JPS6313166B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lens holding device for holding a lens in a lens frame, and in particular, a lens holding device for holding a lens in a lens frame so that a plastic lens with low temperature resistance does not change its shape even when the temperature changes. The objective is to maintain lens performance by fixing the lens and provide a lens system with strong temperature resistance, that is, to expand the operating temperature range of plastic lenses and other lenses that do not have temperature resistance.

Conventionally, when a lens, for example, a plastic lens 7, is to be mounted in a lens frame 2, the back outer peripheral edge 7a of the plastic lens 7 is placed on the lens frame body mounting portion 4 of the lens frame 2, as shown in FIG. 1a. The plastic lens 7 is fitted into the lens frame fitting part 5 while being in contact with each other, and the threaded part 6 threaded on the outer periphery of the presser ring 1 is screwed into the lens frame threaded part 3 threaded on the inner periphery of the lens frame 2. While doing so, screw the presser ring 1 into the inside of the lens frame 2, and press the contact edge 1a formed on the inner peripheral edge of the presser ring 1, which contacts the plastic lens 7, with the outer peripheral edge 7b on the front side of the plastic lens 7. plastic cleanse 7
is constructed by fixing it within the lens frame 2.

Now, when the plastic lens 7 having such a configuration is assembled to the lens frame 2 at room temperature and then exposed to a high temperature atmosphere, the coefficient of linear expansion of the molding material of the plastic lens 7 will be 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 ring 1, the clearance of the lens frame fitting portion 5 in the lens frame 2 becomes small.

Furthermore, the first group is most affected by this effect.
Contact part 8 between lens 7 and presser ring 1 in Figure a
(Refer to the enlarged view shown in Fig. 1b), the clearance in this part is already zero when it is assembled at room temperature, and the forming of the lens 7 and the presser ring 1 in the high temperature atmosphere The difference in linear expansion coefficient of the materials directly affects the surface shape.

That is, the contact portion 8 of the lens 7 and the presser ring 1
In this case, the outer peripheral edge 7b on the front side of the lens 7, which the contact edge 1a of the presser ring 1 presses against, is depressed, and the lens 7 is regulated to a state of zero clearance by the contact edge 1a of the presser ring 1. .

Therefore, as the temperature increases, the plastic lens 7 begins to expand in the radial direction, but the restraint ring 1 restricts the deformation of the plastic lens 7 in the radial direction. Thermal stress is generated inside the lens 7.

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

Considering the cross section in the axial direction including the optical axis of the plastic lens 7, since the length of the chord AB in FIG. radius becomes smaller.

Now, the length of the arc at room temperature is AB⌒, which is t°C than room temperature.
If the length of the arc at high temperature is A′B′⌒ and the coefficient of linear expansion of the plastic lens 7 is α, then it is approximated as A′B′⌒≒AB・(1+αt).

Conversely, when the plastic lens 7 and lens frame 2 assembled together at room temperature are exposed to a low-temperature atmosphere, the linear expansion coefficients of the plastic lens 7, the lens frame 2, and the holding ring 1 are different, as described above. Therefore, as the temperature decreases, the plastic lens 7 contracts more than the lens frame 2 and the presser ring 1, and tends to shrink more than the lens frame 2 and the presser ring 1.
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 with the abutting edge 1a of the presser ring 1, is restricted, so that the shrinkage of the plastic lens 7 is prevented as in the case at high temperatures. Presser ring 1
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 presser ring 1, causing the plastic lens 7 to shrink. 7 in the optical axis direction.

Therefore, the plastic lens 7 shown in FIG.
Considering the axial cross section including the optical axis of the chord AB
Since the length of is regulated by the presser ring 1, contraction is concentrated on the arc AB⌒, and as a result, the radius of curvature becomes large.

Now, the length of the arc at room temperature is AB⌒, the length of the arc at t℃ lower than room temperature is A′B′⌒, plastic lens 7
Letting α be the linear expansion coefficient of the molding material, it is approximated as A′B′⌒≒AB⌒・(1+αt).

Therefore, from the above, Plastic Cleanse 7
When the plastic lens 7 is mounted in the conventional lens frame 2 by the presser ring 1, the radius of curvature of the plastic lens 7 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 focal 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. 1e, the lens holding member 23
At least two lenses 2 are installed in the lens fitting part 26 of
1 and 22 and both lenses 21 and 22
By interposing the centering member 24 between them, the two lenses 2 that are adjacent to each other by their outer peripheral edges can be
A composite lens constructed to reduce the frictional resistance between lenses 1 and 22 and to prevent lens misalignment between both lenses 21 and 22 was proposed in Japanese Utility Model Application Publication No. 55-138606. ing.

However, in the case of this configuration, two lenses 2
The structure in which the lenses 21 and 22 are fixed in the fitting part 26 by the presser ring 25 only reduces the friction between the lenses 21 and 22, and there is no change in the conventional structure. The outer diameter is regulated by the fitting part 26 of the lens holding member 23 or the inner diameter of the holding ring 25, and similarly to the plastic lens 7, changes in the radius of curvature due to temperature changes of both lenses 21 and 22 can be prevented. First, it is impossible to avoid a shift in focus position and worsening of aberrations due to temperature changes.

Therefore, there is a need for a lens holding structure that prevents changes in the radius of curvature that occur due to 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. There was a strong need for the development of appropriate countermeasures.

Therefore, the present invention proposes a lens holding device that solves the drawbacks of the conventional lens holding device described above and can meet the above-mentioned demands. An example will be explained in detail.

FIG. 2 shows a first embodiment of the present invention.
0 is a lens frame, 31 is a lens body attachment part provided inside this lens frame 30, and 32 is a lens fitting part, and this lens fitting part 32 abuts the outer peripheral back surface 50a on the lens body attachment part 31. Plastic lens to store 5
An inner diameter portion 32a having a larger diameter than the outer diameter of 0 and this inner diameter portion 3
A fitting portion 34 for a disk sleeve 33 for absorbing deformation having a larger diameter than 2a is provided. Further, this fitting portion 34 has a body attachment portion 3 of the disk sleeve 33.
4a is provided.

Reference numeral 35 indicates a threaded portion into which a retaining ring 36 provided inside the lens frame 30 is screwed, and 37 indicates a deformation absorbing frame, with deformation absorbing arms 39 protruding perpendicularly to the inner circumferential direction of the annular main body 38 of the disk sleeve 33. Three radial deformation beams 41 are protruded in a direction parallel to the optical axis and three thrust deformation beams 42 are protruded in a direction orthogonal to the optical axis from the inner periphery of an annular frame 40 having an outer diameter corresponding to the inner diameter of By providing this, it is integrally formed with an elastic member.

Further, the inner diameter between each thrust deformation beam 41 is made to correspond to the outer diameter of the plastic lens 50 so that it can be fitted onto the outer periphery of the plastic lens 50, and each radial deformation beam 41 is formed around the outer periphery of the plastic lens 50. The thrust deformation beam 42 is formed so that it can come into contact with a pressing edge 50b, which is a flat surface provided on the outer peripheral surface of the plastic lens 50, when it is fitted onto the outside.

Therefore, when storing and holding the plastic lens 50 in the lens fitting part 32 of the lens frame 30 having the above structure, first, the plastic lens 50 is
A deformation absorbing frame 37 is fitted around the outer circumference of the deformation absorbing frame 37, and a disk sleeve 33 is attached to the outer circumference of the deformation absorbing frame 37.
After externally fitting, the outer periphery back 5 of the plastic lens 50
0a is applied to the lens barrel attachment part 31, and the disk sleeve 33 that has been fitted around the outer periphery is fitted into the fitting part 34. Furthermore, the presser ring 36 is screwed onto the threaded part 35, and the pressing surface 36a of the disc sleeve 33 is fitted into the fitting part 34. plastic cleanse 50
By pressing the frame body 40 of the deformation absorbing frame 37 fitted around the outer periphery, the plastic lens 50 housed in the lens frame 30 is moved between the inner periphery of the lens frame 30 and the deformation absorbing frame 3
7 and disk sleeve 33 are interposed therebetween.

When the plastic lens 50 fixed as described above is left in a high temperature state, it starts to expand, but the changes in the thrust direction and radial direction are due to the elastic deformation of the thrust deformation beam 42 and the radial deformation beam 41 of the deformation absorbing frame 37, respectively. It can be absorbed.

Further, the expansion of the deformation absorbing frame 37 can be absorbed by the deformation absorbing arms 39 of the disk sleeve 33 fitted around the outer periphery of the frame 37.

In particular, the change in the radial direction of the plastic lens 50 is caused by the radial deformation beam 33 of the deformation absorbing frame 37.
If the deformation cannot be absorbed completely within this elastic deformation, the deformation absorption arm 39 of the disk sleeve 33 supplements the deformation absorption, and the absorption action of both can completely absorb the deformation.

Therefore, by changing the elastic modulus of the molding materials of the deformation absorbing frame 37 and the disk sleeve 33, the effect of absorbing changes in the radial direction of the plastic lens 50 can be further improved.

Conversely, if the plastic lens 50 is left in a low temperature state, it will start to shrink, but when assembling it at room temperature, the thrust of the deformation absorbing frame 37 and the protruding direction of the radial deformation beams 42, 41 should be set in the low temperature direction. By forming the plastic lens 50 in a deformed manner, the plastic lens 50 can be held without wobbling due to the return elasticity of the deformed beams 41 and 42 as the plastic lens 50 contracts.

Therefore, according to the lens holding device of this embodiment, it is possible to prevent the plastic lens 50 held in the lens frame 30 from changing its shape (particularly, changing its shape r) due to temperature changes.

The shape and protruding state of the deformation absorbing arm 39 of the disk sleeve 33 as the deformation absorbing sleeve,
In addition, the shape, arrangement, etc. of the thrust deformation beam 41 and the radial deformation beam 41 of the deformation absorbing frame 37 are not limited to the illustrated embodiment, and it is possible to achieve the intended effect of both, and to cause the lens to shift or tilt. This can be implemented with a configuration that does not allow

FIG. 3 shows a second embodiment, which is different from the first embodiment in that the structure of the disk sleeve 33 is integrated with the structure of the lens fitting part 32 of the lens frame 30 in the first embodiment. are the same.

That is, the deformation absorbing beam 4 corresponding to the deformation absorbing arm 39 of the disk sleeve 33 in the first embodiment
3 protrudes from the inner periphery of the lens fitting part 32 of the lens frame 31, and the deformation absorbing beam 43
As shown in FIG. 3b, three deformation absorbing beams 43 are protruded from each other at equal intervals in the inner circumferential direction of the lens fitting portion 32, and the inner diameter of each deformation absorbing beam 43 corresponds to the outer diameter of the deformation absorbing frame 37. At the same time, a notch 44 is provided at a portion of the lens body mounting portion 31 facing each deformation absorbing beam 43.

It should be noted that the number and shape of the deformation absorbing beams 43 and the body mounting portions 30 are not limited to these, as long as they can hold the lens 50, absorb deformation in the radial direction of the deformation absorbing frame, and position the deformation absorbing frame.

Then, the plastic lens 50 is dropped into the lens barrel 30 with its outer circumferential back 50 a against the lens body attachment part 31 , and the deformation absorbing frame 37 fitted around the outer circumference is placed between each deformation absorbing beam 43 of the lens frame 30 . By fitting and holding the deformation absorbing frame 37 and fixing the deformation absorbing frame 37 with the presser ring 36 screwed onto the threaded part 35, the plastic lens is inserted into the lens frame 30 via each deformation absorbing beam 43 and the deformation absorbing frame 37. Hold 50.

Even in the case of the plastic lens 50 in the lens holding device having such a configuration, the deformation absorbing beam 4
3 and the deformation absorbing frame 37, the same effects as in the first embodiment can be achieved, and the plastic lens 50 can be held while being prevented from changing in shape due to temperature changes.

Next, FIG. 4 shows a third embodiment.

A self-deformation absorbing lens 51 having a lens peripheral deformation absorbing portion 45 thinner than the lens minimum thickness on the outer periphery of the lens 50 and an engaging edge 46 that engages with the radial deformation beam 41 of the deformation absorbing frame 37 is placed inside the lens frame 30. A deformation absorbing frame 37 fitted around the outer periphery of the holding ring 36 is interposed between the holding ring 36 and the rest of the structure is the same as that of the first embodiment.

Further, the outer diameter of the engaging edge 46 provided in the lens peripheral deformation absorbing portion 45 of the self-deformation absorbing lens 51 is made to correspond to the inner diameter of each radially deformable beam 41 of the deformation absorbing frame 37, so that it fits between each radially deformable beam 41. The deformation absorbing portion 45 is formed with a thickness thinner than the minimum thickness of the plastic lens 50.

Further, the inner diameter of the lens fitting portion 32 is formed to correspond to the outer diameter of the deformation absorbing frame 37.

In the lens holding device of this embodiment, the lens periphery deformation absorbing portion 45 provided in the self-deformation absorbing lens 51 provides the same effect as the deformation absorbing arm 39 of the disk sleeve 33 in the first embodiment, and also prevents deformation. Absorption frame 37 Radial deformation beam 41
You can get a synergistic effect with.

It should be noted that the shape of the lens peripheral deformation absorbing portion 45 may be any shape as long as it can absorb the dimensional change in the radial direction of the plastic lens 50 from the relationship between the shape of the deformation absorbing frame 37 and the molding material, and the shape of the lens peripheral deformation absorbing portion 45 may be any shape as long as it can absorb the dimensional change in the radial direction of the plastic lens 50. It is not limited to the examples.

FIG. 5 shows a fourth embodiment, which differs in structure from the self-deforming absorption lens 51 in the third embodiment, but is otherwise the same.

That is, the self-deformable absorption lens 51 is constructed by protruding a lens anchor 52 on the outer periphery of the plastic lens 50 and forming a foam layer 53 on the outer periphery of the plastic lens 50 via the lens anchor 52. After fitting the deformation absorbing frame 37 around the outer periphery of the deformation absorbing lens 51,
The back surface 53a of the foam layer 53 is pressed against the lens body mounting part 31 and dropped, and the deformation absorbing frame 37 on the outer periphery is fitted into the lens fitting part 32, and the pressing surface of the presser ring 36 screwed into the threaded part 35 The plastic lens 50 is held within the lens frame 30 by being pressed and fixed at 36a.

Therefore, the foam layer 5 of the self-deforming absorption lens 51
Due to the elastic deformation effect of No. 3, the dimensional change due to temperature change of the plastic lens 50, which corresponds to the lens peripheral deformation absorbing portion 45 in the third embodiment, is absorbed,
A synergistic effect with the deformation absorbing frame 37 can prevent the shape from changing.

Note that the foam layer 53 can be formed integrally on the outer periphery of the plastic lens 50 by mixing a necessary synthetic resin material with a foaming agent and using a foam molding method. By freely selecting and combining the material properties of the various materials, it is possible to obtain an elastic effect that is not found in other embodiments, and therefore, it is possible to expect a better effect of preventing changes in the shape of the lens.

FIG. 6 shows a fifth embodiment, in which the thrust and radial deformation beams 42, 41 of the deformation absorption frame 37 in other embodiments are formed in the presser ring 36, and the deformation absorption frame 37 is omitted. The structure is such that it is possible to obtain the same effect while doing so.

That is, the presser ring 47 in such an embodiment
is formed by protruding a radial deformation beam 49 and a thrust deformation beam 54 from the inner periphery of a cylindrical main body 48.

The radial deformation beam 49 and the radial deformation beam 54 are arranged at the deformation absorbing frame 37 in FIG. 2b.
(In other words, the screw portion 3 of the lens frame 30 is formed on the outer peripheral surface of the frame body 40 of the deformation absorbing frame 37 in FIG. 2b.
The presser ring 47 of this embodiment can be configured by providing a threaded portion that is screwed into the ring 5). However, each radially deformed beam 54 has a protruding base end 5 as shown in FIG.
4b is curved to have an arcuate cross section, and a pressing portion 54a of the outer peripheral pressing edge 50b of the plastic lens 50 is provided at the tip thereof.

Therefore, the outer circumferential back surface 50a of the lens barrel 30 is brought into contact with the lens mounting portion 31, and the lens fitting portion 32
The self-deforming absorption lens 51 housed in the screw part 3
By fitting the radially deformable beam 49 provided in the presser ring 47 screwed onto the outer periphery of the foam layer 53 to the outer periphery of the foam layer 53, and fixing it while pressing the front side of the foam layer 53 with the thrust deformation beam 54, the inside of the lens frame 30 is fixed. The self-deforming absorption lens 51 can be held via the radial and thrust deforming beams 49 and 54 of the holding ring 47.

In particular, by integrating the configuration of the deformation absorbing frame 37 with the holding ring 47, it is possible to obtain strokes in the thrust direction of the radial and thrust deformation beams 49, 54, realizing a more effective beam shape. can do.

Although the arrangement and shape of the radial and thrust deformation beams 49, 54 in the holding ring 47 are shown as examples of the configuration based on the configuration of the deformation absorbing frame 37 in FIGS. 6 and 2b, the present invention is not limited to these. Plastic Cleanse 5
This can be implemented with a configuration suitable for absorbing zero thrust and radial deformations.

Therefore, the holding device in this embodiment also has the same effect as the other embodiments due to the configuration of the radial and thrust deformation beams 49, 54 of the presser ring 47 and the foam layer 53 of the self-deformation absorbing lens 51. In addition, compared to other embodiments,
In addition to simplifying the configuration by omitting the deformation absorbing frame 37, by integrally providing the radial and thrust deformation beams 49 and 54 on the presser ring, a stroke in the thrust direction can be obtained, and both beams 49 and 54 can be used more effectively. You can expect good effects.

Further, although the embodiment is not specifically shown in the drawings, the self-deforming absorption lens 5 shown in FIG.
1, the self-deformable absorption lens 51 shown in FIG.
A lens holding device that fixes the lens with the holding ring 47 of the embodiment, or a holding ring 47 of the embodiment in place of the deformation absorbing frame 37 and the holding ring 36 of the first and second embodiments shown in FIGS. 2 and 3. Even with a lens holding device to which the present invention is applied, the intended effects of the present invention can be obtained.

As is clear from the above description, according to the lens holding device of the present invention, when the lens housed in the lens frame is fixed by the holding ring, the dimension of the lens changes in the radial direction and/or thrust direction between the lens frame and the lens. By providing a deformation absorbing sleeve that absorbs dimensional changes in the radial direction and interposing the deformation absorbing sleeve between the radial directions, it is possible to hold the lens within the lens frame without looseness and to prevent changes in the shape of the lens due to temperature changes. This can be prevented by the action of both the means and the sleeve, as well as their synergistic action.

As a result, it is possible to expand the operating temperature range of a lens system using a plastic lens.

Furthermore, it is not limited to plastic cleansing,
By applying the lens holding device of the present invention to the conventional lens holding method, which easily deforms due to temperature changes and lens fixing methods, it is possible to hold the lens while maintaining the same performance as when it was used alone, even after the lens is assembled.
The design quality of the lens system can be achieved.

[Brief explanation of the drawing]

1a to 1e show a conventional lens holding device,
Figure 1a is a side sectional view, Figure 1b is an enlarged sectional view of Figure 1a, and Figures 1c and d show changes in the radius of curvature of the lens due to temperature changes in the lens holding device in Figure 1a. FIG. 1e is a side sectional view showing an embodiment different from FIG. 1a, FIGS. 2 to 6 show first to fifth embodiments of the present invention, and FIGS. Figure a,
4 to 6 are longitudinal sectional front views showing the first to fifth embodiments;
FIG. 2b is a perspective view of the deformed absorption frame used in the first embodiment, and FIG. 3b is a sectional view taken along line A--A in FIG. 3a. 30...Mirror frame, 31...Lens barrel attachment part, 32...
... Lens fitting part, 33 ... Disc sleeve, 3
4... Fitting part, 35... Threaded part, 36, 47...
Presser ring, 37... Deformation absorption frame, 38... Main body, 3
9... Deformation absorption arm, 40... Ring body, 41, 49...
... Thrust deformation beam, 42, 54 ... Radial deformation beam, 43 ... Deformation absorption beam, 44 ... Notch, 45
... Lens peripheral deformation absorption part, 46 ... Engagement edge, 4
8...Main body, 50...Plastic cleanser, 51
... Self-deforming absorption lens, 52 ... Lens anchor, 53 ... Foam layer.

Claims (1)

[Scope of Claims] 1. A plurality of thrust deformation beams are provided on an annular frame in a direction parallel to the optical axis and a plurality of radial deformation beams are protruded in a direction perpendicular to the optical axis in an alternating manner. A deformation absorbing frame that holds the surfaces in contact with each other and absorbs dimensional changes in the radial and thrust directions of the lens, and a deformation absorbing frame that is inserted between the lens frame on the outer peripheral side of this deformation absorbing frame and absorbs dimensional changes in the radial direction. A lens holding device comprising: a deformation-absorbing sleeve that absorbs deformation; and a presser ring that presses the other surface of the lens against a fixing member in the lens frame via the deformation-absorbing frame. 2. The lens holding device according to claim 1, wherein the lens frame is provided with a deformation absorbing beam. 3 A plurality of thrust deformation beams are provided on an annular frame in a direction parallel to the optical axis, and a plurality of radial deformation beams are provided in a direction perpendicular to the optical axis, respectively, in an alternating manner, and these deformation beams are used to hold one side of the lens in contact with the surface. , a deformation absorbing frame that absorbs dimensional changes in the radial direction and thrust direction of the lens; a holding ring that presses the lens against the barrel mounting portion of the lens barrel via the deformation absorbing frame; and the other surface of the lens. A lens holding device comprising: a presser ring that presses the deformation absorbing frame against a fixing member in the lens frame through the deformation absorbing frame. 4. The lens holding device according to claim 3, wherein the lens frame is provided with a deformation absorbing beam. 5. A self-deformation absorbing lens having means for absorbing dimensional changes in the radial direction of the lens, and a plurality of thrust deformation beams parallel to the optical axis and radial deformation beams perpendicular to the optical axis arranged alternately in an annular frame body. a deformation absorbing frame that protrudes and is held in contact with one surface of the self-deformation absorbing lens by these deformation beams to absorb dimensional changes in the radial direction and thrust direction of the self-deformation absorbing lens; A lens holding device comprising: a presser ring that presses the other surface of the lens against a fixing member in the lens frame via the deformation absorbing frame. 6. The lens holding device according to claim 5, wherein the self-deformation absorbing lens is provided with a lens peripheral deformation absorbing portion on the outer periphery of the plastic lens, the lens peripheral deformation absorbing portion having an engaging edge with each thrust deformation beam of the deformation absorbing frame. 7. The lens holding device according to claim 5, wherein the self-deforming absorption lens is a plastic lens with a foam layer provided around the outer periphery thereof. 8. A self-deformation absorbing lens having means for absorbing dimensional changes in the radial direction of the lens, and a plurality of thrust deformation beams in a direction parallel to the optical axis and radial deformation beams in a direction perpendicular to the optical axis in an annular frame body, each having a plurality of them. a retainer ring integrally provided with means for absorbing dimensional changes in the radial direction and thrust direction of the self-deforming absorbing lens, which are individually protruded and held in contact with one surface of the self-deforming absorbing lens by these deformable beams; A lens holding device, characterized in that the holding ring presses the other surface of the self-deforming absorption lens against a fixing member in a lens frame. 9. The lens holding device according to claim 8, wherein the self-deformation absorbing lens is provided with a lens peripheral deformation absorbing portion on the outer periphery of the plastic lens, the lens peripheral deformation absorbing portion having an engaging edge with each thrust deformation beam of the deformation absorbing frame. 10. The lens holding device according to claim 8, wherein the self-deforming absorption lens is a plastic lens with a foam layer provided around the outer periphery thereof.