Patent Publication Number: US-2020282903-A1

Title: Light Guide for Crossing Light in Backlight Prism

Description:
FIELD 
     The present disclosure relates to a prism to reflect and/or diffuse light emitted by a light emitting element of, for example, an instrument cluster assembly. 
     BACKGROUND 
     Instrument cluster assemblies, such as for motor vehicles, include light emitting elements to illuminate various dials and/or gauges. While such light emitting elements are suitable for their intended use, they are always subject to improvement. For example, an instrument cluster assembly, including multiple light emitting elements configured to provide improved illumination to dials and gauges with a reduced number of light reflectors and/or diffusers, that have increased effectiveness, would be desirable. 
     SUMMARY 
     The present disclosure provides an instrument cluster assembly comprising a first and second light emitting element. The first and second light emitting elements are spaced apart from one another. An optical element is positioned opposite to the first and second light emitting elements. The optical element is configured to reflect or diffuse light rays from both the first and second light emitting elements so that the light rays from the first and second light emitting elements are merged or crossed with one another. The optical element further comprises a pair of light guides to merge or cross the light rays. The pair of light guides direct the light rays to an optical layer. The first and second light emitting elements each include a pair of light emitting diodes. The first and second light emitting elements are mounted on a circuit board. The optical element may be a prism. An angled surface is positioned on the light guides to direct the light rays. 
     Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
         FIG. 1  is an exploded view of an instrument cluster assembly. 
         FIG. 2  is a perspective schematic view of the partial view of the instrument cluster assembly 
         FIG. 3  is a front plan view of the optical layer. 
         FIG. 4  is a rear plan view of  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION 
     Example embodiments will now be described more fully with reference to the accompanying drawings. 
     Turning to the figures, an instrument cluster assembly is illustrated and designated with the reference numeral  10 . The instrument cluster assembly  10  generally includes an optical layer or disk  12 , a circuit board  14 , a reflective case including a reflective case body  16  and a reflective case base  18 . A dial or applique  20 , as well as a pointer  22 , is included. The pointer  22  is mounted to a rotating member  24  such as a post extending through the aperture  30  in the optical layer. The rotating member can be rotated in a suitable manner by a suitable device such as a step motor. The aperture may also accommodate additional posts for rotating additional pointers. 
     The optical layer  12  includes a first side  36  and a second side  38 . An optical element  40  extends from the first side  36 . The second side  38  may include the applique  20  or be embossed with numerals or the like. The optical element  40  can be any suitable element, device, or structure, for example, configured to reflect and/or diffuse light, such as a prism for example. The optical element  40  will be described in further detail. 
     The circuit board  14  includes a first light emitting element  50  and a second light emitting element  52 . The first and second light emitting elements  50 ,  52  are at the outer surface  54  of the circuit board  14 , which is opposite to an inner surface  36 . The first and second light emitting elements  50 ,  52  can be any suitable light source, such as a semiconductor light source including light emitting diodes LEDs. The first and second light emitting elements  50 ,  52  can be configured to emit light having the same color or different colors. The first and second light emitting elements  50 ,  52  can also be configured to emit light having the same or similar intensities, or different intensities or orientations. Further, the first and second light emitting elements  50 ,  52  can be configured to emit light having only one color or multiple colors. The first and second light emitting elements  50 ,  52  are shown include a pair of light sources  51 ,  53 . Preferably, light sources  51 ,  53  are LEDs However, any multitude of LEDs may be arranged to provide the emitted light. One, two, three or more LEDs may be positioned to emit light to the optical element  40 . 
     The first and second light emitting elements  50 ,  52  are configured and arranged to illuminate graphics of the applique  20  or optical layer  12 . The applique and/or graphics are thus configured and arranged so they are leased partially transparent to light emitted from the first and second light emitting elements  50 ,  52 . The graphics  60  can be configured to convey a variation of information, such as a speed of the vehicle that the instrument cluster assembly is associated with. The pointer  22  can be configured to designate, for example, the appropriate graphic  60  representing the current speed of the vehicle. 
     The reflector case body  16  includes an outer surface  70  and an inner surface  72 . The reflective case body  16  defines a recess beneath the outer surface  70 . The recess  74  includes reflective sidewalls  76  that configured to direct light emitted from the first and second light emitting elements  50 ,  52  to the applique  20 . 
     The reflective case body  16  is generally between the optical layer  12  and the circuit board  14 . The optical layer  12  is arranged such that the first side is at or approximate to the outer surface of the reflective case body  16  and the optical element  40  of the optical layer  12  extends into the recess  74 . The circuit board  14  is arranged such that the first and second light emitting elements  50 ,  52  extend through, or are aligned with, one or more openings defined in the inner surface of the reflective body  16 . The first and second light emitting elements  50 ,  52  are spaced apart from one another. The optical element  40  is arranged generally opposite to the outer surface  54  of the circuit board  14 . The optical element  40  is arranged opposite to the first and second light emitting elements  50 ,  52 . The reflective case body  16 , the optical layer  12  and the circuit board  14  are seated within a receptacle  78  on the reflective case base  18 . The circuit board  14  is seated furthest within the receptacle  78 . The applique  20  is seated above the second side  38  of the optical layer  12 . 
     Turning to  FIGS. 2-4 , additional features of the optical element  40  will be discussed. The optical element  40  includes two separate light guides or light pipes  80 ,  82 . The two separate light guides  80 ,  82  may be substantially identical or may vary from one another. The light guides  80 ,  82  are positioned directly adjacent the light emitting elements  50 ,  52 . The light guides  80 ,  82  include an angled surface  84  to diffuse the light rays from the first and second light emitting elements  50 ,  52 . As the light rays are reflected or diffuse from the angled surfaces  84 , the light rays merge or cross one another in the optical layer  12 . This distributes the light through the prisms. As the light rays cross one another, they fully illuminate, or backlight, the other prism behind the applique or graphics, backlighting the instrument cluster. Thus, the light rays become crossed and are sent in opposing directions in order to fill the prism. While the aforementioned light emitting LEDs  50 ,  51 ,  52 ,  53  are in pairs in the example demonstrated here, they could be used in any combination in order ( 1 ,  2 ,  3 , etc.) to achieve the preferred final lighting condition of the applique or graphics above. 
     The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.