JPH04130309A - Driving device of optical system - Google Patents

Abstract

PURPOSE:To decrease the restrictions on lens movement in optical design and to realize an excellent zoom lens barrel by providing a cam on a feed rod with a lead screw so as to deal with the zoom lens movement of all types. CONSTITUTION:A feed rod 1 turns and a moving ring 3 is moved in an optical axis direction by the lead screw part 1a formed on the feed rod 1 if a gear is formed on the side face of a manual operating member not shown in Fig. or actuator, for example, cam member 9, and the cam member 9 is moved by meshing this gear with the driving gear of a motor. The moving ring 2 is merely fitted to the outside diameter of the feed rod 1 and moves in the optical axis direction in synchronization along the shape of the cam surface 9 of the cam member 9 regardless of the lead. The lead screw part 1a has a specified lead. Then, the moving ring 3 moves in proportion to the rotating quantity of the feed rod 1 but the moving ring 2 makes the desired movement which is not restricted by the rotating quantity of the feed rod 1 and deals with the zoom lens movement.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a lens barrel that moves two or more groups of lenses in conjunction with each other in a photographing system such as a video camera, SV left camera-eye reflex camera, etc. .

[Prior Art] A device for interlocking two or more lens groups using lead screws has already been proposed in Japanese Patent Application No. 72932/1999.

FIG. 2 shows an apparatus according to one embodiment of the above application.

In the figure, reference numeral 101 denotes a feed rod 10 having V-shaped spiral grooves 101a and 101b for moving the lens group.
2.103 is a movable ring that holds each lens group.

Reference numeral 104 denotes a guide rod that suppresses eccentricity of the lens group with respect to the optical axis.

105 is a steel ball. 106 is a leaf spring.

With this configuration, the steel ball 105 is forced into the grooves 101a and 101b by the leaf spring 106, so that
When the feed rod 101 is rotated by the driving force of a motor (not shown), the lens group moves in the optical axis direction according to the pitch of the V-grooves 101a and 1olb and the rotational speed of the feed rod 101.

Then, one side rotates clockwise (V groove 1
01a), by cutting a spiral counterclockwise (V groove 101b) on the opposite side, the two lens groups can be moved in opposite directions in conjunction with the rotation of the feed rod.

[Problems to be Solved by the Invention] However, in the above example, since a spiral groove is cut in the feed rod, each lens group moves in one direction depending on the rotating direction of the feed rod. Therefore, it is not suitable for reciprocating the lens group in the optical axis direction in the same rotational direction.

On the other hand, in order to achieve high magnification and compactness of the zoom lens, this reciprocating movement may be necessary, and the configuration shown in FIG. 2 imposes restrictions on the movement locus of the zoom lens.

Further, when the movement locus of at least one lens group among the plurality of groups of the zoom lens is made to be non-linear, the spiral groove of the feed rod must have a plurality of leads. Currently, it is difficult to manufacture a feed rod with multiple leads, resulting in an expensive feed rod.

An object of the present invention is to provide an inexpensive and compact lens group moving mechanism.

[Means for Solving the Problems] The present invention provides a cam member having a non-linear lift for moving another lens group on a feed screw rod for moving one lens group. This makes it possible to link types.

[Example] FIG. 1 shows a first embodiment of the invention.

In the same figure, l is a feed rod, and the trapezoidal groove lead screw part 1a
And it has a normal cylindrical portion 1b.

For convenience, only one groove is shown and the others are omitted.

2.3 is a moving ring holding each lens group, L, 4
is a guide rod that fits into the bearing at the end of the movable ring in order to suppress the eccentricity of the lens groups 2 and 3 with respect to the optical axis. Reference numeral 5 denotes a steel ball, which is biased against the lead screw portion 1a by a plate spring 6 joined to the movable ring 3. 7 and 8 are fixing members forming part of the lens barrel for fixing the feed rod 1 and the guide rod 4; Reference numeral 9 denotes a cylindrical cam member fixed to the cylindrical portion 1b of the feed rod 1, the cam surface 9a has a convex or concave non-linear lift along the circumference, and is in contact with the cam follower 2a of the movable ring 2. . IO is a coil spring press-fitted between movable rings 2 and 3, and is a spring member that eliminates looseness with the feed rod 1.

A steel ball 11 is biased against one end surface of the feed rod 1 by a coil spring 12 to absorb wobbling in the optical axis direction.

Next, in the above configuration, when the cam member 9 is moved by a manual operation member or an actuator (not shown), for example, a gear is formed on the side surface of the cam member 9 and meshed with a drive gear of a motor, the feed rod 1 rotates. The movable ring 3 is moved in the optical axis direction by a lead screw portion 1a formed on the feed rod 1. At this time, the movable ring 2 is only fitted with the outer diameter of the feed rod 1, and moves synchronously in the optical axis direction along the shape of the cam surface 9 of the cam member 9, which is related to the lead.

Here, the lead screw portion 1a has a constant lead.

Therefore, the movable ring 3 moves in proportion to the amount of rotation of the feed rod 1, but the movable ring 2 makes a desired movement that is not restricted by the amount of rotation of the feed rod 1 due to the cam shape of the cam member 9.

If the feed screw rod shown in FIG. 2 is used as part of the feed rod 1 shown in FIG. 1, it is possible to configure a zoom lens drive mechanism having two monotonous movement loci and one non-linear movement locus. .

In addition, if two cam members and a spring member are applied to the feed rod l shown in Fig. 1, two
It is also possible to drive a zoom lens with a curved locus of .

The cam 9 on the upper side is fixed to the feed rod l as a separate member, but it can be integrally formed by molding or gui-casting.

Furthermore, if the movable ring 3 does not move in proportion to the amount of rotation of the feed rod 1, the lead screw 1a and the steel balls 5 and plate springs 6 for biasing the lead screw may be eliminated, and the movable ring 2 and the surrounding surface A configuration like the cam 9 may be used.

Further, the pitch of the lead screw may be changed.

This device can be applied not only to photographic zoom lenses but also to finder zoom lens mechanisms. Also, in addition to variable magnification,
It can also be used for floating during focusing.

[Usage of the Invention] As explained above, by providing the cam on the feed rod with a lead screw, it is possible to cope with all types of zoom lens movement. Therefore, in terms of optical design, restrictions on lens movement can be reduced, and it is possible to realize a zoom lens barrel that is cheaper than a normal cam ring system using a feed rod and does not have multiple leads.

Also, by using a cam, the lens can be moved back and forth, making it possible to achieve higher magnification and a more compact zoom lens.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a zoom lens barrel embodying the present invention. FIG. 2 is a sectional view of the embodiment of the earlier application. ■ = feed rod, la: lead screw part, 2 and 3 = moving ring, 4
: guide rod, 5 and 11 = steel ball, 6: plate spring, 7 and 8: fixed member, 9: cam member, 10 and 12 = spring.

Claims (2)

[Claims] (1) In a device for synchronously moving multiple optical elements in the optical axis direction, a feed threaded rod for moving a predetermined optical element according to an optically determined movement locus is connected to another 1. A drive device for an optical system, characterized in that a member having a non-linear cam for moving an optical element according to an optically determined movement locus is provided so as to rotate integrally with the member. (2) In a device for synchronously moving a plurality of optical elements in the optical axis direction, a drive rod is rotatably driven so that the cam lift changes in the optical axis direction to change the circumferential cam for moving the optical elements. An optical system driving device characterized by being provided with.