Abstract:
A viewed component of a vehicle instrument cluster includes a dial structure. A printed circuit board is arranged on the dial structure and has an outboard surface. A layer of printed ink is arranged on the outboard surface of the printed circuit board. A series of LEDs are arranged on the outboard surface of the printed circuit board wherein the series of LEDs occupy an outermost layer of the dial structure.

Description:
FIELD OF THE INVENTION 
   The present invention relates to instrument panel gauges in vehicles and more particularly to an instrument panel gauge having surface mounted light emitting diodes on an outer face. 
   BACKGROUND OF THE INVENTION 
   Instrument clusters on automobiles generally include a plurality of gauges for displaying such operational information such as vehicle speed, engine RPM, engine temperature, fuel level and many other information. The gauges may include analog or digital readings for displaying the information depending on manufacturer and styling preferences. An analog gauge typically includes a faceplate having indicia thereon such as numbers and a pointer for rotating to the appropriate number. 
   One important design consideration for an instrument cluster and related gauges is the ability of a vehicle operator to easily view and read the gauges in all driving environments. In particular, nighttime driving requires the instrument cluster to illuminate in some fashion whereby the numbers and corresponding pointers are easily distinguishable. 
   In one example, light emitting diodes (LEDs) have been used to backlight a gauge or accent a telltale or other icon on the instrument cluster. Typically, such LEDs are mounted inboard of a gauge face and are used in conjunction with a chimney structure mounted between the gauge face and the LED. As a result, the chimney is adapted to disperse the light outward from a face of the gauge. However, the use of inboard mounted LEDs and related chimneys may compromise packaging and limit the amount of LEDs that may be used on the gauge. 
   SUMMARY OF THE INVENTION 
   A viewed component of a vehicle instrument cluster includes a dial structure. A printed circuit board is arranged on the dial structure and has an outboard surface. A layer of printed ink is arranged on the outboard surface of the printed circuit board. A series of LEDs are arranged on the outboard surface of the printed circuit board wherein the series of LEDs occupy an outermost layer of the dial structure. 
   In one example, the layer of printed ink defines a series of indicia on the outboard face. The layer of printed ink further defines a plurality of gradations on the outboard face. 
   According to other features, the viewed component further comprises an electroluminescent lamp arranged inboard of the printed circuit board. 
   According to still additional features, an insulating material is arranged outboard of the printed circuit board. The series of LEDs are electrically connected to the printed circuit board through vias extending through the insulating material. 
   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 front illustration of a viewed component constructed in accordance with the present teachings; 
       FIG. 2  is a partial sectional view along line  2 - 2  of  FIG. 1 ; 
       FIG. 3  is a partial sectional view through a surface mounted LED of  FIG. 1  according to another embodiment; and 
       FIG. 4  is a partial sectional view through a surface mounted LED of  FIG. 1  according to still another embodiment. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
   With initial reference to  FIG. 1 , a viewed component constructed in accordance to the present teachings is shown and identified generally at reference  10 . The viewed component  10  is illustrated as a speedometer. It is appreciated that the viewed component may alternatively comprise other gauges, dials or instruments such as, but not limited to a tachometer, a fuel gauge, a temperature gauge and an oil pressure gauge for example. 
   With reference now to  FIGS. 1 and 2 , the viewed component  10  generally includes a housing  12 , a dial  16 , an outboard printed circuit board  20 , an inboard printed circuit board  22 , a first series of light emitting diodes (LEDs)  24 , a second series of LEDs  26  and a third series of LEDs  30 . The first and second series of LEDs  24  and  26  are surface mounted on an outboard surface  34  of the outboard printed circuit board  20 . Conductive traces  38  and  40  connect the respective first and second series of LEDs  24  and  26  to the outboard printed circuit board  20 . An electrical connector  42  extends between the outboard and inboard printed circuit board  20  and  22 . 
   The third series of LEDs  30  are arranged on the inboard printed circuit board  22 . A chimney  44  is arranged between the outboard and inboard printed circuit board  20  and  22  to direct light from the third series of LEDs  30  outward. A pointer  48  is centrally mounted for rotatable movement within the viewed component  10 . As will be described in greater detail, the first and second series of LEDs  24  and  26  are surface mounted on the outboard printed circuit board  20  for enhanced resolution. In addition, by surface mounting the first series of LEDs  24 , they may be placed closer together as compared to the third series of LEDs  30  that incorporate the chimney arrangement and require increased packaging space. 
   The dial  16  defines a face  50  on the outboard surface  34  of the outboard printed circuit board  20 . The face  50  includes a layer of printed ink  54 . The layer of printed ink  54  defines a first series of indicia  56  ( FIG. 1 ) thereon. While represented as numerical English units (MPH), the first series of indicia  56  may alternatively comprise other markers including Metric units, such as Km/h for example. In addition, the layer of printed ink  54  further defines a first series of gradations  60  arranged radially around the face  50  of the dial  16 . The printed ink  54  also defines a second series of indicia  66  arranged inboard of the first series of indicia  56 . While represented as Metric units (Km/h), the second series of indicia  66  may alternatively comprise other markers including English units such as MPH for example. 
   A second series of gradations  70  are aligned to correspond with the second series of indicia  66 . It is appreciated that the layout and content of the printed ink  54  is merely exemplary and that other arrangements may be used on the face  50  of the dial  16  according to design requirements. The first series of LEDs  24  may be additionally or alternatively located radially outboard of the pointer  48  such as adjacent to the first series of indicia  56 . Other locations are contemplated. Likewise, the second and third series of LEDs  26  and  30  may be configured to align with other printed identifiers on the dial  16  such as tell tales for example. 
   With reference now to  FIG. 3 , a sectional view of a viewed component  110  according to an additional embodiment is shown. The viewed component  110  incorporates a series of surface mounted LEDs  124  similar to the first series of LEDs  24  described in relation to the viewed component  10 . The viewed component  110  incorporates an electroluminescent (EL) lamp  130  inboard of a conductive trace  132  defining an outboard face  134 . In one form, the conductive trace  132  may be a printed circuit board. The conductive trace  132  may be semi-transparent or opaque such that the light emitted from the EL lamp  130  may pass outwardly therethrough. As shown, an LED  124  is electrically connected to the conductive trace  132 . A layer of printed ink  154  may be arranged across the face  134  of the conductive trace  132 . The printed ink  154  may define indicia, gradations or other markings as desired. Of note, the LED  124  defines an outboard plane on the viewed component  110 . 
   In one exemplary construction, the EL lamp  130  may comprise an outboard electrode  160  and an inboard electrode  162  sandwiching an electroluminescent material  166 . One exemplary material for the inboard and outboard electrodes  160  and  162  may be barium titanate. The electroluminescent material  166  may comprise phosphor, for example. A layer of transparent conductive material  170  and  172  is arranged on opposite sides of the electroluminescent material  166 . In one form, the transparent conductive material  170  and  172  may comprise Indium Tin Oxide (ITO). It is appreciated that the configuration and materials of the EL lamp  130  are merely exemplary and other configurations may be employed. 
   Turning now to  FIG. 4 , a sectional view of a viewed component  210  according to an additional embodiment is shown. The viewed component  210  incorporates an electroluminescent (EL) lamp  230  inboard of a conductive trace  232  defining an outboard face  234  similar to the viewed component  110  illustrated in  FIG. 3 . In one form, the conductive trace  232  may be a printed circuit board. The conductive trace  232  may be semi-transparent or opaque such that the light emitted from the EL lamp  230  may pass outwardly therethrough. A semi-transparent insulator  280  is arranged outboard of the conductive trace  232 . The semi-transparent insulator  280  provides increased protection and therefore durability to the EL lamp  230 . As shown, an LED  224  is electrically connected to the conductive trace  232  by way of vias  282 . The vias  282  each comprise electrically conducive material that extend through passages in the semi-transparent insulator  280 . A layer of printed ink  254  may be arranged across the insulator  280 . The printed ink  254  may define indicia, gradations or other markings as desired. Of note, the LED  224  defines an outboard plane on the viewed component  210 . 
   Returning now to  FIG. 1 , the surface mounted arrangement of the first series of LEDs  24  allows a large number of LEDs  24  to be located adjacent each other. Of note, the first series of LEDs  24  occupy on outermost layer of the dial  16 . In one example, the first series of LEDs  24  may be configured to illuminate in a pattern corresponding to the travel of the pointer  48 . For example, if the pointer  48  is rotated to point to 40 MPH, each LED  24  of the first series located at 40 MPH and at MPH locations below 40 MPH would be illuminated. As a result, the corresponding LEDs  24  create a three-dimensional radial line for the operator to view. It is contemplated that the first series of LEDs  24  may be located elsewhere on the dial  16  and/or configured to illuminate differently. For example, the first series of LEDs  24  may be located proximate the first series of indicia  60 . In another example, the first series of LEDs  24  may be configured to illuminate only at the corresponding pointer location. 
   Those skilled in the art can now appreciate from the foregoing description that the broad teachings of the present invention can be implemented in a variety of forms. For example, as noted, “EL” stands for electroluminescent. As such, the light source may be a surface mounted device such as an LED, a deposited (printed) polymer encapsulated electro-luminescent device or other device. Therefore, while this invention has been described in connection with particular examples thereof, the true scope of the invention should not be so limited since other modifications will become apparent to the skilled practitioner upon a study of the drawings, the specification and the following claims.