Patent Publication Number: US-11378248-B2

Title: IR illuminator with secondary function

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation of U.S. application Ser. No. 16/225,924 (US2020/0200356) filed Dec. 18, 2018, the disclosure of which is hereby incorporated in its entirety by reference herein. 
    
    
     TECHNICAL FIELD 
     The present application relates to a lightning module for a motor vehicle, notably an autonomous motor vehicle. The lightning module has a dual function, providing infrared (IR) illumination for the vehicle to assist the operation of a camera and also providing a secondary lighting function for providing visible illumination to assist various signaling functions for the vehicle. 
     DESCRIPTION OF THE RELATED ART 
     Current Autonomous Vehicles (AV) employ a plurality of sensor systems, including camera systems. The camera systems often use IR illuminators to increase the camera performance during nighttime.  FIG. 1  shows typical zones around an AV vehicle which are monitored by vision cameras, and other sensors, for various functions. For example, vision cameras  105 ,  107 ,  109  may be used for traffic sign recognition, lane departure warning, digital side mirror, surround view, rear view mirror, or park assistance. In addition, other sensor systems are used for other functions. Long-range radar may be used for adaptive cruise control; LIDAR  103  may be used for surround sensing, emergency braking, pedestrian detection, or collision avoidance; short/medium-range radar may be used for cross traffic alert, blind spot detection or rear collision warning; and ultrasound/ultra-short-range radar may be used park assistance. 
     In addition, AVs, as well as other conventional vehicles, employ lighting modules emitting visible light that perform a variety of operations needed for the safe operation of the vehicle, such as side marking, warning, etc. For example, side marker lamps enable a driver of another vehicle to see an approaching vehicle, for example, at an angle at night, and take necessary measures in response. 
     Current IR illuminators typically include an IR light emitting diode (LED) and an outer lens which has no refractive optical power. For example,  FIG. 2A  shows a conventional IR illuminator comprising an IR LED  1 , and a neutral flat cover lens  2  that receives the light rays  3  emitted by the IR LED  1  and emits the incident light rays without refraction to the exterior of the IR illuminator. The half-angle emission of the emitted light rays is typically in the 45° to 70° range. The FOV depends on the LED distribution, and type of LED selected. The lens  2  is typically made of polycarbonate (PC) or poly(methyl methacrylate) (PMMA) material. PC is used typically for exterior use of the IR illuminator. In addition, lens  2  may be clear or include additives to make the appearance of the lens black, see  FIG. 2B . However, lens  2  allows IR radiation to pass (“IR black” lens). 
     It is desirable to incorporate in the lighting operation of an AV, both the IR illumination needed for the more efficient operation of the camera and the visible illumination needed for performing various secondary functions. This would allow better integration of the AV lighting functions and systems and also provide space savings for more efficient distribution of the various lighting components of the AV, by integrating visible lighting functions and IR illuminations for the camera in the same module. 
     Thus, a lighting module for an AV is needed that adds additional functionality and value to a conventional IR illuminator. 
     SUMMARY 
     A feature of the present application relates to a lighting module that is used during the operation of AVs to provide improvement in the performance of cameras used in the vehicle at night time. 
     In one non-limiting embodiment, an optical design of an outer lens of an IR illuminator of the lighting module is selected so that the outer lens forms a beam pattern for the output light from an IR light source, and also acts as a light guide for light emitted from a secondary visible light source, which is located in the same module as the IR light source, and which may be positioned on the same or a different printed circuit board (PCB) as the IR light source of the lighting module. The material of outer lens is opalescent including scattering bodies. The optical design of the outer lens allows for improved field of view (FOV) of the IR illuminator. 
     In a further non-limiting embodiment, the IR illuminator includes a feature of adding an additional component to the IR illuminator that guides light emitted by the IR light source. 
     In a further non-limiting embodiment, the IR illuminator includes a feature of the outer lens guiding radiation received by the IR illuminator to a detector inside the IR illuminator. 
     Preferentially, the IR light source of the IR illuminator includes a plurality of IR LEDs, and the secondary light source includes a plurality of visible LEDs, emitting light in the cyan, red, yellow wavelength ranges, as well as RGB LEDs. 
     Preferentially, light from the secondary light source is used to perform secondary functions during the operation of the AV, such as, indication of autonomous mode of operation of the vehicle, warning signaling, or side marking signaling. 
     Due to the optical design of the outer lens and the particular material of the outer lens, the IR illuminator of the present application forms a beam pattern for the IR light with improved FOV, and also acts as a light guide for visible light sources positioned in the same module as the IR light sources. In addition, due to the material of the outer lens, the outer lens can scatter the visible light to make the functional area to glow. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be better understood in light of the description which is given in a non-limiting manner, accompanied by the attached drawings in which: 
         FIG. 1  is a schematic view of an AV illustrating the camera and other sensor-based sensing zones of the vehicle. 
         FIG. 2A  is a schematic view of a conventional IR illuminator with a clear outer lens. 
         FIG. 2B  is a schematic view of a conventional IR illuminator with a black, IR transparent, outer lens. 
         FIG. 3  is a schematic view of an IR illuminator using free form optical concept for increased FOV. 
         FIG. 4A ,  FIG. 4B  and  FIG. 4C  are schematic views of an IR illuminator using free form optical concept for increased FOV with 4 IR LEDs with specifics of the LEDs and the outer lens. 
         FIG. 5  shows graphs that show the improvement of FOV of the IR illuminator due to free form concept design over the conventional outer lens of a conventional IR illuminator. 
         FIG. 6  is a schematic view of an embodiment of an IR illuminator using free form optical concept for increased FOV that provides secondary lighting function, the IR illuminator including an IR LED and a visible LED. 
         FIG. 7A  and  FIG. 7B  show ray tracing graphs for light travelling inside the IR illuminator using free form optical concept with 4 IR LEDs. 
         FIG. 8  is a schematic view of another embodiment of an IR illuminator using free form optical concept for increased FOV that provides secondary lighting function. 
         FIG. 9  is a schematic view of another embodiment of an IR illuminator using free form optical concept for increased FOV that provides secondary function. 
         FIG. 10  is a schematic view of relative positioning between the IR illuminator and a camera in a camera pod. 
         FIG. 11  is a schematic view of different possible relative positions between the IR illuminator and a camera in a camera pod. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 3 , a light module  4  comprises an IR LED  5  that is positioned on a PCB/Sink  6  inside a housing  7 . An outer lens  8  covers one side of the housing  7 . Light rays  9  emitted by IR LED  5  are incident on first surface  10  of lens  8 , are refracted, travel through the body of lens  8 , and exit the second surface  11 . The first and second surfaces of lens  8  are designed to have a free form profile (not a sphere or ellipse) and are not offsets with constant thickness, creating optical power. The shape of the surfaces may also be optimized for light guiding. 
     It is desirable to increase the FOV of the IR illuminator emission pattern and to improve beam uniformity to improve the camera performance for the camera used together with the IR illuminator. The free form profile of the IR illuminator lens  8  allows for the FOV to increase from 140° to 180° (to match the FOV of the camera) and to improve uniformity over the FOV. 
     The above optical concept for the profile of the surfaces of the lens  8  can be used with different numbers of IR LEDs, e.g., 1, 2, 3, 4 . . . . 
     A 4-LED design is shown in  FIG. 4  with information about the specifics of the LEDs and the outer lens. 
       FIG. 5  includes a graph showing the FOV improvement for the free form concept. 
     Referring now to  FIG. 6 , a light module  12  comprises an IR LED  13  that is positioned on a PCB/Sink  14  inside a housing  15 . An outer lens  16  covers one side of the housing  15 . Light rays  17  emitted by IR LED  13  are incident on first surface  18  of lens  16 , are refracted, travel through the body of lens  16 , and exit the second surface  19 . The first and second surfaces of lens  16  are designed to have a free form profile. 
     It is desirable to have the IR illuminator serve a secondary lighting function using the same emitting surface. To achieve this, the free form concept can be enhanced by making the lens of an opalescent material (for example, Evonik Endlighten, or similar) that includes scattering bodies. The optical design may be modified to allow input from a second LED group, without negative impact on the IR performance. The characteristic shape of the free form first and second surfaces of the outer lens  16  allows for efficient light guiding of the secondary LED group. 
     A secondary light source comprising a visible LED  20  is positioned on a PCB  21  inside the housing  15 . The outer lens  16  includes a secondary light guiding section, for example, on the left side, which receives light rays  22  emitted by the visible LED  20  and guides them into the main body of the lens  16 . The light rays  22  exit the lens  16  through the second surface  19 . 
     The secondary light source may include one or more visible LEDs. In non-limiting embodiments, the visible LEDs may be cyan, red, yellow, or RGB (red, green, blue), depending on the particular secondary lighting function desired. 
     For example, a list of possible secondary lighting functions with corresponding visible LEDs as secondary light sources for the IR illuminator includes: 
     Indication of autonomous mode vehicle operation (cyan LED) 
     Signature lighting (user controlled color, RGB LED) 
     Warning (red LED) 
     Side marking (yellow LED at the front of the car, red LED at the back of the car) 
     It is noted that for the IR illuminator with secondary function to be used for side marking, it will need to be positioned (along with the accompanying camera pod) on the car to meet side marker regulations. 
       FIG. 7A  and  FIG. 7B  include ray tracing graphs that show that light from the secondary LEDs is sufficiently guided through the base and over the dome of the outer lens  16 . 
     Referring to  FIG. 8 , another non-limiting embodiment is shown, where both the IR LED  23  and the secondary LEDs  24  are placed on the same PCB  25  inside the housing  26 . In addition, an additional light guide  27 , separate from the outer lens  28  having a free form profile, is positioned to receive light rays from the IR LED  23  and guide them towards the outer lens  28 . The outer lens  28  also receives and guides light rays from the secondary visible LEDs  24 . 
     In another non-limiting embodiment, shown in  FIG. 9 , the secondary, light guiding portion  29  of the outer lens  30  with the free form profile may be used to receive external light  31  and guide it towards a detector  32  inside the IR illuminator  33 . The received light  31  may be ambient light or contain data. For example, the data may be data/software updates. A car may be parked at a charging station and while the car is charging, high speed data is transmitted from a base station to the car (the IR illuminator pod being on the outside of the vehicle). In addition, this embodiment may be used for car-to-car communications as well. 
     The above discussed type of profile for the outer lens for the IR illuminator can be easily adapted to be extruded in linear fashion or in an arc relative to the camera. As shown in  FIG. 10 , the IR illuminator  34  can be placed in a pod linearly with respect to the camera, or it can be placed in an arc fashion to surround the camera (see middle of  FIG. 11 ). The lens optical cross section  34  can be extruded in different ways to make rectangular lenses or round lenses for the corresponding positioning geometries. 
     The sensor system for the AV, that includes the IR illuminator described in the present application, comprises a central unit comprising at least one computer, for example, one or more microprocessors, for implementing the particular driving assistance method, for example, associating the received detector signals from the cameras, radars, LIDAR, etc. with corresponding outputs, e.g., images, sounds, etc., in order to assist in the driving operation of the AV. This central unit may be placed at any location of the motor vehicle, for example, may be integrated into the on-board computer of the motor vehicle. Alternatively, it may be placed within the camera pods. The sensor system further comprises communication means connecting the camera or the other sensors to the central unit, so that images from the cameras or other sensed data are received and processed by the central unit. The central unit further includes imaging processing software for the information necessary for driving assistance. 
     Numerous modifications and variations of the present disclosure are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the described features may be practiced otherwise than as specifically described herein.