TWI888700B - Optical film with double-sided adhesive - Google Patents

Abstract

The optical film (50) with adhesive has a first adhesive layer (21) on the first main surface of an optical film (11) having a first main surface and a second main surface, and a second adhesive layer (22) on the second main surface of the optical film. On the first main surface of the optical film, there is a non-contact area (2x) where the first adhesive layer is not provided and the optical film is exposed, and a contact area where the first adhesive layer is attached to the optical film. The non-contact area is provided, for example, along the periphery of the optical film.

Description

Optical film with double-sided adhesive

The present invention relates to an optical film with adhesive layers on both sides of the optical film, and an image display device.

Liquid crystal display devices or organic EL (Electroluminescence) display devices are widely used as various image display devices such as mobile phones, smart phones, car navigation devices, monitors, and televisions. Liquid crystal display devices have a polarizing plate on the viewing side surface of the liquid crystal unit due to its display principle. In self-luminous display devices such as organic EL, there is no need to set a polarizing plate based on the principle of image display, but there is a case where a circular polarizing plate (a layered body of a polarizing plate and a 1/4 wavelength plate) is arranged on the viewing side surface of the unit in order to suppress the external light from being reflected by the metal electrode (cathode) and being viewed like a mirror.

Image display devices having a front transparent member such as a touch sensor or cover glass provided on the surface of the image display panel are becoming popular, and this structure is becoming mainstream for mobile or vehicle-mounted applications. By bonding the polarizing plate and the front transparent member via an adhesive layer, the refractive index difference at the interface is reduced, and the reduction in visibility due to reflection or scattering can be suppressed. In order to form such an image display device, a double-sided adhesive film is proposed, in which an adhesive layer is provided on one side of the polarizing plate for bonding to the image display unit and an adhesive layer is provided on the other side for bonding to the front transparent plate (for example, refer to patent document 1). [Prior art document] [Patent document]

[Patent Document 1] Japanese Patent Publication No. 2014-115468

[The problem the invention is trying to solve]

As the demand for narrower bezels of display devices increases, various studies have been conducted on wiring routing around the periphery of the screen or the placement of flexible printed wiring boards. On the other hand, there is a tendency that the space for components such as cover glass or casings with curved portions at the ends of the screen that can accommodate image display devices is becoming increasingly limited.

The present invention provides an image display device that can ensure the storage space of the constituent components, and an optical film used for the adhesive of the image display device. [Technical means for solving the problem]

The optical film with adhesive of the present invention is provided with adhesive layers on both sides of an optical film such as a polarizing plate. On at least one side of the optical film, there is a non-contact area where the adhesive layer is not partially provided and the optical film is exposed. When the optical film with adhesive on both sides is attached to the image display panel and the front surface transparent component, the non-contact area becomes a gap. By arranging the image display device components such as the electrical connection components such as the flexible printed wiring board (FPC), the curved surface part of the housing or the front surface transparent plate, the resin material, the conductive material, etc. in the gap, the space can be effectively utilized.

The double-sided adhesive optical film of the present invention has an optical film such as a polarizing plate, a first adhesive layer disposed on the first main surface of the optical film, and a second adhesive layer disposed on the second main surface of the optical film. On the first main surface of the optical film, there is a non-contact area where the first adhesive layer is not disposed. In an image display device, the optical film and the front surface transparent component or the image display unit are bonded via the first adhesive layer, and a gap is formed in the non-contact area where the first adhesive layer is not disposed. By arranging a printed wiring board, a front surface transparent component, a housing, a conductive paste, a resin material, etc. in the gap, space can be effectively utilized to achieve narrow margins and miniaturization.

[First embodiment] <Optical film with adhesive> The double-sided optical film with adhesive of the first embodiment has an area (non-contact area) along the periphery of the first main surface of the optical film where the first adhesive layer is not provided and the optical film is exposed, and an area (contact area) where the first adhesive layer is provided on the optical film.

Fig. 1A is a top view of a first main surface side of a double-sided adhesive optical film 51 of an embodiment, and Fig. 1B is a cross-sectional view along line B1-B2. The double-sided adhesive optical film 51 is provided with a first adhesive layer 21 on one main surface of the optical film 11, and a second adhesive layer 22 on the other main surface.

(Optical film) As the optical film 11, for example, a polarizing plate is used. In a general polarizing plate, a suitable transparent protective film is provided on one or both sides of the polarizing element as needed. As the polarizing element, for example, a dichroic substance such as iodine or a dichroic dye is adsorbed on a hydrophilic polymer film such as a polyvinyl alcohol film, a partially formalized polyvinyl alcohol film, or a partially saponified film of an ethylene-vinyl acetate copolymer, and the dichroic substance is oriented by stretching. As a transparent protective film provided on the surface of the polarizing element, it is preferred to use a material having excellent transparency, mechanical strength, and thermal stability such as a cellulose resin, a cyclic polyolefin resin, an acrylic resin, a phenylmaleimide resin, or a polycarbonate resin. As a transparent protective film for polarizing elements, optical anisotropic films such as phase difference plates can also be used.

The optical film 11 may also be formed by laminating a plurality of films through appropriate adhesive layers or adhesive layers. As optical films other than polarizing plates, films used to form image display devices such as phase difference films, viewing angle expansion films, viewing angle restriction (anti-peek) films, and brightness enhancement films may be listed. Touch sensors may also be provided in the optical film. In addition, a hard coating layer, an anti-reflection layer, an anti-glare layer, an anti-adhesion layer, etc. may also be provided on the surface of the optical film, and surface treatment for the purpose of improving adhesion may also be performed.

(Adhesive layer) The first adhesive layer 21 disposed on the first main surface of the optical film 11 and the second adhesive layer 22 disposed on the second main surface of the optical film 11 preferably contain an optically transparent adhesive. One of the first adhesive layer 21 and the second adhesive layer 22 is used for bonding the optical film 11 to the image display unit, and the other is used for bonding the optical film 11 to the front surface transparent component (transparent plate such as cover glass, touch sensor, etc.).

As the adhesive constituting the adhesive layers 21 and 22, an adhesive based on a polymer such as acrylic polymer, silicone polymer, polyester, polyurethane, polyamide, polyvinyl ether, vinyl acetate/vinyl chloride copolymer, modified polyolefin, epoxy, fluorine, natural rubber, synthetic rubber, etc. can be appropriately selected and used. In particular, in terms of excellent optical transparency, showing appropriate adhesive properties such as wettability, cohesion and adhesion, and excellent weather resistance or heat resistance, it is preferable to use an acrylic adhesive. The first adhesive layer 21 and the second adhesive layer 22 can also be formed by laminating a plurality of adhesive layers.

The adhesive constituting the first adhesive layer 21 and the second adhesive layer 22 may also be a photocurable adhesive that can be cured by light irradiation after being bonded to an adherend such as an image display unit or a front surface transparent component. For example, if a photocurable adhesive is used for bonding to a front surface transparent component having a raised portion such as decorative printing, the adhesive before light curing is bonded in a soft state and has a step-absorption property, thereby suppressing the mixing of bubbles near the raised portion. After bonding, the adhesive is photocured by irradiating UV (Ultraviolet) or the like, thereby improving the bonding reliability. The photocurable adhesive is preferably one that includes, for example, a polymer, a monomer or oligomer having a photopolymerizable functional group, and a photopolymerization initiator. As the monomer or oligomer having a photopolymerizable functional group, a crosslinking monomer having two or more polymerizable functional groups in one molecule may be used.

The thickness of the adhesive layers 21 and 22 is not particularly limited, and is generally about 5 to 500 μm. The thickness of the adhesive used for bonding the optical film 11 to the image display unit is preferably about 5 to 50 μm. The thickness of the adhesive used for bonding the optical film 11 to the front surface transparent component can be appropriately set according to the structure of the front surface transparent component. For example, when the front surface transparent component has a raised portion caused by decorative printing, etc., in order to prevent bubbles from mixing into the periphery of the raised portion, it is preferred to set the thickness of the adhesive layer to be 50 μm or more so that it has a step absorption property.

(Non-contact area) In the double-sided adhesive optical film 51 shown in FIG. 1 , the periphery of three of the four sides of the optical film 11, 11a ₂ , 11a ₃ and 11a ₄ , is a contact area where the first adhesive layer 21 is provided. The first adhesive layer 21 is not provided on the optical film 11 along the periphery of the side 11a ₁ extending in the y direction. In the non-contact area 2x, the main surface of the optical film 11 is exposed, and there is a gap on the optical film 11.

The end surface of the optical film 11 is aligned with the end surface of the first adhesive layer 21 along the periphery of the edges _11a2 , _11a3 and _11a4 . In the non-contact area 2x along the edge _11a1 , the end surface 21e of the first adhesive layer 21 is located further inward than the end surface 11e of the optical film 11. The end surfaces 11e, 21e extend in parallel along the edge _11a1 in the y direction.

The width _W1 of the non-contact area 2x, i.e., the offset of the end surface 21e of the first adhesive layer 21 from the end surface 11e of the optical film 11, can be set according to the shape or size of the component disposed in the non-contact area. From the perspective of effectively utilizing the periphery of the screen and the space near it, _W1 is preferably 10 μm or more, more preferably 50 μm or more, and further preferably 100 μm or more.

There is no particular upper limit for _W1 , and it can be set according to the size of the image display device or the screen size. For example, _W1 is preferably less than 10% of the length of the diagonal of the optical film, more preferably less than 5%, and further preferably less than 1%. In addition, _W1 is preferably less than 50 mm, more preferably less than 10 mm, further preferably less than 5 mm, and particularly preferably less than 1 mm. From the perspective of ensuring that the optical film 11 is bonded to the front surface transparent component and the like using the first adhesive layer 21 to prevent peeling, it is preferred that _W1 is as small as possible within a range that can avoid physical interference between the components of the image display device and the first adhesive layer.

The area of the optical film 11 is not particularly limited, but is generally about 5 to 25,000 ^cm2 . When the optical film 11 is rectangular, the length of the diagonal is about 3 to 250 cm. In particular, in a medium-sized or small-sized image display device with an area of less than 2,000 ^cm2 , the space-saving effect obtained by the structure of the present invention is greater.

When the optical film 11 is a rectangle, it can be a rectangle with long sides and short sides, or a square with four sides of equal length. The length of the long side of the rectangle is generally less than 10 times the length of the short side, and can be less than 5 times, less than 3 times, or less than 2 times. When the optical film is an optical anisotropic film such as a polarizing plate or a phase difference film, the direction of the optical axis such as the absorption axis or the retardation axis can be parallel or perpendicular to the extension direction of the side of the rectangle, or can form a specific angle with the extension direction of the side of the rectangle. When the optical film is a laminate of multiple films, the configuration of the optical axes of each film is not particularly limited, and can be parallel or orthogonal, or can form a specific angle. For example, in the case of a circular polarizing plate, the polarizing element and the quarter-wave plate are stacked so that the angle between the absorption axis direction of the polarizing element and the retarded axis direction of the quarter-wave plate becomes 45°.

In the optical film with adhesive on both sides of the first embodiment, a part of the area along the periphery of the optical film 11 is a non-contact area, and in other areas, a first adhesive layer 21 is attached to the periphery of the optical film 11, and the end of the first main surface is covered by the first adhesive layer 21. The area where physical interference between the adhesive and the components constituting the image display device should be avoided is set as the non-contact area, and the other area is a contact area where the adhesive layer 21 is also provided on the periphery of the optical film 11, thereby making it possible to reliably use the adhesive layer 21 to bond the optical film 11 to the cover glass, etc., and prevent peeling.

(Protective sheet) Figure 2 is a cross-sectional view of a double-sided adhesive optical film 451 having a protective sheet on an adhesive layer. A first protective sheet 41 is releasably attached to a first adhesive layer 21, and a second protective sheet 42 is releasably attached to a second adhesive layer 22. If the protective sheet is temporarily attached to the adhesive layer in this manner, the exposed surfaces of the adhesive layers 21 and 22 can be protected until the optical film 11 is attached to the adherend.

The protective sheets 41 and 42 are preferably made of plastic films such as polyethylene, polypropylene, polyethylene terephthalate, and polyester films. The thickness of the protective sheets 41 and 42 is usually 5 to 200 μm, preferably about 10 to 150 μm. The protective sheets may also be subjected to a peeling treatment using a silicone release agent or the like on the surface where they are bonded to the adhesive.

(Formation of adhesive layer and non-bonded area on optical film) As a method for setting the first adhesive layer 21 and the second adhesive layer 22 on the optical film 11, there can be listed a method of applying the adhesive composition on a peeling treatment sheet to form an adhesive layer and then transferring it to the optical film 11, a method of applying the adhesive composition on the optical film 11, etc. The applied adhesive composition can also be dried to remove the solvent, crosslinked, hardened, etc. as needed.

As a method of locally providing the non-contact area 2x on the main surface of the optical film 11, there can be listed a method of controlling the area where the first adhesive layer 21 is attached to the optical film 11, and a method of removing the adhesive layer in a specific area after attaching the first adhesive layer 21 to the entire main surface of the optical film. The non-contact area can also be formed by attaching an adhesive layer with a smaller area than the optical film to the optical film adjusted to a size for bonding with an image display device. In addition, the non-contact area can also be formed by removing a specific area of the adhesive layer provided on the entire surface of the optical film adjusted to a size for bonding with an image display device.

A double-sided adhesive optical film formed into a size larger than an optical film for bonding with an image display device can also be cut into a specific size using a Thompson knife, a round knife, a disc knife, a laser cutter, etc. A double-sided adhesive optical film having a non-contact area 2x around the optical film can also be produced by providing an area on the optical film where the first adhesive layer is not provided and cutting on the area. For example, when a long strip of double-sided adhesive optical film is cut into a specific size, as long as the area on the optical film where the first adhesive layer is not provided is cut, a double-sided adhesive optical film having a non-contact area along the cutting line can be obtained. Multiple films can be cut from a large-sized single film (mother substrate), and films of specific sizes can be further cut to produce optical films with double-sided adhesives on the periphery with non-bonding areas.

In the non-bonded area 2x, the protective sheet 41 preferably covers the first main surface of the adhesive layer 21. The end surface 41e of the protective sheet 41 may be aligned with the end surface 21e of the adhesive layer 21, or may be aligned with the end surface 11e of the optical film 11. The end surface 41e of the protective sheet 41 may be located between the end surface 21e of the adhesive layer 21 and the end surface 11e of the optical film 11, or may be located further outward than the end surface 11e of the optical film 11.

If an area without the first adhesive layer is provided on the optical film, and the area with the adhesive layer and the area without the adhesive layer are covered by the protective sheet, the optical film 11 and the end surface 41e of the protective sheet 41 are aligned in both the contact area and the non-contact area as shown in FIG2. In the non-contact area 2x, as long as the end surface 21e of the adhesive layer 21 is located further inward than the end surface 11e of the optical film 11 and the end surface 41e of the protective sheet 41, the adhesive contamination or adhesive defect of the end surface 21e of the adhesive layer can be suppressed.

The contact area around the optical film can be formed by attaching the first adhesive layer to the surface of the optical film without exposing the main surface of the optical film. In the contact area, the end surface of the protective sheet 41 can be aligned with the end surface of the first adhesive layer 21, or the end surface of the protective sheet 41 can be located further outward than the end surface of the first adhesive layer 21.

As shown in FIG3 , in the optical film 53 with double-sided adhesive, the end surface 21c in the center of the thickness direction of the first adhesive layer 21 is located inside the end surface of the optical film 11 and the end surface of the first protective sheet 41. In the bonding area, the end surface 21c in the center of the thickness direction of the adhesive layer 21 is located inside the end surface of the optical film 11, so that the paste contamination or paste defect during the transportation of the optical film with double-sided adhesive or on the production line of the bonding process can be suppressed.

For example, by cutting the optical film with double-sided adhesive while applying pressure from the main surface, the position of the end surface of the adhesive layer at the interface with the optical film is consistent with the position of the end surface of the optical film, and the end surface of the adhesive layer can be located inside in the center of the thickness direction of the adhesive layer. If the optical film with double-sided adhesive is pressurized while the protective sheets 41 and 42 are attached to the adhesive layers 21 and 22, the adhesive layer is elastically deformed, and the end of the adhesive layer protrudes from the end of the optical film in the center of the thickness direction. If the adhesive layers 21, 22 are cut together with the optical film 11 and the protective sheets 41, 42 in this state, the end faces of the optical film 11 and the protective sheets 41, 42 are aligned with the end faces of the adhesive layers 21, 22. If the pressure is released after cutting, the end face of the center of the thickness direction of the adhesive layer retreats to the inner side of the end face of the optical film 11 due to the deformation of the adhesive, and a double-sided adhesive optical film is obtained, in which the end face of the center of the thickness direction of the adhesive layer is located on the inner side as shown in FIG. 3.

When the end face of the center portion of the first adhesive layer 21 in the thickness direction is located further inward than the end face of the optical film 11 in the bonding area, the distance _W2 between the end face of the optical film 11 and the end face of the center portion of the thickness direction of the first adhesive layer is, for example, about 5 μm to 300 μm. From the perspective of both suppressing the extension of the adhesive from the end face and the bonding of the end, _W2 is more preferably about 10 μm to 100 μm, and further preferably about 15 μm to 70 μm. _W2 and _W1 may be the same or different. Generally, _W2 < _W1 .

The double-sided adhesive optical film 51 shown in FIG. 1 is provided with a non-contact area 2x along one short side 11a ₁ of the four sides of the rectangular optical film 11. The non-contact area can be provided on more than two sides of the rectangle, or on the long side of the rectangle. In the non-contact area, the end face of the first adhesive layer does not need to extend parallel to the side of the optical film. For example, the non-contact area may also have a portion whose width decreases from the end of the side of the rectangle (the vertex of the rectangle) toward the center of the side. The non-contact area does not need to be provided along the entire length of the side. For example, the non-contact area may be provided only on a portion of the side of the rectangle or on the vertex of the rectangle.

The shape of the optical film is not limited to a rectangle, and can be an appropriate shape according to the shape or size of the screen of the image display device. For example, the top view shape of the optical film can also be a triangle, rhombus, parallelogram, trapezoid, pentagon, hexagon or other polygon, circle, ellipse, star, etc.

<Image display device> FIG. 4 is a cross-sectional view of an image display device 101 made using an optical film 51 with a double-sided adhesive. In the image display device 101, an optical film 11 is arranged on an image display unit 60, and a cover glass 71 with a touch sensor is provided on the viewing side of the optical film 11. The optical film 11 and the image display unit 60 are bonded via a second adhesive layer 22, and the optical film 11 and the cover glass 71 are bonded via a first adhesive layer 21. The image display unit 60 is, for example, a liquid crystal unit, an organic EL (OLED), or a micro LED (Light Emitting Diode). A transparent resin sheet containing a transparent resin material such as acrylic resin may also be used instead of the cover glass 71.

Near the end of the cover glass 71, a flexible printed circuit board (FPC) 91 as an electrical connection member is connected to a touch sensor (not shown) provided on the surface opposite to the optical film 11. The FPC 91 is bent so as to be routed to the back side of the image display unit 60.

Fig. 5 is a cross-sectional view of an image display device 501 using a conventional double-sided adhesive optical film 551. The image display device 501 has a similar structure to the image display device 101 of Fig. 4, but the adhesive layer 521 between the optical film 11 and the cover glass 571 is disposed on the entire surface of the optical film.

In the image display device 501, along the entire periphery of the optical film 11, the end surface 11e is aligned with the end surface 521e of the adhesive layer 521, and the space between the optical film 11 and the cover glass 571 is entirely covered by the adhesive layer 521. Since there is no gap between the optical film 11 and the cover glass 571, the contact 507a of the touch sensor and the FPC 591 is arranged on the outer side of the end surface 11e of the optical film 11. Since the space for accommodating the electrical connection components such as the FPC must be ensured outside the display area of the screen, it is difficult to reduce the width of the frame area around the screen.

On the other hand, in the image display device 101 of FIG. 4 using the optical film 51 with double-sided adhesive of the present invention, by arranging FPC 91 in the space of the non-contact area 2x along the edge 11a ₁ , the contact point 7a between the touch sensor and FPC 91 can be set on the end surface 11e of the optical film 11 or further inside the end surface 11e. In this way, the non-contact area 2x without the first adhesive layer 21 is set on the optical film 11, and the FPC is arranged in the gap portion, so that the periphery of the screen and the space near it are effectively utilized, thereby achieving a narrow edge.

As described above, in the contact area around the optical film, the end surface 21c of the center portion in the thickness direction of the first adhesive layer 21 is located further inward than the end surface of the optical film 11 (see FIG. 3 ). In this form, even when the distance _W2 between the end surface 21c of the first adhesive layer 21 and the end surface of the optical film in the contact area is large, the positions of the end surface of the first adhesive layer and the end surfaces of the optical film 11 and the protective sheet 41 are consistent at the attachment interface of the optical film 11 and the attachment interface of the protective sheet 41. Therefore, even when _W2 is large, it is difficult to avoid physical interference between the FPC and the adhesive layer in the contact area and seek to narrow the edge.

The use form of the optical film 51 with a double-sided adhesive having a non-contact area on one side is not limited to the structure shown in FIG. 4, and can also be applied to image display devices having other structures. For example, as shown in FIG. 6, the cover glass 72 disposed on the surface can be provided with a decorative print 72a on the periphery of the screen on the surface opposite to the optical film 11. In this embodiment, the FPC 91 is arranged in the space of the non-contact area 2x further outside the decorative print 72a of the cover glass 71, and the contact point 7a between the touch sensor and the FPC is set.

As in the image display device 103 shown in FIG. 7 , the optical film 11 and the touch sensor 73 may be bonded together via a first adhesive layer 21 , and a cover glass 79 may be bonded thereon via another adhesive layer 29 .

In the image display device, the first adhesive layer 21 side of the double-sided adhesive optical film does not need to be arranged on the viewing side, but the first adhesive layer 21 can also be arranged on the image display unit side. For example, in the image display device 104 shown in FIG8, a polarizing plate 17 having a touch sensor is attached to the image display unit 60 via the first adhesive layer 21, and a cover glass 79 is attached to the polarizing plate 17 via the second adhesive layer 22. Near the end of the polarizing plate 17 as an optical film, an FPC 91 is connected to the touch sensor provided on the surface opposite to the image display unit 60. In this embodiment, the space can be effectively utilized by setting the area between the image display unit 60 and the polarizing plate 17 as an optical film, where the FPC contact 7a is provided, as the non-contact area 2x.

<Variations of the First Embodiment> As described above, the location of the non-contact area on the first main surface of the optical film is not limited to the short side of the rectangle. For example, as shown in FIG. 9 , the double-sided adhesive optical film 56 may have a non-contact area 2x of the first main surface that exposes the optical film 11 on the two long sides 11a ₂ and 11a ₄ of the rectangle.

FIG. 10 is a schematic three-dimensional diagram of an image display device 106 made using the optical film 56 with double-sided adhesive of FIG. 9. The image display device 106 has a cover glass 74 on the viewing side surface, and the end of the cover glass 74 is combined with the housing 84. The long side 74a of the cover glass 74 extending in the x direction is curved. As long as the curved surface portion 74a of the cover glass 74 is arranged in a manner to be located on the non-contact area 2x of the optical film with double-sided adhesive, physical interference between the first adhesive layer 21 and the cover glass 74 can be avoided, and the space in the device can be effectively utilized.

In FIG. 10 , the long side 74a of the cover glass 74 has a shape that is chamfered into a curved surface, but the long side of the cover glass may also be chamfered into a flat surface. In addition, the top portion of the cover glass may be chamfered into a flat surface or a curved surface. The shape of the outer surface and the inner surface of the chamfered portion of the cover glass or the front surface transparent plate or the housing may be the same or different. In addition, the housing may be arranged in a non-contact area to avoid physical interference between the adhesive layer and the housing.

Figures 11 and 12 are top views of the first main surface side of the optical film with double-sided adhesive of other embodiments. The optical film with double-sided adhesive 57A shown in Figure 11 has a non-contact area _2x1 with a curvature at the four vertices of the rectangle. For example, if the optical film with double-sided adhesive 57A is used in an image display device having a front surface transparent plate or a housing with a rectangular shape with a curvature at the vertices, the physical interference between the curved surface portion near the vertices of the display area and the first adhesive layer 21 can be avoided, and the space in the device can be effectively utilized.

The optical film 57B with double-sided adhesive shown in FIG12 has a non-contact area _2x1 with a radius at both ends of a short side _11a3 , and has a non-contact area _2x2 along the entire length of another short side _11a1 . As shown in FIG12, the non-contact area _2x2 arranged along the short side _11a1 can also be a straight line along the entire length of the short side _11a1 , and the corners are not radiused. In this way, the non-contact area arranged along the edge can be used to avoid physical interference with the front surface transparent component or the housing, and can also be used to avoid physical interference with the component components such as FPC.

Fig. 13 is a top view of the first main surface of a double-sided adhesive optical film 58 having a non-contact area on a portion of the edge. The double-sided adhesive optical film 58 has a cut-out non-contact area 2x ₃ on a short side 11a ₁ of a rectangle.

FIG. 14 is a cross-sectional view of an image display device 108 made using an optical film 58 with a double-sided adhesive. In the image display device 108, a wire 98 is provided to ground the image display unit 60 and the optical film 11. In the non-contact area _2x3 , the first adhesive layer 21 is not provided on the optical film 11 and the optical film 11 is exposed, so a grounding point 8a of the wire 98 can be provided on the first main surface of the optical film 11. The wire 98 can be formed by a metal wire or a metal paste. In order to prevent oxidation of the metal constituting the wire 98, an insulating layer such as a resin coating layer can be provided on the surface of the wire.

As examples of components of an image display device disposed in a non-contact area on the first main surface of an optical film, examples of a contact point with an FPC disposed in the non-contact area, an example of a front surface transparent plate or a housing disposed in the non-contact area, and an example of a contact point with a wire are shown, but the configuration of the image display device is not limited to these, and the components disposed in the non-contact area are not particularly limited. The components disposed in the non-contact area can be any conductive material or insulating material. For example, a conductive material or a resin material can also be disposed in a manner that covers the non-contact area on the first main surface of the optical film and the side surface of the optical film.

The conductive material or resin material can also be provided in a manner that further covers the surface of the image display panel. For example, by providing a resin layer in a manner that covers the surface of the organic EL unit and the side surface of the optical film to seal the organic EL unit, the degradation of the organic EL can be suppressed.

The image display unit does not need to be flat. For example, the entire surface of the image display unit can be curved, or the end of the image display unit can be curved. In the case where the end of the image display unit is curved, the non-contact area can also be included in the curved portion. The conductive material or resin material can also be provided in a manner covering the surface of the image display panel. In addition, the image display unit can also be curved in the non-display portion such as the connection area with the FPC.

In the optical film with double-sided adhesive, the second adhesive layer 22 can also be provided in a manner to cover the entire second main surface of the optical film. By having no non-contact area along the entire periphery of the second main surface, the image display unit 60 and the optical film 11 can be surely attached to prevent peeling from the end. In addition to providing a non-contact area on the first main surface of the optical film, a non-contact area can also be provided on the second main surface to avoid physical interference with the components of the image display device.

[Second embodiment] The optical film with double-sided adhesive of the second embodiment has an area (non-contact area) along the entire periphery of the first main surface of the optical film where the first adhesive layer is not attached and the optical film is exposed. In this embodiment, the non-contact area may also have areas of different widths along the periphery of the first main surface of the optical film. The optical film with double-sided adhesive of the second embodiment has a non-contact area along the entire periphery of the first main surface of the optical film 11, and there is no contact area around the first main surface of the optical film 11. Except for this, the structure of the optical film with double-sided adhesive of the second embodiment is the same as that of the first embodiment.

An example of a double-sided adhesive optical film of the second embodiment is shown in FIG15. FIG15A is a top view of the first main surface side of the double-sided adhesive optical film 251, and FIG15B is a cross-sectional view along the B1-B2 line. The double-sided adhesive optical film of the second embodiment is similar to the first embodiment in that a first adhesive layer 21 is provided on one side of the optical film 11 and a second adhesive layer 22 is provided on the other side. A protective sheet (not shown) may also be temporarily adhered to the surfaces of the adhesive layers 21 and 22.

The width _W11 of the non-contact area _2x41 along one short side _11a1 of the optical film 251 with double-sided adhesive is different from the width _W13 of the non-contact area _2x43 along the other short side _11a3 . For example, when forming an image display device, the space of the non-contact area _2x41 becomes an area for connecting the FPC to the touch sensor, and the space of the non-contact area _2x43 becomes an area for avoiding physical interference with the cover glass or the housing with a curved end. The non-contact area along the rectangular long side _11a2 and the long side _11a4 of the optical film 11 also becomes an area for avoiding physical interference with the cover glass or the housing. In this way, by adjusting the width of the non-bonding area according to the object to avoid physical interference, both effective use of space and bonding reliability through the first adhesive layer can be taken into account.

The ratio of the maximum value to the minimum value of the width of the non-contiguous region is not particularly limited. The maximum value of the width of the non-contiguous region is, for example, 1.1 times or more of the minimum value of the width of the non-contiguous region. The maximum value of the width of the non-contiguous region may also be 1.3 times or more of the minimum value of the width of the non-contiguous region, or 1.5 times or more, or 2 times or more, or 3 times or more.

FIG. 16 is a top view of the first main surface side of the optical film 253 with double-sided adhesive. In the optical film 253 with double-sided adhesive, the width of the non-contact area 2x ₅ is roughly equal in the central part of the rectangular side. Near the vertex of the rectangle, the non-contact area 2x ₅ becomes a curved plane shape, and the width of the non-contact area decreases from the end of the rectangular side toward the central side. If the optical film 253 with double-sided adhesive having such a non-contact area 2x ₅ is used, physical interference with image display device components such as cover glass or housing can be avoided along the entire periphery of the display area.

[Third embodiment] The non-contact area of the optical film with double-sided adhesive can also be set in an area other than the periphery of the optical film. The optical film with double-sided adhesive of the third embodiment has an area (non-contact area) on the inner side of the periphery of the first main surface of the optical film where the first adhesive layer is not attached and the optical film is exposed. Other than this, the structure of the optical film with double-sided adhesive of the third embodiment is the same as that of the first and second embodiments. The optical film with double-sided adhesive of the third embodiment can also temporarily adhere a protective sheet (not shown) to the surface of the adhesive layer 21, 22 in the same manner as the first and second embodiments.

An example of a double-sided adhesive optical film of the third embodiment is shown in FIG17 . FIG17 is a top view of the first main surface side of the double-sided adhesive optical film 351. FIG18 is a yz cross-sectional view (a cross-sectional view along the short side direction of FIG17 ) of an image display device 109 made using the double-sided adhesive optical film 351.

The optical film 351 with double-sided adhesive has a non-contact area _2x6 extending parallel to the long side on the inner side of the long side _11a4 . In the image display device 109, the optical film 11 is arranged on the image display unit 60, and the cover glass 372 is provided on the viewing side of the optical film 11. The optical film 11 and the image display unit 60 are bonded via the second adhesive layer 22, and the optical film 11 and the cover glass 372 are bonded via the first adhesive layer 21. On the cover glass 372, decorative printing is applied to the surface opposite to the optical film 11, and the raised portion 372a generated by the decorative printing is arranged in a manner of overlapping _2x6 on the non-contact area of the optical film 351 with double-sided adhesive.

In the image display device 109, no adhesive layer is provided directly below the raised portion 372a generated by decorative printing, and there is no compression deformation of the adhesive caused by the raised portion. Therefore, it is possible to suppress the peeling of the adhesive from the raised portion or the display unevenness caused by the compression stress of the adhesive.

The double-sided adhesive optical film of FIG17 also corresponds to the first embodiment because it has non-contact areas _2x6 on the short sides _11a1 and _11a3 of the rectangle. As shown in FIG19 as a top view of a double-sided adhesive optical film 352, the double-sided adhesive optical film of the third embodiment does not have a non-contact area around the optical film 11, but only has a non-contact area _2x7 on the inner side of the periphery.

The optical film with double-sided adhesive may also have non-contact areas along the periphery of the first main surface of the optical film and the area inside the periphery. For example, as shown in the top view in FIG. 20 , the optical film 353 with double-sided adhesive may have non-contact areas 2x along the short side 11a ₁ of the rectangle and non-contact areas 2x ₆ inside the long side 11a ₄ .

The non-contact area existing at the periphery of the first main surface and the non-contact area existing at the inner side of the periphery may be connected to form a whole, or they may not be connected. For example, as shown in the top view of the double-sided adhesive optical film 355 in FIG. 21, there may be a non-contact area _2x8 extending parallel to one side _11a1 of the rectangle, and a non-contact area _2x1 disposed near the vertices of both ends of the side _11a3 .

As described above, the optical film with double-sided adhesive of the present invention has adhesive layers on both sides of the optical film, and has an area on at least one side where the adhesive layer is not provided and the optical film is exposed. Due to the existence of the non-contact area, a gap is formed between the optical film and the adherend when the image display device is formed. By arranging the components of the image display device in the space, physical interference with the adhesive can be avoided, and the space can be effectively utilized, which is conducive to space saving and narrow edge of the image display device.

2x: non-contact area 2x ₁ : non-contact area 2x ₂ : non-contact area 2x ₃ : non-contact area 2x ₅ : non-contact area 2x ₆ : non-contact area 2x ₇ : non-contact area 2x ₈ : non-contact area 2x ₄₁ : non-contact area 2x ₄₃ : non-contact area 7a: contact point 8a: ground point 11: optical film 11a ₁ : side 11a ₂ : side 11a ₃ : side 11a ₄ : side 11e: end face 17: polarizing plate 21: adhesive layer 21c: end face 21e: end face 22: adhesive layer 29: adhesive layer 41: protective sheet 41e: end face 42: protective sheet 51: optical film with adhesive 53: optical film with adhesive 56: optical film with adhesive 57A: optical film with adhesive 57B: optical film with adhesive 58: optical film with adhesive 60: image display unit 71: cover glass with touch sensor 72: cover glass with touch sensor 72a: raised part (printing part) 73: Touch sensor 74: Cover glass 74a: Long side 79: Cover glass 84: Housing 91: Flexible printed wiring board 98: Lead wire 101: Image display device 102: Image display device 103: Image display device 104: Image display device 106: Image display device 108: Image display device 109: Image display device 251: Optical film with adhesive 253: Optical film with adhesive 351: Optical film with adhesive 352: Optical film with adhesive 353: Optical film with adhesive 355: Optical film with adhesive 372: Cover glass with touch sensor 372a: Raised part (printed part) 451: Optical film with adhesive 501: Image display device 507a: Contact 521: Adhesive layer 521e: End surface 551: Optical film with adhesive 571: Cover glass 591: Flexible printed wiring board W ₁ : Width W ₂ : Distance W ₁₁ : Width W ₁₃ : Width

FIG. 1A is a top view of an optical film with a double-sided adhesive, and FIG. 1B is a cross-sectional view of an optical film with a double-sided adhesive. FIG. 2 is a cross-sectional view of an optical film with a double-sided adhesive having a protective sheet disposed on an adhesive sheet. FIG. 3 is a cross-sectional view of an optical film with a double-sided adhesive having a protective sheet disposed on an adhesive sheet. FIG. 4 is a cross-sectional view of an image display device. FIG. 5 is a cross-sectional view of an image display device of the prior art. FIG. 6 is a cross-sectional view of an image display device. FIG. 7 is a cross-sectional view of an image display device. FIG. 8 is a cross-sectional view of an image display device. FIG. 9 is a top view of an optical film with a double-sided adhesive. FIG. 10 is a schematic three-dimensional diagram of an image display device. FIG. 11 is a top view of an optical film with a double-sided adhesive. FIG. 12 is a top view of an optical film with a double-sided adhesive. FIG. 13 is a top view of an optical film with a double-sided adhesive. FIG. 14 is a cross-sectional view of an image display device. FIG. 15A is a top view of an optical film with a double-sided adhesive, and FIG. 15B is a cross-sectional view of an optical film with a double-sided adhesive. FIG. 16 is a top view of an optical film with a double-sided adhesive. FIG. 17 is a top view of an optical film with a double-sided adhesive. FIG. 18 is a cross-sectional view of an image display device. Figure 19 is a top view of an optical film with a double-sided adhesive. Figure 20 is a top view of an optical film with a double-sided adhesive. Figure 21 is a top view of an optical film with a double-sided adhesive.

2x: Non-contiguous area

7a: Contact

11: Optical film

21: Adhesive layer

22: Adhesive layer

51: Optical film with adhesive

60: Image display unit

71: Cover glass with touch sensor

91: Flexible printed wiring board

101: Image display device

Claims (15)

An optical film with double-sided adhesive, comprising: an optical film having a first main surface and a second main surface, a first adhesive layer disposed on the first main surface of the optical film, and a second adhesive layer disposed on the second main surface of the optical film, wherein the optical film is rectangular, and has a non-contact area along the periphery of the first main surface of the optical film where the first adhesive layer is not disposed and the optical film is exposed, and a contact area where the first adhesive layer is attached to the optical film, and the non-contact area has a distance of more than 10 μm from the end surface of the optical film to the end surface of the first adhesive layer along at least one side of the rectangle, and the contact area has the entire length of at least one side of the rectangle. As in claim 1, the optical film with double-sided adhesive, wherein the non-contact area has a portion whose width decreases from the end of the side of the rectangle toward the center. An optical film with double-sided adhesive, comprising: an optical film having a first main surface and a second main surface, a first adhesive layer disposed on the first main surface of the optical film, and a second adhesive layer disposed on the second main surface of the optical film, wherein the optical film is rectangular, and has a non-contact area along the periphery of the first main surface of the optical film where the first adhesive layer is not disposed and the optical film is exposed, and a contact area where the first adhesive layer is attached to the optical film, and the non-contact area has a portion having a distance of more than 10 μm from the end surface of the optical film to the end surface of the first adhesive layer, and has a portion whose width decreases from the end of the side of the rectangle toward the center. A double-sided adhesive optical film as claimed in any one of claims 1 to 3, wherein in the above-mentioned bonding area, with respect to the above-mentioned first adhesive layer, at the interface with the above-mentioned optical film, the position of the end face of the above-mentioned first adhesive layer is consistent with the position of the end face of the above-mentioned optical film, and in the central part of the thickness direction of the above-mentioned first adhesive layer, the end face of the above-mentioned first adhesive layer is located more inward than the end face of the above-mentioned optical film. A double-sided adhesive optical film, comprising: an optical film having a first main surface and a second main surface, a first adhesive layer disposed on the first main surface of the optical film, and a second adhesive layer disposed on the second main surface of the optical film, wherein the optical film is rectangular, and has a non-contact area along the entire periphery of the first main surface of the optical film where the first adhesive layer is not disposed and the optical film is exposed, and the non-contact area has a portion having a distance of more than 10 μm from the end surface of the optical film to the end surface of the first adhesive layer, and has a portion whose width decreases from the end of the side of the rectangle toward the center. As in claim 5, the optical film with double-sided adhesive, wherein the width of the non-contacted area in one side of the rectangle is different from the width of the non-contacted area in the other side of the rectangle. A double-sided adhesive optical film as claimed in any one of claims 1 to 3, 5 and 6, wherein in the non-contact area, the end surface of the optical film and the end surface of the first adhesive layer have a portion extending parallel to the periphery of the optical film. A double-sided adhesive optical film as claimed in any one of claims 1 to 3, 5 and 6, wherein the second adhesive layer is provided along the entire periphery of the second main surface of the optical film, and there is no area where the second main surface of the optical film is exposed. An optical film with a double-sided adhesive, comprising: an optical film having a first main surface and a second main surface, a first adhesive layer disposed on the first main surface of the optical film, and a second adhesive layer disposed on the second main surface of the optical film, a non-contact area along the entire periphery of the first main surface of the optical film where the first adhesive layer is not disposed and the optical film is exposed, and a non-contact area along the entire periphery of the first main surface of the optical film where the first adhesive layer is not disposed and the optical film is exposed. The periphery of the first main surface of the optical film has the non-contact area with a distance of more than 10 μm from the end surface of the optical film to the end surface of the first adhesive layer, and has areas with different widths of the non-contact area, and the second adhesive layer is provided along the entire periphery of the second main surface of the optical film, and there is no area where the second main surface of the optical film is exposed. As in claim 9, the optical film with double-sided adhesive is rectangular, and the width of the non-contacted area in one side of the rectangle is different from the width of the non-contacted area in the other side of the rectangle. As in claim 9 or 10, the optical film with double-sided adhesive, wherein in the non-contact area, the end surface of the optical film and the end surface of the first adhesive layer have a portion extending parallel to the periphery of the optical film. An optical film with double-sided adhesive, comprising: an optical film having a first main surface and a second main surface, a first adhesive layer disposed on the first main surface of the optical film, and a second adhesive layer disposed on the second main surface of the optical film, wherein a non-contact area is provided on the inner side of the periphery of the first main surface of the optical film where the first adhesive layer is not provided and the optical film is exposed, the non-contact area having a portion with a width of 10 μm or more, and the second adhesive layer is provided along the entire periphery of the second main surface of the optical film, and there is no area where the second main surface of the optical film is exposed. An optical film with a double-sided adhesive as claimed in any one of claims 1 to 3, 5, 6, 9, 10 and 12, wherein the optical film comprises a polarizing plate. A double-sided adhesive optical film as claimed in any one of claims 1 to 3, 5, 6, 9, 10 and 12, wherein a first protective sheet is releasably attached to the first adhesive layer, and a second protective sheet is releasably attached to the second adhesive layer. As in claim 14, the optical film with double-sided adhesive, wherein the end surface of the optical film is aligned with the end surface of the first protective sheet along the entire periphery of the optical film.