PATENT DOCUMENT

Publication Number: US-10852876-B2
Application Number: US-201415313942-A
Country: US
Kind Code: B2

Title: Narrow border touch screen

Abstract:
A touch screen is disclosed that includes conductive elements in a display area and connecting traces for routing the conductive elements to other locations. The connecting traces can be routed underneath or over existing opaque structures in the display area, instead of in border areas adjacent to the display area, to minimize the effect of the connecting traces on the display aperture ratio. The lengths and/or widths of these connecting traces as well as the number of parallel connecting traces used to connect to a particular element can be selected to balance the load on the drive and/or sense circuitry and on display pixels caused by the connecting traces.

Claims:
The invention claimed is: 
     
       1. A touch screen comprising:
 a data layer; 
 a plurality of electrodes formed in a display area of the touch screen, wherein the plurality of electrodes are configured to operate as at least touch-sensing electrodes; and 
 a plurality of connecting touch-sensing traces coupled to the plurality of electrodes and routed in the display area, wherein the plurality of connecting touch-sensing traces are configured to at least carry one or more signals between the plurality of electrodes and touch circuitry; 
 wherein:
 at least one of the plurality of connecting touch-sensing traces is routed under a data line in the data layer that is configured to control a luminance of a display pixel, the data line disposed between the at least one of the plurality of connecting touch-sensing traces and an electrode of the plurality of electrodes to which the at least one connecting touch-sensing trace is coupled, wherein the electrode of the plurality of electrodes is electrically coupled to the at least one connecting touch-sensing trace using at least one via that is in contact with the at least one connecting touch-sensing trace. 
 
 
     
     
       2. The touch screen of  claim 1 , wherein one or more first connecting touch-sensing traces coupled to a first electrode are configured such that a total resistance of the one or more first connecting touch-sensing traces substantially matches a total resistance of one or more second connecting touch-sensing traces coupled to a second electrode. 
     
     
       3. The touch screen of  claim 2 , wherein a length of the one or more first connecting touch-sensing traces is selected such that the total resistance of the one or more first connecting touch-sensing traces substantially matches the total resistance of the one or more second connecting touch-sensing traces. 
     
     
       4. The touch screen of  claim 2 , wherein a width of the one or more first connecting touch-sensing traces is selected such that the total resistance of the one or more first connecting touch-sensing traces substantially matches the total resistance of the one or more second connecting touch-sensing traces. 
     
     
       5. The touch screen of  claim 1 , wherein one or more first connecting touch-sensing traces coupled to a first electrode are configured such that a total capacitance of the one or more first connecting touch-sensing traces substantially matches a total capacitance of one or more second connecting touch-sensing traces coupled to a second electrode. 
     
     
       6. The touch screen of  claim 5 , further comprising a trace extension coupled to each of the one or more first connecting touch-sensing traces, the trace extensions configured such that the total capacitance of the one or more first connecting touch-sensing traces substantially matches the total capacitance of the one or more second connecting touch-sensing traces. 
     
     
       7. The touch screen of  claim 6 , wherein a length of the trace extensions is selected such that the total capacitance of the one or more first connecting touch-sensing traces substantially matches the total capacitance of the one or more second connecting touch-sensing traces. 
     
     
       8. The touch screen of  claim 6 , wherein a width of the trace extensions is selected such that the total capacitance of the one or more first connecting touch-sensing traces substantially matches the total capacitance of the one or more second connecting touch-sensing traces. 
     
     
       9. The touch screen of  claim 1 :
 wherein each of the plurality of electrodes is formed from a plurality of display pixel stackups; and 
 wherein the plurality of connecting touch-sensing traces are configured to equalize an effect of the connecting touch-sensing traces on the plurality of display pixel stackups. 
 
     
     
       10. The touch screen of  claim 1 , further comprising:
 a gate layer including one or more gate lines that are configured to control operation of one or more pixel transistors in the touch screen; and 
 a connecting trace layer formed between the data layer and the gate layer; 
 wherein the plurality of connecting touch-sensing traces are formed in the connecting trace layer. 
 
     
     
       11. The touch screen of  claim 1 , wherein at least one of the plurality of connecting touch-sensing traces is routed under an opaque area of the display area. 
     
     
       12. A method of forming a touch screen comprising:
 routing a plurality of electrodes formed in a display area of the touch screen to a second area using a plurality of connecting touch-sensing traces routed in the display area, wherein the plurality of electrodes are configured to operate as at least touch-sensing electrodes, and wherein the plurality of connecting touch-sensing traces are configured to at least carry one or more signals between the plurality of electrodes and touch circuitry; and 
 routing at least one of the plurality of connecting touch-sensing traces under a data line in a data layer that is configured to control a luminance of a display pixel, the data line disposed between the at least one of the plurality of connecting touch-sensing traces and an electrode of the plurality of electrodes to which the at least one connecting touch-sensing trace is coupled, wherein the electrode of the plurality of electrodes is electrically coupled to the at least one connecting touch-sensing trace using at least one via that is in contact with the at least one connecting touch-sensing trace. 
 
     
     
       13. The method of  claim 12 , further comprising matching a total resistance of one or more first connecting touch-sensing traces coupled to a first electrode with a total resistance of one or more second connecting touch-sensing traces coupled to a second electrode. 
     
     
       14. The method of  claim 13 , further comprising selecting a length of the one or more first connecting touch-sensing traces such that the total resistance of the one or more first connecting touch-sensing traces substantially matches the total resistance of the one or more second connecting touch-sensing traces. 
     
     
       15. The method of  claim 13 , further comprising selecting a width of the one or more first connecting touch-sensing traces such that the total resistance of the one or more first connecting touch-sensing traces substantially matches the total resistance of the one or more second connecting touch-sensing traces. 
     
     
       16. The method of  claim 12 , further comprising matching a total capacitance of one or more first connecting touch-sensing traces coupled to a first electrode with a total capacitance of one or more second connecting touch-sensing traces coupled to a second electrode. 
     
     
       17. The method of  claim 16 , further comprising extending each of the one or more first connecting touch-sensing traces such that the total capacitance of the one or more first connecting touch-sensing traces substantially matches the total capacitance of the one or more second connecting touch-sensing traces. 
     
     
       18. The method of  claim 17 , further comprising selecting a length of the trace extensions such that the total capacitance of the one or more first connecting touch-sensing traces substantially matches the total capacitance of the one or more second connecting touch-sensing traces. 
     
     
       19. The method of  claim 17 , further comprising selecting a width of the trace extensions such that the total capacitance of the one or more first connecting touch-sensing traces substantially matches the total capacitance of the one or more second connecting touch-sensing traces. 
     
     
       20. The method of  claim 12 , further comprising:
 forming each of the plurality of electrodes from a plurality of display pixel stackups; and 
 forming the connecting touch-sensing traces to equalize an effect of the connecting touch-sensing traces on the plurality of display pixel stackups. 
 
     
     
       21. The method of  claim 12 , further comprising forming the plurality of connecting touch-sensing traces between the data layer and a gate layer including one or more gate lines that are configured to control operation of one or more pixel transistors in the touch screen. 
     
     
       22. The method of  claim 12 , further comprising routing at least one of the plurality of connecting touch-sensing traces under an opaque area of the display area. 
     
     
       23. The touch screen of  claim 1 , wherein the plurality of electrodes are configured to operate as at least display electrodes. 
     
     
       24. The touch screen of  claim 1 , wherein the plurality of connecting touch-sensing traces are formed of non-transparent materials.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application is a National Phase application under 35 U.S.C. § 371 of International Application No. PCT/US2014/057032, filed Sep. 23, 2014, which claims priority to U.S. Provisional Patent Application No. 62/004,093, filed May 28, 2014, the contents of which are hereby incorporated by references in their entirety for all intended purposes. 
    
    
     FIELD OF THE DISCLOSURE 
     This relates generally to touch screens, and more particularly, to touch screens in which connecting traces for elements in an active area of the touch screen are routed in the active area rather than in a border area in order to narrow the border area of the touch screen. 
     BACKGROUND OF THE DISCLOSURE 
     Many types of input devices are presently available for performing operations in a computing system, such as buttons or keys, mice, trackballs, joysticks, touch sensor panels, touch screens and the like. Touch screens, in particular, are becoming increasingly popular because of their ease and versatility of operation as well as their declining price. Touch screens can include a touch sensor panel, which can be a clear panel with a touch-sensitive surface, and a display device such as a liquid crystal display (LCD) that can be positioned partially or fully behind the panel or integrated with the panel so that the touch-sensitive surface can cover at least a portion of the viewable area of the display device. Touch screens can allow a user to perform various functions by touching the touch sensor panel using a finger, stylus or other object at a location often dictated by a user interface (UI) being displayed by the display device. In general, touch screens can recognize a touch and the position of the touch on the touch sensor panel, and the computing system can then interpret the touch in accordance with the display appearing at the time of the touch, and thereafter can perform one or more actions based on the touch. In the case of some touch sensing systems, a physical touch on the display is not needed to detect a touch. For example, in some capacitive-type touch sensing systems, fringing electrical fields used to detect touch can extend beyond the surface of the display, and objects approaching near the surface may be detected near the surface without actually touching the surface. 
     Capacitive touch sensor panels can be formed by a matrix of substantially transparent conductive elements made of materials such as Indium Tin Oxide (ITO). It is due in part to their substantial transparency that capacitive touch sensor panels can be overlaid on a display to form a touch screen, as described above. In addition, some touch screens can be formed by partially integrating touch sensing circuitry into a display pixel stackup (i.e., the stacked material layers forming the display pixels). Some elements in an active area (the display area) of the touch screen may need to be routed to particular edges of the touch screen using connecting traces in order to provide for off-panel or other connections. However, routing these connecting traces in opaque border areas of the touch screen may cause these border areas to be wide, which can reduce the optical aperture of the touch screen. 
     SUMMARY OF THE DISCLOSURE 
     Some capacitive touch sensor panels can be formed as a matrix of substantially transparent conductive elements made of material such as Indium Tin Oxide (ITO), and some touch screens can be formed by partially integrating touch sensing circuitry into a display pixel stackup (i.e., the stacked material layers forming the display pixels). The conductive elements can be electrically connected to drive and/or sense circuitry using connecting traces. 
     In some examples of the disclosure, the connecting traces can be routed underneath or over existing structures in an active area of the display, instead of in border areas adjacent to the active area of the display, to minimize the effect of the connecting traces on the display aperture ratio. The lengths and/or widths of these connecting traces as well as the number of parallel connecting traces used to connect to a particular element can be selected to balance the load on the drive and/or sense circuitry and on display pixels caused by the connecting traces. The connecting traces can be formed in a separate conductive material layer, and can be connected to the elements through vias in a separate insulating layer. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A-1C  illustrate an example mobile telephone, an example media player, and an example portable computing device that can each include an exemplary touch screen according to examples of the disclosure. 
         FIG. 2  is a block diagram of an exemplary computing system that illustrates one implementation of an example touch screen according to some examples of the disclosure. 
         FIG. 3  illustrates an exemplary touch sensor circuit corresponding to a self-capacitance touch pixel electrode and sensing circuit according to some examples of the disclosure. 
         FIG. 4  illustrates an example configuration in which common electrodes can form portions of the touch sensing circuitry of a touch sensing system according to some examples of the disclosure. 
         FIG. 5  illustrates an exemplary touch screen display with connecting traces routed in the border area according to some examples of the disclosure. 
         FIG. 6  illustrates another exemplary touch screen display with connecting traces routed in the active area according to some examples of the disclosure. 
         FIG. 7  illustrates a top view of an exemplary stackup of superimposed layers of a pixel layout according to some examples of the disclosure. 
         FIG. 8  illustrates a top view of an exemplary connection architecture according to some examples of the disclosure. 
         FIG. 9  illustrates an exemplary cross-section of an active area of a touch screen according to some examples of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description of examples, reference is made to the accompanying drawings which form a part hereof, and in which it is shown by way of illustration specific examples that can be practiced. It is to be understood that other examples can be used and structural changes can be made without departing from the scope of the disclosed examples. 
     Some capacitive touch sensor panels can be formed as a matrix of substantially transparent conductive elements made of material such as Indium Tin Oxide (ITO), and some touch screens can be formed by partially integrating touch sensing circuitry into a display pixel stackup (i.e., the stacked material layers forming the display pixels). The conductive elements can be electrically connected to drive and/or sense circuitry using connecting traces. 
     In some examples of the disclosure, the connecting traces can be routed underneath or over existing structures in an active area of the display, instead of in border areas adjacent to the active area of the display, to minimize the effect of the connecting traces on the display aperture ratio. The lengths and/or widths of these connecting traces as well as the number of parallel connecting traces used to connect to a particular element can be selected to balance the load on the drive and/or sense circuitry and on display pixels caused by the connecting traces. The connecting traces can be formed in a separate conductive material layer, and can be connected to the elements through vias in a separate insulating layer. 
       FIGS. 1A-1C  show example systems in which a touch screen according to examples of the disclosure may be implemented.  FIG. 1A  illustrates an example mobile telephone  136  that includes a touch screen  124 .  FIG. 1B  illustrates an example digital media player  140  that includes a touch screen  126 .  FIG. 1C  illustrates an example portable computing device  144  that includes a touch screen  128 . It is understood that the above touch screens can be implemented in other devices as well, including in wearable devices. 
     Touch screens  124 ,  126  and  128  can be based on self-capacitance or mutual capacitance. A self-capacitance based touch system can include small plates of conductive material that can be referred to as touch pixels or touch pixel electrodes. During operation, the touch pixel can be stimulated with an AC waveform and the self-capacitance of the touch pixel can be measured. As an object approaches the touch pixel, the self-capacitance of the touch pixel can change. This change in the self-capacitance of the touch pixel can be detected and measured by the touch sensing system to determine the positions of multiple objects when they touch, or come in proximity to, the touch screen. 
     A mutual capacitance based touch system can include drive and sense lines that may cross over each other on different layers, or may be adjacent to each other on the same layer. The crossing or adjacent locations can be referred to as touch pixels or touch pixel electrodes. During operation, the drive line can be stimulated with an AC waveform and the mutual capacitance of the touch pixel can be measured. As an object approaches the touch pixel, the mutual capacitance of the touch pixel can change. This change in the mutual capacitance of the touch pixel can be detected and measured by the touch sensing system to determine the positions of multiple objects when they touch, or come in proximity to, the touch screen. In some examples, a touch screen can be multi-touch, single touch, projection scan, full-imaging multi-touch, capacitive touch, etc. 
       FIG. 2  is a block diagram of an example computing system  200  that illustrates one self-capacitance implementation of an example touch screen  220  according to examples of the disclosure, although it should be understood that a mutual capacitance computing system could be employed as well. Computing system  200  can be included in, for example, mobile telephone  136 , digital media player  140 , portable computing device  144 , or any mobile or non-mobile computing device that includes a touch screen, including a wearable device. Computing system  200  can include a touch sensing system including one or more touch processors  202 , peripherals  204 , a touch controller  206 , and touch sensing circuitry (described in more detail below). Peripherals  204  can include, but are not limited to, random access memory (RAM) or other types of memory or storage, watchdog timers and the like. Touch controller  206  can include, but is not limited to, one or more sense channels  208  and channel scan logic  210 . Channel scan logic  210  can access RAM  212 , autonomously read data from sense channels  208  and provide control for the sense channels. In addition, channel scan logic  210  can control sense channels  208  to generate stimulation signals at various frequencies and phases that can be selectively applied to the touch pixels of touch screen  220 , as described in more detail below. In some examples, touch controller  206 , touch processor  202  and peripherals  204  can be integrated into a single application specific integrated circuit (ASIC), and in some examples can be integrated with touch screen  220  itself. 
     Touch screen  220  can include touch sensing circuitry that can include a capacitive sensing medium having a plurality of touch pixels  222 . Touch pixels  222  can be coupled to sense channels  208  in touch controller  206 , can be driven by stimulation signals from the sense channels through drive/sense interface  225 , and can be sensed by the sense channels through the drive/sense interface as well, as described above. Labeling the conductive plates used to detect touch (i.e., touch pixels  222 ) as “touch pixels” can be particularly useful when touch screen  220  is viewed as capturing an “image” of touch. In other words, after touch controller  206  has determined an amount of touch detected at each touch pixel  222  in touch screen  220 , the pattern of touch pixels in the touch screen at which a touch occurred can be thought of as an “image” of touch (e.g., a pattern of fingers touching the touch screen). 
     Computing system  200  can also include a host processor  228  for receiving outputs from touch processor  202  and performing actions based on the outputs. For example, host processor  228  can be connected to program storage  232  and a display controller, such as an LCD driver  234 . The LCD driver  234  can provide voltages on select (gate) lines to each pixel transistor and can provide data signals along data lines to these same transistors to control the pixel display image as described in more detail below. Host processor  228  can use LCD driver  234  to generate an image on touch screen  220 , such as an image of a user interface (UI), and can use touch processor  202  and touch controller  206  to detect a touch on or near touch screen  220 . The touch input can be used by computer programs stored in program storage  232  to perform actions that can include, but are not limited to, moving an object such as a cursor or pointer, scrolling or panning, adjusting control settings, opening a file or document, viewing a menu, making a selection, executing instructions, operating a peripheral device connected to the host device, answering a telephone call, placing a telephone call, terminating a telephone call, changing the volume or audio settings, storing information related to telephone communications such as addresses, frequently dialed numbers, received calls, missed calls, logging onto a computer or a computer network, permitting authorized individuals access to restricted areas of the computer or computer network, loading a user profile associated with a user&#39;s preferred arrangement of the computer desktop, permitting access to web content, launching a particular program, encrypting or decoding a message, and/or the like. Host processor  228  can also perform additional functions that may not be related to touch processing. 
     Note that one or more of the functions described above, including the configuration of switches, can be performed by firmware stored in memory (e.g., one of the peripherals  204  in  FIG. 2 ) and executed by touch processor  202 , or stored in program storage  232  and executed by host processor  228 . The firmware can also be stored and/or transported within any non-transitory computer-readable storage medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processor-containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. In the context of this document, a “non-transitory computer-readable storage medium” can be any medium (excluding signals) that can contain or store the program for use by or in connection with the instruction execution system, apparatus, or device. The computer-readable storage medium can include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus or device, a portable computer diskette (magnetic), a random access memory (RAM) (magnetic), a read-only memory (ROM) (magnetic), an erasable programmable read-only memory (EPROM) (magnetic), a portable optical disc such a CD, CD-R, CD-RW, DVD, DVD-R, or DVD-RW, or flash memory such as compact flash cards, secured digital cards, USB memory devices, memory sticks, and the like. 
     The firmware can also be propagated within any transport medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processor-containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. In the context of this document, a “transport medium” can be any medium that can communicate, propagate or transport the program for use by or in connection with the instruction execution system, apparatus, or device. The transport medium can include, but is not limited to, an electronic, magnetic, optical, electromagnetic or infrared wired or wireless propagation medium. 
       FIG. 3  illustrates an exemplary touch sensor circuit  300  corresponding to a self-capacitance touch pixel electrode  302  and sensing circuit  314  according to examples of the disclosure, although it should be understood that a mutual capacitance touch pixel and sensing circuit could be employed as well. Touch pixel electrode  302  can correspond to touch pixel  222 . Touch pixel electrode  302  can have an inherent self-capacitance to ground associated with it, and also an additional self-capacitance to ground that is formed when an object, such as finger  305 , is in proximity to or touching the electrode. The total self-capacitance to ground of touch pixel electrode  302  can be illustrated as capacitance  304 . Touch pixel electrode  302  can be coupled to sensing circuit  314 . Sensing circuit  314  can include an operational amplifier  308 , feedback resistor  312 , feedback capacitor  310  and an input voltage source  306 , although other configurations can be employed. For example, feedback resistor  312  can be replaced by a switched capacitor resistor in order to minimize any parasitic capacitance effect caused by a variable feedback resistor. Touch pixel electrode  302  can be coupled to the inverting input of operational amplifier  308 . An AC voltage source  306  (Vac) can be coupled to the non-inverting input of operational amplifier  308 . Touch sensor circuit  300  can be configured to sense changes in the total self-capacitance  304  of the touch pixel electrode  302  induced by a finger or object either touching or in proximity to the touch sensor panel. Output  320  can be used by a processor to determine the presence of a proximity or touch event, or the output can be inputted into a discrete logic network to determine the presence of a touch or proximity event. 
     Referring back to  FIG. 2 , in some examples, touch screen  220  can be an integrated touch screen in which touch sensing circuit elements of the touch sensing system can be integrated into the display pixel stackups of a display, although it should be understood that non-integrated touch screens could be employed as well. The circuit elements in touch screen  220  can include, for example, elements that can exist in LCD or other displays, such as one or more pixel transistors (e.g., thin film transistors (TFTs)), gate lines, data lines, pixel electrodes and common electrodes. In any given display pixel, a voltage between a pixel electrode and a common electrode can control a luminance of the display pixel. The voltage on the pixel electrode can be supplied by a data line through a pixel transistor, which can be controlled by a gate line. It is noted that circuit elements are not limited to whole circuit components, such as a whole capacitor, a whole transistor, etc., but can include portions of circuitry, such as only one of the two plates of a parallel plate capacitor.  FIG. 4  illustrates an example configuration in which common electrodes  402  can form portions of the touch sensing circuitry of a touch sensing system—in some examples of this disclosure, the common electrodes can form touch pixels used to detect an image of touch on touch screen  400 , as described above. Each common electrode  402  (i.e., touch pixel) can include a plurality of display pixels  401 , and each display pixel  401  can include a portion of a common electrode  402 , which can be a circuit element of the display system circuitry in the pixel stackup (i.e., the stacked material layers forming the display pixels) of the display pixels of some types of LCD or other displays that can operate as part of the display system to display an image. 
     In the example shown in  FIG. 4 , each common electrode  402  can serve as a multi-function circuit element that can operate as display circuitry of the display system of touch screen  400  and can also operate as touch sensing circuitry of the touch sensing system. In this example, each common electrode  402  can operate as a common electrode of the display circuitry of the touch screen  400 , as described above, and can also operate as touch sensing circuitry of the touch screen. For example, a common electrode  402  can operate as a capacitive part of a touch pixel of the touch sensing circuitry during the touch sensing phase. Other circuit elements of touch screen  400  can form part of the touch sensing circuitry by, for example, switching electrical connections, etc. More specifically, in some examples, during the touch sensing phase, a gate line can be connected to a power supply, such as a charge pump, that can apply a voltage to maintain TFTs in display pixels included in a touch pixel in an “off” state. Stimulation signals can be applied to common electrode  402 . Changes in the total self-capacitance of common electrode  402  can be sensed through an operational amplifier, as previously discussed. The change in the total self-capacitance of common electrode  402  can depend on the proximity of a touch object, such as finger  305 , to the common electrode. In this way, the measured change in total self-capacitance of common electrode  402  can provide an indication of touch on or near the touch screen. 
     In general, each of the touch sensing circuit elements may be either a multi-function circuit element that can form part of the touch sensing circuitry and can perform one or more other functions, such as forming part of the display circuitry, or may be a single-function circuit element that can operate as touch sensing circuitry only. Similarly, each of the display circuit elements may be either a multi-function circuit element that can operate as display circuitry and perform one or more other functions, such as operating as touch sensing circuitry, or may be a single-function circuit element that can operate as display circuitry only. Therefore, in some examples, some of the circuit elements in the display pixel stackups can be multi-function circuit elements and other circuit elements may be single-function circuit elements. In other examples, all of the circuit elements of the display pixel stackups may be single-function circuit elements. 
     In addition, although examples herein may describe the display circuitry as operating during a display phase, and describe the touch sensing circuitry as operating during a touch sensing phase, it should be understood that a display phase and a touch sensing phase may be operated at the same time, e.g., partially or completely overlap, or the display phase and touch sensing phase may operate at different times. Also, although examples herein describe certain circuit elements as being multi-function and other circuit elements as being single-function, it should be understood that the circuit elements are not limited to the particular functionality in other examples. In other words, a circuit element that is described in one example herein as a single-function circuit element may be configured as a multi-function circuit element in other examples, and vice versa. 
     The common electrodes  402  (i.e., touch pixels) and display pixels  401  of  FIG. 4  are shown as rectangular or square regions on touch screen  400 . However, it is understood that the common electrodes  402  and display pixels  401  are not limited to the shapes, orientations, and positions shown, but can include any suitable configurations according to examples of the disclosure. 
     As described above, the self-capacitance of each common electrode  402  (i.e., touch pixel) in touch screen  400  can be sensed to capture an image of touch across touch screen  400 . Although not shown in  FIG. 4 , in mutual capacitance examples, the drive lines can be stimulated by one or stimulation signals, and the sense lines can be sensed to capture the image of touch. To allow for the sensing of the self-capacitance of individual common electrodes  402  in self-capacitance examples, or the driving and sensing of drive and sense lines in mutual capacitance examples, it can be necessary to route one or more electrical connections between each of the common electrodes (or drive and sense lines) and the touch circuitry (e.g., drive and sense circuitry). 
     In some example touch screen designs, connectivity between elements in the active area (the display area) of the touch screen and other areas such as off-panel connection areas is provided in the border areas of the touch screen, where non-transparent, lower resistance materials such as copper can be used. However, as the size and resolution of touch screens increases, the width of the border area needed to route all of the traces needed to connect the elements in the active area can increase, leading to undesirably wide border areas that reduce the area available for the touch screen and therefore the optical aperture. 
       FIG. 5  illustrates an exemplary touch screen display  500  with connecting traces routed in the border area according to some examples of the disclosure. In the example of  FIG. 5 , active area  502  can represent the portion of the touch screen that is capable of displaying images and also receiving touch or proximity input. Within the active area  502 , elements  504  can be formed. Elements  504  can be drive lines, sense lines, ground guards, or other structures that may need to be routed to an area of the touch screen for off-panel connections or other purposes. In the example of  FIG. 5 , connecting traces  506  can be coupled to elements  504  and routed in border areas  508  to off-panel connection areas or other areas (not shown in  FIG. 5 ). However, as the resolution of touch screens increases and more elements are located in the active area  502 , the required number of connecting traces  506  can increase, which can require a wider border area  508 . Furthermore, as the size of touch screens increases, the length of the connecting traces  506  can increase, which can undesirably increase the resistance of those traces. To keep trace resistance low, the width of connecting traces  506  can be increased, but that can also result in a wider border area  502 . A wider border area can undesirably reduce the optical aperture of the touch screen display and provide an unaesthetic appearance. 
       FIG. 6  illustrates another exemplary touch screen display  600  with connecting traces routed in the active area according to some examples of the disclosure.  FIG. 6  can represent an integrated display and touch (a.k.a. in-cell touch) example, where touch sensing elements are integrated with display elements, and in some cases configurable multi-function elements are utilized, but it should be understood that the disclosure is not limited to an in-cell touch configuration. In the example of  FIG. 6 , connecting traces  606  can be coupled to elements  604  and routed in the active area  602  to off-panel connection areas or other areas (not shown in  FIG. 6 ). In the example of  FIG. 6 , the elements  604  can be drive lines formed from connected Vcom segments (e.g., common electrodes used for both touch and display operations), and connectivity can be provided at both ends of the drive lines, but it should be understood that in some examples, the elements  604  can be any conductive material that needs to be routed to areas outside of the active area  602 , and both ends need not be connected. By routing the connecting traces  606  in the active area, the width of border areas  608  can be reduced significantly, or in some examples, the border areas can be eliminated altogether. In some examples, the connecting traces  606  can be formed from non-transparent metals such as copper to keep line widths smaller and resistance lower, but such connecting traces can reduce the optical aperture and uniformity of the touch screen display and create other undesirable optical artifacts. In some examples, the connecting traces  606  can be formed from transparent materials such as Indium Tin Oxide (ITO) to minimize the reduction in optical aperture and uniformity. However, the resistance of the connecting traces  606  can increase unless their widths are increased, which can counteract, to some extent, the improved optical aperture and uniformity. 
       FIG. 7  illustrates a top view of an exemplary stackup  700  of superimposed layers of a pixel layout according to some examples of the disclosure.  FIG. 7  illustrates an integrated display and touch (a.k.a. in-cell touch) example, where touch sensing elements are integrated with display elements, and in some cases configurable multi-function elements are utilized, but it should be understood that the disclosure is not limited to an in-cell configuration. In the example of  FIG. 7 , data lines  702  can be routed in the active area of the touch screen, and connecting traces  704  can be routed under the data lines  702 . In this way, the addition of connecting traces  704  within the active area should not affect the optical aperture and uniformity of the touch screen. Gate lines  706  can be routed under the connecting traces  704 . Although  FIG. 7  shows the connecting traces  704  routed under data lines  702 , in some examples the connecting traces can be routed under or over other opaque structures in the stackup. In some examples, connecting traces  704  can be formed of opaque metal such as copper, but in some examples, the connecting traces can be formed from transparent material such as ITO. In some examples where touch sensing circuitry is not integrated with display circuitry, the connecting traces  704  can be routed over opaque areas of the display circuitry, such as between sub-pixels, so as to not affect the optical aperture and uniformity of the touch screen. 
       FIG. 8  illustrates a top view of an exemplary connection architecture  800  according to some examples of the disclosure.  FIG. 8  illustrates an integrated display and touch example, but it should be understood that the disclosure is not limited to an integrated display and touch configuration. In the example of  FIG. 8 , a portion of the active area  802  is shown, and a portion of the border area  804  is shown. Active area  802  and border area  804  can be formed from multiple integrated Vcom layer portions  806 , which can also form display pixels when configured as a display. The integrated Vcom layer portions  806  can be combined to form drive line  808 , drive line  810 , drive line  812 , and border area  804 , though it should be understood that in some examples of the disclosure, areas  808 ,  810  and  812  can generally represent any conductive elements within the active area. (Note that although the electrical connections between integrated Vcom layer portions  806  using bridges, for example, are not shown for purposes of simplifying the figure, it should be understood that like-shaded Vcom layer portions are electrically connected.) 
     In order to produce touch data that is as unaffected by layout considerations as possible, it can be advantageous to form connecting traces whose resistances are substantially similar, so that the resistive loads seen by connected circuitry can be substantially the same. However, trace resistances can vary based on trace widths and lengths. In the example of  FIG. 8 , drive line portion  808  can be routed to off-panel connection areas, touch detection circuitry or other areas or circuits (not shown) using a single connecting trace  814 , which can be coupled to drive line portion  808  using contact  816 . Because connecting trace  814  is relatively short, its resistance can be relatively low. Drive line portion  810  can be routed using two connecting traces  818  which can be coupled to drive line portion  810  using two contacts. Because connecting traces  818  are longer than connecting trace  814 , if traces  814  and  818  have the same width, their individual resistances can be higher than that of single connecting trace  814 . However, because there are two connecting traces  818 , the two connecting traces effectively halve the total resistance of the connection, making the total resistance of the two connecting traces more closely match that of single connecting trace  814 . Similarly, the three connecting traces  820  for drive line  812  can make the total effective resistance of the connection more closely match that of connecting trace  814 . 
     It should be understood that the number of connecting traces for each drive line shown in  FIG. 8  is merely exemplary, and that other numbers of traces could be used in an attempt to equalize resistances. In addition, the connecting traces for a particular drive line need not be adjacent to each other. Furthermore, in some examples of the disclosure, the lengths of individual connecting traces can vary in an attempt to equalize resistances. For example, connecting trace  814  can make contact with drive line  808  at the lowest integrated Vcom layer portion (i.e., the fourth one down, instead of the second one down) to create additional length. In some examples of the disclosure, the widths of the individual connecting traces can vary in an attempt to equalize resistances. Any of these variations can be employed individually or in combination in an attempt to equalize the resistances between the drive lines and the off-panel connection areas, touch detection circuitry or other areas or circuits. 
     In addition, in order to produce touch data and/or display images that are as unaffected by layout considerations as possible, it can be advantageous to form connecting traces whose capacitances are substantially similar, so that the capacitive loads or coupling seen by connected or nearby circuitry can be substantially the same. However, trace capacitances can vary based on trace widths and lengths. Thus, in the example of  FIG. 8 , the connecting traces can extend beyond their contact point so that each connecting trace has approximately the same length. These extensions or dummy traces are shown at  822 . The bottom ends of these extensions can be left unconnected, so that little or no current flows in the extensions and the resistances of the connecting traces can be substantially unchanged. However, because the total lengths of these connecting traces are approximately equal, their capacitances can be approximately equal. Furthermore, in some examples of the disclosure, the lengths of individual connecting traces can vary in an attempt to equalize capacitances. For example, individual extensions  822  can extend beyond their contact points by varying amounts, to create varying lengths. In some examples of the disclosure, the widths of the individual connecting traces can vary in an attempt to equalize capacitances. Any of these variations can be employed individually or in combination in an attempt to equalize the capacitances of the connecting traces between the drive lines and the off-panel connection areas, touch detection circuitry or other areas or circuits. 
     By making the resistive and capacitive loads approximately equal, connected circuits can experience the same resistive-capacitive loading, and the effects of the resulting RC time constant on the signals being driven by, or received by, the connected circuits can be approximately equalized. In addition, by routing the connecting traces over most or all of the Vcom layer portions  806  and the stackups formed therefrom (e.g., over most or all of the display pixel stackups), even if the connecting traces do not make direct electrical contact with the stackups, each stackup can be fabricated similarly, and experience the same artifacts. For example, because each display pixel stackup can have a connecting trace routed within, each display pixel can experience similar parasitic capacitive coupling resulting from the connecting trace. 
       FIG. 9  illustrates an exemplary cross-section of an active area  900  of a touch screen according to some examples of the disclosure.  FIG. 9  illustrates an integrated display and touch example, but it should be understood that the disclosure is not limited to an integrated display and touch configuration. Note also that  FIG. 9  is intended to show representative structures, and not an actual cross-section of a working example. In the example of  FIG. 9 , the Vcom layer  902  can be formed from a “Metal 3” (M3) layer, data lines  904  can be formed from a “Metal 2” (M2) layer, and gate lines  906  can be formed from a “Metal 1” (M1) layer. Connecting traces  908  can be formed from a “Metal 2s” (M2s) layer. Insulating layer  910  can be formed to support the connecting traces  908 . M3 via  912  is shown as an example of a connection that can be made between the Vcom and data layer, and M2 via  914  is shown as an example of a connection that can be made between the data layer and the connecting trace layer. 
     Therefore, according to the above, some examples of the disclosure are directed to a touch screen comprising: a plurality of elements formed in a display area of the touch screen; and a plurality of connecting traces coupled to the plurality of elements and routed in the display area; wherein the plurality of connecting traces are configured to substantially balance a load created by the connecting traces, and substantially not affect an aperture ratio of the touch screen. Additionally or alternatively to one or more of the examples disclosed above, in some examples, one or more first connecting traces coupled to a first element are configured such that a total resistance of the one or more first connecting traces substantially matches a total resistance of one or more second connecting traces coupled to a second element. Additionally or alternatively to one or more of the examples disclosed above, in some examples, a length of the one or more first connecting traces is selected such that the total resistance of the one or more first connecting traces substantially matches the total resistance of the one or more second connecting traces. Additionally or alternatively to one or more of the examples disclosed above, in some examples, a width of the one or more first connecting traces is selected such that the total resistance of the one or more first connecting traces substantially matches the total resistance of the one or more second connecting traces. Additionally or alternatively to one or more of the examples disclosed above, in some examples, one or more first connecting traces coupled to a first element are configured such that a total capacitance of the one or more first connecting traces substantially matches a total capacitance of one or more second connecting traces coupled to a second element. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the touch screen further comprises a trace extension coupled to each of the one or more first connecting traces, the trace extensions configured such that the total capacitance of the one or more first connecting traces substantially matches the total capacitance of the one or more second connecting traces. Additionally or alternatively to one or more of the examples disclosed above, in some examples, a length of the trace extensions is selected such that the total capacitance of the one or more first connecting traces substantially matches the total capacitance of the one or more second connecting traces. Additionally or alternatively to one or more of the examples disclosed above, in some examples, a width of the trace extensions is selected such that the total capacitance of the one or more first connecting traces substantially matches the total capacitance of the one or more second connecting traces. Additionally or alternatively to one or more of the examples disclosed above, in some examples, each of the plurality of elements are formed from a plurality of display pixel stackups; and wherein the plurality of connecting traces are configured to equalize an effect of the connecting traces on the plurality of display pixel stackups. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the touch screen further comprises: a data layer; a gate layer; and a connecting trace layer formed between the data layer and the gate layer; wherein the plurality of connecting traces are formed in the connecting trace layer. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the plurality of connecting traces are configured to maximize an aperture ratio of the touch screen. Additionally or alternatively to one or more of the examples disclosed above, in some examples, at least one of the plurality of connecting traces is routed under an opaque area of the display area. Additionally or alternatively to one or more of the examples disclosed above, in some examples, at least one of the plurality of connecting traces is routed under a data line in the data layer. 
     Some examples of the disclosure are directed to a method of forming a touch screen comprising: routing a plurality of elements formed in a display area of the touch screen to a second area using a plurality of connecting traces routed in the display area; and forming the plurality of connecting traces to substantially balance a load created by the connecting traces, and substantially not affect an aperture ratio of the touch screen. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the method further comprises matching a total resistance of one or more first connecting traces coupled to a first element with a total resistance of one or more second connecting traces coupled to a second element. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the method further comprises selecting a length of the one or more first connecting traces such that the total resistance of the one or more first connecting traces substantially matches the total resistance of the one or more second connecting traces. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the method further comprises selecting a width of the one or more first connecting traces such that the total resistance of the one or more first connecting traces substantially matches the total resistance of the one or more second connecting traces. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the method further comprises matching a total capacitance of one or more first connecting traces coupled to a first element with a total capacitance of one or more second connecting traces coupled to a second element. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the method further comprises extending each of the one or more first connecting traces such that the total capacitance of the one or more first connecting traces substantially matches the total capacitance of the one or more second connecting traces. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the method further comprises selecting a length of the trace extensions such that the total capacitance of the one or more first connecting traces substantially matches the total capacitance of the one or more second connecting traces. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the method further comprises selecting a width of the trace extensions such that the total capacitance of the one or more first connecting traces substantially matches the total capacitance of the one or more second connecting traces. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the method further comprises: forming each of the plurality of elements from a plurality of display pixel stackups; and forming the connecting traces to equalize an effect of the connecting traces on the plurality of display pixel stackups. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the method further comprises forming the plurality of connecting traces between a data layer and a gate layer. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the method further comprises forming the plurality of connecting traces to maximize an aperture ratio of the touch screen. Additionally or alternatively to one or more of the examples disclosed above, in some examples, the method further comprises routing at least one of the plurality of connecting traces under an opaque area of the display area. 
     Although examples of this disclosure have been fully described with reference to the accompanying drawings, it is to be noted that various changes and modifications will become apparent to those skilled in the art. Such changes and modifications are to be understood as being included within the scope of examples of this disclosure as defined by the appended claims.

Metadata:
Filing Date: 20140923
Publication Date: 20201201
Grant Date: 20201201
Priority Date: 20140528
Inventors: JAMSHIDI-ROUDBARI, ABBAS
YU, CHENG-HO
CHANG, SHIH-CHANG
CHANG, TING-KUO
Assignee: APPLE INC
CPC Classifications: [{"code": "G06F3/04166", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0443", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/0416", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0445", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/0412", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F3/04166", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F2203/04108", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/04164", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/044", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F2203/04104", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/0412", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F3/0443", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/04164", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0445", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F2203/04108", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/0416", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F3/0412", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F2203/04104", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/044", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 54699480