Quick copy
The flash copy or copyrapid is a photocopying process that was invented by Edith Weyde at the Agfa company in the 1940s . The copiers based on this “method for the accelerated production of a photographic positive image from a template” were marketed with great success , especially by the company Develop .
Photography, photocopy, diffusion photocopy
An early method of making an image was photography . A negative , initially a light-sensitive coated glass plate, was exposed to light. The negative was developed in one bath, fixed in another bath and then dried. The result was an image in which light parts of the image appeared dark and dark parts of the image appeared light (tonal value reversal).
The negative was exposed using a camera (photography) or using the transmitted light method (photocopy), in which the original image was in direct contact with the negative. From this negative, a positive image could be produced in the same way, with an image identical to the original, preferably on coated paper, being created by another tonal value reversal. This method was used for the production of documents e.g. B. hardly suitable as a quick office copy. In photography, this process was very successful in an improved form ( roll film , slide) until the introduction of digital photography.
invention
The chemist Edith Weyde , who works for the company Agfa Aktiengesellschaft für Photofabrikation Leverkusen, observed blurred negative images of the front of photo prints on the back of criticized photo prints. Weyde found the cause to be a diffusion of unexposed silver from the photo prints, which were brought in a stack from the developer bath directly into the fixer bath. The unexposed silver image was thus able to detach from the photo prints, which were still damp from the developer, and diffused into the back of the paper of the prints adhering to them. This is also where the fixation took place. This formed a blurry negative. Edith Weyde realized that this diffusion could enable a simultaneous development of negative and positive.
Such a procedure would save an enormous amount of time. She succeeded in making the process usable professionally. In 1941 Agfa was granted a patent for the process.
functionality
The less sensitive and high-contrast black and white negative paper could be processed in subdued daylight. It was placed under the document to be copied with the light-sensitive side up. Both papers were pressed together with a lid. The exposure was through the negative. The reflection of the original produced a latent negative image of the document on the negative. The negative paper was then passed through a developer bath together with a positive paper and pressed together by means of motor-driven rollers. After a short waiting period during which the diffusion took place, the two papers could be separated from one another. A negative and a positive image became visible.
Restriction
The process could only produce black and white copies. Gray tones were only reproduced to a limited extent.
marketing
After the currency reform in 1948, Walter Eisbein, co-owner of the Trikop company from Stuttgart, in coordination with Agfa, quickly presented his developer called “ Develop ”. Other companies, for example Dr. Böger KG., Later Lumoprint Zindler KG. started the production of these development devices under license. Devices that combined a developer unit and an exposure unit were particularly successful. These initially misshapen, but already office-suitable devices were mainly made of wood covered with artificial leather. The exposure part essentially consisted of a box-shaped part adapted to the original format, on the bottom of which four or six commercially available light bulbs were arranged. At a distance above was a glass plate for the negative and the document to be copied. In front of the exposure part was the developer part with the developer liquid and the motor-driven rollers arranged above it.
Due to the success of the process, which quickly became known as "Blitzkopie", other companies entered the market, for example in 1959 the company Ravenna Bürotechnik, based in Borgholzhausen. In 1961, engineer Werner Knoop developed the office copier made of plastic, which was inexpensive to manufacture and which, thanks to the special arrangement of numerous low-voltage festoon lamps, allowed optimal light distribution and thus a very flat design. In connection with an automatic filling and emptying system for developer liquid and an electronic automatic exposure system used for the first time, the device became a best seller at the Hanover Fair in 1965.
Displacement through new processes
From the end of the 1970s, new copying processes increasingly replaced the diffusion copying process. Only for the production of offset printing matrices could it hold its own for some time. This is where the patented offset immersion diffusion process developed by Ravenna Bürotechnik was successful.
After that, xerography and digital photocopy ( electrophotography ) became dominant in the market and largely supplanted diffusion photocopy .
Individual evidence
- ↑ Silver salt diffusion process. In: Universal Lexicon. 2012, accessed March 18, 2016 .
- ^ Develop: Chronicle. Retrieved March 18, 2016 .
- ↑ Karsten Lemm: Breakthrough without breakthrough. Stern, October 21, 2008, accessed March 18, 2016 .