PATENT DOCUMENT

Publication Number: US-8816967-B2
Application Number: US-23768708-A
Country: US
Kind Code: B2

Title: Capacitive sensor having electrodes arranged on the substrate and the flex circuit

Abstract:
A capacitive sensor may include a flex circuit, a substrate facing the flex circuit, and conductive electrodes configured to sense an input applied to the substrate. At least one of the conductive electrodes is associated with a surface of the substrate and an at least one of the electrodes is associated with a surface of the flex circuit.

Claims:
What is claimed is: 
     
       1. A capacitive sensor comprising:
 a flex circuit, 
 a substrate, and 
 a plurality of conductive electrodes configured to sense an input associated with the substrate, the plurality of conductive electrodes comprising at least one electrode associated with a surface of the substrate and at least one electrode associated with a surface of the flex circuit, 
 a notch defined in the flex circuit, the notch establishing a physical gap in the flex circuit and a discontinuity in the at least one electrode associated with a surface of the flex circuit, 
 the at least one electrode associated with a surface of the substrate being configured so that the at least one electrode associated with a surface of the substrate fills at least a portion of the physical gap in the flex circuit and is continuous with and electrically coupled to the at least one electrode associated with a surface of the flex circuit when the substrate and the flex circuit are in a facing relationship. 
 
     
     
       2. The capacitive sensor of  claim 1 , wherein the substrate comprises at least one of a glass, plastic, ceramics, or polyethylene terephthalate (PET) material. 
     
     
       3. The capacitive sensor of  claim 2 , wherein the electrode associated with the surface of the substrate is formed via at least one of painting, printing or sputtering. 
     
     
       4. The capacitive sensor of  claim 3 , wherein a sensing area of the flex circuit is smaller than a total area of the substrate. 
     
     
       5. The capacitive sensor of  claim 1 , wherein the substrate comprises material having a sheet resistance less than 100 ohms/square area. 
     
     
       6. The capacitive sensor of  claim 1 , wherein the plurality of conductive electrodes comprises:
 a first plurality of electrodes associated with the flex circuit in a first linear arrangement, the first plurality of electrodes being electrically coupled to each other, and 
 a second plurality of electrodes associated with the flex circuit in a second linear arrangement substantially perpendicular to the first linear arrangement, the second plurality of electrodes being electrically coupled to each other. 
 
     
     
       7. The capacitive sensor of  claim 6 , wherein the first plurality of electrodes are electrically coupled on the surface of the flex circuit and the second plurality of electrodes are electrically coupled on an opposite surface of the flex circuit using vias through which the second plurality of electrodes are connected to corresponding electrical patterns associated with the opposite surface of the flex circuit. 
     
     
       8. The capacitive sensor of  claim 6 , wherein the first plurality of electrodes are electrically coupled to each other on the surface of the flex circuit and the second plurality of electrodes are electrically coupled to each other, overlapping areas between adjacent ones of the second plurality of electrodes on the substrate, via a plurality of conductive patterns associated with the substrate. 
     
     
       9. The capacitive sensor of  claim 6 , wherein the electrode associated with the surface of the substrate comprises conductive material overlapping a portion of at least one of the first plurality of electrodes to electrically connect to the first plurality of electrodes. 
     
     
       10. The capacitive sensor of  claim 6 , wherein at least one of the first plurality of electrodes forms a mutual capacitance with at least one surrounding electrode of the second plurality of electrodes, an application of the input to the substrate causing a change in an electric charge of the at least one surrounding electrode indicative of the location of the application of the input. 
     
     
       11. The capacitive sensor of  claim 6 , wherein the plurality of conductive electrodes operate based on self-capacitance and both the first and second plurality of electrodes are sensed, an application of the input to the substrate creating a capacitance with at least one of the first plurality of electrodes and at least one of the plurality of second electrodes indicative of the location of the application of the input. 
     
     
       12. The capacitive sensor of  claim 1 , comprising a plurality of traces, at least one of the traces being coupled individually to one of the plurality of conductive electrodes. 
     
     
       13. The capacitive sensor of  claim 12 , wherein the plurality of conductive electrodes are arranged in a circular pattern. 
     
     
       14. A capacitive sensor comprising:
 a flex circuit, 
 a substrate, and 
 a plurality of conductive electrodes configured to sense an input associated with the substrate, the plurality of conductive electrodes comprising a first plurality of electrodes having a first linear arrangement on a surface of the flex circuit and a second plurality of electrodes having a second linear arrangement on a surface of the substrate, an application of the input to the substrate causing a change in an electric charge of at least one electrode indicative of the location of an application of the input, 
 a notch defined in the flex circuit, the notch establishing a physical gap in the flex circuit and a discontinuity in at least one electrode associated with a surface of the flex circuit, 
 at least one electrode associated with a surface of the substrate being configured so that the at least one electrode associated with a surface of the substrate is continuous with and electrically coupled to the at least one electrode associated with a surface of the flex circuit and fills at least a portion of the physical gap in the flex circuit when the substrate and the flex circuit are in a facing relationship. 
 
     
     
       15. A capacitive sensor of  claim 14 , comprising an insulating layer arranged between the first and second plurality of electrodes. 
     
     
       16. The capacitive sensor of  claim 14 , wherein the substrate comprises at least one of a glass, plastic, ceramics, or polyethylene terephthalate (PET) material and the second plurality of electrodes are formed via at least one of painting, printing or sputtering. 
     
     
       17. A capacitive sensor comprising:
 a flex circuit, 
 a substrate, 
 multiple conductive electrodes formed on and defining an electrode pattern on the flex circuit and configured to sense an input associated with the substrate, the multiple conductive electrodes comprising first electrodes and second electrodes, the first and second electrodes being mutually perpendicular and having an insulating layer therebetween, and 
 at least one electrode associated with a surface of the substrate and electrically connected to the first electrodes, wherein the substrate faces the flex circuit and the electrode associated with the substrate overlaps an area of the flex circuit that comprises a notch, wherein the notch prohibits placement of a portion of at least one of the first electrodes in a continuous pattern, the electrode associated with the substrate being configured to duplicate at least a portion of the electrode pattern on the flex circuit when the substrate and the flex circuit are in a facing relationship. 
 
     
     
       18. The capacitive sensor of  claim 17 , wherein the notch also displaces a pattern of the second plurality of electrodes, the capacitive sensor comprising:
 at least one electrode associated with the surface of the substrate and coupled to the second plurality of electrodes, and 
 a layer of insulating material formed between the at least one electrode associated with the surface of the substrate and coupled to the first plurality of electrodes and the at least one electrode associated with the surface of the substrate and coupled to the second plurality of electrodes. 
 
     
     
       19. The capacitive sensor of  claim 17 , wherein the substrate comprises at least one of a glass, plastic, ceramics, or polyethylene terephthalate (PET) material, and the first electrode is formed on the surface of the substrate via at least one of painting, printing or sputtering. 
     
     
       20. A media player comprising a capacitive sensor, the capacitive sensor comprising:
 a flex circuit, 
 a substrate, and 
 a plurality of conductive electrodes configured to sense an input associated with the substrate, the plurality of conductive electrodes comprising at least one electrode associated with a surface of the substrate and at least one electrode associated with a surface of the flex circuit, 
 a notch defined in the flex circuit, the notch establishing a physical gap in the flex circuit and a discontinuity in the at least one electrode associated with a surface of the flex circuit, 
 the at least one electrode associated with a surface of the substrate being configured to fill at least a portion of the physical gap in the flex circuit so that the at least one electrode associated with a surface of the substrate is continuous with and electrically coupled to the at least one electrode associated with a surface of the flex circuit when the substrate and the flex circuit are in a facing relationship. 
 
     
     
       21. A method of manufacturing a capacitive sensor, comprising:
 forming at least one electrode associated with a surface of a substrate, 
 forming at least one electrode associated with a surface of a flex circuit, and 
 arranging the substrate and the flex circuit such that the electrode associated with the surface of the substrate and the electrode associated with the surface of the flex circuit are positioned between the substrate and the flex circuit, 
 a notch defined in the flex circuit, the notch establishing a physical gap in the flex circuit and a discontinuity in the at least one electrode associated with a surface of the flex circuit, 
 the at least one electrode associated with a surface of the substrate being configured to fill at least a portion of the physical gap in the flex circuit so that the at least one electrode associated with a surface of the substrate is continuous with and electrically coupled to the at least one electrode associated with a surface of the flex circuit when the substrate and the flex circuit are in a facing relationship. 
 
     
     
       22. The method of  claim 21 , comprising forming an insulating layer between the electrode associated with the surface of the substrate and the electrode associated with the surface of the flex circuit. 
     
     
       23. The method of  claim 21 , wherein the substrate comprises at least one of a glass, plastic, ceramics, or polyethylene terephthalate (PET) material and the step of forming the electrode associated with the surface of the substrate comprising at least one of painting, printing or sputtering a conductive material on the substrate. 
     
     
       24. The method of  claim 21 , wherein a sensing area of the flex circuit is smaller than the area of the substrate, the step of forming the electrode associated with the surface of the substrate comprising:
 identifying an area of the substrate overlapping a notch of the flex circuit, and 
 forming the electrode associated with the surface of the substrate within the identified area. 
 
     
     
       25. The method of  claim 21 , further comprising:
 forming a first plurality of electrodes on the flex circuit in a first linear arrangement, the first plurality of row electrodes being electrically coupled to each other, and 
 forming a second plurality of electrodes on the flex circuit in a second linear arrangement substantially perpendicular to the first linear arrangement, the second plurality of electrodes being electrically coupled to each other. 
 
     
     
       26. The method of  claim 25 , wherein the electrode associated with the surface of the substrate comprises conductive material overlapping a portion of at least one of the first plurality of electrodes to electrically connect to the first plurality of electrodes. 
     
     
       27. The method of  claim 25 , wherein at least one of the first plurality of electrodes forms a mutual capacitance with at least one adjacent electrode of the second plurality of electrodes, an application of an input to the substrate causing a change in an electric charge of the at least one adjacent electrode indicative of the location of the application of the input. 
     
     
       28. The method of  claim 25 , wherein the plurality of conductive electrodes operate based on self-capacitance, an application of an input to the substrate causing a change in electric charges of at least one of the first plurality of electrode and at least one of the plurality of second electrodes indicative of the location of the application of the input. 
     
     
       29. A capacitive sensor comprising:
 a flex circuit comprising a surface, 
 a substrate comprising a surface, 
 multiple conductive electrodes configured to sense input, the multiple conductive electrodes comprising at least a first electrode and a second electrode, the first electrode being associated with the substrate surface and the second electrode defining an electrode pattern and being associated with the flex circuit surface, 
 a notch defined in the flex circuit, the notch establishing a discontinuity in the second electrode, 
 the first electrode being configured to duplicate at least a portion of the electrode pattern of the second electrode and electrically couple to the second electrode and eliminate the discontinuity when the substrate and the flex circuit are in a facing relationship. 
 
     
     
       30. A capacitive sensor comprising:
 a flex circuit having a surface, 
 a substrate having a surface, 
 a first plurality of electrodes associated with the surface of the flex circuit, 
 a second plurality of electrodes defining an electrode pattern and being associated with the surface of the substrate, 
 at least one electrode associated with the surface of the substrate and at least one electrode associated with the surface of the flex circuit being electrically coupled when the substrate and the flex circuit are in a facing relationship, wherein both the first and second plurality of electrodes are configured to sense input associated with the substrate, the first plurality of electrodes being configured to duplicate at least a portion of the electrode pattern of the second plurality of electrodes when the substrate and the flex circuit are in a facing relationship. 
 
     
     
       31. The capacitive sensor of  claim 30 , wherein the substrate comprises at least one of glass, plastic, ceramics or polyethylene terephthalate (PET). 
     
     
       32. The capacitive sensor of  claim 31 , wherein the second plurality of electrodes are formed by at least one of painting, printing or sputtering. 
     
     
       33. The capacitive sensor of  claim 30 , wherein the substrate is characterized by a sheet resistance of less than 100 ohms/square area. 
     
     
       34. The capacitive sensor of  claim 30 , wherein
 the first plurality of electrodes are electrically coupled to one another, 
 the second plurality of electrodes are electrically coupled to one another, and 
 the first plurality of electrodes and the second plurality of electrodes are mutually perpendicular when the substrate and the flex circuit are in a facing relationship. 
 
     
     
       35. The capacitive sensor of  claim 30 , comprising an insulating layer between the first and second plurality of electrodes. 
     
     
       36. A method of manufacturing a capacitive sensor, comprising:
 forming a first plurality of electrodes on a surface of a flex circuit, 
 forming a second plurality of electrodes defining an electrode pattern on a surface of a substrate, 
 arranging the substrate and the flex circuit in a facing relationship wherein the first and second plurality of electrodes are positioned between the substrate and the flex circuit, 
 electrically coupling at least one of the first plurality of electrodes and at least one of the second plurality of electrodes, 
 wherein both the first and second plurality of electrodes are configured to sense input associated with the substrate, and wherein the first plurality of electrodes is configured to duplicate at least a portion of the electrode pattern of the second plurality of electrodes when the substrate and the flex circuit are in a facing relationship. 
 
     
     
       37. A capacitive sensor comprising:
 a flex circuit comprising a surface, 
 a substrate comprising a surface, 
 multiple conductive electrodes, the multiple conductive electrodes comprising at least a first electrode and a second electrode, the first electrode being associated with the substrate surface and the second electrode defining an electrode pattern and being associated with the flex circuit surface, 
 the first and second electrodes being configured to be electrically coupled when the substrate and the flex circuit are in a facing relationship, wherein both the first and second plurality of electrodes are configured to sense input associated with the substrate, the first electrode being configured to duplicate at least a portion of the electrode pattern of the second electrode when the substrate and the flex circuit are in a facing relationship.

Description:
BACKGROUND 
     1. Field 
     This disclosure relates to input devices, and more particularly to a capacitive sensor of an input device. 
     2. Description of the Related Art 
     Several kinds of input devices exist for performing operations in a computing device. Some examples of input devices include buttons, switches, keyboards, mice, trackballs, touch pads, joy sticks, touch screens and the like. Some examples of computing devices include personal computers, media players, remote controls, personal digital assistants (PDAs), cellular phones, etc. Operations performed by the input devices generally may include, for example, moving a cursor to select items displayed on a display screen of the computing devices or browsing through a list of audio files to select an audio file for play. 
     As computing devices evolve, they tend to decrease in size while providing increased features. In light of this, designing input devices for these computing devices can present unique issues. 
     For example, a touch screen input device that includes an array of capacitive electrodes arranged within a conductive range with an object touching the screen. As the size of the portable computing device decreasing, the space available for the placement of the electrodes typically decreases. For example, as the circuit components are packed more tightly together, it is often needed to utilize all space available on a circuit board. Thus, the conventional placement of the electrodes within a single layer may be problematic where an area of the layer needs to be used for other device modules, e.g., a video processor or sound card, or where the layer physically interferes with other components of the device such as, for example, an input receptacle. Accordingly, the design of input devices for such devices can be constrained by efforts to conserve a limited amount of space. 
     SUMMARY 
     This disclosure relates, in one embodiment, to a capacitive sensor. The capacitive sensor may include a flex circuit and a substrate. The substrate may be facing the surface of the flex circuit and made of glass material, plastic material, ceramics, or polyethylene terephthalate (PET) material, etc. In an exemplary embodiment, the substrate material has a sheet resistance less than 100 ohms/square area. The capacitive sensor also includes at least one electrode formed on the substrate and at least one electrode formed on the flex circuit. The former electrode may be painted, printed, or sputtered on the substrate. 
     In one embodiment, the flex circuit may include a notch. The notch may include an area that has been cut out of the flex circuit, is occupied by another circuit module, or is otherwise unavailable for placement of electrodes on the flex circuit. To construct a continuous arrangement of electrodes, an electrode is formed on the substrate overlapping the area of the notch to supplement the electrodes arranged on the flex circuit. 
     According to a further embodiment, the electrodes may be arranged as a first set of electrodes arranged in a first linear arrangement and a second set of electrodes arranged in a second linear arrangement. For example, the electrodes may be arranged in rows and columns. All the electrodes within each row may be electrically connected to each other and all the electrodes within each column may be electrically connected to each other. On an area of the substrate overlapping the notch of the flex circuit, at least one electrode may be arranged to line up with and electrically couple to one or more of the electrodes of the flex circuit. 
     According to an embodiment, the flex circuit may include an array of electrodes. Each electrode may be coupled individually to a trace arranged on the lower surface of the substrate such that an input applied to any single electrode can be identified. The flex circuit may include a notch. A set of electrodes may thus be formed on the substrate above the notch to supplement the electrode arrangement of the flex circuit in a continuous pattern. 
     According to yet another embodiment, the electrodes may be grouped into a first set of electrodes arranged in a first linear arrangement on the flex circuit and a second set of electrodes arranged in a second linear arrangement on the substrate. For example, the electrodes may be arranged as rows formed on a surface of the flex circuit and in columns formed on an opposite surface of the substrate, or vice versa. A layer of insulating material may also be formed between the rows and the columns. In this embodiment, the row electrodes and column electrodes form a mutual capacitance similar to the above-described embodiment. 
     In yet another embodiment, the rows and columns of electrodes may be both formed on the flex circuit. An area of the flex circuit includes a notch as described above. Thus, in this embodiment, corresponding rows and columns are formed on an area of the substrate overlapping the notch in a pattern that is continuous with and electrically coupled to the arrangement of the rows and columns on the flex circuit. The rows and columns may be painted, printed, or sputtered on the substrate and may include a layer of insulating material therebetween. 
     According to another aspect, there is provided a computer device including a capacitive sensor as described in the aforementioned embodiments, coupled to a sensing unit that senses the location of a an input applied to the sensor. 
     According to yet another aspect, there is provided a method of manufacturing a capacitive sensor. The method may include, in one embodiment: forming at least one electrode associated with a substrate, forming at least one electrode associated with a flex circuit, and arranging the substrate and the flex circuit such that the electrodes are positioned between the substrate and the flex circuit. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The embodiments are illustrated by way of example, not by way of limitation, in the figures of the accompanying drawings as follows: 
         FIGS. 1   a - 1   b  depict exemplary perspective views of a flex circuit of a capacitive sensor having a double-diamond electrode pattern. 
         FIG. 2   a  depicts an exemplary perspective view of an surface of a flex circuit having a double-diamond electrode pattern including a notch. 
         FIG. 2   b  depicts an exemplary perspective view of a lower surface of a substrate arranged facing the flex circuit of  FIG. 2   a.    
         FIG. 2   c  depicts an exemplary perspective view of a lower surface of the flex circuit of  FIG. 2   a.    
         FIG. 3   a  depicts an exemplary perspective view of a surface of another exemplary flex circuit having a double-diamond electrode pattern including a notch. 
         FIG. 3   b  depicts an exemplary perspective view of a lower surface of a substrate arranged facing the flex circuit of  FIG. 3   a.    
         FIG. 3   c  depicts an exemplary perspective view of a lower surface of the flex circuit of  FIG. 3   a.    
         FIG. 3   d  depicts an exemplary perspective view of a lower surface of another exemplary substrate arranged facing the flex circuit of  FIG. 3   a.    
         FIG. 3   e  depicts an exemplary perspective view of a zoomed-in portion of  FIG. 3   d.    
         FIGS. 4   a - 4   c  depict exemplary cross-sectional views of a capacitive sensor including a flex circuit having a notch. 
         FIG. 5  depicts an exemplary perspective view of a lower surface of yet another exemplary substrate arranged facing the flex circuit of  FIG. 3   a.    
         FIG. 6  depicts an exemplary perspective view of a surface of yet another exemplary flex circuit of a capacitive sensor having a mutual-capacitance pattern. 
         FIG. 7   a  depicts an exemplary perspective view of a surface of a flex circuit having a mutual-capacitance pattern including a notch. 
         FIG. 7   b  depicts an exemplary perspective view of a lower surface of a substrate arranged facing the flex circuit of  FIG. 7   a.    
         FIG. 8  depicts an exemplary cross-sectional view of a capacitive sensor having rows and columns of a mutual-capacitance pattern arranged on the flex circuit and the substrate, respectively. 
         FIGS. 9   a - 9   b  depicts an exemplary perspective view of a surface of flex circuit of a capacitive sensor having a circular electrode pattern. 
         FIG. 10   a  depicts an exemplary perspective view of a surface of a flex circuit having a circular electrode pattern including a notch. 
         FIG. 10   b  depicts an exemplary perspective view of a lower surface of a substrate arranged facing the flex circuit of  FIG. 10   a.    
         FIG. 11  illustrates an simplified exemplary block diagram of a computing system, according to one aspect. 
         FIG. 12  depicts an exemplary flow process diagram for manufacturing a capacitive sensor, according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Various embodiments are discussed below with reference to  FIGS. 1   a - 12 . However, those skilled in the art will readily appreciate that the detailed description given herein with respect to these figures is for explanatory purposes as the subject matter extends beyond these limited embodiments. 
       FIG. 1   a  depicts a perspective diagram of a flex circuit  100  of a capacitive sensor, according to an exemplary embodiment. The flex circuit  100  is a type of flexible circuit or flexible circuit board, such as a flexible high-performance plastic substrate, used for mounting electronic devices. Examples of a flex circuit  100  include a polyimide and polyetheretherketone (PEEK) film. The flex circuit  100  may be manufactured using identical components used for rigid printed circuit boards, allowing the board to conform to a desired shape, or to flex during its use. 
     The flex circuit  100  may include several rows  102  of row electrodes  112  and several columns  104  of column electrodes  114  arranged on a first surface of the flex circuit  100 . The conductive electrodes  112 ,  114  may be arranged in a double-diamond pattern in which all row electrodes  112  are electrically connected within each row  102  and all column electrodes  114  are electrically connected within each column  104 . 
     Two adjacent row electrodes  112  may be connected via an area  116  located between two intermediary column electrodes  114  in the vertical direction. The area  116  separates the two column electrodes  114 , but includes conductive material to electrically connect the row electrodes  112 . In an exemplary embodiment, the area  116  may be very small, e.g., 0.1 mm wide. The area  116  may be constructed such that it electrically isolates the column electrodes  114  in the vertical direction while electrically connecting the row electrodes  112 . The column electrodes  114 , which are separated by the areas  116 , may be electrically connected via electrical patterns  120  arranged on a second surface of the flex circuit  100 , as shown in  FIG. 1   b . The electrical patterns are coupled to the column electrodes via vias  118  through the flex circuit  100 . 
     In addition to the flex circuit  100 , the capacitive sensor may also include a substrate arranged facing the flex circuit  100 . A first surface of the substrate constitutes the sensing surface of the capacitive sensor. This substrate may be made of different material such as, for example, glass, plastic, Polyethylene terephthalate (PET), ceramics, or other material. In an exemplary embodiment, the substrate material has a sheet resistance less than 100 ohms/square area. The substrate may be thin enough to allow objects, such as human fingertips, touching or coming in close proximity to its first surface to form a capacitance with the electrodes  112 ,  114 . 
     The capacitive sensor may operate based on self capacitance, according to one embodiment. In self capacitance, the “self” capacitance of a single electrode is measured as, for example, relative to ground. In an exemplary embodiment, an input applied to the substrate, such as a finger touching or coming in close proximity of the surface of the substrate, may form the second plate of a two-plate capacitor. The finger effectively capacitively couples to the lower electrode, thus changing the capacitance of the electrode beneath the finger by some small amount. In some cases, the change in capacitance may be on the order of 1-2%. A controller or processor may continuously measure the capacitance of each electrode in the grid. When the controller or processor detects an increased capacitance in the electrode at a certain spot of the grid, the position of the finger is located. In an exemplary embodiment, each row and column of the electrodes may be continuously monitored to measure capacitances. A detailed description of self capacitance is provided in U.S. Application Publication No. 2006/0290677, which is incorporated herein by reference in its entirety. 
     According to an alternative embodiment, the capacitive sensor may operate based on mutual capacitance. In mutual capacitance, the mutual capacitance between at least two electrodes is measured. In an exemplary embodiment, each row electrode forms a mutual capacitance with its adjacent column electrodes. The rows are driven by a driving circuit periodically and the charges released from the row electrodes to the column electrodes are sensed on the column electrodes. When an input is applied to the surface, such as an finger touching or coming into close proximity of the surface, the application of the input to the surface takes away some of the charge that would have been released to the column electrode near the point of contact. Thus, by sensing the row being driven and the column carrying a smaller charge than expected, the position of touch of the fingertip can be determined. 
     The row electrodes  112  and the column electrodes  114  may be electrically isolated from each other by a separation  110  on the flex circuit  100 . The separation  110  may include dielectric material to provide greater capacitance between the electrodes  112 ,  114  where the electrodes operate based on mutual capacitance. Where self capacitance is used, the separation  110  may include insulating material having a relatively high dielectric constant to minimize shorts between the electrodes  112 ,  114 . Alternatively, the flex circuit  100  itself provides sufficient insulation between the respective electrodes. 
     According to an embodiment, when trying to reduce size of a computing device that includes the flex circuit  100  of  FIG. 1   a , the placement of all electrodes  112 ,  114  on the flex circuit  100  may interfere with other circuitry on the flex circuit  100 . For example, a portion of the area of the first surface of the flex circuit  100  may be occupied by a circuit module in a way that the electrodes  102 ,  104  can not be placed directly on that area of the flex circuit  100 . Also, in some circumstances, a portion of the flex circuit  100  may need to be utilized to make room for other device components. For example, in a compact multi-media device utilizing the flex circuit  100 , it may be needed to physically notch a portion of the flex circuit to make room for an input receptacle. In these situations, it is possible to introduce a new layer on the flex circuit fully dedicated to placement of electrodes  102 ,  104 . However, doing so would require increasing the height of the device, which may be undesirable for many such input devices. 
     Thus, according to an embodiment, in order to maximize the use of the first surface of the flex circuit without increasing the size of the device, one or more of the electrodes may be formed on the first surface of the flex circuit while the remaining electrodes are formed on the opposing surface of the substrate. When the flex circuit and the substrate are placed together during the manufacturing process, the electrodes arranged on the substrate and the flex circuit may be aligned together to achieve a desired pattern similar to the pattern shown in  FIG. 1   a.    
     Various different methods may be utilized to place the electrodes on the substrate. For example, the electrodes may be painted on the substrate using conductive paint or printed on the substrate using conductive ink. Alternatively, the conductive material may be sputtered on the substrate to obtain the electrodes. In some embodiments, insulating material may also be formed between the electrodes to create more efficient capacitance between the electrodes. Also, once the electrodes have been formed, an additional layer of insulating material may be formed on the electrodes to further insulate the electrodes from the underlying circuitry or other underlying modules, except for areas where the substrate electrodes need to have electrical contact with the underlying electrodes. 
       FIG. 2   a  illustrates an exemplary flex circuit  200  having a notch  202 . Although the notch  202  is shown as being cut out in this embodiment, a notch may also refer to a portion that is not physically cut out from the flex circuit, but is occupied by another circuit module or is otherwise unavailable for placement of electrodes on the flex circuit. For example, the notch  202  may include an area of the flex circuit  202  that is occupied by a circuit module. Further, although the depicted notch is rectangular and is located in the proximity of a border of the flex circuit, a notch may be of any shape and may be located anywhere on the flex circuit. In various embodiments, the notch may displace a portion of the pattern of sensing electrodes on the flex circuit. 
     To obtain a complete pattern of sensing electrodes, the electrodes displaced from the electrode pattern on the flex circuit are formed on the surface of the substrate  210  facing the flex circuit  200 , shown in  FIG. 2   b . The row electrodes  212  and column electrodes  214  correspond to missing portions of electrodes  208   a - 208   c  arranged on the flex circuit  200  at the border of the notch  202 , in addition to a lower triangular electrode that has no corresponding electrode on the flex circuit  200 . The area  216  of the substrate corresponds to the notch  202  of the flex circuit  200 . In one embodiment, after formation of the electrodes  212 ,  214 , the area  216  of the substrate may be covered with a layer of insulating material to prevent electrical shortage between the electrodes  212 ,  214  and whatever module placed inside the notch  202 . 
     To electrically connect the row electrodes  212  and column electrodes  214  to the rows  102  and columns  104  of the flex circuit  200 , respectively, the flex circuit  200  may be further provided with contacts  204  on the electrodes  208   a - 208   c  of the flex circuit  200 . Thus, when the substrate  210  is placed facing the flex circuit  200  during the manufacturing process, an electrical connection is made between the substrate electrodes  212 ,  214  and the electrodes  208   a - 208   c , respectively. Alternatively, the contacts  204  may be formed on the substrate  210  and later connected to the  208   a - 208   c . In yet another embodiment, the row electrodes  212  and column electrodes  214  may be constructed such that they cover the entire surface of the electrodes  208   a - 208   c  and make an electrical connection with the electrodes  208   a - 208   c  without a need for the contacts  204 . 
     In order to ensure that the lower column electrode  214  is electrically connected to the upper column electrode  214 , an area  218  is provided between the two row electrodes  212  in the horizontal direction. Conductive material is disposed on the area  216  so as to connect the column electrodes  214  while electrically insulating the row electrodes  212 . In order to electrically connect the row electrodes  212 , an electrical connectivity may be provided to both sides of the rows  102  on the flex circuit such that both electrodes  208   a ,  208   b  are electrically connected to the same row without a need to create a direct connection from the electrodes  208   a  to the electrode  208   b . Alternatively, as shown in  FIGS. 2   a  and  2   c , the electrodes  208   a ,  208   b  may be coupled together via an conductive pattern  220  arranged on the second surface of the flex substrate  200 , via two vias  206  that connect the electrodes  208   a ,  280   b  to the conductive pattern  220  through the flex circuit  200 . 
       FIG. 3   a  depicts an exemplary flex circuit  300  having a notch  302  that is relatively larger than the notch  202  shown in  FIG. 2   a . In this embodiment, the notch  302  may be large enough to displace several electrodes from the flex circuit  300 . In order to provide sensing capabilities on the area of the notch  302 , a pattern similar to the electrode pattern of  FIG. 2   b  may be provided on the substrate  310  and electrically coupled to the rows  102  and columns  104  of the flex circuit  300 . Similarly to the flex circuit  200  shown in  FIG. 2   a , the row electrodes and column electrodes arrange on the flex circuit  300  around the border of the notch  302  may be coupled to the corresponding row electrodes  312  and column electrodes  314  via contacts  304 . Thus, when the substrate  310  is placed on the flex circuit  300  during the manufacturing process, an electrical connection is made between the substrate electrodes  312 ,  314  located on the edge of the notch  302  and the electrodes located on the flex circuit  300  near the border of the notch  302 . Alternatively, the contacts  304  may be formed on the substrate  310  and later connected to the electrodes of the flex circuit  300  located near the border of the notch  302 . In yet another embodiment, the row electrodes  312  and column electrodes  314  may be provided such that they cover the entire surface of the electrodes on the border of the notch  302  and make an electrical connection therewith after the substrate  310  is securely placed facing the flex circuit  300 , without a need for the contacts  304 . 
     The area  316  shown in  FIG. 3   b  corresponds to the notch  302  of the flex circuit  300 . As previously explained, the area  316  may be covered with a layer of insulating material to prevent shortage of the electrodes  312 ,  314 . The column electrodes  314  are electrically connected in a vertical direction on the surface of the substrate  310  via areas  318  which separate the row electrodes  312 . In one embodiment, the outer row electrodes  312  may be connected using vias  306  and electrical patterns  320 ,  322  formed on the second surface of the flex circuit  300 , as shown in  FIG. 3   c . Alternatively, electrical connectivity may be provided on both sides of the rows  102  such that the row electrodes on the border of the notch  302  may be electrically connected without a need to connect them through the second surface of the flex circuit  300 . In both these embodiments, however, the row electrodes  312   a ,  312   b  positioned in an intermediary portion of the area  316  may remain disconnected from the other row electrodes  102 . Thus, in these embodiments, a controller or processor coupled to the rows  102  and columns  104  may be configured such that when one or more of the columns  104  connected to the column electrodes  314  indicates an input being applied, while none of the rows  102  indicate an input being applied, it may be determined that the input is applied to an area of or near the row electrodes  312   a ,  312   b.    
     Alternatively, the row electrodes  312   a ,  312   b  may be connected to their adjacent row electrodes  312  on the substrate.  FIG. 3   d  depicts the substrate  310  in accordance to this embodiment, in which the row electrodes  312   a ,  312   b  are connected to their adjacent row electrodes  312  in the horizontal direction via an additional conductive layer  324  formed on the area  318 . The conductive layer  324  may be insulated from the area  318  via a layer of insulating material. 
       FIG. 3   e  depicts a magnified view  330  of the substrate  310 , including the conductive layer  324  and the layer of insulating material  332 . Both the insulating material  332  and the conductive layer  324  may be painted, printed, or sputtered on the substrate  310  after the electrodes  312 ,  314  have been formed. The thickness of the paint or ink may be so small such that it creates negligible interference with any module located within the notch  302  of the flex circuit  300 . To further insulate the electrodes  312 ,  314  as well as the aforementioned layers  324 ,  332 , an additional insulating layer (not shown) may also be formed at the end of the manufacturing process to prevent exposure of any conductive layer formed on the substrate  310 . 
       FIGS. 4   a - 4   c  provide a cross-sectional views of the substrate  310  and the flex circuit  300  near an area of the notch  302 , according to an exemplary embodiment.  FIG. 4   a  represents the view points  402 ,  404  shown in  FIGS. 4   b  and  4   c , respectively. 
       FIG. 4   b  represents a vertical cross-sectional view  402  of the substrate  310  and the flex circuit  300  near an area of the notch  302 , according to an exemplary embodiment. In this figure, the cross-sectional view is from a left side of the flex circuit  300  shown in  FIG. 4   a . As shown in this embodiment, the column electrodes  114  arranged on the flex circuit  300  are separated by an area  116 . The column electrodes are electrically connected to each other via two vias  306  coupled to electrical pattern  120  on an opposite surface of the flex circuit  300 . On an area bordering the notch  302 , the column electrode  114  makes an electrical contact with a column electrode  314  formed on the substrate  310 . In an embodiment, the column electrode  114  may not make a direct contact with the column electrode  314 , but may rather be separated from the column electrode  314  via an insulating layer and may be electrically connected to the column electrode  314  via a contact  304  (not shown) through the insulating layer. The column electrodes  314  thus supplement the pattern of the column electrodes  114  in a continuous fashion. The column electrodes  314  are connected via areas  318  located between the row electrodes  312  (not shown). The row electrodes  312  (not shown) are connected to each other via conductive layers  324  formed on an insulating layer  332 . 
       FIG. 4   c  represents a horizontal cross-sectional view  404  of the substrate  310  and the flex circuit  300  near an area of the notch  302 , according to an exemplary embodiment. In this figure, the cross-sectional view is from a lower side of the flex circuit  300  shown in  FIG. 4   a . As shown in this embodiment, the row electrodes  112  are connected to each other on the flex circuit  300  through the area  116 . Near the border of the notch  302 , the row electrode  112  makes an electrical contact with a row electrode  312  formed on the substrate  310 . In an embodiment, the row electrode  112  may not make a direct contact with the row electrode  312 , but may rather be separated from the row electrode  312  via an insulating layer and may be electrically connected to the row electrode  312  via a contact  304  (not shown) through the insulating layer. The row electrodes  312  thus supplement the pattern of the row electrodes  112  in a continuous fashion. The row electrodes  312  are separated by areas  318 , but are connected to each other via conductive layers  324  formed on an insulating layer  332 . 
       FIG. 5  depicts a perspective view of a substrate  510  in which conductive patterns  512  are formed on the substrate  510  to electrically connect the corresponding column electrodes  114 , according to an embodiment. This embodiment simplifies the manufacturing process by eliminating the need to construct vias and conductive patterns in the flex circuit  300 , as shown in  FIG. 3   c . The substrate  510  may also be provided with conductive patterns  514 ,  516 , which correspond to conductive patterns  320 ,  322  of  FIG. 3   c . In order to insulate the conductive patterns  512  from the row electrodes  112  near the region of the area  116 , the substrate may also be provided with layers of insulating material  518  to cover the conductive patterns  512 . 
     As previously stated, the touch sensor using the flex circuit shown in  FIG. 1   a  may operate with self capacitance or mutual capacitance.  FIG. 6  depicts a perspective diagram of a flex circuit  600  of a capacitive sensor using an alternative form of mutual capacitance, according to an exemplary embodiment. In this embodiment, multiple row electrodes  612  are provided across multiple column electrodes  614 . The overlap of each row electrode  612  and each column electrode  614  constitutes a capacitor  616 . An insulating layer (not shown) may be provided at the area of the overlap to increase the capacitance of the capacitors  616 . The rows  602  may be driven via a control unit periodically to charge the capacitors  616  and, as the capacitor  616  are discharged, the voltage of the columns  604  are monitored by a sensing unit. As long as no input is applied to the surface of the substrate, a predetermined voltage may be expected at the columns  604 . However, if an input is applied to the surface of the substrate, it may steal away some of the charge at one or more of the nearby capacitors  616 , resulting in a lower voltage being sensed on the corresponding column  604  by the sensing unit. Based on the row  602  being driven and the column  604  having a lower charge than expected, the sensing unit can determine the position of the touch. 
       FIG. 7   a  illustrates an exemplary flex circuit  700  having a notch  702 . The notch  702  displaces or prohibits the placement of electrodes  712 ,  714  in a continuous pattern. Thus, portions of the electrodes  712 ,  714  that cannot be placed on the flex circuit  700  due to the notch  702  are formed on a surface of the substrate  710  facing the flex circuit  700  in a continuous fashion consistent with the pattern of electrodes  712 ,  714 , shown in  FIG. 7   b . The row electrodes  722  and column electrodes  724  correspond to the electrodes  712 ,  714  of the flex circuit  700 . The area  716  also corresponds to the notch  702  of the flex circuit  700 . In one embodiment, the area  716  may be covered with insulating material to prevent electrical shortage between the electrodes  722 ,  724  and any modules placed inside the notch  702 . In addition, a layer of insulating material  718  may be provided between the electrodes  722 ,  724 . 
     According to an embodiment, the arrangement of electrodes shown in  FIG. 6  can be obtained by forming all the row electrodes on the flex circuit and forming all columns on a surface of the substrate facing the flex circuit. An insulating layer is also formed on the row electrodes. Thereafter, the substrate is placed on the insulating layer such that the overlap of the rows and columns creates the touch sensing capacitors. 
       FIG. 8  provides a cross-sectional view of the capacitive sensor according to this embodiment. As shown in  FIG. 8 , the row electrodes  812  are formed on the flex circuit  800  and the column electrodes  814  are formed on a surface of the substrate  810  facing the flex circuit  800 . The insulating layer  818  is provided between the row electrodes  812  and the column electrodes  814 . Since in this embodiment the column electrodes need not be etched on the flex circuit, this embodiment simplifies the manufacturing process of the touch sensor. 
       FIG. 9   a  illustrates a perspective view of a circular flex circuit  900  capacitive sensor according to yet another embodiment. According to this embodiment, the flex circuit  900  includes electrodes  902   a - 902   n  arranged on a first surface of the flex circuit  900 . Each electrode  902   a - 902   n  includes a via  904  from the electrodes  902   a - 902   n  to a second surface of the flex circuit  900 . The second surface of the flex circuit  900 , as shown in  FIG. 9   b , includes traces  906 , each coupled individually to one of the electrodes  902   a - 902   n  via one of the vias  904 . A substrate (not shown), which may be made of, for example, glass, plastic, plastic, glass, PET material, ceramics, or other material is placed on the first surface of the flex circuit  900 . A controller or processor coupled to the traces  906  can track the position of an input such as a fingertip applied to the surface of the substrate. 
       FIG. 10   a  depicts a perspective view of a circular flex circuit  1000 , in which a notch  1004  represents a portion of flex circuit  1000  that is physically removed or is a portion of flex circuit  1000  that is occupied by another module. In order to obtain a complete electrode pattern as shown in  FIG. 9   a , the electrodes that may have occupied notch area  1004  on the flex circuit  1000  to complete the electrode pattern are formed on a surface of the substrate  1010 , shown in  FIG. 10   b . The electrodes  1012   a ,  1012   j ,  1012   k  and  1012   n  correspond and electrically connect to the electrodes  1002   a ,  1002   j ,  1002   k  and  1002   n , respectively, all of which have been cut off on the flex circuit  1000 . The area  1014  also corresponds to the notch  1004  of the flex circuit  1000 . In one embodiment, the area  1014  may be covered with insulating material to prevent electrical shortage between the electrodes  1012   a ,  1012   j ,  1012   k  and  1012   n  and any module placed inside the notch  1004  of the flex circuit  1000 . 
       FIG. 11  illustrates an example of a simplified block diagram of a computing system  1039 , according to one aspect. The computing system may generally include input device  1040  operatively connected to computing device  1042 . By way of example, the computing device  1042  can correspond to a computer, PDA, media player or the like. As shown, input device  1040  may include input device  1040  can generally correspond to the capacitive sensor  1044 , which may correspond to the any of the aforementioned embodiments, and one or more movement detectors  1046 . The capacitive sensor  1044  can be configured to generate tracking signals and movement detector  1046  can be configured to generate a movement signal when the capacitive sensor is depressed. Although the capacitive sensor  1044  may be widely varied, in this embodiment, capacitive sensor  1044  can include capacitance sensors  1048  and control system  1050  (which can generally correspond to the sensor controllers described above) for acquiring position signals from sensors  1048  and supplying the signals to computing device  1042 . Control system  1050  can include an application specific integrated circuit (ASIC) that can be configured to monitor the signals from sensors  1048 , to compute the absolute location, angular location, direction, speed and/or acceleration of the monitored signals and to report this information to a processor of computing device  1042 . Movement detector  1046  may also be widely varied. In this embodiment, however, movement detector  1046  can take the form of a switch that generates a movement signal when the capacitive sensor  1044  is depressed. Movement detector  1046  can correspond to a mechanical, electrical or optical style switch. In one particular implementation, movement detector  1046  can be a mechanical style switch that includes protruding actuator  1052  that may be pushed by the capacitive sensor  1044  to generate the movement signal. By way of example, the switch may be a tact or dome switch. 
     Both the capacitive sensor  1044  and movement detector  1046  can be operatively coupled to computing device  1042  through communication interface  1054 . The communication interface provides a connection point for direct or indirect connection between the input device and the electronic device. Communication interface  1054  may be wired (wires, cables, connectors) or wireless (e.g., transmitter/receiver). 
     Referring to computing device  1042 , it may include processor  1057  (e.g., CPU or microprocessor) configured to execute instructions and to carry out operations associated with computing device  1042 . For example, using instructions retrieved from memory, the processor can control the reception and manipulation of input and output data between components of computing device  1042 . Processor  1057  can be configured to receive input from both movement detector  1046  and the capacitive sensor  1044  and can form a signal/command that may be dependent upon both of these inputs. In most cases, processor  1057  can execute instruction under the control of an operating system or other software. Processor  1057  may be a single-chip processor or may be implemented with multiple components. 
     Computing device  1042  may also include input/output (I/O) controller  1056  that can be operatively coupled to processor  1057 . (I/O) controller  1056  can be integrated with processor  1057  or it may be a separate component as shown. I/O controller  1056  can generally be configured to control interactions with one or more I/O devices that may be coupled to the computing device  1042 , as for example input device  1040  and orientation detector  1055 , such as an accelerometer. I/O controller  1056  can generally operate by exchanging data between computing device  1042  and I/O devices that desire to communicate with computing device  1042 . 
     Computing device  1042  may also include display controller  1058  that can be operatively coupled to processor  1057 . Display controller  1058  can be integrated with processor  1057  or it may be a separate component as shown. Display controller  1058  can be configured to process display commands to produce text and graphics on display screen  1060 . By way of example, display screen  1060  may be a monochrome display, color graphics adapter (CGA) display, enhanced graphics adapter (EGA) display, variable-graphics-array (VGA) display, super VGA display, liquid crystal display (e.g., active matrix, passive matrix and the like), cathode ray tube (CRT), plasma displays and the like. In the illustrated embodiment, the display device corresponds to a liquid crystal display (LCD). 
     In most cases, processor  1057  together with an operating system operates to execute computer code and produce and use data. The computer code and data can reside within program storage area  1062  that may be operatively coupled to processor  1057 . Program storage area  1062  can generally provide a place to hold data that may be used by computing device  1042 . By way of example, the program storage area may include Read-Only Memory (ROM), Random-Access Memory (RAM), hard disk drive and/or the like. The computer code and data could also reside on a removable program medium and loaded or installed onto the computing device when needed. In one embodiment, program storage area  1062  can be configured to store information for controlling how the tracking and movement signals generated by the input device may be used, either alone or in combination for example, by computing device  1042  to generate an input event command, such as a single button press for example. 
       FIG. 12  depicts an exemplary flow process diagram  1200  for manufacturing a capacitive sensor, according to an embodiment. The process  1200  may begin with block  1202  to initialize the manufacturing process. For example, the process  1200  may identify an area of the substrate that overlaps a notch in the flex circuit as previously described. The process  1200  may then form one or more electrodes on a surface of the flex circuit, block  1204 . The process  1200  may also form at least one electrode on a surface of the substrate, block  1206 . The electrodes formed on the substrate may be formed within an area of the substrate identified as overlapping the notch. An insulating layer may also be formed, either on the first set of electrodes, or on the second set of electrodes, such that when the flex circuit and the substrate are placed together, the insulating layer is arranged between the first and the second set of electrodes. The flex circuit and the substrate are then placed together such that the flex circuit electrodes and the substrate electrodes are securely positioned between the flex circuit and the substrate, block  1208 . The process  1200  may then end at block  1210 . 
     While various embodiments have been described, there are alterations, permutations, and equivalents, which fall within the scope of the claims. It should be noted that there are many alternative ways of implementing the disclosed methods and apparatuses. It is therefore intended that the following appended claims be interpreted as including all such alterations, permutations, and equivalents.

Metadata:
Filing Date: 20080925
Publication Date: 20140826
Grant Date: 20140826
Priority Date: 20080925
Inventors: LYON BENJAMIN
FISHER JOSEPH
RATHNAM LAKSHMAN
Assignee: APPLE INC
CPC Classifications: [{"code": "G06F2203/04111", "inventive": false, "first": false, "tree": "[]"}, {"code": "H03K17/9622", "inventive": true, "first": true, "tree": "[]"}, {"code": "H03K2217/960755", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T29/43", "inventive": false, "first": false, "tree": "[]"}, {"code": "H03K17/9622", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F2203/04111", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/0445", "inventive": true, "first": false, "tree": "[]"}, {"code": "H03K2217/960755", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/0446", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0446", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0445", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 41683453