Abstract:
A lightpipe system for transferring light from light sources on a printed circuit board (PCB), such as light-emitting diodes (LEDs), to a display includes modular lightpipes coupled together. Each modular lightpipe couples to an adjacent modular lightpipe to form an integrated lightpipe system. All or selected numbers of the lightpipes may include detachable tabs, proturbances, pegs, or other structures to ensure proper alignment of the lightpipe system and attachment of the lightpipe system to the PCB.

Description:
TECHNICAL FIELD OF THE INVENTION 
     This invention relates to light transfer devices, and more particularly to a modular lightpipe system. 
     BACKGROUND OF THE INVENTION 
     A lightpipe transfers light from one place to another. To accomplish this, the lightpipe receives light at one of its apertures and internally reflects the light to exit at its other aperture. Thus, the lightpipe provides a channel for the light. A lightpipe may contain curves as long as the critical angle of the material, such as plastic or glass, is not exceeded. 
     Lightpipes have a variety of uses. Commonly, they find use in transferring light from a light-emitting diode (LED) on a printed circuit board (PCB) to a visual display. When used in this manner, a lightpipe can transfer light from surface mounted LEDs or through hole LEDs. However, the alignment of the lightpipe with the LED and the visual display can prove critical in ensuring proper illumination at the display end of the lightpipe. 
     Often PCBs include several LEDs in an array. To project light from the LEDs to a visual display, the PCB designer must either purchase a set of permanently connected lightpipes from a manufacturer&#39;s existing stock or have a set of permanently connected lightpipes specially made. Unfortunately, having a set of lightpipes specially made can be expensive due to tooling costs. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, the disadvantages and problems associated with previous lightpipe systems have been substantially reduced or eliminated. The present invention provides a modular lightpipe system that reduces PCB design and manufacturing cost. 
     In one embodiment of the present invention, a lightpipe system for transferring light from light-emitting diodes (LEDs) on a printed circuit board (PCB) to a visual display includes a number of modular lightpipes coupled together. In another embodiment, an electronic assembly includes a printed circuit board (PCB) having a number of light sources, a display, and a number of modular lightpipes coupled together and operable to communicate light from the light sources to the display. In yet another embodiment, a modular lightpipe includes a first coupler, a second coupler, a spacer, a first transfer channel disposed between the first coupler and the spacer, and a second transfer channel disposed between the second coupler and the spacer. 
     The present invention provides several important technical features and advantages. First, each modular lightpipe can be coupled to another modular lightpipe to form a lightpipe system. This allows the PCB designer to select the appropriate number of lightpipes for a particular LED configuration using a single lightpipe configuration. This results in reduced tooling costs. In a particular embodiment, each lightpipe includes two transfer channels to support the communication of light to two windows of the visual display. These modular lightpipes may then be coupled together to form an array that supports a display of four, six, eight, and more windows using a single modular lightpipe structure. Generally, the present invention contemplates the modular construction of a variety of light displays arranged in a linear array, two-dimensional array, or other suitable configuration using one or more modular lightpipes. 
     Other technical advantages include a modular lightpipe having a detachable tab and/or post. These detachable tabs and/or posts allow the lightpipe, system to attach to the PCB at a reduced number of points, for example, on the ends of a linear array of modular lightpipes. Lowering the number of attachment points to the PCB decreases engineering costs, production costs, and the overall footprint of the lightpipe system on the PCB. Tabs and/or posts that are not detached align the lightpipe system with the LEDs and the visual display and secure the lightpipe system to the PCB. Other technical advantages will be readily apparent to one skilled in the art from the following figures, description, and claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     For a more complete understanding of the present invention and for further features and advantages, reference is now made to the following description taken in conjunction with the accompanying drawings, where like reference numerals represent like parts, in which: 
     FIG. 1 illustrates an electronic assembly having a lightpipe system coupled to a PCB for transferring light from a number of LEDs on the PCB to a visual display; 
     FIG. 2 illustrates a modular lightpipe of the lightpipe system detached from the PCB; 
     FIG. 3 is an underside three-dimensional (3D) view of the modular lightpipe; 
     FIG. 4 is an underside 3D view of an alternative configuration of the modular lightpipe; and 
     FIG. 5 is a top view of the lightpipe system that shows the coupling between adjacent modular lightpipes. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 illustrates an electronic assembly  10  having a lightpipe system  300  attached to a printed circuit board (PCB)  100  for transferring light from a plurality of light sources  110  on PCB  100  to a visual display  200 . Lightpipe system  300  allows modular construction of a variety of light displays using one or more modular lightpipes  310 . Generally, lightpipe system  300  transfers light generated by PCB  100  to visual display  200  to permit a user to visually assess the operation and condition of electronic assembly  10 . PCB  100  contemplates any collection of electronic components. 
     The illustrated lightpipe system  300  includes four modular lightpipes  310   a ,  310   b ,  310   c ,  310   d  (generally referred to as modular lightpipes  310 ) each supporting two windows  210  in visual display  200 . Lightpipe system  300  may include more or less than four modular lightpipes  310  arranged in a linear fashion, a two-dimensional array, or other suitable configuration. Each modular lightpipe  310  may be formed from plastic (e.g., polycarbonate), glass, or other suitable light conducting material. 
     FIG. 2 illustrates modular lightpipe  310   a  of lightpipe system  300  detached from the surface of PCB  100 . With modular lightpipe  310   a  detached from the surface of PCB  100 , light sources  110  become directly observable. Light sources  110  may be surface-mounted light-emitting diodes (LEDs), protruding or hole LEDs, or any other suitable light source. Modular lightpipe  310  transfers the light emitted by light sources  110  to windows  210  in visual display  200 . In a particular embodiment, modular lightpipe  310  supports two or more light sources  110  for a single window  210  in visual display  200  to convey information on the operation and condition of electronic assembly  10  in more than one color of light (e.g., red, yellow, green). 
     Modular lightpipes  310  are coupled together by first couplers  390  and second couplers  350 . Each modular lightpipe  310  may include both a first coupler  340  and a second coupler  350 . Thus, modular lightpipes  310   a  and  310   d , the exterior units of lightpipe system  300 , possess either an unused first coupler  390  or an unused second coupler  350 . Modular lightpipes  310   a  and  310   d  include a detachable tab  320  and/or a detachable protuberance  330  to attach and align lightpipe system  300  to PCB  100 . Each tab  320  defines a hole  322  to receive a rivet, screw, or other suitable fastener  122 . PCB  100  includes a tab hole  120  corresponding to each tab  320  and a protuberance hole  130  corresponding to each protuberance  330 . In a particular embodiment, each proturbance  330  mates in a press fit to a corresponding proturbance hole  130  of PCB  100 . In addition to or in lieu of tabs  320  and/or proturbances  330 , modular lightpipe  310  may couple to PCB  100  using an ultrasonic heat stick, adhesive, or other suitable coupling. 
     Modular lightpipes  310   b  and  310   c , the inner units of lightpipe system  300 , align and attach to PCB  100  through their couplings to modular lightpipes  310   a  and  310   d . Modular lightpipes  310   b  and  310   c  may include tabs  320  and/or protuberances  330  like modular lightpipes  310   a  and  310   d . However, tabs  320  and/or protuberances  330  for modular lightpipes  310   b  and  310   c  may be removed before assembling lightpipe system  300  to reduce tooling costs for PCB  100  and to decrease the overall surface footprint of lightpipe system  300 . 
     FIG. 3 is an underside three dimensional (3D) view of modular lightpipe  310  before assembly into lightpipe system  300 . Modular lightpipe  310  includes transfer channel  312   a  and transfer channel  312   b  (referred to generally as transfer channel  312 ) spaced apart by first spacer  370  and second spacer  380 . Each transfer channel  312  includes a first aperture  314  to receive light from one or more light sources  110  corresponding to transfer channel  312 . In a particular embodiment, a single transfer channel  312  may receive light from two or more light sources  110  having different colors to provide a color-encoded visual status or condition of electronic assembly  10  at window  210  of visual display  200 . Each transfer channel  312  also includes a second aperture  316  to emit light at the visual display  200 . Spacers  370  and  380  provide support and alignment for first transfer channel  312  and second transfer channel  319 . Second spacer  380  may prevent cross bleeding of light sources  110  to adjacent transfer channels  312 . Depending on the span of transfer channels  312 , the material used to construct modular lightpipe  310 , and other factors, each modular lightpipe  310  may include one or more spacers along the length of transfer channel  312  or an integral support extending substantially along the length of transfer channel  312 . 
     In the illustrated embodiment, protuberances  330  are posts  332 . Each post  332  press fits into a corresponding protuberance port  130  in PCB  100  to align and assist in securing modular lightpipes  310  to PCB  100 . Although each modular lightpipe  310  shown includes two transfer channels  312 , each modular lightpipe  310  may include one or more transfer channels  312 . For modular lightpipes  310  having more than two transfer channels  312 , spacers  370  and  380  may be placed between adjacent transfer channels  312 . Although shown having a rectangular cross section, transfer channels  312  may include other suitable cross sections, such as circular, square, or oval. In a particular embodiment, all components of modular lightpipe  310  are integrally formed from the same light conducting material, such as plastic (e.g., polycarbonate) or glass. 
     FIG. 4 is an underside 3D view of an alternative configuration of modular lightpipe  310 , presenting another embodiment of protuberance  330 . In this embodiment, each protuberance  330  includes one or more tabs  339 . Each tab  334  or tab set extends through an associated protuberance port  130  in PCB  100  to align and assist in securing modular lightpipe  310  to PCB  100 . 
     FIG. 5 is a top view of lightpipe system  300  that demonstrates the interaction between first coupler  390  of a first modular lightpipe  310  and second coupler  350  of an adjacent modular lightpipe  310 . In a particular embodiment, first coupler  340  is a male coupling and second coupler  350  is a female coupling to engage first coupler  340  in a press fit. Each modular lightpipe  310  connects to an adjacent modular lightpipe  310  through engagement of first coupler  390  and second coupler  350 . Detachable tabs  320  may be removed from modular lightpipes  310   b  and  310   c  to reduce the footprint of lightpipe system  300 . Each first spacer  370 , second spacer  380 , first coupler  390 , and second coupler  350  may be formed with identical or different widths to provide the desired spacing consistent with light sources  110  on PCB  100  and windows  210  on visual display  200 . 
     Although the description of lightpipe system  300  has been with respect to a horizontal arrangement of modular lightpipes  310 , lightpipe system  300  contemplates other visual display configurations. For example, suppose the linear array of light sources  110  were rotated ninety degrees about the first light source, and windows  210  were rotated ninety degrees about the first window  210 . Nodular lightpipes  310  may stack vertically on top of each other using similar first couplers  340  and second couplers  350 . Lightpipe system  310  contemplates any arrangement or combination of modular lightpipes  310  to present a linear, two-dimensional, or other suitable configuration of indicator lights on visual display  200 . 
     Although the present invention has been described with several embodiments, a myriad of changes, variations, alterations, transformations, and modifications may be suggested to one skilled in the art, and it is intended that the present invention encompass such changes, variations, alterations, transformations, and modifications as fall within the scope of the appended claims.