wern@zoo.toronto.edu (Wern Thiel) (01/16/91)
Does anyone have comprehensive references as to who invented/developed the LED? While many components (transistor and IC's) are covered in books and texts; the LED seems to be missing. It would be interesting to read about the research that led to the LED. Similar situation regarding liquid crystal technology. We got our first LED in about 1974 for $10.
sirakide@motcid.UUCP (Dean Sirakides) (01/17/91)
wern@zoo.toronto.edu (Wern Thiel) writes: >Does anyone have comprehensive references as to who invented/developed the >LED? While many components (transistor and IC's) are covered in books and >texts; the LED seems to be missing. It would be interesting to read about >the research that led to the LED. Similar situation regarding liquid >crystal technology. We got our first LED in about 1974 for $10. One of the inventors is a professor of EE at the University of Illinois at Urbana-Champaign. His name is Nick Holonyak (He was the first PhD student graduated by James Bardeen (inventor, with two others, of the transistor)). He is still active (somewhat), so you could call him or more simply ask at the EE library at U of I since I'm sure they are famaliar with his published works. His office number is 217 333-4149. The U of I info number is 217 333-INFO. Hope this helps. Dean Sirakides Motorola Inc.
flower@hpcc01.HP.COM (Graham Flower) (01/17/91)
I dont have comprehensive references but I think you can probably find a good group of references in the book by S.M. Sze "The physics of Semiconductor Devices" Wiley, 1981. I believe the LED was invented by Nick Holonyak of the University of Illinois in Urbana. The above book has very little historical content, however. Graham Flower Hewlett-Packard, San Jose, Ca.
vail@tegra.COM (Johnathan Vail) (01/23/91)
In article <1991Jan16.034246.12843@zoo.toronto.edu> wern@zoo.toronto.edu (Wern Thiel) writes: Does anyone have comprehensive references as to who invented/developed the LED? While many components (transistor and IC's) are covered in books and texts; the LED seems to be missing. It would be interesting to read about the research that led to the LED. Similar situation regarding liquid crystal technology. We got our first LED in about 1974 for $10. On a related note: I was working on a CD player and on the circuit board was a normal looking glass diode, cathode band and all, that lit up red. It wasn't an indicator, and had a normal D number like the other real diodes on the board. Was the light emitted a side effect of the diode? Was it a special LED in this package for use to frop a certain voltage or something? Maybe some kind of diagnostic LED? jv ``Bunnies believe in deeds, not words.'' _____ | | Johnathan Vail | n1dxg@tegra.com |Tegra| (508) 663-7435 | N1DXG@448.625-(WorldNet) ----- jv@n1dxg.ampr.org {...sun!sunne ..uunet}!tegra!vail
wtm@uhura.neoucom.EDU (Bill Mayhew) (01/23/91)
LEDs can have interesting circuit properties aside from their light emitting abilities. An interesting experiment is to do an i-v plot on an oscilloscpe for an LED. LEDs at low current levels can also be modulated by ambient light, but isn't a terribly great detector. In a pinch, I've used an LED as a crude voltage regulator. The knee of the curve is about 1.8 volts, which beats hooking up three silicon dioes to get a handy 2 volt drop. Those low voltage Zeners can be rather inconvenient to find, if you're just fooling around just prototyping something. Most likely the glass LED in the CD player was just a pilot light. This especially handy if the CD player was a battery op model; it's easy to forget to shut down before poking around. Another use could be a disk presnet sensor light source if there were a photo transistor on an adjoining board... ==Bill== -- Bill Mayhew NEOUCOM Computer Services Department Rootstown, OH 44272-9995 USA phone: 216-325-2511 wtm@uhura.neoucom.edu ....!uunet!aablue!neoucom!wtm via internet: (140.220.001.001)
terryb@cs.fau.edu (terry bohning) (01/23/91)
vail@tegra.COM (Johnathan Vail) writes: > On a related note: I was working on a CD player and on the circuit > board was a normal looking glass diode, cathode band and all, that lit > up red. It wasn't an indicator, and had a normal D number like the > other real diodes on the board. > > Was the light emitted a side effect of the diode? > > Was it a special LED in this package for use to frop a certain voltage > or something? LEDs also make good low-voltage voltage regulators using the forward drop. I used one many years ago in a circuit. The ones I had didn't have a forward drop that was very consistent unit to unit, tho'. Forward voltage ranges from about 1 to 2 V as I recall, depending on type and color. This is great, tho', since zeners of this low value are hard to come by. "The forward conduction characteristic of the LED displays a much sharper knee than ordinarily obtained from forward-biased silicon junction diodes...Generally, satisfactory regulating action begins when the LED is just visible in the dark." From: "Regulated Power Supplies", Irving M. Gottlieb, Howard W. Sams, 1981, 3rd ed.
donm@hpnmdla.HP.COM (Don Montgomery) (01/25/91)
About 25 years ago I was working for a major semiconductor manufacturer in Quality Assurance. One of the test operators said she had thrown away a DO-7 silicon diode that glowed "yellow" when she forward biased the part. Needless to say, I got rather excited about this prospect of a diode that glowed, but she said she had thrown it out weeks before. Could this have been some monumental serendipity discovery that was tossed out? Our chemistry teacher in high school once told us that some of the world's greatest discoveries were poured down the drain in the lab... Don Montgomery donm@hpnmdla.HP.COM
dmturne@PacBell.COM (Dave Turner) (01/25/91)
In article <1991Jan16.034246.12843@zoo.toronto.edu> wern@zoo.toronto.edu (Wern Thiel) writes: >Does anyone have comprehensive references as to who invented/developed the >LED? While many components (transistor and IC's) are covered in books and >texts; the LED seems to be missing. It would be interesting to read about >the research that led to the LED. Similar situation regarding liquid >crystal technology. We got our first LED in about 1974 for $10. I found an article by Forrest M. Mims, III in an old Popular Electronics. Because it may be difficult for some to find I have posted much of it here. Mr. Mims has columns in Modern Electronics and Scientific American. Perhaps he could write an updated article? Light-emitting Diodes by Forrest M. Mims, III Popular Electronics November, 1970 p 35 One of the least known but most fascinating of semiconductor devices is the light-emitting diode (LED). Until quite recently, these devices were too expensive for widespread use; however, technological advances in their fabrication now make possible moderately low prices so that they are attractive to the electronics experimenter. The first recorded instance of light being generated by a "diode" was in 1907 when H. J. Round touched a pair of battery wires to a crystal of silicon carbide. Much to his surprise, flashes of yellow light were emitted at the contact region of one of the battery wires -- he had accidentally discovered the LED. Unfortunately, his discovery was forgotten and not until the early 1950's did scientists once again study semiconductor light emission. At that time several patents were applied for covering LED's made from silicon or germanium -- common semiconductor materials. One of these patents not only described the principle of the LED but listed several fascinating uses for the device. Among them were light-beam communication systems, light "radar", and light-beam alignment devices. Unlike the 1907 silicon carbide cat whisker diode, the 1950's LED's emitted infrared light (see Fig. 1) [ not included, dmt ]. The invisible beam was desirable but researchers began a concentrated effort to fabricate LED's in the visible range. The first company to market any kind of LED was Texas Instruments, Inc. Their diodes included infrared emitters made from gallium arsenide (GaAs) and visible emitters made from gallium arsenide phosphide (GaAsP). These diodes were expensive; but their appearance on the commercial market in 1962 whetted the appetites of design engineers -- and of course was of great interest to other semiconductor manufacturers. While scientists at IBM and Bell Telephone performed basic research on the devices (especially visible emitters), General Electric, Monsanto, Electro-Nuclear Laboratories and others began competing with TI. Since the LED has an almost unlimited lifetime and because of its low operating current, many claims were made for its potential in flat screen television, indicator lamps, night lights, and even as a source of room lighting. The extremely fast modulation capability of the LED made possible several demonstrations of voice communications permitting two parties to converse over a beam of invisible infrared light for clear weather distances of several miles. ... An important result of all these new uses for LED's is a large drop in price. LED's are available for under $2.50 each in small quantities. This price is competitive with that of miniature, long-life indicator lamps. And of course, the LED offers sturdier packaging, a million-hour lifetime, and far less current consumption. Only a year ago, the cheapest infrared LED retailed for $18.00. At least five manufacturers now offer GaAs LED's for under $7.50. ... GaAs diodes are so efficient as light emitters that scientists chose them as candidates for early work concerning the feasibility of fabricating semiconductor lasers. In the fall of 1962, researchers at G.E., IBM, and MIT announced almost simultaneously lasers made from specially prepared GaAs diodes. -- Dave Turner 415/823-2001 {att,bellcore,sun,ames,decwrl}!pacbell!dmturne
parnass@cbnewse.att.com (Bob Parnass, AJ9S) (01/25/91)
In article <1991Jan16.034246.12843@zoo.toronto.edu> wern@zoo.toronto.edu (Wern Thiel) writes: >Does anyone have comprehensive references as to who invented/developed the >LED? I found this passage in "Mission Communications - The Story of Bell Laboratories:" "Bell Laboratories research studies of certain semiconductor compounds by D. G. Thomas, J. J. Hopfield, C. J. Frosch and others at the Laboratories led to the discovery of the basic physical process by which light is created in gallium phosphide light-emitting diodes (LEDs)......" The book was written by Prescott C. Mabon and used to be available from Bell Labs, Murray Hill, NJ 07974. -- ============================================================================ Bob Parnass, AJ9S - AT&T Bell Laboratories - att!ihlpy!parnass (708)979-5414
david@cs.uow.edu.au (David E A Wilson) (01/28/91)
wtm@uhura.neoucom.EDU (Bill Mayhew) writes: >In a pinch, I've used an LED as a crude voltage regulator. The >knee of the curve is about 1.8 volts, which beats hooking up three >silicon diodes to get a handy 2 volt drop. Those low voltage Zeners >can be rather inconvenient to find, if you're just fooling around >just prototyping something. I was surprised to find a small red LED inside my CASIO fx-990 solar powered calculator (with no way it could be seen from outside) and came to the conclusion that it must be used as a regulator. -- David Wilson Dept Comp Sci, Uni of Wollongong david@cs.uow.edu.au
ken@uswat.uswest.com (Kenny Chaffin) (01/29/91)
In article <1991Jan28.031708.6748@cs.uow.edu.au-> david@cs.uow.edu.au (David E A Wilson) writes:
->I was surprised to find a small red LED inside my CASIO fx-990 solar powered
->calculator (with no way it could be seen from outside) and came to the
->conclusion that it must be used as a regulator.
It might have something to do with troubleshooting-???
KACleland@cbnewse.att.com (leland.m.kornhaus) (01/29/91)
My Sharp EL-515 Scientific solar calculator had two mini leds inside it - The solar cells had to be able to produce much more voltage than the calculator needed in full daylight in order to deal with the low light situations encountered indoors. The two leds in series clamped the voltage and easily dealt with the low current. An electrolytic capacitor stored about two seconds of reserve power.
graeme@labtam.labtam.oz (Graeme Gill) (01/30/91)
>In a pinch, I've used an LED as a crude voltage regulator. The >knee of the curve is about 1.8 volts, which beats hooking up three >silicon diodes to get a handy 2 volt drop. Those low voltage Zeners >can be rather inconvenient to find, if you're just fooling around >just prototyping something. I've seen LEDs used as voltage references in Audio equipment, as the forward biased diode is noticeably quieter than a reverse biased zener diode. Graeme Gill Electronic Design Engineer Labtam Australia