JP2011081047A - Drip-proof structure of lens barrel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a drip-proof structure, which is between two cylindrical members relatively rotating without relatively moving in an axis line direction, has small rotation resistance and is excellent in seal performance. <P>SOLUTION: The drip-proof structure of a lens barrel includes: an annular sealing surface, which is formed on one of the two cylindrical members, and whose extended surface crosses the axis line; and a seal ring composed of an elastic material fixed to the other of the two cylindrical members. The seal ring has an annular elastic lip which elastically contacts the annular sealing surface from the axis line direction (thrust direction). The seal ring further forms an outside communication annular groove, whose outside in a radial direction communicates with the outside of the cylindrical member, in the position of the inside in a radial direction from the elastic contact position with the annular sealing surface in the annular elastic lip. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a drip-proof structure between two cylindrical members that rotate relative to each other in a lens barrel.

  In the lens barrel, there are many two cylindrical members that rotate relative to each other. When the two cylindrical members that rotate relative to each other are made drip-proof, the seal ring is interposed between the cylindrical surfaces of the two cylindrical members in the type in which the two cylindrical members are relatively moved in the axial direction (Patent Document 1, 2). In the type in which the two cylindrical members do not move relative to each other in the axial direction, it is common to place an O-ring on the relative rotation surfaces of the two cylindrical members.

Japanese Patent Laid-Open No. 11-119075 JP 2002-14268 A

  However, if the O-ring increases the drip-proof (waterproof) performance, the sliding resistance increases, and if it is a member that manually rotates, the feeling of operation is greatly impaired. There is a problem that becomes too large.

  The present invention is a drip-proof structure between two cylindrical members that rotate relative to each other without relative movement, particularly in the axial direction, and has a small rotational resistance and excellent drip-proof (sealing performance). The purpose is to obtain a structure.

  The present invention provides an external communication annular groove that actively and temporarily stores water droplets that have entered the vicinity of the seal surface in a drip-proof structure in which a seal ring made of an elastic member is sealed by elastic contact with the seal surface. This is based on the viewpoint that if sealing is performed radially outward from the external communication annular groove, sufficient sealing can be achieved while suppressing rotational resistance.

  The present invention is a drip-proof structure between two cylindrical members that rotate relative to each other without relatively moving in the axial direction, and an extension surface formed on one of the two cylindrical members is an axis. An annular sealing surface that intersects and a sealing ring made of an elastic material fixed to the other cylindrical member, and the sealing ring has an annular elastic lip that elastically contacts the annular sealing surface from the axial direction. An external communication annular groove is formed in the radially inner position from the position of elastic contact with the annular seal surface of the annular elastic lip so that the radially outer side communicates with the outside of the cylindrical member.

  In one aspect, the other cylindrical member is provided with an outer cylindrical surface and a seal surface facing surface that is connected to one end portion of the outer cylindrical surface and faces the annular seal surface of the one cylindrical member, Is provided with a fixed cylindrical portion fixed in contact with the outer cylindrical surface and the seal surface facing surface, and an annular elastic lip extending radially outward from the fixed cylindrical portion. It can be constituted by a fixed cylindrical portion of the seal ring, an annular elastic lip, and a seal surface facing surface of the other cylindrical member.

  In another aspect, the other cylindrical member is provided with a seal surface facing surface opposite to the annular seal surface of the one cylindrical member, and the seal ring includes a fixed disk portion along the seal surface facing surface, and A U-shaped portion in which a radially inner end portion of the fixed disk portion is folded outward, and the annular elastic lip connected to the U-shaped portion are provided. The fixed disk part, the U-shaped part, and the annular elastic lip can be used.

  The seal ring can be provided with a fixed cylindrical portion that is continuous with the fixed disk portion and extends to the opposite side of the annular elastic lip and is fixed to the other cylindrical member.

  The one cylindrical member is preferably provided with an eaves cylindrical portion positioned radially outward of the external communication annular groove.

  In the other cylindrical member, in addition to the external communication annular groove, an annular primary introduction groove is preferably formed on the side farther from the annular elastic lip than the external communication annular groove.

  It is practical that both the annular seal surface and the seal surface facing surface are specifically surfaces orthogonal to the axis.

  Specifically, the seal ring is preferably made of silicone rubber.

  According to the present invention, it is a drip-proof structure between two cylindrical members that rotate relative to each other without moving relative to each other in the axial direction, and does not cause an increase in rotational resistance while having excellent drip-proof properties (sealability). A drip-proof structure can be obtained.

1 is an upper half sectional view of an entire lens barrel showing an embodiment of a drip-proof structure of a lens barrel according to the present invention. It is an expanded sectional view of the principal part of FIG. FIG. 6 is an upper half sectional view of the entire lens barrel showing another embodiment of the drip-proof structure of the lens barrel according to the present invention. It is an expanded sectional view of the principal part of FIG.

  1 and 2 show an embodiment of a drip-proof structure of a lens barrel according to the present invention. The overall structure of this lens barrel will be described with reference to FIG. 1. This lens barrel is roughly divided into a fixed barrel 10, a rotary barrel 20, and a rectilinear barrel 30 having an optical axis O as a rotational symmetry axis. Each of these barrels is composed of a plurality of members, but the fixed barrel 10 and the rotary barrel 20 are hatched in different directions as a whole, and the rectilinear barrel 30 is hatched. Absent. In the front-rear direction in this specification, the left direction in the figure is “front”, and the right direction in the figure is “rear”.

  An inner flange 21 is formed at the rear end of the rotary lens barrel 20, and the fixed lens barrel 10 is restricted from moving in the direction of the optical axis O across the inner flange 21, and only rotates. An enabling annular groove 11 is formed. A cam groove (or a lead groove) 12 is formed on the inner peripheral surface of the fixed barrel 10, and a cam follower 31 that protrudes radially on the peripheral surface of the rectilinear barrel 30 is fitted into the cam groove 12. ing. The cam follower 31 is simultaneously fitted in a rectilinear guide groove 22 formed in the rotary lens barrel 20 and parallel to the optical axis O. Therefore, when the rotary lens barrel 20 is rotated, the rectilinear lens barrel 30 (first lens unit L1) moves forward and backward in the optical axis O direction according to the relationship between the cam groove 12 and the rectilinear guide groove 22. The second lens group L2 is fixed to the fixed barrel 10. A mount ring 13 that is attached to and detached from a camera body (not shown) is fixed to the rear end portion of the fixed barrel 10.

  The drip-proof structure targeted by this embodiment is provided between the fixed lens barrel 10 and the rotating lens barrel 20. Now, two cylindrical members that rotate relative to each other without relative movement in the axial direction are fixed to a rotary operation cylinder (one cylindrical member) 25 that is a part of the rotary lens barrel 20 and rotates integrally with the rotary lens barrel 20. When a fixed cylinder member (the other cylindrical member) 15 that is a part of the lens barrel 10 and is integrally fixed to the fixed lens barrel 10, water droplets are formed on the distal end portion of the fixed cylinder member 15 and the distal end portion of the rotation operation cylinder 25. There is a gap S that can enter. The seal ring 40 (the drip-proof structure of this embodiment) prevents water droplets that have entered from the gap S from entering behind the seal ring 40.

  As shown in FIG. 2, the fixed cylinder member 15 includes a large-diameter outer cylindrical surface 16 centered on the optical axis O, a seal surface facing surface 17 orthogonal to the optical axis O, and the optical axis O in order from the front. A small-diameter outer cylindrical surface 18 is provided, and a step recess 19 is provided at the intersection of the large-diameter outer cylindrical surface 16 and the seal surface facing surface 17.

  On the other hand, the rotation operation cylinder 25 has a bowl cylindrical portion 26 centering on the optical axis O that forms the gap S facing the stepped recess 19, and is orthogonal to the optical axis O at the back of the bowl cylindrical portion 26. An annular sealing surface 27 is formed. The above-described large-diameter outer cylindrical surface 16 and the sealing surface facing surface 17 of the fixed cylindrical member 15 and the cylindrical portion 26 and the annular sealing surface 27 of the rotary operation cylinder 25 have a rectangular cross section and a donut-shaped space centered on the optical axis O. Is formed.

  A seal ring 40 made of an elastic material such as rubber, preferably silicone rubber (silicone rubber), is fixed to the fixed cylindrical portion 41 that is fitted to the small-diameter outer cylindrical surface 18 of the fixed cylindrical member 15 and abuts against the seal surface facing surface 17. It has an annular elastic lip 42 that extends outward in the radial direction (radial direction) from the fixed cylindrical portion 41 and whose free end elastically contacts the annular seal surface 27 from the axial direction (thrust direction). 2 indicates the annular elastic lip 42 in a free state (not in elastic contact with the annular seal surface 27), and is shown by a solid line in FIG. Thus, the annular elastic lip 42 is pressed against the annular seal surface 27 and elastically deforms forward (leftward in the figure). Therefore, the seal ring 40 has the seal surface facing surface 17, the fixed cylindrical portion 41, and the annular shape at an inner position in the radial direction from the elastic contact portion in a state where the annular elastic lip 42 is elastically in contact with the annular seal surface 27. The elastic lip 42 forms an external communication annular groove 43 that is open radially outward. On the outer side in the radial direction of the external communication annular groove 43, a flange cylinder portion 26 of the rotary operation cylinder 25 is positioned, and the external communication annular groove 43 is communicated to the outside at the front end portion of the flange cylinder portion 26. A gap S is formed. The seal ring 40 is fixed to the fixed cylinder member 15 (small-diameter outer cylindrical surface 18) by, for example, fastening with an adhesive or the seal ring 40.

  In the drip-proof structure of the lens barrel having the above-described configuration, when water drops enter the external communication annular groove 43 from the gap S, the water drops accumulate in the external communication annular groove 43. In order for the accumulated water droplets to go inward from the seal ring 40, it must pass through the gap between the annular elastic lip 42 and the annular seal surface 27. However, since the annular elastic lip 42 is in elastic contact with the annular seal surface 27 and the external communication annular groove 43 is radially inward from the elastic contact position between the annular elastic lip 42 and the annular seal surface 27, the pressure of the water droplets Is not applied (continuously applied) to the contact portion between the annular elastic lip 42 and the annular seal surface 27. Water droplets that have entered from the clearance S above the external communication annular groove 43 flow (wrap around) through the annular groove 43 and flow out of the clearance S below the external communication annular groove 43, and also enter the external communication annular groove 43. Since the accumulated water droplets eventually evaporate and disappear, a reliable drip-proof effect can be obtained. On the other hand, the rotational resistance applied to the fixed operation cylinder 15 by the annular elastic lip 42 of the seal ring 40 can be made much smaller than that of the O-ring, and a preferable operational feeling can be obtained.

  3 and 4 show another embodiment of the drip-proof structure according to the present invention. This embodiment differs from the first embodiment in that the shape of the seal ring 50 is different from that of the seal ring 40 and that the primary introduction groove 44 is formed separately from the external communication annular groove 43. The fixed cylinder member 15 is positioned between the large-diameter outer cylindrical surface 16 and the small-diameter outer cylindrical surface 18, and is formed with an intermediate-diameter outer cylindrical surface 16x having an intermediate diameter therebetween. A small outer flange 16y is formed at the end of the small-diameter outer cylindrical surface 18 side. The seal ring 50 includes a fixed disc portion 51 along the seal surface facing surface 17, a U-shaped portion 52 in which a radially inner end portion of the fixed disc portion 51 is folded outward, and the U-shaped portion. An annular elastic lip 53 that is continuous with the outer circumferential annular groove 43 is formed by the fixed disk portion 51, the U-shaped portion 52, and the annular elastic lip 53. Yes. Similar to the first embodiment, the annular elastic lip 53 is in elastic contact with the annular seal surface 27 of the rotary operation cylinder 25, and the elastic contact position is a radially outward position from the bottom of the external communication annular groove 43. It is in.

  Further, the seal ring 50 is fixed from the radially outer end portion of the fixed disc portion 51 to extend on the medium-diameter outer cylindrical surface 16x across the small outer flange 16y (extends on the opposite side to the annular elastic lip 53). A cylindrical portion 54 is provided, and a primary introduction groove 44 is formed between the medium-diameter outer cylindrical surface 16 x and the end of the fixed cylindrical portion 54. The fixed disk portion 51 and the fixed cylindrical portion 54 are fixed by, for example, fastening with an adhesive or the seal ring 50. The rod-shaped cylindrical portion 26 extends radially outward of the primary introduction groove 44, and a gap S is formed between the front end portion thereof and the rear end portion of the large-diameter outer cylindrical surface 16 of the fixed cylindrical member 15. Has been.

  In this embodiment, the sealing action by the fixed disk portion 51 of the seal ring 50, the U-shaped portion 52 and the external communication annular groove 43 formed by the annular elastic lip 53, and the annular elastic lip 53 and the annular seal surface 27 is This is the same as in the first embodiment. In addition, since the primary introduction groove 44 is provided on the inlet side of the water droplet from the external communication annular groove 43, the water droplet entering from the gap S first enters the primary introduction groove 44. For this reason, the amount of water droplets that enter the external communication annular groove 43 is limited as compared with the first embodiment, and thus a more preferable sealing property (drip-proof property) is obtained.

  In the above embodiment, the primary introduction groove 44 is formed by the end surface of the seal ring 50 and the medium-diameter outer cylindrical surface 16x. However, the primary introduction groove 44 can also be formed on the outer surface of the rotary operation cylinder 25 without using the seal ring. Further, the relationship between the fixed cylinder member 15 and the rotation operation cylinder 25 in the above embodiment may be a two-cylindrical member that relatively rotates, and the fixing side and the rotating side may be reversed. Although the annular seal surface 27 and the seal surface facing surface 17 are surfaces orthogonal to the optical axis O, the present invention is established as long as the extended surface intersects the optical axis even if they are not strictly orthogonal. .

O Optical axis 10 Fixed barrel 11 Annular groove 12 Cam groove (lead groove)
13 Mount ring 15 Fixed cylinder member (the other cylindrical member)
16 Large-diameter outer cylindrical surface 16x Medium-diameter outer cylindrical surface 16y Small-outer flange 17 Seal surface facing surface 18 Small-diameter outer-cylindrical surface 19 Stepped recess 20 Rotating lens barrel 21 Inner flange 22 Cam groove 25 Rotating operation cylinder (one cylindrical member)
26 庇 Cylindrical portion 27 Annular seal surface 30 Straight traveling barrel 31 Cam follower 40 Seal ring 41 Fixed cylindrical portion 42 Annular elastic lip 43 External communication annular groove 44 Primary introduction groove 50 Seal ring 51 Fixed disk portion 52 U-shaped portion 53 Annular Elastic lip 54 Fixed cylindrical part

Claims (8)

A drip-proof structure between two cylindrical members that rotate relative to each other without relative movement in the axial direction,
An annular seal surface formed on one of the two cylindrical members and having an extended surface intersecting the axis, and a seal ring made of an elastic material fixed to the other cylindrical member;
The seal ring has an annular elastic lip that elastically contacts the annular seal surface from the axial direction,
The seal ring is further characterized in that an external communication annular groove is formed in the radially inner position from the elastic contact position with the annular seal surface of the annular elastic lip so that the radially outer side communicates with the outside of the cylindrical member. Drip-proof structure of lens barrel. 2. The drip-proof structure for a lens barrel according to claim 1, wherein the other cylindrical member is connected to an outer cylindrical surface and one end portion of the outer cylindrical surface, and faces the annular sealing surface of the one cylindrical member. And the seal ring includes a fixed cylindrical portion fixed in contact with the outer cylindrical surface and the seal surface opposing surface, and the annular elastic lip extending radially outward from the fixed cylindrical portion. The external communication annular groove has a drip-proof structure for a lens barrel formed by a fixed cylindrical portion of the seal ring, an annular elastic lip, and a seal surface facing surface of the other cylindrical member. 2. The drip-proof structure for a lens barrel according to claim 1, wherein the other cylindrical member has a seal surface facing surface that faces an annular seal surface of the one cylindrical member, and the seal ring has the seal surface. A fixed disk portion along the opposing surface, a U-shaped portion in which a radially inner end portion of the fixed disk portion is folded outward, and the annular elastic lip continuous to the U-shaped portion. The outer communication annular groove is a drip-proof structure of the lens barrel formed by the fixed disk portion, the U-shaped portion and the annular elastic lip of the seal ring. 4. A drip-proof structure for a lens barrel according to claim 3, wherein the seal ring is connected to the fixed disk portion, extends to the opposite side of the annular elastic lip, and is fixed to the other cylindrical member. A drip-proof structure of a lens barrel having a fixed cylindrical portion. 5. The drip-proof structure of the lens barrel according to claim 1, wherein the one cylindrical member has a flange cylindrical portion positioned radially outward of the external communication annular groove. 6. Drip-proof structure of the lens barrel. 6. The drip-proof structure for a lens barrel according to claim 5, wherein the other cylindrical member includes an annular primary on the side farther from the annular elastic lip than the outer communicating annular groove, in addition to the outer communicating annular groove. A drip-proof structure of the lens barrel in which the introduction groove is formed. The drip-proof structure for a lens barrel according to any one of claims 2 to 6, wherein the annular seal surface and the seal surface facing surface are both axial orthogonal surfaces. 8. A drip-proof structure for a lens barrel according to claim 1, wherein the seal ring is made of silicone rubber.

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