PATENT DOCUMENT

Publication Number: US-9360967-B2
Application Number: US-48228606-A
Country: US
Kind Code: B2

Title: Mutual capacitance touch sensing device

Abstract:
A mutual capacitive touch sensing device is disclosed. The touch sensing device includes a mutual capacitive sensing controller having a plurality of distinct drive lines and a plurality of distinct sense lines; a source for driving a current or voltage separately though each drive line; and a mutual capacitance sensing circuit that monitors the capacitance at the sensing lines. The touch sensing device also includes a plurality of independent and spatially distinct mutual capacitive sensing nodes set up in a non two dimensional array. Each node includes a drive electrode that is spatially separated from a sense electrode. The drive electrode is coupled to one of the drive lines and the sense electrode is coupled to one of the sense lines. Each node is set up with a different combination of drive and sense line coupled thereto.

Claims:
What is claimed is: 
     
       1. A touch sensing device, comprising:
 a mutual capacitive sensing controller having a plurality of distinct drive lines and a plurality of distinct sense lines, a source for driving a current or voltage separately though each drive line, a mutual capacitance sensing circuit that monitors the capacitance at the sensing lines; 
 a plurality of independent and spatially distinct mutual capacitive sensing nodes set up in a non two dimensional array, each node including a drive electrode that is spatially separated from a sense electrode, the drive electrode and the sense electrode being configured to capacitively couple a drive line and a sense line, 
 the plurality of drive lines configured to carry current from the controller to the nodes, 
 the plurality of sense lines configured to carry current from the plurality of nodes to the controller, 
 wherein the nodes comprise multiple node groups, at least a first of the node groups comprising multiple nodes, each node in a node group being associated with a sense line that is common to all nodes in the group and a drive line that is not common to any other node in the group, one node in each node group being associated with a drive line that is common to all node groups. 
 
     
     
       2. The touch sensing device as recited in  claim 1  wherein the nodes are positioned next to one another in succession along a prescribed path. 
     
     
       3. The touch sensing device as recited in  claim 2  wherein the nodes form a linear path. 
     
     
       4. The touch sensing device as recited in  claim 2  wherein the nodes form a circular path. 
     
     
       5. The touch sensing device as recited in  claim 4  wherein the nodes represent angular input areas disposed around a circle. 
     
     
       6. The touch sensing device as recited in  claim 2  wherein the nodes are placed in an open loop arrangement. 
     
     
       7. The touch sensing device as recited in  claim 2  wherein the nodes are placed in a closed loop arrangement. 
     
     
       8. The touch sensing device as recited in  claim 1  wherein a portion of the nodes form a scrolling region. 
     
     
       9. The touch sensing device as recited in  claim 1  wherein a portion of the nodes form buttons that represent distinct button functions. 
     
     
       10. The touch sensing device as recited in  claim 1  further including a filter that rejects parasitic capacitance effects so that a clean representation of the charge transferred across the node is outputted. 
     
     
       11. The touch sensing device as recited in  1  wherein the nodes include a cover film, an electrode layer and a substrate, the cover film being disposed over the electrode layer, the electrode layer being disposed over the substrate, the electrode layer including the drive and sense electrodes. 
     
     
       12. The touch sensing device as recited in  1  wherein the drive and sense electrodes are juxtaposed plates. 
     
     
       13. The touch sensing device as recited in  1  wherein the drive and sense electrode are interleaved with one another. 
     
     
       14. The touch sensing device as recited in  1  further including a floating electrode disposed over and spatially separated from the electrode pair of the node. 
     
     
       15. The touch sensing device as recited in  1  wherein the mutual capacitance sensing circuit continuously monitors all the sensing lines at the same time. 
     
     
       16. The touch sensing device as recited in  1  wherein the mutual capacitance sensing circuit monitors all the sensing lines sequentially. 
     
     
       17. The touch sensing device as recited in  1  wherein the number of nodes is equal to the number of drive lines multiplied by the number of sense lines. 
     
     
       18. The touch sensing device as recited in  17  wherein the number of drive lines is equal to the number of sense lines. 
     
     
       19. The touch sensing device as recited in  17  wherein the number of drive lines is different than the number of sense lines. 
     
     
       20. The touch sensing device as recited in  1  wherein the number of nodes is less than the number of drive lines multiplied by the number of sense lines. 
     
     
       21. A mutual capacitive sensing method, comprising:
 separately driving a voltage or current through each of multiple drive lines; 
 capacitively coupling current between mutual capacitive sensing nodes comprising drive electrodes that are coupled to the driven drive line and corresponding sense electrodes that are coupled to different sense lines, 
 the nodes forming multiple node groups, each of the multiple groups comprising multiple nodes, each node in a group being associated with a sense line that is common to all nodes in the group and a drive line that is not common to any other node in the group, one node in each group being associated with a drive line that is common to all groups, 
 detecting with a mutual capacitance sensing circuit capacitance at drive and sense electrode pairs through each sense line each time a drive line is driven; 
 determining which electrode pairs have been touched based on detected capacitance; and 
 performing actions based on which electrode pairs have been touched. 
 
     
     
       22. The method as recited in  claim 21  further including filtering parasitic capacitance created by non driven electrode pairs. 
     
     
       23. A touch sensing device that operates via mutual capacitance, comprising:
 multiple mutual capacitance sensing nodes, 
 each mutual capacitance sensing node including a drive electrode that is spatially separated and juxtaposed next to a sense electrode, the drive electrode being coupled to a drive line and the sense electrode being coupled to a sense line of a mutual capacitance sensing circuit, and a floating electrode disposed over and spatially separated from the drive electrode and the sense electrode, 
 the nodes being arranged in multiple groups, 
 each of the multiple groups comprising multiple nodes, 
 each node in a group being associated with a sense line that is common to all nodes in the group and a drive line that is not common to any other node in the group, 
 one node in each group being associated with a drive line that is common to all groups. 
 
     
     
       24. A mutual capacitance touch sensing device, comprising:
 a plurality of mutual capacitance sensing nodes arranged in a non 2D array and coupled to drive lines and sense lines, each node comprising an electrode pair of drive electrode and sense electrode configured to capacitively couple a drive line and a sense line, at least one of the drive lines configured to carry a current to the drive electrode of the node, and at least one of the sense lines configured to carry a current from the sense electrode of the node to a mutual capacitance sensing circuit indicating a change in capacitance at the node, 
 the nodes comprising node groups, each node in a node group being associated with a sense line that is common to all nodes in the group and a drive line that is not common to any other node in the group, one node in each node group being associated with a drive line that is common to all node groups. 
 
     
     
       25. The mutual capacitance touch sensing device of  claim 24 , wherein each node in a node group comprises a drive electrode coupled to different ones of the drive lines and a sense electrode coupled to a same one of the sense lines, and each node group comprises a node coupled to a same one of the drive lines. 
     
     
       26. A touch sensing device comprising:
 a controller, 
 multiple nodes, 
 multiple drive lines configured to carry current from the controller to the nodes, 
 multiple sense lines configured to carry current from the multiple nodes to the controller, 
 each of the multiple nodes comprising a drive electrode and a sense electrode, the drive electrode and the sense electrode being configured to capacitively couple a drive line and a sense line, 
 the nodes being arranged in multiple groups, 
 each of the multiple groups comprising multiple nodes, 
 each node in a group being associated with a sense line that is common to all nodes in the group and a drive line that is not common to any other node in the group, 
 one node in each group being associated with a drive line that is common to all groups. 
 
     
     
       27. A touch sensing device, comprising:
 a mutual capacitive sensing controller having a plurality of distinct drive lines and a plurality of distinct sense lines, a source for driving a current or voltage separately though each drive line, a mutual capacitance sensing circuit that monitors the capacitance at the sensing lines; 
 a plurality of independent and spatially distinct mutual capacitive sensing nodes set up in a non two dimensional array, each node including a drive electrode that is spatially separated from a sense electrode, the drive electrode and the sense electrode being configured to capacitively couple a drive line and a sense line, 
 the plurality of drive lines configured to carry current from the controller to the nodes, 
 the plurality of sense lines configured to carry current from the plurality of nodes to the controller, 
 wherein the nodes comprise multiple adjacent node groups, at least a first of the adjacent node groups comprising multiple nodes, each node in a node group being associated with a sense line that is common to all nodes in the group and a drive line that is not common to any other node in the group, one node in each node group being associated with a drive line that is common to all node groups. 
 
     
     
       28. A touch sensing device comprising:
 a controller, 
 multiple nodes, 
 multiple drive lines configured to carry current from the controller to the nodes, 
 multiple sense lines configured to carry current from the multiple nodes to the controller, 
 each of the multiple nodes comprising a drive electrode and a sense electrode, the drive electrode and the sense electrode being configured to capacitively couple a drive line and a sense line, 
 the nodes being arranged in multiple adjacent groups, 
 each of the multiple adjacent groups comprising multiple nodes, 
 each node in a group being associated with a sense line that is common to all nodes in the group and a drive line that is not common to any other node in the group, 
 one node in each group being associated with a drive line that is common to all groups.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is related to the following applications, all of which are herein incorporated by reference: 
     U.S. patent application Ser. No. 10/188,182, titled “TOUCH PAD FOR HANDHELD DEVICE”, filed Jul. 1, 2002; U.S. patent application Ser. No. 10/722,948, titled “TOUCH PAD FOR HANDHELD DEVICE”, filed Nov. 25, 2003; U.S. patent application Ser. No. 10/643,256, titled “MOVABLE TOUCH PAD WITH ADDED FUNCTIONALITY”, filed Aug. 18, 2003; U.S. patent application Ser. No. 10/840,862, titled “MULTIPOINT TOUCHSCREEN”, filed May 6, 2004; U.S. patent application Ser. No. 11/057,050, titled “DISPLAY ACTUATOR”, filed Feb. 11, 2005; and U.S. patent application Ser. No. 11/115,539, titled “HAND HELD ELECTRONIC DEVICE WITH MULTIPLE TOUCH SENSING DEVICES”. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to touch sensing devices used in portable electronic devices. More particularly, the present invention relates to an improved mutual capacitance sensing touch device. 
     2. Description of the Related Art 
     There are many factors that determine the size of compact portable electronic devices such as laptops, PDAs, media players, cell phones, etc. In most cases, the size of the portable electronic device is limited by the size of the operational components used therein. These components include for example microprocessor chips, printed circuit boards, displays, memory chips, hard drives, batteries, interconnectivity circuitry, indicators, input mechanisms and the like. As such, there is a desired to make these operational components smaller and smaller while maintaining or increasing their power and functionality to perform operations as well as decreasing their cost. The placement of these components inside the electronic device is also a factor in determining the size of the portable electronic device. For thin devices such as cell phones, PDAs and media players, stacking operational components on top of each other is limited and therefore the operational components may be placed side by side. In some cases, the operational components may even communicate through wires or flex circuits so that they may be spaced apart from one another (e.g., not stacked). 
     There exist today many styles of input mechanisms for performing operations in a portable electronic device. The operations generally correspond to moving objects and making selections. By way of example, the input devices may include buttons, keys, dials, wheels, mice, trackballs, touch pads, joy sticks, touch screens and the like. Touch devices such as touch buttons, touch pads and touch screens are becoming increasingly popular in portable electronic devices because of their ease and versatility of operation, their declining price as well as their space saving ability (e.g., planarity). Touch devices allow a user to make selections and move objects by simply moving their finger (or stylus) relative to a touch sensing surface. In general, the touch device recognizes a touch and in some circumstances the characteristics of the touch and a host controller of the portable electronic device interprets the touch data and thereafter performs action based on the touch data. 
     There are several types of technologies for implementing a touch device including for example resistive, capacitive, infrared, surface acoustic wave, electromagnetic, near field imaging, etc. 
     Capacitive touch sensing devices have been found to work particularly well in portable electronic devices. Generally speaking, whenever two electrically conductive members come close to one another without actually touching, their electric field interact to form capacitance. In the case of a capacitive touch device, as an object such as a finger approaches the touch sensing surface, a tiny capacitance forms between the object and the sensing points in close proximity to the object. By detecting changes in capacitance at each of the sensing points and noting the position of the sensing points, the sensing circuit can recognize multiple objects and determine the location, pressure, direction speed and acceleration of the object as it is moved across the touch surface. 
     Although capacitive sensing devices have been found to work particularly well in portable electronic devices, improvements to form, feel and functionality are still desired. For example, improvements that help produce a better portable electronic device. 
     SUMMARY OF THE INVENTION 
     The invention relates, in one embodiment, to a touch sensing device. The touch sensing device includes a mutual capacitive sensing controller having a plurality of distinct drive lines and a plurality of distinct sense lines, a source for driving a current or voltage separately though each drive line, a mutual capacitance sensing circuit that monitors the capacitance at the sensing lines. The touch sensing device also includes a plurality of independent and spatially distinct mutual capacitive sensing nodes set up in a non two dimensional array. Each node includes a drive electrode that is spatially separated from a sense electrode. The drive electrode is coupled to one of the drive lines and the sense electrode is coupled to one of the sense lines. Each node is set up with a different combination of drive and sense line coupled thereto. 
     The invention relates, in another embodiment, to a touch sensing device that operates via mutual capacitance. The touch sensing device includes a mutual capacitance sensing node including a drive electrode that is spatially separated and juxtaposed next to a sense electrode. The drive electrode is coupled to a drive line and the sense electrode is coupled to a sense line of a mutual capacitance sensing circuit. 
     The invention relates, in another embodiment, to a mutual capacitive sensing method. The method includes separately driving a voltage or current through each drive line. The method also includes capacitively coupling current between drive electrodes that are coupled to driven drive line and corresponding sense electrodes that are coupled to sense lines. The method further includes detecting capacitance at electrode pairs through each sense line each time a drive line is driven. The method additionally includes determining which electrode pairs have been touched based on detected capacitance. Moreover, the method includes performing actions based on which electrode pairs have been touched. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention may best be understood by reference to the following description taken in conjunction with the accompanying drawings in which: 
         FIG. 1  is a circuit diagram of a mutual capacitive sensing input device, in accordance with one embodiment of the present invention. 
         FIG. 2  is a circuit diagram of a filter arrangement of a mutual capacitance sensing circuit, in accordance with one embodiment of the present invention. 
         FIG. 3A  is a block diagram of a mutual capacitive sensing circuit, in accordance with one embodiment of the present invention. 
         FIG. 3B  is a block diagram of a mutual capacitive sensing circuit, in accordance with one embodiment of the present invention. 
         FIG. 4  is a diagram of a mutual capacitive sensing node, in accordance with one embodiment of the present invention. 
         FIG. 5  is a diagram of a mutual capacitive sensing node, in accordance with one embodiment of the present invention. 
         FIG. 6  is a diagram of a mutual capacitive sensing node, in accordance with one embodiment of the present invention. 
         FIGS. 7A and 7B  show the embodiment of  FIG. 6  in circuit diagram form, in accordance with one embodiment of the present invention. 
         FIG. 8  is a diagram of a circular touch device, in accordance with one embodiment of the present invention. 
         FIG. 9  is a diagram of a linear touch device, in accordance with one embodiment of the present invention. 
         FIG. 10  is a diagram of another type of linear touch device, in accordance with one embodiment of the present invention. 
         FIG. 11  is a diagram of a combined touch device, in accordance with one embodiment of the present invention. 
         FIG. 12  is a diagram of a touch device that includes a touch region and one or more distinct buttons, in accordance with one embodiment of the present invention. 
         FIG. 13  is a diagram of a touch device that includes a touch region and one or more distinct buttons, in accordance with one embodiment of the present invention. 
         FIG. 14  is a diagram of a touch device that includes a touch region and one or more distinct buttons, in accordance with one embodiment of the present invention. 
         FIG. 15  is diagram of a touch device that only includes a button arrangement, in accordance with one embodiment of the present invention. 
         FIG. 16  is a diagram of a touch assembly, in accordance with one embodiment of the present invention. 
         FIG. 17  is a block diagram of an exemplary electronic device, in accordance with one embodiment of the present invention. 
         FIG. 18  is a perspective diagram of a media player, in accordance with one embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The simplicity of capacitance allows for a great deal of flexibility in design and construction of the sensing device. By way of example, the sensing device may be based on self capacitance or mutual capacitance. 
     In self capacitance, each of the sensing points is provided by an individually charged electrode. As an object approaches the surface of the touch device, the object capacitively couples to those electrodes in close proximity of the object thereby stealing charge away from the electrodes. The amount of charge in each of the electrodes are measured by the sensing circuit to determine the positions of objects as they touch the touch sensitive surface. 
     In mutual capacitance, the sensing device typically includes a two-layer grid of spatially separated wires. In the simplest case, the upper layer includes lines in rows while the lower layer includes lines in columns (orthogonal). The sensing points are provided at the intersections of the rows and columns. During operation, the rows are charged and the charge capacitively couples to the columns at the intersection. As an object approaches the surface of the touch device, the object capacitively couples to the rows at the intersections in close proximity to the object thereby stealing charge away from the rows and therefore the columns as well. The amount of charge in each of the columns is measured by the sensing circuit to determine the positions of multiple objects when they touch the touch sensitive surface. 
     Each of these capacitive sensing methodologies has advantages and disadvantages that must be taken into account when designing a capacitive touch input device. For example, while self capacitance may be arranged in a wide variety of orientations (both 2D and non 2D arrays), they tend to produce a large number of I/O contacts especially as the resolution of the touch pad is increased (each electrode requires a separate I/O contact). The large number of I/O contacts create design difficulties especially in portable devices that are small. For example, they may require large chips and/or additional chips in order to process the large number of I/O contacts. These chips however take up valuable space inside the device and create stack up such that the device needs to be made larger to accommodate the chip(s). Furthermore, routing the I/O through traces from the electrodes to the chips may further exacerbate this problem as well as create new ones. 
     Unlike self capacitance, mutual capacitance can reduce the number of I/Os for the same resolution (sometimes by a factor of two). However, conventional mutual capacitance circuits are fixed to a 2D array of rows and columns (e.g., x and y) thus preventing uniquely shaped touch surfaces (e.g., non 2D arrays). Furthermore, while rows and columns that are used in mutual capacitive sensing circuits may be well suited for tracking or pointing, this arrangement may not be as well suited for other less complicated tasks associated with some application specific portable electronic devices. This is especially true when you consider the desire to maintain a small form factor with limited I/O contacts. Examples of less complicated tasks may include for example selection tasks such as buttoning and object movement tasks such as scrolling. Another problem with mutual capacitance may be in its accuracy due to parasitic capacitance that can be created using this methodology. Yet another problem with both technologies may be that they are only capable of reporting a single point when multiple objects are placed on the sensing surface. That is, they lack the ability to track multiple points of contact simultaneously. 
     The invention therefore pertains to improved features for touch devices used in portable electronic devices and more particularly touch devices that are based on capacitance. One aspect of the invention relates to a mutual capacitive sensing touch device that includes capacitive sensing nodes that reduce the number of I/O contacts and that are capable of being positioned in any orientation (e.g., 2D arrays are not a requirement). In fact, in one implementation, the capacitive sensing nodes are placed in a non 2D array. This presents a paradigm shift in the way that designers think about mutual capacitive sensing touch devices. In one example, the capacitive sensing nodes are positioned at angular positions in a circular manner. 
     These and other embodiments of the invention are discussed below with reference to  FIGS. 1-18 . 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 invention extends beyond these limited embodiments. 
       FIG. 1  is a circuit diagram of a mutual capacitive touch sensing input device  10 , in accordance with one embodiment of the present invention. The mutual capacitive touch sensing input device  10  is configured to utilize a limited number of I/O contacts while maximizing its resolution, minimizing its size, and providing a multiplicity of orientations including non 2D arrays. Because of this, the input device may for example be placed in a variety of portable electronic devices and serve a wide variety of functions including for example scrolling, parameter control and buttoning. In fact, the input device works particularly well in small compact handheld devices such as cell phones and media players (e.g., music players, game players, video players, etc.). 
     The input device  10  includes a mutual capacitive sensing controller  12  that communicates with a touch sensitive element  14 . The touch sensitive element  14  includes a plurality of independent and spatially distinct mutual capacitive sensing nodes  20  that are positioned about a touch surface of the touch sensitive element  14 . The nodes  20  are dispersed such that each node  20  represents a different position on the touch surface. During operation, each of the mutual capacitive sensing nodes  20  produces a capacitance, and the mutual capacitive sensing controller  12  detects changes in the capacitance at each of the nodes  20 . This information is used to determine touch events. In most cases, the nodes  20  are electrically coupled to the sensing controller  12  through traces or other well-known routing technologies such as those associated with printed circuit boards, flex circuits and integrated chips. 
     The touch sensitive element  14  can be widely varied. In some cases, it is mounted to or within a housing of the portable electronic device. For example, the element  14  may be utilized in a touch pad that is mounted within an opening in the housing of the portable electronic device. The touch pad may be a fixed to the portable electronic device or it may be movable so as to engage one or more actuators such as switches. In other cases, the touch sensitive element  14  is a thin layer applied over a component of the portable electronic device including for example the housing or a display of the portable electronic device. By way of example, the element  14  may be used to create a touch screen (e.g., over laid on top of a display). The touch screen may be a fixed to the portable electronic device or it may be movable so as to engage one or more actuators such as switches. Alternatively, the element  14  may be a portion of the housing (e.g., nodes are embedded inside the housing or adhered to the inside surface of the housing of the portable electronic device). Examples of various ways of situating the touch sensitive element  14  relative to an electronic device can be found in U.S. patent application Ser. Nos. 10/188,182, 10/722,948, 10/643,256, 10/840,862, 11/057,050 and 11/115,539, which are herein incorporated by reference. 
     The mutual capacitive sensing controller  12  can also be widely varied. In some cases, the mutual capacitive sensing controller  12  is a separate controller that is operatively coupled to a host controller of a portable electronic device (e.g., for example using a flex circuit or printed circuit board). In other cases the controller  12  is integrated into the host controller of the electronic device. That is, the sensing controller  12  is part of the host controller. Integration may be possible due to the reduced number of I/O contacts required by mutual capacitance technology. 
     Referring to  FIG. 1 , the mutual capacitive sensing controller  12  communicates with the nodes  20  via a plurality of distinct drive lines  16  and a number of distinct sense lines  18 . The drive lines  16  are configured to carry current from the controller  12  to the mutual capacitive coupling nodes  20  and the sensing lines  18  are configured to carry a current from the mutual capacitive coupling nodes  20  to the capacitive controller  12 . The drives lines  16  capacitively couple to each of the sense lines  18  at the plurality of capacitive sensing nodes  20 . Each node  20  is set up with a different combination of drive and sense line  16  and  18 . For example, in the illustrated embodiment, the circuit  10  includes four drive lines  16  and four sense lines  18  thereby forming sixteen individual nodes  20 . The number of nodes  20  is typically the number of drive lines multiplied by the number of sense lines. In some cases, the nodes are formed by an equal number of drive lines and sense lines. For example, the circuit may include the following arrangement of drive/sense-nodes, 2/2-4, 3/3-9, 4/4-16, 5/5-25, 6/6-36, 7/7-49, 8/8-64, 9/9-81, 10/10-100, and so on. In other cases, the nodes are formed by a different number of drive and sense lines. For example, the circuit may include the following arrangement of drive/sense-nodes 2/3-6, 3/5-15, 4/6-24, 5/8-40, 7/9-63, 9/10-90, and so on. It should be further pointed out that in some limited circumstances, the nodes may not equal the number of drive lines multiplied by the number of sense lines. For example, the number of nodes may be smaller than this number. This may be done in cases where the required number of nodes is a primary number [e.g., the designer simply does not make a node(s) even though there is a drive line(s) and sense line(s) to do so]. Accordingly, any number of nodes may be produced. 
     As shown, the drive lines  16  are connected to a voltage source  15  that separately drives the current through each of the driving lines  16 . That is, the stimulus is only happening over one line while all the other lines are grounded. They may be driven similar to a raster scan. The sensing lines  18 , on the other hand, are connected to a mutual capacitive sensing circuit  17  that monitors the sensing lines  18 . In one embodiment, this is accomplished with independent sensing circuits that each monitor an individual sensing line. In this manner, the mutual capacitive sensing circuit  17  is capable of continuously monitoring the sensing lines  18  at the same time. That is, the mutual capacitive sensing circuit  17  is always monitoring the capacitance through the sensing lines  18 . In another embodiment, instead of the sensing lines being all read at the same time by independent circuits, the sensing lines may be sequentially switched to a common sensing circuit and read one after the other (e.g., multiplexing). This tends to reduce the silicon area of the chip but it also increases the scanning time. 
     Although not shown in great detail in  FIG. 1 , each node  20  includes a drive electrode  22  coupled to one of the drive lines  16  and a sense electrode  24  coupled to one of the sense. This may for example be accomplished via traces or other related circuitry. The electrodes  22  and  24  are spatially separated and therefore cooperate to capacitively couple a charge therethrough. The electrodes  22  and  24  may be arranged in a variety of ways. In one implementation, the electrodes  22  and  24  are plates that are juxtaposed next to one another in a side-by-side relationship thereby creating fringe fields when the drive electrode  22  is driven. In another implementation, the spaced apart electrodes  22  and  24  are disposed below an electrically isolated “floating” electrode. These and other embodiments will be described below. 
     Unlike conventional mutual capacitance devices, which have nodes that are fixed to intersection points of upper rows and lower columns, the electrode arrangement disclosed herein allows each node  20  to be placed at any location within a touch surface. This is similar to self capacitance technology that utilizes individual electrodes at each node. However, unlike self capacitance technology, the mutual capacitance technology reduces the number of I/O contacts required for the desired number of nodes. In self capacitance, each node includes a distinct I/O contact and therefore to achieve sixteen nodes, at least seventeen I/O contacts are needed (one is for return ground). In essence, the invention described herein provides the benefits of each type of technology (e.g., nodes that can be placed anywhere while limiting the number of I/O contacts for a given resolution). Furthermore, although the nodes  20  are typically placed on a planar surface, in some circumstances the nodes  20  may be placed on a contoured surface. Moreover, the nodes  20  may be placed on multiple surfaces such as multiple sides of a portable electronic device. 
     Because the node location is not limited, the nodes  20  may be positioned in a conventional 2D array of rows and columns or alternatively they may be positioned in a non 2D array thereby allowing a wide variety of user interfaces to be created. In fact, non 2D arrays may be beneficial in creating user interfaces that better fit portable electronic devices. For example, different orientations of nodes  20  may be used to provide input functionality that is directed at the specific applications of the portable electronic device. The user interfaces may for example include scrolling regions or parameter control regions where nodes are set up in succession along a predetermined path, and/or button regions where individual nodes may represent distinct button functions. With regards to a scrolling or parameter control, the nodes may be placed in an open loop arrangement such as a line, or they may be placed in closed loop arrangement such as a circle. Generally speaking, the nodes can be placed to form any shape whether in a single plane or multiple planes. Examples include squares, rectangles, circles, semi-circles, ovals, triangles, trapezoids, other polygons, pill shapes, S shapes, U shapes, L shapes, star shapes, plus shape, etc. 
     Any number of nodes  20  may be used. The number of nodes  20  is typically determined by the size of the touch device as well as the size of the electrodes  22  and  24  used at the nodes  20 . In many cases, it is desirable to increase the number of nodes  20  so as to provide higher resolution (e.g., more information can be used for such things as acceleration). However, as the number increases, so does the number of I/Os. Therefore a careful balance between resolution and number of I/Os needs to be made when designing the touch device. 
     Furthermore, the size and shape of the nodes  20  may vary according to the specific needs of the touch device. Generally speaking, the nodes  20  can be formed from almost any shape and size. For example they may be formed as squares, rectangles, circles, semi-circles, ovals, triangles, trapezoids, other polygons and or more complicated shapes such as wedges, crescents, stars, lightning bolts, etc. In some cases, at least a portion and in some cases all the nodes  20  are identical. That is, they have the same size and shape. In other cases, at least a portion and in some cases all the nodes  20  have different sizes and/or shapes. For example, a first set of nodes  20  may have a first shape and a second set of nodes  20  may have a second shape that is different than the first shape. The configuration is typically dependent on the functionality that the touch device provides. For example, scrolling or parameter control nodes may be configured similarly within a scrolling or parameter control region, and button nodes may be configured differently than scrolling or parameter control nodes and each other. In essence, the size and shape depends on the desired functionality. If the functionality is the same then the size and shape the nodes tend to be same. If one functionality is more dominant than another functionality, then the size and shape may be matched accordingly. In some cases, the size of the nodes corresponds to about the size of a fingertip. In other cases, the size of the nodes are smaller than the size of a finger tip so as to improve the resolution of the touch device (the finger can influence two of more nodes at anyone time thereby enabling interpolation). 
     During operation, the controller  12  directs a voltage to be applied to each drive line  16  separately. This happens sequentially until all the lines have been driven. For example, a voltage may first be applied to the first drive line  16 A, then the second drive line  16 B, then the third drive line  16 C and then the forth drive line  16 D. Once all the lines have been driven, the sequence starts over (continuously repeats). On the other hand, in one embodiment, the capacitive sensing circuit  17  of the controller  12  senses all of the sensing lines  18  in parallel. That is, each time a drive line is driven, each of the sensing lines  18 A- 18 D are monitored. This is typically accomplished with independent circuits. Alternatively, in another embodiment, each sense line may be monitored in sequence, to share the same sensing circuit (e.g. multiplexing each line to the sense circuit on-chip). 
     More particularly, because of the capacitive coupling, when a current is driven through a driving line  16 , the current is carried through to the sensing lines  18 A-D at each of the nodes  20  coupled to the driving line  16 . The sensing circuit  17  monitors the change in capacitance that occurs at each of the nodes  20  via the sensing lines  18 A-D. The positions where changes occur and possibly the magnitude of those changes are used to help recognize touch events. 
     When no object is present, the capacitive coupling at the node  20  stays fairly constant. When an object such as a finger is placed proximate the node  20 , the capacitive coupling changes through the node  20 . The object effectively shunts some of the field away so that the charge projected across the node  20  is less, i.e., the object steals charge thereby affecting the capacitance. The change in capacitive coupling changes the current that is carried by the sensing lines  18 A-D. The capacitance circuit  17  notes the current change and the particular node  20  where the current change occurred and reports this information in a raw or in some processed form to the host controller of the portable electronic device. 
     Although not shown in great detail in  FIG. 1 , the circuit  17  may additionally include filters for eliminating parasitic capacitance, which may for example be created when nodes, contacts and/or routing circuitry are located closely together. Generally speaking the filter rejects stray capacitance effects so that a clean representation of the charge transferred across the node is outputted (and not anything in addition to that). That is the filter produces an output that is not dependent on the parasitic capacitance, but rather on the capacitance at the node  20 . As a result, a more accurate output is produced. In one embodiment, the filters are embodied as inverting amplifiers that null the input voltage through each sense line. 
       FIG. 2  is a diagram of an inverting amplifier  40 , in accordance with one embodiment of the present invention. The inverting amplifier  40  may be used in the circuit  17  of  FIG. 1  in order to reduce the parasitic capacitance. As shown, the inverting amplifier includes a non inverting input that is held at a constant voltage (in this case ground), an inverting input that is coupled to the node and an output that is coupled to the capacitive sensing circuit  17 . The output is coupled back to the inverting input through a capacitor and/or resistor. During operation, the input from the node may be disturbed by stray capacitance effects, i.e., parasitic capacitance. If so, the inverting amplifier is configured to drive the input back to the same voltage that it had been previously before the stimulus. As such, the value of the parasitic capacitance doesn&#39;t matter. 
     Analyzed from the circuit standpoint, the charge Q when injected into the circuit is proportional to the change in voltage. Because the change in voltage is nulled, the input is kept at a constant voltage, and therefore the net change that goes in and out of the node is zero, which means the error signal at output of op amp is zero contribution related to the parasitics caused by other nodes. 
       FIG. 3A  is a block diagram of a capacitive sensing circuit  60 , in accordance with one embodiment of the present invention. The capacitive sensing circuit  60  may for example correspond to the capacitive sensing circuits described in  FIG. 1 . The capacitive sensing circuit  60  is configured to receive input data from a plurality of sensing points  62  (electrode, nodes, etc.), to process the data and to output processed data to a host controller. 
     The sensing circuit  60  includes a multiplexer  64  (MUX). The multiplexer  64  is a switch configured to perform time multiplexing. As shown, the MUX  64  includes a plurality of independent input channels  66  for receiving signals from each of the sensing points  62  at the same time. The MUX  64  stores all of the incoming signals at the same time, but sequentially releases them one at a time through an output channel  68 . 
     The sensing circuit  60  also includes an analog to digital converter  70  (ADC) operatively coupled to the MUX  64  through the output channel  68 . The ADC  70  is configured to digitize the incoming analog signals sequentially one at a time. That is, the ADC  70  converts each of the incoming analog signals into outgoing digital signals. The input to the ADC  70  generally corresponds to a voltage having a theoretically infinite number of values. The voltage varies according to the amount of capacitive coupling at each of the sensing points  62 . The output to the ADC  70 , on the other hand, has a defined number of states. The states generally have predictable exact voltages or currents. 
     The sensing circuit  60  also includes a digital signal processor  72  (DSP) operatively coupled to the ADC  70  through another channel  74 . The DSP  72  is a programmable computer processing unit that works to clarify or standardize the digital signals via high speed mathematical processing. The DSP  74  is capable of differentiating between human made signals, which have order, and noise, which is inherently chaotic. In most cases, the DSP performs filtering and conversion algorithms using the raw data. By way of example, the DSP may filter noise events from the raw data, calculate the touch boundaries for each touch that occurs on the touch screen at the same time, and thereafter determine the coordinates for each touch event. The coordinates of the touch events may then be reported to a host controller where they can be compared to previous coordinates of the touch events to determine what action to perform in the host device. 
     Another embodiment of the capacitive sensing circuit is shown in  FIG. 3B . This embodiment is similar to  FIG. 3A , but more simplified. In this embodiment, channel is followed by its own dedicated demodulator and A/D converter. The demodulator is basically an analog multiplier with one input tied to the pulse generator signal, and the other input tied to the output of the channel charge amplifier. The output of the demodulator feeds the A/D converter, which is a delta-sigma type of converter. 
     In one implementation of this embodiment, the circuit waits until a timer (or host controller) indicates that a sensing cycle should begin. Thereafter, a pulse train is sent to the first drive line (e.g., 12 pulses which are each 3 uS period). Then, synchronous charge coupling is sensed on all sense lines. This may for example be accomplished by demodulating the charge transferred to the sense lines using the pulse train phase and frequency reference. Thereafter, an A/D conversion is performed on the sensed synchronous charge transfer for each sense line. Then, each data is associated with the specific capacitor being sensed, which is identified by the combination of the particular drive line and sense line which are connected to the capacitor of interest. Then, the data from the A/D converter is signal processed using techniques such as baseline subtraction, low pass filter, etc. Thereafter, the processed data is communicated to the host, or is act on in an appropriate manner. This method may be repeated for each drive line. 
     A variety of nodes that can be utilized in the embodiments described above will now be described in conjunction with  FIGS. 4-7 . It should be appreciated that this are given by way of example and not by way of limitation as the invention can extend beyond these limited embodiments. 
       FIG. 4  is a diagram of a mutual capacitive sensing node  100 , in accordance with one embodiment of the present invention. The node  100  is formed from various layers including a cover film  102 , an electrode layer  104  and a substrate  106 . The cover film  102  is disposed over the electrode layer  104  and the electrode layer  104  is disposed over the substrate  106 . The electrode layer  104  includes a drive electrode  108  and a sense electrode  110  that are spaced apart from one another in order to electrically isolate them from each other. The drive electrode  108  is coupled to a drive line and the sense electrode  110  is coupled to a sense line. When the drive electrode  108  is driven with a voltage or current, the voltage or current is capacitively coupled to the sense electrode  110  via fringe fields  112  that come up through the cover film  102 . When an object is placed over the node  100 , the finger shortcuts or steals some of the field lines  112  away effectively reducing the capacitance that is coupled through the node  100 . 
     The electrodes  108  and  110  may be formed from almost any shape and size. For example they may be formed as squares, rectangles, circles, semi-circles, ovals, triangles, trapezoids, other polygons and or more complicated shapes such as wedges, crescents, stars, lightning bolts, etc. The size and shape of the electrodes  108  and  110  typically depends on the size and shape of the node  100 . In some cases, the electrodes  108  and  110  are equal pairs having the same size and shape. For example, the node  100  may be divided equally in half. In other cases, the electrodes  108  and  110  are disparate pairs having different sizes and/or shapes. For example, the drive electrode  108  may have a first size and/or shape and the sense electrode  110  may have a second size and/or shape that is different than the first shape. By way of example, it may be beneficial to have a larger drive electrode and a smaller sense electrode (or vice versa). 
       FIG. 5  is a diagram of a mutual capacitive sensing node  120 , in accordance with one embodiment of the present invention. The node  120  is similar to the node  100  described in  FIG. 4  except that the drive electrode  108  and sense electrode  110  are interleaved rather than being juxtaposed plates. 
       FIG. 6  is a diagram of a mutual capacitive sensing node  140 , in accordance with one embodiment of the present invention. The node  140  is similar to the nodes  100  or  120  described in  FIGS. 4 and 5  in that it uses spaced apart electrodes  108  and  110 . However, unlike the embodiments described above, the node  140  further includes a floating (electrically isolated) electrode  142  disposed above the electrode pairs  108  and  110 . As shown, the drive and sense electrodes  108  and  110  are disposed underneath a substrate  106 , and the floating electrode  142  is disposed over the substrate  106 . Furthermore, the cover film  102  is disposed over the floating electrode  142 . In this embodiment, the driving current is capacitively coupled to the floating electrode from the driving electrode  108  then its is capacitively coupled to the sense electrode  110 . Moreover, the outer dimension of the floating electrode  142  typically matches the outer dimensions of the electrode pairs  108  and  110 , although in some circumstances it may be desirable to make the outer dimension of the floating electrode  142  smaller or larger than the outer dimension of the electrode pairs  108 / 110 . 
       FIGS. 7A and 7B  show the embodiment of  FIG. 6  in circuit diagram form. In this illustration, C 1  is the capacitance between the drive electrode  108  and the floating electrode  142 , C 2  is the capacitance between the floating electrode  142  and the sense electrode  110 , and C 3  is the capacitance between a finger  144  and the floating electrode  142 . C 3  is the only capacitance that changes (only exists when a finger or other related object is present). 
     For illustration purposes, assume that a typical value for C 1  is 2 pF, C 2  is 2 pF and C 3  is 2 pF. When there is no touch, the capacitance C 1  and C 2  are placed in series thereby creating a total net capacitance of 1 pF. This capacitance is fed through a sense line and read by the capacitance sensing circuit. When there is a touch, the capacitance C 2  and C 3  are first combined together (because the sense electrode is held at virtual ground) then the capacitance C 1  (2 pF) and C 23  (4 pF) are placed in series thereby creating a total net capacitance of (4 pf*2 pf)/(4 pf+2 pf)= 8/6 pf. However, the total charge transfer is split equally between C 2  and C 3 , so the charge transfer through C 2  is ½ of the total, or ⅔ pF. This capacitance is fed through a sense line and read by the capacitance sensing circuit. The capacitance sensing circuit differentiates between a no touch and a touch by checking these values (e.g., no touch=1 pF, touch=something other than 1 pF). The value of the capacitance for a touch may further be used to determine touch pressure as the capacitance typically changes with increased pressure. 
     Referring to all the node designs mentioned above ( FIGS. 4-7 ), the substrate  106  may for example be a printed circuit board or a flexible membrane such as those of a flex circuit or some other suitable material for supporting the electrodes  108  and  110  thereon (e.g., housing of portable electronic device). Furthermore, the electrodes  108  and  110  may be formed from any thin conductive material. By way of example, the electrodes  108  and  110  may be embodied as a metallic foil that is adhered to the substrate  106 , a conductive paint or ink that is coated on the substrate  106 , a conductive material that is printed, deposited or etched on the substrate  106 , plates or bands that are molded or embedded into the substrate  106  or any other suitable arrangement. Moreover, the cover film  102  may be formed from any suitable dielectric material such as glass or plastic. The cover film  102  serves to protect the underlayers and provide a surface for allowing an object to slide thereon. The cover film  102  also provides an insulating layer between the object and the electrode layer  104 . Furthermore, the cover film  102  is suitable thin to allow sufficient electrode coupling. 
     In some cases, the various layers may further be embodied as transparent or semi transparent materials. For example, the conductive material of the electrodes may be formed from indium tin oxide (ITO), the dielectric material of the film may be formed as clear or partially transparent plastic or glass, and the substrate may be formed as clear or partially transparent plastic or glass (e.g., clear Mylar sheet). This may be done to allow visual feedback through the various layers of the touch device. 
     Moreover, the electrode layer  104  may include interconnects for coupling the electrodes  108  and  110  to the driving and sensing lines. Alternatively, the driving and sensing lines may be formed with the electrodes  108  and  110  in the same step/layer. 
     In one implementation, the electrodes are placed on one side of a printed circuit board (PCB), and the mutual capacitance sensing circuit in the form an integrated circuit chip is mounted on the back side of the chip, with conventional PCB routing connecting the I/O contacts of the electrodes to the I/O contacts of the IC chip. The IC chip may for example be an ASIC. In another implementation, the electrodes are placed on one side of a printed circuit board (PCB) and the I/O contacts are coupled to the I/O contacts of a floating IC via a flex circuit with printed traces (sensing and driving lines). For example, the PCB containing the electrodes is connected to one end of a flex circuit and the sensor IC is attached to the other end of the flex circuit. Alternatively, the electrodes may be applied directly to the flexible member of the flex circuit. 
     Several touch devices  200 - 280  with nodes  202  set up in a non 2D array will now be described in conjunction with  FIGS. 8-15 . It should be appreciated that this are given by way of example and not by way of limitation as the invention can extend beyond these limited embodiments. 
     In most of these embodiments, the touch devices includes a plurality of nodes  202  that are positioned side by side along a predetermined path. This arrangement works particularly well for performing scrolling operations or parameter control operations. The path may be a closed loop path or an opened loop path. Furthermore, each of the nodes  202  include an electrode pair of drive electrode  204  and sense electrode  206 . Moreover, the number of drive lines  208  is equal to the number of sense lines  210 , and further the number of nodes  202  is the square of this number. It should be appreciated however that this is not a limitation. 
       FIG. 8  is a diagram of a circular touch device  200 . The circular touch device  200  is divided into several independent and spatially distinct nodes  202  that are positioned in a circular manner. Each of the nodes  202  represents a different angular position within the circular shape. Although not shown, the nodes may also be placed at radial locations from the center of the touch surface to the perimeter of the touch surface. 
       FIG. 9  is a diagram of a linear touch device  220 . The linear touch device  220  is divided into several independent and spatially distinct nodes  202  that are positioned next to one another along a straight line. Each of the nodes  202  represents a different linear position. Although shown vertical, it should be appreciated that the linear touch device may also be horizontal or at an angle. Moreover, although shown straight, in some cases it may be desirable to use a curved line such as one that is U shaped, S shaped, etc. 
       FIG. 10  is a diagram of another type of linear touch device  230 . The linear touch device  250  is divided into several independent and spatially distinct nodes  202  that are positioned in the form of a “+” shape. This embodiment includes both a horizontal line and a vertical line that cross each other. 
       FIG. 11  is a diagram of a combined touch device  240 . For example, it may combine two sets of scrolling/parameter control regions as for example the circular region described in  FIG. 9  and the plus region described in  FIG. 10 . 
       FIGS. 12-14  are diagrams of a touch devices  250 - 270  include a scrolling or parameter control set up  282  and one or more distinct buttons  284 . The scrolling or parameter control set up  282  include nodes  202  configured similarly to any of those previously described  200 - 240 . The buttons  284 , on the other hand, include additional node(s)  202 . Each button may include one or more nodes. The minimum required node is one, but in some cases it may be desirable to include multiple nodes. The buttons  284  may be positioned inside and/or outside the scrolling region  282 . They may be placed in close proximity of the scrolling region  282  as for example around the periphery of the scrolling region  282  ( FIGS. 12 and 13 ) and/or they may be placed away from the scrolling region  282  ( FIG. 14 ). 
       FIG. 15  is diagram of a touch device  280  that only includes a button arrangement having a plurality of buttons  284 . Each button  284  has a different task or function assigned thereto. The buttons  284  may be arranged in any manner within a user interface of an electronic device. 
       FIG. 16  is a diagram of a touch assembly  300 , in accordance with one embodiment of the present invention. The touch assembly  300  includes a plurality of mutual capacitive sensing nodes  302  coupled to a host controller  304  via flex circuit  306 . The nodes  302  may be disposed on the flexible member of the flex circuit  306  or alternatively on a printed circuit board that is attached to the flexible member of the flex circuit. The nodes  302  include a drive electrode  308  and a sense electrode  310  as described above. Although the nodes and electrodes can be arranged in accordance with any of the embodiments described above, in the illustrated embodiment the nodes and electrodes are set up similarly to  FIG. 8 . 
     The flexible member  307  of the flex circuit  306  includes a first neck  312 , a landing area  314  and a second neck  316 . The first neck  312  includes a plurality of traces  313  coupling the I/O contacts of the nodes  302  to corresponding I/O contacts of an input controller  318  disposed on the landing area  314  of the flex circuit  306 . The input controller  318  may for example include a capacitive sensing microprocessor. In order to reduce the number of traces and I/O contacts of the input controller, the drive and sense electrodes of the nodes may be configured to share the traces that couple back to the I/O contacts of the input controller. Furthermore, in order to allow sensing, each node may include a different arrangement of drive and sense trace coupled to their corresponding electrodes. In one embodiment, the number of traces and thus the number of I/O contacts is less than the number nodes  302 . In one implementation of this embodiment, the number of traces and thus the number of I/O contacts of the input controller is equal to the square root of the number of nodes  302 . This is in contrast to a self capacitive device where there is typically one trace for each electrode as well as one for ground. (e.g., in the case of a sixteen electrodes, there would be seventeen traces on the first neck  312 ). Additional traces may be provided for other input means as for example mechanical buttons, switches, etc. 
     The second neck  316  includes a plurality of traces  317  coupling the I/O contacts of the input controller  318  to corresponding I/O contacts of the host controller  304 . The number of lines typically depends on the communication protocol being used. By way of example, the second neck  316  may include six traces  317  for power and serial data (e.g., USB). In some cases, the flex circuit  306  is connected to the host controller  304  through a connector arrangement that utilizes pins or contacts (e.g., male/female). In this way, the touch sensing unit  302  and flex circuit  306  is a separate unit that can couple to and decouple from the host controller  304  thereby making assembly easier. In other cases, they are permanently attached thereby creating a single unit. The host controller  304  may be positioned on the flexible member of the flex circuit or alternatively on a printed circuit board such as the main board of the electronic device. 
       FIG. 17  is a block diagram of an exemplary electronic device  350 , in accordance with one embodiment of the present invention. The electronic device typically includes a processor  356  configured to execute instructions and to carry out operations associated with the electronic device  350 . For example, using instructions retrieved for example from memory, the processor  356  may control the reception and manipulation of input and output data between components of the electronic device  350 . The processor  356  can be implemented on a single-chip, multiple chips or multiple electrical components. For example, various architectures can be used for the processor  356 , including dedicated or embedded processor, single purpose processor, controller, ASIC, and so forth. 
     In most cases, the processor  356  together with an operating system operates to execute computer code and produce and use data. The operating system may correspond to well known operating systems such as OSX, DOS, Unix, Linux, and Palm OS, or alternatively to special purpose operating system, such as those used for limited purpose appliance-type devices (e.g., media players). The operating system, other computer code and data may reside within a memory block  358  that is operatively coupled to the processor  56 . Memory block  358  generally provides a place to store computer code and data that are used by the electronic device  350 . By way of example, the memory block  58  may include Read-Only Memory (ROM), Random-Access Memory (RAM), hard disk drive, flash memory and/or the like. 
     The electronic device  350  also includes a display  368  that is operatively coupled to the processor  356 . The display  368  is generally configured to display a graphical user interface (GUI) that provides an easy to use interface between a user of the electronic device  350  and the operating system or application running thereon. The display  368  may for example be a liquid crystal display (LCD). 
     The electronic device  350  also includes one or more touch sensing devices  380  that utilize the mutual capacitive sensing technology described herein. The one or more touch sensing devices are operatively coupled to the processor  356 . The touch sensing devices  380  are configured to transfer data from the outside world into the electronic device  350 . The touch sensing device  380  may for example be used to perform movements such as scrolling and to make selections with respect to the GUI on the display  368 . The touch sensing device  380  may also be used to issue commands in the electronic device  350 . The touch sensing devices may be selected from fixed and/or movable touch pads, touch screens and/or touch sensitive housings. 
     The touch sensing device  380  recognizes touches, as well as the position and magnitude of touches on a touch sensitive surface. The touch sensing device  380  reports the touches to the processor  356  and the processor  356  interprets the touches in accordance with its programming. For example, the processor  356  may initiate a task in accordance with a particular touch. Alternatively, a dedicated processor can be used to process touches locally at the touch sensing device and reduce demand for the main processor of the electronic device. 
     In one particular embodiment of the present invention, the electronic devices described above correspond to hand-held electronic devices with small form factors. As used herein, the term “hand held” means that the electronic device is typically operated while being held in a hand and thus the device is sized and dimension for such use. Examples of hand held devices include PDAs, Cellular Phones, Media players (e.g., music players, video players, game players), Cameras, GPS receivers, Remote Controls, and the like. 
     As should be appreciated, the touch sensing device can reduce the number of input devices needed to support the device and in many cases completely eliminate input devices other than the touch sensing devices. The device is therefore more aesthetically pleasing (e.g., planar smooth surfaces with limited to no breaks gaps or lines), and in many cases can be made smaller without sacrificing screen size and input functionality, which is very beneficial for hand held electronic device especially those hand held electronic device that are operated using one hand (some hand held electronic device require two handed operation while others do not). 
     The touch sensing devices of the present invention are a perfect fit for small form factor devices such as hand held devices, which have limited space available for input interfaces, and which require adaptable placement of input interfaces to permit operation while being carried around. This is especially true when you consider that the functionality of handheld devices have begun to merge into a single hand held device. At some point, there is not enough real estate on the device for housing all the necessary buttons and switches without decreasing the size of the display or increasing the size of the device, both of which leave a negative impression on the user. In fact, increasing the size of the device may lead to devices, which are no longer considered “hand-held.” 
     In one particular implementation, the hand held device is a music player and the touch sensing devices are configured to generate control signals associated with a music player. For example, the touch sensing device may include list scrolling functionality, volume control functionality and button functionality including, Select, Play/Pause, Next, Previous and Menu. 
       FIG. 18  is a perspective diagram of a media player  400 , in accordance with one embodiment of the present invention. The term “media player” generally refers to computing devices that are dedicated to processing media such as audio, video or other images, as for example, music players, game players, video players, video recorders, cameras and the like. These devices are generally portable so as to allow a user to listen to music, play games or video, record video or take pictures wherever the user travels. In one embodiment, the media player is a handheld device that is sized for placement into a pocket of the user. By being pocket sized, the user does not have to directly carry the device and therefore the device can be taken almost anywhere the user travels (e.g., the user is not limited by carrying a large, bulky and often heavy device, as in a portable computer). 
     Media players generally have connection capabilities that allow a user to upload and download data to and from a host device such as a general purpose computer (e.g., desktop computer, portable computer). For example, in the case of a camera, photo images may be downloaded to the general purpose computer for further processing (e.g., printing). With regards to music players, songs and play lists stored on the general purpose computer may be downloaded into the music player. In the illustrated embodiment, the media player  400  is a pocket sized hand held MP3 music player that allows a user to store a large collection of music. By way of example, the MP3 music player may correspond to any of those iPod music players manufactured by Apple Computer of Cupertino, Calif. (e.g., standard, mini, iShuffle, Nano, etc.). 
     As shown in  FIG. 18 , the media player  400  includes a housing  402  that encloses internally various electrical components (including integrated circuit chips and other circuitry) to provide computing operations for the media player  400 . The integrated circuit chips and other circuitry may include a microprocessor, memory (e.g., ROM, RAM), a power supply (e.g., battery), a circuit board, a hard drive, and various input/output (I/O) support circuitry. In the case of music players, the electrical components may include components for outputting music such as an amplifier and a digital signal processor (DSP). In the case of video recorders or cameras the electrical components may include components for capturing images such as image sensors (e.g., charge coupled device (CCD) or complimentary oxide semiconductor (CMOS)) or optics (e.g., lenses, splitters, filters). In addition to the above, the housing may also define the shape or form of the media player. That is, the contour of the housing  402  may embody the outward physical appearance of the media player  400 . 
     The media player  400  also includes a display screen  404 . The display screen  404  is used to display a graphical user interface as well as other information to the user (e.g., text, objects, graphics). By way of example, the display screen  404  may be a liquid crystal display (LCD). As shown, the display screen  404  is visible to a user of the media player  400  through an opening  405  in the housing  402 , and through a transparent wall  406  that is disposed in front of the opening  405 . Although transparent, the transparent wall  406  may be considered part of the housing  402  since it helps to define the shape or form of the media player  400 . 
     The media player  400  also includes a touch pad  410 . The touch pad  410  is configured to provide one or more control functions for controlling various applications associated with the media player  400 . For example, the touch initiated control function may be used to move an object or perform an action on the display screen  404  or to make selections or issue commands associated with operating the media player  400 . In most cases, the touch pad  410  is arranged to receive input from a finger moving across the surface of the touch pad  110  in order to implement the touch initiated control function. 
     The manner in which the touch pad  410  receives input may be widely varied. In one embodiment, the touch pad  410  is configured receive input from a linear finger motion. In another embodiment, the touch pad  410  is configured receive input from a rotary or swirling finger motion. In yet another embodiment, the touch pad  410  is configured receive input from a radial finger motion. Additionally or alternatively, the touch pad  410  may be arranged to receive input from a finger tapping on the touch pad  400 . By way of example, the tapping finger may initiate a control function for playing a song, opening a menu and the like. 
     In one embodiment, the control function corresponds to a scrolling feature. For example, in the case of an MP3 player, the moving finger may initiate a control function for scrolling through a song menu displayed on the display screen  404 . The term “scrolling” as used herein generally pertains to moving displayed data or images (e.g., text or graphics) across a viewing area on a display screen  404  so that a new set of data (e.g., line of text or graphics) is brought into view in the viewing area. In most cases, once the viewing area is full, each new set of data appears at the edge of the viewing area and all other sets of data move over one position. That is, the new set of data appears for each set of data that moves out of the viewing area. In essence, the scrolling function allows a user to view consecutive sets of data currently outside of the viewing area. The viewing area may be the entire viewing area of the display screen  104  or it may only be a portion of the display screen  404  (e.g., a window frame). 
     The direction of scrolling may be widely varied. For example, scrolling may be implemented vertically (up or down) or horizontally (left or right). In the case of vertical scrolling, when a user scrolls down, each new set of data appears at the bottom of the viewing area and all other sets of data move up one position. If the viewing area is full, the top set of data moves out of the viewing area. Similarly, when a user scrolls up, each new set of data appears at the top of the viewing area and all other sets of data move down one position. If the viewing area is full, the bottom set of data moves out of the viewing area. In one implementation, the scrolling feature may be used to move a Graphical User Interface (GUI) vertically (up and down), or horizontally (left and right) in order to bring more data into view on a display screen. By way of example, in the case of an MP3 player, the scrolling feature may be used to help browse through songs stored in the MP3 player. The direction that the finger moves may be arranged to control the direction of scrolling. For example, the touch pad may be arranged to move the GUI vertically up when the finger is moved in a first direction and vertically down when the finger is moved in a second direction 
     To elaborate, the display screen  404 , during operation, may display a list of media items (e.g., songs). A user of the media player  400  is able to linearly scroll through the list of media items by moving his or her finger across the touch pad  410 . As the finger moves around the touch pad  410 , the displayed items from the list of media items are varied such that the user is able to effectively scroll through the list of media items. However, since the list of media items can be rather lengthy, the invention provides the ability for the user to rapidly traverse (or scroll) through the list of media items. In effect, the user is able to accelerate their traversal of the list of media items by moving his or her finger at greater speeds. 
     In one embodiment, the media player  400  via the touch pad  410  is configured to transform a swirling or whirling motion of a finger into translational or linear motion, as in scrolling, on the display screen  404 . In this embodiment, the touch pad  410  is configured to determine the angular location, direction, speed and acceleration of the finger when the finger is moved across the top planar surface of the touch pad  410  in a rotating manner, and to transform this information into signals that initiate linear scrolling on the display screen  404 . In another embodiment, the media player  400  via the touch pad  410  is configured to transform radial motion of a finger into translational or linear motion, as in scrolling, on the display screen  404 . In this embodiment, the touch pad  410  is configured to determine the radial location, direction, speed and acceleration of the finger when the finger is moved across the top planar surface of the touch pad  410  in a radial manner, and to transform this information into signals that initiate linear scrolling on the display screen  404 . In another embodiment, the media player  400  via the touch pad  410  is configured to transform both angular and radial motion of a finger into translational or linear motion, as in scrolling, on the display screen  404 . 
     The touch pad generally consists of a touchable outer surface  411  for receiving a finger for manipulation on the touch pad  410 . Although not shown in  FIG. 20 , beneath the touchable outer surface  411  is a sensor arrangement. The sensor arrangement includes a plurality of sensors that are configured to activate as the finger performs an action over them. In the simplest case, an electrical signal is produced each time the finger passes a sensor. The number of signals in a given time frame may indicate location, direction, speed and acceleration of the finger on the touch pad, i.e., the more signals, the more the user moved his or her finger. In most cases, the signals are monitored by an electronic interface that converts the number, combination and frequency of the signals into location, direction, speed and acceleration information. This information may then be used by the media player  400  to perform the desired control function on the display screen  404 . By way of example, the sensor arrangement may correspond to any of those described herein. 
     The position of the touch pad  410  relative to the housing  402  may be widely varied. For example, the touch pad  410  may be placed at any external surface (e.g., top, side, front, or back) of the housing  402  that is accessible to a user during manipulation of the media player  400 . In most cases, the touch sensitive surface  411  of the touch pad  410  is completely exposed to the user. In the illustrated embodiment, the touch pad  410  is located in a lower, front area of the housing  402 . Furthermore, the touch pad  410  may be recessed below, level with, or extend above the surface of the housing  402 . In the illustrated embodiment, the touch sensitive surface  411  of the touch pad  410  is substantially flush with the external surface of the housing  402 . 
     The shape of the touch pad  410  may also be widely varied. For example, the touch pad  410  may be circular, rectangular, triangular, and the like. In general, the outer perimeter of the shaped touch pad defines the working boundary of the touch pad. In the illustrated embodiment, the touch pad  410  is circular. Circular touch pads allow a user to continuously swirl a finger in a free manner, i.e., the finger can be rotated through 360 degrees of rotation without stopping. Furthermore, the user can rotate his or her finger tangentially from all sides thus giving it more range of finger positions. For example, when the media player is being held, a left handed user may choose to use one portion of the touch pad  410  while a right handed user may choose to use another portion of the touch pad  410 . More particularly, the touch pad is annular, i.e., shaped like or forming a ring. When annular, the inner and outer perimeter of the shaped touch pad defines the working boundary of the touch pad. 
     In addition to above, the media player  400  may also include one or more buttons  412 . The buttons  412  are configured to provide one or more dedicated control functions for making selections or issuing commands associated with operating the media player  400 . By way of example, in the case of an MP3 music player, the button functions may be associated with opening a menu, playing a song, fast forwarding a song, seeking through a menu and the like. The button functions are implemented via a mechanical clicking action or alternatively via a sensor arrangement such as those described herein. The position of the buttons  412  relative to the touch pad  410  may be widely varied. For example, they may be adjacent one another or spaced apart. In the illustrated embodiment, the buttons  412  are separated from the touch pad  410  (see for example  FIG. 14 ). As shown, there are four buttons  412 A in a side by side relationship above the touch pad  410  and one button  412 B disposed in the center or middle of the touch pad  410 . By way of example, the plurality of buttons  412  may consist of a menu button, play/stop button, forward seek button and a reverse seek button, select button (enter) and the like. Alternatively or additionally, the buttons may be implemented with a movable touch pad. 
     Moreover, the media player  400  may also include a hold switch  414 , a headphone jack  416  and a data port  418 . The hold switch  414  is configured to turn the input devices of the media device  400  on and off. The headphone jack  416  is capable of receiving a headphone connector associated with headphones configured for listening to sound being outputted by the media device  400 . The data port  418  is capable of receiving a data connector/cable assembly configured for transmitting and receiving data to and from a host device such as a general purpose computer. By way of example, the data port  418  may be used to upload or down load songs to and from the media device  400 . The data port  418  may be widely varied. For example, the data port may be a PS/2 port, a serial port, a parallel port, a USB port, a Firewire port and the like. In some cases, the data port  118  may be a radio frequency (RF) link or optical infrared (IR) link to eliminate the need for a cable. Although not shown in  FIG. 20 , the media player  400  may also include a power port that receives a power connector/cable assembly configured for delivering powering to the media player  400 . In some cases, the data port  418  may serve as both a data and power port. 
     In any of the embodiments described or contemplated by this specification, the touch sensing devices may be configured to provide visual information to indicate when and where the touches occur, to invoke a touch (location where a user should touch), or as otherwise programmed. In the case of a touch screen, the visual information may be provided by the graphical display positioned behind the touch screen. In the case of the touch sensitive housing, or touch pad (or possibly with the touch screen), this may be accomplished with a visual feedback system that is capable of adjusting the visual stimuli of the touch surface. 
     The visual feedback system may include visual surface changing elements, which can be separate or integral with the sensing elements. In fact, the visual surface changing elements may be mapped to the sensor coordinates such that particular visual surface changing elements are tied to particular sensor coordinates. By way of example, the visual surface changing elements may be light devices such as light emitting diodes that illuminate the touch surface. For example, the light devices may be positioned in an array or matrix similarly to the sensing devices. Alternatively, the visual surface changing elements may be embodied as electronic inks or other color changing surfaces. 
     If used, this visual feedback feature allows the display of pop-up buttons, characters, and indicators around the touch surface, which can disappear when not in use or required, or glowing special effects that trace or outline a users fingers in contact with the touch surface, or otherwise provide visual feedback for the users of the device. In one implementation, the handheld device is configured to sense one or more touches and provide visual feedback in the area of the touches. In another implementation, the handheld device is configured to provide visual feedback on the touch surface, detect a touch in the area of the visual feedback, and to perform an action that is associated with the visual feedback. An example of such an arrangement can be found in U.S. patent application Ser. No. 11/394,493, which is herein incorporated by reference. 
     While this invention has been described in terms of several preferred embodiments, there are alterations, permutations, and equivalents, which fall within the scope of this invention. It should also be noted that there are many alternative ways of implementing the methods and apparatuses of the present invention. It is therefore intended that the following appended claims be interpreted as including all such alterations, permutations, and equivalents as fall within the true spirit and scope of the present invention.

Metadata:
Filing Date: 20060706
Publication Date: 20160607
Grant Date: 20160607
Priority Date: 20060706
Inventors: HOTELLING STEVE
Assignee: APPLE INC
CPC Classifications: [{"code": "H03K2217/96077", "inventive": false, "first": false, "tree": "[]"}, {"code": "H03K2217/960775", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/044", "inventive": true, "first": true, "tree": "[]"}, {"code": "H03K17/962", "inventive": true, "first": true, "tree": "[]"}, {"code": "H03K2217/960775", "inventive": false, "first": false, "tree": "[]"}, {"code": "H03K2217/96077", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/0443", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0443", "inventive": true, "first": false, "tree": "[]"}, {"code": "H03K17/962", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 38630417