What Is Binning?

Binning is the process of methodically sorting and grouping HB-LEDs according to some measured parameter or set of parameters. This allows design engineers to systematically specify an LED and it allows the manufacturer to order LEDs that function consistently like the specified part. Binning also makes it possible to re-order LEDs that match the original.

Why Is Binning Necessary?

The human eye can detect very subtle changes in color, down to ~10 nm for red and 2–3 nm for green. For white light LEDs, this sensitivity may or may not be an issue depending on the application. For example, in applications like flashlights and headlamps matching the exact chromaticity of white light is not as critical as that of an application using a string of a dozen or so HB-LED modules to light a wall in an office building.  If the LEDs aren’t matched properly, they will produce a kind of rainbow of different shades of white light on wall. This problem doesn’t exist with an incandescent lamp since it produces a wide range of frequencies. To minimize this potential problem, vendors provide binning charts.

Binning Process

Binning diagrams employ geometric regions on the CIE 1931 Diagram arranged along the BBL to specify chromaticity coordinate variation for specific The BBL in Figure 12 is the line on which the color temperatures for white light from sources with a CRI of 100 will lie. The lines labeled 5000K through 10000K are the lines of CCT. Each of the regions, such as WA, WB, and WC, represents two kinds of color variation. One is the CCT variation (for example, 5000K to 5700K in WH and WJ). The other variation is called tint, indicating how far the chromaticity coordinates are from the BBL. The top of region WG, for instance, would have a slightly more greenish tint than the bottom. The bottom of WP would have a slightly more purplish tint than the top. WD, in-between WG and WP, would have a smaller range of tint. Nevertheless, WG, WD, and WP are all in the same CCT range. Chromaticities that lie directly on the BBL do not have a tint.

 

Binning Chart Example: Cree Standard Cool White Regions

 

White Light Chromaticity Region

Regions, such as WE, are technically called chromaticity regions. The coordinates for the region are used to “bound” or define the region in terms of where it should be positioned on the CIE 1931 Chromaticity Chart. LED manufacturers publish tables of bounding coordinates for the regions they have defined.

Bounding Coordinates Table Example

 

Bin Code Example

Understanding how Bin Codes are created can be helpful when ordering LEDs. Correct formatting of the bin and order codes is described in each manufacturer’s Binning and Labeling Guide for the LED product series.