WO2012036271A1 - 光拡散素子、光拡散素子付偏光板、およびこれらを用いた液晶表示装置 - Google Patents
光拡散素子、光拡散素子付偏光板、およびこれらを用いた液晶表示装置 Download PDFInfo
- Publication number
- WO2012036271A1 WO2012036271A1 PCT/JP2011/071230 JP2011071230W WO2012036271A1 WO 2012036271 A1 WO2012036271 A1 WO 2012036271A1 JP 2011071230 W JP2011071230 W JP 2011071230W WO 2012036271 A1 WO2012036271 A1 WO 2012036271A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- light diffusing
- diffusing element
- light
- refractive index
- fine particles
- Prior art date
Links
Images
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/02—Diffusing elements; Afocal elements
- G02B5/0205—Diffusing elements; Afocal elements characterised by the diffusing properties
- G02B5/0236—Diffusing elements; Afocal elements characterised by the diffusing properties the diffusion taking place within the volume of the element
- G02B5/0242—Diffusing elements; Afocal elements characterised by the diffusing properties the diffusion taking place within the volume of the element by means of dispersed particles
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/02—Diffusing elements; Afocal elements
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/02—Diffusing elements; Afocal elements
- G02B5/0273—Diffusing elements; Afocal elements characterized by the use
- G02B5/0278—Diffusing elements; Afocal elements characterized by the use used in transmission
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/30—Polarising elements
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
- G02F1/133504—Diffusing, scattering, diffracting elements
Definitions
- the present invention relates to a light diffusing element, a polarizing plate with a light diffusing element, and a liquid crystal display device using these.
- Light diffusing elements are widely used in lighting covers, projection television screens, surface light emitting devices (for example, liquid crystal display devices), and the like.
- light diffusing elements have been increasingly used for improving display quality of liquid crystal display devices and the like, and improving viewing angle characteristics.
- As the light diffusing element an element in which fine particles are dispersed in a matrix such as a resin sheet has been proposed (for example, see Patent Document 1).
- a light diffusing element most of the incident light is scattered forward (exit surface side), but a part is scattered backward (incident surface side).
- the diffusivity for example, haze value
- backscattering increases.
- a technique has been proposed in which a light diffusing element is disposed on the outermost surface of a liquid crystal display device in order to improve the display quality of the liquid crystal display device.
- a light diffusing element has sufficient light diffusibility.
- the haze value is less than 90%
- the effect of improving the display quality is insufficient.
- a light diffusing element having high light diffusibility for example, having a haze value of 90% or more
- the screen is displayed when external light is incident on the liquid crystal display device. There is a problem that it becomes whitish and it is difficult to display a high-contrast video or image in a bright place.
- the fine particles in the light diffusing element scatter incident light not only forward but also backward.
- the larger the haze value the larger the backscattering. Therefore, it is extremely difficult to achieve both the increase in light diffusibility and the suppression of backscattering. Furthermore, in lighting applications, as the haze value increases, backscattering increases and the total light transmittance decreases, so that the light utilization efficiency decreases.
- the core-shell fine particles having different refractive indexes of the core and the shell, or continuous from the center of the fine particles toward the outside
- refractive index gradient fine particles such as so-called GRIN (gradient index) fine particles whose refractive index changes in a resin
- GRIN gradient index
- the present invention has been made to solve the above-described conventional problems, and an object of the present invention is to provide a thin-film light diffusing element capable of realizing low backscattering and high haze.
- a light diffusing element includes a first region having a first refractive index and a second region having a second refractive index, the first region and the second region. These regions are fine irregularities and form a spherical shell boundary.
- a light diffusing element includes a matrix and light diffusing fine particles dispersed in the matrix, and has a refractive index at or near the interface between the matrix and the light diffusing fine particles. Two different regions form a fine rugged and spherical shell-like boundary.
- the matrix includes a resin component and an ultrafine particle component, and the fine uneven and spherical shell boundary is not dispersed with a region in the matrix where the ultrafine particle component is dispersed. Region.
- the fine concavo-convex and spherical shell-like boundary is formed by concavo-convexities on the surface of the light diffusing fine particles.
- the average primary particle diameter of the ultrafine particle component is 1 nm to 100 nm.
- the light diffusing element has a haze of 90% to 99.9%.
- the light diffusing element has a thickness of 4 ⁇ m to 50 ⁇ m.
- the light diffusing element has a light diffusing half-value angle of 10 ° to 150 °.
- a polarizing plate with a light diffusing element is provided. This polarizing plate with a light diffusing element has the above light diffusing element and a polarizer.
- a liquid crystal display device is provided. The liquid crystal display device includes a liquid crystal cell, a parallel light source device that emits collimated light toward the liquid crystal cell, and the light diffusing element that transmits and diffuses the collimated light that has passed through the liquid crystal cell. .
- the first region having the first refractive index and the second region having the second refractive index form a fine concavo-convex and spherical shell-like boundary, thereby reducing the rearward direction.
- a thin-film light diffusing element capable of realizing scattering and high haze can be obtained.
- FIG. 2A viewed from one direction. It is a three-dimensional reconstruction image from the TEM image of FIG. 2A viewed from another direction.
- FIG. 3B is a diagram obtained by binarizing the three-dimensional reconstructed image of FIG. 2B and illustrating a method for calculating the dispersion concentration (existence ratio) of the ultrafine particle component in the vicinity of the interface between the matrix and the light diffusing fine particles.
- 3B is a three-dimensional reconstruction image for explaining a method for obtaining the average pitch and the average height of the unevenness of the fine unevenness boundary from the three-dimensional reconstruction images of FIGS. 2B and 2C.
- FIG. 1 is a schematic cross-sectional view of a liquid crystal display device according to a preferred embodiment of the present invention. It is the schematic of the parallel light source device used by this invention. It is the schematic of another form of the parallel light source device used by this invention. It is a schematic diagram for demonstrating the method of calculating a half value angle in this invention.
- FIG. 12 is a TEM image of the vicinity of a light diffusing fine particle of the light diffusing element of Example 10.
- 6 is a TEM image of the vicinity of a light diffusing fine particle of the light diffusing element of Comparative Example 2.
- the light diffusing element of the present invention has a first region having a first refractive index and a second region having a second refractive index.
- the light diffusing element of the present invention exhibits a light diffusing function due to a difference in refractive index between the first region and the second region.
- the first region and the second region are fine irregularities and form a spherical shell boundary. Therefore, in the light diffusing element of the present invention, the first region surrounded by the fine concavo-convex boundary and the spherical shell shape is dispersed in the second region.
- the size of the fine irregularities at the boundary is preferably not more than the wavelength of light.
- the first region, the second region, and the boundary can be formed by any appropriate means.
- the following means can be cited: (1)
- the outline of the refractive index gradient portion of the refractive index gradient fine particles (for example, so-called GRIN fine particles) whose refractive index continuously changes from the center to the outside of the fine particles. It is formed so as to have an uneven shape, and the fine particles are dispersed in the resin. In this case, the uneven refractive index gradient portion corresponds to the boundary.
- the outer shell can be formed into a concavo-convex shape by treating the surface of the fine particles with a solvent, for example; (2) using a resin component and an ultrafine particle component for the matrix, and a substantial gradient of the dispersion concentration of the ultrafine particle component
- a resin component and an ultrafine particle component for the matrix, and a substantial gradient of the dispersion concentration of the ultrafine particle component
- the light diffusing element of the present invention has a matrix and light diffusing fine particles dispersed in the matrix.
- the light diffusing element of this embodiment exhibits a light diffusing function due to the difference in refractive index between the matrix and the light diffusing fine particles.
- two regions having different refractive indexes are formed in a fine concavo-convex shape and a spherical shell shape at or near the interface between the matrix and the light diffusing fine particles.
- the size of the fine irregularities at the boundary is preferably not more than the wavelength of light.
- a modulation region having a substantial refractive index corresponding to the height of the unevenness is formed between the matrix and the light diffusibility. It is formed at or near the interface with the fine particles.
- the interface between the matrix and the light diffusing fine particles or the vicinity thereof includes the surface of the light diffusing fine particles, the outside near the surface, and the inside near the surface. That is, at the interface between the light diffusing fine particles having a fine uneven surface and the light diffusing fine particles and a matrix having a different refractive index, a fine uneven boundary is formed due to the surface properties of the light diffusing fine particles.
- the surface of the light diffusing fine particles may have fine irregularities and may form fine irregularities due to the surface properties; There may be an interface between two regions having different refractive indexes inside the diffusive fine particles, and the interface may form a fine uneven boundary; two different refractive indexes in the matrix near the surface of the light diffusing fine particles. There may be an interface of regions, and the interface may form a fine uneven boundary.
- the matrix is substantially Specifically, it has the refractive index modulation region at or near the interface with the light diffusing fine particles, and the refractive index constant region outside thereof. In the refractive index modulation region, the refractive index changes substantially continuously.
- the refractive index changes substantially continuously means that the refractive index changes substantially continuously from at least the surface of the light diffusing fine particles to the constant refractive index region in the refractive index modulation region. Means that.
- FIG. 1A is a schematic cross-sectional view of the light diffusing element according to the present embodiment
- FIG. 1B is a schematic diagram for explaining a refractive index modulation region by a fine uneven boundary formed near the surface of the light diffusing fine particles
- FIG. 1C is a schematic diagram for explaining the details of the fine uneven boundary of FIG. 1B
- FIG. 1D illustrates the state of the matrix that can form the fine uneven boundary of FIG. 1B. It is a schematic diagram for doing.
- the matrix preferably includes a resin component and an ultrafine particle component.
- a light diffusing element 100 in FIG. 1A includes a matrix 10 including a resin component 11 and an ultrafine particle component 12, and light diffusing fine particles 20 dispersed in the matrix 10.
- a refractive index modulation region 30 is formed outside the vicinity of the interface between the matrix and the light diffusing fine particles.
- the refractive index modulation region 30 exhibits a refractive index modulation function due to the fine uneven boundary 25 as described above.
- the refractive index modulation region 30 changes substantially continuously.
- the fine uneven boundary 25 is formed at or near the interface between the matrix and the light diffusing fine particles, it has a substantially spherical shell shape.
- the region where the light diffusing fine particles and the ultrafine particle component in the matrix are not dispersed corresponds to the first region, and the region where the ultrafine particle component is dispersed in the matrix is the first region. This corresponds to the area of 2.
- the fine concavo-convex boundary preferably has uneven pitch, concavo-convex depth or convex height, and concave and convex shapes, respectively. is there.
- the average height of the unevenness at the fine unevenness boundary is preferably 10 nm to 500 nm, and more preferably 10 nm to 60 nm.
- the average pitch of the fine concavo-convex boundary is preferably 100 nm or less, more preferably 50 nm or less, and further preferably 30 nm or less.
- the lower limit of the average pitch is preferably 5 nm, and more preferably 10 nm. With such an average pitch and average height, the refractive index can be changed substantially continuously in the refractive index modulation region, and the gradient of the refractive index change can be made steep. As a result, a thin-film light diffusing element having a high haze value, strong diffusibility, and suppressed backscattering can be obtained.
- the average pitch means a statistical average of the horizontal distances between the vertices and vertices of adjacent convex portions in a predetermined range
- the average height means the height of the convex portions in the predetermined range (vertical to vertex). The vertical average). For example, as shown in FIG.
- the fine concavo-convex boundary as described above has fine conical and / or needle-like projections from the light diffusing fine particles toward the matrix (note that the fine concavo-convex The boundary is the same when viewed from the matrix side, and has fine conical and / or needle-like projections toward the light diffusing fine particles).
- a light diffusing element having a low reflectance can be obtained.
- the matrix 10 preferably includes the resin component 11 and the ultrafine particle component 12.
- the region where the ultrafine particle component 12 in the matrix 10 is dispersed and the region where the ultrafine particle component 12 is not dispersed form a fine uneven boundary, and the matrix and light diffusibility are formed.
- a substantial gradient of the dispersion concentration of the ultrafine particle component is formed.
- the refractive index modulation function can be manifested due to the shape of the entire boundary of the fine unevenness, but when viewed more microscopically, even within each protrusion of the protrusion group at the boundary, ultrafine particles
- the dispersed concentration of the components can form a substantial gradient.
- FIG. 2A is a two-dimensional TEM image showing the dispersion state of the ultrafine particle component in the vicinity of the light diffusing fine particles
- FIGS. 2B and 2C are three-dimensional reconstructed images from the TEM image of FIG. 2A viewed from different directions.
- FIG. 2D is a binarized version of the three-dimensional reconstruction image of FIG. 2B.
- FIG. 3 is a graph showing the relationship between the distance from the surface of the light diffusing fine particles calculated from the TEM images of FIGS. 2A to 2C and the dispersion concentration (existence ratio) of the ultrafine particle component. The graph of FIG.
- FIG. 3 shows that the vicinity of the interface between the matrix of FIG. 2D and the light diffusing fine particles is divided into five analysis areas, image processing is performed for each of the five analysis areas, and the surface of the light diffusing fine particles in each analysis area. Calculated from the relationship between the distance from the distance and the dispersion concentration (existence ratio) of the ultrafine particle component is averaged and graphed.
- the ratio of the region in which the ultrafine particle component 12 is not dispersed (or the region having a low dispersion concentration) as the distance from the constant refractive index region of the matrix 10 increases. Will increase.
- FIG. 1 the ratio of the region in which the ultrafine particle component 12 is not dispersed
- the dispersion concentration of the ultrafine particle component is such that the gradient of the concentration change is small on the side close to the light diffusing fine particle 20 and large on the side close to the constant refractive index region. It changes while forming a substantial gradient from the active particle side to the refractive index constant region side.
- the dispersion concentration of the ultrafine particle component 12 increases as the gradient of the concentration change moves away from the light diffusing fine particles.
- the fine uneven boundary has a conical and / or needle-like fine protrusion group from the light diffusing fine particles toward the matrix. A in FIG.
- 2D represents a position corresponding to the surface of the light diffusing fine particles
- B represents a position corresponding to the interface between the refractive index modulation region and the constant refractive index region.
- the average pitch and the average height of the projections and depressions at the boundary of the fine projections and depressions as described above are calculated from the three-dimensional reconstructed images shown in FIGS. 2B and 2C, as shown in FIG. 2E.
- the interface between the matrix and the matrix (real interface) is extracted, and fitting with an approximate curved surface is performed on the real interface, and the distance between the convex portions protruding from the approximate curved surface by 30 nm or more and the average height of the convex portions at the real interface Can be calculated.
- the equiconcentration interface of the ultrafine particle component 12 forms a fine irregular boundary at or near the interface between the matrix and the light diffusing fine particles, and the dispersion concentration of the ultrafine particle component is reduced.
- the refractive index modulation region 30 can be formed by forming a substantial gradient, the light diffusing element can be manufactured by a simple procedure and at a low cost.
- the refractive index can be smoothly changed at the boundary between the refractive index modulation region 30 and the constant refractive index region by forming the refractive index modulation region using a substantial gradient of the dispersion concentration of the ultrafine particle component. it can.
- the difference in refractive index between the light diffusing fine particles and the matrix is increased, and The refractive index gradient in the refractive index modulation region can be made steep.
- a thin-film light diffusing element having a high haze value, strong diffusibility, and suppressed backscattering can be obtained.
- the fine uneven boundary can be formed by appropriately selecting the resin component and ultrafine particle component of the matrix, the constituent material of the light diffusing fine particles, and the chemical and thermodynamic characteristics.
- the resin component and the light diffusing fine particles are composed of the same type of material (for example, organic compounds), and the ultra fine particle component is composed of a different type of material (for example, an inorganic compound) from the resin component and the light diffusing fine particles.
- a fine uneven boundary (as a result, a refractive index modulation region) can be formed satisfactorily.
- the resin component and the light diffusing fine particles are composed of highly compatible materials among the similar materials.
- the shape of the fine irregular boundary (as a result, the thickness of the refractive index modulation region and the refractive index gradient) can be achieved by adjusting the chemical and thermodynamic properties of the resin component and ultrafine particle component of the matrix and the light diffusing fine particles. Can be controlled.
- “same system” means that chemical structures and properties are equivalent or similar, and “different system” means something other than the same system. Whether or not they are related may differ depending on how the reference is selected. For example, when organic or inorganic is used as a reference, the organic compounds are the same type of compounds, and the organic compound and the inorganic compound are different types of compounds.
- the polymer repeat unit when used as a reference, for example, an acrylic polymer and an epoxy polymer are different compounds despite being organic compounds, and when a periodic table is used as a reference, alkali metals and transition metals are used. Is an element of a different system despite being inorganic elements.
- the substantial gradient of the dispersion concentration of the ultrafine particle component as described above can be realized by the following (1) to (2) or an appropriate combination thereof:
- (1) Ultra in the matrix Adjust the dispersion concentration of the fine particle component. For example, by increasing the dispersion concentration of the ultrafine particle component, the electrical repulsion between the ultrafine particle components increases, and as a result, the ultrafine particle component exists near the light diffusing fine particles, and in the refractive index modulation region. A steep refractive index gradient can be formed (the thickness of the refractive index modulation region is reduced).
- the degree of freedom of constituent polymer molecules on the surface of the fine particle is increased, so that the ultrafine particle component is difficult to approach.
- a gradual refractive index gradient can be formed in the refractive index modulation region (the thickness of the refractive index modulation region is increased).
- a substantial gradient of the dispersion concentration of the ultrafine particle component as described above can be realized by appropriately combining the above (1) and (2).
- the dispersion concentration of the ultrafine particle components is set to 30 to 70 parts by weight with respect to 100 parts by weight of the matrix, and the resin component described later
- the dispersion concentration of the ultrafine particle component 12 in the matrix 10 is small on the side close to the light diffusing fine particles 20, and the refractive index is constant.
- a dispersion concentration gradient which is large on the side close to the region and changes while forming a substantial gradient from the light diffusion fine particle side to the constant refractive index region side can be realized.
- the “swelling degree” refers to the ratio of the average particle size of the swollen particles to the average particle size of the particles before swelling.
- the average thickness L of the refractive index modulation region 30 is preferably 10 nm to 500 nm, more preferably 12 nm to 400 nm, and further preferably 15 nm to 300 nm. According to the present invention, the refractive index difference between the light diffusing fine particles and the matrix is increased while the refractive index modulation region is much thinner than the conventional GRIN fine particles (the refractive index gradient is steep), and The refractive index can be changed substantially continuously in the refractive index modulation region.
- the average thickness L is the thickness of the region where the refractive index changes from the vicinity of the surface of the light diffusing fine particles to the constant refractive index region.
- the refractive index can preferably change substantially continuously. More preferably, in addition to this, the outermost refractive index of the refractive index modulation region and the refractive index of the constant refractive index region are substantially the same.
- the refractive index continuously changes from the refractive index modulation region to the constant refractive index region, and preferably the refractive index continuously from the light diffusing fine particles to the constant refractive index region. It changes (FIG. 4). More preferably, the refractive index change is smooth as shown in FIG.
- the shape changes so that a tangent line can be drawn on the refractive index change curve.
- the gradient of refractive index change increases as the distance from the light diffusing fine particles increases.
- a substantially continuous refractive index change can be realized by appropriately selecting the light diffusing fine particles, the resin component of the matrix, and the ultrafine particle component.
- the refractive index is steep and substantially continuous as described above.
- the refractive index difference between the matrix 10 (substantially constant refractive index region) and the light diffusing fine particles 20 is increased, reflection at the interface between the matrix 10 and the light diffusing fine particles 20 can be suppressed. And backscattering can be suppressed.
- the weight concentration of the ultrafine particle component 12 having a refractive index greatly different from that of the light diffusing fine particles 20 is relatively high, so that the matrix 10 (substantially the refractive index constant region) and light The difference in refractive index with the diffusible fine particles 20 can be increased. As a result, high haze (strong diffusivity) can be achieved even with a thin film.
- the backscattering can be remarkably suppressed while realizing a high haze by increasing the refractive index difference.
- Such a feature is particularly suitable for applications that require strong diffusibility (haze of 90% or more), such as a light diffusing element used in a collimated backlight front diffusion system.
- a strong diffusivity high haze value
- the refractive index gap at the interface is eliminated. I can't.
- black display is often not sufficiently black (so-called black floats) in the presence of external light.
- the present invention by forming the above-mentioned fine uneven boundary, and consequently forming a refractive index modulation region in which the refractive index continuously changes, the above-mentioned problems of the prior art are solved, and the haze value is high, A thin-film light diffusing element having strong diffusibility and suppressing backscattering can be obtained.
- the average refractive index n M of the matrix is preferably larger than the refractive index n P of the light diffusing fine particles (n M > n P ).
- n M > n P the refractive index gradient of the refractive index modulation region is larger than when n M ⁇ n P. Even if the is steep, backscattering can be suppressed more favorably.
- the upper limit of ⁇ n is preferably 0.2.
- the light diffusion characteristics of the light diffusing element of the present invention are typically represented by haze and light diffusion half-value angle.
- the haze indicates the intensity of light diffusion, that is, the degree of diffusion of incident light.
- the light diffusion half-value angle indicates the quality of diffused light, that is, the angle range of light to be diffused.
- the effect of the light diffusing element of the present invention is sufficiently exhibited when the haze is high.
- the haze of the light diffusing element is preferably 90% to 99.9%, more preferably 92% to 99.9%, still more preferably 95% to 99.9%, and particularly preferably 97%. ⁇ 99.9%.
- the collimated backlight front diffusing system means a collimated backlight light (condensed backlight in a certain direction and having a narrow luminance half-value width (for example, 3 ° to 35 ° or ⁇ 1.5 ° to ⁇ (17.5 °) backlight light), and a system in which a front light diffusing element is provided on the viewing side of the upper polarizing plate.
- the light diffusing characteristic of the light diffusing element is preferably 10 ° to 150 ° (5 ° to 75 ° on one side), more preferably 10 ° to 100 ° (5 ° to 5 ° on one side). 50 °), more preferably 30 ° to 80 ° (15 ° to 40 ° on one side). If the light diffusion half-value angle is too small, an oblique viewing angle (for example, white luminance) may be narrowed. If the light diffusion half-value angle is too large, backscattering may increase.
- the backscattering rate is preferably 0.5% or less.
- the thickness of the light diffusing element can be appropriately set according to the purpose and desired diffusion characteristics. Specifically, the thickness of the light diffusing element is preferably 4 ⁇ m to 50 ⁇ m, more preferably 4 ⁇ m to 20 ⁇ m. According to the present invention, a light diffusing element having such a very high haze as described above can be obtained despite such a very thin thickness. Furthermore, if it is such a thin thickness, even if it is bent, it will not break and can be stored in a roll shape. In addition, as will be described later, since the light diffusing element of the present invention can be formed by coating, for example, the manufacture of the light diffusing element and the bonding to the polarizing plate are continuously performed by so-called roll-to-roll. be able to.
- a roll-to-roll means the method of laminating
- the light diffusing element is suitably used for a liquid crystal display device, and particularly suitably for a collimated backlight front diffusing system.
- the light diffusing element may be provided alone as a film-like or plate-like member, or may be provided as a composite member by being attached to any appropriate base material or polarizing plate.
- An antireflection layer may be laminated on the light diffusing element.
- the matrix 10 preferably includes the resin component 11 and the ultrafine particle component 12.
- the ultrafine particle component 12 is formed by forming a refractive index modulation region 30 in the vicinity of the interface between the matrix 10 and the light diffusing fine particles 20. 11 is dispersed.
- the resin component 11 is made of any appropriate material as long as the fine uneven boundary (resulting in the refractive index modulation region) is formed.
- the resin component 11 is composed of a compound similar to the light diffusing fine particles and different from the ultrafine particle component.
- the refractive index modulation region can be satisfactorily formed in the vicinity of the interface between the matrix and the light diffusing fine particles (near the surface of the light diffusing fine particles).
- the resin component 11 is composed of a highly compatible compound in the same system as the light diffusing fine particles. Thereby, a refractive index modulation region having a desired refractive index gradient can be formed.
- the resin component is preferably composed of an organic compound, more preferably an ionizing radiation curable resin. Since the ionizing radiation curable resin is excellent in the hardness of the coating film, it is easy to compensate for the mechanical strength, which is a weak point of the ultrafine particle component described later.
- the ionizing rays include ultraviolet rays, visible light, infrared rays, and electron beams. Preferably, it is ultraviolet rays, and therefore the resin component is particularly preferably composed of an ultraviolet curable resin.
- the ultraviolet curable resin include resins formed from radical polymerization monomers or oligomers such as acrylate resins (epoxy acrylate, polyester acrylate, acrylic acrylate, ether acrylate).
- the molecular weight of the monomer component (precursor) constituting the acrylate resin is preferably 200 to 700.
- Specific examples of the monomer component (precursor) constituting the acrylate resin include pentaerythritol triacrylate (PETA: molecular weight 298), neopentyl glycol diacrylate (NPGDA: molecular weight 212), dipentaerythritol hexaacrylate (DPHA: molecular weight 632). ), Dipentaerythritol pentaacrylate (DPPA: molecular weight 578), and trimethylolpropane triacrylate (TMPTA: molecular weight 296).
- An initiator may be added to the precursor as necessary.
- the initiator examples include a UV radical generator (Irgacure 907, 127, 192, etc., manufactured by BASF Japan) and benzoyl peroxide.
- the resin component may contain another resin component in addition to the ionizing radiation curable resin.
- Another resin component may be an ionizing radiation curable resin, a thermosetting resin, or a thermoplastic resin.
- Representative examples of other resin components include aliphatic (for example, polyolefin) resins and urethane resins. When another resin component is used, the type and blending amount thereof are adjusted so that the refractive index modulation region is formed satisfactorily.
- the resin component typically satisfies the following formula (1):
- n A represents the refractive index of the resin component of the matrix
- n B represents the refractive index of the ultrafine particle component of the matrix
- n P represents the refractive index of the light diffusing fine particles.
- the resin component can also satisfy the following formula (2):
- the refractive index of the resin component is preferably 1.40 to 1.60.
- the compounding amount of the resin component is preferably 10 to 80 parts by weight, more preferably 20 to 65 parts by weight with respect to 100 parts by weight of the matrix. *
- the ultrafine particle component 12 is preferably composed of a compound of a system different from the resin component and the light diffusing fine particles described later, and more preferably composed of an inorganic compound.
- examples of preferable inorganic compounds include metal oxides and metal fluorides.
- the metal oxide include zirconium oxide (zirconia) (refractive index: 2.19), aluminum oxide (refractive index: 1.56 to 2.62), and titanium oxide (refractive index: 2.49 to 2.19). 74) and silicon oxide (refractive index: 1.25 to 1.46).
- the metal fluoride include magnesium fluoride (refractive index: 1.37) and calcium fluoride (refractive index: 1.40 to 1.43).
- metal oxides and metal fluorides have a refractive index that is difficult to be expressed by organic compounds such as ionizing radiation curable resins and thermoplastic resins in addition to low light absorption. Since the weight concentration of the ultrafine particle component becomes relatively higher as the distance from the interface increases, the refractive index can be greatly modulated. By increasing the difference in refractive index between the light diffusing fine particles and the matrix, a high haze can be realized even for a thin film, and a refractive index modulation region is formed, so that the effect of preventing backscattering is great.
- a particularly preferred inorganic compound is zirconium oxide.
- the ultrafine particle component can also satisfy the above formulas (1) and (2).
- the refractive index of the ultrafine particle component is preferably 1.40 or less or 1.60 or more, more preferably 1.40 or less or 1.70 to 2.80, and particularly preferably 1.40 or less or 2 .00 to 2.80. If the refractive index exceeds 1.40 or less than 1.60, the difference in refractive index between the light diffusing fine particles and the matrix becomes insufficient, and the light diffusing element is applied to a liquid crystal display device employing a collimated backlight front diffusion system. When used, the light from the collimated backlight cannot be sufficiently diffused and the viewing angle may be narrowed.
- the average primary particle diameter of the ultrafine particle component is preferably smaller than the average thickness L of the refractive index modulation region. More specifically, the average primary particle diameter is preferably 1/50 to 1/2, more preferably 1/25 to 1/3 with respect to the average thickness L. When the average primary particle diameter exceeds 1/2 with respect to the average thickness L, the refractive index change in the refractive index modulation region may not be substantially continuous. If it is less than 1/50, it may be difficult to form the refractive index modulation region.
- the average primary particle diameter is preferably 1 nm to 100 nm, more preferably 1 nm to 50 nm.
- the ultrafine particle component may be secondary agglomerated, and in that case, the average particle diameter (average particle diameter of the aggregate) is preferably 10 nm to 100 nm, more preferably 10 nm to 80 nm.
- the average particle diameter is preferably 10 nm to 100 nm, more preferably 10 nm to 80 nm.
- the ultrafine particle component preferably has good dispersibility with the resin component.
- “good dispersibility” means that a coating liquid obtained by mixing the resin component, the ultrafine particle component, and a volatile solvent (if necessary, a small amount of UV initiator) is applied, It means that the coating film obtained by drying and removing the solvent is transparent.
- the ultrafine particle component is surface-modified.
- the ultrafine particle component can be favorably dispersed in the resin component, and the refractive index modulation region can be favorably formed.
- Any appropriate means can be adopted as the surface modifying means as long as the effects of the present invention can be obtained.
- the surface modification is performed by applying a surface modifier to the surface of the ultrafine particle component to form a surface modifier layer.
- preferable surface modifiers include coupling agents such as silane coupling agents and titanate coupling agents, and surfactants such as fatty acid surfactants.
- the wettability between the resin component and the ultrafine particle component is improved, the interface between the resin component and the ultrafine particle component is stabilized, and the ultrafine particle component is improved in the resin component.
- the refractive index modulation region can be favorably formed while being dispersed.
- the blending amount of the ultrafine particle component is preferably 15 to 80 parts by weight, more preferably 20 to 70 parts by weight with respect to 100 parts by weight of the matrix.
- the light diffusing fine particle 20 is also composed of any appropriate material as long as the fine uneven boundary (resulting in the refractive index modulation region) is formed well.
- the light diffusing fine particles 20 are composed of a compound similar to the resin component of the matrix.
- the ionizing radiation curable resin constituting the resin component of the matrix is an acrylate resin
- the light diffusing fine particles are also preferably composed of an acrylate resin.
- the acrylate constituting the light diffusing fine particles The base resin is preferably polymethyl methacrylate (PMMA), polymethyl acrylate (PMA), and a copolymer thereof, and a cross-linked product thereof.
- PMMA polymethyl methacrylate
- PMA polymethyl acrylate
- the copolymer component with PMMA and PMA include polyurethane, polystyrene (PS), and melamine resin.
- the light diffusing fine particles are composed of PMMA. This is because the relationship between the refractive index and thermodynamic properties of the matrix resin component and ultrafine particle component is appropriate.
- the light diffusing fine particles have a cross-linked structure (three-dimensional network structure).
- crosslinking degree the degree of freedom of the polymer molecules constituting the fine particles on the surface of the light diffusing fine particles can be controlled, so that the dispersion state of the ultrafine particle component can be controlled, As a result, the refractive index modulation region can be formed by a fine uneven boundary having a desired shape.
- the degree of swelling of the light diffusing fine particles with respect to the resin component precursor (which may contain a solvent) at the time of applying the coating liquid described later is preferably 100% to 200%.
- the “swelling degree” is an index of the degree of crosslinking, and refers to the ratio of the average particle diameter of the swollen particles to the average particle diameter of the particles before swelling.
- the light diffusing fine particles have an average particle size of preferably 1.0 ⁇ m to 5.0 ⁇ m, more preferably 1.0 ⁇ m to 4.0 ⁇ m.
- the average particle diameter of the light diffusing fine particles is preferably 1 ⁇ 2 or less (for example, 1 ⁇ 2 to 1/20) of the thickness of the light diffusing element. If the average particle diameter has such a ratio with respect to the thickness of the light diffusing element, a plurality of light diffusing fine particles can be arranged in the thickness direction of the light diffusing element, so that incident light passes through the light diffusing element. In the meantime, the light can be diffused multiple times, and as a result, sufficient light diffusibility can be obtained.
- the standard deviation of the weight average particle size distribution of the light diffusing fine particles is preferably 1.0 ⁇ m or less, more preferably 0.5 ⁇ m or less. If a large number of light diffusing fine particles having a small particle size with respect to the weight average particle size are mixed, the diffusibility may be excessively increased and the backscattering may not be suppressed satisfactorily. If a large number of light diffusing fine particles having a large particle diameter with respect to the weight average particle diameter are mixed, a plurality of light diffusing elements cannot be arranged in the thickness direction of the light diffusing element, and multiple diffusion may not be obtained. , The light diffusibility may be insufficient.
- any appropriate shape can be adopted depending on the purpose. Specific examples include a true sphere shape, a flake shape, a plate shape, an elliptic sphere shape, and an indefinite shape. In many cases, spherical fine particles can be used as the light diffusing fine particles.
- the light diffusing fine particles can also satisfy the above formulas (1) and (2).
- the refractive index of the light diffusing fine particles is preferably 1.30 to 1.70, more preferably 1.40 to 1.60.
- the blending amount of the light diffusing fine particles is preferably 10 to 100 parts by weight, more preferably 10 to 40 parts by weight, and further preferably 10 to 35 parts by weight with respect to 100 parts by weight of the matrix. Part.
- a light diffusing element having a very excellent light diffusibility can be obtained by incorporating light diffusing fine particles having an average particle diameter in the above preferred range with such a blending amount.
- the manufacturing method of the light diffusing element of this embodiment is a coating liquid in which a resin component of a matrix or a precursor thereof, an ultrafine particle component, and a light diffusing fine particle are dissolved or dispersed in a volatile solvent. And a step (referred to as Step A) for applying the coating liquid to the substrate, and a step (referred to as Step B) for drying the coating liquid applied to the substrate.
- the resin component or precursor thereof, the ultrafine particle component, and the light diffusing fine particles are as described in the above sections A-2-1, A-2-2, and A-3, respectively.
- the coating liquid is a dispersion in which ultrafine particle components and light diffusing fine particles are dispersed in a precursor and a volatile solvent.
- any appropriate means for example, ultrasonic treatment, dispersion treatment with a stirrer can be employed.
- any appropriate solvent can be adopted as long as the above components can be dissolved or uniformly dispersed.
- the volatile solvent include ethyl acetate, butyl acetate, isopropyl acetate, 2-butanone (methyl ethyl ketone), methyl isobutyl ketone, cyclopentanone, toluene, isopropyl alcohol, n-butanol, cyclopentane, and water.
- the coating liquid may further contain any appropriate additive depending on the purpose.
- a dispersant in order to disperse the ultrafine particle component satisfactorily, a dispersant can be suitably used.
- the additive include an ultraviolet absorber, a leveling agent, and an antifoaming agent.
- the blending amount of each component in the coating solution is as described in the above sections A-2 to A-3.
- the solid content concentration of the coating solution can be adjusted to be preferably about 10% by weight to 70% by weight. If it is such solid content concentration, the coating liquid which has a viscosity with easy coating can be obtained.
- any appropriate film can be adopted as long as the effects of the present invention can be obtained.
- Specific examples include a triacetyl cellulose (TAC) film, a polyethylene terephthalate (PET) film, a polypropylene (PP) film, a nylon film, an acrylic film, and a lactone-modified acrylic film.
- the base material may be subjected to surface modification such as easy adhesion treatment, and may contain additives such as a lubricant, an antistatic agent, and an ultraviolet absorber.
- the base material may function as a protective layer in the polarizing plate with a light diffusing element described later.
- a method for applying the coating liquid to the base material a method using any appropriate coater can be employed.
- the coater include a bar coater, a reverse coater, a kiss coater, a gravure coater, a die coater, and a comma coater.
- Process B Any appropriate method can be adopted as a method for drying the coating solution. Specific examples include natural drying, heat drying, and vacuum drying. Heat drying is preferable.
- the heating temperature is, for example, 60 ° C. to 150 ° C., and the heating time is, for example, 30 seconds to 5 minutes.
- the manufacturing method further includes a step (step C) of polymerizing the precursor after the coating step.
- the polymerization method any appropriate method can be adopted depending on the type of the resin component (and hence its precursor).
- the resin component is an ionizing radiation curable resin
- the precursor is polymerized by irradiating the ionizing radiation.
- ultraviolet rays are used as ionizing rays
- the integrated light quantity is preferably 50 mJ / cm 2 to 1000 mJ / cm 2 .
- the transmittance of the ionizing rays to the light diffusing fine particles is preferably 70% or more, more preferably 80% or more.
- the precursor is polymerized by heating.
- the heating temperature and the heating time can be appropriately set according to the type of the resin component.
- the polymerization is performed by irradiating with ionizing radiation. With ionizing ray irradiation, the coating film can be cured while the refractive index modulation region is well maintained, so that a light diffusing element having good diffusion characteristics can be produced.
- two regions having different refractive indexes in the vicinity of the interface with the light diffusing fine particles form a fine uneven-shaped boundary, thereby forming the matrix 10 in which the refractive index modulation region 30 is formed. Is done.
- the polymerization step (step C) may be performed before the drying step (step B) or after step B.
- the light diffusing element as shown in FIGS. 1A and 1B is formed on the substrate.
- the manufacturing method of the light diffusing element of the present embodiment can include any appropriate process, process and / or operation at any appropriate time in addition to the above-mentioned processes A to C.
- the type of such a process and the time when such a process is performed can be appropriately set according to the purpose.
- the light diffusing element as described in the above sections A-1 to A-3 is formed on the substrate.
- FIG. 6 is a schematic cross-sectional view of a light diffusing element according to another embodiment of the present invention.
- a light diffusing element 100 ′ in FIG. 6 includes a matrix 10 and light diffusing fine particles 20 dispersed in the matrix 10.
- the outer periphery of the light diffusing fine particles 20 is formed in a fine concavo-convex shape, and a fine concavo-convex shape and a spherical shell-like boundary are formed by the outer portion, and the boundary constitutes the refractive index modulation region 30.
- the fine concavo-convex shape and the spherical shell-like boundary are formed by the concavo-convex on the surface of the light diffusing fine particles.
- the irregularities on the surface of the light diffusing fine particles can be formed by any appropriate means.
- a fine uneven shape can be formed by treating the surface of the light diffusing fine particles with an appropriate solvent.
- the solvent used for the surface treatment include ketone solvents such as methyl ethyl ketone (MEK) and methyl isobutyl ketone (MIBK), and ester solvents such as ethyl acetate and butyl acetate.
- the matrix 10 can be made of, for example, a resin as described in the above section A-2-1 with respect to a resin component in a form using an ultrafine particle component.
- the matrix 10 may or may not contain an ultrafine particle component.
- the fine irregular shape and the spherical shell boundary may be formed only by the irregularities on the surface of the light diffusing fine particles, and the combination of the irregularities on the surface of the light diffusing fine particles and the gradient of the dispersion concentration of the ultrafine particle component. May be formed.
- the refractive index modulation region 30 the refractive index preferably changes substantially continuously.
- the light diffusing fine particles correspond to the first region
- the matrix corresponds to the second region.
- a light diffusing element (not shown) according to still another embodiment of the present invention includes a matrix and light diffusing fine particles dispersed in the matrix.
- the light diffusing fine particles are refractive index gradient particles (for example, GRIN fine particles) whose refractive index changes from the central portion toward the outside, and the refractive index gradient portion forms a refractive index modulation region.
- the refractive index gradient particle is a polymer particle having a central part and a surface layer part covering the central part. Specific examples of polymers constituting such polymer particles include vinyl polymers, (meth) acrylic polymers, and styrene polymers. By properly selecting the polymer, the refractive index gradient can be controlled.
- Such polymer particles use, for example, a plurality of monomers having different refractive indexes, and in the copolymerization thereof, the refractive index is changed stepwise or continuously by changing the amount of the monomer as the polymerization proceeds. be able to. Details of such polymer particles and the production method thereof are described in, for example, Japanese Patent Application Laid-Open No. 2006-227279, and the description thereof is incorporated herein by reference.
- the light diffusing element of the present invention may be peeled off from the base material and used as a single member, or may be used as a light diffusing element with a base material. It may be used as a polarizing plate with a light diffusing element) or may be used as a composite member (for example, a polarizing plate with a light diffusing element) by being attached to a polarizing plate or the like together with the base material.
- the base material is attached to a polarizing plate or the like and used as a composite member (for example, a polarizing plate with a light diffusing element)
- the base material can function as a protective layer for the polarizing plate.
- the light diffusing element of the present invention is not limited to the viewing side diffusing element of the liquid crystal display device adopting the collimated backlight front diffusing system described above. , LED) can be used as a diffusion member.
- the present invention is not limited to these embodiments, and the first region having the first refractive index and the second region having the second refractive index. And the first region and the second region are fine uneven and form a spherical shell-like boundary.
- FIG. 7 is a schematic cross-sectional view of a polarizing plate with a light diffusing element according to a preferred embodiment of the present invention.
- the polarizing plate with a light diffusing element 200 includes a light diffusing element 100 and a polarizer 110.
- the light diffusing element 100 is the light diffusing element of the present invention described in the above items A-1 to A-5.
- the light diffusing element 100 is disposed so as to be the most visible side when the polarizing plate with the light diffusing element is disposed on the viewing side of the liquid crystal display device.
- a low reflection layer or an antireflection treatment layer is disposed on the viewing side of the light diffusing element 100 (not shown).
- the polarizing plate with a light diffusing element 200 has protective layers 120 and 130 on both sides of the polarizer.
- the light diffusing element, the polarizer and the protective layer are attached via any appropriate adhesive layer or pressure-sensitive adhesive layer. At least one of the protective layers 120 and 130 may be omitted depending on the purpose, the configuration of the polarizing plate, and the configuration of the liquid crystal display device.
- the protective layer 120 can be omitted.
- the polarizing plate with a light diffusing element of the present invention can be particularly suitably used as a viewing side polarizing plate in a liquid crystal display device employing a collimated backlight front diffusion system.
- Polarizer Any appropriate polarizer may be adopted as the polarizer 110 depending on the purpose.
- dichroic substances such as iodine and dichroic dyes are adsorbed on hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and ethylene / vinyl acetate copolymer partially saponified films.
- polyene-based oriented films such as a uniaxially stretched product, a polyvinyl alcohol dehydrated product and a polyvinyl chloride dehydrochlorinated product.
- a polarizer obtained by adsorbing a dichroic substance such as iodine on a polyvinyl alcohol film and uniaxially stretching is particularly preferable because of its high polarization dichroic ratio.
- the thickness of these polarizers is not particularly limited, but is generally about 1 to 80 ⁇ m.
- a polarizer uniaxially stretched by adsorbing iodine to a polyvinyl alcohol film can be produced, for example, by dyeing polyvinyl alcohol in an aqueous iodine solution and stretching it 3 to 7 times the original length. . If necessary, it may contain boric acid, zinc sulfate, zinc chloride or the like, or may be immersed in an aqueous solution such as potassium iodide. Further, if necessary, the polyvinyl alcohol film may be immersed in water and washed before dyeing.
- Stretching may be performed after dyeing with iodine, may be performed while dyeing, or may be dyed with iodine after stretching.
- the film can be stretched in an aqueous solution of boric acid or potassium iodide or in a water bath.
- the protective layers 120 and 130 are formed of any appropriate film that can be used as a protective layer of a polarizing plate.
- the material as the main component of the film include cellulose resins such as triacetyl cellulose (TAC), polyester-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, polyimide-based, polyethersulfone-based, and polysulfone-based materials.
- transparent resins such as polystyrene, polynorbornene, polyolefin, (meth) acryl, and acetate.
- thermosetting resins such as (meth) acrylic, urethane-based, (meth) acrylurethane-based, epoxy-based, and silicone-based or ultraviolet curable resins are also included.
- a glassy polymer such as a siloxane polymer is also included.
- a polymer film described in JP-A-2001-343529 (WO01 / 37007) can also be used.
- a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and nitrile group in the side chain for example, a resin composition having an alternating copolymer of isobutene and N-methylmaleimide and an acrylonitrile / styrene copolymer can be mentioned.
- the polymer film can be, for example, an extruded product of the resin composition.
- the protective layer (inner protective layer) 130 is preferably optically isotropic.
- the thickness direction retardation Rth (550) of the inner protective layer is preferably ⁇ 20 nm to +20 nm, more preferably ⁇ 10 nm to +10 nm, particularly preferably ⁇ 6 nm to +6 nm, and most preferably ⁇ 3 nm to +3 nm. It is.
- the in-plane retardation Re (550) of the inner protective layer is preferably 0 nm or more and 10 nm or less, more preferably 0 nm or more and 6 nm or less, and particularly preferably 0 nm or more and 3 nm or less. Details of the film that can form such an optically isotropic protective layer are described in Japanese Patent Application Laid-Open No. 2008-180961, which description is incorporated herein by reference.
- FIG. 8 An example of a method for producing a polarizing plate with a light diffusing element of the present invention will be briefly described.
- reference numerals 111 and 112 denote rolls for winding the polarizing plate and the light diffusing element / substrate laminate, respectively, and reference numeral 122 denotes a transport roll.
- a polarizing plate (protective layer 130 / polarizer 110 / protective layer 120) and a laminate of the light diffusing element 100 / base material 101 are sent out in the direction of the arrow, and are bonded together with their respective longitudinal directions aligned. .
- the light diffusing element 100 and the protective layer 120 of the polarizing plate are bonded so as to be adjacent to each other.
- the polarizing plate 200 with a light-diffusion element as shown in FIG. 7 can be obtained by peeling the base material 101 as needed.
- a polarizing plate (protective layer 130 / polarizer 110) and a laminate of the light diffusing element 100 / base material 101 are bonded together so that the base material 101 and the polarizer 110 are adjacent to each other.
- a polarizing plate with a light diffusing element that functions as a protective layer can also be produced.
- so-called roll-to-roll can be employed, so that the polarizing plate with a light diffusing element can be manufactured with very high manufacturing efficiency. Further, since this roll-to-roll process can be carried out continuously from the manufacturing process of the light diffusing element described in the above section A-4, if such a procedure is adopted, the polarizing plate with the light diffusing element is used. The production efficiency can be further improved.
- FIG. 9 is a schematic cross-sectional view of a liquid crystal display device according to a preferred embodiment of the present invention.
- the liquid crystal display device 500 includes a liquid crystal cell 510, polarizing plates 520 and 530 disposed on both sides of the liquid crystal cell, a backlight unit 540 provided outside the polarizing plate 530, and the outside (viewing side) of the polarizing plate 520.
- the light diffusing element 100 is provided. Any appropriate optical compensation plate (retardation plate) may be disposed between the liquid crystal cell 510 and the polarizing plates 520 and / or 530 depending on the purpose.
- the liquid crystal cell 510 includes a pair of substrates (typically, glass substrates) 511 and 512 and a liquid crystal layer 513 that includes liquid crystal serving as a display medium and is disposed between the substrates 511 and 512.
- the light diffusing element 100 is the light diffusing element of the present invention described in the above sections A-1 to A-5.
- the polarizing plate with a light diffusing element of the present invention described in the above section B may be disposed.
- the light diffusing element transmits and diffuses light that has passed through the liquid crystal cell (typically, collimated light as described below).
- the backlight unit 540 is a parallel light source device that emits collimated light toward the liquid crystal cell 510.
- the backlight unit may have any suitable configuration that can emit collimated light.
- the backlight unit includes a light source and a condensing element that collimates light emitted from the light source (none of which is shown).
- any appropriate condensing element capable of collimating light emitted from the light source can be employed as the condensing element. If the light source itself can emit collimated light, the condensing element can be omitted.
- the backlight unit includes, for example, the following: (1) A light shielding layer on a portion other than the focal point of the lens on the flat surface side of the lenticular lens or the bullet-type lens.
- the light guide plate and a structure having a convex surface formed on the light guide plate side and a variable angle prism disposed on the liquid crystal cell side of the light guide plate in this configuration, an anisotropic diffusion element is further used as necessary.
- Japanese Patent No. 3442247 (3) A louver layer in which a light-absorbing resin and a transparent resin are alternately formed in a stripe shape is provided between a backlight and a backlight-side polarizing plate. (4) Configuration using a bullet-type LED as a light source (for example, JP-A-6-130255); (5) Fresnel lens and, if necessary, A configuration using a diffusion plate (for example, JP-A-1-126627).
- a bullet-type LED for example, JP-A-6-130255
- Fresnel lens and, if necessary, A configuration using a diffusion plate for example, JP-A-1-126627.
- FIG. 10A is a schematic diagram of the parallel light source device of (5) above.
- the parallel light source device 7 includes a light source 1, a projection lens 2, a lenticular lens 3, a reflecting plate 4, and a Fresnel lens 5.
- the light beam emitted from the light source 1 passes through the projection lens 2 and the lenticular lens 3 and is reflected by the mirror surface of the reflecting plate 4.
- the reflected light beam passes through the Fresnel lens 5 and is irradiated as parallel light.
- FIG. 10B shows a configuration in which the diffusion plate 6 is disposed on the liquid crystal cell side of the Fresnel lens 5.
- the light beam emitted from the light source 1 passes through the projection lens 2 and the lenticular lens 3 and is reflected by the mirror surface of the reflecting plate 4.
- the reflected light beam passes through the Fresnel lens 5 and is irradiated as parallel light.
- the irradiated parallel light further passes through the diffusion plate 6 and is diffusely irradiated.
- the diffusibility of the diffusion plate is preferably 2% to 92%, more preferably 30% to 80% as haze.
- the diffusivity of the diffusing plate is preferably 1 ° to 30 °, more preferably 5 ° to 20 °, as a light diffusion half-value angle.
- the diffusion plate may have a straight transmission component, and the half-value angle of light diffusion in that case is preferably 1 to 30 ° for the diffused light excluding the straight transmission component.
- any appropriate plate can be used as the diffusion plate having such properties. Specifically, a surface uneven diffusion film or an internal diffusion film in which a binder containing fine particles is coated on a transparent substrate film; a phase-separated extruded sheet in which an incompatible resin is blended and molded; an embossing roll on the surface An embossed sheet in which a concavo-convex pattern is formed; an integrated structure of a lens and a diffuser plate in which a fine concavo-convex shape is given to one or both surfaces of a Fresnel lens by applying a binder containing fine particles.
- the diffusion performance of the backlight unit 540 has a half-value angle of preferably 1 ° to 40 °, more preferably 2 ° to 30 °, and further preferably 2.5 ° to 20 °. If the half-value angle is less than 1 °, glare (glare) may not be reduced even if the diffusion performance of the light diffusing element is improved. When the half-value angle exceeds 40 °, oblique light that is not completely compensated for black display is generated, which is diffused to the front by the light diffusing element, which may increase the black luminance and reduce the front contrast ratio. is there.
- the half-value angle refers to the full width at half maximum of the angle at which the luminance is halved when the angle is shifted from the direction in which the luminance is maximum, as shown in FIG.
- the half-value angle is less than 1 °, the same effect as when it is 1 ° or more may be obtained as long as the bottom of diffusion is widened.
- the average diffusion angle ⁇ d represented by the following formula is 1 ° or more, glare (glare) can be reduced by a combination with a light diffusion element that performs multiple diffusion.
- the liquid crystal layer 513 includes liquid crystal molecules vertically aligned during black display.
- a driving mode of a liquid crystal cell having such a liquid crystal layer for example, an MVA (multi-domain vertical alignment) mode, a PVA (pattern VA) mode, a TN (twisted nematic) mode, an ECB (electric field control birefringence) mode, An OCB (Optical Compensation Bend) mode is exemplified.
- Thickness of the light diffusing element The total thickness of the base material and the light diffusing element is measured with a microgauge thickness meter (manufactured by Mitutoyo Corporation), and the thickness of the light diffusing element is subtracted from the total thickness. was calculated.
- TEM transmission electron microscope
- the laminate of the light diffusing element and the substrate obtained in Examples and Comparative Examples was cooled with liquid nitrogen, sliced to a thickness of 0.1 ⁇ m with a microtome, and used as a measurement sample. The state of fine particles in the light diffusing element portion of the measurement sample and the state of the interface between the fine particles and the matrix were observed.
- gold particles with a diameter of 5 nm were attached to the measurement sample obtained above as a marker for correcting the photographing position, and continuous inclined TEM images (121 images) were obtained every 1 ° from ⁇ 60 ° to 60 °. I took a picture.
- the 121 TEM images were subjected to position correction by the Fiducial Marker method to reconstruct a three-dimensional image.
- IMOD 3.9.3 1 was used as reconstruction software, and Mercury Computer Systems, Amira was used as display software.
- the interface (real interface) between the light diffusing fine particles and the matrix is extracted from the three-dimensional reconstructed image obtained as described above, and fitting with an approximate curved surface is performed on the real interface. From the distance between the convex portions projecting 30 nm or more and the average height of the convex portions, the average pitch and the average height of the concave and convex portions at the boundary of the fine concave and convex portions were obtained. In addition, the following formula was used for the fitting approximate curve.
- the diffusion angle at which the luminance is half of the maximum value of the light diffusion luminance excluding the straight transmitted light is measured on both sides of the diffusion, and the sum of the angles on both sides (angle A + angle A ′ in FIG. 12) is the light diffusion half value. It was a corner.
- the laminated body of the light diffusing element and the base material obtained in the examples and comparative examples was placed on a black acrylic plate (trade name “SUMIPEX” (registered trademark) manufactured by Sumitomo Chemical Co., Ltd.) through a transparent adhesive. ) And a thickness of 2 mm) to obtain a measurement sample.
- the integrated reflectance of this measurement sample was measured with a spectrophotometer (trade name “U4100”, manufactured by Hitachi Keiki Co., Ltd.).
- a coating liquid obtained by removing fine particles from the light diffusing element coating liquid a laminate of a substrate and a transparent coating layer was prepared as a control sample, and the integrated reflectance ( That is, the surface reflectance was measured.
- the backscattering rate of the light diffusing element was calculated by subtracting the integrated reflectance (surface reflectance) of the control sample from the integrated reflectance of the measurement sample.
- Example 1 Production of light diffusing element> Resin for hard coat containing 62% of zirconia nanoparticles (average primary particle size 10 nm, average particle size 60 nm, refractive index 2.19) as an ultrafine particle component (trade name “OPSTAR KZ6661” (MEK / MIBK)) 100 parts of a 50% methyl ethyl ketone (MEK) solution of pentaerythritol triacrylate (trade name “Biscoat # 300” manufactured by Osaka Organic Chemical Industry Co., Ltd., refractive index 1.52) as a precursor of the resin component 11 parts, 0.5 parts of photopolymerization initiator (BASF Japan, trade name “Irgacure 907”), 0.5 parts of leveling agent (DIC, trade name “GRANDIC PC 4100”), and light Polymethyl methacrylate (PMMA) fine particles as diffusible fine particles (manufactured by Sekisui Plastics Co., Ltd., trade name “SAX-10
- This mixture was stirred for 30 minutes using a stirrer (manufactured by Asada Tekko Co., Ltd., trade name “DESPA”) for dispersion treatment to prepare a coating liquid in which the above components were uniformly dispersed.
- the solid content concentration of this coating solution was 55%.
- DESPA trade name “DESPA”
- the difference between the average refractive index n M of the matrix and the refractive index n P of the light diffusing fine particles in the obtained light diffusing element was 0.12 (n M > n P ).
- the obtained light diffusing element was subjected to the evaluations (1) to (5) above. The results are shown in Table 1 together with the results of Examples 2 to 10 and Comparative Examples 1 to 3 described later. Furthermore, the obtained light diffusing element was observed with TEM. The results are shown in FIG. A three-dimensional image was reconstructed from the TEM image, and the three-dimensional reconstructed image was binarized. As a result, it was confirmed that a fine uneven boundary as shown in FIGS. 2B to 2E was formed.
- the relationship between the distance from the surface of the light diffusing fine particles and the dispersion concentration (existence ratio) of the ultrafine particle component was calculated from the TEM image. As a result, as shown in FIG. 3, it was confirmed that a gradient of the dispersion concentration of the ultrafine particle component was formed.
- Example 2 Production of light diffusing element> Example except that polymethyl methacrylate (PMMA) fine particles (manufactured by Sekisui Plastics Co., Ltd., trade name “XX-131AA”, average particle size 2.5 ⁇ m, refractive index 1.495) were used as light diffusing fine particles.
- PMMA polymethyl methacrylate
- XX-131AA average particle size 2.5 ⁇ m
- refractive index 1.495 refractive index 1.95
- Example 3 Production of light diffusing element> Example 1 except that polymethyl methacrylate (PMMA) fine particles (manufactured by Negami Kogyo Co., Ltd., trade name “Art Pearl J4P”, average particle size 2.5 ⁇ m, refractive index 1.495) were used as light diffusing fine particles.
- PMMA polymethyl methacrylate
- Art Pearl J4P average particle size 2.5 ⁇ m, refractive index 1.495
- Example 4 Production of light diffusing element> 100 parts of hard coat resin (manufactured by JSR, containing MEK / PGME) containing 60% titania nanoparticles (average primary particle size 10 nm, average particle size 60 nm, refractive index 2.3) were used as the ultrafine particle component. A light diffusing element having a thickness of 11 ⁇ m was obtained in the same manner as Example 3 except for the above. The obtained light diffusing element was subjected to the same evaluation as in Example 1. The results are shown in Table 1 above.
- Example 5 Production of light diffusing element> As in Example 3, except that 11 parts of a 50% MEK solution of hydroxyethylacrylamide (trade name “HEAA”, refractive index 1.52) manufactured by Kojin Co., Ltd. was used as a precursor of the resin component. An 11 ⁇ m light diffusing element was obtained. The obtained light diffusing element was subjected to the same evaluation as in Example 1. The results are shown in Table 1 above.
- HEAA hydroxyethylacrylamide
- Example 6 Production of light diffusing element> A thickness of 10 ⁇ m was obtained in the same manner as in Example 3 except that 11 parts of 50% MEK solution of acryloylmorpholine (trade name “ACMO”, refractive index 1.52) manufactured by Kojin Co., Ltd. was used as the precursor of the resin component. The light diffusing element was obtained. The obtained light diffusing element was subjected to the same evaluation as in Example 1. The results are shown in Table 1 above.
- Example 7 Production of light diffusing element> Fine particles obtained by adding hydrophilic groups to polymethyl methacrylate (PMMA) as light diffusing fine particles (manufactured by Sekisui Plastics, trade name “XX-157-AA”, average particle size 2.5 ⁇ m, refractive index 1.495) 15 A light diffusing element having a thickness of 10 ⁇ m was obtained in the same manner as in Example 1 except that the part was used. The obtained light diffusing element was subjected to the same evaluation as in Example 1. The results are shown in Table 1 above.
- PMMA polymethyl methacrylate
- Example 8 Production of light diffusing element> Copolymer fine particles of polymethyl methacrylate (PMMA) and polystyrene (PS) as light diffusing fine particles (manufactured by Sekisui Plastics, trade name “XX-164-AA”, average particle size 2.5 ⁇ m, refractive index 1.495) )
- PMMA polymethyl methacrylate
- PS polystyrene
- a light diffusing element having a thickness of 10 ⁇ m was obtained in the same manner as in Example 1 except that 15 parts were used.
- the obtained light diffusing element was subjected to the same evaluation as in Example 1. The results are shown in Table 1 above.
- Example 9 Production of light diffusing element> A light diffusing element having a thickness of 9 ⁇ m was obtained in the same manner as in Example 1 except that the content of the zirconia nanoparticles as the ultrafine particle component in the hard coat resin was 25%. The obtained light diffusing element was subjected to the same evaluation as in Example 1. The results are shown in Table 1 above.
- Example 10 Production of light diffusing element> To 100 parts of hard coat resin (trade name “Z7540” manufactured by JSR Corporation) containing 30% of silica nanoparticles (average primary particle diameter 10 nm, average particle diameter 40 nm, refractive index 1.49) as an ultrafine particle component, 15 parts of polystyrene (PS) fine particles (manufactured by Soken Chemical Co., Ltd., trade name “SX-350H”, average particle size 3.5 ⁇ m, refractive index 1.595) were added as diffusible fine particles, and the surface of the PS fine particles A 10 ⁇ m-thick light diffusing element was obtained in the same manner as in Example 1 except that this was treated with MEK to form a fine concavo-convex shape (PS fine particles had a shape like gold flat sugar).
- PS polystyrene
- FIG. 14 shows a TEM image in the vicinity of the light diffusing fine particles of the obtained light diffusing element. From the TEM image, it was confirmed that a fine uneven boundary was formed.
- Example 2 A light diffusing element having a thickness of 10 ⁇ m was obtained in the same manner as in Example 1 except that a hard coat resin not containing zirconia nanoparticles as an ultrafine particle component was used. The obtained light diffusing element was subjected to the same evaluation as in Example 1. The results are shown in Table 1 above. Furthermore, FIG. 15 shows a TEM image in the vicinity of the light diffusing fine particles of the obtained light diffusing element. From this TEM image, it can be seen that the interface between the light diffusing fine particles and the matrix is clear, and the fine uneven boundary is not formed.
- Example 3 A light diffusing element having a thickness of 10 ⁇ m was prepared in the same manner as in Example 1, except that 15 parts of silica-modified methyl (manufactured by Nippon Shokubai, trade name “Seahoster KE-250”) was used as the light diffusing fine particles. Obtained. The obtained light diffusing element was subjected to the same evaluation as in Example 1. The results are shown in Table 1 above.
- Example 11 Production of liquid crystal display device>
- the liquid crystal cell was taken out from a commercially available liquid crystal television (manufactured by SONY, BRAVIA 20 type, trade name “KDL20J3000”) having a multi-domain VA mode liquid crystal cell.
- Commercially available polarizing plates (trade name “NPF-SEG1423DU” manufactured by Nitto Denko Corporation) were bonded to both sides of the liquid crystal cell so that the absorption axes of the respective polarizers were orthogonal to each other.
- the absorption axis direction of the polarizer of the backlight side polarizing plate is the vertical direction (90 ° with respect to the long side direction of the liquid crystal panel), and the absorption axis direction of the polarizer of the viewing side polarizing plate is the horizontal direction. Bonding was performed so as to be (0 ° with respect to the long side direction of the liquid crystal panel). Further, the light diffusing element of Example 1 was transferred from the base material and bonded to the outside of the viewing side polarizing plate to produce a liquid crystal panel.
- a lenticular lens pattern was melt-heat transferred onto one side of a PMMA sheet using a transfer roll.
- An aluminum pattern is deposited on the surface (smooth surface) opposite to the surface on which the lens pattern is formed so that light is transmitted only through the focal point of the lens, and the area ratio of the opening is 7% (the area ratio of the reflection section is 93). %) Of the reflective layer.
- a cold cathode fluorescent lamp manufactured by Sony Corporation, BRAVIA20J CCFL
- a condensing element was attached to the light source to produce a parallel light source device (backlight unit) that emits collimated light.
- the above backlight unit was incorporated into the above liquid crystal panel to produce a liquid crystal display device of a collimated backlight front diffusion system.
- white display and black display were performed in a dark place, and the display state was visually observed.
- the black display in the bright place was black and the brightness of the white display in the dark place was high.
- Example 4 A liquid crystal display device was produced in the same manner as in Example 11 except that the light diffusing element of Comparative Example 1 was used. About the obtained liquid crystal display device, white display and black display were performed in a dark place, and the display state was visually observed. As a result, when viewed from an oblique direction, the brightness of the white display in the dark place was high, but the black display in the bright place looked blurred.
- Example 5 A liquid crystal display device was produced in the same manner as in Example 11 except that the light diffusing element of Comparative Example 2 was used. About the obtained liquid crystal display device, white display and black display were performed in a dark place, and the display state was visually observed. As a result, when viewed from an oblique direction, the brightness of the white display in the dark place was high, but the black display in the bright place looked blurred.
- Example 12 Production of liquid crystal display device> A liquid crystal display device was produced in the same manner as in Example 11 except that the light diffusing element of Example 2 was used instead of the light diffusing element of Example 1. About the obtained liquid crystal display device, white display and black display were performed in a dark place, and the display state was visually observed. As a result, when viewed from an oblique direction, the black display in the bright place was black and the brightness of the white display in the dark place was high.
- Example 13 Production of liquid crystal display device> A liquid crystal display device was produced in the same manner as in Example 11 except that the light diffusing element of Example 3 was used instead of the light diffusing element of Example 1. About the obtained liquid crystal display device, white display and black display were performed in a dark place, and the display state was visually observed. As a result, when viewed from an oblique direction, the black display in the bright place was black and the brightness of the white display in the dark place was high.
- the light diffusing element of the example in which the fine uneven boundary was formed had high haze and low backscattering rate.
- the light diffusing element of the example has a thickness of 9 ⁇ m to 11 ⁇ m and is very thin. Furthermore, when the light diffusing element of the example was used as a front diffusing element of a liquid crystal display device of a collimated backlight front diffusing system, it exhibited extremely excellent display characteristics.
- the light diffusing element of Comparative Example 1 in which the fine uneven boundary is not formed has a high haze but a high backscattering rate, and the light diffusing element of Comparative Example 2 has a low backscattering rate but a very insufficient haze. there were.
- the light diffusing element of the comparative example was used as a front diffusing element of a liquid crystal display device of a collimated backlight front diffusing system, there was a problem that black display in a bright place was blurred.
- the light diffusing element and the polarizing plate with a light diffusing element of the present invention are suitably used for a viewing side member of a liquid crystal display device, a backlight member of a liquid crystal display device, and a diffusing member for a lighting device (for example, organic EL, LED).
- a lighting device for example, organic EL, LED
- it can be suitably used as a front diffusion element of a liquid crystal display device of a collimated backlight front diffusion system.
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Nonlinear Science (AREA)
- Chemical & Material Sciences (AREA)
- Mathematical Physics (AREA)
- Crystallography & Structural Chemistry (AREA)
- Dispersion Chemistry (AREA)
- Optical Elements Other Than Lenses (AREA)
- Polarising Elements (AREA)
- Liquid Crystal (AREA)
Abstract
Description
本発明の別の実施形態による光拡散素子は、マトリクスと該マトリクス中に分散された光拡散性微粒子とを有し、該マトリクスと該光拡散性微粒子との界面またはその近傍にて屈折率の異なる2つの領域が微細凹凸状でかつ球殻状の境界を形成している。
好ましい実施形態においては、上記マトリクスは樹脂成分および超微粒子成分を含み、上記微細凹凸状でかつ球殻状の境界が、該マトリクス中の該超微粒子成分が分散している領域と分散していない領域とにより形成されている。
好ましい実施形態においては、上記微細凹凸状でかつ球殻状の境界は、上記光拡散性微粒子の表面の凹凸により形成されている。
好ましい実施形態においては、上記超微粒子成分の平均1次粒子径は1nm~100nmである。
好ましい実施形態においては、上記光拡散素子は、ヘイズが90%~99.9%である。
好ましい実施形態においては、上記光拡散素子は、厚みが4μm~50μmである。
好ましい実施形態においては、上記光拡散素子は、光拡散半値角が10°~150°である。
本発明の別の局面によれば、光拡散素子付偏光板が提供される。この光拡散素子付偏光板は、上記の光拡散素子と偏光子とを有する。
本発明のさらに別の局面によれば、液晶表示装置が提供される。この液晶表示装置は、液晶セルと、該液晶セルに向かってコリメート光を出射する平行光光源装置と、該液晶セルを通過したコリメート光を透過および拡散させる、上記の光拡散素子と、を備える。
A-1.全体構成
本発明の光拡散素子は、第1の屈折率を有する第1の領域と第2の屈折率を有する第2の領域とを有する。本発明の光拡散素子は、第1の領域と第2の領域との屈折率差により、光拡散機能を発現する。本発明においては、第1の領域および第2の領域が微細凹凸状でかつ球殻状の境界を形成している。したがって、本発明の光拡散素子においては、外見的には、微細凹凸状でかつ球殻状の境界で包囲された第1の領域が、第2の領域に分散した状態となっている。当該境界の微細凹凸のサイズは、好ましくは光の波長以下である。すなわち、屈折率の異なる第1の領域と第2の領域との間に光の波長以下のサイズの微細凹凸状の境界を形成することにより、凹凸の高さに応じた実質的な屈折率の変調領域が形成される。
上記のとおり、マトリクス10は、好ましくは樹脂成分11および超微粒子成分12を含む。上記のように、ならびに、図1Aおよび図1Bに示すように、超微粒子成分12は、マトリクス10と光拡散性微粒子20との界面近傍に屈折率変調領域30を形成するようにして、樹脂成分11に分散している。
樹脂成分11は、上記微細凹凸状の境界(結果として屈折率変調領域)が形成される限りにおいて、任意の適切な材料で構成される。好ましくは、上記のように、樹脂成分11は、光拡散性微粒子と同系の化合物であってかつ超微粒子成分とは異なる系の化合物で構成される。これにより、マトリクスと光拡散性微粒子との界面近傍(光拡散性微粒子の表面近傍)に屈折率変調領域を良好に形成することができる。さらに好ましくは、樹脂成分11は、光拡散性微粒子と同系の中でも相溶性の高い化合物で構成される。これにより、所望の屈折率勾配を有する屈折率変調領域を形成することができる。
|nP-nA|<|nP-nB|・・・(1)
式(1)中、nAはマトリクスの樹脂成分の屈折率を表し、nBはマトリクスの超微粒子成分の屈折率を表し、nPは光拡散性微粒子の屈折率を表す。さらに、樹脂成分は下記式(2)も満足し得る:
|nP-nA|<|nA-nB|・・・(2)
樹脂成分の屈折率は、好ましくは1.40~1.60である。
超微粒子成分12は、上記のように、好ましくは上記樹脂成分および後述の光拡散性微粒子とは異なる系の化合物で構成され、より好ましくは無機化合物で構成される。好ましい無機化合物としては、例えば、金属酸化物、金属フッ化物が挙げられる。金属酸化物の具体例としては、酸化ジルコニウム(ジルコニア)(屈折率:2.19)、酸化アルミニウム(屈折率:1.56~2.62)、酸化チタン(屈折率:2.49~2.74)、酸化ケイ素(屈折率:1.25~1.46)が挙げられる。金属フッ化物の具体例としては、フッ化マグネシウム(屈折率:1.37)、フッ化カルシウム(屈折率:1.40~1.43)が挙げられる。これらの金属酸化物および金属フッ化物は、光の吸収が少ない上に、電離線硬化型樹脂や熱可塑性樹脂などの有機化合物では発現が難しい屈折率を有しているので、光拡散性微粒子との界面から離れるにつれて超微粒子成分の重量濃度が相対的に高くなることにより、屈折率を大きく変調させることができる。光拡散性微粒子とマトリクスとの屈折率差を大きくすることにより、薄膜であっても高ヘイズを実現でき、かつ、屈折率変調領域が形成されるので後方散乱防止の効果も大きい。特に好ましい無機化合物は、酸化ジルコニウムである。
光拡散性微粒子20もまた、上記微細凹凸状の境界(結果として屈折率変調領域)が良好に形成される限りにおいて、任意の適切な材料で構成される。好ましくは、上記のように、光拡散性微粒子20は、上記マトリクスの樹脂成分と同系の化合物で構成される。例えば、マトリクスの樹脂成分を構成する電離線硬化型樹脂がアクリレート系樹脂である場合には、光拡散性微粒子もまたアクリレート系樹脂で構成されることが好ましい。より具体的には、マトリクスの樹脂成分を構成するアクリレート系樹脂のモノマー成分が例えば上記のようなPETA、NPGDA、DPHA、DPPAおよび/またはTMPTAである場合には、光拡散性微粒子を構成するアクリレート系樹脂は、好ましくは、ポリメチルメタクリレート(PMMA)、ポリメチルアクリレート(PMA)、およびこれらの共重合体、ならびにそれらの架橋物である。PMMAおよびPMAとの共重合成分としては、ポリウレタン、ポリスチレン(PS)、メラミン樹脂が挙げられる。特に好ましくは、光拡散性微粒子は、PMMAで構成される。マトリクスの樹脂成分および超微粒子成分との屈折率や熱力学的特性の関係が適切であるからである。さらに、好ましくは、光拡散性微粒子は、架橋構造(三次元網目構造)を有する。架橋構造の粗密(架橋度)を調整することにより、光拡散性微粒子表面において微粒子を構成するポリマー分子の自由度を制御することができるので、超微粒子成分の分散状態を制御することができ、結果として、所望の形状を有する微細凹凸状の境界により屈折率変調領域を形成することができる。例えば、後述の塗工液を塗布する際の光拡散性微粒子の樹脂成分前駆体(溶媒を含んでいてもよい)に対する膨潤度は、好ましくは100%~200%である。ここで、「膨潤度」とは、架橋度の指標であり、膨潤前の粒子の平均粒径に対する膨潤状態の粒子の平均粒径の比率をいう。
本実施形態の光拡散素子の製造方法は、マトリクスの樹脂成分またはその前駆体と超微粒子成分と光拡散性微粒子とを揮発性溶剤中に溶解または分散させた塗工液を基材に塗布する工程(工程Aとする)と、該基材に塗布された塗工液を乾燥させる工程(工程Bとする)と、を含む。
樹脂成分またはその前駆体、超微粒子成分、および光拡散性微粒子については、それぞれ、上記A-2-1項、A-2-2項およびA-3項で説明したとおりである。代表的には、上記塗工液は前駆体および揮発性溶剤中に超微粒子成分および光拡散性微粒子が分散した分散体である。超微粒子成分および光拡散性微粒子を分散させる手段としては、任意の適切な手段(例えば、超音波処理、攪拌機による分散処理)が採用され得る。
上記塗工液の乾燥方法としては、任意の適切な方法が採用され得る。具体例としては、自然乾燥、加熱乾燥、減圧乾燥が挙げられる。好ましくは、加熱乾燥である。加熱温度は、例えば60℃~150℃であり、加熱時間は、例えば30秒~5分である。
好ましくは、上記製造方法は、上記塗布工程の後に上記前駆体を重合させる工程(工程C)をさらに含む。重合方法は、樹脂成分(したがって、その前駆体)の種類に応じて任意の適切な方法が採用され得る。例えば、樹脂成分が電離線硬化型樹脂である場合には、電離線を照射することにより前駆体を重合する。電離線として紫外線を用いる場合には、その積算光量は、好ましくは50mJ/cm2~1000mJ/cm2である。電離線の光拡散性微粒子に対する透過率は、好ましくは70%以上であり、より好ましくは80%以上である。また例えば、樹脂成分が熱硬化型樹脂である場合には、加熱することにより前駆体を重合する。加熱温度および加熱時間は、樹脂成分の種類に応じて適切に設定され得る。好ましくは、重合は電離線を照射することにより行われる。電離線照射であれば、屈折率変調領域を良好に保持したまま塗膜を硬化させることができるので、良好な拡散特性の光拡散素子を作製することができる。前駆体を重合することにより、光拡散性微粒子との界面近傍において屈折率の異なる2つの領域が微細凹凸状の境界を形成し、それにより屈折率変調領域30が形成されているマトリクス10が形成される。
図6は、本発明の別の実施形態による光拡散素子の概略断面図である。図6の光拡散素子100’は、マトリクス10と、マトリクス10中に分散された光拡散性微粒子20とを有する。光拡散性微粒子20は、その外郭が微細凹凸形状に形成されており、当該外郭部分により微細凹凸形状でかつ球殻状の境界が形成され、当該境界が屈折率変調領域30を構成する。すなわち、本実施形態においては、微細凹凸形状でかつ球殻状の境界(したがって、屈折率変調領域)は、光拡散性微粒子の表面の凹凸により形成されている。光拡散性微粒子の表面の凹凸は、任意の適切な手段により形成され得る。例えば、光拡散性微粒子の表面を適切な溶媒で処理することにより、微細な凹凸形状を形成することができる。表面処理に用いられる溶媒としては、例えば、メチルエチルケトン(MEK)、メチルイソブチルケトン(MIBK)のようなケトン系溶媒、酢酸エチル、酢酸ブチルのようなエステル系溶媒が挙げられる。マトリクス10は、例えば、超微粒子成分を用いる形態の樹脂成分に関して上記A-2-1項に記載したような樹脂で構成され得る。なお、本実施形態においては、マトリクス10は、超微粒子成分を含んでいてもよく、含んでいなくてもよい。また、微細凹凸形状でかつ球殻状の境界は、光拡散性微粒子の表面の凹凸のみにより形成されてもよく、光拡散性微粒子の表面の凹凸と超微粒子成分の分散濃度の勾配との組み合わせにより形成されてもよい。屈折率変調領域30においては、好ましくは、屈折率が実質的に連続的に変化する。なお、本実施形態においては、光拡散性微粒子が上記第1の領域に対応し、マトリクスが上記第2の領域に対応する。
B-1.光拡散素子付偏光板の全体構成
本発明の光拡散素子付偏光板は、代表的には、液晶表示装置の視認側に配置される。図7は、本発明の好ましい実施形態による光拡散素子付偏光板の概略断面図である。この光拡散素子付偏光板200は、光拡散素子100と偏光子110とを有する。光拡散素子100は、上記A-1項~A-5項に記載した本発明の光拡散素子である。光拡散素子100は、光拡散素子付偏光板が液晶表示装置の視認側に配置された場合に最も視認側となるように配置されている。1つの実施形態においては、光拡散素子100の視認側に低反射層または反射防止処理層(アンチリフレクション処理層)が配置されている(図示せず)。図示例においては、光拡散素子付偏光板200は、偏光子の両側に保護層120および130を有する。光拡散素子、偏光子および保護層は、任意の適切な接着剤層または粘着剤層を介して貼り付けられている。保護層120および130の少なくとも1つは、目的、偏光板の構成および液晶表示装置の構成に応じて省略されてもよい。例えば、光拡散素子を形成する際に用いられる基材が保護層として機能し得る場合には、保護層120が省略され得る。本発明の光拡散素子付偏光板は、コリメートバックライトフロント拡散システムを採用した液晶表示装置における視認側偏光板として特に好適に用いられ得る。
上記偏光子110としては、目的に応じて任意の適切な偏光子が採用され得る。例えば、ポリビニルアルコール系フィルム、部分ホルマール化ポリビニルアルコール系フィルム、エチレン・酢酸ビニル共重合体系部分ケン化フィルム等の親水性高分子フィルムに、ヨウ素や二色性染料等の二色性物質を吸着させて一軸延伸したもの、ポリビニルアルコールの脱水処理物やポリ塩化ビニルの脱塩酸処理物等ポリエン系配向フィルム等が挙げられる。これらのなかでも、ポリビニルアルコール系フィルムにヨウ素などの二色性物質を吸着させて一軸延伸した偏光子が、偏光二色比が高く特に好ましい。これら偏光子の厚さは特に制限されないが、一般的に、1~80μm程度である。
上記保護層120および130は、偏光板の保護層として使用できる任意の適切なフィルムで形成される。当該フィルムの主成分となる材料の具体例としては、トリアセチルセルロース(TAC)等のセルロース系樹脂や、ポリエステル系、ポリビニルアルコール系、ポリカーボネート系、ポリアミド系、ポリイミド系、ポリエーテルスルホン系、ポリスルホン系、ポリスチレン系、ポリノルボルネン系、ポリオレフィン系、(メタ)アクリル系、アセテート系等の透明樹脂等が挙げられる。また、(メタ)アクリル系、ウレタン系、(メタ)アクリルウレタン系、エポキシ系、シリコーン系等の熱硬化型樹脂または紫外線硬化型樹脂等も挙げられる。この他にも、例えば、シロキサン系ポリマー等のガラス質系ポリマーも挙げられる。また、特開2001-343529号公報(WO01/37007)に記載のポリマーフィルムも使用できる。このフィルムの材料としては、例えば、側鎖に置換または非置換のイミド基を有する熱可塑性樹脂と、側鎖に置換または非置換のフェニル基ならびにニトリル基を有する熱可塑性樹脂を含有する樹脂組成物が使用でき、例えば、イソブテンとN-メチルマレイミドからなる交互共重合体と、アクリロニトリル・スチレン共重合体とを有する樹脂組成物が挙げられる。当該ポリマーフィルムは、例えば、上記樹脂組成物の押出成形物であり得る。
図8を参照して、本発明の光拡散素子付偏光板の製造方法の一例について簡単に説明する。図8において、符号111および112は、それぞれ、偏光板および光拡散素子/基材の積層体を巻回するロールであり、符号122は搬送ロールである。図示例では、偏光板(保護層130/偏光子110/保護層120)と、光拡散素子100/基材101の積層体とを矢印方向に送り出し、それぞれの長手方向を揃えた状態で貼り合わせる。その際、光拡散素子100と偏光板の保護層120とが隣接するように貼り合わせる。その後、必要に応じて基材101を剥離することにより、図7に示すような光拡散素子付偏光板200が得られ得る。図示しないが、例えば、偏光板(保護層130/偏光子110)と光拡散素子100/基材101の積層体とを、基材101と偏光子110とが隣接するように貼り合わせ、基材が保護層として機能する光拡散素子付偏光板を作製することもできる。このように、本発明によれば、いわゆるロール・トゥ・ロールを採用することができるので、光拡散素子付偏光板を非常に高い製造効率で製造することができる。さらに、このロール・トゥ・ロール工程は、上記A-4項に記載の光拡散素子の製造工程から連続して行うことができるので、このような手順を採用すれば、光拡散素子付偏光板の製造効率をさらに向上させることができる。
図9は、本発明の好ましい実施形態による液晶表示装置の概略断面図である。液晶表示装置500は、液晶セル510と、液晶セルの両側に配置された偏光板520および530と、偏光板530の外側に設けられたバックライトユニット540と、偏光板520の外側(視認側)に設けられた光拡散素子100とを備える。目的に応じて任意の適切な光学補償板(位相差板)が、液晶セル510と偏光板520および/または530との間に配置され得る。液晶セル510は、一対の基板(代表的には、ガラス基板)511および512と、基板511および512間に配された、表示媒体としての液晶を含む液晶層513とを有する。
マイクロゲージ式厚み計(ミツトヨ社製)にて基材と光拡散素子との合計厚みを測定し、当該合計厚みから基材の厚みを差し引き、光拡散素子の厚みを算出した。
(2)微細凹凸状の境界の確認ならびに凹凸平均ピッチおよび凹凸平均高さの算出
透過型電子顕微鏡(TEM)(日立製作所製、商品名「H-7650」、加速電圧100kV)を用いて、2次元および3次元の画像を観察した。2次元画像については、実施例および比較例で得られた光拡散素子と基材との積層体を液体窒素で冷却しながら、ミクロトームにて0.1μmの厚さにスライスして測定試料とし、当該測定試料の光拡散素子部分の微粒子の状態および当該微粒子とマトリクスとの界面の状態を観察した。3次元画像については、上記で得られた測定試料に撮影位置補正用のマーカーとして直径5nmの金粒子を付着させ、-60°から60°にわたって1°ごとに連続傾斜TEM画像(121枚)を撮影した。この121枚のTEM画像について、Fiducial Marker法により位置補正を行い、3次元画像を再構成した。再構成ソフトとしてIMOD 3.9.3 1を、表示ソフトとしてMercuury Computer Systems,Amiraを用いた。上記のようにして得られた3次元再構成像から、光拡散性微粒子とマトリクスとの界面(実界面)を抽出し、当該実界面に対して近似曲面によるフィッティングを行い、実界面において近似曲面から30nm以上突出している凸部間の距離および凸部の平均高さから微細凹凸状の境界の凹凸の平均ピッチおよび凹凸平均高さを求めた。なお、フィッティングの近似曲線には下記の式を用いた。
z=ax2+by2+cxy+dx+ey+f
(3)ヘイズ
JIS 7136で定める方法により、ヘイズメーター(村上色彩科学研究所社製、商品名「HN-150」)を用いて測定した。
(4)光拡散半値角
光拡散素子の正面からレーザー光を照射し、拡散した光の拡散角度に対する拡散輝度を、ゴニオフォトメーターで1°おきに測定し、図12に示すように、レーザーの直進透過光を除く光拡散輝度の最大値から半分の輝度となる拡散角度を、拡散の両側で測定し、当該両側の角度を足したもの(図12の角度A+角度A’)を光拡散半値角とした。
(5)後方散乱率
実施例および比較例で得られた光拡散素子と基材との積層体を、透明粘着剤を介して黒アクリル板(住友化学社製、商品名「SUMIPEX」(登録商標)、厚み2mm)の上に貼り合わせ、測定試料とした。この測定試料の積分反射率を分光光度計(日立計測器社製、商品名「U4100」)にて測定した。一方、上記光拡散素子用塗工液から微粒子を除去した塗工液を用いて、基材と透明塗工層との積層体を作製して対照試料とし、上記と同様にして積分反射率(すなわち、表面反射率)を測定した。上記測定試料の積分反射率から上記対照試料の積分反射率(表面反射率)を差し引くことにより、光拡散素子の後方散乱率を算出した。
超微粒子成分としてのジルコニアナノ粒子(平均1次粒子径10nm、平均粒子径60nm、屈折率2.19)を62%含有するハードコート用樹脂(JSR社製、商品名「オプスターKZ6661」(MEK/MIBK含有))100部に、樹脂成分の前駆体としてのペンタエリスリトールトリアクリレート(大阪有機化学工業社製、商品名「ビスコート#300」、屈折率1.52)の50%メチルエチルケトン(MEK)溶液を11部、光重合開始剤(BASFジャパン社製、商品名「イルガキュア907」)を0.5部、レベリング剤(DIC社製、商品名「GRANDIC PC 4100」)を0.5部、および、光拡散性微粒子としてのポリメタクリル酸メチル(PMMA)微粒子(積水化成品工業社製、商品名「SAX-102」、平均粒径2.5μm、屈折率1.495)を15部添加した。攪拌機(浅田鉄工株式会社製、商品名「デスパ(DESPA)」)を用いてこの混合物を30分間攪拌して分散処理を行い、上記の各成分が均一に分散した塗工液を調製した。この塗工液の固形分濃度は55%であった。当該塗工液を調製後ただちに、バーコーターを用いてTACフィルム(富士フィルム社製、商品名「フジタック」、厚み40μm)からなる基材上に塗工し、100℃にて1分間乾燥後、積算光量300mJ/cm2の紫外線を照射し、厚み11μmの光拡散素子を得た。得られた光拡散素子におけるマトリクスの平均屈折率nMと光拡散性微粒子の屈折率nPとの差は0.12(nM>nP)であった。得られた光拡散素子を上記(1)~(5)の評価に供した。結果を、後述の実施例2~10および比較例1~3の結果と併せて表1に示す。さらに、得られた光拡散素子をTEMで観察した。結果を図13に示す。当該TEM画像から3次元画像を再構成し、さらに当該3次元再構成像を2値化した。その結果、図2B~図2Eに示すような微細凹凸状の境界が形成されていることを確認した。加えて、当該TEM画像から、光拡散性微粒子表面からの距離と超微粒子成分の分散濃度(存在比率)との関係を算出した。その結果、図3に示すように、超微粒子成分の分散濃度の勾配が形成されていることを確認した。
光拡散性微粒子としてポリメタクリル酸メチル(PMMA)微粒子(積水化成品工業社製、商品名「XX-131AA」、平均粒径2.5μm、屈折率1.495)を用いたこと以外は実施例1と同様にして、厚み10μmの光拡散素子を得た。得られた光拡散素子を実施例1と同様の評価に供した。結果を上記表1に示す。形成された微細凹凸状の境界において、凸部間の最大距離は32nm、であり、平均ピッチは19nmであった。また、凹凸の最大高さは78nmであり、凹凸平均高さは52nmであった。
光拡散性微粒子としてのポリメタクリル酸メチル(PMMA)微粒子(根上工業社製、商品名「アートパールJ4P」、平均粒径2.5μm、屈折率1.495)を用いたこと以外は実施例1と同様にして、厚み10μmの光拡散素子を得た。得られた光拡散素子を実施例1と同様の評価に供した。結果を上記表1に示す。
超微粒子成分としてチタニアナノ粒子(平均1次粒子径10nm、平均粒子径60nm、屈折率2.3)を60%含有するハードコート用樹脂(JSR社製、MEK/PGME含有)100部を用いたこと以外は実施例3と同様にして、厚み11μmの光拡散素子を得た。得られた光拡散素子を実施例1と同様の評価に供した。結果を上記表1に示す。
樹脂成分の前駆体としてヒドロキシエチルアクリルアミド(株式会社興人製、商品名「HEAA」、屈折率1.52)の50%MEK溶液11部を用いたこと以外は実施例3と同様にして、厚み11μmの光拡散素子を得た。得られた光拡散素子を実施例1と同様の評価に供した。結果を上記表1に示す。
樹脂成分の前駆体としてアクリロイルモルホリン(株式会社興人製、商品名「ACMO」、屈折率1.52)の50%MEK溶液11部を用いたこと以外は実施例3と同様にして、厚み10μmの光拡散素子を得た。得られた光拡散素子を実施例1と同様の評価に供した。結果を上記表1に示す。
光拡散性微粒子としてポリメタクリル酸メチル(PMMA)に親水基を付与した微粒子(積水化成品工業製、商品名「XX-157-AA」、平均粒子径2.5μm、屈折率1.495)15部を用いたこと以外は実施例1と同様にして、厚み10μmの光拡散素子を得た。得られた光拡散素子を実施例1と同様の評価に供した。結果を上記表1に示す。
光拡散性微粒子としてポリメタクリル酸メチル(PMMA)とポリスチレン(PS)の共重合微粒子(積水化成品工業製、商品名「XX-164-AA」、平均粒子径2.5μm、屈折率1.495)15部を用いたこと以外は実施例1と同様にして、厚み10μmの光拡散素子を得た。得られた光拡散素子を実施例1と同様の評価に供した。結果を上記表1に示す。
超微粒子成分としてのジルコニアナノ粒子のハードコート用樹脂中の含有量を25%としたこと以外は実施例1と同様にして、厚み9μmの光拡散素子を得た。得られた光拡散素子を実施例1と同様の評価に供した。結果を上記表1に示す。
超微粒子成分としてシリカナノ粒子(平均1次粒子径10nm、平均粒子径40nm、屈折率1.49)を30%含有するハードコート用樹脂(JSR社製、商品名「Z7540」)100部に、光拡散性微粒子としてポリスチレン(PS)微粒子(綜研化学社製、商品名「SX-350H」、平均粒子径3.5μm、屈折率1.595)15部を添加したこと、ならびに、当該PS微粒子の表面をMEKで処理して微細凹凸形状としたこと(PS微粒子を金平糖のような形状としたこと)以外は実施例1と同様にして、厚み10μmの光拡散素子を得た。得られた光拡散素子を実施例1と同様の評価に供した。結果を上記表1に示す。さらに、得られた光拡散素子の光拡散性微粒子近傍のTEM画像を図14に示す。このTEM画像から、微細凹凸状の境界が形成されていることを確認した。
光拡散性微粒子としてPMMA微粒子の代わりにシリコーン樹脂微粒子(モメンティブ・パフォーマンス・マテリアルズ社製、商品名「トスパール120」、平均粒径2.0μm、屈折率1.43)を用いたこと以外は実施例1と同様にして、厚み13μmの光拡散素子を得た。得られた光拡散素子を実施例1と同様の評価に供した。結果を上記表1に示す。
超微粒子成分としてのジルコニアナノ粒子を含まないハードコート用樹脂を用いたこと以外は実施例1と同様にして、厚み10μmの光拡散素子を得た。得られた光拡散素子を実施例1と同様の評価に供した。結果を上記表1に示す。さらに、得られた光拡散素子の光拡散性微粒子近傍のTEM画像を図15に示す。このTEM画像から、光拡散性微粒子とマトリクスとの界面は明確であり、微細凹凸状の境界は形成されていないことがわかる。
光拡散性微粒子としてシリカにメチル修飾を施した微粒子(日本触媒製、商品名「シーホスターKE-250」)15部を用いたこと以外は実施例1と同様にして、厚み10μmの光拡散素子を得た。得られた光拡散素子を実施例1と同様の評価に供した。結果を上記表1に示す。
マルチドメイン型VAモードの液晶セルを備える市販の液晶テレビ(SONY社製、ブラビア20型、商品名「KDL20J3000」)から液晶セルを取り出した。当該液晶セルの両側に、市販の偏光板(日東電工社製、商品名「NPF-SEG1423DU」)を、それぞれの偏光子の吸収軸が直交するようにして貼り合わせた。より具体的には、バックライト側偏光板の偏光子の吸収軸方向が垂直方向(液晶パネルの長辺方向に対して90°)となり、視認側偏光板の偏光子の吸収軸方向が水平方向(液晶パネルの長辺方向に対して0°)となるようにして貼り合わせた。さらに、視認側偏光板の外側に、実施例1の光拡散素子を基材から転写して貼り合わせ、液晶パネルを作製した。
比較例1の光拡散素子を用いたこと以外は実施例11と同様にして液晶表示装置を作製した。得られた液晶表示装置について暗所にて白表示および黒表示を行い、その表示状態を目視にて観察した。その結果、斜め方向から見た場合、暗所の白表示の輝度は高かったが、明所での黒表示は白ぼけて見えた。
比較例2の光拡散素子を用いたこと以外は実施例11と同様にして液晶表示装置を作製した。得られた液晶表示装置について暗所にて白表示および黒表示を行い、その表示状態を目視にて観察した。その結果、斜め方向から見た場合、暗所の白表示の輝度は高かったが、明所での黒表示は白ぼけて見えた。
実施例1の光拡散素子の代わりに実施例2の光拡散素子を用いたこと以外は実施例11と同様にして液晶表示装置を作製した。得られた液晶表示装置について暗所にて白表示および黒表示を行い、その表示状態を目視にて観察した。その結果、斜め方向から見た場合、明所での黒表示が黒くかつ暗所の白表示の輝度が高いという良好な表示特性を示した。
実施例1の光拡散素子の代わりに実施例3の光拡散素子を用いたこと以外は実施例11と同様にして液晶表示装置を作製した。得られた液晶表示装置について暗所にて白表示および黒表示を行い、その表示状態を目視にて観察した。その結果、斜め方向から見た場合、明所での黒表示が黒くかつ暗所の白表示の輝度が高いという良好な表示特性を示した。
表1から明らかなように、微細凹凸状の境界が形成された実施例の光拡散素子は、ヘイズが高く、かつ、後方散乱率が低かった。また、実施例の光拡散素子は、厚みが9μm~11μmであり、非常に薄い。さらに、実施例の光拡散素子は、コリメートバックライトフロント拡散システムの液晶表示装置のフロント拡散素子として用いた場合に、非常に優れた表示特性を示した。一方、微細凹凸状の境界が形成されない比較例1の光拡散素子は、ヘイズは高いが後方散乱率が高く、比較例2の光拡散素子は、後方散乱率は低いがヘイズはきわめて不十分であった。比較例の光拡散素子は、コリメートバックライトフロント拡散システムの液晶表示装置のフロント拡散素子として用いた場合に、明所での黒表示が白ぼけるという問題が認められた。
11 樹脂成分
12 超微粒子成分
20 光拡散性微粒子
25 微細凹凸状の境界
30 屈折率変調領域
100、100’ 光拡散素子
110 偏光子
120 保護層
130 保護層
200 光拡散素子付偏光板
500 液晶表示装置
Claims (10)
- 第1の屈折率を有する第1の領域と第2の屈折率を有する第2の領域とを有し、
該第1の領域および該第2の領域が微細凹凸状でかつ球殻状の境界を形成している、
光拡散素子。 - マトリクスと該マトリクス中に分散された光拡散性微粒子とを有し、
該マトリクスと該光拡散性微粒子との界面またはその近傍にて屈折率の異なる2つの領域が微細凹凸状でかつ球殻状の境界を形成している、
光拡散素子。 - 前記マトリクスが樹脂成分および超微粒子成分を含み、前記微細凹凸状でかつ球殻状の境界が、該マトリクス中の該超微粒子成分が分散している領域と分散していない領域とにより形成されている、請求項2に記載の光拡散素子。
- 前記微細凹凸状でかつ球殻状の境界が、前記光拡散性微粒子の表面の凹凸により形成されている、請求項2または3に記載の光拡散素子。
- 前記超微粒子成分の平均1次粒子径が1nm~100nmである、請求項2から4のいずれかに記載の光拡散素子。
- ヘイズが90%~99.9%である、請求項2から5のいずれかに記載の光拡散素子。
- 厚みが4μm~50μmである、請求項2から6のいずれかに記載の光拡散素子。
- 光拡散半値角が10°~150°である、請求項2から7のいずれかに記載の光拡散素子。
- 請求項1から8のいずれかに記載の光拡散素子と偏光子とを有する、光拡散素子付偏光板。
- 液晶セルと、
該液晶セルに向かってコリメート光を出射する平行光光源装置と、
該液晶セルを通過したコリメート光を透過および拡散させる、請求項1から8のいずれかに記載の光拡散素子と、を備える
液晶表示装置。
Priority Applications (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP11825269.1A EP2618184A4 (en) | 2010-09-17 | 2011-09-16 | LIGHT-SPREADING ELEMENT, POLARIZER WITH LIGHT-SPREADING ELEMENT AND LIQUID CRYSTAL DISPLAY DEVICE THEREWITH |
CN201180044550.8A CN103109212B (zh) | 2010-09-17 | 2011-09-16 | 光扩散元件、带光扩散元件的偏振板、及使用其的液晶显示装置 |
KR1020137006558A KR20130041335A (ko) | 2010-09-17 | 2011-09-16 | 광 확산 소자, 광 확산 소자가 형성된 편광판 및 이들을 사용한 액정 표시 장치 |
KR1020167005349A KR20160031033A (ko) | 2010-09-17 | 2011-09-16 | 광 확산 소자, 광 확산 소자가 형성된 편광판 및 이들을 사용한 액정 표시 장치 |
US13/822,581 US9804304B2 (en) | 2010-09-17 | 2011-09-16 | Light-diffusing element, polarizer having light-diffusing element, and liquid crystal display device having same |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2010210128 | 2010-09-17 | ||
JP2010-210128 | 2010-09-17 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2012036271A1 true WO2012036271A1 (ja) | 2012-03-22 |
Family
ID=45831724
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP2011/071230 WO2012036271A1 (ja) | 2010-09-17 | 2011-09-16 | 光拡散素子、光拡散素子付偏光板、およびこれらを用いた液晶表示装置 |
Country Status (7)
Country | Link |
---|---|
US (1) | US9804304B2 (ja) |
EP (1) | EP2618184A4 (ja) |
JP (2) | JP6275935B2 (ja) |
KR (2) | KR20130041335A (ja) |
CN (1) | CN103109212B (ja) |
TW (1) | TWI468741B (ja) |
WO (1) | WO2012036271A1 (ja) |
Families Citing this family (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR20140142562A (ko) * | 2013-06-04 | 2014-12-12 | 삼성디스플레이 주식회사 | 표시장치용 윈도우 및 이를 포함하는 표시 장치 |
JP2015014692A (ja) * | 2013-07-04 | 2015-01-22 | シャープ株式会社 | 光拡散部材及び表示装置 |
TWI502242B (zh) * | 2014-05-28 | 2015-10-01 | Au Optronics Corp | 透鏡結構 |
JP6483845B2 (ja) * | 2015-09-30 | 2019-03-13 | 積水化成品工業株式会社 | 光拡散性樹脂組成物の成形体及びその用途 |
CN106168689B (zh) * | 2016-07-11 | 2019-05-14 | 浙江元泰特种膜有限公司 | 一种高雾高亮光学膜制造方法 |
CN106249326B (zh) * | 2016-07-11 | 2019-05-21 | 浙江元泰特种膜有限公司 | 一种上扩散光学膜制造方法 |
JPWO2018123543A1 (ja) * | 2016-12-28 | 2019-10-31 | 日華化学株式会社 | 光拡散膜、光拡散膜形成用コーティング剤及びその製造方法、並びに、投影スクリーン及びその製造方法 |
JP2019053168A (ja) * | 2017-09-14 | 2019-04-04 | 日東電工株式会社 | 光学積層体 |
TWI640972B (zh) * | 2017-12-14 | 2018-11-11 | 宏齊科技股份有限公司 | 顯示裝置及其光源模組 |
US20210157223A1 (en) | 2018-04-17 | 2021-05-27 | Nitto Denko Corporation | Projection screen optical laminate and projection screen using optical laminate |
WO2020231195A1 (en) | 2019-05-15 | 2020-11-19 | Samsung Electronics Co., Ltd. | Light-diffuser, light diffusing adhesive, light diffusing hard coat member, light diffusion film, and image forming apparatus including light diffusion film |
WO2022196599A1 (ja) * | 2021-03-19 | 2022-09-22 | 富士フイルム株式会社 | 膜および光センサ |
Citations (20)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH01126627A (ja) | 1987-11-11 | 1989-05-18 | Hitachi Ltd | 液晶表示装置 |
JPH0371538B2 (ja) | 1985-03-07 | 1991-11-13 | Yanmar Diesel Engine Co | |
JPH06130255A (ja) | 1992-10-15 | 1994-05-13 | Ricoh Co Ltd | Led用光カプラー及び情報読取り装置 |
JPH06347617A (ja) | 1993-06-10 | 1994-12-22 | Nitto Denko Corp | 光拡散板及びその製造方法並びに表示装置 |
WO2001037007A1 (fr) | 1999-11-12 | 2001-05-25 | Kaneka Corporation | Film transparent |
JP2001343529A (ja) | 2000-03-30 | 2001-12-14 | Kanegafuchi Chem Ind Co Ltd | 偏光子保護フィルムおよびその製造方法 |
JP2002214408A (ja) | 2001-01-12 | 2002-07-31 | Fuji Photo Film Co Ltd | 光拡散体及び表示装置 |
JP2002212245A (ja) | 2001-01-12 | 2002-07-31 | Fuji Photo Film Co Ltd | 光拡散性粒子の製造方法 |
JP2002328207A (ja) | 2001-05-01 | 2002-11-15 | Fuji Photo Film Co Ltd | 光拡散体およびこれを備えた表示装置 |
JP3442247B2 (ja) | 1996-02-01 | 2003-09-02 | 三菱レイヨン株式会社 | 面光源素子用導光体および面光源素子 |
JP2003262710A (ja) | 2003-01-20 | 2003-09-19 | Yasuhiro Koike | 光拡散体 |
JP2004038009A (ja) * | 2002-07-05 | 2004-02-05 | Fuji Photo Film Co Ltd | 液晶表示装置 |
JP2006227279A (ja) | 2005-02-17 | 2006-08-31 | Dainippon Printing Co Ltd | 光拡散シート及び透過型スクリーン |
JP2007279424A (ja) | 2006-04-07 | 2007-10-25 | Three M Innovative Properties Co | 覗き見防止シート及びそれを含むディスプレイ装置 |
JP2008180961A (ja) | 2007-01-25 | 2008-08-07 | Nitto Denko Corp | 積層光学フィルム、積層光学フィルムを用いた液晶パネルおよび液晶表示装置 |
JP2008262012A (ja) | 2007-04-12 | 2008-10-30 | Citizen Electronics Co Ltd | 光学部材及びバックライトユニット並び表示装置 |
JP2009070814A (ja) * | 2007-08-21 | 2009-04-02 | Fujifilm Corp | 散乱部材を有する有機エレクトロルミネッセンス表示装置 |
JP2009244383A (ja) * | 2008-03-28 | 2009-10-22 | Fujifilm Corp | 液晶表示装置 |
JP2010077243A (ja) | 2008-09-25 | 2010-04-08 | Jsr Corp | 光拡散粒子、その製造方法、光拡散粒子組成物、及び光拡散フィルム |
JP2010107616A (ja) | 2008-10-02 | 2010-05-13 | Jsr Corp | 光拡散性粒子およびその製造方法、光拡散性樹脂組成物並びにその応用 |
Family Cites Families (21)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2657536B2 (ja) * | 1988-10-29 | 1997-09-24 | 大日本印刷株式会社 | 光拡散シート |
JP3178009B2 (ja) | 1991-07-05 | 2001-06-18 | 株式会社日立製作所 | 反射防止体及びその利用装置 |
JP3071538B2 (ja) | 1992-01-17 | 2000-07-31 | 日東電工株式会社 | 光線平行化装置及び液晶表示装置 |
JP3408581B2 (ja) * | 1993-06-10 | 2003-05-19 | 康博 小池 | 光拡散体 |
US6502943B2 (en) | 2000-07-19 | 2003-01-07 | Fuji Photo Film Co., Ltd. | Antiglare and antireflection film, polarizer, and image display device |
EP1442322B1 (en) * | 2001-10-11 | 2008-07-30 | FUJIFILM Corporation | Diffusion film comprising transparent substrate and diffusion layer |
JP2003307728A (ja) | 2002-04-18 | 2003-10-31 | Nitto Denko Corp | 反射型液晶表示装置 |
JP2005004163A (ja) * | 2002-09-30 | 2005-01-06 | Fuji Photo Film Co Ltd | 光学機能性フィルム、偏光板及び画像表示装置 |
US20060227695A1 (en) | 2003-09-17 | 2006-10-12 | Fuji Photo Film Co., Ltd. | Recording media |
US20070121227A1 (en) * | 2004-07-02 | 2007-05-31 | Efun Technology Co., Ltd. | Brightness enhancement film having curved prism units and light scattering particles |
US20070298193A1 (en) | 2004-09-16 | 2007-12-27 | Kazuhiro Nakamura | Method of Producing Light-Scattering Film, Polarizing Plate Comprising Light-Scattering Film and Liquid Crystal Display Device Comprising the Polarizing Plate |
US20070030415A1 (en) | 2005-05-16 | 2007-02-08 | Epstein Kenneth A | Back-lit displays with high illumination uniformity |
TW200730886A (en) * | 2005-12-21 | 2007-08-16 | Nippon Catalytic Chem Ind | Light diffusing sheet and light diffusing plate, and backlight unit and liquid crystal display device employing the same |
US20090051278A1 (en) | 2007-08-21 | 2009-02-26 | Fujifilm Corporation | Organic electroluminescent display device having scattering member |
KR20090019752A (ko) | 2007-08-21 | 2009-02-25 | 후지필름 가부시키가이샤 | 산란 부재 및 그것을 사용하는 유기 일렉트로루미네선스 표시 장치 |
KR20090039475A (ko) * | 2007-10-18 | 2009-04-22 | 한화석유화학 주식회사 | 요철형 단분산 광확산제의 제조방법 |
CN101602254A (zh) * | 2008-06-12 | 2009-12-16 | 颖台科技股份有限公司 | 非对称光扩散元件与其制造方法 |
KR20100020906A (ko) | 2008-08-13 | 2010-02-23 | 소니 가부시끼가이샤 | 광학 필름 및 그 제조 방법, 눈부심방지성 필름, 광학층이 부착된 편광자 및 표시 장치 |
JP4756099B2 (ja) | 2009-03-18 | 2011-08-24 | 日東電工株式会社 | 光拡散素子、光拡散素子付偏光板、およびこれらを用いた液晶表示装置、ならびに光拡散素子の製造方法 |
TW201037405A (en) | 2009-04-14 | 2010-10-16 | Dayu Optoelectronics Co Ltd | Composite brightness enhancement film having two-phase hazing layer |
JP5883598B2 (ja) | 2010-09-17 | 2016-03-15 | 日東電工株式会社 | 光拡散素子および光拡散素子付偏光板の製造方法、ならびに、これらの方法で得られた光拡散素子および光拡散素子付偏光板 |
-
2011
- 2011-09-15 JP JP2011202285A patent/JP6275935B2/ja not_active Expired - Fee Related
- 2011-09-16 US US13/822,581 patent/US9804304B2/en active Active
- 2011-09-16 EP EP11825269.1A patent/EP2618184A4/en not_active Withdrawn
- 2011-09-16 TW TW100133553A patent/TWI468741B/zh not_active IP Right Cessation
- 2011-09-16 KR KR1020137006558A patent/KR20130041335A/ko active Application Filing
- 2011-09-16 KR KR1020167005349A patent/KR20160031033A/ko not_active Application Discontinuation
- 2011-09-16 CN CN201180044550.8A patent/CN103109212B/zh active Active
- 2011-09-16 WO PCT/JP2011/071230 patent/WO2012036271A1/ja active Application Filing
-
2017
- 2017-08-07 JP JP2017152404A patent/JP2017201432A/ja not_active Withdrawn
Patent Citations (20)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH0371538B2 (ja) | 1985-03-07 | 1991-11-13 | Yanmar Diesel Engine Co | |
JPH01126627A (ja) | 1987-11-11 | 1989-05-18 | Hitachi Ltd | 液晶表示装置 |
JPH06130255A (ja) | 1992-10-15 | 1994-05-13 | Ricoh Co Ltd | Led用光カプラー及び情報読取り装置 |
JPH06347617A (ja) | 1993-06-10 | 1994-12-22 | Nitto Denko Corp | 光拡散板及びその製造方法並びに表示装置 |
JP3442247B2 (ja) | 1996-02-01 | 2003-09-02 | 三菱レイヨン株式会社 | 面光源素子用導光体および面光源素子 |
WO2001037007A1 (fr) | 1999-11-12 | 2001-05-25 | Kaneka Corporation | Film transparent |
JP2001343529A (ja) | 2000-03-30 | 2001-12-14 | Kanegafuchi Chem Ind Co Ltd | 偏光子保護フィルムおよびその製造方法 |
JP2002214408A (ja) | 2001-01-12 | 2002-07-31 | Fuji Photo Film Co Ltd | 光拡散体及び表示装置 |
JP2002212245A (ja) | 2001-01-12 | 2002-07-31 | Fuji Photo Film Co Ltd | 光拡散性粒子の製造方法 |
JP2002328207A (ja) | 2001-05-01 | 2002-11-15 | Fuji Photo Film Co Ltd | 光拡散体およびこれを備えた表示装置 |
JP2004038009A (ja) * | 2002-07-05 | 2004-02-05 | Fuji Photo Film Co Ltd | 液晶表示装置 |
JP2003262710A (ja) | 2003-01-20 | 2003-09-19 | Yasuhiro Koike | 光拡散体 |
JP2006227279A (ja) | 2005-02-17 | 2006-08-31 | Dainippon Printing Co Ltd | 光拡散シート及び透過型スクリーン |
JP2007279424A (ja) | 2006-04-07 | 2007-10-25 | Three M Innovative Properties Co | 覗き見防止シート及びそれを含むディスプレイ装置 |
JP2008180961A (ja) | 2007-01-25 | 2008-08-07 | Nitto Denko Corp | 積層光学フィルム、積層光学フィルムを用いた液晶パネルおよび液晶表示装置 |
JP2008262012A (ja) | 2007-04-12 | 2008-10-30 | Citizen Electronics Co Ltd | 光学部材及びバックライトユニット並び表示装置 |
JP2009070814A (ja) * | 2007-08-21 | 2009-04-02 | Fujifilm Corp | 散乱部材を有する有機エレクトロルミネッセンス表示装置 |
JP2009244383A (ja) * | 2008-03-28 | 2009-10-22 | Fujifilm Corp | 液晶表示装置 |
JP2010077243A (ja) | 2008-09-25 | 2010-04-08 | Jsr Corp | 光拡散粒子、その製造方法、光拡散粒子組成物、及び光拡散フィルム |
JP2010107616A (ja) | 2008-10-02 | 2010-05-13 | Jsr Corp | 光拡散性粒子およびその製造方法、光拡散性樹脂組成物並びにその応用 |
Non-Patent Citations (1)
Title |
---|
See also references of EP2618184A4 |
Also Published As
Publication number | Publication date |
---|---|
TWI468741B (zh) | 2015-01-11 |
EP2618184A4 (en) | 2015-12-09 |
JP2012083741A (ja) | 2012-04-26 |
JP2017201432A (ja) | 2017-11-09 |
JP6275935B2 (ja) | 2018-02-07 |
KR20130041335A (ko) | 2013-04-24 |
EP2618184A1 (en) | 2013-07-24 |
CN103109212A (zh) | 2013-05-15 |
US9804304B2 (en) | 2017-10-31 |
CN103109212B (zh) | 2016-02-03 |
US20130300980A1 (en) | 2013-11-14 |
KR20160031033A (ko) | 2016-03-21 |
TW201219849A (en) | 2012-05-16 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
JP6275935B2 (ja) | 光拡散素子、光拡散素子付偏光板、およびこれらを用いた液晶表示装置 | |
JP4756099B2 (ja) | 光拡散素子、光拡散素子付偏光板、およびこれらを用いた液晶表示装置、ならびに光拡散素子の製造方法 | |
US9176264B2 (en) | Light-diffusing element, polarizing plate having light-diffusing element attached thereto, polarizing element, and liquid crystal display device equipped with those components | |
JP6275936B2 (ja) | 光拡散フィルム、光拡散フィルム付偏光板、液晶表示装置および照明器具 | |
KR101927681B1 (ko) | 광확산 소자 및 광확산 소자를 가진 편광판 | |
JP4756100B2 (ja) | 光拡散素子の製造方法、光拡散素子、ならびに、光拡散素子付偏光板および液晶表示装置の製造方法 | |
JP5883598B2 (ja) | 光拡散素子および光拡散素子付偏光板の製造方法、ならびに、これらの方法で得られた光拡散素子および光拡散素子付偏光板 | |
JP5129379B2 (ja) | 光拡散素子 | |
WO2014167665A1 (ja) | 光拡散素子および光拡散素子の製造方法 | |
JP2013195813A (ja) | 光拡散素子および光拡散素子の製造方法 |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
WWE | Wipo information: entry into national phase |
Ref document number: 201180044550.8 Country of ref document: CN |
|
121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 11825269 Country of ref document: EP Kind code of ref document: A1 |
|
ENP | Entry into the national phase |
Ref document number: 20137006558 Country of ref document: KR Kind code of ref document: A |
|
REEP | Request for entry into the european phase |
Ref document number: 2011825269 Country of ref document: EP |
|
WWE | Wipo information: entry into national phase |
Ref document number: 2011825269 Country of ref document: EP |
|
NENP | Non-entry into the national phase |
Ref country code: DE |
|
WWE | Wipo information: entry into national phase |
Ref document number: 13822581 Country of ref document: US |