METHOD AND APPARATUS FOR RAPID TEMPERATURE MEASUREMENT

• US 20100118913A1
• Filed: 04/28/2008
• Published: 05/13/2010
• Est. Priority Date: 05/03/2007
• Status: Active Grant

• Current Assignee: Renishaw PLC
• Original Assignee: Renishaw PLC
• Inventors: Courtois, Christian
• Granted Patent: US 8,517,602 B2
• Time in Patent Office: Days
• US Class Current: 374/102
• CPC Class Codes: G01K 15/00 Testing or calibrating of thermometers
• CPC Class Codes: G01K 7/42 Circuits effecting compensation of thermal inertia; Circuits for predicting the stationary value of a temperature

Abstract

A method of using a temperature sensor to determine the temperature of an object is described. The method comprises bringing the temperature sensor into thermal contact with the object to be measured. The temperature sensor is then used to acquire a plurality of temperature readings, the plurality of temperature readings being acquired prior to the temperature sensor reaching thermal equilibrium with the object. At least some of the plurality of temperature readings are then used to determine a pseudo-stable temperature at which the rate of change of temperature readings with time is less than a predetermined rate. The actual temperature of the object may then be predicted from the pseudo-stable temperature.

Claims

1. A method of using a temperature sensor to determine the temperature of an object, comprising;

(i) bringing the temperature sensor into thermal contact with the object to be measured;

(ii) using the temperature sensor to acquire a plurality of temperature readings, said plurality of temperature readings being acquired prior to the temperature sensor reaching thermal equilibrium with the object; and

(iii) using at least some of the plurality of temperature readings of step (ii) to determine a pseudo-stable temperature at which the rate of change of temperature readings with time is less than a predetermined rate.

2. A method according to claim 1 comprising (iv) predicting the temperature of the object using the pseudo-stable temperature determined in step (iii).

3. A method according to claim 2 comprising determining a start temperature, said start temperature being the temperature of the temperature sensor prior to thermal contact being established with the object.

4. A method according to claim 3 comprising determining a difference temperature between the pseudo-stable temperature and the start temperature.

5. A method according to claim 4 wherein step (iv) comprises predicting the temperature of the object by applying a correction to the pseudo-stable temperature, wherein the applied correction depends on the difference temperature.

6. A method according to claim 5 in which a look-up table is provided that comprises a plurality of predetermined corrections for a plurality of difference temperatures, wherein said applied correction is determined by reference to the look-up table.

7. A method according to claim 6 comprising taking at least two of said predetermined corrections and using an interpolation process to calculate the correction that is applied to the pseudo-stable temperature.

8. A method according to claim 6 comprising an initial calibration routine for determining said look-up table.

9. A method according to claim 1 wherein steps (ii) and (iii) are performed in parallel such that said temperature readings are monitored while being acquired to determine when the pseudo-stable temperature is reached.

10. A method according to claim 1 that is performed by a temperature sensor having a low thermal mass.

11. A method according to claim 1 wherein step (i) comprises using a machine to bring a temperature probe comprising the temperature sensor into contact with the object.

12. Temperature sensing apparatus comprising a temperature sensor for acquiring a series of temperature readings and a processor for monitoring said series of temperature readings, wherein the processor is arranged to monitor temperature readings acquired after the sensor contacts an object and to determine when a pseudo-stable temperature is reached at which the temperature readings vary with time but at less than a predetermined rate.

13. Apparatus according to claim 12 comprising a temperature measurement probe in which the temperature sensor is housed.

14. Apparatus according to claim 13 wherein the processor is also located within the measurement probe.

15. Apparatus according to claim 13 comprising an interface, wherein the processor is located in the interface and, in use, temperature readings are passed from the measurement probe to the interface.