| 摘要 |
PROBLEM TO BE SOLVED: To provide an image reading lens which is small in size, low in price and wide in angle of view and makes it possible to obtain optical performance suitable for reading images. SOLUTION: A first lens group G1, a second lens group G2 and a third lens group G3 are disposed, successively from an object side to an image side. A stop St is disposed between the second lens group G2 and the third lens group G3. The first lens group G1 comprises a positive lens of which the convex face is directed to the object side, the second lens group G2 comprises a negative lens of which the convex face is directed to the object side and the third lens group G3 comprises a positive lens of which the convex face is directed to the image side. Optical resins are used as the lens materials of the second lens group G2 and the third lens group G3. An aspheric surface is used for at least either of the second lens group G2 or the third lens group G3.
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