The Six Steps of Laser Printing
From Data to Fused Toner
1 Purpose
The laser printing process is one of the most complex and important hardware topics for the CompTIA A+ exam. Understanding each of the six steps in the electrophotographic process is essential for diagnosing print quality issues. This document breaks down the entire process, from cleaning the drum to fusing the toner onto the page.
2 What You’ll Accomplish
By the end of this reading, you will be able to:
- List the six major steps of the laser printing process in the correct order.
- Describe the key action that occurs during each step.
- Identify which components are involved in the transferring and fusing stages.
This reading maps to the following program and course learning outcomes:
- Course Learning Outcomes (CLOs):
- 1. Identify hardware and basic network components: This topic provides a deep dive into the internal mechanics of a laser printer, a complex hardware peripheral.
This exercise develops the following skills, which align with the O*NET SOC Code 15-1232.00 for Computer User Support Specialists.
| Learning Objective | O*NET KSAs | Technologies Used |
|---|---|---|
| List and describe the six steps of laser printing. | Knowledge: Computers & Electronics, Engineering and Technology Abilities: Information Ordering |
Laser Printer, EP Process |
3 The Electrophotographic (EP) Process
The entire laser printing process revolves around the imaging drum, a photosensitive cylinder that can hold an electrical charge.
3.1 Step 1: Cleaning
Before a new page can be printed, the drum must be prepared. A rubber blade physically scrapes any excess toner from the previous print job off the drum’s surface. A fluorescent lamp then discharges any remaining electrical charge from the drum, leaving it completely neutral and clean for the next page.
3.2 Step 2: Conditioning (Charging)
In this step, a special wire or roller called the primary corona applies a strong, uniform negative electrical charge (typically -600V) to the entire surface of the photosensitive drum as it rotates.
3.3 Step 3: Exposing (Writing)
A laser beam, controlled by the printer’s processor, scans across the surface of the charged drum. Everywhere the laser touches, the strong negative charge is neutralized, leaving a “written” area with a much lower negative charge. This creates an invisible electrostatic image of the page on the drum’s surface.
3.4 Step 4: Developing
The drum rotates past the toner cartridge. The toner inside is also negatively charged by a developing roller. Because the toner and the background of the drum have a similar strong negative charge, they repel each other. However, the areas “written” by the laser have a much weaker charge, so the negatively charged toner is attracted to and sticks to these areas on the drum. The invisible electrostatic image is now a visible image made of toner.
3.5 Step 5: Transferring
The sheet of paper is fed into the printer and given a strong positive charge by a transfer corona or transfer roller. As the paper passes underneath the drum, the toner, which is negatively charged, is attracted to the paper’s strong positive charge and “jumps” from the drum onto the paper. The image is now on the paper, but it is held there only by static electricity.
3.6 Step 6: Fusing
This is the final step. The paper, with its loose toner, passes through a fuser assembly, which consists of a pair of hot pressure rollers. The heat melts the toner (which is a fine plastic powder), and the pressure presses it permanently into the fibers of the paper. The finished, waterproof page then exits the printer.
4 Reflect and Review
Now that you have reviewed this document, take a moment to reflect on your learning in your personal notes:
- 3 of the six steps in the laser printing process.
- 2 components that apply an electrical charge (e.g., primary corona, transfer corona).
- 1 question you still have about the fuser assembly.
Answer these questions in your notes to solidify your understanding:
- What is the very first step in the six-step laser printing process?
- During which step does the laser beam write an electrostatic image onto the drum?
- What two forces are used in the fusing stage to bond the toner to the paper?
- What is the purpose of the transfer corona?