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AssigneeFulham Company Limited
InventorsNing Zhai, Xingwei Hu
Estimating the term…
A technique for providing control for an electronic ballast by responding to the current in the common bus (DC power rail) between a boost circuit such as a power factor circuit (PFC) and an output (such as a high frequency (HF) inverter) circuit, and adjusting, changing or shutting down either the power factor control circuit or the inverter circuit when the power going into the inverter circuit is above a threshold. Power going into the inverter circuit may be measured by a resistor, and temperature compensation may be provided. Excess power indicative of a spark is detected in such a way that normal starting of a lamp load connected to the ballast occurs without triggering the change/shutdown but an external arc will trigger the change/shutdown. For example, the output circuit may be shut down and the external arc curtailed within 200 msecs.
A ballast circuit comprising an input circuit, a boost circuit coupled to the input circuit, an inverter circuit having an input and an output for driving a load, and a sensing circuit coupled to the inverter circuit input through a control circuit and wherein the sensing circuit includes an output coupled through the control circuit by way of a high impedance input node of the control circuit and to the boost circuit for changing the boost circuit when an electrical signal on the input to the inverter circuit changes a selected amount.
A ballast circuit comprising an AC input, an inverter circuit having an input for receiving an electric current and having an output circuit configured to be coupled to a load, a boost circuit between the AC input and the inverter circuit, and a sensing circuit for sensing a characteristic of the electric current received at the input of the inverter circuit and configured to apply a control signal to the boost circuit through a high impedance input node of a control circuit when the characteristic of the electric current received at the input of the inverter circuit becomes a predetermined characteristic.
A ballast circuit comprising an input circuit, a boost circuit coupled to the input circuit, an inverter circuit having an input and an output for driving a load, a boost circuit controller having a high impedance input, and a sensing circuit coupled to the inverter circuit input and having an output coupled to the high impedance input wherein the sensing circuit applies a signal to the boost circuit controller high impedance input when a signal on the input to the inverter circuit changes a selected amount.
Dependencies are inferred from the claim text.