Elimination of Binning and Enhanced CCT Control

Sep 15, 2009

By Dr Gareth Jones, Chief Technology Officer, ENFIS

The emergence of the white LED has led to great promise in the reduction of energy associated with lighting. However, many lighting tasks require a quality of light (known as CRI) which had not been achievable with single white LEDs. By adding different colours of light together it is possible to create LED light sources with very high quality (high CRI) which are suitable for even the most stringent lighting tasks. In addition by changing the relative proportion of the colours of light one can create any white colour with very high CRI, known as vari-CCT.

Enfis has developed a patented vari-CCT technology that enables tuneable white light of very high CRI guaranteed to be controlled to within tight CCT limits.

As white LEDs make their way into the general illumination market, color consistency becomes critical for acceptance. For example, the color of white light can vary greatly, from a warm yellow-white to a cool blue-white. Most phosphor-based, high-power white LEDs on the market today show significant color variations from one white LED to another. In side-by-side applications, such as wall washers, cove lights or other LED luminaire applications, this color variation can be highly noticeable and very unpleasant. Thus, there are the following key unique attributes to Enfis smart multi-chip array light engines:

• Multi-chip platform with phosphor on chip technology integrated with saturated colors
• Binning issues solved by the use of multi-chip technology with Smart Array control allowing a wider range of LED chip specifications cutting the cost of materials for the LED light source
• Smart Color Control and Smart Driver electronics designed specifically for Enfis arrays which has calibration data necessary to ensure that the CCT you want is the one you get every time
• Efficient optics giving excellent color mixing and beam angles from 9degrees tight spot through spot and flood to wide flood angles at > 60 degrees.
  

By utilizing the multi-channel approach and smart electronics, Enfis is able to offer tuning of the color temperature, vari-CCT, across the whole white light locus, even into the very warm white region below 2800K with high Color Quality (Ra>90). With the Enfis CCT-lock capability each color temperature selected can be controlled to within 100K.

Multi-Chip Technology

Enfis arrays have 4- channels which can be independently adjusted to control colour to a very high degree of specification. Enfis UNO-PLUS and QUATTRO-MINI arrays are shown below.

Each array mixes the color within a small area in quad (2z2) formation to ensure that good color mixing can be achieved when projecting the light onto the lighting target zone. The color mixed in a manner shown below:

Binning Issues Resolved

The creation of white light by traditional blue chip + phosphor solutions leads to a large distribution of white color temperatures which are produced by normal manufacturing processes given variations in phosphor composition, thickness and blue LED wavelength. This is shown by the rectangle featured in the center of the color space diagram on the right hand side of the Fig. 4.

Enfis color mix technology can utilize wide bins of starting colors but through the use of its SMART ARRAY and DRIVER technologies and factory auto-calibration a precise and stable Color Temperature can be selected and “locked-in” for the lifetime of the luminaire, as shown in the left hand side of the diagram below.

Smart Control/Smart Driver

Figure 5 shows a comparison between a traditional current controlled driver and the ENFIS SMART close loop light controlled drivers.

As can be seen the traditional driver will lead to a reduction in lumens and a considerable change in the color temperature over the lifetime of the luminaire, whereas the Enfis driver which responds to the changes in the efficiency of each colour with time will give the same colour temperature and lumens at the start of life as it will at the end of life. The use of the patent SMART ARRAY optical feedback technology will also lead to greater stability of the color and lumens with changes in the temperature of the systems as shown in a real measurement (Fig. 6).

The driver electronics have in-built DMX/RDM and RS-232 communications capability to enable it to work effectively on the network.

Efficient Optics

Many multi-colored LED systems suffer from color aberrations and colour separation caused by the optical sources being separated apart. The Enfis Multi-chip Array has ultra-compact chip packaging with quad colour mixing to ensure minimal colour source separation leading to use in mixing the colours in any subsequent optical systems. Enfis optical systems rely on efficient and low-cost reflector technologies- see below to enable scalability, narrow and wide beam profiles and excellent beam shape and colour mixing profiles.

For more information of Enfis LED Array, Light Engines, Drivers and Optics please go to www.enfis.com
Tags: