Capacitive patient presence monitor
US5410297A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 11, 1993 |
| Grant date | Apr 25, 1995 |
| Priority date | — |
| Expiry date | Jan 11, 2013 |
Classification
- Technology area (CPC A)Human Necessities
- CPC primaryA61B2562/0214
- WIPO fieldMedical technology
- WIPO sectorInstruments
Abstract
A capacitive sensor pad includes a foam plastic pad and heavy aluminum foil plates located to the opposite side thereof. The plates are adhesively bonded to the inner surfaces of an outer cover. The capacitor of the pad is connected in circuit with an oscillator and produces a frequency-related output. A ripple counter establishes a frequency-related output proportional to the capacitance. A microprocessor reads the counter output and a plurality of samples are averaged to establish a reference base and the true weight affect of the patient on the sensing pad. Other factors which might effect the signal are readily attended to by programmed compensation. Each subsequent sample is averaged and compared with the reference base. If within a permitted range, the latest and current signal is averaged with the reference base and establishes a new base, and continuously tracks changes in the sensing system. A selected change in a selected time delay system by requiring a series of alarm states or immediately if advance warning is desired, actuates an alert or alarm system, which requires positive resetting to terminate the alarm system. The system is positively reset to return to normal p…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.