TW201910893A - Light emitting direction controlling sheet - Google Patents

Abstract

A light emitting direction controlling sheet, including a louver layer in which a light transmission band and a light shielding band are alternately arranged; a first transparent resin layer that is provided on a first side of the louver layer; and a second transparent resin layer that is provided on a second side of the louver layer, wherein the refractive index difference of the refractive index of the light transmission band and the refractive index of the first transparent resin layer is less than 0.1, and the refractive index difference of the refractive index of the light transmission band and the refractive index of the second transparent resin layer is less than 0.1.

Description

 Light transmission direction control sheet  

The present invention relates to a light transmission direction control sheet that transmits only light having a specific incident angle among incident light beams. More specifically, the present invention relates to a light transmission direction control sheet capable of realizing a narrow viewing angle when installed on illumination, display screens of various information display devices, and the like.

(Patent Document 1) discloses a sneak-proof body which is provided on a display screen of an information display device such as an action information terminal or an automatic depositing and dispensing machine, and can prevent the left and right sides from being damaged without damaging the visibility from the front side of the display screen. Peek on the opposite side. The anti-puncture body is formed into a three-layer structure in which the layers are laminated, that is, an anti-glare layer in which the light-transmitting belt and the light-shielding belt are alternately disposed, a translucent adhesive layer provided on one surface of the anti-glare layer, and a setting. a light transmissive layer on the other surface of the antiglare layer on the side opposite to the adhesive layer. The adhesive layer is pasted on the display screen of the information display device.

 [Prior Art Literature]    [Patent Literature]  

Patent Document 1: Japanese Patent No. 3675752

By incorporating the light transmission direction control sheet (anti-peeping body) into the inside of the mobile information terminal, it is necessary to improve user convenience. Since the light-transmitting layer provided in the anti-spy material of Patent Document 1 has a sufficient thickness for the purpose of improving the rigidity of the anti-peeping body, it is not suitable for use in a narrow terminal. When the light-transmitting layer of the above-described anti-puncture body is removed for the purpose of thinning, minute irregularities which are inevitably formed at the time of manufacture are exposed on the surface of the anti-glare layer. Since the light is reflected by the irregularities, the haze value becomes high, and the image transmitted through the anti-glare layer and the problem that the anti-glare layer itself cannot be clearly recognized cannot be clearly recognized.

When the anti-spying body is adhered to the display screen, it is possible to suppress the random reflection of the light. However, since it is difficult to see through (see through) the anti-peeping body before the bonding, it is difficult to perform the quality of the anti-peeping body. Check the problem.

Further, in the conventional anti-puncture body, since the refractive index of the transparent resin constituting the light-transmitting layer is different from the refractive index of the transparent resin constituting the anti-glare layer, there is a problem that the light transmittance is lowered due to the difference in refractive index. .

The present invention has been made in view of the above problems, and it is an object of the invention to provide a light transmission direction control sheet which has excellent light transmittance and can be visually inspected for quality.

[1] A light transmission direction control sheet comprising: a grid layer in which a light transmission belt and a light shielding tape are alternately arranged; a first transparent resin layer provided on a first surface of the grid layer; and a grid layer disposed on the grid layer a second transparent resin layer on the second surface, a difference between a refractive index of the light transmission band and a refractive index of the first transparent resin layer, and a refractive index of the light transmission band and a refractive index of the second transparent resin layer The difference is less than 0.1.

[2] The light transmission direction control sheet according to [1], wherein an arithmetic mean roughness Ra of an outer surface of at least one of an outer surface of the first transparent resin layer and an outer surface of the second transparent resin layer is 0 μm to 3.0 μm.

[3] The light transmission direction control sheet according to [1], wherein the light transmission belt, the first transparent resin layer, and the second transparent resin layer are formed of tantalum rubber.

[4] The light transmission direction control sheet according to [2], wherein the light transmission band, the first transparent resin layer, and the second transparent resin layer are formed of tantalum rubber.

[5] The light transmission direction control sheet according to any one of [1] to [4] wherein the thickness of the grid layer is 150 μm to 500 μm, and the thickness of the first transparent resin layer is 10 μm to 20 μm, The thickness of the second transparent resin layer is from 10 μm to 20 μm.

According to the light transmission direction control sheet of the present invention, since the interface reflection in the interface between the grid layer and the first and second transparent resin layers is lowered, the light transmittance is excellent. Thereby, it is possible to suppress a decrease in the brightness of the displayed display screen, and it is possible to obtain a sufficiently bright display screen even when a low backlight brightness is set. In addition, low power consumption of the backlight can be achieved. Further, since it has excellent light transmittance, it is possible to easily perform quality inspection by visual observation. Even when the light transmission direction control sheet of the present invention is made thinner, these excellent effects can be sufficiently exhibited, and therefore, it can be easily incorporated into the inside of the information display device.

1‧‧‧ Grid layer

2‧‧‧Light transmission belt

3‧‧‧Lighting tape

4‧‧‧First transparent resin layer

4a‧‧‧ outer surface of the first transparent resin layer

5‧‧‧Second transparent resin layer

5a‧‧‧ outer surface of the second transparent resin layer

10‧‧‧Light transmission direction control film

20‧‧‧Light transmission direction control film

21‧‧‧First transparent resin layer

22‧‧‧First grid layer

23‧‧‧ Third transparent resin layer

24‧‧‧Second grid layer

25‧‧‧Second transparent resin layer

26‧‧‧Light transmission belt

27‧‧‧Lighting tape

28‧‧‧Light transmission belt

29‧‧‧Lighting tape

Fig. 1 is a cross-sectional view showing an example of a light transmission direction control sheet of the present invention.

Fig. 2 is a perspective view showing another example of the light transmission direction control sheet of the present invention.

As shown in Fig. 1, the light transmission direction control sheet 10 of the present invention includes: a grid layer 1 in which the light transmission belt 2 and the light shielding tape 3 are alternately arranged; and a first transparent surface provided on the first surface of the grid layer 1 a resin layer 4; a second transparent resin layer 5 provided on the second surface of the grid layer 1.

Each of the light transmission bands 2 and the respective light shielding tapes 3 are formed along the thickness direction of the grating layer 1. In other words, the light transmission band 2 and the light shielding tape 3 are alternately arranged alternately in the width direction (the direction perpendicular to the thickness direction) of the grid layer 1. In the grid layer 1, light is transmitted through the light-transmitting belt 2 sandwiched between the light-shielding belts 3 in the thickness direction of the grid layer 1, that is, in the thickness direction of the light-transmitting direction control sheet 10.

In the light transmission direction control sheet 10, the first surface of the grid layer 1 supports the first main surface of the sheet, and the second surface of the grid layer 1 supports the second main surface of the sheet, the first side and the second side are each other Opposite face.

The size of the light transmission direction control sheet 10 is not particularly limited, and may be, for example, a size of a rectangle having a length of 1 mm to 1500 mm and a width of 1 mm to 1500 mm in plan view. The thickness of the light transmission direction control sheet 10 will be described later.

In the light transmission direction controlling sheet 10, the difference between the refractive index of the light transmitting belt 2 and the refractive index of the first transparent resin layer 4, and the difference between the refractive index of the light transmitting belt 2 and the refractive index of the second transparent resin layer 5 are respectively Less than 0.1. Here, the difference in refractive index is an absolute value.

In the present invention, "refractive index" is the refractive index of the member in a vacuum, and refers to an absolute refractive index. This refractive index is measured in accordance with the method A of JIS K 7142:2014 (ISO 489:1999) "Method for measuring plastic-refractive index".

The difference between the refractive index of the light transmitting strip 2 and the refractive index of the first transparent resin layer 4 is less than 0.1, preferably less than 0.01, and substantially less than zero, whereby the grid layer 1 and the first transparent The interface reflection at the interface of the resin layer 4 is lowered, and the light transmittance is improved. Similarly, the difference between the refractive index of the light transmitting belt 2 and the refractive index of the second transparent resin layer 5 is less than 0.1, preferably less than 0.05, more preferably less than 0.02, and most preferably substantially zero. The interface reflection at the interface between the grid layer 1 and the second transparent resin layer 5 is lowered, and the light transmittance is improved. As a result, the light transmission direction control sheet 10 has excellent light transmittance.

When the transparent resin layer is not provided and the surface of the grid layer 1 is exposed, since light scattering occurs on the exposed surface, it is difficult to visually confirm the light transmission band constituting the grid layer 1 through the grid layer 1. 2 and the case where the light shielding tape 3 is regularly arranged. On the other hand, by providing the first transparent resin layer 4 and the second transparent resin layer 5, the light transmitting direction control sheet 10 is observed, and it is possible to visually confirm that the light transmitting tape 2 and the light shielding tape 3 constituting the grating layer 1 have Regularly arranged. Thereby, quality management can be easily performed.

The arithmetic mean roughness Ra of the outer surface of at least one of the outer surface (outward facing surface) 4a of the first transparent resin layer 4 and the outer surface 5a of the second transparent resin layer 5 is preferably 0 μm to 3.0 μm. More preferably, it is from 0.0 μm to 0.5 μm, more preferably from 0.0 μm to 0.2 μm.

If it is within the above range, the outer surface has smoothness equivalent to the final processing of the mirror surface, and scattering of light on the outer surface can be further suppressed. Thus, it is easier to visually confirm that the light-transmitting belt 2 and the light-shielding belt 3 constituting the grid layer 1 are regularly arranged to pass through the first transparent resin layer 4 and the second transparent resin layer 5. In other words, quality management is easier. Further, optical characteristics such as light transmittance of the light transmission direction control sheet 10 can be improved.

In the present specification, the numerical range of the "lower limit value to the upper limit value" means a numerical value range of "the lower limit value or more and the upper limit value or less" unless otherwise specified.

From the viewpoint of improving the transparency of the light transmission direction control sheet 10, the arithmetic mean roughness (Ra) of the outer surfaces of both the outer surface 4a of the first transparent resin layer 4 and the outer surface 5a of the second transparent resin layer 5 is The above suitable range is preferred.

In the present invention, "arithmetic mean roughness (Ra)" is measured in accordance with JIS B 0601:2013 (ISO4287:1997) "Product Geometric Specifications".

 [Light transmission material]  

The material of the light transmitting belt 2 constituting the grid layer 1 is not particularly limited as long as it satisfies the relationship of the above refractive index, and is suitable, for example, for a resin having high transparency. Specifically, the light transmittance (light transmittance) when the light is transmitted through the width direction of the grid layer 1 is 75% or more, and the transparency is 85% or more, only the light transmission band 2 of the grid layer 1 is high. The resin material is preferred. Further, the upper limit of the light transmittance is not particularly limited, and may be, for example, 99.99% or less. As the resin material, for example, a thermoplastic resin or a thermosetting resin having high transparency can be used, and specific examples thereof include a cellulose resin, a polyolefin resin, a polyester resin, an anthracene resin, a polystyrene resin, and a polyvinyl chloride. Resin, acrylic resin, polycarbonate resin, and the like. Among them, enamel resin is preferred, and ruthenium rubber is particularly preferred in terms of heat resistance. The ruthenium rubber may be a composition containing a component other than ruthenium resin.

Examples of the ruthenium rubber include a ruthenium rubber composition generally composed of a kneaded rubber, and a diorganopolysiloxane having an end of a molecular chain terminated with a hydroxy fluorenyl group or an ethylene sulfhydryl group, and an organic peroxide; a diorganopolyoxy siloxane having at least two vinyl groups bonded to a ruthenium atom in a molecule, an organic hydrogen polyoxy siloxane having at least three hydrogen atoms (=SiH bond) bonded to a ruthenium atom in a mixed molecule, and platinum A so-called addition reaction type organic ruthenium rubber composition which is a catalyst.

 [Material of the light shielding tape]  

The material of the light-shielding tape 3 constituting the grid layer 1 is not particularly limited. For example, as the material of the light-transmitting tape 2, it is preferable to add a coloring agent such as a pigment or a dye to the above-mentioned resin as a base material. Colored resin. The resin material constituting the light transmitting belt 2 and the resin material as the base material of the light shielding tape 3 may be the same or different, but from the viewpoint of easy adhesion of the light transmitting tape 2 and the light shielding tape 3, The same resin material is preferred.

The color tone of the light-shielding tape 3 is sufficient as long as it can obtain sufficient light-shielding property, and examples thereof include black, red, yellow, green, blue, and light blue. The color tone and light blocking property of the light-shielding tape 3 can be adjusted by the kind and addition amount of a coloring agent. Specifically, it is preferable that the light-shielding tape 3 of the grid layer 1 has a light transmittance of 20% or less and preferably 5% or less when the light is irradiated in the thickness direction of the grid layer 1. The light transmittance can be 0%. Further, since the color tone of the light-shielding tape is the color tone recognized when the grid layer 1 is observed, it is preferable to carry out the design in consideration of the decorative property.

Specific examples of the colorant include general organic pigments or inorganic pigments such as carbon black, iron oxide, titanium oxide, yellow iron oxide, disazo yellow, and indigo blue. The coloring agent may be used singly or in combination of two or more. Further, in the case where a black pigment is not used, in order to obtain good light-shielding properties, it is preferred to use a white pigment in combination.

 [Light transmission tape and width of the light shielding tape]  

The width of the light transmission band 2 and the light shielding tape 3 (the thickness in the lateral direction of Fig. 1) can be freely set. The light transmittance of the grid layer 1 can be adjusted by the ratio of the width of the light transmission belt 2 / the width of the light shielding tape 3. The range of the viewing angle (visual angle) can be adjusted by the width of the light transmittance 2 and the thickness of the grid layer 1.

If it is considered that the peep prevention and the good visibility of the display screen coexist, the width of the light transmission band 2 is preferably 50 to 200 μm, more preferably 100 to 150 μm. Further, the width of the light-shielding tape 3 is preferably from 1 to 50 μm, more preferably from 10 to 30 μm. When the respective widths are adjusted to the above range, for example, the light transmission direction control sheet 10 having a light transmittance of 80% or more and a viewing angle of 30 to 120° can be obtained.

The ratio expressed by the width of the light-shielding tape 3 / the width of the light-transmitting tape 2 is preferably 0.005 to 1, more preferably 0.06 to 0.3.

 [Material of Transparent Resin Layer]  

The material of the first transparent resin layer 4 and the second transparent resin layer 5 is not particularly limited as long as it satisfies the relationship of the above refractive index. For example, the above resin is suitable as the material of the light transmission belt 2. A material having a light transmittance of 75% or more in the thickness direction of each transparent resin layer is preferable, and a material having a light transmittance of 85% or more is more preferable. The upper limit of the light transmittance is not particularly limited, and may be, for example, 99.99% or less.

Specific examples of the material of the transparent resin layer include a cellulose resin, a polyolefin resin (particularly a cycloolefin polymer), a polyester resin, an anthracene resin, a polystyrene resin, and a polyvinyl chloride. Resin, acrylic resin, polycarbonate resin, and the like. As a suitable enamel rubber, the above-mentioned light transmission belt is exemplified.

Among the above, a resin having a refractive index (1.0003) closer to that of a thermoplastic resin such as polycarbonate or PET (refractive index = 1.59 to 1.60) and having a small loss of light transmittance reflected by an interface (refractive index) It is preferable that the heat resistance is 矽 rubber (refractive index = 1.40 to 1.43). When the transparent resin layers 4 and 5 are ruthenium rubber, the adhesion between the outer surfaces 4a and 5a of the transparent resin layer is remarkably improved (adhesiveness can be brought about), so that the transparent resin layer can be closely attached to the display screen. The surface is thus able to easily set the light transmission direction control sheet 10.

The resin constituting each of the transparent resin layers may contain a known additive in the field of a resin film such as an ultraviolet absorber, an infrared ray absorbing agent, or a coloring agent, for the purpose of improving weather resistance and designing properties, as needed.

The material of the first transparent resin layer 4 and the material of the second transparent resin layer 5 may be the same or different, but from the viewpoint of easily satisfying the relationship of the above refractive index, it is preferable that the materials are the same. Further, from the same viewpoint, the materials of the first transparent resin layer 4 and the second transparent resin layer 5 are preferably the same as those of the light transmitting tape 2 of the grid layer 1.

 [thickness of each layer]  

Preferably, the thickness of the grid layer 1 is preferably from 100 μm to 5000 μm, more preferably from 150 μm to 1000 μm, still more preferably from 150 μm to 500 μm. When the thickness of the grid layer 1 is in the above range, the control of the viewing angle (visual angle) becomes easy.

The thicknesses of the first transparent resin layer 4 and the second transparent resin layer 5 are each independent, preferably 1 μm to 100 μm, more preferably 5 μm to 50 μm, still more preferably 10 μm to 20 μm. When the thicknesses of the first transparent resin layer 4 and the second transparent resin layer 5 are within the above ranges, the balance between the rigidity and the thickness of the light transmission direction control sheet 10 can be obtained.

The total thickness of the grid layer 1, the first transparent resin layer 4, and the second transparent resin layer 5 is preferably 100 μm to 5200 μm, more preferably 150 μm to 1200 μm, still more preferably 200 μm to 700 μm.

When the total thickness of each layer is equal to or greater than the lower limit of the above range, the rigidity of the light transmission direction control sheet 10 is increased, the operability at the time of setting in the vicinity of the display screen of the information display device is improved, and the control of the viewing angle (visual angle) is changed. It's easy.

When the total thickness of each layer is equal to or less than the upper limit of the above range, the thinning of the light transmission direction control sheet 10 can be sufficiently achieved, and it becomes easy to fit inside the information display device.

In addition, in the present specification, the "thickness" is a value obtained by observing a cross section of a measurement object using a microscope, measuring the thickness at five places, and averaging them.

 [arbitrary transparent member]  

Any transparent member such as a transparent layer or a transparent film may be provided on at least one of the outer surface 4a of the first transparent resin layer 4 and the outer surface 5a of the second transparent resin layer 5, for example, a known adhesive layer or adhesive layer. , transparent film, protective sheet, etc.

Examples of the material of the adhesive layer include an elastomer-based adhesive, an acrylic adhesive, a polyurethane adhesive, and a rubber adhesive. Examples of the elastomer-based adhesive include an adhesive such as ruthenium rubber, ruthenium gel, polyurethane rubber, or polyurethane gel. When an elastomer-based adhesive is used, in order to improve the transparency, it is preferred to perform a known mirror finish on the surface of the adhesive layer.

From the viewpoint of excellent optical characteristics of the light transmission direction control sheet 10, the refractive index of the transparent member such as any of the transparent layer and the transparent film, and the light transmitting tape 2, the first transparent resin layer 4, and the second transparent resin layer 5 are The difference in refractive index of each constituent material is preferably less than 0.1, more preferably less than 0.02, and substantially zero and more preferably.

In addition, from the viewpoint of making the optical characteristics of the light transmission direction control sheet 10 excellent and simplifying the sheet structure, the other transparent members are not provided on the outer surfaces of the first transparent resin layer 4 and the second transparent resin layer 5. It is better.

 [Manufacturing method of light transmission direction control sheet]  

The grid layer 1 constituting the light transmission direction control sheet 10 can be manufactured, for example, by the following method. First, a plurality of first sheets of a desired thickness composed of a constituent material of the light-transmitting belt 2, and a plurality of second sheets of a desired thickness composed of constituent materials of the light-shielding belt 3 are alternately laminated and heated and pressurized. Thereby, a block body in which the plurality of sheets are integrally formed is formed.

Next, the grid layer 1 is obtained by slicing the block on a section perpendicular to the surface of the sheet. The thickness (slice width) at the time of slicing corresponds to the thickness of the grid layer 1. By slicing the block on the surface inclined with respect to the surface of the sheet, the angle formed by the surface of the grid layer 1 and the light shielding tape 3 can be adjusted.

The method of laminating the grid layer 1 and the respective transparent resin layers 4 and 5 so as to be integrated is not particularly limited, and a known method can be suitably used.

As an example, a method of forming the first transparent resin layer 4 by coating a material forming the first transparent resin layer 4 on the first surface of the grid layer 1 and curing it is exemplified. The second transparent resin layer 5 can be formed on the second surface of the grid layer 1 by the same method.

By laminating the grid layer 1 and the respective transparent resin layers 4 and 5, the integrated laminate is formed into a desired shape, whereby the light transmission direction control sheet 10 can be obtained. The planar shape of the light transmission direction control sheet 10 is not particularly limited, and a shape such as a rectangle, a polygon, a circle, or an ellipse may be appropriately used to match the shape of the displayed display screen.

In the above, the case where the light transmission direction control sheet of the present invention has one grid layer will be described. The light transmission direction control sheet of the present invention may have two layers of grid layers. Hereinafter, a configuration of the light transmission direction control sheet 20 in which two layers of the grid layers are laminated will be described with reference to Fig. 2 .

Fig. 2 is a perspective view schematically showing a part of the light transmission direction control sheet 20 and schematically shown. In the second drawing, the thickness direction of the light transmission direction control sheet 20 is set to the Z direction, and the light source side of the light incident on the sheet 20 is the Z1 side, and the irradiation side (recognition side) through which the light of the sheet 20 is emitted is emitted. For the Z2 side. Further, two directions perpendicular to each other in the plane perpendicular to the Z direction are referred to as an X direction and a Y direction, respectively.

The light transmission direction control sheet 20 laminates the first transparent resin layer 21, the first grid layer 22, the third transparent resin layer 23, the second grid layer 24, and the second transparent resin layer in this order from the Z1 side in the thickness direction. 25, thereby forming an integration with each other.

The first transparent resin layer 21 is disposed on the surface (first surface) on the Z1 side of the first grid layer 22, and the second transparent resin layer 25 is disposed on the surface (second surface) on the Z2 side of the second grid layer 24, The third transparent resin layer 23 is provided on the surface (second surface) on the Z2 side of the first grid layer 22, that is, on the surface (first surface) on the Z1 side of the second grid layer 24.

The overall planar shape of the light transmission direction control piece in the X-Y plane (the surface perpendicular to the Z direction) is, for example, a rectangle, but may be appropriately changed depending on the shape of the installation.

In the light transmission direction control sheet 20, the difference between the refractive index of the light transmission band 26 and the refractive index of the first transparent resin layer 22, the difference between the refractive index of the light transmission band 26 and the refractive index of the third transparent resin layer 23, The difference in refractive index between the three transparent resin layers 23 and the light transmitting belt 28 and the difference between the refractive index of the light transmitting belt 28 and the refractive index of the second transparent resin layer 25 are each less than 0.1. Here, the difference in refractive index is an absolute value.

In the first grid layer 22, the light transmitting belt 26 and the light shielding belt 27 are alternately alternated in the Y direction. The light transmission belt 26 and the light shielding belt 27 are both strip-shaped in the X direction, and the widths in the Y direction are uniform and constant, respectively. The plurality of light transmission bands 26 have the same width and the plurality of light shielding bands 27 have the same width.

In the second grid layer 24, the light transmitting belt 28 and the light shielding belt 29 are alternately alternated in the X direction. The light transmission band 28 and the light shielding tape 29 are both strip-like shapes extending in the Y direction, and the widths in the X direction are uniform and constant, respectively. The plurality of light transmission bands 28 have the same width and the plurality of light shielding bands 29 have the same width.

In the light transmission direction control sheet 20 shown in Fig. 2, the angles of the light shielding bands of the respective grid layers 22 and 24 laminated by the two layers are set to be approximately 90° with each other when viewed in a plan view. Here, the above-mentioned included angle may be an angle other than 90°, or may be any angle selected from 0 to 90°. The thickness of the first grid layer 22 and the second grid layer 24 and the thickness of the light transmission band and the light shielding tape of each grid layer are independently set and may be the same as or different from each other.

In the light transmission direction control sheet 20 of Fig. 2, the two light transmission direction control sheets 10 of Fig. 1 are stacked in two layers, and the third transparent resin layer 23 is shared by the light transmission direction control sheets 10 on the upper side and the lower side. Composition. Since the difference in refractive index between each of the grid layers 22 and 24 and each of the transparent resin layers 21, 23, and 25 is as described above, the interface reflection at the interface between each of the grid layers and the respective transparent resin layers is lowered, and the light transmittance is improved. . As a result, the light transmission direction control sheet 20 has excellent light transmittance. Further, in the light transmission direction control sheet 20, the first grid layer 22 controls the angle of view in the Y direction, and the second grid layer 24 controls the angle of view in the X direction, and therefore, it is possible to control the sheet 20 by a light transmission direction. Simultaneously control the viewing angle in both directions.

The method for producing the light transmission direction control sheet 20 is not particularly limited as long as the grid layers 22 and 24 and the transparent resin layers 21, 23 and 25 are laminated and integrated. For example, the first transparent resin layer 21 is formed by coating a material forming the first transparent resin layer 21 on the first surface of the first grid layer 22 and curing it. Thereafter, a curable material forming the third transparent resin layer 23 is applied to the second surface of the first grid layer 22, and the second grid layer 24 is placed on the coating film before the complete curing to cure the coating film. Thereby, the third transparent resin layer 23 can be formed, and the first grid layer 22 and the second grid layer 24 are bonded by the third transparent resin layer 23. Next, similarly to the formation of the first transparent resin layer 21, the second transparent resin layer 25 is formed on the second surface of the second grid layer 24, whereby the light transmission direction control sheet 20 can be obtained.

 [Use of light transmission direction control sheet]  

By providing the light transmission direction control sheet 10 so as to cover the display screen in the vicinity of the display screen of the information display device, it is possible to prevent so-called peek. As an installation method, for example, the outer surface 4a of the first transparent resin layer 4 or the outer surface 5a of the second transparent resin layer 5 of the light transmission direction control sheet 10 formed into a rectangular shape is closely attached to the display constituting the information display device. The method of setting the transparent substrate of the screen. The light transmission direction control sheet 10 may be provided on the outer surface of the device to be exposed to the outside, or may be provided inside the device to be difficult to recognize from the outside. In the case where the light transmission direction control sheet 10 is incorporated in the inside of the information display device, for example, it is preferable that the outer surface 4a of the first transparent resin layer 4 is in close contact with and fixed to the transparent substrate constituting the display screen inside the device, The outer surface 5a of the second transparent resin layer 5 is in close contact with and fixed to the transparent substrate constituting the outer surface of the device (a part of the case). In other words, it is preferable to provide the light transmission direction control sheet 10 in a state of being closely attached to and sandwiched between the two transparent substrates which are separated from each other and which are provided by the information display device. When it is installed in this way, since the air layer is not interposed between the two transparent substrates of the information display device and the transparent resin layers 4 and 5 of the light transmission direction control sheet 10, the decrease in the light transmittance can be suppressed.

The extending direction of the light transmission band 2 (and the light shielding tape 3) of the light transmission direction control sheet 10 and the side of the display screen frame may or may not be parallel. In order to prevent the occurrence of moiré, the direction in which the light transmission band 2 is extended may be inclined with respect to the display frame (the skew angle may be increased).

As described above, the light transmission direction control sheet 10 will be described as a method of using the light transmission direction control sheet of the present invention, and the light transmission direction control sheet 20 may be used in the same manner as described above.

 [Examples]  

The examples are enumerated below, but the invention is not limited by the examples.

 [Example 1]  

The light transmission direction control sheet 10 shown in Fig. 1 was produced.

First, a first sheet having a thickness of 125 μm composed of a transparent tantalum rubber (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KE-153-U) having a refractive index of about 1.43 was prepared as a material of the light-transmitting belt 2.

In addition, a second sheet having a thickness of 10 μm composed of a material in which 15 parts by mass of carbon black is added to 100 parts by mass of a transparent enamel rubber (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KE-153-U) is prepared as a shading With 3 materials.

A plurality of first sheets and a plurality of second sheets are alternately laminated, and are heated, vulcanized, and pressurized to form a block in which the plurality of sheets are integrally formed.

The grid layer 1 was obtained by cutting a block into a sheet having a thickness of 310 μm in a cross section perpendicular to the surface of the sheet.

Since the surface of the grid layer 1 is roughened by slicing, a disordered reflection of light is generated on the surface, which is blurred. Therefore, it is difficult to observe through the individual grid layers 1, and it is not possible to visually confirm whether or not the light-transmitting belt 2 and the light-shielding belt 3 are regularly arranged.

Next, a liquid ruthenium rubber having a refractive index of about 1.43 was applied to the surface of the PET film subjected to the mirror processing using a screen printing machine at a thickness of about 20 μm (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KE-1987). The coated surface is placed on the first surface of the grid layer 1 and is vulcanized by heat vulcanization. Thereafter, the first transparent resin layer 4 composed of ruthenium rubber was formed by peeling off the PET film. By the same method, the second transparent resin layer 5 made of ruthenium rubber is formed on the second surface of the grid layer 1, whereby the light transmission direction control sheet 10 is obtained.

The light transmitting direction control sheet 10 before peeling off the PET film is visually observed, and the light transmitting tape 2 and the light shielding tape 3 constituting the grating layer 1 are regularly arranged, and it can be easily confirmed that this is a good product without defects.

Further, when there is a defect, it is possible to easily confirm irregular distribution of black spots or white spots by visual observation.

The arithmetic mean value of the outer surfaces of the respective transparent resin layers 4 and 5 of the light transmission direction control sheet 10 obtained by peeling off the PET film was measured using a surface roughness measuring instrument (manufactured by Kosaka Research Institute Co., Ltd., trade name: SE600). (Ra), the Ra of both surfaces was 0.1 μm, and both were the same smooth mirror surface as the surface of the mirror-finished PET film.

The light transmittance of the light transmission direction control sheet 10 was measured using a haze meter (manufactured by Nippon Denshi Kogyo Co., Ltd., trade name: NDH2000), and the total light transmittance was 80%, and the haze was 3. Here, the haze is obtained by the formula "haze (%) = Td / Tt × 100". In the formula, Td represents the diffuse transmittance, and Tt represents the total light transmittance.

The angle of view of the light transmission direction control sheet 10 is about 65° on a plane perpendicular to the longitudinal direction of the light transmission belt 2 and the light shielding belt 3 on which the grid layer 1 is extended.

 [Embodiment 2]  

A light transmission direction control sheet 10' was produced in the same manner as in Example 1 except that the rough-faced PET film was used.

The light transmitting direction control sheet 10' before peeling off the PET film is visually observed, and the light transmitting tape 2 and the light shielding tape 3 constituting the grating layer 1 are regularly arranged, and it can be easily confirmed that this is a good product without defects.

Further, when there is a defect, it is possible to easily confirm irregular distribution of black spots or white spots by visual observation.

In the same manner as in the first embodiment, the arithmetic mean roughness (Ra) and light transmittance of the outer surfaces of the transparent resin layers 4 and 5 of the light transmission direction control sheet 10' of the second embodiment obtained by peeling off the PET film were The haze and the viewing angle were measured, Ra = 2.6 μm, total light transmittance = 73%, haze = 41, and viewing angle = about 65 °. Compared with Example 1, the haze value was high and the total light transmittance was lowered.

 [Example 3]  

A light transmission direction control sheet 10" was produced in the same manner as in Example 1 except that a PET film which was not subjected to mirror processing was used.

By visually observing the light transmission direction control sheet 10" before peeling off the PET film, the light transmission tape 2 and the light shielding tape 3 constituting the grid layer 1 are regularly arranged, and it can be easily confirmed that this is a good product without defects.

Further, when there is a defect, it is possible to easily confirm irregular distribution of black spots or white spots by visual observation.

In the same manner as in the first embodiment, the arithmetic mean roughness (Ra) and light transmittance of the outer surfaces of the transparent resin layers 4 and 5 of the light transmission direction control sheet 10" of the third embodiment obtained by peeling off the PET film were The haze and the viewing angle were measured, Ra = 0.2 μm, total light transmittance = 78%, haze = 6, and viewing angle = about 65 °.

 [Comparative Example 1]  

An epoxy-based adhesive having a thickness of 10 μm (refractive index: about 1.55) was applied to both sides of the grid layer 1 produced in Example 1, and the outer surface was respectively mirror-coated by the adhesive layer of each surface. A processed polycarbonate film having a thickness of 30 μm (refractive index: about 1.58).

Through the above steps, a light transmission direction control sheet of a comparative example was obtained, which was provided with an adhesive layer and a polycarbonate film on each of both sides of the grid layer 1.

By visually observing the light-transmitting direction control sheet having a polycarbonate film on both sides, the light-transmitting tape 2 and the light-shielding tape 3 constituting the grid layer 1 are regularly arranged, and it is possible to easily confirm that there is no defect. The best.

Further, when there is a defect, it is possible to easily confirm irregular distribution of black spots or white spots by visual observation.

However, as shown in the results below, when compared with the light transmission direction control sheet 10 of the first embodiment, the optical characteristics are deteriorated. For this reason, it is conceivable that large interface reflection occurs at each interface of the grid layer 1, the adhesive layer, and the polycarbonate film.

In the same manner as in Example 1, the arithmetic mean roughness (Ra), light transmittance, haze, and viewing angle of the outer surface of each polycarbonate film of the light transmission direction control sheet of Comparative Example 1 were measured, and Ra = 0.1 μm. , total light transmittance = 77%, haze = 6, viewing angle = about 65 °.

Compared with Example 1, the haze value was high and the total light transmittance was lowered.

 [Comparative Example 2]  

A light transmission direction control sheet was produced in the same manner as in Comparative Example 1, except that a matte processed polycarbonate film (refractive index: about 1.58) was used.

By visually observing the light-transmitting direction control sheet having a polycarbonate film on both sides, the light-transmitting tape 2 and the light-shielding tape 3 constituting the grid layer 1 are regularly arranged, and it is possible to easily confirm that there is no defect. The best.

Further, when there is a defect, it is possible to easily confirm irregular distribution of black spots or white spots by visual observation.

However, as shown in the results of Table 1, the optical characteristics were deteriorated as compared with the light transmission direction controlling sheet 10 of Example 1. For this reason, it is conceivable that large interface reflection occurs at each interface of the grid layer 1, the adhesive layer, and the polycarbonate film.

The results of Examples 1 to 3 and Comparative Examples 1 to 2 are shown below. In Table 1, "the difference in refractive index" means, in the embodiment, the difference between the refractive index of the light transmission band (1.43) and the refractive index of the first transparent resin layer (1.43), and in the comparative example, the light transmission band The difference between the refractive index (1.43) and the refractive index of the epoxy-based adhesive (1.55). Further, "Ra" means, in the examples, the arithmetic mean roughness of the outer surface of the first transparent resin layer, and in the comparative example, the arithmetic mean roughness of the outer surface of the polycarbonate film.

According to the results of Table 1, the lower the arithmetic mean roughness Ra of the outer surface of the light transmission direction control sheet, the higher the optical characteristics. Further, from the results of Example 1 and Comparative Example 1 in which Ra is the same, it is understood that the optical characteristics are improved when the difference in refractive index is less than 0.1.

The present invention has been described above by way of specific examples, but the technical scope of the present invention is not limited by the scope described in the above embodiments. It will be apparent to those skilled in the art that various changes and modifications can be made to the above-described embodiments. In addition, it is obvious that such a modification or improvement is also included in the technical scope of the present invention in accordance with the description of the scope of the patent application.

 [Industrial availability]  

The light transmission direction control sheet of the present invention can be used, for example, as a sheet for preventing peeping on a display screen of various information display devices, or can be used as a filter in an illumination device or a sensor device.

Claims (5)

 A light transmission direction control sheet comprising: a grid layer, which is repeatedly provided with a light transmission belt and a light shielding strip; a first transparent resin layer disposed on the first surface of the grid layer; and a second transparent resin layer disposed on a difference between a refractive index of the light transmitting tape and a refractive index of the first transparent resin layer, and a difference between a refractive index of the light transmitting tape and a refractive index of the second transparent resin layer, respectively, of the second surface of the grating layer Less than 0.1.    The light transmission direction control sheet according to claim 1, wherein an outer surface of at least one of the first transparent resin layer and the second transparent resin layer has an arithmetic mean roughness Ra of from 0 μm to 3.0 μm. .    The light transmission direction control sheet according to claim 1, wherein the light transmission belt, the first transparent resin layer, and the second transparent resin layer are formed of tantalum rubber.    The light transmission direction control sheet according to claim 2, wherein the light transmission belt, the first transparent resin layer, and the second transparent resin layer are formed of tantalum rubber.    The light transmission direction control sheet according to any one of claims 1 to 4, wherein the thickness of the grid layer is 150 μm to 500 μm, and the thickness of the first transparent resin layer is 10 μm to 20 μm. The thickness of the two transparent resin layers is from 10 μm to 20 μm.