無汞平面螢光燈之發光效率研究

Study of luminance efficiency in mercury-free flat fluorescent lamp

哀嘉華(Chia-Hua Ai)

指導教授 ： 黃振球

元智大學/工程學院/化學工程與材料科學學系/碩士(2009年)

摘要

本研究利用濕式轉印技術製作出含有不同厚度(100、200、300μm)螢光粉層、反射層(BaSO4)以及低功率材料(CsOH、CsCO3、CsWO4、CsI)之無汞平面螢光燈，並透過光學及電氣分析探討發光效率與其之關係。
從墊高放電區實驗結果得知，螢光粉層高度越高時會使其吸收紫外線之機率增加，尤其在表面電荷量較少時其效應越大，因此頻率40kHz時之發光效率增加幅度會較70kHz明顯。此外，在反射層實驗結果中得知，使用具有高介電常數(11.4)和高反射率(90%)的材料(BaSO4)作為平面螢光燈體中之反射層，其發光效率會隨頻率增加而增加，但當頻率超過60kHz時反而會因發光已達飽和狀態使得其發光效率增加幅度不大。而從低功率材料實驗之光電特性分析上得知，在低頻及低電壓時低功率材料影響效應會最大，反之在頻率越高其效應越不明顯，這是因為二次電子數量如果太多時會使燈體內有效碰撞降低，進而降低螢光粉層吸收真空紫外線(VUV)之機率；另外，在電氣分析上得知若燈體內螢光粉層表面上含有容易放出二次電子(Secondary Electrons)之低功率材料時，則會有助於湯生雪崩(Thomson Avalanche. Effect)效應之產生，此效應會降低平面螢光燈電壓進而提升其發光效率；此外，從老化測試結果可知燈體內添加低功率材料雖能提升亮度維持度，但對燈體色座標確會使其產生偏高現象(大約0.005~0.01之間) 。
最後，我們將上述三個實驗(墊高放電區、反射層、低功率材料)之最佳參數結合在最佳化實驗中分析得知，40kHz時其發光效率可提升14%左右，隨著頻率越高發光效率增益幅度越小，當頻率增加至70kHz時其發光效率僅提升3.7%左右。由此可知發光效率並不會因為實驗加成而成正比，反而會互相干涉。

關鍵字

平面螢光燈 ； 介電質放電 ； 二次電子

並列摘要

In this study, mercury-free flat fluorescent lamps use wet-transfer technology to manufacture the different thickness of phosphor (100,200,300μm), reflective layer (BaSO4) and the material of small work function layer (CsOH, CsCO3, CsWO4, CsI). Through the analysis of optical and electrical discuss the efficiency of their relationship.
As result experimentation of phosphors increase in discharge area, the higher phosphors thickness so that it will increase the chance of absorbing ultraviolet light, particularly in the surface charge less when the greater its effect, and therefore the range of efficiency increase of frequency in 40kHz is more obvious then 70kHz. In addition, the reflector layer in the experimental results that the use of the material (BaSO4) with high dielectric constant (11.4) and high reflectivity (90%) as the plane fluorescent reflector with its efficiency increase as the frequency increased, but the frequency over 60kHz it will have reached saturation point due to the range of its efficiency is slow down. By reason of the optical characteristics analysis about the material experimentation of small work function, effects of the impact will be greatest in the low-frequency and low-voltage, in contrast, the higher frequency of its effect is not obvious because the number of secondary electron if too many, when the effectively reduce the collision in the lamp body, and lower phosphor layer to absorb the vacuum ultraviolet (VUV) of probability. In addition, electrical analysis that if the lamp body on the surface layer off easily with secondary electron (Secondary Electrons) on the material of small work function, will contribute to Thomson Avalanche (Thomson Avalanche. Effect), the effect will reduce the voltage to enhance its efficiency in flat fluorescent lamps; then we can see the lamp with the material of small work function to enhance the efficiency of its luminous from the aging of testing results, but color coordinates of the lamp will occur to the higher color coordinates
(approximately between 0.01 to 0.005)
Finally, we will combine the best parameters of the above-mentioned (phosphors increase in discharge area, reflective layer, the material of small work function) in the best-informed analysis of the experiment, in 40 kHz the efficiency enhance about 14%, the efficiency gain the smaller the margin with more frequency, the increasing frequency to 70kHz only to enhance the efficiency about 3.7%. That proves the efficiency will not be in direct proportion experiment and the addition, it will interfere with each other.

並列關鍵字

Flat fluorescent lamp ； Dielectric barrier discharge ； Secondary electrons

參考文獻

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