Foreign object detection covers methods for identifying metal or other objects sitting between a wireless power transmitter and receiver coil before they overheat. In this dataset the core approaches include quality-factor method sensing, power-loss accounting, thermal sensing, and coil-array detection-sensitivity tuning. Most of these are claimed as control-circuit or coil-geometry inventions rather than as separate sensor hardware, which is why the majority of records classify under power supply systems (H02J) rather than imaging or measurement classes.

Filing is concentrated at the top: the five leading assignees together hold 47.2% of the 271 records in scope, rising to 64.2% across the ten leading assignees. Beyond that, a long tail of smaller filers holds the remaining share, drawn from a ranked list of 46 companies in total. No single company controls the field outright, even though the leading assignee holds a clear volume advantage over the rest.

Filings peaked at 34 in 2022 and had fallen to 9 by 2024, a 65% decline from the 26 filings recorded in 2021. That looks like a slowdown, but publication typically lags actual filing by around 18 months, so the 2025 and 2026 counts in any dataset are understated and should not yet be read as confirming a continued decline. The safer read is that activity cooled from its 2022 peak through the last fully reported year.