JP3482738B2 - Lens barrel - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens barrel, and more particularly to a lens barrel whose focal length can be changed over a wide range.

[0002]

2. Description of the Related Art Conventionally, in this type of lens barrel, at least a part of the optical system, in particular, an optical system located at the frontmost side of the lens barrel (hereinafter referred to as "first lens group") is arranged in the optical axis direction. The focal length is changed by moving the lens back and forth to adjust the magnification of the image seen through the lens barrel. In such a lens barrel, the wider the adjustable magnification range, the longer the distance the optical system moves. That is, the focal length range is 28 mm more than that of a lens barrel having a 35 mm to 70 mm range.
The lens barrel having a size of mm to 80 mm has a larger degree of expansion and contraction in its outer shape in the optical axis direction. Also, the range of focal length is 3
70mm to 10mm more than a lens barrel of 5mm to 70mm
The lens barrel of 5 mm, that is, the lens barrel having a large focal length and a high magnification even if the amount of change in the focal length is the same, is the amount of movement of the optical system, especially the movement of the first lens group. The amount is large. So far, this type of lens barrel has been mainly produced with a low-magnification lens barrel in which the movement amount of the lens group is small and a compact outer shape can be obtained. On the other hand, in recent years, there has been an increasing demand for a lens barrel capable of changing the focal length over a wide range from low magnification to high magnification.

[0003]

However, in the above-mentioned conventional lens barrel of this type, if the range in which the focal length can be adjusted is widened, the movement amount of the first lens group inevitably increases as described above. growing. Therefore, when the first lens group is extended to the front of the lens barrel, the rear end of the support member (lens moving frame) that supports the first lens group is located in front of the front end of the outer cylinder part, and the support member and the outer cylinder part There will be an opening between them. In this opening, the inside of the lens barrel can be seen from the outside, which causes a problem that the appearance of the lens barrel is extremely deteriorated. On the other hand, in order to prevent the occurrence of the above-mentioned opening, if the supporting member that supports the first lens group and the outer cylinder portion of the lens barrel that accommodates the supporting member are lengthened in the optical axis direction, the lens group is moved to the lens barrel. When you pull it back,
There is a problem that the length of the lens barrel in the optical axis direction becomes long.

Therefore, an object of the present invention is to solve the above-mentioned problems and to change the focal length in a wide range, and to change the focal length in the optical axis direction when the lens group is pulled rearward of the lens barrel. It is an object of the present invention to provide a lens barrel that has a short length and does not lose its appearance when the lens group is extended to the front of the lens barrel.

[0005]

[0006]

[Means for Solving the Problems]
In the invention according to claim 1 , the outer cylinder portion (13, 100) is provided.
And a large diameter portion (21) arranged inside the outer tubular portion (13, 100) and a small diameter portion (25) located inside the large diameter portion (21), centered on the optical axis. A cam ring (20) that is movable in the circumferential direction and the optical axis direction, and a part of the optical system are supported, and relatively move in the optical axis direction to the inner peripheral surface of the large diameter portion (21) of the cam ring (20) at the rear part of the outer peripheral surface. A lens moving frame (30) which is engaged with the cam ring, and a cam ring drive mechanism (17, 29) for driving the cam ring (20) in the optical axis direction;
A lens moving frame driving mechanism (32, 56, 27, 54, 17, 29) for moving the lens moving frame (30) relative to the cam ring (20) in conjunction with the cam ring (20). A lens barrel for changing the focal length by moving (30), the lens moving frame drive mechanism (32, 56, 27, 54, 17, 29),
The rear end of the lens moving frame (30) is the outer cylinder part (13, 100).
Lens moving frame (30) so that it is located in front of the front end of
Lens drive frame drive mechanism (32, 56, 2
7, 54, 17, 29), the tip of the large diameter portion (21) of the cam ring (20) is always located in front of the rear end of the lens moving frame (30), and the cam ring drive mechanism (17, 2).
9), the cam ring (20) the rear end of the large-diameter portion (21) is out repeatedly the cam ring (20) to be located behind the front end of the outer tube portion (13,100) of always the lens movement
The opening formed between the frame and the outer cylinder is shielded from light .

[0007] The invention according to claim 2 is the lens barrel according to claim 1, the lens moving frame (30) is the inner surface of the large diameter portion (21) of the cam ring (20), or the lens moves With respect to the cam ring (20), the rectilinear groove (22) provided on one side of the outer peripheral surface of the frame (30) and parallel to the optical axis and the projection (33) fitted into the rectilinear groove provided on the other side. It is characterized by being guided straight ahead. The invention according to claim 3 is the lens barrel according to claim 1 , wherein the lens moving frame (30) includes a large diameter portion (2) of the cam ring (20).
1) has a cylindrical portion (31) to be housed in or paid out, and the lengths of the cylindrical portion (31) and the large diameter portion (21) of the cam ring (20) in the optical axis direction are determined by the lens moving frame drive mechanism (3).
2, 56, 27, 54, 17, 29) is equal to the length for moving the lens moving frame (30) relative to the cam ring (20).

[0008]

According to the present invention, there are the following actions. (1) The cam ring drive mechanism drives the cam ring in the optical axis direction so that the large diameter portion of the cam ring covers the opening formed between the lens moving frame and the outer cylinder portion. Further, the lens moving frame drive mechanism interlocks with the cam ring to relatively move the lens moving frame with respect to the cam ring to change the focal length of the lens barrel. (2) The lens moving frame drive mechanism extends the lens moving frame so that the rear end of the lens moving frame is located in front of the front end of the outer cylindrical portion. In addition, the cam ring drive mechanism is such that the tip of the large diameter portion of the cam ring is always positioned in front of the rear end of the lens moving frame, and the rear end of the large diameter portion of the cam ring is positioned rearward of the front end of the outer tubular portion. Deliver the cam ring to.

(3) Since the protrusion moves in the optical axis direction along the straight advance groove, the lens moving frame and the cam ring relatively move only in the optical axis direction. (4) When the lens moving frame is extended from the outer cylinder portion, the cylindrical portion is extended from the large diameter portion of the cam ring. When the lens moving frame is housed in the outer cylinder part of the lens barrel, the entire cylindrical part is housed in the large diameter part of the cam ring.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a view showing an embodiment according to the present invention, and FIG. 1 (A) is a sectional view of a zoom lens barrel of this embodiment when each lens group is pulled rearward. Shows. Further, FIG. 1B is a partial side view of the key member used in this embodiment. As shown in the drawings, the present invention is directed to a fixed barrel 10, a cam ring 20, four lens moving frames 30, 4
0, 50, 60, a focus relay cylinder 70, a zoom ring 80, a focus ring 100, etc. are mainly configured.

The fixed barrel 10 is a frame for supporting the cam ring 20 and other components, and the rear portion 1 having a mount portion 12 for mounting the present lens barrel on the camera body.
1 and a large-diameter portion 13 and a medium-diameter portion 1 which are located in front of the rear portion 11 and whose central axes coincide with the optical axis of the lens barrel.
5 and 5. The large diameter portion 13 is a portion for supporting the zoom ring 80, the focus ring 100, and the like on the outer peripheral surface and the tip portion thereof. Also, the medium diameter portion 15
Is a portion for supporting the cam ring 20, the third lens group moving frame 50, etc., and is provided with a cam groove 17 and a guide groove 16 parallel to the optical axis on its inner peripheral surface. The guide groove 16 is
This is for guiding the third lens group moving frame 50 so that the rotational movement about the optical axis is prohibited and only the back-and-forth movement along the optical axis is performed when the focal length is adjusted. on the other hand,
The cam groove 17 is for defining the position of the cam ring 20 in the optical axis direction.

The cam ring 20 receives the driving force from the zoom ring 80, and the four lens moving frames 30, 40, 50,
It is for driving 60. The cam ring 20
Three annular bodies having the same central axis, that is, the large diameter portion 21,
It is composed of a medium diameter portion 24 and a small diameter portion 25. Large diameter part 21
The middle diameter portion 24 and the small diameter portion 2 at the rear end portion.
5 are connected to each other at the tip, and 1 as a whole
It is a member. Therefore, the cross section of the cam ring 20 seen in the figure has a shape in which the S-shape and the inverted S-shape face each other around the optical axis. The cam ring 20 has a small-diameter portion 25 so that the outer peripheral surface thereof fits with the inner peripheral surface of the medium-diameter portion 15 of the fixed barrel 10, and the large-diameter portion 21 and the medium-diameter portion 24 of the fixed barrel 1.
It is arranged in the lens barrel so as to be located between the large diameter portion 13 of 0 and the medium diameter portion 15.

The large diameter portion 21 of the cam ring 20 is provided with a guide groove 22 on its inner peripheral surface which is parallel to the optical axis for transmitting the rotational movement of the cam ring 20 to the first group lens moving frame 30. On the other hand, a pin 23 is installed at the rear end of the outer peripheral surface. Pin 2
The reference numeral 3 penetrates an escape groove 14 provided in the fixed barrel 10, and the tip end thereof is fitted into a guide groove 81 provided in the inner peripheral surface of the zoom ring 80 in parallel with the optical axis. As a result, the cam ring 20 receives the driving force in the rotational direction from the zoom ring 80 via the pin 23 and the guide groove 81.

The small diameter portion 25 of the cam ring 20 has three cam grooves 26, 27 and 28. The cam groove 26 is
A cam groove for defining the position of the fourth lens group moving frame 60 in the optical axis direction. The cam ring 20 and the fourth lens group moving frame 60 are engaged with each other via the cam groove 26 and the cam pin 63. On the other hand, the cam groove 27 is a cam groove for defining the position of the third lens group moving frame 50 in the optical axis direction. The cam groove 27 is fitted with the tip of a cam pin 54 that penetrates an escape groove 64 provided in the fourth lens group moving frame 60 in parallel with the optical axis. Here, the cam pin 54 is installed in the third lens group moving frame 50, and the rotational movement of the cam ring 20 is converted into a rectilinear movement in the optical axis direction by the cam groove 27 and the cam pin 54, so that the third lens group moving frame is moved. 50 is transmitted. The cam groove 28 is for defining the position of the second group lens moving frame 40 in the optical axis direction. In the cam groove 28, the cam pin 42 is provided on the outer peripheral surface of the second lens group moving frame 40 and penetrates the clearance groove 57 of the third lens group moving frame 50 and the clearance groove 65 of the fourth lens group moving frame 60. Are fitted to each other, which allows the driving force in the optical axis direction to be transmitted to the second lens group moving frame 40. Furthermore, the small diameter portion 2
5, the cam pin 29 is installed on the outer periphery of the rear end,
The cam pin 29 has a tip end portion thereof in the cam groove 17 of the fixed barrel 10.
Is fitted to. As a result, the cam ring 20 moves in the optical axis direction in the lens barrel in accordance with the shape of the cam groove 17. The cam groove 17 and the cam pin 29 correspond to the cam ring drive mechanism in the present invention.

The first group lens moving frame 30 is a frame body for positioning the first group lens L1 in the optical axis direction. The first group lens moving frame 30 supports the first group lens L1 on the inner peripheral surface of the front end portion thereof, and also the first group lens L1.
The cylindrical portion 31 is provided behind the portion supporting the. The length of the cylindrical portion 31 in the optical axis direction is equal to the length of the large diameter portion 21 of the cam ring 20, and is equal to the length of the first group lens moving frame 30 described later relative to the cam ring 20 in the optical axis direction. Further, the cylindrical portion 31 has the cam groove 3 on the inner peripheral surface.
2 and pins 33 on the outer periphery of the rear end portion. A cam pin 56 installed on the outer peripheral surface of the third lens group moving frame 50 is fitted into the cam groove 32 at its tip end.
Accordingly, when the first lens group moving frame 30 rotates, the first lens group moving frame 30 and the third lens group moving frame 50 move.
Makes relative movement in the optical axis direction. Further, the tip end of the pin 33 is fitted into the guide groove 22 of the cam ring 20. Therefore, the first group lens moving frame 30 receives the driving force in the rotation direction about the optical axis from the cam ring 20 to the first group lens moving frame 30 via the pin 33, and the optical signal is transmitted to the cam ring 20. It is possible to make relative movement smoothly in the axial direction. The cam groove 17 and the cam pin 29, the cam groove 27 and the cam pin 54, and the cam groove 3
2 and the cam pin 56 correspond to the lens moving frame drive mechanism in the present invention.

The second group lens moving frame 40 is a frame body for positioning the second group lens L2 in the optical axis direction. The second group lens moving frame 40 has a second group lens L2 on its inner peripheral surface.
And a cam pin 42 is installed on the outer peripheral surface of the rear end portion. As described above, the cam pin 42 is fitted in the cam groove 28 of the cam ring 20. Therefore, when the cam ring 20 moves straight in the optical axis direction or rotates about the optical axis, the second lens group moving frame 40 is driven in the optical axis direction via the cam groove 28 and the cam pin 42. .

The third group lens moving frame 50 is a frame body for positioning the third group lens L3 in the optical axis direction, and is composed of three parts of a rear end portion 51, a cylindrical portion 52 and a front end portion 55. The rear end portion 51 has a third lens group L on its inner peripheral surface.
3, and a cam pin 54 is installed on the outer peripheral surface thereof. The cam pin 54 is used for the fourth lens group moving frame 6
The clearance groove 64 of 0 and the cam groove 27 of the cam ring 20 are penetrated, and the tip end thereof is inserted into the guide groove 16 of the fixed barrel 10. Therefore, the third group lens moving frame 50 is prohibited from rotating in the lens barrel by the guide groove 16, and only moves in the optical axis direction. The cylindrical portion 52 is fitted on the outer peripheral surface of the second group lens moving frame 40 on the inner peripheral surface thereof, and has an escape groove 57 for passing the cam pin 42 installed on the second group lens moving frame 40. I have it. Further, the cylindrical portion 52 is provided with a groove portion 53 parallel to the optical axis, and the groove portion 53 has a fourth group lens moving frame 6 to be described later.
The protrusion 62 of 0 is fitted. A cam pin 56 is provided on the outer peripheral surface of the tip portion 55. As described above, the cam pin 56 is fitted into the cam groove 32 of the first lens group moving frame 30, and functions to convert the rotational movement of the first lens group moving frame 30 together with the cam groove 32 into a rectilinear movement in the optical axis direction. Plays.

The fourth group lens moving frame 60 is a frame body which supports the fourth group lens L4 on the inner peripheral surface of the rear end portion.
The fourth group lens moving frame 60 has a cylindrical portion 61 that extends forward from the portion supporting the fourth group lens L4, and has an inner peripheral surface of the cylindrical portion 61 and an outer peripheral surface of the third group lens moving frame 50. It is arranged in the lens barrel so as to be in contact with it. In addition, the cylindrical portion 61 is provided on its inner peripheral surface with a protruding portion 62 which is parallel to the optical axis and has a vertically long shape. As described above, the protrusion 62 is provided in the groove portion 5 provided in the third lens group moving frame 50.
3 is fitted, which allows the fourth lens group moving frame 6
0 is integrated with the third lens group moving frame 50 in the rotation direction about the optical axis. Here, since the third lens group moving frame 50 does not rotate as described above, the fourth lens group moving frame 60 also does not move in the rotation direction. Further, the cam pin 63 is provided on the outer peripheral surface of the rear portion of the cylindrical portion 61.
Is installed, and the tip end of the cam pin 63 is fitted into the cam groove 26 of the cam ring 20. Therefore, the fourth lens group moving frame 60 receives a driving force in the optical axis direction from the cam ring 20 via the cam groove 26 and the cam pin 63.

The focus relay cylinder 70 includes the cam ring 20.
Is a cylindrical member installed on the inner peripheral surface of the medium diameter portion 24,
It is a member that moves relative to both the cam ring 20 and the fixed barrel 10 in the circumferential direction about the optical axis. The focus relay cylinder 70 has a brim portion 73 on the outer peripheral surface of the rear end thereof,
This is engaged with the groove portion 24a of the medium diameter portion 24. Further, the focus relay cylinder 70 has a guide groove 71 parallel to the optical axis.
The cam pin 42 is fitted in the guide groove 71 at its tip. Therefore, the focus relay cylinder 70
When does not rotate, the guide groove 71 functions as a linear guide groove, and limits the movement direction of the second lens group moving frame 40 to the optical axis direction via the cam pin 42. Further, when the focus relay cylinder 70 rotates, the rotational movement is
By the cam pin 42 and the cam groove 28, the movement is converted into a rotational movement in the optical axis direction, and the second lens group moving frame 40 is moved to the cam groove 28.
It moves in the optical axis direction according to the shape of.

The zoom ring 80 is an annular member that is manually rotated when adjusting the focal length, and is rotatably attached to the outer peripheral surface of the large diameter portion 13 of the fixed barrel 10. The zoom ring 80 is provided with a guide groove 81 parallel to the optical axis on its inner peripheral surface. In the guide groove 81, the pin 2
3, the cam ring 20 rotates integrally with the zoom ring 80 when the zoom ring 80 rotates.

The segment gear ring 90 is a gear member for transmitting a driving force for performing automatic focusing from a camera body (not shown), and is rotatably installed on the inner peripheral surface of the large diameter portion 13 of the fixed barrel 10. There is. The segment gear ring 90 is
A segment gear 91 is provided on its inner peripheral surface, and the segment gear 91 meshes with a drive gear (not shown).
Further, the segment gear ring 90 is provided with a protrusion 92 for transmitting a driving force to a key member 110 described later on the outer peripheral surface thereof.

The focus ring 100 is an annular member that is manually rotated when performing a focusing operation. The focus ring 100 is fitted to the tip of the fixed barrel 10 by a bayonet method and can rotate at a predetermined angle. A key member 110, which is a member for transmitting the rotational movement of the focus ring 100 to the focus relay barrel 70, is provided on the inner peripheral surface of the focus ring 100.
Are attached by machine screws 115. The focus ring 100 and the large diameter portion 21 correspond to the outer cylinder portion of the lens barrel in the present invention.

As shown in FIG. 1B, the key member 110.
Is an annular portion 111 having a substantially circular shape that is fixed to the inner peripheral surface of the focus ring 100, and from there, to the rear,
The extension 112 extends parallel to the optical axis. The extension portion 112 is provided with a guide groove 113 that is parallel to the optical axis in the central portion thereof. As shown in FIG. 1 (A), the guide groove 113 is fitted with the tip end portion of a pin 72 installed on the outer peripheral portion of the focus relay cylinder 70. Therefore, when the focus ring 100 is rotated by a manual operation, the rotational movement is transmitted to the focus relay barrel 70 via the key member 110, and the focus relay barrel 70 also rotates. Furthermore, the rotational movement of the focus relay barrel 70 is
It is converted into movement in the optical axis direction of the second lens group moving frame 40 via the cam pin 42 and the cam groove 28, and the focusing operation is performed.
Since the focus relay cylinder 70 moves integrally with the cam ring 20 in the optical axis direction, the guide groove 113 has a length in the optical axis direction equal to a movement amount M of the cam ring 20 in the optical axis direction, which will be described later. It has become a length.

The key member 110 has a groove 114 at its rear end (FIG. 1 (B)).
The projection 92 of the segment gear ring 90 is engaged. As a result, during automatic focusing, the segment gear ring 9
When 0 rotates, the rotation causes the protrusion 92 and the groove 11 to rotate.
4 is transmitted to the key member 110. As a result, the focus relay barrel 70 makes a rotary motion in conjunction with the segment gear ring 90, and the rotary motion is converted into a motion of the second lens group moving frame 40 in the optical axis direction, as described above.
Automatic focusing is performed. At this time, since the focus ring 100 is also interlocked with the key member 110, the operation state of the automatic focusing mechanism can be confirmed from the outside of the lens barrel.

Next, the operation of this embodiment will be described.
FIG. 2 is a view showing a cross-sectional view of the present embodiment, and the lower half of the drawing shows a case where the zoom lens barrel has an optical system arranged for wide-angle image capturing (hereinafter referred to as “wide state”). In addition, the upper half of the figure shows the state when the optical system is arranged for shooting a telephoto image (hereinafter, referred to as “tele state”). 3 and 4 are diagrams for explaining the movement of each lens group in the present embodiment.
Shows a development view of the escape groove 14, the cam groove 32, and the guide groove 81. FIG. 4 shows the guide groove 16, the cam groove 17, the cam groove 26,
The development view of the cam groove 27 and the cam groove 28 is shown. 3 and 4, the left side of the drawing corresponds to the front of the lens barrel, and the alternate long and short dash line F represents a straight line parallel to the optical axis of the lens barrel.

First, the case where focusing is performed in the automatic focusing mode in this embodiment will be described. In the automatic focusing mode, the driving force in the rotational direction is transmitted from the camera body to the segment gear ring 90 shown in FIG. 1 via a known power transmission mechanism (not shown). Next, the driving force is applied from the protrusion 92 to the key member 110, and from the key member 110 via the pin 72 to the focus relay cylinder 70.
The focus relay barrel 70 is rotated.
In the guide groove 71 of the focus relay barrel 70, the cam pin 42
Since the tip end portion of the cam pin 42 is fitted, the cam pin 42 makes a rotary motion in conjunction with the focus relay cylinder 70, and the cam groove 2
Move within 8.

When the lens barrel is in the telescopic state, the cam pin 42 moves up and down on the upper side of the cam groove 28 shown in FIG. The maximum rotation angle of the cam pin 42 at this time is θt, and the amount of movement in the optical axis direction is A. Therefore, the second group lens moving frame 40 also moves within the range of the distance A in the optical axis direction,
Focusing is performed. When the lens barrel of the present embodiment is changed from the telephoto state to the wide state, the cam ring 20 rotates due to an operation described later, so that the cam pin 42 moves to the lower side of the cam groove 28 in the drawing. When the above-described automatic focusing is performed in this state, the cam pin 42 moves in the area of the cam groove 28 indicated by the rotation angle θw equal to the rotation angle θt. As a result, the second group lens moving frame 40 is moved back and forth in the optical axis direction by the length B in the optical axis direction of the area represented by θw, and focusing is performed.

On the other hand, when the focusing operation is performed in the manual focusing mode, the focus ring 100 is manually rotated. The rotational movement of the focus ring 100 is transmitted to the key member 110 via the machine screw 115, and thereafter,
By the same mechanism and operation as in the automatic focusing mode,
Focusing is performed by converting the movement of the second lens group moving frame 40 into the optical axis direction.

Next, the operation of the present embodiment when adjusting the focal length will be described. In order to simplify the description, the focus relay cylinder 70 will be referred to as the cam ring 2 in the following.
It is assumed that the cam pin 42 does not rotate with respect to 0, and the cam pin 42 performs only the operation related to the focal length adjustment.

In the present embodiment, when the lens barrel is set to the wide state, the zoom ring 80 is rotated clockwise as viewed from the rear of the lens barrel, and its rotational movement is guided by the guide groove 81.
And the pin 23 to the cam ring 20 to rotate the cam ring 20 by the same angle. Zoom ring 80
4 is rotated clockwise, the cam pin 29 in FIG.
Is located at the upper end of the cam groove 17 in the figure. As a result, the cam ring 20 is located at the rearmost position with respect to the middle diameter portion 15 of the fixed barrel 10, and the entire cam ring 20 is housed in the outer barrel portion of the lens barrel as shown in the lower side of FIG. It The cam pins 42, 54, 63 are located at the lower ends of the cam grooves 28, 27, 26 shown in FIG. 4, respectively. Therefore, the second lens group moving frame 40 is located at the frontmost position in the range in which the second lens group moving frame 40 can move relative to the cam ring 20, and conversely, the third lens group moving frame 50 and the fourth lens group moving frame 60 are the most movable. It is located rearward (Fig. 2, lower side).

On the other hand, the pin 23 installed at the rear end of the cam ring 20 is located at the upper end of the clearance groove 14 shown in FIG. 3, that is, at the rear end of the zoom ring 80. On the other hand, the cam groove 32 of the first lens group moving frame 30 shown in FIG. 3 is interlocked with the rotational movement of the cam ring 20, and therefore the cam pin 56.
Is located at its lower end. Therefore, the first lens group moving frame 30 is located at the rearmost position within the range in which the first lens group moving frame 30 can move relative to the cam ring 20, and as shown in the lower side of FIG. The whole 31 is housed in the large-diameter portion 21 of the cam ring 20.

When the zoom ring 80 is rotated counterclockwise from the above state, the lens barrel of this embodiment shifts to the tele state. When the zoom ring 80 is fully turned counterclockwise, the cam pin 29 moves to the lower end of the cam groove 17 shown in FIG. 4 in the figure. As a result, the cam ring 20 is extended forward by the distance M with respect to the middle diameter portion 15 of the fixed barrel 10, and as shown in the upper side of FIG. The diameter portion 21 is projected forward. Similarly, the pin 23 moves to the lower end of the escape groove 14 (FIG. 3),
Like the cam ring 20, it moves forward by a distance M and comes to be located at the front end of the zoom ring 80 (FIG. 2).
Since the distance M is set shorter than the length of the large diameter portion 21 in the optical axis direction, the rear end of the large diameter portion 21 is
It is always located rearward of the tip of the outer cylinder of the lens barrel.

The cam pins 42, 54 and 63 move to the upper ends of the cam grooves 28, 27 and 26 shown in FIG. 4, respectively. At this time, the second lens group moving frame 40 moves backward by a distance m2 with respect to the cam ring 20, and the third lens group moving frame 50 and the fourth lens group moving frame 60 move forward by m3 and m4, respectively. Moving. Therefore, the distance that each lens moving frame 40, 50, 60 moves with respect to the fixed barrel 10 is M-m2, M + m3, M + m4, respectively.

On the other hand, the cam pin 56 moves to the upper end of the cam groove 32, whereby the first lens group moving frame 30 is extended forward from the second lens group moving frame 40 by a distance m1. In other words, the first lens group moving frame 30 is moved forward by a distance (m1 + m3) from the cam ring 20 and by (M + m1 + m3) from the fixed barrel 10. As a result, as shown in the upper side of FIG. 2, the entire first lens group moving frame 30 is located in front of the outer tube portion of the lens barrel. In addition, the engagement position between the first group lens moving frame 30 and the cam ring 20 by these series of operations,
That is, the position where the pin 33 and the guide groove 22 are engaged moves from the rear end of the guide groove 22 to the front end.

As described above, in the lens barrel of this embodiment, the large diameter portion 2 of the cam ring 20 in the wide state.
1 is entirely housed in the outer cylinder part of the lens barrel, and the entire cylindrical part 31 of the first lens group moving frame 30 is housed in the large diameter part 21 of the cam ring 20. Therefore, the lens barrel of the present embodiment has a short overall length in the optical axis direction and a compact shape when the lens group is pulled behind the lens barrel.

On the other hand, in this embodiment, the cam ring 20 is extended from the fixed barrel 10, the third lens group moving frame 50 is extended from the cam ring 20, and the first lens group moving frame 30 is further extended from the third lens group moving frame 50. The moving range of the first lens group moving frame 30 is widened by adopting the extension structure. As a result, the lens barrel of the present embodiment can change the focal length in a wide range while having the compact shape as described above.

Also, in this embodiment, the cam ring 20 is used.
The large diameter portion 21 of is always engaged with the outer peripheral surface of the cylindrical portion 31 of the first group lens moving frame 30 at the inner peripheral surface thereof. Therefore, even when the rear end of the first group lens moving frame 30 is located in front of the front end of the outer barrel of the lens barrel and an opening is formed therebetween, the large-diameter portion 21 covers the opening. It functions as a member and prevents the mechanism inside the lens barrel from being visible from the outside. Therefore, the lens barrel of this embodiment is
When the first lens group moving frame 30 is extended forward, it does not spoil the appearance. Moreover, in the present embodiment, since the large diameter portion 21 is one part of the cam ring 20, it is not necessary to significantly increase the number of parts to add the blocking member, and the above effect can be provided at low cost. Is.

[0038]

As described above in detail, according to the present invention, the lens moving frame is extended such that the rear end of the lens moving frame is located in front of the front end of the outer cylinder portion, and the lens moving frame and the outer cylinder are arranged. Even if an opening is formed between the cam ring and the section, the cam ring drive mechanism drives the cam ring in the optical axis direction so that the opening is covered by the outer diameter section of the cam ring.
At this time, the large-diameter portion of the cam ring functions as a shielding member and prevents the internal mechanism of the lens barrel from being viewed from the outside through the opening. Therefore, the lens barrel of the present invention has an effect of not impairing the appearance even when the lens moving frame is sent forward from the outer tubular portion in order to widen the range of the adjustable focal length. Further, in the present invention, since the member that shields the opening is the large diameter portion of the cam ring, the above effect is realized with a small number of parts, and the lens barrel according to the present invention can be provided at low cost. I have to.

Further, the lens moving frame has a straight groove parallel to the optical axis provided on one of the inner peripheral surface of the large diameter portion of the cam ring or the outer peripheral surface of the lens moving frame and the straight groove provided on the other side. Since it is configured to be linearly guided with respect to the cam ring by the projection part that fits in the lens barrel of the present invention, the lens moving frame and the cam ring are stably moved relative to each other only in the optical axis direction. effective. Furthermore, the lens moving frame has a cylindrical portion that is housed in or extended from the large diameter portion of the cam ring, and the length of the cylindrical portion and the large diameter portion of the cam ring in the optical axis direction is determined by the lens moving frame driving mechanism. Since the frame is configured to have a length equal to the relative movement with respect to the cam ring, the present invention is short in the optical axis direction and has a compact shape when the lens movement frame is housed in the outer tube portion of the lens barrel. Produce an effect.

[Brief description of drawings]

FIG. 1 is a sectional view of a lens barrel according to the present invention and a partial side view of a key member used in the lens barrel.

FIG. 2 is a sectional view when the lens barrel according to the present invention is in a wide state and a sectional view when it is in a tele state.

FIG. 3 is a development view of a cam groove provided in the lens barrel according to the present invention.

FIG. 4 is a development view of a cam groove provided in the lens barrel according to the present invention, which is different from FIG.

[Explanation of symbols]

10 Fixed Cylinder 11 Rear Part 12 Mount Part 13 Large Diameter Part 14 Escape Groove 15 Medium Diameter Part 16 Guide Groove 20 Cam Ring 21 Large Diameter Part 22 Guide Groove 23 Pin 24 Medium Diameter Part 24a Groove 25 Small Diameter Part 26 Cam Groove 27 Cam Groove 28 Cam Groove 29 Cam pin 30 First group lens moving frame 31 Cylindrical part 32 Cam groove 33 Pin 40 Second group lens moving frame 42 Cam pin 50 Third group lens moving frame 51 Rear end part 52 Cylindrical part 53 Groove part 54 Cam pin 55 Tip part 56 Cam pin 57 Escape Groove 60 Fourth Group Lens Moving Frame 61 Cylindrical Part 62 Projection 63 Cam Pin 64 Escape Groove 65 Escape Groove 70 Focus Relay Tube 71 Guide Groove 72 Pin 73 Flange 80 Zoom Ring 81 Guide Groove 90 Segment Gear Ring 91 Segment Gear 92 Projection 100 Focus ring 110 Key member 111 Annular portion 11 Extension portion 113 Guide groove 114 Groove portion 115 Machine screw L1 First group lens L2 Second group lens L3 Third group lens L4 Fourth group lens A Optical axis direction movement of second group lens moving frame by focusing operation in tele state Distance B Moving distance in the optical axis direction of the second lens group moving frame due to focusing operation in the wide state F Straight line M parallel to the optical axis of the lens barrel M Moving distance in the optical axis direction of the cam ring by adjusting the focal length m1 By adjusting the focal length Optical axis moving distance m2 of first lens group moving frame Optical axis moving distance m3 of second lens group moving frame by focal length adjustment Optical axis moving distance m4 of third lens group moving frame by focal length adjustment m4 Focal length adjustment Distance of the fourth lens group moving frame in the optical axis direction

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Claims (3)

(57) [Claims] 1. An outer cylinder part, a large diameter part arranged inside the outer cylinder part, and a small diameter part located inside the large diameter part, and a circumferential direction about the optical axis and A cam ring movable in the optical axis direction, a lens moving frame that supports a part of the optical system, and is engaged with a large diameter portion inner peripheral surface of the cam ring at a rear portion of the outer peripheral surface so as to be relatively movable in the optical axis direction, A cam ring drive mechanism that drives the cam ring in the optical axis direction; and a lens movement frame drive mechanism that moves the lens movement frame relative to the cam ring in conjunction with the cam ring, and moves the lens movement frame. by a lens barrel for changing the focal length, the lens moving frame drive mechanism, a rear end of the lens moving frame feeding said lens moving frame to be positioned in front of the front end of the outer cylindrical portion, the Lens moving frame drive The mechanism is such that the front end of the large diameter portion of the cam ring is always positioned in front of the rear end of the lens moving frame, and the cam ring drive mechanism is such that the rear end of the large diameter portion of the cam ring is the front end of the outer tubular portion. and decremental the cam ring so as to be located more rearward, and always the lens moving frame
A lens barrel, wherein an opening formed between the outer barrel and the outer barrel is shielded . 2. The lens barrel according to claim 1 , wherein the lens moving frame is an optical axis provided on one of an inner peripheral surface of a large diameter portion of the cam ring or an outer peripheral surface of the lens moving frame. A lens barrel, which is guided linearly with respect to the cam ring by a straight groove that is parallel to the above and a projection portion that is provided on the other side and that fits into the straight groove. 3. The lens barrel according to claim 1 , wherein the lens moving frame is housed in a large diameter portion of the cam ring,
Alternatively, the length of the cylindrical portion and the large diameter portion of the cam ring in the optical axis direction is a length with which the lens moving frame drive mechanism moves the lens moving frame relative to the cam ring. A lens barrel characterized by being equal to.