JP2015069158A - Optical film, image display device, and method for manufacturing the optical film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure sufficient flexibility in the case that a circularly polarizing plate and a touch panel sensor film are integrated to constitute an optical film.SOLUTION: An optical film 3 is provided in which a circularly polarizing plate 6 and a touch panel sensor film 7 are laminated. The circularly polarizing plate 6 includes a linearly polarizing plate 15 and a 1/4 wavelength plate 17 that are laminated. The 1/4 wavelength plate 17 includes a 1/4 wavelength phase difference layer 21 that is made by a polymeric film material (21) having at least optical anisotropy with inverse dispersion characteristics and that gives a phase difference of a 1/4 wavelength to transmitted light.

Description

  The present invention relates to an optical film made of a laminate of an antireflection film using a circularly polarizing plate and a sensor film for a touch panel.

  Conventionally, regarding an image display device, a method has been proposed in which an optical film made of a circularly polarizing plate is arranged on the panel surface (viewer side surface) of an image display panel, and reflection of extraneous light is reduced by this optical film. Here, this optical film is composed of a laminate of a linear polarizing plate and a quarter-wave plate, and converts external light directed to the panel surface of the image display panel into linearly-polarized light by the linear polarizing plate, followed by a quarter-wave plate. Convert to circularly polarized light. Here, the extraneous light by the circularly polarized light is reflected by the surface of the image display panel or the like, but the rotation direction of the polarization plane is reversed during the reflection. As a result, contrary to the arrival time, this reflected light is converted into linearly polarized light in the direction shielded by the linear polarizing plate by the quarter wavelength plate, and then shielded by the subsequent linear polarizing plate. Outgoing emission is significantly suppressed.

  With regard to this optical film, Patent Document 1 and the like include a 1/2 wavelength phase difference layer that imparts a phase difference of ½ wavelength to transmitted light, and a 1 / wavelength that imparts a phase difference of ¼ wavelength to transmitted light. A method has been proposed in which a quarter-wave plate is formed by laminating four-wavelength retardation layers to use a liquid crystal material having a positive dispersion characteristic so that the quarter-wave plate functions with a reverse dispersion characteristic. Here, the reverse dispersion characteristic is a wavelength dispersion characteristic in which the phase difference in transmitted light is smaller as the wavelength is shorter, and more specifically, retardation at a wavelength of 450 nm (R450) and retardation at a wavelength of 550 nm (R550). Is a characteristic in which R450 <R550. Patent Documents 2 and 3 propose polymer films that can be applied to quarter-wave plates and the like and have optical anisotropy of reverse dispersion characteristics. Patent Documents 4 and 5 propose a device for reducing the thickness of the linearly polarizing plate.

  In this type of image display device, a configuration in which a touch panel sensor film is disposed on the panel surface of the image display panel is also employed. This sensor film for a touch panel is made of a transparent electrode material made of ITO (Indium Tin Oxide) so as to be arranged on the panel surface of the image display panel so that deterioration of visibility can be effectively avoided. . Patent Document 6 and the like propose a method of forming an electrode with a metal electrode material instead of ITO. Patent Documents 7 and 8 refer to disposing a circularly polarizing plate with respect to this type of touch panel sensor film.

  By the way, in recent years, organic EL panels, which are this type of image display device, are being provided with flexible sheet shapes. In such an image display device having a flexible sheet shape, for example, an image can be displayed in a state where the entire image is bent outward or bent in the opposite direction. It is considered that the application field of this type of image display apparatus can be expanded.

  However, in the case where an image is displayed in a state where the whole is folded outward or bent in the opposite direction, it is necessary to significantly reduce the reflection of external light as compared with the conventional case. Thus, in such an image display device having a flexible sheet shape, it is considered necessary to effectively avoid the influence of external light by disposing the optical film by the circularly polarizing plate described above. . In particular, in an organic EL panel, the reflection of extraneous light by the internal electrodes is remarkable, so that it is desirable to apply this type of optical film.

  In addition, from the viewpoint of improving the user interface, it is desirable to provide a touch panel sensor film integrally in an optical film applied to such a flexible organic EL panel. It is demanded not to impair the flexibility.

JP-A-10-68816 JP 2007-171756 A JP 2010-230832 A JP 2012-73563 A JP 2012-68677 A JP 2010-257350 A JP 2007-140796 A JP 2009-176198 A

  This invention is made | formed in view of such a condition, When integrating a circularly-polarizing plate and the sensor film for touchscreens and comprising an optical film so that sufficient flexibility can be ensured. To do.

  The present inventor has intensively studied to solve the above problems, and has come up with the idea that a quarter-wave plate is produced using a polymer film material having optical anisotropy of reverse dispersion characteristics. The invention has been completed.

(1) In an optical film in which a circularly polarizing plate and a touch panel sensor film are laminated,
The circularly polarizing plate is
A linear polarizing plate and a quarter wave plate are laminated,
The quarter-wave plate is
A quarter-wave retardation layer that imparts a quarter-wave phase difference to transmitted light and functions as a quarter-wave plate is made of a polymer film material having optical anisotropy of reverse dispersion characteristics. It was made.

  According to (1), the thickness of the entire film is reduced by preparing a quarter-wave retardation layer from a polymer film material having optical anisotropy of reverse dispersion characteristics to produce a quarter-wave plate. Thus, flexibility can be ensured and sufficient antireflection can be achieved in a wide wavelength band.

(2) In (1),
The sensor film for the touch panel is
An electrode was made of a metal electrode material.

  According to (2), flexibility can be further secured by ensuring resistance to bending and the like.

(3) In (1) or (2),
The quarter-wave plate is
Furthermore, a + C plate is provided.

  According to (3), the optical characteristic in the oblique direction can be brought close to the optical characteristic in the front direction, and the viewing angle characteristic can be improved.

(4) In any one of (1), (2) and (3),
The + C plate is
Between the said sensor film for touchscreens and the said 1/4 wavelength phase difference layer, or the said 1/4 wavelength phase difference layer, it was provided in the opposite side to the said sensor film for touchscreens.

  According to (4), when the touch panel sensor film is disposed on the image display panel so as to be on the image display panel side, on the contrary, the circularly polarizing plate is disposed on the image display panel side. In this case, the viewing angle characteristic can be improved by a more specific configuration, and a specific effect can be obtained according to the arrangement position of the + C plate.

  (5) An image display device in which the optical film according to any one of (1), (2), (3), and (4) is disposed on the image display panel surface.

  According to (5), it is possible to obtain an image display device in which flexibility is sufficiently secured by disposing an optical film that is a laminate of a sensor film for a touch panel and a circularly polarizing plate.

(6) In (5),
The image display panel is a flexible organic EL panel.

  According to (6), it is possible to obtain an image display device in which an optical film made of a laminate of a sensor film for a touch panel and a circularly polarizing plate is arranged with a more specific configuration to ensure sufficient flexibility. it can.

(7) In the manufacturing method of the optical film which laminated | stacked the circularly-polarizing plate and the sensor film for touchscreens,
A first laminating step of laminating a substrate made of a polymer film material having optical anisotropy of reverse dispersion characteristics on a circularly polarizing plate or the sensor film for touch panel;
A second lamination step of laminating the laminate produced in the first lamination step with the sensor film for a touch panel or the circularly polarizing plate.

  According to (7), the quarter-wave retardation layer is made of a polymer film material having optical anisotropy of reverse dispersion characteristics to form a circularly polarizing plate, thereby reducing the overall thickness. It is possible to prevent reflection sufficiently in a wide wavelength band, thereby reducing the overall thickness and ensuring flexibility.

  ADVANTAGE OF THE INVENTION According to this invention, when integrating a circularly-polarizing plate and the sensor film for touchscreens and comprising an optical film, sufficient flexibility can be ensured.

It is sectional drawing which shows the image display apparatus which concerns on 1st Embodiment of this invention. It is sectional drawing which shows the optical film applied to the image display apparatus of FIG. It is a figure which shows the other example of the sensor film for touchscreens. It is a figure where it uses for description of the optical film of FIG. It is a figure where it uses for description of the manufacturing process of the optical film of FIG. It is a figure which shows the circularly-polarizing plate which concerns on 2nd Embodiment of this invention. It is a figure which shows the image display apparatus which concerns on 2nd Embodiment of this invention.

[First Embodiment]
[Optical film and image display device]
FIG. 1 is a diagram showing an image display device according to the first embodiment of the present invention, and FIG. 2 is a diagram showing an optical film 3 according to the image display device. In the image display device 1, the optical film 3 is disposed on the panel surface (viewer side surface) of the image display panel 2. Here, the image display panel 2 is a flexible sheet-like organic EL panel, and displays a desired color image. More specifically, the image display panel 2 is manufactured using a transparent film or a thin glass plate (thickness of 50 μm or less) instead of a glass substrate used for a flat organic EL panel. By doing so, it is configured in a sheet shape having sufficient flexibility. The optical film 3 is not limited to the flexible sheet-like organic EL panel 2 but can be widely applied to various image display panels such as a flat organic EL panel and a liquid crystal display panel. The optical film 3 is peeled off the separator film to expose the adhesive layer 4 made of a pressure-sensitive adhesive that is a pressure-sensitive adhesive, and is then adhered and held on the panel surface of the image display panel 2 by the adhesive layer 4. . Various adhesives and pressure-sensitive adhesives such as UV curable resins and thermosetting resin agents can be widely applied instead of pressure sensitive adhesives, and UV curable resins are applied from the viewpoint of reducing the overall thickness. In this case, it can be produced with a thickness of about 1 μm.

  The optical film 3 is composed of a laminate in which a circularly polarizing plate 6 and a touch panel sensor film 7 are bonded together with an adhesive layer 11, and the touch panel sensor film 7 is disposed on the image display panel 2 side. Here, the sensor film 7 for the touch panel is configured to hold the electrodes 8X and 8Y in the X direction and the Y direction so as to face each other with a predetermined distance therebetween. In this embodiment, the electrodes 8X and 8Y are It is composed of a metal electrode material such as copper. Thereby, in this embodiment, the flexibility of the sensor film 7 for touch panels is sufficiently ensured, and the flexibility of the optical film 3 and further the flexibility of the image display device 1 are ensured.

  The sensor film 7 for a touch panel is configured by forming electrodes 8X and 8Y on base materials 9X and 9Y made of a transparent film and laminating the base materials 9X and 9Y with an adhesive layer 10, respectively. Here, the substrate 9X and 9Y can be applied with a transparent film such as a PET film or TAC (triacetylcellulose), but from the viewpoint of sufficiently exhibiting the antireflection function by the circularly polarizing plate 6, the optical anisotropy. It is preferable to apply a small material.

  For the electrodes 8X and 8Y, silver, copper, gold, aluminum or the like is preferably used. The electrodes 8X and 8Y may be a single metal or alloy, or may be formed by binding metal particles with a binder. In addition, as for the electrodes 8X and 8Y, a rust prevention process is given to the metal surface as needed.

  The electrodes 8X and 8Y can be produced by photolithography (etching), pattern printing, transfer, self-assembly, and the like. Here, when producing by photolithography, a metal layer is produced on the base materials 9X and 9Y by lamination, vapor deposition, sputtering, etc., and this metal layer is etched and produced. As a method of producing by pattern printing, a method of printing a conductive ink in a predetermined pattern, a method of printing a material having a catalytic function of electroless plating with the shape of an electrode pattern, and then electroless plating of a conductive metal, Examples include a method of printing an electroless plating catalyst and a material forming an adduct and then adding the catalyst to perform electroless plating treatment. Examples of the conductive ink include silver paste, copper paste, and conductive polymer. Examples of the material having a catalytic function include ink containing catalyst particles such as palladium and particles having catalyst particles supported on the surface. Examples of the material forming the adduct with the catalyst include ink containing silver, a conductive polymer, an adsorbing material, and the like. Examples of the metal forming the electroless plating layer include conductive metals such as copper, nickel, and silver. Although any method can be applied as the pattern printing method depending on the required pattern accuracy, screen printing, intaglio offset printing, a method of transferring from the intaglio using a UV curing primer, or the like is preferably used. The adhesive layers 10 and 11 can be widely applied to various adhesives and pressure-sensitive adhesives such as UV curable resins and thermosetting resin agents, but from the viewpoint of reducing the overall thickness, UV curable resins are applied. It is preferable to do.

  In addition, as shown in FIG. 3, the sensor film 7 for touch panels may produce the electrodes 8X and 8Y on both surfaces of the base material 9XY, respectively. In this case, one electrode (the electrode 8Y in the example of FIG. 2) is prepared on the other base material, and this electrode 8Y is transferred and disposed on the base material 9XY related to the other electrode 8X by the adhesive layer 12. May be.

  The circularly polarizing plate 6 is configured by bonding a linearly polarizing plate 15 and a quarter-wave plate 17 with an adhesive layer 18. Here, the linearly polarizing plate 15 is provided with an optical functional layer that functions as a linearly polarizing plate after the lower surface side of a substrate made of a transparent film such as TAC (triacetylcellulose) is saponified. In place of this, poly (meth) acrylate, poly (meth) butyl acrylate, methyl (meth) acrylate-butyl (meth) acrylate copolymer, methyl (meth) acrylate-styrene A resin such as an acrylic resin such as a copolymer, a glass such as soda glass, potash glass, lead glass, and quartz glass can be applied. The optical functional layer is produced, for example, by adsorbing and orienting iodine compound molecules on a film material made of polyvinyl alcohol (PVA). In addition, the linearly polarizing plate 15 may be configured as disclosed in JP 2012-73563 A, JP 2012-68677 A, or the like.

  The quarter-wave plate 17 is composed of a transparent polymer film material having optical anisotropy of reverse dispersion characteristics, and a quarter-wave retardation layer 21 that imparts a quarter-wave phase difference to transmitted light. The quarter-wave retardation layer 21 is provided and functions as a quarter-wave plate. Here, as shown in FIG. 4, the quarter-wave retardation layer 24 has an angle of 45 degrees counterclockwise with respect to the absorption axis of the linearly polarizing plate 15 indicated by the arrow. It is arranged to form. Thereby, the circularly polarizing plate 6 is configured to sufficiently prevent the reflection of extraneous light in a wide wavelength band. Here, the transparent polymer film material having the optical anisotropy of the reverse dispersion characteristic includes various materials such as a polycarbonate, a film material disclosed in JP 2007-171756 A, JP 2010-230832 A, and the like. A stretched film material can be legalized.

  Further, the ¼ wavelength plate 17 is provided with a + C plate 22, whereby the optical characteristics in the oblique direction are brought closer to the optical characteristics in the front direction, and the optical characteristics are further improved. Here, the optical characteristics in the oblique direction are an antireflection rate, a color of the display screen, and the like. Note that the optical characteristics of the + C plate are expressed by nx = ny <nz. However, nx and ny (nx ≧ ny) are refractive indexes in the in-plane direction, and nz is a refractive index in the thickness direction.

  More specifically, the quarter-wave plate 17 is sequentially provided with a quarter-wave retardation layer 21, an alignment film 25 for preparing a C plate, and a + C plate 22 from the linear polarizing plate 15 side.

  The alignment film 25 is an alignment film having a function of homeotropically aligning the molecular axes of liquid crystal molecules applied to the + C plate 22 by being provided as a coating film on the substrate. For example, a polyimide alignment film, an alignment film made of an LB film, or the like can be applied. Specifically, examples of the constituent material of the alignment film 25 include silane coupling systems such as lecithin, silane surfactants, titanate surfactants, pyridinium salt polymer surfactants, and n-octadecyltriethoxysilane. Composition for vertical alignment film, composition for polyimide vertical alignment film such as soluble polyimide having long chain alkyl group or alicyclic structure in side chain and polyamic acid having long chain alkyl group or alicyclic structure in side chain Is mentioned. More specifically, as a composition for a vertical alignment film, a polyimide vertical alignment film composition “JALS-2021” or “JALS-204” manufactured by GS Co., Ltd., “manufactured by Nissan Chemical Industries, Ltd.” Commercial products such as “RN-1517”, “SE-1211”, and “EXPOA-018” can be applied. Note that the vertical alignment film 25 may be omitted depending on the liquid crystal compound applied to the + C plate 22.

  The + C plate 22 can be applied with a retardation layer made of a rod-like liquid crystal, an acrylic-based stretched film, or the like, and more specifically, any one of the following compounds (1) to (13) can be applied. it can. The + C plate 22 is formed by applying a liquid crystal material coating liquid and then solidifying (curing) the liquid crystal material while maintaining the refractive index anisotropy by the alignment regulating force of the alignment film 25.

  In this embodiment, the circularly polarizing plate 6 is formed by sequentially forming an alignment film 25 and a + C plate 22 on the film material using the film material related to the quarter-wave retardation layer 21 as a base material. Thus, the entire thickness can be sufficiently reduced to ensure sufficient flexibility.

  That is, in the circularly polarizing plate 6, the alignment film 25 is produced by applying the coating liquid related to the alignment film 25 to the film material related to the quarter-wave retardation layer 21 and drying and curing it. Subsequently, a liquid crystal compound coating liquid is applied onto the alignment film 25 and then dried and cured to produce the + C plate 22, whereby the quarter-wave plate 17 is produced.

  As shown in FIG. 5, in the first laminating step, the optical film 3 has a quarter-wave plate 17 attached to the linearly polarizing plate 15 by the adhesive layer 18 (FIG. 6A), whereby circularly polarized light is obtained. A plate 6 is produced. In another process, the touch panel sensor film 7 is prepared. In the second lamination process, the touch panel sensor film 7 and the circularly polarizing plate 6 are integrated by the adhesive layer 11, and the adhesive layer 4 and the separator film are provided. (FIG. 6B). Thereafter, the separator film is peeled off and placed on the panel surface of the image display panel 2 (see FIG. 1).

  According to this embodiment, by making a quarter-wave plate using a polymer film material having optical anisotropy of reverse dispersion characteristics, the overall thickness is reduced and sufficient flexibility is achieved. Can be secured. Further, the layer structure having optical anisotropy that impairs the function of the circularly polarizing plate can be reduced, and the antireflection effect can be further ensured in a wide wavelength band.

  Further, by making a sensor film for a touch panel using a metal electrode material such as copper, it is possible to further ensure flexibility. That is, when an electrode is made of ITO to constitute a sensor film for a touch panel, it is difficult to ensure sufficient flexibility due to cracks in the ITO electrode. For example, an image display panel using a flexible organic EL panel When applied to the above, the flexibility of the image display panel is remarkably impaired. Thereby, a sensor film for a touch panel can be produced with a metal electrode such as copper, and cracks can be effectively avoided, and as a result, resistance to bending and the like can be ensured. However, even when a sensor film for a touch panel is produced with a metal electrode such as copper and the resistance to bending or the like is ensured in this way, simply configuring a circularly polarizing plate depends on the thickness of the circularly polarizing plate. Flexibility is impaired. However, when a quarter-wave plate is made using a polymer film material having optical anisotropy of reverse dispersion characteristics, the quarter-wave plate related to the circularly polarizing plate is phase-difference due to the liquid crystal compound. The base material in the case of producing a layer can be abbreviate | omitted and it can comprise by this, thickness can be made thin enough and flexibility can be ensured. Thus, sufficient flexibility can be ensured.

  Moreover, the sensor film 7 for touch panels can be arrange | positioned at the image display panel side of the circularly-polarizing plate 6, and the reflection of the electrode of the sensor film 7 for touch panels can fully be suppressed, and, thereby, the electrode of the sensor film 7 for touch panels can be used. The configuration of the touch sensor film 7 can be simplified by omitting the blackening process that makes it difficult to view.

  In addition, by reducing the thickness of the quarter-wave plate in this way, the touch panel sensor film 7 can be disposed on the image display panel side of the circularly polarizing plate 6 to sufficiently secure the sensitivity of the touch panel sensor film 7. it can.

  Further, the viewing angle characteristics can be improved by the arrangement of the + C plate. Further, by arranging this + C plate on the sensor film side for the touch panel of the retardation layer, it is possible to efficiently reduce a change in color viewed from an oblique direction.

[Second Embodiment]
FIG. 6 is a diagram showing a circularly polarizing plate 36 according to the second embodiment of the present invention in comparison with FIG. In this embodiment, the circularly polarizing plate 36 is disposed in place of the circularly polarizing plate 6. This embodiment has the same configuration as that of the first embodiment except that the configuration regarding the circularly polarizing plate 36 is different.

  The circularly polarizing plate 36 is formed so that the linearly polarizing plate 15 side becomes the + C plate 22. More specifically, the circularly polarizing plate 36 includes, in order from the linearly polarizing plate 15, the adhesive layer 18, the + C plate 22, the alignment film 25, and the quarter retardation layer 21 made of a polymer film having optical anisotropy of reverse dispersion characteristics. Is provided.

  According to this embodiment, even if the circularly polarizing plate is configured so that the linearly polarizing plate 15 side becomes the + C plate 22, the same effect as that of the first embodiment can be obtained.

[Third Embodiment]
FIG. 7 is a diagram for explaining an optical film manufacturing process according to the third embodiment of the present invention. In this embodiment, circularly polarizing plates 6 and 36 and a touch panel sensor film 7 are arranged from the image display panel 2 side. This embodiment has the same configuration as that of the first or second embodiment described above except that the configuration relating to the arrangement of the sensor film for touch panel 7 and the circularly polarizing plates 6 and 36 is different.

  That is, in this embodiment, circularly polarizing plates 3 and 36 are produced in the same manner as in the first or second embodiment described above, and the circularly polarizing plates 3 and 36 are integrated with the sensor film 7 for touch panel.

  In this embodiment, even when the touch panel sensor film 7 is arranged on the viewer side, the same effects as those of the above-described embodiment can be obtained. In this case, since the user can directly operate the touch panel sensor film 7, the sensitivity can be further improved and the operability can be improved.

Other Embodiment
The specific configuration suitable for the implementation of the present invention has been described in detail above. However, the present invention can be variously combined or modified with the configuration of the above-described embodiment without departing from the spirit of the present invention. Can do.

  That is, in the above-described embodiment, the case where the alignment film according to the retardation layer is manufactured by the shaping process has been described. it can.

  In the above-described embodiment, the case where the sensor film for the touch panel is manufactured using the metal electrode has been described. However, the present invention is not limited to this, and the present invention can be widely applied to a case where the sensor film is manufactured using ITO when it is practically sufficient. it can.

  Further, in the above-described embodiment, a case where a quarter-wave plate is laminated on a linear polarizing plate to produce a circularly polarizing plate and then laminated with a sensor film for a touch panel is described. The order may be changed, and the quarter wavelength plate may be laminated with the touch panel sensor film 7 and then laminated with the linear polarizing plate.

DESCRIPTION OF SYMBOLS 1, 60 Image display apparatus 2 Image display panel 3 Optical film 4, 10, 11, 12, 18 Adhesive layer 6 Circular polarizing plate 7 Sensor film for touch panels 8X, 8Y Electrode 9X, 9Y, 9XY Base material 15 Linear polarizing plate 17 1 / 4 wavelength plate 21 1/4 wavelength retardation layer 22 + C plate 25 Alignment film

Claims (7)

In an optical film in which a circularly polarizing plate and a sensor film for a touch panel are laminated,
The circularly polarizing plate is
A linear polarizing plate and a quarter wave plate are laminated,
The quarter-wave plate is
A quarter-wave retardation layer that imparts a quarter-wave phase difference to transmitted light and functions as a quarter-wave plate is made of a polymer film material having optical anisotropy of reverse dispersion characteristics. The produced optical film. The sensor film for the touch panel is
The optical film according to claim 1, wherein an electrode is made of a metal electrode material. The quarter-wave plate is
The optical film according to claim 1, further comprising a + C plate. The + C plate is
The optical film according to claim 4, provided between the sensor film for touch panel and the quarter-wave retardation layer, or on the opposite side of the quarter-wave retardation layer from the touch-panel sensor film. An image display device in which the optical film according to any one of claims 1, 2, 3, and 4 is disposed on a panel surface of an image display panel. The image display device according to claim 5, wherein the image display panel is a flexible organic EL panel. In the method for producing an optical film in which a circularly polarizing plate and a sensor film for a touch panel are laminated,
A first laminating step of laminating a substrate made of a polymer film material having optical anisotropy of reverse dispersion characteristics on a circularly polarizing plate or the sensor film for touch panel;
The manufacturing method of an optical film provided with the 2nd lamination process which laminates | stacks the laminated body created at the said 1st lamination process with the said sensor film for touch panels, or the said circularly-polarizing plate.

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