發光二極體螢光粉塗佈層對色溫均勻性影響的研究

Abstract

高功率發光二極體產生白光的形式目前業界最普遍的作法是利用藍光晶片搭配黃色螢光粉，透過螢光粉量的調整經由藍光與黃光的混色產生不同色溫之白光，螢光粉的封裝技術會影響螢光粉在封裝體內的分布情況，當變角度的色溫落差越大時，則容易使產品產生光斑，導致顏色與亮度的不均勻，主因在於晶片周圍的螢光粉分布狀況可能影響其變角度的藍黃光混色不一致，引發所謂的藍圈或黃圈現象，這也是目前直接被要求改善的項目。 本論文主要探討發光二極體螢光粉塗佈層對色溫均勻性的影響，對於變角度色溫落差的可能因素，藉由不同正側光比例的發光二極體晶粒搭配不同螢光粉量的噴塗配比與塗佈層的實驗，使晶片周圍的螢光粉層有較適分布，並對於晶片正面螢光粉層的厚度與變角度色溫均勻性關係進行探討，以及晶片側壁的螢光粉層包覆性影響變角度色溫均勻性的觀察，也針對不同尺寸晶片的正側出光相對比例進行量測，並藉由同一封裝體輸入不同電流的實驗，探討變電流對變角度色溫均勻性的影響，最後比較螢光粉塗佈層對色溫均勻性的結果，期望在光品質的提升上有所貢獻。

The most common industry method for producing a form in which high-power light-emitting diodes (LEDs) generate white light is to combine blue light chips with yellow phosphor or fluorescent powder. By adjusting the amount of fluorescent powder, white lights with varying color temperatures are produced through a mixture of blue and yellow light. The fluorescent powder encapsulation technology affects the distribution of fluorescent powder within the capsule. If the difference in color temperatures of the variable angle is larger, flares can easily result in products, leading to uneven distributions of color and brightness. This is primarily because the fluorescent powder distribution around the chip may cause inconsistencies of the blue-yellow-light mixture of the variable angle, resulting in so-called blue-circle or yellow-circle effects, which are items currently requiring improvement. In this study, we primarily investigated the effects that LED fluorescent powder coating have on the uniformity of color temperature. Regarding the possible factors causing color temperature differences of the variable angle, varying proportions of direct- or front-lit and edge-lit LED grains coated with differing amounts of fluorescent powder spray coating mixture ratios and coating layers were employed for experimentation. This was done so that the fluorescent powder layer around the chip was more appropriately distributed. The relationship between the thickness of the fluorescent powder layer on the front facade and the uniformity of the color temperature of the variable angle was examined. The influence that the fluorescent powder layer encapsulation or coverage applied to the sides of the chip had on the color temperature uniformity of the variable angle was observed. Additionally, the relative proportion of lights emitted from the front facade and sides for chips of various sizes were measured. Furthermore, different electrical currents were input to the same capsule to examine the effects of various currents on the color temperature uniformity of the variable angle. Finally, the resulting effects of the fluorescent powder coating layer on the uniformity of color temperature were compared under the expectations that the findings of this study can improve the light quality.