Abstract:
A combiner positioning system for a head-up display includes a carrier and a locking element. The carrier supports a combiner for the head-up display, and the combiner is movable between a stowed position and a display position. The locking element has an engaged position and a disengaged position. The locking element engages a portion of the carrier in the display position and rigidly holds the carrier in the display position.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 13/656,016, filed Oct. 19, 2012, which claims the benefit of U.S. Provisional Application No. 61/549,999, filed Oct. 21, 2011, the entire contents of which are hereby incorporated by reference as if fully set forth. 
     
    
     BACKGROUND 
       [0002]    A head-up display (HUD) is a translucent display panel which may be used to present information to a user without requiring the user to divert his or her gaze from a preferred gaze direction. For example, a HUD may be used to present a driver of a vehicle with a variety of information (e.g., speed, fuel consumption, navigation information, time, etc.) while allowing the driver to simultaneously view traffic conditions and the road in front of the vehicle. 
         [0003]    A typical HUD includes a combiner, a projector, and a visual data source. The combiner is a translucent panel upon which visual data is projected. The combiner usually includes one or more optical coatings that reflect only the specific wavelengths of monochromatic light which are projected by the HUD projector. Thus, the combiner can be conceptualized as a translucent mirror. The HUD projector is positioned relative to the combiner to allow images, graphics, video, or other visual data to be projected onto the combiner. The combiner then reflects the projected images toward the user. 
         [0004]    HUD systems require careful design consideration to ensure reliable performance under a variety of operational conditions. For example, a HUD may be exposed to varying environmental conditions such as high humidity, extreme temperatures, and the presence of contaminants which may cause corrosion. Additionally, when a HUD is implemented in a mobile environment, it is desirable to protect the combiner when the HUD system is inactive to mitigate the potential of damaging the combiner. For this purpose, a positioning system may be used to move the combiner between an active display position and a protected storage position. 
         [0005]    Repeatable positional accuracy is important for combiner positioning systems because an improperly positioned combiner will not function properly in a HUD system. Such positional accuracy may be achieved by using high precision parts which are manufactured and maintained to very close tolerances. However, the need for such close tolerances has the undesirable effect of increasing the manufacture and maintenance expense associated with the positioning system. 
         [0006]    Further, failure to control vibration associated with the combiner may result in a display that is irritating to the user and unpleasant to view over extended periods. Thus, a positioning system is needed which allows the combiner to move between a protected position and a display position and which reduces undesirable vibration to allow for a pleasant viewing experience. 
       SUMMARY 
       [0007]    In one embodiment, a combiner positioning system for a head-up display includes a carrier supporting a combiner for the head-up display, wherein the combiner is movable between a stowed position and a display position; a locking element having an engaged position and a disengaged position, wherein the locking element engages a portion of the carrier and rigidly holds the carrier in the display position, wherein, when the locking element is in the disengaged position, the locking element does not engage the portion of the carrier and does not restrain the carrier from moving laterally, wherein lateral movement of the carrier is required for the combiner to move between the stowed position and the display position. 
         [0008]    In some embodiments, the combiner positioning system further includes an axle extending from the carrier and defining an axis about which the carrier and combiner rotate when in the display position, wherein the locking element urges the axle into a recess and rigidly holds the axle in the recess when in the display position, wherein rigidly holding the axle in the recess increases a resonance frequency of the combiner positioning system. 
         [0009]    In some embodiments, the locking element includes a spring configured to exert a spring force for holding the axle in the display position and in some embodiments the locking element is shaped as a lever comprising a lever axle about which the locking element rotates between the engaged position and the disengaged position. 
         [0010]    In some embodiments, the combiner positioning system further includes a guide element defining a path along which the carrier moves between the stowed position and the display position. The guide element may contained within a housing and may be a slot in the housing a rail protruding from the housing, or any other means for guiding the combiner between the stowed position and display position. 
         [0011]    Additionally, a method of positioning a combiner for a head-up display is disclosed, the method including moving a carrier between a stowed position and a display position, wherein the carrier supports a combiner for the head-up display and engaging a portion of the carrier with a locking element and rigidly holding the carrier in the display position, wherein the locking element, when in a disengaged position, does not engage the carrier and does not restrain the carrier from moving laterally, wherein lateral movement of the carrier is required for the combiner to move between the stowed position and the display position. In some embodiments, the locking element is shaped as a lever comprising a lever axle about which the locking element rotates between the engaged position and the disengaged position. 
         [0012]    In some embodiments, the method further includes urging an axle extending from the carrier into a recess and rigidly holding the axle in the recess when in the display position, wherein rigidly holding the axle in the recess increases a resonance frequency of the positioning system. In some embodiments, a spring may be used to hold the axle in the display position. 
         [0013]    In some embodiments, the method further includes rotating the carrier and combiner about an axis defined by an axle extending from the carrier when in the display position. In some embodiments, the method further comprises disengaging the portion of the carrier with the locking element and moving the carrier from the displayed position to the stowed position. 
         [0014]    In some embodiments, a guide element defines a path along which the carrier moves between the stowed position and the display position. The guide element may be contained within a housing as a slot in the housing, a rail protruding from the housing, or another guiding means. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIG. 1  is a drawing of a head-up display system implemented in a vehicle and shown in the display position. 
           [0016]      FIG. 2A  is a drawing showing a combiner positioning system with the combiner in the display position. 
           [0017]      FIG. 2B  is a drawing showing the combiner positioning system with the combiner in the stowed position. 
           [0018]      FIG. 3  is a drawing showing a half-sectional side perspective view of the combiner positioning system with the combiner in the display position. 
           [0019]      FIG. 4A  is a drawing showing a side view of the combiner positioning system with a locking element in a disengaged position. 
           [0020]      FIG. 4B  is a drawing showing a close-up view of a carrier axle in the display position, with the locking element in the disengaged position. 
           [0021]      FIG. 4C  is a drawing showing a side view of the combiner positioning system with a locking element in an engaged position. 
           [0022]      FIG. 4D  is a drawing showing a close-up view of the carrier axle in the display position, with the locking element in the engaged position. 
           [0023]      FIG. 4E  is a drawing showing the carrier axle rigidly held in a recess by the locking element. 
           [0024]      FIG. 5A  is a drawing showing a half-sectional side perspective view of a camwheel engaging the carrier via a carrier pin extending from the camwheel when the combiner is in the stowed position. 
           [0025]      FIG. 5B  is a drawing showing a half-sectional side perspective view of the carrier pin disengaging from the camwheel with the combiner in the display position. 
           [0026]      FIG. 5C  is a drawing showing a half-sectional side perspective view of an angle adjustment support engaging the carrier with the combiner in the display position. 
           [0027]      FIG. 5D  is a drawing showing a half-sectional side perspective view of the angle adjustment support supporting the carrier in the display position with the combiner fully rotated. 
           [0028]      FIG. 6A  is a drawing of the combiner positioning system showing a flap in a closed position, covering the combiner in the stowed position. 
           [0029]      FIG. 6B  is a drawing of the combiner positioning system showing the flap in an open position and the combiner partially extended between the stowed position and the display position. 
           [0030]      FIG. 7  is a flow chart of a process by which the combiner positioning system operates, including locking the carrier in the display position and rotating the combiner in the display position. 
           [0031]      FIG. 8  is a flow chart of a process by which the combiner positioning system operates, emphasizing the role of the camwheel in engaging the carrier and kinematically driving all sub-processes necessary to move the combiner between the stowed position and the display position. 
       
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0032]    Referring to  FIG. 1 , a HUD system  100  implemented in a vehicle is shown, according to an exemplary embodiment. The HUD system  100  may include a combiner  102  positioned between a driver of the vehicle and the windshield. Combiner  102  may protrude from slot  104  when in a display position and may retract into slot  104  when not in use. 
         [0033]    HUD system  100  may include a combiner  102 . Combiner  102  may be any type of combiner designed for operation in a HUD system or otherwise. For example, combiner  102  may be a translucent or transparent panel formed of a generally planar substrate including transparent or translucent polymers, glass, or other transparent or translucent material. Combiner  102  may be treated with one or more optical coatings selected to reflect specific wavelengths of monochromatic light. Combiner  102  may be a flat panel or may have a curvature. 
         [0034]    Combiner  102  may be used in conjunction with a complete HUD system. In such a configuration, the HUD system may also include a light projector, a controller, or a video generator (not shown). The projector may be used to project visual images (e.g., pictures, graphics, video, text, etc.) received from a video generator onto combiner  102 , which then reflects the visual images to a user. The projector may be located in the dashboard of the vehicle and oriented upward or at an angle to project light toward combiner  102 . However, in other embodiments, the projector may be located elsewhere (e.g., attached to the roof, attached to a visor, etc.) Combiner  102  may be oriented vertically or at an angle such that light projected upon combiner  102  is reflected toward a user. 
         [0035]    Still referring to  FIG. 1 , HUD system  100  may include a slot  104 . Combiner  102  may protrude from slot  104  when in a display position as shown in  FIG. 1 . Additionally, combiner  102  may retract into slot  104  for storage when not in use. Slot  104  may be a hole, slot, gap, space, or other opening through which combiner  102  may extend. Slot  104  may be an opening in an enclosure (e.g., a shell, a frame, a housing, a case, etc.) designed to contain combiner  102 , or may exist in a separate component. A combiner positioning system may be used to transport combiner  102  between a display position and a stowed position.  100361  Referring generally to  FIG. 2A - FIG. 8 , combiner positioning system  200  may move combiner  102  between the stowed position and the display position and rigidly hold combiner  102  in the display position, thereby reducing or eliminating the potential for vibration. Combiner positioning system  200  may use one or more camwheels in conjunction with one or more slots or pins to drive a carrier supporting combiner  102  between the stowed position and the display position. The camwheel(s) may be kinematically linked to a locking element, an angle adjustment support, and/or a flap. Advantageously, all components necessary to transport the combiner between the stowed position and the display position may be operated by the rotation of one or more axially linked camwheels. 
         [0036]    Referring now to  FIG. 2A  and  FIG. 2B , a combiner positioning system  200  is shown, according to an exemplary embodiment.  FIG. 2A  shows combiner positioning system  200  in a display position, whereas  FIG. 2B  shows combiner positioning system  200  in a stowed position. Referring specifically to  FIG. 2A , combiner positioning system  200  may include a carrier  204  for supporting combiner  102 , an axle  206  extending from carrier  204  about which carrier  204  and combiner  102  may rotate when in the display position, and a housing  220  for supporting and/or containing other components of system  200 . 
         [0037]    Still referring to  FIG. 2A , combiner positioning system  200  is shown in a display position. Combiner positioning system  200  may include a carrier  204 . Carrier  204  may be used to support combiner  102  and may be securely attached to combiner  102  to form a unit. Carrier  204  may extend along a length of combiner  102  and may be secured to combiner  102  by any suitable means (e.g., a clamp, a weld, a fastener, a clip, an adhesive compound, a screw, a bolt, etc.). For example, referring to  FIG. 3 , combiner  102  is shown fitted into a slot in carrier  204 . However, in other embodiments, different or additional securing means may be used. In further embodiments, carrier  204  and combiner  102  may be formed into a single component such that no securing or attaching is required. Carrier  204  may have an upper portion for supporting combiner  102  and a lower portion for engaging a mechanism to transport carrier  204  between the stowed position and the display position. 
         [0038]    Referring again to  FIG. 2A , combiner positioning system  200  may further include an axle  206 . Axle  206  may extend from carrier  204  or may be part of carrier  204 . For example, in some embodiments, axle  206  may include two mirrored pins fitted into opposing sides of carrier  204 , defining an axis extending through carrier  204  from one pin to the other pin. In other embodiments, axle  206  may include a single rod extending through carrier  204  along the axis. In further embodiments, axle  206  may be combined with carrier  204  or formed as part of a unitary component including both carrier  204  and axle  206 . The precise structure of axle  206  is not limiting in this regard. 
         [0039]    Still referring to  FIG. 2A , in some embodiments, combiner positioning system  200  may include a housing  220 . Housing  220  may be used to hold, contain, secure, protect, position, mount, fasten, or otherwise locate the various components of combiner positioning system  200 . Housing  220  may be an enclosure, a frame, one or more surfaces, or any other means of orienting, protecting, containing, or positioning one or more elements of system  200 . However, housing  220  is not required and should not be interpreted as a limitation on the scope of invention. 
         [0040]    Referring now to  FIG. 2B , combiner position system  200  is shown to further include one or more camwheels  230 , rotatable about camwheel axis  232 . Camwheels  230  may include a carrier pin  246  for engaging carrier  204  and an angle adjustment support  234 . Combiner positioning system  200  may rotate camwheel  230  and engage carrier  204 , thereby moving carrier  204  and combiner  102  between the stowed position and the display position. Angle adjustment support  234  may be used to adjust the angle of combiner  102  or support carrier  204  when in the display position. 
         [0041]    Still referring to  FIG. 2B , combiner positioning system  200  may include a camwheel  230 . Camwheel  230  may be rotatable about a camwheel axis  232 . In some embodiments, rotation of camwheel  230  about camwheel axis  232  may be accomplished automatically by any type of motor, drive train system, or power system. In other embodiments, camwheel  230  may be manually rotated either directly or via an intermediate means of interaction (e.g., a handle, a crank, a dial, a wheel, etc.). Camwheel  230  may be any type of material including metals, polymers, woods, natural or synthetic compounds, or any other suitable material. Camwheel  230  is shown to be generally cylindrical in shape, wherein the radius of the camwheel cylinder exceeds the length of the cylinder. However, other camwheel shapes may be used (e.g., square, rectangular, triangular, irregular shape, etc.). 
         [0042]    In some embodiments, camwheel  230  may be positioned to one side of combiner  102  (e.g., the left side or right side). However, in other embodiments, multiple camwheels  230  may be used. For example, one camwheel may be positioned on one side of combiner  102  and another camwheel may be positioned on the other side of combiner  102 . If multiple camwheels are used, the camwheels may be connected by a shared camwheel axle extending from one camwheel to another camwheel along camwheel axis  232 . Thus, rotation of one camwheel or the camwheel axle may cause the other camwheel(s) to rotate. Additionally, if multiple camwheels are used, various components of camwheel positioning system  200  may be positioned relative to one or more of the camwheels, as described below. 
         [0043]    Referring now to  FIG. 3 , in some embodiments, combiner positioning system  200  may include a guide element  208 . Guide element  208  may define a path along which axle  206  moves between a display position and a stowed position. In some embodiments, guide element  208  may be a slot or channel within which axle  206  is constrained. In other embodiments, guide element  208  may be a positive extrusion, protrusion, rail, or other guiding element capable of guiding axle  206  between the stowed position and the display position. For example, guide element  208  may be formed into housing  220  as a slot, as shown in  FIG. 3 . However, guide element  208  is optional and is not intended to limit the scope of invention unless recited in the claims 
         [0044]    Referring now to  FIG. 4A - FIG. 4D , combiner positioning system  200  is shown to further include a locking element  210 .  FIG. 4A  and  FIG. 4B  show locking element  210  in a disengaged position and  FIG. 4C  and  FIG. 4D  show locking element  210  in an engaged position. In an exemplary embodiment, locking element  210  may engage axle  206  when combiner  102  is in the display position. Locking element  210  may rigidly hold axle  206  in the display position, thereby reducing the potential for vibration and providing a stable axis about which carrier  204  and combiner  102  may rotate to adjust the display angle of combiner  102 . 
         [0045]    Locking element  210  may increase the resonance frequency or natural frequency of combiner  102 , carrier  204 , or combiner positioning system  200  as a whole by restraining axle  206  from moving laterally (e.g., movement along guide element  208  or otherwise) and by providing increased stiffness (e.g., resistance to movement, rigidity, stability, etc.) when locking element  210  engages carrier  204  in the display position. However, locking element  210  does not prevent carrier  204  and combiner  102  from rotating about an axis defined by axle  206  when in the display position. This allows the display angle of combiner  102  to be adjusted in the display position. 
         [0046]    In some embodiments, locking element  210  may be shaped as a lever having a lever axle  214 . Locking element  210  may rotate about lever axle  214  between a disengaged position (shown in  FIG. 4A  and  FIG. 4B ) and an engaged position (shown in  FIG. 4C  and  FIG. 4D ). However, in other embodiments, locking element  210  may be shaped as a slider, a clip, a ledge, or any other element capable of securing axle  206  in the display position. When locking element  210  is in the disengaged position, axle  206  may freely move between the display position and the stowed position. However, when locking element  210  is in the engaged position, axle  206  is restrained from lateral movement and is only allowed to rotate. 
         [0047]    Referring now to  FIG. 4E , in some embodiments, locking element  210  may urge axle  206  into a recess  212  located at one end of guide element  208 . Recess  212  may provide a secure resting position for axle  206  in the display position. In some embodiments, recess  212  may be a separate fixed or movable part mounted or otherwise rigidly attached to housing  220 . In further embodiments, recess  212  may be incorporated into guide element  208  (e.g., an end of guide element  208  may define recess  212 ) or may be eliminated entirely. Advantageously, recess  212  may be designed to allow carrier  204  and combiner  102  to be removed from housing  220  for repair or replacement without requiring disassembly of the entire combiner positioning system  200 . 
         [0048]    In some embodiments, a spring (not shown) may be attached to locking element  210 . The spring may provide increased resilience for holding axle  206  in the display position when engaged by locking element  210 . In some embodiments, the spring may be located on the opposite side of locking element  210  from axle  206 , thereby providing a compression force urging locking element  210  and axle  206  toward recess  212 . However, in other embodiments, the spring may be located elsewhere (e.g., above recess  212 , on the other side of housing  220 , etc.). In some embodiments, the spring may exert a tension force rather than a compression force, depending on its location, or may be a rotational spring exerting a torque rather than a force. However, in further embodiments, the spring may be eliminated entirely. 
         [0049]    Referring again to  FIG. 4A , camwheel  230  may contain a locking element slot  236 . Locking element slot  236  may be located in one or more camwheel  230  and may be placed on either side of camwheel  230 . 
         [0050]    Referring still to  FIG. 4A , locking element  210  may be coupled to camwheel  230  via a locking element pin  238 . Locking element pin  238  may extend from locking element  210  and may be fitted into locking element slot  236  in camwheel  230 . Locking element pin  238  and locking element slot  236  may be positioned on either side of camwheel  230 . Locking element slot  236  may be substantially circumferentially oriented relative to camwheel  230 . In some embodiments, the radial distance between locking element slot  236  and camwheel axis  232  may vary along the length of the slot  236 . Thus, rotation of camwheel  230  may cause locking element  210  to rotate about lever axle  214 , thereby moving locking element  210  between the engaged position and disengaged position. 
         [0051]    Advantageously, locking element slot  236  may be designed such that locking element  210  engages axle  206  or carrier  204  only when axle  206  is in the display position. Therefore, it may be kinematically impossible for locking element  210  to prematurely move into the engaged position before axle  206  or carrier  204  has reached the display position. 
         [0052]    Referring now to  FIG. 5A  and  FIG. 5B , a side sectional view of combiner positioning system  200  is shown. Referring specifically to  FIG. 5A , camwheel  230  may include a carrier pin  246  extending from the camwheel  230 . As camwheel  230  rotates, carrier pin  246  may engage carrier  204 . As camwheel  230  continues to rotate, carrier  204  may be moved between the stowed position (shown in  FIG. 5A ) and the display position (shown in  FIG. 5B ). 
         [0053]    Referring specifically to  FIG. 5B , in some embodiments, carrier pin  246  may disengage from carrier  204  once carrier  204  has reached the display position. By disengaging carrier pin  246  from carrier  204 , camwheel  230  may further rotate without moving carrier  204  from the display position. 
         [0054]    Referring now to  FIG. 5C , camwheel  230  may include an angle adjustment support  234 . Angle adjustment support  234  may extend from camwheel  230  and may be generally circumferentially oriented around camwheel axis  232 . As camwheel  230  continues to rotate, angle adjustment support  234  may engage carrier  204  in the display position or prior to reaching the display position. In some embodiments, the radial distance between camwheel axis  232  and angle adjustment support  234  may vary along the circumferential length of angle adjustment support  234 . Thus, further rotation of camwheel  230  once angle adjustment support  234  has engaged carrier  204  may cause carrier  204  and combiner  102  to rotate about axle  206 . 
         [0055]    For example, still referring to  FIG. 5C , angle adjustment support  234  is shown engaging carrier  204 . As camwheel  230  continues to rotate, angle adjustment support  234  may move from the position shown in  FIG. 5C  to the position shown in  FIG. 5D . Therefore, angle adjustment support  234  may be used to adjust the angle of combiner  102  when in the display position in order to more accurately reflect projected light toward a user. 
         [0056]    Still referring to  FIG. 5C , in some embodiments, angle adjustment support  234  may be a self-locking element. For example, as camwheel  230  rotates, angle adjustment support  234  may urge, press, or force carrier  204  into the display position due to the varying radial distance between angle adjustment support  234  and camwheel axis  232 . Once in the display position, some or all of the load (e.g., weight, lifting force, torque) necessary to hold carrier  204  in the display position may be transferred to angle adjustment support  234 . Angle adjustment support  234  may rigidly hold carrier  204  in the display position and may be reinforced with ridges  252  extending radially between angle adjustment support  234  and camwheel axis  232 . Reinforcing ridges  252  may stiffen the connection between angle adjustment support  234  and camwheel  230 , thereby increasing the resonance frequency or natural frequency of combiner  102 , carrier  204 , or combiner positioning system  200  as a whole. 
         [0057]    Referring now to  FIG. 6A  and  FIG. 6B , combiner positioning system  200  may include a flap  222 .  FIG. 6A  shows flap  222  in a closed position whereas  FIG. 6B  shows flap  222  in an open position. Flap  222  may cover a slot or gap (e.g., slot  104 ) if combiner positioning system  200  is contained within a housing. Flap  222  may be made of any material, including polymers, metals, woods, glass, synthetic or natural compounds, etc. Flap  222  may be rigid, flexible, semi-flexible, or have any intermediate degree of flexibility. Flap  222  may be opaque, translucent, or transparent and may have any color or visual appearance. 
         [0058]    In some embodiments, flap  222  may move between an open position and a closed position. For example, in the closed position, flap  222  may cover slot  104 , thereby protecting combiner  102  and the other components of combiner positioning system  200  from environmental damage (e.g., pollution, foreign particles, excessive heat, physical, electrical, or chemical damage, etc.). In the open position, flap  222  may retract from, or otherwise expose slot  104  such that combiner  102  may extend through slot  104  into the display position. 
         [0059]    Referring again to  FIG. 4A , flap  222  may be coupled to camwheel  230  via a flap pin  242 . Flap pin  242  may extend from flap  222  and may be fitted into a flap slot  240  in camwheel  230 . Flap pin  242  and flap slot  240  may be positioned on either side of camwheel  230 . Flap slot  240  may be substantially circumferentially oriented relative to camwheel  230 . In some embodiments, the radial distance between flap slot  240  and camwheel axis  232  may vary along the length of the slot  240 . Thus, rotation of camwheel  230  may cause flap pin  242  to move relative to camwheel axis  232  and thereby cause flap  222  to retract from or otherwise expose slot  104 . 
         [0060]    Advantageously, flap slot  240  may be designed (e.g., incorporated into camwheel  230 ) such that flap  222  is withdrawn from slot  104  via rotation of camwheel  230  before combiner  102  is moved into the space previously occupied by flap  222  when moving combiner  102  into the display position. Therefore, it may be kinematically impossible for combiner  102  to contact flap  222  or to extend into the display position before flap  222  has been withdrawn from slot  104 . 
         [0061]    In some embodiments, camwheel  230  may be positioned to one side of combiner  102  (e.g., the left side or right side). However, in other embodiments, multiple camwheels may be used. For example, one camwheel may be positioned on one side of combiner  102  and another camwheel may be positioned on the other side of combiner  102 . If multiple camwheels are used, the camwheels may be connected by a shared camwheel axle extending from one camwheel to another camwheel along camwheel axis  232 . Thus, rotation of one camwheel or the camwheel axle may cause the other camwheel(s) to rotate. 
         [0062]    Additionally, if multiple camwheels are used, the various components of camwheel positioning system  200  (e.g., pins  238 ,  242 , and  246 , slots  236  and  240 , locking element  210 , angle adjustment support  234 , guide element  208 ) may be coupled to one or more of the camwheels. For example, locking element  210  may located on only one side of combiner  102  and may be rotated via locking element slot  236  in the camwheel on that side. On the other side of combiner  102 , angle adjustment support  234  may be used in place of, or in addition to, locking element  210  and locking element slot  236 . 
         [0063]    Referring to  FIG. 7 , a flow chart of a process  700  by which combiner positioning system  200  operates is shown, according to an exemplary embodiment. In brief overview, process  700  may be used to move the combiner between the stowed position and the display position (step  702 ), and engage a portion of the carrier with a locking element and hold the carrier in the display position (step  704 ). Optionally, process  700  may also be used to rotate the carrier about a carrier axis (step  706 ), disengage the portion of the carrier with the locking element (step  708 ), and move the carrier from the display position to the stowed position (step  710 ). Steps shown with broken lines around the edges (e.g., step  706 - 710 ) are optional depending on the particular configuration of the combiner positioning system. 
         [0064]    Still referring to  FIG. 7 , process  700  is shown to include moving a carrier between a stowed position and a display position (step  702 ). In some embodiments, axle  206  may extend from carrier  204  and step  702  may be accomplished by moving axle  206  between the stowed position and display position. In some embodiments, step  702  may include moving axle  206  along guide element  208 , which may be fastened to or embedded in a housing  220 . However, in other embodiments, guide element  208  and housing  220  are unnecessary and may be eliminated. Step  702  may be accomplished using a drive motor or camwheel system to move carrier  204  between the stowed position and the display position. However, in other embodiments, other power systems may be used. 
         [0065]    Still referring to  FIG. 7 , process  700  is shown to further include engaging a portion of the carrier with a locking element and rigidly holding the carrier in the display position (step  704 ). In some embodiments, step  704  may be accomplished using locking element  210  to engage axle  206  when in the display position and rigidly hold axle  206  in place. In some embodiments, locking element  210  may urge axle  206  into a recess  212  located at one end of guide element  208 . However, in other embodiments, recess  212  and guide element  208  are unnecessary. Step  704  may be accomplished using a drive motor or camwheel system to engage the portion of the carrier with the locking element upon reaching the display position. However, in other embodiments, other power systems may be used. 
         [0066]    Process  700  is shown to optionally include rotating the carrier and combiner about an axis defined by an axle extending from the carrier (step  706 ). Step  706  may be performed to adjust the angle of combiner  102  when in the display position in order to more accurately reflect projected light toward a user. Step  706  may be accomplished using a drive motor or camwheel system to rotate carrier  204  and combiner  102  about axle  206 . However, in other embodiments, other power systems may be used. 
         [0067]    Process  700  is further shown to optionally include disengaging the portion of the carrier with the locking element (step  708 ) and moving the carrier from the display position to the stowed position (step  710 ). Steps  708  and  710  may be performed to protect combiner  102  by retracting combiner  102  into housing  220  or another protective component in order to prevent damage to combiner  102  or combiner positioning system  200  when the HUD system is not in use. Step  708  may be accomplished by moving locking element  210  from an engaged position to a disengaged position, thereby allowing axle  206  to move laterally along guiderail  208  or otherwise. If step  706  is optionally performed, it may be necessary to rotate carrier  204  and combiner  102  such that axis  206  may be moved laterally. Then carrier  204  and combiner  102  may be moved from the display position to the stowed position. Step  708  and step  710  may be accomplished using a drive motor or camwheel system to disengage locking element  210 , rotate combiner  102  and carrier  204 , and move combiner  102  and carrier  204  from the display position to the stowed position. However, in other embodiments, other power systems may be used. 
         [0068]    Referring now to  FIG. 8 , a flow chart of a process  800  by which combiner positioning system  200  may operate is shown, according to an exemplary embodiment. In brief overview, process  800  may be used to move the combiner between the stowed position and the display position (step  808 ), engage an axle extending from the carrier with a locking element (step  810 ), engage the carrier with an angle adjustment support (step  814 ), and rotate the carrier about a carrier axis (step  816 ). Steps shown with broken lines around the edges (e.g., step  806 , and  810 - 816 ) are optional depending on the particular configuration of the combiner positioning system. Advantageously, all of steps  804 - 816  are accomplished by rotating camwheel  230  about a camwheel axis (step  802 ). In other words, step  802  kinematically drives all other steps of process  800 . 
         [0069]    For example, rotating camwheel  230  (step  802 ) may cause carrier pin  246  to engage carrier  204  (step  804 ) and move carrier  204  along with combiner  102  between the stowed position and the display position (step  808 ). Optionally, if flap  222  is used in combiner positioning system  200 , rotating camwheel  230  may also cause flap  222  to move between an open position and closed position (step  806 ) prior to moving combiner  102  into the display position (step  808 ). However, if combiner  102  is being moved from the display position to the stowed position, step  806  would occur after step  808 , as the process would be performed in reverse order. 
         [0070]    Still referring to  FIG. 8 , process  800  may include one or more of optional steps  810 - 814 , all of which are also accomplished by continuing to rotate camwheel  230 . For example, process  800  may include engaging an axle  206  extending from the carrier  204  with a locking element  210  (step  810 ). Continued rotation of camwheel  230  may accomplish step  810  by rotating locking element  210  between a disengaged position (shown in  FIGS. 4A-4B ) and an engaged position (shown in  FIGS. 4C-4D ) as locking element pin  238  slides along locking element slot  236 . 
         [0071]    Locking element  210  may discharge the force exerted on carrier pin  246 , thereby allowing carrier pin  246  to disengage from carrier  204  (step  812 ). Once carrier pin  246  has disengaged, camwheel  230  may continue to rotate without affecting the lateral position of carrier  204 . 
         [0072]    Process  800  may also include engaging the carrier  204  with an angle adjustment support  234  (step  814 ) as shown in  FIG. 5C  and  FIG. 5D . Angle adjustment support  234  may perform a similar function to locking element  210  by restraining carrier  204  and combiner  102  in the display position (e.g., preventing lateral movement). Additionally, due to the varying radial distance between angle adjustment support  234  and camwheel axis  232  (i.e., one end of angle adjustment support  234  may be closer to axis  232  than the other end), angle adjustment support  234  may cause carrier  204  and combiner  102  to rotate about a carrier axis (step  816 ) as camwheel  230  continues to rotate. 
         [0073]    Advantageously, all steps of process  800  are driven by the rotation of camwheel  230 . By rotating camwheel  230  in one direction, all steps necessary to move combiner  102  from the stowed position to the display position, and also several optional steps, are kinematically carried out. Because all moving parts (e.g., pins, levers, support structures, etc.) are directly connected to one or more camwheels, no intermediate elements (e.g., additional gears, wheels, levers, etc.) are required. In other words, all movement, whether rotational, linear, or a combination thereof, are kinematically caused by the rotation of one or more axially coupled camwheels. 
         [0074]    The construction and arrangement of the systems and methods as shown in the various exemplary embodiments are illustrative only. Although only a few embodiments have been described in detail in this disclosure, many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations, etc.). For example, the position of elements may be reversed or otherwise varied and the nature or number of discrete elements or positions may be altered or varied. Accordingly, all such modifications are intended to be included within the scope of the present disclosure. The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. Other substitutions, modifications, changes, and omissions may be made in the design, operating conditions and arrangement of the exemplary embodiments without departing from the scope of the present disclosure. 
         [0075]    Although the figures may show a specific order of method steps, the order of the steps may differ from what is depicted. Also two or more steps may be performed concurrently or with partial concurrence. All such variations are within the scope of the disclosure.