Project 009 – Efficient production tester

Color Meter for White LEDs

This USB-powered color meter was built to easily and cost effectively sort individual white LEDs in a production environment. Back then, at this LED lighting manufacturer, the white LEDs used in the LED products would not all have the exact same color and it was necessary to sort them to give each customer batches of matched light outputs.

A spectrometer was deemed too expensive for this production environment, therefore RGB (red-green-blue) sensors were used with acceptable accuracy. This color meter was based on an earlier built RGB color meter for LED modules, so development costs were relatively low. The electronics was build around a Microchip PIC18F2550.

The LEDs would be manually placed by the operator onto a set of probes. Then by pressing the button, the computer would measure the color and determine in which output tray the LED should be placed.

The power supply for the LEDs was built into this device. Above the RGB color sensor there are two diffuse light mixing disks and an optical filter to block UV and IR light.

For similar solutions, please see also Project 008 and Project 010.