JP2024043150A - lens unit - Google Patents

Abstract

[Problem] To suppress lens tilt when assembling multiple lenses inside a lens barrel and improve the quality of a lens unit. [Solution] An annular housing groove (30) for housing an O-ring (28) is formed in a part of a lens barrel (12) facing the peripheral part of the image side surface of the lens (14) closest to the object, and an annular positioning groove (32) for positioning the O-ring (28) is formed in the bottom surface of the housing groove (30). [Selected Figure] Figure 1

Description

The present invention relates to a lens unit.

A lens unit used in a camera such as a vehicle-mounted camera includes a lens barrel and a plurality of lenses provided within the lens barrel along an optical axis direction. In order to add a waterproof function to the lens unit, an O-ring is sometimes interposed between the lens closest to the object and the lens barrel. The O-ring is configured to seal the inside of the lens barrel by being crushed in the optical axis direction between the lens closest to the object and the lens barrel.

The lens unit described in Patent Document 1 has a waterproof function with the following configuration without interposing an O-ring between the lens closest to the object side and the lens barrel. That is, an annular recess is formed in a portion of the lens barrel that faces the peripheral edge of the image-side surface of the lens closest to the object. An annular elastic seal member formed by curing a applied liquid composition is provided in the concave portion of the lens barrel.

International Publication No. 2015/119296

By the way, when an O-ring is interposed between the lens closest to the object and the lens barrel, when assembling multiple lenses to the lens barrel, the O-rings are crushed while the multiple lenses are fixed to the lens barrel. There is a need to. Therefore, when assembling multiple lenses into a lens barrel, the reaction force of the O-ring will be biased due to the positional shift of the O-ring, resulting in misalignment or lens tilt of the multiple lenses, resulting in a decrease in the quality of the lens unit. may invite

Further, when an annular elastic seal member is provided in the recess of the lens barrel as in the lens unit described in Patent Document 1, the following problem occurs. It takes a long time for the liquid composition to be applied to the concave portion of the lens barrel and for the liquid composition to harden, which reduces the productivity of the lens unit. Furthermore, when applying a liquid composition to the entire circumference of the concave portion of the lens barrel, variations in the thickness of the liquid composition tend to occur, resulting in a gap between the lens closest to the object and the annular elastic seal member. Therefore, there is a concern that the quality of the lens unit may deteriorate.

Accordingly, one aspect of the present invention is to suppress lens tilt when assembling multiple lenses to the lens barrel when an O-ring is interposed between the lens closest to the object and the lens barrel, thereby improving the quality of the lens unit. The purpose is to increase

In order to solve the above-mentioned problems, one aspect of the present invention comprises a lens barrel and a plurality of lenses arranged within the lens barrel along the optical axis direction. A ring-shaped housing groove for housing an O-ring is formed in a portion of the lens barrel, facing the peripheral portion of the image-side surface of the lens closest to the object among the plurality of lenses, and the O-ring is configured to seal the inside of the lens barrel by being crushed in the optical axis direction between the lens closest to the object and the lens barrel, and a ring-shaped positioning groove for positioning the O-ring is formed in the bottom surface of the housing groove.

According to one aspect of the present invention, when an O-ring is interposed between the lens closest to the object and the lens barrel, lens tilt can be suppressed when assembling multiple lenses into the lens barrel, thereby improving the quality of the lens unit.

FIG. 2 is a schematic cross-sectional view of the lens unit according to Embodiment 1 along the optical axis direction. FIG. 2 is an enlarged sectional view of section II in FIG. 1. FIG. FIG. 7 is an enlarged cross-sectional view showing another aspect of the positioning groove of the lens unit according to the first embodiment. FIG. 7 is an enlarged cross-sectional view showing another aspect of the positioning groove of the lens unit according to the first embodiment. FIG. 3 is a schematic cross-sectional view for explaining some of the effects of the first embodiment. 7 is a schematic cross-sectional view along the optical axis direction of a lens unit according to Embodiment 2. FIG.

Embodiments of the present invention will be described below with reference to the drawings. In the specification and claims, the optical axis direction refers to the direction of the optical axis of a lens or the direction of the optical axis of a lens unit. The radial direction refers to the radial direction of a lens, the radial direction of a lens barrel, or the radial direction of a lens unit. In the drawings, "AD" refers to the optical axis, "B" refers to the object side (subject side), and "I" refers to the image side.

[Embodiment 1]
The configuration of the lens unit according to the first embodiment will be described with reference to FIGS. 1 to 4. FIG. 1 is a schematic cross-sectional view of a lens unit according to Embodiment 1 along the optical axis direction. FIG. 2 is an enlarged sectional view of section II in FIG. IIA in FIG. 2 shows a state in which a part of the O-ring crushed between the first lens and the lens barrel is engaged with the positioning groove. IIB in FIG. 2 shows a state in which a portion of the O-ring is engaged with the positioning groove before being crushed. 3 and 4 are enlarged sectional views showing other aspects of the positioning groove of the lens unit according to the first embodiment.
3 and 4 show a state in which a portion of the O-ring is engaged with the positioning groove before being crushed.

(Overview of lens unit 10)
As shown in FIG. 1, a lens unit 10 according to the first embodiment is an optical unit used in a vehicle-mounted camera. It can be attached to and detached from the camera body (not shown) of an in-vehicle camera. The lens unit 10 forms an image of the incident light on an image sensor surface (not shown) within the camera body. Note that the lens unit 10 may be used for other cameras such as a surveillance camera instead of being used for an in-vehicle camera.

(Telescope barrel 12)
1, the lens unit 10 includes a substantially cylindrical lens barrel 12 that extends in the optical axis direction. The tip side of the lens barrel 12 faces the object side (subject side), and the base side of the lens barrel 12 faces the image side. Both the tip side and the base side of the lens barrel 12 are open.
The lens barrel 12 has a first tube portion 12a located closest to the object, a second tube portion 12b located next to the first tube portion 12a on the object side, and a third tube portion 12c located closest to the image side. The inner diameter of the first tube portion 12a of the lens barrel 12 is larger than the inner diameters of the second tube portion 12b and the third tube portion 12c. The inner diameter of the second tube portion 12b of the lens barrel 12 is larger than the inner diameter of the third tube portion 12c. The lens barrel 12 is made of a synthetic resin, such as polyphenylene sulfide (PPS) resin.

(First lens 14, second lens 16, third lens 18)
As shown in FIG. 1, inside the lens barrel 12, a first lens 14, a second lens 16, and a third lens 18 are provided along the optical axis direction. In other words, a lens group consisting of a plurality of lenses 14, 16, and 18 is provided within the lens barrel 12. In other words, the lens barrel 12 accommodates a lens group consisting of a plurality of lenses 14, 16, and 18.

The first lens 14 is housed so as to fit into the first cylindrical portion 12a of the lens barrel 12. The first lens 14 is located closest to the object side among the plurality of lenses 14, 16, and 18. The outer diameter of the first lens 14 is slightly smaller than the inner diameter of the first cylindrical portion 12a of the lens barrel 12. The outer diameter of the first lens 14 is larger than the outer diameter of the second lens 16 and the outer diameter of the third lens 18. In other words, the first lens 14 has the largest outer diameter among the plurality of lenses 14, 16, and 18. The first lens 14 has a convex surface 14a on the object side and a concave surface 14b on the image side. The first lens 14 is made of glass or plastic.

The second lens 16 is accommodated in the second cylindrical portion 12b of the lens barrel 12 so as to fit into it. The second lens 16 is adjacent to the first lens 14 in the optical axis direction while in contact with it, and is located closer to the image side than the first lens 14. The outer diameter of the second lens 16 is slightly smaller than the inner diameter of the second cylindrical portion 12b of the lens barrel 12. The outer diameter of the second lens 16 is larger than the outer diameter of the third lens 18. The second lens 16 has a concave surface 16a on the object side and a concave surface 16b on the image side. The second lens 16 is made of glass or plastic.

The third lens 18 is accommodated in the third tube portion 12c of the lens barrel 12 so as to fit into it. The third lens 18 is adjacent to the second lens 16 in the optical axis direction while being spaced apart from it, and is located closest to the image side when they are interposed. The outer diameter of the third lens 18 is slightly smaller than the inner diameter of the third tube portion 12c of the lens barrel 12. The outer diameter of the third lens 18 is smaller than the outer diameter of the first lens 14 and the outer diameter of the second lens 16. In other words, the third lens 18 has the smallest outer diameter of the multiple lenses 14, 16, and 18. The third lens 18 has a convex surface 18a on the object side and a concave surface 18b on the image side. The third lens 18 is made of glass or plastic.

Note that the number of lenses 14, 16, and 18 constituting the lens group is not limited to three, and may be two or four or more. Moreover, an anti-reflection film, a hydrophilic film, a water-repellent film, etc. may be formed on the surfaces of the plurality of lenses 14, 16, and 18, respectively, if necessary.

(First spacer 20, second spacer 22)
As shown in FIG. 1, an annular first spacer 20 is provided between the second lens 16 and the third lens 18 in the lens barrel 12. In other words, the annular first spacer 20 is fitted and housed in the third barrel portion 12c of the lens barrel 12, and the first spacer 20 is arranged between the second lens 16 and the third lens 18. It is located in between. The first spacer 20 is slightly smaller than the inner diameter of the third cylindrical portion 12c of the lens barrel 12. The first spacer 20 is made of, for example, synthetic resin such as polyphenylene sulfide resin.

A second annular spacer 22 is provided within the lens barrel 12 on the image side of the third lens 18 . In other words, the annular second spacer 22 is fitted and accommodated in the third barrel portion 12c of the lens barrel 12, and the second spacer 22 is in contact with the third lens 18 when the third lens 18 is in contact with the second spacer 22. It is located closer to the image side than the lens 18. The second spacer 22 is made of, for example, synthetic resin such as polyphenylene sulfide resin.

Note that the number of spacers 20 and 22 is not limited to two, and may be one. In other words, one annular spacer may be provided between any of the plurality of lenses 14, 16, and 18 that are adjacent in the optical axis direction, if necessary.

(Flange part 24, caulking part 26)
As shown in FIG. 1, an annular flange portion (protrusion) 26 that protrudes radially inward is formed on the base end side of the lens barrel 12, and the flange portion 24 is a part of the lens barrel 12. be. The flange portion 24 is engaged with the peripheral edge of the image-side surface of the second spacer 22 . In other words, the flange portion 24 is engaged with the peripheral edge of the image-side surface of the third lens 18 via the second spacer 22 . The flange portion 24 positions the plurality of lenses 14 , 16 , 18 in the optical axis direction within the lens barrel 12 .

An annular caulked portion 26 is formed on the distal end side of the lens barrel 12 and is caulked so as to cover the peripheral edge of the object side surface of the first lens 14 . It is. The caulking portion 26 cooperates with the flange portion 24 to sandwich the plurality of lenses 14, 16, 18 and the plurality of spacers 20, 22. In other words, the caulking portion 26 cooperates with the flange portion 24 to fix the plurality of lenses 14 , 16 , 18 and the plurality of spacers 20 , 22 to the lens barrel 12 .

(Other optical parts)
A disk-shaped optical filter (not shown) is provided on the image side of the flange portion 24 of the lens barrel 12 to remove light of a predetermined frequency component (for example, light in the near-infrared region). Furthermore, an annular diaphragm member is provided between any of the plurality of lenses 14, 16, and 18 adjacent to each other in the optical axis direction to limit the amount of light passing therethrough.

(O-ring 28, housing groove 30)
As shown in FIG. 1, IIA in FIG. 2, and IIB in FIG. An annular accommodation groove 30 is formed for accommodating the. The O-ring 28 is configured to be crushed in the optical axis direction between the first lens 14 and the lens barrel 12 by forming the caulked portion 26 . The O-ring 28 is configured to seal the inside of the lens barrel 12 by being crushed in the optical axis direction between the first lens 14 and the lens barrel 12 . Thereby, the O-ring 28 interposed between the first lens 14 and the lens barrel 12 can add a waterproof function to the lens unit 10.

(Positioning groove 32)
As shown in FIG. 1, IIA in FIG. 2, and IIB in FIG. 2, an annular positioning groove 32 for positioning the O-ring 28 is formed in the bottom surface 30b of the housing groove 30. The positioning groove 32 has a V-shaped cross section. The groove center of the positioning groove 32 is located at the same position as the groove center of the accommodation groove 30.

The distance K (predetermined distance K) between one wall surface 30f of the storage groove 30 and one edge 32e of the positioning groove 32 and the distance S (predetermined distance S) between the other wall surface 30s of the storage groove 30 and the other edge 32v of the positioning groove 32 are set to the same distance. Note that the predetermined distance K and the predetermined distance K may be different distances.

The predetermined interval K and the predetermined interval S are each set to be 1/5 or more and less than half the wire diameter D of the O-ring 28. The reason why the predetermined interval K and the predetermined interval S are each set to be 1/5 or more of the wire diameter D of the O-ring 28 is that if the predetermined interval K and the predetermined interval S are less than 1/5 of the wire diameter D of the O-ring 28, the width W will be wide and the depth H will be relatively small, which may impair the centering action described below. The reason why the predetermined interval K and the predetermined interval S are each set to be less than half the wire diameter D of the O-ring 28 is to exert the centering action described below. The wire diameter of the O-ring 28 refers to the diameter (thickness) of the O-ring 28 in the cross section of the O-ring.

The width dimension W of the positioning groove 32 is set to be 10% or more and 200% or less of the wire diameter D of the O-ring 28. The reason why the width W of the positioning groove 32 is set to 10% or more of the wire diameter D of the O-ring 28 is because if the width W of the positioning groove 32 is less than 10% of the wire diameter D of the O-ring 28, the O-ring This is because there is a concern that the volume of the portion of 28 that fits into the positioning groove 32 will decrease, and the positioning performance of the positioning groove 32 will deteriorate. The reason why the width W of the positioning groove 32 is set to 200% or less of the wire diameter D of the O-ring 28 is because if the width W of the positioning groove 32 exceeds 200% of the wire diameter D of the O-ring 28, the width W This is because if the depth H becomes relatively too small, the centering effect, which will be described later, will be impaired. Further, the lens barrel 12 expands in the radial direction (radial direction of the lens barrel 12), which impedes miniaturization of the lens unit 10.

The depth dimension H of the positioning groove 32 is set to 5% or more and 50% or less of the wire diameter D of the O-ring 28. The reason why the depth dimension H of the positioning groove 32 is set to 5% or more of the wire diameter D of the O-ring 28 is that if the depth dimension H of the positioning groove 32 is less than 5% of the wire diameter D of the O-ring 28, the volume of the part of the O-ring 28 that fits into the positioning groove 32 will be small, and there is a concern that the positioning performance of the positioning groove 32 will be reduced. The reason why the depth dimension H of the positioning groove 32 is set to 50% or less is that if the depth dimension H of the positioning groove 32 exceeds 50%, the accommodation groove 30 will be narrowed as a result, and the filling rate of the O-ring 28 will be too high compared to the volume of the accommodation groove 30.

Instead of being V-shaped, the cross-sectional shape of the positioning groove 32 may be rectangular as shown in FIG. 3A, or may be trapezoidal as shown in FIG. 3B. In addition, instead of being V-shaped, the cross-sectional shape of the positioning groove 32 may be U-shaped as shown in FIG. 4IVA.

As shown in IVB of FIG. 4, by forming two annular positioning protrusions 34 and 36 on the bottom surface 30b of the accommodation groove 30, the positioning groove 32 can be formed between the two positioning protrusions 34 and 36. good. In other words, the positioning groove 32 may be formed on the bottom surface 30b of the housing groove 30 via the two positioning protrusions 34 and 36.

(effect)
Next, the effects of the first embodiment will be described with reference to FIGS. 1, 2, and 5. FIG. 5 is a schematic cross-sectional view for explaining some of the effects of the first embodiment.

In the lens unit 10, the annular positioning groove 32 is formed in the bottom surface 30b of the housing groove 30, as described above. Therefore, when a plurality of lenses 14, 16, 18 are interposed in the lens barrel 12, the O-ring 28 is positioned at a predetermined position in the housing groove 30 to eliminate or reduce the bias of the reaction force of the O-ring 28. be able to. Therefore, according to the first embodiment, when the O-ring 28 is interposed between the first lens 14 and the lens barrel 12, misalignment and lens tilt of the plurality of lenses 14, 16, 18 are suppressed, and the lens The quality of the unit 10 can be improved.

In the configuration of the lens unit 10, as described above, the predetermined interval K and the predetermined interval S are each set to be less than half the wire diameter D of the O-ring 28. Therefore, when the O-ring 28 is inserted into the accommodation groove 30, the center of the O-ring 28 will be located on the positioning groove 32. Therefore, as shown in FIG. 5, even if the O-ring 28 is inserted into the accommodation groove 30 in a biased state, when a pressing load F is applied to the O-ring 28 from the first lens 14 side, the center of the O-ring 28 will be A centering action is exerted to bring the O-ring 28 closer to the center of the positioning groove 32, and the O-ring 28 moves in the direction of arrow A. Thereby, when assembling the plurality of lenses 14, 16, 18 into the lens barrel 12, the O-ring 28 is positioned at a predetermined position in the housing groove 30 so that the center of the O-ring 28 is located at the center of the positioning groove 32. As a result, the bias of the reaction force of the O-ring 28 can be eliminated or sufficiently reduced. Therefore, according to the first embodiment, lens tilt can be further suppressed and the quality of the lens unit 10 can be further improved.

In the lens unit 10, as described above, the width dimension W of the positioning groove 32 is set to be 10% or more and 200% or less of the wire diameter D of the O-ring 28. Therefore, while reducing the size of the lens unit 10, a sufficient volume of the portion of the O-ring 28 that fits into the positioning groove 32 can be ensured, and the positioning performance of the positioning groove 32 can be improved.

In the lens unit 10, as described above, the depth dimension H of the positioning groove 32 is set to be 5% or more and 50% or less of the wire diameter D of the O-ring 28. Therefore, a sufficient volume of the portion of the O-ring 28 that fits into the positioning groove 32 can be ensured, and the positioning performance of the positioning groove 32 can be improved.

[Embodiment 2]
With reference to FIG. 6, the configuration of the lens unit according to the second embodiment will be described. FIG. 6 is a schematic cross-sectional view of the lens unit according to the second embodiment along the optical axis direction.

(Overview of lens unit 38)
As shown in FIG. 6, the lens unit 38 according to the second embodiment is an optical unit used for a vehicle-mounted camera, and forms an image of incident light on an image sensor surface (not shown) in the camera body. The lens unit 38 has the same configuration as the lens unit 10 according to the first embodiment (see FIG. 1), except for a part. Of the configuration of the lens unit 38, only the points that are different from the configuration of the lens unit 10 will be described. For convenience of explanation, members having the same functions as those described in Embodiment 1 will be denoted by the same reference numerals, and the description thereof will not be repeated.

(Stepped portion 14d, male threaded portion 40)
As shown in FIG. 6, an annular stepped portion 14d is provided at the peripheral edge of the object-side surface of the first lens 14. Further, a male threaded portion 40 is formed from the outer circumferential surface of the first cylindrical portion 12a of the lens barrel 12 to the outer circumferential surface of the second cylindrical portion 12b. In other words, the male threaded portion 40 is formed on the outer circumferential surface of the lens barrel 12 on the distal end side.

(Retaining ring 42, female screw part 44, pressing part 46)
As shown in FIG. 6, a presser ring 42 that presses the first lens 14 toward the image side is screwed onto the distal end side of the lens barrel 12. A female threaded portion 44 is formed on the inner circumferential surface of the holding ring 42 and is threaded into the male threaded portion 40 of the lens barrel 12 . Further, an annular pressing portion 46 is formed on the tip side (object side) of the holding ring 42 to press the stepped portion 14d of the first lens 14 toward the image side. The holding ring 42 cooperates with the flange portion 24 to sandwich the plurality of lenses 14, 16, 18 and the plurality of spacers 20, 22. In other words, the holding ring 42 cooperates with the flange portion 24 to fix the plurality of lenses 14 , 16 , 18 and the plurality of spacers 20 , 22 to the lens barrel 12 .

(O-ring 28)
The O-ring 28 is configured to be crushed in the optical axis direction between the first lens 14 and the lens barrel 12 when the first lens 14 is pressed by the holding ring 42 . The O-ring 28 is configured to seal the inside of the lens barrel 12 by being crushed in the optical axis direction between the first lens 14 and the lens barrel 12 . Thereby, the O-ring 28 interposed between the first lens 14 and the lens barrel 12 can add a waterproof function to the lens unit 38.

(effect)
As described above, the lens unit 38 has the same configuration as the lens unit 10 according to the first embodiment. Therefore, the second embodiment also provides the same effects as those of the first embodiment described above.

〔summary〕
A lens unit according to aspect 1 of the present invention includes a lens barrel and a plurality of lenses provided in the lens barrel along an optical axis direction, and is a part of the lens barrel and includes a plurality of lenses. An annular accommodation groove for accommodating an O-ring is formed in a portion facing the peripheral edge of the image-side surface of the lens closest to the object side of the lenses, and the O-ring is connected to the lens closest to the object side. An annular ring for positioning the O-ring is configured to seal the inside of the lens barrel by being crushed in the optical axis direction between the lens barrel and the housing groove. A positioning groove is formed.

According to the above configuration, as described above, the annular positioning groove is formed on the bottom surface of the accommodation groove. Therefore, when assembling the plurality of lenses to the lens barrel, it is possible to position the O-ring at a predetermined position in the housing groove, thereby eliminating or reducing the bias of the reaction force of the O-ring. As a result, when the O-ring is interposed between the lens closest to the object side and the lens barrel, it is possible to suppress misalignment and lens tilt of the plurality of lenses and improve the quality of the lens unit. can.

In the lens unit according to Aspect 2 of the present invention, in Aspect 1, the distance between one wall surface of the accommodation groove and one end edge of the positioning groove, and the distance between the other wall surface of the accommodation groove and the other edge of the positioning groove. The distance from the end edge of each of the O-rings may be set to be less than half the wire diameter of the O-ring.

According to the above configuration, when the O-ring is inserted into the accommodation groove, the center of the O-ring is located on the positioning groove, and a centering action that brings the center of the O-ring to the center of the positioning groove is performed. Demonstrated. Thereby, when assembling the plurality of lenses to the lens barrel, the O-ring is positioned at a predetermined position in the accommodation groove so that the center of the O-ring is located at the center of the positioning groove, and the O-ring is positioned at a predetermined position in the accommodation groove. The bias of the reaction force of the ring can be eliminated or sufficiently reduced.

In the lens unit according to aspect 3 of the present invention, in aspect 1 or 2, the width dimension of the positioning groove may be set to be 10% or more and 200% or less of the wire diameter of the O-ring.

According to the above-mentioned configuration, it is possible to reduce the size of the lens unit while ensuring a sufficient volume of the portion of the O-ring that fits into the positioning groove, thereby improving the positioning performance of the positioning groove.

In the lens unit according to aspect 4 of the present invention, in any one of aspects 1 to 3, the depth dimension of the positioning groove may be set to 5% or more and 50% or less of the wire diameter of the O-ring. good.

According to the above configuration, a sufficient volume of the portion of the O-ring that fits into the positioning groove can be ensured, and the positioning performance of the positioning groove can be improved.

In the lens unit according to aspect 5 of the present invention, in any one of aspects 1 to 4, the lens unit is caulked on the distal end side of the lens barrel so as to cover the peripheral edge of the object side surface of the lens closest to the object side. A caulking portion may be formed, and the O-ring may be configured to be crushed in the optical axis direction between the lens closest to the object side and the lens barrel by forming the caulking portion.

According to the above configuration, a waterproof function can be added to the lens unit by the O-ring interposed between the lens closest to the object side and the lens barrel.

The lens unit according to aspect 6 of the present invention is provided in any one of aspects 1 to 4 by being screwed onto the distal end side of the lens barrel, and the lens closest to the object side is placed on the image side (one side in the optical axis direction). The O-ring further includes a presser ring that presses the lens closest to the object side), and the O-ring is configured to press the lens closest to the object side by the presser ring, so that the lens closest to the object side is pressed between the lens closest to the object side and the lens barrel in the optical axis direction. It may be configured to be crushed.

According to the above configuration, a waterproof function can be added to the lens unit by the O-ring interposed between the lens closest to the object and the lens barrel.

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

10 Lens unit 12 Lens barrel 12a First cylinder portion 12b Second cylinder portion 12c Third cylinder portion 14 First lens 14a Convex surface 14b Concave surface 16 Second lens 16a Concave surface 16b Concave surface 18 Third lens 18a Convex surface 18b Concave surface 20 First spacer 22 Second spacer 24 Flange portion 26 Crimping portion 28 O-ring 30 Housing groove 30b Bottom surface 30f One wall surface 30s The other wall surface 32 Positioning groove 32e One edge 32v The other edge 34 Positioning protrusion 36 Positioning protrusion 38 Lens unit 40 Male thread portion 42 Pressing ring 44 Female thread portion 46 Pressing portion

Claims (6)

lens barrel and
a plurality of lenses provided in the lens barrel along the optical axis direction,
An annular accommodation groove for accommodating an O-ring is formed in a part of the lens barrel and facing a peripheral edge of an image-side surface of the lens closest to the object of the plurality of lenses. ,
The O-ring is configured to seal the inside of the lens barrel by being crushed in the optical axis direction between the lens closest to the object side and the lens barrel,
A lens unit, wherein an annular positioning groove for positioning the O-ring is formed on a bottom surface of the housing groove. The lens unit according to claim 1, wherein the distance between one wall surface of the housing groove and one edge of the positioning groove, and the distance between the other wall surface of the housing groove and the other edge of the positioning groove are each set to less than half the wire diameter of the O-ring. The lens unit according to claim 1, wherein the width dimension of the positioning groove is set to be 10% or more and 200% or less of the wire diameter of the O-ring. The lens unit according to claim 1, wherein the depth dimension of the positioning groove is set to be 5% or more and 50% or less of the wire diameter of the O-ring. An annular caulked portion is formed on the distal end side of the lens barrel so as to cover the peripheral edge of the object side surface of the lens closest to the object side,
The lens unit according to claim 1, wherein the O-ring is configured to be crushed in the optical axis direction between the lens closest to the object side and the lens barrel by forming the caulked portion. . further comprising a presser ring that is screwed onto the tip side of the lens barrel and presses the lens closest to the object side toward the image side;
The O-ring is configured to be crushed in the optical axis direction between the lens closest to the object and the lens barrel when the lens closest to the object is pressed by the presser ring. The lens unit according to claim 1.

Images