JP5217392B2 - Diffuser, diffusion film, polarizing film, liquid crystal display device - Google Patents

Description

  The present invention relates to a diffuser, a diffusion film, a polarizing film, and a liquid crystal display device. In particular, the present invention relates to an on-vehicle liquid crystal display device, and also relates to a diffuser, a diffusion film and a polarizing film used in the liquid crystal display device.

  In recent years, a liquid crystal display (LCD) has been used in many applications such as a liquid crystal television, a personal computer monitor, a notebook PC, and an FA device. This is because the liquid crystal display device is a typical flat panel display and has characteristics of being light, thin, and low power consumption.

In particular, the need for an in-vehicle liquid crystal display device is increasing due to the fact that terrestrial digital broadcasting has come to be seen in the car due to the spread of terrestrial digital broadcasting and the spread of car navigation.
However, in-vehicle liquid crystal display devices are severely demanded for environment resistance such as heat resistance and cold resistance in addition to image display characteristics such as moving image display performance and light emission luminance, and few of them satisfy the specifications.

Liquid crystal display devices include reflective liquid crystal display devices and transmissive liquid crystal display devices depending on the difference in the light incident direction and the light emitting direction.
In addition, liquid crystal panels used in liquid crystal display devices have a TN (Twisted Nematic) type, a VA (Vertical Alignment) type, an IPS (In Plane Switching) type, an OCB (Optically Compensated Bend) type, depending on the molecular orientation of the liquid crystal. and so on.

The IPS liquid crystal panel is a system in which an electric field is applied in the direction of the glass substrate surface, and liquid crystal molecules are rotated in a plane parallel to the glass substrate. Since it is not necessary to form an electrode on one glass substrate, the aperture ratio can be increased and display performance can be improved. In the VA liquid crystal panel, when no voltage is applied, liquid crystal molecules are perpendicular to the glass substrate, and when a voltage is applied, the liquid crystal molecules are parallel to the glass substrate and transmit light. .
These IPS-type liquid crystal panels and VA-type liquid crystal panels are not so excellent in environmental resistance such as heat resistance and cold resistance. Therefore, in-vehicle liquid crystal display devices that are highly likely to be placed in a high-temperature and high-humidity environment. Not suitable.

  On the other hand, in a TN liquid crystal panel, liquid crystal molecules are twisted and arranged at 90 degrees about a direction perpendicular to the substrate. When a voltage is applied, the liquid crystal molecules are arranged in a vertical direction along the electric field and transmit light. The image is displayed by blocking or blocking. This TN type liquid crystal panel is excellent in environmental resistance such as heat resistance and cold resistance, and has excellent characteristics such as wide operating temperature range, high aperture ratio, stable production, and availability at low cost. Therefore, it is suitable for in-vehicle liquid crystal display devices and is most commonly used. However, there is a problem that the color of the display image changes or the display gradation deteriorates due to a difference in viewing angle of the display screen (hereinafter, viewing angle).

Since the mounting position of the in-vehicle liquid crystal display device is limited, most display images can be seen from an oblique direction with respect to the image display surface.
For example, a liquid crystal display device for car navigation applications is attached around the center of the dashboard. On the other hand, since the observer who sees the image is in the driver's seat or the passenger seat, the observer sees the display image from about 30 to 50 degrees in the horizontal direction with respect to the image display surface. The rear liquid crystal display device is installed between the passenger seat and the driver seat. Since the observer who sees the image is on the right side or the left side of the rear seat, the observer sees the display image from about 30 to 50 degrees in the horizontal direction with respect to the image display surface.

In addition, in the vehicle, an image of the in-vehicle liquid crystal display device is seen at a short distance. Therefore, the observation angle varies depending on the height of the observer, the seat position, and the like. For example, there may be a difference in observation angle up to about 20 degrees between an adult and a child.
For the above reasons, the color of the display image is changed or the display gradation is deteriorated due to the difference in the observation angle, which is a big problem for the in-vehicle liquid crystal display device.

For example, Patent Document 1 discloses a backlight unit (surface light source), a liquid crystal panel, and polarization so as not to change the color of a display image and not to deteriorate display gradation even if the observation angle is changed. A liquid crystal display device including a plate, a retardation film, and a light diffusion layer is disclosed. By providing this light diffusion layer, high contrast and wide field of view are possible.
Patent Document 2 discloses a liquid crystal display device including a backlight unit system, a liquid crystal cell, a polarizing plate, and a viewing angle widening layer. By providing this viewing angle widening layer, contrast is high and color reproducibility can be improved.

However, when the light diffusing layer, the viewing angle widening layer, or the like is provided, image blurring may occur or backscattered light noise of external light may occur, resulting in a display image becoming worse.
For example, when a diffusion film is installed in front of a TN type liquid crystal panel, there is a thickness of a glass substrate that the TN type liquid crystal panel has, a thickness of a polarizing film attached on the glass substrate of the TN type liquid crystal panel, and the like. The diffusion film cannot be adhered to the TN type liquid crystal layer that is the image display surface. Therefore, a diffuser is installed at a position away from the TN type liquid crystal layer, and the image observed from the observer on the front side of the TN type liquid crystal panel is blurred.
Further, when observed in a bright room, external light may be backscattered by the light diffusion layer or the viewing angle expansion layer to generate backscattered light noise, and the image may become whitish and difficult to see.

Furthermore, in a liquid crystal display device for in-vehicle use, the TN type liquid crystal display device is used because of environmental resistance such as heat resistance and cold resistance, although the display image is viewed at a considerably larger observation angle than usual. However, there is a problem that a good image cannot be seen because the color and gradation of the display image change depending on the viewing angle.
Japanese Patent Laid-Open No. 10-10513 JP 20044763 A

  The present invention provides a diffuser, a diffusion film, a polarizing film, and a liquid crystal display device that reduce a difference in color and gradation of a display image depending on an observation angle, suppress image blurring, and suppress backscattering noise of external light. The purpose is to get.

In order to achieve the above object, the present invention employs the following configuration. That is,
The diffuser of the present invention is used for a liquid crystal display device including a TN type liquid crystal panel, and is a diffuser disposed on the surface on the observer side of the TN type liquid crystal panel, and the diffuser is used as a forming material. The light scattering particles are dispersed, the refractive index difference Δn between the light scattering particles and the forming material is 0.12 or more and 0.23 or less , and the particle diameter of the light scattering particles is 0.4 μm or more and 0.00. 5 μm or less , the haze ratio of the diffuser is 42.2% or more and 49.1% or less , and incident light composed of parallel rays is incident from a direction perpendicular to the surface opposite to the observer of the diffuser. Then, 10.4% or more and 13.7% or less of the incident light is diffused in an angle range of 35 degrees to 55 degrees with respect to a direction perpendicular to the viewer side surface of the diffuser. To do.

  The diffusion film of the present invention is characterized by having the above-described diffuser and a plastic substrate film.

  The polarizing film of this invention has the diffuser mentioned above, a polarizing layer, and a plastic base film, It is characterized by the above-mentioned.

  The liquid crystal display device of the present invention is characterized by having the diffuser described above and a TN liquid crystal panel.

The liquid crystal display device of the present invention is disposed at a position where the surface of the diffuser described above opposite to the viewer is within 1.5 mm from the viewer-side surface of the TN liquid crystal layer of the TN liquid crystal panel. It is characterized by being.
In the diffuser described above, the viewing angle of the color observed when displaying the eight colors for color rendering evaluation on a liquid crystal display device having a TN liquid crystal panel in which the diffuser is arranged on the surface on the viewer side. Is 0 degrees (front direction), 20 degrees, 40 degrees, 60 degrees, and 80 degrees, the color change amount Δu ′ indicated by the coordinate values in the CIE 1976 u′v ′ color system obtained by the following equation (1) In the liquid crystal display device, the maximum value of v ′ is suppressed to half or less of the maximum value of the color change amount Δu′v ′ when the diffuser is not installed. .
Δu′v ′ = {(u ₁ ′ −u ₀ ′) ² + (v ₁ ′ −v ₀ ′) ² } ^0.5 (1)
Here, (u ₀ ′, v ₀ ′) is the coordinate value of the color observed in the front direction, and (u ₁ ′, v ₁ ′) is the CIE 1976 u′v ′ of the color observed by changing the observation angle. It is a coordinate value in the color system.
In the diffusion film described above, the observation angle of the color observed when displaying the eight colors for color rendering evaluation on a liquid crystal display device including a TN type liquid crystal panel in which the diffusion film is arranged on the surface on the viewer side. Is 0 degrees (front direction), 20 degrees, 40 degrees, 60 degrees, and 80 degrees, the color change amount Δu ′ indicated by the coordinate values in the CIE 1976 u′v ′ color system obtained by the following equation (1) The maximum value of v ′ can be suppressed to be equal to or less than half of the maximum value of the color change amount Δu′v ′ when the diffusion film is not installed in the liquid crystal display device. .
Δu′v ′ = {(u ₁ ′ −u ₀ ′) ² + (v ₁ ′ −v ₀ ′) ² } ^0.5 (1)
Here, (u ₀ ′, v ₀ ′) is the coordinate value of the color observed in the front direction, and (u ₁ ′, v ₁ ′) is the CIE 1976 u′v ′ of the color observed by changing the observation angle. It is a coordinate value in the color system.
The polarizing film described above is an observation angle of a color observed when eight colors for color rendering evaluation are displayed on a liquid crystal display device including a TN type liquid crystal panel in which the polarizing film is disposed on the surface on the viewer side. Is 0 degrees (front direction), 20 degrees, 40 degrees, 60 degrees, and 80 degrees, the color change amount Δu ′ indicated by the coordinate values in the CIE 1976 u′v ′ color system obtained by the following equation (1) The maximum value of v ′ may be suppressed to be equal to or less than half of the maximum value of the color change amount Δu′v ′ when the polarizing film is not installed in the liquid crystal display device. .
Δu′v ′ = {(u ₁ ′ −u ₀ ′) ² + (v ₁ ′ −v ₀ ′) ² } ^0.5 (1)
Here, (u ₀ ′, v ₀ ′) is the coordinate value of the color observed in the front direction, and (u ₁ ′, v ₁ ′) is the CIE 1976 u′v ′ of the color observed by changing the observation angle. It is a coordinate value in the color system.

  According to the above configuration, a diffuser, a diffusion film, a polarizing film, and a liquid crystal display that reduce a difference in color and gradation of a display image depending on an observation angle, suppress image blur, and suppress backscattering noise of external light. An apparatus can be provided.

Hereinafter, modes for carrying out the present invention will be described.
(Embodiment 1)
FIG. 1 is a schematic cross-sectional view showing an example of a liquid crystal display device according to an embodiment of the present invention.
As shown in FIG. 1, the liquid crystal display device 13 includes a polarizing film (polarizing plate) 61, a TN type liquid crystal panel 10, a polarizing film 62, and a backlight unit unit 11.

  A polarizing film (polarizing plate) 61 arranged in the front direction f (observer side) is composed of a diffusion film 4, a polarizing layer 7, and a plastic substrate film 52. The diffusion film 4 is composed of a diffuser 1 and a plastic substrate film 51.

  The TN type liquid crystal panel 10 is configured such that a TN type liquid crystal layer 9 is sandwiched between a glass substrate (color filter) 81 and a glass substrate (TFT substrate) 82. The TN type liquid crystal layer 9 includes a plurality of pixels (not shown) that change the orientation of liquid crystal molecules according to the TFT cells of the glass substrate (TFT substrate) 82.

  The polarizing film (polarizing plate) 62 includes a plastic base film 51, a polarizing layer 7, and a plastic base film 52. The backlight unit unit 11 includes a cold cathode fluorescent lamp (CCFL) (not shown) and a light guide plate (not shown) for guiding light from the CCFL in the front direction f (observer side). It consists of and.

  In order to perform optical compensation, a retardation film made of a discotic liquid crystal or the like that is inclined and aligned is provided between the TN liquid crystal panel 10 and the polarizing film 62 and between the TN liquid crystal panel and the polarizing film 61. It may be inserted.

  The plastic substrate films 51 and 52 used in the polarizing films 61 and 62 may be any material having a high light transmittance, and triacetyl cellulose (TAC), polyethylene terephthalate (PET), cycloolefin, or the like is used. it can.

The diffusion film 4 is composed of a diffuser 1 and a plastic base film 61.
The diffuser 1 is formed by dispersing light scattering particles 3 in a forming material 2. A surface 1a opposite to the observer and a surface 1b on the observer side are provided.

  As the material of the forming material 2, various resin materials (binders) such as ionizing radiation curable materials, thermoplastic resins, and thermosetting materials can be used. About the forming material 2, since it is arrange | positioned at the observer side of a liquid crystal display device, what has a hard-coat property is preferable. Therefore, an ionizing radiation curable material that can achieve high surface hardness by curing is particularly preferable.

Examples of the ionizing radiation curable material include an ultraviolet (UV) curable material and an electron beam curable material.
For example, it is preferable to use a resin material having an acrylate functional group such as polyester acrylate or urethane acrylate.
Among these, about polyester acrylate, the oligomer acrylate or methacrylate of a polyester-type polyol, or its mixture can be mentioned. (Hereinafter, acrylate and / or methacrylate will be referred to as (meth) acrylate.)
On the other hand, examples of urethane acrylates include polyol compounds obtained by acrylate-forming oligomers composed of diisocyanate compounds.

  Examples of monomers constituting the acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, methoxyethyl (meth) acrylate, and butoxyethyl (meth). Examples include acrylate and phenyl (meth) acrylate.

Moreover, the forming material 2 may use a polyfunctional monomer together.
Examples of the polyfunctional monomer include trimethylolpropane tri (meth) acrylate, hexanediol (meth) acrylate, tripropylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipenta Examples include erythritol hexa (meth) acrylate, 1,6-hexanediol di (meth) acrylate, and neopentyl glycol di (meth) acrylate.

  Examples of polyester oligomers include adipic acid and glycol (ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, butylene glycol, polybutylene glycol, etc.) and triol (glycerin, trimethylolpropane, etc.), sebacic acid, glycol, and triol. And polyadipate polyol, which is a condensation product with polysebacate polyol, and the like.

Further, a polymerization initiator may be blended with the forming material 2 in order to efficiently proceed the polymerization of the ionizing radiation curable material during curing.
Although there is no restriction | limiting in particular as this polymerization initiator, It is preferable to use the compound which generate | occur | produces a radical when active energy is irradiated. Examples of such a polymerization initiator include 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, and 2-methyl [4- (methylthio) phenyl] -2-morphol. Linopropan-1-one, 2,2-dimethoxy-1,2-diphenylethane-1-one, benzophenone, 1- [4- (2-hydroxyethoxy) phenyl] -2-hydroxy-2-methyl 1-propane- 1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butan-1-one, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, etc. Can be mentioned.
The blending amount of the polymerization initiator is preferably 0.1 to 10 parts by weight, more preferably 1 to 7 parts by weight, still more preferably 100 parts by weight of the forming material 2. 1 to 5 parts by weight.

A solvent can be added to the diffuser solution (coating liquid) in which the forming material 2 and the light scattering particles 3 are mixed, if necessary.
Although the solvent is not particularly limited, for example, ketones such as methyl ethyl ketone, acetone and methyl isobutyl ketone, esters such as methyl acetate, ethyl acetate and butyl acetate, aromatic compounds such as toluene and xylene, diethyl ether, tetrahydrofuran and the like And alcohols such as methanol, ethanol and isopropanol.

  Examples of the light scattering particles 3 include inorganic particles such as aluminum oxide particles, zirconium oxide particles, magnesium oxide particles, silicon oxide particles, and calcium carbonate particles, melamine particles, PMMA particles, polystyrene particles, and styrene / PMMA copolymer particles. Organic particles such as polycarbonate particles, polyurethane particles, nylon particles, polyethylene particles, polypropylene particles, silicone particles, polytetrafluoroethylene particles, polyvinylidene fluoride particles, and polyvinylidene chloride particles can be used.

When the light scattering particles 3 are selected in consideration of the refractive index difference from the forming material 2, when a high refractive index material is required, for example, metal compound particles that are inorganic particles may be used.
For example, aluminum oxide (n = 1.76), zirconium oxide (n = 2.4), zinc sulfide (n = 2.37), zinc oxide (n = 2.01), titanium oxide (n = 2.61) , 2.903) and magnesium oxide (n = 1.72). Among these, aluminum oxide is particularly suitable because it has high chemical stability.
In addition, when the light scattering particles 3 are selected in consideration of the refractive index difference from the forming material 2, when a low refractive index material is required, organic particles such as silicone particles (n = 1.43) are used. It can be used suitably.
The light scattering particles 3 may be composed of two or more kinds of particles of different materials.

For example, when SiO ₂ , ZrO ₂ , Al ₂ O ₃ , ZnO is used as the light scattering particles, by performing a treatment for covering the surface with a transparent resin, a coupling agent, a surfactant, or the like, or The dispersibility of the light-scattering particles 3 with respect to the forming material 2 can be improved by chemically treating the surface with alcohol, amine, organic acid, or the like.

The particle diameter of the light scattering particles 3 is preferably 0.3 to 2.0 μm.
When the particle diameter of the light scattering particles 3 is less than 0.3 μm, the degree of backscattering with respect to incident light becomes large.
On the contrary, when the particle diameter of the light scattering particles 3 exceeds 2.0 μm, the incident light cannot be scattered forward at a wide angle.

  The particle diameter of the light scattering particles 3 is an average value of the diameters of the light scattering particles 3 when the light scattering particles 3 are spherical, and a short diameter when the light scattering particles 3 are spheroids. Use the average value. This particle diameter can be measured by, for example, a particle size distribution analyzer SD-2000 (manufactured by Sysmex Corporation).

The refractive index difference Δn between the forming material 2 and the light scattering particles 3 is preferably 0.05 to 0.25.
When the refractive index difference Δn is less than 0.05, it is not preferable because light cannot be effectively scattered. On the other hand, when the refractive index difference Δn exceeds 0.25, the degree of backscattering with respect to incident light increases. The refractive index difference Δn may be 0.05 to 0.25 in the visible light region. Further, the refractive index of the light scattering particles 3 may be lower or higher than the refractive index of the forming material 2.

Furthermore, when the particle diameter of the light scattering particle 3 is reduced and the refractive index difference Δn between the forming material 2 and the light scattering particle 3 is increased, the backscattered light becomes large and the image is difficult to see in a bright place. Therefore, it is not preferable.
For example, when the particle diameter of the light scattering particle 3 is less than 0.3 μm and the refractive index difference Δn between the forming material 2 and the light scattering particle 3 is more than 0.25, the back scattered light becomes large. .

Usually, when a liquid crystal display or the like is observed in a bright place, reflection or noise is generated on the surface of the liquid crystal display due to reflection by external light. This is called surface reflection. The light intensity of this surface reflection is usually about 4% of the external light.
When the light intensity of the backscattered light is larger than the light intensity of the surface reflection, the influence of the backscattered light becomes difficult to see the display image, and the display image is generally whitish and the image quality of the display image is deteriorated. .
Conversely, when the light intensity of the backscattered light is smaller than the light intensity of the surface reflection, it can be said that the influence of the backscattered light making it difficult to see the display image is small.

  That is, by setting the particle diameter of the light scattering particle 3 to 0.3 μm or more and the refractive index difference Δn between the forming material 2 and the light scattering particle 3 to 0.25 or less, the light intensity of the backscattered light is reduced. The light intensity of the surface reflection can be made smaller, and the influence of making the display image difficult to see can be reduced.

  Further, by setting the particle diameter of the light scattering particle 3 to 2.0 μm or less and making the refractive index difference Δn between the light scattering particle 3 and the forming material 2 less than 0.05, the thickness and light of the diffuser 1 can be reduced. Although depending on the dispersion state of the scattering particles 3, the haze ratio of the diffuser 1 can be 50% or less, and image blur can be suppressed.

The content of the light scattering particles 3 dispersed in the forming material 2 is not particularly defined. The amount of the light scattering particles 3 may be an amount that can be uniformly dispersed in the forming material 2. If the content of the light scattering particles 3 to be dispersed in the forming material 2 is too large and cannot be uniformly dispersed, the light characteristics of the diffuser 1 may vary in the surface, which is not preferable.
Furthermore, the film thickness of the diffuser 1 is not particularly specified.

The haze ratio of the diffuser 1 is preferably 50% or less.
When the haze ratio of the diffuser 1 is 50% or less, the light transmittance is sufficient, and the edge portion of the display image can be clarified to suppress image blur.
Conversely, when the haze ratio of the diffuser 1 exceeds 50%, it is not preferable because the light transmittance is lowered, the edge portion of the display image is unclear, and image blur occurs.
In addition, this haze rate is a value with respect to light in the visible light region, and is measured by, for example, a haze meter (trade name “HM-150” manufactured by Murakami Color Research Co., Ltd.).

FIG. 2 is a schematic view showing a light path in the liquid crystal display device according to the embodiment of the present invention.
First, the light I is emitted from the backlight unit 11.
This light I is polarized by the polarizing layer 7 of the polarizing film 62, then enters the surface 10a opposite to the observer of the TN liquid crystal panel 10, passes through the TN liquid crystal layer 9, and passes through the TN liquid crystal panel. 10 is emitted from the surface 10b on the observer side.
The light emitted from the viewer-side surface 10b of the TN liquid crystal panel 10 enters the polarizing film 61, is polarized by the polarizing layer 7, and then enters the surface 1a opposite to the viewer of the diffuser 1. The

  Further, when the light incident on the diffuser 1 passes through the inside of the diffuser 1, a part of the light is diffused on the inner surface, the transmitted light T that is transmitted as it is, and the inner surface of the diffuser 1 is diffused and emitted. As the emitted light O composed of the diffused light D, the light is emitted in the front direction f from the observer-side surface 1 b of the diffuser 1.

In the diffuser of the present invention, when incident light composed of parallel rays is incident on the surface 1a opposite to the observer of the diffuser 1 from a perpendicular direction, 8% or more of the incident light is observed. It is preferably diffused in an angle range of 35 to 55 degrees (around 45 degrees) with respect to the direction perpendicular to the person-side surface 1b.
By causing the diffuser 1 to emit 8% or more of the light emitted in the front direction f in an angle range of 35 to 55 degrees (around 45 degrees) with respect to the direction perpendicular to the surface 1b on the viewer side, When the display screen is viewed from the horizontal direction, the rate of color change when viewing the display image by changing the observation angle can be reduced.
Conversely, when the light diffused in the angle range of 35 to 55 degrees (around 45 degrees) from the front direction f is less than 8% of the incident light, the color change is effectively suppressed in this way. I can't.

  At this time, since the diffuser 1 is a system in which the light scattering particles 3 are dispersed at random in the forming material 2, it is assumed that the diffused light D is diffused isotropically. Further, it is assumed that the light intensity emitted from the front direction f at the same angle is equal. Further, it is assumed that the light intensity of the diffused light D is a value obtained by adding the light intensities of the light emitted at the same angle from the front direction f.

The surface 9b on the viewer side of the TN type liquid crystal panel 9 and the surface 1a on the opposite side to the viewer of the diffuser 1 are parallel to each other, and the distance between them is arranged within a range of 1.5 mm or less. It is preferable.
This is because image blur can be suppressed by arranging the diffuser 1 and the TN liquid crystal layer 9 close to each other. Note that image blur is a phenomenon in which an edge portion of a pixel becomes unclear.

FIG. 3 is a schematic cross-sectional view for explaining an image blur suppression effect when the diffuser 1 according to the embodiment of the present invention is used. FIG. FIG. 3B is a diagram illustrating the path of light entering the viewer's eyes without changing the traveling direction of the diffuser 1. is there.
The diffuser 1 is disposed on the surface 10b on the observer side of the glass substrate 8, and the eyes of the observer are drawn slightly apart from the surface 1b on the observer side of the diffuser 1.

  In FIG. 3, the TN liquid crystal panel 10 is simply indicated by a glass substrate (color filter) 81 and a pixel 91, and a plastic base film existing between the diffuser 1 and the TN liquid crystal panel 10. Members such as 51 and 52 are omitted.

FIG. 3A shows the light path by the diffused light D. The light indicating the edge portions 91c and 91d in the width direction of the pixel 91 passes along the paths indicated by arrows g and h. Is diffused inside and enters the eyes of the observer. At this time, the observer's eyes observe the width w of the pixel 91 with a width W larger than the actual width.
In the TN type liquid crystal panel 10 used for a general vehicle-mounted liquid crystal display device, the thickness of the glass substrate 81 is about 1 mm, and the width of the pixel 91 is about 200 to 300 μm. Considering this, the width of the pixel 91 is expanded by about 500 μm on both sides, and the image seen by the observer is considerably blurred.

On the other hand, FIG. 3 (b) is due to the light passing through (transmitted light) T, and the light indicating the edge portions 91 c and 91 d in the width direction of the pixel 91 passes along the path indicated by the arrow h. The light is directly incident on the observer's eyes without being internally diffused inside.
At this time, the observer's eyes observe the pixel 91 with the width w. In this way, in the image by the light passing through (transmitted light) T, the light from the edge portions 91c and 91d in the width direction of the pixel 91 enters the eyes as it is without being diffused by the diffuser 1, so The size does not change and the image is not blurred.

  Since the image actually seen by the observer is the outgoing light O that combines the plain light (transmitted light) T and the diffused light D, the ratio of the light intensity of the diffused light D is higher than that of the plain light (transmitted light) T. If it is small, image blurring is suppressed. Further, even when the glass substrate 8 is thin and the width W of the pixel 91 displayed with the diffused light D is not so different from the actual width w of the pixel, the image blur is suppressed.

The haze ratio of the diffuser 1 is preferably 50% or less.
By setting the haze ratio of the diffuser 1 to 50% or less, light of about 50% or more of the incident light can be used as the light passing through (transmitted light) T, and as a result, image blur can be prevented. Because. When the haze ratio of the diffuser 1 is 50% or less, when black characters are displayed on a white background, a contrast necessary for clearly recognizing the characters can be obtained, and at least twice the white background portion and the black character portion. A degree of brightness difference can be obtained.

Thus, by setting the haze ratio of the diffuser 1 to at least 50% or less, the ratio of the light passing through (transmitted light) T can be increased, and as a result, image blur can be prevented.
In addition, since the edge portions 91c and 91d in the width direction of the pixel 91 can be discriminated, a resolution sufficient to recognize fine character information can be obtained.

(Production method of diffuser)
An example of the manufacturing method of the diffuser 1 which is embodiment of this invention is demonstrated.
First, the light scattering particles 3 are mixed with the uncured forming material 2 in a solvent to prepare a diffuser solution (coating solution).
Next, the diffuser solution (coating solution) is applied on the plastic substrate film with a predetermined film thickness. As a coating method, a spin coating method, a roll coating method, a spray method, a bar coating method, a die coating method, a flow coating method, a dipping method, a screen printing method, or the like can be used. As the plastic substrate film, any material having a high light transmittance may be used, and triacetyl cellulose (TAC), polyethylene terephthalate (PET), cycloolefin, and the like can be used.

Next, the diffuser solution (coating solution) is dried and irradiated with radiation such as an electron beam (EB) to harden the forming material 2, whereby light scattering particles are formed on the forming material 2. A diffusion film 4 having a diffuser 1 in which 3 is dispersed can be produced.
In addition to the electron beam irradiation process, an ultraviolet irradiation process, a heating process, and the like can be used as the curing method, and the curing method is set according to the type of the forming material 2.

In order to improve the coating properties, the viscosity of the diffuser solution (coating solution) is preferably 1 to 200 cp (mPa · s), and the ratio of the solid component excluding the solvent in the coating solution is 20 It is preferable to set it as -60 mass%.
By the above, a diffuser can be formed on the plastic substrate film.

  In the diffuser 1 according to the embodiment of the present invention, the light scattering particles 3 are dispersed in the forming material 2, and the refractive index difference Δn between the light scattering particles 3 and the forming material 2 is 0.05 to 0. .25, the light can be effectively scattered and the display image can be easily viewed. It is possible to suppress the color change of the display image that occurs when the observation angle from the front direction f is changed.

  Since the diffuser 1 which is an embodiment of the present invention has a configuration in which the particle diameter of the light scattering particles 3 is 0.3 to 2.0 μm, the color change of the display image that occurs when the observation angle from the front direction f is changed. Can be suppressed.

  Since the diffuser 1 according to the embodiment of the present invention has a haze ratio of 50% or less, the ratio of the light passing through (transmitted light) T can be increased and image blur can be suppressed.

  In the diffuser 1 according to the embodiment of the present invention, when incident light composed of parallel rays is incident from a direction perpendicular to the surface 1a opposite to the observer of the diffuser 1, 8% or more of the incident light is present. Since the diffuser 1 is configured to diffuse in an angle range of 35 to 55 degrees with respect to the direction perpendicular to the viewer-side surface 1b, the color change of the display image that occurs when the observation angle from the front direction f is changed. Can be suppressed.

  The diffuser 1 according to the embodiment of the present invention has a configuration in which the light scattering particles 3 are dispersed in the forming material 2. Therefore, the light can be efficiently transmitted and the luminance can be improved, and the difference in observation angle can be obtained. Color change, color and gradation differences can be suppressed. Furthermore, image blur can be suppressed and external light noise can be suppressed.

  Since the liquid crystal display device 13 according to the embodiment of the present invention has the diffuser 1, the color change due to the difference in the viewing angle of the TN liquid crystal panel 10 can be suppressed, and a good image can be obtained regardless of the viewing angle. Observe. In particular, a clear display can be performed as an in-vehicle liquid crystal display device that is used with a large observation angle.

  Since the diffusing film 4 according to the embodiment of the present invention is composed of the diffuser 1 and the plastic base film 51, the polarizing film 61 is easily attached to the plastic base film 52 including the polarizing layer 7. The manufacturing process of the polarizing film 61 can be simplified, and in the TN type liquid crystal display device using the polarizing film 61, the color change when viewing the display image by changing the observation angle is suppressed, Image blurring can be suppressed, and backscattered light noise can be further suppressed.

  Since the polarizing film 61 according to the embodiment of the present invention is composed of the diffusion film 4, the polarizing layer 7, and the plastic substrate film 52, the polarizing film 61 is easily attached to the observation-side surface 10b of the TN liquid crystal panel 10. It is possible to simplify the manufacturing process of the TN type liquid crystal display device, suppress the color change when viewing the display image by changing the observation angle, suppress the image blur, and further suppress the backscattered light noise. In addition, it is possible to improve the performance of the display image using polarized light.

  Hereinafter, the present invention will be specifically described based on examples. However, the present invention is not limited only to these examples.

  First, the observation angle dependency of the observation color in the TN liquid crystal display device not including the diffuser of the present invention is shown, and then the observation angle dependency of the observation color in the TN liquid crystal display device including the diffuser of the present invention. Indicates. By comparing these, the effect of the diffuser can be clarified.

(Dependence of observation color on observation angle in TN liquid crystal display device)
The TN liquid crystal display device includes a TN liquid crystal panel in which a TN liquid crystal layer is sandwiched between two glass substrates, and a backlight unit. Light emitted from the backlight unit enters the TN type liquid crystal panel, passes through the TN type liquid crystal layer, and is emitted.

FIG. 12 is a graph showing the viewing angle dependence of the color observed when displaying the eight colors for color rendering evaluation on the TN liquid crystal display device, and the coordinate values in the CIE 1976 u′v ′ color system ( u ′, v ′).
The eight colors for evaluating color rendering properties are indicated by coordinate values (u ′, v ′) in the CIE 1976 u′v ′ color system, respectively.

  When the observation angle is 0 degree (front direction), each color is dispersed in the coordinates in the CIE 1976 u′v ′ color system, and each color is accurately displayed in the displayed color. However, the saturation decreased as the observation angle was increased to 20 degrees and 40 degrees. When the observation angle was 80 degrees, a color shift to a yellowish color as a whole was seen unlike the color seen when the observation angle was 0 degrees (front direction).

The color change amount Δu′v ′ when the observation angle is changed is obtained by the following equation (1).
Δu′v ′ = {(u ₁ ′ −u ₀ ′) ² + (v ₁ ′ −v ₀ ′) ² } ^0.5 (1)
Here, (u ₀ ′, v ₀ ′) is the coordinate value of the color observed in the front direction, and (u ₁ ′, v ₁ ′) is the CIE 1976 u′v ′ of the color observed by changing the observation angle. It is a coordinate value in the color system.

FIG. 13 is a graph showing the color change amount Δu′v ′ at different observation angles based on the result obtained in FIG.
The largest color change occurred in the observation angle range of 60 to 80 °, and the maximum value of the color change amount Δu′v ′ exceeded 0.1.

(Dependence of observation color on observation angle in TN liquid crystal display device with diffuser)
(Test Example 1)
Test Example 1 A sample diffuser was prepared by a phase separation method.
First, a diffuser solution in which vinyl acetate and an acrylic monomer were mixed at a ratio of 1: 1 was applied to a TAC film, dried, and then cured to form a diffuser with a thickness of 10 μm on the TAC film. The diffuser thus obtained had a structure in which an acrylic monomer having a spherical structure was dispersed in vinyl acetate and solidified. When the cross section of the obtained diffuser was observed with a scanning electron microscope (SEM), the particle diameter of the acrylic monomer having a spherical structure was 1 to 2 μm. Further, the haze ratio of the diffusion film of the sample of Test Example 1 was 54.2%.

(Test Example 2)
First, a diffuser solution was prepared by dispersing light scattering particles composed of melamine having a refractive index of 1.65 and a particle diameter of 2 μm in an acrylic UV curable resin having a refractive index of 1.53. The particle ratio was 25%.
Next, after applying this diffuser solution on a TAC film, it was exposed to UV light and cured to produce a diffusion film (sample of Test Example 2) having a diffuser with a film thickness of 6 μm. The haze ratio of the diffusion film of Test Example 2 sample was 77.5%.

(Test Examples 3 to 7)
Diffusion films (samples of Test Examples 3 to 7) were produced in the same manner as in Test Example 1 except that the diffuser was produced under the conditions shown in Table 1.

Example 1
First, a diffuser solution was prepared by dispersing light scattering particles composed of melamine having a refractive index of 1.65 and a particle diameter of 0.5 μm in an acrylic UV curable resin having a refractive index of 1.53. The particle ratio was 20%.
Next, after applying this diffuser solution on a TAC film, it was exposed to UV light and cured to produce a diffusion film (Example 1 sample) having a 6 μm thick diffuser. The haze ratio of the diffusion film of Example 1 sample was 42.2%.

FIG. 4 is a graph showing the relationship between the diffusion light intensity of the diffusion film of Example 1 sample and the observation angle.
The light intensity of the diffused light was measured by allowing parallel light to enter the diffused film vertically and changing the observation angle. The diffused light intensity was high when the observation angle was 10 degrees or less, and decreased as the observation angle was increased.
Based on this graph, the ratio of the diffused light in the observation angle range of 35 to 55 degrees with respect to the incident light was calculated. The ratio of the diffused light in the observation angle range of 35 to 55 degrees with respect to the incident light was 11.9%.

  Next, the diffusion film of the sample of Example 1 was disposed on the light emitting surface side of the TN liquid crystal panel to produce a TN liquid crystal display device provided with a diffuser.

FIG. 5 is a graph showing the viewing angle dependence of the color observed when displaying the eight colors for evaluating color rendering on the TN liquid crystal display device. The coordinate values in the CIE 1976 u′v ′ color system ( u ′, v ′).
When the observation angle is 0 degree (front direction), the eight colors for color rendering evaluation are dispersed in the chromaticity coordinates and displayed in the color displayed by the liquid crystal cell. Further, even when the observation angle was increased to 20 degrees and 40 degrees, the saturation did not decrease so much. Even when the observation angle was 80 degrees, the color was not so different from the color seen when the observation angle was 0 degrees (front direction), and almost all colors were displayed in the colors displayed by the liquid crystal cell.

FIG. 6 is a graph showing the color change amount Δu′v ′ at different observation angles based on the result obtained in FIG.
The maximum value of the color change amount Δu′v ′ is 0.034, and no large color change occurred even when the observation angle was changed.

The evaluation of the effect of suppressing the color change due to the difference in observation angle is that the maximum value of the color change amount Δu′v ′ is suppressed to less than half of the maximum value of the color change amount Δu′v ′ when the diffuser 1 is not installed. It was evaluated by whether or not.
For example, when the maximum value of the color change amount Δu′v ′ of the TN liquid crystal panel 10 is 0.1, the maximum value of the color change amount Δu′v ′ when the diffuser 1 is arranged is 0.05 or less ( 50% or less), it was evaluated that the diffuser 1 was installed to suppress the color change due to the difference in observation angle.

  When the diffusion film of Example 1 sample was used, the maximum value of the color change amount Δu′v ′ was about 34% of the maximum value of the color change amount Δu′v ′ when no diffusion film was arranged. . Therefore, it was evaluated that the diffusion film of Example 1 sample had an effect of suppressing color change due to a difference in observation angle.

(Example 2)
First, a diffuser solution was prepared by dispersing an alumina filler having a refractive index of 1.76 and a particle diameter of about 0.4 μm in an acrylic UV curable resin having a refractive index of 1.53. The particle ratio was 8%.
Next, after applying this diffuser solution on a TAC film, it was exposed to UV light and cured to prepare a diffusion film (Example 2 sample) having a diffuser with a film thickness of 11 μm. The haze ratio of the diffusion film of Example 2 sample was 46.9%.

  FIG. 7 is a graph showing the relationship between the diffusion light intensity and the observation angle of the diffusion film of Example 2 sample. The ratio of the diffused light in the observation angle range of 35 to 55 degrees with respect to the incident light was 10.4%.

  Next, the diffusion film of Example 2 sample was disposed on the light emitting surface side of the TN type liquid crystal panel to produce a TN type liquid crystal display device provided with a diffuser.

FIG. 8 is a graph showing the viewing angle dependence of the color observed when displaying the eight colors for evaluating the color rendering properties on the TN liquid crystal display device, and the coordinate values in the CIE 1976 u′v ′ color system ( u ′, v ′).
When the observation angle is 0 degree (front direction), the eight colors for color rendering evaluation are dispersed in the chromaticity coordinates and displayed in the color displayed by the liquid crystal cell. Further, even when the observation angle was increased to 20 degrees and 40 degrees, the saturation did not decrease so much. Even when the observation angle was 80 degrees, the color was not so different from the color seen when the observation angle was 0 degrees (front direction), and almost all colors were displayed in the colors displayed by the liquid crystal cell.

FIG. 9 is a graph showing the color change amount Δu′v ′ at different observation angles based on the result obtained in FIG.
The maximum value of the color change amount Δu′v ′ is 0.042, and a large color change does not occur even when the observation angle is changed.

  When the diffusion film of Example 2 sample was used, the maximum value of the color change amount Δu′v ′ was about 42% of the maximum value of the color change amount Δu′v ′ when no diffusion film was arranged. . Therefore, it was evaluated that the diffusion film of Example 1 sample had an effect of suppressing color change due to a difference in observation angle.

(Example 3)
First, a diffuser solution was prepared in which light scattering particles made of melamine having a refractive index of 1.65 and a particle diameter of about 0.5 μm were dispersed in an acrylic UV curable resin having a refractive index of 1.53. The particle ratio was 25%.
Next, after applying this diffuser solution on a TAC film, it was exposed to UV light and cured to prepare a diffusion film (Example 3 sample) having a diffuser with a film thickness of 11 μm. The haze ratio of the diffusion film of Example 3 sample was 49.1%.

  Table 1 is a table | surface which shows the preparation conditions of the diffusers of Test Examples 1-7 and Examples 1-3. Table 2 is a table showing the maximum value of the color change amount Δu′v ′ of Test Examples 1 to 7 and Examples 1 to 3 and the ratio of light in the angle range where the observation angle is 35 degrees to 55 degrees. . Table 3 is the table | surface which showed the haze rate of Test Examples 1-7 sample and Examples 1-3 sample. Table 4 is a table showing the difference in refractive index between the forming material and the scattering particles of Test Examples 1 to 7 and Examples 1 to 3 and the particle diameters of the light scattering particles.

As can be seen from Table 2, in the test examples 4 and 5, the maximum value of the color change amount Δu′v ′ is large, and even when these diffusers are installed, the color change that occurs when the observation angle is changed is suppressed. I could hardly do anything. These diffusers had a low light ratio in the angle range of 35 to 55 degrees.
On the contrary, when the ratio of light in the angle range of 35 ° to 55 ° is about 8% or more, the maximum value of the color change amount Δu′v ′ is 0.05 or less, and the color change amount is reduced. It was found that the rate of color change due to the difference in observation angle can be suppressed.

FIG. 10 shows four diffusers (A: Test Example 1, B: Test Example 2, C: Test Example 3, D: Example 1) having the same maximum value of the color change amount Δu′v ′. It is a graph which shows the observation angle dependence of diffused light intensity.
As the incident light, incident light composed of parallel rays from the front direction was used. As shown in FIG. 10, the diffused light intensities of the four diffusers differed greatly depending on the observation angle. However, when the observation angle is around 45 degrees, that is, in the angle range where the observation angle is 35 degrees to 55 degrees, the four diffusers showed substantially the same diffused light intensity.

FIG. 11 shows the relationship between the ratio of diffused light and the observation angle with respect to the four diffusers (A: Test Example 1, B: Test Example 2, C: Test Example 3, D: Example 1) used in FIG. It is a graph to show. The ratio of diffused light is the ratio of diffused light in incident light.
In the samples except Example 1, the ratio of diffused light was high in the observation angle range of 20 degrees or less, and the tendency for the ratio of diffused light to decrease as the observation angle was increased was obtained.
However, the ratio of diffused light in the observation angle range of around 45 degrees, that is, in the angle range where the observation angle ranged from 35 degrees to 55 degrees was about 10% for all samples.

As shown in Tables 1 to 4, four diffusers (A: Test Example 1, B: Test Example 2, C: Test Example 3, D: Example 1) have a particle diameter, a refractive index of scattering particles, Although the diffuser thickness and other values were different, there was almost the same color change suppression effect.
From the above results, it was found that the ratio of diffused light in the direction where the observation angle is around 45 degrees strongly affects the suppression of color change.
Next, image blur and backscattering noise were evaluated.

(Image blur suppression effect in a TN liquid crystal display device including a diffuser)
Regarding the evaluation of the effect of suppressing the image blur, for example, black characters were displayed on a white background or white characters were displayed on a black background, and it was examined whether or not characters could be sufficiently discriminated from the front and oblique directions. The samples of Examples 1 to 3 and the sample of Test Example 4 can sufficiently distinguish characters, and as shown in Table 3, those having a haze ratio of 50% or less may have an effect of suppressing image blur. I understood.

(Suppression effect of backscattered light noise in TN liquid crystal display device provided with diffuser)
The effect of suppressing the backscattering noise was evaluated by actually displaying an image on a TN liquid crystal display device provided with a diffuser and observing it in a bright room. All samples were at a level where little backscattered light noise was noticeable.

  Finally, an image was actually displayed on a TN liquid crystal display device provided with a diffuser, and observed. A satisfactory image was observed in such a way that the ratio of the color change with respect to the observation angle and the change in gradation were hardly noticed.

It is the schematic which shows the TN type | mold liquid crystal display device provided with the diffuser of this invention. It is the schematic which shows the path | route of the light of TN type | mold liquid crystal display device provided with the diffuser of this invention. It is the schematic explaining the image blur of a TN type | mold liquid crystal display device. It is a graph which shows the relationship between the diffused light intensity at the time of using the diffuser of this invention, and an observation angle. It is a graph which shows the chromaticity coordinate value of eight colors for color rendering evaluation at the time of using the diffuser of this invention. It is a graph which shows the relationship between the color change amount of eight colors for color rendering properties evaluation at the time of using the diffuser of this invention, and an observation angle. It is a graph which shows the relationship between the diffused light intensity at the time of using the diffuser of this invention, and an observation angle. It is a graph which shows the chromaticity coordinate value of eight colors for color rendering evaluation at the time of using the diffuser of this invention. It is a graph which shows the relationship between the color change amount of eight colors for color rendering properties evaluation at the time of using the diffuser of this invention, and an observation angle. It is a graph which shows the relationship between the diffused light intensity at the time of using the diffuser of this invention, and an observation angle. It is a graph which shows the relationship between the ratio of the diffused light at the time of using the diffuser of this invention, and an observation angle. It is a graph which shows the chromaticity coordinate value of eight colors for color rendering properties evaluation of a TN type | mold liquid crystal display device. It is a graph which shows the relationship between the color change amount of 8 colors for color rendering properties evaluation of a TN type | mold liquid crystal display device, and an observation angle.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Diffuser, 1a ... Surface on the opposite side to an observer, 1b ... Observer side surface, 2 ... Forming material, 3 ... Light scattering particle, 4 ... Diffusing film, 7 ... Polarizing layer, 9 ... TN type liquid crystal Layer, 9a ... Opposite side, 9b ... Observer side, 10 ... TN type liquid crystal panel, 10a ... Opposite side, 10b ... Observer side, 11 ... Backlight unit , 13 ... TN type liquid crystal display device, 51, 52 ... Plastic base film, 61, 62 ... Polarizing film (polarizing plate), 81 ... Glass substrate (color filter), 82 ... Glass substrate (TFT), 91 ... Pixel.

Claims (8)

Used in a liquid crystal display device having a TN type liquid crystal panel,
A diffuser disposed on a viewer-side surface of the TN liquid crystal panel;
The diffuser is formed by dispersing light scattering particles in a forming material,
The refractive index difference Δn between the light scattering particles and the forming material is 0.12 or more and 0.23 or less ,
The light scattering particles have a particle size of 0.4 μm or more and 0.5 μm or less ,
The haze ratio of the diffuser is 42.2% or more and 49.1% or less ,
When incident light composed of parallel rays is incident from a direction perpendicular to the surface opposite to the diffuser observer, 10.4% or more and 13.7% or less of the incident light is observed by the diffuser observer. A diffuser characterized by being diffused in an angle range of 35 to 55 degrees with respect to a direction perpendicular to the side surface.   A diffusion film comprising the diffuser according to claim 1 and a plastic substrate film.   A polarizing film comprising the diffuser according to claim 1, a polarizing layer, and a plastic substrate film.   A liquid crystal display device comprising the diffuser according to claim 1 and a TN liquid crystal panel.   The surface of the diffuser according to claim 1 opposite to the viewer is disposed at a position within 1.5 mm from the viewer-side surface of the TN liquid crystal layer of the TN liquid crystal panel. The liquid crystal display device according to claim 4. The observation angle of the color observed when displaying the eight colors for evaluating the color rendering on a liquid crystal display device including a TN type liquid crystal panel in which the diffuser is arranged on the surface on the viewer side is 0 degree (front direction). , 20 degrees, 40 degrees, 60 degrees, and 80 degrees, the maximum value of the color change amount Δu′v ′ indicated by the coordinate values in the CIE 1976 u′v ′ color system obtained by the following equation (1) is:
2. The diffuser according to claim 1, wherein the diffuser is suppressed to half or less of a maximum value of the color change amount Δu′v ′ when the diffuser is not installed in the liquid crystal display device.
Δu′v ′ = {(u ₁ ′ −u ₀ ′) ² + (v ₁ ′ −v ₀ ′) ² } ^0.5 (1)
Here, (u ₀ ′, v ₀ ′) is the coordinate value of the color observed in the front direction, and (u ₁ ′, v ₁ ′) is the CIE 1976 u′v ′ of the color observed by changing the observation angle. It is a coordinate value in the color system. The observation angle of the color observed when displaying eight colors for color rendering evaluation on a liquid crystal display device including a TN type liquid crystal panel in which the diffusion film is arranged on the surface on the viewer side is 0 degree (front direction). , 20 degrees, 40 degrees, 60 degrees, and 80 degrees, the maximum value of the color change amount Δu′v ′ indicated by the coordinate values in the CIE 1976 u′v ′ color system obtained by the following equation (1) is:
3. The diffusion film according to claim 2, wherein the diffusion film is suppressed to half or less of a maximum value of the color change amount Δu′v ′ when the diffusion film is not installed in the liquid crystal display device.
Δu′v ′ = {(u ₁ ′ −u ₀ ′) ² + (v ₁ ′ −v ₀ ′) ² } ^0.5 (1)
Here, (u ₀ ′, v ₀ ′) is the coordinate value of the color observed in the front direction, and (u ₁ ′, v ₁ ′) is the CIE 1976 u′v ′ of the color observed by changing the observation angle. It is a coordinate value in the color system. The observation angle of the color observed when displaying the eight colors for color rendering evaluation on a liquid crystal display device having a TN type liquid crystal panel in which the polarizing film is arranged on the surface on the viewer side is 0 degree (front direction). , 20 degrees, 40 degrees, 60 degrees, and 80 degrees, the maximum value of the color change amount Δu′v ′ indicated by the coordinate values in the CIE 1976 u′v ′ color system obtained by the following equation (1) is:
The polarizing film according to claim 3, wherein the polarizing film is suppressed to a half or less of a maximum value of the color change amount Δu′v ′ when the polarizing film is not installed in the liquid crystal display device.
Δu′v ′ = {(u ₁ ′ −u ₀ ′) ² + (v ₁ ′ −v ₀ ′) ² } ^0.5 (1)
Here, (u ₀ ′, v ₀ ′) is the coordinate value of the color observed in the front direction, and (u ₁ ′, v ₁ ′) is the CIE 1976 u′v ′ of the color observed by changing the observation angle. It is a coordinate value in the color system.

Images