You can freely build on How Liquid Crystal Displays (LCDs) Were Invented
This patent expired in 1984. 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
RCA Corp
Patent granted
1967
Expired
1984
Forward citations
90
What this patent covers
The device uses two parallel plates spaced less than 500 microns apart, with the gap filled by an organic nematic mesomorphic compound, commonly known as a liquid crystal. One plate is transparent and the other is reflective, with conductive films on both to allow an electric current to pass through the material. When the electric field reaches a specific threshold, the molecules in the liquid crystal rearrange, causing the material to scatter light. This scattering effect changes the appearance of the display, allowing it to toggle between transparent and opaque states.
What is now free to use
All 1 claims of US 3322485 are in the public domain. Specifically:
Claim 1: AN ELECTRO-OPTICAL DEVICE — 6 specific elements
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 color display technology, which requires additional filters not described here.
Does not cover active-matrix displays (TFTs) that use individual transistors for each pixel.
Does not cover the use of liquid crystals for anything other than light scattering (e.g., polarization-based twisting).
Does not cover backlighting systems, as this design relies on reflecting ambient light.
Who is building on this today
While RCA originally developed this, the technology was rapidly advanced by companies like Sharp, Casio, and later Samsung and LG. Modern display manufacturers continue to build on the fundamental principles of controlling light through liquid crystal orientation.
Products built on expired version of this technology
Early digital watch displays
Calculator screens from the 1970s
Basic monochrome information displays
How to cite this patent in your documentation
RCA Corp. US Patent 3322485. Electro-optical elements utilizing an organic nematic compound. Granted 1967, expired 1984. 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.