| US 7,535,660 B2 | ||
| Imaging lens | ||
| Tomohiro Saito, Kawaguchi (Japan) | ||
| Assigned to Enplas Corporation, Saitama (Japan) | ||
| Filed on Jul. 26, 2007, as Appl. No. 11/881,353. | ||
| Claims priority of application No. 2006-218123 (JP), filed on Aug. 10, 2006. | ||
| Prior Publication US 2008/0037139 A1, Feb. 14, 2008 | ||
| Int. Cl. G02B 9/06 (2006.01); G02B 15/14 (2006.01) | ||
| U.S. Cl. 359—794 [359/691] | 6 Claims |
| 1. An imaging lens used for forming an image of an object on an image-taking surface of a solid image sensor element, comprising:
in order from an object side to an image surface side, a diaphragm, a first lens which is a meniscus lens having a positive
power whose convex surface faces the object side, and a second lens which is a meniscus lens having a positive power whose
convex surface faces the image surface side, wherein a condition expressed by the following expression is to be satisfied:
1.45≤(r3+r4)/(r3−r4)≤3.4 (1)
where,
r3: center radius curvature of the object side face of the second lens
r4: center radius curvature of the image surface side face of the second lens; and wherein:
conditions expressed by following expressions (7) and (8) are to be further satisfied:
0.1≤d1/fl≤0.27 (7)
0.1≤d3/fl≤0.27 (8)
where,
d1: center thickness of the first lens
d3: center thickness of the second lens
fl: focal distance of the entire lens system.
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