Chester Carlson's xerography uses a charged drum to attract toner where light has discharged it. The office printer in your hallway.
A laser draws your image in static electricity on a drum; toner powder sticks to the static and is melted onto paper by heat.
- ▸Toner is plastic dust, not liquid ink.
- ▸Heat fuses it to the page — that's why fresh prints feel warm.
- ▸Fast and sharp, but black-and-white machines can't match photo-quality color.
History
Carlson invented electrophotography in 1938; Xerox commercialised the 914 copier in 1959. HP launched the LaserJet in 1984, bringing the technology to desktops.
Process
- 01
Laser scans an image onto a charged photoconductor drum.
- 02
Discharged areas attract oppositely-charged toner powder.
- 03
Drum rolls toner onto paper passing beneath.
- 04
Heated fuser rollers melt toner into the fibres.
- 05
Output exits sealed and dry.
Strengths
- +Fast, dry, cheap per page
- +Sharp text
- +Low maintenance
Limitations
- −Limited paper textures
- −Toner can crack on folds
- −Less vivid than inkjet for photos
Sources & citations
References for the history and process described above.
- 01Xerography and the Laser Printer — Computer History Museum
- 02Chester Carlson and the Birth of Xerography — Smithsonian — Lemelson Center