Lamp with integral voltage converter having phase-controlled dimming circuit 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 voltage controlled resistor that varies a resistance in the phase-controlled dimming circuit as the first voltage varies so as to maintain the second voltage substantially constant. 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.
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 phase-controlled dimming means for reducing an RMS load voltage at said light emitting element, said phase-controlled dimming means includes means for varying a resistance in said voltage converter in reaction to variation of the first line voltage.
2. The lamp of claim 1 , wherein said phase-controlled dimming means comprises a circuit that has a resistor, a capacitor, a diac, and a triac that is triggered by said diac.
3. The lamp of claim 2 , wherein said resistor has a resistance that is fixed and that is based on the first line voltage.
4. The lamp of claim 2 , wherein said resistor has a resistance that varies in response to variation of the first line voltage so as to maintain the RMS load voltage substantially constant.
5. The lamp of claim 1 wherein said means for varying a resistance comprises a voltage controlled resistor that varies a resistance in said phase-controlled dimming circuit when the first line voltage varies so as to maintain the RMS load voltage substantially constant.
6. An incandescent lamp comprising:
a base with a lamp terminal;
a light-transmitting envelope attached to said base and housing a light emitting element; and
a lamp voltage conversion circuit for converting a first line voltage at said lamp terminal to a second RMS load voltage lower than the first line voltage and that operates said light emitting element, said lamp voltage conversion circuit being within said base and connected between said lamp terminal and said light emitting element,
said voltage conversion circuit including a phase-controlled dimming circuit that has a capacitor, a diac, a triac that is triggered by said diac, and a voltage controlled resistor that varies a resistance in said phase-controlled dimming circuit when the first line voltage varies so as to maintain the second voltage substantially constant.
7. The incandescent lamp of claim 6 , wherein said voltage controlled resistor (VCR) is a junction field effect transistor VCR.
8. The incandescent lamp of claim 6 , wherein said voltage conversion circuit is an integrated circuit.