Air purifier including air filter life-time indicator and method for determining the life-time of an air filter

1. An air purifier, comprising:

an air inlet;

an air outlet;

a filter for removing gas pollutants or particles from air propagating from the air inlet to the air outlet;

a first sensor positioned for determining a water molecule adsorption level of the filter; and

a processor configured to determine a life-time of the filter based on the water molecule adsorption level of the filter measured by the first sensor.

2. The air purifier according to claim 1 , wherein the first sensor is a relative humidity sensor positioned for measuring a relative humidity of air filtered by the filter, and wherein the processor is configured to determine the life-time of the filter based on the relative humidity value measured by the first sensor.

3. The air purifier according to claim 2 , further comprising a memory, wherein the processor is configured to store a plurality of relative humidity values measured by the first sensor in the memory and relate changing characteristics of the plurality of relative humidity values to the life-time of the filter.

4. The air purifier according to claim 2 , further comprising a memory, wherein the processor is configured to store a plurality of relative humidity datasets measured by the first sensor in the memory, each dataset comprising different relative humidity values of filtered air for a relative humidity value of ambient air, and wherein determining the life-time of the filter is based on the plurality of relative humidity datasets.

5. The air purifier according to claim 2 , further comprising a second sensor positioned for measuring a relative humidity of ambient air, and wherein the processor is further configured to determine the life-time of the filter by comparing the relative humidity of ambient air measured by the second sensor with the relative humidity value measured by the first sensor.

6. The air purifier according to claim 5 , further comprising a memory, wherein the processor is configured to store a plurality of relative humidity datasets measured by the first sensor and the second sensor in the memory, each dataset comprising different relative humidity values of filtered air for a relative humidity value of ambient air, and wherein determining the life-time of the air filter is based on the plurality of relative humidity datasets.

7. The air purifier according to claim 5 , wherein the first sensor is positioned on one side of the filter, and wherein the second sensor is positioned on an other side of the filter.

8. The air purifier according to claim 7 , wherein the first sensor is positioned at the air outlet, and wherein the second sensor is positioned at the air inlet.

9. The air purifier according to claim 1 , wherein the filter is a removable filter.

10. The air purifier according to claim 1 , wherein the air purifier further comprising an indicator configured to signal the life-time of the filter to a user.

11. The air purifier according to claim 1 , wherein the indicator is a sound alarm or a light alarm.

12. The air purifier according to claim 1 , wherein the air purifier further comprising a detector for detecting a type of the filter.

13. A method for determining a life-time of a filter for removing gas pollutants or particles from air, the method comprising:

providing the filter for removing the gas pollutants or particles from air;

generating an air flow through the filter thereby filtering air;

determining, by using a sensor, a water molecule adsorption level of the filter; and

determining the life-time of the filter based on the determined water molecule adsorption level of the filter.

14. The method according to claim 13 , wherein determining the water molecule adsorption level of the filter comprises measuring a relative humidity of filtered air; and wherein determining the life-time of the filter is based on the measured relative humidity values of filtered air.

15. The method according to claim 14 , wherein measuring the relative humidity of filtered air is performed multiple times,

wherein the plurality of measured relative humidity values of filtered air are stored, and

wherein determining the life-time of the filter comprises relating changing characteristics of the plurality of relative humidity values to the life-time of the filter.

16. The method according to claim 14 , further comprising measuring a relative humidity of ambient air, and wherein determining the life-time of the filter is further based on the measured relative humidity values of ambient air.

17. The method according to claim 16 , wherein the measuring of the relative humidity of filtered air and the measuring of the relative humidity of ambient air is performed multiple times,

wherein the plurality of measured relative humidity values of the filtered and ambient air are stored as a plurality of relative humidity datasets, each dataset comprising different relative humidity values of the filtered air for a particular relative humidity value of the ambient air, and

wherein determining the life-time of the air filter is based on the plurality of datasets.

18. The method according claim 16 , wherein measuring the relative humidity of ambient air is performed before generating the air flow.

19. The air purifier according to claim 12 , wherein the type of the filter is used to select a set of pre-determined water molecule adsorption levels for the detected type of the filter.

20. The air purifier according to claim 19 , wherein a pre-determined water molecule adsorption level from the set of pre-determined water molecule adsorption levels is used to determine a current lifetime stage of the filter.