Lens unit and camera module

Abstract

The invention provides a lens unit and a camera module, which can suppress reduction of optical performance and properly heat a lens. A lens unit (1) is provided with: an imaging optical system (2) including a first lens (21) and a second lens (22) in this order from the object side; a spacer (4) sandwiched between the image-side plane (21b) of the first lens (21) and the object-side plane (22a) of the second lens (22); and a heating unit (51) that is in contact with the spacer (4) and heats the image-side plane (21b) of the first lens (21).

Description

Technical Field

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

[0002] In recent years, cameras are used for various purposes, and the number of cameras used outdoors, such as surveillance cameras and car-mounted cameras, has been increasing. In such cameras, the lens surface may freeze or be attached with ice and snow in the low temperature of winter or when snow falls. In such cases, there is a concern that the image captured may become unclear due to the attachments on the lens surface, and the original function may not be exerted. Therefore, the development of lens units with thawing and snow melting functions is required.

[0003] In the lens unit described in Patent Document 1, a heating portion of a planar heater is bonded to the image side end surface of the first lens located closest to the object side, so that ice and snow attached to the surface of the first lens are melted. Heating the first lens also serves as a countermeasure for condensation and fogging on the image side surface of the first lens. The heating portion is sandwiched between the first lens and the second lens or the spacer and is housed in the lens barrel.

[0004] However, in this structure, after assembling each component into the lens barrel (lens body), the front end of the lens barrel is plastically deformed for riveting and fixing, and pressure is applied to the heating part through the first lens. In the case where the heating part is an FPC (Flexible printed circuits) heater, the wiring width is made thinner for the purpose of increasing the resistance value, so there is a concern that the wire may be broken or the resistance value may change due to this pressure. In addition, in the case where the heating part is a stacked structure like a PTC (Positive Temperature Coefficient) heater, there is a deviation in the thickness of the heating part. The deviation in the thickness of the heating part leads to a deviation in the axial position of the lens, which may lead to a deterioration in the optical performance.

[0005] That is, a structure in which the heating unit is sandwiched between the lens to be heated and the adjacent member is not preferable.

[0006] In this regard, in the lens unit described in Patent Document 2, a gap (space) for arranging the heating unit is ensured between the optical components by providing a protrusion or a spacer on the optical component sandwiching the heating unit. The width of the gap is set to be equal to or slightly thicker than the thickness of the heating unit, thereby alleviating the pressure on the heating unit from the optical component.

[0007] However, as described above, there are variations in the thickness of the heating portion (individual differences). Therefore, when the heating portion is thicker than the gap, the interval between the optical components cannot be maintained. On the other hand, when the heating portion is thinner than the gap, there is a concern that the heating portion cannot be reliably contacted with the first lens, and the first lens cannot be heated well.

[0008] Patent Document 1: Japanese Patent Application Publication No. 2022-34211

[0009] Patent Document 2: Japanese Patent Application Publication No. 2023-25373 Summary of the invention

[0010] The present invention has been made in view of the above circumstances, and an object of the present invention is to appropriately heat a lens while suppressing a decrease in optical performance.

[0011] In order to achieve the above object, the present invention provides a lens unit, which comprises:

[0012] An optical system including, from the object side, a first lens and a second lens;

[0013] a spacer sandwiched between the image-side surface of the first lens and the object-side surface of the second lens; and

[0014] The heating unit is in contact with the spacer to heat the image side surface of the first lens.

[0015] According to the present invention, it is possible to appropriately heat the lens while suppressing a decrease in optical performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 (a) is a perspective view and (b) is a cross-sectional view of a camera module according to an embodiment.

[0017] Figure 2 (a) is a perspective view and (b) is a cross-sectional view of a lens unit according to an embodiment.

[0018] Figure 3 yes Figure 2 (b) An enlarged view of part A.

[0019] Figure 4 It is a perspective view of the heater according to the embodiment.

[0020] Figure 5 It is a cross-sectional view of a lens unit according to a modification of the embodiment.

[0021] Figure 6 It is a diagram for explaining a fixing structure of a heating unit according to a modified example of the embodiment.

[0022] Explanation of the reference numerals: 1…lens unit; 2…shooting optical system (optical system); 20…lens; 21…first lens; 21a…object side surface; 21b…image side plane (image side surface); 22…second lens; 22a…object side plane (object side surface); 22b…outer peripheral surface; 3…lens barrel; 31a…first inner peripheral surface; 32a…second inner peripheral surface; 33…hole portion; 4…spacer; 4a…object side surface; 4b…image side surface; 4c…outer peripheral surface; 41…socket; 43…boss; 5…heater; 51…heating portion; 51a…hole portion; 52…power supply portion; 53…thermistor; 54…adhesive layer; 55…power supply substrate; 7…fixing component; 100…camera module; 104…shooting element; Ax…optical axis; CL1…radial gap; P…axial range. DETAILED DESCRIPTION

[0023] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0024] [Overall structure of the camera module]

[0025] Figure 1 (a) and (b) are a perspective view and a cross-sectional view of the camera module 100 according to the present embodiment.

[0026] like Figure 1 As shown in (a) and (b) of FIG. 1 , the camera module 100 includes a lens unit 1 , a camera housing 102 , and an imaging element 104 .

[0027] The camera housing 102 accommodates the lens unit 1 in a state where the first lens 21 of the lens unit 1 is exposed to the front.

[0028] The imaging element 104 is a solid-state imaging element that detects and photoelectrically converts a subject 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, a CCD type, or the like.

[0029] The imaging element 104 is fixed to the sensor holder 106 while being mounted on the imaging element substrate 105. The sensor holder 106 is fixed to the lens barrel 3 of the lens unit 1 while positioning the imaging element 104 relative to the imaging optical system 2 of the lens unit 1.

[0030] [Overall structure of the lens unit]

[0031] Figure 2 (a) and (b) are a perspective view and a cross-sectional view of the lens unit 1. Figure 3 yes Figure 2 (b) An enlarged view of part A.

[0032] Hereinafter, the direction along the optical axis Ax of the lens unit 1 (photographing 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 direction rotating around the optical axis Ax is referred to as the “circumferential direction”.

[0033] like Figure 2 As shown in (a) and (b) of FIG. 8 , the lens unit 1 includes a photographing optical system 2 and a lens barrel (lens barrel) 3 .

[0034] The imaging optical system 2 is a single-focus optical system that forms an image of a subject on an imaging surface (projection surface) of the imaging element 104 , and includes a plurality of lenses 20 .

[0035] A plurality of lenses 20 are provided from the object side ( Figure 2 The photographing optical system 2 includes, in order from the left side of (b), the first lens 21 to the eighth lens 28. However, the photographing optical system 2 only needs to include at least the first lens 21 and the second lens 22.

[0036] The first lens 21 located closest to the object side among the plurality of lenses 20 has its object side surface 21a exposed to the outside. The first lens 21 is fixed to the end of the object side of the lens barrel 3 by a lens pressing member 61. The outer peripheral surface of the first lens 21 and the inner peripheral surface of the lens barrel 3 are sealed by an O-ring 62. The image side ( Figure 2 The right side of (b) is painted with ink for light shielding.

[0037] The material of each lens 20 is not particularly limited, but all are glass. The first lens 21 exposed to the outside is a glass lens because it is required to be scratch-resistant, wear-resistant, and chemical-resistant. In order to reduce costs, the lenses 20 after the second lens 22 can also be plastic lenses.

[0038] The lens barrel 3 is formed in a substantially cylindrical shape, and accommodates a plurality of lenses 20 and a holding member 29 for holding the lenses 20. The lens barrel 3 is made of, for example, resin, metal, or a material obtained by mixing glass fiber in resin.

[0039] [Lens heating structure]

[0040] The lens unit 1 includes a heater 5 for heating the first lens 21 to melt frozen ice or snow on the object-side surface 21 a. The heater 5 indirectly heats the first lens 21 via the spacer 4 .

[0041] like Figure 3As shown, the spacer 4 is formed into a roughly circular plate shape and is arranged on the image side of the first lens 21. The spacer 4 is clamped between the end face (image side plane) 21b on the image side of the first lens 21 and the end face (object side plane) 22a on the object side 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 into flat surfaces that are roughly perpendicular to the optical axis Ax and are opposite to each other in the axial direction. When the spacer 4 is clamped by the first lens 21 and the second lens 22, the object side surface 4a abuts (contacts) with the image side plane 21b of the first lens 21 over substantially the entire surface. The outer diameter portion of the spacer 4 divides a portion of the groove for accommodating the O-ring 62.

[0042] The spacer 4 may have any shape that can satisfactorily heat the first lens 21 , and may have a horseshoe shape, for example.

[0043] The spacer 4 has a socket 41 on the inner diameter portion on the image side that is engaged with the second lens 22. The socket 41 is formed in a stepped shape that is gradually located on the image side toward the outer diameter side, and its inner peripheral surface is formed to a predetermined engagement dimension with respect to the outer peripheral surface 22b of the second lens 22. By engaging the socket 41 with the outer peripheral surface 22b of the second lens 22, the spacer 4 and the second lens 22 are positioned relative to each other in the radial direction.

[0044] The fitting size of the socket 41 is formed so that the radial gap between the socket 41 and the second lens 22 is smaller than the radial gap CL1 between the outer diameter portion and the lens barrel 3. The radial gap CL1 is a radial gap between the outer peripheral surface 4c of the spacer 4 and the first inner peripheral surface 31a of the lens barrel 3 in the portion where the spacer 4 is stored. Thus, the radial position of the spacer 4 can be positioned so as not to contact the lens barrel 3. In addition, by fitting the outer peripheral surface of the second lens 22 with the second inner peripheral surface 32a of the lens barrel 3, the second lens 22 is positioned radially relative to the lens barrel 3.

[0045] The spacer 4 is arranged at a position closer to the outer diameter side than the photographing optical path of the lens unit 1. More specifically, the inner diameter of the spacer 4 is formed to a size such that it will not be located in the photographing optical path even when it moves radially within the range of the radial clearance of the socket 41. Therefore, the spacer 4 will not affect the optical performance of the lens unit 1 regardless of the assembly state.

[0046] However, (the inner diameter of) the spacer 4 may also function as an aperture for limiting light.

[0047] The material of the spacer 4 is not particularly limited, but is preferably a metal having good thermal conductivity, and in this embodiment, an aluminum alloy or a copper alloy. The thermal conductivity of the spacer 4 is preferably at least 50 W / (m·K).

[0048] Figure 4(a) and (b) are perspective views of the heater 5.

[0049] like Figure 3 as well as Figure 4 As shown in (a) and (b) of FIG. 1 , the heater 5 includes a heating portion 51 for generating heat and a power supply portion 52 for supplying power to the heating portion 51 .

[0050] The heating portion 51 is formed in a thin annular shape and is bonded to the image side surface 4b on the outer diameter side of the socket 41 of the image side surface of the spacer 4 through an adhesive layer 54. The adhesive layer 54 is a double-sided tape or adhesive having thermal conductivity, and the heating portion 51 is bonded to the spacer 4 in a thermally conductive manner over the substantially entire surface. The axial position of the heating portion 51 is deviated toward 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 that clamp the spacer 4.

[0051] A thermistor 53 for measuring temperature is mounted on the image side of the heating unit 51. Temperature information acquired by the thermistor 53 is output to a heating unit power supply control unit on the camera side such as a power supply substrate 55.

[0052] In addition, the shape of the heating portion 51 is not limited to an annular shape, and any shape can be used as long as it can well heat the first lens 21, for example, it can also be a horseshoe shape, etc. In addition, the axial position of the heating portion 51 can be deviated from 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 can be deviated from the space to the object side or to the outer diameter side.

[0053] The power supply unit 52 is formed into a strip-like shape extending from a part of the circumference of the heating unit 51, and is led 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 is opened on the outer peripheral surface of the lens barrel 3. After the lens barrel 3 is installed with the shooting optical system 2 and the heater 5 and the power supply unit 52 is inserted, the hole 33 is blocked by sealing components such as resin materials, adhesives, elastic materials, etc. that are not shown. Thus, it is possible to prevent dust from invading from the hole 33. In addition, the power supply unit 52 is directly fixed to the lens barrel 3, so even when 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 the situation where the heating unit 51 is peeled off from the spacer 4 during the assembly operation.

[0054] The front end of the power supply unit 52 is connected to a power supply substrate 55 fixed to the sensor holder 106 (see Figure 1 (b)). The power supply substrate 55 controls the power supply to the heating section 51 based on, for example, the temperature information of the heating section 51 acquired from the thermistor 53. In addition, the power supply substrate 55 may be formed integrally with the imaging element substrate 105.

[0055] The heater 5 (heating unit 51 ) of the present embodiment is an FPC (Flexible printed circuits) heater, and generates heat by passing electricity through stainless steel or copper foil.

[0056] However, the heater (heating unit) applicable to the lens unit 1 is not limited to the FPC heater, and any heater that can be formed into a thin planar shape is acceptable. Examples of such a planar heater include a PTC heater, a carbon nanotube (CNT) thin film heater, and a heater using a Peltier element.

[0057] The PTC heater is made by combining semiconductor particles with carbon particles (conductors) that transmit electricity well, and has PTC (Positive Temperature Coefficient) characteristics. The PTC characteristic is the property that the resistance value changes with a positive coefficient as the temperature rises. When the temperature is low, electricity flows easily, but as the temperature rises, electricity does not flow easily. Therefore, if the temperature is stabilized at a high value, the power consumption can be suppressed.

[0058] CNT heaters are thin, highly flexible planar heaters that use carbon nanotubes as resistors. CNT heaters can generate heat more evenly over the entire surface than hot wire heaters.

[0059] In the heater using the Peltier element, the Peltier element whose temperature can be adjusted by power supply control is used. In the case of this heater, not only the lens can be heated but also cooled.

[0060] In the case of the FPC heater, the wiring patterns are integrally connected in the heating portion 51 and the power supply portion 52, but in the other planar heaters described above, the heating portion 51 and the power supply portion 52 are different elements. Therefore, the heating portion 51 and the power supply portion 52 need to be connected so that electricity can flow therethrough, for example, by solder, conductive adhesive, crimping, welding, etc.

[0061] Furthermore, as long as the heater 5 (heating portion 51 ) and the spacer 4 can be in thermally conductive contact, the contact method may not be “adhesion”.

[0062] For example, you can also Figure 5 as well as Figure 6 As shown in (a) to (d) of FIG. 1 , the spacer 4 and the fixing member 7 sandwich the heating portion 51 in the axial direction. The fixing member 7 is made of a material with a lower thermal conductivity than the spacer 4 so that it is not easy to take away the heat of the heating portion 51. Specifically, in this case, a plurality of bosses 43 ( Figure 6The heating unit 51 has a plurality of holes 51a corresponding to the plurality of bosses 43, and is arranged on the image side of the spacer 4 while allowing the plurality of bosses 43 to pass through the plurality of holes 51a ( Figure 6 (b)). The fixing member 7 is formed into 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 arranged on the image side of the heating unit 51 while allowing the plurality of bosses 43 to pass through the plurality of holes 71a. Figure 6 (c)). Then, the front end of the boss 43 exposed from the hole 71a is fixed to the fixing member 7 by, for example, an adhesive 73 ( Figure 6 (d)). Thus, the heating unit 51 can be clamped and fixed in the axial direction by the spacer 4 and the fixing member 7.

[0063] However, the structure for fixing the spacer 4 and the fixing member 7 is not limited to the structure based on the boss. For example, a notch may be provided in a part of the outer diameter portion of the heating portion 51 instead of the boss 43, the hole portion 51a, and 71a, 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 so that they can be attached and detached (for example, hook engagement, etc.) is also possible.

[0064] [Technical Effects of the Present Embodiment]

[0065] As described above, according to the present embodiment, the heating portion 51 of the heater 5 abuts against the spacer 4 to heat the image side plane 21b of the first lens 21. Therefore, unlike the 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 the pressure associated with the sandwiching. In addition, by using a material with good thermal conductivity for the spacer 4, it can be expected that the image side plane 21b of the first lens 21 can be heated more uniformly.

[0066] In addition, the spacer 4 is sandwiched between the image side plane 21b of the first lens 21 and the object side plane 22a of the second lens 22. Therefore, unlike the 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 deviate due to the thickness of the heating portion 51.

[0067] Therefore, it is possible to appropriately heat the first lens 21 while suppressing a decrease in optical performance.

[0068] Furthermore, since the structure of directly bonding the heating part 51 to the first lens 21 is avoided, the second lens 22 can be properly formed. That is, in the case of directly bonding the heating part to the first lens, in order to avoid interference between the adhesive and the second lens, when the second lens 22 is a glass lens, the centering shape becomes complicated, thereby increasing the working hours, and when the second lens 22 is a plastic lens, since a larger concave shape needs to be provided in the flange portion, the moldability is affected, thereby also affecting the surface accuracy of the optical surface. By avoiding the structure of directly bonding the heating part 51 to the first lens 21, such a situation can be avoided. In addition, the image side plane 21b of the first lens 21 becomes a concave and convex surface by ink coating, so it is not preferred to bond on such a surface in terms of heat conduction and operation.

[0069] According to this embodiment, the spacer 4 is positioned radially with the second lens 22 via the socket 41. The radial clearance between the socket 41 and the second lens 22 is smaller than the radial clearance CL1 between the socket 41 and the first inner peripheral surface 31a of the lens barrel 3.

[0070] Thus, the spacer 4 can be positioned so as not to contact the lens barrel 3. Therefore, it is possible to avoid the heat of the heating portion 51 transmitted to the spacer 4 being taken away by the lens barrel 3. Furthermore, the first lens 21 can be heated appropriately.

[0071] Furthermore, according to the present embodiment, the spacer 4 is arranged on the outer diameter side of the imaging optical path of the lens unit 1 .

[0072] Therefore, the spacer 4 does not affect the optical performance of the lens unit 1 regardless of the assembly state.

[0073] According to the present embodiment, the heating unit 51 is bonded to the image-side surface 4 b of the spacer 4 by the adhesive layer 54 which is a double-sided tape or adhesive having thermal conductivity.

[0074] Thereby, the heat of the heating unit 51 can be appropriately transferred to the spacer 4 .

[0075] Furthermore, according to the present embodiment, the heating portion 51 may be sandwiched in the axial direction by the fixing member 7 having a lower thermal conductivity than the spacer 4 .

[0076] According to this structure, the heating portion 51 can be appropriately brought into contact with the spacer 4 without bonding the heating portion 51 to the spacer 4 .

[0077] Furthermore, according to the present embodiment, the thermistor 53 is disposed in the heating unit 51 .

[0078] Thus, the temperature of the heating unit 51 can be detected relatively accurately, and the temperature of the first lens 21 can be appropriately controlled.

[0079] [other]

[0080] Although one embodiment of the present invention has been described above, the embodiment to which the present invention can be applied is not limited to the above-described embodiment and its modified examples, and can be appropriately modified within the scope not departing from the gist of the present invention.

[0081] For example, in the above-described embodiment, the first lens is heated to melt frozen ice or snow on the surface, but the first lens may be heated for other purposes such as removing fogging of the first lens.

Claims

1. A lens unit, wherein: have: An optical system including, from the object side, a first lens and a second lens; a spacer sandwiched between the image-side surface of the first lens and the object-side surface of the second lens; and The heating portion is in contact with the spacer to heat the image-side surface of the first lens.

2. The lens unit according to claim 1, wherein: The axial position of the heating portion is offset from between the image-side surface of the first lens and the object-side surface of the second lens sandwiching the spacer.

3. The lens unit according to claim 2, wherein: The heating portion is in contact with the image-side surface of the spacer.

4. The lens unit according to claim 1, wherein: The lens unit includes a lens barrel that accommodates the optical system and the spacer. The spacer has a socket for radially positioning the spacer and the first lens or the second lens relative to each other. A radial gap between the socket and the first lens or the second lens is smaller than a radial gap between the socket and the inner circumferential surface of the lens barrel.

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

6. The lens unit according to claim 1, wherein: The heating unit is bonded to the image side surface of the spacer by a double-sided tape or an adhesive having thermal conductivity.

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

8. The lens unit according to claim 1, wherein: The heating portion is sandwiched in the axial direction by a fixing member having a lower thermal conductivity than the spacer.

9. The lens unit according to claim 1, wherein: The heating unit is provided with a thermistor.

10. The lens unit according to claim 1, wherein: The heating portion is formed in a ring shape or a horseshoe shape.

11. The lens unit according to claim 1, wherein: The heating part is an FPC heater.

12. A camera module, wherein: have: The lens unit according to any one of claims 1 to 11; and The imaging element performs photoelectric conversion on the subject image formed by the optical system.

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