JP3206840B2 - Lens eccentricity adjustment method and lens device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a means for adjusting the eccentricity of a lens or a lens group in a lens apparatus such as a zoom lens apparatus to prevent an image from being blurred.

[0002]

2. Description of the Related Art In a conventional zoom lens device and the like,
Due to the eccentricity of the lens caused by component accuracy and assembly accuracy,
It is difficult to maintain the optical performance in an optimum state, and an image may be partially blurred. In particular, with the recent increase in magnification and miniaturization of lens devices, resinization of lens barrels, and the like, it has become increasingly important how to remove eccentricity of lenses.

To solve this problem, it is conceivable to provide a special mechanism for removing the eccentricity of the lens. However, the eccentricity of the lens is not only a mere misalignment but also a lens tilt, so the mechanism for removing both the axial shift and the tilt of the lens becomes sophisticated and complicated, and dust is generated in the lens device during the manufacturing process. There is a risk of contamination or damage to the lens.

Therefore, conventionally, a specific lens or a group of lenses is rotated about an optical axis to adjust its mounting position, thereby deteriorating image quality due to eccentricity of the lens.
One-sided blurring is suppressed.

[0005]

However, the method of adjusting the fixed lens or the fixed lens group by rotating the fixed lens has a certain effect on the tilting of the lens, but has an effect on the axial displacement of the lens. Is not recognized, and one-sided blur remains in the image.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a lens device that can prevent a partial blur of an image.

[0007]

In order to achieve the above object, the present invention provides a lens apparatus in which a lens frame holding a lens or a lens group is fixed in a lens barrel. A lens frame fixing portion having a support surface perpendicular to the optical axis is formed over the entire circumference, and a slit extending radially outward of the lens or the lens group supported by the lens frame is formed in the lens frame. A boss inserted into the slit is provided on the lens barrel, and the lens frame is provided on the lens frame while being in contact with the support surface of the lens frame fixing portion. The boss provided on the lens barrel is inserted into the slit provided, and is fixed by a fixing screw.

In the lens apparatus according to the present invention, when the fixing screw is loosened, the lens frame moves along the support surface of the lens frame fixing portion along the rotation direction about the boss and the slit. It is characterized in that it can be operated in two directions of a straight line extending to adjust the position.

Further, it is preferable that a part of the lens frame is provided with a protruding part for position adjustment protruding outward, and this protruding part is protruded outward from an opening formed in the lens barrel. It is.

[0010]

The eccentricity adjusting method of the present invention is to adjust the eccentricity by adjusting the axial deviation of a lens or a lens group. This will be described theoretically with reference to FIG.

FIG. 1 is a graph showing the resolution characteristics of a certain lens device, in which the vertical axis represents the resolution and the horizontal axis represents the position on the optical axis. In particular, the point 0 on the horizontal axis indicates the position of the focal plane of the lens device, that is, the position where a film is arranged in a solid-state imaging device such as a CCD in an electronic still camera, or in a normal camera. . The curve shown by the solid line is the curve of the resolution at the center of the optical axis, and the curve of the dotted line is the curve of the resolution of the tangential component at a point at the periphery of the screen away from the optical axis.

FIG. 1A shows the resolution characteristic of a lens apparatus having no decentering. From this figure, the image passing through the center of the optical axis is focused on the focal plane, and the image at the periphery of the screen is focused. It can be seen that the focus is on the under side, that is, the so-called front focus state. In addition, in the example of FIG. 1A, the resolution characteristics are sampled at two points around the screen which are point-symmetric with respect to the optical axis. However, in the case of a lens device having no eccentricity, The resolution characteristics completely match, and are drawn as a single curve in the figure.

On the other hand, FIG. 1B shows the resolution characteristics of a lens device in which one lens is tilted. In this case, a reduction in the overall resolution is observed. Further, as can be understood from the dotted line in the figure, there is a deviation in resolution at two points around the screen that are point-symmetric with respect to the optical axis. This shift appears as a difference in focus state at the position of the focal plane, and this appears as a partial blur of the image.

[0014] This one-sided blur phenomenon also occurs due to the axial displacement of the lens. Therefore, when the resolution is deviated at any two points that are point-symmetrical to each other due to the tilt of the lens or the like, the deviation of the resolution is obtained by appropriately moving the optical axis of the lens in a direction perpendicular to the optical axis. And the resolution of the two points can be matched. The present invention utilizes the adjustment of the resolution by the axis shift, and eliminates the one-sided blur.

In the adjustment method by shifting the axis of the lens, the resolution is reduced as a whole, but it is possible to prevent the partial blurring which has the greatest influence on the image performance.

Such a lens eccentricity adjusting method can be effectively implemented in the lens apparatus according to the present invention. That is, in the lens apparatus according to the present invention, the lens or the lens group holding the lens or the lens group is slid on the support surface of the lens frame fixing portion, so that the lens or the lens group is in a direction perpendicular to the optical axis. Can be moved. At this time, the lens frame can be rotated around the boss. Further, the lens frame can be linearly moved along the direction in which the slit extends. Since such movement is possible, the above-described method of adjusting the lens eccentricity by shifting the axis can be performed.

Further, by using the projecting portion of the lens frame projecting from the lens barrel, the position of the lens frame can be adjusted more easily.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings.

FIGS. 2 and 3 are a vertical sectional view and a horizontal sectional view, respectively, taken along an optical axis showing a part of an electronic still camera having a zoom lens device to which the present invention is applied. In FIG. 2, reference numeral 1 denotes a lens barrel for holding a lens, reference numeral 2 denotes a first fixed lens group, reference numeral 3 denotes a lens group for zooming movable along the optical axis P, and reference numeral 4 denotes Reference numeral 5 denotes a second fixed lens group that is movable along the optical axis P and is a lens group for focus adjustment. Reference numeral 6 denotes a guide bar for guiding the lens group 3 for zooming, and reference numeral 7 denotes a guide bar for guiding the lens group 5 for focus adjustment. A beam splitter 8 is disposed behind the zoom lens device, and a part of the incident light is branched into a fixed image pickup device 9 such as a CCD and a finder system (not shown).

In the illustrated zoom lens apparatus, the lens group that can be adjusted for eccentricity is the second fixed lens group 4. Hereinafter, the second fixed lens group 4 will be described in detail.

The second fixed lens group 4 is held by a lens frame 10 as shown in FIG. Lens frame 1
Reference numeral 0 denotes a cylindrical portion 11 which surrounds and coaxially holds the lenses 4a, 4b, 4c constituting the lens group 4, and an outward flange portion 12 integrally formed at one end of the cylindrical portion 11. It is composed of This flange portion 12
Is perpendicular to the optical axis P 'of the lens unit 4.

On the other hand, at a predetermined position of the lens barrel 1, an inward flange portion 13 is formed over the entire inner surface thereof, and this flange portion 13 is used as a lens frame fixing portion. Front surface 14 of this lens frame fixing portion 13
Is a support surface for supporting the lens frame 10, and the support surface 14 extends in a direction perpendicular to the optical axis P. Also, as shown in FIG.
The support surface 14 is provided with a plurality (three in the illustrated embodiment) of screw holes 15 at appropriate intervals in the circumferential direction.

In the flange portion 12 of the lens frame 10, through holes 16 are formed in the same number and at the same intervals as the screw holes 15. Therefore, the rear surface of the flange portion 12 of the lens frame 10 is connected to the support surface 1 of the lens frame fixing portion 13 of the lens barrel 1.
4, each through hole 16 is inserted into the corresponding screw hole 1.
The lens frame 10 is fixed to the lens barrel 1 by arranging the lens frame 10 and fixing screws 17 to the screw holes 15.

As can be understood from FIG. 6, the inner diameter of the through hole 16 of the flange portion 12 is larger than the outer diameter of the shaft of the fixing screw 17 and smaller than the outer diameter of the head of the fixing screw 17. I have. Therefore, when the fixing screw 17 is loosened, the position of the lens frame 10 can be adjusted.

The head of the fixing screw 17 and the lens frame 10
A spring washer 18 is sandwiched between the flange portion 12 of the lens frame 10 and the flange portion 1 of the lens frame 10 even when the fixing screw 17 is loosened.
2 is maintained while being pressed against the support surface 14 of the lens frame fixing portion 13.

A pair of projecting portions 19 and 20 are integrally formed at the edge of the flange portion 12 of the lens frame 10. These protruding portions 19 and 20 are provided on the flange portion 12.
Extend from the center point in the radially opposite direction. A through hole 21 is formed in each of the projecting portions 19 and 20, and a guide bar 6 for guiding the zoom lens group 3 is passed through the through hole 21. Note that one end of the guide bar 6 is embedded in the lens frame fixing portion 13 of the lens barrel 1. The inner diameter of the through-hole 21 is adjusted so that the position adjustment of the lens frame 10 when the fixing screw 17 is loosened is not hindered.
It is sufficiently larger than the outer diameter of.

Further, the one protruding portion 19 is formed with a slit 22 extending radially outward from the guide bar through hole 21. Lens frame fixing portion 13 of lens barrel 1
A boss 23 protrudes from the support surface 14 at a position adjacent to one side of the guide bar 6. When the lens frame 10 is fixed, the tip of the boss 23 is
Inserted into 2. In the illustrated embodiment, the width of the slit 22 is substantially the same as the outer diameter of the boss 23.

A small hole 24 into which a hook pin 51 of a position adjusting device 50 to be described later is inserted is formed at the tip of the other protruding portion 20. This protruding part 20
Is exposed to the outside through an opening 25 formed in the side wall of the lens barrel 1.

In the above configuration, the lens frame 1
0 is accurately positioned with respect to the lens frame fixing portion 13 of the lens barrel 1 and the fixing screw 17 is tightened, so that the optical axis P of the zoom lens apparatus and the optical axis P of the fixed lens group 4 in the lens frame 10 are fixed. The lens frame 10 is fixed in a state where the 'is located.

However, if the fixed lens group 4 is decentered due to an error in the assembly accuracy or component accuracy and the image is partially blurred, the adjustment is performed as follows according to the present invention.

First, an electronic still camera incorporating a zoom lens device to be adjusted is fixed to an adjustment stand (not shown), and an image is fixed on a fixed image element 9 to observe an image photographed by the zoom lens device. A monitor (not shown) is connected via a processing circuit.

Thereafter, the fixing screw 17 is slightly loosened to release the fixing of the lens frame 10. At this time, the flange portion 12 of the lens frame 10 is pressed against the support surface 14 of the lens frame fixing portion 13 of the lens barrel 1 by a spring washer 18 so as to be perpendicular to the optical axis P of the zoom lens device. Only can be moved. The range of movement of the lens frame 10 is within a range determined by the gap between the shaft of the fixing screw 17 and the through hole 16.

Next, the hook pin 51 of the position adjusting device 50 is inserted into the small hole 24 of the projecting portion 20 of the lens frame 10 projecting from the opening 25 of the lens barrel 1. This position adjustment device is fixed to the same adjustment table to which the electronic still camera is fixed, and its hook pin can be driven in a direction perpendicular to the optical axis of the zoom lens device. The drive mechanism of the position adjusting device 50 in the illustrated embodiment is a normal manual XY stage, and a detailed description thereof is omitted here.

When the hook pin 51 is moved by turning the knob of the position adjusting device 50, the lens frame 10 connected to the hook pin 50 is moved with the movement, and the lens frame fixing portion 13 is moved.
The position is changed by sliding along the support surface 14. Specifically, the lens frame 10 operates in two directions: a rotation direction about the boss 23 (direction B in FIG. 6) and a direction in which the slit 22 extends (direction C in FIG. 6).

At the time of this position adjustment, the operator turns the knob of the position adjustment device 50 so as to obtain the best image while watching the image output on the monitor. When the cause of the eccentricity of the fixed lens group 4 is only the axis deviation, the eccentricity can be completely removed by adjusting the position of the lens frame 10, and the image becomes the best. In addition, when the eccentricity is caused by the lens falling, as described above,
By moving the lens frame 10 to shift the optical axis P 'of the fixed lens group 4, it is possible to eliminate the partial blur of the image.

After the above-described position adjustment has been performed and the image condition displayed on the monitor has been optimized, the hook pin 51
Is removed from the protruding portion 20 of the lens frame 10 and the fixing screw 17 is removed.
To fix the lens frame 10 to the lens frame fixing portion 13.

The above embodiment is an example in which the present invention is applied to a zoom lens device, but the present invention can be applied to other lens devices.

[0038]

As described above, according to the present invention, the image is blurred by a simple means of moving the optical axis of the decentered lens or lens group in the direction perpendicular to the optical axis of the lens device. Can be eliminated, and the image performance can be remarkably improved.

[Brief description of the drawings]

FIGS. 1A and 1B are diagrams for theoretically explaining a lens eccentricity adjusting method according to the present invention, in which FIG. 1A is a graph showing resolution characteristics of a lens device without eccentricity, and FIG. It is a graph which shows a characteristic.

FIG. 2 is a vertical sectional view along an optical axis showing a zoom lens device according to the present invention in an electronic still camera.

FIG. 3 is a horizontal sectional view of the zoom lens device of FIG. 2;

FIG. 4 is a front view of a lens frame.

FIG. 5 is a cross-sectional view taken along line AA of FIG. 2, showing the lens frame removed;

FIG. 6 is a cross-sectional view taken along line AA of FIG. 2, showing a state where a lens frame is attached.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Lens barrel, 4 ... 2nd fixed lens group, 10 ... Lens frame, 11 ... Cylindrical part, 12 ... Flange part, 13 ...
Lens frame fixing part, 14: support surface, 15: screw hole, 16
... through-hole, 17 ... fixing screw, 18 ... spring washer, 1
9, 20 ... projecting part, 22 ... slit, 23 ... boss, 2
4 ... Small hole, 25 ... Opening, 50 ... Position adjusting device, 51 ...
Hook pin.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-165315 (JP, A) JP-A-55-18610 (JP, A) JP-A-62-125308 (JP, A) JP-A-4-165 191714 (JP, A) Actually open sho 59-63316 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02B ^7/ 02-7/10

Claims (2)

(57) [Claims] 1. A lens device in which a lens frame holding a lens or a lens group is fixed in a lens barrel. A lens having a support surface perpendicular to the optical axis over the entire inner circumference of the lens barrel. The frame fixing part is formed and the front
The lens frame includes a lens supported by the lens frame.
Or a slit extending radially outward of the lens group.
And the lens barrel is inserted into the slit.
Bosses are provided, and the lens frame is in contact with the support surface of the lens frame fixing portion , and
The slit provided in the lens frame is installed in the lens barrel.
In a state of eclipse said boss is inserted, is fixed by the fixing screw, the lens frame when loosened the fixing screw along on the support surface of the lens frame fixing portion, said ball
Direction of rotation about the center and the straight line direction of the slit
A lens device which operates in two directions to adjust the position. 2. The lens frame faces the slit of the lens frame.
The position according to claim 1, further comprising a position adjusting protrusion protruding outward at a position, wherein the protrusion protrudes outward from an opening formed in the lens barrel. Lens equipment.