Patent ID: 6204937
Filing Date: 2001-03-20
Classification: H04N

Abstract:
A shielding device for use in an image reading device for reading a transmitting original, the image reading device having an transparent platform for holding the transmitting original, an illumination source to illuminate the transmitting original, and a linear photoelectric conversion device to read a linear portion of the image of the original at a selected position upon illumination of the original by the illumination source, the shielding device comprising:a light transmittance modification device positioned in the optical path between the illumination source and the linear photoelectric conversion device, said transmittance modification device being adapted to alter the transmittance of light passing therethrough corresponding to the linear portion of the original being read;a reading position modification device to modify the position at which the original is read by the conversion device;a storage unit to retain the reading position of the original read by the conversion device and the position of the edge of the original at the reading position; anda control unit to alter the transmittance of said light transmittance modification device in response to the position of the edge of the original at the reading position retained in the storage unit.