AC-powered LED light engine

• US 9,723,671 B2
• Filed: 04/15/2016
• Issued: 08/01/2017
• Est. Priority Date: 02/17/2014
• Status: Expired due to Fees

• Current Assignee: Photalume Inc.
• Original Assignee: Peter W. Shackle
• Inventors: Shackle, Peter W.
• Primary Examiner(s): Hammond, Crystal L
• Application Number:
  US15/130,033
• Publication Number:
  US 20160234898A1
• Time in Patent Office: 473 Days
• Field of Search: None
• CPC Class Codes: H05B 45/395 Linear regulators
• CPC Class Codes: H05B 45/40 Details of LED load circuits
• CPC Class Codes: H05B 45/48 having LEDs organised in strings and incorporating parallel shunting devices
• 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: Y02B 20/40 Control techniques providing energy savings, e.g. smart controller or presence detection

Abstract

AC LED light engines powered directly from the AC power line contain circuitry of resistors, capacitors, diodes and transistors which enables a single string LEDs connected to series to efficiently produce light with a relatively low level of flicker as perceived by the human eye. The LEDs are driven by a current which is alternately capacitively-limited and resistively-limited. Capacitively-limited pulses of current are interposed between resistively-limited pulses of current so that the resulting output current ripple is at frequencies of 240 Hz or above which the human eye cannot perceive. The combination of resistively-limited current and capacitively-limited current results in a current drain from the power line which is generally sinusoidal and can have a power factor in excess of 0.70.

Claims

1. A driverless LED light engine comprising:

a plurality of single LED devices connected in series to form an LED string, with the string defined as including a plurality of LED substrings connected anode to cathode and connected to the ac power line; and

a plurality of resistors and at least two separate bias capacitors coupled between the ac power line and selected LED substrings such that during each ac power line half cycle two distinct types of LED current peaks are present, one type of LED current peak being capacitively-limited displacement current attributed to one of the at least two separate bias capacitors, and another type of LED current peak being galvanic current passing through at least one of the plurality of the resistors.

2. The driverless LED light engine as defined in claim 1 wherein the light engine further comprises a bridge rectifier as the means of connecting the ac power line to the resistors.

3. The driverless LED light engine as defined in claim 1 wherein the specific values of the plurality of resistors and the at least two separate bias capacitors are selected such that the peak amplitudes of said galvanic current and said displacement current are approximately the same.