PATENT DOCUMENT

Publication Number: US-7940365-B2
Application Number: US-65013307-A
Country: US
Kind Code: B2

Title: Compact display flex and driver sub-assemblies

Abstract:
Compact sub-assemblies of flexible circuits and drivers are provided. The sub-assemblies can occupy less space in an electronic device than conventional sub-assemblies. In one or more embodiments of the present invention, the flexible circuits can be attached to or wires can be disposed on portions of the substrate that previously were unoccupied in conventional sub-assemblies. In one or more embodiments, the sub-assemblies of the present invention also can have wires disposed underneath the driver or vary the width of the wires. In one or more embodiments, the sub-assemblies of the present invention also can have composite wires that occupy less space than wires of conventional sub-assemblies, while still maintaining similar energy flux.

Claims:
1. An assembly comprising:
 a non-conductive substrate; 
 a first set of wires disposed on the non-conductive substrate, wherein a first wire of the first set of wires has a first termination region for operatively coupling the first wire to a first electronic component and a second termination region for operatively coupling the first wire to a second electronic component; and 
 multiple electrical contacts positioned on the first termination region of the first wire. 
 
     
     
       2. The assembly of  claim 1 , wherein the multiple electrical contacts are positioned in a side-by-side orientation on the first termination region of the first wire. 
     
     
       3. The assembly of  claim 1 , wherein the multiple electrical contacts are positioned in a stacked orientation on the first termination region of the first wire. 
     
     
       4. The assembly of  claim 1 , wherein the multiple electrical contacts are positioned in a staggered orientation on the first termination region of the first wire. 
     
     
       5. The assembly of  claim 1 , wherein the substrate and the first set of wires form a flexible circuit. 
     
     
       6. The assembly of  claim 1 , wherein the first electronic component comprises a flexible circuit and the second electronic component comprises a display driver, the assembly further comprising a second set of wires on the substrate to operatively couple the display driver to a set of pixel activation components. 
     
     
       7. The assembly of  claim 6 , wherein the flexible circuit has a first width and the display driver has a second width that is greater than the first width. 
     
     
       8. The assembly of  claim 6 , wherein at least portions of the first and second set of wires are disposed adjacent to each other, without any intervening electronic components. 
     
     
       9. The assembly of  claim 1 , wherein:
 a second wire of the first set of wires has a termination region disposed in a staggered configuration with respect to the first termination region of the first wire. 
 
     
     
       10. The assembly of  claim 1 , wherein the assembly has a form factor suitable for incorporation within a hand-held electronic device. 
     
     
       11. The assembly of  claim 1 , wherein the non-conductive substrate comprises a substrate suitable for electronic displays. 
     
     
       12. A method for manufacturing an assembly, the method comprising:
 providing a substrate; 
 disposing a first set of wires on the substrate, wherein a first wire of the first set of wires has a first termination region for operatively coupling the first wire to a first electronic component and a second termination region for operatively coupling the first wire to a second electronic component; and 
 positioning multiple electronic contacts on the first termination region. 
 
     
     
       13. The method of  claim 12 , wherein positioning multiple electronic contacts comprises positioning the multiple electronic contacts in a side-by-side orientation on the first termination region. 
     
     
       14. The method of  claim 12 , wherein positioning multiple electronic contacts comprises positioning the multiple electronic contacts in a stacked orientation on the first termination region. 
     
     
       15. The method of  claim 12 , wherein positioning multiple electronic contacts comprises positioning the multiple electronic contacts in a staggered orientation on the first termination region. 
     
     
       16. The method of  claim 12 , wherein the first electronic component comprises a flexible circuit and the second electronic component comprises a display driver, the method further comprising disposing a second set of wires on the substrate to operatively couple the display driver to one or more additional electronic components, wherein at least a portion of the second set of wires is disposed adjacent to the first set of wires, without any intervening electronic components. 
     
     
       17. The method of  claim 12 , further comprising disposing pixel activation components on the substrate.

Description:
FIELD OF THE INVENTION 
     The present invention relates to compact flexible circuit and driver sub-assemblies for an electronic device. 
     BACKGROUND OF THE INVENTION 
     Many currently available electronic devices have displays that provide graphics to the user. To drive pixels of the display, a conventional display assembly can incorporate a display driver operatively coupled via wires to a flexible circuit. The flexible circuit (also referred to herein as a “flex”) can be operatively coupled to a circuit board of the electronic device using, e.g., board-to-board connectors. The circuit board can have a controller for generating signals that instruct the display driver to selectively drive pixels of the display. 
     Consumers are demanding increasingly smaller electronic devices with increasingly larger displays. Consequently, space within the devices has become increasingly limited. In particular, the size of the electronic device and display can be limited, in part, by the space occupied by the display driver, the flex, and the wires that operatively couple the two components. 
     SUMMARY OF THE INVENTION 
     The present invention can include compact flex and driver sub-assemblies for an electronic device. The compact sub-assemblies can reduce the amount of space occupied by the flex, the driver, and the wires that operatively couple the two components. 
     In one or more embodiments of the present invention, this can be accomplished by providing a flex with one or more attachment portions that attach to previously unused areas on a substrate on which the driver is disposed. This can reduce or eliminate the areas of the substrate to which the flex used to be attached in conventional designs. For example, in conventional display assemblies, some areas of the substrate disposed laterally adjacent to the driver may not be occupied by other components. Thus, the flex can be attached to those areas of the substrate. Wires can be disposed in a multi-dimensional (e.g., 2-D or 3-D) pattern on the substrate to operatively couple the driver to portion(s) of the flex attached to the substrate. 
     In one or more embodiments of the present invention, the space within the electronic device occupied by the flex and driver sub-assembly can be reduced by reducing the maximum width of the flex to be less than that of the driver. To evenly distribute and balance the signal lines across the entire width of the driver, one or more of the wires that operatively couple the flex to the driver can be run underneath the driver. Thus, at least one wire can be disposed in an area of the substrate on which the driver also is to be disposed, directly or indirectly. 
     Another embodiment of the present invention can include staggered wire layouts that facilitate coupling of a flex to a substrate when the wires on both components are not co-linearly disposed with each other at or near the regions in which the two components are attached. 
     Another embodiment of the present invention also can include sub-assemblies having wires with widths that vary from wire to wire, and/or that vary along the same wire. This can permit a wire to be tailored for specific impedance levels, while accommodating the limited surface area on which the wires can be disposed. 
     Another embodiment of the present invention also can include composite wires that deliver similar energy flux as multiple wires in conventional sub-assemblies, but that occupy less space. This can permit the flex to have a narrower width and/or for the wires to occupy less space on the substrate. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other advantages of the present invention will be apparent upon consideration of the following detailed description, taken in conjunction with accompanying drawings, in which like reference characters refer to like parts throughout, and in which: 
         FIGS. 1A-1B  show a prior art display assembly having a flex and driver sub-assembly; 
         FIGS. 2A-2B  illustrate a compact flex and driver sub-assembly in accordance with a first embodiment of the present invention; 
         FIG. 3  illustrates a compact flex and driver sub-assembly in accordance with a second embodiment of the present invention; 
         FIG. 4  illustrates a compact flex and driver sub-assembly in accordance with a third embodiment of the present invention; 
         FIG. 5  illustrates a compact flex and driver sub-assembly in accordance with a fourth embodiment of the present invention; 
         FIG. 6  illustrates a compact flex and driver sub-assembly in accordance with a fifth embodiment of the present invention; and 
         FIGS. 7A-7C  illustrate a staggered wire pattern in accordance with one embodiment of the present invention; 
         FIG. 8  illustrates a wire pattern in accordance with one embodiment of the present invention; 
         FIG. 9A  illustrates prior art wires used in conventional flex and driver sub-assemblies; 
         FIGS. 9B-9D  show illustrative composite wires in accordance with one or more embodiments of the present invention; and 
         FIG. 10  shows illustrative electronic devices in which flex and driver sub-assemblies of the present invention can be incorporated. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIGS. 1A-1B  show a prior art display assembly having a flex and driver sub-assembly. Display assembly  10  can include pixel activation substrate  12 , color filter substrate  14 , polarizing substrates  16 , driver  18 , and flex  20 . Pixel activation components and color filters can be interposed between substrates  12  and  14 . Color filter substrate  14  can be disposed on top of pixel activation substrate  12 . Polarizing substrates  16  can sandwich pixel activation substrate  12  and color filter substrate  14  therebetween. These stacking arrangements are merely illustrative. 
     Pixel activation components can include components that energize and/or define one or more pixels in the display. For example, in active liquid crystal displays, pixel activation components can include a matrix of thin film transistors that can energize liquid crystals in the display. The area in which the pixel activation components are disposed can define active area  22  of the display in which graphics can be provided to users. Display assembly  10  also can include pixel active components for other types of display technologies, e.g., passive liquid crystal displays, plasma displays, organic light emitting diode displays, surface-conduction electron emitter displays, or any other type of display technology known in the art or otherwise. 
     In conventional display assembly  10 , pixel activation substrate  12  can have driver ledge  24  on which display driver  18  and flex  20  are disposed, directly or indirectly. To drive pixel activation components of display assembly  10 , display driver  18  can be operatively coupled to the pixel activation components via driver-to-active area fan-out  26 . Fan-out  26  can include a set of wires disposed on pixel activation substrate  12 , directly or indirectly. Display driver  18  can be driven by signals transmitted through flex  20 , which can be operatively coupled to driver  18  using flex-to-driver fan-out  28 . Fan-out  28  also can include a set of wires disposed on pixel activation substrate  12 , directly or indirectly. Flex  20 , in turn, can be operatively coupled to a circuit board (not shown) that generates signals for instructing driver  18  to selectively drive pixels of the display. 
     In conventional flex and driver sub-assemblies, flex  20  and driver  18  can communicate using parallel signal transmission. The width of the portion of flex  20  attached to driver ledge  24  typically can be greater than or substantially equal to the width of driver  18  to permit flex-to-driver fan-out  28  to have a sufficient number of wires for parallel signal transmission. In conventional display assembly  10 , the length, cross-sectional area, and material of all the wires of flex-to-driver fan-out  28  are substantially uniform so that each wire in fan-out  28  has substantially the same nominal impedance. The nominal impedance can be based on the maximum specified impedance for the signals transmitted between driver  18  and flex  20 . 
     The conventional design illustrated in  FIGS. 1A-1B  can suffer some disadvantages. First, driver ledge  24  can have areas that are not occupied by any components of the flex-to-driver sub-assembly. This can be an inefficient use of space. Second, due to the configuration of flex-to-driver fan-out  28  and the consequent width of flex  20 , the flex can occupy a lot of space within the electronic device. Unfortunately, as electronic devices become smaller and displays become larger, the space occupied by display driver  18 , flex  20 , and flex-to-driver fan-out  28  can limit the small size of the electronic device and/or the size of the display. 
     In one or more embodiments, the present invention can reduce the amount of space occupied by driver  18 , flex  20 , and flex-to-driver fan-out  28  and provide compact flex and driver sub-assemblies for electronic devices generally. 
       FIGS. 2A-2B  illustrate a compact flex and driver sub-assembly in accordance with a first embodiment of the present invention. Sub-assembly  30  can include driver  32 , flex  34 , flex-to-driver fan-out  36 , and driver-to-active area fan-out  38 , all of which can be disposed (at least in part) on driver ledge  40  of pixel activation substrate  42 , directly or indirectly. In one embodiment of the present invention, substrate  42  can be made of transparent, non-conductive material, e.g., glass. 
     To reduce the Y dimension of the driver ledge so that length Y 2  of ledge  40  is less than length Y 1  of ledge  24  of  FIG. 1 , the space on driver ledge  42  occupied by portions of flex  20  and fan-out  28  in conventional display assembly  10  can be reduced or eliminated. This can be accomplished by attaching multiple smaller attachment portions  44  of flex  34  to areas of substrate  42  that were unused in conventional display assembly  10 , instead of attaching the flex to the pixel activation substrate along the entire width of the flex as in  FIG. 1 . For example, in conventional display assembly  10  of  FIG. 1 , unused areas of substrate  12  can be located laterally adjacent to driver  18  in the X-axis, e.g., in-line with longitudinal axis L 1  of display driver  18 . To efficiently use this space, attachment portions  44  of flex  34  can be disposed on substrate  42  in those previously unoccupied areas, e.g., so that attachment portions  44  intersect longitudinal axis L 1  of driver  32 . As a result, flex  34  can form recess  46  between attachment portions  44  within which driver  32  can be disposed. 
     Wires of flex-to-driver fan-out  36  can emanate from a single edge of each attachment portion  44  (as in  FIG. 2A ) or from multiple edges of each attachment portion  44  (as in  FIG. 2B ). In the latter case, the wires in attachment portion  44  and fan-out  36  can terminate in staggered configurations, as described in greater detail below with respect to  FIGS. 7A-7C . The wires also can terminate along one or more edges of display driver  32 . Unlike the fan-out of conventional display assemblies in which all the wires are disposed in one-dimensional patterns, one or more wires of fan-out  36  can be configured in a multi-dimensional (e.g., 2-D or 3-D) pattern. Advantageously, the flexibility in the configuration of the wires of flex-to-driver fan-out  36  can permit the flex and display driver sub-assemblies to be designed more compactly. 
     As used herein, when a wire is disposed in a one-dimensional pattern, that wire has a linear configuration. That is, the wire is disposed on the substrate along one linear axis. When a wire is disposed in a 2-D pattern, the wire has a non-linear configuration. For example, as shown in  FIG. 2B , wire W is disposed on substrate  42  along both orthogonal X and Y axes. A wire also can be disposed in a 2-D pattern when it is disposed in two or more non-orthogonal directions. Likewise, a wire also can be disposed in a non-linear 3-D pattern. 
     Again, to efficiently use areas of the substrate that previously was unoccupied in conventional flex and driver sub-assemblies, portions of flex-to-driver fan-out  36  may be disposed in the same lateral space in the X-axis as driver-to-active area fan-out  38 . For example, in the illustrative embodiment shown in  FIGS. 2A-2B , no intervening components are disposed between the two fan-outs. Depending on the layout, the area occupied by driver-to-active area fan-out  38  and the configuration of wires in fan-out  38  may need to be adjusted to accommodate flex-to-driver fan-out  36 . 
     Because some of the wires of fan-out  36  have greater length than that of the wires of conventional flex-to-driver fan-outs, the longer wire-traces of fan-out  36  also may have greater impedance. To reduce the likelihood that the impedances of the wires of flex-to-driver fan-out  36  do not surpass the maximum specified impedance of the signals transmitted therethrough, one or more of the wires can have a greater cross-sectional area than that of conventional flex-to-driver fan-outs. More detailed discussion of this can be found below with respect to  FIG. 8 . To accommodate the greater cross-sectional area of one or more of the wires, flex-to-driver fan-out  36  can have a fewer number of wires as compared to that of fan-out  28  of conventional display assembly  10 . To transmit the same number and type of signals with fewer wires, the electronic device may employ a high speed serial interface, such as, for example, the Mobile Pixel Link physical layer offered by National Semiconductor Corporation of Santa Clara, Calif., the Mobile Display Digital Interface offered by Qualcomm Incorporated of San Diego, Calif., and the Mobile Industry Processor Interface (MIPI) promulgated by the MIPI Alliance. To further reduce the likelihood that the impedances of the wires of flex-to-driver fan-out  36  do not surpass the maximum specified impedance of the signals transmitted therethrough, the signals can be prioritized so that those requiring lower impedance wires can be transmitted through the wires having shorter length and/or larger cross-sectional area. 
     Pixel activation substrate  42  can include additional features to facilitate alignment of flex  34  and driver  32 . For example, to align flex  34 , an optical registration camera (not shown) can be placed underneath substrate  42  and used to provide feedback as to the alignment of one or more registration marks on the substrate with one or more registration marks on the flex. Similarly, to align driver  32 , the optical registration camera can provide feedback as to the alignment of one or more registration marks on the substrate with one or more registration marks on the driver. The optical registration camera also can be used to provide feedback as to the alignment of wires on the flex with those of fan-out  36 , and/or the alignment of electrical contacts of driver  32  with the wires of fan-out  36 . 
       FIG. 3  illustrates a compact flex and driver sub-assembly in accordance with a second embodiment of the present invention. Flex and driver sub-assembly  50  can include driver  52 , flex  54 , flex-to-driver fan-out  56 , and driver-to-active area fan-out  58 , all of which can be disposed (at least in part) on driver ledge  60  of pixel activation substrate  62 , directly or indirectly. 
     To reduce the space within the electronic device that is occupied by flex  54 , flex  54  can have a maximum width that is less than that of flex  20  of  FIG. 1  and driver  52  (i.e., maximum width X 54  of flex  54  can be less than width X 52  of driver  52 ). Because flex  54  has a smaller width, the area of flex  54  that can be attached to pixel activation substrate  62  also can be smaller. As a result, flex  54  may not be able to accommodate as many wires. Again, a high speed serial interface may be employed to permit all desired signals to be transmitted using fewer wires. Composite wires, such as those described below with respect to  FIGS. 9B-9D , also can be used to accommodate the reduction in the number of wires. Also, to reduce the likelihood that the impedances of the wires of flex-to-driver fan-out  56  do not surpass the maximum specified impedance of the signals transmitted therethrough, the wires of fan-out  56  can have an increased cross-sectional area and signals can be prioritized so that those requiring lower impedance wires can be transmitted through the wires having shorter length and/or greater cross-sectional area. 
     As with flex-to-driver fan-out  36  of  FIGS. 2A-2B , the wires of flex-to-driver fan-out  56  can emanate from a single edge of flex  54  or from multiple edges of flex  54 . Some wires of fan-out  56  can have the same uniform length and be disposed in a parallel one-dimensional pattern between driver  52  and flex  54 . These wires can transmit, for example, signals that require transmission along lower impedance lines. Other wires can have non-uniform lengths and be disposed in 2-D patterns. These wires can transmit, for example, signals that permit transmission through higher impedance lines. Again, the flexibility in the configuration of the wires of flex-to-driver fan-out  56  can permit flex and driver sub-assemblies to be designed to be more compact. 
     To reduce the Y dimension of the driver ledge so that length Y 3  of ledge  60  is less than length Y 1  of ledge  24  of  FIG. 1 , one or more wires of flex-to-driver fan-out  56  can be routed underneath display driver  52  when the driver is disposed on substrate  62 . Thus, at least one wire trace is disposed in an area of the substrate on which display driver  52  is to be disposed, rather than occupying additional space on substrate  62  in the X-Y plane. Depending on the height of the wires of fan-out  56 , the wires disposed underneath driver  52  may not appreciably increase the height by which the driver is offset from substrate  62 . Wires routed underneath driver  52  can transmit any type of power and data signals, so long as the resistance of the wires do not exceed the maximum impedance for which the signals are specified. In one embodiment of the present invention, wires routed underneath the driver can transmit power signals and/or serve as a ground potential. 
       FIG. 4  illustrates a compact flex and driver sub-assembly in accordance with a third embodiment of the present invention. Flex and driver sub-assembly  70  can include driver  72 , flex  74 , flex-to-driver fan-out  76 , and driver-to-active area fan-out  78  disposed on driver ledge  80  of pixel activation substrate  82 , directly or indirectly. 
     Sub-assembly  70  can be a combination of sub-assemblies  30  and  50 . For example, flex  74  can have maximum width X 74  that is less than width X 72  of driver  72 . Because flex  74  is narrower, the attachment portion of flex  74  for attaching the flex to substrate  82  also may be smaller. This can permit flex  74  to be attached to previously unused portions of substrate  82 . For example, flex  74  can be attached to substrate  72  so that the flex intersects the longitudinal axis of driver  72 . 
     Flex-to-driver fan-out  76  also can be configured similarly to those of sub-assemblies  30  and  50 . Flex-to-driver fan-out  76  can have wires that emanate from one or multiple edges of flex  74 . The wires also can terminate along one or multiple edges of display driver  72 . One or more wires of fan-out  76  also can be disposed on substrate  82  in the same area on which display driver  72  is disposed. That is, wires can be disposed on substrate  82  underneath display driver  72 . To accommodate signals that require transmission along lower impedance lines, some wires of fan-out  76  can have the same uniform length and be disposed in parallel one-dimensional patterns between driver  72  and flex  74 . Fan-out  76  also can have one or more wires that are disposed in two-dimensional patterns. One or more two-dimensional wires in flex-to-driver fan-out  76  can be disposed adjacent to driver-to-active area fan-out  78  in the X-axis. 
       FIG. 5  illustrates a compact flex and driver sub-assembly in accordance with a fourth embodiment of the present invention. Flex and driver sub-assembly  90  can be similar to sub-assembly  70  of  FIG. 4  except that maximum width X 94  of flex  94  attached to substrate  102  can be greater than that of flex  72 , while still being less than width X 92  of display driver  92 . The added width can permit flex-to-driver fan-out  96  to incorporate additional wires for transmission of signals between driver  92  and flex  94 . This can permit an electronic device incorporating sub-assembly  90  to employ either a parallel or serial data transmission interface as desired. Furthermore, the additional wires can have shorter length and be disposed in parallel one-dimensional patterns between the display driver and the flex. This can permit fan-out  96  to accommodate more signals requiring transmission through lower impedance lines. 
       FIG. 6  illustrates a compact flex and driver sub-assembly in accordance with a fifth embodiment of the present invention. Flex and driver sub-assembly  110  can be similar to sub-assembly  30  of  FIGS. 2A-2B  except that the mid-span of flex  34  can be eliminated to reduce the space occupied by the flex. Accordingly, sub-assembly  110  can have two flexes  114  and  116 , each of which can be attached to substrate  126  at previously unoccupied areas of the substrate. Flex-to-driver fan-outs  118 ,  120  can be disposed on substrate  126  (directly or indirectly) to operatively couple each flex  114 ,  116  to driver  112 . Each flex  114 ,  116  also can have board-to-board connector  122 ,  124  for operatively coupling each flex to a circuit board (not shown) of the electronic device. 
       FIGS. 7A-7C  illustrate a staggered wire pattern in accordance with one embodiment of the present invention. Flex  130  can be configured to be operatively coupled to side-connecting flex-to-driver fan-out  139 . That is, side-connecting flex-to-driver fan-out  139  can have at least one wire that emanates from flex  130  in a direction that is not parallel to the longitudinal axis L 2  or co-linear with the wires of flex  130  at or near the regions in which fan-out  139  connects to flex  130 . For example, fan-out  139  can have at least one wire that emanates from flex  130  in an orthogonal direction. 
     Flex  130  can include a substrate on which a set of wires  132 ,  134  are disposed, directly or indirectly. Each wire  132 ,  134  can have at least two termination regions, one disposed at one end of flex  130  and another disposed at the other end of flex  130 . One or more electrical contacts can be positioned at each termination region, as discussed in greater detail below with respect to  FIGS. 9B-9D . The electrical contacts can operatively couple flex  130  to other electrical components, e.g., the wires of a flex-to-driver fan-out or another circuit board, either directly or indirectly. 
       FIGS. 7A-7C  illustrate the end of flex  130  that is configured for coupling to pixel activation substrate  136  of a display assembly. Wires  134  of flex  130  can have electrical contacts disposed in a staggered configuration, whereas wires  132  of flex  130  can have electrical contacts disposed in a non-staggered configuration. 
     Substrate  136  can have flex-to-driver fan-out  139  with wires disposed in a pattern that complements wires  132 ,  134  of flex  130 . That is, the electrical contacts of flex-to-driver fan-out  139  can be disposed on substrate  136  in positions that complement the positions at which the electrical contacts of wires  132 ,  134  are disposed. For example, the electrical contacts of wires  142  of flex-to-driver fan-out  139  can be disposed in a complementary staggered configuration, whereas the electrical contacts of wires  140  of the fan-out can be disposed in a complementary non-staggered configuration. Electrical contacts disposed at the other ends or termination regions of wires  140 ,  142  can be operatively coupled to electrical contacts on driver  138 . 
     Advantageously, the staggered configurations of wires  134 ,  142  can facilitate connection of a flex to a fan-out when the wires of the fan-out are not disposed co-linearly with the wires of the flex near the regions in which the two components connect. For example, as shown in  FIGS. 7A-7C , the staggered configurations can facilitate connection of a flex having wires that are disposed orthogonal to the wires of flex-to-driver fan-out  139 . While  FIGS. 7A-7C  illustrate flex  130  and flex-to-driver fan-out  139  as having wires with electrical contacts disposed in both staggered and non-staggered configurations, flex  130  and flex-to-driver fan-out  139  also can have wire electrical contacts that are disposed only in staggered configurations. 
       FIG. 8  illustrates a wire pattern in accordance with one embodiment of the present invention. Fan-out  150  can include wires designed to accommodate (1) the maximum specified impedance for the signals transmitted through the wires, and (2) the surface area available for disposition of fan-out  150  on pixel activation substrate  152 . To accommodate these factors, the wires of fan-out  150  can have widths that vary from wire to wire and/or that vary along the same wire. 
     The resistance of a wire can be determined based on the following equation: 
                   R   =       ρ   ⁢           ⁢   L     A             EQ   .           ⁢   1               
where ρ represents the resistivity of the wire material, L is the length of the wire, and A is the cross-sectional area of the wire. Thus, by varying any one of these variables, e.g., the length or cross-sectional area of a wire, the resistance of the wire also can be varied.
 
     As shown in  FIG. 8 , fan-out  150  can include wires having widths that vary from wire to wire. It may be desirable to design wires to be of narrower widths when the signals transmitted on the wires do not need to travel a long distance from a flex to driver  154  and/or the narrower widths can still accommodate the maximum specified impedances of the signals transmitted along the wires. Similarly, it may be desirable to design wires to be of wider widths when the signals transmitted on the wires need to travel a long distance from the flex to the driver and/or the wider widths are needed to accommodate the maximum specified impedances of the signals transmitted along the wires. Since one or more embodiments of the present invention can include flex-to-driver fan-out wires having variable lengths, the wires of those embodiments can have widths that vary from wire to wire. 
     Also shown in  FIG. 8 , fan-out  150  can include wires having widths that vary along the same wire. For example, each wire A-C has a width that varies along the length of the wire. When there is more space available on substrate  152  for the wires to be disposed, the width of wires A-C can be wider. However, when there is less space available (e.g., due to the size of driver  154  or the layout of components on substrate  152 ), the width of the wires can be reduced. Advantageously, the resulting variable width wires can have smaller effective resistances than those of wires having a constant width limited by the space available at only certain portions of the wires. 
       FIG. 9A  illustrates prior art wires used in conventional flex and driver sub-assemblies, such as sub-assembly  10  of  FIGS. 1A-1B . Each of prior art wires  160 ,  162  can have electrical contact  164 ,  166  disposed at the end of the wire for coupling to another electronic device. Adjacent wires  160 ,  162  can be separated by distance t. Typically, each wire  160 ,  162  can have the same nominal cross-sectional shape with the same nominal height and width T. Each wire  160 ,  162  also can have the same nominal length and resistivity, thereby resulting in the same nominal resistance (R NOM ). In some conventional flex and fan-out designs, both prior art wires  160 ,  162  may be used to transmit the same power or data signal. As described in greater detail below, however, the use of two identical wires to transmit the same signals can be less efficient than one or more embodiments of the present invention. 
       FIGS. 9B-9D  show illustrative composite wires in accordance with one or more embodiments of the present invention. Composite wires  170  can be similar to prior art wires  160 ,  162 , except that each composite wire  170  can transmit the same energy flux as multiple prior art wires  160 ,  162  with less resistance. For example, each composite wire  170  can have twice the width (2T) of prior art wire  160  or  162 . All other factors being nominally the same, the nominal resistance of composite wire  170  can be half that of either prior art wire  160  or  162  (i.e., R NOM /2). Furthermore, composite wire  170  can occupy less space than that occupied by prior art wires  160 ,  162  in total (i.e., 2T v. 2T+t). Thus, in flexes and fan-outs in which prior art wires  160 ,  162  are used to transmit the same power or data signal, the prior art wires can be replaced with composite wires  170  for more efficient use of space and/or for less resistance. For example, composite wire  170  can be used to transmit signals for a longer distance with less than or equal to the resistance of prior art wires  160 ,  162 . Furthermore, because less space is occupied by composite wire  170 , flexes can be narrower and less space can be occupied by fan-outs. 
     In the embodiments illustrated in  FIGS. 9B-9D , each composite wire  170  can have multiple electrical contacts disposed at the end of each wire to emulate the electrical contacts from multiple prior art wires. Each electrical contact can be coupled to a complementary electrical contact on an electronic component, using, e.g., anisotropic conductive films. Electrical contacts  172 - 176  can be arranged in a side-by-side orientation as in  FIG. 9B , a stacked orientation as in  FIG. 9C , in a staggered orientation as in  FIG. 9D , or any combination thereof. 
       FIG. 10  shows illustrative electronic devices in which flex and driver sub-assemblies of the present invention can be incorporated. For example, the sub-assemblies of the present invention can be incorporated in media player/recorder  130 , cellular telephone  140 , touch-sensitive electronic device  150 , or any combination thereof. Media player/recorder  130  can have a display and playback audio and visual data. One example of a media player/recorder is a portable media player similar to that sold under the trademark iPod™ by Apple Computer, Inc. of Cupertino, Calif. Touch-sensitive electronic device  150  can include electronic devices that can accept user input by sensing the touch or proximity of a user&#39;s body part, a stylus, or a digital pen through, e.g., a touch-sensitive display. Touch sensitive electronic device  150  can include, for example, personal digital assistants, hand-held gaming devices, laptop computers, or tablet PCs. 
     The present invention also can be incorporated in any electronic device in which a compact flex and driver sub-assembly may be desirable. For example, the electronic device can be any portable, mobile, hand-held, or miniature consumer electronic device. Illustrative electronic devices can include, but are not limited to, music players, video players, still image players, game players, other media players, music recorders, video recorders, cameras, other media recorders, radios, medical equipment, calculators, cellular phones, other wireless communication devices, personal digital assistants, programmable remote controls, pagers, laptop computers, printers, or any combination thereof. Miniature electronic devices may have a form factor that is smaller than that of hand-held devices. Illustrative miniature electronic devices can include, but are not limited to, watches, rings, necklaces, belts, accessories for belts, headsets, accessories for shoes, virtual reality devices, other wearable electronics, accessories for sporting equipment, accessories for fitness equipment, key chains, or any combination thereof. 
     Although particular embodiments of the present invention have been described above in detail, it will be understood that this description is merely for purposes of illustration. Alternative embodiments of those described hereinabove also are within the scope of the present invention. 
     Combinations of the above-described embodiments of the present invention or portions thereof may be provided in one electronic device unit. For example, while  FIG. 3  illustrates a display assembly having wires routed underneath the display driver, other embodiments of the present invention, such as the assemblies of  FIGS. 2A-2B , also can have similarly routed wires. 
     While the above described embodiments have illustrated the flex and driver sub-assemblies of the present invention in the context of display assemblies, the principles of the present invention also can be applied to flex and driver sub-assemblies in any device or context. 
     The above described embodiments of the present invention are presented for purposes of illustration and not of limitation, and the present invention is limited only by the claims which follow.

Metadata:
Filing Date: 20070105
Publication Date: 20110510
Grant Date: 20110510
Priority Date: 20070105
Inventors: GETTEMY SHAWN ROBERT
YAO WEI
CORLETT BARRY
Assignee: APPLE INC
CPC Classifications: [{"code": "Y10T29/4913", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K1/147", "inventive": true, "first": true, "tree": "[]"}, {"code": "H05K2201/09227", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/1345", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K2201/10674", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K2201/09145", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K1/181", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 39593304