hpr-knowledge-base/hpr_transcripts/hpr3192.txt

Episode: 3192
Title: HPR3192: A light bulb moment, part 3
Source: https://hub.hackerpublicradio.org/ccdn.php?filename=/eps/hpr3192/hpr3192.mp3
Transcribed: 2025-10-24 18:29:52

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This is Hacker Public Radio Episode 3192 for Tuesday 27 October 2020. Today's show is entitled,
a light bulb moment. Part 3
It is hosted by Mr. X
and is about 13 minutes long
and carries an explicit flag. The summary is
The LED Revolution.
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Hello and welcome Hacker Public Radio audience. My name is Mr. X and welcome to this podcast.
As usual, I'd like to start by thanking the people at HPR for making this service available to us all.
HPR is an invaluable service on these heritage groups.
HPR is a community-lit podcast provided by the community for the community.
That means you can contribute to why you pick up a microphone and record something and send it in.
I'm sure you could do that, couldn't you? If I can do it so can you.
And if we all did it, we'd have more shows that we know to do with.
Okay, so this is part 3 of my light bulb moment series
and it will follow on from where we left off.
This one is going to cover the development of the LED.
This, if the LED revolution is both long and complex, but I'll do my best to cover it,
please forgive me if I mispronounce some of the materials and processes as I'm not a lighting expert.
As I stated right back at the beginning of this series, most of the following excerpts are from Wikipedia.
The LED or light emitting diode first appeared as a practical electronic component in 1962.
The earliest LED emitted low intensity infrared light.
Infrared LEDs are used in remote control circuits such as used with a wide variety of consumable electronics.
The first visible light LEDs were of low intensity and limited to red.
Modern LEDs are available across the visible ultraviolet at infrared wavelengths with high light output.
A great deal of development and refinement was required to get to this point.
The first commercial visible wavelength LEDs were commonly used as replacements for incandescent and neon indicator lamps and then seven segment displays.
First, an expensive equipment such as laboratory and electronic test equipment, then later in such appliances as calculators, TVs, radios and telephones, as well as watches.
Until 1968, visible and infrared LEDs were extremely costly in the order of $200 per unit and so had little practical use.
The breakthrough came around in 1968 when Monsanto was a first organization to mass-produce visible LEDs.
These were red LEDs suitable for indicators.
In February 1969, he looked back at introduced the HP model 5082-7000 numeric indicator.
The first LED device to use integrated circuit technology.
It was a first intelligent LED display and was a revolution in digital display technology.
Replacing the next tube and becoming the basis for later LED displays.
The early red LEDs were bright enough only for use as indicators as a light output was not enough to illuminate an area.
Redouts and calculators were so small that plastic lenses were built over each digit to make them legible.
Yes, I remember that. I remember having one of these early calculators that you could barely see the digits and a very early digital watch.
Somebody pushed the button and it would come on briefly and you could see hours, minutes, seconds, month, day, date and all that sort of stuff.
It used so much power that it only came on briefly when you pushed the button.
Yes, I can remember those.
It shows you where an old fart I am.
Later, other colours became widely available and appeared in appliances and equipment.
The first blue-violet LED using magnesium-doped gallium nitrate was made at Stanford University in 1962 by Herb Muraska and Wally Rines.
In 1973, Pancov and Ed Miller demonstrated the first blue-electric luminations from zinc-doped gallium nitrate.
Though the subsequent device, Pancov and Miller built the first gallium nitrate light emitting diode emitted green light.
Today, magnesium-doping of gallium nitrate remains a basis for all commercial blue LEDs and laser diodes.
In the early 1970s, these devices were too dim for practical use and research into gallium nitrate devices slowed.
In 1993, high brightness blue LEDs were demonstrated by Suji Nakamara of Nietzsche Corporation using a gallium nitrate growth process.
In parallel, Aisama Akasaki and Hiroshi Amano in Nungai was working on developing the important gallium nitrate deposition on sapphire substrates and a demonstration of p-type doping of gallium nitrate.
This new development revolutionized LED lighting, making hyper-blue light sources practical, leading to the development of technologies like blu-ray.
I see what could be this, as in square bracket citation needed here.
In 1995, Alberto Barberi at the Cardiff University Laboratory, Great Britain, investigated the efficiency and reliability of high brightness LEDs and demonstrated a transplant contact LED using indium tin oxide.
I'm not even going to try and guess all this.
It's a capital A small L, capital G small A, capital I small N, capital P, and there's a forward slash, capital G small A, capital A, S, gallium nitrate.
In 2001 and 2002, processes for growing gallium nitrate LEDs on silicon were successfully demonstrated.
Fast forward to January 2012 and awesome demonstrated high-powered indium gallium nitrate LEDs growing on silicon substrates commercially.
And gallium nitrate on silicon LEDs are in production at places in the semiconductors.
White LEDs and illumination breakthrough.
So even though white light can be created using individual red, green and blue LEDs, this results in poor color rendering, since only the three narrow bands of wavelength of light are being emitted.
The attainment of high efficiency blue LEDs was quickly followed by the development of the first white LED.
In this device a cerium-doped phosphor coating produces yellow light through fluorescence.
The combination of that yellow with remaining blue light appears white to the eye.
Using different phosphors produces green and red light through fluorescence.
The resulting mixture of red, green and blue is perceived as white light, with improved color rendering compared to wavelengths from blue LED YAG phosphor combinations.
I have included a graph here that illustrates, it's called, now I'm not sure you pronounce this, H-A-I-T-Z-H-L-L, showing improvement in light output per LED over time with a logarithmic scale on the vertical axis.
So the first white LEDs were expensive and inefficient, however the light output of LEDs has increased exponentially.
The latest research and development has been propagated by Japanese manufacturers such as Panasonic and Nietzsche and by Korean and Chinese manufacturers such as Samsung, Kingsung and others.
This trend and increased output has been called, I'm going to mispronounce again, Hits Law, H-A-I-T-Z-L-L, after Dr. Roland Hits.
Light output and efficiency of blue and near ultraviolet LEDs rose and the cost of liable devices fell.
This led to relatively high power white light LEDs for illumination, which are replacing incandescent and fluorescent lighting.
Experimental white LEDs have been demonstrated to produce 303 lumens per watt of electricity, some can last up to 100,000 hours.
However, commercially available LEDs have an efficiency of up to 223 lumens per watt.
Below I've included some comparisons for incandescent bulbs, so for example I've got figures here for our standard incandescent bulb coming out at 12.6 lumens per watt,
and an example of a halogen bulb at 24 lumens per watt.
With LEDs continuing to get cheaper and even though for now they cost more than traditional bulbs, having this huge increase in electrical efficiency means overall cost is significantly cheaper than that of incandescent bulbs.
White indicator LEDs are known for their extremely long life, up to 100,000 hours as I previously mentioned.
Lighting LEDs are operated much less conservatively and consequently have shorter lives.
LED technology is useful for lighting designers because of its low power consumption, low heat generation and instantaneous on and off control.
And in the case of a single color LED, continuity of color throughout the life of the diode are in relatively low cost of manufacture.
LED lifetime depends strongly on the temperature of the diode, operating an LED lamp in conditions that increase the internal temperature, can greatly shorten the lamp's life.
I now use LED lighting in my own home, particularly in the areas where lighting is on for extended periods such as in the living room.
As you can see, we have come an extremely long way on a relatively short space of time, with advancements continuing to accelerate.
It's hard to appreciate the massive impact electric lighting has had in the world.
It's even harder to imagine living at a time not that long ago, where an expensive candle producing a puny amount of illumination was the only source of light,
with the added not incursible fire risk of having a naked flame, sharing a room with combustible materials.
With all these deterrents, it's little wonder that people just went to bed when the sun went down.
Right, well that's the end of my series on lightbulbs and I like.
I hope you found it interesting. If you want to contact me, I can be contacted at MrX at hpr at googlemail.com.
That's MRX ATHPR Theat symbol googlemail.com.
So until next time, thank you and goodbye.
Thank you.