ROD LENS ARRAY FOR LINE SCANNING

摘要

PROBLEM TO BE SOLVED: To provide a rod lens array for line scanning with which the deterioration of image quality (vertical stripe in a subscanning direction on an outputted image) caused by the cyclic irregularity of light quantity is made inconspicuous by considering an aperture angle and the positional deviation of an image line in the subscanning direction. SOLUTION: A rod lens array 2 for unmagnified image-formation where plural pieces of columnar rod lenses 1 having refractive index distribution in a radial direction are arrayed in a line in a main scanning direction so that their optical axes 1a may be parallel with each other is used as the rod lens array for line scanning. Assuming that the diameter of the rod lens 1 is (d) and the array pitch of the rod lens 1 is (D), the range of an effective overlapping degree (m) is set as shown by the following expression. (1.55+0.5j) D/d<=m<=(1.80+0.5j) D/d.