JPH0545615U - Lens holding device - Google Patents

Abstract

(57) [Summary] [Purpose] When holding plastic lenses with weak temperature resistance, prevent lens distortion even at high temperatures. [Structure] An elastic member that fits an outer circumference of a lens and fits an inner circumference of a lens frame is provided. .

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a lens holding device, and more particularly to a lens holding device in which a plastic lens is housed in a lens frame, the plastic lens is restricted in its radial direction and thrust direction, and fixed to the lens frame.

[0002]

[Prior Art]

 A conventional device of this type has a structure as shown in FIGS. In FIG. 5, when the plastic lens 113 is housed in the lens frame 111, the plastic lens 113 is fitted into the fitting portion 115 of the lens frame 111, but abuts against the lens barrel attachment portion 114 of the lens frame 111. After that, the screw 116 formed on the outer circumference of the press ring 112 is screwed into the screw 116 formed on the inner circumference of the lens frame 111, and the screw 116 is screwed into the contact surface formed on the inner surface of the press ring 112. 117 is pressed against the front outer peripheral surface 117 of the plastic lens 113 to fix the plastic lens 113 to the lens frame 111.

[0003]

[Problems to be solved by the device]

 In the conventional technology as described above, when the assembly of the plastic lens with respect to the lens frame is performed at room temperature and then exposed to a high temperature atmosphere, the linear expansion coefficient of the plastic lens molding material causes the lens frame and the press ring to be molded. Since it is larger than the linear expansion coefficient of the material, the fitting margin between the plastic lens and the lens frame is lost, and this condition is regulated.

Therefore, as the temperature rises, the plastic lens tends to expand in the radial direction, but thermal expansion occurs inside because the lens frame is prevented from expanding. Then, the thermal stress is converted into the thrust direction that is not restricted by expansion, and causes the plastic lens to undergo strain deformation. In addition, if a large mating margin is provided in consideration of changes in high temperature, the margin deteriorates the optical axis accuracy and optical performance of the lens, so the mating margin corresponds to the linear expansion coefficient of the plastic lens. You can't have it as you would.

From the above, when the plastic lens has the conventional structure and is housed in the lens frame by the retaining ring, distortion deformation occurs at a high temperature, and the focus position may be largely deviated as compared with that at a normal temperature. However, there was a problem that various optical aberrations were aggravated. The present invention has been made in view of such conventional problems, and an object of the present invention is to widen the operating temperature range of a plastic lens having low temperature resistance so that the plastic lens is not affected by a change in high temperature. An object of the present invention is to provide a lens holding device that can be housed and fixed in a lens frame without distortion and deformation of the lens.

[0006]

[Means for solving the problem]

 To achieve the above object, the present invention provides a lens holding device for accommodating and fixing a lens in a lens frame, comprising an elastic member for fitting the outer circumference of the lens and fitting the inner circumference of the lens frame, The elastic member has a notch concave portion along the circumferential direction on the fitting surface of the lens and the lens frame as means for solving the problem, and the notch concave portions formed on the inner and outer circumferences of the elastic member are mutually The means for solving the problem is that the both ends are formed to overlap in the radial direction.

[0007]

[Action]

 In the present invention, the radial expansion of the plastic lens that occurs when the temperature of the device becomes high is absorbed by the thickness portion of the elastic member in which the notch recess is formed. Deformation can be prevented. Further, since the expansion in the thrust direction of the outer peripheral portion of the plastic lens sandwiched between the lens frame body-attached surface and the elastic member is slight, it can be sufficiently absorbed by the deformation of the flange portion of the elastic member. Can prevent distortion deformation of plastic lens

[0008]

【Example】

 The present invention will be described below based on the embodiments shown in the drawings. 1 to 3 show an embodiment of the present invention in which a fitting portion 10 for holding a plastic lens 4, a lens barrel mounting surface 9 and a screw portion 5 are formed on an inner peripheral portion of a lens frame 1. Is made. The elastic member 3 for fitting the outer peripheral portion thereof into the fitting portion 10 has a flange portion 11 for holding the plastic lens 4 at the inner peripheral end portion, and has a substantially L-shaped cross section. Further, the inner peripheral portion and the outer peripheral portion of the elastic member 3 are formed with three notched concave portions along the respective circumferential portions, and the notched concave end of the inner peripheral portion and the notched concave end of the outer peripheral portion are formed. A portion 14 that overlaps in the radial direction is provided. The holding ring 6 for holding the elastic member 3 and the plastic lens 4 on the fitting portion 10 of the lens frame and the lens barrel attachment surface 9 is provided with a screw 5 ′ that is screwed with the screw portion 5 formed on the lens frame 1. Is formed on the outer periphery of the.

The above members are attached as follows. The plastic lens 4 is fitted into the lens fitting portion 8 of the inner L-shaped portion of the elastic member 3 and fitted into the fitting portion 10 of the lens frame. After that, the screw portion 5 ′ of the presser ring 2 is screwed onto the screw portion 5 of the lens frame 1 and screwed into the plastic lens 4 side, so that the lens barrel mounting surface 9 of the lens frame 1 and the lens back surface outer peripheral surface 7 ′, Also, the inner end surface of the elastic member 3 and the outer peripheral surface 7 on the front side of the lens are closely attached and fixed.

As a result, a fitting gap 12 is formed between the outer peripheral surface of the plastic lens 4 and the lens fitting portion of the elastic member 3. A fitting gap 13 is also formed between the outer peripheral surface of the elastic member 3 and the fitting portion 10 of the lens frame 1. The fitting gaps 12 and 13 and the flange portion thus formed absorb the expansion of the plastic lens 4 at a high temperature and prevent the occurrence of lens distortion.

In the present embodiment, the notched recesses are formed at three locations on the elastic member 3 and on the outer peripheral surface, respectively. However, the present invention is not limited to this, and for example, only the outer peripheral surface may be provided. It is sufficient that there are at least two or more locations.

[0012]

[Effect of the device]

 As described above, according to the present invention, even if a plastic lens is used in a high temperature atmosphere, it is possible to eliminate the influence of the thermal expansion in the radial direction, and thus it is possible to prevent the plastic lens from being deformed and deformed. .. Therefore, there is an effect that the focus position at normal temperature and high temperature and deterioration of various optical aberrations can be prevented. Furthermore, since the present invention allows the fitting margin of the plastic lens to be small, the accuracy of the optical axis of the lens can be minimized due to the fitting margin, so that the optical performance can be easily ensured.

[Brief description of drawings]

1 is a longitudinal sectional view of a device according to the present invention,

FIG. 2 is a partially enlarged vertical sectional view of a fitting portion in FIG.

FIG. 3 is a sectional view taken along the line A-A ′ in FIG.

FIG. 4 is a vertical sectional view of a conventional device,

5 is a partially enlarged cross-sectional view of a fitting portion in FIG.

[Explanation of symbols]

1 Lens Frame 2 Holding Ring 3 Elastic Member 4 Plastic Lens 11 Collar 12 and 13 Fitting Gap 14 Part where Cutout Recesses Overlap

Claims (2)

[Scope of utility model registration request] 1. A lens holding device for accommodating and fixing a lens in a lens frame, comprising: an elastic member fitted to the outer periphery of the lens and fitted to the inner periphery of the lens frame, wherein the elastic member is the lens. And a lens holding device having a notched concave portion along a circumferential direction on a fitting surface with a lens frame. 2. The lens holding device according to claim 1, wherein the cutout recesses formed on the inner and outer circumferences of the elastic member are formed such that both ends of the cutout recesses overlap each other in the radial direction.