PRINTERS AND PRINTING

A+ likes you to know the mechanics, the processes and the problems with printing.

Historically parallel port devices were chosen for PC printing because device installation and operation was fast and trouble free.

Because of conflicting manufacturer standards, a serial port device can oftentimes be a pain in the ASCII to set up – in both cabling and setup.

Below is a chart illustrating the basic differences between parallel, serial. Very A+

Note that newer busses exist now (USB and IEEE1394) that are replacing these interfaces.

Typical connection - Very A+

• Parallel, Centronics, (LPTx)

  Female 36 pin Centronics on printer.                      25-Pin D-Shell on computer.

• Serial, RS-232, (COMx)

  9 or 25 Pin male D-Shell on computer.                        25-pin female on printer.
  

• Network card or device

IMPACT PRINTERS

Daisy Wheel - Fully formed characters

• Multi-part forms

Mechanics

• 9 - 18 - 24 pins - Very A+
• Print head & ribbon
• Platen
• Tractor (NCR) & friction feed (paper feed selector)
• Driver

Process

• Pins strike ribbon – ribbon strikes paper
• Forms characters dot-by-dot

Problems

• Online button - Very A+
• Hot print head - don't oil, may clean with denatured alcohol - Very A+
• Faded text - head-gap lever
• Smudged ink - paper too thick
• White bars - dirty/damaged print head
• Light to dark (left to right) - platen damaged - Very A+
• Paper dander! Use compressed air

RIBBON	TIMING BELT	RIBBON MASK	GLIDE RAIL	PLATEN
TENSION KNOB	PRINT HEAD	RIBBON CARTRIDGE	SIGNAL CABLE FROM CONTROLLER BOARD
The (dot) Matrix

NON-IMPACT

Inkjet

Mechanics

• Ink cartridges
• Platen
• Gear train
• Paper feed roller(s)
• Friction feed
• Timing belt - moves head
• May be a multi device (scanner/fax/copier)

Processes - Very A+

1. Drop on demand
   • Thermal shock - heats the ink, bubbles out. 400º>
   • Mechanical vibration - ink vibrates out – Epson

     Drop on demand
     

     • Ink is placed onto paper drop by drop
     • Ink from one or more cartridges
     • Forms characters drop-by-drop

2. Continuous stream
   • High output commercial use
   • Ink is given a negative charge in an ion chamber and then passed through a set of high voltage deflection plates that "bend" the ink to correct position on the page. Historically Very A+
   • Stream of ink is sprayed out though a nozzle
   • Directed magnetically much like the process of bending an electron beam inside a CRT.

     
     

     Continuous Stream
     

     • IBM 4640 (1976)
     • A.B. Dick VideoJet
     • Iris Inkjet

• Maintenance mode
• Clogged jets – more paper dander!
• May require calibration
• Consumables

LASER PRINTERS
Laser printers rely on the photoconductive properties of certain compounds - when exposed to light these compounds conduct electricity. For accuracy, laser printers use lasers as a light source.

Mechanics - Very A+

Main components

• Photosensitive aluminum drum
• Erase lamp
• Primary corona
• Laser
• Toner - small plastic particles
• Transfer corona
• Fuser (~400 degrees - thermal sensor to protect printer)
• Ozone filter
• Consumable components - There's HP & everybody else

HP – all in one	Others – separate components

Gang of Six - know them all! - Very A+

1. Cleaning
2. Conditioning
3. Writing
4. Developing (transferring toner)
5. Transferring image
6. Fusing

Processes

1. Cleaning - drum cleaned using erase pad and erase lamp. Drum is physically clean with a neutral charge.

   Problems arise when these components wear or become defective. Vertical streaks, smearing, ghosting or double imaging, background haze and a peppering of loose toner are indications of problems during this process.

2. Conditioning - primary corona wire applies a negative charge to drum. Ionizes air with high voltage (between -600 & -1000 volts)

   An uncharged drum may produce a black page. A poorly charged drum can streak. A conditioning streak is different from a wiper blade streak because the wiper blade streak is constant while a corona streak is inconsistent and varies in width.

3. Writing - laser image is reflected onto drum. Areas "hit" are lightly discharged (through ground) leaving a pattern of the image on drum (-100 volts).

   If the laser does not make complete contact with the drum, voided or missing print is a common resulting defect. Conversely, if the laser is always on, the entire page is black.

4. Developing (Transferring Toner) - This attracts the more negatively charged toner (-200 to -500 volts). Note that the image area is at –100 volts and is considered to be "relatively" positive to the toner.

   If any one of the components are faulty, the result is a light print, leaking or spilling, excess waste toner, and toner build up on the fuser assembly.

5. Transferring - the paper is then positively charged by the transfer corona wire.

   Negative charged toner leaps over to the paper from the drum. The paper's charge is then removed with a static eliminator comb so it won't stick to drum.

   A poor charge will result in light print, poor transfer of toner and perhaps even a blank page creating more waste toner.

6. Fusing - two heated rollers melt toner to the paper.

   A poor fusing assembly will give you raised print, toner flaking, light print, ghosting and sometimes excess build-up on the cleaning pad.

   
   

   Problems - Very A+

   • Vertical white lines - shake toner
   • Faint image - replace toner
   • Blank page - bad transfer corona wire
   • Black page –
     • laser always on
     • faulty primary corona
   
   

    

   THERMAL - can run from the very low-end to the very high-end

   • Heat sensitive paper (low-end)
     • Cash register receipts
   • Solid ink (high-end) - A+
     • Simple paper path
     • Fast and colorful
     • Ink stick melted and then sprayed onto drum
     • High quality color – cheap
     • Extremely high volume
     • Flexible medium – poor on transparencies
     • 40,000 pages without a refill
   • Dye sublimation (high-end) - A+
     • Vaporizes sheets of colored film
     • High-end – excellent color gradations
     • Expensive to buy and maintain
     • Special paper

Printers and the OS

Start / Settings / Printers

• Add printer
• Alternate Click - Set as default (black checkmark)
• Alternate Click - Properties

 

Print Spooler

• Double-click printer to manage spool
• Menu items
  • Pause and Cancel
  • Set as default
  • Properties
• Spool32 errors
  • \windows\system\spool32.exe - replace
  • \windows\spool\printers - clear
  • Out of disk space - free disk space and/or enlarge VM
  • Set spool data format to RAW
  • Clean boot - selective startup in MSCONFIG