JPS58178305A - Lens holder - Google Patents

Abstract

PURPOSE:To absorb the change in the shape of a plastic lens with a change in temp. satisfactorily by using a thin walled supporting member which projects from the inside of a lens frame. CONSTITUTION:A plastic lens 37 is supported by a supporting member 33 which forms a thin walled deformation absorbing material projecting from the inside of a lens frame 31 and in this state, the lens is mounted to the frame 31 by means of a barrel part 32 integrated with the frame 31, a retaining ring 35, an internal screw 36, etc. The change in the shape of the plastic lens with a change in temp. is absorbed satisfactorily by such constitution using the thin walled supporting member and the movement in the focal position, the degradation of an aberration, etc. is prevented without change in curvature, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lens holding device, and more particularly to a lens holding device that stores a lens body within a lens frame and fixes the lens body within the lens frame in the radial and axial direction using a retaining ring.

Conventionally, when a lens, for example, a plastic lens 7, is mounted in a lens frame 2, as shown in FIG. The lens 7 is fitted into the lens frame fitting part 5 while making contact with the lens frame fitting part 5, and the screw part screwed onto the outer periphery of the presser ring 1 is screwed onto the lens frame screw part 3 screwed onto the inner periphery of the lens frame 2. 6
Screw the presser gRl into the inside of the lens frame 2 while screwing together the presser gRl, press the contact edge 1& formed on the inner peripheral edge of the presser foot 1111 with the plastic lens 7 to the outer peripheral edge 7b on the front side of the plastic lens 7, It is constructed by fixing the plastic lens 7 within the lens frame 2.

Now, what happens when the plastic lens 7 constructed as described above is assembled to the lens frame 2 at room temperature and then exposed to a high temperature atmosphere.

The elongation of [11] of the molding material of the plastic lens 7 is the same as that of the lens frame 2.
Since the coefficient of linear expansion is larger than that of the molding material of the presser foot W41, the clearance of the lens frame fitting portion 5 in the lens frame 2 becomes small.

Furthermore, the part that is most noticeably affected by this is the contact area 78 between the lens and the presser ring in Figure 1 (see the enlarged view shown in Figure 1), and this area is affected when assembled at room temperature. The clearance has already become zero, and in the high-temperature atmosphere, the difference in linear expansion coefficient of the molding materials of the lens 7 and the presser ring 1 will affect the shape of the straight wall surface.

That is, the contact portion 4e9 of the lens T and the presser foot 1l11
, the outer circumferential edge 7b on the front side of the lens T, which the contact edge 1 & of the presser ring 1 presses against, is depressed, and the abutment edge 1 of the presser ring 1 is depressed.
1, the lens 7 is regulated to a state of clearance zep.

Therefore, as the temperature increases, the plastic lens T begins to expand in the radial direction, but the deformation of the plastic lens 7 in the radial direction is restricted by the restriction by the presser ring 1. thermal stress occurs.

Then, the thermal stress generated inside the plastic lens 7 concentrates on unregulated deformation in the optical axis direction, causing the plastic lens T to deform in the optical axis direction.

Considering the cross section of the plastic lens T in the axial direction including the optical axis, the length of the string B in FIG.

becomes smaller.

Let α be the S expansion coefficient of lens 7.

Approximate to

Conversely, when the plastic lens 7 and lens frame 2 assembled together at room temperature are exposed to a low-temperature atmosphere, the St.
Due to the difference in tensile coefficient, as the temperature decreases, the plastic lens 7 contracts more than the lens frame 2 and the presser ring 1, and tends to contract more than the lens frame 2 and the presser ring 1. In this case, the outer edge 7b of the front side of the plastic lens T which is fixed by pressure contact of the abutment edge 1a of the presser ring 1 is restricted, and as a result, the shrinkage of the plastic lens 7 is prevented by the presser 111 as in the case at high temperature. As a result, thermal stress is generated inside the plastic lens 7, and this thermal stress is concentrated in the optical axis direction of the plastic lens 7, which is not restricted by the holding ring 1, causing the plastic lens to shrink. 7 in the optical axis direction.

Therefore, considering the axial cross-section including the optical axis of the plastic lens 7 shown in Fig. The result is concentrated contractions.

The radius of curvature becomes larger.

Let α be the linear expansion coefficient of the molding material of the lens 7.

He He He y≧mu1・(1−αt) Approximate to

For the reasons mentioned above, when the plastic lens 7 is mounted in the conventional lens frame 2 with the presser ring 1, the radius of curvature of the plastic lens T changes due to temperature changes. That is, it is clear that the aberration becomes small at high temperatures and becomes large at low temperatures, and it is also found that the focus position shifts significantly and each lens aberration worsens compared to at room temperature.

In addition, in the conventional lens and lens frame configuration, as shown in FIG.
By fitting at least two lenses 21.22 into the lens 6 and interposing an alignment member 24 between both lenses 21.22, the two lenses 21.22 are adjacent to each other by their outer peripheral edges. A composite lens constructed to reduce the frictional resistance between the lenses 21 and 22 and to prevent misalignment of the lenses between the lenses 21 and 22 has been proposed as proposed in Jitsukki No. 55-138606.

However, in the case of this configuration, only the friction between the two lenses 21 and 22 is reduced.

The structure in which the lenses 21, 22 are fixed in the fitting part 26 by the presser ring 25 is the same as the conventional structure, and the outer diameter of the lens 21, 22 is fixed by the fitting part 26 of the lens holding member 23 or the presser ring. As with the plastic lens 7, it is impossible to prevent changes in the radius of curvature of the lenses 21 and 22 due to temperature changes, thus avoiding shifts in the focus position and aggravation of aberrations due to temperature changes. It is impossible to do +1.

Therefore, a lens holding structure that prevents changes in the radius of curvature caused by temperature changes in the conventional lens mounting structure for a lens frame and that does not cause focus position deviation or worsening of various aberrations, or other appropriate measures should be taken. The development of this was desperately needed.

SUMMARY OF THE INVENTION An object of the present invention is to overcome the above-mentioned drawbacks and to provide a lens holding device that allows accurate radial positioning during assembly and holds a plastic lens within a lens frame without changing its shape due to temperature changes. , to widen the operating temperature range of plastic lenses with weak temperature resistance.

Embodiments and drawings illustrating the present invention will be described.

FIGS. 2a and 2b show a lens holding device according to a first embodiment of the present invention. 9 A lens barrel member 32 for holding a plastic lens 3T in the axial direction on the inner surface of a lens frame 31 formed of a synthetic resin material. and a lens fitting portion 34 for holding the lens 37 in the radial direction.

A presser ring screw 36 for screwing the presser ring 35 is formed on the inner surface of the lens frame 34.

The plastic lens 37 is fitted with the lens fitting part 34 on the outer periphery and positioned in the radial direction, contacts the lens body part 32 and positioned in the axial direction, and is fixed by screwing the presser ring 35.

According to the present invention, the lens fitting portion 34 is replaced by the thin deformation absorbing portion 3.
It is formed on the inner peripheral surface of No.3.

When the plastic lens X'37 fixed in the lens frame 31 undergoes a temperature change, the thermal stress generated in the plastic lens 37 is absorbed by the elastic deformation of the deformation absorbing section 33.
Prevents changes in the radius of curvature of the plastic lens 3T.

Therefore, there is no need to increase the clearance between the plus lens 37 and the lens fitting part 34, and the lens 3
T is precisely radially positioned.

As shown in the second [), the lens body portion 32 and the deformation absorbing portion 3
3 is divided into a plurality of parts and arranged alternately so that they do not overlap when viewed in the axial direction. In the example shown in FIG. 2, the body portion 32 and the deformation absorbing portion 33 are in contact with each other when viewed in the axial direction, but they may also be spaced apart from each other when viewed in the axial direction. This eliminates the need for a complicated mold when integrally molding the lens frame 31 with the synthetic resin, and it is possible to create a medium mold that can be pulled out in the axial direction. Furthermore, it becomes easy to set the rigidity of the deformation absorbing portion 33 to a required value.

Figures 3 & N6 show a second embodiment of a lens holding device according to the invention.

A lens fitting part 44 is formed on the inner peripheral surface of the deformation absorbing part 43 formed to protrude from the inner periphery of the lens frame 41, and further a lens film attaching part 42 is formed.

That is, the lens film attaching part 42 and the lens fitting part 44 are integrally formed in the deformation absorbing part 43. In these nine examples, the lens film attaching part 4
2 is flexible in the axial direction, the presser foot W445 screwed into the screw 46 is made to contact the lens frame 41 when holding the plastic lens 4γ, and the deformation absorbing portion 43 is slightly bent to allow the lens 47 to move in the axial direction. The positioning should be done accordingly.

Figure 3: change, shaped storage part 43. An example is shown in which the lens fitting part 44 and the lens film attaching part 42 are formed on the entire inner circumferential surface of the lens frame 41, and FIG. Also in the second embodiment, which shows an example in which the plastic lens 4T is formed, the deformation absorbing portion 43 absorbs the thermal stress of the plastic lens 4T through elastic deformation and prevents the lens 47 from being distorted.

It is made of a different synthetic resin material and can be integrated by a known double acid type 1 processing method.

The experimental results for an example in which the lens frame 31 is made of polycarbonate, the deformation absorbing part 33 is made of MuB8 resin, and the thickness of the deformation absorbing part 33 is 0.8 m are compared with the conventional method, and the results are shown in Section 1. It is shown in Table II. All values are average values of 5 cases.

Table 1 Radius of curvature of lens in normal operating temperature range According to the present invention, the lens fitting part is provided with a deformation absorbing part that absorbs radial thermal stress due to thermal expansion of the plastic lens, thereby reducing radial curvature during assembly. The positioning is accurate and the lens is in the radial direction! ◇Therefore, it prevents the focal position from shifting and aberrations from worsening due to temperature changes, and expands the operating temperature range of plastic lenses.

If the lens fitting part and the deformation absorbing part are all internal peripheral surfaces, elastic deformation can be evenly distributed. However, if the deformation absorbing part becomes too thin, it is possible to divide the deformation absorbing part to make the dimensions accurate during normal assembly and to match the characteristics of the synthetic resin material used.

By integrally forming the lens frame and the deformation absorbing section using different synthetic resin materials, the elastic modulus of the deformation absorbing section can be arbitrarily selected, and therefore the setting range of the shape and dimensions of the deformation absorbing section is widened.

[Brief explanation of the drawing]

FIG. 1 shows the prior art, FIG.
Figure 0 is a diagram showing changes in the radius of curvature during lens expansion.
1 is a diagram showing a change in the radius of curvature when the lens contracts, and FIG. 1 is a sectional view of a lens holding device in which a centering member is inserted. FIG. 2a is a partial sectional view of a lens barrel according to the first embodiment of the lens holding device of the present invention, FIG. 2 is a left end view of FIG. 1,
Figure 3a is a partial sectional view of the lens frame according to the second embodiment;
1b is a left end view of FIG. 3a, and FIG. 3 ◎ is a left end view corresponding to FIG. 1.25, 35, 45... Holding ring 2.23.31.41... Lens frame 3.36, 46... Internal screw 4.32.42... Membrane attachment part 5.34, 44 ...Fitting portion 7.21.22.37.47...Plastic lens 24...Alignment member 33.43...Deformation absorbing portion Patent applicant Olympus Optical Industry Co., Ltd. 111I!
1 (CI) (b) To Figure 11!1) Δ (d) Figure 1 (e) Figure 2I3 (b) 3 To Figure 3) (b) Figure 3 (C) 3 Procedural amendment (voluntary) Showa 57? On the 27th, Mr. Kazuo Wakasugi, Commissioner of the Japan Patent Office, 1. Indication of the case: 1982 Patent Application No. 62182 2. Title of the invention: Lens holding device 3. Relationship with the amended person case: Patent applicant 4. Agent name (6942) Patent attorney Takeshi Nara 5, Date of amendment order 6, Number of inventions increased by amendment 7, Subject of amendment (υ U mirror frame 34 on page 9, line 13 of Meiji Tatami) (2) From the description of "J" in the 6th line of page 11 of the specification to the 12th line of the iris of the same page, the description of "Ksu valley" is corrected to "mirror frame 31". Delete up to

Claims (5)

[Claims] (1) A lens holding device for housing a lens in a lens frame and fixing it using a presser ring, characterized in that the lens is supported by a thin support member protruding from the inner periphery of the lens frame. A lens holding device. (2) In a lens holding device that stores a lens in a lens frame and fixes it using a presser ring, there is a leg part that supports the lens in the axial direction provided on the inner periphery of the lens frame, and a leg part that protrudes from the inner periphery. A lens holding device characterized in that it is supported by a thin deformation absorbing portion that is supported in the radial direction. (3) In a lens holding device that stores a lens in a lens frame and fixes it using a holding ring, the lens is supported in the axial direction provided through a thin deformation absorbing portion that protrudes from the inner periphery of the lens frame. What is claimed is: 1. A lens holding device characterized in that the lens holding device is configured by being supported by a leg portion that supports the lens and a fitting portion that supports the lens in a radial direction. (4) The lens holding device according to claim 1, 2, or 3, wherein the deformation absorbing portion is made of a synthetic resin material having a smaller elastic modulus than the lens frame and is formed integrally with the lens frame. (5) The lens holding device according to claim 2 or 3, wherein the deformation absorbing portion is formed as a plurality of protrusions spaced apart from each other on the inner periphery of the lens frame.