CN117270137A - Lens unit - Google Patents

Abstract

The challenge is to reduce the size of the lens unit and improve the durability of the lens unit. A solution is that the holder (38) has an annular pressing portion (42) that presses the plurality of lenses (14, 16, 18, 20, 22). An annular recessed portion (44) that is recessed toward one side in the optical axis direction is formed on the radially outer side of the pressing portion (42) in the holder (38). In a cross section along the optical axis direction, the recessed portion (44) is ) is formed into a curved shape.

Description

lens unit

Technical field

The present invention relates to lens units.

Background technique

As a lens unit used for a camera such as a vehicle-mounted camera, there is a lens unit shown in Patent Document 1. The lens unit according to this prior art is provided with a substantially cylindrical lens barrel (an inner barrel called a first resin lens barrel in Patent Document 1) extending in the optical axis direction. In the lens barrel, a plurality of lenses are provided along the optical axis direction. An annular holder (referred to as a second resin lens barrel in Patent Document 1) that fixes a plurality of lenses to the lens barrel is provided on the proximal end side of the outer peripheral wall of the lens barrel in a threaded manner. The holder has an annular pressing part (referred to as a holding part in Patent Document 1) that presses the plurality of lenses from one side (one side) in the optical axis direction.

Prior technical documents

patent documents

Patent Document 1: Japanese Patent No. 5686171

Contents of the invention

The problem to be solved by the invention

In addition, a lens unit used in a vehicle-mounted camera is used in a wide temperature range of -40°C to 120°C, for example. In order to stably hold multiple lenses in the lens barrel in this wide temperature range, it is necessary to increase the tightening force of the holder to increase the pressing force of the pressing portion.

However, if the tightening force of the holder is increased, cracks may occur due to excessive stress concentration around the pressing portion, resulting in reduced durability of the lens unit. On the other hand, if the distance from the inner circumferential surface of the pressing part to the outer circumferential surface of the holder is increased to increase the strength of the holder in order to suppress stress concentration around the pressing part, the radial dimension of the lens unit will be enlarged. This leads to an increase in the size of the lens unit.

Therefore, one aspect of the present invention aims to reduce the size of the lens unit and improve the durability of the lens unit.

Means used to solve problems

In order to solve the above problem, one aspect of the present invention includes: a lens barrel; a plurality of lenses arranged in the lens barrel along the optical axis direction; and an annular holder arranged to be threadedly engaged with the lens barrel and having an opposite direction. An annular pressing portion for pressing the plurality of lenses fixes the plurality of lenses with respect to the lens barrel. An annular recessed portion that is recessed toward one side (one side) in the optical axis direction is formed on the radially outer side of the pressing portion in the holder. In a cross section along the optical axis direction, The recess is formed in a curved shape.

Invention effect

According to one aspect of the present invention, the lens unit can be miniaturized and the durability of the lens unit can be improved.

Description of the drawings

FIG. 1 is a schematic cross-sectional view along the optical axis direction of the lens unit according to Embodiment 1.

FIG. 2 is an enlarged cross-sectional view of portion II in FIG. 1 .

FIG. 3 is a partially enlarged cross-sectional view of the lens unit according to another aspect of Embodiment 1. FIG.

4 is a schematic cross-sectional view along the optical axis direction of the lens unit according to Embodiment 2.

FIG. 5 is an enlarged cross-sectional view of the V portion in FIG. 4 .

6 is a schematic cross-sectional view along the optical axis direction of the lens unit according to Embodiment 3.

FIG. 7 is an enlarged cross-sectional view of portion VI in FIG. 6 .

Detailed ways

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Furthermore, in the specification and claims, the optical axis direction refers to the optical axis direction of the lens, the optical axis direction of the lens barrel, or the optical axis direction of the lens unit. The optical axis direction has the same meaning as the axial direction of the lens barrel or the axial direction of the lens unit, and is the front-to-back direction in the embodiment of the present invention. The radial direction is the radial direction of the lens, the radial direction of the lens barrel, or the radial direction of the lens unit. The radially outer side refers to the direction away from the optical axis (center line of the lens or lens unit) in the radial direction, and the radial inner side refers to the direction closer to the optical axis in the radial direction. In the drawings, "AD" refers to the optical axis direction, "RDo" refers to the radially outside, "RDi" refers to the radially inside, "FF" refers to the front side or front direction, and "FR" Refers to the back side or rear direction.

[Embodiment 1]

The structure of the lens unit 10 according to Embodiment 1 will be described with reference to FIGS. 1 and 2 . FIG. 1 is a schematic cross-sectional view along the optical axis direction of the lens unit 10 according to Embodiment 1. FIG. 2 is an enlarged cross-sectional view of portion II in FIG. 1 .

(Outline of lens unit 10)

As shown in FIG. 1 , the lens unit 10 according to Embodiment 1 is an optical unit used for a vehicle-mounted camera. It is detachable from the camera body (not shown) of the vehicle-mounted camera. The lens unit 10 forms an image of incident light onto an imaging element surface (not shown) in the camera body. Furthermore, the lens unit 10 may be used not for a vehicle-mounted camera but for other cameras such as a surveillance camera.

(lens tube 12)

As shown in FIG. 1 , the lens unit 10 includes a substantially cylindrical lens barrel 12 extending in the optical axis direction. The front end side, which is the distal end side of the lens barrel 12, and the rear end side, which is the proximal end side of the lens barrel 12, are each open. The lens barrel 12 is made of synthetic resin such as polyphenylene sulfide (PPS) resin. The distal end side of the lens barrel 12 faces the subject (object) side, and the base end side of the lens barrel 12 faces the imaging side.

(Multiple lenses 14, 16, 18, 20, 22)

As shown in FIG. 1 , in the lens barrel 12 , the first lens 14 , the second lens 16 , the third lens 18 , the fourth lens 20 and the fifth lens 22 are provided along the optical axis direction. In other words, a lens group composed of a plurality of lenses 14 , 16 , 18 , 20 , and 22 is provided in the lens barrel 12 . In other words, the lens barrel 12 accommodates a lens group composed of a plurality of lenses 14 , 16 , 18 , 20 , and 22 .

The first lens 14 is located on the distal end side (front end side) of the lens barrel 12 and is made of glass or plastic. One lens surface 14 a and the other lens surface 14 b of the first lens 14 are each formed in a planar shape perpendicular to the optical axis direction. The peripheral edges of the two lens surfaces 14a and 14b of the first lens 14 are each chamfered. In addition, one of the two lens surfaces 14a and 14b of the first lens 14 may be formed into a convex curved surface or a concave curved surface.

The second lens 16 and the first lens 14 are adjacent in the optical axis direction in a contact state, and are made of glass or plastic. One lens surface 16 a and the other lens surface 16 b of the second lens 16 are each formed in a planar shape perpendicular to the optical axis direction. The peripheral edges of the two lens surfaces 16a and 16b of the second lens 16 are each chamfered. One of the two lens surfaces 16a and 16b of the second lens 16 may be formed into a convex curved surface or a concave curved surface.

The third lens 18 and the second lens 16 are spaced apart and adjacent to each other in the optical axis direction, and are made of glass or plastic. One lens surface 18 a and the other lens surface 18 b of the third lens 18 are each formed in a planar shape perpendicular to the optical axis direction. In addition, any one of the one lens surface 18 a and the other lens surface 18 b of the third lens 18 may be formed in a convex curved surface shape or a concave curved surface shape.

The fourth lens 20 and the third lens 18 are spaced apart and adjacent to each other in the optical axis direction, and are made of glass or plastic. One lens surface 20 a and the other lens surface 20 b of the fourth lens 20 are each formed in a planar shape perpendicular to the optical axis direction. The peripheral edges of the two lens surfaces 20a and 20b of the fourth lens 20 are each chamfered. In addition, the two lens surfaces 20a of the fourth lens 20 may be formed in a convex curved surface shape or a concave curved surface shape.

The fifth lens 22 is located on the proximal end side (rear end side) of the lens barrel 12 and is adjacent to the fourth lens 20 in the optical axis direction in a spaced state. The fifth lens 22 is made of glass or plastic. One lens surface 22a of the fifth lens 22 is formed in a convex curved surface. The other lens surface 22b of the fifth lens 22 is formed in a planar shape perpendicular to the optical axis direction. The peripheral edge of the other lens surface 22b of the fifth lens 22 is chamfered. In addition, the other lens surface 22b of the fifth lens 22 may be formed into a convex curved surface or a concave curved surface.

The plurality of lenses 14, 16, 18, 20, and 22 are positioned in the radial direction relative to the lens barrel 12 by a plurality of positioning ribs (not shown) formed on the inner peripheral wall 12i of the lens barrel 12. The centers of the plurality of lenses 14, 16, 18, 20, and 22 are respectively aligned with the optical axis. In addition, on the two lens surfaces 14a, 14b, 16a, 16b, 18a, 18b, 20a, 20b, 22a, and 22b of the plurality of lenses 14, 16, 18, 20, and 22, an antireflection film and an anti-reflection film are formed respectively as necessary. Water film, water repellent film, etc.

(Plural spacers 24, 26, 28)

As shown in FIG. 1 , an annular first spacer 24 is provided between the second lens 16 and the third lens 18 in the lens barrel 12 . The first spacer 24 is made of synthetic resin such as polyphenylene sulfide resin. The first spacer 24 has an annular holding surface 24g that holds the outer edge portion of the second lens 16 on its front side (front side). The first spacer 24 has an annular holding surface 24p that holds the outer edge portion of the third lens 18 on its back side (rear side).

An annular second spacer 26 is provided between the third lens 18 and the fourth lens 20 in the lens barrel 12 . The second spacer 26 is made of synthetic resin such as polyphenylene sulfide resin. The second spacer 26 has an annular holding surface 26g on its front side that holds the outer edge portion of the third lens 18. The second spacer 26 has an annular holding surface 26p on its back side that holds the outer edge portion of the fourth lens 20.

An annular third spacer 28 is provided between the fourth lens 20 and the fifth lens 22 in the lens barrel 12 . The third spacer 28 is made of synthetic resin such as polyphenylene sulfide resin, for example. The third spacer 28 has an annular holding surface 28g on its front side that holds the outer edge portion of the fourth lens 20 . The third spacer 28 has an annular holding surface 28p on its back side that holds the outer edge portion of the fifth lens 22 .

The plurality of spacers 24 , 26 , 28 are positioned in the radial direction relative to the lens barrel 12 by a plurality of positioning ribs of the lens barrel 12 .

(Filter holding member 30, infrared cut filter 32)

A ring-shaped filter (optical filter) holding member 30 is provided on the rear side of the fifth lens 22 in the lens barrel 12 . The filter holding member 30 is made of synthetic resin such as polyphenylene sulfide resin. In addition, a disk-shaped infrared cut filter 32 that removes light in the near-infrared region is provided as an optical filter on the back surface of the filter holding member 30 . In addition, another optical filter that removes light of a predetermined frequency component may be used instead of the infrared cut filter 32 . In addition, an annular diaphragm member (not shown) that limits the amount of passing light is provided between any of the plurality of lenses 14, 16, 18, 20, and 22 adjacent in the optical axis direction.

(Protruding portion 34, external thread portion 36)

As shown in FIG. 1 , an annular protrusion 34 protruding radially inward is formed on the distal end side (front end side) of the inner peripheral wall 12 i of the lens barrel 12 . The protruding portion 34 is engaged with the outer edge portion of the first lens 14 from the front direction to position the plurality of lenses 14 , 16 , 18 , 20 , and 22 relative to the lens barrel 12 in the optical axis direction. A male thread portion 36 is formed on the base end side (rear end side) of the outer peripheral wall 12 o of the lens barrel 12 .

(Retainer 38, internal thread part 40, pressing part 42)

As shown in FIGS. 1 and 2 , an annular holder 38 for fixing the plurality of lenses 14 , 16 , 18 , 20 , and 22 relative to the lens barrel 12 is provided on the outer peripheral wall 12 o of the lens barrel 12 in a threaded manner. Basal side. An internal thread portion 40 for threading engagement with the external thread portion 36 of the lens barrel 12 is formed on the inner peripheral surface of the holder 38 . The holder 38 is made of synthetic resin such as polyphenylene sulfide resin. In addition, the holder 38 has an annular pressing portion 42 that presses the plurality of lenses 14, 16, 18, 20, and 22 toward the protruding portion 34 from one side (one side) of the optical axis direction. 42 can be elastically deformed. The pressing part 42 clamps the infrared cut filter 32 in cooperation with the filter holding member 30 . The pressing part 42 presses the plurality of lenses 14, 16, 18, 20, and 22 from the rear direction toward the protruding part 34 via the infrared cut filter 32, the filter holding member 30, and the plurality of spacers 24, 26, and 28.

The tip surface 42t of the pressing portion 42 is a surface that contacts the peripheral edge portion of the infrared cut filter 32 and is a pressing surface that presses the plurality of lenses 14, 16, 18, 20, and 22 toward the protruding portion 34 side. The tip surface 42t of the pressing part 42 is orthogonal to the optical axis direction. In a cross section along the optical axis direction, the inner peripheral surface 42i of the pressing portion 42 is inclined relative to the optical axis direction so as to be located radially outward as the distance from the tip surface 42t increases. In other words, in a cross section along the optical axis direction, the inner peripheral surface 42i of the pressing portion 42 is inclined relative to the optical axis direction so as to be located radially inward as it approaches the tip surface 42t.

According to the above-mentioned structure, by fastening the holder 38 , the pressing part 42 pushes the plurality of lenses 14 , 16 , 18 , 20 , 22 from the rear direction on one side which is the direction of the optical axis via the plurality of spacers 24 , 26 , 28 . The protruding portion 34 side is pressed. Thereby, the plurality of lenses 14 , 16 , 18 , 20 , and 22 can be fixed relative to the lens barrel 12 and stably held in the lens barrel 12 .

(recess 44)

As shown in FIGS. 1 and 2 , an annular recessed portion is formed on the radially outer side of the tip surface 42t of the pressing portion 42 in the holder 38 and is recessed toward the rear direction of one side (one side) in the direction of the optical axis. 44. The recessed portion 44 is formed in a shape curved in an arc shape in a cross section along the optical axis direction. The recess 44 has one or more radii of curvature. The radius of curvature of the recessed portion 44 is set to 0.3 mm or more, for example. When the recessed portion 44 has a plurality of curvature radii, the curvature radius of the recessed portion 44 is the average curvature radius. The radial width W of the recess 44 is longer than the radial length of the base end surface (rear end surface) of the lens barrel 12 . In order to suppress the radial expansion of the lens unit 10 , the radial width W of the recessed portion 44 is set to 2 mm or less, for example. The length L in the optical axis direction from the top surface of the pressing part 42 to the bottom of the recessed part 44 is set to 0.6 mm or more, for example.

(Effect)

According to the structure of the lens unit 10 , as described above, the recessed portion 44 is formed in a shape curved in an arc shape in a cross section along the optical axis direction. Therefore, even if the distance from the inner circumferential surface 42i of the pressing part 42 to the outer circumferential surface 38o of the holder 38 is increased without increasing the tightening force of the holder 38, the surrounding areas of the pressing part 42 including the recessed part 44 can be suppressed. stress concentration. As a result, the lens unit 10 can be miniaturized, cracks can be prevented around the pressing portion 42 , and the durability of the lens unit 10 can be improved.

In addition, according to the structure of the lens unit 10 , as described above, in a cross section along the optical axis direction, the inner peripheral surface 42 i of the pressing portion 42 is located radially outward as the distance from the tip surface 42 t of the pressing portion 42 increases. Tilt relative to the optical axis. Therefore, the pressing part 42 is easily flexible, and the pressing force (axial force) of the pressing part 42 in the optical axis direction can be stably maintained in a wide temperature range from low temperature to high temperature. Specifically, when the thermal expansion coefficient of the lens barrel 12 is larger than that of the lens 14 or the like, the pressing force in the optical axis direction of the pressing portion 42 tends to decrease at high temperatures and increase at low temperatures. When the thermal expansion coefficient of the lens barrel 12 is smaller than that of the lens 14 or the like, the pressing force in the optical axis direction of the pressing portion 42 tends to increase at high temperatures and decrease at low temperatures. Therefore, by firmly fastening the holder 38 with the pressing portion 42 bent at normal temperature, the pressing force of the pressing portion 42 in the optical axis direction can be stably maintained in a wide temperature range from low temperature to high temperature.

[Other aspects of Embodiment 1]

The structure of the lens unit 10A according to another aspect of Embodiment 1 will be described with reference to FIG. 3 . FIG. 3 is a partially enlarged cross-sectional view of the lens unit 10A according to another aspect of Embodiment 1.

(Outline of lens unit 10A)

As shown in FIG. 3 , a lens unit 10A according to another aspect of Embodiment 1 is an optical unit used for a vehicle-mounted camera, and forms an image of incident light on an imaging element surface (not shown) in the camera body. The lens unit 10A has the same structure as the lens unit 10 according to Embodiment 1 (see FIG. 2 ) except for a part. Only the differences between the structure of the lens unit 10A and the structure of the lens unit 10 will be described. In addition, for convenience of explanation, components having the same functions as those described in the present embodiment are denoted by the same reference numerals, and description thereof will not be repeated.

(First curved portion 44a, second curved portion 44b, straight portion 44c)

As shown in FIG. 3 , the recessed portion 44 is formed in a curved shape in a cross section along the optical axis direction. The recessed portion 44 has a first curved portion 44a located radially inside and curved in an arc shape, a second curved portion 44b located radially outside and curved in an arc shape, and a first curved portion 44a and a second curved portion located between the radially outer side and the first curved portion 44a. The straight portion 44c between 44b. The meaning of the curved shape includes a case where a part has a straight portion 44c.

The first curved portion 44a of the recessed portion 44 is adjacent to the pressing portion 42 and has one or more curvature radii. The curvature radius of the first curved portion 44a of the recessed portion 44 is set to 0.3 mm or more, for example. The second curved portion 44b of the recessed portion 44 has one or more curvature radii. The curvature radius of the second curved portion 44b of the recessed portion 44 is set to 0.3 mm or more, for example. The straight portion 44c of the recessed portion 44 is smoothly connected to the first curved portion 44a and the second curved portion 44b.

(Effect)

Next, the operation and effect of other aspects of Embodiment 1 will be described.

In the lens unit 10A, as described above, the recessed portion 44 has the straight portion 44c located between the first curved portion 44a and the second curved portion 44b. Therefore, in the cross section along the optical axis direction, the radial width of the recessed portion 44 can be shortened compared with the case where the recessed portion 44 is formed in an arc shape. Accordingly, the size reduction of the lens unit 10A can be promoted in accordance with the shortening of the radial width of the recessed portion 44 .

In addition, the same functions and effects as those of Embodiment 1 can also be achieved in other aspects of Embodiment 1.

[Embodiment 2]

The structure of the lens unit 46 according to Embodiment 2 will be described with reference to FIGS. 4 and 5 . FIG. 4 is a schematic cross-sectional view along the optical axis direction of the lens unit 46 according to Embodiment 2. FIG. 5 is an enlarged cross-sectional view of the V portion in FIG. 4 .

(Outline of lens unit 46)

As shown in FIG. 4 , the lens unit 46 according to Embodiment 2 is an optical unit used for a vehicle-mounted camera, and forms an image of incident light on an imaging element surface (not shown) in the camera body. The lens unit 46 has the same structure as the lens unit 10 according to Embodiment 1 (see FIGS. 1 and 2 ) except for a part. Only the differences between the structure of the lens unit 46 and the structure of the lens unit 10 will be described. In addition, for convenience of explanation, components having the same functions as those described in the present embodiment are denoted by the same reference numerals, and description thereof will not be repeated.

(Female thread part 48, holder 50, external thread part 52, pressing part 54)

As shown in FIGS. 4 and 5 , an internal thread portion 48 is formed on the base end side (rear end side) of the outer peripheral wall 12 o of the lens barrel 12 . An annular holder 50 for fixing the plurality of lenses 14 , 16 , 18 , 20 , and 22 to the lens barrel 12 is threadedly provided on the base end side of the inner peripheral wall 12 i of the lens barrel 12 . An external thread portion 52 for threading engagement with the internal thread portion 48 of the lens barrel 12 is formed on the outer peripheral surface of the holder 50 . The holder 50 is made of synthetic resin such as polyphenylene sulfide resin. In addition, the holder 50 has an annular pressing portion 54 that presses the plurality of lenses 14, 16, 18, 20, and 22 toward the protruding portion 34 from one side (one side) of the optical axis direction. 54 can be elastically deformed. The pressing part 54 clamps the infrared cut filter 32 in cooperation with the filter holding member 30 . The pressing part 54 presses the plurality of lenses 14, 16, 18, 20, and 22 from the rear direction toward the protruding part 34 via the infrared cut filter 32, the filter holding member 30, and the plurality of spacers 24, 26, and 28.

The tip surface 54t of the pressing portion 54 is a surface that contacts the peripheral edge of the infrared cut filter 32 and is a pressing surface that presses the plurality of lenses 14, 16, 18, 20, and 22 toward the protruding portion 34 side. The tip surface 54t of the pressing part 54 is orthogonal to the optical axis direction. In a cross section along the optical axis direction, the inner peripheral surface 54i of the pressing portion 54 is inclined relative to the optical axis direction so as to be located radially outward as the distance from the tip surface 54t increases. In other words, in a cross section along the optical axis direction, the inner peripheral surface 54i of the pressing portion 54 is inclined relative to the optical axis direction so as to be located radially inward as it approaches the tip surface 54t.

According to the above-mentioned structure, by fastening the holder 50 , the pressing portion 54 pushes the plurality of lenses 14 , 16 , 18 , 20 , 22 from the rear direction on one side as the optical axis direction via the plurality of spacers 24 , 26 , 28 . The protruding portion 34 side is pressed. Thereby, the plurality of lenses 14 , 16 , 18 , 20 , and 22 can be fixed relative to the lens barrel 12 and stably held in the lens barrel 12 .

(recess 56)

As shown in FIGS. 4 and 5 , an annular recessed portion is formed on the radially outer side of the tip surface 54t of the pressing portion 54 in the holder 50 and is recessed in the rear direction of one side (one side) in the direction of the optical axis. 44. In a cross section along the optical axis direction, the recessed portion 56 is formed in a curved shape, specifically a U-shape, and is expanded toward the opening side. In other words, the recessed portion 56 has a first straight portion located radially inside, a second straight portion located radially outside, and a curved portion located between the first straight portion and the second straight portion and curved in an arc shape. The radius of curvature of the bottom of the recess 56 is set to 0.3 mm or more, for example. In order to suppress the radial expansion of the lens unit 46 , the radial width W of the recessed portion 56 is set to 2 mm or less, for example. The length L in the optical axis direction from the top surface of the pressing part 54 to the bottom of the recessed part 56 is set to 0.6 mm or more, for example.

(Effect)

Next, the operation and effect of Embodiment 2 will be described.

According to the structure of the lens unit 46 , as described above, the recessed portion 56 is formed in a shape curved in an arc shape in a cross section along the optical axis direction. Therefore, even if the tightening force of the holder 50 is increased without increasing the distance from the inner peripheral surface 54i of the pressing part 54 to the outer peripheral surface 50o of the holder 50, it is possible to suppress the surrounding areas of the pressing part 54 including the recessed part 56. stress concentration. This allows the lens unit 46 to be miniaturized, prevents cracks from occurring around the pressing portion 54 , and improves the durability of the lens unit 46 .

In particular, in the cross section along the optical axis direction, the recessed portion 56 is formed in a U shape and expands toward the opening side. Therefore, in the cross section along the optical axis direction, the radial width of the recessed portion 56 can be shortened compared with the case where the recessed portion 56 is formed in an arc shape. Accordingly, the size reduction of the lens unit 46 can be promoted in accordance with the shortening of the radial width of the recessed portion 56 .

In addition, according to the structure of the lens unit 46, as described above, in a cross section along the optical axis direction, the inner peripheral surface 54i of the pressing portion 54 is positioned radially outward with respect to the optical axis as it is farther away from the tip surface 54t. The direction is tilted. Therefore, the pressing portion 54 is easily deflected, and the pressing force of the pressing portion 54 in the optical axis direction can be stably maintained in a wide temperature range from low temperature to high temperature.

[Embodiment 3]

The structure of the lens unit 58 according to Embodiment 3 will be described with reference to FIGS. 6 and 7 . FIG. 6 is a schematic cross-sectional view along the optical axis direction of the lens unit 58 according to Embodiment 3. FIG. 7 is an enlarged cross-sectional view of portion VII in FIG. 6 .

(Outline of lens unit 58)

As shown in FIG. 6 , the lens unit 58 according to Embodiment 3 is an optical unit used for a vehicle-mounted camera, and forms an image of incident light on an imaging element surface (not shown) in the camera body. The lens unit 58 has the same structure as the lens unit 10 according to Embodiment 1 (see FIGS. 1 and 2 ) except for a part. Only the differences between the structure of the lens unit 58 and the structure of the lens unit 10 will be described. In addition, for convenience of explanation, components having the same functions as those described in the present embodiment are denoted by the same reference numerals, and description thereof will not be repeated.

(Protruding portion 60, external thread portion 62)

As shown in FIG. 6 , an annular protrusion 60 protruding radially inward is formed on the base end side (rear end side) of the inner peripheral wall 12 i of the lens barrel 12 . The protrusion 60 is engaged with the outer edge of the infrared cut filter 32 from the rear direction to position the plurality of lenses 14 , 16 , 18 , 20 , and 22 relative to the lens barrel 12 in the optical axis direction. A male thread portion 62 is formed on the distal end side (front end side) of the outer peripheral wall 12 o of the lens barrel 12 .

(Holder 64, Female Thread Part 66, Pressing Part 68)

As shown in FIGS. 6 and 7 , an annular holder 64 for fixing the plurality of lenses 14 , 16 , 18 , 20 , and 22 relative to the lens barrel 12 is provided on the outer peripheral wall 12 o of the lens barrel 12 in a threaded manner. Top side. An internal thread portion 66 for threading engagement with the external thread portion 62 of the lens barrel 12 is formed on the inner peripheral surface of the holder 64 . The holder 64 is made of synthetic resin such as polyphenylene sulfide resin. In addition, the holder 64 has an annular pressing portion 68 that presses the plurality of lenses 14, 16, 18, 20, and 22 toward the protruding portion 34 from the front direction of one side (one side) as the optical axis direction. 68 can be elastically deformed. The pressing portion 68 presses the plurality of lenses 14, 16, 18, 20, and 22 from the front toward the protruding portion 60 via the plurality of spacers 24, 26, and 28, the infrared cut filter 32, and the filter holding member 30.

The tip surface 68t of the pressing portion 68 is a surface that contacts the peripheral portion of the first lens 14 and is a pressing surface that presses the plurality of lenses 14, 16, 18, 20, and 22 toward the protruding portion 60 side. The tip surface 68t of the pressing part 68 is orthogonal to the optical axis direction. In a cross section along the optical axis direction, the inner peripheral surface 68i of the pressing portion 68 is inclined relative to the optical axis direction so as to be located radially outward as the distance from the tip surface 68t increases. In other words, in a cross section along the optical axis direction, the inner peripheral surface 68i of the pressing portion 68 is inclined relative to the optical axis direction so as to be located radially inward as it approaches the tip surface 68t.

According to the above structure, by fastening the holder 64 , the pressing portion 68 pushes the plurality of lenses 14 , 16 , 18 , 20 , 22 from the front direction on one side which is the optical axis direction via the plurality of spacers 24 , 26 , 28 . The protruding portion 60 side is pressed. Thereby, the plurality of lenses 14 , 16 , 18 , 20 , and 22 can be fixed relative to the lens barrel 12 and stably held in the lens barrel 12 .

(recess 70)

As shown in FIGS. 6 and 7 , an annular recessed portion that is recessed in the forward direction of one side (one side) that is the direction of the optical axis is formed radially outside the tip surface 68t of the pressing portion 68 in the holder 64 . 70. The recess 70 is formed in a shape curved in an arc shape in a cross section along the optical axis direction. The recess 70 has one or more radii of curvature. The curvature radius of the recessed portion 70 is set to 0.3 mm or more, for example. When the recessed portion 70 has a plurality of curvature radii, the curvature radius of the recessed portion 70 is the average curvature radius. The radial width W of the recess 70 is longer than the radial length of the top end surface (front end surface) of the lens barrel 12 . In order to suppress the radial expansion of the lens unit 58 , the radial width W of the recessed portion 70 is set to 2 mm or less, for example. The length L in the optical axis direction from the top surface of the pressing part 68 to the bottom of the recessed part 70 is set to 0.6 mm or more, for example.

(Effect)

Next, the operation and effect of Embodiment 3 will be described.

According to the structure of the lens unit 58 , as described above, the recessed portion 70 is formed in a shape curved in an arc shape in a cross section along the optical axis direction. Therefore, even if the distance from the inner circumferential surface 68i of the pressing part 68 to the outer circumferential surface 64o of the holder 64 is not increased and the tightening force of the holder 64 is increased, the surrounding areas of the pressing part 68 including the recessed part 70 can be suppressed. stress concentration. Thereby, the lens unit 58 can be miniaturized, cracks can be prevented around the pressing portion 68 , and the durability of the lens unit 58 can be improved.

In addition, according to the structure of the lens unit 58, as described above, in a cross section along the optical axis direction, the inner peripheral surface 68i of the pressing portion 68 is located radially outward with respect to the optical axis as it is farther away from the tip surface 68t. The direction is tilted. Therefore, the pressing portion 68 is easily deflected, and the pressing force of the pressing portion 68 in the optical axis direction can be stably maintained in a wide temperature range from low temperature to high temperature.

[Other embodiments]

Although illustration is omitted, in the lens unit 10 , the protruding portion 34 may be omitted, and an annular intermediate protruding portion protruding radially inward may be formed in the middle portion of the inner peripheral wall 12 i of the lens barrel 12 . In this case, the pressing portion 42 of the holder 38 presses the plurality of lenses 20 and 22 toward the intermediate protrusion portion from the rear direction. In addition, an annular second holder for fixing the plurality of lenses 14 , 16 , 18 , 20 , and 22 to the lens barrel 12 is provided on the front end side of the outer peripheral wall 12 o of the lens barrel 12 . The second holder has a second pressing portion that presses the plurality of lenses 14, 16, and 18 toward the intermediate protruding portion from the front direction. The second holder has the same structure as the holder 64 of the lens unit 58 .

〔Summarize〕

A lens unit according to the first aspect of the present invention includes: a lens barrel; a plurality of lenses arranged in the lens barrel along the optical axis direction; and an annular holder arranged to be threadedly engaged with the lens barrel and having an opposite direction. An annular pressing portion for pressing the plurality of lenses fixes the plurality of lenses with respect to the lens barrel. An annular recessed portion that is recessed toward one side (one side) in the optical axis direction is formed on the radially outer side of the pressing portion in the holder. In a cross section along the optical axis direction, The recess is formed in a curved shape.

According to the above structure, as described above, the recessed portion is formed in a curved shape in a cross section along the optical axis direction. Therefore, even if the distance from the inner circumferential surface of the pressing part to the outer circumferential surface of the holder is not increased and the tightening force of the holder is increased, the pressing force including the recessed part can be suppressed. Stress concentration at the periphery. As a result, the lens unit can be miniaturized, cracks can be prevented around the pressing portion, and the durability of the lens unit can be improved.

The lens unit according to the second aspect of the present invention may be such that in the first aspect, in a cross section along the optical axis direction, the inner surface of the pressing portion is oriented so as to extend beyond the top surface of the pressing portion. The direction farther away from the optical axis is tilted relative to the direction of the optical axis.

According to the above-mentioned structure, the pressing part is easy to flex, and the pressing force of the pressing part in the optical axis direction can be stably maintained in a wide temperature range from low temperature to high temperature.

The lens unit according to the third aspect of the present invention in the first or second aspect may further include an annular spacer provided in the optical axis direction among the plurality of lenses. Between any adjacent lenses, an annular protruding portion protruding radially inward is formed on the inner peripheral wall of the lens barrel, and the pressing portion presses the plurality of lenses toward the protruding portion side.

According to the above structure, by tightening the holder, the pressing portion presses the plurality of lenses toward the protruding portion via the spacer. Thereby, the plurality of lenses can be fixed relative to the lens barrel and stably held in the lens barrel.

In the lens unit according to the fourth aspect of the present invention, in the first or second aspect, an annular protruding portion protruding radially inward may be formed on the tip side of the inner peripheral wall of the lens barrel, and the The holder is provided to be threadedly engaged with the proximal end side of the outer peripheral wall of the lens barrel, and the pressing part presses the plurality of lenses toward the protruding part side.

According to the above-described structure, by tightening the holder, the pressing portion presses the plurality of lenses toward the protruding portion. Thereby, the plurality of lenses can be fixed relative to the lens barrel and stably held in the lens barrel.

In the lens unit according to the fifth aspect of the present invention, in the first or second aspect, an annular protruding portion protruding radially inward may be formed on the tip side of the inner peripheral wall of the lens barrel, and the The holder is provided to be threadedly engaged with the proximal end side of the inner peripheral wall of the lens barrel, and the pressing part presses the plurality of lenses toward the protruding part side.

According to the above-described structure, by tightening the holder, the pressing portion presses the plurality of lenses toward the protruding portion. Thereby, the plurality of lenses can be fixed relative to the lens barrel and stably held in the lens barrel.

In the lens unit according to the sixth aspect of the present invention, in the first or second aspect, an annular protrusion protruding radially inward may be formed on the proximal end side of the inner peripheral wall of the lens barrel,

The holder is provided to be threadedly engaged with a distal end side of the outer peripheral wall of the lens barrel, and the pressing part presses the plurality of lenses toward the protruding part side.

According to the above-described structure, by tightening the holder, the pressing portion presses the plurality of lenses toward the protruding portion. Thereby, the plurality of lenses can be fixed relative to the lens barrel and stably held in the lens barrel.

In the lens unit according to aspect 7 of the present invention, in any one of aspects 1 to 6, in a cross section along the optical axis direction, the recessed portion may have a shape located radially inward and curved. A first curved portion, a second curved portion located radially outward and curved, and a straight portion located between the first curved portion and the second curved portion.

According to the above-described configuration, in a cross section along the optical axis direction, the radial width of the recessed portion can be shortened compared with a case where the recessed portion is formed in an arc shape. Thereby, it is possible to promote the downsizing of the lens unit in accordance with the shortening of the radial width of the recessed portion.

In the lens unit according to the eighth aspect of the present invention, in any one of the first to sixth aspects, the recess may be formed in a U-shape in a cross section along the optical axis direction.

According to the above-described configuration, in a cross section along the optical axis direction, the radial width of the recessed portion can be shortened compared with a case where the recessed portion is formed in an arc shape. Thereby, it is possible to promote the downsizing of the lens unit in accordance with the shortening of the radial width of the recessed portion.

[Additional Notes]

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

Explanation of reference signs

10 Lens unit (lens unit according to Embodiment 1)

12 lens barrel

12i inner peripheral wall

12o peripheral wall

14 1st lens

16 second lens

18 3rd lens

20 4th lens

22 5th lens

24 1st spacer

26 2nd spacer

28 3rd spacer

30 filter holding parts

32 Infrared cut filter

34 protrusion

36 External thread part

38 retainer

38o outer surface

40 Internal thread part

42 Compression part

42t top surface

42i inner surface

44 recess

10A lens unit (lens unit according to other aspects of Embodiment 1)

44a 1st bend

44b 2nd bending part

44c straight part

46 lens unit (lens unit according to Embodiment 2)

48 Internal thread part

50 retainer

50o outer surface

52 External thread part

54 Compression part

54t top surface

54i inner surface

56 recess

58 lens unit (lens unit according to Embodiment 3)

60 protrusion

62 External thread part

64 retainer

64o outer surface

66 Internal thread part

68 Compression part

68t top surface

68i inner surface

70 recess

Claims (8)

1. A lens unit having: Lens barrel; A plurality of lenses are arranged in the lens barrel along the optical axis direction; and An annular holder is provided to be threadedly engaged with the lens barrel, has an annular pressing portion for pressing the plurality of lenses, and fixes the plurality of lenses relative to the lens barrel, An annular recessed portion that is recessed toward one side in the optical axis direction is formed on the radially outer side of the pressing portion in the holder. In a cross section along the optical axis direction, the recessed portion forms For curved shape. 2. The lens unit according to claim 1, In a cross section along the optical axis direction, the inner surface of the pressing portion is inclined with respect to the optical axis direction so as to be located radially outward as the distance from the tip surface of the pressing portion increases. 3. The lens unit according to claim 1, The lens unit further includes: an annular spacer provided between any lenses adjacent in the optical axis direction among the plurality of lenses, An annular protrusion protruding radially inward is formed on the inner peripheral wall of the lens barrel, The pressing part presses the plurality of lenses toward the protruding part side. 4. The lens unit according to claim 1, An annular protrusion protruding radially inward is formed on the top end side of the inner peripheral wall of the lens barrel, The holder is provided to be threadedly engaged with the proximal end side of the outer peripheral wall of the lens barrel, and the pressing part presses the plurality of lenses toward the protruding part side. 5. The lens unit of claim 1, An annular protrusion protruding radially inward is formed on the top end side of the inner peripheral wall of the lens barrel, The holder is provided to be threadedly engaged with the proximal end side of the inner peripheral wall of the lens barrel, and the pressing portion presses the plurality of lenses toward the protruding portion. 6. The lens unit of claim 1, An annular protrusion protruding radially inward is formed on the base end side of the inner peripheral wall of the lens barrel, The holder is provided to be threadedly engaged with a distal end side of the outer peripheral wall of the lens barrel, and the pressing part presses the plurality of lenses toward the protruding part side. 7. The lens unit of claim 1, In a cross section along the optical axis direction, the recessed portion has a first curved portion located radially inward and curved, a second curved portion located radially outer and curved, and a curved portion located between the first curved portion and the first curved portion. The straight portion between the second curved portions. 8. The lens unit of claim 1, The recess is formed in a U shape in a cross section along the optical axis direction.