A belt-mounted keyholder with magnetic presence sensors and wireless alarm
A host (belt) unit physically receives a removable remote unit that attaches to an item such as a set of keys. Each unit has a magnetic sensor to sense direct contact; the host and remote also communicate wirelessly and monitor signal quality so an alarm sounds when separation exceeds a threshold. Intended users are people who carry keys or other small security items and want an audible alert if the item is detached or moved away from the wearer.
(57) What the patent covered
This write-up was generated by AI from the patent's text and may contain mistakes, so check it against the original patent before relying on it.
The independent claims require a host unit that receives a removable remote unit, a magnetic sensor on each unit that independently detects direct contact or its absence and triggers an initializing function, and wireless communication between host and remote that uses signal quality to judge separation and to alarm when a threshold is exceeded.
Distinguishing feature: Using paired Hall-type magnetic sensors to detect physical presence at the host/remote interface combined with wireless signal-strength monitoring to determine an alarm distance.
Novelty 3/5. Key fob alarms and wireless proximity alerts were already common; the patent added the specific combination of direct-contact magnetic sensing plus rolling-average signal-quality separation detection.
Manufacturing
Injection-molded plastic housings, PCB assembly with surface-mount components, press-fit Hall sensors, ultrasonic welding or screws for assembly, final hand assembly to insert batteries and mate host/remote.
Materials: ABS or polycarbonate thermoplastic housing, Small PCB with RF transceiver (ISM band) and microcontroller, Hall-effect sensors (IC), Buzzer or piezo alarm, Metal keyring or polymer attachment.
Manufacturability 4/5. Few molded parts and standard PCBs; requires RF module sourcing and simple assembly of electronics and housings but no precision optics or firmware complexity beyond low-power radio and sensor logic.
Market demand
No demand check has been run for this patent. Likely search terms: belt key holder alarm, key fob separation alarm, proximity key holder with magnetic sensor. The links in the sidebar open these searches.
Buyers: People who carry keys or ID badges.
Before manufacturing
No related continuation or divisional patents in force were found. Design patents, trademarks and unrelated patents may still cover the product.
None obvious; practical risks include crowded market of key-finder/proximity devices and the patent is lapsed but its claims were specific to paired magnetic presence sensing plus wireless RSSI-based separation.
About 1.5% of lapsed patents are later revived by their owners. This page is a research lead, not legal advice. Obtain a freedom-to-operate opinion before manufacturing.