JPS6313165B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a self-deforming absorption lens, in which the lens itself absorbs changes in shape due to temperature within the lens frame of a lens such as a plastic lens in its own configuration, and the original performance of the lens is affected by temperature changes within the lens frame. We have improved the temperature resistance of lenses with poor temperature resistance such as plastic lenses, and expanded the operating temperature range, making it possible to construct and provide lens systems with strong temperature resistance. The purpose is to get used to it. Conventionally, when a lens, for example, a plastic lens 1, is mounted in a lens frame 2, the back outer peripheral edge 1a of the plastic lens 1 is placed on the lens frame body mounting portion 3 of the lens frame 2, as shown in FIG. 1a. The plastic lens 1 is fitted into the lens frame fitting part 4 while being in contact with each other, and the threaded part 7 threaded on the outer periphery of the presser ring 6 is screwed into the lens frame threaded part 5 threaded on the inner periphery of the lens frame 2. At the same time, screw the retaining ring 6 into the inside of the lens frame 2, and press the contact edge 8 formed on the inner peripheral edge of the retaining ring 6, which contacts the plastic lens 1, with the outer peripheral edge 1b on the front side of the plastic lens 1. It is constructed by fixing a plastic lens 1 within a lens frame 2. Now, when the plastic lens 1 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 1 will be the same as that of the lens frame 2. and is larger than the linear expansion coefficient of the molding material of the presser ring 6,
The clearance of the lens frame fitting portion 4 in the lens frame 2 is reduced. Furthermore, the first group is most affected by this effect.
At point A where the lens and the presser ring contact each other in Figure 1 (see the enlarged view shown in Figure 1B), the clearance is already at zero when the parts are assembled at room temperature. In a high temperature atmosphere, the difference in coefficient of linear expansion of the molding materials of the lens 1 and the presser ring 6 directly affects the surface shape. That is, the contact area A between the lens 1 and the presser ring 6
At this point, the outer peripheral edge 1b on the front side of the lens 1, which the contact edge 8 of the presser ring 6 presses against, is depressed and the presser ring 6
The lens 1 is regulated to a state of zero clearance by the abutting edge 8 . Therefore, as the temperature increases, the plastic lens 1 begins to expand in the radial direction, but the restraint ring 6 restricts the deformation of the plastic lens 1 in the radial direction. Thermal stress occurs inside the lens 1. Then, the thermal stress generated inside the plastic lens 1 concentrates on unregulated deformation in the optical axis direction, causing the plastic lens 1 to deform in the optical axis direction. Considering the cross section in the axial direction including the optical axis of the plastic lens 1, 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 1 is α, then it is approximated as A'B'⌒≒AB⌒・(1+αt). Conversely, when the plastic lens 1 and lens frame 2 assembled together at room temperature are exposed to a low-temperature atmosphere, the linear expansion coefficients of the molded materials of the plastic lens 1, lens frame 2, and presser ring 6 differ as described above. Therefore, as the temperature decreases, the plastic lens 1 contracts more than the lens frame 2 and the presser ring 6, and tends to shrink more than the lens frame 2 and the presser ring 6.
In this case as well, the outer peripheral edge 1b on the front side of the plastic lens 1, which is fixed by pressure contact with the abutment edge 8 of the presser ring 6, is restricted, so that the shrinkage of the plastic lens 1 is prevented as in the case at high temperatures. The plastic lens 1 cannot be contracted more than the contraction of the holding ring 6, and thermal stress is generated inside the plastic lens 1. This thermal stress causes the holding ring 6 of the plastic lens 1 to shrink.
The plastic lens 1 is concentrated in the direction of the optical axis, which is not subject to any regulation, and deforms the plastic lens 1 in the direction of the optical axis. Therefore, the plastic lens 1 shown in FIG.
Considering the axial cross section including the optical axis of the chord AB
Since the length of is restricted by the presser ring 6, contraction is concentrated on the arc AB⌒, and as a result, the radius of curvature becomes larger. 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 low temperature is A'B'⌒, and the coefficient of linear expansion of the molding material of the plastic lens 1 is α, it approximates to A'B'⌒≧AB⌒・(1−αt). Therefore, from the above, Plastic Cleanse 1
When the plastic lens 1 is mounted in a lens frame 2 having a conventional structure using a retaining ring 6, it is obvious that the radius of curvature of the plastic lens 1 changes due to temperature changes, that is, it becomes smaller at high temperatures and becomes larger at low temperatures. In comparison, it can be seen that the focus position shifts significantly and various aberrations worsen. Further, in the conventional lens and lens frame configuration, as shown in FIG. 1e, the lens holding member 10
At least two lenses 12, 13 are fitted into the lens fitting part 11 of the lens fitting part 11, and both lenses 12, 1
By interposing the alignment member 14 between the lenses 1 and 3, the two lenses 1 that are adjacent to each other by their outer peripheral edges can be aligned.
A composite lens constructed to reduce the frictional resistance between lenses 12 and 13 and to prevent misalignment of the lenses between both lenses 12 and 13 was proposed in Japanese Utility Model Application No. 55-138606. ing. However, in the case of this configuration, two lenses 1
The structure in which the lenses 12 and 13 are fixed in the fitting part 11 by the presser ring 15 only reduces the friction between the lenses 12 and 13, and there is no change in the conventional structure. The outer diameter is regulated by the fitting part 11 of the lens holding member 10 or the inner diameter of the holding ring 15, and similarly to the plastic lens 1, it is possible to prevent changes in the radius of curvature of both lenses 12 and 13 due to temperature changes. 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 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 lens holding structures. There was a strong need for the development of appropriate countermeasures. Therefore, the present invention improves the structure of the lens itself to absorb and correct changes in the radius of curvature due to temperature changes of the lens within the fitting part of the lens frame.
The aim is to provide a lens system that can avoid lens focus shifts and aggravation of various aberrations. A self-deformable absorption lens is characterized in that it is constructed by providing a foamed layer or a plurality of plate-like pieces each having a foamed layer. Hereinafter, the self-deforming absorption lens of the present invention will be specifically explained with reference to the illustrated embodiments. Figures 2a and 2b show a first embodiment of the present invention;
0 is a lens body, and this lens body 20 is molded from a plastic material such as acrylic resin. Further, 21 is a foam layer for absorbing lens deformation provided all around the outer periphery of the lens body 20, and this foam layer 21 can be integrally molded on the outer periphery of the lens body 20 after the lens body 20 is molded. By mixing a foaming agent with the same material as the molding material of the lens body 20, for example, acrylic resin, and foaming it, the foam layer 21 can be molded in the molding process for the outer periphery of the lens body 20. When molding the foam layer 21 along the outer periphery of the lens body 20, in order to make the bond between the two more solid, the foam layer 21 is molded along the outer periphery of the lens body 20 in advance. An anchor 22 is integrally provided, and this lens anchor 22
It is preferable to construct the foam layer 21 by molding the foam layer 21 through the foam layer 21, and by molding the foam layer 21 using a mold, foam molding is performed in the same mold. A skin layer 23 can be integrally formed on the surface layer of the foamed layer 21. However, the structures of the lens anchor 22 and the skin layer 23 in the structure of the foam layer 21 are not necessarily essential components in implementing the present invention. Further, the molding material for the lens body 20 is not limited to plastic, and it is of course possible to use glass as well.
It is preferable to select a material having a smaller elastic modulus than that of the molding material, for example, the lens body 20.
When molded with acrylic resin, acrylic resin, ABS resin, or other molding material is used for molding. Now, when the self-deforming absorption lens 24 having the above structure is mounted in the lens frame 25, as shown in FIG.
As shown in FIG. 2, one side surface 21a of the foam layer 21 provided along the outer periphery of the lens body 20 is brought into contact with the lens frame body mounting portion 26 of the lens frame 25, and the lens body 20 is
By fitting the foam layer 21 of
Insert it inside. Thereafter, the presser ring 28 is screwed into the lens frame 25 while screwing its threaded portion 29 to the threaded portion 30 of the lens frame 25, and the side surface 28a of the presser ring 28 is attached to the foam layer 24 of the self-deformable absorption lens 24. The lens 24 is fixed by the holding ring 28 while being brought into contact with the other side surface 21b. Note that the foam layer 21 of the self-deforming absorption lens 24
The clearance between the outer diameter at the fitting part 27 of the lens frame 25 and the inner diameter at the fitting part 27 of the lens frame 25 can be designed and implemented in the same manner as the fitting part of a general glass lens and a lens frame to which it is attached. Under such a configuration, the self-deforming absorption lens 2
4 is deformed due to temperature change, i.e.
As the lens body 20 expands as the temperature rises, even if the clearance between the outer diameter of the foam layer 21 and the inner diameter of the fitting part 27 of the lens frame 25 becomes zero, the radial direction of the lens body 20 Expansion can be absorbed by the outer foam layer 21, and as a result, thermal stress can be prevented from occurring in the lens body 20, and large changes in the lens shape can be avoided. In addition, shrinkage of the lens body 20 in the radial direction due to a decrease in temperature can also be absorbed by the foam layer 21, and a similar effect can be obtained. Furthermore, when the lens body 20 is directly pressed and fixed by the presser ring 28, the lens body 20
However, in the case of the self-deformation absorbing lens 24 of the present invention, the side surface 21b of the foam layer 21 formed along the outer periphery is attached to the retaining ring 28. As a result, stress relaxation between the pressure contact surface 28a of the presser ring 28 and the side surface 21b of the foam layer 21 can be absorbed by the foam layer 21, and the loosening torque of the presser ring 28 can be reduced. Side effects can be obtained that can be prevented. Next, FIGS. 3 a to 3 c show a second embodiment of the self-deformation absorbing lens of the present invention. Instead of the foam layer 21, three plate-like pieces 31 are provided protruding from the outer periphery of the lens body 20. Further, each plate-like piece 31 is provided with a foam layer 32 for absorbing lens deformation, and a skin layer 33 is provided on the surface layer of the foam layer 32, and when forming each plate-like piece 31 made of the foam layer 32, The lens anchor piece 34 is provided to protrude from the outer peripheral surface of the lens body 20 via a lens anchor piece 34 . Furthermore, the structure of the foam layer 21 in the first embodiment is followed in that each plate-like piece 31 is molded integrally with the lens body 20, or that the material for forming each plate-like piece 31 is used. The shape of each plate-like piece 31 in FIG. 3a is a rectangular shape, but it can be shaped into a fan shape as shown in FIG. 3b, or fan-shaped as shown in FIG. 3c. It can be implemented with a shape such as a drum shape, etc. In addition, a plate-shaped piece 3
The number of sheets is not limited to the illustrated embodiment. According to the self-deforming absorption lens 35 having the structure of the second embodiment, the above-mentioned effect of the foam layer 32 is greater than that in the case where the foam layer 21 is provided over the entire outer circumference of the lens body 20. It has characteristics that allow it to exert its effects more effectively. That is, the stress concentration that occurs in the foam layer on the outer periphery due to temperature changes in the lens body 20 is more pronounced in the foam layer 32 of each plate-shaped piece 31 than in the foam layer 21 that covers the entire circumference, and the stress concentration that occurs in the foam layer 32 of each plate-shaped piece 31 is It is easier to obtain the desired effect with the shaped piece 31, and from that point of view it is better than the third type.
A greater effect can be obtained by using the plate-like pieces 31 shown in FIGS. b and c. Regarding the configuration in which the self-deforming absorption lens 35 in the second embodiment shown in the third figure is attached to the lens frame,
Although not specifically illustrated, the structure is similar to that of the first embodiment. FIGS. 4a and 4b show a third embodiment of the self-deforming absorption lens of the present invention, in which along the outer periphery of the foam layer 21 in the structure of the self-deforming absorption lens of the first embodiment,
Annular fitting portion 36 for fitting portion 27 of lens frame 25
It is constructed by providing the following. Further, the fitting portion 36 is provided with a fitting portion anchor 37 so that the fitting portion 36 can be firmly coupled to the foam layer 21.
It is bonded to the foam layer 21 via. The other configurations are the same as those of the first embodiment. Thus, the self-deformable absorption lens 38 of the third embodiment is replaced by the self-deformation absorption lens 24 of the first embodiment.
In the same way, when mounting the lens in the lens frame 25, as shown in FIG. This fitting part 36 can be fixed by abutting one side 36a against the lens frame barrel attaching part 26 and pressing the other side 36b with the inner surface of the presser ring 28 screwed into the threaded part 30 of the lens frame 25. This has the advantage that positioning in the thrust direction is easier than in the case of the self-deforming absorption lenses 24 and 35 of the first and second embodiments. When the material is made of a material having a smaller elastic modulus than the material, the deformation of the lens body 20 in the radial direction can be absorbed by both the foam layer 21 and the fitting portion 36, and the first, 2 Example self-deforming absorption lens 2
The operating temperature range can be expanded compared to the cases of 4 and 35. Furthermore, FIG. 5 shows a fourth embodiment of the self-deformation absorbing lens of the present invention, in which the foam layer 21 for absorbing lens deformation, which was provided all around the outer circumference of the lens body 20 in the third embodiment, is partially removed. It is constructed by providing an annular fitting part 36 on the outer periphery of eight plate-like pieces made of fragmentary foamed layers 21, and the anchor 37 of the fitting part 36 is provided on each of the eight plates. They are connected by anchors 37 protruding from positions corresponding to the shaped pieces. Therefore, in the self-deforming absorbing lens 40 of this embodiment, the lens body 20 and the outer circumferential fitting part The foamed layer 21 as fragmentary plate-like pieces is interposed between the lenses 36 and 36, which corresponds to the technical concept of the self-deformable absorbing lens 35 of the second embodiment as compared to the first embodiment described above. However, it goes without saying that other than that, the same functions and effects as the self-deformable absorption lens 38 of the third embodiment can be obtained. In the illustrated embodiment, the annular fitting portion 36
However, it is also possible to implement this by providing fitting pieces (not shown) only at the ends of the eight plate-like pieces made up of each foam layer 21, and the lens body 20 and the fitting part 8 interposed between 36
The number of plate-like pieces is not limited to the illustrated embodiment, such as three plate-like pieces as in the second embodiment. As is clear from the above description, according to the self-deformation absorption lens of the present invention, the foam layer provided on the outer periphery of the lens body can absorb changes caused by temperature changes in the lens body, especially changes in the radial direction. Therefore, even when the lens is mounted in a conventional lens frame with the same structure, changes in the shape of the lens body due to temperature changes can be minimized. Therefore, the lens performance at room temperature can be maintained without being affected by high or low environmental temperatures, and the temperature range in which plastic lenses, which have particularly poor temperature resistance, can be used can be expanded. In particular, according to the first and second aspects of the present invention, the foam layer provided on the outer periphery of the lens body can be mounted in the lens frame while being pressed by the presser ring, which does not occur in conventional configurations. It is possible to prevent a decrease in the loosening torque of the presser ring due to stress relaxation between the presser ring and the lens, and in contrast to the first invention, the second invention can expect the intended effect in the foam layer to be more pronounced. can. Further, according to the third and fourth aspects of the present invention, by providing the fitting portion on the outer periphery of the foam layer provided on the outer periphery of the lens body, it is possible to ensure the accuracy of the outer diameter dimension of the lens. By selecting the molding material of the fitting portion, the desired action and effect of the foam layer can be promoted, and there is an advantage that the intended action and effect of the foam layer can be accurately obtained. The following table shows the effect of preventing the shape change (change in radius of curvature) of the self-deforming absorption lens according to the present invention due to temperature change. The table shows measured values for a conventional lens, and the table shows measured values for a self-deforming absorbing lens according to the first embodiment of the present invention.The lens body of the self-deforming absorbing lens is made of acrylic resin, and The foam layer is made of ABS resin.

【table】

【table】

【table】 [Brief explanation of the drawing]

Fig. 1a is a side sectional view showing a conventional lens holding device, Fig. 1b is a partially enlarged sectional view of Fig. 1a,
Figures c and d are explanatory diagrams showing changes in the shape of the lens in Figure 1a, Figure 1e is a side sectional view showing a conventional example different from Figure 1a, and Figure 2a is the first lens according to the present invention. FIG. 2b is a plan view showing the embodiment, with some parts omitted;
3 is a side sectional view showing the self-deforming absorption lens shown in FIG. 2a mounted in a lens frame, FIG. Diagram a
FIG. 4A is a partial plan view showing an embodiment of a plate-like piece having a different shape from that of the plate-like piece in FIG.
A plan view showing the embodiment, with some parts omitted, and the fourth
FIG. 4B is a sectional side view showing the self-deforming absorption lens shown in FIG. 4A installed in a lens frame, and FIG. 5 is a plan view showing a fourth embodiment of the present invention. 1...Plastic lens, 2...Mirror frame, 3...
... Lens frame body attachment part, 4... Lens frame fitting part,
5... Lens frame screw part, 6, 28... Holding ring, 7, 2
9, 30... Threaded part, 8... Contact edge, 10... Lens holding part, 11... Lens fitting part, 12, 13
... Lens, 14 ... Alignment member, 15 ... Holding ring, 20 ... Lens body, 21, 32 ... Foam layer, 22 ... Lens anchor, 23, 33 ... Skin layer, 24, 35, 38 , 40... Self-deformation absorbing lens, 25... Lens frame, 26... Lens barrel attachment part, 27... Fitting part, 31... Plate piece, 34...
... Lens anchor piece, 36 ... Fitting part, 37 ...
Mating part anchor.

Claims (1)

[Scope of Claims] 1. A lens anchor protruding from all or part of the outer periphery of the lens body, a foam layer for absorbing lens deformation provided via the lens anchor, and a foam layer provided on the lens frame, a fitting part having an L-shaped cross section and fitting with the foam layer at the top and side surfaces of the L-shape; and a fitting part that presses and fixes the foam layer to the fitting part of the lens frame from the side opposite to the side surfaces. A lens frame characterized by comprising: a holding member that holds the lens; 2. Claim 1, characterized in that a plurality of plate-like pieces made of the foam layer are formed by protruding from the outer periphery of the lens body with spaces between each plate-like piece. lens frame. 3. The lens frame according to claim 1 or 2, characterized in that the lens frame is constructed by providing a skin layer on the surface layer of the foam layer. 4. The lens frame according to claim 1 or 2, wherein the foam layer is formed integrally with the lens anchor. 5. A lens anchor protruding from all or part of the outer periphery of the lens body, a foam layer for absorbing lens deformation that is integrated via this lens anchor, and a foam layer that is provided on the lens frame and has an L-shaped cross section. a fitted part provided along the outside of the foam layer and fitted to the top and side surfaces of the fitting part having an L-shaped cross section; A lens barrel comprising: a pressing member that presses and fixes the fitting portion of the frame from the opposite side of the side surface. 6. The lens frame according to claim 5, wherein the foam layer is provided via a fitting part anchor that protrudes from the inner periphery of the fitted part. 7. The lens frame according to claim 6, characterized in that the lens frame is constructed by providing a skin layer on the surface layer of the foam layer. 8. The lens barrel according to claim 5 or 6, wherein the foam layer is integrally formed on the outer periphery of the lens body and the inner periphery of the fitting portion.