JP2019203911A - Display device and polarizing member - Google Patents

Abstract

To provide a display device which offers improved image display quality by reducing ionic impurities in an alignment film and a liquid crystal layer.SOLUTION: A display device comprises a polarizing layer 28 including a film with a polarizer, and a wavelength conversion layer 30, where the polarizer and the wavelength conversion layer 30 are bonded together by an adhesive layer 36 containing an ultraviolet-curable adhesive.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a display device and a polarizing member.

  A general liquid crystal display device is a non-light-emitting display device, in which light from a backlight using a white LED or the like as a light source is light-modulated for each pixel by a liquid crystal layer, and red (R) and green (G). , Blue (B) is transmitted through each color filter layer to perform color display. The white LED has features such as good luminous efficiency and long life. On the other hand, the white LED has a large light loss due to a decrease in luminous efficiency of the phosphor due to heat generation (so-called temperature quenching). Also, because the color filter layer separates the light from the white LED into red, green and blue, only about 1/3 of the backlight is actually used, and the light utilization efficiency of the entire liquid crystal display device Is low.

  Further, a liquid crystal display device of a type that uses an ultraviolet light source as a backlight and emits phosphor layers of red, green, and blue colors using the ultraviolet light source as excitation light is disclosed (Patent Document 1). In addition, a blue LED is used as a backlight, and red and green phosphor layers are emitted by using the blue light output from the blue LED to obtain red and green light, and the blue light from the blue LED is used as it is. A liquid crystal display device that transmits blue light and displays it is disclosed (Patent Document 2).

  A pair of substrates between which the liquid crystal layer is sandwiched; a light emitting diode that emits light having a peak wavelength in the range of 380 nm to 420 nm disposed on the back surface on one side of the pair of substrates; and the other side of the pair of substrates. And a polarizing plate formed on the other side of the pair of substrates on the side opposite to the liquid crystal layer of the polarizing plate, for each unit pixel, absorbs light having a peak wavelength in the range of 380 nm to 420 nm and has a predetermined color. Disclosed is a liquid crystal display device that includes a subpixel including a phosphor layer that emits light, and a filter layer that reflects or absorbs light having a wavelength of 420 nm or less on a surface opposite to the liquid crystal layer of the phosphor layer. (Patent Document 3).

Japanese Patent Laid-Open No. 08-036158 JP 2003-005182 A JP 2010-250259 A

  By the way, in a display device using liquid crystal, an in-cell type in which a polarizing layer is formed between a liquid crystal portion and a color filter layer may be employed. In the in-cell type display device, a polarizer is formed on a substrate on which a color filter is formed, an alignment film is formed thereon, and a step of bonding to a TFT substrate (thin film transistor) is performed while forming a liquid crystal layer. . In the conventional manufacturing method, an adhesive is used when the polarizing plate is formed on the substrate. However, a general adhesive contains a large amount of impurities, and there is a high possibility that impurities are mixed into the alignment film and the liquid crystal layer. Become. If ionic impurities are present in the alignment film or the liquid crystal layer, the image display quality may be significantly deteriorated.

  One aspect of the present invention includes a polarizing layer including a film having a polarizer and a wavelength conversion layer, and the polarizer and the wavelength conversion layer, or the polarizer and the film are UV-curable. The display device is characterized by being bonded by an adhesive layer containing an adhesive.

  Here, the ultraviolet curable adhesive is preferably cured in response to light in a wavelength region of 380 nm or less.

  The adhesive layer preferably includes a thermosetting adhesive in addition to the ultraviolet curable adhesive.

  Another aspect of the present invention includes a polarizing layer including a film having a polarizer and a wavelength conversion layer, and the polarizer and the wavelength conversion layer, or the polarizer and the film are formed by a plasma bonding layer. The display device is characterized by being bonded.

  Here, the film having the polarizer is preferably a stretched polyvinyl alcohol film dyed with a dichroic dye.

  The polarizer preferably includes a reflective polarizer. At this time, the reflective polarizer is preferably formed of a cholesteric liquid crystal layer. The reflective polarizer is preferably composed of a wire grid polarizing layer.

  Moreover, it is suitable to provide the backlight which irradiates light with respect to the said wavelength conversion layer.

Another aspect of the present invention includes a polarizing film having a polarizer, an adhesive layer containing an ultraviolet curable adhesive, a protective film covering the surface of the polarizing film, and a release film covering the back surface of the polarizing film. An adhesive layer provided between the polarizing film and the release film;
And the adhesive layer includes a UV curable adhesive.

  Here, it is preferable that the adhesive layer is not cured by ultraviolet rays.

  The ultraviolet curable adhesive is preferably cured in response to light in a wavelength region of 380 nm or less.

  The protective film preferably absorbs at least part of light in a wavelength region of 460 nm or less.

  The release film preferably absorbs at least part of light in a wavelength region of 460 nm or less.

  The adhesive layer preferably has a viscosity of 50 mPa · s to 250 mPa · s.

  ADVANTAGE OF THE INVENTION According to this invention, the ionic impurity in alignment film or a liquid crystal layer can be reduced, and the display apparatus which improved the display quality of the image, and the polarizing member which can be used for it can be provided.

It is a figure which shows the structure of the liquid crystal display device in 1st Embodiment. It is a figure which shows the structure of the polarizing layer of the liquid crystal display device in 1st Embodiment. It is a figure which shows the structure of the polarizing layer of the liquid crystal display device in 2nd Embodiment. It is a figure which shows the structure of the other example of the polarizing layer of the liquid crystal display device in 2nd Embodiment. It is a figure which shows the structure of the polarizing layer of the liquid crystal display device in 3rd Embodiment. It is a figure which shows the structure of the polarizing layer of the liquid crystal display device in 4th Embodiment. It is a figure which shows the structure of the polarizing member in 5th Embodiment.

<First Embodiment>
As shown in the schematic cross-sectional view of FIG. 1, the liquid crystal display device 100 according to the first embodiment includes a polarizing plate 10, an optical compensation layer 12, a TFT substrate 14, an interlayer insulating film 16, a display electrode 18, and a second interlayer. The insulating film 16a, the common electrode 26, the alignment film 20, the liquid crystal layer 22, the alignment film 24, the polarizing layer 28, the wavelength conversion layer 30, the counter substrate 32, and the backlight 34 are configured.

  The liquid crystal display device 100 functions as a device that displays light by receiving light from the backlight 34 and outputting the light wavelength-converted by the wavelength conversion layer 30 from the polarizing plate 10 side, as indicated by arrows. In addition, the liquid crystal display device 100 can positively utilize the external light incident from the polarizing plate 10 side, and can output the wavelength of the external light by the wavelength conversion layer 30. FIG. 1 is a schematic diagram, and the size and thickness of each component do not reflect actual values.

  In this embodiment, an active matrix liquid crystal display device is described as an example of the liquid crystal display device 100. However, the scope of application of the present invention is not limited to this, and a liquid crystal display of another mode such as a simple matrix type is used. It is also applicable to the device.

  Further, the liquid crystal display device 100 is configured as an IPS (lateral electric field switching) type liquid crystal display device, but the scope of application of the present invention is not limited to this. For example, the present invention can be applied to other types of liquid crystal display devices such as a configuration of a VA (vertical alignment) type liquid crystal display device.

  The TFT substrate 14 is configured by arranging TFTs for each pixel on the substrate. The substrate is a transparent substrate such as glass. The substrate is used to mechanically support the liquid crystal display device 100 and to display an image by transmitting light. The substrate may be a flexible substrate made of a resin such as an epoxy resin, a polyimide resin, an acrylic resin, or a polycarbonate resin.

In FIG. 1, two TFTs are shown. A gate electrode 14a connected to the gate line is disposed at a lower portion (on the substrate) substantially in the middle of the TFT. A gate insulating film 14b is formed covering the gate electrode 14a, and a semiconductor layer 14c is formed covering the gate insulating film 14b. The gate insulating film 14b is formed of an insulator such as SiO ₂ . The semiconductor layer 14c is formed of amorphous silicon or polysilicon, and a portion directly above the gate electrode 14a is a channel region having almost no impurities, and both sides are a source region and a drain region to which conductivity is imparted by impurity doping. Is done. A contact hole is formed on the drain region of the TFT, and a metal (for example, aluminum) drain electrode is disposed (electrically connected) thereon, and a contact hole is formed on the source region, in which the metal is formed. A source electrode (for example, aluminum) is disposed (electrically connected). The drain electrode is connected to a data line to which a data voltage is supplied.

  A polarizing plate 10 is formed on the surface of the TFT substrate 14 on which the TFT is not formed. A polarizing plate 10 is formed so as to cover the surface of the substrate of the TFT substrate 14. The polarizing plate 10 preferably includes a dye-type polarizer in which a PVA (polyvinyl alcohol) resin is dyed with an iodine material or a dichroic dye.

  A display electrode 18 is provided on the surface of the TFT substrate 14 on which the TFT is formed via an interlayer insulating film 16. The display electrode 18 is an individual electrode separated for each pixel, and is a transparent electrode made of, for example, ITO (indium tin oxide). The display electrode 18 is connected to a source electrode formed on the TFT substrate 14.

  A second interlayer insulating film 16 a is formed so as to cover the display electrode 18. On the second interlayer insulating film 16a, a striped common electrode 26 unique to the IPS system is formed. Further, an alignment film 20 that covers the common electrode 26 and aligns the liquid crystal is formed. The alignment film 20 is made of a resin material such as polyimide. For example, the alignment film 20 is printed by printing a 5 wt% solution of N-methyl-2-pyrrolidinone in which polyimide resin is dissolved on the second interlayer insulating film 16a and the common electrode 26, and is cured by heating at about 160 to 280 ° C. Then, it can be formed by orientation treatment by rubbing with a rubbing cloth.

  Next, the configuration and manufacturing method on the counter substrate 32 side will be described. The counter substrate 32 is a transparent substrate such as glass. The counter substrate 32 is used to mechanically support the liquid crystal display device 100 and transmit light from the backlight 34 to enter the wavelength conversion layer 30 or the like. The counter substrate 32 may be a flexible substrate made of a resin such as an epoxy resin, a polyimide resin, an acrylic resin, or a polycarbonate resin.

  A wavelength conversion layer 30 is formed on the counter substrate 32. The wavelength conversion layer 30 is arranged in a matrix in the in-plane direction of the counter substrate 32 for each pixel. As the wavelength conversion layer 30, any one of a phosphor, a quantum dot, and a quantum rod that receives light from a backlight 34 described later and emits light in a specific wavelength region can be applied.

  The phosphor is preferably made of a material that emits one of red (R), green (G), and blue (B) for each pixel. Eu-activated sulfide-based red phosphor is used for the red phosphor, Eu-activated sulfide-based green phosphor is used for the green phosphor, and Eu-activated phosphate-based blue phosphor is used for the blue phosphor. it can. The wavelength conversion layer 30 may include a single phosphor or a plurality of phosphors depending on the color to be displayed.

  For example, when two types of phosphors that absorb blue light and yellow light by absorbing light from the backlight 34 in the range of 380 nm to 460 nm and outside light are included, pseudo white light is obtained. be able to. Similarly, white light can be obtained when three kinds of phosphors emitting red light, green light, and blue light are included. Further, by appropriately selecting and using single or plural phosphors that absorb light from the backlight 34 having a peak wavelength in the range of 380 nm to 460 nm and external light and emit light of any color, any A liquid crystal display device capable of emitting colored light is obtained.

  In addition, for example, when two types of phosphors that absorb light from the backlight 34 in the ultraviolet wavelength range of 380 nm or less and emit blue light and yellow light that emit light in a desired wavelength region are included. Can obtain pseudo white light. Similarly, white light can be obtained when three kinds of phosphors emitting red light, green light, and blue light are included. Further, light of any color is emitted by appropriately selecting and using single or plural phosphors that absorb light from the backlight 34 having a peak wavelength in the range of 380 nm or less and emit light of any color. A liquid crystal display device can be obtained.

  The wavelength conversion layer 30 can also be realized by a quantum dot structure in which a plurality of semiconductor materials having different characteristics are periodically arranged three-dimensionally or a quantum rod that is periodically arranged two-dimensionally. Quantum dots and quantum rods function as a material having a desired band gap by repeatedly arranging semiconductor materials having different band gaps with a period of nm order. It can be used as the wavelength conversion layer 30 that emits light in a wavelength region corresponding to the gap. Specifically, a quantum dot structure having a characteristic of absorbing light in the wavelength region of the output light of the backlight 34 and emitting any one of red (R), green (G), and blue (B) A quantum rod structure is formed.

  For example, the quantum dot may have a structure in which the central core (core) is formed of cadmium selenide (CdSe) and the outside thereof is covered with a zinc sulfide (ZnS) coating layer (shell). The emission color can be controlled by changing the diameter. For example, when emitting red (R), the diameter may be 8.3 nm, when emitting green (G), the diameter may be 3 nm, and when emitting blue (B), the diameter may be further reduced. Further, as the central core material, indium phosphide (InP), indium copper sulfide (CuInS2), carbon, graphene, or the like may be used.

  The wavelength conversion layer 30 is a phosphor, quantum dot, or quantum rod that emits red (R), green (G), and blue (B), and is formed and arranged by patterning at a location corresponding to the display electrode. Display is possible. In the patterning process, a phosphor material, a quantum dot material, or a quantum rod material that emits red (R), green (G), and blue (B) is dispersed in a photosensitive polymer, and this dispersion liquid is dispersed by a coater. It is realized by coating, forming, exposing and developing on the top. A black matrix may be formed between each color in order to prevent color mixing between display pixels.

  A polarizing layer 28 is formed on the wavelength conversion layer 30. The polarizing layer 28 preferably includes a polarizer obtained by dyeing a PVA (polyvinyl alcohol) resin with a dichroic dye. In the in-cell type display device, the thickness of the polarizing layer 28 is preferably 30 μm or less, and preferably 12 μm or less, more preferably 3 μm from the viewpoint of thinning the display device. Here, the polarizer is usually a film that is dyed and then stretched by a dry method or a wet method. Moreover, when a PVA film is a thin layer, in order to improve the handleability of a film, you may use what formed PVA resin and the support body film integrally. For example, a PVA resin is formed on a support film by a casting method and directly dyed and stretched, or a mixed solution of PVA resin and dichroic dye is formed on a support film by a casting method and then stretched. A film formed using a method (original deposition method) or the like may be used.

  When a dichroic dye such as an azo compound, an anthraquinone compound or a tetrazine dye is used as the dichroic dye, the durability of the optical characteristics under high temperature conditions and high temperature and high humidity conditions is excellent. Hue adjustment is easy.

  The dichroic dye is preferably an azo compound dye from the viewpoint of optical properties and durability. I. Direct Yellow 12, C.I. I. Direct Yellow 28, C.I. I. Direct Yellow 44, C.I. I. Direct Orange 26, C.I. I. Direct Orange 39, C.I. I. Direct Orange 107, C.I. I. Direct Red 2, C.I. I. Direct Red 31, C.I. I. Examples include Direct Red 79, dyes described in JP-A No. 2003-215338, and dyes described in WO 2007/138980.

  Examples of commercially available dyes include Kayafect Violet P Liquid (manufactured by Nippon Kayaku Co., Ltd.), Kayafect Yellow Y, Kayafect Orange G, Kayafect Blue KW, and Kayafect Blue Liquid 400.

  Furthermore, a dichroic dye optimized for the hue of the achromatic polarizing plate described in WO2015 / 186661, WO2014 / 162634 may be used.

  At this time, it is preferable to obtain a neutral gray hue by blending two or more of these dyes so as to supplement the polarization characteristics at each wavelength in the visible range and dyeing them on PVA.

It is particularly preferable from the viewpoint of durability that the azo compound includes a water-soluble disazo compound represented by the chemical formula (1) or the copper complex salt compound.
Here, X represents a hydrogen atom, a methyl group, a methoxy group or an ethoxy group, and Y represents a methoxy group or an ethoxy group. R ₁ represents a hydrogen atom or a methyl group, and R ₂ is substituted with a hydrogen atom, a methyl group, a —C ₂ H ₄ OH group, a substituted or unsubstituted phenyl group, a phenyl group substituted with a carboxy group, or a sulfone group. Represents a phenyl group.

  A commercially available compound may be used, and the compound can be produced by a known production method, for example, a production method described in JP-A-59-145225.

Furthermore, it is preferable that the water-soluble compound represented by the chemical formula (2) or a copper complex salt compound thereof is included as the azo compound.
Here, A represents a phenyl group or naphthyl group substituted with a methyl group, and R represents an amino group, a methylamino group, an ethylamino group, or a phenylamino group.

  A commercially available compound may be used, and it can be produced by a known production method, for example, a production method described in JP-A-3-12606.

  A normal polarizer is an iodine polarizer formed of a material dyed with iodine and an iodine compound on a resin. However, iodine and iodine compounds are vulnerable to heat and are altered by heating at about 100 ° C. On the other hand, a polarizer using a dye (dichroic dye) is relatively resistant to heat and can be prevented from being altered by heating at about 130 ° C. Therefore, the polarizing layer 28 can be formed between the counter substrate 32 and the alignment film 24 without being affected by the film formation temperature when forming the alignment film 24 and the common electrode 26 described later. That is, when a dichroic dye is used as the dichroic dye, the durability of optical characteristics under high temperature conditions and high temperature and high humidity conditions is superior to iodine. Also, the color change during molding is less than that of iodine. Therefore, the hue can be easily adjusted, and the yellowness can be lowered as compared with the case where iodine is used as the dichroic dye.

  FIG. 2 is an enlarged cross-sectional view showing an enlarged region in the vicinity of the interface between the polarizing layer 28 and the wavelength conversion layer 30 indicated by a broken-line circle in FIG. As shown in FIG. 2, the polarizing layer 28 and the wavelength conversion layer 30 are bonded using an adhesive layer 36. Here, the adhesive layer 36 includes an ultraviolet curable adhesive. The ultraviolet curable adhesive is preferably an adhesive that cures in response to light in a wavelength region of 380 nm or less.

  The ultraviolet curable adhesive has a lower content of impurities that adversely affect the alignment films 20 and 24 and the liquid crystal layer 22 than other adhesives such as a general thermosetting adhesive, and should be used. Therefore, it is possible to suppress the deterioration of the display quality of the liquid crystal display device 100. The adhesive layer 36 may contain an adhesive other than the ultraviolet curable adhesive, for example, a thermosetting adhesive. By including a thermosetting adhesive, for example, it can be preliminarily cured (semi-cured) by irradiation with ultraviolet rays, and further completely cured by heat curing, thereby allowing precise bonding. Alternatively, a mode in which heat is applied first to be temporarily cured and then completely cured by ultraviolet irradiation is also possible. In this case, in particular, in the fifth embodiment described later, the viscosity and the layer shape of the adhesive layer can be easily controlled by temporarily curing the adhesive layer.

  The ultraviolet curable adhesive may be a mixture of a (meth) acrylic compound and a radical photopolymerization initiator, a mixture of an epoxy compound and a cationic photopolymerization initiator, or the like. Further, a cationic polymerizable epoxy compound and a radical polymerizable (meth) acrylic compound may be used in combination, and a photo cationic polymerization initiator and a photo radical polymerization initiator may be used in combination as an initiator. As a commercially available ultraviolet curable adhesive, for example, Aronix (registered trademark) UCX series manufactured by Toa Gosei Co., Ltd. can be used.

  In addition, in order to improve adhesiveness with the polarizing layer 28 and the wavelength conversion layer 30, you may perform surface treatments, such as a corona treatment, a plasma treatment, an ultraviolet irradiation, and a primer application process, to each bonding surface.

  In addition, it is preferable to use a solvent-free ultraviolet curable adhesive as the ultraviolet curable adhesive. In the case of the solvent system, there is a problem that the surface of the substrate is eroded and the adhesive force is lowered. On the other hand, the use of a solvent-free adhesive can suppress damage to the polarizing layer. In the case of an ultraviolet curable adhesive, a composition in which a plurality of monomers having an acryloyl group or an epoxy group is mixed can be cured and adhered by irradiating with ultraviolet rays in the presence of a photopolymerization initiator. An ultraviolet curable adhesive is preferable in that it is cured in a short time and has high productivity.

  Solventless UV curable adhesives include (meth) acrylate adhesives, ene / thiol adhesives, unsaturated polyester adhesives that use photo radical polymerization reactions, and epoxy adhesives. And an adhesive using a photocationic polymerization reaction such as an adhesive, an oxetane adhesive, an epoxy / oxetane adhesive, and a vinyl ether adhesive. These may be used alone or in combination. In particular, a (meth) acrylate adhesive is preferable from the viewpoint of good transparency and weather resistance. The (meth) acrylate adhesive contains a monomer or oligomer having one or more (meth) acryloyl groups in the molecule and a photopolymerization initiator as essential components. The (meth) acrylate-based adhesive may further contain an additive or the like as necessary. Examples of the oligomer having one or more (meth) acryloyl groups in the molecule include epoxy (meth) acrylate, polyester (meth) acrylate, and urethane (meth) acrylate, and urethane (meth) acrylate is particularly preferable.

  When adjusting the viscosity of the ultraviolet curable adhesive, various solvents that sufficiently dissolve the adhesive may be used. However, it is preferable to use a reactive diluent, such as a monofunctional acrylic monomer, in order to avoid the problem of eroding the surface of the substrate and lowering the adhesive strength. Examples of monofunctional acrylic monomers include isooctyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, and methoxytriethylene glycol (meth) acrylate. , (Meth) acrylate, 2-ethylhexyl carbitol (meth) acrylate, ethoxyethoxyethyl (meth) acrylate, tricyclodecane (meth) acrylate, dicyclopentenyl (meth) acrylate, isobornyl ( (Meth) acrylate, adamantyl (meth) acrylate, benzyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, 2-hydroxyethyl (Meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, N- (meth) acryloyloxyethyl hexahydrophthalimide, ω- Examples thereof include carboxypolycaprolactone (meth) acrylate, monohydroxyethyl phthalate (meth) acrylate, and (meth) acrylic acid dimer.

  The ultraviolet curable adhesive is cured by irradiation with ultraviolet rays. Various ultraviolet rays can be used. Although the ultraviolet light source is not particularly limited, for example, sunlight, low-pressure mercury lamp, medium-pressure mercury lamp, high-pressure mercury lamp, ultra-high pressure mercury lamp, metal halide lamp, etc. can be used. Mercury lamps and metal halide lamps are preferred.

  The adhesive layer 36 preferably has a viscosity of 50 mPa · s to 250 mPa · s. By setting the viscosity in such a range, the bonding process can be easily performed in the processing step for joining the polarizing layer 28 and the wavelength conversion layer 30, and the processing accuracy can be improved by avoiding the deviation during the bonding. .

  In addition, what is necessary is just to select the application | coating method of an adhesive agent suitably with the viscosity and target thickness of an adhesive agent. Examples of the coating method include a method using a reverse coater, a gravure coater (direct, reverse or offset), a bar reverse coater, a roll coater, a die coater, a bar coater, or a rod coater.

  The adhesive layer 36 is preferably about several μm thick. The adhesive layer 36 is, for example, 3 μm.

  An alignment film 24 is formed on the polarizing layer 28. The alignment film 24 is made of a resin material such as polyimide. The alignment film 24 is formed by, for example, printing a 5 wt% solution of N-methyl-2-pyrrolidinone in which a polyimide resin is dissolved on the polarizing layer 28 and curing it by heating at about 110 to 280 ° C., and then using a rubbing cloth. By rubbing, it can be formed by orientation treatment.

  The alignment films 20 and 24 are alignment films that are aligned in a direction nearly parallel to the counter substrate 32, and are subjected to alignment treatment by rubbing or photo-alignment. The alignment direction is aligned so that the alignment films 20 and 24 are parallel to each other.

  At this time, a photo-alignment film can also be used. If the photo-alignment film is used, a low-temperature process of 130 ° C. or less is facilitated. Further, in the photo-alignment, in order to improve the viewing angle characteristics, the pixel may be divided by changing the alignment direction in an area within one pixel by changing the light irradiation direction. The photo-alignment is more preferable because the pretilt angle is eliminated and the viewing angle characteristics are improved.

  Further, the liquid crystal layer 22 is sealed between the alignment film 20 and the alignment film 24 so that the alignment film 20 and the alignment film 24 face each other. A spacer (not shown) is inserted between the alignment film 20 and the alignment film 24, liquid crystal is injected between the alignment film 20 and the alignment film 24, and the periphery is sealed with a sealing material (not shown). Thus, the liquid crystal layer 22 is formed.

  The alignment of the liquid crystal layer 22 is controlled by the alignment film 20 and the alignment film 24, and the initial alignment state (when no electric field is applied) of the liquid crystal of the liquid crystal layer 22 is determined by the alignment film 20 and the alignment film 24. Then, by applying a voltage to the display electrode 18 and the common electrode 26, an electric field is generated in the liquid crystal, the orientation of the liquid crystal layer 22 is controlled, and the transmission / non-transmission of light is controlled.

  The liquid crystal layer 22 has a positive or negative dielectric anisotropy. When the dielectric constant is positive, there are advantages such as good response characteristics at low temperatures and less influence of moisture. Further, when the dielectric anisotropy is negative, the liquid crystal layer 22 is controlled almost completely parallel to the counter substrate 32 when a voltage is applied, so that the transmittance can be improved.

  In the IPS type liquid crystal display device 100, an electric field is generated in the in-plane direction of the liquid crystal layer 22 by applying a voltage to the common electrode 26, and the liquid crystal molecules laid horizontally are rotated in the horizontal direction to emit light. To control. At this time, since the vertical tilt of the liquid crystal molecules does not occur, it is possible to reduce the luminance change and the color change due to the viewing angle.

  The backlight 34 includes a light source that outputs light. The light source is preferably an LED, for example. The wavelength of the light output from the backlight 34 is preferably light in a wavelength region that can be effectively used for wavelength conversion in the wavelength conversion layer 30. For example, the backlight 34 is preferably a light source that outputs light in a wavelength region having a peak wavelength of 380 nm to 460 nm or a light source that outputs light in a wavelength region of 380 nm or less.

  According to the liquid crystal display device 100, the light use efficiency can be increased by converting the wavelength of the light from the backlight 34 in the wavelength conversion layer 30 and using it. Accordingly, energy efficiency in the liquid crystal display device 100 can be improved, and the liquid crystal display device 100 with low power consumption can be realized. In addition, by applying a semiconductor layer having a quantum dot structure as the wavelength conversion layer 30, the power consumption can be further reduced as compared with the case of using a phosphor.

  Further, by adopting an in-cell structure in which the polarizing layer 28 is formed between the counter substrate 32 and the liquid crystal layer 22, the wavelength conversion layer 30 can also be provided between the counter substrate 32 and the liquid crystal layer 22. The distance between the illuminant, the display electrode 18 and the TFT substrate 14 can be made shorter than before. For example, the counter substrate 32 has a thickness of about 500 μm, and the wavelength conversion layer 30 is formed on the display electrode 18 by the thickness of the counter substrate 32 as compared with the case where the polarizing layer 28 is formed between the counter substrate 32 and the backlight 34. You can get closer. As a result, it is possible to reduce the margin of the distance between the pixels in order to avoid color mixing between the pixels. Therefore, the high-resolution liquid crystal display device 100 can be provided.

<Second Embodiment>
In the liquid crystal display device 100 according to the first embodiment, the polarizing layer 28 includes a dye-type polarizer dyed with a dichroic dye. However, the present invention is not limited to this.

  FIG. 3 is an enlarged cross-sectional view showing the configuration of the alignment film 24, the polarizing layer 28, and the wavelength conversion layer 30 in the second embodiment. In the present embodiment, the polarizing layer 28 includes a reflective polarizer.

  The reflective polarizer includes a wire grid polarizer 30a. A wire grid polarizer (WGP) is an array of parallel wires arranged on the surface of a transparent substrate such as glass. Usually, a wire grid polarizer is a single periodic array of wires on a substrate. When the period of the wire is greater than approximately half of the wavelength of light, the grid behaves as a diffraction grating. When the period of the wiring is less than about half of the wavelength of light, the grid behaves as a polarizer. The wire grid polarizer 30a is a polarizer in which metal nanowires are arranged in a grid. As a material which comprises a wire grid, metals, such as aluminum, silver, copper, chromium, titanium, nickel, tungsten, and iron, or these alloys can be used, for example. For example, the wire grid polarizer 30a may have a configuration in which aluminum having a height of several tens to several hundreds of nm is arranged in a thin line at a pitch of about 100 nm. The wire grid polarizer 30a transmits light that vibrates in a direction orthogonal to the longitudinal direction of the grid, and reflects light that vibrates in a direction parallel to the longitudinal direction of the grid.

  The polarizing layer 28 can be formed, for example, by forming an aluminum layer having a thickness of 20 nm on the wavelength conversion layer 30 and processing it into a grid shape having a pitch of 140 nm using a photolithography technique or the like. The polarizing layer 28 can also be formed using a nanoimprint technique. Specifically, a negative resist pattern is formed on the substrate by nanoimprinting, and unnecessary portions of the resist are removed by ashing. Thereafter, Al is formed by CVD, and the resist can be removed by a method called lift-off. . Furthermore, the wire grid polarizer 30a can also be formed using a metal self-assembly technique (see Macromolecular Chemistry and Physics, Vol. 217, No. 6 (2016)). For example, the above-described protective layer such as PMMA may be formed on the wavelength conversion layer, and the polarizing layer 28 may be formed thereon.

  The reflective polarizer is not limited to a wire grid polarizer. As shown in FIG. 4, the polarizing layer 28 may include a reflective polarizer including a cholesteric liquid crystal layer 30b.

  The cholesteric liquid crystal layer 30b can be formed by stacking a plurality of cholesteric liquid crystal layers having different chiral pitches. A cholesteric liquid crystal is a liquid crystal in which the optical axis is twisted at a constant pitch, and shows a reflection color called selective reflection according to the twist pitch. A cholesteric liquid crystal can be prepared by adding an additive called a chiral agent to a nematic liquid crystal to give optical rotation. At this time, a desired chiral pitch can be obtained by adjusting the addition rate of the chiral agent.

  For example, the first cholesteric liquid crystal having a chiral pitch of 428 nm to 490 nm, the second cholesteric liquid crystal having a chiral pitch of 520 nm to 580 nm, and the third cholesteric liquid crystal having a chiral pitch of 600 nm to 660 nm. A plurality of layers may be stacked. As a specific example, the first cholesteric liquid crystal 26e-1 may have a chiral pitch of 460 nm, the second cholesteric liquid crystal 26e-2 may have a chiral pitch of 550 nm, and the third cholesteric liquid crystal 26e-3 may have a chiral pitch of 630 nm.

  A cholesteric liquid crystal layer 30b having a plurality of different chiral pitches in one layer may be used. This can be produced by adjusting the temperature profile when cured with a thermosetting polymer cholesteric liquid crystal.

  Also in the present embodiment, the wavelength conversion layer 30 and the polarizing layer 28 are bonded by the adhesive layer 36. Also in this case, the adhesive layer 36 includes an ultraviolet curable adhesive. The ultraviolet curable adhesive is preferably an adhesive that cures in response to light in a wavelength region of 380 nm or less. The adhesive layer 36 preferably has a thickness of about several μm. The adhesive layer 36 is, for example, 3 μm. As the ultraviolet curable adhesive, the same one as in the first embodiment can be applied.

  The ultraviolet curable adhesive has a lower content of impurities that adversely affect the alignment films 20 and 24 and the liquid crystal layer 22 than other adhesives such as a general thermosetting adhesive, and should be used. Therefore, it is possible to suppress the deterioration of the display quality of the liquid crystal display device 100. The adhesive layer 36 also functions as a flattening layer for flattening the unevenness of the wire grid polarizer 30a. The adhesive layer 36 may contain an adhesive other than the ultraviolet curable adhesive, for example, a thermosetting adhesive.

<Third Embodiment>
In the liquid crystal display device 100 according to the first embodiment, the polarization layer 28 and the wavelength conversion layer 30 including a dye-type polarizer dyed with a dichroic dye using the adhesive layer 36 including an ultraviolet curable adhesive. However, the polarizing layer 28 and the wavelength conversion layer 30 may be bonded by plasma bonding.

  In the plasma bonding, a surface modification step by plasma discharge, a step of adsorbing a medium material such as water vapor on the surface to form a chemical bond between the surfaces (formation of the plasma modification layer 38), and heat bonding are performed. This is a technique for joining two materials by sequentially performing the steps, and is described in a known document (WO2011 / 10738).

  Even in the case of the interface between the polarizing layer 28 containing PVA and the wavelength conversion layer 30, the interface between the polarizing layer 28 and the wavelength conversion layer 30 can be altered and bonded to each other by applying plasma bonding. Thereby, as shown in the enlarged sectional view of FIG. 5, the polarizing layer 28 and the wavelength conversion layer 30 are bonded via the plasma modification layer 38.

  In the plasma bonding, it is preferable that after forming the plasma modified layer 38, heat is applied to press the materials together. Therefore, when the polarizing layer 28 is a PVA film that has been stretched in a thin film shape, the polarizing layer 28 may be deformed such as contraction depending on the heating temperature. Therefore, the heating temperature is preferably 70 ° C. or higher and 100 ° C. or lower, more preferably 70 ° C. or higher and 80 ° C. or lower. Moreover, when the PVA film of the polarizing layer 28 is dyed with a dichroic dye, it is possible to suppress deterioration of optical characteristics due to heat treatment.

  By bonding the polarizing layer 28 and the wavelength conversion layer 30 by using the plasma modification layer 38, the alignment films 20 and 24 and the liquid crystal can be compared with the case where an adhesive such as a general thermosetting adhesive is used. Impurities that adversely affect the layer 22 can be reduced. Accordingly, it is possible to suppress a decrease in display quality of the liquid crystal display device 100.

<Fourth embodiment>
In the liquid crystal display device 100 according to the second embodiment, the polarizing layer 28 including the wire grid polarizer 30a and the wavelength conversion layer 30 are bonded using the bonding layer 36 including an ultraviolet curable adhesive. The polarizing layer 28 and the wavelength conversion layer 30 may be bonded.

  As described above, the plasma bonding is a technique in which the interface between the polarizing layer 28 and the wavelength conversion layer 30 is subjected to plasma treatment on the interface between the polarizing layer 28 containing PVA and the wavelength conversion layer 30 to be bonded to each other. . As a result, as shown in the enlarged sectional view of FIG. 6, the polarizing layer 28 including the wire grid polarizer 30 a and the wavelength conversion layer 30 are bonded via the plasma modification layer 38.

  By bonding the polarizing layer 28 and the wavelength conversion layer 30 by using the plasma modification layer 38, the alignment films 20 and 24 and the liquid crystal can be compared with the case where an adhesive such as a general thermosetting adhesive is used. Impurities that adversely affect the layer 22 can be reduced. Accordingly, it is possible to suppress a decrease in display quality of the liquid crystal display device 100.

<Fifth embodiment>
In the first to fourth embodiments, the aspect of the display device has been described. In the fifth embodiment, a polarizing member 200 including a polarizer used to configure the polarizing layer 28 will be described.

  As shown in FIG. 7, the polarizing member 200 in the present embodiment includes a polarizing film 40, a protective film 42, a release film 44, and an adhesive layer 46.

  The polarizing film 40 preferably includes a dye-type polarizer obtained by dyeing a PVA (polyvinyl alcohol) resin with a dichroic dye. The polarizing film 40 can be formed in the same manner as the polarizing layer 28 in the first embodiment.

  The protective film 42 is a film for protecting one surface of the polarizing film 40. The protective film 42 is usually composed of a resin film and an adhesive layer laminated thereon. The resin film is composed of a thermoplastic resin, for example, a polyolefin resin such as polyethylene resin or polypropylene resin; a polyester resin such as polyethylene terephthalate or polyethylene naphthalate; a polycarbonate resin; a (meth) acrylic resin, or the like. Can do. The resin film is preferably made of polyethylene terephthalate (PET) from the viewpoint of preventing dents and imprints during processing. The pressure-sensitive adhesive layer is used for attaching the protective film 42 to the polarizing film 40. Since the protective film 42 is peeled off when the polarizing member 200 is used, the adhesive is preferably made of a material that does not remain on the surface of the polarizing film 40 when the protective film 42 is peeled off. In addition, generally the thickness of the protective film 42 is 40-100 micrometers, and when it is less than 40 micrometers, the protection effect with respect to a dent or a stamp is not acquired, and it becomes difficult to peel from the polarizing film 40.

  Note that the protective film 42 may have a layer that suppresses or reduces charge during peeling. Thereby, it can prevent that a member and a film closely_contact | adhere by static electricity, or attracting | sucking a foreign material.

  The release film 44 is a film for protecting the other surface of the polarizing film 40. The release film 44 is preferably composed of a resin film and a release layer. Examples of the resin film include polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, and polyolefins such as polypropylene. Among these, polyethylene terephthalate (PET) is preferable from the viewpoint of optical properties and quality, and biaxially stretched polyethylene terephthalate film is preferable because of excellent dimensional stability. Further, the release layer can be formed from, for example, a release layer forming composition, and the main component (resin) constituting the release layer forming composition is not particularly limited. Examples thereof include resins, alkyd resins, acrylic resins, and long-chain alkyl resins. Of these, silicone resins are preferred.

  The thickness of the release film 44 can be adjusted by the thickness of the resin film and the thickness of the release layer. In particular, the thickness of the resin film is dominant and can be adjusted by selecting a PET film having a target thickness. The thickness of the resin film is preferably 38 μm or more, and more preferably 50 μm or more. The upper limit of the film thickness of the resin film is not particularly limited, but is usually 200 μm or less, and may be, for example, 150 μm or less from the viewpoint of facilitating pulling when the release film 44 is peeled off. Preferably, it is 100 μm or less. The thickness (when dried) of the release layer is preferably 40 nm or more and 300 nm or less, more preferably 50 nm or more and 200 nm or less, and further preferably 80 nm or more and 150 nm or less. When the thickness of the release layer is less than 40 nm, the adhesion between the adhesive layer 46 and the release film 44 becomes strong, and the release film 44 is hardly peeled off. By setting the thickness of the release layer to 40 nm or more, it is possible to suppress variations in the peel force due to fluctuations in the coating amount. Moreover, the phenomenon (blocking) which closely_contact | adheres by the release films 44 which have a peeling layer can be suppressed because the thickness of a peeling layer shall be 300 nm or less.

  The adhesive layer 46 is a layer used for attaching the polarizing member 200 to another member when the polarizing member 200 is used. The adhesive layer 46 includes an ultraviolet curable adhesive. The ultraviolet curable adhesive is preferably an adhesive that cures in response to light in a wavelength region of 380 nm or less. As the ultraviolet curable adhesive, the same one as in the first embodiment can be applied.

  By including an ultraviolet curable adhesive in the adhesive layer 46, the influence of impurities on the alignment film and the liquid crystal layer when the polarizing member 200 is applied to the display device can be reduced, and the display quality of the display device can be reduced. The decrease can be suppressed. The adhesive layer 46 may include an adhesive other than the ultraviolet curable adhesive, for example, a thermosetting adhesive.

  The adhesive layer 46 may be applied to the surface of the polarizing film 40, and then the release layer of the release film 44 may be bonded to the adhesive layer 46, or may be applied to the surface of the release layer of the release film 44. The adhesive layer 46 may be applied, and then the polarizing film 40 may be bonded to the adhesive layer 46.

  The adhesive layer 46 preferably has a viscosity of 50 mPa · s to 250 mPa · s. By setting it as such a viscosity range, when applying the polarizing member 200 to a display apparatus, the process of bonding becomes easy, and the processing precision can be improved by avoiding a shift or the like at the time of bonding.

  The adhesive layer 46 is preferably about several μm thick. The adhesive layer 46 is, for example, 3 μm.

  In the present embodiment, it is preferable that the protective film 42 does not transmit light with a short wavelength of 460 nm or less, particularly light with a wavelength of 380 nm. It is preferable to have an ultraviolet absorption characteristic that absorbs light in a wavelength region of 380 nm or less. For example, light in a wavelength region of 380 nm or less may be absorbed by mixing a UV absorber in the protective film 42. Thereby, it is possible to prevent the adhesive layer 46 from being cured by the ultraviolet light included in the light incident from the protective film 42 side before the protective film 42 is peeled off when the polarizing member 200 is used.

  Further, it is preferable that the release film 44 does not transmit light having a short wavelength of 460 nm or less, particularly light of 380 nm. It is preferable to have an ultraviolet absorption characteristic that absorbs light in a wavelength region of 380 nm or less. For example, light in a wavelength region of 380 nm or less may be absorbed by mixing an ultraviolet absorber in the release film 44. Thereby, it is possible to prevent the adhesive layer 46 from being cured by ultraviolet light included in the light incident from the release film 44 side before the release film 44 is peeled off when the polarizing member 200 is used.

  It is preferable that the ultraviolet absorber is excellent in absorption performance of ultraviolet rays of 380 nm or less. Specifically, the light transmittance at 380 nm of the ultraviolet absorbing layer containing the ultraviolet absorber is 10% or less, preferably 5.0% or less, more preferably 3.0% or less, particularly preferably. Is preferably 1.0% or less. When the transmittance at 380 nm is 1.0% or less, ultraviolet light having a wavelength of 380 nm or less is almost completely absorbed, so that the adhesive layer can be more effectively prevented from being cured.

  Examples of the ultraviolet absorber include organic ultraviolet absorbers such as oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, and nickel complex compounds. These materials may be used alone or in combination. The blending ratio of the ultraviolet absorber varies depending on the material such as the resin film to be blended, but is preferably 0.1 wt% or more and 20 wt%, more preferably 0.5 wt% or more and 10 wt% or less. preferable. If it is less than 0.1% by weight, light of 380 nm or less cannot be completely absorbed. On the other hand, when the content exceeds 10% by weight, the ultraviolet absorbing ability is improved, but the ultraviolet absorbent may be easily transferred to the adhesive layer over time.

  DESCRIPTION OF SYMBOLS 10 Polarizing plate, 12 Optical compensation layer, 14 TFT substrate, 14a Gate electrode, 14b Gate insulating film, 14c Semiconductor layer, 16, 16a Interlayer insulating film, 18 Display electrode, 20 Alignment film, 22 Liquid crystal layer, 24 Alignment film, 26 Common electrode, 26e cholesteric liquid crystal, 28 polarizing layer, 30 wavelength conversion layer, 30a wire grid polarizer, 30b cholesteric liquid crystal layer, 32 counter substrate, 34 backlight, 36 adhesive layer, 38 plasma modified layer, 40 polarizing film, 42 Protective film, 44 release film, 46 adhesive layer, 100 liquid crystal display device, 200 polarizing member.

Claims (15)

A polarizing layer including a film having a polarizer, and a wavelength conversion layer,
The display device, wherein the polarizer and the wavelength conversion layer, or the polarizer and the film are bonded by an adhesive layer containing an ultraviolet curable adhesive. The display device according to claim 1,
The ultraviolet curable adhesive is cured in response to light in a wavelength region of 380 nm or less. The display device according to claim 1 or 2,
The display device according to claim 1, wherein the adhesive layer includes a thermosetting adhesive in addition to the ultraviolet curable adhesive. A polarizing layer including a film having a polarizer, and a wavelength conversion layer,
The display device, wherein the polarizer and the wavelength conversion layer, or the polarizer and the film are bonded by a plasma bonding layer. The display device according to any one of claims 1 to 4,
The display device, wherein the film having a polarizer is obtained by stretching a polyvinyl alcohol film dyed with a dichroic dye. A display device according to any one of claims 1 to 5,
The display device, wherein the polarizer includes a reflective polarizer. The display device according to claim 6,
The display device, wherein the reflective polarizer is made of a cholesteric liquid crystal layer. The display device according to claim 6,
The reflective polarizer comprises a wire grid polarizing layer. The display device according to any one of claims 1 to 8,
A display device comprising a backlight for irradiating light to the wavelength conversion layer. A polarizing film having a polarizer;
An adhesive layer containing an ultraviolet curable adhesive;
A protective film covering the surface of the polarizing film;
A release film covering the back surface of the polarizing film;
An adhesive layer provided between the polarizing film and the release film;
With
The polarizing member, wherein the adhesive layer includes an ultraviolet curable adhesive. The polarizing member according to claim 10,
The polarizing member, wherein the adhesive layer is not cured by ultraviolet rays. The polarizing member according to claim 10 or 11,
The polarizing member, wherein the ultraviolet curable adhesive is cured in response to light in a wavelength region of 380 nm or less. The polarizing member according to claim 11,
The said protective film absorbs at least one part of the light of a wavelength range below 460 nm, The polarizing member characterized by the above-mentioned. The polarizing member according to claim 11 or 12,
The said release film absorbs at least one part of the light of a wavelength range below 460 nm, The polarizing member characterized by the above-mentioned. The polarizing member according to any one of claims 10 to 13,
The polarizing member, wherein the adhesive layer has a viscosity of 50 mPa · s or more and 250 mPa · s or less.