Blood monitoring apparatus and methods with amplifier input dark current correction
US4781195A · kind A · utility
279Cited by
3References
14Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Dec 2, 1987 |
| Grant date | Nov 1, 1988 |
| Priority date | — |
| Expiry date | Dec 2, 2007 |
Classification
- Technology area (CPC A)Human Necessities
- CPC primaryA61B5/02416
- WIPO fieldMedical technology
- WIPO sectorInstruments
Abstract
In photoelectric apparatus such as a pulse oximeter for monitoring a parameter of the blood in a living organism, a dark current correction signal is applied to the input at the preamplifier. The correction signal is substantially equal in magnitude but opposite in sense to the photodetector output during dark intervals when the illumination means of the apparatus is disabled. Because dark current correction is accomplished at the input of the preamplifier, the preamplifier has substantially increased resistance to overloading caused by ambient light and hence may have higher gain.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.