JP4891699B2 - Lens barrel - Google Patents

Description

  The present invention relates to a lens barrel that moves a lens in the optical axis direction, and more particularly to a lens barrel that relatively moves a plurality of lens barrels holding lenses in the optical axis direction.

  As shown in FIG. 11, a conventional lens barrel is fixed to a base 1 and has a fixed cylinder 2 having a cam groove on its inner peripheral surface. A rotary cylinder 3 having a cam groove on the inner peripheral surface and a first lens cylinder (straight-advance cylinder) 4 and a first lens cylinder 4 which are arranged inside the rotary cylinder 3 and move relatively in the optical axis direction L by a cam action; A guide cylinder (key cylinder) 6 that restricts the two-lens cylinder 5, the first lens cylinder 4 and the second lens cylinder 5 to be non-rotatable and guides only in the optical axis direction L, a drive mechanism for driving the rotating cylinder 3, and the like are provided. By rotating the rotary cylinder 3, the first lens cylinder 4 and the second lens cylinder 5 are moved relative to each other in the optical axis direction L to perform zooming. It is known that a part of a lens tube overlaps in the optical axis direction L. That (for example, Patent Document 1, Patent Document 2, Patent Document 3).

However, in this lens barrel, in order to overlap the first lens cylinder 4 and the second lens cylinder 5 in the optical axis direction L, the lens barrel is long in the optical axis direction L with respect to the wall surface of the first lens cylinder 4. A cutout portion 4a is provided, and the arm portion 5a holding the follower pin of the second lens cylinder 5 enters the cutout portion 4a.
Accordingly, when the mechanical strength of the first lens cylinder 4 located on the outside is reduced and the lens barrel receives an impact due to dropping or the like, the follower pin of the first lens cylinder 4 is dropped from the cam groove of the rotating cylinder, and the first There is a possibility that the lens cylinder 4 is depressed inside the rotary cylinder 3.
Further, the light that has entered from the lens of the first lens tube 4 may leak into the inside through the notch 4a and cause ghost, flare and the like.
Further, the length of the notch 4a provided in the first lens cylinder 4 is limited, and it has been difficult to reduce the length by retracting the entire length when retracted.

JP 2003-57705 A JP 2001-215387 A JP 2004-252365 A

  The present invention has been made in view of the above-mentioned problems of the prior art, and its object is to reduce the overall length in the optical axis direction, reduce the thickness, reduce the size in the radial direction, and the like. An object of the present invention is to provide a lens barrel that can secure the mechanical strength of the lens barrel, prevent light leakage, ghost, flare, and the like, and can be thinned particularly when retracted.

The lens barrel of the present invention has a cam barrel having a plurality of cam grooves that exert cam action in the optical axis direction by rotation on the inner peripheral surface, and is arranged in the optical axis direction inside the cam barrel and engages with the cam groove. A lens barrel comprising at least two lens frames each having a follower pin to be arranged, and a guide tube having a guide groove disposed between the cam tube and the lens frame and guiding the lens frame in the optical axis direction, The at least two lens frames include a first lens frame and a second lens frame arranged in order from the front in the optical axis direction. The first lens frame includes a first holding unit that holds the lens, and a first holding unit. A first cylindrical portion formed around and a first follower pin provided outside the first cylindrical portion, the second lens frame includes a second holding portion that holds the lens, and a second holding portion The first len while extending in the radial direction Includes a bent portion in the optical axis direction rear is formed by bending from the radially inner side of the first cylindrical portion so as to go around the outside of the frame, a second follower pin which is provided in the bent portion, the bent portion is at least In the retracted state, the first cylindrical portion is formed so as to overlap in the optical axis direction.
According to this configuration, at least two lens frames (the first lens frame and the second lens frame) have their follower pins engaged with the cam grooves of the cam cylinder through the guide grooves of the guide cylinder. When the cam cylinder rotates, the two lens frames move relatively in the optical axis direction in a state where the rotation around the optical axis is restricted by the guide cylinder.
In particular, the first lens frame includes a first holding part, a first cylindrical part, and a first follower pin, and is disposed on the object side, and the second lens frame includes a second holding part, a bent part, and a second The follower pin is included and is arranged behind the first lens frame. When the first lens frame and the second lens frame are in the retracted state, the bent portion of the second lens frame is in relation to the first cylindrical portion of the first lens frame. Thus, in the rear of the optical axis direction, it goes from the inner side to the outer side in the radial direction and overlaps (overlaps) in the optical axis direction.
Therefore, since it is not necessary to provide the conventional notch in the first lens frame (the first cylindrical portion) , the first lens frame machine can be achieved while reducing the thickness and size of the lens barrel when retracted. It is possible to increase the mechanical strength, to prevent the follower pin from falling off the cam groove, and to prevent light leakage, ghost, flare and the like that occur through the notch.

In the above configuration, the bent portion of the second lens frame is formed so as to overlap the first cylindrical portion of the first lens frame in the optical axis direction in a predetermined region in the moving range from the wide-angle end to the telephoto end. Can be adopted.
According to this configuration, the second lens frame (bent portion thereof ) overlaps the first lens frame (first cylindrical portion thereof ) in the optical axis direction even in a predetermined region of the moving range from the wide-angle end to the telephoto end (overshoot). As described above, the mechanical strength of the first lens frame can be increased, the follower pin can be prevented from falling off the cam groove, and light leakage caused through the notch can be prevented. It is possible to prevent phenomena such as ghost and flare, and to increase the relative movement amount of the lenses held in the two lens frames, and to expand the range of specifications set as a zoom lens. Can do.

In the above configuration, the bent portion is formed so as to extend radially outward from the second holding portion, and to extend forward from the arm portion in the optical axis direction, and is slidably fitted into the guide groove. It is possible to employ a configuration in which a second follower pin is provided so as to protrude radially outward, including a sliding portion to be joined.
According to this configuration, in the second lens frame, the bent portion is accommodated in the guide groove of the guide cylinder and the rotation around the optical axis is restricted, and the second follower pin provided on the outer side of the bent section is the guide cylinder. Since it is engaged with the cam groove of the cam cylinder located on the outside, it is not necessary to provide a dedicated space as a space for arranging the bent part, and the structure is simplified and the diameter is reduced, and the thickness is reduced when retracted. Can be achieved.

The said structure WHEREIN: The structure by which the bending part is formed in the thickness accommodated in the guide groove of a guide cylinder is employable.
According to this configuration, the first lens frame has the first cylindrical portion disposed inside the guide tube (for example, held so as to slide on the inner peripheral surface), and the first follower pin of the guide tube. The second lens frame is engaged with the cam groove of the cam cylinder located on the outside through the guide groove from the inside, and the bent portion extending from the second holding portion is accommodated in the guide groove of the guide cylinder so as to be around the optical axis. The second follower pin provided outside the bent portion is engaged with the cam groove of the cam cylinder located outside the guide cylinder.
Therefore, it is not necessary to provide a dedicated space as a space for arranging the bent portion, and it is possible to achieve a reduction in thickness when retracted while achieving a simplified structure and a reduced diameter.

In the above configuration, the cam cylinder includes a first inner peripheral surface having a predetermined inner diameter, a second inner peripheral surface having an inner diameter larger than the first inner peripheral surface, and a first cam groove for engaging the first follower pin. And a second cam groove that engages the second follower pin, the first cam groove is formed on the first inner peripheral surface and the second inner peripheral surface, and the second cam groove is formed on the second inner peripheral surface. The bent portion can be configured to protrude radially outward from the guide groove of the guide tube.
According to this configuration, the cam cylinder has the two-step inner peripheral surfaces (the first inner peripheral surface having a small diameter and the second inner peripheral surface having a large diameter) having different inner diameters, and thus the first lens frame and the second lens frame are arranged. It can be surely assembled, and without increasing the thickness of the guide tube, the thickness of the bent portion can be increased to further increase the mechanical strength and fitting accuracy.

  According to the lens barrel having the above configuration, the mechanical strength of the lens barrel can be ensured while achieving a reduction in the overall length in the optical axis direction, a reduction in thickness and a reduction in size in the radial direction, and light leakage. Alternatively, it is possible to obtain a lens barrel that can prevent phenomena such as ghost and flare.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, exemplary embodiments of the invention will be described with reference to the accompanying drawings.
1 to 4 show an embodiment of a lens driving device incorporating a lens barrel according to the present invention, FIG. 1 is an exploded perspective view of the device, and FIG. 2 is a second view included in the lens barrel. FIG. 3 and FIG. 4 are cross-sectional views of the apparatus.

  As shown in FIGS. 1 to 4, this apparatus includes a glass filter 11, a base 10 having a substantially rectangular outline to which a CCD 12 or the like as an imaging device is attached, a fixed cylinder 20 fixed to the base 10, a fixed cylinder 20 is a cam cylinder 30 that is supported so as to be rotatable and rectilinearly movable inside 20, and a first lens frame 40 and a second lens frame 50 that are supported so as to be movable in the optical axis direction L inside the cam cylinder 30, and a first lens frame. 40 and the second lens frame 50 are driven to drive the guide tube 60 that guides in the optical axis direction, the third lens frame 70 supported movably in the optical axis direction L with respect to the base 10, and the cam tube 30. And a drive mechanism (not shown) for driving the third lens frame 70.

  As shown in FIGS. 1, 3, and 4, the fixed cylinder 20 is formed in a cylindrical shape with a resin material so as to have an axis in the optical axis direction L, and is fixed to the base 10. Three cam grooves 21 (partially omitted in the figure) are formed on the inner peripheral surface 20a of the fixed cylinder 20 to effect cam action on three follower pins 31 described later.

As shown in FIGS. 1, 3, and 4, the cam cylinder 30 is formed in a cylindrical shape from a resin material, and is arranged coaxially in a nested manner inside the fixed cylinder 20. On the outer peripheral surface 30a of the cam barrel 30, there are formed three follower pins 31 arranged at equal intervals (approximately every 120 degrees) in the circumferential direction, an arc-shaped rack portion 32 to which a rotational driving force is transmitted from the outside, and the like. .
As shown in FIGS. 3 and 4, the cam barrel 30 has three cam grooves 33 that have a cam action on the first lens frame 40 in the optical axis direction L, and a second lens in the optical axis direction L, as shown in FIGS. Three cam grooves 34 that exert a cam action on the frame 50, and an annular groove 35 that receives an engagement piece 63 of a guide cylinder 60 described later in the front region in the optical axis direction L are formed.

As shown in FIGS. 3 and 4, the cam groove 33 has a substantially V-shaped cross section so as to receive (engage) a first follower pin 43 described later. That is, the cam groove 33 exerts a cam action via the first follower pin 43 to move the first lens frame 40 in the optical axis direction L.
As shown in FIGS. 3 and 4, the cam groove 34 has a substantially V-shaped cross section so as to receive (engage) a second follower pin 53 described later. That is, the cam groove 34 exerts a cam action via the second follower pin 53 to move the second lens frame 50 in the optical axis direction L.

As shown in FIGS. 1, 3, and 4, the first lens frame 40 is formed in a substantially cylindrical shape with a resin material so as to surround the first holding portion 41 and the first holding portion 41 that hold the lens G <b> 1. A first cylindrical portion 42 formed around the first cylindrical portion 42, and three first follower pins 43 provided so as to protrude outward in the radial direction outside the first cylindrical portion 42. The three first follower pins 43 are arranged at regular intervals (every 120 degrees) in the circumferential direction, and are formed in a substantially conical shape so as to be slidably engaged with the cam grooves 33, respectively.
The first lens frame 40 moves forward and backward in the optical axis direction L when the cam cylinder 30 rotates and the cam groove 33 exerts a cam action on the first follower pin 43.

As shown in FIGS. 1 to 4, the second lens frame 50 is formed in a substantially cylindrical shape by a resin material, and extends in the radial direction from the second holding part 51 that holds the lens G <b> 2 and the second holding part 51 ( And a bent portion 52 formed by bending so as to wrap around from the inside to the outside of the first tubular portion 42, and three provided so as to protrude radially outward with respect to the bent portion 52 A second follower pin 53 is provided. The three second follower pins 53 are arranged at regular intervals (every 120 degrees) in the circumferential direction, and are formed in a substantially conical shape so as to be slidably engaged with the cam grooves 34, respectively.
The second lens frame 50 moves forward and backward in the optical axis direction L when the cam cylinder 30 rotates and the cam groove 34 exerts a cam action on the second follower pin 53.

Here, as shown in FIG. 1 to FIG. 4, the bent portion 52 is formed by bending in an approximately L shape, and extends from the second holding portion 51 in the radially outward direction, an arm portion 52 a and an arm portion 52 a. And a sliding portion 52b that bends approximately 90 degrees forward and is slidably fitted in a guide groove 62 of a guide cylinder 60 described later. As shown in FIGS. 3 and 4, the sliding portion 52 b is formed to have a thickness substantially the same as the thickness of the guide tube 60 (the depth of the guide groove 62).
As a result, the second lens frame 50 is configured such that the bent portion 52 is accommodated in a guide groove 62 of the guide tube 60 described later and rotation around the optical axis L is restricted, and the second lens frame 50 is provided outside the bent portion 52. The follower pin 53 is engaged with the cam groove 34 of the cam cylinder 30 located outside the guide cylinder 60. Therefore, it is not necessary to provide a dedicated space as a space for arranging the bent portion 52, and it is possible to achieve a reduction in thickness when retracted while achieving a simplified structure and a reduced diameter.

That is, as shown in FIG. 3, in the retracted state, the second lens frame 50 has the bent portion 52 that goes around from the inside to the outside of the first cylindrical portion 42 of the first lens frame 40 and overlaps in the optical axis direction L. It is like that.
Therefore, the first cylindrical portion 42 of the first lens frame 40 does not need to be provided with a cutout portion for preventing interference with the portion that holds the second follower pin 53. The mechanical strength can be increased while achieving a reduction in thickness and size, and the first follower pin 43 can be prevented from falling off the cam groove 33 due to an impact or the like. Further, since the conventional notch is not provided, it is possible to prevent light leakage, ghost, flare, and the like that occur through the gap between the first cylindrical portions 42.

As shown in FIGS. 1, 3, and 4, the guide tube 60 is disposed between the first lens frame 40 and the second lens frame 50 and the cam tube 30, and the first lens frame 40 and the second lens. The frame 50 is guided to reciprocate in the optical axis direction L while restricting rotation around the optical axis L.
That is, the guide tube 60 receives the first follower pin 43 of the first lens frame 40 and guides it in the optical axis direction L, and receives the second follower pin 53 of the second lens frame 50 and receives the first follower pin 43 in the optical axis direction L. The three guide grooves 62 for guiding the three cylinders, the three engaging pieces 63 engaged with the annular groove 35 formed in the inner peripheral surface 30b of the cam cylinder 30, and the optical axis L And a projection 64 and the like that are movably engaged with each other.
Here, the guide groove 61 and the guide groove 62 are arranged at equal intervals in the circumferential direction (at an angle of 120 degrees), and are slit-shaped (long holes) that are notched and extend in the optical axis direction L. The groove shape is defined in cooperation with the inner peripheral surface 30 b of the cam cylinder 30.

The guide cylinder 60 is engaged with the inner peripheral surface 30b of the cam cylinder 30, and the engagement piece 63 is engaged with the annular groove 35 so that the guide cylinder 60 does not move relatively in the optical axis direction L. Further, the projection 64 is hooked on the fixed cylinder 20 so that the guide cylinder 60 does not rotate (the cam cylinder 30 rotates relative to the guide cylinder 60).
Therefore, when the cam cylinder 30 rotates, the guide groove 61 of the guide cylinder 60 guides the first follower pin 43, which is cammed by the cam groove 33, so as to be able to reciprocate only in the optical axis direction L. The guide groove 62 guides the second follower pin 53, which is cammed by the cam groove 34, so as to freely reciprocate only in the optical axis direction L.

  As shown in FIGS. 1, 3, and 4, the third lens frame 70 holds the lens G3 and moves forward and backward in the optical axis direction L by a drive mechanism (not shown) to perform a focusing operation. It has become.

As shown in FIG. 1, the drive mechanism 80 includes a DC motor 81 fixed to the base 10, a gear train (not shown) that meshes with the rack portion 32 of the cam cylinder 30, and the like. Is transmitted to the cam cylinder 30.
That is, when the DC motor 81 rotates in one direction, the cam cylinder 30 rotates in one direction relative to the fixed cylinder 20 via the gear train, and passes through the wide-angle end position from the retracted position shown in FIG. When the first lens frame 40 and the second lens frame 50 move forward in the optical axis direction L and move to the telephoto end position as shown in FIG. 4, while the DC motor 81 rotates in the opposite direction, the gear train is changed. After the cam cylinder 30 rotates in the opposite direction relative to the fixed cylinder 20, the first lens frame 40 and the second lens frame 50 move rearward in the optical axis direction L and pass through the wide-angle end position. As shown in FIG. 3, it moves to the retracted position.

Next, a general operation when the lens driving device including the lens barrel described above is mounted on a digital camera will be described. First, at the time of non-shooting, the first lens frame 40, the second lens frame 50, and the As shown in FIG. 3, the three-lens frame 70 is in a retracted position that is retracted rearward in the optical axis direction L.
In this retracted state, the second lens frame 50 is in the optical axis direction L with the first lens frame 40 such that the bent portion 52 goes around the first cylindrical portion 42 of the first lens frame 40 from the inside to the outside. It is in an overlapping state.
Accordingly, it is possible to achieve a reduction in thickness and size in the optical axis direction L when retracted.

When the cam cylinder 30 is rotated from the retracted position by the drive mechanism 80, the follower pin 31 is guided and moved by the cam groove 21, and the cam cylinder 30 is advanced forward in the optical axis direction L. Further, the rotation of the cam cylinder 30 causes the first follower pin 43 to be cammed by the cam groove 33 while being guided only by the guide groove 61 in the optical axis direction L, and the second follower pin 53 is guided by the guide groove 62 in the optical axis direction. The first lens frame 40 and the second lens frame 50 are moved in the optical axis direction L while being restricted in rotation under the cam action of the cam groove 34 while being guided only by L, and reach the telephoto end position shown in FIG. It reaches. On the other hand, the third lens frame 70 is moved to a focus position corresponding to the positions of the first lens frame 40 and the second lens frame 50 by another driving mechanism.
On the other hand, when the driving mechanism 80 exerts a driving force in the opposite direction, the first lens frame 40 and the second lens frame 50 follow the reverse path and return to the retracted position shown in FIG. Return to the retracted position shown in FIG.

  During this series of operations, the first lens frame 40 and the second lens frame 50 are firmly formed without being provided with a cutout portion or the like even when subjected to an impact or the like from the outside. The two follower pins 53 move smoothly along the cam grooves 33, 34 without being disengaged from the cam grooves 33, 34, and a smooth zooming operation is obtained, thereby ensuring functional reliability.

  5 to 10 show another embodiment of a lens barrel according to the present invention. FIG. 5 is an exploded perspective view of a lens driving device provided with the lens barrel. FIG. FIG. 7 is a sectional view of the apparatus showing the state where the lens barrel is in the wide-angle end position, and FIG. 8 is a sectional view of the apparatus showing the state where the lens barrel is in the intermediate position. FIG. 9 is a sectional view of the apparatus showing a state in which the lens barrel is at the telephoto end position, and FIG. 10 is a partial development view showing a part of the inner peripheral surface of the cam cylinder. In this embodiment, the same components as those of the above-described embodiment are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIGS. 5 to 9, this apparatus includes a base 10, a fixed cylinder 20, a cam cylinder 30 ′ supported so as to be rotatable and rectilinear inside the fixed cylinder 20, and an optical axis direction inside the cam cylinder 30 ′. A guide that guides in the optical axis direction L while restricting the rotation of the first lens frame 40 ′ and the second lens frame 50 ′, and the first lens frame 40 ′ and the second lens frame 50 ′ supported movably by L. A drive mechanism 80 for driving the cylinder 60 and the cam cylinder 30 'is provided.

As shown in FIGS. 5 to 10, the cam cylinder 30 ′ is formed in a cylindrical shape from a resin material, and is arranged coaxially in a nested manner inside the fixed cylinder 20. Three follower pins 31, an arc-shaped rack portion 32, and the like are formed on the outer peripheral surface 30 a of the cam cylinder 30 ′.
As shown in FIGS. 5 to 10, the inner peripheral surface of the cam cylinder 30 has a first inner peripheral surface 60b ′ and a first inner peripheral surface 60b having a predetermined inner diameter with a boundary line BL (see FIG. 10) as a boundary. It is formed by a second inner peripheral surface 60b '' having an inner diameter larger than '.
The first inner peripheral surface 60b ′ and the second inner peripheral surface 60b ″ are formed with three first cam grooves 33 ′ that exert a cam action on the first lens frame 40 ′ in the optical axis direction L, and the second Three second cam grooves 34 ′ that have a cam action on the second lens frame 50 ′ in the optical axis direction L are formed on the inner peripheral surface 60 b ″. In the first inner peripheral surface 60b ', an annular groove 35 for receiving the engaging piece 63 of the guide tube 60 is formed in the front region in the optical axis direction L.

The first cam groove 33 ′ is formed in a substantially V-shaped cross section so as to receive (engage) the first follower pin 43 as shown in FIGS. 6 to 9, and exerts a cam action on the first follower pin 43. Thus, the first lens frame 40 ′ is moved in the optical axis direction L.
The second cam groove 34 ′ is formed in a substantially V-shaped cross section so as to receive (engage with) the second follower pin 53 as shown in FIGS. 6 to 9, and exerts a cam action on the second follower pin 53. Thus, the second lens frame 50 ′ is moved in the optical axis direction L.

As shown in FIGS. 5 to 9, the first lens frame 40 ′ is formed in a substantially cylindrical shape by a resin material, and is formed around the first holding portion 41 ′ and the first holding portion 41 ′. The first cylindrical portion 42, three first follower pins 43 provided so as to protrude radially outward on the outside of the first cylindrical portion 42, and slidably engaged with the first cam groove 33 ′, A driving mechanism 44 that drives the first holding portion 41 ′ in the optical axis direction L with respect to the first tubular portion 42 is provided.
The drive mechanism 44 includes a nut 44a fixed to the first holding portion 41 ′, a lead screw 44b screwed into the nut 44a and rotatably supported by the first cylindrical portion 42, and a gear that rotationally drives the lead screw 44b. 44c and a motor (not shown).
The first lens frame 40 ′ moves forward and backward in the optical axis direction L as the cam barrel 30 ′ rotates and the first cam groove 33 ′ exerts a cam action on the first follower pin 43. 1 holding | maintenance part 41 'moves relatively with respect to the 1st cylindrical part 42 with the drive mechanism 44. As shown in FIG.

As shown in FIGS. 5 to 9, the second lens frame 50 ′ is formed in a substantially cylindrical shape by a resin material, and extends in the radial direction from the second holding portion 51 that holds the lens G2, and from the second holding portion 51. (Extends) and is bent so as to be bent from the inside to the outside of the first cylindrical portion 42, and is provided so as to protrude radially outward with respect to the bent portion 52 '. Three second follower pins 53 that are slidably engaged with the second cam grooves 34 ′, a shutter mechanism 54, and the like are provided.
The second lens frame 50 ′ moves forward and backward in the optical axis direction L when the cam barrel 30 ′ rotates and the second cam groove 34 ′ exerts a cam action on the second follower pin 53. ing.

Here, as shown in FIGS. 6 to 9, the bent portion 52 ′ is formed by bending in an approximately L shape or U shape, and extends from the second holding portion 51 in the radially outward direction. ′, A sliding portion 52b ′ that bends approximately 90 degrees forward from the arm portion 52a ′.
The sliding portion 52b ′ has a side surface slidably fitted in the guide groove 62, protrudes radially outward from the guide groove 62, and an end surface thereof is a second inner peripheral surface 60b ′ of the cam cylinder 30 ′. 'Is slidably contacted.
The second follower pin 53 protruding from the end face of the sliding portion 52b ′ is slidably engaged with the second cam groove 34 ′ of the cam cylinder 30 ′.
That is, the bent portion 52 ′ is formed so as to protrude radially outward from the guide groove 62 of the guide tube 60, as shown in FIGS. 6 to 9. Accordingly, the second lens frame 50 ′ can further increase the mechanical strength and the fitting accuracy by increasing the thickness of the bent portion 52 ′ without increasing the thickness of the guide tube 30 ′.

Further, as shown in FIGS. 6, 8, and 9, the second lens frame 50 ′ is not only in the retracted position, but also in a predetermined region of the moving range from the wide angle end to the telephoto end, that is, in the intermediate position and the telephoto end position. The bent portion 52 ′ extends from the inside to the outside of the first cylindrical portion 42 of the first lens frame 40 ′ so as to overlap in the optical axis direction L.
Therefore, since it is not necessary to provide a notch in the first cylindrical portion 42 of the first lens frame 40 ', the mechanical strength of the lens barrel can be increased while reducing the thickness and size of the lens barrel when retracted. It is possible to prevent the first follower pin 43 from falling off the first cam groove 33 ′ due to impact or the like. Further, since the conventional notch is not provided, it is possible to prevent light leakage, ghost, flare, and the like that occur through the gap between the first cylindrical portions 42.
The first lens frame 40 'and the second lens frame 50' have two-step inner peripheral surfaces (small first inner peripheral surface 60b 'and large second inner peripheral surface 60b'') having different inner diameters. Since the first lens frame 40 'and the second lens frame 50' can be assembled without fail, the fitting accuracy can be improved.

Next, a general operation when the lens driving device including the lens barrel is mounted on a digital camera will be described. First, at the time of non-shooting, the first lens frame 40 ′ and the second lens frame 50 ′ are As shown in FIG. 6, the retracted position is retracted backward in the optical axis direction L.
In this retracted state, the second lens frame 50 ′ is light-transmitted with the first lens frame 40 ′ so that the bent portion 52 ′ wraps around the first cylindrical portion 42 of the first lens frame 40 ′ from the inside to the outside. It is in a state of overlapping in the axial direction L.
Accordingly, it is possible to achieve a reduction in thickness and size in the optical axis direction L when retracted.

  When the cam cylinder 30 ′ is rotated by the drive mechanism 80 from the retracted position, the follower pin 31 is guided and moved by the cam groove 21, and the cam cylinder 30 ′ is advanced toward the front in the optical axis direction L. Further, due to the rotation of the cam cylinder 30 ′, the first follower pin 43 receives the cam action by the first cam groove 33 ′ while being guided only in the optical axis direction L by the guide groove 61, and the second follower pin 53 is guided by the guide groove 62. Thus, the first lens frame 40 ′ and the second lens frame 50 ′ are restricted from rotating with respect to the cam barrel 30 ′ while receiving the cam action by the second cam groove 34 ′ while being guided only in the optical axis direction L. It moves forward and rearward in the optical axis direction L (positions indicated by W in the first cam groove 33 ′ and the second cam groove 34 ′ in FIG. 10) and reaches the wide-angle end position shown in FIG.

Subsequently, when the cam cylinder 30 ′ is rotated in the same direction by the drive mechanism 80, the rotation of the first lens frame 40 ′ and the second lens frame 50 ′ is restricted with respect to the cam cylinder 30 ′ and the optical axis direction It moves to the rear and front of L (the position indicated by M in the first cam groove 33 ′ and the second cam groove 34 ′ in FIG. 10), and reaches the intermediate position shown in FIG.
At this time, the bent portion 52 ′ of the second lens frame 50 ′ turns from the inside to the outside of the first cylindrical portion 42 of the first lens frame 40 ′ and overlaps the optical axis direction L by a predetermined amount. .

Further, when the cam cylinder 30 ′ is rotated in the same direction by the drive mechanism 80, the rotation of the first lens frame 40 ′ and the second lens frame 50 ′ is restricted with respect to the cam cylinder 30 ′ and the optical axis direction L 9 (positions indicated by T in the cam grooves 33 'and 34' in FIG. 10) move to the telephoto end position shown in FIG.
At this time, the bent portion 52 ′ of the second lens frame 50 ′ turns from the inside to the outside of the first cylindrical portion 42 of the first lens frame 40 ′ and overlaps.

On the other hand, when the driving mechanism 80 exerts a driving force in the opposite direction, the first lens frame 40 'and the second lens frame 50' follow the reverse path, and the retracted state shown in FIG. 6 from the telephoto end position shown in FIG. It comes to return to the position.
In the first lens frame 40 ′, in addition to the movement of the cam cylinder 30 ′ by the first cam groove 33 ′, the drive mechanism 44 drives the first holding part 41 ′ with respect to the first cylindrical part 42. Thus, the zooming operation and the focusing operation are performed by being relatively moved in the optical axis direction L.

During this series of operations, the first lens frame 40 ′ and the second lens frame 50 ′ are firmly formed without providing a cutout portion or the like even when receiving an impact or the like from the outside. The second follower pin 53 moves smoothly along the first cam groove 33 ′ and the second cam groove 34 ′ without detaching from the first cam groove 33 ′ and the second cam groove 34 ′, and smooth zooming operation And functional reliability is ensured.
Further, the second lens frame 50 ′ goes not only in the retracted state but also in a predetermined region in the moving range from the wide-angle end to the telephoto end, so that the second lens frame 50 ′ wraps around from the inside to the outside in the optical axis direction L. Since they overlap (overlapping), the relative movement amount of the lenses G1 and G2 can be increased, and the range of specifications set as a zoom lens can be expanded.

  In the above embodiment, the two lens frames 40, 50, (40 ′, 50 ′) are shown as the lens frames (lens group) that are moved in the optical axis direction L by the cam tubes 30, 30 ′. Three or more lens frames may be adopted as the lens frame driven by the above.

  As described above, the lens barrel of the present invention can achieve a reduction in thickness when retracted and can increase mechanical strength. The present invention can be applied to a silver salt film type camera as well as a camera, a digital video camera and the like.

It is a disassembled perspective view which shows one Embodiment of the lens drive device incorporating the lens-barrel concerning this invention. It is a perspective view which shows the 2nd lens frame contained in the lens barrel shown in FIG. It is sectional drawing which shows the state which the lens-barrel of the apparatus shown in FIG. 1 retracted. It is sectional drawing which shows the state which the lens-barrel of the apparatus shown in FIG. 1 pays out and exists in a telephoto end position. It is a disassembled perspective view which shows other embodiment of the lens drive device incorporating the lens-barrel concerning this invention. It is sectional drawing which shows the state which the lens-barrel of the apparatus shown in FIG. 5 retracted. It is sectional drawing which shows the state which has the lens-barrel of the apparatus shown in FIG. 5 in a wide-angle end position. It is sectional drawing which shows the state which the lens-barrel of the apparatus shown in FIG. 5 pays out and exists in an intermediate position. It is sectional drawing which shows the state which the lens-barrel of the apparatus shown in FIG. 5 pays out and exists in a telephoto end position. FIG. 6 is a development view showing a part of an inner peripheral surface of a cam cylinder included in the lens barrel shown in FIG. 5. It is sectional drawing which shows the conventional lens barrel.

Explanation of symbols

L Optical axis direction G1, G2, G3 Lens 10 Base 11 Glass filter 12 CCD
20 fixed cylinder 21 cam groove 30, 30 'cam cylinder 30b inner peripheral surface 30b' first inner peripheral surface 30b "second inner peripheral surface 31 follower pin 32 rack portion 33, 34 cam groove 33 'first cam groove 34' first 2 cam groove 35 annular groove 40, 40 'first lens frame (the other lens frame)
41, 41 '1st holding part 42 1st cylindrical part 43 1st follower pin 44 Drive mechanism 50, 50' 2nd lens frame (one lens frame)
51 Second holding portion 52, 52 'Bending portion 52a, 52a' Arm portion 52b, 52b 'Sliding portion 53 Second follower pin 54 Shutter mechanism 60 Guide cylinder 61, 62 Guide groove 63 Engagement piece 64 Projection 70 Third lens frame 80 Drive mechanism

Claims (5)

At least a cam cylinder having a plurality of cam grooves that cam in the optical axis direction by rotation on the inner peripheral surface, and a follower pin that is arranged in the optical axis direction inside the cam cylinder and engages with the cam groove. A lens barrel comprising two lens frames and a guide tube having a guide groove disposed between the cam tube and the lens frame and guiding the lens frame in the optical axis direction,
The at least two lens frames include a first lens frame and a second lens frame arranged in order from the front in the optical axis direction,
The first lens frame includes a first holding part for holding a lens, a first cylindrical part formed around the first holding part, and a first follower pin provided outside the first cylindrical part. Including
The second lens frame includes a second holding portion that holds a lens, and extends radially from the second holding portion and radially inward of the first cylindrical portion behind the first lens frame in the optical axis direction. A bent portion formed by bending so as to wrap around from the outside, and a second follower pin provided in the bent portion,
The bent portion is formed so as to overlap the first cylindrical portion in the optical axis direction at least in a retracted state.
A lens barrel characterized by that. The bent portion is formed so as to overlap the first tubular portion in the optical axis direction in a predetermined region of the moving range from the wide-angle end to the telephoto end.
The lens barrel according to claim 1. The bent portion is formed so as to extend radially outward from the second holding portion, and to extend forward from the arm portion in the optical axis direction, and is slidably fitted into the guide groove. Including sliding parts to be joined,
The sliding part is provided with the second follower pin so as to protrude outward in the radial direction.
The lens barrel according to claim 1 or 2, wherein The bent portion is formed to a thickness that fits in a guide groove of the guide cylinder.
The lens barrel according to claim 1, wherein the lens barrel is a lens barrel. The cam cylinder includes a first inner peripheral surface having a predetermined inner diameter, a second inner peripheral surface having an inner diameter larger than the first inner peripheral surface, and a first cam groove for engaging the first follower pin; Including a second cam groove for engaging the second follower pin;
The first cam groove is formed in the first inner peripheral surface and the second inner peripheral surface,
The second cam groove is formed on the second inner peripheral surface,
The bent portion is formed so as to protrude radially outward from the guide groove of the guide cylinder.
The lens barrel according to claim 1, wherein the lens barrel is a lens barrel.

Images