JPH03251808A - Read lens for scanner - Google Patents

Abstract

PURPOSE:To obtain the read lens for the scanner which has a wide field angle, high contrast, and high aperture efficiency and is bright by arranging 1st - 5th groups in order from the object side to the image side and arranging a stop between the 2nd and 3rd groups. CONSTITUTION:The 1st - 5th groups are arranged in order from the object side to the image side and the stop 15 is arranged between the 2nd and 3rd groups to obtain five-group, seven-element constitution. The 1st group consists of a positive lens 10 and a negative lens 12, the 2nd group consists of a meniscus lens 14, and the 3rd group consists of a meniscus lens 16; and the 4th group consists of a negative lens 18 and a positive lens 20, and the 5th group is a lens 22 which is parallel plane glass and serves as cover glass for a photodetection surface. The stop 15 is arranged between the lenses 14 and 16. Further, the 1st, 5th, 7th, and 8th lens surfaces which are counted from the object side are aspherical surfaces, whose cone constants K are so set that -0.005<K1<0.0, 0.0<K5<0.03, -0.03<K7<0.0, and 0.0<K8<7.0 hold. Consequently, the color division of an image plane is suppressed and a specific comatic flare can be suppressed.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a reading lens for a scanner.

[Prior art] A reduced image of a document is formed on a solid-state image sensor such as a CCD,
2. Description of the Related Art Document reading, which scans a document and reads a document image, is known in connection with image scanners, facsimile machines, digital copying machines, and the like.

A scanner reading lens is a lens for forming a reduced image of a document on a solid-state image sensor during the above-described document reading.

Reading lenses for scanners are required to have a wide angle of view with a small object-to-image distance in order to make document reading devices more compact, and also to be large in diameter and bright in order to speed up document reading. Something is required.

Furthermore, in view of the fact that the pixel size of solid-state image sensors has become smaller in recent years, high-resolution reading lenses are also required for scanners in order to enable high-resolution reading that takes advantage of the capabilities of solid-state image sensors. . For example, in the case of a reading device using a CCD with a pixel size of 7 Atm, the reading lens for the scanner has a 71.4
A resolution of 1/mm is required, and high contrast is required for the spatial frequency over the entire area of the light-receiving surface.

Topobon type lenses have been known as lenses suitable for wide angles of view. The tobogon type has a flat radial image surface.

From this point of view, a tobogon type scanner reading lens has been proposed (for example, Japanese Patent Application Laid-Open No. 63-75721
No. 64-23215).

[Problems to be Solved by the Invention] However, on the other hand, the tobogon type lens has the problem of lacking brightness, making it difficult to meet the demand for faster document reading. There is also the problem that color splitting on the image plane increases as the angle of view becomes wider, resulting in a decrease in contrast.

The present invention was made in view of the above-mentioned circumstances, and
The objective is to provide a new reading lens for scanners that is based on a tobogon type lens and has a bright FNo. of 3, a wide angle of view, and excellent resolution.

[Means to solve problems] The present invention will be explained below.

The scanner reading lens of the present invention is a "document reading lens used with reduction magnification", and has first to fifth groups arranged sequentially from the object side to the image side, and the second and third groups.
It is composed of 7 elements in 5 groups with an aperture between the groups.

The basic structure of the lenses of claims 1 to 5 is the same.

That is, as shown in FIG. 1, the "first group" is composed of the second lens 12, which is a positive lens, and the second lens 12, which is a negative lens cemented to the image side thereof. The "second group" is the third lens 14, which is a meniscus lens with a convex surface facing the object side. The "third group" is the fourth lens 16, which is a meniscus lens with a convex surface facing the image side. The "fourth group" is composed of the fifth lens 18, which is a negative lens, and the sixth lens 20, which is a positive lens cemented to the image side of the fifth lens 18. The "fifth group" is the seventh lens 22 which is a parallel plane glass, and specifically is a cover glass of the light receiving surface of the solid-state image sensor.

A diaphragm 15 is provided between the third lens 14 forming the second group and the fourth lens 16 forming the third group.

Furthermore, the lenses of claims 1 to 5 have in common that in the above basic configuration, four lens surfaces are aspherical.

In the lens according to the first aspect of the present invention, the lens has a diameter of 1° to 5°, counting from the object side. 7th. The eighth lens surface is an aspherical surface, and the conic constant Kl of these aspherical surfaces is 5. 7. 8 is (1-I)
−0.005<Kl<0.0
(1-II) 0.0<H5<0.
03(1-III) -0.03<H7<0
．． 0(1-IV) 0.0 < H8 <
The condition 7.0 is satisfied. Of course, the suffix to the conic constant indicates the order of the "lens surface with an aspherical surface" from the object side. For example, 5 above indicates this when the fifth lens surface from the object side is an aspherical surface. Represents the conic constant of an aspheric surface.

In the lens according to the second aspect of the invention, the angle is 1° counting from the object side and 5°. 7th. The tenth lens surface is an aspherical surface, and the conic constants of these aspherical surfaces are 5. 7. , O is (2-I
) −0.004<K, <0.0003(
2-II) 0.0 < H5 < 0.03 (
2(II) -0.04<H7<0.0(2-
IV) -0.035<K, O<0
．． The lens according to claim 3, which is characterized by the condition 01, is 3rd degree, 4th degree, and 4th degree, counting from the object side. Fifth. The eighth lens surface is an aspherical surface, and the conic constants K3, H4, H5, and H8 of these aspherical surfaces are (3-I)
-0.16<H3<-0.03(3-II
) −0.04<H4< −0.01(3-I
II) 0.01 < H5 < 0.03 (3
(V) The lens according to claim 4, which is characterized by the condition of 7.4 < Kg < 13.7, has an angle of 3 degrees and 4 degrees as counted from the object side. Fifth. The tenth lens surface is an aspherical surface, and the conic constants K3, 4, K5, and KIO of these aspherical surfaces are (4-I
) −0.05<H3< 0.1 (4-II
) −0.03<H4< −0.005(4-I
II) 0.004<H5<0.02(4-
IV) The lens according to claim 5, characterized by the condition that -0.07<K10<-0.01, has an angle of 1° and 6.0° as counted from the object side. 7th. The tenth lens surface is an aspherical surface, and the conic constant Kl of these aspherical surfaces is 6. 7. 10 is (5-I
) −0.03<K, <−0.01(5−
II) 0.001<H6<0.015(
5-III) -0.025<H7<-0.0
05 (5-IV) 0.002<K10<0
．． 015 is satisfied.

As is well known, for an aspheric surface, X is the direction of the optical axis, H is the height perpendicular to the optical axis, and C is the reciprocal of the radius of curvature on the optical axis.
When, curve X = [CH2/(1+ -1+K CH”)]+A2
・H2+A3・H""A4・H4...+A10・H
It is a curved surface obtained by rotating IO+ . . . around the optical axis, and the conic constant is K in the above formula.

[Function] The lenses according to claims 1 to 5 are all based on a tobogon type in order to achieve a wide angle of view. Although the Topobon type lens has a flat radial image surface with little curvature, the color breakage on the image surface increases as the angle of view becomes wider, reducing contrast.

In order to solve this problem of decreased contrast due to color cracking, the first group and the fourth group are made of a combination of positive and negative lenses. By doing this, it was possible to maintain the flatness of the radial image plane, which is an inherent advantage of the tobogon type, and to suppress color breakup on the image plane.

Additionally, in order to achieve a larger aperture, four lens surfaces are aspheric.

Generally, the larger the aperture, the more coma flare and the lower the contrast. In order to suppress coma flare, it is best to correct the extremely refracted surface among the input and exit surfaces.

However, with a spherical surface, the same correction cannot be made on any of the entrance and exit surfaces, so it is insufficient for correcting coma flare.

Therefore, an aspheric surface is used as a means to continuously change the refractive power from the axis toward the periphery.

This makes it possible to suppress coma flare at large apertures.

As in the lens of claim 1, the first. Fifth. 7゜When adopting an aspheric surface for the 8th lens surface, condition (1-I)
The aspherical shape of the first lens surface that satisfies the conditions is "an ellipsoidal surface that is rotationally symmetrical about the major axis," and the aspherical shape of the fifth lens surface that satisfies condition (1-II) is "an ellipsoidal surface that is rotationally symmetrical about the minor axis."",conditions(
The aspherical shape of the seventh lens surface that satisfies 1-III) is “
The aspherical shape of the eighth lens surface that satisfies the condition (1-IV) is "an ellipsoidal surface rotationally symmetrical about the major axis" and the condition (1-I), (III ), (1-
III), (1-m), the smallest coma flare can be achieved.

As in the lens of claim 2, the first. Fifth. 7th゜10th
When adopting an aspherical surface for the th lens surface, the condition (2-I
), the aspherical shape of the first lens surface is "an ellipsoidal surface that is rotationally symmetrical about the major axis or the minor axis," and the aspherical shape of the fifth lens surface, which satisfies the condition (2- The aspherical shape of the seventh lens surface that satisfies the condition (2-III>) is [an ellipsoid that is rotationally symmetrical about the long axis, 1, the condition (2-III)].
The aspherical shape of the tenth lens surface that satisfies m is an ellipsoidal surface J that is rotationally symmetrical about the major axis or the minor axis, and the condition (2-1),
The smallest coma flare can be achieved when (2-H), (2-III), and (2-IV) are satisfied.

Like the lens of claim 3, the third. 4th. Condition (3-I) when adopting an aspherical surface for the 5th and 8th lens surfaces
The aspherical shape of the third lens surface that satisfies the condition (3-II) is "an ellipsoidal surface that is rotationally symmetrical about the major axis," and the aspherical shape of the fourth lens surface that satisfies condition (3-II) is "an ellipsoidal surface that is rotationally symmetrical about the major axis."",conditions(
The aspherical shape of the fifth lens surface that satisfies 3-III) is “
The aspherical shape of the eighth lens surface that satisfies the condition (3-Eng. 3-II), (3
-III) and (3-IV), the smallest coma flare can be achieved.

Like the lens of claim 4, the third. 4th. 5th゜10th
When adopting an aspherical surface for the th lens surface, the condition (4-I
) The aspherical shape of the third lens surface that satisfies the condition ``r'' is an ellipsoidal surface that is rotationally symmetrical about the major axis or the minor axis, and the aspherical shape of the fourth lens surface that satisfies the condition (4-■ The aspherical shape of the fifth lens surface that satisfies condition (4-III) is ``rotationally symmetrical ellipsoidal surface'', condition (4-I).
The aspherical shape of the tenth lens surface that satisfies V) is "an ellipsoid that is rotationally symmetrical about the long axis", and conditions (4-I), (4-
II), (4-III), and (4-IV), the smallest coma flare can be achieved.

As in the lens of claim 5, the first. 6th. 7th゜10th
When adopting an aspherical surface for the th lens surface, the condition (5-I
) The aspherical shape of the first lens surface that satisfies condition (5-II) is "an ellipsoidal surface that is rotationally symmetrical about the major axis," and the aspherical shape of the sixth lens surface that satisfies condition (5-II) is "an ellipsoidal surface that is rotationally symmetrical about the minor axis." The aspherical shape of the seventh lens surface that satisfies condition (5-III) is "an ellipsoidal surface that is rotationally symmetrical about the major axis," and the aspherical shape of the tenth lens surface that satisfies condition (5-IV) is "It is an ellipsoidal surface rotationally symmetrical about the short axis", and conditions (5-I), (5II), (
5-III) and (5-IV), the smallest coma flare can be achieved.

[Examples] Below, three specific examples will be given for each lens in each claim.

That is, Examples 1 to 3 are examples of the lens according to claim 1,
Three embodiments of lenses according to claims 2 to 5 are successively described below.

In each example, the first lens is a positive meniscus lens, the second lens is a negative meniscus lens, the third lens is a negative meniscus lens, the fourth lens is a negative meniscus lens,
The fifth lens is a biconcave lens, and the sixth lens is a biconvex lens.

In each example, as shown in FIG. The distance between lens surfaces is d, (i=1 to 11), and the refractive index and Atsube number of the third lens are nj +ν, +(J・1 to 7), respectively.
).

Further, F indicates the combined focal length of the entire system, FNO indicates brightness, 2ω indicates the angle of view (degrees), and m indicates magnification.

The aspherical surface is marked with *, and the aspherical shape is specified by giving the conic constant and higher-order aspherical coefficient A41AGIA81A10 in addition to the axial radius of curvature.

In the display of the aspheric coefficient, E and the number following it indicate a power of 10. For example, E-12 means 10-12, and the number before E is multiplied by this power.

Example 1 F=43, FNO=3.0, 2 ω40
, m=0.11021rid, j
nj vB do 19.122 7.101
1 1.81600 46.62-C5,7ci4
2.243 2 1.84666 23.893
35.320 0.394 4 13.539 2.339 3 1.8
4666 23.895" 9.991 9.
9116 -8.825 1.924 4
1.84686 23.897" -11,38
30.506 8” -89,4862,32751,84686
23,899175,5985,67461,8160
046,6210-20.41127,396 11Co O,70071,5163364,
1512(X) Aspherical surface (first lens surface) K=-0.000515, A4=-7, 15130E-
8, A6= 1.16495E-9A8=-1,037
68E-12,A. =-6,80665E-14
Aspherical surface (fifth lens surface) K= 0.002189. A4=8.95439
E-7,A62-2,49698E-9As"-6,4
4227E-10. At. =-3,34125E-11
Aspherical surface (7th lens surface) K=-0.004243, A4" 2.43696E-
6, Aa= 4.77465E-9゜As” 1.13
520E 10. Ago" 1.48554E 12 Aspherical surface (8th lens surface) K= 0.204756. A4=-4,03111E
-8,A6=-1,13171E-9゜A,=-1,4
3566E-11, A□. = 1.44694E-13
Example 2 F=43, FNO”3.0.2ω:40
, m=o, 1102i ri at
j nj v3 de 18.612 6.4
50 1 1.72916 54.682 95.
466 2.868 2 1.78472 25.7
13 42.999 0.100 4 15.331 3.289 3 1.8466
6 23.895″ 10.477 9.82 6 -9.536 3.067 4 1.7407
7 27.797" -13,7670.100 8" -148,8721,00051,68893
31,08972,8145,92561,72916
54,6810-19,58126,891 11000.70071,5163364,1512C
0 Aspherical surface (first lens surface) K=-0.001882,A,=-1,32012E-
7, A6 2 1.33773E-9°As=-8,77
192E-12, A10”-1, 13864E 13 Aspherical surface (fifth lens surface) K・0.025465.A4=5.98326E-6
,A,=4.45995E-8°A8=-1,191
20E-10. A. =-5,55658E-11 Aspherical surface (7th lens surface) K” 0.025105.A4” 7.88462E-
6, A6” 3.19467E-8°A, = 2.67
490E-10. A10=-1,75191E-12 aspherical surface (8th lens surface) K=6.599211. A4=-4,42524E
-7,A62-1,5256'1E-8゜A8=-1,
05908E-10. A10=7.85857E-1
3 Example 3 F”43, FNO”3.0, 2ω”40
, m=o, 11021ri dlj
nj vJ do 19.274 7.073
1 1.81600 46.602 133.348
2.378 2 1.79571.25-363
37.941 0.100 4 15.508 2.694 3 1.8470
0 23.905" 10.651 9.689 6 -10.170 2.142 4 1.847
00 23.907" -13,9530.100 8" -93,7422,42651,788812
5,599100.3945,68361,82377
44,9010-20.15027,825 11co O,70071,5163364,1
512C0 Aspherical surface (first lens surface) K=-0.004646, A4=-2,96734E-
7, A6 = 1.99527E-9° A8 = -3,74
066E-12, Ayu. =-1,16922E-13 Aspherical surface (fifth lens surface) K2 0.022216. A4=4.74305E
-6, A6 = 6.57650E-8°As” 3.
92320E 10. Ago” 6.62444E-1
1 Aspherical surface (7th lens surface) K” 0.024389.A4” 6.55065E
6. A6"1.42533E-8゜As" 2.44
872E 10. Ago”-4,07196E42 Aspherical surface (8th lens surface) K= 1.376332. A4=-2,11774E
-7,A6=-1,11080E-8゜A8=-1,1
2122E-10. A engineer. = 8.50213E-13
The above are examples of the lens according to claim 1.

FIG. 2, FIG. 3, and FIG. 4 show aberration diagrams of Examples 1 to 3, respectively.

In addition to the aberration diagrams in Figs. 2 to 4, in the aberration diagrams of each example below, ■, ■, and ■ represent the d-line and C-line, respectively.
Indicates that it is related to the F line.

Further, the broken line in the diagram of spherical aberration indicates the sine condition, the solid line in the diagram of astigmatism indicates the radial condition, and the broken line indicates the tangential condition.

Example 4 F43, FNO=3.0, 2 (IJ=4
0, m=0.1102i rj
a, j nj v;1” 1
9.304 7. Yu87 1 1.81
600 46.622 107.469 2.68
7 2 1.84666 23.893 39.4
64 0.100 4 15.416 2.837 3 1.8466
6 23.895" 10.577 9.764 6 -10.145 2.441 4 1.846
66 23.897" -14,2520.100 8-125,6822,87151,84666i
23.899 156.796 6.062 6
1.81600 46.6210" -20.093
26,76711Co O,70071,5163
364,1512C0 Aspherical surface (first lens surface) K”-0.000012, A4= 1.00470E
7. A6” 1.88874E 9A8=-9,837
75E-12,A. =-7,07524E-14 Aspherical surface (fifth lens surface) K" 0.025851.A4 = 5.85952E
6. A6” 3.59628E 8As” 1.038
00E-10. Azo”-5,26022E 11 Aspherical surface (7th lens surface) K=-0.047149, A4= 9.10256E-
6, A [+= 2.80231E-8゜A82 1.0
2709E-9, A10=-1, 22280E-11 Aspherical surface (10th lens surface) K-0.009655, A4= 2.62192E-7
, A6=-1,06917E-8A82 6.5699
7E-11, A10=1.19467E-13 Example 5 F:43, m=0.1102 nj ν.

1.72916 54.68 1.78472 25.71 FN0=3.0 . 2ω=40 d, J 6.305 1 2.780 2 0.100 3.454 3 9.802 3.067 4 0, 100 1.287 5 5.999 6 26.823 1 ri de 18.647 2 97 .672 3 43.417 4 15.622 5" 10.624 6 -9.533 7' -13,820 8-148,165 972,135 10" -19,535 1,8466623,89 1,7407727,79 1,6889331,08 1,7291654,68 11(X) 0.700 7 1.5163
3 64.1512 ω Aspherical surface (first lens surface) K= 0.000278. A4=-5,33467E-
8, A6 = 1.79902E-9゜As” 1.03
923E-11, A+o"-1, 16110E-13 Aspherical surface (fifth lens surface) K = 0.025769.A, = 6.03683E-
6, A, = 3.40085E-8As”-3,386
65E4Q, A+ o”-5, 57060E41 aspherical surface (7th lens surface) K=-0.035253, A4= 9.11469E-
6, A, = 8.22897E-9°As” 9.24
953E 10. A+o”-7,86845E-12 Aspherical surface (10th lens surface) K” 0.005828. A,” 1.69207E-
7, A6”-8,03600E 9゜A8” 9.02
399E41. A10” 5.36599E-14 Example 6 F=43, FNo.2 3.0.2ω=40
9m=0.1102□rid,
j nj ν】1” 19.0957
．． 052 1 1.81600 46.602 1
14.099 2.164 2 1.83804 2
4.133 34.940 0.381 4 13.801 2.335 3 1.
84700 23.905' 10.037
9.9576 -8.835 1.892
4 1.84700 23.907″ -11,3
730.483 8-37,9062,25951,8345724,2
29135, 7435, 60561, 8176046,
2410"-20.46627,61611000
．． 70071,5163364,1512 aspherical surface (first lens surface) K=-0.000885,A, =-7,36048E
-8,A6=9.03124E-10A8=-1,2
1157E-12,A. =-6,08690E-1
4 aspherical surface (fifth lens surface) K= 0.002235. A4=9.99653E-
7, A6=-1,08762E-8As”4.3524
5E 10. A+o=2.81371E 11
Aspherical surface (7th lens surface) K=-0.003056, A4= 1.82052E-
6, A6=-8, 62348E-10As= 1.25
031E-10. Ato” 5.4b320E 13 Aspherical surface (10th lens surface) K” 0.002722. A4” 1.71505E
7. Aa” 1.04522E-9゜A8:1.293
45E-12, Ato'' 1.29020E-14 and above are examples of the lens of claim 2.

Aberration diagrams of Examples 4 to 6 are shown in FIGS. 5, 6, and 7, respectively.

Example 7 F:43, FNO"3.0, 2 ω"40i
ri a, Jl 19.1
58 7.332 12 97.603 2.70
3 23" 39.285 0.100 4" 16.047 2.621 5" 10.863 9.513 6 -9.256 2.153 7 -12.163 0.100 8" -118,7242,511 9132 ,7475,593 10-21,08727,344 11■ 0.700 12 Beautiful aspherical surface (third lens surface), m20, 1102 nj '1/j 1.81600 46.62 1.84666 23.89 3 1.84666 23.89 4 1.84666 23.89 5 1.84666 23.89 6 1.81600 46.62 7 1.51633 64.15=-0.155042, A4=-4,38106E-
7,A,=-4,10987E-10A8=1.64
907E-10. A.I. = 6.44532E-14 Aspherical surface (4th lens surface) K” 0.029660.A4” 2.11173E
6. A6” 6.44994E 9A8=-2,837
73E-10. Al o knee 2.75962E (2 aspherical surfaces (fifth lens surface) K= 0.018483.A4= 4.07403E-
6, A,, = 5.78273E-8As” 4.73
895E 10. A+. =-1,47753E-10 aspherical surface (8th lens surface) K=10.111426. A4=-1,40571E-
6, A6= 1.32190E-8A8=-2,102
82E-11, A 10 = 2.39161E-14 Example 8 F = 43, FN0 = 3.0.2ω40,
m=〇, 1102i rid,
j town ν, 1 18.509 6.49
9 1 1.72916 54.682 86.6
06 2.778 2 1.78472 25.71
3” 42.244 0.100 4” 15.743 3.151 3 1.84
666 23.895” 10.722 9.50
0 6 -8.927 2.706 4 1.7407
7 27.797 -12.136 0.100
8”-135,2321,00051,68893
31,08966,9855,44961,72916
54,6810-20.50727,593 1101) 0.700 7 1.51
633 64.1512 (X) Aspherical surface (third lens surface) K=-0.038989, A4=-8,94534E-
8, A6 = 4.01217E-9°A8 = 1.5
3664E-10. A10=9.71061E-1
4 aspherical surface (4th lens surface) K=-0.019988, A4=-1,65944E-
6, A6 = 7.98350E-9゜As” 8.62
200E 11. A10" 4.50556E 13 Aspherical surface (fifth lens surface) K= 0.013585.A4= 3.36281E-
6, A, = 4.06183E-8°As” 1-7
4365E 10. Ato2 1.33930E
10 Aspherical surface (8th lens surface) K”13.675701. A4”-1,35580E
-6, As” 1.07211E-8゜As” 1.9
9898E (1, Ato=4.72122E 14 Example 9 F43, FNO=3.0, 2 ω=40
, m=0.1102l r 4
d i j nj ν.

1 19.087 7.161 1 1
．． 81600 46.602 116.789
2.452 2 1.79300 25.463
" 38.498 0.1004'" 1
6.655 2.640 3 1.84700
23.905" 11.064 9.490
6 -9.677 2.000 4 1.
84700 23.907 -12.719 0
．． 1008"-90.0922,20951,7
870025, 65980.6225, 37061, 8
280044,0510-20.88128-016 11(1) 0.700 7 1.516
33 64.1512 (X) Aspherical surface (third lens surface) K knee 0.077084. A4=-2,24010E-
7, A6=-7,88924E40As” 1.699
16E (0.A+o=6.45342E 13 Aspherical surface (4th lens surface) K=-0.035713, A4=-2,37670E-
6, A6=5.14763E-9As=1.3950
5E 10. At. = 4.4.6582E-13 Aspherical surface (fifth lens surface) K = 0.022199. A4=4.40198E-
6, A, = 7.42344E-8°A, = 1.18
157E-9, A□. =-1,20128E-10 Aspherical surface (8th lens surface) K" 7.539045. A4" 1.47691E
6. A6” 1.61704E-8゜A8=-7,
85396E-12,A, 0=-3,89375E-
14 or more are embodiments of the lens according to claim 3.

Aberration diagrams of Examples 7 to 9 are shown in FIGS. 8, 9, and 10, respectively.

Example 10 F”43, FNO”3.0, 2ω40
, m-0.1102i ri ai
j nj v 31 19.460
6.756 1 1.81600 46.622
103.136 2.322 2 1.84666
23.893" 42.467 0.100 4" 17.709 3.384 3 1.84
666 23.895” 11.453 10.1
736 -9.367 2.351 4 1.84
666 23.897 -12.719 0.100 8 469.678 2.840 5 1.8466
6 23.899 102.999 5.459
6 1.81600 46.6210" -21,1
8327,10211COO,70071,51633
64,1512C0 Aspherical surface (third lens surface) K=-0.044760. A4=-1,58871E-
7, A6 = 1.17223E-9As = 1.1961
5E 10. Ago” 8.40437E-13 Aspherical surface (4th lens surface) K=-0.029267, A4=-1,893961,
-6, A6= 9.51764E-9As” 1.90
488E 10. At. =-4,59062E-12 aspherical surface (fifth lens surface) K= 0.017015. A4=3.91458E-
6, A6 = 119148E-8A8”4.76471
E 10. Ago”-1,01689E 10 aspherical surface (
10th lens surface) K=-0.069258, A4= 2.73847E-
6, A6=-1,12114E-8As” 8.814
65E-11, A10" 1.98004E 13 Example 11 F=43 -, FNo"3.0, 2ω40
, m=0.1102r; d+
J nj ν.

18.703 6.002 1 1.72916 5
4.682 92-166 2.445 2 1.
78472 25.713" 45.305
0.1004" 17.008 3.773
3 1.84666 23.895" 11
,198 9.9196 -9.053 2.
889 4 1.74077 27.797
-12.688 0.1008 -188.016
1.000 5 1.68893 31.08
9 60.835 5.666 6 1.
72916 54.6810" -20.61927
,32711Co O,70071,5163
364,1512CO Aspherical surface (third lens surface) K= 0.090778. A, = 1.53513E
-7, A6= 6.40989E-9°As” 1,
43636E 10. A+o=-6,91347E 1
3 Aspherical surface (4th lens surface) K=-0.017240. A4 knee 1.47318E-
6, A6 = 1.36982E-8゜As” 4.0
8383E-11, Ago"-1, 89787E 12
Aspherical surface (fifth lens surface) K= CLO12544, A4= 3.38764E-
6, A6=-1,78870E-9゜A8=-3,18
456E-10. A. =-9,67800E-11
Aspherical surface (10th lens surface) = -0.063618, A4 = 2.70054E~
6. A, = -1,01562E-8゜As” 8.2
4547E-11, A10"-1, 77132E-13
Example 12 F=43, Fso"3.0.2ω=40
, m=o, 11021 r; d;
J n = ν.

1 19.173 7.099 1 1.8160
0 46.602 108.226 2.271
2 1.82200 24.573″ 36.093
0.155 4” 14.898 2.415 3 1.84
700 23.905” 10.627 9.54
0 6 -9.002 1.902 4 1.8470
0 23.907 -11.688 0.270 8 -95.306 2.203 5 1.825
00 24.499 111.617 5.500
6 1.82100 45.5210" -20.
78428,41311Co O,70071,5
163364, 1512 aspherical surface (third lens surface) K=-0.002693, A4=-2,61409E-
8, A6 = 3.19895E-9°A8 = 9.91
433E-11, A10 = 7.90081E-13 Aspherical surface (4th lens surface) K = -0.007107, A4 = -6,56645E-
7,A6=9.05567E-1OA,=-9,48
764E-11, A□. =-3,80403E-13 Aspherical surface (fifth lens surface) K= 0.004912. A4 = 1.64748E-
6, A6 = 9.05621E-9°A8 = -1,04
969E-9, A10=-9, 55586E-11 aspherical surface (10th lens surface) K=-0.019230. A4=8.99120E-
7, A6=-3,39620E-9°As” 1.94
323E-12, Ago''-1, 73690E 14 and above are examples of the lens of claim 4.

Examples 10 to 10 are shown in FIG. 11, FIG. 12, and FIG. 13, respectively.
12 is shown.

Example 13 -43 , m-o, 1102 nj　　　　ν.

1.81600 46.62 1.84666 23.89 FNO"3.0.2ω; 40 d, J 7.240 1 2.640 2 0, 100 2.540 3 10.620 1 ri de 19.533 2 123 .825 3 40.047 4 13.732 5 9.718 1.84666 23.89 6” -10.6492,70041,84666
23,897" -15,1450.100 8-104,0592,15051,8466623,
899206, 1455, 53061, 8160046
,6210"-19,48626,78011
0.700 7 1.51633 64.15
12 C0 Aspherical surface (first lens surface) K=-0.018916,A,=-8,93576E-
7, A6= 3.24972E-10A8=-1,21
662E-11,A. =-8,51112E-1
5 Aspherical surface (6th lens surface) K= 0.009341. A4=4.18672E-5
,A6=1.54102E-8As knee 3.0946
8E 9, Ago” 5.09647E 1
1 Aspherical surface (7th lens surface) K=-0.018353, A4=5.60739E-
6, A, = -2,27724E-8A8 = 7.644
63E-10. A10=-4,51643E-12 Aspherical surface (10th lens surface) K"0.014373.A4" 5.30585E
7. A6” 3.71810E 9A8=6.748
98E-11, A1o=1.01278E-13 Example 14 F"43, FNO"3.0, 2ω:40
, m=0.1102i r□
d, j nJ v31”
18.5'? 6 6.450 1 1.72
916 54.682 110.612 2.6
40 2 1,78472 25.713
40.793 0.100 4 13.392 2.890 3 1.
84666 23.895 9.667 10.
490 6' -9,3622,83041,74077
27,797" -13,0530.100 8-105,9801,00051,6889331,
08978, 2506, 04061, 7291654,
6810"-19,40626,59011(X)
0.700 7 1.51633 6
4.1512 C0 Aspherical surface (first lens surface) K=-0.010392, A4=-5,74601E-
7,A6=4.23767E-10A8=-6,74
072E-12,A. =-4,10049E-1
4 Aspherical surface (6th lens surface) K" 0.001434. A4" 9.86466E
-6, As” 6.27114E-9゜As” 2.1
5429E-9, Ato" 3.48288E-11 Aspherical surface (7th lens surface) K=-0.005094, A4= 3.71498E-
6, As”-1,79749E-8゜As” 4.68
985E-10. A1o= 1.52444E 13 Aspherical surface (10th lens surface) K= 0.002723. A4=-2,81182E-
7, A6 = 7.38776E-10A8 = 4.84
538E-11, AI. = 9.21569E-15 Example 15 F=43, FN0=3.0. 2ω4
0, m=o, 11021 ri
d, j nj 1) J do 19.
659 6.970 1 1.81600 46.6
02 169.209 2.260 2 1.79
832 25.283 40.196 0.100 4 14.017 2.620 3 1.8470
0 23.905 9.774 10.650 6' -11,5372,58041,847002
3,907' -16,6700.100 8-85,0721,62051,7657226,4
0999,9055,57061,8241544,8
210" -19,46227,65011■ 0
．． 700 7 1.51633 64.1512
Aspherical surface (7th lens) K=-0.025827, A4=-1,10827E-
6, A6=-4,35123E-10A8=-1,09
772E-11,A. =-1,10429E-14
Aspherical surface (sixth lens surface) K= 0.011720. A4 = 1.09772E-
5, A6” 2.37883E 8As” 2.431
71E-9, A+o” 4.70926E 11 Aspherical surface (7th lens surface) K=-0.023183, A4= 5.41541E-
6, A6=-2,53901E-8°A8=6.09
523E-10. A10=-5,58826E-12 Aspherical surface (10th lens surface) K" 0.008552. A, "-3,32570
E-7, A6”-3, 73085E-9°A8=7.
91735E-11, A10= 1.99796E-1
3 or more are embodiments of the lens according to claim 5.

Examples 13 to 14 are shown in FIG. 14, FIG. 15, and FIG. 16, respectively.
15 is shown.

Aberrations are well corrected in each example.

[Effects of the Invention] As described above, according to the present invention, a novel reading lens for a scanner can be provided.

Since this lens is constructed as described above, the half angle of view is 2
It has a wide field of view of 0 degrees, has sufficiently high contrast even at high spatial frequencies of 71.4 lines/mrn, is bright at FNo. 3, and has a sufficiently high aperture efficiency. .

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining the structure of the lens of the present invention, and FIGS. 2 to 16 are aberration diagrams for each example. 10., first lens, 12. , , second lens, 1
4. ,, third lens, 15. , ,Aperture, 16. ,
, fourth lens, 18. , , fifth lens, 20. ,
, sixth lens, 22. , , 7th lens height (Figure z /17.νγ 2 Figure (Example A) F/No, 5 Y=752.4 Y=(52,4 Spherical aberration Astigmatism Royal aberration (y:) Diagram showing coma aberration (actual sales example 2) F/fJ. Y=152.4 Y=4524 Coma aberration 46- Part 4 figure (Toloba b) Pressure/N. Y=152.4 Y=452.J Spherical surface 8 rose, hydrofluoric acid difference distortion mortar difference (z) Near aberration ring 6 figure (buzz b mohiikuri) F/N. Y=452.4 Y= 752.4 -0.2000.20 ()20 0 020 Spherical aberration Astigmatism Distortion (phantom coma side θ Figure (Omitsu Iku 18) Seven orgasms 9) F/NO UY=Iri24 Y=152.4 -0.200020-0200020-0200020
Spherical aberration Astigmatism 2 Distortion aberration (ㅅ) Comatic aberration ladder ((Fig. (1) Y=4524 zu ≧ Shoyo Tamata M ('/-) Comatic aberration ladder (U) F/N. 'f'=+52..d Y=152.J (4 (Example 1)) F/No. 1-4) F/No, b 'I' = 152.4 Y = 152.4 side (6 (Torayasu Example 15) F/hJo r = 152.4 Y = +52.A Spherical aberration Astigmatism M Also, 3 glances #(,y,> core aberration

Claims (1)

[Claims] 1. A document reading lens used at a reduction magnification, in which first to fifth groups are arranged sequentially from the object side to the image side, and the second group and the third group are arranged sequentially from the object side to the image side. A diaphragm is arranged between them, and the first group is composed of a first lens that is a positive lens and a second lens that is a negative lens that is cemented to the image side of this first lens. is a third lens that is a meniscus lens with a convex surface facing the object side, the third group is a fourth lens that is a meniscus lens with a convex surface facing the image side, and the fourth group is a negative lens The fifth lens is composed of a fifth lens and a sixth lens which is a positive lens cemented to the image side of the fifth lens. The 1st, 5th, 7th, and 8th lens surfaces are aspherical, and the conic constant of these aspherical surfaces is K_1.
, K_5, K_7, K_8 are (1-I)-0.00
5<K_1<0.0 (1-II) 0.0<K_5<0.03 (1-III) -0.03<K_7<0.0 (1-IV) 0.0<K_8<7.0 A reading lens for a scanner having a configuration of 7 elements in 5 groups, which satisfies Condition 1. 2. A document reading lens used at reduced magnification, in which the first to fifth groups are arranged sequentially from the object side to the image side, and an aperture is arranged between the second and third groups. The first group includes a first lens that is a positive lens and a second lens that is a negative lens that is cemented to the image side of the first lens, and the second group has a convex surface on the object side. The third lens is a meniscus lens with a convex surface facing the image side, and the fourth lens is a meniscus lens with a convex surface facing the image side. A sixth lens is a positive lens cemented to the image side of the fifth lens, and the fifth lens is a seventh lens that is a parallel plane glass. 7. The tenth lens surface is an aspherical surface, and the conic constant K_1 of these aspherical surfaces is
, K_5, K_7, K_1_0 are (2- I )-0.
004<K_1<0.0003(2-II)0.0<K_
5<0.03 (2-III)-0.04<K_7<0.0 (2-IV)-0.035<K_1_0<0.01, 7 elements in 5 groups Reading lens for the configured scanner. 3. A document reading lens used at reduced magnification, in which the first to fifth groups are arranged sequentially from the object side to the image side, and an aperture is arranged between the second and third groups. The first group includes a first lens that is a positive lens and a second lens that is a negative lens that is cemented to the image side of the first lens, and the second group has a convex surface on the object side. The third lens is a meniscus lens with a convex surface facing the image side, and the fourth lens is a meniscus lens with a convex surface facing the image side. and a sixth lens which is a positive lens cemented to the image side of the fifth lens, and the fifth lens group is a seventh lens which is a parallel plane glass, and the fifth lens group includes the third, fourth, and sixth lenses counting from the object side. 5. The eighth lens surface is an aspherical surface, and the conic constant K_3 of these aspherical surfaces is
K_4, K_5, K_8 are (3-I)-0.16<
K_3<-0.03(3-II)-0.04<K_4<-
0.01 (3-III) 0.01<K_5<0.03 (3-IV) 7.4<K_8<13.7 For scanners with 7 elements in 5 groups, characterized by satisfying the following conditions. reading lens. 4. A document reading lens used at reduced magnification, in which the first to fifth groups are arranged sequentially from the object side to the image side, and an aperture is arranged between the second and third groups. The first group includes a first lens that is a positive lens and a second lens that is a negative lens that is cemented to the image side of the first lens, and the second group has a convex surface on the object side. The third lens is a meniscus lens with a convex surface facing the image side, and the fourth lens is a meniscus lens with a convex surface facing the image side. and a sixth lens which is a positive lens cemented to the image side of the fifth lens, and the fifth lens group is a seventh lens which is a parallel plane glass, and the fifth lens group includes the third, fourth, and sixth lenses counting from the object side. 5. The tenth lens surface is an aspherical surface, and the conic constant K_3 of these aspherical surfaces is
, K_4, K_5, K_1_0 are (4- I )-0.
05<K_3<0.1 (4-II) -0.03<K_4<-0.005 (4-I
II) A reading lens for a scanner having a configuration of 7 elements in 5 groups, which satisfies the following condition: 0.004<K_5<0.02 (4-IV)-0.07<K_1_0<-0.01. 5. A document reading lens used at reduced magnification, in which the first to fifth groups are arranged sequentially from the object side to the image side, and an aperture is arranged between the second and third groups. The first group includes a first lens that is a positive lens and a second lens that is a negative lens that is cemented to the image side of the first lens, and the second group has a convex surface on the object side. The third lens is a meniscus lens with a convex surface facing the image side, and the fourth lens is a meniscus lens with a convex surface facing the image side. and a sixth lens which is a positive lens cemented to the image side of the fifth lens, and the fifth lens is a seventh lens which is a parallel plane glass. 7. The tenth lens surface is an aspherical surface, and the conic constant K_1 of these aspherical surfaces is
, K_6, K_7, K_1_0 are (5-I)-0.
03<K_1<-0.01 (5-II) 0.001<K_
6<0.015(5-III)-0.025<K_7<-
0.005 (5-IV) 0.002<K_1_0<0.0
A reading lens for a scanner consisting of 7 elements in 5 groups, which satisfies the following conditions: