With the emergence of the electric or electronic watch having a balance wheel as its main or central timekeeping element actuated by a drive coil mounted thereon, an inexpensive and reliable arrangement is needed to electrically connect the oscillating drive coil to the electric watch drive and/or synchronizing circuitry.
A known arrangement to connect the drive coil to the electric watch drive circuitry is described in German Pat. No. 1,078,677 issued Sept. 22, 1960 to Ewald Zemla. In this arrangement, the hairspring consists of three flat layers, i.e. two electrically conductive strips with an insulation strip therebetween. The hub consists of an insulating bushing, which is slipped onto the balance wheel arbor or staff, and two metallic ring halves surrounding the insulating bushing. The ring halves form a slot to receive one end of the hairspring, whereby its conductor strips are each connected to a ring half of the hub. Although a round or oval type of hairspring is shown, no arrangement is shown or suggested for fastening the hairspring to the hub. The obvious disadvantages of this known arrangement are that it requires a complicated and expensive hub construction and that great care must be taken when fastening the hairspring in the hub so that the conductor strips do not suffer damage.
The prior art also includes U.S. Patent No. 3,332,229 issued July 25, 1967 to Klinck and U.S. Pat. No. 3,553,956 issued Jan. 12, 1971 to Schwartz, Wurmberg and Weise. The above mentioned patents are mentioned as being representative of the prior art only and other pertinent patents may exist. None of the above cited patents are deemed to effect the patentability of the present invention.
It is an objective of the present invention to provide a two conductor hairspring and hub arrangement, which arrangement or device will be relatively low in cost and will utilize relatively few parts.
Further advantages and objectives of the present invention will be apparent from the following detailed description of the preferred embodiments of the invention.