You can freely build on How Laszlo Biro Invented the Modern Ballpoint Pen

What this patent covers

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 is now free to use

All 0 claims of US 2390636 are in the public domain. Specifically:

The 0 dependent claims add narrowing limitations and are also free.

What is NOT covered

Patent expiry frees this specific invention. Separately-patented improvements made after expiry may still be protected.

• 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.

Who is building on this today

Companies like Bic, Parker, and Pentel continue to refine the ballpoint mechanism, focusing on ink chemistry and ergonomic housing designs. The core mechanical principle remains the standard for the vast majority of pens sold globally today.

Products built on expired version of this technology

How to cite this patent in your documentation

Individual. US Patent 2390636. Writing instrument. Granted 1945, expired 1963. Now in the public domain.

Note: This is a convenience citation. Consult a patent attorney for formal freedom-to-operate analysis.

PatentBrief is an educational resource and does not provide legal advice. Patent expiration information is derived from USPTO records and may not reflect continuation patents, divisional filings, or separately-patented improvements. For commercial use or production decisions, obtain a formal freedom-to-operate (FTO) opinion from a registered patent attorney.