Patent Publication Number: US-10788615-B2

Title: Light guide with preformed reflector panel

Description:
FIELD 
     The present disclosure relates generally to printed circuit boards having at least one light generating component and a light guide. 
     BACKGROUND 
     The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art. 
     Electronic assemblies with backlit visual elements may be manufactured via several processes. Most commonly, a plastic part of a polymeric material resin is molded with some portion of the plastic being clear or translucent, with electronics components including one or more light sources attached mechanically to the part after molding, so that light is visible through the clear or translucent portion, resulting in a backlighting effect. More recently, methods have been developed of embedding one or more light sources in a molded plastic part. One such method is to encapsulate light sources and associated electronics components (collectively “package”) in a clear resin via low-pressure molding and then to injection-mold plastic over or around the encapsulated package. The encapsulated package is thereby embedded in the plastic, with some portion of the plastic being clear or translucent so that light from the encapsulated package is visible through the clear or translucent plastic, resulting in a backlighting effect. 
     Another such method is to mount light sources and associated electronics (“package”) onto a polymer film, form the film into a desired shape, and then insert the formed film into an injection mold having substantially the same shape. A following step injection-molds plastic onto the film such that the package is embedded between the film on which it is mounted and the plastic that has been molded onto it, with portions of the film and/or plastic being clear or translucent such that light from the light sources is visible from the part exterior, resulting in a backlighting effect. 
     Electronics components may also be printed onto a film. The film is then inserted into an injection mold, where plastic is molded onto the film, the electronics components being embedded in the molded plastic so that when the plastic part is removed from the mold the film is peeled away from the plastic part, leaving the electronics components embedded in or adhered to the surface of the plastic part. 
     Thus, while current printed film assemblies achieve their intended purpose, there is a need for a new and improved system and method for preparing light guides used for film assemblies having light emitting diodes. 
     SUMMARY 
     According to several aspects, a molded component assembly includes a printed circuit board with a first face and an oppositely facing second face. Multiple light emitting diodes are mounted on a first portion of the first face. A light guide of a light translucent polymeric material includes: a contact surface; an outer surface oppositely facing with respect to the contact surface; and multiple light outlets; wherein the contact surface contacts the first portion of the first face having the light guide seated over the light emitting diodes and directly receives visible light from the light emitting diodes and transmits the visible light to the light outlets. A reflector plate is disposed over and directly contacts the outer surface of the light guide. The reflector plate includes multiple filler members extending into the light guide. The reflector plate reflects visible light transmitted toward the outer surface of the light guide back into the light guide. 
     In another aspect of the present disclosure, the reflector plate is a white color. 
     In another aspect of the present disclosure, the reflector plate has a partial cavity corresponding in shape to and receiving the light guide when the reflector plate directly contacts the outer surface of the light guide. 
     In another aspect of the present disclosure, the light outlets of the light guide each define a generally U-shaped cavity. The multiple filler members each extend away from a lower surface of the reflector plate and are each sized to fit into one of the light outlets, with each of the filler members extending into one of the light outlets when the reflector plate directly contacts the outer surface of the light guide. 
     In another aspect of the present disclosure, the light guide includes multiple male projections; and the reflector plate includes multiple apertures each frictionally receiving one of the male projections of the light guide to retain the reflector plate in contact with the light guide. 
     In another aspect of the present disclosure, the light guide includes multiple light lenses each having multiple beveled surfaces that are non-orthogonal with the contact surface to reflect the visible light to the light outlets. 
     In another aspect of the present disclosure, a portion of the reflector plate directly contacts a planar reflector surface of each of the light lenses. 
     In another aspect of the present disclosure, the printed circuit board includes multiple through apertures extending from the first face toward the second face; and each of the light lenses includes a male extension portion extending over one of the through apertures in the printed circuit board, wherein light emitted by the light emitting diodes and received in the light guide is outlet through the male extension portion of each of the light lenses via the through apertures. 
     In another aspect of the present disclosure, each male extension portion of each of the light lenses includes a distal end positioned flush with the second face of the printed circuit board. 
     In another aspect of the present disclosure, each male extension portion of each of the light lenses includes a distal end spaced apart from the second surface of the printed circuit board. 
     In another aspect of the present disclosure, multiple electronics components are disposed on a second portion of the first face of the printed circuit board, and a layer of a polymeric material is overmolded over the electronics in the second portion of the printed circuit board. 
     In another aspect of the present disclosure, the light guide and the layer are integrally formed. 
     In another aspect of the present disclosure, multiple light emitting diode receiving pockets define recesses in the contact surface, each sized to receive one of the light emitting diodes when the contact surface directly contacts the first portion of the first face. 
     In another aspect of the present disclosure, the light emitting diodes define side firing diodes, with visible light emitted from the light emitting diodes directed generally parallel to the first surface. 
     According to several aspects, a molded component assembly includes a printed circuit board with a first face and an oppositely facing second face. Multiple light emitting diodes are mounted on a first portion of the first face. Multiple electronics components are mounted on a second portion of the first face. A light guide of a light translucent polymeric material has a contact surface directly contacting the first portion of the first face and multiple light outlets defining cavities in the light guide. The light guide is seated over the light emitting diodes and directly receives visible light from the light emitting diodes and transmitting the visible light to the light outlets. A reflector plate directly contacts the light guide and extends over the second portion of the first face including the electronics components. The reflector plate reflects visible light transmitted to the reflector plate back into the light guide. 
     In another aspect of the present disclosure, the printed circuit board includes multiple through apertures individually positioned proximate to individual ones of the light emitting diodes. 
     In another aspect of the present disclosure, the reflector plate includes multiple filler members each extending away from a lower surface of the reflector plate and each sized to fit into one of the light outlets, each of the filler members substantially surrounding one of the through apertures except between opposed end faces of the filler members where light from the light emitting diodes enters. 
     In another aspect of the present disclosure, the light guide includes multiple light lenses co-molded of the polymeric material and homogeneously connected to the light guide, each extending into one of the light outlets and each extending at least partially into one of the through apertures. 
     In another aspect of the present disclosure, an outer surface of the light guide oppositely facing with respect to the contact surface, wherein the reflector plate directly contacts the outer surface of the light guide. 
     According to several aspects, a molded component assembly includes a printed circuit board with a first face and an oppositely facing second face. Multiple light emitting diodes are mounted on a first portion of the first face. Multiple electronics components are mounted on a second portion of the first face. A light guide of a light translucent polymeric material has a contact surface directly contacting the first portion of the first face and multiple light outlets defining cavities in the light guide. The light guide is seated over the light emitting diodes and directly receives visible light from the light emitting diodes and transmits the visible light to the light outlets. An outer surface of the light guide is oppositely facing with respect to the contact surface. A reflector plate is disposed over and directly contacts the outer surface of the light guide and extends over the second portion of the first face including the electronics components. The reflector plate includes multiple filler members each extending away from a lower surface of the reflector plate each sized to fit into one of the light outlets, with each of the filler members extending into one of the light outlets when the reflector plate directly contacts the outer surface of the light guide. The reflector plate reflects visible light transmitted to the outer surface of the light guide back into the light guide. 
     Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples 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 illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
         FIG. 1  is a front perspective assembly view of a laminated light guide and component carrier according to an exemplary embodiment; 
         FIG. 2  is a top plan view of an assembled laminated light guide and component carrier of  FIG. 1 ; 
         FIG. 3  is a rear perspective view of area  3  of  FIG. 2 ; 
         FIG. 4  is an end perspective view of area  4  of  FIG. 2 ; 
         FIG. 5  is a bottom plan view of the laminated light guide and component carrier of  FIG. 1 ; 
         FIG. 6  is a side perspective assembly view of the reflector plate and the light guide of  FIG. 1  prior to assembly; and 
         FIG. 7  is a top perspective view of the assembled reflector plate and light guide of  FIG. 6 . 
     
    
    
     DETAILED DESCRIPTION 
     The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. 
     Referring to  FIG. 1 , a laminated light guide and component carrier defining a molded component assembly  10  includes a molded body  12  such as a printed circuit board having multiple electrical components mounted thereon. According to several aspects, the molded body  12  defines a rectangular shape, however any desired geometric shape may be used. The molded body  12  includes a first side or first face  14  and an oppositely directed second face  15 . On the first face  14  of the molded body  12  are located multiple electronics components  16  including capacitors, which are electrically connected to a plurality of first electrical traces  18 ,  19  (only partially shown for clarity) printed for example by a screen printing process onto the first face  14 . 
     Multiple light emitting diodes  20 ,  20 ′,  20 ″,  20 ′″,  20 ″″ are also individually mounted on a first portion  21  of the first face  14  and are connected to the electrical traces  18 ,  19 . An additional light emitting diode  22  can optionally be provided at one end of the first portion  21  of the first face  14  of the molded body  12  to provide an illuminated indication that electrical power is available for the molded component assembly  10 . According to several aspects, the multiple electronics components  16  are disposed on a second portion  23  of the first face  14  of the molded body  12 . According to several aspects, the light emitting diodes  20 ,  20 ′,  20 ″,  20 ′″,  20 ″″ define side firing diodes, with visible light emitted from the light emitting diodes directed generally parallel to the first face  14 . 
     Positioned proximate to each of the light emitting diodes  20 ,  20 ′ are multiple individual through apertures  24 ,  24 ′,  24 ″,  24 ′″,  24 ″″ created in the molded body  12 . According to several aspects each of the through apertures  24 ,  24 ′,  24 ″,  24 ′″,  24 ″″ are square or rectangular shaped, however any geometry can be selected. A separate through aperture  26  may also be provided proximate to the light emitting diode  22 , which is similar to the through apertures  24 ,  24 ′,  24 ″,  24 ′″,  24 ″″ in function, but may have a smaller cross section. Also positioned on the first face  14  of the molded body  12  is a connector  28  which is connected to the electrical traces  18 ,  19 . Multiple capacitive touch film contacts  30  are provided proximate to a space envelope of the connector  28 . Multiple through apertures  32  are provided through the molded body  12  which frictionally receive pins discussed below. 
     A light guide  34  is molded from a single injection molding shot of an optically clear polymeric material such as polymethyl methacrylate (PMMA) which is transparent or translucent to allow light passage through the light guide  34 . Multiple light emitting diode receiving pockets  36 ,  36 ′,  36 ″,  36 ′″,  36 ″″ are formed that open from a contact surface  38  defining a molded body facing side of the light guide  34 . Each of the pockets  36 ,  36 ′,  36 ″,  36 ′″,  36 ″″ is sized to receive and partially surround one of the light emitting diodes  20 ,  20 ′,  20 ″,  20 ′″,  20 ″″ when the light guide  34  is press-fit onto the first face  14  of the molded body  12 . A separate pocket  40  is also created in the light guide  34  which receives the light emitting diode  22 . 
     Multiple generally U-shaped cavities defining light outlets  42 ,  42 ′,  42 ″,  42 ′″,  42 ″″ are created through the light guide  34  each aligned with individual ones of the through apertures  24 ,  24 ′,  24 ″,  24 ′″,  24 ″″ when the light guide  34  is press-fit onto the first face  14  of the molded body  12 . Multiple light reflectors or light lenses  44 ,  44 ′,  44 ″,  44 ′″,  44 ′″, co-molded of the PMMA material and homogeneously connected to the light guide  34  each extend into one of the light outlets  42 . Each of the light lenses  44 ,  44 ′,  44 ″,  44 ′″,  44 ″″ includes a planar reflector surface  45  oriented substantially parallel to the contact surface  38 . When the light guide  34  is positioned on the molded body  12  each of the light lenses  44 ,  44 ′,  44 ″,  44 ′″,  44 ″″ substantially overlaps one of the through apertures  24 ,  24 ′,  24 ″,  24 ′″,  24 ″″ with the light guide  34  press-fit onto pins described below extending from the first face  14  of the molded body  12 . A separate light lens  46  also co-molded of the PMMA material and homogeneously connected to the light guide  34  overlaps the through aperture  26  when the light guide  34  is positioned on the molded body  12 . 
     Multiple male projections defining first pins  48  co-molded of the PMMA material and homogeneously connected to the light guide  34  extend upwardly as viewed in  FIG. 1  away from an outer surface  50  of the light guide  34 . A separate male projection defining an alignment pin  52  which is longer than the first pins  48  can also be provided. In addition to the first pins  48  extending from the outer surface  50 , multiple male projections defining second pins  54 , only one of which is partially visible in this view, extend downwardly away from the contact surface  38 . Each of the second pins  54  is frictionally received in one of the through apertures  32  formed in the molded body  12  when the light guide  34  is press-fit onto the first face  14  of the molded body  12 . 
     A reflector plate  56  of a polymeric material such as an injected resin or a stamped film is molded using a molding process. The reflector plate  56  is positioned in direct contact with the outer surface  50  of the light guide  34  and covers the electronics components  16 , and directly contacts a portion of the first face  14  of the molded body  12 . According to several aspects, the reflector plate  56  is white in color to reflect visible light created when the light emitting diodes  20 ,  20 ′,  20 ″,  20 ′″,  20 ″″,  22  are energized which would otherwise escape through the light guide  34  and return the light back into the light guide  34 . When the light guide  34  is positioned on the molded body  12  a portion of the reflector plate  56  also directly contacts the planar reflector surface  45  of each of the light lenses  44 ,  44 ′,  44 ″,  44 ′″,  44 ′″. Multiple filler members  58  are co-molded with and homogeneously extend from a lower surface  60  of the reflector plate  56 . Each of the filler members  58  is sized to be slidably received in and to substantially fill one of the cavities defining the light outlets  42  extending through the light guide  34  when the lower surface  60  is brought into direct contact with the outer surface  50  of the light guide  34 . The light outlets  42  created in the light guide  34  receive the filler members  58  which extend from the reflector plate  56  to add white reflective material of the reflector plate  56  directly into the light guide  34 . 
     A first thickness  62  of the reflector plate  56  in in a first section  64  of the filler members  58  is less than a second thickness  66  defining a second section  68  of the reflector plate  56 . A contact surface  70  is created in the second section  68  having the second thickness  66 , and a partial cavity  72  is provided in the first section  64  having the filler members  58 . The contact surface  70  directly contacts an area  74  of the first face  14  of the molded body  12  when the reflector plate  56  is brought into direct contact with each of the light guide  34  and the molded body  12 , with the light guide  34  positioned within the partial cavity  72 . Each of the first pins  48  of the light guide  34  are frictionally received in one of multiple through apertures  76  created in the reflector plate  56  to fix the reflector plate  56  onto the light guide  34 . A full thickness body portion  78  of the reflector plate  56  is created outside of the partial cavity  72 , which provides the contact surface  70 . 
     Referring to  FIG. 2  and again to  FIG. 1 , a completed assembly of the molded component assembly  10  provides the light guide  34  frictionally coupled to the molded body  12  using the second pins  54 , and the reflector plate  56  overlayed onto and frictionally coupled to both the light guide  34  and the molded body  12  using the first pins  48  and the alignment pin  52 . In the assembled condition, each of the light emitting diodes such as the light emitting diode  20  is received in one of the pockets such as the pocket  36 . Light generated by each light emitting diode as visible light is directed primarily toward the light lens of its associated light guide, such as from the light emitting diode  20  toward the light lens  44 , in the direction of a light arrow  80 . Each light guide disperses light out via one of the through apertures  24 ,  24 ′,  24 ″,  24 ′″,  24 ″″, for example light from the light emitting diode  20  is dispersed through the light lens  44  out via the through aperture  24 . The openings provided in the light guide  34  via the light outlets  42  surrounding the light guides help limit light dispersion through only one of the through apertures via only one of the light guides, such as through the through aperture  24  via the light lens  44 . 
     Light rays as visible light emitted from the light emitting diodes  20 ,  20 ′,  20 ″,  20 ′″,  20 ″″ reflect off multiple beveled surfaces  82 ,  84 ,  86  of each of the light lenses  44 , which direct the light rays out the through apertures  24 ,  24 ′,  24 ″,  24 ′″,  24 ″″. Light rays emitted by the light emitting diode  22  are directed out the through aperture  26 . The light rays as visible light pass through graphics (not shown) created on a finish layer of an acrylonitrile butadiene styrene (ABS) plastic (not shown) of the molded component assembly  10 . The angles of the beveled surfaces  82 ,  84 ,  86  are each oriented approximately 45 degrees with respect to the contact surface  38  which is oriented parallel to the outer surface  50  of the light guide  34 . The beveled surfaces  82 ,  84 ,  86  reflect and direct the light to intensify the light toward a center of each of the light lenses  44 . Visible light emitted by the light emitting diodes  20 ,  20 ′,  20 ″,  20 ′″,  20 ″″,  22  also reflects off the white reflector plate  56  back toward the light guide  34  and the molded body  12 , and is thereby available to be reflected off the multiple beveled surfaces  82 ,  84 ,  86  and out the through apertures  24 ,  24 ′,  24 ″,  24 ′″,  24 ″″. 
     Referring to  FIG. 3  and again to  FIGS. 1 through 2 , the second portion  23  of the body  12  having the electronics components  16  mounted thereon is generally not covered by the light guide  34 . To encapsulate and environmentally protect the electronics components  16 , a first polymeric material  88  is molded over the second portion  23  of the first face  14  encapsulating the electronics components  16  and contacting a portion  90  of the light guide  34 . According to several aspects, a second polymeric material  92  is over-molded over the light guide  34  and at least partially over the first material  88 . 
     Referring to  FIG. 4  and again to  FIGS. 1 through 3 , to the maximum extent possible, a minimum clearance  94  is maintained between the edge  90  of the light guide  34  in its installed position on the molded body  12  and any of the electronics components  16  such as an exemplary electronic component  16 ″. According to several aspects, the minimum clearance  94  is approximately 0.2 mm which provides for tolerance stack-up and thermal expansion between components. 
     Referring to  FIG. 5  and again to  FIGS. 1 through 4 , each of the multiple filler members  58 ,  58 ′,  58 ″,  58 ′″,  58 ″″ are shown in the installed positions. A partial thickness of the molded body  12  has been removed for clarity, presenting the filler member  58 ′″, and the light lens  44 ′″ more clearly. The following discussion of the filler member  58 ′″ and the light lens  44 ′″ therefore applies equally to all of the filler members and light lenses. The filler member  58 ′″ substantially surrounds the through aperture  24 ′″ except between opposed end faces  96 ,  98  where light from the light emitting diode  20 ′″ enters the light lens  44 ′″. A distal end  100  of the light lens  44 ′″ defines a substantially flat face having a geometry that substantially matches a geometry of the through aperture  24 ′″, and thereby covers the through aperture  24 ′″ to create a light outlet. According to several aspects, the distal end  100  is positioned flush with the second face  15  of the molded body  12 . According to further aspects, the distal end  100  is positioned at least partially within the through aperture  24 ′″ but is spaced apart from the second face  15  of the molded body  12 . Light generated by the light emitting diode  20 ′″ enters the light lens  44 ′″, reflects off each of the beveled surfaces  82 ,  84 ,  86 , and is dispersed from the distal end  100  defining the light outlet from the through aperture  24 ′″ in a direction toward the viewer as shown in  FIG. 5 . 
     Referring to  FIG. 6  and again to  FIG. 1 , the reflector plate  56  is shown in position prior to assembly onto the light guide  34 . To install the reflector plate  56  each of the filler members  58 ,  58 ′,  58 ″,  58 ′″,  58 ″″ such as the filler member  58 ′″ is aligned with one of the light outlets  42 ,  42 ′,  42 ″,  42 ′″,  42 ″″ such as the light outlet  42 ″″ and the reflector plate  56  is pressed onto the light guide  34  in a direction  102  until each of the filler members  58 ,  58 ′,  58 ″,  58 ′″,  58 ″″ are slidably received in one of the light outlets  42 ,  42 ′,  42 ″,  42 ′″,  42 ″″. At the same time, individual ones of the pins  48 ,  52  are frictionally received in individual ones of the apertures  76  to frictionally lock the reflector plate  56  onto the light guide  34 . As the lower surface  60  of the reflector plate  56  directly contacts the outer surface  50  of the light guide  34  each of the planar reflector surfaces  45  of the light lenses  44 ,  44 ′,  44 ″,  44 ′″,  44 ″″ also directly contacts the lower surface  60 . 
     Referring to  FIG. 7  and again to  FIGS. 1 and 6 , a completed assembly of the reflector plate  56 , the light guide  34 , and the molded body  12  which together defines the molded component assembly  10  positions the side firing light emitting diodes  20 ,  20 ′,  20 ″,  20 ′″,  20 ″″ such as the light emitting diode  20 ″″ to emit light rays which are reflected off the individual beveled surfaces  82 ,  84 ,  86  of each of the light lenses  44  such as the light lens  44 ″″, and are reflected off of the filler members  58 ,  58 ′,  58 ″,  58 ′″,  58 ″″ such as the filler member  58 ″″ to exit downwardly as viewed in  FIG. 7  out of the through apertures  24 ,  24 ′,  24 ″,  24 ′″,  24 ″″ shown and described in reference to  FIG. 1 . Light rays which travel upwardly as viewed in  FIG. 7  are reflected off the white reflector plate  56  and back down toward the through apertures. By separating each of the filler members  58 ,  58 ′,  58 ″,  58 ′″,  58 ″″ into one of their own assigned light outlet  42 ,  42 ′,  42 ″,  42 ′″,  42 ″″ light from individual light emitting diodes is segmented and therefore predominantly emitted only from one of the through apertures  24 ,  24 ′,  24 ″,  24 ′″,  24 ″″. Individual ones of the light emitting diodes  20 ,  20 ′,  20 ″,  20 ′″,  20 ″″ can therefore be energized and their light rays segmented. 
     A molded or laminated light guide and component carrier defining a molded component assembly  10  of the present disclosure offers several advantages. These include provision of a white reflector plate directly onto a light transmissive light guide which reflects light off the white reflector plate back into the light guide. Cavities created in the light guide receive filler portions extending from the reflector plate to add reflective material of the reflector plate directly into the light guide. Light lenses of the light guide also extend into the cavities to maximize the reflection of light emitted from light emitting diodes positioned proximate to the light lenses. 
     The description of the present disclosure is merely exemplary in nature and variations that do not depart from the gist of the present disclosure are intended to be within the scope of the present disclosure. Such variations are not to be regarded as a departure from the spirit and scope of the present disclosure.