JPS60241006A - Focus adjusting device for lens - Google Patents

Abstract

PURPOSE:To adjust the rotary torque of an adjusting operation member for an elastic member finely and to maintain the state stably rotating a rotary torque adjusting member relatively to a fixed lens barrel and varying energizing force to the focus adjusting operation member. CONSTITUTION:When the focus adjusting operation member 3 fitted around the fixed lens barrel 1 is rotated, a moving cylinder 2 moves forth and back through a roller 8 to adjust the focus. A screw 6 is unclamped and the torque adjusting member 5 engaging the lens barrel 1 with a fine-pitch screw 1b is clamped gradually to left, and then the operation member 3 is applied with thrust-directional energizing force from the elastic member 7 with less friction set beyond the adjusting member 5, so that the rotary torque between the lens barrel 1 and operation member 3 increases gradually. Therefore, a user uses the adjusting member 5 to adjust finely the position where desired torque is obtained and then fixes the screw 6 to maintain the state stably.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a lens focusing device for a photographic camera or the like.

(Prior art and its problems) As a focus adjustment device for a lens in a photographic camera, etc., a focus adjustment operation member rotatably fitted on the outside of a fixed lens barrel is rotated to adjust the focus inside the fixed lens barrel. The 149th type is configured to adjust the focus by moving a part of the lens system.

However, when adjusting the focus using the focus adjustment operation member, the operability changes depending on the rotational torque of the focus adjustment operation member, and on the other hand, the rotational torque of the focus adjustment operation member changes depending on the temperature environment at the time of photographing.

Therefore, it is necessary to adjust this rotational torque, especially when delicate focus adjustment is required, such as with a super-telephoto lens with a shallow depth of field.

Conventionally, it is known that the f-stage rotational torque adjustment of the focus adjustment operating member is performed at a stage in the middle of locking the focus adjustment member. However, since it is originally a locking means, it is not possible to make fine adjustments, and it is in a very unstable state, so even if you do make adjustments, it may not be possible to use it carelessly or due to vibrations during use. There is a drawback that the adjustment may be disrupted.

(Object of the Invention) In view of the above-mentioned circumstances, an object of the present invention is to provide a lens focus adjustment device that can finely adjust the rotational torque of a focus adjustment operation member and stably maintain the adjusted state. .

(Structure of the Invention) The present invention has a focus adjustment operation member rotatably fitted on the outside of a fixed lens barrel, and performs focus adjustment by moving a part of the lens system inside the fixed lens barrel. A rotational torque adjustment member screwed into the fixed lens barrel so as to be relatively rotatable; an elastic member that is pressed against the rotational torque adjustment member and applies a required biasing force to the focus adjustment operation member; and the rotational torque adjustment member is attached to the fixed lens barrel. and a fixing means for fixing the position, and rotates the rotational torque adjustment member relative to the fixed lens barrel to vary the biasing force of the elastic member to the focus adjustment operation member, thereby adjusting the rotational torque of the focus adjustment operation member. It is configured as follows.

(Embodiment of the Invention) The illustrated device is an optical system of a photographic camera, in which a fixed lens barrel L and a fixed lens group L1. L3 is fitted and fixed lens group 1. A movable lens barrel 2 in which a movable lens group L2 is fitted is fitted between L3 so as to be slidable in the optical axis direction. Further, a focus adjustment operation member 3 is fitted to the outside of the fixed lens barrel 1 so as to be freely rotatable. A roller 8 is fixed to the movable lens barrel 2 with screws 9. A guide groove 1a is formed in the fixed lens barrel l, and a cam groove 3a is formed in the focus adjustment operation member 3, and the roller 8 engages with the guide groove 1a and the cam groove 3a. Focus adjustment is performed by rotating the focus adjustment operating member 3 and moving the movable lens barrel 2 back and forth via the rollers 8. The second one is a known focus adjustment means, and since the contact area between members involved in focus adjustment can be reduced, the rotational torque of the focus adjustment operation member 3 can be set to a light state.

There is a fine pitch screw lb on the outside of the fixed lens barrel l.
A rotational torque adjusting member 5 having a screw 5a having the same pitch as the screw 1b is rotatably engaged with the fixed lens barrel l.

Further, an elastic member 7 made of rubber or the like with low friction is provided between the focus adjustment operation member 3 and the rotational torque adjustment member 5.

Portions 3b and 5b where the focus adjustment operation member 3 and the rotational torque adjustment member 5 come into contact with the elastic member 7 are bonded with a low-friction tape or coated with a friction-preventing coating to improve the operation feel. Further, a fixing screw 6 for fixing the rotational torque adjustment member 5 at an arbitrary position is engaged with the rotational torque adjustment member 5.

In FIG. 1, the focus adjustment operating member 3 and the rotational torque adjustment member 5 are in light contact with the elastic member 7, and the rotational torque adjustment member 5 is fixed by a fixing screw 6. At this time, since the focus adjustment operation member 3 does not receive much urging force from the elastic member 7, the rotational torque of the focus adjustment operation member 3 is in a light state. To adjust the rotational torque, first loosen the fixing screw 6, and then gradually screw in the rotational torque adjustment member 5 to the left in FIG. Under the urging force of , the frictional force between the fixed lens barrel l and the focus adjustment operation member 3 increases, and the rotational torque becomes heavier little by little. The rotational torque adjustment member 5 is moved to a position where the rotational torque desired by the user is obtained.
is adjusted, and the rotational torque adjusting member 5 is fixed to the fixed lens barrel l using the fixing screw 6. FIG. 2 shows the state in which the required rotational torque has been adjusted by the following operations.

Note that the elastic member 7 may be a plate spring made of metal or resin as shown in FIG. 3, or in FIGS. Yes, but
It may be fixed to the focus adjustment operation member 3 or the rotational torque adjustment member 5, or may be molded integrally with the focus adjustment operation member 3 or the rotational torque adjustment member 5.

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. 4. Further, FIG. 5 shows a state in which the fixing screw 6 is embedded in the fixed lens barrel l or the rotational torque adjusting member 5 so that it does not come into contact with the fixing screw 6 inadvertently during transportation or focus adjustment operations.

(Effects of the Invention) Since the present invention is configured as described above, by operating the rotational torque adjustment member, the rotational torque of the focus adjustment operation member can be arbitrarily changed, and after the rotational torque adjustment member is changed by the fixing means. It can be stably maintained in this state. In addition, by making the threaded portion between the rotational torque adjustment member and the fixed lens barrel into a screw state with a fine pitch, fine rotational torque adjustment can be performed accurately, and the fixing means for fixing the rotational torque adjustment member can be attached to the fixed mirror. By embedding it in either the cylinder or the rotational torque adjusting member, the fixing means will not be touched inadvertently, so the adjusted position can be maintained more reliably.

[Brief explanation of the drawing]

1 and 2 are partial side sectional views showing one embodiment of a lens barrel having a focus adjustment device according to the present invention, FIG. 3 is a side view showing an example of its elastic member, and FIG. FIG. 5 is an enlarged side sectional view of a fixing screw portion showing another embodiment of the present invention. l...Fixed lens barrel 1b...Threaded part 2...Movable lens barrel 3...Focus adjustment operation member 3b...
・Contact part 5...Rotational torque adjustment member 5a...Threaded part 5b...Contact part 6...Fixing screw 7...
Elastic member 8... Roller 9... Screw Ll, L3... Fixed lens group L2... Moving lens group Patent applicant Asahi Optical Co., Ltd.

Claims (6)

[Claims] (1) In a device that has a focus adjustment operation member that is rotatably fitted on the outside of a fixed lens barrel and that adjusts the focus by moving a part of the lens system inside the fixed lens barrel, a rotational torque adjustment member that is movably screwed together, an elastic member that is pressed against the rotational torque adjustment member and applies a required biasing force to the focus adjustment operation member, and a fixing means that fixes the rotational torque adjustment member in position on the fixed lens barrel. and configured to adjust the rotational torque of the focus adjustment operation member by rotating the rotation torque adjustment member relative to the fixed lens barrel to vary the urging force of the elastic member to the focus adjustment operation member. Features a lens focus adjustment device. (2) A focusing device for a lens according to claim (1), wherein a biasing force of the elastic member is applied to the focusing operation member in a thrust direction. (3) The lens focusing device according to claim 1 or 2, characterized in that a plate spring is used as the elastic member. (4) A focusing device for a lens as set forth in claim (1) or (2), wherein rubber with low friction is used as the elastic member. (5) The elastic member is integrally resin-molded with either the focus adjustment operation member or the rotational torque adjustment member.
2) The lens focus adjustment device described in item 2). (6) The fixing means is a screw, and is embedded in either the fixed lens barrel or the rotational torque adjustment member;
A lens focusing device according to claim (1), characterized in that: