JPH023003A - Focusing mechanism for lens-barrel of lens - Google Patents

Abstract

PURPOSE:To execute coarse and fine adjustments at the time of focusing without necessitating a switching operation by using two systems of a first transfer system having some clearance against the rotating direction and a second transfer system larger in reduction ratio than that of the first transfer system through a slip mechanism. CONSTITUTION:The title mechanism is provided with the first transfer system (gears 11, 17 and 15) being in a connecting relation having some clearance against the rotating direction, and the second transfer system (pulleys 10, 14 and a belt 18) in which a slip mechanism is interposed, and which has a larger reduction ratio than that of the first transfer system. Accordingly, the coarse adjustment is applied to the transfer system of the gears 11, 17 and 15 which follow a rotation angle of an operating ring 3, a slip of a belt transfer system is released by rotating the operating ring 3 in the reverse direction, and the fine adjustment can be executed through the belt transfer system. In such a way, the effect of coarse and fine adjustments at the time of focusing can be obtained without necessitating a switching operation against only the rotation of a single motive source.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a manual focusing mechanism for a lens barrel of a camera, and more particularly to a focusing mechanism that allows coarse and fine adjustment.

[Prior Art] Conventionally, a focusing mechanism for a lens barrel capable of coarse and fine adjustment has two independent operations, one for coarse adjustment and one for fine adjustment, as described in, for example, Japanese Utility Model Application Publication No. 60-82180. Those having members, Japanese Utility Model Publication No. 54-8740, Publication of Utility Model Publication No. 55-10963, JP-A-58-38
As described in Japanese Patent No. 907, there was a device configured such that coarse adjustment could be performed by moving a single operating member in the optical axis direction, and fine adjustment could be performed by rotating it.

[Problems to be Solved by the Invention] However, in the conventional technology described above, which has two independent operation members for coarse adjustment and fine adjustment, since the operation members are provided independently for each, it is necessary to change the operation member during focusing. Moreover, the operation method is different for coarse adjustment and fine adjustment due to the movement operation in the optical axis direction and the rotation operation, so the operation is complicated, and the operation is complicated. Since both movement and rotation are used in the focus lens, the zoom lens barrel is configured so that the movement of a single member in the optical axis direction is used for zooming, and focusing is performed only by the rotation of the same operating member. There were some problems, such as not being able to be applied.

The present invention attempts to solve these problems. That is, an object of the present invention is to provide a focusing mechanism for a lens barrel that allows coarse and fine adjustment during focusing without requiring a complicated structure and without requiring a switching operation for only the rotation of a single driving source. That is.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a lens barrel having a focusing mechanism, in which rotation on the driving side with respect to the moving mechanism for moving the focusing lens in the optical axis direction is provided. As a power transmission mechanism for transmitting the power, the first transmission system has a connection relationship with some play in the rotation direction, and the second transmission system has a slip mechanism interposed therebetween, and It is assumed that the second transmission system has a larger reduction ratio than the first transmission system.

[Function] According to the present invention, as a power transmission mechanism for transmitting the rotation of the driving side to the movement mechanism that moves the focus lens in the optical axis direction, a slight play in the rotation direction is provided. The system uses two transmission systems: a first transmission system that has a connection relationship with Two different focus lens movement amounts can be obtained for only the rotation of one driving source without requiring a switching operation.

[Embodiment] The drawings show an embodiment of the present invention, in which Fig. 1 shows a cross section of a lens barrel, Fig. 2 shows a main part of a power transmission system, and Fig. 3 shows an A in Fig. 2. -A cross section, FIG. 4 shows the operation.

In FIG. 1, 1 is a fixed barrel, 2 is a lens, 3 is an operating ring, 4 is a focus barrel, and 5 is a focus lens.

In FIG. 2, 6 is a front base plate, and 7 is a rear base plate, each of which is fixed to the fixed tube 1 shown in FIG.

That is, the fixed tube 1 holds the lens 2, and its outer tube portion 1
An operating ring 3 having a gear portion 3a is fitted into the outer diameter portion of the inner cylinder portion 1b, and a helicoid screw 1c is provided at the outer diameter portion of the inner cylinder portion 1b. Further, the focus barrel 4 holds the focus lens 5, and a helicoid screw 4a is coupled to a helicoid screw 1c of the fixed barrel 1. Further, one end surface side of the focus tube 4 has a gear portion 4b.

Also, 8 mainly seen in Fig. 2 is a connecting gear, 9 is a shaft,
10 is a pulley, 11 is a gear, 12 is a connecting gear, 13 is a shaft, 14 is a pulley, 15 is a gear, 16 is a shaft, 17 is a gear,
18 is a belt.

That is, the connecting gear 8. The shaft 9 and the pulley 10 are connected to the front plate 6
The connecting gear 8 meshes with the threaded portion 3a of the operating ring 3, and a pin 9a protrudes from the shaft 9. A gear 11 having a convex portion 11a is rotatably supported on the shaft 9. On the other hand, the connecting gear 12, the shaft 13, the pulley 14
The gear 15 is also rotatably integrated with the front base plate 6 and the rear base plate 7, and the connecting gear 12 meshes with the gear portion 4b of the focus cylinder 4. Furthermore, gear 1
5 is connected to the gear 11 via a gear 17 which is rotatable with respect to a shaft 16 fixed to the rear base plate 7, and the pulley 14 is connected to the belt 1.
8 and a pulley 10, respectively.

At this time, the reduction ratio of the belt transmission system, which is the second transmission system including the pulley 10, belt 18, and pulley 14, is the gear 11.
, gear 17, and gear 15, which is a first transmission system.

In the lens barrel focusing mechanism explained in FIGS. 1 to 3, focusing is performed by rotating the operating ring 3 to move the focus barrel 4 holding the focus lens 5 in the optical axis direction. It is done by

That is, when the operating ring 3 is rotated, the connecting gear 8 rotates, and the pin 9a and the pulley 10 rotate integrally with the connecting gear 8 via the shaft 9.

Next, the rotation is transmitted to the pulley 14 via the belt 18, and the connecting gear 12 rotates via @13, which is integrated with the pulley 14.

Further, the rotation of the connecting gear 12 is transmitted to the focus barrel 4 via the gear portion 4b, and the focus barrel 4 is connected to the fixed barrel 1 by a helicoid screw 4a that rotates eight times in the optical axis direction.

At the same time, the gear 11 meshes with the gear 15 rotating integrally with the shaft 13, and rotates in the same direction as the shaft 9 and pin 9a via the gear 17, but as described above, the belt transmission system Since the reduction ratio of the gear transmission system is larger than that of the gear transmission system, the pin 9a eventually comes into contact with one end surface of the gear protrusion 11a, and thereafter the rotation of the pin 9a is caused by the gear protrusion 11a1.
When the power is transmitted in the order of gear 11, gear 17, and gear 15, and the shaft 13, pulley 14, and connecting gear 12, which are integrally configured with gear 15, cause the belt transmission system to slip, the power is transmitted by the belt transmission system. , and moves the focus barrel 4 in the optical axis direction.

At this time, because of the relationship (reduction ratio of the belt transmission system)>(reduction ratio of the gear transmission system), the amount of movement of the focus tube 4 with respect to the rotation angle of the operating ring 3 is the same as when the power is transmitted by the gear transmission system. This is larger than when power is transmitted by a belt transmission system, and rough adjustment can be performed.

Further, the slip of the belt transmission system is released by rotating the operation ring 3 in the opposite direction, and within the range until the pin 9a comes into contact with the other end surface of the gear protrusion 11a,
The focus tube 4 can also be moved in a direction corresponding to the rotational direction of the operating ring 3 via the belt transmission system to perform fine adjustment.

FIG. 4 shows the relationship between the rotation angle of the operating ring 3 and the amount of movement of the focus cylinder 4 due to the above operation.

In FIG. 4, point 0 is the initial position, and point A is the pin 9a.
is in contact with the end surface of the gear convex portion 11a, point B is the operation y
Point C, the position at which reverse rotation of J3 starts, is the position where the pin 9a comes into contact with the other end surface of the gear convex portion 11a due to the reverse rotation of the operating ring 3.

Therefore, the straight lines OA and BC represent the relationship between the rotation angle of the operating ring 3 and the amount of movement of the focus cylinder 4 in the case of power transmission by the belt transmission system, and the straight line AB represents the relationship between the rotation angle of the operating ring 3 and the movement amount of the focus cylinder 4 in the case of power transmission by the gear transmission system. In the example, the line AB
and the slope of straight line BC, that is, the operating ring 3 due to both transmission systems.
Due to the difference in the amount of movement of the focus barrel 4 with respect to the rotation angle, fine adjustment can be made in the range between points B and C.

Furthermore, for rotation angles of the operating ring 3 that exceed the above range, the gear transmission system causes a straight line BD.

The focus barrel 4 is moved according to CD'.

Furthermore, the amount of movement of the focus barrel 4 relative to the rotation angle of the operation ring 3 by each transmission system can be freely set by the reduction ratio of both transmission systems, and the range of rotation angles of the operation ring 3 in which power is transmitted by the belt transmission system. This can also be freely set by adjusting the circumferential angle of the gear convex portion 11a.

[Effects of the Present Invention] As described above, according to the present invention, as a power transmission mechanism for transmitting the rotation of the driving side to the moving mechanism that moves the focus lens in the optical axis direction, Two transmission systems are used: a first transmission system that is connected with a slight amount of play, and a second transmission system that has a slip mechanism, and the reduction ratio of the second transmission system is set to be the same as the first transmission system. Since the reduction ratio is larger than that of the transmission system, there is no need for switching operations for only the rotation of a single power source.
A coarse and fine adjustment effect can be obtained during focusing, and it can also be easily applied to zoom lenses and O/I/focus lenses that use the movement of the optical axis direction of the driving side for zooming, without requiring a complicated structure. It is possible to do so.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is an enlarged front view of the main power transmission part, and FIG. 3 is an enlarged front view of the main power transmission part. FIG. 4 is an enlarged cross-sectional plan view taken along cutting line A-A, and is an explanatory diagram of the operational relationship. DESCRIPTION OF SYMBOLS 1...Fixed image, 3...Operation ring, 4...Focus cylinder, 5...Focus lens, 8...Connection gear, 9...Axis, 9a...Bin,
10... Boo Li, 11... Gear, ll
a...G)゛Convex portion, 12...Connection gear, 14
...Boo Li, 18...11. Figure 2 early, Figure 1 Figure 4 ↑ Tsuyoshi 430 rotation angle

Claims (1)

[Claims] 1 In a lens barrel having a focusing mechanism,
As a power transmission mechanism for transmitting the rotation of the driving side to the movement mechanism for moving the focus lens in the optical axis direction, the first transmission has a connection relationship with a slight play in the rotation direction. and a second transmission system with a slip mechanism interposed therebetween, the second transmission system having a larger reduction ratio than the first transmission system. focusing mechanism.