CN117270137A

CN117270137A - Lens unit

Info

Publication number: CN117270137A
Application number: CN202310566813.6A
Authority: CN
Inventors: 井上道夫
Original assignee: Tamron Co Ltd
Current assignee: Tamron Co Ltd
Priority date: 2022-06-22
Filing date: 2023-05-19
Publication date: 2023-12-22
Also published as: JP2024001703A

Abstract

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

Description

Lens unit

Technical Field

The present invention relates to a lens unit.

Background

As a lens unit for a camera such as an in-vehicle camera, there is a lens unit shown in patent document 1. The lens unit according to the related art includes a substantially cylindrical barrel (referred to as an inner barrel of a first resin barrel in patent document 1), and the barrel extends in the optical axis direction. A plurality of lenses are provided in the lens barrel along the optical axis direction. An annular holder (referred to as a second resin barrel in patent document 1) for fixing a plurality of lenses to the barrel is provided on the base end side of the outer peripheral wall of the barrel in a threaded manner. The holder has an annular pressing portion (referred to as a holding portion in patent document 1) that presses the plurality of lenses from one side (one side) in the optical axis direction.

Prior art literature

Patent literature

Patent document 1: japanese patent No. 5686171

Disclosure of Invention

Problems to be solved by the invention

In addition, a lens unit for an in-vehicle camera is used in a wide temperature range of-40 to 120 ℃. In order to stably hold a plurality of lenses in the lens barrel in this wide temperature range, it is necessary to increase the fastening force of the holder to increase the pressing force of the pressing portion.

However, if the fastening force of the holder is increased, cracks are generated due to excessive stress concentration at the periphery of the pressing portion, resulting in a decrease in durability of the lens unit. On the other hand, if the strength of the holder is increased by increasing the distance from the inner peripheral surface of the pressing portion to the outer peripheral surface of the holder in order to suppress the concentration of stress at the periphery of the pressing portion, the radial dimension of the lens unit is enlarged, resulting in an increase in the size of the lens unit.

Accordingly, an object of one embodiment of the present invention is to achieve downsizing of a lens unit and to improve durability of the lens unit.

Means for solving the problems

In order to achieve the above object, one embodiment of the present invention includes: a lens barrel; a plurality of lenses disposed in the barrel along an optical axis direction; and an annular retainer provided in threaded engagement with the lens barrel and having an annular pressing portion for pressing the plurality of lenses, the annular retainer fixing the plurality of lenses to the lens barrel. An annular concave portion recessed toward one side (one side) in the optical axis direction is formed radially outward of the pressing portion in the holder, and the concave portion is formed in a curved shape in a cross section along the optical axis direction.

Effects of the invention

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

Drawings

Fig. 1 is a schematic cross-sectional view of a lens unit according to embodiment 1 along an optical axis direction.

Fig. 2 is an enlarged sectional view of the portion II in fig. 1.

Fig. 3 is a partially enlarged cross-sectional view of a lens unit according to another embodiment of embodiment 1.

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

Fig. 5 is an enlarged sectional view of the V portion in fig. 4.

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

Fig. 7 is an enlarged sectional view of the VI portion in fig. 6.

Detailed Description

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

[ embodiment 1 ]

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

(outline of lens Unit 10)

As shown in fig. 1, a lens unit 10 according to embodiment 1 is an optical unit for a vehicle-mounted camera. Can be attached to and detached from a camera body (not shown) of the in-vehicle camera. The lens unit 10 forms an image of incident light on an image pickup element surface (not shown) in the camera body. The lens unit 10 may be used for other cameras such as a monitoring camera, instead of the in-vehicle camera.

(lens barrel 12)

As shown in fig. 1, the lens unit 10 includes a substantially cylindrical barrel 12, and the barrel 12 extends in the optical axis direction. The front end side, which is the tip end side of the lens barrel 12, and the rear end side, which is the base end side of the lens barrel 12, are respectively opened. The lens barrel 12 is made of synthetic resin such as polyphenylene sulfide (PPS) resin, for example. The tip 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 1 st lens 14, the 2 nd lens 16, the 3 rd lens 18, the 4 th lens 20, and the 5 th lens 22 are provided along the optical axis direction. In other words, a lens group including a plurality of lenses 14, 16, 18, 20, 22 is provided in the lens barrel 12. In other words, the lens barrel 12 accommodates a lens group constituted by a plurality of lenses 14, 16, 18, 20, 22.

The 1 st lens 14 is located on the tip end side (front end side) in the barrel 12, and the 1 st lens 14 is made of glass or plastic. One lens surface 14a and the other lens surface 14b of the 1 st lens 14 are each formed in a plane shape perpendicular to the optical axis direction. Chamfering is applied to each of the peripheral edges of the 2 lens surfaces 14a, 14b of the 1 st lens 14. In addition, one of the 2 lens surfaces 14a and 14b of the 1 st lens 14 may be formed in a convex curved surface shape or a concave curved surface shape.

The 2 nd lens 16 is adjacent to the 1 st lens 14 in the optical axis direction in a contact state, and is made of glass or plastic. One lens surface 16a and the other lens surface 16b of the 2 nd lens 16 are each formed in a plane shape perpendicular to the optical axis direction. Chamfering is applied to each peripheral edge of the 2 nd lens 16 at the 2 nd lens faces 16a, 16 b. One of the 2 nd lens 16 may be formed in a convex curved surface or a concave curved surface of the 2 nd lens surfaces 16a and 16 b.

The 3 rd lens 18 and the 2 nd lens 16 are adjacent to each other in the optical axis direction in a state of being isolated, and are made of glass or plastic. One lens surface 18a and the other lens surface 18b of the 3 rd lens 18 are each formed in a plane shape perpendicular to the optical axis direction. Either one of the lens surface 18a and the other lens surface 18b of the 3 rd lens 18 may be formed in a convex curved surface shape or a concave curved surface shape.

The 4 th lens 20 and the 3 rd lens 18 are adjacent to each other in the optical axis direction in a state of being isolated from each other, and are made of glass or plastic. One lens surface 20a and the other lens surface 20b of the 4 th lens 20 are each formed in a plane shape perpendicular to the optical axis direction. Chamfering is applied to each of the peripheral edges of the 2 lens surfaces 20a, 20b of the 4 th lens 20. The 2 lens surfaces 20a of the 4 th lens 20 may be formed in a convex curved surface shape or a concave curved surface shape.

The 5 th lens 22 is located on the base end side (rear end side) within the barrel 12, and is adjacent to the 4 th lens 20 in the optical axis direction in a state of being separated. The 5 th lens 22 is made of glass or plastic. One lens surface 22a of the 5 th lens 22 is formed in a convex curved surface shape. The other lens surface 22b of the 5 th lens 22 is formed in a plane shape perpendicular to the optical axis direction. Chamfering is applied to the peripheral edge of the other lens surface 22b of the 5 th lens 22. The other lens surface 22b of the 5 th lens 22 may be formed in a convex curved surface or a concave curved surface.

The plurality of lenses 14, 16, 18, 20, 22 are positioned in the radial direction with respect 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, 22 respectively coincide with the optical axes. Further, antireflection films, hydrophilic films, water repellent films, and the like are formed on 2 lens surfaces 14a, 14b, 16a, 16b, 18a, 18b, 20a, 20b, 22a, 22b of the plurality of lenses 14, 16, 18, 20, 22, as necessary.

(multiple spacers 24, 26, 28)

As shown in fig. 1, an annular 1 st spacer 24 is provided between the 2 nd lens 16 and the 3 rd lens 18 in the barrel 12. The 1 st spacer 24 is made of a synthetic resin such as polyphenylene sulfide resin, for example. The 1 st spacer 24 has an annular holding surface 24g on the front side (front side) thereof for holding the outer edge portion of the 2 nd lens 16. The 1 st spacer 24 has an annular holding surface 24p on the back surface side (rear side) thereof for holding the outer edge portion of the 3 rd lens 18.

An annular 2 nd spacer 26 is provided between the 3 rd lens 18 and the 4 th lens 20 in the barrel 12. The 2 nd spacer 26 is made of a synthetic resin such as polyphenylene sulfide resin, for example. The 2 nd spacer 26 has an annular holding surface 26g on the front side thereof for holding the outer edge portion of the 3 rd lens 18. The 2 nd spacer 26 has an annular holding surface 26p on the back surface side thereof for holding the outer edge portion of the 4 th lens 20.

An annular 3 rd spacer 28 is provided between the 4 th lens 20 and the 5 th lens 22 in the barrel 12. The 3 rd spacer 28 is made of a synthetic resin such as polyphenylene sulfide resin, for example. The 3 rd spacer 28 has an annular holding surface 28g on the front side thereof for holding the outer edge portion of the 4 th lens 20. The 3 rd spacer 28 has an annular holding surface 28p on the back surface side thereof for holding the outer edge portion of the 5 th lens 22.

The plurality of spacers 24, 26, 28 are positioned radially with respect to the barrel 12 by the plurality of positioning ribs of the barrel 12.

(Filter holding Member 30, infrared cut Filter 32)

A ring-shaped filter (filter) holding member 30 is provided on the rear side of the 5 th lens 22 in the barrel 12. The filter holding member 30 is made of synthetic resin such as polyphenylene sulfide resin, for example. A disk-shaped infrared cut filter 32 for removing light in the near infrared region is provided as a filter on the back surface of the filter holding member 30. Instead of the infrared cut filter 32, another filter for removing light having a predetermined frequency component may be used. Further, an annular diaphragm member (not shown) for restricting the amount of light passing through is provided between any one of the plurality of lenses 14, 16, 18, 20, 22 adjacent in the optical axis direction.

(protrusion 34, external thread 36)

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

(retainer 38, female screw portion 40, pressing portion 42)

As shown in fig. 1 and 2, an annular holder 38 for fixing the plurality of lenses 14, 16, 18, 20, 22 to the lens barrel 12 is provided on the base end side of the outer peripheral wall 12o of the lens barrel 12 in a screw-threaded manner. A female screw portion 40 for screw-engaging with the male screw 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, for example. The holder 38 has an annular pressing portion 42 that presses the plurality of lenses 14, 16, 18, 20, 22 toward the protruding portion 34 from the rear direction on one side (one side) in the optical axis direction, and the pressing portion 42 is elastically deformable. The pressing portion 42 holds the infrared cut filter 32 by cooperation with the filter holding member 30. The pressing portion 42 presses the plurality of lenses 14, 16, 18, 20, 22 toward the protrusion 34 from the rear direction via the infrared cut filter 32, the filter holding member 30, and the plurality of spacers 24, 26, 28.

The distal end 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, 22 toward the protruding portion 34. The tip surface 42t of the pressing portion 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 with respect to the optical axis direction so as to be located radially outward as it is further away from the distal end surface 42 t. In other words, in a cross section along the optical axis direction, the inner peripheral surface 42i of the pressing portion 42 is inclined with respect to the optical axis direction so as to be located radially inward as approaching the tip end surface 42 t.

According to the above-described configuration, the pressing portion 42 presses the plurality of lenses 14, 16, 18, 20, 22 toward the protruding portion 34 from the rear direction, which is the one side in the optical axis direction, via the plurality of spacers 24, 26, 28 by tightening the holder 38. This makes it possible to fix the plurality of lenses 14, 16, 18, 20, 22 to the lens barrel 12 and stably hold them in the lens barrel 12.

(recess 44)

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

(effects of action)

According to the structure of the lens unit 10, as described above, in the cross section along the optical axis direction, the concave portion 44 is formed in a shape curved in an arc shape. Therefore, even if the fastening force of the holder 38 is increased without increasing the distance from the inner peripheral surface 42i of the pressing portion 42 to the outer peripheral surface 38o of the holder 38, the stress concentration at the periphery of the pressing portion 42 including the concave portion 44 can be suppressed. Thereby, miniaturization of the lens unit 10 can be achieved, and occurrence of cracks at the periphery of the pressing portion 42 can be prevented, improving durability of the lens unit 10.

In addition, according to the configuration of the lens unit 10, as described above, in the cross section along the optical axis direction, the inner peripheral surface 42i of the pressing portion 42 is inclined with respect to the optical axis direction so as to be located radially outward as it is farther from the distal end surface 42t of the pressing portion 42. Therefore, the pressing portion 42 is easily deflected, and the pressing force (axial force) in the optical axis direction of the pressing portion 42 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 a high temperature and to increase at a low temperature. 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 a high temperature and decrease at a low temperature. Therefore, by firmly fastening the holder 38 in a state where the pressing portion 42 is bent at normal temperature, the pressing force in the optical axis direction of the pressing portion 42 can be stably maintained in a wide temperature range from low temperature to high temperature.

[ other modes of embodiment 1 ]

A configuration of a lens unit 10A according to another embodiment of embodiment 1 will be described with reference to fig. 3. Fig. 3 is a partially enlarged cross-sectional view of a lens unit 10A according to another embodiment of embodiment 1.

(outline of lens unit 10A)

As shown in fig. 3, a lens unit 10A according to another embodiment of embodiment 1 is an optical unit for a vehicle-mounted camera, and images incident light on an imaging element surface (not shown) in a camera body. The lens unit 10A has the same configuration as the lens unit 10 (see fig. 2) according to embodiment 1 except for a part thereof. Only points different from the structure of the lens unit 10 among the structures of the lens unit 10A are described. For convenience of explanation, the same reference numerals are given to members having the same functions as those described in the present embodiment, and the explanation thereof will not be repeated.

(1 st curved portion 44a, 2 nd curved portion 44b, straight portion 44 c)

As shown in fig. 3, in a cross section along the optical axis direction, the concave portion 44 is formed in a curved shape. The recess 44 has: the 1 st curved portion 44a located radially inward and curved in an arc shape, the 2 nd curved portion 44b located radially outward and curved in an arc shape, and the straight line portion 44c located between the 1 st curved portion 44a and the 2 nd curved portion 44 b. The meaning of the curved shape includes a case where a part has the straight line portion 44c.

The 1 st curved portion 44a of the concave portion 44 is adjacent to the pressing portion 42, and has 1 or more radii of curvature. The radius of curvature of the 1 st curved portion 44a of the concave portion 44 is set to, for example, 0.3mm or more. The 2 nd curved portion 44b of the concave portion 44 has 1 or more radii of curvature. The radius of curvature of the 2 nd curved portion 44b of the concave portion 44 is set to, for example, 0.3mm or more. The straight portion 44c of the concave portion 44 is smoothly connected to the 1 st curved portion 44a and the 2 nd curved portion 44 b.

(effects of action)

Next, the operational effects of the other modes of embodiment 1 will be described.

In the lens unit 10A, as described above, the concave portion 44 has the straight line portion 44c located between the 1 st curved portion 44a and the 2 nd curved portion 44 b. Therefore, the width of the concave portion 44 in the radial direction can be shortened in the cross section along the optical axis direction as compared with the case where the concave portion 44 is formed in an arc shape. Accordingly, the downsizing of the lens unit 10A can be promoted by the amount of the reduction in the width of the recess 44 in the radial direction.

In addition, the other embodiments of embodiment 1 can also have the same operational effects as those of embodiment 1.

[ embodiment 2 ]

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

(outline of lens Unit 46)

As shown in fig. 4, a lens unit 46 according to embodiment 2 is an optical unit for a vehicle-mounted camera, and forms an image of incident light on an image pickup device surface (not shown) in a camera body. The lens unit 46 has the same configuration as the lens unit 10 (see fig. 1 and 2) according to embodiment 1 except for a part thereof. Only points different from the structure of the lens unit 10 among the structures of the lens unit 46 are described. For convenience of explanation, the same reference numerals are given to members having the same functions as those described in the present embodiment, and the explanation thereof will not be repeated.

(female screw portion 48, holder 50, male screw portion 52, pressing portion 54)

As shown in fig. 4 and 5, a female screw portion 48 is formed on the base end side (rear end side) of the outer peripheral wall 12o of the lens barrel 12. An annular holder 50, which fixes the plurality of lenses 14, 16, 18, 20, 22 to the lens barrel 12, is provided on the base end side of the inner peripheral wall 12i of the lens barrel 12 in a threaded engagement. A male screw portion 52 for screw-engaging with the female screw 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, for example. The holder 50 has an annular pressing portion 54 that presses the plurality of lenses 14, 16, 18, 20, 22 toward the protruding portion 34 from the rear direction on one side (one side) in the optical axis direction, and the pressing portion 54 is elastically deformable. The pressing portion 54 sandwiches the infrared cut filter 32 by cooperation with the filter holding member 30. The pressing portion 54 presses the plurality of lenses 14, 16, 18, 20, 22 toward the protrusion 34 from the rear direction via the infrared cut filter 32, the filter holding member 30, and the plurality of spacers 24, 26, 28.

The distal end surface 54t of the pressing portion 54 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, 22 toward the protruding portion 34. The tip surface 54t of the pressing portion 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 with respect to the optical axis direction so as to be located radially outward as it is further away from the distal end surface 54 t. In other words, in a cross section along the optical axis direction, the inner peripheral surface 54i of the pressing portion 54 is inclined with respect to the optical axis direction so as to be located radially inward as approaching the tip end surface 54 t.

According to the above-described configuration, by tightening the holder 50, the pressing portion 54 presses the plurality of lenses 14, 16, 18, 20, 22 toward the protruding portion 34 side from the rear direction, which is the one side in the optical axis direction, via the plurality of spacers 24, 26, 28. This makes it possible to fix the plurality of lenses 14, 16, 18, 20, 22 to the lens barrel 12 and stably hold them in the lens barrel 12.

(recess 56)

As shown in fig. 4 and 5, an annular concave portion 44 recessed in the rear direction, which is one side (one side) in the optical axis direction, is formed radially outward of the distal end surface 54t of the pressing portion 54 in the holder 50. In a cross section along the optical axis direction, the concave portion 56 is formed in a curved shape, specifically, in a U-shape, and expands toward the opening side. In other words, the concave portion 56 has a 1 st straight portion located radially inward, a 2 nd straight portion located radially outward, and a curved portion located between the 1 st straight portion and the 2 nd straight portion and curved in an arc shape. The radius of curvature of the bottom of the concave portion 56 is set to, for example, 0.3mm or more. In order to suppress the radial expansion of the lens unit 46, the radial width W of the concave portion 56 is set to, for example, 2mm or less. The length L in the optical axis direction from the top end surface of the pressing portion 54 to the bottom of the concave portion 56 is set to, for example, 0.6mm or more.

(effects of action)

Next, the operational effects of embodiment 2 will be described.

According to the structure of the lens unit 46, as described above, in the cross section along the optical axis direction, the concave portion 56 is formed in a shape curved in an arc shape. Therefore, even if the fastening force of the holder 50 is increased without increasing the distance from the inner peripheral surface 54i of the pressing portion 54 to the outer peripheral surface 50o of the holder 50, the stress concentration at the periphery of the pressing portion 54 including the concave portion 56 can be suppressed. Thereby, miniaturization of the lens unit 46 can be achieved, and occurrence of cracks at the periphery of the pressing portion 54 can be prevented, improving durability of the lens unit 46.

In particular, in a cross section along the optical axis direction, the concave portion 56 is formed in a U shape and is enlarged toward the opening side. Therefore, the width of the concave portion 56 in the radial direction can be shortened in the cross section along the optical axis direction as compared with the case where the concave portion 56 is formed in an arc shape. Accordingly, the downsizing of the lens unit 46 can be promoted by the amount of the reduction in the width of the recess 56 in the radial direction.

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

[ embodiment 3 ]

The configuration of the lens unit 58 according to embodiment 3 will be described with reference to fig. 6 and 7. Fig. 6 is a schematic cross-sectional view of the lens unit 58 according to embodiment 3 along the optical axis direction. Fig. 7 is an enlarged sectional view of the VII in fig. 6.

(outline of lens unit 58)

As shown in fig. 6, a lens unit 58 according to embodiment 3 is an optical unit for a vehicle-mounted camera, and images incident light on an image pickup device surface (not shown) in a camera body. The lens unit 58 has the same configuration as the lens unit 10 (see fig. 1 and 2) according to embodiment 1 except for a part thereof. Only points different from the structure of the lens unit 10 among the structures of the lens unit 58 are described. For convenience of explanation, the same reference numerals are given to members having the same functions as those described in the present embodiment, and the explanation thereof will not be repeated.

(protruding portion 60, external thread portion 62)

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

(retainer 64, female screw portion 66, pressing portion 68)

As shown in fig. 6 and 7, an annular holder 64 for fixing the plurality of lenses 14, 16, 18, 20, 22 to the lens barrel 12 is provided on the tip end side of the outer peripheral wall 12o of the lens barrel 12 in a screw-engaged manner. A female screw portion 66 for screw-engaging with the male screw 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, for example. The holder 64 has an annular pressing portion 68 for pressing the plurality of lenses 14, 16, 18, 20, 22 toward the protruding portion 34 from the front direction on one side (one side) in the optical axis direction, and the pressing portion 68 is elastically deformable. The pressing portion 68 presses the plurality of lenses 14, 16, 18, 20, 22 toward the protruding portion 60 side from the front direction via the plurality of spacers 24, 26, 28, the infrared cut filter 32, and the filter holding member 30.

The distal end surface 68t of the pressing portion 68 is a surface that contacts the peripheral edge portion of the 1 st lens 14, and is a pressing surface that presses the plurality of lenses 14, 16, 18, 20, 22 toward the protruding portion 60. The distal end surface 68t of the pressing portion 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 with respect to the optical axis direction so as to be located radially outward as it is further away from the distal end surface 68 t. In other words, in a cross section along the optical axis direction, the inner peripheral surface 68i of the pressing portion 68 is inclined with respect to the optical axis direction so as to be located radially inward as approaching the tip end surface 68 t.

According to the above-described configuration, the pressing portion 68 presses the plurality of lenses 14, 16, 18, 20, 22 toward the protruding portion 60 from the front direction, which is the one side in the optical axis direction, via the plurality of spacers 24, 26, 28 by tightening the holder 64. This makes it possible to fix the plurality of lenses 14, 16, 18, 20, 22 to the lens barrel 12 and stably hold them in the lens barrel 12.

(recess 70)

As shown in fig. 6 and 7, an annular concave portion 70 recessed in the front direction, which is one side (one side) in the optical axis direction, is formed radially outward of the distal end surface 68t of the pressing portion 68 in the holder 64. In a cross section along the optical axis direction, the concave portion 70 is formed in a shape curved in an arc shape. The recess 70 has 1 or more radii of curvature. The radius of curvature of the concave portion 70 is set to, for example, 0.3mm or more. In the case where the concave portion 70 has a plurality of radii of curvature, the radius of curvature of the concave portion 70 is an average radius of curvature. The width W of the recess 70 in the radial direction is longer than the length of the tip end surface (distal end surface) of the barrel 12 in the radial direction. In order to suppress the radial expansion of the lens unit 58, the radial width W of the concave portion 70 is set to, for example, 2mm or less. The length L in the optical axis direction from the top end surface of the pressing portion 68 to the bottom of the concave portion 70 is set to, for example, 0.6mm or more.

(effects of action)

Next, the operational effects of embodiment 3 will be described.

According to the structure of the lens unit 58, as described above, in the cross section along the optical axis direction, the concave portion 70 is formed in a shape curved in an arc shape. Therefore, even if the fastening force of the holder 64 is increased without increasing the distance from the inner peripheral surface 68i of the pressing portion 68 to the outer peripheral surface 64o of the holder 64, the stress concentration at the periphery of the pressing portion 68 including the concave portion 70 can be suppressed. This can reduce the size of the lens unit 58, prevent cracks from occurring around the pressing portion 68, and improve the durability of the lens unit 58.

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

[ other embodiments ]

Although not shown, the protrusion 34 may be omitted in the lens unit 10, and an annular intermediate protrusion protruding radially inward may be formed in the intermediate portion of the inner peripheral wall 12i of the lens barrel 12. In this case, the pressing portion 42 of the holder 38 presses the plurality of lenses 20, 22 toward the intermediate protruding portion side from the rear direction. Further, an annular 2 nd holder for fixing the plurality of lenses 14, 16, 18, 20, 22 to the lens barrel 12 is provided on the distal end side of the outer peripheral wall 12o of the lens barrel 12. The 2 nd holder has a 2 nd pressing portion that presses the plurality of lenses 14, 16, 18 toward the intermediate protruding portion side from the front direction. The structure of the 2 nd holder is the same as the holder 64 of the lens unit 58.

[ summary ]

A lens unit according to embodiment 1 of the present invention includes: a lens barrel; a plurality of lenses disposed in the barrel along an optical axis direction; and an annular retainer provided in threaded engagement with the lens barrel and having an annular pressing portion for pressing the plurality of lenses, the annular retainer fixing the plurality of lenses to the lens barrel. An annular concave portion recessed toward one side (one side) in the optical axis direction is formed radially outward of the pressing portion in the holder, and the concave portion is formed in a curved shape in a cross section along the optical axis direction.

According to the above configuration, as described above, the concave portion is formed in a curved shape in a cross section along the optical axis direction. Therefore, even if the fastening force of the holder is increased without increasing the distance from the inner peripheral surface of the pressing portion to the outer peripheral surface of the holder, the stress concentration at the periphery of the pressing portion including the concave portion can be suppressed. Thus, the lens unit can be miniaturized, cracks are prevented from occurring at the periphery of the pressing portion, and the durability of the lens unit can be improved.

In the lens unit according to aspect 2 of the present invention, in the aspect 1, the inner surface of the pressing portion may be inclined with respect to the optical axis direction so as to be located radially outward as it is farther from the distal end surface of the pressing portion in a cross section along the optical axis direction.

According to the above configuration, the pressing portion is easily deflected, and the pressing force in the optical axis direction of the pressing portion can be stably maintained in a wide temperature range from low temperature to high temperature.

A lens unit according to embodiment 3 of the present invention may further include, in embodiment 1 or 2: an annular spacer provided between any of the plurality of lenses adjacent in the optical axis direction; an annular projection projecting radially inward is formed on an inner peripheral wall of the lens barrel, and the pressing portion presses the plurality of lenses toward the projection.

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

In the lens unit according to aspect 4 of the present invention, in the aspect 1 or 2, an annular protrusion protruding radially inward may be formed on a distal end side of an inner peripheral wall of the lens barrel, the holder may be provided to be screwed to a proximal end side of an outer peripheral wall of the lens barrel, and the pressing portion may press the plurality of lenses toward the protrusion side.

According to the above configuration, the pressing portion presses the plurality of lenses toward the protruding portion side by fastening the holder. Thereby, the plurality of lenses can be fixed to the lens barrel and stably held in the lens barrel.

In the lens unit according to aspect 5 of the present invention, in the aspect 1 or 2, an annular protrusion protruding radially inward may be formed on a distal end side of the inner peripheral wall of the lens barrel, the holder may be provided to be screwed to a proximal end side of the inner peripheral wall of the lens barrel, and the pressing portion may press the plurality of lenses toward the protrusion side.

In the lens unit according to embodiment 6 of the present invention, in the embodiment 1 or 2, an annular projection portion protruding inward in the radial direction may be formed on the base end side of the inner peripheral wall of the lens barrel,

the holder is provided in threaded engagement with the tip side of the outer peripheral wall of the lens barrel, and the pressing portion presses the plurality of lenses toward the protruding portion side.

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 concave portion may have: a 1 st curved portion located radially inward and curved, a 2 nd curved portion located radially outward and curved, and a straight line portion located between the 1 st curved portion and the 2 nd curved portion.

According to the above configuration, the width of the concave portion in the radial direction can be reduced in the cross section along the optical axis direction as compared with the case where the concave portion is formed in the circular arc shape. Accordingly, the downsizing of the lens unit can be promoted in accordance with the reduction in the width of the concave portion in the radial direction.

In the lens unit according to aspect 8 of the present invention, in any one of aspects 1 to 6, the concave portion may be formed in a U shape in a cross section along the optical axis direction.

[ with record items ]

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

Description of the reference numerals

10 lens unit (lens unit according to embodiment 1)

12. Lens barrel

12i inner peripheral wall

12o peripheral wall

14 1 st lens

16 nd lens

18 3 rd lens

20 th lens

22 th lens

24 1 st spacer

26 nd spacer

28 3 rd spacer

30. Filter holding member

32. Infrared cut-off filter

34. Protruding part

36. External screw thread part

38. Retaining member

38o peripheral surface

40. Internal thread part

42. Pressing part

42t tip end face

42i inner peripheral surface

44. Concave part

10A lens Unit (lens Unit according to other embodiment of embodiment 1)

44a 1 st bend

44b No. 2 bend

44c straight line portion

46 lens unit (lens unit according to embodiment 2)

48. Internal thread part

50. Retaining member

50o peripheral surface

52. External screw thread part

54. Pressing part

54t tip face

54i inner peripheral surface

56. Concave part

58 lens unit (lens unit according to embodiment 3)

60. Protruding part

62. External screw thread part

64. Retaining member

64o peripheral surface

66. Internal thread part

68. Pressing part

68t tip end face

68i inner peripheral surface

70. Concave part

Claims

1. A lens unit is provided with:

a lens barrel;

a plurality of lenses disposed in the barrel along an optical axis direction; and

an annular holder which is provided in threaded engagement with the lens barrel and has an annular pressing portion for pressing the plurality of lenses to fix the plurality of lenses to the lens barrel,

an annular concave portion recessed to one side in the optical axis direction is formed radially outward of the pressing portion in the holder, and the concave portion is formed in a curved shape in a cross section along the optical axis direction.

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 it is farther from the distal end surface of the pressing portion.

3. The lens unit according to claim 1,

the lens unit further includes: an annular spacer provided between any of the plurality of lenses adjacent in the optical axis direction,

an annular protrusion protruding inward in the radial direction is formed on the inner peripheral wall of the lens barrel,

the pressing portion presses the plurality of lenses toward the protruding portion side.

4. The lens unit according to claim 1,

an annular protrusion protruding radially inward is formed on the tip side of the inner peripheral wall of the lens barrel,

the holder is provided in threaded engagement with a base end side of an outer peripheral wall of the lens barrel, and the pressing portion presses the plurality of lenses toward the protruding portion side.

5. The lens unit according to claim 1,

the holder is provided in threaded engagement with a base end side of an inner peripheral wall of the lens barrel, and the pressing portion presses the plurality of lenses toward the protruding portion side.

6. The lens unit according to claim 1,

an annular projection projecting radially inward is formed on a base end side of an inner peripheral wall of the lens barrel,

7. The lens unit according to claim 1,

in a cross section along the optical axis direction, the concave portion has: a 1 st curved portion located radially inward and curved, a 2 nd curved portion located radially outward and curved, and a straight line portion located between the 1 st curved portion and the 2 nd curved portion.

8. The lens unit according to claim 1,

in a cross section along the optical axis direction, the concave portion is formed in a U shape.