Abstract:For a group of commercially obtained LED filaments without screening, the difference of total luminous flux is 7% and the difference of voltage is 0.6% . If the filament is directly used to make standard lamps without screening, it will not achieve the expected luminous intensity spatial distribution, the lamp stability and rated life will be reduced also. A screening method for LED filament has been prosed based on a series experiment, the voltage and luminous flux correlation between low driven current and rated driven current is analyzed. It shows that if 5 mA is used to instead of the rated driven current 10 mA for screening, the maximum deviations of voltage and luminous flux are 0.09% and 0.65%, respectively, which can meet the screening needs. The developed screening method and related software make the screening process fast to operate, accurate and reliable to determine the results, and does not reduce the rated life of the filament. This has laid a good foundation for the development of total luminous flux standard lamp using LED filament, that can also be applied to quality control in the production process of LED filament.
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