Kantatsu Co., Ltd.

Tohru Ishizaka

Masaya Hashimoto

An imaging lens for a solid-state image sensor includes five lenses, arranged in order from an object side to an image side, a first lens with positive refractive power having a convex surface on the object side, a second lens with negative refractive power, a third lens with positive or negative refractive power having a meniscus shape with a convex surface on the object side and a concave surface on the image side near an optical axis, a fourth lens as a double-sided aspheric lens, having a concave surface on the image side near the optical axis, and a fifth lens as a double-sided aspheric lens, having a concave surface on the image side near the optical axis; wherein the first to fifth lenses are made of plastic materials.

Imaging lens

A low-cost imaging lens which corrects aberrations properly with a small F-value, ensures high performance with a larger number of constituent lenses and has a more low-profile design than before. The constituent lenses are arranged in the following order from an object side to an image side: a positive (refractive power) first lens having a convex object-side surface near an optical axis; a positive second lens having convex object-side and image-side surfaces near the optical axis; a negative third lens having a concave image-side surface near the optical axis; a fourth lens having at least one aspheric surface; a meniscus fifth lens having a concave object-side surface near the optical axis; a sixth lens as a double-sided aspheric lens; and a negative seventh lens as a double-sided aspheric lens having a concave image-side surface near the optical axis. These constituent lenses are not joined to each other.

A low-cost imaging lens which corrects aberrations properly with a small F-value, ensures high performance with a larger number of constituent lenses and has a more low-profile design than before. The constituent lenses are arranged in the following order from an object side to an image side: a first lens having a convex object-side surface near an optical axis; a second lens having a convex object-side surface near the optical axis; a third lens having at least one aspheric surface; a fourth lens having at least one aspheric surface; a fifth lens as a double-sided aspheric lens; a sixth lens as a double-sided aspheric lens having a concave image-side surface near the optical axis; and a seventh lens as a double-sided aspheric lens having a concave image-side surface near the optical axis. These constituent lenses are not joined to each other.

A low-cost imaging lens which corrects aberrations properly with a small F-value, ensures high performance with a larger number of constituent lenses and has a more low-profile design than before. The constituent lenses are arranged in the following order from an object side to an image side: a first lens having a convex object-side surface near an optical axis; a positive second lens; a negative third lens having a convex object-side surface near the optical axis; a fourth lens having at least one aspheric surface; a fifth lens as a double-sided aspheric lens; a sixth lens as a double-sided aspheric lens; and a seventh lens as a double-sided aspheric lens having a concave image-side surface near the optical axis. These constituent lenses are not joined to each other.

An imaging lens includes five lenses for a solid-state image sensor, arranged in order from the object side to the image side, a first lens with positive refractive power having a convex object side surface, a second lens with negative refractive power having a concave image side surface, a third lens with positive or negative refractive power, a fourth lens with positive refractive power as a double-sided aspheric lens having a concave image side surface near an optical axis, and a fifth lens with negative refractive power as a double-sided aspheric lens having a concave image side surface near the optical axis, wherein the first lens and second lens satisfy conditional expressions below:45&#x3c;&#x3bd;1&#x3c;90&#x2003;&#x2003;(1)22&#x3c;&#x3bd;2&#x3c;35&#x2003;&#x2003;(2)2.0&#x3c;&#x3bd;1/&#x3bd;2&#x3c;2.6&#x2003;&#x2003;(3)

An image pickup lens includes, an aperture stop, a first meniscus lens having positive refractive power with a convex surface facing the object, a second lens having positive refractive power with a concave surface facing the object, a third lens having negative refractive power with a convex surface facing the object, the both surfaces of the third lens are aspheric and having at least one pole-change point, and following conditional expressions are satisfied:&#x3c;3.0&#x2003;&#x2003;(1)0.80&#x3c;1/&#x3c;0.93&#x2003;&#x2003;(2)0.35&#x3c;&#x3c;0.42&#x2003;&#x2003;(3)0.70&#x3c;/(2)&#x3c;0.85&#x2003;&#x2003;(4)where TTL: a length from the surface closest to the object to an image plane, f: a focal length of an overall optical system, f1: a focal length of the first lens, bf: a length from the image-side surface of the third lens to the image plane, and IH: a maximum image height.

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Sukagawa, Japan

Tohru Ishizaka