters having a red colored layer, a green colored layer, and a blue colored layer were prepared as evaluation color filters. Table 1 shows the chromaticity coordinates of the colored layer in each color filter.

  When the backlights of Examples 1 to 7 and Comparative Example and the above-described color filter were combined, the chromaticity coordinates of light of each color of red, green, blue, and white, and the NTSC ratio were measured. The results are shown in Table 2.

  When the backlights of Examples 1 to 7 were used, the NTSC ratio of the liquid crystal display device could be as high as 72.0% or more, but when the backlights of the comparative examples were used, the liquid crystal display device The NTSC ratio was less than 72.0%, and it was difficult to make it sufficiently high.

DESCRIPTION OF SYMBOLS 1 ... 1st light source 2 ... 2nd light source 3 ... Light source 10 ... Backlight 11 ... Near ultraviolet light emitting element 12R ... Red fluorescent substance 12G ... Green fluorescent substance 13 ... Phosphor layer 20 ... Color filter 21 ... Opposite base material 22R ... Red Colored layer 22G ... Green colored layer 22B ... Blue colored layer 30 ... Liquid crystal cell 31 ... Liquid crystal drive element substrate 32 ... Liquid crystal layer

Claims (4)

A near-ultraviolet light-emitting element, and a first light source including a phosphor layer formed to cover the near-ultraviolet light-emitting element and containing a red phosphor and a green phosphor;
A second light source having a blue light emitting diode;
A backlight comprising a light source having   The backlight according to claim 1, wherein the backlight is an edge light type backlight. The backlight according to claim 1 or claim 2,
A color filter having a red colored layer, a green colored layer, and a blue colored layer, a liquid crystal driving element substrate having a liquid crystal driving element, a counter substrate, and the liquid crystal driving element substrate and the counter substrate disposed between A liquid crystal cell having a liquid crystal layer;
A liquid crystal display device comprising: The color filter has a chromaticity coordinate of the red colored layer of 0.650 <x <0.670 and 0.320 <y <0.345, and a chromaticity coordinate of the green colored layer of 0.265 <x <. 0.295, 0.585 <y <0.610, and the chromaticity coordinates of the blue colored layer are 0.130 <x <0.150 and 0.08 <y <0.140,
The backlight has an emission peak intensity of the blue light emitting diode of the second light source in the range of 0.65 to 2.75, where the intensity of the emission peak in the near ultraviolet light region of the first light source is 1. The liquid crystal display device according to claim 3, wherein the number ratio of the first light source and the second light source is adjusted.

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