JPH10333015A - Gravity operation preventing mechanism for zoom lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a gravity operation, in a state where a zooming operation is kept, with simple structure and a small number of parts by providing a holding part, which is engaged with a zooming operation ring at a holding position, so as to inhibit the movement of the zooming operation ring, but not with the zooming operation ring at an operating position SOLUTION: A photographer operates the zooming operation ring 38 with his or her fingers, to complete a zooming adjustment and when he or she wants to keep this zooming state, he or she moves the zooming operation ring 38 to the side of a mount 22 by the operation of the fingers, in the state where the zooming adjustment is made. A ball 64 is changed from the engagement with a rear click groove 68 to that with a front click groove 66 and the holding part 32 and a zoom holding ring 40 come into frictional contact with each other. In such a case, the zoom holding ring 40 can be displaced between the frictional contact possible position and noncontact position of the end part on the side of the mount 22 of the ring 40 with the zoom holding part 32. Then, the frictional contact state of the holding part 32 with the zoom holding ring 40 is kept because the ball 64 is engaged with the front click 66.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mechanism for preventing a self-weight operation of a zoom lens, that is, to prevent a zoom operation from being performed by gravity acting on a constituent member of the zoom lens when the zoom lens is set to be inclined. The present invention relates to a self-weight operation preventing mechanism for a zoom lens.

[0002]

2. Description of the Related Art When a camera equipped with a zoom lens is set obliquely upward or obliquely downward for photographing, or when the zoom lens is carried vertically downward, any operation force is applied to the zoom operation ring of the zoom lens. In some cases, the zoom operation may be performed by gravity acting on the components of the zoom lens even though the zoom lens is not added. This malfunction is
There is a problem that the focal length fluctuates to prevent the next quick shooting, and that the entire length of the zoom lens becomes longer, so that the tip portion collides with an object or is immersed in water. In order to solve such a problem of the zoom lens, the gap between the sliding fittings is reduced to increase the frictional resistance, and a highly viscous grease is used for the sliding portion.

However, even with such measures, the prevention of the self-weight operation of the zoom lens is not complete, and the self-weight operation is mechanically prevented. That is, as shown in FIGS. 5 and 6, in the rectilinear zoom lens 100, the holding operation ring 104 is screwed to the mount-side end of the zoom operation ring 102. The holding operation ring 104 is provided with a rotation range limiting member 108 that engages with a groove 106 formed in the zoom operation ring 102 so as to extend in the circumferential direction. Mount side of zoom operation ring 102 (right side in the drawing)
Is formed with a conical surface 112 having a central recess. On the surface of the holding operation ring 104 facing away from the mount, a conical surface 120 having a central recess is formed. In a space extending in the circumferential direction formed by the conical surfaces 112 and 120, a friction ring 130 having a C-shaped cross section in a plane perpendicular to the optical axis and facing the fixed cylinder 126 is disposed. Felt is pasted on.
Friction ring 126 abuts conical surfaces 112 and 120 under its own biasing force.

[0004] The linear zoom lens 100 having the above-described configuration.
In order to prevent the self-weight operation, as shown in FIG. 6, the holding operation ring 104 is rotated in a direction to increase the screwing amount with the zoom operation ring 102 so that the conical surfaces 112 and 120 are brought closer to each other. Then, the friction ring 126 is pushed out of the space created by these members and pressed against the outer surface of the fixed barrel 126 to fix the zoom operation ring 102 to the fixed barrel 126.

[0005]

In the conventional self-weight operation preventing mechanism shown in FIG. 5 and FIG.
Since the holding operation ring 104 and the holding operation ring 104 are separate bodies, there is a problem that the left hand of the zoom operation must be changed from the zoom operation ring 102 to the holding operation ring 104 in order to prevent the self-weight operation from the zoom operation. The holding force for fixing and holding the zoom operation ring 102 to the fixed barrel 126 is as follows:
Since the holding operation ring 104 changes depending on the amount by which the holding operation ring 104 is screwed to the zoom operation ring 102, the holding force is variable,
There is a problem in that it is difficult to quickly obtain a holding force for optimally holding the image, that is, a fixing force for fixing and releasing the fixing for the next zoom operation.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems with respect to the conventional mechanism for preventing the self-weight operation of a zoom lens, and has a simple structure, a small number of parts, and a self-weight while zooming. An object of the present invention is to provide a self-weight operation prevention mechanism of a zoom lens that can be operated and released to prevent operation, has good operability, and can reliably obtain an optimal holding force for preventing self-weight operation. And

[0007]

According to the present invention, there is provided a zoom lens having a fixed barrel fixed to a camera body and a rotary zoom operation ring, wherein the first zoom operation ring is substantially integral with the rotary zoom operation ring. The first zoom operating ring is integral with the first zoom operating ring but is displaceable in the optical axis direction, and the second zoom operating ring is different from the second zoom operating ring in the optical axis direction. The first zoom operating ring, which is substantially integral with the fixed cylinder and is in the holding position, with the conversion holding means holding the holding position and the operating position with a holding force that can be exceeded by the operating force of the finger. A self-weighting operation prevention mechanism for a zoom lens, comprising: a holding portion that engages to prevent movement of a first zoom operation ring and does not engage with the first zoom operation ring at an operation position.

An embodiment of the present invention is as follows.
A buffer is provided on one of the first zoom operating ring and the holding portion. The conversion holding means is a click mechanism including a ball and a leaf spring. The conversion holding means is a click mechanism including a leaf spring.

[0009]

Preferred embodiments of the present invention will be described below in detail with reference to the drawings. As shown in FIG. 3, the zoom lens 1 of the embodiment has a length of 28 to 105 m.
m, F: 2.8 A rotary zoom lens having an optical system including a first lens group 4, a second lens group 6, a third lens group 8, and a fourth lens group 10. Zoom lens 1
As shown in FIGS. 1, 2, and 3, a fixed cylinder 26 integrated with the mount 22 mounted on the camera body, a zoom operation unit 30 disposed outside the fixed cylinder 26, and a zoom operation unit 30 And a holding portion 32 that holds the zoom at that position by engaging with the zoom lens.

The zoom operation unit 30 is shown in FIGS.
As shown in the figure, a zoom operation ring 38 operated by the photographer with a finger
And a first zoom operation ring 36 integrated with the zoom operation ring 38
And a zoom holding ring 40 also integrated with the zoom operation ring 38.
And a second zoom operating ring 37 for moving the optical system for zoom adjustment. Zoom holding ring 40
The end of the mount 22 can be shifted between a position where frictional contact with the zoom holding portion 32 is possible and a position where the end is not in contact with the zoom holding portion 32. A guide rail 50 extending in the optical axis direction is formed on the second zoom operating ring 37, and a linear groove 52 formed on the zoom holding ring 40 is engaged with the guide rail 50. Therefore, the zoom operation ring 38 and the second zoom operation ring 37 rotate integrally with each other in the rotation direction, but can relatively freely move in the optical axis direction. The zoom holding ring 40 has a pair of front click grooves 66 and rear click grooves 68 that are adjacent to each other and have the gentle protrusion 44 interposed therebetween. A plurality of balls 64 urged outward by a leaf spring 62 attached by the above-mentioned method engage with the front click groove 66 or the rear click 68. A felt is attached to the outer surface of the holding portion 32 in order to increase the frictional force with the zoom holding ring 40 and make the sliding with the zoom holding ring 40 smooth.

In the above-described configuration, when the photographer operates the zoom operation ring 38 with a finger to complete the zoom adjustment and wants to maintain the zoom state, the user can operate the zoom operation ring 38 while operating the finger while maintaining the zoom adjustment state. The zoom operation ring 38 is moved to the mount 22 side. The ball 64 is in the rear click groove 68
From the engagement of the front click groove 66 to the engagement of the holding portion 3
2 and the zoom holding ring 40 are in frictional contact. The state of this frictional contact between the holding part 32 and the zoom holding ring 40
4 is retained by engaging the front click 66,
It is held until a torque of, for example, 6 kg · cm or more is applied to the zoom operation ring 38. The above-described zoom holding state is released by applying a torque of 6 kg · cm or more to the zoom operation ring 38, and a normal zoom operation state is set. As a modification of the above-described embodiment, the chevron portion corresponding to the ball may be formed in the leaf spring 50 without using the ball 52.

[0012]

According to the mechanism for preventing the self-weight operation of the zoom lens of the present invention, the structure is simple, the number of parts is small, and the manufacturing cost is low. It can be performed and the operability is good,
Further, an optimal holding force for preventing the self-weight operation can be reliably obtained, and an effect of excellent operability can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view of a non-operation state of a self-weight operation prevention mechanism of a zoom lens according to an embodiment of the present invention.

FIG. 2 is a sectional view showing an operation state of a self-weight operation preventing mechanism of the zoom lens according to the embodiment of the present invention shown in FIG. 1;

FIG. 3 is a cross-sectional view of a zoom lens having a self-weight operation preventing mechanism according to an embodiment of the present invention.

FIG. 4 is an exploded view of a self-weight operation preventing mechanism of the zoom lens according to the embodiment of the present invention.

FIG. 5 is a cross-sectional view of a conventional self-weight operation preventing mechanism of a zoom lens in a non-operation state.

FIG. 6 is a cross-sectional view of an operation state of a conventional self-weight operation prevention mechanism of a zoom lens.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Zoom lens 22 Mount 26 Fixed cylinder 30 Zoom operation part 32 Holding part 40 Zoom holding ring 64 Ball 66 Front click groove 68 Rear click groove

Claims (4)

[Claims] 1. A zoom lens having a fixed barrel fixed to a camera body and a rotary zoom operation ring, a first zoom operation ring substantially integral with the rotary zoom operation ring, and a rotation with the first zoom operation ring. A second zoom operating ring, the direction of which is integral but displaceable in the optical axis direction; and the first zoom operating ring with respect to the second zoom operating ring.
Conversion holding means for holding with a holding force that can be exceeded by an operating force of a finger at a different holding position and an operating position in the optical axis direction; and A first zoom operating ring that is engaged with the first zoom operating ring to prevent movement of the first zoom operating ring, and has a holding portion that does not engage with the first zoom operating ring at the operating position; mechanism. 2. The self-weight operation preventing mechanism for a zoom lens according to claim 1, wherein a buffer material is disposed on one of the first zoom operating ring and the holding portion. 3. The mechanism according to claim 1, wherein said conversion holding means is a click mechanism including a ball and a leaf spring. 4. The mechanism according to claim 1, wherein said conversion holding means is a click mechanism including a leaf spring.