The bicycle laws in some states require bicycle lights be white. The eye sees yellow more efficiently than blue light. Blue light has been proven to damage eyes in excess quanities. I advocate moving away from the phosphorus coated blue or ultraviolet toward a yellow LED and a blue LED combination that is closer to incandescent spectrum. Ironically it is legal to drive with yellow fog lights only in foggy conditions. As a practical matter the technology has concentrated on the development of a single full spectrum LED. But yellow will catch up and will be far more efficent. As a cyclist I need only 1 watt. But there is no such thing as too much run time.
What is white?
- Thread starter zerodish
- Start date
PhotonWrangler
Flashaholic
I think any phosphor-white LED between 3000k - 5600k would pass muster as being "white." For cycling, the lower color temps are going to show the ground better, but higher color temps are more efficient and will thus appear brighter overall. Anything over 5600k is going to generate more glare, especially on wet roads.
Your use of states indicates US origin? if so, you can refer to your states lighting codes and look for some by-line along the lines of "promulgates regulation in accordance with cfr49 subsection 108," which will tell you that your state has incorporated the federal lighting regulations by reference. In laymens terms, if federally legal, it's good to go (probably).
Cutting to Cfr49, subsection 108, you'll find a color reference chart which tells you what is federally defined as "white" light. You'll see it's a pretty broad chunk of space, very similar to the charts used in LED binning and labeling documents to discuss variations in the tints available. Those further up and to the right in "white" led's will be considered white light sources, and you can get very warm color temperatures indeed.
You'll note there *is* a distinct gap between very warm white light, and what is considered "yellow" under federal law. But very warm white LEDs, especially if higher CRI should accomplish what you're looking for, even though they are less efficient than their cold white counterparts. LEDs have come a long, long way in the last 20 years, the least efficient high cri and warm color temp LEDs are still multiple times as efficient as the first several generations of high output white LEDs.
Here's a link to cfr49ss108, you'll need to scroll (and scroll and scroll) down to the reference tables section near the end of the page to find the chromaticity diagram
www.ecfr.gov
And here is a link to the diagram itself, hosted as an image (poor quality at that, but usable).
Cutting to Cfr49, subsection 108, you'll find a color reference chart which tells you what is federally defined as "white" light. You'll see it's a pretty broad chunk of space, very similar to the charts used in LED binning and labeling documents to discuss variations in the tints available. Those further up and to the right in "white" led's will be considered white light sources, and you can get very warm color temperatures indeed.
You'll note there *is* a distinct gap between very warm white light, and what is considered "yellow" under federal law. But very warm white LEDs, especially if higher CRI should accomplish what you're looking for, even though they are less efficient than their cold white counterparts. LEDs have come a long, long way in the last 20 years, the least efficient high cri and warm color temp LEDs are still multiple times as efficient as the first several generations of high output white LEDs.
Here's a link to cfr49ss108, you'll need to scroll (and scroll and scroll) down to the reference tables section near the end of the page to find the chromaticity diagram
Federal Register :: Request Access
www.ecfr.gov
And here is a link to the diagram itself, hosted as an image (poor quality at that, but usable).
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