Patent websites vary in coverage. Some only have full text or images for recent years. Some have better quality images than others. In some search engines, keywords only work on recent years. If you are doing a full, deep, and serious search, be sure to identify and search on the patent classifications as well as keywords. There are three types of U.S. patents:
Utility
May be granted to anyone who invents or discovers any new and useful process, machine, article of manufacture, or composition of matter, or any new and useful improvement thereof. Utility patents are the most common type of patent and protect an invention for 20 years.
Example: Eye tracking apparatus configured for degrading iris authentication (US11079843B2)
Design
May be granted to anyone who invents a new, original, and ornamental design for an article of manufacture. Design patent numbers start with D and are protected for 14 years.
Example: Wiper blade ornament (USD707612S1)
Plant
May be granted to anyone who invents or discovers and asexually reproduces any distinct and new variety of plant. Plant patent numbers start with PP and are protected for 20 years.
Example: Blueberry plant called Emerald (USPP12165P2)
...and patents include definitions of terms used. Remember, though, that patents are written by attorneys and not by inventors!
