Patent ID: RE41794

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