Patent ID: 7164509

Claim:
An image reading device comprising: a support member; and a plurality of image sensor ICs mounted on the support member each having a plurality of light receiving elements arranged along a main scanning direction for receiving light reflected by an object to be read and outputting an image output signal while the object is being moved across the image sensor ICs in a sub-scanning direction, the image sensor ICs being divided into a plurality of blocks such that image signal outputs of each block are read during the same time period, and the image sensor ICs being arranged along the main scanning direction such that adjacent light receiving elements of adjacent image sensor ICs between the blocks are spaced from each other in the sub-scanning direction so that areas of the object which are to be read during the same time period in the sub-scanning direction are the same as each other; wherein adjacent light receiving elements of adjacent image sensor ICs between the blocks are spaced from each other in the sub-scanning direction by an amount K determined according to the following expression: K=(pitch of one line of movement of the object in the sub-scanning direction)×(start time of accumulation period of charge in a first one of the light receiving elements−start time of accumulation period of charge in a last one of the light receiving elements)/(period of one line movement of the object in the sub-scanning direction); and wherein the value of K is set in the range of: (pitch of one line movement of the object in the sub-scanning direction)×0.5≦K≦(pitch of one line movement of the object in the sub-scanning direction)×1.5.