Lens unit and camera module

Abstract

To provide a lens unit and a camera module which can stably and reliably heat a first lens positioned closest to an object by a planar heater.SOLUTION: A lens unit includes: a plurality of lenses arrayed along an optical axis; a lens barrel 12 for storing and holding the plurality of lenses; and a planar heater 50 capable of heating a first lens 13 positioned closest to an object. The planar heater 50 includes a heating part 51 for heating the first lens 13. The heating part 51 is bonded to an end surface 13a on the image side of the first lens 13 by an adhesive so that the first lens 13 can be stably and reliably heated by the planar heater 50.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Cameras installed outdoors such as surveillance cameras and on-vehicle cameras are known. In such cameras installed outdoors, ice and snow may adhere to the front surface of the lens during snowfall. Further, when the outside air temperature drops below the freezing point, the front surface of the lens may freeze and frost may adhere thereto. In such a case, the captured image becomes unclear due to the deposits on the front surface of the lens, and the imaging performance of the camera degrades. In recent years, cameras (on-vehicle cameras) have come to be mounted on vehicles, and images captured by on-vehicle cameras are used for functions such as automatic braking functions and automatic driving functions. These functions are functions that control the traveling of the vehicle, and a decrease in the imaging function of the on-vehicle camera may lead to the occurrence of accidents and the like. Therefore, development of a camera having a snow melting function for melting deposits adhering to the front surface of a lens is demanded. Further, since the side of the lens unit of an on-vehicle camera facing the imaging target (object side) is exposed to the outside of the vehicle, strength, water resistance, chemical resistance, high temperature durability and the like are required. Further, it is necessary to prevent fogging of the lens due to temperature changes.

[0003] Patent Document 1 discloses a lens unit that ensures an airtight state inside a 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, sealing performance is achieved by disposing an O-ring between the lens closest to the object side and the inner peripheral surface of the lens barrel. On the image side (imaging element side), sealing performance is achieved by attaching an optical filter to the lens barrel via an adhesive. In this way, airtightness inside the lens barrel is ensured by the seal on the object side and the seal on the image forming side, and fogging of the lens is prevented. [Prior Art Literature] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2008-233512 [Overview of the project] [Problems that the invention aims to solve]

[0005] Incidentally, as mentioned above, even if the inside of the lens barrel is kept airtight, if the difference between the outside temperature and the temperature inside the lens unit becomes large, water vapor inside the lens unit will condense and form condensation on the lens surface. In particular, condensation is most likely to occur in the interlens space between the first lens (the lens closest to the object) and the adjacent second lens, where the effect of the temperature difference with the outside is greatest, especially on the back surface of the first lens.

[0006] Therefore, in order to remove condensation from 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 the shape of a donut plate and includes a heating section that heats the first lens and a strip-shaped extension that extends from the heating section and supplies electricity to the heating section. The heating element of such a planar heater is positioned so as to be sandwiched between a first lens and a lens or spacer adjacent to the first lens in the optical axis direction. However, when the lens unit experiences temperature changes due to the environment, especially at high temperatures, a gap may form between the lens barrel and the lens or spacer housed inside due to differences in the coefficient of linear expansion. If this gap creates a gap between the first lens and the heating element of the planar heater, air will be interposed in the gap, reducing thermal conductivity and making it difficult to stably and reliably heat the first lens with the heating element. In addition to the ambient temperature changes mentioned above, there are also temperature changes due to heating by the heater, and in this case as well, there is a problem in that it becomes difficult to heat the first lens stably and reliably.

[0007] The present invention has been made in view of the above circumstances, and aims to provide a lens unit and camera module that can stably and reliably heat the first lens, which is located closest to the object, with a planar heater. [Means for solving the problem]

[0008] To solve the aforementioned problems, the present invention provides a lens unit comprising a plurality of lenses arranged along the optical axis, a lens barrel that houses and holds these plurality of lenses, and a planar heater capable of heating the first lens located closest to the object, The planar heater includes a heating section for heating the first lens, The heating element is characterized by being bonded to the image-side end face of the first lens with an adhesive.

[0009] Examples of planar heaters include FPC heaters and organic PTC heaters. Such planar heaters are formed in the shape of a donut plate and include a heating section that heats the first lens and a strip-shaped extension that extends from the heating section and supplies electricity to the heating section. For the adhesive, it is preferable to use an epoxy resin, such as an epoxy resin containing conductive fillers, which has excellent thermal conductivity.

[0010] In this invention, since the heating element of the planar heater is bonded to the image-side end face of the first lens with an adhesive, even if the lens unit experiences temperature changes due to the environment, especially when it becomes very hot, and a gap forms between the lens barrel and the second lens or spacer housed inside it, no gap forms between the first lens and the heating element of the planar heater. Therefore, no air is trapped in the gap. As a result, the thermal conductivity does not decrease, and thus the first lens can be heated stably and reliably by the heating element.

[0011] Furthermore, in the above configuration of the present invention, the first lens and the second lens or spacer are adjacent to each other in the optical axis direction and are in contact with each other. A gap may be provided between the first lens and the second lens or the spacer to accommodate the heating portion of the planar heater.

[0012] With this configuration, the heating element of the planar heater can be housed in the gap, making it easy to position the heating element.

[0013] Furthermore, in the above configuration of the present invention, the planar heater may be an FPC heater or an organic PTC heater.

[0014] Furthermore, in the above configuration of the present invention, the planar heater is an organic PTC heater, A gap may be provided between the second lens or spacer adjacent to the first lens in the optical axis direction and the heating portion of the organic PTC heater.

[0015] Organic PTC heaters may become difficult to use if the heating element is pressurized in the thickness direction, as the electrical resistance increases. In contrast, with the above configuration, a gap is provided between the second lens or spacer adjacent to the first lens in the optical axis direction and the heating element of the organic PTC heater. Therefore, the heating element is not pressed against the first lens by being sandwiched between the first lens and the lens or spacer adjacent to the first lens in the optical axis direction. For this reason, the organic PTC heater can be used easily.

[0016] Furthermore, in the above configuration of the present invention, the planar heater includes a strip-shaped extension that extends from the heating section and supplies electricity to the heating section, An insertion portion is provided on the outer circumference of a second lens or spacer adjacent to the first lens in the optical axis direction, allowing the extension of the planar heater to be inserted along the axial direction of the lens barrel. The lens barrel may be provided with an outlet hole in communication with the insertion portion for leading out the extension portion inserted into the insertion portion to the outside.

[0017] Here, the insertion portion may be an insertion groove or an insertion hole provided in the outer peripheral portion of the second lens or spacer adjacent to the first lens in the optical axis direction. In this case, it is preferable that the groove width of the insertion groove or the inner diameter of the insertion hole is wider than the width of the extension portion.

[0018] According to this configuration, the insertion portion for inserting the extension portion of the sheet heater along the axial direction of the lens barrel is provided on the outer peripheral portion of the second lens or spacer adjacent to the first lens in the optical axis direction. Therefore, by inserting the extension portion into the insertion portion, the extension portion can be easily routed within the lens barrel. Furthermore, a lead-out hole for leading the extension portion inserted into the insertion portion to the outside is provided in the lens barrel so as to communicate with the insertion portion, so the extension portion inserted into the insertion portion can be easily led out to the outside through the lead-out hole.

[0019] Further, in the configuration of the present invention, the adhesive may be a thermosetting adhesive.

[0020] According to this configuration, the heating portion of the sheet heater is bonded to the image-side end surface of the first lens with a thermosetting adhesive. Therefore, when a blackened portion for preventing ghosting is provided on the image-side end surface of the first lens, a UV-curable adhesive cannot bond the heating portion to the image-side end surface of the first lens, but a thermosetting adhesive can achieve reliable bonding.

[0021] Further, a camera module according to the present invention is characterized by comprising the lens unit described above. According to this configuration, the camera module can obtain the operational effects of the lens unit described above.

Effects of the Invention

[0022] According to the present invention, the first lens located closest to the object side can be stably and reliably heated by the sheet heater.

Brief Description of Drawings

[0023] [Figure 1] FIG. 1 is a schematic cross-sectional view of a lens unit, showing a first embodiment of the present invention. [Figure 2] Similarly, (a) is a plan view showing the first example of the telescope tube, and (b) is a plan view showing the second example of the telescope tube. [Figure 3] This is a perspective view of the telescope tube from an oblique angle above. [Figure 4] This is a perspective view of the same telescope tube, taken from another angle above. [Figure 5] This diagram schematically shows the lens supported by the housing and holding section. [Figure 6] This is a schematic cross-sectional view of the camera module. [Figure 7] This is a plan view of the FPC heater. [Figure 8] This is a plan view showing the lens and spacer. [Figure 9] This is a plan view showing the spacer housed and held within the telescope tube. [Figure 10] This is a schematic cross-sectional view of a lens unit, illustrating a second embodiment of the present invention. [Figure 11] This is a plan view of the spacer. [Modes for carrying out the invention]

[0024] Embodiments of the present invention will be described below with reference to the drawings. The lens unit of this embodiment, described below, is particularly intended for camera modules such as in-vehicle cameras. For example, it is fixedly installed on the exterior surface of a vehicle, and the wiring is routed into the vehicle and connected to a display or other device. Also, hatching is omitted for the lens and spacer in all figures.

[0025] (First Embodiment) Figure 1 shows a lens unit 11 according to a first embodiment of the present invention. As shown in the figure, the lens unit 11 of this embodiment includes, for example, a cylindrical lens barrel 12 made of resin, a plurality of circular lenses in plan view arranged inside the lens barrel 12, for example, five lenses consisting of a first lens 13, a second lens 14, a third lens 15, a fourth lens 16, and a fifth lens 17 from the object side (upper side in Figure 1), and three aperture members 22a, 22b, and 22c. Furthermore, a groove is provided on the bottom surface of the lens barrel 12, extending radially from the inner circumference of the bottom surface of the lens barrel 12 toward the part that is not in contact with the lens 17. This groove is for the circulation of air for airtightness testing.

[0026] Of the three aperture members 22a, 22b, and 22c, the first aperture member 22a from the object side is positioned between the second lens 14 and the third lens 15. The second aperture member 22b from the object side is positioned between the third lens 15 and the fourth lens 16. The third aperture member 22c from the object side is positioned between the fourth lens 16 and the fifth lens 17. The aperture member 22a is an "aperture diaphragm" that limits the amount of transmitted light and determines the F-number, which is an indicator of brightness. The aperture 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 equipped with such a lens unit 11 comprises the lens unit 11, a substrate having an image sensor (not shown), and mounting members (not shown) for mounting the substrate in a vehicle such as an automobile.

[0027] Multiple lenses 13, 14, 15, 16, and 17 housed within the lens barrel 12 are stacked and arranged with their optical axes aligned. Each lens 13, 14, 15, 16, and 17 is aligned along a single optical axis O, forming a lens group L used for imaging. In this case, the first lens 13, located closest to the object, is a spherical glass lens with a flat surface on the object side and a concave surface on the image side, while the second lens 14 is a spherical glass lens with convex surfaces on both the object and image sides. The other lenses 15, 16, and 17 are resin lenses, but are not limited to these (for example, the first lens 13 and the second lens 14 may be resin lenses; if the first and second lenses 13 and 14 are made of resin, for example, the difference in their coefficients of thermal expansion is 40 × 10⁻⁶). -6 (It may be greater than or equal to / K(m)).

[0028] Furthermore, the lens barrel 12 is provided with a spacer 30 between the first lens 13 and the third lens 15, and has an interlens 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 bonded to each other so that the inside of the interlens space SL is sealed from the outside. The number of lenses, the number of spacers, and the materials of the lenses, spacers, and lens barrel can be arbitrarily set according to the application. Furthermore, the surfaces of these lenses 13, 14, 15, 16, and 17 may be coated with an anti-reflective coating, a hydrophilic coating, a water-repellent coating, or the like, as needed.

[0029] The spacer 30 is formed in a cylindrical shape, and the second lens 14 is held at its inner lower end. Specifically, the spacer 30 has a crimped portion 31 at its inner diameter lower end edge, and this crimped portion 31 is thermally crimped radially inward by pressing 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, the crimping portion 31 presses the opposing surface 14a of the second lens 14 against the opposing surface 30b of the spacer 30, thereby holding the second lens 14 in place on the spacer 30.

[0030] Furthermore, in this embodiment, an O-ring 26 is interposed between the first lens 13, which is located closest to the object, 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 diameter reduction portion 13e is provided on the outer circumferential surface 13d of the first lens 13, where the diameter is smaller on the image side of the lens 13. The O-ring 26 is fitted onto this diameter reduction portion 13e, and the O-ring 26 is compressed radially between the outer circumferential surface 13d of the first lens 13 and the inner circumferential surface 12a of the lens barrel 12, thereby sealing the object-side end of the lens barrel 12. Furthermore, the sealing member interposed between the first lens 13 and the lens barrel 12 is not limited to an O-ring 26, but can be any form of annular body that can seal the space between the first lens 13 and the lens barrel 12.

[0031] Furthermore, with the lens group L assembled and housed within the lens barrel 12, the crimping portion 23 at the object-side end (upper end in Figure 1) is thermally crimped radially inward, thereby fixing the first lens 13, which is located closest to the object in the lens group L, to the object-side end of the lens barrel 12 in the optical axis direction. In this case, to ensure stable crimping, the portion of the glass lens 13 to which the crimping portion 23 is pressed is formed as a flat portion 13b that is cut diagonally in a planar shape.

[0032] Furthermore, the lens barrel 12 has an inner flange portion 24 at the image-side end (lower end in Figure 1) that has an opening with a smaller diameter than the fifth lens 17. The multiple lenses 13, 14, 15, 16, 17 and aperture members 22a, 22b, 22c, 22d that constitute the lens group L are held and fixed in the optical axis direction within the lens barrel 12 by this inner flange portion 24 and the crimping portion 23.

[0033] The lens barrel 12 includes a housing and holding section S that houses and holds the lenses 15, 16, 17 and the spacers 30 provided between adjacent lenses 13, 15 in the optical axis direction. As shown in Figures 2 and 3, the storage and holding section S has an inner circumferential surface formed in a polygonal shape with octagons or more. In this embodiment, however, the shape is a combination of 12 straight edges (chords) arranged at predetermined intervals in the circumferential direction and 12 circular arcs arranged to connect adjacent edges (chords) in the circumferential direction. Furthermore, the inner diameter of the housing and holding section S decreases in stages from the object side towards the image side. Correspondingly, the outer diameters of the spacer 30 and lenses 15, 16, and 17 decrease as they move from the object side towards the image side. Basically, the outer diameters of the spacer 30 and lenses 15, 16, and 17 are approximately equal to the inner diameters of the parts of the housing and holding section S of the lens barrel 12 that support the spacer 30 and each of the lenses 15, 16, and 17.

[0034] Specifically, to describe the lens 15 as an example, as schematically shown in Figure 5, the housing and holding portion S has a regular dodecagonal shape on its inner circumferential surface, giving it 12 planar support surfaces SS, which are adjacent to each other in the circumferential direction at equal angles. The circumferential center of each support surface SS is a support point SP that supports the outer circumferential surface of the lens 15, and there are 12 such support points SP. Therefore, the lens 15 is stably supported by the 12 support points SP in a direction perpendicular to the optical axis. As mentioned above, Figure 2 shows a shape formed by a combination of 12 straight edges (chords) arranged at predetermined intervals in the circumferential direction and 12 circular arcs arranged to connect adjacent edges (chords) in the circumferential direction. However, in the following description, it will be explained as a regular dodecagon.

[0035] Similarly, the housing and holding section S that houses and holds the spacer 30 and lenses 16 and 17 also has an inner circumferential surface formed in a regular dodecagon shape, but the outer diameter (the distance between support points SP arranged point-symmetrically with respect to the optical axis) decreases in stages from the object side toward the image side. In addition, the lenses 16 and 17 are each stably supported in a direction perpendicular to the optical axis by 12 support points SP, but as will be described later, the spacer 30 is stably supported in a direction perpendicular to the optical axis by 10 support points SP because the housing and holding section S has an insertion groove 55.

[0036] Here, as shown in Figures 1 to 3, the housing and holding section S is composed of a first housing and holding section S1 for housing and holding the spacer 30, a second housing and holding section S2 for housing the lens 15, a third housing and holding section S3 for housing the lens 16, and a fourth housing and holding section S4 for housing the lens 17, with the inner diameter decreasing in stages from the first housing and holding section S1 to the fourth housing and holding section S4. Furthermore, a stepped surface protruding radially inward is provided between adjacent housing and holding sections in the axial direction of the lens barrel 12. Furthermore, in the housing and holding section S shown in Figure 2(a), one vertex of the regular dodecagon is positioned toward the center in the width direction of the insertion groove 55, which will be described later, whereas in the housing and holding section S shown in Figure 2(b), one vertex of the regular dodecagon is positioned toward a position rotated 15° circumferentially from the center in the width direction of the insertion groove 55. In both cases, the spacer 30 is supported by 10 support points SP.

[0037] Furthermore, the housing and holding portion SU that houses the lens 13 closest to the object has a circular inner surface, and the lens 13 is housed and held in this housing and holding portion SU. Furthermore, the second lens 14 is formed to have a smaller diameter than lenses 13, 15, 16, and 17, and is held and fixed by the spacer 30. Furthermore, an outer flange portion 25, used when mounting the lens barrel 12 to an in-vehicle camera, is provided on the outer surface of the lens barrel 12 in a flange-like manner.

[0038] Figure 6 is a schematic cross-sectional view of the camera module 300 of this embodiment, which has the lens unit 11 shown in Figure 1. As shown, the camera module 300 is configured to include the lens unit 11 to which the filter 105 is attached.

[0039] The camera module 300 comprises an outer casing (not shown) and a mount (base) 302 that holds the lens unit 11. The camera module 300 also includes a sealing member 303 and a package sensor (image sensor) 304.

[0040] The upper case is a component that exposes the object-side end of the lens unit 11 while covering the other parts. The mount 302 is located inside the upper case and has a female thread 302a that screws into the male thread 11a of the lens unit 11. The package sensor 304 is located inside the mount 302 and is positioned to receive the image of the object formed by the lens unit 11. The package sensor 304 is equipped with a CCD or CMOS sensor and converts the light that is focused and reaches it through the lens unit 11 into an electrical signal. The converted electrical signal is then converted into analog or digital data, which are components of the image data captured by the camera.

[0041] As shown in Figures 1 and 7, the lens unit 11 and camera module 300, having the configuration described above, are equipped with an FPC heater (planar heater) 50 capable of heating the lens 13 located closest to the object. An organic PTC heater may also be used as the planar heater. As shown in Figure 7, the FPC heater 50 is formed from a flexible printed circuit board and includes a heating section 51 that heats the first lens 13 and an extension section 52 that extends from the heating section 51 and supplies electricity to the heating section 51. The heating section 51 is formed in the shape of a donut plate, with an outer diameter approximately equal to the outer diameter of the image-side end face 13a of the first lens 13, and an inner diameter approximately equal to the inner diameter of the image-side end face 13a of the first lens 13. The heating section 51 is formed by creating a semicircular circuit section on a donut-shaped base film, where a thin linear copper foil 51a is folded inward from the outer circumference to form a semicircular arc, and this circuit section generates heat. The extension portion 52 extends linearly radially outward from the heating portion 51 and is formed by arranging two strip-shaped copper foils 52a parallel to each other on a strip-shaped base fill portion, with one copper foil 52a connected to the anode of the power supply and the other copper foil 52a connected to the cathode.

[0042] As shown in Figures 2 and 3, the housing and holding section S is provided with a through groove (through section) 55 that extends in the axial direction of the lens barrel 12. This through groove 55 has a groove width wider than the width of the extension section 52 of the FPC heater 50, and a groove depth deeper than the thickness of the extension section 52. Furthermore, the through groove 55 extends from the object-side end of the first housing and holding section S1 to a position slightly closer to the object than the image-side end of the first housing and holding section S1. The heating element 51 of the FPC heater 50 is bonded to the image-side end face 13a of the lens 13 with an adhesive. A thermosetting adhesive with excellent thermal conductivity is used. For example, epoxy resin, epoxy resin containing conductive fillers, etc., are suitably used. The thermal conductivity of the adhesive is preferably 0.2 to 2.0 W / m·K. The adhesive is applied evenly and uniformly to the upper surface (the surface facing the first lens 13) of the heating element 51 of the FPC heater 50 and / or to the image-side end face 13a of the first lens 13, and then these upper surface and end face 13a are bonded together. It is preferable to apply the adhesive evenly, but it may also be applied to multiple predetermined areas before bonding. The extension portion 52 is oriented toward the insertion groove 55 and is inserted into the insertion groove 55.

[0043] Furthermore, an outlet hole 56 is provided in the peripheral wall of the lens barrel 12, communicating with the insertion groove 55. The outlet hole 56 is rectangular in shape, and its width is equal to the width of the insertion groove 55. The outlet hole 56 is formed to penetrate the peripheral wall of the lens barrel 12. The exit of the outlet hole 56 is located in the peripheral wall of the lens barrel 12 above the outer flange portion 25. Such an exit hole 56 is for leading out the extension portion 52 of the FPC heater 50, which is inserted into the insertion groove 55, to the outside of the lens barrel 12. The extension portion 52, which is inserted into the insertion groove 55, is bent radially outward at approximately a right angle at the entrance of the exit hole 56, and then inserted into the exit hole 56 and led out to the outside. The insertion groove 55 may be extended to the upper surface of the inner flange portion 24, and an outlet hole may be provided in the inner flange portion 24, penetrating in the thickness direction of the inner flange portion 24.

[0044] When the heating portion 51 of the FPC heater 50 is bonded to the image-side end face 13a of the first lens 13 with adhesive, and the extension portion 52 of the FPC heater 50 is led out to the outside of the lens barrel 12, the procedure is as follows. First, the aperture member 22d, lens 17, aperture member 22c, lens 16, aperture member 22b, lens 15, and aperture member 22a are inserted into the lens barrel 12 in order, starting from the opening on the object side (the upper end side in Figure 1). On the other hand, the spacer 30 and lens 14 are pre-assembled as an assembly outside the lens barrel 12. Furthermore, the upper surface of the heating element 51 of the FPC heater 50 is attached to the end face 13a of the first lens 13 on the outside of the lens barrel 12 using adhesive.

[0045] Next, after inserting the assembly into the lens barrel 12, the first lens 13, to which the heating portion 51 of the FPC heater 50 is bonded, is inserted into the lens barrel 12. At this time, the first lens 13 is positioned circumferentially so that the extension portion 52 of the FPC heater 50 faces the insertion groove 55, and the extension portion 52 is inserted into the insertion groove 55. Once the extension portion 52 is inserted into the insertion groove 55 and its tip reaches the exit hole 56, the extension portion 52 is bent radially outward and inserted outward along the exit hole 56, and is led out to the outside of the lens barrel 12. Then, while pulling the extended portion 52, the first lens 13 to which the heating portion 51 of the FPC heater 50 is bonded is inserted into the lens barrel 12, and finally, the crimping portion 23 is thermally crimped radially inward to fix the lens group L inside the lens barrel 12. Furthermore, when inserting the first lens 13 into the lens barrel 12, the O-ring 26 should be attached to the first lens 13 beforehand.

[0046] However, the method is not limited to this, and may also be as follows: Before inserting the assembly into the lens barrel 12, with the first lens 13 to which the heating portion 51 of the FPC heater 50 is bonded extended to the outside of the lens barrel 12, the extension portion 52 is inserted into the insertion groove 55, and then into the exit hole 56 to be led out to the outside of the lens barrel 12. Next, the assembly is inserted into the lens barrel 12, the first lens 13 which had been left outside is inserted into the lens barrel 12, and finally, the lens group L is fixed inside the lens barrel 12 by thermally crimping the crimping portion 23 radially inward.

[0047] Furthermore, in this embodiment, as shown in Figure 2, the angle θ formed by the line connecting both ends of the insertion groove 55 in the width direction and the center O of the housing and holding portion S (first housing and holding portion S1) is within 60°. As shown in Figure 2(a), the first housing and holding portion S1 has an inner circumferential surface formed in the shape of a regular polygon with a dodecagon or more. However, a portion of this inner circumferential surface is cut out in the shape of a rectangular groove, so that two of the twelve support surfaces SS are removed. Therefore, the spacer 30 is supported by 10 support points SP. For this reason, even if an insertion groove 55 is formed, the spacer 30 can be stably supported. Furthermore, as shown in Figure 2(b), the first housing and holding portion S1 has an inner circumferential surface formed in a regular polygonal shape of dodecagon or more, but a part of the inner circumferential surface is cut out in the shape of a rectangular groove, so that one support surface SS and less than half of two support surfaces SS are removed out of the 12 support surfaces SS. 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.

[0048] As shown in Figure 8, the lenses 15-17 and the spacer 30 have an outer diameter formed by a cylindrical surface, but a flat surface 30a is formed on a part of the cylindrical surface, resulting in a D-cut shape. It is preferable to arrange the D-cut portion of this D-cut shape so that it faces the insertion groove 55. The same applies to the second embodiment described later. The flat surface 30a is the gate portion when forming the lenses 15-17 and the spacer 30, and this flat surface 30a is not originally in contact with the support surface SS of the first housing and holding portion S1. Therefore, as shown in Figure 9, by placing 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 placed in the insertion groove 55 and the bottom surface of the insertion groove 55 for the extension portion 52 of the FPC heater 50 to be inserted.

[0049] Furthermore, in this embodiment, as shown in Figure 2, the groove width W of the insertion groove 55 is 3.5 mm or less. As described above, if the groove width of the insertion groove 55 is set to an angle θ of 60° or less, the groove width of the insertion groove 55 will increase as the outer diameter of the spacer 30 increases. In order to prevent it from becoming excessive, the groove width W of the insertion groove 55 is specified to be 3.5 mm or less.

[0050] As described above, according to this embodiment, since the heating element 51 of the FPC heater (planar heater) 50 is bonded to the image-side end face 13a of the first lens 13 with adhesive, even if the lens unit 11 changes temperature due to the environment and becomes particularly hot, creating a gap between the lens barrel 12 and the spacer 30 housed and held inside it, no gap will be created between the first lens 13 and the heating element 51 of the FPC heater 50, thus preventing air from intervening. In this way, since no air is intervening, the thermal conductivity does not decrease, and therefore the first lens 13 can be heated stably and reliably by the heating element 51. Furthermore, since the heating element 51 of the FPC heater 50 is bonded to the image-side end face 13a of the first lens 13 with a thermosetting adhesive, if a blackened area for ghost prevention is provided on the image-side end face 13a of the first lens 13, the heating element 51 cannot be bonded to the image-side end face 13a of the first lens 13 with a UV-curing adhesive, but it can be reliably bonded with a thermosetting adhesive.

[0051] Furthermore, the first housing and holding section S1 that houses 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 extension portion 52 of the FPC heater 50. By inserting the extension portion 52 into the insertion groove 55, the extension portion 52 can be easily routed within the lens barrel. Moreover, an outlet hole 56 for leading the extension portion 52 inserted into the insertion groove 55 to the outside is provided in the peripheral wall of the lens barrel 12 and is in communication with the insertion groove 55. Therefore, the extension portion 52 inserted into the insertion groove 55 can be easily led to the outside through the outlet hole 56. Furthermore, since the extension portion 52 of the FCC heater 50 does not interfere with the spacer 30 or the lenses 15, 16, and 17, the spacer 30 and the lenses 15, 16, and 17 will not become eccentric even if the extension portion 52 is routed within the telescope tube 12.

[0052] Furthermore, since the outlet hole 56 is provided in the peripheral wall of the lens barrel 12, the extension 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 and the center of the first housing and holding part S1 is within 60°, the outer surface of the spacer 30 can be held by 10 support points SP in the first housing and holding part S1, whose inner surface is formed as a regular dodecagon, and therefore the spacer 30 can be held stably. In addition, since the groove width of the insertion groove 55 is 3.5 mm or less, the extension portion 52 of the FPC heater 50, which has a width of 3.5 mm or less, can be easily inserted into the insertion groove 55. In this embodiment, the combination of the first lens 13 and the spacer 30 has been described, but a second lens may be used instead of the spacer 30.

[0053] (Second embodiment) Figures 10 and 11 show a second embodiment, where Figure 10 is a cross-sectional view of the lens unit 11 and Figure 11 is a plan view of the spacer 30. The differences between the lens unit 11 of the second embodiment and the lens unit 11 of the first embodiment are the configuration of the spacer, the configuration of the housing and holding portion of the lens barrel 12, and the configuration of the planar heater. Therefore, these points will be explained below, and components identical to those of the first embodiment will be given the same reference numerals and their descriptions may be omitted.

[0054] As shown in Figures 10 and 11, the housing and holding section S has a circular inner surface. Furthermore, the inner diameter of the housing and holding section S gradually decreases from the object side towards the image side. Correspondingly, the outer diameters of the spacer 30 and lenses 15, 16, and 17 decrease from the object side towards the image side. Basically, the outer diameters of the spacer 30 and lenses 15, 16, and 17 are approximately equal to the inner diameters of the parts of the housing and holding section S of the lens barrel 12 that support the spacer 30 and each of the lenses 15, 16, and 17. Furthermore, as shown in Figure 10, the housing and holding section S is composed of a first housing and holding section S1 for housing and holding the spacer 30, a second housing and holding section S2 for housing the lens 15, a third housing and holding section S3 for housing the lens 16, and a fourth housing and holding section S4 for housing the lens 17, with the inner diameter decreasing in stages from the first housing and holding section S1 to the fourth housing and holding section S4. In addition, a stepped surface protruding radially inward is provided between adjacent housing and holding sections in the axial direction of the lens barrel 12.

[0055] Furthermore, in this embodiment, an organic PTC heater 60 is used as the planar heater 60. Due to the property that the resistance of an organic PTC heater increases as the temperature rises, the temperature rises gradually and then stabilizes at a certain temperature. Therefore, it does not require external control such as sensors, can control the appropriate temperature on its own, and once the temperature reaches the upper limit and stabilizes, the power consumption also stabilizes at a low value. There are inorganic PTC heaters and organic PTC heaters as PTC heaters 60, but in this embodiment, an organic PTC heater is preferably used. Similar to the FPC heater 50, this organic PTC heater 60 also includes a heating section 61 that heats the first lens, and a strip-shaped extension 62 that extends from the heating section 61 and supplies electricity to the heating section 61. The heating section 61 is formed in a donut shape, with an outer diameter approximately equal to the outer diameter of the image-side end face 13a of the first lens 13, and an inner diameter approximately equal to the inner diameter of the image-side end face 13a of the first lens 13.

[0056] Furthermore, the heating element 61 of the PTC heater 60 is bonded to the image-side end face 13a of the first lens 13 with adhesive. As with the first embodiment, a thermosetting adhesive with excellent thermal conductivity, such as epoxy resin or epoxy resin containing conductive filler, is used as the adhesive. The adhesive is applied evenly and uniformly to the upper surface (the surface facing the first lens 13) of the heating section 61 of the PTC heater 60 and / or the image-side end face 13a of the first lens 13, and then these upper surface and end face 13a are bonded together. It is preferable to apply the adhesive evenly, but it may also be applied to multiple predetermined locations before bonding.

[0057] Furthermore, the outer circumference of the spacer 30 is provided with an insertion groove (insertion portion) 30d through which the extension portion 62 of the planar heater 60 is inserted along the axial direction of the lens barrel 12. The insertion groove 30d is formed in a rectangular shape in plan view, with a groove width wider than the width of the extension portion 62 and a groove depth (the radial depth of the spacer 30) greater than the thickness of the extension portion 62.

[0058] Furthermore, an outlet hole 56 is provided in the peripheral wall of the lens barrel 12, communicating with the insertion groove 30d. The outlet hole 56 is a rectangular hole, and its width is equal to the groove width of the insertion groove 30d. A rectangular hole 56a is provided in the peripheral wall of the lens barrel 12. This hole 56a is formed to be larger in diameter than the outlet hole 56 and communicates with the outlet hole 56. In addition, the hole 56a is located in the peripheral wall of the lens barrel 12 above the outer flange portion 25. The exit hole 56 is for leading out the extension portion 62 of the PTC heater 60, which is inserted into the insertion groove 30d, to the outside of the lens barrel 12. The extension portion 62, which is inserted into the insertion groove 30d, is bent radially outward at approximately a right angle at the entrance of the exit hole 56, then inserted into the exit hole 56, and further led out to the outside through the hole 56a.

[0059] Furthermore, the first lens 13 and the spacer 30 are adjacent to each other in the optical axis direction and are in contact with each other, and a gap k is provided between the first lens 13 and the spacer 30 to accommodate the heating element 61 of the PTC heater 60. That is, the spacer 30 is formed with a convex outer circumference and a concave inner circumference on the object-facing side, in contact with the first lens 13 on the outer circumference side, and a gap K is provided between the spacer 30 and the first lens 13 on the inner circumference side. Such a gap K may also be provided between the first lens 13 and the spacer 30 in the first embodiment. Furthermore, a gap G is provided between the spacer 30 adjacent to the first lens 13 in the optical axis direction and the heating element 61 of the PTC heater 60. When the heating element 51 of the PTC heater 60 is pressurized in the thickness direction, the electrical resistance value increases, which may make it difficult to use. To prevent such pressurization, a gap G is provided between the spacer 30 and the heating element 61 of the PTC heater 60.

[0060] According to this embodiment, not only can the same effects as in the first embodiment be obtained, but a gap G is provided between the spacer 30 adjacent to the first lens 13 in the optical axis direction and the heating element 61 of the PTC heater 60. Therefore, the heating element 61 is not pressed down by being sandwiched between the first lens 13 and the spacer 30, thus suppressing deterioration of the heater's performance and ensuring a stable output. For this reason, the PTC heater 60 can be used easily.

[0061] In this embodiment, as shown in Figure 10, the outer circumference of the object-side surface of the spacer 30 is convex and the inner circumference is concave, so that it contacts the first lens 13 on the outer circumference and a gap K is formed between the spacer and the first lens 13 on the inner circumference. However, the inner circumference may be convex and the outer circumference concave. Also, although the spacer 30 has a convex shape, the image-side inner or outer circumference of the first lens 13 may also have a convex shape so that it contacts the spacer 30.

[0062] In the first and second embodiments, the storage and holding section S accommodates and holds the spacer 30 and the lenses 15, 16, and 17, but the storage and holding section S may only accommodate and hold a plurality of lenses. In other words, the spacer 30 may be omitted. Furthermore, in the first and second embodiments, the housing and holding portion SU that houses and holds the lens 13 located closest to the object has a circular inner surface, but the housing and holding portion SU may also be formed with a polygonal shape of octagon or more on its inner surface. [Explanation of Symbols]

[0063] 11 Lens Unit 12 Telescope Tubes 13, 14, 15, 16, 17 Lenses 30 Spacers 50 FPC heaters (surface heaters) 51 Heating section 52 Extension 60 PTC heaters (surface heaters) 55,30d Through groove (through section) 56 Outlet hole L lens group O optical axis

Claims

1. In a lens unit comprising a plurality of lenses arranged along the optical axis, a lens barrel that houses and holds these plurality of lenses, and a planar heater capable of heating the first lens located closest to the object, The planar heater includes a heating section for heating the first lens, The heating element is bonded to the image-side end face of the first lens with an adhesive. The first lens and the second lens or spacer are adjacent to each other in the optical axis direction and are in contact with each other on their outer periphery. A lens unit characterized in that a recess for accommodating the heating element bonded to the first lens is provided on the inner circumference side of the second lens or the spacer.

2. The lens unit according to claim 1, characterized in that the planar heater is an FPC heater or an organic PTC heater.

3. The aforementioned planar heater is an organic PTC heater, The lens unit according to claim 1, characterized in that a gap is provided between a second lens or spacer adjacent to the first lens in the optical axis direction and the heating portion of the organic PTC heater.

4. The planar heater includes a strip-shaped extension that extends from the heating section and supplies electricity to the heating section, An insertion portion is provided on the outer circumference of a second lens or spacer adjacent to the first lens in the optical axis direction, allowing the extension of the planar heater to be inserted along the axial direction of the lens barrel. The lens unit according to any one of claims 1 to 3, characterized in that the lens barrel is provided with an outlet hole in communication with the insertion portion for leading out the extension portion inserted into the insertion portion to the outside.

5. The lens unit according to any one of claims 1 to 4, characterized in that the adhesive is a thermosetting adhesive.

6. A camera module characterized by comprising a lens unit according to any one of claims 1 to 5.

Images