JPH02195313A - Driving mechanism for optical system of zoom camera - Google Patents

Abstract

PURPOSE:To give a margin the rotation stop position of a cam plate on a wide-angle end and to prevent a shaft from deforming, breaking, etc., caused by an external force by forming a nonfitting part in the cam groove of the cam plate, enabling the front and rear edges to abut on a lens barrel, and performing different operations by the one cam plate. CONSTITUTION:The nonfitting part is formed at part of the cam groove 4, the front and rear edges 4b and 4c in the direction of the optical axis are enabled to abut on the projection part 1a of the lens barrel 1, and the operations is performed differently between a state wherein the projection part 1a of the lens barrel 1 abuts on the front edge 4b and a state wherein the projection part 1a abuts on the rear edge 4c. The front edge 4b of the nonfitting part of the cam groove 4 is made concentric about the center of rotation and the rear edge 4c is formed in a cam shape connecting with the fitting part; and the lens barrel 1 is energized elastically toward the front edge 4b and the lens barrel abuts on the front edge 4b in a normal state and is positioned at a constant position within the specific rotation range of the cam plate 3. Then when the external force is applied to the lens barrel 1, the lens barrel abuts on the rear edge 4c to rotate the cam plate 3, and the lens barrel 1, cam plate 3, and other proper parts are made to abut, thereby receiving the external force. Consequently, the rotary shaft is prevented from deforming or breaking.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a drive mechanism for an optical system in a zoom camera.

(Prior Art) As a drive mechanism for a zoom lens, a cam ring system is widely used, in which a ring that rotates around the optical axis is provided with cam grooves corresponding to the lift of each lens group.

On the other hand, in the case of a lens with a relatively small zoom ratio, a rotary cam system has been proposed in which a cam groove is formed in a flat plate and the flat plate is rotated around an axis perpendicular to the optical axis to drive the zoom.

(Problem to be Solved by the Invention) In the case of zoom drive using a rotating flat plate cam system, in order to keep the focal length of the lens constant within a predetermined rotation angle range of the rotating flat plate, the cam shape must be relative to the center of rotation. It is on the center of the circle. In this case, when an external force pushing the lens barrel is applied from outside, the force is transmitted from the lens barrel to the cam plate as a centripetal force,
Since no force is generated in the rotational direction of the cam, all of the external force is received by the rotating shaft, eliminating the problem of deformation or damage to the shaft.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to provide a drive mechanism for an optical system that does not cause deformation or damage to the rotating shaft of the cam plate even when an external force is applied to the lens barrel from the front.

(Means for Solving the Problems) According to the present invention, a non-fitting portion is provided in a part of the cam groove, and the front and rear edges of the non-fitting portion in the optical axis direction respectively contact the protrusion of the lens barrel. By making this possible, it becomes possible to arrange the protrusion of the lens barrel at different positions depending on whether it abuts the front edge or the rear edge, thereby making it possible to perform different effects.

The front edge of the non-fitting part of the cam groove is made concentric with the center of rotation, and the rear edge is made into a cam shape continuous from the fitting part, so that the lens barrel is elastically biased in the direction of the front edge. Under normal conditions, the lens barrel contacts the front edge and is placed at a fixed position within the predetermined rotation range of the cam plate, and when an external force is applied to the lens barrel, it contacts the rear edge and rotates the cam plate. It can be rotated and external force can be applied by hitting it against other suitable parts such as the lens barrel or cam plate, thereby preventing deformation or damage to the rotating shaft.

(Function) In the shooting condition shown in FIG. 1, in which the zoom lens shown in FIG. 4 is between the telephoto end and the wide-angle end, the positions of the lens group and 's2 lens group are determined by the cam grooves 4a and 5a, respectively. , arranged as a lens system with a predetermined focal length. When the 'st lens barrel 1 is pushed by an external force in this state, the external force is transmitted from the lens barrel to the cam plate, and the rotational force component rotates the cam plate clockwise, pushing the lens barrel down ◆ .

When you want to position the zoom lens at the telephoto end, rotate the cam plate counterclockwise and the lens barrel protrusion will hit the end of the cam groove, or another appropriate part of the lens barrel will hit the stopper on the camera body. Can be positioned accurately.

On the other hand, when it is desired to position the zoom lens at the wide-angle end, the cam plate is rotated as shown in FIG. It is stopped at a position where the front edge 4b of the cam groove 5 contacts the wide-angle end 5b of the cam groove 5. At this time, since both the front edge 4b and the wide-angle end 5b are concentric with the rotation center of the cam plate, even if there is some error in the rotation angle of the cam plate within this range, the front lens group and the rear Since the group lenses are arranged at the same position, there is a margin in the stopping accuracy of the cam plate at the wide-angle end, and it is possible to accurately arrange the cam plate at the wide-angle end without requiring strict precision. If the lens barrel is pushed by an external force when the lens is at the wide-angle end,
The lens barrel moves downward against the spring 6, extends from the front edge 4b of the cam groove, and comes into contact with the rear Iti4c. If you continue to press it further, the cam plate will rotate clockwise and the lens barrel will be pushed down. When the cam plate 3 is rotated clockwise when the lens is at the wide-angle end, the first group lens barrel 1 is pushed by the collapsible portion 4d of the cam groove and sinks, and the second lens barrel 2 is at the wide-angle end position. The biasing spring does not move from the protrusion 2 of the second lens barrel 2.
The cam plate 3 rotates clockwise while being bent by being pushed by a. The protrusion 2a relatively passes through the wide-angle end 5b of the cam groove 5 as the cam plate rotates. Rear edge 4C of non-mating part
is continuous from the fitting part 4a, and even when the lens barrel is pushed down by an external force from the telephoto end, the cam plate can continue to rotate smoothly.

If the lens barrel continues to be pushed, the cam plate or an appropriate part of the lens barrel will hit the stopper on the main body and stop, allowing the external force to be applied at a location where there is no risk of deformation or damage.

〔Example) The present invention will be described in detail with reference to FIGS. 1 to 4.

In the figure, 1 is the first lens barrel holding the first group lens of the zoom lens, 2 is the second lens barrel holding the second group lens, and both lens barrels l and 2 constitute a zoom lens. Numerals la and 2a are protrusions of the respective lens barrels 1 and 2, which abut the cam grooves of the cam plate 3 to arrange the respective lens barrels at predetermined positions. The cam plate 3 is rotatably supported by a shaft 9 fixed to the main body, and is rotationally driven by a drive mechanism (not shown) to perform zooming. 4 is the protrusion 1a of the first lens barrel
4a is a fitting portion that regulates the position of the lens from the telephoto end to the wide-angle end of the lens group.

4b is the front edge of the non-fitting part and forms a concentric circle with respect to the center of rotation, so even if the cam plate rotates within this range, the position of the first group lens is on the wide-angle side! It is constant at the 4 ends. Reference numeral 4c is the rear edge of the non-fitting portion and when the lens barrel is pushed by an external force, it comes into contact with the lens barrel protrusion and is pushed to rotate the cam plate clockwise. 4d is a collapsible cam surface, and when the cam plate further rotates clockwise from the wide-angle end position, the lens barrel is pushed down and collapsed (Fig. 3).

Reference numeral 4e indicates a rear edge of the collapsible barrel portion, which is a cam surface that smoothly connects the collapsible barrel end position and the rear edge of the non-fitting portion.

5 is a cam groove that the protrusion of the second lens barrel comes into contact with, and 5a
5b is a zoom part that defines the position from the telephoto end to the wide-angle end of the second group, and 5b is a wide-angle end and collapsible part that is concentric with the center of rotation, and the second group lens barrel defines the position from the wide-angle end to the wide-angle end. They are in the same position all the way to the end of the barrel. Reference numeral 6 denotes a biasing spring, one end of which biases the first lens group forward when it moves from the non-fitting portion 4b to the collapsible portion 4d. The other end is biased rearward when the second lens group is at the wide-angle end. 7.8 is a spring stopper provided on the cam plate.

Next, the operation will be explained.

First, in the photographing state of FIG. 1 in which the zoom lens shown in FIG. 4 is between the telephoto end b1 and the wide-angle end, the positions of the first lens group and the second lens group are determined by the cam grooves 4a and 5a, respectively. It is arranged as a lens system with a predetermined focal length. When the second lens barrel 2 is pushed by an external force in this state, the external force is transmitted from the lens barrel to the cam plate, and a component of the rotational force rotates the cam plate clockwise to push down the lens barrel.

When you want to position the zoom lens at the telephoto end, rotate the cam plate counterclockwise so that the lens barrel protrusion hits the end of the cam groove, or another appropriate part of the lens barrel hits the stopper on the camera body. can be positioned accurately.

On the other hand, when it is desired to position the zoom lens at the wide-angle end, the cam plate is rotated as shown in FIG. It is stopped at a position where the front i4b and the wide-angle end 5b of the cam groove 5 abut. At this time, since both the front edge 4b and the wide-angle end 5b are concentric with the rotation center of the cam plate, even if there is some error in the rotation angle of the cam plate within this range, the front lens group and the rear Since the group lenses are arranged at the same position, there is a margin in the stopping accuracy of the cam plate at the wide-angle end, and it is possible to accurately arrange the cam plate at the wide-angle end without requiring strict precision. If the lens barrel is pushed by an external force when the lens is at the wide-angle end,
The lens barrel moves downward against the spring 6, moves away from the front Ja4b of the cam groove, and comes into contact with the rear edge 4c. If you continue to press it further, the cam plate will rotate clockwise and the lens barrel will be pushed down. When the cam plate 3 is rotated clockwise when the lens is at the wide-angle end, the first group lens barrel l moves into the collapsible portion 4d of the cam groove.
The second lens barrel 2 does not move from the wide-angle end position, and the cam plate 3 rotates clockwise while the biasing spring is pushed by the protrusion 2a of the second lens barrel 2 and flexes. do.

The protrusion 2a relatively passes through the wide-angle end 5b of the cam groove 5 as the cam plate rotates.

The rear edge 4c of the non-fitting part is continuous from the fitting part 4a, and the cam plate can continue to rotate smoothly even when the lens barrel is pushed down by an external force from the telephoto end.

If the lens barrel continues to be pushed, the cam plate or a suitable portion of the lens barrel will hit the stopper on the main body and stop, allowing the external force to be applied without fear of deformation or damage.

(Effects of the Invention) As explained above, by providing a non-fitting part in the cam groove of the cam plate and making it possible for the front edge and the rear edge to contact the lens barrel, different effects can be achieved with one cam plate. can be made to do so.

The front edge is concentric with the rotation axis, and the rear edge is shaped like a cam that continues from the fitting part, so during normal operation, the rotation of the cam plate is stopped when accurately positioning the lens at the wide-angle end. Not only can the position be made more flexible, but when the lens barrel is pushed by an external force, the rotational force can be transmitted to the cam plate, preventing deformation and damage to the shaft.

[Brief explanation of the drawing]

1 is a plan view of the drive mechanism of the present invention, FIG. 2 is a plan view of the cam plate when the drive mechanism is in a state corresponding to the wide-angle end of the zoom lens, and FIG. 3 is a plan view of the cam plate when the drive mechanism is in a state corresponding to the wide-angle end of the zoom lens. FIG. 4 is a plan view of the lens in a state corresponding to the retracted end, and is a diagram showing the relationship between the lens barrel and the cam plate. 1... Second lens barrel 2... Second lens barrel 3.
...Cam plate 4...Cam groove 5...Cam groove 4a...Fitting part 4b...Front edge of non-fitting part 6...Biasing spring

Claims (1)

[Claims] 1. A cam plate that is rotatable about an axis perpendicular to the optical axis of the lens, and a protrusion that is inserted into the cam groove of the cam plate and that moves parallel to the optical axis. In a drive mechanism for an optical system in a zoom camera, the cam groove has a portion where the protrusion fits, and a front and rear edge of the cam groove in the optical axis direction abuts the protrusion, respectively. Driving an optical system in a zoom camera, characterized in that the lens barrel is provided with a non-fitting portion that abuts the front edge or the rear edge at different positions in the optical axis direction. mechanism. 2. The front edge of the non-fitting portion forms a concentric circle with respect to the center of rotation of the cam plate, and the rear edge forms a cam shape that continues from the fitting portion, and the lens barrel at the non-fitting portion. 1. A drive mechanism for an optical system in a zoom camera, characterized in that the front edge is elastically biased and comes into contact with the front edge.