21st Century Holiday Lights – The Story of the White LED

Of Christmas Lights Past –

201612-lm-picAs days grow short and darkness dominates the landscape, we humans turn to artificial lighting for both utility and aesthetic comfort. Before the advent of electricity, candles and lanterns were the light source of the day, and many a Christmas tree was adorned with candles and lanterns, much to the discomfort of the local fire department.  With the birth of electric power, incandescent bulbs quickly became commonplace thanks to the efforts of Thomas Edison and Joseph Swan.  Incandescent light bulbs were strung together to illuminate Christmas trees, and were often painted to create colored lights.  Electric Christmas lights of the time were rather large, consumed lots of electricity, and produced plenty of heat, owing to their inefficiencies in converting electrons to photons.  Like everything (except perhaps smart phones and soft drinks), the trend in Christmas lights was miniaturization, making the bulbs smaller, resulting in less energy use and a nicer visual effect.   While the marketing people were busy making prettier strings of lights, the engineers were busy doing what they do best – building a better light bulb.

Enter the Light Emitting Diode (LED)

The details of the first light emitting diode were first published in a Russian journal in 1927 by Oleg Losev, who conducted extensive research into semiconductors and the mechanism of light emission from them. His discovery, however, was not put to use for many years.  Then in the late 50’s and early 60’s, researchers at the Radio Corporation of America, Texas Instruments, General Electric, IBM, Bell Labs, and MIT became interested in this phenomenon. A patent for the first practical LED soon issued, (U.S. Patent 3,293,513), followed by development of the first visible spectrum (red) LED by General Electric.  From there, advancements (and patents) continued.  LEDs became commonplace for indicator lamps and displays.  Many of us EE types fondly remember the little jelly bean like LEDs and white breadboards, and the wonderful seven segment displays on our HP and TI calculators.  Remember ShELL OIL (710.77345)? 

The Elusive Blue

While red, green and yellow LEDs were commonplace in the 70’s and 80’s, blue was non-existent.   The emission of light by a P-N junction with an applied electric field is caused by the release of energy when charge carriers recombine in a forward biased P-N junction.  Most silicon and germanium based diodes dissipate energy in the form of heat, but alas, gallium phosphide and gallium arsenide phosphide diodes release this energy in the form of photons as well.  Doping the LED with various impurities changes the wavelength of light released, but blue was not produced using any of the known semiconductor materials of the time, and was considered unobtainable with those semiconductor materials.

…And on to White

Researchers at RCA discovered in the early 70’s that gallium Nitride (GaN) produced blue light, but early blue LEDs did not produce adequate light output to be commercially successful. Then in 1994 Shuji Nakamura of Nichia Corporation built a high brightness blue LED based on InGaN, an event that forever changed the lighting industry.  Isamu Akasaki and Hiroshi Amano were working on material improvements to GaN to substantially contribute to the success of the blue LEDs being developed by Nakamura. The three won the Nobel Prize in Physics in 2014 for their invention of blue LEDs.  Now with high brightness blue LEDs a reality, phosphor coatings could be used to convert some blue light to yellow light, and also to produce red and green light. Mixing these wavelengths of light together would result in light that appears white to the eye.  With these breakthroughs, the stage was set for the advancement and proliferation of white LED lighting that we see today in everything from interior lights to automobiles to computer and smartphone screens.

And Some Patent Drama

Shuji Nakamura of Nichia Corporation was the primary inventor of the blue LED that resulted in the proliferation of modern day highly efficient white LED lighting. His employer Nichia Corporation was initially willing to fund his research into GaN, but eventually stopped funding after concerns that the project was taking too much time and money to complete. Nakamura continued the research on his own, and in 1993 succeeded in making a blue LED with excellent light output characteristics. Nakamura then moved to California to take a teaching position at UC Santa Barbara where he became involved with Cree Inc., a US manufacturer of white LEDs.

In 2001, he sued his employer, Nichia Corporation, for $180 million US Dollars as part of a complex lawsuit with Cree, one of Nichia’s competitors.  He sought fair compensation for his invention, whose patents made Nichia immense profits.  When he left Nichia in the 90’s, the company reportedly gave Nakamura $200 as an award for his GaN LED invention. Nakamura asserted in Japanese court that he was the rightful patent holder and inventor, and should be justly compensated for his work. After several years in court, he agreed to settle for the equivalent of $8 million US Dollars.

The Nakamura lawsuit highlights the relationship between employer and employee when it comes to how ownership of intellectual property rights impacts innovation. While his lawsuit may have not fundamentally changed the way in which companies treat employee inventors in the same way as white LEDs have changed the lighting industry, the outcome has certainly drawn attention to the topic of fair and reasonable compensation for inventions made by employees.

GRAPHIC CREDIT:  “Inside an LED Lightbulb”.  Robert Gunderman.

Authors Robert D. Gunderman P.E. (Patent Technologies, LLC and John M. Hammond P.E. (Patent Innovations, LLC are both registered patent agents and licensed professional engineers.  Copyright 2016 Robert Gunderman, Jr. and John Hammond.

Note: This short article is intended only to provide cursory background information, and is not intended to be legal advice.  No client relationship with the authors is in any way established by this article.

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