6,031,670
`[11] Patent Number:
`[19]
`United States Patent
`
`Inoue
`[45] Date of Patent:
`*Feb. 29, 2000
`
`US006031670A
`
`54 WIDE-ANGLE LENS
`l
`
`[
`
`[75]
`
`Inventor: Toshiyuki Inoue, Nagano, Japan
`.
`_
`_
`[73] ASSIgnee: Sankyo selkl Mfg- C09 Ltd”
`Nagano'ken’ Japan
`This patent issued on a continued pros-
`ecution application filed under 37 CFR
`1.53(d), and is subject to the twenty year
`patent
`term provisions of 35 USO
`154(a)(2).
`
`[*] Notice:
`
`This patent is subject to a terminal dis-
`claimer.
`
`[21] Appl. No.: 08/757,192
`.
`.
`Flled‘
`
`[22]
`
`N0“ 27’ 1996
`Related US. Application Data
`
`[63]
`
`[30]
`
`Continuation—in—part of application No. 08/590,725, Jan. 24,
`1996, abandoned, which is a continuation of application No.
`08/251,623, May 31, 1994, abandoned, which is a continu—
`nglngf application No. 07/738,854, Jul. 31, 1994, aban—
`.
`Foreign Application Priority Data
`
`Japan .................................... 2—225975
`[JP]
`Aug. 28, 1990
`[51]
`Int. Cl.7 ..................................................... G02B 13/18
`[52] US. Cl.
`........................... 359/717; 359/739; 359/793
`[58] Field of Search ..................................... 359/642—648,
`359/664, 670, 708, 713-717, 744—753,
`793
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`3,511,558
`4,593,984
`4,674,844
`4,702,569
`4,720,183
`4,747,675
`$23333:
`’
`’
`4,865,435
`4,896,217
`4,906,078
`5,005,955
`5,508,848
`
`
`
`5/1970 Uberha en .............................. 359/739
`8
`6/1986 Kimura et al.
`359/717
`6/1987 Nishioka etal.
`359/708
`..
`10/1987 Hercado etal.
`359/793
`1/1988 Dilworth ................................. 359/643
`5/1988 Nagler ..................................... 359/643
`:/13:: 5:13“) et la].
`323/33:
`/
`a 6 et a'
`/
`9/1989 Cho ...................
`359/716
`1/1990 Hiyazawa et al.
`...................... 348/342
`3/1990 Iuabata et al.
`.......................... 359/676
`4/1991 Ohshita ..........
`359/676
`
`4/1996 Inoue ...................................... 359/717
`
`
`
`FOREIGN PATENT DOCUMENTS
`
`3346785
`93116
`247213
`91618
`
`6/1982 Germany ............................... 359/708
`7/1980
`Japan
`359/717
`12/1985
`Japan
`359/717
`5/1986
`Japan
`
`.. 359/717
`
`55511
`
`3/1988
`
`Japan ..................................... 359/793
`
`Primary Examiner—Thong Nguyen
`Attorney, Agent, or Firm—McAulay Nissen Goldberg Kiel
`& Hand, LLP
`
`[57]
`
`ABSTRACT
`
`The present invention is directed toward a Wide-angle lens.
`Because of a small quantity (two) of lens elements, the
`Wide-angle lens facilitates size and weight reduction and
`permits low-cost manufacture. The lens is made from
`plastic, Which permits further costreduction. The lens is
`particularly useful When employed in CCD cameras.
`
`2,889,745
`
`6/1959 Hayes et al.
`
`............................ 359/793
`
`15 Claims, 7 Drawing Sheets
`
`
`
`Panasonic Exhibit 1007 Page 1 of 12
`
`

`

`US. Patent
`
`Feb. 29, 2000
`
`Sheet 1 0f 7
`
`6,031,670
`
`
`
`FIG.2
`
`FIG.3
`
`Panasonic Exhibit 1007 Page 2 of 12
`
`
`

`

`US. Patent
`
`Feb. 29, 2000
`
`Sheet 2 0f 7
`
`6,031,670
`
`
`
`FIG.4
`
`
`
`laurla”
`
`32
`
`FIGS
`
`Panasonic Exhibit 1007 Page 3 of 12
`
`
`

`

`US. Patent
`
`Feb. 29, 2000
`
`Sheet 3 0f 7
`
`6,031,670
`
`SPHERICAL
`ABERRATION
`
`AST'GMAT'SM
`
`FIELD
`CURVATURE
`
`'
`1
`PK-SC
`
`:
`s— "1
`1‘
`l
`
`0. 2 mm
`
`0 2 mm
`
`20%
`
`y:
`
`y = 1.73
`
`y = 2.43
`
`a— LINE
`
`COMA ABERRATION
`
`F | G. 6
`
`Panasonic Exhibit 1007 Page 4 of 12
`
`

`

`US. Patent
`
`Feb. 29, 2000
`
`Sheet 4 0f 7
`
`6,031,670
`
`SPHERICAL
`ABERRATION
`
`AST'GMAT'SM
`
`FIELD
`CURVATURE
`
` SA
`
`i
`i
`
`0.2 mm
`
`0.2 mm
`
`20%
`
`oz - LINE
`
`0.1
`
`0.1 —?l0.1
`
`COMA ABERRATION
`
`F | G. 7
`
`Panasonic Exhibit 1007 Page 5 of 12
`
`\ f
`
`Iii
`
`-x,SC
`
`

`

`US. Patent
`
`Feb. 29, 2000
`
`Sheet 5 0f 7
`
`6,031,670
`
`SPHERICAL
`ABERRATION
`
`AST'GMAT'SM
`
`FIELD
`CURVATURE
`
`m
`
`0.2 mm
`
`————— 20%
`
`y = 2.45
`
`
`
`SA
`
`'~\,SC
`
`0.2 mm
`
`y = 0
`
`\ a - LINE
`
`
`
`0.1
`
`0.1
`
`0.1
`
`>
`
`
`
`COMA ABERRATION
`
`4
`
`FIGS
`
`Panasonic Exhibit 1007 Page 6 of 12
`
`

`

`US. Patent
`
`Feb. 29, 2000
`
`Sheet 6 0f 7
`
`6,031,670
`
`SPHERICAL
`ABERRATION
`
`AST'GMAT'SM
`
`FIELD
`CURVATURE
`
`
`
`0.2 mm
`
`0.2 mm —— 20%
`
`y=o
`
`y=1.45
`
`y=2-69
`
`0L - LINE
`
`0.1
`
`_
`
`0.1
`
`0.1
`
`COMA ABERRATION
`
`F I G. 9
`
`Panasonic Exhibit 1007 Page 7 of 12
`
`

`

`US. Patent
`
`Feb. 29, 2000
`
`Sheet 7 0f 7
`
`6,031,670
`
`SPHERICAL
`ABERRATION
`
`AST'GMAT'SM
`
`FIELD
`CURVATU RE
`
` r~,"SC
`
`m
`
`‘f "S
`i
`i
`i
`i
`l
`l
`i
`i
`i
`
`0.2 mm —-——— 0.2mm
`
`20%
`
`y=0
`
`y=1.45
`
`y=2-67
`
`0c- LINE
`
`0.1
`
`0.1
`
`0.1
`
`COMA ABERRATION
`
`FIG.1O
`
`Panasonic Exhibit 1007 Page 8 of 12
`
`

`

`1
`WIDE-ANGLE LENS
`
`6,031,670
`
`2
`
`This is a continuation-in-part of application Ser. No.
`08/590,725, filed Jan. 24, 1996, now abandoned, which in
`turn, was a continuation of application Ser. No. 08/251,623,
`filed May 31, 1994, now abandoned, which, in turn, was
`continuation of application Ser. No. 07/738,854, filed Jul.
`31, 1991, now abandoned.
`
`BACKGROUND OF THE INVENTION
`
`1. Field of the Invention
`
`The invention relates to a wide-angle lens. More
`particularly, the invention relates to a wide angle lens having
`particular application to CCD-type cameras.
`2. Background Prior Art
`Lately, small-sized wide-angle lenses have become
`increasingly used in 1/2- and 1/3-inch CCD cameras which
`have recently been put into use.
`Five-element wide-angle lenses are a common known
`type of such small-sized lenses.
`However, such wide-angle lenses have practical limita-
`tions in size, weight and cost because they employ as many
`as five lens elements.
`
`OBJECT OF THE INVENTION
`
`The present invention was designed to solve the problems
`mentioned above. Its primary object, therefore, is to provide
`a novel wide-angle lens which can easily be decreased in
`size and weight and manufactured at a low cost.
`For a better understanding of the present invention, ref-
`erence is made to the following description and accompa-
`nying drawings while the scope of the invention will be
`pointed out in the appended claims.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIGS. 1 to 5 show the lens construction of corresponding
`embodiments 1 to 5.
`
`FIGS. 6 to 10 show aberrations of embodiments 1 to 5,
`respectively.
`
`DESCRIPTION OF INVENTION AND
`PREFERRED EMBODIMENTS
`
`The wide-angle lens system 20 according to the invention
`comprises a first lens element and a second lens element
`which are located on object and image (picture) sides,
`respectively. In the drawings, a first lens element is desig-
`nated as 26 and a second lens element is designated as 28.
`The first
`lens element 26 is a meniscus type having a
`negative refractive power and the second lens element 28 is
`a two sided convex type having a positive refractive power,
`one or more of lens surfaces of lens elements 26, 28 being
`made aspherical.
`The wide-angel lens system 20 can be used in 1/2- and
`1/3-inch CCD cameras, for example.
`The quantity of the component lens element of the wide-
`angle lens system 20 according to the present invention is
`thereby reduced to two. In order to secure high performance
`with the small quantity of lens elements, however, they are
`made aspherical.
`the
`In order to make its performances more effective,
`wide-angle lens according to the invention is made to satisfy
`the following requirements.
`
`|f1|<D
`
`(1)
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`4s
`
`50
`
`55
`
`60
`
`65
`
`wherein (fl) is the focal length of the first lens element 26
`and D is the distance between the principal points of the first
`and second lens elements 26, 28.
`the wide-angle lens
`When satisfying requirement (1),
`system 20 permits its back-focus to be made two times
`longer despite its short focal length.
`
`—1.5<r2/{(n1—1)f1}<—0.5
`
`(2)
`
`wherein (r2) is the curvature radius of the image-side surface
`of the first lens element 26 and (n1) is the refractive index of
`the material from which the first
`lens element 26 was
`constructed.
`
`the wide-angle lens
`When satisfying requirement (2),
`system 20 permits astigmatism to become positively large or
`negatively large above the upper limit of requirement (2) or
`below its lower limit respectively.
`
`— 10 <K4<— 1
`
`(3)
`
`wherein K4 is the conical reflection constant when the
`image-side surface of the second lens element 28 is aspheri-
`cal.
`
`the wide-angle lens
`When satisfying requirement (3),
`system 20 permits spherical aberration to be well corrected.
`Namely, spherical aberration becomes negatively large or
`positively large above the upper limit of requirement (3) or
`below its lower limit respectively.
`
`—2<f1/f2<—1
`
`(4)
`
`wherein (f2) is the focal length of the second lens element
`28.
`
`the wide-angle lens
`When satisfying requirement (4),
`system 20 permits field curvature to be well corrected.
`Namely, field curvature becomes positive or negative above
`the upper limit of requirement (4) or below its lower limit
`respectively When not satisfying requirement (4), its lowers
`performance of the lens system 20.
`The wide-angle lens system 20 according to the invention
`permits achromatism even when its first and second lens
`elements 26, 28 are made from the same material.
`When the first and second lens elements 26, 28 are made
`from acryl (PMMA), the wide-angle lens system 20 permits
`material and manufacturing costs to be reduced further.
`The invention will be more fully understood by describing
`five embodiments as follows.
`It is assumed that the first lens surface counted from the
`
`object side (including lens surface, diaphragm and CCD
`cover glass) has a curvature radius r,- (i=1—7) and a distance
`di (i=1—5) is given between the (i)-th and (i+1)-th surfaces
`on the optical axis. Formula j=1, 2 represent the first and
`second lens elements respectively, j=3 the above mentioned
`cover glass, (nj) refractive index of the material of the lens
`elements and cover glass j=1—3.
`Aspherical surface of the lens elements of the wide-angle
`lens is obtained by revolving curve:
`
`X = [Griz/{1+ \fl — (K+ 1JCZW}]+A4Y4 +A6Y6
`
`about the optical axis (X) with optically-axial coordinate and
`the coordinate orthogonal therewith given symbols X and Y
`respectively, optically-axial curvature C, conical reflection
`constant K, A4, A6 quarternary and hexanary aspherical
`coefficients, and its configuration is specified by giving
`conical refiectin constant K ans aspherical coefficients A4,
`A6.
`
`Panasonic Exhibit 1007 Page 9 of 12
`
`

`

`3
`Embodiment 1
`
`4
`Embodiment 3
`
`6,031,670
`
`f=3.3 mm, F/No=1.8
`
`f=3.3 mm, F/No=1.8
`
`Picture size: 1/3 inch gdiagonal distance: 5.5 mm
`r.I
`d.
`I
`40.00
`1.00
`3.16
`8.50
`4.38
`2.50
`—5.03
`0.00
`(Diaphragm)
`6.22
`00
`0.70
`co
`
`1
`
`2
`
`3
`
`>—‘.
`
`1
`2
`3
`4
`5
`6
`7
`
`Picture size: 1/3 inch diagonal distance: 5.5 mm
`
`i
`1
`2
`3
`4
`5
`6
`7
`
`ri
`20.00
`3.11
`5.16
`—4.64
`(Diaphragm)
`00
`00
`
`di
`1.00
`8.50
`2.50
`0.00
`6.15
`0.80
`
`j
`1
`
`2
`
`3
`
`nj
`1.5168
`
`1.5168
`
`1.5168
`
`10
`
`j
`1.491
`
`1.491
`
`1.5168
`
`15
`
`Aspherical surface: r4
`
`K=—4.16934
`
`A4=2.19540x10-3, A6=2.19540x10‘3
`f1=—7.04, f2=5.22, D=8.68, r2/{(n1—1)f1}=—0.91
`fl/f2=—1.35
`The first and second lens elements 26, 28 were made from
`PMMA (acryl). The configuration of the lens and associated
`light paths according to the first embodiment are illustrated
`in FIG. 1 and the aberrations of the first embodiment are
`illustrated in FIG. 6. The coma aberration shown therein is
`
`obtained in connection with (d)- line.
`
`Embodiment 2
`
`f=5.0 mm, F/No=1.8
`
`Picture size: 1/2 inch gdiagonal distance: 8.0 mm
`
`i
`1
`2
`3
`4
`5
`6
`7
`
`ri
`100.00
`4.32
`7.32
`—7.05
`(Diaphragm)
`00
`co
`
`di
`1.00
`12.00
`3.00
`0.00
`10.58
`0.70
`
`j
`1
`
`2
`
`3
`
`nj
`1.491
`
`1.491
`
`1.5168
`
`50
`
`20
`
`25
`
`30
`
`35
`
`40
`
`4s
`
`Aspherical surface: r3
`K=—1.76816
`
`A4=2.20288><10‘5, A6=—6.86197><10'7
`Aspherical surface: r4
`K=—2.83668
`
`A4=—6.15852><10‘6, A6=2.98626><10'7
`f1=—7.28, f2=5.18, D=9.33, r2/{(n1—1)f1}=—0.83
`fl/f2=—1.41
`The first and second lens elements 26, 28 and cover glass
`32 were made from the same material (BK7). The configu-
`ration of the lens and associated light paths according to the
`third embodiment are illustrated in FIG. 3 and the aberra-
`tions of the third embodiment are illustrated in FIG. 8. The
`coma aberration shown therein is obtained in connection
`
`with (d)- line.
`
`Embodiment 4
`
`f=5.0 mm, F/No=3.5
`
`Picture size: 1/3 inch diagonal distance: 5.5 mm
`
`i
`1
`2
`3
`4
`5
`6
`7
`
`ri
`16.500
`2.663
`5.050
`—5.328
`(Diaphragm)
`oo
`oo
`
`di
`1.500
`6.000
`2.000
`0.200
`5.875
`4.600
`
`j
`1
`
`2
`
`3
`
`nj
`1.49091
`
`1.49091
`
`1.51680
`
`Aspherical surface: r3
`K=—2.27678
`
`A4=0, A6:
`Aspherical surface: r4
`K=—9.5
`
`A4=0, A6=0
`f1=—6.708, f2=5.639, D=6.900, rZ/{(n1—1)fl}=—0.809
`fl/f2=—1.190
`The first and second lens elements 26, 28 were made from
`PMMA (acryl). The configuration of the lens and associated
`light paths according to the fourth embodiment are illus-
`trated in FIG. 4 and the aberrations of the fourth embodi-
`ment are illustrated in FIG. 9. The coma aberration shown
`
`Aspherical surface: r4
`
`K=—2.70060
`
`A4=6.15920><10'4, A6=4.25890x10'6
`
`f1=—9.21, f2=7.84, D=13.16, r2/{(n1—1f1}=—0.95
`fl/f2=—1.17
`The first and second lens elements 26, 28 were made from
`PMMA (acryl). The configuration of the lens and associated
`light paths according to the second embodiment are illus-
`trated in FIG. 2 and the aberrations of the second embodi-
`ment are illustrated in FIG. 7. The coma aberration shown
`
`55
`
`60
`
`65
`
`therein is obtained in connection with (d)- line.
`
`therein is obtained in connection with (d) - line.
`
`Panasonic Exhibit 1007 Page 10 of 12
`
`

`

`6,031,670
`
`5
`Embodiment 5
`
`f=5.0 mm, F/No=2.5
`
`Picture size: 1/3 inch gdiagonal distance: 5.5 mm
`
`i
`1
`2
`3
`4
`5
`6
`7
`
`ri
`21.000
`2.805
`8.403
`—4.382
`(Diaphragm)
`co
`co
`
`di
`1.500
`6.800
`2.000
`0.00
`9.386
`0.800
`
`j
`1
`
`2
`
`3
`
`nj
`1.49091
`
`1.49091
`
`1.51680
`
`Aspherical surface: r3
`K=—5.54774
`
`A4=0, A6=0
`Aspherical surface: r4
`K=—1.2
`
`A4=0, A6=0
`f1=—6.779, f2=6.095, D=7.900, r2/{(n1—1)f1}=—0.843
`fl/f2=—1.112
`The first and second lens elements 26, 28 were made from
`PMMA (acryl). The configuration of the lens and associated
`light paths according to the fifth embodiment are illustrated
`in FIG. 5 and the aberrations of the fifth embodiment are
`illustrated in FIG. 10. The coma aberration shown therein is
`
`obtained in connection with (d) - line.
`FIGS. 1 through 5 show the layout of the lens elements of
`the wide-angle lens system of the Embodiments 1 through 5
`and light paths therein. In FIGS. 1 through 5 numeral 26 is
`a first lens element, 28 a second lens element, 30 a dia-
`phragm and 32 a cover glass.
`As is clear from the drawings, all the embodiments show
`good performances.
`In the aberration diagrams, consideration is given to the
`presence of the cover glass.
`While the foregoing description and drawings represent
`the preferred embodiments of the present invention, it will
`be obvious to those skilled in the art that various changes
`and modifications may be made therein without departing
`from the true spirit and scope of the present invention.
`What is claimed is:
`
`1. A wide angle lens system comprising:
`a first lens element and a second lens element which are
`
`located on the object side and image side respectively,
`said first lens element being of a meniscus type having
`a negative refractive power and said second lens ele-
`ment being of a two-sided convex type having a
`positive refractive power, at least one surface of said
`lens elements being aspherical, said wide angle lens
`system having no more than two lens elements and
`wherein
`
`|f1|<D;
`[—1.5<r2/{(n1—1)f1}<—0.5; and
`—2<f1/f2§i1]
`—1.5<r2/ {(n1—1)f1}—0.5; and
`—2<f1/f2<—1
`where (fl) is the focal length of the first lens element and D
`is the distance between a back principal point of the first lens
`element and a front principal point of the second lens
`element, where (r2) is the curvature radius of the image-side
`surface of the first lens element, where (n1) is the refractive
`
`6
`index of the material of the first lens element, and where (f2)
`is the focal length of the second lens element.
`2. The wide angle lens system of claim 1, wherein
`
`—10<K4<—1
`
`where (K4) is the conical reflection constant when the
`image-side surface of the second lens element
`is
`aspherical.
`3. The wide angle lens system of claim 2, wherein said
`lens elements are made of plastic.
`4. The wide angle lens system of claim 3, wherein said
`lens elements are made from acryl.
`5. The wide angle lens system of claim 1, wherein said
`lens elements are made of plastic.
`6. The wide angle lens system of claim 5, wherein said
`lens elements are made from acryl.
`7. The wide angle lens system of claim 5, including a
`diaphragm and a cover glass for a CCD layer on the image
`side, said diaphragm being between said second lens ele-
`ment and said cover glass.
`8. The wide angle lens system of claim 1, including a
`diaphragm and a cover glass for a CCD layer on the image
`side, said diaphragm being between said second lens ele-
`ment and said cover glass.
`9. The wide angle lens system of claim 8, wherein said
`first and second lens elements are constructed of the same
`
`material as said cover glass.
`10.
`In a camera having a wide angle lens system, a
`diaphragm and a plane surface for forming an image, the
`improvement comprising:
`that said wide angle lens system comprises:
`a first lens element and a second lens element which are
`
`located on the object side and image side respectively,
`said first lens element being of a meniscus type having
`a negative refractive power and said second lens ele-
`ment being of a two-sided convex type having a
`positive refractive power, at least one surface of said
`lens elements being aspherical, said wide angle lens
`system having no more than two lens elements and
`wherein
`
`|f1|<D;
`—1.5<r2/{(n1—1)f1}<—0.5; and
`—2<f1/f2<—1
`where (fl) is the focal length of the first lens element and D
`is the distance between a back principal point of the first lens
`element and a front principal point of the second lens
`element, where (r2) is the curvature radius of the image-side
`surface of the first lens element, where (n1) is the refractive
`index of the material of the first lens element, and where (f2)
`is the focal length of the second lens element.
`11. The camera of claim 1 wherein said camera is of the
`
`CCD type and wherein a cover glass for CCD elements is
`arranged on the image side, said diaphragm being disposed
`between said second element and said cover glass.
`12. The camera of claim 11 wherein said first and second
`elements are constructed of the same material as said cover
`
`glass.
`13. The camera of claim 1 wherein said first and second
`
`elements are made of plastic.
`14. The camera of claim 10 wherein
`
`—10<K4<—1
`
`where K4 is a conical reflection constant when the
`image-side surface of said second lens element
`is
`aspherical.
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`4s
`
`50
`
`55
`
`60
`
`65
`
`Panasonic Exhibit 1007 Page 11 of 12
`
`

`

`6,031,670
`
`7
`In a camera having a wide angle lens system, a
`15.
`diaphragm and a plane surface for forming an image, the
`improvement comprising:
`that said wide angle lens system has a first lens element
`and a second lens element which are located on an 5
`
`object side and image side respectively, said first lens
`element being of a meniscus type having a negative
`refractive power and said second lens element being of
`a two-sided convex type having a positive refractive
`power, at least one surface of said lens elements being 10
`aspherical wherein
`
`-1-5<r2/{(n1-1)f1}<-0-5
`
`8
`
`wherein (r2) is the curvature radius of the image side
`surface of the first lens element, (fl) is the focal length
`of the first lens element and (n1) is the refractive index
`of the material of the first lens element.
`
`*
`
`*
`
`*
`
`*
`
`*
`
`Panasonic Exhibit 1007 Page 12 of 12
`
`