On-vehicle lens, lens unit, camera module, and method for manufacturing lens

Abstract

Provided are: an on-vehicle lens having a resin as a main component and a transparent base member, wherein a hard coat layer and an antireflection layer are provided on at least one surface of the base member, the antireflection layer is provided on the side opposite to the base member with respect to the hard coat layer, the region from a lens effective diameter to an edge part in the base member is defined as an effective diameter outer region, and the antireflection layer is covered with a functional film for absorbing ultraviolet rays in the effective diameter outer region; a lens unit having the on-vehicle lens; and a camera module having the lens unit.

Description

In-vehicle lens, lens unit, camera module, and lens manufacturing method

[0001] The present invention relates to an on-vehicle lens having a lens primarily made of resin. More specifically, the present invention relates to an on-vehicle lens having a hard coat layer, an anti-reflection layer, and an ultraviolet absorbing film on the surface of the lens primarily made of resin. The present invention also relates to a lens unit having the on-vehicle lens and a camera module having the lens unit. The present invention also relates to a method for manufacturing the lens.

[0002] In recent years, the applications of in-vehicle cameras mounted on automobiles have expanded to include image recognition cameras for parking support and collision prevention. In particular, with the growing social demand for autonomous driving, the performance requirements for in-vehicle lenses are increasing, and it is expected that demand for image recognition cameras will continue to grow in the future.

[0003] In-vehicle cameras are also used in dashcams, and demand for dashcams is expected to continue to grow in the future, so the demand for in-vehicle lenses used in dashcams is also expected to grow.

[0004] On the other hand, plastic lenses, which are lenses whose main component is resin, are superior in formability, lightweight, and cost-effective compared to conventional lenses whose main component is glass, and therefore, their use in various applications is being considered. In particular, the use of plastic lenses in in-vehicle cameras, for which demand is expected to grow, is an important issue.

[0005] However, compared to lenses primarily made of glass, plastic lenses are prone to scratches due to their insufficient hardness. Therefore, in lens units combining multiple lenses, it has been necessary to improve the surface hardness of the plastic lens used on the subject side. For example, in the case of optical lenses for eyeglasses, a proposal has been made to form a hard coating layer adjacent to a lens substrate made of plastic (see, for example, Patent Document 1).

[0006] Japanese Patent Application Laid-Open No. 2016-173613

[0007] The optical lens described in Patent Document 1 has a hard coat layer on the surface of the lens substrate, which improves the surface hardness of plastic lenses, which have traditionally lacked hardness, and is expected to result in improved durability. That is, the optical lens described in Patent Document 1 could be applied to an in-vehicle lens unit using the optical lens as the outermost lens. However, when an optical lens having a configuration as described in Patent Document 1 is manufactured, in which a hard coat layer is provided on the surface of a lens substrate made from plastic and an anti-reflection layer is further formed on the hard coat layer, the hard coat layer may not be covered by the anti-reflection layer around the edge of the optical lens due to the manufacturing process. If the hard coat layer is made thicker to increase the surface hardness, when the optical lens is exposed to sunlight containing ultraviolet rays for a long period of time, the hard coat layer around the edge of the optical lens that is not covered by the anti-reflection layer may be deteriorated by the ultraviolet rays, and the anti-reflection layer above the deteriorated hard coat layer may also be deteriorated.

[0008] The present inventors have conducted extensive research to develop a plastic lens in which the deterioration of the antireflection function of the antireflection layer is suppressed even with long-term use. That is, an object of the present invention is to provide an in-vehicle lens in which the deterioration of the antireflection function is suppressed even with long-term use.

[0009] The present invention provides an on-vehicle lens having a transparent base member mainly composed of resin, wherein a hard coat layer and an anti-reflection layer are provided on at least one surface of the base member, the anti-reflection layer is provided on the opposite side of the hard coat layer from the base member, an outer effective diameter region extends from the lens effective diameter to the edge of the base member, and the anti-reflection layer is covered in the outer effective diameter region with a functional film that absorbs ultraviolet light.

[0010] According to the present invention, there is provided an in-vehicle lens in which deterioration of the anti-reflection function is suppressed even with long-term use. Furthermore, according to the present invention, there are provided a lens unit including the in-vehicle lens, and a camera module including the lens unit.

[0011] FIG. 1 is a schematic diagram of an on-vehicle lens of the present invention, drawn from above along the optical axis. FIG. 2 is a schematic diagram of the left half of the cross-sectional view of the A-A' cross section passing through the optical axis in FIG. 1. FIG. 3 is a schematic diagram of a first area and a second area in FIG. 2. FIG. 4 is a schematic diagram of an embodiment having a water-repellent layer. FIG. 5 is a schematic diagram of another embodiment having a water-repellent layer. FIG. 6 is a schematic diagram of an embodiment having a protective film. FIG. 7 is a schematic diagram of a lens unit having an on-vehicle lens of the present invention. FIG. 8 is a diagram showing the relationship between the transmittance of a functional film used in the examples and the wavelength of light.

[0012] The vehicle-mounted lens of the present invention (hereinafter also referred to as "the vehicle-mounted lens") is a vehicle-mounted lens having a transparent base member whose main component is resin, wherein a hard coat layer and an anti-reflection layer are provided on at least one surface of the base member, the anti-reflection layer being provided on the opposite side of the base member from the hard coat layer, and an outer-effective-diameter region extending from the lens effective diameter to the edge of the base member is defined as a region outside the effective diameter, and in this outer-effective-diameter region, the anti-reflection layer is covered with a functional film that absorbs ultraviolet light. It has been found that this configuration prevents deterioration of the anti-reflection function of the lens even during long-term use. The reasons for this are thought to be as follows.

[0013] Transparent base materials primarily made of resin have a high expansion coefficient, and when used in an environment with large temperature changes, such as the inside of a car, their volume changes significantly. Therefore, if an anti-reflection layer is formed directly on a lens primarily made of resin, the anti-reflection layer will not be able to keep up with the volume changes of the lens primarily made of resin, which can lead to partial peeling of the anti-reflection layer from the lens primarily made of resin, or the formation of air bubbles between the anti-reflection layer and the lens primarily made of resin. As a result, the anti-reflection function of the anti-reflection layer will deteriorate if the lens is used for a long period of time as an in-vehicle lens.

[0014] On the other hand, by providing a hard coat layer between the resin-based lens and the anti-reflection layer, the hard coat layer also serves as a buffer and is thought to be effective in compensating for the difference in volume expansion between the resin-based lens and the anti-reflection layer, thereby suppressing the deterioration of the anti-reflection function.

[0015] However, the hard coat layer may not be covered by the anti-reflection layer around the edge of the lens. This is because the anti-reflection layer is often formed on the hard coat layer by a dry process such as sputtering, and as described below, the lens is held in a state where the edge of the lens is covered, so the hard coat layer around the edge of the lens may not be covered by the anti-reflection layer. As described below, the anti-reflection layer has the function of reflecting ultraviolet rays. Therefore, if the hard coat layer around the edge of the lens is thickened to achieve a high hardness (e.g., pencil hardness of 5H or more) while ultraviolet rays are not reflected by the anti-reflection layer, the hard coat layer around the edge of the lens may be deteriorated by ultraviolet rays. If the hard coat layer deteriorates, the buffer function described above will be reduced, and there is a risk that the anti-reflection layer will partially peel off from the hard coat layer. In other words, it is believed that the anti-reflection function of vehicle lenses will deteriorate over long-term use. In this vehicle lens, by providing a functional film that absorbs ultraviolet rays around the edge of the lens, the hard coat layer that is not covered by the anti-reflection layer is protected from ultraviolet rays, so the buffering function of the hard coat layer is maintained for an even longer period of time, and as a result, it is thought that the deterioration of the anti-reflection function over long periods of use is further suppressed.

[0016] The transparent base member used in the vehicle-mounted lens, which is primarily composed of a resin, is transparent to visible light and has a high refractive index. The resin used is typically amorphous and preferably has a high glass transition temperature from the viewpoint of hardness. The glass transition temperature of the resin is typically measured in accordance with JIS-K7121, and a resin with a glass transition temperature of 110°C or higher is preferred, with 130°C or higher being more preferred. Furthermore, from the viewpoint of the moldability of the base member, the glass transition temperature of the resin that is the primary component of the base member is preferably 200°C or lower. From the viewpoint of the balance between hardness and moldability, the glass transition temperature of the resin that is the primary component of the base member is preferably 110°C or higher and 200°C or lower, and from the viewpoint of thermal stability, it is more preferred to have a glass transition temperature of 130°C or higher and 200°C or lower.

[0017] Examples of the resin include acrylic resin, polycarbonate, polystyrene, polyvinyl chloride, urethane resin, thiourethane resin, episulfide-based resin, diallyl phthalate-based resin, etc. Examples of the acrylic resin include polymethyl methacrylate, polymethacrylate, polybutyl methacrylate, epoxy methacrylate, urethane methacrylate, etc. Examples of the polycarbonate include polydiethylene glycol bisallyl carbonate, allyl diglycol carbonate, etc.

[0018] Furthermore, a resin having a cyclic imide structure as a ring structure is also preferred as the resin that is the main component of the base member. More specifically, a methacrylic resin having a structural unit with a ring structure in its main chain, and containing at least one structural unit selected from structural units derived from N-substituted maleimide monomers and glutarimide structural units, is preferred from the viewpoints of both heat resistance and optical properties. For example, the resin that is the main component of the base member is preferably a resin that contains a structural unit (X) having the above-mentioned ring structure in its main chain and a structural unit (Y) derived from a methacrylic acid ester monomer. It is more preferred that the resin that is the main component of the base member is a resin consisting only of the structural unit (X) and the structural unit (Y).

[0019] Lens members primarily composed of resins having a cyclic imide structure are transparent and have a glass transition temperature Tg that is 30°C to 40°C higher than that of ordinary methacrylic resins. Therefore, when a lens member primarily composed of a resin having a cyclic imide structure is used, it will not deform even when exposed to a temperature of, for example, 110°C, and its light transmittance exceeds 90%. Examples of such resins are described in, for example, JP 2018-53044 A and JP 2020-63436 A.

[0020] The structural unit (Y) derived from a methacrylic acid ester monomer is derived from, for example, one or more monomers selected from the following methacrylic acid esters: Examples of methacrylic acid esters include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, cyclopentyl methacrylate, cyclohexyl methacrylate, cyclooctyl methacrylate, tricyclodecyl methacrylate, dicyclooctyl methacrylate, and tricyclododecyl methacrylate.

[0021] The structural unit (X) derived from the N-substituted maleimide monomer is formed from one or more structural units selected from the group consisting of structural units represented by the following formula (1) and structural units represented by the following formula (2):

[0022] In the formula (1), R １ is an arylalkyl group having 7 to 14 carbon atoms, or an aryl group having 6 to 14 carbon atoms. ２ and R ３ R is a hydrogen atom, an oxygen atom, a sulfur atom, an alkyl group having 1 to 12 carbon atoms, or an aryl group having 6 to 14 carbon atoms. ２ or R ３ When is an aryl group, R ２ or R ３ may contain a halogen atom as a substituent.

[0023] In the formula (2), R ４ is a hydrogen atom, a cycloalkyl group having 3 to 12 carbon atoms, or an alkyl group having 1 to 12 carbon atoms. ５ and R ６ are each a hydrogen atom, an oxygen atom, a sulfur atom, an alkyl group having 1 to 12 carbon atoms, or an aryl group having 6 to 14 carbon atoms.

[0024] The glutarimide structural unit (X) is represented by the following formula (3).

[0025] In the formula (3), R ７ and R ８ Each R is, for example, a hydrogen atom or a methyl group. ７ and R ８ may be the same or different. ９ is a hydrogen atom, a methyl group, a butyl group, or a cyclohexyl group. ７ is a methyl group, R ８ is hydrogen, R ９ A combination of methyl groups is preferred.

[0026] The resin is the main component of the base member. Here, "main component" means that the content of the resin in the base member is greater than 50% by mass, where the total mass of the base member is 100% by mass. When the total mass of the base member is 100% by mass, the content of the resin in the base member is preferably 55% by mass or more, more preferably 70% by mass or more, even more preferably 90% by mass or more, and particularly preferably 100% by mass.

[0027] The base member may be a hybrid glass. Hybrid glass is, for example, a synthetic "glass" made from the resin and a silanol compound. The resin may also contain additives, such as commonly used stabilizers. The amount of stabilizer added is preferably 2 parts by mass or more, based on 100 parts by mass of the resin used in the base member, from the viewpoint of effectiveness, and preferably 1 part by mass or less, from the viewpoint of lens transparency.

[0028] The transparent base member (hereinafter also referred to as "the present base member") mainly composed of the resin is molded into a shape having lens functions for use as an in-vehicle lens. Examples of shapes having lens functions include a shape in which both side surfaces are spherical and spherical, or a spherical and flat surface, such as a biconvex lens shape with both sides convex, a plano-convex lens shape with one side convex and one side flat, and a convex meniscus shape with one side convex and one side concave. As will be described later, when the in-vehicle lens is used on the object side of a lens unit, it is preferable to use the convex side on the object side from the viewpoint of resolution, and a plano-convex lens shape or a convex meniscus shape is preferable from the viewpoint of miniaturization of the lens unit and the camera module described later.

[0029] In the vehicle-mounted camera, a hard coat layer and an anti-reflection layer are provided on at least one surface of the base member, the anti-reflection layer being provided on the opposite side of the base member from the hard coat layer, and the anti-reflection layer is covered with a functional film that absorbs ultraviolet light around the edge of the base member (corresponding to the "outer effective diameter region" described below). The hard coat layer and the anti-reflection layer may be provided on either surface of the base member, and when the vehicle-mounted lens is used on the object side of a lens unit, it is preferable that at least one surface of the base member having the hard coat layer and the anti-reflection layer on both sides is the surface facing the object side, from the viewpoint of further suppressing deterioration of the anti-reflection function over long-term use.

[0030] The hard coat layer provided on at least one surface of the base member (hereinafter also referred to as "the hard coat layer") imparts scratch resistance to the lens unit when the in-vehicle lens is used on the object side of a lens unit, and has the effect of improving adhesion between the base member and an antireflection layer described below. For lenses used inside a vehicle, the hard coat layer preferably has a pencil hardness of 5H or more, and for lenses used outside a vehicle, for example, a pencil hardness of 6H or more is more preferable from the viewpoint of scratch resistance due to car washing, etc.

[0031] The hard coat layer preferably comprises a base layer made of an organic material or an organosilicon compound. The hard coat layer preferably comprises a layer in which metal oxide particles are dispersed in the base layer. The metal oxide particles are preferably SiO. ２ , Al ２ O ３ , SnO ２ , TiO ２ and SiO ２ is preferable from the viewpoint of hardness.

[0032] The organic material layer may be made of various resins, and the organosilicon compound layer may be made of, for example, tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetraisopropoxysilane, tetrabutoxysilane, vinyltrialkoxysilane, allyltrialkoxysilane, or acryloxypropyltrialkoxysilane.

[0033] The hard coat layer is usually formed by applying a coating solution containing an organic material or an organosilicon compound that will form the base layer and, if necessary, metal oxide fine particles to the surface of the base member and then drying it. Coating methods include wet processes such as dip coating, spray coating, roll coating, doctor blade coating, spin coating, gravure coating, and screen printing. When forming the hard coat layer, the surface of the base member may be pretreated, such as with an acid or primer, to improve adhesion between the base member and the hard coat layer.

[0034] The coating liquid film formed on the surface of the base member by the above method is cured by heat, electromagnetic waves such as ultraviolet rays, or electron beams. When heat is used, an example method is to apply the coating liquid and then heat-dry it at a temperature of 40°C to 200°C for several hours. The content of metal oxide fine particles in the cured hard coat layer is preferably 25% to 50%. If the content of metal oxide fine particles in the cured hard coat layer is less than 25%, the hardness of the formed hard coat layer may be insufficient. On the other hand, if the content of metal oxide fine particles in the cured hard coat layer is more than 50%, cracks may occur in the hard coat layer.

[0035] The hard coat layer preferably uses a photocurable resin material as the organic material layer. For example, in the hard coat layer formation process, a coating liquid containing a photocurable resin material composed of acrylic and / or urethane and metal oxide fine particles is applied to the surface of the base member by spin coating to form a coating liquid film. If the coating liquid contains water or an organic solvent, as described below, the water or organic solvent is dried to form a coating liquid film. The coating liquid film is then heated and dried, and then photocured using electromagnetic waves such as ultraviolet light or an electron beam to form the hard coat layer. By forming the hard coat layer in this manner by photocuring, the hard coat layer can be formed at a temperature below the glass transition temperature Tg of the base member without the need for heat application. Furthermore, because the hard coat layer is composed of a photocurable resin composed of acrylic and / or urethane, it has excellent adhesion to the base member and functions as an excellent buffer layer between the base member and the anti-reflection layer described below. In the above example, a photocurable resin material is used as the material for the hard coat layer, but the material for the hard coat layer may be a thermosetting resin material instead of a photocurable resin material. In this case, it is preferable to use a thermosetting resin material that heat-cures at a temperature lower than the glass transition temperature Tg of the base member. As the material for the hard coat layer, commercially available Nidek Acier J50PG (Nidek Acier is a registered trademark) is preferably used.

[0036] The preferred application method is spin coating. In spin coating, a coating solution is dropped onto the surface of the base member on which the hard coat layer is to be formed, and then the base member is rotated around the optical axis to form a coating solution film. In order to form a sufficiently thick hard coat layer, it is possible to increase the viscosity of the coating solution. However, increasing the viscosity of the coating solution under conventional application conditions would result in poor uniformity of the coating solution film, and the shape of the vehicle lens would be substantially distorted. Therefore, a coating solution with a relatively high viscosity of 26 mPa·s or more and 50 mPa·s or less is applied, and after dropping the coating solution so that it spreads over the entire surface of the base member, the rotation of the spin coater is controlled. The coating is applied so that the coating solution film is uniform.

[0037] More specifically, in the primary rotation, the rotation speed of the spin coater is gradually accelerated with a predetermined acceleration gradient, then rotated at a constant speed for a certain period of time, and then gradually decelerated with a predetermined deceleration gradient.

[0038] For example, in the primary rotation, the acceleration gradient is set to a range of 100 rpm / s to 3000 rpm / s, the angular velocity during constant rotation is set to a range of 900 rpm to 3000 rpm, and the deceleration gradient is set to a range of 100 rpm to 3000 rpm / s. For example, in the primary rotation, the angular velocity during rotation at a constant speed for a certain period of time is set to 1000 rpm, and the rotation time is set to 10 seconds. Furthermore, the acceleration gradient until the angular velocity reaches 1000 rpm is set to 333 rpm / s, and the deceleration gradient is set to 200 rpm.

[0039] Next, the coating state after the primary rotation is checked, and depending on the check result, a secondary rotation is performed in which the spin coater is rotated at a speed faster than the primary rotation for a certain period of time. In the secondary rotation, as in the primary rotation, the rotation speed of the spin coater is gradually accelerated with a predetermined acceleration gradient, then rotated at a constant speed for a certain period of time, and then gradually decelerated with a predetermined deceleration gradient. More specifically, the angular velocity during the constant rotation is set to at least twice the angular velocity during the primary rotation.

[0040] For example, in the secondary rotation, the angular velocity during rotation at a constant speed for a certain period of time is set to 3000 rpm, the rotation time is set to 9 seconds, the acceleration gradient until the angular velocity reaches 3000 rpm is set to 3000 rpm / s, and the deceleration gradient is set to 600 rpm / s.

[0041] In addition, when a coating film of the coating liquid is formed by performing primary rotation and secondary rotation, the secondary rotation may be configured so that, without decelerating from the uniform rotation speed of the primary rotation, the rotation is gradually accelerated at a predetermined acceleration gradient, then rotated at a constant speed for a certain period of time, and then gradually decelerated at a predetermined deceleration gradient.

[0042] By using the above method, it is possible to thicken the hard coat layer by using a coating solution with a relatively high viscosity of 26 mPa·s or more and 50 mPa·s or less. Furthermore, by setting the conditions of the spin process after dropping the coating solution under the above conditions and making the speed gradient during acceleration and deceleration gentle, sudden acceleration and sudden stopping can be prevented. Therefore, the moment of inertia associated with sudden acceleration and sudden stopping can be reduced, so that even if a sufficiently thick hard coat layer is formed, the thickness of the coating film is less likely to vary.

[0043] The coating solution contains the organic material or organosilicon compound that will form the base layer, and, if necessary, water or an organic solvent that dissolves or disperses metal oxide particles. Examples of organic solvents include acetone, methyl ethyl ketone, pentane, hexane, ethanol, propanol, and isopropanol.

[0044] The thickness of the hard coat layer is preferably 3 μm or more and 20 μm or less. The thickness of the hard coat layer may also vary from the optical axis to the outer edge of the vehicle-mounted lens. For example, the hard coat layer may be formed so that the thickness of the hard coat layer formed on the optical axis of the surface of the base member on which the hard coat layer is formed is approximately 8 μm, and the thickness of the hard coat layer formed on the outer edge of the surface on which the hard coat layer is formed is ±1 μm relative to the thickness of the hard coat layer formed on the optical axis of the surface. By setting the thickness of the hard coat layer within this range, the vehicle-mounted lens can be made to be less susceptible to optical distortion of transmitted light.

[0045] The thickness of the hard coat layer is preferably 5 μm or more from the viewpoint of realizing a pencil hardness of 6H or more. Furthermore, the thickness of the hard coat layer is preferably 10 μm or less from the viewpoint of further suppressing the occurrence of cracks due to thermal shock. From the above viewpoints, the thickness of the hard coat layer is more preferably 6 μm or more and 9 μm or less.

[0046] The in-vehicle lens has an antireflection layer (hereinafter also referred to as "the antireflection layer") provided on at least one surface of the base member. The antireflection layer is provided at least on the surface of the base member on which the hard coat layer is provided, and is provided on the opposite side of the base member from the hard coat layer. The antireflection layer may be provided on the surface of the base member on which the hard coat layer is provided, or may be provided on a surface of the base member on which the hard coat layer is not formed. The provision of the antireflection layer reduces the possibility of ghosts or flares affecting the captured image.

[0047] The antireflection layer is preferably made of a dielectric multilayer film in which low refractive index films and high refractive index films are alternately laminated. For example, the antireflection layer may be made of a silicon dioxide film (SiO ２ film) and trisilicon tetranitride film (Si ３ N ４ Examples of such an antireflection layer include a dielectric multilayer film in which a thin film (a thin film) and a thin film (a thin film) are alternately laminated.

[0048] In the present antireflection layer, the uppermost layer is preferably a silicon dioxide film. Furthermore, the thickness of the uppermost silicon dioxide film is preferably 60 nm or more. Here, the number of layers formed in the present antireflection layer is preferably about 5 or 7, taking into consideration the layer performance and the efficiency of the formation process. Furthermore, from the viewpoint of the antireflection performance of the resulting vehicle-mounted lens, the total thickness of the present antireflection layer is preferably 200 nm or more and 500 nm or less, more preferably 280 nm or more and 500 nm or less.

[0049] If the total thickness of the anti-reflection layer exceeds 500 nm, the stress of the anti-reflection layer may be too high, making the coating more susceptible to cracking, and the temperature of the base member may rise excessively during formation, which may affect the lens surface. Furthermore, if the total thickness of the anti-reflection layer is less than 200 nm, appropriate anti-reflection properties may not be obtained, and the anti-reflection layer may be difficult to maintain its hardness and may be prone to scratches. Furthermore, by optimizing the total thickness of the anti-reflection layer, the temperature rise of the base member during formation of the anti-reflection layer can be suppressed, thereby suppressing changes in the modulation transfer function (MTF). Therefore, high-quality images can be obtained, such as maintaining high resolution.

[0050] It is believed that the in-vehicle lens provided with this antireflection layer exhibits excellent antireflection effects against visible light with wavelengths longer than 420 nm. After forming the antireflection layer, an antifouling layer made of a fluorine-containing silane compound may be formed on the surface of the base member in order to improve the water and oil repellency of the surface. The fluorine-containing silane compound may be dissolved in an organic solvent and applied to the antireflection layer using a water-repellent treatment liquid adjusted to a predetermined concentration.

[0051] The anti-reflection layer is formed by a dry process such as a physical vapor deposition (PVD) method (e.g., vacuum deposition, sputtering, or ion plating) or a chemical vapor deposition (CVD) method on at least the surface of the base member on which the hard coat layer is formed. Sputtering is preferred from the viewpoint of high scratch resistance and abrasion resistance. Furthermore, the anti-reflection layer preferably has an average reflectance of 30.0% or more for ultraviolet light with a wavelength of 315 nm or more and 365 nm or less. To further suppress deterioration of the hard coat layer, the average reflectance is more preferably 70.0% or more. In other words, the anti-reflection layer preferably has an average transmittance of 70.0% or less for ultraviolet light with a wavelength of 315 nm or more and 365 nm or less. To further suppress deterioration of the hard coat layer, the average transmittance of 30.0% or less for ultraviolet light with a wavelength of 315 nm or more and 365 nm or less is more preferably 30.0% or less. In the following description, ultraviolet light having a wavelength of 315 nm or more and 365 nm or less may be simply referred to as ultraviolet light, and the average transmittance and average reflectance for ultraviolet light of this wavelength may be simply referred to as transmittance and reflectance. In one embodiment of the present invention, when the antireflection layer is formed by a sputtering method, the base member is placed in a holder and held from the opposite side of the holder by a cover having a hole slightly smaller than the diameter of the base member. At this time, the diameter of the hole in the cover is usually larger than the effective diameter of the lens. In other words, a portion of the periphery of the edge of the base member is slightly covered by the cover. Because the antireflection layer is formed on the base member held in this state, as described below, in the region outside the effective diameter of the vehicle lens, a portion of the hard coat layer is not covered by the antireflection layer.

[0052] In addition to the hard coat layer and the anti-reflection layer, the in-vehicle lens has an outer-effective-diameter region extending from the lens effective diameter to the edge of the base member, and a functional film that absorbs ultraviolet light (hereinafter also referred to as "the functional film") in the outer-effective-diameter region, and the anti-reflection layer is covered by the functional film in the outer-effective-diameter region. This configuration is thought to suppress deterioration of the hard coat layer when the in-vehicle lens is used over a long period of time, and to suppress deterioration of the anti-reflection function of the in-vehicle lens.

[0053] This functional film has the function of absorbing ultraviolet rays. The ultraviolet absorption function of this functional film preferably has the function of absorbing ultraviolet rays with wavelengths of 315 nm or more and 365 nm or less. Furthermore, the average absorptance of ultraviolet rays with wavelengths of 315 nm or more and 365 nm or less is preferably 98.0% or more per 1 nm of thickness, and more preferably 98.7% or more. In other words, the average ultraviolet transmittance of this functional film is preferably 2.0% or less per 1 nm of thickness, and more preferably 1.3% or less. In the following description, the average absorptance of ultraviolet rays with wavelengths of 315 nm or more and 365 nm or less may be simply referred to as absorptance.

[0054] Materials used in this functional film include, for example, ultraviolet absorbers, light stabilizers, or resins containing at least one of ultraviolet absorbers and light stabilizers. Examples of ultraviolet absorbers include triazine-based compounds, benzotriazole-based compounds, benzophenone-based compounds, salicylate-based compounds, and cyanoacrylate-based materials. Examples of light stabilizers include hindered amine-based compounds. Commercially available ultraviolet absorbers and light stabilizers can be suitably used as these ultraviolet absorbers and light stabilizers.

[0055] Examples of resins containing at least one of an ultraviolet absorber and a light stabilizer include fluorine-based resins, acrylic resins, and urethane resins. Examples of fluorine-based resins include polytetrafluoroethylene (tetrafluoroethylene resin), perfluoroalkoxyalkane (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin), perfluoroethylene propene copolymer (tetrafluoroethylene-hexafluoropropylene copolymer resin), ethylene-tetrafluoroethylene copolymer (tetrafluoroethylene-ethylene copolymer resin), polyvinylidene fluoride (vinylidene fluoride resin), polychlorotrifluoroethylene (trifluorochloroethylene resin), ethylene-chlorotrifluoroethylene copolymer (trifluorochloroethylene-ethylene copolymer resin), tetrafluoroethylene-perfluorodioxole copolymer (tetrafluoroethylene-perfluorodioxole copolymer resin), and polyvinyl fluoride.

[0056] Examples of acrylic resins include polymethyl methacrylate, polyacrylic esters which are copolymers of acrylic esters with methacrylic esters or styrene, sodium polyacrylates obtained by copolymerizing sodium acrylate with acrylic esters or vinyl acetate, polyacrylonitriles obtained by copolymerizing acrylonitrile with acrylic esters, methacrylic esters, and polyacrylamides obtained by hydrolyzing acrylonitrile, and the like.

[0057] Various urethane resins can be obtained by combining an isocyanate with a polyol. Examples of isocyanates include diphenylmethane diisocyanate, tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, naphthalene diisocyanate, and norbornene diisocyanate. Three types of polyols are used: polyether glycol, polyester polyol, and polymer polyol. Examples of polyether polyols include polyether polyols obtained by addition polymerization of epoxy-containing ethylene oxide or propylene oxide using a polyhydric alcohol or amine as an initiator in the presence of a basic catalyst, and polyoxypropylene triols obtained by addition polymerization of propylene oxide with glycerin. Polyester polyols are obtained by dehydration condensation of carboxylic acids and polyhydric alcohols, and examples of the carboxylic acids include adipic acid, phthalic acid, etc., and examples of the polyhydric alcohols include ethylene glycol, 1,4-butanediol, 1,6-hexanediol, etc. Examples of polymer polyols include acrylic polyols, which are acrylic resins obtained by copolymerizing acrylic esters with vinyl compounds, etc., epoxy polyols obtained by amine-modifying or aminoalcohol-modifying bisphenol-type epoxy resins, polyolefin polyols having hydroxyl groups at the terminals of butadiene polymers, copolymers of butadiene with acrylonitrile or styrene, and fluorine-containing polyols obtained by alternating copolymerization of chlorofluoroethylene with vinyl ethers.

[0058] The functional film can be formed, for example, by applying a coating solution prepared by dissolving or dispersing the UV absorber, the light stabilizer, or the resin containing at least one of the UV absorber and the light stabilizer in water or an organic solvent onto the anti-reflection layer and then drying it. The functional film is formed in the outer effective diameter region of the base member, taking into account its effect on the optical performance of the vehicle-mounted lens. However, if the functional film does not affect the optical performance of the lens, the functional film may be formed on the entire surface of the vehicle-mounted lens, i.e., on the anti-reflection layer within the effective diameter region and on the hard coat layer not covered by the anti-reflection layer. In other words, if the functional film does not affect the optical performance of the lens, it is sufficient for the functional film to cover at least a portion of the anti-reflection layer in the outer effective diameter region, and it may be applied to the desired portion of the anti-reflection layer where the functional film is to be formed.

[0059] The coating method may be a spin coating method. One example is a method in which the base member is rotated by a spin coater and the coating solution is applied with a brush. The organic solvent contained in the coating solution may be the same as the organic solvents exemplified for forming the hard coat layer. The thickness of the functional film is preferably 4,000 nm or more and 20,000 nm or less.

[0060] The protective film is formed by applying a coating liquid containing the UV absorber, the light stabilizer, or the resin containing at least one of the UV absorber and the light stabilizer to the desired part of the anti-reflection layer where the functional film is to be formed, and then drying.

[0061] As described above, the hard coat layer and the anti-reflection layer are provided on at least one surface of the base member, the anti-reflection layer is provided on the opposite side of the base member from the hard coat layer, and at least a portion of the anti-reflection layer is covered with the functional film, thereby obtaining the in-vehicle lens.

[0062] In the above-mentioned embodiment, the vehicle-mounted lens may have a layer or film other than the hard coat layer, the antireflection layer, and the functional film. For example, the vehicle-mounted lens may have a water-repellent layer or a protective film described below. Furthermore, a primer layer or an anchor layer may be provided between the hard coat layer and the antireflection layer, or between the antireflection layer and the functional film, in order to enhance adhesion therebetween. The primer layer and the anchor layer can be formed by the same method as exemplified for forming the hard coat layer.

[0063] Examples of embodiments of the in-vehicle lens will be described using Figures 1 and 2. Figure 1 is a schematic diagram of the in-vehicle lens P1, drawn from above. The optical axis of the in-vehicle lens P1 is perpendicular to the paper. Figure 2 is a schematic diagram showing the left half of the A-A' cross section of Figure 1, which passes through the optical axis. Typically, the in-vehicle lens P1 is symmetrical with respect to a plane passing through the optical axis, so only the left half is shown in the following schematic diagram, but the right half is the same as the left half. In Figure 2, the in-vehicle lens 1 has a plano-convex lens shape with one convex side and the other flat side, and the convex side is the object side when used in a lens unit, as described below. The end face of the in-vehicle lens 1 is located between both ends, with the point where the curvature of the spherical surface on the object side of the base member changes being considered as one end and the point from that end to the image-side surface of the base member being considered as another end. The end face of the base member is flat and parallel to the optical axis, but the in-vehicle lens is not limited to this shape. For example, if the base member has a biconvex lens shape, both ends are coincident, so the end faces are the same as the ends. Also, in Figure 2, the hard coat layer 2 is formed directly on the base member 1, extending from the optical axis L to just before the end. Meanwhile, the antireflection layer 3 is formed directly on the hard coat layer 2 and on the opposite side of the base member 1 from the hard coat layer 2.

[0064] As shown in Figure 1, the functional film 4 is formed continuously on the anti-reflection layer 3 along the periphery of the edge, which is the outer effective diameter region of the base member 1 (not shown). Also, in Figure 2, there is a portion where the functional film 4 is formed directly on the hard coat layer 2, and this configuration is preferable from the viewpoint of suppressing cracks in the hard coat layer when the on-vehicle lens is used over a long period of time, and suppressing deterioration of the anti-reflection function of the on-vehicle lens. It is preferable that the functional film 4 cover the edge, including the end face, of the base member 1, as shown in Figure 2.

[0065] The outer effective diameter region of the base member is defined as the region from the lens effective diameter to the edge face, and the functional film covers the anti-reflection layer in the outer effective diameter region. The outer effective diameter region is defined as the region around the edge of the base member, and is defined as the outermost position X ＯＰ The range is from the edge of the lens to the edge surface located in the direction opposite to the optical axis. The effective diameter of the lens is the diameter of the region where the base member ensures the optical function of the lens, and the outermost position of the effective diameter is the position farthest from the optical axis in the region where the base member ensures the optical function of the lens. From the viewpoint of suppressing deterioration of the anti-reflection function of the vehicle lens, as shown in Figure 2, it is preferable that the functional film 4 covers the anti-reflection layer 3 in the outer effective diameter region 6, and it is more preferable that it covers the edge surface. For example, if there is a possibility that the hard coat layer will be exposed at the edge surface, the hard coat layer at the edge surface can also be protected by covering the edge surface with the functional film.

[0066] The fact that the functional film 4 covers the anti-reflection layer 3 in the outer effective diameter region 6 means that the outermost position X ＡＲ is in the outer effective diameter region.

[0067] Furthermore, from the viewpoint of suppressing a decrease in the anti-reflection function of the on-vehicle lens, when the outer effective diameter region is divided into a first region 7 and a second region 8 in this embodiment as shown in Fig. 3, the functional film 4 contacts the anti-reflection layer 3 in the first region 7, and contacts the hard coat layer 2 in the second region 8. In other words, it is preferable that the end of the anti-reflection layer 3 on the opposite side to the optical axis is in the first region 7, and the end of the hard coat layer 2 is in the second region 8. The first region is the outermost position X ＯＰ The functional film 4 is the area where the functional film covers the antireflection layer in the outer effective diameter region in the direction opposite to the optical axis, and the area outside the first area of ​​the outer effective diameter region is the second area. Therefore, the functional film 4 contacts the antireflection layer 3 and the antireflection layer 3 in the first area of ​​the outer effective diameter region, and contacts the hard coat layer 2 outside the area where the antireflection layer 3 is covered in the outer effective diameter region. As described above, when forming an antireflection film by sputtering, the base member is clamped between a holder and a cover. The state in which a portion of the outer effective diameter region of the vehicle lens is covered by the cover may vary depending on the vehicle lens. Therefore, the edge of the antireflection layer also varies depending on the vehicle lens, and the position of the boundary line between the first area, where the functional film covers the antireflection layer, and the second area, where the functional film does not cover the antireflection layer, may vary depending on the vehicle lens. Furthermore, the center of the hole in the cover may not necessarily coincide with the center (optical axis) of the clamped lens. Therefore, the position of the boundary line between the first region and the second region may vary along the circumference of the lens even within the same vehicle-mounted lens.

[0068] The in-vehicle lens may have a water-repellent layer in addition to the hard coat layer, anti-reflection layer, and functional film. The water-repellent layer is a thin film that is water-repellent, and preferably has a contact angle of a water droplet of 90 degrees or more. The contact angle is measured using the sessile drop method (half-angle method), in which a 2.5 microliter water droplet is dropped onto the surface of the base member on which the water-repellent layer is formed, and the curved surface connecting the left and right endpoints of the droplet is considered to be a straight line, and the contact angle of the water droplet is measured. The provision of a water-repellent layer prevents water droplets adhering to the surface of the in-vehicle lens from accumulating, thereby further suppressing degradation of image quality caused by water droplets on the lens surface.

[0069] The water-repellent layer typically uses a fluorine compound or a fluorine-based resin. Examples of fluorine compounds include perfluorooctanecarboxylic acid and perfluorooctanoic acid. Examples of fluorine-based resins include polytetrafluoroethylene (tetrafluoroethylene resin), perfluoroalkoxyalkane (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin), perfluoroethylenepropene copolymer (tetrafluoroethylene-hexafluoropropylene copolymer resin), ethylene-tetrafluoroethylene copolymer (tetrafluoroethylene-ethylene copolymer resin), polyvinylidene fluoride (vinylidene fluoride resin), polychlorotrifluoroethylene (trifluorochloroethylene resin), ethylene-chlorotrifluoroethylene copolymer (trifluorochloroethylene-ethylene copolymer resin), tetrafluoroethylene-perfluorodioxole copolymer (tetrafluoroethylene-perfluorodioxole copolymer resin), and polyvinyl fluoride. The commercially available Daikin Optool UD120 (Daikin Optool is a registered trademark) is a suitable material for the water-repellent layer.

[0070] The water-repellent layer can be prepared by applying a coating solution prepared by dissolving or dispersing the fluorine compound or fluorine-based resin in water or an organic solvent, followed by drying. The coating method can be the same as that for preparing the hard coat layer, and the organic solvent used in the coating solution can be the same as that described above.

[0071] When the vehicle-mounted lens has the water-repellent layer, the thickness of the water-repellent layer is preferably 20 nm or more and 100 nm or less.

[0072] When the vehicle-mounted lens has the water-repellent layer, the water-repellent layer is preferably provided on the antireflection layer. When the water-repellent layer is provided on the antireflection layer, the water-repellent layer may be provided directly on the antireflection layer, or, for example, a primer layer may be provided on the antireflection layer, and the water-repellent layer may be provided on the primer layer in order to improve adhesion between the water-repellent layer and the antireflection layer.

[0073] When the vehicle-mounted lens has the water-repellent layer, it is preferable that the water-repellent layer 9 is provided directly on the anti-reflection layer 3, covering the anti-reflection layer 3 within the effective diameter region, as shown in Figure 4. Note that the effective diameter region is the range from the lens effective diameter of the base member to the optical axis. In Figure 4, the water-repellent layer 9 covers the entire surface of the anti-reflection layer 3 within the effective diameter region, but it does not necessarily have to cover the entire surface, as long as it covers at least a portion of the effective diameter region of the anti-reflection layer 3.

[0074] Furthermore, the water-repellent layer 9 does not need to cover the edge of the anti-reflection layer 3, and may cover the edge of the functional film provided on the anti-reflection layer as shown in Fig. 4, or the water-repellent layer 9 may be covered by the functional film 4, with the water-repellent layer 9 provided between the anti-reflection layer 3 and the functional film 4 as shown in Fig. 5. When the water-repellent layer 9 is provided between the anti-reflection layer 3 and the functional film 4, the edge of the water-repellent layer 9 is preferably in the region outside the effective diameter, and more preferably in the second region, as shown in Fig. 5.

[0075] It is preferable that the functional film has an elastic function in addition to the function of absorbing ultraviolet rays. That is, as described above, the functional film is more preferably an elastic body containing a resin material such as a fluorine-based resin, an acrylic resin, and / or a urethane-based resin. By having the elastic function, the functional film can also play a role in protecting the crimped portion that faces the crimping portion for fixing the in-vehicle lens when the in-vehicle lens described below is made into a lens unit and stored in a lens barrel. For the above reasons, it is preferable that the functional film has an elastic function so as to be able to absorb stress from the crimping portion.

[0076] In another embodiment, an elastic protective film may be added under the functional film. That is, in another embodiment, the functional film may be divided into two films: one that absorbs ultraviolet light and one that is an elastic film that absorbs stress caused by the crimped portion. In this case, the protective film is preferably provided under the functional film, i.e., between the functional film and the base member, in a location corresponding to the crimped portion facing the crimped portion. For example, as shown in Figure 6, the protective film 11 may be provided so as to cover only the area corresponding to the crimped portion.

[0077] The material of the protective film provides elasticity, and examples thereof include fluoropolymer resin, urethane resin, and acrylic resin.

[0078] The method for forming the protective film is the same as the method for forming the functional film, and after forming the protective film, the functional film is formed using the same method. When the vehicle-mounted lens has the protective film, it can be formed on the base member, for example, on the end surface of the base member, using the above method, and then the functional film can be formed using the above method, thereby forming the protective film at the desired location.

[0079] As described above, the on-vehicle lens exhibits reduced deterioration in its anti-reflection function even over long periods of use. Therefore, the on-vehicle lens can be suitably used as a lens unit (hereinafter also referred to as the "on-vehicle lens unit") in combination with at least one other lens. When the on-vehicle lens is used as the on-vehicle lens unit, an example embodiment is shown in FIG. 7 , in which the on-vehicle lens P1, with the surface of the base member 1 on which the hard coat layer 2 and the anti-reflection layer 3 are provided, is the outermost lens, and the on-vehicle lens P1 is combined with at least one other lens P3 on the image side. In FIG. 7 , a lens group P2 composed of multiple lenses may be provided between the on-vehicle lens P1 and the lens P3. The lenses constituting the lens group P2 composed of multiple lenses can be of various shapes, depending on the purpose of the camera module including the on-vehicle lens unit (described later). The on-vehicle lens P1, the lenses constituting the lens group P2 composed of multiple lenses, and the lens P3 are combined so that their optical axes L coincide.

[0080] When the in-vehicle lens is used as the outermost lens, the hard coat layer, the antireflection layer, the functional film, and the water-repellent layer provided on the base member have the same configurations and positions as described above, and the preferred embodiments are also as described above.

[0081] The lens unit of Figure 7 has the vehicle-mounted lens P1 as the outermost lens on the object side, and has a lens barrel 12 on the image side that houses at least one lens P3 and a lens group P2 that combines multiple lenses between the outermost lens and lens P3.

[0082] The lens barrel 12 preferably has a crimped portion 13 for fixing the in-vehicle lens P1 to the object-side end of the lens barrel 12. The crimped portion may be formed along the entire inner circumferential surface of the lens barrel 12, or may be formed on a part of the inner circumferential surface. It is preferable that an O-ring or the like is provided as a sealing member between the outer circumferential surfaces of the in-vehicle lens P1, lens P3, and each of the lenses constituting the lens group P2 and the inner circumferential surface of the lens barrel 12, thereby sealing the gap between the outer circumferential surface of each lens and the inner circumferential surface of the lens barrel 12.

[0083] When the in-vehicle lens P1 is the outermost lens on the object side, as described above, the outer effective diameter region is defined as the region from the lens effective diameter of the outermost lens to the edge, and it is preferable that the crimped portion facing the crimping portion is located in this outer effective diameter region. As shown in Figure 7, the crimped portion preferably has a crimped portion 14 located in the outer effective diameter region 6. If a protective film is provided separately from the functional film, it is preferable that the crimped portion is covered with a protective film (not shown) as shown in Figure 7, and the functional film 4 is provided on top of the protective film.

[0084] Since the anti-reflection function of this lens unit is prevented from deteriorating over long periods of use, a camera module having this lens unit (hereinafter also referred to as "this camera module") is suitable for use as an in-vehicle camera module. This camera module typically includes this lens unit, an image sensor, a substrate, and an image signal processor.

[0085] The camera module exhibits reduced deterioration in its anti-reflection function even when used over a long period of time in harsh environments with large temperature differences, making it suitable for use as an in-vehicle camera such as an image recognition camera or a recording camera that is used over a long period of time in such harsh environments.

[0086] The method for manufacturing an on-vehicle lens of the present invention (hereinafter also referred to as "the manufacturing method") includes a first step of forming a hard coat layer on a transparent base member containing a resin as a main component, a second step of forming an anti-reflection layer on the hard coat layer formed in the first step, and a third step of forming a functional film that absorbs ultraviolet light in an outer-effective-diameter region that extends from the lens effective diameter to the edge of the base member. In the manufacturing method, the hard coat layer, the anti-reflection layer, and the functional film are the same as those exemplified and preferred examples of the hard coat layer, the anti-reflection layer, and the functional film, and the first step, second step, and third step are the same as the methods for forming the hard coat layer, the anti-reflection layer, and the functional film, and the preferred embodiments are also the same.

[0087] The in-vehicle lens, the in-vehicle lens unit, and the in-vehicle camera module have been described above, but the present invention is not limited to the configurations of the above-described embodiments. The in-vehicle lens, the in-vehicle lens unit, and the in-vehicle camera module may have any other configuration added to the configurations of the above-described embodiments, or may be replaced with any other configuration that provides a similar function. Furthermore, the in-vehicle lens, the in-vehicle lens unit, and the in-vehicle camera module may have any other step added to the steps of the above-described embodiments, or may be replaced with any other step that provides a similar effect.

[0088] The present invention will be described in detail below with reference to examples, but is not limited to these. In the examples, the following base member, hard coat layer, anti-reflection layer, functional film and water-repellent layer were used.

[0089] <Base Member A> A low birefringence transparent resin AZP (registered trademark) (manufactured by Asahi Kasei Corporation) was used.

[0090] <Hard Coat Layer A> A hard coat layer was formed by spin coating using Nidek Acier J50PG (manufactured by Nidek Co., Ltd., Nidek Acier is a registered trademark) which is a mixed solution of urethane and amorphous silica and has a solid content of 56.2%, followed by UV curing. The content of metal oxide fine particles in the cured hard coat layer was 27%.

[0091] <Anti-reflection layer A> Eight layers of silicon dioxide as low refractive index layers and trisilicon tetranitride as high refractive index layers were alternately laminated, with the high refractive index layers and low refractive index layers being the outermost layers (the side opposite to the base member). The lamination was performed using a Shincron RAS1100C (manufactured by Shincron Co., Ltd.) by Radical Assisted Sputtering (RAS).

[0092] <Functional Film> Functional Film A: A functional film was formed by spin coating using F-200I, the original solution of Jet Protector F-200SI, a one-component product manufactured by Taihei Kasei Co., Ltd. Functional Film B: A functional film was formed by spin coating using F-3000, a two-component product manufactured by Taihei Kasei Co., Ltd. As shown in Figure 8, the average transmittance of ultraviolet light with a wavelength of 315 nm or more and 365 nm or less was 1.3% for Functional Film A and 1.2% for Functional Film B.

[0093] <Water-repellent layer A> The water-repellent layer A was formed by vapor deposition using Daikin Optool UD120 (manufactured by Daikin Corporation, Daikin Optool is a registered trademark).

[0094] [Weather resistance evaluation] Weather resistance was evaluated as follows. A durability test was carried out using a 7.5 kW super xenon weather meter as a highly accelerated weather resistance tester. The irradiance was 180 W / m ２ The test was carried out for 500 cycles, with one cycle consisting of 18 minutes of irradiation and rainfall, followed by 102 minutes of irradiation. After the test, samples with no damage to the anti-reflection film were marked with a circle, and samples with damage to the anti-reflection film were marked with an X.

[0095] Example 1: An in-vehicle lens A was fabricated using the base member A described above as a base member. A hard coat layer A, an anti-reflection layer A, a water-repellent layer A, and a functional film A were formed on the base member A in the layer configuration shown in Figure 5. First, the hard coat layer A was formed by cleaning the surface of the base member A and then placing it in a spin coater. In this state, approximately 70 μL of the coating solution was dropped onto the lens surface, and the lens was then rotated. After being transferred from the spin coater to a vacuum dryer, the lens was dried at a set temperature of 80°C for 30 minutes, and then irradiated with ultraviolet light for 30 seconds to perform UV curing. Next, the base member A on which the hard coat layer A was formed was placed in a sputtering device. The sputtering device was set to repeat the process of alternately depositing high-refractive index layers and low-refractive index layers four times, and then the sputtering process was initiated. In the anti-reflection film thus formed, the outermost layer was a low-refractive index layer. The water-repellent layer A was formed in the same sputtering device after the anti-reflection layer A was formed. Next, the functional film was formed by spinning the base member A on which each layer and functional film had been formed as described above in a spin coater, while the liquid described in the functional film A was applied with a brush. The base member A was then placed in a preheated oven and dried by heating at a set temperature of 80°C for 60 minutes. As a result of forming the functional film using the above process, the thicknesses of the hard coat layer, anti-reflection layer, water-repellent layer, and functional film were 8±0.5 μm, 424 nm, 4000 nm to 20000 nm, and 20 nm to 100 nm, respectively. The weather resistance of the in-vehicle lens A was evaluated using the above method, and was rated as good.

[0096] Example 2 An in-vehicle lens P1 was produced by forming a hard coat layer A, an anti-reflection layer A, a water-repellent layer A, and a functional film B on a base member 1 so as to have the layer structure shown in Figure 5. The hard coat layer A, the anti-reflection layer A, and the water-repellent layer A were produced using the same procedures as in Example 1. In Example 2, the functional film was produced under the same conditions as in Example 1, except that the liquid described above for functional film B was used. The thicknesses of the hard coat layer, the anti-reflection layer, the functional film, and the water-repellent layer were 8±0.5 μm, 424 nm, 4000 nm to 20000 nm, and 20 nm to 100 nm, respectively. The weather resistance of in-vehicle lens B was evaluated and rated as good.

[0097] <Comparative Example 1> An on-vehicle lens C was produced in the same manner as in Example 1, except that no functional film was used. The weather resistance of on-vehicle lens C was evaluated and the result was X. <Example 3> The ultraviolet transmittance of the antireflection layer was adjusted by applying a material obtained by adding an acrylic resin to the material of the functional film of Example 1 to the surface of the antireflection layer, and the ultraviolet transmittance of the antireflection layer within the effective diameter was set to 70.0%. The weather resistance of on-vehicle lens D, on which an antireflection layer with an adjusted transmittance was formed, was evaluated and the result was O.

[0098] As is clear from the above results, the provision of the functional film prevented damage to the anti-reflection layer even after the weather resistance evaluation after high acceleration. Therefore, it is believed that the degradation of the anti-reflection function of this vehicle lens is suppressed even with long-term use. Furthermore, since the average transmittance of the anti-reflection layer in both Examples 1 and 2 was set to 70% or less, ultraviolet degradation of the hard coat layer not covered by the anti-reflection layer can be appropriately prevented. If the functional film also had water-repellent properties, it is believed that the vehicle lens could appropriately repel water droplets at its outer periphery. This is believed to further reduce the impact of water droplets on captured images. In particular, in Example 1, in which a water-repellent layer is formed on the anti-reflection layer, water droplets are repelled from the entire surface of the vehicle lens, thereby minimizing the difference in water-repellent performance between the optical axis and the edge of the lens. In other examples, when an inflection point is present on the surface of the vehicle lens, the edge periphery of the base member may refer to the region from the edge of the lens to the inflection point on the lens surface and the edge surface of the base member. In this case, the functional film is configured to cover the inflection point as well.

[0099] As explained above, the present specification discloses the following: [1] An on-vehicle lens having a transparent base member mainly composed of resin, wherein a hard coat layer and an anti-reflection layer are provided on at least one surface of the base member, the anti-reflection layer is provided on the opposite side of the hard coat layer from the base member, an outer effective diameter region extends from the lens effective diameter to an edge of the base member, and the anti-reflection layer is covered in the outer effective diameter region with a functional film that absorbs ultraviolet light.

[0100] By adopting the above-mentioned configuration, deterioration of the anti-reflection function of the in-vehicle lens is suppressed even when the lens is used for a long period of time.

[0101] [2] The in-vehicle lens according to [1], wherein the functional film has an ultraviolet transmittance equal to or less than that of the anti-reflection layer. [3] The in-vehicle lens according to [2], wherein the anti-reflection layer has an ultraviolet transmittance of 70% or less.

[0102] [4] The on-vehicle lens according to any one of [1] to [3], wherein the functional film includes a first area on the optical axis side and a second area on the edge side in the radial direction of the outer effective diameter region, and the functional film contacts the anti-reflection layer in the first area and the hard coat layer in the second area in the outer effective diameter region. [5] The on-vehicle lens according to any one of [1] to [4], wherein the effective diameter region is defined as the distance from the lens effective diameter of the base member to the optical axis of the base member, and a water-repellent layer is provided on the anti-reflection layer in the outer effective diameter region. [6] The on-vehicle lens according to any one of [1] to [5], wherein the water-repellent layer is provided between the anti-reflection layer and the functional film in the outer effective diameter region. [7] The on-vehicle lens according to any one of [1] to [6], wherein the functional film further has a water-repellent function.

[0103] The present invention further has the following aspects. [8] A lens unit having an on-vehicle lens according to any one of [1] to [7] above as its outermost lens and having at least one lens other than the outermost lens. [9] The lens unit according to [8] above, having a lens barrel that houses the outermost lens and the at least one lens, the lens barrel having a crimping portion for fixing the outermost lens.

[10] The lens unit according to [9] above, having an outer effective diameter region extending from the lens effective diameter to an edge of the outermost lens, the outer effective diameter region of the outermost lens having a crimped portion facing the crimping portion, the functional film being an elastic body containing an organic material, and the crimped portion being covered with the functional film that is the elastic body.

[11] A camera module having the lens unit according to any one of [8] to

[10] above.

[0104] The present invention also has the following aspect:

[12] A method for manufacturing a lens, comprising: a first step of forming a hard coating layer on a transparent base member containing a resin as a main component, a second step of forming an anti-reflection layer on the hard coating layer formed in the first step, and a third step of forming a functional film that absorbs ultraviolet light so that an outer-effective-diameter region extends from the lens effective diameter to an edge of the base member, and the anti-reflection layer is covered in the outer-effective-diameter region.

[0105] P1: This vehicle-mounted lens, P2: Lens group combining multiple lenses, P3: Other lenses, L: Optical axis, X ＯＰ : outermost position of the lens effective diameter, X ＡＲ : Outermost position of anti-reflection film, 1: Base member, 2: Hard coat layer, 3: Anti-reflection layer, 4: Functional film, 5: Edge of base member, 5': End of base member, 6: Area outside effective diameter, 7: First area, 8: Second area, 9: Water-repellent layer, 10: Inside effective diameter area, 11: Protective film, 12: Lens barrel, 13: Caulking portion, 14: Caulked portion

Claims

1. An on-vehicle lens having a transparent base member mainly composed of resin, wherein a hard coat layer and an anti-reflection layer are provided on at least one surface of the base member, the anti-reflection layer is provided on the opposite side of the base member from the hard coat layer, an outer effective diameter region is defined as a region from the lens effective diameter to the edge of the base member, and in the outer effective diameter region, the anti-reflection layer is covered with a functional film that absorbs ultraviolet light.

2. The vehicle-mounted lens according to claim 1, wherein the functional film has an ultraviolet ray transmittance equal to or lower than that of the anti-reflection layer.

3. The vehicle-mounted lens according to claim 2, wherein the anti-reflection layer has an ultraviolet ray transmittance of 70% or less.

4. The vehicle-mounted lens according to claim 1, wherein the functional film includes a first area on the optical axis side and a second area on the edge side in the radial direction of the outer effective diameter region, and the functional film contacts an anti-reflection layer in the first area and contacts a hard coat layer in the second area in the outer effective diameter region.

5. The vehicle-mounted lens according to claim 1, wherein an effective diameter area is defined as a region from the lens effective diameter in the base member to the optical axis of the base member, and a water-repellent layer is provided on the anti-reflection layer within the effective diameter area.

6. The vehicle-mounted lens according to claim 5, wherein in the outer effective diameter region, the water-repellent layer is provided between the anti-reflection layer and the functional film.

7. The vehicle-mounted lens according to claim 1 or 5, wherein the functional film further has a water-repellent function.

8. A lens unit having the on-vehicle lens according to claim 1 as an outermost lens, and having at least one lens other than said outermost lens.

9. The lens unit according to claim 8, further comprising a lens barrel that houses said outermost lens and said at least one lens, said lens barrel having a caulking portion for fixing said outermost lens.

10. A lens unit as described in claim 9, wherein the region from the lens effective diameter of the outermost lens to its edge is an outer effective diameter region, the outer effective diameter region of the outermost lens has a crimped portion facing the crimping portion, the functional film is an elastic body containing an organic material, and the crimped portion is covered with the functional film which is the elastic body.

11. A camera module having a lens unit according to any one of claims 8 to 10.

12. A method for manufacturing a lens, comprising: a first step of forming a hard coat layer on a transparent base member containing a resin as a main component; a second step of forming an anti-reflection layer on the hard coat layer formed in the first step; and a third step of forming a film so that the region from the effective diameter of the lens in the base member to the edge is defined as an outer effective diameter region, and the anti-reflection layer is covered in the outer effective diameter region with a functional film that absorbs ultraviolet light.

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