JPH0550402U - Plastic lens - Google Patents

Abstract

(57) [Abstract] [Purpose] It is possible to eliminate the distortion caused by temperature changes during use of plastic lenses with weak temperature resistance. [Structure] A plastic lens has a cutout recess along the outer peripheral surface thereof. In addition, a through hole is provided inside the plastic lens along the outer periphery thereof and penetrating in the optical axis direction.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a plastic lens, and more particularly to a plastic lens that can cope with temperature changes after being held in a lens frame.

[0002]

[Prior Art]

 Conventionally, this type of plastic lens is as shown in FIG. 7, and the plastic lens 113 itself has not been processed at all. A state where such a plastic lens is held by the lens frame is shown in FIGS. FIG. 5 is a vertical sectional view showing a state where the plastic lens is held by the lens frame, and FIG. 6 is a partially enlarged vertical sectional view of FIG.

In FIGS. 5 and 6, 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 while the lens barrel 111 of the lens frame 111 is attached. After abutting against the portion 114, 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 inner surface of the press ring 112. The contact surface 117 formed in the above is pressed against the outer peripheral surface 117 on the front side of the plastic lens 113 to fix the plastic lens 113 to the lens frame 111.

[0004]

[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 fitting margin is taken into consideration in consideration of changes in high temperature, the margin will deteriorate the optical axis accuracy and optical performance of the lens, so the fitting margin will be set to the linear expansion coefficient of the plastic lens. It is not possible to have a range that can be handled.

From the above, in the case of a structure in which a plastic lens is housed in a lens frame by a holding ring, which has a conventional structure, distortion deformation occurs at a high temperature, and the focus position is greatly deviated as compared with that at a normal temperature. However, there is a problem in that various optical aberrations occur and the optical performance deteriorates. The present invention has been made in view of such conventional problems, and an object thereof is to widen the operating temperature range of a plastic lens having low temperature resistance and to prevent distortion when a high temperature changes. It is to provide a plastic lens that can be stored and fixed in the lens frame without deformation.

[0007]

[Means for Solving the Problems]

 For the above purpose, in the present invention, the first means for solving the problem is to have a notch concave portion along the outer peripheral direction on the outer peripheral end surface of the lens, and the inside of the lens is provided along the outer periphery of the lens and The second means for solving the problem is to have a through hole that penetrates in the axial direction. Further, a notched recess formed on the outer peripheral end face of the lens along the outer peripheral direction thereof, and a through hole penetrating in the optical axis direction along the outer periphery of the lens inside the lens, and the notched recess and the through hole. A third means for solving the problem is that the respective circumferential end portions of the above are overlapped in the radial direction.

[0008]

[Action]

 In the present invention, the flange of a plastic lens, which has a higher linear expansion coefficient than the lens frame to be held and is weak in temperature resistance, is provided with a notch concave portion along the outer peripheral direction thereof, and / or inside thereof, and at the outer periphery thereof. Since the through-holes are provided so as to penetrate along the optical axis direction, it is possible to prevent distortion deformation in the radial direction due to thermal stress when the lens frame holding the plastic lens becomes hot. Furthermore, since the notched recesses and the through-holes have respective circumferential end portions that overlap in the radial direction, it is possible to prevent further strain deformation.

The expansion of the flange of the plastic lens sandwiched between the lens frame body-attached surface and the retaining ring in the thrust direction is negligible because it is slight.

[0010]

【Example】

 Embodiments of the present invention will be described below with reference to the drawings. 1 to 4 show an embodiment of the present invention, and FIG. 4 is a perspective view of a plastic lens in the present invention. The plastic lens 3 is formed with a notch concave portion 9 along the outer peripheral end face of the lens in the flange portion 11 so as to divide the outer periphery into three equal parts. Further, a through hole 8 is formed inside along the outer periphery and penetrating in the optical axis direction of the plastic lens 3 in the same manner as described above so as to be divided into three equal parts along the outer periphery. The circumferential end portions of the cutout recess 9 and the through hole 8 are arranged to overlap each other in the radial direction.

The plastic lens 3 configured as described above is held as shown in FIGS. 1 to 3. A description will be given below with reference to FIGS. 1 to 3. A fitting portion 7 for holding the plastic lens 3, a lens barrel mounting surface 6, and a screw portion 4 are formed on the inner peripheral portion of the lens frame 1. The holding ring 2 for holding the plastic lens 3 has a threaded portion 4 ′ that is screwed with the threaded portion 4 formed on the lens frame 1 on the outer periphery thereof.

The above-mentioned members are attached as follows. The plastic lens 3 is fitted into the fitting portion 7, and then the screw 4 ′ of the presser ring 2 is screwed into the screw portion 4 of the lens frame 1 and screwed into the plastic lens 3 side. The attaching surface 6 and the back of the lens collar 11 are closely attached and fixed.

As a result, a fitting gap is formed by the notch 9 between the outer peripheral surface of the plastic lens 3 and the fitting portion 7 of the lens frame. The fitting gap, the through hole 8, and the overlapping portion 10 formed by the fitting gap and the through hole 8 thus formed absorb the expansion of the plastic lens 3 at a high temperature and prevent the occurrence of lens distortion. is doing.

In the present embodiment, the notched concave portions 9 are equally formed at three locations on the outer peripheral surface, and the through holes are similarly formed at three locations along the outer peripheral surface, but the present invention is not limited to this. Instead, it may be provided at a plurality of locations, such as at least two locations.

[0015]

[Effect of the device]

 As described above, according to the present invention, the plastic lens can be prevented from being distorted and deformed due to the thermal expansion in the radial direction even in a high temperature atmosphere. It has the effect of preventing deterioration. Further, since the loose fitting backlash which has been set in consideration of the distortion due to thermal expansion is unnecessary, the backlash of the plastic lens can be minimized. Therefore, the influence of the looseness on the optical axis accuracy of the lens can be minimized and the optical performance can be easily secured.

[Brief description of drawings]

FIG. 1 is a partially omitted vertical sectional view showing a state in which a plastic lens according to the present invention is held by a lens frame,

FIG. 2 is an enlarged vertical sectional view of a part of FIG.

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

FIG. 4 is a perspective view of a plastic lens according to the present invention,

FIG. 5 is a partially omitted vertical sectional view showing a state in which a conventional plastic lens is held by a lens frame,

6 is an enlarged vertical sectional view of a part of FIG. 5,

FIG. 7 is a perspective view of a conventional plastic lens.

[Explanation of symbols]

3 plastic lens 8 through hole 9 notch recess 11 collar part

Claims (3)

[Scope of utility model registration request] 1. A plastic lens having a notched concave portion along the outer peripheral direction on the outer peripheral end surface of the lens. 2. A plastic lens having a through hole formed inside the lens and extending along the outer circumference of the lens in the optical axis direction. 3. A lens has a cutout recess formed on an outer peripheral end face thereof along an outer peripheral direction thereof, and a through hole formed inside the lens, the through hole extending along the outer periphery of the lens and penetrating in the optical axis direction. A plastic lens, characterized in that the notched recesses and the respective circumferential ends of the through holes are formed so as to overlap each other in the radial direction.