TOTAL LUMINOUS FLUX AND CHROMACITY MEASUREMENT FOR LED LUMINAIRES USING ABSOLUTE INTERATING SPHERE METHOD Pan, J. 1, Qian, F. 2, Min, F. 1 and Li, Y. 1 1 EVERFINE PHOTO-E-INFO., CO., LTD.,Hangzhou, China 2 Hangzhou Intitute of Calibation and Technical Supeviion, Hangzhou, China Abtact Thi pape peent an abolute integating phee (AIS) baed method fo convenient and accuate meauement of LED luminaie. The LED luminaie ae mounted on phee wall to be meaued in 2π geomet, a calibation fitting intoduce known amount of luminou flux into the phee though an opening to calibate the tem, and a efeence lamp i et in the phee. The coection fo the patial nonunifomit of phee epone. The meauement i compaed with a goniopectoaiomete. Kewod: LED luminaie, luminou flux, integating phee, abolute photomet 1. Intoduction LED luminaie ae diffeent fom taditional one in man apect, the hall be meaued and chaacteized in abolute photomet [1,2]. Both goniopectoadiomete and phee pectoadiomete can be applied fo total luminou flux and chomacit meauement of LED luminaie. [3] Goniopectoadiomete can achieve low uncetaint [3,4,5], but the cot i high and the opeation i time conuming. Integating phee tem have the advantage of low cot, pace aving, peed meauement and ea opeation. Howeve, b taditional ubtitution method, lage eo ma aie due to the diffeence between tet LED luminaie and efeence tandad fo calibation in apect of intenit ditibution, pecta, hape and ize, elf aboption effect, and etc.. To educe the eo, tandad lamp having diffeent intenit ditibution ma be pepaed o appl coection facto when uing omni-diectional tandad lamp. [3] Howeve, it i ve difficult to acquie o man tandad lamp with fine tabilit and epoducibilit. The Abolute Integating Sphee (AIS) method uing an extenal ouce [3,6] can achieve high accuac in man cae. But the method ha eldom been ued to meaue lage ized luminaie. The inteio phee pace i limited due to the cuent 4π geomet, and the lineait, heat accumulation and elf aboption ma contibute much to uncetaint. 2. INTEGRATING SPHERE GEOMETRY To olve the poblem and make the meauement of LED luminaie convenient and accuate, an abolute integating phee (AIS) baed method i developed. Fig.1 how the geomet of an integating phee deign fo thi pupoe. It conit of a main phee bod and a flat panel. It ha fine patial epone unifomit a no baffle o block taff in the main phee bod. The tet LED luminaie i mounted on the flat panel. The 2π meaument geomet i applicable fo mot LED luminaie a the onl emit light in fowad diection. The houing o fixtue can be et outide the phee. A hown in fig.1, the point on phee wall i
expeed in pola coodinate (θ,φ) with the oigin point i the cente of the flat panel whee tet luminaie i mounted, the diection oppoite to tet luminaie i defined a (0,0). On the flat panel and adjacent to the tet luminaie, thee i a calibation fitting and a mall ampling phee, and a efeence tempeatue-contant LED lamp. The fitting intoduce known amount of pectal adiant flux though an opening on fo calibation. It mainl compie a tandad pectal iadiance lamp and a hield optical pipe with pecie apetue. The opening fo calibation fitting can be coveed when it i emoved. A High Accuac Aa Spectomete (HAAS) i emploed fo meauement though the ampling phee. The efeence tempeatue-contant LED lamp ha good tabilit and epoducible, it i diectional and iadiate the aea aound point (0,0). The aangement minimie eo caued b patial nonunifomit and incident angle dependence of phee epone, and i convenient fo the calibation and meauement opeation. Figue 1. Geomet Scheme of AIS Method fo LED Luminaie Meauement 3. Calibation and meauement The efeence lamp i adopted to tanfe quantitie to make the meauement convenient. Fitl, calibate the efeence tempeatue-contant LED lamp againt the calibation fitting. The opening fo luminaie mounting i coveed with the ame inteio coating a othe pat in the phee. The pectal adiant flux intoduced into the phee Φ (λ) i given b: ( ) ( ) A (1) E Whee, E (λ) i the tandad pectal iadiance ove the limiting apetue of known aea A. The total luminou flux of the efeence LED lamp i obtained b: (2) Whee and ae eading to the efeence LED lamp and calibation fifing. Secondl, in outine meauement, the calibation fitting i emoved, and the tet LED luminaie i mounted. Compae the detecto eading to the efeence LED lamp and the tet LED luminaie, the luminou flux tet LED luminaie can be obtained b,
t t t (3) t t Whee t i the detecto eading fo tet LED luminaie, and t i the detecto eading fo efeence LED lamp which vaie with diffeent tet LED luminaie. The fit poce tanfe abolute quantit to the meauement tem, it need not opeated often. While the econd poce i a outine opeation that i necea fo each tet luminaie. The outine opeation i much moe convenient. The eo caued b elf aboption can be neglected. In the fit poce the efeence lamp emain in the phee when the extenal ouce i meaued, and in the econd poce the tet luminaie emain when the efeence lamp i meaued. The elf aboption effect ha been taken into account in the calibation. 4. Coection technique 4.1 Coection fo patial nonumifomit of phee epone The patial epone ditibution function (SRDF) K(θ,φ) and the nomalized SPDF K*(θ,φ) of the phee hall be meaued. In thi wok, a otatable beam ouce at oigin point i adopted to meaue the SPDF. Fig.2 i the SRDF K*(θ,φ) of a 1m integating phee a hown in fig.1. Figue 2. The SRDF of the AIS fo LED Luminaie Meauement The coection fo efeence lamp ae not necea, a the ae offet a eq. (3) how. The patial coection facto cf fo calibation fitting with epect to a fowad iotopic point ouce i calculate b the equation (4) to be 0.990. cf 1/ K (0,0) (4) The patial coection facto cf t fo tet LED luminaie with epect to a fowad iotopic point ouce i given b: 2 / 2 1/ I (, ) K (, )indd 0 0 cf t (5) Whee I*(θ,φ) i nomalized luminou intenit ditibution of tet luminaie. Ideall, the I*(θ,φ) i meaued b goniophotomete. Ideall, the I*(θ,φ) i meaued b goniophotomete. The cf t of tpical LED luminaie (ee table 2) i lited in table 1.
Table 1. cf Value of Tpical LED Luminaie Tpical LED luminaie C0 plane at φ=0 angle C0 plane at φ=90 angle PAR 30 0.985 0.983 Road light 0.992 0.988 Inteio light 0.988 0.985 Becaue the LED luminaie ha aniotopic light ditibution in C plane, the cf value ae diffeent when the C0 plane et at diffeent φ angle. Theefoe, otating the tet luminaie aound the diection (0,0) and take the detecto eading i an effective wa to check the influence caue b patial nonunifomit along φ diection. 4.2 Simplified method fo patial nonumifomit coection A implified method i popoed: calculated the cf value of vaiou tpical beam tpe, and toed them in oftwae; duing the meauement, opeato load pope cf value accoding to beam tle of tet LED luminae. So that the luminou intenit i not need. But poition of the tet luminaie hall be noticed, epeciall when it ha aniotopic ditibution in C plane. 5. Pactical meauement Diffeent kind of LED luminaie ae pacticall meaued. The meauement eult ae compaed with the output of a compact goniophotomete which equip a pectoadiomete [5]. Table 2. Compaion Between the AIS Method and a Goniophotomete Intenit AIS method Goniophotomete Beam angle ditibution cuve Φ(lm) CCT Φ(lm) CCT PAR 30 27.1 370.6 3455 379.98 3474 Road light 136.4 in C0/180 ; 52.3 in C90 /270. 2283.5 5850 2352.9 5870 Inteio light 85.8 906.2 4510 921.22 4529 6. Concluion An AIS baed method fo the meauement of LED luminaie ha been developed, and the meauement tem ha been etablihed a well. The meauement uing the AIS baed method ageed well with the compact goniophotomete, that the diffeence of total luminou
flux i within 3%. In thi method, the tandad pectal iadiance lamp i ea to obtain and can tanfe quantitie with high accuac, and the efeence tempeatue-contant LED lamp facilitate the calibation and meauement. The elf aboption coection i not necea, the eo caued b patial nonunifomit of phee epone i little due to the phee aangement, and it can alo be coected. A the AIS baed method fo LED luminaie ha convenient opeation, elative low cot and high accuac, it can be widel applied in indut fo epoductive meauement. Refeence: [1] IES LM-79-08 IES Appoved Method fo the Electical and Photometic Meauement of Solid-State Lighting Poduct. [2] GB/T 24824-2009 Meauement method of LED Module fo geneal lighting (Chinee national tandad). [3] Ohno, Y. and Zong, Y., 2004, Realization of the NIST Total Spectal Radiant Flux Scale, Simpoio de Metología. [4] Saute,,G.. 2008. Goniophotomet: New Challenge And Novel Solution, CIE X033. [5] Pan, J., Li, Q. and Max, P., 2009. The Ti-Field Goniophotomete, CIE Light & Lighting Confeence. Coeponding Autho: Jiangen Pan EVERFINE CO., LTD. #669 Binkang Road, Hangzhou, China Phone: +86-571-86698333 Fax: +86-571-86696445 E-mail: evefine@evefine.cn