LED Tape for Tunable White Based on an Inductive Design
LED modules providing tuneable white is the core technology for human centric lighting. It is state of the art that such LED modules consists of two types of LEDs with different color temperatures. These two groups of LEDs are supplied independently and thus a variable color temperature based on the mixtures of the emitted light of the two types of LEDs is resulting. For many applications a flexible circuit tape offers interesting advantages when used for human centric lighting: Such a LED-tape can be easily customized to any required length and can be bended within a large extend.
The limitations of this technology are linked with the layout of the flexible circuit tape and the output characteristics of an external controller providing constant supply voltage for the LEDs.
We are now presenting a new technology how to design and operate a flexible circuit tape for tunable white applications: Core of our design is that we are suppling single LEDs by an inductive coupling which is a part of the flexible circuit tape design. By adjusting the frequency of the power line we can control the emitted light of such a single LED. Thus, it is possible to have different lumen output of different LEDs when the frequency of the powerline is tuned. Moreover, it also possible to use three groups of LEDs with different color temperature in order to improve the color quality of tuneable white. No additional wiring is required. It is only a matter of controlling the frequency of the power line.
In our paper we show the principles of this technology and give hints for the design. We are discussing the parameters which are essential for operating such a flexible LED-tape. Additionally, we give ideas where this technology can be used. We also present our vision how this principle can be further improved.