JP7253361B2 - VIEWING ANGLE CONTROL SHEET, VIEWING ANGLE CONTROL METHOD, DISPLAY AND MANUFACTURING METHOD THEREOF - Google Patents

Description

The present invention relates to a viewing angle control sheet capable of controlling a viewing angle when installed on a display screen of an information terminal or the like.

As an example of the viewing angle control sheet, Patent Document 1 proposes a sheet including a louver layer in which light transmission bands and light shielding bands are alternately arranged, and a transparent resin layer attached to both sides of the louver layer. Normally, when the pitch of the light-shielding bands of the louver layer (hereinafter referred to as louver pitch) is close to the repetition pitch of pixels on the display screen (hereinafter referred to as pixel pitch), there is a problem of interference fringes (moire). In order to suppress the visual recognition of interference fringes, it has been proposed to make the louver pitch much smaller than the pixel pitch, or to make the bias angle large so that the relative orientations of the periodic structures are not aligned (Patent Reference 2).

JP 2017-146359 A Japanese Patent No. 4968664

If the bias angle is increased as proposed in Patent Document 2, the direction of viewing angle control is greatly tilted (rotated) with respect to the vertical and horizontal sides of the screen, and the original purpose of viewing angle control is not achieved. can become difficult. In this case, a policy of making the louver pitch much smaller than the pixel pitch is adopted.
However, the pixel pitch of display devices such as liquid crystal displays (LCDs) and organic ELs is becoming more and more precise. The pixel pitch of a smartphone's full HD LCD is 0.06 mm. In order to suppress the visibility of interference fringes by attaching a viewing angle control sheet to a display screen with such a high-definition pixel pitch, it is necessary to reduce the louver pitch to about 0.04 mm. However, the production of viewing angle control sheets having such a louver pitch requires a high level of technology, which raises the problem of increased production costs.

The present invention provides a viewing angle control sheet capable of suppressing visual recognition of interference fringes by attaching it to a high-definition display screen.

[1] A viewing angle control sheet attached to a display screen of a display device having a pixel pitch of 0.15 mm or less, comprising a louver layer in which light transmission bands and light blocking bands are alternately and repeatedly arranged, A viewing angle control sheet, wherein the band pitch is 1.25 times or more the pixel pitch.
[2] The viewing angle control sheet according to [1], wherein the angle formed by the direction of the pitch of the light-shielding bands and the direction of the pixel pitch is 20° or less in plan view with respect to the display screen.
[3] A viewing angle control sheet having a louver layer in which light transmission bands and light shielding bands are alternately arranged is attached to the display screen of a display device having a pixel pitch of 0.15 mm or less, and the viewing angle of the display screen is adjusted. A viewing angle control method for controlling an angle, wherein the pitch of the light shielding band is 1.25 times or more the pixel pitch.
[4] The viewing angle control method according to [3], wherein an angle formed by the direction of the pitch of the light-shielding bands and the direction of the pixel pitch is 20° or less in plan view with respect to the display screen.
[5] A display device comprising: a display device main body having a display screen having a pixel pitch of 0.15 mm or less; and a viewing angle control sheet attached to the display screen, wherein the viewing angle control sheet A display device comprising a louver layer in which transmission bands and light-shielding bands are alternately arranged, wherein the pitch of the light-shielding bands is 1.25 times or more the pixel pitch.
[6] The display device according to [5], wherein the angle formed by the direction of the pitch of the light-shielding bands and the direction of the pixel pitch is 20° or less in plan view with respect to the display screen.
[7] A method of manufacturing a display device comprising a step of attaching a viewing angle control sheet to a display screen, wherein the display screen has a pixel pitch of 0.15 mm or less, and the viewing angle control sheet comprises a light transmission band and a light blocking sheet. 1. A method of manufacturing a display device, comprising a louver layer in which strips are alternately arranged, and wherein the pitch of the light-shielding strips is 1.25 times or more the pixel pitch.
[8] The method of manufacturing a display device according to [7], wherein an angle formed by the direction of the pitch of the light-shielding bands and the direction of the pixel pitch in plan view with respect to the display screen is 20° or less.

The viewing angle control sheet of the present invention can suppress the visual recognition of interference fringes by attaching it to a high-definition display screen.

1 is a perspective view showing an example of a viewing angle control sheet according to the present invention; FIG. FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1; FIG. 3 is a schematic diagram illustrating an example of an angle (bias angle) δ between the pixel pitch direction (x-axis direction) of the display screen D and the louver pitch direction (arrow L) of the viewing angle control sheet. FIG. 4 is a cross-sectional view in the thickness direction of another example of the viewing angle control sheet according to the present invention; FIG. 4 is a perspective view showing still another example of the viewing angle control sheet according to the present invention;

Hereinafter, a detailed description will be given with reference to the drawings, but the dimensions in the drawings are different from the actual ones for convenience of description. Further, in the present specification, the numerical range of "lower limit to upper limit" means a numerical range of "more than the lower limit and less than the upper limit", unless otherwise specified. In the present specification, the "thickness" is the average value obtained by observing the cross section of the object to be measured using a magnifying observation means such as a digital microscope, measuring the thickness at five randomly selected points, and averaging the thickness. .

≪Viewing angle control sheet≫
As shown in FIGS. 1 and 2, the viewing angle control sheet 10 of the first aspect of the present invention comprises a louver layer 1 in which light transmission bands 2 and light shielding bands 3 are alternately provided, and a louver layer 1 and a base layer 5 provided on the second surface of the louver layer 1. The first surface and the second surface of the louver layer 1 are surfaces facing each other.

Although the size of the viewing angle control sheet 10 is not particularly limited, for example, it may be rectangular with a length of about 10 mm to 100 cm and a width of about 10 mm to 100 cm in plan view. The combined thickness of the viewing angle control sheet 10, including the protective layer 4, the louver layer 1 and the base layer 5, can be, for example, about 500 μm to 5 mm.

[Louver layer 1]
The thickness direction of the viewing angle control sheet 10 is the Z direction, the direction in which the light transmission band 2 and the light shielding band 3 extend in the plane perpendicular to the Z direction is the X direction, and the direction perpendicular to both the X and Z directions is the direction. Let the direction be the Y direction. Both the light transmission bands 2 and the light shielding bands 3 that constitute the louver layer 1 are belt-shaped extending in the X direction, and the plurality of light transmission bands 2 and the plurality of light shielding bands 3 are alternately arranged in the Y direction. . The widths of the plurality of light transmission bands 2 in the Y direction are uniform and constant in the X direction. The Y-direction widths of the plurality of light-shielding bands 3 are also uniform and constant in the X-direction.

Each light transmitting zone 2 and each light shielding zone 3 of the louver layer 1 are belt-shaped portions penetrating in the Z direction. Light passes through the light transmission zone 2 along the Z direction. θ in FIG. 2 represents the range of viewing angles (visible angles) through which light can pass.

(Width of light transmission band and light shielding band)
The viewing angle control sheet 10 is a viewing angle control sheet to be attached to the display screen of a display device having a pixel pitch of 0.15 mm (150 μm) or less.
The pitch of the light-shielding band 3 (louver pitch) is the repetition period of the width of the light-transmitting band 2 and the width of the light-shielding band 3. When viewed in the Y direction in FIG. The sum of the widths of one light-shielding band 3 adjacent to 2 is the louver pitch. Reference P1 in FIG. 2 represents the louver pitch.
The direction of the louver pitch is the direction of the repeating cycle of the light transmission band 2 and the light shielding band 3 (the Y direction in FIGS. 1 and 2), and is perpendicular to the longitudinal direction of the light transmission band 2 and the light shielding band 3. be.

The louver pitch of the viewing angle control sheet 10 is 1.25 times or more the pixel pitch of the display screen to which it is attached. With this configuration, since the difference between the louver pitch and the pixel pitch is increased, it is possible to suppress the interference fringes from being visually recognized.

The pixel pitch is the period at which the pixels arranged on or within the display screen are repeated. A single pixel in a general display device using liquid crystal or organic EL is composed of a combination of two or more bright spots selected from red, blue, green, and white against a black background. Since the arrangement of pixels when the display screen is viewed in plan can be regarded as a two-dimensional lattice of an xy orthogonal coordinate system, the display screen has two pixel pitches that are orthogonal to each other.
The direction of the pixel pitch is the direction of the period in which the pixels are repeated. In the xy orthogonal coordinate system, if the direction of the first pixel pitch is the x-axis direction, the direction of the second pixel pitch is the y-axis direction. The directions of the two pixel pitches in a general display device often coincide with the horizontal direction and the vertical direction of the display screen, respectively.

In the present invention, the pixel pitch to be compared with the louver pitch is, of the above two pixel pitches, the direction of the pitch (repetition cycle) in the direction where the angle (bias angle) formed with respect to the direction of the louver pitch is less than 45°. be. FIG. 3 illustrates the directions of the louver pitch and the pixel pitch. In the xy orthogonal coordinates of FIG. 3, the direction of the first pixel pitch of the display screen D is the x-axis direction, and the direction of the second pixel pitch is the y-axis direction. The direction of the louver pitch of the viewing angle control sheet 10 attached to the display screen D (corresponding to the Y direction in FIG. 2) is indicated by an arrow L. As shown in FIG. The angle (bias angle) δ between the direction of the first pixel pitch and the direction of the louver pitch is less than 45°. On the other hand, the angle (90°-δ) between the direction of the second pixel pitch and the direction of the louver pitch is greater than 45°. Therefore, the pixel pitch compared to the louver pitch in this example is the first pixel pitch. As another example, the viewing angle control sheet 10 is arranged so that the angle δ′ formed by the direction of the louver pitch (corresponding to the Y direction in FIG. 2) and the direction of the second pixel pitch is less than 45°. When installed on a display screen, the pixel pitch to be compared with the louver pitch is the second pixel pitch.

In general, when the angle (bias angle) formed by the louver pitch direction and the pixel pitch direction is small, the interference fringes are easily visible. Even if the angle is set to 20° or less, it is possible to suppress the interference fringes from being visually recognized.
When the direction of the pixel pitch of the display screen is the direction of the horizontal axis of the screen, if the bias angle is reduced to about 0 to 20°, the longitudinal direction of the light shielding band 3 of the viewing angle control sheet with respect to the horizontal axis of the display screen. can be set up to nearly 70 to 90 degrees. That is, the smaller the bias angle, the smaller the angle formed between the longitudinal direction of the light shielding band 3 and the vertical axis direction of the display screen. As a result, it is possible to easily control the viewing angle .theta. of the display screen seen through the viewing angle control sheet, and to easily prevent peeking from the side of the front of the screen.

The range of the viewing angle θ is adjusted by the width of the light transmission zone 2 and the thickness of the louver layer 1 .
On the premise that the louver pitch is 1.25 times or more the pixel pitch of the display screen to which it is attached, the width of the light transmission zone 2 is 0.25 times or more, and considering both viewing angle control and good visibility of the display screen. 040 mm to 0.200 mm is preferred, and 0.080 mm to 0.190 mm is more preferred. The width of the light shielding band 3 is preferably 0.001 mm to 0.050 mm, more preferably 0.010 mm to 0.030 mm. By adjusting each width within the above range, for example, a viewing angle control sheet 10 having a light transmittance of 65% or more and a viewing angle θ of 30 to 120° can be obtained.

The thickness of the louver layer 1 is preferably 0.100 mm to 5.000 mm, more preferably 0.150 mm to 2.000 mm, even more preferably 0.200 mm to 1.000 mm. When the thickness of the louver layer 1 is within the above range, the viewing angle θ can be easily controlled.

As a specific example, when the viewing angle control sheet 10 is attached to a smartphone equipped with a full HD 5.5-inch display screen with a pixel pitch of 0.06 mm, the louver pitch is 0.075 mm or more (0.06 mm × 1.25 or more). is. Here, it is assumed that the width of the light blocking band 3 is 0.015 mm. If the louver pitch is set to 0.075 mm and the viewing angle θ is set to 40°, the thickness of the louver layer is 0.24 mm. is 0.10 mm. If the louver pitch is set to 0.110 mm and the viewing angle θ is set to 40°, the thickness of the louver layer is 0.38 mm. is 0.16 mm.

As another specific example, when the viewing angle control sheet 10 is attached to a high-definition notebook PC equipped with a full HD 12-inch display screen with a pixel pitch of 0.14 mm, the louver pitch is 0.175 mm or more (0.14 mm×1. 25 or more). Here, it is assumed that the width of the light blocking band 3 is 0.015 mm. If the louver pitch is set to 0.175 mm and the viewing angle θ is set to 40°, the thickness of the louver layer is 0.64 mm. is 0.28 mm. If the louver pitch is set to 0.210 mm and the viewing angle θ is set to 40°, the thickness of the louver layer is 0.78 mm. is 0.34 mm.

The light transmittance of the louver layer 1 can be adjusted by the ratio of the width of the light transmission zone 2/the width of the light shielding zone 3. FIG. The ratio represented by the width of the light shielding band 3/the width of the light transmitting band 2 is preferably 0.005 to 1, more preferably 0.06 to 0.35.

The louver pitch of the viewing angle control sheet 10 is 0.060 mm to 0.060 mm from the viewpoints of suppressing the visibility of interference fringes, lowering the bias angle, ensuring a viewing angle θ of 40 to 90°, good light transmittance, and the like. 250 mm is preferred, 0.080 mm to 0.220 mm is more preferred, and 0.100 mm to 0.200 mm is even more preferred.
In addition, by attaching the viewing angle control sheet 10, it is possible to suppress the visibility of interference fringes, reduce the bias angle, ensure a viewing angle θ of 40 to 90°, and easily realize a favorable light transmittance. The pixel pitch of the screen is preferably 0.040 mm to 0.160 mm, more preferably 0.050 mm to 0.150 mm, even more preferably 0.060 mm to 0.140 mm.

(Material for light transmission band)
It is preferable that the material of the light transmission band 2 constituting the louver layer 1 is a highly transparent resin. Specifically, the light transmittance (light transmittance) of only the light transmission band 2 of the louver layer 1 when light is transmitted in the thickness direction of the louver layer 1 is 75% or more, preferably 85%. A resin having high transparency as described above is preferable. Here, the upper limit of the light transmittance is not particularly limited, and can be, for example, 99.99% or less. As the resin, for example, a highly transparent thermoplastic resin or thermosetting resin is used, and specific examples include cellulose resins, polyolefin resins, polyester resins, silicone resins, polystyrene resins, and polyvinyl chloride resins. , acrylic resins, polycarbonate resins, and the like. Of these, silicone resins are preferred, and silicone rubbers are particularly preferred in terms of heat resistance, chemical resistance, decomposition resistance, transparency and flexibility. The silicone rubber may be a composition containing components other than the silicone resin.

Silicone rubbers include, for example, silicone rubber compositions generally called millable rubbers, which are composed of diorganopolysiloxane whose molecular chain ends are blocked with hydroxysilyl groups or vinylsilyl groups and organic peroxides; A so-called addition reaction in which an organohydrogenpolysiloxane having at least three silicon-bonded hydrogen atoms (=SiH bonds) in the molecule and a platinum-based catalyst are blended with a diorganopolysiloxane having at least two vinyl groups. type of organosilicone rubber composition, and the like.

(Material of shading band)
The material of the light shielding band 3 constituting the louver layer 1 is not particularly limited. Colored resins are preferred. The resin material forming the light transmission band 2 and the resin material as the base material of the light shielding band 3 may be the same or different, but the adhesion between the light transmission band 2 and the light shielding band 3 It is preferable that the two resin materials are the same from the viewpoint of easily obtaining a good quality.

The color tone of the light-shielding band 3 may be black, red, yellow, green, blue, light blue, etc., as long as sufficient light-shielding properties are obtained. The color tone and light-shielding properties of the light-shielding band 3 can be adjusted by the type and amount of coloring agent added. Specifically, the light-shielding property is such that only the light-shielding band 3 of the louver layer 1 has a light transmittance of 20% or less, preferably 5% or less when light is irradiated in the thickness direction of the louver layer 1. It is preferred to have The light transmittance may be 0%. Moreover, since the color tone of the light-shielding band is a color tone that can be recognized when looking at the louver layer 1, it is preferable to design the louver layer 1 in consideration of decorativeness.

Specific examples of colorants include general organic pigments such as carbon black, iron oxide, titanium oxide, yellow iron oxide, disazo yellow, and phthalocyanine blue, or inorganic pigments. One kind of coloring agent may be used, or two or more kinds thereof may be used. Moreover, when a black pigment is not used, it is preferable to use a white pigment together in order to obtain good light-shielding properties.

At least one of the light transmission band 2 and the light shielding band 3 is preferably made of silicone rubber. Since silicone rubber is excellent in heat resistance, chemical resistance, decomposition resistance, transparency, flexibility, etc., it is extremely excellent as an optical member.
From the viewpoint of enhancing the adhesiveness of the light-shielding band 3 to the light-transmitting band 2, the light-shielding band 3 is preferably made of silicone rubber, like the light-transmitting band 2.

[Protective layer 4]
The protective layer 4 is a resin layer. The surface of the protective layer 4 may be subjected to known surface treatments in the field of resin moldings, such as antireflection treatment (AR treatment), antiglare treatment (AG treatment), hard coat treatment, and the like.
Examples of resins that form the protective layer 4 include acrylic resins and polycarbonates.
The thickness of the protective layer 4 is, for example, 0.030 mm to 2.000 mm.
At least a portion of the protective layer 4 may be transparent, and the other portion may be opaque by printing or decoration.
The transparent portion of the protective layer 4 preferably has a light transmittance of 75 to 99.99%.

[Adhesion layer]
Viewing angle control sheet 10 has an adhesive layer (not shown) between louver layer 1 and protective layer 4 .
The adhesive layer of this embodiment is made of silicone rubber. The adhesive layer may be formed of a known adhesive other than silicone rubber, which adheres the resin layers together. However, since the louver layer 1 is made of silicone rubber, the adhesive layer should be made of silicone rubber from the viewpoint of adhesion with the louver layer 1 and reduction of interface reflection between the louver layer 1 and the adhesive layer. is preferred. Specific examples of the silicone rubber are the same as the specific examples of the silicone rubber of the louver layer 1 to be described later.
The thickness of the adhesive layer is thinner than that of the protective layer 4, and can be, for example, about 0.1 μm to 50 μm, preferably 5 μm to 30 μm.

[Base layer 5]
The base layer 5 is a resin layer. As a material for the resin layer, for example, a highly transparent thermoplastic resin or thermosetting resin is used. Specific examples include cellulose resins, polyolefin resins, polyester resins, silicone resins, polystyrene resins, polyvinyl chloride resins, acrylic resins, polycarbonate resins, and the like. Among these, polycarbonate is preferable from the viewpoint of enhancing heat resistance, rigidity and toughness.
The thickness of the base layer 5 is, for example, 0.030 mm to 2.000 mm.
At least part of the base layer 5 may be transparent, and the other part may be opaque by printing or decoration.
Preferably, the transparent portion of the base layer 5 has a light transmittance of 75 to 99.99%.
Protective layers 4 may be provided on both sides of the louver layer 1 , and in this case, one of the protective layers 4 corresponds to the base layer 5 .

On the outer surface 5a of the base layer 5, a transparent member such as an optional transparent layer or transparent film may be provided, and examples thereof include known adhesive layers, adhesive layers, transparent films, protective sheets, and the like.

Examples of materials for the adhesive layer include elastomer-based adhesives, acrylic-based adhesives, urethane-based adhesives, and rubber-based adhesives. Examples of the elastomeric pressure-sensitive adhesive include pressure-sensitive adhesives containing silicone rubber, silicone gel, urethane rubber, urethane gel, and the like. When using an elastomer-based pressure-sensitive adhesive, it is preferable to subject the surface of the pressure-sensitive adhesive layer to a known mirror finish in order to increase its transparency.

The resin constituting the viewing angle control sheet 10 may optionally contain known additives in the field of resin films, such as ultraviolet absorbers, infrared absorbers, and colorants, for the purpose of improving weather resistance, improving design properties, and the like. may be contained.

[Manufacturing method of viewing angle control sheet]
The louver layer 1 constituting the viewing angle control sheet 10 can be manufactured, for example, by the following method. First, a plurality of first sheets of a desired thickness made of the constituent material of the light-transmitting band 2 and a plurality of second sheets of a desired thickness made of the constituent material of the light-shielding band 3 are alternately laminated. Then, heat and pressure are applied to form a block body in which the plurality of sheets are integrated.

Then, the louver layer 1 is obtained by slicing the block along a cutting plane perpendicular to the sheet surface. The thickness (slice width) at the time of slicing corresponds to the thickness of the louver layer 1 . The angle between the surface of the louver layer 1 and the light shielding band 3 can be adjusted by slicing the block on a plane inclined with respect to the sheet surface.

The method for laminating and integrating the louver layer 1, the protective layer 4, and the base layer 5 is not particularly limited, and a known technique for laminating resin layers can be used.
As an example, there is a method of applying a silicone rubber adhesive to the first surface of the louver layer 1 and adhering the protective layer 4 prepared in advance. A base layer 5 can be formed on the second surface of the louver layer 1 by a similar method.

The viewing angle control sheet 10 is obtained by laminating the louver layer 1, the protective layer 4, and the base layer 5, and molding the integrated laminate into a desired shape. The planar shape of the viewing angle control sheet 10 is not particularly limited, and any shape such as a rectangle, polygon, circle, or ellipse may be appropriately adopted according to the shape of the display screen to be installed.

<Other embodiments>
The viewing angle control sheet 10 exemplified above has the protective layer 4 and the base layer 5, but the protective layer 4 and the base layer 5 in the viewing angle control sheet of the present invention are arbitrary layers, and either one or both You don't have to.
The angle formed by the surface of the louver layer 1 and the light shielding band 3 in the viewing angle control sheet 10 is 90 degrees, and the light shielding band 3 penetrates the louver layer 1 in parallel with the thickness direction (Z direction). , the angle formed by the viewing angle control sheet of the present invention is not limited to 90 degrees, but can be set arbitrarily within the range of, for example, 45 degrees to 90 degrees. FIG. 4 illustrates a cross-sectional view of the viewing angle control sheet 15 having an angle of 70 degrees.

<Multilayer Viewing Angle Control Sheet>
In the above description, the viewing angle control sheet according to the present invention has a single louver layer. The viewing angle control sheet according to the present invention may have two louver layers. Hereinafter, the configuration of the viewing angle control sheet 20 in which two louver layers are laminated will be described with reference to FIG.

FIG. 5 is a perspective view schematically showing an enlarged part of the viewing angle control sheet 20. As shown in FIG. In FIG. 5, the thickness direction of the viewing angle control sheet 20 is the Z direction, the light source side (display screen side) of the light entering the sheet 20 is the Z1 side, and the light passing through the sheet 20 is emitted. The irradiation side (viewing side) is the Z2 side. Also, the two directions perpendicular to each other in the plane perpendicular to the Z direction are defined as the X direction and the Y direction, respectively.

In the viewing angle control sheet 20, a first transparent resin layer 21, a first louver layer 22, a second transparent resin layer 23, a second louver layer 24, and a protective layer 25 are laminated in order from the Z1 side in the thickness direction. and integrated with each other.
The first transparent resin layer 21 is provided on the Z1 side surface (first surface) of the first louver layer 22, and the protective layer 25 is provided on the Z2 side surface (second surface) of the second louver layer 24. The second transparent resin layer 23 is provided on the Z2 side surface (second surface) of the first louver layer 22 , that is, on the Z1 side surface (first surface) of the second louver layer 24 .
The overall planar shape of the viewing angle control sheet in the XY plane (the plane perpendicular to the Z direction) is, for example, rectangular, but can be changed as appropriate according to the shape of the place where it is installed.

The protective layer 25 of the viewing angle control sheet 20 has the same configuration as the protective layer 4 of the viewing angle control sheet 10 . The second transparent resin layer 23 of the viewing angle control sheet 20 has the same configuration as the adhesive layer of the viewing angle control sheet 10 or the protective layer 4 or base layer 5 of the viewing angle control sheet 10 . The first transparent resin layer 21 of the viewing angle control sheet 20 has the same configuration as the base layer 5 of the viewing angle control sheet 10 .

The first louver layer 22 has light transmission bands 26 and light shielding bands 27 alternately repeated in the Y direction. Both the light transmission band 26 and the light shielding band 27 are band-shaped extending in the X direction, and the width in the Y direction is uniform and constant. The plurality of light transmission bands 26 have the same width, and the plurality of light shielding bands 27 have the same width.

The second louver layer 24 has light transmission bands 28 and light shielding bands 29 alternately repeated in the X direction. Both the light transmission band 28 and the light shielding band 29 are band-shaped extending in the Y direction, and the width in the X direction is uniform and constant. 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 viewing angle control sheet 20 shown in FIG. 5, the light shielding bands of the two laminated louver layers 22 and 24 are arranged such that the crossing angles of the light shielding bands are approximately 90° in plan view. Here, the intersection angle may be an angle other than 90°, or an arbitrary angle selected from 0 to 90°. The thicknesses of the first louver layer 22 and the second louver layer 24 and the thicknesses of the light transmission zone and the light shielding zone in each louver layer are set independently and may be the same or different.

The louver pitch of at least one of the two louver layers (the first louver layer 22 and the second louver layer 24) of the viewing angle control sheet 20 is a predetermined pitch with respect to the pixel pitch described above. Just do it. That is, one louver layer may correspond to the viewing angle control sheet of the present invention, and the other louver layer may or may not correspond to the viewing angle control sheet of the present invention.

The viewing angle control sheet 20 shown in FIG. 5 has a configuration in which two of the viewing angle control sheets 10 shown in FIG. is. Each of the transparent resin layers 21 and 23 has the same structure as the base layer 5 of the viewing angle control sheet 10 .
In the viewing angle control sheet 20, the first louver layer 22 controls the viewing angle along the Y direction, and the second louver layer 24 controls the viewing angle along the X direction. Viewing angles in two directions can be controlled simultaneously.

The manufacturing method of the viewing angle control sheet 20 is not particularly limited as long as the louver layers 22 and 24, the transparent resin layers 21 and 23 and the protective layer 25 are laminated and integrated. For example, the first transparent resin layer 21 is formed by applying a material for forming the first transparent resin layer 21 to the first surface of the first louver layer 22 and curing the material. After that, a curable material for forming the second transparent resin layer 23 is applied to the second surface of the first louver layer 22, and the second louver layer 24 is placed on the coating film before it is completely cured. to cure. Thereby, the second transparent resin layer 23 is formed, and the first louver layer 22 and the second louver layer 24 can be adhered via the second transparent resin layer 23 . Subsequently, the protective layer 25 is formed on the second surface of the second louver layer 24 to obtain the viewing angle control sheet 20 . However, instead of using the second transparent resin layer 23, the first louver layer 22 and the second louver layer 24 may be bonded with an adhesive layer. In this case, the thickness of the second transparent resin layer 23 can be reduced.

≪How to use the viewing angle control sheet≫
The viewing angle (visible angle) can be controlled by installing the viewing angle control sheet so as to cover at least part of the display screen of the information display device. Thereby, for example, peeping from the side can be prevented.
The viewing angle control sheet of the second aspect of the present invention is used by attaching the viewing angle control sheet of the first aspect to at least a part of the display screen of a display device having a pixel pitch of 0.15 mm or less, and It's a way to control the corners.
Since the pixel pitch of the attached display screen is much smaller than the louver pitch, it is possible to suppress the interference fringes from being visually recognized. As a specific pixel pitch, for example, 0.040 mm to 0.160 mm is preferable, 0.050 mm to 0.150 mm is more preferable, and 0.060 mm to 0.140 mm is even more preferable. Within the above range, the viewing angle can be sufficiently controlled by attaching the viewing angle control sheet of the first aspect.
As a specific mounting method, for example, there is an installation method in which the outer surface 5a of the base layer 5 of the rectangular viewing angle control sheet 10 is brought into close contact with the transparent substrate constituting the display screen.
It is also preferable to install the viewing angle control sheet so as to cover the display screen of the instrument panel in the vehicle. It is possible to prevent the light of the display screen from reflecting on the windshield.

The pixel pitch of the display device on which the viewing angle control sheet is installed is the cycle in which the pixels arranged on the display screen or inside thereof are repeated. As described above, when the display screen is viewed in plan, the arrangement of pixels can be regarded as a two-dimensional lattice of an xy orthogonal coordinate system, so the display screen has two pixel pitches that are orthogonal to each other.
The direction of the pixel pitch is the direction of the period in which the pixels are repeated. In the xy orthogonal coordinate system, if the direction of the first pixel pitch is the x-axis direction, the direction of the second pixel pitch is the y-axis direction. The directions of the two pixel pitches in a general display device often coincide with the horizontal direction and the vertical direction of the display screen, respectively.
When installing the viewing angle control sheet, the pixel pitch to be compared with the louver pitch should be in the direction of the pitch (repetition period) in the direction where the angle (bias angle) with respect to the direction of the louver pitch is less than 45°. There is The directions of the louver pitch and the pixel pitch illustrated in FIG. 3 have been described above, so the description is omitted here.

If the orientation of the pixel pitch to be compared with the louver pitch of the viewing angle control sheet is the horizontal direction of the display screen, the orientation of the louver pitch should basically be the horizontal direction of the display screen. Consider adding. Also, if the orientation of the pixel pitch to be compared with the louver pitch of the viewing angle control sheet is in the vertical direction of the display screen, the orientation of the louver pitch should basically be in the vertical direction of the display screen. Consider adding corners.
When the angle (bias angle) between the direction of the pixel pitch and the direction of the louver pitch is set to 0 to 20°, the visual recognition of the interference fringes is suppressed, and the direction of control of the viewing angle θ is generally aligned with the direction of the pixel pitch. can be done. From the viewpoint of obtaining both of these effects more reliably, it is preferable to set the bias angle to 5 to 18 degrees.

The direction of the louver pitch of the viewing angle control sheet is preferably set according to the display screen to be installed. For example, in applications to prevent third parties from peeking at the display screen from the left and right, and applications to prevent reflections on the door glass from the display screen attached to the instrument panel of a car, the direction of the louver pitch does not affect the display. The horizontal direction of the screen is preferred. On the other hand, for the purpose of preventing reflection on the windshield from the display screen attached to the instrument panel of a vehicle, the orientation of the louver pitch is preferably the vertical direction of the display screen.
In addition, in applications where reflection from the display screen in the vertical and horizontal directions is prevented so that it can be viewed only from the front of the display screen, it is preferable to use the viewing angle control sheet 20 in which two louver layers are laminated. .

≪Display device≫
The display device of the third aspect of the present invention comprises a display screen having a pixel pitch of 0.15 mm or less,
and the viewing angle control sheet of the first aspect attached to the display screen.
A display device main body having a display screen may include a display screen having a pixel pitch of 0.15 mm or less, and examples thereof include known information terminals such as high-definition notebook PCs and smartphones. The direction of the pixel pitch is preferably parallel to the horizontal or vertical direction of the display screen. The angle (bias angle) between the pixel pitch direction of the display screen and the louver pitch direction of the viewing angle control sheet attached to the display screen is preferably 0 to 20°, more preferably 5 to 18°. .

<<Method for manufacturing display device>>
A method for manufacturing a display device according to the fourth aspect of the present invention is a method for manufacturing a display device according to the third aspect. The method of attaching the viewing angle control sheet to the display screen is not particularly limited, and for example, the method of attaching it to the display screen as described in the second aspect can be mentioned. When mounting, the angle (bias angle) between the direction of the louver pitch of the viewing angle control sheet and the direction of the pixel pitch of the display screen is preferably 0 to 20°, more preferably 5 to 18°. .

The following examples are illustrative of the invention.
[Production Example 1]
A viewing angle control sheet 10 shown in FIGS. 1 and 2 was manufactured.
First, as a material for the light transmission band 2, a first sheet having a thickness of 100 μm made of transparent silicone rubber (trade name: KE-153-U, manufactured by Shin-Etsu Chemical Co., Ltd.) was prepared.
Separately, as a material for the light shielding band 3, a thickness made of a material obtained by adding 15 parts by mass of carbon black to 100 parts by mass of transparent silicone rubber (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KE-153-U) A second sheet with a thickness of 10 μm was prepared.
A plurality of first sheets and a plurality of second sheets were alternately laminated and heated, vulcanized and pressurized to form a block formed by integrating the plurality of sheets.
A louver layer 1 was produced by slicing the block into a thickness of 260 μm along a cut surface perpendicular to the sheet surface.

Then, a 200 μm thick polycarbonate film was prepared as the protective layer 4 . Liquid silicone rubber (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KE-1987) was applied to the surface of this film to a thickness of about 20 μm using a screen printer. It was placed on the first surface and heat-vulcanized and bonded.
By the same method, a base layer 5 made of a polycarbonate film having a thickness of 200 μm was formed on the second surface of the louver layer 1 to obtain a viewing angle control sheet 10 .

The viewing angle control sheet 10 produced in this production example has a louver pitch of 0.110 mm (110 μm) and a viewing angle of about 60°. The viewing angle control sheet 10 was cut to adjust the outer shape so that the vertical and horizontal size in plan view was 12 cm×7 cm and the direction of the louver pitch was in the horizontal direction.

[Production Example 2]
A viewing angle control sheet 10' was produced in the same manner as in Production Example 1, except that the thickness of the first sheet was changed to 120 μm.
The viewing angle control sheet 10' produced in this production example has a louver pitch of 0.120 mm (120 μm) and a viewing angle of about 72°. The viewing angle control sheet 10 was cut to adjust the outer shape so that the vertical and horizontal size in plan view was 12 cm×7 cm and the direction of the louver pitch was in the horizontal direction.

<Evaluation>
[Test Example 1]
When the viewing angle control sheet 10 (louver pitch: 0.110 mm) produced in Production Example 1 was brought into close contact with the display screen of a smartphone (pixel pitch: 0.060 mm), a clear image was obtained at a bias angle of 10 to 20°. No interference fringes were observed.
In this test example, the louver pitch is 1.83 times the pixel pitch. It was confirmed that when the louver pitch is sufficiently wider than the pixel pitch, the interference fringes are less visible.

[Test Example 2]
When the viewing angle control sheet 10′ (louver pitch: 0.130 mm) produced in Production Example 2 was brought into close contact with the display screen (pixel pitch: 0.14 mm) of a high-definition notebook PC, the bias angle was 10 to 20°. Clear interference fringes were visible.
In this test example, the louver pitch is 0.93 times the pixel pitch. It was confirmed that when the louver pitch and the pixel pitch are close, the interference fringes are easily visible.

DESCRIPTION OF SYMBOLS 1... Louver layer 2... Light transmission zone 3... Light shielding zone 4... Protective layer 4a... Surface of protective layer 5... Base layer 5a... Outer surface of base layer 10... Viewing angle control sheet 20... Viewing angle control Sheet 21... First transparent resin layer 22... First louver layer 23... Second transparent resin layer 24... Second louver layer 2
5 Protective layer 26 Light transmission zone 27 Light shielding zone 28 Light transmission zone 29 Light shielding zone

Claims (8)

A viewing angle control sheet attached to a display screen of a display device having a pixel pitch of 0.15 mm or less,
A louver layer in which light transmission bands and light blocking bands are alternately arranged , a protective layer optionally provided on the first surface of the louver layer via an arbitrary adhesive layer, and the louver layer Only a base layer that may optionally be provided via an optional adhesive layer on the second surface of
The pitch of the light-shielding band is 1.25 times or more the pixel pitch and is 0.060 mm to 0.250 mm,
The viewing angle control sheet , wherein the louver layer has a thickness of 0.100 mm to 5.000 mm . 2. The viewing angle control sheet according to claim 1, wherein an angle formed by the direction of the pitch of the light-shielding bands and the direction of the pixel pitch is 20[deg.] or less in plan view with respect to the louver layer . A louver layer in which light transmission bands and light shielding bands are alternately arranged on a display screen of a display device having a pixel pitch of 0.15 mm or less; and a viewing angle control sheet comprising only a base layer that may optionally be provided on the second surface of the louver layer via an optional adhesive layer is attached to the display screen. A viewing angle control method for controlling a viewing angle,
The pitch of the light-shielding band is 1.25 times or more the pixel pitch and is 0.060 mm to 0.250 mm,
The viewing angle control method , wherein the louver layer has a thickness of 0.100 mm to 5.000 mm . 4. The viewing angle control method according to claim 3, wherein an angle formed by the direction of the pitch of the light-shielding bands and the direction of the pixel pitch is 20[deg.] or less in plan view with respect to the display screen. A display device comprising: a display device body including a display screen having a pixel pitch of 0.15 mm or less; and a viewing angle control sheet attached to the display screen,
The viewing angle control sheet comprises a louver layer in which light transmission bands and light blocking bands are alternately arranged , a protective layer optionally provided on the first surface of the louver layer via an arbitrary adhesive layer, and only a base layer that may optionally be provided on the second surface of the louver layer via an optional adhesive layer ,
The pitch of the light-shielding band is 1.25 times or more the pixel pitch and is 0.060 mm to 0.250 mm,
The display device , wherein the louver layer has a thickness of 0.100 mm to 5.000 mm . 6. The display device according to claim 5, wherein an angle formed by the direction of the pitch of the light-shielding bands and the direction of the pixel pitch is 20[deg.] or less in plan view with respect to the display screen. A method of manufacturing a display device comprising a step of attaching a viewing angle control sheet to a display screen, wherein the display screen has a pixel pitch of 0.15 mm or less,
The viewing angle control sheet comprises a louver layer in which light transmission bands and light shielding bands are alternately arranged , a protective layer optionally provided on the first surface of the louver layer via an arbitrary adhesive layer, and , comprising only a base layer that may optionally be provided on the second surface of the louver layer via an optional adhesive layer ,
The pitch of the light-shielding band is 1.25 times or more the pixel pitch and is 0.060 mm to 0.250 mm,
The method for manufacturing a display device , wherein the louver layer has a thickness of 0.100 mm to 5.000 mm . 8. The method of manufacturing a display device according to claim 7, wherein an angle formed by the direction of the pitch of the light-shielding bands and the direction of the pixel pitch in plan view with respect to the display screen is 20[deg.] or less.

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