Patent ID: 7095149

Claim:
A magnetization pattern of a rotor magnet for a stepping motor, comprising: a plurality of magnetized portions formed along the direction of rotation of the rotor magnet, wherein the magnetized portions have opposing magnetic poles which are alternately arranged on the rotor magnet; some of the magnetized portions are of width A; each magnetized portion of width A is opposed to another magnetized portion of width A with the center of revolution of the rotor magnet interposed between each set of two opposed magnetized portions of width A; each of the magnetized portions not of width A is of uniform width B; and width A is greater than width B; and a total pole number of all the magnetized portions formed on the rotor magnet is defined as y, an angle obtained by dividing 360° by the total number of poles y is defined as x°, an arbitrary angle is defined as a°, a total number of said magnetized portions having the magnetization widths A is defined as z, a center angle with respect to each of the magnetization widths A of said magnetized portions is defined as A°, and a center angle with respect to each of the uniform widths B of said magnetized portions is defined as B°, the following equations are satisfied, A°=x °+( y/z− 1) a°; B °=( x°−a °); x °+( y/z− 1) a °>( x°−a °); and x°/ 2> a°.