U.S. patent application number 16/160987 was filed with the patent office on 2019-12-19 for lens assembly.
This patent application is currently assigned to Rays Optics Inc.. The applicant listed for this patent is Rays Optics Inc.. Invention is credited to Hung-You CHENG, Ying-Hsiu LIN, Kuo-Chuan WANG.
Application Number | 20190384042 16/160987 |
Document ID | / |
Family ID | 68839919 |
Filed Date | 2019-12-19 |
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United States Patent
Application |
20190384042 |
Kind Code |
A1 |
LIN; Ying-Hsiu ; et
al. |
December 19, 2019 |
LENS ASSEMBLY
Abstract
A lens assembly including 4.about.7 lenses with a refractive
power is provided. D1 is the diameter of a lens surface farthest
away from the image plane of the lens assembly. DL is the diameter
of a lens surface closest to the image plane of the lens assembly.
LT is the length on an optical axis of the lens from the lens
surface farthest away from the image plane of the lens assembly to
the lens surface closest to the image plane of the lens assembly.
The lens assembly satisfies the following conditions: (1) 6
mm<DL<20 mm, 1.5<LT/DL<2.4 and D1/DL>0.6 or (2) 6
mm<DL<20 mm, 1.25<LT/DL<1.7 and D1/DL>0.4.
Inventors: |
LIN; Ying-Hsiu; (Hsinchu
City, TW) ; CHENG; Hung-You; (Hsinchu City, TW)
; WANG; Kuo-Chuan; (Hsinchu City, TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Rays Optics Inc. |
Hsinchu County |
|
TW |
|
|
Assignee: |
Rays Optics Inc.
Hsinchu County
TW
|
Family ID: |
68839919 |
Appl. No.: |
16/160987 |
Filed: |
October 15, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G02B 13/006 20130101;
G02B 9/60 20130101; G02B 13/0045 20130101; G02B 9/62 20130101; G02B
9/64 20130101; G02B 13/18 20130101 |
International
Class: |
G02B 13/18 20060101
G02B013/18 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 15, 2018 |
TW |
107120644 |
Claims
1. A lens assembly, comprising: more than 3 but less than 8 lenses
with a refractive power, wherein D1 is the distance between two
turning points on a lens surface farthest away from the image plane
of the lens assembly; DL is the distance between two turning points
on a lens surface closest to the image plane of the lens assembly;
LT is the length on an optical axis of the lens from the lens
surface farthest from the image plane of the lens assembly to the
lens surface closest to the image plane of the lens assembly;
wherein the lens assembly satisfies the following conditions: 6
mm<DL<20 mm, 1.5<LT/DL<2.4 and D1/DL>0.6 or (1) 6
mm<DL<20 mm, 1.25<LT/DL<1.7 and D1/DL>0.4. (2)
2. The lens assembly according to claim 1, wherein the aperture
value (F/#) of the lens is greater than or equivalent to 2.6.
3. The lens assembly according to claim 1, wherein the lens
assembly comprises at least two lenses whose Abbe numbers are
greater than 58.
4. The lens assembly according to claim 1, wherein the total length
of the lens assembly (LT) is less than 25 mm.
5. The lens assembly according to claim 1, wherein the lens
assembly satisfies one of the following conditions: (1) the lenses
arranged from the image magnification side to the image reduction
side sequentially are concave-convex lens, convex-concave lens,
concave-convex lens, bi-concave lens, bi-convex lens and aspheric
lens; (2) the lenses arranged from the image magnification side to
the image reduction side sequentially are concave-convex lens,
convex-concave lens, bi-concave lens, bi-convex lens and the
aspheric lens; (3) the lenses arranged from the image magnification
side to the image reduction side sequentially are plano-convex
lens, bi-convex lens, bi-concave lens, bi-convex lens and aspheric
lens; (4) the lenses arranged from the image magnification side to
the image reduction side sequentially are concave-convex lens,
bi-concave lens, concave-convex lens, bi-convex lens and aspheric
lens; (5) the lenses arranged from the image magnification side to
the image reduction side sequentially are bi-concave lens,
bi-convex lens, plano-convex lens, bi-concave lens, bi-convex lens,
bi-convex lens and convex-concave lens.
6. The lens assembly according to claim 1, wherein the lens
assembly satisfies one of the following conditions: (1) the
refractive powers of the lenses arranged from the image
magnification side to the image reduction side sequentially are
positive, negative, positive, negative, positive, positive; (2) the
refractive powers of the lenses arranged from the image
magnification side to the image reduction side sequentially are
positive, negative, negative, positive, positive; (3) the
refractive powers of the lenses arranged from the image
magnification side to the image reduction side sequentially are
positive, positive, negative, positive, negative; (4) the
refractive powers of the lenses arranged from the image
magnification side to the image reduction side sequentially are
positive, negative, positive, positive, negative; (5) the
refractive powers of the lenses arranged from the image
magnification side to the image reduction side sequentially are
negative, positive, positive, negative, positive, positive,
negative.
7. A lens assembly, comprising: a combined lens, wherein the
combined lens is formed of two lenses and comprises corresponding
adjacent surfaces whose radii of curvature are substantially
identical; and a spherical lens and an aspheric lens, wherein the
quantity of the lenses with a refractive power is less than 8; the
aspheric lens is closer to the image plane of the lens assembly
than the combined lens; at most one lens is disposed between the
aspheric lens and the image plane of the lens assembly; DFOV is the
diagonal field of view of the lens; DL the distance between two
turning points on a lens surface closest to the image plane of the
lens assembly; LT is the length on an optical axis of the lens from
a lens surface farthest away from the image plane of the lens
assembly to the lens surface closest to the image plane of the lens
assembly; the lens assembly satisfies the following conditions:
40.degree.<DFOV<60.degree., 6 mm<DL<20 mm,
1.5<LT/DL<2.4.
8. The lens assembly according to claim 7, wherein the lens
assembly satisfies one of the following conditions: (1) the lens
assembly further comprises an aperture, and the aspheric lens is
disposed between the image reduction side and the aperture; (2) the
lens further comprises an aperture, the combined lens is disposed
between the image reduction side and the aperture, and the
difference in the radius of curvature between two adjacent surfaces
of the combined lens is less than 0.005 mm; (3) all lenses are
formed of glass.
9. The lens assembly according to claim 7, wherein the aperture
value (F/#) of the lens is greater than or equivalent to 2.6.
10. The lens assembly according to claim 7, wherein the lens
assembly comprises at least two lenses whose Abbe numbers are
greater than 58.
11. The lens assembly according to claim 7, wherein the total
length of the lens assembly (LT) is less than 25 mm.
12. The lens assembly according to claim 7, wherein the lens
assembly satisfies one of the following conditions: (1) the lenses
arranged from the image magnification side to the image reduction
side sequentially are concave-convex lens, convex-concave lens,
concave-convex lens, bi-concave lens, bi-convex lens and aspheric
lens; (2) the lenses arranged from the image magnification side to
the image reduction side sequentially are concave-convex lens,
convex-concave lens, bi-concave lens, bi-convex lens and the
aspheric lens; (3) the lenses arranged from the image magnification
side to the image reduction side sequentially are plano-convex
lens, bi-convex lens, bi-concave lens, bi-convex lens and aspheric
lens; (4) the lenses arranged from the image magnification side to
the image reduction side sequentially are concave-convex lens,
bi-concave lens, concave-convex lens, bi-convex lens and aspheric
lens; (5) the lenses arranged from the image magnification side to
the image reduction side sequentially are bi-concave lens,
bi-convex lens, plano-convex lens, bi-concave lens, bi-convex lens,
bi-convex lens and convex-concave lens.
13. The lens assembly according to claim 7, wherein the lens
assembly satisfies one of the following conditions: (1) the
refractive powers of the lenses arranged from the image
magnification side to the image reduction side sequentially are
positive, negative, positive, negative, positive, positive; (2) the
refractive powers of the lenses arranged from the image
magnification side to the image reduction side sequentially are
positive, negative, negative, positive, positive; (3) the
refractive powers of the lenses arranged from the image
magnification side to the image reduction side sequentially are
positive, positive, negative, positive, negative; (4) the
refractive powers of the lenses arranged from the image
magnification side to the image reduction side sequentially are
positive, negative, positive, positive, negative; (5) the
refractive powers of the lenses arranged from the image
magnification side to the image reduction side sequentially are
negative, positive, positive, negative, positive, positive,
negative.
14. A lens assembly, comprising: a combined lens, wherein the
combined lens is formed of two lenses and comprises corresponding
adjacent surfaces whose radii of curvature are substantially
identical; and a spherical lens and an aspheric lens, wherein the
quantity of the lenses with a refractive power is less than 8; the
aspheric lens is closer to the image plane of the lens assembly
than the combined lens; at most one lens is disposed between the
aspheric lens and the image plane of the lens assembly; the Abbe
number of at least one lens of the combined lens and the Abbe
number of the aspheric lens both are greater than 60; the surface
of the aspheric lens facing the image plane of the lens assembly on
the lens optical path is protruded towards the image plane of the
lens assembly.
15. The lens assembly according to claim 14, wherein the lens
assembly satisfies one of the following conditions: (1) the lens
assembly further comprises an aperture, and the aspheric lens is
disposed between the image reduction side and the aperture; (2) the
lens further comprises an aperture, the combined lens is disposed
between the image reduction side and the aperture, and the
difference in the radius of curvature between two adjacent surfaces
of the combined lens is less than 0.005 mm; (3) all lenses are
formed of glass.
16. The lens assembly according to claim 14, wherein the aperture
value (F/#) of the lens is greater than or equivalent to 2.6.
17. The lens assembly according to claim 14, wherein the lens
assembly comprises at least two lenses whose Abbe numbers are
greater than 58.
18. The lens assembly according to claim 14, wherein the total
length of the lens assembly (LT) is less than 25 mm.
19. The lens assembly according to claim 14, wherein the lens
assembly satisfies one of the following conditions: (1) the lenses
arranged from the image magnification side to the image reduction
side sequentially are concave-convex lens, convex-concave lens,
concave-convex lens, bi-concave lens, bi-convex lens and aspheric
lens; (2) the lenses arranged from the image magnification side to
the image reduction side sequentially are concave-convex lens,
convex-concave lens, bi-concave lens, bi-convex lens and the
aspheric lens; (3) the lenses arranged from the image magnification
side to the image reduction side sequentially are plano-convex
lens, bi-convex lens, bi-concave lens, bi-convex lens and aspheric
lens; (4) the lenses arranged from the image magnification side to
the image reduction side sequentially are concave-convex lens,
bi-concave lens, concave-convex lens, bi-convex lens and aspheric
lens; (5) the lenses arranged from the image magnification side to
the image reduction side sequentially are bi-concave lens,
bi-convex lens, plano-convex lens, bi-concave lens, bi-convex lens,
bi-convex lens and convex-concave lens.
20. The lens assembly according to claim 14, wherein the lens
assembly satisfies one of the following conditions: (1) the
refractive powers of the lenses arranged from the image
magnification side to the image reduction side sequentially are
positive, negative, positive, negative, positive, positive; (2) the
refractive powers of the lenses arranged from the image
magnification side to the image reduction side sequentially are
positive, negative, negative, positive, positive; (3) the
refractive powers of the lenses arranged from the image
magnification side to the image reduction side sequentially are
positive, positive, negative, positive, negative; (4) the
refractive powers of the lenses arranged from the image
magnification side to the image reduction side sequentially are
positive, negative, positive, positive, negative; (5) the
refractive powers of the lenses arranged from the image
magnification side to the image reduction side sequentially are
negative, positive, positive, negative, positive, positive,
negative.
Description
[0001] This application claims the benefit of Taiwan application
Serial No. 107120644, filed Jun. 15, 2018, the subject matter of
which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
Field of the Invention
[0002] The invention relates in general to a lens assembly.
Description of the Related Art
[0003] Along with the development in technology, the variety of
lenses is getting more and more diversified. The lens used in
vehicles is a commonly seen lens. Currently, higher and higher
requirements, such as thinness and better optical features, are
expected of the lens. To satisfy the said requirements, the lens
basically needs to possess the features of lower cost, higher
resolution, larger aperture, larger target surface and lighter
weight. Therefore, it has become a prominent task for the
industries to provide an image lens having the features of lighter
weight, lower manufacturing cost, and better optical quality.
[0004] The description of related art is provided to facilitate the
understanding of the present invention. Therefore, the contents
disclosed in the related art may include some technologies not
generally known to anyone ordinarily skilled in the technology
field of the present invention. The contents disclosed in the
related art and the problems that one or more than one embodiment
of the present invention aims to resolve are not necessarily known
to or acknowledged by anyone ordinarily skilled in the technology
field of the present invention before the application of the
present invention is filed.
SUMMARY OF THE INVENTION
[0005] Other objects and advantages of the present invention can be
understood from the technical features disclosed in the embodiments
of the present invention.
[0006] According to one embodiment of the present invention, a lens
assembly including 4.about.7 lenses with a refractive power is
provided. D1 is the diameter of a lens surface farthest away from
the image plane of the lens assembly. DL is the diameter of a lens
surface closest to the image plane of the lens assembly. LT is the
length on an optical axis of the lens from the lens surface
farthest away from the image plane of the lens assembly to the lens
surface closest to the image plane of the lens assembly. The lens
assembly satisfies the following conditions: (1) 6 mm<DL<20
mm, 1.5<LT/DL<2.4 and D1/DL>0.6 or (2) 6 mm<DL<20
mm, 1.25<LT/DL<1.7 and D1/DL>0.4. In the present
embodiment, the lens includes 4.about.7 lenses which can be divided
into a front lens group and a rear lens group. The rear lens group
includes an aspheric lens. Thus, an image lens having the features
of lighter weight, lower manufacturing cost, large target surface
and better optical quality can be achieved.
[0007] According to another embodiment of the present invention, a
lens assembly including a combined lens, a spherical lens and an
aspheric lens is provided. The combined lens is formed of two
lenses and includes corresponding adjacent surfaces whose radii of
curvature are substantially identical. The aspheric lens is closer
to the image plane of the lens assembly than the combined lens. At
most one lens is disposed between the aspheric lens and the image
plane of the lens assembly. The lens includes 4.about.7 lenses with
a refractive power. DFOV is the diagonal field of view of the lens.
DL is the diameter of a lens surface closest to the image plane of
the lens assembly. LT is the length on an optical axis of the lens
from a lens surface farthest away from the image plane of the lens
assembly to the lens surface closest to the image plane of the lens
assembly. The lens assembly satisfies the following conditions:
40.degree.<DFOV<60.degree., 6 mm<DL<20 mm,
1.5<LT/DL<2.4. In the present embodiment, the lens includes
4.about.7 lenses including a spherical lens, a combined lens and an
aspheric lens. Thus, an image lens having the features of lighter
weight, lower manufacturing cost, longer focal length, large target
surface and better optical quality can be achieved.
[0008] According to an alternate embodiment of the present
invention, a lens assembly including a combined lens, a spherical
lens and an aspheric lens is provided. The combined lens is formed
of two lenses and includes corresponding adjacent surfaces whose
radii of curvature are substantially identical. The aspheric lens
is closer to the image plane of the lens assembly than the combined
lens. At most one lens is disposed between the aspheric lens and
the image plane of the lens assembly. The lens includes 4.about.7
lenses with a refractive power. The Abbe number of at least one
lens of the combined lens and the Abbe number of the aspheric lens
both are greater than 60. The surface of the aspheric lens facing
the image plane of the lens assembly on the lens optical path is
protruded towards the image plane of the lens assembly. In the
present embodiment, the lens includes 4.about.7 lenses including a
spherical lens, a combined lens and an aspheric lens. Thus, an
image lens having the features of lighter weight, lower
manufacturing cost, longer focal length, large target surface and
better optical quality can be achieved.
[0009] Through the design disclosed in the embodiments of the
present invention, an image lens possessing the optical features of
excellent optical quality and light weight and capable of reducing
manufacturing cost and improving optical quality is provided. Based
on the design that the optical lens includes 4.about.7 lenses and
that the total track length (TTL) from the lens to the sensor is
less than 25 mm and the maximum outer diameter of the mechanism is
less than 14 mm, the optical lens assembly advantageously possesses
the features of larger aperture, higher resolution (5 million
pixels), lighter weight, longer effective focal length (EFL=12 mm),
and larger target surface (1/2.5 inch), the manufacturing cost can
be reduced and the optical quality can be improved.
[0010] The above and other aspects of the invention will become
better understood with regard to the following detailed description
of the preferred but non-limiting embodiment (s). The following
description is made with reference to the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a schematic diagram of a lens assembly 10a
according to a first embodiment of the present invention.
[0012] FIGS. 2.about.3 respectively are a ray fan plot and a
longitudinal aberration graph of the lens assembly 10a.
[0013] FIG. 4 is a schematic diagram of a lens assembly 10b
according to a second embodiment of the present invention.
[0014] FIGS. 5.about.6 respectively are a ray fan plot and a
longitudinal aberration graph of the lens assembly 10b.
[0015] FIG. 7 is a schematic diagram of a lens assembly 10c
according to a third embodiment of the present invention.
[0016] FIGS. 8.about.9 respectively are a ray fan plot and a
longitudinal aberration graph of the lens assembly 10c.
[0017] FIG. 10 is a schematic diagram of a lens assembly 10d
according to a fourth embodiment of the present invention.
[0018] FIGS. 11.about.12 respectively are a ray fan plot and a
longitudinal aberration graph of the lens assembly 10d.
[0019] FIG. 13 is a schematic diagram of a lens assembly 10e
according to a fifth embodiment of the present invention.
[0020] FIGS. 14.about.15 respectively are a ray fan plot and a
longitudinal aberration graph of the lens assembly 10e.
[0021] FIG. 16 is a schematic diagram of a lens assembly 10f
according to a sixth embodiment of the present invention.
[0022] FIGS. 17.about.18 respectively are a ray fan plot and a
longitudinal aberration graph of the lens assembly 10f.
DETAILED DESCRIPTION OF THE INVENTION
[0023] The technical contents, features, and effects of the present
invention are disclosed below in a number of embodiments with
accompanying drawings. Directional terms such as above, under,
left, right, front or back are used in the following embodiments to
indicate the directions of the accompanying drawings, not for
limiting the present invention. Moreover, ordinal numbers, such as
"the first" and "the second", are used in the following embodiments
to clearly distinguish the elements having the same designations,
not for limiting the said element.
[0024] The optical elements in the present invention refer to the
elements partly or completely of reflective or transmissive
materials normally including glass or plastics. Examples of the
optical elements include lens, prism or aperture.
[0025] When the lens is used in an imaging system, the image
magnification side (object side, the first side) refers to the side
of the lens assembly closer to the object to be shot on the optical
path, and the image reduction side (imaging side, the second side)
refers to the side of the lens assembly closer to the sensor on the
optical path.
[0026] When the image magnification side (or the image reduction
side) of a lens has a convex portion (or a concave portion) at a
particular area, this implies that the said area is more protruded
(or recessed) towards a direction parallel to the optical path than
outer area adjacent to the said area.
[0027] FIG. 1 is a schematic diagram of a lens assembly 10a
according to a first embodiment of the present invention. Refer to
FIG. 1. In the present embodiment, the lens assembly 10a includes a
lens barrel (not illustrated), within which a first lens L1, a
second lens L2, a third lens L3, an aperture 14 and a fourth lens
L4, a fifth lens L5 and a sixth lens L6 are arranged from the first
side (the image magnification side/object side/OS) to the second
side (the image reduction side/imaging side/IS). The first lens L1,
the second lens L2 and the third lens L3 form a first lens group
(such as a front group) 20 with a negative refractive power. The
fourth lens L4, the fifth lens L5 and the sixth lens L6 form a
second lens group (such as a rear lens group) 30 with a positive
refractive power. Moreover, a filter 16 and an image sensor (not
illustrated) are disposed on the image reduction side IS. The image
plane of the lens assembly 10a of a visible light at an effective
focal length is designated by 18. The filter 16 is disposed between
the second lens group 30 and the image plane 18 of the lens
assembly 10a of a visible light at an effective focal length. In
the present embodiment, the refractive powers of the first lens L1
to the sixth lens L6 sequentially are: positive (+), negative (-),
positive, negative, positive, positive, and the sixth lens is an
aspheric glass lens. In an embodiment, aspheric glass lenses can be
replaced by aspheric plastics lenses. Additionally, the lenses
whose adjacent surfaces have substantially identical radius of
curvature (the difference in the radius of curvature is less than
0.005 mm) or completely identical radius of curvature can form one
combined lens/glued lens/doublet lens/triplet lens. In the present
embodiment, the first lens L1 and the second lens L2 form one
combined lens, and the fourth lens L4 and the fifth lens L5 also
form the other combined lens, but the present invention are not
limited thereto. In each diagram of each embodiment of the present
invention, the image magnification side OS is located at the
left-hand side and the image reduction side IS is located at the
right-hand side, and the similarities are not repeated here.
[0028] In the present invention, the aperture 14 refers to an
aperture stop. The aperture is an independent element or is
integrated in other optical elements. In the present embodiment,
the aperture achieves a similar effect by blocking the light on the
peripheral part using a mechanism member but keeping the central
part permeable to the light. The said mechanism member can be
adjustable, which means the position, shape and transparency of the
mechanism member can be adjusted. Or, the aperture can limit the
optical path by coating an opaque light absorbing material on the
surface of the lens but keeping the central part permeable to the
light.
[0029] Each lens has a surface diameter. As indicated in FIG. 1,
the surface diameter of a lens refers to the distance (such as
surface diameter D), in a direction perpendicular to an optical
axis, between two edge turning points P and Q at the two ends of
the optical axis 12 of the lens. In the present embodiment, the
surface S1 has a diameter of 10 mm, and the surface S11 has a
diameter of 6.2 mm.
[0030] The design parameters, shapes and aspheric coefficients of
the lens assembly 10a are listed in Table 1 and Table 2. In a
design example of the present invention, the aspheric polynomial
can be expressed as:
Z = cr 2 1 + 1 - ( 1 + k ) c 2 r 2 + Ar 4 + Br 6 + Cr 8 + Dr 10 +
Er 12 + Fr 14 + ( 1 ) ##EQU00001##
[0031] In the formula (1), Z represents a sag along the direction
of the optical axis; c represents a reciprocal of the radius of an
osculating sphere, that is, the reciprocal of the radius of
curvature close to the optical axis; k represents a conic
coefficient; r represents an aspheric height, that is, the height
from the center to the edge of the lens. In Table 2, columns A-G
respectively represent the values of the coefficients of the
4.sup.th, the 6.sup.th, the 8.sup.th, the 10.sup.th, the 12.sup.th,
the 14.sup.th, and the 16.sup.th order terms of the spherical
polynomial. However, the data exemplified below are not for
limiting the present invention. Any person ordinary skilled in the
technology field can make necessary modifications or adjustments to
the parameters or setting of the present invention, and the said
modifications or adjustments are still within the scope of the
present invention.
TABLE-US-00001 TABLE 1 F/# = 2.65; TTL = 23.0 (mm) DFOV =
45.degree.; LT/DL = 2.112 D1/DL = 1.639; IMH = 5.15 (mm) Radius of
Interval Refractive Abbe Surface curvature (mm) (mm) power number
Element S1 6.18 3.26 1.95 32.32 L1 (concave- convex) S2 15.21 0.67
1.78 25.68 L2 (convex- concave) S3 2.94 1.67 S4 12.78 1.41 1.90
31.32 L3 (concave- convex) S5 38.87 0.63 S6 INF. 0.32 Aperture 14
S7 -13.21 0.50 1.55 45.78 L4 (bi-concave) S8 4.39 2.01 1.60 67.74
L5 (bi-convex) S9 -10.22 0.29 S10* -10.03 2.13 1.50 81.5 L6
(aspheric) S11* -4.03 8.53 S12 INF. 0.71 52.0 54.5 Filter 16 S13
INF. 0.83 S14 Image plane 18
TABLE-US-00002 TABLE 2 S10* S11* k 0 0 A -1.08E-03 7.70E-04 B
-8.60E-05 -9.03E-06 C 1.74E-06 3.71E-06 D 1.18E-06 -7.46E-08 E
-1.20E-07 2.08E-08
[0032] The interval of the surface S1 is the distance on the
optical axis 12 from the surface S1 to the surface S2. The interval
of the surface S2 is the distance on the optical axis 12 from the
surface S2 to the surface S3. The interval of the surface S13 is
the distance on the optical axis 12 from the surface S13 to the
image plane 18 of a visible light at an effective focal length.
[0033] In the tables, the surface with a * sign is an aspheric
surface, and the surface without the * sign is a spherical
surface.
[0034] The radius of curvature refers to the reciprocal of the
curvature. When the radius of curvature is positive, the sphere
center of the lens surface is located at the image reduction side
of the lens assembly. When the radius of curvature is negative, the
sphere center of the lens surface is located at the image
magnification side of the lens assembly. The concavity and
convexity of each lens are listed in above tables.
[0035] The aperture value of the present invention is represented
by F/# as indicated in above tables. When the lens of the present
invention is used in a projection system, the image plane is a
light valve surface. When the lens is used in an imaging system,
the image plane refers to the surface of the sensor.
[0036] When the lens is used in an imaging system, the image height
IMH is 1/2 of the length of the image circle on the image plane as
indicated in above tables.
[0037] In the present invention, the total length of the lens is
represented by LT as indicated in above tables. To be more
specifically, in the present embodiment, the total length refers to
the distance on the optical axis 12 of the lens assembly 10a from
the optical surface S1 closest to the image magnification side to
the optical surface S11 closest to the image reduction side. The
total length (LT) of the lens is less than 23 mm.
[0038] In the present embodiment, the diagonal field of view DFOV
refers to the receiving angle of the optical surface S1 closest to
the image magnification end, that is, the field of view measured
using the image circle as indicated in above tables.
[0039] FIGS. 2.about.3 are based on the simulation data of the lens
assembly 10a of the present embodiment. FIG. 2 is a ray fan plot of
a visible light, wherein X axis represents the position at which a
ray enters the pupil, Y axis represents a relative value of the
position at which the chief ray is projected to an image plane
(such as the image plane 18). FIG. 3 is a graph of longitudinal
aberration of the lens assembly 10a, wherein the three curves from
left to right are generated by an incident light having a
wavelength of: 0.486 .mu.m, 0.588 .mu.m, 0.656 .mu.m, respectively.
The simulation data as illustrated in FIGS. 2.about.3 are all
within standard ranges and suffice to verify that the lens assembly
10a of the present embodiment really possesses excellent optical
quality.
[0040] The lens assembly according to an embodiment of the present
invention includes a front lens group and a rear lens group. The
front group includes two lenses for receiving the light, but the
present invention is not limited thereto. The aperture value of the
lens is greater than or equivalent to 2.6. The rear group includes
a combined lens (a glued lens or a doublet lens) and an aspheric
lens for correcting aberration and color aberration. The minimum
distance between the two lenses of the doublet lens along the
optical axis is less than 0.05 mm. The doublet lens can be replaced
by a triplet lens, but the present invention is not limited
thereto. Each of the doublet lens, the glued lens, the combined
lens, and the triplet lens has corresponding adjacent surfaces
whose radii of curvature are substantially identical or similar.
The lens includes 4.about.7 lenses with a refractive power, and at
least two lenses have an Abbe number greater than 60.
[0041] In an embodiment, the lens assembly satisfies the following
condition: 6 mm<DL<20 mm. In another embodiment, the lens
assembly satisfies the following condition: 6.5 mm<DL<19 mm.
In an alternate embodiment, the lens assembly satisfies the
following condition: 7 mm<DL<18 mm. DL represents the
diameter of the lens surface closest to the image plane of the lens
assembly, so that the imaging light entering the lens can converge
to be near the size of the image sensor, and a better optical
effect can be obtained in a finite space.
[0042] In an embodiment, the lens assembly satisfies the following
conditions: 0.6<D1/DL and 1.5<LT/DL<2.4. In another
embodiment, the lens assembly satisfies the following conditions:
0.62<D1/DL and 1.55<LT/DL<2.35. In an alternate
embodiment, the lens assembly satisfies the following conditions:
0.64<D1/DL and 1.6<LT/DL<2.3. Thus, the image sensor
corresponds to a better design range of the total length of the
lenses. D1 is the diameter of a lens surface farthest away from the
image plane of the lens assembly. DL is the diameter of a lens
surface closest to the image plane of the lens assembly. LT is the
distance on the optical axis from the optical surface lens closest
to the image magnification side to the optical surface closest to
the image reduction side.
[0043] In an embodiment, the lens assembly satisfies the following
conditions: 0.4<D1/DL and 1.25<LT/DL<1.7. In another
embodiment, the lens assembly satisfies the following conditions:
0.42<D1/DL and 1.27<LT/DL<1.68. In an alternate
embodiment, the lens assembly satisfies the following conditions:
0.44<D1/DL and 1.29<LT/DL<1.66. Thus, the image sensor
corresponds to a better design range of the total length of the
lenses. D1 is the diameter of a lens surface farthest away from the
image plane of the lens assembly. DL is the diameter of a lens
surface closest to the image plane of the lens assembly. LT is the
distance on the optical axis from the optical surface lens closest
to the image magnification side to the optical surface closest to
the image reduction side.
[0044] The design of a lens assembly according to a second
embodiment of the present invention is disclosed below. FIG. 4 is a
schematic diagram of a lens assembly 10b according to a second
embodiment of the present invention. The first lens L1 and the
second lens L2 form a first lens group (such as a front lens group)
20 with a negative refractive power. The third lens L3, the fourth
lens L4 and the fifth lens L5 form a second lens group (such as a
rear lens group) 30 with a positive refractive power. In the
present embodiment, the refractive powers of the first lens L1 to
the fifth lens L5 of the lens assembly 10b sequentially are:
positive, negative, negative, positive, positive, all lenses are
formed of glass, and the fifth lens L5 is an aspheric lens. In the
present embodiment, the aspheric lens is formed by the glass
molding method. In an embodiment, aspheric glass lenses can be
replaced by aspheric plastics lenses. In the present embodiment,
the third lens L3 and the fourth lens L4 also form one combined
lens, but the present invention is not limited thereto. In the
present embodiment, the surface S1 has a diameter of 11.12 mm, and
the surface S10 has a diameter of 8.68 mm. The design parameters of
the lens assembly 10b and the peripheral elements are listed in
Table 3.
TABLE-US-00003 TABLE 3 F/# = 2.6; TTL = 25.0 (mm) DFOV =
45.5.degree.; LT/DL = 1.664 D1/DL = 1.281; IMH = 5.15 (mm) Radius
of curvature Interval Refractive Abbe Surface (mm) (mm) power
number Element S1 11.97 2.31 1.49 70.24 L1 (concave- convex) S2
217.63 0.10 S3 5.47 2.56 1.85 23.78 L2 (convex- concave) S4 3.00
2.04 S5 INF. 1.10 Aperture 14 S6 -4.96 0.50 1.6 39.24 L3
(bi-concave) S7 17.07 1.90 1.64 60.1 L4 (bi-convex) S8 -7.57 0.13
S9* 18.00 3.80 1.5 81.5 L5 (aspheric) S10* -5.28 9.03 S11 INF. 0.71
1.52 54.5 Filter 16 S12 INF. 0.83 S13 Image plane 18
[0045] The aspheric coefficient and the conic coefficient of each
order term of the aspheric lens surface according to the second
embodiment of the present invention are listed in Table 4.
TABLE-US-00004 TABLE 4 S9* S10* k 0 0 A -4.62E-04 7.77E-04 B
7.61E-05 -1.77E-05 C -4.61E-06 6.61E-06 D 2.99E-07 -3.85E-07 E
-5.96E-09 1.30E-08
[0046] The interval of the surface S1 is the distance on the
optical axis 12 from the surface S1 to the surface S2. The interval
of the surface S2 is the distance on the optical axis 12 from the
surface S2 to the surface S3. The interval of the surface S12 is
the distance on the optical path 12 from the surface S12 to the
image plane 18 of a visible light at an effective focal length. The
lens assembly includes at least two lenses whose Abbe numbers are
greater than 60.
[0047] FIGS. 5.about.6 are based on the simulation data of the lens
assembly 10b of the present embodiment. FIG. 5 is a ray fan plot of
a visible light, wherein X axis represents the position at which a
ray enters the pupil, Y axis represents a relative value of the
position at which the chief ray is projected to an image plane
(such as the image plane 18). FIG. 6 is a graph of longitudinal
aberration of the lens assembly 10b, wherein the three curves from
left to right are generated by an incident light having a
wavelength of: 0.486 .mu.m, 0.588 .mu.m, 0.656 .mu.m, respectively.
The simulation data as illustrated in FIGS. 5.about.6 are all
within standard ranges and suffice to verify that the lens assembly
10b of the present embodiment really possesses excellent optical
quality.
[0048] The design of a lens assembly according to a third
embodiment of the present invention is disclosed below. FIG. 7 is a
schematic diagram of a lens assembly 10c according to a third
embodiment of the present invention. The first lens L1 forms a
first lens group (such as a front lens group) 20 with a positive
refractive power. The second lens L2, the third lens L3, the fourth
lens L4 and the fifth lens L5 form one second lens group (such as a
rear lens group) 30 with a positive refractive power. In the
present embodiment, the refractive powers of the first lens L1 to
the fifth lens L5 of the lens assembly 10c sequentially are:
positive, positive, negative, positive, negative, all lenses are
formed of glass, and the fifth lens L5 is an aspheric lens. In the
present embodiment, the aspheric lens is formed by the glass
molding method. In an embodiment, aspheric glass lenses can be
replaced by aspheric plastics lenses. In the present embodiment,
the second lens L2 and the third lens L3 also form one combined
lens, but the present invention is not limited thereto. In the
present embodiment, the surface S1 has a diameter of 4.64 mm, and
the surface S10 has a diameter of 9.58 mm. The design parameters of
the lens assembly 10c and the peripheral elements are listed in
Table 5.
TABLE-US-00005 TABLE 5 F/# = 3.0; TTL = 15.9 (mm) DFOV =
46.9.degree.; LT/DL = 1.454 D1/DL = 0.484; IMH = 5.15 (mm) Radius
of curvature Interval Refractive Abbe Surface (mm) (mm) power
number Element S1 16.75 1.06 1.76 40.1 L1 (plano-convex) S2 INF.
0.10 S3 INF. 0.15 Aperture 14 S4 6.73 1.60 1.62 63.3 L2 (bi-convex)
S5 -6.84 2.20 1.67 38.15 L3 (bi-concave) S6 5.32 2.91 S7 10.40 3.15
1.62 63.3 L4 (bi-convex) S8 -7.95 1.94 S9* -7.47 0.80 1.73 40.5 L5
(aspheric) S10* 17.08 0.47 S11 INF. 0.71 1.52 54.5 Filter 16 S12
INF. 0.83 S13 Image plane 18
[0049] The aspheric coefficient and the conic coefficient of each
order term of the aspheric lens surface according to the second
embodiment of the present invention are listed in Table 6.
TABLE-US-00006 TABLE 6 S9* S10* k 0 0 A -9.13E-03 -8.03E-03 B
6.52E-04 5.00E-04 C -2.47E-05 -2.29E-05 D 4.26E-07 6.26E-07 E
-7.58E-09 -5.25E-09 F 5.83E-10 -2.04E-10 G -1.43E-11 4.66E-12
[0050] The interval of the surface S1 is the distance on the
optical axis 12 from the surface S1 to the surface S2. The interval
of the surface S2 is the distance on the optical axis 12 from the
surface S2 to the surface S3. The interval of the surface S12 is
the distance on the optical path 12 from the surface S12 to the
image plane 18 of a visible light at an effective focal length. The
lens assembly includes at least two lenses whose Abbe numbers are
greater than 60.
[0051] FIGS. 8.about.9 are based on the simulation data of the lens
assembly 10c of the present embodiment. FIG. 8 is a ray fan plot of
a visible light, wherein X axis represents the position at which a
ray enters the pupil, Y axis represents a relative value of the
position at which the chief ray is projected to an image plane
(such as the image plane 18). FIG. 9 is a graph of longitudinal
aberration of the lens assembly 10c, wherein the three curves from
left to right are generated by an incident light having a
wavelength of: 0.486 .mu.m, 0.588 .mu.m, 0.656 .mu.m, respectively.
The simulation data as illustrated in FIGS. 8.about.9 are all
within standard ranges and suffice to verify that the lens assembly
10c of the present embodiment really possesses excellent optical
quality.
[0052] The design of a lens assembly according to a fourth
embodiment of the present invention is disclosed below. FIG. 10 is
a schematic diagram of a lens assembly 10d according to a fourth
embodiment of the present invention.
[0053] In the present embodiment, the refractive powers of the
first lens L1 to the fifth lens L5 of the lens assembly 10d
sequentially are: positive, negative, positive, positive, negative,
all lenses are formed of glass, and the fifth lens L5 is an
aspheric lens. In the present embodiment, the aspheric lens is
formed by the glass molding method. In an embodiment, aspheric
glass lenses can be replaced by aspheric plastics lenses. In the
present embodiment, the second lens L2 and the third lens L3 also
form one combined lens, but the present invention is not limited
thereto. In the present embodiment, the surface S1 has a diameter
of 4.74 mm, and the surface S10 has a diameter of 9.0 mm. The
design parameters of the lens assembly 10d and the peripheral
elements are listed in Table 7.
TABLE-US-00007 TABLE 7 F/# = 2.6; TTL = 15.95 (mm) DFOV =
47.3.degree.; LT/DL = 1.484 D1/DL = 0.523; IMH = 5.15 (mm) Radius
of Interval Refractive Abbe Surface curvature (mm) (mm) power
number Element S1 INF. 0 Aperture 14 S2 6.89 1.56 2 29.13 L1
(concave- convex) S3 29.59 1.51 S4 -24.20 0.50 1.92 18.9 L2
(bi-concave) S5 5.50 1.71 1.49 70.24 L3 (concave- convex) S6 44.10
1.04 S7 12.80 3.25 2 29.13 L4 (bi-convex) S8 -17.39 2.12 S9* -9.80
1.75 1.58 59.4 L5 (aspheric) S10* 17.21 0.97 S11 INF. 0.71 1.52
54.5 Filter 16 S12 INF. 0.83 S13 Image plane 18
[0054] The aspheric coefficient and the conic coefficient of each
order term of the aspheric lens surface according to the second
embodiment of the present invention are listed in Table 8.
TABLE-US-00008 TABLE 8 S9* S10* k 0 0 A -4.67E-03 -3.81E-03 B
4.67E-05 4.88E-05 C 5.94E-07 -2.20E-07
[0055] The interval of the surface S1 is the distance on the
optical axis 12 from the surface S1 to the surface S2. The interval
of the surface S2 is the distance on the optical axis 12 from the
surface S2 to the surface S3. The interval of the surface S12 is
the distance on the optical path 12 from the surface S12 to the
image plane 18 of a visible light at an effective focal length. The
lens assembly includes at least two lenses whose Abbe numbers are
greater than 58.
[0056] FIGS. 11.about.12 are based on the simulation data of the
lens assembly 10d of the present embodiment. FIG. 11 is a ray fan
plot of a visible light, wherein X axis represents the position at
which a ray enters the pupil, Y axis represents a relative value of
the position at which the chief ray is projected to an image plane
(such as the image plane 18). FIG. 12 is a graph of longitudinal
aberration of the lens assembly 10d, wherein the three curves from
left to right are generated by an incident light having a
wavelength of: 0.486 .mu.m, 0.588 .mu.m, 0.656 .mu.m, respectively.
The simulation data as illustrated in FIGS. 11.about.12 are all
within standard ranges and suffice to verify that the lens assembly
10d of the present embodiment really possesses excellent optical
quality.
[0057] The design of a lens assembly according to a fifth
embodiment of the present invention is disclosed below. FIG. 13 is
a schematic diagram of a lens assembly 10e according to a fifth
embodiment of the present invention. In the present embodiment, the
refractive powers of the first lens L1 to the seventh lens L7 of
the lens assembly 10e sequentially are: negative, positive,
positive, negative, positive, positive, negative, and all lenses
are spherical glass lenses. The first lens L1, the second lens L2
and the third lens L3 form a first lens group (such as a front lens
group) 20 with a positive refractive power. The fourth lens L4, the
fifth lens L5, the sixth lens L6 and the seventh lens L7 form a
second lens group (such as a rear lens group) 30 with a positive
refractive power. In the present embodiment, the first lens L1 and
the second lens L2 also form one combined lens, but the present
invention is not limited thereto. In the present embodiment, the
surface S1 has a diameter of 6.0 mm, and the surface S13 has a
diameter of 9.2 mm. The design parameters of the lens assembly 10e
and the peripheral elements are listed in Table 9.
TABLE-US-00009 TABLE 9 F/# = 2.6; TTL = 24.88 (mm) DFOV =
47.2.degree.; LT/DL = 2.251 D1/DL = 0.616; IMH = 5.15 (mm) Radius
of curvature Interval Refractive Abbe Surface (mm) (mm) power
number Element S1 -11.83 0.92 1.72 29.52 L1 (bi-concave) S2 15.95
1.62 1.9 31.32 L2 (bi-convex) S3 -15.95 0.10 S4 24.56 1.33 1.9
31.32 L3 (plano- convex) S5 INF. 0.39 S6 INF. 2.38 Aperture 14 S7
-6.90 0.50 1.72 29.52 L4 (bi-concave) S8 23.31 0.46 S9* 116.62 2.43
1.6 67.72 L5 (bi-convex) S10* -8.02 0.10 S11 12.87 3.27 1.6 67.72
L6 (bi-convex) S12 -16.87 7.79 S13 -7.07 0.63 1.62 36.62 L7
(convex- concave) S14 -18.86 0.64 S15 INF. 0.71 1.52 54.5 Filter 16
S16 INF. 0.82 S17 INF. Image plane 18
[0058] The interval of the surface S1 is the distance on the
optical axis 12 from the surface S1 to the surface S2. The interval
of the surface S2 is the distance on the optical axis 12 from the
surface S2 to the surface S3. The interval of the surface S16 is
the distance on the optical path 12 from the surface S16 to the
image plane 18 of a visible light at an effective focal length. The
lens assembly includes at least two lenses whose Abbe numbers are
greater than 60.
[0059] FIGS. 14.about.15 are based on the simulation data of the
lens assembly 10e of the present embodiment. FIG. 14 is a ray fan
plot of a visible light, wherein X axis represents the position at
which a ray enters the pupil, Y axis represents a relative value of
the position at which the chief ray is projected to an image plane
(such as the image plane 18). FIG. 15 is a graph of longitudinal
aberration of the lens assembly 10e, wherein the three curves from
left to right are generated by an incident light having a
wavelength of: 0.486 .mu.m, 0.588 .mu.m, 0.656 .mu.m, respectively.
The simulation data as illustrated in FIGS. 14.about.15 are all
within standard ranges and suffice to verify that the lens assembly
10e of the present embodiment really possesses excellent optical
quality.
[0060] The design of a lens assembly according to a sixth
embodiment of the present invention is disclosed below. FIG. 16 is
a schematic diagram of a lens assembly 10f according to a sixth
embodiment of the present invention. In the present embodiment, the
refractive powers of the first lens L1 to the sixth lens L6 of the
lens assembly 10f sequentially are: positive, negative, positive,
negative, positive, positive, and lenses L1.about.L5 are spherical
glass lenses. The first lens L1, the second lens L2 and the third
lens L3 form a first lens group (such as a front lens group) 20
with a negative refractive power. The fourth lens L4, the fifth
lens L5 and the sixth lens L6 form a second lens group (such as a
rear lens group) 30 with a positive refractive power. In the
present embodiment, the first lens L1 and the second lens L2 form
one cemented lens, and the fourth lens L4 and the fifth lens L5
form the other cemented lens but the present invention is not
limited thereto. In the present embodiment, the surface S1 has a
diameter of 10.0 mm, and the surface S11 has a diameter of 7.0 mm.
The design parameters of the lens assembly 10f and the peripheral
elements are listed in Table 10.
TABLE-US-00010 TABLE 10 F/# = 2.75; TTL = 25.05 (mm) DFOV =
48.4.degree.; LT/DL = 2.051 D1/DL = 1.429; IMH = 5.15 (mm) Radius
of Interval Refractive Abbe Surface curvature (mm) (mm) power
number Element S1 6.62 2.61 2 29.13 L1 (concave- convex) S2 10.39
0.57 1.76 26.52 L2 (convex- concave) S3 3.59 2.01 S4 9.45 1.33 2
28.27 L3 (concave- convex) S5 9.90 1.11 S6 INF. 0.77 Aperture 14 S7
-6.95 0.50 1.78 25.68 L4 (bi-concave) S8 8.50 1.82 1.9 31.32 L5
(bi-convex) S9 -11.31 0.13 S10* 12.06 3.50 1.5 81.5 L6 (aspheric)
S11* -6.57 1.00 S12 INF. 0.21 52 54.5 Filter 16 S13 INF. 9.94 S14
INF. Image plane 18
[0061] The aspheric coefficient and the conic coefficient of each
order term of the aspheric lens surface according to the sixth
embodiment of the present invention are listed in Table 11.
TABLE-US-00011 TABLE 11 S10* S11* k 0 0 A 1.41E-04 9.91E-04 B
1.84E-05 -3.16E-05 C 5.34E-06 1.70E-05 D -1.40E-06 -2.58E-06 E
2.38E-07 2.45E-07 F -2.03E-08 -1.20E-08 G 6.71E-10 2.43E-10
[0062] The interval of the surface S1 is the distance on the
optical axis 12 from the surface S1 to the surface S2. The interval
of the surface S2 is the distance on the optical axis 12 from the
surface S2 to the surface S3. The interval of the surface S13 is
the distance on the optical path 12 from the surface S13 to the
image plane 18 of a visible light at an effective focal length. The
lens assembly 10f includes at least two lenses whose Abbe numbers
are greater than 50.
[0063] FIGS. 17.about.18 are based on the simulation data of the
lens assembly 10f of the present embodiment. FIG. 17 is a ray fan
plot of a visible light, wherein X axis represents the position at
which a ray enters the pupil, Y axis represents a relative value of
the position at which the chief ray is projected to an image plane
(such as the image plane 18). FIG. 18 is a graph of longitudinal
aberration of the lens assembly 10f, wherein the three curves from
left to right are generated by an incident light having a
wavelength of: 0.486 .mu.m, 0.588 .mu.m, 0.656 .mu.m, respectively.
The simulation data as illustrated in FIGS. 17.about.18 are all
within standard ranges and suffice to verify that the lens assembly
10f of the present embodiment really possesses excellent optical
quality.
[0064] Through the design disclosed in the embodiments of the
present invention, an image lens possessing the optical features of
excellent optical quality and lightweight and capable of reducing
manufacturing cost and improving optical quality is provided. Based
on the design that the optical lens includes 4.about.7 lenses and
that the total track length (TTL) from the lens to the sensor is
less than 25 mm and the maximum outer diameter of the mechanism is
less than 14 mm, the optical lens assembly advantageously possesses
the features of larger aperture, higher resolution (5 million
pixels), lighter weight, longer effective focal length (EFL=12 mm),
and larger target surface (1/2.5 inch), the manufacturing cost can
be reduced and the optical quality can be improved.
[0065] While the invention has been described by way of example and
in terms of the preferred embodiment (s), it is to be understood
that the invention is not limited thereto. On the contrary, it is
intended to cover various modifications and similar arrangements
and procedures, and the scope of the appended claims therefore
should be accorded the broadest interpretation so as to encompass
all such modifications and similar arrangements and procedures.
* * * * *