# Chester Carlson's Original Xerography Patent

> Chester Carlson's 1942 patent for xerography, the dry copying process that became the foundation for Xerox machines.

- **Patent:** US 2297691
- **Original title:** Electrophotography
- **Owner:** Individual
- **Granted:** 1942
- **Status:** Public domain (expired)
- **Times cited:** 737
- **Field:** consumer_electronics, software, semiconductors, materials

## What it does

This patent describes the fundamental process of xerography, a method for making dry copies of documents. It involves charging a surface with static electricity, exposing it to an image to create an electrostatic latent image, dusting the charged surface with a dry powder (toner), transferring that powder to paper, and then fusing the powder to make the image permanent. The core idea is using static electricity to attract toner particles to form an image, which is then heated to create a lasting copy.

## What it does NOT cover

- Does not cover wet copying processes
- Does not cover processes that use liquid developers instead of dry powder
- Does not cover methods that do not involve an electrostatic latent image
- Does not cover processes that do not use heat to fuse the toner
- Does not cover digital scanning or printing technologies

## The clever bit

Carlson's genius was in combining several existing scientific principles—photoconductivity, electrostatics, and powder adhesion—into a single, practical process for image reproduction that was far simpler and faster than existing methods.

## Real-world examples

1. Early Xerox copiers
2. Modern office document printers
3. Laser printers
4. Photocopiers

## Why it matters

This patent is the bedrock of modern document copying. Chester Carlson's invention of xerography directly led to the creation of Xerox Corporation and revolutionized office document reproduction, making fast, dry copies accessible to businesses worldwide.

## Frequently asked questions

### What does Chester Carlson's Original Xerography Patent cover?

Chester Carlson's 1942 patent for xerography, the dry copying process that became the foundation for Xerox machines.

### Who owns patent US 2297691?

Individual owns this patent, granted in 1942.

### When does this patent expire?

This patent has expired and is now in the public domain — anyone can use the invention freely.

### What is patent US 2297691 cited by?

This patent has been cited by 737 later patents that build on its ideas.

### What problem does this patent solve?

This patent is the bedrock of modern document copying. Chester Carlson's invention of xerography directly led to the creation of Xerox Corporation and revolutionized office document reproduction, making fast, dry copies accessible to businesses worldwide.

### What does this patent NOT cover?

Does not cover wet copying processes

**Full plain-English explainer:** https://patentbrief.org/patent/us/2297691/xerography-electrophotography-photocopier

**Original patent:** https://patents.google.com/patent/US2297691

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_Source: PatentBrief — https://patentbrief.org. Patent facts are from public records; the plain-English explanation is PatentBrief's._


## Related patents

Semantically similar inventions in the PatentBrief corpus:

- [How Laser Printers Use Rotating Mirrors to Write Information](https://patentbrief.org/patent/us/3867571/laser-printer-starkweather) — A 1972 Xerox patent describing how to use a spinning mirror to scan a laser beam across a page, adjusting the speed of the data to keep the image sharp.
- [The First Digital Camera's Core Technology](https://patentbrief.org/patent/us/4131919/digital-camera-electronic-still) — Kodak's 1978 patent on the fundamental technology for capturing, processing, and storing digital images using a CCD sensor and magnetic tape.
- [Tiny Capsules for Electronic Paper Displays](https://patentbrief.org/patent/us/5961804/e-ink-electronic-paper-display) — MIT's 1999 patent on a special ink made of tiny capsules that can change color when an electric field is applied, forming the basis for early e-readers.
- [How Organic Diodes Make Light Using Special Molecules](https://patentbrief.org/patent/us/4356429/oled-organic-light-emitting-diode) — Eastman Kodak's 1982 patent on creating light-emitting diodes (OLEDs) using organic materials, specifically a layer of porphyrinic compounds to help inject electrical charges.
- [How Piezoelectric Inkjet Printing Works](https://patentbrief.org/patent/us/3946398/drop-on-demand-inkjet) — A 1970 patent describing how to print images by using electrical pulses to bend a tiny crystal plate, squeezing individual ink drops out of a nozzle on demand.