JP2008046440A - Lens barrel with focus adjustment mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens barrel, with which a coupled state between a focus operation ring and a focus drive ring, which constitute the focus adjustment mechanism of the lens barrel can be stabilized. <P>SOLUTION: The lens barrel with focus adjustment mechanism is provided with a focus operation ring 4 operated to turn about the optical axis, and the focus drive ring 3 coupled with the focus operation ring to be integrally turned therewith, and moving a focus lens L2 in the optical axis direction to perform focus adjustment, and is equipped with a coupling hole 71, provided to the focus operation ring 4 and having a prescribed length in the circumferential direction, a collar 72 inserted internally in the coupling hole 71 and set so that its outside surface is frictionally engaged with the inner surface of the coupling hole, and a machine screw 73 inserted through the shaft hole of the collar 72 from the outside diameter side and tightened to the focus drive ring 3. Even when the machine screw 73 becomes loose, the coupling of the focus operation ring 4 and the focus drive ring 3 is held by the frictional engagement of the collar 72 with the coupling hole 71. Focus adjustment is facilitated, and reliability in the coupling state of both of them is enhanced. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a lens barrel of a camera, and more particularly to a lens barrel with an improved focus adjustment mechanism in a lens barrel having a zoom mechanism.

  In a lens barrel of a camera equipped with a zoom mechanism, the focus position (focal position) may change when the focal length is changed by the zoom mechanism. Even when the focal length is changed, the structure of the lens barrel that keeps the focus position constant is inevitable, and it is difficult to reduce the cost. In particular, in a lens barrel composed of a plurality of lenses or lens groups, it is difficult to keep the focus position constant in an inner focus lens barrel that adjusts focus by moving a lens other than the front group or the last group. is there. For this reason, when the focal length is changed by the zoom mechanism, it is necessary to operate the focus operation ring to perform focusing with the focus lens. In this way, since the distance scale displayed on the focus operation ring is highly important in the inner focus lens, focus adjustment is performed for either the tele (long focus) or wide (short focus) infinity position of the zoom mechanism. The structure to do is taken.

For example, the zoom lens barrel described in Patent Document 1 is not an inner focus lens barrel, but a focus cam ring for performing focus adjustment by moving the focus lens in the optical axis direction and a focus operation operated during focus adjustment. The ring is connected with a screw. In such a lens barrel, in order to perform the focus adjustment described above, the hole through which the screw connecting the focus operation ring and the focus cam ring is inserted is a long hole extending in the direction around the optical axis, that is, in the circumferential direction. It is configured, and the relative rotation position of the focus operation ring and the focus cam ring is changed and adjusted by loosening the screw and moving it within the elongated hole. Thereby, when the focus lens is adjusted to a predetermined position in the optical axis direction, the focus operation ring can be set to be a predetermined rotation position.
Utility Model Registration No. 2584208

  In the configuration in which the focus operation ring and the focus cam ring are simply connected by screws as in Patent Document 1, the connection state is maintained only by the frictional engagement force generated by the surface contact between the screw head and the outer peripheral surface of the focus operation ring. There must be. In recent years, there has been a tendency for the diameter and head dimensions of the screw to be reduced in order to reduce the size of the lens barrel, so that the connecting force between the focus operation ring and the focus cam ring due to the screw has decreased, and the focus operation ring and the focus The cam ring is likely to be displaced in the direction around the optical axis. In particular, when the screw is loosened due to secular change or external vibration, the frictional engagement force at the contact surface between the screw head and the outer periphery of the focus operation ring is reduced even if the screw is slightly loosened. When the focus operation ring is operated, slipping occurs between the screw and the elongated hole, and the connection state between the two is lost. Therefore, there is a difference between the rotation amount of the focus operation ring and the rotation amount of the focus cam ring, and an error occurs between the distance scale of the focus operation ring and the actual subject distance by the focus lens. Such a problem can also be said for a focus mechanism configured to move the focus lens in the optical axis direction by a screw (lead screw) ring instead of the focus cam ring. In the present specification, a ring member for moving the focus lens in the optical axis direction like the focus cam ring and the focus screw ring is referred to as a focus drive ring.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a lens barrel having a focus adjustment mechanism that stabilizes a connection state between a focus operation ring and a focus drive ring.

  The present invention includes a focus operation ring that is rotated around an optical axis, a focus drive ring that is connected to the focus operation ring and is integrally rotated, and performs focus adjustment by moving a focus lens in the optical axis direction. A connecting hole having a required length in the circumferential direction provided in a ring member disposed on the outer diameter side in a portion connecting the focus operation ring and the focus driving ring, and in the connecting hole A collar that is inserted and whose outer surface is frictionally engaged with the inner surface of the connection hole, and a screw that is inserted into the shaft hole of the collar from the outer diameter side and fastened to a ring member that is disposed on the inner diameter side. Features.

  According to the present invention, the focus operation ring and the focus drive ring are maintained in a connected state by the frictional engagement force with the outer diameter side ring member with which the head of the screw fastened to one of the ring members abuts. At the same time, the connected state is also maintained by the frictional engagement force between the collar inserted into the connecting hole provided in the ring member on the outer diameter side and fixed by the screw and the inner surface of the connecting hole. Therefore, when the screw is loosened, the focus operation ring and the focus drive ring can be rotated relative to each other to enable focus adjustment, while the connection between the focus operation ring and the focus drive ring is secured when the screw is fastened. In particular, even when the screws are loosened, the connection state of both ring members by the collar can be made stable and reliable.

  As a preferred form of the lens barrel of the present invention, the connecting hole is a long hole having a long side in the direction around the optical axis, and the collar and the screw are relatively movable in the long side direction inside the connecting hole. Thereby, it is possible to adjust the focus in the length range of the long side of the connecting hole.

  The collar is formed of a cylindrical body having a flat surface formed on at least a part of the side surface, and the flat surface is in contact with the inner surface of the connecting hole extending in the circumferential direction. The flat surface of the collar and the flat inner surface of the connecting hole are in close contact with each other, the frictional engagement force is increased, and the connected state is maintained. Further, since the head of the screw is in contact with the surface of the ring member on the outer diameter side at the peripheral edge of the connection hole, the connected state is maintained even if the frictional engagement force between the head and the ring member is applied. In particular, the inner dimension of the upper hole in the thickness direction of the connecting hole is made larger than the inner dimension of the lower hole, and the head of the screw abuts the bottom of the upper hole, so that the screw head and the outer diameter side ring Ensures frictional engagement with the member.

  In the lens barrel of the present invention, for example, a part of the focus operation ring is overlapped with a part of the focus drive ring from the outer diameter direction, a connection hole is provided in a part of the focus operation ring, and a screw is provided on the focus drive ring. Screwed onto the outer peripheral surface. In the lens barrel of the present invention, the focus drive ring may be a focus cam ring that is cam-engaged with the focus lens, or a focus screw ring that is screwed to the focus lens.

  Next, Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of the region above the optical axis Ox of the lens barrel OS of Example 1 configured as an interchangeable lens of a single-lens reflex camera. Embodiment 1 shows a lens barrel in which first to fifth lenses or lens groups are housed in a lens barrel. The lens barrel OS is divided into a front ring 11 and a rear ring 12 along the optical axis direction, and includes an inner fixed ring 1 integrated with screws 13. The first lens L1 is fixed by one lens frame F1. A fifth lens L5 is fixed to the rear end portion of the inner fixed ring 1 by a fifth lens frame F5. The rear end portion of the inner fixed ring 1 is configured as a bayonet portion 14 that can be attached to and detached from the lens mount of the camera body that does not appear in the drawing. A second lens L2 is supported in the front ring 11 of the inner fixed ring 1 by a second lens frame F2, and can be moved in the optical axis direction along a straight groove 111 provided in the front ring 11. ing. Further, the third lens L3 and the fourth lens L4 are supported in the rear ring 12 by the third lens frame F3 and the fourth lens frame F4, respectively, and along the rectilinear groove 121 provided in the rear ring 12. Each is movable in the optical axis direction. Further, an outer stationary ring 2 including a front outer ring 21 and a rear outer ring 22 is provided integrally with the inner stationary ring 1 so as to cover the front ring 11 and the rear ring 12. The lens barrel OS of the first embodiment is configured as a so-called inner focus lens barrel. As will be described later, the second lens L2 is configured as a focus lens, and the position of the second lens L2 in the optical axis direction is adjusted. In this way, the subject image to be photographed is focused.

  A focus cam ring 3 is fitted on the outer periphery of the front ring 11 of the inner fixed ring 1. The focus cam ring 3 is connected to the focus operation ring 4 by a focus adjustment mechanism 7 which will be described later, and can be rotated integrally around the optical axis of the lens barrel as the focus operation ring 4 rotates. The focus operation ring 4 is provided with a stop lever 41 at a part of the circumference in the inner diameter direction. The stop lever 41 is engaged with a circumferential groove 22a provided at the front end of the rear outer ring 22, The rotation operation is made possible within the circumferential range of the circumferential groove 22a. As shown in FIG. 2 in which the schematic structure of the front ring 11 and the focus cam ring 3 including the focus adjustment mechanism 7 is shown, a focus cam groove 31 having a required shape is formed in the focus cam ring 3, and the second lens frame. A roller R2 erected on the outer periphery of F2 in the outer diameter direction is engaged with the straight advance groove 111 of the front ring 11 and the cam groove 31 of the focus cam ring 3 in a penetrating state. Further, a zoom cam ring 5 is fitted and disposed on the outer periphery of the rear ring 12 of the inner fixed ring 1, and the zoom operation ring 6 is configured to be rotatable along the outer peripheral surface of the rear outer ring 22. It is engaged with a lever 61 projecting in the inner diameter direction, and can rotate integrally around the optical axis of the lens barrel as the zoom operation ring 6 rotates. The zoom cam ring 5 is formed with zoom cam grooves 51 and 52 having a required shape, and rollers R3 and R4 erected in the outer diameter direction on the outer circumferences of the third lens frame F3 and the fourth lens frame F4, respectively. The straight groove 121 of the rear ring 12 and the cam grooves 51 and 52 of the zoom cam ring 5 are engaged with each other. The straight grooves 111, 121, the cam grooves 31, 51, 52, and the rollers R2, R3, R4 of the lens frames F2, F3, F4 are circumferential directions when the lens barrel OS is viewed from the front. Are provided as a groove and a roller having the same shape at a central angle of 120 degrees around the optical axis of the lens barrel. The focus operation ring 4 and the zoom operation ring 6 are provided with decoration rings 42 and 62, respectively, to enhance the design appearance of each ring, and at the same time, provided on the outer ring 2 although not shown in the drawing. The focus operation ring 4 is provided with a distance scale so as to face the indicated index, and the zoom operation ring 6 is provided with a focal length scale.

  The general operation of the lens barrel OS will be described. Since the zoom cam ring 5 is integrally rotated when the zoom operation ring 6 is rotated, the crossing position of the zoom cam grooves 51 and 52 and the rectilinear groove 121 of the rear ring 12. Is changed in the optical axis direction, and the positions of the rollers R3 and R4 of the third lens frame F3 and the fourth lens frame F4 at the intersecting positions of these grooves are also changed in the optical axis direction, and are supported by these third lenses. The positions of L3 and the fourth lens L4 in the optical axis direction are changed and set to a desired zoom value, that is, a focal length. Similarly, when the focus operation ring 4 is rotated, the focus cam ring 3 is integrally rotated. Therefore, the intersection position of the focus cam groove 31 and the straight groove 111 of the front ring 11 is changed in the optical axis direction, and the groove The position of the roller R2 of the second lens frame F2 at the crossing position is also changed in the optical axis direction, and the position of the second lens L2 supported by the second lens frame F2 is changed and set in a focused state.

  In the lens barrel OS of the first embodiment, the focus operation ring 4 and the focus cam ring 3 are connected by the focus adjustment mechanism 7. The focus adjustment mechanism 7 is shown in FIG. The rear end portion in the optical axis direction of the focus cam ring 3 and the front end portion in the optical axis direction of the focus operation ring 4 are overlapped in the radial direction, and the focus operation ring 4 is long in the circumferential direction in this overlapped region. A rectangular connection hole 71 is penetrated in the radial direction. The inner dimension of the upper hole 71a in the thickness direction of the connecting hole 71 is slightly larger than the inner dimension of the lower hole 71b, and the cross-sectional shape in the thickness direction is formed in a T shape. A cylindrical collar 72 is inserted into the lower hole 71 b of the connection hole 71, and a screw 73 is inserted into the central shaft hole 72 a of the collar 72. The screw 73 is inserted into the outer periphery of the focus cam ring 3. It is screwed into a screw hole 74 provided on the surface. The collar 72 is formed in a substantially cylindrical shape, and has two flat surfaces 72b parallel to each other in the radial direction of the outer peripheral surface thereof, and the radial opposing dimensions of these flat surfaces 72b are the connecting holes. The inner diameter of the lower hole 71b of 71 is substantially equal to the inner dimension along the optical axis direction of the lens barrel. The shaft portion (screw portion) 73a of the screw 73 is slightly smaller in diameter than the inner diameter of the central shaft hole 72a of the collar 72, and the head portion 73b of the screw 73 is formed of the upper hole 71a of the connecting hole 71. It is smaller than the internal dimension along the optical axis of the lens barrel and slightly larger than the internal dimension along the optical axis of the lower hole 71b of the connection hole 71.

  In a state where the screw 73 is screwed into the screw hole 74 of the focus cam ring 3, as shown in the horizontal sectional view of FIG. 4A and the vertical sectional view taken along line AA of FIG. The head 73b of the screw 73 is housed in the upper hole 71a of the connecting hole 71, and at the same time is in contact with the upper surface of the upper hole 71a. Further, the collar 72 is fixed in the lower hole 71b of the connecting hole 71 by the screw 73, and the flat surfaces 72b on both sides of the collar 72 are in contact with both opposing inner side surfaces of the lower hole 71b. That is, the frictional force generated by the contact between the lower surface of the head 73 b of the screw 73 and the bottom surface of the upper hole 71 a of the connecting hole 71 and the flat surface 72 b of the collar 72 and the inner surface of the lower hole 71 b of the connecting hole 71 are abutted. The focus operation ring 4 and the focus cam ring 3 are connected in the circumferential direction by the frictional force generated by the contact. Needless to say, the focus operation ring 4 and the focus cam ring 3 are integrally connected in the optical axis direction of the lens barrel by a contact structure between the collar 72 fixed by the screw 73 and the connection hole 71.

  The procedure for adjusting the focus in the lens barrel of the first embodiment is as follows. First, the zoom operation ring 6 is rotated, the zoom cam ring 5 connected thereto is rotated, and the cam grooves 51 and 52 and the roller R3 are rotated. , R4 to change the optical axis positions of the third lens L3 and the fourth lens L4 to set a predetermined focal length, in this case, an infinite focal length. Then, the focus operation ring 4 is rotated, the focus cam ring 3 connected thereto is rotated, and the optical axis position of the second lens L2 is changed by the cam operation of the cam groove 31 and the roller R2. To focus. At this time, if the distance scale in the focus operation ring 4 is displaced, only the focus operation ring 4 is rotated using the connection structure 7 to correct the displacement of the distance scale. At this time, the focus cam ring 3 is prevented from rotating. In the correction by the focus adjusting mechanism 7, when the screw 73 is slightly loosened and the focus operation ring 4 is forcibly rotated around the optical axis of the lens barrel, the screw 73 and the collar 72 are integrated with the focus cam ring 3. Since it is in a fixed state, the connecting hole 71 is moved around the optical axis of the lens barrel while sliding with respect to the collar 72. Then, the screw 73 is fastened when the rotation position of the focus operation ring 4 is corrected, and the focus operation ring 4 and the focus cam ring 3 are integrally connected again by the screw 73. Thereby, as described above, the frictional force generated by the contact between the lower surface of the head 73b of the screw 73 and the bottom surface of the upper hole 71a of the connection hole 71, and the flat surface 72b of the collar 72 and the lower hole 71b of the connection hole 71 are obtained. The focus operation ring 4 and the focus cam ring 3 are connected by the frictional force generated by the contact with the inner surface. Therefore, thereafter, the correspondence between the focus operation ring 4 and the focus cam ring 3 becomes appropriate, and the focus adjustment is completed.

  According to this focus adjustment mechanism, at the time of focus adjustment, the screw 73 is loosened as described above, the relative rotation position of the focus operation ring 4 and the focus cam ring 3 is set or corrected, and then the screw 73 is again adjusted. It is only necessary to perform the fastening operation, and almost the same work as the conventional focus adjustment may be performed, and the focus adjustment can be easily performed. On the other hand, in the lens barrel that has been subjected to focus adjustment, the fastening state of the screw 73 may be loosened due to secular change, external vibration, or the like, and the head 73b of the screw 73 and the bottom surface of the upper hole 71a of the connecting hole 71 may be loosened. Even if the frictional force due to the contact may be reduced or lost, the connection state due to the frictional force generated between the flat surface 72b of the collar 72 and the inner surface of the lower hole 71b of the connection hole 71 is reduced. There is no. Particularly, since the area of the flat surface 72b of the collar 72 that contacts the lower hole 71b is larger than the area of the head 73b of the screw 73 that contacts the upper hole 71a, a large frictional engagement force on the flat surface 72b can be obtained. . Thereby, the connection state of the focus operation ring 4 and the focus cam ring 3 can be stabilized, and the reliability can be improved.

  Here, when the focus adjustment mechanism is actually configured, the manufacturing tolerances between the opposing dimensions in the radial direction of the flat surfaces 72b on both sides of the collar 72 and the internal dimensions in the optical axis direction of the lower hole 71b of the connecting hole 71 are provided. In some cases, it is difficult to obtain a frictional engagement force due to this tolerance. In this case, as shown in FIG. 5, the diameter of the central shaft hole 72a of the collar 72 is designed to be slightly larger than the diameter of the shaft 73a of the screw 73, and the screw 73 is fastened. In this case, a force in one direction (right direction in FIG. 5) in the optical axis of the lens barrel is applied to the focus operation ring 4. As a result, the collar 72 has a minute dimension as shown in FIG. 5A, that is, a lens barrel optical axis corresponding to the difference Δ between the diameter dimension of the shaft 73a of the screw 73 and the inner diameter dimension of the central shaft hole 72a of the collar 72. As shown in FIG. 5 (b), the flat surface 72b is surely brought into contact with one inner surface of the lower hole 71b of the connecting hole 71 as shown in FIG. The connecting force between the focus operation ring 4 and the focus cam ring 3 can be obtained by the frictional engagement force on the surface. At this time, it goes without saying that the lower surface of the head 73b of the screw 73 is in contact with the bottom surface of the upper hole 71a.

  In the first embodiment, the flat surface of the collar and the inner surface of the connecting hole are formed as surfaces parallel to the radial direction, but as shown in FIG. 6, the inner surface of the flat surface 72b of the collar 72A and the lower hole 71b of the connecting hole 71. May be tapered with a slight inclination from the outer diameter direction toward the inner diameter direction. In this case, the collar 72A is designed so that the upper surface of the collar 72A is lower than the bottom surface of the upper hole 71a of the connecting hole 71, and between the lower surface of the head 73b of the screw 73 and the upper surface of the collar 72. A spring washer 75 is inserted. In this configuration, even when a dimensional error such as a tolerance occurs between the opposing dimension in the radial direction of the two flat surfaces 72b of the collar 72A and the internal dimension of the lower hole 71b of the connecting hole 71 in the optical axis direction of the lens barrel. Both surfaces of the flat surface 72b and the inner surface of the lower hole 71b facing each other can be kept in close contact with each other, and the frictional engagement force between the collar 72A and the connecting hole 71 can be increased. At this time, it goes without saying that the lower surface of the head 73b of the screw 73 is in contact with the bottom surface of the upper hole 71a.

  In the first embodiment, the connection hole 71 is formed in a rectangular shape. However, as shown in FIG. 7, both end portions in the length direction may be formed in an arc shape as in the connection hole 71A. Or you may form a color | collar in the shape of a square cylinder of the side dimension suitable for the internal dimension of a connection hole.

  In the first embodiment, the focus lens is applied to a lens barrel that performs focus adjustment using a focus cam ring. However, in a lens barrel that performs focus adjustment using a focus screw ring, the focus operation ring and the focus screw ring are connected. The present invention can be applied to the structure.

1 is a partial cross-sectional view of a lens barrel of Embodiment 1 of the present invention. 1 is an exploded perspective view illustrating a schematic configuration of a main part of Example 1. FIG. It is a partial exploded perspective view of a focus adjustment mechanism. FIG. 4 is a plan sectional view and a longitudinal sectional view taken along line AA of the focus adjustment mechanism. It is the plane sectional view of the modification of a focus adjustment mechanism, and a BB line longitudinal sectional view. It is a top view of the modification of a connection hole. It is a longitudinal cross-sectional view of the modification of a focus adjustment mechanism.

Explanation of symbols

OS Lens barrel 1 Inner fixed ring 2 Outer fixed ring 3 Focus cam ring 4 Focus operation ring 5 Zoom cam ring 6 Zoom operation ring 7 Focus adjustment mechanism 71 Connection hole 71a Upper hole 71b Lower hole 72, 72A Color 72b Flat surface 73 Screw 73b Screw heads L1 to L5 First to fifth lenses F1 to F5 First to fifth lens frames R2 to R4 Roller Ox Lens barrel optical axis

Claims (7)

  A lens provided with a focus operation ring that is rotated around an optical axis, and a focus drive ring that is connected to the focus operation ring and is integrally rotated to adjust the focus by moving the focus lens in the optical axis direction. In the lens barrel, a connecting hole provided in an annular member disposed on the outer diameter side at a portion connecting the focus operation ring and the focus driving ring, and having a required length in the circumferential direction, A collar having an outer surface frictionally engaged with the inner surface of the connecting hole, and a screw inserted through the shaft hole of the collar from the outer diameter side and fastened to a ring member disposed on the inner diameter side. A lens barrel equipped with a characteristic focus adjustment mechanism.   2. The focus according to claim 1, wherein the connection hole is a long hole having a long side around the optical axis, and the collar and the screw are relatively movable in the long side direction inside the connection hole. A lens barrel with an adjustment mechanism.   2. The collar according to claim 1, wherein the collar is formed of a cylindrical body having a flat surface formed on at least a part of a side surface, and the flat surface is in contact with an inner surface extending in a circumferential direction of the connection hole. A lens barrel provided with the focus adjustment mechanism according to 2.   4. The focus adjustment mechanism according to claim 1, wherein a head portion of the screw is in contact with a surface of the outer diameter side ring member at a peripheral edge portion of the connection hole. Lens barrel.   5. The connecting hole according to claim 4, wherein the inner dimension of the upper hole in the thickness direction is larger than the inner dimension of the lower hole, and the head of the screw is in contact with the bottom of the upper hole. A lens barrel provided with the described focus adjustment mechanism.   A part of the focus operation ring is overlapped with a part of the focus drive ring from the outer diameter direction, the connection hole is provided in a part of the focus operation ring, and the screw is screwed to the outer peripheral surface of the focus drive ring. 6. A lens barrel provided with the focus adjusting mechanism according to claim 1, wherein the lens barrel is combined. 7. The focus adjustment mechanism according to claim 1, wherein the focus drive ring is a focus cam ring that is cam-engaged with a focus lens or a focus screw ring that is screw-coupled to the focus lens. Lens barrel.

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