JPH09211280A - Cemented lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cemented lens which is easily assembled and can has its spacing error and eccentricity error suppressed. SOLUTION: The optical function surface 4 of an aspherical lens 2 and the optical function surface 9 of a spherical lens 8 face each other; and the optical function surface 4 is aspherical and the optical function surface 9 is spherical. The lens 2 and 8 are cemented together having their optical axes aligned with each other. The lenses 2 and 8 are formed, for example, by molding optical plastic materials such as plastic or glass. At this time, neither of the lenses 2 and 8 has a conventional rib part at the outer peripheral edge, so separation type metal molds need not be used and united metal molds are used. An annular cemented surface 5 is formed at the peripheral part of the optical function surface 4 of the aspherical lens 2. The cemented surface 5 is provided in an area outside the effective optical path of the aspherical lens 2. This cemented surface 5 is cemented to the peripheral part of the optical function surface 9 of the spherical lens 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cemented lens in which two or more lenses fixed to a lens barrel are combined.

[0002]

2. Description of the Related Art Conventionally, when a cemented lens is constructed by combining two or more lenses, a rib portion is provided on the outer peripheral edge of each lens, and the rib portions are joined to combine two or more lenses. (See, for example, Japanese Utility Model Laid-Open No. 3-5120).

[0003]

However, in the conventional cemented lens, there is a problem that it is difficult to obtain the accuracy of the distance between the lenses due to the structure of the mold for manufacturing each lens. Since it is necessary to separate the mold from the optical function part of the lens and the rib part, when the mold is assembled, the optical function part mold and the rib part mold are likely to be misaligned, and the optical function part and the rib part This is because the positional accuracy of the parts cannot be secured sufficiently. Furthermore, if the coaxiality of the optical function mold and the rib mold cannot be manufactured with high precision, there is a problem that an eccentricity error of the lens also occurs.

Therefore, an object of the present invention is to provide a cemented lens which is easy to assemble and which can suppress the spacing error and the eccentricity error.

[0005]

In order to achieve the above object, the cemented lens according to the present invention is such that at least one of the two optical function surfaces of the two adjacent lenses facing each other is an aspherical surface. And an annular cemented surface is formed on the peripheral portion of the aspherical surface, and the two adjacent lenses are cemented at this cemented surface.

Further, the cemented lens according to the present invention has two optical function surfaces of two adjacent lenses facing each other.
At least one of the optical functional surfaces is a spherical surface within the optical required range, and an aspherical surface is outside the optical required range of the peripheral portion of the optical functional surface, and the spherical surface and the aspherical surface are smoothly and continuously connected. In addition, an annular cemented surface is formed outside the optically required range of the aspherical surface, and the two adjacent lenses are cemented at this cemented surface.

It is preferable that the lens having the aspherical surface is a plastic lens. Further, it is preferable that the annular cemented surface is provided in a region outside the effective optical path of the lens having an aspherical surface. Further, it is preferable that the lens facing the lens having the aspherical surface is a spherical lens.

[0008]

With the above construction, it is not necessary to separate the metal mold for manufacturing the lens into the rib portion and the optical function portion, and a lens in which a gap error and an eccentricity error are hard to occur can be obtained.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a cemented lens according to the present invention will be described below with reference to the accompanying drawings. [First Embodiment, FIGS. 1 to 5] As shown in FIG. 1, the cemented lens 1 is composed of an aspherical lens 2 and a spherical lens 8. The aspherical lens 2 has optical function surfaces 3 and 4, and the spherical lens 8 has optical function surfaces 9 and 10.
The optical functional surface 4 of the aspherical lens 2 and the optical functional surface 9 of the spherical lens 8 face each other, the optical functional surface 4 is an aspherical surface, and the optical functional surface 9 is a spherical surface.

The lenses 2 and 8 are cemented so that their optical axes coincide with each other. The lenses 2 and 8 are formed, for example, by molding an optical plastic material such as plastic or glass. At this time, since there is no conventional rib portion on the outer peripheral edge of each lens 2, 8, it is not necessary to use a separate type mold, and an integrated mold is used. An annular joint surface 5 is formed around the optical function surface 4 of the aspherical lens 2. The cemented surface 5 is provided in a region outside the effective optical path of the aspherical lens 2. The bonding surface 5 is bonded to the peripheral portion of the optical function surface 9 of the spherical lens 8 with an ultraviolet curable adhesive or the like.

In the aspherical lens 2, a chamfered portion 6 is provided on the outer peripheral portion of the cemented surface 5 in order to prevent excess adhesive applied to the cemented surface 5 from flowing into the optical function surface 4. .
As shown in FIG. 2, the optical function surface 4 of the aspherical lens 2 is
It is an aspherical surface within the optical required range P at the center of the lens 2. In FIG. 2, the dotted line S indicates a spherical shape. This cemented lens 1 has a cylindrical lens barrel 1 as shown in FIG.
5 That is, the cemented lens 1 has the lens barrel 15
After being positioned using the fitting portion 16 with the lens and the abutting portion 17 of the lens, an adhesive 1 such as an ultraviolet curing type
8 is applied to the outer peripheral edge of the optical function surface 10 of the spherical lens 8,
It is fixed in the lens barrel 15 by being cured.

In the cemented lens 1 having the above-mentioned structure, since an integrated mold is used when manufacturing the lenses 2 and 8, the lenses 2 and 8 in which the spacing error and the eccentricity error are hard to occur can be obtained. . The cemented surface 5 is the aspherical lens 2
Since it is a part of the optical function surface 4, the cemented lens 1 is processed with high precision and suppresses the spacing error and the eccentricity error.
Is obtained. That is, the cemented lens 1 includes each lens 2,
The gap error and the eccentricity error can be suppressed only by highly accurate machining of the eight optical function surfaces 4 and 9.

This will be described in more detail. Whereas the conventional gap error of the cemented lens is the alignment error between the optical function mold and the rib mold, the gap error of the cemented lens 1 of the first embodiment is the lens 2, 8 optical function surface 4,
The surface precision error is 9. And, generally, the surface accuracy of the optical function surface of the lens is higher than the positioning accuracy of the mold.

There are two types of eccentricity error: parallel eccentricity error and tilt eccentricity error. The parallel decentering error is an error in which the optical axis 22 of each lens element 21 is deviated from the optical axis 23 of the optical system in parallel to the optical axis 23, as shown in FIG. The tilt / eccentricity error is an error in which the optical axis of each lens element 21 is tilted with respect to the optical axis 23 from the optical axis 23 of the optical system, as shown in FIG. The tilt decentering error of the conventional cemented lens is the tilt decentering error of the optical function surface of each lens plus the tilt decentering error of the rib portion, whereas the tilt decentering error of the cemented lens 1 is Only the tilt / eccentricity error of the optical function surfaces 4 and 9 of 2 and 8 is sufficient. On the other hand, the parallel decentering error of the cemented lens 1 is a parallel decentering error of the optical function surfaces 4 and 9 of the lenses 2 and 8, and is not different from the parallel decentering error of the conventional cemented lens.

Further, in the cemented lens 1, even when the tilt and decentering errors of the optical function surfaces 4 and 9 of the lenses 2 and 8 are large,
Since the tilt / eccentricity error can be eliminated simply by adjusting the cemented angle between the lenses 2 and 8, the cemented lens 1 with high accuracy can be obtained.

[Second Embodiment, FIG. 6] As shown in FIG. 6, the cemented lens 31 includes a lens 32 and a spherical lens 38.
It consists of. The optical function surface 33 of the lens 32 and the optical function surface 39 of the spherical lens 38 face each other, and the optical axes of the lenses 32 and 38 coincide with each other. The optical function surface 33 of the lens 32 is a spherical surface within the optical required range P of the central portion of the lens 32, and is an aspherical surface outside the optical required range P. The spherical surface within the optical required range P and the aspherical surface outside the optical required range P are continuously and smoothly connected. Thereby, the processing accuracy of the aspherical surface can be made equal to the highly accurate processing accuracy of the spherical surface within the optical required range P.

An annular joint surface 34 is formed outside the aspherical optical required range P, specifically, at the edge of the lens 32. The cemented surface 34 is the optical function surface 3 of the spherical lens 38.
The lens 32 and the spherical lens 38 are integrated by being bonded to the peripheral portion of 9 by an adhesive. The cemented lens 31 configured as described above has the same operation and effect as the cemented lens 1 of the first embodiment.

[Third Embodiment, FIG. 7] As shown in FIG. 7, the cemented lens 41 includes a lens 42 and a spherical lens 48.
It consists of. The optical function surface 43 of the lens 42 and the optical function surface 49 of the spherical lens 48 face each other, and the optical axes of the lenses 42 and 48 coincide with each other. The optical function surface 43 of the lens 42 is a spherical surface within the optical required range P of the central portion of the lens 42, and is an aspherical surface outside the optical required range P. The spherical surface within the optical required range P and the aspherical surface outside the optical required range P are continuously and smoothly connected. Thereby, the processing accuracy of the aspherical surface can be made equal to the highly accurate processing accuracy of the spherical surface within the optical required range P.

An annular joint surface 44 is formed outside the aspherical optical required range P, specifically, at the edge of the lens 42. The cemented surface 44 is the optical function surface 4 of the spherical lens 48.
The lens 42 and the spherical lens 48 are integrated by being bonded to the peripheral portion of 9 by an adhesive. The cemented lens 41 having the above configuration has the same effects as the cemented lens 1 of the first embodiment.

[Other Embodiments] The cemented lens according to the present invention is not limited to the above-mentioned embodiment, but can be variously modified within the scope of the gist thereof. As each lens to be combined, a lens such as a concave lens, a convex lens, or a meniscus lens is arbitrarily selected according to the specifications.

The surface shape within the optical required range may be an aspherical surface or a spherical surface. At this time, it suffices that the surface within the optically required range and the surface outside the required range are continuously and smoothly connected so that the surface accuracy can be easily obtained.

[0022]

As is apparent from the above description, according to the present invention, two adjacent lenses are cemented with each other by the aspherical ring cemented surface, so that the lens interval is improved and the eccentricity error is suppressed. be able to. The surface accuracy can be improved by smoothly and continuously connecting the spherical surface within the optical required range and the aspherical surface outside the optical required range.

By molding a lens having an aspherical surface with a plastic lens, the cost of the cemented lens can be reduced. Furthermore, by using a spherical lens as the companion lens cemented to the lens having an aspherical surface, it is possible to eliminate the tilt / eccentricity error only by adjusting the cemented angle of both lenses.

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment of a cemented lens according to the present invention.

FIG. 2 is a partially enlarged cross-sectional view for explaining a cemented state of the cemented lens shown in FIG.

3 is a cross-sectional view showing a state in which the cemented lens shown in FIG. 1 is fixed to a lens barrel.

FIG. 4 is a sectional view for explaining parallel eccentricity.

FIG. 5 is a sectional view for explaining tilt eccentricity.

FIG. 6 is a partially enlarged sectional view showing a second embodiment of the cemented lens according to the present invention.

FIG. 7 is a partially enlarged sectional view showing a third embodiment of the cemented lens according to the present invention.

[Explanation of symbols]

 1, 31, 41 ... Bonded lens 2, 8, 32, 38, 42, 48 ... Lens 4, 9, 33, 39, 43, 49 ... Optical functional surface 5, 34, 44 ... Bonded surface P ... Optically required range

Claims (5)

[Claims] 1. An optical function surface of at least one of two optical function surfaces facing each other of two adjacent lenses is an aspherical surface, and an annular bonding surface is formed in a peripheral portion of the aspherical surface. 2. The cemented lens according to claim 2, wherein the two adjacent lenses are cemented. 2. Of two optical functional surfaces facing each other of two adjacent lenses, at least one optical functional surface is a spherical surface within an optical required range, and an optical required range of a peripheral portion of this optical functional surface. The outside is an aspherical surface, the spherical surface and the aspherical surface are smoothly and continuously connected, and an annular cemented surface is formed outside the optically required range of the aspherical surface, and the two adjacent lenses at the cemented surface. A cemented lens characterized by being cemented with. 3. The lens according to claim 1, wherein the lens having the aspherical surface is a plastic lens.
The cemented lens described. 4. The cemented lens according to claim 1, wherein the annular cemented surface is provided in a region outside the effective optical path of the lens having the aspherical surface. 5. The cemented lens according to claim 1, wherein the lens facing the lens having the aspherical surface is a spherical lens.