JP2011128485A - Lens barrel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens barrel whose outer diameter is not made larger, even when a movable barrel is driven by a linear actuator. <P>SOLUTION: The lens barrel has a fixed barrel, which is fixed, and at least one movable barrel, which can be moved in an optical axial direction, wherein the lens barrel is configured such that the movable barrel is extended to the side of an object from the fixed barrel in photographing and the movable barrel is stored in the fixed barrel in non-photographing. In the lens barrel, a drive shaft integrated with an electromechanical transducer is frictionally engaged with the movable barrel, the drive shaft is displaced by the expansion and contraction of the electromechanical transducer, to drive the movable barrel along the drive shaft, and the drive shaft is arranged more inside than the inner circumferential surface of the movable barrel. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a lens barrel that drives a movable cylinder holding a lens or the like in an optical axis direction by an electromechanical conversion element.

  Linear actuators using electromechanical transducer elements such as piezoelectric elements (piezo elements) that expand and contract when voltage is applied are known.

  The configuration and operation of this linear actuator will be described with reference to FIGS. FIG. 1 is a front view of the linear actuator, FIG. 2 is a perspective view of the linear actuator, and FIG. 3 is a diagram for explaining an operation principle of the linear actuator.

  As shown in FIG. 1, the linear actuator 10 mainly includes an electromechanical conversion element 11, a drive shaft 12, a holding member 13, a flexible printed board 14, and the like, and is configured in a small size.

  The electromechanical conversion element 11 is a piezoelectric element in which a plurality of piezoelectric materials made of piezoelectric ceramic and internal electrodes are alternately stacked. When a voltage is applied, the piezoelectric material is displaced in the thickness direction, so that the electromechanical conversion element 11 expands and contracts.

  The drive shaft 12 is a rod-shaped member joined to one end of the electromechanical conversion element 11 in the expansion / contraction direction with an adhesive S1, and is formed of a material having good slipperiness and high surface hardness.

  The holding member 13 is joined to the other end in the expansion / contraction direction of the electromechanical conversion element 11 by an adhesive S2, holds the electromechanical conversion element 11 and the drive shaft 12 in a cantilever, and is formed of a metal material having a large specific gravity. . The adhesive S2 is insulative so that the electromechanical conversion element 11 and the holding member 13 do not conduct.

  The flexible printed circuit board 14 is joined to the electromechanical conversion element 11 by the conductive adhesive S <b> 3 and supplies power to the electromechanical conversion element 11.

  2A is a perspective view of the linear actuator before the movable member and the like are assembled, and FIG. 2B is a perspective view of the linear actuator after the movable member and the like are assembled.

  The movable member 15 is joined to or integrally formed with a member to be driven by a linear actuator, and the member to be driven is, for example, a lens frame that holds a lens. A V-groove 15 a is formed in the movable member 15 and faces the drive shaft 12. A clamping member 16 having a V-groove 16 a facing the drive shaft 12 is also arranged on the opposite side of the drive shaft 12. Then, a U-shaped plate spring 17 is mounted from the lateral direction of the movable member 15 and the sandwiching member 16 so that the movable member 15 and the sandwiching member 16 tightly attach the drive shaft 12 with a predetermined frictional force. As a result, the movable member 15 comes into pressure contact with the drive shaft 12.

  Various configurations are possible for sliding the movable member 15 relative to the drive shaft 12, and a tension spring or a compression spring is used between the movable member 15 and the holding member 16 without using the leaf spring 17. The movable member 15 may be in pressure contact with the drive shaft 12.

  The operation principle of the linear actuator configured as described above will be described with reference to FIG. A pulse voltage having a sawtooth waveform as shown in FIG. 3B is continuously applied to the electromechanical transducer 11 shown in FIG. 3A1 through the flexible printed board 14 shown in FIGS. As a result, the electromechanical transducer 11 expands and contracts, and at the same time, the drive shaft 12 also vibrates in the axial direction. As shown in FIG. 3 (A2), the electromechanical conversion element 11 expands relatively slowly at the gradual rise U of the pulse voltage. Accordingly, the drive shaft 12 is extended in a direction away from the holding member 13 (α direction), and accordingly, the movable member 15 that is in pressure contact with the drive shaft 12 slides in the same direction. On the other hand, at the rapid fall D of the pulse voltage, the electromechanical transducer 11 contracts rapidly and returns to the initial length. At this time, as shown in FIG. 3 (A3), the drive shaft 12 also rapidly returns in the direction toward the holding member 13 (β direction), but the movable member 15 stays at that position due to inertia or slightly holds the holding member 13. Slide in the direction of. Therefore, by continuously applying such a pulse voltage, the movable member 15 moves in the α direction little by little according to the number of pulses.

  Further, when the movable member 15 is moved in the β direction, the pulse voltage of the sawtooth waveform applied to the electromechanical transducer 11 may be reversed so as to make a rapid rise and a gentle fall.

  Since the linear actuator as described above has high accuracy and high responsiveness and is quiet in operation, it is suitable for mounting on a small imaging device such as a digital camera or a mobile phone. That is, the movable member 15 and the lens frame that holds the imaging lens can be integrally formed, and the imaging lens can be moved in the optical axis direction to perform a focusing operation or a zooming operation.

  Further, a lens device driving mechanism that uses such a linear actuator to drive a lens barrel that holds a zoom lens is disclosed in a patent publication (see, for example, Patent Document 1).

JP-A-8-21946

  The imaging lens is arranged at a predetermined position so as to focus on an imaging element such as a CCD or CMOS during photographing. At this time, if the lens barrel holding the image pickup lens protrudes from the main body of the image pickup apparatus toward the subject, it becomes an obstacle to carrying when not photographing. Therefore, a technique for storing the lens barrel in the main body of the image pickup apparatus at the time of non-photographing is conventionally well-known.

  When a unit having a lens barrel that holds such an imaging lens is referred to as a lens barrel, the lens barrel includes a fixed cylinder that is fixed and a movable cylinder that holds the lens and is movable in the optical axis direction. Then, during photographing, the movable cylinder is extended from the fixed cylinder to the subject side, and during non-photographing, so-called collapsing is performed in which the movable cylinder is housed in the fixed cylinder. In this case, when the imaging lens is a single focus lens, one movable cylinder is sufficient. However, when the imaging lens is a zoom lens, the movable cylinder is composed of a plurality of movable cylinders having different outer diameters.

  Patent Document 1 is an invention relating to a lens barrel that holds a zoom lens. At the time of photographing, three movable cylinders including the first lens barrel, the second lens barrel, and the third lens barrel are extended in three stages with respect to the fourth lens barrel that is a fixed cylinder. Such a linear actuator is used. At this time, the drive shaft of the linear actuator that drives the first lens barrel is disposed outside the outer peripheral surface of the first lens barrel and inside the second lens barrel, and the drive shaft that drives the second lens barrel is the second. The drive shaft for driving the third lens barrel is arranged outside the outer peripheral surface of the lens barrel and inside the fourth lens barrel outside the outer peripheral surface of the third lens barrel. Yes. For this reason, the second lens barrel is considerably thicker than the first lens barrel, the third lens barrel is considerably thicker than the second lens barrel, and the fourth lens barrel is considerably thicker than the third lens barrel. As a whole, the lens barrel has a large outer diameter.

  On the other hand, an imaging apparatus such as a digital camera is required to be downsized, and a lens barrel attached to the imaging apparatus is also required to be downsized. However, the lens barrel described in Patent Document 1 is not suitable for such a demand. It is.

  The present invention has been made in view of such a problem, and an object of the present invention is to propose a lens barrel that does not increase in outer diameter even when the movable cylinder is driven by a linear actuator.

  The above object is achieved by the invention described below.

1. A fixed cylinder that is fixed, and at least one movable cylinder that is movable in the optical axis direction. The movable cylinder is extended toward the subject side from the fixed cylinder during photographing, and the movable cylinder is the fixed cylinder when not photographing. In the lens barrel housed in
A drive shaft integrated with the electromechanical conversion element is frictionally engaged with the movable cylinder, and the movable cylinder is driven along the drive shaft by displacement of the drive shaft due to expansion and contraction of the electromechanical conversion element.
The lens barrel characterized in that the drive shaft is arranged on the inner side of the inner peripheral surface of the movable cylinder.

2. The movable cylinder is composed of a plurality of movable cylinders having different outer diameters, and is positioned on the subject side in order of decreasing outer diameter during shooting,
2. The lens barrel according to 1 above, wherein the plurality of drive shafts that respectively drive the plurality of movable cylinders are arranged on the inner side of the inner peripheral surface of the movable cylinder having the smallest outer diameter.

  3. 3. The lens barrel according to 1 or 2 above, wherein a guide shaft for guiding the movable cylinder is disposed on the inner side of the inner peripheral surface of the movable cylinder.

  4). The electromechanical conversion element or a holding member for holding the electromechanical conversion element is fixed to the fixed cylinder or the movable cylinder, and the drive shaft is fitted into a through hole provided in the fixed cylinder or the movable cylinder. The lens barrel according to any one of 1 to 3, wherein the lens barrel is characterized in that

  5. The lens barrel according to any one of 2 to 4, wherein the plurality of drive shafts are arranged close to each other.

  6). The lens barrel according to any one of 2 to 5, wherein the plurality of guide shafts are arranged close to each other.

  7. Any one of the plurality of movable cylinders holds a shutter, and the shutter is provided with a notch at a position facing the plurality of drive shafts. Lens barrel.

  According to the lens barrel of the present invention, there is an effect that the outer diameter is not increased even if the movable cylinder is driven by the linear actuator.

It is a front view of a linear actuator. It is a perspective view of a linear actuator. It is a figure explaining the principle of operation of a linear actuator. It is a disassembled perspective view of a lens barrel. It is sectional drawing when a lens-barrel is retracted. It is sectional drawing when a lens barrel is extended so that a zoom lens may be in the state of a wide angle end. It is sectional drawing when a lens barrel is extended so that a zoom lens may be in a telephoto end state. It is AA sectional drawing in FIG. It is BB sectional drawing in FIG. It is the perspective view which looked at the fixed cylinder from the subject side. It is the perspective view which looked at the 2nd movable cylinder from the photographic subject side. It is a perspective view of a fixed plate or the like.

  Embodiments relating to the lens barrel of the present invention will be described in detail with reference to the drawings.

  First, an outline of the lens barrel will be described with reference to FIGS. FIG. 4 is an exploded perspective view of the lens barrel. 5 is a sectional view when the lens barrel is retracted, FIG. 6 is a sectional view when the lens barrel is extended so that the zoom lens is in the wide-angle end state, and FIG. 7 is a state in which the zoom lens is at the telephoto end. 1 is a cross-sectional view when the lens barrel is drawn out so as to become, and each drawing is a cross-sectional view of the lens barrel cut horizontally. 8 is a cross-sectional view taken along line AA in FIG. 5, and FIG. 9 is a cross-sectional view taken along line BB in FIG.

  The imaging lens incorporated in the lens barrel is a zoom lens having a three-group configuration, and includes a first lens group L1, a second lens group L2, and a third lens group L3. Then, the first lens group L1, the second lens group L2, and the third lens group L3 move in the direction of the optical axis O while performing mutual zooming while changing the distance between the groups. The third lens unit L3 also moves in the direction of the optical axis O to perform focusing.

  This lens barrel has three cylindrical members having different inner and outer diameters, and the cylindrical member includes a first movable cylinder 21, a second movable cylinder 22, and a fixed cylinder 23 from the subject side. The outer diameter of the first movable cylinder 21 is smaller than the inner diameter of the second movable cylinder 22, and the outer diameter of the second movable cylinder 22 is smaller than the inner diameter of the fixed cylinder 23.

  A first lens frame 21 a that holds the first lens unit L <b> 1 is integrally formed inside the first movable cylinder 21. The first movable cylinder 21 is driven in the direction of the optical axis O by a linear actuator 30 fixed inside the second movable cylinder 22.

  Inside the second movable cylinder 22, a second lens frame 25 that holds the second lens unit L2 is disposed. The second lens frame 25 integrally holds a shutter 26 on the subject side. The second lens frame 25 is driven in the direction of the optical axis O by a linear actuator 40 fixed inside the second movable cylinder 22.

  The second movable cylinder 22 is driven in the direction of the optical axis O by a linear actuator 50 fixed inside the fixed cylinder 23.

  A fixed plate 27 is fixed integrally to the fixed cylinder 23 by a small screw 29 on the imaging surface side. A third lens frame 28 that holds the third lens unit L3 is disposed on the subject side of the fixed plate 27. The third lens frame 28 is moved in the direction of the optical axis O by a linear actuator 60 fixed to the fixed plate 27. Driven.

  Next, the operation of the lens barrel by these linear actuators 30 to 60 will be described with reference to FIGS. 10 is a perspective view of the fixed cylinder as seen from the subject side, FIG. 11 is a perspective view of the second movable cylinder as seen from the subject side, and FIG. 12 is a perspective view of the fixed plate and the like.

  First, assuming that the lens barrel is in the retracted state shown in FIG. 5 where imaging is not performed, the operation of drawing out from the retracted state to a state where imaging is possible will be described.

  The linear actuator 50 has the same configuration as the linear actuator 10 described above, and includes an electromechanical conversion element 51, a drive shaft 52, and a holding member 53.

  As shown in FIG. 10, the first holding portion 23a protrudes from the inner peripheral surface of the fixed cylinder 23 toward the center, and the arm portion 23b extends in a direction parallel to the optical axis O from the first holding portion 23a. A second holding portion 23c is provided at the tip of the portion 23b. The first holding portion 23a is provided with a through hole 23d. The electromechanical conversion element 51 of the linear actuator 50 is fitted into the through hole 23d, and the holding member 53 is fixed to the rear portion of the first holding portion 23a. The second holding portion 23c is also provided with a through hole 23e, and the drive shaft 52 is loosely fitted into the through hole 23e.

  On the other hand, as shown in FIGS. 9 and 11, the engaging portion 22a protrudes from the inner peripheral surface of the second movable cylinder 22 toward the center, and a V groove 22b is formed at the tip of the engaging portion 22a. The drive shaft 52 is engaged with the V groove 22b, and a U-shaped leaf spring 56 is mounted on the engagement portion 22a so as to hold the drive shaft 52. At this time, since a hole (not shown) provided in the leaf spring 56 is engaged with the protrusion 22c provided at the side end of the engaging portion 22a, the leaf spring 56 does not come off.

  The drive shaft 52 is disposed inside the inner peripheral surface of the first movable cylinder 21 as shown in FIG.

  Further, a guide shaft 57 is implanted in parallel with the optical axis O on the fixed plate 27 assembled integrally with the fixed cylinder 23, and the guide shaft 57 is arranged on the inner periphery of the second movable cylinder 22 as shown in FIG. It is fitted with a guide hole 23g provided in the guide portion 23f protruding from the surface toward the center.

  The guide shaft 57 is disposed on the inner side of the inner peripheral surface of the first movable cylinder 21.

  Thus, the drive shaft 52 is pressed against the V groove 22b by the leaf spring 56 with an appropriate pressure, and the drive shaft 52 and the V groove 22b are frictionally engaged. Therefore, by continuously applying a sawtooth waveform pulse voltage to the electromechanical transducer 51, the engaging portion 22a frictionally engaged with the drive shaft 52 is driven by the same principle as the linear actuator 10 described above. Then, the second movable cylinder 22 moves in the direction of the optical axis O along the drive shaft 52 and the guide shaft 57. Then, the second movable cylinder 22 is extended from the state of FIG. 5 to the state of FIG. Note that the linear actuator 50 is not shown in FIGS.

  After the second movable cylinder 22 moves in this way, the first movable cylinder 21, the second lens frame 25, and the third lens frame 28 also move. These movements will be described.

  The first movable cylinder 21, the second lens frame 25 and the third lens frame 28 are driven by linear actuators 40, 30 and 60. The linear actuators 40, 30, and 60 have the same configuration as the linear actuator 10 described above, and include electromechanical conversion elements 41, 31, 61, drive shafts 42, 32, 62, and holding members 43, 33, 63, respectively.

  As shown in FIG. 11, the first holding portion 22d protrudes from the inner peripheral surface of the second movable cylinder 22 toward the center, and the arm portion 22e extends from the first holding portion 22d in a direction parallel to the optical axis. A second holding portion 22f is provided at the tip of the arm portion 22e. The first holding portion 22d is provided with a through hole 22g, and the electromechanical conversion element 41 of the linear actuator 40 is fitted into the through hole 22g, and the holding member 43 is fixed to the rear portion of the first holding portion 22d. The second holding portion 22f is also provided with a through hole 22h, and the drive shaft 42 is loosely fitted into the through hole 23h. The first holding portion 22d is provided with a through hole 22i. The electromechanical transducer 31 of the linear actuator 30 is fitted into the through hole 22i, and the holding member 33 is fixed to the rear portion of the first holding portion 22d. The second holding portion 22f is also provided with a through hole 22j, and the drive shaft 32 is loosely fitted into the through hole 22j.

  Further, as shown in FIG. 8, an engaging portion 25a protrudes from the outer peripheral surface of the second lens frame 25, and a V groove 25b is formed at the tip of the engaging portion 25a. The drive shaft 42 of the linear actuator 40 is engaged with the V groove 25b, and a U-shaped leaf spring 46 is attached to the engagement portion 25a so as to hold the drive shaft 42. At this time, since a hole (not shown) provided in the leaf spring 46 is engaged with the protrusion 25c provided at the side end of the engaging portion 25a, the leaf spring 46 does not come off.

  The drive shaft 42 is disposed on the inner side of the inner peripheral surface of the first movable cylinder 21 as shown in FIG.

  Further, a guide shaft 47 is implanted in the second movable cylinder 22 in parallel with the optical axis O, and the guide shaft 47 is fitted into a notch 25d provided in the second lens frame 25 as shown in FIG.

  The guide shaft 47 is disposed on the inner side of the inner peripheral surface of the first movable cylinder 21.

  Thus, the drive shaft 42 is pressed against the V groove 25b by the leaf spring 46 with an appropriate pressure, and the drive shaft 42 and the V groove 25b are frictionally engaged. Therefore, by continuously applying a sawtooth waveform pulse voltage to the electromechanical transducer 41, the engaging portion 25a frictionally engaged with the drive shaft 42 is driven by the same principle as the linear actuator 10 described above. Then, the second lens frame 25 moves in the optical axis direction along the drive shaft 42 and the guide shaft 47. Then, the second lens frame 25, the shutter 26, and the second lens group L2 are extended from the state of FIG. 5 to the state of FIG.

  The drive shaft 42 is disposed on the inner side of the inner peripheral surface of the first movable cylinder 21 as shown in FIG.

  Next, as shown in FIG. 9, the engaging portion 21b protrudes from the inner peripheral surface of the first movable cylinder 21 toward the center, and a V-groove 21c is formed at the tip of the engaging portion 21b. The drive shaft 32 of the linear actuator 30 is engaged with the V groove 21c, and a U-shaped leaf spring 36 is mounted on the engagement portion 21b so as to hold the drive shaft 32. At this time, since a hole (not shown) provided in the leaf spring 36 is engaged with the protrusion 21d provided on the side end of the engaging portion 21b, the leaf spring 36 does not come off.

  Further, a guide shaft 37 is implanted in the second movable cylinder 22 in parallel with the optical axis O, and the guide shaft 37 has a guide portion 21e protruding toward the center from the first movable cylinder 21 as shown in FIG. It is fitted with the provided guide hole 21f.

  The guide shaft 37 is disposed on the inner side of the inner peripheral surface of the first movable cylinder 21.

  Thus, the drive shaft 32 is pressed against the V groove 21c by the leaf spring 36 with an appropriate pressure, and the drive shaft 32 and the V groove 21c are frictionally engaged. Accordingly, by continuously applying a sawtooth waveform pulse voltage to the electromechanical transducer 51, the engagement portion 21b frictionally engaged with the drive shaft 32 is driven by the same principle as the linear actuator 10 described above. Then, the first movable cylinder 21 moves in the optical axis direction along the drive shaft 32 and the guide shaft 37. Then, the first movable cylinder 21 and the first lens unit L1 are extended from the state of FIG. 5 to the state of FIG. Note that the linear actuator 30 is not shown in FIGS.

  Further, as shown in FIGS. 4 to 7 and 12, the holding member 63 of the linear actuator 60 is fixed to the rear portion of the fixed plate 27, and the drive shaft 62 protrudes toward the subject side. The fixing plate 27 is provided with a holding portion 27a, and the tip of the drive shaft 62 is loosely fitted in a hole 27b provided in the holding portion 27a.

  9 and 12, an engaging portion 28a protrudes from the outer peripheral surface of the third lens frame 28, and a V groove 28b is formed at the tip of the engaging portion 28a. The drive shaft 62 is engaged with the V groove 28b, and a U-shaped leaf spring 66 is attached to the engagement portion 28a so as to hold the drive shaft 62. At this time, since a hole (not shown) provided in the leaf spring 66 is engaged with the protrusion 28c provided at the side end of the engaging portion 28a, the leaf spring 66 does not come off.

  The drive shaft 62 is disposed inside the inner peripheral surface of the first movable cylinder 21 as shown in FIG.

  Further, a guide shaft 67 is implanted in the fixed plate 27 in parallel with the optical axis O, and the guide shaft 67 is fitted with a notch 28e provided in a guide portion 28d protruding from the outer peripheral surface of the third lens frame 28. is doing.

  The guide shaft 67 is disposed on the inner side of the inner peripheral surface of the first movable cylinder 21.

  Thus, the drive shaft 62 is pressed against the V groove 28b by the leaf spring 66 with an appropriate pressure, and the drive shaft 62 and the V groove 28b are frictionally engaged. Therefore, by continuously applying a sawtooth waveform pulse voltage to the electromechanical transducer 61, the engaging portion 28a frictionally engaged with the drive shaft 62 is driven by the same principle as the linear actuator 10 described above. The third lens frame 28L3 moves along the drive shaft 62 and the guide shaft 67 in the optical axis direction. Then, the third lens frame 28 and the third lens unit L3 are extended from the state of FIG. 5 to the state of FIG.

  Here, it is desirable to arrange the drive shafts 52, 42, and 32 as close as possible for efficient use of the internal space, and the same applies to the guide shafts 57, 47, and 37.

  In addition, the shutter 26 is provided with a notch 26a at a position facing the drive shafts 52, 42, and 32 that are arranged close to each other, so that the drive shafts 52, 42, and 32 can pass therethrough.

  As described above, the second lens frame 25, the shutter 26, and the second lens group L2 move in the direction of the optical axis O by the operation of the linear actuator 40, and the first movable cylinder 21 and the first lens group by the operation of the linear actuator 30. L1 moves in the direction of the optical axis O, and the third lens frame 28 and the third lens unit L3 move in the direction of the optical axis O by the operation of the linear actuator 60. Accordingly, the first lens group L1, the second lens group L2, and the third lens group L3 are extended to predetermined positions as shown in FIG. 6 and set to the wide-angle end state.

  In order to change from the wide-angle end state to the telephoto state, the first lens unit L1, the second lens unit L2, and the third lens unit L3 are mutually operated by operating the linear actuators 40, 30, and 60 in the same manner as described above. It moves to a predetermined position on the optical axis while changing the inter-group distance, and is set to a desired focal length state. Eventually, the telephoto end state shown in FIG. 7 is obtained.

  In this way, when zooming is performed and a desired focal length is set, and then imaging is performed, focusing is performed based on distance information from a camera (not shown). The focusing is performed by operating the linear actuator 60 and moving only the third lens unit L3 in the direction of the optical axis O.

  After imaging, the first movable cylinder 21, the second lens frame 25, the second movable cylinder 22 and the like are retracted into the fixed cylinder 23 by operating the linear actuators 40, 30, 60 in the reverse direction. The retracted state shown in FIG.

  It is necessary to detect that a member driven by each linear actuator has moved to a predetermined position, and a position sensor for this purpose is required. Although not shown in each drawing, as this position sensor, for example, an MR sensor comprising a magnetoresistive effect element (MR element) can be used. Further, a Hall element or a photo sensor may be used.

  As described above, each drive shaft of the linear actuator incorporated in the lens barrel is disposed on the inner side of the inner peripheral surface of the first movable cylinder 21 that is the movable cylinder having the narrowest outer diameter. It can suppress that the whole outer diameter becomes thick with a drive shaft.

  Each guide shaft is also preferably disposed on the inner side of the inner peripheral surface of the first movable cylinder 21 which is the movable cylinder having the smallest outer diameter. However, for example, a long groove parallel to the optical axis O is formed on the inner peripheral surface of the fixed cylinder, a long protrusion is formed on the outer peripheral surface of the second movable cylinder 22 in parallel with the optical axis O, and the convex portion is formed in the long groove. The second movable cylinder 22 does not rotate and the guide shaft 57 becomes unnecessary. Therefore, each guide shaft is not necessarily an essential component for the present invention.

  The above lens barrel has two movable cylinders, but there may be one movable cylinder or three or more movable cylinders.

  Each movable cylinder described above holds a lens group, but may be a single lens.

  Further, the imaging lens incorporated in the lens barrel may not be a zoom lens but may be a single focus lens.

  In addition, a part of each movable cylinder may hold a shutter, a filter, or the like instead of a lens group or a single lens. In some cases, it is provided only for extending the feeding length and holds nothing. Also good.

  The linear actuators 30 to 60 may not have the holding portions 33 to 63, and the electromechanical conversion elements 31 to 61 may be directly fixed to a predetermined member.

  Moreover, in the above each figure, the flexible printed circuit board electrically connected with the electromechanical conversion elements 31-61 is abbreviate | omitted.

10, 30, 40, 50, 60 Linear actuator 11, 31, 41, 51, 61 Electromechanical transducer 12, 32, 42, 52, 62 Drive shaft 13, 33, 43, 53, 63 Holding member 16a, 21c, 22b, 25b, 28b V-groove 17, 36, 46, 56, 66 Leaf spring 21 First movable cylinder 21a First lens frame 22 Second movable cylinder 23 Fixed cylinder 25 Second lens frame 26 Shutter 27 Fixed plate 28 Third mirror Frame 37, 47, 57, 67 Guide shaft L1 First lens group L2 Second lens group L3 Third lens group O Optical axis

Claims (7)

A fixed cylinder that is fixed, and at least one movable cylinder that is movable in the optical axis direction. The movable cylinder is extended toward the subject side from the fixed cylinder during photographing, and the movable cylinder is the fixed cylinder when not photographing. In the lens barrel housed in
A drive shaft integrated with the electromechanical conversion element is frictionally engaged with the movable cylinder, and the movable cylinder is driven along the drive shaft by displacement of the drive shaft due to expansion and contraction of the electromechanical conversion element.
The lens barrel characterized in that the drive shaft is arranged on the inner side of the inner peripheral surface of the movable cylinder. The movable cylinder is composed of a plurality of movable cylinders having different outer diameters, and is positioned on the subject side in order of decreasing outer diameter during shooting,
2. The lens barrel according to claim 1, wherein the plurality of drive shafts that respectively drive the plurality of movable cylinders are disposed on the inner side of the inner peripheral surface of the movable cylinder having the smallest outer diameter.   3. The lens barrel according to claim 1, wherein a guide shaft that guides the movable cylinder is disposed on an inner side of an inner peripheral surface of the movable cylinder. 4.   The electromechanical conversion element or a holding member for holding the electromechanical conversion element is fixed to the fixed cylinder or the movable cylinder, and the drive shaft is fitted into a through hole provided in the fixed cylinder or the movable cylinder. The lens barrel according to any one of claims 1 to 3, wherein:   The lens barrel according to claim 2, wherein the plurality of drive shafts are arranged close to each other.   The lens barrel according to claim 2, wherein the plurality of guide shafts are arranged close to each other.   Any one of the plurality of movable cylinders holds a shutter, and the shutter is provided with a notch at a position facing the plurality of drive shafts. The lens barrel described.

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