Identify specification of types of fuses. Identification and specification of type of switches
ICTSM AND CHNM TRADES Trade IN ITI has a wide scope of Employ-ability ranging from self-employment, contractual employment to Industrial jobs. On successful completion of this course, the candidates shall be gainfully employed in the industries for following occupations: ICT Engineer.
Identify specification of types of fuses. Identification and specification of type of switches
Safety in moving and shifting heavy and delicate equipment's.
https://www.youtube.com/watch?v=LqmZzTh7Kp8 |
There Are Following Steps for Laser Printing Process
NOTE *easy way to remember this is CLEAN CARS WILL DRIVE TO FAST
Cleaning
Before a new page is printed; any remnants from the previous page are cleared
away. The drum is swept free of any lingering toner with a rubber blade, and a
fluorescent lamp removes any electrical charge remaining on the drum. Any toner
removed in this step is not re‐used but is put into a used‐toner compartment on
the cartridge.
Conditioning The
entire drum is uniformly charged by the primary corona wire. This charge
conditions the drum for the next step.
Writing The
laser printer controller uses a laser beam and a series of mirrors to create
the image of the page on the drum. The laser beam is turned on and off in
accordance with the image to be created on the drum. At the spot where the
laser's light contacts the photosensitive drum, the charge is reduced. After
the entire image has been transferred to the drum, the controller starts the
page sheet through the printer, stopping it at the registration rollers.
Developing A
magnet inside the developing roller attracts the iron particles in the toner.
This roller rotates near the drum and the toner is attracted to the areas of
the drum that have been exposed by the laser, creating the print image on the
drum.
Transferring
The back of the paper sheet is given a positive charge that attracts the
negatively charged toner from the drum onto the paper as it passes. After this
step, the paper has the image of the page on it, but the toner, which is held
only by simple magnetism, is not yet bonded to it.
Fusing The
fusing rollers apply heat and pressure to the toner, which melts and presses it
into the paper to create a permanent bond. The rollers are covered with Teflon
and treated with a light silicon oil to keep the paper from sticking to them.
Your printer will have come with a user manual that should explain the
necessary cleaning and maintenance that should be undertaken. On the
manufacturers' websites you will find a support section where you can download
support details on their products.
The following are the main parts of a laser printer:
Drum The drum inside
the toner cartridge is photosensitive, which means it reacts to light. The drum
holds an electrostatic charge (except where it is exposed to light). The laser
beam is reflected onto the surface of the drum to create a pattern of charged
and not-so-charged spots, representing the image of the page to be printed.
High‐voltage power
supply The process uses very high voltage to charge the drum and transfer and
hold the toner on the paper. The high-voltage power supply converts AC current
into the higher voltages used by the printer.
DC power supply Like a
computer, most of the electronic components in the laser printer use direct
current. For example, logic circuits use +5V DC (volts direct current), and the
paper transport motors use +24V DC.
Paper transport Inside
the laser printer are four types of rollers that move the paper through the
printer. Each rubberized roller or set of rollers is driven by its own motor.
The four roller types in the paper transport system are the feed, registration,
fuser and exit roller. This is where most paper jams in a laser printer occur.
Primary Corona Also
called the main corona, this device forms an electrical field that uniformly
charges the photosensitive drum to +600V to reset it prior to receiving the
print image and toner.
Transfer Corona This
mechanism moves a page image from the drum to the paper. The transfer corona
charges the paper; the charge pulls the toner from the drum onto the paper. As
the paper exits the transfer corona, a static charge eliminator strip reduces
the charge on the paper so that it won't stick to the drum. Not all printers
use a transfer corona; some use a transfer roller instead. When working on a
printer with a transfer roller, be careful not to touch the roller. The oils
from your skin can spot the transfer roller and cause improperly charged paper,
resulting in defects in the printed image.
Fusing Rollers The
toner is melted permanently to the page by the fusing rollers that apply
pressure and heat (between 165 and 180C) to it. The fuser - not the laser -
makes the printed pages hot.
Controller This is the
motherboard of the laser printer, and it has architecture and components like a
PC motherboard. The controller communicates with the PC, houses the memory in
the printer, and forms the image printed on the page. Memory expansion is
possible on virtually all laser printers. Adding memory allows the printer to
reproduce larger documents or graphics in higher resolutions or to support
additional soft fonts.
A printer that
experiences frequent memory overflow errors may require more memory or has a
bad memory board. Check what was being printed when the fault occurs, as memory
overflow is more likely to be the cause.
Poor Print Quality
Paper Jams
Connection Issues
Inaccurate Scaling or Alignment
Unusual Noises
Slow Printing Speed
Firmware Errors
Line Printer
The
line printer is an impact printer in which one line of text is printed at a
time. They are mostly associated with unit record equipment and the early days
of digital computing, but the technology is still in use.
A
line printer is a high‐speed printer capable of printing an entire line of text
at once instead of one or more characters at a time. These types of printers
are too fast to be measured in words or characters per minute, and instead are
measured in lines per minute. For example, a line printer may be capable of
printing over 3,000 lines of type per minute.
A
high‐speed printer capable of printing an entire line at one time. A fast line
printer can print as many as 3,000 lines per minute. The disadvantages of line
printers are that they cannot print graphics, the print quality is low, and
they are very noisy.
Line
Printers: ‐ Line Printer can Print One Line at a Time. The line printer is a
form of high speed impact printer. They can Print 300 to 3000 Lines per Minute.
So that they are very fast. Large Computer system typically uses Line Printer.
The Line Printers are of two Types.
Drum
Printers: ‐ Drum Printer consists of a Drum Which Consists of a Number of
Characters; those are Printed on the Drum. And the Number of Characters or
Number of Tracks are Divided, after examining the width of the Paper. But there
are also Some Character sets Available Means the Number of Characters those are
printed on the Paper. For Example 64, and 96 Characters etc.
In
this Paper is placed between the Ribbon and the Head or Hammer there are many
hammers on the Front of Drum. In this Drum Rotates at a Very High Speed and
character is printed by activating the Appropriate Hammer. So always remember
that All the Characters are never printed at a Time, but they are printed at a
very high Speed. And they can print only a Pre Defined Styles because the Drum
has a Specific Characters. Those are placed on the Drum. So that they cant
print the various Types of Fonts and Color Pictures. And Drum Printers are also
noisy because they use Hammering Techniques.
Chain
Printers: These are also Line Printers, which Prints one Line at a Time. All
the Characters are printed on the Chain and the Set of Characters are placed on
the Chain. There are 48 and 64 and 96 Characters set Printers are Available.
There are also Some Hammers, those are Placed in Front of the Chain, and Paper
is Placed between the Hammer and the Inked Ribbon. The Total Number of Hammers
will be Equals to the Total Number of Print Positions.
In
this Chain Rotates at a Very High Speed and Character is printed by activating
the Appropriate Hammer of the Character. Chain Printers can also print some Pre
Defined characters and we can’t Display the High Quality of Fonts and Font
Styles. They are also Impact Printers and Also Noisy because they Prints the
Characters by Hammering Action. And these Printers can print the 400 to 3000
Lines Per Minute.
A printer is any device that prints text or illustrations on paper. There are many different types of printers. In terms of the technology utilized, printers fall into the following categories:
1. daisy‐wheel: Similar to a ball‐head typewriter, this type of printer has a plastic or metal wheel on which the shape of each character stands out in relief. A hammer presses the wheel against a ribbon, which in turn makes an ink stain in the shape of the character on the paper.Daisy‐wheel printers produce letter‐quality print but cannot print graphics.
2.
dot‐matrix: Creates characters by striking pins against an ink ribbon. Each pin
makes a dot, and combinations of dots form characters and illustrations.
3.
ink‐jet: Sprays ink at a sheet of paper. Ink‐jet printers produce high‐quality
text and graphics.
4.
laser: Uses the same technology as copy machines. Laser printers produce very
high quality text and graphics.
5.
LCD & LED :Similar to a laser printer, but uses liquid crystals or
light‐emitting diodes rather than a laser to produce an image on the drum.
6.
line printer: Contains a chain of characters or pins that print an entire line
at one time. Line printers are very fast, but produce low‐quality print.
7.
thermal printer: An inexpensive printer that works by pushing heated pins
against heat‐sensitive paper. Thermal printers are widely used in calculators
and fax machines.
What
is a Printer? A printer is an electromechanical device which converts the text
and graphical documents from electronic form to the physical form. Generally
they are the external peripheral devices which are connected with the computers
or laptops through a cable or wirelessly to receive input data and print them
on the papers. A wide range of printers are available with a variety of
features ranging from printing black and white text documents to high quality
colored graphic images.
Quality
of printers is identified by its features like color quality, speed of
printing, resolution etc. Modern printers come with multipurpose functions i.e.
they are combination of printer, scanner, photocopier, fax, etc. To serve
different needs there are variety of printers available that works on different
types of technologies.
Types
of Printers Since the invention of the printing technology, a variety of
technologies have been employed in computer printers. Broadly printers are
categorized as impact and non impact printers. Impact printers are the type of
printers in which a key strikes the paper to make a letter. The examples of Impact
printers are Daisy wheel and Dot matrix printers. While non‐impact printers do
not operate by striking a head against a ribbon. Inkjet printers and laser
printers are the non‐impact printers. The most popular printers are described.
1. Daisy
Wheel Printers Daisy wheel printers print only characters and symbols and
cannot print graphics. They are generally slow with a printing speed of about
10 to 75 characters per second. By 1980 daisy wheel printers were the dominant
printers for quality printing but since the prices of laser and inkjet printers
have declined and quality of dot matrix printers has been improved, the daisy
wheel printers are now obsolete.
Working
of daisy wheel printers is very similar to typewriters. A circular printing
element (known as daisy wheel, shown in the below image) is the heart of these
printers that contains all text, numeric characters and symbols mould on each
petal on the circumference of the circle. The printing element rotates rapidly
with the help of a servo motor and pauses to allow the printing hammer to
strike the character against the paper.
2. Dot Matrix Printers It is a popular
computer printer that prints text and graphics on the paper by using tiny dots
to form the desired shapes. It uses an array of metal pins known as print head
to strike an inked printer ribbon and produce dots on the paper. These
combinations of dots form the desired shape on the paper. Generally they print
with a speed of 50 to 500 characters per second as per the quality of the printing
is desired. The quality of print is determined by the number of pins used
(varying from 9 to 24).
3. Inkjet
printers Inkjet printers are most popular printers for home and small scale
offices as they have a reasonable cost and a good quality of printing as well.
A typical inkjet printer can print with a resolution of more than 300 dpi and
some good quality inkjet printers are able to produce full colored hard copies
at 600 dpi. An inkjet printer is made of the following parts:
∙
Print
head – It is the heart of the printer which holds a series a nozzles which
sprays the ink drops over the paper.
∙
Ink
cartridge – It is the part that contains the ink for printing. Generally
monochrome (black & white) printers contain a black colored ink cartridges
and a color printer contains two cartridges – one with black ink and other with
primary colors (cyan, magenta and yellow).
Stepper
motor – It is housed in the printer to move the printer head and ink cartridges
back and forth across the paper. .
Stabilizer
bar – A stabilizer bar is used in printer to ensure the movement of print head
is précised and controlled over the paper. .
Belt
– A belt is used to attach the print head with the stepper motor.
.
Paper
Tray – It is the place where papers are placed to be printed.
.
Rollers
– Printers have a set of rollers that helps to pull paper from the tray for
printing purpose. . Paper tray stepper
motor‐ another stepper motor is used to rotate the rollers in order to
pull the paper in the printer. .
Control
Circuitry – The control circuit takes the input from the computer and by
decoding the input controls all mechanical operation of the printer.
Similar
to other printers, inkjet printers have a ‘print head’ as a key element. The
print head has many tiny nozzles also called as jets. When the printer receives
the command to print something, the print head starts spraying ink 33 over the
paper to form the characters and images. There are mainly two technologies that
are used to spray the ink by nozzles. These are:
∙
Thermal
Bubble – This technology is also known as bubble jet is used by various
manufacturers like Canon and Hewlett Packard. When printer receives commands to
print something, the current flows through a set of tiny resistors and they
produce heat. This heat in turn vaporizes the ink to create a bubble. As the
bubble expands, some of the ink moves out of the nozzle and gets deposited over
the paper. Then the bubble collapses and due to the vacuum it pulls more ink from
ink cartridge. There are generally 300 to 600 nozzles in a thermal printer head
which can spray the ink simultaneously.
∙
Piezoelectric
– In the piezoelectric technology, a piezo crystal is situated at the end of
the ink reservoir of a nozzle. When printer receives the command to print, an
electric charge is applied to the crystal which in turn starts vibrating and a
small amount of ink is pushed out of the nozzle. When the vibration stops the
nozzle pulls some more ink from the cartridge to replace the ink sprayed out.
This technology is patented by Seiko Epson Corporation.
An
inkjet printer can print 100 to several hundred papers depending on the nature
of the hard copy before the ink cartridge need to be replaced.
4. Laser
Printers Laser printers are the most popular printers that are mainly used for
large scale qualitative printing. They are among the most popularly used
fastest printers available in the market. A laser printer uses a slight
different approach for printing. It does not use ink like inkjet printers,
instead it uses a very fine powder known as ‘Toner’. Components of a laser
printer are shown in the following image:
The
control circuitry is the part of the printer that talks with the computer and
receives the printing data. A Raster Image Processor (RIP) converts the text
and images in to a virtual matrix of dots. The photo conducting drum which is
the key component of the laser printer has a special coating which receives the
positive and negative charge from a charging roller. A rapidly switching laser
beam scans the charged drum line by line. When the beam flashes on, it reverses
the charge of tiny spots on the drum, respecting to the dots that are to be
printed black. As soon the laser scans a line, a stepper motor moves the drum
in order to scan the next line by the laser.
An MFP (Multi Function Product/ Printer/ Peripheral), multifunctional, all‐in‐one (AIO), or Multifunction Device (MFD), is an office machine which incorporates the functionality of multiple devices in one, so as to have a smaller footprint in a home or small business setting (the SOHO market segment), or to provide ...
MFD
(Multi Function Device) integrates all these four functions into a single
device. Therefore you only buy a single machine and save money and space. There
are many MFD brands such as HP, Epson, Canon, Lexmark, Samsung and Brother are
available. The price of most of these MFDs are affordable.
MFDs
are also called 'All‐in‐One' device. Printing, Scanning, Photocopying and Faxing
all in one device. Most people now do not use FAX and therefore
there
are many MFD models without FAX
A
product or device that has multiple functions. An example of this might be a
printer that also makes copies, faxes, and scans. Another example is a CD or
DVD that might contain multiple applications on the same disk; this may be a
Mac and PC version of the same software or media meant to be played on more
than one platform. Also called multi function product (MFP), all‐in‐one.
A
product or device that has multiple functions. An example of this might be a
printer that also makes copies, faxes, and scans. Another example is a CD or
DVD that might contain multiple applications on the same disk; this may be a
Mac and PC version of the same software or media meant to be played on more
than one platform. Also called multi function product (MFP), all‐in‐one
A
multifunction peripheral (MFP) is a device that performs a variety of functions
that would otherwise be carried out by separate peripheral devices. As a rule,
a multifunction peripheral includes at least two of the following:
Multifunction peripheral devices often have a base function with one or more added capabilities. Here are some common examples:
A
Multifunctional Device, or MFD, is typically the printing device in most
offices but is referred to as a printer or photocopier. These machines
incorporate scanning, copying and printing as a minimum, into a single device –
some can also be used for emailing and faxing.
AIM :- How to clean printer head?
Equipment:-
A
blocked printer head greatly affects the performance of the printer. It may be
caused by dried ink because it has not been used for a long period of time.
This causes poor printing job leading to waste of ink and paper and may
eventually damage the printer. It is extremely important to clean out the
printer head when it is clogged.
Procedure :-
How To Clean Print Heads - Instructions for Printer Head Cleaning
If a printer has not been used for a long period of time, the
many tiny holes that make up a modern inkjet printer's head may become clogged
with dried ink. Clogged printer heads greatly affect the quality of the
printing job and can eventually lead to damage to the printer. It is very
important to clean out printer heads when they are clogged.
Printer Self-Cleaning
Most inkjet printers have some sort of automatic utility program
by which you can instruct the printer to go through a self-cleaning cycle. A
number of these cleanings, in succession, will usually take care of a clogged
printer head. However because the cleaning cycle needs to be repeated multiple
times, a significant amount of ink can be consumed during this process - as
much as 10-25% of the cartridge's ink.
If the self-cleaning cycle does not solve the problem, try
turning the printer off overnight to allow the ink to soften. Turn the printer
on the next day and try printing a test pattern to see whether the problem has
either disappeared or become less noticeable. This ink-saving procedure can
work effectively because sometimes the dried ink on the print head needs time
to soften before the printer head can be cleaned completely. Try running the
self-cleaning utility again one or more times.
Steps for Manually Cleaning the Printer Head
If the overnight cleaning still does not work, there may be a
layer of thick ink that is blocking the holes of the printer's head. The next
option is to manually clean the printer head. Follow these steps:
·
Determine from the
owner's manual where the print head is located.
· Remove the ink
cartridge from your printer and then dip a cotton swab in hot water or
isopropyl alcohol and rub it against the print head. This should loosen any
crusted ink. NOTE: Be careful, especially if you use isopropyl alcohol to clean
your print heads: Some printers use rubber gaskets, and if you get isopropyl
alcohol on the gaskets it could dry them out.
· For models where the
print head is in the printer, drop 7 to 10 drops of isopropyl alcohol (91%
denatured isopropyl alcohol - not 'rubbing' alcohol) down the ink receptacle
area where the ink actually flows from the cartridge into the head. Run a few
self-cleaning utilities. If possible, allow the printer to sit a few hours or
overnight and repeat the self-cleaning utility.
· If the print head is
in the cartridge, soak the cartridge print head in hot water. Allow it to soak
overnight. Dry the print head area with a paper towel. Repeat the self-cleaning
utility.
· If the hot water soak
did not unclog the print head, place the cartridge printer head in isopropyl
alcohol and allow it to soak overnight. Use a damp paper towel to wipe off the
print head area and dry carefully. Try the self-cleaning utility again.
· If the alcohol soak
did not unclog the print head in the cartridge you may need to purchase a new
cartridge. This will provide new print heads that won't be clogged. Contact a
service technician for repair of print heads in the printer if the alcohol did
not unclog the printer head.
Preventive Maintenance
It's a good idea to regularly conduct preventive maintenance on
your inkjet printer to prevent it from developing clogged printer heads. Some
steps you can take include:
· Since print heads
become clogged when not used for long periods of time, regularly print a page
or two to keep the print heads clear. Some experts say that it is better to
print one colorful page a week than to run a printer cleaning cycle, because
doing so uses a lot less ink.
· Turning the printer
off when it is not in use can save the printer head from getting clogged with
dried ink. Leaving the printer on keeps the ink in the cartridge warm and can
make it bleed onto the printer head.
· If you need to store
your printer it would be best to take the printer cartridge out. Be careful to
never touch the printer head with oily or dirty hands - this can leave skin oil
on the printer head and add to the possibility of it getting clogged.
·
Ideally, printer
cleaning cycles should be started once a week to prevent the printer head from
getting clogged.
There are other more ink-efficient ways to be able to clean
printer heads that will prevent their clogging just as effectively as running
the printer's cleaning cycle:
Aim :- HOW
TO REFILL TONER CARTRIDGE
Equipment:
- Printer Cartridge
Row
Material: - Toner Powder For Printer
Theory:
- A toner cartridge, also called laser toner, is the consumable component of a
laser printer. Toner cartridges contain toner powder, a fine, dry mixture of
plastic particles, carbon, and black or other coloring agents that make the
actual image on the paper.
Procedure :-
Step
1: Unscrew the both end of the hp 12 toner cartridge. Total you will find 4
screws.
Step
2: Open the drum side cover by just pulling it from drum gear side.
Step
3: Get out the drum by simply sliding the drum by side.
Step
4: Remove the magnetic roller by slightly making gaps and inserting the twiser
on the other side of the hp 12 a toner.
Step
5: Remove the magnetic roller washer by the twiser.
Step
6: Open the other end of the cartridge by pulling it gently until it separated.
Step
7 : Separate the other end of the hp 12 a toner cartridge. Do not remove the gears
Step 8 : You have successfully separated the cartridge.
Then you will get two part, one is waste toner part and other is empty toner
part.
Step
9: Get out the tension spring located at waste toner part.
Step
10: Remove the drum pressure roller from the waste toner part of the hp 12 a
cartridge
Step
11: You will see the wiper blade just below the pressure roller. Unscrew and
remove the wiper blade and clean it by soft cloth. Do not twist the transparent
blade part.
Step
12: You will see waste toner dust beneath the wiper blade. Remove the waste
dust completely with the help of brush. And clean it gently by a soft cloth. Do
not damage the plastic film blade that is stick on the
cartridge.
Step
13: Fix the wiper blade and fasten the screw gently.
Step
14: Clean the drum pressure roller by soft cloth and check for any dry sticky
dust on the roller. If necessary, clean the roller by a wet cloth.
Step
15: Fix the pressure roller to its position.
Step
16: Make empty the tonner unit is any dust remains.
Step
17: Shake well the tonner dust before refilling. Pour the dust by help of a
piece of paper.
Step
18: Assemble the both unit of the cartridge gently. Check for correct
adjustment i.e, no gaps remains on the either sides of the hp 12 a toner
cartridge. Do not make excess pressure during assembling, simply make the
position it will get its position softly.
Step
19: Clean the magnetic roller with a soft cloth. Do not rub hard thoroughly.
Step
20:Fix the gear and washer of the magnetic roller.
Step
21: Fix the magnetic roller gently. Locate the spring part of the magnetic
roller 'D' shaped. Match the shape with the cartridge body.
Step
22: During fixing of the magnetic roller you have to make slight gap so,that
the gear gets its right position.
Step
23: If necessary use a new drum for the best result. Place the drum by gently
sliding to the cartridge body. Do not touch the drum area, hold the drum by its
gear.
Step
24: Fasten all the screws.
Step
25: Place the tension spring by the help of a twiser.
Step 26: Just get test print....Enjoy.