Claw-pole stepping motor with rotor including vibration reducing magnet

A claw-pole stepping motor, comprising:

• a base formed of soft magnetic material;
• a stator assembly of stacked plural stators supported by the base, said plural stators being individually excited;
• a bearing connected to the base and being concentrically disposed with the stator assembly;
• a rotor assembly rotatably supported on the bearing, above the base, via a shaft, and having
• (a) field magnets thereon opposed to the stator assembly,
• (b) a magnetized portion, which is an index generating magnet positioned radially inside and integral with the field magnets of the rotor, said magnetized portion having a magnetic strength less than a magnetic strength of the field magnets, to be attracted to the base below the rotor assembly, and thereby reduce vibrations in the motor, and
• (c) a shield ring having a back yoke positioned between the field magnets and the magnetized portion serving as a back yoke of the field magnets and preventing flux from leaking from the stator to the shaft;
• and
• a shield plate covering the stator assembly and the field magnets of the rotor assembly wherein said field magnets and said magnetized portion are intrgrally molded together as a single plastic magnet.

A claw-pole stepping motor, comprising:

• a base formed of soft magnetic material;
• a stator assembly of stacked plural stators supported by the base, said plural stators being individually excited;
• a bearing connected to the base and being concentrically disposed with the stator assembly;
• a rotor assembly rotatably supported on the bearing, above the base, via a shaft, and having
• (a) field magnets thereon opposed to the stator assembly,
• (b) a magnetized portion, which is an index generating magnet positioned radially inside and integral with the field magnets of the rotor, said magnetized portion having a magnetic strength less than a magnetic strength of the field magnets, to be attracted to the base below the rotor assembly, and thereby reduce vibrations in the motor, and
• (c) a shield ring having a back yoke positioned between the field magnets and the magnetized portion serving as a back voke of the field magnets and preventing flux from leaking from the stator to the shaft;
• and
• a shield plate covering the stator assembly and the field magnets of the rotor assembly.
• wherein said field magnets and said magnetized portion are integrally molded as a single plastic magnet, and
• wherein said shield ring is fixed to the field magnets and the index generating magnet by plastic molding.

A claw-pole stepping motor, comprising:

• a base formed of soft magnetic material;
• a stator assembly of stacked plural stators supported by the base, said plural stators being individually excited;
• a bearing connected to the base and being concentrically disposed with the stator assembly;
• a rotor assembly rotatably supported on the bearing, above the base, via a shaft, and having
• (a) field magnets thereon opposed to the stator assembly,
• (b) a first magnetized portion positioned radially inside and integral with the field magnets, said first magnetized portion having a magnetic strength less than a magnetic strength of the field magnets, to be attracted to the base below the rotor assembly, and thereby reduce vibrations in the motor, and
• (c) a second magnetized portion above the first magnetized portion for attracting a magnetic recording disk,
• (d) a shield ring having a back yoke positioned between the field magnets and the first magnetized portion serving as a back yoke of the field magnets and preventing flux from leaking from the stator to the shaft;
• and
• a shield plate covering the stator assembly and the field magnets of the rotor assembly,
• wherein said first magnetized portion is an index generating magnet wherein said field magnets and said magnetized portion are intrgrally molded together as a single plastic magnet.

A claw-pole stepping motor, comprising:

• a base formed of soft magnetic material;
• a stator assembly of stacked plural stators supported by the base, said plural stators being individually excited;
• a bearing connected to the base and being concentrically disposed with the stator assembly;
• a rotor assembly rotatable supported on the bearing, above the base, via a shaft, and having
• (a) field magnets thereon opposed to the stator assembly,
• (b) a first magnetized portion positioned radially inside and integral with the field magnets, said first magnetized portion being an index generating magnet and having a magnetic strength less than a magnetic strength of the field magnets, to be attracted to the base below the rotor assembly, and thereby reduce vibrations in the motor,
• (c) a second magnetized portion above the first magnetized portion for attracting a magnetic recording disk, and
• (d) a shield ring having a back yoke positioned between the field magnets and the first magnetized portion serving as a back yoke of the field magnets and preventing flux from leaking from the stator to the shaft;
• and
• a shield plate covering the stator assembly and the field magnets of the rotor assembly,
• wherein said field magnets and said first and second magnetized portions are integrally molded as a single plastic magnet.