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What exactly is a drum in a printer?

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What exactly is a drum in a printer?

Old 04-19-02, 03:14 PM
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What exactly is a drum in a printer?

What is it's purpose?
Old 04-19-02, 03:19 PM
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I assume that your referring to a laser printer drum. It does most of the mechanical work of the printer. They are so expensive it's usually cheaper to buy a new printer when it breaks. Some new laser printers come with parts of the drum built into the toner cartridge so the wearing drum parts gets replaced every time you get a new toner.
Old 04-19-02, 03:27 PM
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From About.com:

Laser Printer - Definition: A laser printer uses methods similar to a photocopier to print computer output on paper. The printer uses light rays from a laser or LED array to write the output on an electrically charged drum; regions of the drum hit by the light are discharged, while the rest of the drum remains charged. The drum then picks up powdered toner only on discharged portions. The toner is deposited on the paper, then fused and bonded to the paper surface with a heated roller. Color laser printers mix several colors of toner in a multi-pass process. Laser printers have their own command language; most use Adobe's Postscript or Hewlett-Packard's PCL language. Laser printers connect to the computer via parallel port, USB port, or an integrated network adapter.

Thats the best I could find.
Old 04-19-02, 03:52 PM
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Originally posted by Ben732
From About.com:

Laser Printer - Definition: A laser printer uses methods similar to a photocopier to print computer output on paper. The printer uses light rays from a laser or LED array to write the output on an electrically charged drum; regions of the drum hit by the light are discharged, while the rest of the drum remains charged. The drum then picks up powdered toner only on discharged portions. The toner is deposited on the paper, then fused and bonded to the paper surface with a heated roller. Color laser printers mix several colors of toner in a multi-pass process. Laser printers have their own command language; most use Adobe's Postscript or Hewlett-Packard's PCL language. Laser printers connect to the computer via parallel port, USB port, or an integrated network adapter.

Thats the best I could find.
That definition is acurate for the most part.

The drum could be compared to a plate in offset (ink) printing. It's what carries the image to be printed.

The reason it wears out and needs replacing is it is constantly being bombarded with light and high voltage (usually in the -650volt rang) this wears down the photo sensitivity of the drum surface (usually made from selenium).

Basically it works like this...

Step 1: The drum is charged to around negative 650 volts.

Step 2: The drum is then exposed by either LEDs or a laser using a scanning mirror to create the image. The exposed image is now at around -500 volts.

Step 3: The toner is negatively charged to around 650 volts and the toner is attracted to the lesser charged image on the drum from step 2.

Step 4: The paper is then charged positively and the toner is pulled off the drum onto the paper.

Step 5: The toner (which is made from plastic) now on the paper goes through the fuser unit which melts the toner onto the paper.

Step 6: The drum is cleaned off by a clean bar charged at a higher voltage then the drum and by brushes and it is ready for the next page.

Last edited by palebluedot; 04-19-02 at 03:56 PM.
Old 04-19-02, 04:00 PM
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Interesting.

We have an HP 4500N printer, and looks like the drum will cost somewhere between $79 at CDW and $445 at Corporate Express. (some preferred vendor!)
Old 04-19-02, 07:31 PM
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Originally posted by ChiTownAbs
Interesting.

We have an HP 4500N printer, and looks like the drum will cost somewhere between $79 at CDW and $445 at Corporate Express. (some preferred vendor!)
Does the one at Corporate Express come with anything?! Like a PRINTER?!
Old 05-03-02, 10:14 AM
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For my last printer the drum units cost about $165 and last maybe 2 years under light use if I'm lucky. This is why I recomment not buying any Brother printers (toner outlasts the drum). My new Laser printer (Lexmark) cost less than a drum for my Brother printer and the toner cartridge unit, while a bit pricy, it does contain all the drum parts that normally wear out so I won't ever have to replace an expensive drum again (I hope).

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