Temperature compensation for LED filament standard lamps

LED light sources are replacing incandescent lamps gradually and inevitable, but using traditional incandescent lamps as standard lamps to measure LED light sources introduces greater uncertainty due to the great difference of their spectrum. In order to reduce the measurement uncertainty, a standard lamp based on LED filament is developed. The lamp is free of cumbersome cooling devices, and its luminous intensity distribution is uniform in 4π geometry. However, its luminous flux is sensitive to the ambient temperature. Therefore, a linear model of luminous flux as a function of ambient temperature and the lamp voltage is established. Then driven by a constant current, the lamp voltage, the relative luminous flux and the ambient temperature of the LED standard lamp are monitored. The model parameters can be obtained from the test data. Finally, by measuring the lamp voltage, the luminous flux drift caused by the ambient temperature can be compensated, so that the luminous flux of the LED standard lamp maintains a stable magnitude.