JPS6341041B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides at least two cam cylinders provided on one cam cylinder.
The present invention relates to an improvement in a zoom lens barrel that performs zooming by moving at least two movable lens groups in the optical axis direction using various cam grooves.

[Background of the invention]

In the zoom lens barrel as described above, in order to prevent the movable lens group from shaking, it is common to have three cam grooves for each type divided in the circumferential direction in the cam barrel. To ensure smooth movement of the lens group, the rotation angle of the cam barrel is usually set at 60 degrees or more between telephoto and wide-angle. Therefore,
Conventional zoom lens barrels have cam grooves with different torsional directions shifted in the optical axis direction so as not to intersect. As a result, the cam barrel becomes long, and even if the lens design is made more compact, it will not work properly. There is a problem that the length of the torso becomes long.

In order to shorten the cam cylinder, if two cam grooves are provided for each type and divided in the diametrical direction, the movable lens group moved by the cam grooves will be perpendicular to the diametrical direction in which the cam grooves are provided. The lens begins to shake in the direction, and to prevent this, high precision work is required, which requires time and effort to adjust, and furthermore, the lens performance is unstable due to poor durability. There are also lens barrels in which cam grooves with different twisting directions are provided separately on the inner and outer diameter sides of the fixed barrel, but such lens barrels have an increased diameter and a complicated structure.

[Purpose of the invention]

The present invention provides a zoom lens barrel that can be made compact in both diameter and length, provides smooth operability, and has a simple structure.

[Structure of the invention]

The present invention provides at least two different types of cam grooves provided in one cam barrel that rotates around the optical axis, and an optical axis direction guide provided in a fixed barrel that does not rotate around the optical axis. In a zoom lens barrel that performs zooming by moving a movable lens group in the optical axis direction, the different cam grooves are crossed, and the optical axis direction guide is separately provided for the different cam grooves, and the positions are shifted around the optical axis. The zoom lens barrel is characterized in that a plurality of sets of cam grooves are arranged around the optical axis, and the phases of intersection points of the different cam grooves in at least two sets are shifted from each other. achieve.

〔Example〕

The present invention will be explained below using illustrated examples.

FIG. 1 is a sectional view of a zoom lens barrel of the present invention consisting of two movable lens groups, FIG. 2 is a partially exploded view showing a combination of a pair of intersecting cam grooves and optical axis direction guides, etc.; The figure is a perspective view of the cam follower, FIG. 4 is a partially developed view showing another example of the cam follower, and FIG. 5 is a developed view showing a phase shift at the intersection of cam grooves.

In FIG. 1, 1 is a fixed barrel having a mount part 11 that is attached to the camera body, 2 is a zoom ring integrally provided with a cam barrel 21 rotatably fitted to the fixed barrel 1, and 3 is a fixed barrel. 1,
A heicoid ring having a cam follower 31 that engages with a guide groove 1a parallel to the optical axis provided in the fixed barrel 1 and a cam groove 21a provided in the cam barrel 21; 4 is a focus rotatably fitted in the heicoid ring 3; A ring 5 has a key pin 51 that slidably engages with a key groove 4a parallel to the optical axis direction provided in the focus ring 4, and a first lens group holding frame 6 that is screwed into the heicoid ring 3; This is a second lens group holding frame having a cam follower 61 that engages with a guide groove 1b provided in the tube 1 parallel to the optical axis and a cam groove 21b provided in the cam tube 21.

The figure shows a state in which zooming is on the tele (long focus) side, and when the zoom ring 2 is rotated in one direction from this state, the cam barrel 21 also rotates together, and the cam groove 21a is formed into the guide groove of the fixed barrel 1. 1a, the heicoid ring 3 and the first lens group holding frame 5 screwed thereto are moved to the left, and the cam groove 21b is aligned with the fixed barrel 1.
Since the second lens group holding frame 6 is moved to the right along the guide groove 1b, the zooming changes to the wide (short focus) side. Then, zooming from the wide side to the telephoto side is performed by rotating the zoom ring in the opposite direction, and focusing is achieved by rotating the focus ring 4, so that the first lens group holding frame 5 is moved to the heicoid ring 3. It is carried out in a spiral manner. Note that is the first lens group and is the second lens group.

For convenience, FIG. 1 shows only one cam groove 21a and 21b each, and they do not intersect, but in reality, the cam grooves 21a and 21b of the cam cylinder
b intersect as shown in FIG. 2, and the guide grooves 1a and 1b of the fixed cylinder 1 are shifted in position around the optical axis relative to the cam grooves 21a and 21b, respectively, so that there is no interference between the cam followers 31 and 61. has been done,
A plurality of such sets are provided around the optical axis as shown in FIG. Further, in the plurality of sets, the phases of the intersection A positions of the cam grooves 21a and 21b in at least two sets are shifted as shown in FIG.

As shown in FIG. 2, cam grooves 21a and 21b
By making the guide grooves 1a and 1b intersect with each other and shifting the guide grooves 1a and 1b around the optical axis, the length of the cam barrel 21 can be shortened.
A plurality of sets can be easily provided around the optical axis without increasing the diameter of the zoom lens barrel, and the zoom lens barrel can be made smaller.

However, if there is only one combination as shown in FIG. 2, or if there are multiple sets but the intersection positions of the cam grooves 21a and 21b in all the sets are the same, One of the intersecting cam grooves 21a and 21b is a deep groove or a groove penetrating the cam cylinder wall, the other cam groove is a shallow groove, and the cam follower that engages with the deep groove or the through groove is a shallow groove. The cam follower that engages with the shallow groove should have a length in the groove direction that does not enter the deep groove or the through groove at the intersection A. This is necessary in order to prevent problems such as backlash at intersections or problems such as the cam follower entering another cam groove and getting caught, even if a cam follower such as the above is used. FIG. 2 shows this case, in which the cam groove 21a for moving the first lens group whose torsion angle changes is a through groove, and the cam groove 21b for moving the second lens group whose torsion angle is constant is shallow. The cam follower 61, which is a groove and engages with the cam groove 21b, is the guide groove 1b of the fixed cylinder 1.
The cylindrical portion 61a that engages with the shallow cam groove 21b.
For example, the slide piece part 61b has a prismatic slide piece part 61b molded from an elastic material, and the slide piece part 61b has a cam groove 2 that does not enter the cam groove 21a at the intersection of the cam grooves 21a and 21b.
It has a length in the 1b direction. Further, 31 is a cam follower consisting of a pin that engages with the cam groove 21a and the guide groove 1a of the fixed cylinder, and is engaged deeper with the cam groove 21a than with the shallow cam groove 21b. moreover,
FIG. 3 shows the configuration of the above-mentioned cam follower 61, and 61c is a set screw provided integrally with the second lens group holding frame 6 of FIG. Instead of the cam follower 61 shown in FIG. 3, a cam follower as shown in FIG. 4 may also be used. This cam follower 61 consists of a plurality of pins 61d arranged in the direction of the cam groove 21b and implanted in the second lens group holding frame.
The parallel arrangement of the cam grooves 1d prevents the cam groove from entering the other cam groove at the intersection of the cam grooves.

In response to the above, a plurality of combinations as shown in FIG. 2 are arranged around the optical axis, and the phase of the intersection position of the cam grooves 21a and 21b in at least two sets is shifted. In the example, cam cylinder 2
1 is rotated in the direction of the arrow from the illustrated position, and one of the cam followers 31', 31'', 31 or the cam followers 61', 61'', 61 is moved into the cam groove 2.
1a' and 21b', 21a'' and 21b'', 21a and 21
Even if it enters the intersection b, other cam followers are out of the intersection, so even if the cam grooves 21a and 21b are both through grooves and the cam followers 31 and 61 are both cylindrical, the cam follower 3 that is out of the intersection
1 and 61, the first lens group and the second lens group can be moved smoothly without play.

Figure 5 shows three sets of combinations as shown in Figure 2, with the cam grooves of one of the sets arranged at equal positions in the circumferential direction, and the cam grooves of the other set appropriately shifted from the equal positions. However, even if there are only two or more than three combinations, and the phase of the intersection position is changed by shifting both cam grooves from their equal positions, A similar effect can be obtained even if the phases of the intersection positions are shifted between only some of the plurality of sets. The present invention can also be applied to a movable lens group having two or more groups, such as an example in which the movable lens group is guided in the optical axis direction by a guide groove, or a cam groove has a constant torsion angle, and a cam groove has a constant torsion angle, and the torsion angle changes. It goes without saying that the combination of cam grooves is not limited to this example.

〔Effect of the invention〕

According to the present invention, it is possible to obtain a zoom lens barrel that is compact both in the optical axis direction and in the diametrical direction, zooming is performed smoothly without play, has high machining accuracy, does not require the trouble of adjustment, and has excellent durability. When lens performance is stable, excellent effects can be obtained.

In the present invention, the cam cylinder may have a through groove and a shallow cam groove. In that case,
If the cam cylinder is made by stacking and integrating an outer cylinder having a through groove, and an inner cylinder having a through groove corresponding to a shallow groove and a through groove overlapping the through groove of the outer cylinder, the cam cylinder can be easily formed. Productivity is increased and manufacturing costs can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a zoom lens barrel of the present invention consisting of two movable lens groups, FIG. 2 is a partially exploded view showing a combination of a pair of intersecting cam grooves and optical axis direction guides, etc.; The figure is a perspective view of the cam follower, FIG. 4 is a partially developed view showing another example of the cam follower, and FIG. 5 is a developed view showing a phase shift at the intersection of cam grooves. 1... fixed tube, 1a, 1b... guide groove, 2...
Zoom ring, 21...cam tube, 21a, 21b
...Cam groove, 3...Heikoid ring, 31...
Cam follower, 4... Focus ring, 5... First lens group holding frame, 6... Second lens group holding frame,
61...Kam holore.

Claims (1)

[Claims] 1. At least two different types of cam grooves provided on one cam barrel that rotates around the optical axis, and an optical axis direction guide provided on a fixed barrel that does not rotate around the optical axis,
In a zoom lens barrel that performs zooming by moving at least two movable lens groups in the optical axis direction, the different cam grooves intersect, and the optical axis direction guides are separated for the different cam grooves and their positions are shifted around the optical axis. A zoom lens barrel characterized in that a plurality of combinations of cam grooves are arranged around an optical axis, and the phases of intersection points of the different cam grooves in at least two sets are shifted.