JPS5843407A - Lens holding mechanism - Google Patents

Abstract

PURPOSE:To widen the range for the service temp. of a plastic lens and to prevent the clatters of the lens by interposing a member of a small coefft. of friction in the contact part of the lens and correcting the change in the radius of curvature of the lens owing to a change in temp. CONSTITUTION:A friction washer 5 for a rear part is formed like a plane sheet in the fitting part 5 formed on the inside wall of the body mounting part 4 of a lens barrel. Said washer is formed of a blank material of ''Teflon '' base having 0.08-0.15 coefft. of friction. A plastic lens 7 is fitted into the part 5 and is brought into abutment on a friction washer 9. A friction washer 10 for a front part is inserted into the lens barrel and a retaining ring 1 is screwed to a screw part 3 to fix a screw washer 10 and the lens 7. Since the change in the radius of curvature of the lens 7 owing to a change in temp. is absorbed by the washer 9, 10, the service temp. of the lens 7 is widened, and the clatters of the lens are prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lens holding mechanism for optical equipment such as camera lenses, and more particularly to a lens holding mechanism suitable for use with plastic lenses that have relatively low temperature resistance. be.

Generally, a lens holding mechanism 4 for an optical system such as a camera lens is configured as shown in FIG. To briefly explain each part, reference numeral 4 denotes a lens frame mounting part, and inside the lens frame mounting part 4, an iron base part 5 of the lens is formed. When assembling the parts, first, for example, a convex lens 7 is fitted into the fitting part 5, and then the presser block 1 that is screwed into the threaded part 3 formed on the inner wall of the lens frame 2 is screwed in, thereby adjusting the inner diameter of the engraving presser ring 1. The lens 7 is still held in contact with the peripheral edge of the lens 7.

By the way, in such a lens holding mechanism, for example, when a part assembled at room temperature is placed under a high temperature state or a low temperature state, the difference in linear expansion coefficient of each part will cause the disadvantages described below in I/C. . That is, since the coefficient of linear expansion of the material forming the lens 7 is larger than that of the material forming the lens frame 2 and the presser ring 1, for example, under high temperature conditions, the volumetric expansion of the lens 7 causes the lens frame 2 and the presser ring 1 to expand. This will exceed the same increase in Ring 1.

On the other hand, the lens holding mechanism is originally constructed for the purpose of fixing the lens 7.1. As mentioned above, the clearance is already set to zero under normal temperature conditions, and as a result, under high temperature conditions, it will directly affect the surface shape of the lens. In particular, this influence is most noticeable at the peripheral edge contact portion of the lens 7 with the ridge holding ring 1, and is also noticeable in plastic lenses where the hardness of the wood forming the lens is relatively low. FIG. 2 shows a partially enlarged configuration diagram of the contact portion (single chain circle As in FIG. 1). As is clear from the figure, stress is concentrated at the contact portion 8 between the lens 7 and the presser ring l due to the expansion of the lens 7, resulting in a dent on the surface of the lens 70.

To explain this state in more detail, the lens 7 tends to expand in the radial direction as the temperature increases, but since the peripheral edge of the lens 7 is restricted by the retaining ring 1 as described above, the lens 7 expands in the radial direction. expansion is prevented. Also,
Due to these regulations, thermal stress is generated inside the lens.
As a result, as shown in Fig. 3, the spherical surface is at a position P on the optical axis of the lens at 5, and the spherical surface is at a position P at room temperature. Even though it was in the high temperature condition, it expanded to MP1, and the radius of curvature of the lens was rmOP or br1=01 Ps.
Therefore, the radius of curvature of the lens becomes smaller. In this case, the length of the arc, which is the spherical surface of the lens, is JO at room temperature.

If 11 is the case when the temperature is t° C. higher than normal temperature, and α is the coefficient of linear expansion of the lens, then it can be approximated as 1-0·(1+αt).

On the other hand 1. Even under low temperature conditions, the situation is the same as in the high temperature conditions described above, but the phenomenon is opposite. That is, the part of the lens frame 7 that has an expansion coefficient of 5 is
And of the material forming presser ring 1? Since tMhe is larger than the tensile coefficient, as the temperature decreases, the lens frame 2 and presser ring 1 contract, and the lens 7 tends to contract □, but the lens 7
The lens 7
, presser ring 1 cannot be contracted. This ib + thermal stress is generated inside the lens 7, and the lens contracts in the optical axis direction to cancel out the thermal response of and.As a result, the optical axis of the lens 7 is The upper spherical surface is at position P under normal temperature conditions, but under low temperature conditions it shifts to position P2VC, exhibiting a phenomenon in which the curvature of the lens becomes completely opposite to that of a lens with a curvature of 70 and a half. In this case, the arc length of the lens at room temperature is 112 when the temperature is t°C lower than at room temperature, and the #i1 expansion coefficient of the lens is α, then it can be approximated as 12≧IIo・(1−αt). Gate.

In such conventional lens holding mechanisms, the radius of curvature of the lens changes due to temperature changes, and even if the parts are assembled accurately at room temperature, the focal position of the lens may shift significantly depending on the temperature at which it is used. This was a cause of various combing aberrations. This problem is particularly severe in plastic lenses, which have relatively low temperature resistance.

゛ The present invention is the best way to eliminate some of the disadvantages of plastics that have relatively low temperature resistance. yriVyX? The objective is to construct a lens holding mechanism with strong temperature resistance that is not affected by temperature changes, and to expand the operating temperature range of the plastic lens. Another object of the present invention is to prevent the retaining ring 1 from loosening which occurs due to the relaxation of plastic lenses.

This is intended to eliminate the occurrence of rattling in the lenses.

That is, the present invention provides a lens holding mechanism that holds a lens within a lens frame with a holding ring, and a member having a small friction coefficient, such as a sheet member, is interposed at the abutting portion of the lens. The lens is characterized by a structure in which a steering damping agent is applied to absorb changes in the volume of the lens due to changes in temperature and the like.

゛Hereinafter, various embodiments applicable to the present invention will be described with reference to the drawings.

FIG. 5 shows a lens holding mechanism according to a first embodiment of the present invention, and FIG. 5A shows a side sectional view including the optical axis, and FIG.

In the same figure, the lens barrel mounting part 4, the lens frame 2, the screw s3, the fitting part 5, the holding ring 1, and the lens 7 are formed exactly the same as in the conventional method explained in FIG. ing. This means that the lens holding mechanism according to the present invention can be applied as is to the conventional general system, which improves productivity, reduces costs,
Furthermore, k is something that deserves special mention from the perspective of work performance.

First, the fitting part 5 formed on the inner wall of the lens frame body mounting part 4
A rear friction washer 9 is fitted into the rear friction washer 9.

has been done. Further, the material is a member having a small coefficient of friction, such as a Teflon (trade name) material, and the coefficient of friction is about μ=O,OS~0.15. In addition,
You are free to use other materials, but the coefficient of friction is μ
It is desirable to use resins and other materials with the same properties as those having properties in the range of 1 and 2 and a moderate amount of elasticity. Next, the plastic lens 7 is fitted from the plane side into the sewing frame trunk attachment part 5 and brought into contact with the rear friction sash 9. Then, the front friction washer 10 is inserted into the lens frame, brought into contact with the spherical side of the lens 7, and the presser ring 1 is fitted into the threaded portion 31 formed inside the lens frame 2. ,
, Yo Akira - 0 Yuwaratsuya □. Hold 122's 7. An exploded perspective view of each part in the above assembly is shown in Figure 5. However, in the lens holding mechanism assembled in this manner, the lens is held with the friction washers 9 and 10 interposed, so even if there is a temperature change during use, the lens will still expand due to the temperature change.・If the string is absorbed by the friction washers 9 and 10, it becomes busy. This is because the drag resistance between the lens 7 and the rear friction washer 9 and between the lens 7 and the front friction washer 100 is reduced because the friction coefficient of the friction washer is small as described above. Therefore, the lens 7 can be deformed in the radial direction even though there is a relative volume change due to a temperature change, so that the radius of curvature of the lens does not change and the lens is also prevented from shaking. .

6 and 7 show a second embodiment of the present invention, and both are side sectional views including the optical axis of the lens holding mechanism. The difference from the first embodiment described above is that the M of the lens 7
This point is formed by providing an outer edge portion 512 having a parallel surface around 1, and this parallel surface is formed perpendicular to the optical axis at 5, as is clear from No. 6 i. Other parts other than the shape of the lenses 7 can be implemented in exactly the same way as the first embodiment, so in FIGS. 6 and 7, the same parts as in FIG. 5 are given the same numbers, and detailed explanation thereof will be omitted. . In addition, in the second embodiment, the rear friction washer 9 and the front friction washer 1
As shown in FIG. 6, the lens 7 is held in such a way that the parallel surfaces of the outer edge 12 formed on the lens 7 are held in contact with each other.

By the way, in the second embodiment, the provision of the outer edge part '12 on the lens 7 is sufficient to prevent the regulation by the spherical surface of the lens as in the conventional method (see FIG. 1) described above, or in the first embodiment (see Diagram a
In order to eliminate the contact portion of the lens against the spherical surface, as shown in Fig. 7, the front friction washer 10 is interposed only between the lens 7 and the retainer ring 1, and the rear friction washer 9 is removed. You can get the first one. This is clear from the experimental data described below. Although FIG. 7 illustrates the case where only the front collapsing washer 10 is used, conversely, even if only the rear friction washer 9 is used, which is interposed between the lens 7 and the lens frame body attachment part 4. The result is all the same. Thus, in the second example, better results than those in the first example could be obtained. In order to clarify the effects of the present invention, actual measurement data of the radius of curvature of the lens in the second example will be listed below.

Table 1 Table 2 Table 3 Note) The friction washer is made of Teflon (trade name) material with a friction coefficient of μm O, OS ~ 0:15 (1st
Table ~ 3rd mist common).

Table 4 As described above, in the second embodiment, the radius of curvature of the lens hardly changes under any temperature conditions, such as room temperature, high temperature, and slightly low temperature, and this is shown in Tables 1 to 3. It is clear from In addition, as shown in Fig. 6, when both the rear friction washer 9 and the front friction washer 100 are used (the first
Table'), or even if one of the friction washers is used as shown in Figure 7 (Table 2 or Table 3),
As a result, there is no difference between VCit and VCit. Table 4 also lists actual measurements under the same conditions for the conventional method described above (see FIG. 1). Although in the conventional method the radius of curvature of the lens changes significantly under high or low temperature conditions, in the case of the second embodiment, the radius of curvature does not change at all, and the present invention It is easy to understand why the effect of this is so great.

The invention is further not limited to the above embodiments. Next, examples will be shown in which the shapes of the gods used in place of the friction washers are different. FIG. 8 shows a third embodiment according to the present invention, and shows a fourth embodiment in which a member with a small frictional mooring is used as a fragmentary member in place of the friction washer. Although the lens 7a is different in type from the lens 7 described above, the periphery of the lens is similar to that of the second embodiment (
An outer edge portion 12 similar to that shown in FIG. 6) is formed.

In the third embodiment, the friction washers 9 and 10 are made of the same material (only the shape is different).
It is also possible to attach strip-shaped fragment members 13 at equal intervals to the outer edge part 12 (see FIG. 8C) on a flat surface that includes the lens and does not block the light beam of the lens. Yo(・(Refer to Section 8-a).

It should be noted that these are just examples that can be implemented without impairing the effects of the present invention even if the shapes are different, and other shapes may be freely used. Although FIG. 8 shows only a single lens, assembly into the lens frame can be carried out in exactly the same way as the second embodiment (6th transmission). Also, FIG. The fourth embodiment shows a case where the lens is a long lens 7C, and in this case, the shape of the friction washers 9 and 10 used in the second (2) embodiment is adjusted to match the shape of the rectangular lens 7.゛Place the square piece with friction washer 1
6 shows what can be done. Furthermore, FIG. 10 shows the most extreme case of the fifth embodiment, in which the shape of the low-friction member interposed in the lens abutting portion according to the present invention is completely unrelated to the shape of the lens. This means that it is possible to do something like this, and it shows that even in such a case, the effects of the present invention can be enjoyed.

The third embodiment to the fifth embodiment described above are representative examples of the shape deformation of the friction washer used in the first embodiment or the second embodiment. It can be implemented with any shape as long as it does not affect the light or cause any problems such as not blocking the light beam of the lens system.

On the other hand, it is not limited to the above-mentioned yoke example,
As a sixth embodiment of the present invention, which is not shown in the drawings, there is a method of applying a predetermined thickness → friction damping agent (+l) in place of the sheet member K, such as the above-mentioned frictional pusher, on the lens contact area.
Ru. Even in this case, the effects of the present invention can still be enjoyed, and it is also possible to double mold the friction damping part, that is, the abutting part of the lens when molding the lens, or to insert it. Therefore, according to the lens holding mechanism according to the present invention, since the lens is held by interposing a member with low frictional resistance in the abutting portion of the lens, the lens holding mechanism according to the present invention can be easily applied based on temperature changes. (expansion of the lens)
It is possible to absorb shrinkage and prevent changes in the radius of curvature of the lens, and when an outer edge formed by a parallel surface is provided around the lens, the above member with low frictional resistance is provided only on one side of the lens. It can also be used and the same effect as when used on all the contact parts can be expected, and in this case there is an advantage that costs can be relatively reduced. In any aspect of the present invention according to the various embodiments, it is possible to prevent the shift of the focus position due to changes in the radius of curvature of the lens or the worsening of various aberrations. It is also possible to expand the temperature range in which it can be used.

Furthermore, in the present invention, the elasticity of the friction washer can be used to prevent a reduction in the loosening torque of the retaining ring, which conventionally occurs due to stress relaxation due to temperature changes, vibrations, etc. of plastics. Shakiness can also be removed. 'Furthermore, the present invention has the advantage that it can be directly applied to the conventional lens holding mechanism, and therefore brings many benefits in terms of mass production, cost reduction, and work efficiency. Therefore, the technical effects of the present invention are extremely large.

[Brief explanation of the drawing]

11 is a side sectional view including the optical axis showing an example of a conventional lens holding 1rIA structure. FIG. 2 is a partially enlarged view of the dashed-dotted circle A@50 in FIG. FIG. 3 is an explanatory diagram showing the adverse effects of the conventional lens holding mechanism at high temperatures. FIG. 4 is an explanatory diagram showing the adverse effects of the conventional lens holding mechanism at low temperatures. FIG. 5a is a side sectional view including the optical axis of a lens holding mechanism showing a first embodiment of the present invention. FIG. 5b is an exploded perspective view of the same figure. Figure 6 and M7-1m)-! , side cross section 0 and 8 including the optical axis of the lens holding mechanism showing the second embodiment of the present invention! %H1 Present Invention 7 Part 6 3rd Example - The lens is shown in the case where the example is applied, and FIG. 1A is a front view, FIG. ! FIG. 9 is a perspective view of a lens when the fourth embodiment according to the present invention is applied. FIG. 1θ shows a perspective view of the lens in the case where the fifth embodiment of the present invention is applied. 1... Holding ring 2... Lens frame number... Lens frame barrel attaching part 5 -... Fitting part 7.7a, Wb, 7c 1111@Lens・9... Rear friction washer iO・ee Front friction washer 11, 120, outer edge of lens with parallel surfaces 13...
i (rectangular) piece 1, material 14... (circular sheet shape>, piece member 15...; piece member c::. amount 16...deformed friction washer Fig. 1 @ Fig. 2 i13 Figure g4%' 1115f: A (CI) 0 (b) Procedural amendment February 4, 1980 Haruki Shimada, Commissioner of the Japan Patent Office 1, Indication of the case 1982 patent Kenbe No. 141367 2, Name of the invention Lens Retention Mechanism 3, Relationship with the case of the person making the amendment Patent Applicant Address: 2-46-2 Hatagaya, Shibuya-ku, Tokyo President and CEO Shigeo Kitamura 4, Agent 7, Subject of Amendment (1) ``In the Specification''"Claims" and "Invention,
``Detailed explanation'' column (2) Drawings - 8, Contents of amendment (1) The scope of claims is amended as shown in the attached sheet. (2) The statement "Clearance is zero" on page 31, line 19 of the specification is corrected to "design clearance." (3) The statement "applied relaxation" on page 6, line 20 of the specification is corrected to "stress relaxation." (4) The description from page 7, lines 3 to 8 of specification t1 is amended as follows. In other words, the present invention provides a lens holding mechanism for holding a lens within a lens frame with a holding ring.
It is characterized by correcting the influence of the radius of curvature of the lens due to temperature changes." (5) "The inner wall of the lens frame barrel mounting portion 4 was alerted" on page 8, line 2 of the specification. ◎ (6) Specification letter 81t (at line 813, the description "Mirror frame frame attachment part 5" is corrected to "Mirror frame body attachment part 4". (2) (7) In the 17th and 188th lines of the specification letter 8, the statement "Front friction washers...retained" was changed to "Front and rear friction washers 9 and 10 are interposed on both front and rear sides of the lens 7. (8) On page 9 of the specification, lines 9 to 13, ``Therefore...
・The description up to ``Prevented'' has been amended as follows. - [Thus, it is possible to correct the slight change in the radius of curvature due to temperature change, and it is also possible to prevent focus shift and worsening of aberrations due to temperature change, and to extend the operating temperature range of ID plastic lenses. Can be expanded. Furthermore, the front and rear friction washers 9 are used to reduce the loosening torque of the presser foot 111 that was caused by stress relaxation in the plastic.
．． (9) "Outer edge portion 12" on page 9, line 17 of the specification. 600) Specification No. 1
In the 6th and 8th lines of page 0, the words ``outer edge 12'' are corrected to read ``outer edge 11,'' respectively. Ql) Among the drawings attached to this application, Figures 1-1 and 2. The indicated position of number 4 in FIGS. 5 &, b, 6 and 7 is corrected according to the respective correction drawings. 9. List of attached documents (1) 1 attachment (2) 1 copy of corrected drawings a Claims (1) In a lens holding mechanism that holds a lens within a lens frame with a holding ring, 1. A lens holding mechanism, characterized in that a member having a small friction coefficient is interposed to compensate for the effect of temperature change on the radius of curvature of the lens. (2) The lens holding mechanism according to claim 1, wherein the member having a small friction coefficient is interposed between the lens and the lens frame mounting portion and/or the presser ring. 3) In a lens holding mechanism in which a lens is held in a lens frame by a holding ring, an outer part having a parallel surface is provided on the outer periphery of the lens, and an outer part is provided between the lens and the holding ring or the lens frame body part. A lens holding mechanism is characterized in that a member with a small frictional coefficient is interposed in the lens to compensate for the effect of temperature change on the radius of curvature of the lens. (4) The lens holding mechanism according to claim 1, 2, or 3, characterized in that it is a friction washer in a rectangular shape or a shape similar to these. (5) The lens holding device according to claim 1, 2 or 3, characterized in that the member having a small coefficient of friction is a plurality of fragment members. (6) The member having a small coefficient of friction Claims 1, 2 and 3, characterized in that the member is a sheet-like member.
4. The lens holding mechanism according to item 4 or '5. (7) Claim 1, wherein the member having a small coefficient of friction is a friction damping agent. The lens holding mechanism according to item 2 or 3. (81 Claim characterized in that the lens is a plastic lens! The lens holding mechanism according to item 1 or 3. '11゜＠Figure 1 @Figure 2Figure 5 (0) 0 (b )

Claims (1)

[Scope of Claims] (1) In a lens holding mechanism that holds a lens in a lens frame with a presser ring, a member with a small coefficient of friction is interposed at the abutting portion of the lens to prevent temperature changes. A lens holding mechanism configured to be able to absorb changes in the volume of the lens. (2) The lens holding mechanism according to claim 211, item 1, d, characterized in that the lens is made of a plastic lens. (3) The lens holding mechanism according to claim 11 or 2, characterized in that the lens is shaped by providing an outer edge portion with parallel surfaces around the periphery of the lens. (4) A patent patent characterized in that the above-mentioned member is formed in the lens frame and is interposed between the lens frame mounting surface and the lens, and/or between the lens and the presser foot. Lens holding mechanism described in section. (5) The lens holding mechanism according to claim 1 or 4, characterized in that the above member is formed by a sheet member VC'c. (9) The lens holding mechanism according to claim 1 or 4, wherein the member is formed by applying a linear attenuator to the still contacting portion of the lens. (7) f Claim (8) characterized in that said member is formed into a loop shape along the abutting portion of the lens. Claim (8) The above-mentioned member is formed by a plurality of fragment members. Section or Section 14 or Section 5 or Section 6
Lens as described in Section - Standby S,