Printers

1. Printers

2. Impact Printers • Dot Matrix • Daisy Wheel • LOUD

3. InkJet Printers • Eject Ink through tiny tubes called jets. • Usually there are four ink wells: Cyan, Magenta, Yellow and Black • Resolution: How close the little dots can be • Speed: pages per minute. B&W usually faster than color

4. Dye Sublimation Printers • AKA thermal dye transfer • Used in high-end applications (photos, publishing, medical) • Continuous tone • Rivals photo lab processing from negative film

5. Laser Printers • Electro-photographic Printing • Uses photo-conductive materials to “etch” an image using a laser beam. • Very high quality print and graphics. • Usually black and white. Magic

6. Toner Cartridge • Contains Toner!!! • Also contains many other parts: • Photosensitive Drum • Primary Corona (Charging Roller) • Developing Cylinder

7. Photosensitive Drum • Aluminum cylinder • Coated with photosensitive particles • Cylinder is grounded, particles are not. • Particles are charged. • When laser strikes the photosensitive drum, the charged particles “escape” to the grounded cylinder

8. Erase Lamp • Exposes all of the photosensitive drum to light. • Leaves drum electrically neutral (i.e. ground)

9. Primary Corona • Very Close but not touching the Photosensitive Drum • Handles extremely high voltage. • Transfers a uniform negative voltage (-600 to -1000 Volts) to Photosensitive Drum

10. Toner • Toner is plastic covered iron • Toner is charged (via developing cylinder) to about -200 Volts • Toner is uniformly distributed on the developing cylinder (held there by magnetism. • Toner is attracted to photosensitive drum where laser has hit.

11. Laser Printing Large Block

12. Transfer Corona • Charges the paper to attract the toner from the photosensitive drum. • This is usually a very thin wire applying a positive charge to the paper. • Prone to getting dirty. • Must be cleaned • Very fragile. DON’T BREAK!!!!!!

13. Fuser Assembly • Consists of two slippery (Teflon) rollers (sometimes hidden) and a heater. • One roller is heated, presses down on the paper, melts the toner into the paper.

14. Other Parts • Turning Gears: moves the paper and rollers • Power Supplies: primary power runs motors, electronics and transfer corona. High voltage Supply for primary corona. • System Board: processor, RAM, ROM, BIOS, Control Circuits • Ozone Filter: eliminates O3 • Sensors/Switches: monitors status. Stops Fires

15. Printer Languages • ASCII: American Standard Code for Information Interchange (Text and control)ascii.txt • PostScript: created by Adobe. Printer independent language. Strengths were high resolution graphics and scalable fonts. sigcse97.txt • Printer Control Language: created by HP. Originally for text. PCL6 supports scalable fonts and drawing functions.

16. Graphical Device Interface • Microsoft print handling component • Uses the CPU (not the printer) to process a print job. • Sends a “Raster” image to the printer.

17. Printer Connections • Parallel Port: Uses special cable to connect 25-pin printer port on computer to 36-pin Centronics port on printer. • USB: Plug and Play??? • InfraRed • Bluetooth • Network

18. IEEE 1284 Standard • Specifies Cable and Electronics configuration. • Centronics Mode: One way 8-bits • Nibble mode: uses status wires to send 4-bit data back to computer • Byte Mode/BiDir: enables half-duplex 8-bit communication • Enhanced Parallel Port: Offloads overhead to parallel port away from CPU. • ECP: uses DMA and data compression (run length encoding)

19. Wireless Printers • InfraRed: • Must be close (1 meter) • Slow: 10 kbs • Bad in “noise” • Bluetooth • Better: 10 meters, 1-3Mbps • Not Better: Security

20. Six Steps of Laser Printing • Cleaning • Charge/Condition • Writing • Developing • Transferring • Fusing • Take place inside toner cartridge • Use components that undergo the most wear

21. Side View

22. Step 1: Cleaning

23. Step 1 Mind-Numbing Detail • Sweeper strip cleans the drum • Remove/swept away by Sweeping blade • Cleaning Blade finishes physical cleaning • Erase lamps remove electrical charge

24. Step 2: Conditioning • Primary Charging Roller conditions drum to contain a Uniform high electrical charge (-600 V)

25. Step 3: Writing • Laser beam discharges a lower charge to only those places where toner is to go

26. Writing Mind-numbing Detail • Uniform charge is discharged only where the laser beam hits (due to photosensitivity) • Mirrors reflect the laser beam onto the Drum • Scanning Mirror directs beam across the page • Main mirror(as wide as the page) reflects beam onto drum through a slit • Focusing lens sharpens the image • Beam detect causes DC controller to step the drum and start a new scan

27. Step 4: Developing • Toner is placed onto the drum where the charge has been reduced

28. Developing Mind-numbing Detail • Charged (~-300V) Toner (resin coated iron) is attracted to the developing cylinder magnetically • Control blade creates even distribution • Charged Toner is pulled off developing cylinder onto drum • Toner is charged by DC bias on Dev.Cyl. The amount of bias controls density

29. Step 5: Transferring • Strong electrical charge draws toner off drum onto paper; takes place outside the cartridge

30. Transfering • As paper is feed to roller a transfer charging roller creates a positive charge • As paper passes by drum, the toner is drawn to the positively charged paper • After paper passes roller the static charge eliminator reduces the charge on the paper and the drum

31. Step 6: Fusing • Heat and pressure fuse toner to paper

32. Fusing Mind-numbing detail • Fusing roller apply heat and pressure. • Toner melts into paper • If temperature exceeds 410 degrees F the fusing system shuts down

33. The End