Incandescent Lamps

The most profound invention since man-made fire

History of the Incandescent Light (1802 - Today)

Introduction & Statistics	Inventors and Developments
How it Works	Flashbulbs
History and Developments

The incandescent lamp was the second form of electric light to be developed for commercial use after the carbon arc lamp. It is the second most used lamp in the world today behind fluorescent lamps. In this page we cover the traditional incandescent lamp. Halogen lamps are also incandescent light sources, but they have their own page here. The traditional incandescent bulb is not just a light source but has become a symbol of innovation.

Advantages:
*Great for small area lighting
*Good color rendering: CRI of 100 which is the best possible
*Cheap to produce
*No quantity of toxic materials to dispose of (like mercury, toxic alloys, or semiconductors)
*Is easily used in strobe or dimming circuits

Disadvantages:
*Not energy efficient (90% of energy goes to heat, 10% makes visible light)
*Traditional incandescent light bulbs are not useful for lighting large areas. It takes many to light a large area where as only one HID lamp can light a large open area. Halogen incandescent is useful for this purpose but it is not covered on this page.

Statistics *CRI 100 (best CRI possible) *Color Temperature - comes in all variations, but normally 2700 - 5000K *Lumens per watt 8 - 24 *Lamp life: 750 - 1000 hrs (standard household bulb) life can be greatly extended by using the lamp at a lower than normal voltage. Common uses: used everywhere for almost any application. From 1-10,000 W.

1. How it works

2. History and Developments

3. Inventors

Below: Video on the incandescent lamp. 6 min. YouTube must not be blocked by your server.

 

1. How it Works

Incandescent bulbs work by sending electric current through a resistive material. Typically materials will glow before reaching a melting point. Most materials will glow a dull red color when they reach around 525 Celsius. Most materials will catch fire or melt and can not make a good filament.

Filaments are made from materials that have a high melting point. Tungsten can reach up to 3422 C before it melts. This is a higher temperature than any lamp will reach (except the carbon arc lamp which gets to 3500 C). Other materials have made good filaments or parts of filaments including tantalum, molybdenum, and carbon.

Why does the material emit light when you pass electrical current through it?

When you pass current through a filament material, the resistance creates heat. Atoms in the material absorb energy. Electrons around the atoms are excited and temporarily reach an orbital which is further from the nucleus. When the electron orbit collapses to a lower orbital it ejects the extra energy in the form of a photon.

Incandescence is thermal radiation. Heat is constantly emitted from objects around us, we just can't see it. When heat gets intense enough it reaches wavelengths that we can see. It starts with red and goes up the spectrum. The wavelength/color of the light is a matter of how much energy is being released and what kind of atom is doing the release. In an incandescent bulb most of the heat energy (90%) is emitted in the infrared spectrum which is just below visible light. This is also what makes the lamp inefficient. We don't use that part of the spectrum for the lamp's purpose, we only need the visible spectrum. This is a basic explanation. More can be read about the chemistry from your textbook or online.

2. History and Developments The history of the incandescent bulb is centered on the development of filament types, so we will organize it by filaments. Platinum and Iridium Filaments: 1802 -1880's Humphry Davy created the first incandescent light by passing current through a platinum strip. It caused a glow and did not last long, but marked the beginning of incandescent light development. Experimenters continued over the next 70 years to use platinum and iridium. Frederick de Moleyns used a platinum filament in an evacuated glass tube to make a light bulb. It was only mildly successful due to a blackening of the bulb, which blocked light output. Combustion of the filament material and blackening on the upward side of the bulb was a frustrating consistent problem for early lamp inventors. The platinum material was also expensive. Early inventors knew that making a vacuum in a bulb would help reduce blackening and lengthen bulb life, the problem was ways to better create a vacuum had to be developed. Heinrich Geissler was one of the early physicists to develop a good pump and system. Still, early bulb inventors 1802 - 1879 lacked a system good enough. As is typical with invention, many know the answer, but other technological developments are needed to move forward. Blackening of the incandescent bulb, video: Carbonized Threads and Paper: 1860's - 1883 Joseph Swan and Thomas Edison independently hit success by making a bulb that would last a reasonable number of hours. Swan used carbonized paper to create his early filaments. Edison first used carbonized sewing thread as a filament, he managed to get it inside a vacuum. This made his first practical lightbulb. He used carbonized sewing threads until 1880. Then he used paper bristol board. (Carbonized paper) This move increased lamp life to 600 hours. Why Edison Triumphed: Joseph Swan worked on the incandescent light idea since 1850. Swan did not succeed because he used only a partial vacuum in his bulb. He also used a carbonized paper filament. Edison figured out how to create a pure vacuum in his bulbs. He did this by heating up the bulb at the same time that he pumped out the air. He used a Sprengle pump. The Sprengle Pump to the left was used by Swan and Edison to pump air from the first light bulbs. Read more about the pump by clicking on the Scientific American article above. Above: See our collection of bulbs at the Edison Tech Center on display. Bamboo brings great improvements: 1883: As the story goes Edison was using a fan on a hot day, he unwound fine bamboo on a fold-out oriental fan. He carbonized it and tested it as a filament. He send assistants to Japan to find the type of bamboo that was used in that fan. They found it and imported the filaments. The first bamboo filaments had a square shape because they were cut from larger pieces using a certain process. He electroplated the bamboo directly to the lead in wires to avoid the high cost of platinum clamps. Later he used carbon paste to adhere the bamboo to the lead in wires. Our video about early Edison Bulbs with cellulose and bamboo filaments:   Cellulose Filaments: 1881 - 1904 Sir Joseph Swan developed the cellulose filament in 1881, however Edison continued to use bamboo filaments until the creation of General Electric in 1892. Cellulose filaments were replaced by Willis Whitney's GEM lamp filaments. Video about the Mazda Bulb:   The move to metallic filaments: The Era of Tantalum Tantalum Filaments: 1902 - 1911 Tantalum was the first metal filament on the market. Like tungsten it has a very high melting point, so it can be heated to incandescence without destroying itself like most metals. Tantalum was so vastly superior to all other filaments that it became king from 1902 - 1909. After 1909 the sintered tungsten lamp really began to gain popularity. The arrival of a ductile tungsten finally ended the reign of tantalum. Werner von Bolton(a Georgian living in Germany) discovered that using tantalum for a filament allowed for lower energy consumption and greater brightness. Siemens and Halske Company produced these bulbs. The tantalum filament became successful and became a major threat to General Electric's sales. This stimulated GE to invest more in it's recently formed research lab to try to come up with a better lamp. Left: A lit Tantalum Lamp on display at Siemens Forum in Munich, Germany Below: The hooks used to hold filament   Left: The WOTAN Lamp, made with a drawn-tungsten WOTAN was a trademarked name owned by Siemens & Halske GEM Lamp Metallized Filaments: 1904 - 1907 Willis Whitney of GE Schenectady develops a way to bake a carbon filament at 3000 C to create a filament that behaves much like metal. This improves efficiency by 25 %. This filament was used in the famous Mazda lamps which produced a very bright light. Sintered Tungsten Filaments: 1904 -1911 In 1904 sintered tungsten is developed by Alexander Just and Franz Hanaman (Austria). Tungsten improves the lamps efficiency by 100 % and is used by GE in 1907 after it buys the rights for it. *Tungsten and Molybdenum filaments were used by A.N. Lodygin (Russia) in a 1900 "Exposition Universelle" in Paris Ductile Tungsten Filaments: 1908 - today William D. Coolidge had been working with tungsten which proved to be a superior material for a long lasting lightbulb over any other material to date. Previous sintered tungsten filaments had been efficient, but brittle and not practical. Coolidge figured out how to heat tungsten and draw it out through heated dies of decreasing diameter. The result of his work was a workable, bendable (ductile) wire that was high strength and made a great filament material. The new material was used in bulbs in 1911 and this is still used today. See our inventors section below for more advancements in the incandescent bulb. The future of incandescent lamps: The Incandescent lamp has been in the average household for more than 120 years. In the last decade a major initiative to develop more efficient lightbulbs has replaced much of the world's bulbs with compact fluorescents. There has been significant resistance to bans on the incandescent bulb

3. Inventors and Developments

	1802 Sir Humphry Davy discovers incandescence in a platinum wire. He also is the discoverer of the first electric lamp type: the carbon arc lamp. England
	1841 Frederick de Moleyns patented a incandescent lamp within a glass bulb and a partial vacuum. He is one of many people working on the incandescent light bulb from 1840 to the 1870s. Many French and Germans contributed to research on the incandescent bulb. Moleyns is exceptional and helped others build on the idea. England
	1879 Sir Joseph Swan began working with the incandescent light long before Edison, however his biggest breakthrough was developed at the same time as Edison. Swan used carbonized paper as a filament in a partially evacuated bulb, this lasted several hours, which was a great achievement compared to the scores of inventors who couldn't get incandescence to last. Swan continued to improve the bulb. England
	1879 Thomas Edison is the most celebrated of incandescent inventors. He was able to succeed in creating the first reliable (therefore marketable) light bulb. His bulbs made after 1880 lasted a whopping 600 hours. He then hired lots of talented engineers and created the world's most famous "invention factory". West Orange, New Jersey
	1902 Werner von Bolton discovered that using tantalum for a filament increased efficiency, durability and bulb life. The age of metallic filaments had begun and Siemens and Halske held the patent. Germany Photo: Siemens
	1904 Willis Whitney counters the threat from the tantalum lamp with the GEM lamp: a unique process which creates a metallized filament. The GEM lamp is used in the Mazda series by General Electric. Schenectady, New York
	1904 Alexander Just and Franz Hanaman patent a sintered tungsten filament. Tungsten proves to be a good material, however it is fragile and hard to work with. It is a step towards the modern bulb Austria
	1908 William D. Coolidge revolutionizes the lightbulb by figuring out how to make tungsten ductile. This allows the lightbulb to be more durable, long lasting, and easily coiled (coiling is key to making more surface area and therefore more light). The invention is implemented in 1911. His invention is used in many other lamp types later on including the fluorescent, halogen, MH, mercury vapor, and other lamps. Schenectady, New York
	1912 Irving Langmuir developed 3 important improvements to the bulb: He worked with Lewi Tonks to develop an argon & Nitrogen-filled bulb, he also developed the tight coiled filament, and pioneered a thin molecular hydrogen coating on the inside of the bulb. All of these dramatically improved the bulb. Schenectady, New York
	1921 Junichi Miura at Tokyo Electric (this facility is now part of Toshiba) developed the double coiled filament. This greatly improved luminous efficacy and helped efficiency. Later others figured out how to mass produce this improvement. Notice on the photo left how the large coil is made of another coiled wire. Japan
	1925 / 1947 Marvin Pipkin developed the frosted etched bulb and later the silica coating on the inside of the bulb. These advancements helped diffuse the light, reduce glare with only 3-5% loss in light output. Cleveland, Ohio

Above: a Philips flashbulb with magnesium filament Photo: Wikipedia Commons

Flashbulbs

The traditional flashbulb is another type of incandescent lightbulb. Early flash bulbs used a aluminum, zirconium, or magnesium filament or aluminum foil. Current was passed through the material and it glowed. The melting and boiling point of aluminum, magnesium or zirconium is so low that the lamp would vaporize the metal, which further intensified the brightness. Early lamps would last one flash and had to be replaced. Early flashbulbs often had an Edison type screw in thread like a regular lightbulb. Later lamps could last a few flashes. Later on disposable flash bulb arrays were developed to allow many flashes without switching bulbs.

One of the greatest challenges in developing a flash bulb is not the bulb itself, but timing the bulb to match the camera shutter. This improved with the development of solid state electronics in the 1950s.

Modern flashbulbs found on most cameras are no longer incandescent bulbs. They are tiny xenon arc tubes. An electric arc is formed through xenon gas. These have the great advantage of being reusable. They have the disadvantage of being a shorter duration than incandescent flash bulbs. This means they have to be more precisely time

	1927 ?? at General Electric and Johannes Ostermeier both independently develop the first non-magnesium electric flashbulb. It is much safer than older bulbs. The General Electric Product is called the Sashalite. This light replaced dangerous magnesium powder lights. The new lamps burned aluminum foil in a bulb filled with oxygen. Ostermeier produced a product called the Vacublitz. Schenectady, New York
	1934 Philips Corp. Unknown inventor created the first modern flashbulb: it has a wire in an evacuated bulb. The wire burns ups in a more effective way than aluminum sheets of foil. This design has not changed much. Nederlands
	1960s ?? at Kodak develops the flashcube which has four single use small flash bulbs. The cube can be rotated to use the new bulb. Rochester, New York
	1968 John D. Harnden Jr. develops a both a static electronic photoflash assembly (1968) and disposable flashbulb lamp(1971) along with Bill Kornrumpf. The array of flash bulbs removes the need for replacing the bulb. This long plastic bar of bulbs was popular in the 1970s and 80s. Harnden also developed precise timing devices for the bulbs that used semiconductors which were new at the time. Schenectady, New York
	1968 William P. Kornrumpf developed the photoflash bulb assembly and disposable flashbulb array for low cost cameras along with John D. Harnden. Schenectady, New York

 

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Lamps are presented in the order of chronological development

Previous: The Arc Lamp 1800

Next: Nernst Lamp 1898

Arc - Incandescent - Nernst - Neon - Mercury Vapor - Sodium Lamp - Fluorescent - Halogen - EL - LED - MH - Induction

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Written by M. Whelan with additional research by Rick DeLair and Ryotaro Miyajima

Sources:
"The General Electric Story" 1999. by the Hall of History, Scientific American Magazine,
Wikipedia.com, Scienceclarified.com, Lexicon Siemensstast: Werner von Bolton
The Siemens Forum, Munich, Germany
Siemens.com
"Men and Volts" John Hammond. 1941
digitalcamhistory.com/1920s

Photos:
Edison Tech Center
Whelan Communications
Scientific American
John Harnden Jr.

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