Apparatus for the automatic calibration of signals employed in oximetry
US5259381A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 10, 1989 |
| Grant date | Nov 9, 1993 |
| Priority date | — |
| Expiry date | Jul 10, 2009 |
Classification
- Technology area (CPC A)Human Necessities
- CPC primaryA61B2562/08
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Under the present invention, a method and apparatus are provided for compensating for the effect temperature variations have on the wavelength of light emitted by the oximeter sensor light source (40, 42). In pulse oximetry, LEDs (40, 42) are typically employed to expose tissue to light at two different wavelengths. The light illuminating the tissue is received by a detector (38) where signals proportional to the intensity of light are produced. These signals are then processed by the oximeter circuitry to produce an indication of oxygen saturation. Because current oximetry techniques are dependent upon the wavelengths of light emitted by the LEDs (40, 42), the wavelengths must be known. Even when predetermined combinations of LEDs (40, 42) having relatively precise wavelengths are employed, variations in the wavelength of light emitted may result. Because the sensor (12) may be exposed to a significant range of temperatures while in use, the effect of temperature on the wavelengths may be significant. To compensate for this effect, a temperature sensor (50) is included in the sensor (12) to produce a signal indicative of sensor temperature. This signal is interpreted by the oximet…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.