Claims
- 1. In an electronic wristwatch including a step motor for receiving timekeeping signals and converting same into an incremental rotary motion, the improvement comprising a permanent magnet rotor, a magnetic permeable stator surrounding said rotor for incrementally rotating said rotor in response to changes in the magnetic orientation of said stator, and coil means including an elongated magnetic permeable coil core and a coil wrapped therearound, said coil being adapted to receive timekeeping signals and in response thereto change the magnetic orientation of said stator, and magnetic shield means extending the lengthwise extent of the coil, said shield means including a shield plate having an opening therein for permitting said coil to be disposed in the opening of said plate to thereby surround said coil and having minimum cross-sectional area transverse to the lengthwise extent of said magnetic permeable core, the ratio of said minimum cross-sectional area of the shielding plate in a direction transverse to the lengthwise extent of the coil core to the minimum cross-sectional area of the coil core taken transverse to the lengthwise extent of the coil core, is at least one and no greater than five to thereby provide a reduced dimensional shielding plate and hence a reduction in the thickness of the timepiece.
- 2. An electronic wristwatch as claimed in claim 1, wherein said magnetic shielding means is a magnetic permeable plate secured to said step motor by fastening screw means.
- 3. An electronic wristwatch as claimed in claim 2, wherein said plate is adapted to be releaseably secured to said step motor by removal of said fastening screw means.
- 4. An electronic wristwatch as claimed in claim 1, wherein said shielding plate is releasably secured to said coil core and said step motor by said screw means.
- 5. An electronic wristwatch as claimed in claim 1, wherein the magnetic permeability of said coil core and said magnetic shielding plate is larger than the magnetic permeability of said stator.
- 6. An electronic wristwatch as claimed in claim 1, and including a base plate, said magnetic permeable stator, said permanent magnet rotor and said coil being supported on said base plate, said base plate having an opening therein, at least a portion of said coil being disposed in said opening in said base plate.
- 7. An electronic wristwatch as claimed in claim 1, wherein said shield plate, said rotor and said stator are each positioned so that imaginary planes that pass therethrough are parallel to each other and pass through at least one of said coil and coil core.
Priority Claims (1)
Number |
Date |
Country |
Kind |
52-16486 |
Feb 1977 |
JPX |
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Parent Case Info
This is a continuation of application Ser. No. 878,836, filed Feb. 17, 1978, now abandoned.
US Referenced Citations (7)
Foreign Referenced Citations (1)
Number |
Date |
Country |
2640817 |
Mar 1977 |
DEX |
Continuations (1)
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Number |
Date |
Country |
Parent |
878836 |
Feb 1978 |
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