JPH0463307A - Device for moving and correcting image point in zoom lens barrel - Google Patents

Abstract

PURPOSE:To continuously and easily execute fine lens position correction by rotating an adjusting ring engaged with a screw part of a fixed ring and finely moving a cam groove to execute image point movement. CONSTITUTION:A cam ring is constituted of a moving ring divided into front and rear parts and adjusted so as to respectively have a cam groove 1a for the 1st moving lens L1 and a cam groove 1a' for the 2nd moving lens L2 and an adjusting ring 8 having a pin engaged with a groove 12 formed on a part of the circumferential direction part of the moving ring. When the ring 8 engaged with the screw part of the fixed ring 2 is rotated, the groove part 12 engaged with the pin 9 is straight moved, the cam groove 1a is finely moved to move an image point. Thereby, the image point movement can be corrected only by rotating the ring 8 from the outside and its fine adjustment can be executed by adjusting the pitch and rotational angle of the screw. In addition, constitution for correction is simple, the device can easily be produced, an adjusting time for correction work can be shortened and the manhour for its production can be reduced.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a lens position correction device for a lens barrel.
More specifically, the present invention relates to a lens position correction device for a zoom lens barrel configured by fitting first and second lens barrels and a lens holding frame.

[Prior Art] Generally, in this type of zoom lens barrel, as schematically shown in FIG. The zooming cam grooves 21 formed on the zoom driving lens barrel 20 and the rectilinear grooves 31 formed on the fixed lens barrel 30 intersect with each other and are fixed to the lens holding frame 40. cam follower pin 50.

Therefore, by rotating the zoom drive lens barrel 20, the cam follower pin 50 moves along the zooming cam groove 21 and is stopped from rotating by the straight groove 31, and the lens holding frame 40 moves accordingly. Then, the desired zooming will be performed.

However, the zoom drive lens barrel 20. Fixed lens barrel 30°, machining errors such as lens holding frame 40, zooming cam groove 21. Since processing errors of the straight groove 31 and cumulative errors when assembling these will inevitably occur, in order to prevent the image point from moving during zooming and deterioration of image quality, the lens holding frame 40 should be adjusted to a predetermined position. It is necessary to make fine adjustments to the position correction so that the position is correct.

For this reason, the cam follower pin 50 is constructed with an eccentric pin, and by rotating this eccentric pin, the relative positions of the zooming cam groove 21, the linear groove 31, and the cam follower pin 50 are adjusted, and then This eccentric pin is tightened and fixed using an identification screw.

However, with such means, there is a risk that the position of the eccentric pin may shift when the fixing screw is tightened and fixed, resulting in incorrect position correction.

In order to solve this problem, a lens position correcting device for a lens barrel is disclosed in Japanese Utility Model Application No. 179529/1983.

That is, when fixing the eccentric pin, a spline shaft is formed on the eccentric pin, and a spline hole that fits into the spline shaft is formed in the lens holding frame, so that when the eccentric pin is tightened and fixed with a fixing screw after position correction. This prevents the eccentric pin from shifting.

In addition, by forming a polygonal shaft and a hole that fits into the shaft instead of a combination of a spline shaft and a spline hole, it prevents the eccentric pin from shifting when tightening and fixing with the fixing screw after position correction. It is also proposed that

[Problems to be Solved by the Invention] However, in such a conventional lens position correction device for a zoom lens barrel, when the eccentric pin is fixed after correcting the lens position, the eccentric pin may be displaced. Although it has the advantage of not being stored away, it has the problem that the amount of drive when correcting the lens position can only be obtained in stages, making it impossible to make continuous fine adjustments.

Therefore, it is an object of the present invention to easily perform very fine lens position correction step by step (continuously), and to prevent the eccentric pin from shifting when fixing the eccentric pin after correcting the lens position. It is an object of the present invention to provide a lens position correction device for a zoom lens barrel.

[Means for Solving Problems] In order to achieve the above-mentioned object, a lens position correction device for a zoom lens barrel according to the present invention includes a movable lens mounted inside a lens barrel having mutually intersecting guide grooves. In an image point movement correction device for a zoom lens barrel incorporating a lens frame holding a cam ring, the cam ring is divided into front and rear parts so as to have a cam groove for a first movable lens and a cam groove for a second movable lens. , a groove is formed in a part of the circumferential direction of the movable ring to be adjusted, and the adjustment ring has a pin that fits into the groove, and by rotating the adjustment ring that fits into the threaded part of the fixed ring. This is an image point movement correction device for a zoom lens barrel, characterized in that the image point is moved by slightly moving a cam groove by linearly moving a groove connected to the pin.

[Example] Hereinafter, the present invention will be described in detail based on the drawings. FIGS. 1 and 2 are a sectional view and a developed view of only the upper half of the structure of an image point movement correction device for a zoom lens barrel according to an embodiment. That is, the zoom lens barrel mainly consists of a cam ring 1. similar to the conventional example shown in FIG. A front group lens holding frame 3 that holds the fixed ring 2 and the movable lens. The rear group lens holding frame 3' is configured to overlap in three layers.

The cam ring 1 provided on the outside has a cam groove 18 for moving the front group moving lens L, as shown in FIG.
A first cam ring l having a gear 1d formed on its outer periphery for engaging and rotating a rotational driving force with a gear (not shown) on the left side, and a second cam having a cam groove 1a' for moving the rear group moving lens L2. Consists of ring 1. A notch 1c is formed at the right end of the first cam ring 1, and a notch 1c is formed at the inner peripheral side of the left end of the second cam ring 1' so that these joints fit and overlap. A notch 1c' having a width equal to the width of the notch 1c is formed. And the first of these. In order to connect the second cam [11', an elongated hole 6 in the optical axis O direction is bored in the center of the notch IC' of the second cam ring 1', and a screw 7 is inserted through this elongated hole 6. The first cam ring 1 is connected by being screwed into a screw hole in the notch IC. Therefore, the distance between the first cam ring 1 and the second cam ring 1' can be adjusted by the length of the elongated hole 6 in the optical axis 0 direction.

The outer periphery of the right end of the second cam ring 1' and the stepped portion 2C of the fixed ring 2
An adjustment ring 8 is provided between them, and a screw 8a is formed on the right inner circumference of the adjustment ring 8. And fixed ring 2
It is threadedly fitted to a threaded portion 2d provided above. Also,
A pin 9 is screwed into this adjustment ring 8, and its tip is provided to engage with a groove 12 formed in the circumferential direction of the second cam ring 1'. Therefore, after loosening the screw 7 of the second cam ring 1' and rotating the adjustment ring 8 for alignment, it becomes possible to adjust the position of the second movable lens L2 relative to the fixed ring 2 in the optical axis O direction.

In a zoo lens barrel formed in this way, it is necessary to correct the image point shift that occurs when assembly is not performed as designed due to processing errors when manufacturing each member or assembly errors such as pin positions during assembly. There is a need to do. As a method of correcting this image point movement, the amount of blur at the longest focal length end (L end), middle point (M), and minimum focal length end (S end) of zooming is calculated, and each This is done by slightly moving either the front group moving lens L or the second moving lens L2 in the optical axis direction to the position averaged as each correction value, depending on the depth of focus of the magnification. At this time, this image point correction can be performed by simply loosening the screw 7 and rotating the adjustment ring 8 relative to the fixed ring 2, for example, to easily finely adjust the rear group lens L2 from the outside in the optical axis direction. Furthermore, fine adjustments can be easily made by adjusting the pitch and rotation angle of the screw.

After fine adjustment, adhesive is inserted into adhesive holes 10 drilled at several locations in the adjustment ring 8, and the adjustment ring 8 is fixed to the fixed ring 2.

Next, a second embodiment will be described based on FIGS. 3 and 4. This example is a method of finely adjusting the correction of the image point movement of the front group lens, and the same members will be described with the same reference numerals. In this example as well, a cam ring is provided on the outermost periphery, a first cam ring l having a cam groove 1a for moving the front group moving lens L1, and a cam groove for moving the rear group moving lens L2. The second cam ring 1' is formed by being divided into a second cam ring 1' having a hole 1a'. Between these, the notch 1c provided on the outer circumference of the first cam ring l and the notch lc' provided on the inner circumference of the second cam ring l' overlap, as in the first embodiment. A screw 7 is inserted into an elongated hole 6 provided in the first cam ring 1' to connect the first cam ring 1' so that it can move in the direction of the optical axis O. The fixed ring 2 having the straight groove 28 provided on the inside has a left front portion as the first one. The second cam Fill, 1' is thicker than the second cam Fill, 1', and a screw 2b is formed on its outer periphery, and the rear end on the right side is fitted into the outer cylinder 11 and fixed thereto. On the inner periphery of this fixed ring 2 is a front group lens L.

The front group lens holding frame 3 holding the rear group lens L2 and the rear group lens holding frame 3' holding the rear group lens L2 are fitted together, and pins 5, 5' are installed perpendicularly to these front and rear group holding frames 3, 3'. are the linear groove 28 of the fixed ring 2 and the cam groove 18 of the first cam ring 1, respectively.
and is provided so as to engage with the cam groove 1a' of the second cam ring 1'. In addition, the screw 2b at the front of the fixed ring 2 has
An adjustment ring 8 having a screw 8a formed on the inner periphery of the left side that engages with the screw 2b is engaged, a pin 9 is screwed into the screw hole of the adjustment ring 8, and its tip is inserted into the first cam ring 1. It fits into a groove 12 provided in the circumferential direction on the outer periphery. Therefore, screw 7
By loosening the adjustment ring 8 and rotating the adjustment ring 8, the first
By moving the cam ring 1 in the direction of the optical axis O, the front lens group L1 can be finely adjusted. At this time, movement of the first cam ring 1 and the second cam ring 1' in the straight direction is restricted by the straight groove 2a formed in the fixed ring 2, and the pitch of the screw 2b of the fixed ring 2 is 0.5. If so, a 90" rotation of the adjustment ring 8 will result in a screw feed of 0.125mm, and by simply adjusting the angle of the adjustment ring 8, the front lens group L can be finely adjusted, and image point movement can be corrected. After the adjustment, the first cam ring 1 and the second cam ring 1' are fixed by screwing in the setscrew 7.Furthermore, the adjustment ring 8 is fixed by forming it at several locations (not shown). This is done by inserting an adhesive into the adhesive hole 10 that has been formed.Furthermore, the adjustment pin 9 also serves to prevent the first cam [1] from being removed.

In this way, the compensation for the image point movement during zooming is:
±0.5 mm is sufficient, and such a configuration allows sufficient fine adjustment.

[Effects of the Invention] As explained above, in the image point movement correction device for a zoom lens barrel of the present invention, correction of image point movement can be performed from outside the lens barrel only by rotating the adjustment ring, and the pitch of the screw can be adjusted by adjusting the pitch of the screw. It can be finely adjusted by adjusting the rotation angle. In addition, the configuration for correction is simple and easy to manufacture, and the adjustment time associated with correction work is shortened, reducing the number of man-hours.In addition, it can quickly increase the amount of fine movement that is difficult to use with conventional eccentric pins. It can also be applied to lenses with high adjustment sensitivity, where lens back etc. change.In addition, the number of parts can be reduced, so parts related to eccentricity of the lens system, such as the double structure of the lens frame, can be used. It is possible to avoid too many.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the upper half of the zoom lens barrel image point movement correction device according to an embodiment of the present invention. FIG. 2 is a developed view of FIG. 1. A cross-sectional view of the upper half of the zoom lens barrel according to the second embodiment of the present invention showing the structure of the image point movement correction device. FIG. 4 is a developed view of FIG. 3. FIG. 5 is a zoom lens barrel. FIG. 2 is a schematic diagram showing a schematic configuration. 1.1'...first cam ring, second cam ring 1a+l
a'... Cam groove 2... Fixed ring 2a... Straight groove 3. 3'... Second lens holding frame, second lens holding frame 5.
5'...Pin 6...Long groove 7...Fixing screw 8...Adjustment ring 9...Pin 11.
・Outer cylinder 12 ・Groove

Claims (1)

[Claims] In an image point movement correction device for a zoom lens barrel, which incorporates a lens holding frame holding a movable lens inside a lens barrel having mutually intersecting guide grooves, a cam ring is connected to a cam groove of a first movable lens and a second movable lens. an adjustment ring which is divided into front and rear parts so as to have a cam groove of the moving lens, a groove is formed in a part of the circumferential direction of the moving ring to be adjusted, and an adjustment ring having a pin that fits into the groove; A zoom lens characterized in that by rotating an adjustment ring that fits into a threaded part of a fixed ring, the groove connected to the pin moves linearly, thereby slightly moving a cam groove and moving the image point. Lens barrel image point movement correction device.