scholarly journals Design and Simulation of Low Circadian Action Micro-LED Displays with Four Primary Colors

Crystals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 383
Author(s):  
Ziqian He ◽  
Guanjun Tan ◽  
Yi-Fen Lan ◽  
Shin-Tson Wu
Keyword(s):  
Circadian Rhythm ◽  
Light Emitting Diode ◽  
Liquid Crystal Displays ◽  
Real Image ◽  
Color Gamut ◽  
Daily Lives ◽  
Light Emitting ◽  
Primary Color ◽  
Long Time ◽  
Circadian Effect

Nowadays, displays are ubiquitous in our daily lives. Long-time exposure to a display’s unnatural light could influence the user’s circadian rhythm, especially at night. Here, we propose a four-color micro-light-emitting diode (LED) display to achieve low circadian action for nighttime uses. Specifically, we evaluate the RGBW-type (red, green, blue, and white) and RYGB-type (red, yellow, green, and blue) micro-LED displays in terms of circadian effect and color gamut coverage. With the addition of an extra white subpixel, it was found that the circadian effect at night can be reduced dramatically, but the color gamut remains unchanged. However, with an additional yellow subpixel, both the circadian effect and color gamut were found to improve. Finally, we simulated the circadian illuminance of real image contents for different displays. In comparison with existing liquid crystal displays, organic LED displays, and RGB (red, green, blue) micro-LED displays, the proposed four-primary-color micro-LED displays can significantly reduce the circadian effect at night.

scholarly journals Color-Enrichment Semiconductor Nanocrystals for Biorhythm-Friendly Backlighting

2018 ◽  
Vol 232 (9-11) ◽  
pp. 1457-1468 ◽  
Author(s):  
Talha Erdem ◽  
Hilmi Volkan Demir
Keyword(s):  
Circadian Rhythm ◽  
Light Emitting Diode ◽  
Semiconductor Nanocrystals ◽  
Emission Spectra ◽  
Green Emission ◽  
Color Gamut ◽  
Light Emitting ◽  
Human Circadian Rhythm ◽  
Led Backlight ◽  
Indoor Lighting

Abstract Nanocrystals (NCs) offer great opportunities for developing novel light-emitting devices possessing superior properties such as high quality indoor lighting, efficient outdoor lighting, and display backlighting with increased color definition. The narrow-band emission spectra of these materials also offer opportunities to protect the human daily biological rhythm against the adverse effects of display backlighting. For this purpose, here we address this problem using color converting NCs and analyzed the effect of the NC integrated color converting light-emitting diode (NC LED) backlight spectra on the human circadian rhythm. We employed the three existing models including the circadian light, the melanopic sensitivity function, and the circadian effect factor by simultaneously satisfying the National Television Standards Committee (NTSC) requirements. The results show that NC LED backlighting exhibits (i) 33% less disruption on the circadian cycle if the same color gamut of the commercially available YAG:Ce LED is targeted and (ii) 34% wider color gamut while causing 4.1% weaker disruption on the circadian rhythm compared to YAG:Ce LED backlight if the NTSC color gamut is fully reproduced. Furthermore, we found out that blue and green emission peaks have to be located at 465 with 30 nm bandwidth and at 535 nm with 20 nm bandwidth, respectively, for a circadian rhythm friendly design while the red component offers flexibility around the peak emission wavelength at 636 nm as opposed to the requirements of quality indoor lighting. These design considerations introduced as a new design perspective for the displays of future will help avoiding the disruption of the human circadian rhythm.

scholarly journals Remote-type, high-color gamut white light-emitting diode based on InP quantum dot color converters

2014 ◽  
Vol 4 (7) ◽  
pp. 1297 ◽  
Author(s):  
Sun-Hyoung Lee ◽  
Ki-Heon Lee ◽  
Jung-Ho Jo ◽  
Byoungnam Park ◽  
Yongwoo Kwon ◽  
...  
Keyword(s):  
Quantum Dot ◽  
White Light ◽  
Light Emitting Diode ◽  
Color Gamut ◽  
Light Emitting

Change of circadian effect with colour temperature and eye spectral transmittance at different ages

2020 ◽  
pp. 147715352092337 ◽  
Author(s):  
HJ Tian ◽  
T Chen ◽  
Y Hu ◽  
T Guan ◽  
MP Cai
Keyword(s):  
Pulse Width Modulation ◽  
Spectral Power ◽  
Light Emitting Diode ◽  
Age Groups ◽  
Spectral Transmittance ◽  
Potential Health ◽  
Light Emitting ◽  
Colour Temperature ◽  
Age Related ◽  
Circadian Effect

With the recent advances in photobiology research and light-emitting diode technology, considering the circadian effects and the potential health benefits of lighting has attracted much attention. In this work, to achieve a white light-emitting LED cluster with beneficial and tunable circadian effects, a red-green-blue-warm white colour-mixing method based on pulse width modulation has been introduced and developed. Five optimal spectral power distributions were achieved with the correlated colour temperatures of 2700, 4000, 5000, 6500 and 8000 K that provide maximum colour-rendering indices of 95.0, 96.6, 96.8, 95.6 and 93.5 for each correlated colour temperature. Moreover, the Bellia model was modified to take into account the reduction in spectral transmittance of the human eye that occurs with age. Using the five spectral power distributions, based on the eye spectral transmittance with age-related change, we studied the change of the circadian effect with corneal illuminance at the different correlated colour temperatures. Solutions are provided for scenarios where circadian effect should be avoided for different age groups while the reasonable illuminance and colour temperature are maintained.

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