You can freely build on The Invention of the Transistor

What this patent covers

This patent describes the first working transistor, a three-electrode circuit element that controls the flow of electricity through a semiconductive material. By applying a small voltage to a control electrode, the device can amplify or switch a much larger current flowing between two other electrodes. This mechanism replaced bulky, fragile, and power-hungry vacuum tubes with a tiny, solid-state component. It effectively functions as an electronic gate, allowing binary data to be processed at high speeds.

What is now free to use

All 0 claims of US 2524035 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 junction transistors, which were developed later and use different internal structures.

• Does not cover integrated circuits, which combine many transistors onto a single chip.

• Does not cover field-effect transistors (FETs) that use an insulated gate structure.

• Does not cover modern silicon-based manufacturing processes like photolithography.

Who is building on this today

Every major semiconductor company, including Intel, TSMC, and Samsung, builds upon the fundamental physics described here. While the specific point-contact design is obsolete, the principle of solid-state switching remains the industry standard.

Products built on expired version of this technology

How to cite this patent in your documentation

Bell Telephone Laboratories Inc. US Patent 2524035. Three-electrode circuit element utilizing semiconductive materials. Granted 1950, expired 1968. 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.