Vincent Bonin © 2007 FDL
Name of tool: Haloid Xerox
Alternative name: Haloid
Inventors/Designers: Chester Carlson
Marketed by: Haloid
Design date: 1938 (approximate)
Marketing date: 1950
Type of application: Electrophotography copying
In the 1930s, physician Chester Carlson began researching electrostatic reproduction techniques. After a number of unsuccessful attempts with a variety of companies (including IBM), Carlson partnered with Haloid (which became Xerox Corporation) to develop a compact, easy to use copier. On October 22, 1948, the invention of the xerography process was announced to the public. Haloid began marketing the first model of its copier in 1950.
Brief list of components
Selenium plate; three independent modules: 1. “darkroom” module equipped with a photographic lens (camera); 2. processor; 3. fuser. Printing materials: silver oxide powder, chemically untreated paper.
Haloid’s xerography process involved the operator manually executing five successive steps. The operator would first remove the selenium plate from its protective envelope and place it into the processor chamber, where it would receive a positive electric charge (b). The plate was then slid into an ad hoc cartridge in the darkroom in order to absorb a latent (invisible) image from the source being copied. Haloid offered two darkroom models during the 1950s. The first (Model 1 camera) resembled the main component of a familiar office photocopier (c). The lens and lamp were located in a closed box equipped with a transparent exposure surface on which was placed the source. Only a 1 = 1 reproduction of the image could be produced. The second model (Model 4 camera) was comprised of an open structure similar to a photographic duplicating bench, which allowed the source to be enlarged by 150% or reduced by 50% (a). Once the plate was exposed, it was necessary to insert it back into the processor chamber and trigger the mechanism to disperse silver oxide powder. The powder would adhere only to those zones on the plate that had little or no exposure to the light when the image was captured (with the clear zones repelling the powder). To transfer the image, a sheet of paper (receptor) was placed on the plate, which was slid for a third time into the processor chamber (d). Upon receiving a positive charge, the paper would attract the negatively charged powder. The final step consisted of permanently fixing the resulting image to the receptor by laying the sheet against the surface of the heat fuser.
Effects and functionalities
Black and white copies that reproduced the grey scale of an original document.