Lens unit and method for manufacturing lens unit

Abstract

Provided is a lens unit comprising a plurality of lenses and a cylindrical accommodating member that accommodates the plurality of lenses therein, the accommodating member having a crimping part, and an outermost lens positioned on an opening side of the accommodating member from among the plurality of lenses being fixed by the crimping part, wherein the outermost lens has a crimped part that comes into contact with the crimping part, the outermost lens is provided with an antireflection film on at least the object-side surface of the outermost lens, and the expression Xc > Xar is satisfied, where Xar is the position of the outer periphery of the antireflection film in the radial direction with the optical axis of the outermost lens as the origin point, and Xc is the position of the crimped part of the outermost lens.

Description

Lens unit and manufacturing method thereof

[0001] The technology of the present disclosure relates to a lens unit and a method for manufacturing the lens unit.

[0002] Patent Document 1 discloses a lens unit including a lens barrel and a plurality of lenses arranged within the interior storage space of the lens barrel. The outermost lens, which is located closest to the object among the plurality of lenses, is provided with a highly heat-resistant anti-reflection coating over the entire surface of the lens facing the object side. A crimped portion is provided at the object-side end of the lens barrel. The outermost lens is fixed to the object-side end of the lens barrel by thermoplastically deforming (crimping) this crimped portion toward the optical axis.

[0003] JP 2023-073340 A

[0004] In the lens unit of Patent Document 1, for purposes such as simplifying the manufacturing process and reducing costs, a configuration without a protective film on the anti-reflection film is conceivable, even for use in an in-vehicle camera. If a protective film is not provided on the anti-reflection film of such a lens unit, it is conceivable to increase the volume fraction of inorganic particles in the anti-reflection film or to increase the Young's modulus of the binder in order to improve the scratch resistance of the lens surface facing the object side of the outermost lens. However, such a configuration reduces the flexibility of the anti-reflection film, and therefore, when the lens is fixed to the lens barrel with the crimped portion, stress on the anti-reflection film generated when the crimped portion is crimped may cause defects such as cracks where the crimped portion strongly hits the anti-reflection film.

[0005] The technology of the present disclosure has been developed in consideration of the above facts, and aims to provide a lens unit and a method for manufacturing the lens unit that can prevent defects from occurring in the anti-reflection coating provided on the object-side surface of the outermost lens, even if the object-side end of a cylindrical housing member that houses multiple lenses is crimped.

[0006] In order to achieve the above object, a first aspect of the technology of the present disclosure is a lens unit including a plurality of lenses and a cylindrical housing member that houses the plurality of lenses therein, the housing member having a crimping portion, an outermost lens of the plurality of lenses that is located on the opening side of the housing member being fixed by the crimping portion, the outermost lens having a crimped portion that comes into contact with the crimping portion, the outermost lens having an anti-reflection coating on at least the object-side surface of the outermost lens, and in a radial direction with the optical axis of the outermost lens as the origin, when the position of the outer periphery of the anti-reflection coating is Xar and the position of the crimped portion of the outermost lens is Xc, the following mathematical formula is established: Xc>Xar (1)

[0007] A second aspect is a manufacturing method of a lens unit including a plurality of lenses and a cylindrical housing member that houses the plurality of lenses therein, the method including: providing an anti-reflection film on at least the object-side surface of an outermost lens of the plurality of lenses that is located on the opening side of the housing member; and crimping the object-side end of the housing member to the outermost lens so as to hold the outermost lens after the anti-reflection film has been provided, wherein by crimping the object-side end of the housing member to the outermost lens, the housing member has a crimped portion and the outermost lens has a crimped portion that contacts the crimped portion, and the anti-reflection film is provided so that the following mathematical formula is established: Xc>Xar (1)

[0008] A third aspect is a lens unit that includes a plurality of lenses and a cylindrical housing member that houses the plurality of lenses therein, and an object-side end of the housing member is crimped to the outermost lens so as to hold the outermost lens of the plurality of lenses that is located on the opening side of the housing member, and by crimping the object-side end of the housing member to the outermost lens, the housing member has a crimping portion and the outermost lens has a crimped portion that comes into contact with the crimping portion, and an anti-reflection film is provided on the object-side surface of the outermost lens to which the object-side end of the housing member is crimped so that the following mathematical formula is established: Xc>Xar (1)

[0009] The technique of the present disclosure can prevent defects from occurring in the anti-reflection coating provided on the object-side surface of the outermost lens.

[0010] FIG. 1 is a cross-sectional view showing an example of a lens unit having an on-vehicle lens according to a first embodiment; FIG. 2 is a diagram showing an example of the lens unit according to the first embodiment, in which the position of the outer periphery of the anti-reflection film is located closer to the optical axis than the position of the portion that comes into contact with the outermost lens when the object-side end of the holding member is crimped; FIG. 3 is a diagram showing an example of a process for forming an anti-reflection film on the outermost lens; FIG. 4 is a diagram showing the state of the outermost lens before the object-side end of the holding member is crimped in the prior art; FIG. 5 is a diagram showing the relationship between the position of the outer periphery of the anti-reflection film and the position of the portion that comes into contact with the outermost lens when the object-side end of the holding member is crimped in the prior art; FIG. 6 is a diagram showing an example of the state of the outermost lens before the object-side end of the holding member is crimped in the first embodiment; FIG. 7 is a diagram showing an example of the relationship between the position of the outer periphery of the anti-reflection film and the position of the portion that comes into contact with the outermost lens when the object-side end of the holding member is crimped in the first embodiment; 10 is a diagram showing an example in which the position of the outer periphery of the anti-reflection film is located closer to the optical axis than the position of the portion that contacts the outermost lens by crimping the object-side end of the housing member in the lens unit of the second embodiment. FIG. 11 is a diagram showing a process of arranging a hard coat layer and an anti-reflection film on the outermost lens. FIG. 12 is a cross-sectional view showing an example of a lens unit having an on-vehicle lens of the third embodiment. FIG. 13 is a diagram showing an example of the state of the outermost lens before the object-side end of the housing member of the third embodiment is crimped. FIG. 14 is a diagram showing an example of the state of the outermost lens after the object-side end of the housing member of the third embodiment is crimped. FIG. 15 is a diagram showing a state in which an anti-reflection film is formed on the outermost lens after the object-side end of the housing member of the third embodiment is crimped. FIG. 16 is a diagram showing an example of the state in which an anti-reflection film and a water-repellent layer are arranged on the outermost lens of the fourth embodiment.

[0011] The technology of the present disclosure will be described below with reference to the drawings.

[0012] [First embodiment] Fig. 1 is a cross-sectional view showing an example of a lens unit 10A having an on-vehicle lens according to a first embodiment. Fig. 2 is a diagram showing an example of the lens unit 10A according to the first embodiment, in which the outer periphery of the anti-reflection film is positioned closer to the optical axis L than the portion that contacts the outermost lens P1 due to the object-side end of the housing member 12 being crimped.

[0013] As shown in FIG. 1, the lens unit 10A includes a plurality of lenses P1, P2, a filter F1, and a cylindrical housing member 12 that houses the plurality of lenses P1, P2 and the filter F1 therein.

[0014] The lenses P1 and P2 are glass lenses. Lens P2 includes multiple lenses, but is illustrated as a single member in Fig. 1 and other figures for simplicity. Filter F1 is a glass filter, such as an infrared cut filter that cuts infrared rays. In other embodiments, filter F1 may be positioned in the optical axis direction by a housing member 12.

[0015] The housing member 12 contains a thermoplastic resin material. Possible materials for the housing member 12 include crystalline plastics with excellent weather resistance and amorphous plastics with relatively low moisture absorption. Examples of crystalline plastics include polyethylene, polyamide, and polytetrafluoroethylene. Examples of amorphous plastics include polycarbonate. In this embodiment, since the lens unit is installed outside the vehicle, crystalline plastics are used in consideration of weather resistance. In particular, the use of polyamide allows the housing member 12 to have excellent weather resistance. The housing member 12 is also sometimes called a lens barrel or lens barrel.

[0016] The housing member 12 of the lens unit 10A has a caulking portion 4. The outermost lens P1, which is located on the opening side of the housing member 12 among the plurality of lenses P1 and P2, is fixed by the caulking portion 4.

[0017] The outermost lens P1 has a crimped portion 5 that comes into contact with the crimping portion 4. The outermost lens P1 has an anti-reflection film (AR film) 2 on the object side surface of the outermost lens P1.

[0018] 2, in the lens unit 10A, when the position of the outer periphery of the anti-reflection coating 2 in the radial direction R with the optical axis L of the outermost lens P1 as the origin is defined as Xar and the position of the crimped portion 5 of the outermost lens P1 is defined as Xc, the following formula is established: Xc>Xar (1)

[0019] The anti-reflection coating 2 covers at least the effective lens surface sv of the outermost lens P1.

[0020] In the lens unit 10A, when the end position of the lens effective surface sv in the radial direction with the optical axis L of the outermost lens P1 as the origin is defined as Xop, the following formula is established: Xar>Xop (2)

[0021] The following equation is obtained from equations (1) and (2): Therefore, in the lens unit 10A, the following equation (12) holds: Xc>Xar>Xop (12)

[0022] Next, a method for manufacturing the lens unit 10A will be described.

[0023] The manufacturing method of the lens unit 10A includes a step of providing an anti-reflection coating 2 on at least the object-side surface of the outermost lens P1, which is located on the opening side of the housing member 12 among the multiple lenses P1 and P2.

[0024] FIG. 3 is a diagram showing an example of a process for forming an anti-reflection film on the outermost lens P1.

[0025] The outermost lens P1 is placed on a fixing jig (base) t1, and the outermost lens P1 is fixed with a fixing jig (cover) t2 (T1).

[0026] An anti-reflection coating 2 is formed on the surface of the fixed outermost lens P1 by a dry process. For example, vaporized molecules are deposited to form a thin film coating (T2). This forms an anti-reflection coating (AR coating) 2 on the outermost lens P1 (T3).

[0027] The anti-reflection film 2 has a multi-layer structure in which high-refractive index layers and low-refractive index layers are alternately stacked, and these high-refractive index layers and low-refractive index layers contain inorganic materials. As an example, the anti-reflection film 2 may have a multi-layer structure in which high-refractive index layers and low-refractive index layers are alternately stacked in a total of eight layers. The layer closest to the object side in the multi-layer structure is a low-refractive index layer. The high-refractive index layer may be made of, for example, silicon tetranitride (Si ３ N ４ The low refractive index layer is, for example, silicon dioxide (SiO ２ In other embodiments of the antireflection coating, the total number of high-refractive-index layers and low-refractive-index layers may be more or less than eight. In addition, the layer closest to the object side in the multilayer structure may be the high-refractive-index layer.

[0028] The manufacturing method of lens unit 10A also includes a step of crimping the object-side end of housing member 12 to outermost lens P1 so as to hold outermost lens P1 after anti-reflection coating 2 is provided. Specifically, crimped portion 4 on the object side of housing member 12 is deformed toward the optical axis when heat is applied. That is, crimped portion 4, which is the object-side end of housing member 12, is thermally crimped and thermoplastically deformed.

[0029] By crimping the object side end (crimping portion 4) of the housing member 12 to the outermost lens P1, the housing member 12 has the crimping portion 4 and the outermost lens P1 has a crimped portion 5 that contacts the crimping portion 4.

[0030] The position Xar of the outer periphery of the anti-reflection coating 2 is set based on the thickness of the anti-reflection coating 2 and the distance between the surface of the crimped portion 4 facing the outermost lens P1 and the object-side surface of the outermost lens P1 so that equations (1), (2), and (12) hold.

[0031] The position Xar of the outer periphery of the anti-reflection coating 2 is determined by a fixing jig (cover) t2 used when forming the anti-reflection coating 2 on the lens P1. For example, the fixing jig is a jig having one or more circular holes. The diameter of the circular holes is smaller than the diameter of the lens P1. When the anti-reflection coating 2 is formed on the lens P1, the peripheral edge of the lens P1 is covered by the fixing jig (cover) t2. As a result, the anti-reflection coating 2 is not formed on the peripheral edge of the lens P1. In this embodiment, the position Xar of the outer periphery of the anti-reflection coating 2 can be adjusted by adjusting the distance over which the fixing jig (cover) t2 covers the lens P1, i.e., the distance over which the end of the fixing jig (cover) t2 extends toward the optical axis.

[0032] In the step of providing the anti-reflection coating 2, the anti-reflection coating 2 is provided so that the formulas (1), (2), and (12) are satisfied. Therefore, the outer periphery of the anti-reflection coating 2 is located closer to the optical axis L than the position of the crimped portion 5 of the outermost lens P1.

[0033] Fig. 4A is a cross-sectional view showing the state of the outermost lens P1 in the prior art before the object-side end of the housing member 12 is crimped. Fig. 4B is a cross-sectional view showing the relationship between the position of the outer periphery of the anti-reflection coating and the position of the portion that comes into contact with the outermost lens P1 after the object-side end of the housing member 12 is crimped.

[0034] Conventionally, when the object side end of the housing member 12 is crimped to the outermost lens P1, the anti-reflection coating 2 is located between the crimped portion 4 of the housing member 12 and the outermost lens P1 when viewed from the cross-sectional direction. Specifically, when viewed from the optical axis direction, the position Xar of the outer periphery of the anti-reflection coating 2 is located closer to the lens outer periphery than the position Xc of the crimped portion 5 of the outermost lens P1. In this case, for example, the stress caused by thermal crimping can cause the anti-reflection coating 2 to crack.

[0035] Fig. 5A is a cross-sectional view showing an example of the state of the outermost lens P1 before the object-side end of the housing member 12 is crimped in the first embodiment. Fig. 5B is a cross-sectional view showing an example of the relationship between the position of the outer periphery of the anti-reflection film and the position of the portion that comes into contact with the outermost lens P1 after the object-side end of the housing member 12 is crimped in the first embodiment.

[0036] In contrast, in the present embodiment, in the step of providing the antireflection coating 2, the antireflection coating 2 is provided so that the formulas (1), (2), and (12) are satisfied. That is, the position Xar of the outer periphery of the antireflection coating 2 is located closer to the optical axis L than the position Xc of the crimped portion 5 of the outermost lens P1. Therefore, even if the object-side end of the housing member 12 is crimped to the outermost lens P1, the stress generated during thermal crimping does not affect the antireflection coating 2. Therefore, the stress generated during thermal crimping does not crack the antireflection coating 2.

[0037] The tip of the crimped portion 4 on the optical axis L side is located in a direction (radial direction) away from the optical axis L relative to the end position Xop of the lens effective surface of the outermost lens P1.

[0038] As described above, in this embodiment, even if the object-side end of the holding member 12 is crimped to the outermost lens P1, it is possible to prevent defects from occurring in the anti-reflection coating 2 provided on the object-side surface of the outermost lens P1.

[0039] [Second Embodiment] Next, a second embodiment will be described. A lens unit 10B according to the second embodiment is substantially the same as the lens unit 10A according to the first embodiment, and therefore the same parts are denoted by the same reference numerals and their description will be omitted, and only the differences will be described.

[0040] Fig. 6 is a cross-sectional view showing an example of a lens unit 10B having an on-vehicle lens according to the second embodiment. Fig. 7 is a diagram showing an example of the lens unit 10B according to the second embodiment, in which the outer periphery of the anti-reflection coating 2 is positioned closer to the optical axis L than the portion that contacts the outermost lens P1 due to the object-side end of the housing member 12 being crimped.

[0041] The outermost lens P1 in the first embodiment is a glass lens, whereas the outermost lens P1 in the second embodiment is a lens made of resin containing an organic material.

[0042] Between the outermost lens P1 and the anti-reflection coating 2, a suppression layer 6 is provided to suppress the thermal stress generated in the outermost lens P1 from being transmitted to the anti-reflection coating 2.

[0043] The outermost lens P1, which is made of a resin containing an organic material, has a high expansion coefficient and undergoes significant volume changes when used in an environment with large temperature changes, such as the inside of a vehicle. Therefore, if the anti-reflection coating 2 is formed directly on the outermost lens P1, the anti-reflection coating 2 will not be able to keep up with the volume changes of the outermost lens P1, and the anti-reflection coating 2 may partially peel off from the outermost lens P1 or cracks may occur in the anti-reflection coating 2. In such cases, the anti-reflection function of the anti-reflection coating 2 will deteriorate if the lens is used for a long period of time as an in-vehicle lens.

[0044] Therefore, in this embodiment, an anti-reflection layer 6 is provided between the outermost lens P 1 and the anti-reflection coating 2 to prevent the thermal stress generated in the outermost lens P 1 from being transmitted to the anti-reflection coating 2 .

[0045] In this embodiment, the antireflection film 2 contains an inorganic material, and the suppression layer 6 contains an organic material and an inorganic material.

[0046] In this way, the outermost lens P1 is a lens made of resin containing an organic material, the anti-reflection coating 2 contains an inorganic material, and the suppression layer 6 between them contains an organic material and an inorganic material, so the suppression layer 6 can prevent thermal stress generated in the outermost lens P1 from being transmitted to the anti-reflection coating 2 more effectively than if the suppression layer 6 were made of only organic material or only inorganic material.

[0047] In this embodiment, the anti-reflection film 2 is further formed by a dry process. The anti-reflection film 2 has a multilayer structure in which high-refractive index layers and low-refractive index layers are alternately stacked, and these high-refractive index layers and low-refractive index layers contain inorganic materials. The anti-reflection film 2 has a multilayer structure in which a total of eight high-refractive index layers and low-refractive index layers are alternately stacked. The layer closest to the object side of the multilayer structure is a low-refractive index layer, and is made of silicon dioxide (SiO ２ The thickness of each layer is 5 nm to 200 nm, and the total thickness of the multilayer structure is 200 nm to 1000 nm, for example, 423 nm.

[0048] The suppression layer 6 of this embodiment is a layer containing an organic material and an inorganic material. Specifically, for example, an acrylic monomer or oligomer, or a urethane monomer or oligomer is used as the organic material, and silicon dioxide or titanium dioxide is used as the inorganic material. The elastic modulus of the suppression layer 6 is preferably 5 GPa or more and 12 GPa or less, and is adjusted by the compounding ratio of the organic material and the inorganic material.

[0049] The suppression layer 6 is generally also called a hard coat layer because it has the function of improving hardness performance. From the viewpoint of imparting the suppression layer 6 with the function of improving hardness performance, it is preferable to use a urethane-based polymer as the organic material and silicon dioxide as the inorganic material.

[0050] The outermost lens P1 is a lens made of a resin containing an organic material, but by providing a hard coat layer as the suppression layer 6, the outermost lens P1, the suppression layer 6 of the hard coat layer, and the entire anti-reflection film 2 can have a scratch hardness comparable to that of a glass lens.

[0051] The surface of the outermost lens P1, which is exposed to the outside, is easily scratched by external impacts. However, the provision of the suppression layer 6, which is a hard coat layer, serves to protect the surface of the outermost lens P1 from scratches.

[0052] In addition, the suppression layer 6, which is a hard coat layer, has a buffering function and reduces the difference in volume expansion between the outermost lens P1 and the anti-reflection coating 2, thereby suppressing peeling and / or cracking of the anti-reflection coating.

[0053] For example, without suppression layer 6 (e.g., hard coat layer), anti-reflection film 2 with a low expansion coefficient is disposed on outermost lens P1, which is a lens made of resin with a high expansion coefficient. When lens unit 10B is exposed to the outside air or the like and stress caused by thermal deformation of outermost lens P1 (a lens made of resin with a high expansion coefficient) is applied to anti-reflection film 2, anti-reflection film 2 is unable to follow the volume change of outermost lens P1, and anti-reflection film 2 cracks.

[0054] However, in this embodiment, an suppression layer 6 (hard coat layer) having an intermediate value between the two expansion coefficients is sandwiched between the outermost lens P1 (a lens made of resin with a large expansion coefficient) and the anti-reflection coating 2. As a result, in this embodiment, stress due to thermal deformation of the outermost lens P1 is absorbed by the suppression layer 6, making it possible to make the anti-reflection coating 2 less likely to crack.

[0055] The suppression layer 6 is not limited to a hard coat layer.

[0056] FIG. 8 is a diagram showing the process of arranging the hard coat layer and the anti-reflection film 2 on the outermost lens P1.

[0057] An inhibition layer 6 of the hard coat layer is provided on the outermost lens P1 (S1). The hard coat layer may be formed by wet coating or dry coating. In the case of wet coating, the hard coat layer is formed on the outermost lens P1 by, for example, spin coating. The film thickness of the inhibition layer 6 of the hard coat layer is 2 to 200 μm.

[0058] The outermost lens P1 with the suppression layer 6 on the upper side is placed on a fixing jig (base) t1, and the outermost lens P1 is fixed with a fixing jig (cover) t2. Evaporated molecules are deposited on the suppression layer 6 on the upper side of the fixed outermost lens P1 to form a thin film (S2). An anti-reflection film (AR layer) 2 is formed. Alternatively, a dry process, such as sputtering, may be used.

[0059] As a result of the above, the suppression layer (hard coat layer) 6 and the anti-reflection film (AR layer) 2 are provided on the outermost lens P1 (S3).

[0060] In the second embodiment, similarly to the first embodiment, an anti-reflection coating 2 is provided so that equations (1), (2), and (12) are satisfied, and even if the object-side end of the holding member 12 is crimped to the outermost lens P1, it is possible to prevent defects from occurring in the anti-reflection coating 2 provided on the object-side surface of the outermost lens P1.

[0061] In the lens unit 10B of the second embodiment, when the elastic modulus of the outermost lens P1, which is a resin lens, is El, the elastic modulus of the anti-reflection film 2 is Ear, and the elastic modulus of the suppression layer 6 is Es, the following formula (3) holds:

[0062] El<Es<Ear (3) The elastic modulus Es of the suppression layer 6 is preferably 5 GPa or more and 12 GPa or less. On the other hand, the elastic modulus E1 of the outermost lens P1 is less than 5 GPa, and the elastic modulus Ear of the antireflection coating 2 is only required to be greater than 12 GPa.

[0063] Incidentally, one of the factors that causes the anti-reflection film 2 to crack as described above is the difference in elastic modulus between the layers.

[0064] If there is no suppression layer 6 (for example, a hard coat layer), the antireflection film 2, which has a high elastic modulus and a thin film thickness, is placed on the outermost lens P1, which is a lens made of resin with a low elastic modulus. For example, if stress is applied to the antireflection film 2 with a finger or the like, the antireflection film 2 will not be able to deform to keep up with the deformation of the outermost lens P1 directly below, and the antireflection film 2 may crack.

[0065] In contrast, in this embodiment, an suppression layer 6 (hard coat layer) having an intermediate value of the two elastic moduli is sandwiched between the outermost lens P1 and the antireflection coating 2. In this state, even if stress is applied to the antireflection coating 2, the suppression layer 6 is less likely to deform than the outermost lens P1, and therefore the suppression layer 6 suppresses deformation of the antireflection coating 2. In other words, even if stress is applied to the antireflection coating 2, the antireflection coating 2 is less likely to crack. In this way, this embodiment can make the antireflection coating 2 less likely to crack.

[0066] [Third Embodiment] Next, a third embodiment will be described. A lens unit 10C according to the third embodiment is substantially similar to the lens unit 10A according to the first embodiment, and therefore the same parts are denoted by the same reference numerals and their description will be omitted, and only the differences will be described.

[0067] 9 is a cross-sectional view showing an example of a lens unit 10C having an on-vehicle lens according to the third embodiment. The position Xar of the outer periphery of the anti-reflection coating 2 is located closer to the optical axis L than the position of the crimped portion 5 of the outermost lens P1.

[0068] Fig. 10A is a diagram showing an example of the state of the outermost lens P1 before the object side end of the housing member 12 of the third embodiment is crimped. Fig. 10B is a diagram showing an example of the state of the outermost lens P1 after the object side end of the housing member 12 of the third embodiment is crimped. Fig. 10C is a diagram showing the state of forming an anti-reflection film on the outermost lens P1 after the object side end of the housing member 12 of the third embodiment is crimped.

[0069] 10A to 10C, in lens unit 10C of this embodiment, after the object-side end of housing member 12 is crimped, anti-reflection coating 2 is provided on the object-side surface of outermost lens P1. Specifically, evaporated molecules are deposited on the object-side surface of outermost lens P1 to form a thin film.

[0070] Therefore, molecules are not deposited in an area on the object-side surface of the outermost lens P1 that is farther away from the optical axis L than the tip P of the crimped portion 4 on the optical axis L side. Therefore, when the position of the outer periphery of the anti-reflection coating 2 in the radial direction with the optical axis L of the outermost lens P1 as the origin is defined as Xar and the position of the crimped portion 5 of the outermost lens P1 is defined as Xc, the anti-reflection coating is provided on the object-side surface of the outermost lens P1 to which the object-side end of the housing member 12 is crimped so that equations (1), (2), and (12) hold true.

[0071] In the third embodiment, similarly to the first embodiment, an anti-reflection coating 2 is provided so that equations (1), (2), and (12) are satisfied, and even if the object-side end of the holding member 12 is crimped to the outermost lens P1, it is possible to prevent defects from occurring in the anti-reflection coating 2 provided on the object-side surface of the outermost lens P1.

[0072] [Fourth embodiment] Next, a fourth embodiment will be described. A lens unit 10D of the fourth embodiment is substantially similar to the lens unit 10A of the first embodiment, and therefore the same parts are denoted by the same reference numerals and their description will be omitted, and only the different parts will be described.

[0073] 11 is a diagram showing an example of the arrangement of the anti-reflection coating 2 and the water-repellent layer 8 on the outermost lens P1 of the fourth embodiment. As shown in Fig. 11, the water-repellent layer 8 is provided on the object-side surface of the anti-reflection coating 2.

[0074] The water-repellent layer 8 also has a protective function. In the section on the problem to be solved by the invention, it is stated that a configuration in which a protective film is not provided on the anti-reflection film is conceivable, but this does not mean that a protective layer is not provided in the technology of the present disclosure either; a protective layer may be provided. The water-repellent layer 8 may be provided on the object-side surface of the anti-reflection film 2 by vapor deposition.

[0075] In the fourth embodiment, similarly to the first embodiment, an anti-reflection coating 2 is provided so that equations (1), (2), and (12) are satisfied, and even if the object-side end of the holding member 12 is crimped to the outermost lens P1, it is possible to prevent defects from occurring in the anti-reflection coating 2 provided on the object-side surface of the outermost lens P1.

[0076] The water-repellent layer 8 may be provided on the object-side surface of the anti-reflection coating 2 formed on the hard coat layer 6 of the second embodiment.

[0077] The water-repellent layer 8 may be provided on the object-side surface of the anti-reflection coating 2 of the third embodiment.

[0078] 10A to 10D: Lens unit P1: Outermost lens L: Optical axis 4: Crimping portion 5: Crimped portion 2: Anti-reflection coating 6: Suppression layer 8: Water-repellent layer 12: Housing member

Claims

1. A lens unit comprising: a plurality of lenses; and a cylindrical housing member that houses the plurality of lenses therein; the housing member has a crimping portion; and an outermost lens of the plurality of lenses, which is located on the opening side of the housing member, is fixed by the crimping portion; the outermost lens has a crimped portion that contacts the crimping portion; and the outermost lens has an anti-reflection coating on at least the object-side surface of the outermost lens; and when the position of the outer periphery of the anti-reflection coating in a radial direction with the optical axis of the outermost lens as the origin is Xar and the position of the crimped portion of the outermost lens is Xc, the following formula is established: Xc>Xar (1).

2. The lens unit according to claim 1, wherein the anti-reflection film covers at least an effective lens surface of the outermost lens, and when an end position of the effective lens surface in a radial direction having an origin at the optical axis of the outermost lens is defined as Xop, the following formula is established: Xar>Xop (2).

3. The lens unit according to claim 1, wherein the outermost lens is a lens made of a resin containing an organic material, and an inhibitor layer is provided between the outermost lens and the anti-reflection film for inhibiting thermal stress generated in the outermost lens from being transmitted to the anti-reflection film.

4. The lens unit according to claim 3, wherein the anti-reflection film contains an inorganic material, and the suppression layer contains an organic material and an inorganic material.

5. The lens unit according to claim 4, wherein the anti-reflection film has a multi-layer structure in which high refractive index layers and low refractive index layers are alternately stacked, and the high refractive index layers and the low refractive index layers contain inorganic materials.

6. The lens unit according to claim 3, wherein the suppression layer is a hard coat layer.

7. The lens unit according to claim 3, wherein the following formula is established: El<Es<Ear (3), where El is the elastic modulus of the resin lens, Ear is the elastic modulus of the anti-reflection film, and Es is the elastic modulus of the suppression layer.

8. The lens unit according to claim 1, further comprising a water-repellent layer provided on the object-side surface of the antireflection film.

9. The lens unit according to claim 1, wherein the housing member contains a thermoplastic resin material.

10. The lens unit described in claim 1, wherein the outer circumferential position Xar of the anti-reflection coating is set based on the thickness of the anti-reflection coating and the distance between the surface of the crimped portion facing the outermost lens and the object-side surface of the outermost lens so that formula (1) holds.

11. A method for manufacturing a lens unit comprising a plurality of lenses and a cylindrical housing member that houses the plurality of lenses therein, comprising: providing an anti-reflection film on at least an object-side surface of an outermost lens of the plurality of lenses that is located on the opening side of the housing member; and crimping the object-side end of the housing member to the outermost lens so as to hold the outermost lens after the anti-reflection film is provided, wherein by crimping the object-side end of the housing member to the outermost lens, the housing member has a crimped portion and the outermost lens has a crimped portion in contact with the crimped portion, and the anti-reflection film is provided so that the following mathematical formula is satisfied: Xc>Xar. (1) A method for manufacturing a lens unit.

12. A lens unit comprising a plurality of lenses and a cylindrical housing member that houses the plurality of lenses therein, the object side end of the housing member being crimped to the outermost lens so as to hold an outermost lens of the plurality of lenses that is located on an opening side of the housing member, wherein by crimping the object side end of the housing member to the outermost lens, the housing member has a crimping portion and the outermost lens has a crimped portion in contact with the crimping portion, and the anti-reflection film is provided on the object side surface of the outermost lens to which the object side end of the housing member is crimped so that the following formula is satisfied: Xc>Xar. (1) A lens unit comprising:

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