Detection of contaminations on a sensing surface of a thermal sensor

A thermal sensor comprising:

• an active element configured to be supplied with power so as to cause a temperature change of the active element;
• at least two first temperature sensors arranged in different sectors of the sensing surface;
• at least two second temperature sensors arranged in different sectors of the sensing surface;
• and
• processing circuitry configured to carry out the following steps:
• causing power to be supplied to the active element;
• determining a multi-sector thermal parameter based on a combination of output signals of the at least two first temperature sensors and the at least two second temperature sensors, the multi-sector thermal parameter being indicative of a difference of a first temperature inhomogeneity parameter and a second temperature inhomogeneity parameter, the first temperature inhomogeneity parameter being indicative of a temperature inhomogeneity among the first temperature sensors, and the second temperature inhomogeneity parameter being indicative of a temperature inhomogeneity among the second temperature sensors;
• and
• determining a contamination signal that is indicative of a contamination on a surface of the thermal sensor based on the multi-sector thermal parameter.

A method of determining contaminations on a sensing surface of a thermal sensor, the thermal sensor comprising an active element comprised of a heater or cooler that is configured to be supplied with power so as to cause a temperature change of the active element, and at least one temperature sensor, the method comprising:

• causing a change of power supplied to the active element;
• at a plurality of times after said change of power, determining a thermal parameter based on output signals from the at least one temperature sensor to obtain a time-dependent transient behavior of the thermal parameter in response to the change of power;
• analyzing said time-dependent transient behavior of the thermal parameter in response to the change of power;
• based on the analysis of the time-dependent transient behavior of the thermal parameter, determining a contamination signal that is indicative of a contamination on a sensing surface of the thermal sensor.

A method of determining contaminations on a sensing surface of a thermal sensor, the thermal sensor comprising an active element configured to be supplied with power so as to cause a temperature change of the active element, at least two first temperature sensors arranged in different sectors of the sensing surface, and at least two second temperature sensors arranged in different sectors of the sensing surface, the method comprising:

• causing power to be supplied to the active element;
• determining a multi-sector thermal parameter based on a combination of output signals of the at least two first temperature sensors and the at least two second temperature sensors, the multi-sector thermal parameter being indicative of a difference of a first temperature inhomogeneity parameter and a second temperature inhomogeneity parameter, the first temperature inhomogeneity parameter being indicative of a temperature inhomogeneity among the first temperature sensors, and the second temperature inhomogeneity parameter being indicative of a temperature inhomogeneity among the second temperature sensors;
• and
• determining a contamination signal that is indicative of a contamination on a surface of the thermal sensor device based on the multi-sector thermal parameter.

A thermal sensor comprising:

• an active element configured to be supplied with power so as to cause a temperature change of the active element;
• at least two first temperature sensors arranged in different sectors of the sensing surface;
• at least two second temperature sensors arranged in different sectors of the sensing surface;
• and
• processing circuitry configured to carry out the following steps:
• causing power to be supplied to the active element;
• determining a multi-sector thermal parameter based on a combination of output signals of the at least two first temperature sensors and the at least two second temperature sensors, the multi-sector thermal parameter being indicative of a sum of a first temperature inhomogeneity parameter and a second temperature inhomogeneity parameter, the first temperature inhomogeneity parameter being indicative of a temperature inhomogeneity among the first temperature sensors, and the second temperature inhomogeneity parameter being indicative of a temperature inhomogeneity among the second temperature sensors;
• and
• determining a contamination signal that is indicative of a contamination on a surface of the thermal sensor based on the multi-sector thermal parameter.