Flood lit cluster

An example light guide assembly for illuminating a display of an instrument cluster includes a light receiving portion, a light propagating portion and a reflective surface between the light receiving portion and the light propagating portion. The light receiving portion extends along a first axis, and the light propagating portion extends along a second axis which is transverse to the first axis. The reflective surface includes a stepped surface transverse to the reflective surface.

BACKGROUND OF THE INVENTION

The present invention relates to a vehicle instrument cluster, and more particularly to a light guide assembly for an illuminated display.

An instrument cluster of a vehicle is traditionally located on a vehicle dashboard and includes several displays or dials that indicate various vehicle operating conditions. For example, an instrument cluster may include a speedometer, a tachometer, an engine condition indicator, and other known types of gauges. These gauges are illuminated to facilitate reading of information by the vehicle occupant.

Instrument clusters include a printed circuit board (PCB) with electronic components for controlling operation of the instrument clusters. Light sources, such as light emitting diodes (LEDs), are typically mounted to the PCB. A light housing is used to contain the light produced by the light sources inside the instrument cluster and prevent unwanted light leakage. The instrument cluster further includes a display or dial on which the graphical image is formed or mounted.

The instrument cluster may include a light guide formed as a piece of clear material which channels the light received from the light source and redistributes the light over the display. In addition, light guides are known which are utilized to simultaneously illuminate the display and a pointer, which is moveable relative to the display to indicate the current status of the vehicle operating condition.

Disadvantageously, known light guides have not satisfactorily provided proper illumination of both the pointer and the display. The distribution of the light through the pointer and over the display often lacks uniformity. A shortage of light for illuminating the pointer may occur because a disproportional amount of light is reflected within the light guide to illuminate the display. Therefore, an increased number of light sources may be required to provide the desired uniform light distribution.

Accordingly, it is desirable to provide an improved light guide assembly for a vehicle instrument cluster that adequately provides uniform light distribution of both a pointer and a display of the instrument cluster.

SUMMARY OF THE INVENTION

An example light guide assembly for illuminating a display of an instrument cluster includes a light receiving portion, a light propagating portion and a reflective surface between the light receiving portion and the light propagating portion. The light receiving portion extends along a first axis, and the light propagating portion extends along a second axis which is transverse to the first axis. The reflective surface includes a stepped surface which extends transverse to the reflective surface.

An example illuminated instrument cluster includes a display having a graphic, a pointer movable relative to the graphical image, a light source, and a light guide. The light guide includes a light receiving portion disposed along a first axis, a light propagating portion disposed along a second axis which is transverse to the first axis and a reflective surface. The reflective surface includes a stepped surface which extends along the second axis.

The various features and advantages of this invention will become apparent to those skilled in the art from the following detailed description. The drawings that accompany the detailed description can be briefly described as follows.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1illustrates selected portions of a vehicle10having an instrument cluster12, such as a vehicle gauge cluster, that communicates vehicle information to occupants of the vehicle10. In the illustrated example, the instrument cluster12includes a vehicle display14having a plurality of graphics16, such as numbers, letters or symbols. At least a portion of the graphics16are illuminated from within the instrument cluster12for nighttime viewing or for aesthetic purposes, for example. In one example, the graphics16are printed on the display14. In another example, the graphics16are insert molded to the display14.

FIG. 2shows selected portions of the example instrument cluster12, including a light housing18that supports the display14and a circuit board20, such as a printed circuit board (PCB). A pointer22is mounted to the circuit board20for movement relative to the display14and is used to indicate the current status of the vehicle operating condition. The circuit board20also includes a light source24such as a light emitting diode (LED), for illuminating the display14and the pointer22simultaneously. However, other lighting types are contemplated as within the scope of the present invention.

When the instrument cluster12is assembled, the light sources24are mounted to the circuit board20and are aligned adjacent to a center27of the display14. In one example, the light sources24are at least partially aligned with a housing26of the pointer22. However, the light sources24may be positioned at other locations within the instrument cluster12.

The pointer22is driven by a shaft28of a motor30, such as a stepper motor, and is rotated to a desired position relative to the display14including the vehicle graphics16. When activated, the light source24emits light. A light guide32receives the light from each light source24, and uniformly disperses the light across the display14to evenly illuminate the vehicle graphics16of the display14, as is further discussed below.

FIG. 3illustrates the example light guide32which provides uniform illumination between the pointer22and the display14of the instrument cluster12. The light guide32is formed from a transparent material, such as clear plastic, for example. The light guide32includes a light receiving portion34, a light propagating portion36and a reflective surface38.

The light receiving portion34is disposed along an axis A, which extends transverse to the display14where the light guide32is positioned within the instrument cluster12(seeFIG. 6). The light propagating portion36extends along an axis B, which is generally parallel to the display14. Axis B is perpendicular to axis A, in one example. The reflective surface38generally extends between the light receiving portion34and the light propagating portion36.

An opening40extends through the center of the light receiving portion34along axis A. In one example, the light receiving portion34and the light propagating portion36are substantially cylindrical in shape (SeeFIG. 4). It should be understood that the light guide32is not shown to the scale it would be in practice. Instead, the light guide32is shown larger than in practice to better illustrate its function. A worker in this art would be able to determine an appropriate size, shape and configuration of the light receiving portion34, the light propagating portion36and the reflective surface38.

The reflective surface38includes a first inclined surface42, a stepped surface44, and a second inclined surface46. In this example, the stepped surface44is positioned between the first and second inclined surfaces42,46. The example stepped surface44is positioned near the midpoint of the reflective surface38. However, the stepped surface44may be positioned at any point along the reflective surface38and may be positioned exteriorly from the reflective surface38, as is further discussed below with respect toFIG. 5.

The first and second inclined surfaces42,46extend transversely to both axis A and axis B. The stepped surface44extends transversely relative to the inclined surfaces42,46. In one example, the stepped surface44extends parallel to the axis B. The stepped surface44permits a portion of light from light source24to escape through the light guide32and illuminate the pointer22, as is further discussed below with respect toFIG. 6.

In one example, the first inclined surface42and the second inclined surface46are parallel to one another. In another example, the first inclined surface42and the second inclined surface46are transverse to one another. It should be understood that the actual positioning of the inclined surfaces42,46may vary to alter the angle of reflection of light as light propagates through the light guide32.

In addition, the size relationship between the stepped surface44and the inclined surfaces42,46may be varied to control the surface ratio therebetween. A more uniform illumination of both the pointer22and display14is achieved by optimizing the surface ratio between the stepped surface44and the inclined surfaces42,46. A person of ordinary skill in the art having the benefit of this disclosure would be able to determine the appropriate surface ratio between the stepped surface44and the inclined surfaces42,46.

FIG. 5illustrates a second example light guide50. The light guide50includes a light receiving portion52and a light propagating portion54, which are identical to the light receiving portion34and the light propagating portion36of the light guide32.

In addition, the light guide50includes a reflective surface56. In this example, the reflective surface56includes an inclined surface58and a stepped surface60. The stepped surface60is positioned between opening70and the inclined surface58. The stepped surface60of the light guide50includes a flat portion62which extends parallel to axis B, in one example. The flat surface62is transverse to the inclined surface58. The stepped surface60is positioned exteriorly to the inclined surface58. The stepped surface60permits a portion of light from the light source24to escape the light guide50to illuminate a pointer22.

FIG. 6illustrates an instrument cluster12utilizing the example light guide32(SeeFIGS. 3 and 4). The light housing18of the instrument cluster12includes a reflective surface47, which extends between the circuit board20and the display14. The reflective surface47extends circumferentially about a center25of the circuit board20.

In one example, a portion of the reflective surface47of the light housing18may include a negative sloped section100. The negative sloped section100is positioned adjacent to a center25of the circuit board20and extends from the center25toward the circuit board20. In another example, the light housing18includes black dot texturing adjacent102(SeeFIG. 7) to the center25of the circuit board20. In yet another example, the light housing18includes both the negative sloped section100and the black dot texturing102. The negative sloped section100and/or black dot texturing102absorbs an increased amount of light near the light sources24of the display14, thereby improving light efficiency and providing a more uniform light distribution across the display14.

A plurality of light sources24are mounted to the circuit board20and positioned adjacent to the light guide32. In one example, four light sources24are utilized to illuminate the instrument cluster12. It should be understood that any number of light sources24may be utilized to provide the illumination necessary to adequately illuminate the instrument cluster12.

Light from each light source24is communicated into the light receiving portion34in a direction D1, which is transverse to the display14. A portion of the light L1propagates up through the light guide32, and is communicated through the stepped surface44to illuminate the pointer22. A second portion of light L2reflects off of the first and/or the second inclined surfaces42,46of the light guide32to illuminate the display14. A third portion of the light L3reflects off at least one of the inclined surfaces42,46, then off of the reflective surface47of the light housing18to illuminate the display14.

The example instrument cluster12provides for the simultaneous illumination of both the pointer22and the display14. The stepped surface44provides improved light efficiency by more uniformly distributing the light from the light sources24. A reduction of the number of light sources24needed to effectively illuminate the instrument cluster12is therefore achieved. Additionally, optimizing the surface area ratio between the stepped surface44and the inclined surfaces42,46improves illumination of the pointer22and the display14.

The foregoing description shall be interpreted as illustrative and not in any limiting sense. A worker of ordinary skill in the art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.