JP7484979B2 - Infrared sensor cover, infrared sensor module and camera - Google Patents

Description

The present invention relates to an infrared sensor cover, an infrared sensor module, and a camera.

An infrared sensor is a technology that receives light in the infrared range, converts it into an electrical signal, and extracts and applies the necessary information, as well as devices that utilize this technology. It has features such as the ability to see objects without stimulating the human eye, and the ability to instantly measure the temperature of an object from a distance without contact. Because of these features, it is used in applications such as imaging devices such as cameras and non-contact temperature measuring devices.

In general, an infrared sensor is provided with a cover around the body to protect the body of the infrared sensor. For example, Patent Document 1 discloses an infrared sensor in which the body of the infrared sensor is covered with a cover made of polyethylene resin.

JP 2013-088248 A

However, the infrared sensor disclosed in Patent Document 1 has a cover made of a simple polyethylene resin, which does not have sufficient infrared transmittance and results in poor performance of the infrared sensor.
Glass or resin is often used as a cover for an infrared sensor, but simply using glass or resin may not provide sufficient infrared transmittance, which may result in poor performance of the infrared sensor. In particular, in applications that require high-performance infrared sensors, higher infrared transmittance is required.

The present invention aims to solve these problems and provide an infrared sensor cover that has excellent infrared transmittance, particularly near-infrared transmittance. The present invention also aims to provide an infrared sensor module that uses the infrared sensor cover, and a camera that uses the infrared sensor cover.

The present invention has the following aspects.
<1> A near-infrared sensor cover, comprising: an antireflection layer including a multilayer structure on one surface of a substrate; and an antireflection layer including a moth-eye structure on the other surface of the substrate,
a near-infrared sensor cover in which an average spacing between adjacent convex portions of the moth-eye structure is 20 nm to 400 nm, an average height of the convex portions is 60 nm to 400 nm, an aspect ratio which is a ratio of the average height of the convex portions to the average spacing between the convex portions is 0.8 to 5.0, and a transmittance at a wavelength of 950 nm is 93% or more.
<2> The near-infrared sensor cover according to <1>, wherein the material of the substrate is glass or resin.
<3> The near-infrared sensor cover according to <2>, wherein the material of the substrate is glass.
<4> The antireflection layer including the moth-eye structure has a substrate and a moth-eye structure, and the substrate is made of an acrylic resin, a polycarbonate resin, a polyester resin, or a cellulose resin. The near-infrared sensor cover according to any one of <1> to <3>.
<5> The near-infrared sensor cover according to any one of <1> to <4>, wherein the multilayer structure includes a plurality of layers having different refractive indices.
<6> The near-infrared sensor cover according to any one of <1> to <5>, having a transmittance of 93% or more at a wavelength of 850 nm.
<7> A near-infrared sensor module including the near-infrared sensor cover according to any one of <1> to <6> and a near-infrared sensor body.
<8> A camera comprising the near-infrared sensor cover and the near-infrared sensor body described in any one of <1> to <6>.
The present invention also has the following aspects.
[1] An infrared sensor cover having a substrate and an anti-reflection layer provided on at least one surface of the substrate.
[2] The infrared sensor cover according to [1], wherein the antireflection layer is an antireflection layer having a multilayer structure or an antireflection layer having a moth-eye structure.
[3] The infrared sensor cover described in [2], wherein the multilayer structure includes multiple layers having different refractive indices.
[4] The infrared sensor cover according to [2], wherein the average distance between adjacent protrusions of the moth-eye structure is 400 nm or less.
[5] The infrared sensor cover according to any one of [1] to [4], wherein the material of the substrate is glass or resin.
[6] The infrared sensor cover according to [5], wherein the material of the substrate is glass.
[7] An infrared sensor cover according to any one of [1] to [6], in which an antireflection layer including a multilayer structure is provided on one surface of the substrate, and an antireflection layer including a moth-eye structure is provided on the other surface of the substrate.
[8] An infrared sensor cover according to any one of [1] to [7], wherein the infrared rays are near-infrared rays.
[9] An infrared sensor cover according to any one of [1] to [8], having a transmittance of 93% or more at a wavelength of 850 nm.
[10] An infrared sensor cover according to any one of [1] to [9], having a transmittance of 93% or more at a wavelength of 950 nm.
[11] An infrared sensor module including an infrared sensor cover and an infrared sensor body according to any one of [1] to [10].
[12] A camera comprising an infrared sensor cover and an infrared sensor body according to any one of [1] to [10].

The present invention is excellent in infrared transmittance, particularly in near-infrared transmittance.
Furthermore, the infrared sensor module of the present invention has excellent infrared transmittance, particularly excellent near-infrared transmittance, and therefore has excellent performance as an infrared sensor module.
Furthermore, the camera of the present invention has excellent infrared transmittance, particularly excellent near-infrared transmittance, and therefore has excellent camera performance.

1 is a schematic cross-sectional view showing an embodiment of an infrared sensor cover of the present invention.

(Infrared sensor cover)
The infrared sensor cover of the present invention has a substrate and an antireflection layer provided on at least one surface of the substrate.
Fig. 1 shows one embodiment of the infrared sensor cover of the present invention. The infrared sensor cover 10 shown in Fig. 1 has an antireflection layer 30 including a multilayer structure on one surface of a substrate 20, and an antireflection layer 40 including a moth-eye structure on the other surface of the substrate 20. The antireflection layer 30 including a multilayer structure has a high refractive index layer 31 and a low refractive index layer 32. The antireflection layer 40 including a moth-eye structure has a substrate 41 and a moth-eye structure layer 42.

(substrate)
The material of the substrate is not particularly limited as long as it is a material that transmits infrared rays, and examples thereof include resins such as acrylic resins, polycarbonate resins, styrene resins, cellulose resins, polyester resins, polyolefin resins, etc.; glass, etc. Among these substrate materials, glass and resins are preferred because they have excellent infrared ray transmittance, and glass is more preferred.

The surface of the substrate may be subjected to a coating treatment, a corona treatment, or the like for the purpose of improving properties such as adhesion and scratch resistance.
The shape of the substrate can be appropriately selected depending on the application of the infrared sensor.

(Anti-Reflection Layer)
Examples of the antireflection layer include an antireflection layer including a multilayer structure in which antireflection performance is imparted by the interference of reflected waves, an antireflection layer including a moth-eye structure in which antireflection performance is imparted by a fine uneven structure, etc. Among these antireflection layers, the antireflection layer including a multilayer structure and the antireflection layer including a moth-eye structure are preferred because they have excellent infrared transmittance, and the antireflection layer including a moth-eye structure is more preferred because they have even more excellent infrared transmittance.

The infrared sensor cover of the present invention has an anti-reflection layer on at least one surface of the substrate, but since this has excellent infrared transmittance, it is preferable that the anti-reflection layer is provided on both surfaces of the substrate, and it is more preferable that the anti-reflection layer including a multilayer structure is provided on one surface of the substrate, and the anti-reflection layer including a moth-eye structure is provided on the other surface of the substrate.

(Anti-reflection layer including multi-layer structure)
The antireflection layer including a multilayer structure is provided with antireflection performance by the interference of reflected waves. The antireflection layer including a multilayer structure is not particularly limited as long as the refractive index of the multilayer structure is adjusted so that the antireflection performance is provided by the interference of reflected waves, and a known antireflection layer including a multilayer structure can be used.

The multilayer structure preferably includes multiple layers with different refractive indices, since the interference of reflected waves provides anti-reflection performance.

Between the anti-reflection layer including the multi-layer structure and the substrate, an adhesive layer for improving adhesion, a hard coat layer for improving scratch resistance, a base material for laminating the multi-layer structure, etc. may be provided.

(Anti-reflection layer including moth-eye structure)
The antireflection layer including the moth-eye structure is endowed with antireflection properties by the minute unevenness structure.
The fine concave-convex structure is composed of a plurality of convex portions and concave portions formed between the plurality of convex portions.

The average interval between adjacent convex portions of the fine uneven structure is preferably 20 nm to 400 nm, more preferably 80 nm to 300 nm. When the average interval between adjacent convex portions of the fine uneven structure is 20 nm or more, convex portions are easily formed when a plurality of pores of anodized porous alumina are transferred to form the convex portions. When the average interval between adjacent convex portions of the fine uneven structure is 400 nm or less, when a plurality of pores of anodized porous alumina are transferred to form the convex portions, the voltage for increasing the pore interval can be suppressed, and anodized porous alumina can be easily produced industrially.
In this specification, the average distance between adjacent convex portions is defined as the average value obtained by measuring the distance between adjacent convex portions (the distance from the center of a convex portion to the center of an adjacent convex portion) at 10 random points using electron microscope observation.

The average height of the convex portions is preferably 60 nm to 400 nm, more preferably 90 nm to 350 nm. When the average height of the convex portions is 60 nm or more, the increase in the minimum reflectance and the reflectance at a specific wavelength can be suppressed, and the antireflection performance is excellent. Furthermore, when the average height of the convex portions is 400 nm or less, the convex portions are easily formed, and the convex portions have excellent scratch resistance.
In this specification, the average height of a convex portion is defined as the average value of the vertical distance between the top of a convex portion and the bottom of an adjacent concave portion measured at 10 random points using an electron microscope.

The aspect ratio of the convex portions (average height of the convex portions/average distance between adjacent convex portions) is preferably 0.8 to 5.0, more preferably 1.2 to 4.0, and even more preferably 1.5 to 3.0. When the aspect ratio of the convex portions is 0.8 or more, the anti-reflection performance is excellent. Furthermore, when the aspect ratio of the convex portions is 5.0 or less, the convex portions are easy to form and have excellent scratch resistance.

Examples of the shape of the convex portion include a cone shape, a pyramid shape, a bell shape, and a cylinder shape. These convex portions may be used alone or in combination of two or more. Among these convex portions, the shape in which the cross-sectional area of the convex portion in the direction perpendicular to the height direction increases continuously from the apex in the depth direction is preferred, since the refractive index can be continuously increased from the air to the surface of the material on which the fine uneven structure is formed, thereby achieving anti-reflection performance that combines low reflectance and low wavelength dependency, and the cone shape, pyramid shape, and bell shape are more preferred.
The convex portion may be a single convex portion formed by merging a plurality of fine convex portions together.

Examples of methods for producing the fine concave-convex structure include the following method 1, method 2, and method 3.
Method 1: A method of performing injection molding or press molding using a mold having an inverted structure of a microrelief structure on its surface, thereby forming a microrelief structure directly on the surface of a substrate. Method 2: A method of sandwiching an active energy ray-curable composition between a mold having an inverted structure of a microrelief structure and a substrate, curing the active energy ray-curable composition to form a cured resin layer, and then separating the cured resin layer and the mold. Method 3: A method of sandwiching an active energy ray-curable composition between a mold having an inverted structure of a microrelief structure and a substrate, transferring the microrelief structure of the mold to the active energy ray-curable composition, separating the mold, and curing the active energy ray-curable composition to form a cured resin layer. Among these methods for producing a microrelief structure, methods 2 and 3 are preferred, and method 2 is more preferred, because they provide excellent transferability of the microrelief structure and excellent freedom in surface composition.

Examples of molds include a mold in which an inverted microrelief structure is formed on the surface by lithography, a mold in which an inverted microrelief structure is formed on the surface by laser processing, a mold in which anodized porous alumina having multiple pores is formed on the surface, and a replica mold in which a mother mold having a microrelief structure is replicated by electroforming or the like. Among these molds, a mold in which anodized porous alumina having multiple pores is formed on the surface is preferred, since it has excellent anti-reflection performance and is easy to form a large-area microrelief structure at low cost.

Examples of the lithography method include electron beam lithography and laser interference lithography.
Examples of methods for producing a mold having a reversed fine relief structure formed on its surface by lithography include a method in which a photoresist film is applied to the surface of a substrate, and the photoresist film is exposed to an ultraviolet laser, an electron beam, an X-ray, or the like, and then developed to obtain a mold having a fine relief structure formed on its surface by a resist pattern; and a method in which the substrate is selectively etched by dry etching or the like through the resist pattern, and the resist pattern is removed to obtain a mold having a fine relief structure formed directly on the surface of the substrate.

One example of a method for manufacturing a mold with anodized porous alumina having multiple pores on its surface is to anodize aluminum at a specified voltage using an electrolyte such as oxalic acid, sulfuric acid, or phosphoric acid.

As a method for producing a mold having anodized porous alumina formed on the surface, for example, there is a method in which aluminum is anodized at a predetermined voltage using oxalic acid, sulfuric acid, phosphoric acid or the like as an electrolyte.
According to the method of anodizing aluminum at a predetermined voltage using oxalic acid, sulfuric acid, phosphoric acid, etc. as an electrolyte, high purity aluminum is anodized for a long time at a constant voltage, and then all or part of the oxide film is removed and anodized again, so that anodized porous alumina in which highly regular pores are formed in a self-organized manner can be formed. In addition, by combining anodizing treatment and pore size expansion treatment in the second anodizing process, it is possible to form pores whose cross section is not rectangular but triangular or bell-shaped. Furthermore, by appropriately adjusting the time, number of times, conditions, etc. of anodizing treatment and pore size expansion treatment, it is also possible to make the angle of the innermost part of the pores sharp.
A specific example of a method for manufacturing a mold having anodized porous alumina formed on its surface is the method described in JP-A-2015-129706.

Examples of mold shapes include flat, belt, and roll shapes. Among these mold shapes, belt and roll shapes are preferred because they allow for continuous transfer of the fine uneven structure and provide excellent productivity for the substrate.

The fine unevenness is preferably made of a cured resin layer, since it is possible to form the fine unevenness more easily.
The cured resin layer is a layer made of a cured product of an active energy ray-curable composition.

The active energy ray-curable composition is a composition that undergoes a polymerization reaction and is cured when irradiated with active energy rays.
Examples of active energy rays include visible light, ultraviolet light, electron beams, plasma, heat rays (infrared rays, etc.), etc. Among these active energy rays, ultraviolet light and electron beams are preferred, and ultraviolet light is more preferred, since they provide excellent curing properties for the active energy ray-curable composition.

The active energy ray-curable composition preferably contains a polymerizable compound, a polymerization initiator, and, if necessary, other additives.

Examples of polymerizable compounds include monomers, oligomers, reactive polymers, etc. that contain at least one of radically polymerizable bonds and cationic polymerizable bonds in the molecule. These polymerizable compounds may be used alone or in combination of two or more types.

Examples of the monomer having a radical polymerizable bond include monofunctional monomers having a (meth)acryloyl group, a vinyl group, etc., and polyfunctional monomers having a (meth)acryloyl group, a vinyl group, etc. These monomers having a radical polymerizable bond may be used alone or in combination of two or more kinds.
In this specification, (meth)acrylic refers to acrylic, methacrylic or both.

Examples of monomers having a cationic polymerizable bond include monomers having an epoxy group, an oxetanyl group, an oxazolyl group, a vinyloxy group, etc. These monomers having a cationic polymerizable bond may be used alone or in combination of two or more types.

Examples of oligomers or reactive polymers containing at least one of radically polymerizable bonds and cationic polymerizable bonds in the molecule include unsaturated polyester compounds such as condensates of unsaturated dicarboxylic acids and polyhydric alcohols; polyester (meth)acrylates; polyether (meth)acrylates; polyol (meth)acrylates; epoxy (meth)acrylates; urethane (meth)acrylates; cationic polymerization type epoxy compounds; homopolymers or copolymers of monomers having the above radically polymerizable bonds in their side chains, and the like. These oligomers or reactive polymers containing at least one of radically polymerizable bonds and cationic polymerizable bonds in the molecule may be used alone or in combination of two or more.

Examples of polymerization initiators include known photopolymerization initiators, known electron beam polymerization initiators, known thermal polymerization initiators, etc. These polymerization initiators may be used alone or in combination of two or more.

Examples of other additives include non-reactive polymers, antioxidants, release agents, lubricants, plasticizers, antistatic agents, light stabilizers, flame retardants, flame retardant assistants, polymerization inhibitors, UV absorbers, fillers, silane coupling agents, reinforcing agents, inorganic fillers, and impact resistance modifiers. These other additives may be used alone or in combination of two or more.

When imparting water repellency to the surface of the microrelief structure (specifically, making the contact angle between the microrelief structure and water 90° or more), it is preferable to use a fluorine-containing compound or a silicone-based compound as an active energy ray-curable composition capable of forming a hydrophobic material.

When imparting hydrophilicity to the surface of the microrelief structure (specifically, making the contact angle between the microrelief structure and water 25° or less), it is preferable to use a combination of a tetrafunctional or higher polyfunctional (meth)acrylate and a difunctional or higher hydrophilic (meth)acrylate as an active energy ray curable composition capable of forming a hydrophilic material.

Specific compositions of the active energy ray-curable composition include, for example, compositions described in JP-A-2013-175733 and JP-A-2015-129947.

Examples of methods for sandwiching the active energy ray curable composition between the mold and the substrate include a method in which the active energy ray curable composition is placed between the mold and the substrate, and the mold and the substrate are pressed together to inject the active energy ray curable composition into the fine uneven structure of the mold.

Examples of materials for the substrate include acrylic resins such as polymethyl methacrylate; polycarbonate resins; styrene resins such as polystyrene and methyl methacrylate-styrene copolymers; cellulose resins such as cellulose diacetate, cellulose triacetate, and cellulose acetate butyrate; polyester resins such as polyethylene terephthalate; polyamide resins; polyimide resins; polyethersulfone resins; polysulfone resins; polyolefin resins such as polypropylene, polymethylpentene, and alicyclic polyolefins; vinyl chloride resins such as polyvinyl chloride; polyvinyl acetal resins; polyether ketone resins; polyurethane resins; and glass. Among these substrate materials, acrylic resins, polycarbonate resins, polyester resins, and cellulose resins are preferred because of their excellent transmittance of external radiation, and polyester resins and cellulose resins are more preferred.

Examples of the substrate form include known forms such as films and sheets. Among these substrate forms, films and sheets are preferred because of their excellent productivity and ease of handling.

Methods for manufacturing the substrate include, for example, known manufacturing methods such as injection molding, extrusion molding, and cast molding. Among these methods for manufacturing the substrate, extrusion molding and cast molding are preferred because of their excellent productivity.

The surface of the substrate may be subjected to a coating treatment, corona treatment, etc., for the purpose of improving properties such as adhesion, antistatic properties, scratch resistance, and weather resistance.

(For infrared sensor covers)
The infrared ray targeted by the infrared sensor cover of the present invention is preferably near-infrared ray, more preferably 700 nm to 1500 nm, and even more preferably 800 to 1000 nm, because it has a better transmittance.

The transmittance of the infrared sensor cover of the present invention at a wavelength of 850 nm is preferably 93% or more, more preferably 95% or more, and even more preferably 97% or more, since the transmittance of infrared rays, particularly near-infrared rays, is excellent.
The transmittance of the infrared sensor cover of the present invention at a wavelength of 950 nm is preferably 93% or more, more preferably 95% or more, and even more preferably 97% or more, since the transmittance of infrared rays, particularly near-infrared rays, is excellent.

By including the infrared sensor cover and the infrared sensor body of the present invention, it can be suitably used in infrared sensor modules and cameras, and since the infrared sensor cover has particularly excellent near-infrared transmittance, it can be particularly suitably used in near-infrared cameras. The infrared sensor modules and cameras can be used in distance and image sensors used in autonomous driving and motion sensors, biometric authentication systems, biometric monitoring systems, security systems, etc.

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

(Transmittance measurement)
The transmittance of the infrared sensor covers obtained in the Examples and Comparative Examples was measured at wavelengths of 850 nm and 950 nm using a spectrophotometer (model name "U-4000", manufactured by Hitachi, Ltd.).

[Manufacturing Example 1] Manufacturing of a mold An aluminum ingot with a purity of 99.99% was cut into a cylindrical aluminum substrate having no rolling marks, with an outer diameter of 200 mm, an inner diameter of 155 mm, and a length of 350 mm. The aluminum substrate was subjected to a cloth polishing treatment and then electrolytically polished in a mixed solution of perchloric acid/ethanol (volume ratio = 1/4) to obtain a mirror finish.
The obtained aluminum substrate was anodized for 10 minutes in a 0.3 M aqueous oxalic acid solution under conditions of a direct current of 40 V and a temperature of 16° C. Thereafter, the aluminum substrate was immersed in a mixed aqueous solution of 6 mass % phosphoric acid/1.8 mass % chromic acid to remove the oxide film.
The obtained aluminum substrate was anodized in a 0.3 M aqueous oxalic acid solution under conditions of DC 40 V and temperature 16° C. for 30 seconds.
The aluminum base material on which the oxide film was formed was immersed in a 5% by mass phosphoric acid aqueous solution at 30° C. for 8 minutes to perform a pore size enlargement treatment (pore size enlargement treatment step). The aluminum base material was then anodized in a 0.3 M oxalic acid aqueous solution at a direct current of 40 V and a temperature of 16° C. for 30 seconds (oxide film growth step). This pore size enlargement treatment step and oxide film growth step were repeated a total of four times, and finally the pore size enlargement treatment step was performed to obtain a roll-shaped mold on the surface of which anodized alumina was formed, which had approximately conical pores with an average spacing of 100 nm and a depth of 200 nm.

[Production Example 2] Preparation of active energy ray curable composition 25 parts by mass of dipentaerythritol hexaacrylate, 25 parts by mass of pentaerythritol triacrylate, 25 parts by mass of polyethylene glycol diacrylate, and 25 parts by mass of an ethylene oxide modified compound of dipentaerythritol hexaacrylate were mixed, and further, 1 part by mass of a first photopolymerization initiator (trade name "Irgacure 184", manufactured by BASF Corporation), 0.5 parts by mass of a second photopolymerization initiator (trade name "Irgacure 819", manufactured by BASF Corporation), and 0.1 parts by mass of a release agent (trade name "TDP-2", manufactured by Nikko Chemicals Co., Ltd.) were added and mixed to prepare an active energy ray curable composition.

[Production Example 3] Production of an antireflection layer containing a moth-eye structure The roll-shaped mold obtained in Production Example 1 was rotated, and a polyethylene terephthalate substrate (product name "Cosmoshine A4300", manufactured by Toyobo Co., Ltd., thickness 75 μm) was run along the outer circumferential surface of the mold in the rotation direction of the mold, while the active energy ray-curable composition obtained in Production Example 2 was supplied between the outer circumferential surface of the mold and the running substrate, and the active energy ray-curable composition was cured by irradiating with ultraviolet rays. The obtained cured product was peeled off from the mold to produce an antireflection layer containing a moth-eye structure.
[Production Example 4] Production of an antireflection layer containing a moth-eye structure The roll-shaped mold obtained in Production Example 1 was rotated, and a triacetyl cellulose substrate (product name "TD80ULM", manufactured by FUJIFILM Corporation, thickness 80 μm) was run along the outer circumferential surface of the mold in the rotation direction of the mold, while the active energy ray-curable composition obtained in Production Example 2 was supplied between the outer circumferential surface of the mold and the running substrate, and the active energy ray-curable composition was cured by irradiating with ultraviolet rays. The obtained cured product was peeled off from the mold to produce an antireflection layer containing a moth-eye structure.

[Example 1]
An antireflection film having an antireflection layer including a multilayer structure (product name "FHC-ARAF", manufactured by Higashiyama Film Co., Ltd.) was attached to one side of a glass substrate (product name "S9112", manufactured by Matsunami Glass Industry Co., Ltd.) via an adhesive layer to obtain an infrared sensor cover.
The evaluation results obtained are shown in Table 1.

[Example 2]
The antireflection layer including the moth-eye structure obtained in Production Example 3 was attached to one surface of a glass substrate (product name "S9112", manufactured by Matsunami Glass Industry Co., Ltd.) via an adhesive layer to obtain an infrared sensor cover.
The evaluation results obtained are shown in Table 1.

[Example 3]
An antireflection film having an antireflection layer including a multilayer structure (product name "FHC-ARAF", manufactured by Higashiyama Film Co., Ltd.) was attached to one surface of a glass substrate (product name "S9112", manufactured by Matsunami Glass Industry Co., Ltd.) via an adhesive layer, and the antireflection layer including the moth-eye structure obtained in Production Example 3 was attached to the other surface of the glass substrate via an adhesive layer to obtain an infrared sensor cover.
The evaluation results obtained are shown in Table 1.
[Example 4]
The antireflection layer including the moth-eye structure obtained in Production Example 4 was attached to one surface of a glass substrate (product name "S9112", manufactured by Matsunami Glass Industry Co., Ltd.) via an adhesive layer to obtain an infrared sensor cover.
The evaluation results obtained are shown in Table 1.

[Comparative Example 1]
No anti-reflection layer was provided on either surface, and the glass substrate (product name "S9112", manufactured by Matsunami Glass Industry Co., Ltd.) itself served as the infrared sensor cover.
The evaluation results obtained are shown in Table 1.

As can be seen from Table 1, the infrared sensor covers obtained in the examples were excellent in infrared transmittance, particularly in near-infrared transmittance.
On the other hand, the infrared sensor covers obtained in the comparative examples were poor in infrared transmittance, particularly in near-infrared transmittance.

REFERENCE SIGNS LIST 10 Infrared sensor cover 20 Substrate 30 Antireflection layer including multilayer structure 31 High refractive index layer 32 Low refractive index layer 40 Antireflection layer including moth-eye structure 41 Base material 42 Moth-eye structure layer

Claims (8)

A near-infrared sensor cover, comprising: an anti-reflection layer including a multilayer structure on one surface of a substrate; and an anti-reflection layer including a moth-eye structure on the other surface of the substrate,
a near-infrared sensor cover in which an average distance between adjacent convex portions of the moth-eye structure is 20 nm to 400 nm, an average height of the convex portions is 60 nm to 400 nm, an aspect ratio which is a ratio of the average height of the convex portions to the average distance between the convex portions is 0.8 to 5.0, and a transmittance at a wavelength of 950 nm is 97 % or more. The near-infrared sensor cover according to claim 1, wherein the material of the substrate is glass or resin. The near-infrared sensor cover according to claim 2, wherein the material of the substrate is glass. The near-infrared sensor cover according to any one of claims 1 to 3, wherein the anti-reflection layer including the moth-eye structure has a substrate and a moth-eye structure, and the substrate is made of an acrylic resin, a polycarbonate resin, a polyester resin, or a cellulose resin. The near-infrared sensor cover according to any one of claims 1 to 4, wherein the multilayer structure includes multiple layers with different refractive indices. The near-infrared sensor cover according to any one of claims 1 to 5, having a transmittance of 97% or more at a wavelength of 850 nm. A near-infrared sensor module comprising the near-infrared sensor cover and the near-infrared sensor body according to any one of claims 1 to 6. A camera comprising a near-infrared sensor cover and a near-infrared sensor body according to any one of claims 1 to 6.