Vehicle light assembly sensing moisture with light reflection

A vehicle light assembly including a housing, a light source, a lens disposed in front of the light source, a light sensor disposed in the housing outside of light output from the light source directed at the lens for sensing light reflected off the lens caused by moisture, and a heater disposed on the lens for reducing the moisture when moisture is sensed.

FIELD OF THE INVENTION

The present invention generally relates to vehicle lighting, and more particularly relates to vehicle lighting assemblies that sense and reduce moisture.

BACKGROUND OF THE INVENTION

Automotive vehicles are commonly equipped with various exterior lighting assemblies including vehicle headlights at the front of the vehicle and taillights at the rear of the vehicle. Vehicle exterior lighting assemblies typically include a light source disposed within a housing having an outer lens. Some assemblies experience moisture buildup on the inside of the lens. In addition, moisture in the form of snow and ice may accumulate on the outside of the lens in cold weather conditions. It is generally known to provide defogger elements on the lens to evaporate the moisture that may be present on the lens. It may be desirable to provide for an enhanced lighting assembly that senses moisture and reduces the moistures buildup on the lens.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, a vehicle light assembly is provided. The vehicle light assembly includes a housing, a light source, and a lens disposed in front of the light source. The vehicle light assembly also includes a sensor disposed in the housing for sensing light reflected from moisture on the lens, and a heater disposed on the lens and activated based on the sensed light for reducing the moisture.

Embodiments of the first aspect of the invention can include any one or a combination of the following features:the light assembly includes a controller for controlling the heater to heat the lens when moisture is detected with the sensor;the heater comprises an electric heater having a conductive circuit formed on the lens;the conductive circuit comprises a visually transparent conductive material;the sensor comprises a light sensor;the light source directs light output within a beam towards the lens and the sensor is disposed within the housing outside of the beam;the light assembly includes a light shield located between the light source and the sensor;the light assembly comprises a vehicle headlight on the front of the vehicle; andthe light assembly comprises a vehicle taillight on the rear of the vehicle.

According to another aspect of the present invention, a vehicle light assembly is provided. The vehicle light assembly includes a housing, a light source, and a lens disposed in front of the light source. The vehicle light assembly also includes a light sensor disposed in the housing outside of a beam of light output directed from the light source towards the lens for sensing light reflected from moisture on the lens, and a heater disposed on the lens for reducing the moisture.

Embodiments of the second aspect of the invention can include any one or a combination of the following features:the light assembly includes a controller for controlling the heater to heat the lens when moisture is detected with the sensor;the heater comprises an electric heater having a conductive circuit formed on the lens;the conductive circuit comprises a visually transparent conductive material;the light assembly includes a light shield located between the light source and the sensor;the light assembly comprises a vehicle headlight on the front of the vehicle; andthe light assembly comprises a vehicle taillight on the rear of the vehicle.

According to another aspect of the present invention, a vehicle headlight assembly is provided. The vehicle headlight assembly includes a housing, a light source, and a lens disposed in front of the light source, wherein the light source directs light output in a beam towards the lens. The vehicle headlight assembly also includes a light sensor disposed in the housing outside of the beam of light output from the light source directed at the lens for sensing light reflected from moisture on the lens, and a heater disposed on the lens for reducing the moisture.

Embodiments of the third aspect of the invention can include any one or a combination of the following features:the light assembly includes a controller for controlling the heater to heat the lens when moisture is detected with the sensor;the heater comprises an electric heater having a conductive circuit formed on the lens; andthe light assembly includes a light shield located between the light source and the sensor.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring toFIGS. 1-1A, a wheeled motor vehicle10is generally illustrated having moisture sensing and heater or defogging circuitry provided in the vehicle exterior light assemblies. The vehicle10is shown having a pair of vehicle headlight assemblies20located at the front left and right corners of the vehicle10for providing headlight illumination forward of the vehicle10. The vehicle10is also shown having a pair of vehicle taillight assemblies20A located at the rear left and right corners of the vehicle10for providing taillight illumination generally rearward of the vehicle. Each of the headlamp assemblies20and taillight assemblies20A may be configured to include a light detector that provides moisture sensing and a heater arrangement for removal of the moisture from the respective lighting assemblies. It should be appreciated that while each of the headlight assemblies20shown and described herein in detail has the light detector and heater arrangements, the taillight assemblies20A may likewise be configured to include the light sensor and heater arrangements for sensing and removing moisture.

Referring toFIG. 2, the vehicle headlight assembly20is shown having a housing22and an outer lens24which is connected to and may form a part of the housing22. The housing22is generally fixed to the vehicle body and lens24may be connected to housing22in a conventional manner. Disposed within the housing22and outer lens24is a light source26, a reflector28, and an inner lens30. The light source26may include one or more light emitting diodes (LEDs), incandescent bulbs, halogen bulbs, or other sources of light illumination. The reflector28is generally positioned to reflect light output from the light source26forward of the vehicle through the inner lens30and outer lens24to illuminate the roadway generally forward of the vehicle10. The light is output from the inner lens30within a beam32towards the outer lens24and is transmit through the outer lens24, provided the light is not blocked by moisture or other light restricting mediums. The inner lens30and outer lens24may be made of a clear light transmissive polymeric material. The light assembly20may be configured as a low beam light assembly, a high beam light assembly, or a combination of low and high light beam assemblies. Additionally, the housing22and outer lens24may include a plurality of light sources for multiple functions, such as headlight illumination, daylight running lamps, turn signals, flashers, and other lighting functions.

The vehicle light assembly20includes a sensor, in the form of a light sensor40disposed in the housing22for sensing light reflected rearward from the outer lens24caused by moisture on the outer lens24. The light sensor40may be a light-dependent resistor (LDR) or other photo sensor. The light sensor40is located in a region44of the housing22outside of the light beam32output from the light source26and inner lens32and directed at the outer lens24. As such, light generated by the light source26passes through the inner lens30and within beam32to the outer lens24where it is transmitted therethrough and exterior to the vehicle10. In order to help ensure that light generated by the light source26is not directly to the light sensor40, the light sensor40is located in region44with a shield34disposed between both the light source26and the inner lens30and the light sensor40.

The light sensor40senses reflected light42that is reflected off the outer lens24and redirected rearward within the housing22due to moisture build up on the outer lens24. Moisture may be in the form of humidity which is water vapor in the air, or may be in the form of condensation which is water on a surface of the lens24, such as the inner and/or outer surfaces, which can be in the form of liquid water or frozen water (e.g., ice or frost). The build up of condensation or ice or snow on the inner or outer surfaces of the outer lens24blocks light that would otherwise penetrate through the outer lens24and causes at least some of the light to be reflected rearward of the outer lens24as seen by reflected light42. The rearward reflected light42due to moisture on the outer lens24is detected by the light sensor40and processed to determine whether a sufficient amount of moisture has built up on the outer lens24such that a heating operation may be activated to remove the moisture.

In order to heat the outer lens24, a heater50is shown disposed on the outer lens24as seen inFIGS. 3 and 4. The heater50may be formed of a conductive circuit that forms a resistive electrical heater that generates heat when electrical current passes therethrough. The circuitry forming heater50may be configured in various shapes and sizes. As seen inFIG. 4, a defogger voltage VDis applied to a switch SW1at one end of the heater50, while the opposite end of the heater50is shown grounded. Accordingly, when switch SW1is in the closed position, the defroster voltage VDis applied to the heater50to generate an electrical current that passes through the heater50and, due to the electrical resistance, generates thermal energy or heat to defog or defrost the outer lens24. This will cause the condensation on the inside or outside and snow or ice on the outside of the outer lens24to melt and thereby dissipate or be removed when moisture is sensed on the lens24.

The heater50may be printed or otherwise adhered via an adhesive onto the inner surface of the outer lens24, according to various embodiments. According to other embodiments, the heater50may be formed on the outer surface of the lens or an intermediate layer between the inner and outer surfaces of the outer lens24. The conductive material forming the heater50may be formed of an optically or visually transparent conductive material, such as indium tin oxide (ITO), according to one embodiment.

The heater50may be formed with a film of indium tin oxide (ITO). The ITO forming the heater50may be formed as an ink printed onto the interior surface of the outer lens24, according to one embodiment. The ITO may be deposited as a thin film onto the surface of the outer lens24and may have a thickness of about 1,000-3,000 angstroms to form a transparent electrical conductor. The ITO layer forming the heater50is a substantially visually transparent medium that can be used to form a heater element and other conductive signal lines for forming the heater50. As such, the heater50will remain substantially invisible to a user looking through the outer lens24. In other embodiments, other transparent and semi-transparent or visible conductive inks or films may be used to form the heater50.

The vehicle light assembly20advantageously senses moisture build up on the outer lens24by sensing the reflection of light from moisture on the outer lens24as captured or sensed by the light sensor40within housing22, and controls the heater50based on the sensed moisture which is based on the sensed light. Moisture in a liquid form or solid ice form has reflective properties that causes light from beam32to be reflected as reflected light42. The light sensor40detects the reflected light42. When a sufficient amount of moisture is sensed within the light assembly20, the heater50is activated to heat the outer lens24to thereby dissipate and remove the moisture. It should be appreciated that the housing22or lens24may have a moisture outlet, such as a GoreTex® patch to allow heated moisture to exit the interior of the housing22.

Referring toFIG. 5, the heater50is illustrated controlled by a controller60, according to one embodiment. The signal generated by the light sensor40is input to the controller60, such as a microcontroller. The controller60may include circuitry, such as a microprocessor62and memory64. It should be appreciated that other analog and/or digital control circuitry may be employed to process the light sensor signal and to control the heater/defroster50via switch SW1to initiate the defogging and moisture removal process with the activation of the heater50. The microprocessor62may execute the control routine100stored within memory64to control the heater/defroster50operation.

Referring toFIG. 6, routine100is illustrated for sensing moisture on the outer lens and activating the heater, according to one embodiment. Routine100begins at step102and proceeds to step104to set the heating cycle counter to zero and then to step106to measure the amount of light sensed with the light sensor. At decision step108, routine100determines if the amount of sensed light is less than 110% of a factory set value and, if not, returns to step104. When the sensed light is less than 110% of the factory set value, the moisture on the outer lens is assumed to be low or non-existent such that no heating of the lens is needed. It should be appreciated that the factory value may be dependent upon daylight and nighttime ambient lighting conditions, such that a day/night sensor that senses daylight or nightlight conditions may determine if it is daytime or nighttime and may select the corresponding factory set value for daytime or nighttime.

If the amount of sensed reflected light is equal to or greater than 110% of the factory set value, it is assumed that moisture is sensed on the lens and routine100proceeds to step110to initiate heating of the outer lens with activation of the heater for a fixed time period, such as two minutes, and increments the heating cycle counter. Next, at decision step112, routine100determines if the heating cycle counter is less than a preset first count value of 6, for example, and, if so, returns to step106. If the heating cycle counter is at the preset value of 6 or greater, routine100proceeds to decision step114to determine if the ambient temperature is above 32° F., which is the freezing point of water at one atmospheric pressure. If the temperature is not above the freezing point of 32° F., routine100proceeds to decision step116to determine if the heating cycle counter is less than a higher second count value of 15, for example, and, if so, returns to step106. If the temperature is above 32° F. or if the heating cycle counter is not less than a count value of 15, routine100proceeds to decision step118to determine if the rain sensor senses rain or snow in the last ten minutes and, if so, returns to step104. If the rain sensor does not sense rain or snow in the last ten minutes, routine100proceeds to step120to notify the customer on a touchscreen or other human machine interface or output that the headlight may need service, which may be indicative of a scratched lens or other problem that is not necessarily solved by heating the lens24with the heater.

Accordingly, the vehicle light assembly20advantageously employs a light sensor within the housing of the assembly for sensing light reflected rearward due to moisture on the lens to detect the amount of moisture on the lens and controls a heater for heating the lens to remove the moisture. The vehicle light assembly advantageously maintains a low moisture level and minimizes efforts of a driver to maintain a moisture-free lens.