Energy-conscious facility designs strive to include natural daylight in workspaces. However, the correlated colour temperature (CCT) and spectral content of daylight varies throughout the day while existent electric lamps produce light with a fixed CCT, resulting in mixed-illumination environments. A prototype LED lamp, with a simple control concept and a novel pulse-width modulation drive circuit, is proposed. This white light over a broad range of CCT values while maintaining a stable colour quality fidelity score with respect to a standard daylight source having an equivalent CCT. This range of CCTs is obtained without requiring computations for spectral approximation, resulting in a simplified control system.
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