Lens unit and camera module

Abstract

To provide a lens unit and a camera module which allow an FPC heater for heating a first lens positioned closest to an object to get a desired heating value and which improve reliability of circuit patterns of the FPC heater.SOLUTION: A lens unit includes: a plurality of lenses 13 to 17 arrayed along an optical axis; a lens barrel 12 for storing and holding the plurality of lenses 13 to 17; and an FPC heater 50 capable of heating the first lens 13 positioned closest to an object. The FPC heater 50 includes a heating part 51 for heating the first lens 13. The heating part 51 includes a plurality of circuit layers 72 in which circuit patterns 71 are formed by copper films 70, so that the FPC heater 50 can get a desired heating value and the reliability of the circuit patterns 71 of the FPC heater 50 is improved.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The present invention relates to a lens unit and a camera module that can constitute an in-vehicle camera mounted on a vehicle such as an automobile.

Background Art

[0002] Cameras installed outdoors, such as surveillance cameras and in-vehicle cameras, are known. In such cameras installed outdoors, ice and snow may adhere to the front surface of the lens during snowfall. Also, when the outside air temperature drops below the freezing point, the front surface of the lens may freeze and frost may adhere. In that case, the imaging image becomes unclear due to the deposits on the front surface of the lens, and the imaging performance of the camera deteriorates. In recent years, cameras (in-vehicle cameras) have been mounted on vehicles, and the images captured by the in-vehicle cameras are used for functions such as an automatic braking function and an automatic driving function. These functions are functions for controlling the running of the vehicle, and a deterioration in the imaging function of the in-vehicle camera may lead to the occurrence of accidents and the like. Therefore, there is a demand for the development of a camera equipped with a snow melting function for melting the deposits adhering to the front surface of the lens. In addition, since the lens unit of the in-vehicle camera is in a state where the side facing the imaging target (object side) is exposed to the outside of the vehicle, strength, waterproofness, chemical resistance, high temperature durability, etc. are required. In addition, it is necessary to prevent fogging of the lens due to temperature changes.

[0003] Patent Document 1 discloses a lens unit that secures an airtight state inside the lens barrel in order to prevent freezing of the front surface of the lens and fogging of the lens. In this lens unit, four lenses are arranged side by side along the optical axis direction inside the lens barrel. On the object side, a sealing property is achieved by arranging an O-ring between the lens closest to the object side and the inner peripheral surface of the lens barrel. Also, on the image side (image sensor side), a sealing property is achieved by attaching an optical filter to the lens barrel via an adhesive. In this way, the airtightness inside the lens barrel is ensured by the seal on the object side and the seal on the imaging side, and fogging of the lens is prevented.

Prior Art Documents

Patent Document

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, as described above, even if the airtight state inside the lens barrel is ensured, when the difference between the outside air temperature and the temperature inside the lens unit becomes large, the water vapor inside the lens unit condenses and dew forms on the lens surface. In particular, dew is likely to form on the back surface of the first lens (the lens located closest to the object side) and the second lens adjacent thereto, especially in the lens space between the first lens and the second lens.

[0006] Therefore, in order to remove the dew on the back surface of the first lens, it is conceivable to heat the first lens with a planar heater such as an FPC heater. The planar heater is formed in a donut plate shape and includes a heating portion that heats the first lens and a strip-shaped extending portion that extends from the heating portion and supplies electricity to the heating portion. The heating portion has a circuit layer formed of a circuit pattern formed by a copper foil and generates heat by the electrical resistance of the circuit pattern. In order to obtain a desired amount of heat generation, it is necessary to increase the electrical resistance value of the circuit pattern. In order to increase the electrical resistance value of the circuit pattern, the copper foil of the circuit pattern is thinned or the width of the copper foil is narrowed to increase the pattern length of the circuit pattern. However, when the diameter of the donut plate-shaped heating portion becomes small, it becomes impossible to increase the pattern length, and it is difficult to obtain a desired electrical resistance value, so it has been difficult to obtain a desired amount of heat generation. In addition, when the width of the copper foil forming the circuit pattern is narrowed, variations in the electrical resistance value are likely to occur, and disconnection is also likely to occur, which may reduce the electrical reliability of the circuit pattern.

[0007] The present invention has been made in view of the above circumstances, and an object thereof is to provide a lens unit and a camera module in which an FPC heater that heats a first lens located closest to the object side can obtain a desired calorific value and the reliability of the circuit pattern of the FPC heater is improved.

Means for Solving the Problems

[0008] In order to solve the above problems, the present invention provides a lens unit including a plurality of lenses arranged along an optical axis, a lens barrel that houses and holds these plurality of lenses, and an FPC heater capable of heating a first lens located closest to the object side. The FPC heater includes a heating portion that heats the first lens. The heating portion is characterized by having a plurality of circuit layers in which circuit patterns are formed by metal foils.

[0009] Here, although copper foil is preferably used as the metal foil for forming the circuit pattern, foils formed of metals other than copper, such as aluminum or SUS, may also be used.

[0010] In the present invention, since the heating portion of the FPC heater has a plurality of circuit layers in which circuit patterns are formed by metal foils, it is possible to multiply the pattern length of the circuit pattern. Even in an FPC heater having a small-sized heating portion, a desired electrical resistance value can be obtained, and thus a desired calorific value can be obtained. In addition, since it is not necessary to make the thickness of the metal foil for forming the circuit pattern thinner than necessary or narrow the width, variations in the electrical resistance value are less likely to occur, and disconnection is also less likely to occur. Therefore, the reliability of the circuit pattern is improved.

[0011] Further, in the configuration of the present invention, the circuit patterns formed in the plurality of circuit layers may be connected by through holes.

[0012] According to such a configuration, since the circuit patterns formed on the plurality of circuit layers are connected by through-holes, the pattern length of the circuit pattern can be easily increased.

[0013] Further, in the above configuration of the present invention, having two circuit layers, the heating part has a donut-shaped base film, the circuit layers may be provided on both the front and back surfaces of the base film, respectively.

[0014] According to such a configuration, since the circuit layers are provided on both the front and back surfaces of the base film, respectively, a heating part having two circuit layers can be easily obtained, and both circuit layers can be electrically insulated by the base film.

[0015] Further, in the above configuration of the present invention, the lens barrel has an inner peripheral surface formed in a polygonal shape with eight or more sides, and includes a housing and holding part for housing and holding an optical component located on the image side of the first lens. The FPC heater includes a strip-shaped extension part that extends from the heating part and supplies electricity to the heating part. An insertion groove extending in the axial direction of the lens barrel and having a groove width wider than the width of the extension part is provided in the housing and holding part. A lead-out hole for leading out the extension part inserted into the insertion groove to the outside may be provided in the lens barrel in communication with the insertion groove.

[0016] Here, in the lens barrel, a spacer may be provided between lenses adjacent in the optical axis direction, and the spacer is housed in the housing and holding part. For this reason, in the present invention, lenses, spacers, etc. are used as optical components. In addition, the "polygonal shape" includes a shape where the inner peripheral surface of the housing and holding portion is a regular polygonal shape with eight or more sides, a polygonal shape other than a regular polygonal shape with eight or more sides, and a combination of eight or more linear sides arranged at predetermined intervals in the circumferential direction and arcs arranged so as to connect adjacent sides in the circumferential direction. Furthermore, it also includes a shape having eight or more planes capable of supporting the outer periphery of the lens at points (point contact). By setting the inner peripheral surface of the housing and holding portion as a "regular polygonal shape", uniform holding (stress equal distribution) is possible and it is more effective for lens alignment.

[0017] According to such a configuration, an insertion groove having a groove width that extends in the axial direction of the lens barrel and is wider than the width of the extending portion is provided in the housing and holding portion that houses and holds optical components such as lenses and spacers. Therefore, by inserting the extending portion into the insertion groove, the extending portion can be easily routed inside the lens barrel. Furthermore, a lead-out hole for leading out the extending portion inserted into the insertion groove to the outside is provided in the lens barrel in communication with the insertion groove. Thus, the extending portion inserted into the insertion groove can be easily led out to the outside through the lead-out hole. Also, since the extending portion of the FPC heater does not interfere with the optical components, even if the extending portion is routed inside the lens barrel, the optical components will not be eccentric.

[0018] Moreover, the camera module according to the present invention is characterized by including the lens unit. According to such a configuration, the operational effects of the above-described lens unit can be obtained in the camera module.

Effects of the Invention

[0019] According to the present invention, the FPC heater that heats the first lens located closest to the object side can obtain a desired calorific value, and the reliability of the circuit pattern of the FPC heater is improved.

Brief Description of the Drawings

[0020]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Embodiments for Carrying Out the Invention

[0021] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the lens unit of the present embodiment described below is for a camera module such as an in-vehicle camera. For example, it is fixedly installed on the outer surface side of an automobile, and the wiring is drawn into the automobile and connected to a display or other devices. Also, in all the figures, hatching is omitted for the lenses and spacers.

[0022] FIG. 1 shows a lens unit 11 according to an embodiment of the present invention. As shown in the figure, the lens unit 11 of the present embodiment includes, for example, a cylindrical lens barrel (barrel) 12 made of resin, and a plurality of circular lenses in plan view arranged in the lens barrel 12. For example, from the object side (upper side in FIG. 1), there are five lenses including a first lens 13, a second lens 14, a third lens 15, a fourth lens 16, and a fifth lens 17, and three aperture members 22a, 22b, 22c. Further, on the bottom surface of the lens barrel 12, a groove extending radially is provided from the inner circumference of the bottom surface of the lens barrel 12 toward a portion not in contact with the lens 17. This groove is for the flow of air for airtight inspection.

[0023] Of the three diaphragm members 22a, 22b, and 22c, the first diaphragm member 22a from the object side is disposed between the second lens 14 and the third lens 15. The second diaphragm member 22b from the object side is disposed between the third lens 15 and the fourth lens 16. The third diaphragm member 22c from the object side is disposed between the fourth lens 16 and the fifth lens 17. The diaphragm member 22a is an "aperture diaphragm" that limits the amount of transmitted light and determines the F-value, which is an indicator of brightness. Also, the diaphragm members 22b and 22c are "light-shielding diaphragms" that block light rays that cause ghosting and light rays that cause aberrations. An in-vehicle camera including such a lens unit 11 includes the lens unit 11, a substrate having an image sensor (not shown), and an installation member (not shown) for installing the substrate in a vehicle such as an automobile.

[0024] The plurality of lenses 13, 14, 15, 16, and 17 accommodated in the lens barrel 12 are stacked and arranged with their respective optical axes aligned, and are arranged in a state where the lenses 13, 14, 15, 16, and 17 are arranged along a single optical axis O, constituting a group of lens groups L used for imaging. In this case, the first lens 13 located on the most object side that constitutes the lens group L is a spherical glass lens having a flat surface on the object side and a concave surface on the image side, and the second lens 14 is a spherical glass lens having convex curved surfaces on the object side and the image side, respectively. The other lenses 15, 16, and 17 are resin lenses, but are not limited thereto (for example, the first lens 13 and the second lens 14 may be resin lenses; when the first and second lenses 13 and 14 are made of resin, the first lens 13 and the second lens 14 may have, for example, a difference in linear expansion coefficient of 40×10 -6 / K(m) or more).

[0025] In addition, a spacer 30 is provided between the first lens 13 and the third lens 15 in the lens barrel 12, and there is an inter-lens space SL surrounded by the first lens 13, the third lens 15, the spacer 30, and the second lens 14. The first lens 13 and the spacer 30, and the spacer 30 and the third lens 15 may be adhered to each other so that the inside of the inter-lens space SL is sealed against the outside. The number of lenses, the number of spacers, the materials of the lenses, spacers, and lens barrel, etc. can be arbitrarily set according to the application, etc. Note that anti-reflection films, hydrophilic films, water-repellent films, etc. are provided on the surfaces of these lenses 13, 14, 15, 16, 17 as necessary.

[0026] The spacer 30 is formed in a cylindrical shape, and the second lens 14 is held at the inner lower end thereof. That is, the spacer 30 has a caulking portion 31 at the lower end edge on the inner diameter side, and this caulking portion 31 is thermally caulked radially inward so as to press the opposing surface 14a of the second lens 14 against the opposing surface 30b of the spacer 30 in the optical axis direction. In this way, since the opposing surface 14a of the second lens 14 is pressed against the opposing surface 30b by the caulking portion 31, the second lens 14 is held by the spacer 30.

[0027] Also, in this embodiment, an O-ring 26 as a sealing member is inserted between the first lens 13 located on the object side most and the lens barrel 12 to prevent water and dust from entering the lens group L inside the lens barrel 12. In this case, a stepped reduced-diameter portion 13e with a smaller diameter at the image side portion of the first lens 13 is provided on the outer peripheral surface 13d of the first lens 13, and the O-ring 26 is mounted on this reduced-diameter portion 13e. By radially compressing the O-ring 26 between the outer peripheral surface 13d of the first lens 13 and the inner peripheral surface 12a of the lens barrel 12, the object side end portion of the lens barrel 12 is in a sealed state. Note that the sealing member inserted between the first lens 13 and the lens barrel 12 is not limited to the O-ring 26, and any form may be used as long as it is an annular body that can seal between the first lens 13 and the lens barrel 12.

[0028] In addition, in a state where the lens group L is incorporated and held, the caulking portion 23 at the end on the object side (the upper end portion in FIG. 1) of the lens barrel 12 is thermally caulked radially inward, so that the first lens 13 located closest to the object side of the lens group L is fixed in the optical axis direction to the end on the object side of the lens barrel 12 by this caulking portion 23. In this case, in order to perform stable caulking, the portion of the glass lens 13 with which the caulking portion 23 is pressed is formed as a flat portion 13b that is obliquely cut in a planar shape.

[0029] In addition, the lens barrel 12 has an inner flange portion 24 having an opening with a diameter smaller than that of the fifth lens 17 at the end on the image side (the lower end portion in FIG. 1). The plurality of lenses 13, 14, 15, 16, 17 and the diaphragm members 22a, 22b, 22c that make up the lens group L are held and fixed in the optical axis direction by the inner flange portion 24 and the caulking portion 23 in the lens barrel 12.

[0030] The lens barrel 12 includes a housing and holding portion S that houses and holds the spacers 30 provided between the lenses 15, 16, 17 and the adjacent lenses 13, 15 in the optical axis direction. As shown in FIGS. 2 and 3, the inner peripheral surface of the housing and holding portion S is formed in a polygonal shape with eight or more sides. In this embodiment, the shape is a combination of 12 linear sides (chords) arranged at predetermined intervals in the circumferential direction and 12 arcs arranged so as to connect adjacent sides (chords) in the circumferential direction. In addition, the inner diameter of the housing and holding portion S gradually decreases from the object side toward the image side. Correspondingly, the outer diameters of the spacers 30, lenses 15, 16, 17 gradually decrease from the object side toward the image side. Basically, the outer diameters of the spacers 30, lenses 15, 16, 17 and the inner diameters of the portions of the housing and holding portion S of the lens barrel 12 that support the spacers 30 and the respective lenses 15, 16, 17 are substantially equal.

[0031] That is, taking the lens 15 as an example for explanation, as schematically shown in FIG. 5, the housing and holding portion S has 12 planar support surfaces SS because its inner peripheral surface is formed in a regular dodecagon shape, and these 12 support surfaces SS are adjacent to each other in the circumferential direction at equal angles. The central portion in the circumferential direction of each support surface SS is a support point SP that supports the outer peripheral surface of the lens 15, and there are 12 such support points SP. Therefore, the lens 15 is stably supported in the direction orthogonal to the optical axis by the 12 support points SP. As shown in FIG. 2, it has a shape formed by a combination of 12 linear sides (chords) arranged at predetermined intervals in the circumferential direction and 12 arcs arranged so as to connect adjacent sides (chords) in the circumferential direction. Hereinafter, it will be described as a regular dodecagon shape.

[0032] The housing and holding portion S that houses and holds the spacer 30 and the lenses 16 and 17 is also formed such that its inner peripheral surface is in a regular dodecagon shape. However, as going from the object side to the image side, the outer diameter (the distance between the support points SP arranged point-symmetrically about the optical axis) gradually decreases. Also, although the lenses 16 and 17 are each stably supported in the direction orthogonal to the optical axis by 12 support points SP, as will be described later, since the spacer 30 is provided with an insertion groove 55 in the housing and holding portion S, it is stably supported in the direction orthogonal to the optical axis by 10 support points SP.

[0033] Here, as shown in FIGS. 1 to 3, the housing and holding portion S is composed of a first housing and holding portion S1 that houses and holds the spacer 30, a second housing and holding portion S2 that houses the lens 15, a third housing and holding portion S3 that houses the lens 16, and a fourth housing and holding portion S4 that houses the lens 17, and the inner diameter gradually decreases from the first housing and holding portion S1 to the fourth housing and holding portion S4. And between the housing and holding portions adjacent to each other in the axial direction of the lens barrel 12, a stepped surface that projects radially inward is provided. Further, the accommodation and holding portion S shown in FIG. 2(a) is arranged with one vertex of the regular dodecagon facing the center in the width direction of the insertion groove 55 described later, while the accommodation and holding portion S shown in FIG. 2(b) is arranged with one vertex of the regular dodecagon facing the position rotated 15° in the circumferential direction from the center in the width direction of the insertion groove 55. In either case, the spacer 30 is supported by 10 support points SP.

[0034] Further, the accommodation and holding portion SU that houses the lens 13 closest to the object side has an inner peripheral surface formed in a circular shape, and the lens 13 is accommodated and held in the accommodation and holding portion SU. Further, the second lens 14 is formed to have a smaller diameter than the lenses 13, 15, 16, and 17, and is held and fixed by the spacer 30. Note that an outer flange portion 25 used when the lens barrel 12 is installed in an in-vehicle camera is provided in a flange shape on the outer peripheral surface of the lens barrel 12.

[0035] FIG. 6 is a schematic cross-sectional view of the camera module 300 of the present embodiment having the lens unit 11 shown in FIG. 1. As shown in the figure, the camera module 300 includes a lens unit 11 to which a filter 105 is attached.

[0036] The camera module 300 includes an upper case (not shown) which is an exterior component, and a mount (pedestal) 302 that holds the lens unit 11. The camera module 300 also includes a seal member 303 and a package sensor (imaging element) 304.

[0037] The upper case is a member that exposes the end portion of the lens unit 11 on the object side and covers the other portions. The mount 302 is disposed inside the upper case and has a female screw 302a that engages with the male screw 11a of the lens unit 11. The package sensor 304 is disposed inside the mount 302 and at a position where it receives the image of an object formed by the lens unit 11. The package sensor 304 includes a CCD, a CMOS, or the like, and converts the light that is condensed and reaches through the lens unit 11 into an electrical signal. The converted electrical signal is converted into analog data or digital data that is a component of the image data captured by the camera.

[0038] As shown in FIGS. 1 and 6, the lens unit 11 and the camera module 300 configured as described above include an FPC heater 50 capable of heating the lens 13 located closest to the object side. As shown in FIG. 7, the FPC heater 50 is formed of a flexible printed circuit board and includes a heating portion 51 that heats the first lens 13 and an extending portion 52 that extends from the heating portion 51 and supplies electricity to the heating portion 51. Note that FIG. 7(a) is a top view of the FPC heater 50, and FIG. 7(b) is a bottom view of the FPC heater 50.

[0039] The heating portion 51 is formed in a donut plate shape, and the outer diameter is substantially equal to the outer diameter of the image-side end face of the first lens 13, and the inner diameter is substantially equal to the inner diameter of the image-side end face of the first lens 13. As shown in FIG. 8, the heating portion 51 has two circuit layers 72 in which a circuit pattern 71 (see FIG. 7) formed of a copper foil 70 is formed. Note that the circuit pattern 71 may be formed of an aluminum foil or a SUS foil instead of the copper foil 70. The heating portion 51 also has a donut plate-shaped base film 75 at the central portion in the thickness direction. The base film 75 is formed of a polyimide film. The polyimide film has very high strength, excellent heat resistance, and excellent electrical insulation properties. Circuit layers 72 are provided on both the front and back surfaces of this base film 75. That is, adhesive layers 73 are provided on both the front and back surfaces of the base film 75, and circuit layers 72, 72 are provided on the surfaces of the adhesive layers 73, 73. The adhesive layer 73 and the adhesive layer 77 described later are formed of a thermosetting resin such as epoxy, silicone resin, or urea resin.

[0040] The base film 75 and the adhesive layers 73, 73 constitute an insulating layer, and through holes 76 are provided so as to penetrate the insulating layer in the thickness direction. The inner surface of the through hole 76 is provided with a copper plating film 76a, and the circuit patterns 71, 71 of the circuit layers 72, 72 are electrically connected by the copper plating film 76a. Two through holes 76 are provided, and the circuit patterns 71, 71 are connected at the ends on the heating part 51 side of the extending part 52. Also, adhesive layers 77, 77 are provided on the surfaces of the circuit layers 72, 72, and cover films 78, 78 are provided on the surfaces of the adhesive layers 77, 77. The cover film 78 is formed of a polyimide film in the same manner as the base film 75.

[0041] As shown in FIG. 7, the circuit pattern 71 is formed by symmetrically forming a circuit part formed in a semicircular shape by folding a thin linear copper foil 70 from the outer peripheral side to the inner peripheral side so as to form a semi-circular arc on a donut-shaped base film 75, and this circuit part is configured to generate heat. The circuit pattern 71 may be formed by well-known etching processing, or may be formed by an inkjet printer using micropiezo technology.

[0042] The extending part 52 extends linearly radially outward from the heating part 51, and is formed by arranging two strip-shaped copper foils 52a, 52b in parallel on the surface of a strip-shaped base film 75a. One of the copper foils 52a, 52b is connected to the anode of the power supply, and the other is connected to the cathode. Note that the base film 75a is integrally formed with the base film 75 of the heating part 51. Also, the layer structure of the extending portion 52 is the same as that of the heating portion 51. Therefore, a cover film is provided on the surfaces of the copper foils 52a and 52b via an adhesive layer. Also, at the base end portion of the extending portion 52, the copper foils 52a and 52b are exposed, and this exposed portion is connected to the power supply.

[0043] As shown in FIG. 7(a), the copper foil 52a is connected to one end portion of the circuit pattern 71 on the surface side on the surface of the extending portion 52, and a connection portion 52c formed of copper foil is connected to the other end portion of the circuit pattern 71. As shown in FIG. 7(b), on the back surface of the extending portion 52, a connection portion 52d is formed of copper foil so as to face the connection portion 52c on the surface side in the thickness direction, and the connection portion 52c is connected to the connection portion 52d. The connection portion 52c and the connection portion 52d are connected by the through hole 76. This connection portion 52d is connected to one end portion of the circuit pattern 71 on the back surface side, and a connection portion 52e formed of copper foil is connected to the other end portion of the circuit pattern 71. As shown in FIG. 7(a), on the surface of the extending portion 52, a connection portion 52f is formed of copper foil so as to face the connection portion 52e on the back surface side in the thickness direction, and the connection portion 52f is connected to the connection portion 52e. The connection portion 52e and the connection portion 52f are connected by the through hole 76. Thereby, the circuit pattern 71 on the surface side and the circuit pattern 71 on the back surface side of the extending portion 52 are connected. Therefore, by connecting one of the copper foils 52a and 52b to the anode of the power supply and the other to the cathode, electricity is supplied to the circuit patterns 71 and 71 on both the front and back surfaces, and the circuit patterns 71 and 71 generate heat.

[0044] As shown in FIGS. 2 and 3, an insertion groove 55 extending in the axial direction of the lens barrel 12 is provided in the housing and holding portion S. This insertion groove 55 has a groove width wider than the width of the extending portion 52 of the FPC heater 50 and a groove depth deeper than the thickness of the extending portion 52. Further, the insertion groove 55 extends from the object side end of the first housing and holding portion S1 to a position slightly on the object side from the image side end of the first housing and holding portion S1. The heating part 51 of the FPC heater 50 is adhered to the end face 13a on the image side of the lens 13 with an adhesive. As the adhesive, a thermosetting adhesive with excellent thermal conductivity is used. For example, epoxy resin, epoxy resin containing conductive filler, etc. are preferably used. The thermal conductivity of the adhesive is preferably 0.2 to 2.0 W / m·K. The adhesive is evenly applied over the upper surface of the heating part 51 of the FPC heater 50 (the surface facing the first lens 13 side) and / or the end face 13a on the image side of the first lens 13, and then these upper surface and end face 13a are adhered. Note that it is preferable to apply the adhesive evenly, but it may also be applied and adhered at a plurality of predetermined positions. The extension part 52 is directed toward the insertion groove 55 and is inserted into the insertion groove 55.

[0045] Also, on the peripheral wall of the lens barrel 12, a lead-out hole 56 is provided in communication with the insertion groove 55. The lead-out hole 56 is a rectangular hole, the hole width is equal to the groove width of the insertion groove 55, and the lead-out hole 56 is formed to penetrate the peripheral wall of the lens barrel 12. The outlet of the lead-out hole 56 is arranged on the peripheral wall of the lens barrel 12 above the outer flange part 25. Such a lead-out hole 56 is for leading out the extension part 52 of the FPC heater 50 inserted into the insertion groove 55 to the outside of the lens barrel 12. The extension part 52 inserted into the insertion groove 55 is bent radially outward at a substantially right angle at the entrance of the lead-out hole 56, and then is inserted into the lead-out hole 56 and led out to the outside. In addition, the insertion groove 55 may be extended to the upper surface of the inner flange part 24, and a lead-out hole may be provided to penetrate the inner flange part 24 in the thickness direction thereof.

[0046] When adhering the heating part 51 of the FPC heater 50 to the end face 13a on the image side of the first lens 13 with an adhesive and leading out the extension part 52 of the FPC heater 50 to the outside of the lens barrel 12, it is performed as follows. First, from the opening on the object side (the upper end side in FIG. 1) into the lens barrel 12, the lens 17, the aperture member 22c, the lens 16, the aperture member 22b, the lens 15, and the aperture member 22a are sequentially inserted. On one hand, the spacer 30 and the lens 14 are pre-assembled outside the lens barrel 12 to form an assembly. Also, outside the lens barrel 12, the upper surface of the heating part 51 of the FPC heater 50 is adhered to the end face 13a of the first lens 13 with an adhesive.

[0047] Next, after inserting the said assembly into the lens barrel 12, the first lens 13 to which the heating part 51 of the FPC heater 50 is adhered is inserted into the lens barrel 12. At this time, the first lens 13 is positioned in the circumferential direction so that the extending part 52 of the FPC heater 50 faces the insertion groove 55 side, and the extending part 52 is inserted into the said insertion groove 55. When the extending part 52 is inserted into the insertion groove 55 and its tip reaches the lead-out hole 56, the extending part 52 is bent radially outward and inserted outward along the lead-out hole 56, and is led out to the outside of the lens barrel 12. Then, while pulling the led-out extending part 52, the first lens 13 to which the heating part 51 of the FPC heater 50 is adhered is inserted into the lens barrel 12. Finally, by thermally caulking the caulking part 23 radially inward, the lens group L is fixed within the lens barrel 12. Also, when inserting the first lens 13 into the lens barrel 12, an O-ring 26 is attached to the first lens 13 in advance.

[0048] Note that, not limited to this, it may also be as follows. That is, before inserting the said assembly into the lens barrel 12, with the first lens 13 to which the heating part 51 of the FPC heater 50 is adhered taken out of the lens barrel 12, the extending part 52 is inserted into the insertion groove 55, further inserted into the lead-out hole 56, and led out to the outside of the lens barrel 12. Next, after inserting the said assembly into the lens barrel 12, the first lens 13 taken out to the outside is inserted into the lens barrel 12. Finally, by thermally caulking the caulking part 23 radially inward, the lens group L is fixed within the lens barrel 12.

[0049] Also, in this embodiment, as shown in FIG. 2, the angle θ formed by the line connecting both ends in the width direction of the insertion groove 55 and the center О of the accommodation and holding part S (the first accommodation and holding part S1) is within 60°. As shown in Fig. 2(a), the inner peripheral surface of the first accommodation and holding part S1 is formed in a regular polygonal shape with 12 or more sides, and a part of the inner peripheral surface is cut out in a rectangular groove shape, so that out of the 12 support surfaces SS, two support surfaces SS are cut out. Therefore, the spacer 30 is supported by 10 support points SP. For this reason, even if the insertion groove 55 is formed, the spacer 30 can be stably supported. Also, as shown in Fig. 2(b), the inner peripheral surface of the first accommodation and holding part S1 is formed in a regular polygonal shape with 12 or more sides, and a part of the inner peripheral surface is cut out in a rectangular groove shape, so that out of the 12 support surfaces SS, one support surface SS and less than half of two support surfaces SS are cut out. Therefore, the spacer 30 is supported by 10 support points SP. For this reason, even if the insertion groove 55 is formed, the spacer 30 can be stably supported.

[0050] As shown in Fig. 9, the outer diameter portions of the lenses 15 to 17 and the spacer 30 are formed by a cylindrical surface, and a flat surface 30a is formed on a part of the cylindrical surface, resulting in a D-cut shape. It is preferable to arrange such a D-cut portion of the D-cut shape so as to face the insertion groove 55. The flat surface 30a is a part that becomes a gate when the lenses 15 to 17 and the spacer 30 are molded, and the flat surface 30a is a part that does not originally come into contact with the support surface SS of the first accommodation and holding part S1. Therefore, as shown in Fig. 10, by arranging the flat surface 30a in the insertion groove 55, the spacer 30 can be supported by 10 support points SP. There is a sufficient gap between the flat surface 30a arranged in the insertion groove 55 and the groove bottom surface of the insertion groove 55 through which the extension 52 of the FPC heater 50 can be inserted.

[0051] Also, in the present embodiment, as shown in Fig. 2, the groove width W of the insertion groove 55 is within 3.5 mm. As described above, when the groove width of the insertion groove 55 is set so that the angle θ is within 60°, the larger the outer diameter of the spacer 30, the larger the groove width of the insertion groove 55. Therefore, in order to suppress it from becoming excessive, the groove width W of the insertion groove 55 is defined to be within 3.5 mm.

[0052] As described above, according to the present embodiment, since the heating portion 51 of the FPC heater 50 has two circuit layers 72 in which the circuit pattern 71 is formed by the copper foil 70, it is possible to double the pattern length of the circuit pattern 71. Even in the FPC heater 50 having a small-sized heating portion 51, a desired electrical resistance value can be obtained, and thus a desired calorific value can be obtained. In addition, since it is not necessary to make the thickness of the copper foil 70 forming the circuit pattern 71 thinner than necessary or to narrow the width, variations in the electrical resistance value are less likely to occur, and disconnection is also less likely to occur. Therefore, the reliability of the circuit pattern 71 is improved. In addition, since the circuit patterns 71, 71 of the two circuit layers 72, 72 are connected by the through holes 76, the pattern length of the circuit pattern can be easily lengthened. Furthermore, since the circuit layer 72 is provided on both the front and back surfaces of the base film 75, it is possible to easily obtain the heating portion 51 having the two circuit layers 72, 72, and the two circuit layers 72, 72 can be electrically insulated by the base film 75.

[0053] In addition, since the heating portion 51 of the FPC heater (planar heater) 50 is adhered to the end surface 13a on the image side of the first lens 13 by an adhesive, even if the lens unit 11 changes in temperature due to the environment, especially when it becomes high temperature, and a gap is generated between the lens barrel 12 and the spacer 30 housed and held therein, no gap is generated between the first lens 13 and the heating portion 51 of the FPC heater 50, so no air intervenes. Thus, since no air intervenes, the thermal conductivity does not decrease, and therefore, the first lens 13 can be stably and surely heated by the heating portion 51. In addition, since the heating portion 51 of the FPC heater 50 is adhered to the end surface 13a on the image side of the first lens 13 by a thermosetting adhesive, when a blackened portion for ghost prevention is provided on the end surface 13a on the image side of the first lens 13, the heating portion 51 cannot be adhered to the end surface 13a on the image side of the first lens 13 with a UV curable adhesive, but can be surely adhered with a thermosetting adhesive.

[0054] In addition, the first accommodation and holding portion S1 that accommodates and holds the spacer 30 is provided with an insertion groove 55 that extends in the axial direction of the lens barrel 12 and has a groove width wider than the width of the extending portion 52 of the FPC heater 50. Therefore, by inserting the extending portion 52 into the insertion groove 55, the extending portion 52 can be easily routed inside the lens barrel. Further, a lead-out hole 56 for leading out the extending portion 52 inserted into the insertion groove 55 to the outside is provided in communication with the insertion groove 55 on the peripheral wall of the lens barrel 12. Therefore, the extending portion 52 inserted into the insertion groove 55 can be easily led out to the outside through the lead-out hole 56. In addition, since the extending portion 52 of the FCC heater 50 does not interfere with the spacer 30 or the lenses 15, 16, 17, the spacer 30 or the lenses 15, 16, 17 will not be eccentric even if the extending portion 52 is routed inside the lens barrel 12.

[0055] In addition, since the lead-out hole 56 is provided in the peripheral wall of the lens barrel 12, the extending portion 52 of the FPC heater 50 can be easily led out from the peripheral wall of the lens barrel 12. Furthermore, since the angle formed by the line connecting both ends of the insertion groove 55 in the extending direction and the center of the first accommodation and holding portion S1 is within 60°, the outer peripheral surface of the spacer 30 can be held at 10 support points SP on the first accommodation and holding portion S1 whose inner peripheral surface is formed in a regular dodecagon. Therefore, the spacer 30 can be stably held. In addition, since the groove width of the insertion groove 55 is within 3.5 mm, the extending portion 52 of the FPC heater 50 with a width within 3.5 mm can be easily inserted into the insertion groove 55.

[0056] In this embodiment, the spacer 30, the lenses 15, 16, 17 are accommodated and held in the accommodation and holding portion S. However, only a plurality of lenses may be accommodated and held in the accommodation and holding portion S. That is, the spacer 30 may not be provided. In addition, in this embodiment, the inner peripheral surface of the accommodation and holding portion SU that accommodates and holds the lens 13 located closest to the object side is formed in a circular shape. However, the inner peripheral surface of the accommodation and holding portion SU may be formed in a polygonal shape with eight or more sides. Furthermore, in this embodiment, the circuit layer 72 has two layers, but it may have a plurality of layers of three or more layers.

Explanation of Reference Numerals

[0057] 11 Lens unit 12 Lens barrel 13 First lens 14, 15, 16, 17 Lenses 30 Spacer 50 FPC heater 51 Heating part 52 Extension part 55 Insertion groove 56 Lead-out hole 70 Copper foil (metal foil) 71 Circuit pattern 72 Circuit layer 75 Base film 76 Through hole L Lens group O Optical axis

Claims

1. In a lens unit including a plurality of lenses arranged along an optical axis, a lens barrel that houses and holds these plurality of lenses, and an FPC heater capable of heating a first lens located on the most object side, the FPC heater includes a heating portion that is located on an image-side end surface of the first lens and heats the first lens, and a strip-shaped extending portion that extends from the heating portion to a radially outer portion and extends axially along an inner surface of the lens barrel and supplies electricity to the heating portion, the heating portion has a plurality of circuit layers in which circuit patterns are formed by metal foils, the circuit patterns formed in the plurality of circuit layers are connected by a plurality of through holes, the plurality of through holes are provided at an end portion of the extending portion on the heating portion side, and end portions of the circuit patterns are connected to each other at this end portion. A lens unit characterized by this.

2. having two circuit layers, the heating portion has a donut-shaped base film, The lens unit according to claim 1, wherein the circuit layers are respectively provided on both the front and back surfaces of the base film.

3. the lens barrel has an inner peripheral surface formed in a polygonal shape with eight or more sides, and includes a housing and holding portion that houses and holds optical components located on the image side of the first lens, an insertion groove extending in the axial direction of the lens barrel and having a groove width wider than the width of the extending portion of the FPC heater is provided in the housing and holding portion, The lens unit according to claim 1 or 2, wherein a lead-out hole for leading out the extending portion inserted into the insertion groove to the outside is provided in the lens barrel in communication with the insertion groove.

4. A camera module comprising the lens unit according to any one of claims 1 to 3.

Images