Patent Publication Number: US-2018031740-A1

Title: Self-cleaning optic apparatuses and automobiles with self-cleaning optic apparatuses

Description:
TECHNICAL FIELD 
     The technical field generally relates to optic apparatuses with self-cleaning windows or lenses, and, more specifically, to optic apparatuses in automobiles with self-cleaning windows or lenses for improving driver vision. 
     BACKGROUND 
     Conventional vision aids enabling a driver to monitor the surroundings around an automobile include externally-mounted headlamps (i.e., mounted external of the automobile occupant cabin), externally-mounted side view mirrors and internally-mounted rear view mirrors (i.e., mounted within the automobile occupant cabin). Modern automobiles often utilize externally-mounted rearview or backup video cameras as vision aids for viewing by the driver through a live video display presented on the instrument panel or dashboard. Also, modern automobiles frequently include externally-mounted sensors, such as infrared (IR) sensors that emit and receive IR light, for use in alerting the driver by visual, auditory or tactile alert of close obstruction or an approaching vehicle or pedestrian. 
     Whether a headlamp emitting light, a mirror reflecting light, a camera receiving visible light, or a sensor emitting and receiving IR light, optic devices mounted on an automobile include transparent windows or lenses made of glass or transparent plastic, such as polycarbonate or acrylic. These windows may include a plurality of layers to reduce glare or undesired reflection, depending on use. Typically, a window is mounted or otherwise coupled to a housing that is coupled to the automobile. 
     During use, the windows may become obstructed by dirt or by other particulate that may obscure the desired transmission of light through, or reflection of light from, the windows. For example, in snowy climates, salt, sand, ash, or other substances may be deposited on road surfaces to help melt snow and ice and to increase traction. As a result, a slush may be formed and deposited onto the exterior of vehicles traveling upon such roads. Even a thin layer of slush on a headlamp window significantly decreases the apparent candle power of the headlamp. Likewise, mirrors, cameras and sensors may be rendered effectively useless by slush, dirt, dust or other obstructions on the particular optic device window. 
     Some manufacturers have outfitted optic devices with dedicated wipers on optic device windows. However, such wipers may not be suitable for small size windows such as for mirrors, cameras or sensors. Further, such wipers may be ineffective or prone to breaking or malfunctioning. Even if successful in eliminating obstructions from windows, such wipers add manufacturing cost and may increase costs and complexity in automobile maintenance. 
     Accordingly, it is desirable to provide improved optic apparatuses, such as self-cleaning optic apparatuses. In addition, it is desirable to provide automobiles with self-cleaning optic apparatuses. Furthermore, other desirable features and characteristics will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background. 
     SUMMARY 
     Self-cleaning optic apparatuses and automobiles with self-cleaning optic apparatuses are provided. An exemplary self-cleaning optic apparatus includes an optic device for transmitting or receiving visible light. The optic device is located in a chamber. The self-cleaning optic apparatus further includes a window for transmitting the visible light. Also, the self-cleaning optic apparatus includes a photocatalytic coating on a surface of the window. Energy emitted from within the chamber activates a photocatalytic reaction in the photocatalytic coating. 
     In another embodiment, a self-cleaning optic apparatus includes a housing and a window coupled to the housing and configured to reflect or transmit visible light. Further, the self-cleaning optic apparatus includes a photocatalytic coating on a surface of the window. Also, the self-cleaning optic apparatus includes an energy generating device coupled to the housing and configured to direct energy at the photocatalytic coating on the surface of the window. The energy activates a photocatalytic reaction in the photocatalytic coating. 
     In another embodiment, an automobile with a self-cleaning optic apparatus is provided. The automobile includes a body and a housing coupled to the body and forming a chamber. The automobile includes an optic device located in the chamber and configured to receive visible and/or infrared (IR) light. Further, the automobile includes a window bounding the chamber and configured to transmit the visible and/or IR light to the optic device. Also, the automobile includes a photocatalytic coating on a surface of the window. The automobile further includes an ultraviolet (UV) light generating device coupled to the housing and configured to direct UV light energy at the photocatalytic coating on the surface of the window. The UV light energy activates a photocatalytic reaction in the photocatalytic coating. 
     This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       The embodiments will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and wherein: 
         FIG. 1  is a schematic view of an automobile having a self-cleaning optic apparatus in accordance with an embodiment; 
         FIG. 2  is a cross section view of a self-cleaning optic apparatus of  FIG. 1  in accordance with an embodiment; 
         FIG. 3  is a cross section view of a self-cleaning optic apparatus of  FIG. 1  in accordance with another embodiment; 
         FIG. 4  is a cross section view of a self-cleaning optic apparatus of  FIG. 1  in accordance with another embodiment; and 
         FIG. 5  is a cross section view of a window of a self-cleaning optic apparatus of  FIGS. 2-4  in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     The following detailed description is merely exemplary in nature and is not intended to limit the self-cleaning optic apparatuses and automobiles with self-cleaning optic apparatuses or the application and uses of embodiments described herein. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description. 
     The following description refers to elements or features being “connected” or “coupled” together. As used herein, “connected” may refer to one element/feature being mechanically joined to (or directly communicating with) another element/feature, and not necessarily directly. Likewise, “coupled” may refer to one element/feature being directly or indirectly joined to (or directly or indirectly communicating with) another element/feature, and not necessarily mechanically. However, it should be understood that although two elements may be described below, in one embodiment, as being “connected,” in alternative embodiments similar elements may be “coupled,” and vice versa. Thus, although the schematic diagrams shown herein depict exemplary arrangements of elements, additional intervening elements, devices, features, or components may be present in an actual embodiment. 
     Further, various components and features described herein may be referred to using particular numerical descriptors, such as first, second, third, etc., as well as positional and/or angular descriptors, such as horizontal and vertical. However, such descriptors may be used solely for descriptive purposes relating to drawings and should not be construed as limiting, as the various components may be rearranged in other embodiments. It should also be understood that  FIGS. 1-5  are merely illustrative and may not be drawn to scale. 
       FIG. 1  illustrates a vehicle (or “automobile”)  10  provided with self-cleaning optic apparatuses  20 , according to an embodiment herein. The automobile  10  may be any one of a number of different types of automobiles, such as, for example, a sedan, a wagon, a truck, or a sport utility vehicle (SUV). 
     In the embodiment of  FIG. 1 , the self-cleaning optic apparatus  20  may be an externally-mounted rearview or backup video camera  21 ; a sensor  22 , such as an IR sensor; an externally-mounted side mirror  23 ; and/or a headlamp  24 . Each configuration of the self-cleaning optic apparatus  20 , despite use as a camera  21 , sensor  22 , mirror  23  or headlamp  24 , includes a housing  30  coupled to a body  40  of the automobile  10 . 
       FIG. 2  illustrates, in cross-section view, an exemplary self-cleaning optic apparatus  20 . As shown, the exemplary self-cleaning optic apparatus  20  of  FIG. 2  includes a housing  30  that surrounds a chamber  52 . An optic device  54  is located in the chamber  52 . An exemplary optic device  54  is a camera sensor that receives and records visible light, a lamp that emits visible light, or a sensor that emits and receives IR light. The self-cleaning optic apparatus  20  may include another type of optic device  54  as desired for use. As shown, an electrical connection  56  may be coupled to the optic device  54  and extend out of the chamber  52  to a signal processing device and/or a power source provided elsewhere. 
     The housing  30  further defines an opening  58  through which light may pass into and/or out of the chamber  52 . As shown in  FIG. 2 , a window  60  is positioned in the opening  58  to protect components within the chamber  52 . The window  60  may enhance aerodynamics of the automobile  10 . An exemplary window  60  is formed from a transparent material such as glass or plastic such as polycarbonate. The window  60  may include a plurality of layers of transparent materials and may include gaps between such layers that form vacuums or are filled with gas. The window  60  may be formed as a lens to direct or refract light to a focus. 
     Regardless of the specific structure of the window  60 , the window  60  has an exterior surface  62  and an opposite interior surface  64 . In the embodiment of  FIG. 2 , the interior surface  64  may be considered to enclose the chamber  52  such that the window  60  is external or outside of the chamber  52 . Alternatively, the exterior surface  62  may be considered to enclose the chamber  52  such that the window  60  is within the chamber  52 . In the exemplary embodiment of  FIG. 2 , a seal  66 , such as an O-ring, is located between the window  60  and the housing  30  to seal the chamber  52  and prevent water or other debris from entering the chamber  52 . 
     In the embodiment of  FIG. 2 , the self-cleaning optic apparatus  20  further includes a photocatalytic coating  70  on the exterior surface  62  and/or on the interior surface  64  of the window  60 . A photocatalytic coating  70  on the exterior surface  62  of window  60  may be considered to be an external photocatalytic coating referring to its location relative to chamber  52 . A photocatalytic coating  70  on the interior surface  64  of window  60  may be considered to be an internal photocatalytic coating referring to its location relative to chamber  52 . 
     An exemplary photocatalytic coating  70  is a transparent electrically conductive oxide. For example, the photocatalytic coating  70  may comprise titanium dioxide (TiO 2 ) or other metal oxides such as zinc oxide (ZnO), tin oxide (SnO 2 ), or cerium oxide (CeO 2 ). Titanium dioxide, particularly when it is at least partially crystalline in the “anatase” crystallographic form, serves, under the effect of radiation, particularly ultraviolet radiation, to catalyze the oxidation of organic molecules by free radical reactions. Such oxidation results in the degradation of organic molecules. 
     The underlying physical mechanism of the catalytic oxidation provided by the photocatalytic coating  70  is the creation of an electron-hole pair under the effect of the radiation whereof the energy is greater than or equal to the energy “band gap” between the valence and conduction bands of titanium dioxide. With a band gap of from about 3.2 to about 3.3 EV, a titanium dioxide coating on glass absorbs UV light photons having wavelengths in the range of from about 375 to about 386 nanometers, creating positive holes in the valence band of the titanium dioxide that are known as strong oxidizing entities. 
     Such photocatalytic coatings also have photoinduced hydrophilic properties conferring self-cleaning functions on the coating material. The coating surface made hydrophilic in fact allows for easy cleaning, both of organic waste and inorganic dust, for example by rainwater. This hydrophilic property also confers an anti-fogging effect on the coating material, as water has a tendency to form on the coating material as a transparent film rather than as discrete droplets. Photocatalytic titanium dioxide coatings can be formed by various deposition methods, for example, by chemical vapor deposition (CVD), by cathode sputtering, or by “sol-gel” processes. 
     In the embodiment of  FIG. 2 , the self-cleaning optic apparatus  20  further includes an energy generating device  76 , such as a light energy generating or light generating device. An exemplary light energy generating device  76  generates UV light, though other light energy may be generated if suitable to support the photocatalytic coatings to catalyze oxidation by free radical reactions of organic molecules. In an exemplary embodiment, the light generating device  76  is a light-emitting diode (LED) or a plurality of LEDs. Such light generating devices  76  have low power usage but provide sufficient light energy to support photocatalytic activity of the photocatalytic coating  70 . 
     The light generating device  76  may be oriented to direct light at the photocatalytic coating  70  on the exterior surface  62  and/or at the photocatalytic coating  70  on the interior surface  64  of the window  60  at a desired angle. Alternatively, the self-cleaning optic apparatus  20  may be provided with an optical waveguide or waveguides  78  coupled to the light generating device  76  to direct light energy emitted therefrom onto the photocatalytic coating  70  on the exterior surface  62  and/or onto the photocatalytic coating  70  on the interior surface  64  of the window  60  at a desired angle. For example, the optical waveguide may include fiber optic filament. In an exemplary embodiment, the optical waveguide is annular, i.e., circumferential, and is located outside the periphery of the window  60 . In certain embodiments, the self-cleaning optic apparatus  20  may include a first light generating device  76  dedicated to direct light energy emitted therefrom onto a photocatalytic coating  70  on the exterior surface  62  of the window  60  and a second light generating device  76  dedicated to direct light energy emitted therefrom onto a photocatalytic coating  70  on the interior surface  64  of the window  60 . Such an embodiment may include first and second optical waveguides for directing light onto the respective external or internal photocatalytic coatings  70 . 
       FIG. 3  illustrates, in cross section view, an alternate embodiment in which the self-cleaning optic apparatus  20  is not provided with an optic device  54  and light generating device  76  separately, i.e., not with a dedicated light generating device  76  as in  FIG. 2 . Rather, in  FIG. 3 , the optic device  54  is itself a light generating device  76 . For example, the optic device  54  in  FIG. 3  is a headlamp that generates and transmits light. It is noted that modern headlamps emit visible and UV light. 
     As shown, the exemplary self-cleaning optic apparatus  20  of  FIG. 3  includes a housing  30  and window  60  that surround a chamber  52 . The optic device  54  is located in the chamber  52  and is mounted to the housing  30 . As shown, a photocatalytic coating  70  is located on the exterior surface  62  and on the interior surface  64  of the window  60 . Alternatively, the photocatalytic coating  70  may be located on only one of the surfaces  62  or  64 . An exemplary photocatalytic coating  70  is a transparent electrically conductive oxide such as titanium dioxide (TiO 2 ). During use, UV light from the optic device  54  supports the photocatalytic coatings  70  to catalyze oxidation by free radical reactions of organic molecules. Visible light from the optic device  54  may be transmitted through the window  60  to illuminate areas around the automobile  10  (shown in  FIG. 1 ). 
     Cross-referencing  FIGS. 2 and 3 , it may be seen that the embodiment of the self-cleaning optic apparatus  20  in  FIG. 2  includes a separate light energy generating device  76  to provide energy to the photocatalytic coating  70  to support oxidation and self-cleaning. Alternatively, in the embodiment of  FIG. 3 , the optic device  54  is a headlamp that transmits visible light for illumination and UV light that provides energy to the photocatalytic coating  70  to support oxidation and self-cleaning. 
       FIG. 4  illustrates, in cross section view, another alternate embodiment in which the self-cleaning optic apparatus  20  is not provided with a separate optic device  54  and window  60 . Rather, in  FIG. 4  the optic device  54  is a mirror formed by the window  60  and includes a reflective exterior surface  62 . 
     As shown, the exemplary self-cleaning optic apparatus  20  of  FIG. 4  includes a housing  30 . The housing  30  surrounds a chamber  52  in which the optic device  54  is located. As shown, a photocatalytic coating  70  is located on the reflective exterior surface  62  of the window  60  of the optic device  54 . An exemplary photocatalytic coating  70  is a transparent electrically conductive oxide such as titanium dioxide (TiO 2 ). 
     Further, the self-cleaning optic apparatus  20  includes a light generating device  76 . As shown, the light generating device  76  is coupled to the housing  30  and oriented to direct light onto the photocatalytic coating  70 . An exemplary light generating device  76  generates UV light. An exemplary light generating device  76  is a light-emitting diode (LED) or diodes (LEDs). In the exemplary embodiment, the self-cleaning optic apparatus  20  includes an optic waveguide  78  to direct light from the light generating device  76  onto the photocatalytic coating  70 . An exemplary optic waveguide  78  is annular and surrounds the periphery of the mirrored window  60 . The exemplary optic waveguide  78  may direct UV toward the mirrored window  60  from along the mirror periphery. In an exemplary embodiment, the optic waveguide  78  is in direct contact with the mirrored window  60  along the mirror periphery. If the optic waveguide  78  is not utilized in the embodiment of  FIG. 4 , then the light generating device  76  is directly contacted with the mirrored window  60  along the mirror periphery to direct light onto the photocatalytic coating  70 . 
     Cross-referencing  FIG. 4  with  FIGS. 2 and 3 , it may be seen that the embodiment of the self-cleaning optic apparatus  20  in  FIG. 4  directs energy at the exterior surface  62  of the window  60  from a location outside of the chamber  52  rather than from inside chamber  52 . The light generating device  76  itself may be located within chamber  52  as in  FIGS. 2 and 3 . However, the light energy is transmitted onto the exterior surface  62  of the window  60  from a location outside of the chamber  52 , i.e., on the external side of the exterior surface  62 , in  FIG. 4 . 
       FIG. 5  illustrates, in cross section view, the window  60  of an exemplary self-cleaning optic apparatus  20  in more detail. As shown, the window  60  includes a transparent layer or a plurality of transparent layers that form a transparent substrate  84 . In  FIG. 5 , the window  60  further includes a low refractive index coating  86 . As used herein, a “low refractive index coating” has a refractive index n of about 1.3 or less. An exemplary low refractive index coating may be formed from a stack of dielectric materials. Such a coating  86  may be used to reflect light emitted from the light generating device  76  (shown in  FIGS. 2-4 ) in certain embodiments. For example, for the embodiment of  FIG. 2  that utilizes a camera as the optic device  54 , the light emitted from the light generating device  76  may be reflected within the chamber  52  and then reflected back into contact with the photocatalytic coating  70 . By preventing passage through the window  60  (and loss) of the light emitted from the light generating device  76 , the efficiency of conversion of light generation to photocatalytic activity is raised. It is noted that UV light reflected within the chamber  52  will not have any negative effects on camera imaging of visible light by the optic device  54 . 
     As shown, the photocatalytic coating  70  is located on the exterior surface  62  of the window  60  and on the interior surface  64  (formed by the low refractive index coating  86 ) of the window  60 . In exemplary embodiments, the photocatalytic coating  70  may be located on either or both of the surfaces  62  and  64 . Further,  FIG. 5  illustrates an angle of incidence  92  of light directed onto the photocatalytic coating  70  on interior surface  64  from an interior source, such as a light generating device located in the chamber  52  of the self-cleaning optic apparatus  20  of the embodiment of  FIG. 2 or 3 . Further,  FIG. 5  illustrates an angle of incidence  94  of light directed onto the photocatalytic coating  70  on exterior surface  62  from an interior source, such as a light generating device located in the chamber  52  of the self-cleaning optic apparatus  20  of the embodiment of  FIG. 2 or 3 . Also,  FIG. 5  illustrates an angle of incidence  96  of light directed onto the photocatalytic coating  70  on exterior surface  62  from an exterior source, such as a light generating device of the self-cleaning optic apparatus  20  of the embodiment of  FIG. 4 . 
     In embodiments of the self-cleaning optic apparatus  20  herein, it is contemplated that the angle of incidence  92 , angle of incidence  94 , and/or angle of incidence  96  be greater than about 0°. Further, it is contemplated that angle of incidence  92 , angle of incidence  94 , and/or angle of incidence  96  be less than about 90°, such as less than about 30°, less than about 25°, less than about 25°, less than about 20°, less than about 15°, or less than about 10°. It has been found that directing light onto the photocatalytic coating  70  at a desired angle of incidence improves the efficiency of conversion of light generation to photocatalytic activity. 
     Embodiments provided herein provide for improved self-cleaning of optic devices having windows or lenses that may become obscured by dirt, dust, particulates or other debris. The inclusion of dedicated energy-generating devices for supporting catalytic reactions may be of particular benefit at night when no solar energy is available or for windows or lenses that are downward-facing or otherwise shielded from the sun. Also, embodiments herein are particularly suited for cleaning large or thick accumulations over windows or lenses wherein sunlight is completely blocked and cannot reach the windows or lenses. 
     For an embodiment in which the optic device  54  is a headlamp, such as in  FIG. 3 , the exterior surface  62  of the window  60  may be kept clean from debris through the photocatalytic activity of the coating on the exterior surface. Further, for such an embodiment, condensation on the interior surface of the window  60  is prevented or minimized through the photocatalytic activity of the coating on the interior surface. For an embodiment in which the optic device  54  is a mirror, such as in  FIG. 4 , the exterior reflective surface of the mirror (window) may be kept clean from debris and clear from condensation through the photocatalytic activity of the coating on the exterior surface  62 . 
     While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the disclosure in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing the exemplary embodiment or exemplary embodiments. It should be understood that various changes can be made in the function and arrangement of elements without departing from the scope of the disclosure as set forth in the appended claims and the legal equivalents thereof.