Lens unit and camera module

Abstract

To suppress the deterioration of optical performance and suitably heat a lens.SOLUTION: A lens unit 1 comprises: an imaging optical system 2 including a first lens 21 and a second lens 22 in order from an object side; a spacer 4 sandwiched between an image side plane 21b of the first lens 21 and an object side plane 22a of the second lens 22; and a heating portion 51 that abuts on the spacer 4 and heats the image side plane 21b of the first lens 21.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a lens unit and a camera module. [Background technology]

[0002] In recent years, cameras have been used for various purposes, and cameras for outdoor use, such as surveillance cameras and in-vehicle cameras, are on the rise. In this type of camera, the lens surface freezes or ice and snow adhere to it during low temperatures in winter or snowfall. In such cases, the captured image may become unclear due to the adhesions on the lens surface, and the lens may not be able to perform its intended function. Therefore, there is a demand for the development of a lens unit with a defrosting or snow melting function.

[0003] In the lens unit described in Patent Document 1, the heating part of a planar heater is attached to the image-side end face of the first lens located closest to the object, and ice and snow adhering to the surface of the first lens are melted. Heating the first lens also serves as a measure against condensation and fogging on the image side of the first lens. The heating part is sandwiched between the first lens and the second lens or the spacer, and is housed in the lens barrel. However, with this structure, when the tip of the lens barrel is plastically deformed and crimped after each component is assembled inside the lens barrel, pressure is applied to the heating section via the first lens. If the heating section is an FPC (Flexible Printed Circuits) heater, the wiring width is narrow to increase the resistance value, so this pressure may cause disconnection or change in resistance value. Also, if the heating section has a layered structure such as a PTC (Positive Temperature Coefficient) heater, there is variation in the thickness of the heating section. Variation in the thickness of the heating section leads to variation in the axial position of the lens, which may lead to deterioration of optical performance. In other words, a structure in which the heating portion is sandwiched between the lens to be heated and the adjacent parts is not desirable.

[0004] In this regard, in the lens unit described in Patent Document 2, a gap (space) for disposing the heating part is secured between the optical parts by using protrusions or spacers provided on the optical parts that sandwich the heating part. The width of the gap is set to be equal to or slightly larger than the thickness of the heating part, thereby mitigating the pressure that the heating part receives from the optical parts. However, as mentioned above, there is variation (individual differences) in the thickness of the heating portion. Therefore, if the heating portion is thicker than the gap, the distance between the optical components cannot be maintained. On the other hand, if the heating portion is thinner than the gap, the heating portion cannot be brought into reliable contact with the first lens, and there is a risk that the first lens cannot be heated well. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2022-34211 A [Patent Document 2] JP 2023-25373 A Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made in consideration of the above circumstances, and has an object to suppress deterioration of optical performance and to heat a lens in a suitable manner. [Means for solving the problem]

[0007] In order to achieve the above object, the present invention provides a lens unit, comprising: an optical system including, in order from the object side, a first lens and a second lens; a spacer sandwiched between an image side surface of the first lens and an object side surface of the second lens; a heating section that contacts the spacer and heats the image side surface of the first lens; Equipped with. Effect of the Invention

[0008] According to the present invention, it is possible to suppress deterioration of optical performance and to heat the lens appropriately. [Brief description of the drawings]

[0009] [Figure 1] 1A and 1B are a perspective view and a cross-sectional view of a camera module according to an embodiment of the present invention. [Diagram 2] 1A and 1B are a perspective view and a cross-sectional view of a lens unit according to an embodiment of the present invention. [Diagram 3] FIG. 2(b) is an enlarged view of part A in FIG. [Figure 4] FIG. 2 is a perspective view of a heater according to the embodiment. [Diagram 5] FIG. 11 is a cross-sectional view of a lens unit according to a modified example of the embodiment. [Figure 6] 13A and 13B are diagrams for explaining a fixing structure of a heating unit according to a modified example of the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0011] [Overall camera module configuration] 1(a) and 1(b) are a perspective view and a cross-sectional view of a camera module 100 according to this embodiment. As shown in FIGS. 1(a) and 1(b), the camera module 100 includes a lens unit 1, a camera case 102, and an imaging element 104. The camera case 102 houses the lens unit 1 with the first lens 21 of the lens unit 1 exposed to the front.

[0012] The imaging element 104 is a solid-state imaging element that detects and photoelectrically converts an object image formed by the imaging optical system 2 of the lens unit 1. For example, the imaging element 104 is an image sensor of a CMOS type or a CCD type. The imaging element 104 is fixed to a sensor holder 106 in a state where it is mounted on an imaging element substrate 105. The sensor holder 106 is fixed to the lens barrel 3 of the lens unit 1 in a state where the imaging element 104 is positioned with respect to the imaging optical system 2 of the lens unit 1.

[0013] [Overall lens unit configuration] 2(a) and (b) are a perspective view and a cross-sectional view of the lens unit 1, and FIG. 3 is an enlarged view of part A in FIG. 2(b). In the following, the direction along the optical axis Ax of the lens unit 1 (imaging optical system 2) is referred to as the "axial direction", the direction perpendicular to the axial direction is referred to as the "radial direction", and the rotation direction around the optical axis Ax is referred to as the "circumferential direction". As shown in FIGS. 2(a) and 2(b), the lens unit 1 includes an imaging optical system 2 and a lens barrel (lens barrel) 3.

[0014] The imaging optical system 2 is a single-focus optical system that forms a subject image on the imaging surface (projection surface) of the image sensor 104, and includes a plurality of lenses 20. The multiple lenses 20 include, in order from the object side (the left side in FIG. 2(b)), a first lens 21 to an eighth lens 28. However, it is sufficient that the imaging optical system 2 includes at least the first lens 21 and the second lens 22.

[0015] Of the multiple lenses 20, the first lens 21 located closest to the object has its object side surface 21a exposed to the outside. The first lens 21 is fixed to the object side end of the lens barrel 3 by a lens presser 61. The gap between the outer circumferential surface of the first lens 21 and the inner circumferential surface of the lens barrel 3 is sealed by an O-ring 62. The surface of the first lens 21 on the image side (the right side in FIG. 2(b)) excluding the optical surface is painted black to block light.

[0016] The material (material) of each lens 20 is not particularly limited, but all of them are glass. The first lens 21 exposed to the outside is made of a glass lens because it is required to be scratch-resistant, abrasion-resistant, chemical-resistant, etc. The second lens 22 and subsequent lenses 20 may be made of plastic lenses to reduce costs, etc.

[0017] The lens barrel 3 is formed in a substantially cylindrical shape and houses therein a plurality of lenses 20 and a holding member 29 for holding the lenses 20. The lens barrel 3 is made of, for example, a material such as resin, metal, or a mixture of resin and glass fiber.

[0018] [Lens heating structure] The lens unit 1 includes a heater 5 for heating the first lens 21 to melt ice or snow on the object side surface 21a. The heater 5 indirectly heats the first lens 21 via the spacer 4.

[0019] As shown in FIG. 3, the spacer 4 is formed in a substantially circular plate shape and is disposed on the image side of the first lens 21. The spacer 4 is sandwiched between an image side end face (image side plane) 21b of the first lens 21 and an object side end face (object side plane) 22a of the second lens 22. The image side plane 21b of the first lens 21 and the object side plane 22a of the second lens 22 are both formed in a flat surface shape substantially perpendicular to the optical axis Ax and face each other in the axial direction. When the spacer 4 is sandwiched between the first lens 21 and the second lens 22, the object side surface 4a abuts (contacts) the image side plane 21b of the first lens 21 over substantially the entire surface. The outer diameter portion of the spacer 4 defines a part of a groove for accommodating an O-ring 62. The spacer 4 may have any shape as long as it can heat the first lens 21 satisfactorily, and may be, for example, a horseshoe shape.

[0020] The spacer 4 has a spigot 41 on its inner diameter portion on the image side that fits into the second lens 22. The spigot 41 is formed in a stepped shape that is positioned gradually toward the image side toward the outer diameter side, and its inner peripheral surface is formed to a predetermined fitting dimension with the outer peripheral surface 22b of the second lens 22. The spacer 4 is positioned relative to the second lens 22 in the radial direction by fitting the spigot 41 into the outer peripheral surface 22b of the second lens 22. The fitting dimensions of the spigot 41 are formed so that the radial gap between the second lens 22 and the lens barrel 3 at the outer diameter portion is smaller than the radial gap CL1 between the lens barrel 3 and the outer diameter portion. The radial gap CL1 is a radial clearance between the outer peripheral surface 4c of the spacer 4 and the first inner peripheral surface 31a of the lens barrel 3 at the portion that houses the spacer 4. This allows the radial position of the spacer 4 to be positioned so as not to come into contact with the lens barrel 3. The second lens 22 is positioned radially with respect to the lens barrel 3 by fitting the outer peripheral surface into the second inner peripheral surface 32a of the lens barrel 3.

[0021] The spacer 4 is disposed on the outer diameter side of the photographing optical path of the lens unit 1. More specifically, the inner diameter of the spacer 4 is formed to have a dimension that does not position it in the photographing optical path even when it moves radially within the range of the radial gap of the spigot 41. Therefore, the spacer 4 does not affect the optical performance of the lens unit 1 regardless of the assembled state. However, the spacer 4 (its inner diameter) may function as a diaphragm for restricting the light beam.

[0022] The material of the spacer 4 is not particularly limited, but is preferably a metal having good thermal conductivity, and in this embodiment is an aluminum alloy or a copper alloy. The thermal conductivity of the spacer 4 is preferably at least 50 W / (m K).

[0023] 4(a) and (b) are perspective views of the heater 5. As shown in FIG. 3 and FIGS. 4(a) and (b), the heater 5 has a heating section 51 that generates heat and a power supply section 52 that supplies power to the heating section 51.

[0024] The heating portion 51 is formed in a thin annular shape, and is adhered to the image side surface 4b of the spacer 4, which is on the outer diameter side of the spigot 41, by an adhesive layer 54. The adhesive layer 54 is a thermally conductive double-sided tape or adhesive, and adheres the heating portion 51 to the spacer 4 over substantially the entire surface in a manner allowing heat to be transferred thereto. The axial position of the heating portion 51 is off to the image side from the axial range P between the image side plane 21b of the first lens 21 and the object side plane 22a of the second lens 22, which sandwich the spacer 4. A thermistor 53 for measuring temperature is attached to the image side of the heating unit 51. Temperature information acquired by the thermistor 53 is output to a power supply board 55 or other heating unit power supply control unit on the camera side. The shape of the heating part 51 is not limited to annular, and may be, for example, a horseshoe shape, as long as it can satisfactorily heat the first lens 21. The axial position of the heating part 51 is only required to be out of the space between the image-side plane 21b of the first lens 21 and the object-side plane 22a of the second lens 22, and may be out of the space toward the object side or out of the outer diameter side.

[0025] The power supply unit 52 is formed in a long strip shape extending from a part of the circumferential direction of the heating unit 51, and is drawn out to the outside of the lens barrel 3 through the hole 33 of the lens barrel 3. The hole 33 is a through hole that communicates the inside and outside of the lens barrel 3, and opens on the outer circumferential surface of the lens barrel 3. After the imaging optical system 2 and the heater 5 are incorporated into the lens barrel 3 and the power supply unit 52 is inserted, the hole 33 is closed with a sealing material such as a resin material, adhesive, or elastic material (not shown). This makes it possible to prevent dust from entering through the hole 33. In addition, since the power supply unit 52 is directly fixed to the lens barrel 3, even if the power supply unit 52 is pulled from the outside, the force is not easily transmitted to the heating unit 51. Therefore, for example, it is possible to avoid a situation in which the heating unit 51 is peeled off from the spacer 4 during assembly work. The tip of the power supply unit 52 is connected to a power supply board 55 fixed to the sensor holder 106 (see FIG. 1(b)). The power supply board 55 controls the power supply to the heating unit 51 based on temperature information of the heating unit 51 acquired from, for example, the thermistor 53. The power supply board 55 may be configured integrally with the imaging element board 105.

[0026] The heater 5 (heating unit 51) in this embodiment is an FPC (Flexible printed circuits) heater, which generates heat when electricity is applied to stainless steel or copper foil. However, the heater (heating unit) applicable to the lens unit 1 is not limited to the FPC heater, and may be any heater that can be formed into a thin plane. Examples of such plane heaters include a PTC heater, a carbon nanotube (CNT) film heater, and a heater using a Peltier element. PTC heaters are made by combining semiconductor particles and carbon particles (conductors) that conduct electricity well, and have PTC (Positive Temperature Coefficient) characteristics. PTC characteristics are a property in which electrical resistance changes with a positive coefficient as temperature rises, meaning that electricity flows easily when the temperature is low, and becomes more difficult to flow as the temperature rises. Therefore, power consumption can be reduced when the temperature is stable at a high value. A CNT heater is a highly flexible, thin, planar heater that uses carbon nanotubes as a resistor. Compared to hot wire heaters, a CNT heater can generate heat more uniformly over the entire surface. Heaters using Peltier elements use a Peltier element that can adjust the temperature by controlling the current passing through it. This heater can not only heat the lens but also cool it. In addition, in the case of an FPC heater, the heating section 51 and the power supply section 52 are integrally connected by wiring patterns, but in the other planar heaters mentioned above, the heating section 51 and the power supply section 52 are separate elements. Therefore, it is necessary to electrically connect the heating section 51 and the power supply section 52 by, for example, soldering, a conductive adhesive, crimping, welding, etc.

[0027] It should be noted that the heater 5 (heating portion 51) and the spacer 4 need only be in contact with each other so as to be capable of transferring heat therebetween, and the manner of contact does not have to be by "adhesion." For example, as shown in FIG. 5 and FIG. 6(a)-(d), the heating unit 51 may be sandwiched between the spacer 4 and the fixing member 7 in the axial direction. The fixing member 7 is made of a material having a lower thermal conductivity than the spacer 4 so as to make it difficult to remove heat from the heating unit 51. Specifically, in this case, a plurality of bosses 43 are provided on the image side surface 4b of the spacer 4 (FIG. 6(a)). The heating unit 51 has a plurality of holes 51a corresponding to the plurality of bosses 43, and is disposed on the image side of the spacer 4 with the plurality of bosses 43 penetrating the plurality of holes 51a (FIG. 6(b)). The fixing member 7 is formed in a disk shape corresponding to the heating unit 51, and has a plurality of holes 71a corresponding to the plurality of bosses 43. The fixing member 7 is disposed on the image side of the heating unit 51 with the plurality of bosses 43 penetrating the plurality of holes 71a (FIG. 6(c)). Then, the tip of the boss 43 exposed from the hole 71a is fixed to the fixing member 7 by, for example, an adhesive 73 (FIG. 6(d)). This allows the heating portion 51 to be clamped and fixed in the axial direction between the spacer 4 and the fixing member 7. However, the structure for fixing the spacer 4 and the fixing member 7 is not limited to the boss. For example, instead of the boss 43 or the holes 51a and 71a, a notch may be provided in a part of the outer diameter part of the heating part 51, and the spacer 4 and the fixing member 7 may be bonded through the notch. A structure in which a locking claw is provided on either the spacer 4 or the fixing member 7 to make them detachable (for example, a snap fastener) may also be used.

[0028] [Technical effect of the present embodiment] As described above, according to this embodiment, the heating portion 51 of the heater 5 contacts the spacer 4 to heat the image-side flat surface 21b of the first lens 21. Therefore, unlike a structure in which the first lens 21 and the second lens 22 directly sandwich the heating portion 51, the heating portion 51 is not subjected to pressure associated with sandwiching. In addition, by using a material with good thermal conductivity for the spacer 4, more uniform heating of the image-side flat surface 21b of the first lens 21 can be expected. Moreover, the spacer 4 is sandwiched between the image-side flat surface 21b of the first lens 21 and the object-side flat surface 22a of the second lens 22. Therefore, unlike a structure in which the first lens 21 and the second lens 22 sandwich the heating portion 51, the axial position of each lens 20 does not vary depending on the thickness of the heating portion 51. Therefore, it is possible to suppress deterioration in optical performance and to heat the first lens 21 in an appropriate manner. Furthermore, since the structure in which the heating unit 51 is directly bonded to the first lens 21 can be avoided, the second lens 22 can be suitably formed. That is, when the heating unit is directly bonded to the first lens, in order to avoid interference between the adhesive and the second lens, if the second lens 22 is a glass lens, the centering shape becomes complicated, resulting in an increase in the number of steps, and in the case of a plastic lens, it is necessary to provide a large concave shape in the flange portion, which may affect the moldability and thus the surface accuracy of the optical surface. By avoiding the structure in which the heating unit 51 is directly bonded to the first lens 21, such a situation can be avoided. Furthermore, since the image-side flat surface 21b of the first lens 21 is a surface having concaves and convexes due to the black coating, bonding to such a surface is undesirable in terms of heat transfer and workability.

[0029] According to this embodiment, the spacer 4 is positioned relative to the second lens 22 in the radial direction by the spigot 41. The radial gap between the spigot 41 and the second lens 22 is smaller than the radial gap CL1 between the spigot 41 and the first inner circumferential surface 31a of the barrel 3. This allows the spacer 4 to be positioned so that the spacer 4 does not come into contact with the lens barrel 3. This prevents the heat of the heating unit 51 transferred to the spacer 4 from being taken by the lens barrel 3. As a result, the first lens 21 can be heated appropriately.

[0030] Furthermore, according to this embodiment, the spacer 4 is disposed on the outer diameter side of the lens unit 1 relative to the photographing optical path. Therefore, the spacer 4 does not affect the optical performance of the lens unit 1 regardless of the assembled state.

[0031] Furthermore, according to this embodiment, the heating unit 51 is adhered to the image side surface 4b of the spacer 4 by the adhesive layer 54, which is a thermally conductive double-sided tape or adhesive. This allows the heat from the heating portion 51 to be suitably transferred to the spacer 4 .

[0032] Furthermore, according to this embodiment, the heating portion 51 may be sandwiched in the axial direction by a fixing member 7 having a lower thermal conductivity than the spacer 4. According to this structure, the heating portion 51 and the spacer 4 can be suitably brought into contact with each other without bonding the heating portion 51 to the spacer 4 .

[0033] Furthermore, according to this embodiment, the heating unit 51 is provided with a thermistor 53 . This makes it possible to detect the temperature of the heating unit 51 more accurately, and to suitably control the temperature of the first lens 21.

[0034] [others] Although one embodiment of the present invention has been described above, embodiments to which the present invention can be applied are not limited to the above-described embodiment and its variations, and can be modified as appropriate without departing from the spirit of the present invention.

[0035] For example, in the above embodiment, the first lens is heated in order to melt the frozen or ice / snow on the surface, but the first lens may be heated for other purposes, such as to remove fogging from the first lens. [Explanation of symbols]

[0036] 1 Lens unit 2 Imaging optical system (optical system) 20 Lenses 21 First lens 21a Object side 21b Image side plane (image side) 22 Second lens 22a Object side plane (object side) 22b Outer surface 3. Telescope tube 31a 1st inner surface 32a 2nd inner surface 33 Hole 4 Spacer 4a Object side 4b Image side 4c Outer surface 41 Inlay 43 Boss 5 Heater 51 Heating section 51a Hole 52 Power supply unit 53 Thermistor 54 Adhesive layer 55 Power supply board 7 Fixing member 100 Camera Module 104 Image sensor Ax optical axis CL1 Radial clearance P Axial Range

Claims

1. an optical system including, in order from the object side, a first lens and a second lens; a spacer sandwiched between an image side surface of the first lens and an object side surface of the second lens; a heating section that contacts the spacer and heats the image side surface of the first lens; A lens unit comprising:

2. an axial position of the heating unit is out of a position between an image side surface of the first lens and an object side surface of the second lens, the image side surface and the object side surface of the second lens sandwiching the spacer therebetween; The lens unit according to claim 1 .

3. the heating portion is in contact with an image side surface of the spacer; The lens unit according to claim 2 .

4. a lens barrel that houses the optical system and the spacer, The spacer is A spigot is provided between the first lens and the second lens for radially positioning the first lens and the second lens, a radial gap between the first lens or the second lens at the spigot joint is smaller than a radial gap between the spigot joint and an inner circumferential surface of the lens barrel; The lens unit according to claim 1 .

5. The spacer is disposed on the outer diameter side of the imaging optical path. The lens unit according to claim 1 .

6. the heating unit is attached to the image side of the spacer by a thermally conductive double-sided tape or adhesive; The lens unit according to claim 1 .

7. The thermal conductivity of the spacer is 50 W / (m·K) or more. The lens unit according to claim 1 .

8. The heating portion is axially sandwiched by a fixing member having a lower thermal conductivity than the spacer. The lens unit according to claim 1 .

9. A thermistor is disposed in the heating section. The lens unit according to claim 1 .

10. The heating portion is formed in an annular or horseshoe shape. The lens unit according to claim 1 .

11. The heating unit is an FPC heater. The lens unit according to claim 1 .

12. A lens unit according to any one of claims 1 to 11, an image sensor that photoelectrically converts an object image formed by the optical system; A camera module comprising:

Images