JP4497599B2 - Lens barrel and imaging device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a lens barrel and an imaging apparatus that move a lens by a cam.
[0002]
[Prior art]
As a miniaturized camera, there is known a configuration having a retractable lens barrel that can accommodate a photographing lens in a camera body when photographing is not performed. Such a retractable lens barrel includes a so-called zoom lens barrel having a variable focal length composed of a plurality of lens groups. A configuration using a cam mechanism as a means for moving the plurality of lens groups of the zoom lens barrel along a predetermined zoom curve is known. That is, the lens group is moved to a predetermined position by driving the cam. In this configuration, by configuring the cam so as to be in a retracted state when not photographing, a lens barrel capable of moving the lens group from the storage position to the photographing position by a single cam curve can be realized.
[0003]
In addition, a method of using fitting of cam means for holding the lens group is known. For example, a lens group, a plurality of cam followers implanted at equal intervals around the lens group, a cylinder that covers these lens groups and has a cam groove corresponding to the plurality of cam followers, and a straight traveling means for moving the lens group straight By configuring the lens barrel, the guide bar and the bearing formed on the lens group are not required for holding the lens group, and a compact and easy-to-assemble barrel can be realized.
[0004]
Furthermore, there is known a configuration in which a lens barrier that protects the photographing lens is provided on the front surface of the photographing lens when photographing is not performed, and a camera that automatically opens and closes this lens barrier according to the photographing state of the camera is also known. There are known a configuration in which a motor dedicated to opening and closing is provided for opening and closing the lens barrier, and a configuration in which the lens barrier is opened and closed in conjunction with the retracting operation and the extending operation of the lens barrel.
[0005]
[Problems to be solved by the invention]
However, in order to obtain the required optical performance as a photographic lens, it is necessary to accurately hold each lens group at a predetermined position. When the lens group is held by the fitting of the cam means, the fitting play causes a decrease in the optical performance of the taking lens.Therefore, the cam means has a tight fitting setting with as little fitting play as possible. Required. In order to realize the tight fitting setting, it is necessary to reduce the manufacturing error of the cam and the cam follower, which causes an increase in the manufacturing cost of the parts.
[0006]
In the conventional example, the cross-sectional shape of the cam groove is the same from the storage position to the shootable position, and the lens group is driven by cam means having the same tight fitting setting as when shooting, even when shooting is not performed. . That is, although the lens group is not required to be held in precision, the fitting is tight, and a large load is applied to the lens barrel drive. In the case of the motor drive, unnecessarily large power is consumed. It was also a cause of advancing wear of cams and cam followers.
[0007]
In a lens barrel having a lens barrier that automatically opens and closes, the lens barrier is opened and closed in accordance with the retracting operation and the extending operation of the lens barrel. In the lens barrel having such a lens barrier, the load on the retracting or extending operation of the lens tube and the load on the opening / closing operation of the lens barrier are overlapped, so that the load on the motor temporarily becomes very large.
[0008]
Furthermore, in the case of a device that is often carried around and used like a small camera, it is a very important performance that it can be used for a long time without replacing or charging the battery. Also from the viewpoint of extending the driving time, reduction of the load for driving the lens barrel is required.
[0009]
SUMMARY OF THE INVENTION An object of the present invention is to provide a lens barrel and an imaging device that have a low load and a long service life.
[0010]
[Means for Solving the Problems]
A lens barrel according to the present invention, the cylindrical body that holds the lens and movable in the optical axis direction of the object side imaging plane side with respect to the barrel base by a cam follower fitted into the cam groove and the cam groove a lens barrel, the cam groove, a first size portion fitted to the cam follower in iMAGING region, in the non-imaging area, loosely fitting than fit in the shooting image region to said cam follower second size comprising a portion, wherein the cam groove in the second size portion, comprises a first oblique surface corresponding to the cam follower on the side of the imaging plane side, the cam follower on the side of the object side to comprising a loose second slope than, the lens barrel further the cylindrical body while resisting the urging force of the opening direction of the barrier by contacting the fixing projection and the barrier projection moves to the imaging plane side The cylinder is the subject It is biased in a direction to push the A lens barrier mechanism closing operation of the barrier, in case of transition from the imaging area to the non-IMAGING region, fitting the cam follower in the cam groove of the second size And a lens barrier mechanism that starts a closing operation of the barrier by the contact .
[0011]
An imaging apparatus according to the present invention includes the lens barrel described above.
[0012]
DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention applied to a camera having a zoom lens barrel whose lens barrier opens and closes in conjunction with a retracting operation of a lens group will be described in detail below with reference to the drawings.
[0013]
FIG. 1 is a sectional view of an embodiment of the present invention, and FIG. 2 is an exploded perspective view thereof. The lens barrel 10 of this embodiment includes six cylinders, that is, a cylinder 12, a moving cam cylinder 14, a rectilinear cylinder 16, a fixed cam cylinder 18, a drive ring 20, and a lens barrel base 22. The cylinder 12 on the most object side holds the first lens group 24 located on the most object side. The other lens groups are not shown. On the outer periphery of the cylindrical body 12, cam followers 12a are planted at intervals of 120 ° in the circumferential direction, and cylindrical rectilinear pins 12b are planted coaxially with the cam followers 12a.
[0014]
The moving cam cylinder 14 has a cam groove 14a that feeds the cylinder 12 to a predetermined position on the inner periphery. FIG. 3 is a development view of the inner surface of the movable cam cylinder 14. As will be described in detail later, the movable cam cylinder 14 is driven by the drive ring 20 to rotate around the optical axis, and moves in the optical axis direction along the cam groove 18a of the fixed cam cylinder 18 along with this rotation. FIG. 4 is a development view of the inner surface of the fixed cam cylinder 18.
[0015]
The shape of the cam groove 14a will be described. Three cam grooves 14a are formed in the same shape on the inner periphery of the movable cam cylinder 14 at equal intervals of 120 degrees corresponding to the cam follower 12a. The three cam followers 12a are respectively fitted in the separate cam grooves 14a, whereby the cylindrical body 12 is positioned three-dimensionally.
[0016]
The cam groove 14a has four parts, that is, an insertion cam 14a-1 into which the cam follower 12a is fitted before the cylindrical body 12 is assembled into the movable cam cylinder 14, and a retractable cam 14a-2 that holds the cylindrical body 12 in the retracted position. The feeding cam 14a-3 moves the cylindrical body 12 between the retracted position and the photographing position for photographing, and the photographing cam 14a-4 moves the zooming of the cylindrical body 12 within the photographing position.
[0017]
In order to move the cylinder 12 along the cam groove 14a, the rectilinear cylinder 16 is restricted only to advance straight in the optical axis direction without rotating the cylinder 12. The rectilinear cylinder 16 is rotatably fitted to the inner peripheral surface of the movable cam cylinder 14. The rectilinear cylinder 16 has an inner diameter larger than the outer diameter of the cylinder 12 and an outer diameter smaller than the inner diameter of the movable cam cylinder 14. A retaining pin 16a is planted on the outermost surface of the rectilinear cylinder 16 on the most object side, and is cut in the circumferential direction on the object side of the inner surface of the movable cam cylinder 14 so as to face the pin. A retaining groove 14b is formed. When the retaining pin 16 a enters the retaining groove 14 b, the rectilinear tube 16 is rotatable on the inner periphery of the movable cam tube 14 and moves in the optical axis direction integrally with the movable cam tube 14.
[0018]
Three rectilinear keys 16b are planted at the innermost position on the outer periphery of the rectilinear cylinder 16 at equal intervals of 120 degrees. By fitting the rectilinear key 16b into the rectilinear key groove 18b (see FIG. 4) extending in the optical axis direction of the fixed cam cylinder 18, the rectilinear cylinder 16 can move only in the optical axis direction without rotating.
[0019]
On the periphery of the rectilinear cylinder 16, rectilinear grooves 16 c extending in the optical axis direction are formed at three locations corresponding to the rectilinear pins 12 b of the cylinder 12. The rectilinear pin 12b of the cylindrical body 12 is fitted into the rectilinear groove 16c, whereby the cylindrical body 12 is restricted only to move in the optical axis direction. As a result, even if the movable cam cylinder 14 rotates, the cylinder 12 does not rotate but moves in the optical axis direction along the cam groove 14a.
[0020]
The lens barrel base 22 is a base of the lens barrel of this embodiment. The fixed cam cylinder 18 is fixed to the lens barrel base 22. Reference numeral 26 (FIG. 1) denotes an imaging surface.
[0021]
Three cam followers 14c are planted on the outer peripheral surface of the movable cam cylinder 14 at equal intervals of 120 degrees on the circumference centered on the optical axis. Three cam grooves 18a are formed in the same shape on the inner periphery of the fixed cam cylinder 18 at equal intervals of 120 degrees corresponding to the cam follower 14c. The movable cam cylinder 14 is positioned by fitting the three cam followers 14c into different cam grooves 18a.
[0022]
The fixed cylinder 18 enters the drive ring 20 almost closely. The drive ring 20 rotationally drives the movable cam cylinder 14 with the above-described configuration. On the inner peripheral surface of the drive ring 20, there are formed drive key grooves 20a extending in the optical axis direction at equal intervals of 120 degrees. Three drive pins 14d are planted on the outer peripheral surface of the movable cam cylinder 14 so as to be individually fitted in the drive key groove 20a. Due to the fitting of the drive key groove 20a and the drive pin 14d, the movable cam cylinder 14 rotates as the drive ring 20 rotates. The drive pin 14d passes through the fixed cam cylinder 18.
[0023]
The structure of the inner surface of the fixed cam cylinder 18 will be described in detail with reference to FIG. The cam groove 18a has four main parts, namely, an insertion cam 18a-1 for incorporating the movable cam cylinder 14 into the fixed cam cylinder 18, a retractable cam 18a-2 for holding the movable cam cylinder 14 in the retracted position, The feeding cam 18a-3 moves the cam barrel 14 between the retracted position and the shooting position for shooting, and the shooting cam 18a-4 moves the movable cam barrel 14 in the shooting position by a zoom operation. As described above, the cam follower 14c is fitted in the cam groove 18a, and the moving cam cylinder 14 is rotated by the drive ring 20, so that the moving cam cylinder 14 moves in the optical axis direction according to the cam groove 18a.
Reference numeral 18 c denotes a relief hole for the drive pin 14 d to penetrate the fixed cam cylinder 18.
[0024]
The overall operation of the lens barrel 10 of this embodiment will be described. Assuming that the lens barrel 10 is in the retracted state as an initial state, the operation of extending the lens barrel 10 from the retracted state to the photographing state will be described. The drive ring 20 is rotationally driven by a motor (not shown).
[0025]
In the retracted state, the cam follower 12a is fitted in the retracted cam 14a-2 of the cam groove 14a of the movable cam cylinder 14. The cam follower 14 c is fitted in the retracted cam 18 a-2 of the cam groove 18 a of the fixed cam cylinder 18. FIG. 2D shows the direction of rotation of the drive ring 20. The direction of the arrow is normal. In this state, when the drive ring 20 is rotated forward, the lens barrel 10 is drawn out so that the photographing can be performed.
[0026]
The rotation of the drive ring 20 is first transmitted to the moving cam cylinder 14. When the moving cam cylinder 14 rotates, the cam follower 14c moves from the retracted cam 18a-2 of the fixed cam cylinder 18 to the feeding cam 18a-3. At this time, since the cylinder 12 is not rotated by the rectilinear cylinder 16, the cam follower 12a is moved from the retracted cam 14a-2 of the cam groove 14a of the moving cam cylinder 14 to the feeding cam 14a-3 by the rotation of the moving cam cylinder 14.
[0027]
Thus, the movable cam cylinder 14 is extended by the rotation of the drive ring 20, and the cylinder 12 is extended with respect to the extended movable cam cylinder 14. When the drive ring 20 further rotates, the cylinder 12 and the movable cam cylinder 14 move onto the imaging cams 14a-4 and 18a-4, respectively, and the lens barrel 10 is ready for imaging. The absolute position of the cylinder 12 is the sum of the position of the cylinder 12 and the position of the movable cam cylinder 14.
[0028]
FIG. 5 shows a cam curve of the cam grooves 14a and 18a and a cam curve obtained by adding them. The horizontal axis shows the rotation angle of the drive ring 20 when the retracted position is 0 degree. The vertical axis shows the displacement from the retracted position. 30 indicates a cam curve of the cam groove 14a, and 32 indicates a cam curve of the cam groove 18a. Reference numeral 34 denotes a cam curve obtained as a result of adding the cam curve 30 and the cam curve 32. The composite cam curve 34 indicates the displacement of the cylindrical body 12 from the imaging surface 26.
[0029]
The lens barrier mechanism 40 of the lens barrel 10 will be described. FIG. 6 is an exploded perspective view of the lens barrier mechanism 40 in the opened state. The lens barrier mechanism 40 includes four plate-like barriers 42, 44, 46 and 48. The barriers 42 and 44 have the same shape and mainly shield the central part of the front surface of the lens. The barriers 46 and 48 have the same shape, and mainly shield the peripheral part of the front surface of the lens. These barriers 42, 44, 46, and 48 open and close the lens front surface by a rotating operation as will be described later. The shapes and operations of the barriers 42 and 44 are point symmetric about the optical axis, and the shapes and operations of the barriers 46 and 48 are point symmetric about the optical axis.
[0030]
Holes 42a and 44a serving as the rotation centers of the barriers 42 and 44 are formed at one end of the barriers 42 and 44, and shafts (not shown) of the cylindrical body 12 are fitted into the holes 42a and 44a, respectively. Similarly, holes 46a and 48a, which are the rotation centers of the barriers 46 and 48, are formed at one end of the barriers 46 and 48. The holes 46a and 48a have holes 12a and 44a, respectively. The same shaft fits. The barriers 46 and 48 rotate around the barriers 46a and 48a in conjunction with the barriers 42 and 44, respectively.
[0031]
Reference numeral 50 denotes a barrier drive plate that rotationally drives the barriers 42 and 44. The barrier drive plate 50 is fitted to the cylinder 12 and is rotatable about the optical axis. Notches 50a and 50b are formed on both sides of the barrier driving plate 50 which are 180 ° apart. The barrier drive pin 42b planted near the hole 42a of the barrier 42 intervenes in the notch 50a, and the barrier drive pin 44b planted near the hole 44a of the barrier 44 intervenes in the notch 50b. To do. When the barrier drive plate 50 rotates about the optical axis, the barriers 42 and 44 rotate about the holes 42a and 44a by the engagement of the notches 50a and 50b and the barrier drive pins 42b and 44b.
[0032]
The barrier drive plate 50 is urged in the B direction (FIG. 2) by a spring (not shown). Thereby, the barriers 42 and 44 are biased in the opening direction, and the barriers 46 and 48 are biased in the opening direction in conjunction with the barriers 42 and 44. When the lens barrel is ready for photographing, the barrier drive plate 50 can freely rotate, and the barriers 42, 44, 46, and 48 are always opened by a spring that biases the barrier drive plate 50 in the B direction. .
[0033]
A barrier protrusion 50c is formed on the imaging surface side of the barrier drive plate 50, and a fixed protrusion 52 is formed on the barrel base 22 corresponding to the barrier protrusion 50c. The slope 50d of the barrier protrusion 50c and the slope 52a of the fixed protrusion 52 face each other. The inclined surface 50d of the barrier protrusion 50 and the inclined surface 52a of the fixed protrusion 52 are not in contact when the lens barrel 10 is in the photographing state, but the cam follower 12a of the cylindrical body 12 is engaged with the pay-out cam 14a-3 and is shifted to the retracted state. Contact. As the cylindrical body 12 further moves in the retracting direction, the inclined surface 50d of the barrier protrusion 50 receives a force while sliding on the inclined surface 52a of the fixed protrusion 52, and the barrier driving plate 50 is moved in a direction opposite to the B direction in FIG. Rotate. As a result, the barriers 42 to 48 are gradually closed against the force of the spring. The barriers 42 to 48 are completely closed before the cam follower 12a of the cylindrical body 12 is completely moved to the retractable cam 14a-2.
[0034]
FIG. 7 is a cross-sectional view of the retractable cam 14a-2 and the photographing cam 14a-4 of the cam groove 14a. The cam follower 12a is fitted with a retractable cam 14a-2 and a photographing cam 14a-4. The camera is often carried in a retracted state, and the lens barrel 10 needs to be strong enough to resist vibration and impact when being carried. If the cam play in the retracted state is large, the lens barrel 10 may move violently due to vibration or impact, and the cam may be damaged. Therefore, the retractable cam 14a-2 is not as large as the photographing cam 14a-4. Must be tightly fitted. Further, in the shooting state, it is necessary to accurately position the cylindrical body 12 in order to exhibit required optical performance, and the cam is required to be tightly fitted and highly accurate.
[0035]
On the other hand, when the lens barrel is extended, it is not necessary to hold the cylindrical body 12, and it is not necessary to position it accurately. Therefore, it is possible to loosen the fitting of the cam, and it is preferable to loosen. FIG. 8 shows an example of a partial cross-sectional view of the feeding cam 14a-3 of the cam groove 14a. In this example, a loose fitting with the cam follower 12a is realized by opening the groove of the cam 14a-3 with respect to the cross-sectional shape of the cam follower 12a. By loosening the fitting in this manner, the load on the motor that drives the lens barrel can be reduced, power consumption can be suppressed, and wear of the cam follower and cam groove can be reduced. Furthermore, since the feeding cam 14a-3 with a loose fitting does not require high accuracy in the cam groove, the manufacturing cost of the movable cam cylinder 14 can be reduced.
[0036]
FIG. 9 shows another cross-sectional structure of a part of the feeding cam 14a-3 of the cam groove 14a. In this example, loose fitting with the cam follower 12a is realized by widening the groove of the cam 14a-3 with respect to the cross-sectional shape of the cam follower 12a. Thereby, the power saving effect as described above, the effect of reducing component wear, and the cost reduction effect are realized.
[0037]
The relationship between the cam fitting state of the cylinder 12 and the movable cam cylinder 14 and the operating state of the lens barrier will be described. When the cam follower 12a of the cylindrical body 12 is fitted to the photographing cam 14a-4, as shown in FIG. 10, the barrier protrusion 50c and the fixed protrusion 52 are greatly separated. As the lens barrel is retracted, the cam follower 12a of the cylinder 12 comes into engagement with the pay-out cam 14a-3, but until the cylinder 12 reaches the point P in FIG. 3, the barrier is similar to that shown in FIG. The protrusion 50c and the fixed protrusion 52 are separated from each other. Immediately before the point P, the barrier protrusion 50c and the fixed protrusion 52 start to contact each other as shown in FIG. Thereafter, as the lens barrel is retracted, the barrier driving plate 50 is rotated while the inclined surface 50d of the barrier protrusion 50c and the inclined surface 52a of the fixed protrusion 52 are rubbed as shown in FIG. FIG. 13 shows a contact state between the barrier protrusion 50c and the fixed protrusion 52 when the lens barrel is completely retracted.
[0038]
The cylindrical body 12 does not rattle as described above when the cam follower 12a is engaged with the photographing cam 14a-4. When the barrier protrusion 50c and the fixed protrusion 52 are in contact with each other, an urging force acts on the cylindrical body 12 in the optical axis direction, and rattling is suppressed. Accordingly, since the fitting of the cylindrical body 12 changes to a loose state after the barrier projection 50c and the fixed projection 52 are brought into contact with each other, the cylinder 12 will never rattle no matter which cam is fitted.
[0039]
The feeding cam 14a-3 having the cross section shown in FIG. 8 or FIG. 9 and the cams 14a-2 and 14a-4 having the cross section shown in FIG. 7 are connected with their shapes gradually changed as shown in FIG. Thereby, the cam follower 12a can smoothly transition between tight fitting and loose fitting without being caught in the middle.
[0040]
The cylindrical body 12 is urged in a direction to push out toward the subject side by the contact between the slope 50d of the barrier projection 50c and the slope 52a of the fixed projection 52. Even when the fitting of the cam is loosened by designing the inclined surface 50d of the barrier protrusion 50c and the inclined surface 52a of the fixed protrusion 52 immediately before the gentle change in the shape of the feeding cam 14a-3, the lens barrel Is not rattling.
[0041]
As described above, the lens barrier mechanism 40 is closed when the lens barrel is retracted. At this time, the lens barrier mechanism 40 resists the biasing force of the spring, so that a large load is applied to the motor. However, as in this embodiment, the load of the lens barrel drive can be distributed by loosening the fitting of the cam at the lens barrel feeding cam 14a-3. As a result, the load peak applied to the motor can be significantly reduced, and the motor drive voltage can be reduced. Since the minimum drive voltage of the camera body can be set low due to a decrease in the drive voltage of the motor, the drive time of the camera can be extended.
[0042]
Even if the lens barrel moves vigorously due to vibration or impact, the retractable cam 14a-2 can be a loosely fitted cam if the strength is sufficient to prevent the cam from being damaged. In this way, wear and manufacturing costs can be further reduced.
[0043]
【The invention's effect】
As can be easily understood from the above description, according to the present invention, the cam can be partially loosened to reduce the power consumption of the camera and reduce the cam wear and manufacturing costs.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an embodiment of the present invention.
FIG. 2 is an exploded perspective view of the present embodiment.
FIG. 3 is a diagram of a movable cam cylinder 14 developed on a plane and viewed from the inside.
FIG. 4 is a view of the fixed cam cylinder 18 developed on a plane and viewed from the inside.
FIG. 5 is a diagram showing cam curves of the cam groove 14a and the cam groove 18a and their combined cam curves.
6 is an exploded perspective view of the lens barrier mechanism 40 in a state where the barrier is open. FIG.
7 is a cross-sectional view of a retractable cam 14a-2 and a photographing cam 14a-4 in the cam groove 14a. FIG.
FIG. 8 is a sectional view of a feeding cam 14a-3 of the cam groove 14a.
FIG. 9 is a cross-sectional view of another configuration of the feeding cam 14a-3 of the cam groove 14a.
FIG. 10 is a diagram showing a positional relationship between the barrier protrusion 50 and the fixed protrusion 52 when the cam follower 12a is fitted to the photographing cam 14a-4.
11 is a diagram showing a positional relationship between the barrier protrusion 50 and the fixed protrusion 52 when the cam follower 12a reaches the point P in FIG.
12 is a view showing the positional relationship between the barrier protrusion 50 and the fixed protrusion 52 when the lens barrel is further retracted than in FIG.
FIG. 13 is a diagram showing a positional relationship between the barrier protrusion 50 and the fixed protrusion 52 when fully retracted.
[Explanation of symbols]
10: Lens barrel 12: Tube 12a: Cam follower 12b: Straight advance pin 14: Moving cam cylinder 14a: Cam groove 14a-1: Insertion cam 14a-2: Retracting cam 14a-3: Feeding cam 14a-4: Shooting cam 14b : Retaining groove 14c: cam follower 14d: drive pin 16: rectilinear cylinder 16a: retaining pin 16b: rectilinear key 16c: rectilinear groove 18: fixed cam cylinder 18a: cam groove 18a-1: insertion cam 18a-2: retractable cam 18a -3: Feeding cam 18a-4: Shooting cam 18b: Straight key groove 18c: Relief hole 20: Drive ring 20a: Drive key groove 22: Lens barrel base 24: First lens group 26: Imaging surface 30: Cam groove 14a Cam curve 32: Cam curve 34 of cam groove 18a: Composite cam curve 40: Lens barrier mechanisms 42, 44, 46, 48: Barriers 42a, 44a, 46a, 4 a: hole 42b, 44b: barrier drive pin 50: barrier driver plate 50a, 50b: notch 50c: barrier projection 50d: slope 52 of the barrier projection 50c: fixing protrusion 52a: inclined surface of the fixing protrusion 52

Claims (2)

A cylindrical body that holds the lens, a lens barrel and movable in the direction of the optical axis of the object-side imaging plane side with respect to the barrel base by a cam follower fitted into the cam groove and the cam groove,
The cam groove includes a first sized portion to fit the cam follower in IMAGING region, in the non-imaging area, a second size portion which loosely fits than fit in the shooting image region to said cam follower Comprising
Said cam groove in said second size portion, comprises a first oblique surface corresponding to the cam follower on the side of the imaging plane side, comprises a loose second slope than the cam follower on the side of the object side,
The lens barrel is further attached in a direction in which the cylindrical body pushes out toward the subject while resisting the urging force in the barrier opening direction by moving the cylindrical body toward the imaging surface and contacting the barrier protrusion and the fixed protrusion. are energized by a lens barrier mechanism which closes operating the barrier, in case of transition from the imaging region in the non-shooting image area, when said cam follower is fitted in the cam groove of the second size A lens barrel comprising a lens barrier mechanism for starting a closing operation of the barrier by the contact .   An imaging apparatus comprising the lens barrel according to claim 1.

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