Timothy Allen Shotter

51350025, Aug 4, 1992

Aug 29, 1989

7/400274

Richard A. Kirchner - Santa Clara CA
Timothy A. Shotter - Sunnyvale CA
Robert W. Beard - late of Placerville CA

Abbott Laboratories - Abbott Park IL

A61B 500
G01L 2700

128672

A pressure transducer compensation system for compensating an offset and adjusting the sensitivity of the pressure transducer to a predetermined level. A reusable cable (160) connected to a pressure monitor (14) is intended for use with a plurality of disposable pressure transducers (12). In one embodiment, a connector (150) of the reusable cable includes a CPU (70), which determines the offset and self-heating errors of the pressure transducer during the first 30 seconds it is energized, stores the corrections in its internal memory and compensates the output signal produced by the pressure transducer for those errors and for variations in ambient temperature. A gain-set resistor (56) is included in a male modular phone plug (202) of a disposable cable that is integrally connected to the pressure transducer, and is used by the compensation circuit to control the signal produced by the pressure transducer, compensating for the characteristic sensitivity of the device. In a second embodiment, the disposable cable includes an offset resistor (250), and the compensation system uses a charge balance modulator 9260) to produce a pulse width modulated signal that is compensated for both the offset and characteristic sensitivity of the pressure transducer.

52693112, Dec 14, 1993

May 11, 1992

7/881726

Richard A. Kirchner - Santa Clara CA
Timothy A. Shotter - Sunnyvale CA
Robert W. Beard - late of Placerville CA

Abbott Laboratories - Abbott Park IL

A61B 500

128672

Disclosed is a method of compensating any of a plurality of different pressure transducers for their characteristic pressure sensitivity, zero pressure offset, and self-heating error. The method comprises selecting a gain resistor that adjusts the gain of an output signal of the pressure transducer in use so that the pressure transducer appears as an ideal pressure transducer to a pressure monitor. The self-heating error is compensated by measuring an initial bridge voltage that drives the transducer and an initial output signal of the pressure transducer when the transducer is first energized. After a period of time a second bridge voltage and a second output signal are determined. The self-heating error is determined as a function of the difference between the initial and second values. The zero pressure offset is compensated by determining the output signal of the pressure transducer at zero gauge pressure after the pressure has been compensated for the self-heating error.