JP2012181461A - Lens barrel drive mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simple and small-sized lens barrel with large movement distance in an optical axis direction.SOLUTION: A lens barrel drive mechanism comprises: a first cam cylinder 4 that rotates and moves in an optical axis by receiving transmitted rotary drive; a first lens group frame 3 that holds a lens group on a subject side and moves in the optical direction in a manner engaging with an outer peripheral side of the first cam cylinder 4; a second cam cylinder 5 that rotates and moves in the optical axis direction in a manner engaging with an inner peripheral side of the first cam cylinder 4; and a second lens group frame 7 that holds a lens on an imaging element side and moves in the optical direction in a manner engaging with the inner peripheral side of the second cam cylinder 5. The first cam cylinder 4 and the second cam cylinder 5 differ in a rotation angle. Specifically, a circumferentially-parallel groove part 47L is provided perpendicularly to the optical axis at an end part on the imaging element side of a straight guide groove 47, which is provided at the first cam cylinder 4 and with which the second cam cylinder 5 engages, in a manner extending as long as an angle equivalent to a difference of the rotation angle between the first cam cylinder 4 and the second cam cylinder 5.

Description

  The present invention relates to a lens barrel driving mechanism of an imaging apparatus.

In recent years, further miniaturization of digital cameras has been demanded.
At the same time, there is also a demand for further performance improvements, so that the lens barrel does not increase the number of parts while reducing the overall configuration, while still ensuring the zoom lens driving distance and supporting high magnification. It is requested.
However, when the lens barrel is reduced, the cam groove formed in the cam cylinder is too steep, the cam grooves overlap each other, or the cam cylinder does not protrude from the cam cylinder.
Thus, for example, Patent Document 1 proposes a mechanism that secures the amount of movement of the lens group by causing a part of the cam groove to protrude from the cam cylinder.

JP 2007-139964 A

However, as in Patent Document 1, when a part of the cam groove is protruded from the cam cylinder, there is a disadvantage that the cam groove becomes complicated.
Therefore, there is a demand for a simple and small lens barrel that has a large amount of movement in the optical axis direction.

  An object of the present invention is to provide a simple and small lens barrel having a large amount of movement in the optical axis direction.

  In order to solve the above-described problems, the invention according to claim 1 is configured to hold a first cam cylinder that is rotated and moved in the direction of the rotation and the optical axis when rotational driving is transmitted, and a lens group on a subject side, and the first cam A first lens group frame that engages with the outer peripheral side of the cylinder and moves in the optical axis direction; a second cam cylinder that engages with the inner peripheral side of the first cam cylinder and rotates and moves in the optical axis direction; A lens barrel drive mechanism comprising: a second lens group frame that holds a lens on the imaging element side, engages with an inner peripheral side of the second cam cylinder, and moves in an optical axis direction, wherein the first cam The cylinder and the second cam cylinder have different rotation angles.

  A second aspect of the present invention is the lens barrel drive mechanism according to the first aspect, wherein the linear guide groove provided on the first cam cylinder and engaged with the second cam cylinder is on the image sensor side end. A groove portion that is orthogonal to the optical axis and parallel to the circumferential direction is extended in the portion by an angle corresponding to a difference in rotation angle between the first cam cylinder and the second cam cylinder.

  A third aspect of the present invention is the lens barrel drive mechanism according to the first or second aspect, wherein the first cam cylinder is engaged with the inner periphery of the first cam cylinder and the second cam cylinder, respectively. And a female helicoid that is provided on the key cylinder and engages with the second cam cylinder, between the retracted state of the lens barrel and the shootable state, The second cam cylinder is formed as a groove portion orthogonal to the optical axis and parallel to the circumferential direction so as not to move in the optical axis direction.

  According to the present invention, it is possible to provide a simple and small lens barrel that has a large amount of movement in the optical axis direction.

FIG. 1 is a perspective view illustrating an arrangement of an embodiment to which the present invention is applied, and is an exploded perspective view of parts constituting a lens barrel. It is the figure seen from the direction opposite to FIG. It is sectional drawing which shows the schematic structure in the PARK state of a lens-barrel. It is sectional drawing which shows the schematic structure in the WIDE state of a lens-barrel. It is sectional drawing which shows the schematic structure in the TELE state of a lens-barrel. It is sectional drawing (a) which shows the relationship between a fixed cylinder and a 1st cam cylinder, and the expanded view (b) which shows the shape of the female helicoid of the inner surface of a fixed cylinder. Sectional view (a) showing the relationship between the first lens group frame and the first cam cylinder, and the shape of the cam groove formed on the outer surface of the first cam cylinder on the object side with respect to the flange portion. It is an expanded view (b) shown. Sectional drawing (a) which shows the relationship between a 1st cam cylinder and a 2nd cam cylinder, and the rectilinear guide groove formed in the inner surface other than the inner surface corresponding to a flange part among the inner surfaces of a 1st cam cylinder It is an expanded view (b) which shows a shape. It is an enlarged view of FIG.8 (b). It is sectional drawing (a) which shows the relationship between a 2nd cam cylinder and a 2nd lens group frame, and an expanded view which shows the shape of the cam groove of the inner surface of a 2nd cam cylinder. It is sectional drawing (a) which shows the relationship between a 2nd cam cylinder and a key cylinder, and the expanded view which shows the shape of the female helicoid and the notch | incision part of the outer surface of a key cylinder.

Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.
(Embodiment)
FIGS. 1 and 2 are exploded views showing components constituting a lens barrel as a configuration of an embodiment to which the present invention is applied. FIGS. 3 to 5 show the lens barrel in the PARK state, the WIDE state, and the TELE state. 1 shows a fixed configuration, 1 is a fixed barrel, 2 is a movable barrel, 3 is a first lens group frame, 4 is a first cam barrel, 5 is a second cam barrel, 6 is a key barrel, and 7 is a second lens. It is a group frame.

As shown in the figure, the fixed cylinder 1 has a substantially cylindrical shape centered on the optical axis, and inside the movable cylinder 2, the first lens group frame 3, the first cam cylinder 4, and the second cam. The cylinder 5, the key cylinder 6, the second lens group frame 7, and the lens are included in this order.
In the following description, of the orthogonal directions from the optical axis, the direction away from the optical axis is the outside, and the approaching direction is the inside.

The fixed cylinder 1 is formed on the inner surface thereof at three positions at intervals of 120 ° parallel to the optical axis with the straight guide grooves 11 having open portions at the image end portions, and the female helicoid 12 shown in FIG. Are formed at three positions at intervals of 120 ° with the opening portions ahead of the TELE end of the object side end portion (where the first cam cylinder 4 is rotated more than 138 °).
In the rectilinear guide groove 11, the rectilinear protrusions 61 formed at three positions at 120 ° intervals extending from the key cylinder 6 and the rectilinear protrusions 21 extending from the outside of the movable cylinder 2 are engaged. To do.
Male helicoids 41 formed at three locations on the outer surface of the first cam cylinder 4 at intervals of 120 ° are engaged with the female helicoid 12.

The moving cylinder 2 is formed with three straight-ahead projections 21 at 120 ° intervals on the image side end of the outer surface. Further, on the inner side surface, the rectilinear guide grooves 22 are formed at three positions at intervals of 120 ° parallel to the optical axis in a state having an open portion at the image side end portion, and further, closer to the image side of the inner side surface, The fixing groove 23 is formed orthogonal to the optical axis direction and parallel to the circumferential direction.
The rectilinear projection 21 is engaged with the rectilinear guide groove 11 of the fixed cylinder 1.
The fixing groove 23 engages with a fixing rib 43 formed on a flange portion 42 protruding to the outer side of the first cam cylinder 4 on the outer side of the image side.
The rectilinear guide grooves 22 are engaged with rectilinear protrusions 31 formed at three positions at 120 ° intervals on the image side end of the outer surface of the first lens group frame 3.

The first lens group frame 3 has a cylindrical shape, and a lens barrier 36, a lens holding frame 37, and a lens group 38 are fixed to a surface orthogonal to the optical axis on the object side from the object side.
The first lens group frame 3 has rectilinear protrusions 31 formed at three positions at 120 ° intervals at the image side end of the outer surface, and a cam follower 32 on the inner surface of the rectilinear protrusion 31.
The rectilinear protrusion 31 engages with the rectilinear guide groove 22 of the movable cylinder 2.
The cam follower 32 engages with a cam groove 44 formed on the outer surface of the first cam cylinder 4.

The first cam cylinder 4 has a flange portion 42 that protrudes further outward, with the image side end of the outer surface having a larger diameter on the surface orthogonal to the optical axis than the object side.
On the object side of the outer surface of the first cam cylinder 4 with respect to the flange portion 42, cam grooves 44 shown in FIG. 7 are formed at three locations at intervals of 120 °.
The cam follower 32 on the inner surface of the first lens group frame 3 is engaged with the cam groove 44.

Further, a gear having a central angle equal to the rotation angle of the first cam cylinder 4 in an arc shape covering the outer surface of the image side end portion in the circumferential direction on the flange portion 42 of the outer surface of the first cam cylinder 4. Part 45.
On the object side of the gear portion 45, male helicoids 41 are formed at three locations at intervals of 120 ° with the tip facing outward.
Furthermore, protrusions are projected outwardly at three locations at 120 ° intervals on the step portion which is closer to the object side than the male helicoid 41 and faces in the optical axis direction at the boundary between the flange portion 42 and the outer surface on the object side. The fixing rib 43 is directed.

The male helicoid 41 is engaged with the female helicoid 12 of the fixed cylinder 1.
The fixed rib 43 engages with the fixed groove 23 of the movable cylinder 2.
Further, the flange portion 42 has recesses 46 at three positions at intervals of 120 °, and is connected to the side surface on the object side of the flange portion 42 in the outer side surface of the first cam cylinder 4.
Accordingly, by forming a part of the cam groove 44 inside the recess 46, it is possible to ensure the length of the cam groove 44 in the optical axis direction.

The inner surface of the first cam cylinder 4 has different inner diameters between the portion corresponding to the flange portion 42 on the outer surface and the inner surface on the object side, and the inner diameter of the portion corresponding to the flange portion 42 on the outer surface is It is larger than the inner surface located on the object side.
Further, on the inner side surface of the inner side surface located on the object side with respect to the portion corresponding to the flange portion 42 on the outer side surface, the straight guide groove 47 shown in FIG. 8 has an open portion at the image side end portion. It is formed parallel to the optical axis.

The rectilinear guide groove 47 is extended in a state where the image side end portion is bent by 90 ° in the circumferential direction and the image side end portion is opened. This is equal to the amount of movement in the circumferential direction when the tube 4 rotates 13 °.
The straight advancement groove 51 on the outer side surface of the second cam cylinder 5 is engaged with the straight advance guide groove 47 described above.

A fixing groove 48 parallel to the circumferential direction is formed on the inner side of the first cam cylinder 4 near the image side of the inner side having a large inner diameter corresponding to the flange portion 42 on the outer side.
On the image side wall of the fixed groove 48, open portions 49 are provided at three positions at intervals of 120 °.
A fixing rib 62 on the outer surface of the key cylinder 6 is engaged with the fixing groove 48.

The second cam cylinder 5 is provided with three straight advancement projections 51 at 120 ° intervals at the image side end of the outer surface.
Further, male helicoids 52 are formed at three positions at intervals of 120 ° at the image side end of the inner surface.
The rectilinear protrusion 51 is engaged with a rectilinear guide groove 47 formed on the inner surface of the first cam cylinder 4.
The male helicoid 52 is engaged with a female helicoid 63 formed on the outer surface of the key cylinder 6.

A cam groove 53 shown in FIG. 10 is formed on the inner surface of the second cam cylinder 5.
A cam follower 72 on the outer surface of the image side end of the straight projection 71 of the second lens group frame 7 is engaged with the cam groove 53.

In the key cylinder 6, on the object side, incisions 64 shown in FIG. 11 are formed at three positions at intervals of 120 ° through the side surface.
The cut portion 64 is open on the object side but closed on the image side.
A band-like straight projection 71 formed on the outer surface of the second lens group frame 7 passes through and engages with the above-described cut portion 64.

A female helicoid 63 shown in FIG. 11 is formed on the outer surface of the key cylinder 6.
The female helicoid 63 has an opening ahead of the TELE end (where the first cam cylinder 4 is rotated more than 138 °), and the circumferential width is larger than the circumferential width of the cut portion 64. Is also formed large.
The female helicoid 63 engages with the male helicoid 52 on the inner surface of the second cam cylinder 5.

In addition, a rectilinear projection 61 is formed at the image side end of the outer surface of the key cylinder 6.
The rectilinear protrusion 61 engages with the rectilinear guide groove 11 formed on the inner surface of the fixed cylinder 1.
Further, a fixing rib 62 is formed in the middle of the rectilinear protrusion 61.
The fixing rib 62 engages with the fixing groove 48 at the image side end portion of the inner surface of the first cam cylinder 4.

The second lens group frame 7 holds a lens 76 on the inner side, and on the outer surface, a belt-like straight projection 71 parallel to the optical axis, and a tip protruding toward the object side of the straight projection 71. The cam followers 72 are formed at intervals of 120 [deg.] With their tips directed outward from the portion.
The rectilinear projection 71 engages with the notch 64 of the key cylinder 6 while penetrating.
The cam follower 72 engages with a cam groove 53 formed on the inner surface of the second cam cylinder 5.

  Next, details of each groove formed in the fixed cylinder 1, the first cam cylinder 4, the second cam cylinder 5, and the key cylinder 6 will be described.

As shown in FIG. 6, the female helicoid 12 on the inner surface of the fixed cylinder 1 is formed in a range of a central angle of 138 ° among the side surfaces of the fixed cylinder 1.
The female helicoid 12 is formed in a diagonal direction from 0 ° to 60 ° linearly from the image side to the object side when the inner surface of the fixed cylinder 1 is developed as a plane, and from 60 ° to 138 °. Is formed as a linear groove orthogonal to the optical axis and parallel to the circumferential direction.

  Here, at 0 °, the lens barrel is in the PARK state shown in FIG. 3, at 60 °, the lens barrel is in the WIDE state shown in FIG. 4, and at 138 °, the lens barrel is TELE shown in FIG. State.

As shown in FIG. 7, the cam groove 44 on the outer surface of the first cam cylinder 4 is formed in a range of a central angle of 138 ° on the side surface of the first cam cylinder 4.
The cam groove 44 is linearly formed from the image side to the object side from 0 ° to 60 ° when the outer surface of the first cam cylinder 4 is developed as a flat surface, and once from 60 ° to 138 °, the cam groove 44 is temporarily moved to the image side. A groove is formed so as to move toward the object side again after moving.

  Here, at 0 °, the lens barrel is in the PARK state, at 60 °, the lens barrel is in the WIDE state, and at 138 °, the lens barrel is in the TELE state.

As shown in FIGS. 8 and 9, the rectilinear guide groove 47 on the inner surface of the first cam cylinder 4 is formed in parallel with the optical axis when the inner peripheral surface of the first cam cylinder 4 is developed as a plane. It is a groove.
Further, a groove 47L is extended in a direction perpendicular to the image side end of the straight guide groove 47 in the rotation direction when the first cam cylinder 4 is shifted from the PARK state to the WIDE state, and the extended groove portion. The length of 47L corresponds to the amount of movement in the circumferential direction when the first cam cylinder 4 rotates 13 °.

Here, when the straight projection 51 of the second cam cylinder 5 is positioned at the end of the extended groove 47L, the lens barrel is in the PARK state.
From 13 ° to 60 °, which is the WIDE state, the straight projection 51 is located at an inflection point between the groove 47 parallel to the optical axis and the groove 47L orthogonal to the optical axis.
Further, from 60 ° to 138 °, the rectilinear protrusion 51 moves the rectilinear guide groove 47 parallel to the optical axis from the image side to the object side, and the rectilinear protrusion protuberance at a predetermined position near the object side of the rectilinear guide groove 47. When 51 is present, the TELE state is entered.

As shown in FIG. 10, the cam groove 53 on the inner side surface of the second cam cylinder 5 is formed in a range of a central angle of 125 ° on the side surface of the second cam cylinder 5.
The cam groove 53 is linearly formed from the object side to the image side from 0 ° to 47 ° when the inner surface of the second cam cylinder 5 is developed and viewed as a plane, and from 47 ° to 125 ° the object from the image side Grooves are formed on the side, approaching the image side most at 47 ° and approaching the object side most at 125 °.

  Here, at 0 °, the lens barrel is in the PARK state, at 47 °, the lens barrel is in the WIDE state, and at 125 °, the lens barrel is in the TELE state.

As shown in FIG. 11, the female helicoid 63 on the outer surface of the key cylinder 6 is formed in a range of a central angle of 125 ° on the side surface of the key cylinder 6.
The female helicoid 63 has a groove 63L linearly formed in parallel to the circumferential direction orthogonal to the optical axis from 0 ° to 47 ° when the outer surface of the key cylinder 6 is developed as a flat surface. At 0 °, a groove is linearly formed in an oblique direction from the image side to the object side.

  Here, at 0 °, the lens barrel is in the PARK state, at 47 °, the lens barrel is in the WIDE state, and at 125 °, the lens barrel is in the TELE state.

  Next, details of driving of the lens barrel will be described.

“Rotation angle of first cam cylinder 4 0-13 °”
The drive of a motor (not shown) is transmitted to the first cam cylinder 4 through the pinion and the gear portion 45, whereby the first cam cylinder 4 starts rotating in the circumferential direction around the optical axis. At this time, when the rotation angle of the first cam cylinder 4 is between 0 and 13 °, the first cam cylinder 4 engages the female helicoid 12 of the fixed cylinder 1 with the male helicoid 41, and the helicoids 12 and 41 are screwed together. It moves in the direction of the optical axis.

Since the movable cylinder 2 is engaged with the fixing rib 43 of the first cam cylinder 4 through the fixing groove 23 on the inner surface thereof, the movable cylinder 2 moves integrally with the first cam cylinder 4 in the optical axis direction. However, at the same time, since the rectilinear protrusion 21 of the moving cylinder 2 is engaged with the rectilinear guide groove 11 of the fixed cylinder 1, the moving cylinder 2 does not rotate.
Therefore, the moving cylinder 2 moves in the optical axis direction integrally with the first cam cylinder 4 but does not rotate in the circumferential direction at all.

Since the first lens group frame 3 engages the cam follower 32 on the inner side surface thereof with the cam groove 44 on the outer side surface of the first cam cylinder 4, the cam groove 44 is formed in the cam follower 32 when the first cam cylinder 4 rotates. The driving force from is transmitted. However, at the same time, since the straight projection 31 of the first lens group frame 3 is engaged with the straight guide groove 22 of the movable cylinder 2, the first lens group frame 3 does not rotate.
Therefore, since the force in the circumferential direction of the driving force applied to the first lens group frame 3 by the first cam cylinder 4 is suppressed by the rectilinear guide groove 22, the first lens group frame 3 moves in the optical axis direction. Moves but does not rotate at all in the circumferential direction.

The key cylinder 6 is not rotated in the circumferential direction because the linearly projecting protrusion 61 on the outer side surface thereof is engaged with the linear guide groove 11 on the inner side surface of the fixed cylinder 1. However, at the same time, the fixing rib 62 formed in the middle of the straight projection 61 is engaged with the fixing groove 48 on the inner surface of the first cam cylinder 4, so that the light is integrated with the first cam cylinder 4. Move in the axial direction.
Therefore, the key cylinder 6 moves integrally with the first cam cylinder 4 in the optical axis direction, but does not rotate at all in the circumferential direction.

In the second cam cylinder 5, the rectilinear projection 51 on the outer surface is engaged with the rectilinear guide groove 47 on the inner surface of the first cam cylinder 4. However, since the rectilinear protrusion 51 moves in the groove 47 </ b> L parallel to the circumferential direction of the rectilinear guide groove 47, the driving force due to the rotation of the first cam cylinder 4 is not transmitted to the second cam cylinder 5.
When the lens barrel is assembled, the second cam cylinder 5 is sandwiched between the first cam cylinder 4 and the key cylinder 6, and the first cam cylinder 4 and the key cylinder 6 are integrated in the optical axis direction. Since the second cam cylinder 5 is engaged with the first cam cylinder 4 by the straight projection 51 and is engaged with the key cylinder 6 by the male helicoid 52, the key cylinder 6 and the first cam cylinder are engaged. As 4 moves in the optical axis direction, it moves in the optical axis direction.
When the rotation angle of the first cam cylinder 4 reaches 13 °, the rectilinear projection 51 reaches the inflection point of the rectilinear guide groove 47.

In the second lens group frame 7, the rectilinear protrusion 71 on the outer surface is engaged with the notch 64 of the key cylinder 6, and the cam follower 72 at the image side tip of the rectilinear protrusion 71 is connected to the second cam cylinder 5. The cam groove 53 on the inner peripheral surface is engaged. However, since the second cam cylinder 5 does not rotate in the circumferential direction, the cam groove 53 does not bias the cam follower 72.
Therefore, the second lens group frame 7 moves together with the key cylinder 6.

“Rotation angle 13-60 ° of first cam cylinder 4”
The drive of the motor is transmitted to the first cam cylinder 4 through the pinion and the gear portion 45, whereby the first cam cylinder 4 starts to rotate in the circumferential direction around the optical axis. At this time, when the rotation angle of the first cam cylinder 4 is between 13 and 60 °, the first cam cylinder 4 engages the male helicoid 41 with the female helicoid 12 of the fixed cylinder 1, and It moves in the optical axis direction by screwing.
When the rotation angle of the first cam cylinder 4 reaches 60 °, the male helicoid 41 is located closest to the object side of the female helicoid 12.

The moving cylinder 2 moves in the optical axis direction integrally with the first cam cylinder 4 because the fixing rib 43 of the first cam cylinder 4 is engaged with the fixing groove 23 on the inner surface thereof. However, at the same time, since the rectilinear protrusion 21 of the moving cylinder 2 is engaged with the rectilinear guide groove 11 of the fixed cylinder 1, the moving cylinder 2 does not rotate.
Therefore, the moving cylinder 2 moves in the optical axis direction integrally with the first cam cylinder 4 but does not rotate in the circumferential direction at all.

Since the first lens group frame 3 engages the cam follower 32 on the inner side surface thereof with the cam groove 44 on the outer side surface of the first cam cylinder 4, the cam groove 44 is formed in the cam follower 32 when the first cam cylinder 4 rotates. Due to this, the driving force is transmitted. However, at the same time, since the straight projection 31 of the first lens group frame 3 is engaged with the straight guide groove 22 of the movable cylinder 2, the first lens group frame 3 does not rotate.
Therefore, since the force in the circumferential direction of the driving force applied to the first lens group frame 3 by the first cam cylinder 4 is suppressed by the rectilinear guide groove 22, the first lens group frame 3 moves in the optical axis direction. It only moves and does not rotate at all in the circumferential direction.
When the rotation angle of the first cam cylinder 4 reaches 60 °, the first lens group frame 3 is in the WIDE state.

The key cylinder 6 does not rotate in the circumferential direction because the linearly projecting protrusion 61 on the outer surface thereof is engaged with the rectilinear guide groove 11 on the inner surface of the fixed cylinder 1. However, at the same time, the fixing rib 62 formed in the middle of the straight projecting portion 61 is engaged with the fixing groove 48 on the inner surface of the first cam cylinder 4. Move in the axial direction.
Therefore, the key cylinder 6 moves integrally with the first cam cylinder 4 in the optical axis direction, but does not rotate at all in the circumferential direction.

The second cam cylinder 5 has a rectilinear projection 51 on its outer surface engaged with a rectilinear guide groove 47 on the inner surface of the first cam cylinder 4, and when the rotation angle of the first cam cylinder 4 is 13 °. Thus, the rectilinear protrusion 51 is located at the inflection point of the rectilinear guide groove 47. For this reason, when the first cam cylinder 4 is rotated by 13 ° or more, the rectilinear protrusion 51 pushes the inner wall of the rectilinear guide groove 47, whereby the second cam cylinder 5 starts to rotate.
When the second cam cylinder 5 starts to rotate, the male helicoid 52 on the inner surface of the second cam cylinder 5 moves on the female helicoid 63 on the outer surface of the key cylinder 6. However, since the portion of the female helicoid 63 with which the male helicoid 52 engages is a groove parallel to the circumferential direction while the first cam cylinder 4 rotates from 13 ° to 60 °, the second cam cylinder 5 The cam cylinder 4 and the key cylinder 6 do not move relative to each other in the optical axis direction but move together in the optical axis direction.
When the rotation angle of the first cam cylinder 4 reaches 60 °, the rotation angle of the second cam cylinder 5 is 47 °, and the straight projection 51 has a rotation angle of 13 to Between 60 °, the straight guide groove 47 does not move from the inflection point and stays there.

The second lens group frame 7 includes a cam follower 72 having a rectilinear projection 71 on the outer surface thereof engaged with a notch 64 of the key cylinder 6, and a cam follower 72 with the distal end directed outward from the image side tip of the rectilinear projection 71. The cam groove 53 on the inner peripheral surface of the second cam cylinder 5 is engaged. For this reason, when the second cam cylinder 5 rotates in the circumferential direction, the cam groove 53 urges the cam follower 72, and at the same time, the cut portion 64 of the key cylinder 6 engages with the straight projection 71. The rotation of the second lens group frame 7 in the circumferential direction is restricted, and the second lens group frame 7 moves only in the optical axis direction.
When the rotation angle of the first cam cylinder 4 reaches 60 °, the rotation angle of the second cam cylinder 5 is 47 °, and the second lens group frame 7 is in the WIDE state.

“Rotation angle of first cam cylinder 4 is 60 to 138 °”
The drive of the motor is transmitted to the first cam cylinder 4 through the pinion and the gear portion 45, whereby the first cam cylinder 4 starts to rotate in the circumferential direction around the optical axis. At this time, when the rotation angle of the first cam cylinder 4 is between 60 and 138 °, the male helicoid 41 of the first cam cylinder 4 moves in the groove parallel to the circumferential direction of the female helicoid 12 of the fixed cylinder 1. The first cam cylinder 4 does not move in the optical axis direction, but only rotates in the circumferential direction.
When the rotation angle of the first cam cylinder 4 reaches 138 °, the male helicoid 41 of the first cam cylinder 4 is the most open in the groove parallel to the circumferential direction of the front end of the female helicoid 12 of the fixed cylinder 1. It is located at the near TELE end.

The moving cylinder 2 moves in the optical axis direction integrally with the first cam cylinder 4 because the fixing rib 43 of the first cam cylinder 4 is engaged with the fixing groove 23 on the inner surface thereof. However, at the same time, since the rectilinear protrusion 21 of the moving cylinder 2 is engaged with the rectilinear guide groove 11 of the fixed cylinder 1, the moving cylinder 2 does not rotate.
Therefore, when the rotation angle of the first cam cylinder 4 is 60 ° or more, the first cam cylinder 4 does not move in the optical axis direction, but only rotates in the circumferential direction. It does not move in the circumferential direction, and is stationary on the spot.

Since the cam follower 32 on the inner surface of the first lens group frame 3 is engaged with the cam groove 44 on the outer surface of the first cam cylinder 4, the cam follower 32 has a cam groove on the rotation of the first cam cylinder 4. The driving force is transmitted by 44. However, at the same time, since the straight projection 31 of the first lens group frame 3 is engaged with the straight guide groove 22 of the movable cylinder 2, the first lens group frame 3 does not rotate.
Therefore, since the force in the circumferential direction of the driving force applied to the first lens group frame 3 by the first cam cylinder 4 is suppressed by the rectilinear guide groove 22, the first lens group frame 3 moves in the optical axis direction. Moves but does not rotate at all in the circumferential direction.
When the rotation angle of the first cam cylinder 4 reaches 138 °, the first lens group frame 3 is in the TELE state.

The key cylinder 6 does not rotate in the circumferential direction because the rectilinear projection 61 on the outer surface engages with the rectilinear guide groove 11 on the inner surface of the fixed cylinder 1. However, at the same time, the fixing rib 62 formed in the middle of the straight projecting portion 61 is engaged with the fixing groove 48 on the inner surface of the first cam cylinder 4. Move in the axial direction.
Therefore, when the rotation angle of the first cam cylinder 4 is 60 ° or more, the first cam cylinder 4 does not move in the optical axis direction, but only rotates in the circumferential direction. However, it does not rotate in the circumferential direction and is stationary on the spot.

The second cam cylinder 5 has a rectilinear projection 51 on its outer surface engaged with a rectilinear guide groove 47 on the inner surface of the first cam cylinder 4, and when the rotation angle of the first cam cylinder 4 is 60 °. Thus, the rectilinear protrusion 51 is located at the inflection point of the rectilinear guide groove 47.
When the rotation angle of the first cam cylinder 4 exceeds 60 °, the male helicoid 52 on the inner surface of the second cam cylinder 5 has a groove portion having a component in the optical axis direction of the female helicoid 63 on the outer surface of the key cylinder 6. The helicoids 52 and 63 are engaged with each other to move in the optical axis direction, and the circumferential rotation is performed integrally with the first cam cylinder 4.
When the rotation angle of the first cam cylinder 4 reaches 138 °, the rotation angle of the second cam cylinder 5 becomes 125 °, and the straight movement projection 51 is located at the TELE position closer to the predetermined object side of the straight movement guide groove 47. Existing.

The second lens group frame 7 has a rectilinear protrusion 71 on the outer surface thereof engaged with a notch 64 of the key cylinder 6, and a cam follower 72 directed outward from the image side tip of the rectilinear protrusion 71. The cam groove 53 on the inner peripheral surface of the second cam cylinder 5 is engaged. For this reason, when the second cam cylinder 5 rotates in the circumferential direction, the cam groove 53 transmits a driving force to the cam follower 72, and at the same time, the cut portion 64 of the key cylinder 6 engages with the straight projection 71. Thus, by restricting the rotation of the second lens group frame 7 in the circumferential direction, the second lens group frame 7 moves in the optical axis direction.
When the rotation angle of the first cam cylinder 4 reaches 138 °, the rotation angle of the second cam cylinder 5 is 125 °, and the second lens group frame 7 is in the TELE state.

As described above, in the rectilinear guide groove 47 on the inner surface of the first cam cylinder 4 that supports the second cam cylinder 5 so as to linearly advance in the optical axis direction, it is orthogonal to the optical axis from the image side end of the rectilinear guide groove 47. Thus, the groove portion 47L parallel to the circumferential direction corresponds to the difference between the rotation angles of the first cam cylinder 4 and the second cam cylinder 5 in the rotation direction of the cam cylinders 4 and 5 for shifting from the PARK state to the WIDE state. It is extended by the length of the arc with the angle at the center angle.
Accordingly, it is possible to suppress the overlapping of the cam grooves 53 of the second cam cylinder 5 by reducing the rotation angle of the second cam cylinder 5 while sufficiently securing the rotation angle of the first cam cylinder 4. Become.

When the male helicoid 52 of the second cam cylinder 5 shifts from the PARK state to the WIDE state in the female helicoid 63 on the outer surface of the key cylinder 6 engaged so as to drive the second cam cylinder 5 in the optical axis direction. A groove portion 63L passing through is formed in a direction perpendicular to the optical axis and parallel to the circumferential direction.
Thereby, it is possible to secure a sufficient amount of movement in the optical axis direction when the second cam cylinder 5 is shifted from the WIDE state to the TELE state, whereby only the second lens group frame 7 is in the optical axis direction. Accordingly, the cam groove 53 for driving the second lens group frame 7 can be accommodated in the side surface of the second cam cylinder 5.

  The operation of each part is summarized as follows.

The fixed cylinder 1 does not move in the optical axis direction and does not rotate in the circumferential direction.
The movable cylinder 2, the first lens group frame 3, the key cylinder 6, and the second lens group frame 7 move only in the optical axis direction.
The first cam cylinder 4 moves in the optical axis direction and also rotates in the circumferential direction. The rotation angle is 138 °.
The second cam cylinder 5 moves in the optical axis direction and also rotates in the circumferential direction. The rotation angle is 125 °.

The gear unit 45 receives the drive of the motor, and the first cam cylinder 4 rotates.
Only the first cam cylinder 4 rotates by 13 °.
The rectilinear projection 51 of the second cam cylinder 5 starts to urge the inner wall of the rectilinear guide groove 47 of the first cam cylinder 4.
The second cam cylinder 5 also starts rotating due to the urging from the first cam cylinder 4.

When the first cam cylinder 4 is rotated, the first cam cylinder 4 is moved in the optical axis direction by screwing of the helicoids 12 and 41 with the fixed cylinder 1.
When the rotation angle of the first cam cylinder 4 exceeds 60 °, the movement of the first cam cylinder 4 in the optical axis direction stops.
When the second cam cylinder 5 rotates, the second cam cylinder 5 moves in the optical axis direction by screwing the helicoids 52 and 63 with the key cylinder 6.
When the rotation angle of the second cam cylinder 5 exceeds 47 °, the movement of the second cam cylinder 5 in the optical axis direction starts.

The moving cylinder 2 moves integrally with the first cam cylinder 4 in the optical axis direction by the fixing groove 23 and the fixing rib 43.
The rectilinear protrusion 21 is engaged with the rectilinear guide groove 11 to restrict the rotation of the movable cylinder 2 in the circumferential direction.

The first lens group frame 3 moves in the optical axis direction along the cam groove 44 of the first cam cylinder 4.
The rectilinear protrusion 31 is engaged with the rectilinear guide groove 22 to restrict the rotation of the first lens group frame 3 in the circumferential direction.

The key cylinder 6 moves integrally with the first cam cylinder 4 in the optical axis direction by the fixing groove 48 and the fixing rib 62.
The rectilinear projection 61 is engaged with the rectilinear guide groove 11 to restrict the rotation of the movable cylinder 2 in the circumferential direction.

The second lens group frame 7 moves in the optical axis direction along the cam groove 53 of the second cam cylinder 5.
The rectilinear protrusion 71 is engaged with the notch 64 to restrict the rotation of the second lens group frame 7 in the circumferential direction.

  As described above, according to the lens barrel drive mechanism of the embodiment, since the rotation angles of the first cam cylinder 4 and the second cam cylinder 5 are different, a simple and small lens barrel having a large amount of movement in the optical axis direction is provided. Can do.

  Specifically, it corresponds to the difference in rotational angle between the first cam cylinder 4 and the second cam cylinder 5 at the image side end portion of the rectilinear guide groove 47 of the first cam cylinder 4 with which the second cam cylinder 5 is engaged. Grooves 47L that are orthogonal to the optical axis and parallel to the circumferential direction are extended by an angle.

  Therefore, since the second cam cylinder 5 is short in the circumferential direction, if the same rotation angle as that of the first cam cylinder 4 is provided, the plurality of cam grooves 44 and 53 formed on the side surfaces overlap each other. On the other hand, by making the rotation angle of the second cam cylinder 5 smaller than the rotation angle of the first cam cylinder 4, it is possible to suppress the cam grooves 53 of the second cam cylinder 5 from overlapping.

  Then, the female helicoid 63 of the key cylinder 6 with which the second cam cylinder 5 is engaged is orthogonal to the optical axis so as not to move the second cam cylinder 5 in the optical axis direction between the PARK state and the WIDE state. It is formed as a groove 63L parallel to.

  Therefore, at the time of zooming from the WIDE state to the TELE state, the width of the cam groove 53 in the optical axis direction is set within the side surface of the second cam cylinder 5 while ensuring the amount of movement of the second lens group frame 7 in the optical axis direction. Can fit in.

(Modification)
In the above embodiment, a groove portion perpendicular to the optical axis and parallel to the circumferential direction is extended at the image side end of the straight guide groove of the first cam cylinder, and the female helicoid of the key cylinder is orthogonal to the optical axis. However, the present invention is not limited to this, and the first cam cylinder and the second cam cylinder need only have different rotation angles.
Further, the shape of the engaging cam and the like are arbitrary, and it is needless to say that other specific detailed structures can be appropriately changed.

DESCRIPTION OF SYMBOLS 1 Fixed cylinder 11 Rectilinear guide groove 12 Female helicoid 2 Moving cylinder 21 Protrusion part 22 for rectilinear advance Guide groove 23 Fixed groove 3 First lens group frame 31 Protrusion part 32 Cam follower 36 Lens barrier 37 Lens holding frame 38 Lens group 4th One cam cylinder 41 Male helicoid 42 Flange part 43 Fixed rib 44 Cam groove 45 Gear part 46 Recess 47 Straight guide groove 47L Groove part 48 parallel to the circumferential direction Fixed groove 49 Open part 5 Second cam cylinder 51 Protrusion part 52 for straight advance Male helicoid 53 Cam groove 6 Key cylinder 61 Protrusion part 62 for rectilinear movement 63 Fixing rib 63 Female helicoid 63L Groove part 64 parallel to the circumferential direction Incision part 7 Second lens group frame 71 Protrusion part 72 for rectilinear advance Cam follower 76 Lens

Claims (3)

A first cam barrel that receives rotational driving and moves in the direction of rotation and optical axis;
A first lens group frame that holds the subject-side lens group and engages with the outer peripheral side of the first cam cylinder and moves in the optical axis direction;
A second cam cylinder that engages the inner peripheral side of the first cam cylinder and moves in the direction of rotation and optical axis;
A lens barrel drive mechanism comprising: a second lens group frame that holds an imaging element side lens and engages with an inner peripheral side of the second cam cylinder and moves in an optical axis direction;
A lens barrel drive mechanism characterized in that the first cam cylinder and the second cam cylinder have different rotation angles. At the image sensor side end of the straight guide groove provided on the first cam cylinder and engaged with the second cam cylinder,
The groove portion orthogonal to the optical axis and parallel to the circumferential direction is extended by an angle corresponding to a difference in rotation angle between the first cam cylinder and the second cam cylinder. Lens barrel drive mechanism. A key cylinder that is engaged with the inner peripheral side of each of the first cam cylinder and the second cam cylinder and moves in the optical axis direction integrally with the first cam cylinder;
A female helicoid provided on the key cylinder and engaged with the second cam cylinder is
Between the retracted state of the lens barrel and the ready-to-shoot state, the second cam barrel is formed as a groove portion orthogonal to the optical axis and parallel to the circumferential direction so as not to move in the optical axis direction. Item 3. The lens barrel drive mechanism according to Item 1 or 2.

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