JPS5988706A - Plastic lens with collar - Google Patents

Abstract

PURPOSE:To prevent the generation of compressive stress and clatter in a plastic lens on account of a change in temp. by providing a grade to one end face of the collar of said lens and providing the same grade to the engaging surface of a lens barrel or a retaining ring as well. CONSTITUTION:A grade is provided at a prescribed angle theta to one end face of the collar 12 of a plastic lens 11. A graded surface 16 having the same angle theta is also provided to the engaging surface of a lens barrel 15. A recess 17 having the inside diameter larger by delta than the outside diameter of the lens 11 is provided on the inside surface of the barrel 15. The graded surface 13 of the lens 11 is engaged with the graded surface 16 of the barrel 15 and is fixed by a retaining ring 20. Even if the lens 11 expands or contracts on account of a change in temp., the lens 11 expands or contracts freely along the graded surface 16 and the flat end face 21 of the ring 20 and therefore the compressive stress and clatter of the lens are prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a plastic lens with a flange for cameras, etc., and more specifically, a plastic lens with a flange that has a slope at the edge so as to be able to cope with temperature changes. Regarding.

BACKGROUND TECHNOLOGY AND PROBLEMS Conventionally, in order to fix a plastic lens (usually PMMA (polymethyl methacrylate), PS (polystyrene), PC (polycarbonate), etc.) to an aluminum lens barrel, a method as shown in Fig. 1A was used. A glass lens that is fixed by inserting the outer edge of the lens (1) into the four parts (3) on the inner surface of the lens barrel (2), and screwing the aluminum retainer ring (5) into the female screw (4) also provided on the inner surface. There is a method similar to that shown in Figure 1B, or a method in which the lens is provided with a brim as shown in Figure 1B.
Fit Nobba (81 (91) into the recess (3) on the inner surface of the lens barrel (2), and screw the retainer (5) into the female thread (4) on the inner surface as well. (3) It is fixed inside, and the flange (8) (91) has the role of a spacer to regulate the distance between lenses and the role of fitting based on the outer diameter standard.However, the aluminum of the lens barrel material and the plastic of the lens material For example, the coefficient of thermal expansion of aluminum is 2.3.
X10, whereas the thermal expansion coefficient of PMMA is <S
, 0X10, so there is a big difference between them.

Therefore, in a high temperature environment, the plastic lens is compressed in the radial direction and in the thickness direction of the brim (t direction in Figure 3) due to thermal expansion, creating compressive stress, and in a low temperature environment, the plastic lens is compressed due to thermal expansion. In addition to creating an outer diameter gap in the radial direction, a gap also occurs in the thickness direction of the brim, which causes play in the lens or lens barrel, causing optical axis misalignment and changes in focal length. It was occurring.

Purpose of the Invention The present invention has been made in view of the above circumstances, and its purpose is to:
To provide a plastic lens with a flange that does not generate compressive stress or stiffness even if there is a temperature change in the usage environment.

SUMMARY OF THE INVENTION In order to achieve the above-mentioned objects, the present invention provides a plastic lens with a flange with a predetermined slope on the end face of at least one of the flange. Alternatively, by providing the same slope on the retaining surface of the presser ring, and by engaging these sloped surfaces with each other and fixing the lens barrel to the lens barrel with the presser ring, the lens conforms to the slope according to temperature changes. It is constructed so that it can be expanded and contracted along the line.

With the above configuration, even if there is a temperature change in the usage environment, compressive stress or stiffness will not occur in the lens.

Example Embodiments of the present invention will be described below based on the drawings.

First, the first embodiment of the present invention will be explained.
As shown in the figure and Fig. 2B, the lens 01) Nogge (IZ
One end surface of the collar 02+ is provided with a slope of a predetermined angle θ, and the other end surface of the collar 02+ is formed as a flat surface without any slope. On the other hand, on the inner surface of the lens barrel 0■, an inclined surface (having an IQ and whose inner diameter is larger than the outer diameter of the lens 0υ by δ) is formed on its inner end surface at the same angle θ as the above-mentioned slope. . On the inner surface of the end of the lens barrel (151) adjacent to this recess 07), there is formed a female thread ag whose inner diameter is slightly larger than the inner diameter of the fourth part θη.

Then, insert the lens 01) into the lens barrel 05) from the female thread side end of the entire lens barrel 09, engage its sloped surface 03) with the sloped surface (16) inside the lens barrel 0■, and align it with the outer peripheral surface. Screw the presser ring with the threaded θ blade into the female thread θ thread. In this way, the lens Qll is fixed to the lens barrel 05) with a required gap δ maintained between its outer peripheral surface and the inner peripheral surface at the recess α of the lens barrel a9. Even if there is a gap δ, since the sloped surface 09 of the lens 0υ is engaged with the lens barrel (+ uniform sloped surface 1Q), the center of the lens αυ will not shift due to rattling.

Next, the gradient θ is the combined direction of the radial expansion (or contraction) ΔD/2 of the lens 01) and the thickness direction expansion (or yield) Δt of the boxwood az in FIG. That is, it is determined that e=tm, 7., - in the direction of expansion and contraction of 2'. Also, δ is set to 20C and is usually 45
t: A gap that can accommodate expansion at t.

Therefore, even if the lens I thermally expands or contracts due to exposure to high or low temperatures, the lens aυ freely expands and contracts along the lens barrel (+51 θ, inclined surface oe) and the flat end surface Cυ of the presser head. There is a gap δ between the outer circumferential surface of the lens (Iυ) and the inner circumferential surface of the lens barrel (151), and since it expands and contracts freely along the slope, compressive stress is generated in the lens aυ, and the lens barrel (151) As you can see, the center of the lens does not shift.

Also, what is shown in FIG. 4 is a second embodiment of the present invention.

The difference between this second embodiment and the first embodiment is that there are slopes (23) (24) in opposite directions on both end surfaces of the collar U.
are provided respectively, and the gradients θ1 and θ2 are assigned to the required gradient θ so that θ=01+02. Although not shown, these sloped surfaces (second floor (
The inner end surface of the lens barrel and one end surface of the presser ring, which are engaged with 2), are formed into inclined surfaces of .theta.1 and .theta.2, respectively. That is, this second
In the example, the expansion/contraction Δ in the thickness direction of boxwood (12+
t is allocated to both ends so that Δt=Δt, +Δt2, and the directions in which this amount of expansion and contraction and the amount of expansion and contraction in the radial direction are combined are defined as θ1 and θ2, respectively. Talented person θ1
and θ2 are the directions in which the lens expands and contracts, so this second
Also in the embodiment, the lens α° C. can freely expand and contract along the above-mentioned gradients θ1 and θ2 directions in response to changes in temperature.

Next, in the third embodiment of the present invention shown in FIG. 5, sloped surfaces (25) aa+ in the same direction are provided at both ends of the brim,
The slopes θ5 and θ4 are determined to be θ-03-04 with respect to the required slope θ in the first embodiment. That is, in this third embodiment, the expansion and contraction Δt in the thickness direction of the brim is Δt - Δt3 - Δt4, the amount of expansion and contraction on the slope surface (25) is allocated to be larger than Δt by Δt4, and this excess amount Δt4 is applied to the slope surface. 06). Therefore, as in the first and second embodiments, the lens 0υ can freely expand and contract along the gradient (25) (:2G) in response to changes in temperature.

On the other hand, since the lens barrel itself expands, contracts, and deforms due to temperature changes, the lens is also generally affected by this and curves, causing a change in focal length. However, in this third embodiment, as described above, the lens (111) has a slope θ6 that exceeds the required expansion/contraction amount at one end (25) of the boxwood (I'lJ), and a slope θ6 at the other end (06).
), the lens 01) expands and contracts along gradients in the same direction with a gradient θ4 equal to the above-mentioned excess, so when it expands and contracts along these gradients, a change occurs in the curvature of the lens 01). Therefore, if this curvature and the curvature due to the deformation of the lens barrel itself are the same in opposite directions, the two should always cancel out.

That is, in this third embodiment, if the amount of excess of the gradient and the side of this excess are determined appropriately, the deformation of the lens caused by the temperature change of the lens barrel can be absorbed, Automatic focal length adjustment can be performed.

As described in detail, according to the present invention, at least one end face of the flange is provided with a predetermined slope, and the retaining face of the lens barrel and/or presser foot with which this slope is engaged is also provided with the same slope. The lens is configured to be able to expand and contract along the gradient in response to changes in temperature by providing a gradient of , engaging these gradient surfaces with each other, and fixing the lens barrel to the lens barrel with the presser ring. Even if there is a temperature change in the environment in which the lens is used, compressive stress or stiffness will not occur in the lens as in the case of conventional lenses.

Therefore, according to the present invention, it is possible to provide an extremely reliable and advantageous plastic lens that is not subjected to excessive force due to temperature changes, nor is its function impaired. .

[Brief explanation of drawings]

The figure shows an example in which the BA of the present invention is applied to a camera lens. Figures 1A and 1B are partial longitudinal sectional views showing the conventional example, and Figure 2A is a first embodiment of the present invention. %'Z2B is a partial longitudinal sectional view showing only the lens shown in the same figure, Figure 6 is a diagram showing the relationship between the dimensions, expansion/contraction amount, and slope of the lens in Figure 2B. 4 and 5 are partial vertical sectional views of lenses showing second and third embodiments of the present invention. In addition, in the symbols used in the drawings, (Ill...... Lens (IZ
−・・・・・・・・・・・・Tsuba (+, '5) (2%
, ~(26)... Gradient surface (of the lens) (] Even...
・・・・・・・・・・・・ Lens barrel aO・・・・・・・・・・
...Slope surface (of the lens barrel) (20) ...
......The presser foot is broken. Agent Masaru Doyo Yoshio Tsune Kao Toshiki Sugiura (9125- Unexamined Japanese Patent Publication No. 59-8870G (4) Figure 3 ρ Figure 4 Figure 5 (Spontaneous) Procedural Amendment Document January 13, 1980 Patent Office Mr. Commissioner, 1. Indication of the case, 1981 Special Patent Application No. 200113, Tokyo Parts River IK Kitashinagawa 6-07-35 (218), Sony Corporation 6, Amendment 1. Number of inventions increased from this 7, Details subject to amendment. H!l?, column 8, content of amendment (2), r45 CJ on page 5, line 11 of the specification, as “4
I corrected it to "about 5C". (31. On page 7, lines 9 to 11 of the specification, "On the other hand, a change in temperature causes a change." (4) The curvature of the old lens on page 7, lines 16 to 18 of the specification... ......The curvature corrects J by ``a change in the front-rear position of the lens aD.Therefore, this change in the front-rear position and the change in focal length due to temperature change''. (5) "The lens barrel...
・・・・・・・・・・・・・Absorbs deformation,'' is corrected to ``Absorbs fluctuations in the focal length of the lens due to temperature changes.''-That's all-

Claims (1)

[Claims] In a plastic lens with a flange, the end face of at least 10,000 flange is provided with a predetermined slope, and the retaining surface of the lens barrel and/or presser ring with which this slope engages is also provided with the same slope. The lens is constructed so that the lens can expand and contract along the slope in response to temperature changes by engaging the sloped surfaces of the lens with each other and fixing it to the lens barrel with the presser foot. plastic lens.