Patent Publication Number: US-2019187466-A1

Title: Vibration compensating head-up display

Description:
BACKGROUND 
     It is known from the state of the art how to project information in the field of sight of a user, such as, for example, a driver or a pilot, by means of a head-up display, or HUD. 
     One common problem with HUDs is visible disturbances in the image that can result from vibrations that move parts of the HUD such as the combiner. This is especially problematic in vehicular applications, particularly when the vehicle is operating on rough or uneven surfaces such as dirt roads. As a consequence, the projected image can be difficult to be read when the vehicle is running on rough roads. Other sources of vibration such as those that can result from worn and/or unbalanced powertrain components may similarly cause vibrations that result in visible disturbances in a HUD image. 
     There exists a need for a vibration compensating head-up display device that minimizes visible disturbances caused by vibrations. 
     SUMMARY 
     A vibration compensating head-up display device for displaying a projected image superimposed over a field of view of a driver of a vehicle is provided. The head-up display device including an image source generating a signal corresponding to the projected image, a picture generating unit (PGU) generating a light beam to display the projected image upon the combiner panel, and a rotation sensor measuring rotation of the combiner panel about the rotation axis and causing a displacement compensation controller to shift the projected image from a nominal position to a shifted position to offset a displacement of the combiner panel. 
     A method for compensating for vibrations in a head-up display device is also provided. The method includes the steps of providing a combiner panel coupled to a mounting plate and rotatable relative thereto about a rotation axis, generating a projected image by an image source, and projecting the projected image upon the combiner panel. In order to compensate for vibrations affecting the combiner panel, the method proceeds with the steps of measuring rotation of the combiner panel about the rotation axis by a rotation sensor, and shifting the projected image to a shifted position by a displacement compensation controller in response to the measured rotation of the combiner panel. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other advantages of the present invention will be readily appreciated, as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein: 
         FIG. 1A  is a schematic side view of a vibration compensating head-up display device; 
         FIG. 1B  is a is a viewer&#39;s perspective showing a projected image superimposed over a field of view; 
         FIG. 2A  is a cut-away side view of a vibration compensating head-up display device; 
         FIG. 2B  is an enlarged portion of the cut-away side view of  FIG. 2A ; 
         FIG. 3  is a block diagram of one embodiment of a vibration compensating head-up display device; 
         FIG. 4  is a block diagram of another embodiment of a vibration compensating head-up display device; 
         FIG. 5  is a block diagram of another embodiment of a vibration compensating head-up display device; 
         FIG. 6  is a chart showing representative images formed by a vibration compensating head-up display device in three different positions; 
         FIG. 7  is a chart showing a combiner panel in three different positions; 
         FIG. 8  is a chart showing a representative image formed by a vibration compensating head-up display device in three different positions; and 
         FIG. 9  is a flow chart of a method for compensating for vibrations in a head-up display device  20  is also provided 
     
    
    
     DETAILED DESCRIPTION 
     Referring to the Figures, wherein like numerals indicate corresponding parts throughout the several views, a vibration compensating head-up display device  20  is provided. As shown in  FIGS. 1A-1B , the head-up display device  20  displays a projected image  22  superimposed over a field of view of a driver  24  of a vehicle located at an elliptical eye region of space  26  representing a range of normal viewing positions. 
     As shown in  FIG. 2A-2B , the vibration compensating head-up display device  20  includes a mounting plate  28  fixed to the vehicle and supporting a combiner panel  30  of semi-transparent material to display the projected image  22  overlying the field of view. A support  32  including an upper portion  34  and a lower portion  36  sandwiches the combiner panel  30 , holding it in an upright operating position. An axle  38  extends horizontally from the upper portion  34  coupling the combiner panel  30  to the mounting plate  28  and defining a rotation axis A to allow the combiner panel  30  to be rotated relative to the mounting plate  28 . Such rotation of the combiner panel  30  may allow it to be tilted to different positions for adjusting the location of the projected image  22  within the field of view of the driver  24 . Such a tilting functionality may be used, for example, to allow drivers  24  of different heights to adjust the location of the projected image  22  overlying their field of view. The combiner panel  30  may also be rotated about the rotation axis A between an upright operational position and a retracted position when the head-up display device  20  is not in operation. 
     As illustrated in  FIG. 2B , vibrations may also cause the combiner panel  30  to rotate relative to the mounting plate  28 . Such unwanted rotation may cause the resulting image to appear to move or shake. 
     As shown in  FIG. 3 , the vibration compensating head-up display device  20  includes an image source  40  generating a signal corresponding to the projected image  22 . The image source  40  may, for example, be a graphic processor to provide graphical images, numeric, text, or visual images to be displayed by the head-up display. The head-up display device  20  also includes picture generating unit  42  (PGU) in communication with the image source  40  and generating a light beam  44  to display the projected image  22  upon the combiner panel  30 . The picture generating unit  42  may include, for example, a Liquid Crystal on Silicon (LCoS) SLM device as well as one or more illumination sources such as LEDs, lasers or light bulbs. 
     The vibration compensating head-up display device  20  also includes a rotation sensor  46  measuring rotation of the combiner panel  30  about the rotation axis A resulting from vibrations and causing a displacement compensation controller  48  to shift the projected image  22  from a nominal position  50  to a shifted position  52  to offset a displacement of the combiner panel  30  caused by vibration and which would otherwise cause the projected image  22  to appear to move. In this way, unwanted movement of the projected image  22  caused by vibration is effectively cancelled-out. 
     According to the embodiment shown in  FIG. 3 , the rotation sensor  46  communicates a rotation signal  54  to the displacement compensation controller  48  which generates a shifting command  56  which is communicated to the image source  40 , The displacement compensation controller  48  may, for example, determine the timing and the placement of the shifted position  52 , which may be based on, for example, an analysis of the frequency and amplitude of the rotation signal  54 . The image source  40  then generates and transmits a compensated signal  58 , including the projected image  22  in the shifted position  52 . The picture generating unit  42  receives that compensated signal  58 , which it uses to generate and project the projected image  22  onto the combiner panel  30 . 
     According to an alternate embodiment, and as shown in  FIG. 4 , the displacement compensation controller  48  may be functionally combined with the image source  40  such that the image source  40  then generates and transmits the compensated signal  58  in response to the rotation signal  54  from the rotation sensor  46 . In other words, the intermediate step of generating a shifting command  56  is not required. 
     According to another alternate embodiment and as shown in  FIG. 5 , the displacement compensation controller  48  may be functionally disposed between the image source  40  and the picture generating unit  42 . In this way, the image source  40  generates an uncompensated signal  60 , which is subsequently modified by the displacement compensation controller  48  into the compensated signal  58 , including the projected image  22  in the shifted position  52 . 
     As illustrated in FIG,  6 , the shifted position  52  corresponds to a maximum displacement  62  of the combiner panel  30  in either of two opposite directions such as up/down or clockwise/counter-clockwise (CW/CCW) as measured by the rotation sensor  46 . The projected image  22  is not displayed at intermediate positions  64  between the nominal position  50  and the maximum displacement  62 . For example, and as shown in  FIGS. 7-8 , with the combiner panel  30  in a neutral position (step  0 ), the shifted position  52  of the projected image  22  has no offset from the nominal position  50 . In other words, the projected image  22  remains in its centered or nominal position  50 . If the combiner panel  30  moves to a maximum displacement  62  in a first direction (step  1 ), the projected image  22  is moved to the shifted position  52  at a maximum distance from the nominal position  50  and in a second direction opposite the displacement of the combiner panel  30 . Likewise, if the combiner panel  30  moves to a maximum displacement  62  in a second direction (step  2 ), the projected image  22  is moved to the shifted position  52  at a maximum distance from the nominal position  50  and in a first direction opposite the displacement of the combiner panel  30 . In other words, and as illustrated in  FIGS. 7-8 , when the combiner panel  30  moves downward, the displacement compensation controller  48  compensates for such movement by shifting the projected image  22  upward so that the projected image  22  appears to the viewer  24  to remain in the same position. 
     As shown in  FIG. 1A , vibration compensating head-up display device  20  may also include a mirror  66  reflecting the light beam  44  from the picture generating unit  42  onto the combiner panel  30  as a folded optical path. Furthermore, the mirror  66  may be concave to enlarge the projected image  22  as the light beam  44  is reflected. 
     According to an aspect, the rotation sensor  46  may be an angular velocity sensor  46  for measuring the angular velocity of the combiner panel  30  about the rotation axis A. The angular velocity sensor  46  may include a vibration gyro sensor. More specifically, the angular velocity sensor  46  may include a piezoelectric transducer. 
     A method  100  for compensating for vibrations in a head-up display device  20  is also provided. The method  100  includes the steps of  102  providing a combiner panel  30  of semi-transparent material coupled to a mounting plate  28  and rotatable relative thereto about a rotation axis A. For example, and as shown in  FIG. 2A , the combiner panel  30  may include one or more axles  38  extending horizontally therefrom to couple the combiner panel  30  to the mounting plate  28  and defining the rotation axis A to allow the combiner panel  30  to be rotated between different positions relative to the mounting plate  28 . This ability for the combiner panel  30  to be rotated may have several practical applications including, for example, for adjusting the location of the projected image  22  within the field of view of the driver  24  or for moving the combiner panel  30  between an upright operational position and a retracted position when the head-up display device  20  is not in operation. However, the freedom to rotate may also have adverse effects, such as unwanted rotation or displacement caused by vibrations, which may cause visual shaking or wobbles on the head-up display device  20 . 
     The method  100  includes the step of  104  generating a projected image  22  by an image source  40 . The image source  40  may, for example, be a graphic processor to provide graphical images, numeric, text, or visual images to be displayed by the head-up display. The image source  40  may also be a simpler device such as a switched circuit or a digital output signal of a digital controller which may cause a corresponding tell-tale indicator to be illuminated. 
     The method  100  also includes  106  generating a light beam  44  carrying the projected image  22  by a picture generating unit  42  (PGU). The picture generating unit  42  may include, for example, a Liquid Crystal on Silicon (LCoS) SLM device as well as one or more illumination sources such as LEDs, lasers or light bulbs. The picture generating unit  42  may be as simple as an applique or a shape of a symbol defined by the difference in transparency of different materials which may be selectively illuminated to cause a corresponding telltale symbol to be displayed. 
     The method  100  proceeds with  108  reflecting the light beam  44  from the picture generating unit  42  onto the combiner panel  30  by a mirror  66 . The mirror  66  therefore results in the light beam  44  having a folded optical path between the picture generating unit  42  and the combiner panel  30 , which may allow for a more compact packing, which may allow the vibration compensating head-up display device  20  to fit within a given space such as within the dash of a vehicle. Furthermore, the mirror  66  may be concave to enlarge the projected image  22  as the light beam  44  is reflected. 
     The method  100  also includes  110  rotating the combiner panel  30  about the rotation axis A. Such rotation of the combiner panel  30  may allow it to be tilted to different positions for adjusting the location of the projected image  22  within the field of view of the driver  24 . Tilting functionality may be used, for example, to allow drivers  24  of different heights to adjust the location of the projected image  22  overlying their field of view. The combiner panel  30  may also be rotated about the rotation axis A between an upright operational position and a retracted or lowered position when the head-up display device  20  is not in operation, which may protect the combiner panel  30  from exposure to detrimental environmental factors such as dust and/or UV radiation from the sun. 
     The method  100  further includes the step of  112  measuring rotation of the combiner panel  30  about the rotation axis A by a rotation sensor  46 . This step may include, for example, determining the rotation of the combiner panel  30  about the rotation axis A by measuring the angular velocity of the axle  38  by an angular velocity sensor  46 . The angular velocity sensor  46  may include a vibration gyro sensor such as, for example, a piezoelectric vibration gyro sensor. 
     The method  100  proceeds with the step of  114  determining a maximum displacement  62  of the combiner panel  30  in each of two opposite directions as measured by the rotation sensor  46 . The two opposite directions being clockwise and counterclockwise rotation of the combiner panel  30  about the rotation axis A. The maximum displacement  62  may be determined as an averaged maximum value over some time period, which may allow the system to anticipate a maximum displacement that results from regular vibrations such as those having a regular waveform (e.g. a sinusoidal or triangular wave shape). Averaging or filtering the measured rotation values may also help to prevent anomalous or inconsistent operation resulting from inconsistent data from the rotation sensor  46 , which may result, for example, from electrical interference or noise. 
     The method  100  proceeds with the step of  116  displaying the projected image  22  at a shifted position  52  offset from a nominal position  50  and corresponding to the maximum displacement  62  of the combiner panel  30  to compensate for displacement of the combiner panel  30  caused by vibration which would otherwise cause the projected image  22  to appear to move. The shifted position  52  should be configured to offset the change in the position and shape of the projected image  22  that result from the combiner panel  30  being rotated as a result of vibrations. The occurrence of this step is illustrated in  FIGS. 7-8 . 
     The method  100  further includes the step of  118  inhibiting the display of the projected image  22  at intermediate positions  64  between the nominal position  50  and the shifted position  52 . This step is best illustrated in  FIG. 6 . This step is intended to prevent visual anomalies, such as streaking, which could otherwise result from the projected image  22  being shown between the shifted positions  52  and the nominal position  50 . Such visual anomalies may be particularly apparent in eases where the displacement compensation controller  48  is not precisely synchronized with actual vibrations of the combiner panel  30  such as, for example, when a vibration begins or those resulting from changing vibrations such as in rapid transitions between different types of terrain. 
     Obviously, many modifications and variations of the present invention are possible in light of the above teachings and may be practiced otherwise than as specifically described while within the scope of the appended claims.