Alternating current light emitting device

• US 8,598,799 B2
• Filed: 12/18/2008
• Issued: 12/03/2013
• Est. Priority Date: 12/19/2007
• Status: Active Grant

• Current Assignee: Epistar Corporation
• Original Assignee: Epistar Corporation
• Inventors: Tai, Sheng-Chieh, Yeh, Wen-Yung, Chan, Yi-Jen
• Primary Examiner(s): Le, Tung X
• Application Number:
  US12/337,755
• Publication Number:
  US 20090160370A1
• Time in Patent Office: 1,811 Days
• Field of Search: 315/185.R, 315/185.S, 315/187, 315/192, 315/210, 315/246, 315/291, 315/294, 315/312
• US Class Current: 315/246
• CPC Class Codes: G09G 3/3696 Generation of voltages supplied to electrode drivers
• CPC Class Codes: H05B 41/16 in which the lamp is fed by dc or by low-frequency ac, e.g. by 50 cycles/sec ac, or with network frequencies
• CPC Class Codes: H05B 45/00 Circuit arrangements for operating light-emitting diodes [LED]

Abstract

An alternating current (AC) light emitting device includes an AC light emitting diode (LED) module and a waveform modulation unit. The AC LED module includes at least two sets of micro-diodes. The waveform modulation unit coupled between the AC LED module and an AC voltage source modulates a waveform of the AC voltage source.

Claims

1. An alternating current (AC) light emitting device, comprising:

an AC light emitting diode (LED) module comprising at least two sets of micro-diodes; and

a waveform modulation unit, coupled between the AC LED module and an AC voltage source, for increasing the full width at half maximum (FWHM) of a waveform of the AC voltage source;

wherein the AC voltage source modulated by the waveform modulation unit turns on one of the two sets of micro-diodes for a first time in a positive half cycle, and turns on the other one of the two sets of micro-diodes for a second time in a negative half cycle.

2. The AC light emitting device according to claim 1, wherein the waveform modulation unit and the AC LED module are integrated within a chip.

3. The AC light emitting device according to claim 1, wherein the waveform modulation unit and the AC LED module are disposed in a package.

4. The AC light emitting device according to claim 1, wherein the micro-diodes are micro-light emitting diodes.

5. The AC light emitting device according to claim 1, wherein the first time is longer than the second time.

6. The AC light emitting device according to claim 1, wherein the first time is shorter than the second time.

7. The AC light emitting device according to claim 1, wherein the waveform modulation unit adjusts the waveform of the AC voltage source into a square wave.

8. The AC light emitting device according to claim 1, wherein the first time or the second time is at least 0.005 second.