Chester Carlson

Chester Floyd Carlson (born February 8, 1906 in Seattle , Washington , † September 19, 1968 in New York ) was a physicist and patent attorney . He is considered to be the inventor of the modern photocopier based on the principle of electrophotography . The term xerography (Greek for “dry writing”) is also used.

Life

Childhood and youth

Chester F. Carlson was the only child of Olof Adolph (* 1870, † 1932) and Ellen Josephine Carlson, b. Hawkins (1870--1923). Due to the incapacity for work of his father, who suffered from arthritis and tuberculosis , the family lived in dire poverty. In search of a healthy climate, the Carlsons often moved, but without the success they had hoped for. The family finally settled in San Bernardino , California around 1912 and little Chester started school.

Because of his poverty, the boy was an outsider at school who had little contact with his classmates. From the age of eight, Chester helped with small jobs to support his family. At the age of twelve, his day began at four in the morning: before school started, he worked two to three hours, cleaning shop windows and shops. After school, work went on, the boy rode an old bicycle from job to job. He helped with the harvest, sold soda water and raised guinea pigs for an experimental laboratory. He attended high school when he was fourteen. At the time, he was making around $ 60 a month and was the main breadwinner for his family.

Despite the great stress, Chester Carlson was a good student with a particular interest in science and literature. At the age of fifteen, he made the decision to become an inventor. He saw this as an opportunity to conquer the poverty of his family and at the same time to do something good for society. It was around this time that he began to write down his ideas in notebooks and diaries. He maintained this until the end of his life; all of his records are publicly available on microfilm in the New York Public Library .

The young Carlson was also interested in printing technology , which he had learned about as a cleaning assistant in a local print shop. Using a decommissioned, pedal-operated printing press, he published “The Amateur Chemist Press”, a magazine that he produced single-handedly and offered to his classmates interested in science by subscription. It was during this project that he realized how much work was required for the technical reproduction, and for the first time he began to think about simpler reproduction methods.

Chester Carlson's mother died of tuberculosis when he was seventeen, and Carlson had to take care of his sick father in addition to school and jobs. Still, he graduated from high school with good grades. Following the advice of his uncle Oscar, Carlson applied for a place at Riverside Junior College. There was a study program there in which the students alternated between studying and earning a living every six weeks. In this way, students from poor families could also pay their tuition fees. Carlson found work in a cement factory and moved his father into a one-room apartment in Riverside.

Studies and first professional experience

He initially majored in chemistry, but soon switched to physics. His professor Howard Bliss looked after Carlson intensively and supported the shy young man with advice and action. So Carlson managed to complete his undergraduate degree in three instead of four years. He then applied to the California Institute of Technology (CalTech) and was accepted there in the fall of 1928. He moved to Pasadena with his father and studied for two more years under difficult financial circumstances. When he made in 1930 his degree at CalTech, ruled the nationwide economic crisis and rising unemployment. Over 80 applications that Carlson sent in his last semester did not produce any results. But in the end he was lucky and in the spring of 1931 got a job as a research engineer at Bell Telephone Laboratories in New York City . Fortunately, his father's health had stabilized to such an extent that he was able to leave him in the care of a previous neighbor in San Bernardino. Carlson found a cheap ride and reached New York within a month.

He lived in Brooklyn for two years , first at the YMCA , then in a hostel and with his aunt Ruth in Passaic, New Jersey, always striving to keep his living expenses as low as possible in order to be able to repay his debts from his studies at CalTech. He eventually moved to New York, where he shared a one-room apartment with Lawrence Dummond, a reporter who worked at night for the Daily News .

Carlson found his work at Bell (he did quality checks on coal for phone mouthpieces) a dead end. Even during his studies he had noted in his diary that his clumsiness made him unsuitable for laboratory work. After a year he moved to the company's patent department, where he became assistant to a patent attorney. In this way he hoped to create a better starting point for his dream of becoming an inventor. During these years, he noted more than 400 ideas for inventions from all areas of daily life in his notebooks.

In 1932 Carlson's father's health suddenly deteriorated. He immediately took the bus to San Bernardino, but was late. His father had died the day before, so all he could do was arrange his funeral and dissolve the apartment.

Due to the economic crisis, his job at Bell was no longer secure and, like many other colleagues, he was laid off in the summer of 1933. That was a low point in his life. But Carlson didn't give up and asked all of the patent attorneys in New York for work. After six weeks he found a new job and after a year switched to P. R. Mallory, a well-known manufacturer of electrical and electronic components.

For the work in the patent department, many copies of texts and drawings were needed every day: the patent specifications were copied with a typewriter and carbon paper, the drawings were photocopied by service companies. Carlson recognized the need for a simple office copier without complex photographic procedures and finally concentrated his inventive work on solving this problem.

In the fall of 1934, Chester F. Carlson and Elsa von Mallon married. The couple moved into a small apartment in a house in Jackson Heights, Queens , that belonged to Elsa's parents of German origin. Carlson had finally paid off his debt, but his salary as a patent attorney's assistant was not high - and he now had to provide for two. In addition, his mother-in-law did not accept him. So for Carlson his plan to invent a new copying process became a kind of obsession, the ideal solution to all of his financial and family problems. But he was disciplined enough to continue his professional education, and from 1936 attended evening class at New York Law School to get his patent attorney diploma.

Development of the photocopying process

On weekends he studied legal literature at the New York Public Library (NYPL). Because he couldn't afford to buy all of these books, he copied long passages of text by hand. Again Carlson realized the relief a simple copying process would bring. The arduous study work was made difficult by typing cramps and back pain, from which he often suffered. It was during this period that he was concerned about the first signs of arthritis, the disease that made his father disabled. If the pain became too much while copying, then he would read everything he could find in the library about printing, reproduction and copying - always looking for ideas on how to put his idea of ​​a new copying process into practice.

More than a year passed in this way, but apart from a few fruitless attempts and many notes, Carlson had not achieved anything tangible, although he devoted most of his free time to solving the problem. He had dismissed the conventional photographic methods as unsuitable for a compact office copier, as well as his idea of ​​using a universal chemical solvent - yet to be invented - to make prints of documents in the copying press. He wondered if there weren't other reactions of light and matter than the well-known ones. Then he came across the book "Photoelectric Phenomena" in the NYPL and found the inspiration he was looking for in it: He would generate electricity through the action of light on suitable materials and use this for an electrochemical reaction to create copies.

His first attempt failed miserably: "I thought that if I brought a layer of photoconductive material into close contact with a chemically sensitized paper, the latter would discolor under the influence of the electrical voltage generated by light." But nothing happened. Carlson was disappointed - but he digged deeper into the complexities of photoelectricity and finally found out why this idea couldn't work. But he did not find a workable solution until he came across an article by the Hungarian physicist Pál Selényi (1884–1954) in a German scientific journal in which he reported on a method for the electrical transmission and recording of photographic images that he had already published in had developed in the late 1920s. Selényi called his invention "electrography" and described, among other things, a method with which he could make the images, broken down into electrical impulses for the purpose of remote transmission, visible again and transfer them to an image carrier. This invention gave Carlson the decisive impetus, as he himself often emphasized later.

He immediately began working out a copying process and designing a corresponding photocopier. On September 8, 1938, he applied for a patent for his process - he called it "electron photography" - and the photocopier. Unlike Selényi, who z. Carlson wanted to create a two-dimensional photographic reproduction in the form of an electrostatic charge image, for example by using guided ion emissions to “write” electrostatic charges line by line on non-conductive surfaces.

According to Carlson's patent specification (US Pat. No. 2,221,776), the imagewise exposure of a permanently installed thin layer of photoelectric material in the photocopier's camera was intended to release electrons that were "trapped" on the surface of the electrically non-conductive copy paper, developed and finally fixed there. As with Selényi, a fine powder was used for development, which was to be attracted by the electrostatic charge image on the copy paper and permanently fixed on it, for example by heat.

The advantages compared to the conventional photographic method were on the one hand the theoretically unlimited reusability of the photoelectric recording material and on the other hand the dry, rapid development and fixing of the copies. Another advantage was that no expensive silver salts were required.

Cooperation with Kornei and practical implementation

Carlson had made great progress, but he also knew that it would be difficult to find licensees for his process with just the patent specification. He would at least have to demonstrate his invention to potential interested parties - preferably with a working model. However, the production of the materials and the construction of the photocopier designed by him exceeded his technical and financial possibilities.

Carlson tried to solve these difficulties in two ways. He wondered whether there might not be an even simpler variant of the method he had devised. And he worked out exactly how much money he could raise each month for an experienced research assistant. Since he had previously carried out his experiments in the kitchen or in the basement, he would also have to rent a room for a laboratory.

The financial side was easy to calculate: $ 115 per month was his maximum spending. The simplification of his patented process was more difficult and basically only possible through experimentation. So Carlson started all over again, reconsidering everything he'd learned about photoelectricity. Suddenly he had a new idea: There are substances, so-called photoconductors, which are electrical insulators in the dark, but become electrically conductive under the influence of light. If he were to coat a metal plate with such a substance and charge it electrostatically in the dark, it would have to lose the charge applied during the imagewise exposure wherever the light hit the photoconductive layer. The charge would be retained in the dark areas of the original. The resulting electrostatic charge image could be made visible through a fine powder and transferred to paper.

Carlson immediately tried to put the new method into practice. As photoconductor he chose the inexpensive sulfur and as a basis cliché plates of zinc in the size of a business card. But he failed miserably just by coating the zinc plates with a thin and even layer of sulfur. The molten sulfur caught fire on the first try and the caustic fumes could still be smelled in the kitchen for days. The attempt to make a fine image powder from colored resin was somewhat more successful, but overall Carlson's efforts did not produce any presentable result.

The inventor was lucky in his search for a capable assistant: the physicist Otto Kornei (1903–1993) had worked as an electrical engineer in Vienna. He and his family had fled the Nazis from Austria to the USA and was urgently looking for work. Carlson was the only one who answered his job application. He presented his invention to Kornei and offered him the opportunity to assist with the further development of his copying process for six months for a monthly wage of 90 dollars. Even for the times that was little more than starvation wages, Kornei agreed in the hope of finding a better paid job during this time. Her contract gave Kornei 20 percent of the first $ 10,000 and 10 percent of all further income from the invention. In return, the rights to all possible improvements and follow-up inventions that Kornei made during his activity were transferred to Carlson.

On October 6, 1938, Kornei began working in the makeshift laboratory space in Astoria , Queens, that Carlson had rented from his in-laws for $ 15 a month. It was easy for Kornei to coat the zinc plates evenly with sulfur, and he showed Carlson how these could easily be charged electrostatically by friction. The first exposure attempts were already promising, and after the production of a fine dark picture powder from colored bear moss spores (Lycopodium) was successful, the two set the date for their first photocopying experiment to October 22, 1938.

That Saturday Kornei had prepared everything that was necessary. The sulfur layers on the zinc plates were smooth and evenly polished, a powerful Mazda photo lamp was ready for the exposure and a small pane of glass labeled with black ink served as a template: "10.-22.-38 ASTORIA" was written on by Kornei.

They darkened the room and Kornei rubbed the sulfur layer on the zinc plate vigorously with a cotton cloth for about half a minute. As a result of the friction, the sulfur surface became electrostatically charged and the plate became photosensitive. Kornei then placed the inscribed glass pane with the writing side on the sulfur plate and exposed it for about 10 seconds with the photo lamp. In this way he created an invisible electrostatic copy of the writing. From a test tube closed with a coarse-meshed material, he dusted the plate evenly with the fine image powder and then removed the excess powder by carefully blowing. The copied font became visible. Carlson placed a matching piece of wax paper on top of the powder layer and rolled it over the back with a small rubber roller. The image powder was pressed into the wax layer by the pressure. Subsequent gentle heating caused the powder to bond permanently to the wax paper and the first electro-photocopy was ready.

The result of the first attempt was far from perfect, but Carlson's idea worked exactly as he had anticipated. He and Kornei repeated the experiment several times to prove that the sulfur layer could be reused without any problems. On the same day, Carlson outlined a device with a rotating photoconductive drum that would continuously deliver paper copies of microfilm originals. The individual process steps of charging, exposure, development, transfer and erasure exposure were arranged around the drum. This concept was to be implemented for the first time in the 1950s in the CopyFlo printers from Haloid-Xerox. It was used in all xerographic office copier machines from 1960 and still forms the basis of digital electrophotographic copiers and laser printers today.

In the following months Kornei made further improvements to the process. He found new photoconductors such as anthracene and developed new processes for coating metal plates as well as new image powders (toners) made from colored natural resins. By adding lithographic chalk to the toner, it was possible to make copies that could serve as paper printing plates for office offset printing. But Kornei also described in his laboratory diary how unpredictable the process was: in high humidity, the photoconductors could not be charged evenly by friction. The picture powders tended to be electrostatically charged unintentionally and also quickly became lumpy.

In March 1939, after the agreed six months, Otto Kornei accepted a position at the Brush Development Company in Cleveland. Shortly thereafter, on April 4, 1939, Carlson filed his second (or possibly his third, see above) patent (US Patent No. 2,297,691), with which he protected all potential uses of his invention, now called "Electrophotography". Just before Kornei moved to Cleveland, he asked Carlson to give him the rights to one of his inventions that he had made in Astoria just before his contract expired. In return, he wanted to forego the income he was entitled to (see above) from electrophotography. Carlson agreed and the two remained on friendly terms.

The search for licensees

Carlson finished his evening course a little later and was now trying to market his invention. He met with little interest, but some of the 20 or so companies he had contacted invited him to give a demonstration of his invention. For such demonstration purposes Kornei had put together all the necessary materials. The demonstrations essentially corresponded to the Astoria experiment and did not bring the desired success. Obviously nobody recognized the potential of electrophotography and the shy, introverted inventor did not succeed in convincing his interlocutors.

After numerous failures, Carlson planned to put the benefits of his invention in the right light with a functioning copier model. On November 16, 1940, he filed his patent application for an electrophotographic office copier, a desktop machine the size of a typewriter. In the same month his second patent was granted and a brief review of his invention appeared in the New York Times. A senior IBM employee then contacted Carlson and asked for a demonstration, which, however, also had no tangible result. In a letter, the inventor offered IBM an exclusive license for only $ 10,000.

Because Carlson had mentioned his model at the first demonstration, he was asked to give another demonstration with it. He had already commissioned a model maker, but he was unable to deliver a functional device and another model maker could not compensate for the construction-related deficiencies in his design, according to David Owen. The model had cost Carlson a lot of money, was visionary in many ways, but unsuitable for really convincing demonstrations. He couldn't invest any more money and so negotiations with IBM and other companies came to a standstill in 1943. In the same year Carlson separated from his wife Elsa, and the two divorced in 1945. Since he had meanwhile become the head of the patent department at PR Mallory, he had even less time to develop his invention further.

Further development by the Battelle Memorial Institute

When Carlson met Russell W. Dayton, an engineer at the Battelle Memorial Institute in Columbus, Ohio, at P. R. Mallory in 1944, he happily told him about his invention and gave him a copy of his patent specification. A few weeks later Dayton asked him to demonstrate his invention at the institute. This time the response to Carlson's demonstration was positive. The scientists present immediately recognized the diverse possibilities of electrophotography: Roland M. Schaffert, head of the "Graphic Arts Group" at the institute, campaigned for Battelle to research and develop the process, and in autumn 1944 Carlson and Battelle signed a license agreement. Carlson was to receive 40 percent of all income from his invention. The renewed search for licensees was again unsuccessful.

This changed in 1945: Nicolas Langer, a Hungarian patent attorney and inventor, had become aware of Battelle's invention in early 1944 - even before Carlson's negotiations with Battelle - and had published a report on it in the magazine “Radio News”. A summary of his article appeared in an Eastman Kodak bulletin eight months later. This article came across John Dessauer, head of research at the Haloid Company, a medium-sized manufacturer of photo papers and Rectigraph photocopiers in Rochester, New York - where the industry giant Kodak was also based. Joseph C. Wilson, the young CEO of Haloid, was looking for new products. He wanted to make the company independent of the competition with Kodak. Wilson was immediately interested and traveled with Dessauer to the Battelle Institute. What they saw there convinced them. After further meetings and discussions, Wilson signed a license agreement with the Battelle Institute in December 1946. This allowed Haloid to develop and market electrophotographic copiers for an annual license fee that should deliver less than 20 copies per minute.

In the fall of 1945 Carlson met his future wife Dorris Helen Hudgins (1904–1998), and the couple married in early 1946 - it was their second marriage. Carlson quit his position at P. R. Mallory in late 1945 and worked as a freelance patent attorney for about a year before setting up his own company with Dorris as his secretary.

The development work on electrophotography was carried out exclusively at the Battelle Institute in 1947 and 1948. Through Joseph C. Wilson's contacts with the US Army Signal Corps , he was able to get his first research contract worth $ 100,000 in 1948. Three years after Hiroshima and Nagasaki, the US Army was looking for a photographic process that, in contrast to conventional photography, would also work in radiation-contaminated areas.

The intensive research now possible also led to significant advances in the area of ​​office copying. The most important step was the discovery of amorphous selenium as a photoconductor by Battelle physicist William Bixby. Amorphous selenium is a thousand times more sensitive than sulfur or anthracene. This made it possible for the first time to expose the photoconductor using a reproduction camera - and thus also to optically enlarge or reduce the size of originals using electrophotography. A xerographic instant camera, the so-called “One-Minute-Minnie”, was built for the Signal Corps.

First public presentation of xerography

Haloid had converted the contract with Battelle into an exclusive license in 1948. The company decided to publicize its commitment to Carlson's invention - together with the Battelle Institute. The annual meeting of the Optical Society of America was chosen as the platform. This should take place on October 24th in Detroit - two days after the tenth anniversary of the Astoria experiment by Carlson and Kornei. Since "electrophotography" appeared to be too technical as a name for the process on the one hand and not too revolutionary on the other, a new name was sought. A Battelle public relations officer asked a professor at Ohio State University for advice. He suggested using the Greek words for “dry” and “writing” to create the made-up word “xerography”.

During the demonstration in Detroit, the individual steps of xerography were demonstrated in separate stations by the participating scientists and engineers. The production of a xerographic copy took just under a minute and the demonstration was a journalistic success. In the months that followed, Haloid worked flat out to complete the first xerographic office copier. It took around a year for the first copies of the device, dubbed “XeroX Model A”, to be completed. "XeroX" has been registered by the Haloid Company as a brand name for the xerographic products. The employees nicknamed the box-shaped photocopier "Ox-Box". (Image reference?) Integrated into the apparatus (from top to bottom) were the exposure by means of fluoroscopy of the original, the corona unit for charging the selenium plates and the development unit. The corona unit was again used to transfer the toner image from the selenium plate onto simple writing paper. The resin toner was fixed on the paper in a separate small heating furnace.

To make a photocopy with the Ox-Box, you put the original with its back on the platen glass. All kinds of translucent line art, such as letters, invoices or drawings, but no books or surfaces, could be copied. Then a selenium plate was pushed into the corona unit, electrostatically charged and sealed light-tight with a slide. The plate was mounted in the exposure unit above the original and the slide removed. After the exposure unit was closed, the original was in close contact on the selenium plate. The exposure was triggered by pressing a button - this could be adjusted to different templates using a timer. The exposed plate was closed again, removed and now attached to the developer trough. After the light protection was removed again and the plate firmly locked, the trough was slowly rotated several times around its axis so that the mixture of toner and developer (coated grains of sand or glass beads) slid over the surface of the selenium plate. This developed the electrostatic charge image. The selenium plate was removed and pushed a few centimeters into the corona unit. Then a sheet of writing paper was carefully placed on top of the toner image, the transfer button was pressed and the plate was slowly pushed into the slot of the unit. The corona now charged the back of the paper electrostatically. This transferred the toner to the paper. In the separate fusing unit, the thermoplastic toner powder was fused with the paper at around 180 degrees Celsius and the xerographic copy was ready.

Failure as an office copier technology

In order to test the market acceptance of the new photocopier, Haloid set up the devices for free at several companies for testing. The result was devastating. All companies returned their “XeroX Model A” after a short trial period: too complicated and too tedious for office use, was the unanimous verdict. Haloid owes the fact that this beginning did not also end xerography to the fact that the Model A could also be used to produce paper printing plates for office offset printing. Carlson and Kornei had already foreseen and tested this. Since at that time many companies were copying larger editions with an office offset machine and the creation of the printing foils was time-consuming and costly, there was a market that Haloid had not anticipated. And in this market the XeroX machine was without competition. There was no faster, cheaper way to make paper printing plates. With the profits from this market segment, Haloid received a good basis for the further development of xerography. And also Chester Carlson, who had been employed by Haloid as a patent attorney since 1948, earned more money for the first time with his invention than he had invested in all the previous years.

In 1953 Haloid launched the "Model D", a device optimized for the production of printing plates, which was sold until the 1970s. With the optionally available "Camera No. 1", double-sided originals and books could be copied 1: 1 and with the "Camera No. 4" it was also possible to continuously enlarge and reduce, but still manually, as with model A.

The first xerographic machine was not an office copier, but a re-enlargement device for microfilm: In 1954 the "XeroX CopyFlo 11 Printer" was introduced, it produced around 30 pages per minute on normal paper. For the first time a selenium drum was used as a photoconductor - all processes could thus run continuously, as Carlson had already intended in the patent specification of his model.

Carlson had pushed through the establishment of an independent patent department at Haloid in order to have more time to solve technical problems. He was actively involved in the further development of xerography at Haloid until the mid-1950s and received numerous other patents. In 1955 he was appointed chairman of the company's "Small Copier Committee". This committee was supposed to critically consider and assess the plans for the development of the first fully automatic xerographic office copier. The verdict was positive and the engineers started work.

At the same time, the management was negotiating with the Battelle Institute to change the license agreement. For 53,000 Haloid shares and a three percent profit participation by 1965, Haloid received the entire rights to the xerography. Since Carlson had assigned the rights to his invention to Battelle in 1944 in return for a 40 percent share of all proceeds, he was now entitled to 21,200 Haloid shares plus a 1.2% annual profit participation. This would become the basis of his later wealth.

Haloid's CEO Joe Wilson wanted the company's commitment to xerography, which made up 40% of its revenue in 1956, to be reflected in a change in the company's name. He suggested choosing the previous Xerox brand name as the company , but met with great resistance from the board of directors and shareholders. As a compromise, the company was renamed "Haloid Xerox" in 1958. The name was changed to Xerox Corporation only three years later.

Chester Carlson has always been described by his colleagues at Haloid as a considerate, patient, and reserved person who was totally absorbed in his work. He didn't like being in the foreground and only took part in technical discussions during the lunch breaks. During his first marriage he had practically only lived for his invention, but his second wife Dorris changed his life and Carlson turned increasingly to metaphysical ideas and topics such as rebirth and Far Eastern religions.

By selling the license to Haloid, the Carlsons were financially independent for the first time in 1955 and were able to support their modest lifestyle from the growing income. Carlson resigned from his position at Haloid but remained a consultant for the company until his death. He continued to work on xerography improvements at home and loved working in the garden of their little house outside of Rochester in his spare time.

The first copier

The development of the copier was completed at the end of 1959. Six devices were set up at local companies as a trial to test market acceptance. Unlike the "Model A", this time no company wanted to return the device. In February 1960 the first 50 machines were completed and delivered. Five copies of the “Xerox 914” (it produced five copies per minute up to the format 9 × 14 inch) named automatic copier were completed daily. The Xerox 914 could not be bought, but rented for $ 95 a month - 2,000 copies were included, 5 cents for each additional copy. The developers had designed the machines for a maximum of 10,000 copies per month. That seemed more than sufficient. But the acceptance of the new technology exceeded all expectations from the start: many customers made an average of 40 to 50,000 copies per month. To relieve its service technicians, Haloid offered these customers every additional Xerox 914 for just $ 25 a month. The production rate grew to 25 units per day and the small company Haloid Xerox struggled to keep up with the ever-increasing demand.

The first xerographic copier became the most successful industrial product of its time. But not only the entire office communication was revolutionized by the Xerox 914: In the following years the copier became an important and soon indispensable communication tool in science and research, in libraries and in education. In view of these effects, Marshall McLuhan put Chester Carlson's invention on a par with that of Johannes Gutenberg in “The Medium Is the Message” (1967): “Gutenberg turned people into readers, Xerox turned them into editors.”

An anonymous benefactor

Until 1965, Carlson benefited directly from the boom in xerography. The value of Xerox stock rose forty-fold from the early 1960s. He grew exceptionally wealthy and received numerous honors, but maintained his humble lifestyle. He found a new task in the distribution of his wealth that would keep him busy for the rest of his life. He did everything himself, weighed every request personally and donated large sums for racial integration, for pacifist organizations, for the promotion of democracy. He sponsored universities, schools, hospitals, libraries. For example, he had a physical chemistry research center built at CalTech and funded parapsychologist Ian Stevenson's research on reincarnation , for which he endowed a chair at the University of Virginia.

The only condition that Carlson imposed on all of his donations and endowments was absolute anonymity: he did not want his name to be mentioned, but rather devoted himself to the distribution of his assets in camera. Of his wealth estimated at $ 150 million, he is said to have donated over 100 million to charitable causes.

It was through Dorris that the scientist and researcher Carlson discovered new areas of research for himself: in the 1960s, he took part in scientific experiments on dream research and telepathy as a test subject. Together with Dorris he studied the writings of the Vedas and Buddhism, both of which represent the doctrine of rebirth. And he developed a deep faith that he only spoke about with his wife and closest friends.

Due to the great success of the Xerox 914, Carlson was often invited to give lectures abroad and made numerous trips to Europe, Russia and India. Since Dorris didn't like to be out and about, he mostly traveled alone.

In the spring of 1968 - while on vacation in the Bahamas - he suffered a heart attack. Dorris took him to a clinic which he could not leave for three weeks. He recovered and went back to work. In September he went to New York City with Dorris. On the afternoon of September 15th, between two appointments, he was watching the English comedy "He Who Rides a Tiger" in a cinema. After the end of the film, the usher tried to wake the supposed sleeper, but Chester F. Carlson died during the film at the age of 62. Dorris organized a small private funeral ceremony for her husband on site, the big official funeral service took place on September 26th in Rochester.

After Carlson's death, Dorris continued his charitable work with Catherine B. Carlson, who she adopted. Catherine had known the Carlsons since the mid-1950s and was a good friend of the couple. Dorris Carlson died in 1998 at the age of 94. Today Catherine heads the Chester and Dorris Carlson Charitable Trust, with which she continues the philanthropic work of the two deceased.

Chester Carlson and Otto Kornei's "original xerographs" and Chester's copier model are in the Smithsonian Institution in Washington DC - Chester's collected records belong to the New York Public Library and can be viewed on microfilm there and in the University of Rochester library.

Even today, 60 years after the introduction of xerography, the technology invented by Carlson is used in almost all larger automatic copiers. But now in digital form, as laser or LED printing in black and white or color. Digital xerographic color printing has been able to compete with offset printing in terms of quality for years, but in comparison it offers a previously unknown degree of flexibility. The office copier machines of 1960 have now become real communication centers that send and receive documents, distribute and archive electronically, print them out as bound books and still photocopy them at the push of a button. The fact that we can no longer imagine doing without a photocopier is a sure sign that Chester F. Carlson changed the world with his invention.

In 1942 Carlson was granted US Patent No. 2,297,691 for the process called electrophotography . In 1968 he was elected to the American Academy of Arts and Sciences .

literature

• David Owen: Copies in Seconds - Chester Carlson and the Birth of the Xerox Machine . Simon & Schuster, New York 2004, ISBN 0-7432-5117-2
• Klaus Urbons: Chester F. Carlson and Xerography . Self-published, 2008.
• Strokes of Genius (XX): How Chester Carlson Invented the Copier . In: Die Zeit , No. 24/1996

Web links

• Mark Crawford: Chester Floyd Carlson Biography. ASME.org, April 2012 . 
• "Happy Birthday Xerography" (animated slide show about the exhibition "Who was Chester F. Carlson? - 70 years of xerography" in the Mülheim an der Ruhr office museum)
• Photos from the exhibition “Who Was Chester F. Carlson? - 70 years of xerography ”in the Mülheim an der Ruhr office museum

References and comments

1. ↑ He may have filed a provisional patent application a year earlier. See David Owen, Copies in Seconds , 91.
2. ^ Patent from October 6, 1942