JP2000321477A - Lens barrel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a lens barrel which is switched in focus-free mode in the operating direction of a manual adjusting cylinder and can manually be adjusted only when a manual force as 2nd power is obtained. SOLUTION: An interlocking part 11a of the manual adjustment cylinder is arranged in a gap 10a of a clutch ring 10 and springs 12a and 12b and balls 13a and 13b are inserted into the gap at both its ends in the circumferential direction. A slope is so formed that as the balls 13a and 13b move in the spring- side circumferential directions, the gap becomes narrower. When the manual adjustment cylinder is not operated, the balls 13a and 13b are pressed against the end surface of the interlocking part 11a with nearly equal energizing forces by the springs 12a and 12b and then the lens barrel is composed of the outer peripheral surface 9b of a driving cylinder, the elastic forces of the springs 12a and 12b, the diameter of the balls, the slope shape, and the slide resistance between a hold cylinder 7 and the clutch ring 10 so that the balls do not intrude in the tilt surface of the gap 10a and the outer peripheral surface 9b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system camera, and more particularly to a lens barrel of an interchangeable lens of a single-lens reflex camera, and more particularly to a lens barrel of an AF single-lens reflex camera capable of manually adjusting a distance ring.

[0002]

2. Description of the Related Art In a so-called automatic focus adjustment (hereinafter referred to as AF) camera in which a distance adjusting cylinder is driven by a motor which is a first power, manual focus adjustment (hereinafter referred to as an M) which is a second power.
When performing F), a switching mechanism for AF and MF is provided, and it is common to operate this to perform manual adjustment. When such a lens barrel is driven by a motor of the first power, the distance adjustment barrel is rotated by the first power.
There is a problem that the photographer carelessly touches the adjusting cylinder and affects the focusing operation, and there is a problem in holding the camera and the lens barrel in the photographing state with respect to the adjusting cylinder. For this reason, the manual adjustment cylinder and the distance adjustment cylinder are separated, and the manual adjustment cylinder is slid in the optical axis direction of the lens barrel, or a separate switching clutch is installed,
A method has been proposed in which the manual adjustment cylinder is shut off from the distance adjustment cylinder at the time of AF operation, and the manual adjustment cylinder does not rotate even when the distance adjustment cylinder operates (this is called a focus-free and commercialized).

[0003]

However, in any of the above-mentioned focus-free systems, the switching direction is different from the operation direction of the manual adjustment cylinder, so that the switching operation lacks smoothness. For this reason, a lens barrel that can be manually adjusted only when a manual force, which is the second power, is obtained for these switching operations has been desired.

[0004]

Therefore, in the present invention, a clutch mechanism comprising an intermediate ring and its accessories is provided between a drive cylinder and a manual adjustment cylinder interlocked with a distance adjustment cylinder, and when the manual adjustment cylinder is not operated. The intermediate ring is held in a neutral position with respect to the manual adjustment barrel by the accessory, and the drive ring idles with respect to the accessory. The intermediate ring, accessory and drive cylinder are connected and integrated by acting on the object, so that the manual adjustment cylinder is configured to operate.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS When the manual adjustment cylinder is not rotated, the clutch mechanism is in the released state. In the AF mode, the manual adjustment cylinder does not rotate even if the AF operation is performed. And MF
In the mode, when manual operation power is applied to the manual adjustment cylinder, the clutch mechanism is connected by the manual force, and the rotational force rotates the drive cylinder, and as a result, focus adjustment is performed.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The best embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view of a lens barrel on which the clutch mechanism of the present invention is mounted, and FIG. 2 is a cross-sectional view of a main part of the clutch mechanism taken along line AA. In the drawings, the same members are denoted by the same reference numerals.

In the sectional view of the lens barrel shown in FIG. 1, there are a front lens unit L1 and a rear lens unit L2 centered on the optical axis L0, and by moving the front lens unit L1 straight with respect to the rear lens unit L2, 3 shows an example of a lens barrel capable of adjusting focus.

The front lens unit L1 is held by a holding frame 1, and the rear lens unit L2 is held by a holding frame 2.
The helicoid portion 3a of the distance adjusting cylinder 3 to which the first holding frame 1 is fixed is engaged with the helicoid portion 4a of the moving cylinder 4, and the moving cylinder 4 and the distance adjusting cylinder 3 move straight with the fixed cylinder 5 integrally. You can do it. The movement of the inner tooth tube 6 in the optical axis direction is restricted by the protrusion 7a of the holding tube 7 fixed to the fixed tube 5, but the inner tooth tube 6 is freely rotatably supported. Internal teeth 6a are formed with internal teeth 6a on the inner diameter side, and mesh with a pinion 8 that rotates via a gear train that rotates by receiving a rotational force from a motor in the camera or a motor in the lens (not shown). . The gear train (not shown) includes a mechanism for transmitting power during AF and a mechanism for disconnecting during MF. The drive cylinder 9 integrated with the inner tooth tube 6 includes:
Since the interlocking lever 3b on which the distance adjusting cylinder 3 is fixed is fitted into the inner straight lever groove 9a, the rotation of the internal tooth tube 6 can be transmitted to the distance adjusting cylinder 3 and the moving cylinder 4 and the distance adjusting cylinder 3 can be transmitted. Changes the relative angle of the distance adjustment barrel 3 with respect to the movable barrel 4 and the straight-moving position of the front lens unit L1 of the holding frame 1 to adjust the focus of the lens barrel.

The manual adjustment cylinder 11 fitted to the clutch ring 10 is supported by the projection 7b so as to be freely rotatable while its movement in the optical axis direction is restricted. A sliding member 10 g is adhered to the outer periphery of the clutch ring 10,
And an appropriate sliding relationship is maintained.

FIG. 2 shows the arrangement of the drive cylinder 9, the clutch ring 10, and the manual adjustment cylinder 11 as viewed from the axial direction. An interlocking portion 11a of the manual adjustment cylinder 11 is disposed in a gap 10a of the clutch ring 10, and springs 12a, 12b, balls 13a, 13
b is inserted. The inclination is formed so that the gap becomes narrower as each ball advances in the spring-side circumferential direction. When the manual adjustment cylinder 11 is not operated, the balls 13a and 13b are pressed against the end surfaces of the interlocking portion 11a by the same urging force by the urging force of the springs, respectively.
So that the ball does not cut into the inclined surface and the outer peripheral surface 9b,
The outer peripheral surface 9b of the drive cylinder 9, the elastic force of the springs 12a and 12b,
Ball diameter, inclined shape, holding cylinder 7 and clutch ring 10
And the like.

Next, the operation will be described. At the time of AF, the manual adjustment cylinder 11 is held by hand, and the clutch ring 10 is held at a position where the ball does not bite into the inclined surface and the outer peripheral surface 9b of the clutch ring 10 due to the urging force of the spring. . Therefore, no holding force acts between the ball and the outer peripheral surface 9b, and the driving cylinder 9 slides with respect to the ball.

At the time of MF, when the manual adjustment cylinder 11 is turned in the direction of the arrow, the clutch ring 10 receives a rotational force by urging the end face 10b via the spring 12a and the ball 13a. Due to the inertial force and the sliding resistance between the clutch ring 10 and the holding cylinder 7, the clutch ring 10 moves slightly behind the ball. As a result, the ball 13a is inclined by the inclined surface
As a result, the clutch ring 10 and the driving cylinder 9 are integrated and turned in the direction of the arrow. When the rotation of the manual adjustment cylinder 11 is stopped, the clutch ring 10 and the driving cylinder 9 stop with a delay due to the inertial force. As a result, the ball 13a and the interlocking portion 11a are separated from each other, and the spring 12
By a, the biting state of the ball is released. In addition,
At the time of MF, in the gear unit (not shown), the interlock between the motor and the pinion 8 is interrupted. Therefore, even if the internal tooth tube 6 rotates, the motor does not rotate and does not become a load.

FIGS. 3 and 4 are a perspective view and a sectional view of another embodiment of the present invention, in which a clutch ring and a manual adjustment cylinder are modified.

In FIG. 3, projections 10e and 10f are formed on the clutch ring 10d. The two clutch plates 11c and 11d are formed integrally with the manual adjustment cylinder 11b, and have elasticity in relation to the constituent material and the shape.

This clutch mechanism is configured as shown in FIG. 4, and when no manual operation force is applied, the bottom surfaces 11f, 11
g has a slight gap with the outer peripheral surface 9b of the driving cylinder 9c. When the manual adjustment cylinder 11b is rotated in the direction of the arrow 12, the inertia of the clutch ring 10d and the sliding resistance between the clutch ring and the fixed cylinder 5 receive the resistance of the projection 10e. I do. Therefore, the bottom surface 11f of the projection 10e presses the outer peripheral surface of the driving cylinder 9c to be frictionally coupled, and the driving cylinder 9c and the manual adjustment cylinder 11b rotate integrally. Next, when the rotation is stopped, the clutch ring 10d stops with a slight delay. Therefore, a restoring force acts on the manual adjustment cylinder 11b in the direction opposite to the direction of the arrow 13 due to the elastic force, and the pressing force on the outer peripheral surface 9b is released.

As described above, the ball is used to connect the clutch ring and the drive cylinder.
Of course, it may be a cylindrical roller or the like, and may not be a rolling element, but may be a wedge or the like. In addition, 1
Although only a set of clutch units is shown, a plurality of clutch units may be provided.

In the description, the clutch is pressed so as to act in the radial direction. However, the clutch may be pressed in the optical axis direction.
The mechanical relationship between the clutch ring and the manual adjustment cylinder may be reversed.

[0019]

As described above, according to the structure of the present invention, the clutch can be interlocked and disengaged in any angle direction, and it is not necessary to move the manual adjustment cylinder back and forth in the optical axis direction. Therefore, a compact configuration can be achieved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a lens barrel according to an embodiment.

FIG. 2 is a sectional view taken along line AA of the embodiment.

FIG. 3 is a perspective view showing a clutch mechanism of another embodiment.

FIG. 4 is a sectional view of the clutch mechanism shown in FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Holding frame 2 Holding frame 3 Distance adjusting cylinder 3b Interlocking lever 4 Moving cylinder 5 Fixed cylinder 6 Internal tooth tube 7 Holding cylinder 8 Pinion 9 Drive cylinder 10 Clutch ring 11 Manual adjustment cylinder

Claims (2)

[Claims] 1. A lens barrel having a distance adjustment barrel whose lens position on the optical axis can be moved by a motor power as a first power, regardless of the driving of the distance adjustment cylinder by the first power. A lens barrel having a clutch mechanism that is connected to the distance adjusting cylinder only when the second power is obtained and enables the distance adjusting cylinder to be driven by the second power. 2. The method according to claim 1, wherein when the second power is obtained, the clutch mechanism is operated by a starting force of the power, and the distance can be adjusted in accordance with the starting direction. Lens barrel.