U.S. patent application number 16/421038 was filed with the patent office on 2020-05-14 for optical element and imaging lens.
The applicant listed for this patent is KANTATSU CO., LTD.. Invention is credited to Shigeru ENDO, Tatsuya OOUCHI.
Application Number | 20200150421 16/421038 |
Document ID | / |
Family ID | 68659785 |
Filed Date | 2020-05-14 |
![](/patent/app/20200150421/US20200150421A1-20200514-D00000.png)
![](/patent/app/20200150421/US20200150421A1-20200514-D00001.png)
![](/patent/app/20200150421/US20200150421A1-20200514-D00002.png)
![](/patent/app/20200150421/US20200150421A1-20200514-D00003.png)
![](/patent/app/20200150421/US20200150421A1-20200514-D00004.png)
![](/patent/app/20200150421/US20200150421A1-20200514-D00005.png)
![](/patent/app/20200150421/US20200150421A1-20200514-D00006.png)
United States Patent
Application |
20200150421 |
Kind Code |
A1 |
OOUCHI; Tatsuya ; et
al. |
May 14, 2020 |
OPTICAL ELEMENT AND IMAGING LENS
Abstract
An object is to provide an optical element and an imaging lens
that reproduce clear images by restraining ghosting, flare, and/or
similar occurrences caused by unwanted light reflected by the outer
circumference surface of an edge of the optical element. An optical
element 100 includes an optical effective portion 101 and an edge
102. The edge 102 is located around the optical effective portion
101 and has an outer circumference surface 103. The outer
circumference surface 103 includes roughened portions 200. An
imaging lens uses the optical element 100.
Inventors: |
OOUCHI; Tatsuya;
(Sukagawa-city, JP) ; ENDO; Shigeru;
(Sukagawa-city, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KANTATSU CO., LTD. |
Yaita-shi |
|
TW |
|
|
Family ID: |
68659785 |
Appl. No.: |
16/421038 |
Filed: |
May 23, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G02B 13/0045 20130101;
G02B 27/0018 20130101 |
International
Class: |
G02B 27/00 20060101
G02B027/00; G02B 13/00 20060101 G02B013/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 23, 2018 |
JP |
2018-099067 |
Claims
1. An optical element comprising: an optical effective portion; and
an edge located around the optical effective portion and having an
outer circumference surface, the outer circumference surface
comprising a roughened portion.
2. The optical element according to claim 1, wherein the roughened
portion has a unit shape comprising a protrusion and a depression,
and the unit shape comprises a repetition of equal to or more than
ten unit shapes.
3. The optical element according to claim 1, wherein the roughened
portion protrudes in a radiation direction directed from an optical
axis of the optical element toward the outer circumference surface,
and has a protrusion height of equal to or more than 0.01 mm.
4. The optical element according to claim 1, wherein the roughened
portion comprises a depression and a protrusion, the depression or
the protrusion extending in an extension direction in which the
optical axis extends, the extension direction being parallel to the
optical axis.
5. The optical element according to claim 1, wherein the roughened
portion comprises a depression and a protrusion, the depression or
the protrusion extending in an extension direction in which the
optical axis extends, the extension direction having an angle
relative to the optical axis.
6. The optical element according to claim 1, wherein the roughened
portion has a continuous shape extending over the outer
circumference surface.
7. The optical element according to claim 1, wherein the roughened
portion comprises an arcuate depression and an arcuate protrusion
each having a radius of equal to or more than 0.03 mm.
8. An imaging lens comprising the optical element according to
claim 1.
9. An imaging lens comprising the optical element according to
claim 2.
10. An imaging lens comprising the optical element according to
claim 3.
11. An imaging lens comprising the optical element according to
claim 4.
12. An imaging lens comprising the optical element according to
claim 5.
13. An imaging lens comprising the optical element according to
claim 6.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority under 35 U.S.C.
.sctn. 119 to Japanese Patent Application No. 2018-099067, filed
May 23, 2018. The contents of this application are incorporated
herein by reference in their entirety.
BACKGROUND OF THE INVENTION
Field of the Invention
[0002] The present invention relates to an optical element used in
an imaging device and relates to an imaging lens using the optical
element.
Discussion of the Background
[0003] In recent years, a variety of products such as information
terminals have been equipped with camera functions.
[0004] For cameras built in these information terminals, there is a
need for imaging lenses capable of taking clear images, with
eliminated or minimized ghosting and flare. In order to eliminate
or minimize ghosting and flare, it is important to restrain
unwanted light, which does not contribute to image formation.
[0005] Patent documents 1 and 2 disclose techniques to restrain
unwanted light.
[0006] Patent document 1 discloses an optical element incorporated
in a photographing optical system. The optical element includes an
effective diameter area, an outside effective diameter area, and an
outer circumference surface. The effective diameter area is
centered around a photographing optical axis, and permits an
effective light flux that contributes to image formation to pass
through the effective diameter area. The outside effective diameter
area surrounds the effective diameter area. The outer circumference
surface surrounds the outside effective diameter area. At least a
part of the outer circumference surface in its thickness direction
or circumferential direction is a non-parallel surface having an
angle relative to the photographing optical axis. When a ray of
light enters the optical element through the object-side surface of
the optical element and is reflected on the image-side surface of
the optical element to become incident on and reflected by the
outer circumference surface, the non-parallel surface prevents the
reflected ray of light from becoming incident on the image side of
the optical element.
[0007] Patent document 2 discloses a lens unit that includes a
photographing optical system and a photographing optical system
holder. The photographing optical system includes a plurality of
optical elements and forms an optical image of an object. The
photographing optical system holder holds the photographing optical
system. At least one optical element among the plurality of optical
elements includes an effective region portion, a non-effective
region portion, an engagement depression or an engagement
protrusion, and a scattering portion. The effective region portion
permits a light flux from an object to pass through the effective
region portion. The non-effective region portion surrounds the
effective region portion in an orthogonal direction orthogonal to
an optical axis of the photographing optical system. The engagement
depression or the engagement protrusion is located between the
effective region portion and the non-effective region portion in
the orthogonal direction, and is engaged with an adjacent optical
element so that the optical axis of the at least one optical
element and the optical axis of the adjacent optical element
coincide. The scattering portion is located on the outer
circumference surface of the non-effective region portion and
scatters light. The term scattering portion is recognized as: "The
scattering portion is an embossed layer formed by roughening the
outer circumference surface of the non-effective region portion.
The embossed layer has a surface roughness of equal to or less than
approximately 10 .mu.m, in ten-point average roughness, preferably
approximately 4 to 6 .mu.m. Surfaces having the specified surface
roughnesses can be formed using a roughness die such as #1003,
available from AYAMADAI CO., LTD." (see paragraph [0033] of patent
document 2).
RELATED ART DOCUMENTS
Patent Documents
[0008] [Patent document 1] JP 2010-164755A
[0009] [Patent document 2] JP 2015-90484A
Problems to be Solved by the Invention
[0010] In the optical element recited in patent document 1, at
least a part of the outer circumference surface in its thickness
direction or circumferential direction is a non-parallel surface
having an angle relative to the photographing optical axis. With
this configuration, the object of patent document 1 is to control
reflection light away from the imaging element side. This optical
element, however, provides no or little effect of attenuating the
power of reflection light, and thus is insufficient in restraining
unwanted light occurring in the imaging lens.
[0011] In an attempt to attenuate the power of reflection light,
the imaging lens recited in patent document 2 has an embossed layer
to scatter light on the outer surface of the imaging lens, in
addition to having the configuration of the optical element recited
in patent document 1. However, the mere formation of an embossed
layer is insufficient for restraining unwanted light, which does
not contribute to image formation.
[0012] The present invention has been made in light of the
above-described circumstances, and has an object to sufficiently
restrain unwanted light, which does not contribute to image
formation, by providing the outer circumference surface of an
optical element with a shape that sufficiently restrains reflection
light. The present invention also has an object to provide an
imaging lens using the optical element.
SUMMARY OF THE INVENTION
[0013] In order to accomplish the above-described object, an
optical element according to an embodiment of the present invention
includes an optical effective portion and an edge. The edge is
located around the optical effective portion and has an outer
circumference surface. The outer circumference surface includes a
roughened portion.
[0014] In order to accomplish the above-described object, an
imaging lens according to an embodiment of the present invention
includes optical element having the following configuration. The
optical element includes an optical effective portion and an edge.
The edge is located around the optical effective portion and has an
outer circumference surface. The outer circumference surface
includes a plurality of roughened portions.
Effects of the Invention
[0015] The embodiments of the present invention ensure that when
light in the optical element becomes incident on and reflected by
the outer circumference surface, the plurality of roughened
portions attenuate the power of the light sufficiently for
restraining ghosting and flare.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] A more complete appreciation of the present invention and
many of the attendant advantages thereof will be readily obtained
as the same becomes better understood by reference to the following
detailed description when considered in connection with the
accompanying drawings, wherein:
[0017] FIG. 1 is a schematic illustrating an optical element
according to an embodiment of the present invention;
[0018] FIG. 2 is a cross-sectional view of the optical element
according to the embodiment of the present invention;
[0019] FIG. 3 is a schematic illustrating a behavior of unwanted
light on roughened portions of an outer circumference surface of
the optical element;
[0020] FIG. 4 is an enlarged view of part (103) illustrated in FIG.
1, illustrating one embodiment of the roughened portion;
[0021] FIG. 5 is a cross-sectional view of one embodiment of an
imaging lens structure to which the optical element according to
the embodiment of the present invention is applied;
[0022] FIG. 6A illustrates unwanted light occurring in a
conventional imaging lens, and FIG. 6B illustrates unwanted light
occurring in the embodiment illustrated in FIG. 5, in which the
optical element according to the embodiment of the present
invention is applied to an imaging lens; and
[0023] FIG. 7A illustrates unwanted light occurring in a
conventional imaging lens, and FIG. 7B illustrates unwanted light
occurring in the embodiment illustrated in FIG. 5, in which the
optical element according to the embodiment of the present
invention is applied to an imaging lens.
[0024] In the optical element according to the embodiment of the
present invention, the outer circumference surface of the edge
formed around the optical effective portion of the optical element
includes a roughened portion. The roughened portion attenuates
unwanted light reflected by the outer circumference surface of the
optical element.
[0025] The embodiments of the present invention will be described
in detail below by referring to FIGS. 1 to 7.
[0026] FIG. 1 illustrates the optical element according to one
embodiment of the present invention.
[0027] As illustrated in FIG. 1, an optical element 100 includes an
optical effective portion 101 and an edge 102. The optical
effective portion 101 is where effective rays of light enter. The
edge 102 is formed around the optical effective portion 101 and
integral to the optical effective portion 101. The edge 102 has an
outer circumference surface 103. The outer circumference surface
103 includes a plurality of roughened portions 200.
[0028] FIG. 2 is a cross-sectional view of the optical element 100
taken along A-A' illustrated in FIG. 1.
[0029] As illustrated in FIG. 2, the roughened portions 200 of the
outer circumference surface 103 extend in parallel to the direction
in which the optical axis, X, of the optical element 100 extends.
It is to be noted that the roughened portions 200 may extend with
an angle relative to the optical axis X.
[0030] FIG. 3 illustrates a behavior of a ray of light SL incident
on the roughened portions 200 of the outer circumference surface
103.
[0031] As illustrated in FIG. 3, when the ray of light SL becomes
incident on the roughened portions 200 of the outer circumference
surface 103, the ray of light SL turns into scattered light with
attenuated light power.
[0032] Details of the shape of each roughened portion 200 may be
set using ghosting simulation software to form a shape that highly
accurately controls the directions in which the ray of light SL is
reflected. That is, an analysis for restraining ghosting and flare
can be performed at the design stage.
[0033] This eliminates or minimizes the need for the conventional
trial-and-error type of procedure that involves: evaluating the
occurrence of ghosting and flare after an imaging lens has been
assembled; analyzing the ghosting and flare for the cause of the
ghosting and flare; and feeding the analysis back to the design
stage.
[0034] Also, forming a roughened shape to scatter light is more
effective for restraining ghosting and flare than the mere
formation of an embossed layer.
[0035] It is preferable, therefore, to form an embossed layer on
the surfaces of the roughened portions 200 of the outer
circumference surface 103.
[0036] FIG. 4 illustrates one embodiment of a shape of the
roughened portion 200. In this embodiment, the roughened portion
200 has a height H of 0.065 mm; an edge portion E1 of an arcuate
protrusion of the roughened portion 200 has a radius (R) of R 0.05
mm; and an edge portion E2 of an arcuate depression of the
roughened portion 200 has a radius (R) of R 0.15 mm. The roughened
portion 200 thus dimensioned has a unit shape made up of a
protrusion and a depression, and a repetition of 72 unit shapes is
formed over the entire circumference of the outer circumference
surface of the edge (at a pitch P of 5.degree. (degrees) relative
to the optical axis X).
[0037] It is to be noted that the shape of the roughened portion
200 will not be limited to the above-described dimension values.
The roughened portion 200 may have any other shape insofar as,
preferably, the height H is equal to or more than 0.01 mm, the edge
portion E1 of the protrusion of roughened portion 200 has a radius
(R) of equal to or more than 0.03 mm, and the edge portion E2 of
the depression of roughened portion 200 has a radius (R) of equal
to or more than 0.03 mm. Also, the roughened portions 200 may be
formed partially on the outer circumference surface of the edge,
that is, at necessary portions of the outer circumference surface
of the edge such that the repetition of the protrusion-depression
unit shapes is equal to or more than ten (the pitch P is equal to
or less than 36.degree. (degrees) relative to the optical axis
X).
[0038] FIG. 5 illustrates one embodiment in which the optical
element 100 is applied to an imaging lens 300, which is made up of
six optical elements. In this embodiment, the optical element 100
is applied to one of the six optical elements.
[0039] As illustrated in FIG. 5, the imaging lens 300 includes a
barrel 302, a first lens L1, a second lens L2, a third lens L3, a
fourth lens L4, a fifth lens L5, a sixth lens L6, and a rear
light-shielding ring 304. The first lens L1, the second lens L2,
the third lens L3, the fourth lens L4, the fifth lens L5, the sixth
lens L6, and the rear light-shielding ring 304 are contained in the
barrel 302 in this order from the object side (from the upper side
of FIG. 5) toward the side of imaging element IMG (toward the lower
side of FIG. 5).
[0040] A light shielding plate 303 is located between the first
lens L1 and the second lens L2; a light shielding plate 303 is
located between the second lens L2 and the third lens L3; a light
shielding plate 303 is located between the third lens L3 and the
fourth lens L4; a light shielding plate 303 is located between the
fourth lens L4 and the fifth lens L5; and a light shielding plate
303 is located between the fifth lens L5 and the sixth lens L6.
[0041] The rear light-shielding ring 304 is a member that fixes the
first to sixth lenses L1 to L6 in the optical axis X direction and
that is fixed by welding to the inner surface of the barrel 302
using a solvent such as methyl acetate. It is to be noted that the
method of fixing the rear light-shielding ring 304 to the barrel
302 will not be limited to welding, other examples including
bonding, press fitting, and a combination of the foregoing.
[0042] Also, the material of the lens constituting each of the
optical elements is an optical-purpose resin such as cycloolefin
polymer and polycarbonate. Also, the optical elements are formed by
injection molding.
[0043] The imaging lens 300 is applicable to, for example,
small-size imaging lenses used in mobile phones and smartphones. A
filter IR to cut infrared light is disposed at the imaging element
IMG side of the imaging lens 300. Next to the filter IR, the
imaging element IMG is disposed. Examples of the imaging element
IMG include, but are not limited to, a CCD sensor and a C-MOS
sensor. Thus, the imaging lens 300, the filter IR, and the imaging
element IMG are packaged into a camera module.
[0044] Each of the lenses has an optical effective portion (lens
portion) and an edge formed around the optical effective portion.
The edge of each lens has a protrusion engaged with an adjacent
lens. The protrusion has an approximately trapezoid shape that
includes a conical inclined surface and a plane portion connected
to the inclined surface.
[0045] Next, how the imaging lens 300 is structured will be
described.
[0046] A plane portion L1a of the edge of the first lens L1 is
brought into contact with a receiving surface 302a. The receiving
surface 302a is formed on the inner surface of the barrel 302 and
is perpendicular to the optical axis X. In this manner, the
position of the first lens L1 in the optical axis X direction is
determined.
[0047] Also, an outer surface L1c of the first lens L1 is brought
into engagement with an inner diameter portion 302b of the barrel
302. In this manner, the first lens L1 and the barrel 302 are
subjected to axis alignment such that the first lens L1 and the
barrel 302 are aligned with each other on the optical axis X.
[0048] Next, an inclined surface L1b of the first lens L1 is
brought into engagement with an inclined surface L2a of the second
lens L2. In this manner, the first lens L1 and the second lens L2
are subjected to axis alignment such that the first lens L1 and the
second lens L2 are aligned with each other on the optical axis
X.
[0049] Next, an inclined surface L2b of the second lens L2 is
brought into engagement with an inclined surface L3a of the third
lens L3. In this manner, the second lens L2 and the third lens L3
are subjected to axis alignment such that the second lens L2 and
the third lens L3 are aligned with each other on the optical axis
X.
[0050] Next, an inclined surface L3b of the third lens L3 is
brought into engagement with an inclined surface L4a of the fourth
lens L4. In this manner, the third lens L3 and the fourth lens L4
are subjected to axis alignment such that the third lens L3 and the
fourth lens L4 are aligned with each other on the optical axis
X.
[0051] Next, an inclined surface 5b of the fifth lens L5 is brought
into engagement with an inclined surface L 6a of the sixth lens L6.
In this manner, the fifth lens L5 and the sixth lens L6 are
subjected to axis alignment such that the fifth lens L5 and the
sixth lens L6 are aligned with each other on the optical axis
X.
[0052] Next, an outer surface L6c of the sixth lens L6 is brought
into engagement with an inner diameter portion 302c of the barrel
302. In this manner, the sixth lens L6 and the barrel 302 are
subjected to axis alignment such that the sixth lens L6 and the
barrel 302 are aligned with each other on the optical axis X.
[0053] In the above-described structure of the imaging lens 300, a
lens assembly 301 results with such a structure that the centers of
the first to sixth lenses L1 to L6 are aligned with each other on
the optical axis X and that the center of the barrel 302 is aligned
with the centers of the first to sixth lenses L1 to L6 on the
optical axis X.
[0054] Also in the above-described structure of the imaging lens
300, the first to fourth lenses L1 to L4 and the fifth and sixth
lenses L5 and L6 each have a protrusion at the edge of each lens.
The protrusion includes an inclined surface and a plane portion
connected to the inclined surface. The plane portion is in contact
with the plane portion of the edge of an adjacent lens. The contact
between the plane portions determines the gap between one lens and
an adjacent lens. It is to be noted that the gap between the fourth
lens L4 and the fifth lens L5 is determined by the thickness of the
light shielding plate 303.
[0055] Thus, the centers of the lenses of the lens assembly 301 are
brought into alignment with each other on the optical axis X by the
mere superposition of the lenses on top of each other. At the same
time, the superposition of the lenses on top of each other
determines the gaps between the lenses.
[0056] It is to be noted that the light shielding plate 303 located
between one lens and an adjacent lens is a flat annular light
shielding member with an opening at the center of the annular light
shielding member.
[0057] The diameter of the opening of the light shielding plate 303
is set at a minimum possible diameter that does not obstruct
passage of a light flux B0 and a light flux B1. The light flux B0
is a flux of effective rays of light that become incident on the
imaging lens 300 and collect on the optical axis X. The light flux
B1 is a flux of effective rays of light incident that become
incident on the imaging lens 300 from a maximum field angle and
that collect to a maximum image height. Rays of light incident from
positions outer than the light flux B1 are blocked by the light
shielding plate 303. Thus, the light shielding plate 303 blocks
unwanted light while permitting effective rays of light to pass
through the light shielding plate 303.
[0058] FIG. 5 illustrates an embodiment in which the optical
element 100 is applied to the fifth lens L5 among the first to
sixth lenses L1 to L6 of the imaging lens 300.
[0059] Next, by referring to the embodiment illustrated in FIG. 5,
description will be made with regard to how the optical element 100
attenuates the power of reflection light that can cause ghosting
and flare.
[0060] FIG. 6A is a schematic illustrating a state in which
unwanted light is occurring in a conventional imaging lens 300',
and FIG. 6B is a schematic illustrating a state in which the
imaging lens 300 illustrated in FIG. 5 restrains unwanted
light.
[0061] As illustrated in FIG. 6A, the ray of light SL passes
through the imaging lens 300'; is reflected by the upper surface of
the filter IR; enters the edge of the sixth lens L6; passes through
the portion of engagement between the sixth lens L6 and the fifth
lens L5; is reflected by the outer surface of the fifth lens L5; is
totally reflected by the effective diameter portion of the fifth
lens L5; passes through the filter IR; and reaches the imaging
element IMG.
[0062] The ray of light SL reaching the imaging element IMG appears
in the photographed image in the form of ghosting and/or flare, to
the detriment of image quality.
[0063] FIG. 6B illustrates an example in which the optical element
100 (according to the above-described embodiment of the present
invention) is applied to the fifth lens L5 of the imaging lens 300'
illustrated in FIG. 6A. Specifically, the roughened portions 200
are formed on the outer circumference surface 103 of the fifth lens
L5 of the imaging lens 300'.
[0064] As illustrated in FIG. 6B, the ray of light SL passes
through the imaging lens 300; is reflected by the upper surface of
the filter IR; enters the edge of the sixth lens L6; passes through
the portion of engagement between the sixth lens L6 and the fifth
lens L5; becomes incident on the outer surface of 103 of the fifth
lens L5; and is scattered by the roughened portions 200 of the
outer circumference surface 103. This attenuates the power of the
light incident on and reflected by the outer surface of the fifth
lens L5.
[0065] Thus, the ray of light SL scattered by the roughened
portions 200 of the outer surface of the fifth lens L5 has been
attenuated in light power. This prevents the ray of light SL from
being totally reflected by the effective diameter portion of the
fifth lens L5 and reaching the imaging element IMG through the
filter IR. This effectively restrains occurrence of ghosting and
flare.
[0066] FIG. 7A is a schematic illustrating a state in which
unwanted light is occurring in the conventional imaging lens 300',
and FIG. 7B is a schematic illustrating a state in which the
imaging lens 300 illustrated in FIG. 5 restrains unwanted
light.
[0067] As illustrated in FIG. 7A, unwanted light SL is reflected by
a surface of the edge of the fifth lens L5 of the imaging lens
300'; is reflected by the outer circumference surface 103 of the
fifth lens L5; is totally reflected by the effective diameter
portion of the fifth lens L5; passes through the filter IR; and
reaches the imaging element IMG. The ray of light SL reaching the
imaging element IMG appears in the photographed image in the form
of ghosting and/or flare, to the detriment of image quality.
[0068] FIG. 7B illustrates an example in which the optical element
100 (according to the above-described embodiment of the present
invention) is applied to the fifth lens L5 of the imaging lens 300'
illustrated in FIG. 7A. Specifically, the roughened portions 200
are formed on the outer circumference surface 103 of the fifth lens
L5 of the imaging lens 300'.
[0069] As illustrated in FIG. 7B, the unwanted light SL is
reflected by a surface of the edge of the fifth lens L5 of the
imaging lens 300; becomes incident on the outer circumference
surface 103 of the fifth lens L5; and is scattered by the roughened
portions 200 of the outer circumference surface 103. This
attenuates the power of the light incident on and reflected by the
outer surface of the fifth lens L5.
[0070] Thus, the unwanted light SL scattered by the roughened
portions 200 of the outer surface of the fifth lens L5 has been
attenuated in light power. This prevents the unwanted light SL from
being totally reflected by the effective diameter portion of the
fifth lens L5 and reaching the imaging element IMG through the
filter IR. This effectively restrains occurrence of ghosting and
flare.
[0071] As has been described hereinbefore, in the optical element
according to the embodiment of the present invention and in the
imaging lens using the optical element, roughened portions to
restrain unwanted light are formed on the outer surface of the edge
around the optical effective portion. This effectively restrains
occurrence of ghosting and flare.
[0072] In the above description, the optical element according to
the embodiment of the present invention is applied to the fifth
lens of an imaging lens made up of six lenses. This configuration,
however, is not intended in a limiting sense; the optical element
may be applied to any other portion of an imaging lens where it is
necessary to restrain light reflection on the outer circumference
of the optical element. It is also possible to apply the optical
element according to the embodiment of the present invention to a
plurality of lenses of an imaging lens, or to an imaging lens made
up of a single optical element.
[0073] Obviously, numerous modifications and variations of the
present invention are possible in light of the above teachings. It
is therefore to be understood that within the scope of the appended
claims, the present invention may be practiced otherwise than as
specifically described herein.
INDUSTRIAL APPLICABILITY
[0074] The embodiments of the present invention effectively
restrain light reflection in optical elements, and, when applied to
imaging devices requiring high image quality, contribute to
improvement of optical performance and quality of the imaging
devices.
DESCRIPTION OF REFERENCE NUMERAL
[0075] 100 Optical element [0076] 101 Optical effective portion
(lens portion) [0077] 102 Edge [0078] 103 Outer circumference
surface [0079] 200 Roughened portion [0080] 300, 300' Imaging lens
[0081] 301 Lens assembly [0082] 302 Barrel [0083] 303 Light
shielding plate [0084] 304 Rear light-shielding ring [0085] L1
First lens [0086] L2 Second lens [0087] L3 Third lens [0088] L4
Fourth lens [0089] L5 Fifth lens [0090] L6 Sixth lens [0091] L1b,
L2a, L2b, L3a, L3b, L4a, L5b, L6a Lens engagement portion [0092]
L1a, L1c, L6c, 302a, 302b, 303c Barrel engagement portion [0093] B0
Effective light flux on optical axis [0094] B1 Effective light flux
at maximum image height [0095] SL Ray of light, unwanted light
[0096] X Optical axis [0097] IR Filter [0098] IMG Imaging
device
* * * * *