Calibration in a Laboratory Reference Method

• US 20090145195A1
• Filed: 12/13/2006
• Published: 06/11/2009
• Est. Priority Date: 12/23/2005
• Status: Active Grant

• Current Assignee: Endress+Hauser GmbH+Co (ENDRESS)
• Original Assignee: Endress+Hauser GmbH+Co (ENDRESS)
• Inventors: Husges, Ralf, Roth, Philipp, Buttmann, Marc
• Granted Patent: US 7,979,227 B2
• Time in Patent Office: Days
• US Class Current: 73/1.30
• CPC Class Codes: G01D 18/008 with calibration coefficients stored in memory
• CPC Class Codes: G01N 21/274 Calibration, base line adjustment, drift correction

Abstract

A method for calibrating a measuring device monitoring at least one measured variable of a measured medium by means of at least a first sensor, wherein the signal of the first sensor is mapped to a measured value on the basis of a mapping specification, and wherein the method includes the following steps: a current measured value of the measuring device is recorded as current calibration measured value; a laboratory reference sample of the measured medium with the properties of the calibrated measured value at the point in time of the recording is supplied to a laboratory reference measuring device; the actual value of the measured variable is ascertained with the laboratory reference measuring device on the basis of the laboratory reference sample and made available and recorded as current laboratory reference measured value; and, on the basis of the current calibration measured value, as well as the current laboratory reference measured value, the mapping specification is updated, characterized in that at least one earlier value pair of a calibration measured value and an associated laboratory reference measured value ascertained in an earlier calibration is taken into consideration for the updating of the mapping specification.

Claims

1-7. -7. (canceled)

8. A method for calibrating a measuring device monitoring a measured variable of a measured medium on the basis of at least a first sensor, wherein a signal of the first sensor is mapped to a measured value on the basis of a mapping specification, comprising the steps of:

recording at a point in time a current measured value of the measuring device as a current calibration measured value;

supplying to a laboratory reference measuring device a laboratory reference sample of the measured medium having properties of the measured medium which are the same as those at the point in time of the recording of the calibration measured value;

ascertaining with the laboratory reference measuring device an actual value of the measured variable on the basis of the laboratory reference sample and making available and storing the actual value as a current laboratory reference measured value;

updating the mapping specification based on the current calibration measured value as well as the current laboratory reference measured value; and

at least one, earlier value pair of a calibration measured value and an associated laboratory reference measured value, ascertained in an earlier calibration, is taken into consideration for updating the mapping specification.

9. The method as claimed in claim 8, wherein:

a plurality of earlier value pairs of calibration measured values and laboratory reference measured values are taken into consideration for updating the mapping specification.

10. The method as claimed in claim 8, wherein:

the age of the value pairs is taken into consideration in selecting weighting factors for updating the mapping specification, and older value pairs have lesser weight than younger value pairs.

11. The method as claimed in claim 8, wherein:

calibration is performed periodically.

12. The method as claimed in claim 8, wherein:

calibration is performed under event control.

14. The measuring device as claimed in claim 15, wherein:

said measuring device is a turbidity measuring device for monitoring drinking water.