Basic Copier Operation explained
This page will hopefully de-mystify the internal workings of your basic copy machine.
Even though a photocopy machine is a fairly complicated machine, most maintenance and
repairs are easily accomplished once you learn the major components and understand their
function.
The Basic Copier
* Note : Always Protect your Copier with a High Quality Surge
Protector.
The Basic Copy Process
Upon placing the original to be copied and then pressing the Print Button the following
sequences occur :
- Exposure Process : The Exposure Lamp (4) illuminates original image and refracts
this image through a series of mirrors thus enabling this image to reach the
photosensitive (light sensitive) Drum (5), and at the same time paper is drawn into to the
machine from the paper cassette by means of the Feed Tires (1).
- Image Formation Process : The Drum is electrically charged by the Primary Corona
Charger Assembly (3) in preparation to receive the refracted image of the original. With
the different graduations of light to dark areas of the refracted image striking the
electrically charged drum, this sets up a masking / de-sensitizing affect on the drum. The
sensitized areas left masked on the drum will accept and draw the the electrically
attracted toner from the DV Unit (6) to be placed on the Drum to produce an image.
- Registration Process : This enables the image on the drum to be properly
"registered" or aligned onto the paper. With the leading edge of the image
formed on the drum, and the leading edge of the paper traveling through the machine, they
will both meet in unison by means of the Registration Roller (2).
- Transfer Process : This is the process in which the image from the drum is
transferred onto the paper. The transference of the toner from the charged drum onto the
paper is carried out by the Transfer Corona Assembly (7). To put it simply the drum and
the toner on the drum have a (+) charge, and as the paper passes beneath the drum , the
Transfer Corona produces a (-) charge and with this transfer charge assembly placed
beneath the paper that is passing underneath the drum, this causes the toner to be drawn
off of the drum and onto the paper, thus the image is transferred onto the paper.
- Cleaning Process : This process cleans any residue / latent image that is left on
the drum and was not fully transferred to the paper. This residual image on the drum is
then wiped clean by the Cleaning Blade Unit (8) and captured as Waste Toner. The copied
paper is simultaneously carried via the Paper Transport (9) to the next and final process
(the fusing process).
- Fusing Process : This process permanently fuses / bonds the toner to the paper.
With the loose toner image on the copied paper reaching the Fuser Unit the image / toner
is then fused permanently to the paper by means of heat, roller pressure, and generally a
silicone oil.
Basic Copier Components and their function.
- Paper Feed Tire(s) : Paper Feed Tires are soft gummy rubber tire which picks up
the paper from the paper cassette and drives the paper to the Registration Rollers. Paper
Feed Tire(s) are a consumable part.
- Registration Roller : A soft rubber roller that synchronizes the leading edge of
the copy paper to the leading edge of the image placed upon the drum.
- Primary Charge Corona wire : A thin wire(s) housed in a lightweight metal slide
framework that electrical charges the Drum. The charge produced by this assembly changes
the sensitivity of the drum and allows the toner to be attracted to the drum for which
that image will then be transferred to the copy paper. The thin charge wire(s) and
accompanying insulating blocks are consumable parts.
- Exposure Lamp : A tungsten-hallogen lamp. This Lamp lights up to reflect the
image of your original to a series of lenses and optical mirrors and then onto the Drum.
The Exposure Lamp is a consumable part.
- Drum / Photoreceptor : A aluminum cylinder coated with a electrically and light
sensitive film coating. The Drum actually accepts the image. With the drum being
sensitive, appropriate areas of the drum are actually sensitized or de-sensitized
according to the amount of reflected light of the image received. Toner is then attracted
to the drum, from the electrical charge produced by the Primary Charge Corona wires and
from the intensity of light received. The toner image on the drum will then be next
transferred onto the paper. The Drum is a consumable part.
- Developer / Toner Unit (DV unit) : A modular unit which houses the developer and
toner. Most machines (except Canon) utilize both Developer and Toner. Toner is basically
micro fine ground up colored plastic with little or no magnetic / electrical properties.
Developer is either finely milled iron filings or magnetic ferrite. The developer acts as
a magnetic / electrical carrier which allows the toner to be carried from the magnetic
developer roller onto the electrically charged sensitive drum. As with Canon's patented NP
(New Process) machines, the developer and toner are combined as one to be known as NP
Toner. Developer and Toner are consumable supplies.
- Transfer / Separator Corona wire : A thin wire(s) housed in a lightweight metal
slide framework that electrical attracts the image / toner formed on the drum onto the
copy paper. At the same time this assembly aids in the separation of the electrically
charged paper away from the drum so the paper can continue to the next process. The thin
charge wire(s) and accompanying insulating blocks are consumable parts.
- Cleaning Unit : A modular unit which mechanically removes the latent image from
the previous copy made away from the drum. This unit not only generally contains a
magnetic roller (like that housed in the DV unit) but also a Cleaning Blade. The Cleaning
blade is nothing more than a silicone rubber strip attached to a metal bracket. This blade
comes in direct contact with the Drum and physically removes the latent image from the
previous copy made. The Cleaning Blade is a consumable part.
- Paper Transport : A carriage like assembly supporting several rubber drive belts
that transport the copied paper away from the Image Formation / Drum Area to the last and
final Fusing process. The rubber drive belts are a consumable part.
- Fuser Unit : The Fuser Unit actually fuses / permanently bonds the toner to the
paper. This is generally accomplished by running the paper through two rollers (the upper
roller being heated) that are under a pre loaded pressure and are often supplied with a
silicone fuser oil. The Upper Fuser Roller (UFR) is heated with a temperature controlled
tungsten-hallogen lamp (similar to the exposure Lamp). This UFR is a hard roller that is
coated a non-stick / easily cleanable silicone or Teflon coating. The Lower Fuser Roller
(LFR) are generally not heated and coated with a soft blanket of red silicone rubber. Many
machines utilize a Fuser Oil or silicone impregnated Cleaning Roller(s) to aid in the
fusing of the toner to the paper and avoid the copied paper sticking to the rollers. The
UFR, LFR, Roller Shaft Bearings, Heater Lamp, Cleaning Roller(s), and Fuser Oil are all
consumable parts.
Offering... Machines, and Both OEM and
Compatible Parts & Supplies for Most Major Makes & Models !
Canon * Copystar * Konica * Minolta * Mita *
Panasonic *
Ricoh * Savin * Sharp * Toshiba * Xerox
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