lens unit

Abstract

To provide a lens unit that suppresses displacement of each lens caused by temperature change. Means for solving the problem is that the lens unit (100) has: a first lens group (123) including one or more glass lenses; a second lens group (145) including one or more plastic lenses; a lens barrel (18) housing the first lens group and the second lens group; a first retainer (10) that screws the first lens group to the lens barrel; and a second retainer (17) that screws the second lens group to the lens barrel.

Description

Technical Field

[0001] This invention relates to lens units. Background Technology

[0002] Previously, techniques for reducing lens loosening in lens units or lens holding structures have been proposed. As such a technique, for example, a lens unit is known to have a resin lens barrel on which multiple lenses are assembled, and the lenses are secured by a retainer (see, for example, Patent Document 1).

[0003] Furthermore, as described above, a structure is known that has a lens with an optical surface and a non-optical surface, wherein a plurality of guide portions are integrally provided on one of the non-optical surface and the surface of the lens barrel facing the non-optical surface, and an engaging portion for engaging the guide portions is provided on the other surface (for example, see Patent Document 2).

[0004] Furthermore, as described above, a lens holding structure is known, comprising one or more lenses; a lens frame member for holding the one or more lenses; and a pressing member connected to the front end surface of the lens frame member and elastically pressing the foremost lens (for example, see Patent Document 3).

[0005] Prior art literature

[0006] Patent documents

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2019-179179

[0008] [Patent Document 2] Japanese Patent Application Publication No. 2010-78920

[0009] [Patent Document 3] Japanese Patent Application Publication No. 2017-161650 Summary of the Invention

[0010] The problem that the invention aims to solve

[0011] The lens unit must withstand temperature changes in accordance with the operating environment. Even if such temperature changes occur, it is necessary to suppress lens displacement within the lens unit.

[0012] However, in the technology of Patent Document 1, deformation of the plastic lens may occur due to the pressing and assembly of the lens. Furthermore, when the plastic lens expands or contracts in the direction of compression due to a rapid temperature change, the deformation of the plastic lens increases further, making it difficult to suppress the deformation of the plastic lens below a predetermined value.

[0013] Furthermore, in the technology of Patent Document 2, since there is no force acting in the direction of the optical axis, the position of the lens and the optical axis sometimes changes.

[0014] Furthermore, in the technology of Patent Document 3, all internal components need to be held in place by a pressing member. Therefore, when the internal components include both a glass lens and a plastic lens, a large force is required to hold the heavier glass lens in place. Moreover, because a large force is applied to the plastic lens, it is prone to deformation.

[0015] One objective of this invention is to provide a lens unit comprising both a glass lens and a plastic lens, which is capable of suppressing displacement of the lenses caused by temperature changes.

[0016] Methods for solving problems

[0017] To address the aforementioned issues, one aspect of the present invention relates to a lens unit comprising: a first lens group including one or more glass lenses; a second lens group including one or more plastic lenses; a lens barrel housing the first lens group and the second lens group; a first retainer for screwing the first lens group onto the lens barrel; and a second retainer for screwing the second lens group onto the lens barrel.

[0018] Invention Effects

[0019] According to one aspect of the present invention, a lens unit comprising both a glass lens and a plastic lens can suppress displacement of the individual lenses caused by temperature changes. Attached Figure Description

[0020] Figure 1 This is a cross-sectional view showing the structure of the lens unit involved in Embodiment 1.

[0021] Figure 2 This is an exploded perspective view showing the various structures of the lens unit involved in Embodiment 1 and the main body of the imaging device.

[0022] Figure 3 This is a cross-sectional view showing the structure of the lens unit involved in Embodiment 2.

[0023] Figure 4 This is an exploded perspective view showing the various structures of the lens unit involved in Embodiment 2 and the main body of the imaging device.

[0024] Explanation of reference numerals in the attached figures:

[0025] 100, 100a lens units

[0026] 10. Object-side retainers (first retainer)

[0027] 101 Tightening part (first tightening part)

[0028] 102. First cylindrical section (or section 1)

[0029] 103 Card Section

[0030] 11, 12, 13 Glass lenses

[0031] 123 First lens group

[0032] 14, 15 Plastic lenses

[0033] 145 Second Lens Group

[0034] 140 trench

[0035] 16 spacers

[0036] 17, 17a, 17b Image plane side retainer (second retainer)

[0037] 170 Tightening part (second tightening part)

[0038] 170 screw joint

[0039] 171, 171a Cylindrical section (second cylindrical section)

[0040] 173 Top Edge

[0041] 174 protrusions

[0042] 175 Opening

[0043] 18 Lens tubes

[0044] 18A First Space

[0045] 18B Second Space

[0046] 180 bulge

[0047] 181. Stepped section (retaining section)

[0048] 19 Lenses

[0049] 210 Main body of the camera device Detailed Implementation

[0050] The following describes an embodiment of the lens unit according to the present invention. However, the lens unit described below is one embodiment of the lens unit according to the present invention, and the lens unit according to the present invention is not limited to the following embodiment.

[0051] [Implementation Method 1]

[0052] (Overall structure)

[0053] First, refer to Figure 1 as well as Figure 2 This describes the overall structure of the lens unit 100 involved in this embodiment.

[0054] Figure 1 This is a cross-sectional view showing the structure of the lens unit 100 according to this embodiment. More specifically, Figure 1 It is a cross-sectional view obtained by cutting along an axial section plane, including the fitting position between the first fitting part 140 and the second fitting part 180, which will be described later.

[0055] Figure 2 It means Figure 1 An exploded perspective view of the various structures of the lens unit 100 and the main body 210 of the camera device.

[0056] like Figure 1 As shown, the lens unit 100 includes: a first lens group 123, a second lens group 145, an object-side retainer (first retainer) 10, a spacer 16, an image-side retainer (second retainer) 17, and a lens barrel 18. The lens unit 100 is configured to be held by the main body 210.

[0057] (The composition of each department)

[0058] The first lens group 123 and the second lens group 145 are housed in the lens barrel 18. The first lens group 123, for example, includes three glass lenses 11-13, and the second lens group 145, for example, includes two plastic lenses 14 and 15. All of the lenses have structures for determining their radial position. Examples of such positioning structures include: a concave strip and a convex strip that fits therewith; a hole and a boss that fits therewith; a convex surface of one lens having a specific shape; a concave surface of the adjacent lens that matches the aforementioned specific shape; and an outer peripheral wall of the lens and an inner peripheral wall of the lens barrel 18 that abuts therewith. In this way, multiple lenses are configured such that, when housed in the lens barrel 18, they can be guided radially to a specific position.

[0059] Furthermore, this embodiment shows three glass lenses and two plastic lenses, but the number of glass lenses and plastic lenses is not limited to this; the number of glass lenses can be one, two, or more than four. Similarly, the number of plastic lenses can be one or more.

[0060] The outer edge of the plastic lens 14 has a groove 140 extending along the thickness direction of the plastic lens 14. The groove 140 is provided at three locations on the outer edge of the plastic lens 14. More specifically, the groove 140 is provided at three symmetrical positions with respect to the center of the plastic lens 14 when viewed from above.

[0061] The object-side retainer 10 is generally cylindrical, made of resin, and has elasticity. The object-side retainer 10 includes: a first screw-on portion 101, screwed onto the outer periphery of the lens barrel 18; a first cylindrical portion 102, connected to the screw-on portion 101 to cover the outer periphery of the lens barrel 18; and an engaging portion 103 formed on the inner peripheral surface of the object-side opening of the first cylindrical portion 102. Here, the engaging portion 103 engages with the glass lens 11, which is the lens closest to the object side in the first lens group 123.

[0062] Spacer 16 is a spacer located between glass lens 12 and glass lens 13. Spacer 16 forms a gap of a predetermined size between glass lens 12 and glass lens 13 in the axial direction. On the object-facing end edge of spacer 16 that is in contact with glass lens 12, a plurality of (e.g., six) protrusions are formed.

[0063] The image-side retainer 17 is generally cylindrical. Furthermore, the image-side retainer 17 is made of resin and is elastic. The image-side retainer 17 includes: a screw portion (second screw portion) 170 located on the image-side; and a cylindrical portion (second cylindrical portion) 171 connected to the screw portion 170 and located closer to the object side than the screw portion 170.

[0064] The screw-in portion 170 has a threaded portion 172 on its outer peripheral surface and an internal thread on its inner peripheral surface. The threaded portion 172 is, for example, an external thread.

[0065] The cylindrical portion 171 is a cylindrical part with a plurality of (e.g., six) protrusions 174 arranged circumferentially at equal intervals on its end face facing the object.

[0066] The lens barrel 18 is a generally cylindrical component made of resin, with openings at both ends on the object side and the image plane side. As an example, the lens barrel 18 can be made of fiber-reinforced resin, but this is not a limitation of this embodiment. Furthermore, as... Figure 1 As shown, the lens barrel 18 has a stepped portion (holding portion) 181. Inside the lens barrel 18, a first space 18A is formed closer to the object side than the stepped portion 181, and a second space 18B is formed closer to the image plane side than the stepped portion 181.

[0067] An external thread is formed on the outer peripheral surface of the lens barrel 18 on the object-facing side in the axial direction. This external thread is formed to engage with an internal thread on the inner peripheral surface of the object-facing retainer 10. In addition, an internal thread is formed on the inner peripheral surface of the lens barrel 18 on the image-facing side in the axial direction. This internal thread is formed to engage with the threaded portion 172 of the image-facing retainer 17.

[0068] In addition, such as Figure 1As shown, a stepped portion 181 protruding from the inner peripheral wall is formed at the central part of the axial direction of the lens barrel 18. The stepped portion 181 is a generally annular part when viewed along the axial direction, and the two end faces of the stepped portion 181 in the axial direction of the lens barrel 18 are planes extending from the inner peripheral wall of the lens barrel 18 in a direction orthogonal to the axial direction of the lens barrel 18.

[0069] On the image plane side end face, a protrusion 180 is formed protruding from the end face. The protrusion 180 is positioned in a three-dimensionally symmetrical manner with the center of the stepped portion 181 as the center of symmetry. The protrusion 180 is formed to fit into the groove 140 of the plastic lens 14.

[0070] In addition, the lens barrel 18 is made of a material with a relatively small coefficient of linear expansion compared to the plastic lens 14.

[0071] (Configuration)

[0072] First, the arrangement of the lens on the object-facing side, i.e., the first space 18A side, which is further from the aforementioned stepped portion 181, will be described. Starting from the object-facing opening of the lens barrel 18, the glass lens 13, spacer 16, glass lens 12, and glass lens 11 are sequentially housed. Next, the object-facing retainer 10 covers the lens barrel 18 from the opening side, and the internal thread on the inner circumferential surface of the object-facing retainer 10 engages with the external thread on the object-facing side of the outer circumferential surface of the lens barrel 18. Thus, the object-facing retainer 10 enters towards the body 210 along the axial direction of the lens barrel 18 and is secured to the lens barrel 18.

[0073] As previously described, glass lens 13, spacer 16, glass lens 12, and glass lens 11 are all suitably configured for positioning such that their optical axes coincide radially with each other in the lens barrel 18. Therefore, in this radial direction, at a position with the axis of the lens barrel 18 as the optical axis, glass lenses 13, 12, and 11 are housed in the lens barrel 18 closer to the object side than the aforementioned stepped portion 181. In this way, the first lens group 123 is housed within the lens barrel 18, with glass lens 13 abutting against the stepped portion 181, and is housed in the first space 18A, and is screwed between the object-side retainer 10 and the stepped portion 181.

[0074] Furthermore, the glass lens 11 engages with the aforementioned engaging portion 103 of the object-side retainer 10, and is pressed towards the main body 210 side as a result of the aforementioned tightening. Thus, the object-side retainer 10 presses the glass lenses 11 and 12, the spacer 16, and the glass lens 13 from the object-side along the axial direction of the lens barrel 18. Therefore, the glass lenses 13, 12, and 11 are fixed to the lens barrel 18 at a position closer to the object-side than the aforementioned stepped portion 181, with the axis of the lens barrel 18 as the optical axis, and further to the object-side than the aforementioned stepped portion 181.

[0075] Next, the arrangement of the lens on the image plane side, i.e., the second space 18B side, which is further from the stepped portion 181, will be described. Starting from the opening on the image plane side of the lens barrel 18 on the main body 210, plastic lens 14 and plastic lens 15 are sequentially housed. Plastic lens 14 abuts against the stepped portion 181 at its peripheral edge, and each of the three protrusions 180 rising from the stepped portion 181 engages with each of the three grooves 140 of the plastic lens 14. Thus, radial displacement of the plastic lens 14 is sufficiently suppressed.

[0076] Furthermore, as previously described, both plastic lenses 14 and 15 are suitably equipped with a positioning structure that aligns their optical axes with each other in the radial direction of the lens barrel 18. Therefore, in this radial direction, plastic lenses 14 and 15 are housed within the lens barrel 18 at a position closer to the image plane than the aforementioned stepped portion 181, with the axis of the lens barrel 18 as the optical axis.

[0077] The image-side retainer 17 is inserted into the lens barrel 18 through an opening on the image-side. The threaded portion 172 on the screw-in portion 170 of the image-side retainer 17 engages with the internal thread on the inner circumferential surface of the lens barrel 18. Thus, the image-side retainer 17 enters along the axial direction of the lens barrel 18 towards the object side and is secured to the lens barrel 18. As previously described, the image-side retainer 17 is made of resin, and the barrel portion 171 abuts against the plastic lens 15. Therefore, while the plastic lens 14 and plastic lens 15 are subjected to force along the axial direction of the lens barrel 18 due to the elasticity of the image-side retainer 17, their positions within the lens barrel 18 with the axis of the lens barrel 18 as the optical axis are fixed. In this way, the second lens group 145 abuts against the stepped portion 181 within the lens barrel 18 with the plastic lens 14, is housed in the second space 18B, and is screwed between the image-side retainer 17 and the stepped portion 181. As described above, since lens groups 123 and 145 abut against the stepped portion 181 inside the lens barrel 18, the tightening force of the retaining members 10 and 17 can be adjusted appropriately.

[0078] The object-facing end face of the image-side retainer 17 has a protrusion 174 as described above, and the cylindrical portion 171 abuts against the plastic lens 15 via the protrusion 174. Therefore, the cylindrical portion 171 abutting against the plastic lens 15 will have a moderate elasticity. Therefore, the image-side retainer 17 presses the plastic lenses 14 and 15 with a more appropriate pressing force.

[0079] Furthermore, as previously described, the lens barrel 18 is made of a material with a relatively small coefficient of linear expansion compared to the plastic lens 14. Therefore, if the groove 140 and the protrusion 180 are substantially the same size at room temperature, the size of the groove 140 increases at high temperatures. This prevents the groove 140 from being pressed down due to the expansion of the protrusion 180 at high temperatures, thus preventing deformation of the plastic lens 14. Even in this case, the image-side retainer 17, with its elasticity, properly presses the plastic lenses 14 and 15 toward the stepped portion 181 along the axial direction. Therefore, even if a gap is formed between the protrusion 180 and the groove 140, radial positional deviation of the plastic lenses 14 and 15 can be prevented.

[0080] In this way, in the lens unit 100, the plastic lenses 14 and 15 are fixed to the lens barrel 18 using the image plane side retainer 17. Therefore, compared with the case where the plastic lens 14 is accommodated by pressing, the distortion of the plastic lens and the lens barrel can be suppressed.

[0081] Furthermore, the lens unit 100, through the engagement of the groove 140 and the protrusion 180, can appropriately suppress radial displacement of the plastic lens 14. Additionally, since the image-plane side retainer 17 appropriately presses the plastic lenses 14 and 15 axially, displacement of the plastic lenses 14 and 15 in the optical axis direction is appropriately suppressed, and radial displacement is also sufficiently suppressed. Therefore, even if the temperature varies within a temperature range including higher temperatures, the lens unit 100 can appropriately suppress displacement of the plastic lenses.

[0082] (The tightening force between the object-side retainer and the image-side retainer)

[0083] Here, the tightening force between the object-side retainer 10 and the image-side retainer 17 will be explained. The object-side retainer 10 and the image-side retainer 17 tighten the first lens group 123 and the second lens group 145 to the lens barrel 18 such that the tightening force of the object-side retainer 10 on the first lens group 123 is greater than the tightening force of the image-side retainer 17 on the second lens group 145.

[0084] Typically, the specific gravity of the material of glass lenses 11-13 can be 2 to 3 times that of the material of plastic lenses 14 and 15. Therefore, when vibration or impact is applied to the lens unit 100, the first lens group 123, which includes glass lenses 11-13, generates a greater impact force than the second lens group 145, which includes plastic lenses 14 and 15.

[0085] In this embodiment, the tightening force of the object-side retainer 10 on the glass lenses 11 to 13 is greater than the tightening force of the image-side retainer 17 on the plastic lenses 14 and 15. Therefore, the glass lenses 11 to 13 can be tightened appropriately without causing displacement of the plastic lenses 14 and 15 due to excessive tightening force.

[0086] (Effect)

[0087] As explained above, even if temperature changes occur, the lens unit 100 can effectively suppress the displacement of each lens in the lens group.

[0088] As an example of the application of lens unit 100, a lens unit for automotive sensors can be cited. In this application, it is sometimes required that the lens unit can be used in panoramic focusing and maintain its performance even at high temperatures, such as below -40°C on the low-temperature side and above 100°C on the high-temperature side. Furthermore, it is sometimes required that no performance degradation occur even in long-term storage tests at high temperatures of 120 to 125°C.

[0089] In the past, in consumer products with autofocus mechanisms, or in observation lens units that often use hundreds of thousands to 2 million pixels even in panoramic focusing, there were no problems in actual use even if the lens deformation or displacement caused by holding was a few micrometers to tens of micrometers.

[0090] However, sometimes in the automotive sensing lens units described above, it is also required to suppress their displacement to less than 1 micrometer.

[0091] Fiber-reinforced plastic lens barrels are frequently used as durable materials for lens barrels in such environments. However, fiber-reinforced plastic lens barrels exhibit anisotropy in both the resin flow direction (MD) and the direction perpendicular to the flow (TD). Therefore, as an example, when the coefficient of linear expansion in the MD direction is set to 1.5 × 10⁻⁶... -5 Furthermore, the coefficient of linear expansion in the TD direction is 3.0 × 10⁻⁶. -5 Sometimes, the displacement exceeds the allowable amount for a lens unit used as an in-vehicle sensor.

[0092] More specifically, when the temperature changes from 20°C to -40°C, the displacement Δ at a distance of 10 mm in each direction is -0.008 mm in the MD direction and -0.016 mm in the TD direction. Furthermore, when the temperature changes from 20°C to 120°C, the displacement is Δ0.015 mm in the MD direction and Δ0.03 mm in the TD direction. Thus, even fiber-reinforced plastic lens barrels, which are considered to be resistant to temperature changes, can deform due to differences in fiber orientation.

[0093] The same applies to plastic lenses. For example, if the outer diameter is 10mm, the coefficient of linear expansion is 7.0 × 10⁻⁶. -5 Then, when the temperature changes from 20℃ to -40℃, the displacement Δ of the outer diameter of the plastic lens is... L The value is -0.042 mm. During a temperature change from 20℃ to 120℃, Δ...L It is 0.07mm.

[0094] Generally speaking, in the case where the structure holds the plastic lens by radial pressing, due to thermal expansion and contraction, there may be a large looseness between the outer diameter of the plastic lens and the inner diameter of the lens barrel, and the lens may shift.

[0095] However, according to the lens unit 100 of this embodiment, even in an environment with a large difference in the coefficient of linear expansion between the plastic lens and the lens barrel and a large temperature difference of -40°C to 120°C, it is possible to suppress the deformation of the plastic lens while maintaining high precision in positioning and holding it.

[0096] In addition, since the resin used for the plastic lens barrel has a large orientation difference, even if the lens barrel expands and contracts unevenly, the force of the image plane side retainer 17 can prevent the plastic lens from shifting position.

[0097] Furthermore, the smaller the diameter of the protrusion in the second fitting portion 180 and the width of the groove in the first fitting portion 140, the better it can suppress deformation caused by dimensional changes due to temperature differences ΔT relative to room temperature.

[0098] Thus, the lens unit 100 according to this embodiment can maintain high precision even in the event of thermal expansion and contraction without causing lens displacement.

[0099] Furthermore, as described above, since the object-side retainer 10 tightens the first lens group 123 and the second lens group 145 to the lens barrel 18 in such a way that the tightening force of the object-side retainer 10 on the first lens group 123 is greater than the tightening force of the image-side retainer 17 on the second lens group 145, the object-side retainer 10 and the image-side retainer 17 can properly tighten the glass lenses 11 to 13 without causing the plastic lenses 14 and 15 to shift due to excessive tightening force.

[0100] (A variation of Implementation Method 1)

[0101] The configuration of positioning and fixing the plastic lens 14 radially in the lens barrel 18 is not limited to the groove 140 and the protrusion 180. For example, the lens barrel 18 may have a groove and the plastic lens 14 may have a protrusion.

[0102] Furthermore, the lens unit 100 may have further components within the range that achieves the effects of this embodiment. For example, the lens unit 100 may be configured to have an optical component between the plastic lens 14 and the image-side retainer 17, either in place of or simultaneously with the plastic lens 15, and this optical component may include at least one of other lenses, spacers, and light-shielding gaskets. In such a configuration, the image-side retainer 17 also presses against the other lenses, spacers, and light-shielding gaskets in the optical axis direction. Therefore, displacement of these optical components relative to the optical axis can be appropriately suppressed.

[0103] [Implementation Method 2]

[0104] Other embodiments of the present invention will be described below. Furthermore, for ease of explanation, the same reference numerals are assigned to components having the same function as those described in the above embodiments, and will not be described again.

[0105] Figure 3 This is a cross-sectional view showing the structure of the lens unit 100a according to this embodiment. More specifically, Figure 3 It is a cross-sectional view obtained by cutting along an axial section plane, including their fitting positions, with the first fitting part 140 and the second fitting part 180 fitted together. Figure 4 It means Figure 3 An exploded perspective view of the various structures of the lens unit 100a and the main body 210 of the imaging device.

[0106] like Figure 3 and Figure 4 As shown, the lens unit 100a includes a first image-side retainer 17a and a second image-side retainer 17b, replacing the image-side retainer 17 of the lens unit 100 according to Embodiment 1. Furthermore, a lens 19 is provided between the first image-side retainer 17a and the second image-side retainer 17a. The lens 19 is, for example, a glass lens, and is housed in a position where the axis and optical axis of the lens barrel 18 are aligned radially by fitting the peripheral portion of the lens 19 into a stepped portion 181 formed on the inner peripheral wall of the first image-side retainer 17a. The other structures of the abutting lens unit 100a are the same as those of the lens unit 100 according to Embodiment 1.

[0107] The first image-side retainer 17a is the same as the image-side retainer 17 according to Embodiment 1, and the plastic lenses 14 and 15 are housed inside the lens barrel 18 by pressing the plastic lenses 14 and 15 axially toward the lens barrel 18. As an example, the first image-side retainer 17a is the same as the image-side retainer 17 according to Embodiment 1, and is screwed to the inner circumference of the lens barrel 18.

[0108] The second image-side retainer 17b houses the lens 19 within the lens barrel 18 by pressing the lens 19 axially toward the lens barrel 18. Here, the second image-side retainer 17b, as an example, is... Figure 3 As shown, the lens 19 is screwed onto the inner circumference of the first retainer 17a. This screwing secures the lens 19 by pressing it axially toward the object side with appropriate strength and elasticity.

[0109] In addition, such as Figure 3 and Figure 4 As shown, the first image plane side retainer 17a includes a screw portion 170 and a cylindrical portion 171a. Here, since the screw portion 170 is the same as in Embodiment 1, its description is omitted.

[0110] The cylindrical portion 171a has a plurality of protrusions 174 that project axially from the top edge 173 of the cylindrical portion 171a. These plurality of protrusions 174 abut against the plastic lens 15, which is the image-side lens among a plurality of plastic lenses, from the image plane side, and press the plastic lens 15 and the plastic lens 14 in the optical axis direction.

[0111] Additionally, the cylindrical section 171a, as Figure 4 As shown, it has multiple openings 175. In this way, by providing multiple openings to the cylindrical portion 171a, the elasticity of the first retainer 17a can be made more suitable, thereby appropriately suppressing the displacement of the plastic lens in the optical axis direction.

[0112] In addition, such as Figure 4 As shown, each of the plurality of openings 175 is positioned at a position corresponding to each of the plurality of protrusions 174. In this way, by establishing a correspondence between the positions of the openings 175 and the protrusions 174, the plurality of plastic lenses can be pressed more appropriately.

[0113] In addition, Figure 4 In the example shown, the number of openings 175 and protrusions 174 is set to 3, but this is not a limitation of this embodiment and can be any number other than 3.

[0114] 〔Summarize〕

[0115] The lens unit according to Embodiment 1 of the present invention comprises: a first lens group including one or more glass lenses; a second lens group including one or more plastic lenses; a lens barrel housing the first lens group and the second lens group; a first retainer for screwing the first lens group onto the lens barrel; and a second retainer for screwing the second lens group onto the lens barrel.

[0116] Based on this structure, even if temperature changes occur, displacement of each lens can be suppressed.

[0117] The lens unit involved in Method 2 of the present invention can also be in Method 1, where the first retainer and the second retainer are elastic.

[0118] According to this structure, since the object-side retainer is elastic, appropriate pressing force can be applied to the first lens group. Similarly, since the image-side retainer is elastic, appropriate pressing force can be applied to the second lens group.

[0119] The lens unit involved in the third aspect of the present invention can also be in aspect 1 or 2, in which the first retainer and the second retainer are screwed to the lens barrel in such a way that the screwing force of the first retainer on the first lens group is greater than the screwing force of the second retainer on the second lens group.

[0120] According to this structure, in addition to the effects of method 1 or 2, more appropriate pressing pressure can be applied to both glass and plastic lenses.

[0121] The lens unit involved in embodiment 4 of the present invention may also be in any of embodiments 1 to 3, wherein the lens barrel further includes a holding portion abutting the first lens group and the second lens group.

[0122] Based on this structure, it is relatively easy to properly adjust the screwing force of each retainer for each lens group that abuts against the retainer inside the lens barrel.

[0123] The lens unit involved in embodiment 5 of the present invention may also be in any of embodiments 1 to 4, wherein the first retaining member comprises: a first screwing portion, which is screwed onto the outer periphery of the lens barrel; a first cylindrical portion, which is connected to the screwing portion and covers the outer periphery of the lens barrel; and an engaging portion, which engages with the first lens group.

[0124] According to this structure, in addition to the effects of any of methods 1 to 4, it is also possible to apply more appropriate pressing pressure to the glass lens.

[0125] The accessory adapter according to embodiment 6 of the present invention may also be in any of embodiments 1 to 5, wherein the second retainer comprises: a second screw portion, screwed to the inner circumference of the lens barrel; and a second cylindrical portion, connected to the screw portion, wherein a plurality of openings are formed in the cylindrical portion.

[0126] According to this structure, in addition to the effects of any of methods 1 to 5, it is also possible to apply more appropriate pressing pressure to the plastic lens.

[0127] This invention is not limited to the embodiments described above, and various modifications can be made within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included within the technical scope of this invention.

Claims

1. A lens unit, characterized in that, have: The first lens group consists of only one or more glass lenses; The second lens group consists of only one or more plastic lenses; The lens barrel houses the first lens group and the second lens group; The first retaining member screws the first lens group onto the lens barrel; as well as The second retaining member screws the second lens group onto the lens barrel. The first retainer and the second retainer fasten the first lens group and the second lens group to the lens barrel in such a way that the screwing force of the first retainer on the first lens group is greater than the screwing force of the second retainer on the second lens group.

2. The lens unit as described in claim 1, characterized in that, The first retainer and the second retainer are elastic.

3. The lens unit as described in claim 1, characterized in that, The lens barrel also includes a holding portion abutting the first lens group and the second lens group.

4. The lens unit as described in claim 1, characterized in that, The first retaining member includes: The first screw-in part is screwed onto the outer periphery of the lens barrel; The first cylindrical portion is connected to the first screwed portion to cover the outer periphery of the lens barrel; as well as The engaging part engages with the first lens group.

5. The lens unit as described in claim 1, characterized in that, The second retaining member includes: The second screw-in part is screwed onto the inner circumference of the lens barrel; and The second cylindrical portion is connected to the second screw portion; Multiple openings are formed on the second cylindrical portion.

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