SMART DIGITAL

Glossary D   E   F   G   H



D

data stream
Coded information that is sent from a host computer or storage device to the printer. Data streams include Adobe’s PostScript, Hewlett-Packard’s PCL, IBM’s IPDS, and Xerox’s Metacode.

demand publishing
See print on demand.

developer
In electrophotography, the developer is a consumable that acts as a charging agent. It has magnetic properties that allows it to carry toner particles until they are transferred to the photoconductive drum or belt. It may also be called carrier. In mono-component systems, the toner and developer are mixed together (in desktop laser printers, for example). A dual-component system (like the Xerox DocuTech) keeps the toner and developer separate.

device independence
For printing, device independence refers to the ability of a device to print an electronic file on a wide variety of devices low resolution or high resolution, black & white or color – and yet print to the best ability of any one of them. PostScript is device independent. A PostScript job may be printed on a black & white laser printer or inkjet color proofer, films may be output on an imagesetter, plates may be output on a platesetter, or the job may even be imaged on a digital press. All of this is possible as long as the file is PostScript, and all the devices are PostScript-compatible.

dielectric cylinder
An electrostatically charged imaging cylinder that is a component of electron beam imaging systems. See electron beam imaging.

dielectric paper
Specially-treated paper used in the electrostatic printing process, consisting of a conductive base layer coated with a non-conductive thermoplastic material.

digital
A process that is stepwise in nature, like the display of a digital watch (as opposed to an analog process, like the movement of the hands of a wristwatch). Within print-on-demand, the term may be used to describe the difference between analog photocopiers (which use lenses and reflected light to copy a document) and digital copiers (which actually scan the document).

digital copier
A digital copier uses a scanner to scan and then reproduce hard copy documents. (In contrast, an analog photocopier uses lenses and reflected light to copy a document.) A digital color copier attached to a color server becomes a network color printer.

digital duplicator
A duplicating machine that uses a thermal head to create a stencil from digital data.

digital press
A high-speed electrophotographic (laser or LED) printer capable of processing and outputting digital files; because of their speed, print quality, and paper handling capabilities, digital presses are able to print jobs traditionally done on offset presses.

digital printing
Any printing method in which the image is printed to paper or another substrate directly from a digital file.

digital proofing
Producing proofs directly from stored digital information without using film.

digitize
To convert an image or other data into a digital representation that may be processed electronically. You digitize a photograph when you scan it.

diode
A light source for creating a latent image on a photoconductive system. Example: a laser diode in an electrophotographic printer. See electrophotography.

direct to substrate
A printing process, like inkjet or thermal transfer, in which pigment is applied directly to the substrate.

direct to plate
A process in which a digital imaging system images printing plates without the use of intermediate film.

direct to press
A printing process in which a digital imaging system images printing plates that are pre-mounted on the press.

distribute and print (distributed printing)
Electronically distributing a file and then physically printing the job near the point of final delivery.

downtime
The interval during which a system or a single device is malfunctioning or not operating due to mechanical or electronic failure or between tasks.
See mean time between failures.

DPI
Dots per inch. Unit of resolution applicable to raster devices including printers and CRT’s. Devices can have different horizontal and vertical resolutions.

dry offset
See waterless offset.

duplexing
The ability to print on both sides of a sheet of paper without manual intervention. Duplexing is also referred to as “perfecting.” Some devices print both sides simultaneously using multiple print engines. Others flip and redirect the paper so that it passes the print engine twice.

dye sublimation
A printing process that uses a thermal print head to create color images from a digital file. Dye sublimation printers are often used for color proofing.





E

electron beam imaging
A process in which an electrostatically charged cylinder attracts an iron oxide toner to create the image.

electronic
Describes the use of electricity by a device such as a computer or a television set. Electronic devices used to employ vacuum tubes to control the flow of electrons but now use semiconductors. In current computer jargon, the terms “digital” and “electronic” are used almost interchangeably to describe computer oriented devices (i.e., digital or electronic files, digital or electronic prepress systems, etc.).

electronic collation
Ordering the pages of an electronic document so that they print in the proper order. This becomes more complex with duplex systems that can fit multiple pages into the image area.

electronic document interchange (edi)
Electronic document interchange is a standard for the transfer of documents between systems. The form and format of EDI-compliant documents may be defined by vendor specifications or by a variety of standards boards.

electronic overlay
A collection of constant data (known as a “form”) that is electronically composed in the host processor and may be merged with variable data on a sheet during printing.

electronic reprographic print on demand
The process of RIPping or scanning a document once and then printing multiple identical copies of that document.

electrophotography
The printing or copying process of using an electric charge to create an image on a photo-conductive surface. Toner is attracted to this surface, and later transferred to paper and fused.

electrostatic printing
A printing process that uses an electrostatic charge to create a latent image. Electrostatic printers are often used in large format posters and outdoor displays.

engine
The printing components of a laser printer, sometimes called the marking engine or the print engine. Example: the Apple LaserWriter and Hewlett-Packard LaserJet printers use a Canon engine.

eps
Acronym for encapsulated PostScript. An EPS file contains text and data. EPS files can easily be printed by many different software applications. An EPS file has two parts: a low-resolution bitmap for monitor display and a resolution-independent description of the image for printing.





F

fanfold
See continuous form.

feet per minute (fpm)
Measure of the speed of roll-fed printers.

fibre distributed data interface (FDDI)
A high bandwidth (100 megabits/second) optic network capable of transmitting data, images, and sound.

fixed-image plate system
An imaging process in which a master image on a disposable or removable plate is used to print multiple copies of a page. Every page is identical until a new plate is mounted on the system. Contrast with re-imageable systems.

free sheet
Paper containing 10% or less groundwood pulp.

front-end system
A computer system which handles a variety of non-printing tasks, including electronic page composition, file storage, and document management and ordering.

FTP
File Transfer Protocol.

fuser
The part of the printing system that forces the toner to adhere to the paper. There are several types of fusing systems (heat, chemical, and pressure).





G

gigabyte (GB)
1,024 megabytes (MB) of digital data.

gloss
A shiny or lustrous appearance on a sheet of paper that is most often due to a coating.

grade (paper grade)
A generic system of classifying papers by common characteristics or composition. There are hundreds of paper grades which fall into broad categories including newsprint, printing and writing papers, packaging and industrial papers, and tissue papers. Print-on-demand papers fall under printing and writing papers and include uncoated groundwood, coated papers, uncoated free sheet papers, thin papers, cotton fiber papers, and bleached bristol.

grain
The dominant direction of the fibers in a sheet of paper. Paper tends to fold easier if the fold runs parallel to the paper grain.

groundwood paper
Papers made from mechanical pulping processes which leave many natural impurities in the paper. See newsprint.

GSM
Grams per square meter.

halftone
The process of simulating a continuous tone (contone) image with tiny dots of varying size or position.

hard copy
Output in permanent, physical form. Examples include film, plate material, proofs, and documents printed on paper or other substrates. See soft copy.





H

highlight color
Printers that can produce various shades of one color (other than black) on a document.

host processor
A processor that controls all or part of a user application network, or LAN. The processing unit to which printers are attached through a data transfer interface.

HTML
Hypertext Markup Language.

HTTP
Hypertext Transfer Protocol.