the machines and devices used in preparing illustration printing plates. Reproduction equipment may be photomechanical or electronic.
Photomechanical equipment is used for individual operations of reproduction, such as the preparation, retouching, and mounting of negatives and diapositives and the preparation and treatment of copies. Cameras suitable for photographing planar images are used to obtain negatives. Such cameras may be vertical or horizontal in design. Also available are large horizontal cameras suspended from the ceiling, which facilitate access to the surface on which the original image is projected (the screen), to the lighting equipment, and to the objective lens. All modern reproduction cameras have an electric drive, automatic focusing devices, and automatic light meters.
Diapositives, as a rule, are made from negatives in contactcopying machines, whose design is similar to that of the frames used in contact printing of photographs. Negatives and diapositives are retouched on special tables whose top has an insert of frosted glass and can be inclined to the required angle. Mounting is done on tables that have a glass cover illuminated from below by diffused lighting. The sensitizing of plates (the application of a light-sensitive layer on their surface) is done in vertical or, less commonly, horizontal centrifuges. The transfer of the image from the negative or diapositive to the sensitized plate is done in copying frames equipped with high-power sources of actinic light, such as arc lamps or xenon lamps.
Contact between the negative or diapositive and the copying layer is ensured by creating a vacuum inside the frame. The copies are usually treated manually in individual vessels or sinks. However, in large-scale offset printing it is possible to use automated flow lines consisting of a row of baths into which the copies are fed by a programmed delivery device. Etching machines of an enclosed type are used for etching prepared copies in letterpress printing. Such machines feed the solutions to the plate at the required rate.
Electronic reproduction equipment is extremely complex. It is capable of performing the whole series of operations. Hence, it is most efficient for reproducing multicolored images. To obtain color-separated diapositives or printing plates, electronic color separators and color correctors, which keep color distortions to a minimum, are used most frequently. The use of electronic devices eliminates the laborious production steps involved in photographing the originals and obtaining and treating the copies. As a result, the production of copies is simplified and drastically shortened and a high quality of reproduction is ensured.
REFERENCEGudilin, lu. N., and K. F. Izmailov. Oborudovanie dlia izgotovleniia pechatnykh form. Moscow, 1971. (Poligraficheskie mashiny, book 2.)
I. A. ZHUKOV