Capacitive full-wave circuit for LED light strings

• US 9,955,538 B2
• Filed: 04/04/2014
• Issued: 04/24/2018
• Est. Priority Date: 11/04/2008
• Status: Active Grant

• Current Assignee: 1 Energy Solutions Incorporated
• Original Assignee: 1 Energy Solutions Incorporated
• Inventors: Yu, Jing Jing, Ma, Lianfeng
• Primary Examiner(s): Taningco, Alexander H
• Assistant Examiner(s): Luque, Renan
• Application Number:
  US14/245,556
• Publication Number:
  US 20140250685A1
• Time in Patent Office: 1,481 Days
• Field of Search: 315185 S, 315185 R, 315294, 315200 R, 315205, 315291, 315307, 315172, 315187, 315192, 315193, 315207, 315312, 315DIG 4, 315123, 315135, 315200 A, 315201, 315209 CD, 315224, 315227 R, 315240, 315244, 315247, 315250, 315287, 315 51, 363 61, 363143, 363 17, 363101, 363 20, 363 2112, 363 37, 363 39, 363 44, 363 47, 363 90, 362640, 362800, 362227, 362235, 36224901, 36224916, 36224917, 362265, 362545, 362612
• 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 inductor to a first power lead of said AC current source and not to a full bridge rectifier;

connecting a first lead of a first capacitor to a second lead of said first inductor;

connecting a second lead of said first capacitor to said LED light string module and not to a full bridge rectifier, so that said first inductor and said first capacitor are connected in series between said first power lead and said LED string module;

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 light string module without an intervening resistor;

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

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

connecting a first lead of a second capacitor to a second lead of said second inductor;

connecting a second lead of said second capacitor to an anode of a second diode without an intervening resistor and a second end of said LED light string module and not to a full bridge rectifier, so that said second inductor and said second capacitor are connected in series between said first power lead and said LED light string module;

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 without a resistor that is sufficient to limit current through said LED light string module without a resistor 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 without a resistor 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;

selecting an inductance for said first inductor that has an impedance that is added to an impedance of said first capacitor that is sufficient to limit current spikes from being transmitted to said LED module, said current spikes occurring from charging and discharging said first capacitor with said AC current source;

selecting an inductance for said second inductor that has an impedance that is added to an impedance of said second capacitor that is sufficient to limit current spikes from being transmitted to said LED module, said current spikes occurring from charging and discharging said second capacitor with said AC current source.

2. 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.

3. The method of claim 1 further comprising:

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

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