Solid-state lighting apparatus with filament imitation for use with florescent ballasts
View Patent ↗A lighting apparatus includes a solid-state lighting circuit, a ballast connection port including first and second terminals and a filament-imitating impedance coupled between the first and a second terminals of the ballast connection port and to an input terminal of the solid-state lighting circuit. The filament-imitating impedance may be configured to transfer power at a nominal frequency of an output produced by the ballast and to provide an impedance between the first and second terminals of the ballast connection port that prevents shutdown of the ballast. In some embodiments, the filament-imitating impedance may vary with temperature, e.g., the filament-imitating impedance may be configured to imitate a temperature dependence of a fluorescent tube filament. The lighting apparatus may be included in a fluorescent lamp replacement lamp.
1. A lighting apparatus comprising:
a solid-state lighting circuit;
a ballast connection port comprising first and second terminals; and
a filament-imitating impedance coupled between the first and second terminals of the ballast connection port and to an input terminal of the solid-state lighting circuit and comprising a resistor coupled in series with a capacitor between one of the first and second terminals and the input terminal of the solid-state lighting circuit.
2. The apparatus of claim 1 , wherein the filament-imitating impedance comprises a capacitor.
3. The apparatus of claim 2 , wherein the capacitor is configured to transfer power at a nominal frequency of an output produced by the ballast and to provide an impedance between the first and second terminals of the ballast connection port that prevents shutdown of the ballast.
4. The apparatus of claim 2 , wherein a capacitance provided between the first and second terminals of the ballast connection port is in a range from about 0.1 μF to about 4 μF.
5. The apparatus of claim 2 , wherein the resistor comprises a first resistor and wherein the filament-imitating impedance further comprises a second resistor coupled in parallel with the capacitor and the first resistor and having a resistance small enough to prevent shutdown of the ballast and large enough to inhibit operation of a starter circuit attached to the apparatus.
6. The apparatus of claim 2 , wherein the resistor comprises a temperature-varying resistor.
7. The apparatus of claim 1 , where the filament-imitating impedance varies with temperature.
8. The apparatus of claim 7 , wherein the filament-imitating impedance is configured to imitate a temperature dependence of a fluorescent tube filament.
9. The apparatus of claim 1 , wherein the ballast connection port comprises a first ballast connection port, wherein the filament-imitating impedance comprises a first filament-imitating impedance, and wherein the apparatus further comprises:
a second ballast connection port comprising first and second terminals; and
a second filament-imitating impedance coupled between the first and a second terminal of the second ballast connection port and to an input terminal of the solid-state lighting circuit and configured transfer power between a ballast connected to the second ballast connection port and the solid-state lighting circuit.
10. A fluorescent replacement lamp comprising the apparatus of claim 1 , wherein the first and second terminals of the ballast connection port comprise respective first and second pins configured to be connected to a fluorescent lamp connector.
11. The apparatus of claim 1 , wherein the temperature-varying resistor comprises a positive temperature coefficient (PTC) resistor.
12. A lighting apparatus comprising:
a solid-state lighting circuit;
a ballast connection port comprising first and second terminals;
a filament-imitating impedance having a first terminal coupled to the first terminal of the ballast connection port; and
a low-frequency blocking impedance having a first terminal coupled to a second terminal of the filament-imitating impedance and the second terminal of the ballast connection port and a second terminal coupled to an input terminal of the solid-state lighting circuit,
wherein the low-frequency blocking impedance is configured to block at least one frequency component having a frequency of about 60 Hz or less.
13. The apparatus of claim 12 , wherein the filament-imitating impedance comprises a capacitor.
14. The apparatus of claim 13 , wherein the filament-imitating impedance further comprises a resistor coupled in parallel with the capacitor.
15. The apparatus of claim 13 , wherein the capacitor comprises a first capacitor and wherein the low-frequency blocking impedance comprises a second capacitor.
16. The apparatus of claim 15 , further comprising a resistor coupled in parallel with the second capacitor.
17. The apparatus of claim 12 , wherein the solid-state lighting circuit comprises:
a rectifier circuit having an input terminal coupled to the second terminal of the low-frequency blocking impedance; and
at least one light emitting diode (LED) coupled to an output port of the rectifier circuit.
18. The apparatus of claim 17 , wherein the solid-state lighting circuit further comprises a matching circuit.
19. The apparatus of claim 18 , wherein the matching circuit comprises:
a capacitor coupled in parallel with the output port of the rectifier circuit; and
an inductor coupled between the capacitor and the at least one LED.
20. The apparatus of claim 19 , wherein the at least one LED comprises at least one LED string.
21. A fluorescent replacement lamp comprising the apparatus of claim 12 , wherein the first and second terminals of the ballast connection port comprise respective first and second pins configured to be connected to a fluorescent lamp connector.
22. A lighting apparatus comprising:
at least one LED;
a ballast connection port;
a filament-imitating impedance coupled between first and second terminals of the ballast connection port, wherein the filament-imitating impedance is configured to mimic the impedance of a filament of a fluorescent lamp while transferring power between the ballast connection port and the at least one LED; and
a resonant matching circuit coupled between the filament-imitating impedance and the at least one LED.
23. The apparatus of claim 22 , wherein the filament-imitating impedance comprises a capacitor.
24. The apparatus of claim 23 , wherein the filament-imitating impedance further comprises a resistor coupled in parallel with the capacitor.
25. The apparatus of claim 22 , further comprising a rectifier circuit coupled between the at least one LED and the filament-imitating impedance.
26. The apparatus of claim 25 , wherein the resonant matching circuit comprises an inductor coupled in series with the at least one LED and a capacitor coupled in parallel with the output port of the rectifier circuit.
27. A fluorescent replacement lamp comprising the apparatus of claim 22 , wherein the first and second terminals of the ballast connection port comprise respective first and second pins configured to be connected to a fluorescent lamp connector.
28. The apparatus of claim 22 , wherein the resonant matching circuit is configured to provide an impedance between the first and second terminals of the ballast connection port to improve power transfer to the at least one LED.