Talk:Light-emitting diode/Archive 4

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Pulsed LEDs

The article talks about pulsed LEDs in the context of dual brightness systems:

"In a dual intensity circuit (i.e., rear markers and brakes) if the LEDs are not pulsed at a fast enough frequency, they can create a phantom array, where ghost images of the LED will appear if the eyes quickly scan across the array."

However, LEDs are visibly pulsed in many situations where there appears to be no obvious reason. For example, the turn signal indicator on cars where there is no dimmed option (or requirement). Brake lights in the same application where they are separated out from the tail light cluster (and the tail light cluster is pulsed as well). Front mounted side lights on cars. Traffic lights (some dim at night but the lights are still pulsed during the day). The list goes on. Any ideas anyone? DieSwartzPunkt (talk) 18:10, 23 November 2011 (UTC)

I'm not sure what you're actual question is - but the quoted line refers to the stroboscope effect. There's no such effect - to the human eye - for low frequencies ("visibly pulsed" qualifies)and therefore no issue. --77.8.233.229 (talk) 13:46, 27 November 2011 (UTC)
“There's no such effect”!! Maybe for your eyes. Not mine, I can see this on many cars with LED lit taillights, especially when the eye is glancing from one object to another. On a few occasions, I have been following behind a car that had very bright taillights running at a frequency so low that I could see it continuously, without averted gaze. I would get a strong headache/eyeache within a minute. Very annoying.
76.6.164.233 (talk) 13:18, 24 March 2013 (UTC)
My question is: why go to the trouble? Why bother including a complication to cause the LEDs to flash when a simple resistor that will give a continuous light output will do an equally good job (as far as the eye can perceive at least). Now knowing how car manufacturers penny pinch at the slightest excuse, they must have a very good reason for including an apparently redundent flasher circuit. DieSwartzPunkt (talk) 19:15, 5 December 2011 (UTC)
Are you talking about Pulse width modulation? If you want to run, say, a 10 watt LED at half brightness, if you're using a linear resistor you must dissipate about 5 watts in the external resistor so that the LED only gets 5 watts. Or, you can use a switch which dissipates almost no power, and duty-cycle the LED at 50% on time so as to appear half-bright. Sometimes a switch that dissipates no power is cheaper than a relatively high-powered resistor. You have to do the PWM at a frequency high enough to avoid visible annoying "strobe" effects. --Wtshymanski (talk) 19:36, 5 December 2011 (UTC)
I follow your point, and I was aware of this. However, my fundamental point remains: what car manufacturer is going to install a PWM when a simple resistor is a much cheaper option? The difference in power consumption is hardly a problem in this application being, as it is, less than a watt ot two.
I have just erected my Christmas tree for this year and decced it out with LED lights. These flash as well (very rapidly). Why? What's the point? The LEDs connected in series/parallel can easily be run from the 24 volt power supply without any series resistor at all. DieSwartzPunkt (talk) 12:05, 11 December 2011 (UTC)
PWM is typically used when a variation in the light output is needed. It is rather more complicated to control the light output using the voltage then the current. --Thorseth (talk) 09:10, 12 December 2011 (UTC)
I understand that point. But in both the applications I have mentioned, there is no requirement (or provision) for dimming the light output. DieSwartzPunkt (talk) 16:33, 12 December 2011 (UTC)

There is an effect that I read about 30-40 years ago. Multiplexed LED displays are brighter in appearance than they would be if driven staticly: In other words, drive an LED with 100 milliamp rapidly pulsed (say, over 100 hz), 10% duty cycle, and it will appear brighter than the same LED driven with 10 milliamp driven continuously. A small portion of this effect is that LEDs are more efficent driven at higher current levels, but most of this is related to the sensitivity of the (human) eye. Jamesdbell8 (talk) 16:00, 14 July 2012 (UTC)

I remember reading somewhere that an LED is at its brightest during the first few micro or milliseconds after it is turned on, which is why the high frequency PWM DC driving circuit is used, providing more light for less total Amps.
(Thus presumably allowing the car manufacturer to make a cost saving by fitting smaller cables to the light fittings in the vehicle. Having more copper wire in a vehicle can be more expensive than having more (incredibly cheap Chinese) microcircuits.)
This is quite important to the "Considerations for use": `Power sources' section. If anyone has more information on this, please add it to the article or possibly put a link to a site with the data. Thanks. Darkman101 (talk) 19:49, 19 September 2012 (UTC)
I added a little about pulsed operation to LED circuit#Pulsed LED operation. I agree that many people think that pulsing LEDs somehow makes them brighter or seem brighter, but I suspect that is an urban legend, caused by a misunderstanding of the *other* reasons people pulse LEDs. --DavidCary (talk) 00:32, 28 December 2012 (UTC)
Certainly for white LEDs, it's no longer the case that brightest operation (i.e. a pulsed current greater than the largest constantly sustainable current) uses pulsed drives. This may still need updating or expanding. Andy Dingley (talk) 00:47, 28 December 2012 (UTC)
I worked with high power LED's in the last years and I developed a power supply which deliver directly the required amount of current needed for the LED for a certain luminosity, without using PWM for. The source itself is a PWM power supply, but delivers DC to the LED. The LED is more efficient when used at lower currents than maximum, because of the droop effect. Also the heating is smaller. Combined, these two have a greater effect on efficacy, the LED (CXA2011) works at typically 70 lm/W at full power but is around 100lm/Watt at 1/3 of the power. The efficacy data curves can be found on most reputed producers on datasheets. — Preceding unsigned comment added by 41.67.136.106 (talk) 23:31, 16 December 2014 (UTC)

"First LED" diagram and tunnel diode

US Patent 3,293,513 ( column 7, around lines 60-65) expressly states that tunneling is not desired in an (infrared) LED and that the device doesn't have the concentration of donor atoms to make tunneling possible. SO, I took the word "tunnel" out of the caption. It's not clear to me what the relationship was meant to be between "tunnel diode" and "LED" - some older versions of the article talked about taking certain techniques from tunnel diode manufacture for LEDs, but this doesn't seem particularly fundamental to understanding the LED. --Wtshymanski (talk) 17:14, 7 January 2015 (UTC)

Quantum Dots

This technology has been commercialized, and is no longer "experimental", in the form of plastic sheets or films. QD Vision received a technology award (http://sid.org/About/Awards/DisplayIndustryAwards.aspx). The QD film is used in Sony LCD TVs (with the TRILUMINOUS trademark) since 2013, and more recently, Amazon Fire tablet computers. The film converts blue light from LEDs into red and green, to provide the RGB emmisions in balance to achieve the desired white-point (e.g. 6503 K). Rich S 10001 (talk) 18:47, 5 October 2014 (UTC)

Thanks, I fixed the heading but the text might need some more love. I see a reference from 2008 in there, that is probably not relevant anymoreThorseth (talk) 14:38, 6 April 2015 (UTC)

Anachronism - History

Under the History heading, Discoveries and early devices subheading, fourth paragraph, is the following sequence: "In the fall of 1965, while working at Texas Instruments Inc. in Dallas, TX, James R. Biard and Gary Pittman found that gallium arsenide (GaAs) emitted infrared light when electric current was applied. On August 8, 1962, Biard and Pittman filed a patent titled "Semiconductor Radiant Diode" based on their findings..."

So, they filed a patent three years before making their discovery? That feat is far more noteworthy than the invention of the LED!108.13.99.101 (talk) 04:27, 15 June 2015 (UTC)

Is the bus sign LED or plasma?

The photo isn't sharp enough to tell for sure but from the orange color, the bus sign looks more like plasma than LED to me. Anyone know for sure? Unless we can be sure, I don't think it belongs in this article. Msnicki (talk) 02:47, 14 September 2015 (UTC)

The image description page says it's LED, but unless the uploading user is in the bus manufacturing or maintenance industry, I'm inclined to agree with you that we can't know. I've removed it for now; here's the wikicode if this dialogue goes in the direction of reintroducing it to the gallery:
| File:LED bus destination displays.jpg | LED destination signs on buses, one with a colored route number
@Arriva436: It's your image. Care to weigh in? – voidxor 19:02, 14 September 2015 (UTC)

A/an LED

Since I started watching this page 2-3 months ago, I've noticed that several different people have mistakenly changed "an LED" to "a LED", presumably mispronouncing the name. I was just about to insert an HTML comment near the first mention of "an LED" noting its correct usage, but since it appears many times throughout the considerable-length article that's unlikely to be effective. Instead, I propose we create Template:Editnotices/Page/Light-emitting diode (i.e. an edit notice which will appear when editing the article) with a brief but fairly visible note explaining why "an LED" is correct. Any thoughts on this? GiftigerWunsch [TALK] 22:52, 26 October 2010 (UTC)

Why does everyone on this talk page seem to be unable to understand the fact that "LED" is very commonly pronounced as "led", in the same manner that NASA, NATO and ASAP are pronounced as words rather than acronyms? "Scuba", "laser" and "radar" all originated from acronyms. I'm not directing this at anyone, I'm just saying, it really doesn't matter. Sorry to rant, but let me respond to the matter at hand: I don't thing Giftiger's suggestion is necessary. Why? Because people can't read IPA pronunciations (another thing Wikipedians seem to have a hard time grasping :P) I'm just going to include a correct pronunciation that normal people can understand: "L-E-D". Swarm X 11:54, 4 December 2010 (UTC)
No. No it's not pronounced "led" (added to my comment). GiftigerWunsch [TALK] 11:59, 4 December 2010 (UTC)
No what's not? Swarm X 14:25, 4 December 2010 (UTC)
Oh, it's not pronounced "led". While you're correct on that count and I'm well aware of the fact that doesn't change anything of what I said. If my response to your actual section was clouded by my ranting, let me clarify:
  • Many people pronounce "LED" as "led" (as is common with acronyms). Though the article contains the correct pronunciation, it's in IPA, which few know how to read, therefore, they continue editing the article thinking "led" is the correct pronunciation. A simple solution to this problem would be to add a pronunciation that people actually know how to read (!). Hence me doing so. Problem solved? We'll see. Swarm X 01:01, 5 December 2010 (UTC)
While you have a point about the IPA pronounciation, I'm not convinced this'll make a difference to the a/an thing. It's only an intermittent issue though so it's not a huge problem. GiftigerWunsch [TALK] 01:04, 5 December 2010 (UTC)
I don't really think people believe "a L" to be correct, as opposed "an L". I'm under the impression that a large part of this happens because of people who think "a 'led'" is the correct pronunciation, rather than "an L-E-D" (which is technically correct). Swarm X 02:08, 5 December 2010 (UTC)

WHAT? Does anyone here even know basic english??? The prefix "an" is ONLY used when the proceeding word starts with a vowel. Some example are: an apple NOT a apple, an orange NOT a orange, a car NOT an car, a led NOT an led. If it starts with A,E,I,O,U, then you use "an", otherwise it a prefixed with just "a". The correct usage of l.e.d (spelling out the letters if you desire to say it that way) or led (say: lead (rythming with head, bed, said, etc.) are the correct usage terms.

It is pronounced [led], as shown here and here (use the sound). It is impractical to read it l. e. d., the "an" camp is fighting a loosing battle. Doru001 (talk) 13:35, 12 January 2016 (UTC)

It is NEVER "an LED". — Preceding unsigned comment added by 115.70.80.179 (talk • contribs)

You use an if the pronounciation starts with a vowel sound. LED is pronounced "el ee dee", so it is an LED, and not "a LED". GiftigerWunsch [TALK] 00:01, 6 January 2011 (UTC)
Note also that LED is never pronounced as a word like "lead", it's spoken as its individual letters. GiftigerWunsch [TALK] 00:04, 6 January 2011 (UTC)
'Does anyone here even know basic english???' 'The prefix "an" is ONLY used when the proceeding word starts with a vowel.'
An historic event. Giftiger wunsch is correct and the guy above him must not know basic english.

I just added both pronunciations to the article; not sure how that affects this rather crunchy discussion. I think both an elly-dee (individual letter names; UV LED rhymes) and a led (as a word; red LED rhymes) are both widely used pronunciations. But pronunciation as lede is incorrect and therefore the ambiguous lead should be avoided. However it is pronunced in the Wikipedia article, it should be done consistently. As for adding special hacks so that editors will see the rule, why not simply add it to the article so that all readers see it? Something like “LED, pronunced elly-dee or led, the first/second being used in this article”. Vadmium (talk) 06:53, 22 June 2011 (UTC).

But it's through ignorance that people say led (like red) so should it not explicitly say that it is pronounced as individual letters so that people don't think it's in any way correct to pronounce it wrong. The only people that are getting bothered are those that are in the habbit of calling them led (red) and refuse to admit they are wrong and get on with it. Hasn't someone already mentioned that the dictionary states it is L-E-D. — Preceding unsigned comment added by 79.70.109.179 (talk) 17:32, 22 June 2011 (UTC)

I'm afraid that this is one of those British/American English things. Those people who have pointed out that in English 'an' only ever precedes a word that actually starts in a vowel are entirely correct. Thus 'an history' is actually wrong (this seems to have come about as a form of snobbery by people who know that the original French word of pronounced 'otel'). Equally if you accept 'led' as a word then it is 'a led'.

Unfortunately, the Americans haven't used English for nearly two and a half centuries, and have adopted many rules (and spellings) of their own - largely through laziness at learning anything remotely complex. Thus the Americans will add an 'an' to any word whose pronounciation starts with a vowel. Thus they may say 'a led', but will incorrectly say 'an ell-ee-dee'.

Wikipedia's style guide cuts straight through the problem and although it requires that the English used throughout an article is consistently British or American, it does state that the use of 'a' or 'an' depends on the pronounciation (i.e. the American system). DieSwartzPunkt (talk) 18:23, 23 November 2011 (UTC)

Are you seriously saying that "a hour" is correct opposed to "an hour"? It's not snobbery - you're just wrong. You seem to suggest that it's Americans that have added 'an' before words that start with a vowel sound, but ask any native British English speaker. They will tell you it's "an hour" because the word starts with a vowel sound. — Preceding unsigned comment added by 89.238.164.18 (talk) 17:02, 18 March 2013 (UTC)
Wow, what a discussion! It is most certainly an LED, and an hour. LED should definitely be pronounced ell-ee-dee. I just asked a couple of electronics hobbyists these questions, and it was as obvious to them as it was to me which was correct.
“I have desoldered an LED for you” vs “I have desoldered a LED for you”
“I will be back in an hour” vs “I will be back in a hour”
However, this would be misuse of an: “I have desoldered an single LED for you.” See how different “wrong” sounds?
BTW, I saw the word “pronounciation” appear above; the correct spelling is “pronunciation.” Oh well.
76.6.164.233 (talk) 13:29, 24 March 2013 (UTC)
This is an example of American and British English pronunciation differences. in Australia (EEVblog #362 - LED Tube Lighting Install & Theory; both speakers experienced electrical engineers) it is standard to pronounce LED as an acronym, and thus the article is "a", like "a lead weight". In North America, it's common to pronounce it as an initialism, so it's written "an L.E.D." I have conflicting information about the UK. "Driving LED matrix displays with an FPGA" uses "led" (speaker make and sells large LED matrix displays commercially, so presumably knows industry standard usage), while "Make An L.E.D Illusion Mirror!" and "Current variation between LED tapes (both hobbyists) use "L.E.D.".
There's a good discussion at https://english.stackexchange.com/questions/90542/leds-and-the-correct-pronunciation
Given the amount of verbiage expended here on the subject, it's probably worth putting a brief mention in the article. Any opinions as to where it should go, or should I just WP:BE BOLD and stick a "Pronunciation of LED" at the end, just before "See also"? 71.41.210.146 (talk) 11:02, 16 September 2015 (UTC)
I wholeheartedly disagree with that idea, sorry. It is up to dictionaries to contain grammatical usage notes, not encyclopedias. Usage issues such as these need to be hammered out on the talk page, and then consistency be used correctly throughout the article.
And for the record, I agree that "an LED" is correct. Do note, however, it should be "a light-emitting diode" if spelled out. – voidxor 18:52, 16 September 2015 (UTC)
Er, I was proposing to describe pronunciation, not grammar.
And many many wikipedia articles include pronunciations. Some, like Pronunciation of asteroid names or List of names in English with counterintuitive pronunciations are nothing but.
There are also articles with pronunciation sections, particularly if there are multiple variants, e.g. Betelgeuse#Spelling and pronunciation and Lieutenant#Pronunciation.
Can you clarify what you imagine would constitute "grammatical usage notes" about what I was suggesting? I was intending to mention the a/an difference as part of it, but that substitution makes no grammatical difference (either way, it's a singular indefinite article, and LED is still a noun), so even it doesn't qualify. 71.41.210.146 (talk) 18:05, 17 September 2015 (UTC)
No, you were proposing to add a commentary on grammar. Which article ("a" versus "an") should be used in a given case follows simple grammatical rules. The rule is: If the word immediately following a non-specific singular article starts with a vowel sound (not whether it literally starts with a vowel!), the article "an" should be used; otherwise "a" should be used. "LED" is pronounced "ell-eee-dee", period. End of story. Look it up. Several other editors in the above discussion have tried to tell you as much, too. So, not to be mean, but can we please close this discussion? – voidxor 19:09, 17 September 2015 (UTC)
"LED" is pronounced "ell-eee-dee", period. End of story. Look it up. No, It is not.
As I documented above, there are regional differences and both are in common use. One of the links I posted above shows, the split is about 80% "L.E.D." and 20% "led", and that has remained stable since 1980. (Before then, "led" was more common, actually being in the majority before 1969.)
Also, as others in this thread have noted, larger terms like "OLED" are more commonly pronounced "oh-led". 71.41.210.146 (talk) 20:20, 17 September 2015 (UTC)
Yes, but you were talking about whether "a" or "an" should be used. That's a simple grammatical derivation of the pronunciation. Whether it's "a" or "an" (as this discussion is titled) is a grammatical issue that follows the pronunciation you're wanting to discuss. It would appear you're in a minority. But what we need to do is separate the two discussions; on the one hand is the issue of "should this article consistently use "a LED" or "an LED". That was the purpose of this tread before it was hijacked into a discussion of the second issue: whether pronunciation is a regional issue that should be explained near the top of the article. So, I would say that if you want to discuss that issue, which has absolutely nothing to do with whether this article should consistently use "a LED" or "an LED", I suggest starting a new thread—maybe a !vote—instead of reviving or hijacking five-year-old arguments which are already ridiculously long. – voidxor 21:46, 18 September 2015 (UTC)

Regarding A/An, in this article, "an" is obviously the correct choice. The "L.E.D." pronunciation is far more common, particularly when addressing a general audience (which WP is) and in general contexts where the single syllable "led" risks ambiguity. No question there. Even in places where "led" is used professionally, advertising uses "L.E.D." consistently.

But I thought that the "led" pronunciation has sufficient history and popularity (i.e. length and breadth of usage) to be worth a mention (with wp:weight appropriate to its minority status). The discussion here in the talk page seems evidence enough of that. The fact that there is a lexical (as opposed to grammatical) difference in the choice of a/an lets the pronunciation be inferred from the written form, which makes the whole thing easier to document.

As for "at the top of the article", no. That's the traditional place, but anything larger than "(English: /ɛliːˈdiː/ or /lɛd/, see below)" would be too large and distracting. I was thinking of putting it at the bottom, and wasn't planning on anything in the lead (other than the TOC), although I'm actively soliciting input on that point. 71.41.210.146 (talk) 12:15, 20 September 2015 (UTC)

P.S. While I'm at it, let me see if I can get a {{Respell}} version working. Echoing the IPA stress, that's el-ee-dee and led. 71.41.210.146 (talk) 13:18, 20 September 2015 (UTC)

All I'm saying is that this thread is about whether "a LED" or "an LED" should be used throughout the article. As you point out, that's an obvious decision and clearly we've formed a consensus. However, you and others have strayed off of that original topic to discuss two more issues: which pronunciation is correct/popular, and whether there should be a mention of regional pronunciation differences in the article. I'm not disputing what you say; I'm honestly just trying to get you to start a new thread so that:
  • We're not constantly reviving five-year old threads.
  • Threads don't get unmanageably long.
  • You don't confuse people as far as what you're proposing. Admittedly, I initially thought you were suggesting this article should use "a LED" throughout, when in fact you were proposing a mention of pronunciation differences. My confusion occurred because of the thread in which you elected to embed your proposal.
  • We can boil your proposal down to a yea or nay !vote, and attract comments from fresh eyes not wanting to read a ream of circular discussion.
  • We can finally put the "an LED" vs. "a LED" debate to rest, which cannot occur as long as people continue to revive this thread.
I'm respell illiterate so I can't help you there. – voidxor 23:35, 24 September 2015 (UTC)

History of Blue LED

This is missing from the Blue LED section: Nakamura's GaN types were not the first blue LEDs. Blue LEDs were first developed by RCA in 1972. [1] And SiC-types were first commercially sold in the U.S. by Cree in 1989. [2]. I also know this because I bought & still have them :-) They are not very bright.

Rich S 10001 (talk) 20:26, 26 August 2015 (UTC)

  1. ^ Link.
  2. ^ Link
@Rich S 10001: Looks good, and welcome to Wikipedia! This is a volunteer project, as you know, so we generally encourage new editors to be bold, and add new content to the article yourself (as long as it has references, which you have already done). If you don't yet feel comfortable doing it, reply below and I'd be glad to do it. – voidxor 20:25, 27 August 2015 (UTC)
 Done. Since we haven't heard back, I went ahead and added it. Thanks for the submission! – voidxor 20:34, 14 September 2015 (UTC)

Section "Covers" relevant?

Frankly, I don't see the relevance of the information about LED covers for the article. Besides, said section is written rather poorly (imho), with lots of redundant content. Noggo (talk) 19:28, 16 October 2015 (UTC)

  • Remove. It reads like an advertisement, which is why I tagged it as such in August. I did a little work on it at the time, but it still contributes nothing to this article. Just now, I noticed it only has one reference so I tagged it {{Refimprove section}} as well. Note that the section originated as a separate article, and an AfD discussion concluded it should be merged here. To quote that discussion, "Obviously consensus at the destination is free to determine how much material, if any, should be integrated..." I guess that means we are free to decide what to do with it from here. – voidxor 20:09, 16 October 2015 (UTC)
  • Gone. Andy Dingley (talk) 20:55, 16 October 2015 (UTC)
  • Agreed. It's not relevant to this article. Jeh (talk) 21:34, 16 October 2015 (UTC)

Comments and questions

This is a very well written article. It flows and it's very clear. However, I feel it contains a little too much information. Also, I feel it is informative but it is not particularly entertaining from a reader's standpoint (my background is technical).

I would like to add a series of comments and questions.

1. "Blue LEDs were first developed by RCA in 1972.[32] SiC-types were first commercially sold in the United States by Cree in 1989.[33] However, these initial blue LEDs were not very bright."

Which ones? 1972 or 1989 versions?

2. "Nakamura, Akasaki and Amano were awarded the Nobel prize in physics for their work."

It would be nice to add the year.

3. "It has been speculated that the use of six-inch silicon wafers instead of two-inch sapphire wafers and epitaxy manufacturing processes could reduce production costs by up to 90%."

This was speculated. What is the actual figure now?

4. "Note that these efficiencies are for the LED chip only, held at low temperature in a lab. Lighting works at higher temperature and with drive circuit losses, so efficiencies are much lower."

As usual, just like with cars and fuel efficiency, LEDs efficiency is biased primarily for marketing purposes since most applications do not work at "low temperatures".

5. "LED light output rises at lower temperatures. Thus, LED technology may be a good replacement in uses such as supermarket freezer lighting, and will last longer than other technologies. Because LEDs emit less heat than incandescent lamps, they are an energy-efficient technology for uses such as in freezers and refrigerators."

The two sentences are redundant.

6. "High-brightness blue LEDs invented by Shuji Nakamura of Nichia Corporation using gallium nitride revolutionized LED lighting, making high-power light sources practical."

What was the year?

7. Why is ultraviolet light called black light if it's indeed violet and not black?

8. What are "pi electrons"?

9. "Ultra-high-output: 20 mA at approximately 2 or 4–5 V, designed for viewing in direct sunlight."

I don't understand what this sentence means.

10. The naming for high-power LEDs (HPLEDs) or high-output LEDs (HO-LEDs) is not consistent (the second has a hyphen while the first doesn't). Is there a reason?

11. The first sentence of most of the subsections of "Application-specific variations" is not in the SVO form.

12. "Usually they are packaged in a sealed enclosure similar to a lamps they were designed to replace. "

This sentence is ambiguous.

13. What are "cool-white LEDs"? Why white light should be "cool"?

14. "Plant growers are interested in LEDs because they are more energy-efficient, emit less heat (can damage plants close to hot lamps)".

This fragment does not make much sense. The sentence needs to be revised.

ICE77 (talk) 03:33, 10 November 2015 (UTC)

Thank you for your read through and helpful cleanup. The ambiguities you're listing should certainly be fixed or mentioned inline in the article. So with that in mind, using your numbering scheme:
  1.  Fixed by adding "neither". The ambiguous sentence was purely a transition into high-brightness blue LEDs.
  2.  Already done by an anonymous editor.
  3. minus Removed, as I don't think speculation about how to improve manufacturing costs is very encyclopedic. The source was from 2009 and white LEDs are certainly a lot cheaper now.
  4.  Question: That being the case, how should we address it?
  5.  Fixed by rewording for simplicity.
  6.  Partly done by tagging {{When}}.
  7. no Disagree because it's not violet; it's ultraviolet, meaning that it's higher than violet in the spectrum. See Black light.
  8.  Fixed by linking to Pi bond.
  9.  Fixed by changing the formatting. You don't understand the sentence because it's not a sentence; it's a sentence fragment and therefore shouldn't have a period. I've converted it to a definition list per MOS:DEFLIST.
  10.  Fixed a Google search revealed they should probably all have hyphens. I've added the missing ones.
  11.  Fixed by forming complete sentences.
  12.  Fixed by making it clear that we're talking about the shape of the enclosure (e.g. a bulb).
  13. no Disagree. See Color temperature, which is already linked from that section.
  14. minus Removed as non-encyclopedic ambiguous application-specific anecdotal outdated uncited text.
– voidxor 01:22, 12 November 2015 (UTC)

voidxor, thanks for implementing a variety of improvements after reading my comments and questions.

4. I would probably replace data at low temperatures with data at room temperature.

7. I will have to read the article about "black light" to understand.

13. It looks as if "cool-white" light has a temperature of 5,000 K. I'll have to read about it.

ICE77 (talk) 21:57, 16 November 2015 (UTC)

@ICE77: I agree wholeheartedly on #4, but do you know of any such data sources? – voidxor 22:29, 17 November 2015 (UTC)

4. I don't know of any information on data at room temperature.

ICE77 (talk) 18:28, 18 November 2015 (UTC)

How about we just remove the efficacy table for now? It's pulled straight out of the 2012 Philips catalog and only applies to their specific models. They may or may not have been the top efficiencies at that time, but I doubt they are now, so I don't know why they're noteworthy enough to include here. Doing so implies that all LEDs of each given color operate at nearly that exact efficacy. – voidxor 22:01, 18 November 2015 (UTC)

voidxor, you just hit the bullseye. Marketing figures have a history of being not always practical. I have seen tons of stuff like that in solar cells going into solar panels or cars tested in a lab and hitting the road.

ICE77 (talk) 19:36, 20 November 2015 (UTC)

"wire bond" undocumented, past documentation provided but deleted

A "wire bond" or jumper is provided in most LED which is not for current flow but to temporarily prevent immediate damage from reverse polarity connections, which small led otherwise would be (Forest Mimms III, Archer notes). The feature is limited since the jumper also must not bypass all forward current; it is a comprimise feature that allows only very brief (circuit on, or test touch) reverse current. (electrons jump the gap which can be seen with a magnifying glass)

(another proof: cpu chips contain min-transistors and DO emit light (which is why they are packaged in DARK glass. do CPU have jumper wires between each transistor or for that matter do transistors or vaccum tubes? NO. neither do LED except as a convenience feature)

(motherboard/cpu also emit radiation while on, so leaving them outside of an enclosed metal box is not suggested)

false information in article

a picture shows "gold wire bond" i beleive is incorrect. the wires shown appear to be circuity wires not a jumper bridge between the NP layer of the 1/2 transistor (LED, diode)

way too much information on a not-so-important topic, in article

please make a "infatuated about led" article and move material there

— Preceding unsigned comment added by 72.219.204.96 (talk • contribs) 14 dec 2015 23:40‎ (UTC)

So you only want to read information that you already know?? SpinningSpark 14:59, 12 January 2016 (UTC)

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Disadvantages - Light Pollution

Note revision to remove incorrect (yet still widely repeated) statement that Rayleigh scattering increases light pollution, particularly sky glow, from white LED used in outdoor applications. The topic is the subject of recent peer-revewed research (discussed and referenced on Light Pollution and Sky Glow pages, and also referenced here now).

Also previous statements about some dark sky advocacy orgs (i.e. International Dark-Sky Assoc) are not appropriate in this level article on LED. Besides, the IDA recommendation is controversial.

The phrase "Light Pollution" often has much broader meaning than just sky glow (such as ecological impacts, touched on narrowly in another "Disadvantages - Impact on insects" bullet, impacts on human health, glare, etc.). Probably it would be most sensible to continue with "Light Pollution" as addressing sky glow (as seen by humans) as it is arguably the most common meaning for light pollution, then broaden the "Impact on insects" to address "Impacts on ecosystems" and add "Impact on (human) health." Cluginbuhl (talk) 18:35, 15 April 2016 (UTC)

Relate LED voltage drop to material direct bandgap

How does the voltage drop of an LED relate to the direct bandgap of the material ? (eg is it Slightly higher by the voltage drop of the rest of device which depends on the current ?) Could we also have a formula that relates the energy of the emission peak photons to the direct bandgap (is it just Ep=bg?) - and an explanation of why the emission curves have a FWHM of about 25nm ? - Rod57 (talk) 18:21, 29 October 2016 (UTC)

Dubious voltage drop figures not sourced - eg for UV

In the table in Light-emitting_diode#Colors_and_materials the voltage-drop figures (unsourced) seem unlikely. It might be clearer to have a voltage drop per material rather than per colour range. The UV range is too wide and could be split into UVA, UVB, UVC at least ? - Rod57 (talk) 13:53, 2 November 2016 (UTC)

lighthouse package

no info in article about uses/dis/advantages of this package shape design. — Preceding unsigned comment added by 92.19.42.51 (talk) 15:52, 23 November 2016 (UTC)

efficiency

Article states in the Technology section that temperature has been shown to make LED's actually more efficient (contrary to popular belief). It also states that they are used in freezers and that the low temps make them more efficient. I dont have the time to effectivly edit and fact check these things but maybe someone else does. Thanks!! Galenanderson (talk) 01:04, 20 January 2017 (UTC)

COB LEDs

Please would someone add information about COB LEDs ? How they are constructed ? Many thanks ! Darkman101 (talk) 22:36, 6 April 2017 (UTC)

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Semi-protected edit request on 14 May 2018

I have redrawn the image

Combined spectral curves for blue, yellow-green, and high-brightness red solid-state semiconductor LEDs. FWHM spectral bandwidth is approximately 24–27 nm for all three colors.

and made it an SVG: File:RGB_LED_Spectrum.svg

Feel free to use it if it could be of any use here. Cpu20 (talk) 15:21, 14 May 2018 (UTC)

 Done. Nice work, thanks. ~Anachronist (talk) 16:29, 14 May 2018 (UTC)

Manufacturers' names

This article is full of names of manufacturers and specific products. There are two objections to this. One is that the information is constantly going out of date, because of rapid progress in this section of the electronics industry, although I have been trying to update it and future-proof it. The other is that it seems unfair to mention only a few manufacturers when there are so many of them. If the references to product data sheets are removed, the number of in-line citations will be very limited, and in-line citations are supposed to be essential in Wikipedia articles. These are all facts of life, common to any article that is so closely tied to commercial products. What is the official policy in this area? EEye (talk) 17:07, 31 January 2019 (UTC)

Early blue LEDs

The article on selenium claims that the first blue LEDs were based on ZnSe which in this article is only mentioned briefly in the "Other whites" section. I believed that the first (but I have no idea about when) blues were Russian SiC-based low-efficiencies LEDs later commercialised by Siemens. Interesting to learn about the early (1972) GaN work.150.227.15.253 (talk) 10:29, 19 March 2020 (UTC)

"Two-way LEDs"

As I understand, any old LED can also be wired to work as a (bad) phototransistor. Rapid switching circuitry can be used for detecting light as well as emitting. Maybe this should be mentioned in the section. --BjKa (talk) 13:14, 1 October 2019 (UTC)

Yes, photodiode, not phototransistor. Why don't you find such a reference to its practical application in that way and edit it into the article?Interferometrist (talk) 13:28, 1 October 2019 (UTC)
There is one reason to do it, which is that it is a good for two-way (half duplex) optical communications devices. If the alignment is right for one way, it is right for the other way. Otherwise, Si photodiodes, and especially PIN photodiodes are better. Gah4 (talk) 19:44, 19 March 2020 (UTC)

Missing types

The article has very little information on the chronology and development of green (and yellow) LEDs. I remember that before the modern blue LEDs appeared there were "super reds" (dope with ZnO i believe), when were they developed? Now that there are bright red, blue and whites, have any bright greens, yelllows and oranges appeared to fill the gaps in those spectral areas? 150.227.15.253 (talk) 10:44, 19 March 2020 (UTC)

I believe yellow is just a shift up in the gap of GaAs1-xPx, increasing x. For green, GaP is indirect gap, but nitrogen doped GaP:N has a bound exciton which can recombine for radiative recombination. Some improvement in red came from using Ga1-xAlxAs instead. Gah4 (talk) 19:49, 19 March 2020 (UTC)

Are any LEDs or components made in the United States?

In this item from Consumer Reports, few lights were made in the USA. However, this was 2011, nine years ago. Does anyone with industry knowledge know if any LEDs and/or components are currently made in the USA? Thank you for your time, Wordreader (talk) 00:41, 18 July 2020 (UTC)

In CR, that would probably be light bulb replacements. This article is more about the either separately encapsulated devices, or the chips that go inside larger devices. My guess would be that chips might be made in the US, and sent away for encapsulation or device manufacture. The made in label is where the last parts of the assembly are done. Gah4 (talk) 19:38, 23 November 2020 (UTC)

LED Contact burning spots onto Skin?

I have a dark freckle like spot on my stomache where I used to rest my old laptop while it leaned on my legs. It's exactly where the orange LED on the front was in contact with me. There's no mark on any of my shirts, it was only in direct contact with my skin a few times. How long does exposure take before skin darkening occurs? — Preceding unsigned comment added by 207.112.55.242 (talk) 10:45, 23 November 2020 (UTC)

Orange LEDs don't make any UV, which might be related to skin darkening. But that would be months or years. Gah4 (talk) 19:34, 23 November 2020 (UTC)
Actually some LEDs use a UV LED and employ a phosphor to turn the UV into other colours. An orange phosphor sounds quite likely. I'd recommend you cover the LED with black tape to avoid this issue. GliderMaven (talk) 19:05, 2 February 2021 (UTC)

Fairy Lights?

This term is unlinked to any article, no doubt because such an article doesn’t yet exist. Ought not it to have some explanation or definition, e.g. decorative lighting? Is the term universally understood? Anyone ? --2001:44B8:3102:BB00:5188:52A3:D68:B969 (talk) 03:07, 23 November 2021 (UTC)

Wiki Education Foundation-supported course assignment

This article was the subject of a Wiki Education Foundation-supported course assignment, between 1 April 2019 and 5 June 2019. Further details are available on the course page. Student editor(s): Abunc001.

Above undated message substituted from Template:Dashboard.wikiedu.org assignment by PrimeBOT (talk) 02:34, 17 January 2022 (UTC)

Pronunciation

User:GliderMaven has recently added the pronunciation /ɛlid/ for LED. No source was cited, and the pronunciation doesn't even make sense.

Lexico gives the pronunciation /ɛliːˈdiː/. But including this in the article isn't necessary per MOS:PRON because it's just the letters LED. Unless a source can be provided for /ɛlid/, I think there shouldn't be a pronunciation in the article at all. --Un assiolo (talk) 18:20, 2 February 2021 (UTC)

I checked and the pronunciation macro doesn't even support 'di' but it does support 'd'. You're really just being very tendentious indeed. And it does actually matter even within wikipedia is it 'an LED' or 'a led'? It goes beyond simple 'how do I pronounce it' and encroaches on grammar that is used in articles. How about you try not being a WP:DICK, yeah? GliderMaven (talk) 19:01, 2 February 2021 (UTC)
I have license to be a Dick, so let me emphasize his point that /ɛlid/ doesn't make any sense. What is it supposed to mean? It seems like it would suggest "elid". And actually, LED is sometimes pronounced "led"; it's not clear to me that we need to claim it's one or the other. Dicklyon (talk) 19:11, 2 February 2021 (UTC)
How shall we pronounce GASFET, Lord? Or JFET ? Or CMOS ?


Not sure this is right way to go about it, but in about the middle of the article where pros and cons are summed up, in the cons section I now see for second time LED written as "an LED". From Holland, English not native language, believe it should be "a LED" (something to do with vowels and the other ....uhm these aeiuo and these qwrtp etc.... that understandable ?). So since now see it twice i am doubting if i am right, minor detail anyhow, but there you go (or not ?). Bye.

PS Now see was discussed here before, not understanding reply of last person, leaving my comment, seems not resolved before. What one little letter cannot do ! — Preceding unsigned comment added by G Wijnsma (talk • contribs) 09:40, 13 October 2022 (UTC)

It is most often pronounced as three letters: ell ee dee, and so the pronunciation sounds better with an. I do know many, including physics researchers, who pronounce it as a word that sounds like the element Pb in English. In the latter case, it would be a led. I don't know if there is a WP:MOS for this. Gah4 (talk) 20:19, 13 October 2022 (UTC)

radiance and brightness

The brightness article suggests that it should not be used. In much of optics, radiance is important, as it is conserved (or lost) in an optical system. In some cases, it is the total optical power, and some cases the power per unit area of the source. The above section mentions brightness in the context of laser diodes. A laser diode emits from a very small area, and so even with the same power output, has much higher radiance. There is also radiant intensity when one does not consider the area of the source, especially for a diffused source. Gah4 (talk) 20:34, 13 October 2022 (UTC)

Physics

Improving and expanding the section on Physics would greatly improve the quality and usefulness of this article.

Specific comment: "Also unlike most lasers, its radiation is not spatially coherent, so it cannot approach the very high brightnesses characteristic of lasers." makes no sense to me. I cannot understand how coherence affects intensity at all. The low divergence of the laser beam helps with intensity at long distances compared to other devices, but this has nothing to do with coherence.

More generally, I don't understand the physics explanation of how these work. Most semiconductor detectors work by a photon absorption "popping" an electron into the conduction band (ok, yes, and a hole, too). The "bias" as I understand it, is a voltage applied to help with the collection of electrons - conduction band electrons will be attracted to a + charged electrode. What I don't understand is how you reverse this to get an LED: Let's say you put a "-" charged electrode in the active area, and it can dump electrons into the conduction band with a voltage higher than the band gap. Let's say these electrons then emit light by falling back down to the ground state band. How is this anything but exactly the definition of pumping a lasing medium? Why isn't this a laser without the cavity? (Or are there a continuum of states above the band gap, and so stimulated emission (requiring exactly the right energy) will only rarely occur?)... Anyway, clarification of this and LED vs. laser physics would I think really improve the article. Thanks, 192.184.155.113 (talk) 22:54, 18 October 2021 (UTC)

Laser diodes are commonly double heterojunction, materials with a larger band gap surrounding the active region. That allows for a higher carrier concentration needed for laser operation. As for brightness, as I note below, it should be radiance. Laser operation allows for emission from a smaller area, and so higher radiance. This is important in optical systems, as it allows for focus into a smaller spot. Most of this should go into the laser diode article, though, but this one should get radiance right. Gah4 (talk) 20:49, 13 October 2022 (UTC)

QLED

This article should probably mention QLED somewhere. - dcljr (talk) 11:23, 15 October 2022 (UTC)

Requested move 21 February 2023

The following is a closed discussion of a requested move. Please do not modify it. Subsequent comments should be made in a new section on the talk page. Editors desiring to contest the closing decision should consider a move review after discussing it on the closer's talk page. No further edits should be made to this discussion.

The result of the move request was: not moved. No support for move, and MOS:ACROTITLE also states, "Many acronyms are used for several things; naming a page with the full name helps to avoid clashes." Fuzheado | Talk 07:29, 28 February 2023 (UTC)

Light-emitting diode → LED – Per MOS:ACROTITLE: "Acronyms should be used in a page name if the subject is known primarily by its abbreviation and that abbreviation is primarily associated with the subject". That is the case here. The full name mostly makes sense for electrical engineers and not the common reader on Wikipedia. PhotographyEdits (talk) 09:51, 21 February 2023 (UTC)

  • Oppose - in common usage "LED" seems to refer quite often to LED lamps, LED strip lights, LED displays, etc. - not the electrical "diode" itself - so it fails the 2nd condition of the guideline. The 1st condition is debatable because, in electrical contexts, the full term is highly-used. This move would add ambiguity and make the topic of the article less clear. -- Netoholic @ 05:01, 22 February 2023 (UTC)
    @Netoholic I think we should aim for WP:CONSISTENCY with precisely the articles you linked. PhotographyEdits (talk) 09:00, 22 February 2023 (UTC)
    CONSISTENCY comes from having good guidelines and adhering to them - this proposed move does not achieve that. -- Netoholic @ 19:22, 22 February 2023 (UTC)
    I don't see any guideline that I am violating here. What I am doing is complying with MOS:ACROTITLE. PhotographyEdits (talk) 12:18, 23 February 2023 (UTC)
  • Oppose - Many things are commonly known by a shorter name, for convenience. That doesn't mean that we need to rename the page. I presume that there is a link, and readers will soon find the page. Gah4 (talk) 09:32, 22 February 2023 (UTC)
    We should name the page that is most logical according to policy and guidelines of Wikipedia. If that involves renaming the page is not relevant. PhotographyEdits (talk) 09:59, 22 February 2023 (UTC)
  • Oppose per the above. A good case can be made that LED should remain a WP:PRIMARYREDIRECT versus the other things listed at LED (disambiguation).  — SMcCandlish ☏ ¢ 😼  07:06, 23 February 2023 (UTC)
  • Oppose per above. XtraJovial (talk • contribs) 23:52, 23 February 2023 (UTC)
  • Strong support LED is the most common name. GliderMaven (talk) 06:02, 24 February 2023 (UTC)
  • Oppose—I wouldn't mind "Light-emitting diode (LED)", though. Tony (talk) 00:13, 28 February 2023 (UTC)
The discussion above is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.
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