JP2018180357A - Lens barrel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lens barrel in which loosening occurring during movement thereof is suppressed, and which therefore materializes reduction of degradation in optical performance thereof.SOLUTION: A lens barrel 100 includes a movable lens barrel 103, a zoom differential lens barrel 105, a movable lens barrel 106, a cam barrel 131, a main guide shaft 151, and a sub guide shaft 152. The zoom differential lens barrel 105 has a cam follower part 105c disposed so as to be engaged with a cam groove 131c of the cam barrel 131, and also has a main guide shaft engagement part 105a engaged with the main guide shaft 151, and a sub guide shaft engagement part 105b engaged with the sub guide shaft 152. The zoom differential lens barrel 105 moves by rotation of the cam barrel 131 to change the position of the lens barrel 105 relative to the movable lens barrels 103 and 106. The main guide shaft 151 and the sub guide shaft 152 are disposed at positions where they face each other across an optical axis AX, and the cam follower part 105c is disposed in the vicinity of the sub guide shaft engagement part 105b.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a lens barrel, and, for example, to a lens barrel having a linear movement mechanism by a guide shaft and a relative movement mechanism of a lens group by rotation of a cam barrel.

  In recent years, high optical performance is required for an imaging lens of a digital camera. In particular, as interchangeable lenses of interchangeable lens camera systems are required to have high optical performance, in the case of zoom lenses, the number of lens groups moved for zooming is increasing to achieve high optical performance. .

  For example, Patent Document 1 proposes an example of a lens barrel having a plurality of movable lens barrels for zooming movement of a plurality of lens groups. In the lens barrel described in Patent Document 1, the movable barrel has a main guide shaft engagement portion, a sub guide shaft engagement portion, and a cam follower portion disposed in the vicinity of the main guide shaft engagement portion. The structure in which the cam follower portion engages with the cam groove allows the linear movement with the rotation of the cam cylinder.

Japanese Patent Application Laid-Open No. 2006-053496

  However, in the configuration like the lens barrel described in Patent Document 1, since the cam follower portion is disposed in the vicinity of the main guide shaft engaging portion, the inclination of the movable lens barrel is due to the rattling of the main guide shaft engaging portion. It will be determined by the amount and the fitting length of the main guide shaft engaging portion. Since there is a limit to reduce the amount of rattling of the engaging portion due to part accuracy, it is necessary to secure the fitting length of the main guide shaft engaging portion within the possible range in order to suppress inclination rattling of the movable barrel However, there is a limit to the physical arrangement.

  The present invention has been made in view of such a situation, and it is an object of the present invention to provide a lens barrel in which deterioration of optical performance is reduced by suppressing rattling generated during movement of the barrel.

In order to achieve the above object, the lens barrel of the first invention is a lens barrel having an imaging lens consisting of a plurality of lens groups and having a plurality of lens barrels for holding the lens groups,
A cam cylinder having a cam groove,
At least one first barrel arranged as one of the barrels;
A second barrel disposed as one of the barrels and movable in the optical axis direction of the imaging lens so that the relative position to the first barrel changes;
A cam follower portion provided in the second lens barrel so as to engage with the cam groove and capable of moving the second lens barrel in the optical axis direction by rotation of the cam barrel;
A main guide shaft which is held by the first lens barrel and guides movement of the second lens barrel while suppressing inclination from a direction perpendicular to the optical axis;
And a secondary guide shaft which is held by the first barrel and guides movement of the second barrel while suppressing rotation of the second barrel centered on the main guide shaft.
The second lens barrel has a main guide shaft engaging portion engaged with the main guide shaft, and a sub guide shaft engaging portion engaged with the sub guide shaft;
The main guide shaft and the sub guide shaft are disposed at positions facing each other across the optical axis,
The cam follower portion is disposed in the vicinity of the auxiliary guide shaft engaging portion.

  The lens barrel according to a second aspect of the present invention is the lens barrel according to the first aspect, wherein a straight line passing the main guide shaft and the cam follower portion in a plane perpendicular to the optical axis is the main guide shaft and the sub guide shaft In an angle range of ± 20 ° based on a straight line passing through

  A lens barrel according to a third aspect of the present invention is the lens barrel according to the first or second aspect, wherein the main guide shaft is engaged with the main guide shaft engaging portion in a plane perpendicular to the optical axis. A linear distance from a center to a center of the cam follower portion at a portion engaged with the cam groove is longer than a fitting length of the main guide shaft to the main guide shaft engaging portion. .

  A lens barrel according to a fourth aspect of the present invention is the lens barrel according to any one of the first to third aspects, wherein the lens barrel is an extension of a straight line connecting the main guide axis and the optical axis in a plane perpendicular to the optical axis. A secondary guide shaft is arranged.

  According to the present invention, the main guide shaft and the sub guide shaft are disposed at opposite positions with the optical axis interposed therebetween, and the cam follower portion is disposed in the vicinity of the sub guide shaft engaging portion. The amount of tilt rattling caused by the rattling between the head and the cam groove is reduced. Therefore, it is possible to reduce the deterioration of the optical performance by suppressing the rattling that occurs when the lens barrel moves. For example, it is possible to obtain high optical performance even with a lens replacement zoom lens that has a large number of lens units moving in zoom.

Sectional drawing which shows schematic structure in the wide-angle end of the embodiment of a lens barrel, and a telephoto end. Sectional drawing which shows zoom differential lens barrel periphery structure in embodiment of a lens barrel. FIG. 5 is a plan view showing a zoom differential lens barrel peripheral structure from an image forming side. FIG. 7 is a perspective view showing a zoom differential lens barrel peripheral structure from an image forming side. FIG. 2 is a perspective view showing an embodiment of a lens barrel from the outside of a straight advance barrel. FIG. 2 is a perspective view showing an embodiment of a lens barrel from the outside of a cam barrel.

  Hereinafter, a lens barrel and the like according to the present invention will be described with reference to the drawings. FIG. 1 shows a schematic cross-sectional structure of the lens barrel 100 in each zoom state at the wide-angle end (W) and the telephoto end (T). A lens mount 111 is provided on the image forming side of the lens barrel 100. The lens barrel 100 is mechanically and electrically coupled to the camera body BD incorporating the imaging element SR via the lens mount 111. That is, the lens barrel 100 is detachable from the camera body BD, and a lens interchangeable type camera system is configured by a combination of the lens barrel 100 and the camera body BD.

  The lens barrel 100 has a zoom lens ZL consisting of five lens groups 1 to 5 as an imaging lens, and each of the lens groups 1 to 5 is composed of one or more lenses. The lens unit 1 is held by the movable barrel 101, and moves in the direction of the optical axis AX of the zoom lens ZL when zooming. The lens groups 2 to 5 are held by the movable barrel 103 and the movable barrel 106, and move in the direction of the optical axis AX along a locus independent of the lens group 1 at the time of zooming. The movable lens barrel 103 and the movable lens barrel 106 are fixed by screwing, and the lens group 3 and the lens group 5 zoom move integrally. The movable lens barrel 103 also holds a motor unit (not shown) for moving the movable lens barrel 102 in the direction of the optical axis AX, a diaphragm unit 130 constituting an aperture stop, and the like.

  The lens group 2 is a focus group, and is held by the movable lens barrel 102 in a form subordinate to the lens groups 3 to 5. In addition, the lens group 2 is driven by the motor unit to move relative to the lens groups 3 to 5 during focusing and zooming to maintain the focusing performance and the optical performance for each zoom position. Have. The motor unit is composed of a motor head which generates a rotational force as a drive source, and a lead screw which is rotationally driven by the rotational force.

  The movable barrel 102 is disposed on the subject side of the diaphragm unit 130, and is movable in the direction of the optical axis AX so that the position relative to the movable barrel 103 is changed. The diaphragm unit 130 has a structure in which the aperture diameter is electrically variable, and is disposed closer to the image forming side (i.e., the imaging element SR side) than the movable barrel 102, and the movable barrel 103 It is held on the subject side. The aperture unit 130 is also screwed to the movable lens barrel 103.

  The lens group 4 is held by the zoom differential lens barrel 105. Further, the main guide shaft 151 and the sub guide shaft 152 are disposed at opposite positions across the optical axis AX, and the movable lens barrels 103 and 106 support the main guide shaft 151 and the sub guide shaft 152 at both ends. ing. The zoom differential lens barrel 105 has a main guide shaft engaging portion 105 a engaged with the main guide shaft 151 and a sub guide shaft engaging portion 105 b engaged with the sub guide shaft 152. It is held by the movable lens barrels 103 and 106 via the shaft 151 and the auxiliary guide shaft 152.

  The main guide shaft 151 is held by the movable lens barrels 103 and 106, and guides the movement of the zoom differential lens barrel 105 while suppressing the inclination from the vertical direction with respect to the optical axis AX. On the other hand, the auxiliary guide shaft 152 is held by the movable lens barrels 103 and 106, and the movement of the zoom differential lens barrel 105 while suppressing the rotation of the zoom differential lens barrel 105 with the main guide shaft 151 as an axis. Guide. Therefore, the zoom differential barrel 105 is movable in the direction of the optical axis AX such that the relative position with respect to the movable barrel 103 and the movable barrel 106 changes.

  Around the movable lens barrels 101 and 103, etc., there are provided a rectilinear barrel 132 having a rectilinear groove 132a (FIG. 5) and a rectilinear groove 132b, and a cam barrel 131 having cam grooves 131a, 131b and 131c. . In addition, the movable barrel 101 has a cam follower portion (not shown) arranged in three equal circumferences, and similarly, a cam follower portion arranged in three equal circumferences. It has 103a. The cam follower portion of the movable barrel 101 is engaged with the rectilinear groove 132a and the cam groove 131a, and the cam follower portion 103a of the movable barrel 103 is engaged with the rectilinear groove 132b and the cam groove 131b. The cylinder 131 is diametrically fitted to the straight advancing cylinder 132.

  Therefore, when the cam barrel 131 is rotated about the optical axis AX, the cam follower portions 103a and the like of the movable barrels 101 and 103 move along the cam grooves 131a and 131b, whereby zooming is performed. In addition, the zoom differential lens barrel 105 has a cam follower portion 105c, and the cam follower portion 105c is engaged with the cam groove 131c of the cam barrel 131, and the lens group 3 is rotated by the rotation of the cam barrel 131 described above. And can be moved relative to the lens group 5.

  A focus operation ring 108 and a zoom operation ring 109 are provided around the linear movement cylinder 132. The focus operation ring 108 is rotatable relative to the rectilinear barrel 132 about the optical axis AX. When the signal of the photo sensor (not shown) is detected by the rotation of the focus operation ring 108, the lens unit 2 as the focus group can be driven to focus by the motor unit. The zoom operation ring 109 is rotatable relative to the rectilinear barrel 132 about the optical axis AX. The zoom operation ring 109 is configured to be rotationally interlocked with the cam cylinder 131 by a zoom interlocking pin (not shown), and the cam cylinder 131 is rotated by the rotation operation of the zoom operation ring 109 to enable zoom operation. .

  A front exterior lens barrel 107 a is provided on the object side of the focus operation ring 108, and a rear exterior lens barrel 107 b is provided on the image formation side of the zoom operation ring 109. The exterior lens barrels 107a and 107b function as retainers for the focus operation ring 108 and the zoom operation ring 109, respectively, and form the exterior of the lens barrel 100.

  Next, the detailed configuration of the lens barrel 100, in particular, the configuration around the zoom differential barrel 105 will be described. FIG. 2 shows a schematic cross-sectional structure around the zoom differential lens barrel 105 in the lens barrel 100 at the wide angle end (W), and FIG. 3 and FIG. 4 show an external appearance structure around the zoom differential lens barrel 105. FIG. 3 shows an appearance of the structure around the zoom differential lens barrel 105 as viewed from the image forming side along the optical axis AX, and FIG. 4 shows the structure around the zoom differential lens barrel 105 obliquely from the image forming side It shows the appearance seen from the point of view. 5 and 6 show the external appearance of the lens barrel 100 as viewed obliquely from above on the image forming side. FIG. 5 shows the external appearance seen from the outside of the rectilinear advance barrel 132, and FIG. 6 shows the external appearance seen from the outside of the cam cylinder 131. As shown in FIG. The movable lens barrel 106 and the like appearing in FIGS. 5 and 6 are not shown in FIGS. 3 and 4.

  As described above, the zoom differential lens barrel 105 has the main guide shaft engaging portion 105a and the sub guide shaft engaging portion 105b (FIGS. 1 to 4), and the main guide shaft 151 and the sub guide shaft 152 respectively. It is possible to move in a straight line by engaging with. The main guide shaft engaging portion 105a has a fitting length in the direction of the optical axis AX, and the inclination of the zoom differential lens barrel 105 is set by setting the radial rattle with the main guide shaft 151 small. To suppress. That is, the proper orientation of the zoom differential lens barrel 105 is maintained by the main guide shaft 151 and the main guide shaft engaging portion 105a. On the other hand, the auxiliary guide shaft 152 and the auxiliary guide shaft engaging portion 105 b suppress the rotation of the zoom differential lens barrel 105 around the main guide shaft 151. That is, the rotation of the zoom differential lens barrel 105 is prevented by the auxiliary guide shaft 152 and the auxiliary guide shaft engaging portion 105 b. Of the two ends of the main guide shaft 151 and the sub guide shaft 152, the end on the subject side is supported by the movable lens barrel 103, and the end on the image forming side is supported by the movable lens barrel 106.

  The zoom differential lens barrel 105 has a cam follower portion 105c formed separately or integrally in the vicinity of the auxiliary guide shaft engaging portion 105b. The cam follower portion 105 c is provided in the zoom differential lens barrel 105 so as to engage with the cam groove 131 c formed in the cam barrel 131, and the light of the zoom differential lens barrel 105 is rotated by rotation of the cam barrel 131. Enables movement in the direction of axis AX. Therefore, the lens group 4 held by the zoom differential lens barrel 105 can move relative to the lens group 3 and the lens group 5.

  As described above, the main guide shaft 151 and the sub guide shaft 152 are disposed at opposite positions across the optical axis AX, and the cam follower portion 105c is disposed in the vicinity of the sub guide shaft engagement portion 105b. . When the inclination of the center of the fitting length (FIG. 2) X due to the fitting play between the main guide shaft 151 and the main guide shaft engaging portion 105a is taken into consideration, the cam follower portion 105c is arranged near the sub guide shaft 152 In this case, the center of the fitting portion of the main guide shaft 151 generated by the rattling (follower in the radial direction of the follower) between the cam follower portion 105c and the cam groove 131c than in the case where the main guide shaft 151 is disposed. Since it is possible to reduce the amount of inclination play, it is advantageous in suppressing the amount of inclination play.

  In addition, the cam follower portion 105c often sets the play between the cam groove 131c and the cam groove 131c smaller by selecting the follower diameter at the time of assembly. Therefore, particularly when the cam follower portion 105c is configured separately, it is preferable to set the amount of rattling with the cam groove 131c small, whereby the rattling reduction effect can be further increased.

  As shown in FIG. 2, the cam groove 131c (FIG. 1, FIG. 6) from the center of the main guide shaft 151 at a portion engaged with the main guide shaft engaging portion 105a in a plane perpendicular to the optical axis AX. The linear distance Y to the center of the cam follower portion 105c at the portion engaged with the main guide shaft 151 is set longer than the fitting length X of the main guide shaft 151 with respect to the main guide shaft engaging portion 105a (X Y). For this reason, the inclination of the zoom differential barrel 105 can be suppressed without increasing the fitting length X more than necessary.

Here, specifically, assuming that the fitting play amount between the main guide shaft engaging portion 105a and the main guide shaft 151 is Δh1, the inclination θ1 generated in the zoom differential lens barrel 105 is expressed by the following equation (A) Ru.
θ1 = tan ⁻¹ (Δh1 / X) (A)
Similarly, when the amount of backlash between the cam follower portion 105c and the cam groove 131c is Δh2, the inclination θ2 generated in the zoom differential lens barrel 105 is expressed by the following formula (B).
θ 2 = tan ⁻¹ (Δh 2 / Y) (B)

  Here, when Δh1 and Δh2 are substantially equal, θ1> θ2 from the relationship of X <Y, and the inclination generated in the zoom differential lens barrel 105 is θ2. Therefore, by setting the linear distance Y to be longer than the fitting length X, it is possible to suppress the inclination generated in the zoom differential lens barrel 105. Furthermore, as shown in FIG. 3, in a plane perpendicular to the optical axis AX, a longer straight line is obtained by arranging the sub guide shaft 152 on the extension of the straight line LN connecting the main guide shaft 151 and the optical axis AX. The distance Y can be secured.

  As in the embodiment described above, in a lens barrel having an imaging lens consisting of a plurality of lens groups and having a plurality of barrels holding the lens groups, for example, the main guide axis and the sub guide axis When the zoom mechanism is constituted by the straight movement mechanism and the relative moving mechanism of the zoom group by the rotation of the cam barrel, the configuration around the zoom mechanism becomes important in suppressing the backlash of the movable barrel. Since this is not limited to the zoom mechanism, here, the movable barrels 103 and 106 are set as the first barrel, the zoom differential barrel 105 is set as the second barrel, and the cam follower portion is provided in the second barrel. A second lens barrel can be moved in the optical axis direction so that the relative position to the first lens barrel changes. If the arrangement of the cam follower portion is devised in this configuration, it is possible to suppress the inclination play of the second lens barrel.

  As an example of the arrangement of the cam follower portion for suppressing the inclination looseness of the second lens barrel, as in the lens barrel 100, the main guide shaft and the sub guide shaft are disposed at a position facing each other across the optical axis. The cam follower portion may be disposed in the vicinity of the auxiliary guide shaft engaging portion. In this configuration, the amount of looseness in the center of the fitting portion of the main guide shaft caused by the looseness between the cam follower portion and the cam groove than in the configuration in which the cam follower portion is disposed in the vicinity of the main guide shaft engaging portion. Can be reduced, which is advantageous in suppressing the amount of backlash. In addition, since the cam follower portion can set the backlash with the cam groove smaller by selecting the follower diameter at the time of assembly, it is possible to further increase the backlash reduction effect.

  Therefore, according to the above configuration, the main guide shaft and the sub guide shaft are disposed at opposing positions across the optical axis, and the cam follower portion is disposed in the vicinity of the sub guide shaft engaging portion, The amount of tilt play produced by play between the cam follower portion and the cam groove is reduced. Therefore, it is possible to reduce the deterioration of the optical performance by suppressing the rattling that occurs when the lens barrel moves. For example, it is possible to obtain high optical performance even with a lens replacement zoom lens that has a large number of lens units moving in zoom.

  In the embodiment, an angle of a straight line passing through the main guide shaft 151 and the cam follower portion 105c in a plane perpendicular to the optical axis AX as the vicinity of the sub guide shaft engaging portion 105b at the time of disposing the cam follower portion 105c. The range is assumed to be ± 20 ° based on a straight line LN (FIG. 3) passing through the main guide shaft 151 and the sub guide shaft 152. If this condition is satisfied, rattling that occurs when the lens barrel is moved can be effectively suppressed. Therefore, in a plane perpendicular to the optical axis, a straight line passing through the main guide shaft and the cam follower portion is within an angular range of ± 20 ° based on a straight line passing through the main guide shaft and the sub guide shaft. Is preferred.

  A portion engaged with the cam groove from a center of the main guide shaft at a portion engaged with the main guide shaft engaging portion in a plane perpendicular to the optical axis as in the embodiment It is preferable that the linear distance Y to the center of the cam follower portion in the above is longer than the fitting length X of the main guide shaft with respect to the main guide shaft engaging portion (X <Y). According to this configuration, the inclination due to the backlash in the cam follower portion and the cam groove is smaller than the inclination due to the backlash in the main guide shaft and the main guide shaft engaging portion (θ1> θ2). Can be effectively reduced.

  In the embodiment, the optical axis AX is located on a straight line LN (FIG. 3) passing through the main guide shaft 151 and the sub guide shaft 152 in a plane perpendicular to the optical axis AX. Thus, if the sub-guide axis is disposed on an extension of a straight line connecting the main guide axis and the optical axis in a plane perpendicular to the optical axis, the linear distance Y can be set long. It is possible to effectively reduce the inclination generated in the two lens barrels.

1 to 5 lens group 100 lens barrel 101 moving lens barrel 102 moving lens barrel 103 moving lens barrel (first lens barrel)
103a Cam follower portion 105 zoom differential lens barrel (second lens barrel)
105a main guide shaft engaging portion 105b secondary guide shaft engaging portion 105c cam follower portion 106 moving lens barrel (first lens barrel)
107a front exterior lens barrel 107b rear exterior lens barrel 108 focus operation ring 109 zoom operation ring 111 lens mount 130 aperture unit 131 cam cylinder 131a, 131b, 131c cam groove 132 linear movement cylinder 132a, 132b straight groove 151 main guide shaft 152 secondary guide Axis ZL zoom lens (imaging lens)
SR image sensor BD camera body AX light axis

Claims (4)

A lens barrel having an imaging lens composed of a plurality of lens groups, and having a plurality of barrels for holding the lens groups,
A cam cylinder having a cam groove,
At least one first barrel arranged as one of the barrels;
A second barrel disposed as one of the barrels and movable in the optical axis direction of the imaging lens so that the relative position to the first barrel changes;
A cam follower portion provided in the second lens barrel so as to engage with the cam groove and capable of moving the second lens barrel in the optical axis direction by rotation of the cam barrel;
A main guide shaft which is held by the first lens barrel and guides movement of the second lens barrel while suppressing inclination from a direction perpendicular to the optical axis;
And a secondary guide shaft which is held by the first barrel and guides movement of the second barrel while suppressing rotation of the second barrel centered on the main guide shaft.
The second lens barrel has a main guide shaft engaging portion engaged with the main guide shaft, and a sub guide shaft engaging portion engaged with the sub guide shaft;
The main guide shaft and the sub guide shaft are disposed at positions facing each other across the optical axis,
A lens barrel characterized in that the cam follower portion is disposed in the vicinity of the auxiliary guide shaft engaging portion.   In a plane perpendicular to the optical axis, a straight line passing through the main guide shaft and the cam follower portion is within an angle range of ± 20 ° based on a straight line passing through the main guide shaft and the sub guide shaft The lens barrel according to claim 1, characterized in that   The center of the cam follower portion at the portion engaged with the cam groove from the center of the main guide shaft at the portion engaged with the main guide shaft engaging portion in a plane perpendicular to the optical axis The lens barrel according to claim 1 or 2, wherein a linear distance up to the point is longer than the fitting length of the main guide shaft with respect to the main guide shaft engaging portion.   The auxiliary guide shaft is disposed on an extension of a straight line connecting the main guide axis and the optical axis in a plane perpendicular to the optical axis. Lens barrel described.

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