LEDOLOGY

The future starts now

Currently, LED technology is the most efficient lighting technology. Thanks to the steady improvements in performance, we expect that this trend will continue moving forward at a fast pace. For many years, XAL has been integrating relevant development and production expertise into existing processes and is now able to offer mature, energy-efficient and sustainable products.

Various factors and evaluation systems are crucial for the qualification and description of LED products, such as binning. XAL uses exclusively LEDs with ANSI binning, which divides the color space around the black body line; the line along which the light points shine in pure white (CRI or Ra 100), into eight color points (between 7000K and 2600K).

The CIE diagram is a standardized color system defined by an international lighting commission, which covers the entire range of all radiant light colors. In this three-dimensional colour space every color is clearly defined with the coordinates x, y and z, and the sum of these is always one.

Using the LED spectrum, it is possible to represent the intensity of the wavelengths. If all of the wavelengths of the visible spectrum from 700-380nm are sufficiently present, the light source can reproduce all object colors. To do this, the corresponding color point on the BBL is compared with the test light source. The size of the binning field provides information on the color consistency of all of the LEDs used in this lamp. Sub-division of each of these 8 light color areas into 4 and 16 color points (for white-warm light colors < 4500 K) ensures optimum color homogeneity. The light quality of a lamp can be defined using homogeneity. Lamps which only use LEDs from a 1/16  binning currently meet the quality criteria 3-step SDCM (Standard Deviation of Color Matching) and are state-of-the-art.

Over their lifecycle, all light sources undergo a phenomenon called “color point shift” (CPS). For LEDs, this increases with the chip temperature and current strength. XAL tests the LEDs using the LM 80 test at different temperatures and current strengths and documents the results.

The only internationally valid evaluation of color rendering is the Color Rending Index Ra or Color Rendering Index CRI. In this process, using 15 test colors, the light source is compared with the corresponding reference color point, which has the same color temperature and lies on the black body line (BBL). The average value of the first 8 reference colors yields the color rendering index Ra and the CRI.

The Gamut Area Index (GAI)  is another possibility to evaluate the vibrancy of LED colors. The advantage in this regard is that the test light source can also be better than the reference light source. The color points of the 15 test colors in the reference light source are linked with each other in CIE 1976 and are compared with the test light source. The larger the Gamut Area is, the more vibrant the rendered colors appear.