PATENT DOCUMENT

Publication Number: US-8562201-B2
Application Number: US-201113038167-A
Country: US
Kind Code: B2

Title: Light pipe with integrated perimeter chassis, and devices using the light pipe

Abstract:
A display assembly including an integrally formed light pipe and perimeter chassis, and a display glass above the light pipe is provided. The display glass includes transmissive elements configured to form an image on the display glass. The light pipe can be utilized to provide back-lighting for the display glass. In one embodiment, the light pipe and the perimeter chassis can be formed using a co-molding process.

Claims:
What is claimed is: 
     
       1. A display assembly comprising:
 a display glass comprising a plurality of variable transmissive elements, wherein the variable transmissive elements are configured to form one or more images on the display glass; 
 a light pipe formed from a transparent optical grade material, wherein the light pipe is configured to generate a substantially even distribution of light across a top surface of the light pipe to illuminate a bottom surface of the display glass, wherein the light pipe is configured to receive the light for distribution from one or more illumination sources arranged along an edge of the light pipe; and 
 a perimeter chassis directly bonded to the light pipe in surface regions proximate to the outer edges of the light pipe, wherein the perimeter chassis is configured to extend above the top surface of the light pipe such that an open cavity of the perimeter chassis is formed, and wherein the open cavity is configured to receive the display glass, and wherein the perimeter chassis is directly coupled to the display glass via the open cavity, and wherein the perimeter chassis and the light pipe are integrally formed and bonded to one another in a co-molding process, the bond between the light pipe and the perimeter chassis increasing a stiffness of the light pipe. 
 
     
     
       2. The display assembly of  claim 1 , wherein the light pipe and the perimeter chassis are formed from two different plastic materials selected to bond to one another during the comolding process. 
     
     
       3. The display assembly of  claim 1 , wherein the perimeter chassis extends around side edges of the light pipe and onto a top surface of the light pipe to form a substantially rectangular region that surrounds the display glass wherein the perimeter chassis is bonded to the light pipe along the side edges and the top surfaces. 
     
     
       4. The display assembly of  claim 1 , wherein one or more of the side edges of the light pipe are contoured to affect the distribution of light on the top of surface of the light pipe proximate to the edges. 
     
     
       5. The display assembly of  claim 1 , wherein the perimeter chassis formed from a relatively optically black material. 
     
     
       6. The display module of  claim 1 , wherein the perimeter chassis includes a first portion with an index of refraction that is different from a second portion. 
     
     
       7. The display module of  claim 1 , wherein the light pipe is formed in a first shot an injection molding process and the perimeter chassis is formed in a second shot of an injection molding process. 
     
     
       8. The display assembly of  claim 1 , wherein the display glass is disposed atop the top surface of the light pipe. 
     
     
       9. The display assembly of  claim 1 , wherein the open cavity of the perimeter chassis comprises a plurality of raised edges, wherein the raised edges are configured to align the display glass and the light pipe in a substantially stacked configuration. 
     
     
       10. A display comprising:
 a display glass including a plurality of variable transmissive elements, wherein the variable transmissive elements are configured to form images on the display glass; 
 a light pipe, disposed beneath the display glass, formed from a transparent optical grade material, the light pipe configured to generate a substantially even distribution of light across a top surface of the light pipe to transmit light to a bottom surface of the display glass such that the images formed on the display glass are illuminated; 
 one or more illumination sources arranged along an edge of the light pipe that generate the light that is distributed across the top surface of the light pipe; and 
 a perimeter chassis directly bonded to the light pipe in surface regions proximate to the outer edges of the light pipe, the perimeter chassis extending above the top surface of the light pipe such that a substantially rectangular cavity of the perimeter chassis is formed, wherein the substantially rectangular cavity is configured to receive the display glass, and wherein the perimeter chassis is directly coupled to the display glass via the substantially rectangular cavity, and wherein the perimeter chassis and the light pipe are bonded to one another to increase a stiffness of the light pipe. 
 
     
     
       11. The display of  claim 10 , wherein the light pipe and the perimeter chassis are integrally formed during a co-molding process and bonded to one another during the co-molding process. 
     
     
       12. The display of  claim 10 , wherein the light pipe and perimeter chassis are formed separately and then bonded together. 
     
     
       13. The display of  claim 10 , further comprising: a polarizer disposed above the display glass. 
     
     
       14. The display of  claim 10 , further comprising: a reflective layer disposed beneath the light pipe configured to reflect light exiting a bottom surface of the light pipe upwards. 
     
     
       15. The display of  claim 10 , wherein the top surface of the light pipe is textured to diffuse light exiting the top surface of the light pipe. 
     
     
       16. An electronic device comprising:
 a display comprising:
 a display glass including a plurality of variable transmissive elements, the variable transmissive elements controlled to form images on the display glass; 
 a light pipe, disposed beneath the display glass, formed from a transparent optical grade material, the light pipe configured to generate a substantially even distribution of light across a top surface of the light pipe to transmit light to a bottom surface of the display glass such that the images formed on the display glass are illuminated; 
 a plurality of light emitting diodes arranged along an edge of the light pipe that generate the light that is distributed across the top surface of the light pipe; and 
 a perimeter chassis directly bonded to the light pipe in surface regions proximate to the outer edges of the light pipe, the perimeter chassis extending above the top surface of the light pipe such that a substantially rectangular cavity of the perimeter chassis is formed, wherein the substantially rectangular cavity is configured to receive the display glass, and wherein the perimeter chassis is directly coupled to the display glass via the substantially rectangular cavity, and wherein the perimeter chassis and the light pipe are bonded to one another to increase a stiffness of the light pipe; 
 
 a processor coupled to the display for controlling the images formed on the display glass; and 
 a battery coupled to the processor and the display. 
 
     
     
       17. The electronic device of  claim 16 , wherein the light pipe includes a mixing region for mixing the light generated from the plurality of light emitting diodes. 
     
     
       18. The electronic device of  claim 16 , wherein the light pipe and the perimeter chassis are integrally formed. 
     
     
       19. The electronic device of  claim 16 , wherein the light pipe and the perimeter chassis are separately formed and then bonded to another using a bonding agent. 
     
     
       20. The electronic device of  claim 16 , wherein transmissive elements comprise liquid crystals. 
     
     
       21. The electronic device of  claim 16 , wherein the perimeter chassis includes a first portion that is substantially light reflecting and a second portion that is substantially light absorbing. 
     
     
       22. The electronic device of  claim 16 , wherein the perimeter chassis, comprising the display glass and the light pipe, is configured to fit within a housing of the electronic device.

Description:
BACKGROUND 
     1. Field of the Invention 
     The invention relates to consumer electronic devices and more particularly, methods and apparatus associated with the design of displays for thin-profile consumer electronic devices. 
     2. Description of the Related Art 
     From a visual stand point, users often find compact and sleek designs of consumer electronic devices more aesthetically appealing. As an example, portable electronic device designs that are both thin and light-weight are often popular with consumers. In some thin device designs, one face of the device is almost entirely dedicated to a viewable portion of the display while other input/output components are arranged around the sides and/or back of the device opposite the display. Typically, the display is surrounded by a thin profile enclosure where the display controller, main logic board, battery and other interface circuitry are all packaged within the enclosure. 
     Often back-lit displays are used in thin-profile electronic devices. A back-lit display, such as a liquid crystal display, can consist of a display glass component with a number of elements that can be controlled to vary the light transmissivity across the display glass. By varying the light transmissivity across the display glass, different images can be viewed on the back-lit display. 
     One objective in the design of back-lit displays is to provide relatively homogenous optical properties, such as an even lighting brightness, across the display from the edges to the center. For example, it is undesirable for the back lighting to generate local areas of brightness and dimness on the display, such as dimmer near the edges and brighter near the center. Local areas of brightness and dimness on the display are undesirable because the contrast level of the image output from the display is altered. The alteration of the contrast level of the image can cause details of the image that are viewable on a display with a more homogenous brightness to become un-viewable. 
     The distribution of the lighting brightness across a display can be affected by the placement of one or more illumination sources that generate the light emitted from the display and a path that the light from the illumination sources travels before it is emitted from the display. As an example, a light pipe can be used to distribute light from the illumination sources near the edge of the display to different parts of the display including the opposite edge of the display. The path that light takes before it is emitted from the display can include reflecting off of one or more different surfaces. Unless the surfaces are properly designed, light reflection can cause local areas of brightness and dimness on the display and subsequently distort the displayed images. 
     As consumer electronic devices and their associated display stacks are made thinner, bending of the device including the display stack becomes an issue that can affect the light emitting properties of the display. For example, the force of a user interacting with an electronic device, such as via a touch screen interface, can cause a light pipe and an associated display glass in the display underneath the touch screen to move and/or deform. The resulting movement and deformation of the light pipe can change the light paths associated with the light pipe such that its light emitting properties are altered. As the light pipe is flexed from one shape to another shape, the light emitting properties of the light pipe can be altered such that a noticeable distortion in an image output on the display is generated. 
     In view of the above, display components, such as light pipe and its supporting structure, are desired that address optical issues that can result from the structural deformation associated with operating a light-weight portable electronic device with a thin and compact enclosure. 
     SUMMARY 
     Broadly speaking, the embodiments disclosed herein describe structural components well suited for use in consumer electronic devices, such as laptops, cellphones, netbook computers, portable media players and tablet computers. In particular, structural components are described that address both strength and optical issues associated with the design of a light-weight consumer electronic device with a thin and compact enclosure and an associated thin-profile display. Methods for forming these structural components are also described. 
     In one embodiment, the consumer electronic device can be a thin-profile portable electronic device with an associated thin-profile display assembly. The display assembly can include a perimeter chassis integrally formed with a light pipe. In one embodiment, the light pipe and the perimeter chassis can be substantially rectangular shaped where the perimeter chassis is substantially hollow such that the light pipe is disposed within an interior portion the perimeter chassis. 
     A display glass including variable transmissive elements, such as liquid crystals, can be mounted above the light pipe such that it is partially disposed within and surrounded by the perimeter chassis. The light pipe can be configured to distribute light from one or more illumination sources located at one edge of the light pipe, such as light emitting diodes (LEDs). The light pipe and its surrounding structure can be designed to transmit the light along a length of the light pipe such that a bottom of the display glass is illuminated in a relative homogenous manner. A processor located within the electronic device can be configured to control the transmissive elements in the display glass such that in conjunction with the light provided by the light pipe images are output from and viewable on the display. 
     As the display assembly is thinned, the overall stiffness of the structure can be lessened. One advantage of integrally forming the light pipe and the perimeter chassis can be to increase a stiffness of the display assembly. The increase in stiffness can lessen deformations associated with the light pipe that can occur during operation of the electronic device. Thus, allowing a thinner display assembly to be utilized. Deformations of the light pipe can change its optical characteristics, such as its light distribution properties, and cause images generated on the display glass to appear distorted. Another advantage of integrally forming the light pipe and perimeter chassis is that gaps between an outer perimeter edge of the light pipe and an inner edge of the perimeter chassis can be minimized and possibly eliminated. The elimination of the gaps can minimize undesirable light leakage associated with the light pipe. 
     In particular embodiments, the perimeter chassis and the light pipe can be integrally formed using a co-molding process. For instance, the light pipe can be first formed in a first step of the molding process and then the perimeter chassis can be formed in a second step of the molding process or vice versa. The materials used for the light pipe and perimeter chassis can be selected such that in areas where the perimeter chassis and the light pipe are in contact with one another a bond is generated between the light pipe and the perimeter chassis during the co-molding processes. The coefficients of thermal expansion for the materials used to form the light pipe and the perimeter chassis can be selected so that the bonds formed during the co-molding process are maintained during contraction and expansion of the integrally formed component that can occur during operation of the electronic device. 
     In one embodiment, the light pipe can be formed from an optical grade transparent plastic, such as a polycarbonate plastic and the perimeter chassis can be formed from another type of plastic material, such as a plastic in the same material family as the light pipe. In a particular embodiment, the perimeter chassis can be formed from a “black,” i.e., a relatively non-light reflecting material. In another embodiment, the light reflecting properties of perimeter chassis can be varied throughout the component. For instance, one portion of the perimeter chassis can be “white,” such that is relatively reflective of light, while another portion of the perimeter chassis can be less reflective. 
     In particular embodiments, the light pipe can include a mixing region where light from the illumination sources is mixed. The mixing region can be relatively thicker than other portions of the light pipe. In one embodiment, an outer surface of the light pipe, such as a top surface of the light pipe opposite a bottom of the display glass can be textured. The texturing can be employed to provide a more even distribution of light emitted from the light pipe. For instance, light passing through the texturing can be diffused to increase its evenness. In other embodiments, outer edges of the light pipe can be shaped to produce a desired reflectance pattern of light near the outer edges. Portions of the outer edges of the light pipe can be surrounded by and in contact with inner edge portions of the perimeter chassis. As described above, in these areas of contact, the perimeter chassis and the light pipe may be bonded to one another. 
     Other aspects and advantages will become apparent from the following detailed description taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The described embodiments will be readily understood by the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements, and in which: 
         FIG. 1A  shows a top view of a display assembly for a portable electronic device in accordance with the described embodiments. 
         FIG. 1B  shows a side view of a display assembly for a portable electronic device in accordance with the described embodiments. 
         FIG. 2  shows a perspective view of a light pipe in accordance with the described embodiments. 
         FIG. 3  shows a cross-sectional view of a display glass and light pipe with and without deformation in accordance with the described embodiments. 
         FIGS. 4A-4B  show top views of light pipes in accordance with the described embodiments. 
         FIGS. 5A-5C  show top views of an integrally formed light pipes and perimeter chassis in accordance with the described embodiments. 
         FIG. 6  is flow chart of a method of manufacturing a portable electronic device with an integrally formed light pipe and perimeter chassis in accordance with the described embodiments. 
         FIG. 7A  shows a top view of a portable electronic device in accordance with the described embodiments. 
         FIG. 7B  shows a bottom view of a portable electronic device in accordance with the described embodiments. 
         FIG. 7C  shows block diagram of a portable electronic device in accordance with the described embodiments. 
     
    
    
     DETAILED DESCRIPTION OF THE DESCRIBED EMBODIMENTS 
     In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the concepts underlying the described embodiments. It will be apparent, however, to one skilled in the art that the described embodiments can be practiced without some or all of these specific details. In other instances, well known process steps have not been described in detail in order to avoid unnecessarily obscuring the underlying concepts. 
     A display assembly for a back-lit display can include a display glass, a light pipe and a perimeter chassis. The display glass can provide a number of controllable transmissive elements, such as liquid crystals, that can be used to form images on the display glass. To allow the images to be viewable, one or more light sources can be used to generate light that is passed through the bottom of the display glass and out towards a user viewing the images formed on the display glass. The light pipe can be used to transmit the light generated by the one or more light sources through the bottom of the display glass. The perimeter chassis can be used to support and/or align other components in a display assembly associated with the display, such as a display glass and a light pipe. The display glass and the light pipe can be partially enclosed and/or surrounded by the perimeter chassis. 
     To reduce the thickness of an electronic device, it is usually necessary to reduce the thickness of various components in the device, such as the display, while maintaining functionality of each component. Reducing the thickness of the display assembly generally requires removing structure from the assembly, such as the structure associated with the perimeter chassis, display glass and the light pipe, which tend to be among the thicker components of the display assembly. As the components of the display assembly become thinner, structural stiffness of the assembly can be lost. Structural stiffness is a concern because undesired bending can affect the optical properties of the display, such as the distribution of light generated from the light pipe, in a way that degrades the image quality output from the display. The effects of the structural stiffness on the optical properties are illustrated in more detail in the following paragraphs in reference to a couple of display assembly designs. 
     In a first design of a back-lit display assembly, the perimeter chassis can be formed as a proximately rectangular sheet. The rectangular sheet can include raised edges around its perimeter such that an open rectangular cavity is formed. The display glass and the light pipe can be sized to fit within the open rectangular cavity where the edges of the cavity keep the display glass and light pipe aligned with one another in a stacked configuration. In this example, the light pipe is positioned such that is disposed between the display glass and the rectangular sheet that forms the bottom of the perimeter chassis of the display assembly. Thus, in this design, the display assembly can include a layer associated with the perimeter chassis, a layer associated with a light pipe and a layer associated with the display glass. The bottom portion of the perimeter chassis can add to the stiffness of the display assembly and can help prevent the light pipe from moving because the light pipe is sandwiched between the display glass and the bottom portion of the perimeter chassis. 
     In a second design, to reduce the thickness of the display assembly the bottom layer of the perimeter chassis can be removed. Thus, the perimeter chassis can be a hollow rectangular shaped element that surrounds the display glass and the light pipe. When the display glass and the light pipe are disposed within the perimeter chassis, the perimeter chassis can help to keep these two components aligned with one another. 
     In the first and the second design, the light pipe may not be directly attached to the perimeter chassis but is instead suspended from the display glass. It was found that as the display assembly and its associated components, such as the display glass and the light pipe, become increasingly thinner, an actuation of a touch screen interface above the display glass can cause the display glass and the light pipe to move and deform. The movement and/or deformation of the light pipe can affect its light emitting quality such that images generated on the display glass above the light pipe can appear distorted. In the first design, the downward movement of the display glass and the light pipe are limited because the perimeter chassis includes a bottom that restricts the downward motion of the light pipe. However, in the second design, the downward motion is no longer restricted because the perimeter chassis no longer includes a bottom. 
     To mitigate the movement and/or deformation of the light pipe, one approach is to increase its stiffness and/or constrain its motion. One approach to increasing the stiffness of the light pipe is to make it thicker. However, since a design objective is to minimize the thickness of the display, increasing the thickness of the light pipe is undesirable. As will be described in more detail as follows, another approach is to attach the light pipe to the perimeter chassis to increase its stiffness. By attaching the perimeter chassis to the light pipe, the effective thickness of the light pipe and hence its stiffness is increased. However, the overall thickness of the display assembly is not increased because the perimeter chassis is already a part of the display assembly. This design is similar to the first design described above where the perimeter chassis includes a bottom except the bottom of the perimeter chassis is now formed by the light pipe. 
     The design of a thin profile display including an integrally formed light pipe and perimeter chassis and its use in portable electronic devices are discussed below with reference to  FIGS. 1A-7C . However, those skilled in the art will readily appreciate that the detailed description given herein with respect to these figures is for explanatory purposes only and should not be construed as limiting. In particular, with respect to  FIGS. 1A and 1B , top and side views of a display assembly including a light pipe integrally formed with a perimeter chassis are described. Details of a light pipe are described with respect to  FIG. 2 . Cross sectional views of a display glass and the light pipe with an external force applied are discussed with respect to  FIG. 3 . In  FIGS. 4A and 4B , light pipes with different edge shapes are discussed. The edge shapes can affect a distribution of light emitted from the light pipe. In  FIGS. 5A-5C , light pipes integrally formed with the perimeter chassis are described. Methods of generating an integrally formed light pipe and perimeter chassis are discussed with respect to  FIG. 6 . Finally, an example of a portable electronic that can include a display with an integrally formed light pipe and perimeter chassis are described with respect to  FIGS. 7A ,  7 B and  7 C. 
       FIG. 1A  shows a top view of a display assembly  100  for a portable electronic device. The display assembly  100  includes a display glass  106 . The display glass  106  may include a number of controllable elements, such as liquid crystals, with a variable transmissivity. A processor and a display controller, coupled to the display glass, can be configured to control the transmissivity of each of the elements to form images on the display glass. A light pipe  104  can be disposed beneath the display glass  106  to allow the formed images to be viewed. 
     The light pipe  104  can be configured to transmit light  101  emitted from one or more lighting elements, such as  108 . In particular embodiments, the lighting elements can be one or more light emitting diodes (LEDs) or a florescent light bulb. In the embodiment in  FIG. 1A , the lighting elements are located at one end of the light pipe  104  and light is transmitted to the opposite end of light pipe where a portion of the light is emitted upwards through the bottom of the display glass  106 . In other embodiments, the lighting elements  108  can be distributed differently. For instance, lighting elements can be located at both ends of the light pipe. In another example, the lighting elements can be located on one of the longer sides of the light pipe  101  rather than one of the short sides. In yet another example, one or more of the lighting elements can be positioned beneath the light pipe. 
     The light pipe  106  can be configured to transmit the light  101  emitted from the lighting elements  108  such that the display glass  106  is illuminated with a substantially even brightness. The substantially even brightness allows the images formed on the display glass  106  to be viewed with its intended contrast level, i.e., with the relative brightness of one portion of the image relative to another portion of the image determined by the image properties. If the brightness level generated by the light pipe  104  is uneven, then the contrast level in the image is determined by both the image properties and the variability in the brightness level of the light pipe. If the variability in the brightness levels of the light  101  is significant in the light pipe  104 , then the image formed on the display glass  106  can appear distorted. 
     The perimeter chassis  102  surrounds the display glass  106 . The display glass  106  can be sized such that it fits within the perimeter chassis  102 . When assembled in this position within the perimeter chassis, the display glass  106  can be properly aligned and held in place relative to other display assembly components, such as the light pipe  102 . The perimeter chassis  102  can be used to secure the display assembly  100  within the housing of an electronic device (e.g., see  FIG. 7A-7B .) 
     The perimeter chassis  102  and the light pipe  104  can be secured to one another in some manner. In one embodiment, the light pipe  104  and the perimeter chassis  102  can be formed separately and then bonded and/or attached together in some manner. In another embodiment, which is described in more detail as follows, the perimeter chassis  102  and the light pipe  104  can be integrally formed using a co-molding process. 
       FIG. 1B  shows a side view of a display assembly  100  for a portable electronic device. The display glass  106  can be sized to fit within the perimeter chassis such that is surrounded by the perimeter chassis. The height of the display glass  106  can extend above a height of the perimeter chassis  102 . In other embodiments, the perimeter chassis  102  can extend above the height of the display glass  106 . The display glass  106  can include a number of transmissive elements  112 . As described above, the transmissivity of each of the elements  112  can be controlled by a processor and/or a display controller to generate viewable images on the display. 
     A light polarizer  110  can be located on top of the display glass  106 . When the display assembly  100  is installed, a cover glass and a touch screen (each not shown) can be located above the polarizer  110  and the display glass  106 . A light pipe  104  is disposed beneath the display glass  106 . The light pipe  104  is configured to transmit light through a bottom of the display glass and out a top of the display glass  106 . The light transmitted through the light pipe allows images formed in the display glass  106  using the transmissive elements  112  to be viewed. 
     The perimeter chassis  102  can partially surround and be in contact with the light pipe. In areas the perimeter chassis  102  and the light pipe  104  are in contact with another, the perimeter chassis  102  and the light pipe  104  can be bonded to one another. For instance, the perimeter chassis  102  and the light pipe  104  can be bonded to one another during a co-molding process (e.g., see  FIG. 6 ). 
     A reflective layer  113  can be located beneath the light pipe  104 . The reflective layer  113  can be configured to reflect light emitted from the light pipe  104  in a downward direct back towards the light pipe. In one embodiment, a reflective layer  113  can be attached to the perimeter chassis  102  and/or the light pipe  104  using a bonding agent such as  105 . In another embodiment, a reflective coating, such as a reflective paint, can be applied to the bottom of the light pipe to form the reflective layer  113 . 
       FIG. 2  shows a perspective view of a light pipe  104  and illumination source  115 . The illumination source  115  can emit photons  120 . The light pipe  104  can include a thicker portion that acts as a mixing region  116 . In the mixing region, light from a number of illumination sources, such as different LEDs can be mixed together. The light exiting the mixing region  116  can be more uniform in its brightness than the light entering the mixing region. 
     After the light exits the mixing region  116 , it travels down the remainder of the light pipe  104  towards its opposite end. The light exiting the light pipe  104  from the sides and bottom can be reflected and/or absorbed depending on the materials that surround the light pipe. For instance, as described above with respect to  FIG. 1B , a reflective layer can be located below the light pipe  104  that is designed to reflect light exiting the bottom of the light pipe back into the light pipe. Light exiting the light pipe  104 , other than through the top of the light pipe, decreases a maximum brightness of the display glass above the light pipe. Thus, it is usually desirable to minimize the light losses through the sides and bottom of the light pipe. 
     In an embodiment described in more detail with respect to  FIGS. 5A and 5C , the material of the perimeter chassis surrounding the light pipe  104  can be a relatively optically absorptive, such as a black material. Thus, light passing out the sides of the light pipe  104  can be absorbed by the perimeter chassis and prevent light leakage into the interior of the device surrounding the light pipe  104 . In other designs in which the light pipe and the perimeter chassis are not integrally formed, a more optically reflective material can be required for the perimeter chassis because the light leakage out the sides of the light pipe can be too large. A downside of using a more optically reflective material for the perimeter chassis is light can be scattered into other portions of the interior housing where it is not desired. 
     In the embodiments described herein, the light pipe  104 , which is integrally formed with the perimeter chassis, can be thinner than other designs where the perimeter chassis and the light pipe are not integrally formed. As the light pipe  104  becomes thinner, losses out the sides of the light pipe decrease because the surface area of the sides decreases. In addition, in the embodiments described herein, the sides of the light pipe  104  can be integrated into perimeter chassis such that the gaps between the light pipe and the perimeter chassis are minimized as compared to designs where the light pipe and perimeter chassis are separately formed. The minimization of the gaps between the light pipe and perimeter chassis also can reduce light leakage. The reduced light leakage from a thinner and more closely integrated light pipe can allow a black material to be used for the perimeter chassis. In some instances, it may be desirable to use a black material for cosmetic purposes. 
     The light pipe  104  can be configured such that a majority of the light exits a top surface of the light pipe. The light exiting the top surface can enter a bottom of the display glass  106  to illuminate images formed on the display  106 . The top surface of the light pipe  104  can be textured. The texturing can be designed to evenly diffuse the light as it exits the light pipe and minimize variations in the brightness of the light across the top surface of the light pipe. In another embodiment, a layer with diffusive properties can be disposed between the light pipe  104  and the display glass  106 . 
       FIG. 3  shows a cross-sectional view of a display glass  106  and light pipe  104  integrally formed with a perimeter chassis with and without deformation. In the top of  FIG. 3 , the light pipe  104 , display glass  106  and perimeter chassis  102  are substantially flat and a first light pattern  122  from the light pipe is generated. In the bottom of  FIG. 3 , an external force is applied to the display assembly. For instance, an external force can be applied by a user that is interacting with a touch screen that is located above the glass. The application of the external force  126  can cause the light pipe  104  to slightly deform, which can slightly alter the light pattern  124  emitted from the light pipe  104 . 
     Since the light pipe  104  is anchored to the perimeter chassis, the external force  126  can be distributed throughout the light pipe and into the perimeter chassis. This spreading out of the force  126  can reduce the bending in a particular area as compared to if the force  126  is not spread out. Thus, although the light pattern  124  from the light pipe can be slightly altered due to the deformation of the light pipe  104 , the design can keep the deformation small enough that its effect on a displayed image is deemed acceptable. 
       FIGS. 4A-4B  show top views of light pipes  140  and  142 . Light pipes,  140  and  142 , include sides,  130   a ,  130   b ,  130   c  and  130   d , and sides,  132   a ,  132   b ,  132   c  and  132   d , respectively. Each of the sides of the light pipes can include an edge pattern. For instance, on light pipe  140 , side  130   a  includes edge pattern  131   a , side  130   b , includes edge pattern  131   b , side  130   c  edge pattern  131   c  and side  130   d  includes edge pattern  131   d . Further, on light pipe  142 , side  132   a  includes edge pattern  133   a , side  132   b , includes edge pattern  133   b , side  132   c  edge pattern  133   c  and side  132   d  includes edge pattern  133   d.    
     The edge patterns on each light pipe can be selected to affect the light distribution emitted from the light pipe. For instance, the edges can be shaped to produce a more even distribution of light near the edges of the light pipe. The edge patterns can vary around the sides of each light pipe, such as  140  and  142 , as well as vary from light pipe design to light pipe design. For instance, the edge pattern  133   a  on side  132   a  of light pipe  142  is different than the edge pattern  133   c  on side  133   c . Edge pattern  133   a  includes more bumps than edge pattern  133   c . As another example, edge pattern  131   b  on side  130   b  of light pipe  140  is different than edge pattern  133   b  on side  132   b  of light pipe  142 . Edge pattern  131   b  includes more and smaller bumps than edge pattern  133   b.    
     In other embodiments, the edge patterns can vary along the length of a side, such as  131   b  and  131   d . As an example, if the light sources were located near side  131   c  of light pipe  140 , then the edge patterns along sides  131   b  and  131   d  might be varied as the distance from the light source is increased. Simulations, such as simulations involving ray tracing, can be performed where light rays are emitted from the light sources proximate to the light pipe. Reflections and absorption of the light rays can be modeled as the light rays travel through the light pipe. Based upon the simulation, a prediction can be made of the intensity of the light exiting a top surface of the light pipe including the relative evenness of the light distribution. The reflections and absorption of the light rays can include modeling the reflection or absorption of light that passes through the bottom and sides of the light pipe. Based upon these simulations, the edge patterns can be shaped to produce a more even distribution of light across the top surface of the light pipe. 
       FIGS. 5A-5C  show top views of an integrally formed light pipes and perimeter chassis in accordance with the described embodiments. In one embodiment, the perimeter chassis can be co-molded with the light pipe. First, the light pipe can be molded, such as in a first shot of an injection molding process, then the perimeter chassis can be molded on top of the light pipe, such as in a second shot of an injection molding process. In other embodiments, the perimeter chassis can be formed first in a molding process followed by the light pipe. In yet other embodiments, the light pipe and the perimeter chassis can be separately formed and then molded together. 
     The materials used for the light pipe and the perimeter chassis can be different. For instance, the light pipe can be formed from an optical grade transparent material, such as a polycarbonate plastic, while the perimeter chassis can be formed from an opaque material such as an absorptive, optically black material. The material properties of the light pipe and the perimeter chassis can be selected such that the light pipe and the perimeter chassis can bond together during the injection molding process. In other embodiments, the light pipe and the perimeter chassis can be formed separately. Then, a bonding agent can be used to bond the light pipe to the perimeter chassis. 
     In  FIGS. 5A and 5B , top views of co-molded light pipes and perimeter chassis,  180  and  181  are shown. In both examples, a perimeter chassis  150  and  152 , respectively is formed over light pipe  140  described above with respect to  FIG. 4A . The dimensions of the perimeter chassis  150  and  152  can be varied to satisfy design objectives associated with the strength and optical properties of the formed components. For example, a distance between inner edge  156   a  and outer edge  156   b  of perimeter chassis  150  is smaller than the distance between inner edge  154   a  and outer edge  154   b  of perimeter chassis. Thus, perimeter chassis  152  may be stiffer than perimeter chassis  150 . 
     As another example, in  FIG. 5A , the dimensions of perimeter chassis  150  are selected such that the spaces between each of the bumps around the sides of the light pipe  140  are totally filled by the perimeter chassis  150 . In  FIG. 5B , the dimensions of the perimeter chassis  152  are selected such that a gap  156  exists between the perimeter chassis  152  and the light pipe  140  in the space between the bumps. The gap  156  can be provided to alter the optical characteristics of the light pipe, such as to improve the distribution of light emitted from the light pipe near its edges. 
     In  FIG. 5C , another embodiment of a light pipe co-molded with a chassis  182  is illustrated. In one embodiment, the optical characteristics of the perimeter chassis  182  can be selected to be constant. For instance, the perimeter chassis can be formed from a single material that is relatively absorptive and thus, optically black. In another embodiment, as shown in  FIG. 5C , the optical properties of the perimeter chassis can be vary across the surface of the perimeter chassis. As is shown, the optical properties of the perimeter chassis  160  are different in the area between inner edge  162   a  and  162   b  as compared to the rest of the chassis. For instance, one portion of the perimeter chassis  160  can be more absorptive, i.e., more black, than another portion of the perimeter chassis. The optical properties of the perimeter chassis can be varied to improve the light distribution of the light that is transmitted through the display glass since light exiting the sides of the light pipe are absorbed, reflected and scattered depending on the optical properties of the surrounding perimeter chassis. 
     In one embodiment, the perimeter chassis with varying optical properties can be formed by doping a common plastic with a material that alters its optical properties, i.e., changes its relative reflectance and absorbance. Then, the doped plastic can be injected into a mold where at a first location of the perimeter chassis in the mold a plastic with a first dopant level is injected and at a second location of the perimeter chassis in the mold a plastic with a second dopant level is injected. The injection of the plastics with different dopant levels can result in a perimeter chassis, such as  182 , where the optical properties are different at different locations. 
       FIG. 6  is flow chart of a method  200  of manufacturing a portable electronic device with an integrally formed light pipe and perimeter chassis. In  202 , the light pipe and perimeter chassis material properties can be determined. The light pipe is typically formed from an optical grade transparent material, such as a polycarbonate plastic. The plastic can be selected to be compatible with a manufacturing process, such as an injection molding process. 
     If the perimeter chassis and the light pipe are co-molded, such as in a double shot injection molding process, then the material selected for the perimeter chassis can be selected such that bond forms between the perimeter chassis and the perimeter chassis during the molding process without providing an additional bonding agent. If the perimeter chassis and light pipe are separately formed and then bonded together, a suitable bonding agent that is compatible with the materials used for the light pipe and the perimeter chassis can be selected. The coefficients of the thermal expansion for the perimeter chassis and the light pipe can be selected such that any bonds formed between the perimeter chassis and the light pipe are not broken as a result of different rates of thermal expansion between the materials and undesired bending does not occur. 
     Different optical properties for the perimeter chassis can be selected to satisfy illumination objectives associated with the light pipe such as to effect the light distribution through the top surface of the light pipe proximate to the edges. In one embodiment, to effect light distribution near the edges of the light pipe, the reflectance of the perimeter chassis can be varied from a more reflective optically white material to a more absorptive optically black material. The optical properties of the perimeter chassis may be substantially homogeneous over its surface. For instance, the perimeter chassis may be formed from a black material that is mostly light absorbing. In another embodiment, the optical properties of the perimeter chassis can vary from portion to portion. For instance, two sides of the perimeter chassis can be formed from a more reflective material (e.g., optically white) while the other sides can be formed from a more absorptive material (e.g., optically black). 
     Further, the perimeter chassis can be formed from two different materials with different indexes of refraction. First instance, a first portion of the perimeter chassis can be formed from a material with a first index of refraction and a second portion of the perimeter chassis can be formed from a material with a second index of refraction. At the boundaries between the two materials, reflection of light can occur as a result of the differences in the indexes of refraction, such as light passing from the first material to the second material. 
     In  204 , the dimensions of the chassis and the light pipe can be selected to meet strength and packaging requirements. An example of a packaging requirement can be an overall thickness of the display. An example of a strength requirement can be limiting the amount of movement of the light pipe to below a threshold value when an external force is applied to the display, such as the external force of user inputting information via a touch screen interface located above the display. The packaging and strength requirements may affect parameters such as a thickness of the light pipe and a height and thickness of the perimeter chassis. These parameters can affect one another. Thus, trade-offs can be performed involving adjusting combinations of these parameters, such as increasing a height of the perimeter chassis while reducing the thickness of the light pipe or vice versa. 
     In  206 , a light pipe edge shape can be determined. The shape of the light pipe edge can affect a distribution of light across the top surface of light and in particular the light distribution proximate to the edge of the pipe. As described above, it is desirable to provide a substantially even brightness across a top surface of the light pipe. In various embodiments, the brightness distribution across the top surface of the light pipe can be simulated using a program, such as ray tracing program, that simulates a distribution of light including its direction distribution as it enters the light pipe. Then, the light entering the light pipe can be tracked in the simulation on a photon by photon basis as it travels through the light pipe and is scattered, reflected and/or absorbed by various surfaces until it exits the light pipe. Based upon the simulation, the light distribution exiting the top surface of the light pipe can be estimated including the effects of the edge pattern of the light pipe on the light distribution across the top surface. In response to the simulation, the edge pattern of the light pipe can be adjusted to improve evenness of the light distribution across its top surface. 
     In  208 , the light pipe and the perimeter chassis component can be formed. In one embodiment, the light pipe and the perimeter chassis can be formed separately. For example, the light pipe and the perimeter chassis can be formed using two separate molding or machining processes. Then the light pipe and the perimeter chassis can be bonded together using a bonding agent, such as an epoxy. 
     In another embodiment, the light pipe and the perimeter chassis can be integrally formed in a co-molding process. For example, in a first shot of an injection molding process, the light pipe can be formed, then, in a second shot of an injection molding process, the perimeter chassis can be coupled to the light pipe. The materials for the light pipe and the perimeter can be selected such that a bond is formed between the light pipe and the perimeter chassis during the molding process. For instance, when the material for the perimeter chassis is injected over the light pipe, the surfaces of the light pipe in contact with the molten perimeter chassis may melt slightly and the perimeter chassis and light pipe material may mix together to bond the two component together. 
     In  210 , a display module included the integrated light pipe and perimeter chassis component can be formed. The assembly process can include but is not limited to one or more of coupling the illumination sources to the light pipe, adding a reflective layer beneath the light pipe, placing the display glass into a cavity formed by the perimeter chassis and light pipe or placing a polarizing layer above the display glass. In one embodiment, a diffusion layer can be placed between the light pipe and the display glass. In another embodiment, the top surface of the light pipe can be textured to provide a diffusion layer. In  212 , the assembled display module can be installed in an electronic device. 
       FIGS. 7A and 7B  show a top and bottom view of a portable computing device  400  in accordance with the described embodiments. The portable computing device and its associated form factor is provided for the purposes of illustration only and is not meant to limit the types of the devices on which an integrally formed light pipe and perimeter chassis can be used. The portable computing device can be suitable for being held in hand of a user. A cover glass  406  and a display  404  can be placed within an opening  408  of housing  402 . The display  404  can include an integrally formed light pipe and perimeter chassis as described above with respect to  FIGS. 1A-6  located within the interior of the device  400 . 
     The cover glass can include an opening for an input mechanism, such as input button  414 . In one embodiment, the input button  414  can be used to return the portable computing device to a particular state, such as a home state. A touch screen interface can be associated with the display  404 . The touch screen interface can also be used to control a state of the portable device and to provide inputs for various applications executed on the portable device. 
     Other input/output mechanisms can be arranged around a periphery of the housing  402 . For instance, a power switch, such as  410  can be located on a top edge of the housing and a volume switch, such as  412 , can be located along one edge of the housing. An audio jack  416  for connecting headphones or another audio device and a data/power connector interface are located on the bottom edge of the housing. The housing  400  also can include an aperture for a camera  415  that allows video data to be received. 
       FIG. 7C  is a block diagram of an electronic device  500  in accordance with the described embodiments. The electronic device  500  can include a processor  502  that pertains to a microprocessor or controller for controlling the overall operation of the electronic device  500 . The processor  502  can receive control signals from various input mechanisms described with respect to  FIGS. 7A and 7B . Based upon the received control signal, the processor  502  can operate the device  500  in accordance with the signal. 
     In one embodiment, the electronic device  500  can be configured to operate as a media player. In other embodiments, the electronic  500  can be configured to operate with other types of functionality, such as a cell phone, an Internet appliance, a video player, a video recorder, a game player and a voice recorder. In general, the electronic device  500  can provide a number of different functions depending on different applications that are stored on and executed by the electronic device. 
     In media player mode, the electronic device  500  can store media data pertaining to media items in a file system  504  and a cache  506 . The file system  504  can, typically, be a storage disk or a plurality of disks or a solid-state storage device, such as flash memory. The file system can provide high capacity storage capability for the media player  500 . Further, since the access time to the file system  504  can be relatively slow, the media player  500  also can include a cache  506  to decrease memory access times. The cache  506  can be, for example, Random-Access Memory (RAM) provided by semiconductor memory. 
     The electronic device  500  can also include a user input device  408  that allows a user of the electronic device  500  to interact with the electronic  500 . The user input device  508  can take a variety of forms, such as a button, keypad, dial, etc. Still further, the electronic device can include a display  510  (screen display) that can be controlled by the processor  502  to display information to the user. As described above, the display can include an integrally formed light pipe and perimeter chassis. A data bus  111  can facilitate data transfer between at least the file system  504 , the cache  506 , the processor  502 , and the CODEC  512 . 
     In one embodiment, the electronic device  500  can store a plurality of media items (e.g., songs, video files and podcasts) in the file system  504 . After instantiating a media player application on the electronic device, when a user desires to have the media player play a particular media item, a list of available media items can be displayed on the display  510 . Then, using the user input device  508 , a user can select one of the available media items. The processor  502 , upon receiving a selection of a particular media item, can supply the media data for the particular media item to a coder/decoder (CODEC)  512 . The CODEC  512  can then produces analog output signals for a speaker  514 . For a video based media item, a video CODEC can be utilized to output video images to the display  510 . The speaker  514  can be a speaker internal to the media player  500  or external to the media player  100 . For example, headphones or earphones that connect to the media player  500  would be considered an external speaker. 
     The various aspects, embodiments, implementations or features of the described embodiments can be used separately or in any combination. Various aspects of the described embodiments can be implemented by software, hardware or a combination of hardware and software. The described embodiments can also be embodied as computer readable code on a computer readable medium for controlling manufacturing operations or as computer readable code on a computer readable medium for controlling a manufacturing line. The computer readable medium is any data storage device that can store data which can thereafter be read by a computer system. Examples of the computer readable medium include read-only memory, random-access memory, CD-ROMs, DVDs, magnetic tape, and optical data storage devices. The computer readable medium can also be distributed over network-coupled computer systems so that the computer readable code is stored and executed in a distributed fashion. 
     The many features and advantages of the present invention are apparent from the written description and, thus, it is intended by the appended claims to cover all such features and advantages of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, the invention should not be limited to the exact construction and operation as illustrated and described. Hence, all suitable modifications and equivalents may be resorted to as falling within the scope of the invention.

Metadata:
Filing Date: 20110301
Publication Date: 20131022
Grant Date: 20131022
Priority Date: 20110301
Inventors: ALVAREZ RIVERA FELIX JOSE
GUILLOU JEAN-PIERRE S.
SANFORD EMERY
Assignee: APPLE INC
CPC Classifications: [{"code": "G02B6/0088", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B6/0093", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02B6/10", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02F1/1335", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B6/0093", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02B6/0088", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B6/00", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 45879019