Condensation sensor

• US 7,331,531 B2
• Filed: 03/13/2006
• Issued: 02/19/2008
• 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: Nauth, Ju, Ruttiger, Anton
• Primary Examiner(s): Jiang; Chen Wen
• Application Number:
  US11/373,249
• Publication Number:
  US 20060202044A1
• Time in Patent Office: 708 Days
• Field of Search: 73/290.1, 73/290.4, 73/290.5, 733/350.2, 733/350.3, 733/350.4, 733/350.5, 733/350.7, 621/50, 621/761, 621/762, 236/44.C, 324/689, 374/27, 374/28, 374/16, 374/21, 374/142, 374/183
• US Class Current: 236/44.00C
• 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 surface of a glass pane facing an interior of a vehicle. The measuring device includes at least one humidity sensor and at least one temperature sensor jointly arranged on the surface of the glass pane, an evaluation unit connected downstream of the humidity and temperature sensors, and a signal conversion and linking unit arranged between the humidity and temperature sensors and the evaluation unit. Further, the converting and linking unit generates a rectangular wave-shaped signal having at least two different impulse lengths, each impulse length being a measure of a detected humidity and temperature.

Claims

1. A measuring device for detecting a humidity and temperature of a surface of a glass pane facing an interior of a vehicle, comprising:

at least one humidity sensor and at least one temperature sensor jointly arranged on the surface of the glass pane;

an evaluation unit connected downstream of the humidity and temperature sensors; and

a signal converting and linking unit arranged between the humidity and temperature sensors and the evaluation unit.

2. The measuring device according to claim 1, wherein the evaluation unit evaluates the humidity and temperature sensors in successive turns.

3. The measuring device according to claim 1, further comprising:

an oscillator connected downstream of each sensor,

wherein the signal and converting unit includes a frequency divider and a changeover logic unit.

4. The measuring device according to claim 3, wherein the converting and linking unit generates a rectangular wave-shaped signal having at least two different impulse lengths, each impulse length being a measure of a detected humidity and temperature in the humidity and temperature sensors.

5. The measuring device according to claim 3, wherein the oscillators, the changeover logic unit, and the frequency divider are arranged on a mutual printed circuit board.

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

7. The measuring device according to claim 1, wherein the temperature sensor comprises a resistor equipped with a negative temperature coefficient.

8. The measuring device according to claim 1, wherein the humidity sensor comprises a condenser having a moisture-sensitive intermediate layer.

9. The measuring device according to claim 1, wherein the glass pane comprises a windshield of a motor vehicle.

10. A measuring device according to claim 1, wherein the converting and linking is configured to combine first and second signals from the at least one humidity sensor and the at least one temperature sensor into a composite signal having a rectangular wave form.

11. A method for detecting a measuring signal to determine a temperature and humidity of a surface of a glass pane facing a passenger compartment, said method comprising:

detecting the humidity of the surface of the glass pane using a humidity sensor;

detecting the temperature of the surface of the glass pane using a temperature sensor;

generating first and second signals respectively corresponding to the detected humidity and temperature using oscillators arranged downstream of the humidity and temperature sensors; and

converting and linking the first and second signals into a composite signal having a rectangular wave form.

12. The method according to claim 11, wherein temperature is detected by a negative coefficient temperature resistor.

13. The method according to claim 11, wherein a change in the temperature or the moisture on the surface of the pane generates an altered resistance value and an altered capacitance value, respectively, which is detected by the humidity and temperature sensors, and that as a consequence of the altered detected values, the generating step generates different frequencies represent the altered changes, and the converting and linking step generates an altered rectangular wave-shaped signal.

14. The method according to claim 11, wherein the glass pane comprises a windshield of a motor vehicle.

15. A measuring device, comprising:

at least one humidity sensor configured to detect a humidity of a surface of a glass panel and to output a corresponding humidity measuring signal;

at least one temperature sensor configured to detect a temperature of the surface of the glass pane and to output a corresponding temperature measuring signal;

a combination unit configured to combine the humidity and temperature measuring signals into a combined signal; and

an evaluation unit configured to evaluate the combined signal to determine a current temperature and humidity of the surface of the glass pane.

16. The measuring device according to claim 15, wherein the humidity and temperature sensors are affixed to the glass pane next to each other.

17. The measuring device according to claim 15, further comprising:

a first oscillator connected to the humidity sensor and configured to generate a first frequency indicative of the detected humidity; and

a second oscillator connected to the temperature sensor and configured to generate a second frequency indicative of a detected temperature.

18. The measuring device according to claim 17, wherein the first and second oscillators and the combination unit are arranged on a printed circuit board separate from the humidity and temperature sensors.

19. The measuring device according to claim 15, wherein the combination unit includes a frequency divider and a changeover logic unit to thereby produce a rectangular wave-shaped combined signal having pulse lengths indicative of the detected humidity and temperature on the glass pane.

20. The measuring device according to claim 15, wherein the temperature sensor comprises a resistor equipped with a negative temperature coefficient, and the humidity sensor comprises a condenser having a moisture-sensitive intermediate layer.

21. The measuring device according to claim 15, wherein the combination unit generates a rectangular wave-shaped signal having at least two different impulse lengths, each impulse length being a measure of the detected humidity and temperature, respectively.

22. The measuring device according to claim 15, wherein the glass pane comprises a windshield of a motor vehicle.