JP2016105132A - Optical film and image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical film that substantially prevents problems caused by warpage or optical adhesion even in a high-temperature environment or a high-temperature and high-humidity environment such as an on-vehicle environment.SOLUTION: The optical film includes: a base layer 28; an optical function layer 22 laminated on one surface of the base layer and having a plurality of light-transmitting portions 23 arranged along a layer surface of the base layer to be able to transmit light, and a light-absorbing portion 24 arranged between adjoining light-transmitting portions to be able to absorb light; and a rough surface-forming layer 21 having a thickness of 15 μm or more and 25 μm or less and laminated on a surface on an opposite side of the optical function layer to the side where the base layer is laminated. The rough surface-forming layer has a rough surface formed on an opposite side to the optical function layer. A surface roughness Ra of the rough surface is 0.1 μm or more and 0.2 μm or less; and the material constituting the rough surface-forming layer is a resin having a crosslinking density of 320 or more and 740 or less.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an optical film that controls light emitted from a light source and emits the light toward an observer, and an image display device including the optical film.

  In a video display device that emits an image to an observer, such as a liquid crystal display, rear projection, organic EL, FED, etc., in order to improve the quality of the image source and the image light from the image source and emit it to the observer The optical film which consists of a several layer which has these various functions is provided.

  For example, Patent Document 1 is disclosed as such an optical film. An optical film described in Patent Document 1 includes an optical functional sheet layer having a prism portion arranged in parallel along a sheet surface so that light can be transmitted, and a light absorbing portion arranged in parallel so as to absorb light between the prism portions. It has. As a result, the image light and the external light are reflected and absorbed to improve the quality of the image light.

  Furthermore, the optical film described in Patent Document 1 is provided with a rough surface forming layer, which makes it difficult to cause unevenness in image light even in an atmosphere of high temperature and high temperature and high humidity.

JP 2010-107660 A

However, even when the optical film described in Patent Document 1 is used, when the video display device is arranged in an environment that requires durability such as in-vehicle, the optical film may be warped. For this reason, there have been many measures to prevent warping with a plurality of substrate layers by further using an additional substrate layer that is stiff and can prevent deformation, but there are problems with the thickness and cost of the optical film. It has occurred.
In particular, in an environment that requires thermal durability, such as in-vehicle, so-called optical adhesion becomes a problem, and an appearance problem due to generation of interference fringes may also occur.

  Therefore, in view of the above problems, an object of the present invention is to provide an optical film in which problems due to warpage and optical adhesion hardly occur even in an environment of high temperature and high temperature and high humidity such as in a vehicle. In addition, an image source unit and an image display device including the optical film are provided.

  The present invention will be described below. In order to facilitate understanding of the present invention, reference numerals in the accompanying drawings are appended in parentheses, but the present invention is not limited to the illustrated embodiment.

  The invention according to claim 1 is an optical film (20) having a plurality of layers, which is laminated on one surface of the base material layer (28) and the base material layer so as to transmit light. An optical functional layer (22) having a plurality of light transmission parts (23) arranged along the layer surface of the light absorption part (24), and a light absorption part (24) arranged to absorb light between adjacent light transmission parts; A rough surface forming layer (21) having a thickness of 15 μm or more and 25 μm or less laminated on a surface opposite to the side on which the base material layer is laminated, of the surface of the optical functional layer, A rough surface is formed on the surface opposite to the optical functional layer, and the surface roughness of the rough surface is 0.1 μm or more and 0.2 μm or less in terms of Ra, and the material constituting the rough surface forming layer is a crosslinking density. The above-mentioned problem is solved by an optical film, which is a resin of 320 or more and 740 or less.

  The invention according to claim 2 is the optical film (20) according to claim 1, wherein the base material layer (28) is made of polycarbonate.

  Invention of Claim 3 is provided with the surface light source device (11), the liquid crystal panel (12), and the optical film (20) of Claim 1 or 2, and an optical film is a surface light source device and a liquid crystal. It is a video source unit arranged between the panels.

  The invention described in claim 4 is a video display device (1) comprising a housing (2) and a video source unit (5) according to claim 3 arranged inside the housing.

  ADVANTAGE OF THE INVENTION According to this invention, even when it uses in the environment where durability is requested | required like a vehicle-mounted etc., it can make it difficult to produce a malfunction about the curvature of an optical film and optical adhesion.

1 is an external perspective view of a video display device 1. FIG. 4 is an exploded perspective view of the video source unit 5. FIG. 4 is a cross-sectional view of the video source unit 5. FIG. FIG. 4 is an enlarged view paying attention to the rough surface forming layer 21 and the optical function layer 22.

  The present invention will be described below based on embodiments shown in the drawings. However, the present invention is not limited to the embodiment. Here, since the elements provided in the present invention are actually very fine and many thin layers, for ease of understanding, some of the elements are shown by being deformed or enlarged. In addition, elements are denoted by reference numerals, but some of the repeated reference numerals may be omitted for the sake of clarity.

FIG. 1 is a perspective view showing an image display apparatus 1 including an image source unit 5, illustrating one embodiment. In FIG. 1, the right side of the page is the observer side. Here, in this embodiment, the video display device 1 is an in-vehicle video display device, and includes, for example, a car navigation device. The video display device 1 includes a housing 2, and a video source unit 5 is built inside the housing 2.
The housing 2 is a member that forms an outer shell of the video display device 1 and that accommodates most of the members constituting the video display device. The housing 2 has an opening, and a so-called screen portion of the image source unit 5 is exposed from the opening so that the image can be viewed. In addition, the video display device 1 includes various known constituent members for functioning as a video display device.

  FIG. 2 is an exploded perspective view of the video source unit 5. In FIG. 2, for ease of understanding, a part of the layers constituting the video source unit is shown separately, but in actuality, they are stacked by being directly overlapped (see FIG. 3). FIG. 3 is a cross-sectional view in the thickness direction including a line indicated by III-III in FIG. 2 (a line in the vertical direction). Further, when the video source unit 5 is arranged on the video display device 1, the right side of FIG. 2 and FIG. 3 is the observer side, and the left side of FIG. 2 and FIG. 3 is the light source side (surface light source device side). It becomes.

  The video source unit 5 includes a video source 10 and a functional layer 30 disposed on the video output side (that is, the observer side) of the video source 10.

  In this embodiment, the image source 10 includes a liquid crystal panel 12. Specifically, the video source 10 includes a surface light source device 11, an optical film 20, and a liquid crystal panel 12. That is, in this embodiment, the optical film 20 is disposed between the surface light source device 11 and the liquid crystal panel 12.

Here, the surface light source device 11 and the liquid crystal panel 12 may have a known structure.
For example, with respect to the surface light source device 11, a reflection sheet, a light guide plate (a light source is disposed on the side surface), and diffusion from the light source side (left side in FIG. 3) to the viewer side (right side in FIG. 3). Examples include a surface light source device in which a sheet, a lens sheet, and a reflective polarizing sheet are laminated in this order.
On the other hand, the liquid crystal panel 12 is laminated in the order of a polarizing filter, a glass substrate, a liquid crystal layer, a glass substrate, and a polarizing filter from the light source side (left side of FIG. 3) to the viewer side (right side of FIG. 3). Liquid crystal panels.

  The optical film 20 is a film disposed on the light emitting side of the surface light source device 11 between the surface light source device 11 and the liquid crystal panel 12 and includes a plurality of layers. In this embodiment, the optical film 20 includes a rough surface forming layer 21, an optical function layer 22, and a base material layer 28 from the surface light source device 11 side. Each layer will be described below. Here, for convenience, the base material layer 28, the optical function layer 22, and the rough surface forming layer 21 will be described in this order.

The base material layer 28 is a layer serving as a base material for forming the optical functional layer 22 on one surface thereof. The base material layer 28 has translucency and supports the optical functional layer 22 so that deformation of the optical functional layer 22 can be prevented. From this viewpoint, as specific examples of the material constituting the base material layer 28, for example, a transparent resin mainly composed of acrylic, styrene, polycarbonate, polyethylene terephthalate (PET), acrylonitrile, triacetyl cellulose (TAC), epoxy acrylate, Examples thereof include urethane acrylate-based reactive resins (ionizing radiation curable resins and the like).
Among these, it is preferable to use TAC, methacrylic resin, and polycarbonate with low birefringence in consideration of the combination with the liquid crystal panel. Furthermore, it is desirable to use a polycarbonate having a high glass transition point in applications that require high heat resistance such as in-vehicle use. Specifically, the glass transition point of polycarbonate is 143 ° C., which is generally suitable for in-vehicle applications that require durability at 105 ° C.

  Although the thickness of the base material layer 28 is not specifically limited, It is preferable that they are 25 micrometers or more and 300 micrometers or less. If the thickness of the base material layer 28 is out of this range, there is a possibility of causing a problem in workability. For example, wrinkles tend to occur when the base material layer 28 is thinner than 25 μm. Moreover, when the base material layer 28 becomes thicker than 300 micrometers, winding of the optical film 20 will become difficult.

  In this embodiment, the optical functional layer 22 has a function of changing the direction of the light to the front direction so that the image light emitted from the image source 10 is not reflected on the windshield of the car, and absorbing a part of light and external light. Have. FIG. 4 shows an enlarged part of FIG. 3 while paying attention to the optical functional layer 22 and the rough surface forming layer 21.

  The optical functional layer 22 has the cross section shown in FIGS. 3 and 4 and has a shape extending in the back / front direction of the paper with respect to the paper. In the present embodiment, in the posture in which the video display device 1 is installed in the vehicle, the extending direction is a horizontal direction. This prevents the image light from being transferred to the windshield as will be described later.

  3 and 4, the optical functional layer 22 has a substantially trapezoidal light transmission part 23 and a light absorption part 24 having a substantially trapezoidal cross section formed between two adjacent light transmission parts 23. It is equipped with. Therefore, in the present embodiment, the light transmission unit 23 and the light absorption unit 24 are alternately arranged in the vertical direction in a posture in which the video display device 1 is installed in the vehicle.

  The light transmission part 23 is a part whose main function is to transmit light. In this embodiment, in the cross section shown in FIG. 3 and FIG. 4, a long lower base, rough surface on the base material layer 28 side (observer side) It is a substantially trapezoid having a short upper base on the forming layer 21 side (surface light source device 11 side). The light transmitting portions 23 extend along the layer surface of the base material layer 28 while maintaining the cross section, and are arranged at a predetermined interval in a direction different from the extending direction. An interval having a substantially trapezoidal cross section is formed between the adjacent light transmission portions 23. Accordingly, the interval has a trapezoidal cross section having a long lower base on the upper base side of the light transmitting portion 23 and a short upper base on the lower base side of the light transmitting portion 23, and is filled with necessary materials described later. As a result, the light absorbing portion 24 is formed. In this embodiment, the adjacent light transmission parts 23 are connected on the long bottom side.

  The light transmission portion 23 has a refractive index of Nt. Such a light transmission part 23 can be formed by hardening a transmission part constituent composition. Details will be described later. The value of the refractive index Nt is not particularly limited. However, as will be described later, the refractive index is 1.55 or more from the viewpoint of appropriately total reflection of light at the interface with the light absorbing portion 24 on the slope of the trapezoidal cross section. It is preferable. However, since a material with a refractive index that is too high is likely to break, the refractive index is preferably 1.61 or less. More preferably, it is 1.56 or less.

  The light absorbing portions 24 are arranged at the above-described intervals formed between the adjacent light transmitting portions 23 and have a cross-sectional shape similar to the cross-sectional shape of the intervals. Therefore, the short upper base faces the base material layer 28 side (observer side), and the long lower base faces the rough surface forming layer 21 side (surface light source device 11 side). And the light absorption part 24 is comprised so that a refractive index may be Nr and it can absorb light. Specifically, light absorbing particles are dispersed in a binder having a refractive index of Nr. The refractive index Nr is preferably a refractive index lower than the refractive index Nt of the light transmission part 23. By making the refractive index of the light absorbing portion 24 smaller than the refractive index of the light transmitting portion 23, the light incident on the light transmitting portion 23 under a predetermined condition can be totally reflected at the interface with the light absorbing portion 24. The value of the refractive index Nr is not particularly limited, but is preferably 1.50 or less from the viewpoint of appropriately performing the total reflection, and more preferably 1.47 or more from the viewpoint of availability. More preferably, it is 1.49 or more.

  The difference in refractive index between the refractive index Nt of the light transmitting portion 23 and the refractive index Nr of the light absorbing portion 24 is not particularly limited, but is preferably 0.05 or more and 0.14 or less. By increasing the refractive index difference, more light can be totally reflected.

  The optical function layer 22 is not particularly limited. For example, the light transmission part 23 and the light absorption part 24 are formed as follows. That is, it is preferable that the pitch of the light transmission part 23 and the light absorption part 24 represented by Pk in FIG. 3 is 20 μm or more and 100 μm or less. Further, the angle formed by the interface on the hypotenuse between the light absorbing portion 24 and the light transmitting portion 23 indicated by θk in FIG. 4 and the normal line of the layer surface of the optical functional layer 22 is 1 ° or more and 10 ° or less. preferable. And it is preferable that the thickness of the light absorption part 24 shown by Dk in FIG. 3 is 50 micrometers or more and 150 micrometers or less. By being within these ranges, the balance between light transmission and light absorption is often appropriate.

  In this embodiment, an example in which the interface between the light transmitting portion 23 and the light absorbing portion 24 is straight in the cross section is shown. However, the present invention is not limited thereto, and may be a polygonal line shape, a convex curved surface shape, a concave curved surface shape, etc. Also good. Moreover, the cross-sectional shape may be the same in the some light transmissive part 23 and the light absorption part 24, and a different cross-sectional shape may have predetermined regularity.

  The rough surface forming layer 21 is laminated on the surface of the optical functional layer 22 opposite to the side on which the base material layer 28 is disposed, and the rough surface 21a is formed on the surface not in contact with the optical functional layer 22. It is a layer that is. The rough surface forming layer 21 has the following characteristics.

  The thickness of the rough surface forming layer 21 (Mt in FIG. 4) is 15 μm or more and 25 μm or less. Here, the thickness of the rough surface forming layer 21 is the distance in the thickness direction between the tip of the rough surface 21a and the layer surface on the side where the rough surface 21a is not formed, as can be seen from Mt shown in FIG. When the thickness is less than 15 μm, it is difficult to obtain a dimensional allowance when forming the rough surface, and there is a possibility that a manufacturing defect may occur. On the other hand, when the thickness is greater than 25 μm, the optical film 20 is likely to warp.

  The rough surface 21a of the rough surface forming layer 21 has a surface roughness Ra (μm) (JIS B 0601 (2001) arithmetic average roughness) of 0.1 μm or more and 0.2 μm or less. If the surface roughness is less than 0.1 μm, the occurrence of interference fringes due to so-called optical adhesion becomes a problem when the optical film 20 is brought into contact with another layer. On the other hand, if the surface roughness is larger than 0.2 μm, irregularities based on this roughness are easily visible to the human eye, which may cause problems in appearance such as scintillation (so-called screen glare).

Further, in the rough surface forming layer 21, the material constituting the rough surface forming layer 21 is a resin, and the molecular weight (crosslinking density) between the crosslinks of the resin is 320 or more and 740 or less. When the molecular weight between crosslinks is smaller than 320, the optical film 20 is likely to be warped. On the other hand, when the molecular weight between crosslinks is larger than 740, the occurrence of interference fringes due to so-called optical adhesion becomes a problem when the optical film 20 is brought into contact with another layer.
Here, the molecular weight between crosslinks can be calculated by a value obtained by dividing the total molecular weight by the number of crosslink points (total molecular weight / number of crosslink points).
The total molecular weight is the sum of the product of the number of moles blended and the molecular weight for each component of the material constituting the rough surface forming layer 21, and is the sum of the products found for each component (Σ (number of moles blended for each component). × Molecular weight of each component)).
The number of crosslinking points refers to the number of functional groups minus 1 for each component of the material constituting the rough surface forming layer 21 and doubles this to obtain the product with the molecular weight, and the sum of the products obtained for each component. (Σ ((number of functional groups of each component-1) × 2) × molecular weight of each component).

  Specific examples of such a rough surface forming layer 21 include urethane acrylate resins containing dipentaerythritol pentaacrylate having 5 functional groups as a monomer.

  By using such a rough surface forming layer 21, in an optical film having an optical functional layer and a base material layer, there is a problem of occurrence of interference fringes due to warpage and optical adhesion even in a high-temperature, high-temperature, high-humidity environment such as a vehicle. Can be solved. For example, it is not necessary to sandwich an optical functional layer between two base material layers using an additional base material layer, and the layer configuration can be simplified. That is, the base material layer can be only one layer.

Such an optical film 20 is produced as follows, for example.
First, the light transmission part 23 is formed on one surface of the base material layer 28. This inserts the base material sheet used as the base material layer 28 between the die roll which has the shape which can transfer the shape of the light transmission part 23 on the surface, and the nip roll arrange | positioned so as to oppose this. And a mold roll and a nip roll are rotated, supplying the composition which comprises a light transmissive part between a base material sheet and a mold roll. As a result, a groove corresponding to the light transmitting portion formed on the surface of the mold roll (a shape obtained by reversing the shape of the light transmitting portion) is filled with the composition that constitutes the light transmitting portion, and the composition becomes the surface of the mold roll. It will be along the shape.

  Here, examples of the composition constituting the light transmitting portion include ionizing radiation curable resins such as epoxy acrylate, urethane acrylate, polyether acrylate, polyester acrylate, and polythiol.

  Light for curing with a light irradiation device is irradiated from the substrate sheet side to the composition constituting the light transmission portion sandwiched between the mold roll and the substrate sheet and filled therein. Thereby, a composition can be hardened and the shape can be fixed. And the base material layer 28 and the shape | molded light transmission part 23 are released from a metal mold | die roll with a mold release roll.

  Next, the light absorption part 24 is formed. In order to form the light absorbing portion 24, first, the composition constituting the light absorbing portion is filled in the interval between the light transmitting portions 23 formed above. Thereafter, the surplus composition is scraped off with a doctor blade or the like. Then, the remaining composition is cured by irradiating light that cures the composition from the light transmitting portion 23 side to form the light absorbing portion 24.

  The material used as the light absorbing portion is not particularly limited, but is colored in a photocurable resin such as urethane (meth) acrylate, polyester (meth) acrylate, epoxy (meth) acrylate, and butadiene (meth) acrylate. And a composition in which the light absorbing particles are dispersed.

Further, instead of dispersing the light absorbing particles, the entire light absorbing portion can be colored with a pigment or a dye.
When using light-absorbing particles, light-absorbing colored particles such as carbon black are preferably used. However, the present invention is not limited to these, and the light-absorbing particles are matched to the characteristics of the light from the surface light source device and the image light to be emitted. Alternatively, colored particles that selectively absorb a specific wavelength may be used. Specific examples include organic fine particles colored with metal salts such as carbon black, graphite, and black iron oxide, dyes, pigments, colored glass beads, and the like. In particular, colored organic fine particles are preferably used from the viewpoints of cost, quality, availability, and the like. The average particle diameter of the colored particles is preferably 1.0 μm or more and 20 μm or less.

  Furthermore, the composition which comprises the rough surface formation layer 21 is apply | coated to the surface on the opposite side to the side in which the base material layer 28 is arrange | positioned among the optical function layers 22. Then, the composition is cured by an appropriate method in a state where the applied material is sandwiched between the roll mold for forming the rough surface 21a and the optical functional layer 22. Thereby, the sandwiched material is cured, and the rough surface forming layer 21 is formed.

  Examples of the functional layer 30 include known layers having various functions arranged on the viewer side from the liquid crystal panel. Examples thereof include an antireflection layer, an antiglare layer, and a hard coat layer.

  The video source unit 5 having the above-described configuration can be manufactured as follows, for example. That is, the produced optical film 20 is disposed on the light emitting side of the surface light source device 11 so that the rough surface 21a faces the surface light source device 11 side, and the liquid crystal panel 12 and the functional layer 30 are disposed on the viewer side of the optical film 20. Are laminated. At this time, since the rough surface forming layer 21 is configured as described above, the optical film 20 is less likely to warp, and can be easily combined with the surface light source device 11. Further, when the optical film 20 is overlaid on the surface light source device 11, the optical contact is prevented by the rough surface 21a, and the occurrence of interference fringes is also suppressed. Thus, even when high heat resistance and humidity resistance are required by the optical film 20 as in a vehicle, both the warpage and optical adhesion are good with a thin layer structure. In order to prevent warping, it is not necessary to stack a plurality of stiff base material layers, the layer configuration can be simplified, and the video display device can be made thinner.

  The video display unit 1 can be obtained by placing the video source unit 5 configured as described above in the housing 2 and arranging the functional layer 30 side to be an observer side. In that case, an electric circuit, a power supply circuit, etc. for operating the video source unit 5 are also provided if necessary.

  Such a video display device is disposed in the vehicle and operates, for example, as follows. This will be described with an example of the optical path. However, the optical path example is conceptual for explanation, and does not strictly represent reflection or refraction.

  When the image display device 1 is operated, projection illumination light is emitted from the surface light source device 11 as shown in FIG. The light L10 emitted from the surface light source device 11 passes through the optical film 20 without reaching the interface between the light transmission part 23 and the light absorption part 24, and obtains and transmits video information through the liquid crystal panel 12, and also passes through the functional layer 30. Then, the viewer can reach the viewer side and observe the image light.

  The light L11 emitted from the surface light source device 11 reaches the interface between the light transmission part 23 and the light absorption part 24, is totally reflected by the relationship between the refractive index difference between them and the incident angle to the interface, and is displayed on the liquid crystal panel 12 as video information. Is transmitted, and the functional layer 30 is also transmitted and emitted to the viewer side. At this time, since the interface between the light transmitting portion 23 and the light absorbing portion 24 is inclined as described above with respect to the normal line of the light exit surface of the optical film 20, the direction of the light L11 is changed downward. . This prevents reflection on the windshield. Further, since the light L11 is directed in the front direction, it contributes to the improvement of the front luminance of the image light.

  In this example, the optical film described above was laminated on a light source, and the warpage and optical adhesion were examined. Moreover, the optical film of the aspect which is not contained in the optical film demonstrated as a comparative example was also produced, and it evaluated similarly.

Example 1
The optical film of Example 1 (vertical direction 100 mm × horizontal direction 200 mm) had the following specifications. The direction in which the light transmission part and the light absorption part extend was the horizontal direction.
-Base material layer: Polycarbonate resin (Eiwa Co., Ltd.), thickness 130μm
-Light transmission part: UV curable urethane acrylate resin (Sanyo Chemical Industries, CR03)
Light absorption part: UV curable urethane acrylate resin containing 20% by mass of black beads with an average particle size of 4 μm (DNP Fine Chemical Co., Ltd., EL132)
The shape of the light absorption part: the long bottom base in the trapezoidal section is 9.4 μm, the short top base is 4.0 μm, the height (Dk in FIG. 3) is 102.0 μm, and the pitch of the adjacent light absorption parts (FIG. 3). Pk) is 39.0 μm
-Distance from the upper base of the light absorption part to the surface of the base material layer (Lk in FIG. 3): 25 μm
Rough surface forming layer: UV curable urethane acrylate resin (Sanyo Chemical Industries, BCP34), thickness 15 μm, rough surface roughness Ra = 0.2 μm, average cross-linking molecular weight (crosslinking density) = 561

Here, the rough surface roughness of the rough surface forming layer is a value measured at a surface magnification of 500 times using a laser microscope (Keyence Corporation, VK-8700). The average molecular weight between crosslinks of the rough surface forming layer was determined by the following formula.
Average molecular weight between crosslinks = total molecular weight / number of crosslinking points (total molecular weight: number of moles of each component x molecular weight of each component, number of crosslinking points = Σ <[(number of functional groups of each component-1) × 2] × Molecular weight of each component>)

  In Examples 2 to 5 and Comparative Examples 1 to 4, the thickness of the rough surface forming layer, the rough surface roughness of the rough surface forming layer, and the molecular weight between crosslinks of the material constituting the rough surface forming layer were changed. Specific values are shown in Table 1. The molecular weight between crosslinks was changed by changing the component ratio of the material constituting the rough surface forming layer.

The optical films of the examples and comparative examples shown above were evaluated for warpage and sticking (optical adhesion). Specific methods and evaluation criteria are as follows.
The warping was done by exposing the optical film to air at 105 ° C. and 0% humidity for 1000 hours in an air atmosphere, and then leaving it on a flat surface at room temperature and humidity for 24 hours. This was done by measuring. As a result, the case where the warpage was 5 mm or less was designated as “◯”, and the case where the warpage exceeded 5 mm was designated as “x”.
Sticking is performed by laminating the optical film of each example on a reflective polarizing sheet (3M Japan Co., Ltd.) and fixing it with a frame of plastic, stainless steel, etc., and in an air atmosphere at 105 ° C. and 0% humidity for 1000 hours. After being exposed and cooled to room temperature and normal humidity, illumination was performed from behind with a backlight and observed visually. The backlight of this example includes a reflective sheet, a light guide plate (a light source is disposed on the side surface), a diffusion sheet, a lens sheet, and a reflective polarizing sheet. As a result, “O” indicates that the pasted pattern is not visually recognized, and “X” indicates that the pasted pattern is viewed.
The results of evaluation are also shown in Table 1.

  As can be seen from Table 1, warping and sticking can both be made satisfactory by satisfying the above conditions.

DESCRIPTION OF SYMBOLS 1 Image display apparatus 5 Image source unit 10 Image source 11 Surface light source apparatus 12 Liquid crystal panel 20 Optical film 21 Rough surface formation layer 21a Rough surface 22 Optical functional layer 28 Base material layer

Claims (4)

An optical film having a plurality of layers,
A base material layer;
Stacked on one surface of the base material layer and capable of absorbing light between a plurality of light transmitting portions arranged along the layer surface of the base material layer so as to transmit light, and the adjacent light transmitting portions An optical functional layer having a light absorbing portion arranged;
A rough surface forming layer having a thickness of 15 μm or more and 25 μm or less laminated on the surface of the optical functional layer opposite to the side on which the base material layer is laminated,
The rough surface forming layer has a rough surface formed on the surface opposite to the optical functional layer, and the surface roughness of the rough surface is 0.1 μm or more and 0.2 μm or less in terms of Ra.
The material which comprises the said rough surface formation layer is an optical film whose crosslinking density is 320 or more and 740 or less resin.   The optical film according to claim 1, wherein the base material layer is made of polycarbonate.   An image source unit comprising a surface light source device, a liquid crystal panel, and the optical film according to claim 1, wherein the optical film is disposed between the surface light source device and the liquid crystal panel. A housing,
A video display device comprising: the video source unit according to claim 3 disposed inside the housing.

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