Optical element having integrated optical lens and lens...

Details Optical element having integrated optical lens and lens... Optical element having integrated optical lens and lens...

2001-06-14

2003-05-20

Epps, Georgia (Department: 2873)

Optical: systems and elements

Lens

With support

C065S319000

Reexamination Certificate

active

06567224

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical element having an integrated optical lens and lens holder, and to a production method for the optical element. More particularly, the present invention relates to a structure for holding an optical lens and a lens holder when press-molding the optical lens.
2. Description of the Related Art
In various fields of optical communication devices, optical information reading devices, and the like, optical elements in which an optical lens is held by a lens holder are used. In a well-known technique for producing such a conventional optical element, an optical lens is combined with the inner surface of a lens holder by press fitting when being press-molded from an optical glass material.
In the conventional optical element, a cylindrical or spherical lens material made of optical glass is placed in a lens holder made of metal, such as stainless steel, and generally shaped like a hollow cylinder; is heated and softened by a heating member; is pressed and deformed by being clamped by dies from above and below; and is press-fitted in the lens holder, whereby the lens material and the lens holder are combined. Moreover, lens optical surfaces are formed with an optical axis in the direction of the cylindrical axis of the lens holder by transferring the die surfaces onto the lens material.
As shown in
FIGS. 3 and 4
however, in the above-described conventional optical element, gaps L
1
and L
2
of approximately 20 &mgr;m are formed between the inner diameter of an inner wall
13
a
of a lens holder
13
into which a lens material
14
is press-fitted and the outer diameters of dies
11
and
12
for press-molding the lens material
14
. Therefore, when the lens material
14
is press-molded, portions
14
a
and
14
b
of the deformed lens material
14
protrude in an annular ring outward through the gaps L
1
and L
2
, and the shapes of outer peripheral edge surfaces
15
c
and
15
d
of lens optical surfaces
15
a
and
15
b
connected to the inner wall
13
a
of the lens holder
13
form a discontinuity and become disjointed and non-uniform.
For this reason, the protruding portions
14
a
and
14
b
of the lens material
14
formed at the outer peripheral edge surfaces
15
c
and
15
d
of the lens optical surfaces
15
a
an
15
b
may be broken and chipped due to vibration or external force, and glass powder formed thereby may adhere to the lens optical surfaces
15
a
and
15
b.
SUMMARY OF THE INVENTION
The present invention solves the above problems. An object of the present invention is to provide an optical element having an integrated optical lens and lens holder that prevents chipping and adhesion of glass powder resulting from protrusion of a part of an outer peripheral edge surface of a lens optical surface connected to the inner wall of the lens holder when a lens material is press-molded. It is another object of the present invention to provide a production method for the optical element.
In order to overcome the above problems, according to an aspect of the present invention, there is provided an optical element including a lens holder made of metal and shaped like a hollow cylinder, and an optical lens integrally held by an inner wall portion of the lens holder and having a lens optical surface at an opening in the direction of the optical axis, wherein an annular projecting portion is formed in the inner wall portion of the lens holder and adjacent to the opening, and an outer peripheral edge surface of the lens optical surface is placed under the projecting portion and is pressed in contact with the projecting portion over the entire periphery.
In this case, the shape of the outer peripheral edge surface of the lens optical surface connected to the inner wall portion of the lens holder is made continuous and uniform. This can prevent the lens optical surface from being broken and chipped due to vibration or external force and can prevent glass powder from adhering to the lens optical surface.
Preferably, a part of the projecting portion is buried in the outer peripheral edge surface of the lens optical surface. This allows the lens holder to reliably hold the optical lens.
According to another aspect of the present invention, there is provided an optical element production method including the steps of forming an annular projecting portion adjacent to an opening of an inner wall portion of a lens holder shaped like a hollow cylinder, inserting a lens material made of optical glass in the cylinder of the lens holder, press-fitting the lens material in the cylinder by heating, and pressing and deforming by a die, thereby forming a lens optical surface at the opening in the direction of the optical axis, and deforming the projecting portion by the die so that a part of the projecting portion is buried in an outer peripheral edge surface of the lens optical surface.
In this case, no gap is formed between the inner diameter of the inner wall portion of the lens holder and the outer diameter of the die when the lens material is press-molded, the deformed lens material does not partly protrude outward, and the shape of the outer peripheral edge surface of the lens optical surface connected to the inner wall portion of the lens holder can be made continuous and uniform.
According to a further aspect of the present invention, there is provided an optical element production method including the steps of inserting a lens material made of optical glass in a cylindrical portion of a lens holder shaped like a hollow cylinder, press-fitting the lens material in the cylindrical portion by heating, and pressing and deforming by a die, thereby forming a lens optical surface at an opening in the direction of the optical axis, extending a die surface for pressing a pressed surface of the lens material outside the inner wall of the cylindrical portion of the lens holder when pressing and deforming the lens material, and performing molding while an outer peripheral edge surface of the lens optical surface and an outer flat surface of the cylindrical portion of the lens holder are covered with the die surface.
In this case, no gap is formed between the inner wall of the lens holder and the die when the lens material is press-molded, the deformed lens material does not partly protrude outward, and the shape of the outer peripheral edge surface of the lens optical surface connected to the inner wall of the lens holder can be made continuous and uniform.
Further objects, features, and advantages of the present invention will become apparent from the following description of the preferred embodiments with reference to the attached drawings.


REFERENCES:
patent: 4891053 (1990-01-01), Bartman et al.
patent: 5188652 (1993-02-01), Nakamura et al.
patent: 5805361 (1998-09-01), Mortimoto et al.
patent: 5851255 (1998-12-01), Ohtsuki et al.

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