Vehicle front lighting assembly and systems having a variable tint electrowetting element

A vehicle front lighting assembly, or headlight assembly, that includes one or more variable tint electrowetting elements overlying a portion of the assembly lens surface. The variable tint electrowetting element is configured to operate to a transparent state whereby the hue of light passing therethrough is not changed, and a tinted state where the hue of light passing therethrough is changed. Alternatively, the variable tint electrowetting element is configured to operate to the tinted state and an opaque state where light is blocked from passing through the electrowetting element. The assembly may use light emitting diodes (LED) as an alternative to more conventional light sources.

TECHNICAL FIELD OF INVENTION

The invention generally relates to vehicle front lighting assemblies, and more particularly relates to a vehicle front lighting assembly that includes a variable tint electrowetting element.

BACKGROUND OF INVENTION

Vehicle lighting assemblies installed on the front end of vehicles generally have distinct bulbs for the headlight and the turn indicator. Light for the turn indicator has a yellow or amber hue so that it can be distinguished from the headlight.

SUMMARY OF THE INVENTION

In accordance with one embodiment of this invention, a vehicle front lighting assembly is provided. The assembly defines a lens surface. The assembly includes a light source and a variable tint electrowetting element. The light source is configured to project light toward the lens surface. The variable tint electrowetting element overlays a portion of the lens surface. The variable tint electrowetting element is operable to a transparent state whereby the hue of light passing therethrough is not substantially changed, and a tinted state where the hue of light passing therethrough is changed.

In accordance with one embodiment of this invention, the variable tint electrowetting element is operable to provide a turn indicator for a vehicle.

In another embodiment of the present invention, a vehicle front lighting system is provided. The system includes a light source and a variable tint electrowetting element. The light source is configured to project light toward a lens surface. The variable tint electrowetting element overlays a portion of the lens surface. The variable tint electrowetting element is operable to a transparent state whereby the hue of light passing therethrough is not substantially changed, and a tinted state where the hue of light passing therethrough is changed; and a controller configured to determine the state of the variable tint electrowetting element based on a light control signal.

In yet another embodiment of the present invention, a vehicle front lighting assembly is provided. The assembly includes a light source configured to project light toward the lens surface. The assembly also includes a variable tint electrowetting element overlying a portion of the lens surface. In this embodiment the variable tint electrowetting element is operable to an opaque state whereby light is prevented from passing therethrough, and a tinted state where the hue of light passing therethrough is changed.

Further features and advantages of the invention will appear more clearly on a reading of the following detailed description of the preferred embodiment of the invention, which is given by way of non-limiting example only and with reference to the accompanying drawings.

DETAILED DESCRIPTION OF INVENTION

FIG. 1illustrates a non-limiting example of a vehicle10equipped with a front lighting assembly12. As used herein, the front lighting assembly12is configured to provide both the forward illumination of a roadway14traveled by the vehicle10in a manner typically associated with a headlight or headlamp, and varying/tinted illumination typically associated with a turn indicator or turn signal. In general, the front lighting assembly12has two sections, a headlight portion16that generally provides forward illumination of the roadway14, and a turn indicator portion18that in this non-limiting example projects amber or yellow light forward and sideways from the vehicle10so a person operating an on-coming or side-approaching vehicle are provided an indication of the intentions of the operator (not shown) of the vehicle10. As will be described in more detail below, an advantage of the front lighting assembly12described herein is that light projected from the turn indicator portion18may be used to supplement light from the headlight portion16for roadway illumination when a turn is not being indicated. Otherwise, light projected from the turn indicator portion18may be variably tinted in a manner that others will readily recognize as an indication that the vehicle10may execute a turn.

FIG. 2illustrates a top cut-away view of a non-limiting example of the front lighting assembly12, corresponding to the drivers-side front lighting assembly shown inFIG. 1. The front lighting assembly12may be equipped with a light source20illustrated here as a single light bulb, for example a halogen light bulb. An advantage of this configuration is that a single light bulb can provide light for both forward roadway14lighting and turn indication. In another embodiment, the light source20may be a light emitting diode, or an array of light emitting diodes. The light source20may be configured to project light toward a lens surface22of a lens24of the vehicle front lighting assembly12. The light, indicated by arrows26, may travel directly from the light source20to the lens surface22, or may be reflected by a reflective surface portion28of the vehicle front lighting assembly12. While the lens24is not illustrated as having any particular light refracting features, such as an arrangement of a plurality of refractive lens elements forming the lens24which is known in the art, this is only for the purpose of simplifying the illustration, and not a limitation. The light source20may be connected to a controller30by, for example, wires32. The combination of the controller30and the vehicle front lighting assembly12may form a vehicle front lighting system34.

The vehicle front lighting assembly12may include a variable tint electrowetting element34overlying a portion of the lens surface22. The variable tint electrowetting element34is, in general, operable to a transparent state or clear state where the hue or color of light from the light source20that passes through the variable tint electrowetting element34is not changed substantially. The variable tint electrowetting element34may also be operable to a tinted state where the hue of light passing through the variable tint electrowetting element34is changed, i.e. tinted or colored.

In general, the variable tint electrowetting element34, includes two fluids: an aqueous fluid, commonly referred to as the water layer; and a hydrophobic dielectric fluid, commonly referred to as the oil layer. In general, the distribution of the oil layer can be manipulated by applying a voltage to electrodes arranged about the variable tint electrowetting element34. If the oil layer material is selected such that light passing through the oil layer is tinted, and the water layer is relatively transparent, then the variable tint electrowetting element34will be operable to variably tint light from the light source20. WO 2011/017446, entitled COLORED CONDUCTIVE FLUIDS FOR ELECTROWETTING AND ELECTROFLUIDIC TECHNOLOGIES, published Feb. 10, 2011 by Clapp et al. provides a description of variable tint electrowetting elements, the entire contents of which are hereby incorporated by reference herein.

In another embodiment, the water layer material may be selected to tint light passing through the variable tint electrowetting element34, and the oil layer material may be an opaque material so as to block light from passing through the variable tint electrowetting element34when the electrical bias is such that the oil layer spreads over the variable tint electrowetting element34. With this configuration, the turn indicator portion18will appear either dark, i.e. not illuminated by the light source20because the light is blocked, or will appear to be illuminated with a tinted or colored light, and so when varied will appear similar to when a turn signal light is alternatingly turned on and off. In another embodiment the opaque material used for the oil layer may also be reflective and so reflect light from the light source20back towards the light source where it may be again reflected to pass through the headlight portion16of the lens24and so further illuminate the roadway14.

The variable tint electrowetting element34may be coupled to the controller30via a connection36formed of, for example, multiple wires. Control signals communicated by the connection36may be voltages to directly control the variable tint electrowetting element34, or may be digitally encoded by the controller30for transmission to the variable tint electrowetting element34that may include another processor (not shown) configured to decode the signal and control the variable tint electrowetting element34accordingly. The controller30may include a processor (not shown) such as a microprocessor or other control circuitry as should be evident to those in the art. The controller30may include memory, including non-volatile memory, such as electrically erasable programmable read-only memory (EEPROM) for storing one or more routines, thresholds and captured data. The one or more routines may be executed by the processor to perform steps for determining control signals output by the controller30for operating the variable tint electrowetting element34as described herein. The controller30may be configured to receive a light control signal38from, for example, a turn signal selector40, and determine the control signal output onto the connection36in order to control the state of the variable tint electrowetting element34based on a light control signal38.

FIG. 3illustrates a non-limiting example of a vehicle front lighting assembly312. Similar toFIG. 1, a lens surface322is segregated into a headlight portion316and a turn signal portion318. In this non-limiting example, a light source320is illustrated as being formed of an array of light emitting diodes. A variable tint electrowetting element334overlies a portion of the lens surface322. The variable tint electrowetting element334is illustrated here as having several variable tint electrowetting cells334A,334B,334C, and334D. Each of the cells generally includes material forming an oil layer350and a water layer352as described above. The illustrations of cells334A and334B suggest that those cells are activated, that is, the oil layer350is spread across the cell, and so the material forming the oil layer is interacting with light from nearby LEDs. In contrast, the illustration of cells334C and334D suggest that those cells are deactivated, that is the oil layer350is crowded into a corner of cell, and so the oil layer350is generally not interacting with light from the nearby LED's

In one embodiment, the oil layer350may comprise a tinting material that colors or tints light passing through oil layer350, and the water layer352may comprise a material that is substantially clear or transparent, and so does not substantially color or tint light passing through the water layer352. For this configuration, light passing through cells334A and334B would be tinted, and light passing through cells334C and334D would not be tinted.

In another embodiment, the oil layer350may comprise an opaque material that prevents light from passing through oil layer350, and the water layer352may comprise a material that is tinted and so colors or tints light passing through the water layer352. For this configuration, light would be blocked from passing through cells334A and334B and so that area of the turn signal portion may appear dark, and light passing through cells334C and334D would be tinted. For either configuration, the variable tint electrowetting element334is operable to provide a turn indicator for a vehicle10. It will be recognized that each of the cells may be independently operated by the controller330.

FIG. 3also illustrates a non-limiting example of several electrowetting prisms354overlying the headlight portion316of the lens surface322. It will be recognized that the arrangement may include more than four electrowetting prisms, that the prisms may also overlay all or part of the variable tint electrowetting element334, and that the prisms may be arranged in a two-dimensional array. Alternatively the vehicle front lighting assembly312may have electrowetting prisms overlying all or some of the variable tint electrowetting element334in the turn signal portion318, with or without electrowetting prism overlaying all or part of the headlight portion316. Electrowetting prisms use a water layer material that has a different index of refraction than the oil layer material, and alter the angle of the water/oil interface to vary a refraction angle as suggested inFIG. 3. For the case where one or more electrowetting prisms overlay all or part of the turn signal portion318, the electrowetting prism may be used to variably direct light passing through the variable tint electrowetting element334. For example, when variable tint electrowetting element334is in a transparent state, light may be directed to illuminate the roadway14and so supplement light from the headlight portion316. Then, when the variable tint electrowetting element334is operated to a tinted state, then light may be directed sideways to provide a brighter turn indication to others not located in front of the vehicle10.

Accordingly, a front lighting assembly12,312, and a controller30for a front lighting system12,312is provided. The front light assembly12provides both forward lighting and turn indication lighting with a single bulb, and so allows for the elimination of a separate turn-signal bulb. Differing materials for the oil layer350and water layer352may be selected to provide a turn indication that, for example, changes from white light to amber light, or changes from no light to amber light, to provide a turn indication. Also, in some configurations, the oil layer350may be a reflective material so that light blocked by the variable tint electrowetting element34,334may be reflected and redirected out of the headlight portion316, and so not waste light energy.