Distance measuring device

Abstract

Provided is a distance measuring device (1) capable of achieving high measurement accuracy. The distance measuring device (1) has a LiDAR sensor unit (7) in a storage chamber (5) divided inside an exterior member (2). The LiDAR sensor unit (7) comprises: a light emitting element (71) that emits detection light (L1) for measuring the distance to an object; a light receiving element (73) that outputs a light receiving signal (S1) corresponding to the amount of incident light; and a light-transmitting cover (3) that covers the light emitting element (71) and the light receiving element (73). An anti-reflection film (9a, 9b) is provided on the main surface side of at least one side of the light-transmitting cover (3). The anti-reflection film (9a, 9b) is composed of a film having a thickness of not less than 2 μm and not more than 40 μm formed by spraying, and the film is formed by a liquid composition of a specific composition.

Description

Technical Field

[0001] The present invention relates to a distance measuring device which can be mounted on electronic equipment and a mobile body. Background Art

[0002] As an example of a distance sensor mounted on a vehicle, which is one of the mobile bodies, a LiDAR (Light Detection and Ranging, Laser Imaging Detection and Ranging) sensor unit is known (Patent Document 1). The LiDAR sensor unit detects the distance to an object that generates reflected light based on the flight time of light from emitting detection light to receiving reflected light, so-called ToF (Time of Flight).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2018-49014 Summary of the invention

[0006] Problem that the invention aims to solve

[0007] However, in the conventional LiDAR sensor unit, when the detection light emitted from the light-emitting element passes through the light-transmitting cover, the inner and outer surfaces of the light-transmitting cover may generate reflected light toward the inside (inside the unit). When the reflected light is incident on the light-receiving element and a light-receiving signal based on the reflected light is output from the light-receiving element, it is recognized that there is an object on the inner or outer surface of the light-transmitting cover, resulting in a decrease in the accuracy of the distance measurement to the actual object.

[0008] Secondly, when the reflected light from the object passes through the light-transmitting cover, the inner and outer surfaces of the light-transmitting cover may generate reflected light to the outside (outside the unit). The generation of this reflected light reduces the amount of reflected light incident on the light-receiving element, and in this case, the accuracy of measuring the distance to the object may also be reduced, as described above.

[0009] The present invention has been made in view of the above-mentioned reasons. An object of the present invention is to provide a distance measuring device capable of achieving high measurement accuracy.

[0010] Solutions to the problem

[0011] After in-depth research, the inventors have discovered that the measurement accuracy can be effectively improved by making the light-transmitting cover covering the light-emitting element and the light-receiving element of the distance measuring device meet the following conditions.

[0012] A liquid composition of a specific composition is used, which contains unevenness-forming particles at a specified ratio. The unevenness-forming particles contain inorganic particles having a specified particle size range at a specified mass ratio range.

[0013] Using the liquid composition of the specific composition, an antireflection film having a predetermined thickness is formed on at least one main surface by spray coating.

[0014] The present inventors have completed the invention described below based on the above new findings and have solved the above-mentioned problems.

[0015] In the following, (A) a resin component, (B) concavo-convex forming particles, (B1) small inorganic particles having a particle size (d1) of 0.05 μm to 0.4 μm, (B2) large inorganic particles having a particle size (d2) of 2 μm to 6 μm, and (C) a diluting solvent.

[0016] According to the present invention, a distance measuring device can be provided, which has:

[0017] a light emitting element that emits detection light for measuring a distance to an object;

[0018] a light receiving element that outputs a light receiving signal corresponding to the amount of incident light; and

[0019] A light-transmitting cover covers the light-emitting element and the light-receiving element, wherein:

[0020] The light-transmitting cover has an anti-reflection film on at least one main surface side.

[0021] The antireflection film is composed of a film having a thickness of 2 μm or more and 40 μm or less formed by spray coating, and the film is formed from a liquid composition.

[0022] The liquid composition comprises at least (A), (B) and (C),

[0023] The composition contains 20% by mass or more and 60% by mass or less of (B) in 100% by mass of the total solid content of the composition,

[0024] (B) contains 90 mass % or more of (B1) and (B2), and the mass ratio of (B2) to (B1):1 is 1.8 to 3.3.

[0025] The light emitting element and the light receiving element as constituent members of the distance measuring device may be a 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.

[0026] According to the present invention, there are provided an electronic device and a mobile object including the above-mentioned distance measuring device.

[0027] Examples of electronic devices include smartphones, tablet terminals, mobile phones, personal computers, game consoles, television receivers, wearable terminals, digital still cameras, digital video cameras, etc. Examples of mobile objects include vehicles (automobiles, electric vehicles, hybrid electric vehicles, motorcycles, bicycles, personal transportation vehicles, etc.), aircraft (including drones), ships, robots, etc.

[0028] According to the present invention, an antireflection film can be provided.

[0029] The device is formed at least on a light-transmitting cover of a distance measuring device having a light-transmitting cover, the light-transmitting cover covering 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 corresponding to the amount of incident light.

[0030] It is composed of a film having a thickness of 2 μm or more and 40 μm or less formed by spraying, and the film is formed of a liquid composition.

[0031] The liquid composition comprises at least (A), (B) and (C),

[0032] The composition contains 20% by mass or more and 60% by mass or less of (B) in 100% by mass of the total solid content of the composition,

[0033] (B) contains 90 mass % or more of (B1) and (B2), and the mass ratio of (B2) to (B1):1 is 1.8 to 3.3.

[0034] The anti-reflection film provided by the present invention can be formed on the light-transmitting cover of the distance measuring device, or can be formed on other components. An example of other components will be described later.

[0035] The above liquid composition comprises the following aspects:

[0036] (B2) preferably contains silicon dioxide.

[0037] The silica is preferably a composite silica containing a blackened silica by a colorant.

[0038] (B1) preferably contains carbon black.

[0039] The viscosity at 25°C is preferably 1 mPa·s to 30 mPa·s.

[0040] The anti-reflection film may include the following aspects:

[0041] Preferably, the outermost surface on which the film is formed has a glossiness of less than 4% for incident light at an incident angle of 85° (hereinafter also referred to as “85° glossiness”), a reflectivity of less than 6% for light in the near-infrared region (wavelength 905 nm) (hereinafter also referred to as “reflectivity”), and an optical density of 1.5 or more.

[0042] ·Preferably, the outermost surface of the surface on which the film is formed has a maximum height Rz (hereinafter also referred to as “Rz”) of 7 μm or more in accordance with JIS B 0601:2001, a length average Rsm (hereinafter also referred to as “Rsm”) of the profile curve elements of 80 μm or more, a skewness Rsk (hereinafter also referred to as “Rsk”) of the profile curve of 0.3 or less, and a kurtosis Rku (hereinafter also referred to as “Rku”) of the profile curve of 3 or more.

[0043] Effects of the Invention

[0044] According to the present invention, it is possible to provide a distance measuring device (a LiDAR sensor unit, a ToF camera unit, a millimeter wave radar unit, etc.) capable of achieving high measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a cross-sectional view showing an application example of the distance measuring device according to one embodiment of the present invention.

[0046] Figure 2 It is shown in Figure 1 A diagram showing a structural example of a LiDAR sensor unit used in a ranging device.

[0047] Figure 3 It is shown Figure 2 Diagram of the structure and function of the LiDAR sensor unit.

[0048] Figure 4 This is a block diagram showing a configuration example of an electronic device according to one embodiment of the present invention. DETAILED DESCRIPTION

[0049] The best mode for carrying out the present invention is described below. However, the present invention is not limited to the following mode. A person skilled in the art having general knowledge may make appropriate changes and improvements to the following mode according to his general knowledge without departing from the gist of the present invention. Of course, these also fall within the scope of the present invention.

[0050] In the numerical range described in the present specification, the upper limit or lower limit described in some numerical ranges may be replaced with the numerical values ​​shown in the Examples.

[0051] In this specification, when there are multiple substances corresponding to each component in the composition, the content rate or content of each component in the composition refers to the total content rate or content of the multiple substances present in the composition unless otherwise specified.

[0052] Figure 1 The present invention is an example of a distance measuring device 1 disposed at the left front of a vehicle (leftward of the center in the left-right direction of the vehicle and forward of the center in the front-rear direction). The distance measuring device 1 has an exterior member 2, and a storage chamber 5 is defined inside the exterior member 2.

[0053] The LiDAR sensor unit 7 is disposed in the storage room 5. LiDAR is a sensor that measures the distance to a distant object by measuring diffuse light in response to pulsed laser light.

[0054] like Figure 2 and Figure 3 As shown, the LiDAR sensor unit 7 includes a light emitting element 71 and a light receiving element 73 housed in a housing 75, and a light transmissive cover 3 as a window portion closing an opening 75a of the housing 75. Although the light transmissive cover 3 in this example does not constitute a part of the vehicle exterior surface, it is not limited thereto.

[0055] As an example, the light-transmitting cover 3 is a plate-shaped member made of glass or resin, which is mounted on the end surface 75b of the opening of the housing 75 by, for example, an adhesive, and closes the opening 75a of the housing 75, thereby covering the light-emitting element 71 and the light-receiving element 73. The light-transmitting cover 3 has an optical characteristic of transmitting at least most (for example, more than 99%) of the light in the wavelength band (for example, near-infrared region) of the detection light L1 emitted by the light-emitting element 71.

[0056] Examples of the resin forming the base material of the light-transmitting cover 3 include heat-resistant resins such as polycarbonate (PC)-based resins, polyamide (PA)-based resins, liquid crystal polymers (LCP), and polyacetal (POM)-based resins.

[0057] The substrate of the light-transmitting cover 3 may contain a pigment. The pigment that may be contained is not particularly limited, and any one of resin particles and inorganic particles may be used as (B1) and (B2) described later. As resin particles, for example, melamine resin, benzoguanamine resin, benzoguanamine / melamine / formalin condensate, acrylic resin, ethyl formate resin, styrene resin, fluororesin, silicone resin, etc. may be mentioned. On the other hand, as inorganic particles, for example, silicon dioxide, aluminum oxide, calcium carbonate, barium sulfate, titanium oxide, magnetite black, copper / iron / manganese black, titanium black, carbon black, and aniline black may be mentioned. These pigments may be used alone or in combination of two or more.

[0058] When the pigment is included in the base material of the light-transmitting cover 3, the content ratio of the pigment can be appropriately set according to the required performance, etc., and is not particularly limited. For example, it is 0.3 mass % or more, preferably 0.4 mass % or more, for example, 15 mass % or less, preferably 12 mass % or less, relative to the base material.

[0059] The light emitting element 71 is configured to emit the detection light L1 to the outside of the vehicle. As the detection light L1, for example, near infrared light with a wavelength of 905 nm can be used, and as the light emitting element 71, a semiconductor light emitting element such as a laser diode or a light emitting diode can be used.

[0060] The LiDAR sensor unit 7 may include 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 and scanning a detection area.

[0061] 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, etc. 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.

[0062] The processor (control unit) 8 is arranged in the storage room 5 ( Figure 1 The processor 8 may be built in the housing 75 of the LiDAR sensor unit 7. The processor 8 outputs a control signal S0 for causing the light emitting element 71 to emit the detection light L1 at a desired timing. The processor 8 receives a light receiving signal S1 output by the light receiving element 73.

[0063] The processor 8 calculates the distance to the object 200 that generates the reflected light L2 based on the time from when the light emitting element 71 emits the detection light L1 to when the reflected light L2 enters the light receiving element 73 .

[0064] The light unit 6 is also disposed in the storage room 5 together with the LiDAR sensor unit 7. The light unit 6 is a device that radiates visible light to the outside of the vehicle. Examples of the light unit 6 include a headlight unit, a side light unit, a turn signal unit, and a fog light unit.

[0065] The lamp unit 6 is usually arranged at the four corners of the vehicle. The four corners are also positions where there are few obstacles when detecting the external information of the vehicle. By arranging the LiDAR sensor unit 7 to share the storage chamber 5 with the lamp unit 6, the information outside the vehicle can be detected efficiently.

[0066] In addition, the LiDAR sensor unit 7 can be replaced with an appropriate sensor unit that can be used to measure the distance to the object 200 located outside the vehicle. As such a sensor unit, a ToF camera unit and a millimeter wave radar unit can be listed. A structure using multiple types of measurement methods can be set in a single sensor unit. The wavelength of the detection light L1 emitted by the light emitting element 71 and the light-sensitive wavelength of the light receiving element 73 can be appropriately determined according to the measurement method used.

[0067] (Anti-reflective film)

[0068] An anti-reflection film 9 is provided on a part or all of at least one main surface side of the light-transmitting cover 3. The "main surface" includes the outer surface (hereinafter referred to as the "surface") and the inner surface (hereinafter referred to as the "inside") of the light-transmitting cover 3. Since it is the "main surface side", the anti-reflection film 9 includes not only a method of directly forming on at least one main surface (surface, inside, or both) of the light-transmitting cover 3, but also a method of forming after interposing any layer (such as a primer layer, etc.) between the light-transmitting cover 3 and the anti-reflection film 9. Since it is "part or all", the anti-reflection film 9 includes the case where it is formed on a part of at least one main surface side of the light-transmitting cover 3. At this time, the mirror-like plate-like substrate surface is exposed on at least one main surface side of the light-transmitting cover 3.

[0069] The anti-reflection film 9 may be provided on the end surface (inner end surface, outer end surface, or both inner and outer end surfaces) side together with at least one main surface side of the light-transmitting cover 3. Figure 3 In the example, the case where the antireflection films 9a and 9b are directly formed on the entire surfaces of the two main surfaces (the front surface and the back surface) of the light-transmitting cover 3 is illustrated. The antireflection film 9a is formed on the entire surface of the back surface (inner surface) 3a of the light-transmitting cover 3, and the antireflection film 9b is formed on the entire surface of the front surface (outer surface) 3b of the light-transmitting cover 3.

[0070] The functions of the antireflection film 9 (9a, 9b) are as follows.

[0071] When the detection light L1 emitted by the light emitting element 71 passes through the light-transmitting cover 3, the reflected light L3 toward the inner side is generated due to the back surface 3a of the light-transmitting cover 3. If the reflected light L3 is incident on the light-receiving element 73, and the light-receiving element 73 outputs a light-receiving signal S1 based on the reflected light L3, the processor 8 may recognize that an object exists at the position of the back surface 3a of the light-transmitting cover 3. In addition, when the reflected light L2 from the object 200 passes through the light-transmitting cover 3, the reflected light L4 toward the outer side is generated due to the back surface 3a of the light-transmitting cover 3. The generation of the reflected light L4 results in a reduction in the light amount of the reflected light L2 incident on the light-receiving element 73.

[0072] First, the anti-reflection film 9a suppresses the generation of the reflected light L3. Therefore, the possibility of the reflected light L3 entering the light receiving element 73 can be reduced. Alternatively, the amount of the reflected light L3 entering the light receiving element 73 can be reduced. Thus, the influence of the reflected light L3 on the distance measurement of the LiDAR sensor unit 7 to the object 200 can be suppressed.

[0073] Second, the antireflection film 9a suppresses the generation of the reflected light L4, thereby suppressing a decrease in the amount of the reflected light L2 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.

[0074] When the detection light L1 emitted by the light emitting element 71 passes through the light-transmitting cover 3, the reflected light L5 to the inside is generated due to the surface 3b of the light-transmitting cover 3. If the reflected light L5 enters the light-receiving element 73, and the light-receiving element 73 outputs a light-receiving signal S1 based on the reflected light L5, the processor 8 may recognize that an object exists at the position of the surface 3b of the light-transmitting cover 3. In addition, when the reflected light L2 from the object 200 passes through the light-transmitting cover 3, the reflected light L6 to the outside is generated due to the surface 3b of the light-transmitting cover 3. The generation of the reflected light L6 leads to a reduction in the light amount of the reflected light L2 entering the light-receiving element 73.

[0075] First, the anti-reflection film 9b suppresses the generation of the reflected light L5. Therefore, the possibility of the reflected light L5 entering the light receiving element 73 can be reduced. Alternatively, the amount of the reflected light L5 entering the light receiving element 73 can be reduced. Thus, the influence of the reflected light L5 on the distance measurement of the LiDAR sensor unit 7 to the object 200 can be suppressed.

[0076] Second, the anti-reflection film 9b suppresses the generation of the reflected light L6. Therefore, it is possible to suppress a decrease in the amount of the reflected light L2 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.

[0077] According to the distance measuring device 1 of one embodiment of the present invention, the influence on distance measurement caused by the reflection to the inside by the back surface 3a and the surface 3b of the light-transmitting cover 3 can be suppressed, and the amount of light incident on the light-receiving element 73 caused by the reflection to the outside by the back surface 3a and the surface 3b of the light-transmitting cover 3 can be suppressed, thereby improving the detection accuracy of the distance measuring device 1. That is, higher measurement accuracy is achieved.

[0078] The antireflection film 9 ( 9 a , 9 b ) of this example is constituted by a film formed of a liquid composition.

[0079] <Liquid Composition>

[0080] A liquid composition (hereinafter also referred to as "composition") according to one embodiment is used to form a film on at least one main surface side and the end surface side of a light-transmitting cover 3 (hereinafter also referred to as "the object to be coated"), and includes (A) a resin component, (B) concave-convex forming particles, and (C) a diluting solvent. (B) used to form the composition includes: (B1) small particles with a particle size (d1) of 0.05 μm to 0.4 μm, and (B2) large particles with a particle size (d2) of 2 μm to 6 μm, and may also include components other than (B1) and (B2). That is, the composition according to one embodiment is composed of (A), (B1), (B2), and (C). When the composition according to one embodiment is applied to the surface of the object to be coated, spraying can be applied.

[0081] -(A)-

[0082] (A) used to form the composition becomes the adhesive of (B). The material of (A) is not particularly limited, and any of thermoplastic resins and thermosetting resins can be used. As thermosetting resins, for example, acrylic resins, ethyl formate resins, phenolic resins, melamine resins, urea resins, diallyl phthalate resins, unsaturated polyester resins, epoxy resins, alkyd resins, etc. can be listed. As thermoplastic resins, for example, polyacrylate resins, polyvinyl chloride resins, butyral resins, styrene-butadiene copolymer resins, etc. can be listed. From the viewpoint of heat resistance, moisture resistance, solvent resistance, and surface hardness of the formed concave-convex film, it is preferred to use a thermosetting resin as (A). As a thermosetting resin, when considering the softness and toughness of the formed film, acrylic resin is particularly preferred. (A) can be used alone or in combination of two or more.

[0083] The content (total amount) of (A) is not particularly limited, but considering the ratio with other ingredients, relative to the total amount of all solid components in the composition (100 mass %), 5 mass % or more is preferred, 15 mass % or more is preferred, 25 mass % or more is more preferred, 50 mass % or less is preferred, 45 mass % or less is preferred, and 40 mass % or less is more preferred.

[0084] -(B)-

[0085] (B) used to form the composition must be composed of a plurality of concave-convex particles of different sizes. As (B), (B1) small particles and (B2) large particles are mainly used in combination. For example, when (B) is constructed using only two types of concave-convex particles of different sizes (i.e., (B1) and (B2)), the particle size (d2) of (B2) is preferably 10 times or more, 15 times or more, 40 times or less, and 35 times or less than the particle size (d1) of (B1). When three or more types of concave-convex particles of different sizes are used as (B), the particle size (d2) of the concave-convex particle representing the maximum particle size is preferably 10 times or more, 15 times or more is preferably 15 times or more, 40 times or less is preferably 40 times or less, and 35 times or less is preferably 35 times or less. max ), and the particle size of the concavoconvex forming particles (d min ), that is, (d max ) compared to (d min ), as long as it can be adjusted to 10 times or more, 15 times or more, 40 times or less, and 35 times or less.

[0086] In one embodiment, (d1) is preferably 0.05 μm or more, more preferably 0.1 μm or more, preferably 0.4 μm or less, and more preferably 0.3 μm or less. (d2) is preferably 2 μm or more, more preferably 3 μm or more, preferably 6 μm or less, more preferably 5 μm or less, and even more preferably 4 μm or less.

[0087] The particle size (d1) of (B1) and the particle size (d2) of (B2) are measured by a laser diffraction / scattering particle size distribution measuring device, and the equal volume basis is the median diameter.

[0088] In one embodiment, the mass ratio of (B2) in (B) relative to (B1):1 is preferably greater than 1.62, more preferably greater than 1.8, more preferably less than 3.58, and more preferably less than 3.3. Within this mass ratio range, by using (B1) and (B2) having the above-mentioned specific particle size range in combination, one (B1) can be easily embedded between two adjacent (B2) in the formed film, and as a result, the inventors of the present case have found that low gloss and low reflectivity of the film surface can be achieved.

[0089] The total content (total amount) of (B1) and (B2) in (B) is preferably 90% by mass or more, and 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) preferably contain 90% by mass or more in 100% by mass of (B).

[0090] The content (total amount) of (B) relative to the total amount of all solid components of the composition (100% by mass) is preferably 20% by mass or more, more preferably 25% by mass or more, more preferably 30% by mass or more, preferably 60% by mass or less, preferably 50% by mass or less, more preferably 45% by mass or less, and particularly preferably 40% by mass or less. When the total amount of (B) is less than 20% by mass, the gloss will increase and the optical density will be insufficient. When it exceeds 60% by mass, the amount of (A) in the formed coating film will be relatively small, and as a result, the coating film will fall off from the coated object.

[0091] As (B2), any of resin particles and inorganic particles can also be used. As resin particles, for example, melamine resin, benzoguanamine resin, benzoguanamine / melamine / formalin condensate, acrylic resin, ethyl formate resin, styrene resin, fluororesin, silicone resin, etc. can be listed. On the other hand, as inorganic particles, for example, silicon dioxide, aluminum oxide, calcium carbonate, barium sulfate, titanium oxide, carbon, etc. can be listed. These can be used alone or in combination of two or more.

[0092] In order to obtain more superior properties, (B2) preferably uses inorganic particles. As (B2), by using inorganic particles, a highly light-shielding film with lower gloss can be easily formed. As the inorganic particles used for (B2), silicon dioxide is preferably used. Although the shape of (B2) is not particularly limited, in order to achieve further low gloss, low reflection, and low L value on the surface of the formed film, it is preferred to use particles (sharp-edge products) with a narrower particle size distribution (CV (Coefficient of Variation) value is, for example, less than 15). The CV value is a numerical expression of the degree of diffusion (unevenness of particle size) of the particle size distribution relative to the average particle size (arithmetic mean particle size). By using such particles, the contact opportunity between (B2) and (B1) in the formed film will be increased, thereby easily achieving further low gloss, low reflection, and low L value on the surface of the film.

[0093] In order to further reduce the glossiness of the film-forming surface, it is preferred to use amorphous particles as (B2). Among them, it is particularly preferred to use porous amorphous silica particles as (B2). By using such particles as (B2), the glossiness of the film surface can be further reduced due to repeated refraction of light on the surface and inside of (B2) during film formation.

[0094] In one embodiment, in order to suppress light reflection on the film-forming surface, (B2) may be colored black using an organic or inorganic colorant. Examples of such a material include composite silica, conductive silica, and black silica.

[0095] Examples of composite silica include carbon black (hereinafter also referred to as "CB") and silica synthesized and composited at the nanometer level. Examples of conductive silica include conductive particles such as CB coated on silica particles. Examples of black silica include natural ore containing stone mill in silica.

[0096] On the other hand, as with (B2), the material of (B1) is not particularly limited, and any of resin particles and inorganic particles can be used. Examples of resin particles include melamine resin, benzoguanamine resin, benzoguanamine / melamine / formalin condensate, acrylic resin, ethyl formate resin, styrene resin, fluororesin, silicone resin, etc. On the other hand, examples of inorganic particles include silicon dioxide, aluminum oxide, calcium carbonate, barium sulfate, titanium oxide, CB, etc. These can be used alone or in combination of two or more.

[0097] As (B1), for example, CB added as a coloring agent or a conductive agent may be used. By using CB as (B1), the formed film is colored, so that the antireflection effect can be enhanced and a good antistatic effect can be obtained.

[0098] -(C)-

[0099] The purpose of mixing (C) used to form the composition is to dissolve (A) and adjust the viscosity of the entire composition. By using (C), it will be easier to mix (A) and even other components added as needed, thereby improving the uniformity of the composition. In addition, since the viscosity of the composition can be appropriately adjusted, when a film is formed on the surface of the coated object, it is possible to improve the operability of the composition and the uniformity of the coating thickness.

[0100] As (C), there is no particular limitation as long as it is a solvent that can dissolve (A), and examples thereof include organic solvents and water. As organic solvents, for example, butanone, toluene, propylene glycol monomethyl ether acetate, ethyl acetate, butyl acetate, methanol, ethanol, isopropanol, butanol, etc. (C) can be used alone or in combination of two or more.

[0101] 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, relative to 100 parts by mass of (A) in order to obtain the above-mentioned effect obtained by mixing (C).

[0102] -(D) Optional ingredients-

[0103] In addition to the above-mentioned components ((A), (B), (C)), the composition may also 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, defoamers, hardeners, reaction catalysts, and the like.

[0104] In particular, when a thermosetting resin is used as (A), crosslinking of (A) can be promoted by mixing a curing agent. Examples of the curing agent include urea compounds, melamine compounds, isocyanate compounds, epoxy compounds, aziridine compounds, Azoline compounds, etc. Among them, isocyanate compounds are preferred as hardeners. The hardeners may be used alone or in combination of two or more.

[0105] The ratio of the curing agent when mixed in the composition is preferably 10 parts by mass or more and 80 parts by mass or less relative to 100 parts by mass of (A). By adding the curing agent within this range, the hardness of the formed film can be increased, and as a result, even if the film is placed in an environment where it slides with other members, the properties of the film surface can be maintained for a long time, and low gloss, high light shielding, low reflection and high blackness can be easily maintained.

[0106] When a hardener is mixed in the composition, a reaction catalyst may be used in combination to promote the reaction between (A) and the hardener. Examples of the reaction catalyst include ammonia and ammonium chloride. The proportion of the reaction catalyst in the composition is preferably 0.1 to 10 parts by mass relative to 100 parts by mass of the hardener.

[0107] The composition involved in one embodiment has a viscosity of 1 mPa·s or more, preferably 30 mPa·s or less, and preferably 20 mPa·s or less at 25°C, based on the reason of maintaining the smoothness of the composition on the surface of the coated object and applying (spraying) by spraying. When the viscosity of the composition is too low, it is likely that a film with a thickness sufficient to fully suppress the generation of reflected light L3, L4, L5, and L6 cannot be formed. When the viscosity of the composition is too high, it is likely that the composition cannot be sprayed uniformly on the surface of the coated object, and as a result, a film with a certain thickness and uniform performance cannot be formed.

[0108] The above viscosity varies depending on the components contained in the composition, that is, it varies depending on the type or molecular weight of (A) and (B) used. In addition, when (D) is mixed in addition to the above (A) and (B), it also varies depending on the type or molecular weight of (D). However, it can be easily adjusted by adjusting the content of (C) in the composition within the above range.

[0109] The composition according to one embodiment can be prepared (manufactured) by adding (A) and (B) to (C), and optionally adding (D), and mixing and stirring. The order of mixing the components is not particularly limited as long as the components can be uniformly mixed.

[0110] The composition according to one embodiment of the present invention may be a one-component type or a two-component type. When a hardener (D) is mixed in the composition, the composition according to one embodiment may be, for example, a two-component type including a first liquid containing components other than the hardener and a second liquid containing the hardener.

[0111] The film forming method is not particularly limited. The film can be formed on the object to be coated by any method or device such as spraying (e.g., air spray, airless spray, electrostatic spray, etc.), brush coating, curtain flow coating, roller brush coating, rod coating, kiss-roll, metering roller, gravure roller, reverse roller, dip coating, die casting coating, etc.

[0112] In particular, the composition according to one embodiment is preferably formed into a film by spraying, which requires spraying droplets from a relatively small nozzle hole. In other words, the film formed of the liquid composition according to one embodiment is a sprayed film.

[0113] By spraying the composition involved in one embodiment, droplets formed by the composition gradually adhere to the surface of the object to be coated, and at the same time, (C) in the droplets already attached to the object to be coated will also volatilize. As a result, the solid components (particles) from the droplets, which have (C) removed, gradually accumulate on the surface of the object to be coated to form a solid particle layer. According to one embodiment, this solid particle layer constitutes a film.

[0114] When a thermosetting resin is used as (A) and a composition mixed with a curing agent is used as (D), it is preferred that after the solid particle layer is attached to the surface of the object to be coated, the layer is heated to cure. In this case, even if a small amount of (C) remains in the layer before heating, (C) can be almost completely volatilized by such heating.

[0115] The heating conditions can be appropriately adjusted according to the thickness of the laminate before heating, the heat resistance of the coated object, the type of (C) used, etc. As an example of the heating conditions, it is 70°C to 150°C and 1 minute to 10 minutes, preferably 100°C to 130°C and 2 minutes to 5 minutes.

[0116] As long as the bonding strength between the anti-reflection films 9a, 9b and the light-transmitting cover 3 is good and the generation of reflected light on the surface formed with the films can be suppressed, the film thickness is not particularly limited. As an example of a preferred film thickness, 2 μm or more is preferred, 5 μm or more is preferred, 40 μm or less is preferred, and 25 μm or less is more preferred.

[0117] The film thickness of the antireflection films 9a and 9b is the height including the portion protruding due to (B2) and (B1) of the film from the surface of the coated object. The film thickness can be measured according to the method of JIS K7130.

[0118] <Film Characteristics>

[0119] The properties of a film formed from the composition according to one embodiment are as follows.

[0120] (gloss, reflectivity, optical density, L value, adhesion)

[0121] The film formed from the composition according to one embodiment preferably has a glossiness of less than 4% at 85°, a reflectivity of 6% or less, and an optical density of 1.5 or more.

[0122] Here, if the film formed by the composition involved in one embodiment is configured to be exposed to the outermost surface, as described in the text, the 85° glossiness, reflectivity and optical density of the film surface are preferably set within the above ranges. When other films are coated on the film formed by the composition involved in one embodiment, the 85° glossiness, reflectivity and optical density of the surface of the other film (i.e., the outermost surface of the light-transmitting cover 3) are preferably set within the above ranges. Hereinafter, these surfaces are collectively referred to as "film outermost surfaces".

[0123] The film formed by the composition involved in one embodiment preferably has a 85° glossiness of less than 4%, a reflectivity of less than 6%, and an optical density of 1.5 or more on the outermost surface of the film. By setting the 85° glossiness, reflectivity, and optical density of the outermost surface of the film within the above ranges, low glossiness, low reflectivity (excellent anti-reflection properties, the same below) and high light-shielding properties of the outermost surface of the film can be achieved.

[0124] The upper limit of 85° glossiness is preferably less than 3.5%, and more preferably less than 2.5%. By adjusting 85° glossiness within the above range, the advantage of suppressing light reflection can be easily obtained. The lower limit of 85° glossiness is not particularly limited, and the lower the better.

[0125] The upper limit of the reflectivity is preferably below 3%, and more preferably below 2.5%. The lower limit of the reflectivity is not particularly limited, and the lower the better. By adjusting the reflectivity within the above range, the advantage of preventing sensor errors can be obtained.

[0126] The lower limit of the optical density is preferably 1.8 or more, and more preferably 2.0 or more. By adjusting the optical density within the above range, the light shielding property can be further improved. The upper limit of the optical density is not particularly limited, and the higher the better, for example, less than 3.0.

[0127] In addition to the above, the film formed from the composition according to one embodiment may have an L value of 22 or less on the outermost surface of the film. The upper limit of the L value (blackness) is preferably 20 or less, and more preferably 18 or less. The lower limit of the L value is not particularly limited.

[0128] The above L value is the lightness L* value of the outermost surface of the film expressed in the CIE 1976 L*a*b* (CIELAB) color system using the SCE method. The so-called SCE method is a method of removing regular reflected light, which means a method of measuring color by removing regular reflected light. The definition of the SCE method is stipulated in JIS Z 8722 (2009). Since the SCE method removes regular reflected light for measurement, the color is close to the color actually seen by the human eye.

[0129] CIE is the abbreviation of Commission internationale de 1'é clairage, which means International Commission on Illumination. CIELAB display color is an equal color space recommended in 1976 and stipulated in JIS Z 8781 (2013) in order to measure the color difference caused by differences in perception and equipment. The three coordinates of CIELAB represent L* value, a* value, and b* value. L* value represents lightness and is expressed in 0-100. When L* value is 0, it means black, and when L* value is 100, it means diffuse white color. a* value represents the color between red and green. If a* value is negative, it means the color is close to green, and if it is positive, it means the color is close to red. b* value represents the color between yellow and blue. If b* value is negative, it means the color is close to blue, and if it is positive, it means the color is close to yellow.

[0130] The glossiness, reflectance, optical density and L value can be measured by the method described later.

[0131] The film formed by the composition preferably has, in addition to the above-mentioned properties (gloss, reflectivity, optical density, L value), further good adhesion of the film to the surface of the coated object. As shown in the adhesion evaluation disclosed in the examples described below, the adhesion of the film formed by the composition to the surface of the coated object is preferably 75% or more of the coating film residue.

[0132] (Rz, Rsm, Rsk, Rku, Ra)

[0133] The film formed from the composition according to one embodiment preferably has a maximum height Rz of 7 μm or more on the outermost surface of the film, a length average Rsm of the profile curve elements of 80 μm or more, a skewness Rsk of the profile curve of 0.3 or less, and a peak Rku of the profile curve of 3 or more. By setting Rz, Rsm, Rsk, and Rku of the outermost surface of the film to the above ranges, the glossiness, reflectivity, and optical density of the outermost surface of the film can be within the above ranges (85° glossiness less than 4%, reflectivity less than 6%, and optical density greater than 1.5), and as a result, low glossiness, low reflectivity, and high light-shielding properties of the outermost surface of the film can be achieved.

[0134] The lower limit of Rz is preferably 10 μm or more. By setting the lower limit of Rz to the above value, it is easier to adjust low glossiness, low reflectivity, and high light shielding properties.

[0135] 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, further low gloss, low reflectivity, and high light shielding properties of the outermost surface of the film can be easily achieved.

[0136] Rsm is the average length of the contour curve element in the reference length. The lower limit of Rsm is preferably 100 μm or more, and more preferably 120 μm or more. By setting the lower limit of Rsm to the above value, the advantage of low gloss can be obtained more easily. Although the upper limit of Rsm is not particularly limited, it is preferably 160 μm or less. Within the above range, a more superior adhesion can be obtained between the coated object and the film formed thereon.

[0137] Rsk is an index that represents the cube of the height Z(x) in the dimensionless reference length averaged by the cube of the root mean square height (Zq), and represents the deviation of the average line of the concave and convex shape of the outermost surface of the film, that is, an index representing the degree of deformation. If the value of Rsk is positive (Rsk>0), the concave and convex shape is biased toward the concave side, resulting in sharp protrusions. If it is negative (Rsk<0), the concave and convex shape is biased toward the convex side, resulting in a tendency for the protrusions to be blunt. When the protrusions of the contour curve are blunt, the haze will be lower than when they are sharp.

[0138] The upper limit of Rsk is preferably below 0.2. By setting the upper limit of Rsk to the above value, the advantage of low gloss can be obtained more easily. Although the lower limit of Rsk is not particularly limited, it is preferably above 0. By setting the lower limit of Rsk to the above value, the advantage of low gloss can be easily obtained.

[0139] Rku is an index that represents the fourth power average of the height Z(x) in the dimensionless reference length through the fourth power of the root mean square height (Zq), and represents the sharpness of the front end of the concave and convex surface of the film. As Rku increases, the front ends of more concave and convex parts become sharper, so the inclination angle near the front end of the concave and convex part becomes larger, but the inclination angle of other parts becomes smaller, resulting in a tendency to easily weaken the strength of the front end and cause the coating to fall off. In addition, as Rku decreases, the front ends of more concave and convex parts become flat, so the inclination angle of the front end of the concave and convex part becomes smaller, resulting in a tendency to easily cause the disadvantage of an increase in 85° glossiness.

[0140] The lower limit of Rku is preferably 3.3 or more. By setting the lower limit of Rku to the above value, the advantage of low gloss can be more easily 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 can be more easily obtained.

[0141] 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.

[0142] In addition, Rz, Rsm, Rsk, Rku and Ra of the outermost surface of the film as described above can be measured and calculated in accordance with JIS B0601:2001.

[0143] (Other embodiments)

[0144] The anti-reflection film 9 of the above-mentioned method can be formed directly without pre-treatment or formed on at least one main surface side of the light-transmitting cover 3 after pre-treatment, but is not limited to this method. For example, an anti-reflection film sheet on which the anti-reflection film 9 is formed by spraying on an ultra-thin plastic film (PET film, etc.) is prepared, and the sheet is cut to be consistent with the shape of at least one main surface side of the light-transmitting cover 3. After obtaining the sheet, the sheet is attached to at least one main surface side of the light-transmitting cover 3 via an adhesive layer, and finally the anti-reflection film 9 is formed.

[0145] The anti-reflection film 9 of the above embodiment is not limited to being formed on the light-transmitting cover 3, and may be formed on other components of the distance measuring device 1 (e.g., the outer casing 2, the inner wall of the housing 75 of the LiDAR sensor unit 7). The material of the other components that can form the anti-reflection film 9 is not limited to glass or resin, and may be metal, such as SUS or aluminum.

[0146] (Application example)

[0147] The distance measuring device 1 involved in the above-mentioned method can also be implemented as a device mounted on other vehicles (motorcycles, bicycles, personal transportation vehicles, etc.) other than four-wheeled vehicles (automobiles, electric vehicles, hybrid electric vehicles, etc.), aircraft (including drones), ships, robots and other mobile bodies.

[0148] The distance measuring device 1 according to the above embodiment may be mounted on various electronic devices such as smartphones, tablet terminals, mobile phones, personal computers, game consoles, television receivers, wearable terminals, digital still cameras, digital video cameras, etc. The following describes the case where the device is mounted on a smartphone.

[0149] like Figure 4 As shown, the smartphone 201 includes a distance measuring module 202, a camera 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. In the control unit 210, the CPU executes a program to function as an application processing unit 221 and an operating system processing unit 222.

[0150] The ranging module 202 applies Figure 2 and 3 The LiDAR sensor unit 7. For example, the distance measurement module 202 is arranged in front of the smartphone 201, performs distance measurement for the user of the smartphone 201, and can output various information as the distance measurement result. Figure 3 The processor 8 corresponds to Figure 4 The control unit 210 of FIG.

[0151] The camera device 203 is disposed on the front of the smartphone 201, and acquires an image of the user by taking the user of the smartphone 201 as the subject. In addition, the camera device 203 may also be disposed on the back of the smartphone 201, although not shown.

[0152] The display 204 displays an operation screen and images captured by the camera 203 for processing by the application processing unit 221 and the operating system processing unit 222. The speaker 205 and the microphone 206 output the other party's voice and receive the user's voice when making a call via the smartphone 201, for example.

[0153] The communication module 207 performs communication via a communication network. The sensor unit 208 senses speed, acceleration, proximity, and the like, and the touch panel 209 acquires a touch operation of the user on an operation screen displayed on the display 204 .

[0154] The application processing unit 221 performs processing for providing various services by the smartphone 201. For example, the application processing unit 221 can generate a face based on computer graphics that virtually reproduces the user's expression based on the information provided by the ranging module 202, and display it on the display 204. In addition, the application processing unit 221 can perform processing such as generating three-dimensional shape data of an arbitrary three-dimensional object based on the information provided by the ranging module 202.

[0155] The operating system processing unit 222 performs processing for realizing basic functions and operations of the smartphone 201. For example, the operating system processing unit 222 can authenticate the user's face based on the information provided from the ranging module 202, and perform processing for unlocking the smartphone 201. The operating system processing unit 222 can perform processing such as recognizing a user's gesture based on the information provided from the ranging module 202, and performing processing for inputting various operations based on the gesture.

[0156] [Example]

[0157] Hereinafter, the present invention will be specifically described based on experimental examples (including examples and comparative examples), but the present invention is not limited to these experimental examples. In the following description, "part" means "part by mass" and "%" means "% by mass".

[0158] [Composition components]

[0159] As A (resin component), the following items were prepared.

[0160] A1: Thermosetting acrylic resin

[0161] (ACRYDIC A801, manufactured by DIC Corporation, solid content 50%)

[0162] As B1 (small particles) belonging to B (concavity-forming particles), the following were prepared.

[0163] B1a: Carbon black (CB) (particle size 150nm)

[0164] (MHI Black_#273, manufactured by Mikoku Color Co., Ltd., CB content 9.5%)

[0165] B1b: Transparent silica (particle size 58nm)

[0166] (ACEMATT R972, manufactured by EVONIK)

[0167] As B2 (large particles) belonging to B, the following items were prepared.

[0168] B2a: Composite silica (particle size 3 μm)

[0169] (BECSIA ID, manufactured by FUJI SILYSIA Chemical Co., Ltd.)

[0170] B2b: Black acrylic beads (particle size 3μm)

[0171] (RUBCOULEUR 224SMD black, manufactured by Dainichi Seika Industries Co., Ltd.)

[0172] B2c: Transparent silica (particle size 4.1 μm)

[0173] (SYLYSIA 430, manufactured by FUJI SILYSIA CHEMICAL CO., LTD.)

[0174] B2d: Transparent silica (particle size 8 μm)

[0175] (SYLYSIA 450, manufactured by FUJI SILYSIA CHEMICAL CO., LTD.)

[0176] B2e: Transparent acrylic beads (particle size 3μm)

[0177] (Uni powder-NMB-0320C, manufactured by ENEOS)

[0178] In addition, the BECSIAID used in B2a (composite silica) is a composite particle of CB and silica with CB / silica = about 25 / 75 (mass ratio). The MHI Black_#273 used in B1a (CB) is a CB dispersion, of which 9.5% is CB and the remaining 8.5% is other compounds out of the total solid content of 18%. Of the 8.5% other compounds, 3% are copper compounds and 5.5% are acrylic resins.

[0179] As D (optional component), the following items were prepared.

[0180] ·D1: Isocyanate compound

[0181] (TAKENATE D110N, manufactured by Mitsui Chemicals, solid content 75%)

[0182] [Object to be painted]

[0183] As the coating object, a sample substrate for evaluation was prepared. As the sample substrate for evaluation, a black polycarbonate sheet was used, and both sides of the plate surface in the thickness direction (X direction) were matte-finished to form a rectangular polycarbonate flat plate (length 100 mm, width 50 mm, thickness 1.5 mm).

[0184] [Experimental Examples 1 to 17]

[0185] 1. Preparation of the composition

[0186] In order to make the solid content ratio as shown in Table 1, so that the total solid content is about 25% by mass, each component of each experimental example is placed in a required amount of a mixed solvent (methyl ethyl ketone: butyl acetate = 50:50) as (C) a diluent solvent, and stirred and mixed to prepare a liquid composition, which is hereinafter also referred to as a "liquid".

[0187] 2. Preparation of samples for evaluation

[0188] The liquid obtained in each experimental example was sprayed using the coating method described in (3-1) below. After spraying toward one side of the object to be coated (glass flat plate), the sample for evaluation was dried by heating at 120°C for 3 minutes. The sample was a heated coating film having an average film thickness of 20 μm formed on the surface of the object to be coated by a layer of solid particles obtained by spraying, hereinafter referred to as a “coating film”.

[0189] 3. Evaluation

[0190] For the liquid obtained in each experimental example, various characteristics (applicability) were evaluated by the following method (liquid evaluation). In addition, for the coating film formed on the evaluation sample obtained in each experimental example, various characteristics (characteristics, surface properties) were evaluated by the following method (sample evaluation). The results are shown in Table 1.

[0191] [Liquid agent evaluation]

[0192] (3-1) Coating properties

[0193] The coating properties of the liquid agent were evaluated by observing the coating unevenness after spraying.

[0194] Each liquid agent was injected into an air sprayer, i.e., an air brush (SPRAY-WORK HG single air brush, manufactured by TAMIYA) was mounted on an air can (SPRAY-WORK AIR CAN 420D, manufactured by TAMIYA), and sprayed from the tip of the air brush to a distance of 10 cm toward the outer surface of the object to be coated for 10 seconds, and then the formed solid particle layer was visually evaluated for uneven coating. The evaluation criteria were as follows.

[0195] ○: Uneven coating (uneven thickness) not observed

[0196] △: Uneven coating was observed in some areas

[0197] ×: Uneven coating was observed in most areas

[0198] [Sample evaluation]

[0199] (3-2) Characteristics

[0200] -Glossiness-

[0201] The glossiness of the coating film surface formed on each evaluation sample with respect to the measurement light at an incident angle of 85° (85° specular glossiness) was measured at 9 points using a gloss meter (VG 7000, manufactured by Nippon Denshoku Industries) according to the method shown in JIS Z8741, and the average value was taken as the glossiness. The evaluation criteria were as follows.

[0202] (85° mirror gloss)

[0203] ◎: Glossiness less than 3.5% (extremely excellent)

[0204] ○: Glossiness is 3.5% or more and less than 4% (excellent)

[0205] ×: Glossiness is 4% or more (inadequate)

[0206] -Reflectivity-

[0207] The reflectance of the coating surface formed on each evaluation sample with respect to light of a wavelength of 905 nm was measured at 9 points at 1 nm intervals using a spectrophotometer (CM-5, manufactured by Konica Minolta) according to the method shown in JIS Z8722, and the average value of the measurement results was taken as the reflectance. The evaluation criteria were as follows.

[0208] ◎: Reflectivity is 3% or less (extremely good low reflectivity)

[0209] ○: Reflectivity is more than 3% and less than 6% (good low reflectivity)

[0210] ×: Reflectivity exceeds 6% (low reflectivity is insufficient)

[0211] -Light blocking properties-

[0212] The light-shielding property of the coating formed on each evaluation sample is evaluated by calculating the optical density of the coating. The optical density of the coating formed on each evaluation sample is calculated by using an optical densitometer (X-rite 361T (Orthofilter), manufactured by Japan Flatbed Machinery Co., Ltd.) to irradiate the vertically transmitted light beam to the coating side of the sample and express the ratio to the non-coating state in log (logarithm). An optical density of 6.0 or more is the upper limit of the detection value measured. The evaluation criteria are as follows.

[0213] ◎: Optical density is 1.8 or more (extremely good light shielding properties)

[0214] ○: Optical density is 1.5 or more and less than 1.8 (good light shielding property)

[0215] ×: Optical density is less than 1.5 (light shielding property is insufficient)

[0216] - Adhesion -

[0217] The adhesion of the coating formed on each evaluation sample to the surface of the coated object was evaluated by scratching the coating with a commercially available utility knife into a checkerboard pattern, sticking a transparent tape (Cellotape, manufactured by NICHIBAN) on it, and then tearing it off to visually confirm the residual state of the coating. The evaluation criteria are as follows.

[0218] ◎: 100% coating residue (extremely high adhesion)

[0219] ○: The coating film remains 75% or more and less than 100% (high adhesion)

[0220] ×: The coating film remains less than 75% (insufficient adhesion)

[0221] - Comprehensive Assessment -

[0222] The glossiness, reflectivity, light shielding properties, and adhesiveness were comprehensively evaluated. The evaluation criteria are as follows.

[0223] ◎: Glossiness, reflectivity, light shielding and adhesion are all ◎

[0224] ○: At least one of the evaluations of glossiness, reflectivity, light shielding property, and adhesiveness is ○, and none of them is ×

[0225] ×: At least one of the evaluations of glossiness, reflectivity, light shielding property, and adhesion was ×

[0226] (3-3) Surface properties

[0227] -Rz value, Rsm value, Rsk value, Rku value, Ra value-

[0228] 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 machine (SURFCOM 480B, manufactured by Tokyo Seimitsu Co., Ltd.) according to the method described in JIS B0601: 2001. The evaluation criteria are as follows.

[0229] (Rz)

[0230] ◎: Rz is 10 μm or more (extremely good)

[0231] ○: Rz is 7 μm or more and less than 10 μm (good)

[0232] ×: Rz less than 7μm (defective)

[0233] (Rsm)

[0234] ◎: Rsm is 120 μm or more (extremely good)

[0235] ○: Rsm is 80 μm or more and less than 120 μm (good)

[0236] ×: Rsm less than 80μm (defective)

[0237] (Rsk)

[0238] ◎: Rsk is 0.2 or less (extremely good)

[0239] ○: Rsk is more than 0.2 and less than 0.3 (good)

[0240] ×: Rsk is more than 0.3 (defective)

[0241] (Rku)

[0242] ◎: Rku is 3.3 or more (extremely good)

[0243] ○: Rku is 3 or more and less than 3.3 (good)

[0244] ×: Rku is less than 3 (defective)

[0245] (Ra)

[0246] ◎: Ra is 1.5 μm or more (extremely good)

[0247] ○: Ra is 0.5 μm or more and less than 1.5 μm (good)

[0248] ×: Ra less than 0.5 μm (poor)

[0249] [Table 1]

[0250]

[0251] 4. Investigation

[0252] As shown in Table 1, when the liquid does not contain at least one of (B1) and (B2) as (B) (Experimental Examples 6, 7, 9, 11, 12), at least one of the glossiness, reflectivity, light shielding, and adhesion of the film characteristics cannot be satisfied. On the other hand, even if the liquid contains both (B1) and (B2) as (B) (Experimental Examples 1 to 5, 8, 10), if the mass ratio of (B2) to (B1):1 is 3.58 or more (Experimental Example 5), the adhesion of the film characteristics cannot be satisfied. If it is less than 1.62 (Experimental Example 1), the glossiness of the film characteristics cannot be satisfied. Even if both (B1) and (B2) are contained and the mass ratio range of (B2) relative to (B1):1 is an appropriate value (greater than 1.62 and less than 3.58) (Experimental Examples 2 to 4, 13 to 17), when the (B) content (total amount) in 100 mass% of the total solid components is less than 20 mass% (Experimental Example 13) or exceeds 60 mass% (Experimental Example 17), it will not be possible to satisfy one or more of the film properties of gloss, reflectivity, light shielding, and adhesion.

[0253] In contrast, when the mass ratio of (B2) to (B1):1 is greater than 1.62 and less than 3.58, and the total amount of (B) contained in the composition relative to 100% by mass of the total solid content is greater than 20% by mass and less than 60% by mass (Experimental Examples 2 to 4, 8, 10, 14 to 16), all the coating properties, film characteristics and film shapes of the liquid can be met.

[0254] Explanation of symbols

[0255] 1: Distance measuring device

[0256] 2: External components

[0257] 5: Storage Room

[0258] 6: Light unit

[0259] 7: LiDAR sensor unit

[0260] 71: Light-emitting element

[0261] 73: Light receiving element

[0262] 75: Shell

[0263] 3: Transparent cover

[0264] 9, 9a, 9b: Anti-reflective film

[0265] 8: Processor (control unit)

[0266] 200: Object (measurement object)

[0267] 201: Smartphone (an example of an electronic device)

[0268] 202: Distance measurement module (distance measurement device 1)

[0269] 203: Camera device

[0270] 204: Display

[0271] 205: Speaker

[0272] 206: Microphone

[0273] 207: Communication module

[0274] 208: Sensor unit

[0275] 209: Touch panel

[0276] 210: control unit (processor 8)

[0277] 221: Application Processing Unit

[0278] 222: Operation System Processing Department

[0279] 211: Bus

Claims

1. A distance measuring device, comprising: a light emitting element that emits detection light for measuring a distance to an object; A light receiving element that outputs a light receiving signal corresponding to the amount of incident light; a light-transmitting cover covering the light-emitting element and the light-receiving element, in, The light-transmitting cover has an anti-reflection film on at least one main surface side. The antireflection film is composed of a film having a thickness of 2 μm or more and 40 μm or less formed by spray coating, and the film is formed of a liquid composition. The liquid composition comprises at least (A), (B) and (C), The composition contains 20% by mass or more and 60% by mass or less of (B) in 100% by mass of the total solid content of the composition, (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) is a resin component, (B) is a concavoconvex forming particle, (B1) is an inorganic small particle having a particle size (d1) of 0.05 μm or more and 0.4 μm or less, (B2) is an inorganic large particle with a particle size (d2) of 2 μm or more and 6 μm or less, (C) is a diluting solvent.

2. The distance measuring device according to claim 1, wherein: (B2) contains silicon dioxide.

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

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

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

6. The distance measuring device according to claim 5, wherein: The outermost surface of the film-formed surface has a maximum height Rz of 7 μm or more according to JIS B0601:2001, a length average Rsm of profile elements of 80 μm or more, a profile skewness Rsk of 0.3 or less, and a profile kurtosis Rku of 3 or more.

7. The 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 comprising the distance measuring device according to any one of claims 1 to 7.

9. A mobile object comprising the distance measuring device according to any one of claims 1 to 7.

10. An antireflection film formed at least on a light-transmitting cover of a distance measuring device having a light-transmitting cover, the light-transmitting cover covering a light-emitting element and a light-receiving element, the light-emitting element emitting detection light for measuring the distance to an object, the light-receiving element outputting a light-receiving signal corresponding to the amount of incident light, It is composed of a film having a thickness of 2 μm or more and 40 μm or less formed by spraying, and the film is formed of a liquid composition. The liquid composition comprises at least (A), (B) and (C), The composition contains 20% by mass or more and 60% by mass or less of (B) in 100% by mass of the total solid content of the composition, (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) is a resin component, (B) is a concavoconvex forming particle, (B1) is an inorganic small particle having a particle size (d1) of 0.05 μm or more and 0.4 μm or less, (B2) is an inorganic large particle with a particle size (d2) of 2 μm or more and 6 μm or less, (C) is a diluting solvent.

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