Method of controlling a windshield wiper system

• US 5,276,389 A
• Filed: 12/10/1992
• Issued: 01/04/1994
• Est. Priority Date: 12/14/1991
• Status: Expired due to Term

• Current Assignee: Leopold Kostal GmbH & Company KG
• Original Assignee: Leopold Kostal GmbH & Company KG
• Inventors: Levers, Juergen
• Primary Examiner(s): Ro, Bentsu
• Application Number:
  US07/988,769
• Time in Patent Office: 390 Days
• Field of Search: 318/443, 318/444, 318/480, 318/483, 318/DIG. 2, 15/250.12, 15/250.13, 15/250.17, 388/907.5, 388/916
• US Class Current: 318/444
• CPC Class Codes: B60S 1/0818 including control systems responsive to external conditions, e.g. by detection of moisture, dirt or the like
• CPC Class Codes: B60S 1/0833 Optical rain sensor
• CPC Class Codes: G01V 8/12 using one transmitter and one receiver
• CPC Class Codes: Y10S 318/02 Windshield wiper controls
• CPC Class Codes: Y10S 388/916 Threshold circuit

Abstract

A method for controlling a vehicular windshield wiping system, the wiping system being controlled in response to recognition of a particular rain pattern, and being capable of distinguishing between the presence of moisture and dirt on the windshield. The wiping system is also controlled according to a plurality of operating thresholds established to ensure smooth operation of the wiping system during varying conditions, and is controlled according an amplification autoranging strategy to ensure the wiping system functions properly independent of certain conditions, such as the type of windshield on the vehicle. The wiping system includes at least one wiper blade, and a sensor mounted to the windshield for monitoring a portion of the windshield. The sensor generates a signal having a value which varies as both moisture and dirt collect on the monitored portion.

Claims

1. A method of controlling a vehicular windshield wiping system, the wiping system including a sensor mounted to the windshield for monitoring a portion of the windshield and generating a sensor signal, the method comprising the steps of:

detecting the presence of at least one falling edge in the sensor signal, the at least one falling edge indicating the presence of moisture on the monitored portion of the windshield;

identifying the shape of the at least one falling edge, the wiping system detecting at least one rain pattern based on the shape and number of falling edges in the sensor signal during a predetermined period of time; and

controlling the windshield wiping system based on the identified rain pattern.

2. The method of claim 1 wherein the step of identifying the shape further comprises the step of identifying hard falling edges, each hard falling edge representing a single drop of moisture on the monitored portion of the windshield.

3. The method of claim 2 wherein the step of identifying the shape further comprises the step of identifying soft falling edges, a soft falling edge indicating a drizzle-like moisture pattern on the monitored portion of the windshield.

4. The method of claim 3 wherein the step of controlling the windshield wiping system further comprises the step of determining a delay period between consecutive wipes of the windshield if the number of hard falling edges substantially exceeds the number of soft falling edges during the predetermined period of time.

5. The method of claim 4 further comprising the step of operating the wiping system in an intermittent mode wherein there is a variable delay period between consecutive wipes of the windshield.

6. A method of controlling a vehicular windshield wiping system including at least one wiper blade, and a sensor mounted to the windshield for monitoring a portion of the windshield, the sensor generating a signal having a value which varies as moisture or dirt or both collect on the monitored portion, the wiping system being activated when the sensor value crosses a predetermined switch-on threshold and deactivated when the sensor value is above a predetermined switch off threshold, the method comprising the steps of:

determining a first sensor value when the monitored portion is substantially free of moisture, the first sensor value being less than a maximum possible sensor value due to the presence of dirt on the monitored portion, thereby allowing the windshield wiping system to distinguish between the presence of moisture and dirt on the monitored portion based on the first sensor value;

modifying the predetermined switch-on and switch-off thresholds based on the first sensor value; and

controlling the windshield wiping system based on the modified thresholds, thereby insuring the wiping system is activated due only to the presence of moisture on the monitored portion.

7. The method of claim 6 further comprising the step of activating the wiping system for at least one wipe cycle when the sensor value drops below the predetermined switch-on threshold, the at least one wiper blade leaving a resting position and wiping the windshield, passing over the monitored portion of the windshield at least once.

8. The method of claim 7 wherein the first sensor value is determined after the at least one wiper blade passes over the monitored portion of the windshield for the last time during the wipe cycle, the monitored portion being substantially dry after the blade passes.

9. A method of controlling a vehicular windshield wiping system including at least one wiper blade, and a sensor mounted to the windshield for monitoring a portion of the windshield, the sensor generating a signal having a value which varies as moisture or dirt or both collect on the monitored portion, the wiping system being activated when the sensor value crosses a predetermined switch-on threshold, and deactivated when the sensor value is above a predetermined switch-off threshold, the method comprising the steps of:

activating the wiping system for at least one wipe cycle when the sensor value drops below the predetermined switch-on threshold, the at least one wiper blade leaving a resting position and wiping the windshield, passing over the monitored portion of the windshield at least once;

determining a first sensor value after the at least one wiper blade passes over the monitored portion of the windshield for the last time during the wipe cycle, the monitored portion being substantially free of moisture, the first sensor value being less than a maximum possible sensor value due to the presence of dirt on the monitored portion so as to allow the windshield wiping system to distinguish between the presence of moisture and dirt on the monitored portion;

modifying the predetermined switch-on and switch-off thresholds based on the first sensor value; and

controlling the windshield wiping system based on the modified thresholds, thereby insuring the wiping system is activated due only to the presence of moisture on the monitored portion.

10. A method of controlling a vehicular windshield wiping system, the wiping system including at least one windshield wiper and a sensor mounted to the windshield for monitoring a portion of the windshield wiped by the wiper during each wipe cycle, the sensor generating a sensor signal having a value which varies as a coating collects on the monitored portion of the windshield, the method comprising the steps of:

defining a connection threshold based on the sensor signal, for starting operation of the windshield wiping system;

defining a first disconnection threshold based on the sensor signal, for ceasing operation of the windshield wiping system in a first mode of operation; and

defining a second disconnection threshold based on the sensor signal, for ceasing operation of the windshield wiping system in a second mode of operation.

11. The method of claim 10 wherein the first mode of operation is an intermittent mode of operation in which successive wipes of the wiper across the windshield are separated by a predetermined time delay, and wherein the second mode of operation is a continuous mode of operation in which successive wipes of the wiper across the windshield are not separated by a predetermined time delay.

13. The method of claim 11 wherein the disconnection threshold for the continuous wiping mode has a value which exceeds the value of the disconnection threshold for the intermittent wiping mode.

14. The method of claim 11 further comprising the step of maintaining operation of the windshield wiping system after operation in the continuous mode even if the sensor value exceeds the disconnection threshold for the continuous mode of operation, such that the wiping system operates for at least one additional wiping cycle.

15. The method of claim 10 further comprising the step of defining an interference threshold based on the sensor signal, the interference threshold having a predetermined value for indicating the presence of a coating on the windshield with substantial certainty.

16. The method of claim 15 wherein the connection threshold is a variable quantity, and further comprising the step of incrementing the connection threshold in predetermined intervals from an original value when the sensor signal has a value which falls below the interference threshold.

17. The method of claim 16 wherein the step of incrementing includes incrementing the connection threshold at a rate which varies based on the period of time during which the sensor signal remains below the interference threshold but above the connection threshold.

18. The method of claim 17 further comprising the step of decrementing the connection threshold to the original value when the sensor signal, within a specific period of time after falling below the interference threshold, again exceeds the interference threshold.

19. The method of claim 10 wherein the connection threshold has a value of about 93% of the sensor signal value associated with an optimally clean windshield.

20. The method of claim 10 wherein the first disconnection threshold has a value of about 95% of the sensor signal value associated with an optimally clean windshield.

21. The method of claim 10 wherein the second disconnection threshold has a value of about 97% of the sensor signal value associated with an optimally clean windshield.

22. The method of claim 15 wherein the interference threshold has value of about 98% of the sensor signal value associated with an optimally clean windshield.

12. The method of claim wherein the disconnection threshold for the intermittent wiping mode has a value which exceeds the value of the connection threshold.

23. A method of controlling a vehicular windshield wiping system including a motor, at least one windshield wiper and an optoelectronic sensor mounted to the windshield for monitoring a portion of the windshield wiped by the wiper during each wipe cycle, the sensor including infrared beam transmitters for emitting beams and infrared beam receivers for receiving the emitted beams, the emitted beams being modified based on the coating on the windshield, the sensor generating a signal having a value which varies as a coating collects on the monitored portion of the windshield, the method comprising the steps of:

establishing a data window having a first plurality of values based on the sensor signal;

establishing a measurement range within the data window, the measurement range having a second plurality of values defined by an upper threshold and a lower threshold; and

modifying the amplification of the beams emitted by the beam transmitters if the sensor signal has a value which is outside of the measurement range.

24. The method of claim 23 wherein the step of modifying includes incrementing the amplification of the emitted beams if the sensor signal has a value which is less than the lower threshold.

25. The method of claim 23 wherein the step of modifying includes decrementing the amplification of the emitted beams if the sensor signal has a value which is exceeds the upper threshold.

26. The method of claim 23 wherein the step of modifying includes amplifying the beams received by the beam receivers.

27. The method of claim 23 wherein the step of modifying is completed when the motor is deactivated.

28. A method of controlling a vehicular windshield wiping system including a motor, at least one windshield wiper and an optoelectronic sensor mounted to the windshield for monitoring a portion of the windshield wiped by the wiper during each wipe cycle, the sensor including infrared beam transmitters for emitting beams and infrared beam receivers for receiving the emitted beams, the emitted beams being modified based on the coating on the windshield, the sensor generating a sensor signal having a value which varies as a coating collects on the monitored portion of the windshield, the method comprising the steps of:

establishing a data window based on the sensor signal, the data window having a first plurality of values defined by an upper boundary and a lower boundary; and

modifying the amplification of the beams emitted by the beam transmitters if the sensor signal has a value which is outside of the data window.

29. The method of claim 28 wherein the step of modifying includes incrementing the amplification of the emitted beams if the sensor signal has a value which is less than the lower boundary.

30. The method of claim 28 wherein the step of modifying includes decrementing the amplification of the emitted beams if the sensor signal has a value which is exceeds the upper boundary.

31. The method of claim 28 wherein the step of modifying includes amplifying the beams received by the beam receivers.

32. The method of claim 28 wherein the step of modifying is completed when the motor is activated.

33. A method of controlling a vehicular windshield wiping system including a motor, at least one windshield wiper and an optoelectronic sensor mounted to the windshield for monitoring a portion of the windshield wiped by the wiper during each wipe cycle, the sensor including infrared beam transmitters for emitting beams and infrared beam receivers for receiving the emitted beams, the emitted beams being modified based on the coating on the windshield, the sensor generating a sensor signal having a value which varies as a coating collects on the monitored portion of the windshield, the method comprising the steps of:

establishing a data window based on the sensor signal, the data window having a first plurality of values defined by an upper boundary and a lower boundary;

establishing a measurement range within the data window, the measurement range having a second plurality of values defined by an upper threshold and a lower threshold;

modifying the amplification of the beams emitted by the beam transmitters if the sensor signal has a value which is outside of the measurement range when the motor is deactivated; and

modifying the amplification of the beams emitted by the beam transmitters if the sensor signal has a value which is outside of the data window when the motor is activated.

34. The method of claim 33 wherein the step of modifying the amplification of the beams emitted by the beam transmitters if the sensor signal has a value which is outside of the measurement range when the motor is deactivated includes incrementing the amplification of the emitted beams if the sensor signal has a value which is less than the lower threshold.

35. The method of claim 33 wherein the step of modifying the amplification of the beams emitted by the beam transmitters if the sensor signal has a value which is outside of the measurement range when the motor is deactivated includes decrementing the amplification of the emitted beams if the sensor signal has a value which is exceeds the upper threshold.

36. The method of claim 33 wherein the step of modifying the amplification of the beams emitted by the beam transmitters if the sensor signal has a value which is outside of the data window when the motor is activated includes incrementing the amplification of the emitted beams if the sensor signal has a value which is less than the lower boundary.

37. The method of claim 33 wherein the step of modifying the amplification of the beams emitted by the beam transmitters if the sensor signal has a value which is outside of the data window when the motor is activated includes decrementing the amplification of the emitted beams if the sensor signal has a value which is exceeds the upper boundary.