Capacitive full-wave circuit for LED light strings

• US 8,723,432 B2
• Filed: 05/29/2012
• Issued: 05/13/2014
• Est. Priority Date: 11/04/2008
• Status: Active Grant

• Current Assignee: Santa's Best
• Original Assignee: 1 Energy Solutions Incorporated
• Inventors: Yu, Jing Jing, Ma, Lianfeng
• Primary Examiner(s): Taningco, Alexander H
• Assistant Examiner(s): LO, CHRISTOPHER KWOK YEUNG
• Application Number:
  US13/482,090
• Publication Number:
  US 20120233854A1
• Time in Patent Office: 714 Days
• Field of Search: 315/291, 315/299, 315/360, 315/185.R, 315/192, 315/200.R, 315/312, 315/187, 315/205, 315/246, 315/207, 315/206, 315/200.A, 315/324, 362/227, 362/230, 362/231, 362/234, 362/235, 362/236, 362/237, 362/240, 362/252, 362/569, 362/810, 362/807, 362/812, 362/808
• US Class Current: 315/185.R
• CPC Class Codes: H05B 45/37 Converter circuits
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]
• CPC Class Codes: Y10T 29/49117 Conductor or circuit manufacturing

Abstract

A capacitive full-wave circuit for LED light strings makes use of capacitors and diodes together to drive a LED string with full AC waves. Different from the conventional four-diode full-wave rectifying circuit, one embodiment of capacitive full-wave circuit includes two capacitors and two diodes. Because of the large imaginary impedance, the capacitors not only limit and the voltage and current through the LEDs, but also consume almost no electrical power. The electrical current-voltage performance can be further improved by introducing four resistors with a cost of some additional power consumption. A LED light string module with the capacitive full-wave circuit is also presented, with the capacitive full-wave circuit integrated inside of a front power plug and a back power socket.

Claims

1. A method of driving a series of LEDs in an LED light string module using an AC current source and minimizing power loss comprising:

providing a first adapter that is not connected to a full wave rectifier comprising;

connecting a first lead of a first capacitor to a first power lead of said AC current source and not to a full bridge rectifier;

connecting a second lead of said first capacitor to a first end of said LED string module and not to a full bridge rectifier;

connecting an anode of a first diode, which is not part of a full bridge rectifier, to a second power lead of said AC current source;

connecting a cathode of said first diode to said second lead of said first capacitor and said first end of said LED string module;

providing a second adapter that is not connected to a full wave rectifier comprising;

connecting a first lead of a second capacitor to said first power lead of said AC current source and not to a full bridge rectifier;

connecting a second lead of said second capacitor to an anode of a second diode and a second end of said LED light string module and not to a full bridge rectifier;

connecting a cathode of said second diode, which is not part of a full bridge rectifier, to said second power lead of said AC current source;

selecting a capacitance tor said first capacitor that creates an impedance between said first power lead and said LED light string module that is sufficient to limit current through said LED light string module to prevent damage to said LED light string module and cause a positive voltage to be applied to said LED light string module whenever a voltage level on said first power lead exceeds a voltage level on said second power lead, so that said first capacitor functions as a voltage divider, which divides voltages between said first capacitor and said series of LEDs in said LED light string module, which allows said first adapter to be used with different numbers of LEDs in said LED light string module;

selecting a capacitance for said second capacitor that creates an impedance between said first power lead and said LED light string module that is sufficient to limit current through said LED light string module to prevent damage to said LED light string module and cause a positive voltage to be applied to said LED light string module whenever said voltage level on said second power lead exceeds said voltage level on said first power lead, so that said second capacitor functions as a voltage divider that divides voltages generated by said AC current source between said second capacitor and said series of LEDs in said LED light string module, which allows said second adapter to be used with different numbers of LEDs in said light string module;

connecting a first inductor in series between said first lead of said first capacitor and said first power lead;

connecting a second inductor in series between a first lead of said second capacitor and said first power lead.

3. The method of claim 1 further comprising:

encapsulating said first capacitor and said first diode in a plug of a light string;

encapsulating said second capacitor and said second diode in a socket of a light string.

4. The method of claim 1 further comprising:

encapsulating said first capacitor and said first diode in said first adapter module that is connected to a plug and said LED light string module;

encapsulating said second capacitor and said second diode in said second adapter module that is connected to a socket and said LED light string module.

2. A method of driving a series of LEDs in an LED light string module using an AC current source and minimizing power loss comprising:

providing a first adapter that is not connected to a full wave rectifier comprising;

connecting a first lead of a first capacitor to a first power lead of said AC current source and not to a full bridge rectifier;

connecting a second lead of said first capacitor to a first end of said LED string module and not to a full bridge rectifier;

connecting an anode of a first diode, which is not part of a full bridge rectifier, to a second power lead of said AC current source;

connecting a cathode of said first diode to said second lead of said first capacitor and said first end of said LED string module;

providing a second adapter that is not connected to a full wave rectifier comprising;

connecting a first lead of a second capacitor to said first power lead of said AC current source and not to a full bridge rectifier;

connecting a second lead of said second capacitor to an anode of a second diode and a second end of said LED light string module and not to a full bridge rectifier;

connecting a cathode of said second diode, which is not part of a full bridge rectifier, to said second power lead of said AC current source;

selecting a capacitance for said first capacitor that creates an impedance between said first power lead and said LED light string module that is sufficient to limit current through said LED light string module to prevent damage to said LED light string module and cause a positive voltage to be applied to said LED light string module whenever a voltage level on said first power lead exceeds a voltage level on said second power lead, so that said first capacitor functions as a voltage divider, which divides voltages between said first capacitor and said series of LEDs in said LED light string module, which allows said first adapter to be used with different numbers of LEDs in said LED light string module;

selecting a capacitance for said second capacitor that creates an impedance between said first power lead and said LED light string module that is sufficient to limit current through said LED light string module to prevent damage to said LED light string module and cause a positive voltage to be applied to said LED light string module whenever said voltage level on said second power lead exceeds said voltage level on said first power lead, so that said second capacitor functions as a voltage divider that divides voltages generated by said AC current source between said second capacitor and said series of LEDs in said LED light string module, which allows said second adapter to be used with different numbers of LEDs in said light string module

connecting a first resistor in series between said first lead of said first capacitor and said first power lead;

connecting a second resistor in parallel with said first capacitor;

connecting a third resistor in series between said first lead of said second capacitor and said first power lead;

connecting a fourth resistor in parallel with said second capacitor.

5. The method of claim 2 further comprising:

encapsulating said first capacitor and said first diode in a plug of a light string;

encapsulating said second capacitor and said second diode in a socket of a light string.

6. The method of claim 2 further comprising:

encapsulating said first capacitor and said first diode in said first adapter module that is connected to a plug and said LED light string module;

encapsulating said second capacitor and said second diode in said second adapter module that is connected to a socket and said LED light string module.