(12) United States Patent
`Tang et al.
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 8,363,337 B2
`Jan. 29, 2013
`
`USOO8363337B2
`
`(54) IMAGING LENS ASSEMBLY
`(75) Inventors: Hsiang Chi Tang, Taichung (TW);
`Chun Shan Chen, Taichung (TW);
`Tsung Han Tsai, Taichung (TW)
`Assignee: Largan Precision Co., Ltd., Taichung
`(TW)
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 257 days.
`Appl. No.: 12/823,713
`
`(73)
`
`(*)
`
`Notice:
`
`(21)
`(22)
`(65)
`
`Filed:
`
`Jun. 25, 2010
`
`Prior Publication Data
`US 2011/0249346A1
`Oct. 13, 2011
`
`Foreign Application Priority Data
`
`(30)
`Apr. 8, 2010 (TW) ............................... 9911086OA
`
`(51)
`
`(52)
`(58)
`
`(56)
`
`Int. C.
`(2006.01)
`GO2B 9/60
`(2006.01)
`GO2B 13/18
`U.S. Cl. ........................................ 359/764; 35.9/714
`Field of Classification Search .......... 359/763 764,
`359/754 757, 771 773,776 778, 713 714
`See application file for complete search history.
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`7,365,920 B2
`4/2008 Noda.
`7,643,225 B1
`1/2010 Tsai
`
`
`
`7,864.454 B1* 1/2011 Tang et al. .................... 359,764
`7.965,454 B2 * 6/2011 Tanaka et al. ..
`... 359,754
`2010, O220229 A1* 9, 2010 Sano ..............
`Riis
`2010, O253829 A1* 10, 2010 Shinohara ..
`... 359,764
`2010, O254029 A1* 10, 2010 Shinohara ..
`2011/00 13069 A1
`1/2011 Chen ..................
`... 348,335
`2011/01 15965 A1* 5/2011 Engelhardt et al.
`348/345
`2011/0134305 A1
`6, 2011 Sano et al. .................... 348/340
`
`FOREIGN PATENT DOCUMENTS
`M369459
`11, 2009
`TW
`WO WO 2010/0241.98
`* 3/2010
`* cited by examiner
`
`Primary Examiner — Jordan Schwartz
`(74) Attorney, Agent, or Firm — Morris, Manning & Martin,
`LLP, Tim Tingkang Xia, Esq.
`
`ABSTRACT
`(57)
`This invention provides an imaging lens assembly including
`five lens elements with refractive power, in order from an
`object side toward an image side: a first lens with positive
`refractive power having a convex object-side Surface, a sec
`ond lens with negative refractive power, a third lens having a
`concave object-side Surface, a fourth lens with positive
`refractive power having an object-side Surface and a convex
`image-side Surface, and at least one of both surfaces thereof
`being aspheric, a fifth lens with negative refractive power
`having a concave image-side Surface with at least one inflec
`tion point formed thereon. An aperture stop is positioned
`between an imaged object and the second lens. The imaging
`lens assembly further comprises an electronic sensor on
`which an object is imaged. With Such arrangement, the size
`and the optical sensitivity of the lens assembly can be
`reduced. A high image resolution is also obtained.
`23 Claims, 25 Drawing Sheets
`
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`U.S. Patent
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`Jan. 29, 2013
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`Sheet 1 of 25
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`US 8,363,337 B2
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`s
`
`s \XI Ns,
`YES :
`s RNS See
`if SINDANss
`A V y
`s &
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`U.S. Patent
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`Jan. 29, 2013
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`Sheet 3 of 25
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`US 8,363,337 B2
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`N
`
`SS
`
`-
`
`& SN a.
`xN |
`y CN
`o
`g NS s
`s A NY Vy s
`s S
`
`4
`
`s
`
`S
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`Sheet 7 Of 25
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`US 8,363,337 B2
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`AN
`Q X al E. Y
`N N N
`t \ s \\
`s A sY \) S.
`
`s &
`
`s
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`Sheet 9 Of 25
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`[89#
`IZZIG
`
`Z09 | 09
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`//[89
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`W9 "3 || ||
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`Jan. 29, 2013
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`Sheet 13 Of 25
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`US 8,363,337 B2
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`TABLE 1.
`(Embodiment 1)
`fe 4.34 mm, Fno = 2.85, HFOV 33.2 deg.
`Curvature Radius Thickness Material
`Index
`
`Surface #
`
`RG.
`
`O
`1.
`2
`3
`4
`5
`6
`7
`8
`9
`10
`11
`12
`13
`14
`
`Object
`Plano
`Lens l
`1424400 (ASP)
`te -43.791 100 (ASP)
`Ape. Stop
`Plano
`Lens 2
`-15.543700 (ASP)
`4.287000 (ASP)
`-3.112200 (ASP)
`-3.973 100 (ASP)
`-3.011300 (ASP)
`-0-881520 (ASP)
`-2.171820 (ASP)
`1674970 (ASP)
`Plano
`Plano
`Plano
`
`Lens 3
`
`Lens 4
`
`Lens 5
`
`Infinity
`0.562
`-0.010
`0.096
`0.351
`0.559
`0.302
`0.274
`0.790
`0.250
`0.360
`0.700
`0.3OO
`0.334
`
`Plastic
`
`1544
`
`55.9
`
`2.55
`
`Plastic
`
`632
`
`23.4
`
`-5.28
`
`Plastic
`
`1,632
`
`23.4
`
`-26.30
`
`Plastic
`
`1544
`
`55.9
`
`2.03
`
`Plastic
`
`1530
`
`55.8
`
`-1.73
`
`Glass
`
`1517
`
`64.2
`
`Fig.7
`
`R-filter
`
`Image
`
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`Jan. 29, 2013
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`Sheet 15 Of 25
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`US 8,363,337 B2
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`Surface #
`
`Object
`Lens 1
`
`9
`
`12
`13
`14
`
`IR-filter
`
`Image
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`TABLE 3
`(Embodiment 2)
`f = 4.19 mm, Fino - 2.60. HFOV - 34.0 deg.
`Curvature Radius Thickness
`
`Infinity
`0.676
`
`0.258
`
`Plastic
`
`Plastic
`
`Plano
`1571920 (ASP)
`-23.121400 (ASP)
`Plano
`12.150700 (ASP)
`2.853260 (ASP)
`-6.283400 (ASP)
`-12.432900 (ASP)
`-2.500840 (ASP)
`-0.980050 (ASP)
`-11. 77200 (ASP)
`1.469280 (ASP)
`
`1517
`
`64.2
`
`Plano
`Plano
`
`0.283
`
`
`
`Fig.9
`
`Focal
`length
`
`
`
`2.55
`
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`Jan. 29, 2013
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`Sheet 16 of 25
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`US 8,363,337 B2
`
`TABLE 4A
`Aspheric Coefficients
`6
`5
`2
`4
`|
`1
`Surface #
`k = -6.50001E--00-100000E-00-10000OE--00-7.60424E--OOOOOOOOE-HOO
`A4 = | 200906E-01 -6.63627E-02 -8.73985E-02-1559 OE-02 -2.17817E-01
`A6 = -1.823O4E-O 164269E-O 2.18896E-01 9.8594E-02 -14.9415E-0
`
`A8 - 17631E-01-297652E-01-779705E-02-1.12267E-032,42150E-ol
`A10= -1.32426E-0||3.16695E-01-444971E-01-2.20387E-01-2.90.155E-01
`Al2= 3.44944E-02-182173E-01 1.02314E+003.80280E-01 | 1.43366E-01
`Al4=125591E-03441557E-02-6.59333E-01-175174E-ol
`Surface i
`7
`8
`9
`10
`k = 0.00000E+00 2.30246E+00 -3.32916E-00-8.80951E+00
`A4 = -1.48716E-01 2.07 187E-02 -8.800.91 E-02-110587E-02
`A6 = -8.37144E-02 || 4.03194E-02 100182E-01 -2.2986E-02
`
`As = 108256E-01-20414E-0-982521E-02
`A10= -2,95477E-023.06164E-016.46503E-02-104015E-03
`
`A12= . 166616E-02 -1.72754E-01-195080E-02-176243E-04
`A14-
`3.45768E-02 18825OE-03 2.78399E-05
`
`Fig.10A
`
`TABLE 4B
`Aspheric Coefficients
`Surface #
`
`-9.60219E-00
`
`-5.5214OE-02
`
`178677E-02
`
`-6.880 OE-03
`
`153372E-03
`
`- 191127E-04
`
`1.05203E-05
`
`Fig.10B
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
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`Jan. 29, 2013
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`Sheet 17 Of 25
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`US 8,363,337 B2
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`TABLES
`(Embodiment 3)
`f F 4.35 mm, Fno = 2.80. HFOV = 33.2 deg.
`
`Surface #
`
`
`
`Object
`Lens 1
`
`Curvature Radius Thickness Material
`Plano
`Infinity
`142730 (ASP)
`0636
`-18.098000 (ASP)
`0.016
`
`Plastic
`
`
`
`Index
`
`2.45
`
`
`
`
`
`
`
`
`
`
`
`-14976300 (ASP)
`3.368400 (ASP)
`Lens 3 || -5.243800 (ASP)
`-6.016600 (ASP)
`-1.873900 (ASP)
`-0.930010 (ASP)
`24.743600 (ASP)
`1.217630 (ASP)
`Plano
`Plano
`Plano
`
`IR-filter
`
`
`
`0.300
`
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`Jan. 29, 2013
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`Sheet 19 Of 25
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`US 8, 363,337 B2
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`TABLE 7
`(Embodiment 4)
`f = 4.33 mm, Fino a 2.60, HFOV = 33.2 deg.
`Curvature Radius Thickness Material
`Index
`
`Abbe i ?G
`
`Surface #
`
`O
`1.
`2
`3
`4
`5
`6
`7
`8
`9
`10
`11
`12
`13
`14
`
`Object
`Lens 1
`
`|
`
`Ape. Stop
`Lens 2
`
`Lens 3
`
`Lens 4
`
`Lens 5
`
`IR-filter
`
`Image
`
`Plano
`1.396360 (ASP)
`10.488800 (ASP)
`Plano
`10.467100 (ASP)
`2.535670 (ASP)
`- 14.28.5700 (ASP)
`-8.1935.00 (ASP)
`-2.028110 (ASP)
`-1.064940 (ASP)
`9.881400 (ASP)
`1.309360 (ASP)
`Plano
`Plano
`Plano
`
`1544
`
`55.9
`
`Plastic
`
`
`
`55.8
`
`Glass
`
`1517
`
`64.2
`
`0.700
`0.300
`0.414
`
`Fig.13
`
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`Jan. 29, 2013
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`Sheet 21 of 25
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`US 8,363,337 B2
`
`Object
`Ape. Stop
`Lens 1
`
`Lens 2
`
`TABLE 9
`(Embodiment 5)
`f = 4.30 mm, Fno = 2.80. HFOV = 33.5 deg.
`Curvature Radius Thickness Material
`Index
`
`Abbe # fh
`
`Plastic
`
`
`
`2.18
`
`1530
`
`Infinity
`-0.237
`0.607
`0.085
`
`
`
`0500
`0.300
`0.203
`
`Plano
`Plano
`1.257430 (ASP)
`-17.382200 (ASP)
`-5.890300 (ASP)
`5.2973.00 (ASP)
`-4.889000 (ASP)
`-5.833000 (ASP)
`Lens 4 || -2.060770 (ASP)
`-1.254960 (ASP)
`-4. 1498.00 (ASP)
`2.307850 (ASP)
`Plano
`Plano
`Plano
`
`Lens 5
`
`IR-filter
`
`Image
`
`Surface #
`
`
`
`
`
`
`
`O
`11
`12
`13
`14
`
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`Jan. 29, 2013
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`Sheet 23 Of 25
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`US 8,363,337 B2
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`TABLE 1.
`(Embodiment 6)
`f 4.20 mm, Fno - 2.80. HFOV - 34.0 deg.
`
`Surface #
`
`Curvature Radius
`
`1.544
`
`55.9
`
`2.62
`
`21.4
`
`-5.72
`
`55.9
`
`26.23
`
`55.9
`
`5.15
`
`Plastic
`
`1.650
`
`Plastic
`
`1544
`
`0.280
`0.469
`0.323
`0.245
`0.543
`0.636
`0.400
`Plastic
`1544
`0.500 real
`
`Plastic
`
`1544
`
`
`
`Plano
`1.316260 (ASP)
`14.534000 (ASP)
`7.019500 (ASP)
`2.391790 (ASP)
`-2.641690 (ASP)
`-2.3251 10 (ASP)
`-1.5884.00 (ASP)
`-1. 135790 (ASP)
`-4.887700 (ASP)
`2.460040 (ASP)
`Plano
`
`Ape. Stop
`Lens 1
`
`Lens 2
`
`Lens 3
`
`Lens 5
`
`IR-filter
`
`Image
`
`2
`3
`4
`5
`6
`7
`8
`9
`10
`11
`12
`
`13
`14
`
`Plano
`Plano
`
`0.302
`
`Fig.17
`
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`Sheet 25 Of 25
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`US 8,363,337 B2
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`4.34
`f
`285
`Fno
`332
`HFOV
`325
`V1-V2
`V1-(V1+v2+V3)/3) 27
`
`
`
`
`
`
`
`
`
`
`
`(T12/f)*10
`Td/f
`SL/TTL
`
`TABLE 13
`Embodiment Embodiment Embodiment Embodiment Embodiment Embodiment
`2
`4.
`5
`6
`4.19
`4.30
`420
`
`23.0
`
`21.7
`
`230
`
`23.0
`
`11.5
`
`171
`
`153
`
`0.83
`0.95
`
`157
`
`Fig.19
`
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`US 8,363,337 B2
`
`1.
`IMAGING LENS ASSEMBLY
`
`BACKGROUND OF THE INVENTION
`
`1. Field of the Invention
`The present invention relates to an imaging lens assembly,
`and more particularly, to a compact imaging lens assembly
`used in portable electronic devices.
`2. Description of the Prior Art
`In recent years, with the popularity of mobile phone cam
`eras, the demand for compact imaging lenses is increasing,
`and the sensor of a general photographing camera is none
`other than CCD (charge coupled device) or CMOS device
`(Complementary Metal Oxide Semiconductor device). Fur
`thermore, as advanced semiconductor manufacturing tech
`nology has allowed the pixel size of sensors to be reduced and
`the resolution of compact imaging lenses has gradually
`increased, there is an increasing demand for compact imaging
`lenses featuring better image quality.
`A conventional imaging lens assembly for mobile phone
`cameras, such as the one disclosed in U.S. Pat. No. 7,365,920,
`generally comprises four lens elements and an aperture stop
`disposed in front of the four lens elements, wherein two
`spherical-Surface glass lenses are used as the first and second
`lens elements, and being adhered together to form a doublet
`and thereby to correct the chromatic aberration. Such an
`arrangement of optical elements, however, has the following
`disadvantages: (1) the freedom of the system is curtailed due
`to the employment of excess number of spherical-Surface
`glass lenses, thus the total track length of the system cannot be
`reduced easily; (2) the process of making the glass lenses
`adhered together is complicated, posing difficulties in manu
`facture. In addition, a four independent lens elements optical
`system is disclosed by U.S. Pat. No. 7,643,225, comprising
`multiple aspheric lens elements, which effectively shortens
`the total track length and obtains high image quality.
`However, due to the popularity of high standard mobile
`devices such as Smart phones and PDAs (Personal Digital
`Assistant) driving the rapid improvements in high resolution
`and image quality of the current compact imaging lens sys
`tems, conventional four lens elements systems no longer sat
`isfy the higher level camera modules. Furthermore, with the
`current trend for high performance and compact design in
`electronic products, the need for high resolution and high
`performance compact imaging lens assembly is very crucial
`in high level electronics development.
`Therefore, a need exists in the art for an imaging lens
`assembly that features better image quality, maintains a mod
`erate total track length and is applicable to compact portable
`electronic products.
`
`10
`
`15
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`SUMMARY OF THE INVENTION
`
`The present invention provides an imaging lens assembly
`comprising: in order from an object side to an image side: a
`first lens element with positive refractive power having a
`convex object-side Surface; a second lens element with nega
`tive refractive power, a third lens element having a concave
`object-side surface, a fourth lens element with positive
`refractive power having a convex image-side Surface, at least
`one of the object-side and image-side Surfaces thereof being
`aspheric; and a fifth lens element with negative refractive
`power having a concave image-side surface on which at least
`one inflection point is formed; wherein the imaging lens
`assembly further comprises an aperture stop and an electronic
`sensor for image formation, wherein the aperture stop is
`disposed between the imaged object and the second lens
`
`55
`
`60
`
`65
`
`2
`element; and wherein the distance on the optical axis between
`the aperture stop and the electronic sensor is SL, the distance
`on the optical axis between the object-side surface of the first
`lens element and the electronic sensoris TTL, and they satisfy
`the relation: 0.75<SL/TTL31.20.
`According to another aspect of the present invention, an
`imaging lens assembly comprises, in order from an object
`side to an image side: a first lens element with positive refrac
`tive power having a convex object-side Surface; a second lens
`element with negative refractive power having a concave
`image-side Surface; a third lens element having a concave
`object-side Surface and a convex image-side surface; a fourth
`lens element with positive refractive power having a concave
`object-side Surface and a convex image-side Surface, both of
`the object-side and image-side Surfaces thereof being
`aspheric; a fifth lens element with negative refractive power
`having a concave image-side Surface on which at least one
`inflection point is formed, both of the object-side and image
`side Surfaces thereof being aspheric; wherein there is an air
`distance between the first lens element and the second lens
`element; wherein the air distance on the optical axis between
`the first lens element and the second lens element is T12, the
`focallength of the imaging lens assembly is f, and they satisfy
`the relation: 0.05<(T12/f)*10<0.85.
`Such an arrangement of optical elements can reduce the
`size as well as the sensitivity of the imaging lens assembly
`and enables the lens assembly to obtain higher resolution.
`In the present imaging lens assembly, the first lens element
`has positive refractive power so that the total track length of
`the imaging lens assembly can be effectively reduced; the
`second lens element has negative refractive power so that the
`aberration generated from the positive refractive power of the
`first lens element and the chromatic aberration of the system
`can be favorably corrected; the third lens element can have
`either negative or positive refractive power; when the third
`lens element has negative refractive power, the Petzval Sum
`of the system can be corrected effectively and the peripheral
`image plane becomes flatter, when the third lens element has
`positive refractive power, the high order aberration of the
`system can be favorably corrected; the fourth lens element
`with positive refractive power can effectively distribute posi
`tive refractive power contributed by the first lens element in
`order to mitigate the sensitivity of the system; the fifth lens
`element with negative refractive power can place the princi
`pal point of the optical system away from the image plane,
`reducing the total track length in order to maintain a compact
`imaging lens System.
`In the present imaging lens assembly, the first lens element
`may be a bi-convex lens element or a meniscus lens element
`having a convex object-side Surface and a concave image-side
`surface. When the first lens element is a bi-convex lens ele
`ment, the refractive power thereof can be effectively
`enhanced, thus allowing a shortening of the total track length
`of the imaging lens assembly. When the first lens element is a
`meniscus lens element, the astigmatism of the system can be
`corrected more favorably. The second lens element has a
`concave object-side surface so as to favorably extend the back
`focal length of the system, thereby providing Sufficient space
`to accommodate other components. The third lens element
`has a concave object-side Surface so as to facilitate the cor
`rection of the astigmatism and high order aberrations of the
`system. Moreover, the third lens element preferably has a
`concave object-side Surface and a convex image-side surface;
`and the fourth lens element has a convex image-side Surface
`and can effectively reduce the incident angle of the system on
`the electronic sensor and increase the photo sensitivity of the
`system; preferably, the fourth lens element has a concave
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`3
`object-side Surface and a convex image-side Surface, which
`can effectively correct the aberration of the system at the same
`time; the fifth lens element has a concave image-side Surface
`so that the principal point of the system can be away from the
`image plane, and the total track length of the system can be
`reduced, in order to maintain the compact size of the lens
`assembly; preferably, the fifth lens element has a concave
`object-side Surface and a concave image-side surface.
`In the aforementioned imaging lens assembly, the aperture
`stop can be disposed between the imaged object and the first
`lens element or between the first lens element and the second
`lens element. The first lens element provides positive refrac
`tive power, and the aperture stop is disposed near the object
`side of the imaging lens assembly, thereby the total track
`length of the imaging lens assembly can be reduced effec
`tively. The aforementioned arrangement also enables the exit
`pupil of the imaging lens assembly to be positioned far away
`from the image plane, thus light will be projected onto the
`electronic sensor at a nearly perpendicular angle, and this is
`the telecentric feature of the image side. The telecentric fea
`ture is very important to the photosensitive power of the
`current solid-state sensor as it can improve the photosensitiv
`ity of the sensor to reduce the probability of the occurrence of
`shading. Moreover, the fifth lens element is provided with at
`25
`least one inflection point, thereby the angle at which the light
`is projected onto the sensor from the off-axis field can be
`effectively reduced to further correct the off-axis aberrations.
`In addition, when the aperture stop is disposed closer to the
`second lens elements, a wide field of view can be favorably
`achieved. Such stop placement facilitates the correction of the
`distortion and chromatic aberration of magnification, and the
`mitigation of the systems sensitivity. Therefore, in the
`present imaging lens assembly, the aperture stop is placed
`between the imaged object and the second lens element for
`the purpose of achieving a balance between the telecentric
`feature and wide field of view of the imaging lens assembly:
`when the aperture stop is disposed between the imaged object
`and the first lens element, telecentric feature of the system is
`emphasized and the total track length can be shortened; when
`40
`the aperture stop is disposed between the first lens element
`and the second lens element, the wide field of view is empha
`sized and the sensitivity of the system can be effectively
`reduced.
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`US 8,363,337 B2
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`4
`FIG. 6A shows an imaging lens assembly in accordance
`with a sixth embodiment of the present invention.
`FIG. 6B shows the aberration curves of the sixth embodi
`ment of the present invention.
`FIG. 7 is TABLE 1 which lists the optical data of the first
`embodiment.
`FIGS. 8A and 8B are TABLES 2A and 2B which list the
`aspheric surface data of the first embodiment.
`FIG.9 is TABLE3 which lists the optical data of the second
`embodiment.
`FIGS. 10A and 10B are TABLES 4A and 4B which list the
`aspheric Surface data of the second embodiment.
`FIG. 11 is TABLE5 which lists the optical data of the third
`embodiment.
`FIGS. 12A and 12B are TABLES 6A and 6B which list the
`aspheric surface data of the third embodiment.
`FIG. 13 is TABLE 7 which lists the optical data of the
`fourth embodiment.
`FIGS. 14A and 14B are TABLES 8A and 8B which list the
`aspheric surface data of the fourth embodiment.
`FIG. 15 is TABLE9 which lists the optical data of the fifth
`embodiment.
`FIGS. 16A and 16B are TABLES 10A and 1 OB which list
`the aspheric surface data of the fifth embodiment.
`FIG. 17 is TABLE 11 which lists the optical data of the
`sixth embodiment.
`FIGS. 18A and 18B are TABLES 12A and 12B which list
`the aspheric surface data of the sixth embodiment.
`FIG. 19 is TABLE 13 which lists the data of the respective
`embodiments resulting from the equations.
`
`DETAILED DESCRIPTION OF THE PREFERRED
`EMBODIMENTS
`
`The present invention provides an imaging lens assembly
`comprising, in order from the object side to the image side: a
`first lens element with positive refractive power having a
`convex object-side Surface; a second lens element with nega
`tive refractive power; a third lens element having a concave
`object-side surface; and a fourth lens element with positive
`refractive power having a convex image-side Surface, at least
`one of the object-side and image-side Surfaces thereof being
`aspheric ; a fifth lens element with negative refractive power
`having a concave image-side Surface on which at least one
`inflection point is formed; wherein the imaging lens assembly
`further comprises an aperture stop and an electronic sensor
`for image formation; wherein the aperture stop is disposed
`between the imaged object and the second lens element; and
`wherein the distance on the optical axis between the aperture
`stop and the electronic sensor is SL, the distance on the
`optical axis between the object-side surface of the first lens
`element and the electronic sensor is TTL, and they satisfy the
`relation: 0.75<SL/TTL-120.
`When the aforementioned imaging lens assembly satisfies
`the above relation: 0.75-SL/TTL<1.20, the imaging lens
`assembly can obtain a good balance between the telecentric
`feature and wide field of view; preferably, the aperture stop is
`disposed between the first lens element and the second lens
`element, and they satisfy the relation: 0.75<SL/TTL<0.92.
`In the aforementioned imaging lens assembly, it is prefer
`able that the second lens element has a concave image-side
`surface so as to effectively increase the back focal distance in
`order to obtain enough space for additional components; pref
`erably, the fourth lens element has a concave object-side
`Surface; wherein a meniscus fourth lens element having a
`concave object-side Surface and a convex image-side Surface
`can favorably correct the aberration of the system; preferably,
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1A shows an imaging lens assembly in accordance
`with a first embodiment of the present invention.
`FIG. 1B shows the aberration curves of the first embodi
`ment of the present invention.
`FIG. 2A shows an imaging lens assembly in accordance
`with a second embodiment of the present invention.
`FIG.2B shows the aberration curves of the second embodi
`ment of the present invention.
`FIG. 3A shows an imaging lens assembly in accordance
`with a third embodiment of the present invention.
`FIG. 3B shows the aberration curves of the third embodi
`ment of the present invention.
`FIG. 4A shows an imaging lens assembly in accordance
`with a fourth embodiment of the present invention.
`FIG. 4B shows the aberration curves of the fourth embodi
`ment of the present invention.
`FIG. 5A shows an imaging lens assembly in accordance
`with a fifth embodiment of the present invention.
`FIG. 5B shows the aberration curves of the fifth embodi
`ment of the present invention.
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`US 8,363,337 B2
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`the fifth lens element has a concave object-side surface;
`wherein a bi-concave fifth lens element can place the princi
`pal point of the optical system further away from the image
`plane, which reduces the total track length of the system in
`order to stay compact.
`In the aforementioned imaging lens assembly, it is prefer
`able that the object-side and image-side surfaces of the fifth
`lens elements are aspheric. Aspheric Surfaces can be easily
`made into non-spherical profiles, allowing more design
`parameter freedom which can be used to reduce aberrations
`and the number of the lens elements, so that the total track
`length of the imaging lens assembly can be effectively
`reduced; preferably, the fifth lens element is made of plastic
`material. Plastic material is favorable for the reduction in the
`weight of the lens assembly and also in the production cost.
`In the aforementioned imaging lens assembly, the focal
`length of the first lens element is fl, the focal length of the
`imaging lens assembly is f, and they preferably satisfy the
`relation: 0.40<f1/f-0.80. When the above relation is satisfied,
`the refractive power of the first lens element is more balanced
`so that the total track length of the system can be effectively
`controlled to keep the imaging lens assembly compact. The
`above relation also prevents the high order spherical aberra
`tion from becoming too large, so that the image quality can be
`improved. And preferably they satisfy the relation: 0.50<f1/
`f:30.70.
`In the aforementioned imaging lens assembly, the thick
`ness on the optical axis of the second lens element is CT2, the
`focal length of the imaging lens assembly is f, and they
`preferably satisfy the relation: 0.30<(CT2/f)*10<1.00. When
`30
`the above relation is satisfied, the thickness of the second lens
`element is appropriate when trying to achieve a good balance
`between the manufacturing yield and the correction of the
`system aberration.
`In the aforementioned imaging lens assembly, the Abbe
`number of the first lens element is V1, the Abbenumber of the
`second lens element is V2, and they preferably satisfy the
`relation: 25.0<V1-V2<45.0. The above relation facilitates
`the correction of the chromatic aberration of the imaging lens
`assembly. And it will be more preferable that V1 and V2
`40
`satisfy the relation: 30.0<V1-V2<42.0.
`In the aforementioned imaging lens assembly, the radius of
`curvature of the object-side surface of the first lens element is
`R1, the focallength of the imaging lens assembly is f, and they
`preferably satisfy the relation: 0.25<R1/f-0.45. When the
`above relation is satisfied, the first lens element is provided
`with sufficient positive refractive power while preventing
`high order aberration from becoming too large.
`In the aforementioned imaging lens assembly, the focal
`length of the first lens element is fl, the focal length of the
`fourth lens element is fa, and they preferably satisfy the
`relation: 0.80<f1/f4<1.40. When the above relation is satis
`fied, the distribution of refractive power from the first lens
`element and the fourth lens element is more balanced, which
`reduces the sensitivity of the system and the generation of 55
`aberration.
`In the aforementioned imaging lens assembly, with air
`distance between the first lens element and the second lens
`element, the distance on the optical axis between the first and
`second lens elements is T12, the focal length of the imaging
`lens assembly is f, and they preferably satisfy the relation:
`0.05<(T12/f)*10<0.85. When the above relation is satisfied,
`the distance on the optical axis between the first lens element
`and the second lens element is more appropriate, which
`avoids the difficulties of lens element insertion due to overly
`tight spacing or maintaining compact size due to overly large
`spacing.
`
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`6
`In the aforementioned imaging lens assembly, the Abbe
`number of the first lens element is V1, the Abbe number of the
`second lens element is V2, the Abbe number of the third lens
`element is V3, and they preferably satisfy the relation:
`15.0<V1-((V1+V2+V3)/3)<30.0. When the above relation is
`satisfied, the correction of the chromatic aberration of the
`imaging lens assembly is even more favorable in order to
`increase the resolution of the system.
`In the aforementioned imaging lens assembly, the distance
`on the optical axis between the object-side surface of the first
`lens element and the image-side surface of the fifth lens
`element is Tod, the focal length of the imaging lens assembly
`is f, and they preferably satisfy the relation: 0.70<Td/f-1.00.
`When the above relation is satisfied, the lens elements are
`placed closer togetherin order to maintain the compact size of
`the imaging lens system.
`In the aforementioned imaging lens assembly, the distance
`on the optical axis between the object-side surface of the first
`lens element and the electronic sensor is TTL, half of the
`diagonal length of the effective pixel area of the electronic
`sensor is ImgH, and they preferably satisfy the relation: TTL/
`ImgH-1.95. The above relation enables the imaging lens
`assembly to maintain a compact form so that it can be
`installed in compact portable electronic products.
`The present invention provides another imaging lens
`assembly comprising, in order from the object side to the
`image side: a first lens element with positive refractive power
`having a convex object-side Surface; a second lens element
`with negative refractive power having a concave image-side
`Surface; a third lens element having a concave object-side
`surface and a convex image-side surface; a fourth lens ele
`ment with positive refractive power having a concave object
`side Surface and a convex image-side Surface, both of the
`object-side and image-side surfaces thereof being aspheric;
`and a fifth lens element with negative refractive power having
`a concave image-side Surface on which at least one inflection
`point is formed, both of the object-side and image-side Sur
`faces thereof being aspheric; wherein there is an air distance
`between the first lens element and the second lens element,
`and the distance on the optical axis between the first lens
`element and the second lens element is T12, the focal length
`of the imaging lens assembly is f, and they satisfy the relation:
`0.05<(T12/f)*10<0.85.
`When the aforementioned imaging lens assembly satisfies
`the relation: 0.05<(T12/f)*10<0.85, the air distance on the
`optical axis between the first lens element and the second lens
`element is more appropriate for avoiding difficulties lens
`element insertions due to overly tight spacing or maintaining
`the compact size of the lens assembly due to overly large
`spacing.
`In the aforementioned imaging lens assembly, it is prefer
`able that the fifth lens element has a concave image-side
`surface, which makes the fifth lens element a bi-concave lens
`element, so as to move the principal point of the optical
`system further away from the image plane, in order to reduce
`the total track length of the system and maintain the compact
`size of the system.
`In the aforementioned imaging lens assembly, the fifth lens
`element is made of plastic material. Plastic material is favor
`able for the reduction in weight of the le