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Article: On the color stability of phosphor-converted white LEDs under DC, PWM, and bilevel drive

TitleOn the color stability of phosphor-converted white LEDs under DC, PWM, and bilevel drive
Authors
KeywordsDriving method
LED
LED color
phosphor-converted (pc) LED
white LED
Issue Date2012
Citation
Ieee Transactions On Power Electronics, 2012, v. 27 n. 2, p. 974-984 How to Cite?
AbstractMost commercial white LEDs are made from nitride-based blue LEDs coated with yttrium aluminium garnet phosphor, which produce spectra that shift in opposite directions under the influences of drive current and junction temperature changes. This property gives rise to different emitted spectra, hence chromaticity properties, when the LED is driven/dimmed by different current waveforms. By using a commercial white LED sample, LUXEON K2, the effects of drive current and junction temperature on the changes of chromaticity coordinates are studied experimentally. The impact of dc, pulse width modulation (PWM), and bilevel current waveform is discussed through a graphical analysis, followed by experimental verification. It is proven that dc offers the best color stability over dimming due to the counteracting influences of drive current and junction temperature variations, whereas an LED constantly suffers from noneliminable chromaticity changes when driven by the PWM. Theoretical explanations are given to justify these cases, and it is found that, for the case of dc drive, an ideal heat sinks thermal resistance can be selected based on a simple equation to minimize the overall chromaticity change over dimming. This paper provides an in-depth discussion on the relations between the chromaticity properties of phosphor-converted (pc) white LEDs and the driving/dimming methods used. © 2011 IEEE.
Persistent Identifierhttp://hdl.handle.net/10722/148915
ISSN
2015 Impact Factor: 4.953
2015 SCImago Journal Rankings: 3.005
ISI Accession Number ID
Funding AgencyGrant Number
University Grants Committee of the Hong Kong Special Administrative Region, Research Grants CouncilPolyU 5272/07E
Funding Information:

This work was supported by the University Grants Committee of the Hong Kong Special Administrative Region, Research Grants Council Earmarked Research Grant under Grant PolyU 5272/07E. Recommended for publication by Associate Editor M. Ponce-Silva.

References

 

DC FieldValueLanguage
dc.contributor.authorLoo, KHen_HK
dc.contributor.authorLai, YMen_HK
dc.contributor.authorTan, SCen_HK
dc.contributor.authorTse, CKen_HK
dc.date.accessioned2012-06-20T06:16:18Z-
dc.date.available2012-06-20T06:16:18Z-
dc.date.issued2012en_HK
dc.identifier.citationIeee Transactions On Power Electronics, 2012, v. 27 n. 2, p. 974-984en_HK
dc.identifier.issn0885-8993en_HK
dc.identifier.urihttp://hdl.handle.net/10722/148915-
dc.description.abstractMost commercial white LEDs are made from nitride-based blue LEDs coated with yttrium aluminium garnet phosphor, which produce spectra that shift in opposite directions under the influences of drive current and junction temperature changes. This property gives rise to different emitted spectra, hence chromaticity properties, when the LED is driven/dimmed by different current waveforms. By using a commercial white LED sample, LUXEON K2, the effects of drive current and junction temperature on the changes of chromaticity coordinates are studied experimentally. The impact of dc, pulse width modulation (PWM), and bilevel current waveform is discussed through a graphical analysis, followed by experimental verification. It is proven that dc offers the best color stability over dimming due to the counteracting influences of drive current and junction temperature variations, whereas an LED constantly suffers from noneliminable chromaticity changes when driven by the PWM. Theoretical explanations are given to justify these cases, and it is found that, for the case of dc drive, an ideal heat sinks thermal resistance can be selected based on a simple equation to minimize the overall chromaticity change over dimming. This paper provides an in-depth discussion on the relations between the chromaticity properties of phosphor-converted (pc) white LEDs and the driving/dimming methods used. © 2011 IEEE.en_HK
dc.languageengen_US
dc.relation.ispartofIEEE Transactions on Power Electronicsen_HK
dc.rightsCreative Commons: Attribution 3.0 Hong Kong License-
dc.subjectDriving methoden_HK
dc.subjectLEDen_HK
dc.subjectLED coloren_HK
dc.subjectphosphor-converted (pc) LEDen_HK
dc.subjectwhite LEDen_HK
dc.titleOn the color stability of phosphor-converted white LEDs under DC, PWM, and bilevel driveen_HK
dc.typeArticleen_HK
dc.identifier.emailTan, SC:sctan@hku.hken_HK
dc.identifier.authorityTan, SC=rp01606en_HK
dc.description.naturepublished_or_final_versionen_US
dc.identifier.doi10.1109/TPEL.2010.2086080en_HK
dc.identifier.scopuseid_2-s2.0-84855695290en_HK
dc.identifier.hkuros205637-
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-84855695290&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume27en_HK
dc.identifier.issue2en_HK
dc.identifier.spage974en_HK
dc.identifier.epage984en_HK
dc.identifier.isiWOS:000299076400027-
dc.publisher.placeUnited Statesen_HK
dc.identifier.scopusauthoridLoo, KH=7003558724en_HK
dc.identifier.scopusauthoridLai, YM=7401512093en_HK
dc.identifier.scopusauthoridTan, SC=26642772000en_HK
dc.identifier.scopusauthoridTse, CK=7103295097en_HK

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