JP5768614B2 - Liquid crystal display - Google Patents

Description

  The present invention relates to a liquid crystal display device using an LED as a backlight light source.

  Since the liquid crystal display device has characteristics such as low power consumption and small size and light weight, it is widely used for a monitor of a personal computer, a monitor of a portable information terminal device, and the like, and high color rendering and high luminance are required.

Conventionally, in a liquid crystal display device, a CCFL (cold cathode fluorescent lamp) light source has been used as a light source of a backlight.
In recent years, liquid crystal display devices have adopted white LED light sources instead of CCFL light sources from the viewpoints of low power consumption and expansion of a color reproduction region (see, for example, Patent Document 1).
Examples of the white LED light source include a combination of a blue LED, a red LED, and a green LED that generates white light, and a combination of a blue LED and a phosphor such as a YAG phosphor that generates white light.
Compared to the case where blue light, red LED, and green LED are combined to generate white light, the method of combining blue LED and phosphor can make the white LED light source cheaper and smaller.

International Publication No. 2010-103767

A liquid crystal display device using a blue LED-based white LED light source can achieve high color rendering by increasing the color temperature and widening the color reproduction range by increasing the color temperature, but to increase the color temperature. Conventionally, it has been difficult to produce an LED having an ideal emission spectrum, and to adjust the transmittance with a color filter.
In addition, a liquid crystal display device using a blue LED-based white LED light source can increase color rendering by increasing the color temperature, and can increase brightness by decreasing the color temperature. It was difficult to have both.

  The present invention has been accomplished in view of the above circumstances, and an object thereof is to provide a liquid crystal display device having high color rendering properties, and more preferably, a liquid crystal display device having both high color rendering properties and high luminance characteristics. The purpose is to provide.

In the present invention, a backlight member including a white LED light source combining a phosphor with a blue LED, a backlight side polarizing plate, a liquid crystal cell and an image display surface side polarizing plate,
A blue / green conversion layer that converts light in the 470 nm to 500 nm region included in the light source light into light in the 520 nm to 560 nm region at any position along the optical path from the white LED light source to the image display surface; A color conversion layer including a blue / red conversion layer that converts light in a 470 nm to 500 nm region included into light in a 570 nm to 650 nm region is provided;
The blue / green conversion layer and the blue / red conversion layer are color conversion layers arranged in alignment with the patterns of green pixels and red pixels of the color filter of the liquid crystal cell,
The blue / green conversion layer is 2,3,5,6-1H, 4H-tetrahydro-8-trifluoromethylquinolidino (9,9a, 1-gh) coumarin, 3- (2′-benzimidazolyl) Containing one or more color conversion materials selected from -7-N, N-diethylaminocoumarin, basic yellow 51, solvent yellow 11, and solvent yellow 116;
The blue / red conversion layer is a cyanine dye having a 4-dicyanomethylene-2-methyl-6- (p-dimethylaminostyryl) -4H-pyran skeleton, 1-ethyl-2- [4- (p-dimethyl). A liquid crystal display device comprising one or more color conversion materials selected from a pyridine-based dye having an aminophenyl) -1,3-butadienyl] -pyridium-perchlorate skeleton and an oxazine-based dye provide.
The emission spectrum of a blue LED-based white LED light source has a peak in the blue region, a broad due to the phosphor exists on the long wavelength side, and further, the blue region peak and the broad region in the range of 470 nm to 500 nm There is a transition area between. The present invention separates the peak of the blue region from the broad region by reducing the light (component) in the transition region (470 nm to 500 nm) included in the light source light from the blue LED-based white LED light source. Since the emission spectrum of the peak in the blue region is made sharper, the color purity can be improved and the color rendering can be improved.

  In the present invention, a backlight member including a white LED light source combining a phosphor with a blue LED, a backlight side polarizing plate, a liquid crystal cell and an image display surface side polarizing plate,
  A color conversion layer including a blue / green conversion layer that converts light in the 470 nm to 500 nm region included in the light source light into light in the 520 to 560 nm region at any position along the optical path from the white LED light source to the image display surface Is provided in a solid pattern that covers the entire cross section of the optical path,
  The blue / green conversion layer is 2,3,5,6-1H, 4H-tetrahydro-8-trifluoromethylquinolidino (9,9a, 1-gh) coumarin, 3- (2′-benzimidazolyl) A liquid crystal display device comprising one or more color conversion materials selected from -7-N, N-diethylaminocoumarin, basic yellow 51, solvent yellow 11, and solvent yellow 116 is provided.

  As one embodiment of the present invention, there is provided a liquid crystal display device in which the color conversion layer is provided at a position other than between the backlight side polarizing plate and the image display surface side polarizing plate.

  As one embodiment of the present invention, there is provided a liquid crystal display device in which the color conversion layers arranged in the pattern are provided on the light exit surface of the backlight member.

As one embodiment of the present invention, the backlight member is a backlight member including a light guide plate and a white LED light source, and the light guide plate is 2 , 3, 5 , 6-1H, 4H-tetrahydro-8-. Selected from trifluoromethylquinolidino (9,9a, 1-gh) coumarin, 3- (2′-benzimidazolyl) -7-N, N-diethylaminocoumarin, basic yellow 51, solvent yellow 11, and solvent yellow 116 There is provided a liquid crystal display device having a blue / green conversion layer provided in a solid coating pattern so as to cover the entire cross section of the optical path containing one or more kinds of color conversion materials .

  As one embodiment of the present invention, there is provided a liquid crystal display device in which the color conversion layer is provided at a position closer to the image display surface than the image display surface side polarizing plate.

According to the present invention, it is possible to provide a liquid crystal display device having high color rendering properties by sharpening the peak of the blue region.
Further, in a preferred embodiment of the present invention, by converting the color of light of 470 nm to 500 nm, the peak of the blue region is made sharper, and at the same time, the color-converted light is utilized as light of other colors. Since the luminance is improved, a liquid crystal display device having both high color rendering and high luminance characteristics can be provided.

It is a figure explaining the liquid crystal display device of this invention. It is a figure explaining the liquid crystal display device of this invention. It is a figure explaining the liquid crystal display device of this invention.

The present invention is a liquid crystal display device comprising a backlight member including a white LED light source combining a phosphor with a blue LED, a backlight side polarizing plate, a liquid crystal cell, and an image display surface side polarizing plate,
A liquid crystal display device characterized in that a layer for reducing light (components) in the region of 470 nm to 500 nm contained in the light source light is provided at any position along the optical path from the white LED light source to the image display surface. I will provide a.
Hereinafter, the configuration and embodiments of the present invention will be described in detail. Although the present invention will be described in detail with reference to the drawings and examples, the present invention is not limited to these drawings and examples.

FIG. 1 is a schematic diagram (schematic cross-sectional view) showing an example (reference numeral 101) of the liquid crystal display device of the present invention. The liquid crystal display device 101 includes a backlight member 1, a backlight side polarizing plate 2, a liquid crystal cell 3, and an image display surface side polarizing plate 4 from the backlight side (light source side) to the image display surface side (viewer side). Are arranged in order, and the color conversion layer 5 is provided between the backlight member 1 and the backlight side polarizing plate 2.
In FIG. 1, the backlight member 1 is an edge light type surface light source, and the light guide plate 1b has a wedge shape in which the thickness increases from one side edge side toward the opposite side edge, and the thickness of the light guide plate 1b. The white LED light source 1a based on the blue LED is arranged on the end face of the side edge portion having a large size, and the reflectors 1c and 1d are arranged on the back side of the light guide plate, the thin end face, and the back side of the white LED light source. Yes.
As the color conversion layer 5, a blue / green conversion layer that converts light of a blue region wavelength into light of a green region wavelength is provided, and the conversion layer 5 directly covers the entire light emitting surface of the backlight member 1. Yes. Therefore, in this example, a solid pattern color conversion layer is provided so as to cover the entire cross section of the optical path from the white LED light source to the image display surface. In this example, the color conversion layer 5 is directly laminated on the light exit surface of the backlight member. However, as a modification, a color conversion sheet having the color conversion layer formed on the base film is used as the light exit surface of the backlight member. May be fixed in parallel with a gap from each other.
The liquid crystal cell 3 has a configuration in which a liquid crystal layer 3c is sandwiched between a driving substrate 3a and a color filter 3b and a side edge is sealed with a sealing material 3d. The backlight side polarizing plate 2 and the image display surface side polarizing plate 4 are arranged so that the liquid crystal cell 3 is sandwiched from the front and the back of the optical path, and the polarization axes of the two polarizing plates intersect.

FIG. 2 is a schematic view showing another example (reference numeral 102) of the liquid crystal display device of the present invention. The liquid crystal display device 102 has almost the same configuration as the liquid crystal display device 101 described above, but the color conversion layer 5 is further provided on the image display surface side than the image display surface side polarizing plate 4.
In FIG. 2, the color conversion layer 5 is an independent sheet form in which the color conversion layer is formed on the base film 5 s, and is arranged in parallel with an interval on the image display surface side of the image display surface side polarizing plate 4. ing. Although not apparent from FIG. 2, the color conversion layer 5 of the liquid crystal display device 102 includes a blue / green conversion layer that converts light in the blue region wavelength into light in the green region wavelength, and light in the blue region wavelength in the red region wavelength. It has a blue / red conversion layer that converts light, and these color conversion layers are arranged so as to match the arrangement pattern of green pixels and red pixels of the color filter 3b of the liquid crystal cell. That is, the blue / green conversion layer is provided in a pattern in alignment with the green pixel pattern of the color filter 3b, and the blue / red conversion layer is provided in pattern in alignment with the red pixel pattern of the color filter 3b. Yes.

FIG. 3 is a schematic view showing another example (reference numeral 103) of the liquid crystal display device of the present invention. The liquid crystal display device 103 has almost the same configuration as the liquid crystal display device 101 described above, but includes a color conversion material in the light guide plate 1b, and the light guide plate also functions as a color conversion layer.
In FIG. 3, blue / green conversion is used as the color conversion material, which converts light in the blue region wavelength into light in the green region wavelength. Therefore, in this example, a solid pattern color conversion layer is provided so as to cover the entire cross section of the optical path from the white LED light source to the image display surface.

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

(Backlight member)
The backlight member in the present invention diffuses the light emitted from the white light source, the light guide plate that converts spot light or line light emitted from the white LED light source into surface light, and the light that is disposed on the light guide plate and irradiated from the light guide plate. An optical sheet or the like that collects light, and a reflective sheet that is disposed below the light guide plate and reflects light traveling in the lower direction of the light guide plate toward the liquid crystal cell. The backlight member is disposed on the non-viewing side of the liquid crystal cell and emits light from the back side of the liquid crystal cell.
The optical sheet or the like may include a diffusion sheet that diffuses light, a condensing sheet that condenses light, and a protective sheet for protecting the condensing sheet.

(White LED light source)
As an LED light source used in the present invention, an LED light source (B-RG method) that generates white light by combining a blue LED and a red / green phosphor (RG phosphor), and a blue LED and an yttrium / aluminum / garnet phosphor An LED light source (B-YAG method) that generates white light in combination with (YAG phosphor) is preferred.
The RG phosphor may be any phosphor that absorbs blue light and emits red fluorescence and green fluorescence. For example, a conventionally known RG phosphor described in JP-A-2003-141905 can be used. .
The YAG phosphor may be any phosphor that absorbs blue light and emits green fluorescence. For example, a conventionally known YAG phosphor described in JP-A-2008-218486 can be used.

  The white LED light source may be disposed on a surface (end surface) other than the front side and the back side of the light guide plate (side light type surface light source), or may be disposed on the back side of the light guide plate (direct type surface light source). Among the side light type surface light sources, the edge light type surface light source in which the white LED light source is disposed only on one side surface of the light guide plate is preferable from the viewpoint of possible miniaturization.

(Light guide plate)
A conventionally well-known thermoplastic resin etc. can be used for a light-guide plate. Examples of the thermoplastic resin include acrylic resin, polycarbonate resin, polystyrene resin, and polyester resin. These resins may be used alone or in combination of two or more.

(Polarizer)
The backlight side polarizing plate and the image display surface side polarizing plate are members having a function of allowing only linearly polarized light in a specific vibration direction (polarization axis) to pass therethrough. Usually, the backlight side polarizing plate and the image display surface side polarizing plate are arranged so that their polarization axes are orthogonal to each other. Of the non-polarized light emitted from the backlight member, only linearly polarized light in a specific vibration direction passes through the backlight side polarizing plate, exits, and enters the liquid crystal cell. Next, a part of the polarized light incident on the liquid crystal cell becomes linearly polarized light whose polarization axis (vibration direction) is changed by 90 ° or −90 ° while passing through the liquid crystal cell, and is emitted, and is polarized on the image display surface side polarizing plate. Is incident on. Then, only linearly polarized light whose polarization axis (vibration direction) is changed by 90 ° or −90 ° while passing through the liquid crystal cell passes through the image display surface side polarizing plate and is emitted as image display light.
As the polarizing plate, a polarizing plate used in a conventionally known liquid crystal display device can be used. The polarizing plate may have an aspect constituted only by a polarizer having the polarization characteristics as described above or an aspect in which a protective film is provided only on one surface side of the polarizer, but usually, a protective film / polarizer / Like the protective film, it has a configuration in which a polarizer is sandwiched between protective films.

(Liquid crystal cell)
The liquid crystal cell used in the present invention has the same configuration as the liquid crystal cell of a conventional liquid crystal display device, and generally includes a drive base, a liquid crystal layer, and a color filter.
In the liquid crystal cell, for example, a color filter and a driving substrate such as a thin film transistor (TFT) substrate are opposed to each other to provide a gap of about 1 to 10 μm, and a liquid crystal compound is filled in the gap to fill the liquid crystal layer. And the periphery thereof is sealed with a sealing material. A liquid crystal alignment film for aligning liquid crystals is provided on the inner surface side of the electrode substrate facing the color filter.

The color filter has a configuration in which, for example, red (R) green (G) blue (B) pixels (colored layers) are arranged in a predetermined two-dimensional pattern, and each pixel is partitioned by a black matrix (BM) layer. Have.
A driving method of the liquid crystal display device is not particularly limited, and a driving method used in a general liquid crystal display device can be employed. As such a driving method, in addition to the above-described TFT method, for example, a TN (Twisted Nematic) method, an IPS (In-Plane Switching) method, an OCB (Optically Compensated Bend) method, and an MVA (Multi-Dominant Vertical Alignment) The system etc. can be mentioned. In the present invention, any of these methods can be preferably used.
As the liquid crystal compound of the liquid crystal layer, various liquid crystals having different dielectric anisotropy and mixtures thereof can be used depending on the driving method of the liquid crystal display device.

(Light reducing layer)
In the present invention, the layer that reduces light (components) in the region of 470 nm to 500 nm means that when light having a certain wavelength spectrum is incident from one side of the layer that reduces the light and is emitted from the opposite side, Compared with the ratio of the component of 470 nm-500 nm area | region contained, it has a function in which the ratio of the component of 470 nm-500 nm area | region contained in an emitted light becomes small.
Examples of the layer that reduces the light include a light-absorbing material layer that selectively absorbs light in the 470 nm to 500 nm region, and a color conversion layer that selectively converts light in the 470 nm to 500 nm region to light of other wavelengths. Is mentioned. Here, “selectively absorb or convert” means that the proportion of components in the 470 nm to 500 nm region included in the emitted light is smaller than the proportion of components in the 470 nm to 500 nm region included in the incident light. This means that light outside the 470 nm to 500 nm region may be reduced as long as the function can be exhibited, and is limited to a typical meaning that light outside the 470 nm to 500 nm region is not reduced at all. It is not a thing.
Accordingly, the light reducing layer allows not only the components in the 470 nm to 500 nm region but also the components other than the 470 nm to 500 nm region to be reduced. However, from the viewpoint of achieving the object of the present invention, the light reducing layer reduces the light. The layer reduces the proportion of components in the 470 nm to 500 nm region included in the emitted light to 50% or less compared to the proportion of components in the 470 nm to 500 nm region included in the incident light, and other visible regions It is preferable to reduce the light in a wavelength selective manner so that the ratio of the components in the wavelength region is 60% or more.
The light reduction rate due to the light reducing layer can be measured by comparing the absorption wavelengths of incident light and emitted light using visible-ultraviolet spectroscopy (UV-VIS). Specifically, when the reference light including the wavelength region to be measured is 100, the ratio of the transmission spectrum when the reference light is transmitted through the layer that reduces light can be calculated by comparison.

Among the color conversion layers, those that convert light in the 470 nm to 500 nm region into light of other wavelengths in the visible region sharpen the peak in the blue region by reducing the light in the 470 to 500 nm region included in the light source light. In addition to realizing high color rendering of image display, the light in the above-mentioned 470 nm to 500 nm region included in the light source light can be selectively converted to visible light of another wavelength and used, so that high brightness of the image display is also realized. This is preferable because it is possible.
The conversion efficiency of the color conversion layer is that blue / green conversion efficiency for converting blue to green is 10% or more, blue / red conversion efficiency for converting blue to red is 20% or more, and total conversion efficiency is 30% or more. Is preferred.
As the method for measuring the conversion efficiency by the color conversion layer, visible / ultraviolet spectroscopy (UV-VIS) can be used in the same manner as the method for measuring the light reduction rate by the light reducing layer. Specifically, the reference light including the 470 nm to 500 nm region is used as the reference light, the wavelength spectrum of the reference light is set to 100, and the ratio of the transmission spectrum when the reference light is transmitted through the color conversion layer is compared. Calculate the decrease rate of light in the 500 nm region, calculate the increase rate of light in the wavelength region where you want to check the conversion rate in the same way as the decrease rate, use the decrease rate of light in the 470 nm to 500 nm region as the denominator, and convert the conversion rate to The conversion efficiency is obtained when the increase rate of light in the desired wavelength region is used as the numerator.

  As a method of forming a layer that reduces light, a coating composition is prepared by mixing a material that reduces light in the region of 470 nm to 500 nm, such as a light absorbing material and a color conversion material, with a binder and other materials as necessary. A method of forming a layer that reduces light by preparing and applying this to a special support such as a resin substrate or a support made of a member included in a liquid crystal display device such as a polarizing plate, or the above light A method of forming a layer composed only of the light-reducing material by applying a material to be reduced to the support, or a film (including a sheet having a relatively high self-supporting property) from a mixture of the light-reducing material and a binder. And a material for reducing the light in a resin for forming a light guide plate of a backlight member, for example, a method for using the layer as a layer for reducing light and a member included in a liquid crystal display device It was mixed, and a method of using a member obtained by forming a layer that reduces the light.

As the binder, for example, a thermoplastic resin, an energy ray curable resin such as ultraviolet curing or ionizing radiation curing, a thermosetting resin, or the like can be used.
For example, a polymer of a monomer having an ethylenic double bond typified by an acrylic polymer, for example, ethylene-vinyl acetate copolymer, ethylene-vinyl chloride copolymer, ethylene vinyl copolymer, polystyrene, acrylonitrile-styrene A copolymer, ABS resin, polymethacrylic acid resin, ethylene methacrylic acid resin, polyvinyl chloride resin, chlorinated vinyl chloride, polyvinyl alcohol, etc. can be mentioned.
Examples of the alkali-soluble binder include (meth) acrylic acid, dimer of acrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid, vinyl acetic acid, and ethylenic acids having acid groups such as these acid anhydrides. Mention may be made of polymers of monomers having a double bond.
As the acrylic polymer, for example, an acrylic polymer having an epoxy group such as a glycidyl group described in JP 2010-2746 A is preferably used.
In addition, cellulose acetate propionate, cellulose acetate butyrate, nylon 6, nylon 66, nylon 12, polyethylene terephthalate, polybutylene terephthalate, polycarbonate, polyvinyl acetal, polyether ether ketone, polyether sulfone, polyphenylene sulfide, Examples include polyarylate, polyvinyl butyral, epoxy resin, phenoxy resin, polyimide resin, polyamideimide resin, polyamic acid resin, polyetherimide resin, phenol resin, urea resin, and the like.
Polymerizable polyfunctional or monofunctional monomers such as methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, sec-butyl (meth) acrylate, isobutyl (meth) ) Acrylate, tert-butyl (meth) acrylate, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, n-decyl (meth) acrylate , 2-hydroxyethyl methacrylate, benzyl methacrylate, styrene, α-methylstyrene, N-vinyl-2-pyrrolidone, glycidyl (meth) acrylate, and the like.
In the present invention, (meth) acryl means either acryl or methacryl, and (meth) acrylate means either acrylate or methacrylate.
As the resin substrate, a transparent resin substrate conventionally used for optical members can be used. In addition, as an optical member that directly forms a layer that reduces light, for example, a light guide plate, an antireflection film, an alignment film, a polarizing film, a polarizing layer protective film, a retardation film, a viewing angle improving film, a brightness improving film, etc. Can be mentioned.

The layer that reduces light may be formed in a predetermined pattern in alignment with pixels of each color of the liquid crystal display device. When the light reducing layer is formed in a predetermined pattern, it may be formed in accordance with a conventionally known pixel forming method such as a photolithography method. For example, the light reducing material and a binder resin are used. If necessary, a photosensitive resin composition is prepared by mixing with a solvent, a diluent, a monomer, or the like, and an appropriate additive, and the photosensitive resin composition is applied to the surface (region) to be coated by a spin coating method. It is formed by repeating each color by applying, exposing with UV light (pattern exposure) through a photomask, and washing (developing) the unexposed part with a solvent or an alkaline aqueous solution such as an aqueous potassium hydroxide solution. can do.
As another method, the ink composition containing the light reducing material may be selectively attached to the application target surface (region) for each pixel pattern by an ink jet method or a printing method. . In this case, it is also possible to use a non-photosensitive ink composition.

  Examples of the light-absorbing material include pyrogallol red (PR) / Mo complex, “NK5705” manufactured by Hayashibara Biochemical Laboratories, “Atto 475 NHHoster” manufactured by Fluka, and the like.

As the color conversion material, for example, a color conversion fluorescent dye such as a blue / green conversion fluorescent dye that converts blue to green or a blue / red conversion fluorescent dye that converts blue to red can be used.
Blue / green conversion fluorescent dyes include 2,3,5,6-1H, 4H-tetrahydro-8-trifluoromethylquinolidino (9,9a, 1-gh) coumarin, 3- (2′-benzothiazolyl) Coumarin dyes such as -7-diethylaminocoumarin or 3- (2′-benzimidazolyl) -7-N, N-diethylaminocoumarin, coumarin dyes such as basic yellow 51, solvent yellow 11 or solvent yellow 116 And naphthalimide dyes.
Examples of the blue / red conversion fluorescent dye include cyanine dyes having 4-dicyanomethylene-2-methyl-6- (p-dimethylaminostyryl) -4H-pyran skeleton, 1-ethyl-2- [4- (p- Examples thereof include pyridine dyes having a dimethylaminophenyl) -1,3-butadienyl] -pyridium-perchlorate skeleton, rhodamine dyes such as rhodamine B or rhodamine 6G, or oxazine dyes.
As the color conversion fluorescent dye, fluorescent dyes can be selected and used from various dyes such as direct dyes, acid dyes, basic dyes, or disperse dyes. You may use only 1 type or may use 2 or more types together.

  Examples of binder resins for dissolving or dispersing these color conversion fluorescent dyes include polymethyl methacrylate resin, polyacrylate resin, polycarbonate resin, polyvinyl alcohol resin, polyvinyl pyrrolidone resin, hydroxyethyl cellulose resin, carboxymethyl cellulose resin, polyvinyl chloride resin, melamine Examples thereof include transparent resins such as resins, phenol resins, alkyd resins, epoxy resins, polyurethane resins, polyester resins, maleic acid resins, and polyamide resins. Alternatively, as the resin, an ionizing radiation curable resin having a reactive vinyl group such as acrylate, methacrylate, polyvinyl cinnamate, or cyclized rubber (actually, an electron beam curable resin or an ultraviolet curable resin) Resin, often the latter).

  The ratio of the binder resin and the color conversion fluorescent dye in the color conversion layer is, for example, about resin / color conversion fluorescent dye = 100 / 0.5 to 100/5 (mass basis). The thickness of the color conversion layer is preferably about 5 μm to 20 μm.

The arrangement position of the light reducing layer in the optical path direction may be provided at any position in the optical path from the white LED light source to the image display surface.
When a color conversion layer is used as a light reducing layer, light leakage occurs during black display on the image display surface due to a change in the polarization direction of polarized light due to the color conversion of polarized light that has passed through the backlight-side polarizing plate. From the viewpoint of prevention, it is more preferable to provide at a position other than between the backlight side polarizing plate and the image display surface side polarizing plate.

When the light reducing layer is provided in a solid pattern for all color pixels such as RGB included in the color filter, a blue / green conversion layer is provided from the viewpoint of balance between luminance and color. preferable.
When a blue / green conversion layer and a blue / red conversion layer are used in combination, the blue / green conversion layer is aligned with the green pixel, and the blue / red conversion layer is aligned with the red pixel. Provide a color conversion layer on the blue pixel, or align the blue / green conversion layer with the blue and green pixels and align the blue / red conversion layer with the red pixels It is more preferable from the viewpoint of balance between luminance and color.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to these examples.

Example 1
Cyanine dye having 4-dicyanomethylene-2-methyl-6- (p-dimethylaminostyryl) -4H-pyran skeleton as blue / red conversion fluorescent dye, (2, 3, 5, 5) as blue / green conversion fluorescent dye 6-1H, 4H-tetrahydro-8-trifluoromethylquinolidino (9,9a, 1-gh) coumarin was used.
The binder resin for dissolving the color conversion fluorescent dye was prepared as follows.
In a polymerization tank, 63 parts by mass of methyl methacrylate (MMA), 12 parts by mass of acrylic acid (AA), 6 parts by mass of 2-hydroxyethyl methacrylate (HEMA) and 88 parts by mass of diethylene glycol dimethyl ether (DMDG) as a solvent were charged. After stirring and dissolving, 7 parts by mass of 2,2′-azobisisobutyronitrile (AIBN) as a polymerization initiator was added and dissolved uniformly. Then, it stirred at 85 degreeC under nitrogen stream for 2 hours, and also was made to react at 100 degreeC for 1 hour. Further, 7 parts by mass of glycidyl methacrylate (GMA), 0.4 parts by mass of triethylamine and 0.2 parts by mass of hydroquinone were added to the obtained solution, and the mixture was stirred at 100 ° C. for 5 hours to obtain a copolymer resin solution (solid content of 50 %).
Further, the following materials were mixed and stirred at room temperature to obtain a curable resin composition as a binder.
The copolymer resin solution (solid content 50%): 16 parts by mass Dipentaerythritol pentaacrylate (trade name SR399 manufactured by Sartomer): 24 parts by mass Orthocresol novolac type epoxy resin (Product made by Yuka Shell Epoxy Co., Ltd.) Name Epicoat 180S70): 4 parts by mass 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one (trade name Irgacure 907 manufactured by Ciba Specialty Chemicals Co., Ltd.): 4 parts by mass Part Diethylene glycol dimethyl ether: 52 parts by mass Next, the color conversion fluorescent dye and the binder resin are mixed for each color so that the ratio of the resin and the color conversion fluorescent dye is binder resin / color conversion fluorescent dye = 70/30 (mass basis). Mixed. Further, as a solvent, propylene glycol monomethyl ether acetate (PGMEA) / 3-methoxybutyl acetate (MBA) was mixed and used at a ratio of 80/20 (mass basis), and 25 parts by mass with respect to 1 part by mass of the conversion dye. did. Megafuck was used as an additive. The mixture is applied and formed for each color by aligning with the green pixel pattern and the red pixel pattern of the color filter on the outgoing surface of the backlight member by a photolithography method. A blue / green conversion layer that converts light of 470 nm to 500 nm, and a blue / red conversion layer that converts light of 470 nm to 500 nm into light of 570 nm to 650 nm, the blue / green conversion layer and the blue / red conversion layer comprising: Color conversion layers arranged in alignment with the patterns of green pixels and red pixels of the color filter were prepared. The thickness of the color conversion layer was set to 1.5 to 1.7 μm.
The color conversion layer is inserted above the light guide plate of the liquid crystal display device using the edge light type B-YAG white LED light source, and the light is reduced in the blue wavelength region (470 nm to 500 nm) using visible / ultraviolet spectroscopy. And the rate of increase of light in the green wavelength range (520 nm to 560 nm) and the red wavelength range (570 nm to 650 nm), and the green wavelength range (520 nm to 560 nm) and the red wavelength range relative to the decrease rate of light in the blue wavelength range Each conversion efficiency was calculated from the increase rate of light at (570 nm to 650 nm), and the total conversion efficiency was further calculated. The measurement results are shown in Table 1.
In addition, WHITE luminance Y and NTSC (National Television System Committee) ratio were measured. The measurement results are shown in Table 2.

(Comparative Example 1)
The WHITE luminance Y and the NTSC ratio were measured using the same liquid crystal display device as in Example 1 except that the layers for reducing light (blue / green conversion layer and blue / red conversion layer) were not included. The measurement results are shown in Table 2.

(Measurement result)
As shown in Table 1, the light reduction rate in the blue wavelength range of Example 1 is 78.4%, and the light conversion efficiency in the green wavelength range and the red wavelength range with respect to the light reduction rate in the blue wavelength range is 10.5% and 38.8%, respectively, and the total conversion efficiency is 49.3%. It can be seen that light in the blue wavelength range is reduced and converted into the green wavelength range and the red wavelength range. .
As shown in Table 2, the WHITE luminance Y is improved from 33.3 to 33.9 and the NTSC ratio is improved from 62% to 68% in comparison with the comparative example 1, and the high luminance and high It can be seen that it has been rendered.

DESCRIPTION OF SYMBOLS 1 Backlight member 1a Light source 1b Light guide plate 1c Reflective material 1d Reflective material 2 Backlight side polarizing plate 3 Liquid crystal cell 3a Driving base 3b Color filter 3c Liquid crystal layer 3d Sealing material 4 Image display surface side polarizing plate 5 Color conversion layer 5s Base Material film 101 Liquid crystal display device 102 Liquid crystal display device 103 Liquid crystal display device

Claims (6)

A backlight member including a white LED light source combining a phosphor with a blue LED, a backlight side polarizing plate, a liquid crystal cell, and an image display surface side polarizing plate,
A blue / green conversion layer that converts light in the 470 nm to 500 nm region included in the light source light into light in the 520 nm to 560 nm region at any position along the optical path from the white LED light source to the image display surface; A color conversion layer including a blue / red conversion layer that converts light in a 470 nm to 500 nm region included into light in a 570 nm to 650 nm region is provided;
The blue / green conversion layer and the blue / red conversion layer are color conversion layers arranged in alignment with the patterns of green pixels and red pixels of the color filter of the liquid crystal cell,
The blue / green conversion layer is 2,3,5,6-1H, 4H-tetrahydro-8-trifluoromethylquinolidino (9,9a, 1-gh) coumarin, 3- (2′-benzimidazolyl) Containing one or more color conversion materials selected from -7-N, N-diethylaminocoumarin, basic yellow 51, solvent yellow 11, and solvent yellow 116;
The blue / red conversion layer is a cyanine dye having a 4-dicyanomethylene-2-methyl-6- (p-dimethylaminostyryl) -4H-pyran skeleton, 1-ethyl-2- [4- (p-dimethyl). A liquid crystal display device comprising one or more color conversion materials selected from a pyridine-based dye having an aminophenyl) -1,3-butadienyl] -pyridium-perchlorate skeleton and an oxazine-based dye . A backlight member including a white LED light source combining a phosphor with a blue LED, a backlight side polarizing plate, a liquid crystal cell, and an image display surface side polarizing plate,
A color conversion layer including a blue / green conversion layer that converts light in the 470 nm to 500 nm region included in the light source light into light in the 520 to 560 nm region at any position along the optical path from the white LED light source to the image display surface Is provided in a solid pattern that covers the entire cross section of the optical path ,
The blue / green conversion layer is 2,3,5,6-1H, 4H-tetrahydro-8-trifluoromethylquinolidino (9,9a, 1-gh) coumarin, 3- (2′-benzimidazolyl) A liquid crystal display device comprising one or more color conversion materials selected from -7-N, N-diethylaminocoumarin, basic yellow 51, solvent yellow 11, and solvent yellow 116 . The color conversion layer is provided from the backlight side polarizing plate in a position other than the image display surface side polarizing plates, a liquid crystal display device according to claim 1 or 2. The liquid crystal display device according to claim 1 , wherein the color conversion layer is provided on a light exit surface of a backlight member. The backlight member is a backlight member including a light guide plate and a white LED light source, and 2,3,5,6-1H, 4H-tetrahydro-8-trifluoromethylquinolidino (9,9a, 1-gh) Containing one or more color conversion materials selected from coumarin, 3- (2′-benzimidazolyl) -7-N, N-diethylaminocoumarin, basic yellow 51, solvent yellow 11, and solvent yellow 116 The liquid crystal display device according to claim 2 , further comprising a blue / green conversion layer provided in a solid pattern so as to cover the entire cross section of the optical path .   The liquid crystal display device according to claim 3, wherein the color conversion layer is provided at a position closer to the image display surface than the image display surface side polarizing plate.

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