Light control film

Abstract

To achieve an improvement in appearance quality of a light control film.SOLUTION: A light control film has a laminate 11 formed such that polarization films 15A and 15B are stacked on a film base material 12. The film base material 12 has one surface in a thickness direction as a surface 13 to be stacked. The polarization films 15A and 15B have one surfaces in the thickness direction as front surfaces 21A and 21B, have the other surfaces as rear surfaces 22A and 22B, and have side surfaces 23A and 23B on both sides in a first direction. A direction orthogonal to the thickness direction and the first direction is defined as a second direction. In the laminate 11, the polarization films 15A and 15B are disposed in a staggered manner in the first direction, and rear surfaces thereof 22A and 22B are bonded on the surface 13 to be stacked. A cavity part 26 extending over an entire length of the polarization films 15A and 15B in the second direction is formed between the adjacent side surfaces 23A and 23B and the surface 13 to be stacked. The adjacent front surfaces 21A and 21B come into contact with each other.SELECTED DRAWING: Figure 16

Description

[Technical field]

[0001] The present invention relates to a light control film for use in a light control device. [Background technology]

[0002] A light control device is known that includes a pair of light control films arranged facing each other in the thickness direction. In this light control device, the light transmittance of both light control films is adjusted by displacing the two light control films relatively in a first direction perpendicular to the thickness direction (see, for example, Patent Document 1).

[0003] Fig. 20 shows a part of one of the light control films 70. The light control film 70 comprises a film substrate 71, and a plurality of first polarizing films 75A and a plurality of second polarizing films 75B, each laminated in the thickness direction of the film substrate 71. In Fig. 20, the up-down direction and the left-right direction are the "thickness direction" and the "first direction", respectively. Here, the direction perpendicular to both the thickness direction and the first direction, that is, the direction perpendicular to the paper surface in Fig. 20, is the second direction.

[0004] The film substrate 71 has one surface in the thickness direction as a surface 72 to be laminated. Each of the first polarizing films 75A has one surface in the thickness direction as a front surface 76A and the other surface as a back surface 77A. Each of the first polarizing films 75A has side surfaces 78A on both sides in the first direction. The entire surface of each side surface 78A extends in the thickness direction.

[0005] Each second polarizing film 75B has one surface in the thickness direction as a front surface 76B and the other surface as a back surface 77B. Each second polarizing film 75B has side surfaces 78B on both sides in the first direction. The entire surface of each side surface 78B extends in the thickness direction.

[0006] Each of the first polarizing films 75A and each of the second polarizing films 75B has a rectangular shape whose dimension in the second direction is longer than its dimension in the first direction. Each of the first polarizing films 75A and each of the second polarizing films 75B has a polarization axis (not shown) extending in a different direction from each other.

[0007] In manufacturing the light control film 70, for example, a plurality of first polarizing films 75A and a plurality of second polarizing films 75B are laminated to the laminated surface 72 in a state of being arranged alternately in the first direction. For example, when the object to be laminated is the second polarizing film 75B shown by the two-dot chain line in FIG. 20, foreign matter EM such as air bubbles and dust may enter between the back surface 77B and the laminated surface 72 during the lamination. To cope with this, a pressing member PM such as a spatula or roller is moved while being pressed against the second polarizing film 75B. By this movement, the foreign matter EM is moved toward the peripheral portion of the second polarizing film 75B as shown by the two-dot chain arrow in FIG. 20, while the second polarizing film 75B is laminated to the laminated surface 72. The lamination of the first polarizing film 75A is also performed in the same manner as the lamination of the second polarizing film 75B. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 9-310567 Summary of the Invention [Problem to be solved by the invention]

[0009] In the conventional light control film 70, the polarizing films 75A and 75B are bonded together so that the side 78A and the adjacent side 78B are in close contact with each other. Therefore, even if the foreign matter EM is moved between the adjacent side surfaces 78A and 78B or close to the space between them, the foreign matter EM remains between the back surfaces 77A and 77B and the laminated surface 72. It is difficult to remove the foreign matter EM.

[0010] Furthermore, even if one attempts to remove the foreign matter EM by moving it in the second direction, if the distance from the foreign matter EM to the end face in the second direction of the polarizing films 75A and 75B to be attached is long, it is difficult to move the foreign matter EM to the end face.

[0011] As a result, the foreign matter EM is likely to remain between the rear surfaces 77A, 77B and the laminated surface 72. If the foreign matter EM remains, it will be visible from the outside of the light-controlling film 70, and the appearance quality of the light-controlling film 70 will deteriorate.

[0012] When the adjacent polarizing films 75A, 75B are attached to the laminated surface 72 while being spaced apart in the first direction, it is possible to move the foreign matter EM into the gap between the adjacent side surfaces 78A, 78B and remove it. However, in this case, the gap between the adjacent surfaces 76A, 76B is visible from the outside of the light control film 70. In this case, too, the appearance quality of the light control film 70 is reduced due to the gap. [Means for solving the problem]

[0013] Various aspects of the light control film for solving the above problems will be described below. [Aspect 1] In a light control device having a pair of light control elements arranged opposite to each other in a thickness direction, and adjusting the amount of light transmitted through both light control elements by relatively displacing both light control elements in a first direction perpendicular to the thickness direction, a light control film used as the light control element has a laminate formed by laminating two types of polarizing films on a film substrate, the film substrate has one surface in the thickness direction as a surface to be laminated, each polarizing film has one surface in the thickness direction as a front surface and the other surface as a back surface, and has side surfaces on both sides in the first direction, A light-controlling film, in which the polarizing film is in the form of a strip whose dimension in a second direction perpendicular to both the thickness direction and the first direction is longer than the dimension in the first direction, and has polarization axes extending in different directions from each other, and in the laminate, two types of polarizing films are arranged alternately in the first direction and bonded to the laminated surface at their back surfaces, and in adjacent polarizing films, a cavity extending over the entire length of the polarizing film in the second direction is formed between adjacent pairs of side surfaces and the laminated surface, and the surfaces of adjacent polarizing films are in contact with each other.

[0014] According to the above configuration, when manufacturing the light control film, two types of polarizing films are laminated to a surface to be laminated while being arranged alternately in the first direction. With this lamination, a cavity is formed between the side of the polarizing film already laminated, the side of the polarizing film to be laminated, and the surface to be laminated.

[0015] On the other hand, when laminating the polarizing film, foreign matter such as air bubbles or dust may get between the back surface of the polarizing film and the surface to be laminated. To deal with this, a pressing member such as a spatula or roller is moved while being pressed against the polarizing film. By this movement, the polarizing film is laminated to the surface to be laminated while moving the foreign matter toward the cavity.

[0016] The cavity is formed at a location adjacent to the polarizing film attached to the film substrate in the first direction, and therefore, when the foreign matter is moved to the cavity, it does not remain between the rear surface of the polarizing film and the laminated surface.

[0017] The cavity extends over the entire length of the polarizing film in the second direction. Moreover, a cavity is formed between each pair of adjacent side surfaces of adjacent polarizing films. The dimension of each polarizing film in the second direction is longer than the dimension in the first direction.

[0018] Therefore, when the polarizing film is bonded to the surface to be laminated, even if a foreign object enters anywhere in the second direction between the back surface and the surface to be laminated, it is possible to move the foreign object to the hollow portion by simply moving it a short distance.

[0019] In the light control film having the laminate obtained as described above, no foreign matter remains between the back surface of each polarizing film and the surface to be laminated, and therefore, no foreign matter can be seen from the outside of the light control film through the polarizing film.

[0020] In addition, the surfaces of adjacent polarizing films are in contact with each other, so that the gap between the adjacent surfaces is not visible or is difficult to see from the outside of the light control film. [Aspect 2] A light-controlling film as described in [Aspect 1], wherein, of the side surfaces of each polarizing film, the side surface facing the adjacent polarizing film is inclined with respect to the thickness direction so that the angle it forms with the surface is an acute angle.

[0021] Here, among the side surfaces of each polarizing film, the side surface on the side of the adjacent polarizing film affects the shape of the cavity. According to the above configuration, the side surface is inclined in the thickness direction so that the angle with respect to the surface of the polarizing film is an acute angle. Therefore, the shape of the cavity has a dimension in the first direction that increases toward the laminated surface. Therefore, compared to a case where the dimension of the cavity in the first direction is not maximum at the laminated surface, it is possible to accurately push out foreign matter from between the back surface and the laminated surface into the cavity.

[0022] [Aspect 3] A light-control film according to aspect 1 or aspect 2, wherein the cavity is formed so that the dimension in the first direction is 500 μm or less. With the above configuration, when the dimension of the cavity in the first direction is 500 μm or less, the cavity is difficult to see from the outside of the light control film.

[0023] [Aspect 4] A light-controlling film described in any one of [Aspect 1] to [Aspect 3], wherein each polarizing film is formed by laser cutting, and the side surface inclined relative to the thickness direction is constituted by a cut surface resulting from the laser cutting.

[0024] According to the above configuration, each polarizing film is formed by laser cutting. This laser cutting can produce a cut surface inclined with respect to the thickness direction in the polarizing film. This cut surface becomes a side surface inclined with respect to the thickness direction in each polarizing film. Therefore, cutting and forming the inclined side surface are performed simultaneously, or in other words, in one step. Therefore, a polarizing film having an inclined side surface can be formed with fewer and simpler steps than when forming the polarizing film and forming the inclined side surface in separate steps. Effect of the Invention

[0025] According to the present invention, it is possible to improve the appearance quality of the light control film. [Brief description of the drawings]

[0026] [Figure 1] FIG. 1 is a perspective view of a light control device according to an embodiment. [Diagram 2] FIG. 2 is a perspective view showing a pair of light control films in FIG. 1 in a separated state. [Diagram 3] FIG. 2 is a perspective view showing a laminate and a frame that constitute one of the light control films (the lower side in FIG. 2) in the embodiment, in which the laminate and the frame are separated. [Figure 4] FIG. 4 is a perspective view showing components of the laminate in FIG. 3 separated from one another. [Diagram 5] FIG. 5 is a partial cross-sectional view showing the layer structure of the polarizing film in FIG. [Figure 6] FIG. 2 is a perspective view showing the function-added laminate and the frame that constitute the other light control film (upper side in FIG. 2) in the embodiment, in a separated state. [Figure 7] FIG. 7 is a perspective view showing components of the function-added laminate in FIG. 6 in a separated state. [Figure 8] FIG. 8 is a partial cross-sectional view showing the layer structure of the polarizing film in FIG. [Figure 9] FIG. 2 is a partial cross-sectional view of a laminate in the light control film of the embodiment. [Figure 10] FIG. 2 is a perspective view illustrating a state in which a first polarizing film is formed from a raw material film by laser cutting in the embodiment. [Figure 11] 11 is a perspective view showing a part of a plurality of first polarizing films formed by the laser cutting of FIG. 10, with some omitted. FIG. [Figure 12] FIG. 4 is a perspective view illustrating a state in which a second polarizing film is formed from a raw material film by laser cutting in the embodiment. [Figure 13] 13 is a perspective view showing a part of a plurality of second polarizing films formed by the laser cutting of FIG. 12, with some omitted. FIG. [Figure 14] FIG. 2 is a partial cross-sectional view illustrating how the polarizing film is formed by laser cutting in the embodiment, and how cut surfaces that are inclined with respect to the thickness direction are formed. [Figure 15] FIG. 2 is a perspective view illustrating how a first polarizing film and a second polarizing film are attached to a surface to be laminated of a film substrate in the embodiment. [Figure 16] FIG. 4 is a partial cross-sectional view illustrating how a second polarizing film is attached to a surface to be laminated while a foreign object is being moved into a cavity in the embodiment. [Figure 17] FIG. 11 is a perspective view illustrating how an excess portion is cut and removed from the laminate in the embodiment. [Figure 18]FIG. 13 is a perspective view showing a modified example, illustrating how a polarizing film is attached to a surface to be laminated while a raw material film is being pulled out. [Figure 19] FIG. 13 is a partial perspective view illustrating a modified example, in which the raw film to which the polarizing film is attached is fed by a pair of rollers. [Figure 20] FIG. 1 is a diagram illustrating the prior art, and is a partial cross-sectional view illustrating a state in which foreign matter remains when a polarizing film is attached to a surface of a film substrate to be laminated. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] Hereinafter, one embodiment of a light control film used in a light control device will be described with reference to Figs. 1 and 2, the light control device A includes a pair of light control elements, that is, a pair of light control films 10 and 30. The pair of light control films 10 and 30 are arranged facing each other in their thickness directions (the vertical directions in each of FIGS. 1 and 2), more specifically, overlapping each other.

[0028] Here, a direction perpendicular to the thickness direction of each of the light control films 10 and 30 is defined as a first direction, and a direction perpendicular to both the thickness direction and the first direction is defined as a second direction. The light control device A adjusts the amount of light transmission by displacing the two light control films 10 and 30 relatively in a first direction. In this embodiment, the relative displacement is achieved by sliding only one of the light control films 10 in the first direction.

[0029] <Light Control Film 10> As shown in FIG. 2 and FIG. 3, one of the light control films 10 (lower side of FIG. 2) includes a laminate 11 and a frame 27. The laminate 11 includes a film substrate 12 and two types of polarizing films bonded to the film substrate 12 as components. Here, when it is necessary to distinguish between the two types of polarizing films, one is referred to as a first polarizing film 15A and the other is referred to as a second polarizing film 15B. In addition, in each figure, in order to distinguish between the first polarizing film 15A and the second polarizing film 15B and to make them easier to see, only the former is dotted. The laminate 11 uses a plurality of the first polarizing films 15A and the second polarizing films 15B. When it is not necessary to distinguish between the two types of polarizing films, they are simply referred to as the polarizing films 15A and 15B.

[0030] [Film base material 12] 3 and 4, the film substrate 12 is made of a transparent thermoplastic resin and has flexibility. Examples of the resin include PET (polyethylene terephthalate) resin, PE (polyethylene) resin, PP (polypropylene) resin, ABS (acrylonitrile-butadiene-styrene copolymer) resin, PVA (polyvinyl alcohol) resin, and TAC (triacetyl cellulose) resin.

[0031] The film substrate 12 has a rectangular shape. One surface of the film substrate 12 in the thickness direction, which is the upper surface in Figs. [First polarizing film 15A and second polarizing film 15B] Each of the first polarizing films 15A and each of the second polarizing films 15B is made of a thermoplastic resin different from that of the film substrate 12, and has flexibility. As shown in Fig. 5, each of the first polarizing films 15A and the second polarizing films 15B includes a film body 16 and a pair of transparent protective films 17 that sandwich the film body 16 from both sides in the thickness direction. The film body 16 is made of, for example, a PVA resin dyed with an iodine solution.

[0032] The film body 16 is produced, for example, as follows: A PVA resin film is dyed with iodine. The PVA resin molecules that make up the film are bonded together and stabilized by boric acid. The film is pulled in one direction while still wet. The PVA resin molecules and iodine molecules are oriented in the direction in which they are pulled. When this film is dried, the film body 16 having a polarization axis and polarizing properties is obtained.

[0033] Each protective film 17 is intended to protect the film body 16 from external impact, heat, humidity, etc. Each protective film 17 is made of an optically isotropic material, such as TAC resin. Each protective film 17 is attached to the film body 16.

[0034] As shown in Fig. 4, each of the first polarizing films 15A and each of the second polarizing films 15B is in the form of a strip whose dimension in the second direction is longer than its dimension in the first direction. The dimension in the second direction is set to be the same for the first polarizing film 15A and the second polarizing film 15B. Each of the first polarizing films 15A and each of the second polarizing films 15B has a polarization axis extending in a different direction. In this embodiment, the polarization axis of each of the second polarizing films 15B extends in a direction perpendicular to the polarization axis of each of the first polarizing films 15A.

[0035] 3 to 5, each first polarizing film 15A has one surface in the thickness direction as a front surface 21A and the other surface as a back surface 22A. Each first polarizing film 15A has side surfaces 23A on both sides in the first direction.

[0036] Each second polarizing film 15B has one surface in the thickness direction as a front surface 21B and the other surface as a back surface 22B. Each second polarizing film 15B has side surfaces 23B on both sides in the first direction.

[0037] The first polarizing films 15A and the second polarizing films 15B are arranged alternately in the first direction. The back surface 22A of each of the first polarizing films 15A and the back surface 22B of each of the second polarizing films 15B are joined to the laminated surface 13 by adhesion. In other words, the back surfaces 22A and 22B of each of the polarizing films 15A and 15B are attached to the laminated surface 13.

[0038] In Fig. 4, the layer of adhesive that bonds each of the polarizing films 15A and 15B to the laminated surface 13 is illustrated as an adhesive layer 25. Note that the adhesive layer 25 is illustrated only in Fig. 4 and Fig. 7 which corresponds to Fig. 4. In the other figures, the adhesive layer 25 is omitted.

[0039] 9, a cavity 26 is formed between the adjacent first and second polarizing films 15A and 15B and the film substrate 12, and between the adjacent pair of side surfaces 23A, 23B and the laminated surface 13. The cavity 26 extends over the entire length of the polarizing films 15A and 15B in the second direction.

[0040] The surfaces 21A, 21B of the adjacent first polarizing film 15A and second polarizing film 15B are in contact with each other over the entire length in the second direction. In each first polarizing film 15A, the entire side surface 23A on the second polarizing film 15B side is inclined with respect to the thickness direction so that the angle θA formed with respect to the surface 21A of the first polarizing film 15A is an acute angle.

[0041] Similarly, in each second polarizing film 15B, the entire side surface 23B on the first polarizing film 15A side is inclined with respect to the thickness direction so that the angle θB formed with respect to the surface 21B of the second polarizing film 15B is an acute angle.

[0042] The side surface 23B is inclined toward the opposite side to the side surface 23A. The angle θB is set to be the same as or approximately the same as the angle θA. Therefore, the cross section of the cavity 26 is triangular in which the dimension M1 in the first direction increases toward the film substrate 12. The dimension M1 is maximum at the laminated surface 13. The dimension M1 at the laminated surface 13 is set to be 10 μm or more and 500 μm or less. The condition of 500 μm or less is set from the viewpoint of making the cavity 26 difficult to see. In this embodiment, the dimension M1 at the laminated surface 13 is set to be about 20 μm. Both ends of each cavity 26 in the second direction are not particularly sealed.

[0043] [Frame 27] 3 and 4, the frame 27 is made of a resin material and has a thin rectangular frame shape, and is flexible. The frame 27 is disposed on the opposite side of the laminate 11 to the polarizing films 15A and 15B, across the film substrate 12, that is, on the lower side in FIG. 3. The laminate 11 is attached to the frame 27 from the upper side in FIG. 3.

[0044] <Light Control Film 30> 2 and 6, the other light control film 30 (upper side in FIG. 2) has a similar configuration to the above-mentioned light control film 10. Therefore, in the light control film 30, components common to the light control film 10 are given the same reference numerals, and duplicated explanations are omitted. The light control film 30 will be described focusing on the differences from the light control film 10.

[0045] The light control film 30 has a function-added laminate 31 shown in Figures 6 and 7 as a component corresponding to the laminate 11. The function-added laminate 31 includes the laminate 11, and further includes a low friction layer 32 and a hard coat layer 33. The light control film 30 includes this function-added laminate 31 and a frame 27.

[0046] As shown in Figs. 7 and 8, the rectangular film substrate 12 has one surface in the thickness direction, which is the lower surface in Fig. 8, as a surface 13 to be laminated. The polarizing films 15A and 15B each have one surface in the thickness direction, which is the lower surface in Fig. 8, as the front surface 21A, 21B, and the other surface, which is the upper surface in Fig. 8, as the back surface 22A, 22B. The back surfaces 22A, 22B of the multiple first polarizing films 15A and the multiple second polarizing films 15B arranged alternately in the first direction are joined by adhesion to the laminated surface 13. In other words, the back surfaces 22A, 22B of the polarizing films 15A and 15B are attached to the laminated surface 13.

[0047] In FIG. 7, the layer of adhesive that bonds each of the polarizing films 15A and 15B to the lamination surface 13 of the film substrate 12 is illustrated as an adhesive layer 25. [Low friction layer 32] As shown in Fig. 7 and Fig. 8, the low friction layer 32 is formed on the surfaces 21A, 21B of the polarizing films 15A, 15B. The low friction layer 32 is provided for the purpose of increasing the slipperiness, for example, increasing the sliding property of the light control film 10 relative to the light control film 30, increasing the water repellency, etc. The low friction layer 32 is formed by subjecting the surfaces 21A, 21B to a lubricant treatment, for example, a water repellent coating treatment, a silicone coating treatment, etc. The low friction layer 32 is only shown in Fig. 7 and Fig. 4 (see the two-dot chain line) corresponding to Fig. 7. In other figures, the low friction layer 32 is omitted from the illustration.

[0048] [Hard coat layer 33] 7, the hard coat layer 33 is formed by applying a known surface treatment agent to the surface 14 opposite the laminated surface 13, among both surfaces of the film substrate 12 in the thickness direction. The hard coat layer 33 provides useful effects to the film substrate 12 on which it is formed, such as an effect of suppressing scratches, an effect of making it difficult for dirt to adhere, an effect of improving light resistance and weather resistance by blocking ultraviolet rays, and a water repellent effect.

[0049] 6 and 7, the frame 27 formed of a resin material in a thin rectangular frame shape is disposed on the opposite side of the polarizing films 15A and 15B, or on the upper side in Fig. 6, of the function-added laminate 31, with the film substrate 12 sandwiched therebetween. The function-added laminate 31 is assembled to the frame 27 from the lower side in Fig. 6.

[0050] 2, in the light control device A, the pair of light control films 10 and 30 described above are arranged so that their frames 27 are located at both ends in the thickness direction. The light control film 10 is assembled to the light control film 30 so as to be slidable in the first direction.

[0051] Next, the operation of this embodiment will be described together with a method for manufacturing the light control films 10 and 30. The pair of light control films 10 and 30 are manufactured through similar processes. Therefore, the light control film 10 will be mainly described here. The light control film 30 will be described with a focus on the differences from the light control film 10.

[0052] In manufacturing the light control film 10, a first polarizing film forming step, a second polarizing film forming step, and a laminate forming step are performed. <First polarizing film formation process> As shown in Figs. 10 and 14, in the first polarizing film forming process, a raw material film 41 having a square or rectangular shape close to a square is used. In Fig. 10, the raw material film 41 is dotted corresponding to the above-mentioned first polarizing film 15A. The peripheral portion of this raw material film 41 has a pair of first side portions 42 extending parallel to each other and a pair of second side portions 43 extending in a direction perpendicular to both first side portions 42. Like the first polarizing film 15A and the second polarizing film 15B, the raw material film 41 has a film body having a polarization property and a pair of protective films sandwiching the film body from both sides in the thickness direction. The polarization axis of the raw material film 41 extends in a certain direction, for example, along the first side portions 42.

[0053] The first polarizing film 15A is formed by laser cutting the raw material film 41. During laser cutting, a laser light (laser beam) LB is generated by a laser oscillator and transmitted using a reflecting mirror or the like, and is focused by a focusing lens. The focusing lens is focused on the surface 44 of the raw material film 41. The focused laser light LB is irradiated onto the surface 44 of the raw material film 41.

[0054] As the laser light LB is absorbed, the temperature of the portion of surface 44 of raw material film 41 irradiated with the laser light LB increases. The area of ​​raw material film 41 around the portion (surface 44) irradiated with the laser light LB is heated by thermal conduction, and the temperature increases. The area with the increased temperature softens, melts, evaporates, and is removed.

[0055] The laser beam LB and the raw material film 41 are relatively displaced in a direction along the first side 42, that is, at least one of them is moved linearly in a direction along the first side 42, thereby changing the location on the raw material film 41 that is irradiated with the laser beam LB. This change causes the raw material film 41 to be cut linearly in a direction along the first side 42.

[0056] Here, heat generated by irradiation with the laser beam LB is conducted from the front surface 44 to the back surface 45 of the raw film 41. As a result, the width of the area cut by the laser beam LB is greatest at the front surface 44 and decreases toward the back surface 45. As a result of the cutting, a pair of cut surfaces 46 are created. An angle θ1 that each cut surface 46 makes with respect to the front surface 44 of the raw film 41 is an obtuse angle, and an angle θ2 that each cut surface 46 makes with respect to the back surface 45 is an acute angle.

[0057] Then, cutting is performed from one second side portion 43 to the other second side portion 43. By repeating this cutting multiple times, a plurality of strip-shaped first polarizing films 15A that are longer in the direction along the first side portion 42 than in the direction along the second side portion 43 are formed from one sheet of raw material film 41, as shown in Fig. 11. Cut surfaces 46 (see Fig. 14) created by the laser cutting are used as side surfaces 23A of the first polarizing films 15A.

[0058] <Second polarizing film formation process> As shown in FIG. 12, in the second polarizing film forming process, a raw material film 41 having the same type, shape, and size as that used in the first polarizing film forming process is used. In FIG. 12, no halftone dots are applied to the raw material film 41 in correspondence with the second polarizing film 15B. The second polarizing film 15B is formed by cutting the raw material film 41 with a laser. The second polarizing film forming process differs from the first polarizing film forming process in that the laser light LB and the raw material film 41 are relatively displaced in a direction along the second side portion 43, and the raw material film 41 is linearly cut in a direction along the second side portion 43. The direction of the relative displacement in the second polarizing film forming process is perpendicular to the direction of the relative displacement in the first polarizing film forming process.

[0059] Then, cutting is performed from one first side portion 42 to the other first side portion 42. By repeating this cutting multiple times, a plurality of second polarizing films 15B in a strip shape that is longer in the direction along the second side portion 43 than in the direction along the first side portion 42 is formed from one sheet of raw material film 41, as shown in Fig. 13. Cut surfaces 46 (see Fig. 14) created by the laser cutting are used as side surfaces 23B of the second polarizing films 15B.

[0060] <Laminate formation process> 15, in the laminate formation step, for example, a film substrate 12 having an adhesive layer 25 (not shown in FIG. 15) formed on a surface 13 to be laminated is used as the film substrate 12. A liquid such as a surfactant or water is applied to the adhesive layer 25.

[0061] A plurality of first polarizing films 15A and a plurality of second polarizing films 15B are attached to the laminated surface 13 in a state where they are arranged alternately in a first direction. For example, as shown in FIG. 16, when a second polarizing film 15B is to be bonded adjacent to a first polarizing film 15A that has already been bonded to the lamination surface 13, the following operations are carried out.

[0062] In first polarizing film 15A, cut surface 46 (see FIG. 14) produced by laser cutting in the first polarizing film formation process serves as side surface 23A. Side surface 23A is inclined with respect to the thickness direction so that the angle θA it forms with surface 21A is an acute angle.

[0063] 16, as indicated by the two-dot chain line, cut surface 46 produced by laser cutting in the second polarizing film forming step is set as side surface 23B. Of both surfaces in the thickness direction of second polarizing film 15B, the surface that forms an acute angle with side surface 23B is set as front surface 21B, and the surface that forms an obtuse angle is set as back surface 22B. Back surface 22B of second polarizing film 15B is opposed to surface 13 to be laminated.

[0064] 16, the second polarizing film 15B is placed on the lamination surface 13 at a predetermined location adjacent to the first polarizing film 15A in the first direction while being positioned thereon. This positioning is performed by sliding the second polarizing film 15B on the liquid.

[0065] The positioned second polarizing film 15B is then bonded to the laminated surface 13 via the adhesive layer 25 and the liquid. As a result of this bonding, a cavity 26 is formed between the side surface 23A of the already bonded first polarizing film 15A, the side surface 23B of the second polarizing film 15B to be bonded, and the laminated surface 13.

[0066] Here, the side surface 23A of the first polarizing film 15A on the second polarizing film 15B side affects the shape of the cavity 26. When the side surface 23A is inclined with respect to the thickness direction so that the angle θA is an acute angle, the shape of the cavity 26 becomes one in which the dimension in the first direction increases toward the laminated surface 13.

[0067] In addition, the side surface 23B of the second polarizing film 15B on the first polarizing film 15A side affects the shape of the cavity 26. When the side surface 23B is inclined with respect to the thickness direction so that the angle θB is an acute angle, the shape of the cavity 26 becomes one in which the dimension in the first direction increases toward the laminated surface 13.

[0068] In this embodiment, both side surfaces 23A and 23B are inclined with respect to the thickness direction so that angles θA and θB are acute angles. Therefore, the cross-sectional shape of cavity 26 is a triangle whose dimension M1 in the first direction (see FIG. 9) increases with increasing distance from front surfaces 21A and 21B to rear surfaces 22A and 22B.

[0069] On the other hand, during the above bonding, foreign matter EM such as air bubbles or dust may get between the back surface 22B and the laminated surface 13. To deal with this, a pressing member PM such as a spatula or roller is moved while being pressed against the second polarizing film 15B. This movement moves the foreign matter EM toward the cavity 26 as shown by the two-dot chain arrow in FIG. 16, while bonding the second polarizing film 15B to the laminated surface 13.

[0070] The cavity 26 is formed at a location adjacent in the first direction to a location where the second polarizing film 15B is attached to the film substrate 12. Therefore, when the foreign matter EM is moved to the cavity 26, it does not remain between the rear surface 22B and the laminated surface 13.

[0071] The cavity 26 extends over the entire length of the polarizing films 15A and 15B in the second direction. Moreover, the cavity 26 is formed between each of the side surfaces 23A of the first polarizing film 15A and the side surfaces 23B of the second polarizing film 15B that are adjacent to each other. The first polarizing film 15A and the second polarizing film 15B each have a longer dimension in the second direction than the dimension in the first direction.

[0072] Therefore, when the second polarizing film 15B is bonded to the laminated surface 13, even if the foreign matter EM is between the back surface 22B and the laminated surface 13 and enters anywhere in the second direction, it is possible to move the foreign matter EM to the cavity portion 26 by simply moving it a short distance.

[0073] Furthermore, as described above, the cavity 26 has a triangular cross-sectional shape. The dimension M1 of the cavity 26 in the first direction is maximum at the layered surface 13. The foreign matter EM is moved along this layered surface 13 and pushed out into the cavity 26. The pushed-out portion is a portion of the cavity 26 where the dimension M1 in the first direction is maximum. Therefore, compared to a case where the dimension M1 of the cavity 26 in the first direction is not maximum at the layered surface 13, the foreign matter EM is more accurately pushed out from between the back surface 22B and the layered surface 13 into the cavity 26.

[0074] The same operations as above are performed when the first polarizing film 15A is bonded adjacent to the second polarizing film 15B that has already been bonded to the laminated surface 13. Even if a foreign matter EM enters between the rear surface 22A and the laminated surface 13 during bonding of the first polarizing film 15A, the foreign matter EM can be moved to the hollow portion 26 by applying pressure to the first polarizing film 15A with the pressing member PM.

[0075] Then, all of the polarizing films 15A, 15B are bonded to the film substrate 12, which is then heated and cooled. This heating causes the liquid to evaporate and hardens the adhesive layer 25. As a result, each of the polarizing films 15A, 15B is bonded to the lamination surface 13 via the adhesive layer 25. A laminate 11 is obtained, which includes the film substrate 12 and the first polarizing film 15A and the second polarizing film 15B each bonded to the lamination surface 13 by adhesion.

[0076] Incidentally, when the foreign matter EM is moved to the cavity 26 by the pressing member PM, or in other words, pushed out into the cavity 26, it can be moved in the second direction along the cavity 26 and discharged to the outside of the cavity 26. Furthermore, if the foreign matter EM is an air bubble, it becomes one with the air in the cavity 26. Furthermore, if the foreign matter EM is a water droplet containing an air bubble, the water droplet is evaporated during the heating.

[0077] Thereafter, as shown in Fig. 17, the excess portion 52 is cut from the laminate 11 and removed in the direction shown by the white arrow in Fig. 17. Then, the remaining portion 53 of the laminate 11 is assembled to the frame 27 as shown in Fig. 3, thereby obtaining the light control film 10 that is entirely flexible as shown in Fig. 2.

[0078] In addition, when manufacturing the light control film 30, the first polarizing film forming step, the second polarizing film forming step, and the laminate forming step are performed in the same manner as in the above-mentioned light control film 10. A low friction layer 32 and a hard coat layer 33 shown in FIG. 7 are formed on the obtained laminate 11 to form a function-added laminate 31. In the same manner as in the case of the above-mentioned laminate 11, the excess portion of the function-added laminate 31 is also cut and removed. Then, the remaining portion of the function-added laminate 31 is assembled to a frame 27 as shown in FIG. 6, and the light control film 30 having flexibility as a whole is obtained as shown in FIG. 2.

[0079] In the obtained light-control films 10 and 30, no foreign matter EM remains between the back surfaces 22A and 22B and the laminated surface 13 (see FIG. 9). Therefore, when the light-control films 10 and 30 are viewed from the outside, the phenomenon in which the foreign matter EM is visible through the polarizing films 15A and 15B is unlikely to occur.

[0080] Moreover, the surface 21A of the first polarizing film 15A and the surface 21B of the second polarizing film 15B that are adjacent to each other are in contact with each other over the entire length in the second direction (see FIG. 9). Therefore, from the outside of the light control films 10 and 30, it is difficult to see a gap between the adjacent surfaces 21A and 21B.

[0081] Furthermore, since the dimension M1 of the cavity 26 in the first direction is 500 μm or less, the cavity 26 is difficult to see. Incidentally, when light is incident on one of the light control films 10 and 30, for example, the light control film 30, from the outside of the light control device A shown in Fig. 1, the light becomes linearly polarized in a direction along the polarization axis of the first polarizing film 15A when it passes through the first polarizing film 15A. In addition, the light incident on the light control film 30 becomes linearly polarized in a direction along the polarization axis of the second polarizing film 15B when it passes through the second polarizing film 15B.

[0082] The degree of light transmission in both light control films 10, 30 is determined by which of the polarizing films 15A, 15B in the light control film 10 overlaps with the polarizing films 15A, 15B in the light control film 30. The combination of the first polarizing film 15A and the second polarizing film 15B that overlap in the thickness direction is changed by sliding the light control film 10 in a first direction, or in other words, by relatively displacing both light control films 10, 30 in the first direction.

[0083] The first polarizing film 15A in the light control film 30 and the first polarizing film 15A in the light control film 10 overlap. Then, the direction in which the polarization axis of the first polarizing film 15A of the former and the direction in which the polarization axis of the first polarizing film 15A of the latter become parallel. At this time, the second polarizing film 15B in the light control film 30 and the second polarizing film 15B in the light control film 10 overlap. The direction in which the polarization axis of the second polarizing film 15B of the former and the direction in which the polarization axis of the second polarizing film 15B of the latter become parallel. Therefore, all of the light that enters the light control film 30 and then passes through the light control film 30 passes through the light control film 10.

[0084] On the other hand, the first polarizing film 15A in the light control film 30 and the second polarizing film 15B in the light control film 10 overlap. Then, the direction in which the polarization axis of the first polarizing film 15A of the former and the direction in which the polarization axis of the second polarizing film 15B of the latter are perpendicular to each other. At this time, the second polarizing film 15B in the light control film 30 and the first polarizing film 15A in the light control film 10 overlap each other. The direction in which the polarization axis of the second polarizing film 15B of the former and the direction in which the polarization axis of the first polarizing film 15A of the latter are perpendicular to each other. Therefore, all of the light that enters the light control film 30 and then transmits through the light control film 30 is blocked (shielded) by the light control film 10.

[0085] Next, the effects of this embodiment will be described. (1) As shown in FIG. 16 , a cavity 26 extending along the entire length of the polarizing films 15A and 15B in the second direction is formed between the side 23A of the first polarizing film 15A, the side 23B of the second polarizing film 15B, and the laminated surface 13.

[0086] Therefore, when the polarizing films 15A, 15B are bonded to the laminated surface 13, even if the foreign matter EM enters anywhere in the second direction, it is possible to move the foreign matter EM to the cavity 26 by simply moving it a short distance. It is possible to prevent the foreign matter EM from remaining between the rear surfaces 22A, 22B and the laminated surface 13. Therefore, it is possible to prevent deterioration in the appearance of the light control films 10, 30 due to the foreign matter EM being visible.

[0087] (2) As shown in Fig. 9, the surface 21A of the first polarizing film 15A and the surface 21B of the adjacent second polarizing film 15B are in contact with each other over their entire length in the second direction. This makes it possible to suppress deterioration in the appearance of the light control films 10 and 30 due to visible gaps between the adjacent surfaces 21A and 21B.

[0088] (3) As shown in Fig. 9, the side surface 23A of the first polarizing film 15A facing the second polarizing film 15B is inclined with respect to the thickness direction so that the angle θA is an acute angle. Therefore, the dimension of the cavity 26 in the first direction increases toward the laminated surface 13 and away from the second polarizing film 15B. Therefore, compared to a case where the dimension is not maximum at the laminated surface 13, it is possible to more accurately push out the foreign matter EM from between the back surface 22A and the laminated surface 13 into the cavity 26.

[0089] (4) As shown in Fig. 9, the side surface 23B of the second polarizing film 15B facing the first polarizing film 15A is inclined with respect to the thickness direction so that the angle θB is an acute angle. Therefore, the dimension of the cavity 26 in the first direction increases toward the laminated surface 13 and away from the first polarizing film 15A. Therefore, compared to a case where the dimension is not maximum at the laminated surface 13, it is possible to more accurately push out the foreign matter EM from between the back surface 22B and the laminated surface 13 into the cavity 26.

[0090] (5) As shown in Fig. 9, the dimension M1 of the cavity 26 in the first direction is set to 500 µm or less. Therefore, the cavity 26 can be prevented from being visually observed from the outside of the light control films 10 and 30.

[0091] (6) As shown in Figures 10, 12, and 14, polarizing films 15A and 15B are formed by laser cutting raw material film 41. Sides 23A and 23B inclined relative to the thickness direction are formed by cut surfaces 46 generated by the laser cutting.

[0092] Therefore, the cutting and the formation of the inclined side surfaces 23A, 23B can be performed simultaneously, or in other words, in one step. Therefore, compared with the case where the formation of the polarizing films 15A, 15B and the formation of the inclined side surfaces 23A, 23B are performed in separate steps, the polarizing films 15A, 15B having the inclined side surfaces 23A, 23B can be formed in fewer and simpler steps.

[0093] (7) In this embodiment, the maximum value of the dimension M1 of the cavity 26 is set to about 20 μm. Therefore, although both ends of the cavity 26 in the second direction are not sealed, foreign matter outside the light control films 10 and 30 is unlikely to enter the cavity 26.

[0094] (8) Since the light control films 10 and 30 are flexible, they can be bent into a curved shape. Therefore, even if the area where the light control device A is applied has a curved surface, the light control films 10 and 30 can be easily curved to follow the curved surface. This effect cannot be obtained or is difficult to obtain when the object to which the polarizing films 15A and 15B are attached is a plate-like object instead of the film substrate 12.

[0095] (9) As shown in Figures 10 and 12, the directions in which raw material film 41 is laser-cut are different by 90° to form two types of polarizing films 15A and 15B whose polarization axes extend in different directions. Therefore, only one type of raw material film 41 is required to form the two types of polarizing films 15A and 15B.

[0096] The above embodiment can also be implemented as modified examples as follows: The above embodiment and the following modified examples can be implemented in combination with each other within a range that does not cause technical contradiction.

[0097] <Matters regarding the structure of the light control films 10 and 30> The low friction layer 32 may be formed on the surfaces 21A and 21B of the polarizing films 15A and 15B in the light control film 10, instead of the light control film 30, as shown by the two-dot chain line in Fig. 4. The low friction layer 32 may also be formed on the surfaces 21A and 21B of the polarizing films 15A and 15B in both light control films 10 and 30.

[0098] The hard coat layer 33 may be provided on the light control film 10 instead of or in addition to the light control film 30. One or both of the low friction layer 32 and the hard coat layer 33 in FIG. 7 may be omitted as appropriate.

[0099] The polarization axis of each second polarizing film 15B may extend in a direction that intersects obliquely (is tilted) with the direction in which the polarization axis of each first polarizing film 15A extends, instead of in a direction that is perpendicular to the direction in which the polarization axis of each first polarizing film 15A extends.

[0100] The polarization axes of the polarizing films 15A and 15B may be formed by metal wires in a wire grid. A wire grid is a structure in which metal wires are arranged in parallel at regular intervals.

[0101] In the first polarizing film 15A shown in FIG. 9, the angle θA that the side 23A makes with respect to the surface 21A, and in the second polarizing film 15B, the angle θB that the side 23B makes with respect to the surface 21B may be the same as in the above embodiment, or may be different.

[0102] 9 and 16, a portion of the side surface 23A of the first polarizing film 15A that is adjacent to the surface 21A may be formed so as not to be inclined with respect to the surface 21A, or in other words, to extend in the thickness direction. Similarly, a portion of the side surface 23B of the second polarizing film 15B that is adjacent to the surface 21B may be formed so as not to be inclined with respect to the surface 21B, or in other words, to extend in the thickness direction.

[0103] Incidentally, extending in the thickness direction means extending parallel to the thickness direction, or in other words, extending in a direction perpendicular to the laminated surface 13 . In this modification, adjacent polarizing films 15A, 15B contact each other not only at their surfaces 21A, 21B but also at portions that are not inclined with respect to the surfaces 21A, 21B, that is, portions that extend in the thickness direction.

[0104] In FIGS. 9 and 16, only one of the side surfaces 23A, 23B of the adjacent polarizing films 15A, 15B may be inclined with respect to the surfaces 21A, 21B, and the other may extend in the thickness direction.

[0105] The cross-sectional shape of the cavity 26 may be changed to a cross-sectional shape different from that of the above embodiment, provided that the surfaces 21A, 21B of the adjacent polarizing films 15A, 15B are in contact with each other. In this case, the cavity 26 is located at a certain distance or more from the surfaces 21A, 21B toward the film substrate 12.

[0106] For example, the dimension of the cavity 26 in the first direction may be constant in the thickness direction. In this case, the cross-sectional shape of the cavity 26 is a rectangle. The size of the cavity 26, particularly the cross-sectional size, may be changed, provided that the dimension M1 is 500 μm or less.

[0107] Depending on the environment in which the light control device A is used, both ends of the cavity 26 in the second direction may be sealed by filling the both ends with a sealant, etc. In this way, the performance of preventing foreign matter from entering the cavity 26 from the outside of the light control films 10 and 30 is improved.

[0108] This modification is also effective when the cross-sectional shape of the cavity 26 is enlarged as described above. The side surfaces 23A, 23B located at both ends in the first direction may or may not be inclined with respect to the thickness direction.

[0109] <Matters regarding the manufacture of light control films 10 and 30> The side surfaces 23A and 23B that are inclined with respect to the thickness direction may be formed by a method other than laser cutting.

[0110] In the laminate formation step, for example, instead of or in addition to the laminated surface 13 of the film substrate 12, the polarizing films 15A and 15B may have adhesive layers 25 formed on their rear surfaces 22A and 22B.

[0111] In the laminate forming step, as shown in FIG. 18, a raw material film 55 in which the raw material of the film substrate 12 is wound in a roll shape may be used. The raw material film 55 can be considered as a plurality of film substrates 12 arranged in a row and connected. In this case, the raw material film 55 is pulled out, and one surface thereof is made the surface to be laminated 13. As in the above embodiment, the first polarizing film 15A and the second polarizing film 15B may be laminated to the surface to be laminated 13 in a state where they are alternately arranged in the first direction. Then, the raw material film 55 in which the polarizing films 15A and 15B are laminated may be heated and cooled, and then, as shown in FIG. 19, fed in the direction indicated by the outlined arrow by a pair of rollers 56. The fed material is cut at regular intervals to obtain the desired laminate 11.

[0112] <Matters regarding dimming device A> The relative displacement of the pair of light control films 10, 30 in the first direction may be achieved by sliding at least one of the light control films 10, 30 in the first direction. Therefore, as in the above embodiment, only the light control film 10 may be subject to sliding, or only the light control film 30 may be subject to sliding. Also, both light control films 10, 30 may be subject to sliding. [Explanation of symbols]

[0113] 10,30...Light-adjusting film (light-adjusting element) 11...Laminate 12...Film substrate 13…Surface to be laminated 15A…First polarizing film 15B…Second polarizing film 21A, 21B…Surface 22A, 22B…Back side 23A, 23B…Side 26...Cavity part 46...Cut surface θA, θB…Angle A…Dimmer device M1…Dimensions

Claims

1. A light control device includes a pair of light control elements arranged opposite to each other in a thickness direction, and the light control elements are relatively displaced in a first direction perpendicular to the thickness direction to adjust the amount of light transmitted through the light control elements. The light control film is used as the light control elements, The polarizing film has a laminate in which two types of polarizing films are laminated on a film substrate, the film substrate has one surface in the thickness direction as a surface to be laminated, and each polarizing film has one surface in the thickness direction as a front surface and the other surface as a back surface, and has side surfaces on both sides in the first direction; The two types of polarizing films have a rectangular shape whose dimension in a second direction perpendicular to both the thickness direction and the first direction is longer than the dimension in the first direction, and have polarization axes extending in directions different from each other, In the laminate, the two types of polarizing films are arranged alternately in the first direction and are bonded to the laminated surface at the back surface, In the adjacent polarizing films, a cavity is formed between the pair of adjacent side surfaces and the laminated surface, the cavity extending over the entire length of the polarizing film in the second direction, A light management film, wherein the surfaces of adjacent polarizing films are in contact with each other.

2. The light control film according to claim 1 , wherein the side surface of each polarizing film that faces an adjacent polarizing film is inclined with respect to the thickness direction so that the angle the side surface forms with respect to the surface is an acute angle.

3. The light control film according to claim 1 , wherein the cavity is formed so that the dimension in the first direction is 500 μm or less.

4. The light-controlling film according to any one of claims 1 to 3, wherein each polarizing film is formed by laser cutting, and the side surface inclined with respect to the thickness direction is formed by a cut surface resulting from the laser cutting.

Images