Claims
- 1. Method of temperature-compensating a sensor having, at any given temperature within a range of temperature suitable for use of the sensor, a straight characteristic line giving the relation between sensor output (7) and a physical property variable (P) measured by said sensor, said characteristic line having a slope (k) which has a first temperature coefficient (TK.sub.k) and defining, for a predetermined value of said physical variable, a reference value (U.sub.off) of sensor output which reference value has a second temperature coefficient (TK.sub.off), said method depending upon the discovery that the respective characteristic lines of said sensor for various temperatures commonly cross in a point (14), said method comprising the steps of:
- determining, from preliminary measurements of known magnitudes at not less than two different sensor temperatures the coordinates (U.sub.0, P.sub.0) of said point (14) representing a value of said physical variable for which the sensor output does not vary with temperature, and providing said coordinates and also said first and second temperature coefficients (TK.sub.k,TK.sub.off) as sensor constants to a microcomputer (20);
- calculating the slope (k.sub.0) of the sensor characteristic at a reference temperature (T.sub.0) from said preliminary measurements and providing its value as a sensor constant to said microcomputer;
- continually measuring the sensor temperature (T) and furnishing its value as an operating variable to said microcomputer;
- continually furnishing said sensor signal (U.sub.(P,T)) to said microcomputer for derivation of said physical variable (P.sub.(T));
- deriving a value of said physical variable (P.sub.(T)) from said sensor signal (U.sub.(P,T) and from the determined sensor temperature (T) by computation in said microprocessor in accordance with the relation:
- P.sub.(T) =P.sub.0 +(U.sub.(P,T) -U.sub.0)/k.sub.0 (1+TK.sub.k .DELTA.T)
- in which
- P.sub.0 and U.sub.0 are said coordinates of said point,
- U.sub.(P,T) is the sensor signal,
- k.sub.0 is said slope for the sensor characteristic at said reference temperature,
- .DELTA.T is the difference (T-T.sub.0) between the determined sensor temperature (T) and the said reference temperature T.sub.0 and
- TK.sub.k is the temperature coefficient of the sensor characteristic slope at said sensor temperature.
- 2. Method according to claim 1, in which the step of calculating the slope (k.sub.0) of the sensor characteristic at said reference temperature (T.sub.0) is performed by supplying data of said preliminary measurements to said computer for calculation in said computer.
- 3. Method according to claim 1, in which the step of providing said coordinates (U.sub.0, P.sub.0) of said point (14) to said microcomputer also includes the storing, in signal storage means (22) available to said microcomputer (20), digital signals (32) corresponding to said coordinates.
- 4. Method according to claim 1, in which the provision of said coordinates (U.sub.0,P.sub.0) of said point (14) is performed by setting first and second potentiometers (29, 30) to provide electrical outputs respectively representative of said coordinates and utilizing analog-to-digital converter means (23) for converting said potentiometer outputs into digital signals for use by said microcomputer (20).
- 5. Method according to claim 1, in which the provision of said coordinates (U.sub.0,P.sub.0) of said point (14) to said microcomputer (20) is performed by setting digital signal sources to produce digital signals corresponding to said coordinates and to supply them directly to said microcomputer.
Priority Claims (1)
Number |
Date |
Country |
Kind |
3212611 |
Apr 1982 |
DEX |
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Parent Case Info
This application is a continuation of application Ser. No. 478,688, filed Mar. 25, 1983, now abandoned.
US Referenced Citations (10)
Foreign Referenced Citations (1)
Number |
Date |
Country |
0140055 |
Dec 1978 |
JPX |
Continuations (1)
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Number |
Date |
Country |
Parent |
478688 |
Mar 1983 |
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