Which roller applies an electrostatic charge uniformly on the drum in a laser printer?

The primary charge roller is responsible for applying an electrostatic charge uniformly to the photosensitive drum within a laser printer. This initial charging is crucial because it prepares the drum to attract the toner particles that will form the printed text and images. When the primary charge roller contacts the drum, it ensures that the surface of the drum has an even charge, which is essential for the accurate imaging process.

For context, the transfer roller is primarily involved in transferring the toner from the drum to the paper, while the pickup rollers are responsible for feeding paper from the tray into the printer. The fuser roller plays a crucial role in melting the toner onto the paper to ensure it adheres well. Each of these components is vital for the printer's operation, but the specific function of uniformly applying an electrostatic charge is the defining role of the primary charge roller.