Humidifier and a method of monitoring the water level in the humidifier

1. A humidifier comprising:

a water level monitoring unit which comprises:

a temperature sensor for detecting the temperature at an air outlet and generating temperature signals indicating the temperature thereof at a predetermined frequency; and

a processor means for determining the water level in the humidifier according to the temperature signals.

2. The humidifier apparatus according to claim 1 , wherein the temperature sensor is arranged to sample the temperature signals at a first predetermined frequency during a first operational time period; and sample the temperature signals at a second predetermined frequency during a second operational time period.

3. The humidifier apparatus according to claim 1 , wherein the first predetermined sampling frequency is once every 7 seconds and the first operational time period is from turn-on till the humidifier has operated for five minutes.

4. The humidifier apparatus according to claim 1 , wherein the second predetermined sampling frequency is once every 30 seconds and the second operational time period starts after the humidifier has operated for five minutes.

5. The humidifier apparatus according to claim 1 , wherein the processor means is arranged to:

determine the inclination of the temperature change from 5 consecutive samples, and determine whether the temperature drop within 45 seconds is in the range of 0.15-0.45° C., in the first time period;

and if so, determine that there is a substantial level of water in the humidifier, or if not, determine that there is not a substantial level of water in the humidifier.

6. The humidifier apparatus according to claim 1 , wherein the processor means is arranged to

determine the inclination of the temperature change from 10 consecutive samples, and determine whether the temperature rise within 30 seconds is in the range of 0.05-0.35° C., in the second time period;

and if so, identify that there is no substantial level of water in the humidifier, or if not, identify that there is a substantial level of water in the humidifier.

7. The humidifier apparatus according to claim 1 , wherein the water level monitoring unit further comprises an alert unit, which issues a signal indicating that the humidifier needs to be filled with water, following an instruction from the processor means upon determining that there is no substantial level of water in the humidifier.

8. The humidifier apparatus according to claim 1 , wherein the processor means is arranged to issue an instruction to turn down the humidifier apparatus upon determining that there is no substantial level of water in the humidifier.

9. A water level monitoring unit, used in a humidifier apparatus as claimed in claim 1 , comprising:

a temperature sensor arranged at or near the air outlet of the humidifier apparatus, for detecting the temperature at the air outlet and generating a temperature signal indicating the temperature thereof at a predetermined frequency; and

a processor means for determining the inclination of the temperature change over time and, consequently, whether there is a substantial level of water in the humidifier, based on the sampled signals.

10. A method of monitoring the water level in a humidifier, the method comprising the steps of:

a) detecting the temperature at the air outlet of the humidifier and generating temperature signals indicating the temperature thereof at a predetermined frequency; and

b) determining the water level in the humidifier according to the processor, based on the generated temperature signals.

11. The method according to claim 10 , wherein step a) further comprises:

generating temperature signals at a first pre-determined frequency during a first operational time period, the first operational time period being a predetermined time period from turn-on of the humidifier; and

step b) further comprises:

determining whether a decreased temperature trend is shown by consecutive temperature signals generated during the first operational time period, in which case the water level is determined as high; otherwise, the water level is determined as low.

12. The method according to claim 11 , wherein step a) further comprises:

generating temperature signals at a second pre-determined frequency during a second operational time period, the second operational time period being after the first operational time period, and the second pre-determined frequency is lower than the first pre-determined frequency; and

Step b) further comprises:

determining whether an increased temperature trend is shown by consecutive temperature signals generated during the second operational time period, in which case the water level is determined as low.

13. The method according to claim 10 , wherein the method further comprises:

if the water level of the humidifier is determined as low, indicating that the humidifier needs to be filled with water and/or turning down the humidifier.