JPH0677093B2 - Lens focus adjuster - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a focus adjusting device for a lens in a camera for photography.

(Prior Art and its Problems) As a focus adjusting device for a lens in a camera for photography, a focus adjusting operation member rotatably fitted to the outside of the fixed lens barrel is used to rotate the focus adjusting device. Generally, a part of the lens system is moved to adjust the focus. However, in the focus adjustment by the focus adjustment operation member, the operability changes according to the rotation torque, while the rotation torque of the focus adjustment operation member fluctuates depending on the temperature environment at the time of photographing. Therefore, it is necessary to adjust the rotation torque especially when a delicate focus adjustment is required such as a super telephoto lens having a shallow depth of field.

Conventionally, as the rotation torque adjusting means of the focus adjusting operation member, there is known one that is performed during the stage of locking the focus adjusting member. However, since it is originally a locking mechanism, it cannot be finely adjusted, and because it looks like an extremely unstable state, even if you make adjustments carefully, you can adjust the locking mechanism carelessly or by vibration during use. There is a drawback that it will collapse.

(Object of the Invention) In view of the above circumstances, an object of the present invention is to provide a focus adjusting device for a lens, which can finely adjust the rotational torque of the focus adjusting operating member and can stably maintain the adjustment state. .

(Structure of the Invention) A lens focus adjusting device according to the present invention has a focus adjusting operation member rotatably fitted to the outside of a fixed lens barrel, and moves a part of the lens system in the fixed lens barrel. In the focus adjustment operation member, a flange portion provided to be orthogonal to the optical axis of the lens system and a fixed lens barrel are screwed into the focus adjustment operation member so as to be rotatable relative to each other, and the lens A rotary torque adjusting member that is movable in the optical axis direction of the system and has a pressing portion that has a pressing portion that faces the flange portion, and is interposed between the pressing portion of the rotational torque adjusting member and the flange portion. An elastic member, and the rotation torque adjusting member is rotated relative to the fixed lens barrel and moved in the optical axis direction to adjust elastic deformation of the elastic member, thereby performing the focus adjustment operation. The feature is that the rotation torque of the member is adjusted. is doing.

(Embodiment of the Invention) The illustrated apparatus is an optical system of a camera for photography, in which fixed lens groups L1 and L3 are fitted to a fixed lens barrel 1, and a fixed lens group L
A moving lens barrel 2 in which a moving lens unit L2 is fitted between 1 and L3
, Are fitted so as to be slidable in the optical axis direction. A focus adjustment operating member 3 is rotatably fitted on the outer side of the fixed lens barrel 1. A roller 8 is fixed to the movable lens barrel 2 with a screw 9. A guide groove 1a is formed in the fixed barrel 1 and a cam groove 3a is formed in the focus adjusting operation member 3, and a roller 8 is engaged with the guide groove 1a and the cam groove 3a. Focus adjustment
By rotating the focus adjustment operation member 3, the movable lens barrel 2 is moved back and forth via the roller 8. The above is the known focus adjusting means, and since the contact area between the members related to the focus adjustment can be reduced, the rotational torque of the focus adjusting operation member 3 can be set to a light state.

A screw 1b having a fine pitch is provided on the outer side of the fixed lens barrel 1, and a rotational torque adjusting member 5 having a screw 5a having the same pitch as the screw 1b is engaged with the fixed lens barrel 1 so as to be freely rotationally movable. An elastic member 7 made of rubber or the like with less friction is provided between the focus adjustment operation member 3 and the rotation torque adjustment member 5. The portions 3b and 5b where the focus adjusting operation member 3 and the rotation torque adjusting member 5 come into contact with the elastic member 7 are provided with a tape having less friction or a coating for preventing friction in order to improve the operation feeling. Further, a fixing screw 6 for fixing the rotation torque adjusting member 5 at an arbitrary position is engaged with the rotation torque adjusting member 5.

In FIG. 1, the rotation torque adjusting member 5 is fixed by a fixing screw 6 in a state where the focus adjusting operation member 3 and the rotation torque adjusting member 5 are in slight contact with the elastic member 7. At this time, since the focus adjustment operating member 3 is not so much urged by the elastic member 7, the rotational torque of the focus adjustment operating member 3 is in a light state. In order to adjust the rotation torque, first, the fixing screw 6 is loosened, and the rotation torque adjusting member 5 is gradually screwed to the left in FIG. 1, so that the focus adjusting operation member 3 gradually moves from the elastic member 7 in the thrust direction. The thrust frictional force between the fixed lens barrel 1 and the focus adjustment operating member 3 increases due to the urging force of, and the rotational torque gradually increases. The rotation torque adjusting member 5 is adjusted to a position where the rotation torque desired by the user is obtained, and the rotation torque adjusting member 5 is fixed to the fixed barrel 1 by the fixing screw 6. FIG. 2 shows a state in which the required rotational torque is adjusted by the above operation.

The elastic member 7 may be a metal or resin leaf spring as shown in FIG. 3 or, in FIGS. 1 and 2, the elastic member 7 is rotatably provided outside the focus adjustment operating member 3. But
It may be fixed to the focus adjustment operation member 3 or the rotation torque adjustment member 5, or may be integrally molded with the focus adjustment operation member 3 or the rotation torque adjustment member 5 by resin molding.

Further, in FIGS. 1 and 2, the fixing screw 6 is engaged with the rotational torque adjusting member 5, but the fixing screw 6 may be engaged with the fixed lens barrel 1 as shown in FIG. Further, FIG. 5 shows a state in which the fixing screw 6 is embedded in the fixed lens barrel 1 or the rotation torque adjusting member 5 so as not to come into contact with the fixing screw 6 carelessly during transportation or focus adjustment operation.

(Effects of the Invention) Since the present invention is configured as described above, the rotational torque of the focus adjustment operating member can be arbitrarily changed by operating the rotational torque adjusting member, and after the rotational torque adjusting member is changed by the fixing means. The state can be stably maintained. Further, by finely pitching the threaded portion between the rotation torque adjusting member and the fixed lens barrel, the fine rotation torque can be adjusted accurately, and the fixing means for fixing the rotation torque adjusting member is fixed to the fixed mirror. By embedding it in either the cylinder or the rotating torque adjusting member, it is possible to prevent the fixing means from being inadvertently touched, so that the adjusted position can be maintained more reliably.

[Brief description of drawings]

1 and 2 are partial side sectional views showing an embodiment of a lens barrel having a focus adjusting device according to the present invention, FIG. 3 is a side view showing an example of an elastic member thereof, and FIG. FIG. 5 is an enlarged side sectional view showing a fixing screw portion showing another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1 ... Fixed barrel, 1b ... Screw part 2 ... Moving barrel 3, 3 ... Focus adjustment operating member 3b ... Contact part, 5 ... Rotation torque adjusting member 5a ... Screw part, 5b ... Contact part 6 ... Fixing screw, 7 ... Elasticity Member 8 ... Roller, 9 ... Screw L1, L3 ... Fixed lens group L2 ... Moving lens group

Claims (5)

[Claims] 1. A focus adjustment operation member rotatably fitted to the outside of a fixed lens barrel, wherein a part of a lens system in the fixed lens barrel is moved to perform focus adjustment. A flange portion provided so as to be orthogonal to the optical axis of the lens system and an operation member screwed into the fixed lens barrel so as to be rotatable relative to the flange portion, and is movable in the optical axis direction of the lens system. A rotary torque adjusting member having a pressing portion facing the flange portion; and an elastic member interposed between the pressing portion of the rotating torque adjusting member and the flange portion, wherein the rotary torque adjusting member is fixed to the fixing member. By rotating the lens barrel relative to the lens barrel and moving the lens barrel in the optical axis direction, the elastic deformation of the elastic member in the thrust direction is adjusted, whereby the rotational torque of the focus adjustment operating member is adjusted. A lens focus adjustment device. 2. The lens focus adjusting device according to claim 1, wherein a leaf spring is used as the elastic member. 3. The lens focus adjusting device according to claim 1, wherein rubber having a low friction is used as the elastic member. 4. The focus adjustment of a lens according to claim 1, wherein the elastic member is integrally resin-molded with one of the focus adjustment operation member and the rotation torque adjustment member. apparatus. 5. The lens focus adjusting device according to claim 1, wherein the fixing means is a screw and is embedded in either the fixed lens barrel or the rotating torque adjusting member. .