Abstract: An intra-osseous support structure can be used to fixate opposed portions of bone. In some examples, the intra-osseous support structure is positioned in openings formed in adjacent portions of bones. Fasteners are inserted through the bone portions to secure the intra-osseous support structure in the bones. Depending on the application, one or more external bone plates may also be applied to the bone portions. The external bone plate may be in compression while the intra-osseous support structure is in tension under load in situ.

Abstract: A method of and apparatus for operating a high intensity gas discharge lamp is provided wherein the inverter circuit operates at a controlled frequency such that deleterious effects of the lamp's acoustic resonant frequencies are minimized. The inverter utilizes a transformer output with high leakage inductance. The high leakage inductance provides low loss switching operation and simplified control of lamp current during both ignition and warm-up. High frequency operation as well as judicious component design and specification reduces component count, assembled size and cost of ballast.

Abstract: A single power transistor oscillator circuit includes a single transistor oscillator coupled by an inductive means including an inductive coil and transformer to a DC potential development means with a wave-shaping means coupled to a secondary winding of the transformer to provide a substantially symmetrical AC potential centered about a zero level DC voltage and applied to a load circuit.

Abstract: The above and other objects, advantages and capabilities are achieved in one aspect of the invention by an output circuit for an electronic ballast system. The circuit includes N sets of output connections for accepting N lamps. The lamps are driven by an output autotransformer coupled to the lamps through a feedback winding that is used to apply a feedback signal to an inverter drive circuit. Capacitive impedances are coupled across the lamps so that the capacitances, the lamp filaments, the feedback winding, and the output transformer form a circuit loop. The capacitances are chosen to have an impedance, at the inverter operating frequency, less than the pre-ignition impedance of the lamps and greater than the post-ignition impedance.

Abstract: The above and other objects, advantages and capabilities are achieved in one aspect of this invention by a drive scheme for a plurality, that is, for N, where N-2, flourescent lamps. The drive circuit comprises (N+1) pairs of output terminals, each comprising associated first and second individual terminals. An output transformer is coupled at one end to the (0,1).sup.1 terminal and at another end to the (0,1).sup.N+1 terminal. N impedance elements, typically capacitors, are coupled across associated pairs of lamp filaments in a fashion whereby each impedance element is coupled at one end to the second terminal of one pair and at another end to the second terminal of the succeeding pair. To wit: The first impedance element is coupled between the second terminal of the first pair, and the N.sup.th element is coupled between the second terminal of the N.sup.th pair and the second terminal of the (N+1).sup.th pair.

Abstract: A stabilized dimming circuit for an electronic ballast system. The dimming circuit includes a transformer having a variable inductance primary included as a part of a feedback loop comprising a push-pull inverter and an output transformer for supplying a drive signal to a lamp filament. As the inductance of the primary is varied (decreased), the amount of feedback applied to the inverter is varied (increased) and the lamp brightness dimmed accordingly. The secondary of the dimming transformer is included in a loop that is completed by a secondary winding of the output transformer and a lamp filament. Because the voltage induced in the secondary of the dimming transformer is held relatively constant, the voltage applied to the filament is stabilized in spite of varations in the amount of power supplied to the lamp.

Abstract: In order to effect stabilized dimming of a fluorescent lamp, that is, in order to vary the power level supplied the lamp while maintaining a substantially constant filament voltage, a first, variable, inductance is included as an element of oscillator (inverter) feedback loop. The voltage across the variable inductance is clamped and coupled to a second inductance so that a voltage appears across the second inductance in proportion to the voltage appearing across the variable inductance. The voltage appearing across the second inductance is applied to the lamp filament so as to constitute a dominant component of the lamp filament voltage.

Abstract: An output configuration for an electronic ballast system includes means for effecting independent selection of both pre- and post-ignition lamp filament voltages. The primary of a filament voltage control transformer is coupled to lamp filaments so as to induce a voltage in the transformer secondary windings in relation to the lamp filament current. The secondary windings are arranged so that the voltage induced therein adds to the voltage provided to the lamp filaments by filament drive windings on the ballast output transformer.

Abstract: A delayed starting circuit for an electronic ballast system that includes an inverter coupled to a secondary voltage source. The starting circuit includes a voltage divider having an input coupled to a charge storage capacitance in the voltage source and an output coupled through a semiconductor switching device to an input of the inverter. The switching device remains non-conductive until the capacitance has been substantially charged, thereby protecting the inverter from transients encountered as a surge of charge is delivered to the capacitance subsequent to the initial energization of the ballast circuit.

Abstract: An improved output configuration for a multiple-lamp electronic ballast system. The output includes a differential transformer having a primary adapted to be coupled in a first loop including a first filament filament drive winding and feedback winding and a secondary adapted to be coupled in a second loop that includes a second filament, filament drive winding and feedback winding.The improvement allows the entire ballast to be shut down when a lamp has been removed thereby avoiding aberrant oscillator operation under abnormal, yet predictable, lamp load conditions.

Abstract: An improved drive scheme for a pair of push-pull inverter transistors in an electronic ballast circuit. The inverter output is coupled through a series resonant circuit comprising a capacitor and the primary winding of an output transformer. The resonant circuit is coupled to the inverter output through an additional winding on the primary of an interstage so that a component of the loop current is fed back to the bases of the push-pull transistors, thereby compensating for phase errors in the drive signal applied at the inverter input.