JP2010169929A - Lens barrel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a lens barrel for securing positional accuracy without falling the movable lens frame in an optical axis direction by gravity even when the camera is made downward, in the lens barrel, which includes a rotational frame supported to be rotatable around an optical axis to a fixed frame and in which the rotational frame is rotated when a movable lens group moves in the direction of the optical axis. <P>SOLUTION: In the lens barrel, a rotation resisting impartion membe, which imparts rotation resistance by abutting on the rotational frame from a direction parallel to the optical axis, is supported to the fixing frame. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a lens barrel, and more particularly to a mechanism for preventing a lens group (lens frame) supported by a fixed member so as to be movable in the optical axis direction from dropping due to its own weight.

  In single-lens reflex cameras, the use of electric AF has become commonplace, and the focus lens group can be moved in the optical axis direction with the lightest possible force in order to reduce the load on the electric drive system and reduce the size. preferable.

JP 59-029211 Japanese Utility Model Publication No. 61-31284 Japanese Utility Model Publication No. 63-015849 Japanese Examined Patent Publication No. 7-69505 JP-A-10-333015

  However, the fact that the focus lens group can move in the optical axis direction with a light force means that there is a possibility that the camera will fall under its own weight when the camera is held downward, for example. For this reason, conventionally, a special locking mechanism has been provided. However, providing a special lock mechanism leads to complication and enlargement, and is disadvantageous in terms of cost. Similar problems occur not only with the focus lens group but also with the zoom lens group.

  An object of the present invention is to obtain a lens barrel capable of ensuring positional accuracy without causing a movable lens frame to fall by its own weight even when the camera is faced down, based on the above problem awareness. .

  The lens barrel of the present invention has a rotating frame that is rotatably supported around the optical axis with respect to the fixed frame, and the rotating frame is used when the movable lens group moves in the optical axis direction. In the rotating lens barrel, the fixed frame body is supported by a rotation resistance applying member that abuts against the rotation frame body from a direction parallel to the optical axis and applies rotation resistance.

  The present invention is particularly useful when applied to a lens barrel in which a rotating frame is rotatably supported by a fixed frame via a bearing.

  Specifically, the rotation resistance applying member includes a contact member that contacts the surface orthogonal to the optical axis of the rotating frame, and an urging member that urges the contact member toward the surface orthogonal to the optical axis. can do.

  The contact member can be constituted by a rolling member (ball, roller) that can roll with the rotation of the rotating frame, or a simple contact member that simply contacts the rotating frame.

  The rotating frame is composed of an annular member having, for example, a large-diameter portion, a small-diameter portion, and a flange portion orthogonal to the optical axis connecting the large-diameter portion and the small-diameter portion. Can be brought into contact with the portion.

  The rotating frame body, the fixed frame body, and the rotation resistance applying member are unitized, and the fixed frame body of the unitized rotating unit can be fixed to another fixed frame body of the lens barrel.

  The lens barrel of the present invention has a lens group that is movable in the optical axis direction and a rotating frame body that is rotatably supported about the optical axis with respect to the fixed frame body. In the lens barrel that rotates when moving in the axial direction, a rotating resistance applying member that abuts against the rotating frame from the direction parallel to the optical axis and applies rotational resistance to the fixed frame is supported. Even so, the positional accuracy can be ensured without the weight of the movable lens frame dropping in the optical axis direction.

It is a longitudinal cross-sectional view which shows one Embodiment of the lens-barrel by this invention. It is the same exploded perspective view. It is the upper half sectional view on which the element fixed to the inner side fixed ring of the lens barrel and the element supported rotatably on the outer peripheral surface of the inner side fixed ring are drawn. FIG. 4 is an upper half cross-sectional view at a different cross-sectional position from FIG. 3, depicting elements fixed to the inner fixed ring of the lens barrel and elements rotatably supported on the outer peripheral surface of the inner fixed ring. It is an upper half sectional view showing the element currently fixed to the movable lens frame of the lens barrel. It is a systematic diagram showing an AF driving system for a distance ring of the lens barrel. It is sectional drawing which follows the VII-VII line of FIG.

  The figure shows an embodiment in which a lens barrel according to the present invention is applied to a single-lens reflex single-focus interchangeable lens barrel 10. First, the overall structure of the lens barrel 10 will be described. As shown in FIG. 1, the lens barrel 10 includes a mount ring 11, a joint ring 12, an outer fixed cylinder 13, and an inner fixed ring 14 as fixed side members fixed to a camera body (not shown).

  The inner fixed ring 14 is formed with a rectilinear guide groove 14a parallel to the optical axis. The rectilinear guide groove 14a is formed on the outer periphery of the movable lens frame 20 that is fitted to the inner periphery of the inner fixed ring 14 so as to be relatively movable. A rectilinear guide piece (also referred to as a rotation transmission piece) 20a that is fitted to be freely movable and protrudes outward in the radial direction is fixed. The lens system of this embodiment includes a movable focus lens group LM fixed to the movable lens frame 20 and a fixed lens group LF fixed to a fixed lens frame 15 fixed to the mount ring 11. .

  FIG. 5 shows elements fixed to the movable lens frame 20. A front frame 20F and a rear frame 20R are fixed to the front and rear of the movable lens frame 20, and a diaphragm block S is fixed between the front frame 20F and the rear frame 20R. The movable focus lens group LM supported by the front frame 20F and the rear frame 20R has a simplified configuration. From the aperture block S, an aperture interlocking rod SB that is interlocked with the aperture member on the camera body side protrudes.

  A focus ring 21 (FIGS. 1 and 7) is rotatably supported between the front end portion of the outer fixed cylinder 13 and the front end portion of the inner fixed ring 14, and on the inner peripheral side of the focus ring 21, A distance ring 22 is rotatably supported with respect to the outer fixed cylinder 13. An inner gear 22G is formed in the inner periphery of the rear end of the distance ring 22, and a pinion 23P of an electric drive system (ultrasonic motor) 23 is engaged with the inner gear 22G as shown in FIG. The pinion 23P is driven forward and backward via a clutch mechanism 23C, and the electric drive system 23 is controlled by an AF control mechanism 23X in the camera body and a motor drive circuit 23Y in the lens barrel 10. The

  A lead ring 24 is located on the inner peripheral side of the distance ring 22, and a clutch ring 25 is located on the front side. The distance ring 22 and the lead ring 24 are fixed by a fixing screw 26a (FIG. 3), and the clutch ring 25 and the lead ring 24 are fixed by a fixing screw 26b and a nut 26c (FIG. 4). , 24, 25) are integrated. A lead groove 24L (FIGS. 1 and 2) is formed on the inner peripheral surface of the lead ring 24, and the straight guide piece 20a of the movable lens frame 20 is formed in the lead groove 24L. Is inserted. Therefore, when the lead ring 24 (distance ring 22) is driven to rotate in the forward and reverse directions, the movable lens frame 20 (movable focus lens group LM) emits light through the lead groove 24L, the rectilinear guide piece 20a, and the rectilinear guide groove 14a. Move straight in the axial direction. This operation is an AF operation.

  The focus ring 21 is an operation ring that moves the movable lens frame 20 forward and backward in the direction of the optical axis when separated from the above AF operation (separately) when manually rotated forward and backward. The following clutch mechanism (internal / external rotation one-way transmission mechanism) 30 (FIGS. 1, 2, and 7) is interposed between the focus ring 21 and the clutch ring 25.

  A clutch transmission ring 31 is supported on the outer peripheral surface of the inner fixed ring 14 so as to rotate integrally with the focus ring 21. Specifically, a washer 32 is positioned on the rear surface of the outer flange 14F at the front end of the inner fixed ring 14, and a drive plate 35 is attached to the washer 32 via a roller 34 supported by the retainer ring 33. It is supported rotatably. The axis of the roller 34 faces the radial direction of the lens barrel 10. The radial protrusion 35a of the drive plate 35 is fitted into the rotation transmission groove 21a (FIG. 1) of the focus ring 21 through the rotation transmission groove 31a (FIGS. 1 and 2) of the clutch transmission ring 31. The drive plate 35 is always pressed against the roller 34 by a compression spring 36 inserted between the drive plate 35 and the clutch transmission ring 31.

  The clutch mechanism 30 includes a symmetrical roller storage wedge groove 31b (FIG. 7) formed on the outer peripheral surface of the clutch transmission ring 31, and a roller set 37 inserted into the roller storage wedge groove 31b. Four sets of roller storage wedge grooves 31b and roller sets 37 are provided spaced apart in the circumferential direction. As shown in FIGS. 2 and 7, the roller set 37 has a center roller 37A with the axis line oriented in the radial direction of the lens barrel 10 and axis lines located on both sides of the center roller 37A in a direction parallel to the optical axis. The pair of both side rollers 37 </ b> B are in contact with the inner peripheral surface of the clutch ring 25. This mechanism is known, and when rotation is input from the clutch transmission ring 31 side, the clutch ring 25 is rotated together by the wedge force acting between the inclined surface of the roller storage wedge groove 31b and the pair of both side rollers 37B. On the other hand, when rotation is input from the clutch ring 25 side, the pair of both side rollers 37B idle and do not transmit the rotation to the clutch transmission ring 31 (focus ring 21). Accordingly, when the clutch transmission ring 31 is rotated forward and backward via the focus ring 21, the rotation is transmitted from the clutch ring 25 to the lead ring 24, and the movable lens frame 20 is moved to the optical axis as described in the AF operation. While focusing is performed by moving back and forth in the direction, when the clutch ring 25 rotates in the AF operation, only the clutch ring 25 (distance ring 22 and lead ring 24) rotates, and the focus ring 21 does not rotate.

  As described above, the lens barrel 10 can perform either the AF operation (electric focus adjustment by the pinion 23P) or the MF operation (manual focus adjustment by the focus ring 21) by the above configuration. In addition, in the present embodiment, the clutch ring 25 is rotatably supported by the inner fixed ring 14 via a bearing (steel ball) 38 so that the AF operation can be executed with a light force (FIGS. 1 to 4). ). That is, the clutch ring 25 has a front large-diameter portion 25A, a rear small-diameter portion 25B, and a flange portion (optical axis orthogonal surface) 25C that connects both. On the inner peripheral side of the clutch ring 25, a fixed ring 39 fixed on the outer periphery of the inner fixed ring 14 by a fixing screw 27a and a nut 27b (FIG. 3) is located. The fixed ring 39 and the clutch ring small-diameter portion 25B. A plurality of bearings (steel balls) 38 are located between the two. The bearings 38 are held at predetermined intervals in the circumferential direction by the retainer ring 40, and are held at a fixed position by a bearing retainer 41 that is screwed and fixed to the fixed ring 39. By this bearing (bearing) structure, the clutch ring 25 can be rotated with a small rotational resistance.

  On the other hand, if the rotational resistance of the clutch ring 25 is small, there arises a problem that the movable lens frame 20 falls by its own weight. That is, when the camera posture is tilted so that the front of the lens optical axis is lowered, the rotation operation (MF operation) of the focus ring 21 is not executed, and the driving operation (AF operation) of the pinion 23P is not executed. Since the rotational resistance of 25 (distance ring 22 and lead ring 24) is small, the movable lens frame 20 may fall by its own weight. In order to prevent this falling of its own weight, in this embodiment, the stationary ring 39 is provided with a rotation resistance applying member 42 that applies a rotation resistance to the clutch ring 25.

  The rotation resistance applying member 42 includes a ball (steel ball) 42a that abuts on the flange portion 25C of the clutch ring 25, and a compression spring 42b that applies a biasing force to the ball 42a toward the flange portion 25C. The stationary ring 39 is formed with an insertion through hole 39a in a direction parallel to the optical axis into which the rotation resistance applying member 42 (the ball 42a and the compression spring 42b) is inserted. The rotation resistance applying member 42 inserted into the insertion through hole 39a is prevented from being removed by a presser plate 44 fixed to the fixed ring 39 via a fixing screw 43 (FIGS. 1 and 4). The clutch ring 25, the bearing 38, the fixed ring 39, the retainer ring 40, the bearing retainer 41, the rotation resistance applying member 42, the fixing screw 43 and the retainer plate 44 fix the fixed ring 39 to the inner fixed ring 14. Unitized in the previous state.

  As described above, in this embodiment, the rotation resistance is applied to the clutch ring 25 whose rotation resistance is reduced by the bearing 38 by the rotation resistance applying member 42. The magnitude of this rotational resistance can be changed (set) by the strength of the compression spring 42b of the rotational resistance applying member 42. Whether the ball 42a is in rolling contact or sliding contact with the rotating clutch ring 25 may be in any form as long as a suitable rotational resistance (friction resistance) is applied to the clutch ring 25. . In the case of rolling contact, another rolling element (for example, a roller) can be used in place of the ball 42a, and a simple contact member (for example, felt) is used if no rolling contact is required and rotational resistance is provided only by sliding contact. be able to. In the illustrated embodiment, the rotational resistance applying member 42 is one (a set), but the rotational resistance can be finely adjusted by providing a plurality of rotational resistances apart from each other in the circumferential direction.

  As described above, according to the present embodiment, the rotational resistance is given to the clutch ring 25 that has once been subjected to low friction by the separate rotational resistance applying member 42, whereby the magnitude of the rotational resistance can be adjusted. In particular, by applying a load to the clutch ring 25 from a direction parallel to the optical axis, the rotation resistance applying structure can be realized simply without increasing the size.

  In the above embodiment, the rotation resistance is given to the clutch ring 25 that rotates when the movable focus lens group LM moves in the optical axis direction, but one of the other lens groups, for example, the zoom lens group, moves in the optical axis direction. Similarly, a rotation resistance can be applied to the rotating frame body that rotates to prevent the lens group from dropping its own weight. In the present invention, the lens group that moves in the optical axis direction and the interlocking mechanism of the rotating frame that rotates in conjunction with the movement of the lens group in the optical axis direction are not questioned. The interlocking rotation mechanism in the form is an example.

DESCRIPTION OF SYMBOLS 10 Lens barrel 11 Mount ring 12 Joint ring 13 Outer fixed cylinder 14 Inner fixed ring (another fixed frame)
14a Straight guide groove 14F Outer flange 15 Fixed lens frame 20 Movable lens frame 20a Straight guide frame 21 Focus ring 22 Distance ring 22G Inner gear 24 Lead ring 24L Lead groove 25 Clutch ring (rotating frame)
25A Front large diameter portion 25B Rear small diameter portion 25C Flange portion 26a 26b 27a Fixing screw 30 Clutch mechanism (internal / external rotation one-way transmission mechanism)
31 Clutch transmission ring 31a Rotation transmission groove 31b Roller storage wedge groove 32 Washer 33 Retainer ring 34 Roller 35 Drive plate 35a Radial protrusion 36 Compression spring 37 Roller set 37A Center roller 37B A pair of both side rollers 38 Bearing 39 Fixed ring (fixed frame) )
39a Insertion through hole 40 Retainer ring 41 Bearing retainer 42 Rotation resistance applying member 42a Ball (contact member)
42b Compression spring (biasing member)
43 Fixing screw 44 Presser plate LM Movable focus lens group LF Fixed lens group

Claims (7)

A lens group movable in the optical axis direction and a rotating frame body supported so as to be rotatable about the optical axis with respect to the fixed frame body. The rotating frame body rotates when the lens group moves in the optical axis direction. In a lens barrel that
A lens barrel characterized in that a rotating resistance applying member that abuts against the rotating frame from a direction parallel to the optical axis and applies rotational resistance to the fixed frame is supported. The lens barrel according to claim 1, wherein the rotating frame is rotatably supported by a fixed frame through a bearing. 3. The lens barrel according to claim 1, wherein the rotation resistance applying member is attached to a contact member that contacts a surface orthogonal to the optical axis of the rotating frame, and the contact member faces the surface orthogonal to the optical axis. A lens barrel comprising a biasing member that biases. 4. The lens barrel according to claim 3, wherein the abutting member is a rolling member that can roll as the rotating frame rotates. 4. The lens barrel according to claim 3, wherein the contact member is a simple contact member that simply contacts the rotating frame. The lens barrel according to any one of claims 1 to 5, wherein the rotary frame includes a large diameter portion, a small diameter portion, and a flange portion orthogonal to an optical axis connecting the large diameter portion and the small diameter portion. A lens barrel that contacts the flange portion. 7. The lens barrel according to claim 1, wherein the rotating frame body, the fixed frame body, and the rotation resistance applying member are unitized, and the fixed frame body of the unitized rotating unit. Is a lens barrel fixed to another fixed frame of the lens barrel.

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