JP5194486B2 - Liquid crystal display - Google Patents

Description

  The present invention relates to a liquid crystal display device with improved antiglare properties and a set of polarizing plates useful for the liquid crystal display device.

  Liquid crystal display devices are increasingly used for portable TVs, notebook personal computers, etc. due to their characteristics such as light weight, thinness, and low power consumption. Today, they are also being applied to video viewing equipment such as large TVs. Yes. In a liquid crystal display device used for the purpose of displaying an image such as a television receiver, the visibility, particularly the contrast ratio when observed from the front and the contrast ratio when observed from an oblique direction, that is, viewing angle characteristics, is regarded as important. The In order to improve such viewing angle characteristics, various liquid crystal cell drive modes have been proposed.

  As a driving mode of the liquid crystal cell capable of essentially expanding the viewing angle, for example, an optically compensated bend (OCB) mode, a vertical alignment (VA) mode, a lateral electric field (In-Plane Switching): IPS) mode. Among these, the IPS mode is a conventional twisted nematic (TN) mode liquid crystal cell that changes the alignment state of liquid crystal molecules by a vertical electric field in which a voltage is applied in a direction perpendicular to the substrate surface. The orientation state of the liquid crystal molecules is changed by a lateral electric field in which a voltage is applied in a direction parallel to the liquid crystal. In the IPS mode, the liquid crystal molecules are aligned in parallel to the substrate surface when no voltage is applied, but are not twisted as in the TN mode but are aligned in substantially the same direction.

  In such an IPS mode liquid crystal display device, in the configuration in which only the linearly polarizing plate is disposed with the liquid crystal cell interposed therebetween, the axial angle of the disposed linearly polarizing plate is 90 ° when viewed obliquely. Due to the shift and the rod-like liquid crystal molecules in the cell exhibit birefringence, light leakage occurs and the contrast ratio is significantly reduced.

  In an IPS mode liquid crystal display device, in order to eliminate such light leakage, it is necessary to dispose an optical compensation film between the liquid crystal cell and the linear polarizing plate. In order to compensate for the birefringence change of the liquid crystal layer due to the change in viewing angle in the IPS mode liquid crystal display device, a retardation plate having an optically negative uniaxial property and its optical axis parallel to the film surface, It is known that a retardation plate oriented in the above is effective. For example, in Japanese Patent Laid-Open No. 10-54982 (Patent Document 1), in an IPS mode liquid crystal display device, the optical axis is optically negative uniaxial between a liquid crystal cell and at least one polarizing plate. It describes that an optical compensation sheet (retardation plate) in a direction parallel to the film surface is arranged. JP-A-11-133408 (Patent Document 2) discloses a positive uniaxial property perpendicular to the substrate surface between a pair of polarizing plates in an IPS mode liquid crystal display device, that is, between a liquid crystal cell and a polarizing plate. It is described that a compensation layer (retardation plate) having an optical axis is arranged in any direction. Further, in Japanese Patent Application Laid-Open No. 2005-309110 (Patent Document 3) relating to the application of the present applicant, in an IPS mode liquid crystal display device, an in-plane retardation value is respectively provided between a liquid crystal cell and a pair of upper and lower polarizing plates. It is disclosed that different retardation plates are arranged.

  As a method for orienting a resin film in the thickness direction, for example, in Japanese Patent Laid-Open No. 7-230007 (Patent Document 4), a film having heat shrinkability is provided on at least one surface of a uniaxially stretched thermoplastic resin film. A method is disclosed in which the heat-shrinkable film is bonded and peeled so that the heat-shrink direction of the shrinkable film is orthogonal to the stretched-axis direction of the uniaxially stretched thermoplastic resin film, and then the heat-shrinkable film is peeled and removed. .

  On the other hand, image display devices such as liquid crystal display devices, when external light is reflected on the image display surface, the visibility is significantly impaired, so in applications such as televisions and personal computers where importance is placed on image quality and visibility, A process for preventing these reflections is usually performed on the surface of the display device. As anti-reflection processing, so-called anti-glare processing that scatters incident light and blurs the reflected image by forming fine irregularities on the surface can be realized at a relatively low cost. It is suitably used for such applications.

  As a film having such an antiglare property, for example, in JP 2002-189106 A (Patent Document 5), the ionizing radiation curable resin is sandwiched between an embossing mold and a transparent resin film. By curing the ionizing radiation curable resin, the three-dimensional 10-point average roughness and the average distance between adjacent convex portions on the three-dimensional roughness reference surface are each formed with fine irregularities having a predetermined value, An antiglare film having a shape in which an ionizing radiation curable resin layer having such irregularities is provided on the transparent resin film is disclosed.

  Furthermore, as a method for producing a roll used for manufacturing a film having irregularities on the surface, for example, in Japanese Patent Application Laid-Open No. 2004-90187 (Patent Document 6), a step of forming a metal plating layer on the surface of an embossing roll, metal plating Disclosed is a method for producing an embossing roll through a step of mirror polishing the surface of a layer, a step of blasting the surface of a mirror-plated metal plating layer using ceramic beads, and a step of peening treatment if necessary. Yes.

  Now, in general, it is said that it is necessary to use an anti-glare film exhibiting a high haze value of 10% or more in order to prevent reflection of external light and ensure sufficient visibility. High-value anti-glare films have been widely used in notebook personal computers and televisions. However, the antiglare film showing a high haze value of 10% or more has a problem that the contrast measured in a bright room is lowered due to its wide reflection / scattering characteristics. Another problem is that the contrast measured in a dark room, which is inherent in a liquid crystal display device, is reduced.

  In response to such a problem, Japanese Patent Application Laid-Open No. 2006-53371 (Patent Document 7) relating to the present applicant's application discloses that an uneven surface is formed by hitting fine particles on a polished metal surface, and electroless nickel plating is formed thereon. The anti-glare film having a low haze and a reflection profile of a predetermined value can be obtained by transferring the uneven surface of the mold to a transparent resin film. It is disclosed.

JP 10-54982 A (Claim 1) JP-A-11-133408 (Claim 1) Japanese Patent Laying-Open No. 2005-309110 (Claim 1) JP-A-7-230007 (Claim 1) JP 2002-189106 A (Claims 1 and 5) JP-A-2004-90187 (Claims 1 and 2) JP 2006-53371 A (Claims 1 and 2)

  The present inventors have attempted to further improve the viewing angle characteristics of the above IPS mode liquid crystal display device and apply an antiglare film having an improved reflection profile as disclosed in Patent Document 7. Based on the basics, we have been conducting research to further improve anti-glare performance. As a result, the polarizing plate is disposed above and below the IPS mode liquid crystal cell, and at least one retardation plate is disposed between the back-side polarizing plate and the cell substrate. The retardation value of the birefringent layer existing between the liquid crystal cell side surface and the back side substrate surface of the liquid crystal cell is set within a predetermined range, and the polarizer constituting the front side polarizing plate from the liquid crystal cell side surface to the front surface of the liquid crystal cell By disposing an antiglare layer that gives specific optical characteristics and has a specific surface shape on the display surface side, that is, the visual recognition side, close to zero in the thickness direction retardation value to the side substrate surface The inventors have found that the contrast and the like are further improved, and have completed the present invention.

  Accordingly, an object of the present invention is to provide a high degree of antiglare property by improving the viewing angle characteristics and applying an antiglare layer having a low haze value to an IPS mode liquid crystal display device. Another object of the present invention is to provide a set of polarizing plates which can be arranged on both sides of an IPS mode liquid crystal cell to improve viewing angle characteristics and to provide high antiglare properties. .

  That is, the liquid crystal display device according to the present invention includes a liquid crystal cell in which a liquid crystal is sealed between a pair of cell substrates parallel to each other, and the liquid crystal is aligned in parallel and substantially in the same direction. The front side polarizing plate disposed on the viewing side of the liquid crystal and the rear side polarizing plate disposed on the opposite side thereof, and the direction of the molecular major axis of the liquid crystal is parallel to the substrate due to a change in voltage applied to the liquid crystal cell. It is in the so-called IPS mode, which is configured to change and display in the plane.

And at least 1 phase difference plate is arrange | positioned between a back side polarizing plate and a liquid crystal cell, and it exists between the liquid crystal cell side surface of the polarizer which comprises a back side polarizing plate, and the back side substrate surface of a liquid crystal cell. The sum of the thickness direction retardation Rth of the birefringent layer including the retardation plate is in the range of −40 nm to +40 nm, and the sum of the planar retardation R ₀ is in the range of 100 nm to 300 nm.

  The front-side polarizing plate includes a polarizer and at least a viewing-side transparent protective layer provided on the opposite side of the surface facing the liquid crystal cell, and the front-side substrate surface of the liquid crystal cell from the liquid crystal cell-side surface of the polarizer The thickness direction retardation Rth in the range from -10 nm to +40 nm.

The viewing-side transparent protective layer has fine irregularities on the surface, has a haze of 5% or less with respect to normal incident light, and has a width of 0.5 mm, 1.0 mm, and 2.0 mm between the dark part and the bright part. The total reflection sharpness measured at a light incident angle of 45 ° using three types of optical combs is 50% or less, and the reflectance at a reflection angle of 30 ° for light incident at an incident angle of 30 °. R (30) is 2% or less, reflectance R (40) at a reflection angle of 40 ° is 0.003% or less, and reflectance in an arbitrary direction at a reflection angle of 60 ° or more is R (60 or more). 60 or more) / R (30) value is 0.001 or less, and the average area of the polygon formed when the surface is Voronoi divided with the top of the convex portion of the surface unevenness being 50 μm ² or more It has an antiglare layer that is 1,500 μm ² or less.

Here, the plane retardation R ₀ and the thickness direction retardation Rth of the birefringent layer or a retardation plate, in each film, the refractive index in a slow axis direction in a plane and n _x, the slow axis in the plane the refractive index of the orthogonal directions n _y, the refractive index n _z in the thickness direction and the film thickness when the d,, in which each is defined by the following equation (1) and (2).

_{R 0 = (n x -n y} ) × d (1)
_Rth = [( _nx + _ny ) / 2- _nz ] * d (2)

In other words, the plane retardation R ₀ is a value obtained by multiplying the in-plane refractive index difference by the film thickness, and the thickness direction phase difference Rth is the difference between the in-plane average refractive index and the thickness direction refractive index. The value multiplied by the thickness.

  In the liquid crystal display device of the present invention described above, the front side polarizing plate may have a transparent protective layer on the liquid crystal cell side surface of the polarizer, or may not have a transparent protective layer on the cell side. Also good. When the front side polarizing plate has a transparent protective layer on the liquid crystal cell side surface of the polarizer, the transparent protective layer is made of a cellulose acetate resin or a norbornene resin, and its thickness direction retardation Rth is from −10 nm to +10 nm. It is preferable to be in the range.

Further, the antiglare layer of the preferably have an average area of a polygon formed the surface vertex of the convex portion of the uneven surface as a base point when the Voronoi division is 300 [mu] m ² or more 1,000 .mu.m ² or less .

  For example, the antiglare layer is formed by bumping fine particles on the polished metal surface to form irregularities, and electroless nickel plating is applied to the irregular surface of the metal to form a mold, and the irregular surface of the mold is transparent. It can be comprised by the resin film which has the fine unevenness | corrugation obtained by transferring to a resin film and peeling the transparent resin film in which the uneven surface was transferred next from a metal mold | die. This transparent resin film may be constituted by, for example, applying an ultraviolet curable resin to the surface of a transparent film substrate, transferring the unevenness of the mold to the surface of the ultraviolet curable resin, and curing it. it can. Moreover, this transparent resin film may be composed of, for example, a transparent thermoplastic resin, and the mold irregularities may be thermally transferred to the surface thereof.

  Furthermore, according to this invention, the set of the upper and lower polarizing plates integrated in a liquid crystal display device is also provided, and this polarizing plate set combines the 1st polarizing plate and the 2nd polarizing plate which are shown below.

That is, the first polarizing plate includes a polarizer and a transparent protective layer provided on at least one surface thereof, and the transparent protective layer provided on one surface of the polarizer has fine irregularities on the surface. The thickness direction retardation Rth from the polarizer surface on the side where the antiglare layer of the polarizer is not provided to the outermost surface thereof is in the range of −10 nm to +40 nm. The glare layer has a light incident angle of 45 ° using three types of optical combs with a haze of 5% or less for normal incident light and a width of 0.5 mm, 1.0 mm, and 2.0 mm in the dark and bright areas. The total reflection sharpness measured in (1) is 50% or less. For light incident at an incident angle of 30 °, the reflectance R (30) at a reflection angle of 30 ° is 2% or less and the reflection is at a reflection angle of 40 °. The reflectance R (40) is 0.003% or less and the reflectance in an arbitrary direction with a reflection angle of 60 ° or more is R (60 As above, the value of R (60 or more) / R (30) is 0.001 or less, and the polygon formed when the surface is Voronoi-divided with the vertex of the convex portion of the surface unevenness as the base point average area is 50 [mu] m ² or more 1,500 ² below.

The second polarizing plate includes a polarizer and a retardation plate, and includes a birefringent layer including the retardation plate existing between the retardation plate side surface of the polarizer and the opposite surface of the retardation plate. The sum of the thickness direction retardation Rth is in the range of −40 nm to +40 nm, and the sum of the planar retardation R ₀ is in the range of 100 nm to 300 nm.

  In this set of polarizing plates, the first polarizing plate is usually disposed on the front side (viewing side) of the liquid crystal cell, and the second polarizing plate is disposed on the back side of the liquid crystal cell. The first polarizing plate may have a transparent protective layer on the surface on which the antiglare layer is not provided, or may not have a transparent protective layer there. When the transparent protective layer is provided on the side where the antiglare layer is not provided, the thickness direction retardation Rth up to the outermost surface including the protective layer is set in the range of −10 nm to +40 nm. In the set of polarizing plates, an adhesive layer is provided on the outermost surface of the first polarizing plate on the side where the antiglare layer is not provided and the outermost surface of the second polarizing plate on the retardation plate side. The liquid crystal cell can be bonded to both front and back surfaces.

  Since the liquid crystal display device of the present invention can highly compensate for the phase difference due to the liquid crystal layer and the polarizing plate compared to the liquid crystal display device of the conventional configuration, light leakage due to the viewing angle is suppressed, and the contrast viewing angle is widened. Color shift due to viewing angle can also be suppressed. In addition, the liquid crystal display device exhibits high antiglare properties and suppresses the haze of the antiglare layer used therein, so that it has high contrast, is bright, and has excellent visibility. Furthermore, according to this invention, the set of the polarizing plate used suitably for such a liquid crystal display device is also provided.

  Hereinafter, the present invention will be described in detail with appropriate reference to the accompanying drawings. First, the principle of the IPS mode will be described with reference to FIGS. FIG. 1 is a schematic cross-sectional view showing a configuration example of an IPS mode liquid crystal display device, and FIG. 2 is a schematic perspective view showing an example of normally black in order to explain the principle of the IPS mode. (A) shows a state when no voltage is applied, and (B) shows a state when a voltage is applied. In FIG. 2, the layers are displayed separately for easy understanding. Further, in FIG. 2B, only parts that are in a different state from (A) are given reference numerals, and parts in the same state as in (A) are also given reference numerals in order to avoid difficulty in viewing the drawing. Omitted.

  Referring to FIG. 1, a liquid crystal cell 10 that forms the center of an IPS mode liquid crystal display device has a liquid crystal layer 14 sandwiched between a pair of cell substrates 11 and 13. The liquid crystal molecules 15 constituting the liquid crystal layer 14 are aligned substantially parallel to the surfaces of the cell substrates 11 and 13. Then, the polarizing plates 20 and 30 are arranged with the liquid crystal cell 10 interposed therebetween, and the light between the liquid crystal cell 10 and the backlight 80 out of the light from the backlight 80 arranged on one outer side (back side) thereof. Only linearly polarized light parallel to the transmission axis of the polarizing plate 20 is incident on the liquid crystal cell 10.

  Next, in the state where no voltage is applied as shown in FIG. 2A, the liquid crystal molecules 15 are aligned parallel to the substrate surface and in substantially the same direction. In this example, the liquid crystal molecules 15 are aligned in a direction substantially parallel to the transmission axis 25 of the back-side polarizing plate 20. One substrate (in this example, the lower substrate) 11 is provided with electrodes 12 in parallel in a comb shape. In this state, the linearly polarized light 16 transmitted through the back side polarizing plate 20 passes through the liquid crystal layer 14 without changing its polarization state, and passes through the upper substrate 13 in the state of the linearly polarized light 17 in the same direction as the incident light. To do. If the transmission axis 35 of the front polarizing plate 30 disposed thereon is orthogonal to the transmission axis 25 of the rear polarizing plate 20, the linearly polarized light 17 a that has passed through the upper substrate 13 passes through the front polarizing plate 30. It is not possible to display a black state.

  On the other hand, as shown in FIG. 2B, when an electric field 18 indicated by a broken line is applied between the electrodes 12 and 12 arranged in parallel on the substrate surface, the major axis of the liquid crystal molecules 15 18 and is displaced from the transmission axis 22 of the back-side polarizing plate 20. As a result, the polarization state changes while the incident linearly polarized light 16 passes through the liquid crystal layer 14, and after passing through the liquid crystal layer, an elliptically polarized light 17 b is generated, and a component that can pass through the transmission axis 35 of the front polarizing plate 30 is generated. Thus, the bright state is displayed.

  In FIG. 2, the transmission axis 25 of the back side polarizing plate 20 is arranged so as to be substantially parallel to the long axis of the liquid crystal molecules 15, and the transmission axes of the back side polarizing plate 20 and the front side polarizing plate 30 are orthogonal to each other. However, the transmission axis 35 of the front-side polarizing plate 30 is arranged so as to be substantially parallel to the long axis of the liquid crystal molecules 15, and the transmission axes of the polarizing plates 20 and 30 sandwiching the liquid crystal cell are orthogonal to each other. Even if it arrange | positions in this way, the same result is obtained. In short, the liquid crystal molecules 15 may be arranged so that the major axis thereof is substantially parallel to the transmission axis of one of the polarizing plates. At this time, the major axis direction of the liquid crystal molecules 15 and the transmission axis of one of the polarizing plates do not need to be strictly parallel, but rather the liquid crystal molecules 15 rotate in a certain direction when the electric field 18 is applied. The angle may be shifted by a certain angle, for example, an angle within 10 °. Further, by arranging the pair of polarizing plates 20 and 30 so that the transmission axes are orthogonal to each other, the so-called normally black is often displayed in which a black state is displayed when no voltage is applied and a bright state is displayed when a voltage is applied. However, if the transmission axes of the pair of polarizing plates 20 and 30 are arranged in parallel, a so-called normally white is displayed in which a bright state is displayed when no voltage is applied and a black state is displayed when a voltage is applied.

  The present invention improves the viewing angle and the antiglare property of the IPS mode liquid crystal display device shown in FIG. 1 and FIG. 2, and an example of the layer structure is shown in FIG. This is shown schematically. In this example, a front side polarizing plate 30 is disposed on the viewing side of the liquid crystal cell 10, and a back side polarizing plate 20 is disposed on the opposite side. The liquid crystal cell 10 is the same as that described above with reference to FIG. 1, and a liquid crystal is sealed between a pair of parallel cell substrates 11 and 13 to form a liquid crystal layer 14. In the liquid crystal layer 14, the liquid crystal is aligned substantially parallel to and substantially in the same direction as the substrates 11 and 13 when no voltage is applied. The direction of the molecular long axis of the liquid crystal changes in a plane parallel to the substrate due to a change in the voltage applied to the liquid crystal cell, and display is performed. The back side polarizing plate 20 has a configuration in which transparent protective layers 22 and 23 are arranged with a polarizer 21 in between. 3A shows an example in which a transparent protective layer 33 is provided on one side of the viewing side of the polarizer 31, and FIG. 3B shows the polarizer 31. In this example, a transparent protective layer 32 is provided on the cell side surface, and a transparent protective layer 33 is also provided on the viewing side surface. 3A and 3B only differ in the configuration of the front-side polarizing plate 30. FIG.

At least one phase difference plate 40 is disposed between the back side polarizing plate 20 and the liquid crystal cell 10, and the back side substrate 11 of the liquid crystal cell 10 from the surface on the liquid crystal cell side of the polarizer 21 constituting the back side polarizing plate 20. The sum of the thickness direction retardation Rth of the birefringent layer including the retardation plate 40 existing up to the surface is in the range of −40 nm to +40 nm, and the sum of the planar retardation R ₀ is 100 nm to 300 nm. Try to be in range.

  The front-side polarizing plate 30 includes a polarizer 31 and a viewing-side transparent protective layer 33 provided at least on the side opposite to the surface facing the liquid crystal cell 10. The surface of the polarizer 31 facing the liquid crystal cell 10 may not be provided with a transparent protective layer as shown in FIG. 3A, and the polarizer 31 may be directly bonded to the cell substrate 13, or FIG. A transparent protective layer 32 may be provided as in B). When the polarizer 31 is directly bonded to the cell substrate 13, the phase difference between the polarizer 31 and the front substrate 13 of the liquid crystal cell is zero, but the polarizer 31 is as shown in FIG. Even when the transparent protective layer 32 exists between the front surface side substrate 13 and the other surface, the space between the surface of the polarizer 31 on the liquid crystal cell 10 side and the surface of the front surface side substrate 13 of the liquid crystal cell is present. The thickness direction retardation Rth is set in the range of −10 nm to +40 nm.

Further, the viewing-side transparent protective layer 33 has an anti-glare layer 50 having fine irregularities formed on the surface, and this anti-glare layer 50 has a haze of 5% or less for normal incident light, and is a dark part. And the total reflection sharpness measured at a light incident angle of 45 ° using three types of optical combs having a width of 0.5 mm, 1.0 mm and 2.0 mm, and less than 50%. For light incident at an incident angle of 30 °, the reflectance R (30) at a reflection angle of 30 ° is 2% or less, the reflectance R (40) at a reflection angle of 40 ° is 0.003% or less, and the reflection angle is 60 °. The reflectance in the above arbitrary direction is R (60 or more), the value of R (60 or more) / R (30) is 0.001 or less, and the surface of the surface with the vertex of the convex part of the surface unevenness as the mother point an average area of a polygon formed when Voronoi division and is 50 [mu] m ² or more 1,500 ² or less It is configured. In FIG. 3, the antiglare layer 50 is shown to be integrated with the viewing-side transparent protective layer 33 constituting the front-side polarizing plate 30, and such a configuration is preferable, but on the polarizer 31. Of course, a configuration in which a transparent protective layer is provided and an antiglare layer is provided thereon may be used. The antiglare layer 50 will be described in detail later.

  Adhesives 48 are usually attached between the back side polarizing plate 20 and the phase difference plate 40, between the phase difference plate 40 and the liquid crystal cell 10, and between the front side polarizing plate 30 and the liquid crystal cell 10, respectively. Is done. As the pressure-sensitive adhesive 48, an acrylic material having excellent transparency is generally used. A backlight 80 for supplying light to the liquid crystal cell 10 is usually provided on the back side of the back side polarizing plate 20.

  The pair of polarizers 21 and 31 may be of a type generally known as a polarizing film that transmits linearly polarized light that vibrates in one direction orthogonal to each other in the film plane and absorbs linearly polarized light that vibrates in the other direction. . Specifically, it is possible to use a polyvinyl alcohol-based resin film that has been uniaxially stretched and dyed with a high dichroic dye, and further subjected to boric acid crosslinking. There are iodine-based polarizers using iodine as the high-dichroic dye and dye-based polarizers using dichroic organic dyes as the high-dichroic dye, both of which can be used. In a polyvinyl alcohol polarizer subjected to such stretching and dyeing, the stretching direction is the absorption axis, and the direction perpendicular to it in the plane is the transmission axis.

  When the transparent protective layers 22 and 23 are provided on both surfaces of the polarizer 21 as shown for the back-side polarizing plate 20, or as shown for the front-side polarizing plate 30, the transparent protective layers 32 and 23 are provided on one or both sides of the polarizer 31. In the case of providing 33, these transparent protective layers are generally composed of a transparent resin film, for example, cellulose acetate resins such as triacetyl cellulose, polycyclic cyclic olefins such as norbornene and dimethanooctahydronaphthalene. A cyclic olefin resin, a polycarbonate resin, or the like having a main monomer as the monomer is used. Among these, cellulose acetate resins (particularly triacetyl cellulose) and cyclic olefin resins are preferably used. Commercial products of cyclic olefin-based resins include “Arton” sold by JSR Corporation, “Zeonor” and “Zeonex” (all trade names) sold by Nippon Zeon Corporation.

On the back side of the liquid crystal cell 10, at least one retardation plate 40 is disposed between the back side polarizing plate 20 and the liquid crystal cell 10, and the back side substrate of the liquid crystal cell 10 from the liquid crystal cell side surface of the back side polarizer 21. The sum of the thickness direction retardation Rth of the birefringent layer including the retardation plate 40 existing up to 11 surfaces is in the range of −40 nm to +40 nm, and the sum of the planar retardation R ₀ is 100 nm to 300 nm. Try to be in range. If the sum of Rth exceeds ± 40 nm, the color shift due to the viewing angle increases, which is not preferable. If the sum of _R0 is out of this range, both the luminance and the color shift due to the viewing angle deteriorate, which is not preferable.

If the back side polarizing plate 20 has a liquid crystal cell 10 side transparent protective layer on the surface 22 of the polarizer 21, the transparent protective layer is generally planar retardation similar principal refractive indices n _x and n _y are in-plane little, refractive index n _z in the thickness direction is slightly smaller than the principal refractive indices n _x and n _y in the plane, has a negative uniaxial property, its optical axis appears in a direction substantially normal, so-called negative C- It becomes a plate. In the negative C-plate, the thickness direction retardation Rth takes a positive value. In such a case, as the retardation plate 40 disposed between the back side polarizer 20 and the liquid crystal cell 10 has an n _x ≧ n _z> n _y or n _z> n _x> n _y becomes refractive index structure The thickness direction retardation Rth may be substantially zero or negative so as to satisfy the above condition in combination with the thickness direction retardation of the transparent protective layer of the polarizing plate. Specifically, as disclosed in Patent Document 4, a thermoplastic resin film having a negative refractive index anisotropy, such as a uniaxially stretched and oriented in the thickness direction, or polystyrene. A so-called negative A-plate (or biaxial) obtained by stretching a resin film uniaxially or biaxially, a so-called positive C-plate having positive uniaxiality and an optical axis in the film normal direction, Examples thereof include a laminate of so-called negative A-plates having negative uniaxiality and an optical axis in a direction parallel to the film surface.

  As is clear from the above description, it is necessary to arrange at least one retardation plate 40, but two or more retardation plates 40 may be used in combination so as to obtain a desired retardation value.

Further, the cell-side transparent protective layer 22 in the back-side polarizing plate 20 can be omitted, and the retardation film 40 can also function as a protective layer for the back-side polarizer 21. In this case, the thickness direction retardation Rth of the retardation plate 40 itself may be in the range of −40 nm to +40 nm, and the planar retardation R ₀ may be in the range of 100 nm to 300 nm. Also in this case, as shown above, the thermoplastic resin film is uniaxially stretched and oriented in the thickness direction, or may be biaxially negative A-plate, positive C-plate and negative A-plate A laminate of these can be used.

  The material of the phase difference plate 40 will be described. As the film in which the thermoplastic resin film is uniaxially stretched and oriented in the thickness direction, a polycarbonate resin is preferably used. As the negative A-plate, a styrene resin, N-phenylmaleimide / α-olefin copolymer resin, or the like is preferably used. The positive C-plate can be obtained by forming a rod-like liquid crystal compound layer on the vertical alignment film.

Further, the phase difference plate 40 disposed between the back-side polarizing plate 20 and the liquid crystal cell 10 is as defined when _nx , _ny, and _nz are derived from the previous equations (1) and (2). As the three-way refractive index, the Nz coefficient defined by the following formula (3) is preferably in the range of −0.5 to +0.5.

_{Nz = (n x -n z)} / (n x -n y) (3)

The Nz coefficient is a ratio of the difference between the in-plane maximum refractive index (slow axis direction refractive index) and the thickness direction refractive index with respect to the in-plane refractive index difference, and is an index representing the degree of orientation in the thickness direction. For example, the so-called positive A- plate a positive uniaxial optical axis is in the plane _{(n x> n y ≒ n} z), a so-called negative optical axis in the plane in Nz ≒ 1, and the negative uniaxial A- the plate _{(n x ≒ n z> n} y), the Nz ≒ 0. In addition, when using the laminated body which consists of several sheets as the phase difference plate 40, it is preferable that the Nz coefficient as the whole laminated body exists in the said range.

  In the case where a laminate composed of a plurality of sheets is used as the phase difference plate 40 and at least two of them show a plane phase difference, the slow axes of the phase difference plates showing the plane phase difference are in the same direction. By laminating in such a manner, it is usual that the planar phase difference of the entire laminate is the sum of the respective planar phase difference values. The same applies to the case where the back-side polarizing plate 20 has the cell-side transparent protective layer 22, and when the cell-side transparent protective layer 22 of the back-side polarizing plate 20 exhibits a planar phase difference, its slow axis and retardation plate It is usual to laminate so that the 40 slow axes are in the same direction. However, if the planar phase difference of the transparent protective layer 22 is, for example, about 5 nm or less, the value can be practically ignored, so the slow axis direction does not have to be particularly concerned. In addition, the thickness direction retardation as the whole laminated body becomes the sum of the thickness direction retardation which each laminated | stacked phase difference plate shows.

  In addition, on the front side of the liquid crystal cell 10, a retardation plate may be provided between the front side polarizing plate 30 and the liquid crystal cell 10 as desired. Even in such a case, the polarization constituting the front side polarizing plate 30. The thickness direction retardation Rth from the liquid crystal cell side surface of the element 31 to the front side substrate 13 of the liquid crystal cell 10 is set to be in the range of −10 nm to +40 nm. When the thickness direction retardation value between the liquid crystal cell-side surface of the front-side polarizer 31 and the front-side substrate 13 of the liquid crystal cell 10 is outside this range, color compensation by the retardation plate 40 disposed on the back side is appropriate. Therefore, there is a strong tendency for the bluish color to increase when the screen is viewed obliquely.

  In the case where a retardation plate is not disposed on the front side of the liquid crystal cell 10 and a front side polarizing plate 30 having a transparent protective layer 32 on the cell side as shown in FIG. The birefringent layer existing between the liquid crystal cell side surface of the polarizer 31 and the front side substrate 13 of the liquid crystal cell 10 is only the cell side transparent protective layer 32 of the front side polarizing plate 30. In this case, the thickness direction retardation Rth of the cell-side transparent protective layer 32 may be set in the range of −10 nm to +40 nm, and particularly preferably in the range of −10 nm to +10 nm, and more preferably in the range of −5 nm to +5 nm. . For example, in the case of a cyclic olefin resin film, a film that is substantially non-oriented and has a thickness direction retardation Rth of 10 nm or less, and further 5 nm or less is available from the market. In addition, for cellulose acetate resin films such as triacetyl cellulose, films that are substantially non-oriented and have a thickness direction retardation Rth of 10 nm or less, and further 5 nm or less are available from the market. Further, even a solvent cast film of a cellulose acetate resin film such as triacetyl cellulose, a thin film has a thickness direction retardation Rth of 40 nm or less.

  Moreover, the transparent protective layer is not provided on the cell side of the front side polarizing plate 30, and the polarizer 31 can be directly attached to the front side substrate 13 of the liquid crystal cell 10 via the adhesive 48 or the like. In this case, the thickness direction retardation Rth from the liquid crystal cell side surface of the front polarizer 31 to the front substrate 13 of the liquid crystal cell 10 is substantially zero.

The retardation value of the film is, for example, a commercially available retardation measuring device such as “KOBRA-21ADH” manufactured by Oji Scientific Instruments Co., Ltd., with the film to be measured bonded to a glass plate via an adhesive. It is possible to directly measure using In the phase difference measuring apparatus as described above, for example, the plane phase difference Ro of the film is measured by a rotating analyzer method using monochromatic light with a wavelength of 559 nm, while the in-plane slow axis of the film is used as the tilt axis. The retardation value R ₄₀ when tilted by 40 degrees is measured, and numerical calculation is performed from the following formulas (1), (4) and (5) using the film thickness d and the average refractive index n ₀ of the film. _nx , _ny, and _nz are obtained, and these are substituted into the equation (2) to calculate the thickness direction retardation Rth. Equation (1) is the same as that shown above.

_{R 0 = (n x -n y} ) × d (1)
R ₄₀ = (n _x −ny _y ) × d / cos (φ) (4)
(n _x + _ny + _nz ) / 3 = n ₀ (5)
here,
φ = sin ^-1 [sin (40 °) / n ₀ ]
n _y ′ = _ny × _nz / [ _ny ² × sin ² (φ) + _nz ² × cos ² (φ)] ^1/2

  In the liquid crystal display device of the present invention, the back-side polarizing plate 20 and the front-side polarizing plate 30 are usually arranged so that their absorption axes are orthogonal to each other and are normally black. Further, the retardation plate 40 disposed between the back side polarizing plate 20 and the liquid crystal cell 10 may be disposed so that the slow axis thereof is substantially parallel or substantially orthogonal to the absorption axis of the back side polarizing plate 20. In particular, it is preferable to arrange them so as to be substantially orthogonal. Further, the retardation film 40 is preferably arranged so as to be substantially parallel to the slow axis of the liquid crystal layer 14 in the liquid crystal cell 10 in the state where no voltage is applied, that is, the major axis direction of the liquid crystal molecules. Such a preferred axial relationship is shown in a schematic perspective view in FIG. In this example, the absorption axis 26 of the back side polarizing plate 20 is substantially orthogonal to the slow axis (long axis of liquid crystal molecules) 19 of the liquid crystal layer when no voltage is applied in the liquid crystal cell 10, The slow axes of the retardation plates 40 arranged between the liquid crystal cells 10 are substantially parallel, and the absorption axis 36 of the front side polarizing plate 30 is substantially parallel. Inevitably, the absorption axis 26 of the back-side polarizing plate 20 and the absorption axis 36 of the front-side polarizing plate 30 are in an orthogonal relationship. Here, the absorption axes 26 and 36 of the polarizing plates 20 and 30 are orthogonal to the transmission axes 25 and 26 shown in FIG.

  In this specification, “substantially” in the case of “substantially parallel” or “substantially orthogonal” means that an angle of about ± 10 ° is allowed around the arrangement (parallel or orthogonal) described there. .

In the present invention, a predetermined optical characteristic is given to the surface opposite to the side facing the liquid crystal cell 10 of the polarizer 31 constituting the front side polarizing plate 30, that is, the surface on the display surface (viewing) side. An antiglare layer 50 having a surface shape of is arranged. This anti-glare layer 50 has an anti-glare surface having a large number of fine irregularities formed on the surface, has a haze of 5% or less with respect to perpendicular incident light, and has a width of 0.5 mm and 1. The total reflection sharpness measured at an incident angle of 45 ° using three types of optical combs of 0 mm and 2.0 mm is less than 50%. The reflectance R (30) at 30 ° is 2% or less, the reflectance R (40) at a reflection angle of 40 ° is 0.003% or less, and the reflectance in an arbitrary direction with a reflection angle of 60 ° or more is R (60 As described above, the value of R (60 or more) / R (30) is 0.001 or less, and the polygon formed when the surface is Voronoi-divided with the vertex of the convex portion of the surface unevenness as the base point average area is 50 [mu] m ² or more 1,500 ² below. The average area of the polygon formed when this Voronoi is divided is preferably 300 μm ² or more, and more preferably 1,000 μm ² or less.

  The antiglare layer 50 will be described in detail. The antiglare layer 50 has an antiglare surface with fine irregularities formed on the surface, and has a haze of 5% or less with respect to light incident from the vertical direction. As described above, the anti-glare layer 50 can suppress a decrease in contrast when applied to a liquid crystal display device by suppressing the haze even though the surface has irregularities and has anti-glare performance. it can.

  In addition, the antiglare layer 50 has a reflection definition with respect to 45 ° incident light of 50% or less. Reflection sharpness is measured by the method specified in JIS K 7105. In this JIS, as an optical comb used for measurement of image definition, the ratio of the width of the dark part to the bright part is 1: 1, and the widths are 0.125 mm, 0.5 mm, 1.0 mm and 2.0 mm. The type is specified. Among these, when an optical comb having a width of 0.125 mm is used, the antiglare layer defined in the present invention has a small reflection definition and a large error in the measured value. Therefore, an optical comb having a width of 0.125 mm is used. Measured values when using, do not add to the sum, and reflectivity with the sum of image sharpness measured using three types of optical combs with widths of 0.5 mm, 1.0 mm, and 2.0 mm I will call it. In this definition, the maximum value of the reflection definition is 300%. When the reflection definition according to this definition exceeds 50%, an image of a light source or the like is reflected, and the antiglare property is deteriorated.

  However, when the reflection definition is 50% or less, it is difficult to determine the superiority or inferiority of the antiglare property only from the reflection definition. Because, when the reflection definition according to the above definition is 50% or less, each reflection definition using optical combs of width 0.5 mm, 1.0 mm, and 2.0 mm is about 10% to 20%. This is because the fluctuation of the reflection definition due to measurement error or the like cannot be ignored.

  Therefore, the angle dependence of the reflectance adopted as another index for determining the antiglare performance will be described with reference to FIGS. FIG. 5 is a perspective view schematically showing a light incident direction and a reflection direction with respect to the antiglare layer (antiglare film). In the present invention, with respect to the incident light 56 incident at an angle of 30 ° from the normal line 55 of the antiglare layer 10, the reflectance of the reflected light in the direction of the reflection angle of 30 °, that is, the regular reflection direction 57 (that is, normal When the reflectance is R (30), R (30) is set to 2% or less. The regular reflectance R (30) is 1.5% or less, more preferably 1% or less. When the regular reflectance R (30) exceeds 2%, a sufficient antiglare function cannot be obtained, and the visibility is deteriorated. In FIG. 5, the direction of the reflected light at an arbitrary reflection angle θ is represented by reference numeral 58, and the directions 57 and 58 of the reflected light when measuring the reflectance are the incident light direction 56, the film normal 55, and the like. In the plane 59 including

  FIG. 6 is an example of a graph in which the reflection angle and the reflectance (the reflectance is a logarithmic scale) of the reflected light 58 with respect to the incident light 56 incident at an angle of 30 ° from the normal line 55 of the antiglare layer 50 in FIG. is there. Such a graph representing the relationship between the reflection angle and the reflectance, or the reflectance for each reflection angle read from the graph may be referred to as a reflection profile. As shown in this graph, the regular reflectance R (30) is the peak of the reflectance with respect to the incident light 56 incident at 30 °, and the reflectance tends to decrease as the distance from the regular reflection direction increases.

  Further, in the present invention, when the reflectance at a reflection angle of 40 ° is R (40) with respect to the incident light 56 incident at an angle of 30 ° from the normal line 55 of the antiglare layer 50 in FIG. It shall be 0.003% or less. If R (40) exceeds 0.003%, whitening tends to occur. Therefore, it is preferable that R (40) is not so large. On the other hand, if R (40) is too small, sufficient anti-glare properties will not be exhibited, so generally it is preferably 0.00005% or more. However, it is difficult to strictly define the preferable range of R (40). This is because reflection and whitishness are subjective evaluations by visual observation and are characteristics that ultimately reflect consumer preferences.

  Furthermore, in the present invention, when the reflectance in an arbitrary direction having a reflection angle of 60 ° or more is R (60 or more) with respect to incident light 56 incident at an angle of 30 ° from the normal line 55 of the antiglare layer 50 in FIG. In addition, the value of R (60 or more) / R (30) is set to 0.001 or less. R (60 or more) / R (30) is preferably 0.0005 or less, more preferably 0.0002 or less. Here, the arbitrary direction having a reflection angle of 60 ° or more is specifically a reflection angle between 60 ° and 90 °, and the antiglare film produced by the method described later has a typical reflection profile. As shown in FIG. 6, the reflectance in the regular reflection direction is a peak, and the reflectance often decreases as the reflection angle increases. In this case, the reflectance at a reflection angle of 60 ° is R (60). As R (60) / R (30), the value of R (60 or more) / R (30) can be represented. When the value of R (60 or more) / R (30) exceeds 0.001, whitening occurs in the antiglare layer, and visibility decreases. That is, for example, even when black is displayed on the display surface with the anti-glare layer disposed on the forefront of the display device, a whitish color occurs that picks up light from the surroundings and makes the display surface entirely white. .

  In the example of the reflection profile shown in FIG. 6, the regular reflectance R (30) is about 0.4%, R (40) is about 0.0006%, and R (60) is about 0.00003%. .

In addition to the reflection profile described above, the antiglare layer has, as a shape factor, an average area of polygons formed when the surface is Voronoi divided with the apex of the convex portion of the surface unevenness being 50 μm ² or more. 1,500 ² or less, preferably to satisfy that is 300 [mu] m ² or more 1,000 .mu.m ² or less.

  First, an algorithm for obtaining the apex of the convex portion on the uneven surface of the antiglare layer will be described. When an arbitrary point on the surface of the antiglare layer is focused, there is no point higher than the focused point around that point, and the altitude of the uneven surface of that point is the highest point of the uneven surface If the altitude is higher than the middle of the altitude of the lowest point, that point is the vertex of the convex portion. FIG. 7 is a perspective view schematically showing an algorithm for determining a convex portion of an antiglare film. More specifically, based on this figure, attention is paid to an arbitrary point 61 on the surface of the antiglare layer, and a circle having a radius of 2 μm to 5 μm parallel to the reference surface 63 of the antiglare layer is drawn around the point 61. When the point on the anti-glare layer surface 62 included in the projection surface 64 of the circle does not have a point higher than the point 61 of interest, and the height of the uneven surface of the point is uneven If the elevation is higher than the middle between the highest point and the lowest point, the point 61 is determined to be the apex of the convex portion. At this time, the radius of the circle 64 is required to be a size that does not count fine irregularities on the sample surface and does not include a plurality of convex portions, and is preferably about 3 μm. According to this method, the number of convex portions per unit surface area of the concavo-convex surface can be determined.

  The number of vertices of the protrusions required here is 50 or more and 150 or less in a 200 μm × 200 μm region in order to express good visibility without causing reflection or whitening. Is preferred. If the number of convex portions on the concave / convex surface is small, glare due to interference with pixels occurs when used in combination with a high-definition image display device, which is not preferable. Further, when the number of convex portions is small, the texture is also lowered. On the other hand, when the number of convex portions is excessively large, as a result, the inclination angle of the surface concavo-convex shape becomes steep, and whitening is likely to occur. The number of convex portions in the 200 μm × 200 μm region is preferably 120 or less, and more preferably 70 or more.

  Next, Voronoi division is explained. When several points (called mother points) are arranged on a plane, the plane is divided according to which mother point is closest to any point in the plane. A figure that can be called a Voronoi diagram, and that division is called Voronoi division. FIG. 8 is an example in which the surface of the antiglare layer surface unevenness is Voronoi divided with the apex of the convex portion as a base point. In FIG. 8, square points 65 and 65 are generating points, and individual polygons 66 and 66 including one generating point are regions formed by Voronoi division, and are called Voronoi regions or Voronoi polygons. In the following, it is called a Voronoi polygon. In this figure, the peripherally thinned portions 67 and 67 will be described later. In the Voronoi diagram, the number of generating points coincides with the number of Voronoi polygons. In FIG. 8, only some of the generating points and Voronoi polygons are provided with leading lines and symbols. However, the fact that there are a large number of generating points and Voronoi polygons is explained above and this figure. Will be easily understood.

  When calculating the average area of Voronoi polygons obtained by performing Voronoi division using the top of the convex part as the base point, the surface shape is measured using a confocal microscope, interference microscope, atomic force microscope (AFM), etc. Then, after obtaining the three-dimensional coordinate value of each point on the surface of the antiglare layer, Voronoi division is performed by the following algorithm to obtain the average area of the Voronoi polygon. That is, according to the algorithm described above, first, the vertex of the convex portion on the uneven surface of the antiglare layer is obtained, and then the vertex of the convex portion is projected onto the reference surface of the antiglare layer. After that, all three-dimensional coordinates obtained by measuring the surface shape are projected onto the reference plane, and all the projected points are assigned to the nearest base point to perform Voronoi division. The area of each polygon is calculated and averaged to obtain the average area of the Voronoi polygon. In the measurement, in order to reduce the error, the Voronoi polygon that touches the boundary of the measurement visual field is not included. That is, in FIG. 8, the Voronoi polygons 67 and 67 that are in contact with the boundary of the visual field and are thinly painted are not counted in the calculation of the average area. Moreover, in order to reduce a measurement error, it is preferable to measure three or more areas of 200 μm × 200 μm or more and use the average value as a measured value.

In the present invention, as described above, so that the average area of a polygon formed an apex of the convex portion of the concavo-convex surface when Voronoi dividing the surface as a base point, a 50 [mu] m ² or more 1,500 ² or less To. Preferably, the average area of the Voronoi polygon is made to be 300 [mu] m ² or more 1,000 .mu.m ² or less. When the average area of the Voronoi polygon is less than 50 μm ² , the inclination angle of the surface of the antiglare layer becomes steep, and as a result, whitening tends to occur, which is not preferable. On the other hand, when the average area of the Voronoi polygon is larger than 1,500 μm ² , the uneven surface shape becomes rough, and glare is likely to occur when applied to a recent high-definition image display device, and the texture is also reduced. Therefore, it is not preferable.

  By using the three-dimensional coordinates measured here, it is possible to calculate the arithmetic average height Pa and the maximum cross-sectional height Pt of the cross-sectional curve defined in JIS B 0601 (= ISO 4287). It is also possible to represent the elevation of each point on the uneven surface of the antiglare layer with a histogram. Here, in order to express good visibility without causing reflection or whiteness, the arithmetic average height Pa of the cross-sectional curve is preferably 0.08 μm or more and 0.15 μm or less, and the maximum cross-sectional height is The thickness Pt is preferably 0.4 μm or more and 0.9 μm or less. When the arithmetic average height Pa in the cross-sectional curve of the uneven surface is less than 0.08 μm, the surface of the antiglare layer tends to be almost flat and does not exhibit sufficient antiglare performance. When the arithmetic average height Pa in the cross-sectional curve is larger than 0.15 μm, the surface shape becomes rough, and problems such as whitishness and glare tend to occur. On the other hand, when the maximum cross-sectional height Pt in the cross-sectional curve of the concavo-convex surface is less than 0.4 μm, the anti-glare layer surface is also almost flat and does not show sufficient anti-glare performance. When the maximum cross-sectional height Pt in the cross-sectional curve is larger than 0.9 μm, the surface shape becomes too rough, and problems such as whitishness and glare tend to occur.

  In addition, when the elevation of each point on the uneven surface of the antiglare layer is represented by a histogram, the peak of the histogram is the midpoint (50% height) between the highest point (height 100%) and the lowest point (height 0%). It is preferable that it exists in the range within +/- 20% centering on. This means that the peak of the histogram is preferably in the range of 30% to 70% with respect to the difference between the highest and lowest points (maximum elevation). If no peak is present within ± 20% from the midpoint, in other words, if the peak appears at a position greater than 70% or less than 30% relative to the maximum elevation, the surface shape will be rough as a result. There is a tendency that glare is likely to occur, and the texture of the appearance also tends to be lowered.

  When calculating the elevation histogram, first find the highest and lowest elevations on the surface of the antiglare layer (antiglare film), and then the difference between the elevation of the measurement point and the lowest point (the height of that point) ) Is divided by the difference between the highest and lowest points (maximum elevation) to determine the relative height of each point. By representing the relative height obtained as a histogram with the highest point being 100% and the lowest point being 0%, the peak position of the histogram is obtained. It is necessary to divide the histogram so that the peak position is not affected by data errors, and it is generally appropriate to divide the histogram into about 10 to 30. For example, the lowest point (height 0%) to the highest point (height 100%) may be divided in increments of 5% to obtain the peak position.

  The antiglare surface that constitutes the antiglare layer exhibiting the above characteristics is a shape that is covered with unevenness that has virtually no flat surface. The antiglare surface having such a surface shape is, for example, a bump formed by hitting fine particles on the surface of a polished metal, and electroless nickel plating is applied to the uneven surface of the metal to form a mold. Can be advantageously produced by a method of transferring the uneven surface to a transparent resin film and then peeling the transparent resin film having the uneven surface transferred from the mold.

  A method suitable for producing the antiglare layer (antiglare film) in this manner will be described with reference to FIG. FIG. 9 is a cross-sectional view schematically showing a process for producing an antiglare film by producing a mold having irregularities on the surface and transferring the irregularities to a film, using a metal plate as an example. It is.

  FIG. 9A shows a cross section of the metal substrate 71 after mirror polishing, and a polishing surface 72 is formed on the surface thereof. By applying fine particles to the metal surface after such mirror polishing, irregularities are formed on the surface. FIG. 9B is a schematic cross-sectional view of the metal substrate 71 after hitting the fine particles, and a fine concave surface 73 having a partial spherical shape is formed by hitting the fine particles. Furthermore, the uneven surface of the metal surface is smoothed by performing electroless nickel plating on the surface on which the unevenness due to the fine particles is formed. FIG. 9C is a schematic cross-sectional view after electroless nickel plating. A nickel plating layer 74 is formed on a fine concave surface formed on the metal substrate 71, and the surface 76 thereof has no surface. By electrolytic nickel plating, it is in a state of being loosened compared to the concave surface 73 of (B), in other words, the uneven shape is relaxed. In this way, by applying electroless nickel plating to the partially spherical fine concave surface 73 formed by hitting fine particles on the metal surface, an antiglare film having substantially no flat portion and having preferable optical properties can be obtained. It is possible to obtain a metal mold in which irregularities suitable for obtaining are formed.

  FIG. 9D is a schematic cross-sectional view showing a state in which the unevenness of the mold formed by electroless nickel plating in FIG. 9C is transferred to the film, and the nickel plating layer 74 formed on the metal substrate 71. A resin layer is formed on the concavo-convex surface, and the film 50 having the concavo-convex shape transferred thereon is obtained. The film 50 can be composed of a single thermoplastic transparent resin. In this case, the thermoplastic resin film may be pressed against the uneven surface 76 of the mold in a heated state and shaped by hot pressing. Moreover, the film 50 can also be comprised by what formed the ionizing-radiation-curable resin layer 52 on the surface of the transparent base film 51 so that it may illustrate in FIG.9 (D). By bringing the resin layer 52 into contact with the uneven surface 76 of the mold and irradiating the ionizing radiation to cure the ionizing radiation curable resin layer 52, the uneven shape of the mold is transferred to the ionizing radiation curable resin layer 52. The These films will be described in detail later. (E) of FIG. 9 is a schematic cross-sectional view showing a state where the film 50 formed on the mold in (D) is peeled off from the mold.

  In the method shown in FIG. 9, examples of the metal that can be suitably used for producing the mold include aluminum, iron, copper, and stainless steel. Among these, those in which the metal surface is likely to be deformed by colliding with fine particles, specifically, those having a very low hardness are preferable, and aluminum, iron, copper, etc. are preferably used. From the viewpoint of cost, aluminum and soft iron are more preferable. The metal mold may be a flat metal plate or a cylindrical metal roll. If a metal mold | die is produced using a metal roll, an anti-glare film can be manufactured in a continuous roll shape.

  These metals are hit by fine particles when the surface is polished, but it is particularly preferable that the metal be polished in a state close to a mirror surface. This is because the metal plate and the metal roll are often subjected to machining such as cutting and grinding in order to obtain a desired accuracy, and as a result, the processing surface remains on the metal surface in many cases. . In the state with deep processed eyes, even if the metal surface is deformed by hitting the fine particles, the processed eyes may be deeper than the irregularities formed by the fine particles, and the effects of the processed eyes remain, and the optical characteristics cannot be predicted. May have an effect.

  There is no particular limitation on the method for polishing the metal surface, and any of mechanical polishing, electrolytic polishing, and chemical polishing can be used. Examples of the mechanical polishing method include super finishing, lapping, fluid polishing, and buff polishing. The surface roughness after polishing is preferably represented by a center line average roughness Ra, and Ra is preferably 1 μm or less, more preferably Ra is 0.5 μm or less, and still more preferably Ra is 0.1 μm or less. If the center line average roughness Ra is too large, even if the metal surface is deformed by hitting fine particles, the influence of the surface roughness before deformation may remain, which is not preferable. There is no particular limitation on the lower limit of Ra, but there is no need to specify it because there is a natural limit from the viewpoint of processing time and processing cost.

  As a method of hitting the metal surface with fine particles, an injection processing method is preferably used. Examples of the injection processing method include a sand blast method, a shot blast method, and a liquid honing method. The particles used in these processes are preferably in a shape close to a sphere rather than a shape having sharp corners, and particles of a hard material that are crushed during processing and do not produce sharp corners are preferable. . As particles satisfying these conditions, spherical zirconia beads and alumina beads are preferably used for ceramic particles. For metal particles, beads made of steel or stainless steel are preferred. Furthermore, particles in which ceramic or metal particles are supported on a resin binder may be used.

Here, as the fine particles hitting the metal surface, those having an average particle diameter of 10 to 75 μm, preferably 10 to 35 μm, and in particular, spherical fine particles are used, and the convex portions on the uneven surface as defined in the present invention. vertices is average area of a polygon formed when Voronoi dividing the surface as a base point, 50 [mu] m ² or more 1,500 ² or less, the shape factor preferably including the requirement that 300 [mu] m ² or more 1,000 .mu.m ² or less An antiglare film can be produced. The fine particles are particularly preferably those having a substantially uniform particle size, that is, monodispersed particles. If the average particle size of the fine particles is too small, it is difficult to form sufficient irregularities on the metal surface, and the inclination angle of the surface becomes steep, and whitening tends to occur. On the other hand, if the average particle size of the fine particles is too large, the surface irregularities become rough, and glare occurs or the texture is lowered.

  By applying electroless nickel plating to the metal surface with the irregularities formed in this way, the irregular surface is smoothed to make a metal plate. The degree of unevenness varies depending on the type of base metal, the size and depth of unevenness obtained by techniques such as blasting, and the type and thickness of plating. The biggest factor is the plating thickness. If the thickness of the electroless nickel plating is thin, the effect of smoothing the surface shape of the unevenness obtained by techniques such as blasting cannot be obtained sufficiently, and the optical of the antiglare film obtained by transferring the uneven shape to a transparent film The characteristics are not so good. On the other hand, if the plating thickness is too thick, the productivity will deteriorate. Therefore, the thickness of the electroless nickel plating is preferably about 3 to 70 μm, more preferably 5 μm or more and 50 μm or less.

  Electroless plating capable of plating the surface of a metal plate or metal roll with a uniform thickness as viewed macroscopically, particularly electroless nickel plating with a high hardness of the plating layer is preferably employed. More preferable electroless nickel plating is so-called bright nickel plating using a plating bath containing a brightening agent such as sulfur, nickel-phosphorus alloy plating (low phosphorus type, medium phosphorus type or high phosphorus type), nickel-boron alloy plating. Etc. are exemplified.

  In hard chrome plating, particularly electrolytic chrome plating, employed in Patent Document 5 listed in the Background Art section, electric field concentration occurs at the end of a metal plate or metal roll, and the plating thickness differs between the central portion and the end portion. It will be. Therefore, even if the unevenness is formed at a uniform depth over the entire plate surface by the blasting method, the unevenness of the unevenness after plating differs depending on the location of the plate, and the resulting unevenness depth varies. Therefore, it is not preferable to use electrolytic plating.

  Hard chrome plating is not suitable for the production of a metal mold for an antiglare layer because it may cause roughness on the plating surface. That is, in order to eliminate the roughness, the plating surface is generally polished after the hard chrome plating. However, as described later, the polishing of the surface after plating is not preferable in the present invention.

  However, it does not deny so-called flash chrome plating, in which, after electroless nickel plating is applied to a metal surface with irregularities, the outermost surface is chrome plated in order to increase the surface hardness. When flash chrome plating is applied, the thickness of the flash chrome plating needs to be thin enough not to impair the shape of the underlying electroless nickel plating, and should preferably be 3 μm or less, more preferably 1 μm or less.

  Further, it is also not preferable to polish the metal plate or roll disclosed in Patent Document 6 after plating. By polishing, a flat portion is generated on the outermost surface, which may cause deterioration of optical characteristics, and because shape control factors increase, it becomes difficult to control the shape with good reproducibility. It is. FIG. 10 is a schematic cross-sectional view of a metal plate in which a flat surface is produced when a surface made by applying electroless nickel plating to an uneven surface obtained by hitting fine particles is polished. Specifically, This corresponds to a state where the surface of the nickel plating layer 74 is polished from the state of FIG. Due to the polishing, some of the surface irregularities 76 of the nickel plating layer 74 formed on the surface of the metal 71 are scraped to produce a flat surface 79.

  As shown in FIG. 9D, using a metal mold having irregularities formed on the surface as shown in FIG. 9C, the irregular shape is transferred to the surface of the film 50, and the antiglare surface is formed. Form. At this time, the shape of the mold can be transferred to the film surface by an arbitrary method. For example, a method in which a thermoplastic resin film is hot-pressed on the uneven surface 76 of the mold and the uneven shape of the mold is transferred to the surface of the thermoplastic resin film, or an ionizing radiation curable resin is applied to the surface of the transparent resin film Then, the ionizing radiation curable resin coating layer is brought into close contact with the uneven surface 76 of the mold in an uncured state, cured by irradiating with ionizing radiation through the film, and the uneven shape 76 of the mold is transferred. it can. After the transfer, as shown in FIG. 9E, the film is peeled from the mold, and the antiglare film 50 is obtained. From the viewpoint of mechanical strength such as prevention of surface scratches, a method using an ionizing radiation curable resin is preferably employed.

  The transparent resin used at this time may be a film having substantially optical transparency. Specific examples include cellulose resins such as triacetyl cellulose, diacetyl cellulose, and cellulose acetate propionate, cycloolefin resins, polycarbonate, polymethyl methacrylate, polysulfone, polyether sulfone, and polyvinyl chloride. . The cycloolefin resin is a resin mainly composed of cyclic olefins such as norbornene and dimethanooctahydronaphthalene, and commercially available products are “Arton” sold by JSR Corporation, and Nippon Zeon Corporation. There are “Zeonoa” and “Zeonex” (both are trade names) on the market.

  Among these, a thermoplastic transparent resin film composed of polymethyl methacrylate, polycarbonate, polysulfone, polyether sulfone, cycloolefin resin, etc. is pressed or pressure-bonded to a mold having an uneven shape at an appropriate temperature, By peeling, it can be used to transfer the uneven shape of the mold surface to the film surface.

  On the other hand, as the ionizing radiation curable resin when transferring the shape using the ionizing radiation curable resin, a compound having one or more acryloyloxy groups in the molecule is preferably used. In order to improve the strength, a trifunctional or higher functional acrylate, that is, a compound having three or more acryloyloxy groups in the molecule is more preferably used. Specific examples include trimethylolpropane triacrylate, trimethylolethane triacrylate, glycerin triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, and the like. Also, an acrylate compound having a urethane bond in the molecule is preferably used in order to impart flexibility to the antiglare surface and make it difficult to break. Specifically, two compounds having at least one hydroxyl group with acryloyloxy group in the molecule, such as trimethylolpropane diacrylate and pentaerythritol triacrylate, are added to diisocyanate compounds such as hexamethylene diisocyanate and tolylene diisocyanate. The urethane acrylate having the above structure is exemplified. In addition, other acrylic resins such as ether acrylates and ester acrylates that initiate radical polymerization by ionizing radiation and cure can also be used.

  Also, cationically polymerizable ionizing radiation curable resins, such as epoxy-based and oxetane-based resins, can be used as the resin in which irregularities are shaped after curing. In this case, for example, a cationically polymerizable polyfunctional oxetane compound such as 1,4-bis [(3-ethyl-3-oxetanylmethoxy) methyl] benzene or bis (3-ethyl-3-oxetanylmethyl) ether, and (4 A mixture with a photocationic initiator such as -methylphenyl) [4- (2-methylpropyl) phenyl] iodonium hexafluorophosphate is used.

  When curing an acrylic ionizing radiation curable resin by irradiation with ultraviolet rays, a radical is generated when irradiated with ultraviolet rays, and an ultraviolet radical initiator is added to start the polymerization / curing reaction. It is done. The ultraviolet irradiation is performed from the glass mold surface side or the transparent resin film surface side, but when the ultraviolet irradiation is performed from the transparent resin film surface side, the radical reaction is performed in the ultraviolet wavelength region where the film can be transmitted. In order to initiate the reaction, an initiator that initiates a radical reaction from the visible region to the ultraviolet region is used.

  Examples of the ultraviolet radical initiator that initiates a radical reaction by ultraviolet irradiation include 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one, 2- In addition to hydroxy-2-methyl-1-phenylpropan-1-one and the like, in particular, when the ultraviolet curable resin is cured by irradiating ultraviolet rays through a transparent resin film containing an ultraviolet absorber, bis (2, 4,6-trimethylbenzoyl) phenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, etc. A phosphorus-based photoradical initiator having absorption in the water is preferably used.

  When the mold having a plated surface with fine irregularities on the surface is flat, the mold irregular surface and a transparent resin film coated with an uncured ionizing radiation curable resin With the uneven surface in close contact with the coating surface, after irradiating the ionizing radiation from the transparent resin film surface side and curing the ionizing radiation curable resin, the base film is peeled off from the mold, and the mold Is transferred to the surface of the transparent film.

  When the mold having a plated surface with fine irregularities on the surface is in a roll shape and the irregular shape of the mold is transferred using an ionizing radiation curable resin, the transparent resin film is uncured ionizing radiation. Ionizing radiation is applied with the surface coated with the curable resin in close contact with the mold roll, and after curing, the entire base film is peeled off from the roll mold to continuously change the shape of the transparent film surface. Can be transferred to.

  The ionizing radiation can be ultraviolet rays or electron beams, but ultraviolet rays are preferably used from the viewpoint of ease of handling and safety. As the ultraviolet light source, a high-pressure mercury lamp, a metal halide lamp, or the like is preferably used, but a metal halide lamp that contains a large amount of visible light components is preferably used particularly when irradiated through a transparent substrate containing an ultraviolet absorber. . In addition, “V-valve” and “D-valve” (both trade names) manufactured by Fusion are also preferably used. The irradiation dose may be a dose sufficient to solidify the UV curable resin until it can be released from the mold, but in order to further improve the surface hardness, irradiation is performed again from the coated surface side after release. May be.

  According to the method as described above, the antiglare layer (antiglare film) obtained can have a haze value of 5% or less. The haze value is specified in JIS K 7136, and is a value represented by (diffuse transmittance / total light transmittance) × 100 (%).

  Thus, when a metal mold having fine irregularities with virtually no flat surface is formed on the surface and the shape is transferred onto the transparent resin film, the antiglare surface of the resulting transparent resin film is also effectively There is no flat surface and fine irregularities are formed.

  The antiglare layer 50 thus obtained is laminated on one side of the polarizer described above with the surface (antiglare surface) subjected to the shaping treatment being the outside, that is, the side not facing the polarizer 30, and the polarizer A transparent protective layer made of, for example, a cellulose acetate-based resin is laminated on the other surface of 30 as necessary to obtain an antiglare polarizing plate 30 having a configuration as shown in FIG. For the lamination, an adhesive having excellent transparency such as a water-based adhesive or an acrylic pressure-sensitive adhesive is advantageously used.

Moreover, in this invention, it was equipped with the polarizer 31 shown as the front side polarizing plate 30 in FIG. 3, and the transparent protective layer 33 provided in the at least one surface, and was provided in one surface of the polarizer. The protective layer 33 has an antiglare layer 50 having fine irregularities formed on the surface, and the thickness direction from the surface of the polarizer 31 on the side where the antiglare layer 50 of the polarizer 31 is not provided to the outermost surface thereof. The phase difference Rth is in the range of −10 nm to +40 nm, and the antiglare layer 50 has a haze of 5% or less with respect to normal incident light, and the width of the dark part and the bright part is 0.5 mm, 1.0 mm and 2.0 mm The total reflection sharpness measured at a light incident angle of 45 ° using three types of optical combs is 50% or less, and the reflectance at a reflection angle of 30 ° for light incident at an incident angle of 30 °. R (30) is 2% or less, and reflectance R (40) at a reflection angle of 40 ° is 0.003% or less. When the reflectance in an arbitrary direction with a reflection angle of 60 ° or more is R (60 or more), the value of R (60 or more) / R (30) is 0.001 or less, and the top of the convex portion of the surface unevenness is the mother. having an average area of a polygon formed when Voronoi dividing the surface as a point is 50 [mu] m ² or more 1,500 ² below the first polarizer, and also shown as a back-side polarizing plate 20, a polarizer 21 and a retardation plate 40, and the thickness direction position of the birefringent layer including the retardation plate 40 existing between the retardation plate 40 side surface of the polarizer 21 and the opposite surface of the retardation plate 40. There is also provided a set of polarizing plates in which the sum of the phase differences Rth is in the range of −40 nm to +40 nm and the sum of the plane phase differences R ₀ is in the range of 100 nm to 300 nm as the second polarizing plate. Since the specific configuration and change thereof are as described above with reference to FIG. 3, redundant description is omitted.

  This set of polarizing plates can be used by being bonded to both the front and back surfaces of the liquid crystal cell. And the adhesive layer 48 is each provided in the outermost surface by which the anti-glare layer 50 of the 1st polarizing plate 30 is not provided, and the retardation plate 40 side outermost surface of the 2nd polarizing plate 20, The liquid crystal cell 10 can be attached to both front and back surfaces.

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

[Example 1]
(A) Production of mold The surface of an aluminum roll (A5056 by JIS) having a diameter of 300 mm was mirror-polished. On the outer surface of the mirror-polished aluminum roll obtained, using a blasting device (obtained from Fuji Seisakusho Co., Ltd.), the zirconia beads “TZ-SX-17” (trade name, average particle diameter) manufactured by Tosoh Corporation 20 μm) was blasted at a blast pressure of 0.1 MPa (gauge pressure, the same shall apply hereinafter) to give irregularities to the surface. The obtained uneven aluminum roll was subjected to electroless bright nickel plating to produce a metal mold. The plating thickness was set to 12 μm, and after plating, the plating thickness was measured using a β-ray film thickness measuring instrument (trade name “Fischer Scope MMS”, obtained from Fisher Instruments Co., Ltd.) and found to be 12.3 μm. It was.

(B) Production of antiglare film A photocurable resin composition “GRANDIC 806T” (trade name) manufactured by Dainippon Ink & Chemicals, Inc. was dissolved in ethyl acetate to obtain a 50% by weight solution. A photopolymerization initiator “Lucirin TPO” (manufactured by BASF, chemical name: 2,4,6-trimethylbenzoyldiphenylphosphine oxide) was added in an amount of 5 parts by weight per 100 parts by weight of the curable resin component, and the coating solution Was prepared. This coating solution was applied onto a 80 μm thick triacetylcellulose (TAC) film so that the coating thickness after drying was 5 μm, and dried for 3 minutes in a drier set at 60 ° C. The dried film was adhered to the concavo-convex surface of the metal mold produced above with a rubber roll so that the photocurable resin composition layer was on the nickel plating layer side. In this state, the photocurable resin composition layer was cured by irradiating light from a high-pressure mercury lamp having an intensity of 20 mW / cm ² from the TAC film side so that the amount of light in terms of h-line was 200 mJ / cm ² . Thereafter, the TAC film was peeled from the mold together with the cured resin to produce a transparent antiglare film comprising a laminate of the cured resin having irregularities on the surface and the TAC film.

   The haze of the anti-glare film was measured using a haze meter “HM-150” manufactured by Murakami Color Research Laboratory Co., Ltd. based on JIS K 7136 and found to be 0.9%. In order to prevent warpage, the sample was subjected to measurement after being bonded to a glass substrate using an optically transparent pressure-sensitive adhesive so that the uneven surface becomes the surface.

  The transmission sharpness was measured using an image clarity measuring device “ICM-1DP” manufactured by Suga Test Instruments Co., Ltd. in accordance with JIS K 7105. In measurement, in order to prevent the sample from warping, it was subjected to measurement after being bonded to a glass substrate using an optically transparent adhesive so that the concavo-convex surface became the surface. In this state, light was incident from the back side of the sample (antiglare film), and measurement was performed. The results were as follows.

Transmission clarity
Optical comb with a width of 0.125 mm: 31.2%
Optical comb with a width of 0.5 mm: 27.9%
1.0 mm wide optical comb: 32.1%
Optical comb with a width of 2.0 mm: 57.0%
Total: 148.2%

  The reflection definition was measured using the same image clarity measuring device “ICM-1DP” as above. In measurement, in order to prevent the sample from warping, it was subjected to measurement after being bonded to a glass substrate using an optically transparent adhesive so that the concavo-convex surface became the surface. In addition, in order to prevent reflection from the back glass surface, a 2 mm thick black acrylic resin plate is adhered to the glass surface of the glass plate on which the antiglare film is pasted, and the sample (antiglare film in this state) is attached. ) Side to measure the light. The results were as follows.

Optical comb with a reflection definition width of 0.125 mm: 3.2% (not included in the total value)
Optical comb with a width of 0.5 mm: 1.5%
Optical comb with a width of 1.0 mm: 5.4%
2.0 mm wide optical comb: 14.8%
Total optical comb value of 0.5 mm or more: 21.7%

  Further, the reflectivity is obtained by irradiating the uneven surface of the antiglare film with parallel light from a He-Ne laser from a direction inclined by 30 ° with respect to the film normal, and in a plane including the film normal and the irradiation direction. Measurement of the change in angle was performed. For the measurement of reflectance, both “3292 03 Optical Power Sensor” and “3292 Optical Power Meter” manufactured by Yokogawa Electric Corporation were used. As a result, R (30) = 0.374%, R (40) = 0.00064%, and R (60) / R (30) = 0.00010.

The surface shape of the antiglare film was measured using a confocal microscope “PLμ2300” manufactured by Sensofar. In measurement, in order to prevent the sample from warping, it was subjected to measurement after being bonded to a glass substrate using an optically transparent pressure-sensitive adhesive so that the uneven surface becomes the surface. The magnification of the objective lens was 50 times. Based on the measurement data, calculation was made based on the above-described algorithm, and the average area of the Voronoi polygon having the top of the convex portion of the surface irregularity as a generating point was 582 μm ² . Further, from the three-dimensional coordinate information, it was confirmed that the entire surface was fine irregularities and no flat portion was present.

  The above-described mold production conditions, optical characteristics, and surface shape (average area of Voronoi polygons) are summarized in Table 2.

  Further, based on the three-dimensional coordinates obtained by the above surface shape measurement, the number of vertices of the convex portion in the region of 200 μm × 200 μm, the arithmetic average height Pa and the maximum sectional height Pt of the sectional curve, and The peak position of the altitude histogram was calculated and the results are shown in Table 3.

(C) Production of anti-glare polarizing plate Anti-glare obtained in (b) on the protective film side of the polarizing plate in which a protective film made of triacetyl cellulose is attached to one side of a polyvinyl alcohol-iodine linear polarizer. The film was bonded so that the concavo-convex surface was on the outside to produce an antiglare polarizing plate.

(D) Production of polarizing film laminate A retardation film having a polycarbonate film thickness-oriented according to the method described in Patent Document 4 and oriented in three dimensions R ₀ = 178 nm and Rth = −34.2 nm is obtained. Produced. This retardation plate is a polarizing plate in which protective films made of triacetyl cellulose are attached to both surfaces of a polyvinyl alcohol-iodine linear polarizer [trade name “Sumikaran SRW842A”, manufactured by Sumitomo Chemical Co., Ltd., one-side protective film Of Rth = 55 nm, R ₀ = 1 nm] via an adhesive to prepare a polarizing film laminate. At this time, it arrange | positioned so that the slow axis of a phase difference plate and the absorption axis of a polarizing plate may orthogonally cross.

(E) Production and Evaluation of Liquid Crystal Display Device The polarizing plates on both the front and back surfaces were peeled off from a commercially available television (“W32L-H9000” manufactured by Hitachi, Ltd.) on which an IPS mode liquid crystal display element was mounted. Instead of these original polarizing plates, on the front side, the anti-glare polarizing plate produced in the above (c), the anti-glare layer so that the absorption axis of the polarizing plate coincides with the absorption axis direction of the original polarizing plate. The polarizing film laminate produced in (d) above is pasted on the back side with an adhesive, so that the absorption axis coincides with the absorption axis direction of the original polarizing plate. It bonded through the adhesive on the phase difference plate side. Thus, a liquid crystal display device with an antiglare layer was produced.

  Table 1 summarizes the retardation values of the front-side polarizing plate and the rear-side polarizing film laminate in this liquid crystal display device.

  The backlight of this liquid crystal display was turned on, and the contrast change due to the viewing angle was measured with a liquid crystal viewing angle / chromaticity characteristic measuring device “EZ Contrast” manufactured by ELDIM, and the equal contrast curve is shown in FIG. In this isocontrast curve, the right direction of the screen is 0 degree, the counterclockwise direction is positive, and the azimuth angle is displayed (numbers are displayed every 45 degrees from 0 degree to 315 degrees), and the horizontal axis is “10”, “20”..., “80” means an inclination angle from the normal line at each azimuth angle. For example, the right end of the circle means the contrast in the direction in which the azimuth angle is 0 degrees (right side of the screen) and is tilted nearly 90 degrees from the normal, and the center of the circle means the contrast in the normal direction of the screen. “CR = 100” is displayed on the curve with the contrast of 100, and “CR = 200” is displayed on the curve with the contrast of 200. Contrast 300 and 400 and an iso-contrast curve in which the contrast increases by 100. The contrast in the front direction is about 700. Here, the contrast is the ratio of the luminance at the time of white display (voltage application to the liquid crystal cell) to the luminance at the time of black display (no voltage application to the liquid crystal cell).

  From the visual observation and the isocontrast curve of FIG. 11, it was found that this liquid crystal display device has a small change in luminance due to the viewing angle and a small viewing angle dependency.

  The backlight of this liquid crystal display device is turned on in the dark room, and the brightness of the liquid crystal display device in the black display state and the white display state is measured by using a luminance meter “BM5A” manufactured by Topcon Co., Ltd. Calculated. Here, the contrast is represented by the ratio of the luminance in the white display state to the luminance in the black display state. As a result, the contrast in the dark room was 697. Next, this evaluation system was moved into a bright room, and the reflection state was visually observed as a black display state. As a result, almost no reflection was observed, and it was confirmed that this liquid crystal display device had a good antiglare property. In addition, the surface texture in the bright room and the whitishness were implied. The evaluation results are summarized in Table 4.

[Example 2]
In the said Example 1, as a front side polarizing plate, the glare-proof film produced by the method similar to (b) of Example 1 on the surface at the side of visual recognition of a polyvinyl alcohol-iodine type | system | group linear polarizer is directly used as a protective film. Even if a similar liquid crystal display device is produced using a polarizing plate bonded so that the uneven surface is on the outside, the same result as in Example 1 is obtained.

[Examples 3 and 4]
The plating thickness was changed as shown in Table 2, and a metal mold having irregularities on the surface was prepared in the same manner as in Example 1 (a). Using each mold, a transparent antiglare film made of a laminate of a cured resin having irregularities on the surface and a TAC film was produced in the same manner as in (b) of Example 1. Table 2 shows the optical characteristics and surface shape (average area of Voronoi polygons) of the obtained antiglare film. For each film, the number of convex vertices, the arithmetic average height Pa and the maximum cross-sectional height Pt of the cross-sectional curve, and the peak position of the altitude histogram were determined in the same manner as in Example 1, and the results are shown in Table 3. It was. Further, using these films, a liquid crystal display device with an antiglare layer was produced in the same manner as in (c) to (e) of Example 1, the contrast and antiglare properties were evaluated, and the results are shown in Table 4. .

[Comparative Examples 1-5]
Anti-glare films “AG1”, “AG3”, “AG5”, “AG5”, which are used in the anti-glare film of the polarizing plate “Sumikaran” sold by Sumitomo Chemical Co., Ltd. With respect to AG6 "and" AG8 "(referred to as Comparative Examples 1 to 5 respectively), the respective optical characteristics and the average area of the Voronoi polygons having the convex vertices of the surface irregularities as the generating points are shown in Examples 1 and 3. The results are shown in Table 2 together with the results of 4 and 4. For these films, based on the three-dimensional coordinates obtained when calculating the average area of the Voronoi polygon, the number of vertices of the convex portion, the arithmetic average height Pa of the cross-sectional curve, and the maximum cross-sectional height Pt In addition, the peak position of the altitude histogram was calculated in the same manner as in Example 1, and the results are shown in Table 3 together with the results of Examples 1, 3, and 4. Further, using these antiglare films, a liquid crystal display device with an antiglare layer was produced in the same manner as in Example 1, and the contrast and antiglare properties were evaluated. The results were the results of Examples 1, 3, and 4. The results are also shown in Table 4.

  As shown in Table 2 and Table 4, the samples of Examples 1, 3, and 4 in which the haze, reflection profile, and surface shape satisfy the provisions of the present invention exhibit excellent antiglare properties (no reflection), The contrast was high and the visibility was excellent. In addition, good results were shown in terms of surface texture and whitening prevention.

On the other hand, in Comparative Examples 1 and 2, R (30) is 2% or less, R (40) is 0.003% or less, and R (60) / R (30) is 0.001 or less. Therefore, no whitening was seen. However, since the average area of the Voronoi polygon exceeded 1,500 μm ² , the texture was poor and the antiglare property was insufficient. In Comparative Examples 3 to 5, since R (60) / R (30) exceeded 0.001, whitening was observed. Moreover, all the Comparative Examples 1-5 had a contrast lower than the anti-glare film of this invention irrespective of the haze.

It is a cross-sectional schematic diagram which shows the structural example of the liquid crystal display device of an IPS mode. In order to explain the principle of the IPS mode, it is a schematic perspective view showing an example of normally black, in which (A) shows a voltage non-application state and (B) shows a voltage application state. It is a cross-sectional schematic diagram which shows the example of the liquid crystal display device which concerns on this invention. It is a schematic perspective view which shows the preferable axial relationship of the apparatus shown in FIG. It is a schematic perspective view which shows the incident direction and reflection direction of the light with respect to a glare-proof layer. It is an example of the graph which plotted the reflection angle and reflectance (a reflectance is a logarithmic scale) of the reflected light with respect to the light which injected at an angle of 30 degrees from the normal line of the glare-proof layer. It is the perspective view which showed typically the algorithm of the convex part determination of an glare-proof layer. It is a Voronoi figure which shows an example when performing Voronoi division | segmentation by using the convex-part vertex of an anti-glare layer as a mother point. It is a cross-sectional schematic diagram which shows a preferable method for manufacturing an anti-glare layer for every process. It is a cross-sectional schematic diagram which shows the state which polished the surface after electroless nickel plating. 6 is a diagram showing isocontrast curves of the liquid crystal display device manufactured in Example 1. FIG.

Explanation of symbols

10 ... Liquid crystal cell,
11, 13 ... cell substrate,
12 …… Electrodes on the substrate
14 ... Liquid crystal layer,
15 …… Liquid crystal molecules,
16: Linearly polarized light incident on the liquid crystal cell,
17a: linearly polarized light emitted from the liquid crystal cell when no voltage is applied,
17b: elliptically polarized light emitted from the liquid crystal cell when a voltage is applied,
18 ... Electric field,
19 …… Slow axis (molecular long axis) of liquid crystal layer when no voltage is applied,
20 …… Back side polarizing plate,
21 …… Back side polarizer,
22, 23 ... Transparent protective layer of the back side polarizing plate,
25 …… The transmission axis of the back side polarizing plate,
26 …… Absorption axis of back side polarizing plate,
30 …… Front-side polarizing plate,
31 …… Front polarizer
32, 33 ... Transparent protective layer for the front-side polarizing plate,
35 …… Transmission axis of the front polarizing plate,
36 …… Absorption axis of front polarizing plate,
40 ... retardation plate,
46 …… Slow axis of retardation plate,
48 …… Adhesive layer,
50 ... Anti-glare layer (anti-glare film),
51 …… Transparent film substrate,
52 …… Ionizing radiation curable resin or its cured product,
55 …… Film normal,
56 ... Incident light direction,
57 …… Specular reflection direction,
58 …… Any reflection direction,
59 …… A plane including the incident ray direction and the film normal,
θ ...... reflection angle,
61 …… Any point on the antiglare film,
62 …… Anti-glare film surface,
63 …… Film reference plane,
64 …… A projected circle of a circle centered on an arbitrary point on the antiglare film on the film reference plane,
65 …… Projection point of convex part vertex (voron point of Voronoi division),
66 …… Voronoi polygon,
67 …… Voronoi polygon that touches the measurement field boundary not counted
71 …… Metal substrate,
72: Polished surface,
73 ...... concave surface formed by hitting fine particles,
74 ... Nickel plating layer,
76 .. Uneven surface remaining after plating,
79. Flat surface generated when the surface after plating is polished,
80 …… Backlight.

Claims (4)

Liquid crystal is sealed between a pair of cell substrates parallel to each other, and the liquid crystal is aligned in parallel and substantially in the same direction, and a front-side polarizing plate disposed on the viewing side of the liquid crystal cell And a back-side polarizing plate disposed on the opposite side, and the direction of the molecular major axis of the liquid crystal changes in a plane parallel to the substrate by a change in voltage applied to the liquid crystal cell so that display is performed. A liquid crystal display device comprising:
At least one retardation plate is disposed between the back-side polarizing plate and the liquid crystal cell, and is present between the liquid crystal cell-side surface of the polarizer constituting the back-side polarizing plate and the back-side substrate surface of the liquid crystal cell. The sum of the thickness direction retardation Rth of the birefringent layer including the retardation plate is in the range of −40 nm to +40 nm, and the sum of the planar retardation R ₀ is in the range of 100 nm to 300 nm.
The front-side polarizing plate includes a polarizer and a viewing-side transparent protective layer provided on the opposite side of the surface facing the liquid crystal cell, and does not have a transparent protective layer on the liquid crystal cell-side surface of the polarizer. The child is directly bonded to the front substrate surface of the liquid crystal cell, and
The viewing-side transparent protective layer has fine irregularities formed on the surface, has a haze of 0.4% or more and 2.3% or less with respect to normal incident light, and has a dark portion and a bright portion width of 0.5 mm, 1 The total reflection sharpness measured at an incident angle of 45 ° using three types of optical combs of 0.0 mm and 2.0 mm is less than 50%. For light incident at an incident angle of 30 °, The reflectivity R (30) at a reflection angle of 30 ° is 2% or less, the reflectivity R (40) at a reflection angle of 40 ° is 0.003% or less, and the reflectivity in an arbitrary direction with a reflection angle of 60 ° or more is R ( 60 or more), the polygon formed when the value of R (60 or more) / R (30) is 0.001 or less and the surface is Voronoi divided with the vertex of the convex portion of the surface irregularity as a base point Having an antiglare layer having an average area of 372 μm ² or more and 582 μm ² or less LCD device.   The antiglare layer is formed by bumping fine particles having an average particle diameter of 10 to 35 μm on the polished metal surface to form a mold by electroless nickel plating on the bumpy surface of the metal. The liquid crystal display device according to claim 1, comprising a resin film having fine irregularities obtained by transferring the irregular surface to a transparent resin film and then peeling the transparent resin film having the irregular surface transferred from the mold.   The transparent resin film is obtained by applying an ultraviolet curable resin to the surface of a transparent film substrate, and the unevenness of the mold is transferred to the surface of the ultraviolet curable resin and cured. Liquid crystal display device. The liquid crystal display device according to claim 2, wherein the transparent resin film is made of a transparent thermoplastic resin, and unevenness of the mold is transferred to the surface thereof .