# How Laszlo Biro Invented the Modern Ballpoint Pen

> This 1945 patent describes the original ballpoint pen mechanism that uses a rotating sphere to distribute thick, quick-drying ink onto paper.

- **Patent:** US 2390636
- **Original title:** Writing instrument
- **Owner:** Individual
- **Granted:** 1945
- **Status:** Public domain (expired)
- **Times cited:** 30
- **Field:** mechanical, consumer_electronics

## What it does

The patent describes a writing instrument featuring a small, freely rotating ball held in a socket at the tip of a reservoir. As the pen moves across paper, the ball rolls, picking up viscous ink from the reservoir and depositing it onto the writing surface. This design solved the problem of ink leakage and smearing common in fountain pens of the era, as the ball acts as a seal when the pen is not in use.

## What it does NOT cover

- Does not cover pens that use felt or porous fiber tips.
- Does not cover fountain pens that rely on capillary action through a nib.
- Does not cover pressurized ink delivery systems used in specialized space pens.
- Does not cover gel-based ink formulations developed decades later.

## The clever bit

The innovation lies in the combination of a high-viscosity ink and a precision-fitted socket that allows the ball to rotate freely while preventing the ink from drying out or leaking excessively.

## Real-world examples

1. Bic Cristal pens
2. Standard office ballpoint pens
3. Disposable promotional pens

## Why it matters

This invention fundamentally changed how the world writes by replacing the messy, fragile fountain pen with a reliable, mass-producible tool. It enabled the rapid adoption of affordable writing instruments in schools, offices, and military operations during the mid-20th century.

## Frequently asked questions

### What does How Laszlo Biro Invented the Modern Ballpoint Pen cover?

This 1945 patent describes the original ballpoint pen mechanism that uses a rotating sphere to distribute thick, quick-drying ink onto paper.

### Who owns patent US 2390636?

Individual owns this patent, granted in 1945.

### 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 2390636 cited by?

This patent has been cited by 30 later patents that build on its ideas.

### What problem does this patent solve?

This invention fundamentally changed how the world writes by replacing the messy, fragile fountain pen with a reliable, mass-producible tool. It enabled the rapid adoption of affordable writing instruments in schools, offices, and military operations during the mid-20th century.

### What does this patent NOT cover?

Does not cover pens that use felt or porous fiber tips.

**Full plain-English explainer:** https://patentbrief.org/patent/us/2390636/ballpoint-pen-biro

**Original patent:** https://patents.google.com/patent/US2390636

---

_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 Lewis Waterman's Original Fountain Pen Design Worked](https://patentbrief.org/patent/us/293545/fountain-pen-waterman) — This 1884 patent describes an early fountain pen designed by Lewis E. Waterman, which aimed to solve common ink-flow problems, making writing smoother and cleaner.
- [How a Simple Felt-Tip Marker Works](https://patentbrief.org/patent/us/2713176/magic-marker-permanent-marker-rosenthal) — A 1953 design for a handheld marking tool that uses a porous tip to deliver ink from an internal reservoir.
- [How King Gillette Invented the Modern Disposable Safety Razor](https://patentbrief.org/patent/us/775134/safety-razor-gillette) — King Gillette's 1904 patent for a safety razor with a thin, replaceable, double-edged blade that changed how the world shaves.
- [How Jacob Schick Invented the Modern Magazine-Loading Safety Razor](https://patentbrief.org/patent/us/1721530/schick-repeating-razor) — A 1929 patent for a safety razor that uses a replaceable blade magazine, allowing users to change blades without touching the sharp edges.
- [How the Modern Disposable Paper Cup Was Invented](https://patentbrief.org/patent/us/1032557/dixie-cup-disposable-paper-cup) — A 1908 patent for a sanitary, single-use paper cup designed to prevent the spread of germs from shared public drinking vessels.