You can freely build on How Percy Spencer Invented the Microwave Oven
This patent expired in 1967. Every claim — 1 independent, 0 dependent — is now unenforceable. Anyone can use, reproduce, manufacture, sell, or offer for sale this technology without a license.
Original assignee
Raytheon Manufacturing Co
Patent granted
1950
Expired
1967
Forward citations
20
What this patent covers
The patent outlines a method for cooking food by generating electromagnetic waves specifically in the microwave range. It requires guiding and concentrating these waves into a restricted, enclosed space where the food is placed. By exposing the food to this concentrated energy for a specific duration, the internal temperature of the food rises, effectively cooking it.
What is now free to use
All 1 claims of US 2495429 are in the public domain. Specifically:
Claim 1: IN THE METHOD OF TREATING FOODSTUFFS, THOSE STEPS WHICH INCLUDE: GENERATING ELECTROMAGNETIC WAVE ENERGY OF A WAVELENGTH
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 the specific electronic circuitry or magnetron design used to generate the waves.
Does not cover methods of cooking that use infrared radiation or traditional convection heat.
Does not cover the use of microwave energy for non-food applications like telecommunications or radar.
Who is building on this today
Raytheon, the original assignee, pioneered the first commercial units. Today, major appliance manufacturers like Samsung, LG, and Whirlpool continue to refine the efficiency and control systems of microwave cooking technology.
Products built on expired version of this technology
Amana Radarange
Modern household microwave ovens
Industrial microwave food processing equipment
How to cite this patent in your documentation
Raytheon Manufacturing Co. US Patent 2495429. Method of treating foodstuffs. Granted 1950, expired 1967. 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.