Lens unit and camera module
A lens unit including a lens group formed by aligning a plurality of lenses along an optical axis; and a lens barrel having a cylindrical shape and including an inner accommodation space for accommodating and holding the lens group, the lens group including a first lens located to be closest to an object side and a second lens adjacent to the first lens on an image side, the lens unit including an annular body that integrates the first lens and the second lens and that is fit to outer circumferences of the first lens and the second lens to cover a joint portion between the first lens and the second lens from an outside, and the annular body is fit to an inner circumferential surface of the lens barrel, and includes a seal portion for tightly sealing an inside of an inter-lens space.
1. A lens unit comprising: a lens group formed by aligning a plurality of lenses along an optical axis; and a lens barrel having a cylindrical shape and including an inner accommodation space for accommodating and holding the lens group, the lens group including a first lens located to be closest to an object side and a second lens adjacent to the first lens on an image side, the lens unit comprising
an annular body that integrates the first lens and the second lens and that is fit to outer circumferences of the first lens and the second lens to cover a joint portion between the first lens and the second lens from an outside, wherein
the annular body is fit to an inner circumferential surface of the lens barrel, and includes
a first extension portion that extends in a direction of the optical axis along outer circumferential side surfaces of the first and second lenses,
a second extension portion between the second lens and a third lens adjacent to the second lens on the image side, wherein the second extension portion extends inward in a radial direction from an image-side end portion of the first extension portion,
a first seal for between the first lens and the first extension portion of the annular body, and
a second seal between the second lens and the second extension portion of the annular body.
2. The lens unit according to claim 1 , wherein the second extension portion includes a blocking wall portion having an annular shape for blocking warm air containing water vapor that flows from the image side to the object side in the inner accommodation space.
3. The lens unit according to claim 2 , wherein the blocking wall portion also serves as a spacer to be interposed between the second lens and the third lens, and to separate these lenses from each other in an optical axis direction.
4. The lens unit according to claim 3 , wherein the second seal is between the blocking wall portion and the second lens.
5. The lens unit according to claim 1 , wherein an adhesive for keeping airtightness is interposed between an outer surface of the annular body and an inner surface of the lens barrel.
6. A camera module comprising the lens unit according to claim 1 .
7. The lens unit according to claim 1 , wherein at least one of the first and second seals is an adhesive.
8. The lens unit according to claim 7 , wherein at least another one of the first and second seals is a gasket.
9. The lens unit according to claim 1 , wherein at least one of the first and second seals is a gasket.
10. The lens unit according to claim 1 , wherein the first extension portion includes a ledge facing the first lens on which the first seal is provided.
11. The lens unit according to claim 1 , wherein the second extension portion includes a step facing an object side of the second lens in which the second seal is provided.
12. The lens unit according to claim 1 , wherein the annular body is metal.
13. The lens unit according to claim 1 , further comprising a third seal between an inner surface of the second extension portion and the second lens.
14. The lens unit according to claim 13 , wherein the second extension portion includes a recess where the second extension portion extends from the first extension portion in which the third seal is provided.
15. The lens unit according to claim 1 , further comprising a cap secured to an object-side end portion of the lens barrel and extending in the direction of the optical axis along the lens barrel.
16. The lens unit according to claim 15 , further comprising a drain passage between the cap and the lens barrel.
17. The lens unit according to claim 15 , wherein the lens barrel includes a flange that extends radially outward from an outer surface of the lens barrel further than the cap.
18. The lens unit according to claim 1 , wherein the second lens directly abuts the first lens.
19. The lens unit according to claim 18 , wherein the joint portion faces the first extension.
20. The lens unit according to claim 19 , wherein the joint portion is below the first seal.