San Diego's e.Digital Corp. (OTCQB: EDIG), a one-time tech pioneer that has recently made much of its money by suing over alleged patent infringement, has filed an infringement suit against security camera makerDropcam in U.S. District Court in San Diego.

The suit alleges that Dropcam's system is based on e.Digital's "Nunchi patents," which cover the use of devices to communicate and monitor remote locations.

"We are starting to see products introduced that exhibit reliance on the teachings of our Nunchi patent portfolio," said e.Digital CEO Fred Falk. "The Dropcam product is an example of this."

E.Digital, which pioneered flash memory technology and portable in-flight systems more than 20 years ago, has recently made the bulk of its money through patent lawsuits.

In filings with the Security and Exchange Commission last month, it reported it made more than $2 million in 2013 through one-time, non-recurring patent payments, typically tied to legal settlements, versus $253,373 in product services and revenues. It spent $757,737 in litigation, contingent legal fees and patent costs, more than twice as much as the $354,720 it reported for research and development.