JPH0980287A - Lens barrel - Google Patents

Abstract

(57) Abstract: The rattling of the cam mechanism that has conventionally occurred when the lens group holding cylinder is driven by a part of the cam mechanism that rotates in the optical axis direction while rotating around the optical axis. Provide a lens barrel that can be removed. SOLUTION: A cam mechanism (cam pin 18 and cam ring 6) for moving the second lens group holding barrel 12 in the optical axis direction while rotating the second lens group holding barrel 8 and the second lens group holding barrel. The coil spring 13 is provided between the annular plate 9 and the second lens group holding barrel 12 to apply a force in the optical axis direction to the coil 12 to remove the rattling of the cam mechanism, the annular plate 9 that receives the coil spring 13. And a ball 11.

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, and more particularly to a zoom lens barrel.

[0002]

2. Description of the Related Art Conventionally, a cam mechanism for moving a lens group holding barrel inside a housing barrel, and an elastic member for removing a rattling of the cam mechanism by applying a force in the optical axis direction to the lens group holding barrel. A lens barrel including (for example, a coil spring) is known.

In the lens barrel, the slight movement of the lens group holding barrel has a great influence on the optical system. Therefore, if the operation error of the cam mechanism is reduced as described above, more accurate photographing can be performed. Like The cam mechanism generally includes a cam pin provided in the lens group holding barrel, a cam barrel for driving the cam pin, and a guide groove for guiding the cam pin driven by the cam barrel in the optical axis direction. Thus, for example, the above-mentioned cam cylinder is adapted to rotate during the zooming operation. In detail, the above-mentioned cam pin is inserted into a cam groove formed in the cam barrel, and its tip end is fitted into the above-mentioned guide groove.

When the cam barrel rotates during the zooming operation, the cam pin drives the cam barrel, and the lens group holding barrel moves together with the cam pin in the optical axis direction.
At this time, since a force in the optical axis direction due to the coil spring is applied to the lens group holding cylinder, the cam pin provided on the lens group holding cylinder is always pressed against the side wall of the cam groove. To move. In this way, if the cam pin can be moved in the cam groove without backlash, the movement locus of the lens group holding cylinder can always be made constant.

[0005]

Recently, an inner focus type zoom lens barrel has been proposed. The inner focus type zoom lens barrel has a plurality of lens group holding barrels that move straight in the direction of the optical axis during zooming, and one of the multiple lens group holding barrels described above moves around the optical axis during focusing. It is configured to move in the optical axis direction while rotating.

However, in the conventional inner focus type zoom lens barrel, since the one lens group holding barrel makes a rotational movement during the focusing operation, the lens group holding barrel is simply made of a coil spring as described above. It was not possible to press it, and the cam mechanism was not removed.

In view of these problems, the object of the present invention has heretofore been encountered when the lens group holding barrel is driven by a part of a cam mechanism that moves in the optical axis direction while rotating around the optical axis. Another object of the present invention is to provide a lens barrel in which the rattling of the above-mentioned cam mechanism is removed.

[0008]

According to one aspect of the present invention for achieving the above object, a cam mechanism for moving a lens group holding cylinder in the optical axis direction while rotating the lens group holding cylinder, and the lens. An elastic member that removes rattling of the cam mechanism by applying a force in the optical axis direction to the group holding cylinder, and a frictional resistance that occurs when the elastic member directly receives the elastic member and directly contacts the lens group holding cylinder. And a low friction contact mechanism that comes into contact with the lens group holding cylinder with a lower frictional resistance.

[0009]

DETAILED DESCRIPTION OF THE INVENTION A zoom lens barrel as an embodiment of the present invention will be described below with reference to FIG.

The fixed barrel 1 is provided with a mount portion 1a. The fixed cylinder 1 is mounted on a camera body (not shown) via a mount 1a. Outer cylinder part 1b of fixed cylinder 1
An aperture ring 2, a zooming operation ring (zoom ring) 3, and a focusing operation ring (focus ring) 4 are fitted around the outer circumference of the lens so as to be rotatable by a predetermined angle.

A cam barrel (cam ring) 6 having a shape as shown in the figure is slidably fitted to the fixed barrel 1. The cam ring 6 has an inner cylinder portion 6d, an outer cylinder portion 6f, a shape folded back to the outside of the inner cylinder portion 6d, and is an intermediate cylinder located between the inner cylinder portion 6d and the outer cylinder portion 6f. And a part 6e. An interlocking ring 5 is fitted between the intermediate tubular portion 6e and the inner tubular portion 1c of the fixed barrel 1. An interlocking pin 20 is implanted in the interlocking ring 5. The center portion of the interlocking pin 20 passes through the intermediate cylinder portion 6e and the outer cylinder portion 6f of the cam ring 6, respectively. Specifically, in order to allow the central portion of the interlocking pin 20 to move only in the rotational direction with respect to the cam ring 6, escape grooves are formed in the intermediate tubular portion 6e and the outer tubular portion 6f, respectively. The central portion of the interlocking pin 20 is arranged in the clearance groove. The tip of the interlocking pin 20 is engaged with a key member 21 fixed to the inner periphery of the focus ring 4. The key member 21 is a guide member for guiding the tip end portion of the interlocking pin 20 in the optical axis direction.

A cam ring 6 is provided on the inner cylinder portion 1c of the fixed cylinder 1.
A cam groove 1d is formed for moving the optical disc in the optical axis direction while rotating the optical disc around the optical axis. In the cam groove 1d, a cam pin 15 which is planted in the inner cylinder portion 6d of the cam ring 6 is slidably fitted. In the present zoom lens barrel, the cam ring 6 is moved in the optical axis direction while being rotated about the optical axis, so that zooming correction is performed for each lens group described later.

The zoom ring 3 is provided with a guide groove 3a parallel to the optical axis. The cam ring 6 is provided in the guide groove 3a.
The distal end portion of the interlocking pin 14 planted in the outer cylindrical portion 6f is slidably fitted. The central portion of the interlocking pin 14 is inserted with a clearance in a clearance groove 1g formed in the outer cylinder portion 1b of the fixed cylinder 1.

The first lens group G1 is held by the first lens group holding barrel 10. The sliding portion 10a of the first lens group holding barrel 10 includes an outer tubular portion 6f of the cam ring 6 and an intermediate tubular portion 6e.
It is located between and. A cam pin 17 is planted in the sliding portion 10a. The cam pin 17 is the cam ring 6
It is slidably fitted in a guide groove 6a formed in the outer cylindrical portion 6f parallel to the optical axis.

A cam groove 10b for moving the first lens group holding barrel 10 in the optical axis direction while rotating the first lens group holding barrel 10 is formed in the sliding portion 10a. Cam groove 10
The cam pin 1 which is planted in the third lens group holding cylinder 8 is shown in b.
6 are slidably fitted. Third lens group G3
Are held by the third lens group holding cylinder 8.

A second lens group holding cylinder 12 is slidably fitted to the inner circumference of the third lens group holding cylinder 8 and is provided in the third lens group holding cylinder 8.
The lens group holding barrel 8 functions as a housing barrel that houses the second lens group holding barrel 12. The second lens group G2 is held by the second lens group holding cylinder 12. An annular groove 12a is formed around the optical axis on the end surface of the second lens group holding cylinder 12, and an annular plate 9 is arranged therein. The end face of the annular plate 9 and the annular groove 12a of the second lens group holding cylinder 12
V-grooves are formed around the optical axis on each of the bottom surfaces of the. A plurality of rolling members (for example, balls made of plastic or metal) 11 are rotatably held in these V grooves. An elastic member (here, a coil spring) 13 is arranged between the annular plate 9 and the third lens group holding cylinder 8. One end of the coil spring 13 is received by the annular plate 9, and the other end is attached to the cylindrical portion formed on the third lens group holding cylinder 8. The coil spring 13 increases the distance between the annular plate 9 and the third lens group holding barrel 8; that is, applies a force to the annular plate 9 toward the second lens group holding barrel 12 side. The holding cylinder of is urged. Then, in the present embodiment, as a low friction contact mechanism for contacting the second lens group holding cylinder 12 with a frictional resistance lower than the frictional resistance generated when the coil spring 13 directly contacts the second lens group holding cylinder 12, Since the ball 11 and the annular plate 9 are provided, when the second lens group holding cylinder 12 moves in the optical axis direction while rotating, the annular plate 9 does not rotate around the optical axis and the second lens group is not rotated. It moves in the optical axis direction together with the holding tube 12. That is, the second lens group holding barrel 12 can be moved without twisting the coil spring 13.

If the rotational movement of the second lens group holding barrel 12 is promoted in this way, the driving force for driving the second lens group holding barrel 12 by a motor (so-called AF drive (autofocus drive)) Is less.

A fourth lens group holding cylinder 7 is slidably fitted to the inner circumference of the inner cylinder portion 6d of the cam ring 6. The fourth lens group G4 is held by a fourth lens group holding cylinder 7. The above-mentioned third lens group holding tube 8 is slidably fitted on the inner periphery of the fourth lens group holding tube 7. On the outer periphery of the third lens group holding cylinder 8, a convex portion 8c extending parallel to the optical axis is provided. A guide groove 7c parallel to the optical axis is formed on the inner circumference of the fourth lens group holding cylinder 7, and the convex portion 8c is
The guide groove 7c is slidably engaged. The fourth
A cam pin 22 is embedded in the lens group holding cylinder 7. The cam pin 22 is slidably fitted in a cam groove 6g formed in the cam ring 6.

The third lens group holding barrel 8 includes a cam pin 19
Has been planted. The tip of the cam pin 19 is fixed to the fixed cylinder 1
Is slidably fitted in a guide groove 1f formed in the inner cylindrical portion 1c and parallel to the optical axis. The center portion of the cam pin 19 is slidably fitted in the cam groove 6c formed in the cam ring 6. An escape groove 7a is formed in the fourth lens group holding cylinder 7 so that the fourth lens group holding cylinder 7 does not restrict the movement of the cam pin 19. Cam pin 1
9 is inserted in the clearance groove 7a with a gap.

A cam pin 18 is embedded in the second lens group holding cylinder 12. The tip of the cam pin 18 is
It is slidably fitted in a guide groove 5a formed in the interlocking ring 5 and parallel to the optical axis. The central portion of the cam pin 18 is slidably fitted in the cam groove 6b formed in the cam ring 6. The cam groove 6b functions as a cam groove for moving the cam pin 18 in the optical axis direction while rotating the cam pin 18 around the optical axis when the cam ring 6 is stationary (in a focusing operation described later). An escape groove 1e is formed in the inner cylinder 1c so that the inner cylinder 1c of the fixed cylinder 1 does not restrain the movement of the cam pin 18. Similarly, in order to prevent the movement of the cam pin 18 from being constrained by the third lens group holding barrel 8, the relief groove 8b is formed in the third lens group holding barrel 8.
And an escape groove 7b is formed in the fourth lens group holding barrel 7 so that the fourth lens group holding barrel 7 does not restrain the movement of the cam pin 18. The cam pins 18 are inserted into these clearance grooves with a gap.

Next, the operation of the zoom lens barrel will be described.

First, the scaling operation will be described.

When the zoom ring 3 rotates, the interlocking pin 1
The cam ring 6 rotates via 4. At this time, the cam ring 6 has the cam pin 15 fitted in the cam groove 1d.
Moves in the direction of the optical axis while rotating around the optical axis.

When the cam ring 6 moves in the optical axis direction while rotating, the tip end of the cam pin 19 moves along the guide groove 1f. That is, the third lens group G3 held by the third lens group holding barrel 8 moves in the optical axis direction without rotating with respect to the fixed barrel 1. The amount of movement of the third lens group G3 in the optical axis direction with respect to the fixed barrel 1 is equal to the amount of movement of the cam ring 6 itself in the optical axis direction, and the amount of light of the third lens group holding barrel 8 defined by the cam groove 6c of the cam ring 6. This is the amount of movement in the axial direction.

When the cam ring 6 moves in the optical axis direction while rotating, the cam pin 22 of the fourth lens group holding cylinder 7
Although the driving force from the cam ring 6 is applied to the third lens group holding barrel 8, the convex portion 8c of the third lens group holding barrel 8 is guided to the guide groove 7 of the fourth lens group holding barrel 7.
Since it is fitted in c, the fourth lens group holding cylinder 7
It moves in the optical axis direction without rotating with respect to the third lens group holding cylinder 8. That is, the fourth lens group G4 held by the fourth lens group holding cylinder 7 moves in the optical axis direction without rotating with respect to the fixed cylinder 1, similarly to the third lens group G3. The amount of movement of the fourth lens group G4 in the optical axis direction with respect to the fixed barrel 1 is equal to the amount of movement of the cam ring 6 itself in the optical axis direction and the light of the fourth lens group holding barrel 7 defined by the cam groove 6g of the cam ring 6. This is the amount of movement in the axial direction.

When the cam ring 6 rotates and moves in the optical axis direction, the cam pin 1 of the second lens group holding barrel 12 is moved.
Although the driving force from the cam ring 6 acts on the cam ring 8,
Since the tip end portion of 8 is fitted in the guide groove 5a, the second lens group holding barrel 12 moves in the optical axis direction without rotating with respect to the interlocking ring 5. This interlocking ring 5
It is always stationary during zooming. The annular plate 9 is
Since it is pressed against the ball 11 by the coil spring 13, it moves in the optical axis direction while being integrated with the second lens group holding cylinder 12. The amount of movement of the second lens group G2 with respect to the fixed barrel 1 in the optical axis direction is the same as the amount of movement of the cam ring 6 itself in the optical axis direction. This is the amount of movement in the axial direction.

When the cam ring 6 rotates and moves in the direction of the optical axis, the cam ring 6 moves relative to the cam pin 17.
Although a force in the rotation direction is applied from the cam pin 17, the cam pin 17 is fitted in the guide groove 6a, and the cam pin 16 of the third lens group holding barrel 8 is fitted in the cam groove 10b.
The lens group holding barrel 10 moves in the optical axis direction while rotating with respect to the third lens group holding barrel 8. The third lens group holding barrel 8 is moved in the optical axis direction as described above.

That is, the moving amount of the first lens group G1 with respect to the fixed barrel 1 in the optical axis direction is equal to the moving amount of the third lens group holding barrel 8 described above, and the cam groove 10b of the first lens group holding barrel 10.
The amount of movement of the first lens group holding cylinder 10 in the optical axis direction, which is defined by the following equation, is added.

Next, the focusing operation will be described.

When the focus ring 4 rotates, the interlocking ring 5 rotates via the key member 21 and the cam pin 20. When the interlocking ring 5 rotates, the cam pin 18 moves along the cam groove 6b of the cam cylinder 6. The cam barrel 6 is always stationary unless the zoom ring 3 is rotated. That is, the second lens group holding cylinder 12 moves in the optical axis direction while rotating around the optical axis according to the cam groove 6b. Further, the annular plate 9 receives a leftward force in the drawing from the coil spring 13, but a plurality of balls 11 are interposed between the annular plate 9 and the second lens group holding cylinder 12. Therefore, the annular plate 9 is
Even when the lens group holding barrel 12 moves in the optical axis direction while rotating around the optical axis as described above, the second lens group holding barrel 12 is rotated relative to itself (the annular plate 9) while the second lens group holding barrel 12 is rotated.
It moves only in the optical axis direction together with the lens group holding barrel 12. Also, regarding the second lens group holding cylinder 12, the coil spring 1
Since the force from 3 is indirectly applied, the cam pin 18
Moves in the cam groove 6b while being pressed against the side wall of the cam groove 6b. If the cam pin 18 can be moved in the cam groove 6b without rattling, the second lens group G
The movement locus of 2 can be kept constant.

[0031]

According to the present invention, the rattling of the cam mechanism that has been conventionally generated when the lens group holding barrel is driven by a part of the cam mechanism that moves in the optical axis direction while rotating around the optical axis. You can get rid of it.

[0032]

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of an embodiment of a zoom lens barrel according to the present invention.

[Explanation of symbols]

1: fixed cylinder, 1a: mount part, 1b, 6f: outer cylinder part, 1c, 6d: inner cylinder part, 1d, 6b, 6c, 6
g, 10b: cam groove, 1e, 1g, 7a, 7b, 8
b: escape groove, 1f, 3a, 5a, 6a, 7c: guide groove, 2: diaphragm ring, 3: zoom ring, 4: focus ring, 5: interlocking ring, 6: cam ring, 6e: intermediate cylinder part, 7: A fourth lens group holding cylinder,
8: 3rd lens group holding cylinder, 8c: convex part, 9: annular plate, 10: 1st lens group holding cylinder, 10a: sliding part,
11: ball, 12: second lens group holding cylinder, 12
a: annular groove, 13: coil spring, 14, 20: interlocking pin, 15, 16, 17, 18, 19, 22: cam pin, 21: key member

Claims (4)

[Claims] 1. A cam mechanism for moving a lens group holding barrel in the optical axis direction while rotating the lens group holding barrel; and a rattling of the cam mechanism by applying a force in the optical axis direction to the lens group holding barrel. An elastic member, and a low friction contact mechanism that receives the elastic member and contacts the lens group holding cylinder with a frictional resistance lower than a frictional resistance generated when the elastic member directly contacts the lens group holding cylinder. A lens barrel characterized by having. 2. The annular groove is formed around the optical axis on one end surface portion of the lens group holding cylinder according to claim 1, wherein the low friction contact mechanism receives the elastic member. A lens barrel comprising: an annular member incorporated in a groove; an end surface of the annular member; and a rolling member arranged between the bottom surface of the annular groove. 3. The holding member for holding a new lens group different from the lens group held by the lens group holding barrel is provided in the housing barrel, and the elastic member holds the holding member. A lens barrel mounted between the lens group holding barrel and a lens group holding barrel, and applying a force to the lens group holding barrel in a direction such that the lens group holding barrel is separated from the holding portion. 4. The lens barrel according to claim 1, 2 or 3, wherein the elastic member is a coil-shaped spring.