JP2013077601A - Display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical film with which a high electromagnetic wave shield property and a lightness contrast improving function can be made compatible and a wide angle of view can be secured.SOLUTION: An optical film comprises a transparent substrate layer 1 and a double-function linear part 2 which is provided in the transparent substrate layer so as to form a grid within the plane thereof. A plurality of horizontal linear portions 2a and vertical linear portions 2b forming the grid of the double-function linear parts 2 are disposed in parallel at fixed intervals, respectively. The double-function linear part has a laminate structure including a light absorption layer 4 and a conductive layer 5 and has a trapezoidal or triangular cross-sectional shape in which the side of the light absorption layer is thinner than the side of the conductive layer, and the vertical linear portions are lower than the horizontal linear portions.

Description

  The present invention relates to an optical film attached to a display device such as a plasma display.

  2. Description of the Related Art In recent years, display devices for monitors, television applications and the like have become thinner and larger, and a plasma display is known as one type. In a plasma display, a high level electromagnetic wave is generated from the panel. The electromagnetic wave is provided with a regulation value from the viewpoint of the operation of the electronic device and the safety to the human body, and it is essential to suppress the electromagnetic wave from the plasma display below this regulation value. Therefore, a filter for shielding this electromagnetic wave is provided on the observer side of the plasma display panel.

  As such an electromagnetic wave shielding filter, there are two types, a type in which metal is sputtered in multiple layers and a type in which metal is arranged in a mesh pattern. Among these, with respect to electromagnetic wave shielding performance, the mesh pattern type is excellent, and it can be applied to various types of plasma displays from conventional high-definition image quality panels to high-definition panels such as full high-definition image quality. However, on the other hand, the type of mesh pattern is poor in cost advantage. Therefore, in addition to a method of forming a mesh pattern by etching a metal foil, studies for reducing manufacturing costs such as a printing method have been performed.

  In addition, since the plasma display has a higher light reflectance on the panel surface than the liquid crystal display, a decrease in bright place contrast due to reflection of light from ceiling illumination has been regarded as a problem. In order to solve this problem, a film called a louver film having a structure in which linear light absorbing portions arranged continuously at a constant interval are covered with a transparent base material layer is used. The louver film is arranged in a horizontal direction when viewed from the display observer, that is, in a direction parallel to the ground, and is mounted on the observer side of the panel, and is removed by the side wall of each linear light absorber. By absorbing the light, the bright place contrast can be improved.

  However, since a new louver film is added, an increase in cost is inevitable. Furthermore, when combined with a mesh pattern type electromagnetic wave shielding film having high electromagnetic wave shielding performance, the cost advantage is further reduced. At the same time, since two types of substrates having a pattern structure are overlapped, a slight moiré is caused by a slight misalignment, resulting in a decrease in yield.

  As a method for avoiding such an increase in cost, there has been proposed a method for simultaneously improving electromagnetic wave shielding performance and bright place contrast by configuring the linear light absorbing portion to have conductivity (Patent Document 1). ).

  Furthermore, in order to obtain sufficient conductivity, not only a linear light absorbing portion extending in the horizontal direction with respect to the ground (hereinafter referred to as a horizontal linear portion) but also a linear light absorbing extending in the vertical direction. It is necessary to arrange a portion (hereinafter referred to as a vertical linear portion). In other words, the horizontal linear portions and the vertical linear portions are arranged in a grid and are electrically connected to each other, thereby increasing the conductivity of the entire film surface. However, this vertical linear portion causes a problem that the viewing angle is narrowed. For this problem, a method has been proposed in which the vertical linear portion pitch is set to be several times the horizontal linear portion pitch (Patent Document 2).

JP 2006-253332 A JP 2008-242232 A

  However, in the case of a configuration in which the linear light absorbing portion having conductivity disclosed in Patent Document 1 is arranged to obtain the electromagnetic wave shielding performance and the performance of improving the bright place contrast at the same time, in either the bright place contrast or the electromagnetic wave shielding, However, it is difficult to obtain sufficient performance.

  The problem is that, as a material constituting each linear light absorbing portion, (1) black conductive particles, that is, conductive particles that have been subjected to surface blackening treatment, or (2) conductive particles to which a black dye or pigment is added, Due to the need for either. In either case, increasing blackening in order to improve external light absorption performance decreases the conductivity. In other words, in the case of (1), the contact resistance between particles increases as the surface blackening process proceeds, and in the case of (2), the concentration of conductive particles decreases as the concentration of black dye or pigment increases. This is because the macro resistance increases. As a result, it is difficult to achieve both bright place contrast improvement performance and electromagnetic wave shielding performance.

  Also, the method disclosed in Patent Document 2 that solves the problem of narrowing the viewing angle due to the arrangement of the vertical linear portions by setting the vertical linear portion pitch to be several times the horizontal linear portion pitch is adopted. In this case, since the electrical connection points decrease as the vertical linear portion pitch for connection increases, the electromagnetic wave shielding performance is inevitably deteriorated. For this reason, it has been difficult to achieve both sufficient electromagnetic shielding performance and a sufficient viewing angle.

  The present invention has been made in view of the above-described problems of the prior art, and aims to provide a display device including an optical film that achieves both high electromagnetic shielding properties and a bright contrast enhancement function and can ensure a wide viewing angle. To do.

  In order to solve the above problems, a display device of the present invention includes a display panel that displays an optical image, and a front filter disposed on a front surface of the display panel, the front filter including a transparent base material layer, In the transparent base material layer, it is comprised using the optical film provided with the bifunctional linear part provided so that a grating | lattice might be formed in the surface, and the said bifunctional linear part is a light absorption layer and electroconductivity. A plurality of horizontal lines having a trapezoidal or triangular cross-sectional shape in which the light absorption layer side is narrower than the conductive layer side, and forming a lattice of the bifunctional linear portion. The vertical portions and the vertical linear portions are arranged in parallel at regular intervals, and the vertical linear portions are lower in height than the horizontal linear portions.

  The method for producing an optical film of the present invention includes a first step of forming grooves corresponding to the horizontal linear portions and vertical linear portions in the transparent base material layer, and light absorption in the grooves of the transparent base material layer. A second step of forming the light absorbing layer made of the light absorbing material and the binder resin at the bottom of the groove by filling a liquid composition containing a material and a binder resin and a solvent and drying the solvent; And a third step of forming the conductive layer by filling a liquid composition containing a conductive material into the groove of the transparent base material layer on which the light absorption layer is formed.

  The present invention takes a form in which the light absorption layer and the conductive layer are separately formed in the horizontal linear portion and the vertical linear portion, thereby ensuring an optimum condition for each function while avoiding an increase in cost. Both light absorption performance and high electromagnetic shielding performance can be achieved. Further, by reducing the height of the vertical linear portion, it is not necessary to make the pitch of the vertical linear portion sparse in order to secure the viewing angle, so that both a wide viewing angle and high electromagnetic shielding performance can be achieved. .

  Further, according to the manufacturing method of the present invention, the film can be easily manufactured by adopting the step of sequentially forming the light absorption layer and the conductive layer in the grooves corresponding to the horizontal linear portion and the vertical linear portion. Is possible.

Top view of the optical film in the first embodiment An enlarged cross-sectional view of the optical film taken along line YY in FIG. Expanded sectional view along line XX in FIG. 1 of the optical film Sectional drawing which shows the form in which the optical film was formed on the transparent support base material Sectional drawing which shows 1 process of the manufacturing method of the same optical film Sectional drawing which shows the process following FIG. 5A of the manufacturing method Sectional drawing which shows the process following FIG. 5B of the manufacturing method Sectional drawing which shows the structure of the front filter for display apparatuses using the optical film in Embodiment 2. Sectional drawing which shows the structure of the display apparatus provided with the optical film in Embodiment 3.

  The optical film of the present invention can take the following aspects based on the above configuration.

  That is, it is preferable that the height of the vertical linear portion is set in a range of 1/10 to 1/2 with respect to the height of the horizontal linear portion.

  Further, a frame-shaped outer peripheral electrode portion is disposed around a region where the bifunctional linear portion is formed, and the outer peripheral electrode portion has a laminated structure including the light absorption layer and the conductive layer, and the bifunctional The conductive layer of the linear part is preferably connected to the conductive layer of the outer peripheral electrode part.

  The display device of the present invention includes a display panel that displays an optical image, and a front filter disposed in front of the display panel, and the front filter is configured using the optical film having any one of the above-described configurations, The upper base side of the trapezoidal cross-sectional shape or the apex side of the triangular cross-sectional shape is mounted in the direction in which the optical image is displayed. Thereby, the electromagnetic wave radiated | emitted with respect to the observer side is shielded, and also a bright field contrast is high and a wide viewing angle is ensured.

  Embodiments of the present invention will be described with reference to the drawings. In addition, this invention is not limited to the structure as described in drawing.

<Embodiment 1>
1 is a top view of the optical film in Embodiment 1, FIG. 2 is an enlarged sectional view taken along line YY in FIG. 1, and FIG. 3 is an enlarged sectional view taken along line XX in FIG. Indicates. This optical film is attached to the surface on which the image of the display device is displayed. Therefore, FIG. 1 shows the configuration of the display device as viewed from the viewer side.

  As shown in FIG. 1, this optical film has a configuration in which a bifunctional linear portion 2 is provided in a transparent base material layer 1 so as to form a lattice in the plane. The lattice of the bifunctional linear portion 2 is formed by a plurality of horizontal linear portions 2a and vertical linear portions 2b. An outer peripheral electrode portion 3 is disposed around the bifunctional linear portion 2.

  As shown in FIGS. 2 and 3, the horizontal linear portion 2 a and the vertical linear portion 2 b are formed in a trapezoidal cross-sectional shape in which the light absorption layer 4 and the conductive layer 5 are stacked. The outer peripheral electrode portion 3 also has a form in which the light absorption layer 4 and the conductive layer 5 are laminated. The conductive layer 5 of the horizontal linear portion 2a and the conductive layer 5 of the vertical linear portion 2b are connected to each other at the intersection. Further, the conductive layer 5 of the horizontal linear portion 2 a and the vertical linear portion 2 b is connected to the conductive layer 5 of the outer peripheral electrode portion 3.

  The horizontal linear portion 2a and the vertical linear portion 2b are arranged in parallel at regular intervals in the horizontal direction and the vertical direction, as shown in the planar shape of FIG. Further, as shown in FIGS. 2 and 3, the height of the vertical linear portion 2b is lower than the height of the horizontal linear portion 2a.

  The above forms of the horizontal linear portion 2a and the vertical linear portion 2b are the basic configuration of the optical film of the present invention. This optical film is attached to the display device with the light absorbing layer 4 side facing the viewer side of the display device, that is, in the direction in which the optical image is displayed. In this configuration, since the light absorption layer 4 and the conductive layer 5 are individually formed in the linear portions of the horizontal linear portion 2a and the vertical linear portion 2b, optimum conditions are satisfied for each layer. It is possible to achieve both high contrast and high electromagnetic shielding performance. Further, since the vertical linear portion 2b is lowered, it is not necessary to make the pitch of the vertical linear portions 2b sparse in order to secure the viewing angle, so that both a wide viewing angle and high electromagnetic shielding performance can be achieved.

  In addition, in the said structure, the transparent base material layer 1 in which the light absorption layer 4 and the conductive layer 5 are provided is the form used independently as a base material. On the other hand, as shown in FIG. 4, the transparent substrate layer 1 may be supported by a transparent support substrate 6 made of glass or a resin film.

  The cross-sectional shapes of the horizontal linear portion 2a and the vertical linear portion 2b formed by laminating the light absorbing layer 4 and the conductive layer 5 are not limited to the trapezoid as shown, but may be a square or a triangle. The vertex may be a curve.

  The region where the horizontal linear portion 2a and the vertical linear portion 2b are formed is set so as to cover the entire image display area of the display device on which the optical film is mounted. The line widths of the horizontal linear portion 2a and the vertical linear portion 2b are not particularly limited, but it is desirable that the line width is narrow in consideration of the light transmittance from the display device. Practically, it is preferably 50 μm or less, more preferably about 20 μm. In this range, the horizontal linear portions 2a and the vertical linear portions 2b may have different line widths.

  Below, the function of the horizontal linear part 2a and a desirable structure are demonstrated in detail. The horizontal linear portion 2a is provided for the purpose of improving a bright place contrast by absorbing external light and imparting conductivity.

  First, the role for improving the contrast in a bright place will be described. Ceiling illumination is the main external light source incident on the surface of the display device. Most of the outside light is incident obliquely from above the display device. Therefore, when the light absorbing material is arranged in the horizontal direction when viewed from the observer, external light is absorbed by the side wall of the line, reflection from the display device is suppressed, and the bright place contrast is improved.

  Considering the action of the light absorbing material, the larger the side wall area of the light absorbing layer 4 of the horizontal linear portion 2a, the greater the effect for improving the bright place contrast. Therefore, the higher the light absorbing layer 4 is, the better. However, if the height of the light absorption layer 4 of the horizontal linear portion 2a is too high, a change in luminance when the viewpoint of the observer of the display device moves up and down with respect to the ground becomes undesirably large. On the other hand, if the height of the light absorption layer 4 of the horizontal linear portion 2a is too low, the light absorption performance is inferior.

  Therefore, the aspect ratio of the horizontal linear portion 2a is preferably in the range of 1: 1 to 1: 5 when the line width is 1. Furthermore, the height of the light absorption layer 4 of the horizontal linear portion 2a is desirably 1/2 or more of the height of the horizontal linear portion 2a. Here, “horizontal” is not meant to be limited to a strictly horizontal direction, but is used to allow an angle range of about ± 30 degrees around an axis parallel to the ground. It is done. This is because a sufficient practical effect can be obtained.

  Next, the role of the horizontal linear portion 2a in imparting conductivity will be described. In the present invention, the conductivity that determines the electromagnetic wave shielding property is not limited. However, if the height of the conductive layer 5 is too high, the side wall area of the light absorption layer 4 is reduced, and the effect of improving the bright place contrast cannot be sufficiently obtained. It is desirable to set the height to be less than ½ with respect to the height of the horizontal linear portion 2a.

  Next, the function and desirable configuration of the vertical linear portion 2b will be described in detail. The vertical linear portion 2b is provided to electrically connect the horizontal linear portions 2a to each other and improve electromagnetic wave shielding performance. However, if the surface reflects light, the display device is inferior in contrast as white as a whole. Therefore, the light absorption layer 4 needs to be provided near the top of the vertical linear portion 2b. Further, in the present invention, the conductivity that determines the electromagnetic wave shielding property is not limited, and therefore the height of the conductive layer 5 in the vertical linear portion 2b with the upper limit being a ratio at which no intermittent portion is generated in the light absorption layer 4. Can be adjusted.

  As in the present embodiment, by arranging the conductive vertical linear portion 2b so as to intersect the horizontal linear portion 2a, high electromagnetic wave shielding performance is exhibited. Here, “vertical” does not mean that it is limited to a strictly vertical direction, but is used to allow an angle range of about ± 30 degrees around an axis perpendicular to the ground. It is done. This is because a sufficient practical effect can be obtained.

  The height of the vertical linear portion 2b is set in consideration of the following points. That is, if the height of the vertical linear portion 2b is the same as that of the horizontal linear portion 2a for which external light absorption is intended, the left and right viewing angles are narrowed. In order to avoid this, if the pitch of the vertical linear portions 2b is made sparse with respect to the pitch of the horizontal linear portions 2a, the number of electrical connection points decreases, and it becomes difficult to achieve both electromagnetic shielding performance and a viewing angle. .

  Therefore, from this viewpoint, the height of the vertical linear portion 2b needs to be lower than the height of the horizontal linear portion 2a. Thereby, it is not particularly necessary to make the pitch of the vertical linear portions 2b sparse in order to secure a viewing angle, and many electrical contacts can be maintained, so that both a wide viewing angle and high electromagnetic shielding performance can be achieved. As described above, the height of the vertical linear portion 2b is preferably lower from the viewpoint of securing the viewing angle, but from the viewpoint of ensuring conductivity, 1/10 to 1 of the height of the horizontal linear portion 2a is considered. A range of / 2 is desirable.

  The outer peripheral electrode portion 3 is provided as a contact for electrically connecting the conductive layer 5 in the horizontal linear portion 2a and the vertical linear portion 2b to the display device and grounding. This is because the electromagnetic wave absorbed in the conductive layer 5 generates a new charge, and this charge becomes a new electromagnetic wave generation source, so that it is necessary to quickly release the generated charge to the outside. However, the structure for grounding the conductive layer 5 is not limited to the outer peripheral electrode portion 3, and any other structure may be adopted.

  As shown in the drawing, it is desirable that the surface of the outer peripheral electrode portion 3 is covered with the light absorption layer 4. Thereby, it can be used as it is as a black frame of the display device. For this reason, the width of the outer peripheral electrode portion 3 is preferably less than the frame width of the display device or, if it also serves as the frame of the display device, the width of the frame of the display device. The thickness of the outer peripheral electrode portion 3 is not particularly limited for the purpose of the present invention.

  The transparent base material layer 1 is colorless and transparent, and is not limited. However, it is more desirable that the refractive index of the transparent base material layer 1 is higher than that of at least one of the light absorption layer 4 or the conductive layer 5. This is because the panel light is totally absorbed in the side wall in contact with at least one of the light absorption layer 4 and the conductive layer 5 without being absorbed by the light absorption layer 4 according to Snell's equation.

  Next, an example of the manufacturing method of the optical film in this Embodiment is demonstrated with reference to FIG. 5A-FIG. 5C. First, as shown in FIG. 5A, a transparent material layer 1a is formed on a transparent support substrate 6, and horizontal grooves 7, vertical grooves 8 (shown by broken lines), and an outer peripheral groove 9 are formed in the transparent material layer 1a. Thereby, the transparent base material layer 1 is created.

  Next, as shown in FIG. 5B, in the horizontal groove 7, the vertical groove 8, and the outer peripheral groove 9, a liquid composition containing a light-absorbing material, a binder resin, and a solvent is placed on the opening side (upper part in the drawing) of each groove. Fill so that the unfilled part remains. By drying the solvent of the liquid composition, a light absorbing layer 4 made of a light absorbing material and a binder resin is formed on the bottom side of each groove, and a part of the space remains on the opening side of each groove.

  Next, as shown in FIG. 5C, in the upper space of the light absorption layer 4 formed in the horizontal groove 7, the vertical groove 8, and the outer peripheral groove 9, a liquid composition containing a conductive material is filled to form the conductive layer 5. To do. Thereby, the horizontal linear part 2a, the vertical linear part 2b, and the outer periphery electrode part 3 are formed, and the optical film shown in FIG. 4 is completed.

  The method of forming the transparent base material layer 1 by forming the horizontal grooves 8, the vertical grooves 9, and the outer peripheral grooves 10 in the transparent material layer 1a provided on the transparent support base material 6 is particularly limited in the present embodiment. However, for example, the following method can be used.

  (1) An energy curable resin film is formed as the transparent material layer 1a on the transparent support substrate 6, and grooves are formed on the energy curable resin film by photolithography to form the transparent substrate layer 1.

  (2) An energy curable resin film is formed on the transparent support substrate 6 as the transparent material layer 1a, and a mold having an inverted groove shape is pressed against the energy curable resin film at a certain distance and cured. Then, a groove is formed to form the transparent substrate layer 1 (hereinafter referred to as a transfer method).

  From the viewpoint of the equipment cost and the time required for formation, formation by a transfer method is preferable, and in particular, when a roll-shaped mold is used as the above-described mold, continuous processing becomes possible, which is further preferable.

  As the transparent support base 6, a general resin film, that is, polyethylene terephthalate (PET), polyethylene (PE), polyethylene naphthalate (PEN), polyphenylene sulfide (PPS), polyamide (PA), polyimide (PI), etc. Can be used. The surface may be subjected to an easy adhesion treatment or the like. Moreover, the thickness of the transparent support substrate 6 is not particularly limited, but is preferably 150 μm to 250 μm.

  In addition, the transparent support base material 6 can also peel, after forming a groove | channel in the transparent base material layer 1. FIG. In this case, the transparent support substrate 6 does not need to be transparent.

  Moreover, as energy curable resin for forming the transparent base material layer 1, ultraviolet curable resin, electron beam curable resin, thermosetting resin, etc. can be used. Among these, the ultraviolet curable resin is preferable because it can be formed with simple equipment and in a short time. As the ultraviolet curable resin, acrylate-based, methacrylate-based, epoxy-based, vinyl-based monomers or oligomers, or a mixture of monomers and oligomers that are cured by applying energy can be used.

  Further, as described above, the refractive index of the transparent base material layer 1 is not limited, but is preferably larger than the refractive index of the light absorption layer 4. For this reason, you may make a high refractive index by disperse | distributing a filler to the transparent base material layer 1. FIG. As a material for such a filler, titanium oxide, zirconium oxide, niobium oxide, zinc sulfide, or the like can be used.

  As a method of forming the light absorption layer 4 in the groove of the transparent base material layer 1, the groove is filled with a liquid composition containing a light absorbing material, a binder resin and a solvent with a blade or the like, and the solvent is dried. A method of forming the light absorption layer 4 made of a light absorption material and a binder resin on the bottom is suitable. Although there is no restriction | limiting in particular in the material used for this method, As a light absorption material, a carbon particle, the metal or metal oxide by which the surface was blackened, etc. can be used. As the binder resin, for example, cellulose resins such as ethyl cellulose and carboxymethyl cellulose, acrylic resins, vinyl resins, and the like can be used.

  Further, as described above, the refractive index of the light absorbing layer 4 is not limited, but is preferably smaller than the refractive index of the transparent substrate layer 1. Since the refractive index of the light absorption layer 4 is determined by the binder resin, in order to set the light absorption layer 4 to a refractive index lower than that of the transparent substrate layer 1, it is necessary to use a binder resin having a low refractive index. desirable. As the binder resin having a low refractive index, for example, a fluorine-based resin such as polytrifluoroethylene chloride, polytetrafluoroethylene, tetrafluoroethylene, hexafluoroethylene copolymer resin, silicon resin, or the like can be used.

  Moreover, as a binder resin, the liquid energy curable resin described in the formation method of the below-mentioned conductive layer 5 can also be used. That is, after drying the solvent, it can be made to function as a binder resin by irradiating energy and curing. Examples of the ultraviolet curable resin, which is an example of the energy curable resin, include those that impart energy to a monomer or oligomer such as an acrylate, methacrylate, epoxy, or vinyl, or a mixture of the monomer and the oligomer to be cured. Can do. When the light absorption layer 4 is set to a refractive index lower than that of the transparent base layer 1, for example, a urethane acrylate resin can be used as an ultraviolet curable resin having a low refractive index.

  In the present embodiment, as described above, the light absorption layer 4 needs to be present in the vicinity of the top of the vertical linear portion 2b. For this purpose, as shown in FIG. 5B, the height of the light absorption layer 4 formed by filling and drying the liquid composition in the horizontal groove 7, the vertical groove 8, and the outer peripheral groove 9 is a vertical linear shape. It is necessary to set the solvent ratio in the liquid composition so as to exceed the depth of the vertical groove 8 for the portion 2b. As a result, the light absorption layer 4 can always be formed in the vicinity of the top of the horizontal linear portion 2a as well as the vertical linear portion 2b.

  As a method of forming the conductive layer 5 in the groove of the transparent substrate layer 1 on which the light absorption layer 4 is formed, a method of forming the liquid composition containing a conductive material by filling the groove with a blade or the like is preferable. It is. As this liquid composition, (1) a solventless type, that is, a liquid composition comprising a conductive material and a liquid energy curable resin, and (2) a solvent type, that is, a liquid composition comprising a conductive material, a solvent and a binder resin, There are two types.

  When the solventless liquid composition (1) is used, the liquid composition is bladed in the unfilled portions of the grooves 7, 8, 9 of the transparent substrate layer 1 on which the light absorption layer 4 is formed. After filling with, etc., energy is applied and cured. When the solvent-type liquid composition (2) is used, the liquid composition is applied to the unfilled portions of the grooves 7, 8, and 9 of the transparent base material layer 1 on which the light absorption layer 4 is formed. Then, after the solvent is dried, the conductive layer 5 is formed again by repeatedly filling and drying the solvent-type liquid composition by the same method. Alternatively, a method in which the conductive layer 5 is formed by filling and drying the solvent-type liquid composition and then filling and curing the solvent-free liquid composition can be employed.

  The conductive material that satisfies the conditions for applying the method for forming the conductive layer 5 may include pigments or dyes in addition to conductive particles such as silver, copper, iron, aluminum, nickel, and chromium. Although it is good, only the conductive particles are desirable because high conductivity can be obtained.

  Examples of the solventless liquid energy curable resin (1) include ultraviolet curable, electron beam curable, and thermosetting resins. Among these, the ultraviolet curable resin is a simple facility and can be used in a short time. Since it can form, it is preferable. Examples of such ultraviolet curable resins include acrylate-based, methacrylate-based, epoxy-based, vinyl-based monomers or oligomers, or those obtained by applying energy to a mixture of monomers and oligomers and curing them. When setting the conductive layer 5 to a refractive index lower than that of the transparent base layer 1, for example, a urethane acrylate resin can be used as an ultraviolet curable resin having a low refractive index.

  Examples of the binder resin used in the solvent-type liquid composition (2) include cellulose resins such as ethyl cellulose and carboxymethyl cellulose, acrylic resins, and vinyl resins. The refractive index of the conductive layer 5 is determined by the binder resin. When the conductive layer 5 is set to a refractive index lower than that of the transparent substrate layer 1, a binder resin having a low refractive index is used, for example, polytrifluorinated chloride. Fluorine resins such as ethylene, polytetrafluoroethylene, tetrafluoroethylene, hexafluoroethylene copolymer resin, silicon resin, and the like can be used.

  Further, as the binder resin, the liquid energy curable resin mentioned as the resin used in the solvent-free liquid composition (1) can also be used. That is, after drying the solvent, it can be made to function as a binder resin by irradiating energy and curing. When setting the conductive layer 5 to a refractive index lower than that of the transparent base layer 1, for example, a urethane acrylate resin can be used as an ultraviolet curable resin having a low refractive index.

<Embodiment 2>
An example of the front filter configured when the optical film of the present invention is applied to a display device is shown in FIG. The front filter includes an optical film 10, a toning layer 11, a near infrared absorption layer 12, and a reflection reduction layer 13. The optical film 10 side faces the display panel, and the reflection reducing layer 13 is arranged to face the viewer. The optical film 10 has the configuration and function as described in the first embodiment.

  The near-infrared absorption layer 12 and the toning layer 11 are each for the purpose of cutting near-infrared light radiated from the panel to a level where there is no practical problem and for the purpose of selectively cutting unnecessary discharge gas emission. Installed. The characteristics of these layers can be adjusted by kneading the pigment on a substrate such as a resin film, or applying and drying a pigment coated with a resin and a solvent on a substrate such as a resin film. That is, a dye that absorbs near infrared light may be used for cutting near infrared light, and a dye that absorbs a wavelength corresponding to the light emission may be used for cutting emission light emission.

  The reflection reducing layer 13 is provided to prevent an image from becoming difficult to be seen due to the reflection of a lighting fixture or the like, and is either antireflection or antiglare, or antireflection antiglare having both characteristics. It has one characteristic.

<Embodiment 3>
The structure of the display device provided with the optical film in Embodiment 3 will be described with reference to a cross-sectional view shown in FIG. The optical film 10 in the figure has the configuration and function as described in the first embodiment.

  In the present embodiment, the optical film 10 is bonded to the (plasma) display panel 15 by the adhesive layer 14. The display panel 15 includes a chassis 16 provided on the back surface, and the outer peripheral electrode portion 3 of the optical film 10 is electrically connected to the chassis 16 via a double-sided adhesive conductive tape 17 and thereby grounded.

  Thus, electromagnetic waves can be efficiently shielded by electrically connecting the optical film 10 and the chassis 16 and grounding them. That is, the electromagnetic wave absorbed in the conductive layer 5 generates a new charge, and this charge is prevented from becoming a new electromagnetic wave generation source. The generated charge can be quickly released to the outside. it can.

  In the present embodiment, in order to show the grounding structure of the conductive layer 5, only the optical film 10 is mounted on the display panel 15. However, the optical film 10, which is the same as that in the second embodiment, is prepared. A form in which a front filter composed of the color layer 11, the near infrared absorption layer 12, and the reflection reduction layer 13 is mounted on the display panel 15 is desirable.

  The fixing method of the display panel 15 and the optical film 10 is not particularly limited, but an adhesive layer having an area that completely covers the image display area in order to eliminate the step caused by the double-sided adhesive conductive tape 17. It is desirable to be fixed by.

  Next, specific examples of the front filter using the optical film of the present embodiment will be described. However, the present invention is not limited to these examples.

[Example]
(Production of optical film)
As the transparent support substrate 6 shown in FIG. 5A, a single-sided easily-adhesive polyester film (Cosmo Shine A4100 manufactured by Toyobo Co., Ltd., film thickness 100 μm) having a width of 550 mm was prepared. A liquid ultraviolet-curing resin (PAK-02 manufactured by Toyo Gosei Co., Ltd.) was applied to the easy-adhesion treated surface of this film so that the film thickness after curing was 150 μm.

  Next, a roll plate for forming grooves in the liquid ultraviolet curable resin was prepared. The roll plate includes a convex line for a horizontal groove 7 having a trapezoidal cross section disposed along the roll rotation direction, and a vertical groove 8 having a cross section disposed along a direction orthogonal to the roll rotation direction. Convex lines are arranged in a rectangular area, and a convex part for the outer peripheral groove 9 having a rectangular frame shape connected to these convex lines is arranged on the outer periphery of the area.

  The convex lines for the horizontal grooves 7 are arranged at a line pitch of 70 μm along the roll rotation direction, and have a bottom width of 20 μm, a top width of 10 μm, and a height of 100 μm. The convex lines for the vertical grooves 8 are arranged at a line pitch of 70 μm along the direction orthogonal to the roll rotation direction, and have a bottom width of 20 μm, a top width of 10 μm, and a height of 40 μm. The rectangular area is 520 mm × 950 mm. The convex portion for the outer peripheral groove 9 has a width of 10 mm and a height of 40 μm.

By pressing this roll plate against the coating surface of the film coated with the above-mentioned ultraviolet curable resin, and further irradiating only the part where the roll plate and the coating film are in contact with each other, in the form of roll-to-roll, The film roll which has the transparent base material layer 1 in which the following groove shape was formed was obtained.
(1) Transparent base material layer 1
Film thickness 150μm
Width 550mm
(2) Horizontal groove 7
Groove line width (surface side of transparent resin film): 20 μm
Groove line width (side far from the surface of the transparent resin film): 10 μm
Groove depth: 100 μm
Groove pitch: 70 μm
(3) Vertical groove 8
Groove line width (surface side of transparent resin film): 20 μm
Groove line width (side far from the surface of the transparent resin film): 10 μm
Groove depth: 40 μm
Groove pitch: 70 μm
(4) Outer peripheral groove 9
Groove line width: 10 mm
Groove depth: 40 μm
Next, for each groove 7, 8, 9 of the transparent substrate layer 1, 30 parts by weight of carbon particles having an average particle diameter of 50 nm, urethane acrylate binder resin (V- 9520) After filling and drying a liquid composition consisting of 10 parts by weight and 60 parts by weight of butyl carbitol using a blade, the urethane acrylate binder resin is cured by irradiating with ultraviolet rays, whereby the transparent substrate layer 1 In the grooves 7, 8 and 9, the light absorbing layer 4 was formed at the bottom, leaving a space at the top.

  Next, 85 parts by weight of silver particles having an average particle diameter of 2 μm and urethane which is a liquid ultraviolet curable resin with respect to the spaces of the grooves 7, 8 and 9 of the transparent substrate layer 1 on which the light absorption layer 4 is formed. After filling a liquid composition consisting of 15 parts by weight of an acrylate binder resin (manufactured by DIC, V-9520) using a blade, the urethane acrylate binder resin is cured by irradiating with ultraviolet rays, thereby forming grooves 7, Conductive layer 5 was formed in 8 and 9.

  Through the above steps, a horizontal linear portion 2a having a height of 100 μm and a vertical linear portion 2b having a height of 40 μm are arranged in an area of 520 mm × 950 mm, and further, these horizontal linear portions 2a and vertical lines are arranged on the outer periphery of this area. The optical film in which the outer peripheral electrode portion 3 having a width of 10 mm and a height of 40 μm connected to the shape portion 2 b was disposed was obtained. The horizontal linear portion 2a and the vertical linear portion 2b have a trapezoidal cross-sectional shape in which the light absorption layer 4 and the conductive layer 5 are stacked (line width 20 μm on the side where the conductive layer 5 is exposed, line width 10 μm on the opposite side) And the pitch is 70 μm.

(Preparation of front filter)
The near-infrared absorbing film (near-infrared absorbing layer 12 in FIG. 6) was produced by a general method. That is, a near-infrared absorbing layer composed of a near-infrared absorbing dye and an acrylic binder resin is formed on the surface of the antiglare film (Dai Nippon Printing Co., Ltd., PET DS-LR) where the antiglare layer is not formed by coating. As a result, a near-infrared absorbing film subjected to antiglare treatment was obtained. Further, an adhesive containing a toning pigment is applied to the surface of the film on which the near-infrared absorbing layer 12 is formed, and then bonded to the film roll of the optical film 10 described above. A front filter of 550 mm × 980 mm was produced by cutting along the outside of the part 3.

[Comparative Example 1]
In the production process of the optical film of the above example, instead of the light absorption layer 4 and the conductive layer 5, a light absorption layer / conductive layer was formed in each groove 7, 8, 9 of the transparent substrate layer 1. That is, 60 parts by weight of silver particles having an average particle diameter of 2 μm, 5 parts by weight of carbon particles having an average particle diameter of 50 nm, and urethane acrylate, which is a liquid ultraviolet curable resin, for each groove 7, 8, 9 of the transparent substrate layer 1 A liquid composition comprising 10 parts by weight of a binder resin (manufactured by DIC, V-9520) and 25 parts by weight of butyl carbitol was filled and dried using a blade. Then, the light absorption layer and the conductive layer were formed by irradiating ultraviolet rays to cure the urethane acrylate binder resin. About other processes, the front filter was produced by the same method as the above-mentioned example.

[Comparative Example 2]
In the production process of the optical film of the above example, the roll plate to be used was changed so that the depth of the vertical groove 8 of the transparent substrate layer 1 was 100 μm. Otherwise, a front filter was produced in the same manner as in the above example.

[Comparative Example 3]
In the production process of the optical film of Comparative Example 1, the roll plate to be used was changed so that the depth of the vertical groove 8 of the transparent base material layer 1 was 100 μm and the line pitch was 300 μm. Otherwise, a front filter was prepared in the same manner as in Comparative Example 1.

[Comparative Example 4]
(Preparation of electromagnetic shielding film)
By performing gravure printing on a PET film having a width of 550 mm using an intaglio having a groove shape with a line width of 20 μm and a silver paste (Fujikura Kasei Co., Ltd., Dotite XA-9053), a line width of 20 μm, a thickness of 3 μm, An electromagnetic wave shielding film having a silver mesh pattern with a line pitch of 300 μm was obtained.

  Instead of the optical film, this electromagnetic wave shielding film was used, and a near-infrared absorbing film was bonded to the surface of the electromagnetic wave shielding film where the silver mesh was not formed. Other than that, the front filter was produced by the same method as the above-mentioned example.

  Table 1 shows the results of tests performed on the front filters obtained in the above Examples and Comparative Examples 1 to 4.

  The surface resistance value representing the electromagnetic wave shielding performance is a value measured using a 4-probe resistivity meter (Made by Mitsubishi Chemical, Loresta GP) on the surface side of the optical film where the conductive layer 5 is exposed.

  The viewing angle was evaluated by comparing the brightness obtained at each viewing angle relative to the brightness obtained in front of the display with the front display attached to the plasma display and displaying the plasma display in white. . That is, using a spectral luminance meter (Specular Radiance Meter CS-1000, manufactured by Konica Minolta Holdings Co., Ltd.), first, the luminance was measured directly in front of the display, and then the luminance was measured sequentially on a concentric circle centering on the display device. The angle at which the brightness was half that of the brightness directly in front was taken as the viewing angle under each condition. Therefore, it is desirable that the angle value obtained by this measurement is larger.

  The contrast was calculated by comparing the brightness when the display device was lit white and turned off under a fluorescent lamp. That is, each contrast was calculated by measuring the emission spectrum when the panel was turned on and off using a spectral luminance meter (Specular Radiance Meter CS-1000, manufactured by Konica Minolta Holdings, Inc.). In (Table 1), the contrast obtained in Comparative Example 3 to which the contrast enhancement function is not provided is 100, and the numerical values of the respective conditions are described as relative values. The larger the relative value based on the measurement result, the better the bright place contrast, and a clearer image can be provided even in a bright place.

  From Table 1, it can be seen that in the examples, very good results were shown in terms of sheet resistance, field of view, and contrast. In contrast, the sheet resistance and contrast in Comparative Example 1, the viewing angle in Comparative Example 2, the sheet resistance and contrast in Comparative Example 3, and the contrast in Comparative Example 4 were inferior to those of the Examples.

  According to the optical film of the present invention, it is possible to achieve both a high electromagnetic shielding property and a bright contrast enhancement function and to ensure a wide viewing angle, and is suitable for constituting a front filter of a display device such as a plasma display. .

DESCRIPTION OF SYMBOLS 1 Transparent base material layer 1a Transparent material layer 2 Bifunctional linear part 2a Horizontal linear part 2b Vertical linear part 3 Peripheral electrode part 4 Light absorption layer 5 Conductive layer 6 Transparent support base material 7 Horizontal groove 8 Vertical groove 9 Peripheral groove 10 Optical film 11 Toning layer 12 Near infrared absorption layer 13 Reflection reduction layer 14 Adhesive layer 15 Plasma display panel 16 Chassis 17 Double-sided adhesive conductive tape

Claims (4)

A display panel for displaying optical images;
A front filter disposed in front of the display panel;
The front filter is configured using an optical film that includes a transparent base layer and a bifunctional linear portion provided to form a lattice in the plane of the transparent base layer,
The bifunctional linear part is a laminated structure including a light absorption layer and a conductive layer, and has a trapezoidal or triangular cross-sectional shape in which the side of the light absorption layer is thinner than the side of the conductive layer,
The plurality of horizontal linear portions and vertical linear portions forming the lattice of the bifunctional linear portions are each arranged in parallel at a constant interval,
The display device according to claim 1, wherein a height of the vertical linear portion is lower than a height of the horizontal linear portion.   The display device according to claim 1, wherein a height of the vertical linear portion is set in a range of 1/10 to 1/2 with respect to a height of the horizontal linear portion.   A frame-shaped outer peripheral electrode portion is disposed around a region where the bifunctional linear portion is formed, and the outer peripheral electrode portion has a laminated structure including the light absorption layer and the conductive layer, and the bifunctional linear shape The display device according to claim 1, wherein the conductive layer of the portion is connected to the conductive layer of the outer peripheral electrode portion. It is a manufacturing method of the optical film used for the display apparatus of Claim 1, Comprising:
A first step of forming grooves corresponding to the horizontal linear portion and the vertical linear portion in the transparent base layer;
Filling the groove of the transparent substrate layer with a liquid composition containing a light-absorbing material, a binder resin and a solvent and drying the solvent, the light comprising the light-absorbing material and the binder resin at the bottom of the groove A second step of forming an absorbent layer;
And a third step of filling the groove of the transparent base material layer on which the light absorption layer is formed with a liquid composition containing a conductive material to form the conductive layer. The manufacturing method of the optical film to be used.

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