Lens unit

Abstract

To provide a lens unit capable of easily performing a change in specifications even without changing an overall configuration of an electric conductor layer when a conducting wire provided on a flexible print board is used as a heater part.SOLUTION: A lens unit 1 comprises: a lens holder 2 for holding a plurality of lenses including a first lens L1 and a second lens L2; and a flexible print board 3 provided with an electric conductor layer 9. The flexible print board 3 includes: an annular part 31 having an annular shape and overlapping an image-side flange surface 13 of the first lens L1; and an extension part 32 extending from the annular part 31 to an outside in a radial direction. The electric conductor layer 9 has: the heater part 6 extending in a circular arc shape in a circumferential direction along the annular part 31; and a power supply line 8 extending from the heater part 6 along an extension part 32. An electric resistance of the heater part 6 is greater than an electric resistance of the power supply line 8.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a lens unit in which a plurality of lenses are arranged on an optical axis.

[0002] Patent Document 1 describes a lens unit used in an optical device. The lens unit in this document includes a plurality of lenses and a lens holder that holds the plurality of lenses. The lens unit also includes a flexible printed circuit board that includes a heater unit for preventing condensation from forming inside the lens holder when the lens unit is used outdoors.

[0003] The flexible printed circuit board is disposed between a first lens disposed closest to the object side and a second lens disposed closer to the image side than the first lens. The flexible printed circuit board includes an annular plate-shaped portion that contacts the first lens and an extension portion that extends radially outward from the plate-shaped portion. The conductive layer that constitutes the heater portion includes a circumferential portion disposed on the plate-shaped portion, a first extension portion that extends from one end of the circumferential portion along the extension portion, and a second extension portion that extends from the other end of the circumferential portion along the extension portion, and the circumferential portion generates heat by supplying power to the circumferential portion via the first extension portion and the second extension portion. This causes the temperature around the first lens to rise. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-168509 A Summary of the Invention [Problem to be solved by the invention]

[0005] The voltage supplied to the heater section and the amount of heat required from the heater section vary depending on the optical device the lens unit is used in. Therefore, with a flexible printed circuit board, it is necessary to design the structure of the entire conductive layer, including the circumferential section, the first extension section, and the second extension section, according to the required specifications, which causes a problem of increased costs.

[0006] In view of the above problems, an object of the present invention is to provide a lens unit whose specifications can be easily changed without changing the overall configuration of the conductor layer when a conductor provided on a flexible printed circuit board is used as a heater section. [Means for solving the problem]

[0007] In order to solve the above problem, the lens unit of the present invention has a first lens, a second lens arranged on the image side of the first lens, a lens holder that holds a plurality of lenses including the first lens and the second lens, and a flexible printed circuit board provided with a conductive layer, wherein the first lens has an image side lens surface and an image side flange surface surrounding the image side lens surface, the flexible printed circuit board has an annular portion overlapping the image side flange surface and an extension portion extending radially outward from the annular portion, the conductive layer includes a heater portion extending in an arc shape in the circumferential direction along the annular portion, and a power supply wiring extending from the heater portion along the extension portion, and the electrical resistance of the heater portion is greater than the electrical resistance of the power supply wiring.

[0008] In the present invention, the electrical resistance of the heater section is greater than the electrical resistance of the power supply wiring. Therefore, if the specifications such as the voltage applied to the power supply wiring are changed, the value of the current flowing through the entire conductor layer including the heater section and the power supply wiring can be easily changed by adjusting the resistance of the heater section, which has a large electrical resistance. Therefore, the amount of heat generated by the heater section can be easily changed. Also, since the part with a large electrical resistance is the heater section, the amount of heat generated by the heater section can be easily adjusted. Therefore, the specifications of the heater can be easily changed without changing the overall configuration of the conductive layer.

[0009] In the present invention, it is preferable that the thickness of the heater section is thinner than the thickness of the power supply wiring. With this configuration, it is easy to make the electrical resistance of the heater section greater than the electrical resistance of the power supply wiring by making the thickness of the heater section thinner than the thickness of the power supply wiring. Therefore, it is easy to adjust the amount of heat generated by the heater section by adjusting the thickness of the heater section.

[0010] In the present invention, it is preferable that the heater portion includes a first portion having a thickness thinner than the power supply wiring and a second portion having a thickness equal to that of the power supply wiring, which makes it easy to adjust the electrical resistance of the heater portion.

[0011] In the present invention, it is preferable that the first portion and the second portion are arranged in a circumferential direction, and the circumferential length of the first portion arranged at the farthest position from the connection portion electrically connected to the power supply wiring among the plurality of first portions is longer than the circumferential length of the other first portions. Here, the heater portion tends to generate less heat the farther away it is from the connection portion electrically connected to the power supply wiring portion. Therefore, by configuring in this way, it is possible to increase the amount of heat generated in the first portion arranged at the farthest position from the connection portion electrically connected to the power supply wiring. This allows the heater portion to be heated uniformly, so that condensation generated on the first lens can be removed more efficiently.

[0012] In the present invention, it is preferable that the thickness of the heater portion becomes thinner as it moves away from the connection portion electrically connected to the power supply wiring in the circumferential direction. With this configuration, it is possible to increase the electrical resistance of the heater portion as it moves away from the connection portion electrically connected to the power supply wiring in the circumferential direction. Therefore, by adjusting the thickness of the heater portion, it is easy to adjust the amount of heat generated by the heater portion, and the heater portion can be heated uniformly, so that condensation generated on the first lens can be removed more efficiently.

[0013] In the present invention, it is preferable that the heater section has a plurality of holes. With this configuration, it is easy to make the electrical resistance of the heater section larger than the electrical resistance of the power supply wiring simply by providing a plurality of holes in the heater section. Therefore, it is easy to adjust the amount of heat generated by the heater section.

[0014] In the present invention, it is preferable that the number of holes increases with increasing distance in the circumferential direction from the connection part electrically connected to the power supply wiring. With this configuration, the electrical resistance of the heater part can be increased with increasing distance in the circumferential direction from the connection part electrically connected to the power supply wiring. Therefore, the heater part can be heated uniformly, and condensation formed on the first lens can be removed more efficiently.

[0015] In the present invention, the heater portion may be formed of a heater wire folded back a number of times in the circumferential direction. Effect of the Invention

[0016] In the present invention, the electrical resistance of the heater section is greater than the electrical resistance of the power supply wiring. Therefore, if the specifications, such as the voltage applied to the power supply wiring, are changed, the resistance of the heater section, which has a large electrical resistance, can be adjusted to easily change the value of the current flowing through the entire conductor layer, including the heater section and the power supply wiring. This makes it possible to easily change the amount of heat generated by the heater section. Furthermore, since the part with a large electrical resistance is the heater section, it is easy to adjust the amount of heat generated by the heater section. Therefore, the specifications of the heater can be easily changed without changing the overall configuration of the conductor layer. This can be done. [Brief description of the drawings]

[0017] [Figure 1] 1 is a cross-sectional view of a lens unit according to an embodiment of the present invention. [Diagram 2] FIG. 2 is an exploded sectional perspective view of the lens unit of FIG. [Diagram 3] FIG. 1 is a plan view of a flexible printed circuit board according to a first embodiment. [Figure 4] FIG. 11 is a plan view of a flexible printed circuit board according to a second embodiment. [Diagram 5] FIG. 13 is a plan view of a flexible printed circuit board according to a third embodiment. [Figure 6] FIG. 13 is a plan view of a flexible printed circuit board according to a fourth embodiment. [Figure 7] FIG. 13 is a plan view of a flexible printed circuit board according to a fifth embodiment. [Figure 8] FIG. 13 is a plan view of a flexible printed circuit board according to a sixth embodiment. [Figure 9] 13 is a plan view of a flexible printed circuit board relating to a heater portion of a modified example. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a lens unit to which the present invention is applied will be described with reference to the drawings.

[0019] FIG. 1 is a cross-sectional view of a lens unit according to an embodiment of the present invention. FIG. 2 is a cross-sectional perspective view of the lens unit of FIG. 1. In FIG. 1, L is the optical axis of the lens unit 1. La is one side in the optical axis direction, which is the object side of the lens unit 1. Lb is the other side in the optical axis direction, which is the image side of the lens unit 1. As shown in FIG. 1 and FIG. 2, the lens unit 1 includes a plurality of lenses, a lens holder 2 that holds the plurality of lenses, and a flexible printed circuit board 3 that includes a heater portion 6 made of a conductive layer.

[0020] (multiple lenses) The lenses are provided with 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, in that order from the object side La to the image side Lb. Therefore, the first lens L1 is located closest to the object side La, and the sixth lens L6 is located closest to the image side Lb. 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.

[0021] The first lens L1 and the fourth lens L4 are glass lenses. The first lens L1 has an object-side lens surface 11 that is convex toward the object side La, an image-side lens surface 12 that is concave toward the object side La, an image-side flange surface 13 that surrounds the outer periphery of the image-side lens surface 12, and an annular step portion 14 that is recessed toward 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 on the annular step portion 14.

[0022] The fourth lens L4 is arranged inside the lens holder 2 while being fixed to a frame-shaped holder 5. 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 form a cemented lens L9. Note that the number and configuration of lenses held by the lens holder 2 are not limited to the above number and configuration.

[0023] (Lens holder) The lens holder 2 is made of resin. The lens holder 2 includes a first housing portion 21 that holds the first lens L1, a second housing portion 22 that is disposed on the image side Lb of the first housing portion 21, and a lens case 23 that surrounds the outer circumferential side of the second housing portion 22. The lens case 23 extends from the outer circumferential end of the first housing portion 21 to the image side Lb. The second housing portion 22 holds the second lens L2, the third lens L3, the fourth lens L4, and the cemented lens L9.

[0024] In the lens holder 2, a first lens L1 is disposed based on the inner peripheral surface of the first housing portion 21. Further, the second lens L2, the third lens L3, the fourth lens L4, and the cemented lens L9 are disposed with the inner circumferential surface of the second housing portion 22 as a reference.

[0025] The first housing portion 21 includes an annular bottom portion 24 facing the La direction, and a peripheral wall portion 25 surrounding the first lens L1. The first lens L1 is housed in the first housing portion 21, and is fixed by a crimping portion 27 provided at the tip of the peripheral wall portion 25. The gap between the first lens L1 and the first housing portion 21 is sealed by an O-ring 7.

[0026] The second housing portion 22 includes a tube portion 28 connected to the bottom portion 24 of the first housing portion 21, and a bottom portion 29 provided at an end portion on the image side Lb of the tube portion 28 extending in the direction of the optical axis L. The second lens L2, the third lens L3, the fourth lens L4, and the cemented lens L9 are positioned in the direction of the optical axis L based on a lens seat surface 29a formed on the bottom portion 29 of the second housing portion 22.

[0027] The cemented lens L9 is positioned in the optical axis L direction by the outer peripheral portion of the fifth lens L5 abutting against the lens seating surface 29a. The fourth lens L4 located on the object side La of the cemented lens L9 is held by the holder 5, and the holder 5 abuts against the outer peripheral portion of the fifth lens L5 in the optical axis L direction. 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 holder 5 in the optical axis L direction via the diaphragm L8. Furthermore, 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 seating surface 29a as a reference. The second lens L2 is fixed by crimping by the crimping portion 28a provided at the end of the object side La of the tube portion 28.

[0028] The lens holder 2 also has a through hole 26 that penetrates the bottom 24 of the first housing portion 21 in the optical axis L direction. The through hole 26 communicates with a gap between the tube portion 28 of the second housing portion 22 and the lens case 23. As will be described later, the flexible printed circuit board 3 is inserted into the through hole 26 and drawn out to the image side Lb of the lens holder 2 through the gap between the inner circumferential surface of the lens case 23 and the outer circumferential surface of the tube portion 28. The number, size and position of the through holes 26 are determined according to the shape of the flexible printed circuit board 3.

[0029] (Flexible Printed Circuit Board) (First embodiment) Fig. 3 is a plan view of the flexible printed circuit board 3 according to the first embodiment. As shown in Fig. 1, the flexible printed circuit board 3 is disposed between the first lens L1 and the second lens L2. As shown in Fig. 3, the flexible printed circuit board 3 is provided with a heater section 6 and a power supply wiring 8 that is electrically connected to the heater section 6 and supplies power to the heater section 6.

[0030] 2 and 3, the flexible printed circuit board 3 includes an annular portion 31 that overlaps the image side flange surface 13 on the image side Lb, and an extension portion 32 that extends linearly radially outward from the annular portion 31. The annular portion 31 is in contact with the image side flange surface 13. An opening hole 33 is formed in the center of the annular portion 31 so that the lens surface of the second lens L2 is exposed. The annular portion 31 is disposed in a state where it is sandwiched between the bottom portion 24 of the first housing portion 21 and the image side flange surface 13 of the first lens L1.

[0031] 2, the extension portion 32 is bent at a right angle to the annular portion 31, and inserted into the through hole 26. The extension portion 32 inserted into the through hole 26 passes through a gap between the inner peripheral surface of the lens case 23 and the outer peripheral surface of the tube portion 28, and is drawn out to the image side Lb of the lens holder 2.

[0032] The flexible printed circuit board 3 is provided with a conductive layer 9. The conductive layer 9 is The heater unit 6 includes a first power supply wiring 8 and a power supply wiring 8. The heater unit 6 is disposed in the annular portion 31. The heater unit 6 extends in an arc shape in the circumferential direction along the periphery of the opening hole 33. The power supply wiring 8 is disposed in the extension portion 32. The power supply wiring 8 includes a first power supply wiring 81 connected to one end of the heater unit 6 and a second power supply wiring 82 connected to the other end of the heater unit 6. One of the first power supply wiring 81 and the second power supply wiring 82 is connected to a positive electrode, and the other of the first power supply wiring 81 and the second power supply wiring 82 is connected to a negative electrode.

[0033] The flexible printed circuit board 3 includes a flexible substrate 30 made of a resin film such as polyimide, and a heater section 6 and a power supply wiring 8 are formed on the surface of the flexible substrate 30 by a conductor layer 9 such as Cu. An overcoat layer that covers the heater section 6 and the power supply wiring 8 is formed on the surface of the flexible substrate 30. The annular section 31 of the flexible printed circuit board 3 has a uniform thickness. In this embodiment, the line width of the heater section 6 is wider than the line widths of the first power supply wiring 81 and the second power supply wiring 82 when viewed from the optical axis L direction.

[0034] In this embodiment, the thickness of the heater section 6 in the optical axis L direction is thinner than the thickness of the power supply wiring 8. Therefore, the electrical resistance of the heater section 6 is greater than the electrical resistance of the power supply wiring 8. Here, the thickness of the heater section 6 is adjusted when the flexible printed circuit board 3 is manufactured. Specifically, the relationship between the thickness and electrical resistance of the heater section 6, the electrical resistance of the heater section 6, the relationship between the voltage supplied to the heater section 6 and the heat generation amount of the heater section 6, etc. are obtained in advance, and the thickness of the heater section 6 is determined from the power supplied to the heater section 6 from the optical device in which the lens unit 1 is used and the desired heat generation amount of the heater section 6. Then, the conductive layer 9 is disposed on the flexible substrate 30 of the annular section 31 so that the heater section 6 has the determined thickness when the flexible printed circuit board 3 is manufactured.

[0035] The flexible printed circuit board 3 is electrically connected to a higher-level device, and when power is supplied from the higher-level device board to the first power supply wiring 81 and the second power supply wiring 82, the heater section 6 generates heat. When the heater section 6 generates heat, the first lens L1 in contact with the annular section 31 is heated. Therefore, when the lens unit is used in a low outside temperature, the first lens L1 is heated by the heater section 6, so that condensation on the image-side lens surface 12 of the first lens L1 can be suppressed.

[0036] (Effects of this embodiment) In this embodiment, the electrical resistance of the heater section 6 is greater than the electrical resistance of the power supply wiring 8. Therefore, when the specifications such as the voltage applied to the power supply wiring 8 are changed, the value of the current flowing through the entire conductive layer 9 including the heater section 6 and the power supply wiring 8 can be easily changed by adjusting the resistance of the heater section 6, which has a large electrical resistance. Therefore, the amount of heat generated by the heater section 6 can be easily changed. In addition, since the part with a large electrical resistance is the heater section 6, the amount of heat generated by the heater section 6 can be easily adjusted. Therefore, the specifications of the heater can be easily changed without changing the entire configuration of the conductive layer 9.

[0037] Second embodiment Next, a flexible printed circuit board 3 according to a second embodiment will be described. Fig. 4 is a plan view of the flexible printed circuit board 3 according to the second embodiment. Note that the same components as those in the first embodiment are given the same reference numerals, and the description thereof may be omitted.

[0038] 4, the flexible printed circuit board 3 includes an annular portion 31 that is in contact with the image side flange surface 13, and an extension portion 32 that extends radially outward from the annular portion 31. An opening hole 33 is formed in the center of the annular portion 31 so that the lens surface of the second lens L2 is exposed. The annular portion 31 is disposed in a state where it is sandwiched between the bottom portion 24 of the first housing portion 21 and the image side flange surface 13 of the first lens L1.

[0039] The heater portion 6 is disposed in the annular portion 31. The heater portion 6 extends in an arc shape in the circumferential direction along the periphery of the opening hole 33. The power supply wiring 8 is disposed in the extension portion 32. The power supply wiring 8 includes a first power supply wiring 81 connected to one end of the heater portion 6 and a second power supply wiring 82 connected to the other end of the heater portion 6. One of the first power supply wiring 81 and the second power supply wiring 82 is connected to a positive electrode, and the other of the first power supply wiring 81 and the second power supply wiring 82 is connected to a negative electrode.

[0040] The heater section 6 includes a first portion 61 having a thickness smaller than that of the power supply wiring 8, and a second portion 62 having a thickness equal to that of the power supply wiring 8. The first portion 61 and the second portion 62 are arranged in the circumferential direction. In this embodiment, four first portions 61 and four second portions 62 are provided. The thicknesses of the four first portions 61 are equal. The thicknesses of the four second portions 62 are equal. The circumferential lengths of the first portions 61 and the second portions 62 are equal. Therefore, since the heater section 6 includes the first portion 61, the electrical resistance of the heater section 6 is greater than the electrical resistance of the power supply wiring 8. The number of the first portions 61 and the second portions 62 is not limited to the above number. As in the first embodiment, the thickness of the first portion 61 and the number of the first portions 61 and the second portions 62 of the heater section 6 are adjusted during the manufacture of the flexible printed circuit board 3 so that the heater section 6 has a desired heat generation amount. Therefore, the electrical resistance of the heater portion 6 can be easily adjusted.

[0041] Third embodiment Next, a flexible printed circuit board 3 according to a third embodiment will be described. Fig. 5 is a plan view of the flexible printed circuit board 3 according to the third embodiment. Note that the same components as those in the first embodiment are given the same reference numerals, and the description thereof may be omitted.

[0042] The heater portion 6 is disposed in the annular portion 31. The heater portion 6 extends in an arc shape in the circumferential direction along the periphery of the opening hole 33. The power supply wiring 8 is disposed in the extension portion 32. The power supply wiring 8 includes a first power supply wiring 81 connected to one end of the heater portion 6 and a second power supply wiring 82 connected to the other end of the heater portion 6. One of the first power supply wiring 81 and the second power supply wiring 82 is connected to a positive electrode, and the other of the first power supply wiring 81 and the second power supply wiring 82 is connected to a negative electrode.

[0043] The heater portion 6 includes a first portion 61 that is thinner than the thickness of the power supply wiring 8, and a second portion 62 that is the same thickness as the power supply wiring 8. The first portion 61 and the second portion 62 are arranged in the circumferential direction. Four first portions 61 are provided, and six second portions 62 are provided. The four first portions 61 have the same thickness. The six second portions 62 have the same thickness.

[0044] In this embodiment, the circumferential length of the first portion 61 disposed at the position farthest from the connection portion 67 electrically connected to the power supply wiring 8 is longer than the circumferential length of the other first portions 61. Specifically, the first portion 61a disposed at the position farthest from the connection portion 67 electrically connected to the power supply wiring 8 is longer in the circumferential length than the other first portions 61b and 61c. Also, the first portion 61b is longer in the circumferential length than the first portion 61c. Therefore, the electrical resistance of the first portion 61a is greater than the electrical resistance of the other first portions 61b and 61c, and therefore the amount of heat generated in the first portion 61a is greater than the amount of heat generated in the other first portions 61b and 61c.

[0045] As in the second embodiment, the thickness of the first portion 61 of the heater portion 6, the circumferential length of the first portion 61, and the number of the first portions 61 and the second portions 62 are adjusted during the manufacture of the flexible printed circuit board 3 so that the heater portion 6 has a desired heat generation amount. Therefore, by adjusting the thickness of the heater portion 6, it is easy to adjust the heat generation amount of the heater portion 6. In addition, since the heat generation amount of the first portion 61a can be made larger than the heat generation amount of the other first portions 61b and 61c, the heater portion 6 can be heated uniformly. As a result, it is possible to more efficiently remove condensation generated on the first lens L1.

[0046] (Fourth embodiment) Next, a flexible printed circuit board 3 according to a fourth embodiment will be described. Fig. 6 is a plan view of the flexible printed circuit board 3 according to the fourth embodiment. Note that the same components as those in the first embodiment are given the same reference numerals, and the description thereof may be omitted.

[0047] The heater portion 6 is disposed in the annular portion 31. The heater portion 6 extends in an arc shape in the circumferential direction along the periphery of the opening hole 33. The power supply wiring 8 is disposed in the extension portion 32. The power supply wiring 8 includes a first power supply wiring 81 connected to one end of the heater portion 6 and a second power supply wiring 82 connected to the other end of the heater portion 6. One of the first power supply wiring 81 and the second power supply wiring 82 is connected to a positive electrode, and the other of the first power supply wiring 81 and the second power supply wiring 82 is connected to a negative electrode.

[0048] The thickness of the heater section 6 is thinner than that of the power supply wiring 8, and becomes thinner as it moves away from the connection portion 67 electrically connected to the power supply wiring 8 in the circumferential direction. Specifically, the thickness of the heater section 6 becomes thinner from the connection portion 67 electrically connected to the power supply wiring 8 toward the opposite portion 66 located on the opposite side of the connection portion 67 with respect to the optical axis L as the center. That is, the opposite portion 66 of the heater section 6 has the thinnest thickness. Therefore, the electrical resistance of the heater section 6 increases from the connection portion 67 toward the opposite portion 66, so that the amount of heat generated in the opposite portion 66 is greater than the amount of heat generated in other portions. In addition, by adjusting the thickness of the heater section 6, it is easy to adjust the amount of heat generated in the heater section 6. In addition, since the amount of heat generated in the opposite portion 66 can be made greater than the amount of heat generated in other portions, the heater section 6 can be heated uniformly. As a result, it is possible to more efficiently remove condensation generated on the first lens L1.

[0049] Fifth embodiment Next, a flexible printed circuit board 3 according to a fifth embodiment will be described. Fig. 7 is a plan view of the flexible printed circuit board 3 according to the fifth embodiment. Note that the same components as those in the first embodiment are given the same reference numerals, and the description thereof may be omitted.

[0050] The heater section 6 is disposed in the annular section 31. The heater section 6 extends in an arc shape in the circumferential direction along the periphery of the opening hole 33. The power supply wiring 8 is disposed in the extension section 32. The heater section 6 includes a first power supply wiring 81 connected to one end of the heater section 6 and a second power supply wiring 82 connected to the other end of the heater section 6. One of the first power supply wiring 81 and the second power supply wiring 82 is connected to a positive electrode, and the other of the first power supply wiring 81 and the second power supply wiring 82 is connected to a negative electrode. In this embodiment, the thickness of the heater section 6 is equal to the thickness of the power supply wiring 8.

[0051] The heater section 6 has a plurality of holes 68. In this embodiment, the holes 68 are uniformly provided. The holes 68 have the same size. Therefore, by providing the heater section 6 with a plurality of holes 68, the electrical resistance of the heater section 6 is greater than the electrical resistance of the power supply wiring 8.

[0052] As in the above embodiment, the number and size of holes 68 formed in the heater section 6 are adjusted during manufacturing of the flexible printed circuit board 3 so that the heater section 6 has a desired heat generation amount. Therefore, simply by providing a plurality of holes 68 in the heater section 6, it is easy to make the electrical resistance of the heater section 6 greater than the electrical resistance of the power supply wiring 8. As a result, it is easy to adjust the heat generation amount of the heater section 6.

[0053] Sixth embodiment Next, a flexible printed circuit board 3 according to a sixth embodiment will be described. Fig. 8 is a plan view of the flexible printed circuit board 3 according to the sixth embodiment. Note that the same components as those in the first embodiment are given the same reference numerals, and the description thereof may be omitted.

[0054] This embodiment is the same as the fifth embodiment, except that the plurality of holes 68 formed in the heater section 6 are not uniformly formed. In this embodiment, the plurality of holes 68 are provided so that their number increases with increasing distance in the circumferential direction from a connection portion 67 electrically connected to the power supply wiring 8. That is, the opposite portion 66 of the heater section 6 has the greatest number of holes 68 formed therein. Therefore, the electrical resistance of the heater section 6 increases from the connection portion 67 toward the opposite portion 66, and therefore the amount of heat generated in the opposite portion 66 is greater than the amount of heat generated in other portions.

[0055] As in the above embodiment, the number and size of holes 68 formed in heater section 6 are adjusted during manufacturing of flexible printed circuit board 3 so that heater section 6 generates a desired amount of heat. In this embodiment, the amount of heat generated in opposite section 66 can be made greater than the amount of heat generated in other sections, so heater section 6 can be heated uniformly. As a result, condensation that occurs on first lens L1 can be removed more efficiently.

[0056] (Other embodiments) Next, flexible printed circuit boards 3 according to other embodiments will be described. In the above third and fourth embodiments, the thicknesses of the first portions 61 are configured to be equal to each other, but they may be configured to be different from each other. For example, the thickness of the first portion 61 disposed at the position farthest from the connection portion 67 may be configured to be the thinnest.

[0057] (Modification of heater part) In the above configuration, the line width of the heater section 6 is wider than the line widths of the first power supply wiring 81 and the second power supply wiring 82 when viewed from the optical axis L direction, but the shape of the heater section 6 is not limited to this. As shown in Fig. 9, the heater section 6 may be configured to include a heater wire 60 (linear portion) folded back multiple times in the circumferential direction. That is, in the above first to sixth embodiments, the heater section 6 may employ a heater wire 60 folded back multiple times in the circumferential direction. [Explanation of symbols]

[0058] 1...lens unit, 2...lens holder, 3...flexible printed circuit board, 5...holder, 5...first, 6...heater portion, 7...O-ring, 8...power supply wiring, 9...conductive layer, 11...object side lens surface, 12...image side lens surface, 13...image side flange surface, 14...annular step portion, 21...first housing portion, 22...second housing portion, 23...lens case, 24...bottom portion, 25...peripheral wall portion, 26...through hole, 27...crimping portion, 28...tubular portion, 28a...crimping portion, 29...bottom portion, 2 9a...lens seat surface, 30...flexible substrate, 31...annular portion, 32...extension portion, 33...opening hole, 60...heater wire, 61, 61a, 61b, 61c...first portion, 62...second portion, 66...opposite portion, 67...connection portion, 68...hole portion, 81...first power supply wiring, 82...second power supply wiring, L1...first lens, L2...second lens, L3...third lens, L4...fourth lens, L5...fifth lens, L6...sixth lens, L7...light shielding plate, L9...cemented lens, L...optical axis

Claims

1. A first lens; A second lens disposed on an image side relative to the first lens; a lens holder that holds a plurality of lenses including the first lens and the second lens; a flexible printed circuit board provided with a conductive layer; having the first lens comprises an image-side lens surface and an image-side flange surface surrounding the image-side lens surface, the flexible printed circuit board includes an annular portion overlapping the image side flange surface, and an extension portion extending radially outward from the annular portion, the conductive layer includes a heater portion extending in an arc shape in a circumferential direction along the annular portion, and a power supply wiring extending from the heater portion along the extension portion, the electrical resistance of the heater portion is greater than the electrical resistance of the power supply wiring, the heater portion includes a first portion having a thickness smaller than that of the power supply wiring and a second portion having a thickness equal to that of the power supply wiring; The first portion and the second portion are arranged in a plurality of portions in a circumferential direction, A lens unit characterized in that, among the plurality of first portions, the first portion that is located at a position farthest from a connection portion where the power supply wiring and the heater portion are electrically connected has a circumferential length longer than the circumferential lengths of the other first portions.

2. A first lens; A second lens disposed on an image side relative to the first lens; a lens holder that holds a plurality of lenses including the first lens and the second lens; a flexible printed circuit board provided with a conductive layer; having the first lens comprises an image-side lens surface and an image-side flange surface surrounding the image-side lens surface, the flexible printed circuit board includes an annular portion overlapping the image side flange surface, and an extension portion extending radially outward from the annular portion, the conductive layer includes a heater portion extending in an arc shape in a circumferential direction along the annular portion, and a power supply wiring extending from the heater portion along the extension portion, the electrical resistance of the heater portion is greater than the electrical resistance of the power supply wiring, The heater portion includes a plurality of holes. The lens unit according to claim 1, wherein the number of the holes increases with increasing distance in a circumferential direction from a connection portion where the power supply wiring and the heater portion are electrically connected.

3. 3. The lens unit according to claim 1, The lens unit according to claim 1, wherein the heater portion has a thickness smaller than a thickness of the power supply wiring.

4. 3. The lens unit according to claim 1, The lens unit according to claim 1, wherein the thickness of the heater portion decreases with increasing distance in the circumferential direction from a connection portion where the power supply wiring and the heater portion are electrically connected.

5. The lens unit according to any one of claims 1 to 4, The lens unit according to claim 1, wherein the heater portion includes a linear portion folded back a number of times in a circumferential direction.

Images