Synchronous motor device for timepiece

• US 4,565,955 A
• Filed: 10/21/1983
• Issued: 01/21/1986
• Est. Priority Date: 10/29/1982
• Status: Expired due to Fees

• Current Assignee: Rhythm Watch Company Limited (Rhythm Co., Ltd.)
• Original Assignee: Rhythm Watch Company Limited (Rhythm Co., Ltd.)
• Inventors: Kubota, Susumu
• Primary Examiner(s): Smith, Jr., David
• Application Number:
  US06/544,395
• Time in Patent Office: 823 Days
• Field of Search: 310/162, 310/49 R, 310/40 MM, 318/696, 318/254, 318/138, 368/157
• US Class Current: 318/696
• CPC Class Codes: G04C 15/00 Clocks driven by synchronous motors
• CPC Class Codes: G04C 3/16 incorporating an electro-dynamic continuously rotating motor G04C3/02 - G04C3/12 take precedence; clocks driven by synchronous motors G04C15/00; apparatus which can be set and started to measure-off predetermined or adjustably-fixed time intervals with electric driving means, e.g. incorporating clocks G04F3/06, G04F3/08; electromechanical stop watches G04F8/00
• CPC Class Codes: H02K 21/185 with the axis of the rotor perpendicular to the plane of the armature
• CPC Class Codes: H02K 37/16 having horseshoe armature cores
• CPC Class Codes: H02P 1/46 for starting an individual synchronous motor H02P27/04 takes precedence

Abstract

A synchronous motor device for a timepiece including a synchronous motor for the timepiece having a rotor with a pair of magnetized rotor poles around its circumference, a stator consisting of a pair of stator plates with a plurality of stator poles arranged around the vicinity of said rotor separated by an air gap, and an energizing coil supplying alternating magnetic flux to said stator.

The synchronous motor for timepiece includes main stator poles, first supplementary stator poles and second supplementary stator poles.

The main stator poles are further provided with both of the stator plates at the facing position against the rotor shaft and mainly forms the static stable position of the rotor. The first supplementary stator poles are facingly positioned against the rotor shaft and provided with both of the stator plates at separate positions from said main stator poles. This first supplmentary stator poles form the dynamic stable position of the rotor in the cooperation with the main stator poles and have wider gaps than the main stator poles. The second supplementary stator poles are facingly positioned against the rotor shaft and provided in the vicinity of the dynamic stable position of the rotor in order to place the predetermined braking force on the rotor which rotates over the dynamic stable position. This second supplementary stator poles have wider air gaps than the main stator poles and the first supplementary stator poles. Consequently the synchronous motor can achieve the properties of smooth self-starting rotation.

Claims

1. A synchronous motor device for timepiece including a synchronous motor for timepiece having:

a rotor having a pair of magnetized rotor poles around its circumference;

a stator consisting of a pair of stator plates having a plurality of stator poles arranged around the vicinity of said rotor with separation of air gap; and

an energizing coil supplying alternating magnetic flux to said stator;

wherein said synchronous motor for timepiece comprises;

main stator poles being prepared with both of the stator poles at the facing position against the rotor shaft and mainly forming a static stable position of the rotor;

first supplementary stator poles being facingly positioned against the rotor shaft, being prepared with both of the stator poles at separate position from said main stator poles, forming a dynamic stable position of the rotor with the cooperation of said main stator poles, and having wider airgaps than said main stator poles; and

second supplementary stator poles being facingly positioned against the rotor shaft, being prepared in the vicinity of the dynamic stable position of the rotor in order to place a predetermined braking force on the rotor which rotates over the dynamic stable position, having wider air gaps than said main stator poles and said first supplementary stator poles;

whereby smooth self-starting rotation can be achieved.

2. Asynchronous motor device for timepiece according to claim 1, wherein said main stator poles consist of divided poles.

3. A synchronous motor device for timepiece according to claim 1, wherein said first supplementary stator poles consist of divided poles.

4. A synchronous motor device for timepiece including a synchronous motor for timepiece having:

a rotor having a pair of magnetized rotor poles around its circumference;

a stator consisting of a pair of stator plates having a plurality of stator poles arranged around the vicinity of said rotor with separation of air gap; and

an energizing coil supplying alternating magnetic flux to said stator;

wherein said synchronous motor for timepiece comprises;

main stator poles being prepared with both of the stator poles at the facing position against the rotor shaft and mainly forming static stable position of the rotor;

first supplementary stator poles being facingly positioned against the rotor shaft, being prepared with both of the stator poles at the separate position from said main stator poles, forming the dynamic stable position of the rotor with the cooperation of said main stator poles, and having wider air gaps than said main stator poles; and

second supplementary stator poles being facingly positioned against the rotor shaft, being prepared in the vicinity of the dynamic stable position of the rotor in order to place predetermined braking force on the rotor which rotates over the dynamic stable position, having wider air gaps than said main stator poles and said first supplementary stator poles; and

further

said synchronous motor device for timepiece comprises;

a detector detecting the time of said synchronous motor for timepiece starting its rotation, and since then for certain period driving said synchronous motor for timepiece at constand speed rotation with the drive pulses of wider pulse width than normal pulse width, and further gradually decreasing at steps the pulse width of the drive pulses generated within a certain period after said motor'"'"'s starting its rotation into the pulse width of the normal drive pulses within the region of not exceeding 20 percent of the widest pulse width among the supplied drive pulses.

5. A synchronous motor device for timepiece according to claim 4, wherein said detector detects the switch-on time of power source of battery.