Electrophotography, more commonly known as xerography, is based on the
formation of a latent electrostatic image on an imaging surface by first uniformly electrostatically charging the surface of the imaging layer in the dark and then exposing this electrostatically charged surface to a light and shadow image
.
What type of ink is used by the electrophotographic process?
It uses
electrostatic charges, dry ink (toner)
and light. A selenium-coated, photoconductive drum is positively charged. Using a laser or LEDs, a negative of the image is beamed onto the drum, cancelling the charge and leaving a positively charged replica of the original image.
What is the principle of xerography?
As a photographic process, xerography employs
a re-usable plate consisting of a thin layer of a photo-conductive material on an electrically conductive base
. The plate is sensitized by electrostatic charging immediately before use. After exposure, the image is developed by dusting the plate with a micronized powder.
What is the first step of electrophotography printing?
An electrophotographic printer consists of six processes:
charging, exposure, developing, transfer, fusing and cleaning1
. For printing, charged toner, which is a coloring agent, is selectively transferred to the recording paper primarily by static electricity.
What are the major steps of processing of charging in xerography?
The basic xerography process makes uses of
electrostatic charge to create the image, to then use light from the image to remove charge selectively, and then apply a toner to the remnant charge
. The toner must be fixed to the paper using a thermal process. Figure 18.6. Printing/copying machine.
Is xerography still used?
Xerography is
now used in most photocopying machines
and in laser and LED printers.
Why is xerography used?
Xerography, also known as electrophotography, is
a printing and photocopying technique that works on the basis of electrostatic charges
. The xerography process is the dominant method of reproducing images and printing computer data and is used in photocopiers, laser printer s and fax machines.
What element is electro photography?
Suitable materials for the use in such systems include
anthracene, sulfur, and selenium
. In addition to anthracene, other organic photoconductive materials most attractive to PVK have been the focus of interest in electrophotography.
Is toner positive or negative?
Tiny particles of toner are pressed against the drum’s surface. The plastic-based toner particles have a
negative charge
and are attracted to areas of positive charges that remain on the drum’s surface. 6. The corona wire passes over a sheet of paper so that the paper’s surface becomes electrically charged.
How does toner acquire its charge?
As the developer is stirred and the particles rub up against each other, a triboelectric charge is generated between the them. The toner becomes
negatively charged while the carrier becomes positive
. The opposite charges cause the toner to be attracted to the carrier.
What are the 7 steps of the laser printing process?
- Step 1: Sending. To begin the laser printer process, the document is broken down into digital data and sent from the respective computer to the printer. …
- Step 2: Cleaning. …
- Step 3: Conditioning. …
- Step 4: Exposing. …
- Step 5: Developing. …
- Step 6: Transferring. …
- Step 7: Fusing.
What is the first step of the copy process?
A piece of paper is placed over the powder image and then given a positive charge. The negatively charged powder is attracted to the paper as it is separated from the photoconductor. Finally,
heat fuses the powder image to the paper
, producing a copy of the original image.
What voltage does the corona wire or corona roller hold?
A primary charge roller (or in some cases a corona wire) applies
between -500 and -1,000 VDC
to the imaging drum. This charge neutralizes the photosensitive surface of the drum and prepares it to receive an image. A highly focused laser shines light onto the imaging drum through one or more mirrors.
Where was xerography invented?
It is the text of the first xerographic image ever fashioned. It was created in
a makeshift laboratory in Queens, NY
. by a patent attorney named Chester Carlson, who believed that the world was ready for an easier and less costly way to make copies.
Which metal is used for xerography?
The first step of the process deals with the charging of a Photoconductor. In most printing applications the photoconductor is a metal drum that is coated with
amorphous selenium
and mounted to rotate around its axis. Selenium is used because it is able to hold and conduct charges in the absence and presence of light.
Which is used as photoconductor in xerography?
Selenium
is used as a photoconductor in Xerox (photostat) machine.
