Multi-function light sensor for vehicle

• US 6,084,519 A
• Filed: 05/13/1997
• Issued: 07/04/2000
• Est. Priority Date: 05/07/1993
• Status: Expired due to Fees

• Current Assignee: Control Devices Incorporated (Sensata Technologies Holding Plc)
• Original Assignee: Control Devices Incorporated (Sensata Technologies Holding Plc)
• Inventors: Pearson, Jonathan D., Hegyi, Dennis J., Coulling, Keith J.
• Primary Examiner(s): Lieu, Julie
• Application Number:
  US08/855,188
• Time in Patent Office: 1,148 Days
• Field of Search: 340/602, 340/604, 250/574, 250/575, 15/DIG. 15, 15/250.001, 15/250.12, 318/483, 318/DIG. 2
• US Class Current: 340/602
• 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 1/0822 characterized by the arrangement or type of detection means
• CPC Class Codes: B60S 1/0833 Optical rain sensor
• CPC Class Codes: B60S 1/0888 characterized by the attachment of the elements in a unit
• CPC Class Codes: Y10S 15/15 Moisture responsive
• CPC Class Codes: Y10S 318/02 Windshield wiper controls

Abstract

An apparatus and method for controlling the operation of the windshield wipers of a vehicle in response to the deposition of water on the exterior of the windshield; the operation of the air conditioning system in response to the formation of water condensation on the interior of the windshield of the vehicle; and the operation of the ventilation system in response to the presence of smoke in the cabin of the vehicle.

Claims

1. An apparatus for detecting the presence of water droplets on a windshield of a vehicle, comprising:

a first sensor channel, comprising;

a first light source for illuminating a first portion of the windshield with first light rays; and

a first light sensor for detecting, and for producing a first output proportional to, at least a portion of the first light rays scattered by the water droplets on the windshield, wherein first light rays directly reflected by the windshield do not impinge upon the first light sensor;

a second sensor channel, comprising;

a second light source for illuminating a second portion of the windshield with second light rays; and

a second light sensor for detecting, and for producing a second output proportional to, at least a portion of the second light rays directly reflected by the windshield and at least a portion of the second light rays scattered by the water droplets on the windshield; and

a processor having inputs coupled to the first and second outputs, the processor producing a control signal indicative of whether the amount of water droplets on the windshield exceeds a predetermined threshold.

2. The apparatus of claim 1, wherein the first and second light sensors comprise a single light sensor operated with time division multiplexing.

3. The apparatus of claim 1, wherein the first and second light sources comprise infrared LEDs.

4. The apparatus of claim 1, further comprising:

a temperature sensor operative to sense a temperature of the first and second light sources; and

a drive circuit coupled to the temperature sensor and to the first and second light sources, wherein the drive circuit supplies a drive current to the first and second light sources and the drive current is reduced as the temperature of the first and second light sources increases.

5. The apparatus of claim 1, wherein no portion of the apparatus contacts the windshield.

6. The apparatus of claim 1, wherein the water droplets comprise rain on an exterior of the windshield and condensed water vapor fog on an interior of the windshield.

7. A method for detecting the presence of water droplets on a windshield of a vehicle, comprising the steps of:

a) illuminating a first portion of the windshield with first light rays;

b) sensing at least a portion of the first light rays scattered by the water droplets on the windshield;

c) illuminating a second portion of the windshield with second light rays;

d) sensing at least a portion of the second light rays directly reflected by the windshield and at least a portion of the second light rays scattered by the water droplets on the windshield; and

e) producing a control signal indicative of whether the amount of water droplets on the windshield exceeds a predetermined threshold based upon the sensed light of steps (b) and (d).

8. An apparatus for detecting the presence of water droplets on the windshield of a vehicle, comprising:

a first sensor channel operative to detect rain on an exterior of the windshield and produce a first output, the first sensor channel comprising;

a first light source for illuminating a first portion of the windshield with first light rays; and

a first light sensor for detecting, and for producing a first output proportional to, at least a portion of the first light rays scattered by the rain on the windshield, wherein first light rays directly reflected by the windshield do not impinge upon the first light sensor; and

a second sensor channel operative to detect condensed water vapor fog on an interior of the windshield and produce a second output, the second sensor channel comprising;

a second light source for illuminating a second portion of the windshield with second light rays; and

a second light sensor for detecting, and for producing a second output proportional to, at least a portion of the second light rays directly reflected by the windshield and at least a portion of the second light rays scattered by the fog on the windshield; and

a processor having inputs coupled to the first and second outputs, the processor operable to use the second output to correct the first output such that contributions to the first output caused by fog are substantially removed, wherein the processor is further operable to produce a control signal using the corrected first output, wherein the control signal is indicative of whether the amount of rain on the exterior of the windshield exceeds a predetermined threshold.

9. The apparatus of claim 8, wherein the first and second light sensors comprise a single light sensor operated with time division multiplexing.

10. The apparatus of claim 8, wherein the first and second light sources comprise infrared LEDs.

11. The apparatus of claim 8, further comprising:

a temperature sensor operative to sense a temperature of the first and second light sources; and

a drive circuit coupled to the temperature sensor and to the first and second light sources, wherein the drive circuit supplies a drive current to the first and second light sources and the drive current is reduced as the temperature of the first and second light sources increases.

12. The apparatus in claim 8, wherein no portion of the apparatus contacts the windshield.

13. An apparatus for detecting the presence of water droplets on the windshield of a vehicle, comprising:

at least one sensor operative to produce an output signal proportional to the amount of water droplets on the windshield, wherein no portion of the at least one sensor contacts the windshield, the at least one sensor comprising;

a first light source for illuminating a first portion of the windshield with first light rays; and

a first light sensor for detecting, and for producing a first output proportional to, at least a portion of the first light rays scattered by the water droplets on the windshield, wherein first light rays directly reflected by the windshield do not impinge upon the first light sensor;

a second sensor channel, comprising;

a second light source for illuminating a second potion of the windshield with second light rays; and

a second light sensor for detecting, and for producing a second output proportional to, at least a portion of the second light rays directly reflected by the windshield and at least a portion of the second light rays scattered by the water droplets on the windshield; and

a processor having inputs coupled to the first and second outputs, the processor producing a control signal indicative of whether the amount of water droplets on the windshield exceeds a predetermined threshold.

14. The apparatus of claim 13, wherein the first and second light sensors comprise a single light sensor operated with time division multiplexing.

15. The apparatus of claim 13, wherein the first and second light sources comprise infrared LEDs.

16. The apparatus of claim 13, further comprising:

a temperature sensor operative to sense a temperature of the first and second light sources; and

a drive circuit coupled to the temperature sensor and to the first and second light sources, wherein the drive circuit supplies a drive current to the first and second light sources and the drive current is reduced as the temperature of the first and second light sources increases.

17. The apparatus of claim 13, wherein the water droplets comprise rain on an exterior of the windshield and condensed water vapor fog on an interior of the windshield.

18. The apparatus of claim 13, wherein the at least one sensor comprises:

a first sensor channel operative to detect rain on an exterior of the windshield and produce a first output;

a second sensor channel operative to detect condensed water vapor fog on an interior of the windshield and produce a second output; and

a processor having inputs coupled to the first and second outputs, the processor operable to use the second output to correct the first output such that contributions to the first output caused by fog are substantially removed, wherein the processor is further operable to produce a control signal using the corrected first output, wherein the control signal is indicative of whether the amount of rain on the exterior of the windshield exceeds a predetermined threshold.

19. The apparatus of claim 18, wherein:

the first sensor channel comprises;

a first light source for illuminating a first portion of the windshield with first light rays; and

a first light sensor for detecting, and for producing a first output proportional to, at least a portion of the first light rays scattered by the rain on the windshield, wherein first light rays directly reflected by the windshield do not impinge upon the first light sensor; and

the second sensor channel comprises;

a second light source for illuminating a second portion of the windshield with second light rays; and

a second light sensor for detecting, and for producing a second output proportional to, at least a portion of the second light rays directly reflected by the windshield and at least a portion of the second light rays scattered by the fog on the windshield.

20. The apparatus of claim 19, wherein the first and second light sensors comprise a single light sensor operated with time division multiplexing.

21. The apparatus of claim 19, wherein the first and second light sources comprise infrared LEDs.

22. The apparatus of claim 19, further comprising:

a temperature sensor operative to sense a temperature of the first and second light sources; and

a drive circuit coupled to the temperature sensor and to the first and second light sources, wherein the drive circuit supplies a drive current to the first and second light sources and the drive current is reduced as the temperature of the first and second light sources increases.