Patent ID: 8531530
Filing Date: 2013-09-10
Classification: G02B,H04N

Abstract:
1. An adjusting method for a lens unit usable in an image reading apparatus that forms images of an original onto one-dimensional photoelectric transducers using the lens unit and reads image information of the original, the lens unit including a plurality of rotationally-symmetrical lenses, a lens barrel including the plurality of rotationally-symmetrical lenses and an adjusting lens disposed at an end portion of the lens barrel, the adjusting method comprising: a rotational adjustment step of rotational adjusting the lens barrel with respect to the adjusting lens by rotating the lens barrel around symmetry axes of the plurality of rotationally-symmetrical lenses; and a contrast depth characteristics obtaining step of obtaining contrast depth characteristics of images of a chart formed on the one-dimensional photoelectric transducers corresponding to at least three angles of field of the lens unit; and a positional adjustment step of, according to the contrast depth characteristics obtained in the contrast depth characteristic obtaining step, adjusting a position of the adjusting lens with respect to the lens barrel in at least one of an array direction of the one-dimensional photoelectric transducers, an optical axis direction of the lens unit, or a direction perpendicular to the array direction and the optical axis direction.