U.S. patent application number 13/196467 was filed with the patent office on 2013-02-07 for optical lens system.
The applicant listed for this patent is Shu Tzu Lai. Invention is credited to Shu Tzu Lai.
Application Number | 20130033766 13/196467 |
Document ID | / |
Family ID | 47562306 |
Filed Date | 2013-02-07 |
United States Patent
Application |
20130033766 |
Kind Code |
A1 |
Lai; Shu Tzu |
February 7, 2013 |
OPTICAL LENS SYSTEM
Abstract
An optical lens system comprises, in order from the object side
to the image side: a first lens element with a positive refractive
power having a convex object-side surface, one of the object-side
surface and an image-side surface being aspheric; a stop; a second
lens element with a negative refractive power having a concave
object-side surface, one of the object-side surface and an
image-side surface being aspheric; a third lens element with a
positive refractive power having a concave image-side surface, one
of an object-side surface and the image-side surface being
aspheric. Focal lengths of the first, second and third lens
elements are f1, f2, f3, respectively, they satisfy the relations:
0.4<|f1|/|f2|<1.0; 0.5<|f2|/|f3|<1.3. If |f1|/|f2| and
|f2|/|f3| satisfy the above relations, it can provide a wide field
of view and improve the resolution. Contrarily, the performance and
resolution of the optical lens system will be reduced.
Inventors: |
Lai; Shu Tzu; (Taichung
City, TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Lai; Shu Tzu |
Taichung City |
|
TW |
|
|
Family ID: |
47562306 |
Appl. No.: |
13/196467 |
Filed: |
August 2, 2011 |
Current U.S.
Class: |
359/716 |
Current CPC
Class: |
G02B 13/0035 20130101;
G02B 13/18 20130101 |
Class at
Publication: |
359/716 |
International
Class: |
G02B 13/18 20060101
G02B013/18; G02B 9/16 20060101 G02B009/16 |
Claims
1. An optical lens system comprising, in order from an object side
to an image side: a first lens element with a positive refractive
power having a convex object-side surface, at least one of the
object-side and an image-side surfaces of the first lens element
being aspheric; a stop; a second lens element with a negative
refractive power having a concave object-side surface, at least one
of the object-side and an image-side surfaces of the second lens
element being aspheric; a third lens element with a positive
refractive power having a concave image-side surface, at least one
of an object-side and the image-side surfaces of the third lens
element being aspheric; wherein a focal length of the first lens
element is f1, a focal length of the second lens element is f2, and
they satisfy the relations: 0.4<|f1|/|f2|<1.0;
0.5<|f2|/|f3|<1.3.
2. The optical lens system as claimed in claim 1, wherein a focal
length of the optical lens system is f, a focal length of the first
lens element and the second lens element combined is f12, and they
satisfy the relation: 1.3<|f12|/|f|<2.5.
3. The optical lens system as claimed in claim 1, wherein a focal
length of the optical lens system is f, a focal length of the
second lens element and the third lens element combined is f23, and
they satisfy the relation: 25<|f23|/|f|<70.
4. The optical lens system as claimed in claim 1, wherein a focal
length of the optical lens system is f, a distance between the
object-side surface of the first lens element and an image plane is
TL, and they satisfy the relation: 0.6<|f|/|TL|<1.0.
5. The optical lens system as claimed in claim 1, wherein the first
lens element is made of plastic, the image-side surface of the
first lens element is convex, and the object-side surface and the
image-side surface of the first lens element are aspheric.
6. The optical lens system as claimed in claim 1, wherein the
second lens element is made of plastic, the image-side surface of
the second lens element is convex, and the object-side surface and
the image-side surface of the second lens element are aspheric.
7. The optical lens system as claimed in claim 1, wherein the third
lens element is made of plastic, the object-side surface of the
third lens element is convex, and the object-side surface and the
image-side surface of the third lens element are aspheric.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an optical lens system, and
more particularly to a three-piece optical lens system.
[0003] 2. Description of the Prior Art
[0004] In recent years, with the popularity of the mobile phone
cameras, the optical lens system has become smaller in size, and
the electronic sensor of a general digital camera is typically a
CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide
Semiconductor) sensor. Due to advances in semiconductor
manufacturing, the pixel size of sensor has been reduced
continuously, and miniaturized optical lens systems have
increasingly higher resolution. Therefore, there's an increasing
demand for an imaging lens system with better image quality.
[0005] Conventional miniaturized lens systems mostly consist of
three lens elements as shown in FIG. 3, from the object side to the
image side: a first lens element 91 with positive refractive power,
a second lens element 92 with negative refractive power and a third
lens element 93 with positive refractive power. Such arrangements
are favorable to correct various aberrations, however, the second
lens element 92 is negative and the refractive power of the third
lens element 93 is not big, such that the refractive power of the
first lens element 91 must be big enough to provide the refractive
power of the optical lens system, which will increase the
sensitivity of the optical lens system and reduce the yield
rate.
[0006] Therefore, the present invention is aimed at providing an
optical lens system which can improve the yield rate and provide
great image quality.
[0007] The present invention mitigates and/or obviates the
aforementioned disadvantages.
SUMMARY OF THE INVENTION
[0008] The primary objective of the present invention is to provide
an optical lens system capable of effectively providing a good
image quality and improving the yield rate.
[0009] An optical lens system in accordance with the present
invention comprises, in order from the object side to the image
side: a first lens element with a positive refractive power having
a convex object-side surface, at least one of the object-side and
an image-side surfaces of the first lens element being aspheric; a
stop; a second lens element with a negative refractive power having
a concave object-side surface, at least one of the object-side and
an image-side surfaces of the second lens element being aspheric; a
third lens element with a positive refractive power having a
concave image-side surface, at least one of an object-side and the
image-side surfaces of the third lens element being aspheric. In
the optical lens system, the focal length of the first lens element
is f1, the focal length of the second lens element is f2, the focal
length of the third lens element is f3, and they satisfy the
relations: 0.4<|f1|/|f2|<1.0; 0.5<|f2|/|f3|<1.3.
[0010] If |f1|/|f2| and |f2|/|f3| satisfy the above relations: a
wide field of view can be provided and the resolution can be
improved evidently. Contrarily, If |f1|/|f2| and |f2|/|f3| exceed
the above ranges, the performance and resolution of the optical
lens system with a wide field of view will be reduced, and the
yield rate will be low.
[0011] According to one aspect of the present optical lens system,
the focal length of the optical lens system is f, the focal length
of the first lens element and the second lens element combined is
f12, and they satisfy the relation: 1.3<|f12|/|f|<2.5. If
|f12|/|f| satisfies the above relation, a wide field of view can be
provided and the resolution can be improved evidently. Contrarily,
If |f12|/|f| exceeds the above range, the performance and
resolution of the optical lens system with a wide field of view
will be reduced, and the yield rate will be low.
[0012] According to another aspect of the present optical lens
system, the focal length of the optical lens system is f, the focal
length of the second lens element and the third lens element
combined is f23, and they satisfy the relation:
25<|f23|/|f|<70. If |f23|/|f| satisfies the above relation, a
wide field of view can be provided and the resolution can be
improved evidently. Contrarily, If |f23|/|f| exceeds the above
range, the performance and resolution of the optical lens system
with a wide field of view will be reduced, and the yield rate will
be low.
[0013] According to another aspect of the present optical lens
system, the focal length of the optical lens system is f, the
distance between the object-side surface of the first lens element
and the image plane is TL, and they satisfy the relation:
0.6<|f|/|TL|<1.0. If |f|/|TL| satisfies the above relation, a
wide field of view can be provided and the resolution can be
improved evidently. Contrarily, If |f|/|TL| exceeds the above
range, the performance and resolution of the optical lens system
with a wide field of view will be reduced, and the yield rate will
be low.
[0014] The present invention will be presented in further details
from the following descriptions with the accompanying drawings,
which show, for purpose of illustrations only, the preferred
embodiments in accordance with the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1A shows an optical lens system in accordance with a
first embodiment of the present invention;
[0016] FIG. 1B shows the longitudinal spherical aberration curve,
the astigmatic field curve, and the distortion curve of the first
embodiment of the present invention;
[0017] FIG. 2A shows an optical lens system in accordance with a
second embodiment of the present invention;
[0018] FIG. 2B shows the longitudinal spherical aberration curve,
the astigmatic field curve, and the distortion curve of the second
embodiment of the present invention; and
[0019] FIG. 3 shows a conventional optical lens system.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0020] Referring to FIG. 1A, which shows an optical lens system in
accordance with a first embodiment of the present invention, and
FIG. 1B shows the longitudinal spherical aberration curves, the
astigmatic field curves, and the distortion curve of the first
embodiment of the present invention. An optical lens system in
accordance with the first embodiment of the present invention
comprises, in order from the object side A to the image side B:
[0021] A first lens element 110 with a positive refractive power
made of plastic has a convex object-side surface 111 and a concave
image-side surface 112, and the object-side surface 111 and the
image-side surface 112 of the first lens element 110 are
aspheric.
[0022] A stop 120.
[0023] A second lens element 130 with a negative refractive power
made of plastic has a concave object-side surface 131 and a convex
image-side surface 132, and the object-side surface 131 and the
image-side surface 132 of the second lens element 130 are
aspheric.
[0024] A third lens element 140 with a positive refractive power
made of plastic has a convex object-side surface 141 and a concave
image-side surface 142, and the object-side surface 141 and the
image-side surface 142 of the third lens element 140 are
aspheric.
[0025] An IR cut filter 150 made of glass is located between the
image-side surface 142 of the third lens element 140 and an image
plane 160 and has no influence on the focal length of the optical
lens system.
[0026] The equation for the aspheric surface profiles of the first
embodiment is expressed as follows:
z = ch 2 1 + [ 1 - ( k + 1 ) c 2 h 2 ] 0.5 + Ah 4 + Bh 6 + Ch 8 +
Dh 10 + Eh 12 + Gh 14 + ##EQU00001##
[0027] wherein:
[0028] z represents the value of a reference position with respect
to a vertex of the surface of a lens and a position with a height h
along the optical axis 170
[0029] k represents the conic constant;
[0030] c represents the reciprocal of the radius of curvature;
[0031] A, B, C, D, E, G, . . . : represent the high-order aspheric
coefficients,
[0032] In the first embodiment of the present optical lens system,
the focal length of the optical lens system is f, and it satisfies
the relation:
[0033] f=2.5.
[0034] In the first embodiment of the present optical lens system,
the f-number of the optical lens system is Fno, and it satisfies
the relation:
[0035] Fno=2.8.
[0036] In the first embodiment of the present optical lens system,
the field of view of the optical lens system is 2.omega., and it
satisfies the relation: 2.omega.=71.degree..
[0037] In the first embodiment of the present optical lens system,
the focal length of the first lens element 110 is f1, the focal
length of the second lens element 130 is f2, and they satisfy the
relation:
[0038] |f1|/|f2|=0.698.
[0039] In the first embodiment of the present optical lens system,
the focal length of the second lens element 130 is f2, the focal
length of the third lens element 140 is f3, and they satisfy the
relation:
[0040] |f2|/|f3|=0.904.
[0041] In the first embodiment of the present optical lens system,
the focal length of the optical lens system is f, the focal length
of the first lens element 110 and the second lens element 130
combined is f12, and they satisfy the relation:
[0042] |f12|/|f|=1.903.
[0043] In the first embodiment of the present optical lens system,
the focal length of the optical lens system is f, the focal length
of the second lens element 130 and the third lens element 140
combined is f23, and they satisfy the relation:
[0044] |f23|/|f|=39.871.
[0045] In the first embodiment of the present optical lens system,
the focal length of the optical lens system is f, the distance
between the object-side surface 111 of the first lens element 110
and the image plane 160 is TL, and they satisfy the relation:
[0046] |f|/|TL|=0.801.
[0047] The detailed optical data of the first embodiment is shown
in table 1, and the aspheric surface data is shown in table 2,
wherein the units of the radius of curvature, the thickness and the
focal length are expressed in mm. In the tables 1 and 2, the
surfaces 1 and 2 represent the object-side surface 111 and the
image-side surface 112 of the first lens element 110, respectively,
the surfaces 4 and 5 represent the object-side surface 131 and the
image-side surface 132 of the second lens element 130,
respectively, and the surfaces 6 and 7 represent the object-side
surface 141 and the image-side surface 142 of the third lens
element 140, respectively.
TABLE-US-00001 TABLE 1 (Embodiment 1) f(focal length) = 2.5 mm, Fno
= 2.8, 2.omega. = 71.degree.. Surface # Curvature Radius Thickness
Material nd vd 0 Object Infinity Infinity 1 Lens 1 0.810569(ASP)
0.464811 Plastic 1.535 56 2 2.014131(ASP) 0.119456 3 Stop Infinity
0.306195 4 Lens 2 -0.662(ASP) 0.324965 Plastic 1.632 23 5
-1.16917(ASP) 0.20916 6 Lens 3 1.193874(ASP) 0.749598 Plastic 1.535
56 7 2.521003(ASP) 0.11 8 IR-filter Infinity 0.21 Glass 1.5168
64.167336 9 Infinity 0.631495 10 Image Infinity
TABLE-US-00002 TABLE 2 Aspheric Coefficients Surface # 1 2 4 5 6 7
k = -0.03884 4.049545 1.22589 1.744959 -14.74451 1.315892 A =
0.044644 -0.06381 0.025826 -1.03006 -0.18065 -0.23157 B = 0.511206
0.527859 0.204989 3.034897 0.175589 0.07323 C = -2.70739 -2.6657
45.96038 -7.72808 -0.0725 -0.03231 D = 9.15671 -50.3156 -465.378
9.470822 0.012455 0.01257 E = -11.6546 342.1318 1519.958 1.521
0.000329 -0.00242
[0048] Referring to FIG. 2A, which shows an optical lens system in
accordance with a second embodiment of the present invention, and
FIG. 2B shows the longitudinal spherical aberration curves, the
astigmatic field curves, and the distortion curve of the second
embodiment of the present invention. The second embodiment of the
present invention comprises, in order from the object side A to the
image side B:
[0049] A first lens element 210 with a positive refractive power
made of plastic has a convex object-side surface 211 and a concave
image-side surface 212, and the object-side surface 211 and the
image-side surface 212 of the first lens element 210 are
aspheric.
[0050] A stop 220.
[0051] A second lens element 230 with a negative refractive power
made of plastic has a concave object-side surface 231 and a convex
image-side surface 232, and the object-side surface 231 and the
image-side surface 232 of the second lens element 230 are
aspheric.
[0052] A third lens element 240 with a positive refractive power
made of plastic has a convex object-side surface 241 and a concave
image-side surface 242, and the object-side surface 241 and the
image-side surface 242 of the third lens element 240 are
aspheric.
[0053] An IR cut filter 250 made of glass is located between the
image-side surface 242 of the third lens element 240 and an image
plane 260 and has no influence on the focal length of the optical
lens system.
[0054] The equation for the aspheric surface profiles of the second
embodiment is expressed as follows:
z = ch 2 1 + [ 1 - ( k + 1 ) c 2 h 2 ] 0.5 + Ah 4 + Bh 6 + Ch 8 +
Dh 10 + Eh 12 + Gh 14 + ##EQU00002##
[0055] wherein:
[0056] z represents the value of a reference position with respect
to a vertex of the surface of a lens and a position with a height h
along the optical axis 170
[0057] k represents the conic constant;
[0058] c represents the reciprocal of the radius of curvature
[0059] A, B, C, D, E, G, . . . : represent the high-order aspheric
coefficients.
[0060] In the second embodiment of the present optical lens system,
the focal length of the optical lens system is f, and it satisfies
the relation:
[0061] f=2.51.
[0062] In the second embodiment of the present optical lens system,
the f-number of the optical lens system is Fno, and it satisfies
the relation:
[0063] Fno=2.8.
[0064] In the second embodiment of the present optical lens system,
the field of view of the optical lens system is 2.omega., and it
satisfies the relation:
[0065] 2.psi.=69.degree..
[0066] In the second embodiment of the present optical lens system,
the focal length of the first lens element 210 is f1, the focal
length of the second lens element 230 is f2, and they satisfy the
relation:
[0067] |f1|/|f2|=0.716.
[0068] In the second embodiment of the present optical lens system,
the focal length of the second lens element 230 is f2, the focal
length of the third lens element 240 is f3, and they satisfy the
relation:
[0069] |f2|/|f3|=0.89.
[0070] In the second embodiment of the present optical lens system,
the focal length of the optical lens system is f, the focal length
of the first lens element 210 and the second lens element 230
combined is f12, and they satisfy the relation:
[0071] |f12|/|f|=1.925.
[0072] In the second embodiment of the present optical lens system,
the focal length of the optical lens system is f, the focal length
of the second lens element 230 and the third lens element 240
combined is f23, and they satisfy the relation:
[0073] |f23|/|f|=55.288.
[0074] In the second embodiment of the present optical lens system,
the focal length of the optical lens system is f, the distance
between the object-side surface 211 of the first lens element 210
and the image plane 260 is TL, and they satisfy the relation:
[0075] |f|/|TL|=0.8.
[0076] The detailed optical data of the second embodiment is shown
in table 3, and the aspheric surface data is shown in table 4,
wherein the units of the radius of curvature, the thickness and the
focal length are expressed in mm. In the tables 3 and 4, the
surfaces 1 and 2 represent the object-side surface 211 and the
image-side surface 212 of the first lens element 210, respectively,
the surfaces 4 and 5 represent the object-side surface 231 and the
image-side surface 232 of the second lens element 230,
respectively, and the surfaces 6 and 7 represent the object-side
surface 241 and the image-side surface 242 of the third lens
element 240, respectively.
TABLE-US-00003 TABLE 3 (Embodiment 2) f(focal length) = 2.51 mm,
Fno = 2.8, 2.omega. = 69.degree.. Surface # Curvature Radius
Thickness Material nd vd 0 Object Infinity Infinity 1 Lens 1
0.804669(ASP) 0.489057 Plastic 1.535 56 2 1.968962(ASP) 0.114793 3
Stop Infinity 0.270602 4 Lens 2 -0.673(ASP) 0.3246 Plastic 1.632 23
5 -1.21451 (ASP).sup. 0.23358 6 Lens 3 1.190834(ASP) 0.751439
Plastic 1.535 56 7 2.573349(ASP) 0.11 8 IR-filter Infinity 0.21
Glass 1.5168 64.167336 9 Infinity 0.634696 10 Image Infinity
TABLE-US-00004 TABLE 4 Aspheric Coefficients Surface # 1 2 4 5 6 7
k = -0.02980639 3.518053 2.02648 2.084079 -13.5649 1.286384 A =
0.061269 -0.05164 -0.02568 -0.97226 -0.18337 -0.2274 B = 0.469007
-0.06852 -0.58025 3.355579 0.182023 0.070731 C = -3.02649 -3.51569
45.6459 -7.32147 -0.07214 -0.02943 D = 9.606462 -50.2179 -325.166
9.251752 0.011727 0.012417 E = -13.7504 322.1578 1500.349 1.026458
-0.00038 -0.00248
TABLE-US-00005 TABLE 5 Embodiment 1 Embodiment 2 f 2.5 2.51 Fno 2.8
2.8 2.omega. 71 69 |f1|/|f2| 0.698 0.716 |f2|/|f3| 0.904 0.89
|f12|/|f| 1.903 1.925 |f23|/|f| 39.871 55.288 |f|/|TL| 0.801
0.8
[0077] It is to be noted that the tables 1-4 show different data
from the different embodiments, however, the data of the different
embodiments is obtained from experiments. Therefore, any product of
the same structure is deemed to be within the scope of the present
invention even if it uses different data. Table 5 lists the
relevant data for the various embodiments of the present
invention.
[0078] In the present optical lens system, the lens elements can be
made of glass or plastic. If the lens elements are made of glass,
there is more freedom in distributing the refractive power of the
optical lens system. If the lens elements are made of plastic, the
cost will be effectively reduced.
[0079] In the present optical lens system, if the object-side or
the image-side surface of the lens elements is convex, the
object-side or the image-side surface of the lens elements in
proximity of the optical axis is convex. If the object-side or the
image-side surface of the lens elements is concave, the object-side
or the image-side surface of the lens elements in proximity of the
optical axis is concave.
[0080] While we have shown and described various embodiments in
accordance with the present invention, it should be clear to those
skilled in the art that further embodiments may be made without
departing from the scope of the present invention.
* * * * *