Technical Field

The present disclosure relates generally to a light absorbing film, and in particular, to a structured light absorbing film.

Background

A heads up display (HUD) is used in a vehicle to present information to a vehicle passenger without requiring the passenger to look away from the vehicle surroundings that can be viewed through a vehicle windshield. The HUDs are now increasingly used as a safety feature for vehicles, such as automobiles. Vehicles may also include one or more sensor systems including infrared Light Detection and Ranging (LIDAR) and visible cameras.

Stray light is oblique or scattered light emitted from light sources, such as sun or oncoming vehicles. Stray light often sets a working limit on the sensor systems and the HUD, and further limits signal-to-noise ratio.

Summary

In a first aspect, the present disclosure provides a structured light absorbing film. The structured light absorbing film includes a structured first major surface opposite a second major surface and a light absorbing material dispersed therebetween. The structured first major surface defines an array of cavities formed therein. Each cavity includes opposing first and second side walls intersecting each other at a bottom of the cavity along an intersection line extending along a length of the cavity between opposing first and second ends of the cavity. The first and second side walls make a side angle therebetween less than about 70 degrees. Each cavity further includes opposing first and second end walls disposed at the respective first and second ends of the cavity. The first and second end walls make respective first and second end angles with the intersection line. Each of first and second end angles is greater than about 50 degrees.

In a second aspect, the present disclosure provides an optical system. The optical system includes a light sensor and the structured light absorbing film of the first aspect. The structured light absorbing film is disposed on a surface and is configured to substantially absorb light incident from a light source that would otherwise be reflected by the surface toward the light sensor.

In a third aspect, the present disclosure provides a motor vehicle including the optical system of the second aspect.

In a fourth aspect, the present disclosure provides a heads up display (HUD) for displaying a virtual image to a viewer. The HUD includes the structured light absorbing film of the first aspect.

In a fifth aspect, the present disclosure provides a structured light absorbing film. The structured light absorbing film includes a structured first major surface opposite a second major surface and a light absorbing material dispersed therebetween. The structured first major surface defines an array of cavities formed therein. Each cavity includes a plurality of interior surfaces forming a polyhedron, such that for an incident collimated light incident on the structured first major surface of the structured light absorbing film and making an incident angle of greater than about 40 degrees with a line normal to the structured light absorbing film, the structured light absorbing film reflects a total of less than about 4% of the incident collimated light.

Brief Description of the Drawings

Exemplary embodiments disclosed herein may be more completely understood in consideration of the following detailed description in connection with the following figures. The figures are not necessarily drawn to scale. Like numbers used in the figures refer to like components. However, it will be understood that the use of a number to refer to a component in a given figure is not intended to limit the component in another figure labeled with the same number.

FIG. 1 shows a schematic side view of a structured light absorbing film including an array of cavities according to an embodiment of the present disclosure;

FIG. 2A shows a schematic perspective view of a cavity of the structured light absorbing film according to an embodiment of the present disclosure;

FIG. 2B shows a schematic top view of the array of cavities of FIG. 1 ;FIG. 2C shows a side view of the array of cavities of FIG. 1 ;

FIG. 2D shows a schematic front view of the array of cavities of FIG. 1 ;

FIG. 3 shows a schematic perspective view of a portion of the structured light absorbing film according to an embodiment of the present disclosure;

FIG. 4 shows a schematic side view of an array of cavities according to another embodiment of the present disclosure;

FIG. 5 shows a schematic top view of the array of cavities of FIG. 1 ;

FIG. 6 shows a schematic top view of a structured light absorbing film including an array of cavities according to another embodiment of the present disclosure;

FIG. 7 shows a schematic side view of an exemplary vehicle;

FIG. 8 shows a schematic view of an optical system according to an embodiment of the present disclosure;

FIG. 9 is a schematic view of a three -dimensionally shaped film in accordance with an embodiment of the present disclosure;

FIG. 10 is a schematic view of the structured light absorbing film in a cavity; and

FIG. 11 is a schematic view of a heads up display (HUD) in accordance with an embodiment of the present disclosure.

Detailed Description

In the following description, reference is made to the accompanying figures that form a part thereof and in which various embodiments are shown by way of illustration. It is to be understood that other embodiments are contemplated and may be made without departing from the scope or spirit of the present disclosure. The following detailed description, therefore, is not to be taken in a limiting sense.

The present disclosure relates to a structured light absorbing fdm. The structured light absorbing fdm may be used in an optical system including a light sensor. The structured light absorbing fdm may be configured to substantially absorb light incident from a light source that would otherwise be reflected toward the light sensor. The structured light absorbing film may also be used in a heads up display (herein after referred as “the HUD”). The HUD may be used in various vehicles, such as aircrafts, watercrafts, or land crafts (including motor vehicles, such as automobiles, trucks, and motorcycles).

The structured light absorbing film includes a structured first major surface opposite a second major surface and a light absorbing material dispersed therebetween. The structured first major surface defines an array of cavities formed therein. Each cavity includes opposing first and a second side walls intersecting each other at a bottom of the cavity along an intersection line extending along a length of the cavity between opposing first and second ends of the cavity. The first and second side walls make a side angle therebetween less than about 70 degrees. Each cavity further includes opposing first end and second end walls disposed at the respective first and second ends of the cavity. The first and second end walls make respective first and second end angles with the intersection line. Each of the first and second end angles is greater than about 50 degrees.

Stray light is oblique or scattered light emitted from light sources such as, sun or oncoming vehicles. Stray light often sets a working limit on the optical systems and the HUD. The stray light may further limit signal-to-noise ratio. The structured light absorbing film of the present disclosure may be disposed on a surface or inserted into a cavity. The structured light absorbing film is configured to substantially absorb light incident from the stray light sources that would otherwise be reflected by the surface or an interior surface of the cavity toward a light sensor. Therefore, the structured light absorbing film may reduce or eliminate stray light incident on the light sensor. In other words, the structured light absorbing film may provide stray light mitigation.

Referring now to figures, FIG. 1 is a schematic side view of a structured light absorbing film 200. The structured light absorbing film 200 defines mutually orthogonal x, y, and z-axes. The x and y-axes are in-plane axes of the structured light absorbing film 200, while the z-axis is a transverse axis disposed along a thickness of the structured light absorbing film 200. In other words, the x and y-axes are disposed along a plane of the structured light absorbing film 200, while the z-axis is perpendicular to the plane of the structured light absorbing film 200.

The structured light absorbing film 200 includes a structured first major surface 10 opposite a second major surface 11 and a light absorbing material 20 dispersed therebetween. In some embodiments, the second major surface 11 is substantially planar.

The structured first major surface 10 defines an array of cavities 30 formed therein. In some embodiments, the array of cavities 30 is arranged in rows and columns of the cavities 30. In some embodiments, the array of cavities 30 is arranged in rows of the cavities 30 extending along a first direction and columns of the cavities 30 extending along an orthogonal second direction. In some embodiments, the first direction may be defined along the x-axis, while the second direction may be defined along the y-axis. In some embodiments, the array of cavities 30 includes a regular array of the cavities. In some other embodiments, the array of cavities 30 includes an irregular array of the cavities. In some embodiments, the array of cavities 30 includes a periodic array of the cavities.

In some embodiments, the light absorbing material 20 may include one or more of a light absorbing dye, a light absorbing pigment, and a carbon black dispersed in a binder. The light absorbing dye, the light absorbing pigment, and the carbon black may be dispersed in the binder to provide light absorbing characteristics to the structured light absorbing film 200.

The binder may include one or more of acrylate, polyethylene terephthalate (PET), polycarbonate, polymethylmethacrylate (PMMA), polyvinyl chloride (PVC), polyvinyl alcohol (PVA), polyolefin, polyethylene, polyethylene naphthalate, celluloseacetate, polystyrene, and polyimide. In some embodiments, the binder may further include at least one crosslinker having three or more methacrylate groups and reactive diluents to modify the viscosity of the binder. In some embodiments, the binder may include at least one of a methacrylated urethane oligomer, a methacrylated epoxy oligomer, a methacrylated polyester oligomer, a methacrylated phenolic oligomer, and a methacrylated acrylic oligomer.

In some embodiments, the light absorbing material 20 may be a radiation curable composition. The radiation curable compositions may include at least one photoinitiator.

In some embodiments, the structured light absorbing film 200 may be prepared by a microreplication process.

In some embodiments, the light absorbing material 20 has an absorbance of greater than about 0.2 for at least one wavelength in a range from about 420 nanometers (nm) to about 680 nm. In some other embodiments, the light absorbing material 20 may have an absorbance of greater than about 0.3, greater than about 0.4, or greater than about 0.5 for at least one wavelength in a range from about 420 nm to about 680 nm.

FIG. 2A illustrates a perspective view of the cavity 30 of the structured light absorbing film 200 shown in FIG. 1. One of the cavities 30 is shown in FIG. 2A. The other cavities 30 may be substantially similar to the cavity 30 shown in FIG. 1. FIG. 2B shows a top view of the array of cavities 30. FIG. 2C shows a side view of the array of cavities 30. FIG. 2D shows a front view of the array of cavities 30. The x, y and z axes are shown as dashed lines to distinguish from the edges (shown by solid lines) of the cavity 30. Additional dashed lines are provided for the purpose of illustration.

Referring to FIGS. 1 and 2A-2D, each cavity 30 includes a plurality of interior surfaces forming a polyhedron. The plurality of interior surfaces include opposing first and second side walls 40, 41 and opposing first and second end walls 50, 60.

The first and second side walls 40, 41 intersect each other at a bottom 31 of the cavity 30 along an intersection line 42. In some embodiments, the intersection line 42 is a straight line. The intersection line 42 extends along a length F of the cavity 30 between opposing first and second ends 43, 44 of the cavity 30. The first and second end walls 50, 60 are disposed at the respective first and second ends 43, 44 of the cavity 30. Each of the first and second walls 40, 41 may be substantially planar. Further, each of the first and second walls 50, 60 may be substantially planar. Each of the first and second walls 40, 41 may have a substantially trapezoidal shape. Further, each of the first and second walls 50, 60 has a substantially triangular shape.

The cavity 30 includes vertices A, B, C, D, E and F. The vertex A is formed by the intersection of the first side wall 40 and the first end wall 50. The vertex B is formed by the intersection of the second side wall 41 and the first end wall 50. The vertex D is formed by the intersection of the first side wall 40 and the second end wall 60. The vertex E is formed by the intersection of the second side wall 41 and the second end wall 60. The vertices A, B, D and E may be co-planar. The vertex C is formed by the intersection of the intersection line 42 and the first end wall 50. The vertex F is formed by the intersection of the intersection line 42 and the second end wall 60. The vertices C and F may therefore correspond to ends of the intersection line 42. The vertices A, B and C may be disposed in a plane defined by the first end wall 50. Further, the vertices D, E and F may be disposed in a plane defined by the second end wall 60. The vertices A, B, C, D, E and F are shown in FIGS. 2A-2D and 4 for the purpose of illustration.

The length F may correspond to a distance between the vertices A and D along the x-axis. The length F may also correspond to a distance between the vertices B and E along the x-axis. A width W of each cavity 30 may correspond to a distance between the vertices A and B along the y-axis. The width W may also correspond to a distance between the vertices D and E along the y-axis.

In some embodiments, the length F of each cavity 30 is between about 5 microns to about 2000 microns. In some other embodiments, the length F of each cavity 30 is less than about 500 microns, less than about 1000 microns, or less than about 2000 microns.

In some embodiments, the width W of each cavity 30 is between about 5 microns to about 2000 microns. In some other embodiments, the width W of each cavity 30 is less than about 500 microns, less than about 1000 microns, or less than about 2000 microns.

In some embodiments, the cavities 30 have an average length and an average width. The length F may correspond to the average length of the cavities 30 and is interchangeable referred to as “the average length F”. Similarly, the width W may correspond to the average width of the cavities 30 and is interchangeably referred to as “the average width W”. In some embodiments, a ratio F/W between the average length F and the average width W is greater than about 0.5. In some other embodiments, the ratio F/W between the average length F and the average width W is greater than about 1, greater than about 2, greater than about 5, or greater than about 10.

In some embodiments, the cavities 30 have an average cavity volume of less than about 20 cubic millimeters (mm). However, in some other embodiments, the average cavity volume of the cavities in the array of cavities 30 is less than about 10 cubic mm, less than about 15 cubic mm, less than about 25 cubic mm, or less than about 30 cubic mm.

The first and second side walls 40, 41 make a side angle a therebetween less than about 70 degrees. The side angle a may be defined in the y-z plane. In some embodiments, the side angle a is less than about 60 degrees. In some other embodiments, the side angle a is less than about 50 degrees, less than about 40 degrees, or less than about 30 degrees. In some embodiments, the side angle a is between about 20 and 50 degrees.

As shown in FIG. 2C, the first and second end walls 50, 60 make respective first and second end angles bΐ, b2 with the intersection line 42. The first and second angles may be defined in the x-z plane. Each of the first and second end angles bΐ, b2 is greater than about 50 degrees. In some embodiments, each of the first and second end angles bΐ, b2 is greater than about 60 degrees. In some embodiments, the first end angle bΐ is greater than about 50 degrees and the second end angle b2 is greater than about 70 degrees. In some other embodiments, the first end angle bΐ is greater than about 60 degrees and the second end angle b2 is greater than about 80 degrees. In some embodiments, the first end angle bΐ is between about 60 and 85 degrees and the second end angle b2 is between about 85 and 100 degrees. In some embodiments, the first end angle bΐ is between about 60 and 80 degrees and the second end angle b2 is between about 85 and 95 degrees.

Referring to FIGS. 1 and 2C, for an incident collimated light 70 incident on the structured first major surface 10 of the structured light absorbing film 200 and making an incident angle □ of greater than about 40 degrees with a line 71 normal to the structured light absorbing film 200, the structured light absorbing film 200 reflects a total of less than about 4% of the incident collimated light 70. The line 71 may extend along the z-axis. In some embodiments, for the incident collimated light 70 incident on the structured first major surface 10 of the structured light absorbing film 200 and making the incident angle □ of greater than about 40 degrees with the line 71 normal to the structured light absorbing film 200, the structured light absorbing film 200 reflects less than about 3% of the incident collimated light 70. In some embodiments, for the incident collimated light 70 incident on the structured first major surface 10 of the structured light absorbing film 200 and making the incident angle □ of greater than about 40 degrees with the line 71 normal to the structured light absorbing film 200, the structured light absorbing film 200 reflects less than about 2% of the incident collimated light 70.

In some embodiments, for the incident collimated light 70 incident on the structured first major surface 10 of the structured light absorbing film 200 and making the incident angle □ of greater than about 50 degrees with the line 71 normal to the structured light absorbing film 200, the structured light absorbing film 200 reflects less than about 4% of the incident collimated light 70. In some embodiments, for the incident collimated light 70 incident on the structured first maj or surface 10 of the structured light absorbing film 200 and making the incident angle □ of greater than about 60 degrees, greater than about 70 degrees, or greater than about 80 degrees with the line 71 normal to the structured light absorbing film 200, the structured light absorbing film 200 reflects less than about 4% of the incident collimated light 70.

In some embodiments, the incident collimated light 70 is incident on the structured first major surface 10 of the structured light absorbing film 200 along an incident direction 72 parallel to a plane formed by one of the first and second directions and a third direction orthogonal to the first and second directions. In some embodiments, the third direction may be defined along the z-axis.

FIG. 3 illustrates a portion of the structured light absorbing film 200 including the cavity 30 illustrated in FIG. 2A. The light absorbing material 20 is dispersed in the light absorbing film 200. FIG. 4 illustrates a side view of an array of cavities according to another embodiment of the present disclosure. The structured light absorbing fdm 200 (shown in FIG. 1) includes adjacent first and second cavities 30a, 30b. In this embodiment, the first and second cavities 30a, 30b are spaced apart along the intersection line 42. The first and second cavities 30a, 30b are spaced apart by a distance dl at a top side of the cavities 30a, 30b and a distance d2 at a bottom side of the cavities 30a, 30b.

A ratio dl/d2 between the distance d2 and the distance dl is greater than about 1.5. In some embodiments, the ratio dl/d2 between the distance d2 and the distance dl is greater than about 1.5, greater than about 2, greater than about 3, greater than about 4, greater than about 10, greater than about 50, or greater than about 100.

In some embodiments, the first and second cavities 30a, 30b have an average length M. A ratio M/dl between the average length M and the distance dl is greater than about 10. In some embodiments, the ratio M/d2 between the average length M and the distance dl is greater than about 100, greater than about 500, or greater than about 1000.

FIG. 5 illustrates a schematic top view of the array of cavities 30 of the structured light absorbing film 200 arranged in rows 202 and columns 204. The rows 202 of the cavities 30 extend along the x-axis, while the columns 204 extend along the y-axis. The array of cavities 30 of the structured light absorbing film 200 may include n number of rows 202, where n is 2 or greater. The array of cavities 30 of the structured light absorbing film 200 may include m number of columns 204, where m is 2 or greater. In the illustrated embodiment of FIG. 5, the array of cavities 30 is a regular array of the cavities 30.

FIG. 6 illustrates a schematic top view of another structured light absorbing film 200’ including an array of cavities 30 according to another embodiment of the present disclosure. The structured light absorbing film 200’ is substantially similar to the structured light absorbing film 200 of FIG. 1. However, in the illustrated embodiment of FIG. 6, the array of cavities 30 is an irregular array of the cavities 30.

FIG. 7 illustrates a side view of an exemplary motor vehicle 110 (hereinafter referred to as “the vehicle 110”) that may implement illustrative embodiments of the present disclosure. The vehicle 110 may include any navigable vehicle that may be operated on a road surface, and includes without limitation cars, buses, motorcycles, off-road vehicles, and trucks. In some other embodiments, the vehicle 110 may also include water vehicles and aircrafts. The vehicle 110 includes a windshield 112. The windshield 112 may include any of a wide variety of transparent members, and can be unitary or laminated, flat or curved (simple or compound curvature), water clear or tinted, can have focusing properties (e.g., in the case of goggles or other eyewear), and can be composed of any conventional glasses and/or plastics. In some cases, the windshield 112 may include a sheet of glass or other transparent material with two opposing surfaces. In some embodiments, the vehicle 110 may include an optical system 114 (shown in FIG. 8). In some embodiments, the vehicle 110 may include a HUD 130 (shown in FIG. 11).

FIG. 8 is a schematic view of the optical system 114. The optical system 114 includes a light sensor 80 and the structured light absorbing film 200. The light sensor 80 may be a passive device that converts light into an electrical signal output. The light can be visible light or infra-red light. The light sensor 80 may be referred to as a photoelectric device or a photo sensor. In some embodiments, the light sensor 80 may be disposed proximate to the structured light absorbing fdm 200. In the illustrated embodiment of FIG. 8, the structured light absorbing fdm 200 is disposed on a surface 90. The structured light absorbing fdm 200 may be disposed with the structured first major surface 10 (shown in FIG. 1) facing away from the surface 90. The structured light absorbing fdm 200 is configured to substantially absorb light 101 incident from a light source 100 that would otherwise be reflected by the surface 90 toward the light sensor 80. The light source 100 in the illustrated embodiment is sun. In some other embodiments, the light source 100 may include oncoming vehicles. In some embodiments, the light source 100 may be any source of stray light. The structured light absorbing fdm 200 may therefore reduce or eliminate stray light incident on the light sensor 80. In some other embodiments, the optical system 114 may include the structured light absorbing fdm 200’ (shown in FIG. 6).

FIG. 9 is a schematic view of a three-dimensionally shaped fdm 210. The structured light absorbing fdm 200 (shown in FIG. 1) may be formed into the three-dimensionally shaped fdm 210. In some other embodiments, the structured light absorbing fdm 200’ (shown in FIG. 6) may be formed into the three- dimensionally shaped fdm. In some embodiments, the three-dimensionally shaped fdm 210 may be a conformable fdm. In some embodiments, the three-dimensionally shaped fdm 210 may conform to surfaces that require stray light mitigation. In some embodiments, the three-dimensionally shaped fdm 210 may be a foldable fdm.

FIG. 10 is a schematic view of the structured light absorbing fdm 200 disposed in a cavity 120. In some embodiments, the cavity 120 may be an optical cavity of an optical sensor. As shown in FIG. 10, the structured light absorbing fdm 200 is inserted into the cavity 120. The structured light absorbing fdm 200 substantially conforms to an interior surface 121 of the cavity 120. The structured light absorbing fdm 200 may be disposed with the structured first major surface 10 (shown in FIG. 1) facing an interior of the cavity 120. The structured light absorbing fdm 200 may be configured to substantially absorb light incident from any of the stray light sources that would otherwise be reflected by the interior surface 121 of the cavity 120, thereby providing stray light mitigation. In some embodiments, the structured light absorbing fdm 200 may be folded to any shape, as per application attributes. In some embodiments, the structured light absorbing fdm 200 may be a thermoformable fdm. In some embodiments, the structured light absorbing fdm 200 may be integral with the cavity 120. In some embodiments, the structured light absorbing fdm 200 may be injected molded. In some other embodiments, the structured light absorbing fdm 200’ may be disposed in the cavity 120.

FIG. 11 shows a schematic view of the HUD 130 for displaying a virtual image 131 to a viewer 132. The HUD 130 may be used as a safety feature for vehicles, such as automobiles. The HUD 130 may be used in the vehicle 110 (shown in FIG. 7) to present information to the viewer 132 without requiring the viewer 132 to look away from the surroundings of the vehicle 110 that may be viewed through the windshield 112 (shown in FIG. 7). In some embodiments, the viewer 132 is a driver of the vehicle 110. The HUD 130 may display the information in the driver’s view, so that the driver may not need to look away from the windshield 112 while driving to see the information displayed. The HUD 130 of the vehicle 110 as disclosed in the present disclosure may be configured to, and without limitation, display any type of information, such as map related information, navigation instructions, certain type of warning or alerts, automatic driving assistance information, vehicle’s speed, fuel level, engine temperature, communication events, and other related information on the windshield 112 of the vehicle 110. The display of such information on the windshield 112 of the vehicle 110 may also be represented as and without limitation in any form, such as digital gauges, text boxes, animated images, or any other graphical representation. Further, the HUD 130 of the vehicle 110 may also present augmented reality graphic elements which augment a physical environment surrounding the vehicle with real-time information. The HUD 130 includes the structured light absorbing fdm 200 shown in FIG. 1. The structured light absorbing fdm 200 may be disposed with the structured first major surface 10 (shown in FIG. 1) facing the windshield 112, for example. In some other embodiments, the HUD 130 includes the structured light absorbing film 200’ shown in FIG. 6.

Unless otherwise indicated, all numbers expressing feature sizes, amounts, and physical properties used in the specification and claims are to be understood as being modified by the term “about”. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the foregoing specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by those skilled in the art utilizing the teachings disclosed herein.

Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations can be substituted for the specific embodiments shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the specific embodiments discussed herein. Therefore, it is intended that this disclosure be limited only by the claims and the equivalents thereof.