Patent ID: 6721073
Filing Date: 2004-04-13
Classification: H04N

Abstract:
An image input device, comprising:a linear image sensor provided with a plurality of linearly arranged light receiving elements for outputting an image signal of a linear image formed on the light receiving element; an image forming optical system for forming an image of a linear area on an original onto a row of the light receiving elements of said linear image sensor; a sub-scanning mechanism for moving said linear area formed into the image on said linear image sensor to scan the entire image of the original by the linear image sensor; a lighting light quantity detecting section for outputting a lighting light quantity signal indicative of a voltage corresponding to a lighting light quantity radiating to the original; a correction voltage adding section for adding a correction voltage to at least one of said lighting light quantity signal and said image signal to eliminate an influence by nonlinearity of a photoelectric conversion property of said linear image sensor and the lighting light detecting section; and a correcting section for eliminating a voltage fluctuation by a fluctuation of the lighting light quantity of said lighting light quantity signal, the image signal with or without said correction voltage added thereto based on the lighting light quantity signal without or with said correction voltage added thereto, wherein said correction voltage adding section comprises one of a first voltage adding circuit for adding a first voltage to said lighting light quantity signal to eliminate the influence by the nonlinearity of the photoelectric conversion property of said linear image sensor and the lighting light detecting section, and a second voltage adding circuit for adding a second voltage to said image signal to eliminate the influence by the nonlinearity of the photoelectric conversion property of said linear image sensor and the lighting light detecting section, wherein said correcting section comprises a division circuit for using said lighting light quantity signal as a denominator input and the image signal with said second voltage added thereto as a numerator input to perform division when said correction voltage adding section comprises a second voltage adding circuit, or using said lighting light quantity signal with said first voltage added thereto as a denominator input and the image signal as a numerator input to perform division when said correction voltage adding section comprises a first voltage adding circuit.