Patent Publication Number: US-2018052321-A1

Title: Light-sensing heads-up display with reflective and emissive modes

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority under 35 U.S.C. §119(e) from U.S. Provisional Patent Application No. 62/143,043, by Kong, “Vehicle Head-Up Display System Utilizing Electronic Paper Display”, filed Mar. 4, 2015, which is incorporated by reference for all purposes. 
    
    
     TECHNICAL FIELD 
     The present invention relates generally to computerized vehicle navigation devices. More particularly, the present invention relates to heads-up display devices for vehicles that use a reflective informational module to create a windshield navigational display when used in bright sunlight. 
     BACKGROUND ART 
     It is an object of the present invention to provide a new and improved technique to provide a vehicle heads-up display system with low power consumption and high visibility in bright sunlight. Attempts at projecting a heads-up display onto the interior of a windshield using standard consumer displays, such as LED or LCD screens, are insufficient to overcome the backlighting of a bright sunny day. Further, attempting to overcome bright daylight with powerful LED projection results in excessive power consumption. A more elegant method of providing vehicle heads-up display in any external lighting condition is sought. 
     DISCLOSURE OF INVENTION 
     A light-sensing heads-up display device for vehicles uses a light sensor to determine when to switch between an emissive mode and a reflective mode. The reflective mode is activated when ambient light sensor detects the vehicle is operating in relatively bright light. The emissive mode is activated when the ambient light sensor detects the vehicle is operating in relative darkness. 
     Because the light-sensing heads-up display device sits on the dashboard of a vehicle, its ambient light sensor determines the intensity of light falling onto to the device through the vehicle windshield, and thus the intensity of backlighting to any heads-up display on the windshield interior. When a windshield brightness trigger event occurs, meaning the light intensity is high enough to indicate that a heads-up up display projected onto to the windshield interior would be more visible using the reflective mode rather than the emissive mode, reflective mode is activated. 
     Reflective mode uses an electronic paper layer to display navigational data on the face of the device. Highly reflective white particles in the electronic paper layer form the letters and images making up the navigational display data, while non-reflective black particles in the electronic paper layer make up the background or negative space of the navigational display. 
     Thus, bright external sunlight, which would overpower light from an LED screen, is made to reflect the navigational display data from the face of the light-sensing heads-up display device. The navigational display data is thereby reflected onto the windshield interior, with brightness comparable to the bright exterior daylight. The navigational display in the electronic paper layer of the device is, naturally, shown in reverse to compensate for its mirroring on the vehicle windshield. 
     Because the electronic paper layer uses power only when moving an electronic ink particle, and not to continuously project light, the heads-up display device can run for weeks on an internal battery. Further, electronic paper reflection allows for high contrast, low display jitter and minimal screen redraw. 
     Sitting below the electronic paper layer, a video layer provides reversed navigational display output when a windshield darkness trigger event is detected by the ambient light sensor. This means the sensed ambient light intensity is low enough to indicate that a heads-up up display projected onto to the windshield interior would be more visible using the emissive mode rather than the reflective mode, as might occur when a vehicle is operating at night, in a tunnel, or on a cloudy day. The video layer is a backlit or sidelit LED layer or LCD layer, or any other light-emitting consumer display capable of fitting into a dashboard device. 
     Emissive mode uses the video layer to project reversed navigational data, which is then seen in mirror image on a driver&#39;s windshield. As with the reflective mode, the navigational display data is shown in bright or white, with the background or negative space left as darkened areas of the LED layer. In order to allow the LED light through, the electronic paper layer above it can be made nearly transparent by scattering its particles or stacking them vertically. 
     Light-sensing heads-up display device receives mapping and other navigation display data and control wirelessly from a smartphone running heads-up display control software. The control software can provide navigation data, such as turns, distances and street names, as well as related information like local speed limits and road conditions. 
     Cognitive visual-spatial display methods incorporated into the control software arrange the textual and graphic elements of the display so as to maximize communication of information with minimize visual distraction to the driver. Further, the control software running on a smartphone or similar device handles voice commands, such that a driver can control the heads-up display without hands leaving the steering wheel. 
     Other methods and structures are described in the detailed description below. This summary does not purport to define the invention. The invention is defined by the claims. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view of an automobile interior showing placement of a light-sensing heads-up display device and a smartphone in accordance with an embodiment of the invention. 
         FIG. 2  is a face view of a light-sensing heads-up display device, unpowered. 
         FIG. 3  is a front face view of a light-sensing heads-up display device, powered and operating in a reflective mode. 
         FIG. 4  is a stylized view of the heads-up display information showing on a glass background, based on the view of  FIG. 3 . 
         FIG. 5  is a front face view of a light-sensing heads-up display device, powered and operating in an emissive mode. 
         FIG. 6  is a stylized view of the heads-up display information showing on a darkened glass background, based on the view of  FIG. 5 . 
         FIG. 7  is a stylized view showing the light-sensing heads-up display device edge-on and heads-up display information on a night-time vehicle windshield. 
         FIG. 8  is a stylized cross-section view showing the arrangement of reflective display module and emissive display module according to the preferred embodiment. 
         FIG. 9  is a stylized cross-section view showing an emissive display module in use. 
     
    
    
     BEST MODE FOR CARRYING OUT INVENTION 
       FIG. 1  is a perspective view of an automobile interior showing placement of a light-sensing heads-up display device and a smartphone in accordance with a preferred embodiment of the invention. 
     The automobile interior view is bounded by a passenger seat  1 , driver&#39;s seat  2 , driver side window  3  and windshield  4 . Interior surfaces labelled in the automobile interior view include the steering wheel  5 , dashboard  6  and center console  7 . 
     Resting on the center console  7  is a smartphone  8 . Said smartphone  8  may be of any type or brand capable of running navigational software and capable of a device-to-device communication method such as Bluetooth, allowing the smartphone to communicate navigation data wirelessly to the light-sensing heads-up display device  9  that rests on the dashboard  6  of an automobile. 
     The back of the light-sensing heads-up display device  9  is affixed to the dashboard  6  of the vehicle by typical methods, such as suction cup or hook-and-loop patch to prevent sliding out of place. Thus, when placed on the dashboard of a typical automobile with a slanted windshield, the face of the light-sensing heads-up display device  9  is within a ninety-degree arc of the windshield interior. 
     The face of the light-sensing heads-up display device  9  is thus reflected on the interior surface of the windshield  6 . Navigation data transmitted wirelessly from the smartphone  7  is filtered and translated via software on-board the light-sensing heads-up display device  9  remove extraneous or distracting information and maximize readability. 
       FIG. 2  is a front face view of the light-sensing heads-up display device  9  of  FIG. 1 , unpowered. The screen  20  of the device is shown darkened and displaying no data. Surrounding the screen  20  is a border portion  21 , typically plastic with, in the preferred embodiment, a matte finish to minimize reflection. A beveled edge may also be employed for the border portion. 
     Also located on the face of the device, within the border portion  21 , is an ambient light sensor  22 . Surface of ambient light sensor  22  is at least parallel with the surface of the screen  20  in the preferred embodiment, or may be angled toward the surface of the screen in order to face ambient sunlight emanating from near the horizon. Ambient light sensor  22  may be co-planar with screen  20 , or may be simply parallel without being co-planar. 
     Because of its purpose as a vehicle windshield display device, the light-sensing heads-up display device  9  is operated entirely by electronic or voice s. An internal control circuit handles included functions, such as electronic communication with external devices and control of electronic paper layer, video layer and ambient light sensor. For this reason,  FIG. 1  indicates that there are no push-buttons, touch-screens, scroll-wheels or other touch controls on the device. This means that the light-sensing heads-up display device  9  is characterized as neither featuring nor using touch controls. 
       FIG. 3  is a front face view of a light-sensing heads-up display device  9 , powered and operating in a reflective mode. In reflective mode, screen  20  employs an electrophoretic layer of electrically charged black and white pigments to produce black, white and grayscale displays, as according to electrophoretic display brands E-Ink or SiPix. Other electronic paper technologies, such electrowetting or electrofluidic, can be used but are considered less effective at presenting a reflection with clear, sharp edges. 
     Reflective mode is activated when light-sensing heads-up display device  9  senses a windshield brightness trigger event via ambient light sensor  22 , which means that light intensity sensing indicates persistent daylight brightness behind the windshield  4  too bright for a video display to be effective. For example, light intensity measured in lux is considered equivalent to full daylight in the range of 10,000 to 32,000 lux. Thus, in the preferred embodiment, a windshield brightness trigger event occurs at 10,000 lux as sensed by the ambient light sensor  22 . Alternate embodiments may set the windshield brightness trigger event as high as 32,000 lux or as low as 8,000 lux. 
     In reflective mode, reflective mode screen display  30  is presented using white electronic ink particles and screen  20  areas empty of display data are left darkened using black electronic ink particles. Reflective mode screen display  30  is characterized as being presented backwards, in reverse from normal orientation for reading. Reflective mode screen display  30  can include destination  31 , directional turn arrow  32 , next street  33 , distance to next turn  34  and destination pointer  35 . Reflective mode screen display  30  can also show auxiliary driving information including fuel gauge  36 , speed  37  and local speed limit  38 . Operational status including automobile connection  39 , smartphone connection  40  and microphone status  41  can also be shown as part of reflective mode screen display  30 . 
     Bright sunlight shining through the windshield is thus reflected from the reflective electronic ink particles of the reflective mode screen display  30  to appear visible to a driver, in mirror image on the windshield. This means that reflective mode screen display  30  is characterized by presenting information, such as text or graphics, optimized for reflectivity and by presenting background or negative display portions as optimized for minimal reflectivity. 
       FIG. 4  is a stylized view of the heads-up display information showing on a stylized glass background  42 , based on the view of  FIG. 3 . Daylight reflected minimally from black or non-reflective electronic ink particles in the display screen produce a translucent and minimally apparent reflection area on the glass  43 . Daylight reflected maximally from white or reflective electronic ink particles in the display screen produce a bright display of information with clear, sharp edges and no flicker. 
     Navigational data on the windshield is thus reflected into proper orientation as reflective mode windshield display  44  and can include destination  45 , directional turn arrow  46 , next street  47 , distance to next turn  48  and destination pointer  49 . Reflective mode windshield display  44  also shows auxiliary driving information including fuel gauge  50 , velocity  51  and local speed limit  52 . Operational status including automobile wireless connection  53 , smartphone wireless connection  54  and microphone status  55  are also shown as part of reflective mode windshield display  44 . 
       FIG. 5  is a front face view of a light-sensing heads-up display device  9 , powered and operating in an emissive mode. In the preferred embodiment, screen  20  employs a backlit LED matrix to produce a night-time navigational display. 
     Emissive mode is activated when light-sensing heads-up display device  9  senses a windshield darkness trigger event via ambient light sensor  22 , which means that ambient light sensing indicates persistent dimness or night behind the windshield  4  too dark for a reflective display to be effective. For example, light intensity measured in lux is considered equivalent to indoor lighting when under 10,000 lux. Thus, in the preferred embodiment, a windshield darkness trigger event occurs at 10,000 lux or less sensed by the ambient light sensor  22  when sensing over that trigger level previously. Alternate embodiments may set the windshield darkness trigger event as high as 32,000 lux or as low as 8,000 lux. 
     In emissive mode, emissive mode screen display  56  is presented using brightly lit portions of a video display module of the screen  20  and null areas of empty of display data are left darkened as dark areas of the video display module. The video display can be triggered to a simple on or off by the windshield darkness trigger event, but the preferred embodiment of the invention sets the brightness of the video display to inverse correlation with the brightness sensed by ambient light sensor  22 . 
     Emissive mode screen display  56  is characterized by being presented reversed and can include destination  57 , directional turn arrow  58 , next street  59 , distance to next turn  60  and destination pointer  61 . Emissive mode screen display  56  can also show auxiliary driving information including fuel gauge  62 , speed  63  and local speed limit  64 . Operational status including automobile wireless  65 , smartphone wireless  66  and microphone status  67  can also be shown as part of emissive mode screen display  56 . 
     Because there is no or little sunlight shining through the windshield  4 , light emitted from the emissive display module of the screen as reversed emissive mode screen display  56  will appear in mirror image on the windshield. 
       FIG. 6  is a stylized view of the heads-up display information showing on a stylized glass background  60 , based on the view of  FIG. 5 . Edge portion of the light-sensing heads-up display device produces no light leaving an area of no reflection on glass. Darkened portions of emissive mode screen display produce a translucent and minimally apparent reflection area  68  on the glass. Brightly lit pixels of the emissive display screen produce a bright display of navigation information which contrast with the exterior darkness. 
     Navigational data on the windshield is thus reflected into proper orientation as emissive mode windshield display  69  and can include destination  70 , directional turn arrow  71 , next street  72 , distance to next turn  73  and destination pointer  74 . Emissive mode windshield display  69  also shows auxiliary driving information including fuel gauge  75 , velocity  76  and local speed limit  77 . Operational status including automobile wireless connection  78 , smartphone wireless connection  79  and microphone status  80  is also included in emissive mode windshield display  69 . 
       FIG. 7  is a stylized view showing the light-sensing heads-up display device  9  edge-on and heads-up navigational display information  81  on a vehicle windshield  4 . 
     According to the preferred embodiment, light-sensing heads-up display device  9  is shown laying flat on vehicle dashboard  6  and secured using adhesive means, as described above in regard to  FIG. 1 . However, in alternate embodiments, the light-sensing heads-up display device  9  may have a shape that angles the face of the device toward the windshield, or the adhesive means may similarly tilt the face of the device toward the windshield. 
     Light-sensing heads-up display device  9  is typically placed just to the side of the driver&#39;s steering display portion  82  of the dashboard  6 . This places the heads-up navigational display information  81  near but not directly in the driver&#39;s line of sight. Placing the light-sensing heads-up display device  9  to the side of, rather than behind, the steering wheel allows ease in removing and replacing the light-sensing heads-up display device  9  when leaving the vehicle. 
     Thus, the light-sensing heads-up display device  9  is configured to lay flat or nearly flat on the windshield. Due to variations in angle of outside light, device placement and windshield curvature heads-up navigational information  81  may display with slight distortions, demonstrated in the figure. These distortions may include mild rotation, shearing or distortions of perspective but are not enough to distract or to obscure the heads-up navigational display information  81 . 
       FIG. 8  is a stylized cross-section view showing the arrangement of reflective display module and emissive display module according to the preferred embodiment. Reflective display module  83  is in use and is shown as a layer of transparent microcapsules sandwiched between transparent layers of chargeable elements. 
     A first microcapsule  85 , in this example, is filled with negatively charged bright, reflective electronic ink particles and positively charged dark, non-reflective electronic ink particles suspended in a liquid. When positive charge is applied to upper chargeable element  88 , the reflective particles are attracted to the upper surface of the microcapsule  85 , just as the non-reflective particles are attracted to the lower surface when a negative charge is applied to lower chargeable element  89 . Second microcapsule  86  is arranged the same way, using positively charged element  90  and negatively charged element  91 . 
     Third microcapsule  87  is arranged in the obverse manner. A negative charge is applied to upper chargeable element  92  so that the non-reflective particles are attracted to the upper surface of the microcapsule  87 , just as the reflective particles are attracted to the lower surface by a positive charge applied to lower chargeable element  93 . 
     Therefore, first lightbeam  94  striking first microcapsule  85  and second lightbeam  95  striking second microcapsule  86  are strongly reflected back toward a vehicle windshield. Third lightbeam  96 , however, strikes third microcapsule  87  and is not reflected. The face of the device above the cross-section view of  FIG. 8  therefore appears to have two bright and one dark pixel, and the bright, reflective pixels are used to make up the reversed text or reverse graphical elements of a reflective mode screen display. 
       FIG. 9  is the stylized cross-section view according to  FIG. 8 , but showing emissive display module  84  in use. Emissive display module is thin, light-emitting layer of any type useable for video displays. In the preferred embodiment, the emissive display module is an LED screen. A first bank of LED elements  96  and a second bank of LED elements  97  are shown darkened. A third bank of LED elements  98  in the emissive display module  84  is activated and emitting light  99 . 
     Above, the reflective display module is put into a transparent mode by the control circuit. In transparent mode, the reflective display module is made transparent, partially transparent or translucent by moving the charged electronic ink particles aside and stacking them vertically. Vertical elements  100  and  102  are negatively charged, attracting the non-reflective electronic ink particles. Vertical elements  101  and  103  are positively charged, attracting the reflective electronic ink particles. 
     The electronic ink particles in the transparent microcapsules are thus arranged to cause little or no obstruction to passage of light emitted from the emissive display module  84 . The face of the device above the cross-section view of  FIG. 9  therefore appears to have two dark pixels  96  and  97  and one bright pixel  98 . The bright pixels are used to make up the reversed text or reverse graphical elements of an emissive mode screen display. 
     It is noted that the described method of making the electronic paper layer transparent is not the only method known in the art. It is, for example, possible to move the microcapsules containing electronic ink pigments or to decohere the pigments by applying heat or voltage to the suspending liquid. The invention also contemplates making use of variable and partial transparency levels possible with electronic ink. 
     Note that the depicted shape of any aspect of the heads-up navigational display information is not the only possible shape. In some embodiments, the ambient light sensor may be a rectangular or square rather than a circle or oval. In over the road vehicles or those with vertical windshields or minimal dashboard space, the device may be secured in place using other methods, such as a set of L-brackets. Control software can run on devices other than a smartphone, such as a vehicle&#39;s on-board computer, a dedicated navigation device, or on the heads-up display device itself. Positive and negative charges of electronic ink elements can, depending on the implementation, be different from the examples shown in  FIG. 8  and  FIG. 9 . It is contemplated that light emitters for the emissive layer may be arranged other than below the reflective layer. And, while wireless communication between the heads-up display is described as using “Bluetooth”, other wireless protocols are possible. 
     Although the present invention has been described in connection with certain specific embodiments for instructional purposes, the present invention is not limited thereto. Accordingly, various modifications, adaptations, and combinations of various features of the described embodiments can be practiced without departing from the scope of the invention as set forth in the claims.