Ballast with lamp sensor and method therefor
AssigneeQ Technology, Inc.
InventorTom Stack
Life of this patent
Estimating the term…
Abstract
A ballast circuit is provided having an input, an output for coupling to an electric discharge lamp and an oscillation circuit for illuminating the lamp. A circuit may be included for sensing when a voltage on an input to the oscillation circuit exceeds desired levels. The ballast circuit may be shut down, limited or otherwise controlled to reduce the possibility of ballast failure.
Claims39
A15. The ballast circuit of claim 1 wherein the shut-off device includes a component selected from the group of a silicon control rectifier, a bi-polar transistor, an opto-isolator and a MOSFET.
A ballast circuit comprising:
- a DC input circuit having a high voltage line and a base line;
- a lamp drive circuit coupled between the high voltage line and the base line;
- an output circuit coupled to the lamp drive circuit for producing a lamp drive current used for driving an electric discharge lamp;
- and
- a ballast protection circuit for protecting the lamp drive circuit, comprising:
- a detection circuit coupled between the high voltage line and the base line configured to detect when a voltage on the high voltage line exceeds a threshold, and
- a shutoff device coupled to the detection circuit and to the lamp drive circuit for preventing the lamp drive circuit from producing a lamp drive current when the voltage on the high voltage line exceeds the threshold.
A method of protecting a ballast circuit having an inverter from generating a lamp drive current that is excessive, comprising:
- sensing an input voltage that varies as a function of an input to the ballast;
- and
- preventing the inverter from generating the lamp drive current if the voltage exceeds a predetermined voltage by preventing a transistor in the inverter from conducting current.
A ballast circuit comprising:
- an input circuit for receiving current from a current source;
- an output circuit for supplying power to an electric discharge lamp;
- and
- a ballast protection circuit between the input and the output circuits for protecting the ballast circuit from providing excessive power at the output circuit, the protection circuit including a voltage sensing circuit for sensing a voltage in the input circuit and a response circuit coupled to the voltage sensing circuit for reducing the power provided by the output circuit when the voltage reaches a given level.
A ballast circuit comprising:
- an input circuit for receiving power from a power source;
- an output circuit for supplying drive current to an electric discharge lamp;
- an oscillation circuit between the input and the output for creating an oscillating current for the output circuit to drive the electric discharge lamp;
- and
- a ballast protection circuit coupled to the input circuit for protecting the ballast circuit from excessive drive current being developed in the output circuit, the protection circuit including at least one diode and a trigger circuit coupled to the at least one diode for reducing the drive current in the output circuit when a voltage in the input circuit reaches a given level.
A ballast circuit comprising:
- a DC input circuit;
- a lamp drive circuit coupled the DC input circuit;
- an output circuit from the lamp drive circuit for producing a lamp drive current used for driving an electric discharge lamp;
- and
- a ballast protection circuit for protecting the lamp drive circuit, including a detection circuit coupled to the DC input circuit and configured to detect when a voltage from the DC input circuit exceeds a threshold, and a shutoff device coupled to the detection circuit and to the lamp drive circuit for preventing the lamp drive circuit from producing a lamp drive current.
Dependencies are inferred from the claim text.