Image reading apparatus using a plurality of phase excitation modes

Claim 1

An image reading apparatus comprising: means for reading said image; a stepping motor for moving said reading means; means for generating a series of synchronizing signals; means for operating said stepping motor, said operating means operating in a plurality of phase excitation modes, with each mode of said modes operating said stepping motor for a different amount of movement for a selected synchronizing signal, said plurality of phase excitation modes being produced respectively by a 2 phase excitation driving circuit, a 1-2 phase excitation driving circuit and a W1-2 phase excitation driving circuit; means for designating a ratio for enlargement or reduction of said image read by said reading means; and means for selecting one of said plurality of phase excitation modes corresponding to said ratio designated by said designating means; said 2 phase excitation driving circuit driving said stepping motor when said designating means designates a reduction ratio; said 1-2 phase excitation driving circuit driving said stepping motor when said designating means designates a first enlargement ratio; and said W1-2 phase excitation driving circuit driving said stepping motor when said designating means designates a second enlargement ratio larger than said first enlargement ratio.