Structure, structure module, and method for manufacturing structure

Abstract

Provided is a structure with which a water-repellent function can be imparted with ease, optical characteristics of a sensor device can be maintained, and also replacement can be easily performed on the sensor device.　Provided is a structure 100, which is attached to the outer surface of a sensor device 400, the outer surface having a curved shape, the structure comprising a base 101 and micro dip / bump-structured layers each arranged on one of the two surfaces of the base 101. The micro dip / bump-structured layers are constituted by a first micro dip / bump-structured layer 102 positioned on the sensor device 400 side, and a second micro dip / bump-structured layer 103 positioned on the opposite side from the sensor device 400 side. The second micro dip / bump-structured layer 103 has water repellency. The structure 100 has a three-dimensional shape following the curved shape of said outer surface.

Description

Structure, structure module, and method for manufacturing structure

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

[0002] Sensor devices used outdoors, such as in-vehicle camera modules used for in-vehicle rearview monitors or exterior sensing applications, and camera modules for surveillance cameras, are known. The exterior lenses of the sensors used in such sensor devices typically have a three-dimensional shape to achieve a light-gathering function. To avoid deterioration of visibility or image quality due to reflection of external light (such as color unevenness or ghosting), an anti-reflection treatment is often applied to the light incident surface of a substrate such as a lens. Known anti-reflection treatment methods include providing a multilayer anti-reflection film on the light incident surface or forming a fine uneven structure to reduce reflectance.

[0003] The above lenses require high durability because they are used outdoors and are exposed to external environments containing dust, water droplets, etc. A known method for protecting the lenses from dust, water droplets, etc. contained in the external environment is to apply a water-repellent coating to the outermost surface of the lenses.

[0004] For example, Patent Document 1 discloses a method of applying a water-repellent coating to a lens surface that has already been coated with an anti-reflection coating. However, when a water-repellent coating is applied to a microscopically flat surface, the contact angle is small, at around 100 degrees, resulting in insufficient water repellency. Although a super-water-repellent state can be achieved by coating with a nanoporous film, the water-repellent coating is removed when exposed to UV (Ultra-Violet) light or a kill resistance test, resulting in a loss of water repellency.

[0005] Patent Document 2 discloses a technology for reducing reflectivity by directly forming a concave-convex structure on the lens surface that is smaller than the wavelength of light detected by a sensor device. This reduces the reflectivity of the curved lens surface. Patent Document 2 also discloses a method for making the lens water-repellent by adding a water-repellent material to the lens's forming material. This is said to suppress the adhesion of water droplets or dust. However, with this method, it is difficult to restore the lens's performance once its water-repellent properties are lost due to the external environment.

[0006] Japanese Patent Publication No. 2003-161804

[0007] The above-mentioned conventional technology did not sufficiently consider the need to provide a structure that can be easily provided with water-repellent properties, maintains the optical properties of the sensor device, and can be easily replaced by being attached to the sensor device as a separate part.

[0008] The present invention aims to provide a structure that can be easily replaced with respect to a sensor device while easily imparting water-repellent properties and maintaining the optical properties of the sensor device, a structure module in which the structure is attached to a sensor device, and a method for manufacturing the structure.

[0009] That is, the gist of the present invention is as follows: (1) A structure to be attached to an outer surface of a sensor device having a curved outer surface, the structure comprising: a substrate and a microrelief structure layer disposed on both sides of the substrate, the microrelief structure layer having a first microrelief structure layer located on the sensor device side and a second microrelief structure layer located on the opposite side from the sensor device side, the second microrelief structure layer having water repellency, and the structure having a three-dimensional shape that follows the curved shape of the outer surface.

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

[0011] (3) The structure described in (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 thermoplastic properties.

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

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

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

[0016] (8) A structural 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), wherein the sensor device includes an in-vehicle camera module.

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

[0019] A method for producing a structure according to any one of (1) to (6) above, comprising: a first pressure-bonding step of sandwiching and pressing a first UV-curable resin between a substrate and a first support film having a microrelief structure on its surface so that the microrelief structure of the first support film is in contact with the first UV-curable resin; a first curing step of curing the sandwiched first UV-curable resin by irradiation with UV light to form a first microrelief structure layer on one side of the substrate; a first peeling step of peeling the first support film from the first microrelief structure layer; and a second UV-curable resin layer between the substrate and a second support film having a microrelief structure on its surface. A method for manufacturing a structure, comprising: a second pressure-bonding step of clamping and pressing a resin so that the other surface of the substrate and the micro-relief structure of the second support film are in contact with the second UV-curable resin; a second curing step of curing the clamped second UV-curable resin by irradiating it with UV light to form a second micro-relief structure layer on the other surface of the substrate; a second peeling step of peeling the second support film from the second micro-relief structure layer; and a molding step of performing a vacuum heating process on the substrate having micro-relief structures formed on both surfaces to mold it into a three-dimensional shape that follows the curved shape of the outer surface of the sensor device to be attached.

[0020] According to the present invention, it is possible to provide a structure that can be easily replaced with respect to a sensor device while easily imparting water-repellent properties and maintaining the optical properties of the sensor device, a structure module in which the structure is attached to a sensor device, and a method for manufacturing the structure.

[0021] FIG. 1 is a schematic cross-sectional view showing a structure according to one embodiment of the present invention. FIG. 2 is a schematic view showing one step in a method for manufacturing a structure according to one embodiment of the present invention. FIG. 3 is a schematic view showing one step in a method for manufacturing a structure according to one embodiment of the present invention. FIG. 4 is a schematic view showing one step in a method for manufacturing a structure according to one embodiment of the present invention. FIG. 5 is a schematic view showing one step in a method for manufacturing a structure according to one embodiment of the present invention. FIG. 6 is a schematic view showing one step in a method for manufacturing a structure according to one embodiment of the present invention. FIG. 7 is a schematic cross-sectional view showing the vicinity of a lens of a structure module in which a structure according to one embodiment of the present invention is mounted on a sensor device.

[0022] A structure according to one embodiment of the present invention (hereinafter, sometimes referred to as "the structure of this embodiment") will be described below.

[0023] (Structure) As shown in FIG. 1 , the structure 100 of this embodiment has a substrate 101 and microrelief structure layers disposed on both sides of the substrate 101. The microrelief structure layer has a first microrelief structure layer 102 and a second microrelief structure layer 103. The first microrelief structure layer 102 is located on the side of a sensor device 400 described below. The second microrelief structure layer 103 is located on the side opposite the sensor device 400. The second microrelief structure layer 103 is water-repellent. In this specification, "water-repellent" 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 shape of the outer surface of the sensor device 400.

[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 object in contact with the water droplet, and the line connecting one of the contact points between the water droplet and the object in contact with the water droplet, and the apex of the water droplet was measured using an optical reading device, and the obtained value was doubled.

[0025] In this specification, the term "three-dimensional shape that follows the curved shape of the outer surface" includes, for example, a three-dimensional shape that is the same as or corresponds to the curved shape of the outer surface of sensor device 400. For example, the term "three-dimensional shape that follows the curved shape of the outer surface" includes a three-dimensional shape that has a radius of curvature that is the same as or similar to the radius of curvature of the outer surface of sensor device 400. "Similar to the radius of curvature of the outer surface of sensor device 400" means, for example, that the radius of curvature of the outer surface preferably has an error of 10% or less, more preferably an error of 5% or less, and even more preferably an error of 1% or less.

[0026] In this specification, the wavelength of light detected by the sensor device 400 is in the visible light band (approximately 360 nm to 830 nm), and the total light transmittance means the transmittance of light in this band.

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

[0028] <Substrate> The substrate 101 used in this embodiment is typically preferably thermoplastic. The configuration of the substrate 101 used in this embodiment is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include a polycarbonate film. The substrate 101 is preferably transparent and has a thickness of 30 μm or more and 200 μm or less. The surface of the substrate 101 may also be coated.

[0029] <First Fine Relief Structure Layer> The first fine relief structure layer 102 used in this embodiment has a fine relief pattern (protrusions that are protruding in the thickness direction of the fine relief structure and recesses that are recessed in the thickness direction of the fine relief structure). This can improve anti-reflection performance. The protrusions and recesses may be arranged periodically (for example, in a houndstooth or rectangular lattice pattern) or randomly. There are no particular restrictions on the shapes of the protrusions and recesses, and they may be bullet-shaped, cone-shaped, columnar, needle-shaped, or the like. The shape of the recesses refers to the shape formed by the inner walls of the recesses.

[0030] The average period (pitch) of the concave-convex pattern of the first microrelief structure layer 102 is preferably equal to or less than the wavelength of light detected by the sensor device 400 used, more preferably equal to or less than the wavelength of visible light (for example, 830 nm or less), even more preferably equal to or less than 350 nm, and most preferably equal to or less than 280 nm. The average period (pitch) of the concave-convex pattern of the first microrelief structure layer 102 is more preferably equal to or greater than 100 nm, and even more preferably equal to or greater than 150 nm. By making the pitch of the concave-convex pattern of the first microrelief structure layer 102 equal to or less than the wavelength of visible light, i.e., by forming a so-called moth-eye structure, it is possible to further improve anti-reflection performance.

[0031] The average period of the concave-convex pattern is the arithmetic mean value of the distances between adjacent convex portions and concave portions. The concave-convex pattern can be observed, for example, using a scanning electron microscope (SEM) or a cross-sectional transmission electron microscope (TEM). The average period can be calculated, for example, by picking several combinations of adjacent convex portions and several combinations of adjacent concave portions, measuring the distances between the convex portions and the concave portions that make up each combination, and averaging the measured values.

[0032] The depth of the recesses (height of the protrusions) in the concave-convex pattern of the first microrelief structure layer 102 is not particularly limited, but is preferably 150 nm or more, more preferably 190 nm or more, and also preferably 300 nm or less, more preferably 230 nm or less. On the other hand, the thickness of the portion of the first microrelief structure layer 102 where the concave-convex pattern is not formed, i.e., the base portion 1021 (see FIG. 2D ), is preferably 250 nm or less. If the thickness of the portion of the first microrelief structure layer 102 that does not have a microrelief structure is 250 nm or less, the vibration (ripple) of the reflection spectrum caused by multiple reflections between the substrate 101 and the first microrelief structure layer 102 is reduced, and color unevenness or deterioration of reflection can be further suppressed. From the same viewpoint, the thickness of the portion of the first microrelief structure layer 102 that does not have a microrelief structure 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, from the viewpoint of practicality, the thickness of the portion of the first microrelief structure layer 102 that does not have the microrelief structure can be set to 0.01 nm or more. Note that the thickness of the portion of the first microrelief structure layer 102 that does not have the microrelief structure refers to the distance in the stacking direction or film thickness direction between the surface on which the microrelief structure is not formed and the apex of the deepest recess of the formed microrelief structure.

[0033] The first microrelief 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, but examples thereof include a UV-curable acrylic resin and a UV-curable epoxy resin.

[0034] <Second Microrelief Structure Layer> The second microrelief structure layer 103 used in this embodiment has water repellency. That is, the water droplet contact angle of the second microrelief 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 first fine concave-convex structure layer 102 described above, the second fine concave-convex structure layer 103 has a fine concave-convex pattern (protrusions that are convex in the thickness direction of the fine concave-convex structure and recesses that are concave in the thickness direction of the fine concave-convex structure). This can improve anti-reflection performance. The protrusions and recesses may be arranged periodically (for example, in a houndstooth or rectangular lattice pattern) or randomly. The shapes of the protrusions and recesses are not particularly limited and may be bullet-shaped, cone-shaped, columnar, needle-shaped, or the like.

[0036] The average period (pitch) of the concave-convex pattern of the second microrelief structure layer 103 is preferably equal to or less than the wavelength of visible light (for example, 830 nm or less), more preferably equal to or less than 350 nm, and even more preferably equal to or less than 280 nm. The average period (pitch) of the concave-convex pattern of the second microrelief structure layer 103 is more preferably equal to or greater than 100 nm, and even more preferably equal to or greater than 150 nm. By making the pitch of the concave-convex pattern of the second microrelief structure layer 103 equal to or less than the wavelength of visible light, which is a so-called moth-eye structure, it is possible to further improve the anti-reflection performance.

[0037] Furthermore, the depth of the recesses (height of the protrusions) in the concave-convex pattern of the second microrelief structure layer 103 is not particularly limited, but is preferably 150 nm or more, more preferably 190 nm or more, and also 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 of the second microrelief structure layer 103 where the concave-convex pattern is not formed, i.e., the base portion 1031 (FIG. 2H), is preferably 250 nm or less. If the thickness of the portion of the second microrelief structure layer 103 that does not have a microrelief structure is 250 nm or less, the vibration (ripple) of the reflection spectrum caused by multiple reflections between the substrate 101 and the second microrelief structure layer 103 is reduced, and color unevenness or deterioration of reflection can be further suppressed. From the same viewpoint, the thickness of the portion of the second microrelief structure layer 103 that does not have a microrelief structure 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, from the viewpoint of practicality, the thickness of the portion of the second microrelief structure layer 103 that does not have the microrelief structure can be set to 0.01 nm or more. Note that the thickness of the portion of the second microrelief structure layer 103 that does not have the microrelief structure refers to the distance in the stacking direction or film thickness direction between the surface on which the microrelief structure is not formed and the apex of the deepest recess of the formed microrelief structure.

[0038] The arrangement of the recesses and protrusions of the fine concave-convex structure portions of each of the first fine concave-convex structure layer 102 and the second fine concave-convex structure layer 103, the average period of the concave-convex pattern, the depth of the recesses, etc. may be the same as or different from each other.

[0039] The second microrelief 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, but examples thereof include a UV-curable acrylic resin and a UV-curable epoxy resin.

[0040] In this embodiment, the refractive indexes of the substrate 101, the first microrelief structure layer 102, and the second microrelief structure layer 103 are set to n ０ , n １ , n ２ When０ and １ The absolute value of the refractive index difference with n is within 0.2 and ０ and ２ The absolute value of the difference in refractive index between the first and second layers is preferably within 0.2. By satisfying this condition, the vibration (ripple) of the reflection spectrum caused by multiple reflections between layers is reduced, color unevenness or deterioration of reflection 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. The structure 100 has a three-dimensional shape that follows the curved shape of the outer surface of the sensor device 400.

[0042] (Method for manufacturing a structure) The method for manufacturing a structure of the present invention is characterized by including a first pressure-bonding step, a first curing step, a first peeling step, a second pressure-bonding step, a second curing step, a second peeling step, and a molding step. This method makes it possible to manufacture a structure in which a microrelief structure layer is disposed on both sides of a substrate, which has water repellency and is detachable from a sensor device 400 to be attached.

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

[0044] <First Compression Bonding Step> The first compression bonding step is a step of sandwiching and compressing a first UV-curable resin 151 between a substrate 101 and a first support film 201 having a microrelief structure on its surface, such that the microrelief structure of the first support film 201 contacts the first UV-curable resin 151. Specifically, in the first compression bonding step of the manufacturing method of this embodiment, as shown in FIG. 2A , first, the first UV-curable resin 151 is sandwiched between the substrate 101 and the first support film 201 having a microrelief structure on its surface, such that the microrelief structure of the first support film 201 contacts the first UV-curable resin 151. This results in a first sandwiched body. The first UV-curable resin 151 is not particularly limited, but examples thereof include UV-curable acrylic resins and UV-curable epoxy resins. Furthermore, various additives such as a curing initiator may be added to the first UV curable resin 151 as required.

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

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

[0047] The material constituting the base substrate is not particularly limited, but is preferably transparent and break-resistant, such as PET (polyethylene terephthalate), TAC (triacetyl cellulose), or PC (polycarbonate). Formation of a finely textured layer on the base substrate can be achieved, for example, by carrying out a method including the steps of: applying an uncured UV-curable resin to one side of the base substrate; adhering a roll having a corresponding textured pattern to the applied UV-curable resin to transfer the textured pattern to the UV-curable resin; irradiating the applied UV-curable resin with UV light to cure it; and peeling the cured UV-curable resin from the roll. The UV-curable resin is not particularly limited, but examples include UV-curable acrylic resins and UV-curable epoxy resins. Various additives, such as curing initiators, may be added to the UV-curable resin as needed.

[0048] In order to improve the releasability of the first support film 201, the surface of the fine uneven structure may be coated with a film made of an inorganic material.

[0049] 2A , the first sandwiching body is pressed in the clamping direction by a pressing device such as a roll laminator 160. Here, in the first pressing step, the thickness of the first microrelief structure layer 102 to be finally obtained can be adjusted by adjusting the pressure during pressing.

[0050] <First Curing Step> The first curing step is a step of curing the sandwiched first UV-curable resin 151 by irradiating it with UV light to form a first microrelief structure layer 102 on one side of the substrate 101. Specifically, in the first curing step in the manufacturing method of this embodiment, as shown in FIG. 2B , UV light is irradiated onto the first UV-curable resin 151 sandwiched in the first pressure-bonding step to harden the first UV-curable resin 151. By hardening the first UV-curable resin 151, a first intermediate structure 250 is obtained in which the first microrelief structure layer 102 is formed on one side of the substrate 101, as shown in FIG. 2C . Note that the first curing step may be performed at the same time as the first pressure-bonding step. The microrelief structure on the surface of the first microrelief structure layer 102 obtained in this manner can be seamlessly interlocked with the microrelief structure of the first support film 201.

[0051] <First Peeling Step> The first peeling step is a step of peeling the first support film 201 from the first microrelief structure layer 102. The first peeling step can be performed after the first curing step. Specifically, in the first peeling step in the manufacturing method of this embodiment, the first support film 201 present on the first intermediate structure 250 shown in FIG. 2C is peeled off to produce the state shown in FIG. 2D.

[0052] <Second Pressure-Bonding Step> The second pressure-bonding step is a step of sandwiching and pressure-bonding the second UV-curable resin 152 between the substrate 101 and a second support film 202 having a microrelief structure on its surface, such that the other surface of the substrate 101 and the microrelief structure of the second support film 202 contact the second UV-curable resin 152. The second pressure-bonding step can be performed after the first peeling step. Specifically, in the second pressure-bonding step in the manufacturing method of this embodiment, as shown in FIG. 2E , the other surface of the substrate 101, i.e., the surface of the substrate 101 opposite the first microrelief structure layer 102, is sandwiched between the second UV-curable resin 152 and the second support film 202 having a microrelief structure on its surface, such that the microrelief structure of the second support film 202 contacts the second UV-curable resin 152. This results in a second sandwiched body. The second UV-curable resin 152 is not particularly limited, and examples thereof include UV-curable acrylic resins and UV-curable epoxy resins. It is preferable to add an additive that exhibits water repellency to the second UV-curable resin 152. This allows the second microrelief structure layer 103, which will be formed later, to have water repellency. Furthermore, various additives, such as a curing initiator, may be added to the second UV-curable resin 152 as needed.

[0053] Here, examples of additives that exhibit water repellency include fluororesin, silicone resin, etc. The amount of the additive added to the second UV curable resin 152 is, for example, preferably 0.01% by mass or more and 5% by mass or less, and more preferably 0.1% by mass or more and 2% by mass or less, relative to the second UV curable resin 152.

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

[0055] Here, the second support film 202 can be produced in the same manner as the first support 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 improve the releasability of the second support film 202, the surface of the fine uneven structure may be coated with a film made of an inorganic material.

[0057] 2E, the second sandwiching body is pressed in the clamping direction by a pressing device such as a roll laminator 160. Here, in the second pressing step, the thickness of the second microrelief structure layer 103 to be finally obtained can be adjusted by adjusting the pressure during pressing.

[0058] <Second Curing Step> The second curing step is a step of curing the sandwiched second UV-curable resin 152 by irradiating it with UV light to form a second microrelief structure layer 103 on the other surface of the substrate 101. The operation of the second curing step is substantially the same as that of the first curing step. Specifically, in the second curing step of the manufacturing method of this embodiment, as shown in FIG. 2F , the second UV-curable resin 152 sandwiched in the second pressure-bonding step is irradiated with UV light to harden the second UV-curable resin 152. By hardening the second UV-curable resin 152, a second intermediate structure 260 is obtained in which the second microrelief structure layer 103 is formed on the other surface of the substrate 101 (the surface of the first intermediate structure 250), as shown in FIG. 2G . The second curing step may be performed at the same time as the second pressure-bonding step. The microrelief structure on the surface of the second microrelief structure layer 103 obtained in this manner can be fitted into the microrelief structure of the second support film 202 without any gaps.

[0059] <Second Peeling Step> The second peeling step is a step of peeling the second support film 202 from the second microrelief structure layer 103. 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 this embodiment, the second support film 202 present on the second intermediate structure 260 is peeled off to produce the state shown in FIG. 2H.

[0060] <Shaping Process> The molding process involves subjecting the substrate 101, on both sides of which a microrelief structure is formed, to a vacuum heat treatment to form a three-dimensional shape that conforms to the curved shape of the outer surface of the sensor device 400 to which it is to be attached. In the molding process of the manufacturing method of this embodiment, first, a lens having a curvature similar 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 vacuum heat treatment method is not particularly limited, and examples include a method using a heated dryer in a vacuum chamber. In this way, a structure 100 having a three-dimensional shape that conforms to the curved shape of the outer surface is obtained. By forming the structure 100 into such a three-dimensional shape, the structure 100 can be attached to the sensor device 400 in a spatially stable state without impairing the function and optical properties of the sensor device 400, as described below.

[0061] (Structure Module) As shown in FIG. 3 , the structure module 500 of this embodiment has 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 at the outermost position of the sensor device 400. The outer surface of the sensor device 400, i.e., the outer surface of the lens 401, has a curved 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. Methods for attaching the structure 100 to the outer surface include screws, physical clamps, and methods using adhesives, etc.

[0062] <Use of Structure Module> In the structure module 500 of this embodiment, the sensor device 400 may include an in-vehicle camera module or a camera module for a surveillance camera. That is, the structure 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.

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

[0064] Example 1 As shown in FIG. 3 , a structure 100 was fabricated having a substrate 101, with a first microrelief structure layer 102 and a second microrelief structure layer 103 formed on both sides of the substrate 101, and a three-dimensional shape that conforms to the curved shape of the outer surface of a sensor device 400. A structure module 500 in which the structure 100 was attached to the lens 401 of the sensor device 400 was used as a model. A polycarbonate film with a thickness of 150 μm was used as the substrate 101 of the structure 100. The first microrelief structure layer 102 was formed using a UV acrylic resin, and the microrelief structure had a moth-eye structure with a pitch of 200 nm and a depth of the recesses (height of the protrusions) of 200 nm. The second microrelief structure layer 103 was formed using a resin mixture in which approximately 2% by mass of fluororesin was added to the UV acrylic resin. The microrelief structure of the second microrelief structure layer 103 was a moth-eye structure with a pitch of 200 nm and a depth of the recesses (height of the protrusions) of 200 nm. The thickness of the base portion 1021 (a portion where the microrelief structure is not formed) of the first microrelief structure layer 102 was 3000 nm. The thickness of the base portion 1031 of the second microrelief structure layer 103 was 3000 nm. The refractive index n of the substrate 101 was ０ The refractive index n of the first microrelief structure layer 102 was set to 1.6. １ The refractive index n of the second microrelief structure layer 103 was set to 1.52. ２ was set to 1.52.

[0065] According to the manufacturing method of the present invention, a first microrelief structure layer 102 and a second microrelief structure layer 103 were formed on both sides of a 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 similar to that of the outer surface of a sensor device 400 to which the final structure 100 would be attached was prepared. The second intermediate structure 260 was placed on the molding lens 300 so that the first microrelief structure layer 102 faced the lens side, and vacuum heating treatment was performed to mold it into a three-dimensional shape following the curved shape of the molding lens 300, thereby obtaining a structure 100. The vacuum heating treatment was performed using a heated dryer in a vacuum chamber. The total light transmittance of the molded structure 100 for light from the second microrelief structure layer 103 side was 99%. Furthermore, the resulting structure 100 was attached with adhesive tape to the outer edge of the non-effective lens area on the outer surface of a camera module to produce a structure module 500. The curvature of the outer surface of the camera module used here was approximately 15 mm.

[0066] Next, the water droplet contact angle of the outer surface of the structure 100 (the surface of the second microrelief structure layer 103) was measured, and a water droplet adhesion test was performed when the sample (structure module 500) was installed at a 45-degree inclination, and when the sample was installed approximately horizontally. The water droplet adhesion test involved dropping pure water onto the second microrelief structure layer 103 of the sample with a dropper, and checking whether the dropped water droplet flowed after touching the sample, and evaluation was performed based on the following evaluation criteria. After these tests, the attached structure 100 was peeled off from the camera module and checked to see if it could be reattached, and replaceability was evaluated based on the following evaluation criteria. The results are shown in Table 1.

[0067] The evaluation criteria for the water droplet adhesion test in Table 1 are as follows: A: Water droplets are repelled and do not adhere to the sample. B: Water droplets are repelled immediately after the start of the test, but begin to adhere after about 60 seconds. C: Water droplets adhere to the surface.

[0068] The evaluation criteria for exchangeability in Table 1 are as follows: A: Exchange and function restoration are possible. C: Exchange and function restoration are impossible.

[0069] Example 2 A structure module 500 similar to that of Example 1 was used as a model, except that the second microrelief structure layer 103 was made of UV acrylic resin with approximately 2% added fluororesin, and had a moth-eye structure with a recess depth (protrusion height) of 400 nm as the microrelief structure. The total light transmittance of the produced structure 100 from the second microrelief structure layer 103 side was 99%. Water droplet contact angle, water droplet adhesion test, and exchangeability test were performed in the same manner as in Example 1. The results are shown in Table 1.

[0070] (Comparative Example 1) A structural module model was used in which a multilayer film made of a dielectric material was directly formed on a lens having a curved surface. The surface of the multilayer film was smooth, and the total thickness of the multilayer film was approximately 0.2 μm. Tests for water droplet contact angle and water droplet adhesion were carried out in the same manner as in Example 1. For evaluation of replaceability, since the multilayer film was directly formed, whether it could be removed with a router or the like and then re-formed was evaluated. The results are shown in Table 1.

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

[0072] Comparative Example 3: A model of a structural module in which a moth-eye structure was formed directly on a lens having a curved surface was used. The lens was subjected to a silane coupling treatment, and a fine uneven structure was formed on the surface of the lens using UV acrylic resin. The fine uneven structure was present only on the surface of the structural module, and the surface of the UV acrylic resin in contact with the lens was smooth. Here, the pitch of the moth-eye structure was 200 nm, and the depth of the recesses (height of the protrusions) was 200 nm. Water droplet contact angle and water droplet adhesion tests were conducted in the same manner as in Example 1, and an exchangeability test was conducted in the same manner as in Comparative Example 1. The results are shown in Table 1.

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

[0074]

[0075] Table 1 shows that the structure modules 500 according to Examples 1 and 2 have a water droplet contact angle of 130 degrees or more, are interchangeable, and have a total light transmittance of 98% or more. Furthermore, in a water droplet adhesion test in which the sample (structure module 500) was tilted at a 45-degree angle, no water droplets adhered to either Example 1 or Example 2. In a water droplet adhesion test in which the sample was placed horizontally, water droplets began to adhere to Example 1 approximately 60 seconds after the water droplets were applied, while no water droplets adhered to Example 2. From the above, it can be seen that Example 2 is a structure 100 that has high transmittance and water repellency and is detachable from the sensor device 400. On the other hand, Example 1 is inferior to Example 2 in terms of water repellency, but has high transmittance and is detachable from the sensor device 400. The difference in water repellency between Example 1 and Example 2 is thought to be due to the difference in water droplet contact angle.

[0076] It can be seen that Comparative Examples 1 to 3 have issues with 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 concave-convex structure layer is formed directly on the lens, and therefore is not replaceable. Note that for Comparative Examples 1 to 4, since the lens is integrally constructed as a structural module, it is not possible in principle to measure the total light transmittance, and therefore no numerical values ​​are listed.

[0077] According to the present invention, it is possible to provide a structure 100 that can be easily imparted with water-repellent properties and has a three-dimensional shape that follows the curved shape of the lens 401 of the sensor device 400, and a method for manufacturing the same. This makes it possible to provide a spatially stable structure module 500 without losing the functionality and optical properties of the sensor device 400 to which the structure 100 is attached.

[0078] Furthermore, because the structure 100 formed according to 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. Since the sensor device 400 is used in an outdoor environment, it is not realistic to completely avoid deterioration of the characteristics of the structure 100 or scratches on the surface due to UV light. Therefore, even if the durability of the structure 100 on the surface of the lens 401 is lost, the water-repellent function of the structure module 500 including the sensor device 400 and the structure 100 can be easily restored by replacing the structure 100.

[0079] 100 Structure 101 Substrate 102 First microrelief structure layer 103 Second microrelief structure layer 1021 Base portion of first microrelief structure layer 1031 Base portion of second microrelief 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 Structural module

Claims

1. A structure to be attached to the outer surface of a sensor device having a curved outer surface, comprising: a substrate; and a fine-relief structure layer disposed on both sides of the substrate, the fine-relief structure layer having a first fine-relief structure layer located on the sensor device side, and a second fine-relief structure layer located on the opposite side to the sensor device side, the second fine-relief structure layer being water-repellent, and the structure having a three-dimensional shape that follows the curved shape of the outer surface.

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

3. The structure of claim 1, configured to be detachable from said outer surface.

4. The structure of claim 1, wherein the substrate comprises a thermoplastic material.

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 second fine concave-convex structure layer has a water droplet contact angle of 130 degrees or more.

7. A structure module comprising: the sensor device; and a structure according to any one of claims 1 to 6 attached to the outer surface of the sensor device.

8. The structural 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 structural module of claim 7, wherein the sensor device includes an on-board camera module.

10. The structural module of claim 7, wherein the sensor device comprises a camera module for a surveillance camera.

11. A method for producing a structure according to any one of claims 1 to 6, comprising: a first pressure-bonding step of sandwiching and pressing a first UV-curable resin between a substrate and a first support film having a fine uneven structure on its surface such that the fine uneven structure of the first support film is in contact with the first UV-curable resin; a first curing step of curing the sandwiched first UV-curable resin by irradiation with UV light to form a first fine uneven structure layer on one side of the substrate; a first peeling step of peeling the first support film from the first fine uneven structure layer; and a second pressure-bonding step of sandwiching and pressing a second UV-curable resin between the substrate and a second support film having a fine uneven structure on its surface such that the other side of the substrate and the fine uneven structure of the second support film are in contact with the second UV-curable resin. A method for manufacturing a structure, comprising: a second curing step of curing the sandwiched second UV-curable resin by irradiation with UV light to form a second microrelief structure layer on the other side of the substrate; a second peeling step of peeling the second support film from the second microrelief structure layer; and a molding step of performing a vacuum heating treatment on the substrate having a microrelief structure formed on both sides to mold it into a three-dimensional shape that follows the curved shape of the outer surface of a sensor device to be attached.

Images