Patent attributes
An imaging lens includes, in order from the object side: a first lens component of negative refractive power with two aspheric surfaces including a concave surface near the optical axis on the image-side; a second lens component of positive refractive power with a convex surface on the object side; a third lens component having positive refractive power and including lens elements having positive and negative refractive powers; and a fourth lens component having an aspheric surface on the image side that is convex near the optical axis and is concave at the periphery. The imaging lens satisfies a specified condition to assure a sufficient back focus for insertion of additional optical elements, a sufficiently small imaging lens diameter, and favorable correction of aberrations. The imaging lens has a wide picture angle, consists of only 5 lens elements in the disclosed embodiments, and is particularly suited for a text imaging camera.
