JPS58178306A - Lens holder - Google Patents

Abstract

PURPOSE:To prevent the deformation in the optical axis direction of a plastic lens by the effect of temp. by using elastically deformable beams and supporting the lens on one side therewith. CONSTITUTION:The other side of a plastic lens 36 whose one side is in contact with a retaining ring 33 is supported to a leg part, etc. by means of a thrust beam 37, a radial beam 38, etc. which are provided respectively with grooves 39, 40 and are freely elastically deformable, and the thermal expansion, etc. of the lens 36 by the effect of temp. are absorbed by the beams 37, 38, etc. Therefore, no internal thermal stress is accumulated in the lens 36 when temp. changes and the deformation of the lens 36 in the optical axis direction with a change in temp. is prevented.

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 presser ring.

Conventionally, when a lens, for example, a plastic lens T, is mounted in a lens frame 2, as shown in FIG. Fit the plastic lens 7 into the lens frame fitting part S while making contact with the lens frame, and screw the threaded part 6 threaded on the outer periphery of the presser ring 1 into the lens frame threaded part 3 screwed on the inner periphery of the lens frame 2. Screw the presser foot 111 into the inside of the lens frame 2 while attaching the presser ring 1 to the outer circumferential edge 71 on the front side of the plastic lens 7.
3 and fixing the plastic lens T in the lens frame 2. Now, after assembling the plastic lens T having the above configuration to the lens frame 2 at room temperature, When exposed to a high temperature atmosphere, one of the molding materials of the plastic lens 7
Since the elongation laW# is larger than the coefficient of linear expansion of the molding material of the lens frame 2 and the presser ring 1, the clearance of the lens frame fitting portion 5 in the lens frame 2 becomes small.

Furthermore, the area most noticeably affected by this is the contact area 4B between the lens and the presser ring in Figure 1 (see the enlarged view shown in Figure 1); The clearance is already in a state of zero, and in the high-temperature atmosphere, the difference in coefficient of linear expansion of the molding materials of the lens 7 and the presser ring 1 does not directly affect the surface shape.

That is, when the lens 7 and the presser ring 1 hit each other, the outer peripheral edge 7b on the front side of the lens 7, which is in pressure contact with the contact edge 1& of the presser ring 1, is dented, and the abutment edge 1& of the presser ring 1 causes the lens to 7 will be regulated in the state of clearancezep.

Therefore, as the temperature increases, the plastic lens 7 begins to swell in the radial direction, but the deformation of the plastic lens 7 in the radial direction is restricted by the restraint 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 7 in the axial direction including the optical axis, the length of the chord B in FIG.
Because it is regulated by.

Expansion concentrates on the arm B, and as a result, the radius of curvature becomes smaller.

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

Mu'B'→MuB・(1+αt) Approximate to

Conversely, when the plastic lens 7 and lens frame 2 assembled together at room temperature are exposed to a low-temperature atmosphere, as described above, due to the difference in linear expansion coefficients of the molding materials of the plastic lens 7, lens frame 2, and presser foot 111, As the temperature decreases, the plastic lens 7 shrinks more than the lens frame 2 and the presser ring 1, and the lens frame 2 and the presser ring f! 41, but in this case as well, the outer peripheral edge 7b on the front side of the plastic lens 7, which is fixed by pressure contact of the contact edge 1a of the presser ring 1, is restricted, and as a result, in the case of the above-mentioned high temperature. Similarly, the plastic lens T cannot shrink more than the presser foot fRl, and thermal stress is generated inside the plastic lens 7, and this thermal stress is regulated by the presser foot 1M11 of the plastic lens 7. This results in a deformation of the positive lens 7 in the optical axis direction.

Therefore, considering the axial cross-section including the optical axis of the plastic lens 7 shown in FIG.
As a result, contraction is concentrated in arc B.

The radius of curvature becomes larger.

Now, the length of the arc at room temperature is AB, and the length of the arc at t℃ lower than room temperature is A'! l', and the M expansion coefficient of the molding material of the plastic lens T is α.

Approximate to (1-α t ).

Therefore, from the above, when the plastic lens 7 is mounted in the lens frame 2 having the conventional structure using the presser foot W41,
The radius of 9 curvature of the plastic lens T changes due to temperature changes. That is, it is clear that it is small at high temperatures and becomes large at low temperatures, and it is also clear that the focus position shifts significantly and various aberrations worsen 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 21.22 and interposing the centering member 24 between both lenses 21.22, the distance between the two lenses 21.27 adjacent to each other by their outer peripheral edges is A composite lens constructed to reduce the frictional resistance in the lens 21 and 22 and to prevent lens misalignment between the two lenses 21 and 22 has been proposed as proposed in Japanese Utility Model Application Publication 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 and 22 are fixed in the fitting part 26 by the presser ring 25 is no different from the conventional structure, and the outer diameter of the lens 21 and 22 is fixed to the fitting part 26 of the lens holding member 23 or the presser ring 25. It is restricted by the inner diameter of the ring 25, and as with the plastic lens 7, it is not possible to prevent changes in the radius of curvature of both lenses 21° and 22 due to temperature changes, resulting in shifts in focus position and worsening of aberrations due to temperature changes. is impossible to avoid.

Therefore, a lens holding structure that prevents changes in the radius of curvature caused by temperature changes in the conventional lens mounting structure for the 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.

It is an object of the present invention to overcome the above-mentioned drawbacks and 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 first embodiment of the lens holding device of the present invention, in which a lens holder 1133 is screwed into a lens frame threaded portion 32 provided on the inner surface of a lens frame 31. FIG. A thrust beam 37 is formed radially inward on the lens frame 31 to position the plastic lens 36 between it and the holding ring 33 in the axial direction.

The position of the presser ring 33 is determined by the presser ring body attaching portion 44,
The lens 36 is held by the elasticity of the thrust beam 37.

A radial beam 3B is further formed on the lens frame 31.

The radial inner surface of the radial beam 38 provides radial positioning of the lens 36. As shown in Figure 2, the radial beam 38. The thrust beams 37 are each formed as vII number of protrusions spaced apart from each other, and are constructed such that they do not overlap each other in the axial direction. This eliminates the need for the mold for forming the lens frame 31 to have a complicated shape such as an undercut. Furthermore, it becomes easy to set the rigidity of the radial beam 38° thrust beam 37 to a desired value.

During assembly, the axial position of the plastic lens 36 is determined by the end surface 35 of the presser ring 33 that is in contact with the presser body attachment portion 34.
The radial position of the lens 36 is determined by the radial inner surface of the radial beam 38.
8 and the outer peripheral surface of the lens 36 are brought into contact with a slight elasticity to ensure accurate positioning in the radial direction during assembly.

When the lens frame 31 having the plastic lens 36 reaches a high temperature, the lens 36 expands. In the known example shown in FIG. 1, the lens was deformed because the outer circumferential surface of the lens directly contacted the inner surface of the lens frame. Thermal expansion of the lens 36 is absorbed by the elastic deformation of the radial beam 38, and the radius of curvature of the lens 36 does not change due to the deformation of the lens 36.

The expansion of the lens 36 in the axial direction is absorbed by the elastic deformation of the thrust beam 37. Radial beam 38. Thrust beam 3
When it is necessary to reduce the elasticity of the groove 7, radial grooves 40 and thrust grooves 39 of required dimensions are formed.

When the lens system is brought to a low temperature, the lens 36 contracts, but the radial beam 38 during assembly. The contraction is absorbed by the elasticity of the thrust beam 37, and no wobbling occurs in the lens 36.

Usually, the lens frame 31 is made of a synthetic resin material with high rigidity and low elasticity. Thrust beam 37. If the required elasticity value of the radial beam 38 is compatible with the material properties of the lens frame 31, the beam 37.
The material 38 and the material of the lens frame 31 can be integrally molded using a known double molding method.

FIG. 3 shows a second embodiment of the invention. Each part formed on the lens frame 31 is the same as that in FIG. 2 and is indicated by the same reference numeral.
A detailed explanation will be omitted, but in the case of FIG. 3, a peripheral parallel portion 42 is formed on the plastic lens 41 to increase the surface of contact with the thrust beam 37, thereby ensuring reliable positioning in the axial direction. The thrust beam 37 is slightly elastically deformed during assembly to ensure lens retention.

In the case of FIG. 3, the thrust beam 37 is replaced by a rigid body member shown in FIG. 1 for positioning in the axial direction, and the presser w43
3 may also have a structure in which it does not contact the presser foot body attaching portion 34. Since the width of the flat portion 42 of the lens 41 is small, dimensional changes in the axial direction due to thermal expansion and contraction are very small, and changes in the radius of curvature of the lens 41 or loosening of the attachment can be ignored. Thermal expansion and contraction of the lens 41 in the radial direction is absorbed by the elasticity of the radial beam 38.

4 and 5 show a third embodiment of the lens holding device of the present invention. Similar parts or parts are indicated by the same reference numerals as in the older sister figure 3.

In this embodiment, an inclined beam 45 is used in place of the thrust beam 37 shown in FIGS.
The lens 41 is positioned in the axial direction by making contact with the lens 41. As in the previous embodiment, the inclined beam 45 is elastically deformed during assembly to provide axial holding force. In the case of this embodiment, the elastic deformation dimension is made larger than the upright x lath (m37) in FIGS. 2 and 3, and the lens holding force can be increased. The function of the radial beam 38 is similar to the example shown in FIGS. 2 and 3.

The example in FIG. 4 shows an example in which the radial beam 38 and the inclined beam 45 are formed as the same protrusion, and are formed as the entire circumference or a plurality of required protrusions.

Grooves 47 may also be formed to adjust the elasticity of the inclined beams 45.

FIG. 5 shows that the radial beam 38 and the inclined beam 45 are separately attached to the mirror frame 3.
It is formed as a protrusion that protrudes from the inner surface of 1. In this case, the radial beams 38 and the inclined beams 45 are alternately projected from the inner surface of the lens frame 31 when viewed in the circumferential direction, and are arranged so that they do not overlap when viewed in the axial direction, thereby simplifying the mold.

FIG. 6 shows another embodiment of the lens holding device of the present invention. Similar parts or components are designated by the same reference numerals as in Figure 2.3.

In the example shown in FIG. 6, a lens peripheral taper s52 is provided at the outer peripheral edge of the plastic lens 51.

Inclined radial beam 5 with the same taper as the tapered portion 52
3 to position the plastic lens 510 in the radial direction. As in the previous example, the position of the lens 51 in the axial direction is determined by the thrust beam 3T.

In the example shown in FIG. 6, the inclined radial beam 53 is integrally formed with the thrust beam 3T and is projected from the inner surface of the lens frame 31, but it can be formed as a separate projecting portion as in the previous example. .

The mirror frame with the shape shown in Figure 3 is made of polycarbonate, and the radial beam and thrust beam are made of ABa resin and are integrally formed using a double molding method.

The table below shows the results of an experiment comparing the change in the radius of curvature of the shaped platform when the temperature changes with that of a lens made using a conventional fixing method. The number is the radius of curvature.

Indicates rl'l.

According to the present invention, by forming a radial beam that elastically deforms in the radial direction and a thrust beam that elastically deforms in the axial direction within the lens frame, it is possible to prevent the shape change of the lens body caused by a one-degree change, and the lens It is possible to realize an improvement in the temperature resistance of 9, without impairing the accuracy of positioning in the radial and axial directions during assembly.

Although the present invention was developed for use with plastic lenses with a large coefficient of thermal expansion, it is also useful for accurately holding parts that are easily distorted and deformed when fixed with conventional retaining rings, such as glass lenses with a thin center wall. It is suitable to be used as a holder, as the mounting is elastically held in place.

Accurate positioning is possible without causing deformation.

When assembling at room temperature, radial beam thrust beam,
In particular, by assembling the inclined beams that serve as thrust beams with a predetermined elastic deformation, the positioning in the axial and radial directions becomes accurate and no gaps are required during one assembly.

Furthermore, there is no loosening or rattling during shrinkage at low temperatures.

By using separate materials for the lens frame, radial beam, and thrust beam and integrally molding them using a double molding method, it is possible to set the rigidity of the nine lens frames and the elasticity of each beam to desired values.

If necessary, only the radial beam can be made elastically deformable, and the axial direction can be kept rigid.

[Brief explanation of the drawing]

Figure #11 shows the prior art; Figure 1 is a cross-sectional view of part of the lens frame and lens;
Figure 0 is a diagram showing the change in the radius of curvature when the lens is expanded, Figure 1d is a diagram showing the change in the radius of curvature when the lens is contracted, Figure 1.
is a cross-sectional view of the lens holding device with the centering member inserted, Figure 2a
2 is a partial sectional view of a lens frame according to the first example of the actual rod of the lens holding device of the present invention, FIG. 2 is a perspective view of FIG. 2, and FIGS. It is a partial sectional view showing an example of a bar. 1.25, 33 fist...presser ring 2.23, 31...lens frame 3.32 fist...inner screw 4...body part 5...fitting part 3T...fist thrust beam 38... Suitable radial beams 39, 40.47...Groove 45...Slanted beam 53...Slanted radial beam Patent applicant Olympus Optical Industry Co., Ltd. Figure 1 (0) (b) Diagram 1 (c) (d) Figure 111 (e) Figure 2 (0) (b) Figure 3 2 8 Figure 4 J) 41 Figure 5 Figure 6 1 M. Kazuo Wakasugi, Commissioner of the Patent Office 1. Display of the case 1975 Patent Application No. 62183 2 Title of the invention Lens holding device 3, Person making the amendment Relationship to the case Patent applicant 4, "Detailed Description of the Invention" column 8 of the attorney's specification, Amendment The description ``inner direction'' is corrected to ``radial direction and axial direction.'' (2) The description "ring trunk attachment part 44" on page 10, line 14 of the specification is amended to read "ring trunk attachment part 34." (3) Detail 4 #11 Lines 4-5 “In the mold...
...is no longer necessary. '' has been corrected to ``This will prevent undercuts and other rough shapes.'' (4) The statement on page 12, line 4 of the specification is retroactively amended as follows. "Deformation (change in radius of curvature, etc.) will not occur." (5) The statement "The arrangement of the mold is simple" on page 15, line 3 of the specification is replaced with "placement." and correct it.

Claims (1)

[Scope of Claims] (1) In a lens holding device that stores a lens in a lens frame and fixes it using a presser ring, an elastically deformable beam is formed along the inner circumference of the lens frame, and the lens 1. A lens holding device characterized in that one side of the lens is supported by an elastically deformable beam and the other side is supported by the presser ring. (2) In a lens holding device that stores a lens in a lens frame and fixes it using a presser ring, along the inner periphery of the lens frame,
A radial beam that can be elastically deformed in the radial direction and a thrust beam that can be elastically deformed in the axial direction are formed, one side of the lens is supported by the radial beam and the thrust beam, and the other side is supported by the presser ring. A lens holding device characterized by: (3) In a lens holding device that stores a lens in a lens frame and fixes it using a presser ring, along the inner periphery of the lens frame,
A radial beam that can be elastically deformed in the radial direction and an inclined beam that can be elastically deformed in the thrust direction are formed, one side of the lens is supported by the radial beam and the inclined beam, and the other side is supported by the presser ring. A lens holding device comprising: (4) The lens holding device according to claim 1, 2 or 3, wherein the elastically deformable beam is provided with a groove at its protruding end. (5) The radial beams and the thrust beams or the inclined beams are arranged alternately along the inner peripheral direction of the mirror frame. Lens holding device as described. (6) The radial beam and the thrust beam or the inclined beam are each formed from the same protrusion.
3. The lens holding device according to item 3 or item 3. (7) The mirror frame is made of synthetic resin, and the elastically deformable beam is made of synthetic resin, which is different from the mirror frame, and is integrally molded by a double molding method. Or the lens holding device according to item 3. (81M) The lens holding device according to claim 1, 2, or 3, wherein the lens is a plastic lens. (9) The lens has a flat portion supported by an elastically deformable beam or a retaining ring. The first aspect of the claim comprises:
Lens holding device as described in Section 2 or Section 3.