JP2008151820A - Lens barrel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To clean a lens by ensuring smooth movement of a lens, as well as, making it splashproof and waterproof functions for a lens barrel, and by automatically removing dust sticking to the surface of the frontmost lens. <P>SOLUTION: The lens barrel, having the lens movable in the direction of an optical axis, includes vent holes 217 in the direction of the optical axis, formed in a holding section holding the very front lens L1 located on the subject side, the vent holes 217 used to allow communication between the inside and the outside of the lens barrel; and air-straightening means 5 and 7, formed opposite the front openings of the vent holes 217 and serving such that air circulating from the inside of the lens barrel to the outside of it through the vent holes 217 is guided toward the front face of the frontmost lens L1. When the lens is moved in the direction of the optical axis, the air blown from the inside of the lens barrel to the outside through the vent holes 217 is sprayed onto the face of the frontmost lens L1 by the air-straightening means 5 and 7 and the dust sticking to the face of the frontmost lens L1 is removed and the lens face is cleaned. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a lens barrel of a camera, and more particularly to a lens barrel having a cleaning structure for removing dust adhering to the surface exposed to the outside of a lens disposed on the foremost side (subject side) of the lens barrel. Is.

  The lens barrel of a camera has one or more lenses arranged in the optical axis direction inside a generally cylindrical barrel. Since the front surface of the lens closest to the subject (hereinafter referred to as the front lens in this specification) has a front surface exposed to the outside of the lens barrel, dust is likely to adhere to this surface, which affects photographing. It is necessary for the photographer to clean the surface of the front lens by removing it with a blower or the like periodically or when dust is attached. In particular, in recent years, lens barrels have been proposed that improve the water and water resistance of the lens barrel while ensuring air permeability inside and outside the lens barrel. The surface of the front lens in this type of lens barrel has been proposed. There is a problem of dust adhesion to the surface.

In other words, if the inside of the lens barrel is made liquid-tight in order to prevent moisture from entering the lens barrel and obtain a drip-proof / waterproof effect, the lens barrel can be moved when the lens is moved during zooming or focusing. A difference between the internal pressure and the external pressure generated with the change in the internal volume is generated, which hinders smooth movement of the lens. For this reason, there has been proposed a lens barrel that allows ventilation between the inside and outside of the lens barrel without impairing the drip-proof / waterproof effect. In Patent Document 1, a vent hole is provided in the lens holding frame of the front lens, and this vent hole is referred to as Gore-Tex (trademark), which is covered with a water-repellent microporous member that passes the vent but prevents the passage of moisture. The technique which provided the clearance gap between the appearance members which cover a water-repellent microporous member is proposed. According to Patent Document 1, while the water-repellent microporous member ensures the drip-proof / waterproof effect in the vent hole, the air can be moved inside and outside the lens barrel through the vent hole, thereby smoothly moving the lens. Is secured.
JP 2003-202480 A

  In Patent Document 1, when a plurality of lenses constituting a lens barrel are moved during zooming or focusing, when the internal volume of the lens barrel changes, particularly when the volume of the lens barrel decreases, the lens Smooth movement of the lens is ensured by discharging the air inside the lens barrel to the outside through the vent hole. At that time, the air that has passed through the vent hole and the water-repellent microporous member and is discharged to the outside of the lens barrel causes turbulent flow in the region near the surface of the front lens, and dust in the air caught in the turbulent flow is It becomes easy to adhere to the surface of the front lens. This is because, when the volume of the lens barrel increases, turbulence of air may occur near the surface of the front lens as well when air outside is sucked into the lens barrel through the vent hole. May adhere to the front lens surface.

  An object of the present invention is to clean the lens by automatically removing dust adhering to the surface of the front lens in a lens barrel that ensures drip-proofing and waterproofing of the lens barrel and ensuring smooth movement of the lens. The present invention provides a lens barrel that is made possible.

  The present invention is a lens barrel having a lens that is movable in the optical axis direction, and a holding member that holds the foremost lens located on the subject side is provided with a vent hole in the optical axis direction that communicates the inside and outside of the lens barrel. An air rectifier that guides air flowing from the inside of the lens barrel through the vent toward the front of the front lens is provided at a position facing the front opening of the vent. Here, the air rectifier is configured to guide air in a direction inclined in the optical axis direction with respect to the front surface of the front lens. The vent hole is provided with a waterproof ventilation material that allows air to pass but prevents moisture from passing therethrough.

  According to the present invention, when the lens is moved in the optical axis direction, the air in the lens barrel is sucked and discharged through the vent hole, so that the lens barrel does not become negative or positive pressure. Smooth movement becomes possible. In addition, the waterproof and air-permeable material provided in the vent hole can prevent moisture from entering the lens barrel, thereby improving waterproofness and dustproofness. Further, since the air blown out from the vent hole is projected onto the lens surface of the foremost lens by the air rectifying means and flows along the front surface, dust attached to the lens surface of the foremost lens can be removed, and the lens The surface can be cleaned, and at the same time, dust in the air is less likely to adhere to the lens surface of the front lens by rectification.

  As a preferred form of the lens barrel of the present invention, the vent hole is disposed at a peripheral position of the foremost lens, and the air rectifying means is constituted by an annular member extending along the peripheral edge of the foremost lens. For example, the vent hole is opened at at least one location in the circumferential direction, and the lens holding member communicates with the vent hole to be recessed in the optical axis direction, and extends in the circumferential direction. It is provided at a plurality of locations in the circumferential direction on the inner diameter side and includes notches connected to the inside of the groove, and the air rectifying means is configured to be provided at a position covering the front side of the groove and the notch, Air can be blown from the periphery of the front lens to the lens surface and further flowed from the periphery toward the center, so that a wide range of the lens surface can be effectively cleaned.

  The air rectifying means is constituted by a decorative ring for covering at least a part of the front surface of the lens barrel. The air rectification means can be configured using a decorative ring usually provided in the lens barrel, and the present invention can be applied to an existing lens barrel. In addition, a lens press ring for holding the peripheral edge of the front lens to the lens holding member is provided, and a minute gap directed toward the front surface of the front lens is provided between the lens press ring and the decorative ring. Constitute. The minute air gap increases the flow velocity of the air blown toward the front surface of the foremost lens, thereby enhancing the lens cleaning effect. Furthermore, the front lens can be moved in the optical axis direction, and a vent hole is opened in the lens holding member that holds the front lens, whereby the front surface of the lens can be effectively cleaned by the movement of the front lens.

  Next, Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view along an optical axis Ox of an embodiment in which the present invention is applied to a lens barrel having a two-group configuration, and FIG. 2 is a partially exploded perspective view of a main part of the lens barrel. A first lens L1 is provided as the foremost lens facing the subject side of the fixed ring 1 of the lens barrel, and a second lens L2 is provided behind it. The fixed ring 1 is composed of an outer ring 11 and an inner ring 12 concentrically connected at the rear end, and the second lens L2 is fixed to the rear end of the inner ring 12 by a second lens frame 22. It is supported by. A bayonet piece is provided at the rear end of the stationary ring 1 so that a lens barrel can be attached to and detached from a lens mount provided in the camera body. However, the illustration of the bayonet piece is omitted here. ing. A focus cam ring 3 is inserted between the outer ring 11 and the inner ring 12, and the focus cam ring 3 extends along the outer peripheral surface of the fixed ring 1 to adjust the focus of the lens barrel. A focus operation ring 4 that is rotated around the optical axis by a manual operation during (focus adjustment) is integrally provided. A straight rectilinear groove 121 extending in the optical axis direction is opened in the inner ring 12, and a cam groove 31 having a required shape is opened in the focus cam ring 3.

  Inside the inner ring 12, the first lens L1 is supported by a first lens frame 21 so as to be movable in the optical axis direction. The first lens frame 21 is formed in a substantially crank shape with a cross-sectional shape along the optical axis direction, and the outer peripheral surface of the front end portion 211 whose diameter is increased is the front end of the inner ring 12 whose diameter is increased. It is slidable in the optical axis direction while being in sliding contact with the inner peripheral surface of the portion 122. Further, rollers 212 protrude from the plurality of circumferential positions of the first lens frame 21 toward the outer shape direction, and the rollers 212 pass through the straight advance grooves 121 provided in the inner ring 12 in the optical axis direction. Further, the cam groove 31 of the focus cam ring 3 is passed through. As a result, when the focus cam ring 3 is rotated around the optical axis, the intersection position of the cam groove 31 and the linear groove 121 in the optical axis direction is changed, so that the roller 212 follows the shape of the cam groove 31. The first lens frame 21 that is integral with the roller 212, that is, the first lens L1, is moved in the optical axis direction within the rectilinear groove 121, and focus adjustment is performed.

  A seal ring 41 is provided on the inner peripheral surface of the focus operation ring 4 at a location that is in sliding contact with the outer peripheral surface of the front end portion 122 of the inner ring 12 to seal the two in an airtight and liquid-tight manner. Similarly, a seal ring 111 is provided on the outer peripheral surface of the outer ring 11 at a location where it comes into sliding contact with the inner peripheral surface of the focus operation ring 4, and seals the two in an air-tight and liquid-tight manner. Further, a seal ring 123 is provided on the inner peripheral surface of the front end portion 122 of the inner ring 12 at a location that is in sliding contact with the outer peripheral surface of the front end portion 211 of the first lens frame 21, so that both are airtight and liquid tight. It is sealed. Accordingly, the sliding contact portions of the focus operation ring 4, the fixed ring 1, and the first lens frame 21 are sealed by the seal rings 41, 111, and 123, whereby the inside of the lens barrel is connected to the outside. Airtightness is maintained in between, and moisture and dust are prevented from entering the lens barrel from the outside.

  FIG. 3 is a cutaway perspective view of the main part of the first lens frame 21. Referring to FIG. 3 as well, the first lens L1 is held in the first lens frame 21 in order to hold the first lens L1. An inner flange 213 is provided at the rear end portion of the frame 21, and a rear surface peripheral portion of the first lens L <b> 1 inserted from the front side of the first lens frame 21 is brought into contact with the inner flange 213. In addition, a lens press ring 5 having an annular shape on the inner surface is screwed into an inner diameter portion 214 of a step portion 215 that is continuous in the radial direction with the rear end of the front end portion 211 of the first lens frame 21. Thus, a configuration is adopted in which the front peripheral edge of the first lens L1 is sandwiched between the inner flange 213. The lens retainer ring 5 has a triangular cross-sectional shape, and in particular, the front surface 5a is formed to be an inclined surface inclined from the outer diameter side toward the inner diameter side.

  Further, a concave groove 216 that is recessed in the optical axis direction is formed in an annular shape along the circumferential direction on the front surface of the step 215 of the first lens frame 21 in the optical axis direction. A plurality of vent holes 217 penetrating the step 215 in the optical axis direction are opened at a plurality of locations in the circumferential direction of the bottom surface of the base plate. Further, on the inner peripheral side of the concave groove 216, a plurality of notches 218 are provided at a plurality of locations corresponding to the plurality of vent holes 217 so as to communicate the concave groove 216 toward the inner diameter side region. A waterproof ventilation plate 6 in the shape of an annular plate having the same diameter as the concave groove 216 is attached to the bottom surface of the concave groove 216 with an adhesive or the like. The waterproof ventilation plate 6 is formed of a material that allows air to pass therethrough but does not allow moisture to pass therethrough like the Gore-Tex described above.

  Further, a decorative ring 7 is screwed onto the inner peripheral surface of the front end portion 211 of the first lens frame 21, and the concave groove 216 formed in the step 215 of the first lens frame 21 through the decorative ring 7 passes through. The region covering the air holes 217, the notches 218, and the waterproof ventilation plate 6 is covered to enhance the appearance. The decorative ring 7 has a substantially triangular cross-sectional shape, a front surface 7a inclined toward the inner diameter is decorated in a staircase shape, and a rear surface 7b substantially perpendicular to the optical axis is the first lens frame 21. The step portion 215 is in close contact with the front end surface. Further, the inner edge portion 71 of the decorative ring 7 extends to a position close to the outer diameter edge of the lens pressing ring 5. In the first embodiment, the decorative ring 7 alone or together with the lens pressing ring 5 constitutes an air rectifying means for rectifying the flow of air flowing through the vent hole 217.

  In this lens barrel, when focus adjustment is performed, when the focus operation ring 4 is manually rotated, the focus cam ring 3 integrated therewith is rotated around the optical axis. As a result, as shown in FIG. 4, the intersection of the cam groove 31 of the focus cam ring 3 and the linear groove 121 of the inner ring 12 is changed, so that the roller 212 moves in the rectilinear groove 121 along with the shape of the cam groove 31. The first lens frame 21 integrated with the roller 212, that is, the first lens L1, is moved in the optical axis direction, and the focus adjustment is performed. At this time, when the first lens L1 moves away from the second lens L2, that is, in front of the lens barrel, the distance between the first lens L1 and the second lens L2 becomes longer, and the first lens in the lens barrel is increased. The volume between L1 and the second lens L2 is increased. Further, when the first lens L1 moves toward the second lens L2, that is, rearward of the lens barrel, the distance between the first lens L1 and the second lens L2 in the optical axis direction is shortened, and the inside of the lens barrel is reduced. The volume between the first lens L1 and the second lens L2 is reduced.

  When the volume in the lens barrel is increased by moving the first lens L1 to the front of the lens barrel, the outside air of the lens barrel is the inner end of the decorative ring 7 as shown by the broken line arrow in FIG. It passes through the gap between the portion 71 and the front surface 5a of the lens pressing ring 5 and flows into the concave groove 216 through the decorative ring 7 and the cutout portion 218 of the first lens frame 21, and passes through the waterproof ventilation plate 6 from the concave groove 216. Then, the air is sucked into the lens barrel through the vent hole 217. At this time, external moisture does not enter the lens barrel by the waterproof ventilation plate 6. At the same time, the waterproof ventilation plate 6 prevents external dust from entering the lens barrel. This ensures air circulation inside and outside the lens barrel as the first lens L1 moves, so that no negative pressure is generated inside the lens barrel, and the focus adjustment by the first lens L1 is performed smoothly. Thus, the light operation of the focus operation ring 4 becomes possible.

  On the other hand, when the first lens L1 is moved rearward of the lens barrel and the volume in the lens barrel is reduced, the air inside the lens barrel is vented 217 as shown by the solid arrow in FIG. , Passes through the waterproof ventilation plate 6 and flows into the concave groove 216, flows along the circumferential direction in the concave groove 216, passes through the notches 218 at a plurality of circumferential positions, and passes through the decorative ring 7 and the lens. The air is exhausted outside the lens barrel through a gap with the presser ring 5. Thus, the air pressure in the lens barrel does not increase with the movement of the first lens L1, the focus adjustment by the first lens L1 is performed smoothly, and the focus operation ring 4 can be operated easily. .

  At this time, the air in the lens barrel is exhausted to the outside of the lens barrel as described above, but the inner edge portion 71 of the decorative ring 7 is in a position close to the front surface 5a of the lens pressing ring 5, and Since the front surface 5a of the lens pressing ring 5 is formed as an inclined surface that is inclined toward the lens surface of the first lens L1, air exhausted from the notch 218 of the concave groove 216 is directed to the front surface 5a of the lens pressing ring 5. A direction along the inclination, that is, the lens surface of the first lens L1 is blown out from the outer peripheral oblique direction. The blown air is projected onto the lens surface of the first lens L1, and then flows toward the center along the lens surface. At this time, dust attached to the lens surface of the first lens L1 can be removed by the air flow, and the lens surface can be cleaned. In addition, since the air blown to the lens surface of the first lens L1 in this manner is rectified in a centripetal manner from the outer periphery toward the center, a region along the lens surface of the first lens L1 As a result, air turbulence does not occur and dust in the air hardly adheres to the lens surface of the first lens L1.

  As described above, in the first embodiment, particularly when the first lens L1 is moved rearward in the optical axis direction, the focus operation ring 4 can be smoothly operated, while the air in the lens barrel is changed. Through the ventilation hole 217-waterproof ventilation plate 6-concave groove 216-notch 218, and further projected from the gap between the decorative ring 7 and the lens pressing ring 5 toward the lens surface of the first lens L1, the lens surface Dust adhering to can be removed and cleaned.

  Here, as shown in FIG. 5, the inner edge 71 of the decorative ring 7 is extended to a position covering the outer diameter side region of the front surface 5a of the lens pressing ring 5, and a gap d having a required length is formed between the two. You may make it do. In this way, the air blown out from the lens barrel through the concave groove 216 or the notch 218 passes through the minute gap d formed by the decorative ring 7 and the lens pressing ring 5 by the Bernoulli effect. Is increased and is projected onto the lens surface of the first lens L1 at a high flow velocity, and the dust removal effect can be enhanced.

  Although not shown, the cutout portions 218 formed in the concave groove 216 may be provided in a larger number than the vent holes 217 and arranged at equal intervals in the circumferential direction. The air that has flowed up to the groove 216 may be made uniform in the circumferential direction in the concave groove 216 and then blown out from a large number of locations in the circumferential direction toward the lens surface of the first lens L1. Air can be projected onto the entire area of the lens surface of the first lens L1 without any gap, and the dust removal effect is enhanced. On the contrary, the number of the notches 218 formed in the concave groove 216 may be smaller than the number of the air holes 217. In this case, since the force of blowing air becomes large, it is possible to remove even dust with strong adhesion.

  In the first embodiment, the first lens corresponding to the forefront lens of the present invention is moved in the optical axis direction. However, the first lens is also applied to a lens barrel having a configuration in which the second lens is fixed and moved. be able to. In addition, a lens barrel including one lens or one or more groups of lenses can be used to reduce a load when the volume in the lens barrel changes by moving any of the lenses in the optical axis direction. The present invention can be similarly applied to any lens barrel provided with air holes in the front surface of the lens barrel.

  In the first embodiment, the first lens is a lens barrel of a lens for focus adjustment. However, the present invention can be similarly applied to a lens barrel configured as a lens for zooming adjustment.

1 is a partial cross-sectional view of a lens barrel of Embodiment 1 of the present invention. 1 is an exploded perspective view illustrating a schematic configuration of a main part of Example 1. FIG. It is a fractured perspective view of the principal part of the 1st lens frame. It is sectional drawing similar to FIG. 1 of the state which moved the lens. It is sectional drawing of the principal part of the modification of a decorative ring.

Explanation of symbols

1 fixed ring 3 forecam cam ring 4 focus operating ring 5 lens presser ring (air rectifying means)
6 Waterproof ventilation plate 7 Cosmetic ring (air rectification means)
11 outer ring 12 inner ring 21 first lens frame 22 second lens frame 31 cam groove 121 rectilinear groove 212 roller 216 concave groove 217 vent hole 218 notch L1 first lens L2 second lens

Claims (9)

  A lens barrel having a lens movable in the optical axis direction, the lens holding member holding the foremost lens located on the subject side, provided with a vent hole in the optical axis direction communicating with the inside and outside of the lens barrel, A lens barrel comprising air rectification means for guiding air flowing from the inside of the lens barrel through the vent toward the front of the front lens at a position facing the front opening of the pore.   The lens barrel according to claim 1, wherein the air rectifying unit is configured to guide air in a direction inclined in an optical axis direction with respect to a front surface of the foremost lens.   The lens barrel according to claim 1, wherein a waterproof ventilation member is provided in the vent hole so that air passes but prevents moisture from passing therethrough.   4. The air vent is disposed at a peripheral position of the foremost lens, and the air rectifying means is an annular member extending along a peripheral edge of the foremost lens. The lens barrel according to any one of the above.   The vent hole is opened at at least one location in the circumferential direction, the holding member communicates with the vent hole, is recessed in the optical axis direction, and extends in the circumferential direction. Provided with a plurality of notches connected to the inside of the concave groove provided at a plurality of locations in the circumferential direction on the inner diameter side, and the air rectifying means is provided at a position covering the front side of the concave groove and the notch. The lens barrel according to claim 4, wherein   The lens barrel according to any one of claims 1 to 5, wherein the air rectifying means includes a decorative ring for covering at least part of the front surface of the lens barrel.   The lens holding ring for holding the peripheral edge portion of the foremost lens on the lens holding member is provided, and a minute direction directed toward the front surface of the foremost lens is provided between the lens holding ring and the decorative ring. The lens barrel according to claim 6, wherein a gap is formed.   8. The lens barrel according to claim 1, wherein the foremost lens is movable in the optical axis direction, and a vent hole is opened in a lens holding member that holds the foremost lens. The lens barrel according to claim 8, wherein the foremost lens is a focus adjustment lens or a zoom adjustment lens.

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