Laser Printers

What are the seven stages of the laser printing process in order?

1. Processing

2. Charging

3. Exposing

4. Developing

5. Transferring

6. Fusing

7. Cleaning

What happens in the processing stage?

The printer receives and processes the image and stores a page and memory

What happens in the charging stage?

The printer place a uniform -600 charge on the photosensitive drum using a charging corona

What happens during the exposing stage?

The laser paints an image onto the photo sensitive drum, discharging the image areas to a much lower voltage -100VDC

What happens during the developing stage?

The developing roller in the toner cartridge has charged -600VDC toner stuck to it

• The toner is attracted and sticks to the areas of the photo sensitive drum that the laser discharged

What happens during the transferring stage?

The images transferred from the drum to the paper via the transfer corona wire with a +600VDC charge

• The static eliminate strip removes the high positive charge from the paper

What happens during the fusing stage?

Paper enters diffuser. A fuser roller and the pressure roller make the image permanent.

• The paper exits the printer

What happens during the cleaning stage?

Printer uses a rubber scraper to clean the photo sensitive drum

• A fluorescent lamp discharges Eny remaining charge on the Photos sensitive drum

• Printer is now ready to print next stage or return to the ready state

What is an imaging drum?

A photo sensitive cylindrical drum coated with a material that holds an electric static charge in the dark but loses it when exposed to light

What is diffuser assembly and why is it hot?

Diffuser bonds toner to the paper using heat and pressure

• Two fuser rollers - a heated roller and the pressure roller

What is the transfer belt/roller and a laser printer?

It applies a positive charge to the paper as it passes beneath the drum

• positively charge paper attract and negatively charged turn off the drum

What components are usually inside a laser toner cartridge?

• The Turner Reservoir, the imaging drum, the developer roller, the doctor blade, and the wiper blade

What is a laser printer maintenance kit and what does it contain?

A set of high-wear components replaced on a schedule based on page count

• Can include a fuser assembly, transfer roller, pick up rollers, separation pad, and transfer belt

• Useful when the cleaning routine is not enough

What does the developer roller do?

Rotates through the toner reservoir, picking up toner particles on its surface

What does the doctor blade do?

A thin flexible strip that scrapes off excess toner ensuring a uniform thin layer on the developer roller before it contacts the drum

How do you safely replace a laser toner cartridge?

1. Power down or open the printer door (whichever pauses drum)

2. Remove the old cartridge

3. Dispose according to manufacturer/recycling guidelines

4. The new cartridge gently to distribute toner evenly

5. Remove ceiling tape/strip if present and then insert firmly until it clicks

What is laser printer calibration?

Aligns the print output to ensure colours margins and registration are accurate

How do you clean the inside of a laser printer?

• Use a turn of vacuum and wipe accessible services with a dry or slightly damp lint free cloth

• Use IPA on a cotton swap for rollers and the transfer area

What does faded/light prints mean?

Low toner or worn developer roller

What do vertical black lines on prints mean?

Scratch on the drum

What do repeating spots at regular intervals indicate?

Defect on the drum or roller

What do smeared/infuse toner indicate?

Fuser failure

What does background scatter (grey haze) indicate?

High humidity, one drum or doctor Blade failure

What do white vertical streaks indicate?

Clogged/worn toner or wiper blade