In article <nnd$4d9a769b$61464ae6@e846562bf142425e>, Sjouke Burry <burrynulnulfour@ppllaanneett.nnll> wrote:>On 26.12.22 18:16, Ricky wrote: >> I know it costs more to make a more efficient LED bulb for room >lighting. Is there also a tradeoff between efficiency and operating >life? I can't think of a mechanism, but I'm not so familiar with LED >light bulb design. >> >Lots of light, high chip temp, shorter chip life.This can be offset by operating the leds vastly below capacity. E.g. I have a flash light costing 3.5 euro with 37 leds. I estimate that the leds have an effectively infinite life span. Unlike light bulbs you can diminish the current and have approximately proportional light. Groetjes Albert -- Don't praise the day before the evening. One swallow doesn't make spring. You must not say "hey" before you have crossed the bridge. Don't sell the hide of the bear until you shot it. Better one bird in the hand than ten in the air. First gain is a cat spinning. - the Wise from Antrim -
LED Bulb Efficiency vs. Operating Life
Started by ●December 26, 2022
Reply by ●January 19, 20232023-01-19
Reply by ●January 19, 20232023-01-19
On 19/01/2023 15:11, albert wrote:> In article <nnd$4d9a769b$61464ae6@e846562bf142425e>, > Sjouke Burry <burrynulnulfour@ppllaanneett.nnll> wrote: >> On 26.12.22 18:16, Ricky wrote: >>> I know it costs more to make a more efficient LED bulb for room >> lighting. Is there also a tradeoff between efficiency and operating >> life? I can't think of a mechanism, but I'm not so familiar with LED >> light bulb design. >>> >> Lots of light, high chip temp, shorter chip life. > > This can be offset by operating the leds vastly below capacity. > E.g. I have a flash light costing 3.5 euro with 37 leds. > I estimate that the leds have an effectively infinite life span. > Unlike light bulbs you can diminish the current and have approximately > proportional light.The catch is that if they are all in series with a current source or worse rectified mains then the first one to fail takes the entire chain out so MTBF is about 1/N th of the N components in the chain. I have seen some where there were ~60 white leds in series. Traffic lights seem to have about 4 chains that are independent so you don't get nice even illumination if one fails but they don't just stop completely one day like the old filament bulbs did. -- Regards, Martin Brown
Reply by ●January 19, 20232023-01-19
On 1/19/2023 10:37 AM, Martin Brown wrote:> On 19/01/2023 15:11, albert wrote: >> In article <nnd$4d9a769b$61464ae6@e846562bf142425e>, >> Sjouke Burry <burrynulnulfour@ppllaanneett.nnll> wrote: >>> On 26.12.22 18:16, Ricky wrote: >>>> I know it costs more to make a more efficient LED bulb for room >>> lighting. Is there also a tradeoff between efficiency and operating >>> life? I can't think of a mechanism, but I'm not so familiar with LED >>> light bulb design. >>>> >>> Lots of light, high chip temp, shorter chip life. >> >> This can be offset by operating the leds vastly below capacity. >> E.g. I have a flash light costing 3.5 euro with 37 leds. >> I estimate that the leds have an effectively infinite life span. >> Unlike light bulbs you can diminish the current and have approximately >> proportional light. > > The catch is that if they are all in series with a current source or > worse rectified mains then the first one to fail takes the entire chain > out so MTBF is about 1/N th of the N components in the chain. I have > seen some where there were ~60 white leds in series. > > Traffic lights seem to have about 4 chains that are independent so you > don't get nice even illumination if one fails but they don't just stop > completely one day like the old filament bulbs did.I guess one way to build a highly-reliable LED bulb might be to use LEDs manufactured with intrinsically high forward voltages, and then boost instead of buck the AC -> DC to maybe 400 volts, so you could eliminate the electrolytic cap also. Another thing I've seen is an IC with a switch matrix that monitors the line voltage and cuts series/parallel strings in and out in proportion to the instantaneous line voltage to keep illumination mostly constant
Reply by ●January 19, 20232023-01-19
albert wrote:> In article <nnd$4d9a769b$61464ae6@e846562bf142425e>, > Sjouke Burry <burrynulnulfour@ppllaanneett.nnll> wrote: >> On 26.12.22 18:16, Ricky wrote: >>> I know it costs more to make a more efficient LED bulb for room >> lighting. Is there also a tradeoff between efficiency and operating >> life? I can't think of a mechanism, but I'm not so familiar with LED >> light bulb design. >>> >> Lots of light, high chip temp, shorter chip life. > > This can be offset by operating the leds vastly below capacity. > E.g. I have a flash light costing 3.5 euro with 37 leds. > I estimate that the leds have an effectively infinite life span. > Unlike light bulbs you can diminish the current and have approximately > proportional light. > > Groetjes Albert >Depending on the construction of the lamp, there are a few things that cause LED output to degrade: 1. Darkening of the package material with time, heat, and optical dose. This is what's usually responsible for old optocouplers gradually failing. 2. Loss of fluorescent efficiency. This is slow for white LEDs, since the fluor is mostly inorganic Ce:YAG. 3. Propagation of dislocations into the active region, leading to lots of nonradiative recombination. 1 and 3 are thermally activated, and 3 is also caused by electromigration at very high current densities. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
Reply by ●January 19, 20232023-01-19
On Thu, 19 Jan 2023 15:37:17 +0000, Martin Brown <'''newspam'''@nonad.co.uk> wrote:>On 19/01/2023 15:11, albert wrote: >> In article <nnd$4d9a769b$61464ae6@e846562bf142425e>, >> Sjouke Burry <burrynulnulfour@ppllaanneett.nnll> wrote: >>> On 26.12.22 18:16, Ricky wrote: >>>> I know it costs more to make a more efficient LED bulb for room >>> lighting. Is there also a tradeoff between efficiency and operating >>> life? I can't think of a mechanism, but I'm not so familiar with LED >>> light bulb design. >>>> >>> Lots of light, high chip temp, shorter chip life. >> >> This can be offset by operating the leds vastly below capacity. >> E.g. I have a flash light costing 3.5 euro with 37 leds. >> I estimate that the leds have an effectively infinite life span. >> Unlike light bulbs you can diminish the current and have approximately >> proportional light. > >The catch is that if they are all in series with a current source or >worse rectified mains then the first one to fail takes the entire chain >out so MTBF is about 1/N th of the N components in the chain. I have >seen some where there were ~60 white leds in series. > >Traffic lights seem to have about 4 chains that are independent so you >don't get nice even illumination if one fails but they don't just stop >completely one day like the old filament bulbs did.Old traffic lights had special hi-rel, often dual-filament bulbs.
Reply by ●January 19, 20232023-01-19
On 12/27/2022 11:39 AM, John Larkin wrote:> On Tue, 27 Dec 2022 15:47:22 +0000, Martin Brown > <'''newspam'''@nonad.co.uk> wrote: > >> On 26/12/2022 17:16, Ricky wrote: >>> I know it costs more to make a more efficient LED bulb for room >>> lighting. Is there also a tradeoff between efficiency and operating >>> life? I can't think of a mechanism, but I'm not so familiar with LED >>> light bulb design. >> >> If you push the blue light flux and/or residual heating high enough it >> can damage/darken the phosphor used to generate the yellow light. >> >> The surface brightness of recent LEDs is now about the same per unit >> area as the sun - which makes it a bad idea to look directly at them. >> Blue, violet or UV ones especially. > > I have a 12-volt, roughly 1 cm square, array that looks like a welding > torch. It's the kind used in street lamps. > > Why don't they diffuse LED street lamps? They are annoying. >Especially when they start blinking
Reply by ●January 19, 20232023-01-19
On 12/28/2022 11:00 AM, John Larkin wrote:> On Wed, 28 Dec 2022 12:02:10 +0000, Clive Arthur > <clive@nowaytoday.co.uk> wrote: > >> On 28/12/2022 05:27, Jan Panteltje wrote: >>> On a sunny day (Tue, 27 Dec 2022 15:47:22 +0000) it happened Martin Brown >>> <'''newspam'''@nonad.co.uk> wrote in <tof42a$11vb$1@gioia.aioe.org>: >>> >>>> On 26/12/2022 17:16, Ricky wrote: >>>>> I know it costs more to make a more efficient LED bulb for room >>>>> lighting. Is there also a tradeoff between efficiency and operating >>>>> life? I can't think of a mechanism, but I'm not so familiar with LED >>>>> light bulb design. >>>> >>>> If you push the blue light flux and/or residual heating high enough it >>>> can damage/darken the phosphor used to generate the yellow light. >>>> >>>> The surface brightness of recent LEDs is now about the same per unit >>>> area as the sun - which makes it a bad idea to look directly at them. >>>> Blue, violet or UV ones especially. >>> >>> I have out tape over many LEDs on equipment I have, can still see those >>> through the tape. >>> It avoids blinding. >>> >> A place I worked once produced an instrument with a five digit >> seven-segment LED display. Because they were new and fashionable, blue >> LEDs were used. >> >> Every single one I saw in the field had Kapton tape over the display, >> which tamed it to a nice gentle dull orange. > > We used the Cree SiC blues when they were new. They needed 50 mA to be > visible. As time went on and blues got more efficient, our customers > started complaining. 1 mA is plenty now. > > We run test LEDs on a pc board at 100 uA now, so they don't blind you > when probing. >A regular-size red or amber common cathode 7 segment display, in series with a TL431 configured as a zener, and the segments driven from 5 volts looks just about perfect brightness to me! Seems stable with temperature, too.
Reply by ●January 19, 20232023-01-19
On Thursday, January 19, 2023 at 4:45:52 PM UTC-5, bitrex wrote:> On 12/27/2022 11:39 AM, John Larkin wrote: > > On Tue, 27 Dec 2022 15:47:22 +0000, Martin Brown > > <'''newspam'''@nonad.co.uk> wrote: > > > >> On 26/12/2022 17:16, Ricky wrote: > >>> I know it costs more to make a more efficient LED bulb for room > >>> lighting. Is there also a tradeoff between efficiency and operating > >>> life? I can't think of a mechanism, but I'm not so familiar with LED > >>> light bulb design. > >> > >> If you push the blue light flux and/or residual heating high enough it > >> can damage/darken the phosphor used to generate the yellow light. > >> > >> The surface brightness of recent LEDs is now about the same per unit > >> area as the sun - which makes it a bad idea to look directly at them. > >> Blue, violet or UV ones especially. > > > > I have a 12-volt, roughly 1 cm square, array that looks like a welding > > torch. It's the kind used in street lamps. > > > > Why don't they diffuse LED street lamps? They are annoying. > > > Especially when they start blinkingI can't stand the fast blinking LED tail lights on cars. Everytime I move my line of view, they create a dozen spots of light. When there are more than one it gets insane looking. Seems like most people don't even see this. The first time it happened to me I was trying to merge where there was no merge lane and the ramp was coming from an angle, rather than merging while driving parallel, so the rear view mirror didn't show anything useful. A quick look over my shoulder showed one car passing me, just as I needed to either go or stop. As I turned my head back, the tail lights (those tall Cadillac tail lights) suddenly blossomed into a dozen pairs of lights and I thought it was a bunch of cars! I had to hit my brakes to avoid an accident, only to find there was only the one car. Insane that they would create this sort of hazard, even if everyone doesn't see it. It's the sort of thing that would be changed on an airliner, after the first accident it causes. I've never found out how rapid the blinking is. -- Rick C. - Get 1,000 miles of free Supercharging - Tesla referral code - https://ts.la/richard11209
Reply by ●January 19, 20232023-01-19
On 1/19/2023 5:20 PM, Ricky wrote:> On Thursday, January 19, 2023 at 4:45:52 PM UTC-5, bitrex wrote: >> On 12/27/2022 11:39 AM, John Larkin wrote: >>> On Tue, 27 Dec 2022 15:47:22 +0000, Martin Brown >>> <'''newspam'''@nonad.co.uk> wrote: >>> >>>> On 26/12/2022 17:16, Ricky wrote: >>>>> I know it costs more to make a more efficient LED bulb for room >>>>> lighting. Is there also a tradeoff between efficiency and operating >>>>> life? I can't think of a mechanism, but I'm not so familiar with LED >>>>> light bulb design. >>>> >>>> If you push the blue light flux and/or residual heating high enough it >>>> can damage/darken the phosphor used to generate the yellow light. >>>> >>>> The surface brightness of recent LEDs is now about the same per unit >>>> area as the sun - which makes it a bad idea to look directly at them. >>>> Blue, violet or UV ones especially. >>> >>> I have a 12-volt, roughly 1 cm square, array that looks like a welding >>> torch. It's the kind used in street lamps. >>> >>> Why don't they diffuse LED street lamps? They are annoying. >>> >> Especially when they start blinking > > I can't stand the fast blinking LED tail lights on cars. Everytime I move my line of view, they create a dozen spots of light. When there are more than one it gets insane looking. Seems like most people don't even see this. The first time it happened to me I was trying to merge where there was no merge lane and the ramp was coming from an angle, rather than merging while driving parallel, so the rear view mirror didn't show anything useful. A quick look over my shoulder showed one car passing me, just as I needed to either go or stop. As I turned my head back, the tail lights (those tall Cadillac tail lights) suddenly blossomed into a dozen pairs of lights and I thought it was a bunch of cars! I had to hit my brakes to avoid an accident, only to find there was only the one car. Insane that they would create this sort of hazard, even if everyone doesn't see it. It's the sort of thing that would be changed on an airliner, after the first accident it causes. > > I've never found out how rapid the blinking is. >I usually see those flashing brake light mods on street racer-type cars around Providence RI, kids put them on their old Eclipse etc. to make them look cool. I don't know that they're much improvement over a regular high-level lamp at avoiding being rear-ended, though. There's some failure mode of LED street lamps and outdoor floodlights, etc. where the whole unit blinks at about 2 Hz.
Reply by ●January 19, 20232023-01-19
On Thu, 19 Jan 2023 16:51:10 -0500, bitrex <user@example.net> wrote:>On 12/28/2022 11:00 AM, John Larkin wrote: >> On Wed, 28 Dec 2022 12:02:10 +0000, Clive Arthur >> <clive@nowaytoday.co.uk> wrote: >> >>> On 28/12/2022 05:27, Jan Panteltje wrote: >>>> On a sunny day (Tue, 27 Dec 2022 15:47:22 +0000) it happened Martin Brown >>>> <'''newspam'''@nonad.co.uk> wrote in <tof42a$11vb$1@gioia.aioe.org>: >>>> >>>>> On 26/12/2022 17:16, Ricky wrote: >>>>>> I know it costs more to make a more efficient LED bulb for room >>>>>> lighting. Is there also a tradeoff between efficiency and operating >>>>>> life? I can't think of a mechanism, but I'm not so familiar with LED >>>>>> light bulb design. >>>>> >>>>> If you push the blue light flux and/or residual heating high enough it >>>>> can damage/darken the phosphor used to generate the yellow light. >>>>> >>>>> The surface brightness of recent LEDs is now about the same per unit >>>>> area as the sun - which makes it a bad idea to look directly at them. >>>>> Blue, violet or UV ones especially. >>>> >>>> I have out tape over many LEDs on equipment I have, can still see those >>>> through the tape. >>>> It avoids blinding. >>>> >>> A place I worked once produced an instrument with a five digit >>> seven-segment LED display. Because they were new and fashionable, blue >>> LEDs were used. >>> >>> Every single one I saw in the field had Kapton tape over the display, >>> which tamed it to a nice gentle dull orange. >> >> We used the Cree SiC blues when they were new. They needed 50 mA to be >> visible. As time went on and blues got more efficient, our customers >> started complaining. 1 mA is plenty now. >> >> We run test LEDs on a pc board at 100 uA now, so they don't blind you >> when probing. >> > >A regular-size red or amber common cathode 7 segment display, in series >with a TL431 configured as a zener, and the segments driven from 5 volts >looks just about perfect brightness to me! Seems stable with >temperature, too.We haven't used a 7-seg in ages. This is the last one, displaying a unit number from 0 to 7. LCDs are much better.
