We report and demonstrate the feasibility of adapting glass as a phosphor-converted layer in laser headlight module, instead of conventional doped silicone that can potentially provide higher reliability and better performance for advanced laser headlight module. A laser headlight module (HLM) consists of blue a high-power laser array, a color phosphor, and an optical micro-lens system. The color phosphor is a key component in the HLM which consists of glass-based yellow phosphor-converted layer. The conversion layer of the yellow Ce:YAG phosphor is bonded on an aluminum substrate. A blue high-power laser array is used to excite the color phosphor and then release yellow light. Then, the combinations of blue and yellow light become white-laser light for use in the HLM. In this study, the fabrication of HLM with the glass-based yellow phosphor-converted layers is presented. The optical performance of the HLM including lumen, lumen efficiency, chromaticity, and transmission is detailed discussion. This study demonstrates the adapting glass as a phosphor-converted color phosphor in the HLMs that provide high-reliability and better performance for use in the new-generation laser headlight module.
A new scheme of high-reliability laser light engine (LLE) employing a novel glass-based phosphor-converted layer is proposed and demonstrated. The LLE module consists of a high-power blue light laser array and a color wheel, which includes two glass-based phosphor-converted layers of yellow Ce:YAG and green Ce:LuAG and a micro motor. The combinations of blue, yellow, and green lights produce high-purity phosphor-converted white-laser-diodes (PC-WLDs). The lumen degradation and chromaticity shift in the glass-based phosphor-converted layer under different laser powers are presented and compared with those of silicon-based PC-WLDs. The results showed that the glass based PC-WLDs exhibited in lower lumen loss and less chromaticity shifts than the silicon-based PC-WLDs. The long term reliability study evaluation in glass- and silicone-based PC-WLDs under high-power 120 W at room temperature for 20,000 hours is also presented and compared. The result showed that the silicone-based PC-WLDs exhibited 50% in lumen decay which failed in operation, while the glass-based PC-WLDs only exhibited 2% in lumen decay. This indicates that the proposed LLE modules are benefit to employ in the area where the silicone-based material fails to stand for long and strict reliability is highly required. This study demonstrates the advantages of adapting novel glass as a phosphor-converted color wheel in the LLE modules that provide unique high-reliability as well as better performance for use in the next-generation laser projector system.
A highly reliable laser light engine (LLE) employing a novel glass-based phosphor-converted layer is experimentally demonstrated. The LLE module consisted of a blue light laser array and a color wheel, which included two glass-based phosphor-converted layers of yellow YAG:Ce and green LuAG:Ce and a micro motor. The blue light laser array was used to excite the color wheel to create yellow and green lights. The combination of the blue, yellow, and green lights produced high-purity white light for use in LLEs. The glass-based LLE exhibited better thermal stability, higher luminous efficiency of 64.7lm/W(YAG:Ce) and 67.2lm/W (LuAG:Ce), and higher purity of 95.4%(YAG:Ce) and 77.4%(LuAG:Ce). This study clearly demonstrates the advantages of adapting novel glass as a phosphor-converted color wheel in LEL modules that provide higher reliability and better performance of laser projectors for use in the next generation LLEs, particularly in the area where the conventional LLEs employing silicone-based phosphor fails to stand for long and strict reliability is highly required.
The high-temperature operation up to 350°C of glass phosphor layer for using in converted white light-emitting diodes is
demonstrated. The results showed that the phosphor-converted white light-emitting diode (PC-WLEDs) maintained good
thermal stability in lumen, chromaticity, and transmittance characteristics at the high temperature up to 350°C. The
lumen degradation, chromaticity shift, and transmittance loss in glass based high-power PC-WLEDs under thermal aging
at 150, 250, 350, and 450°C are presented and compared with the silicone based high-power PC-WLEDs under thermal
aging at 150 and 250°C. The result clearly indicated that the glass based PC-WLEDs exhibited better thermal stability in
lumen degradation, chromaticity shift, and transmittance loss than the silicone based PC-WLEDs. The advantages of
glass doped encapsulation in high temperature PC-WLEDs could be arisen from the material property of glass transition
temperature 567°C higher than silicone of 150°C. These newly developed high-temperature glass based PC-WLEDs are
essentially critical to the application of LED modules in the area where the high-power, high-temperature, and absolute
reliability are required for use in the next-generation solid-state lighting.