CN113433648A

CN113433648A - Lens unit

Info

Publication number: CN113433648A
Application number: CN202011309631.3A
Authority: CN
Inventors: 井上道夫
Original assignee: Tamron Co Ltd
Current assignee: Tamron Co Ltd
Priority date: 2020-03-05
Filing date: 2020-11-20
Publication date: 2021-09-24
Also published as: JP2021140044A

Abstract

The problem is to provide a lens unit which suppresses displacement of each lens caused by temperature change. The solution is that a lens unit (100) is provided with: a first lens group (123) comprising one or more glass lenses; a second lens group (145) comprising one or more plastic lenses; a lens barrel (18) that houses the first lens group and the second lens group; a first holder (10) that screws the first lens group to the lens barrel; and a second holder (17) that screws the second lens group to the lens barrel.

Description

Lens unit

Technical Field

The present invention relates to a lens unit.

Background

Conventionally, a technique for reducing lens looseness in a lens unit or a lens holding structure has been proposed. As such a technique, for example, a lens unit is known which has a resin barrel in which a plurality of lenses are assembled and screws the lenses with a holder (for example, see patent document 1).

As the above-described technique, a configuration is known in which a lens having an optical surface and a non-optical surface is provided, a plurality of guide portions are integrally provided on one of the non-optical surface and a surface of a lens barrel facing the non-optical surface, and an engagement portion for engaging the guide portions is provided on the other surface (see, for example, patent document 2).

Further, as the above-described technique, there is known a lens holding structure including one or a plurality of lenses; a lens frame member holding one or more lenses; and a pressing member that is coupled to a front end surface of the lens frame member and elastically presses the foremost lens (for example, refer to patent document 3).

Prior art documents

Patent document

[ patent document 1] Japanese patent application laid-open No. 2019-179179

[ patent document 2] Japanese patent application laid-open No. 2010-78920

[ patent document 3] Japanese patent laid-open publication No. 2017-161650

Disclosure of Invention

Problems to be solved by the invention

The lens unit is subject to temperature changes according to the use environment and the like. Even if such a temperature change occurs, it is required to suppress displacement of the lens in the lens unit.

However, in the technique of patent document 1, since the lens is assembled by press-fitting, there is a possibility that the plastic lens is deformed. Further, when expansion or contraction occurs in the direction in which the plastic lens is compressed due to a sharp temperature change, the deformation of the plastic lens further increases, so that it is difficult to suppress the deformation of the plastic lens below a predetermined value.

In addition, in the technique of patent document 2, since there is no force in the optical axis direction, there is a case where the position of the lens and the optical axis changes.

Further, in the technique of patent document 3, it is necessary to hold all internal constituent members by a pressing member. Therefore, when the internal constituent members include a glass lens and a plastic lens, a large force needs to be applied to hold the heavy glass lens. Further, since a large force is applied to the plastic lens, the plastic lens is easily deformed.

An object of one embodiment of the present invention is to provide a lens unit including both a glass lens and a plastic lens, which can suppress displacement of each lens due to temperature change.

Means for solving the problems

To solve the above problem, a lens unit according to an aspect of the present invention includes: a first lens group including one or more glass lenses; a second lens group including one or more plastic lenses; a lens barrel accommodating the first lens group and the second lens group; a first holder that screws the first lens group to the lens barrel; and a second holder that screws the second lens group to the lens barrel.

Effects of the invention

According to one aspect of the present invention, a lens unit including both a glass lens and a plastic lens can suppress displacement of each lens due to temperature change.

Drawings

Fig. 1 is a sectional view showing a structure of a lens unit according to embodiment 1.

Fig. 2 is an exploded perspective view showing the respective configurations of the lens unit according to embodiment 1 and the main body of the imaging device.

Fig. 3 is a sectional view showing the structure of the lens unit according to embodiment 2.

Fig. 4 is an exploded perspective view showing the respective configurations of the lens unit according to embodiment 2 and the main body of the imaging device.

Description of reference numerals:

100. 100a lens unit

10 pairs of object side holders (first holders)

101 screw fastening part (first screw fastening part)

102 barrel part (first barrel part)

103 engaging part

11. 12, 13 glass lens

123 first lens group

14. 15 Plastic lens

145 second lens group

140 groove

16 spacer

17. 17a, 17b image plane side holder (second holder)

170 screw fastening part (second screw fastening part)

170 screw part

171. 171a cylinder (second cylinder)

173 top edge

174 the protrusion

175 opening

18 lens barrel

18A first space

18B second space

180 convex part

181 step (holding part)

19 lens

210 main body of image pickup device

Detailed Description

Hereinafter, embodiments of the lens unit according to the present invention will be described. However, the lens unit described below is an embodiment of the lens unit according to the present invention, and the lens unit according to the present invention is not limited to the embodiment described below.

[ embodiment mode 1]

(Overall Structure)

First, the overall configuration of the lens unit 100 according to the present embodiment will be described with reference to fig. 1 and 2.

Fig. 1 is a sectional view showing a structure of a lens unit 100 according to the present embodiment. More specifically, fig. 1 is a cross-sectional view taken along an axial cross-section including a fitting position between a first fitting portion 140 and a second fitting portion 180, which will be described later.

Fig. 2 is an exploded perspective view showing each configuration of the lens unit 100 in fig. 1 and a main body 210 of the imaging device.

As shown in fig. 1, the lens unit 100 includes: a first lens group 123, a second lens group 145, an object side holder (first holder) 10, a spacer 16, an image plane side holder (second holder) 17, and a lens barrel 18. The lens unit 100 is configured to be held by the main body 210.

(constitution of each part)

The first lens group 123 and the second lens group 145 are housed by the lens barrel 18. The first lens group 123 includes, for example, three glass lenses 11 to 13, and the second lens group 145 includes, for example, two

plastic lenses

14 and 15. All the lenses described above have a structure for determining a position in the radial direction. Examples of such structures for positioning include: concave strips and convex strips embedded with the concave strips; a hole and a boss embedded with the hole; a convex surface having a specific shape of one lens; a concave surface of the other lens adjacent thereto, the concave surface being adapted to the specific shape; and an outer peripheral wall portion of the lens and an inner peripheral wall portion of the lens barrel 18 in contact therewith. In this manner, the plurality of lenses are configured to: when housed in the lens barrel 18, can be guided to a certain specific position in the radial direction.

In addition, in the present embodiment, three glass lenses and two plastic lenses are shown, but the number of glass lenses and plastic lenses is not limited thereto, and the number of glass lenses may be one or two, or four or more. The number of plastic lenses may be one or three or more.

The outer edge portion of the plastic lens 14 has a groove 140 extending in the thickness direction of the plastic lens 14. The grooves 140 are provided at three positions on the outer peripheral portion of the plastic lens 14. More specifically, the groove 140 is provided at a position of three times symmetry with the center of the plastic lens 14 as a center of symmetry in a plan view.

The object-side holder 10 is substantially cylindrical, is made of resin, and has elasticity. The object side holder 10 includes: a first screw 101 screwed to the outer circumference of the lens barrel 18; a first barrel portion 102 connected to the screw portion 101 to cover the outer periphery of the lens barrel 18; the engaging portion 103 is formed on the inner circumferential surface of the opening on the opposite side of the first cylindrical portion 102. Here, the engaging portion 103 engages with the glass lens 11, which is the lens closest to the opposite object side in the first lens group 123.

The spacer 16 is a spacer interposed between the glass lens 12 and the glass lens 13. The spacer 16 forms a gap of a predetermined size between the glass lens 12 and the glass lens 13 in the axial direction. A plurality of (for example, six) convex portions are formed on the edge on the opposite side of the spacer 16 that contacts the glass lens 12.

The image-side holder 17 is substantially cylindrical. Further, the image plane side holder 17 is made of resin and has elasticity. The image surface side holder 17 includes: a screw portion (second screw portion) 170 located on the image plane side; a cylindrical portion (second cylindrical portion) 171 is connected to the screw portion 170 and located closer to the opposite side than the screw portion 170.

The screw portion 170 has a screw portion 172 on an outer peripheral surface thereof and a female screw on an inner peripheral surface thereof. The threaded portion 172 is, for example, a male screw.

The cylindrical portion 171 is a cylindrical portion, and has a plurality of (for example, six) projections 174 arranged at equal intervals in the circumferential direction on the end surface on the opposite side.

The lens barrel 18 is a substantially cylindrical resin member, and has openings on both the object side and the image plane side. As an example, the lens barrel 18 may be made of a fiber-reinforced resin, but this is not a limitation of the present embodiment. As shown in fig. 1, the lens barrel 18 has a step portion (holding portion) 181. In the lens barrel 18, a first space 18A is formed on the opposite side of the step portion 181, and a second space 18B is formed on the image plane side of the step portion 181.

A male screw is formed on an outer peripheral surface of the lens barrel 18 on the opposite side in the axial direction. The male screw is formed to be screwed into a female screw on the inner peripheral surface of the object side holder 10. In addition, a female screw is formed on the inner peripheral surface of the image surface side of the lens barrel 18 in the axial direction. The female screw is formed to be screwed into the screwing portion 172 of the image plane side holder 17.

As shown in fig. 1, a stepped portion 181 protruding from the inner peripheral wall surface is formed at the axial center of the lens barrel 18. The stepped portion 181 is a substantially annular portion when viewed in the axial direction, and both end surfaces of the stepped portion 181 in the axial direction of the lens barrel 18 are planes extending from the inner circumferential wall surface of the lens barrel 18 in a direction orthogonal to the axial direction of the lens barrel 18.

On the end surface on the image surface side, a convex portion 180 protruding from the end surface is formed. The convex portion 180 is provided at a position three times symmetrical with the center of the step portion 181 as a symmetry center. The convex portion 180 is formed in a shape to be fitted into the groove 140 of the plastic lens 14.

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

(configuration)

First, the arrangement of the lens on the object side, that is, the first space 18A side, with respect to the stepped portion 181 will be described. The glass lens 13, the spacer 16, the glass lens 12, and the glass lens 11 are housed in this order from the opening on the opposite side of the lens barrel 18. Next, the object side holder 10 covers the lens barrel 18 from the opening side of the lens barrel 18, and the female screw on the inner circumferential surface side of the object side holder 10 is screwed with the male screw on the object side on the outer circumferential surface of the lens barrel 18. Thereby, the object side holder 10 enters the main body 210 side along the axial direction of the lens barrel 18, and is fastened to the lens barrel 18.

As described above, the glass lens 13, the spacer 16, the glass lens 12, and the glass lens 11 each appropriately have a structure for positioning such that the positional relationship is such that the optical axes thereof coincide with each other in the radial direction of the lens barrel 18. Therefore, the glass lens 13, the glass lens 12, and the glass lens 11 are accommodated in the lens barrel 18 on the opposite side of the stepped portion 181 in the radial direction at a position around the axis of the lens barrel 18 as the optical axis. In this way, the first lens group 123 is accommodated in the first space 18A with the glass lens 13 in contact with the step portion 181 in the lens barrel 18, and is screwed between the object side holder 10 and the step portion 181.

The glass lens 11 is engaged with the engaging portion 103 of the object-side holder 10, and is pressed toward the main body 210 in accordance with the fastening. Thereby, the object side holder 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 lens 13, the glass lens 12, and the glass lens 11 are fixed to the lens barrel 18 on the opposite side of the stepped portion 181 and on the opposite side of the stepped portion 181 at a position on the optical axis of the lens barrel 18.

Next, the arrangement of the lenses on the image plane side, i.e., the second space 18B side, with respect to the step portion 181 will be described. The plastic lens 14 and the plastic lens 15 are accommodated in this order from the opening of the lens barrel 18 on the image plane side of the main body 210. The plastic lens 14 abuts the stepped portion 181 at its peripheral edge portion, and each of three convex portions 180 rising from the stepped portion 181 is fitted into each of the three grooves 140 of the plastic lens 14. Thereby, the displacement in the radial direction of the plastic lens 14 is sufficiently suppressed.

As described above, each of the

plastic lenses

14 and 15 has a structure for positioning that appropriately causes the optical axes to overlap each other in the radial direction of the lens barrel 18. Therefore, the

plastic lenses

14 and 15 are accommodated in the lens barrel 18 at positions closer to the image plane side than the stepped portion 181 and having the axis of the lens barrel 18 as the optical axis in the radial direction.

The image surface side holder 17 is inserted into the lens barrel 18 from an opening on the image surface side of the lens barrel 18. The screw portion 172 of the screw portion 170 of the image surface side holder 17 is screwed into the internal thread of the inner peripheral surface of the lens barrel 18. Thereby, the image plane side holder 17 enters toward the opposite object side along the axial direction of the lens barrel 18, and is fastened to the lens barrel 18. As described above, the image plane side holder 17 is made of resin, and the cylindrical portion 171 abuts against the plastic lens 15. Therefore, the

plastic lenses

14 and 15 are biased in the axial direction of the lens barrel 18 by the elasticity of the image surface side holder 17, and the positions of the lens barrel 18 are fixed within the lens barrel 18 with the axis of the lens barrel 18 as the optical axis. In this way, the second lens group 145 is held in the second space 18B with the plastic lens 14 in contact with the step 181 in the lens barrel 18, and is screwed tightly between the image surface side holder 17 and the step 181. As described above, since the

lens groups

123 and 145 are respectively abutted on the stepped portions 181 inside the lens barrel 18, the respective screwing forces of the

holders

10 and 17 can be appropriately adjusted.

The opposite-side end surface of the image plane side holder 17 has the projection 174 as described above, and the cylindrical portion 171 abuts against the plastic lens 15 via the projection 174. Therefore, the cylinder portion 171 abutting the plastic lens 15 generates appropriate elasticity. Therefore, the image plane side holder 17 presses the

plastic lenses

14, 15 with a more appropriate pressing force.

As described above, the lens barrel 18 is made of a material having a relatively small linear expansion coefficient compared to the plastic lens 14. Therefore, if the groove 140 and the protrusion 180 have substantially the same size at normal temperature, the size of the groove 140 becomes large at high temperature. Therefore, the plastic lens 14 is prevented from being deformed by the groove 140 pressed by the expansion of the convex portion 180 at a high temperature. Even in this case, the image plane side holder 17 appropriately presses the

plastic lenses

14, 15 toward the step portion 181 in the axial direction with its elasticity. Therefore, even if a gap is created between the convex portion 180 and the groove 140, the positional deviation of the

plastic lenses

14, 15 in the radial direction can be prevented.

In this manner, in the lens unit 100, the

plastic lenses

14, 15 are fixed to the lens barrel 18 using the image surface side holder 17. Therefore, as compared with the case where the plastic lens 14 is housed by press-fitting, the occurrence of distortion in the plastic lens and the lens barrel can be suppressed.

In addition, in the lens unit 100, displacement of the plastic lens 14 in the radial direction can be appropriately suppressed by fitting the groove 140 and the convex portion 180. In addition, since the image plane side holder 17 appropriately presses the

plastic lenses

14, 15 in the axial direction, displacement of the

plastic lenses

14, 15 in the optical axis direction is appropriately suppressed, and displacement thereof in the radial direction is also sufficiently suppressed. Therefore, even if the temperature varies within a temperature range including a higher temperature, the lens unit 100 can appropriately suppress displacement of the plastic lens.

(screw force between object side holder and image plane side holder)

Here, the screwing force between the object side holder 10 and the image plane side holder 17 will be described. The first lens group 123 and the second lens group 145 are screwed to the lens barrel 18 with respect to the object side holder 10 and the image plane side holder 17 such that the screwing force of the object side holder 10 to the first lens group 123 is greater than the screwing force of the image plane side holder 17 to the second lens group 145.

In general, the specific gravity of the material of the glass lenses 11 to 13 may be 2 to 3 times that of the material of the

plastic lenses

14 and 15. Therefore, when vibration or impact is applied to the lens unit 100, the first lens group 123 including the glass lenses 11 to 13 generates a larger impact force than the second lens group 145 including the

plastic lenses

14, 15.

In the present embodiment, the tightening force of the object-side holder 10 to the glass lenses 11 to 13 is greater than the tightening force of the image-side holder 17 to the

plastic lenses

14 and 15, so that the glass lenses 11 to 13 can be properly tightened without displacement of the

plastic lenses

14 and 15 due to excessive tightening force.

(Effect)

As described above, the lens unit 100 can sufficiently suppress displacement of each lens in the lens group even if a temperature change occurs.

As an example of an application of the lens unit 100, a vehicle-mounted sensing lens unit can be cited. In this application, it is sometimes required that the optical lens can be used in panoramic focusing and maintain performance even when the temperature is high at a temperature lower than-40 ℃ on the low temperature side and higher than 100 ℃ on the high temperature side. Furthermore, even in a long-term storage test at a high temperature of 120 to 125 ℃, it is sometimes required that no performance deterioration occurs.

Conventionally, in consumer products having an automatic focusing mechanism or in observation lens units in which around several hundred thousand to 200 thousand pixels are often used even in panoramic focus, there is no problem in actual use even if lens deformation or lens displacement due to holding is several micrometers to several tens micrometers.

However, in the above-described in-vehicle sensing lens unit, it is sometimes required to suppress the displacement to 1 μm or less.

As a lens barrel material that can be durable under such circumstances, a fiber-reinforced plastic lens barrel is often used. However, the fiber-reinforced plastic lens barrel has anisotropy in a resin flow direction (MD) and a direction perpendicular to the flow direction (TD). Therefore, for example, when the linear expansion coefficient in the MD direction is 1.5X 10^-5And a linear expansion coefficient in the TD direction of 3.0X 10^-5In this case, the displacement amount allowed for the in-vehicle sensor lens unit may be exceeded.

More specifically, when the temperature was changed from 20 ℃ to-40 ℃, the displacement amount Δ at the portion of distance 10mm in each direction was-0.008 mm in the MD direction and-0.016 mm in the TD direction, respectively. In addition, when the temperature was changed from 20 ℃ to 120 ℃, it was Δ 0.015mm in the MD direction and Δ 0.03mm in the TD direction, respectively. As described above, even in the fiber-reinforced plastic lens barrel which is considered to be resistant to temperature change, deformation may occur due to a difference in fiber orientation.

In addition, the same is true of plastic lenses. For example, if the outer diameter is 10mm, the linear expansion coefficient is 7.0X 10^-5When the temperature is changed from 20 ℃ to-40 ℃, the displacement amount Delta of the outer diameter of the plastic lens_LIs-0.042 mm, and has a temperature change of 20 ℃ to 120 ℃_LIs 0.07 mm.

In general, in the case where the structure is such that the plastic lens is held by being pressed radially, a large looseness may be generated between the outer diameter of the plastic lens and the inner diameter of the lens barrel due to expansion and contraction with heat, and a lens displacement movement may be generated.

However, according to the lens unit 100 of the present embodiment, even in an environment where the difference in linear expansion coefficient between the plastic lens and the lens barrel is large and there is a large temperature difference of-40 to 120 ℃, it is possible to perform positioning and holding with high accuracy while suppressing deformation of the plastic lens.

In addition, even if the lens barrel expands or contracts unevenly, the plastic lens can be prevented from being displaced by the biasing force of the image surface side holder 17.

Further, as the diameter of the convex portion provided in the second fitting portion 180 and the width of the groove provided in the first fitting portion 140 are smaller, the strain due to the dimensional change caused by the temperature difference Δ T at room temperature can be suppressed.

As described above, according to the lens unit 100 of the present embodiment, even when thermal expansion and contraction occur, high-precision holding can be achieved without causing lens displacement and movement.

Further, as described above, since the first lens group 123 and the second lens group 145 are screwed to the lens barrel 18 with respect to the object side holder 10 and the image plane side holder 17 so that the screwing force of the object side holder 10 to the first lens group 123 is larger than the screwing force of the image plane side holder 17 to the second lens group 145, the glass lenses 11 to 13 can be appropriately screwed without displacing the

plastic lenses

14 and 15 due to excessive screwing force.

(modification of embodiment 1)

The configuration of positioning and fixing the plastic lens 14 in the radial direction of the lens barrel 18 is not limited to the groove 140 and the convex portion 180. For example, the lens barrel 18 may have a groove, and the plastic lens 14 may have a convex portion.

Further, the lens unit 100 may have further members within a range in which the effects of the present embodiment can be obtained. For example, the lens unit 100 may be configured to include an optical member including at least one of another lens, a spacer, and a light shielding gasket between the plastic lens 14 and the image plane side holder 17 instead of or in addition to the plastic lens 15. In such a configuration, the image surface side holder 17 also presses other lenses, spacers, light shielding washers, and the like in the optical axis direction. Therefore, displacement of these optical members with respect to the optical axis can be appropriately suppressed.

[ embodiment 2]

Other embodiments of the present invention will be described below. For convenience of explanation, the same reference numerals are given to members having the same functions as those described in the above embodiments, and the description thereof will not be repeated.

Fig. 3 is a sectional view showing the structure of the lens unit 100a according to the present embodiment. More specifically, fig. 3 is a cross-sectional view taken along an axial cross-section including the fitting position of the first fitting portion 140 and the second fitting portion 180 in a state in which they are fitted. Fig. 4 is an exploded perspective view showing the respective structures of the lens unit 100a in fig. 3 and the main body 210 of the imaging device.

As shown in fig. 3 and 4, the lens unit 100a includes a first image plane side holder 17a and a second image plane side holder 17b instead of the image plane side holder 17 included in the lens unit 100 according to embodiment 1. Further, a lens 19 is provided between the first image plane side holder 17a and the second image plane side holder 17 a. The lens 19 is, for example, a glass lens, and the lens 19 is accommodated in a position where the axis of the lens barrel 18 and the optical axis are aligned in the radial direction by fitting the peripheral edge portion of the lens 19 to the stepped portion 181 formed on the inner peripheral wall of the first image surface side holder 17 a. The other configurations of the lens unit 100a in contact with each other are the same as those of the lens unit 100 according to embodiment 1.

The first image plane side holder 17a is similar to the image plane side holder 17 according to embodiment 1, and presses the

plastic lenses

14 and 15 in the axial direction of the lens barrel 18 to store the

plastic lenses

14 and 15 in the lens barrel 18. The first image plane side holder 17a is screwed to the lens barrel 18 by being screwed to the inner periphery of the lens barrel 18, as an example, in the same manner as the image plane side holder 17 according to embodiment 1.

The second image plane side holder 17b holds the lens 19 in the lens barrel 18 by pressing the lens 19 in the axial direction of the lens barrel 18. Here, the second image plane side holder 17b is screwed to the first holder 17a by being screwed to the inner periphery of the first holder 17a as shown in fig. 3, for example. By this screwing, the lens 19 is pressed and fixed to the object side in the axial direction with appropriate strength and elasticity.

As shown in fig. 3 and 4, the first image plane side retainer 17a includes a screw portion 170 and a cylindrical portion 171 a. Here, since the screw portion 170 is the same as embodiment 1, a description thereof is omitted.

The cylindrical portion 171a includes a plurality of projections 174 projecting in the axial direction from a distal end edge 173 of the cylindrical portion 171 a. The plurality of protrusions 174 abut on the plastic lens 15, which is a lens on the image plane side among the 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.

As shown in fig. 4, the cylindrical portion 171a has a plurality of openings 175. By providing the cylindrical portion 171a with a plurality of openings in this manner, the elasticity of the first holder 17a can be made more appropriate, and displacement of the plastic lens in the optical axis direction can be appropriately suppressed.

Further, as shown in fig. 4, each of the plurality of openings 175 is provided at a position corresponding to each of the plurality of protrusions 174. In this manner, by associating the positions of the opening 175 and the protrusion 174, the plurality of plastic lenses can be more appropriately pressed.

In addition, in the example shown in fig. 4, the number of the openings 175 and the projections 174 is set to 3, respectively, but this is not limiting to the present embodiment, and may be a number other than 3.

[ conclusion ]

A lens unit according to embodiment 1 of the present invention includes: a first lens group including one or more glass lenses; a second lens group including one or more plastic lenses; a lens barrel accommodating the first lens group and the second lens group; a first holder that screws the first lens group to the lens barrel; and a second holder that screws the second lens group to the lens barrel.

According to this configuration, even if a temperature change occurs, displacement of each lens can be suppressed.

In the lens unit according to mode 2 of the present invention, in mode 1, the first holder and the second holder may have elasticity.

According to this configuration, since the object side holder has elasticity, an appropriate pressing force can be applied to the first lens group. Likewise, since the image surface side holder has elasticity, an appropriate pressing force can be applied to the second lens group.

In the lens unit according to aspect 3 of the present invention, in aspect 1 or 2, the first holder and the second holder may screw-fasten the first lens group and the second lens group to the lens barrel such that a screwing force of the first holder to the first lens group is larger than a screwing force of the second holder to the second lens group.

According to this configuration, in addition to the effect of the aspect 1 or 2, a more appropriate pressing force can be applied to the glass lens and the plastic lens.

In the lens unit according to aspect 4 of the present invention, in any one of aspects 1 to 3, the lens barrel may further include a holding portion with which the first lens group and the second lens group are in contact.

With this configuration, it is easy to appropriately adjust the screwing force of each holder for each lens group that abuts against the holding portion in the lens barrel.

In the lens unit according to aspect 5 of the present invention, in any one of aspects 1 to 4, the first holder may include: a first screw-fastening portion screwed on the outer periphery of the lens barrel; a first cylindrical portion connected to the screw portion and covering an outer periphery of the lens barrel; and a clamping part clamped with the first lens group.

According to this structure, in addition to the effects of any of the modes 1 to 4, a more appropriate pressing force can be applied to the glass lens.

In the accessory adapter according to aspect 6 of the present invention, in any one of aspects 1 to 5, the second holder may include: a second screw-fastening section screwed to the inner circumference of the lens barrel; and a second cylindrical portion connected to the screw portion, the cylindrical portion having a plurality of openings formed therein.

According to this structure, in addition to the effect of any of the modes 1 to 5, a more appropriate pressing force can be applied to the plastic lens.

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

Claims

1. A lens unit is characterized by comprising:

a first lens group including one or more glass lenses;

a second lens group including one or more plastic lenses;

a lens barrel accommodating the first lens group and the second lens group;

a first holder that screws the first lens group to the lens barrel; and

and a second holder that screws the second lens group to the lens barrel.

2. The lens unit as recited in claim 1,

the first and second holders are elastic.

3. The lens unit according to claim 1 or 2,

the first holder and the second holder screw the first lens group and the second lens group to the lens barrel so that a screwing force of the first holder to the first lens group is larger than a screwing force of the second holder to the second lens group.

4. The lens unit according to any one of claims 1 to 3,

the lens barrel further includes a holding portion with which the first lens group and the second lens group are in contact.

5. The lens unit according to any one of claims 1 to 4,

the first holder includes:

a first screw portion screwed to an outer periphery of the lens barrel;

a first barrel portion connected to the first screw portion to cover an outer periphery of the lens barrel; and

and the clamping part is clamped with the first lens group.

6. The lens unit according to any one of claims 1 to 5,

the second holder includes:

a second screw-fastening section screwed to an inner periphery of the lens barrel; and

a second cylindrical portion connected to the second screw portion;

a plurality of openings are formed in the second cylinder portion.