Lamp out detection for miniature cold cathode fluorescent lamp system
First Claim
1. A circuit for supplying power to a fluorescent lamp comprising:
- a. controller circuit;
b. a buck regulator for forming a buck current signal wherein the buck regulator is coupled to be controlled by the controller circuit;
c. an inverter for forming a lamp signal, the inverter having an input node, wherein the input node is coupled to receive the buck current signal;
d. a sensing circuit for forming a sensing signal representative of a voltage at the input node; and
e. means for deactivating the controller circuit if the sensing signal exceeds a reference voltage level.
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Accused Products
Abstract
A circuit for supplying power to a fluorescent lamp. A control system comprises a buck regulator for supplying a buck current, an inverter circuit for receiving the buck current and for generating a lamp voltage, a circuit for sensing a current in a fluorescent lamp, a circuit for sensing a no lamp condition, and a controller for controlling the buck regulator and the inverter. The circuit for sensing a no lamp condition monitors a voltage level at the inverter transformer. The controller is coupled to the circuit for sensing a no lamp condition. If a no lamp condition is detected, the controller responds by shutting itself down. The controller can be reactivated by toggling an on/off signal to reset a latch.
183 Citations
20 Claims
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1. A circuit for supplying power to a fluorescent lamp comprising:
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a. controller circuit; b. a buck regulator for forming a buck current signal wherein the buck regulator is coupled to be controlled by the controller circuit; c. an inverter for forming a lamp signal, the inverter having an input node, wherein the input node is coupled to receive the buck current signal; d. a sensing circuit for forming a sensing signal representative of a voltage at the input node; and e. means for deactivating the controller circuit if the sensing signal exceeds a reference voltage level. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A circuit for supplying power to a fluorescent lamp comprising:
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a. a controller; b. a buck regulator for forming a buck current signal coupled to be controlled by the controller; c. a transformer having a primary winding and a secondary winding, the primary winding having a center tap, wherein the center tap is coupled to receive the buck current signal; and d. means for shutting down the controller if no fluorescent lamp is coupled to the secondary winding, the means for shutting down coupled to the center tap. - View Dependent Claims (14)
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15. A circuit for supplying power to a fluorescent lamp comprising:
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a. a controller for controlling a circuit for supplying voltage to a fluorescent lamp; b. a controller power supply circuit coupled to the controller; and c. a circuit coupled to the controller power supply circuit for shutting down the controller power supply circuit when no fluorescent lamp is coupled to the circuit for supplying voltage to the fluorescent lamp. - View Dependent Claims (16, 17)
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18. A circuit for supplying power to a fluorescent lamp comprising:
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a. a controller for controlling a circuit for supplying voltage to a fluorescent lamp; b. a controller power supply circuit coupled to the controller; and c. a circuit coupled to the controller power supply circuit for shutting down the controller power supply circuit when a defective fluorescent lamp is coupled to the circuit for supplying voltage to the fluorescent lamp. - View Dependent Claims (19, 20)
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Specification