Abstract:
An exterior rearview mirror assembly for a motor vehicle includes a mounting bracket securable to a lateral side of a vehicle. A mirror case is secured to the mirror bracket. A primary reflector is fixedly secured to the primary portion of the backing plate. The primary reflector defines a primary field of view extending laterally away from the lateral side of the motor vehicle. A secondary reflector defines a secondary field of view extending laterally in space disposed adjacent the lateral side of the motor vehicle, wherein the secondary field of view overlaps the primary field of view in a range of 20% to 80%. The field of view of the secondary reflector is also directed downwardly with respect to the field of view of the primary reflector.

Description:
[0001]    This patent application claims priority to a U.S. provisional patent application having Ser. No. 61/148,404, which is hereby incorporated by reference. 
     
    
     BACKGROUND ART 
       [0002]    1. Field of the Invention 
         [0003]    The invention relates to exterior rearview mirror assembly assemblies for motor vehicles. More particularly, the invention relates to exterior rearview mirror assembly assemblies that incorporate primary and secondary reflectors to increase the overall viewing area provided by the exterior rearview mirror assembly. 
         [0004]    2. Description of the Related Art 
         [0005]    Secondary reflectors on exterior rearview mirror assemblies are commonly referred to as blind spot mirrors. In such exterior rearview mirror assemblies, a primary reflector is known as the Main Viewing Glass and the secondary reflector also know as a Blind Spot Mirror. Automotive manufacturers often provide blind spot mirrors on the vehicle they sell because it is well known that a ‘blind zone’ (or blind spot) exists immediately adjacent the lateral sides of the vehicle. This blind zone is the area that starts where the field of view of the primary reflector ends and continues to the point where the driver can see the object through his or her peripheral vision. By providing this secondary reflector, automotive manufacturers reduce or eliminate this ‘blind zone.’ 
         [0006]    In some cases, this secondary reflector is mounted separately from the primary reflector and thus is independently adjustable therefrom. With this configuration, adjusting the secondary reflector to a position that provides a satisfactory field of view becomes an easy matter and does not impact the driver&#39;s preference on the positioning of the primary reflector. However, in other cases, the secondary reflector is mounted on the same backing plate, or carrier, as the primary reflector. Is such designs, the secondary reflector is not independently adjustable from the primary reflector. Therefore, after the driver adjusts the exterior mirror such that the primary reflector is in the desired position, the field of view of the secondary reflector is fixed and cannot be adjusted. In numerous production models that exist, there is dissatisfaction in the positioning of this secondary reflector. 
         [0007]    The nominal position of the primary reflector is determined by those skilled in the art and the means to determine this are well known within the industry. Federal Regulations provide guidelines in this process and the end result must meet these regulations. However, determining the nominal position for a secondary reflector is not regulated and attempts at orienting the secondary reflector vis-à-vis the primary reflector have been made that resulted in less than satisfactory results. 
       SUMMARY OF THE INVENTION 
       [0008]    An exterior rearview mirror assembly is mounted to a motor vehicle having a forward end, a back end and a lateral side. The exterior rearview mirror assembly includes a mounting bracket fixedly securable to a lateral side of the motor vehicle. A mirror case is secured to the mirror bracket. The mirror case defines a housing having a closed side facing the forward end of the motor vehicle and a primary opening facing the back end. A backing plate is movably secured within the mirror case. The backing plate includes a primary portion and a secondary portion. A primary reflector is fixedly secured to the primary portion of the backing plate. The primary reflector defines a primary field of view extending laterally away from the lateral side of the motor vehicle. A secondary reflector is fixedly secured to the secondary portion of the backing plate. The secondary reflector defines a secondary field of view extending laterally in space disposed adjacent the lateral side of the motor vehicle, wherein the secondary field of view overlaps the primary field of view in a range of 20% to 80%. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    Advantages of the 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: 
           [0010]      FIG. 1  is a perspective view of one embodiment of the invention; 
           [0011]      FIG. 2  is a top view of a motor vehicle, partially cut away, incorporating the invention, wherein the drawing includes lines representing various lines of sight; 
           [0012]      FIG. 3  is a top view of a motor vehicle, partially cut away, incorporating the invention, and another vehicle positioned with respect to the motor vehicle, wherein the drawing includes lines representing various lines of sight; 
           [0013]      FIG. 4  is a side view of an operator of a motor vehicle with line of sight lines between the operator and the invention; and 
           [0014]      FIG. 5  is a side view of a motor vehicle incorporating the invention, and another vehicle positioned with respect to the motor vehicle, wherein the drawing includes lines representing various lines of sight. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0015]    Referring now to the drawings,  FIG. 1  shows the detail of an exterior rearview mirror assembly  10  incorporating the invention. The exterior rearview mirror assembly  10  includes a mounting bracket  12  that secures the exterior rearview mirror assembly  10  to a lateral side  14  of a motor vehicle  16 . The motor vehicle  16  defines a forward end  18  and a back end  20 . The motor vehicle  16  includes a second lateral side (not shown), typically with a passenger side exterior rearview mirror assembly secured thereto. While the passenger side exterior rearview mirror assembly typically would not include the invention, it may if it were so designed. 
         [0016]    A mirror case or housing, generally indicated at  22 , is secured to the mounting bracket  12 . The mirror case  22  defines a primary opening  24  that faces rearward with respect to the forward motion of the motor vehicle  16 . The mirror case  22  includes a forward face  26  that wraps around the primary opening  24  to create a mirror frame  28  disposed around the primary opening  24 . A primary reflector  30  and a secondary reflector  32  are visible through the primary opening  24 . A bridge  34  between the primary  30  and secondary  32  reflectors helps distinguish the border shared therebetween. However, a bridge may not always be present. It should be appreciated by those skilled in the art that the exterior rearview mirror assembly  10  may include fewer or more features, depending on the design and package choices and those features do not add or detract from the inventive method. 
         [0017]    The primary  30  and secondary  32  reflectors are mounted to a backing plate  36 . It is understood that the backing plate  36  is movably secured to the exterior rearview mirror assembly  10 . In the preferred embodiment, there is no need for a second backing plate for the secondary reflector  32 .  FIGS. 2 and 3  show the plan view and the side view respectively of the design elements of the invention. 
         [0018]    The primary reflector  30  may be flat or convex. The secondary reflector  32  is highly convex and provides a greater field of view than the primary reflector  30 . For the remainder of the discussion, the backing plate  36 , and, hence, the primary reflector  30  and the secondary reflector  32  are fixed in a predetermined orientation for purposes of determining the respective fields of view for the two reflectors  30 ,  32 . This fixed position is commonly called the “Design Nominal Position.” 
         [0019]      FIGS. 2 and 3  may be looked at concurrently as  FIG. 2  is an enlarged view of the detail that is not easily discernable within  FIG. 3 . In  FIGS. 2 and 3 , a pair of ellipses  38 ,  40  defines locations relating to or representing where 95% of the eyes of all drivers are with respect to the exterior rearview mirror assembly  10 . Eye points  42 ,  44  are defined within the eye ellipses  38 ,  40 . In this Figure, the eye points  42 ,  44  have been rotated about a neck point  46  to look at the view in the exterior rearview mirror assembly  10 . From eye points  42 ,  44 , lines of sight  48 ,  50 ,  52 ,  54  extend outward toward the primary reflector  30  and the secondary reflector  32 . In particular, the line of sight  48  extends from eye point  42  to an inboard edge  56  of the primary reflector  30  and that line of sight  48  is reflected rearward and represented by line of sight  58 , which is also referred to as the inboard boundary of the field of view for the primary reflector  30 . The line of sight  50  extends from the eye point  44  to an outboard edge  60  of the primary reflector  30  and that line of sight is reflected rearward and represented by a line of sight  62 , which is referred to as the outboard boundary of the field of view for the primary reflector  30 . Thus, the primary field of view  64  for the primary reflector  30  is defined can be represented by the angle between the boundaries represented by lines of sight  58 ,  62 . 
         [0020]    Similarly, a line of sight  66  extends between the eye point  42  and an inboard edge of the secondary reflector  32  and that line of sight  66  is reflected rearward and shown as a line of sight  70 , which is referred to as the inboard boundary of the field of view for the secondary reflector  32 . The line of sight  54  extends from the eye point  44  to an outboard edge  72  of the secondary reflector  32 , and that line of sight is reflected rearward and shown as a line of sight  76 , which is referred to as the outboard boundary of the field of view for the secondary reflector  32 . Thus, the secondary field of view  76  for the secondary reflector  32  can be represented by the angle between boundaries represented by lines of sight  70 ,  76 . It will also be in  FIG. 2  that line of sight  66  that reflects off the inboard edge  68  of the secondary reflector  32  goes generally rearward providing a view of vehicles  80  traveling in a passing lane  82  adjacent to the motor vehicle  16  being driven. This passing lane  82  adjacent is generally shown in  FIG. 2  by its centerline  84 . The centerline  84  is defined as being a distance of  12  feet from a centerline  86  of a lane  88  in which the motor vehicle  16  is traveling. The field of view  78  provided by the secondary reflector  32  extends significantly far behind the driven motor vehicle  16  and it has also been determined that a driver  79  of the driven motor vehicle  16  will be able to achieve a reference of the vehicle  80  traveling in the passing lane  82  because the driver  79  will be able to see the passing vehicle  80  within the primary field of view  64  of the primary reflector  30  and concurrently see the same passing vehicle  80  within the secondary field of view  78  of the secondary reflector  32 . 
         [0021]    Also shown in  FIGS. 2 and 3  is a line  90  representing outer bounds of the peripheral vision of the driver  79 . For the purposes of this drawing, the peripheral vision line  90  has been established at an angle 75 degrees from the driver&#39;s forward view. Another way of describing the peripheral vision boundary line  90  is that it is 15 degrees from a line drawn which bisects the two eye points  42 ,  44 . Those skilled in the art will realize that the average person has more than 75 degrees of peripheral vision; however, 75 degrees of peripheral vision allows for a safety margin. 
         [0022]    The passing vehicle  80  is shown to be a motorcycle that is seven feet long. This represents perhaps the smallest and shortest motorized vehicle that may be present on a two lane road or highway. This small passing vehicle  80  is still viewable within the field of view of the secondary reflector  32  as it is entering into the peripheral view  90  of the driver  79 , thus eliminating the blind spot or zone. 
         [0023]    Stating it another way, with this given set of parameters, the driver  79 , when looking at the reflection in the secondary reflector  32  will be able to see the vehicle  80  in the adjacent lane  84  in both his primary reflector  30  and his secondary reflector  32  for an extended period of time providing a reference in the mind of the driver  79  to establish the relative position of the passing vehicle  80 . As the vehicle  80  continues to pass the driven vehicle  16 , at the critical point the driver  79  is able to see the passing vehicle  80  in both the secondary reflector  32  and through his peripheral vision because a portion of the passing vehicle  80  has crossed the boundary  90  defining where the peripheral vision of the driver  79  starts. 
         [0024]      FIGS. 4 and 5  may be looked at concurrently as  FIG. 4  is a close up view of the detail that is not easily discernable within  FIG. 5 .  FIGS. 4 and 5  show the side view of driven vehicle  16  and the resultant lines of sight from a determined point within the eye ellipse  38 ,  40  to the primary reflector  30  and the secondary reflector  32  and how they are reflected rearward. For clarity and the purposes of this discussion, an eye ellipse  92  shown in  FIG. 2  is an average of the two eye ellipses  38 ,  40  discussed above. Also, an eye point  94  is an average of eye points  42 ,  44 . Returning back to  FIGS. 4 and 5 , it is seen that a line of sight  96  extends from eye point  94  to an upper edge  98  of the secondary reflector  32 . This line of sight is reflected rearward and shown as a line of sight  100 . A line of sight  102  extends from the eye point  94  to a lower edge  104  of the secondary reflector  32 , and that line of sight is reflected rearward and shown as a line of sight  106 . These reflected lines of sight  100 ,  106  define a secondary side field of view  108  for the secondary reflector  32  and is represented by the angle between the reflected lines of sight  100 ,  106 . It will also be seen that that a line of sight  110  extends from the eye point  94  to a center  112  of the secondary reflector  32  and that line of sight  112  is reflected rearward and shown as a center reflected line of sight  114 , which can also be defined as the field of view center line  114  for the secondary reflector  32 . 
         [0025]      FIGS. 4 and 5  also shows line of sight  116  extends from eye point  94  to an approximate center  118  of the primary reflector  30  and that line of sight is reflected rearward and shown as a reflected line of sight  120 , which can also be defined as the field of view center line for the primary reflector  30 . An angle  122  is defined by the difference in direction (aiming) from the reflected line of sight  114  of the secondary reflector  32  and reflected line of sight  120  of the primary reflector  30 . 
         [0026]    It can be seen that the reflected line of sight  120  points somewhat downward due to Government Regulations. However, those skilled in the art will realize that the average driver  79  tends to adjust his primary reflector  30  such that the center of his field of view tends to point at the horizon line. The extent to which the driver  79  make this adjustment tends to be more for taller vehicles and less for shorter vehicles. Those skilled in the art will also know that the degree with which the reflected line of sight  120  points downward is greater for taller vehicles than it is for shorter vehicles. For this reason, the secondary reflector  32  is positioned or aimed such that field of view centerline  114  of the secondary reflector  32  is below the field of view center line  120  of the primary reflector  30  by the amount of angle  122 . This angle is typically 5 degrees but can be defined as a range of 3 to 7 degrees. 
         [0027]    If the secondary reflector  32  were aimed at a target while the backing plate  36  is held in the design nominal position, adjusting the mirror upward as is typically done (and defined above) would result in the secondary reflector  32  no longer able to clearly see the preferred target which would result in customer dissatisfaction. 
         [0028]    The invention has been described in an illustrative manner. It is to be understood that the terminology, which has been used, is intended to be in the nature of words of description rather than of limitation. 
         [0029]    Many modifications and variations of the invention are possible in light of the above teachings. Therefore, within the scope of the appended claims, the invention may be practiced other than as specifically described.