JP2003270513A - Lens barrel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens barrel which is improved in the moving accuracy of lenses by providing the lens barrel with energizing means for energizing a second tubular body in such a manner that a cam follower touches a cam surface of a positioning cam when the cam follower engages the positioning cam. <P>SOLUTION: The lens barrel 1 formed in such a manner that an intermediate tube 7 can be drawn out of and into a stationary tube 6 is provided with a biasing ring 25 for biasing the intermediate tube 7 in a draw out direction and a direction opposite to the draw out direction by touching the intermediate tube 7 when the intermediate tube 7 is drawn out to a photographable position. As a result, the biasing force does not act on the intermediate tube 7 before the intermediate tube 7 is drawn out to the photographable position and therefore the drawing out of the intermediate tube 7 is made smooth and the moving accuracy of the lens is improved. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens barrel used for a camera or the like.

[0002]

2. Description of the Related Art Conventionally, as a lens barrel used in a camera or the like, as disclosed in Japanese Patent Laid-Open No. 2000-111781, a fixed barrel, a rear barrel and a front barrel are provided, and a rear barrel is provided for the fixed barrel. The front barrel can be moved back and forth in the optical axis direction with respect to the rear barrel, the first group lens holding frame is attached to the front barrel, and the second group lens holding frame and the third group are attached to the rear barrel. It is known that each lens holding frame is attached via a cam groove. This lens barrel includes a front barrel and a second barrel.
A pulling spring is provided between the group lens holding frame and the second group lens holding frame is pulled forward by this pulling spring to eliminate mechanical rattling of the second group lens holding frame.
It is intended to accurately move the second lens group in the optical axis direction.

[0003]

However, in such a lens barrel, if the distance between the front barrel and the second group lens holding frame changes due to the front barrel extending from the rear barrel, The pulling force of the tension spring fluctuates. Therefore, the second group lens holding frame cannot be stably pulled. Further, fluctuations in the pulling force of the pulling springs cause fluctuations in the load of the motor that is the drive source for the movement of the front cylinder or the rear cylinder, which causes variations in the lens stop accuracy during zooming.

Therefore, the present invention has been made in order to solve such a problem, and provides a lens barrel which ensures the movement of the lens and improves the positioning accuracy during use. With the goal.

[0005]

In order to achieve such an object, a lens barrel according to the present invention comprises a first cylinder and a second cylinder which accommodate a lens optical system and are arranged in multiplex inside and outside. And a third cylinder that engages with the second cylinder and rotates the second cylinder, and a movement cam is formed on one of the first cylinder and the second cylinder and a movement cam is formed on the other side. A cam follower that engages with is formed, and by rotating the second cylinder together with the third cylinder, the second cylinder is extended from the collapsed position to the used position with respect to the first cylinder through the cam action of the moving cam and the cam follower. Also, in the retractable lens barrel, it is connected to the moving cam, engages with the cam follower when the second cylinder is extended to the use position, and only allows rotation of the second cylinder through the cam follower when engaged. Positioning cam and positioning When the cam follower is engaged with the arm, characterized in that a biasing means for biasing the second tubular body so as to abut against the cam surface of the positioning cam of the cam follower.

Further, in the lens barrel according to the present invention, the above-mentioned urging means includes an engaging portion which engages with the third cylinder and at least one spring portion which abuts against the second cylinder and urges it. It is characterized by being formed integrally.

Further, the lens barrel according to the present invention is characterized in that the urging means is formed in a ring shape by disposing the engaging portion and the spring portion at equal intervals in the circumferential direction.

Further, the lens barrel according to the present invention is suitable when applied to a lens barrel that houses a taking lens system of a camera.

According to these aspects of the invention, when the cam follower is engaged with the positioning cam, the second cylinder is urged so that the cam follower contacts the cam surface of the positioning cam. Since the urging means is not urged until is moved to the predetermined position, the load of the drive source for moving the second cylinder is reduced, and the load fluctuation does not occur. For this reason, it is possible to reliably perform the extension of the second cylindrical body and the lens movement associated therewith with a smaller driving force. Also,
When the second cylindrical body is extended to a predetermined position, the second cylindrical body is biased to prevent the positioning accuracy of the second cylindrical body from being lowered due to backlash.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. In the drawings, the same elements are designated by the same reference numerals and the description thereof will be omitted. Further, the dimensional ratios in the drawings do not always match those described.

FIG. 1 shows an explanatory view of the lens barrel according to this embodiment. As shown in the figure, the lens barrel 1 according to the present embodiment is used for a photographing optical system of a camera 2. The lens barrel 1 contains a first lens group 3, a second lens group 4 and a third lens 5. The first lens group 3, the second lens group 4, and the third lens 5 are lens optical systems sequentially arranged along the optical axis O, and constitute a photographing optical system of the camera 2.

The lens barrel 1 has a fixed frame 6 fixed to the main body of the camera 2, an intermediate barrel 7 that can be extended and retracted with respect to the fixed frame 6, and a movable extension and extension with respect to the intermediate barrel 7. And a tube 8. The fixed frame 6, the intermediate cylinder 7 and the movable cylinder 8 are arranged in multiplex inside and outside with the optical axis O as the center.

The fixed frame 6 is a cylindrical member having an opening 10 at one end and an opening at the other end. An image plane 11 of the photographing optical system is formed in the opening 10. The opening 10 is used as a mounting space for mounting the holding frame 13 of the CCD 12, which is an image sensor. The holding frame 13 is the CCD 1
It is a frame body for holding 2 and is configured separately from the fixed frame 6 and attached to the opening 10 of the fixed frame 6. The image plane 11 may be set inside the fixed frame 6 with respect to the opening 10.

The holding frame 13 is attached to the opening 10 by being held by the edge of the opening 10 and being pressed by the holding plate 14. As a result, the CCD held by the holding frame 13
12 is arranged on the image plane 11.

A cam groove 9 is formed on the peripheral surface of the fixed frame 6. The cam groove 9 is formed so as to penetrate the inside and outside of the peripheral surface of the fixed frame 6, and is formed in a spiral shape, for example. The cam follower 23 of the intermediate cylinder 7 is inserted into and engaged with the cam groove 9. The cam follower 23 is provided so as to project outward from the outer peripheral surface of the intermediate cylinder 7.

A pin 24 is provided at the tip of the cam follower 23.
Is attached. The pin 24 is a member for transmitting the rotational force to the intermediate cylinder 7, and is inserted into the vertical groove 16 a formed in the rotary cylinder 16. The pin 24 functions as a protrusion provided on the peripheral surface of the intermediate cylinder 7. Rotating cylinder 16
Is a cylindrical member disposed outside the fixed frame 6, and rotates with the driving of a driving source such as a motor. The vertical groove 16a is
The inner surface of the rotary cylinder 16 is formed to be concave, and extends in the direction along the optical axis O of the photographing optical system, that is, in the optical axis direction.

As the rotary cylinder 16 rotates, the pin 2
4 and the cam follower 23 move in the circumferential direction and along the cam groove 9 in the optical axis direction. As a result, the intermediate cylinder 7 moves in the optical axis direction while rotating, and is extended or retracted with respect to the fixed frame 6.

A biasing ring 25 is attached to the rotary cylinder 16. The urging ring 25 presses the cam follower 23 against the side wall surface (cam surface) of the cam groove 9 to contact the intermediate cylinder 7 when the intermediate cylinder 7 is extended and reaches the photographing position (use position) from the retracted position. It functions as a biasing means for biasing 7.

The term "photographable position" as used herein refers to a position where proper photographing can be performed by the second lens group 4, the third lens 5 and the like. The urging ring 25 is a ring-shaped member having substantially the same diameter as that of the rotary cylinder 16, is attached to the end of the rotary cylinder 16, and forms a leaf spring portion 25a that urges the pin 24.

A vertical groove 17 extending in the optical axis direction is formed on the inner peripheral surface of the fixed frame 6. The vertical groove 17 is a groove for stopping the rotation of the straight advance key ring 18 and guiding the straight advance key ring 18 in the optical axis direction. The straight-movement key ring 18 is an annular member having substantially the same diameter as the intermediate cylinder 7, and is rotatably attached to the intermediate cylinder 7 at the rear end of the intermediate cylinder 7. Therefore, the straight-ahead key ring 18 moves in the optical axis direction together with the intermediate cylinder 7 while allowing the intermediate cylinder 7 to rotate.

The straight key ring 18 has a support portion 18a extending forward. The support portion 18a is hooked on the rear end of the movable barrel 8 to prevent the movable barrel 8 from rotating. A pin 21 protruding from the outer peripheral surface is provided at the rear end of the movable barrel 8. The pin 21 is inserted into a cam groove 22 formed on the inner peripheral surface of the intermediate cylinder 7. The cam groove 22 is formed in a spiral shape along the inner peripheral surface of the intermediate cylinder 7, for example.

Even if the intermediate cylinder 7 rotates, the movable cylinder 8 does not rotate because it is supported by the straight advance key ring 18. However, the pin 21 moves in the optical axis direction according to the shape of the cam groove 22. As a result, the movable barrel 8 moves in the optical axis direction as the intermediate barrel 7 rotates, and is extended or retracted with respect to the intermediate barrel 7.

The first lens group 3 is fixed to the movable barrel 8 via a first lens holding frame 30 and the like. The first lens group 3 moves in the optical axis direction as the movable barrel 8 is extended and retracted. A second lens holding frame 40 that holds the second lens group 4 is fixed to the intermediate cylinder 7. Therefore, the second lens group 4 moves in the optical axis direction in accordance with the extension and retraction of the intermediate cylinder 7.

A focus motor 41 is attached to the second lens holding frame 40 by screwing or the like.
The focus motor 41 is a drive unit for moving the third lens 5 which is the focus lens of the photographing optical system in the optical axis direction, and is a range finder (not shown) installed in the camera 2 for measuring the distance to the subject. Drive based on the output signal of.

The rotary shaft 42 of the focus motor 41 has a thread groove formed on its peripheral surface and functions as a lead screw. A third lens holding frame 43 is screwed onto the rotating shaft 42. A shaft 44 installed in the second lens holding frame 40 penetrates the third lens holding frame 43. The shaft 44 functions as a guide shaft of the third lens holding frame 43 and a rotation preventing unit. When the rotation shaft 42 of the focus motor 41 rotates, the third lens holding frame 43 and the third lens 5 move in the optical axis direction along with the rotation.

FIG. 2 is a perspective view of the biasing ring and the rotary cylinder.

As shown in the figure, the urging ring 25 is a ring-shaped member and is attached to the end of the rotary cylinder 16. An engaging portion 25b is formed on the biasing ring 25 by being bent in the optical axis direction. The biasing ring 25 is attached to the rotary cylinder 16 by engaging the engagement portion 25b with the protrusion 16b formed on the outer periphery of the rotary cylinder 16. Therefore, when the rotary cylinder 16 rotates, the urging ring 2
5 also rotates together.

The leaf spring portion 25a of the urging ring 25 is arranged at an extended position of the vertical groove 16a, and is formed by bending in a convex shape toward the vertical groove 16a. Therefore, the leaf spring portion 25a
Urges the pin 24 moving along the vertical groove 16a to the opposite side in the moving direction. The engagement portion 25b and the leaf spring portion 25a are arranged at substantially equal intervals in the circumferential direction.

FIG. 3 is a development view in which the intermediate cylinder 7 is developed in a plane shape. FIG. 4 is a development view in which the fixed cylinder 6 is developed in a plane.

As shown in FIG. 3, at the end of the intermediate cylinder 7,
A plurality of cam followers 23 are formed, and for example, three cam followers 23 are arranged at equal intervals in the circumferential direction. The cam follower 23 is configured as a protrusion having a circular cross section.

As shown in FIG. 4, the cam groove 9 of the fixed barrel 6
Are formed corresponding to the cam followers 23, for example, three are formed at equal intervals in the circumferential direction of the fixed cylinder 6. The cam followers 23 are inserted into the respective cam grooves 9, and the cam followers 23 are moved along the forming direction thereof. Cam groove 9
Has a moving cam 9a formed to be inclined with respect to the optical axis direction (direction of the optical axis O) and a positioning cam 9b formed to be perpendicular to the optical axis direction. Positioning cam 9
b is connected to the moving cam 9a, engages with the cam follower 23 when the intermediate cylinder 7 is extended to the use position, and permits rotation of the intermediate cylinder 7 through the cam follower 23 at the time of engagement.

The cam follower 23 moves the moving cam 9a by the rotation of the intermediate cylinder 7. At that time, cam follower 2
Since 3 moves in the optical axis direction, the intermediate cylinder 7 is extended or retracted. On the other hand, cam follower 2
When 3 is in the positioning cam 9b, even if the intermediate cylinder 7 rotates, it does not move in the optical axis direction, and therefore the intermediate cylinder 7 is not extended or retracted. In this case, the rotation of the intermediate cylinder 7 causes the movable cylinder 8 to be extended or retracted with respect to the intermediate cylinder 7, thereby performing predetermined zooming. Also,
When the cam follower 23 is on the positioning cam 9b, the camera 1 is ready for shooting, and the pin 24 is biased by the biasing ring 25 (see FIG. 1).

Next, the operation of the lens barrel according to this embodiment will be described.

As shown in FIG. 5, when the rotary cylinder 16 is rotated by driving a drive source (not shown) such as a motor in a collapsed state in which the intermediate cylinder 7 and the movable cylinder 8 are accommodated in the fixed cylinder 6, the rotation cylinder 16 is rotated accordingly. The pin 24 and the cam follower 23 rotate and move, and the intermediate cylinder 7 rotates and extends. Further, as the intermediate cylinder 7 rotates, the pin 21 moves in the optical axis direction according to the shape of the cam groove 22, so that the movable cylinder 8 is extended from the intermediate cylinder 7.

At this time, the pin 24 of the intermediate barrel 7 is not biased by the biasing ring 25 until the intermediate barrel 7 is extended to a position where the lens barrel 1 is ready for photographing. For this reason,
Due to the urging force of the intermediate cylinder 7 for removing the backlash, the load or the load of the motor or the like serving as the feeding drive source does not increase or change. Therefore, the intermediate cylinder 7 can be reliably delivered with a small driving force.

When the intermediate cylinder 7 is extended and the cam follower 23 reaches the positioning cam 9b (see FIG. 4) and the lens barrel 1 is ready for photographing, as shown in FIG. 6, the pin of the intermediate cylinder 7 is pinched. 24 is the leaf spring portion 2 of the urging ring 25
5a is contacted and moves against the biasing force of the leaf spring portion 25a. Therefore, the intermediate cylinder 7 is biased in the optical axis direction via the pin 24. As a result, even if there is play between the cam follower 23 and the cam groove 9, the intermediate cylinder 7 is biased in the urging direction of the urging ring 25 and removed. Therefore, the lens of the photographing optical system can be moved accurately, and proper zooming can be performed.

As described above, according to the lens barrel 1 of the present embodiment, since the urging ring 25 is not urged until the intermediate barrel 7 is extended to the photographing position, the intermediate barrel 7 is not urged.
The load on the drive source for feeding the power is reduced, and the load does not fluctuate. Therefore, the extension of the intermediate cylinder 7 and the accompanying lens movement can be reliably performed with a smaller driving force. Further, when the intermediate cylinder 7 is extended to the image-capturing position, the intermediate cylinder 7 is urged by the urging ring 25 to prevent the positioning accuracy of the intermediate cylinder 7 from being lowered due to backlash.

In the present embodiment, the case where the intermediate cylinder 7 is biased to perform the biasing has been described, but the lens barrel according to the present invention is not limited to such a case.
It may be applied when biasing a cylinder body other than the intermediate cylinder 7 by biasing it.

Further, in the present embodiment, the case where the present invention is applied to the lens barrel for feeding out the two barrels (moving barrel 8 and intermediate barrel 7) has been described. However, the lens barrel according to the present invention has such a structure. The present invention is not limited to this, and may be applied to a lens barrel that extends one or three or more cylinders.

Further, although the case where the lens barrel according to the present invention is applied to a digital camera has been described in the present embodiment, the lens barrel according to the present invention is not limited to such a one, and the digital camera is not limited to such a lens barrel. It may be applied to optical devices other than the above.

[0041]

As described above, according to the present invention, when the cam follower is engaged with the positioning cam, the second cylinder is urged so that the cam follower contacts the cam surface of the positioning cam. Since the urging means is not urged until the second cylindrical body is extended to the predetermined position, the load of the drive source that extends the second cylindrical body is reduced, and the load fluctuation does not occur. For this reason, it is possible to reliably perform the extension of the second cylindrical body and the lens movement associated therewith with a smaller driving force. Further, when the second cylindrical body is extended to a predetermined position, the second cylindrical body is biased to prevent the positioning accuracy of the second cylindrical body from being lowered due to backlash.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a lens barrel according to an embodiment of the present invention.

FIG. 2 is an explanatory view of a biasing ring and a rotary cylinder in the lens barrel of FIG.

FIG. 3 is an explanatory diagram of an intermediate barrel in the lens barrel of FIG.

FIG. 4 is an explanatory diagram of a fixed barrel in the lens barrel of FIG.

5 is an explanatory view of a retracted state of the lens barrel of FIG.

FIG. 6 is an explanatory diagram of an operation of the lens barrel of FIG.

[Explanation of symbols]

1 ... Lens barrel, 2 ... Camera, 3 ... First lens group, 4 ...
Second lens group, 5 ... Third lens, 6 ... Fixed frame (first cylinder), 7 ... Intermediate cylinder (second cylinder), 8 ... Moving cylinder, 9 ... Cam groove, 9a ... Moving cam, 9b … Positioning cam, 16…
Rotating cylinder (third cylinder), 23 ... Cam follower, 25 ... Energizing ring, 25a ... Leaf spring, O ... Optical axis.

Claims (3)

[Claims] 1. A third cylinder that has a first cylinder and a second cylinder that accommodates a lens optical system and is multiply arranged inside and outside, and that engages with the second cylinder and rotates the second cylinder. A moving cam is formed on one of the first cylindrical body and the second cylindrical body, and a cam follower that engages with the moving cam is formed on the other side of the first cylindrical body and the second cylindrical body. A lens barrel in which the second barrel can be extended and retracted from the retracted position to the use position with respect to the first barrel through the cam action of the moving cam and the cam follower by rotating the barrel. A positioning cam that is connected to the use cam and that engages with the cam follower when the second tubular body is extended to the use position, and allows only rotation of the second tubular body through the cam follower at the time of engagement; For positioning And a biasing means for biasing the second cylinder so that the cam follower contacts the cam surface of the positioning cam when the cam follower is engaged with the lens mirror. Torso 2. The biasing means is integrally formed with an engaging portion that engages with the third tubular body and at least one spring portion that abuts and biases the second tubular body. The lens barrel according to claim 1, wherein: 3. The lens mirror according to claim 2, wherein the urging means is formed in a ring shape by arranging the engaging portion and the spring portion at substantially equal intervals in the circumferential direction. Torso