Printers & MFDs Flashcards
Impact Printers (General)
Printers that create an image on paper by physically striking an ink ribbon against the paper’s surface.
Daisy-Wheel Printers
An electric typewriter attached to the computer instead of directly to a keyboard (have largely disappeared)
Dot-Matrix Printers
Printing process in which ink is applied to a surface using a relatively low-resolution dot matrix for layout
Able to print arbitrary patterns (not just specific characters)
Use a grid/matrix of tiny pins (aka: printwires) to strike an inked printer ribbon and produce images on paper.
Printhead: Case that holds the printwires
BIOS in printer interprets the raster image the same way a monitor does
Reasons for Dot-Matrix Use
Dot-matrix printers have a large installed base in business, and can be used for multipart forms because they actually strike paper.
Can print receipts/docs in duplicate, triplicate, or more.
POS machines represent major market for impact printers
Tractor-Feed Paper (Impact)
Dot matrix uses continuous-feed paper with holes on its sides that are engaged by metal sprockets to pull the paper through.
Duplex Assemblies
Enable the printer to automatically print on both sides of the paper.
Inkjet Printers (Ink-Dispersion Printers)
Uses a printhead connected to a carriage that contains the ink.
A belt & motor move the carriage back and forth so the ink can cover the whole page.
Roller grabs paper from a paper tray/feeder and advances it through the printer.
Ink is ejected through tiny tubes (most use heat to move ink, some mechanical)
Inkjet (Heat Method)
Uses tiny resistors or electroconductive plates at the end of each tube that literally boil the ink.
Creates a tiny air bubble that ejects a droplet of ink onto the paper.
Print Resolution
How densely the printer lays down ink on the page.
Measured in DPI (dots per inch)
Higher DPI = Higher quality
Print Speed
Measured in PPM (pages per minute)
Inkjet Maintenance:
Calibrate, Clean Heads, Replace Cartridges, Calibrate, Clear Jams
When first setting up, printer will instruct you to perform a routine (calibration) to align printheads properly. Printer will print a test page.
Cartridges simply slide into place, but printer may have clips to lock them in.
Ink inside printhead nozzles can dry out, blocking the ink. Inkjets have head-cleaning maintenance programs (either on printer itself or in Windows)
Humidity can cause paper to cling together. Sometimes overheated printer can do so as well.
Give the printer a break and fan the sheets of paper before inserting into the tray.
Impact Maintenance:
Replace Ribbon, Replace Print Head, Replace Paper
Keep the platen and the printhead clean with denatured alcohol.
Lubricate the gears & pulleys according to manufacturer specifications.
Replace ribbon every so often.
Finish feeding the rest of the current paper roll. Swap out old roll with new paper roll and feed the new roll according to manufacturer specifications.
Thermal Maintenance:
Replace Paper, Clean Heating Element, Remove Debris
Heating Element: Turn off printer & open it according to manufacturer instructions. Use denatured alcohol and a lint-free cloth to wipe off the heating element.
Clean rollers with cloth/compressed air to remove debris so they can properly grip paper.
Swap paper roll out with new one and feed through the heating element.
Laser Maintenance:
Replace Toner, Apply Maintenance Kit, Calibrate, Clean
Clean printer every time you replace the toner cartridge.
Use compressed air to remove paper dander and excess toner from the printer (preferably outdoors). If indoors, use a toner vac (low static vacuum).
Clean guide rollers with denatured alcohol & fibrous cleaning towel.
Many manufacturers provide maintenance kits that come with replacement parts (fuser, rollers, pads). Reset page counter after installation.
Some ozone filters can be vacuumed, some require replacement. Fuser assembly, transfer corona & paper guides can be cleaned with denatured alcohol.
Check heat rollers for damage, if scratched, replace the fuser unit. (Most will give error code)
Check printer manual for registration & color calibration methods. Some will do this automatically.
Apple: Bonjour Print Service & AirPrint
Bonjour provides a general method to discover services on a LAN. It locates devices such as printers & other computers, and the services those devices offer.
AirPrint is a feature of macOS that allows printing via WLAN either directly to AirPrint compatible computers, or non-compatible shared printers on Windows/Linux.
Thermal Printers (General)
Use a heated printhead to create a high-quality image on special/plain paper.
Direct Thermal
Use a heating element to burn dots into the surface of special heat-sensitive thermal paper.
Many retail stores use this for receipt paper.
Use large rolls of thermal paper housed in a feed assembly that automatically draws paper past the heating element.
Thermal Wax Transfer
Uses film coated with colored wax (ribbon roll)
Thermal printhead passes over the ribbon & melts the wax onto paper
Don’t require special papers like dye-sublimation (more flexible/cheaper)
Laser Printers (General)
Laser printers use electro-photographic imaging to produce high-quality & high-speed output of both text & graphics.
They rely on photoconductive properties of certain organic compounds. Most use lasers as the light source (some lower-end use LED arrays).
Photoconductive (Definition)
Particles of compounds that, when exposed to light, will conduct electricity.
Laser Printers: Imaging Drum
An aluminum cylinder coated with particles of photosensitive compounds.
The drum itself is grounded to the PSU (coating isn’t).
When light hits the particles, whatever electrical charge they have “drains” out through the grounded cylinder.
Laser Printers: Erase Lamp
The erase lamp exposes the entire surface of the imaging drum to light, making the photosensitive coating conductive.
Any electrical charge present in the particles bleeds away into the grounded drum, leaving surface particles electrically neutral.
Laser Printers: Primary Corona/Charge Roller
When charged with an extremely high voltage, an electric field (corona) forms, enabling voltage to pass to the drum & charge the photosensitive particles on its surface.
Primary grid regulates the transfer of voltage, ensuring the surface of the drum receives a uniform negative voltage between 600-1000V.