Method and system for open lamp protection
AssigneeMonolithic Power Systems, Inc.
InventorsYuancheng Ren, Kaiwei Yao, Wei Chen
Life of this patent
Estimating the term…
Abstract
A detector circuit monitors the phase relationship between the lamp voltage and the excitation voltage, and if one or more conditions are met, triggers the open lamp protection process in a discharge lamp system. The detection circuit can be incorporated into a lamp voltage feedback circuit and implemented on the integrated circuit level with less cost and circuit complexity.
Claims15
1-10. (canceled)
A method for detecting an open lamp condition in a discharge lamp system, comprising:
- monitoring the phase relationship between the lamp voltage of at least one discharge lamp and the gate voltage of at least one power device through a detector circuit;
- deriving a voltage signal from said detector circuit;
- and
- if said voltage signal satisfies an open lamp condition, triggering an open lamp protection process.
A circuit capable of detecting an open lamp condition, and triggering an open lamp protection process in a discharge lamp system, comprising:
- a sensing capacitor being coupled to a discharge lamp;
- a differential circuit with its input terminal being coupled to said sensing capacitor;
- a comparator with its negative terminal being coupled to the output terminal of said differential circuit and its positive terminal being coupled to ground or a threshold voltage;
- and
- an AND gate with one input terminal being coupled to the output terminal of said comparator and the other input terminal being coupled to a pulse signal representing the middle portion of the excitation voltage.
A circuit for detecting an open lamp condition in a discharge lamp system, comprising:
- means for monitoring the phase relationship between the lamp voltage of at least one discharge lamp and the gate voltage of at least one power device through a detector circuit;
- means for deriving a voltage signal from said detector circuit;
- and
- logic means operative such that if said voltage signal satisfies an open lamp condition, triggering an open lamp protection process.
Dependencies are inferred from the claim text.