[sdiy] SMD LED intensity and lenses

[Rutger Vlek]

Hi guys/girls,

I'm finishing up a new product that will contain a multi-color LED ring, which I plan to do with SMD leds in 4 different colors. In the prototype I had a hard time getting the intensities of the various colors of LEDs to match. I've now learned that not all manufacturers spec according to a comparable norm, so I've decided to stick with Kingbright components that at least have a reference to a uniform norm in their datasheets to make their reported intensities more or less comparable between colors and between leds. I can design in an option to regulate supply current to various colors individually, so technically I can compensate for any differences in intensity between leds.

However, now I'm considering which leds to start with and have options for 0603 leds with a dome lens or flat lens. There will be lightpipes in front of the leds to bring light to the front panel, so is there any advantage or disadvantage to the type of lens? And more importantly, will I run into issues if I combine leds with a dome lens from one color (and spec'd brightness) with other types of lenses? I suspect the lightpipes will straighten out a big portion of the leds angle of dispersion, but I'm still hesitant to mix and match, as I feel the resulting brightness at the end of the lightpipe may vary.

Any suggestions?

Regards,

Rutger

ps. LED rings are cool, as are bow ties.