JPH0821939A - Position adjustment device for optical axis of lens - Google Patents

Abstract

(57) [Summary] [Object] To provide an apparatus capable of surely adjusting and fixing a position of a lens in an optical axis direction with a simple mechanism. [Structure] A large number of first engaging portions 15 arranged on the same circumference are formed on a lens supporting member 13, and one first engaging portion 15 is formed on a lens frame 11.
The above-mentioned second engaging portion 16 is formed. When the screw 12 of the lens frame 11 and the screw 14 of the lens support member 13 are screwed to determine the position of the lens L1 in the optical axis direction, the first engaging portion 15
And the second engaging portion are aligned with each other, and a washer 18 having a double engaging portion 19 for engaging with both of them is fitted, and the pressing ring 2 is attached.
Screw in 1 and tighten.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a device for adjusting the position of a lens in the optical axis direction when assembling and adjusting a lens barrel such as a zoom lens.

[0002]

2. Description of the Related Art In the lens barrel, the position adjustment of the lens in the optical axis direction such as ∞ adjustment, zooming adjustment, back adjustment and the like is performed during assembly. The most common adjustment is to screw a lens frame that supports the lens and a lens holding member, and adjust the position in the optical axis direction at the screwed position. According to the screw mechanism, the position in the optical axis direction can be adjusted steplessly by adjusting the screwing amount.

In this lens position adjusting device using the screw mechanism, various locking mechanisms have been conventionally used to fix the lens at the adjusted position.
Examples thereof are shown in FIGS. 11 to 14.

In each of these examples, the lens L is supported by the lens frame 1, and the lens frame 1 is screwed to the lens holding member 2 such as the focus adjusting ring with the screw 3. The lens holding member 2 is joined to the fixing member 8 by a helicoid 9.

In FIG. 11, the inner flange 2 of the holding member 2 is shown.
The lens frame 1 is strongly screwed and fixed by sandwiching the washer 4 for adjusting the gap between the a and the outer flange 1a of the lens frame 1. In FIG. 12, a fixing nut 5 is separately provided and is fastened with a double nut. In FIG. 13, the fixing screw 6 that contacts the lens frame 1 is screwed in from the radial direction of the lens holding member 2.

However, in the mechanism of FIG. 11, when the washer 4 has an inappropriate thickness, the lens frame 1 has to be removed each time to adjust the thickness, which is troublesome. 12
Then, a special jig for tightening the fixing nut 5 is required, and further, when the fixing nut 5 is strongly tightened, the lens may move or the fixing nut 5 may be damaged. In FIG. 13, the screw on the lens frame 1 side may be crushed, or the lens frame 1 and the lens holding member 2 may be deformed.

In FIG. 14, the lens holding frame 1 is replaced with the intermediate holding frame 2.
The intermediate holding frame 2A is screwed and fixed to A and the helicoid 9
The intermediate holding frame 2A is screwed and fixed to the outer peripheral holding frame 2B with the fixing nut 7 by means of the fixing member 8. This adjusting mechanism is used for the intermediate frame 2A for the helicoid 9.
Fine adjustment is difficult because the position in the optical axis direction is adjusted at the screwed position of. Also, there is a risk of loosening due to vibration or the like.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a device capable of surely adjusting and fixing the position of the lens in the optical axis direction with a simple mechanism based on the problems of the conventional position adjusting device of the lens in the optical axis direction. The purpose is to get.

[0009]

SUMMARY OF THE INVENTION It is ideal that the position of the lens in the optical axis direction can be adjusted steplessly, but there is no problem even with stepwise adjustment, and if stepwise adjustment is made, it is simple and reliable. The present invention was made by finding that a fixing mechanism can be obtained.

In the lens optical axis position adjusting device of the present invention, a first engaging portion is formed on the lens supporting member, and a second engaging portion is formed on the lens frame. A plurality of at least one of the two engaging portions are formed on the same circumference, and the other engaging portion is selected to correspond to the plurality of engaging portions, and the first and second engaging portions are It is characterized in that a washer having a double engaging portion which is simultaneously engaged with them in a one-to-one correspondence is provided, and a retaining ring screwed to the lens supporting member is provided to tighten the washer. .

According to this structure, when the distance between the first and second engaging portions is B ° and the pitch of the screw between the lens frame and the lens holding member is Pmm, the step is (B / 360 °) × P. The position of the lens in the optical axis direction can be adjusted, and the lens can be easily and securely fixed to the adjusted position.

If the washer is provided with a spring member, it is possible to prevent the pressing ring from loosening after the washer is tightened with the pressing ring. Further, by providing a plurality of both the first and second engaging portions and shifting one pitch by an integral fraction of the other pitch, the amount of the above adjustment step can be made finer.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to the illustrated embodiments. In this embodiment, the present invention is applied to the optical axis direction position adjusting mechanism of the focus adjusting lens unit L1 located at the forefront of the lens barrel.

In FIGS. 1 and 10, the focus adjustment lens unit L1 is supported by the lens frame 11, and a male screw 12 is engraved on the outer periphery of the flange portion of the lens frame 11. The lens support member 13 is a focus adjustment ring made of a resin molded product,
A female screw 14 that engages with the male screw 12 is engraved on the inside. It is desirable that the male and female screws 12, 14 are single screws and have fine pitch.

As shown in FIG. 2, the lens supporting member 13 has groove-shaped first engaging portions 15 formed at 30 positions at intervals of 12 ° on the same circumference. As shown in FIG. 11 includes hole-like second engaging portions 16 at 120 ° intervals on the same circumference.
Are formed in three places.

Reference numeral 18 in FIG. 1 denotes a washer, and FIG.
Is a state in which the washer 18 is attached to the lens support member 13. Further, FIGS. 5 to 7 are views of the washers alone. As can be seen from these figures, the washer 18 forms a complete annulus as a whole, on which the first,
There are two double engaging portions 19 having a U-shaped cross section, which engage with the second engaging portions 15 and 16 at the same time, at three locations at 120 ° intervals. Further, the washer 18 has spring members 20 formed of leaf springs formed by cutting and raising a part of the washer in the middle of the double engagement portion 19 at three positions at 120 ° intervals and has elasticity in the optical axis direction. are doing. Reference numeral 21 in FIG. 1 denotes a holding ring, which has a male screw engraved on the outer periphery for screwing with the lens support member 13.

After the lens L1 is fixed to the lens frame 11, it is screwed into the screw 14 of the lens support member 13, and the focus position is adjusted while looking at the collimator, for example, to determine the position of the focus adjustment lens unit L1 in the optical axis direction. To do. When the position is determined, the washer 18 is inserted so that the double engagement portion 19 enters the first and second engagement portions. At this time, when the positions of the first engaging portion 15 and the second engaging portion 16 do not match, the lens frame 11 is loosened within a range of less than one pitch of the first engaging portion 15 and then matched, The double engagement part 19 is inserted.

If the washer 18 is attached, the lens frame 11
Cannot rotate with respect to the lens support member 13, and the position of the focus adjustment lens unit L1 in the optical axis direction is fixed. After that, the pressing ring 21 is screwed into the female screw 14 of the lens supporting member 13 and the washer 18 is pressed against the lens frame 11.
Since the washer 18 has the spring member 20, the pressing ring 21 can be prevented from loosening.

In the present invention, the lens is fixed stepwise. In that case, one step is a problem. Assuming that 30 first engaging portions 15 are formed at intervals of 12 ° and the pitch of the screws 14 is 0.75 mm, the first engaging portion 15 is
The pitch moves the lens frame 11 in the optical axis direction by (12 ° / 360 °) × 0.75 = 0.025 mm. That is, this is the step of moving the lens L1 in the optical axis direction. Now, for example, the focal length of the focus adjustment lens unit L1 is -20.6 mm,
If the focal length on the telephoto end side of the entire lens system is 27 mm, (27 / -20.6) ² = 1.7, so the focus position on the film surface is 0.025.
It changes by × 1.7 = 0.043 mm. Therefore, the first
Since the focus position on one film surface by adjusting the engaging portion 15 by one pitch changes by about ± 0.02 mm, it can be adjusted with sufficient accuracy.

FIG. 9 is a diagram showing an embodiment in which the pitch of the second engaging portions 16 is shifted by an integer fraction with respect to the arrangement pitch of the first engaging portions 15. The pitch of the first engaging portion 15 is 12
However, the pitch of the second engaging portion 16 is 1 in FIG.
It is 124 degrees, which is 4 degrees away from 20 degrees. This 4 ° corresponds to 1/3 of 12 ° which is the pitch of the first engaging portion.

That is, the pitch of the second engaging portion is m, n
Can be expressed as an integer of 12 ° m ± (12 ° / n), and in this embodiment, m = 10 and n = 3. If the position on the optical axis of the focus adjustment lens unit L1 is fixed at the position shown in FIG. 9, the first engaging portion 15-1 and the second engaging portion 16-1 are as large as 8 °. It is off, but 15-
The difference between 2 and 16-2 is 4 °, which is small, and 15-3
And 16-3 are coincident with each other and the double engagement portion 20 of the washer 18 is
Can be inserted. The double engagement portion 19 of the washer 18 was formed at three places on the circumference in the embodiment of FIG. 6, but the washer used in the embodiment of FIG.
Only at one place.

As described above, when the phases of the first engaging portion and the second engaging portion are made different, the adjustment pitch can be made finer. In the above embodiment, both the first and second engaging portions are exemplified as the concave portions of the holes or the grooves, but either one or both of them may be formed as the protrusions. Further, various modifications are possible, such as increasing the number of second engaging portions formed on the lens frame and setting the first engaging portions formed on the lens supporting member to about 1 to 3 places.

[0023]

As described above, according to the present invention, the lens frame is screwed into the lens holding member to adjust the position of the lens in the optical axis direction, and then the first and second engaging portions. By fitting the double-engagement portion of the washer together, the lens can be easily and surely fixed in the optical axis direction.
Then, once fixed, it will not be displaced due to vibration or the like.

By providing the washer with a spring member, it is possible to prevent the pressing ring from loosening. Furthermore, by shifting the pitch of the first and second engaging portions by an integer fraction, it is possible to adjust the position of the lens in the optical axis direction at a finer pitch.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a lens optical axis direction position adjusting device according to the present invention.

FIG. 2 is a diagram showing a first engagement portion and a second engagement portion viewed from II in FIG.

FIG. 3 is a front view showing a main part of a lens frame.

FIG. 4 is a front view showing a state in which a double engaging portion of a washer is locked to the first engaging portion and the second engaging portion shown in FIG.

FIG. 5 is a side view of an essential part showing a double engagement part of the washer.

FIG. 6 is a front view of a washer.

FIG. 7 is a side view of an essential part showing a spring member portion of a washer.

FIG. 8 is a front view showing a state in which a lens frame is screwed onto a lens support member and a washer is fitted.

FIG. 9 is a view showing another embodiment of the present invention and is a front view showing a state where a lens frame is screwed onto a lens supporting member.

FIG. 10 is an exploded perspective view of the embodiment of FIG.

FIG. 11 is a vertical cross-sectional view showing an example of using a washer for spacing adjustment in a conventional lens optical axis position adjusting device.

FIG. 12 is a vertical cross-sectional view showing an example of a double nut system in a conventional lens optical axis direction position adjusting device.

FIG. 13 is a longitudinal sectional view showing an example of using a fixing screw in a conventional lens optical axis position adjusting device.

FIG. 14 is a vertical cross-sectional view showing an example of a conventional lens optical axis direction position adjusting device using an intermediate holding frame and a fixing screw.

[Explanation of symbols]

 11 Lens Frame 13 Lens Support Member 15 First Engagement Part 16 Second Engagement Part 18 Washer 19 Double Engagement Part 20 Spring Member 21 Holding Ring

Claims (3)

[Claims] 1. An optical axis direction position adjusting device for a lens, wherein a lens frame for supporting a lens is screwed into a lens supporting member, and the screwing position adjusts the position of the lens in the optical axis direction. A first engaging portion is formed on the member, a second engaging portion is formed on the lens frame, and at least one of the first engaging portion and the second engaging portion is formed on the same circumference. At the same time, the other engaging portion is selected so as to correspond to the plurality of engaging portions, and when one of the first and second engaging portions has a one-to-one correspondence, this correspondence is made. A washer having a double engaging portion that engages simultaneously with the first and second engaging portions is provided, and further, a pressing ring that is screwed to the lens supporting member for tightening the washer in the optical axis direction is provided. A device for adjusting the position of a lens in the optical axis direction. 2. The optical axis position adjusting device for a lens according to claim 1, wherein the washer includes a spring member that is elastically displaced in the optical axis direction. 3. A plurality of the first engaging portions and the second engaging portions are both provided, and the arrangement pitch of one differs from the arrangement pitch of the other by an integer fraction. The optical axis direction position adjusting device for the lens according to claim 1.