Abstract:
A gauge with indicating pointer has three light sources on a printed circuit board. A rear dial plate has rear markings such as MPH indicia. The first light source illuminates the pointer length, which points to the rear indicia. The second light source illuminates a front dial assembly located on an opposite side of the indicator as the rear dial plate by passing light through the thickness of the indicator. The front dial assembly is cantilevered over the rotating pointer to permit pointer rotation. The third light source illuminates the rear indicia. The front dial assembly has a front dial plate with front indicia illuminated by the second light source and to which the pointer points. The three light sources may be different colors since each illuminates a specific area of the gauge. The front dial assembly may display a separate lighted scale, such as KPH from the rear markings.

Description:
FIELD 
       [0001]    The present disclosure relates to a vehicle gauge and light guide structure. More specifically, the disclosure relates to a light guide structure with an indicator that is capable of passing light through its thickness to provide light to a dial in front of the pointer. 
       BACKGROUND 
       [0002]    The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. A conventional vehicle gauge, such as a speedometer gauge, typically has a light source positioned on a printed circuit board (“PCB”) to direct light to the gauge face or through the gauge face to make any indicia, such as numbers, visible to a person viewing the gauge. Additionally, gauges known in the art may have a pointer that is illuminated when light is directed through the pointer length from one end of the pointer. 
         [0003]    While current vehicle gauges have generally proven to be satisfactory for their applications, each is associated with its share of limitations. One limitation of current gauges is that light can not be directed onto a second gauge face in front of the pointer using a light source behind the pointer. Another limitation of current gauges is that light can not be passed to a second gauge face in front of the pointer using current gauge structures, such as a single PCB. Still yet another limitation is that projecting light to a gauge face in front of a pointer traditionally requires wiring or electrical leads in front of the pointer, which may limit gauge function, such as pointer rotation sweep angle. Finally, current pointers do not permit light to pass through their thicknesses, so that such light may be further used in other areas of the gauge. 
         [0004]    What is needed then is a device that does not suffer from the above limitations. This, in turn, will provide a device that permits a second gauge face in front of a gauge pointer to be illuminated but that does not require a printed circuit board or wiring in front of the pointer to illuminate the second face. Additionally, a device will be provided with a face in front of the pointer that does not interfere with pointer rotation operation. Finally, a device will be provided that has a gauge face in front of the pointer that permits indicia to be illuminated with a different color as the main or rear scale indicia and different from the pointer. 
       SUMMARY 
       [0005]    An indicating instrument employs a pointer that rotates in front of a rear gauge face and behind a front gauge face to measure or indicated a quantity such as vehicle speed. A printed circuit board may have three separate light sources situated on it; for instance, a main, or rear, dial plate has rear indicia illuminated by a first light source, a pointer may be illuminated by a second light source, and front indicia on a front dial face may be illuminated by a third light source. A pointer capable of rotating may be positioned in front of the rear dial plate to point to the rear indicia as the measured quantity changes, yet remain behind the front dial plate to point to the front indicia. 
         [0006]    Light from the first light source may be directed lengthwise through the pointer indicator to illuminate the indicator. The front dial plate, which may be part of a separate front dial assembly, located on an opposite side of the indicator as the rear dial plate, may be cantilevered over the pointer instrument to permit free rotational movement of the pointer. The second light source may provide illumination to the front dial assembly as light from the second light source is directed through a thickness of the rotating indicator before passing into the front dial assembly. A third light source on the printed circuit board illuminates the rear indicia. Because the light from each of the three light sources do not mix or interfere with each other, the three light sources may each be different colors for an overall aesthetically pleasing appearance. 
         [0007]    The front dial assembly may further utilize an outer ring, an inner ring, and a front dial plate that are illuminated by the second light source and a non-illuminated separator ring, which provides contrast when positioned between the outer ring and the inner ring. The front dial plate may possess indicia that correspond to possible pointer positions, such as kilometer per hour (KPH) markings while the rear plate indicia may indicate miles per hour (MPH) markings. A third light source illuminates the rear indicia. 
     
    
     
       DRAWINGS 
         [0008]    The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
           [0009]      FIG. 1  is an exploded view of a gauge structure; 
           [0010]      FIG. 2  is a side view of the gauge structure of  FIG. 1 ; 
           [0011]      FIG. 3  is an enlarged side view of a gauge structure of  FIG. 2 ; 
           [0012]      FIG. 4  is an enlarged cross-sectional view of the gauge structure taken about the line  4 - 4  of  FIG. 6 ; 
           [0013]      FIG. 5  is an enlarged partial exploded view of the gauge structure of  FIG. 1 ; and 
           [0014]      FIG. 6  is a front view of a gauge structure depicting an attachment location of an auxiliary face. 
       
    
    
     DETAILED DESCRIPTION 
       [0015]    The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. Throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. 
         [0016]    Turning now to  FIG. 1 , an exploded view of a gauge  10  is depicted. More specifically, the gauge  10  is an assembly of various parts such as, but not limited to, a printed circuit board  12  (“PCB”) and groupings of light emitting diodes  14 ,  16 ,  18  (“LED”). A first plurality of light emitting diodes  14 , a second plurality of light emitting diodes  16 , and a third plurality light emitting diodes  18  provide the necessary light to the rear indicia  20  and front indicia  22 . The rear indicia  20  may represent vehicle speeds measured in miles per hour (MPH), as on a speedometer, that a vehicle may undergo as it is driven. As a second, separate scale, the front indicia  22  may represent a different vehicle speed scale, such as kilometers per hour (KPH). Indicating both scale on the same gauge is convenient for drivers who, for instance, drive in the United States and Canada on a regular basis and require both scales. The same indicating instrument, or pointer  30 , may be used to indicate the speed on both scales at the same time. 
         [0017]    Continuing with  FIG. 1  from the PCB  12 , major components of the indicating instrument or gauge  10  are a cup  24  surrounded by a housing  26 , the housing  26  covered by a forming dial  28  on one side. The forming dial  28  has indicia  20 , which denote miles per hour (MPH) for example, etched or molded into it to provide markings to which a pointer  30  points as the pointer  30  rotates about the forming dial  28 . The pointer  30  may also be referred to as an indicating instrument, or simply an indicator. The forming dial  28 , cup  24 , and housing  26  mount onto the PCB  12  using locator pins  27  that reside in locator holes  29 ,  33  and at least one fastener  32 . With the installation of the pointer hub  34  over the forming dial  28  and housing  26 , the forming dial  28  and first set of indicia  20  can be described as being behind the pointer  30 . The pointer hub  34  fits over the pointer  30 , yet a center section of the pointer hub  34  permits one to see the illuminated pointer  30 . 
         [0018]    Continuing with  FIG. 1 , an outer ring  36  has an outer ring land  38 . The outer ring  36  with outer ring land  38  is attached to an outer ring post  40 , which attaches to the assembly of the forming dial  28 , housing  26 , cup  24 , and PCB  12  via the at least one fastener  32 . Fitting over and into the outer ring  36  is a separator disk  42 , which also has a land  44 . Next, an inner ring  46  with an inner ring land  48  fits over and into the separator disk  42 . An inner or front dial  50  with front indicia  22  fits over and into the inner ring  46 . The entire assemblage is then encapsulated with the gauge housing  52 , which has its frontal area covered by a gauge housing cover  54 . 
         [0019]      FIG. 2  depicts a side view of the gauge structure  10  of  FIG. 1 . More specifically, the front dial assembly  56  or center ring assembly is depicted in front of the pointer  30 , as opposed to the forming dial  28 , which is located behind the pointer  30 . Now, with additional reference to  FIGS. 3-6 , more detailed operation of the gauge  10  and its LED lighting will be explained. Turning to  FIG. 3 , the LEDs  14 ,  16  and  18  are depicted resident on the PCB  12 . A number of LEDs  14  provide light to the pointer  30 . More specifically, the light beam  58  from LED  14  projects into the pointer  30  and is reflected from the chamfer  60  so that light is projected throughout the longitudinal length of the pointer  30 . In this manner, only the pointer  30  is illuminated by the color of the LED  14 . The LEDs  14  provide consistent and steady light to the pointer  30  even as the pointer  30  rotates about the face of the forming dial  28 . Such lighting is possible because the LEDs  14  are arranged in a circular pattern, as is depicted in  FIG. 1 . The LEDs  14 , although arranged in a circular pattern, stop short of a complete 360 degree arrangement because of the outer ring post  40  ( FIGS. 1 and 4 ) which secures the outer ring  36  to the PCB  12 . Indicia  20  are lit by LEDs  18  that are positioned about the PCB  12 . The pointer motor  62  and associated shaft  64 , drives the pointer  30 . 
         [0020]      FIGS. 1-3  also depict LEDs  16  which supply light to the front dial assembly  56 . More specifically,  FIG. 3  depicts how the pointer  30  not only passes light longitudinally through the pointer  30  length, but also through its thickness, which is perpendicular to the longitudinal length of the pointer  30 . More specifically, LED  16  generates multiple light beams  66 ,  68 . From LED  16 , light beam  66  is directed into the outer ring  36 , where it reflects from chamfer  66  and is directed through the outer ring  36  to the land  38 , which is visible to an observer, such as a vehicle driver. Thus, the outer ring land  38  appears as a light ring to an observer as the light exits the land  38 . Similarly, LED  16  also emits light beam  68  into the inner ring  46 . More specifically, the light beam  68  enters the inner ring  46  and is reflected by chamfer  68 , which directs the light beam through the inner ring  46  where it exits at the inner ring land  48 . Because the light exits the inner ring land  48 , the light, in the shape of a circular ring, is visible to an observer. The front or inner dial  50  also transmits light from the front indicia  22  in the front dial  50 . 
         [0021]    Regarding materials of particular parts of the gauge  10 , the outer ring  36  may be made of the transparent plastic polymethyl methacrylate (PMMA), the separator ring  42  may be made of Acrylonitrile Butadiene Styrene (ABS), the inner ring  46  may be made of the transparent plastic polymethyl methacrylate (PMMA) and the inner dial  50  may be made of polycarbonate (PC) sheet. However, the structure of the present teachings is not limited to such, and as a result, structural portions that must transmit light from the LEDs, may be made of any suitable lightweight plastic. 
         [0022]    Continuing with  FIG. 4 , which is an enlarged cross-sectional view of the gauge structure taken about the line  4 - 4  of  FIG. 6 , a separator disk  42  resides between the outer ring  36  and the inner ring  46 . In the present teachings, the separator disk  42  is not a light transmitting part, and therefore, light does not pass through the separator disk  42 . However, the separator disk  42  has a separator disk land  44 , which provides a non-illuminated ring of contrast between the light emitting outer ring land  38  and the light emitting inner ring land  48  when viewed by an observer. Continuing,  FIG. 4  depicts the outer ring post  40  that supports the cantilevered front dial assembly  56 . As depicted the outer ring post  40  with front dial assembly  56  mounts above the printed circuit board  12  via fastener  32  through fastener hole  69  and forms a cantilevered structure of the front dial assembly  56  over the pointer  30  and pointer hub  34 . 
         [0023]      FIG. 5  is an enlarged partial exploded view of the gauge structure of  FIG. 1  and more clearly depicts the outer ring land  38  of the outer ring  36 , the separator disk land  44  of the separator disk  42 , and the inner ring land  48  of the inner ring.  FIG. 5  also depicts the front or inner dial  50  with front indicia  22 . The outer ring  36 , separator disk  42 , inner ring  46 , and inner dial  50  may be assembled by press fitting the parts together, such as in an interference type of fit. Additionally, parts  36 ,  42 ,  46  and  50  may be glued together using a clear adhesive. 
         [0024]      FIG. 6  is a front view of the gauge structure depicting an attachment location of the front dial assembly  56 . More specifically, the fastening location  70  of the outer ring post  40  is depicted in an area where the pointer  30  does not rotate due to interference of the post  40  and also the fastener  32  ( FIG. 1 ) that passes through the fastener hole  69 . As depicted, the pointer  30  may rotate clockwise from indicia  72  to indicia  74 . The teachings of the invention permit the indicia  20  of the forming dial  28  and the indicia  22  of the inner dial  50  to be illuminated by light sources on a single PCB  12 . Furthermore, as depicted in  FIGS. 1 and 6 , even though the pointer lies between the front dial assembly  56  and the forming dial  28 , the center, lighted portion of the pointer  30  is visible to an observer. The pointer hub  34  is not illuminated, and therefore the center portion of the hub  34  reveals the illuminated portion of the pointer  30  from LEDs  16 . 
         [0025]    There are multiple advantages resulting from the teachings of the present invention. First, the pointer  30  permits light to pass through its elongated portion and also through its thickness, which is generally perpendicular to its longitudinal portion. As light passes through its thickness, the light reaches a second dial structure  56  on the opposite side of the pointer  30  as a first dial structure  28 . With light at the second dial structure  56 , front indicia  22  may be illuminated. An advantage of light gaining access to a second dial  56  and illuminating portions of the second dial  56  is that the second dial structure  56  does not need to have its own printed circuit board with one or more LEDs, nor do wires or circuitry need to be routed to the second dial structure  56  from the printed circuit board  12  of the first dial structure  28 . A second advantage of the lighted indicia  22  on the front dial assembly  56  is that a second scale, such as numbers representing kilometers per hour (KPH) or other speed related data, may be indicated along with say, miles per hour (MPH) indicated by indicia  20 . 
         [0026]    The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist 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.