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7. Language note. Compounds.

Compound words can be formed in different ways. It is the combination of two words referring to one person, thing or action. There are many examples of such words in English and many new terms that enter the language are generated in this way. It is important to point out that such compounds are usually spelt as two separate words (computer program), but can also be one word (photoconductor) or hyphenated (drop-on-demand). Complete the list of compounds from the text:

short-run job, sheet-fed printing, web-fed …….

8. Write down 10 sentences of your own with compound words.

9. Correct the jumbled sentences:

  1. In, technologies, NIP, there, no, is, plate, printing, permanent, carrying, information.

  2. In, the, process, ink jet, the, is, ink, transferred, directly, substrate, to, the, by, a, jet, means, of, system.

  3. Ink jet, work, technologies, with, inks, liquid, low, of, as, viscosity, well, as, called, so, inks, hot-melt.

TEXT 2

Non-impact printing technologies

There is a number of non-impact printing technologies. They must be discussed in detail.

Electrophotography

Electrophotography is the most widespread non-impact printing technology. It is based on an invention by Chester Carlson. Electrophotographic printing process can be broken down into five steps:

1. Imaging

Imaging is carried out by charging a suitable photoconductive surface (creating a homogeneous charged surface) with subsequent imaging via a controlled light source (this may be scanning laser light or light emitted by an LED array [light-emitting diodes]). The print image corresponds to the positioning of the light signals on the photoconductor drum. The homogeneous charged image on the surface is discharged in parts as a result of exposure and changed in accordance with the desired print image. (Since imaging in electrophotography can be done both by laser light and by light given off by light-emitting diodes, the frequently-used term “laser printer” instead of the term “electrophotographic printer” is misleading.)

2. Inking

Special inks are used for electrophotography. These may be powder or liquid toners, which may vary in structure according to their composition, and contain the colorant in the form of pigments. The ink is the fundamental and decisive element for the impression. Inking is done via systems which transfer the fine toner particles without contact to the photoconductor drum. The toner charge is configured in such a way that the charged areas of the photoconductor surface accept the toner. After inking, the latent image on the photoconductor drum becomes visible where the toner is applied.

3. Toner transfer (printing)

The toner may be transferred directly onto the paper, although in some cases it may also be transferred via intermediate systems, in the form of a drum or a belt. Transfer mostly takes place directly from the photoconductor drum to the substrate. To transfer the charged toner particles from the drum surface to the paper, electrostatic forces are generated via a charge source (corona) in the nip and it is these forces, supported by the contact pressure between the drum surface and the paper, that transfer the particles to the paper.

4. Fixing the toner

A fixing unit is required to anchor the particles of toner on the paper and create a stable print image. This is usually designed so that melting and consequent anchoring of the toner on the paper takes place by heat application and contact pressure.

5. Cleaning

Residual charges and individual particles of toner remain on the drum after the print image has been transferred from the photoconductor drum to the paper. To prepare the drum so that the next image can be printed, both mechanical cleaning and electrical cleaning of the surface are necessary. The mechanical cleaning, which removes particles of toner, can be done by means of brushes and/or suction, while the electrical cleaning (neutralizing) is accomplished by homogeneous illumination of the surface, after which the surface is electrically neutralized and is free from toner particles. The photoconductor drum is now charged again with a homogeneous, charged image via the corona, with subsequent imaging in accordance with the desired print image.

With electrophotography and non-impact printing technologies in general, greater fluctuations can occur within the run than in the case with technologies requiring a printing plate.

Рис.6