lens unit

Abstract

A lens unit suppresses a decrease in position accuracy of a lens in an optical axis direction due to a heater arranged inside the lens unit. A lens unit (1) includes a plurality of lenses arranged along an optical axis (L) and a lens holder (2). A first lens (L1) positioned closest to an object side (La) includes an object side lens surface (11) and an image side lens surface (12), and an image side flange surface (13) surrounding the image side lens surface (12). In the lens holder (2), a first housing portion (4) housing the first lens (L1) includes a restriction portion (42) that restricts a position of the first lens (L1) in the optical axis (L) direction. The restriction portion (42) includes a lens seat surface (40) that the first lens (L1) abuts against. The image side flange surface (13) of the first lens (L1) includes an outer peripheral region (13A) that the lens seat surface (40) of the restriction portion (42) abuts against, and an inner peripheral region (13B) in which a flexible printed substrate (8) including a heater (9) is arranged.

Description

Technical Field

[0001] This invention relates to a lens unit having multiple lenses arranged on an optical axis. Background Technology

[0002] Patent Document 1 discloses a lens unit for use in an optical device. The lens unit of Patent Document 1 includes multiple lenses arranged on an optical axis and a lens holder for holding the multiple lenses. The lens holder is a molded product that integrally forms a lens barrel (lens barrel) and a housing (front housing) covering the lens barrel. The gap between the first lens, located closest to the subject, and the lens barrel is sealed by an O-ring.

[0003] In the lens unit of Patent Document 1, a heater is provided inside the lens unit to suppress condensation when used outdoors. The heater is an electric heating wire disposed on the surface of a thermally conductive annular flexible printed circuit board (aperture plate). By energizing the electric heating wire, the temperature around the lens is raised.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2019-168509 Summary of the Invention

[0007] The technical problem that the invention aims to solve

[0008] In Patent Document 1, a flexible printed circuit board with a heater is in contact with an annular flat surface disposed on the outer periphery of a first lens. The inner periphery of the flat surface of the first lens faces the outer periphery of the second lens, and the outer periphery faces the lens barrel (the bottom surface of the receiving portion that houses the first lens). Thus, in the structure where the flexible printed circuit board is sandwiched between the first lens and the lens barrel, and between the first lens and the second lens, the positional accuracy of the first lens in the optical axis direction is affected by the thickness tolerance of the flexible printed circuit board. Furthermore, since the flexible printed circuit board is crushed when pressed, thickness deviations increase the amount of crushing. Therefore, there is a problem of reduced positional accuracy of the first lens in the optical axis direction, resulting in inconsistent optical performance of the lens unit.

[0009] In view of the above problems, the objective of the present invention is to suppress the reduction in the positional accuracy of the lens in the optical axis direction caused by the placement of a heater inside the lens unit.

[0010] Technical solutions adopted to solve technical problems

[0011] To address the aforementioned issues, the present invention provides a lens unit, characterized by comprising: a first lens positioned closest to the object side; a second lens disposed on the image side relative to the first lens; a lens holder having a first receiving portion for accommodating the first lens and a second receiving portion for accommodating the second lens; and a flexible printed circuit board having a heater, wherein the first lens has an object-side lens surface, an image-side lens surface, and an image-side flange surface surrounding the image-side lens surface, the first receiving portion having a limiting portion for limiting the position of the first lens in the optical axis direction, and the image-side flange surface having an inner peripheral region for the flexible printed circuit board to be disposed thereon and an outer peripheral region for the limiting portion to abut against.

[0012] According to the present invention, since a flexible printed circuit board equipped with a heater is disposed on the image-side flange surface of the first lens, the temperature around the first lens can be increased. Therefore, condensation inside the lens unit that reduces optical performance can be suppressed. Furthermore, in the present invention, a limiting portion is provided on the lens holder, and the outer peripheral region of the image-side flange surface abuts against the limiting portion. Thus, by providing a structure in which the first lens directly abuts against the lens holder, deviations in the thickness tolerance of the flexible printed circuit board disposed on the image-side flange surface can be avoided from affecting the positional accuracy of the first lens. Therefore, a reduction in the positional accuracy of the first lens due to the placement of the flexible printed circuit board on the image-side flange surface can be avoided.

[0013] In this invention, preferably, the flexible printed circuit board includes a planar portion along the image-side flange surface and an extension portion extending radially outward. The planar portion has a connecting portion connected to the extension portion, and the first receiving portion has a countersunk portion recessed radially outward from the inner periphery of the limiting portion. The connecting portion is disposed in the countersunk portion. This avoids interference between the connecting portion connecting the extension portion for leading the flexible printed circuit board to the outside and the planar portion for arranging the heater and the limiting portion. Therefore, it is possible to avoid a decrease in the positional accuracy of the first lens and to suppress deviations in the optical performance of the lens unit.

[0014] In this invention, it is preferable that the lens holder has a through hole opening on the inner surface of the countersunk portion, and the extension is inserted into the through hole. This prevents interference between the extension, which is provided for extending the flexible printed circuit board to the outside, and the restraining portion. Furthermore, the extension can bend and remain inside the through hole when passing through it. Alternatively, the extension can be fixed to the through hole using an adhesive or the like. Therefore, even if the extension extended to the outside is stretched, its stress is less likely to be transmitted to the connecting portion and the planar portion.

[0015] In this invention, it is preferable to have a transparent conductive film disposed on the image-side lens surface, and the flexible printed circuit board having a protrusion extending radially outward from the planar portion, the protrusion being disposed in the countersunk portion, and an electrode electrically connected to the transparent conductive film disposed on the protrusion. This allows direct heating of the first lens by energizing the transparent conductive film, thus suppressing condensation. Furthermore, since the flexible printed circuit board can be used to supply power to the transparent conductive film, the internal wiring of the lens unit can be kept simple. Moreover, because the electrode for connecting to the transparent conductive film is disposed in the protrusion housed in the countersunk portion, the electrode is prevented from being sandwiched between the lens holder and the first lens. This reduces the possibility of short circuits or other defects caused by crushing of the conductive material constituting the electrode.

[0016] In this invention, it is preferable to have a blackening film formed on the image-side flange surface, and the transparent conductive film having an arm stacked on the blackening film and connected to the electrode via the arm. In this way, because the flexible printed circuit board overlaps with the blackening film, the reduction in optical performance caused by the placement of the flexible printed circuit board can be suppressed. Furthermore, ghosting caused by light transmitted through the image-side flange surface can be suppressed by the blackening film. Additionally, if there are irregularities (wrinkles) on the image-side flange surface for light diffusion, these irregularities (wrinkles) are filled and smoothed by the blackening film. Therefore, it is easy to form the arm of the transparent conductive film on the image-side flange surface. Furthermore, it is easy to form a lead electrode on the image-side flange surface that connects to the electrode on the flexible printed circuit board.

[0017] In this invention, a structure can also be adopted as follows: a metal thin film disposed on the image-side flange surface, the metal thin film being disposed on a circumferential portion of the image-side flange surface, the flexible printed substrate having a protrusion extending radially outward from the planar portion, the protrusion being disposed in the countersunk portion, and the circumferentially forward end of the metal thin film being connected to an electrode disposed on the protrusion. In this way, the image-side flange surface of the first lens can be directly heated via the metal thin film. Furthermore, compared to forming a conductive film on the image-side lens surface, the impact on optical performance due to ghosting and other issues can be reduced.

[0018] In this case, it is preferable to have a blackening film formed on the image-side flange surface, a metal thin film stacked on the blackening film, and a protective film stacked on the metal thin film, wherein the entire extent of the metal thin film, except for the front end, is covered by the protective film, the planar portion is annular, and the planar portion is disposed on the protective film. In this way, because the flexible printed circuit board overlaps with the blackening film, the reduction in optical performance caused by the placement of the flexible printed circuit board can be suppressed. Furthermore, because the blackening film can suppress ghosting caused by light transmitted through the image-side flange surface, the reduction in optical performance due to ghosting can be suppressed. Additionally, because the protective film is stacked on the metal thin film, the metal thin film can be protected. In particular, when under high temperature and high humidity conditions, the metal thin film may oxidize and crack, and its resistance value may change, but by providing the protective film, the formation of cracks can be suppressed. Therefore, changes in resistance value and changes in heat generation can be suppressed. Furthermore, when the flexible printed circuit board is disposed on the first lens, the protective film can be used as a fixing surface for the fixed planar portion.

[0019] In this invention, preferably, the limiting portion includes a plurality of lens mount surfaces that abut against the image-side flange surface, with two of the lens mount surfaces positioned adjacent to the countersunk hole on one circumferential side and another adjacent to the countersunk hole on the other circumferential side. This prevents the first lens from tilting towards the countersunk hole side. Therefore, it is possible to suppress the degradation of the optical performance of the lens unit.

[0020] In this invention, it is preferable that the limiting portion has an outer edge extending circumferentially along the outer periphery of the countersunk portion. This allows the outer edge to support sealing materials such as O-rings. Therefore, by providing the countersunk portion, a reduction in sealing performance can be avoided.

[0021] In this invention, it is preferable that the limiting portion is annular and faces the outer periphery of the first lens along the entire circumferential direction. This allows for the support of sealing materials such as O-rings disposed between the outer periphery of the first lens and the lens holder along the entire circumferential direction. Therefore, the possibility of reduced sealing performance is small. Furthermore, since the lens mount surface can be evenly arranged along the circumferential direction, the possibility of the first lens tilting is small.

[0022] Invention Effects

[0023] According to the present invention, since a flexible printed circuit board equipped with a heater is disposed on the image-side flange surface of the first lens, the temperature around the first lens can be increased. Therefore, condensation inside the lens unit, which could reduce optical performance, can be suppressed. Furthermore, in the present invention, a limiting portion is provided on the lens holder, and the outer peripheral region of the image-side flange surface abuts against the limiting portion. Thus, by providing a structure in which the first lens directly abuts against the lens holder, deviations in the thickness tolerance of the flexible printed circuit board disposed on the image-side flange surface can be avoided from affecting the positional accuracy of the first lens. Therefore, reductions in the positional accuracy of the first lens due to the placement of the flexible printed circuit board on the image-side flange surface can be avoided, and deviations in the optical performance of the lens unit can be suppressed. Attached Figure Description

[0024] Figure 1 This is a cross-sectional view of the lens unit according to an embodiment of the present invention.

[0025] Figure 2 yes Figure 1 A stereoscopic view of the lens unit's components.

[0026] Figure 3 This is a 3D view of the lens holder.

[0027] Figure 4 These are top views of the lens holder and the lens unit with the first lens and O-ring removed.

[0028] Figure 5 This is an explanatory diagram of the heater film, lead-out electrode, and blackening film disposed on the first lens.

[0029] Figure 6 This is a top view of a flexible printed circuit board.

[0030] Figure 7 This is an explanatory diagram showing the arrangement of a flexible printed circuit board and lead-out electrodes in a side flange surface.

[0031] Figure 8 This is a partially enlarged cross-sectional view of the lens unit.

[0032] Figure 9 This is an explanatory diagram of the metal thin film, protective film, and blackening film disposed on the first lens.

[0033] Explanation of reference numerals in the attached figures

[0034] 1…Lens unit; 2…Lens holder; 3…Holder; 4…First receiving part; 5…Second receiving part; 6…Lens housing; 7…O-ring; 8…Flexible printed circuit board; 9…Heater; 11…Object-side lens surface; 12…Image-side lens surface; 13…Image-side flange surface; 13A…Outer peripheral region; 13B…Inner peripheral region; 14…Annular step portion; 15…Blackening film; 16…Transparent conductive film; 16A, 16B…Arm portion; 17A, 17B…Electrode; 18…Metal thin film; 18A, 18B…Front end portion; 19…Protective film; 40…Lens seat surface; 41…Annular connecting part; 42…Restricting part; 43…Peripheral wall portion; 44…Annular end face; 45…Riveting part; 46…Through hole; 47…Counterhole portion; 48…Outer edge portion; 50…Lens seat surface; 51…Cylinder portion; 52… Bottom; 53… Annular bottom surface; 54… Recess; 55… Opening; 56… Riveting part; 80A… Flexible substrate; 80B… Reinforcing plate; 81… Flat part; 82… Extension; 83… Protrusion; 83A… First protrusion; 83B… Second protrusion; 84… Electrode; 84A… First electrode; 84B… Second electrode; 85… Power supply wiring; 85A… First power supply wiring; 85B… Second power supply wiring; 86… Connecting part; 87… Arc part; 88… First notch part; 89… Second notch part; L… Optical axis; La… Object side; Lb… Image side; L1… First lens; L2… Third lens; L3… Third lens; L4… Fourth lens; L5… Fifth lens; L6… Sixth lens; L7… Light shield; L8… Aperture; L9… Joining lens; S… Gap. Detailed Implementation

[0035] Hereinafter, embodiments of the lens unit applying the present invention will be described with reference to the accompanying drawings.

[0036] (Overall structure)

[0037] Figure 1 This is a cross-sectional view of the lens unit 1 according to an embodiment of the present invention. Figure 1 In the diagram, L is the optical axis of lens unit 1. La is one side of the optical axis L, which is the object side (subject side) of lens unit 1. Lb is the other side of the optical axis L, which is the image side of lens unit 1. Lens unit 1 includes a plurality of lenses arranged in a row along the optical axis L and a lens holder 2 for holding the plurality of lenses. The plurality of lenses includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, and a sixth lens L6. A light-shielding plate L7 is disposed between the second lens L2 and the third lens L3, and an aperture L8 is disposed between the third lens L3 and the fourth lens L4.

[0038] Of the multiple lenses, the first lens L1 and the fourth lens L4, located closest to the object side La, are glass lenses. The fourth lens L4 is disposed inside the lens holder 2 and fixed to the frame-shaped bracket 3. The second lens L2, the third lens L3, the fifth lens L5, and the sixth lens L6 are plastic lenses. The sixth lens L6 and the fifth lens L5, located closest to the image side Lb, constitute a combined lens L9. Furthermore, the number and structure of the lenses held in the lens holder 2 are not limited to the numbers and structures described above.

[0039] The lens holder 2 is made of resin. The lens holder 2 includes a first receiving portion 4 that holds the first lens L1, a second receiving portion 5 disposed on the image side Lb of the first receiving portion 4, and a lens housing 6 surrounding the outer periphery of the second receiving portion 5. The lens housing 6 extends from the outer periphery of the first receiving portion 4 toward the image side Lb. The second receiving portion 5 holds the second lens L2, the third lens L3, the fourth lens L4, and the joining lens L9 (the fifth lens L5 and the sixth lens L6).

[0040] Figure 2 yes Figure 1 A stereoscopic view of the dissection of lens unit 1. Figure 3 This is a 3D view of lens holder 2. Figure 4 (a) is a top view of lens holder 2. Figure 4 (b) is a top view of lens unit 1 with the first lens L1 and O-ring 7 removed. Figure 3 , Figure 4 It is an omission of the ratio Figure 1 The diagram shows the upper part (riveting part 45) of position A-A. Figure 1 , Figure 2 As shown, a first lens L1 is disposed on the lens holder 2 with reference to the inner peripheral surface of the first receiving portion 4. In addition, a second lens L2, a third lens L3, a fourth lens L4, and a joint lens L9 (a fifth lens L5 and a sixth lens L6) are disposed with reference to the inner peripheral surface of the second receiving portion 5.

[0041] The first lens L1 is positioned along the optical axis L using the lens mount surface 40 formed at the bottom of the first receiving portion 4 as a reference. For example... Figure 1 , Figure 3 As shown, the bottom of the first receiving portion 4 has an annular connecting portion 41 that is connected to the outer peripheral surface of the second receiving portion 5, an annular limiting portion 42 that protrudes from the outer peripheral side of the annular connecting portion 41 toward the object side La, and a peripheral wall portion 43 that rises from the outer peripheral edge of the limiting portion 42 toward the object side La.

[0042] like Figure 3 , Figure 4As shown, the limiting portion 42 has protrusions at multiple locations that slightly protrude from the annular end face 44 facing the object side La, and the front end face of each protrusion is a lens mount surface 40. In this configuration, the lens mount surface 40 is provided at four locations spaced approximately at equal angles around the optical axis L. The outer peripheral portion of the first lens L1 abuts against the lens mount surface 40, and the first lens L1 is riveted and fixed by a riveting portion 45 provided at the front end of the peripheral wall portion 43. The gap between the first lens L1 and the first receiving portion 4 is sealed by an O-ring 7.

[0043] like Figure 1 , Figure 2 As shown, the second receiving portion 5 includes a cylindrical portion 51 connected to the annular connecting portion 41 of the first receiving portion 4 and a bottom portion 52 disposed at the image-side Lb end of the cylindrical portion 51 extending along the optical axis L. The second lens L2, the third lens L3, the fourth lens L4, and the combined lens L9 (the fifth lens L5 and the sixth lens L6) are formed on the lens mount surface 50 of the bottom 52 of the second receiving portion 5 (see reference). Figure 3 , Figure 4 (a) is positioned in the direction of the optical axis L as a reference.

[0044] The bottom 52 of the second receiving portion 5 has protrusions at multiple locations that slightly protrude from the annular bottom surface 53 facing the object side La, and the front end surface of each protrusion is a lens seat surface 50. For example... Figure 4 As shown in (a), in this embodiment, lens mount surfaces 50 are provided at three locations spaced approximately at equal angles around the optical axis L. Additionally, the second receiving portion 5 includes a recess 54 recessed to the image side Lb at a predetermined depth on the inner circumferential side of the annular bottom surface 53, and a circular opening 55 located at the center of the recess 54.

[0045] The fifth lens L5 abuts against the lens mount surface 50, and the joining lens L9 is positioned in the optical axis L direction. The sixth lens L6, which is located closest to the image side Lb, is accommodated inside the recess 54, but does not contact the inner surface of the recess 54. Instead, it is positioned in the optical axis L direction via the fifth lens L5.

[0046] The fourth lens L4, located on the object side La of the bonding lens L9, is held in place by the bracket 3, which abuts against the outer peripheral portion of the fifth lens L5 in the optical axis L direction. Furthermore, the outer peripheral portion of the third lens L3, located on the object side La of the fourth lens L4, abuts against the outer peripheral portion of the bracket 3 in the optical axis L direction via the aperture L8. Additionally, the outer peripheral portion of the second lens L2, located on the object side La of the third lens L3, abuts against the outer peripheral portion of the third lens L3 in the optical axis L direction via the light-shielding plate L7. Therefore, the second lens L2, the third lens L3, and the fourth lens L4 are all positioned in the optical axis L direction with the lens mount surface 50 as a reference. The second lens L2 is riveted and fixed by a riveting portion 56 provided at the end of the cylindrical portion 51 on the object side La.

[0047] (Transparent conductive film)

[0048] Lens unit 1 includes a transparent conductive film 16 disposed on the surface of the first lens L1. The transparent conductive film 16 is a resistive element that heats up when energized, acting as a heater to directly heat the first lens L1. Figure 1 , Figure 2 As shown, the first lens L1 includes an object-side lens surface 11 protruding towards the object side La, an image-side lens surface 12 recessed towards the object side La, an image-side flange surface 13 surrounding the outer periphery of the image-side lens surface 12, and an annular step portion 14 recessed towards the object side La on the outer periphery of the image-side flange surface 13. The image-side flange surface 13 is an annular flat surface perpendicular to the optical axis L. An O-ring 7 is disposed in the annular step portion 14.

[0049] Figure 5 This is an explanatory diagram of the transparent conductive film 16, the lead-out electrodes 17A and 17B, and the blackening film 15 disposed on the first lens L1. Figure 5 (a)~ Figure 5 (d) is a top view of the first lens L1 as seen from the image side Lb. Figure 5 (a) represents the planar shape of the blackening film 15. Figure 5 (b) indicates the planar shape of the transparent conductive film 16. Figure 5 (c) indicates the planar shape of the lead-out electrodes 17A and 17B. Figure 5 (d) indicates the state in which the transparent conductive film 16, lead-out electrodes 17A and 17B and blackening film 15 are stacked on the image-side lens surface 12 and the image-side flange surface 13.

[0050] The image-side flange surface 13 is a light-diffusing surface, and minute irregularities (wrinkles) are formed on its entire surface. In this embodiment, a blackening film 15 is formed on the image-side flange surface 13. The blackening film 15 is formed, for example, by applying ink. Since the first lens L1 diffuses light through the minute irregularities (wrinkles) and absorbs light through ink application, the degradation of optical performance due to ghosting can be suppressed. Figure 5 As shown in (a), the blackening film 15 is formed on almost the entire surface of the image side flange surface 13.

[0051] A transparent conductive film 16 is disposed on the image-side lens surface 12. In this embodiment, the transparent conductive film 16 is an ITO film. The deposition process of the transparent conductive film 16 relative to the image-side lens surface 12 is performed after the blackening film 15 is formed on the image-side flange surface 13. In the lens unit 1, the image-side lens surface 12 is uniformly heated by energizing the transparent conductive film 16. Power is supplied to the transparent conductive film 16 via lead-out electrodes 17A and 17B disposed on the image-side flange surface 13.

[0052] like Figure 5As shown in (b), the transparent conductive film 16 has two arms 16A and 16B disposed on the image-side flange surface 13. Arms 16A and 16B extend from the outer periphery of the image-side lens surface 12 in two radially opposite directions. Lead-out electrodes 17A and 17B are arranged symmetrically about the optical axis L. Lead-out electrode 17A extends in an arc shape circumferentially about the front end of arm 16A. Arms 16A and 16B and lead-out electrodes 17A and 17B are stacked on the blackening film 15.

[0053] (Flexible printed circuit board)

[0054] like Figure 1 , Figure 2 As shown, the lens unit 1 includes a flexible printed circuit board 8. The flexible printed circuit board 8 extends radially outward from between the first lens L1 and the second lens L2 and is bent at approximately a right angle, passing through a through hole 46 formed on the first receiving portion 4 of the lens holder 2, and is led out to the image side Lb of the lens holder 2.

[0055] A power supply wiring 85 and an electrode 84 for supplying power to the transparent conductive film 16 are disposed on the flexible printed circuit board 8. Additionally, a heater 9 is disposed on the flexible printed circuit board 8. That is, in this embodiment, heating elements (heaters) are respectively provided at both the first lens L1 and the flexible printed circuit board 8.

[0056] Figure 6 This is a top view of the flexible printed circuit board 8. The flexible printed circuit board 8 includes an annular planar portion 81 along the image-side flange surface 13, an extension portion 82 extending linearly from the planar portion 81 toward the radially outward direction, and protrusions 83 protruding radially outward from the planar portion 81 on both sides of the extension portion 82 in the circumferential direction. A heater 9 is disposed in the planar portion 81. The area where the heater 9 is disposed, for example, is... Figure 6 Region B is enclosed by a dashed line. A pattern of conductive material that heats up when electricity is applied is formed in region B (illustration omitted).

[0057] An electrode 84 is disposed on the protrusion 83 of the flexible printed circuit board 8, and the electrode 84 is electrically connected to the lead-out electrodes 17A and 17B disposed on the first lens L1. Additionally, a power supply line 85 connected to the electrode 84 and the heater 9 is disposed on the extension 82. More specifically, the protrusion 83 has a first protrusion 83A disposed on one side of the extension 82 in the circumferential direction and a second protrusion 83B disposed on the other side of the extension 82 in the circumferential direction. The electrode 84 has a first electrode 84A disposed on the first protrusion 83A and a second electrode 84B disposed on the second protrusion 83B. The power supply line 85 has a first power supply line 85A connected to the first electrode 84A and a second power supply line 85B connected to the second electrode 84B. One of the first electrode 84A and the second electrode 84B is a positive electrode, and the other of the first electrode 84A and the second electrode 84B is a negative electrode.

[0058] The planar portion 81 of the flexible printed circuit board 8 includes a connecting portion 86 disposed radially inward of the extension portion 82 and arcuate portions 87 extending circumferentially on both sides of the connecting portion 86. The arcuate portions 87 are connected to the extension portion 82 via the connecting portion 86. Protrusions 83 protrude radially outward from the arcuate portions 87 on both sides of the connecting portion 86 in the circumferential direction.

[0059] The first power supply line 85A and the second power supply line 85B extend substantially parallel to each other in an electrically insulated manner at the extension 82, and extend in opposite directions in the circumferential direction at the connecting portion 86. The first power supply line 85A, extending circumferentially to one side, extends radially outward toward the first protrusion 83A and connects to the first electrode 84A. Conversely, the second power supply line 85B, extending circumferentially to the other side, extends radially outward toward the second protrusion 83B and connects to the second electrode 84B. Furthermore, in... Figure 6 The diagram only shows the arrangement area of ​​electrode 84 and power supply wiring 85; detailed structures of electrode 84 and power supply wiring 85 are omitted. Electrode 84 can be disposed on protrusion 83, and its arrangement area is not limited to this. Figure 6 The area shown. Furthermore, the configuration area for power supply wiring 85 is not limited to... Figure 6 The area shown.

[0060] The flexible printed circuit board 8 includes a flexible substrate 80A made of a resin film such as polyimide and a pattern of wiring or electrodes formed on the flexible substrate 80A using a conductive material such as Cu. In this embodiment, electrodes 84 for energizing the transparent conductive film 16, power supply wiring 85 for energizing the transparent conductive film 16 and the heater 9, and a pattern of conductive material that functions as the heater 9 are formed on the flexible substrate 80A. The conductive material pattern is coated onto the surface of the flexible substrate 80A. However, a portion of the conductive material pattern is exposed and not coated. For example, the electrodes 84 for electrical connection with the transparent conductive film 16 are not covered by the coating.

[0061] The flexible printed circuit board 8 includes a first notch 88 formed by making a straight cut in the radially inward direction at the portion adjacent to the protrusion 83 in the circumferential direction. More specifically, the first notch 88 is provided at two locations: between the first protrusion 83A and the extension 82, and between the second protrusion 83B and the extension 82. By providing the first notch 88, warping of the first protrusion 83A and the second protrusion 83B is suppressed. In addition, the electrode 84 and the power supply wiring 85 are less prone to short circuits.

[0062] Furthermore, the flexible printed circuit board 8 includes a second notch 89 formed by making a straight cut along the inner periphery of the connecting portion 86 radially outward. The second notch 89 is located approximately at the center of the circumference of the extension 82 and is disposed between the first power supply line 85A and the second power supply line 85B. By providing the second notch 89, warping of the connecting portion 86 is suppressed, and short circuits between the first power supply line 85A and the second power supply line 85B are less likely to occur.

[0063] In this configuration, the first notch 88 and the second notch 89 are used as adhesive coating grooves. When assembling the lens unit 1, the flexible printed circuit board 8 is fixed to the image-side flange surface 13 by the adhesive disposed in the first notch 88 and the second notch 89.

[0064] Figure 7 This is an explanatory diagram showing the arrangement of the flexible printed circuit board 8 and the lead electrodes 17A and 17B in the side flange surface 13. (See diagram below.) Figure 7 As shown, when fixing the planar portion 81 of the flexible printed circuit board 8 to the image-side flange surface 13, the planar portion 81 is positioned such that the center of the image-side flange surface 13 coincides with the center of the planar portion 81. The shape of the planar portion 81 is set to a shape that has little impact on the optical performance of the lens unit 1. In this embodiment, the inner diameter D1 of the planar portion 81 is a predetermined size (e.g., 0.4 mm) larger than the inner diameter D2 of the image-side flange surface 13. Therefore, the possibility of the inner periphery of the planar portion 81 being exposed inside the image-side lens surface 12, thus reducing the optical performance, is small.

[0065] When the planar portion 81 is fixed to the image-side flange surface 13, the planar portion 81 is positioned in the circumferential direction so that the second notch portion 89, which is located at the center in the width direction of the extension portion 82, is positioned at the center of the circumferential gap between the two lead-out electrodes 17A and 17B. Thus, the first electrode 84A and the lead-out electrode 17A overlap, and the second electrode 84B and the lead-out electrode 17B overlap. Therefore, the power supply wiring 85 is electrically connected to the transparent conductive film 16 via the arms 16A and 16B and the lead-out electrodes 17A and 17B.

[0066] In this configuration, since the lead-out electrodes 17A and 17B extend circumferentially, the power supply positions to lead-out electrodes 17A and 17B can be made close together. Therefore, the first electrode 84A and the second electrode 84B, which are connected to lead-out electrodes 17A and 17B, can be concentrated near the extension portion 82. This shortens the power supply wiring 85 provided between the extension portion 82 and the first electrode 84A and the second electrode 84B, and allows for a simpler shape.

[0067] (Positioning of the first lens along the optical axis L)

[0068] Figure 8 This is a partially enlarged cross-sectional view of lens unit 1. Figure 4 (b) Diagram showing the C-C cutoff point. (See diagram below.) Figure 8 As shown, the lens holder 2 has a limiting portion 42 protruding from the bottom of the first receiving portion 4 towards the object side La. The image-side flange surface 13 of the first lens L1 has an outer peripheral region 13A that abuts against the lens seat surface 40 disposed at the front end of the limiting portion 42. In addition, the image-side flange surface 13 has an inner peripheral region 13B located on the inner peripheral side of the outer peripheral region 13A, and the planar portion 81 of the flexible printed circuit board 8 is disposed in the inner peripheral region 13B.

[0069] When the first lens L1 is installed into the first receiving part 4, as Figure 4 (b) Figure 8 As shown, the planar portion 81 disposed in the inner peripheral region 13B of the image-side flange surface 13 is disposed on the inner peripheral side of the limiting portion 42. Therefore, the planar portion 81 will not interfere with the limiting portion 42, and the flexible printed circuit board 8 will not be sandwiched between the first lens L1 and the lens holder 2. In this configuration, the position of the first lens L1 in the optical axis L direction is defined by the direct contact between the outer peripheral region 13A of the image-side flange surface 13 and the lens seat surface 40.

[0070] like Figure 8As shown, the planar portion 81 of the flexible printed circuit board 8 extends radially outward from the riveting portion 56 that fixes the outer periphery of the second lens L2. In this configuration, the gap S between the riveting portion 56 and the inner peripheral region 13B of the image-side flange surface 13 in the optical axis L direction is greater than the thickness of the flexible printed circuit board 8. Therefore, the planar portion 81 does not interfere with the riveting portion 56, and the flexible printed circuit board 8 is not sandwiched between the first lens L1 and the riveting portion 56.

[0071] (Counter-sunken section)

[0072] like Figure 2 , Figure 3 , Figure 4 As shown, the first receiving portion 4 has a countersunk portion 47 that is recessed radially outward from the inner periphery of the limiting portion 42. As... Figure 4 As shown in (b), the extension 82 and protrusion 83 of the flexible printed circuit board 8 are disposed in the countersunk hole portion 47. Additionally, as... Figure 2 As shown, the extension 82 bends towards the image side Lb midway through its radially outward extension and is inserted into the slit-shaped through hole 46, which is an opening on the bottom surface of the countersunk hole 47. Therefore, the extension 82 and the protrusion 83 do not interfere with the limiting portion 42. Furthermore, the extension 82 may also include a reinforcing plate 80B fixed to the flexible substrate 80A. When the reinforcing plate 80B is included, it is disposed within the through hole 46.

[0073] like Figure 1 , Figure 2 As shown, the through hole 46 extends through the bottom of the first receiving portion 4 along the optical axis L, communicating with the gap between the cylindrical portion 51 of the second receiving portion 5 and the lens housing 6. The inner circumferential surface of the lens housing 6 is recessed in shape along the radially outer edge of the through hole 46. The extension 82 inserted into the through hole 46 passes through the gap between the inner circumferential surface of the lens housing 6 and the outer circumferential surface of the cylindrical portion 51, and is led out to the image side Lb of the lens holder 2.

[0074] In this method, the extension 82 is not fixed in the through hole 46, but an adhesive can be placed in the through hole 46 to fix the extension 82 to the through hole 46. In this case, by pre-forming unevenness on the inner circumferential surface of the through hole 46, the bonding area can be increased, and the fixing strength of the extension 82 can be improved.

[0075] The limiting portion 42 includes an outer edge 48 extending circumferentially outward from the countersunk portion 47. The outer edge 48 is connected to lens mount surfaces 40 provided on both circumferential sides of the countersunk portion 47. Therefore, in this configuration, the limiting portion 42 is generally annular and is opposed to the outer periphery of the first lens L1 throughout the circumferential direction. Thus, since the O-ring 7 disposed on the outer periphery of the first lens L1 is supported by the limiting portion 42 throughout the circumferential direction, the O-ring 7 is prevented from falling into the inner side of the countersunk portion 47, thereby reducing the sealing performance.

[0076] (The main effects of this method)

[0077] As described above, the lens unit 1 of this embodiment includes a first lens L1 located closest to the object side La, a second lens L2 disposed on the image side Lb relative to the first lens L1, a lens holder 2 having a first receiving portion 4 for accommodating the first lens L1 and a second receiving portion 5 for accommodating the second lens L2, and a flexible printed circuit board 8 having a heater 9. The first lens L1 has an object-side lens surface 11, an image-side lens surface 12, and an image-side flange surface 13 surrounding the image-side lens surface 12. The first receiving portion 4 has a limiting portion 42 that restricts the position of the first lens L1 in the optical axis L direction. The image-side flange surface 13 has an inner peripheral region 13B on which the flexible printed circuit board 8 is disposed and an outer peripheral region 13A for the limiting portion 42 to abut against.

[0078] Since the lens unit 1 of this embodiment has a flexible printed circuit board 8 equipped with a heater 9 disposed on the image-side flange surface 13 of the first lens L1, the temperature around the first lens L1 can be increased. Therefore, condensation inside the lens unit 1, which would otherwise reduce optical performance, can be suppressed. Furthermore, the outer peripheral region 13A of the first lens L1 directly abuts against the limiting portion 42 provided on the lens holder 2, preventing the flexible printed circuit board 8 from being sandwiched between the first lens L1 and the lens holder 2. Therefore, deviations in the thickness tolerance of the flexible printed circuit board 8 can be avoided from affecting the positional accuracy of the first lens L1. Thus, a decrease in the positional accuracy of the first lens L1 can be avoided, and deviations in optical performance can be suppressed.

[0079] The flexible printed circuit board 8 of this embodiment includes a planar portion 81 along the image-side flange surface 13 and an extension portion 82 extending radially outward. The planar portion 81 has a connecting portion 86 connected to the extension portion 82. The first receiving portion 4 has a countersunk portion 47 recessed radially outward from the inner periphery of the limiting portion 42, and the connecting portion 86 is disposed in the countersunk portion 47. Therefore, the connecting portion 86 connecting the extension portion 82 for extending the flexible printed circuit board 8 outward and the planar portion 81 for disposing of the heater 9 can be arranged in a manner that does not interfere with the limiting portion 42. As a result, the reduction in the positional accuracy of the first lens L1 due to the flexible printed circuit board 8 being disposed on the image-side flange surface 13 can be avoided.

[0080] In this embodiment, a transparent conductive film 16 (conductive film) is disposed on the image-side lens surface 12 of the first lens L1. The flexible printed circuit board 8 has a protrusion 83 that protrudes radially outward from the planar portion 81. The protrusion 83 is disposed in the countersunk hole portion 47. Furthermore, an electrode 84 electrically connected to the transparent conductive film 16 is disposed in the protrusion 83. Therefore, in this embodiment, since the transparent conductive film 16 can be heated to directly heat the lens surface of the first lens L1, condensation can be suppressed. Additionally, since the flexible printed circuit board 8 can be used to supply power to the transparent conductive film 16, complex wiring within the lens unit 1 can be avoided. Furthermore, since the electrode 84 for connecting to the transparent conductive film 16 is disposed in the protrusion 83 housed in the countersunk hole portion 47, the electrode 84 is prevented from being sandwiched between the lens holder 2 and the first lens L1. Therefore, the possibility of defects such as short circuits caused by crushing of the conductive material constituting the electrode 84 is small.

[0081] In this embodiment, a blackening film 15 is formed on the image-side flange surface 13 where the flexible printed circuit board 8 is disposed. Therefore, since the blackening film 15 overlaps with the flexible printed circuit board 8, the impact of the flexible printed circuit board 8 on optical performance is minimal. Furthermore, since the blackening film 15 can suppress ghosting caused by light transmitted through the image-side flange surface 13, the reduction in optical performance due to ghosting can be suppressed. In this embodiment, the transparent conductive film 16 has arms 16A and 16B stacked on the blackening film 15, and is connected to the electrode 84 via the arms 16A and 16B. Thus, if the transparent conductive film 16 is formed on the blackening film 15, it is easy to form the transparent conductive film 16. For example, if the image-side flange surface 13 has irregularities (wrinkles) for light diffusion, the blackening film 15 fills in the irregularities (wrinkles) and smooths the surface. Therefore, the arms 16A and 16B of the transparent conductive film 16 can be easily formed on the image-side flange surface 13.

[0082] In this configuration, the limiting portion 42 includes a plurality of lens mount surfaces 40 that abut against the image-side flange surface 13. Two of the lens mount surfaces 40 are positioned adjacent to the countersunk hole portion 47 on one side of the circumferential direction and on the other side of the circumferential direction. Thus, by supporting the first lens L1 on both sides of the countersunk hole portion 47, tilting of the first lens L1 toward the countersunk hole portion 47 can be prevented. Therefore, a decrease in the optical performance of the lens unit 1 can be suppressed.

[0083] In this configuration, the limiting portion 42 is annular and faces the outer periphery of the first lens L1 along the entire circumferential direction. Therefore, sealing materials such as the O-ring 7 disposed between the outer periphery of the first lens L1 and the lens holder 2 can be supported along the entire circumferential direction, thus minimizing the possibility of reduced sealing performance. Furthermore, by making the limiting portion 42 annular, the lens mount surface 40 can be evenly arranged along the circumferential direction. Therefore, tilting of the first lens L1 can be avoided, and a decrease in the optical performance of the lens unit 1 can be suppressed.

[0084] In this embodiment, the limiting part 42 has an outer edge 48 extending circumferentially on the outer periphery of the countersunk hole part 47. Therefore, since the O-ring 7 can be supported by the outer edge 48, it is possible to prevent the O-ring 7 from falling into the inner side of the countersunk hole part 47 and thus reducing the sealing performance.

[0085] (Modified Example)

[0086] (1) In the above-described manner, a transparent conductive film 16 that functions as a heater is provided on the image-side lens surface 12, but the transparent conductive film 16 may not be provided. In this case, it is not necessary to provide lead-out electrodes 17A and 17B on the image-side flange surface 13. In addition, it is not necessary to provide electrodes 84 for supplying power to the transparent conductive film 16 on the flexible printed circuit board 8.

[0087] (2) In the above manner, the planar portion 81 of the flexible printed substrate is annular, but it may also be a shape in which a portion of the circumferential portion 81 is missing.

[0088] (3) The above method is to use a transparent conductive film 16 such as ITO film as a conductive film to directly heat the first lens L1 and place it on the image side (image side lens surface 12, image side flange surface 13) of the first lens L1. However, it is also possible to use a structure in which other conductive films are placed on the image side of the first lens L1. Figure 9 This is an explanatory diagram of the metal thin film 18, the protective film 19, and the blackening film 15 disposed on the first lens L1. Figure 9 (a)~ Figure 9 (d) is a top view of the first lens L1 as seen from the image side Lb.

[0089] Figure 9 (a) represents the planar shape of the blackening film 15. Figure 9 (b) represents the planar shape of the metal thin film 18. Figure 9 (c) indicates the planar shape of the protective film 19. Figure 9 (d) indicates the state in which the metal thin film 18, the protective film 19 and the blackening film 15 are stacked on the image-side flange surface 13.

[0090] The metal thin film 18 is a conductive film disposed on the image-side flange surface 13 of the first lens L1. The metal thin film 18 is, for example, a laminated film formed by stacking NiFe films, Ni films, or Cr films, or Ni and Cr films. The metal thin film 18 is stacked on the blackening film 15. Figure 9 As shown in (b), the metal film 18 is disposed on a portion of the circumferential direction of the image-side flange surface 13. In this configuration, the metal film 18 extends in an arc shape on the image-side flange surface 13, forming a C-shaped planar shape. The front end portion 18A on one side of the circumferential direction of the metal film 18 and the front end portion 18B on the other side of the circumferential direction of the metal film 18 are spaced apart by a predetermined gap and face each other in the circumferential direction.

[0091] The protective film 19 has low moisture permeability, thus protecting the metal film 18 from moisture. The protective film 19 is preferably a non-conductive film such as a SiO2 film. The protective film 19 is laminated on the metal film 18. Figure 9 As shown in (c), the protective film 19, like the metal film 18, is formed in a C-shaped planar shape. The protective film 19 extends over the entire radial range from the inner to the outer periphery of the image-side flange surface 13, but the angular range where the protective film 19 is disposed is smaller than the angular range where the metal film 18 is disposed. Therefore, as... Figure 9 As shown in (d), except for the front ends 18A and 18B, the entire extent of the metal film 18 is covered by the protective film 19.

[0092] In the lens unit 1, the image-side flange surface 13 is heated by energizing the metal thin film 18. Power is supplied to the metal thin film 18 via the exposed front portions 18A and 18B of the protective film 19. When the planar portion 81 of the flexible printed circuit board 8 is placed on the protective film 19 disposed on the image-side flange surface 13, the electrode 84 provided on the protrusion 83 protruding from the planar portion 81 contacts the front portions 18A and 18B of the metal thin film 18. Therefore, the metal thin film 18 is energized via the electrode 84.

[0093] Thus, in Figure 9 In the modified example shown, since the image-side flange surface 13 of the first lens can be directly heated through the metal thin film 18, condensation inside the lens unit 1, which would otherwise reduce optical performance, can be suppressed. Furthermore, compared to the case where a transparent conductive film 16 is formed on the image-side lens surface 12, the impact on optical performance due to ghosting and other issues can be reduced.

[0094] In addition, Figure 9In the modified example shown, similarly to the above method, since the flexible printed circuit board 8 overlaps with the blackening film 15, the reduction in optical performance caused by the placement of the flexible printed circuit board 8 can be suppressed. Furthermore, since the blackening film 15 can suppress ghosting caused by light transmitted through the image-side flange surface 13, the reduction in optical performance due to ghosting can be suppressed. Additionally, since the metal thin film 18 can be protected by the protective film 19, environmental resistance can be improved. In particular, when high temperature and high humidity conditions are reached, the metal thin film 18 may oxidize and crack, causing a change in resistance value; however, by protecting the metal thin film 18 with the protective film 19, the formation of cracks can be suppressed. Therefore, the change in the resistance value of the metal thin film 18 can be suppressed, and deviations in heat generation can be suppressed. Furthermore, when the flexible printed circuit board 8 is placed on the first lens, the protective film 19 can be used as the fixing surface of the fixing plane portion 81.

Claims

1. A lens unit, characterized in that, have: The first lens is positioned closest to the object side; The second lens is disposed on the image side relative to the first lens; The lens holder includes a first receiving portion for accommodating the first lens and a second receiving portion for accommodating the second lens; and A flexible printed circuit board, wherein the flexible printed circuit board includes a heater. The first lens has an object-side lens surface, an image-side lens surface, and an image-side flange surface surrounding the image-side lens surface. The first receiving portion of the lens holder includes a limiting portion that restricts the position of the first lens in the optical axis direction. The limiting portion has protrusions at multiple locations that project from an annular end face toward the object side. The front end face of each of the aforementioned protrusions is a lens mount surface that positions the first lens along the optical axis. The flexible printed substrate has a planar portion along the image-side flange surface of the first lens and an extension portion extending radially outward. The planar portion of the flexible printed circuit board has a connecting portion that connects to the extension portion of the flexible printed circuit board. The image-side flange surface of the first lens has an inner peripheral region for the planar portion of the flexible printed circuit board to be disposed thereon, and an outer peripheral region for the lens mount surface to abut against the image side from the optical axis direction. The first receiving portion of the lens holder has a countersunk portion that is recessed radially outward from the inner periphery of the limiting portion of the first receiving portion. The connecting portion of the flexible printed circuit board is disposed in the countersunk portion of the first receiving portion of the lens holder.

2. The lens unit according to claim 1, characterized in that, The lens holder has a through hole that opens on the inner surface of the countersunk portion of the first receiving portion. The extension of the flexible printed substrate is inserted into the through hole of the countersunk portion of the first receiving portion of the lens holder.

3. The lens unit according to claim 1 or 2, characterized in that, It has a transparent conductive film disposed on the image-side lens surface of the first lens. The flexible printed circuit board has a protrusion that protrudes radially outward from the planar portion of the flexible printed circuit board. The protrusion of the flexible printed circuit board is disposed in the countersunk portion of the first receiving portion of the lens holder. An electrode electrically connected to the transparent conductive film is disposed on the protrusion of the flexible printed substrate.

4. The lens unit according to claim 3, characterized in that, It has a blackening film formed on the image-side flange surface of the first lens. The transparent conductive film has an arm stacked on the blackened film and is connected to the electrode via the arm.

5. The lens unit according to claim 1 or 2, characterized in that, It has a thin metal film disposed on the image-side flange surface of the first lens. The metal thin film is disposed on a portion of the circumferential side flange surface of the first lens. The flexible printed circuit board has a protrusion that protrudes radially outward from the planar portion of the flexible printed circuit board. The protrusion of the flexible printed circuit board is disposed in the countersunk portion of the first receiving portion of the lens holder. The circumferential front end of the metal film is connected to the electrode of the protrusion disposed on the flexible printed substrate.

6. The lens unit according to claim 5, characterized in that, It has a blackening film formed on the image-side flange surface of the first lens. The metal film is laminated on the blackened film. A protective film is laminated on the metal film, covering the entire extent of the metal film except for the front end. The planar portion of the flexible printed substrate is annular, and the planar portion of the flexible printed substrate is disposed on the protective film.

7. The lens unit according to claim 1 or 2, characterized in that, The limiting portion of the first receiving portion of the lens holder has a plurality of lens seat surfaces that abut against the image-side flange surface of the first lens. Two of the lens mount surfaces of the limiting portion of the first receiving portion are arranged at positions adjacent to the countersunk portion of the first receiving portion on one side of the circumferential direction and adjacent to the countersunk portion of the first receiving portion on the other side of the circumferential direction.

8. The lens unit according to claim 1 or 2, characterized in that, The limiting portion of the first receiving portion of the lens holder has an outer edge portion that extends circumferentially outward from the countersunk portion of the first receiving portion.

9. The lens unit according to claim 1 or 2, characterized in that, The limiting portion of the first receiving portion of the lens holder is annular and is opposed to the outer periphery of the first lens in the entire circumferential direction.

Images