What is a drum unit? Otherwise called the Photoconductive Unit (PCU) is a laser printer component containing the corona wire or separate charge roller and imaging drum. This consumable is purposely responsible for transferring toner to paper. The laser printer puts toner onto the photosensitive drum (roller) and then prints images and letters by setting toner to paper through heat and pressure. The drum unit can either be incorporated with the toner cartridges/s or a separate unit like the Brother DR-400.
How does it work? The Brother DR-400 drum unit for instance rotates to complete several tasks.
- A positive charge from the corona wire allows tiny laser beams to pick up or paint the image to the drum.
- As the positive charge paints the text, the negative charge it produces creates a reversed or negative background.
- The drum unit then attracts the toner through electrostatic. And as the paper passes through the PCU, the toner imprints on the paper with the image it has painted.
- The paper then passes through the fuser unit where the toner is melted and finally creates the final output.
When to replace the drum unit? A drum unit is a consumable; therefore, it depletes overtime. There are mainly two ways to know when the PCU needs replacing.
- An alert or message will appear on the LCD display indicating that the toner level is low along with a beeping sound.
- One of the most obvious indications that a drum unit needs replacing is when the printout quality begins to deteriorate or is defective.
Some users take no heed of the warning sign on the display and keep running the printer with an almost empty or a low toner level. This is not a good practice because it can damage the printer head and could eventually break the machine. It is fully understandable that the users would want to prolong the inevitable because a genuine drum unit is costly. Yet, there are cheaper but dependable options like the remanufactured Brother DR-400 to avoid damaging the printer.