Lighting film, laminate, and building structure

Abstract

To provide a lighting film that makes it difficult to peek into the inside of a building structure and enables light to be taken into the inside of the building structure.SOLUTION: A lighting film 10 is mounted in place so that a first plane 10a expands in the vertical direction. A transmissivity T1 of light entering the first plane 10a at an incident angle 40° with respect to the first plane 10a on a virtual plane perpendicular to and parallel in the vertical direction to the first plane 10a is smaller than a transmissivity T2 of light entering the first plane 10a from the upper side in the vertical direction at an incident angle 40° with respect to the first plane 10a. The lighting film 10 comprises an angle control layer 20 for controlling the angle at which light passes through and including a dichroic dye composition 21 and a liquid crystal composition 22. In an observation from a direction perpendicular to the virtual plane, the light absorption axis of the dichroic dye composition 21 is inclined with respect to the first plane 10a and extends so as to head progressively to the upper side in the vertical direction as it goes from a second plane 10b to the first plane 10a.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a light collecting film, a laminate, and a building.

Background Art

[0002] Techniques for making it difficult to peek into the interior of a building from the outside of the building through an opening such as a window are widely known (see, for example, Patent Document 1).

[0003] Patent Document 1 describes a technique for making it difficult to peek into the interior of a building from a window using a so-called magic mirror that appears like a mirror from the bright side and appears transparent when viewed from the dark side.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] It may be required to make it difficult to peek into the interior of a building from the outside of the building through an opening such as a window, and at the same time, to take in light from the outside of the building into the interior of the building through the opening. In particular, it may be required to make it difficult to peek into the interior of the building from below the opening through the opening, and at the same time, to take in light from above the opening into the interior of the building. Specifically, when an opening is provided on a floor of the building that is the second floor or higher, there is a possibility that the interior of the building can be peeked into from below the opening through the opening. Further, there may be a case where it is required to take in sunlight from above the opening into the interior of the building.

[0006] The present disclosure has been made in consideration of the above points, and an object thereof is to provide a light-transmitting film that makes it difficult to peek into the inside of a building and allows light to enter the inside of the building.

Means for Solving the Problems

[0007] Embodiments of the present disclosure relate to the following [1] to [8].

[0008] [1] A light-transmitting film having a first surface and a second surface located on the side opposite to the first surface, and being placed so that the first surface extends in the vertical direction, On a virtual plane perpendicular to the first surface and parallel to the vertical direction, the transmittance T1 of light incident on the first surface from below the vertical direction at an incident angle of 40° with respect to the first surface is smaller than the transmittance T2 of light incident on the first surface from above the vertical direction at an incident angle of 40° with respect to the first surface, Comprising a dichroic dye composition and a liquid crystal composition, and having an angle control layer for controlling the angle at which light passes through, In an observation from a direction perpendicular to the virtual plane, the light absorption axis of the dichroic dye composition is inclined with respect to the first surface and extends upward in the vertical direction as it goes from the second surface toward the first surface, A light-transmitting film in which the angle formed by the light absorption axis of the dichroic dye composition with respect to the direction perpendicular to the first surface is 20° or more and 40° or less.

[0009] [2] The value obtained by dividing the transmittance T2 by the transmittance T1 is 1.85 or more, and the light-transmitting film according to [1].

[0010] [3] The transmittance T1 is 6% or less, and the light-transmitting film according to [1] or [2].

[0011] [4] The transmittance T2 is 11% or more, and the light-transmitting film according to any one of [1] to [3].

[0012] [5] On the virtual plane, the maximizing light that travels in the direction that maximizes the transmittance when incident on the first surface enters the first surface from above the vertical direction, The incident angle of the maximizing light with respect to the first surface is 30° or more and 40° or less. The daylighting film according to any one of [1] to [4].

[0013] [6] The daylighting film according to any one of [1] to [5], further comprising an adhesive layer that constitutes the first surface of the daylighting film.

[0014] [7] The daylighting film according to any one of [1] to [6], and A light-transmitting member laminated on the daylighting film, comprising a laminate. A laminate fitted into an opening of a building.

[0015] [8] An opening, and The building according to [7], further comprising the laminate fitted into the opening.

Effect of the Invention

[0016] According to the embodiment of the present disclosure, while making it difficult to peek into the interior of the building, light can be introduced into the interior of the building.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11A

Figure 11B

Figure 12

Figure 13

BEST MODE FOR CARRYING OUT THE INVENTION

[0018] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. In the drawings attached to this specification, for the convenience of illustration and easy understanding, the scale, the aspect ratio of the vertical and horizontal dimensions, etc. are appropriately changed and exaggerated from those of the actual object.

[0019] In this specification, terms used to specify shapes, geometric conditions, and their degrees, such as terms like "parallel", "perpendicular", "identical", etc., and values of lengths and angles, etc., are not restricted to strict meanings, and will be interpreted to include ranges to the extent that similar functions can be expected.

[0020] Figs. 1 to 8 are diagrams showing an embodiment. Fig. 1 is a diagram showing an application example of the laminate 3 provided with the daylighting film 10 of the present embodiment. Fig. 2 is a diagram showing the laminate 3 provided with the daylighting film 10. The daylighting film 10 makes it difficult to peek into the inside of the building B as shown in Fig. 1, and enables light from the outside of the building to be taken into the inside of the building B.

[0021] In the example shown in Fig. 1, the building B includes an opening 2 and a laminate 3 fitted into the opening 2. The building B has floors above the second floor. In the example shown in Fig. 1, the building B is a two-story building. The opening 2 is provided in the wall 4 of the building B. The opening 2 is provided in a floor above the second floor of the building B. In the example shown in Fig. 1, the opening 2 is provided on the second floor of the building B. In the example shown in Fig. 1, the opening 2 is a window provided in the wall 4 of the building B. At least one side surface of the building B may be glass-covered. In this case, the glass-covered portion on the side surface of the building B can be regarded as the opening 2. Further, the glass used for the glass covering can be regarded as the light-transmitting member 5 of the laminate 3 described later. The entire surface of the building B may be glass-covered. The building B may be a building using large-area window glass. In this case, the portion where the large-area window glass is used can be regarded as the opening 2. Further, the large-area window glass can be regarded as the light-transmitting member 5 of the laminate 3 described later.

[0022] As shown in Figs. 1 and 2, the laminate 3 includes a daylighting film 10 and a light-transmitting member 5 laminated on the daylighting film 10. The laminate 3 is fitted into the opening 2 of the building B. In the example shown in Fig. 1, the laminate 3 is fitted into the opening 2 such that the daylighting film 10 is located on the inner side of the building than the light-transmitting member 5. The daylighting film 10 has a first surface 10a and a second surface 10b located on the side opposite to the first surface 10a. In the example shown in Fig. 1, the first surface 10a of the daylighting film 10 is directed toward the outside of the building.

[0023] The light-transmitting member 5 is not particularly limited as long as it is generally a member that is fitted into a window of a building to transmit light and contributes to daylighting inside the building. The material of the light-transmitting member 5 is, for example, glass or resin. In the example shown in FIG. 1, the light-transmitting member 5 is glass fitted into the opening 2 which is a window. In this case, by attaching the daylighting film 10 onto the surface of the light-transmitting member 5 which is this glass, a laminate 3 including the daylighting film 10 and the light-transmitting member 5 is formed.

[0024] In the example shown in FIG. 1, the wall 4 extends in the vertical direction. As a result, the daylighting film 10 included in the laminate 3 fitted into the opening 2 provided in the wall 4 is placed such that the first surface 10a extends in the vertical direction. When a plate-like member such as the wall 4 or a surface such as the first surface 10a "extends in the vertical direction", the angle formed by the plate-like member or the surface with respect to the vertical direction may be 30° or less, may be 20° or less, may be 10° or less, may be 5° or less, or may be 3° or less. In the example shown in FIG. 1, the wall 4 is parallel to the vertical direction. As a result, the daylighting film 10 is placed such that the first surface 10a is parallel to the vertical direction.

[0025] Next, the daylighting film 10 will be described. As described above, the daylighting film 10 is placed such that the first surface 10a extends in the vertical direction. FIG. 3 is a partial cross-sectional view showing a part of the cross-section obtained by cutting the daylighting film 10 of the present embodiment in a virtual plane perpendicular to the first surface 10a and parallel to the vertical direction. As shown in FIGS. 2 and 3, the daylighting film 10 includes an angle control layer 20. In the examples shown in FIGS. 2 and 3, the daylighting film 10 further includes an adhesive layer 30. In the examples shown in FIGS. 2 and 3, the adhesive layer 30 constitutes the first surface 10a of the daylighting film 10. The angle control layer 20 constitutes the second surface 10b of the daylighting film 10.

[0026] The angle control layer 20 controls the angle at which light passes through. As shown in FIG. 3, the angle control layer 20 includes a dichroic dye composition 21 and a liquid crystal composition 22.

[0027] In this embodiment, the liquid crystal composition 22 contains a polymerizable liquid crystal and a driving liquid crystal. In the light collecting film 10, the polymerizable liquid crystal is fixed by crosslinking. The driving liquid crystal is incorporated into the structure formed by the crosslinking of the polymerizable liquid crystal. As a result, the movement of the driving liquid crystal is restricted. The type of the polymerizable liquid crystal contained in the liquid crystal composition 22 is not particularly limited. As the polymerizable liquid crystal contained in the liquid crystal composition 22, a rod-like liquid crystal or a discotic liquid crystal can be used. From the viewpoint of easily controlling the dichroic dye composition 21 with the driving liquid crystal, the polymerizable liquid crystal is preferably a rod-like liquid crystal. As the driving liquid crystal contained in the liquid crystal composition 22, a positive liquid crystal used in a normal twisted nematic liquid crystal display can be used. The positive liquid crystal is a liquid crystal that, when a voltage is applied to a solution containing the liquid crystal, aligns in a direction parallel to the direction in which the voltage is applied.

[0028] The dichroic dye composition 21 is incorporated into the structure formed by the crosslinking of the polymerizable liquid crystal. As a result, the movement of the dichroic dye composition 21 is restricted. Therefore, the change in the direction of the light absorption axis L2 of the dichroic dye composition 21 shown in FIG. 3 is restricted. As an example, the direction of the light absorption axis L2 of the dichroic dye composition 21 is fixed by the polymerizable liquid crystal.

[0029] Consider a virtual plane perpendicular to the first surface 10a and parallel to the vertical direction. As described above, FIG. 3 corresponds to a cross-sectional view of the light collecting film 10 cut in the virtual plane. When observed from a direction perpendicular to the virtual plane, the light absorption axis L2 of the dichroic dye composition 21 is inclined with respect to the first surface 10a. The light absorption axis L2 of the dichroic dye composition 21 extends upward in the vertical direction as it goes from the second surface 10b toward the first surface 10a. The angle θ1 formed by the light absorption axis L2 of the dichroic dye composition 21 with respect to the direction perpendicular to the first surface 10a is 20° or more and 40° or less.

[0030] The materials and contents of the components included in the angle control layer 20 such as the dichroic dye composition 21 and the liquid crystal composition 22 are adjusted so that the light collecting film 10 has the characteristics regarding the light transmittance described later.

[0031] The film thickness t of the angle control layer 20 is adjusted so that the light collection film 10 has the characteristics regarding the light transmittance described later. The film thickness t of the angle control layer 20 is, for example, 5 μm or more and 20 μm or less. The film thickness t of the angle control layer 20 is, for example, 10 μm. Although not shown in FIG. 3, the angle control layer 20 may further include particles 45 described later in the description of the manufacturing method of the light collection film 10. In this case, the film thickness t of the angle control layer 20 can be adjusted by adjusting the size of the particles 45.

[0032] The adhesive layer 30 is a layer that adheres to other members by adhesive force. Due to the adhesive force of the adhesive layer 30, as shown in FIG. 2, the light collection film 10 can be adhered onto the surface of the light-transmitting member 5. The material of the adhesive layer 30 is not particularly limited as long as it does not prevent the light collection film 10 from exerting the effect of allowing light from the outside of the building B to enter the inside of the building B while making it difficult to peek into the inside of the building B. Although not shown, the light collection film 10 may not have the adhesive layer 30. In this case, the light collection film 10 may be fixed to the light-transmitting member 5 by means other than the adhesive layer 30.

[0033] The characteristics of the light collection film 10 regarding the light transmittance will be described. Consider a virtual plane perpendicular to the first surface 10a and parallel to the vertical direction. As described above, FIG. 3 corresponds to a cross-sectional view of cutting the light collection film 10 on the virtual plane. On the virtual plane, let the transmittance of the light L1 incident on the first surface 10a from the lower side in the vertical direction at an incident angle of 40° with respect to the first surface 10a be the transmittance T1. On the virtual plane, let the transmittance of the light L5 incident on the first surface 10a from the upper side in the vertical direction at an incident angle of 40° with respect to the first surface 10a be the transmittance T2. At this time, the transmittance T1 is smaller than the transmittance T2.

[0034] In this specification, the light transmittance refers to the total light transmittance. As the light transmittance, the transmittance of light traveling in the air and incident on the first surface 10a with the first surface 10a of the daylighting film 10 in contact with the air is measured. The light transmittance can be measured using a visual angle characteristic measurement and evaluation device (manufactured by ELDIM, product name "EZContrast") as the measurement device. More specifically, the light transmittance is measured by the following method. The sample to be measured is placed at the position where the sample of the measurement device is installed, which is a position on a surface light source such as a light table. Next, light is irradiated so as to pass through the sample from the light source and reach the detection unit of the measurement device, and the luminance of the light reaching the detection unit is measured. Further, with nothing installed at the position where the sample of the measurement device is installed, light is irradiated from the same light source, and the luminance of the light reaching the detection unit is measured. The transmittance is calculated as the ratio of the luminance when the sample to be measured is installed to the luminance when nothing is installed at the position where the sample of the measurement device is installed.

[0035] Since the transmittance T1 is smaller than the transmittance T2, the following effects can be obtained. It is possible to make it difficult to peek into the interior of the building B from below in the vertical direction with a line of sight forming an angle of about 40° with respect to the direction perpendicular to the first surface 10a. On the other hand, light traveling in the air in a direction forming an angle of about 40° with respect to the direction perpendicular to the first surface 10a and incident on the first surface 10a from above in the vertical direction can be taken into the interior of the building B through the daylighting film 10. In particular, sunlight is incident on the first surface 10a from above in the vertical direction. Since the transmittance T1 is smaller than the transmittance T2, sunlight traveling in the air in a direction forming an angle of about 40° with respect to the direction perpendicular to the first surface 10a and incident on the first surface 10a from above in the vertical direction can be taken into the interior of the building B through the daylighting film 10.

[0036] Regarding the effect that the transmittance T1 is smaller than the transmittance T2, a more detailed explanation will be given while giving examples of specific usage modes of the daylighting film 10. When looking into the interior of the building B through the opening 2 provided on the second floor of the building B, compared with the case of looking into the interior of the building B through the opening 2 provided on the third floor or higher of the building B, the distance from the ground to the opening 2 becomes smaller. Further, the angle formed by the line of sight from the ground with respect to the surface of the laminate 3 fitted in the opening 2 becomes larger. For this reason, when looking through the opening 2 provided on the second floor of the building B, it is easier to look into the interior of the building B through the opening 2 from below the opening 2 than when looking through the opening 2 provided on the third floor or higher of the building B. For this reason, the daylighting film 10 is required to particularly effectively make it difficult to look through from below the opening 2 when used for the laminate 3 fitted in the opening 2 provided on the second floor of the building B. In particular, when the opening 2 is provided on the second floor of the building B, when the opening 2 extends to the floor surface of the second floor, compared with the case where the opening 2 is provided at a position away from the floor surface of the second floor of the building B, by passing through the portion near the floor surface of the opening 2, it is easy to look into the interior of the building B from below the opening 2. For this reason, the daylighting film 10 is required to particularly effectively make it difficult to look through from below the opening 2 when the opening 2 extends to the floor surface of the second floor.

[0037] FIG. 4 is a diagram showing an example of a passerby A passing on the road outside the building B trying to peek into the inside of the building B through an opening 2 provided on the second floor of the building B and extending to the floor surface of the second floor. FIG. 5 is a diagram showing a different example of a passerby A passing on the road outside the building B trying to peek into the inside of the building B through the same opening 2 as in FIG. 4. The height w1 from the ground to the floor surface of the second floor of the building B shown in FIGS. 4 and 5 is about 3.5 m on average. The height w2 from the ground to the eyes of a human (passerby A) shown in FIGS. 4 and 5 is about 1.6 m on average. The width of the sidewalk C is about 3 m or more and 5 m or less on average. FIG. 4 shows the case where the width of the sidewalk C is 3 m. FIG. 5 shows the case where the width of the sidewalk C is 5 m. Usually, the passerby A passing through the sidewalk C is considered to pass near the center of the sidewalk C. In FIGS. 4 and 5, the height w1 is set to 3.5 m and the height w2 is set to 1.6 m. Further, in FIGS. 4 and 5, it is assumed that the passerby A is standing near the center of the sidewalk C. That is, it is assumed that the horizontal distance w3 between the passerby A and the building B in FIG. 4 is 1.5 m, and the horizontal distance w4 between the passerby A and the building B in FIG. 5 is 2.5 m. In this case, the angle formed by the line of sight L3 of the passerby A directed to the portion near the floor surface of the opening 2 in FIG. 4 with respect to the direction perpendicular to the first surface 10a is about 50°. The angle formed by the line of sight L4 of the passerby A directed to the portion near the floor surface of the opening 2 in FIG. 5 with respect to the direction perpendicular to the first surface 10a is about 35°.

[0038] On the other hand, since the transmittance T1 is smaller than the transmittance T2, it becomes difficult to peek into the interior of the building B from below in the vertical direction with a line of sight forming an angle of about 40° with respect to the direction perpendicular to the first surface 10a. It can be said that 40° is an angle close to the intermediate angle between approximately 35° and 50°. Thereby, even if the angle formed by the line of sight L4 directed by the passerby A toward the portion near the floor surface of the opening 2 with respect to the direction perpendicular to the first surface 10a is either about 35° or about 50°, it can be made difficult for the passerby A to peek into the interior of the building B. From the above, it can be made difficult for a passerby A passing through the general sidewalk C outside the building B to peek into the interior of the building B through the opening 2 provided on the second floor of the building B and extending to the floor surface of the second floor.

[0039] Regarding the effect of the transmittance T1 being smaller than the transmittance T2, it will be described in more detail while giving other examples of specific usage modes of the daylighting film 10. There may be a case where it is required to take in sunlight from above the opening 2 into the interior of the building B. In particular, from autumn to spring when the temperature and the daily solar radiation amount decrease, there may be a case where it is required to take in sunlight into the interior of the building B in the time zone near the time when the sun is at its zenith. In Japan, the solar altitude at noon on the Vernal Equinox and the Autumnal Equinox is about 55°. Furthermore, in Japan, the solar altitude at noon on the Winter Solstice is about 32°. Therefore, in particular, the average solar altitude at noon in the season when it is required to take in sunlight is about 40°.

[0040] On the other hand, since the transmittance T1 is smaller than the transmittance T2, sunlight traveling in the air in a direction forming an angle of about 40° with respect to the direction perpendicular to the first surface 10a and incident on the first surface 10a from above in the vertical direction can be taken into the interior of the building B through the daylighting film 10. Thereby, from the Autumnal Equinox to the Vernal Equinox sandwiching winter, sunlight can be taken into the interior of the building B in the time zone near the time when the sun is at its zenith.

[0041] From the perspective of making it difficult to peek into the interior of the building B from below the opening 2 while allowing light from above the opening 2 to enter the interior of the building B, the ratio of the transmittance T2 to the transmittance T1 is preferably large. The value obtained by dividing the transmittance T2 by the transmittance T1 is preferably 1.85 or more. The value obtained by dividing the transmittance T2 by the transmittance T1 is also denoted as T2 / T1. By having T2 / T1 be 1.85 or more, the effect of making it difficult to peek into the interior of the building B from below the opening 2 and the effect of allowing light from above the opening 2 to enter the interior of the building B can be more stably achieved simultaneously. T2 / T1 may be 2 or more.

[0042] In order to realize the daylighting film 10 in which the effect of making it difficult to peek into the interior of the building B from below the opening 2 and the effect of allowing light from above the opening 2 to enter the interior of the building B are achieved simultaneously, the inventors of the present case have intensively studied the daylighting film 10 with a large T2 / T1. As a result, it has been found that by setting the angle θ1 formed with respect to the direction perpendicular to the first surface 10a of the light absorption axis L2 of the dichroic dye composition 21 to be 20° or more and 40° or less, T2 / T1 can be made sufficiently large. In particular, it has been found that T2 / T1 can be made 1.85 or more. An example of the experiment in which the inventors of the present case have found that T2 / T1 can be made sufficiently large by setting the angle θ1 to be 20° or more and 40° or less will be described later in the examples.

[0043] As described above, the transmittance T1 is the transmittance of light incident on the first surface 10a from the lower side in the vertical direction at an incident angle of 40° with respect to the first surface 10a. The transmittance T2 is the transmittance of light incident on the first surface 10a from the upper side in the vertical direction at an incident angle of 40° with respect to the first surface 10a. The reason why T2 / T1 can be made particularly large with respect to the transmittance of light incident on the first surface 10a at an incident angle of 40° by setting the angle θ1 to be 20° or more and 40° or less, in other words, by keeping it within the range of ±10° centered around 30°, is considered to be as follows.

[0044] Light traveling in the air and incident on the light collection film 10 is considered to be refracted at the first surface 10a of the light collection film 10 or the like. As the refractive index of the components included in the light collection film 10, particularly the refractive index value of the angle control layer 20, a value of about 1.5 or more and 1.55 or less is assumed. In particular, when the angle control layer 20 includes the liquid crystal composition 22 containing a polymerizable liquid crystal, the refractive index value of the angle control layer 20 can be assumed to be about 1.5 or more and 1.55 or less.

[0045] Consider the case where the first surface 10a of the light collection film 10 is in contact with air. In this case, light traveling in the air in a direction making an angle of 40° with respect to the direction perpendicular to the first surface 10a is incident on the first surface 10a at an incident angle of 40°. This light is refracted at the first surface 10a so that the refraction angle is about 30°. Therefore, light incident on the first surface 10a from above in the vertical direction at an incident angle of 40° with respect to the first surface 10a is considered to be refracted so that the refraction angle is about 30°. By setting the angle θ1 within a range of ±10° centered on 30°, the light refracted so that the refraction angle is about 30° as described above is less likely to be absorbed by the dichroic dye composition 21 of the angle control layer 20. For this reason, by setting the angle θ1 to 20° or more and 40° or less, the transmittance T2, which is the transmittance of light incident on the first surface 10a from above in the vertical direction at an incident angle of 40° with respect to the first surface 10a, can be made particularly large. Furthermore, light incident on the first surface 10a from below in the vertical direction at an incident angle of 40° with respect to the first surface 10a can be absorbed by the dichroic dye composition 21 of the angle control layer 20. For this reason, the transmittance T1, which is the transmittance of light incident on the first surface 10a from below in the vertical direction at an incident angle of 40° with respect to the first surface 10a, can be made small. From the above, it is considered that the value of T2 / T1 can be made particularly large while making the transmittance T2 particularly large and making the transmittance T1 small.

[0046] Although the case where the first surface 10a of the daylighting film 10 is in contact with air has been described above, in the examples shown in FIGS. 1 and 2, the first surface 10a of the daylighting film 10 is in contact with the light-transmitting member 5. Also in this case, by setting the angle θ1 to be 20° or more and 40° or less, the light traveling in the air in a direction forming an angle of about 40° with respect to the direction perpendicular to the first surface 10a can be taken into the interior of the building B by entering the first surface 10a from the upper side in the vertical direction. An example of the action of the daylighting film 10 in this case will be described below. In the following, in particular, as an example of the action of the daylighting film 10, the action of the daylighting film 10 when the light traveling in the air enters the daylighting film 10 after passing through the light-transmitting member 5 will be described. However, when the light traveling in the air in a certain direction enters the angle control layer 20 of the daylighting film 10, the direction in which the light travels in the angle control layer 20 is the same whether the light enters the angle control layer 20 after passing through the light-transmitting member 5 from the air or directly enters the angle control layer 20 from the air, according to Snell's law. Further, when the light traveling in the air in a certain direction enters the angle control layer 20 after passing through the light-transmitting member 5, the direction in which the light travels in the angle control layer 20 is the same regardless of the refractive index of the light-transmitting member 5.

[0047] As the value of the refractive index of the angle control layer 20, a value of about 1.5 or more and 1.55 or less is assumed. The value of the refractive index of the angle control layer 20 is, for example, about 1.5. At this time, the light traveling in the air in a direction forming an angle of about 40° with respect to the direction perpendicular to the first surface 10a travels in a direction forming an angle of about 30° with respect to the direction perpendicular to the first surface 10a when it enters the daylighting film 10 according to Snell's law.

[0048] As an example, the case where light traveling in the air enters the daylighting film 10 after passing through the light-transmitting member 5 will be described. As the value of the refractive index of the light-transmitting member 5, a value similar to the value of the refractive index of the components included in the daylighting film 10, particularly the value of the refractive index of the angle control layer 20, is assumed. As an example, as the value of the refractive index of the light-transmitting member 5, a value of about 1.5 or more and 1.55 or less is assumed. When the material of the light-transmitting member 5 is glass, the value of the refractive index of the light-transmitting member 5 is, for example, about 1.5. Assuming that the value of the refractive index of the light-transmitting member 5 is similar to the value of the refractive index of the components included in the daylighting film 10, it is considered that light is not refracted at a large refraction angle at the interface between the light-transmitting member 5 and the daylighting film 10. On the other hand, the light traveling in the air and incident on the daylighting film 10 is considered to be refracted at the interface between the air and the light-transmitting member 5. At this time, since the value of the refractive index of the light-transmitting member 5 is similar to the value of the refractive index of the components included in the daylighting film 10, the light incident at an incident angle of 40° with respect to the surface of the light-transmitting member 5 is refracted so that the refraction angle becomes about 30° at the interface between the air and the light-transmitting member 5. Therefore, the light traveling in the air in a direction forming an angle of 40° with respect to the direction perpendicular to the first surface 10a enters the angle control layer 20 after being refracted so that the refraction angle becomes about 30°, even when the first surface 10a is in contact with the light-transmitting member 5. As described above, when the angle θ1 is 20° or more and 40° or less, the light incident on the first surface 10a from the upper side in the vertical direction and refracted so that the refraction angle becomes about 30° is less likely to be absorbed by the dichroic dye composition 21 of the angle control layer 20. From the above, even when the first surface 10a is in contact with the light-transmitting member 5, by setting the angle θ1 to 20° or more and 40° or less, the light traveling in the air in a direction forming an angle of about 40° with respect to the direction perpendicular to the first surface 10a and incident on the first surface 10a from the upper side in the vertical direction can be introduced into the interior of the building B.

[0049] From the viewpoint of further enhancing the effect of making it difficult to peek into the interior of the building B from below the opening 2, the transmittance T1 is preferably small. The transmittance T1 is preferably 6.0% or less. By setting the transmittance T1 to 6.0% or less, the effect of making it difficult to peek into the interior of the building B from below the opening 2 can be made sufficiently large. More preferably, the transmittance T1 is 5.9% or less.

[0050] From the viewpoint of further enhancing the effect of introducing light from above the opening 2 into the interior of the building B, the transmittance T2 is preferably large. The transmittance T2 is preferably 11.0% or more. By setting the transmittance T2 to 11.0% or more, the effect of introducing light from above the opening 2 into the interior of the building B can be made sufficiently large. More preferably, the transmittance T2 is 12.0% or more, and still more preferably 13.0% or more.

[0051] FIG. 6 is a diagram showing a typical example of a graph showing the results of measuring the transmittance of light transmitted through the daylighting film 10 while changing the incident angle of light with respect to the first surface 10a of the daylighting film 10 according to the present embodiment. The vertical axis of the graph shown in FIG. 6 represents the magnitude of the light transmittance. The horizontal axis of the graph represents the incident angle of light when the incident angle of light with respect to the first surface 10a is changed on a virtual plane perpendicular to the first surface 10a and parallel to the vertical direction. In the graph, the incident angle in the case where light is incident on the first surface 10a from the upper side in the vertical direction is expressed as a positive value. For example, "+40°" on the horizontal axis of the graph corresponds to the case where light is incident on the first surface 10a at an incident angle of about 40° from the upper side in the vertical direction. In the graph, the incident angle in the case where light is incident on the first surface 10a from the lower side in the vertical direction is expressed as a negative value. For example, "-40°" on the horizontal axis of the graph corresponds to the case where light is incident on the first surface 10a at an incident angle of about 40° from the lower side in the vertical direction.

[0052] The inventors of the present invention conducted intensive research and, when measuring the light transmittance of the daylighting film 10 of the present embodiment and creating a graph as shown in FIG. 6, found that the maximum value of the transmittance tended to appear in the range where the incident angle was +30° or more and +40° or less. In other words, the following tendency was found. On a virtual plane perpendicular to the first surface 10a and parallel to the vertical direction, the maximizing light that travels in the direction that maximizes the transmittance when incident on the first surface 10a enters the first surface from above the vertical direction. Furthermore, the incident angle of the maximizing light with respect to the first surface 10a is 30° or more and 40° or less. In the example shown in FIG. 6, the transmittance is maximum when the incident angle is +α° (α is a positive number). +α° is +30° or more and +40° or less. In this case, on a virtual plane perpendicular to the first surface 10a and parallel to the vertical direction, the light that enters the first surface 10a from below the vertical direction at an incident angle of α° with respect to the first surface 10a corresponds to the above-described maximizing light. According to the daylighting film 10 in which such maximizing light enters the first surface from above the vertical direction and the incident angle of the maximizing light with respect to the first surface 10a is 30° or more and 40° or less, the following effect can be obtained. Light that travels in the air in a direction forming an angle of about 30° or more and 40° or less with respect to the direction perpendicular to the first surface 10a and enters the first surface 10a from above the vertical direction can be introduced into the interior of the building B through the daylighting film 10.

[0053] The light transmittance such as transmittance T1 and transmittance T2 tends to decrease as the mass% concentration of the dichroic dye composition 21 in the angle control layer 20 decreases, and tends to increase as the mass% concentration of the dichroic dye composition 21 increases. The mass% concentration of the dichroic dye composition 21 in the angle control layer 20 can be adjusted by adjusting the mass% concentration of the dichroic dye composition 21 in the solution 44 described later. Utilizing this tendency, the mass% concentration of the dichroic dye composition 21 may be adjusted so that the light transmittance such as transmittance T1 and transmittance T2 satisfies the preferable conditions of the above-described light transmittance. The light transmittance such as transmittance T1 and transmittance T2 tends to increase as the film thickness t of the angle control layer 20 described above decreases, and tends to decrease as the film thickness t of the angle control layer 20 increases. Utilizing this tendency, the film thickness t of the angle control layer 20 may be adjusted so that the light transmittance such as transmittance T1 and transmittance T2 satisfies the preferable conditions of the above-described light transmittance.

[0054] The film thickness t of the angle control layer 20 is, for example, 1 μm or more. When the light collection film 10 is fixed to the light-transmitting member 5 such as window glass, etc., the handling of the light collection film 10 becomes easy because the film thickness t is 1 μm or more. The film thickness t of the angle control layer 20 is, for example, 50 μm or less. When the film thickness t is 50 μm or less, it becomes easy to control the orientation of the driving liquid crystal and the polymerizable liquid crystal throughout the angle control layer 20, and to control the orientation of the light absorption axis L2 of the dichroic dye composition 21 throughout the angle control layer 20. Further, from the viewpoint of making the optical performance of the light collection film 10 more preferable, it is more preferable that the film thickness t is 7 μm or more and 15 μm or less.

[0055] An example of the manufacturing method of the light collection film 10 of the present embodiment will be described. FIGS. 7 and 8 are diagrams showing an example of the manufacturing method of the light collection film 10 of the present embodiment. In the manufacture of the light collection film 10, first, as shown in FIG. 7, a first laminate 40a formed by laminating a base material 41, a transparent electrode 42, and an alignment layer 43 in this order is prepared. Further, similarly to the first laminate 40a, a second laminate 40b formed by laminating a base material 41, a transparent electrode 42, and an alignment layer 43 in this order is prepared.

[0056] As the base material 41, various film materials applicable to the base material 41 can be applied as long as they do not interfere with the production of the light collection film 10. The base material 41 has transparency to such an extent that a process of crosslinking the polymerizable liquid crystal by irradiating ultraviolet rays through the first laminate 40a and the second laminate 40b, which will be described later, can be performed. The base material 41 is, for example, a polyethylene terephthalate (PET) film. The base material 41 may be a polycarbonate film, a COP (cyclic olefin polymer) film, a TAC film, or the like.

[0057] As the transparent electrode 42, various electrode materials applicable to the transparent electrode 42 can be applied as long as they do not interfere with the production of the light collection film 10. The transparent electrode 42 has transparency to such an extent that a process of crosslinking the polymerizable liquid crystal by irradiating ultraviolet rays through the first laminate 40a and the second laminate 40b, which will be described later, can be performed. The transparent electrode 42 is, for example, a transparent electrode material made of ITO (Indium Tin Oxide).

[0058] The alignment layer 43 is a layer that regulates the alignment of the liquid crystal composition 22. As the configuration of the alignment layer 43, various configurations capable of exhibiting an alignment regulating force with respect to the liquid crystal composition 22 can be applied. The direction in which the alignment layer 43 aligns the liquid crystal composition 22 is also referred to as the alignment direction. As an example, the alignment layer 43 is produced by rubbing a polyimide resin layer. The alignment layer 43 may be produced by subjecting a so-called photo-alignment film material layer to a photo-alignment treatment.

[0059] Next, a solution 44 that serves as a material for the angle control layer 20 is applied onto the surface of the first laminate 40a that is formed by the alignment layer 43. The solution 44 contains a dichroic dye composition 21 and a liquid crystal composition 22. The liquid crystal composition 22 contains a polymerizable liquid crystal and a driving liquid crystal. As an example, the liquid crystal composition 22 contained in the solution 44 has a rod-like shape. By including the polymerizable liquid crystal and the driving liquid crystal in the liquid crystal composition 22, the following effects can be obtained. Since the liquid crystal composition 22 contains the driving liquid crystal, by applying a voltage to the solution 44 to change the orientation of the driving liquid crystal as described later, the orientation of the light absorption axis L2 of the polymerizable liquid crystal and the dichroic dye composition 21 can be adjusted. Thereby, the orientation of the light absorption axis L2 of the dichroic dye composition 21 can be controlled with high precision. By including the polymerizable liquid crystal in the liquid crystal composition 22, as described later, the polymerizable liquid crystal can be crosslinked to form a cured angle control layer 20. Since the angle control layer 20 is cured, construction work using the daylighting film 10 and work of glass processing described later can be facilitated. Furthermore, by including the driving liquid crystal and the polymerizable liquid crystal in the liquid crystal composition 22, the product price of the daylighting film 10 can be suppressed at a lower cost compared to the case where the liquid crystal composition 22 contains the driving liquid crystal but does not contain the polymerizable liquid crystal. As the dichroic dye composition 21, various materials applicable as long as they do not prevent the daylighting film 10 to be manufactured from exhibiting its effects can be widely applied. As the dichroic dye composition 21, an azo-based dye or an anthraquinone-based dye can be applied. Considering the characteristic surface as the dichroic dye, it is preferable to apply an azo-based dye as the dichroic dye composition 21. Considering weather resistance, it is preferable to apply an anthraquinone-based dye as the dichroic dye composition 21. As the polymerizable liquid crystal and the driving liquid crystal contained in the liquid crystal composition 22, various materials applicable without preventing the daylighting film 10 to be manufactured from exhibiting its effects can be widely applied. The dichroic dye composition 21 and the liquid crystal composition 22 contained in the solution 44 become the dichroic dye composition 21 and the liquid crystal composition 22 contained in the angle control layer 20 of the daylighting film 10 to be manufactured.

[0060] The mass ratio of the polymerizable liquid crystal to the driving liquid crystal contained in the liquid crystal composition 22 is, for example, 7:3. The mass% concentration of the dichroic dye composition 21 in the solution 44 is, for example, 1% or more and 7% or less. The mass% concentration of the dichroic dye composition 21 is, for example, 5%.

[0061] The solution 44 is applied onto the surface of the first laminate 40a in a state of having fluidity by heating. In the example shown in FIG. 7, a hot plate 51 is disposed at a position facing the surface of the first laminate 40a formed by the base material 41. Due to the heating by the hot plate 51, the solution 44 applied onto the surface of the first laminate 40a has fluidity.

[0062] In the example shown in FIG. 7, the solution 44 further contains particles 45. The particles 45 ensure the thickness of the layer formed by the solution 44 when the solution 44 is sandwiched between the first laminate 40a and the second laminate 40b as described later. By ensuring the thickness of the layer formed by the solution 44 by the particles 45, the film thickness t of the angle control layer 20 in the produced light collection film 10 can be ensured. Further, by adjusting the size of the particles 45, the film thickness t of the angle control layer 20 can be adjusted. For example, by making the particle diameter of the particles 45 the same as the film thickness t of the angle control layer 20 of the light collection film 10 to be produced, the angle control layer 20 having a desired film thickness t can be formed. Specifically, by making the particle diameter of the particles 45 10 μm, the angle control layer 20 having a film thickness t of 10 μm can be formed.

[0063] Next, as shown in FIG. 7, the surface of the second laminate 40b formed by the alignment layer 43 is brought into contact with the solution 44. Thereby, the first laminate 40a and the second laminate 40b are overlapped, and the solution 44 is sandwiched between the first laminate 40a and the second laminate 40b. At this time, in the observation from the thickness direction of the first laminate 40a and the second laminate 40b, the first laminate 40a and the second laminate 40b are overlapped so that the alignment direction of the alignment layer 43 of the first laminate 40a and the alignment direction of the alignment layer 43 of the second laminate 40b are parallel. Thereby, in a state where no voltage is applied to the solution 44, the liquid crystal composition 22 is arranged in the solution 44 as described below. The liquid crystal composition 22 is oriented in a direction parallel to the surfaces of the first laminate 40a and the second laminate 40b. Further, the liquid crystal composition 22 is oriented in the alignment direction of the alignment layer 43. In this way, a state is formed in which the solution 44 is sandwiched between the first laminate 40a and the second laminate 40b.

[0064] Next, a voltage is applied between the transparent electrode 42 of the first laminate 40a and the transparent electrode 42 of the second laminate 40b. By applying the voltage, the electric field of the solution 44 changes, and the orientation of the driving liquid crystal contained in the liquid crystal composition 22 changes. At this time, the orientation of the driving liquid crystal changes so as to change the angle formed by the orientation of the driving liquid crystal with respect to the surfaces of the first laminate 40a and the second laminate 40b about a rotation axis parallel to the surfaces of the first laminate 40a and the second laminate 40b and perpendicular to the alignment direction of the alignment layer 43. When the applied voltage is increased, the angle formed by the orientation of the driving liquid crystal with respect to the surfaces of the first laminate 40a and the second laminate 40b becomes larger with 90° as the upper limit.

[0065] When the orientation of the driving liquid crystal changes, the polymerizable liquid crystal contained in the liquid crystal composition 22 is also oriented in the same direction as the driving liquid crystal by being driven by the driving liquid crystal. Thus, when the orientations of the driving liquid crystal and the polymerizable liquid crystal change, the light absorption axis L2 of the dichroic dye composition 21 is also oriented in the same direction as the driving liquid crystal and the polymerizable liquid crystal by being driven by the driving liquid crystal and the polymerizable liquid crystal. As described above, by adjusting the magnitude of the applied voltage, the orientation of the light absorption axis L2 of the dichroic dye composition 21 in the solution 44 can be adjusted.

[0066] The magnitude of the voltage applied between the transparent electrode 42 of the first laminate 40a and the transparent electrode 42 of the second laminate 40b is adjusted so that the above-described angle θ1 is 20° or more and 40° or less in the produced light-collecting film 10. As an example, the magnitude of the applied voltage is adjusted so that the angle formed by the light absorption axis L2 of the dichroic dye composition 21 in the solution 44 with respect to the thickness direction of the first laminate 40a and the second laminate 40b is 20° or more and 40° or less. Thereby, the light-collecting film 10 in which the above-described angle θ1 is 20° or more and 40° or less can be manufactured.

[0067] Next, the polymerizable liquid crystal in the solution 44 is crosslinked by irradiating the solution 44 with ultraviolet rays while maintaining the temperature of the solution 44. In the example shown in FIG. 8, an irradiation device 52 for irradiating ultraviolet rays is disposed at a position facing the surface formed by the base material 41 of the first laminate 40a and at a position facing the surface formed by the base material 41 of the second laminate 40b. By irradiating the solution 44 with ultraviolet rays through the first laminate 40a and the second laminate 40b using the irradiation device 52 arranged in this way, the polymerizable liquid crystal in the solution 44 is crosslinked. As the solution 44 loses fluidity and the polymerizable liquid crystal in the solution 44 is crosslinked, the angle control layer 20 is formed from the solution 44. When the polymerizable liquid crystal is crosslinked, as described above with respect to the angle control layer 20, the dichroic dye composition 21 is incorporated into the structure formed by the crosslinking of the polymerizable liquid crystal. Thereby, in the formed angle control layer 20, the movement of the dichroic dye composition 21 is restricted. Further, the driving liquid crystal is incorporated into the structure formed by the crosslinking of the polymerizable liquid crystal. Thereby, in the formed angle control layer 20, the movement of the driving liquid crystal is restricted.

[0068] Thereafter, the light collection film 10 is manufactured from a state where the angle control layer 20 is formed between the first laminate 40a and the second laminate 40b. In this step, first, one side of the first laminate 40a or the second laminate 40b is peeled off from the formed angle control layer 20. As a result, one of the surfaces of the angle control layer 20 becomes a peeled surface from which the first laminate 40a or the second laminate 40b is peeled off. Then, the adhesive layer 30 is bonded to the peeled surface of the angle control layer 20. Thereafter, while the bonding of the first laminate 40a or the second laminate 40b to the angle control layer 20 is maintained, the side is peeled off from the angle control layer 20. Thus, the light collection film 10 shown in FIG. 3 can be manufactured. The orientation in which the manufactured light collection film 10 is placed is determined such that the transmittance T1 is greater than the transmittance T2 in consideration of the orientation of the light absorption axis L2 of the dichroic dye composition 21 in the angle control layer 20. Further, the orientation in which the light collection film 10 is placed is determined such that the light absorption axis L2 of the dichroic dye composition 21 extends upward in the vertical direction as it goes from the second surface 10b to the first surface 10a in an observation from a direction perpendicular to the above-described virtual plane. The orientation in which the light collection film 10 is placed may be determined such that the light transmittance such as the transmittance T1 and the transmittance T2 satisfies the above-described preferable conditions for the light transmittance. In the present embodiment, the orientation in which the light collection film 10 is placed is determined such that the line segment formed by the intersection of the plane parallel to the orientation of the light absorption axis L2 of the dichroic dye composition 21 and the first surface 10a faces the vertical direction.

[0069] The daylighting film 10 of the present embodiment described above has a first surface 10a and a second surface 10b located on the side opposite to the first surface 10a, and is placed so that the first surface 10a extends in the vertical direction. On a virtual plane perpendicular to the first surface 10a and parallel to the vertical direction, the transmittance T1 of light incident on the first surface 10a from the lower side in the vertical direction at an incident angle of 40° with respect to the first surface 10a is smaller than the transmittance T2 of light incident on the first surface 10a from the upper side in the vertical direction at an incident angle of 40° with respect to the first surface 10a. The daylighting film 10 includes a dichroic dye composition 21 and a liquid crystal composition 22, and includes an angle control layer 20 for controlling the angle at which light passes through. In an observation from a direction perpendicular to the virtual plane, the light absorption axis L2 of the dichroic dye composition 21 is inclined with respect to the first surface 10a and extends upward in the vertical direction as it goes from the second surface 10b toward the first surface 10a. The angle θ1 formed by the light absorption axis L2 of the dichroic dye composition 21 with respect to the direction perpendicular to the first surface 10a is 20° or more and 40° or less. As described above, while making it difficult to peek into the interior of the building B from the lower side of the opening 2, light from the upper side of the opening 2 can be taken into the interior of the building B.

[0070] In an example of the present embodiment, the daylighting film 10 further includes an adhesive layer 30 that constitutes the first surface 10a of the daylighting film 10. Thereby, the daylighting film 10 can be adhered onto the surface of the light-transmitting member 5. The daylighting film 10 may not include the adhesive layer 30. When the light-transmitting member 5 is glass, the laminate 3 including the daylighting film 10 and the light-transmitting member 5 can be manufactured by glass processing. That is, the laminate 3 including the daylighting film 10 and the light-transmitting member 5 which is glass can be manufactured by a laminated glass processing method in which glass / intermediate film / angle control layer 20 / intermediate film / glass are laminated in this order and then heat-pressed. As the intermediate film, PVB (polyvinyl butyral), EVA (ethylene vinyl acetate copolymer resin), or the like is used.

[0071] The laminate 3 of the present embodiment includes the daylighting film 10 and a light-transmitting member 5 superimposed on the daylighting film 10. Thereby, while making it difficult to peek into the interior of the building B from the lower side of the opening 2, light from the upper side of the opening 2 can be taken into the interior of the building B.

[0072] The building B of this embodiment includes an opening 2 and a laminate 3 fitted into the opening 2. As a result, while making it difficult to peek inside the building B from below the opening 2, light from above the opening 2 can be taken into the interior of the building B.

[0073] <Modification Example> Next, with reference to FIGS. 9 to 12, various modification examples of this embodiment will be described. In FIGS. 9 to 12, the same parts as those shown in FIGS. 1 to 8 are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0074] <Modification Example 1> The layer structure of the light collection film 10 is not limited to the example described in the above embodiment. FIG. 9 is a cross-sectional view showing an example of the layer structure of the light collection film 10 of Modification Example 1. In the example shown in FIG. 9, the light collection film 10 includes an angle control layer 20, an alignment layer 43, and a base material 41. In the example shown in FIG. 9, the light collection film 10 further includes a transparent electrode 42. In the example shown in FIG. 9, the angle control layer 20, the alignment layer 43, the transparent electrode 42, and the base material 41 of the light collection film 10 are laminated in this order.

[0075] Regarding the description of the base material 41, the transparent electrode 42, and the alignment layer 43 included in the light collection film 10 in the example shown in FIG. 9, as long as there is no contradiction, the description of the base material 41, the transparent electrode 42, and the alignment layer 43 in the manufacturing method of the light collection film 10 in the above embodiment can be applied.

[0076] The base material 41 can function as a member that supports layers other than the base material 41 included in the daylighting film 10. When the daylighting film 10 includes the base material 41, the material of the base material 41 is not particularly limited as long as it does not prevent the daylighting film 10 from exerting its effect of making it difficult to peek into the interior of the building B while allowing light from the outside of the building B to enter the interior of the building B. The material of the base material 41 has transparency to such an extent that light from the outside of the building B can be taken into the interior of the building B by the daylighting film 10. When the daylighting film 10 includes the base material 41, the base material 41 is, for example, a polyethylene terephthalate (PET) film.

[0077] The daylighting film 10 shown in FIG. 9 can be manufactured, for example, by the following manufacturing method. In the same manner as described in the above-described embodiment, as shown in FIG. 8, the angle control layer 20 is formed between the alignment layer 43 of the first laminate 40a and the alignment layer 43 of the second laminate 40b. Thereafter, either one of the first laminate 40a and the second laminate 40b is peeled off from the angle control layer 20. Thereby, the daylighting film 10 shown in FIG. 9 can be manufactured.

[0078] FIG. 10 is a cross-sectional view showing another example different from FIG. 9 of the layer structure of the daylighting film 10 of Modification 1. In the example shown in FIG. 10, the daylighting film 10 includes only the angle control layer 20. The daylighting film 10 shown in FIG. 10 can be manufactured, for example, by the following manufacturing method. In the same manner as described in the above-described embodiment, as shown in FIG. 8, the angle control layer 20 is formed between the alignment layer 43 of the first laminate 40a and the alignment layer 43 of the second laminate 40b. Thereafter, both the first laminate 40a and the second laminate 40b are peeled off from the angle control layer 20. Thereby, the daylighting film 10 shown in FIG. 10 can be manufactured.

[0079] Although not shown in the drawings, in the light collection film 10, alignment layers 43 may be provided on both sides of the angle control layer 20. That is, the light collection film 10 may include a pair of alignment layers 43 sandwiching the angle control layer 20. Such a light collection film 10 can be manufactured, for example, by the following manufacturing method. By the same method as described in the above-described embodiment, as shown in FIG. 8, the angle control layer 20 is formed between the alignment layer 43 of the first laminate 40a and the alignment layer 43 of the second laminate 40b. Thereafter, in both the first laminate 40a and the second laminate 40b, the base material 41 and the transparent electrode 42 are peeled off from the alignment layer 43.

[0080] Although not shown in the drawings, the alignment layer 43 may constitute at least one of the first surface 10a and the second surface 10b of the light collection film 10. The alignment layer 43 provided in the light collection film 10 may function as a barrier layer that protects the angle control layer 20.

[0081] When the light collection film 10 includes the alignment layer 43, the material of the alignment layer 43 has transparency to such an extent that light from the outside of the building B can be taken into the inside of the building B by the light collection film 10.

[0082] <Modification 2> The manufacturing method of the light collection film 10 is not limited to the example described in the above-described embodiment. Without applying a voltage as described in the above-described embodiment, the orientation of the driving liquid crystal contained in the liquid crystal composition 22 may be changed by photochemically changing the orientation of the liquid crystal composition 22.

[0083] FIG. 11A is a diagram showing an example of a method for manufacturing the light collection film 10 of Modification 2. In the method for manufacturing the light collection film 10 of Modification 2, first, as shown in FIG. 11A, a solution 44 that becomes a material of the angle control layer 20 is applied onto the surface of the first laminate 70a that is formed by the alignment layer 43. The first laminate 70a of Modification 2 is the same as the first laminate 40a of the above-described embodiment, except that it does not have a transparent electrode 42 and the alignment layer 43 is joined to the substrate 41 without sandwiching the transparent electrode 42 therebetween. That is, the first laminate 70a is formed by laminating the substrate 41 and the alignment layer 43 in this order.

[0084] Next, with the solution 44 applied onto the surface of the first laminate 70a, ultraviolet rays are irradiated onto the alignment layer 43 and the solution 44 from a direction that forms an angle with respect to the thickness direction of the first laminate 70a. In particular, ultraviolet rays that are linearly polarized are irradiated onto the alignment layer 43 and the solution 44 from a direction that forms an angle with respect to the thickness direction of the first laminate 70a. At this time, by adjusting the angle formed by the direction in which the ultraviolet rays are irradiated with respect to the thickness direction of the first laminate 70a, the orientation of the driving liquid crystal contained in the liquid crystal composition 22 can be adjusted. Furthermore, the orientation of the driving liquid crystal contained in the liquid crystal composition 22 can also be adjusted by adjusting the exposure energy amount of the irradiated ultraviolet rays. As the alignment layer 43 used in the method for manufacturing the light collection film 10 of Modification 2, an appropriate one is selected for adjusting the orientation of the driving liquid crystal contained in the liquid crystal composition 22 by the above-described method.

[0085] FIG. 11B is a diagram showing an example of a method for adjusting the angle formed by the direction in which ultraviolet rays are irradiated with respect to the thickness direction of the first laminate 70a and the second laminate 70b. In the example shown in FIG. 11B, the first laminate 70a coated with the solution 44 is wound around a plurality of rollers 81. Furthermore, an irradiation device 82 that irradiates ultraviolet rays is arranged at a position where the ultraviolet rays can be irradiated onto the solution 44 applied onto the surface of the first laminate 70a wound around the plurality of rollers 81. In the example shown in FIG. 11B, by moving the positions of the plurality of rollers 81, the angle θ2 formed by the direction dx in which the ultraviolet rays are irradiated from the irradiation device 82 with respect to the thickness direction of the first laminate 70a can be adjusted.

[0086] By adjusting the orientation of the driving liquid crystal contained in the liquid crystal composition 22 through the step of irradiating the alignment layer 43 and the solution 44 with ultraviolet light, the orientation of the polymerizable liquid crystal contained in the liquid crystal composition 22 can be adjusted. Further, the orientation of the light absorption axis L2 of the dichroic dye composition 21 in the solution 44 can be adjusted. The orientation of the light absorption axis L2 of the dichroic dye composition 21 is adjusted such that the angle formed by the light absorption axis L2 with respect to the thickness direction of the first laminate 70a is 20° or more and 40° or less.

[0087] In the method for manufacturing the light collecting film 10 of Modification 2, instead of performing the steps of applying the solution 44 onto the surface of the first laminate 70a described above and irradiating the alignment layer 43 and the solution 44 with ultraviolet light in this order, the step of irradiating the alignment layer 43 of the first laminate 70a with ultraviolet light and the step of applying the solution 44 onto the surface of the alignment layer 43 may be performed in this order. In this case, in the step of irradiating the alignment layer 43 of the first laminate 70a with ultraviolet light, the alignment layer 43 can be irradiated with ultraviolet light by the same method as the method of irradiating ultraviolet light in the step of irradiating the alignment layer 43 and the solution 44 with ultraviolet light. In the step of applying the solution 44 onto the surface of the alignment layer 43, the solution 44 can be applied onto the surface of the alignment layer 43 by the same method as the application method in the step of applying the solution 44 onto the surface of the first laminate 70a.

[0088] Next, as shown in FIG. 12, the surface of the second laminate 70b formed by the alignment layer 43 is brought into contact with the solution 44. As a result, the first laminate 70a and the second laminate 70b are overlapped, and the solution 44 is sandwiched between the first laminate 70a and the second laminate 70b. The second laminate 70b of Modification 2 is the same as the second laminate 40b of the above-described embodiment, except that it does not have the transparent electrode 42 and the alignment layer 43 is bonded to the base material 41 without sandwiching the transparent electrode 42 therebetween. That is, the second laminate 70b is formed by laminating the base material 41 and the alignment layer 43 in this order. At this time, in the observation from the thickness direction of the first laminate 70a and the second laminate 70b, the first laminate 70a and the second laminate 70b are overlapped so that the alignment direction of the alignment layer 43 of the first laminate 70a and the alignment direction of the alignment layer 43 of the second laminate 70b are parallel. Further, the first laminate 70a and the second laminate 70b are overlapped so that a straight line forming a pretilt angle with respect to the alignment layer 43 of the first laminate 70a and a straight line forming a pretilt angle with respect to the alignment layer 43 of the second laminate 70b are parallel. Thereby, the occurrence of alignment defects of the liquid crystal composition 22 is suppressed.

[0089] Although not shown, when the film thickness t of the angle control layer 20 to be formed is particularly small, the second laminate 70b may not be laminated on the solution 44 applied on the surface of the first laminate 70a. In this case, the solution 44 may not contain the particles 45.

[0090] As described above, in a state where the direction of the light absorption axis L2 of the dichroic dye composition 21 in the solution 44 is adjusted by the step of irradiating the solution 44 with ultraviolet rays, the solution 44 loses its fluidity, and the polymerizable liquid crystal in the solution 44 crosslinks, whereby the angle control layer 20 is formed from the solution 44.

[0091] After that, from the state where the angle control layer 20 is formed between the first laminate 70a and the second laminate 70b (when the second laminate 70b is not used, on the first laminate 70a), the light-collecting film 10 including the angle control layer 20 is manufactured. As this method, the method of manufacturing the light-collecting film 10 from the state where the angle control layer 20 is formed between the first laminate 40a and the second laminate 40b, which was described in the above-described embodiment, can be adopted. Thus, the light-collecting film 10 can be manufactured.

Example

[0092] Next, specific examples of the above-described embodiment and each modification will be described.

[0093] (Example 1) First, the light-collecting film 10 shown in FIG. 9 was manufactured. At this time, first, the first laminate 40a in which the transparent electrode 42 and the alignment layer 43 were laminated in this order as shown in FIG. 7 was prepared. Further, the second laminate 40b in which the base material 41, the transparent electrode 42, and the alignment layer 43 were laminated in this order was prepared. The base material 41 of the first laminate 40a and the second laminate 40b was a PET film. The transparent electrode 42 of the first laminate 40a and the second laminate 40b was a transparent electrode material made of ITO. More specifically, as the base material 41 and the transparent electrode 42, those in which an ITO film was formed on a PET base material manufactured by Gunze Co., Ltd. were used. The alignment layer 43 of the first laminate 40a and the second laminate 40b was a rubbing alignment film for twisted nematic liquid crystal manufactured by Nissan Chemical Industries, Ltd.

[0094] Next, a solution 44, which is a material for the angle control layer 20, was applied onto the surface of the first laminate 40a formed by the alignment layer 43. At this time, the solution 44 was applied onto the surface of the first laminate 40a in a state having fluidity by heating with the hot plate 51 shown in FIG. 7. The solution 44 was assumed to contain the dichroic dye composition 21, the liquid crystal composition 22, and the particles 45. As the dichroic dye composition 21, "S-428" manufactured by Yamamoto Chemical Co., Ltd. was used. The liquid crystal composition 22 was assumed to contain a polymerizable liquid crystal and a driving liquid crystal. The mass ratio of the polymerizable liquid crystal and the driving liquid crystal contained in the liquid crystal composition 22 was 7:3. Specifically, as the polymerizable liquid crystal contained in the liquid crystal composition 22, a rod-shaped liquid crystal was used. As the driving liquid crystal contained in the liquid crystal composition 22, a positive liquid crystal used in a normal twisted nematic liquid crystal display was used. The mass% concentration of the dichroic dye composition 21 in the solution 44 was 5%. As the particles 45, Micropearl (particle diameter: 10 μm) manufactured by Sekisui Chemical Co., Ltd. was used. Thereby, the film thickness t of the angle control layer 20 was adjusted to 10 μm.

[0095] Next, the surface of the second laminate 40b formed by the alignment layer 43 was brought into contact with the solution 44. Thereby, as shown in FIG. 7, the first laminate 40a and the second laminate 40b were overlapped, and the solution 44 was sandwiched between the first laminate 40a and the second laminate 40b.

[0096] Next, a voltage was applied between the transparent electrode 42 of the first laminate 40a and the transparent electrode 42 of the second laminate 40b. Thereby, the orientation of the driving liquid crystal contained in the liquid crystal composition 22 was changed, and the orientation of the polymerizable liquid crystal and the orientation of the light absorption axis L2 of the dichroic dye composition 21 were changed. At this time, the magnitude of the applied voltage was adjusted so that the angle formed by the light absorption axis L2 of the dichroic dye composition 21 in the solution 44 with respect to the thickness direction of the first laminate 40a and the second laminate 40b became 20°.

[0097] Next, while maintaining the temperature of the solution 44, the polymerizable liquid crystal in the solution 44 was crosslinked by irradiating the solution 44 with ultraviolet light using an irradiation device 52 as shown in FIG. 8. The direction in which the light collection film 10 is placed was determined such that the line segment formed by the intersection of the plane parallel to the direction of the light absorption axis L2 of the dichroic dye composition 21 and the first surface 10a faces the vertical direction. Thus, the light collection film 10 with the above-described angle θ1 of 20° was manufactured.

[0098] (Example 2) As Example 2, a light collection film 10 was manufactured in the same manner as in Example 1, except that the magnitude of the voltage applied between the transparent electrode 42 of the first laminate 40a and the transparent electrode 42 of the second laminate 40b was adjusted so that the above-described angle θ1 would be 30°.

[0099] (Example 3) As Example 3, a light collection film 10 was manufactured in the same manner as in Example 1, except that the magnitude of the voltage applied between the transparent electrode 42 of the first laminate 40a and the transparent electrode 42 of the second laminate 40b was adjusted so that the above-described angle θ1 would be 40°.

[0100] (Comparative Example 1) As Comparative Example 1, a light collection film 10 was manufactured in the same manner as in Example 1, except that the magnitude of the voltage applied between the transparent electrode 42 of the first laminate 40a and the transparent electrode 42 of the second laminate 40b was adjusted so that the above-described angle θ1 would be 0°.

[0101] (Comparative Example 2) As Comparative Example 2, a light collection film 10 was manufactured in the same manner as in Example 1, except that the magnitude of the voltage applied between the transparent electrode 42 of the first laminate 40a and the transparent electrode 42 of the second laminate 40b was adjusted so that the above-described angle θ1 would be 10°.

[0102] (Comparative Example 3) As Comparative Example 3, a light collection film 10 was manufactured in the same manner as in Example 1, except that the magnitude of the voltage applied between the transparent electrode 42 of the first laminate 40a and the transparent electrode 42 of the second laminate 40b was adjusted so that the above-described angle θ1 was 18°.

[0103] (Comparative Example 4) As Comparative Example 4, a light collection film 10 was manufactured in the same manner as in Example 1, except that the magnitude of the voltage applied between the transparent electrode 42 of the first laminate 40a and the transparent electrode 42 of the second laminate 40b was adjusted so that the above-described angle θ1 was 50°.

[0104] (Comparative Example 5) As Comparative Example 5, a light collection film 10 was manufactured in the same manner as in Example 1, except that the magnitude of the voltage applied between the transparent electrode 42 of the first laminate 40a and the transparent electrode 42 of the second laminate 40b was adjusted so that the above-described angle θ1 was 60°.

[0105] (Comparative Example 6) As Comparative Example 6, a light collection film 10 was manufactured in the same manner as in Example 1, except that the magnitude of the voltage applied between the transparent electrode 42 of the first laminate 40a and the transparent electrode 42 of the second laminate 40b was adjusted so that the above-described angle θ1 was 70°.

[0106] (Comparative Example 7) As Comparative Example 7, a light collection film 10 was manufactured in the same manner as in Example 1, except that the magnitude of the voltage applied between the transparent electrode 42 of the first laminate 40a and the transparent electrode 42 of the second laminate 40b was adjusted so that the above-described angle θ1 was 80°.

[0107] (Comparative Example 8) As Comparative Example 8, a light collection film 10 was manufactured in the same manner as in Example 1, except that the magnitude of the voltage applied between the transparent electrode 42 of the first laminate 40a and the transparent electrode 42 of the second laminate 40b was adjusted so that the above-described angle θ1 was 90°.

[0108] (Example 4) As Example 4, a light collection film 10 was produced in the same manner as in Example 2, except that the mass% concentration of the dichroic dye composition 21 in the solution 44 was 1.3%.

[0109] (Example 5) As Example 5, a light collection film 10 was produced in the same manner as in Example 2, except that the mass% concentration of the dichroic dye composition 21 in the solution 44 was 2.5%.

[0110] (Example 6) As Example 6, a light collection film 10 was produced in the same manner as in Example 2, except that the film thickness t of the angle control layer 20 was adjusted to 5 μm by selecting the particles 45 to be included in the solution 44.

[0111] (Example 7) As Example 7, a light collection film 10 was produced in the same manner as in Example 2, except that the film thickness t of the angle control layer 20 was adjusted to 7 μm by selecting the particles 45 to be included in the solution 44.

[0112] (Example 8) As Example 8, a light collection film 10 was produced in the same manner as in Example 2, except that the film thickness t of the angle control layer 20 was adjusted to 15 μm by selecting the particles 45 to be included in the solution 44.

[0113] (Example 9) As Example 9, a light collection film 10 was produced in the same manner as in Example 2, except that the film thickness t of the angle control layer 20 was adjusted to 20 μm by selecting the particles 45 to be included in the solution 44.

[0114] (1) Measurement test of transmittance Next, a transmittance measurement test was conducted on the daylighting films 10 of Examples 1 to 9 and Comparative Examples 1 to 8. In the transmittance measurement test, with the first surface 10a of the daylighting film 10 in contact with air, the transmittance of the light traveling in the air and incident on the first surface 10a was measured. The light transmittance was measured using a visual angle characteristic measurement and evaluation device (manufactured by ELDIM, product name "EZContrast") as the measurement device. More specifically, the light transmittance was measured by the following method. The sample to be measured was placed at the position where the sample of the measurement device is installed, which is on the surface light source such as a light table. Next, light was irradiated so as to pass through the sample from the light source and reach the detection unit of the measurement device, and the luminance of the light reaching the detection unit was measured. Further, with nothing placed at the position where the sample of the measurement device is installed, light was irradiated from the same light source, and the luminance of the light reaching the detection unit was measured. The transmittance was calculated as the ratio of the luminance when the sample to be measured was placed to the luminance when nothing was placed at the position where the sample of the measurement device was installed. By the above, the above-described transmittance T1 and transmittance T2 were measured. Regarding the daylighting films 10 of Example 2 and Examples 4 to 9, the transmittance of the light (referred to as transmittance T3) when the incident angle of the light with respect to the first surface 10a was a right angle was also measured. Regarding the daylighting films 10 of Example 2 and Example 4, while continuously changing the incident angle of the light with respect to the first surface 10a, the transmittance of the light passing through the daylighting film 10 was measured.

[0115] (2) Sensory evaluation test of ease of light intake and difficulty of being seen through Next, a sensory evaluation test of ease of light intake and difficulty of being seen through was conducted on the daylighting films 10 of Examples 1 to 3 and Comparative Examples 1 to 8.

[0116] In the sensory evaluation test of the ease of light intake and the difficulty of peeping, the daylighting film 10 was bonded to the window glass of the window provided on the second floor of the building B. The periphery of the portion of the window glass to which the daylighting film 10 was bonded was shielded from light by installing a film that does not transmit light. That is, using the window glass as the light-transmitting member 5, a laminate 3 including the daylighting film 10 and the light-transmitting member 5 was manufactured. The width of the window glass in the horizontal direction was 10 cm. The width of the window glass in the vertical direction was 10 cm. The daylighting film 10 was attached to the window glass so that the first surface 10a faced the outside of the building B from the inside of the building B. The surface of the window glass was parallel to the vertical direction. For this reason, the first surface 10a of the daylighting film 10 attached to the window glass was parallel to the vertical direction.

[0117] The sensory evaluation test was conducted during the period from March 1 to March 7 on a clear day in Japan, during the daytime including noon. The sensory evaluation test was conducted with the lighting in the room where the window glass with the daylighting film 10 attached was provided turned off.

[0118] In the sensory evaluation of the ease of light intake, the subject was made to stand in the room of the building B where the window glass with the daylighting film 10 attached was provided. Then, the subject was made to evaluate the brightness in the said room. When the subject felt sufficient light intensity even during the daytime other than noon when reading the characters written in a general book, the ease of light intake was evaluated as "◎". When there was a time zone where the light intensity was felt to be insufficient during the daytime other than noon when the subject read the characters written in a general book, but sufficient light intensity was felt at noon, the ease of light intake was evaluated as "○". When the subject felt a slight lack of light amount at noon when reading the characters written in a general book, the ease of light intake was evaluated as "△". When the subject felt a lack of light amount at noon when reading the characters written in a general book, the ease of light intake was evaluated as "×".

[0119] In the sensory evaluation of the difficulty of peeking, the subject was made to stand at a position facing the window glass on the outside of Building B. The horizontal distance between the wall provided with the window glass and the subject was set to 2 m. Then, the subject was asked to evaluate how much of the inside of Building B could be seen through the window glass and the daylighting film 10. When the subject peeked into the inside of Building B through the window glass and the daylighting film 10 and the inside could not be confirmed, the difficulty of peeking was evaluated as "○". When the subject peeked into the inside of Building B through the window glass and the daylighting film 10 and the inside could be confirmed, the difficulty of peeking was evaluated as "×".

[0120] Table 1 shows the results of the transmittance measurement tests for the daylighting films 10 of Examples 1 to 3 and Comparative Examples 1 to 8, as well as the results of the sensory evaluation tests for the ease of light intake and the difficulty of peeking.

[0121]

Table 1

[0122] From the results shown in Table 1, it was found that in Examples 1 to 3 where the angle θ1 is 20° or more and 40° or less, the value of T2 / T1 can be increased. In particular, under the conditions of Examples 1 to 3 and Comparative Examples 1 to 8, it was found that when the angle θ1 is 20° or more and 40° or less, the value of T2 / T1 can be made 1.85 or more. Furthermore, from the results shown in Table 1, it was found that in Examples 1 to 3 where the angle θ1 is 20° or more and 40° or less, in the sensory evaluation test, the ease of light intake was evaluated as "◎" and the difficulty of peeking was evaluated as "○".

[0123] Table 2 shows the results of the transmittance measurement tests for the light-guiding films 10 of Example 2, Example 4, and Example 5. Regarding the light-guiding films 10 of Example 2 and Example 4, FIG. 13 shows the results of measuring the transmittance of the light passing through the light-guiding film 10 while continuously changing the incident angle of light with respect to the first surface 10a. The vertical axis of the graph shown in FIG. 13 represents the magnitude of the light transmittance. The horizontal axis of the graph represents the incident angle of light when changing the incident angle of light with respect to the first surface 10a on a virtual plane perpendicular to the first surface 10a and parallel to the vertical direction. In the graph, the incident angle when light is incident on the first surface 10a from the upper side in the vertical direction is expressed as a positive value. In the graph, the incident angle when light is incident on the first surface 10a from the lower side in the vertical direction is expressed as a negative value.

[0124]

Table 2

[0125] From the results shown in Table 2 and FIG. 13, it was found that by adjusting the mass% concentration of the dichroic dye composition 21, the transmittance T1, the transmittance T2, and the transmittance T3 can be adjusted. In particular, it was found that the transmittance T1, the transmittance T2, and the transmittance T3 decrease as the mass% concentration of the dichroic dye composition 21 decreases, and increase as the mass% concentration of the dichroic dye composition 21 increases.

[0126] From the results shown in FIG. 13, it was found that in Example 4 with a mass% concentration of 1.3% of the dichroic dye composition 21, the change in transmittance was greater when measuring the transmittance of light while changing the incident angle of light with respect to the first surface 10a, compared to Example 2 with a mass% concentration of 5% of the dichroic dye composition 21. From the results shown in FIG. 13, it was found that in both Example 2 and Example 4, the maximum value of the transmittance appeared in the range where the incident angle was +30° or more and +40° or less.

[0127] Table 3 shows the results of the transmittance measurement tests for the light-guiding films 10 of Example 2 and Examples 6 to 9.

[0128]

Table 3

[0129] From the results shown in Table 3, it was found that the transmittance T1, transmittance T2, and transmittance T3 can be adjusted by adjusting the film thickness t of the angle control layer 20. In particular, it was found that the transmittance T1, transmittance T2, and transmittance T3 increase when the film thickness t of the angle control layer 20 is decreased, and decrease when the film thickness t of the angle control layer 20 is increased.

[0130] It is also possible to appropriately combine a plurality of components disclosed in the above embodiments and each modification as needed. Alternatively, some components may be deleted from all the components shown in the above embodiments and each modification.

Explanation of Reference Numerals

[0131] 2 Opening 3 Laminate 4 Wall 5 Light-transmitting member 10 Lighting film 10a First surface 10b Second surface 20 Angle control layer 21 Dichroic dye composition 22 Liquid crystal composition 30 Adhesive layer 31 Second unit lens 40a First laminate 40b Second laminate 41 Substrate 42 Transparent electrode 43 Alignment layer B Building

Claims

1. A light collection film having a first surface and a second surface located on the side opposite to the first surface, and being placed such that the first surface extends in the vertical direction, wherein on a virtual plane perpendicular to the first surface and parallel to the vertical direction, the transmittance T1 of light incident on the first surface from the lower side of the vertical direction at an incident angle of 40° with respect to the first surface is smaller than the transmittance T2 of light incident on the first surface from the upper side of the vertical direction at an incident angle of 40° with respect to the first surface; comprising a dichroic dye composition and a liquid crystal composition, and provided with an angle control layer for controlling the angle at which light passes through; in observation from a direction perpendicular to the virtual plane, the light absorption axis of the dichroic dye composition is inclined with respect to the first surface and extends upward in the vertical direction from the second surface toward the first surface; A light collection film, wherein the angle formed by the light absorption axis of the dichroic dye composition with respect to the direction perpendicular to the first surface is 20° or more and 40° or less.

2. The light collection film according to Claim 1, wherein the value obtained by dividing the transmittance T2 by the transmittance T1 is 1.85 or more.

3. The light collection film according to Claim 1, wherein the transmittance T1 is 6% or less.

4. The light collection film according to Claim 1, wherein the transmittance T2 is 11% or more.

5. On the virtual plane, the maximizing light that travels in the direction that maximizes the transmittance when incident on the first surface is incident on the first surface from the upper side of the vertical direction, The light collection film according to Claim 1, wherein the incident angle of the maximizing light with respect to the first surface is 30° or more and 40° or less.

6. The light collection film according to Claim 1, further comprising an adhesive layer that constitutes the first surface of the light collection film.

7. A light collection film according to any one of Claims 1 to 6, and a light-transmitting member laminated on the light collection film, A laminate fitted into an opening of a building.

8. An opening, and A building comprising the laminate according to Claim 7 fitted into the opening.

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