Claims
- 1. A The two-pole step motor for a timepiece comprising:a rotor including a rotor magnet and a rotor axle; a stator comprising a high-permeability material, having a rotor hole in which the rotor is installed; and a field coil for excitation, including a magnetic core comprising a high-permeability material around which a conductor is wound, and opposite ends of which are magnetically bonded to opposite ends of the stator; wherein the stator comprises a plurality of holding torque setting means disposed on inner periphery of the rotor hole at installation angles differing in a direction of the inner periphery; and wherein at least one of the plurality of the holding torque setting means is formed in shape asymmetrical with respect to a center of the rotor hole, wherein said holding torque setting means formed in a shape asymmetrical with respect to the center of the rotor hole comprises a pair of recesses facing each other, formed on the inner periphery of the rotor hole, on opposite sides of the center of the rotor hole.
- 2. A The two-pole step motor for a timepiece comprising:a rotor including a rotor magnet and a rotor axle; a stator comprising a high-permeability material, having a rotor hole in which the rotor is installed; and a field coil for excitation including a magnetic core comprising a high-permeability material around which a conductor is wound, and opposite ends of which are magnetically bonded to opposite ends of the stator; wherein the stator comprises a plurality of holding torque setting means disposed on inner periphery of the rotor hole at installation angles differing in a direction of the inner periphery; and wherein at least one of the plurality of the holding torque setting means is formed in share asymmetrical with respect to a center of the rotor hole, wherein said holding torque setting means formed in a shape asymmetrical with respect to the center of the rotor hole comprises a pair of protuberances facing each other, formed on the inner periphery of the rotor hole, on opposite sides of the center of the rotor hole.
- 3. The two-pole step motor for a timepiece according to claim 2, wherein said pair of recesses are differentiated from each other in at least one of width and depth.
- 4. The two-pole step motor for a timepiece according to claim 2, wherein said pair of protuberances are differentiated from each other in at least one of width and depth.
- 5. The two-pole step motor for a timepiece according to claim 1, wherein said stator is made up by bonding a first stator part made of a high-permeability material and a second stator part made of a high-permeability material through an intermediary of two connections made of a low-permeability material or a nonmagnetic material, andthe connections serve as said holding torque setting means, except one formed in the shape asymmetrical with respect to the center of the rotor hole.
- 6. The two-pole step motor for a timepiece according to claim 2, wherein said stator is made up by bonding a first stator part made of a high-permeability material and a second stator part made of a high-permeability material through an intermediary of two connections made of a low-permeability material or a nonmagnetic material, and the connections serve as said holding torque setting means, except one formed in the shape asymmetrical with respect to the center of the rotor hole.
Priority Claims (3)
Number |
Date |
Country |
Kind |
10-163682 |
Jun 1998 |
JP |
|
10-307961 |
Oct 1998 |
JP |
|
11-49386 |
Feb 1999 |
JP |
|
Parent Case Info
This application is a division of Ser. No. 09/719,369 filed Dec. 11, 2000 now U.S. Pat. No. 6,548,922 which is a 371 of PCT/JP99/03109 filed Jun. 10, 1999.
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