Hello Steemit!
I'm preparing for my ComptiA+ exam and a lot of topics take me at least a day and sometimes more to understand. However once I've done research about a topic I build a clear and concise picture about it. I will try and digest any new principles that I learn and explain them for easy consumption. Take what you read with a grain of salt. I might be completely off. It is just my interpretation of how certain principles work.
Writing such summaries helps me solidify my understanding of different subjects. Without further ado..
Todays topic: Laser printers.
Always baffling and never understood what actually is going on until now. Here all the steps that happen when you print a page:
- The PC sends the data to the printer controller circuit which processes and translates the bits of instructions to its mechanical parts.
- A ElectroPhotographic (EP) drum gets charged with negative -600V DC static electricity. That happens via a corona wire or most commonly corona drum.
- A laser (thus the term 'laser printer') or a LED, expose light and 'write' the page to be printed line by line on the EP (ElectroPhotographic) drum. By exposing the EP drum to light, it loses 500V of charge. The light exposed areas have a -100V DC charge and the rest -600V DC.
This is in fact the magic of laser printers. You have your entire page not in ink but static electricity! - The printer toner (a mix of polyester, carbon and iron oxide oily dust substance reacting to electricity) also has a roll that is also charged with -600V DC. It interacts with the -100V DC laser exposed parts which allowes the toner 'ink' to stick to the EP drum. There is a 500V DC difference.
- The paper that comes in is charged with positive +600V DC voltage by another corona wire and attracts the toner ink from the -100V DC parts on the paper. Now that's just this an ink-dust substance stuck on paper by static electricity. First the paper gets discharged by a static eliminator strip and next:
- Two fuser rollers fuse the toner 'ink' to the paper. One of the rollers is teflon and aluminium coated that gets heated up by a halogen lamp between 170C - 200C. The other roller is rubber. This literally melts the toner and fuses it with the paper. That's why you get hot pages straight out of the laser printer, not because of the electricity.
- Once the page is out a sensor tells that the EP (ElectroPhotographic) drum can be cleaned. A fluorescent lamp fully discharges the drum and a rubber that touches the drum scrapes any remaining toner off.
The End.