Structure, structure module, and structure manufacturing method

Abstract

To provide a structure which can be easily replaced relative to a sensor device while easily imparting a water-repellent function to the sensor device and maintaining optical characteristics of the sensor device.SOLUTION: A structure 100 attached on a curved outer surface of a sensor device 400 includes: a substrate 101; and a fine rugged structure layer provided on both surfaces of the substrate 101. The fine rugged structure layer includes: a first fine rugged structure layer 102 positioned on the side of the sensor device 400; and a second fine rugged structure layer 103 positioned on the opposite side to the sensor device 400. The second fine rugged structure layer 103 has water repellency. The structure 100 has a three-dimensional shape following the curved shape of the outer surface.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a structure, a structure module, and a method for manufacturing a structure.

Background Art

[0002] In-vehicle camera modules used for in-vehicle back monitors or out-of-vehicle sensing applications, or sensor devices used outdoors such as camera modules for surveillance cameras are known. The exterior lens of the sensor used in such a sensor device usually has a three-dimensional shape in order to realize a light condensing function. Further, in order to avoid deterioration of visibility or image quality (occurrence of color unevenness, ghost, etc.) due to reflection of external light, an antireflection treatment is often performed on the light incident surface of a substrate such as a lens. As the antireflection treatment, methods of reducing the reflectance by providing a multilayer antireflection film on the light incident surface or by forming a fine uneven structure are known.

[0003] Furthermore, since the above lens is exposed to an external environment containing dust or water droplets due to use outdoors, high durability is required. In order to protect the lens from dust or water droplets contained in the external environment, a method of applying a water repellent coating to the outermost surface of the lens is known.

[0004] For example, Patent Document 1 discloses a method of further applying a water repellent coating to the surface of a lens having an antireflection coating. However, when a water repellent coating is applied to a microscopically flat surface, there is a problem that the contact angle is as small as about 100 degrees and the water repellency is insufficient. Although a superhydrophobic state can be achieved by coating a nanoporous film, the water repellent coating is removed when exposed to UV (Ultra-Violet) light or a kill resistance test, and the water repellency is impaired.

[0005] In Patent Document 2, a technique for reducing reflection by directly forming an uneven structure having a wavelength equal to or less than that of light detected by a sensor device on the lens surface is disclosed. Thereby, the reflectance of the lens surface having a curved surface shape is reduced. In addition, Patent Document 2 also discloses that water repellency is achieved by adding a water-repellent material to the lens-forming material. Thereby, it is said that water droplet adhesion or dust adhesion is suppressed. However, in this method, once the water repellency is lost due to the external environment, it is difficult to restore the performance of the lens.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] In the above-described conventional technology, sufficient consideration has not been given to providing a structure that can be easily replaced by being attached to a sensor device as a separate component while easily imparting a water-repellent function and maintaining the optical characteristics of the sensor device.

[0008] An object of the present invention is to provide a structure that can be easily replaced with respect to a sensor device, a structure module formed by attaching the structure to the sensor device, and a method for manufacturing the structure while easily imparting a water-repellent function and maintaining the optical characteristics of the sensor device.

Means for Solving the Problems

[0009] That is, the gist configuration of the present invention is as follows. (1) A structure attached to the outer surface of a sensor device having a curved surface shape, comprising a substrate and fine uneven structure layers disposed on both surfaces of the substrate, wherein the fine uneven structure layers include a first fine uneven structure layer located on the sensor device side and a second fine uneven structure layer located on the side opposite to the sensor device side, the second fine uneven structure layer has water repellency, and the structure has a three-dimensional shape following the curved surface shape of the outer surface.

[0010] (2) The structure according to (1) above, wherein the first fine uneven structure layer has a pitch equal to or less than the wavelength of light detected by the sensor device.

[0011] (3) The structure according to (1) or (2) above, which is configured to be detachable from the outer surface.

[0012] (4) The structure according to any one of (1) to (3) above, wherein the substrate has thermoplasticity.

[0013] (5) The structure according to any one of (1) to (4) above, having a total light transmittance of 98% or more.

[0014] (6) The structure according to any one of (1) to (5) above, wherein the water droplet contact angle of the second fine uneven structure layer is 130 degrees or more.

[0015] (7) A structure module comprising the sensor device and the structure according to any one of (1) to (6) attached to the outer surface of the sensor device.

[0016] (8) The structure module according to (7) above, wherein the radius of curvature of the outer surface is 5 mm or more and 500 mm or less.

[0017] (9) The structure module according to (7) or (8) above, wherein the sensor device includes an in-vehicle camera module.

[0018] The sensor device is the structural module according to any one of (7) to (9) above, including a camera module for a surveillance camera.

[0019] A method for manufacturing a structure according to any one of (1) to (6) above, comprising: a substrate and a first holding film having a fine concavo-convex structure on its surface, sandwiching a first UV curable resin such that the fine concavo-convex structure of the first holding film contacts the first UV curable resin, and performing a first pressing step of pressing; curing the sandwiched first UV curable resin by irradiation with UV light to form a first fine concavo-convex structure layer on one surface of the substrate, a first curing step; peeling the first holding film from the first fine concavo-convex structure layer, a first peeling step; a substrate and a second holding film having a fine concavo-convex structure on its surface, sandwiching a second UV curable resin such that the other surface of the substrate and the fine concavo-convex structure of the second holding film contact the second UV curable resin, and performing a second pressing step of pressing; curing the sandwiched second UV curable resin by irradiation with UV light to form a second fine concavo-convex structure layer on the other surface of the substrate, a second curing step; peeling the second holding film from the second fine concavo-convex structure layer, a second peeling step; and performing a vacuum heat treatment on the substrate having fine concavo-convex structures formed on both surfaces to form a three-dimensional shape that follows the curved surface shape of the outer surface of the sensor device to be attached, a forming step. A method for manufacturing a structure.

Advantages of the Invention

[0020] According to the present invention, it is possible to provide a structure that can be easily exchanged for a sensor device while easily imparting a water repellent function and maintaining the optical characteristics of the sensor device, a structural module formed by attaching the structure to the sensor device, and a method for manufacturing the structure.

Brief Description of the Drawings

[0021]

Figure 1

Figure 2A

Figure 2B

Figure 2C

Figure 2D

Figure 2E

Figure 2F

Figure 2G

Figure 2H

Figure 2I

Figure 3

Embodiments for Carrying Out the Invention

[0022] Hereinafter, a structure according to an embodiment of the present invention (hereinafter, may be referred to as "the structure of the present embodiment") will be described.

[0023] (Structure) As shown in FIG. 1, the structure 100 of the present embodiment has a substrate 101 and fine concavo-convex structure layers disposed on both surfaces of the substrate 101. The fine concavo-convex structure layers include a first fine concavo-convex structure layer 102 and a second fine concavo-convex structure layer 103. The first fine concavo-convex structure layer 102 is located on the sensor device side described later. The second fine concavo-convex structure layer 103 is located on the side opposite to the sensor device side. The second fine concavo-convex structure layer 103 has water repellency. In this specification, "water repellency" refers to, for example, a water droplet contact angle of 130 degrees or more. The structure 100 is further characterized by having a three-dimensional shape that follows the curved surface shape of the outer surface of the sensor device.

[0024] In this specification, the water droplet contact angle was measured by the θ / 2 method based on JIS R3257 "Test Method for Wettability of Substrate Glass Surfaces". Specifically, the angle formed by the boundary line between the water droplet and the water droplet contact object, and the straight line connecting one of the contact points between the water droplet and the water droplet contact object and the apex of the water droplet was measured by an optical reading device, and the obtained value was doubled.

[0025] In this specification, the "three-dimensional shape that follows the curved surface shape of the outer surface" includes, for example, a three-dimensional shape that is the same as or corresponds to the curved surface shape of the outer surface of the sensor device. For example, the "three-dimensional shape that follows the curved surface shape of the outer surface" includes a three-dimensional shape having a radius of curvature that is the same as or approximate to the radius of curvature of the outer surface of the sensor device. "Approximate to the radius of curvature of the outer surface of the sensor device" means, for example, including an error of preferably 10% or less, more preferably 5% or less, and even more preferably 1% or less with respect to the radius of curvature of the outer surface.

[0026] In this specification, the wavelength of the light detected by the sensor device is in the visible light band (approximately 360 nm to 830 nm), and the total light transmittance means the light transmittance in this band.

[0027] In this specification, "transparent" means that the transmittance of light having a wavelength belonging to the visible light band (approximately 360 nm to 830 nm) is high, for example, the transmittance of the light is 70% or more.

[0028] <Substrate> The substrate 101 used in this embodiment preferably typically has thermoplasticity. The configuration of the substrate 101 used in this embodiment is not particularly limited and can be appropriately selected according to the purpose. For example, a polycarbonate film or the like can be mentioned. The substrate 101 is preferably transparent, and the thickness is preferably 30 μm or more and 200 μm or less. Also, the surface of the substrate 101 may be coated.

[0029] <First fine concavo-convex structure layer> In the first fine concavo-convex structure layer 102 used in this embodiment, a fine concavo-convex pattern (a convex portion that is convex in the thickness direction of the fine concavo-convex structure and a concave portion that is concave in the thickness direction of the fine concavo-convex structure) is formed. Thereby, the antireflection performance can be improved. The convex portions and the concave portions may be arranged periodically (for example, in a staggered grid pattern or a rectangular grid pattern), or may be arranged randomly. Also, the shapes of the convex portions and the concave portions are not particularly limited and may be bullet-shaped, cone-shaped, columnar, or needle-shaped, etc. Note that the shape of the concave portion means the shape formed by the inner wall of the concave portion.

[0030] The average period (pitch) of the concavo-convex pattern of the first fine concavo-convex structure layer 102 is preferably equal to or less than the wavelength of the light detected by the sensor device to be used, more preferably equal to or less than the visible light wavelength (for example, 830 nm or less), still more preferably 350 nm or less, most preferably 280 nm or less, and also more preferably 100 nm or more, still more preferably 150 nm or more. By making the pitch of the concavo-convex pattern of the first fine concavo-convex structure layer 102 equal to or less than the visible light wavelength, that is, a so-called moth-eye structure, a further improvement in antireflection performance can be achieved.

[0031] Here, the average period of the concavo-convex pattern is the arithmetic mean of the distances between adjacent convex portions and between adjacent concave portions. The concavo-convex pattern can be observed, for example, by a scanning electron microscope (SEM) or a cross-sectional transmission electron microscope (cross-sectional TEM). As a method for calculating the average period, for example, several combinations of adjacent convex portions and several combinations of adjacent concave portions are picked up, the distances between the convex portions and the distances between the concave portions constituting each combination are measured, and the measured values are averaged.

[0032] Also, the depth (height of the convex portion) of the concave portion in the concavo-convex pattern of the first fine concavo-convex structure layer 102 is not particularly limited, but is preferably 150 nm or more, more preferably 190 nm or more, and is preferably 300 nm or less, more preferably 230 nm or less. On the other hand, the thickness of the portion where the concavo-convex pattern is not formed in the first fine concavo-convex structure layer 102, that is, the base portion 1021 (see FIG. 2D), is preferably 250 nm or less. If the thickness of the portion that is not the fine concavo-convex structure of the first fine concavo-convex structure layer 102 is 250 nm or less, the vibration (ripple) of the reflection spectrum due to multiple reflections between the substrate 101 and the first fine concavo-convex structure layer 102 becomes smaller, and color unevenness or reflection deterioration can be further suppressed. From the same viewpoint, the thickness of the portion that is not the fine concavo-convex structure of the first fine concavo-convex structure layer 102 is more preferably 200 nm or less, further preferably 100 nm or less, and particularly preferably 50 nm or less. On the other hand, from the viewpoint of practicality, the thickness of the portion that is not the fine concavo-convex structure of the first fine concavo-convex structure layer 102 can be 0.01 nm or more. Note that the thickness of the portion that is not the fine concavo-convex structure in the first fine concavo-convex structure layer 102 refers to the distance in the stacking direction or the film thickness direction between the surface where the fine concavo-convex structure is not formed and the apex of the deepest concave portion of the formed fine concavo-convex structure.

[0033] The first fine concavo-convex structure layer 102 used in this embodiment is preferably made of, for example, a UV curable resin. The UV curable resin is not particularly limited, and examples thereof include a UV curable acrylic resin and a UV curable epoxy resin.

[0034] <Second fine concavo-convex structure layer> The second fine concavo-convex structure layer 103 used in this embodiment has water repellency. That is, the water droplet contact angle of the second fine concavo-convex structure layer 103 is, for example, 130 degrees or more, preferably 140 degrees or more, more preferably 145 degrees or more, and even more preferably 150 degrees or more.

[0035] Similar to the above-described first fine concavo-convex structure layer 102, a fine concavo-convex pattern (a convex portion that is convex in the thickness direction of the fine concavo-convex structure and a concave portion that is concave in the thickness direction of the fine concavo-convex structure) is formed in the second fine concavo-convex structure layer 103. Thereby, the antireflection performance can be improved. The convex portions and the concave portions may be arranged periodically (for example, in a staggered lattice pattern or a rectangular lattice pattern), or may be arranged randomly. Further, the shapes of the convex portions and the concave portions are not particularly limited, and may be bullet-shaped, cone-shaped, columnar, needle-shaped, or the like.

[0036] The average period (pitch) of the concavo-convex pattern of the second fine concavo-convex structure layer 103 is preferably equal to or less than the visible light wavelength (for example, 830 nm or less), more preferably 350 nm or less, even more preferably 280 nm or less, and also more preferably 100 nm or more, even more preferably 150 nm or more. By making the pitch of the concavo-convex pattern of the second fine concavo-convex structure layer 103 equal to or less than the visible light wavelength, that is, a so-called moth-eye structure, further improvement in antireflection performance can be achieved.

[0037] Further, the depth of the concave portion (height of the convex portion) in the uneven pattern of the second fine uneven structure layer 103 is not particularly limited, but is preferably 150 nm or more, more preferably 190 nm or more, and is preferably 400 nm or less, more preferably 300 nm or less, and even more preferably 230 nm or less. On the other hand, the thickness of the portion where the uneven pattern is not formed in the second fine uneven structure layer 103, that is, the base portion 1031 (FIG. 2H), is preferably 250 nm or less. If the thickness of the portion that is not the fine uneven structure of the second fine uneven structure layer 103 is 250 nm or less, the vibration (ripple) of the reflection spectrum due to multiple reflections between the substrate 101 and the second fine uneven structure layer 103 becomes smaller, and color unevenness or reflection deterioration can be further suppressed. From the same viewpoint, the thickness of the portion that is not the fine uneven structure of the second fine uneven structure layer 103 is more preferably 200 nm or less, even more preferably 100 nm or less, and particularly preferably 50 nm or less. On the other hand, the thickness of the portion that is not the fine uneven structure of the second fine uneven structure layer 103 can be 0.01 nm or more from the viewpoint of practicality. Note that the thickness of the portion that is not the fine uneven structure in the second fine uneven structure layer 103 refers to the distance in the stacking direction or film thickness direction between the surface where the fine uneven structure is not formed and the apex of the deepest concave portion of the formed fine uneven structure.

[0038] Note that the arrangement modes of the concave and convex portions, the average period of the uneven pattern, the depth of the concave portion, etc. of the respective fine uneven structure portions of the first fine uneven structure layer 102 and the second fine uneven structure layer 103 may be the same as or different from each other.

[0039] The second fine uneven structure layer 103 used in this embodiment is preferably made of, for example, a UV curable resin. The UV curable resin is not particularly limited, and examples thereof include a UV curable acrylic resin and a UV curable epoxy resin.

[0040] In this embodiment, when the refractive indices of the substrate 101, the first fine concavo-convex structure layer 102, and the second fine concavo-convex structure layer 103 are n0, n1, and n2, respectively, it is preferable that the absolute value of the refractive index difference between n0 and n1 is within 0.2 and the absolute value of the refractive index difference between n0 and n2 is within 0.2. By satisfying this condition, the vibration (ripple) of the reflection spectrum caused by multiple reflections between layers becomes small, color unevenness or reflection deterioration is suppressed, and a structure with high transmittance can be obtained.

[0041] The total light transmittance of the structure 100 is preferably 98% or more, more preferably 99% or more, and even more preferably 99.5% or more. Further, the structure 100 has a three-dimensional shape that follows the curved surface shape of the outer surface of the sensor device.

[0042] (Method for manufacturing the structure) The method for manufacturing the structure of the present invention is characterized by including a first pressing step, a first curing step, a first peeling step, a second pressing step, a second curing step, a second peeling step, and a forming step. According to this method, fine concavo-convex structure layers are arranged on both sides of the substrate, and a water-repellent structure that can be attached to and detached from the target sensor device can be manufactured.

[0043] Hereinafter, a method for manufacturing a structure according to an embodiment of the present invention (hereinafter sometimes referred to as "the manufacturing method of the present embodiment") will be described with reference to FIGS. 2A to 2H.

[0044] <First pressing step> In the first pressing step, a first A step of sandwiching the UV curable resin such that the fine concavo-convex structure of the first holding film contacts the first UV curable resin and performing pressure bonding. Specifically, in the first pressure bonding step of the manufacturing method of the present embodiment, as shown in FIG. 2A, first, the first UV curable resin 151 is sandwiched between the substrate 101 and the first holding film 201 having a fine concavo-convex structure on the surface such that the fine concavo-convex structure of the first holding film 201 contacts the first UV curable resin 151. Thereby, a first sandwiching body is obtained. The first UV curable resin 151 is not particularly limited, and examples thereof include UV curable acrylic resins and UV curable epoxy resins. Further, various additives such as a curing initiator may be added to the first UV curable resin 151 as necessary.

[0045] The first UV curable resin 151 preferably has a viscosity of 1000 cps or less. If the viscosity of the first UV curable resin 151 is 1000 cps or less, the film thickness becomes thin, curling due to shrinkage during curing is suppressed, and thermoplastic deformation becomes good.

[0046] Here, the first holding film 201 having a fine concavo-convex structure on the surface can be produced, for example, by forming a fine concavo-convex layer having a predetermined concavo-convex pattern on a base substrate.

[0047] The material constituting the base substrate is not particularly limited, but preferably it is transparent and difficult to break, and examples thereof include PET (polyethylene terephthalate), TAC (triacetyl cellulose), PC (polycarbonate), etc. Further, the formation of the fine uneven layer on the base substrate can be achieved, for example, by a process of applying an uncured UV curable resin on one surface of the base substrate, a process of bringing a roll having a corresponding uneven pattern formed thereon into close contact with the applied UV curable resin to transfer the uneven pattern to the UV curable resin, a process of irradiating the applied UV curable resin with UV light to cure it, and a process of peeling the cured UV curable resin from the roll. Note that the UV curable resin is not particularly limited, and examples thereof include UV curable acrylic resins, UV curable epoxy resins, etc. Further, various additives such as a curing initiator may be added to the UV curable resin as necessary.

[0048] The first holding film 201 may be coated with a film made of an inorganic material on the surface of the fine uneven structure in order to enhance the peelability.

[0049] Next, as shown in FIG. 2A, the first sandwiching body is pressure-bonded in the sandwiching direction by a pressure-bonding device such as a roll laminator 160. Here, in the first pressure-bonding step, the thickness of the finally obtained first fine uneven structure layer 102 can be adjusted by adjusting the pressure during pressure-bonding.

[0050] <First curing step> The first curing step is a step of curing the sandwiched first UV curable resin by irradiation with UV light to form a first fine concavo-convex structure layer on one surface of the substrate. Specifically, in the first curing step of the manufacturing method of the present embodiment, as shown in FIG. 2B, the first UV curable resin 151 sandwiched in the first pressing step is irradiated with UV light to cure the first UV curable resin 151. By curing the first UV curable resin 151, a first intermediate structure 250 having a first fine concavo-convex structure layer 102 formed on one surface of the substrate 101 as shown in FIG. 2C is obtained. Note that the first curing step may be performed at the same timing as the first pressing step. The fine concavo-convex structure on the surface of the thus obtained first fine concavo-convex structure layer 102 can be engaged with the fine concavo-convex structure of the first holding film 201 without a gap.

[0051] <First peeling step> The first peeling step is a step of peeling the first holding film from the first fine concavo-convex structure layer. The first peeling step can be performed after the first curing step. Specifically, in the first peeling step of the manufacturing method of the present embodiment, the first holding film 201 existing on the first intermediate structure 250 shown in FIG. 2C is peeled to obtain the state shown in FIG. 2D.

[0052] <Second pressing step> In the second pressing step, a second UV curable resin is sandwiched and pressed between the substrate and a second holding film having a fine concavo-convex structure on its surface such that the fine concavo-convex structure of the second holding film contacts the second UV curable resin. The second pressing step can be performed after the first peeling step. Specifically, in the second pressing step of the manufacturing method of the present embodiment, as shown in FIG. 2E, a second UV curable resin 152 is sandwiched between the other surface of the substrate 101, that is, the surface of the substrate 101 opposite to the first fine concavo-convex structure layer 102, and a second holding film 202 having a fine concavo-convex structure on its surface such that the fine concavo-convex structure of the second holding film 202 contacts the second UV curable resin 152. Thereby, a second sandwiching body is obtained. The second UV curable resin 152 is not particularly limited, and examples thereof include a UV curable acrylic resin and a UV curable epoxy resin. It is preferable to add an additive that exhibits water repellency to the second UV curable resin 152. This makes it possible for the second fine concavo-convex structure layer 103 formed later to have water repellency. Further, various additives such as a curing initiator may be added to the second UV curable resin 152 as necessary.

[0053] Here, examples of the additive that exhibits water repellency include a fluororesin and a silicone resin. Further, the addition amount of the additive to the second UV curable resin is preferably, for example, 0.01% by mass or more and 5% by mass or less, more preferably 0.1% by mass or more and 2% by mass or less, based on the second UV curable resin 152.

[0054] The second UV curable resin 152 preferably has a viscosity of 1000 cps or less. If the viscosity of the second UV curable resin 152 is 1000 cps or less, the film thickness becomes thin, curl due to shrinkage during curing is suppressed, and thermoplastic deformation is good.

[0055] Here, the second holding film 202 can be produced in the same manner as the first holding film 201, for example, by forming a fine concavo-convex layer having a predetermined concavo-convex pattern on a base substrate.

[0056] In order to enhance the releasability, the second holding film 202 may be coated with a film made of an inorganic material on the surface having the fine concavo-convex structure.

[0057] Next, as shown in FIG. 2E, the second sandwiching body is pressure-bonded in the sandwiching direction by a pressure-bonding device such as a roll laminator 160. Here, in the second pressure-bonding step, by adjusting the pressure during pressure-bonding, the thickness of the finally obtained second fine concavo-convex structure layer 103 can be adjusted.

[0058] <Second curing step> The second curing step is a step of curing the sandwiched second UV curable resin by irradiating with UV light to form a second fine concavo-convex structure layer on the other surface of the substrate. The operation of the second curing step is substantially the same as that of the first curing step. Specifically, in the second curing step in the manufacturing method of the present embodiment, as shown in FIG. 2F, UV light is irradiated on the second UV curable resin 152 sandwiched in the second pressure-bonding step to cure the second UV curable resin 152. By curing the second UV curable resin 152, a second intermediate structure 260 in which a second fine concavo-convex structure layer 103 is formed on the other surface (the surface of the first intermediate structure 250) of the substrate 101 as shown in FIG. 2G is obtained. Note that the second curing step may be performed at the same timing as the second pressure-bonding step. The fine concavo-convex structure on the surface of the second fine concavo-convex structure layer 103 thus obtained can be engaged with the fine concavo-convex structure of the second holding film 202 without a gap.

[0059] <Second peeling step> The second peeling step is a step of peeling the second holding film from the second fine concavo-convex structure layer. The second peeling step can be performed after the second curing step. The operation of the second peeling step is substantially the same as that of the first peeling step. Specifically, in the second peeling step in the manufacturing method of the present embodiment, the second holding film 202 existing on the second intermediate structure 260 is peeled to obtain the state shown in FIG. 2H.

[0060] <Forming step> The shaping process is a process of shaping the substrate with fine uneven structures formed on both sides into a three-dimensional shape that follows the curved surface shape of the outer surface of the sensor device to be attached by performing a vacuum heat treatment. In the shaping process in the manufacturing method of the present embodiment, first, a lens having a curvature close to that of the outer surface is prepared. Next, as shown in FIG. 2I, the second intermediate structure 260 after the second peeling process is placed on the prepared lens, and a vacuum heat treatment is performed. The method of the vacuum heat treatment is not particularly limited, and examples thereof include a method using a heating dryer in a vacuum chamber. Thus, a structure 100 having a three-dimensional shape that follows the curved surface shape of the outer surface is obtained. By using such a structure having a three-dimensional shape, the structure 100 can be attached to the sensor device in a spatially stable state without impairing the functions of the sensor device to be used and the optical characteristics of the structure.

[0061] (Structural body module) As shown in FIG. 3, the structural body module 500 of the present embodiment includes a sensor device 400 and a structure 100 attached to the outer surface of the sensor device 400. The sensor device 400 has a lens 401 located outermost in the sensor device 400. The outer surface of the sensor device 400, that is, the outer surface of the lens 401, has a curved surface shape. The radius of curvature of the outer surface is preferably 3 mm or more and 1000 mm or less, and more preferably 5 mm or more and 500 mm or less. The structure 100 is preferably configured to be detachable from the outer surface. Examples of the method of attaching the structure 100 to the outer surface include a method of installing it with screws, physical clamps, adhesives, or the like.

[0062] <Use of the structural body module> In the structural body module 500 of the present embodiment, the sensor device 400 may include an in-vehicle camera module or a camera module for a surveillance camera. That is, the structural body module 500 may be, for example, an in-vehicle camera module or a camera module for a surveillance camera to which the structure 100 is attached.

Example

[0063] Next, the present invention will be described more specifically using examples and comparative examples, but the present invention is not limited to the following examples.

[0064] (Example 1) A structure 100 having a substrate 101, with a first fine concavo-convex structure layer 102 and a second fine concavo-convex structure layer 103 formed on both surfaces of the substrate 101 respectively, and having a three-dimensional shape that follows the curved surface shape of the outer surface of the sensor device 400, was used as the object of the model for the structure module 500 attached to the lens 401 of the sensor device 400. Here, for the manufacture of the structure 100, a polycarbonate film with a thickness of 150 μm was used as the substrate 101. The first fine concavo-convex structure layer 102 was formed using a UV acrylic resin, and the fine concavo-convex structure was a moth-eye structure with a pitch of 200 nm and a depth of the concave portion (height of the convex portion) of 200 nm. The second fine concavo-convex structure layer 103 was formed using a resin mixture in which about 2% by mass of a fluororesin was added to the UV acrylic resin, and the fine concavo-convex structure was a moth-eye structure with a pitch of 200 nm and a depth of the concave portion (height of the convex portion) of 200 nm. Here, the thickness of the base portion 1021 (portion where no fine concavo-convex structure is formed) of the first fine concavo-convex structure layer 102 was 3000 nm. The thickness of the base portion 1031 of the second fine concavo-convex structure layer 103 was 3000 nm. Also, the refractive index n0 of the substrate 101 was 1.6. The refractive index n1 of the first fine concavo-convex structure layer 102 was 1.52. The refractive index n2 of the second fine concavo-convex structure layer 103 was 1.52.

[0065] Specifically, according to the manufacturing method of the present invention, a first fine concavo-convex structure layer 102 and a second fine concavo-convex structure layer 103 were respectively formed on both sides of the substrate 101 to produce a second intermediate structure 260. Then, according to the manufacturing method of the present invention, a molding lens 300 having a curvature close to the outer surface of the sensor device 400 to which the finally obtained structure 100 is attached was prepared. The second intermediate structure 260 was placed on the molding lens 300 such that the first fine concavo-convex structure layer 102 was on the lens side, and a vacuum heat treatment was performed to mold it into a three-dimensional shape following the curved surface shape of the molding lens 300, obtaining the structure 100. Here, the vacuum heat treatment was performed using a heating dryer in a vacuum chamber. The total light transmittance of the light from the second fine concavo-convex structure layer 103 side of the structure 100 obtained by molding was 99%. Further, the obtained structure 100 was attached with an adhesive tape to the outer edge of the lens non-effective area of the outer surface of the camera module to form a structure module 500. At this time, the curvature of the outer surface of the camera module used was about 15 mm level.

[0066] Next, the water droplet contact angle of the outer surface of the structure 100 (the surface of the second fine concavo-convex structure layer 103), the water droplet adhesion test when the sample (structure module 500) was installed at an inclination of 45 degrees, and the water droplet adhesion test when the sample was installed almost horizontally were conducted. In the water droplet adhesion test, pure water was dropped onto the second fine concavo-convex structure layer 103 of the sample with a dropper, and it was confirmed whether the dropped water droplet flowed after touching the sample, and the evaluation was based on the following evaluation criteria. Also, after these tests, the attached structure 100 was detached from the camera module, and it was confirmed whether it could be attached again, and the interchangeability was evaluated based on the following evaluation criteria. The above results are shown in Table 1.

[0067] The evaluation criteria for the water droplet adhesion test in Table 1 are as follows. A: The water droplet bounces off and does not adhere to the sample. B: Immediately after the start of the test, the water droplet bounces off, but it starts to adhere after about 60 seconds. C: The water droplet adheres to the surface.

[0068] The evaluation criteria for the interchangeability in Table 1 are as follows. A: It is possible to exchange and restore functions. C: It is impossible to exchange and restore functions.

[0069] (Example 2) A structural body module 500 similar to that of Example 1 was used as a model, except that the fine concavo-convex structure of the second fine concavo-convex structure layer 103 had a moth-eye structure with a depth of the concave portion (height of the convex portion) of 400 nm, and a UV acrylic resin with about 2% fluororesin was used. The total light transmittance of the light from the second fine concavo-convex structure layer 103 side of the formed structural body 100 was 99%. In the same manner as in Example 1, the water droplet contact angle, water droplet adhesion test, and exchangeability test were conducted. The results are shown in Table 1.

[0070] (Comparative Example 1) A model of a structural body module in which a multilayer film made of a dielectric was directly formed on a lens having a curved surface shape was used as a target. Here, the surface of the multilayer film was smooth, and the total film thickness of the multilayer film was about 0.2 μm. In the same manner as in Example 1, the water droplet contact angle and water droplet adhesion test were conducted. Since the evaluation of exchangeability was for directly forming the multilayer film, it was evaluated whether it could be reformed after removal with a reticle or the like. The results are shown in Table 1.

[0071] (Comparative Example 2) A model of a structural body module in which a fluorine coating was directly applied to a lens having a curved surface shape was used as a target. Here, the film thickness of the fluorine coating film was estimated to be 20 nm. In the same manner as in Example 1, the water droplet contact angle and water droplet adhesion test were conducted, and in the same manner as in Comparative Example 1, the exchangeability test was conducted. The results are shown in Table 1.

[0072] (Comparative Example 3) A model of a structural module in which a moth-eye structure was directly formed on a lens having a curved surface was targeted. The lens was subjected to a silane coupling treatment, and a fine concavo-convex structure was formed on the surface of the lens using a UV acrylic resin. The fine concavo-convex structure exists only on the surface of the structural module, and the surface of the UV acrylic resin in contact with the lens is smooth. Here, the pitch of the moth-eye structure is 200 nm, and the depth of the concave portion (height of the convex portion) is 200 nm. In the same manner as in Example 1, a water droplet contact angle and a water droplet adhesion test were conducted, and in the same manner as in Comparative Example 1, a replaceability test was conducted. The results are shown in Table 1.

[0073] (Comparative Example 4) A model of a structural module similar to that of Comparative Example 3 was targeted, except that the UV acrylic resin used for forming the moth-eye structure was a fluorine-containing UV acrylic resin. In the same manner as in Example 1, a water droplet contact angle and a water droplet adhesion test were conducted, and in the same manner as in Comparative Example 1, a replaceability test was conducted. The results are shown in Table 1.

[0074]

Table 1

[0075] From Table 1, it can be seen that the structural modules 500 according to Example 1 and Example 2 have a water droplet contact angle of 130 degrees or more, have replaceability, and a total light transmittance of 98% or more. Also, in the water droplet adhesion test when the sample (structural module 500) was installed at an inclination of 45 degrees, it can be seen that no water droplets adhered in both Example 1 and Example 2. In the water droplet adhesion test when the sample was installed horizontally, in Example 1, water droplets began to adhere about 60 seconds after the water droplets were dropped, while in Example 2, it can be seen that no water droplets adhered. From the above, Example 2 may be a structural body 100 detachable from the sensor device 400 having high transmittance and water repellency. On the other hand, it can be seen that Example 1 is a structural body 100 detachable from the sensor device 400, which is inferior to Example 2 in terms of water repellency but has high transmittance. The difference in water repellency between Example 1 and Example 2 is considered to be due to the difference in the water droplet contact angle.

[0076] It can be seen that Comparative Examples 1 to 3 have problems in both water droplet adhesion and replaceability. On the other hand, Comparative Example 4 has the same performance as Example 2 in terms of water repellency, but the fine concavo-convex structure layer is directly formed on the lens and has no replaceability. For Comparative Examples 1 to 4, since the lens is integrally formed as the structural module, the total light transmittance cannot be measured in principle, so no numerical values are described.

Industrial Applicability

[0077] According to the present invention, it is possible to easily provide a water repellent function, and to provide a structure 100 having a three-dimensional shape that follows the curved surface shape of the lens 401 of the sensor device 400 and a manufacturing method thereof. Thereby, a spatially stable structural module 500 can be provided without losing the functions and optical characteristics of the sensor device 400 to which the structure 100 is attached.

[0078] In addition, since the structure 100 formed by the present invention is detachable from the lens 401 of the sensor device 400, even if the water repellent function of the structure 100 is impaired, the water repellent function can be easily restored by replacing the structure 100. As long as the sensor device 400 is used in an outdoor environment, it is not realistic to completely avoid characteristic deterioration due to UV light or scratches on the surface of the structure 100. Therefore, even if the durability on the surface of the lens 401 by the structure 100 is lost, the water repellent function of the structural module 500 including the sensor device 400 and the structure 100 can be easily restored by replacing the structure 100.

Explanation of Signs

[0079] 100 Structure 101 Substrate 102 First fine concavo-convex structure layer 103 Second fine concavo-convex structure layer 1021 Base portion of the first fine concavo-convex structure layer 1031 Base portion of the second fine concavo-convex structure layer 151 First UV curable resin 152 Second UV curable resin 160 Roll laminator 201 First holding film 202 Second holding film 250 First intermediate structure 260 Second intermediate structure 300 Molding lens 400 Sensor device 401 Lens 500 Structure module

Claims

1. A structure attached to the outer surface of a sensor device having a curved surface shape, comprising: a substrate; fine concavo-convex structure layers disposed on both surfaces of the substrate; and is provided with, The fine concavo-convex structure layer, a first fine concavo-convex structure layer located on the sensor device side; a second fine concavo-convex structure layer located on the side opposite to the sensor device side; and has, The second fine concavo-convex structure layer has water repellency, The structure has a three-dimensional shape that follows the curved surface shape of the outer surface. Structure.

2. The structure according to claim 1, wherein the first fine concavo-convex structure layer has a pitch equal to or less than the wavelength of light detected by the sensor device.

3. The structure according to claim 1, which is configured to be detachable from the outer surface.

4. The structure according to claim 1, wherein the substrate has thermoplasticity.

5. The structure according to claim 1, having a total light transmittance of 98% or more.

6. The structure according to claim 1, wherein the water droplet contact angle of the second fine concavo-convex structure layer is 130 degrees or more.

7. The sensor device; and the structure according to any one of claims 1 to 6 attached to the outer surface of the sensor device. and is provided with, Structure module.

8. The structure module according to claim 7, wherein the radius of curvature of the outer surface is 5 mm or more and 500 mm or less.

9. The structure module according to claim 7, wherein the sensor device includes an in-vehicle camera module.

10. The structure module according to claim 7, wherein the sensor device includes a camera module for a surveillance camera.

11. A method for manufacturing the structure according to any one of claims 1 to 6, comprising: In a first pressing step, a first UV curable resin is sandwiched and pressed between a substrate and a first holding film having a fine concavo-convex structure on its surface so that the fine concavo-convex structure of the first holding film contacts the first UV curable resin; In a first curing step, the sandwiched first UV curable resin is cured by irradiation with UV light to form a first fine concavo-convex structure layer on one surface of the substrate; In a first peeling step, the first holding film is peeled off from the first fine concavo-convex structure layer; A second crimping step of sandwiching and crimping a second UV curable resin between the substrate and a second holding film having a fine concavo-convex structure on its surface so that the fine concavo-convex structure of the second holding film contacts the second UV curable resin; A second curing step of curing the sandwiched second UV curable resin by irradiation with UV light to form a second fine concavo-convex structure layer on the other surface of the substrate; A second peeling step of peeling the second holding film from the second fine concavo-convex structure layer; A manufacturing method of a structure, including a forming step of subjecting the substrate having fine concavo-convex structures formed on both surfaces to a vacuum heat treatment to form a three-dimensional shape following the curved surface shape of the outer surface of a sensor device to be attached.

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