Condensation sensor

• US 20060203879A1
• Filed: 03/13/2006
• Published: 09/14/2006
• Est. Priority Date: 09/11/2003
• Status: Active Grant

• Current Assignee: PREH GmbH (Ningbo Junsheng Investment Group Co., Ltd.)
• Original Assignee: PREH GmbH (Ningbo Junsheng Investment Group Co., Ltd.)
• Inventors: Ruttiger, Anton, Peschel, Markus
• Granted Patent: US 7,416,331 B2
• Time in Patent Office: Days
• US Class Current: 374/142
• CPC Class Codes: B60H 1/00785 by the detection of humidity or frost

Abstract

A measuring device for detecting a humidity and temperature of a window surface including 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, and a signal converting and linking unit placed between the moisture and temperature sensors and the evaluation unit. Further, 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 an oscillator included in the signal and converting unit is changed.

Claims

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; and

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

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 an oscillator included in the signal and converting unit is changed.

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

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

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

5. The measuring device according to claim 2, wherein the oscillator and the frequency divider are placed on a common circuit board.

6. The measuring device according to claim 5, further comprising an interface to a bus system placed on the circuit board.

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

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

9. The measuring device according to claim 8, 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.

10. 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.

11. The method 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. The method according to claim 10, wherein the pulse length is changed when the detected moisture or temperature changes.

13. The method according to claim 10, wherein the temperature sensor comprises a resistor having a negative temperature coefficient.

14. The method according to claim 10, wherein the moisture sensor comprises a capacitor with a moisture-sensitive intermediate layer.

15. The method according to claim 10, wherein the frequency generated by the oscillator is divided in a downstream frequency divider.