Author: Chan, Ka Yan
Title: Colour properties of LED lamp
Degree: M.Eng.
Year: 2012
Subject: Light emitting diodes.
Hong Kong Polytechnic University -- Dissertations
Department: Department of Building Services Engineering
Pages: viii, 70, [19] leaves : ill. (some col.) ; 30 cm.
Language: English
Abstract: In today's lighting industry, General Colour Rendering Index (CRI) 'Ra' published by the International Commission of Illumination (CIE) has been commonly used for over 40 years. However, there are concerns about the precision of ranking colour rendering since LED Lamp has been recently investigated. All test colour samples in CRI are biased to naturalness and thus penalize the light sources, including LED Lamps, which render the colour in a higher saturated way. Though Gamut Area (GA) is recommended to combine with CRI to support the representation of the vividness, it is not intelligible for consumers. Despite the fact that Full Spectrum Index (FSI) along with Full Spectrum Colour Index (FSCI) depend on the spectral power distribution only, it is not an energy efficient way to assess the light sources, especially mixed Red-Green-Blue lamps. Concerning these drawbacks, Colour Quality Scale (CQS) has been freshly developed to facilitate an ideal colour rendering index nowadays. However, though degree of saturation and correlated colour temperature have been considered in the calculations, current research with reference to CQS focuses on the numerical analysis and observers' feeling has not been taken into account. This study reviews the present colour rendering indices for the latest design of light sources and matches the indices to human sensation. Quantitative and qualitative examinations were separately executed. The calculated figures in different colour rendering indices were compared with the results of individual sensation test. This study shows the traditional colour rendering index CRI associated with GA and FSCI are not capable of human subject feeling. The outcome also shows that CQS is more applicable for all types of light sources together with LED Lamps than CRI in both subjective and objective aspects.
Rights: All rights reserved
Access: restricted access

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