Permanent magnet type stepping motor

Claim 2

A permanent magnet type stepping motor comprising: a stator having a plurality of radially-extended magnetic poles provided on its inner periphery, each of said plurality of magnetic poles being provided at its tip end with a plurality of pole teeth arranged as equally spaced by an identical pitch, said stator also having a plurality of windings wound around the plurality of corresponding magnetic poles, any of the two magnetic poles angularly shifted by 180 degrees having the same polarity; a rotor having two rotor magnetic poles disposed to be concentric with said stator as spaced by a gap from inside the stator and also provided on their full circumferential peripheries with a plurality of pole teeth shifted by 1/2 pitch from each other and an axially-magnetized permanent magnet held between said rotor magnetic poles: wherein the magnetic poles of said stator are set at 6 in number as arranged equally with an identical pitch, the pitch τ S of the pole teeth provided at the tip ends of the respective magnetic poles of the stator is set to be equal to the pitch τ R of the pole teeth of the rotor, an angle θ r made between one of the pole teeth of the stator magnetic poles and one of the pole teeth of the rotor magnetic poles opposing thereto is set to satisfy a relationship θ r =120°/Z, said pole tooth number Z of the rotor magnetic poles is set to satisfy a relationship Z=6n±4 (where n is a positive integer), and said motor is driven with one of 3, 6, 7 and 9 lead wires.

Claim 3

A permanent magnet type stepping motor comprising: a stator having a plurality of radially-extended magnetic poles provided on its inner periphery, each of said plurality of magnetic poles being provided at its tip end with a plurality of pole teeth arranged as equally spaced by an identical pitch, said stator also having a plurality of windings wound around the plurality of corresponding magnetic poles, any of the two magnetic poles angularly shifted by 180 degrees having the same polarity; a rotor having two rotor magnetic poles disposed to be concentric with said stator as spaced by a gap from inside the stator and also provided on their full cirumferential peripheries with a plurality of pole teeth shifted by 1/2 pitch from each other and an axially-magnetized permanent magnet held between said rotor magnetic poles; wherein the magnetic poles of said stator are set at 6 in number as arranged equally with an identical pitch, the pitch τ S of the pole teeth of said stator magnetic poles and the pitch τ R of the pole teeth of said rotor magnetic poles satisfy correlations of τ S =180° τ R /(180°±τ R ) and 60/τ S =m (where m is 1,2, . . . ), an angle θ r made between one of the pole teeth of the stator magnetic poles and one of the pole teeth of the rotor magnetic poles opposing thereto is set to satisfy a relationship θ r =120°/Z, said pole tooth number Z of the rotor magnetic poles is set to satisfy a relationship Z=6n±4 (where n is a positive integer), and said motor is driven with one of 3, 6, 7 and 9 lead wires.

Claim 4

A permanent magnet type stepping motor comprising: a stator having a plurality of radially-extended magnetic poles provided on its inner periphery, each of said plurality of magnetic poles being provided at its tip end with a plurality of pole teeth arranged as equally spaced by an identical pitch, said stator also having a plurality of windings wound around the plurality of corresponding magnetic poles, any of the two magnetic poles angularly shifted by 180 degrees having the same polarity; a rotor having two rotor magnetic poles disposed to be concentric with said stator as spaced by a gap from inside the stator and also provided on their full cirumferential peripheries with a plurality of pole teeth shifted by 1/2 pitch from each other and an axially-magnetized permanent magnet held between said rotor magnetic poles; wherein the magnetic poles of said stator are set at 6 in number as arranged equally with an identical pitch, the pitch τ S of the pole teeth of said stator magnetic poles and the pitch τ R of the pole teeth of said rotor magnetic poles satisfy correlations of τ S =180° τ R /(180°±τ R ) and 60/τ S =m (where m is 1,2, . . . ), an angle θ r made between one of the pole teeth of the stator magnetic poles and one of the pole teeth of the rotor magnetic poles opposing thereto is set to satisfy a relationship θ r =120°/Z, said pole tooth number Z of the rotor magnetic poles is set to satisfy a relationship Z=6n±4 (where n is a positive integer), and said motor is driven with one of 3, 6, 7 and 9 lead wires.