Laser Printers

What Is A Drum Unit?

Laser printers can dish out quality printouts at faster speeds than inkjets. This is the primary reason why these are widely used in demanding working environments. Laser printers are commonly used for document printing. Moreover, the significant developments in laser printing technology such as colored toner formulation enabled printing in color to prosper tremendously.

One of the key components in high quality laser color prints is the printer drum unit. Despite its important function, not many users are in the know of its role in laser printer operation.

What Is A Drum Unit

Definition – What is a drum unit?

The printer drum unit is an important print component. Its primary role is to attract the toner particles by way of electrostatic polarities. Also known as image units, the design of the drum vary depending on the printer model and brand.

More tips and tricks to printer maintenance and how you can save on printing supplies from the Printer Encyclopedia.

Recent models make use of toner cartridges with built-in drum units. The combination cartridge and drum set up allows the printer to operate at better print speeds. This is because the cartridge and drum unit can sync better and therefore operate at reduced response times as compared to printers loading a separate toner cartridge and image unit. However, combination cartridges are not cost-efficient in the long run. In most cases, the drum unit is still serviceable when the cartridge’s toner supply runs out. Thus, a working drum unit gets disposed with the empty toner cartridge.

Function – How Does It Work?

The laser printer drum operates as the photo conductive unit which serves as the image processing core. Basically, it is a set of parts that specifically work to transfer and paint a digital image right into the surface of the drum. The document to be printed is transformed into a raster image by the computer and sent into the printer. These processes take place during printing.

Charging the Drum – The printer drum unit will be positively charged. The electrostatic character of the drum unit can be achieved in 2 different ways depending on the printer mechanism. Some printers use a corona wire with electric current running through it. The newer printers use a separately charged roller instead of the corona wire. These are two completely different ways to charge the drum unit but both basically follow the same principle.

Recreating the Image – Tiny laser beams from the printer laser scanning unit draw patterns on the surface of the drum unit to recreate the image. Initially, the surface of the drum and the toner particles have positive polarities.

As the drum rotates, the laser beam is used to paint the image or texts. Through the action of the laser beam the formed image becomes negatively charged, thus allowing the positively charged toner to cling to the surface of the drum. Excess toner is then wiped away by the laser drum cleaning blade to guarantee the best printout quality.

Transferring Image to Medium – Toner on the printer drum unit will then be transferred to the medium which is usually paper or transparency. Once complete, toner and paper moves into the fuser roller for final bonding. The printout will come out a little warm but smudge-proof.

fuction of drum unit

Importance – Can The Laser Printer Function Without It?

Laser printers rely on the printer drum unit in creating and transfusing images into the medium. This means that without it, the printer will not be able to produce any printout. While toner cartridges are important, it is the drum that makes printing possible.

Frequency of Replacement – How often do drums need to be replaced?

Laser printer drum units like toner cartridges have finite shelf life. Most image unit last 2 to 3 toner cartridges or refills but they eventually wear off. The laser printer will turn out poor quality prints even after replacing or refilling the toner cartridge when a defective or exhausted drum unit is used. Replacing the drum in this scenario is therefore necessary.

Compatible Consumable – Are There Cheaper Alternatives?

OEM printer parts are usually very expensive. Consumers can opt for cheaper alternatives such as a compatible drum unit or compatible drum assembly depending on the printer model.

Is the OPC drum of your laser printer worn out? Shop for a compatible replacement now at and enjoy big savings.

Compatible drum units are aftermarket replacements for non combination cartridges where the drum unit is unattached to the cartridge. The compatible drum assembly on the other hand replaces the drum of combination cartridges or toner cartridges with built-in drum units. Both are more affordable options to OEM counterparts but offer different levels of cost-efficiency.

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