Abstract
Dimming is critical to delivering the promise of solid-state lighting, but it needs to be implemented properly per the requirements of the application. Basic types of dimming, both analog and PWM, and their effect on LED characteristics are covered. Various methods of implementing fast and accurate PWM dimming are described. Phase-based dimming and the inherent complications associated with it are given some treatment, given its prominence in the market today, as is the 0–10 V dimming standard. The chapter then looks to the future and proposes various system-level architectures that support optimal intelligent lighting solutions. Trade-offs and considerations when selecting a communications infrastructure, including the physical layer, protocol, and application layer, are detailed.
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Abbreviations
- Analog dimming:
-
The act of dimming via reduction in average current level in the absence of PWM.
- Contrast ratio:
-
The minimum light intensity achievable by a dimming method with respect to the maximum or undimmed value, expressed as a ratio. For example, if a dimming method provides a way to achieve 0.1 % of full intensity, the contrast ratio would be 1,000:1.
- EMI:
-
Electromagnetic interference
- Flicker:
-
A catchall term for all light modulation, consistent or inconsistent in time, of any amplitude, visible or invisible. For further information, refer to Miller (2013).
- Flicker index and flicker percentage:
-
Terms used to express the extent and nature of light modulation. For more information, refer to Poplawski and Miller (2011).
- IGBT:
-
Insulated gate bipolar transistor
- LED driver:
-
The portion of system circuitry that processes power between the input source and the LEDs. LED drivers are also typically where a dimming command is translated to current, and hence light, modulation.
- MOSFET:
-
Metal oxide semiconductor field effect transistor
- PLC:
-
Power line communications
- PWM:
-
Pulse width modulation, a signal modulation technique that conforms the width of the signal pulse according to a pulsed input. It serves to decrease the average value of a signal proportional to the respective on and off times.
- Ripple:
-
Fluctuations in light that are (a) consistent over time and (b) less than 100 % in amplitude.
- RMS:
-
Root mean square
- SELV:
-
Safety extra low voltage
- Strobing:
-
Fluctuations in light that are (a) consistent over time and (b) typically 100 % in amplitude.
- TRIAC:
-
Triode for alternating current
References
Dyble M, Narendran N (2005) Impact of dimming white LEDs: chromaticity shifts due to different dimming methods. SPIE Proceedings 5941
Gu Y, Narendran N (2006) Spectral and luminous efficacy change of high-power LEDs under different dimming methods. In: Sixth international conference on solid state lighting, proceedings of SPIE 6337, 63370J
Miller Naomi (2013, Nov) Managing risks: Flicker. http://apps1.eere.energy.gov/buildings/publications/pdfs/ssl/miller_flicker_portland2013.pdf . Retrieved 5 Dec 2013
Poplawski M, Miller N (2011, Nov) Exploring flicker in SSL: what you might find, and how to deal with it. In: Paper presented at the ArchLED conference, Chicago. http://www.architecturalssl.com/sslinteractive/media/293/ArchLED%20flicker%20presentation.pdf. Retrieved 5 Dec 2013
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© 2015 Springer International Publishing Switzerland
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Denicholas, J. (2015). Dimming. In: Karlicek, R., Sun, CC., Zissis, G., Ma, R. (eds) Handbook of Advanced Lighting Technology. Springer, Cham. https://doi.org/10.1007/978-3-319-00295-8_21-1
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DOI: https://doi.org/10.1007/978-3-319-00295-8_21-1
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Publisher Name: Springer, Cham
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