Lamp with integral voltage converter having phase-controlled dimming circuit with hysteresis control for reducing RMS load voltage
View Patent ↗An incandescent lamp includes a lamp voltage conversion circuit within the lamp and connected to a lamp terminal, where the voltage conversion circuit converts a first line voltage at the lamp terminal to a second RMS load voltage usable by a light emitting element of the lamp. The voltage conversion circuit includes a triac phase-controlled dimming circuit, which in turn includes a hysteresis control network. The voltage conversion circuit may be an integrated circuit that is in the lamp base and connected between the lamp terminal and the light emitting element. The triac phase-controlled dimming circuit may be built for a specific line voltage.
1. A lamp comprising a lamp voltage converter in the lamp and connected between a lamp terminal and a light emitting element, said voltage converter converting a first line voltage at said lamp terminal to a load voltage that operates said light emitting element, said voltage converter including a phase-controlled dimming circuit for reducing an RMS load voltage at said light emitting element, the phase-controlled dimming circuit including means for reducing hysteresis in the phase-controlled dimming circuit.
2. The lamp of claim 1 , wherein said phase-controlled dimming circuit comprises a first RC network with a resistor and a capacitor, a diac connected between the resistor and the capacitor, and a triac connected in parallel with the first RC network.
3. The lamp of claim 2 , wherein said means for reducing hysteresis comprises a second RC network connected in parallel with said first RC network and wherein said diac is connected between a resistor and a capacitor connected in series in said second RC network.
4. The lamp of claim 2 , wherein said means for reducing hysteresis comprises a second network connected in parallel with said first RC network, said second network including a resistor and a diode connected to each other in series, and wherein said diac is connected between the resistor and the diode of said second network.
5. The lamp of claim 4 , wherein said means for reducing hysteresis further comprises a third network connected in parallel with said second network, said third network including a resistor and a diode connected to each other in series, and wherein said diac is connected between the resistor and the diode of said third network.
6. The lamp of claim 2 , wherein a resistance of said resistor in said first RC network is fixed and is based on the first line voltage at said lamp terminal.
7. The lamp of claim 1 , further comprising a base and a light-transmitting envelope, and wherein said voltage converter is within said base.
8. The lamp of claim 7 , wherein said voltage converter is an integrated circuit.
9. An incandescent lamp comprising:
a lamp voltage conversion circuit within the lamp and connected to a lamp terminal, said voltage conversion circuit converting a first line voltage at said lamp terminal to a load voltage; and
said voltage conversion circuit including a phase-controlled dimming circuit for reducing an RMS load voltage, said phase-controlled dimming circuit comprising,
a first RC network with a resistor and a capacitor connected in series, a diac with a first terminal connected between the resistor and the capacitor, and a triac connected in parallel with the first RC network and that is triggered by a second terminal of said diac when breakover voltage is achieved at said capacitor, and
a second network connected in parallel with said first RC network, said second network having a resistor and second element connected in series, said first terminal of said diac being connected between the resistor and the second element of said second network.
10. The lamp of claim 9 , further comprising a base and a light-transmitting envelope, and wherein said voltage conversion circuit is within said base.
11. The lamp of claim 9 , wherein said second element of said second network is a capacitor and wherein said first terminal of said diac is connected between the resistor and the capacitor of said second network through a resistor.
12. The lamp of claim 9 , wherein said second element of said second network is a diode and wherein said first terminal of said diac is connected between the resistor and the diode of said second network through a further diode.
13. The lamp of claim 12 , wherein said phase-controlled dimming circuit further comprises a third network connected in parallel with said second network, said third network including a resistor and a diode connected to each other in series, and wherein said first terminal of said diac is connected between the resistor and the diode of said third network through yet a further diode.
14. The lamp of claim 9 , wherein said voltage conversion circuit is an integrated circuit.