JPS6148801A - Multifocal molded lens and its manufacture - Google Patents

Abstract

PURPOSE:To improve optical performance by putting a heat-softened glass material in a metallic mold and molding a lens in one body by pressing. CONSTITUTION:The multifocal lens 6 is so formed that a lens 62 which has less curvature than a lens 61 is molded in the center part of the spherical surface of the lens 61 in one body by using the glass material. The upper mold 10 of a metallic mold for press molding which is used to manufacture the multifocal lens is formed in the shape of the bottom surface part of the lens 6 and the lower mold 7 consists of two bodies, i.e. external mold 8 and internal mold 9 as female molds corresponding to the spherical part of the lens 61 and the spherical part of the lens 62. Then, pellets of the glass material are heated and softened in a furnace and put in this metallic mold, thereby finishing the multifocal molded lens 6 by press molding. Consequently, the eccentricity of the lens optical axis is reduced greatly and neither polishing nor cementing is necessary, so the cost is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a method for manufacturing a molded lens, particularly a lens advantageous for use as a tip lens of an illumination fiber such as an endoscope, and its shape.

Conventional technology Normally, the basic shape of an optical lens is a single lens consisting of two spherical surfaces, but such a single lens has various aberrations, so its performance as a lens cannot be fully utilized.
Composite lenses, which have improved performance by bonding two or more lenses together, are often used.

In particular, a glass multifocal compound lens consisting of a plurality of convex lens parts as shown in FIGS. 5 and 6 is used, for example, as the tip lens of a 7-eyeper for illumination of an endoscope. (Refer to Utility Model Application Publication No. 55-8941)
To manufacture this, two or more lenses were polished separately and then glued together. That is, in FIG. 5, lenses 1 and 2 are pasted together, and the sixth
In the figure, lenses 3, 4.5 are bonded together.

However, in the conventional method of bonding lenses using adhesive, it is very elegant to align the optical axes of each lens completely, and the optical axis of the finished compound lens is It has been almost impossible to prevent the serious drawbacks of significantly reducing performance and causing image blurring.

Also, when performing the lens bonding work, the periphery of the lens 2 in the case of Fig. 4, the lens 4,
5, it is difficult to prevent the occurrence of paris, and the optical performance is affected not only from the mismatch of the optical axes of each lens, but also from the perspective of light scattering due to paris around the cemented lens. This has the disadvantage of causing deterioration of the lens and canceling out the design advantages of using a compound lens.Furthermore, the work involved polishing multiple lenses separately and then joining them together. Therefore, it has had various problems such as being expensive in terms of manufacturing cost.

OBJECTS OF THE INVENTION It is an object of the present invention to eliminate the drawbacks of the conventional method for arranging a compound lens, and to obtain a multifocal lens with high optical performance and no optical axis deviation.

Summary of the Invention The present invention is to obtain a multifocal molded lens in place of a composite lens by placing a heat-softened glass material in a mold and press-molding it (secondarily, by adhesion) to replace a composite lens.

Example Hereinafter, the present invention will be explained in detail with reference to Examples.

FIG. 2 shows a multifocal molded lens showing a first embodiment of the present invention. This multifocal lens 6 has a lens 62 having a slightly smaller curvature at the center of the spherical surface of a lens 61 made of a glass material. It is molded into one piece.

FIG. 1 is a partial cross-sectional view of a press molding mold for making such a multifocal molded lens, in which 10 is an upper mold, 7 is a lower mold, and the upper mold 10 is shaped like the bottom of the lens 6. The mold 7 is composed of two parts, an outer mold 8 and an inner mold 9, each of which has a lens 61.
It is a female type corresponding to the spherical part of the lens B2 and the shape of the spherical part of the lens B2.

Therefore, first, a pellet-shaped glass material is heated in a furnace to soften it until the pellet has a viscosity of 10'1 to 1066 Boaz, and then placed in this mold and pressed from above and below (mold forming). Six multifocal molded lenses as shown in FIG. 2 are completed.

Note that the shape of the lens is not necessarily limited to plano-convex lenses;
If necessary, a biconvex lens or a combination lens of spherical and aspherical surfaces can also be used.

The multifocal lens molded in one piece in this way is different from the multifocal lens made of the conventional compound lens mentioned above, because it is a complete multifocal lens with no bonded parts. As long as there are no cracks in the parts corresponding to the connection points of each lens in a compound lens, and the centers of the molds are aligned, there is no need to polish each lens or bond each lens together. Therefore, no deviation of the optical axis occurs.

Therefore, there is no scattering of light from the boundaries of each lens portion, and there is no blurring of the image due to misalignment of the optical axis, making it possible to obtain a multifocal lens with excellent optical performance.

FIG. 3 shows a lens showing a second embodiment, and this multifocal molded lens 11 has a spherical portion 111 on one side.
A convex portion 112 having a slightly smaller curvature at the center thereof and a convex portion 113 having a slightly smaller curvature than the two convex portions 112 at the center thereof are integrally molded.

The mold of the apparatus for manufacturing this lens uses the lower mold 7 of the lens mold of the first embodiment explained in FIG.
Can be easily press molded.

Further, FIG. 4 shows a multifocal molded lens showing a third embodiment, in which the peripheral part of the single-sided spherical part 121 of the lens 12
A convex portion 122 with a slightly small curvature is integrally molded.

The mold for molding this lens is basically the same as the mold described above, and can be press-molded using a mold that is divided into upper and lower halves, with the concave and convex portions reversed to those of the multifocal mold lens.

As described in detail, the multifocal lens according to the present invention is made by integrally forming a large number of lenses with different focal lengths by molding, so it does not work like a conventional compound lens made by bonding. Since there is no loss due to scattering of light due to imperfections in the connection or bonding portions of the lens parts, and there is no need for a step of bonding each lens, the optical axis does not shift from one lens to another.

In other words, by accurately assembling the split molds, it is possible to minimize the eccentricity of the optical axis of the lens, and since it is a one-piece glass mold, it is difficult to prevent this with conventional bonding methods. There is no cracking at the sharp angles around the lens, and as mentioned above, there is no need for polishing or bonding processes, so it is possible to significantly reduce costs.

Furthermore, when these multifocal lenses are used, for example, as an illumination lens for an endoscope, sufficient brightness can be obtained up to the periphery within the observation field of view, and extremely uniform illumination can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view of a press molding die, FIG.
FIG. 4 is a side view of the lens of the third embodiment, and FIGS. 5 and 6 are side views of a compound lens produced by a conventional method. 6.11.12... Multifocal molded lens 7...
・・・・・・・・・Lower mold 10・・・・・・・・・・・・Upper mold patent applicant Olympus Optical Industry Co., Ltd. (Spontaneous writing of procedural amendments) January 23, 1985 1 , Description of the case 1971 Patent Application No. 171217 2 Name of the invention Multifocal molded lens and its manufacturing method 3 Person making the amendment Relationship to the case Patent applicant Address 2-43 Hatagaya, Shibuya-ku, Tokyo No. 2 No. 4, Agent 7jili Correct Contents (1) The statement "Figure 4 y" on page 3, lines 6-7 of the specification is amended to 1, Figure 5, 1. (2) Specification The description ``r Figure 5 yo'' in the 7th line of page 3 is changed to ``
Figure 6 is corrected. (3) The statement "1011-1055 poise." on page 5, line 5 of the specification is corrected to ml Q7-1055 poise. (4) "Multifocal molded lens" on page 5, line 8 of the specification. The description that 6J is corrected as r multifocal molded lens 6.

Claims (3)

[Claims] (1) A multifocal molded lens characterized in that one or both surfaces of the lens are formed of two or more spherical surfaces. (2) The multifocal molded lens according to claim 1, wherein one or both surfaces of the lens are formed of any combination of flat, spherical, and aspherical surfaces. (3) A method for producing a multifocal molded lens, which comprises heating and softening a glass lens material and then molding it in a mold of a press molding machine.