JP2015200795A - Daylighting film and day lighting tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a daylighting film that prevents peeping without reducing daylighting efficiency.SOLUTION: A daylighting film 1 comprises a base portion 3 having a plurality of grooves formed to be spaced apart from each other along one surface thereof and a plurality of louver portions 4 obtained by filling the plurality of grooves with a filling material having a refractive index different from that of the base portion. For at least some of the plurality of louver portions, a shortest distance (a) from a prescribed point in an end section on a side opposite the one surface to the one surface, and a shortest distance (b) along the one surface from a point of intersection between a vertical line drawn from the prescribed point and the one surface to an adjacent louver portion are set such that a value obtained by dividing (b) by (a) is no greater than a predetermined value.

Description

  The present invention relates to a daylighting film and a daylighting tool.

  Light control sheet that improves daylighting efficiency by deflecting outside light incident on the window toward the indoor ceiling as part of efforts to reduce carbon dioxide emissions and reduce power consumption by reducing the intensity of indoor lighting Has been proposed. For example, in Patent Document 1, a light control sheet having a structure in which transmissive portions and light-shielding portions are alternately arranged is attached to, for example, a window glass, and sunlight is taken in indoors in summer due to a difference in the incident angle of sunlight. Have been disclosed, and the technology for increasing the uptake of sunlight in winter is disclosed.

JP 2010-259406 A

  The light control sheet of Patent Document 1 described above and other conventional daylighting films for the purpose of daylighting include a base portion having a plurality of grooves, and a plurality of louver portions filled in these grooves, By utilizing the difference in refractive index between the base portion and the louver portion, external light incident on the daylighting film is guided toward the indoor ceiling or wall. This type of daylighting film may be used as a daylighting window by being attached to a window glass or sandwiched between glass sheets to form a laminated glass.

  Also, in general houses with two or more floors, a veranda or balcony is provided outside the window across the window, and the veranda or balcony has a vertical lattice shape for the purpose of preventing falling and taking in sunlight and wind. Handrails are often provided.

  However, with a vertical grid-like handrail, the line of sight passes through the gaps of the vertical grid when looked into from a veranda or balcony obliquely, and peeping cannot be prevented. For this reason, it is conceivable to provide a handrail in the form of a horizontal grid, but the horizontal grid generally uses an opaque material, which blocks sunlight and takes it indoors from the window through a veranda or balcony. The amount of sunlight stored is reduced compared to the vertical grid.

  It is also conceivable to prevent the peeping by making the handrails semi-transparent, that is, a mat-like base material having a high light diffusibility (haze value), instead of using a lattice shape. However, in such a base material, generally, the higher the haze value, the greater the amount of backward diffusion, so the light transmittance decreases, and in order to achieve peep prevention, the lighting performance (lighting efficiency) is sacrificed. It was.

  In addition, when a daylighting film such as that disclosed in Patent Document 1 is applied to the window of a house that is located higher than the line of sight, it is not designed to prevent peeping. The performance was insufficient.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a daylighting film and a daylighting tool capable of preventing peeping without reducing the daylighting efficiency.

In order to solve the above-described problem, in one aspect of the present invention, a base portion having a plurality of grooves formed separately along one surface;
A daylighting film comprising a plurality of louver portions having a refractive index different from that of the base portion and disposed in the plurality of grooves,
The daylighting film is installed in the vertical direction of the installation surface,
When the line of sight is directed to the daylighting film obliquely upward at an elevation angle θ from a predetermined height at a position a predetermined distance away from the daylighting film along the installation surface, at least some louvers of the plurality of louver portions A is the shortest distance from a predetermined position on the opposite end of the one surface to the one surface, and from the intersection of the perpendicular to the one surface from the predetermined position and the one surface Provided is a daylighting film that sets a and b so that a value obtained by dividing b by a is less than or equal to tan θ, where b is the shortest distance to an adjacent louver portion along one surface. Is done.

  The refractive index of the louver part may be lower than the refractive index of the base part.

  The elevation angle θ may be 3 degrees or more.

The daylighting film may be installed in the vertical direction of the ground,
The cross-sectional shape of the louver portion may be a right triangle having right sides arranged on the ground side.

The length a may be in the range of 20 μm to 500 μm,
The b may have a length in the range of 50 μm to 500 μm.

  The lighting tool provided with the transparent base material arrange | positioned through the contact bonding layer in the said one surface side in the lighting film in any one of Claims 1 thru | or 6 may be provided.

  According to the present invention, peeping can be prevented without lowering the daylighting efficiency.

The figure which shows the cross-section of the lighting film 1 by one Embodiment. The figure explaining the shape and pitch of the louver part. The figure explaining the shape and pitch of the louver part 4 in case a cross-sectional shape is trapezoid shape. The figure which shows an example of the cross-sectional structure of the laminated glass.

  Hereinafter, embodiments of the present invention will be described in detail. In the drawings attached to the present specification, for convenience of illustration and understanding, the scale, the vertical / horizontal dimensional ratio, and the like are appropriately changed or exaggerated from those of the actual ones.

  FIG. 1 is a diagram showing a cross-sectional structure of a daylighting film 1 according to an embodiment. The daylighting film 11 of FIG. 1 is used by being laminated on, for example, a window or a daylighting tool, or incorporated in a window or daylighting tool.

  As shown in FIG. 1, a daylighting film 1 according to an embodiment has a base portion 3 having a plurality of grooves 2 formed separately along one surface 1 a and a refractive index different from that of the base portion 3. And a plurality of louver portions 4 arranged in the plurality of grooves 2. The interior of the louver part 4 may be a cavity or may be filled with a filling material having a refractive index different from that of the base part 3.

  For example, the base portion 3 has a higher refractive index than the plurality of louver portions 4. Thereby, the light incident on the base portion 3 from the outside is reflected at the interface with the louver portion 4 and is bounced upward obliquely. In order to reflect the light traveling inside the base portion 3 at the interface with the louver portion 4, it is desirable that the difference in refractive index between the base portion 3 and the plurality of louver portions 4 is 0.1 or more. For example, the refractive index of the base part 3 is set to about 1.6, and the refractive index of the louver part 4 is set to about 1.4.

  The cross-sectional shape of the louver part 4 is, for example, a triangle or a trapezoid. Alternatively, other shapes may be used. In FIG. 1, the cross-sectional shape of the louver part 4 is made into a right triangle, and the example which arrange | positions the slope on the upper side, ie, the side into which sunlight injects, is shown. By arranging the slope on the upper side, it becomes easy to totally reflect sunlight, and the totally reflected sunlight can be efficiently splashed toward the indoor ceiling.

  The louver part 4 is spaced apart along the one surface 1 a of the base part 3, and the line of sight from the normal direction of the one surface 1 a passes through the gap of the louver part 4. That is, it is structurally difficult to prevent the line of sight from the normal direction of one surface 1a. However, the line of sight obliquely below the predetermined angle with respect to the installation surface of the daylighting film 1 is incident on the lower surface of the louver 4 and refracted as shown by the arrow line y1 in FIG. It is reflected by and proceeds indoors downward. As a result, it is impossible to look directly into the room, and peeping can be prevented.

  As described above, in the present embodiment, the shape and pitch of the louver portion 4 are determined so as to prevent a line of sight obliquely below the predetermined angle θ from the normal direction of the one surface 1a. The pitch is a distance between adjacent louver portions 4. Further, it is desirable that the predetermined angle θ is as small as possible. For example, when the predetermined angle θ is 3 °, the peeping can be prevented until the distance from the surface 1a is about 28 m. Assuming a general residential area and assuming a peep from the sidewalk across the road from the house, the distance is about 10m. In the case of the above design, the performance is sufficient as a peep prevention performance. It has become.

  FIG. 2 is a diagram for explaining the shape and pitch of the louver portion 4. In FIG. 2, the cross-sectional shape of the louver part 4 is a triangle, and the shortest distance from the top P of the louver part 4 to the one surface 1a on the end opposite to the one surface 1a of the louver part 4 is defined as a. When the shortest distance from the intersection of the perpendicular line dropped from the top P of the louver part 4 to the one surface 1a and the one surface 1a to the adjacent louver part 4 along the one surface 1a is b, A and b are set so that the formula (1) holds.

  b / a ≦ predetermined value (1)

  The predetermined value is a value depending on the line-of-sight angle, that is, the predetermined angle θ described above. The direction of the line segment connecting a and b is the line-of-sight direction, and the angle formed by this line-of-sight direction and the installation surface of the daylighting film 1 is the line-of-sight angle, that is, the predetermined angle θ. In other words, the line-of-sight direction means that the daylighting film 1 is installed in the vertical direction of the installation surface, and obliquely upward at an elevation angle (predetermined angle) θ from a predetermined height on the position away from the daylighting film 1 along the installation surface. This is the direction when the line of sight is directed toward the daylighting film 1. The relationship between the elevation angle θ and the predetermined value of equation (1) is expressed by the following equation (2).

  tan θ = predetermined value (2)

  Therefore, the following expression (3) is derived from the expressions (1) and (2).

  b / a ≦ tan θ (3)

  The angle θ indicates a line-of-sight angle when a human looks up the lighting film 1 obliquely upward, and is, for example, 3 degrees as described above. More specifically, the angle θ is a line-of-sight angle when the line of sight is directed above the reference height with respect to the height of a general human eye. tan θ when θ = 3 ° is about 0.0524. Therefore, the above-described equation (3) indicates that the ratio of b and a is, for example, about 0.0524 or less.

  The value of tan θ decreases as the angle θ decreases. Therefore, the value of a must be made larger than the value of b. That is, when the value of a is made larger than the value of b, peeping can be prevented even at a smaller angle θ.

  Thus, a predetermined position on the end of the louver part 4 opposite to the one surface 1a, that is, the shortest distance a from the top P of the louver part 4 to the one surface 1a, and the one surface from the top of the louver part 4 If the shortest distance b from the intersection of the perpendicular line 1a and the one surface 1a to the adjacent louver part 4 along the one surface 1a satisfies the above-described equation (3), the line of sight of the lighting film 1 It stops passing directly and can prevent peeping. In addition, since the values of a and b are determined by the shape and pitch of the louver part 4 in the daylighting film 1, for example, a is set to a value in the range of 50 μm to 500 μm, and b is in the range of 20 μm to 500 μm. Set to a value.

  When the expression (3) is satisfied, the line of sight directed obliquely upward hits the louver part 4 and does not pass through the daylighting film 1 directly. When the line-of-sight angle θ exceeds 3 degrees, tan θ is larger than when the line-of-sight angle θ = 3 °. Therefore, when the expression (3) is satisfied when the viewing angle θ = 3 °, the expression (3) is always satisfied when the viewing angle θ exceeds 3 degrees.

  When the line-of-sight angle θ is less than 3 degrees, the line-of-sight passes between the louver parts 4. However, the line-of-sight angle θ is less than 3 degrees because the human is daylighting from a position far away from the daylighting film 1. This is a case where the line of sight is directed toward the film 1.

  For example, when the line of sight is directed to the daylighting film 1 having a height of 3 m from the ground plane at a line-of-sight angle θ = 3 degrees, if the height of the human eye is 1.5 m from the ground plane, h in FIG. H = 3-1.5 = 1.5 m. Therefore, the shortest distance c between the person and the daylighting film 1 can be obtained by the following equation (4).

  c × tan θ = h (4)

  From equation (4), c = 1.5 m / tan (3 °) = about 28.6 m.

  Thus, in order to direct the line of sight at an angle θ = 3 degrees to a height of 3 m on the basis of the height of the human eye, the human must be at a position about 28.6 m away from the daylighting film 1. . If a person is further away from this position, θ <3 ° and the line of sight passes between the louver parts 4, but the line of sight is a daylighting film because the human eyesight is limited. Even if it passes directly through 1, it is impossible to visually recognize the indoor state at least with the naked eye. Therefore, it can be seen that if the angle θ is set to 3 ° and the shape and pitch of the louver portion 4 are determined so as to satisfy the above-described equation (3), peeping from a line of sight obliquely below can be reliably prevented.

  In FIG. 2, the cross-sectional shape of the louver part 4 is a triangle, and a and b described above based on the line of sight passing through the apex P of this triangle and the edge Q on the one surface 1a side of the adjacent louver part 4. However, the cross-sectional shape of the louver portion 4 is not limited to a triangle as described above. For example, when the cross-sectional shape of the louver part 4 is a trapezoidal shape as shown in FIG. 3, the edge part P adjacent to the adjacent louver part 4 is adjacent to the end part on the opposite side to the one surface 1 a of the louver part 4. It is desirable to set a and b described above based on the line of sight passing through the edge portion Q on the one surface 1a side of the louver portion 4. The reason for this is that the line-of-sight angle that passes through the two edges P and Q in FIG. 3 is the smallest of the line-of-sight angles that pass through the end of the louver 4 opposite to the one surface 1a. It is.

  Thus, the predetermined position on the end portion of the louver portion 4 when setting a can vary depending on the cross-sectional shape of the louver portion 4. Whatever the cross-sectional shape of the louver part 4 is, the predetermined position P on the end opposite to one surface 1a of one louver part 4 and the other of the two adjacent louver parts 4 and the other A and b are set so that the line of sight passing through the edge portion Q on the one surface 1a side of the louver portion 4 satisfies the above-described expression (3). Thereby, with respect to the daylighting film 1, most of the lines of sight incident obliquely upward can be blocked by the louver part 4, and peeping can be effectively prevented.

  The daylighting film 1 of FIG. 1 is disposed and sealed between laminated glasses, for example. FIG. 4 is a diagram illustrating an example of a cross-sectional structure of the laminated glass 10. As shown in the figure, adhesive layers 6 are disposed on both surfaces of the daylighting film 1, and a transparent substrate 7 such as glass is adhered from both surfaces via the adhesive layers 6.

  The daylighting film 1 according to the present embodiment is not only used for the laminated glass 10. For example, it may be bonded to only one side of the transparent substrate 7 such as glass via an adhesive layer. Moreover, the lighting film 1 by this embodiment may be adhere | attached on the surface of the slat of at least one part of a blind via an adhesive material. Alternatively, the daylighting film 1 may be incorporated inside each slat. Furthermore, the daylighting film 1 according to the present embodiment may be bonded to the surface of the roll-up blind via an adhesive.

  Next, the constituent material and manufacturing process of the daylighting film 1 according to the present embodiment will be described. As the material of the base portion 3, for example, a material obtained by mixing and homogenizing a photocurable prepolymer, a reactive dilution monomer, a mold release agent, and a photopolymerization initiator is used. When a base material (not shown) is bonded to the base portion 3, for example, a PET (polyethylene terephthalate) film is used as the base material. As the material of the base portion 3, a curable resin such as a thermosetting resin or an electron beam curable resin may be used instead of the ultraviolet curable resin.

  In order to form the groove 2 as shown in FIG. 1 in the base portion 3, for example, a mold roll is used. The surface of the mold roll is cut with a cutting tool in accordance with the shape of the groove 2 to form a plurality of convex portions corresponding to the shape of each groove 2. In order to satisfy the relationship of the above-mentioned formula (3), θ is set in advance, and at least one of a and b is varied to define the shape and pitch of the louver portion 4, and the surface of the mold loam is adjusted accordingly. Process it.

  The composition of the base portion 3 is filled between the mold roll and the nip roll formed with the convex portions and pressurized with both rolls. For example, the composition of the base portion 3 is cured by irradiating ultraviolet rays with a high-pressure mercury lamp. The base part 3 is formed. Thereafter, the base portion 3 is released from the mold roller by the peeling roller, and an intermediate member including the base portion 3 is produced.

  As a filling material filled in the groove 2 of the base portion 3, for example, an ultraviolet curable resin such as a photocurable prepolymer, a reactive dilution monomer, a light scattering material, and a photopolymerization initiator are mixed and uniform. Is used. A thermosetting resin or an electron beam curable resin may be used instead of the ultraviolet curable resin.

  As described above, in the present embodiment, the base portion 3 and the louver portion 4 have different refractive indexes. Both the base part 3 and the louver part 4 are made of a curable resin such as a thermosetting resin, an ultraviolet curable resin and an electron beam curable resin, but the type of curable resin and the additives contained therein. By changing these, the base portion 3 and the louver portion 4 can have a refractive index difference.

  The composition of the adhesive layer 6 is, for example, one or more of a thermoplastic resin such as polyvinyl acetal resin, ethylene vinyl acetate copolymer resin, ethylene acrylic copolymer resin, polyurethane resin and polyvinyl alcohol resin, It may be used by mixing with additives such as an antioxidant and an ultraviolet shielding agent, or may be formed by mixing an acrylic resin adhesive, a crosslinking agent, and a diluent. The composition of the adhesive layer 6 is made into a sheet or film and placed between the daylighting film 1 and the transparent substrate, and after applying pressure to extrude air, it is heated and integrated with the daylighting film 1. If it is liquid, it is applied to the release film and dried, and then attached to the daylighting film 1.

  As described above, in the present embodiment, the shortest distance from the predetermined position on one end of the louver 4 opposite to the one surface 1a to the one surface 1a is a, and the perpendicular is lowered from the predetermined position to the one surface 1a. A and b so that the value obtained by dividing b by a is less than or equal to a predetermined value, where b is the shortest distance from the intersection of one surface 1a to the adjacent louver portion 4 along one surface 1a. Therefore, the line of sight directed obliquely upward with respect to the daylighting film 1 is less likely to enter the indoors directly through the daylighting film 1, preventing peeping without reducing the daylighting efficiency, and ensuring privacy. I can plan.

  Therefore, if the daylighting film 1 according to the present embodiment is used, it is not necessary to attach a vertical lattice member for preventing peeping or a translucent flat plate to the outside of the window, the member cost can be reduced, the appearance is improved, and the daylighting efficiency is improved. Will also improve. By improving the daylighting efficiency, it is possible to reduce the frequency of use of illumination and weaken the intensity of illumination light, thereby reducing power consumption and greenhouse gas emissions.

  The aspect of the present invention is not limited to the individual embodiments described above, and includes various modifications that can be conceived by those skilled in the art, and the effects of the present invention are not limited to the contents described above. That is, various additions, modifications, and partial deletions can be made without departing from the concept and spirit of the present invention derived from the contents defined in the claims and equivalents thereof.

    1 daylighting film, 2 groove, 3 base part, 4 louver part, 6 adhesive layer, 10 laminated glass

Claims (6)

A base portion having a plurality of grooves formed apart along one surface;
A daylighting film comprising a plurality of louver portions having a refractive index different from that of the base portion and disposed in the plurality of grooves,
The daylighting film is installed in the vertical direction of the installation surface,
When the line of sight is directed to the daylighting film obliquely upward at an elevation angle θ from a predetermined height at a position a predetermined distance away from the daylighting film along the installation surface, at least some louvers of the plurality of louver portions A is the shortest distance from a predetermined position on the opposite end of the one surface to the one surface, and from the intersection of the perpendicular to the one surface from the predetermined position and the one surface The daylighting film in which the a and the b are set so that a value obtained by dividing the b by the a is not more than tan θ, where b is the shortest distance to the adjacent louver portion along one surface.   The daylighting film according to claim 1, wherein a refractive index of the louver portion is lower than a refractive index of the base portion.   The daylighting film according to claim 1, wherein the elevation angle θ is 3 ° or more. The daylighting film is installed in the vertical direction of the ground,
The daylighting film according to any one of claims 1 to 3, wherein a cross-sectional shape of the louver portion is a right-angled triangle having right-angle sides arranged on the ground side. A is a length in the range of 20 μm to 500 μm;
5. The daylighting film according to claim 1, wherein b is a length in a range of 50 μm to 500 μm.   A daylighting tool provided with the transparent base material arrange | positioned through the contact bonding layer in the said one surface side in the daylighting film in any one of Claims 1 thru | or 5.

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