JP2014032356A - Lens barrel and optical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve alignment accuracy of an optical member.SOLUTION: A lens barrel includes: an optical member; a first cylindrical member that has a cam pin protruding in a radial direction and is arranged coaxially with an optical axis of the optical member; and a second cylindrical member that has a cam groove engaging with the cam pin and is arranged coaxially with the first cylindrical member. When the first cylindrical member is relatively rotated around the optical axis to the second cylindrical member, the lens barrel drives the optical member in a direction in parallel with the optical axis, and the cam pin is formed so as to cave in from an annular face at which at least a part of the cam pin comes into contact with the cam groove and has a groove extending in a circumferential direction of the annular surface.

Description

  The present invention relates to a lens barrel and an optical apparatus.

There is a lens barrel in which a sub-pin and a sub-cam groove are provided to prevent the first group barrel from falling off (see Patent Document 1).
[Patent Document 1] JP 2011-039386 A

  When the sub cam groove is provided, the strength of the cam cylinder is lowered.

  In the first aspect of the present invention, the optical member, the first cylindrical member having a cam pin protruding in the radial direction and arranged coaxially with the optical axis of the optical member, and the cam groove engaging with the cam pin are provided. And a second cylindrical member arranged coaxially with the first cylindrical member, and when the first cylindrical member rotates relative to the second cylindrical member around the optical axis, the optical A lens barrel for driving a member in a direction parallel to the optical axis, wherein the cam pin is formed by being recessed from an annular surface at least partially in contact with the cam groove and extending in the circumferential direction of the annular surface A lens barrel is provided.

  In the second aspect of the present invention, an optical apparatus including the lens barrel is provided.

  The above summary of the present invention does not enumerate all necessary features of the present invention. Sub-combinations of these feature groups can also be an invention.

1 is a schematic cross-sectional view of a single-lens reflex camera 100. FIG. 2 is a schematic cross-sectional view of a lens unit 200. FIG. 3 is a schematic cross-sectional view orthogonal to the optical axis of the lens unit 200. FIG. It is a typical sectional view of the rear part of lens unit 200. It is a typical sectional view of the rear part of lens unit 200. It is a perspective view of the movable cam pin 292. It is sectional drawing of the movable cam pin 292. FIG. It is a typical sectional view of the rear part of lens unit 200.

  Hereinafter, the present invention will be described through embodiments of the invention. The following embodiments do not limit the invention according to the claims. Not all combinations of features described in the following embodiments are essential for the solution of the invention.

  FIG. 1 is a schematic cross-sectional view of a single-lens reflex camera 100 that is an example of an optical apparatus. The single-lens reflex camera 100 includes a lens unit 200 and a camera body 300.

  For the purpose of simplifying the description, in the following description, the object side with respect to the lens unit 200 attached to the camera body 300 is described as the front side or the front side of the single-lens reflex camera 100. Further, the side far from the object with respect to the lens unit 200 is referred to as a rear side or a back side in the single-lens reflex camera 100.

  The lens unit 200 includes a first lens group 210, a second lens group 220, a third lens group 230, a fourth lens group 240, a fifth lens group 250, and a sixth lens group arranged along the optical axis X. Has an optical system. The first lens group 210, the second lens group 220, the third lens group 230, the fourth lens group 240, the fifth lens group 250, and the sixth lens group have lens holding frames 212, 222, 232, 242, 252, respectively. 262 individually held.

  The illustrated lens unit 200 is in a retracted state in which the first lens group 210, the second lens group 220, the third lens group 230, the fourth lens group 240, the fifth lens group 250, and the sixth lens group 260 are close to each other. is there. Thereby, the length of the lens unit 200 in the optical axis X direction is shortened, and portability is improved. However, the lens unit 200 in the retracted state cannot be used as an optical device.

  The lens unit 200 includes a lens barrel including a fixed cylinder 201, a zoom ring 202, a rectilinear cylinder 203, a front cylinder 204, a cam cylinder 290, a guide cylinder 206, a front side moving frame 207 and a rear side moving frame 209. The fixed cylinder 201 has a lens side mount 208 at the rear end. The fixed cylinder 201 is coupled to the camera body 300 by coupling the lens side mount unit 208 to the body side mount unit 360 on the front surface of the camera body 300.

  The coupling between the lens side mount portion 208 and the body side mount portion 360 can be released. Therefore, the camera body 300 can be used in combination with another lens unit 200 having the lens side mount portion 208 that conforms to the standard.

  The zoom ring 202 is disposed on the outer peripheral surface of the fixed cylinder 201, and is rotated about the optical axis X of the optical system as a rotation axis by a user operation. The zoom ring 202 in the lens unit 200 is rotated by the user when the lens unit 200 is expanded to cancel the retracted state. The zoom ring 202 is also rotated by the user when the optical system of the lens unit 200 is scaled.

  In the lens unit 200, the lens holding frame 242 that holds the fourth lens group 240 is supported so as to be movable with respect to the front side moving frame 207. The lens holding frame 242 is driven by a feed screw assembly 270 fixed to the front side moving frame 207.

  The feed screw assembly 270 includes a stepping motor 272, a feed screw 274 and a frame 276. The frame 276 integrally supports the stepping motor 272 and the feed screw 274 and is fixed to the front side moving frame 207. The stepping motor 272 drives the feed screw 274 to rotate. The feed screw 274 engages with the lens holding frame 242 via the rack member 278.

  Thereby, the fourth lens group 240 held by the lens holding frame 242 can be moved. When the fourth lens group 240 moves, the focal position of the optical system of the lens unit 200 changes. Therefore, the lens unit 200 can be focused by electrically controlling the stepping motor 272 based on the signal from the camera body 300 side.

  The camera body 300 includes a mirror unit 370 disposed behind the body side mount portion 360. A focusing optical system 380 is disposed below the mirror unit 370. A focusing screen 352 is disposed above the mirror unit 370.

  A pentaprism 354 is disposed further above the focusing screen 352, and a finder optical system 356 is disposed behind the pentaprism 354. The rear end of the viewfinder optical system 356 is exposed as a viewfinder 350 on the back surface of the camera body 300.

  Behind the mirror unit 370, a shutter unit 310, a low-pass filter 332, an image sensor 330, a substrate 320, and a display unit 340 are sequentially arranged. A display unit 340 formed by a liquid crystal display panel or the like appears on the back surface of the camera body 300. A control unit 322, an image processing unit 324, and the like are mounted on the substrate 320.

  The mirror unit 370 includes a main mirror 371 and a sub mirror 374. The main mirror 371 is supported by a main mirror holding portion 372 that is pivotally supported by a main mirror rotating shaft 373.

  The sub mirror 374 is supported by a sub mirror holding portion 375 that is pivotally supported by a sub mirror rotating shaft 376. The sub mirror holding unit 375 rotates with respect to the main mirror holding unit 372. Therefore, when the main mirror holding part 372 rotates, the sub mirror holding part 375 is also displaced together with the main mirror holding part 372.

  When the front end of the main mirror holding portion 372 is lowered, the main mirror 371 is positioned obliquely on the incident light beam incident from the lens unit 200. When the main mirror holding part 372 moves up, the main mirror 371 retracts to a position avoiding the incident light beam.

  When the main mirror 371 is positioned on the incident light beam, the incident light beam incident through the lens unit 200 is reflected by the main mirror 371 and guided to the focusing screen 352. The focusing screen 352 is disposed at a position conjugate with the optical system of the lens unit 200, and visualizes an image formed by the optical system of the lens unit 200.

  The image on the focusing screen 352 is observed from the viewfinder 350 through the pentaprism 354 and the viewfinder optical system 356. Here, an erect image can be observed from the viewfinder 350 by observing the image through the pentaprism 354.

  The photometric sensor 390 is disposed above the finder optical system 356 and receives a part of the branched incident light beam. The photometric sensor 390 detects the subject brightness and causes the control unit 322 to calculate an exposure condition that is a part of the photographing condition.

  The main mirror 371 has a half mirror region that transmits a part of the incident light beam. The sub mirror 374 reflects a part of the incident light beam incident from the half mirror region toward the focusing optical system 380. The focusing optical system 380 guides a part of the incident incident light beam to the focus detection sensor 382. Thereby, the control unit 322 determines the target position of the lens that moves when the optical system of the lens unit 200 is focused.

  When the release button is half-pressed in the single-lens reflex camera 100 including the lens unit 200 and the camera body 300 as described above, the focus detection sensor 382 and the photometric sensor 390 are enabled, and a subject image can be taken under appropriate shooting conditions. It becomes a state.

  Next, when the release button is fully pressed, the main mirror 371 and the sub mirror 374 move to the retracted position, and the shutter unit 310 is opened. Thereby, the incident light beam incident from the lens unit 200 passes through the low-pass filter 332 and enters the image sensor 330. In this way, an image formed on the imaging surface of the imaging element 330 is captured by the optical system of the lens unit 200.

  FIG. 2 is a cross-sectional view of the lens unit 200. In FIG. 2, a cross section of the lens unit 200 that is scaled to the wide angle side is shown on the upper side of the optical axis X in the drawing. Further, in FIG. 2, a cross section of the lens unit 200 that is zoomed to the telephoto side is shown below the optical axis X in the drawing.

  In FIG. 2, the same elements as those in FIG. However, although FIG. 2 is common to FIG. 1 in that it is a cross section including the optical axis X, it shows a cross section different from FIG. Therefore, some of the common elements are drawn in a shape different from that in FIG.

  In the lens unit 200, the rectilinear cylinder 203 engages with the zoom ring 202 at the lead portion 281. Since the rectilinear cylinder 203 is suppressed from rotating with respect to the fixed cylinder 201, when the zoom ring 202 is rotated, a driving force that translates in the direction of the optical axis X is received from the zoom ring 202.

  The cam cylinder 290 engages in the vicinity of the rear end of the rectilinear cylinder 203 by a bayonet claw 286 disposed in the vicinity of the rear end of itself. Since the bayonet claw 286 engages with the bayonet groove extending in the circumferential direction on the inner surface of the rectilinear cylinder 203, the cam cylinder 290 can rotate around the optical axis X. However, when the rectilinear cylinder 203 translates in the optical axis X direction, the cam cylinder 290 also moves in the optical axis direction along with the rectilinear cylinder 203. In other words, the cam cylinder 290 and the rectilinear cylinder 203 are engaged only in the optical axis X direction.

  The cam cylinder 290 engages with a rectilinear groove 405 provided on the inner surface of the zoom ring 202 in parallel with the optical axis X through a connecting pin 285 fixed to the outer peripheral surface of the cam cylinder 290. Thereby, when the zoom ring 202 is rotated, the cam barrel 290 also rotates.

  As described above, when the zoom ring 202 is rotated, the rectilinear cylinder 203 translates in the optical axis X direction, and the cam cylinder 290 translates along with the rectilinear cylinder 203. Therefore, when the zoom ring 202 is rotated, the cam barrel 290 translates in the direction of the optical axis X while rotating around the optical axis X.

  The guide tube 206 is located inside the cam tube 290 and is coupled to the fixed tube 201 and fixed. Therefore, when the zoom ring 202 is rotated, the rectilinear cylinder 203 and the cam cylinder 290 also translate relative to the guide cylinder 206. Since the guide tube 206 extends toward the front end side of the lens unit 200 in the direction of the optical axis X, the guide tube 206 supports the cam tube 290 from the inner surface side and is associated with a key 287 provided at the rear end of the rectilinear tube 203. The rectilinear groove 288 is combined to restrict the rotation of the rectilinear cylinder 203.

  The front tube 204 supports the lens holding frame 212 of the first lens group 210 at the tip. Further, the front tube 204 is supported by being engaged with the rectilinear tube 203 and the cam tube 290 by a press-fitting cam pin 282 or the like. Therefore, when the rectilinear cylinder 203 and the cam cylinder 290 translate in the optical axis X direction, the leading cylinder 204 also translates in the optical axis X direction.

  Further, when the zoom ring 202 is rotated, the leading cylinder 204 is driven between the rectilinear cylinder 203 that translates without rotating and the cam cylinder 290 that translates while rotating, and the rectilinear cylinder 203 and the cam cylinder. Translate to 290 as well. As a result, the first lens group 210 held at the tip of the front tube 204 is largely extended forward from the fixed tube 201.

  The front-side moving frame 207 is disposed inside the cam cylinder 290 and the guide cylinder 206 and supports the lens holding frames 232 and 252 that hold the third lens group 230 and the fifth lens group 250 together. The rear moving frame 209 is disposed further inside the front moving frame 207 and supports the lens holding frame 262 that holds the sixth lens group 260.

  The front-side moving frame 207 and the rear-side moving frame 209 are engaged with the cam cylinder 290 and moved in the optical axis X direction when the zoom ring 202 is rotated. In the figure, a press-fit cam pin 264 that engages the rear moving frame 209 with the cam cylinder 290 is visible. The press-fitting cam pin 264 is fixed to the rear movement frame 209 by being press-fitted to the rear movement frame 209.

  The sixth lens group 260 further includes an additional lens group 261 arranged on the back side of the lens holding frame 262. The additional lens group 261 is held by an additional lens holding frame 263, and the additional lens holding frame 263 is fixed to the back surface of the lens holding frame 262.

  When the zoom ring 202 is rotated in the lens unit 200 as described above, the first lens group 210, the second lens group 220, the third lens group 230, the fifth lens group 250, and the sixth lens group 260 are fixed. Move relative to the tube 201. Thereby, the magnification of the optical system formed in the lens unit 200 changes. In addition, when the zoom ring 202 is rotated beyond the range of zooming of the lens unit 200, the lens unit 200 is contracted into a retracted state.

  FIG. 3 is a schematic cross-sectional view showing a cross section orthogonal to the optical axis X of the lens unit 200. Elements common to those in FIGS. 1 and 2 are denoted by the same reference numerals, and redundant description is omitted. In the lens unit 200, the zoom ring 202, the fixed cylinder 201, the front side moving frame 207, the cam cylinder 290, and the rear side moving frame 209 are arranged coaxially with respect to the optical axis X.

  In the lens unit 200, the connecting pin 285 fixed to the cam cylinder 290 protrudes outward in the radial direction and engages with a rectilinear groove 405 disposed on the inner surface of the zoom ring 202. As a result, the cam cylinder 290 rotates around the optical axis X with respect to the fixed cylinder 201 together with the zoom ring 202. The cam cylinder 290 has a movable cam pin 292 provided on the outer peripheral surface of the cam cylinder 290. The movable cam pin 292 protrudes toward the outer side in the radial direction of the lens unit 200 and engages with a cam groove 402 provided on the inner surface of the fixed cylinder 201.

  Furthermore, the cam cylinder 290 has a press-fitting cam pin 296 protruding from the outer peripheral surface in the vicinity of the tip, and a cam groove 294 provided on the inner peripheral surface. The press-fitting cam pin 296 is fixed to the cam cylinder 290 by press-fitting, protrudes outward in the radial direction, and engages with a cam groove 256 formed on the inner peripheral surface of the front-side moving frame 207. The cam groove 294 engages with a press-fit cam pin 264 fixed to the outer peripheral surface of the rear side moving frame 209.

  The rectilinear projection 259 of the front side moving frame 207 engages with the rectilinear groove 401 disposed on the inner surface of the fixed cylinder 201. The rectilinear protrusion 269 of the rear moving frame 209 engages with a rectilinear groove 404 disposed on the inner surface of the fixed cylinder 201. Thereby, the rotation of the front side moving frame 207 and the rear side moving frame 209 with respect to the fixed cylinder 201 is restricted.

  The movable cam pin 292, the press-fitting cam pins 264 and 296, the connecting pin 285 and the cam grooves 256, 294, and 402, the rectilinear protrusions 259 and 269, and the rectilinear grooves 401, 404, and 405 each have three circumferences of the lens unit 200. It is arranged at substantially equal intervals in the direction. As a result, the cam cylinder 290, the front side moving frame 207, the cam cylinder 290, and the rear side moving frame 209 are driven in a balanced manner in the circumferential direction of the lens unit 200 and are prevented from being inclined with respect to the optical axis X. .

  In the cam cylinder 290, the connecting pin 285 is disposed in the vicinity of the movable cam pin 292 in the circumferential direction of the lens unit 200. Thereby, when the connection pin 285 is driven, the inclination with respect to the optical axis X of the cam cylinder 290 caused by the displacement of the position with respect to the movable cam pin 292 can be suppressed. Similarly, the press-fitting cam pin 264 is preferably arranged in the vicinity of the rectilinear protrusion 269 in the circumferential direction of the lens unit 200.

  In the lens unit 200, each of the rectilinear grooves 401, 404, and 405 has a cross-sectional shape including side walls that are parallel to each other. In the cross section shown in the drawing, the widths of the lens unit 200 in the circumferential direction of the rectilinear protrusions 259 and 269 and the connecting pins that engage with the rectilinear grooves 401, 404, and 405 are constant.

  On the other hand, in the lens unit 200, the cam grooves 294, 256, 402 become wider in the circumferential direction as they approach the optical axis X, and the press-fitting cam pins 264, 296 or the movable cam pins 292 are inserted into the cam grooves 294, 256, 402. The cam surface is inclined with respect to the direction. The tabular cross-sectional shape of the cam grooves 294, 256, and 402 is such that the cam grooves 294, 256, and 402 having a bent cam profile are replaced with the cylindrical front side moving frame 207, the cam cylinder 290, and the rear side moving frame. It is derived from the shape of a mold that can be pulled out when molding into 209.

  Each of the press-fitting cam pins 264 and 296 and the movable cam pin 292 also contacts the cam surface of the cam groove 402 at a surface inclined with respect to the radial direction of the lens unit 200 following the inner surface shape of the cam grooves 294, 256 and 402. For this reason, each of the press-fitting cam pins 264 and 296 and the movable cam pin 292 has a truncated cone shape whose outer diameter decreases toward the tip.

  FIG. 4 is a schematic diagram showing a partial cross section of the lens unit 200 in the retracted state. The shape is simplified for the sake of simplicity.

  As shown in FIG. 3, the movable cam pin 292, the press-fit cam pins 264, 296, and the cam grooves 256, 294, 402 are arranged at different positions in the circumferential direction of the lens unit 200. Therefore, these elements do not appear simultaneously in a single cross section including the optical axis X of the lens unit 200. However, in FIG. 4, these elements are shown together for the purpose of showing the positional relationship between the movable cam pin 292 and the press-fitting cam pins 264 and 296 in the optical axis X direction.

  The rectilinear projecting portion 259 of the front side moving frame 207 and the rectilinear projecting portion 269 of the rear side moving frame 209 individually engage with the rectilinear grooves 401 and 404 that are independent from each other. Thereby, when the lens unit 200 is in the retracted state, the rear end portions of the front side moving frame 207 and the rear side moving frame 209 occupy the same position in the direction parallel to the optical axis X, and in the cross section including the optical axis X Can overlap. Therefore, the rear end of the front side moving frame 207 and the rear side moving frame 209 can be retracted until they abut against the rear surface of the fixed cylinder 201, and the length of the lens unit 200 in the optical axis X direction can be shortened.

  Further, in the lens unit 200, the lower end of the movable cam pin 292 in the figure is inserted into a housing portion 298 formed in the vicinity of the rear end of the cam cylinder 290. The accommodating portion 298 instructs the movable cam pin 292 to be slidable in the radial direction. In addition, the lens unit 200 includes a coil spring 291 that urges the movable cam pin 292 toward the outside in the radial direction inside the housing portion 298. As a result, the upper end of the movable cam pin 292 in the figure is pushed in the direction of fitting into the cam groove 402 of the fixed cylinder 201. Therefore, in the lens unit 200, rattling between the movable cam pin 292 and the cam groove 402 is prevented.

  FIG. 5 is a schematic diagram showing a cross section of the lens unit 200 in an expanded state in comparison with the cross section shown in FIG. Elements common to FIG. 4 are given the same reference numerals.

  When the zoom ring 202 is rotated in the lens unit 200, the cam cylinder 290 connected to the zoom ring 202 by the connection pin 285 also moves around the optical axis X relative to the fixed cylinder 201 together with the zoom ring 202. Rotate. The cam cylinder 290 accommodates the lower end side of the movable cam pin 292 in an accommodating portion 298 provided near the rear end of the cam cylinder 290. Since the upper end of the movable cam pin 292 is engaged with the cam groove 402 formed on the inner surface of the fixed cylinder 201, when the cam cylinder 290 rotates, the cam cylinder 290 is guided to the movable cam pin 292 guided by the cam groove 402. 290 moves in the optical axis X direction inside the fixed cylinder 201.

  When the cam cylinder 290 rotates around the optical axis X, the front-side moving frame 207 that engages with the cam groove 256 with respect to the press-fit cam pin 296 fixed to the cam cylinder 290 and rotating together with the cam cylinder 290 is also provided. Driving force is transmitted. Since the rotation of the front-side moving frame 207 is restricted by the rectilinear groove 401 with which the rectilinear protrusion 259 engages, when the driving force is transmitted from the cam groove 256, the front side moving frame 207 does not rotate and is parallel to the optical axis X Move to.

  Similarly, when the cam cylinder 290 rotates around the optical axis X, the cam groove 294 formed on the inner surface of the cam cylinder 290 also rotates with the cam cylinder 290. Therefore, the driving force is also transmitted to the rear moving frame 209 having the press-fitting cam pin 264 that engages with the cam groove 294. Since the rotation of the rear moving frame 209 is restricted by the rectilinear groove 404 with which the rectilinear protrusion 269 engages, when the driving force is transmitted to the press-fitting cam pin 264, the rear moving frame 209 does not rotate and is parallel to the optical axis X Move to.

  FIG. 6 is a perspective view showing the movable cam pin 292 alone. The movable cam pin 292 has a follower surface 293, a circumferential groove 295, a sliding surface 297, and a step 299 sequentially from the upper end in the drawing. The follower surface 293 forms an annular surface following the shape of the inner surface of the cam groove 402 and contacts the cam surface of the cam groove 402.

  The circumferential groove 295 is arranged in the middle of the follower surface 293 in the longitudinal direction of the movable cam pin 292, and circulates the follower surface 293 in a direction intersecting with the direction in which the movable cam pin 292 is inserted into and removed from the cam groove 402. It is formed. Thereby, the circumferential groove 295 extends in the circumferential direction of the annular follower surface 293. Further, the circumferential groove 295 has a shape recessed from the follower surface 293. Therefore, the follower surface 293 forms a continuous curved surface on the upper side and the lower side of the circumferential groove 295.

  The sliding surface 297 is formed following the lower end of the follower surface 293 in the figure, and has a cylindrical shape. The outer diameter of the sliding surface 297 is substantially equal to the inner diameter of the accommodating portion 298 of the cam cylinder 290. Therefore, when the sliding surface 297 of the movable cam pin 292 is inserted into the housing portion 298, the movable cam pin 292 slides in the radial direction without being inclined with respect to the peripheral surface of the cam cylinder 290.

  A step 299 is formed at the lower end of the sliding surface 297, and the outer diameter of the movable cam pin 292 is reduced. Thereby, the surface which receives the biasing force of the coil spring 291 is formed. Further, the coil spring 291 can be prevented from falling by inserting the small diameter portion at the lower end of the movable cam pin 292 into the coil spring 291.

  FIG. 7 is a cross-sectional view showing a cross section including the central axis C of the movable cam pin 292. In the movable cam pin 292, the circumferential groove 295 is formed so as to be recessed from the follower surface 293. Thereby, an inclined surface that forms an angle with respect to the follower surface 293 of the movable cam pin 292 is formed inside the circumferential groove 295. Such a movable cam pin 292 can be manufactured by cutting a metal material, for example.

  In the illustrated movable cam pin 292, the follower surface 293 and the inner surface of the circumferential groove 295 form an acute angle at least at the end on the distal end side of the movable cam pin 292 among the upper and lower ends of the circumferential groove 295. As a result, a sharp edge 289 is formed at the boundary between the circumferential groove 295 and the follower surface 293.

  FIG. 8 is a perspective view schematically showing a state in which an impact including a component parallel to the optical axis X is applied to the tip of the lens unit 200 in the expanded cylinder state as indicated by an arrow A in the drawing. . Elements common to FIG. 7 are given the same reference numerals.

  As already described, the movable cam pin 292 abuts the cam groove 402 on a surface having an inclination with respect to the optical axis X. Further, the press-fitting cam pins 264 and 296 also come into contact with the cam grooves 294 and 256 at a surface inclined with respect to the optical axis X.

  For this reason, when an impact in the optical axis X direction is applied to the tip of the lens unit 200, the movable cam pin 292 and the press-fit cam pins 264 and 296 have an action of coming out of the cam grooves 402, 294, and 256. Further, as shown by describing a straight two-dot chain line in the drawing, each of the fixed cylinder 201, the front side moving frame 207, the rear side moving frame 209, and the cam cylinder 290 is also deformed.

  However, when the movable cam pin 292 of the cam cylinder 290 is displaced in the direction of coming out of the cam groove 402, the circumferential groove 295 is formed in the circumferential direction of the movable cam pin 292. A ridge formed at the boundary with the inner surface enters the circumferential groove 295. As a result, the edge 289 of the circumferential groove 295 contacts the cam surface of the cam groove 402, and the movable cam pin 292 is caught by the cam groove 402, thereby preventing the movable cam pin 292 from falling off.

  As a result, dropping of the movable cam pin 292 is restricted, and the cam cylinder 290 is prevented from being stepped out of the fixed cylinder 201. As described above, the circumferential groove 295 has an arrangement and a shape to be hooked in contact with the fixed cylinder 201 including the cam groove 402 when each part of the lens unit 200 is deformed by an impact, and the movable cam pin 292 is caused by disturbance. Prevent step-out.

  The lens unit 200 has a structure in which the fixed cylinder 201 and the cam cylinder 290 are engaged by a movable cam pin 292 having a circumferential groove. However, even if a circumferential groove is provided on other cam pins such as a press-fitting cam pin 296 that engages the cam cylinder 290 and the front-side moving frame 207 and a press-fitting cam pin 264 that engages the cam cylinder 290 and the rear-side moving frame 209, The effect | action which suppresses step-out is obtained similarly to said example. Furthermore, a part or all of the press-fitting cam pins 264 and 296 may be replaced with the movable cam pins 292.

  In the above embodiment, the single-lens reflex camera 100 including the interchangeable lens unit 200 has been described as an example. However, the above-described structure can be applied even to a non-flex camera not including a quick return mirror. In addition to a camera in which the lens unit 200 and the camera body 300 are integrated, the above structure can be applied to a telescope, a surveying instrument, a microscope, and the like that include an optical member driven by a cam mechanism.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

100 single-lens reflex camera, 200 lens unit, 201 fixed cylinder, 202 zoom ring, 203 rectilinear cylinder, 204 front cylinder, 206 guide cylinder, 207 front side moving frame, 209 rear side moving frame, 208 lens side mount part, 210 1st Lens group, 212, 222, 232, 232, 242, 252, 262, 263 Lens holding frame, 220 Second lens group, 230 Third lens group, 240 Fourth lens group, 250 Fifth lens group, 256, 294, 402 Cam groove, 259, 269 Rectilinear projection, 260 Sixth lens group, 261 Additional lens group, 264, 282, 296 Press-fit cam pin, 270 Feed screw assembly, 272 Stepping motor, 274 Feed screw, 276 Frame, 278 Rack member 285 Connecting pin, 286 Bayonet claw, 287 key 288, 401, 404, 405 Straight groove, 289 edge, 290 cam cylinder, 291 coil spring, 292 movable cam pin, 293 follower surface, 295 circumferential groove, 297 sliding surface, 298 accommodating portion, 299 step, 300 camera body, 310 shutter unit, 320 substrate, 322 control unit, 324 image processing unit, 330 imaging device, 332 low-pass filter, 340 display unit, 350 finder, 352 focusing screen, 354 pentaprism, 356 finder optical system, 360 body side mount unit, 370 Mirror unit, 371 Main mirror, 372 Main mirror holding part, 373 Main mirror rotation axis, 374 Sub mirror, 375 Sub mirror holding part, 376 Sub mirror rotation axis, 380 Focusing optical system, 382 Focus detection sensor, 390 Photometric sensor

Claims (5)

An optical member;
A first cylindrical member having a cam pin protruding in the radial direction and arranged coaxially with the optical axis of the optical member;
A second cylindrical member having a cam groove engaging with the cam pin and arranged coaxially with the first cylindrical member;
A lens barrel that drives the optical member in a direction parallel to the optical axis when the first cylindrical member rotates relative to the second cylindrical member around the optical axis; ,
The cam pin is a lens barrel having a groove formed by being recessed from an annular surface at least partially in contact with the cam groove, and extending in a circumferential direction of the annular surface.   The lens barrel according to claim 1, further comprising a biasing member that biases the cam pin in a direction in which the cam pin is fitted into the cam groove.   2. The cross section including the central axis of the cam pin, wherein an inner surface of the groove and a surface of the cam pin in contact with the cam groove form an acute angle at an end near the tip of the cam pin among both ends of the groove. The lens barrel according to claim 2.   The lens barrel according to any one of claims 1 to 3, wherein the cam groove is in contact with the cam pin on a cam surface inclined with respect to a direction in which the cam pin is fitted into the cam groove.   An optical apparatus comprising the lens barrel according to any one of claims 1 to 4.

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