Research on high luminous efficiency, high color rendering index chips on board light emitting diode and excitation and excitation saturation effect of phosphor

Abstract

A kind of chips on board (COB) package of light emitting diode (LED) light source is designed and produced. By reducing the current density and using the mirror aluminum substrate with high reflectivity to improve the luminous efficiency. Meanwhile, three kinds of red phosphors with peak wavelength of 630 nm, 631 nm and 639 nm are added on the basis of yellow‐green phosphors, which increase within the range of red light LED spectrum composition, improve the LED color rendering index. The measurement results show that under 500 mA forward current, the luminous flux density of LED on the luminous surface with an area of 227 mm2 reaches 14.4 lm/mm2, the luminous efficiency reaches 175.5 lm/W, and the color rendering index reaches 89.3. It is found in the process of measuring the LED color temperature changes slightly with the current change, and by calculating that the proportion of blue photons in the LED spectrum is increasing gradually, the cause of this phenomenon is the phosphor excitation efficiency is saturation when the optical power density is high, which is influenced in two aspects: the proportion of photons absorbed by phosphor or the phosphor excitation efficiency decreases, the two factors together or separately cause the phosphor excitation saturation effect.