A phosphor converted RED light for automotive LED rear lamp and compliance with ECE light regulation

Abstract

In conventional red color lighting LED lamp for vehicles are composed of red color lighting LED and additional transparent or red lenses. Generally red color lighting LED is based on the semiconductor materials as AlGaInP, AlGaAs or GaAsP. Such RED LEDs are mostly affected by temperature. As the temperature increases, the luminous flux droops sharply and lighting efficiency decreases accordingly. In addition, the light color changes due to the wavelength shift phenomenon. This makes the design for automotive ECE regulation for red light very demanding. In this study, it is intended to develop a high-efficiency RED LED light for automobile rear lamps with the phosphor-converted LEDs technology used the characteristics of blue light LED. The luminous flux droop affected by temperature change which is the most important parameter in vehicle lamp performance, is measured, and the compliance with the red light ECE regulation for automobiles is compared and evaluated. For measuring the optical properties, it was performed using the T3Ster TeraLED system. The PC RED LED chips for new development used blue LED based on InGaN (455 nm) and conventional RED LED chips are AllnGaP LEDs (614 nm, 620 nm). To optimize optical properties of PC RED LED, phosphor was applied in 5 grades according to concentration. The best optical properties of PC RED LED shows at the phosphor concentration of 40 %. The results have important implications for improving the performance of automotive red lamps.