4 ms·
I hate it when LED light output isn't continuous or visibly flickery, especially when it's from LED lights that are on (or are visible from) moving objects -- s
by zkms 9y ago
I hate it when LED light output isn't continuous or visibly flickery, especially when it's from LED lights that are on (or are visible from) moving objects -- such as LED taillights on automobiles or in-road lane lights. All the eye movement (or object movement) makes the flicker even more flagrant :(
I remember extremely flickery lane lights on the leftmost lane markers on California's infamous SR 110, on the northbound direction (towards Pasadena) in the tunnels (the ones right before the left-exit to I-5 north).
Good fluorescent bulbs will have electronic ballasts (the driving circuit) that supply current to the bulb with a higher frequency (in the low kilohertz) than the time response of the bulb's phosphor. Thus, any sort of flicker gets low-pass filtered and isn't significantly noticeable in the output light.
Even with a subpar magnetic ballast that drives the bulb with line frequency, the phosphor never gets close to fully extinguishing -- so there is flicker, but the instantaneous light output never gets less than, say, half the maximum instantaneous light output. Look on page 3 of http://www.usailighting.com/stuff/contentmgr/files/1/e18f88d078a54622682528e496596192/misc/flickerfactsheet_doe.pdf http://www.usailighting.com/stuff/contentmgr/files/1/e18f88d... for some instantaneous light vs time graphs for fluorescent bulbs.
LEDs have a much higher frequency response (in the tens of megahertz, easily) -- they respond quicker and more faithfully replicate their electrical drive signal as light output. You can see on page 4 of that report how violently jagged the LED's light/time plots can get.
If the manufacturer didn't want to include adequate filter capacitors in the LED's driver because of cost/reliability concerns, well, I hope your eyes enjoy that signal because the LED, unlike the fluorescent bulb, isn't going to smooth it out.
- perilunar 9y agoThose LED plots are pretty crazy. Surprising how much incandescent lights vary though (10-20% according to the plots) — would have it would have been much less than that.