A horological instrument includes an oscillator such as a balance wheel. The oscillator carries a coil, which may consist of a single conductive ring. Current is induced in the moving coil by mutual induction from a fixed coil. One or more fixed magnetic fields are positioned to drive the energized coil. A circuit is provided to energize the coil with current at the proper moment during its oscillation. DESCRIPTION The present invention relates to horology and more particularly to a horological instrument utilizing an electronic circuit. The improvement in battery construction and capability in recent years has provided renewed interest in horological instruments having a self-contained source of power. A clock may now be manufactured having a battery within its case, thereby avoiding the necessity of connecting the clock to an electrical outlet. Similarly, a watch may now be manufactured in which a small button type of primary battery cell is contained within the watch case and provides the power to operate the watch movement. Various approaches have been taken by manufacturers of horological movements in applying the timekeeping ability of an oscillator to an electronic horological instrument. For example, watches have been manufactured in which one or more magnets have been mounted on a balance wheel, which carried the magnets through the fields of one or more coils. Such movements have either utilized a make-break contact carried by the balance wheel or a separate pick-up coil which triggers an electronic circuit. In another type of watch movement the balance wheel carries a coil which moves through the field of a number of permanent magnets which are fixed to the watch plate. The coil receives current either through a make-break contact or by means of two hairsprings. Various other systems have been proposed. However, generally they require that the oscillator, for example, the balance wheel or tuning fork, carry either a coil or a magnet. When the oscillator carries a magnet there are problems presented in regard to the magnetic fields temporarily established in the path of oscillation by the moving magnet. The moving magnet type of horological instrument may be sensitive to external magnetic influence or external demagnetizing forces. In those horological instruments in which the oscillator carries an electric coil, it is necessary that current reach the coil. The means by which the current is carried to the moving coil, for example, the use of two hairsprings or make-break contacts, may present difficulties in regard to the expense of the movement. It is necessary to electrically isolate the coil, hairspring and contacts from other portions of the balance wheel and such electrical isolation may be accomplished using plastic materials. However, such plastic materials may be sensitive to humidity, so that their weight increases in a humid atmosphere, causing the balance wheel to become less perfectly balanced. It is the objective of the present invention to provide a horological instrument utilizing an oscillator as its time base in which the oscillator is not sensitive to changes in humidity; in which the oscillator assembly is relatively simple and inexpensive; and in which the oscillator does not present difficulties in magnetic shielding. In accordance with the present invention, a horological instrument is provided in which the oscillator carries a coil. The coil may be a single blanked turn of copper or other conductive non-magnetic material. An electric current is induced into the coil carried by the oscillator by means of a coil fixed to the movement. The induced current in the moving coil reacts with a permanent magnet or a magnetic field of a second coil, the permanent magnet or second coil being fixed to the movement. The oscillator, which may be a balance wheel, need be connected to the movement frame and bridge only by its pivoting and spring mechanisms, for example, in the case of a balance wheel, the balance wheel staff and its conventional hairspring. The coil carried by the oscillator does not carry with it any magnetic field past its operating position. Consequently, the coil carried by the oscillator will not have any adverse magnetic effects on the movement and cannot be demagnetized by external magnetic forces. A circuit is provided which enables the watch movement to be self-starting. The circuit is a self-oscillating circuit whose frequency is determined by the movement of the physical oscillator but which, in addition, has a self-oscillating frequency of its own for the purpose of starting the motion of the physical oscillator. The circuit is triggered or synchronized by the movement of the physical oscillator. It is possible, due to the arrangement of the coils, to provide that the indexing of the index wheel of the movement occurs from one of the coils fixed to the plate rather than from, as in other watches, the moving oscillator. This enables the physical oscillator to be relatively free-moving and undamped.
