What is a Fluorescent Lamp?
The history of the fluorescent lamp begins with early research into electrical phenomena. By the beginning of the 18th century, experimenters had observed a radiant glow emanating from partially evacuated glass vessels through which an electrical current passed. Little more could be done with this phenomenon until 1856 when a German glassblower named Heinrich Geissler (1815-1879) created a mercury vacuum pump that evacuated a glass tube to an extent not previously possible. When an electrical current passed through a Geissler tube, a strong green glow on the walls of the tube at the cathode end could be observed.
Because it produced some beautiful light effects, the Geissler tube was popular source of amusement. More important, however, was its contribution to scientific research. One of the first scientists to experiment with a Geissler tube was Julius Plücker (1801-1868) who in 1858 systematically described the luminescent effects that occurred in a Geissler tube. He also made the important observation that the glow in the tube shifted position when in proximity to an electromagnetic field.
Inquiries that began with the Geissler tube continued as even better vacuums were produced. The most famous was the evacuated tube used for scientific research by William Crookes (1832-1919). That tube was evacuated by the highly effective mercury vacuum pump created by Hermann Sprengel (1834-1906). Research conducted by Crookes and others ultimately led to the discovery of the electron in 1897 by J. J. Thomson (1856-1940). But the Crookes tube, as it came to be known, produced little light because the vacuum in it was too good and thus lacked the trace amounts of gas that are needed for electrically stimulated luminescence. An important stage on the long scientific path that lead to the fluorescent lamp was Alexandre Edmond Becquerel’s (1820-1891) observation in 1859 of the luminescence of certain substances when they were placed in a Geissler tube. He went on to apply thin coatings of luminescent materials to the surfaces of these tubes. Fluorescence occurred, but the tubes were very inefficient and had a short operating life. A few years earlier another scientist, George G. Stokes (1819-1903), had noted that ultraviolet light caused fluorspar to fluoresce, a property that would become critically important for the development of fluorescent lights many decades later.
While Becquerel was primarily interested in conducting scientific research into fluorescence, Thomas Edison (1847 – 1931) briefly pursued fluorescent lighting for its commercial potential. He invented a fluorescent lamp in 1896 which used a coating of calcium tungstate as the fluorescing substance, but although it received a patent in 1907, it was not put into production. As with a few other attempts to use Geissler tubes for illumination, it had a short operating life, and given the success of the incandescent light, Edison had little reason to pursue an alternative means of electrical illumination.
Although Edison lost interest in fluorescent lighting, one of his former employees was able to create a gas-based lamp that achieved a measure of commercial success. In 1895 Daniel McFarlan Moore (1869 - 1933) demonstrated electrically activated tubes 7 to 9 feet in length that used carbon dioxide or nitrogen to emit white or pink light, respectively. As with future fluorescent lamps, it was considerably more complicated than an incandescent bulb.
After years of work, Moore was able to extend the operating life of the lamps by inventing an electromagnetically controlled valve that maintained a constant gas pressure within the tube. Although Moore’s lamp was complicated, expensive to install, and required very high voltages, it was considerably more efficient than incandescent lamps, and it produced a more natural light than incandescents. From 1904 onwards Moore’s lighting system was installed in a number of stores and offices. Its success contributed to General Electric’s motivation to improve the incandescent lamp, especially its filament. GE’s efforts came to fruition with the invention of a tungsten-based filament. The extended lifespan of incandescent bulbs negated one of the key advantages of Moore’s lamp, but GE purchased the relevant patents in 1912. These patents and the inventive efforts that supported them were to be of considerable value when the firm took up fluorescent lighting more than two decades later.
At about the same time that Moore was developing his lighting system, another American was creating a means of illumination that also can be seen as a precursor to the modern fluorescent lamp. This was the mercury vapor lamp, invented by Peter Cooper Hewitt (1861-1921) and patented in 1901 (U.S. Pat. No. 889,692). As the name implies, Cooper-Hewitt’s lamp luminesced when an electric current was passed through mercury vapor at a low pressure. Unlike Moore’s lamps, those made by Cooper-Hewitt could be manufactured in standardized sizes and operated at low voltages. The mercury-vapor lamp was superior to the incandescent lamps of the time in terms of energy efficiency, but the blue-green light it produced limited its applications. It was, however, used for photography and some industrial processes.
Mercury vapor lamps continued to be developed at a slow pace, especially in Europe, and by the early 1930s they received limited use for large-scale illumination. Some of them employed fluorescent coatings, but these were primarily used for color correction and not for enhanced light output. Mercury vapor lamps also anticipated the fluorescent lamp in their incorporation of a ballast to maintain a constant flow of current.
Cooper-Hewitt had not been the first to use mercury vapor for illumination, as earlier efforts had been mounted by Way, Rapieff, Arons, and Bastian and Salisbury. Of particular importance was the mercury vapor lamp invented by Küch in Germany. This lamp used quartz in place of glass to allow higher operating temperatures, and hence greater efficiency. Although its light output relative to electrical consumption was better than other sources of light, the light it produced was similar to that of the Cooper-Hewitt lamp in that it lacked the red portion of the spectrum, making it unsuitable for ordinary lighting.
An electric current passing through a tube was the basis for another form of illumination, the neon light. While Moore used carbon dioxide, nitrogen, or atmospheric air to fill the tubes and Cooper-Hewitt and others employed mercury vapor, the next step in gas-based lighting took advantage of the luminescent qualities of neon, an inert gas that had been discovered in 1898. In 1909 Georges Claude (1870 – 1960), a French chemist, observed the red glow that was produced when running an electric current through a neon-filled tube. He also discovered that a blue glow resulted from the use of another inert gas, argon. The light could be used for general illumination, and in fact was used in France for this purpose beginning around 1930, but neon lighting was no more energy-efficient than conventional incandescent lighting, and it came to be used primarily for eye-catching signs and advertisements. Neon lighting was not irrelevant to the development of fluorescent lighting, however, as Claude’s improved electrode (patented in 1915) overcame “sputtering,” a major source of electrode degradation. Sputtering occurred when ionized particles struck an electrode and tore off bits of metal. Although Claude’s invention required electrodes with a lot of surface area, it showed that a major impediment to gas-based lighting could be overcome.
The development of the neon light also was significant for the last key element of the fluorescent lamp, its fluorescent coating. In 1926 Jacques Risler received a French patent for the application of fluorescent coatings to neon light tubes. The main use of these lamps, which can be considered the first commercially successful fluorescents, was for advertising, not general illumination. This, however, was not the first use of fluorescent coatings. As has been noted above, Edison used calcium tungstate for his unsuccessful lamp. Other efforts had been mounted, but all were plagued by low efficiency and various technical problems. Of particular importance for the story that was to follow was the invention in 1927 of a low-voltage “metal vapor lamp” by Friedrich Meyer, Hans-Joachim Spanner, and Edmund Germer, who at the time were employees of a German firm located in Berlin. A German patent was granted but the lamp never went into commercial production.
All the major features of fluorescent lighting were in place at the end of the 1920s. Decades of invention and development had provided the key components of fluorescent lamps: economically manufactured glass tubing, inert gases for filling the tubes, electrical ballasts, long-lasting electrodes, mercury vapor as a source of luminescence, effective means of producing a reliable electrical discharge, and fluorescent coatings that could be energized by ultraviolet light. At this point, intensive development was more important than basic research.
In 1934 Arthur Compton, a renowned physicist and GE consultant, sent a report to W.L. Enfield, manager of research and engineering at GE lamp department, outlining successful experiments with fluorescent lighting at the research laboratory of the General Electric Co., Ltd. in Great Britain (although it bore the GE moniker, this firm had no direct connection with General Electric in the United States). Stimulated by this report, and with all of the key elements available, a team led by George E. Inman built a prototype fluorescent lamp in 1934 at General Electric’s Nela Park (Ohio) engineering laboratory. This was not a trivial exercise; as noted by Arthur A. Bright, “A great deal of experimentation had to be done on lamp sizes and shapes, cathode construction, gas pressures of both argon and mercury vapor, colors of fluorescent powders, methods of attaching them to the inside of the tube, and other details of the lamp and its auxiliaries before the new device was ready for the public.”
In addition to having talented engineers and technicians along with excellent facilities for R&D work on fluorescents, General Electric controlled what it regarded as the key patents covering fluorescent lighting, including the patents originally issued to Cooper-Hewitt, Moore, and Küch. More important than these was a patent covering an electrode that did not disintegrate at the gas pressures that ultimately were employed in fluorescent lamps. This invention had been created by Albert W. Hull of GE’s Schenectady Research Laboratory, and was registered as U.S. Pat. No. 1,790,153.
While the Hull patent gave GE a basis for claiming legal rights over the fluorescent lamp, a few months after the lamp went into production the firm learned of a U.S. patent application had been filed in 1927 for the aforementioned “metal vapor lamp” invented in Germany by Meyer, Spanner, and Germer. The patent application indicated that the lamp had been created as a superior means of producing ultraviolet light, but the application also contained a few statements referring to fluorescent illumination. Efforts to obtain a U.S. patent had met with numerous delays, but were it to be granted, the patent might have caused serious difficulties for GE. At first, GE sought to block the issuance of a patent by claiming that priority should go to one of their employees, Leroy J. Buttolph, who according to their claim had invented a fluorescent lamp in 1919 and whose patent application was still pending. GE also had filed a patent application in 1936 in Inman’s name to cover the “improvements” wrought by his group. In 1939 GE decided that the claim of Meyer, Spanner, and Germer had some merit, and that in any event a long interference procedure was not in their best interest. They therefore dropped the Buttolph claim and paid $180,000 to acquire the Meyer, et al. application, which at that point was owned by a firm known as Electrons, Inc. The patent (U.S. Pat. No. 2,182,732) was duly awarded in December 1939. This patent, along with the Hull patent, put GE on what seemed to be firm legal ground, although it faced years of legal challenges from Sylvania Electric Products, Inc., which claimed infringement on patents that it held.
Even though the patent issue would not be completely resolved for many years, General Electric’s strength in manufacturing and marketing gave it a pre-eminent position in the emerging fluorescent light market. Sales of “fluorescent lumiline lamps” commenced in 1938 when four different sizes of tubes were put on the market. During the following year GE and Westinghouse publicized the new lights through exhibitions at the New York World’s Fair and the Golden Gate Exposition in San Francisco. Fluorescent lighting systems diffused rapidly during World War II as industrial manufacture, stimulated by wartime needs, gave rise to intensified lighting demands. The use of fluorescent lighting continued to spread in the years following the war, and by 1951 more light was produced in the United States by fluorescents than by incandescents.
What are the issues behind the Famous invention fluorescent Lamp?it is believed that a Filipino Inventor Agapito Flores invented the Fluorescent Lamp. but many controversies arises because of this renowned statements. according to research all the dates given are allegedly said to be wrong. How Did this Happen? Based on the history of the discovery of the fluorescent lamp the First discovery ways back into the 18th century where French physicist Alexandre E. Becquerel who had investigated the phenomena of fluorescence and phosphorescence, theorized about the building of fluorescent tubes similar to those made today.
2.merican, Peter Cooper Hewitt (1861-1921) patented (U.S. patent 889,692) the first mercury vapor lamp in 1901. The low pressure mercury arc lamp of Peter Cooper Hewitt is the very first prototype of today's modern fluorescent lights. 3. Edmund Germer (1901 - 1987) who invented a high pressure vapor lamp, also invented an improved fluorescent lamp. In 1927, Edmund Germer co-patented an experimental fluorescent lamp with Friedrich Meyer and Hans Spanner.
So What Is True About Agapito Flores?
Agapito Flores was born in Guiguinto, Bulacan, Philippines on September 28, 1897. He worked as an apprentice in a machine shop and later moved to Tondo, Manila where he trained at a vocational school to become an electrician.It has been reported that Agapito Flores received a French patent for a fluorescent bulb and that the General Electric Company bought Flores' patent rights and manufactured and sold his fluorescent bulb (making millions from it). However, all the inventors named above and more predate Agapito Flores' possible work on any fluorescent bulb.
According to Dr. Benito Vergara of the Philippine Science Heritage Center, "As far as I could learn, a certain Flores presented the idea of fluorescent light to Manuel Quezon when he became president. At that time, General Electric Co. had already presented the fluorescent light to the public."
