Illumination assembly for a vehicle

An illumination assembly for a vehicle. The assembly includes a lamp having a first light source; a first collimator adapted to receive light from the first light source; and an optical wedge, wherein the first collimator is positioned between the first light source and the optical wedge.

TECHNICAL FIELD

This invention generally relates to an illumination assembly for a vehicle.

BACKGROUND

Rearward facing or so-called ‘back-up cameras’ will soon be required on all newly manufactured vehicles. The quality of the image and the data captured by such cameras can vary depending on a number of factors. For example, cameras may gather less data regarding a driver's surroundings based on, among other things, the sensitivity of the camera's detector or imager and operation in darkness or in low-light conditions.

Thus, it is desirable to improve the performance of the camera detector by illuminating a region of interest behind the vehicle so that the camera gathers more light and consequently gathers more data regarding the vehicle's surroundings.

SUMMARY

According to one embodiment of the invention, there is provided an illumination assembly for a vehicle. The assembly includes a housing; at least one light source within the housing; and a cover coupled to the housing and comprising: a planar lens having a plurality of optical elements adapted to receive light from the at least one light source and to direct the light in a first axial direction; and an axially extending light pipe adapted to receive light from the at least one light source and to direct the light in a second axial and opposite direction.

According to another embodiment of the invention, there is provided an illumination assembly for a vehicle. The assembly includes a lamp having a first light source; a first collimator adapted to receive light from the first light source; and an optical wedge, wherein the first collimator is positioned between the first light source and the optical wedge.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An illumination assembly for a rear or tail end of an automotive vehicle is described herein. The illumination assembly may include a license plate lamp (LPL) to illuminate a license plate location, as well as a backup camera lamp (BCL) to provide illumination behind the vehicle for a rearview or backup camera or any other suitable use. In some countries, government regulations define license plate illumination standards (e.g., Federal Motor Vehicle Safety Standard (FMVSS) 108 in the United States). Similarly, some countries have or are developing specifications and/or standards for illuminating predefined regions behind the vehicle—e.g., to increase visibility and detection when using backup cameras and other similar devices, especially where tail lamp (or backup lamps) do not sufficiently illuminate regions directly behind the vehicle. According to one embodiment described below, the BCL illuminates a region directly behind the vehicle, e.g., a region of interest along a vehicle's longitudinal axis.

The illumination assembly is described below with respect to a vehicle environment; however, it should be appreciated that it may be useful in other applications as well. In many vehicle implementations, vehicle manufacturers locate the backup camera along or near a centerline of the vehicle. This minimizes user confusion or adaptation and more closely mimics an actual rearview perception of a vehicle user. The illumination assembly may accommodate a centered backup camera and may, for example, be spaced to the right or left of the centerline, or in other implementations, the illumination assembly may be centered as well. The illumination assembly may or may not include a backup camera; for example, in at least one implementation, the backup camera is a separate module. Also, in the description below, terms of relative direction and position with respect to a vehicle are used for clarity's sake. For example, terms such as “upper,” “lower,” “front,” “rear,” “above,” “below,” and the like, are not intended to be limiting.

FIG. 1illustrates a rear portion10of a vehicle12having a license plate14(in a license plate location15) coupled thereon. In addition, two illumination assemblies16,18schematically are shown proximate to the license plate14, as well as a backup camera20. Each illumination assembly comprises a backup camera lamp (BCL)22and a license plate lamp (LPL)24inboard of the BCL. While two assemblies16,18are shown, some embodiments having only one such illumination assembly are possible. Only assembly16will be described below; however, it should be appreciated that illumination assembly18, when implemented, may be configured as a mirror opposite of assembly16(e.g., so that its LPL24also may be inboard of the BCL22as shown), but in other embodiments it may be located differently, it may not include both LP and BCL, or it may not be used at all.

Illumination assembly16comprises a housing30, a control circuit card or circuit card assembly (CCA)32, and an at least partially transparent cover34, according to one embodiment (seeFIGS. 2-4). Housing30may comprise a body36that includes a rectangular wall38coupled to a curved wall40at a first end42and two pie-shaped end walls46. Opposite the first end42, a second end48of each of the walls38,40,46may terminate at a circumferentially extending flange50. Flange50may be generally rectangular (as shown); however, other shapes are also possible. The flange50includes a bottom surface or edge52which includes an opening54to a cavity56of the housing30(best shown inFIG. 5). Housing30may have other features as well; e.g., as shown inFIG. 2, a connector58for a wiring harness (not shown), one or more appurtenances60for coupling the assembly to the vehicle12, etc.

Cavity56may be defined by a number of inner surfaces70associated with the walls described above, as shown inFIG. 5. At least one of the inner surfaces70may be a reflector or reflective surface72. In the illustrated example, the reflector72is the inner surface of the curved wall40. In general, the housing30may be comprised of a reflective plastic, polymer, or any other suitable material. In one implementation, the reflector72is metallic or a metallic coating. In other implementations, reflector72is merely reflective white plastic.

CCA32may be at least partially carried within the cavity56of the housing30(e.g., on the inner surface70associated with rectangular wall38). But in at least one embodiment, a lower region74of CCA32protrudes through the opening54and may be coupled to the housing30, the cover34, or both.

CCA32may comprise a number of circuit elements76including two light sources78,80carried on the circuit card—e.g., when installed in some implementations, BCL light source (78) and LPL light source (80) may be carried by CCA32facing vehicle rearwardly. In at least one embodiment, the light sources78,80are light emitting diodes (LEDs); however, other suitable light sources are possible. CCA32further may include memory (not shown), a processor (not shown), and various other passive or active circuit elements (not shown) enabling the circuit card32to execute instructions stored on the memory—including instructions for actuation of the light sources78,80. For example, the processor may enable (or switch ON) LPL light source80under low ambient light conditions, when the vehicle running lights are actuated, or any other suitable condition. And the processor may enable (or switch ON) light source78under conditions when the vehicle transmission is placed in “Reverse,” when a vehicle user independently actuates a control associated with the BCL22, or any other suitable circumstance. CCA32described herein may be a single assembly, or in some instances, the card32may comprise multiple circuit card assemblies (e.g., one card carrying light source78and another card carrying light source80). In addition, CCA32is shown as a planarly-shaped circuit card; however, other shapes are possible (e.g., curved or angular shapes having one or more card assemblies).

According to one embodiment (seeFIG. 4), light source80is positioned on CCA32approximately in a middle to upper-middle region84on an inboard side86(of the CCA)—e.g., with respect to a vehicle centerline (not shown), and light source78is positioned in the lower region74of CCA32on an outboard side88(e.g., with respect to the vehicle centerline). In implementations where the CCA32extends out of the cavity56(e.g., seeFIGS. 2-3 and 5), light source80is within the cavity56of the housing30whereas light source78is at least partially below flange50and outside of cavity56.

Cover34may include four walls90arranged vertically in a rectangular shape, a base or planar lens92, and a light pipe94(best shown inFIG. 4). All or part of cover34may be transparent; suitable materials include, but are not limited to, polycarbonate, acrylic (e.g., poly(methyl methacrylate) or PMMA), and/or clear acrylonitrile butadiene styrene (ABS). In at least one embodiment, the walls90, lens92, and light pipe94are formed in a single piece of material. The four illustrated walls90radially extend from the bottom edge52of the housing30to the base92thereby defining a hollow region96(in the cover). Base may be rectangular as well and may have a lip98that extends outwardly of the walls90. Base92is shown as flat; however other implementations are possible. In at least one implementation (FIG. 6), a lower side100of base92includes multiple optical elements or flutes102(e.g., within an inner region104of the lower side100). These flutes102may be arranged and configured to direct light received from light source80(seeFIG. 5) downwardly onto the vehicle license plate14, as will be explained in greater detail below. In one implementation, a portion106of the base lower side100may be smooth; i.e., without flutes102. This smooth portion106may correspond to the location of the light pipe94on cover34.

Inwardly-facing surfaces108and outwardly-facing surfaces110of the walls90may be smooth (FIGS. 2 and 4). On the outwardly-facing surface110which faces vehicle-rearwardly, there may be an optic region120having one or more optical elements or flutes122(thus, this region120may not be smooth). As will be explained more below, these flutes122may be direct light received from light source78rearwardly to provide light for the backup camera20.

Light pipe94may be located in the hollow region96of cover34. Light pipe94may be any suitable longitudinally extending light conduit; in at least one implementation, the light pipe is solid through its diameter (i.e., not hollow). As shown best inFIGS. 4-5, a first end124of the light pipe94may be spaced from the inwardly-facing surface108of one wall90(the vehicle-forward wall) and may extend longitudinally to an opposite wall90(the vehicle-rearward wall)—a second end126of the light pipe corresponding with the optic region120(on the outwardly-facing surface110thereof). The second light source78(on CCA32) may be aligned generally with the first end124of light pipe94so that light (from source78) which enters the first end124may exit at the optic region120. Accordingly to one embodiment, a cross-sectional shape of light pipe94may be arch-like (seeFIG. 2); e.g., a bottom128of the arch-like shape may correspond or coincide with the smooth portion106on the lower side100of base92, and a top130of the arch-like shape may extend upwardly from an upper side132of base92. The height of the light pipe94and the height of the walls90(of cover34) may be approximately the same. The shape of the light pipe94may promote total internal reflectance (TIR) or TIR may be at some value greater than 50%.

During operation, light from light source80may radiate axially and radially outwardly with respect to the longitudinal axis of the vehicle12(and outwardly of CCA32). Upon reaching the curved reflector72, this light is redirected downwardly through the housing30and into the cover34(i.e., radially downwardly with respect to longitudinal axis of the vehicle12). This light is then refracted, reflected, or otherwise redirected onto the license plate14via the flutes102on the base92of cover34.FIG. 8shows that the arrangement of the flutes102may enable license plate illumination sufficient to meet the intensity and uniformity requirements of FMVSS108—e.g., showing test points with minimum illuminance of 13.2 lux (8 lux minimum required) and ratio of 8.7 (20 maximum required). The types of flutes102and the arrangements thereof are known to skilled artisans and will not be elaborated further here. Moreover, it should be appreciated that some implementations will use two illumination assemblies16,18to achieve these requirements; and others will use a single illumination assembly (e.g., such as16).

Light from light source78is radiated axially and radially outwardly as well with respect to the longitudinal axis of the vehicle12(and also outwardly of CCA32). Here, the light source78(and CCA) may be spaced proximate to the first end124of light pipe94so that scatter is minimized. Thus, most of this light is received by the light pipe94and internally reflects therein and exits at the second end126. As discussed above, the second end126has a number of flutes122(in the optic region120) which direct the light vehicle-rearwardly (e.g., in a cone-shaped beam). Again, one or more beams may be used (e.g., from illumination assembly16, illumination assembly18, or both). In either case, the beams may be directed at least partially parallel to the vehicle's longitudinal axis. In some instances, the beams may have a radially inwardly component (i.e., vehicle inboard or e.g., with respect to the vehicle's centerline). Beam direction may be based at least partially upon the arrangement of the flutes122so that backup camera20has sufficient light to provide a user of vehicle12rearview visibility via a display in the vehicle cabin. The shape of the beam(s) and direction thereof may be achieved using flute types and arrangements known to skilled artisans as well.FIG. 9illustrates that in at least one simulation, a region behind vehicle12may be illuminated such that 70% of the light from light source78is directed into the region.

Other implementations also exist. For example,FIG. 7illustrates light pipe94′ which has a curve or bend136along its longitudinal length. This curve enables less of the CCA32to protrude downwardly and be exposed to view (when installed on vehicle12). Thus, in at least one implementation, only a portion of light pipe94′ and the second end126′ thereof drop below the bottom surface52of the housing30. Other implementations could also exist. For example, in one implementation, the light pipe94could extend through a portion of the housing30(e.g., through the curved wall40).

FIGS. 10-17illustrate another implementation of the illumination assembly described above. More specifically,FIG. 10illustrates license plate14and an illumination assembly200that includes a backup camera lamp (BCL)202and a license plate lamp (LPL)204offset from the longitudinal axis or centerline CLof the vehicle. The assembly200further may comprise a housing206and a control circuit card or assembly208. The housing206may include one or more features or appurtenances (not shown) for coupling to BCL202, LPL204, and CCA208. In addition, housing206may also have features or appurtenances (not shown) for coupling to the vehicle (not shown here).

CCA208may be similar to that described above (e.g., CCA32). For example, CCA208may carry at least two light sources210,212—a BCL light source (210) and a LPL light source (212), as best shown inFIG. 11.

As shown inFIGS. 11(front view),12A (side view), and14(top view), BCL202may comprise light source210, a collimator220, and an optical wedge222. As best shown inFIG. 12A, collimator220is a dome optic. The dome optic comprises a body224having a narrow end226extending downwardly to a wide or broad end228. The narrow end226has an opening230to a blind hole232sized to receive the light source210(see sectional view ofFIG. 12B). Hole232may have a generally cylindrical or tapered side wall234and a convex base or bottom236. Collectively, the side wall234and base236comprise a collimator light input238. In some embodiments, light source210also may be coupled to any suitable portion of hole232; in other embodiments, it is only carried by to the CCA208.FIGS. 12A-12Cillustrate a collimator output or exit boundary240at the broad end228that coincides with a light receiving surface or boundary242of optical wedge222.

Optical wedge222may be defined by receiving boundary242, a light transmitting or transmissive surface244, and a light reflecting side246(FIG. 12A). In general, receiving boundary242faces upwardly with respect to vehicle12(e.g., generally parallel to the ground) while transmitting surface244is oriented vertically with respect to the vehicle (e.g., generally normal to the ground). Transmitting surface244may be oriented to face rearwardly with respect to the vehicle, and reflecting side246may face forwardly with respect to the vehicle. In addition, reflecting side246extends from receiving boundary242to transmitting surface244. In addition, a triangular face248may adjoin each of the boundary242, surface244, and reflecting side246on each side of wedge222(see e.g.,FIG. 12A). As will be explained more below, light received into the receiving boundary242may be reflected at an inner reflecting surface250which coincides with the reflecting side246(except that surface250is within wedge222) (seeFIG. 12C).

As best shown inFIGS. 10-11 and 12A, reflecting side246may be curved. In at least one embodiment, the curvature may be a smooth curve having an at least partially parabolic shape. Other embodiments of the light reflecting side246also exist. For example,FIG. 16shows a partial front view of illumination assembly200′ illustrating that a reflecting side246′ of optical wedge222′ may be comprised of multiple facets or surfaces252(note: like numerals denoting same or like elements, features, and functions). In at least one embodiment, the facets252may be circumscribed within the at least partially parabolic curve.

FIG. 12Cschematically illustrates the relationship between the light receiving boundary242, reflecting side246(and consequently inner surface250), and the light transmitting surface244. For example, inner surface250is positioned relative to the receiving boundary242according to an angle (β), the transmitting surface244is positioned relative to the receiving boundary242according to an angle (δ), and the transmitting surface244is positioned relative to inner surface250according to an angle (γ).FIG. 12Calso illustrates two angles labeled as angle (α) or angles of incidence relative to a local normal or 90° angle with respect to inner surface250. In at least one implementation, angle (α) is the critical angle; i.e., it is an angle of incidence above which total internal reflection occurs; and therefore, as will be appreciated by skilled artisans, light rays which meet inner surface250at an angles smaller than the critical angle (α) will pass through or exit the reflecting side246of the wedge222. According to one embodiment, the collimator220and wedge222are configured so that, in general, the angle (α) is 35≤angle (α)≤42.1. And when 35≤angle (α)≤42.1, the angles (β), (γ), and (δ) may vary according to the following suitable ranges: 30≤angle (β)≤50, 40≤angle (γ)≤60, and 80≤angle (δ)≤100. It will be appreciated that angles (β), (γ), and (δ) may be determined based on a desired angle (α), and angle (α) may be determined in part based on a material of the optical wedge222; for example, according to Equation (1) below.
Angle (α)=sin−1(1/n), wherenis the index of refraction of the material  (1)

Turning now to LPL204,FIG. 13illustrates a sectional view of the LPL showing light rays from LPL204onto license plate14. LPL204may comprise the light source212, a collimator260, a frame262, and a lens264. The shape of collimator260may be the same as or substantially similar to the BCL collimator220described above (e.g., including having a hole232and similar features adapted to receive light from light source212). Therefore, the LPL collimator260will not be re-described here.

Frame262may extend from and/or couple to optical wedge222(of the BCL202). Frame262may comprise a planar body266having an upper side268that supports or carries the collimator260. A lower side270of the body266may include or be coupled to the lens264.

Lens264is best illustratedFIG. 13and the bottom view ofFIG. 15. Lens264may include multiple optical elements or flutes280for directing collimated light towards license plate14according to a light distribution pattern that is both adequately even and intense (e.g., per FMVSS 108). In at least one embodiment, optical elements280are pillow-shaped optics. Types and arrangements of optical elements280are known to skilled artisans and may be similar to those described above (e.g., optical elements102of assembly16).

Collimator220and optical wedge222of the BCL202may comprise a material formed in a single-piece construction. Likewise, the collimator260, frame262, and lens264of the LPL204may comprise a material formed in a single-piece construction. Further, the BCL202and LPL204collectively may be formed in a single-piece construction—e.g., formed in a mold using any suitable material. In at least one implementation, the BCL202and LPL204are formed using a polymer. One such suitable polymer may be an acrylic having an index of refraction (n) of 1.492. Other suitable materials include polycarbonate (n=1.586), clear acrylonitrile butadiene styrene (ABS) (n˜1.6), any of the thiourethanes used for eyeglasses (n=1.60-1.74). Of course, these are all merely examples. And in other implementations, all or part of the BCL202and/or LPL204may be machined or otherwise manufactured.

During operation of illumination assembly200, the BCL202may receive un-collimated light from light source210(e.g., a LED) at the collimator input238—e.g., vertically from the LED through an axis of the dome optic. This light may be collimated prior to crossing the light receiving boundary242; i.e., as the rays enter boundary242, the rays may be parallel. The collimated light rays then may pass through the optical wedge222, be redirected at the inner reflecting surface250, and then pass through the transmitting surface244illuminating a rearward region of interest behind the vehicle. The transmitted light may be a high-intensity region or cone of light. In at least one embodiment, BCL202may be configured to aim the light parallel to the ground, rather than at the ground behind the vehicle. In one embodiment, the cone of light may be defined by a transmission axis (not shown) generally parallel to the ground and an angle of divergence (i.e., a deviation from the transmission axis). In some implementations, the angle of divergence, with respect to a transmission axis parallel to the ground, is approximately 40° horizontally and 10° vertically, with respect to the axis associated with transmitting surface244—where the measured divergence is associated with a half-intensity point. This of course is merely one example; other implementations are possible.

During operation, LPL204of the illumination assembly200likewise may receive un-collimated light, but from light source212(e.g., another LED) at its collimator input. Similarly, collimated light may exit the dome optic and may pass into and through frame262. As the light exits the LPL204, it may be refracted via lens264(and optical elements280) towards license plate14. This refracted light may provide a suitably even, predetermined distribution having a suitable intensity (and may be compliant with FMVSS 108).

Other embodiments of illumination assembly200also exist. In one implementation, two illumination assemblies are used (similar to that shown inFIG. 1). The second illumination assembly may be the mirror image of assembly200(e.g., in the second assembly, the BCL may be outboard of the LPL).

According to another embodiment (shown inFIG. 17), two Fresnel collimators300,302may be used instead of dome optic collimators220,260. The Fresnel collimators300,302may be spaced from their respective light sources210,212at predetermined distance(s) (e.g., depending on the arrangement of optics/flutes thereon). Fresnel collimators are merely an example; any other suitable collimators may be used with the LPL frame262and lens264, and with the optical wedge222. Still other implementations will be apparent to skilled artisans.

Thus there has been described an illumination assembly both illuminating a vehicle license plate and illuminating a region of interest behind a vehicle. The license plate may be illuminated according to a predetermined intensity and distribution. And the region of interest may be associated with an orientation of a backup camera so that the backup camera receives more light and thus provides a better quality image to a vehicle user.