Patent ID: 6771408
Filing Date: 2004-08-03
Classification: G02B,G03B,H04N

Abstract:
An optical lens device of image scanner may receive the optical image reflected from a document and focuses the optical image into an image on an image induction element, and the optical lens device comprising:a diaphragm; and plural lenses, which are arranged linearly with the diaphragm and the induction element for defining an optical path between the document and the image induction element wherein, according to the different positions between the lens and the diaphragm, the plural lenses may be divided into two groups; i.e., the front group lens is located between the diaphragm and the document, and the back group lens is located between the diaphragm and the image induction element; wherein, among the plural lenses, the one that is most close to the document is called the first lens, while the other one that is most close to the image induction element is called the last lens, and the distance that is between the last lens and the image induction element is abbreviated as BFL, and the length, of the induced image, provided by the image induction element is called the image height, and the distance between the document and the image induction element is abbreviated as TT, and the effective focus length of the optical lens device is abbreviated as EFL; wherein, the ratio between the diameter of the last lens of the optical lens device and the diameter of the first lens is greater than one; that is, the diameter of the last lens/the diameter of the first lens>1.