READ LENS FOR SCANNER

Japanese Patent JPH03191309

A

PURPOSE:To realize this read lens for a scanner which is bright and has a wide view angle and superior resolving power by using aspherical lens surfaces as a 3rd and a 7th lens surface which are counted from an object side and forming five-group, seven-piece constitution wherein the cone constants of the aspherical surfaces satisfy specific conditions. CONSTITUTION:A 1st - a 5th group are arrayed in order from the object side to the image side and a diaphragm 15 is arranged between the 2nd group lens 14 and 3rd group lens 16 to form the five-group, seven-element constitution. Then the 3rd lens 14 and 7th lens 22 which are counted from the object side have the aspherical surfaces, whose cone constants K3 and K7 satisfy the conditions of 0.03