Patent ID: 7825556

Claim:
A stepping motor comprising: a stator comprising a first yoke having a cup-like configuration comprising a hollow cylinder wall and a bottom plate to cover one end of the hollow cylinder wall, the bottom plate having (1) a circular opening formed at its center, (2) a first plurality of pole teeth formed along a circumference of the circular opening and extending axially parallel to the hollow cylinder wall, and (3) a plurality of notches formed to extend radially outwardly from the circumference of the circular opening, each of the notches being located between two adjacent pole teeth, a second yoke having a second plurality of pole teeth disposed to intermesh with the first plurality of pole teeth of the first yoke on a same circumferential plane, the second yoke, together with the first yoke, forming an annular hollow space, a coil, and a bobbin having the coil wound therearound and being housed in the annular hollow space formed by the first and second yokes; a rotor rotatably disposed in a cylindrical hollow space enclosed by the first and second pluralities of pole teeth of the stator, the rotor comprising a shaft, and a magnet fixed on the shaft; and a pair of bearings disposed to sandwich the magnet of the rotor, each of the bearings attached to the first yoke of the stator, wherein the bearing comprises a hollow-cylindrical main body, and a flange structure comprising a plurality of protrusions to extend radially outwardly, to engage with the plurality of notches of the bottom plate of the first yoke, and to be disposed in contact with the bobbin, and wherein the circular opening is further defined by inner faces of the first plurality of pole teeth of the first yoke, and the hollow-cylindrical main body is fitted inside the further defined circular opening.