JP5470899B2 - Drip-proof structure of lens barrel - Google Patents

Description

  The present invention relates to a drip-proof structure between annular members of a lens barrel.

The lens barrel generally includes a plurality of annular members that are concentric with each other and can be relatively moved along the optical axis or relatively rotated around the optical axis. When one of these annular members is used as a zoom operation ring or a manual focus ring, and the other annular member is advanced or retracted along the optical axis by manually rotating the zoom operation ring or the manual focus ring (adjacent to the radial direction) Conventionally, a photographer can feel an appropriate resistance when manually operating a zoom operation ring or a manual focus ring by intentionally generating a frictional resistance between the annular members. .
As an example of means for producing such a feeling of resistance, the other surface of the annular synthetic leather in which fine hairs are planted on one entire surface is fixed to the outer peripheral surface or inner peripheral surface of the annular member, and the synthetic leather One surface (flocked surface) of this is slidably brought into contact with the inner peripheral surface or outer peripheral surface of another adjacent annular member.

  However, when synthetic leather is used in this way, the photographer can feel an appropriate resistance, but water drops, dust, and the like can enter the lens barrel from the gap between adjacent annular members. It becomes difficult to prevent (provide a drip-proof effect).

For example, Patent Documents 1 and 2 disclose lens barrels that enable the photographer to feel resistance when manually operating the zoom operation ring or the manual focus ring while exhibiting a drip-proof effect.
In the lens barrel of Patent Document 1, the rear end portion of the outer peripheral surface of the front exterior ring and the position immediately after the front exterior ring are rotatable relative to the front exterior ring around the optical axis (relative movement in the optical axis direction). An annular washer made of plastic sheet or vinyl chloride sheet is inserted between the front end of the inner surface of the manual ring, and the manual ring is positioned at the rear end of the manual ring and immediately after the manual ring. An annular washer made of a plastic sheet or a vinyl chloride sheet is inserted between the front end of the inner peripheral surface of the rear exterior ring. Further, a water-repellent material is filled between the rear end portion of the outer peripheral surface of the front outer ring and the front end portion of the inner peripheral surface of the manual ring, and the rear end portion of the outer peripheral surface of the manual ring. The water repellent material is filled in a manner located immediately before the washer between the front end portion of the inner peripheral surface of the rear exterior ring.

  In the lens barrel of Patent Document 1 having such a structure, the washer and the front and rear water-repellent materials exhibit a drip-proof effect, so that water droplets and dust outside the lens barrel are prevented from entering the lens barrel. The In addition, since the washer is sandwiched between the front exterior ring and the manual ring and the washer is sandwiched between the manual ring and the rear exterior ring, the photographer resists when the photographer rotates the manual ring. You can feel the feeling.

  In the lens barrel described in Patent Document 2, a concentric groove is provided on the end surface in the optical axis direction of the focus operation ring, and the groove is filled with viscous grease (water repellent material or oil). A concentric convex ring portion that is loosely inserted into a groove portion provided in the focus operation ring is provided on the end surface of the ring facing the focus operation ring in the optical axis direction.

  In Patent Document 2, with this structure, the exterior ring and the focus operation ring are blocked by grease to prevent entry of water droplets and dust from the outside, and the type of grease is selected by viscosity By doing so, it is also possible to change the operating torque (resistance feeling) of the focus operation ring.

JP 2000-227534 A JP 2003-202481 A

  However, the lens barrel of Patent Document 1 uses a relatively hard material such as a plastic sheet or a vinyl chloride sheet to form an annular washer. Difficult to put out. In particular, when the annular member rotates around the optical axis while sliding in the optical axis direction, synthetic leather is used compared to when the annular member only slides around the optical axis direction or only around the optical axis. It is even more difficult to feel resistance like time. Furthermore, since the washer is formed of a plastic sheet or a vinyl chloride sheet, if there are minute irregularities on the surface of the washer, the rotation of the manual ring may become unsmooth due to the influence of the irregularities. As described above, the washer needs to be accurately molded according to the design shape, but it is not easy to accurately form the washer using a plastic sheet or a vinyl chloride sheet.

  Since the lens barrel of Patent Document 2 is drip-proof by the outer ring and the convex ring formed on the end face in the optical axis direction of the focus operation ring and the grease filled in the groove, the diameter of the outer ring and the focus operation ring It was not applicable if they were not identical.

  Furthermore, since Patent Document 2 has a structure in which the resistance (operating torque) changes and the drip-proof effect changes depending on the strength of the pressure sandwiching the light shielding member between the two lens barrels, if the pressure is weakened to reduce the resistance, it is prevented. On the other hand, if the drip effect is too small, and if the drip-proof effect is increased by increasing the pressure, the resistance becomes too high, and there is a problem that it is difficult to adjust the drip-proof performance and resistance.

  According to the present invention, when one of a plurality of drive system annular members that can be independently rotated is rotated, an appropriate operational feeling can be felt, and the other drive system annular member can be drawn and rotated. It is an object of the present invention to provide a lens barrel drip-proof structure that is easy to manufacture.

The present invention that solves the above-described problem has a plurality of annular members that can rotate relative to each other while being coaxial with each other, and the plurality of annular members are a pair of drive system rings that are independently rotatable relative to each other inside and outside and member, positioned on the inner circumferential side of the pair of the drive system the annular member, the lens barrel in which the pair of driving systems annular member comprises a pair of inner annular member to rotate relative respectively, a pair of inner annular Any one of the members is a fixed annular member whose rotation is constrained (the pair of drive system annular members is composed of an inner drive system annular member located on the inner side and an outer drive system annular member located on the outer side. The inner drive system annular member and one end of the outer drive system annular member are positioned so as to overlap each other in the radial direction, and the one end overlap portion includes the inner drive system annular member and the outer drive system annular member. Close the annular gap between The frictional sealing member is provided, and wherein by positioning an end portion side of the one end overlapped ends from the small friction sealing member, the drainage of more than one along the small friction sealing member on the outer peripheral surface of the inner drive system annular member A large friction sealing member that closes an annular gap between the annular members between the outer drive system annular member and the fixed annular member located on the inner peripheral side of the outer drive system annular member. the provided things, and when the inner drive system annular member is rotated, the frictional resistance of said small friction sealing member which tends to rotate by pulling in the outer driving system annular member, said outer drive system annular member It is smaller than the frictional resistance of the large friction sealing member acting between the fixed annular member and the fixed annular member rotating relative to each other.

Preferably, it is formed between the two bank portions projecting on the outer peripheral surface of the inner drive system annular member. More preferably, the outer drive system annular member is provided with a flange portion that extends to above the drainage groove and covers the drainage groove. Providing the drainage groove makes it difficult for water droplets or the like to reach the sealing member, and increases the degree of freedom for adjusting the frictional resistance by the sealing member.

  According to the present invention, when one of a plurality of drive system annular members that can be rotated independently is rotated, the other drive system annular member is not drawn and rotated. A drip-proof structure is obtained. Since the dependency on the drip-proof effect by the sealing member is low, adjustment of the rotational resistance by the sealing member is facilitated, and a plurality of drive system annular members can be set to rotate easily and independently.

1 is a cross-sectional view of an embodiment of a zoom lens barrel to which the present invention is applied, cut vertically along a plane passing through an optical axis. It is sectional drawing which showed the upper half from the optical axis by carrying out a longitudinal cut in the surface which passes along an optical axis in the state which adjusted the focus to the short distance of the zoom lens barrel. FIG. 4 is a cross-sectional view showing the upper half and the lower half of the zoom lens barrel in the tele end and wide end zoom states of the zoom lens barrel vertically cut by a plane passing through the optical axis. It is sectional drawing which expands and shows the drip-proof structure of the zoom lens barrel. It is sectional drawing which expands the upper half from an optical axis and shows the drip-proof structure of the zoom lens barrel. It is sectional drawing which expands the upper half from an optical axis and shows the drip-proof structure of the zoom lens barrel. It is a cross-sectional view showing the shape of the drip-proof drainage groove of the zoom lens barrel crossing along the cutting line VII-VII in FIG.

  Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a cross-sectional view of an embodiment of a zoom lens barrel to which the present invention is applied, taken longitudinally along a plane passing through the optical axis.

  The lens barrel 10 is an interchangeable lens zoom lens barrel including two lens groups L1 and L2. At the rear end portion of the first fixed ring 11 that is a cylindrical body centered on the optical axis O of each lens group L1, L2, a mount portion 12 that is detachable from the mount portion of the camera body (not shown) is provided. ing. Further, a second fixed ring 13 which is a cylindrical body concentric with the first fixed ring 11 is disposed on the inner peripheral side of the first fixed ring 11, and the rear end portion of the second fixed ring 13 is A fixed ring 11 is fixed to the front surface of the rear wall.

Zoom operation rings 15 and 17, which are cylindrical bodies concentric with the first fixed ring 11 and the second fixed ring 13, can rotate around the optical axis O (in the direction of the optical axis O). Is not possible). A zoom operation ring 17 is connected to the front end portion of the zoom operation ring 15 so as to rotate integrally. A grip ring 16 is fixed to the outer peripheral surfaces of these zoom operation rings 15 and 17. These zoom operation rings 15 and 17 constitute one of a plurality of drive system annular members. The first fixed ring 11 constitutes a fixed annular member on which the zoom operation rings 15 and 17 as outer drive system annular members rotate relative to each other.

On the outer peripheral surface of the front end portion of the first fixed ring 11, the rear end portion of the focus ring 19, which is a cylindrical body concentric with the first fixed ring 11, is in a state where movement in the optical axis O direction is restricted. It is provided so as to be rotatable around the axis O. The rear end of the focus ring 19 is located on the inner peripheral side of the zoom operation rings 15 and 17. Although not shown, a gear is formed at the rear end of the inner peripheral surface of the focus ring 19, and this gear is rotatably supported near the front end of the outer peripheral surface of the second fixed ring 13. Are engaged. When the lens barrel 10 is mounted on the camera body, the output gear is connected to a focusing motor built in the camera body via a gear mechanism built in the camera body. The focus ring 19 constitutes one of a plurality of drive system annular members, and is an inner drive system annular member positioned radially inward with respect to the zoom operation rings 15 and 17.

  A cam ring 21 that is a cylindrical body concentric with the second fixed ring 13 is disposed on the outer peripheral side of the second fixed ring 13. The cam ring 21 is supported so as to freely rotate around the optical axis O without moving the optical axis O with respect to the second fixed ring 13, and is further connected to the zoom operation ring 15 via the zoom interlocking lever 18. Has been. Therefore, when the zoom operation ring 15 rotates, the cam ring 21 rotates around the optical axis O without moving in the optical axis O direction.

  The second fixed ring 13 supports a second group support frame 23 located on the inner peripheral side of the cam ring 21. The second group support frame 23 is a member that supports the second lens group L2 that is a variator lens group, and is linearly guided by a straight guide groove formed in the second fixed ring 13, and is formed on the inner peripheral surface of the cam ring 21. The cam is connected to the cam groove. Accordingly, when the cam ring 21 rotates through the zoom operation ring 15, the second group support frame 23 does not rotate around the optical axis O, but at a speed according to the cam groove lead of the cam ring 21. Move forward and backward along.

  A rectilinear ring 25, which is a cylindrical body concentric with the cam ring 21, is fitted to the outer peripheral surface of the distal end portion of the cam ring 21. Although not described in detail, the rectilinear ring 25 is supported so as to advance and retract along the optical axis O without rotating to the second fixed ring 13 and rotates when the cam ring 21 is rotated by the cam mechanism between the cam ring 21 and the cam ring 21. Instead, they are connected so as to advance and retract along the optical axis O.

  Between the rectilinear ring 25 and the focus ring 19, a rotation feeding ring 27 which is a cylindrical body concentric with these is disposed. Although not described in detail, the rotary payout ring 27 is connected to the rectilinear ring 25 by a cam mechanism, and can move forward and backward in the direction of the optical axis O with respect to the focus ring 19 and rotate integrally around the optical axis O. It is connected. Therefore, when the cam ring 21 rotates, the rotation feeding ring 27 advances and retreats without rotating together with the rectilinear ring 25 that advances and retreats along the optical axis O by the cam mechanism between the rotation ring 27 and the cam ring 21. On the other hand, when the focus ring 19 rotates, the rotation extension ring 27 moves forward and backward along the optical axis O by a cam mechanism between the rotation ring 25 and the rectilinear ring 25 while rotating integrally with the focus ring 19. The rotation feeding ring 27 constitutes an annular member in which the drive system rotation member rotates relative to the rotation delivery ring 27.

  In the front end portion of the second fixed ring 13, the rear end portion of the first group support frame 29, which is a cylindrical body that supports the first lens group L1, is connected so as to be linearly movable in the direction of the optical axis O without rotating. Yes. It functions as a first lens unit L1, a compensator lens, and a focusing lens. The first group support frame 29 is connected on the outer periphery of the front end portion thereof so as to be relatively rotatable with respect to the rotation feeding ring 27 and to move together in the optical axis O direction. Accordingly, when the focus ring 19 is rotated, the rotation feeding ring 27 moves forward and backward, and the first group support frame 29 supports the first lens group L1 by this forward and backward movement, so that the optical axis O does not rotate. Move forward and backward along. On the other hand, when the zoom operation ring 15 is rotated, the first group support frame 29 is lighted with respect to the second fixed barrel 13 and the focus ring 19 by the rectilinear ring 25 and the rotation extension ring 27 in a state where the rotation is restricted. Move back and forth in the direction of axis O. FIG. 2 shows a state in which the focus ring 19 is rotated so that the rotation feeding ring 27, the first group support frame 29, and the first lens group L1 are moved forward most.

  Here, when the cam ring 21 rotates and the rectilinear ring 25 advances and retracts, the rotation feeding ring 27 advances and retracts without rotating, and when the focus ring 19 rotates, the rotation feeding ring 27 rotates and advances and retracts. It is formed to do.

When the cam ring 21 rotates, the second group support frame 23 holds the second lens group L2 by the cam mechanism lead between the cam ring 21 and the second group support frame 23. The first group support frame 29 holds the first lens group L1 without rotating along the straight guide groove, and the cam mechanism between the straight ring 25 and the cam ring 21 holds the first lens group L1. It moves forward and backward without rotating and is zoomed ( Fig. 3) .

  Next, a drip-proof structure provided between the rotation feeding ring 27 and the first group support frame 29, between the front zoom operation ring 17 and the focus ring 19, and between the rear zoom operation ring 15 and the first fixed ring 11. Will be further described with reference to FIGS.

  FIG. 4 is an enlarged cross-sectional view showing a drip-proof structure between the rotary feeding ring 27 and the first group support frame 29. A lasha 31 as a sealing member is bonded between the front inner peripheral surface of the rotary feeding ring 27 and the outer peripheral surface of the first group support frame 29. The lashers 31 are formed in an annular shape, are adhered to the outer peripheral surface of the first group support frame 29, and are in slidable contact with the rotary feeding ring 27, but the reverse is also possible. In addition, the sealing member is not limited to the rasha, such as an annular synthetic leather in which fine hairs are planted on the entire surface.

  On the outer peripheral surface of the first group support frame 29, a drainage groove 29 a regulated by the bank portions 29 b and 29 c is formed on the outer side of the lens barrel from the rasha 31, here at a position slightly separated from the front end surface of the rasha 31. Has been. The bank portions 29 b and 29 c, that is, the drainage grooves 29 a are formed over the entire circumference of the first group support frame 29. The bank portions 29b and 29c are formed higher on the front (outside) bank portion 29b.

  At the front end portion of the rotary feeding ring 27, a flange portion 27a that covers the drainage groove 29a is formed. The eaves part 27a extends beyond the outer peripheral surface of the rear bank part 29c to a position where it covers the drainage groove 29a and leaves a slight gap with the front bank part 29b. Further, the flange portion 27a is formed with a tapered portion 27a1 which is inclined on the surface facing the drainage groove 29a in a direction in which a gap or a gap with the bottom of the drainage groove 29a increases toward the tip.

  Since the drainage groove 29a having such a flange portion 27a is provided outside the rasha 31, first, water droplets that have fallen on the lens barrel enter the drainage groove 29a from the gap between the flange portion 27a and the bank portion 29b. Although entering, the water droplets that have entered the drainage groove 29a flow downward in the direction of gravity along the drainage groove 29a, and fall out of the drainage groove 29a through the gap between the lower flange portion 27a and the bank portion 29b. That is, when a water droplet starts falling with the camera held in the normal position, the water droplet travels through the drainage groove 19a and falls outside the lens barrel. Furthermore, in this embodiment, since the lower flange portion 27a is inclined in a direction in which the tapered portion 27a1 is lowered toward the gap with the drainage groove 29a, the drainage capacity is increased.

  FIG. 5 is an enlarged cross-sectional view showing a drip-proof structure between the front zoom ring 17 and the focus ring 19. Between a front end inner peripheral surface of the front zoom ring 17 and an outer peripheral surface of the focus ring 19, a lasha 33 as a sealing member is bonded. The lasher 33 is adhered to the outer peripheral surface of the focus ring 19 and is in slidable contact with the inner peripheral surface of the front zoom ring 17, but the reverse is also possible.

The outer peripheral surface of the focus ring 19 is regulated by the bank portions 19b and 19c on the outer side of the lens barrel of the zoom ring 17 in front of the rasha 33, here at a position slightly separated from the front end surface of the rasha 33. A drainage groove 19a is formed. The bank portions 19b and 19c, that is, the drainage grooves 19a are formed over the entire circumference of the focus ring 19. The bank portions 19b and 19c are formed higher in the front bank portion 19b.
At the front end portion of the front zoom ring 17, a flange portion 17a that covers the drainage groove 19a is formed. The flange portion 17a extends beyond the outer peripheral surface of the rear bank portion 19c to a position where it covers the drainage groove 19a and leaves a slight gap with the upper surface of the front bank portion 19b.

  Since the drainage groove 19a having such a flange portion 17a is provided on the outer side of the rasha 33, the water droplets that have fallen on the lens barrel first enter the drainage groove 19a from the gap between the flange portion 17a and the bank portion 19b. Although entering, the water droplets that have entered the drainage groove 19a flow downward in the direction of gravity along the drainage groove 19a, and fall out of the drainage groove 19a through the gap between the lower flange portion 17a and the bank portion 19b. That is, when a water droplet starts falling with the camera held in the normal position, the water droplet travels through the drainage groove 19a and falls outside the lens barrel.

  In addition, between the front end part of the focus ring 19 and the rotation feeding ring 27, drip-proofing is performed by a lasha 37 as a sealing member. The outer surface of the lasher 37 is bonded to the inner peripheral surface of the focus ring 19, and the inner peripheral surface is in slidable contact with the rotary feeding ring 27.

  FIG. 6 is an enlarged cross-sectional view showing a drip-proof structure between the rear zoom operation ring 15 and the first fixed ring 11. Between a rear end inner peripheral surface of the rear zoom operation ring 15 and an outer peripheral surface of the first fixed ring 11, a lasha 35 as a sealing member is bonded. The lasher 35 is bonded to the outer peripheral surface of the first fixed ring 11 and is in slidable contact with the inner peripheral surface of the zoom operation ring 15 at the rear, but the reverse may be possible.

  The outer peripheral surface of the first fixed ring 11 is restricted by the bank portions 11b and 11c on the outer side of the lens barrel of the zoom operation ring 15 at the rear part of the rear part 35, here slightly away from the rear end face of the rear part 35. A drainage groove 11a is formed. The bank portions 11 b and 11 c, that is, the drainage grooves 11 a are formed over the entire circumference of the first fixed ring 11. The bank portions 11b and 11c are formed higher in the front bank portion 11b. The rear bank portion 11 c is formed by the outer peripheral surface of the first fixed ring 11.

  At the rear end portion of the rear zoom operation ring 15, a flange portion 15a that covers the drainage groove 11a is formed. The flange portion 15a extends beyond the outer peripheral surface of the front bank portion 11b to a position where it covers the drainage groove 11a and leaves a slight gap with the rear bank portion 11c. Further, the flange portion 15a is formed with a tapered portion 15a1 whose surface facing the drainage groove 11a is inclined in a direction in which a gap or a gap with the bottom of the drainage groove 11a increases toward the tip.

  Since the drainage groove 11a having such a collar portion 15a is provided outside the lens barrel from the Rasha 35, the water droplets that have fallen on the lens barrel are first drained from the gap between the collar portion 15a and the bank portion 11c. Although it penetrates into the groove 11a, the water droplets that have entered the drain groove 11a flow downward along the drain groove 11a in the direction of gravity and fall out of the drain groove 11a through the gap between the lower flange portion 15a and the bank portion 11c. That is, when a water droplet starts falling with the camera held in the normal position, the water droplet travels through the drainage groove 11a and falls out of the lens barrel from the bottom. Here, the drainage groove 11a becomes shallower in the downward direction, and the taper portion 15a1 of the flange portion 15a is inclined in the direction in which the drainage groove 11a falls outside the drainage groove 11a (the gap is widened). It becomes easy to flow out of the drainage groove 11a along, and drainage capacity becomes high.

  Further, the drainage groove 11a is formed so that the upper part is deeper and the lower part is shallower with the lens placed in the normal position (FIG. 7). By changing the depth of the drainage groove 11a in this way, water droplets that have fallen on the lens barrel while being held at the normal position enter the upper drainage groove 11a and from the lower drainage groove 11a to the lens mirror. It becomes easy to fall out of the cylinder.

As described above, according to the drip-proof structure of the embodiment, the drainage grooves 29a, 11a, and 19a are provided at positions outside the lens barrel relative to the rasha 31, 33, and 35 that are sealing members that seal between the relatively rotating lens barrels. The water droplets first enter the drain grooves 29a, 11a and 19a, flow along the drain grooves 29a, 11a and 19a, and come out of the lens barrel, so that the drip-proof and waterproof effect is higher than with the sealing member alone.
According to the drip-proof structure provided with the flanges 27a, 17a, and 15a covering the drainage grooves 29a, 11a, and 19a, water droplets are blocked by the flanges 27a, 17a, and 15a, and are difficult to enter the drainage grooves 29a, 11a, and 19a. Since it flows down the lens barrel through the outer surfaces of the collar portions 27a, 17a, 15a, the drip-proof waterproof effect is further enhanced.
According to the drip-proof structure in which the depth of the drainage groove 19a is deeper in the upper position in the normal position and shallower in the lower part, when water droplets entering the drainage groove 19a flow downward along the drainage groove 19a, Since the bottom is shallow, it easily overflows from the drain groove 19a and drops out of the lens barrel, and the drip-proof waterproof effect is further enhanced.

The collar part may be either a shape that completely covers the drainage groove (the collar part 17a) or a shape that substantially covers the drainage groove (the collar parts 27a and 15a).
Although the taper portions 27a1 and 15a1 are formed on the flange portions 27a and 15a, it is preferable to provide a similar taper portion on the other flange portion 17a.
Two or more drainage grooves may be provided.

  The embodiment in which the drip-proof structure of the present invention is applied to the two-group zoom lens barrel has been described above, but the present invention is not limited to this embodiment and can be applied to other lens barrels.

  Next, operations when the zoom operation ring 15 and the focus operation ring 19 are rotated will be described with reference to FIGS.

"Focusing"
When the focus operation ring 19 is rotated, the rotation is transmitted to the rotation feeding ring 27, and the rotation feeding ring 27 rotates. Since the rotation feeding ring 27 is helicoid-connected to the rectilinear ring 25 guided in a straight line, it advances and retreats while rotating. By the advance and retreat of the rotation feeding ring 27, the first group support frame 29 and the first lens group L1 are integrally moved forward and backward along the optical axis O without rotating (FIG. 2).

  Here, a dash is prevented by a rusher 33 between the focus operation ring 19 and the front zoom operation ring 17. Accordingly, the rotational force of the focus operation ring 19 acts (rotation torque is generated) so as to rotate the zoom operation rings 15 and 17 via the frictional resistance between the rushers 33. Therefore, in this embodiment, the distance between the zoom operation ring 17 and the first fixed ring 11 is greater than the frictional resistance (rotational torque caused by the maximum static frictional force and sliding frictional force) between the focus ring 19 and the zoom operation ring 15. The frictional resistance maximum static friction amount of the Rasha 35 and the rotational torque due to the sliding friction force) are set larger. Due to the difference between the frictional resistance and the rotational torque, even if the focus operation ring 19 is rotated, the zoom operation rings 15 and 17 are not drawn and rotated.

"zooming"
When the zoom operation rings 15 and 17 are rotated, the rotation is transmitted to the cam ring 21 and the cam ring 21 rotates. When the cam ring 21 rotates, the rectilinear ring 25 connected to the cam ring 21 by the cam mechanism moves forward and backward without rotating. The rotary feeding ring 27 helicoidally connected to the rectilinear ring 25 moves forward and backward together with the rectilinear ring 25 without rotating. Accordingly, the first group support frame 29 and the first lens unit L1 move forward and backward together with the rotation feeding ring 27.

  Here, a drip-proof is provided between the front zoom operation ring 17 and the focus operation ring 19 by a rusher 33. Accordingly, the rotational force of the zoom operation ring 17 acts to rotate the focus operation ring 19 via the frictional resistance between the rushers 33. In this embodiment, therefore, the frictional resistance (rotational torque caused by the maximum static frictional force and sliding frictional force) between the focus ring 19 and the zoom operation ring 15 is less than the frictional force between the focus ring 19 and the rotation feeding ring 27. The frictional resistance (maximum static friction amount and rotational torque due to sliding frictional force) is set larger. Due to this difference in frictional resistance (rotational torque), even if the zoom operation rings 15 and 17 are rotated, the focus operation ring 19 is not drawn and rotated.

  As described above, according to the zoom lens barrel of the present embodiment, the frictional resistance caused by the dash between the focus ring 19 and the zoom rings 15, 17 that are relatively rotated independently of each other is prevented by the focus ring 19. And the rotation resistance ring 27 are set to be smaller than the frictional resistance due to the splasher 37 that prevents drip and between the zoom rings 15, 17 and the first fixed ring 11. 19. Even if one of the zoom operation rings 15 and 17 is rotated, the other is not pulled and rotated.

  Further, in the present embodiment, the drainage groove 19a, the bank portions 19b and 19c, and the flange portion 17a are provided in addition to the rasha 33 as a drip-proof structure of the zoom operation ring 17 and the focus operation ring 19 at the front portion. It is easy to adjust the frictional resistance to be small. Even if the pressure at which the rasha 33 comes into contact with the front zoom operation ring 17 is reduced so that the frictional resistance by the rasha 33 is reduced, a sufficient drip-proof effect can be obtained by the drainage grooves 19a, the bank portions 19b, 19c, and the flange portion 17a. Retained.

  In the present embodiment, the depth of each drainage groove 11a, 19a, 29a may be varied. Since the drip-proof ability can be varied by varying the depth of the drain grooves 11a, 19a, 29a, torque adjustment such as increasing the drip-proof capacity and reducing the frictional resistance of the sealing member becomes possible. The same effect can be obtained by changing the number of drain grooves.

10 Lens barrel 11 First stationary ring ( inner annular member , stationary annular member )
11a Drainage groove 11b Dyke part 11c Dyke part 12 Mount part 13 Second fixed ring 15 Zoom operation ring ( outer drive system ring member)
15a collar 17 front zoom operation ring ( outer drive system ring member)
17a collar 19 focus ring ( inner drive system ring member)
19a Drainage groove 19b Embankment 19c Embankment 23 Second group support frame 25 Straight ring 27 Rotating feed ring ( inner ring member)
27a ridge portion 29 first group support frame 29a drainage groove 29b levee portion 29c levee portion 31
33 Rasha (small friction sealing member)
35 Rasha (Large Friction Sealing Member)
37 Rasha (Large Friction Sealing Member)

Claims (3)

A plurality of annular members that can rotate relative to each other while being coaxial with each other, and the plurality of annular members are a pair of drive system annular members adjacent to the inside and outside that can independently rotate relative to each other, and the pair of drive system annular members. A pair of inner annular members , which are located on the inner peripheral side of the pair of drive system annular members, and each of the pair of drive system annular members rotate relative to each other .
Either one of the pair of inner annular members is a fixed annular member constrained to rotate,
The pair of drive system annular members includes an inner drive system annular member located on the inner side and an outer drive system annular member located on the outer side, and one end portion of the inner drive system annular member and the outer drive system annular member has a diameter. Being located in the direction superimposed,
The one end overlapping portion is provided with a small friction sealing member that closes an annular gap between the inner drive system annular member and the outer drive system annular member, and the small friction sealing is provided on an outer peripheral surface of the inner drive system annular member. One or more drainage grooves are provided at a position along the small friction sealing member by being positioned closer to the end of the one end overlapping end than the member,
The outer drive system annular member, between the stationary annular member located on the inner peripheral side of the outer driving system annular member, the provision of the large frictional sealing member for closing the annular gap between the annular member, and when the inner drive system annular member is rotated, the frictional resistance of said small friction sealing member which tends to rotate by pulling in the outer driving system annular member, said fixing rotating the outer driving system annular member relative Smaller than the frictional resistance of the large friction sealing member acting between the annular member,
A drip-proof structure for lens barrels. In water-resistant according to claim 1 Symbol placement of the lens barrel, the drainage groove is proof of the lens barrel formed between the two of the bank portion projecting from the drive system annular member outer peripheral surface of the inner Drop structure. 3. A drip-proof structure for a lens barrel according to claim 1 or 2 , wherein the outer drive system annular member is provided with a flange portion that extends above the drain groove and covers the drain groove. Drop structure.

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