Distance measuring devices, electronic devices and mobile devices containing such distance measuring devices, and anti-reflective coatings.

Abstract

The invention relates to a distance measuring device 1 capable of achieving high accuracy in measurement. The distance measuring device 1 contains a LiDAR sensor 7 in a partitioned chamber 5 within an external part 2. The LiDAR sensor 7 contains a light-emitting element 71 for emitting a detection light L1 for measuring the distance to an object, a light-receiving element 73 for outputting a light-receiving signal S1 according to the amount of incident light, and an obfuscation element 3 for obfusing the light-emitting element 71 and the light-receiving element 73. Anti-reflective films 9a and 9b are provided on at least one side of the principal surface of the obfuscation element 3. The anti-reflective films 9a and 9b are configured by a film of thickness equal to or greater than 2µm and equal to or less than 40µm made of a liquid composition of a specific composition by spray coating.

Description

distance measuring device

[0001] The present invention relates to a distance measuring device that can be mounted on an electronic device or a mobile object.

[0002] As an example of a distance sensor mounted on a vehicle, which is an example of a moving body, a LiDAR (Light Detection and Ranging, Laser Imaging Detection and Ranging) sensor unit is known (Patent Document 1). This LiDAR sensor unit detects the distance to an object that has generated reflected light based on the time of flight of light from when detection light is emitted until the reflected light is received, known as ToF (Time of Flight).

[0003] Japanese Patent Application Laid-Open No. 2018-49014

[0004] However, in the above-described conventional LiDAR sensor unit, first, when the detection light emitted from the light-emitting element passes through the translucent cover, the light may be reflected inward (into the unit) by the inner or outer surface of the translucent cover. When this reflected light enters the light-receiving element and a light-receiving signal based on the reflected light is output from the light-receiving element, the presence of an object is recognized at the position of the inner or outer surface of the translucent cover, resulting in a decrease in the accuracy of measuring the distance to the actual object. Second, when the reflected light from the object passes through the translucent cover, the light may be reflected outward (outside the unit) by the inner or outer surface. The occurrence of this reflected light leads to a decrease in the amount of reflected light entering the light-receiving element, and in this case as well, there is a risk of a decrease in the accuracy of measuring the distance to the object.

[0005] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a distance measuring device that can achieve high measurement accuracy.

[0006] As a result of extensive research, the present inventors have found that a light-transmitting cover that covers the light-emitting element and light-receiving element of a distance measuring device is effective in improving measurement accuracy by satisfying the following requirements: - A liquid composition of a specific composition is used, which contains roughness-forming particles at a specific ratio, the roughness-forming particles including large and small inorganic particles having a specific particle size range in a specific mass ratio range; - An anti-reflection film of a specific thickness is formed on at least one main surface by spray coating using the liquid composition of the specific composition. Based on these new findings, the present inventors have completed the invention provided below and solved the above-mentioned problems.

[0007] In the following description, the components are (A) a resin component, (B) roughness-forming particles, (B1) inorganic small particles having a particle diameter (d1) of 0.05 μm or more and 0.4 μm or less, (B2) inorganic large particles having a particle diameter (d2) of 2 μm or more and 6 μm or less, and (C) a dilution solvent.

[0008] According to the present invention, there is provided a distance measuring device having a light-emitting element that emits detection light for measuring the distance to an object, a light-receiving element that outputs a light-receiving signal according to the amount of incident light, and a light-transmitting cover that covers the light-emitting element and the light-receiving element, wherein the light-transmitting cover has an anti-reflection film on at least one main surface side, and the anti-reflection film is a film formed by spray coating from a liquid composition and has a thickness of 2 μm or more and 40 μm or less, the liquid composition contains at least (A), (B), and (C), (B) is contained in an amount of 20% by mass or more and 60% by mass or less based on a total amount of 100% by mass of all solids of the composition, and (B) contains 90% by mass or more of (B1) and (B2), and the mass ratio of (B2) to (B1):1 is 1.8 or more and 3.3 or less.

[0009] The light-emitting element and light-receiving element, which are components of the distance measuring device, may be part of at least one selected from the group consisting of a LiDAR sensor unit, a ToF camera unit, and a millimeter-wave radar unit.

[0010] According to the present invention, there is provided an electronic device or a mobile object including the distance measuring device.

[0011] Examples of electronic devices include smartphones, tablet terminals, mobile phones, personal computers, game consoles, television sets, wearable terminals, digital still cameras, digital video cameras, etc. Examples of mobile objects include vehicles (automobiles, electric vehicles, hybrid electric vehicles, motorcycles, bicycles, personal mobility vehicles, etc.), aircraft (including drones), ships, robots, etc.

[0012] According to the present invention, there is provided an anti-reflection film formed on at least a light-transmitting cover of a distance measuring device having a light-emitting element that emits detection light for measuring the distance to an object and a light-receiving element that outputs a light-receiving signal according to the amount of incident light, the anti-reflection film comprising a film having a thickness of 2 μm or more and 40 μm or less that is formed by spray coating from a liquid composition, the liquid composition comprising at least (A), (B), and (C), (B) being contained in an amount of 20% by mass or more and 60% by mass or less based on 100% by mass of the total solid content of the composition, (B) comprising 90% by mass or more of (B1) and (B2), and the mass ratio of (B2) to (B1):1 is 1.8 or more and 3.3 or less.

[0013] The anti-reflection coating of the present invention may be formed on the light-transmitting cover of the distance measuring device, or may be formed on other components, examples of which will be described later.

[0014] The above liquid composition may include the following aspects. (B2) preferably contains silica. The silica preferably contains composite silica that has been blackened with a colorant. (B1) preferably contains carbon black. The viscosity at 25°C is preferably 1 mPa·s or more and 30 mPa·s or less.

[0015] The anti-reflection film may include the following aspects. It is preferable that the outermost surface on which the film is formed has a glossiness (hereinafter also referred to simply as "85° glossiness") for incident light at an incident angle of 85° of less than 4%, a reflectance (hereinafter also referred to simply as "reflectance") for light in the near-infrared region (wavelength 905 nm) of 6% or less, and an optical density of 1.5 or more. It is preferable that the outermost surface on which the film is formed has a maximum height Rz (hereinafter also referred to simply as "Rz") according to JIS B0601:2001 of 7 μm or more, an average Rsm (hereinafter also referred to simply as "Rsm") of the length of the profile curve elements of 80 μm or more, a profile skewness Rsk (hereinafter also referred to simply as "Rsk") of 0.3 or less, and a profile kurtosis Rku (hereinafter also referred to simply as "Rku") of 3 or more.

[0016] According to the present invention, a distance measuring device (such as a LiDAR sensor unit, a ToF camera unit, or a millimeter-wave radar unit) is provided that can achieve high measurement accuracy.

[0017] It is a cross-sectional view showing an application example of a distance measuring device according to one embodiment of the present invention. It is a diagram showing a configuration example of a LiDAR sensor unit used in the distance measuring device of Fig. 1. It is a diagram showing the configuration and operation of the LiDAR sensor unit of Fig. 2. It is a block diagram showing a configuration example of an electronic device according to one embodiment of the present invention.

[0018] The best mode for carrying out the present invention will be described below, but the present invention is not limited to the following embodiments. Appropriate modifications and improvements to the following embodiments based on the ordinary knowledge of those skilled in the art are also within the scope of the present invention, as long as they do not deviate from the spirit of the present invention.

[0019] In the numerical ranges described in this specification, the upper or lower limit value described in a certain numerical range may be replaced with a value shown in the Examples. In this specification, the content or amount of each component in a composition means the total content or amount of the multiple substances present in the composition, unless otherwise specified, when multiple substances corresponding to each component are present in the composition.

[0020] 1 shows an example of a distance measuring device 1 according to an embodiment of the present invention, which is disposed at the front left of a vehicle (left of the center in the left-right direction and forward of the center in the front-rear direction of the vehicle). The distance measuring device 1 has an exterior member 2, which defines an accommodation chamber 5 therein.

[0021] A LiDAR sensor unit 7 is disposed in the storage chamber 5. The LiDAR is a sensor that measures scattered light in response to pulsed laser irradiation to measure the distance to a target at a long distance.

[0022] 2 and 3 , the LiDAR sensor unit 7 includes a light-emitting element 71 and a light-receiving element 73 housed inside a housing 75, and a light-transmitting cover 3 serving as a window that closes an opening 75a of the housing 75. In this example, the light-transmitting cover 3 does not form part of the exterior surface of the vehicle, but this is not limited to this.

[0023] The light-transmitting cover 3 is, for example, a plate-like member made of glass or resin, and is attached, for example, with an adhesive or the like, to an opening end surface 75b of the housing 75 so as to close the opening 75a of the housing 75 and, as a result, cover the light-emitting element 71 and the light-receiving element 73. The light-transmitting cover 3 has optical properties that allow at least the majority (e.g., 99% or more) of the light in the wavelength band (e.g., near-infrared region) of the detection light L1 emitted by the light-emitting element 71 to transmit.

[0024] Examples of resins forming the base material of the translucent cover 3 include heat-resistant resins such as polycarbonate (PC) resins, polyamide (PA) resins, liquid crystal polymers (LCPs), and polyacetal (POM) resins. The base material of the translucent cover 3 may contain a pigment. The pigments that may be contained are not particularly limited, and as with (B1) and (B2) described below, either resin particles or inorganic particles can be used. Examples of resin particles include melamine resin, benzoguanamine resin, benzoguanamine / melamine / formalin condensate, acrylic resin, urethane resin, styrene resin, fluororesin, and silicone resin. Examples of inorganic particles include silica, alumina, calcium carbonate, barium sulfate, titanium oxide, magnetite black, copper-iron-manganese black, titanium black, carbon black, and aniline black. These pigments may be used alone or in combination of two or more. When a pigment is contained in the base material of the light-transmitting cover 3, the content of the pigment can be appropriately set depending on the required performance, etc., and is not particularly limited. For example, the content of the pigment is about 0.3% by mass or more, preferably 0.4% by mass or more, and for example, 15% by mass or less, preferably 12% by mass or less, relative to the base material.

[0025] The light-emitting element 71 is configured to emit detection light L1 toward the outside of the vehicle. Near-infrared light with a wavelength of 905 nm, for example, may be used as the detection light L1. The light-emitting element 71 may be a semiconductor light-emitting element such as a laser diode or a light-emitting diode.

[0026] The LiDAR sensor unit 7 may be equipped with an optical system (not shown) for irradiating the detection light L1 in a desired direction, and a scanning mechanism (not shown) for changing the irradiation direction of the detection light L1 to scan the detection area.

[0027] The light receiving element 73 is configured to output a light receiving signal S1 corresponding to the amount of incident light. A photodiode, a phototransistor, a photoresistor, or the like may be used as the light receiving element 73. The LiDAR sensor unit 7 may include an amplifier circuit (not shown) for amplifying the light receiving signal S1.

[0028] A processor (controller) 8 is disposed within the accommodation chamber 5 (FIG. 1). The processor 8 may be built into the housing 75 of the LiDAR sensor unit 7. The processor 8 outputs a control signal S0 that causes the light-emitting element 71 to emit detection light L1 at a desired timing. The processor 8 receives a light-receiving signal S1 output from the light-receiving element 73.

[0029] The processor 8 calculates the distance to the object 200 that generated the reflected light L2 based on the time from when the detection light L1 is emitted from the light-emitting element 71 until the reflected light L2 is incident on the light-receiving element 73.

[0030] A lamp unit 6 is also arranged in the accommodation chamber 5 along with the LiDAR sensor unit 7. The lamp unit 6 is a device that emits visible light outside the vehicle. Examples of the lamp unit 6 include a headlight unit, a sidelight unit, a turn signal unit, and a fog light unit. The lamp unit 6 is generally arranged at the four corners of the vehicle. The four corners are also locations where there are fewer obstacles when detecting information outside the vehicle. By arranging the LiDAR sensor unit 7 so that it shares the accommodation chamber 5 with the lamp unit 6, information outside the vehicle can be detected efficiently.

[0031] The LiDAR sensor unit 7 may be replaced with an appropriate sensor unit that can be used to measure the distance to an object 200 located outside the vehicle. Examples of such a sensor unit include a Time of Flight (ToF) camera unit and a millimeter-wave radar unit. Configurations that use multiple measurement methods may be built into a single sensor unit. The wavelength of the detection light L1 emitted by the light-emitting element 71 and the wavelength to which the light-receiving element 73 is sensitive may be determined appropriately depending on the measurement method used.

[0032] (Anti-Reflection Film) An anti-reflection film 9 is provided on part or all of at least one main surface of the translucent cover 3. The "main surface" includes the outer surface (hereinafter simply referred to as the "front surface") and the inner surface (hereinafter simply referred to as the "rear surface") of the translucent cover 3. The "main surface" includes a form in which the anti-reflection film 9 is formed directly on at least one main surface (front surface, rear surface, or both front and rear surfaces) of the translucent cover 3, as well as a form in which an optional layer (e.g., a primer layer) is interposed between the translucent cover 3 and the anti-reflection film 9. The "part or all" includes a case in which the anti-reflection film 9 is formed on a part of at least one main surface of the translucent cover 3. In this case, the mirror-like surface of the plate-like substrate is exposed on at least one main surface of the translucent cover 3. The anti-reflection film 9 may be provided on at least one main surface of the translucent cover 3 as well as on the end surface (inner end surface, outer end surface, or both inner and outer end surfaces). 3 illustrates a case in which anti-reflection films 9a, 9b are formed directly on the entire surfaces of both main surfaces (front and back surfaces) of the light-transmitting cover 3. The anti-reflection film 9a is formed on the entire surface of the back surface (inner surface) 3a of the light-transmitting cover 3, and the anti-reflection film 9b is formed on the entire surface of the front surface (outer surface) 3b of the light-transmitting cover 3.

[0033] The role of the anti-reflection films 9 (9a, 9b) is as follows: When the detection light L1 emitted from the light-emitting element 71 passes through the light-transmitting cover 3, light L3 is reflected inward by the rear surface 3a of the light-transmitting cover 3. When the reflected light L3 is incident on the light-receiving element 73 and a light-receiving signal S1 based on the reflected light L3 is output from the light-receiving element 73, the processor 8 may recognize that an object is present at the rear surface 3a of the light-transmitting cover 3. Furthermore, when reflected light L2 from the object 200 passes through the light-transmitting cover 3, light L4 is reflected outward by the rear surface 3a of the light-transmitting cover 3. The generation of reflected light L4 leads to a decrease in the amount of reflected light L2 incident on the light-receiving element 73.

[0034] First, the anti-reflection film 9a suppresses the generation of reflected light L3. Therefore, it is possible to reduce the possibility that the reflected light L3 will be incident on the light receiving element 73. Alternatively, it is possible to reduce the amount of reflected light L3 that is incident on the light receiving element 73. This reduces the influence of reflected light L3 on the measurement of the distance to the object 200 by the LiDAR sensor unit 7. Second, the anti-reflection film 9a suppresses the generation of reflected light L4. Therefore, it is possible to suppress a decrease in the amount of reflected light L2 that is incident on the light receiving element 73. This suppresses a decrease in the level of the light receiving signal S1 associated with the object 200.

[0035] When the detection light L1 emitted from the light-emitting element 71 passes through the light-transmitting cover 3, light L5 is reflected inward by the surface 3b of the light-transmitting cover 3. When the reflected light L5 is incident on the light-receiving element 73 and a light-receiving signal S1 based on the reflected light L5 is output from the light-receiving element 73, the processor 8 may recognize that an object is present at the position of the surface 3b of the light-transmitting cover 3. Furthermore, when the reflected light L2 from the object 200 passes through the light-transmitting cover 3, light L6 is reflected outward by the surface 3b of the light-transmitting cover 3. The generation of reflected light L6 leads to a decrease in the amount of reflected light L2 incident on the light-receiving element 73.

[0036] First, the anti-reflection film 9b suppresses the generation of reflected light L5. Therefore, it is possible to reduce the possibility that the reflected light L5 will be incident on the light receiving element 73. Alternatively, it is possible to reduce the amount of reflected light L5 that is incident on the light receiving element 73. This reduces the influence of reflected light L5 on the measurement of the distance to the object 200 by the LiDAR sensor unit 7. Second, the anti-reflection film 9b suppresses the generation of reflected light L6. Therefore, it is possible to suppress a decrease in the amount of reflected light L2 that is incident on the light receiving element 73. This suppresses a decrease in the level of the light receiving signal S1 associated with the object 200.

[0037] According to the distance measuring device 1 of the embodiment of the present invention, the influence on distance measurement of inward reflection by the rear surface 3 a and the front surface 3 b of the light-transmitting cover 3 is suppressed, and the decrease in the amount of light incident on the light-receiving element 73 due to outward reflection by the rear surface 3 a and the front surface 3 b of the light-transmitting cover 3 is suppressed, thereby improving the detection accuracy of the distance measuring device 1. In other words, high measurement accuracy is realized.

[0038] The anti-reflection coating 9 (9a, 9b) in this example is composed of a film formed from a liquid composition.

[0039] <Liquid Composition> A liquid composition according to one embodiment (hereinafter also simply referred to as the "composition") is used to form a film on at least one main surface of a light-transmitting cover 3 (hereinafter also simply referred to as the "substrate"), and further on its end surface, and includes (A) a resin component, (B) roughness-forming particles, and (C) a dilution solvent. (B) used to form the composition includes (B1) small particles having a particle diameter (d1) of 0.05 μm or more and 0.4 μm or less, and (B2) large particles having a particle diameter (d2) of 2 μm or more and 6 μm or less, and may include components other than (B1) and (B2). That is, a composition according to one embodiment includes (A), (B1), (B2), and (C). The composition according to one embodiment can be suitably applied to the surface of the substrate by spray coating.

[0040] -(A)- (A) used to form the composition serves as a binder for (B). The material for (A) is not particularly limited, and either a thermoplastic resin or a thermosetting resin can be used. Examples of thermosetting resins include acrylic resins, urethane resins, phenolic resins, melamine resins, urea resins, diallyl phthalate resins, unsaturated polyester resins, epoxy resins, and alkyd resins. Examples of thermoplastic resins include polyacrylic ester resins, polyvinyl chloride resins, butyral resins, and styrene-butadiene copolymer resins. From the viewpoints of the heat resistance, moisture resistance, solvent resistance, and surface hardness of the formed uneven film, it is preferable to use a thermosetting resin as (A). As the thermosetting resin, acrylic resins are particularly preferable, taking into consideration the flexibility and toughness of the formed film. One type of (A) may be used alone, or two or more types may be used in combination. The content (total amount) of (A) is not particularly limited, but taking into consideration the blending balance with other components, it is preferably 5% by mass or more, more preferably 15% by mass or more, even more preferably 25% by mass or more, and preferably 50% by mass or less, more preferably 45% by mass or less, and even more preferably 40% by mass or less, relative to the total amount (100% by mass) of all solid contents of the composition.

[0041] -(B)- It is essential that (B) used to form the composition is a combination of a plurality of roughness-forming particles of different sizes, and (B) is particularly a combination of (B1) small particles and (B2) large particles. For example, when (B) is composed of only two types of roughness-forming particles of different sizes (i.e., (B1) and (B2)), the particle diameter (d2) of (B2) is preferably 10 times or more, more preferably 15 times or more, and preferably 40 times or less, and more preferably 35 times or less the particle diameter (d1) of (B1). When three or more types of roughness-forming particles of different sizes are used as (B), the particle diameter (d1) of the roughness-forming particle with the largest particle diameter is max ) and the particle diameter (d min ) and the above relationship (i.e., (d max ) is (d min ) is preferably 10 times or more, more preferably 15 times or more, and preferably 40 times or less, more preferably 35 times or less.

[0042] In one embodiment, (d1) is preferably 0.05 μm or more, more preferably 0.1 μm or more, and preferably 0.4 μm or less, more preferably 0.3 μm or less. (d2) is preferably 2 μm or more, more preferably 3 μm or more, and preferably 6 μm or less, more preferably 5 μm or less, and even more preferably 4 μm or less. The particle size (d1) of (B1) and the particle size (d2) of (B2) are volume-based median sizes measured with a laser diffraction / scattering particle size distribution analyzer.

[0043] In one embodiment, the mass ratio of (B2) in (B) is preferably more than 1.62, more preferably 1.8 or more, preferably less than 3.58, and more preferably 3.3 or less, relative to (B1): 1. The present inventors have found that by using a combination of (B1) and (B2) having the above-mentioned specific particle size ranges in this mass ratio range, one (B1) is more likely to be embedded between two adjacent (B2) particles in the formed film, and as a result, low gloss and low reflectivity can be achieved on the film surface.

[0044] The combined content (total amount) of (B1) and (B2) in (B) is preferably 90% by mass or more, more preferably 95% by mass or more. The upper limit is not particularly limited, and is 100% by mass. That is, in one embodiment, (B1) and (B2) may be contained in an amount of preferably 90% by mass or more in 100% by mass of (B).

[0045] The content (total amount) of (B) is preferably 20% by mass or more, more preferably 25% by mass or more, even more preferably 30% by mass or more, and is preferably 60% by mass or less, more preferably 50% by mass or less, even more preferably 45% by mass or less, and particularly preferably 40% by mass or less, relative to the total amount (100% by mass) of all solids in the composition. If the total amount of (B) is less than 20% by mass, problems such as increased gloss and insufficient optical density will occur, and if it exceeds 60% by mass, the amount of (A) in the formed coating film will be relatively small, which may result in problems such as the coating film peeling off from the coated object.

[0046] As (B2), either resin particles or inorganic particles can be used. Examples of resin particles include melamine resin, benzoguanamine resin, benzoguanamine / melamine / formalin condensate, acrylic resin, urethane resin, styrene resin, fluororesin, and silicone resin. On the other hand, examples of inorganic particles include silica, alumina, calcium carbonate, barium sulfate, titanium oxide, and carbon. These may be used alone or in combination of two or more.

[0047] To obtain better properties, it is preferable to use inorganic particles as (B2). By using inorganic particles as (B2), it is easier to form a film with lower gloss and higher light-shielding properties. Silica is preferred as the inorganic particles used as (B2). The shape of (B2) is not particularly limited, but to achieve a low gloss, low reflectance, and low L value on the surface of the formed film, it is preferable to use particles (sharp products) with a narrow particle size distribution (CV (Coefficient of Variation) value, for example, 15 or less). The CV value is a numerical representation of the degree of particle size distribution spread (particle size variation) relative to the average particle size (arithmetic mean particle size). The use of such particles increases the contact opportunity between (B2) and (B1) in the formed film, making it easier to achieve a low gloss, low reflectance, and low L value on the surface of the formed film. Furthermore, to further reduce the gloss of the formed film surface, it is preferable to use irregularly shaped particles as (B2). Among these, it is particularly preferable to use porous, amorphous silica particles as (B2).By using such particles as (B2), when a film is formed, light is repeatedly refracted on the surface and inside of (B2), which can further reduce the gloss of the film surface.

[0048] In one embodiment, (B2) can be colored black with an organic or inorganic colorant to suppress light reflection on the surface of the film to be formed. Examples of such materials include composite silica, conductive silica, and black silica. Examples of composite silica include a composite of carbon black (hereinafter simply referred to as "CB") and silica synthesized at the nano level. Examples of conductive silica include silica particles coated with conductive particles such as CB. Examples of black silica include natural silica ores containing graphite in silica rock.

[0049] On the other hand, like (B2), the material of (B1) is not particularly limited, and either resin particles or inorganic particles can be used. Examples of resin particles include melamine resin, benzoguanamine resin, benzoguanamine / melamine / formalin condensate, acrylic resin, urethane resin, styrene resin, fluororesin, and silicone resin. On the other hand, examples of inorganic particles include silica, alumina, calcium carbonate, barium sulfate, titanium oxide, and CB. These may be used alone or in combination of two or more.

[0050] As (B1), for example, CB, which is added as a coloring / conductive agent, can be used. By using CB as (B1), the formed film is colored, thereby further improving the antireflection effect and obtaining a good antistatic effect.

[0051] -(C)- (C) used in forming the composition is blended for the purposes of dissolving (A) and adjusting the viscosity of the entire composition. The use of (C) facilitates the mixing of (A) and other components added as needed, improving the uniformity of the composition. Furthermore, it is possible to appropriately adjust the viscosity of the composition, which improves the ease of handling the composition and the uniformity of the coating thickness when forming a film on the surface of a substrate.

[0052] (C) is not particularly limited as long as it is a solvent that can dissolve (A), and examples thereof include organic solvents and water. Examples of organic solvents that can be used include methyl ethyl ketone, toluene, propylene glycol monomethyl ether acetate, ethyl acetate, butyl acetate, methanol, ethanol, isopropyl alcohol, and butanol. (C) may be used alone or in combination of two or more.

[0053] In order to obtain the effects of blending (C) as described above, the content (total amount) of (C) in the composition is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and preferably 20 parts by mass or less, per 100 parts by mass of (A).

[0054] —(D) Optional Component— In addition to the above components ((A), (B), and (C)), the composition may contain (D) to the extent that the effects of the present invention are not impaired. Examples of (D) include leveling agents, thickeners, pH adjusters, lubricants, dispersants, antifoaming agents, curing agents, and reaction catalysts.

[0055] In particular, when a thermosetting resin is used as (A), the incorporation of a curing agent can promote crosslinking of (A). Examples of curing agents include functional group-containing urea compounds, melamine compounds, isocyanate compounds, epoxy compounds, aziridine compounds, and oxazoline compounds. Among these, isocyanate compounds are preferred as curing agents. A single curing agent may be used alone, or two or more may be used in combination. When the curing agent is incorporated into the composition, the content is preferably 10 to 80 parts by mass per 100 parts by mass of (A). Adding the curing agent within this range increases the hardness of the formed film. As a result, even when the film is placed in an environment where it slides against other components, the film surface properties are maintained for a long period of time, and low gloss, high light blocking, low reflectance, and high blackness are easily maintained. When a curing agent is incorporated into the composition, a reaction catalyst can be used in combination to promote the reaction between (A) and the curing agent. Examples of reaction catalysts include ammonia and ammonium chloride. When the reaction catalyst is blended in the composition, the proportion thereof is preferably 0.1 parts by mass or more and 10 parts by mass or less per 100 parts by mass of the curing agent.

[0056] The composition according to one embodiment preferably has a viscosity at 25°C of 1 mPa·s or more, preferably 30 mPa·s or less, more preferably 20 mPa·s or less, so that the composition can be applied to the surface of the substrate using a spray (spray coating) while maintaining the smoothness of the composition. If the viscosity of the composition is too low, it may be impossible to form a film thick enough to sufficiently suppress the generation of reflected light L3, L4, L5, and L6. If the viscosity of the composition is too high, it may be difficult to uniformly spray the composition onto the surface of the substrate, and as a result, it may be impossible to form a film of uniform thickness and little performance variation. The viscosity varies depending on the components contained in the composition, i.e., the types and molecular weights of the (A) and (B) used. Furthermore, if (D) is blended in addition to the (A) and (B), it also varies depending on the type and molecular weight of (D). However, it can be easily adjusted by adjusting the amount of (C) in the composition within the above range.

[0057] The composition according to one embodiment of the present invention can be prepared (manufactured) by adding (A), (B), and, if necessary, (D) to (C), and mixing and stirring them. The order in which the components are mixed is not particularly limited, as long as these components are mixed uniformly.

[0058] The composition according to one embodiment of the present invention may be a one-component type or a two-component type. When a curing agent is blended as (D) in the composition, the composition according to one embodiment may be, for example, a two-component type having a first component containing components other than the curing agent and a second component containing the curing agent.

[0059] The method for forming the film is not particularly limited, and the film can be formed on the substrate by any method or device, such as spray coating (for example, air spray, airless spray, electrostatic spray, etc.), paint brush, curtain flow coating, roller brush coating, bar coating, kiss roll, metalling bar, gravure roll, reverse roll, dip coating, or die coating.

[0060] In particular, the composition according to one embodiment preferably forms a film by spray coating, which requires droplets to be sprayed from a small spray hole. In other words, the film formed from the liquid composition according to one embodiment is a spray-coated film. When spray coating is performed using the composition according to one embodiment, droplets of the composition are successively deposited on the surface of the substrate, and at the same time, the evaporation of (C) from the droplets deposited on the substrate progresses. As a result, solids (particles) from which (C) has been removed from the droplets are successively deposited on the surface of the substrate, forming a solid particle laminate. According to one embodiment, this solid particle laminate constitutes the film.

[0061] When using a thermosetting resin as (A) and a composition containing a curing agent as (D), it is preferable to adhere a solid particle laminate to the surface of the substrate and then heat the laminate to cure it. Even if a trace amount of (C) remains in the laminate before heating, the heating will almost completely volatilize (C). Heating conditions can be adjusted appropriately depending on the thickness of the laminate before heating, the heat resistance of the substrate, the type of (C) used, and other factors. For example, heating conditions are 70°C to 150°C for 1 minute to 10 minutes, preferably 100°C to 130°C for 2 minutes to 5 minutes.

[0062] The thickness of the anti-reflection films 9a, 9b is not particularly limited, as long as it provides good adhesion strength to the light-transmitting cover 3 and can suppress the generation of reflected light on the surface on which the film is formed. An example of a suitable film thickness is preferably 2 μm or more, more preferably 5 μm or more, and preferably 40 μm or less, more preferably 25 μm or less. The film thickness of the anti-reflection films 9a, 9b refers to the height including the portions of the film (B2) and (B1) protruding from the surface of the substrate. The film thickness can be measured by a method conforming to JIS K7130.

[0063] <Film Properties> The properties of a film formed from a composition according to one embodiment are as follows.

[0064] (Glossiness, Reflectance, Optical Density, L Value, Adhesion) A film formed from a composition according to one embodiment preferably has an 85° glossiness of less than 4%, a reflectance of 6% or less, and an optical density of 1.5 or more.

[0065] Here, if the film formed from the composition according to one embodiment is exposed on the outermost surface, it is preferable that the 85° gloss, reflectance, and optical density of the film surface are literally within the above ranges. If another film is coated on the film formed from the composition according to one embodiment, it is preferable that the 85° gloss, reflectance, and optical density of the surface of the other film (i.e., the outermost surface of the light-transmitting cover 3) are within the above ranges. Hereinafter, these surfaces are collectively referred to as the "outermost surface of the film."

[0066] The film formed from the composition according to one embodiment preferably has an 85° gloss of less than 4%, a reflectance of 6% or less, and an optical density of 1.5 or more on the outermost surface of the film. When the 85° gloss, reflectance, and optical density of the outermost surface of the film are within the above ranges, low gloss, low reflectance (excellent antireflection properties; the same applies hereinafter), and high light-blocking properties can be achieved on the outermost surface of the film.

[0067] The upper limit of the 85° gloss is more preferably less than 3.5%, and even more preferably less than 2.5%. By adjusting the 85° gloss within the above range, the advantage of suppressing light reflection is easily obtained. The lower limit of the 85° gloss is not particularly limited, and the lower the better.

[0068] The upper limit of the reflectance is more preferably 3% or less, and even more preferably 2.5% or less. The lower limit of the reflectance is not particularly limited, and the lower the better. By adjusting the reflectance within the above range, the advantage of preventing malfunction of the sensor can be enjoyed.

[0069] The lower limit of the optical density is more preferably 1.8 or more, and even more preferably 2.0 or more. By adjusting the optical density within the above range, the light-blocking property can be further improved. The upper limit of the optical density is not particularly limited, and the higher the better, but it is, for example, less than 3.0.

[0070] In addition to the above, the film formed from the composition according to one embodiment preferably has an L value of 22 or less on the outermost surface of the film. The upper limit of the L value (blackness) is more preferably 20 or less, and even more preferably 18 or less. The lower limit of the L value is not particularly limited. The L value refers to the lightness L* value of the outermost surface of the film in the CIE 1976 L*a*b* (CIELAB) color system according to the SCE method. The SCE method refers to a specular reflection removal method, which means a method of measuring color by removing specular reflection. The definition of the SCE method is specified in JIS Z 8722 (2009). The SCE method removes specular reflection when measuring, resulting in colors closer to those actually seen by the human eye. CIE is an abbreviation for Commission Internationale de l'Eclairage, which stands for International Commission on Illumination. CIELAB color space is a uniform color space recommended in 1976 and specified in JIS Z 8781 (2013) to measure color differences due to differences in perception and devices. CIELAB's three coordinates are represented by the L*, a*, and b* values. The L* value indicates lightness and ranges from 0 to 100. An L* value of 0 indicates black, while an L* value of 100 indicates diffuse white. The a* value indicates a color between red and green. A negative a* value indicates a color leaning toward green, while a positive a* value indicates a color leaning toward red. The b* value indicates a color between yellow and blue. A negative b* value indicates a color leaning toward blue, while a positive b* value indicates a color leaning toward yellow.

[0071] The glossiness, reflectance, optical density, and L value can be measured by the methods described below.

[0072] In addition to the above properties (glossiness, reflectance, optical density, L value), it is preferable that the film formed from the composition further has good adhesion to the surface of the substrate, and the adhesion of the film formed from the composition to the surface of the substrate is preferably such that 75% or more of the coating remains, as shown in the adhesion evaluation in the Examples described later.

[0073] (Rz, Rsm, Rsk, Rku, Ra) In a film formed from a composition according to one embodiment, the maximum height Rz of the outermost surface of the film is preferably 7 μm or more, the average length Rsm of the contour curve elements is 80 μm or more, the contour curve skewness Rsk is 0.3 or less, and the contour curve kurtosis Rku is 3 or more. By having Rz, Rsm, Rsk, and Rku of the outermost surface of the film within the above ranges, the gloss, reflectance, and optical density of the outermost surface of the film can be within the above ranges (85° gloss less than 4%, reflectance 6% or less, optical density 1.5 or more), and as a result, low gloss, low reflectance, and high light-blocking properties of the outermost surface of the film can be achieved.

[0074] The lower limit of Rz is more preferably 10 μm or more. By setting the lower limit of Rz to the above value, it is easier to adjust the film to have even lower gloss, lower reflectance, and higher light-shielding properties. The upper limit of Rz is not particularly limited, but is preferably 50 μm or less, more preferably 30 μm or less. By setting the upper limit of Rz to the above value, it is easier to achieve even lower gloss, lower reflectance, and higher light-shielding properties on the outermost surface of the film.

[0075] Rsm represents the average length of the profile curve element relative to the reference length. The lower limit of Rsm is more preferably 100 μm or more, and even more preferably 120 μm or more. By setting the lower limit of Rsm to the above value, the benefit of even lower gloss is more likely to be obtained. The upper limit of Rsm is not particularly limited, but is preferably 160 μm or less. Within the above range, better adhesion can be obtained between the substrate and the film formed thereon.

[0076] Rsk represents the cube mean of the height Z(x) at a reference length that has been made dimensionless by the cube of the root mean square height (Zq), and is an index representing the deviation of the uneven shape of the outermost surface of the film relative to the mean line, i.e., the degree of distortion. If the Rsk value is positive (Rsk>0), the uneven shape tends to be biased toward the concave side, resulting in sharp protrusions, and if it is negative (Rsk<0), the uneven shape tends to be biased toward the convex side, resulting in dull protrusions. A dull protrusion of the profile curve results in lower haze than a sharp one. The upper limit of Rsk is more preferably 0.2 or less. By setting the upper limit of Rsk to the above value, the benefit of low gloss can be more easily obtained. The lower limit of Rsk is not particularly limited, but is preferably 0 or more. By setting the lower limit of Rsk to the above value, the benefit of low gloss can be more easily obtained.

[0077] Rku represents the fourth-mean value of the height Z(x) at a reference length dimensionlessized by the fourth power of the root mean square height (Zq), and is an index indicating the degree of sharpness of the tip of the unevenness on the outermost surface of the film. The larger Rku, the more the tips of the unevenness are sharp, so the inclination angle near the tip of the unevenness is larger, but the inclination angle of other parts is smaller, which weakens the strength of the tip part and tends to cause the disadvantage of the coating film falling off. Furthermore, the smaller Rku, the more the tips of the unevenness are flat, so the inclination angle of the tip of the unevenness is smaller, which tends to cause the disadvantage of increased 85° gloss. The lower limit of Rku is more preferably 3.3 or more. By setting the lower limit of Rku to the above value, the advantage of low gloss is more likely to be obtained. The upper limit of Rku is not particularly limited, but is preferably 5 or less. By setting the upper limit of Rku to the above value, the advantage of low gloss is more likely to be obtained.

[0078] The film formed from the composition according to one embodiment has an arithmetic mean roughness (Ra) of the outermost surface of the film of preferably 0.5 μm or more, more preferably 1.0 μm or more, and even more preferably 1.5 μm or more.

[0079] The Rz, Rsm, Rsk, Rku, and Ra of the outermost surface of the film can be measured and calculated based on JIS B0601:2001.

[0080] (Other Embodiments) In the above-described embodiment, the anti-reflection film 9 can be formed directly on at least one main surface of the light-transmitting cover 3 without any pre-treatment or via a pre-treatment layer, but is not limited to this. For example, an anti-reflection film sheet may be prepared by forming the anti-reflection film 9 on an extremely thin plastic film (such as a PET film) by spray coating, and the sheet may be cut to fit the shape of at least one main surface of the light-transmitting cover 3 to obtain a sheet piece. The sheet piece is then attached to at least one main surface of the light-transmitting cover 3 via an adhesive layer, and the anti-reflection film 9 may finally be formed.

[0081] The anti-reflection film 9 in the above embodiment is not limited to being formed on the light-transmitting cover 3, but may also be formed on other components of the distance measuring device 1 (for example, the exterior member 2 or the inner wall of the housing 75 of the LiDAR sensor unit 7). The material of the other components on which the anti-reflection film 9 can be formed is not limited to glass or resin, but may also be metal (for example, SUS or aluminum).

[0082] (Application Examples) The distance measuring device 1 according to the above embodiment may be realized as a device mounted on other moving bodies, such as vehicles other than four-wheeled vehicles (automobiles, electric vehicles, hybrid electric vehicles, etc.), such as motorcycles, bicycles, personal mobility vehicles, aircraft (including drones), ships, robots, etc. The distance measuring device 1 according to the above embodiment can also be mounted on various electronic devices, such as smartphones, tablet terminals, mobile phones, personal computers, game consoles, television sets, wearable terminals, digital still cameras, digital video cameras, etc. The following describes the case where the distance measuring device 1 is mounted on a smartphone, as an example.

[0083] 4, the smartphone 201 includes a ranging module 202, an imaging device 203, a display 204, a speaker 205, a microphone 206, a communication module 207, a sensor unit 208, a touch panel 209, and a control unit 210, which are connected via a bus 211. The control unit 210 has functions as an application processing unit 221 and an operation system processing unit 222 by the CPU executing a program.

[0084] 2 and 3 is applied to the ranging module 202. For example, the ranging module 202 is disposed on the front surface of the smartphone 201, and can measure the distance to the user of the smartphone 201 and output various information as the ranging result. The processor 8 in FIG. 3 corresponds to the control unit 210 in FIG. 4.

[0085] The imaging device 203 is arranged on the front side of the smartphone 201, and captures an image of the user of the smartphone 201 by capturing an image of the user as a subject. Note that the smartphone 201 may also have a configuration (not shown) in which the imaging device 203 is arranged on the back side of the smartphone 201.

[0086] The display 204 displays an operation screen for performing processing by the application processing unit 221 and the operation system processing unit 222, and images captured by the imaging device 203. The speaker 205 and the microphone 206 output the voice of the other party and pick up the voice of the user when making a call using the smartphone 201, for example.

[0087] The communication module 207 performs communication via a communication network. The sensor unit 208 senses speed, acceleration, proximity, etc., and the touch panel 209 acquires touch operations by the user on the operation screen displayed on the display 204.

[0088] The application processing unit 221 performs processing for providing various services via the smartphone 201. For example, the application processing unit 221 may perform processing for creating a computer graphics face that virtually reproduces the user's facial expression based on information supplied from the distance measurement module 202 and displaying the face on the display 204. Furthermore, the application processing unit 221 may perform processing for creating three-dimensional shape data of any three-dimensional object based on information supplied from the distance measurement module 202, for example.

[0089] The operation system processing unit 222 performs processing for realizing basic functions and operations of the smartphone 201. For example, the operation system processing unit 222 may perform processing to authenticate the user's face and unlock the smartphone 201 based on information supplied from the ranging module 202. The operation system processing unit 222 may perform processing to recognize user gestures based on information supplied from the ranging module 202, and to input various operations in accordance with the gestures.

[0090] The present invention will be specifically described below based on experimental examples (including examples and comparative examples), but the present invention is not limited to these experimental examples. In the following description, "parts" means "parts by mass" and "%" means "% by mass".

[0091] [Constituents of the Composition] The following was prepared as A (resin component): A1: Thermosetting acrylic resin (Acrydic A801, DIC Corporation, solid content 50%)

[0092] The following were prepared as B1 (small particles) belonging to B (roughness-forming particles): B1a: Carbon black (CB) (particle diameter 150 nm) (MHI Black #273, Mikuni Color Co., Ltd., CB content 9.5%) B1b: Transparent silica (particle diameter 58 nm) (ACEMATT R972, EVONIK)

[0093] The following were prepared as B2 (large particles) belonging to B: B2a: Composite silica (particle diameter 3 μm) (Vexia ID, Fuji Silysia Chemical Ltd.) B2b: Black acrylic beads (particle diameter 3 μm) (Labcolor 224 SMD Black, Dainichiseika Color & Chemicals Mfg. Co., Ltd.) B2c: Transparent silica (particle diameter 4.1 μm) (Sylysia 430, Fuji Silysia Chemical Ltd.) B2d: Transparent silica (particle diameter 8 μm) (Sylysia 450, Fuji Silysia Chemical Ltd.) B2e: Transparent acrylic beads (particle diameter 3 μm) (Unipowder NMB-0320C, ENEOS Corporation)

[0094] The Vexia ID used in B2a (composite silica) is a composite particle of CB and silica with a CB / silica ratio of approximately 25 / 75 (mass ratio). The MHI Black #273 used in B1a (CB) is a CB dispersion, with 9.5% of the total solid content of the dispersion (18%) being CB and the remaining 8.5% being other compounds. Of the 8.5% other compounds, 3% is a copper compound and 5.5% is an acrylic resin.

[0095] The following were prepared as optional components D: D1: Isocyanate compound (Takenate D110N, Mitsui Chemicals, solid content 75%)

[0096] [Substrate] A substrate for a sample for evaluation was prepared as a substrate for the sample for evaluation. The substrate for the sample for evaluation was a rectangular polycarbonate flat plate (length 100 mm, width 50 mm, thickness 1.5 mm) made of a black polycarbonate sheet material with both surfaces in the thickness (X) direction finished to a matte finish.

[0097] [Experimental Examples 1 to 17] 1. Preparation of Compositions Each component in each Experimental Example was added to a required amount of a mixed solvent (methyl ethyl ketone:butyl acetate=50:50) as a dilution solvent (C) so as to have the solid content ratio shown in Table 1, so as to give a total solid content of approximately 25% by mass, and the mixture was stirred and mixed to prepare a liquid composition (hereinafter also simply referred to as "liquid").

[0098] 2. Preparation of Evaluation Samples The liquid preparation obtained in each experimental example was sprayed onto one side of the substrate by spray coating using the same method as in (3-1) Coatability below, and then heated and dried at 120°C for 3 minutes to obtain an evaluation sample on the surface of the substrate, in which a post-heating coating film (hereinafter simply referred to as "coating film") of solid particle lamination formed by spray coating with an average film thickness of 20 μm was formed.

[0099] 3. Evaluation The liquid formulations obtained in each experimental example were evaluated for various properties (paintability) using the methods described below (liquid formulation evaluation). In addition, the coating films formed on the evaluation samples obtained in each experimental example were evaluated for various properties (characteristics, surface texture) using the methods described below (sample evaluation). The results are shown in Table 1.

[0100] [Evaluation of Liquid Agents] (3-1) Coatability The coatability of the liquid agents was evaluated by observing coating unevenness after spray coating. An air sprayer was prepared by attaching an air brush (Spraywork HG Single Air Brush: Tamiya Co., Ltd.) to an air can (Spraywork Air Can 420D: Tamiya Co., Ltd.), and each liquid agent was poured into it. Then, the liquid was sprayed toward the outer surface of the object to be coated from a distance of 10 cm from the tip of the air brush for 10 seconds, and the formed solid particle laminate was visually evaluated for coating unevenness. The evaluation criteria are as follows:

[0101] ◯: No uneven coating (uneven thickness) was observed △: Uneven coating was observed in some areas ×: Uneven coating was observed over a large area

[0102] [Sample Evaluation] (3-2) Properties - Glossiness - The glossiness of the coating film surface formed on each evaluation sample with respect to measurement light at an incident angle of 85° (85° specular glossiness) was measured at nine points using a gloss meter (VG 7000: Nippon Denshoku Industries Co., Ltd.) according to a method in accordance with JIS Z8741, and the average value was taken as the glossiness. The evaluation criteria are as follows:

[0103] (85° specular gloss) ◎: Less than 3.5% (very good) ◯: 3.5% or more and less than 4% (good) ×: 4% or more (poor)

[0104] -Reflectance- The reflectance of the coating surface formed on each evaluation sample to light with a wavelength of 905 nm was measured at nine points at 1 nm intervals using a spectrophotometer (CM-5: Konica Minolta) according to a method in accordance with JIS Z8722, and the average value of the measurement results was taken as the reflectance. The evaluation criteria are as follows:

[0105] ◎: Reflectance is 3% or less (very good low reflectance) ◯: Reflectance is more than 3% but not more than 6% (good low reflectance) ×: Reflectance is more than 6% (insufficient low reflectance)

[0106] - Light-blocking property - The light-blocking property of the coating film formed on each evaluation sample was evaluated by calculating the optical density of the coating film. The optical density of the coating film formed on each evaluation sample was calculated using an optical densitometer (X-rite 361T (orthofilter): Nippon Lithopan Kizai Co., Ltd.) by irradiating the coating film side of the sample with a perpendicular transmitted light beam and expressing the ratio to the value in a state without the coating film in log (logarithm). An optical density of 6.0 or higher is the upper detection limit for measurement. The evaluation criteria are as follows:

[0107] ◎: Optical density is 1.8 or more (very good light-blocking property) ◯: Optical density is 1.5 or more and less than 1.8 (good light-blocking property) ×: Optical density is less than 1.5 (insufficient light-blocking property)

[0108] Adhesion: The adhesion of the coating film formed on each evaluation sample to the surface of the substrate was evaluated by making grid-shaped cuts in the coating film with a commercially available cutter knife, sticking cellophane tape (Cellotape, Nichiban Co., Ltd.) to the cuts and then peeling it off, and visually inspecting the remaining state of the coating film. The evaluation criteria are as follows:

[0109] ◎: 100% of the coating film remains (extremely high adhesion) ◯: 75% or more but less than 100% of the coating film remains (high adhesion) ×: Less than 75% of the coating film remains (insufficient adhesion)

[0110] - Overall Evaluation - The glossiness, reflectance, light-blocking property, and adhesion were evaluated overall according to the following criteria.

[0111] ◎: All of the evaluations of glossiness, reflectance, light-blocking property, and adhesion were ◎. ◯: At least one of the evaluations of glossiness, reflectance, light-blocking property, and adhesion was ◯, and none of them was ×. ×: At least one of the evaluations of glossiness, reflectance, light-blocking property, and adhesion was ×.

[0112] (3-3) Surface Properties—Rz Value, Rsm Value, Rsk Value, Rku Value, Ra Value— The properties (Rz value, Rsm value, Rsk value, Rku value, Ra value) of the coating surface formed on each evaluation sample were measured using a surface roughness measuring instrument (SURFCOM 480B: Tokyo Seimitsu Co., Ltd.) according to a method in accordance with JIS B0601:2001. The evaluation criteria are as follows:

[0113] (Rz) ◎: Rz is 10 μm or more (very good) ○: Rz is 7 μm or more and less than 10 μm (good) ×: Rz is less than 7 μm (poor)

[0114] (Rsm) ◎: Rsm is 120 μm or more (very good) ○: Rsm is 80 μm or more and less than 120 μm (good) ×: Rsm is less than 80 μm (poor)

[0115] (Rsk) ◎: Rsk is 0.2 or less (very good) ○: Rsk is more than 0.2 and 0.3 or less (good) ×: Rsk is more than 0.3 (poor)

[0116] (Rku) ⊚: Rku is 3.3 or more (very good) ◯: Rku is 3 or more and less than 3.3 (good) ×: Rku is less than 3 (poor)

[0117] (Ra) ◎: Ra is 1.5 μm or more (very good) ○: Ra is 0.5 μm or more and less than 1.5 μm (good) ×: Ra is less than 0.5 μm (poor)

[0118]

[0119] 4. Discussion As shown in Table 1, when one or more of (B1) and (B2) were not included as (B) in the film-forming solution (Experimental Examples 6, 7, 9, 11, and 12), one or more of the film properties, gloss, reflectance, light-blocking ability, and adhesion, could not be satisfied. On the other hand, even when both (B1) and (B2) were included as (B) in the solution (Experimental Examples 1 to 5, 8, and 10), when the mass ratio of (B2) to (B1):1 was 3.58 or more (Experimental Example 5), the film property of adhesion could not be satisfied. Furthermore, when it was 1.62 or less (Experimental Example 1), the film property of gloss could not be satisfied. Even when both (B1) and (B2) were included and the mass ratio range of (B2) to (B1):1 was appropriate (more than 1.62 and less than 3.58) (Experimental Examples 2 to 4, 13 to 17), when the (B) content (total amount) relative to 100% by mass of the total solids content was less than 20% by mass (Experimental Example 13) or more than 60% by mass (Experimental Example 17), one or more of the film properties, gloss, reflectance, light-blocking ability, and adhesion, could not be satisfied. In contrast, when the mass ratio range of (B2) to (B1):1 was more than 1.62 and less than 3.58 and the total content of (B) relative to 100% by mass of the total solids content of the composition was 20% by mass or more and 60% by mass or less (Experimental Examples 2 to 4, 8, 10, 14 to 16), the coatability of the liquid, as well as the film properties and film condition, could all be satisfied.

[0120] DESCRIPTION OF SYMBOLS 1... Distance measuring device 2... Exterior member 5... Storage chamber 6... Lamp unit 7... LiDAR sensor unit 71... Light emitting element 73... Light receiving element 75... Housing 3... Light-transmitting cover 9, 9a, 9b... Anti-reflection film 8... Processor (control unit) 200... Object (measurement target) 201... Smartphone (an example of an electronic device) 202... Distance measuring module (distance measuring device 1) 203... Imaging device 204... Display 205... Speaker 206... Microphone 207... Communication module 208... Sensor unit 209... Touch panel 210... Control unit (processor 8) 221... Application processing unit 222... Operation system processing unit 211... Bus

Claims

1. A distance measuring device having a light-emitting element that emits detection light for measuring the distance to an object, a light-receiving element that outputs a light-receiving signal according to the amount of incident light, and a light-transmitting cover that covers the light-emitting element and the light-receiving element, wherein the light-transmitting cover has an anti-reflection film on at least one of its main surfaces, and the anti-reflection film is a film having a thickness of 2 μm to 40 μm that is formed by spray coating from a liquid composition, and the liquid composition contains at least (A), (B), and (C), and (B) is contained in an amount of 20% by mass to 60% by mass based on a total amount of 100% by mass of the total solid content of the composition, and (B) contains 90% by mass or more of (B1) and (B2), and the mass ratio of (B2) to (B1):1 is 1.8 to 3.

3. (A) Resin component (B) Bump-forming particles (B1) Particle diameter (d 1 (B2) Inorganic small particles having a particle diameter (d 2 (C) Dilution solvent 2. A distance measuring device as described in claim 1, wherein (B2) includes silica.

3. The distance measuring device according to claim 2, wherein the silica includes a composite silica that has been blackened with a colorant.

4. A distance measuring device according to any one of claims 1 to 3, wherein (B1) contains carbon black.

5. A distance measuring device described in any one of claims 1 to 4, wherein the outermost surface on which the film is formed has a glossiness for incident light at an incidence angle of 85° of less than 4%, a reflectance for light with a wavelength of 905 nm of 6% or less, and an optical density of 1.5 or more.

6. A distance measuring device as described in claim 5, wherein the outermost surface on which the film is formed has a maximum height Rz of 7 μm or more, an average length Rsm of a contour curve element of 80 μm or more, a skewness Rsk of the contour curve of 0.3 or less, and a kurtosis Rku of the contour curve of 3 or more, as measured in JIS B0601:2001.

7. A distance measuring device according to any one of claims 1 to 6, wherein the light emitting element and the light receiving element are part of at least one selected from the group consisting of a LiDAR sensor unit, a ToF camera unit, and a millimeter wave radar unit.

8. An electronic device equipped with a distance measuring device according to any one of claims 1 to 7.

9. A moving object equipped with a distance measuring device according to any one of claims 1 to 7.

10. An anti-reflection film formed at least on a light-transmitting cover of a distance measuring device having a light-emitting element that emits detection light for measuring the distance to an object, and a light-receiving element that outputs a light-receiving signal according to the amount of incident light, the anti-reflection film being composed of a film having a thickness of 2 μm to 40 μm formed by spray coating from a liquid composition, the liquid composition containing at least (A), (B), and (C), (B) being contained in an amount of 20% by mass to 60% by mass based on 100% by mass of the total solid content of the composition, (B) containing 90% by mass or more of (B1) and (B2), and the mass ratio of (B2) to (B1):1 is 1.8 to 3.

3. (A) Resin component (B) Bump-forming particles (B1) Particle diameter (d 1 (B2) Inorganic small particles having a particle diameter (d 2 (C) Dilution solvent

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