Lens unit, camera module and method for manufacturing lens unit

Abstract

Compared with the prior art, the performance of the lens unit is improved. The lens unit has a first lens and a second lens, a portion of the first lens and a portion of the second lens are in contact with each other through an anti-reflection film, and a surface interval between the first lens and the second lens is set to be d. When the film thickness of the anti-reflection film between the portion of the first lens and the portion of the second lens is set as t, d < 100 [mu] m and t < 1500 nm are satisfied.

Description

Technical Field

[0001] This disclosure relates to a lens unit, a camera module, and a method for manufacturing the lens unit. Background Technology

[0002] Patent Document 1 discloses a lens unit in which a highly heat-resistant anti-reflective film is formed on the surface of each of a plurality of resin lenses constituting a lens group. In the above-described lens unit, the thickness of the anti-reflective film has not been considered when the lenses are held in contact with each other.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2019-101070A Summary of the Invention

[0006] The technical problem that the invention aims to solve

[0007] In recent years, there has been a demand for lens units with increasingly higher resolution, so the film thickness, which was never considered before, has now become a factor. This is because the antireflective coating also has a thickness. If the lenses are held in contact without considering their film thickness, the interplanar spacing of the lenses will be greater than the predetermined interplanar spacing, leading to field curvature and other issues that degrade the performance of the lens unit.

[0008] This disclosure is made in view of the above facts, and its purpose is to provide a lens unit, a camera module, and a method for manufacturing the lens unit that can improve the performance of the lens unit compared with the prior art.

[0009] Technical solutions for solving technical problems

[0010] To achieve the above objectives, the lens unit of the first aspect of this disclosure includes a first lens and a second lens, a portion of the first lens and a portion of the second lens being in contact through an anti-reflective film. When the surface spacing between the first lens and the second lens is set to d, and the thickness of the anti-reflective film between the portion of the first lens and the portion of the second lens is set to t, d < 100 μm t < 1500 nm.

[0011] The second aspect of the camera module includes the lens unit of the first aspect.

[0012] The third aspect is a method for manufacturing a lens unit, the lens unit having a first lens and a second lens, the method comprising bringing a portion of the first lens and a portion of the second lens into contact through an anti-reflective film, wherein the thickness of the anti-reflective film between the portion of the first lens and the portion of the second lens is predetermined, such that when the portion of the first lens and the portion of the second lens are in contact through the anti-reflective film, the surface spacing between the first lens and the second lens becomes a predetermined spacing.

[0013] Invention Effects

[0014] Compared with the prior art, the technology disclosed herein can improve the performance of the lens unit. Attached Figure Description

[0015] Figure 1 This is a perspective view of the lens unit according to the first embodiment.

[0016] Figure 2 This is a cross-sectional view of the lens unit.

[0017] Figure 3 This is an exploded 3D view of the lens unit.

[0018] Figure 4 This is an exploded stereoscopic view of lenses L3 and L4 as seen from the object side.

[0019] Figure 5 This is a exploded stereoscopic view of lenses L3 and L4 as seen from the image side.

[0020] Figure 6 This is an exploded stereoscopic view of lenses L5 and L6 as seen from the object side.

[0021] Figure 7 This is an exploded stereoscopic view of lenses L5 and L6 as seen from the image side.

[0022] Figure 8 It is a three-dimensional diagram of the cage, lens L5, and lens L6.

[0023] Figure 9 This is a cross-sectional view of the first lens tube.

[0024] Figure 10 This is a stereoscopic view of the second lens tube as observed from the object side.

[0025] Figure 11 This is a cross-sectional view of the second lens tube.

[0026] Figure 12A This diagram shows the contact between lens L5 and lens L6.

[0027] Figure 12BThis is a diagram showing the surface spacing d between lens L5 and object-side lens L61.

[0028] Figure 13A This diagram shows the contact portion 26 of lens L5 in contact with the contacted portion 37 of lens L6.

[0029] Figure 13B This is a diagram showing the angle θ of the inclined surface of the contacted portion 37 of the object-side lens L61 relative to the optical axis direction.

[0030] Figure 14 This is a diagram showing the structure of the anti-reflective film 302 deposited on the contact portion 26 of lens L5 and the structure of the anti-reflective film 302 deposited on lens L6.

[0031] Figure 15 It is an MTF plot where the horizontal axis shows the defocus distance (nm) and the vertical axis shows the MTF value, and it is an MTF plot when the film thickness t is the optical design value.

[0032] Figure 16 It is an MTF plot where the horizontal axis shows the defocus distance (nm) and the vertical axis shows the MTF value, and it is an MTF plot when the film thickness t is 800nm ​​(0.8μm).

[0033] Figure 17 It is an MTF plot where the horizontal axis shows the defocus distance (nm) and the vertical axis shows the MTF value, and it is an MTF plot when the film thickness t is 1100nm (1.1μm).

[0034] Figure 18 It is an MTF plot where the horizontal axis shows the defocus distance (nm) and the vertical axis shows the MTF value, and it is an MTF plot when the film thickness t is 1600nm (1.6μm).

[0035] Figure 19 This is a schematic diagram of the camera device 350. Detailed Implementation

[0036] Embodiments of the present disclosure will now be described with reference to the accompanying drawings.

[0037] (Optical system)

[0038] Figure 1 This is a perspective view showing the appearance of a lens unit to which the present disclosure technology is applied. Figure 2 This is a cross-sectional view of the lens unit. Figure 3 This is an exploded 3D view of the lens unit. Figure 4 This is an exploded stereoscopic view of lenses L3 and L4 as seen from the object side. Figure 5 This is a exploded stereoscopic view of lenses L3 and L4 as seen from the image side. Figure 6 This is an exploded stereoscopic view of lenses L5 and L6 as seen from the object side. Figure 7 This is an exploded stereoscopic view of lenses L5 and L6 as seen from the image side. Figure 8 It is a three-dimensional diagram of the cage, lens L5, and lens L6. Additionally, in Figure 2 In the diagram, the shapes of each lens are shown in the area between the two double-dotted lines (around the optical axis).

[0039] Figure 1 The lens unit 1 shown is used in camera equipment mounted on automobiles or surveillance cameras. For example... Figure 2 As shown, lens unit 1, from the object side (X1) to the image side (X2), includes lenses L1, L2, L3, L4, L5, and L6 in sequence. Lens L6 is a conjoined lens, which includes an object-side lens L61 and an image-side lens L62 in sequence from the object side to the image side. Lens unit 1 also includes a first lens barrel 3 and a second lens barrel 4, which serve as lens barrel 2. The second lens barrel 4 is located on the inner circumference of the first lens barrel 3. Lens L1 is housed in the first lens barrel 3. Lenses L2 to L6 are housed in the second lens barrel 4. The second lens barrel 4 is located on the inner circumference of the first lens barrel 3.

[0040] like Figure 3 As shown, lens L1 and the first lens barrel 3 constitute the first unit 50. Lenses L2 to L6 and the second lens barrel 4 constitute the second unit 60. In the following description, the direction along the optical axis L of lens L1 is called the optical axis direction X. The optical axis L of lens L1 is the same as the optical axis L of lens unit 1. The object side X1 of the optical axis direction X is the side where lens L1 is located, and the image side X2 is the side where lens L6 is located.

[0041] like Figure 2 As shown, the outer diameter of lens L1 is larger than that of lenses L2 to L6. In this example, lens L1 is made of glass. Lens L1 is a meniscus lens with a convex shape on the object side X1. Lens L1 has an annular end face 11 on the outer periphery of the lens surface on the image side X2, which extends in a direction perpendicular to the optical axis L. A first O-ring 7 is disposed on the image side X2 of the end face 11 of lens L1.

[0042] Lens L2 is made of resin. Lens L2 includes: a lens body portion 13 having a lens surface; and a flange portion 14 surrounding the lens body portion 13. Lens L2 is a meniscus lens with a convex object side X1. On the object side X1 end face of the flange portion 14, an annular protrusion 15 is provided, protruding toward the object side X1. The front end of the annular protrusion 15 is an annular contact portion 15a, which makes surface contact with the end face of lens L1.

[0043] like Figure 2 , Figure 4 and Figure 5As shown, lens L3 is made of resin. Lens L3 includes: a lens body portion 16 having a lens surface; and a flange portion 17 surrounding the lens body portion 16. Lens L3 is a meniscus lens with a convex shape on the image side X2. Figure 5 As shown, an annular fitting portion 18 protruding toward the image side X2 is provided on the end face of the flange portion 17. The fitting portion 18 includes: a fitting portion conical surface 18a, which is inclined toward the inner peripheral side of the image side X2 around the optical axis L; and a fitting portion end face 18b, which extends perpendicularly to the optical axis L from the end of the fitting portion conical surface 18a on the image side X2 toward the inner peripheral side.

[0044] Here, as Figure 2 As shown, an elastic member is provided between lens L2 and lens L3 along the optical axis X. The elastic member is a second O-ring 8. The second O-ring 8 is compressed along the optical axis X between the flange portion 14 of lens L2 and the flange portion 17 of lens L3. In this example, a light-shielding sheet 9 made of resin is provided between lens L2 and lens L3 along the optical axis X. The light-shielding sheet 9 is annular. The second O-ring 8 is located between the light-shielding sheet 9 and lens L3.

[0045] Lens L4 is made of resin. For example... Figure 2 , Figure 4 and Figure 5 As shown, lens L4 includes: a lens body portion 20 having a lens surface; and a flange portion 21 surrounding the lens body portion 20. The lens surface on the object side X1 of the lens body portion 20 of lens L4 is a curved surface protruding towards the object side X1. The lens surface on the image side X2 of the lens body portion 20 has a curved surface portion protruding towards the image side X2 at its center.

[0046] like Figure 4 As shown, the object-side X1 end face of the flange portion 21 is provided with a fitting portion 22, which is fitted with the fitting portion 18 of the lens L3. The fitting portion 22 includes: a fitting portion tapered surface 22a, which is inclined inwardly around the optical axis L and toward the image side X2; and a fitting portion end face 22b, which extends perpendicularly to the optical axis L from the end of the fitting portion tapered surface 22a on the image side X2 toward the inwardly peripheral side. Figure 2 As shown, the conical surface 18a of the fitting portion of lens L3 and the conical surface 22a of the fitted portion of lens L4 are in surface contact. The end face 18b of the fitting portion of lens L3 and the end face 22b of the fitted portion of lens L4 are separated in the optical axis direction X. In this example, the image-side X2 end face of the outer peripheral portion of the fitting portion 18 in the flange portion 17 of lens L3 is in contact with the object-side X1 end face of the outer peripheral portion of the fitted portion 22 in the flange portion 21 of lens L4 in the optical axis direction X. Thus, lens L3 is mounted on lens L4, and lens L3 is positioned in the optical axis direction X.

[0047] Lens L5 is made of glass. For example... Figure 2As shown, the outer diameter of lens L5 is smaller than that of lenses L2, L3, L4, and L6. Lens L5 includes: a lens body 24 having a lens surface; and a flange 25 surrounding the lens body 24. Lens L5 is a biconvex lens. Figure 2 and Figure 7 As shown, the image side X2 of the flange 25 is the contact portion 26, which contacts the lens L6 from the object side X1. The cross-section of the contact portion 26, cut along the optical axis L, is an arc curving outwards towards the image side X2. Figure 7 As shown, the image-side X2 surface of the contact portion 26 is continuous with the outer peripheral end of the image-side X2 lens surface 24a of the lens body portion 24, without any steps.

[0048] like Figure 2 As shown, a retainer 28 made of resin is disposed radially outward of lens L5. Figure 8 As shown, the retainer 28 is annular. The retainer 28 includes: a central portion 29, which is radially adjacent to the lens L5 at a gap 28a; and an outer peripheral portion 30, located on the outer periphery of the central portion 29 and thicker than the central portion 29 in the optical axis direction X. The object-side X1 surface of the central portion 29 slopes from the outer peripheral portion 30 toward the image-side X2. Notches 31 are provided at three circumferential positions on the central portion 29 and the outer peripheral portion 30, cutting out from the object-side X1 and the inner peripheral side. The bottom surface of the notches 31 (the surface facing the object-side X1) is continuous with the end edge of the inner peripheral side of the central portion 29.

[0049] Here, an aperture 33 is disposed between lens L4 and lens L5. Aperture 33 is a ring-shaped sheet sandwiched between lens L4 and holder 28, and supported at a predetermined position in the optical axis direction X.

[0050] Lens L6 is made of resin. That is, both the object-side lens L61 and the image-side lens L62 are made of resin. Figure 2 As shown, the object-side lens L61 includes: a lens body portion 35 having a lens surface; and a flange portion 36 surrounding the lens body portion 35. The lens surface of the object-side lens L61 on the object side X1 is a curved surface that curves toward the image side X2, while the lens surface of the image side X2 is a curved surface that is concave toward the object side X1.

[0051] like Figure 2 As shown, the flange portion 36 of the object-side lens L61 has a contact portion 37 on the object side X1 (see...). Figure 6 The contact portion 26 of the lens L5 is in contact with the contact portion 37. The contacted portion 37 is an inclined surface extending outward toward the object side X1.

[0052] Figure 12A This diagram shows the contact between lens L5 and lens L6. Figure 12BThis is a diagram showing the surface spacing d between lens L5 and object-side lens L61. Figure 13A This diagram shows the contact portion 26 of lens L5 in contact with the contacted portion 37 of object-side lens L61. Figure 13B This is a diagram showing the angle θ of the inclined surface of the contacted portion 37 of the object-side lens L61 relative to the optical axis direction. Figure 14 This diagram shows the structure of the antireflective film 302 deposited on the contact portion 26 of lens L5 and the structure of the antireflective film 304 deposited on lens L6.

[0053] An antireflective film is deposited on the lens surface of lens L5, specifically on the surface of the lens body 24 and the object-facing flange 25, and on the lens surface of the lens body 35 and the object-facing flange 36 of object-side lens L61. Alternatively, an antireflective film may be deposited on the side surface of flange 25 and the side surface of object-side lens L61.

[0054] like Figure 13A and Figure 14 As shown, the contact portion 26 of lens L5 and the contacted portion 37 of object-side lens L61 are in contact through an anti-reflective film 324. Object-side lens L61 is made of resin (or glass). The contact portion 26 of lens L5 is part of the lens surface of lens L5 and is located outside the effective diameter range of the optical system. Figures 13A to 14 The film thickness was exaggerated in the text. Figure 12A and Figure 12B The anti-reflective coating 324 is omitted in the text.

[0055] When the surface spacing between lens L5 and object-side lens L61 is set to d, and the thickness of the antireflective film 324 between the contact portion 26 of lens L5 and the contacted portion 37 of object-side lens L61 is set to t, the lens unit 1 satisfies the following conditions (1) and (2).

[0056] d < 100 μm (1)

[0057] t < 1500 nm (2)

[0058] The contact portion 26 of lens L5 is an example of a "part of a first lens" in this disclosure. The contacted portion 37 of lens L6 is an example of a "part of a second lens" in this disclosure.

[0059] Here, as Figure 12B As shown, the surface spacing d between lens L5 and object-side lens L61 is the shortest among the surface spacings between lens L5 and object-side lens L61, and it is also the spacing between lens L5 and object-side lens L61 on the optical axis L.

[0060] The preferred interfacial spacing d is 20 μm < d < 70 μm.

[0061] An antireflective film 324 is deposited on at least one of the contact portion 26 of the lens L5 and the contacted portion 37 of the object-side lens L61. In this embodiment, as... Figure 14 As shown, the antireflective film 324 is deposited on both the contact portion 26 of the lens L5 and the contacted portion 37 of the object-side lens L61. When the thickness of the antireflective film 302 deposited on the contact portion 26 of the lens L5 is set to t1, and the thickness of the antireflective film 304 deposited on the contacted portion 37 of the object-side lens L61 is set to t2, the lens unit preferably satisfies the following condition (3).

[0062] t1+t2<1100nm (3)

[0063] In this embodiment, such as Figure 14 As shown, the antireflective film 324, specifically the antireflective film 302 deposited on the contact portion 26 of the lens L5, and the antireflective film 304 deposited on the contacted portion 37 of the object-side lens L61, each comprises multiple layers. The antireflective film 302 comprises layers 302N1 to 302N7. The antireflective film 304 comprises layers 304N1 to 304N7. Therefore, the antireflective films 302 and 304 each have a multilayer structure. Specifically, low-refractive-index layers and high-refractive-index layers are alternately stacked along the thickness direction (the direction of the optical axis L).

[0064] The low refractive index layer preferably comprises one or more of, for example, SiO2, Al2O3 and MgF2.

[0065] The high refractive index layer preferably comprises any one or more of, for example, Si3N4, ZrO2, TiO2, Ti3O5, Ta2O5, In2O3, CeO2 and Nb2O5.

[0066] The thickness of a low-refractive-index layer is, for example, 5.0 nm or more and 200.0 nm or less. The thickness of a high-refractive-index layer is, for example, 5.0 nm or more and 200.0 nm or less.

[0067] When antireflective film 302 and antireflective film 304 have multilayer structures, the thickness t of antireflective film 304 preferably satisfies the following condition (4).

[0068] 100nm<t(=t1+t2)<1100nm (4)

[0069] As described above, lens L5 includes: a lens body portion 24 having a lens surface; and a flange portion 25 surrounding the lens body portion 24 and having a flange surface provided at the outer periphery of the lens surface. The contact portion 26 of lens L5 is a part of the flange surface of lens L5. The cross-section of the contact portion 26 of lens L5, including the optical axis L, is an arc protruding toward the object-side lens L61. As described above, object-side lens L61 includes: a lens body portion 35 having a lens surface; and a flange portion 36 surrounding the lens body portion 35 and having a flange surface provided at the outer periphery of the lens surface. Figure 13B As shown, the contacted portion 37 of the object-side lens L61 is part of the flange surface of the object-side lens L61, and is an inclined surface that is inclined at an angle of more than 45° relative to the optical axis direction X.

[0070] The vapor deposition direction of the anti-reflective film is the optical axis direction X. Therefore, if the tilt angle θ of the inclined surface of the contacted part 37 relative to the optical axis direction X is less than 45°, the direction of the inclined surface of the contacted part 37 is closer to the vapor deposition direction of the anti-reflective film (optical axis direction X). The anti-reflective film cannot cover the inclined surface of the contacted part 37, the film thickness becomes very thin, and the anti-reflective film may lose its function.

[0071] The flange portion 36 of the object-side lens L61 has an annular end face 38 perpendicular to the optical axis L on the image side X2.

[0072] The image-side lens L62 includes: a lens body portion 40 having a lens surface; and a flange portion 41 surrounding the lens body portion 40. The object-side lens surface X1 of the image-side lens L62 is a curved surface protruding towards the object side X1, and the image-side lens surface X2 is a curved surface protruding towards the image side X2. The image-side lens L62 is fixed to the object-side lens L61. The outer diameter of the image-side lens L62 is smaller than the outer diameter of the object-side lens L61. Therefore, as... Figure 7 As shown, when viewed from the image side X2, a portion of the flange 36 of the object-side lens L61 extends outward from the image-side lens L62 to the outer periphery.

[0073] Here, as Figure 2 As shown, lens L5 is stacked on lens L6. Furthermore, lens L4 is stacked on lens L6 via a retainer 28. Lens L4, retainer 28, lens L5, and lens L6 constitute a stack 44. Lens L3 is stacked on lens L4. That is, lens L3 is stacked on stack 44. Additionally, a plate-shaped cover 10 is provided on the image side X2 of lens L6. (Lens tube)

[0074] like Figure 2 and Figure 3As shown, the lens unit 1 includes a first lens barrel 3 and a second lens barrel 4, which serve as lens barrels 2. The second lens barrel 4 is located on the inner circumferential side of the first lens barrel 3. Both the first lens barrel 3 and the second lens barrel 4 are made of resin. Furthermore, the first lens barrel 3 and the second lens barrel 4 are resin injection molded products formed by injecting resin into a mold. Lens L1 is housed in the first lens barrel 3. Lenses L2 to L6 and a retainer 28 are housed in the second lens barrel 4. The second lens barrel 4 is located on the inner circumferential side of the first lens barrel 3. (First lens barrel and lens L1)

[0075] Figure 9 This is a cross-sectional view of the first lens barrel 3. The first lens barrel 3 is cylindrical and located on the outer periphery of lenses L2, L3, L4, retainer 28, L5, L6, and the second lens barrel 4. Figure 3 and Figure 9 As shown, the first lens barrel 3 has an object-side step portion 101 at the object-side X1 end of its inner circumferential surface and an image-side step portion 102 at the image-side X2 end. Furthermore, the first lens barrel 3 includes an intermediate step portion 103 between the object-side step portion 101 and the image-side step portion 102 in the optical axis direction X on its inner circumferential surface.

[0076] The object-side step portion 101 includes: a support surface 105 facing the object side X1; an annular wall surface 106 extending from the inner peripheral end of the support surface 105 toward the image side X2 and toward the radially inward side; and a peripheral wall surface 107 extending from the outer peripheral end of the support surface 105 toward the object side X1. In the first lens barrel 3, the object side X1 of the object-side step portion 101 is a receiving portion 108 that receives the outer peripheral portion of the lens L1. Furthermore, the second lens barrel 4 is disposed on the inner peripheral side of the annular wall surface 106.

[0077] The storage section 108 includes a peripheral wall surface 107, a support surface 105, and a riveting section 109. For example... Figure 2 As shown, the peripheral wall surface 107 faces the lens L1 from the radially outer side. The support surface 105 faces the end face 11 of the lens L1 from the image side X2. The riveting part 109 abuts against the lens L1 from the object side X1 at the position where it overlaps with the support surface 105 when viewed from the optical axis direction X along the optical axis L of the lens L1.

[0078] The riveting portion 109 is a plastically deformable portion provided by heat riveting or the like by bending the object-side X1 end of the first lens barrel 3 inward to the inner periphery. Here, the outer periphery of the lens L1 is disposed between the support surface 105 and the riveting portion 109. The first O-ring 7 is disposed between the image-side X2 end face of the lens L1 and the support surface 105, and is compressed along the optical axis direction X.

[0079] like Figure 3As shown, the annular wall surface 106 is provided with object-side protrusions 110, which protrude radially inward at multiple locations in the circumferential direction. In this example, the object-side protrusions 110 are arranged at three locations in the circumferential direction at equal angular intervals. The object-side protrusions 110 are object-side positioning parts used for radially positioning the second lens barrel 4.

[0080] like Figure 3 and Figure 10 As shown, the image-side stepped portion 102 includes: an annular image-side end face 112 facing the object side X1; and an annular image-side inner wall surface 113 extending from the inner circumferential end of the image-side end face 112 toward the image side X2 and reaching the image-side X2 end of the first lens barrel 3. The image-side end face 112 is provided with a plurality of ribs 114, which protrude toward the object side X1 and extend in an arc shape along the circumference. In this example, the ribs 114 are provided at three locations at equal angular intervals in the circumferential direction. The ribs 114 are image-side positioning portions for positioning the second lens barrel 4 in the optical axis direction X.

[0081] The intermediate step portion 103 includes: an annular step portion end face 116 facing the object side X1; and an annular step portion wall surface 117 extending from the inner circumferential end of the step portion end face 116 toward the image side X2. In this example, the intermediate step portion 103 has notches 118 at multiple locations in the circumferential direction. The notches 118 extend along the optical axis X and divide the step portion end face 116 and the step portion wall surface 117 circumferentially. In this example, the notches 118 are provided at three locations at equal angular intervals in the circumferential direction. Therefore, the intermediate step portion 103 is divided into three parts in the circumferential direction by the notches 118. The bottom surface (the surface facing the inner circumferential side) of the notches 118 is a conical surface, and the inner diameter decreases toward the image side X2. Figure 2 As shown, the bottom surface of the notch 118 is continuous with the inner peripheral surface of the first lens barrel 3, which extends from the outer peripheral end of the image-side end face 112 of the image-side step portion 102 toward the object side X1.

[0082] Here, as Figure 3 As shown, the notch 118 is positioned at the same angle as the rib 114 of the image-side step portion 102. Furthermore, the notch 118 is positioned at the same angle as the object-side protrusion 110 of the object-side step portion 101. Additionally, when connecting the first lens barrel 3 and the second lens barrel 4 disposed on the inner periphery of the first lens barrel 3, adhesive is applied to the end face 116 of each step portion of the three-part intermediate step portion 103. Thus, an adhesive layer 51 for lens barrel connection is provided on the step portion end face 116 and the step portion wall surface 117. (Second lens barrel and lenses L2 to L6)

[0083] Figure 10 This is a stereoscopic view of the second lens tube 4 as observed from the object side. Figure 11 This is a cross-sectional view of the second lens tube 4. Figure 11The area enclosed by the dashed line is a magnified view of the periphery of the fitting protrusion 210. The second lens tube 4 houses lenses L2, L3, L4, L5, the retainer 28, and lens L6 on its inner periphery.

[0084] like Figure 10 and Figure 11 As shown, the second lens barrel 4 has an object-side stepped portion 201 at the object-side X1 end of its inner circumferential surface. Furthermore, the second lens barrel 4 has an image-side stepped portion 202 at the image-side X2 end. Additionally, the second lens barrel 4 includes a positioning stepped portion 203 between the object-side stepped portion 201 and the image-side stepped portion 202, which is positioned closer to the image-side stepped portion 202 than to the object-side stepped portion 201. Furthermore, the second lens barrel 4 includes a cover retaining portion 204 for the retaining cap 10 at the image-side X2 end.

[0085] like Figure 11 As shown, the object-side step portion 201 includes: a seat surface 205 facing the object side X1; an annular wall surface 206 extending from the inner peripheral end of the seat surface 205 toward the image side X2; and a peripheral wall surface 207 extending from the outer peripheral end of the seat surface 205 toward the object side X1. The annular wall surface 206 is a conical surface whose inner diameter increases toward the object side X1. In the second lens barrel 4, the object side X1 of the object-side step portion 201 is a receiving portion 208 for receiving the outer peripheral portion of the lens L2.

[0086] The storage section 208 includes a peripheral wall surface 207, a seat surface 205, and a riveting section 209. For example... Figure 2 As shown, the peripheral wall surface 207 is radially outward opposite to the lens L2. The seat surface 205 is opposite to the image-side X2 end face of the flange portion 14 of the lens L2 from the image side X2. The riveting portion 109, when viewed from the optical axis direction X, overlaps with the seat surface 205 and abuts against the lens L2 from the object side X1.

[0087] like Figure 10 As shown, the peripheral wall surface 207 is a tapered surface that slopes outward from the seat surface 205 toward the object side X1 toward the outer peripheral side. Multiple portions of the peripheral wall surface 207, separated in the circumferential direction, include fitting protrusions 210A, which press against the lens L2. In this example, the fitting protrusions 210A are arranged at equal angular intervals in the circumferential direction at six locations. The fitting protrusions 210A have a pressing surface 210a parallel to the optical axis L at their inner peripheral end. Furthermore, the fitting protrusions 210A have a curved surface 210b that curves outward from the pressing surface 210a toward the object side X1 toward the outer peripheral side. The pressing surfaces 210a of the multiple fitting protrusions 210A press against the lens L2 received by the receiving portion 208 from the radially outer side, thereby positioning the lens L2 radially.

[0088] like Figure 11As shown, the image-side stepped portion 202 includes: an annular image-side end face 212 facing the object side X1; and an image-side inner wall surface 213 extending from the inner peripheral end of the image-side end face 212 toward the image side X2. The image-side inner wall surface 213 is a conical surface inclined toward the outer peripheral side toward the image side X2. Figure 2 As shown, the image-side end face 212 is spaced apart from the image-side lens L62 of the lens L6 in the optical axis direction X. The cover retaining part 204 is provided on the outer peripheral side of the image-side inner wall surface 213.

[0089] like Figure 10 and Figure 11 As shown, the positioning step portion 203 includes: an annular positioning surface 215 facing the object side X1; and a positioning step portion peripheral wall surface 216 extending from the inner peripheral end of the positioning surface 215 toward the image side X2. The positioning surface 215 is provided with a plurality of positioning ribs 217, which protrude toward the object side X1 and extend in an arc shape along the circumference. In this example, the positioning ribs 217 are provided at three locations at equal angular intervals in the circumferential direction. The lower end of the positioning step portion peripheral wall surface 216 reaches the image side end face 212 of the image side end face 212. The positioning step portion peripheral wall surface 216 is radially opposed to the image side lens L62 of the lens L6 by a gap.

[0090] like Figure 2 As shown, the positioning rib 217 is a positioning part that abuts against the flange 36 of the object-side lens L61 of lens L6 from the image side X2, and positions lens L6 in the optical axis direction X. Here, the flange 36 of the object-side lens L61 of lens L6 abuts against the positioning part, so that the laminate 44 composed of lens L4, holder 28, lens L5, and lens L6 and lens L3 are positioned in the optical axis direction X.

[0091] More specifically, the retainer 28 is supported by the lens L6 from the image side X2, thereby being positioned at a predetermined position in the optical axis X. The lens L4 is supported by the retainer 28 from the image side X2, thereby being positioned at a predetermined position in the optical axis X. The lens L5 is positioned in the optical axis X and radially by contacting the lens L6. The lens L3 is positioned in the optical axis X and radially by engaging with the lens L4. Here, when the lens L5 is positioned in the optical axis X and radially, the lens L5 and the retainer 28 are not in contact. When the lenses L3 and L4 are positioned in the optical axis X and radially, the lens L3 and the second lens barrel 4 are not in contact. The lenses L3, L4, retainer 28, and lens L5 are located in the optical axis X between the object-side step 201 and the positioning step 203.

[0092] like Figure 10 and Figure 11As shown, on the inner circumferential surface of the second lens barrel 4, the inner circumferential surface 4a located radially outward of the object-side lens L61 of the lens L6 is a conical surface inclined towards the object-side X1 towards the outer circumferential side. The inner circumferential surface 4a has multiple mating protrusions 210B at circumferentially separated locations, which press against the lens L6. The mating protrusions 210B are arranged at equal angular intervals in six locations circumferentially. The mating protrusions 210B have a pressing surface 210a parallel to the optical axis L at their inner circumferential ends. Furthermore, the mating protrusions 210B have a curved surface 210b that curves from the pressing surface 210a towards the object-side X1 towards the outer circumferential side. The pressing surfaces 210a of the multiple mating protrusions 210B press against the lens L6 housed in the second lens barrel 4 from the radially outward side, thereby positioning the lens L6 radially.

[0093] Furthermore, on the inner circumferential surface of the second lens barrel 4, the inner circumferential surface portion 4b located radially outward of the retainer 28 is a conical surface inclined towards the object side X1 and towards the outer circumferential side. The inner circumferential surface portion 4b has multiple circumferentially separated portions with fitting protrusions 210C, which press against the lens L6. The fitting protrusions 210C are arranged at equal angular intervals in six portions circumferentially. The fitting protrusions 210C have a pressing surface 210a parallel to the optical axis L at their inner circumferential ends. Furthermore, the fitting protrusions 210C have a curved surface 210b that curves from the pressing surface 210a towards the object side X1 and towards the outer circumferential side. The pressing surfaces 210a of the multiple fitting protrusions 210C press against the retainer 28 housed in the second lens barrel 4 from the radially outward side, thereby positioning the retainer 28 radially.

[0094] Furthermore, on the inner circumferential surface of the second lens barrel 4, the inner circumferential surface portion 4c located radially outward of the lens L4 is a conical surface inclined towards the object side X1 and toward the outer circumferential side. The inner circumferential surface portion 4c has multiple interlocking protrusions 210D at circumferentially separated locations, which press against the lens L4. The interlocking protrusions 210D are arranged at equal angular intervals in six locations circumferentially. The interlocking protrusions 210D have a pressing surface 210a parallel to the optical axis L at their inner circumferential end. Furthermore, the interlocking protrusions 210D have a curved surface 210b that curves from the pressing surface 210a toward the object side X1 and toward the outer circumferential side. The pressing surfaces 210a of the multiple interlocking protrusions 210D press against the lens L4 housed in the second lens barrel 4 from the radially outward side, thereby positioning the lens L4 radially.

[0095] Furthermore, on the inner circumferential surface of the second lens barrel 4, the inner circumferential surface portion 4d located radially outer of the lens L3 is a conical surface inclined towards the object side X1 and towards the outer circumferential side. The inner circumferential surface portion 4d located radially outer of the lens L3 is continuous with the image side X2 of the annular wall surface 206 of the object side step portion 201, without any steps. The inner circumferential surface portion 4d has guide protrusions 220 at multiple locations separated in the circumferential direction, which guide the lens L3 along the optical axis X. The guide protrusions 220 are arranged at equal angular intervals in six locations in the circumferential direction. The guide protrusions 220 have a guide surface 220a parallel to the optical axis L at their inner circumferential end. Furthermore, the guide protrusions 220 have a curved surface 220b that curves from the pressing surface 210a towards the object side X1 and towards the outer circumferential side. When the lens L3 is fitted with the lens L4, the multiple guide protrusions 220 are located radially outer of the lens L3 but do not contact the lens L3. The guide surfaces 220a of each guide protrusion 220 and the lens L3 are radially separated by a tiny gap.

[0096] Here, the second O-ring 8 is disposed radially inside the annular wall 206 of the object-side stepped portion 201 on the object-side X1 of the plurality of guide protrusions 220. For example... Figure 2 As shown, the second O-ring 8 is located between the lens L2 and the lens L3 stored in the storage section 208, and is compressed in the optical axis direction X.

[0097] like Figure 11 As shown, the first tilt angle θ1 of the conical inner circumferential surface portion 4a located radially outer of lens L6, which is tilted relative to the optical axis L, is different from the second tilt angle θ2 of the conical inner circumferential surface portion 4c located radially outer of lens L4, which is tilted relative to the optical axis L. That is, the tilt angle of the inner circumferential surface portions 4a to 4d located radially outer of each lens and holder 28 can be appropriately set according to the outer diameter of each lens or holder 28. Furthermore, on the inner circumferential surface of the second lens barrel 4, the inner circumferential surface portion 4a located between the object-side step portion 201 and the positioning step portion 203 is tilted overall towards the object side X1 towards the outer circumferential side.

[0098] Secondly, the second lens barrel 4 has an annular outer peripheral side positioning surface 223 at the object-side X1 end of its outer peripheral surface. The outer peripheral side positioning surface 223 is located radially outward of the receiving portion 208. The outer peripheral side positioning surface 223 faces radially outward. Furthermore, the second lens barrel 4 has an outer peripheral image-side step portion 224 at the image-side X2 portion of its outer peripheral surface. The outer peripheral image-side step portion 224 includes: an annular surface 225 facing the image-side X2; and an outer peripheral surface portion 226 extending from the outer peripheral end of the annular surface 225 toward the object-side X1. Furthermore, the second lens barrel 4 has an outer peripheral intermediate step portion 227 between the object-side X1 end of its outer peripheral surface (outer peripheral side positioning surface 223) and the outer peripheral image-side step portion 224. The outer peripheral intermediate step portion 227 has: an annular surface 228 facing the image-side X2; and an outer peripheral surface portion 229 extending from the inner peripheral end of the annular surface 228 toward the image-side X2.

[0099] (Manufacturing method of lens unit)

[0100] When manufacturing lens unit 1, the second unit assembly operation, in which lenses L2 to L6 are housed in the second lens barrel 4, is performed first. Next, the lens barrel fixing operation is performed to hold and fix the second lens barrel 4 to the first lens barrel 3. Subsequently, the first unit assembly operation, in which lens L1 is housed in the first lens barrel 3, is performed.

[0101] In the second unit assembly operation, firstly, lens L5 is stacked on top of lens L6 outside the second lens barrel 4. In this case, the contact portion 26 of lens L5 and the contacted portion 37 of lens L6 are in contact through the anti-reflective film 324.

[0102] Here, the thickness t of the antireflective film 324 between the contact portion 26 of lens L5 and the contacted portion 37 of object-side lens L61 is predetermined, such that when the contact portion 26 of lens L5 and the contacted portion 37 of object-side lens L61 come into contact through the antireflective film 324, the surface spacing d between lens L5 and object-side lens L61 becomes a predetermined spacing. Specifically, the surface spacing d is d < 100 μm, and the film thickness t is t < 1500 nm.

[0103] More specifically, in this embodiment, the antireflective film 324 is pre-deposited on both the lens L5 and the object-side lens L61. Specifically, the antireflective film is deposited on the lens surface of the lens body portion 24 of the lens L5 and the surface of the flange portion 25 facing the object side, and on the lens surface of the lens body portion 35 of the object-side lens L61 and the surface of the flange portion 36 facing the object side. When the thickness of the antireflective film 302 deposited on the contact portion 26 of the lens L5 is set to t1, and the thickness of the antireflective film 304 deposited on the contacted portion 37 of the object-side lens L61 is set to t2, the antireflective film is pre-deposited on both the lens L5 and the object-side lens L61 such that t1 + t2 < 1100 nm. The lens L5, with the antireflective film pre-deposited, and the object-side lens L61 are brought into contact, such that the contact portion 26 of the lens L5 and the contacted portion 37 of the lens L6 are in contact through the antireflective film 324.

[0104] Subsequently, lens L6 is vibrated until the annular contact line between contact portion 26 and contacted portion 37 lies on an imaginary vertical plane S that is coaxial with and perpendicular to the optical axis L. Here, when the annular contact line between contact portion 26 and contacted portion 37 lies on the imaginary vertical plane S that is coaxial with and perpendicular to the optical axis L, lenses L5 and L6 are aligned. That is, lenses L5 and L6 are positioned relative to each other in the optical axis direction X and radially.

[0105] After alignment, adhesive is applied between lenses L1 and L2 on the outer periphery of the contact line. The adhesive is then allowed to cure. Thus, lenses L6 and L5 are held together by the adhesive layer 52 formed between them.

[0106] Next, the mutually fixed lenses L5 and L6 are stored in the second lens tube 4 from the object side X1. At this time, as... Figure 10 As shown, lens L6 is pressed into the inner circumferential surface of the second lens barrel 4, onto the inner circumferential side of a plurality of fitting protrusions 210B located at the position closest to the image side X2. Thus, the pressing surface 210a of each fitting protrusion 210B presses lens L6 (object-side lens L61) radially outward, positioning lens L6 radially. Furthermore, the flange portion 36 of the object-side lens L61 of lens L6 abuts against the positioning rib 217 of the positioning step portion 203 of the second lens barrel 4. Thus, lens L6 is positioned in the optical axis direction X. When lens L6 is positioned in both the optical axis direction X and radially, lens L5, fixed to lens L6, is also positioned in both the optical axis direction X and radially.

[0107] Next, the retainer 28 is housed in the second lens barrel 4 from the object side X1. At this time, the retainer 28 is pressed into the inner circumferential side of a plurality of fitting protrusions 210C arranged second from the image side X2 on the inner circumferential surface of the second lens barrel 4. As a result, the pressing surfaces 210a of each fitting protrusion 210C press the retainer 28 from the radially outer side, thereby positioning the retainer 28 radially. Furthermore, by bringing the retainer 28 abutting against the lens L6 from the object side X1, the retainer 28 is supported by the lens L6 from the image side X2 and positioned in the optical axis direction X. Here, a gap 28a is formed between the inner circumferential surface of the retainer 28 and the lens L5. Therefore, adhesive is dripped into these gaps 28a, through the adhesive layer 53 (see Figure 8 The retainer 28 and lens L5 are then secured. In this example, adhesive is applied to the notch 31 provided on the outer peripheral portion 30 of the retainer 28. As a result, the adhesive flows along the center portion 29 and reaches the gap 28a between the retainer 28, the inner peripheral surface, and the lens L5.

[0108] Next, lens L4 is housed from the object side X1 into the second lens barrel 4. At this time, lens L4 is pressed into the inner circumferential side of a plurality of fitting protrusions 210D, which are arranged third from the image side X2, on the inner circumferential surface of the second lens barrel 4. Thus, the pressing surface 210a of each fitting protrusion 210D presses lens L4 from the radially outer side, and lens L4 is positioned radially. Furthermore, by bringing lens L4 abutting against the holder 28 from the object side X1, lens L4 is supported by the holder 28 from the image side X2 and positioned in the optical axis direction X. Here, a laminate 44 is formed inside the second lens barrel 4, which consists of lens L4, holder 28, lens L5, and lens L6.

[0109] Next, lens L3 is housed in the second lens barrel 4 from the object side X1. At this time, lens L3 is inserted into the inner circumference of the plurality of guide protrusions 220. Thus, lens L3 is guided in a predetermined posture along the optical axis X, and the fitting portion 18 of lens L3 is inserted into the fitting portion 22 of lens L4. Furthermore, lens L3, guided by the guide protrusions 220, is pushed from the object side X1 toward lens L4. This causes the fitting portion 18 of lens L3 to engage with the fitting portion 22 of lens L4. With the fitting portion 18 of lens L3 and the fitting portion 22 of lens L4 engaged, the tapered surface 18a of the fitting portion 18 and the tapered surface 22a of the fitting portion 22 form surface contact. Thus, lens L3 is positioned radially relative to lens L4. Furthermore, with the fitting portion 18 of lens L3 and the fitted portion 22 of lens L4 engaged, the outer peripheral portion of the fitting portion 18 on the flange portion 17 of lens L3 contacts the outer peripheral portion of the fitted portion 22 on the flange portion 21 of lens L4 in the optical axis direction X. Thus, lens L3 is positioned in the optical axis direction X.

[0110] Next, the second O-ring 8 is placed on the flange 17 of the lens L3 from the object side X1. Then, the light-shielding plate 9 is supported on the support surface 105. Furthermore, the lens L2 is supported on the support surface 105 via the light-shielding plate 9. At this time, the lens L2 is pressed into the inner circumferential side of the fitting protrusion 210A closest to the object side X1 on the inner circumferential surface of the second lens barrel 4. Thus, the pressing surfaces 210a of each fitting protrusion 210A press the lens L2 from the radially outer side, positioning the lens L2 radially. Furthermore, by abutting the lens L2 against the light-shielding plate 9 from the object side X1, the lens L2 is positioned in the optical axis direction X.

[0111] Subsequently, a riveting portion 109, bent inwards, is formed at the object-side X1 end of the second lens barrel 4, so that the riveting portion 109 abuts against the outer peripheral portion of the lens L2 from the object-side X1. In this example, the crimping portion 109 is formed by heat pressing. Thus, the second unit assembly operation is completed. In the state where the second unit assembly operation is completed, the second O-ring 8 is compressed along the optical axis X between the lens L2 and the lens L3.

[0112] Next, the lens barrel fixing action is performed to hold the second unit 60 onto the first unit 50. During the lens barrel fixing action, as follows... Figure 3 and Figure 9 As shown, adhesive is applied to the end faces 116 of the three intermediate stepped portions 103 provided on the inner circumferential surface of the first lens barrel 3. Then, the second unit 60 is inserted into the inner circumferential side of the first lens barrel 3 from the object side X1. Figure 11 and Figure 9 As shown, the annular surface 225 of the image-side step portion 224 on the image-side portion of the outer peripheral surface of the second lens barrel 4 abuts against the rib 114 (image-side positioning portion) of the image-side step portion 102 on the inner peripheral surface of the first lens barrel 3. Furthermore, the annular outer peripheral side positioning surface 223 at the object-side X1 end of the second lens barrel 4 abuts against the object-side protrusion 110 on the annular wall surface 106 of the object-side step portion 101 of the first lens barrel 3.

[0113] Here, apart from the contact portions between the image-side stepped portion 102 of the second lens barrel 4 and the image-side stepped portion 102 of the first lens barrel 3, and the contact portions between the annular positioning surface 215 of the second lens barrel 4 and the object-side stepped portion 101 of the first lens barrel 3, the inner circumferential surface of the first lens barrel 3 and the outer circumferential surface of the second lens barrel 4 are spaced apart and face each other. Therefore, the second lens barrel 4 is positioned relative to the first lens barrel 3 in the optical axis direction X and radial direction by two contact portions.

[0114] Furthermore, when the second unit 60 is inserted into the inner circumference of the first lens barrel 3, the intermediate step portion 103 of the inner circumference surface of the first lens barrel 3 and the intermediate step portion 227 of the outer circumference surface of the second lens barrel 4 face each other with a gap. That is, the step end face 116 of the intermediate step portion 103 of the first lens barrel 3 and the annular surface 228 of the intermediate step portion 227 of the outer circumference surface of the second lens barrel 4 face each other with a gap in the optical axis direction X. Furthermore, the step wall surface 117 of the intermediate step portion 103 of the first lens barrel 3 and the outer circumference portion 229 of the intermediate step portion 227 of the outer circumference surface of the second lens barrel 4 face each other with a gap in the radial direction. Here, when the second unit 60 is inserted into the inner circumference of the first lens barrel 3, the adhesive applied to the step end face 116 of the intermediate step portion 103 of the first lens barrel 3 will spread to the step wall surface 117. Therefore, as Figure 2 As shown, an adhesive layer 51 for connecting the lens barrels is provided between the stepped end face 116 of the intermediate stepped portion 103 of the first lens barrel 3 and the annular surface 228 of the intermediate stepped portion 227 of the outer peripheral surface of the second lens barrel 4. Furthermore, an adhesive layer 51 for connecting the lens barrels is provided between the stepped wall surface 117 of the intermediate stepped portion 103 of the first lens barrel 3 and the outer peripheral surface portion 229 of the intermediate stepped portion 227 of the outer peripheral surface of the second lens barrel 4. The intermediate stepped portion 103 of the first lens barrel 3 and the intermediate stepped portion 227 of the outer peripheral surface of the second lens barrel 4 are adhesive fixing parts, which connect the first lens barrel 3 and the second lens barrel 4 through the adhesive layer 51 for connecting the lens barrels.

[0115] Next, during the first unit assembly operation, the first O-ring 7 is placed on the support surface 105 of the first lens barrel 3. Then, the lens L1 is supported on the support surface 105 by the first O-ring 7. Subsequently, a riveting portion 109, bent inwards, is formed at the object-side X1 end of the first lens barrel 3. This causes the riveting portion 109 to abut against the outer peripheral portion of the lens L1 from the object-side X1. In this example, the crimping portion 109 is formed by heat pressing. When the riveting portion 109 is formed, the first O-ring 7 is compressed along the optical axis X between the image-side X2 end face of the lens L1 and the support surface 105 of the first lens barrel 3.

[0116] Here, when lens L1 is held in the first lens barrel 3, the annular protrusion 15 of the flange portion 14 of lens L2 held in the second lens barrel 4 forms a surface contact with the end face 11 of the image side X2 of lens L1.

[0117] In addition, such as Figure 2As shown, an air passage 70 is formed between the first lens barrel 3 and the second lens barrel 4. This air passage 70 extends from the image-side X2 end 3a of the first lens barrel 3 and the image-side X2 end 4e of the second lens barrel 4, passing through the gap between adjacent ribs 114 in the circumferential direction in the image-side stepped portion 102 of the first lens barrel 3, the notch 118 provided in the intermediate stepped portion 103 of the first lens barrel 3, and the gap between adjacent object-side protrusions 110 in the circumferential direction in the annular wall surface 106 of the object-side stepped portion 101 of the first lens barrel 3. The air passage 70 communicates with the space between the lens L1 and the support surface 105 on the inner circumferential side of the first O-ring 7.

[0118] (Effect)

[0119] In existing lens units, the lenses are held abutting against each other without considering the thickness of the antireflective coating. As a result, the interplanar spacing of the lenses is greater than the predetermined interplanar spacing, which increases the field curvature effect and degrades the performance of the lens unit.

[0120] Furthermore, as the resolution of lens units increases, there is a tendency for sensor sizes to grow. Therefore, there is a tendency to increase lens diameter and the number of lenses in lens units. However, the dimensions of the lens unit itself must remain constant. This leads to a tendency to minimize the inter-lens spacing. Therefore, it is necessary to consider film thickness, which was not previously taken into account. This is because the anti-reflective coating also has thickness; if this thickness is not considered during lens unit manufacturing, the inter-lens spacing will be greater than the predetermined inter-lens spacing, resulting in field curvature and deterioration of the lens unit's performance.

[0121] Therefore, in this embodiment, an antireflective film 324 is deposited on the lens L5 and the object-side lens L61, such that the antireflective film 324 between the contact portion 26 of the lens L5 and the contacted portion 37 of the object-side lens L61 has a thickness t, such that when the contact portion 26 and the contacted portion 37 are in contact through the antireflective film 324, the surface spacing d between the lens L5 and the object-side lens L61 becomes a predetermined spacing. Specifically, the surface spacing d is d < 100 μm, and the film thickness t is t < 1100 nm. Furthermore, in this embodiment, the contact portion 26 of the lens L5 and the contacted portion 37 of the object-side lens L61 are in contact through the antireflective film 324.

[0122] The reason for setting the interfacial spacing d to less than 100 μm is that if the interfacial spacing d is greater than 100 μm, the impact will be smaller when the film thickness t is about 1500 nm.

[0123] The preferred film thickness t is 100 nm < t < 1100 nm.

[0124] The preferred interfacial spacing d is 20 μm < d < 70 μm.

[0125] The reason for having a face spacing d greater than 20 μm is to suppress the excessive sensitivity of face spacing deviation when the face spacing is less than 20 μm, which would complicate assembly.

[0126] Therefore, in this embodiment, the surface spacing between lens L5 and object-side lens L61 can be set to a predetermined surface spacing, which can suppress field curvature and improve the performance of the lens unit compared with the prior art. A detailed explanation follows.

[0127] Figures 15 to 18 It is an MTF plot where the horizontal axis represents the defocus distance (nm) and the vertical axis represents the MTF (modulation transfer function) value. Figures 15 to 18 These are the MFT plots for film thicknesses t at the optical design value, 800 nm (0.8 μm), 1100 nm (1.1 μm), and 1600 nm (1.6 μm). The wavelengths of the light used range from 0.4600 (μm) to 0.6563 (μm). The spatial frequency is 80.00 (cycles per millimeter). Figures 15 to 18 In the diagram, A is the tangential MTF curve with a field of view of 0 degrees (optical axis). B is the tangential MTF curve with a field of view of 92.36 degrees relative to the optical axis. The optical design values ​​do not consider film thickness, i.e., film thickness t = 0 nm.

[0128] like Figures 15 to 18 As shown, as the thickness of the antireflective coating 324 between the contact portion 26 of lens L5 and the contacted portion 37 of object-side lens L61 increases, the peak (center) of the tangential MTF curve B with a field of view of 92.36 degrees shifts towards the object side relative to the peak (center) of the tangential MTF curve A with a field of view of 0 degrees, and the shift gradually increases (Z1 < Z2 < Z3 < Z4). Especially when the coating thickness t exceeds 1600 nm (1.6 μm), the shift exceeds 10 μm.

[0129] Within the lens unit, the effect of field curvature increases with the increase of the aforementioned offset. Therefore, it is necessary to minimize the aforementioned offset.

[0130] In this respect, in this embodiment, as described above, the film thickness t1 of the antireflective film 302 deposited on the contact portion 26 of the lens L5 and the film thickness t2 of the antireflective film 304 deposited on the contact portion 37 of the object-side lens L61 satisfy the following conditional expression (3).

[0131] t1+t2<1100nm (3)

[0132] like Figures 15 to 17 As shown, the aforementioned offsets Z1, Z2, and Z3 remain within 10 μm.

[0133] Therefore, in this embodiment, the effect of field curvature can be suppressed, and the performance of the lens unit can be improved compared with the prior art.

[0134] (Camera device)

[0135] Figure 19 This is a schematic diagram of the camera device 350. (For example...) Figure 19 As shown, the camera device 350 includes a lens unit 1, a camera unit 300, and a signal processing unit, which performs calculations on the output signal from the camera unit 300.

[0136] The camera device 350 is an example of a "camera module" of the present disclosure.

[0137] The imaging unit 300 includes an infrared cutoff filter and an imaging element. The imaging element captures the image of the subject formed by the lens unit 1 and converts it into an electrical signal. The imaging element may be, for example, a CCD (charge-coupled device) or CMOS (complementary metal-oxide-semiconductor). The imaging element is configured such that its imaging surface coincides with the image surface of the lens unit 1.

[0138] The camera device 350 can be used, for example, in a vehicle-mounted camera device, specifically in a dashcam. The camera device 350 can capture images of the front, rear, or sides of the vehicle.

[0139] A bandpass filter can be used instead of an infrared cutoff filter.

[0140] (Variation example)

[0141] First variation

[0142] In the above embodiment, the antireflective film 324 is deposited on both the contact portion 26 of the lens L5 and the contacted portion 37 of the object-side lens L61. The technology disclosed herein is not limited thereto.

[0143] For example, the antireflective film 324 can be deposited only on the contact portion 26 of the lens L5. In this case, when the thickness of the antireflective film 324 deposited only on the contact portion 26 of the lens L5 is set to t1, the lens unit preferably satisfies the following condition (5).

[0144] 50nm < t1 < 800nm ​​(5)

[0145] Second variation

[0146] Furthermore, the antireflective film 324 may also be deposited only on the contact portion 37 of the object-side lens L61. In this case, when the thickness of the antireflective film 324 deposited on the contact portion 37 of the object-side lens L61 is set to t2, the lens unit preferably satisfies the following condition (6).

[0147] 50nm < t2 < 800nm ​​(6)

[0148] In the first and second modified examples, the film thicknesses t1 and t2 are greater than 50 nm because if the film thicknesses t1 and t2 are less than 50 nm, there is a tendency to not obtain a sufficient anti-reflection effect. Therefore, by making the film thicknesses t1 and t2 greater than 50 nm, a sufficient anti-reflection effect can be obtained.

[0149] Third variation

[0150] In the above embodiment, when the contact portion 26 of the lens L5 and the contacted portion 37 of the object-side lens L61 are in contact through the anti-reflective film 324, the film thickness t of the anti-reflective film 324 is set to t < 1500 nm, so that when the contact portion 26 and the contacted portion 37 are in contact through the anti-reflective film 324, the surface distance d between the lens L5 and the object-side lens L61 is d < 100 μm.

[0151] The technology disclosed herein is not limited thereto.

[0152] An antireflective film is deposited on lenses L1 and L2, such that the antireflective film between the contact portion of lens L1 and the contacted portion of lens L2 has a film thickness t, such that when the contact portion of lens L1 and the contacted portion of lens L2 are in contact through the antireflective film, the surface distance d between lenses L1 and L2 becomes a predetermined distance. Furthermore, the contact portion of lens L1 and the contacted portion of lens L2 are in contact through the antireflective film on a plane perpendicular to the optical axis L.

[0153] The contact portion of lens L1 is an example of a "part of a first lens" in this disclosure. The contact portion of lens L2 is an example of a "part of a second lens" in this disclosure.

[0154] In the third variation, the interfacial spacing d < 100 μm and the film thickness t < 1500 nm are also present.

[0155] In the third variation, it is even more preferable that the film thickness t is 100 nm < t < 1100 nm.

[0156] In the third variation, it is even more preferable that the surface spacing d is 20 μm < d < 70 μm.

[0157] The antireflective coating can be deposited only on the contact portion of lens L1 or the contacted portion of lens L2. In this case, when the thicknesses of the antireflective coatings deposited on the contact portion of lens L1 and the contacted portion of lens L2 are set as t1 and t2 respectively, it is preferable that 50nm < t1 < 800nm ​​and 50nm < t2 < 800nm.

[0158] Fourth variation

[0159] Furthermore, an anti-reflective film is deposited on lenses L3 and L4, such that the anti-reflective film between the contact portion of lens L3 and the contacted portion of lens L4 has a certain thickness, ensuring that when the contact portion of lens L3 and the contacted portion of lens L4 are in contact through the anti-reflective film, the surface spacing between lenses L3 and L4 is a predetermined distance. Additionally, the contact portion of lens L3 and the contacted portion of lens L4 are in contact through the anti-reflective film on a plane perpendicular to the optical axis L.

[0160] The contact portion of lens L3 is an example of a "part of a first lens" in this disclosure. The contacted portion of lens L4 is an example of a "part of a second lens" in this disclosure.

[0161] In the fourth variation, the interfacial spacing d < 100 μm and the film thickness t < 1500 nm are also present.

[0162] In the fourth variation, it is even more preferable that the film thickness t is 100 nm < t < 1100 nm.

[0163] In the fourth variation, it is even more preferable that the surface spacing d is 20 μm < d < 70 μm.

[0164] The antireflective coating can be deposited only on the contact portion of lens L3 or the contacted portion of lens L4. In this case, when the thicknesses of the antireflective coatings deposited on the contact portion of lens L3 and the contacted portion of lens L4 are set to t1 and t2 respectively, it is preferable that 50nm < t1 < 800nm ​​and 50nm < t2 < 800nm.

[0165] Fifth variation

[0166] Furthermore, the relationships between lens L5 and object-side lens L61, between lens L1 and lens L2, and between lens L3 and lens L4 (the values ​​of surface spacing d and film thickness t) can also be applied between lens L2 and lens L3, and between lens L4 and lens L5.

[0167] Symbol Explanation

[0168] L5 lens

[0169] 24 Lens body

[0170] 25 Flange portion

[0171] 26 Contact Department

[0172] L61 object-side lens

[0173] 35 Lens body

[0174] 36 Flange portion

[0175] 37. Contacted part

[0176] 302 anti-reflective film

[0177] 304 anti-reflective film

[0178] 324 anti-reflective film

[0179] Floors 302N1 to 302N7

[0180] Layers 304N1 to 304N7.

Claims

1. A lens unit, characterized in that, It has a first lens and a second lens. A portion of the first lens and a portion of the second lens are in contact through an anti-reflective film. Let the surface spacing between the first lens and the second lens be d. When the thickness of the antireflective coating between the portion of the first lens and the portion of the second lens is set to t, d < 100 μm t < 1500 nm.

2. The lens unit according to claim 1, characterized in that, The antireflective film is deposited on at least one of the portion of the first lens and the portion of the second lens.

3. The lens unit according to claim 1 or 2, characterized in that, The antireflective film is deposited on the portion of the first lens. When the thickness of the antireflective film deposited on the portion of the first lens is set to t1, 50nm < t1 < 800nm.

4. The lens unit according to claim 1 or 2, characterized in that, The antireflective film is deposited on the portion of the second lens. When the thickness of the antireflective film deposited on the portion of the second lens is set to t2, 50nm < t2 < 800nm.

5. The lens unit according to claim 1 or 2, characterized in that, The antireflective film is deposited on both the portion of the first lens and the portion of the second lens. Let the thickness of the antireflective film deposited on the portion of the first lens be t1. When the thickness of the antireflective film deposited on the portion of the second lens is set to t2, t1+t2<1100nm.

6. The lens unit according to claim 1 or 2, characterized in that, The antireflective film has multiple layers.

7. The lens unit according to claim 6, characterized in that, The film thickness is 100nm < t < 1100nm.

8. The lens unit according to claim 1 or 2, characterized in that, The surface spacing is 20 μm < d < 70 μm.

9. The lens unit according to claim 1 or 2, characterized in that, The surface spacing is the smallest spacing among the surface spacings between the first lens and the second lens.

10. The lens unit according to claim 1 or 2, characterized in that, The surface spacing is the distance between the first lens and the second lens on the optical axis.

11. The lens unit according to claim 1 or 2, characterized in that, The first lens and the second lens each have: a lens surface; and a flange surface disposed on the outer periphery of the lens surface. The portion of the first lens is a portion of the flange surface of the first lens. The portion of the second lens is a portion of the flange surface of the second lens.

12. The lens unit according to claim 1 or 2, characterized in that, The cross-section of the portion of the first lens containing the optical axis is an arc convex toward the second lens. The portion of the second lens is an inclined surface tilted at an angle of more than 45° relative to the optical axis.

13. A camera module, characterized in that, Includes the lens unit as described in claim 1 or 2.

14. A method for manufacturing a lens unit, the lens unit having a first lens and a second lens, characterized in that, This includes making a portion of the first lens and a portion of the second lens contact each other through an anti-reflective film. The thickness of the antireflective film between the portion of the first lens and the portion of the second lens is predetermined, such that when the portion of the first lens and the portion of the second lens are in contact through the antireflective film, the surface spacing between the first lens and the second lens is a predetermined spacing.

15. The method for manufacturing a lens unit according to claim 14, characterized in that, Let the surface spacing between the first lens and the second lens be d. When the thickness of the antireflective film between a portion of the first lens and a portion of the second lens is set to t, d < 100 μm t < 1500 nm.

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