Lens unit

Abstract

To provide a lens unit capable of suppressing occurrence of misting of a first lens even if air between the first lens and a second lens held by a lens barrel contains moisture.SOLUTION: A lens unit 1 includes: a first lens 2; a lens group 4; and a lens barrel 3. The lens barrel 3 includes: a first cylindrical part 21 having a holding part 24 for holding the first lens 2; a second cylindrical part 22 for housing the lens group 4 in the inner peripheral side of the first cylindrical part 21; and a connection part 23 for connecting the first cylindrical part 21 and the second cylindrical part 22 in a diametric direction. A support surface 35a provided in the connection part 23 supports the first lens 2 in a position separated from the second cylindrical part 22 and the lens group 4. The lens barrel 3 has an annular groove 36 in the outer peripheral side of the support surface 35a, and includes a through hole 40 for connecting a space S between the lens group 4 and the first lens 2 to the outside of the lens barrel 3 in the inner peripheral side of the annular groove 36 and an image side X1 of the support surface 35a. An elastic member 37 seals an area between the first lens 2 and the connection part 23.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a lens unit capable of suppressing clouding of a lens within a lens barrel.

[0002] A lens unit used in an imaging device mounted on an automobile or a surveillance camera is described in Patent Document 1. The lens unit of this document includes a first lens, a lens group located on the image side of the first lens, and a lens barrel that holds the first lens and the lens group. The space between the first lens and the lens barrel is sealed by a first sealing member. The space between the second lens, which is the lens located on the most image side among the lenses of the lens group, and the lens barrel is sealed by a second sealing member.

[0003] Moreover, the lens unit of this document includes a communication passage in the lens barrel that connects the space between the first lens and the second lens inside the lens barrel and the outside of the lens barrel. The communication passage is for preventing the air in the space between the first lens and the second lens from being unable to be exhausted and making assembly difficult when the first lens is held in the lens barrel. Therefore, when the assembly of the lens unit is completed, the communication passage is blocked by a third sealing member.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the lens unit described above, the space between the first lens and the second lens is isolated from the outside by the first sealing member, the second sealing member, and the third sealing member. Therefore, water cannot enter this space from outside the lens barrel. However, if humid air is present in the space between the first lens and the second lens when the lens unit is assembled, condensation may occur on the object-facing surface of the first lens due to the moisture.

[0006] In view of the above problems, the objective is to provide a lens unit that can prevent or suppress fogging of the first lens even when the air between the first lens and the second lens contains moisture when the first lens and the second lens are held in the lens barrel. [Means for solving the problem]

[0007] To solve the above problems, the lens unit of the present invention comprises a first lens, a lens group located on the image side of the first lens, a lens barrel having a first cylindrical portion having a holding portion that holds the first lens from the outer circumference, a second cylindrical portion located on the image side of the first lens and holding the lens group from the outer circumference on the inner circumference side of the first cylindrical portion, and an annular connecting portion that connects the first cylindrical portion and the second cylindrical portion radially on the image side of the holding portion, and an annular elastic member, wherein the connecting portion has a first lens support having a support surface that supports the outer edge portion of the first lens from the image side. The lens barrel comprises a portion, the support surface supporting the first lens at a position spaced apart from the second barrel and the lens group toward the object, the lens barrel having an annular groove recessed toward the image side on the outer circumference of the support surface, and a through hole located on the inner circumference of the annular groove and toward the image side of the support surface that connects the space between the second lens, which is located furthest toward the object in the lens group, and the first lens, and the space on the image side of the connecting portion and outside the second barrel, and the elastic member is arranged in the annular groove to seal the space between the first lens and the connecting portion.

[0008] According to the present invention, the lens barrel has a space between the first lens and the second lens held in the lens barrel and A through-hole is provided that connects the second barrel section to the space outside the second barrel section on the image side of the barrel connection. Therefore, even if the air in this space contains moisture, the moisture-containing air can escape through the through-hole to the space outside the second barrel section on the image side of the barrel connection. Thus, fogging on the image-side surface of the first lens can be prevented or suppressed.

[0009] In the present invention, the lens barrel can be made of amorphous resin. Amorphous resin has superior water absorption properties compared to crystalline resin. Therefore, if the air in the space contains moisture, this moisture can be absorbed by the lens barrel. Thus, it is easier to suppress the occurrence of fogging on the first lens.

[0010] In the present invention, the first cylindrical portion is provided with an annular skirt portion on the image side of the connecting portion, facing the second cylindrical portion with a gap between them in the radial direction, the through hole is provided in the connecting portion, and the through hole can connect the space and the gap between the skirt portion and the second cylindrical portion.

[0011] In this case, the second cylindrical portion includes an annular portion having a tapered outer surface at the end on the object side that inclins inward toward the object side, and a bent portion that bends inward from the end of the annular portion on the object side and contacts the outer edge of the second lens from the object side. One end opening of the through hole is provided on the image-facing surface of the connection portion at a position that overlaps with the support surface when viewed from the optical axis direction, and the other end opening of the through hole is provided on the first lens support portion and faces the tapered outer surface of the annular portion from the radially outer side. In this way, the radial size of the connection portion can be suppressed compared to the case where the through hole is provided on the inside of the first lens support portion in the connection portion.

[0012] In the present invention, the through-holes can be a first through-hole and a second through-hole located at positions 180° apart around the optical axis. In this way, when the lens unit is used with the optical axis horizontal, the first through-hole can be positioned on the upper side of the space and the second through-hole can be positioned on the lower side of the space. Therefore, humid air can be released to the outside through the first through-hole by utilizing convection caused by the temperature of the outside air.

[0013] In the present invention, the second cylindrical portion has a bent portion that bends inward from the end on the object side and abuts against the outer edge of the second lens from the object side, and a support portion that protrudes inward and supports the lens group from the image side, the bent portion has a notch in a part of the circumferential direction, the support portion has the through hole at a position that overlaps with the notch when viewed from the optical axis direction, and a communication groove extending in the optical axis direction is provided on the inner surface portion of the second cylindrical portion between the bent portion and the support portion, connecting the notch and the through hole. In this way, if the air in the space between the first lens and the second lens held in the lens barrel contains moisture, this air can be discharged to the image side of the second cylindrical portion.

[0014] In the present invention, the second cylindrical portion has a bent portion that bends inward from the end on the object side and abuts against the outer edge of the second lens from the object side, and a support portion that protrudes inward and supports the lens group from the image side, and the second cylindrical portion has a plurality of ribs extending in the optical axis direction on the inner surface portion of the second cylindrical portion between the bent portion and the support portion, the plurality of ribs are arranged in the circumferential direction and abut against the lens group from the outer side to position the lens group radially, the bent portion has a notch at a position that overlaps with the gap between adjacent ribs in the circumferential direction when viewed from the optical axis direction, and the support portion has a through hole at a position that overlaps with the notch when viewed from the optical axis direction, and the gap can be a communication groove that connects the notch and the through hole in the optical axis direction. In this way, by utilizing multiple ribs that radially position the lens group inside the second barrel, the space between the first and second lenses held in the lens barrel and the through hole are defined. They can be connected. Therefore, if the air in the space between the first lens and the second lens held in the lens barrel contains moisture, this air can be discharged to the image side of the second barrel.

[0015] In the present invention, the notches may include a first notch and a second notch located 180° apart around the optical axis, the through-holes may include a first through-hole that overlaps with the first notch when viewed from the optical axis direction, and a second through-hole that overlaps with the second notch, and the communication grooves may include a first communication groove extending in the optical axis direction and connecting the first notch and the first through-hole, and a second communication groove extending in the optical axis direction and connecting the second notch and the second through-hole. In this way, when the lens unit is used with the optical axis horizontal, the first notch, the first communication groove, and the first through-hole can be positioned on the upper side of the space, and the second notch, the second communication groove, and the second through-hole can be positioned on the lower side of the space. Therefore, humid air can be released to the outside through the first through-hole by utilizing convection caused by the temperature of the outside air. [Effects of the Invention]

[0016] According to the present invention, the lens barrel is provided with a through hole that communicates the space between the first lens and the second lens held in the lens barrel and the space outside the second barrel portion on the image side of the connection portion of the lens barrel. Therefore, even when the air in the space contains moisture, the moist air can be discharged to the outside of the lens barrel through the through hole. Thus, it is possible to prevent or suppress the occurrence of fogging on the image-side surface of the first lens or the like.

Brief Description of the Drawings

[0017] [Figure 1] It is an external perspective view of a lens unit to which the present invention is applied. [Figure 2] It is a cross-sectional view taken along line A-A in FIG. 1. [Figure 3] It is a cross-sectional view taken along line B-B in FIG. 1. [Figure 4] It is an exploded perspective view of the lens unit. [Figure 5] It is a perspective view of the lens barrel when viewed from the image side. [Figure 6] It is a perspective view of the lens unit of Example 2. [Figure 7] It is a cross-sectional view taken along line D-D in FIG. 6. [Figure 8] It is an exploded perspective view of the lens unit of Example 2. [Figure 9] It is a plan view of the lens barrel of the lens unit of Example 2 when viewed from the object side. [Figure 10] It is a perspective view of the lens barrel of the lens unit of Example 2 when viewed from the image side.

Modes for Carrying Out the Invention

[0018] Hereinafter, embodiments of a lens unit to which the present invention is applied will be described with reference to the drawings.

[0019] (Example 1) Figure 1 is an external perspective view of a lens unit to which the present invention is applied. Figure 2 is a cross-sectional view taken along line AA of Figure 1. Figure 3 is a cross-sectional view taken along line BB of Figure 1. Figure 4 is an exploded perspective view of the lens unit. Figure 5 is a perspective view of the lens barrel as seen from the image side. The lens unit 1 in this example is used in imaging devices mounted on automobiles and surveillance cameras.

[0020] (optical system) As shown in Figure 1, the lens unit 1 comprises a first lens 2 and a lens barrel 3. Furthermore, as shown in Figures 2 to 4, the lens unit 1 has a lens group 4 held by the lens barrel 3 at the image side X1 of the first lens 2, along the optical axis L of the first lens 2 in the optical axis direction X. The lens group 4 comprises a second lens 5, a third lens 6, a fourth lens 7, and a fifth lens 8, arranged in the optical axis direction X from the object side to the image side X1. The fifth lens 8 is a cemented lens formed by joining two lenses. Each lens constituting the lens group 4 has a smaller outer diameter than the first lens 2. Furthermore, the lens unit 1 includes an annular light-shielding sheet 9 positioned between the second lens 5 and the third lens 6, and an annular aperture 10 positioned between the third lens 6 and the fourth lens 7.

[0021] The first lens 2 is made of resin or glass. The first lens 2 is a meniscus lens. As shown in Figure 2, the first lens 2 has a curved surface on the object side X2 that protrudes toward the object side X2. The first lens 2 also has a curved surface 2a on the image side X1 that is recessed toward the object side X2, and an annular flange surface 2b (outer edge portion) that extends in a direction perpendicular to the optical axis L on the outer circumference of the curved surface. The flange surface 2b is coated with black ink for light shielding.

[0022] The second lens 5 is made of resin. The second lens 5 is a meniscus lens. The second lens 5 has a curved surface on the object side X2 that protrudes toward the object side X2, and a curved surface on the image side X1 that is recessed toward the object side X2. The third lens 6 is made of resin. The third lens 6 has a curved surface on the object side X2 that faces toward the object side X2, and a curved surface on the image side X1 that protrudes toward the image side X1. The fourth lens 7 is made of glass. The fourth lens 7 has a smaller outer diameter than the second lens 5, the third lens 6, and the fifth lens 8. The fourth lens 7 is held in an annular holder 11 and is positioned between the third lens 6 and the fifth lens 8.

[0023] The fifth lens 8 comprises an object-side lens 13 and an image-side lens 14 located on the image side X1 of the object-side lens 13. Both the object-side lens 13 and the image-side lens 14 are made of resin. The object-side lens 13 has a curved surface on the object side X2 that curves toward the image side X1, and a curved surface on the image side X1 that is recessed toward the object side X2. The image-side lens 14 has a curved surface on the object side X2 that protrudes toward the object side X2, and a curved surface on the image side X1 that protrudes toward the image side X1. The image-side lens 14 is joined to the object-side lens 13 with the curved surface protruding toward the object side X2 inserted into the curved surface of the object-side lens 13 that is recessed toward the object side X2. The outer diameter of the object-side lens 13 is smaller than the outer diameter of the image-side lens 14. Therefore, the object-side lens 13 has an annular flange portion 13a located on the outer circumference of the image-side lens 14 when viewed from the optical axis direction X.

[0024] Here, as shown in Figure 4, the second lens 5, the third lens 6, the fourth lens 7, the fifth lens 8, and the holder 11 are each provided with a notch 16 in a portion of the circumferential direction that extends linearly in the circumferential direction when viewed from the optical axis direction X. The holder 11 that holds the second lens 5, the third lens 6, and the fourth lens 7, and the fifth lens 8 are stacked with the notches 16 positioned at the same angular position around the optical axis L.

[0025] (Telescope tube) The lens barrel 3 is made of resin. In this example, the lens barrel 3 is made of amorphous resin. The lens barrel 3 is made of polycarbonate.

[0026] As shown in Figure 2, the lens barrel 3 includes a first cylindrical portion 21, a second cylindrical portion 22 located on the inner circumference side of the first cylindrical portion 21, and a connecting portion 23 that protrudes radially inward from the middle of the optical axis direction X of the first cylindrical portion 21 and connects the first cylindrical portion 21 and the second cylindrical portion 22 in the radial direction. The first cylindrical portion 21 has a holding portion 24 on the object side X2 of the connecting portion 23 that holds the first lens 2 from the outer circumference. The first cylindrical portion 21 also has a skirt portion 25 on the image side X1 of the connecting portion 23 that surrounds the second cylindrical portion 22 from the outer circumference. Furthermore, the first cylindrical portion 21 has a first bent portion 26 at the end on the object side X2 that bends inward and contacts the outer edge of the first lens 2 from the object side X2. The first bent portion 26 is provided by crimping the end on the object side X2 of the first cylindrical portion 21.

[0027] The second cylindrical portion 22 houses the lens group 4 on its inner circumference. The second cylindrical portion 22 has an annular portion 28 at the end on the object side X2, which has a tapered outer surface 28a that slopes inward toward the inner circumference toward the object side X2, and a portion that bends inward toward the outer circumference from the end on the object side X2 of the annular portion 28 to the outer circumference of the second lens 5. The second cylindrical portion 22 includes a second bent portion 29 that contacts X2. The second cylindrical portion 22 also includes an annular support portion 30 that protrudes radially inward from the image side X1 portion to support the lens group 4.

[0028] The support portion 30 contacts the flange portion 13a of the object-side lens 13 of the fifth lens 8 from the image-side X1, supporting the lens group 4 from the image-side X1. The support portion 30 also includes an annular plate portion 31 that protrudes radially inward from the end portion of the object-side X2. The inner edge of the annular plate portion 31 defines the circular opening 32. Here, neither the support portion 30 nor the annular plate portion 31 is in contact with the image-side lens 14 of the fifth lens 8. That is, the support portion 30 faces the image-side lens 14 with a gap in the radial direction. The annular plate portion 31 corresponds to the image-side lens 14 with a gap in the optical axis direction X. An image sensor (not shown) is fixed to the annular plate portion 31 from the image-side X1. The image sensor seals the circular opening 32. Here, the second bent portion 29 is provided by crimping the end of the object-side X2 of the second cylindrical portion 22. The second bent portion 29 and the support portion 30 hold the lens group 4 from both sides in the optical axis direction X.

[0029] Furthermore, as shown in Figure 4, the second cylindrical portion 22 is provided with a plurality of ribs 33 extending in the optical axis direction X between the second bent portion 29 and the support portion 30 on the inner circumferential surface. The plurality of ribs 33 are arranged in the circumferential direction. When the lens group 4 is housed in the second cylindrical portion 22, each rib 33 abuts from the radially outer side against the holder 11 that holds the second lens 5, the third lens 6, the fourth lens 7, and the object-side lens 13 of the fifth lens 8, thereby positioning the lens group 4 radially.

[0030] Here, a gap extending in the optical axis direction X is formed between the holder 11 that holds the second lens 5, the third lens 6, and the fourth lens 7, and the fifth lens 8, and the second cylindrical portion 22, due to the notches 16 provided in them. Also, a gap extending in the optical axis direction X is formed between the holder 11 that holds the second lens 5, the third lens 6, and the fourth lens 7, and the fifth lens 8, and the second cylindrical portion 22, between adjacent ribs 33 in the circumferential direction.

[0031] As shown in Figure 2, the connecting portion 23 includes a first lens support portion 35 having a support surface 35a that supports the flange surface 2b of the first lens 2 from the image side X1. The support surface 35a supports the first lens 2 at a position spaced apart from the second cylindrical portion 22 and the lens group 4 toward the object side X2. The first bent portion 26 and the support surface 35a hold the first lens 2 from both sides in the optical axis direction X.

[0032] Here, the lens barrel 3 is provided with an annular groove 36 recessed on the outer circumference of the support surface 35a toward the image side X1. An annular elastic member 37 is inserted into the annular groove 36. The elastic member 37 elastically deforms in the optical axis direction X to seal the space between the first lens 2 and the connecting portion 23. The lens barrel 3 is also provided with a through hole 38 located on the inner circumference of the annular groove 36 and toward the image side X1 of the support surface 35a, which connects the space S between the second lens 5 and the first lens 2 with the space outside the second cylindrical portion 22, which is toward the image side X1 of the connecting portion 23.

[0033] The through-hole 38 is provided so as to penetrate the connecting portion 23 in the optical axis direction X. Furthermore, as shown in Figures 3 and 5, in this example, the through-hole 38 includes a first through-hole 38(1) and a second through-hole 38(2) provided at positions 180° apart around the optical axis L. As can be seen from Figure 3, the end opening 38a on the image side X1 of each through-hole 38 is provided at a position that coincides with the support surface 35a when viewed from the optical axis direction X on the surface of the connecting portion 23 facing the image side X1. As shown in Figure 5, the end opening 38b on the object side X2 of each through-hole 38 is provided on the inner circumferential surface of the first lens support portion 35 and faces the tapered outer circumferential surface 28a of the annular portion 28 of the second cylindrical portion 22 from the radially outer side. Each through-hole 38 widens circumferentially toward the end at the end opening 38a on the image side X1.

[0034] (Effects and Benefits) In this example, the lens barrel 3 has a first lens 2 and a second lens 5 held in the lens barrel 3. A through-hole 38 is provided that connects the space with the space outside the second barrel section 22 at the image side X1 from the connection part 23 of the lens barrel 3. This through-hole 38 is not sealed with a sealant or the like. Therefore, even if the air in the space contains moisture, the moisture-containing air can escape through the through-hole 38 to the space outside the second barrel section 22 at the image side X1 from the connection part 23 of the lens barrel 3. Thus, it is possible to prevent or suppress the occurrence of fogging on the image side X1 surface of the first lens 2.

[0035] In this example, the through-hole 38 includes a first through-hole 38(1) and a second through-hole 38(2) positioned 180° apart around the optical axis L. Therefore, when the lens unit 1 is used with the optical axis L horizontal, the first through-hole 38(1) can be positioned above the space S, and the second through-hole 38(2) can be positioned below the space S. Thus, by utilizing the convection caused by the temperature of the outside air, humid air can be released to the outside through the first through-hole 38(1).

[0036] Furthermore, the end portion of the second cylindrical portion 22 on the object side X2 includes an annular portion 28 having a tapered outer surface 28a that inclins inward toward the inner circumference toward the object side X2, and a second bent portion 29 that bends inward toward the inner circumference from the end of the annular portion 28 on the object side X2 and contacts the outer edge of the second lens 5 from the object side X2. The end opening 38a on the image side X1 of the through hole 38 is provided on the surface of the connecting portion 23 facing the image side X1, at a position that overlaps with the support surface 35a when viewed from the optical axis direction X, and the end opening 38b on the object side X2 of the through hole 38 is provided on the surface of the first lens support portion 35 that faces radially inward and faces the tapered outer surface 28a of the annular portion 28 from the radially outward side. Therefore, compared to the case where the through hole 38 is provided on the inner circumference side of the first lens support portion 35, the radial size of the connecting portion 23 can be suppressed.

[0037] In this example, the lens barrel 3 is made of amorphous resin. Amorphous resin has superior water absorption properties compared to crystalline resin. Therefore, if the air in the space S contains moisture, this moisture can be absorbed by the lens barrel 3. Thus, it is easier to suppress the occurrence of fogging on the first lens 2.

[0038] (Example 2) Figure 6 is a perspective view of the lens unit of Example 2. Figure 7 is a cross-sectional view of Figure 6 along line DD. Figure 8 is an exploded perspective view of the lens unit of Example 2. Figure 9 is a plan view of the lens barrel of the lens unit of Example 2 as seen from the object side X2. Figure 10 is a perspective view of the lens barrel of the lens unit of Example 2 as seen from the image side X1. As shown in Figure 6, the lens unit 1A of this example has the same external shape as the lens unit 1. Also, the cross-sectional view along line CC in Figure 6 is the same as the cross-sectional view along line AA of the lens unit 1 shown in Figure 2. Here, the lens unit 1A of this example differs in the configuration of the lens barrel 3A from the lens barrel 3 of the lens unit 1b, but the optical system configuration is the same as that of the lens unit 1. Therefore, only the lens barrel 3 is described, and other descriptions are omitted. Also, the lens barrel 3A of the lens unit 1A has a configuration corresponding to the lens barrel 3 of the lens unit 1. Therefore, corresponding components are given the same reference numerals, and their descriptions are omitted.

[0039] (Telescope tube) The lens barrel 3A is made of amorphous resin. As shown in Figures 2 and 7, the lens barrel 3A has a first cylindrical portion 21, a second cylindrical portion 22 located on the inner circumference side of the first cylindrical portion 21, and a connecting portion 23 that protrudes radially inward from the middle of the optical axis direction X of the first cylindrical portion 21 and connects the first cylindrical portion 21 and the second cylindrical portion 22 in the radial direction. The first cylindrical portion 21 has a holding portion 24 on the object side X2 of the connecting portion 23. The first cylindrical portion 21 also has a skirt portion 25 on the image side X1 of the connecting portion 23. Furthermore, the first cylindrical portion 21 has a first bent portion 26 at the end on the object side X2 that bends inward and contacts the outer edge of the first lens 2 from the object side X2.

[0040] The second cylindrical portion 22 houses the lens group 4 inside. The second cylindrical portion 22 includes an annular portion 28 at the object-side end X2, which has a tapered outer peripheral surface 28a that inclins inward toward the inner circumference toward the object-side X2, and a second bent portion 29 that bends inward toward the inner circumference from the end of the annular portion 28 toward the object-side X2 and contacts the outer peripheral edge of the second lens 5 toward the object-side X2. The second cylindrical portion 22 also includes an annular support portion 30 that protrudes radially inward from the image-side portion X1 to support the lens group 4. The support portion 30 includes an annular plate portion 31 that protrudes radially inward from the end portion of the object-side X2. The inner edge of the annular plate portion 31 defines the circular opening 32.

[0041] Here, as shown in Figures 8 and 9, the second bent portion 29 of the second cylindrical portion 22 is provided with a radially shaped notch 41 in a portion of its circumferential direction. In this example, the notch 41 comprises a first notch 41(1) and a second notch 41(2) located at two locations 180° apart around the optical axis L. Also, as shown in Figures 8, 9, and 10, the support portion 30 is provided with a circular through-hole 40 at a position that overlaps with the notch 41 when viewed from the optical axis direction X. In this example, the through-hole 40 comprises a first through-hole 40(1) that overlaps with the first notch 41(1) when viewed from the optical axis direction X, and a second through-hole 40(2) that overlaps with the second notch 41(2). Furthermore, as shown in Figure 8, a communication groove 42 is provided on the inner circumferential surface portion 34 of the second cylindrical portion 22 between the second bent portion 29 and the support portion 30, extending in the optical axis direction X and connecting the notch 41 and the through hole 40. The cross-section of the communication groove 42 is arc-shaped. In this example, the communication groove 42 includes a first communication groove 42(1) extending in the optical axis direction X and connecting the first notch 41(1) and the first through hole 40(1), and a second communication groove 42(2) extending in the optical axis direction X and connecting the second notch 41(2) and the second through hole 40(2).

[0042] Furthermore, the second cylindrical portion 22 is provided with a plurality of ribs 33 extending in the optical axis direction X between the second bent portion 29 and the support portion 30 on the inner circumferential surface 34. The plurality of ribs 33 are arranged in the circumferential direction. When the lens group 4 is housed in the second cylindrical portion 22, each rib 33 abuts from the radially outer side against the holder 11 that holds the second lens 5, the third lens 6, the fourth lens 7, and the object-side lens 13 of the fifth lens 8, thereby positioning the lens group 4 radially. A gap extending in the optical axis direction X is formed between the holder 11 that holds the second lens 5, the third lens 6, the fourth lens 7, and the fifth lens 8 and the second cylindrical portion 22 by the notches 16 provided in them. In addition, a gap extending in the optical axis direction X is formed between the holder 11 that holds the second lens 5, the third lens 6, the fourth lens 7, and the fifth lens 8 and the second cylindrical portion 22 between adjacent ribs 33 in the circumferential direction.

[0043] In this example, the notch 41 is provided in a position that overlaps with the rib 33 when viewed from the optical axis direction X. Therefore, the first communication groove 42(1) and the second communication groove 42(2) are provided in two ribs 33 located opposite each other across the optical axis L, dividing each rib 33 into two in the circumferential direction. The radial depth dimension of the first communication groove 42(1) and the second communication groove 42(2) is greater than the radial height dimension of each rib 33. Here, the notch 41, the communication groove 42, and the through hole 40 may be located between the ribs 33 in the circumferential direction. That is, the communication groove 42 may be formed on the inner circumferential surface 34 between the ribs 33 in the second cylindrical portion 22.

[0044] The connecting portion 23 includes a first lens support portion 35 having a support surface 35a. The support surface 35a supports the first lens 2 at a position spaced apart from the second cylindrical portion 22 and the lens group 4 toward the object side X2. The first bent portion 26 and the support surface 35a hold the first lens 2 from both sides in the optical axis direction X.

[0045] Furthermore, the lens barrel 3A is provided with an annular groove 36 recessed on the outer circumference of the support surface 35a toward the image side X1. An annular elastic member 37 is inserted into the annular groove 36. The elastic member 37 elastically deforms in the optical axis direction X to seal the space between the first lens 2 and the connecting portion 23. In addition, the lens barrel 3A is provided with an annular groove 36 The lens also has a through hole 40 on the inner circumference side and on the image side X1 of the support surface 35a, which connects the space S between the second lens 5 and the first lens 2 with the space outside the second cylindrical portion 22 on the image side X1 of the connecting portion 23.

[0046] (Effects and Benefits) In this example, the space S between the first lens 2 and the second lens 5 held in the lens barrel 3A communicates with the outside of the lens unit 1 through a notch 41 provided in the second bent portion 29 of the second barrel portion 22, a communication groove 42 provided in the inner circumferential surface 34 of the second barrel portion 22, and a through hole 40. Therefore, even if the air in space S contains moisture, the moisture-containing air can be released through the through hole 40 into the space outside the second barrel portion 22 on the image side X1 of the connection portion 23 of the lens barrel 3A. Thus, fogging on the image side X1 surface of the first lens 2 can be prevented or suppressed.

[0047] Furthermore, in this example, the lens unit 1 is provided with a first notch 41(1), a first communication groove 42(1), and a first through hole 40(1) located at positions 180° apart around the optical axis L, and a second notch 41(2), a second communication groove 42(2), and a second through hole 40(2). Therefore, when the lens unit 1 is used with the optical axis L horizontal, the first notch 41(1), the first communication groove 42(1), and the first through hole 40(1) can be positioned on the upper side of the space S, and the second notch 41(2), the second communication groove 42(2), and the second through hole 40(2) can be positioned on the lower side of the space S. Thus, by utilizing the convection generated due to the temperature of the outside air, humid air can be released to the outside through the first through hole 40(1).

[0048] Furthermore, the lens barrel 3A is made of amorphous resin. Amorphous resin has superior water absorption properties compared to crystalline resin. Therefore, if the air in space S contains moisture, this moisture can be absorbed by the lens barrel 3A. Thus, the occurrence of fogging on the first lens 2 can be further suppressed.

[0049] Furthermore, if the notch 41 provided in the second bent portion 29 of the second cylindrical portion 22 is positioned to overlap with the gap between the ribs 33 when viewed from the optical axis direction X, the gap between the ribs 33 may be used as a communication groove. In this case, if the through hole 40 is positioned to overlap with the notch 41 when viewed from the optical axis direction X, the gap between the ribs 33 in the circumferential direction becomes a communication groove that connects the notch 41 and the through hole 40 in the optical axis direction X. Therefore, the air in the space S can be released to the outside through the notch 41, the gap between the ribs 33, and the through hole 40. [Explanation of symbols]

[0050] 1·1A…Lens unit, 2…First lens, 2a…Curved surface, 2b…Flange surface, 3·3A…Lens barrel, 4…Lens group, 5…Second lens, 6…Third lens, 7…Fourth lens, 8…Fifth lens, 9…Light-shielding sheet, 10…Aperture, 11…Holder, 13…Object-side lens, 13a…Flange portion, 14…Image-side lens, 16…Notch portion, 21…First barrel portion, 22…Second barrel portion, 23…Connecting portion, 24…Retaining portion 25...Skirt portion, 26...First bent portion, 28...Annular portion, 28a...Tapered outer surface, 29...Second bent portion, 30...Support portion, 31...Annular plate portion, 32...Circular opening, 33...Rib, 34...Inner surface, 35...First lens support portion, 35a...Support surface, 36...Annular groove, 37...Elastic member, 38...Through hole, 38a...End opening, 38b...End opening, 40...Through hole, 41...Notch, 42...Communication groove, L...Optical axis

Claims

1. The first lens, A group of lenses located on the image side of the first lens, A lens barrel comprising: a first barrel having a holding portion for holding the first lens from the outer circumference; a second barrel located on the image side of the first lens and holding the lens group from the outer circumference on the inner circumference side of the first barrel; and an annular connecting portion connecting the first barrel and the second barrel radially on the image side of the holding portion; It has an annular elastic member, The connecting portion includes a first lens support portion having a support surface that supports the outer peripheral edge portion of the first lens from the image side, The support surface supports the first lens at a position spaced apart from the second barrel and the lens group toward the object. The lens barrel is provided with an annular groove on the outer circumference of the support surface that is recessed toward the image side, and a through hole located on the inner circumference of the annular groove and toward the image side of the support surface that connects the space between the second lens located furthest toward the object side of the lens group and the first lens, and the space on the image side of the connecting portion and outside the second barrel portion. The elastic member is positioned in the annular groove to seal the space between the first lens and the connecting portion. The second cylindrical portion has a bent portion that bends inward from the end on the object side and contacts the outer edge of the second lens from the object side, and a support portion that protrudes inward and supports the lens group from the image side. The aforementioned bent portion is provided with a notch in a part of the circumferential direction, The support portion is provided with the through hole at a position that overlaps with the notch when viewed from the optical axis direction. A lens unit characterized in that a communication groove is provided on the inner circumferential surface portion of the second cylindrical portion between the bent portion and the support portion, extending in the direction of the optical axis and connecting the notch and the through hole.

2. The lens unit according to claim 1, characterized in that the lens barrel is made of amorphous resin.

3. The second cylindrical portion has a bent portion that bends inward from the end on the object side and contacts the outer edge of the second lens from the object side, and a support portion that protrudes inward and supports the lens group from the image side. The second cylindrical portion is provided with a plurality of ribs extending in the optical axis direction on the inner circumferential surface portion between the bent portion and the support portion on the inner circumferential surface portion of the second cylindrical portion, Multiple ribs are arranged in the circumferential direction and contact the lens group from the outer periphery to position the lens group radially. The bent portion is provided with a notch at a position that overlaps with the gap between adjacent ribs in the circumferential direction when viewed from the optical axis direction. The support portion is provided with the through hole at a position that overlaps with the notch when viewed from the optical axis direction. The lens unit according to claim 1 or 2, characterized in that the gap is a communication groove that connects the notch and the through hole in the optical axis direction.

4. The aforementioned notches include a first notch and a second notch, which are positioned 180° apart around the optical axis. The through-holes include a first through-hole that overlaps with the first notch when viewed from the optical axis direction, and a second through-hole that overlaps with the second notch. The lens unit according to any one of claims 1 to 3, characterized in that the communication groove comprises a first communication groove extending in the optical axis direction and connecting the first notch and the first through hole, and a second communication groove extending in the optical axis direction and connecting the second notch and the second through hole.

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