| 摘要 |
1,103,283. Clocks and watches. TOKEI KABUSHIKI KAISHA. Feb. 22, 1966 [Feb. 22, 1965; March 1, 1965; March 31, 1965], No.7661/66. Heading G3T. A timepiece balance wheel loaded by a hair spring 2 comprises a pair of plates 3, 4 made of a magnetically permeable material on which are fixed magnets 7, 8 and 9, 10, a stationary search and drive-coil assembly 11 and a transistor circuit, which amplifies pulses induced in the search coil and feeds them to the drive-coil to maintain the oscillation of the balance wheel. Each plate 3, 4, which is fixed to the balance wheel shaft 1, has weights 5, 6 to counterbalance the magnets. By making the plates 3, 4 of pure iron, steel, Permendur (Registered Trade Mark) &c., flux paths are formed around the peripheries of the plates and stray flux from the magnets is reduced to a minimum. The edges of the plates 3, 4 may be inwardly turned to strengthen the plates and further reduce stray flux. The coil assembly 11 is wound on a ring core and covered by layers of polyester, nylon &c. The oscillation of the balance wheel is maintained by a transistor circuit which incorporates a fixed biasing resistor (R) and a variable resistor (VR) for adjusting the oscillation amplitude. A self-oscillation suppressing condenser may be connected between the transistor collector and base and the fixed circuit elements are embedded in a block of insulating synthetic resin such as polypropylene &c. A roller is attached to the lower end of the balance wheel shaft 1 and co-operates with a conventional lever escapement. Reference has been directed by the Comptroller to Specification 746,465.
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