| 摘要 |
PROBLEM TO BE SOLVED: To reduce the cost of an imaging lens to be used for a camera for recongnizing a packaging machine. SOLUTION: The lens has the arrangement of, successively from the object side to the image plane side: a plano-convex first lens 1 having positive refractive power and having the convex face S1 in the object side; a meniscus-shaped second lens having positive refractive power and having the convex face S3 in the object side; a plano-concave third lens 3 having negative refractive power and having the planar face S5 in the object side; an aperture diaphragm 5 having a specified aperture size; and a plano-convex fourth lens 4 having positive refractive power and having the convex face S8 in the object side. In the four-group four-lens structure, lens faces requiring substantial processing are reduced, which results in an inexpensive imaging lens satisfying specified optical performance. COPYRIGHT: (C)2005,JPO&NCIPI
|
