Printing Technology and Printers: Dot Matrix, Ink-jet, Laser, and High-Quality Printers, Lecture notes of Computer Networks

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• EE121
• LEC

Printing Popular printing technology builds up characters on page, as on the screen, as a series of dots. Allows any character set or graphic to be printed, depending on the resolution of the dots, measured in dots per inch (dpi).

• dot-matrix printers use inked ribbon, with a line of pins that can strike the ribbon, dotting the paper. Typical resolution 80-120 dpi. May have many lines in parallel, making a matrix of pins
• ink-jet and bubble-jet printers tiny blobs of ink sent from print head to paper: ink-jet squirts them, bubble-jet uses heat to create bubble. Quiet. Typically at 300 dpi or better.

Fonts Font refers to the particular style of text. Typical fonts are Courier font Helvetica font Palatino font Times Roman font  (special symbol)special symbol) The size of a font is measured in points (pt), about 1/72”, and is related to its height. This is ten point Helvetica This is twelve point This is fourteen point This is eighteen point and this is twenty-four point

Page Description Languages Pages can be very complex, with text in different fonts, bitmaps, line illustrations, digitised photographs, etc. Can be produced by converting all the information into a bitmap and sending that to the printer, but this is often a huge file. Alternatively, a complete description of the page can be sent, specifying how to draw the graphics and write the text in the desired fonts. This approach uses a page description language : a programming language for printing. Contains instructions for drawing curves, lines, text in different styles, scaling information and so on. PostScript is the most common

Dot Matrix Printer

• (^) Impact printer
• (^) Used to print to multi-sheet pages
• (^) Print head strikes inked ribbon
• (^) Speed measured in characters per second
  • (^) 50-500 cps
• (^) Resolution depends on number of pins on a print-head. More

pins  greater resolution

Other Impact Printers

– Line printers

• (^) Print entire line using

large print head

• (^) 3000 lines/minute

– Band printers

• (^) Uses revolving band

embossed with

alphanumeric

characters

• (^) 2000 lines/minute

Dots per Inch (dpi)

Laser printer

• (^) Non-impact printer
• (^) Produces high quality documents
• (^) Color or black and white
• (^) Print process
  • (^) Laser draws text on drum creating an electrical charge
  • (^) Toner, tiny ink particles, sticks to drum at charged points
  • (^) Toner transferred from drum to paper using pressure and heat
• (^) Color Printing
  • (^) Same process four times
  • (^) Different toner color each time
  • (^) CMYK http://www.techfuels.com/printer/10515-laser-printer-operation.html

Comparing Printers

• (^) Determine what you need
• (^) Determine what you can spend
• (^) Initial cost
• (^) Cost of operating (ink toner + maintenance)
• (^) Image quality (dpi)
• (^) Speed (ppm)

High Quality Printers

• Special purpose printers

– Used by a print shop

– Output is professional grade

– Prints to a variety of surfaces

High Quality Printers

• Thermal wax printers

– Produces bold color output

– Color generated by melting wax which is

transferred onto the paper where it cools

– Requires special coated paper

– Operation costs are low

– Output is slow

– Used for transparencies and handouts

High-Quality Printers

• Dye sublimation printers

– Produces realistic output

– Very high quality

– Color is produced by evaporating ink from the

ribbon and transferring it onto the paper where it

solidifies

– Operation costs are high

– Output is very slow

References

• Chapter 2 and 3 of Peter Norton

Power Supply

• The power supply acts as a step-down

transformer converting high voltage AC

into 5, 12, and 3.3 V DC

– PCs use a 12V current to power motors on devices

such as the hard drives, and CD-ROM drives

– PCs use a 5-volt/3.3-volt current to support

onboard electronics

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