JPH03293611A - Read lens for scanner - Google Patents

Abstract

PURPOSE:To obtain the read lens for the scanner which is bright and has a wide field angle and superior resolving power by making a 5th, a 7th, and a 10th lens surface, counted from the object side, aspherical and specifying conic constants. CONSTITUTION:A 1st group consists of a 1st positive lens 10 and a 2nd negative lens 12 and a 2nd group consists of a 3rd meniscus lens 14 which has a convex surface on the object side. A 3rd group includes a 4th lens 16 which is a meniscus lens having a convex surface on the image side, a 4th group consists of a 5th negative lens 18 and a 6th positive lens 20, and a 5th group consists of a 7th lens 22 which is parallel plane glass. Further, a stop 15 is arranged between the 3rd lens 14 and 4th lens 16. The 5th, 7th, and 10th lens surfaces are made aspherical and the conic constants K5, K7, and K10 of those aspherical surfaces are specified as shown by inequalities. Consequently, the read lens for the scanner which has the wide field angle and high resolving power and is bright is obtained.

Description

[Detailed description of the invention] [Industrial application fields] 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.

The reading lens for a scanner is a lens for forming a reduced image of a document on a solid-state image pickup device in reading the document as described above.

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 recent years,
In view of the fact that the pixel size of solid-state image sensors is becoming smaller, high-resolution reading lenses for scanners are also required to enable high-resolution reading that takes advantage of the capabilities of solid-state image sensors. For example, C with one pixel size of 7 μm
In the case of a reading device using a CD, the reading lens for the scanner requires a resolution of 71.4 lines/mm on the light-receiving surface of the CCD, and high contrast for the above spatial frequency is required across the entire light-receiving surface. be done.

The tobogon type lens, which has been known for a long time as a lens suitable for a wide angle of view, has a flat radial image plane, and a tobogon type scanner reading lens that takes advantage of this feature has been proposed (for example, Japanese Patent Application Laid-Open No. 1983-1999). Publication No. 75721, 64
-23215 Publication).

[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. Furthermore, there is also the problem that the wider the angle of view, the greater the color breakup on the image plane, resulting in a decrease in contrast.

The present invention was made in view of the above-mentioned circumstances, and
Based on Tobogon type lens, bright with FNO"3,
The objective is to provide a new reading lens for scanners with a wide angle of view and excellent resolution.

[Means to solve the problem] 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 6 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.

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 group, which is a parallel plane glass.
The lens 22 is specifically 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 6 have in common that, in the above basic configuration, three lens surfaces are aspherical.

In the lens according to the first aspect of the present invention, the angle is 5° and 7° as counted from the object side. The tenth lens surface is an aspherical surface, and the conic constants of these aspherical surfaces are 5v K7t K10, (1-I)
0.0 < K5 <・0.018 (1-II)
−0,06<K,<0.0(1-III)
−0,004<K engineering. <0.024
satisfies the following conditions. 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 present invention, the angle is 5° and 8th, counting from the object side. The tenth lens surface is an aspherical surface, and the conic constants of these aspherical surfaces are 5*, 8*, and 10, (2-I)
0.0 < K5 < 0.025 (2-II)
0.0 < K8 < 20.0 (2-III)
−0,015<K,. The lens according to claim 3, which is characterized by the condition of <0.0, has an angle of 6° and a 7th angle as counted from the object side. The eighth lens surface is an aspherical surface, and the conic constants of these aspherical surfaces are Ks, K7. K8 is (3-I)
0.0 < K6 < 0.01 (3-II)
−0,017<K7<0.0(3-III)
The lens according to claim 4, which is characterized by the condition 0.0<K8<8.0, has an angle of 6 degrees and 7 degrees as counted from the object side. The tenth lens surface is an aspherical surface, and the conic constant of these aspherical surfaces is 6. K7. K10 is (4-I)
0.0. <K6< 0.011 (4-II)
−0,02<K7<0.0(4-II
I) The lens according to claim 5, characterized by the condition that 0.0023<Ksa<0.01, has an angle of 6 degrees and 8 degrees as counted from the object side. The 10th lens surface is an aspherical surface, and the conic constants of these aspherical surfaces are 6* Ks, KI O, (5-I)
0.0 < K6 < 0.033 (5-II
) 0.0 < Ks < 5.5 (5II
I) -0-007<Kin<0.0056
The lens according to claim 6 is characterized by the following conditions: 7th degree, 8th degree, counting from the object side. The tenth lens surface is an aspherical surface, and the conic constant of these aspherical surfaces is 71 Kae Kt o, (6-I)
−0,045<K,<0.0(6-II)
0.0 < K8 < 9.8 (6III)
The condition -0,004<K10<0.008 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 , the curve X・[CH2/(1+fF■1 block)]÷A2・H2
+A3・H3+A4・H'----・+Al0-H"+
- is a curved surface obtained by rotating around the optical axis, and the conic constant is K in the above formula.

[Function] The lenses according to claims 1 to 6 are all based on a tobogon 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 the problem of reduced 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, three lens surfaces are aspheric to achieve a larger aperture.

Generally, the larger the aperture, the thicker the 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.

Like the lens of claim 1, the fifth. 7th. When an aspherical surface is adopted as the 10th lens surface, the aspherical shape of the 5th lens surface that satisfies the condition (1()) is "an ellipsoidal surface that is rotationally symmetrical about the short axis."
, the aspherical shape of the seventh lens surface that satisfies condition (1-II) is "an ellipsoid that is rotationally symmetrical about the long axis", condition (1-III)
The aspherical shape of the tenth lens surface that satisfies the following is "an ellipsoid that is rotationally symmetrical about the major axis or the minor axis", and the condition (1-I),
The smallest coma flare can be achieved when (1-II) and (1-III) are satisfied.

Like the lens of claim 2, the fifth. 8th. When an aspherical surface is adopted as the 10th lens surface, the aspherical shape of the 5th lens surface that satisfies condition (2-I) is "an ellipsoidal surface that is rotationally symmetrical about the minor axis" and satisfies condition (2-II). The aspherical shape of the eighth lens surface is "an ellipsoidal surface rotationally symmetrical about the short axis", and the condition (2-III
The aspherical shape of the tenth lens surface that satisfies the conditions (2-I) and (2-I
I), the smallest coma flare can be achieved when (2-III) is satisfied.

Like the lens of claim 3, the 6th. 7th. When an aspherical surface is adopted as the eighth lens surface, the aspherical shape of the sixth lens surface that satisfies condition (3-I) is "an ellipsoidal surface that is rotationally symmetrical about the short axis."
, the aspherical shape of the seventh lens surface that satisfies condition (3-II) is "an ellipsoid that is rotationally symmetrical about the major axis", condition (3-III)
The aspherical shape of the eighth lens surface that satisfies is "an ellipsoidal surface rotationally symmetrical about the short axis", and conditions (3-I), (3-II)
, (3-III), the smallest coma flare can be achieved.

As in the lens of claim 4, the sixth aspect of the invention is as follows. 7th. When an aspherical surface is adopted as the 10th lens surface, the aspherical shape of the 6th lens surface that satisfies condition (4'-I) is "an ellipsoidal surface that is rotationally symmetrical about the short axis" and satisfies condition (4-II). The aspherical shape of the seventh lens surface is "an ellipsoidal surface rotationally symmetrical about the major axis", and the condition (4-II
The aspherical shape of the tenth lens surface that satisfies I) is "an ellipsoid that is rotationally symmetrical about the major axis or the minor axis" and satisfies condition (4-I).
), (4-II), and (4-III), the smallest coma flare can be achieved.

Like the lens of claim 5, the sixth. 8th. When an aspherical surface is adopted as the 10th lens surface, the aspherical shape of the 6th lens surface that satisfies condition (5-I) is "an ellipsoidal surface that is rotationally symmetrical about the minor axis" and satisfies condition (5-II). The aspherical shape of the eighth lens surface is "an ellipsoidal surface rotationally symmetrical about the minor axis", and the condition (5-III
) The aspherical shape of the tenth lens surface that satisfies the condition (5-I) is "an ellipsoid that is rotationally symmetrical about the major or minor axis."
, (5-H), (5(H)), the smallest coma flare can be achieved.

Like the lens of claim 6, the 7th. 8th. When an aspherical surface is adopted as the 10th lens surface, the aspherical shape of the 7th lens surface that satisfies condition (6-I) is "an ellipsoid that is rotationally symmetrical about the major axis" and satisfies condition (6-II). The aspherical shape of the eighth lens surface is "an ellipsoidal surface rotationally symmetrical about the short axis", and the condition (6-III
) The aspherical shape of the tenth lens surface that satisfies the condition (5-I) is "an ellipsoid that is rotationally symmetrical about the major or minor axis."
, (5-H), and (5-111), 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 6 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 embodiment, as shown in FIG.
The radius of curvature of the lens surface (on-axis radius of curvature for aspherical surfaces) is rl (1・1~12), the interval between the jth lens surfaces is d, (i=1~11), the jth lens surface is Let the refractive index and Abbe number of the lens be nl, ν, and (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.

Aspherical surfaces are marked with *, and in addition to the axial radius of curvature, the conic constant and the higher-order aspherical coefficient A4. A61A8. A10 is given to specify the aspherical shape.

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 I F=43, FNo”3.0.2ω=40
, m=0.11021r + d r j
n,, ν.

1 19.119 7.062 1 1.8160
0 46.622 107.283 2.197
2 1.84666 23.893 35.014
0.369 4 13.274 2.324 3 1.8466
6 23.895" 9.878 10.236 6 -8.794 1.920 4 1.8466
8 23.897" -11,2790,444 8-85,9092,27451,8466623,8
99183, 2915, 62961, 8160046,
6210"-20,39627,19211(X)
0.700 7 1.51633 64
．． 1512 (X) Aspherical surface (fifth lens surface) K= 0.001889. A4=7.15678E-
7, A6=-1,33849E-8As"-3,861
99E-10, A10" 8.41263E-12 Aspherical surface (7th lens surface) K knee 0.003387. A4" 2.09040E
-6,As”-1,83871E-9゜AM=9.0
1466E-11, Al0= 1.23099E-13
Aspherical surface (10th lens surface) K knee 0.003626. An” 1.47914E-
7,As”-4,04785E-10As”3,98
548E (2, A10" 1.72654E-14 Example 2 F=43, FNo: 3.0.2ω=40
, m=0.11021 r, di j
nj vjl 18.916 5.75
7 1 1.72916 54.682 106.
329 1.812 2 1.78472 25.7
13 44.599 0.100 4 13.501 3.201 3 1.8466
6 23.895″ 9-523 10.067 6 -11.047 3.549 4 1.7
4077 27.797" -16,6480,1
00 8-137,4921,00051,6889331,
08985, 9215, 59661, 7291654,
6810"-19,68328,69611(X)
0.700 7 1.51633 64.
1512 (X) Aspherical surface (fifth lens surface) K= 0.007394. A4 = 1.25200E-
6, A6 = 6.61487E-8°As”-1,57
137E-9, A10" 1.88280E-11 Aspherical surface (7th lens surface) K=-0,058514, A4= 1.18779E-
5, A, = -3,24537E-8°A8 = 5.47
198E-10, A10=-1,00280E-11 Aspherical surface (first O lens surface) K" 0.021857. A4"-9,15680E
-7,A(1"-4,93179E-9°A, = 1.
29258E-10, AI. = 2.54692E-1
3 Example 3 F: 43, FNo: 3.0, 2 ω=40
, m=o, 11021ridi
j n; ν.

1 19.448 6.951 1 1.8
1600 46.602 113.823 2.0
91 2 1.82265 24.553 3
7.622 0.100 4 14.130 2.546 3 1.8
4700 23.905' 10.057 9
．． 8498 -10.822 2.283 4
1.84700 23.907' -14,97
30,100 8-88,0942,15851,7855625,7
0991,2255,39561,8274644,1
510”-20,22728,66911Q)
0.700 7 1.51633 64.15
12 C0 Aspherical surface (fifth lens surface) K= 0.016545. A4 = 3.97319E-
6, A6 = 4.31185E-8° A8 = -4,48
321E-10, A1o= 1.36753E-11 Aspherical surface (7th lens surface) K"-0,024665,A4" 6.55621E-
6, A6”-6,45422E-9°A8=3.75
727E-10, A,, = -1, 18497E-11 Aspherical surface (10th lens surface) K = 0.001375. A, = 7.85275E-
8, AA=-4,04938E-9°A8=5.29
071E-11, A, o=2.38164E-13 or more are examples of the lens of 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 dashed line indicates Example 4 F=43. FNo=3.0, 2ω:401m=0.11
02i r , d lL]n = ν41
19.162 7.083 1 1.81600
46.622 106.495 2.239 2
1.84666 23.893 35.397 (
L308 4 13.428 2.326 3 1.8466
6 23.895" 9.940 10.199 6 -8.852 1.941 4 1.8468
6 23°897 -11.380 0.346 8" -87,4822,24351,846662
3,899182,2015,58461,81600
46,8210" -20,44727,371 11's 0.700 7 1.51633 64.
1512c.

Aspherical surface (fifth lens surface) K” 0.003961.A4” 1.27207E
6. Ac”-1゜04304E-8A8=-4,596
20E-10,A. = 1.12203E-11 Aspherical surface (8th lens surface) K” 1.752941.A4”-3,83584E-
7, A1. "5.45544E-10As" (,24
515E-12, A10" 1.30182E 13 Aspherical surface (10th lens surface) K"-0,009170, A4" 4.81583E-
7,A6:-2,10302E 9゜A8:2.765
31E-12,A. = 3.97967E-14 Example 5 F1a, FNO"3.0, 2 ω40
, m=0.1102s ri ai
j nj ν.

1 18.928 5.829 1 1.7291
6 54.682 110.963 1.968
2 1.78472 25.713 43.142
0.100 4 13.833 3.175 3 1.8486
6 23.895" 9.868 10.042 6 -9.809 2.867 4 1.7407
7 27.797 -13.761 0.100 8" -114,3011,00051,68893
31,08988,5815,40061,72916
54,6810" -19,92628,440 11■ 0.700 7 1.51633 64.
1512 c.

Aspherical surface (fifth lens surface) K= 0.006130. A, = 1.51805E-
6, A6 = 2.46375E-8°A8 = -1,77
470E-9,A. = 2.44009E-11 Aspherical surface (8th lens surface) K"19.607012.A4" 2.83882E-
6, As” 5.57269E-9゜A8=2.70
663E-11,A. = 7.08662E-13 Aspherical surface (10th lens surface) K=-0,008714, A4= 1.26396E-
6, A6=-1,62165E-8°As” 6.14
114E (2, A+n” 5.21169E 13 Example 6 F: 43, FNo: 3.0.2ω40,
m=0.11021rid;
J nJ νJ1 19.467 6.
795 1 1.81600 46.602 10
9.012 1.934 2 i, gz10g
2tp, 593 38.042 0.100 4 15.125 2.779 3 1.8470
0 23.905” 10.519 10.042
6 -10.576 2.197 4 1.847
00 23.907 -14.470 0.100 8" -86,3161,5505i, 778 outside 2mm q+9 80.806 5.218 6 18g3
+33 ri, 3ㅅ10” -20,2962L823 11 (X) 0.700 7
Aspherical surface (fifth lens surface) of 1.51633 64.1512 K= 0.023282. A4 = 5.06346 -
6, As” 6.53471E-8°A8=-6,57
532E-10, A1o = 2.27528 to 111 aspherical surface (8th lens surface) K” 9.891244.A4”-2,12059E-
6, A6"4.86772E-9゜As" 3.57
060E-11, A1゜= 1.12281E-12 Aspherical surface (10th lens surface) K=-0,013558, A4= 1.33531E-
6, A, = -1,57041E-8°A8 = 6.29
131E-12, A, o=5.81427E-13 or more is an embodiment 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"40
, m:0.1102! “i ai
j nj ν.

19.099 7.057 1 1.81600 4
6.62108.857 2.184 2 1.84
666 23.893 34.826 0.39
5 4 13.181 2.330 3 1.8
4666 23.895 9.834 10.2
68 6' -8,7751,91441,848862
3,897" -11,2470,473 8" -85,3542,29451,84666
23,899185,2815,65561,8160
046,6210-20,37427,042 11ω 0.700 7 1.5]633 6
4.1512 CX) Aspherical surface (6th lens surface) K= 0.001040. A4=-2,37194E-
6, A6= 1.20985E-8°A8=-2,41
861E-10,A, n=-3,82890E-12
Aspherical surface (7th lens surface) K knee 0.002098. A4” 1.39271E
-6,As”-7,41447g-9゜As”6.5
7063E (1, A10" 1.59359E-12 Aspherical surface (8th lens surface) K" 0.419512. A4"-8, 48012E
-8,As”-1,09915g-9゜A8=-1,1
3771E-11,A. = 9.25927E-14
Example 8 F: 43, FNO"3.0, 2 ω: 4
0, m=o, 11021rid
t j J ν,.

1 19.019 5.930 1 1
．． 72916 54.682 119.810
1.927 2 1.78472 25.713
43.325 0.1004 12.8
17 3.021 3 1.84666 23
．． 895 9.295 10.364 6” -10,7993,36741,74077
27,797' -16,2510,100 8" -117,2431,00051,68893
31,08997,6315,87361,72916
54,6810-19,13028,199 11CoO,70071,5163364,
1512 (1) Aspherical surface (sixth lens surface) K = 0.009672. A4=-1,21815E-
5, A6 = 3.16324E-8゜Aa = -1,85
865E-9, A6, K7, K10 = 6.31628
E-11 aspherical surface (7th lens surface) K=-0,015494, A4=5.29721E-
6, A6=-5,21519E-8゜A8" 3.83
336E 10. Ago: 2.23575E-12 aspherical surface (8th lens surface) K" 7.226461. A4" 9.76282
E-7, As”-1, 50345E-8゜A6=-1,
03683E-10, Ago:8.88170E-13
Example 9 F; 43, FNo; 3.0, 2 ω: 40
, m=o, 11021 r; d
lJ nJ1'=1 19.997 6.840
1 1.81600 46.602 139.5
04 2.000 2 183362 24.253
38.382 0.100 4 13.380 2.656 3 1.8470
0 23.905 9.810 10.289 6” -10,8082,46641,847002
3,907″-15,3100,105 8″-95,0442,29951,7918125
,499128,3995,63261,817644
6,2310-19,86728,447 11Co O,70071,5163364,15
12(X) Aspherical surface (6th lens surface) K” 0.008782.A4”-9,52330E-
6,4a” 2.93735E-8゜As”(,700
10E-9, Ago" 4.09585E-11 Aspherical surface (7th lens surface) K=-0,015731, A4" 4.94834E
-6,Aa"-3,95530E 8゜As" 4.3
5066E (0, A10" 1.00009E-12 Aspherical surface (8th lens surface) K" 2.144453. A4"-3,86737E
-7,A6"-1,30086E-8As" 1.15
978E40. At. = 9.39711E-13 or more are examples of the lens of 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=o, 11021 r; dt
J n= ”jl 19.087 7.
051 1 1.81600 46.622 10
8.104 2.173 2 1.84666 23
．． 893 34.717 0.416 4 13.208 2.329 3 1.8466
6 23.895 9.858 10.302 6” -8,7061,90441,846662
3,897” -11,1310,483 8-85,3142,28751,8466623,8
99178, 8995, 64761, 8160046,
6210”-20,39927,02111
0.700 7 1.51633 64.15
12 ■ Aspherical surface (6th lens surface) K= 0.000927. A4=-2,04908E-
6, A6 = 5.22744E-9As” 2.707
31E-10, A10”-2, 36127E-12 Aspherical surface (7th lens surface) K=-0,001829, A4 = 1.19009E
-6,A6=-4,25771E-9゜A8=6.7
7462E-11,A. = 9.82376E-13
Aspherical surface (10th lens surface) K=0.002011. A4” 8.61803E-8
, AS"-3,52105E-10As" 2.976
25E 12. At o” 1.92691E-14
Example 11 F=43 FNo=3.0, 2ω=40,
m=o, 1102 i rid,
j nj ν.

1 18.997 6.033 1 1.7291
6 54.682 115.914 2.121
2 1.78472 25.713 42.595
0.100 4 13.008 3.003 3 1.
84666 23.895 9.446 10.
316 8”-10,4183,24541,74077
27,797" -15,2720,100 8-106,0781,00051,6889331,
08989, 7755, 95061, 7291654,
6810"-19,14928,02311Cx:
10,70071,5163364,1512CX) Aspherical surface (sixth lens surface) K = 0.008676, A, = -1,39556E-
5, A6 = 1.30289E-8As2 3.258
80E 9, Ago” 6.01102E-1
1 Aspherical surface (7th lens surface) K=-0,016912, A4=5.66697E-
6, A, = -2,88749E-8゜As” 5.85
325E-10, Ago”-2, 05649E-12 Aspherical surface (10th lens surface) K” 0.009308. A4”-5,02743
E-7,As”-1,09600E-9°As=7.6
4157E-11, Ago” 2.48346E-14
Example 12 F=43. FNo: 3.0, 2ω=409m=0.11
021 r, d; J
n・ 1゛1 19.893 6.86
7 1 1.81600 46.602 138
．． 639 2.010 2 1.83104 2
4.323 38.132 0.100 4 13.336 2.633 3 1.8
4700 23.905 9.769 10.2
68 6”-10,8812,42941,84700
23,907′″ -15,3640,108 8-91,5252,50851,7902425,5
49116, 6555, 78361, 8191845,
8910'-19,87828,28911Co
O,7007L51633 64.1512
C0 Aspherical surface (sixth lens surface) K=0.010376, A4”-1,04740E-5
, A6" 1.47301E-8°A, = -2,795
10E-9,A. , 3.67139E-11 Aspherical surface (7th lens surface) K=-0,019596, A4= 5.28347E-
6, A, 1=-2,14645E-8°As” 5.9
7745E 10. Ato”-5,23690E 12
Aspherical surface (first O lens surface) = 0.002033. A4=3.91862E-
8, A6=-3,45183E-9°As” 5.10
758E-11, AI. = 1.09521E-13 or more is an embodiment of the lens according to claim 4.

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

Example 13 F=43 1 rj 1 19.121 2 109.858 3 34.956 4 13.120 5 9.792 6" -8,823 7-11,323 8" -85,224 9186,672 10" -20,361 11 of 12 C0 1,8466623,89, m=0.1102 nj vj 1.81600 46.62 1.84886 23.89 1.84666 23.89 1.84666 23.89 1.81600 46. 62 1.51633 64.15, FNo”3. o, 2ω: 40 d・J 7.059 1 2.190 2 0, 389 2.320 3 10.259 1.924 4 0, 460 2.297 5 5.654 6 27.077 0.700 7 Aspheric surface (Sixth lens surface) K=0.002298. A4=-3,75662E-
6, A6 = 1.09485E-8As”-2,673
97E-10, A to”-5, 97442E-12
Aspherical surface (8th lens surface) K= 0.505806. A4=-1,03451E
-7,A6=-6,52948E-10A8=-8,1
0472E-12, At0=1.32133E-13
Aspherical surface (10th lens surface) K=-0,003834, A4= 1.87636E-
7,A,=-8,89094E-10As:2.388
02E-12, At. = 3.51256E-14 Example 14 F=43, m=o, 1102 n, ν.

1.72916 54.68 1.78472 25.71 FNo: 3.0, 2ω=40 d, J 6.090 1 2.101 2 0, 100 2.965 3 10.203 3.376 4 0, 100 1 .000 5 1 r 7407727,79 1,6889331,08 993,9615,87961,7291654,68
10”-19,00828,2941101)
0.700 7 1.51633 64.
1512 aspherical surface (sixth lens surface) K=0.029767, A4”-2,08536E-5
,AS"2.31743E-8As"2.07172
E-9, A10 = 2.83041E-11 aspherical surface (8th lens surface) K = 5.018862. A4=-7,89520E
-7,A6=-4,92106E-9゜As” 4.6
1039E (1, Ato” 8.07743E-13 Aspherical surface (10th lens surface) K” 0.005079.A4” 1.71387E-
7, Aa"-9,67937E-9°A, = 4.81
778E-11, A engineering. = 3.50181E-13 Example 15 F=43. FNo; 3.0, 2ω=409m=0.11
02rid, j nj ν4
19.423 7.022 1 1.81600 4
6.60122.888 2.150 2 1.83
794 24.1336.291 0.100 13.118 2.419 3 1.84700 2
3-905 9.689 10.098 6” -10,1002,12941,84700
23,907-13,6210,305 8”-87,0712,46651,80751
24,999118,6275,73761,8208
845,5210"-20,13627,9311
1 (1) 0.700 7 1.5163
3 64.1512 ■ Aspherical surface (6th lens surface) K"0.010820.A4" 1.09485E-
5, As” 2.03808E-8゜Aa”-9,58
200E-10, Ato” 7.61072E-12 Aspherical surface (8th lens surface) K= 1.723152. A4=-3,45611E
-7,A6=-3,56754E-9A8=-3,08
531E-11,A. = 7.61874E-13 Aspherical surface (10th lens surface) K"-0,006288,A4" 4.36345E-
7, A6”-4,13275E-9°A, = 1.6
4349E-11,A,, = 1.83622E-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.

Example 16 F43, FNO"3.0, 2 ω40
, m=o, 11021 r+ d+
J nj ν.

1 19.265 7.091 1 1.8160
0 46.622 111.713 2.257
2 1.84666 23.893 35.9060
．． 102 4 13.113 2.366 3 1.8466
6 23.895 9.731 10.165 6 -9.429 2.054 4 1.8466
6 23.897" -12,4460,320 8" -90,5802,39551,846662
3,899211,4235,72361,81600
46,6210''-20,22527,45511
ω 0.700 7 1.51833 64.15
12 c.

Aspherical surface (7th lens surface) K”-0,009640,A4” 4.84532E
6. As”-1,81133E 8A8= 1.10
706E-10, At. = 5.64763E-13 Aspherical surface (8th lens surface) K = 1.461556. A4 = -2,94310
E-7, A6=-2, 70279E-9°A8=-1,
97545E-11, A10=5.40048E-1
3 Aspherical surface (10th lens surface) K"-0,003859, A4" 2.59481E
-7,As”-2,50247E-9゜As”1.
13729E-11, Ato2 1.18888E-1
3 Example 17 F-43F10"3.0, 2 ω:40, m
:o, 11021 rl(L J
nj vjl 19.231 6.043
] 1.72916 54.682 119
．． 652 2.025 2 1.78472 25.
713 44.003 0.100 4 12.896 2.989 3 1.8466
6 23,895 9.349 10.261 6 -10.841 3.349 4 1.740
77 27.797" -15,7900,100 8" -123,5141,00051,68893
31,08987,3165,76361,72916
5L6810"-19,42628,393110
Aspherical surface (7th lens surface) of 00,70071,5163364,1512 K=-0,041284,A4=1.00209E-
5,A,=-4,28802E-8As:8.1954
4E-11,A. =-3, 20187E-12 Aspherical surface (8th lens surface) K= 8.933672. A4=-1,20440E
-6,A6=-7,98616E-9゜As"-4,1
0231E-11, A1゜=8.65769E-13
Aspherical surface (10th lens surface) K= 0.007296. A4=-2,40157E
-7,A6”-6,03055E-9゜A8=6.4
3980E-11,A. = 3.71533E-13
Example 18 F: 43, FNO"3.0, 2 ω=40
, m=0.1102i r・d・
J nj ν.

1 19.071 7.019 1 1.81600
46.602 115.046 2.122 2
1.84466 23.963 34.613 0
．． 384 4 13.150 2.328 3 1.8470
0 23.905 9.802 10.225 6 -8.948 1.909 4 1.8470
0 23.907" -11,5450,428 8" -86,7752,28951,832222
4,299135,1285,82781,81835
46,0710" -20,41327,34111
(X) 0.700 7 1.51633
64.1512 (X) Aspherical surface (7th lens surface) K=-0,003665, A4= 2.36114E-
6, A6=-9,79600E-9°As” 3.43
840E-11, Ato" 1.27313E-12 Aspherical surface (8th lens surface) K= 0.585013. A4=-1, 19691E
-7,A,=-7,29178E-10A8=-7,6
9022E-12,A. = 1.63474E-13
Aspherical surface (10th lens surface) K=-0,002946, A4= 1.57683E-
7, A6=-9,65135E-10A8=3.04
789E-12,A. =4.07384E-14 or more is an embodiment of the lens according to claim 6.

Examples 16 to 17 are shown in FIG. 17, FIG. 18, and FIG. 19, respectively.
18 is shown.

Aberrations are good 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 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 lens configuration of the present invention, and FIGS. 2 to 19 are aberration diagrams regarding each example. 10., first lens, 12. ,, second lens, 14.
, ,Third lens, 15-, ,Aperture, 16. ,,4th
Lens, 18. , 5th lens, 20. , , 6th lens, 22. , , 7th lens / 圀〃MoZl (large 4P1 chiδ ka (large light example oligoferonate 511 curved ΔE tokinokoma aberration rate 4 figure (large fJσ) F/No, 3 Y = 1524 and = 64 Taste surface aberration 弗 Gradual grain distortion Vl (Term dicoma yield Chi D Mouth (Example 4; Taste" surface difference intercharacter aberration distortion yield (-/, Nocoma aberration F/AJσ3 and = 1524 Y=. 1 θ θ θ θ - θJ θ ρW −σ0 and / f2.4 W Chi70 (Husband, right?”J6 Spherical aberration: # point aberration distortion surface aberration! (〃Nocoma aberration form δ 7 F/No, 3 Y = 152.4 and = σZ4 spherical yield upoint aberration distortion can (phantom example 7) 'γ・2 coma aberration 9 shaku (lol light example 3 F fake, 3 and = Revised A Y - Jf2.4 Astigmatism on the closed surface! Distortion solar aberration (B-Nokoma aberration type 40 squares (arrow) 7?,, fJ'/F/IJ0.3 γ-15Z, 4 Y= 15Z, 4 Spherical yield astigmatism! is yield 2 t (ton) ko? convergence form (-℃ force τ → column good F/no3 Y-!52.4 and =!52.4 spherical yield 1 7F-point l Distortion convergence (/,) Comatic aberration F/Na3 γ= Jf2.4 1440 (Large fJ 1δ2 Y-J5Z, 4 6ha% IG factor (ShinyI 4 rows 4Q) Comatic aberration ! Spherical convergence absorption convergence 7ta 470 (Tora-jo example 4C) j Mi @ aberration (f, Nkoma IIX' Mugi F/No, 3 Y=!524 1θJ 0m −〇J 0, J −〇? 16 Figure (Oshima example q) Figure 19 (Osai, ?1n F/10, 3 Y= J5Z, 4 Y= J5Z, 4 Spherical aberration Point convergence Ax distorted spear ('/,) Comatic 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 5th, 7th, and 10th lens surfaces are aspherical, and the conic constants of these aspherical surfaces are K_5, k_
7.K_1_0 becomes (1-I)0.0<K_5<0.018 (1-II)-0.06<K_7<0.0 (1-III)-0.004<K_1_0<0.024 A reading lens for scanners consisting of 7 elements in 5 groups, which satisfies the following conditions. 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. The tenth lens surface is an aspherical surface, and the conic constants K_5, K_ of these aspherical surfaces are
8. Condition for K_1_0 to be (2-I)0.0<K_5<0.025 (2-II)0.0<K_8<20.0 (2-III)-0.015<K_1_0<0.0 A reading lens for scanners consisting of 7 elements in 5 groups, which satisfies the following. 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. The eighth lens surface is an aspherical surface, and the conic constants of these aspherical surfaces are K_6 and K_7.
, K_8 is (3-I)0.0<K_6<0.01 (3-II)-0.017<K_7<0.0 (3-III)0.0<K_8<8.0 A reading lens for scanners with a configuration of 7 elements in 5 groups, which is characterized by satisfactory characteristics. 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 is a seventh lens which is a parallel plane glass. The tenth lens surface is an aspherical surface, and the conic constants K_6, K_ of these aspherical surfaces are
7.K_1_0 becomes (4-I)0.0<K_6<0.011 (4-II)-0.02<K_7<0.0 (4-III)-0.0023<K_1_0<0.01 A reading lens for scanners consisting of 7 elements in 5 groups, which satisfies the following conditions. 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 group is a seventh lens which is a parallel plane glass, and counting from the object side, the sixth, eighth, and The tenth lens surface is an aspherical surface, and the conic constants K_6, K_ of these aspherical surfaces are
8, K_1_0 is (5-I)0.0<K_5<0.033 (5-II)0.0<K_8<5.5 (5-III)-0.007<K_1_0<0.0056
A reading lens for a scanner consisting of 7 elements in 5 groups, which satisfies the following conditions. 6. 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 group is a seventh lens which is a parallel plane glass, and counting from the object side, the seventh lens, the eighth lens, and the sixth lens are made of parallel plane glass. The tenth lens surface is an aspherical surface, and the conic constants K_7, K_ of these aspherical surfaces are
8.K_1_0 becomes (6-I)-0.045<K_7<0.0 (6-II)0.0<K_8<9.8 (6-III)-0.004<K_1_0<0.008 A reading lens for scanners consisting of 7 elements in 5 groups, which satisfies the following conditions.