JPH01167708A - Lens barrel for plastic lens - Google Patents

Abstract

PURPOSE:To obtain environmental resistance and optical characteristics which has no practical problem by structuring the plastic lens so that the lens does not have no irreversible plastic deformation even if expanding or contracting owing to environmental variation. CONSTITUTION:An irreducible necessary gap is set between the plastic lens 1 and lens barrel 2 so as to absorb the deformation due to the environmental variation. Then cuts or holes are formed in radial directions of the lens barrel 2 and lens assembling jigs 3 contact the outer periphery of the plastic lens 1 directly through the cuts or holes from outside the lens barrel 2 to move the lens 1 and adjust its position in the lens barrel 2. The center axis of the lens barrel 2 is aligned with the position where the jigs 3 abut on the lens barrel 2 and the position of the plastic lens 1 is adjusted directly by the jigs 3 to hold the lens 1 in the lens barrel 2. Consequently, the plastic lens 1 is obtained which has satisfactory optical characteristics and no problem in terms of the environmental resistance.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention improves the environmental resistance of plastic lenses,
The present invention relates to a lens barrel for a plastic lens that is suitable for ensuring its optical properties.

[Conventional technology]

A plastic lens has a specific gravity of about 173 compared to a glass lens, so it is best to make lenses with a larger diameter plastic.
This provides the effect of weight reduction. However, plastic lenses have a problem in that they expand and contract more due to environmental changes, such as changes in temperature, humidity, etc., than glass lenses. When applying a plastic lens to a lens assembly, it is necessary to ensure a holding precision equivalent to or higher than that of a glass lens, and to prevent irreversible stress (ffi property) deformation from being applied to the plastic lens. For this,
Conventionally, a structure has been adopted in which a plastic lens is held using an elastic member as disclosed in, for example, Japanese Patent Laid-Open No. 59-26706.

[Problem that the invention seeks to solve]

The above-mentioned conventional technology does not take into consideration the fact that the holding precision of the plastic lens decreases due to the elastic member used to absorb deformation, and there is a problem in that it is not possible to obtain practically satisfactory optical performance. A large zoom lens used for a video camera or the like has a diameter of about 40,111 mm. For a glass lens with a diameter of 35111 mm, the expansion and contraction distance in the diametrical direction is approximately 70 μm. Therefore, in order to absorb the deformation, the amount of deformation of the elastic member provided by the above technique becomes large, and from the viewpoint of deformation stress, it is necessary to use a material with a low elastic modulus.

When a material with a low elastic modulus is used, the radial dimension varies greatly from the viewpoint of processing accuracy. During assembly, the plastic lens may be arbitrarily displaced within its variations.

The other lenses that make up the assembly are placed along the center of the lens barrel.The center axis of the lens barrel is the optical axis of a normal lens assembly.The center of the lens barrel is located at the center of the plastic lens. The deviation with respect to the optical axis is a deviation with respect to the optical axis, that is, eccentricity. The eccentricity usually needs to be suppressed to about 10 to 20 μm.

In order to ensure the environmental resistance of the glass lens, the present invention provides a plastic lens that absorbs deformation, does not cause stress deformation, can be assembled without eccentricity, and has practically satisfactory optical properties. The purpose is to provide a lens barrel for

[Means for solving problems]

In order to solve the above problems, in the present invention, a minimum gap is set between the plastic lens and the lens barrel in order to absorb deformation due to environmental changes, and multiple cuts are made in the radial direction of the lens barrel. A notch or hole is provided, and through these, the lens vertical positioning jig directly contacts the outer periphery of the plastic lens from the outside of the lens barrel, and the lens is placed inside the lens barrel t1. The movement can now be adjusted. Make the center axis of the lens barrel and the part where the jig engages and abuts the lens barrel coaxially. The structure is such that the position of the plastic lens can be directly moved and adjusted using a jig, and after the lens is held in the lens barrel, the jig can be removed.

[Effect]

Assembly work shall be performed under standard environments. Regarding temperature durability, there are now almost no problems due to the materials and shapes of the plastic lenses and lens barrels. Rather, the biggest problem is hygroscopic expansion in high-temperature environments. During assembly, as described above, the eccentricity of the classic lens is removed using an assembly jig that has a part that contacts the plastic lens and a part that engages with a specific part of the lens barrel to hold the lens barrel coaxially. If this is done, there will be no obstacle to the expansion of an equivalent plastic lens in the radial direction due to the gap ζ between the toolastic lens and the inner surface of the lens barrel, and no deformation stress will occur.

In this way, a lens assembly including a plastic lens having satisfactory optical flexibility and no problem in environmental resistance can be obtained.

〔Example〕

FIG. 1 is a sectional view perpendicular to the axis of the mortar barrel ζ of the first embodiment of the present invention, in which 1 is a plastic lens, 2 is a lens barrel that holds the plastic lens inside, and 3 is a jig for positioning the plastic lens. It is. The inner diameter of the lens barrel 2 is 70 μm larger than the outer diameter of the plastic lens 1. The jig 3 contacts the outer periphery of the plastic lens 1 through a notch 2' provided in the lens barrel 2, and at the same time The assembly of a zero-order lens using this embodiment that engages with the tube 2 will be explained in detail with reference to FIG. FIG. 2 is a sectional view taken along a plane including the central axis of the lens barrel, that is, a 1-1' cross-sectional view shown in FIG. As can be seen from these figures, the plastic lens 1 is held by the lens press 4I. 5 is lens barrel 2
5' indicates the center of the plastic lens 1.

When the plastic lens 1 is assembled into the lens barrel 2, due to the radial gap between the lens barrel 2 and the plastic lens 1, the center 5' of the plastic lens 1 is aligned with the center 5' of the lens barrel 2 as shown by the solid line, as shown by the broken line. It's off. A jig 6 is pressed against this plastic lens 1, and the lens barrel 2 and jig S are fitted together. Fitting portion 15 between jig 5 and lens barrel 2. The jig 5 and the plastic lens coupling part 16 are made coaxially at the center of the jig. The plastic lens 1 is moved by a jig 3 until its center coincides with the center 5 of the lens barrel 2. In this way, a gap 6 is secured between the plastic lens 1 and the lens barrel 2. In this state, the plastic lens 1 is positioned and held by the lens holder 4, and then the jig 5 is removed.

The operation of this embodiment will be explained below with reference to Figure 8@6.

Figure 3 is a cross-sectional view taken along line 1-1' after the jig has been removed, with the plastic lens 1 maintaining a gap 6 with respect to the lens barrel 2, and the holding cuff 8 holder being held by the lens holder 4. . In this figure, when the plastic lens 1 absorbs moisture and expands due to changes in the humidity of the environment, the plastic lens 1 is deformed in the radial direction within the range of the gap 6. The amount of deformation in the thickness direction is 11II for the diameter of plastic lens 1, which is 65mm.
+ is 1/35. Since the amount of deformation is proportional to the length, expansion in the thickness direction is not a problem.

FIG. 4 shows the distance between ll1i6 and the holding cuff by the lens presser 4. The figure shows the result after moisture absorption after being left in a constant temperature chamber at 95% relative humidity of °C for one day. 9 is stress deformation of the lens surface dimension, 1
0 indicates a change in diameter.

Figure 4←) shows the gap 6 on the horizontal axis and the stress deformation of the lens surface dimension of the plastic lens 1 on the vertical axis, 9. As shown, when the gap 6 is 15 μm or less (8 in the figure), the lens surface dimension It is greatly deformed. When the plastic lens 1 of this embodiment is left in the thermostatic chamber for one day, as shown in FIG. 4(c), the diameter change 10 reaches 15 μm or more. In this figure, the horizontal axis shows the number of days left in the thermostatic oven, and the vertical axis shows the amount of diameter change 10 of the plastic lens 1. From this figure, it can be seen that if left for 4 days or more, it expands by about 65 μm in diameter.

Therefore, in this embodiment, the gap 6 is set to 35 degrees. FIG. 4(b) shows the relationship between the holding cuff by the lens presser 4 and the deformation 9 of the lens surface dimension, and shows that this deformation becomes large when the holding force exceeds 2 kg. Therefore, in this example, the bag was installed so that the holding force was 1 kgf. Note that this holding force is based on the flange surface of the plastic lens 1 (see Fig. 4).
Since it also depends on the shape of 11) in d) and the shape of the plastic lens 1, the appropriate holding force value will be different for other plastic lenses.

As explained above, in this embodiment, the gap 6 is 55 μm.
It was found that if one holding cuff was 1 kg, there would be no problem with humidity characteristics. Furthermore, since the center of the plastic lens 1 can be aligned with the center of the cylinder 2 using the jig 3, it has become possible to ensure optical characteristics. Even when the plastic lens 1 repeatedly expanded and contracted due to changes in humidity, no new eccentricity occurred because the plastic lens 1 was deformed in a similar manner.

FIG. 5 is a sectional view taken along the plane ζ including the central axis of the acute part of the second embodiment of the present invention. The symbols are the same as in FIG.

This embodiment differs from the first embodiment in that the arm portion 12 of the lens holder 4 can be designed to be longer, and the holding portion of the plastic lens 1 of the lens barrel 2 is flat. The operation is similar to that of the first embodiment. In addition to the effects similar to those of the first embodiment, this embodiment has the holding part of the plastic lens 1 on one plane, so that the lens barrel 2&! This has the effect of making it easier to manage dimensions during production.

No. 6 (g(a) shows a similar sectional view of the third embodiment of the present invention, and FIG. 6) is a perspective view of the lens holder 4 and the one-last lens 1. The symbols are the same as in FIG. This embodiment differs in that the outer circumference of the plastic lens 1 has approximately the same diameter as the outer circumference of the lens barrel 2, and the jig 3 has a simple cylindrical shape. The operation is similar to that of the first embodiment. In this example,
In addition to the effects of the first embodiment, the simple shape of the jig 3 has the effect that a high degree of h1 can be easily obtained.

FIG. 7 shows a similar cross-sectional view of a fourth embodiment of the invention. The symbols are the same as in FIG. This embodiment is different in that a screw flange 14 is provided on the lens holder 4 and lens barrel 2, and the plastic lens 1 is held by screwing them together. The functions and effects are similar to those of the first embodiment.

〔Effect of the invention〕

As explained above, according to the present invention, even if the plastic lens expands or contracts due to environmental changes, stress that would cause irreversible plastic deformation of the plastic lens is not generated. Since the lens and lens barrel can be decentered during assembly, there is no deterioration of the optical properties.Therefore, environmental resistance is achieved, and optical properties with no difference in practical use can be obtained.

[Brief explanation of the drawing]

Figure 1 shows the present invention No. 15j! FIG. 2 is a sectional view taken along a plane perpendicular to the axis of the lens barrel of the embodiment, FIG. 4(a) is a diagram showing the stress deformation of the surface dimension of the glass lens with the horizontal axis representing the gap between the lens and the lens barrel and the vertical axis, and FIG. 4(b) is a diagram showing the lens holder. A diagram showing the relationship between holding force and deformation of lens surface dimensions, Figure 4(c)
is a diagram showing the number of days left in a high-temperature, high-humidity constant temperature bath on the horizontal axis, and the amount of change in diameter of the plastic lens on the vertical axis, FIG. 4(d) is an explanatory diagram of deformation, etc. of the plastic lens used in the example,
FIG. 5 is a sectional view taken along a plane including the central axis of the lens barrel of the second embodiment of the present invention, FIG. 6(b) is a similar sectional view of the third embodiment of the invention, and FIG. FIG. 7 is a perspective view of a lens holder and a plastic lens, and FIG. 7 is a 151-degree cross-sectional view of the fourth embodiment of the present invention. 1... Glass lens 2... Lens barrel 3...
Assembly jig 4... Lens holder agent Patent attorney Ogawa Urinary man Closing 1 Atane 21 A 3 Picture No. 4-Fig.) (d-) Half 5 °C mouth 5 Otsu Fig.

Claims (1)

[Claims] 1. In a plastic lens barrel that holds a lens set including a plastic lens inside, a plurality of notches or holes are provided in the radial direction of the lens barrel, and the plastic lens mirror is inserted through these notches or holes. 1. A lens barrel for a plastic lens, characterized in that the position inside the barrel can be adjusted by directly contacting the lens from the outside of the lens barrel. 2. The plastic according to claim 1, characterized in that a portion is provided on the outside of the lens barrel to engage with a lens assembly jig and to cause the jig to hold the lens barrel coaxially. Lens barrel. 3. The lens barrel for a plastic lens according to claim 1, wherein the diameter of the inner surface of the lens barrel is larger than the diameter of the plastic lens by a predetermined length over the entire circumference of the plastic lens.