Image reading apparatus and scanner using photoelectric conversion unit with limited pixel count to read images with high resolution and method thereof

摘要

To read an image with high resolution via a CCD linear sensor having a limited pixel count, an image reading apparatus includes: a CCD linear sensor having arranged in a main-scanning direction photoelectric conversion elements for receiving a light reflected from an original; a piezoelectric element for providing a relative displacement between a light receiving surface of the CCD linear sensor and an object's image formed on the light receiving surface, according to a predetermined oscillation function and in the main-scanning direction; and a sensor drive circuit timing the CCD linear sensor's charge accumulation. The sensor drive circuit uses a distance from a center of an amplitude of the relative displacement to the CCD linear sensor and a time period of charge accumulation by the CCD linear sensor to determine a time point to start charge accumulation. The apparatus also includes a signal synthesizing circuit using image signals output from the CCD linear sensor during one period of the predetermined oscillation function to reconstruct an image signal of one line.