Printers

Getting it down on paper

Impact Printers

• Yes, they are still around and working!• Use a grid, or matrix, of printwires (pins) to push

the inked ribbon into the paper (the impact)• Used for multipart forms (two or more copies)• When noise and print quality not important• Measured in characters per second (300-500)• Use 9-pin (Draft quality) or 24-pin (Near letter

quality) printhead

Characters for Impact

• Bit-Mapped Font(s) – Put a dot here, put a dot there, … Whole chacacter described. Need one file for 10-point, another for 12.

• Mono-spaced fonts – each character gets the same width spacing

• Most of the “thinking” is done by the computer not the printer

Inkjet Printers

• Give the printer away, charge for ink

Ink well

Thermistor (Electroconductive Plates)

nozzle

This is NON-CONTACT printing

Inkjet (Print) Quality

• Print Resolution – Dots per inch, more is better

• Speed in pages per minute – with some undefined amount of characters – 8 to 15

• Cost of a set of cartridges can equal or exceed the printer’s cost

• Quiet printing and color on the desktop• Need paper that will absorb ink dot – or

not – for higher quality output

Math and Characters

• A Vector has a starting point, a length and a direction. The printer is handed a vector and prints it as best it can. Independent of printer resolution.

• Vector-based fonts (Postscript and TrueType); variable spacing for characters

Photo Printers

• Dye Sublimation – heat up solid ink to vapor, transfer to paper, cool back to solid

• Slip printers (at checkstands) a variation on this theme, but only black ink

• Each dot is continuous tone (color on color) rather than closely spaced color dots (dithering)

Laser Printers

• Classed as non-contact even though page is “ironed” at end of process

• Higher speed than inkjet, lower per-page cost, longer duty cycle (more pages per month)

• High voltage inside, and heat. Stay out!• If there is something wrong with the printer

that changing the toner cartridge won’t fix, call Terry Meyers.

Laser Printing

• Clean

• Charge

• Write

• Develop

• Transfer

• Fuse

• Clarence Carefully Wrote Down The Facts

Printing

• Clean– Physical by wiping off residual toner from

previous print cycle with rubber cleaning blade. Toner is recycled back to cartridge

– Erase lamp brings the charge to neutral on the drum

Printing, cont.

• Charge the drum– Primary corona wire writes a uniform negative

charge (600-1000v) to surface of drum– Does not contact drum surface

Printing, cont.

• Write the image– Laser is used to write a positive image (the

black goes here) to drum– Laser striking drum creates low voltage spot

on drum (~100v)

Printing, cont.

• Develop the image– Toner is attracted to low voltage areas of

drum (produced by laser)– Toner (ink, plastic and iron mix) is now on

drum

Printing, cont.

• Transfer the image– Uses transfer corona wire– Charges paper with positive charge – attracts

toner from drum to paper surface

Printing, done

• Fusing– Pressure roller (on bottom) and heated roller

(on top) melt toner into paper– Static eliminator brings page back to neutral

charge

Electronics of Printing

• Vector (TrueType) is converted to raster (series of dots) to commands for the laser

• Raster Image Processor (RIP) used here. Usually this is your CPU’s task

• Can get memory intensive so lasers can run out of memory for the page (QuarkExpress is known for this)

Printer Port

• Maximum data rate is 150KBps with a lot of CPU cycles for standard port

• IEEE 1284 standard defined parallel port modes, physical and electrical interfaces

• Enhanced Parallel Port (EPP) – constant two-way communication with PC

• Extended Capacity Port (ECP) – even faster communication

USB Printers

• Most printers sold today can connect via USB

• Need to install the drivers first, as with any USB device

• Allows connection to Mac or PC

Network Printers

• Share from one PC. PC has to be on, share it in the Printers Window

• Print Server box. Box connects to network (Ethernet); printer connects to box (USB or parallel).

• Standalone. Printer is its own device on network – wired or wireless

Fonts

• Fonts, or Faces, are different ways to represent a character

• Bangle Font – AIC is done this way• Bodoni Font• Century Gothic Font• Eurasia Font• French Script MT Font• Flatbrush Font

Printer Languages

• ASCII – American Standard Code for Information Interchange. This is the core of printing. Additional information is in ASCII codes via “control codes” or “escape sequence”

• Dot matrix printers have one, or more, built-in fonts; inkjet and lasers do not.

Printer Languages

• Postscript. Developed by Adobe Systems. High resolution graphics and text – at a withering high license fee of $1000/printer

• TrueType. Character “map” method that mostly gets around PostScript.

• Printer Control Language (PCL). HP’s route around PostScript. Just characters

Setting Up a Printer

• Plug in parallel cable (system off) then load drivers when Windows asks for them

• Choose Add New Printer from Printers window for networked printer

• Install drivers first, then plug in USB printer

Printers and Devices

• The Printer is a program that controls one (or more) print devices

• The Printer includes the print driver and print spooler

• So… you install the printer and connect the print device(s)

Troubleshooting

• Clean – if not, you will get random spots on pages• Charge – if not, you will get random white areas on the

page• Write – if not, little or nothing written to page• Develop – again, blank (white) spots on page at

repeated intervals down page• Transfer – banded section of white where text should be• Fuse – toner will fall off the paper. This is only issue that

replacing the toner cartridge will not fix.• A scratch on the drum will produce vertical lines on the

page

And More

• Check the Print spooler if print jobs do not come out. A ‘sticking’ print job will hold up following print jobs.

Multiple Printers

• On one port need a switchbox (single in, selectable out). Don’t use mechanical switchbox with laser printers

• On multiple ports, use the Print dialog box to select printer

• Selected printer does not have to be default printer

Dot Matrix Printers

• Vacuum out, or blow out, paper “dander”

• Keep platten clean – use alcohol

• Avoid the urge to clean printhead – you will make a mess of it and shorten its life

• Replacing a printhead that has failed is about 2/3 the cost of new printer

Laser Printers

• Again, if replacing the toner cartridge does not solve the problem, call Terry Meyers

• CompTIA wants you to vacuum the printer each time you change toner

Inkjet printers

• Best maintenance is to use the printer

• Clean printhead to remove streaks, but it uses ink

• Finding the maintenance options window can be a real challenge