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How does a photocopier work?

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Quick answer

A photocopier uses a light-sensitive drum, static electricity and toner powder. Light reflected from the original removes charge from parts of the drum, toner sticks to the charged areas, and the powder is transferred to paper and melted on with heat. The drum is then cleaned and recharged for the next copy.

A photocopier works by using static electricity to attract toner powder onto a light-sensitive drum, then transferring that powder to paper and fusing it with heat. The process repeats for each copy, with the drum recharged and cleaned for the next page.

Step by step

  1. A corona wire deposits a uniform positive static charge across the surface of a rotating photosensitive drum.
  2. Light reflected from the original document strikes the drum, removing charge from the bright areas and leaving a charge pattern.
  3. Negatively charged toner particles are attracted to the remaining positively charged areas, forming a powder image on the drum.
  4. A sheet of paper receives a strong opposite charge, so when it meets the drum the toner jumps onto the paper.
  5. Heated rollers melt and press the toner into the paper, fusing the image permanently.
  6. A cleaning blade removes leftover toner and the drum is recharged, ready for the next copy.

Key things to understand

  1. A photosensitive drum is given a uniform positive static charge by a corona wire.
  2. An image of the original is projected onto the drum, and light removes charge from the areas it hits.
  3. Oppositely charged toner particles stick to the remaining charged areas, forming a mirror image on the drum.
  4. A sheet of paper is given a stronger opposite charge, pulling the toner from the drum onto the paper.
  5. Heat and pressure rollers melt and press the toner into the paper, creating a permanent copy.

Labelled diagram

  1. Charging

    A corona wire sprays positive charge evenly onto the rotating drum surface.

  2. Exposure

    Light from the original removes charge where the image is white.

  3. Developing

    Negatively charged toner sticks to the charged image areas on the drum.

  4. Transfer

    Paper with a stronger opposite charge pulls the toner off the drum.

  5. Fusing

    Heat and pressure rollers melt the toner permanently into the paper.

  6. Cleaning

    A blade scrapes leftover toner and the drum is recharged for the next copy.

Xerographic copying process

Real-world examples

  • An office worker places a contract on the glass, presses copy, and within seconds a warm, dry duplicate emerges from the tray.
  • A school teacher duplicates a worksheet for thirty students, using the same drum and toner cartridge for every page.
  • A library patron copies a page from a reference book, pressing the lid down so the gap around the book does not print as a dark border.
  • A print shop runs a high-speed digital press that uses the same xerographic process to produce thousands of pages per hour.

Common mistake

✗ Myth: A photocopier takes a photograph of the page and prints it like a camera.

✓ Fact: It does not form a permanent photograph. Instead, it creates a temporary electrostatic image on a reusable drum, transfers dry toner to paper, and melts the toner in place with heat.

People also ask

How does a photocopier make copies?
It charges a photosensitive drum, exposes it to light reflected from the original, and lets toner stick to the charged image areas. The toner is then transferred to paper and fused with heat, while the drum is cleaned and recharged for the next page.
What is the difference between a photocopier and a printer?
A photocopier scans and copies a physical document directly using a lamp and lens, while a printer receives digital data from a computer. Many modern office machines combine both functions, using the same xerographic drum and toner system.
Why does a photocopier get hot?
The fuser rollers inside a photocopier are heated to melt toner powder onto paper, so the machine stays warm during use. Ventilation fans and standby modes help control the heat, and the fuser area can remain hot after copying stops.
Why does a photocopier need a drum?
The drum is a reusable surface that can hold a static-charge pattern and release it after each copy. Its photosensitive coating loses charge where light hits, so it converts an optical image into an electrical pattern that toner can follow.
What is toner made of?
Toner is a fine powder of plastic particles mixed with black or coloured pigment. The plastic melts during fusing, binding the pigment to the paper fibres so the image does not rub off.
Why does photocopying make a bright flash?
The flash is a lamp that briefly illuminates the original document. Its light reflects onto the drum, erasing charge from the areas that should stay white and leaving charge where the black text is.
Can a photocopier copy a copy?
Yes, but each generation loses some sharpness because small dots and grey tones may not reproduce exactly. The machine scans the previous copy as a new original, so contrast and fine detail can degrade over repeated copies.

Part of the guide: Everyday Machines →