Optical sheet, polarizing plate with optical sheet, touch panel with optical sheet and display device

Abstract

To provide an optical sheet which appropriately suppresses malfunctioning of a touch panel when incorporated in a display device together with the touch panel.SOLUTION: An optical sheet 1 provided herein comprises a base material 11 and an optical functional layer 12 bonded to the base material 11. The optical functional layer 12 comprises light absorptive sections 12a and a light transmissive section 12b. A relative permittivity of the optical sheet 1 measured in compliance with JIS C 2138:2007 at 25°C is set to be in a range of 3.18 to 3.51, inclusive, in a frequency range of 1 KHz to 1 MHz, inclusive.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an optical sheet that imparts an optical effect to image light formed by a display panel, and more particularly to a polarizing plate with the optical sheet, a touch panel with the optical sheet, and a display device that include the optical sheet. [Background technology]

[0002] 2. Description of the Related Art Optical sheets that are installed on display panels such as liquid crystal display panels and organic LED (Organic Light Emitting Diode) panels and impart optical effects to image light formed by the display panel have been conventionally known.

[0003] For example, a louver film as an optical sheet is disclosed in Patent Document 1. This louver film includes an optical functional layer in which light absorbing portions and light transmitting portions are arranged alternately.

[0004] The louver film is used to prevent the image light from the display panel from spreading over a wide area, and is used to provide a function for preventing peeping.

[0005] On the other hand, Patent Document 2 discloses a display device including an organic LED panel and a touch panel. Patent Document 2 proposes bonding multiple members constituting the display device with an adhesive having a low relative dielectric constant, thereby suppressing malfunction of the touch panel. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2017-45060 A [Patent Document 2] International Publication No. 2019 / 049726 Summary of the Invention [Problem to be solved by the invention]

[0007] Incidentally, louver films are sometimes incorporated into display devices with touch panels. In this case, if the dielectric constant of the louver film is high, the touch panel is likely to malfunction due to the influence of driving noise generated in the display panel. However, optical sheets such as louver films usually have a multi-layer structure, which makes it difficult to adjust the dielectric constant. In addition, the light absorbing portion of the louver film may contain a component that can increase the dielectric constant, which makes it even more difficult to adjust the dielectric constant.

[0008] The present invention has been made in consideration of the above-mentioned circumstances, and has an object to provide an optical sheet, a polarizing plate with an optical sheet, a touch panel with an optical sheet, and a display device that can effectively suppress malfunction of a touch panel. [Means for solving the problem]

[0009] The optical sheet according to the present invention comprises a substrate and an optical functional layer bonded to the substrate, the optical functional layer having a light absorbing portion and a light transmitting portion, and has a relative dielectric constant at 25°C of 3.18 or more and 3.51 or less in the frequency range of 1 KHz or more and 1 MHz or less, which conforms to JIS C 2138:2007.

[0010] The optical sheet according to the present invention may further include a first ultraviolet curing resin layer provided on the surface of the optical functional layer opposite to the substrate side.

[0011] The optical sheet according to the present invention may further include a second ultraviolet curing resin layer provided on the surface of the base opposite to the optical functional layer.

[0012] One of the outermost surfaces of the optical sheet may be formed by the first ultraviolet curable resin layer, and the other of the outermost surfaces of the optical sheet may be formed by a surface of the base opposite to the optical functional layer side. In this case, the thickness of the optical sheet may be 100 μm or more and 500 μm or less, and preferably 250 μm or more and 300 μm or less.

[0013] In addition, one of the outermost surfaces of the optical sheet may be formed by the first ultraviolet curing resin layer, and the other of the outermost surfaces of the optical sheet may be formed by the second ultraviolet curing resin layer, and the thickness of the base material may be 50 μm or more. The thickness of the base material is preferably 130 μm or more.

[0014] In addition, one of the outermost surfaces of the optical sheet may be formed by a surface of the optical functional layer opposite to the substrate side, and the other of the outermost surfaces of the optical sheet may be formed by a surface of the substrate opposite to the optical functional layer side, and the thickness of the optical sheet may be 500 μm or less and the thickness of the substrate may be 50 μm or more. It is preferable that the thickness of the optical sheet is 220 μm or less and the thickness of the substrate is 50 μm or more.

[0015] In addition, the optical functional layer may further have a land portion that is integrated with the light-transmitting portions and spans a plurality of the light-transmitting portions, and is made of the same material as the light-transmitting portions, and the light-absorbing portions are exposed from one of a pair of main surfaces of the optical functional layer, and the land portion forms the other of the pair of main surfaces and is joined to the substrate, and covers the light-absorbing portions from the substrate side.

[0016] The light absorbing portion may include a base resin and light absorbing particles held by the base resin, and the light absorbing particles may include carbon black. In this case, the light absorbing particles may be contained in an amount of 10 parts by weight or more and 30 parts by weight or less relative to 100 parts by weight of the light absorbing portion, and the carbon black may be contained in an amount of 10 parts by weight or more and 50 parts by weight or less relative to 100 parts by weight of the light absorbing particles.

[0017] Another optical sheet according to the present invention is an optical sheet comprising a substrate and an optical functional layer bonded to the substrate, the optical functional layer having a light absorbing portion and a light transmitting portion, and having a dielectric tangent at 25°C of 0.0102 or more and 0.0197 or less in the frequency range of 1 KHz or more and 1 MHz or less, in accordance with JIS C 2138:2007.

[0018] A polarizing plate with an optical sheet according to the present invention includes a polarizing plate and the optical sheet.

[0019] Moreover, a touch panel with an optical sheet according to the present invention includes a touch panel and the optical sheet provided on the touch panel.

[0020] A display device according to the present invention includes a display panel and the optical sheet provided on the display panel. Effect of the Invention

[0021] According to the present invention, malfunction of a touch panel can be suitably suppressed. [Brief description of the drawings]

[0022] [Figure 1] 1 is a schematic cross-sectional view showing a layer structure of a display device including an optical sheet according to a first embodiment of the present invention. [Diagram 2] 1 is a schematic cross-sectional view showing a layer structure of an optical sheet according to a first embodiment. [Diagram 3] FIG. 11 is a schematic cross-sectional view showing a layer structure of an optical sheet according to a second embodiment. [Figure 4] FIG. 11 is a schematic cross-sectional view showing a layer structure of an optical sheet according to a third embodiment. [Diagram 5] 1. FIG. 4 is a diagram showing a modification of the display device shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Hereinafter, optical sheets and the like according to each embodiment of the present invention will be described with reference to the drawings. In the drawings attached to this specification, the scale and aspect ratios, etc. are appropriately changed and exaggerated from those of the actual objects for the convenience of illustration and understanding.

[0024] In addition, in this specification, the terms "plate," "sheet," and "film" are not distinguished from one another solely on the basis of differences in name. For example, an "optical sheet" is a concept that includes members that can be called plates and films, and therefore an "optical sheet" cannot be distinguished from members called "optical films" or the like solely on the basis of differences in name.

[0025] Furthermore, the term "sheet surface (plate surface, film surface)" refers to a surface that coincides with the planar direction of the target sheet-like (plate-like, film-like) member when the target sheet-like (plate-like, film-like) member is viewed overall and in a global perspective. Furthermore, the normal to the sheet surface means a line perpendicular to the sheet surface, and the direction parallel to the normal is called the normal direction. Furthermore, in the following description, the sheet surface (plate surface, film surface) may also be called the main surface.

[0026] In addition, terms used in this specification that specify shapes, geometric conditions, and the extent thereof, such as "parallel," "orthogonal," and "same," as well as values ​​of length and angle, are not to be bound by strict meanings, but are to be interpreted to include a range within which similar functions can be expected.

[0027] <<First embodiment>> Fig. 1 is a schematic cross-sectional view showing a layer structure of a display device DP including an optical sheet 1 according to a first embodiment. The display device DP shown in Fig. 1 is configured by laminating an organic LED (Organic Light Emitting Diode) panel 15, the optical sheet 1, a circular polarizer 20, a touch panel 30, and a cover glass 40 in this order.

[0028] The optical sheet 1 is disposed on a display surface (front surface) 15A of the organic LED panel 15. The front surface of the optical sheet 1 and the rear surface of the circular polarizer 20 are bonded together with an adhesive layer, the front surface of the circular polarizer 20 and the rear surface of the touch panel 30 are bonded together with an adhesive layer, and the front surface of the touch panel 30 and the rear surface of the cover glass 40 are bonded together with an adhesive layer.

[0029] Each of the adhesive layers is a so-called OCA (Optical Clear Adhesive) and has high light transmittance. In this example, the organic LED panel 15 and the optical sheet 1 are not bonded together with an adhesive layer, but they may be bonded together with an adhesive layer.

[0030] The circular polarizing plate 20 has a polarizer and a retardation plate, the retardation plate is disposed on the organic LED panel 15 side, and the polarizer is bonded to the surface of the retardation plate opposite to the organic LED panel 15. Specifically, the polarizer is a linear polarizer, and the retardation plate is a λ / 4 retardation plate.

[0031] The touch panel 30 includes a transparent substrate and employs a capacitive touch panel. The touch panel 30 may include a transparent glass plate as the transparent substrate and transparent sensor electrodes arranged on the glass plate in, for example, a mosaic pattern. The cover glass 40 has a protective function, but may also have other functions such as an anti-reflection function.

[0032] Incidentally, in the illustrated example, when the circular polarizer 20 is disposed on the external light incident side (the cover glass 40 side) of the optical sheet 1, when external light is incident from the cover glass 40 toward the organic LED panel 15, the circular polarizer 20 makes it difficult for the external light to reach the optical sheet 1. This can suppress, for example, multiple reflections within the optical sheet 1. As a result, the occurrence of visibility-impairing phenomena such as rainbow unevenness and interference fringes is suppressed, and good visibility of the image can be ensured.

[0033] Before the display device DP is assembled, the optical sheet 1 and the circular polarizer 20 may be integrated together to form a polarizer with an optical sheet, and the optical sheet 1 and the touch panel 30 may be integrated together to form a touch panel with an optical sheet.

[0034] <Optical sheet> The optical sheet 1 will be described in detail below with reference to Fig. 2. The optical sheet 1 shown in Fig. 2 includes a substrate 11, an optical functional layer 12, and a first ultraviolet cured resin layer 13. The substrate 11 and the optical functional layer 12 are bonded to each other, and the first ultraviolet cured resin layer 13 covers the optical functional layer 12 from the side opposite the substrate 11 side.

[0035] The image light from the organic LED panel 15 enters through the first ultraviolet curing resin layer 13 and exits from the substrate 11. The optical function layer 12 has a light absorbing portion 12a and a light transmitting portion 12b. The optical function layer 12 adjusts, for example, the orientation of the image light by absorbing or reflecting a part of the image light from the organic LED panel 15 at the light absorbing portion 12a.

[0036] The optical sheet 1 is configured so that the relative dielectric constant at 25°C conforming to JIS C 2138:2007 is 3.18 or more and 3.51 or less in the frequency range of 1 KHz or more and 1 MHz or less, and / or the dielectric tangent at 25°C conforming to JIS C 2138:2007 is 0.0102 or more and 0.0197 or less in the frequency range of 1 KHz or more and 1 MHz or less.

[0037] As described above, when the optical sheet 1 has a relative dielectric constant of 3.18 or more and 3.51 or less and / or a dielectric dissipation factor of 0.0102 or more and 0.0197 or less, when the optical sheet 1 is incorporated into a display device DP together with a touch panel 30, malfunction of the touch panel can be suitably suppressed. The present inventors have found the relationship between the value of such relative dielectric constant and / or dielectric dissipation factor and the obtained effect through extensive research, and have arrived at the present invention. Such relative dielectric constant and / or dielectric dissipation factor of the optical sheet 1 can be set by appropriately adjusting the material and thickness of the substrate 11, the material and thickness of the optical functional layer 12 and the content of the light absorbing component in the light absorbing portion 12a, the material and thickness of the first ultraviolet curing resin layer 13, etc.

[0038] The thickness of the optical sheet 1 is preferably 100 μm or more and 500 μm or less, and more preferably 250 μm or more and 300 μm or less. The relative dielectric constant and / or dielectric loss tangent vary depending on the thickness, but when the thickness of the optical sheet 1 is within the above range, particularly when it is 250 μm or more and 300 μm or less, it becomes easy to set the relative dielectric constant and / or dielectric loss tangent within the above desired range, and handling becomes easy due to the securing of an appropriate thickness.

[0039] (base material) The substrate 11 is a transparent substrate having optical transparency made of resin, glass, or the like, and is composed of, for example, a film mainly composed of polycarbonate, triacetyl cellulose (TAC), polyethylene terephthalate (PET), polyolefin, polyacrylate, or polyamide, glass, etc. The thickness of the substrate 11 is, for example, 60 μm or more and 250 μm or less, and the refractive index of the substrate 11 is, for example, 1.46 or more and 1.67 or less. Note that the term "main component" refers to a component that is contained in a proportion of 50% or more of the entire substance, or the component that is contained in the largest amount, among multiple components that constitute a certain substance.

[0040] The relative dielectric constant of the substrate 11 itself at 25° C. in accordance with JIS C 2138:2007 is preferably 3.1 or more and 3.6 or less in the frequency range of 1 KHz to 1 MHz. The dielectric dissipation factor of the substrate 11 itself at 25° C. in accordance with JIS C 2138:2007 is preferably 0.0100 or more and 0.0200 or less in the frequency range of 1 KHz to 1 MHz.

[0041] When the dielectric constant and / or dielectric loss tangent of the substrate 11 itself is within the above range, it is easy to set the dielectric constant of the optical sheet 1 to the above range of 3.18 or more and 3.51 or less, and the dielectric loss tangent to the above range of 0.0102 or more and 0.0197 or less. However, even when the dielectric constant and / or dielectric loss tangent of the substrate 11 itself is within the above range, the dielectric constant and / or dielectric loss tangent of the optical sheet 1 may deviate from the desired range depending on the material, thickness, etc. of the optical functional layer 12 and the first ultraviolet cured resin layer 13. However, even in such a case, the optical sheet 1 having the desired dielectric constant and / or dielectric loss tangent can be obtained as long as the material, thickness, etc. of the optical functional layer 12 and the first ultraviolet cured resin layer 13 are appropriately set.

[0042] (optical functional layer) The optical functional layer 12 is a so-called louver film having light absorbing portions 12a and light transmitting portions 12b, and the light transmitting portions 12b and the light absorbing portions 12a are alternately arranged along a first direction D1 parallel to each of a pair of main surfaces of the optical functional layer 12. The reference symbol D2 in Fig. 1 indicates a second direction parallel to each of the pair of main surfaces and perpendicular to the first direction D1, and the light absorbing portions 12a and the light transmitting portions 12b extend linearly in the second direction D2. Note that the first direction D1 and the second direction D2 do not have to be perpendicular to each other.

[0043] The light absorbing portion 12a is a portion that absorbs light, and light absorbing particles are contained in a base resin, in other words, a binder resin. For example, acrylic beads containing carbon black can be used as the light absorbing particles. Note that the light absorbing portion 12a may be a binder resin containing, for example, a black filler, and the composition is not particularly limited.

[0044] The optical sheet 1 is installed so as to transmit image light from the optical functional layer 12 toward the substrate 11, and adjusts the orientation of the image light by the light absorbing portion 12a, for example, and the cross-sectional shape of the light absorbing portion 12a in this embodiment is a trapezoidal shape tapered toward the light exit side. On the other hand, the cross-sectional shape of the light transmitting portion 12b is a trapezoidal shape tapered toward the light entrance side. However, the cross-sectional shapes of the light absorbing portion 12a and the light transmitting portion 12b can adopt various shapes according to the required function, and are not particularly limited, and may be, for example, a rectangular shape.

[0045] In the following, of the pair of main surfaces of the optical functional layer 12, the main surface on the light-entering side is referred to as the first main surface 121, and the main surface on the light-emitting side is referred to as the second main surface 122. The above-mentioned base material 11 is provided on the second main surface 122 of the optical functional layer 12, and the first ultraviolet-cured resin layer 13 is provided on the first main surface 121 of the optical functional layer 12. In this embodiment, one of the outermost surfaces of the optical sheet 1 (the surface located on the lower side in the figure) is formed by the first ultraviolet-cured resin layer 13, and the other of the outermost surfaces of the optical sheet (the surface located on the upper side in the figure) is formed by the surface of the base material 11 opposite to the optical functional layer 12 side.

[0046] The optical functional layer 12 in this embodiment further includes a film-like land portion 12c that is integrated with the light transmitting portion b in a state spanning the plurality of light transmitting portions 12b and is made of the same material as the light transmitting portion 12b. The light absorbing portion 12a is exposed from a first main surface 121 (the surface on the lower side in the figure) that is one of a pair of main surfaces of the optical functional layer 12, and the land portion 12c forms a second main surface 122 that is the other of the pair of main surfaces of the optical functional layer 12, is bonded to the base material 11, and covers the light absorbing portion 12a from the base material 11 side. However, the optical functional layer 12 does not necessarily have to include the land portion 12c as described above.

[0047] The material constituting the base resin in the light absorbing portion 12a is not particularly limited, but is preferably a curable resin. Specifically, for example, an ionizing radiation curable resin, which is a resin cured by ultraviolet light or electron beam, a mixture of an ionizing radiation curable resin and a solvent drying type resin (a resin that becomes a coating by simply drying a solvent added to adjust the solid content during coating), or a thermosetting resin may be mentioned. The refractive index of the base resin in the light absorbing portion 12a is preferably 1.47 or more and 1.65 or less, more preferably 1.49 or more and 1.57 or less. If the refractive index of the base resin is high, the light absorbing portion 12a is likely to crack, so the refractive index is preferably 1.57 or less. From the viewpoint of reducing the relative dielectric constant and / or dielectric loss tangent and suppressing the deterioration of optical performance, it is preferable to form the light absorbing portion 12a from an ultraviolet curable acrylic resin, for example, an ultraviolet curable urethane acrylate.

[0048] On the other hand, the light transmitting portion 12b is a portion that transmits light, and is made of, for example, a resin that transmits visible light. The material of the light transmitting portion 12b is not particularly limited, but is preferably a curable resin. Specific examples include an ionizing radiation curable resin that is a resin that is cured by ultraviolet light or an electron beam, a mixture of an ionizing radiation curable resin and a solvent drying resin (a resin that becomes a coating by simply drying a solvent added to adjust the solid content during coating), and a thermosetting resin.

[0049] In addition, since the light transmitting portion 12b in this embodiment is bonded to the base material 11, it is desirable that the light transmitting portion 12b is compatible with the base material 11 in terms of improving the bonding strength with the base material 11. In addition, since the voids formed in the light transmitting portion 12b to fill the light absorbing portion 12a are formed, for example, by a mold, it is desirable that the light transmitting portion 12b has a property that allows good release by, for example, containing a release agent. For example, when the base material 11 is mainly composed of polycarbonate, a material containing phenoxyethyl acrylate in terms of improving the bonding strength and a phosphate ester in terms of ensuring releasability can be suitably used as the material of the light transmitting portion 12b that can satisfy the above two requirements.

[0050] In addition, the refractive index of the light-transmitting portion 12b is preferably 1.47 or more and 1.65 or less, and more preferably 1.49 or more and 1.57 or less. If the refractive index is high, the light-transmitting portion 12b is easily cracked, so the refractive index is preferably 1.57 or less. In addition, the refractive index of the light-transmitting portion 12b is preferably higher than or equal to the refractive index of the base resin of the light-absorbing portion 12a. When the refractive index of the light-transmitting portion 12b is higher than the refractive index of the base resin of the light-absorbing portion 12a, optical design using total reflection of light from the light-transmitting portion 12b toward the light-absorbing portion 12a becomes possible, and for example, the light utilization efficiency can be improved. In addition, when the refractive index of the light-transmitting portion 12b is the same as the refractive index of the base resin of the light-absorbing portion 12a, total reflection and refraction of light do not occur, so that it is possible to prevent the occurrence of double images of transmitted light, total reflected light, and refracted light even if the distance from the surface of the display device to the optical sheet 1 is large, for example. From the viewpoint of reducing the relative dielectric constant and / or the dielectric loss tangent and suppressing the deterioration of the optical performance, it is preferable to form the light transmitting portion 12b from an ultraviolet-curable acrylic resin, for example, an ultraviolet-curable urethane acrylate.

[0051] In addition, the pitch of the arrangement of the light absorbing portion 12a and the light transmitting portion 12b in the optical functional layer 12 is not particularly limited, but from the viewpoint of effectively exerting the function of the louver film, it is preferably 15 μm or more and 100 μm or less, and more preferably 30 μm or more and 100 μm or less. In addition, the height (thickness) of the light absorbing portion 12a is preferably 60 μm or more and 150 μm or less. In addition, the thickness of the land portion 12c is preferably 10 μm or more and 50 μm or less. In addition, the maximum width (width of the end portion on the exposed side) of the light absorbing portion 12a in the first direction D1 is preferably 5 μm or more and 15 μm or less. If it is smaller than 5 μm, there is a risk that the optical performance will be impaired, and if it is larger than 15 μm, there is a risk that it will be difficult to reduce the relative dielectric constant and / or dielectric loss tangent.

[0052] The relative dielectric constant of the optical functional layer 12 itself at 25°C according to JIS C 2138:2007 is preferably 3.1 to 3.6 in the frequency range of 1 KHz to 1 MHz. The dielectric dissipation factor of the optical functional layer 12 itself at 25°C according to JIS C 2138:2007 is preferably 0.0100 to 0.0200 in the frequency range of 1 KHz to 1 MHz.

[0053] When the dielectric constant and / or dielectric loss tangent of the optical functional layer 12 itself is within the above range, it is easy to set the dielectric constant of the optical sheet 1 to the above-mentioned range of 3.18 or more and 3.51 or less, and the dielectric loss tangent to the above-mentioned range of 0.0102 or more and 0.0197 or less. However, even when the dielectric constant and / or dielectric loss tangent of the optical functional layer 12 itself is within the above range, the dielectric constant and / or dielectric loss tangent of the optical sheet 1 may deviate from the desired range depending on the material, thickness, etc. of the substrate 11 and the first ultraviolet cured resin layer 13. However, even in such a case, the optical sheet 1 having the desired dielectric constant and / or dielectric loss tangent can be obtained as long as the material, thickness, etc. of the substrate 11 and the first ultraviolet cured resin layer 13 are appropriately set.

[0054] Here, when the light absorbing particles in the light absorbing portion 12a contain a dielectric such as carbon black, the dielectric may increase the relative dielectric constant and / or dielectric loss tangent of the optical sheet 1. On the other hand, when the amount of the dielectric such as carbon black is reduced in order to reduce the relative dielectric constant and / or dielectric loss tangent, the optical performance of the light absorbing portion 12a may be deteriorated. From the viewpoint of suppressing the relative dielectric constant and / or dielectric loss tangent and suppressing the deterioration of the optical performance, when the light absorbing portion 12a contains a base resin and light absorbing particles held by the base resin, and the light absorbing particles contain carbon black, it is preferable that the light absorbing particles are contained in an amount of 10 parts by weight or more and 30 parts by weight or less when the light absorbing portion 12a is taken as 100 parts by weight. And, it is preferable that the carbon black is contained in an amount of 10 parts by weight or more and 50 parts by weight or less with respect to 100 parts by weight of the light absorbing particles. By not excessively decreasing or increasing the content of the derivative such as carbon black, it becomes easier to achieve both the suppression of the relative dielectric constant and / or dielectric loss tangent and the suppression of the deterioration of the optical performance.

[0055] (First UV-curable resin layer) The first ultraviolet cured resin layer 13 has a function of protecting the optical functional layer 12 by covering the optical functional layer 12. The inventors of the present invention have also found that the relative dielectric constant and dielectric loss tangent can be effectively suppressed by covering only the optical functional layer 12 side with a layer made of ultraviolet cured resin, and have bonded the first ultraviolet cured resin layer 13 to the optical functional layer 12. The thickness of the first ultraviolet cured resin layer 13 is, for example, 5 μm or more and 50 μm or less, and the refractive index of the first ultraviolet cured resin layer 13 is, for example, 1.47 or more and 1.65 or less.

[0056] The material of the first ultraviolet cured resin layer 13 is not particularly limited, but is preferably a curable resin. Specific examples include an ionizing radiation curable resin that is cured by ultraviolet light or an electron beam, and a mixture of an ionizing radiation curable resin and a solvent drying resin (a resin that becomes a coating by simply drying a solvent added to adjust the solid content during coating).

[0057] In this embodiment, when the optical sheet 1 is incorporated into a display device, it is assumed that the first ultraviolet cured resin layer 13 will be adjacent to another optical member, specifically, the surface material of the organic LED panel 15. In this situation, even if the first ultraviolet cured resin layer 13 comes into contact with the other optical member, it is desired that the first ultraviolet cured resin layer 13 does not damage the other optical member and does not come into close contact with the other optical member. Therefore, it is desirable that the first ultraviolet cured resin layer 13 ensures high sliding properties, and in order to satisfy this, a slip agent may be included. As the slip agent, higher fatty acid ester, higher fatty acid aluminide, wax (paraffin wax, polyolefin wax), silicone oil, etc. may be used. In addition, the first ultraviolet cured resin layer 13 in this embodiment is formed as a matte layer, and the surface is rough. This makes it easy to avoid adhesion with the organic LED panel 15. In addition, from the viewpoint of reducing the relative dielectric constant and / or dielectric loss tangent and suppressing the deterioration of optical performance, it is preferable to form the first ultraviolet cured resin layer 13 from an ultraviolet cured acrylic resin, for example, an ultraviolet cured urethane acrylate.

[0058] The first ultraviolet cured resin layer 13 itself preferably has a relative dielectric constant at 25°C in accordance with JIS C 2138:2007 of 3.1 or more and 3.6 or less in the frequency range of 1 KHz to 1 MHz. Also, the first ultraviolet cured resin layer 13 itself preferably has a dielectric loss tangent at 25°C in accordance with JIS C 2138:2007 of 0.0100 or more and 0.0200 or less in the frequency range of 1 KHz to 1 MHz.

[0059] When the dielectric constant and / or dielectric loss tangent of the first ultraviolet cured resin layer 13 itself is within the above range, it is easy to set the dielectric constant of the optical sheet 1 to the above range of 3.18 or more and 3.51 or less, and the dielectric loss tangent to the above range of 0.0102 or more and 0.0197 or less. However, even when the dielectric constant and / or dielectric loss tangent of the first ultraviolet cured resin layer 13 itself is within the above range, the dielectric constant and / or dielectric loss tangent of the optical sheet 1 may deviate from the desired range depending on the material, thickness, etc. of the substrate 11 and the optical functional layer 12. However, even in such a case, the optical sheet 1 having the desired dielectric constant and / or dielectric loss tangent can be obtained as long as the material, thickness, etc. of the substrate 11 and the optical functional layer 12 are appropriately set.

[0060] The optical sheet 1 according to the first embodiment described above includes a base material 11 and an optical functional layer 12. More specifically, the optical sheet 1 further includes a first ultraviolet curing resin layer 13, one of the outermost surfaces of the optical sheet 1 being formed by the first ultraviolet curing resin layer 13, and the other of the outermost surfaces of the optical sheet being formed by the surface of the base material 11 opposite to the optical functional layer 12 side. The optical sheet 1 is configured so that the relative dielectric constant at 25°C conforming to JIS C 2138:2007 is 3.18 or more and 3.51 or less in the frequency range of 1 KHz or more and 1 MHz or less, and / or the dielectric loss tangent at 25°C conforming to JIS C 2138:2007 is 0.0102 or more and 0.0197 or less in the frequency range of 1 KHz or more and 1 MHz or less.

[0061] In such optical sheet 1, since the relative dielectric constant and / or dielectric loss tangent is not excessively large, malfunction of touch panel 30 when incorporated into a display device DP together with touch panel 30 can be suitably suppressed.

[0062] <<Second embodiment>> Next, an optical sheet 2 according to a second embodiment will be described with reference to Fig. 3. The optical sheet 2 shown in Fig. 3 includes a base material 11, an optical functional layer 12, a first ultraviolet cured resin layer 13, and a second ultraviolet cured resin layer 14. In this embodiment, one of the outermost surfaces of the optical sheet 1 (the surface located on the lower side in the figure) is formed by the first ultraviolet cured resin layer 13, and the other of the outermost surfaces of the optical sheet 1 (the surface located on the upper side in the figure) is formed by the second ultraviolet cured resin layer 14.

[0063] Like the first embodiment, this optical sheet 2 is configured so that the relative dielectric constant at 25°C in accordance with JIS C 2138:2007 is 3.18 or more and 3.51 or less in the frequency range of 1 KHz or more and 1 MHz or less, and / or the dielectric tangent at 25°C in accordance with JIS C 2138:2007 is 0.0102 or more and 0.0197 or less in the frequency range of 1 KHz or more and 1 MHz or less. Here, the thickness of the optical sheet 2 is preferably 100 μm or more and 500 μm or less, and more preferably 270 μm or more and 450 μm or less. When the thickness of the optical sheet 1 is within the above range, particularly when it is 270 μm or more and 450 μm or less, it becomes easier to set the relative dielectric constant and / or dielectric loss tangent to the desired range. The thickness of the base material 11 is, for example, 50 μm or more, preferably 60 μm or more, and more preferably 80 μm or more. Other preferable conditions of the base material 11, the optical functional layer 12, and the first ultraviolet cured resin layer 13 are the same as those of the first embodiment.

[0064] The second ultraviolet cured resin layer 14 is provided, for example, to protect the substrate 11. The thickness of the second ultraviolet cured resin layer 14 is, for example, 5 μm or more and 50 μm or less, and the refractive index of the second ultraviolet cured resin layer 14 is, for example, 1.47 or more and 1.65 or less. The material of the second ultraviolet cured resin layer 14 is not particularly limited, but is preferably a curable resin. Specifically, for example, an ionizing radiation curable resin that is a resin that is cured by ultraviolet light or an electron beam, a mixture of an ionizing radiation curable resin and a solvent drying type resin (a resin that becomes a coating by simply drying a solvent added to adjust the solid content during coating), or a thermosetting resin may be mentioned. From the viewpoint of reducing the relative dielectric constant and / or dielectric loss tangent and suppressing the deterioration of optical performance, it is preferable to form the second ultraviolet cured resin layer 14 from an ultraviolet curable acrylic resin, for example, an ultraviolet curable urethane acrylate.

[0065] In addition, the second ultraviolet cured resin layer 14 is preferably formed of the same material and with the same thickness as the first ultraviolet cured resin layer 13. In this case, the linear expansion coefficient of the second ultraviolet cured resin layer 14 and the linear expansion coefficient of the first ultraviolet cured resin layer 13 can be made uniform, and defects such as curling can be suppressed. In addition, the manufacturing cost can be suppressed.

[0066] The optical sheet 2 according to the second embodiment described above also has an excessively large relative dielectric constant and / or dielectric loss tangent, and therefore can suitably suppress malfunction of the touch panel 30 when incorporated into a display device DP together with the touch panel 30. As will be shown in the examples described later, the optical sheet 2 according to the second embodiment tends to have a greater relative dielectric constant and dielectric loss tangent than the optical sheet 1 according to the first embodiment, which is under almost the same conditions except that it does not include the second ultraviolet-cured resin layer 14. However, the optical sheet 2 according to the second embodiment can ensure good durability and ease of use by having the second ultraviolet-cured resin layer 14.

[0067] <<Third embodiment>> Next, an optical sheet 3 according to a third embodiment will be described with reference to Fig. 4. The optical sheet 3 shown in Fig. 4 includes a base material 11 and an optical functional layer 12, and one of the outermost surfaces of the optical sheet 1 (the surface located on the lower side in the figure) is formed by the surface of the optical functional layer 12 opposite to the base material 11 side, and the other of the outermost surfaces of the optical sheet (the surface located on the upper side in the figure) is formed by the surface of the base material 11 opposite to the optical functional layer 12 side.

[0068] As in the first embodiment, the optical sheet 3 is configured so that the relative dielectric constant at 25°C conforming to JIS C 2138:2007 is 3.18 to 3.51 in the frequency range of 1 KHz to 1 MHz, and / or the dielectric loss tangent at 25°C conforming to JIS C 2138:2007 is 0.0102 to 0.0197 in the frequency range of 1 KHz to 1 MHz. The thickness of the optical sheet 3 is preferably 500 μm or less, the thickness of the substrate 11 is preferably 50 μm or more, and it is more preferable that the thickness of the optical sheet 3 is 220 μm or less and the thickness of the substrate 11 is 50 μm or more. Other preferable conditions of the substrate 11 and the optical functional layer 12 are the same as those in the first embodiment.

[0069] The optical sheet 3 according to the third embodiment described above also has an excessively large relative dielectric constant and / or dielectric loss tangent, and therefore can suitably suppress malfunction of the touch panel 30 when incorporated into a display device DP together with the touch panel 30. In this embodiment, the relative dielectric constant and / or dielectric loss tangent is suppressed by suppressing the overall thickness of the optical sheet 1. The optical sheet 3 according to the third embodiment has a simple two-layer structure, which can improve productivity.

[0070] <<Modifications>> In the first embodiment, the optical sheet 1 is provided between the organic LED panel 15 and the touch panel 30, but the optical sheets 1 to 3 may be provided on the cover glass 40 of the display device as shown in the modified example of FIG. 5. In this case, the optical sheets 1 to 3 exert a peep suppression function. On the other hand, when the optical sheets 1 to 3 are provided on the cover glass 40, if the relative dielectric constant and the dielectric loss tangent are excessively low, the sensitivity of the touch panel 30 may be impaired. Here, when the relative dielectric constant at 25°C of the optical sheets 1 to 3 conforming to JIS C 2138:2007 is 3.18 to 3.51 in the frequency range of 1 KHz to 1 MHz, and when the dielectric loss tangent at 25°C conforming to JIS C 2138:2007 is 0.0102 to 0.0197 in the frequency range of 1 KHz to 1 MHz, the sensitivity of the touch panel 30 is favorable and malfunction is suppressed. Therefore, the optical sheets 1 to 3 are useful no matter which side of the touch panel 30 they are placed on.

[0071] In addition, in each of the embodiments described above, it is assumed that the optical sheets 1 to 3 are used together with the organic LED panel 15, but the optical sheets 1 to 3 may form a display device together with a liquid crystal panel. Also, the optical sheet may include only the base material 11, the optical functional layer 12, and the second ultraviolet cured resin layer 14. EXAMPLES

[0072] Examples 1 to 4 of the present invention and Comparative Example 1 will be described below. Examples 1 to 4 and Comparative Example 1 were produced using a mold having a convex portion corresponding to the shape of the light absorbing section 12a. The convex portion of the mold used in producing Examples 1 to 4 has a tapered shape, with a width of 4 μm on the tip side and a width of 10 μm on the base side. The height of the convex portion is 102 μm. The convex portions are arranged at a pitch of 39 μm. In the mold used in producing Comparative Example 1, the height of the convex portion is 120 μm.

[0073] Example 1 Example 1 corresponds to the first embodiment, and includes a base material 11, an optical function layer 12, and a first ultraviolet curable resin layer 13. As the substrate 11, a polycarbonate film (Carboglass, manufactured by AGC Corporation) having a thickness of 130 μm was used. An ultraviolet-curable urethane acrylate with a refractive index of 1.56 was used as a material for forming the light-transmitting portion 12b of the optical function layer 12. Then, the ultraviolet-curable urethane acrylate was provided on the substrate 11, and a recess corresponding to the shape of the light-absorbing portion 12a was formed using the above-mentioned mold, and then curing was performed using a release mold and UV irradiation, thereby forming a land portion 12c with a thickness of 12 μm and the light-transmitting portion 12b on the substrate 11.

[0074] A material containing a base resin made of ultraviolet-curable urethane acrylate with a refractive index of 1.49 and light-absorbing particles made of acrylic beads with an average particle size of 4 μm containing carbon black was used as the material for forming the light-absorbing portion 12a of the optical functional layer 12. The light-absorbing particles were contained in an amount of 20% by weight in the entire material. The material for forming the light-absorbing portion 12a was then applied to the light-transmitting portion 12b, pushed into the recessed portion with a doctor blade, and then cured by UV irradiation to form the light-absorbing portion 12a. An ultraviolet-curable urethane acrylate with a refractive index of 1.51 was used as a material for forming the first ultraviolet-curable resin layer 13. This ultraviolet-curable urethane acrylate was provided on the light-absorbing portion 12a, and a mold was pressed against it so as to form a matte surface, followed by curing by UV irradiation, thereby forming the first ultraviolet-curable resin layer 13.

[0075] The thickness of each element and the total thickness of the optical sheet in Example 1 are as follows. The thickness of the substrate 11 is 130 μm. The land portion 12c of the optical function layer 12 has a thickness of 12 μm. The thickness of the light transmitting portion 12b of the optical function layer 12 is 102 μm. The thickness of the light absorbing portion 12a in the optical function layer 12 is 102 μm. The first ultraviolet curing resin layer 13 has a thickness of 25 μm. The total thickness of the optical sheet is 269 μm.

[0076] Example 2 Example 2 corresponds to the second embodiment, and includes a base material 11, an optical function layer 12, a first ultraviolet cured resin layer 13, and a second ultraviolet cured resin layer . As the substrate 11, a polycarbonate film (Carboglass, manufactured by AGC Corporation) having a thickness of 130 μm was used. As a material for forming the light transmitting portion 12b of the optical function layer 12, ultraviolet curing urethane acrylate with a refractive index of 1.56 was used. A material containing a base resin made of ultraviolet-curable urethane acrylate with a refractive index of 1.49 and light-absorbing particles made of acrylic beads with an average particle size of 4 μm containing carbon black was used as the material for forming the light-absorbing portion 12a of the optical function layer 12. The light-absorbing particles were contained in an amount of 20% by weight in the entire material. As a material for forming the first ultraviolet curing resin layer 13, ultraviolet curing urethane acrylate having a refractive index of 1.51 was used. The procedure for forming the optical function layer 12 and the first ultraviolet curing resin layer 13 is the same as in the first embodiment. On the other hand, ultraviolet-curable urethane acrylate with a refractive index of 1.51 was used as a material for forming the second ultraviolet-curable resin layer 14. The ultraviolet-curable urethane acrylate was provided on the substrate 11, and a mold was pressed against it so as to form a matte surface, followed by curing by UV irradiation, thereby forming the second ultraviolet-curable resin layer 14.

[0077] The thickness of each element and the total thickness of the optical sheet in Example 2 are as follows. The thickness of the substrate 11 is 130 μm. The land portion 12c of the optical function layer 12 has a thickness of 29 μm. The thickness of the light transmitting portion 12b of the optical function layer 12 is 102 μm. The thickness of the light absorbing portion 12a in the optical function layer 12 is 102 μm. The first ultraviolet curing resin layer 13 has a thickness of 25 μm. The second ultraviolet curing resin layer 14 has a thickness of 25 μm. The total thickness of the optical sheet is 311 μm.

[0078] Example 3 Example 3 corresponds to the second embodiment, and includes a base material 11, an optical function layer 12, a first ultraviolet cured resin layer 13, and a second ultraviolet cured resin layer . As the substrate 11, a polycarbonate film (Carboglass, manufactured by AGC Corporation) having a thickness of 250 μm was used. As a material for forming the light transmitting portion 12b of the optical function layer 12, ultraviolet curing urethane acrylate with a refractive index of 1.56 was used. A material containing a base resin made of ultraviolet-curable urethane acrylate with a refractive index of 1.49 and light-absorbing particles made of acrylic beads with an average particle size of 4 μm containing carbon black was used as the material for forming the light-absorbing portion 12a of the optical function layer 12. The light-absorbing particles were contained in an amount of 20% by weight in the entire material. As a material for forming the first ultraviolet curing resin layer 13, ultraviolet curing urethane acrylate having a refractive index of 1.51 was used. As a material for forming the second ultraviolet curing resin layer 14, ultraviolet curing urethane acrylate with a refractive index of 1.51 was used. The procedure for forming each layer was the same as in Example 2.

[0079] The thickness of each element and the total thickness of the optical sheet in Example 3 are as follows. The thickness of the substrate 11 is 250 μm. The land portion 12c of the optical function layer 12 has a thickness of 19 μm. The thickness of the light transmitting portion 12b of the optical function layer 12 is 102 μm. The thickness of the light absorbing portion 12a in the optical function layer 12 is 102 μm. The first ultraviolet curing resin layer 13 has a thickness of 25 μm. The second ultraviolet curing resin layer 14 has a thickness of 25 μm. The total thickness of the optical sheet is 421 μm.

[0080] Example 4 Example 4 corresponds to the third embodiment and includes a base material 11 and an optical function layer 12. As the substrate 11, a polycarbonate film (Carboglass, manufactured by AGC Corporation) having a thickness of 100 μm was used. As a material for forming the light transmitting portion 12b of the optical function layer 12, ultraviolet curing urethane acrylate with a refractive index of 1.56 was used. A material containing a base resin made of ultraviolet-curable urethane acrylate with a refractive index of 1.49 and light-absorbing particles made of acrylic beads with an average particle size of 4 μm containing carbon black was used as the material for forming the light-absorbing portion 12a of the optical function layer 12. The light-absorbing particles were contained in an amount of 20% by weight in the entire material. The procedure for forming the optical function layer 12 is the same as in the first embodiment.

[0081] The thickness of each element and the total thickness of the optical sheet in Example 4 are as follows. The thickness of the substrate 11 is 100 μm. The thickness of the land portion 12c of the optical function layer 12 is 18 μm. The thickness of the light transmitting portion 12b of the optical function layer 12 is 102 μm. The thickness of the light absorbing portion 12a in the optical function layer 12 is 102 μm. The total thickness of the optical sheet is 220 μm.

[0082] Comparative Example 1 Comparative Example 1 includes a substrate and an optical functional layer similar to those of the embodiment, but a bonding substrate is provided on the optical functional layer via an ultraviolet-curable adhesive. A polycarbonate film (Carboglass, manufactured by AGC Corporation) having a thickness of 130 μm was used as the substrate. The material for forming the light transmitting portion of the optical functional layer was an ultraviolet-curable urethane acrylate having a refractive index of 1.56. The material used for the light-absorbing portion of the optical functional layer is a material containing a base resin made of UV-curable urethane acrylate with a refractive index of 1.49 and light-absorbing particles made of acrylic beads with an average particle size of 4 μm containing carbon black. The light-absorbing particles are contained in the entire material at 20% by weight. The UV-curable adhesive has a thickness of 25 μm. The substrate for lamination is a polycarbonate film having a thickness of 100 μm.

[0083] The thickness of each element and the total thickness of the optical sheet in Comparative Example 1 are as follows. The thickness of the substrate is 130 μm. The thickness of the land portion of the optical function layer is 42 μm. The thickness of the light transmitting portion of the optical functional layer is 120 μm. The thickness of the light absorbing portion of the optical functional layer is 120 μm. The thickness of the ultraviolet-curing adhesive is 25 μm. The thickness of the lamination substrate is 100 μm. The total thickness of the optical sheet is 417 μm.

[0084] The dimensional conditions of Examples 1 to 4 and Comparative Example 1, and the measurement results of the dielectric constant and dielectric loss tangent of each are shown in Table 1 below. The dielectric constant and dielectric loss tangent were measured in an environment of 25°C by the automatic balancing bridge method in accordance with JIS C 2138:2007. A Precision LCR meter E4980A (manufactured by Agilent Technologies, Inc.) was used for the measurement. The dielectric constant and dielectric loss tangent were measured at 1KHz, 10KHz, 100KHz, and 1MHz.

[0085] [Table 1]

[0086] In each of Examples 1 to 4, the relative dielectric constant at 25° C. conforming to JIS C 2138: 2007 is 3.18 or more and 3.51 or less in the frequency range of 1 KHz or more and 1 MHz or less, and the dielectric dissipation factor at 25° C. conforming to JIS C 2138: 2007 is 0.0102 or more and 0.0197 or less in the frequency range of 1 KHz or more and 1 MHz or less. When these optical sheets were used together with the touch panel 30, no malfunction of the touch panel 30 was confirmed.

[0087] Example 1 is almost the same as Example 2 except that the second ultraviolet cured resin layer 14 is not provided, but the relative dielectric constant and dielectric loss tangent are lower than those of Example 2. According to this result, in order to suppress the relative dielectric constant and dielectric loss tangent, it can be said that it is effective to cover only the optical function layer 12 side with a layer made of ultraviolet cured resin. In addition, from the results of Example 2 and Example 3, it can be said that when the first and second ultraviolet cured resin layers 13, 14 are both urethane acrylate, the relative dielectric constant and dielectric loss tangent are effectively suppressed to be low. On the other hand, comparing Example 2 and Example 3, Example 3, in which the thickness of the substrate 11 is larger, has a lower relative dielectric constant and dielectric loss tangent than Example 2. According to this result, in a configuration in which the first ultraviolet cured resin layer 13 and the second ultraviolet cured resin layer 14 form the outermost surfaces, it is presumed that the thicker the substrate 11 between them, the lower the relative dielectric constant and dielectric loss tangent. In Example 2, the thickness of the substrate 11 is 130 μm, and the relative dielectric constant at 1 KHz is 3.49 and the dielectric loss tangent is 0.0190. Considering these values, it is estimated that if the thickness of the substrate 11 is 130 μm or more, the relative dielectric constant will be 3.18 to 3.51 inclusive and the dielectric tangent will be 0.0102 to 0.0197 inclusive in the frequency range of 1 KHz to 1 MHz inclusive. In addition, in Example 4, it is presumed that the dielectric constant and the dielectric loss tangent are suppressed due to the thin thickness of the optical sheet. In general, the dielectric constant and the dielectric loss tangent are lower as the thickness of the dielectric is smaller. In Example 4, the thickness is 220 μm, and the dielectric constant at 1 KHz is 3.51, and the dielectric loss tangent at 1 MHZ is 0.0196. Therefore, when the optical sheet 1 is composed of the substrate 11 and the optical functional layer 12, if the total thickness is 220 μm or less and the thickness of the substrate 11 is 100 μm or more, it is presumed that the dielectric constant is 3.18 to 3.51 in the frequency range of 1 KHz to 1 MHz, and the dielectric loss tangent is 0.0102 to 0.0197 in the frequency range.

[0088] On the other hand, the relative dielectric constant and dielectric loss tangent are high in Comparative Example 1. This is considered to be due to the overall thickness, the ultraviolet-curing adhesive, and the material of the lamination base material. [Explanation of symbols]

[0089] 1,2,3...Optical sheet 11...Base material 12...Optical functional layer 121…First main surface 122…Second main surface 12a...Light absorbing part 12b...Light transmission part 12c…Land section 13...First UV-curable resin layer 14...Second UV-curable resin layer

Claims

1. A display panel, an optical sheet provided on the display panel; The optical sheet includes a base material and an optical functional layer bonded to the base material, the optical functional layer has a light absorbing portion and a light transmitting portion, the refractive index of the light transmitting portion is higher than the refractive index of the light absorbing portion, the light absorbing portion has a trapezoidal shape tapered toward a light output side in a direction in which light transmits from the display panel toward the base material, The relative dielectric constant of the optical sheet at 25° C. according to JIS C 2138:2007 is 3.18 to 3.51 in the frequency range of 1 KHz to 1 MHz, The optical sheet further includes a first ultraviolet curing resin layer provided on a surface of the optical functional layer opposite to the substrate side, the first ultraviolet curing resin layer contains urethane acrylate, one of the outermost surfaces of the optical sheet is formed by the first ultraviolet curing resin layer, and the other of the outermost surfaces of the optical sheet is formed by a surface of the base material opposite to the optical functional layer side; The thickness of the optical sheet is 100 μm or more and 500 μm or less, the light absorbing portion includes a base resin and light absorbing particles held by the base resin; The light absorbing particles include carbon black; The light absorbing particles are contained in an amount of 10 parts by weight or more and 30 parts by weight or less relative to 100 parts by weight of the light absorbing portion, The display device, wherein the carbon black is contained in an amount of 10 parts by weight or more and 50 parts by weight or less with respect to 100 parts by weight of the light absorbing particles.

2. the optical function layer further includes a land portion that is integral with the light transmitting portion in a state spanning a plurality of the light transmitting portions and is made of the same material as the light transmitting portions, the light absorbing portion is exposed from one of a pair of main surfaces of the optical function layer, The display device according to claim 1 , wherein the land portion forms the other of the pair of main surfaces, is joined to the base material, and covers the light absorbing portion from the base material side.

3. A display panel; an optical sheet provided on the display panel; The optical sheet includes a base material and an optical functional layer bonded to the base material, the optical functional layer has a light absorbing portion and a light transmitting portion, the refractive index of the light transmitting portion is higher than the refractive index of the light absorbing portion, the light absorbing portion has a trapezoidal shape tapered toward a light output side in a direction in which light transmits from the display panel toward the base material, The dielectric tangent of the optical sheet at 25° C. according to JIS C 2138:2007 is 0.0102 or more and 0.0197 or less in the frequency range of 1 KHz or more and 1 MHz or less, The optical sheet further includes a first ultraviolet curing resin layer provided on a surface of the optical functional layer opposite to the substrate side, the first ultraviolet curing resin layer contains urethane acrylate, one of the outermost surfaces of the optical sheet is formed by the first ultraviolet curing resin layer, and the other of the outermost surfaces of the optical sheet is formed by a surface of the base material opposite to the optical functional layer side; The thickness of the optical sheet is 100 μm or more and 500 μm or less, the light absorbing portion includes a base resin and light absorbing particles held by the base resin; The light absorbing particles include carbon black; The light absorbing particles are contained in an amount of 10 parts by weight or more and 30 parts by weight or less with respect to 100 parts by weight of the light absorbing portion, The display device, wherein the carbon black is contained in an amount of 10 parts by weight or more and 50 parts by weight or less with respect to 100 parts by weight of the light absorbing particles.

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