Condensation sensor

1. A measuring device for detecting a humidity and temperature of a window surface, comprising:

at least one moisture sensor and at least one temperature sensor placed on the window surface;

an evaluation unit connected downstream from the moisture and temperature sensors,

an oscillator functionally coupled to the at least one moisture sensor and the at least one temperature sensor, wherein the oscillator receives an input signal from the at least one moisture sensor and an input signal from the at least one temperature sensor; and

a signal converting and linking unit placed between the moisture and temperature sensors and the evaluation unit, wherein the signal converting and linking unit comprises the oscillator;

wherein when the temperature sensor detects a change in a temperature of the window surface or the moisture sensor detects a change in a moisture of the window surface, a frequency of the oscillator included in the signal and converting unit is changed.

2. The measuring device according to claim 1 , wherein the temperature sensor comprises a resistor having a negative temperature coefficient.

3. The measuring device according to claim 1 , wherein the moisture sensor comprises a capacitor with a moisture-sensitive intermediate layer.

4. The measuring device according to claim 1 , wherein the window comprises a windshield of a vehicle.

5. The measuring device according to claim 1 , wherein the signal converting unit outputs a single signal using the oscillator, wherein the single signal represents both the measured temperature and moisture.

6. The measuring device according to claim 1 , wherein the signal converting unit merges the input signal from the at least one moisture sensor and the input signal from the at least one temperature sensor into a single signal, and

wherein the signal converting unit outputs the single signal to the evaluation unit.

7. The measuring device according to claim 1 , wherein the signal and converting unit further includes a frequency divider connected downstream from the oscillator.

8. The measuring device according to claim 7 , wherein the oscillator and the frequency divider are placed on a common circuit board.

9. The measuring device according to claim 8 , further comprising an interface to a bus system placed on the circuit board.

10. A measuring device for detecting a humidity and temperature of a window surface, comprising:

at least one moisture sensor and at least one temperature sensor placed on the window surface;

an evaluation unit connected downstream from the moisture and temperature sensors,

a signal converting and linking unit placed between the moisture and temperature sensors and the evaluation unit, wherein the signal converting and linking unit comprises

an oscillator functionally coupled to the at least one moisture sensor and the at least one temperature sensor; and

wherein when the temperature sensor detects a change in a temperature of the window surface or the moisture sensor detects a change in a moisture of the window surface, a frequency of the oscillator included in the signal and converting unit is changed and the signal converting and linking unit outputs a single signal using the oscillator, said single signal representing both the measured temperature and moisture.

11. The measuring device according to claim 10 , wherein the single signal comprises a rectangular-wave shaped signal in which a pulse length is a direct measure of a tendency for condensation on the window surface.

12. A method for detecting a measuring signal to determine a temperature and moisture of a window surface, said method comprising:

detecting the moisture of the window surface using a moisture sensor

detecting the temperature of the window surface using a temperature sensor; and

generating a single signal respectively corresponding to the detected humidity and temperature using an oscillator arranged downstream from the moisture and temperature sensors,

wherein when the temperature sensor detects a change in a temperature of the window surface or the moisture sensor detects a change in a moisture of the window surface, a frequency of the oscillator is changed, further wherein the oscillator is linked to the temperature sensor to shorten the reaction time of the moisture sensor.

13. The method according to claim 12 , wherein the temperature sensor comprises a resistor having a negative temperature coefficient.

14. The method according to claim 12 , wherein the moisture sensor comprises a capacitor with a moisture-sensitive intermediate layer.

15. The method according to claim 12 , wherein the frequency generated by the oscillator is divided in a downstream frequency divider.

16. A method for detecting a measuring signal to determine a temperature and moisture of a window surface, said method comprising:

detecting the moisture of the window surface using a moisture sensor;

detecting the temperature of the window surface using a temperature sensor; and

generating a single signal respectively corresponding to the detected humidity and temperature using an oscillator arranged downstream from the moisture and temperature sensors,

wherein when the temperature sensor detects a change in a temperature of the window surface or the moisture sensor detects a change in a moisture of the window surface, a frequency of the oscillator is changed, further wherein the oscillator is linked to the temperature sensor to shorten the reaction time of the moisture sensor and the single signal comprises a rectangular-wave shaped signal in which a pulse length is a direct measure of a tendency for condensation on the window surface.

17. The method according to claim 16 , wherein the pulse length is changed when the detected moisture or temperature changes.