Single transistor ballast with filament preheating
First Claim
Patent Images
1. A ballast circuit for driving a gas discharge lamp, comprising:
- a power source, connected to an alternating current supply, of a pulsating and rectified voltage;
an energy storage capacitor having two ends with one of said ends connected to a circuit common;
an energy storage inductor having a first terminal that is connected to said power source and having a second terminal that is connected to the other end of said energy storage capacitor;
a switch that has one end connected to said first terminal of said energy storage inductor and an opposite end that is connected to said circuit common;
a resonant circuit that is coupled to said energy storage inductor for energizing the gas discharge lamp, said resonant circuit having a predetermined resonant frequency;
a switch control circuit for opening and closing said switch at a rate that is a function of at least a DC current level; and
a current changing circuit comprising a resistor switching circuit for changing said predetermined DC current level for a predetermined time interval after connecting said alternating current supply such that said resonant circuit operates at a frequency that is different than said predetermined resonant frequency for at least said predetermined time interval.
3 Assignments
0 Petitions
Accused Products
Abstract
A ballast circuit for driving a gas discharge having a source of pulsating and rectified AC (20), an energy storage circuit (30), a switch (40) that can have one end connected to an energy storage inductor and an opposite end that can be connected to circuit common; a control circuit (50) for opening and closing the switch (40) at a rate that is a function of at least a DC control current, a resonant circuit (60) that is coupled to the energy storage circuit (30) for energizing the gas discharge lamp.
18 Citations
18 Claims
-
1. A ballast circuit for driving a gas discharge lamp, comprising:
-
a power source, connected to an alternating current supply, of a pulsating and rectified voltage; an energy storage capacitor having two ends with one of said ends connected to a circuit common; an energy storage inductor having a first terminal that is connected to said power source and having a second terminal that is connected to the other end of said energy storage capacitor; a switch that has one end connected to said first terminal of said energy storage inductor and an opposite end that is connected to said circuit common; a resonant circuit that is coupled to said energy storage inductor for energizing the gas discharge lamp, said resonant circuit having a predetermined resonant frequency; a switch control circuit for opening and closing said switch at a rate that is a function of at least a DC current level; and a current changing circuit comprising a resistor switching circuit for changing said predetermined DC current level for a predetermined time interval after connecting said alternating current supply such that said resonant circuit operates at a frequency that is different than said predetermined resonant frequency for at least said predetermined time interval. - View Dependent Claims (2, 3, 4, 5)
-
-
6. A ballast circuit for driving a gas discharge lamp, comprising:
-
a power source, connected to an alternating current supply, of a pulsating and rectified voltage; an energy storage capacitor having two ends with one of said ends connected to a circuit common; an energy storage inductor having a first terminal that is connected to said power source and having a second terminal that is connected to the other end of said energy storage capacitor; a switch that has one end connected to said first terminal of said energy storage inductor and an opposite end that is connected to said circuit common; a resonant circuit that is coupled to said energy storage inductor for energizing the gas discharge lamp, said resonant circuit having a predetermined resonant frequency; a switch control circuit for opening and closing said switch at a rate that is a function of at least a DC current level; and a current changing circuit for changing said DC current level after connecting said alternating current such that said switch operates at a rate to achieve resonance only after a predetermined delay, said current changing circuit comprising; a time delay circuit having a predetermined time interval; a transistor switch that opens and closes in response to said time delay circuit; and a resistance network for producing said DC current level from a reference voltage, said resistance network having a first node that is connected to said reference voltage, having a second node connected to said switch control circuit and having a third node that is connected to a circuit common through said transistor switch, such that said DC current level changes in response to the operation of said time delay circuit. - View Dependent Claims (7, 8)
-
-
9. A ballast circuit for driving a gas discharge lamp, comprising:
-
a power source, connected to an alternating current supply, of a pulsating and rectified voltage; an energy storage capacitor having two ends with one of said ends connected to a circuit common; an energy storage inductor having a first terminal that is connected to said power source and having a second terminal that is connected to the other end of said energy storage capacitor; a switch that has one end connected to said first terminal of said energy storage inductor and an opposite end that is connected to said circuit common; a resonant circuit that is coupled to said energy storage inductor for energizing the gas discharge lamp, said resonant circuit having a predetermined resonant frequency; a switch control circuit for opening and closing said switch at a rate that is a function of at least a DC current level; and a current changing circuit for changing said DC current level after connecting said alternating current such that said switch operates at a rate to achieve resonance only after a predetermined delay, said current changing circuit comprising a resistance network for producing said DC current level from a reference voltage, said resistance network having a first node that is connected to said reference voltage, having a second node that is connected to said control circuit and having a third node that is connected to a circuit common through a transistor switch, such that said current level changes in response to the operation of said time delay circuit. - View Dependent Claims (10, 11)
-
-
12. A ballast circuit for using an AC power source to operate a gas discharge lamp of the type having at least one heating element therein, comprising:
-
a power circuit for converting the AC power source to a pulsating, rectified, power-factor corrected output; an energy storage inductor circuit that is connected to said output of said power circuit and that comprises a clamping winding and a primary winding having one of its ends connected to said output of said power circuit; an electronic switch that connects a circuit common to said one end of said primary winding and that operates in response to a DC control current; a storage capacitor connected between the other end of said primary winding and said circuit common; a resonant circuit that is connected to said energy storage inductor circuit and that energizes the gas discharge lamp;
said resonant circuit having a resonant frequency that is achieved when said DC control current is at a predetermined DC level; and
a starting circuit for changing said DC control current level for a predetermined time interval before operating said resonant circuit at resonance, said starting circuit comprising a switching circuit for supplying a control current that is higher than said predetermined DC level and for supplying a control current equal to said predetermined level at the end of said predetermined time interval. - View Dependent Claims (13, 14, 15, 16, 17)
-
-
18. A ballast circuit for using an AC power source to operate a gas discharge lamp of the type having heating element therein, comprising:
-
a power circuit for converting the AC power source to a pulsating, rectified, power-factor corrected output; an energy storage inductor circuit that is connected to said output of said power circuit, said energy storage inductor circuit comprising;
a primary winding having one end connected to said output of said power circuit and having an opposite end connected to a circuit common through an energy storage capacitor, a clamping winding having a first clamping winding terminal that is connected to said circuit common and having a second clamping winding terminal that is connected through a clamping diode to said opposite end of said primary winding, and an auxiliary capacitor that is connected between said second clamping winding terminal and said one end of said primary winding;an electronic switch that connects a circuit common to said one end of said primary winding; a control for opening and closing said electronic switch in response to a DC control current; a resonant circuit that is connected to said one end of said primary winding and that energizes the gas discharge lamp, said resonant circuit having a resonant frequency that is achieved when said DC control current is at a predetermined DC level; and a starting circuit for changing said DC control current for a predetermined time interval after energizing said power circuit, said starting circuit comprising;
a time delay capacitor, a startup switch that opens and closes in response to the voltage across said time delay capacitor, and a resistance network that produces said DC control current from a reference voltage and that has a node connected to said circuit common through said startup switch, such that said DC control current changes at least in response to the operation of said startup switch.
-
Specification