Abstract:
A gauge assembly which has a gauge surface including graphics representing a vehicle operating parameter. A pointer arm is provided which is made out of a light guide or light transmitting material. The pointer arm includes a step portion in an operative portion of the second bottom surface for reducing light received by said second surface adjacent the step portion and providing an overall even light throughout the operative illuminated viewing surface of the pointer arm.

Description:
FIELD OF THE INVENTION 
     The present invention relates to vehicle instrument panels and clusters, and more specifically to a pointer for a gauge that includes features providing improved illumination characteristics. 
     BACKGROUND OF THE INVENTION 
     Vehicles include instrument panels to communicate information indicative of operation to an operator. Motor vehicles include instrument panels with several gauges and dials that communicate vehicle conditions such as speed, engine rpm, temperature, oil pressure along with many other operational parameters. A pointer is typically provided that rotates about a fixed axis that points to value on the gauge face to communicate current values of an operational parameter. Pointers are often illuminated to further enhance visibility and appearance. Light sources that direct light along the axis or rotation can cause a bright spot at the axis on the pointer. 
     The geometry of the pointer including relative angles and widths between surfaces of the pointer provide a means of uniformly propagating light from a hub to a pointer tip. The size and shape of a pointer is limited by manufacturing practicalities such as possible mold draft angles. As an example, a solution to this problem is taught in my co-pending, commonly assigned Patent Application No.US2014/0165904A1 (incorporated herein by reference hereto). While this effectively solves the problem by using a reverse slope on the bottom of the pointer near the axis of the pointer and this provides substantially uniform illumination, the reverse slope type arm has proven troublesome in manufacturing. 
     Accordingly, it is desirable to design and develop a pointer that provides uniform illumination within manufacturing capabilities that increases an area in which luminance may be evenly distributed. 
     SUMMARY OF THE INVENTION 
     The subject invention provides a gauge assembly which has a gauge surface including graphics representing a vehicle operating parameter. A pointer is provided which is made out of a light guide or light transmitting material. The pointer is supported for movement about an axis to indicate a current condition of the vehicle operating parameter by pointing to a specific location on the gauge surface. The pointer has a pointer arm extending away from a hub of the gauge assembly. An illumination source is provided for illuminating the pointer arm. The pointer arm includes a reflecting surface at a portion on a first end of the pointer opposite a pointing end. The reflecting surface reflects light received from the illuminating source into the length of said pointer arm. The pointer arm also includes a first illuminated viewing surface and a second bottom surface to which light from said reflecting surface is at least partially reflected toward the illuminated viewing surface. The second surface including a step portion in an operative portion of the second surface for reducing light received by said second surface adjacent the step portion and providing an overall even light throughout the operative illuminated viewing surface. 
     The step portion in the second surface generates a substantially uniform luminance over a larger area and pointer length by reducing a portion of the reflected light to the second surface. The step portion also allows a closer radius of useful pointer light in the gauge. 
     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
         FIG. 1  is a schematic view of an example instrument panel for a motor vehicle. 
         FIG. 2  is a side view of a pointer arm made in accordance with the present invention. 
         FIG. 3  is a cross-section of an example pointer assembly showing the arm of  FIG. 2  in the operating environment of a gauge assembly. 
         FIG. 4  is an enlarged cross-section of the pointer assembly of  FIG. 2 . 
         FIG. 5  is a bottom view of a pointer arm of  FIG. 2 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following description of the preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
     Referring now to  FIG. 1 , there is provided a dashboard generally shown at  10  for a motor vehicle. The dashboard  10  includes an instrument panel  12  that includes a plurality of gauges  14  and dials  16 . The gauges  14  communicate information indicative of vehicle operating parameters to vehicle operator. A pointer assembly generally indicated at  18  is included for the gauge  14  that rotates about an axis A-A to point to a specific portion of the graphics provided in each of the gauges  14  to indicate a current value of an operating condition. 
     Referring now to  FIG. 3 , gauge assembly  14  includes a housing  20  that supports a gauge surface  22  with graphics  24 . A printed circuit board  26  supports a stepper motor  28  that drives a shaft  30 . The shaft  30  maybe a clear shaft or a shaft including a central opening through which light may propagate upwardly into the pointer assembly  18 . 
     A shroud  32  is supported on the shaft  30 . A light source  34  is supported on the printed circuit board  26  along an axis A-A. The light source  34  propagates light upward into the pointer assembly  18  along the axis A-A. Other light sources  36  may optionally be provided on the printed circuit board  26  if desired for a particular application as will be appreciated by those skilled in the art. The light source  34  along the axis A may be utilized to direct light along the axis A-A. The light sources  36  may also be utilized that are disposed around the axis A-A within the light housing  38  to direct light upward into the pointer assembly  18 , if required depending on the final design of the gauge  14 . 
     The pointer assembly  18  includes a pointer  40  that includes a base  42  disposed about the axis A-A and arm portion  44 . In a preferred embodiment, the shaft  30  is clear such that shaft  30  will also propagate light from the light source  34  upward into the pointer  40 . In a preferred embodiment, the light source  34  is a light emitting diode, however, other light sources as are known by those skilled in the art are also used in the present invention. 
     The pointer  40  includes a first illuminated viewing surface  44 , a second bottom surface  46  and an angled reflecting surface  48 . The reflecting surface  48  for reflects light received from illuminating source  34  into the length of said pointer arm  18 . 
     A step portion generally shown at  50  is provided on the bottom of the pointer and adjacent to second bottom surface  46  which extends from the second bottom surface  46  toward the first illuminated surface  44  and which interferes at least in part with the reflected light path from the reflecting surface  48  to the second surface  46 . This is shown best in  FIG. 4 , wherein the light reflected L 1  is substantially attenuated by first step surface  52  and second step surface  54  which produces a light diminished area  56  along the surface  46 . Thus, the step portion  50  includes a first step surface  52  which is substantially normal to an axis of rotation (A-A) of said pointer and a second angled surface  54  at an angle ‘c’ of about 90 degrees to said first surface  52 . While in a preferred embodiment, the second surface is at an angle of about 90 degrees, it will be readily appreciated that the surface can be used at any angle which effectively blocks or reduces at least a portion of the light to a “shaded” portion  56  of the pointer arm  14  along the second bottom surface  46 . The shaded portion  56  may be generally from about 1% to about 85% and typically 5% to about 60% with a preferred range of 10% to about 40% of the length of the surface  46  depending on the design configurations of the pointer and the desired result. In any case, this step arrangement reduces the propensity for there to be a “hot” spot of light near the axis A-A in the visible illuminated surface  44 . This allows the lighting along the pointer  14  to be consistent. It is readily appreciated that the angle ‘b’ between the surface  54  and surface  46  is positive and less than 90 degrees. As stated above, in a preferred embodiment, the bottom surface tapers toward the line B-B normal to the rotation of the pointer  14 . 
     It should be readily appreciated that the pointer and be used independently in a gauge in many mounted configurations without deviating from the scope or the present invention. However, in a typical embodiment, an optional cap  58  is disposed over the base  42  of the pointer  40  eliminate a possible viewable bright spot of the pointer  40 . The cap  58  includes an arm portion  60  that extends toward the tip  62 . A counterweight  64  is supported by the shroud  32  under the cap  58 . The shroud  32  includes a shroud stem  66  that includes a central opening  68  along the axis A-A that receives the shaft  30 . The pointer arm  24  includes a first width  70  disposed near the base and tapers to a second width  72  near the tip  36  and a first height  74  which tapers to a second height  76  near the tip  62 . 
     As will be readily appreciated by those practicing the present invention, the stepped portion of the pointer of the present invention substantially provides a uniform luminance in pointers that include large differences in thickness between the hub and tip and may be adapted to other designs as well where eliminating a portion of the light near the axis of the pointer is desired. 
     The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the essence of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.