JP2014041317A - Lens barrel and imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress deterioration of optical performance occurred when a lens barrel is extended.SOLUTION: A lens barrel includes: a fixture barrel; an operation ring that is rotatively operated along a peripheral surface of the fixture barrel, and has one of a plurality of grooves and a plurality of protrusions arranged at an inner periphery thereof; a rectilinear advancing barrel that has a rotation restricted with respect to the fixture barrel, has the other of the plurality of grooves and the plurality of protrusions of the operation ring fit to the one thereof and rectilinearly advances with respect to the fixture barrel when the operation ring is rotatively operated; a rotary barrel that rotates integrally with the operation ring and rectilinearly advances integrally with the rectilinear advancing barrel; and a support part that has a rotation restricted to one of the rectilinear advancing barrel and the rotary barrel, rectilinearly advances to the rectilinear advancing barrel and the rotary barrel by receiving a driving force from the other of the rectilinear advancing barrel and the rotary barrel and supports an optical member.

Description

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

There is a zoom lens barrel that includes a cam barrel that is displaceably supported with respect to a base member, and a rectilinear barrel that is supported by the cam barrel and is further displaced with respect to the cam barrel (see Patent Document 1). .
[Patent Document 1] JP 2012-042578 A

  In some cases, the linear movement of the straight cylinder relative to the cam cylinder is superimposed on the vertical displacement of the cam cylinder relative to the base member, the optical axis of the optical member held by the linear movement cylinder is tilted, and the optical characteristics of the zoom lens barrel deteriorate.

  In the first aspect of the present invention, with respect to the fixed cylinder, the operation ring that is rotated along the peripheral surface of the fixed cylinder, and one of the plurality of grooves and the plurality of protrusions is arranged on the inner periphery, and the fixed cylinder A rectilinear cylinder that is restricted in rotation and has the other engaged with one of the plurality of grooves and the plurality of protrusions of the operating ring, and that moves straight with respect to the fixed cylinder when the operating ring is rotated; A rotation cylinder that rotates integrally with the rectilinear cylinder, and a rotation cylinder that is controlled to rotate by one of the rectilinear cylinder and the rotation cylinder. A lens barrel is provided that includes a support portion that goes straight with respect to the rotating barrel and supports the optical member.

  In the second aspect of the present invention, an imaging 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 camera system 100. FIG. 2 is a schematic cross-sectional view of a lens unit 200. FIG. 2 is a partial exploded perspective view of a lens unit 200. FIG. 3 is a plan view of an operation ring 202. FIG.

  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 the camera system 100. The camera system 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 camera system 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 camera system 100.

  The lens unit 200 has an optical system including a first lens group 210, a second lens group 220, a third lens group 230, and a fourth lens group 240 arranged along the optical axis X. The first lens group 210, the second lens group 220, the third lens group 230, and the fourth lens group 240 are individually held by individual lens holding frames 212, 222, 232, and 242, respectively.

  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, and the fourth lens group 240 are close to each other. Thereby, the length of the lens unit 200 in the optical axis X direction is shortened and the portability is improved, but the function as the optical device cannot be used.

  The lens unit 200 includes a lens barrel including a fixed cylinder 201, an operation ring 202, a rectilinear cylinder 203, a front cylinder 204, a cam cylinder 205, a guide cylinder 206, a first moving frame 207 and a second 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 operation 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 operation ring 202 is engaged with the rectilinear cylinder 203 and the cam cylinder 205 by a cam groove, a straight groove, or the like formed on the inner surface. The rectilinear cylinder 203 moves in the optical axis X direction with respect to the fixed cylinder 201. In addition, the cam cylinder 205 moves in the optical axis X direction along with the rectilinear cylinder 203 while rotating together with the operation ring 202.

  The guide cylinder 206 located inside the cam cylinder 205 is coupled to the fixed cylinder 201 and does not move relative to the fixed cylinder 201. Therefore, the cam cylinder 205 moves in the optical axis X direction also with respect to the guide cylinder 206.

  The front tube 204 is engaged with and supported by the straight tube 203 and the cam tube 205. Accordingly, the leading cylinder 204 moves in the optical axis X direction in accordance with the movement of the rectilinear cylinder 203 and the cam cylinder 205 with respect to the fixed cylinder 201.

  Further, the leading cylinder 204 is driven between the rectilinear cylinder 203 that moves in the optical axis X direction without rotating and the cam cylinder 205 that moves in the optical axis X direction while rotating, and the rectilinear cylinder 203 and the cam cylinder are driven. Also move to 205. Since the front tube 204 supports the lens holding frame 212 that holds the first lens group 210 at the tip, the first lens group 210 also moves as the front tube 204 moves.

  The first moving frame 207 and the second moving frame 209 have cam pins 283 and 284 that engage with cam grooves formed in the cam cylinder 205, respectively. It moves individually in the direction of the optical axis X. Accordingly, the first moving frame 207 moves the lens holding frame 222 holding the second lens group 220 in the optical axis light direction. The second moving frame 209 is connected to a lens holding frame 242 that holds the fourth lens group 240 and moves the fourth lens group 240 in the optical axis X direction.

  Further, the lens holding frame 232 that holds the third lens group 230 is driven by a feed screw assembly 270 that is fixed to the lens holding frame 242 that holds the fourth lens group 240, so that the lens holding frame 242 is not moved. And is further movably supported. 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 lens holding frame 242. The stepping motor 272 drives the feed screw 274 to rotate. The feed screw 274 engages with the lens holding frame 232 via the rack member 278.

  Thereby, the third lens group 230 held by the lens holding frame 232 can be moved. When the third lens group 230 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 pressed halfway in the camera system 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 captured under appropriate shooting conditions. become. 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.

  FIG. 2 is a partial cross-sectional view showing another state of the lens unit 200, and shows a cross section of the lens unit 200 that has been scaled to the wide-angle side on the upper side in the drawing with respect to the optical axis X. In addition, 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 reference numerals are assigned to 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, a cross section different from FIG. 1 is shown. Even if it is an element common to FIG. May appear in different shapes.

  In the lens unit 200, the rectilinear cylinder 203 is engaged with the operation ring 202 in the lead portion 281. Since the rectilinear cylinder 203 is restrained from rotating with respect to the fixed cylinder 201, when the operation ring 202 is rotated, the driving cylinder 202 receives a driving force that moves in the optical axis X direction from the operation ring 202.

  The cam cylinder 205 is engaged 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 the cam cylinder 205. The bayonet claw 286 engages with a bayonet groove extending in the circumferential direction on the inner surface of the rectilinear cylinder 203, so that the cam cylinder 205 can rotate around the optical axis X. However, when the rectilinear cylinder 203 moves in the optical axis X direction, the cam cylinder 205 also moves in the optical axis direction along with the rectilinear cylinder 203. In other words, the cam cylinder 205 and the rectilinear cylinder 203 are engaged only in the optical axis X direction.

  The cam cylinder 205 is engaged with a groove provided in the inner surface of the operation ring 202 in parallel with the optical axis X through a connecting pin 285 fixed to the outer peripheral surface of the cam cylinder 205. Thereby, when the operation ring 202 is rotated, the cam cylinder 205 is also rotated.

  As described above, when the operation ring 202 is rotated, the rectilinear cylinder 203 moves in the direction of the optical axis X, and the cam cylinder 205 moves along with the rectilinear cylinder 203. Therefore, when the operation ring 202 is rotated, the cam cylinder 205 moves in the optical axis X direction while rotating around the optical axis X.

  The guide tube 206 is positioned inside the cam tube 205 and is coupled to the fixed tube 201 and fixed. Therefore, when the operation ring 202 is rotated, the rectilinear cylinder 203 and the cam cylinder 205 also move 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 205 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 joined to suppress 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 from both sides by engaging with the straight tube 203 and the cam tube 205 by a cam pin 282 or the like. Therefore, when the rectilinear cylinder 203 and the cam cylinder 205 move in the optical axis X direction, the leading cylinder 204 also moves in the optical axis X direction accordingly.

  Further, when the operation ring 202 is rotated, the front tube 204 is moved between the rectilinear tube 203 that moves in the optical axis X direction without rotating and the cam tube 205 that moves in the optical axis X direction while rotating. When driven, the linear movement cylinder 203 and the cam cylinder 205 are also moved in the optical axis X direction. 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.

  As described above, when the operation ring 202 is rotated, the first lens group 210, the second lens group 220, the third lens group 230, and the fourth lens group 240 individually move with respect to the fixed barrel 201. . Thereby, the magnification of the optical system formed in the lens unit 200 changes according to the rotation amount of the operation ring 202. Further, when the operation ring 202 is rotated beyond the zooming range of the lens unit 200, the lens unit 200 is in a retracted state.

  FIG. 3 is an exploded perspective view showing a part of the lens unit 200. FIG. 3 shows a fixed cylinder 201, a guide cylinder 206, an operation ring 202, a rectilinear cylinder 203, and a cam cylinder 205. Elements common to those in FIGS. 1 and 2 are denoted by the same reference numerals, and redundant description is omitted.

  The guide tube 206 has a plurality of positioning portions 295 that protrude outward in the radial direction. As a result, the guide tube 206 is positioned at a predetermined position inside the fixed tube 201 and is fixed to the fixed tube 201. The guide cylinder 206 is fixed to the fixed cylinder 201 by, for example, screwing.

  A plurality of lead grooves 294 are arranged on the outer peripheral surface of the guide tube 206. The lead groove 294 engages with a lead portion provided on the inner surface of the cam cylinder 205. Accordingly, when the operation ring 202 is rotated and the cam cylinder 205 moves in the direction of the optical axis X while rotating with respect to the fixed cylinder 201, the movement path of the cam cylinder 205 is guided.

  Further, a rectilinear groove 288 extending in the optical axis X direction is disposed on the outer peripheral surface of the guide tube 206. The rectilinear groove 288 engages with a key 287 provided at the rear end of the rectilinear cylinder 203 and restricts rotation while allowing the rectilinear cylinder 203 to move in the optical axis X direction.

  The cam cylinder 205 is fitted on the outside of the guide cylinder 206. The cam cylinder 205 has a plurality of bayonet claws 286 protruding in the radial direction in the vicinity of the rear end of the outer peripheral surface of the cam cylinder 205. The bayonet claw 286 engages with a bayonet groove arranged in the circumferential direction on the inner surface near the rear end of the rectilinear cylinder 203. Thereby, the cam cylinder 205 is connected to the rectilinear cylinder 203 in the optical axis X direction while being allowed to rotate with respect to the rectilinear cylinder 203.

  The cam cylinder 205 has a large number of cam grooves 291 on the outer peripheral surface. The cam groove 291 engages with the cam pin 282 of the front tube 204 and gives a driving force in the direction of the optical axis X to the front tube 204 whose rotation is restricted by the rectilinear tube 203.

  The rectilinear cylinder 203 has a bayonet groove on the inner surface that engages with the bayonet claw 286 of the cam cylinder 205. The bayonet groove extends in the circumferential direction on the inner surface of the rectilinear cylinder 203 and is partially cut out in the optical axis X direction. As a result, when the rectilinear cylinder 203 is mounted outside the cam cylinder 205, the bayonet claw 286 of the cam cylinder 205 can be fitted in the bayonet groove in the optical axis X direction.

  The rectilinear cylinder 203 has a plurality of lead portions 292 in the vicinity of the rear end of the outer peripheral surface. The lead portion 292 protrudes outward in the radial direction of the rectilinear cylinder 203. When extended forward, the outer peripheral surface of the rectilinear cylinder 203 is exposed toward the outside of the lens unit 200. Therefore, the surface and front end of the rectilinear cylinder 203 are finished flat without providing grooves, protrusions, notches, and the like.

  The operation ring 202 is attached to the outermost periphery of the lens unit 200 and rotates with respect to the fixed cylinder 201. A plurality of spiral lead grooves 293 are arranged on the inner surface of the operation ring 202. When the operation ring 202 is attached to the lens unit 200, the lead groove 293 engages with the lead portion 292 of the rectilinear cylinder 203.

  In the lens unit 200 including the fixed cylinder 201, the operation ring 202, the rectilinear cylinder 203, the cam cylinder 205, and the guide cylinder 206 as described above, the lead portion 292 of the rectilinear cylinder 203 is disposed near the rear end of the rectilinear cylinder 203. Has been. Further, the lead groove 293 extends to the inner surface front end of the operation ring 202. Therefore, the rectilinear cylinder 203 can be extended to a length close to its entire length, and the magnification of the lens unit 200 can be increased.

  In addition, since a plurality of lead portions 292 that engage with the lead grooves 293 are provided on the circumference of the rectilinear cylinder 203, the positioning of the rectilinear cylinder 203 by the operation ring 202 is stabilized. Further, the rectilinear cylinder 203 engages with the guide cylinder 206 fixed to the fixed cylinder 201 at a plurality of keys 287 provided at the rear end separated from the position of the lead portion 292 in the optical axis X direction. Therefore, the tilt of the rectilinear cylinder 203 with respect to the optical axis X is prevented from being shaken.

  Furthermore, since the inclination of the rectilinear cylinder 203 with respect to the fixed cylinder 201 is stabilized, a change in the inclination of the front cylinder 204 supported by the rectilinear cylinder 203 with respect to the optical axis is also suppressed. Therefore, even if the straight cylinder 203 and the front cylinder 204 are extended in two stages, the optical performance of the lens unit 200 is unlikely to change. As a result, a high-magnification variable power lens unit that stably exhibits high optical performance can be provided. In other words, it is possible to form the lens unit 200 with higher magnification while maintaining the optical performance.

  FIG. 4 is a schematic side view of the operation ring 202, and the right side in the drawing corresponds to the rear end side of the lens unit 200. Elements that are the same as those in FIGS. 1, 2, and 3 are given the same reference numerals, and redundant descriptions are omitted.

  A lead groove 293 and a drive groove 296 are disposed on the inner surface of the operation ring 202. The lead groove 293 and the drive groove 296 are both formed in a spiral shape, but the inclination with respect to the optical axis X is different from each other.

  Here, the lead portion 292 of the rectilinear cylinder 203 is engaged with the lead groove 293. The lead portion 292 has a parallelogram-shaped planar shape following the side wall of the lead groove 293. Therefore, the lead portion 292 and the lead groove 293 are engaged by contact between surfaces, not by point contact or line contact.

  In the operation ring 202, the connecting pin 285 is engaged with the driving groove 296. The connection pin 285 also has a planar shape including a pair of parallel surfaces when viewed in the radial direction of the lens unit 200. Therefore, the drive groove 296 and the connecting pin 285 are also engaged not by point contact or line contact but by contact between surfaces.

  In the inner surface of the operation ring 202 as described above, the length of the surface in contact with the lead groove 293 in the lead portion 292 is longer than the width of the drive groove 296 in the extending direction of the lead groove 293. In the extending direction of the drive groove 296, the length of the surface of the connecting pin 285 that contacts the drive groove 296 is longer than the width of the lead groove 293. As a result, the engagement of the connecting pin 285 with the drive groove 296 is maintained even at the intersection of the drive groove 296 and the lead groove 293. Further, the engagement of the lead portion 292 with the lead groove 293 is maintained at the intersection of the drive groove 296 and the lead groove 293.

  The lens interchangeable single-lens reflex camera including the interchangeable lens unit 200 has been described above as an example, but the above-described structure can be applied even to a lens interchangeable imaging apparatus that does not include a quick return mirror. Furthermore, in addition to a camera in which the lens unit 200 and the camera body 300 are integrally formed, the above structure can be applied to a telescope, a surveying instrument, a microscope, and the like that include an optical member that is driven by a rack mechanism 400.

  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.

DESCRIPTION OF SYMBOLS 100 Camera system 200 Lens unit 201 Fixed cylinder 202 Operation ring 203 Straight cylinder 204 Lead cylinder 205 Cam cylinder 206 Guide cylinder 207 1st moving frame 208 Lens side mount part 209 2nd moving frame 210 First lens group, 212, 222, 232, 232, 242 Lens holding frame, 220 Second lens group, 230 Third lens group, 240 Fourth lens group, 270 Feed screw assembly, 272 Stepping motor, 274 Feed screw 276 frame, 278 rack member, 281, 292 lead part, 282, 283, 284 cam pin, 285 connecting pin, 286 bayonet claw, 287 key, 288 rectilinear groove, 291 cam groove, 293, 294 lead groove, 295 positioning part, 296 Drive groove, 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 holder, 373 Main mirror rotation axis, 374 Sub mirror, 375 Sub mirror holder, 376 Sub mirror rotation axis, 380 Focusing optical system, 382 Focus detection sensor, 390 Photometric sensor

Claims (5)

A fixed cylinder;
An operation ring that is rotated along the peripheral surface of the fixed cylinder, and one of a plurality of grooves and a plurality of protrusions is arranged on the inner periphery,
Rotation is restricted with respect to the fixed cylinder, and the other is engaged with the one of the plurality of grooves and the plurality of protrusions of the operation ring, and the fixing is performed when the operation ring is rotated. A rectilinear cylinder that goes straight relative to the cylinder;
A rotating cylinder that rotates integrally with the operation ring and that moves integrally with the rectilinear cylinder;
A support portion that is restricted in rotation by one of the rectilinear cylinder and the rotating cylinder, receives a driving force from the other of the rectilinear cylinder and the rotating cylinder, moves straight to the rectilinear cylinder and the rotating cylinder, and supports an optical member A lens barrel. The rectilinear cylinder is fixed by the rectilinear groove provided in one of the fixed cylinder and the rectilinear cylinder, and the engaging protrusion provided in the other of the fixed cylinder and the rectilinear cylinder and engaged with the rectilinear groove. The rotation with respect to the cylinder is restricted,
2. The lens barrel according to claim 1, wherein a position where the rectilinear groove and the engagement protrusion are in contact with each other is separated from a position where the plurality of grooves and the plurality of protrusions are in contact with each other in the optical axis direction of the optical member.   3. The lens barrel according to claim 1, wherein each of the plurality of grooves and the plurality of protrusions is in contact with each other in parallel surfaces.   4. The method according to claim 1, wherein the plurality of protrusions are arranged at positions where the plurality of grooves and the plurality of protrusions engage with each other when the overlap between the rectilinear cylinder and the fixed cylinder is the smallest. The lens barrel according to claim 1.   The imaging device provided with the lens barrel as described in any one of Claim 1- Claim 4.

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