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Presentation on theme: "Printers."— Presentation transcript:

1 Printers

2 Impact Printers Dot Matrix Daisy Wheel

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.

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 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 funtions.

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

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

20 Side View

21 Step 1: Cleaning

22 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

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

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

25 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

26 Step 4: Developing Toner is placed onto the drum where the charge has been reduced

27 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

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

29 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

30 Step 6: Fusing Heat and pressure fuse toner to paper

31 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

32 The End

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