JPH03257411A - Read lens for scanner - Google Patents

Abstract

PURPOSE:To realize a bright, wide-field-angle read lens for the scanner which is based upon a topogon lens by employing five-group, seven-element constitution which includes aspherical surfaces as the 1st, 3rd, 6th, and 8th lens surface from the object side and also has cone constants satisfying specific conditions. CONSTITUTION:A 1st group is the cemented lens consisting of a 1st positive lens 10 and a 2nd negative lens 12, and a 2nd group is a 3rd meniscus lens 14 which is convex to the object side; and a 3rd group is a 4th meniscus lens 16 which is convex to the image side and a stop is arranged between the 2nd and 3rd groups. A 4th group which is the cemented lens of a 5th negative lens 18 and a 6th positive lens 20 is arranged further behind it and a 7th lens 22 which is parallel plane glass is provided as a 5th group. The 1st, 3rd, 6th, and 8th lens surfaces of those lenses are aspherical surfaces and the cone constants K1, K3, K6, and K8 of the aspherical surfaces are set satisfying conditional inequalities I - IV.

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 μm, the reading lens for the scanner needs a resolution of 71.4 lines/mm on the light-receiving surface of the CCD, and in addition, the above-mentioned space is High contrast with respect to frequency is required.

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

From this point of view, a topobon type scanner reading lens has been proposed (for example, Japanese Patent Laid-Open Nos. 6375721 and 64-23215).

[Problems to be Solved by the Invention] However, on the other hand, the Topobon 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
Based on a Topobon type lens, it is bright at F6° = 3,
The objective is to provide a new reading lens for scanners with 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 angle of the lens is 1° counting from the object side. 6th. The 8th lens surface is an aspherical surface, and the conic constants of these aspherical surfaces are 8 for 1lK31, 6j, and 0 (1-I) −0.02<K,
< 0.0(1-II) 0.42
< H3 < 0.54 (1-III)
0.0 < KG < 0.03 (1-IV)
−0.18<Ka<2.0
satisfies the following conditions. Of course, the suffix to the conic constant "indicates the order of the aspherical lens surface J from the object side. For example, 6 above indicates this when the sixth lens surface from the object side is aspherical. Represents the conic constant of an aspheric surface.

In the lens according to the second aspect of the present invention, the angle of the lens is 1°, 3rd, and 30° as counted from the object side. 6th. The tenth lens surface is an aspherical surface, and the conic constants of these aspherical surfaces are □+, 3LK61, 1o, (2-I
) −0.015<K□〈0.0(2-II)
0.04 < H3 < 0.8 (2-III)
0.0 < H6 < 0.03
(2-IV) -0.005<. <
The lens according to claim 3, which is characterized by the condition of 0.01, has an angle of 1° and 3.0° as counted from the object side. 8th. The 10th lens surface is an aspherical surface, and the conic constants of these aspherical surfaces are 3+KatK+a, 1 (3-factor) -0.015<K1<-0.0
05(3II) 0.25 <H3<
0.65 (3-III) 4.0 <
B < 14.0 (3-IV) -0.02
5<K1. The lens according to claim 4, which is characterized by the condition of <-0.015, has an angle of 1° and a 4th angle as counted from the object side. Fifth. The sixth lens surface is an aspherical surface, and the conic constants Kl+ of these aspherical surfaces are 4+ and 5. 6 is (4-I)
-0.002<K, <0.005 (4-Work I) -0.02<K4<-0
．． 005(4-III) 0.005 < L <
0.010(4-■\') 0.005
The lens according to claim 5, which is characterized by the condition of < K 6 < 0.02, has an angle of 1° and a 4th angle as counted from the object side. Fifth. The seventh lens surface is an aspherical surface, and the conic constant Kl of these aspherical surfaces is 4. Kg, 7, (5-I)
-0.002<K,<
0.005 (5-II) 0.02 <
K4 < -0.005 (5-III)
0.005<K, <0.015(
5-m −0.025<K,<
-0.012.

In this way, the lenses according to claims 1 to 5 have in common that the first lens surface is an aspherical surface.

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 , the curve x・[CH3I(1+f+K)C”H”)]+A2
・H2+A3・H3+A4・H4...+A□.・H
It is a curved surface obtained by rotating 1°+... around the optical axis, and the conic constant is K in the above formula.

[Function] The lenses of claims 1 to 5 are all based on the topobon type in order to achieve a wide angle of view. Although the tobogon lens has a flat radial image surface with little curvature, the color breakage on the image surface increases as the angle of view increases, 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 Topobon 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 eight incident surfaces, so this 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. Third. 6th degree: 1 condition when using an aspherical surface for the 8th lens surface (1-I)
The aspherical shape of the first lens surface that satisfies is "an ellipsoidal surface that is rotationally symmetrical about the major axis," and the aspherical shape of the third lens surface that satisfies condition (1-II) is "an ellipsoidal surface that is rotationally symmetrical about the minor axis. The aspherical shape of the sixth lens surface that satisfies the conditions (1-III) for surface J is "ellipsoidal surface rotationally symmetrical about the short axis", and the condition (
The aspherical shape of the eighth lens surface that satisfies the condition (1-IV) is "an ellipsoid that is rotationally symmetrical about the major axis or the minor axis", and the condition (1-IV) is satisfied.
I), (1-II), (1-III), (1
-IV), the smallest coma flare can be achieved.

As in the lens of claim 2, the first. Third. 6th degree 1st O
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], and the aspherical shape of the third lens surface that satisfies condition (2-II) is [an ellipsoidal surface that is rotationally symmetrical about the minor axis]. The aspherical shape of the sixth lens surface that satisfies condition (2-III) is "an ellipsoidal surface rotationally symmetrical about the short axis," and the aspherical shape of the tenth lens surface that satisfies condition (2-IV) is "It is an ellipsoid surface that is rotationally symmetrical about the major axis or minor axis," and conditions (2-I), (2
-II), (2-III), and (2-IV), the smallest coma flare can be achieved.

As in the lens of claim 3, the first. Third. 8th゜10th
When adopting an aspherical surface for the th lens surface, the condition (3-I
) The aspherical shape of the first lens surface that satisfies the condition 5 is "an ellipsoidal surface that is rotationally symmetrical about the major axis," and the aspherical shape of the third lens surface that satisfies the condition (34I) is "an ellipsoidal surface that is rotationally symmetrical about the minor axis." ”, the aspherical shape of the eighth lens surface that satisfies condition (3-III) is “an ellipsoidal surface rotationally symmetrical about the short axis”, condition (3-I
The aspherical shape of the tenth lens surface that satisfies V) is "an ellipsoidal surface that is rotationally symmetrical about the major axis," and conditions (3-I), (3
II), (3-III), and (3-IV), the smallest coma flare can be achieved.

As in the lens of claim 4, the first. 4th. 5゜When adopting an aspherical surface for the 6th lens surface, condition (4-I)
The aspherical shape of the first lens surface that satisfies 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 condition (4-II) is "rotationally symmetrical about the major axis. The aspherical shape of the fifth lens surface that satisfies condition (4-III) is "an ellipsoid that is rotationally symmetrical about the short axis" and condition (4-IV).
The aspherical shape of the sixth lens surface that satisfies [
The smallest coma flare can be achieved when satisfying I), (4-III), and (4-IV).

As in the lens of claim 5, the first. 4th. 5゜6 When adopting an aspheric surface for the seventh lens surface, the condition (5
The aspheric shape of the first lens surface that satisfies condition (I) is "an ellipsoid that is rotationally symmetrical about the major axis or minor axis," and the aspheric shape of the fourth lens surface that satisfies condition (5-II) is "major axis The aspherical shape of the fifth lens surface that satisfies condition (5-III) is "an ellipsoidal surface rotationally symmetrical about the short axis", condition (5-III).
The aspherical shape of the seventh lens surface that satisfies -IV) is an ellipsoidal surface that is rotationally symmetrical about the r long axis, and conditions (5-4), (
The smallest coma flare can be achieved when satisfying 5-II), (5-Ill), and (5-IV).

[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. Let the distance between the lens surfaces of
7).

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

Aspherical surfaces are marked with *, and in addition to the axial radius of curvature, the conic constant and the higher-order aspherical coefficient A4. A6! AIIIA1, K3, K
6. Specify the aspherical shape by giving K10.

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

Example I F=43, FNO"3.0.2c, +=40
, m=0.11021 rt d+
j rJl” 19.878 7.33
7 1 1.81600 46.628 2 131.202 3.016 2 1
．． 84666 23.893” 42.0B4
0.1004 14.706 2.749
3 1.84668 23.895 10
．． 175 9.8376" -10.5622,
60441,8466623,897-15,0890
．． 100 8" -115,6572,53151,84666
23,899176,5025,8246i,8160
0 46.6210 -19.636 25.81
811 0) 0.700 7
1.51633 64.1512o.

Aspherical surface (first lens surface) K”-0.012875,A,”-6,14904E-
7, As” 2.24452E-9Aa”-8,310
97E-13, At. =-1,90724E-13 Aspherical surface (third lens surface) K” 0.486862.A4= 1.42816E-
6, As”-9,53223E-9Aa”-2,407
42E-10. Alo” 6.676 6E-13 Aspherical surface (6th lens surface) K= 0.027087.A4=-1,61834E-
5,A,=-5,16782E-8゜As” 2.34
510E-9, Ato” 3.93914E-119 Aspherical surface (8th lens surface) K=0.158652.A4=-2,28958E-8
,As”-1,26378E-8As”-1,4035
0E-10. Alo" 8.37215E-13 Example 2 F"43, FNO"3.0.2ω; 40
, m=0.1102i rid, j
njl” 18.747 6.621 1 1
．． 72916 54.682 103.694 2.
885 2 1.78472 25.713”
42.015 0.100 4 13.984 2.923 3 1.8466
6 23.895 9.924 9.875 6J-9,4062,86341,7407727,7
97-13,1800.100 8”-112,8011,05751,68893
31,0897'5.969 5.878 6 1.
72916 54.6810 -19.466 26.
154 11 ω 0.700 7 1.51633
64.1512 ω Aspherical surface (first lens surface) K=-0.007169,A,=-4,74529E-
7, A6 = 3.49933E-9゜0 Aa”-4,03277E-13, Ato”-2,75
597E-13 Aspherical surface (third lens surface) K= 0.479994. A4= 1.20105E-
6, A6=-9,12954E-9゜Aa=-1,59
722E-10. Alo"-6,79514E-16 aspherical surface (sixth lens surface) K= 0.007906.A4"-1,16600E-
5, A, = 1.33105E-8゜Aa”4.686
66E 9, Ago" 1.30569E-11 Aspherical surface (8th lens surface) = 1.833595.A, = -2,63996E-
7, A6=-8,42267E-9°A8=-8,30
107E-11, A10=5.57806E-13 Example 3 F”43, FNO”3.0.2ω=40
, m=0.11021rid, j
njl” 19.891 7.051 1 1
．． 81600 46.602 486.975 2.5
54 2 1.78870 25.593" 4
0.923 0.100 4 15.235 2.814 3 1.8470
0 23.90:) 10.416 9.879 6” -10.8292, 30541, 847002
3,907-15,3050.100 8 Stomach -88,7682,25751,7769'?
25.999 99.419 5.562
6 1.82462 44.7210 -19
．． 650 28.72511 ω 0.7
00 7 1.51633 64.1512
ω Aspherical surface (first lens surface) K"-0.016887, A4"-7,65519E
7. As” 2.07059E-9゜Aa” 7.54
113E-13, Ato”-2, 38592E-13 Aspherical surface (third lens surface) = 0.481292.A, = 1.49324E-
6,AI,=-8,37507E-9゜Aa"-2,4
8800E-10. Alo” 3.92444E-13
Aspherical surface (sixth lens surface) K=0.023708. A4"-1, 36558E-5
,A6"-4,09503E-8゜Aa"4.8118
9E-9, Alo" 3.60142E-11 aspherical surface (
8th lens surface) K, 0.601475. A4=-9,92378E-
8, A6=-1,22957E-8゜A11"-1,4
7791E-10. A1, K3, K6, K10" 8.
65394E-13 and above are examples of the lens of claim 1.

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

1 2 In addition to the aberration diagrams shown in Figures 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 m and F lines.

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.

3 Example 4 F"43, FNo."3.0. 2 (11”
40i ri di j
l” 19.780 7.390 12
125.799 2.897 23”
40.760 0.1004 14.590
2.6895 10.201119.692
6″' -10.4012,5057-14,62
60.100 8-110.8662,712 9171,0425,906 10" -19,82726,93311(-)
0.700 12 oO Aspherical surface (first lens surface) K knee 0.008700. A4”-4,73540E-
7, A6” 2.94613E-9A11=-2,53
852E-12, A10=-2, 08357E-13 Aspherical surface (third lens surface) K” 0.485464.A4”, 1.46751E
-6, A6”-1,37360E-84 51,8466623,89, m=0.1102 j 1.81600 46.62 1.84666 23.89 3 1.84666 23.89 4 1.84666 23.89 6 1.81600 46.62 7 1.51633 64.15 As=-2,35644E-10.Ax.=5.19
578E-13 Aspherical surface (6th lens surface) K= 0.023336. A4=-1,48277E-
5, A6”-1,29518E-7As”-4,469
77E-9, Ago” 6.60042E-11 Aspherical surface (10th lens surface) K” 0.006464. A4” 1.96849E-
7, A6”-7,89873E-9Aa” 5.793
41E 11. A+. = 8.62813E-14 Example 5 F=43. FNo=3.0.2ω=402m=0.11
02iri dt J n*'
Jl” 19.230 6.597 1 1.
72916 54.682 120.904 3.1
53 2 1.78472 25.713" 4
6.380 0.100 4 14.894 3.338 3 1.8466
6 23.895 10.237 9.691 6” -9,9443,22741,740772
7,797-14,5580.100 8-127,7141,03351,6889331,
08972,9736,11961,7291654,
6810″' -19,12726,66411oo
O, 70071, 5163364, 1512c
x> Aspherical surface (first lens surface) K=-0.008819,A,=-4,59457E-
7, A, = 3.04166E-9°A, = -5,53
915E-12,A. , -3,08770E-13 Aspherical surface (third lens surface) K = 0.761059. A4 = 1.76115E-
6, A6=-1,70993E-8Aa"-2,656
17E-10. Ago" 8.65774E-13 Aspherical surface (6th lens surface) K = 0.021628.A, = -1,89236E-
5, A6=-1,37136E-7A,"-5,858
75E-9, Ago” 6.09469E-11 Aspherical surface (10th lens surface) K= 0.004125.A4= 2.73481E-
7,A,=-7,91019E-9°As=8.238
84E-11, Ago” 8.21035E-14 Example 6 F:43, FNO”3.0.2ω”40
, m”0.1102i rt d,
j nj′yj1” 19.076 7.0
66 1 1.81800 46.602 118
．． 029 2.186 2 1.84083 24.
063o 34.879 0.370 5 6 4 13.331 2.324 3 1
．． 84700 23.905 9.881 1
0.2046 pull -8,9111,91341,8
470023,907-11,4650.429 8-85,2692,26251,8335224,2
59136, 4595, 60361, 8184346,
0510” -20.39627,2651100
0.70071,5163364,1512o.

Aspherical surface (first lens surface) K=-0.001498, A4=-1,19129E-
7, A6= 9.42343E-10Aa” 4.15
178E-13, Axo”-4, 66702E-14 Aspherical surface (third lens surface) K” 0.052943. A4=2.02908E-
7, As=-2,08676E-9Aa''-2,045
93E-11, Ato” 2.39943E-15 Aspherical surface (6th lens surface) = 0.002075.A4”-3,64219E-
6, A6 = 2.46504E-9Aa”-4,930
49E-10. Ato”-4,49597E-12 Aspherical surface (10th lens surface) K”-0.003940. AI” 1.85301E-
7,As”-7,48914E 107 A,=3.07107E-12,A,.=2.16
6130-14 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”3.0.2ω”40i
r+ dt j1″19.413 7
．． 305 1 2 111.196 2.593 23” 3
7.658 0.100 4 14.041 2.397 5 10.127 9.977 6 -9.232 2.073 7 -12.146 0.125 8" -98,0012,393 9172,4795,660 10 ″-20.41427,39 Ei 11 (X) 0.700 12 ω Aspherical surface (first lens surface) 5 1.84666 23.89 6 1.81600 46.62, m=o, 1102 j 1.81600 46 .62 1.84666 23.89 7 1.51633 64.15 4 1.84666 23.89 3 1.84666 23.89 8 K"-0.005937, A4"-4, 21992E-
7, As” 3.30789E-9As” 1.267
69E-13, AI. Knee 1,86660E-13 Aspherical surface (third lens surface) K” 0.261718.A4= 8.78116E-
7, As”-6,28972E-9Aa”=1.138
41E-10. Azo”-4,34093E-13 Aspherical surface (8th lens surface) K=4.381125.A,=-8,28745E-
7, A6. -5.57902E-10A4=-9,90
593E-12, Ato" 5.20825E-13 Aspherical surface (10th lens surface) K=-0.016080.A, = 1.01011E-
6, A6=-6,58204E-9A,=-9,584
29E-13, AI (1=1.547702-13 Example 8 F=43, Fxo=3.0.2ω"40
, m”o, 1102iri dt jnj
νjl″ 18.946 6.658 1
1.72916'54.682, 106.785
3.036 2 1.78472 25.713”
43.246 0.100 4 14.556 3.028 3 1.8466
6 23.895 10.210 9.864 6 -9.116 2.808 4 1.7407
7 27.797 -12.641 0.100
8ゞ -139,2681,00051,688933
1,08966,2645,76461,729165
4,6810" -20.08026,97911ψ
0.700, 7 1.51633 64
．． 1512 ω Aspherical surface (first lens surface) = -0.009094,A, = -5,86372E-
7, A6 = 4.35980E-9A, = -2,477
28E-12, AI. =-3,46366E-13 Aspherical surface (third lens surface) K” 0.628584.A4” 1.53398E-
6, A6”-1,34100E-8°A, =-2,25
218E-10. A. = 1.35986E-13 aspherical surface (8th lens surface) K=13.721388. A4=-1,42464E-
6, A6=-9, 47119E-10Ag=-1.08
'267E-11, At. = 6.23584E-13
Aspherical surface (10th lens surface) "-0.020933, A4" 1.49532E
6. As"-1,14613E-8゜Aa" 9.29
431E42. Ato” 3.20126E-13 Example 9 F=43, FNO=3.0.2ω”40,
m=0.11029 0 j ri dl j nJ
'vjl o 19.683 7.231
1 1.81600 46.602 14
7.666 2.594 2 1.80507
25.073” 39.131 0.100
4 15.010 2.578 3 1
．． 84700 23.905 10.458
9.7976 -9.807 2.056
4 1.8100 23.907 -13.1
78 0.1008" -95,9822,30
251,7936525,43986,1255,51
561,8262744,3910" -20.47
327,77511φ 0.700 7
1.51633 64.1512 ω Aspherical surface (first lens surface) K=-0.012538,A,"-6,59604E-
7, As” 3.25726E-9°AB=-6,93
862E-13, Ato"-2, 67687E-13 Aspherical surface (third lens surface) K = 0.471259.A, = 1.50235E-
6,A,=-1,05458E-8Aa''-2,375
25E-10. Ato"-2, 12367E43 Aspherical surface (8th lens surface) 1 K" 7.160813. A4=-1,33650E-
6,AG"-4,50872E-10A8=1.02
422E-11, A10 = 9.65057E-13 Aspherical surface (10th lens surface) K”-0.023884, A4” 1.46540E-
6, As=-1,08527E-8°As=5.316
01E-12, A1o=3.23515E-13 or more is an example 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. 2ω24
0, m=0.1102i ri
dl j nil” 19.493 7
,176 1 1.81600 413.622
110.521 2.602 2 1.84666
23.893 39.805 0.100 4” 15.820 2,857 3 1.84
666 23.895" 10.903 9.10
9 6″ -9,7392,20141,8466623
,897-13,2550.100 8-109,1992,84851,846B6 23
．． 899 175.921 5.929 6 1.
8160046.622 10 -20.387 27.54411
CoO,70071,5163364,1
512o.

Aspherical surface (first lens surface) "0.004309.A4" 1.00678E-
8, A6 = 3.70297E-9Aa = -5,147
92E-12, A+o=-1, 56807E-13 Aspherical surface (4th lens surface) K”-0.016949, A4=-1, 25673E-
6, As”-2,37674E-9Aa” 7.391
23E-12, A□o” 2.77289E-12 Aspherical surface (fifth lens surface) K= 0.010097.A4= 2.57874E-
6, A6=1.58897E-8As”-2,2192
3E-10. At. =-7,13169E-11 Aspherical surface (sixth lens surface) K= 0.015227. Eight, =-1,05550E-
5, A6=-5,19138E-8Aa" 2.992
90E-9, Alo”-3, 44689E-12 Example 11 F”43, FNO”3.0.2ω”40
, m"0.11'02i ri di
j na ν.

1” 18.632 6.459 1 1.72
91B 54.682 92.804 2.713
2 1.78472 25.713 3 41.040 0.1004' 1
4.880 3.039 3 1.84666
23.89511 10.484 9.2656
' -9,0812,67641,7407727
,797-12,5220.100 8-119,4691,21351,6889331,
08973, 3095, 82061, 7291654,
6810-20.03227,877 11ω 0.700 7 1.51633
84.1512 c.

Aspherical surface (first lens surface) K: 0.000681. A4”-9,94079E-8
,AI,"3.48140E-9゜Aa"-4,25
177E-12, Ago”-2, 19691E-13 Aspherical surface (4th lens surface) K=-0.008230.A, =-7,75835E-
7, A6=-8,36471E-10As” 8.22
377E-12, Ago" 1.24482E 12 Aspherical surface (fifth lens surface) K = 0.005892.A, = 1.85277E-
6, A6 = 1.88925E-8゜Aa”-7,34
787E-10. Ago”-9,21327E-11 Aspherical surface (sixth lens surface) 4=0.007250.A,=-7,93987E-
f3. A6=-2,18937E-8゜Aa=-2,2
0873E-9, As. =-8,46198E-12 Example 12 F"43, FNO"3.0.2ω:40rid
ij 1” 19.333 7.049 12 13
2.885 2.335 23 38.029 0
．． 100 4" 16.001 2.755 5" 10.937 9.223 6" -10.0332,048 7-13,6160.100 8-91,3202,497 998,5785,702 10-20.33028, 239 11ω 0.700 12 ω Aspherical surface (first lens surface) K"-0.000843, A4" 1.67810E-
7, As” 3.24120E-9°A, =-3,99
137E-12, A engineering. =-1,92439E-135 51,7972025,31 , m=o, 1102 1.81600 46.60 1.79188 25.48 3 1.84700 23.90 4 1.84700 23.90 6 1.82588 44. 46 7 1.51633 64.15 Aspherical surface (4th lens surface) Bar: -0.018223, A4”-1,34881E-
6, Aa"-2,09675E-9Aa= 7.508
76E-11, A10 = 3.45634E-12 Aspherical surface (fifth lens surface) K = 0.011659. A4=2.62965E-
6, A6 = 3.45184E-8゜As” 1.90
774E-10. Aao”-5,86073E-11 Aspherical surface (6th lens surface)=0.013270.A,=-9,25722E-
6, A6=-4,32960E-8゜Aa"-2,24
801E-9tAl. , 5.84952E-12 or more 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 F=43, FNO=3.0.2c, +=40
, m=0.1102i rl di
j nj'l'j1'' 19.437
7.136 1 1.81600 46-622
108.313 2.562 2 1.84666.
23.893 39.469 0.100 4-field' 15.759 2.859 3 1.8
4666 23.8951110.875 9.339 6 8 -9.585 2.190 4 1.8
4666 23.897' -13,0460.1
00 8-116,8932,80851,8468B 2
3.899 182.869 5.944
6 1.81800 48.8210 -20.4
88 27.41811 oo O,7
0071,5163364,151200 Aspherical surface (first lens surface) K” 0.003324.A4”-1,66518E-
8, Aa" 3.38146E-9As=-4,738
32E-12, Ato"-1, 45951E-13 Aspherical surface (fourth lens surface) K"" 0.016745, A4"-1, 23940
E-6, As=-2,13549E-9Aa"-1,5
1576E-11, Ato” 1.91316E-12
Aspherical surface (fifth lens surface) "0.009973.A4" 2.46829E-
8, Aa"2.15292E-8Aa" 4.5109
3E-10. Ato"-7, 19133E-11 Aspherical surface (7th lens surface) K=-0.022285, Aa" 6.31684E-
6, As” 1.34122E-9Aa= 8.720
76E-10. At. =-2,40393E-12 Example 14 7 F"43, FNO"3.0. 2 (11
=40i ri di
Jl O 18.850 6.431 12
93.789 2.711 23
41.228 0.100 4” 15.077 3.1095”
10.587 9.371-B-8,9902,67
6? " -12,4320.100 8-128,8641,205 972,1095,822 10-20.11227,712 11oo 0.700 12 ω Aspherical surface (first lens surface) K = 0.000995.A4"-6 , 16372E-
8, As” 3.13143E-9゜Aa”-5,29
195E-12, Aao"-2,08012E-13 Aspherical surface (4th lens surface) K, -0.009178, A, = -8,62583E-
7, A6=-4,25198E-11Aa” 1.49
727E-11, At. = 8.97758E-138 51,6889331,08, m=0.1102 n5 νj 1.72916 54.68 1.78472 25.71 3 1.84666 23.89 6 1.72916 54.68 4 4.74077 27 .79 7 1.51633 64.15 Aspheric surface (fifth lens surface) K"0.008441.A4" 1.96162E-
6, At,” 1.79240E-8°Aa=-7,1
6441E-10. A10=-8,66460E-11
Aspherical surface (7th lens surface) K"-0.011185, A4" 4.63450E-
6, As”-6,92842E-9゜Aa” 5.42
505E40. Axo” 6.09409E-14 Example 15 F”13, FNO”3.0.2ω:40
, m=0.1102ir1d1jnj 1″19.318 7.018 1 1.81600
46.602 133.142 2.318 2
1.79289 25,453 38.019 0
．． 100 4” 15.975 2.767 3 1.84
700 23.905” 10.928 9.36
4 6 -9.885 2.040 4 1.8470
0 23.907" -13,3900.100 8-95,4142,4B9 5 1.79712
25.329 97.390 5.710 6 1
．． 82524 44.5910 -20.444.28
．． 117 11 oo O,70071,516336
4,159 12ω Aspherical surface (first lens surface) K=-0.000786, A4=-1,65499E-
7, As” 3.07778E-9゜Aa=-3,65
163E-12,A. =-1,85077E-13 Aspherical surface (4th lens surface) K” 0.018377, A4”-1,35139E-
6, A6”-2, 20155E-9A8” 6.276
06E-11, Alo" 2.89378E-12 Aspherical surface (fifth lens surface)" 0.011712. A4” 2.57627E-
6, AS” 3.87700E-8゜Aa” 2.31
274E40. A+o”-5,96410E-11 Aspherical surface (7th lens surface) K=-0.020982, A4=5.60059E-
6, A6 = 2.20429E-9゜Aa = 6.37
390E-10. A. =-2,94871E-12 or more is an embodiment of the lens of claim 5.

Figures 14, 15, and 16 show Examples 13 to 9, 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.

0 Since this lens is constructed as described above, the half angle of view is 2
It has a wide viewing angle of 0 degrees, has sufficiently high contrast even at high spatial frequencies of 71.4 lines/mm, and has a brightness of F.
It is bright as NO"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 regarding each example. io10, 1st lens, 12.10 2nd lens, 14
．． 10 third lens, 15.10 aperture, 16.10 fourth
Lens, 18.10 No. 1 Peripheral vomiting and laziness .5Y 0.25Y QNAX Engineering S Atsushi q Figure (Execution 4 row 6) -0.2000.2θ -0.200020-0.20
00.20 Wang Gumen l Nu and Astigmatism IX &
Distortion tt x, outside - (lnfuma l x derogation 9% t Figure (Execution 4 night old Eho surface 1 Nu right light L1 - Distortion 1 S difference (%) Tsuma aberration light 12 mouths (Execution 4 rows good) Coma LI x Difference 311- η℃ Toy 3 Kokoro (Real P!, 4th row I?) F/No, 3 Y=45?, 4 Y=4524 Silica eyes x Sitting silently breathing distortion convergence rz> Top Ll,

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 first, third, sixth, and eighth lens surfaces are aspherical, and the conic constants K_1 of these aspherical surfaces are
K_3, K_6, K_8 are (1-I)-0.02<
The condition that K_1<0.0 (1-II) 0.42<K_3<0.54 (1-III) 0.0<K_6<0.03 (1-IV)-0.18<K_8<2.0 A reading lens for scanners consisting of 7 elements in 5 groups, which satisfies the following. 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. 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. 6. The tenth lens surface is an aspherical surface, and the conic constant K_1 of these aspherical surfaces is
, K_3, K_6, K_1_0 are (2- I )-0.
015<K_1<0.0 (2-II) 0.04<K_3<0.8 (2-III) 0.0<K_6<0.03 (2-IV) -0.005<K_1_0<0.01 A reading lens for a scanner consisting of 7 elements in 5 groups, which satisfies the following conditions. 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 is a seventh lens which is a parallel plane glass. 8. The tenth lens surface is an aspherical surface, and the conic constant K_1 of these aspherical surfaces is
, K_3, K_8, K_1_0 are (3-I)-0.
015<K_1<-0.005 (3-II) 0.25<K
_3<0.65 (3-III) 4.0<K_8<14.0 (3-IV) -0.025<K_1_0<-0.015, 7 elements in 5 groups Reading lens for the configured scanner. 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. 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. 5. The sixth lens surface is an aspherical surface, and the conic constant K_1 of these aspherical surfaces is
K_4, K_5, K_6 are (4-I)-0.002
<K_1<0.005(4-II)-0.02<K_4<
-0.005 (4-III) 0.005<K_5<0.0
15(4-IV) 0.005<K_6<0.02 A scanner reading lens having a configuration of 7 elements in 5 groups, which satisfies the following condition. 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. 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. 5. The seventh lens surface is an aspherical surface, and the conic constant K_1 of these aspherical surfaces is
K_4, K_5, K_7 are (5-I)-0.002
<K_1<0.005(5-II)-0.02<K_4<
-0.005(5-III)0.005<K_5<0.0
15(5-IV)-0.025<K_7<-0.01 A reading lens for a scanner configured with 7 elements in 5 groups, characterized by satisfying the following condition: 15(5-IV)-0.025<K_7<-0.01.