JP2014085484A - Lens barrel, and imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase a total rotation amount of a zoom ring.SOLUTION: A lens barrel includes: a fixed guide tube that has one of a spiral first convex reed and a spiral first concave reed which engage with each other; an operation ring that has one of a spiral second convex reed and a spiral second concave reed which engage with each other, and rotates with respect to the guide tube in accordance with an operation of a user; and a drive tube that has the other of the first convex reed and the first concave reed and has the other of the second convex reed and the second concave reed, and when a rotational movement is transmitted from the operation ring, drives an optical member by the rotational movement smaller in a rotation amount than the rotation amount of the operation ring.

Description

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

There is a lens device that includes a cam barrel that rotates when a zoom ring is operated, and has a structure in which the lens is moved by the cam barrel (see Patent Document 1).
[Patent Document 1] Japanese Patent Application Laid-Open No. 2002-107611

  If the total rotation amount of the zoom ring is increased for the purpose of improving the detection accuracy of the rotation amount of the zoom ring, the layout is restricted when a plurality of cam grooves are provided in the circumferential direction in one cam cylinder.

  In the first aspect of the present invention, a fixed guide cylinder having one of a spiral first convex lead and a first concave lead engaging each other, a spiral second convex lead engaging with each other, and a first An operation ring having one of two concave leads and rotating with respect to the guide tube in accordance with a user operation, the other of the first convex lead and the first concave lead, and the other of the second convex lead and the second concave lead When a rotational motion is transmitted from the operating ring, a lens barrel is provided that includes a drive barrel that drives the optical member by a rotational motion that is less than the rotational amount of the operating ring.

  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. It is a perspective view of the guide cylinder 206 alone. It is a perspective view which shows the cam cylinder 205 independently. It is a top view of the engaging member 285. It is a perspective view which shows the front tube 204 independently. FIG. 6 is a development view showing a layout on the outer peripheral surface of the zoom ring 202. FIG. 6 is a development view showing a layout on an outer peripheral surface of a straight cylinder 203. FIG. 6 is a development view showing a layout on an outer peripheral surface of a guide cylinder 206. FIG. 5 is a development view showing a layout on an outer peripheral surface of a cam cylinder 205.

  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 Z. 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 Z direction is shortened and the portability is improved, but the function as the optical device cannot be used.

  The lens unit 200 has a lens barrel including a fixed cylinder 201, a zoom 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 lens unit 200 can release the coupling between the lens side mount unit 208 and the body side mount unit 360 by rotating the lens unit 200 with respect to the camera body 300. 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 lens unit 200, and rotates around the optical axis Z of the optical system as a rotation axis by a user operation. The zoom ring 202 is engaged with the rectilinear cylinder 203 and the cam cylinder 205 by a lead groove or the like formed on the inner surface. The rectilinear cylinder 203 moves in the optical axis Z direction with respect to the fixed cylinder 201.

  The cam cylinder 205 rotates along with the zoom ring 202 and moves in the direction of the optical axis Z along with the rectilinear cylinder 203. A guide cylinder 206 located inside the cam cylinder 205 is fixed to the fixed cylinder 201. Therefore, the cam cylinder 205 also moves in the optical axis Z direction 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. As a result, the leading cylinder 204 moves in the optical axis Z direction in accordance with the movement of the rectilinear cylinder 203 and the cam cylinder 205 relative to the fixed cylinder 201.

  Further, the leading cylinder 204 is driven between a rectilinear cylinder 203 that moves in the optical axis Z direction without rotating and a cam cylinder 205 that moves in the optical axis Z 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 optical axis Z direction. 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 indirectly or directly connects the lens holding frames 232 and 242 that hold the third lens group 230 and the fourth lens group 240, so that the third lens group 230 and the fourth lens group are connected. 240 is moved in the optical axis Z direction.

  Furthermore, 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, and further to the lens holding frame 242. It is supported movably. 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 relative to the lens holding frame 242 holding the fourth lens group 240. When the third lens group 230 moves in the lens unit 200, 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 is scaled to the wide-angle side on the upper side in the drawing with respect to the optical axis Z. 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 Z 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 Z, a cross-section different from FIG. 1 is shown. May appear in different shapes.

  In the lens unit 200, the rectilinear cylinder 203 is engaged with the zoom ring 202 at the lead piece 292. Since the rectilinear cylinder 203 is restricted from rotating with respect to the guide cylinder 206, when the zoom ring 202 is rotated, the driving force moving in the optical axis Z direction is received from the zoom 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 the 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 Z. However, when the rectilinear cylinder 203 moves in the optical axis Z 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 Z direction.

  The cam cylinder 205 is engaged with a groove provided on the inner surface of the zoom ring 202 in parallel with the optical axis Z through an engagement member 285 fixed to the outer peripheral surface of the cam cylinder 205. Thereby, when the zoom ring 202 is rotated, the cam cylinder 205 also rotates.

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

  Further, when the zoom 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 Z, the guide tube 206 supports the cam tube 205 from the inner surface side, and includes a rectilinear key 255 provided at the rear end of the rectilinear tube 203. The rotation of the rectilinear cylinder 203 is suppressed by the engaging rectilinear groove 288.

  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 engaged with and supported by the rectilinear tube 203 and the cam tube 205 by a cam pin 281 and the like. Therefore, when the rectilinear cylinder 203 and the cam cylinder 205 move in the optical axis Z direction, the leading cylinder 204 moves accordingly in the optical axis Z direction.

  Further, when the zoom ring 202 is rotated, the front tube 204 is moved between the rectilinear tube 203 that moves in the optical axis Z direction without rotating and the cam tube 205 that moves in the optical axis Z direction while rotating. When driven, the linearly moving cylinder 203 and the cam cylinder 205 are also moved in the optical axis Z 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 zoom 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 cylinder 201. . Thereby, the magnification of the optical system formed in the lens unit 200 changes according to the rotation amount of the zoom ring 202. Further, when the zoom ring 202 is rotated beyond the range of zooming of the lens unit 200, the lens unit 200 is in a shortened retracted state.

  FIG. 3 is an exploded perspective view of a part of the lens unit 200. FIG. 3 shows a zoom ring 202, a flexible substrate 251, a fixed cylinder 201, a guide cylinder 206, a rectilinear cylinder 203, and a cam cylinder 205.

  The zoom 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 concave leads 293 are provided on the inner surface of the zoom ring 202 as an example of a third concave lead. When the zoom ring 202 is attached to the lens unit 200, the concave lead 293 engages with a lead piece 292 of a rectilinear cylinder 203 as an example of a third convex lead.

  A brush 252 is attached to the zoom ring 202. The brush 252 is biased toward the inside in the radial direction of the lens unit 200 through an opening provided in the zoom ring 202. Thus, the brush 252 has elasticity and forms an electrical contact that rotates with the zoom ring 202.

  The flexible substrate 251 is attached along the outer peripheral surface of the fixed cylinder 201. A plurality of contacts are provided on the surface of the flexible substrate 251 along the circumferential direction of the fixed cylinder 201. The brush 252 is electrically connected to one of the contacts on the flexible substrate 251 as the zoom ring 202 rotates, and electrically detects the amount of rotation of the zoom ring 202.

  The fixed cylinder 201 is coupled to the lens side mount unit 208. Therefore, when the lens unit 200 is attached to the camera body 300, the fixed cylinder 201 is also fixed to the camera body 300 and becomes a reference for the operation of the lens unit 200.

  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. Thereby, the guide tube 206 is integrated with the fixed tube 201.

  FIG. 4 is a perspective view showing the guide tube 206 in an enlarged manner, and shows a state in which the guide tube 206 is looked up slightly from the rear. On the outer peripheral surface of the guide tube 206, a plurality of concave leads 294 having a concave cross section formed in a spiral shape in pairs of two are arranged as an example of the first concave lead. These concave leads 294 engage with convex leads 253 provided as an example of first convex leads on the inner surface of the cam cylinder 205. Thereby, when the cam cylinder 205 moves in the direction of the optical axis Z while rotating with respect to the guide cylinder 206, the movement path of the cam cylinder 205 is guided.

  Further, a rectilinear groove 288 extending in the optical axis Z direction is disposed on the outer peripheral surface of the guide tube 206. The rectilinear groove 288 engages with a rectilinear key 255 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 Z direction.

  Referring to FIG. 3 again, the rectilinear cylinder 203 has a bayonet groove that engages with the bayonet claw 286 of the cam cylinder 205 on the inner surface. The bayonet groove extends in the circumferential direction on the inner surface of the rectilinear cylinder 203, and a part thereof is notched in the optical axis Z 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 Z direction.

  The rectilinear cylinder 203 has a rectilinear groove 297 provided in the optical axis Z direction. The rectilinear groove 297 engages with a part of the front tube 204 and restricts the rotation of the front tube 204 around the optical axis Z.

  Further, the rectilinear cylinder 203 has a plurality of lead pieces 292 in the vicinity of the rear end of the outer peripheral surface. The lead piece 292 protrudes outward in the radial direction of the rectilinear cylinder 203. Note that when extended forward, the front end side of 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.

  In the assembled lens unit 200, a cam cylinder 205 is disposed outside the guide cylinder 206 in the radial direction and inside the rectilinear cylinder 203. A plurality of bayonet claws 286 projecting outward in the radial direction are provided 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. As a result, the cam cylinder 205 is allowed to rotate with respect to the rectilinear cylinder 203 and moves along with the rectilinear cylinder 203 in the optical axis Z direction.

  FIG. 5 is an enlarged perspective view showing the cam cylinder 205 alone, and shows a state where the cam cylinder 205 is looked up slightly from the rear. A plurality of cam groove groups in which a pair of drive cam grooves 291 and a single impact cam groove 299 are combined are arranged on the outer peripheral surface of the cam cylinder 205. In each cam groove group, the pair of drive cam grooves 291 are disposed with a single impact cam groove 299 interposed therebetween.

  One end of the drive cam groove 291 has a groove end opening 290 connected to the end face in the optical axis direction of the cam cylinder 205. In a set of cam grooves formed by a pair of drive cam grooves 291 and one shock-resistant cam groove 299, one drive cam groove 291 and shock-resistant cam groove 299 share the groove end opening 290. Thereby, the area of the thin part of the cam cylinder 205 can be reduced, and the strength of the cam cylinder 205 can be improved.

  A plurality of convex leads 253 and drive cam grooves 254 are disposed on the inner peripheral surface of the cam cylinder 205. In the lens unit 200, the convex lead 253 engages with the concave lead 294 of the guide tube 206 as described above.

  The drive cam groove 254 engages with a cam pin provided integrally with the optical member. More specifically, a cam pin provided on the lens holding frame 222 holding the second lens group 220 and a cam pin provided on the second moving frame 209 coupled to the lens holding frame 242 holding the fourth lens group are provided. , Engages with the drive cam groove 254.

  Further, an engaging member 285 is screwed to the outer peripheral surface of the cam cylinder 205. The engaging member 285 protrudes from the cam cylinder 205 toward the radially outer side of the cam cylinder 205. The engaging member 285 engages with the inner surface of the zoom ring 202.

  FIG. 5 shows a state in which the engaging member 285 is attached to the cam cylinder 205. However, the engaging member 285 attached to the cam cylinder 205 protrudes further outward from the outer peripheral surface of the cam cylinder 205. For this reason, it cannot be inserted inside the rectilinear cylinder 203 or the like with the engaging member 285 attached. Therefore, when the lens unit 200 is assembled, the engaging member 285 is attached to the cam cylinder 205 after the cam cylinder 205 is inserted inside the rectilinear cylinder 203 or the like.

  FIG. 6 is a plan view showing the engagement member 285 alone. The engaging member 285 has a mounting portion 256 and a lead portion 257.

  The attachment portion 256 has a screw insertion hole 261 and a rotation stop hole 262 on a surface having a shape following the outer peripheral surface of the cam cylinder 205. The screw insertion hole 261 allows a set screw to be inserted when the engaging member 285 is attached to the outer peripheral surface of the cam cylinder 205.

The anti-rotation hole 262 is fitted with a protrusion provided on the outer peripheral surface of the cam cylinder 205 to prevent the engagement member 285 from rotating when a rotational moment acts on the engagement member 285. With these structures, the engaging member 285 can be screwed together with the attachment portion 256 in close contact with the outer peripheral surface of the cam cylinder 205, so that the engaging member 285 and the cam cylinder 205 can be integrated.
The lead portion 257 is formed integrally with the mounting portion 256 at one end and has a shape that fits into a lead groove provided in the zoom ring 202. A lead groove with which the lead portion 257 engages is formed in the zoom ring 202 in a spiral shape. Therefore, the lead part 257 engaged therewith has a parallelogram planar shape.

Further, the other end of the lead portion 257 protrudes outward from the attachment portion 256. Therefore, when the engaging member 285 is attached to the cam cylinder 205, the leading end portion of the lead portion 257 is separated from the outer peripheral surface of the cam cylinder 205. Thus, even while the screw insertion holes 261 provided in the mounting portion 256, has sufficient length B ₁ of the lead portion 257.

  Referring again to FIG. 3, in the assembled lens unit 200, the rear end of the front tube 204 is sandwiched between the cam tube 205 and the rectilinear tube 203 on the radially outer side. The front tube 204 supports the lens holding frame 212 of the first lens group 210 at the tip.

  FIG. 7 is a perspective view showing the front tube 204 alone, and shows a state where the front tube 204 is looked up slightly from the rear. The front tube 204 has three rectilinear pieces 282 near the rear end of the outer peripheral surface.

  The three rectilinear pieces 282 are arranged at equal intervals in the circumferential direction of the front tube 204. In the lens unit 200, the rectilinear piece 282 engages with a rectilinear groove 297 formed on the inner surface of the rectilinear cylinder 203. Thereby, the rotation of the front tube 204 with respect to the rectilinear tube 203 is restricted. Since the rectilinear cylinder 203 is also restricted from rotating relative to the guide cylinder 206, the leading cylinder 204 is also restricted from rotating relative to the guide cylinder 206.

  Further, the front tube 204 has a plurality of cam pins 281 and impact resistant pieces 289 in the vicinity of the rear end of the inner surface. The three impact resistant pieces 289 are arranged at equal intervals in the circumferential direction of the front tube 204. Each of the impact resistant pieces 289 has an upstanding peripheral surface that is nearly parallel to the radial direction of the front tube 204. Further, the peripheral surface of each of the impact resistant pieces 289 includes a pair of planes orthogonal to the optical axis Z of the lens unit.

  When the lens unit 200 is assembled, the cam pin 281 and the impact resistant piece 289 of the front tube 204 are inserted into the drive cam groove 291 and the impact resistant cam groove 299 through the groove end opening 290 of the cam tube 205. The cam pin 281 inserted into the drive cam groove 291 of the cam cylinder 205 is always in contact with the drive cam groove 291 to position and drive the leading cylinder 204.

  The impact-resistant piece 289 inserted into the impact-resistant cam groove 299 of the cam cylinder 205 is separated from the cam surface of the impact-resistant cam groove 299 when no mechanical load is applied to the leading cylinder 204. However, when the tip of the front tube 204 is pushed, or when an impact is applied to the lens unit 200, the impact is dispersed by coming into contact with the impact resistant cam groove 299. This protects the drive cam groove 291 and prevents the cam pin 281 from stepping out.

  As described above, in the lens unit 200, the flexible substrate 251 is used as a scale, and the amount of rotation operation of the zoom ring 202 is measured by measuring the relative movement amount of the zoom ring 202 with respect to the fixed cylinder 201 using an encoder using a brush 252. Can be detected. Thereby, the control unit 322 of the camera system 100 can detect the focal length set in the lens unit 200.

  Here, the detection accuracy of the operation amount can be improved by increasing the rotation amount of the zoom ring 202 by the user's operation. However, when the amount of rotation of the cam cylinder 205 that rotates in response to an operation on the zoom ring 202 increases, the respective circumferential dimensions of the convex lead 253, the drive cam groove 291 and the impact cam groove 299 formed on the cam cylinder 205 are increased. Becomes longer. For this reason, the number and length of the drive cam grooves 254 and the like that can be arranged in the cam cylinder 205 are limited.

  However, in the lens unit 200, by reducing the rotation amount of the cam cylinder 205 from the rotation amount by the rotation operation of the zoom ring 202, the accuracy of detecting the rotation amount of the zoom ring 202 is improved and the cam cylinder 205 has a large amount of rotation. A drive cam groove 254 is disposed.

  FIG. 8 is a development view showing a layout on the outer peripheral surface of the zoom ring 202. The upper side in the figure corresponds to the front end side of the lens unit 200. Two types of concave leads 296 and 293 are arranged on the inner surface of the zoom ring 202.

  The concave lead 296 provided as an example of the second concave lead engages the lead portion 257 of the engaging member 285 attached to the cam cylinder 205 as an example of the second convex lead. Therefore, when the zoom ring 202 is rotated, a part of the rotational movement of the zoom ring 202 is transmitted to the cam cylinder 205 through the engaging member 285.

  Although the concave leads 293 and 296 are both formed in a spiral shape, the inclination with respect to the optical axis X is different from each other. In other words, the concave lead 296 arranged alone makes a relatively large angle α with respect to the plane XY perpendicular to the optical axis Z of the lens unit 200. On the other hand, the plurality of concave leads 293 arranged in parallel have a relatively small angle with respect to the plane XY.

  For this reason, the single concave lead 296 intersects with the concave lead 293 at a plurality of locations. At the intersections of the concave leads 296 and 293, the end portions of the other concave leads 296 and 293 open on the side walls of the concave leads 296 and 293, respectively. However, the single concave lead 296 is formed deeper than the other concave leads 293. This prevents the guide by the concave lead 296 from being interrupted at the intersection.

Further, the length B ₁ of the lead portion 257 that engages with the concave lead 296 is sufficiently longer than the width A ₁ of the opening at the intersection. Therefore, the concave lead 296 and the engaging member 285 are always engaged by contact between surfaces, not point contact or line contact. Thereby, the concave lead 296 guides the lead portion 257 with high accuracy over the entire length.

In the intersection of the concave leads 296,293, also in the concave lead 293, to the side wall, occurs an opening width _{A 2.} The lead piece 292 of the rectilinear cylinder 203 is engaged with the concave lead 293. The straight cylinder 203 will be described next.

  FIG. 9 is a development view showing a layout on the outer peripheral surface of the rectilinear cylinder 203. The upper side in the figure corresponds to the front end side of the lens unit 200. The rectilinear cylinder 203 has a rectilinear key 255, an opening 258, and a lead piece 292.

  The rectilinear key 255 is engaged with the rectilinear groove 288 of the guide cylinder 206 to restrict the rotation of the rectilinear cylinder 203. The opening 258 exposes a part of the surface of the cam cylinder 205 when the cam cylinder 205 is incorporated inside the rectilinear cylinder 203. Thereby, for example, the engaging member 285 can be assembled to the cam cylinder 205 incorporated inside the straight advance cylinder 203.

  That is, the engaging member 285 is attached by screwing the attachment portion 256 to the outer peripheral surface of the cam cylinder 205 at the wide insertion portion 259 provided at the end of the opening 258. In the attached engaging member 285, the lead portion 257 is extended to the outer peripheral surface side of the rectilinear cylinder 203.

Therefore, when the cam cylinder 205 rotates with respect to the rectilinear cylinder 203, the lead portion 257 moves along the outer peripheral surface of the rectilinear cylinder 203. Thus, in the straight tube 203 and, at the same time with minimal area of the opening 258 to secure the surface area of the rectilinear barrel 203 so as to ensure sufficient length B ₁ to the lead portion 257.

  In the rectilinear cylinder 203, the lead piece 292 engages with a plurality of concave leads 293 provided in parallel with the zoom ring 202. Therefore, the straight cylinder 203 is provided with the same number of lead pieces 292 as the concave leads 293 in the zoom ring 202.

  Each of the lead pieces 292 has a parallelogram plane shape following the side wall of the concave lead 293. Therefore, the lead piece 292 and the concave lead 293 are engaged not by point contact or line contact but by contact between surfaces.

The length B ₂ in the longitudinal direction of the lead piece 292 is sufficiently longer than the width A ₂ of the opening in the side wall of the concave lead 293. Accordingly, the concave lead 296 thereby guides the lead portion 257 with high accuracy over the entire length.

  In the rectilinear cylinder 203, the lead piece 292 is disposed near the rear end of the rectilinear cylinder 203. The concave lead 293 extends to the front end of the inner surface of the zoom 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.

  As described above, in the rectilinear cylinder 203, a plurality of lead pieces 292 that engage with the concave lead 293 are provided on the circumference of the rectilinear cylinder 203, so that the positioning of the rectilinear cylinder 203 by the zoom ring 202 is stabilized. Further, the rectilinear cylinder 203 is engaged with the rectilinear grooves 288 of the guide cylinder 206 at a plurality of rectilinear keys 255 provided on the inner surface of the rearmost end separated from the position of the lead piece 292 in the optical axis Z direction. Therefore, it is possible to prevent the inclination of the rectilinear cylinder 203 with respect to the optical axis Z from shifting.

  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. 10 is a development view showing a layout on the outer peripheral surface of the guide tube 206. The upper side in the figure corresponds to the front end side of the lens unit 200. The guide tube 206 has a rectilinear groove 288 and a concave lead 294.

  In the guide tube 206, a plurality of rectilinear grooves 288 are arranged extending in the optical axis Z direction. The concave lead 294 formed in a spiral shape is inclined at an angle γ with respect to a plane XY perpendicular to the optical axis Z of the lens unit 200 in the drawing. Further, two concave leads 294 are paired, and a plurality of pairs are arranged in the guide tube 206. For this reason, each of the rectilinear grooves 288 intersects with the two concave leads 294.

  At the intersection with the concave lead 294, the end of the concave lead 294 opens on the side wall of the rectilinear groove 288. However, the rectilinear groove 288 is formed deeper than the concave lead 294. This prevents the guide for the straight key 255 in the straight groove 288 from being interrupted at the intersection.

In addition, at the intersection with the rectilinear groove 288, the end of the rectilinear groove 288 opens on the side wall of the concave lead 294. Here, when measuring the longitudinal direction of the concave lead 294, the opening of the rectilinear groove 288 end has a width A _3.

  However, since the pair of concave leads 294 are at different positions in the circumferential direction of the guide tube 206, the positions of the openings are also shifted from each other. Therefore, it is prevented that the guidance by the pair of concave leads 294 is lost at the same time.

  FIG. 11 is a development view when the layout on the inner peripheral surface of the cam cylinder 205 is viewed from the outer peripheral surface side. The upper side in the figure corresponds to the front end side of the lens unit 200. The cam cylinder 205 has a convex lead 253 and a drive cam groove 254 on the inner peripheral surface.

  On the inner peripheral surface of the cam cylinder 205, first, a plurality of drive cam grooves 254 are arranged. Each of the drive cam grooves 254 has a complicated shape and occupies a large area on the inner peripheral surface of the cam cylinder 205. On the other hand, the convex lead 253 sews the gap of the drive cam groove 254 and draws a spiral intermittently.

  Here, the convex lead 253 is formed to protrude from the inner peripheral surface of the cam cylinder 205, and the drive cam groove 254 is recessed from the inner peripheral surface of the cam cylinder 205. Therefore, the convex lead 253 and the drive cam groove 254 cannot be crossed. For this reason, the convex lead 253 is omitted in the section intersecting with the drive cam groove 254.

However, even a short ones of the convex lead 253 sections and has a length B ₃ as shown by the two-dot chain line in the figure. This length B ₃ is sufficiently wider than the width A _{3 of the} opening formed in the side wall of the concave lead 294 shown in FIG. Therefore, the convex lead 253 and the concave lead 294 that are engaged with each other are always engaged not by point contact or line contact but by contact between surfaces. Thereby, the concave lead 294 of the guide cylinder 206 guides the convex lead 253 of the cam cylinder 205 while maintaining high accuracy.

  Further, a part of the convex lead 253 is disposed on the rear end side of the cam cylinder 205. Therefore, even when the cam cylinder 205 is drawn forward from the guide cylinder 206, the cam cylinder 205 is engaged with the guide cylinder 206 by the large number of convex leads 253. Therefore, the extended cam cylinder 205 is accurately positioned with respect to the guide cylinder 206.

  In the lens unit 200 having the zoom ring 202, the rectilinear cylinder 203, the guide cylinder 206, and the cam cylinder 205 having the layout as described above, when the zoom ring 202 is rotated, a lead piece 292 is provided on the concave lead 293 of the zoom ring 202. The rectilinear cylinder 203 engaged in the step moves in the optical axis Z direction without rotating. As a result, the cam cylinder 205 moves in the direction of the optical axis Z along with the rectilinear cylinder 203.

  Further, the cam cylinder 205 is engaged with the concave lead 294 of the guide cylinder 206 by the convex lead 253 on the inner peripheral surface. Therefore, when moving in the optical axis Z direction along with the rectilinear cylinder 203, the cam cylinder 205 rotates around the optical axis Z according to the lead amounts of the concave lead 294 and the convex lead 253.

Now, assuming that the amount of movement of the rectilinear cylinder 203 caused by the rotation operation of the zoom ring 202 is X ₁ [mm] and the amount of rotation of the zoom ring 202 is Y ₁ [°] according to the rotation angle, the lead Z ₁ [ mm] can be calculated according to Equation 1 below. Therefore, for example, when the amount of extension of the straight cylinder 203 is set to 30 [mm] and the amount of rotation of the zoom ring 202 is set to 180 [°], the lead of the lead piece 292 may be set to 60 [mm].
Z ₁ = (X ₁ × 360) / Y ₁ Formula 1

On the other hand, when considering the cam cylinder 205, when the rectilinear cylinder 203 moves in the optical axis Z direction to the movement amount X ₁ [mm], the cam cylinder 205 also moves to the same movement amount. Therefore, when the movement amount of the cam cylinder 205 is X ₁ [mm] and the rotation angle of the cam cylinder 205 is Y ₂ [°], the lead Z ₂ [mm] of the concave lead 294 of the guide cylinder 206 is It can be calculated according to Equation 2. Thus, when the feed amount of the cam barrel 205 is 30 [mm], to the amount of rotation of the cam barrel 205 to 90 [°], as lead _{Z 2} recessed lead 294 is 120 [mm] do it.
Z ₂ = (X ₁ × 360) / Y ₂ Formula 2

  In the lead structure having the lead amount calculated as described above, the inclination β (see FIG. 8) of the concave lead 293 that drives the rectilinear cylinder 203 in the zoom ring 202 is the inclination γ of the concave lead 294 in the guide cylinder 206. (See FIG. 10). Therefore, the rotation amount of the cam cylinder 205 caused by the rotation of the zoom ring 202 is smaller than the rotation amount of the zoom ring 202.

  As described above, in the lens unit 200, the rectilinear cylinder 203 and the cam cylinder 205 having the same feeding amount are driven by the concave leads 293 and 294 having different inclinations. Thereby, the rotation amount of the cam cylinder 205 can be reduced with respect to the rotation amount of the zoom ring 202.

  Therefore, in the zoom ring 202, the count value of the encoder formed by the brush 252 and the flexible substrate 251 can be increased to detect the rotation amount of the zoom ring 202 with high accuracy. Further, since the rotation amount of the cam cylinder 205 is smaller than the rotation amount of the zoom ring 202, the lengths of the individual drive cam grooves 254 and 291 can be shortened on the peripheral surface of the cam cylinder 205 having a limited surface area. Therefore, the degree of freedom of the layout of the drive cam grooves 254 and 291 in the cam cylinder 205 can be improved.

  When the zoom ring 202 is rotated in the lens unit 200, the cam cylinder 205 is directly engaged with the concave lead 296 of the zoom ring 202 by the lead portion 257 of the engagement member 285. Thereby, the rotation of the zoom ring 202 is efficiently transmitted to the cam cylinder 205.

Here, the lead Z ₃ [mm] of the concave lead 296 can be calculated according to the following Equation 3. Specifically, for example, in the case feed amount of the cam barrel 205 is 30 [mm], the rotation amount _{Y 2} [°] and the difference of the rotation amount _{Y 1} [°] and the cam barrel 205 of the zoom ring 202 (Y _{In order to set 1−} Y ₂ ) to 90 °, the lead Z ₃ of the concave lead 296 may be set to 120 mm.
_{Z 3 = (X 1 × 360} ) / (Y 1 -Y 2) ··· Equation 3

  In the lead structure having the lead amount calculated as described above, the concave lead 296 engaged with the lead portion 257 in the zoom ring 202 has an inclination α (see FIG. 8). Therefore, a rotation amount smaller than the rotation amount of the zoom ring 202 is transmitted to the cam cylinder 205.

  In this way, by combining a plurality of lead structures, a lens barrel having a high expansion / contraction ratio can be formed while maintaining a high positioning accuracy of the optical member, and a lens unit 200 having a high magnification and a high quality can be formed.

  Further, since the rotation amount of the zoom ring 202 can be increased without increasing the size of the cam cylinder 205, the detection accuracy of the rotation amount can be improved, which contributes to the downsizing of the lens unit 200.

  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 provided with a plurality of optical members 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.

DESCRIPTION OF SYMBOLS 100 Camera system, 200 Lens unit, 201 Fixed cylinder, 202 Zoom ring, 203 Straight advance cylinder, 204 First cylinder, 205 Cam cylinder, 206 Guide cylinder, 207 First moving frame, 208 Lens side mount part, 209 Second 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, 251 Flexible substrate, 252 Brush, 253 Convex lead, 254 291 Drive cam groove, 255 Linear key, 256 Mounting portion, 257 Lead portion, 258 Opening portion, 259 Insertion portion, 261 Screw insertion hole, 262 Non-rotating hole, 270 Feed screw assembly, 272 Stepping motor, 274 Feed screw, 276 frame, 278 rack member, 281, 28 3, 284 cam pin, 282 rectilinear piece, 285 engaging member, 286 bayonet claw, 288, 297 rectilinear groove, 289 impact resistant piece, 290 groove end opening, 292 lead piece, 293, 294, 296 concave lead, 295 positioning part, 299 Shock-resistant cam 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 Penta prism, 356 Finder optical system, 360 Body side mount part, 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 Ra pivot shaft, 380 focusing optics, 382 focus detection sensor 390 photometer

Claims (11)

A fixed guide tube having one of a helical first convex lead and a first concave lead engaging each other;
An operation ring having one of a spiral second convex lead and a second concave lead that engage with each other, and rotating with respect to the guide tube in accordance with a user operation;
And having the other of the first convex lead and the first concave lead and the other of the second convex lead and the second concave lead, and when rotational motion is transmitted from the operating ring, A lens barrel comprising: a drive barrel that drives an optical member by a rotational motion having a rotation amount smaller than the rotation amount. The operation ring has one of a spiral third convex lead and a third concave lead that are provided separately from the second convex lead and the second concave lead and engage with each other.
The other of the third convex lead and the third concave lead, and when the operation ring rotates, a part of the rotational movement transmitted from the operation ring is converted into a straight movement, and the optical member The lens barrel according to claim 1, further comprising a rectilinear barrel that moves in the optical axis direction.   The lens barrel according to claim 2, wherein the second convex lead penetrates an opening provided in the rectilinear tube in a radial direction of the lens barrel and engages with the second concave lead. The drive cylinder has one of a cam groove and a cam pin that engage with each other;
The optical member has the other of the cam groove and the cam pin,
The lens barrel according to any one of claims 1 to 3, wherein the optical member is driven in an optical axis direction of the optical member by a rotational movement of the drive barrel.   In the operation ring, the one of the second convex lead and the second concave lead is inclined with respect to a plane perpendicular to the optical axis of the optical member, rather than the one of the third convex lead and the third concave lead. The lens barrel according to claim 2, wherein is large.   The second convex lead is continuous with the direct engagement portion, part of which is in close contact with one of the operation ring and the drive cylinder, and is continuous from the direct engagement portion in the longitudinal direction of the second convex lead, and The lens barrel according to claim 2, further comprising an extension engagement portion that is separated from one of the operation ring and the drive cylinder.   7. The lens barrel according to claim 5, wherein the second convex lead passes through an opening provided in the rectilinear barrel in a radial direction of the lens barrel and engages with the second concave lead. 8. . The drive cylinder has one of a cam groove and a cam pin that engage with each other;
The optical member has the other of the cam groove and the cam pin,
The lens barrel according to any one of claims 5 to 7, wherein the optical member is driven in an optical axis direction of the optical member by a rotational movement of the drive barrel.   Either the first convex lead or the first concave lead has a locus intersecting with the cam groove, and the other of the first convex lead and the first concave lead is based on the width of the cam groove. The lens barrel according to claim 4 or 8, wherein the lens barrel contacts the one side over a long section. One of an encoder and a scale having a fixed relative position to the guide tube;
The encoder further comprising the encoder that moves together with the operation ring and the other of the scale, wherein the encoder detects a rotation amount of the operation ring by measuring a relative movement amount with respect to the scale. The lens barrel according to any one of the above.   An imaging apparatus comprising the lens barrel according to any one of claims 1 to 10.

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