Systems And Methods For Determining User Input Using Position Information And Force Sensing

Abstract

The embodiments described herein provide devices and methods that facilitate improved input device performance. Specifically, the devices and methods provide improved resistance to the effects of errors that may be caused by the motion of detected objects on such input devices, and in particular, to the effect of aliasing errors on input devices that use capacitive techniques to generate images of sensor values. The devices and methods provide improved resistance to the effects of aliasing errors by using force values indicative of force applied to the input surface. Specifically, the devices and methods use the force value to disambiguate determined position information for objects detected in the images of sensor values. This disambiguation of position information can lead to a reduction in the effects of aliasing errors and can thus improve the accuracy and usability of the input device.

Description

PRIORITY CLAIM

[0001] This application claims priority to U.S. Provisional Patent Application Ser. No. 61/619,344, filed Apr. 2, 2012

FIELD OF THE INVENTION

[0002] This invention generally relates to electronic devices, and more specifically relates to input devices.

BACKGROUND OF THE INVENTION

[0003] Input devices including proximity sensor devices (also commonly called touchpads or touch sensor devices) are widely used in a variety of electronic systems. A proximity sensor device typically includes a sensing region, often demarked by a surface, in which the proximity sensor device determines the presence, location and/or motion of one or more input objects. Proximity sensor devices may be used to provide interfaces for the electronic system. For example, proximity sensor devices are often used as input devices for larger computing systems (such as opaque touchpads integrated in, or peripheral to, notebook or desktop computers, or as transparent sensor devices integrated with display screens to provide a touch screen interface).

[0004] Many proximity sensor devices use capacitive techniques to sense input objects. Such proximity sensor devices may typically incorporate either profile capacitive sensors or capacitive image sensors. Capacitive profile sensors alternate between multiple axes (e.g., x and y), while capacitive image sensors scan multiple transmitter rows to produce a more detailed capacitive "image" of "pixels" associated with an input object. While capacitive image sensors are advantageous in a number of respects, they do share some potential disadvantages.

[0005] Specifically, because of the time required to generate each capacitive image, image sensors can be sensitive to errors caused by quickly moving objects. For example, aliasing errors may arise when sequential images show input objects at different locations. In such cases it can be difficult to determine if the detected input objects are the same input object or different input objects. Likewise, it can be difficult to determine where a detected object first entered or later exited the sensing region. These aliasing errors can occur when objects are quickly moving within or in and/or out of the sensing region. In such situations the proximity sensor device can incorrectly interpret the presence and movement of such objects. Such errors can thus result in unwanted or missed user interface actions, and thus can frustrate the user and degrade the usability of the device.

[0006] Thus, while capacitive image proximity sensor devices are advantageous in a number of respects, there is a continuing need to improve the performance of such devices. For example, to improve the responsiveness of such sensors, or to improve the sensor's resistance to errors, such as aliasing errors.

[0007] Other desirable features and characteristics will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.

BRIEF SUMMARY OF THE INVENTION

[0008] The embodiments of the present invention provide devices and methods that facilitate improved input device performance. Specifically, the devices and methods provide improved resistance to the effects of errors that may be caused by the motion of detected objects on such input devices, and in particular, to the effect of aliasing errors on input devices that use capacitive techniques to generate images of sensor values. The devices and methods provide improved resistance to the effects of aliasing errors by using force values indicative of force applied to the input surface. Specifically, the devices and methods use the force value to disambiguate determined position information for objects detected in the images of sensor values. This disambiguation of position information can lead to a reduction in the effects of aliasing errors and can thus improve the accuracy and usability of the input device.

[0009] In one embodiment, a processing system is provided for an input device having a plurality of sensor electrodes, where the processing system comprises a sensor module and a determination module. The sensor module comprises sensor circuitry configured to operate the plurality of sensor electrodes to generate images of sensor values indicative of objects in a sensing region proximate to an input surface at a first rate. The sensor module is further configured to operate at least one force sensor to generate force values indicative of force applied to the input surface at a second rate. The determination module is configured to determine if an input object detected in a first image of sensor values and an input object detected in a second image of sensor values remained in contact with the input surface between the first image and the second image based at least in part on the force values. Such a determination can disambiguate the positional information for the detected objects, and thus can be used to improve the accuracy and usability of the input device.

[0010] For example, such a determination can disambiguate whether such detected objects indicate a first object lifting from the input surface and a second object being placed on the input surface, or instead indicates the same input object being moved across the input surface without lifting from the input surface. Such a disambiguation of position information can lead improve the likelihood that the input device will respond to the detected objects correctly, and thus can improve the accuracy and usability of the input device.

[0011] In another embodiment, a processing system is provided for an input device having a plurality of sensor electrodes, where the processing system comprises a sensor module and a determination module. The sensor module comprises sensor circuitry configured to operate the plurality of sensor electrodes to generate images of sensor values indicative of objects in a sensing region proximate to an input surface at a first rate. The sensor module is further configured to operate at least one force sensor to generate force values indicative of force applied to the input surface at a second rate. The determination module is configured to determine an initial contact location for an input object first detected in a first image of sensor values based at least in part on at least one force value preceding the first image of sensor values and the first image of sensor values. Such a determination can disambiguate the positional information for the detected objects, and thus can be used to improve the accuracy and usability of the input device.

[0012] For example, such a determination can disambiguate whether such a detected object had an initial contact location in a specified region that would indicate a specific user interface action. Such a disambiguation of position information can lead improve the likelihood that the input device will respond to the detected object correctly, and thus can improve the accuracy and usability of the input device.

BRIEF DESCRIPTION OF DRAWINGS

[0013] The preferred exemplary embodiment of the present invention will hereinafter be described in conjunction with the appended drawings, where like designations denote like elements, and:

[0014] FIG. 1 is a block diagram of an exemplary system that includes an input device in accordance with an embodiment of the invention;

[0015] FIGS. 2A and 2B are block diagrams of sensor electrodes in accordance with exemplary embodiments of the invention;

[0016] FIGS. 3A-3B are top and side views an exemplary input device and that includes at least one force sensor;

[0017] FIGS. 4-7 are schematic views of an exemplary input device with one or more input objects in the sensing region; and

[0018] FIG. 8 is a schematic view of an input device showing various exemplary object positions.

DETAILED DESCRIPTION OF THE INVENTION

[0019] The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary, or the following detailed description.

[0020] Various embodiments of the present invention provide input devices and methods that facilitate improved usability. FIG. 1 is a block diagram of an exemplary input device 100, in accordance with embodiments of the invention. The input device 100 may be configured to provide input to an electronic system (not shown). As used in this document, the term "electronic system" (or "electronic device") broadly refers to any system capable of electronically processing information. Some non-limiting examples of electronic systems include personal computers of all sizes and shapes, such as desktop computers, laptop computers, netbook computers, tablets, web browsers, e-book readers, and personal digital assistants (PDAs). Additional example electronic systems include composite input devices, such as physical keyboards that include input device 100 and separate joysticks or key switches. Further example electronic systems include peripherals such as data input devices (including remote controls and mice), and data output devices (including display screens and printers). Other examples include remote terminals, kiosks, and video game machines (e.g., video game consoles, portable gaming devices, and the like). Other examples include communication devices (including cellular phones, such as smart phones), and media devices (including recorders, editors, and players such as televisions, set-top boxes, music players, digital photo frames, and digital cameras). Additionally, the electronic system could be a host or a slave to the input device.

[0021] The input device 100 can be implemented as a physical part of the electronic system, or can be physically separate from the electronic system. As appropriate, the input device 100 may communicate with parts of the electronic system using any one or more of the following: buses, networks, and other wired or wireless interconnections. Examples include I.sup.2C, SPI, PS/2, Universal Serial Bus (USB), Bluetooth, RF, SMBus, and IRDA.

[0022] In FIG. 1, the input device 100 is shown as a proximity sensor device (also often referred to as a "touchpad" or a "touch sensor device") configured to sense input provided by one or more input objects 140 in a sensing region 120. Example input objects include fingers and styli, as shown in FIG. 1.

[0023] Sensing region 120 encompasses any space above, around, in and/or near the input device 100 in which the input device 100 is able to detect user input (e.g., user input provided by one or more input objects 140). The sizes, shapes, and locations of particular sensing regions may vary widely from embodiment to embodiment. In some embodiments, the sensing region 120 extends from a surface of the input device 100 in one or more directions into space until signal-to-noise ratios prevent sufficiently accurate object detection. The distance to which this sensing region 120 extends in a particular direction, in various embodiments, may be on the order of less than a millimeter, millimeters, centimeters, or more, and may vary significantly with the type of sensing technology used and the accuracy desired. Thus, some embodiments sense input that comprises no contact with any surfaces of the input device 100, contact with an input surface (e.g. a touch surface) of the input device 100, contact with an input surface of the input device 100 coupled with some amount of applied force or pressure, and/or a combination thereof. In various embodiments, input surfaces may be provided by surfaces of casings within which sensor electrodes reside, by face sheets applied over the sensor electrodes or any casings, etc. In some embodiments, the sensing region 120 has a rectangular shape when projected onto an input surface of the input device 100.

[0024] The input device 100 also includes one or more force sensors that are coupled to a surface below the sensing region 120 and the processing system 110, and configured to provide force values that are indicative of force applied to the input surface (not shown in FIG. 1). The input device 100 utilizes capacitive sensing to detect user input in the sensing region 120. To facilitate capacitive sensing, the input device 100 comprises one or more sensing electrodes for detecting user input (not shown in FIG. 1).

[0025] Some implementations are configured to provide images that span one, two, three, or higher dimensional spaces. Some implementations are configured to provide projections of input along particular axes or planes.

[0026] In some capacitive implementations of the input device 100, voltage or current is applied to create an electric field. Nearby input objects cause changes in the electric field, and produce detectable changes in capacitive coupling that may be detected as changes in voltage, current, or the like.

[0027] Some capacitive implementations utilize arrays or other regular or irregular patterns of capacitive sensing elements to create electric fields. In some capacitive implementations, separate sensing elements may be ohmically shorted together to form larger sensor electrodes. Some capacitive implementations utilize resistive sheets, which may be uniformly resistive.

[0028] Some capacitive implementations utilize "transcapacitive" sensing methods. Transcapacitive sensing methods, sometimes referred to as "mutual capacitance", are based on changes in the capacitive coupling between sensor electrodes. In various embodiments, an input object near the sensor electrodes alters the electric field between the sensor electrodes, thus changing the measured capacitive coupling. In one implementation, a transcapacitive sensing method operates by detecting the capacitive coupling between one or more transmitter sensor electrodes (also "transmitter electrodes" or "transmitters") and one or more receiver sensor electrodes (also "receiver electrodes" or "receivers"). Transmitter sensor electrodes may be modulated relative to a reference voltage (e.g., system ground) to transmit transmitter signals. Receiver sensor electrodes may be held substantially constant relative to the reference voltage to facilitate receipt of resulting signals. A resulting signal may comprise effect(s) corresponding to one or more transmitter signals, one or more conductive input objects, and/or to one or more sources of environmental interference (e.g. other electromagnetic signals). Sensor electrodes may be dedicated transmitters or receivers, or may be configured to both transmit and receive.

[0029] In contrast, absolute capacitance sensing methods, sometimes referred to as "self capacitance", are based on changes in the capacitive coupling between sensor electrodes and an input object. In various embodiments, an input object near the sensor electrodes alters the electric field near the sensor electrodes, thus changing the measured capacitive coupling. In one implementation, an absolute capacitance sensing method operates by modulating sensor electrodes with respect to a reference voltage (e.g. system ground) to generate resulting signals on the sensor electrodes. In this case, the resulting signals received on a sensor electrode are generated by the modulation of that same sensor electrode. The resulting signals for absolute capacitive sensing thus comprise the effects of modulating the same sensor electrode, the effects of proximate conductive input objects, and the effects of and/or to one or more sources of environmental interference. Thus, by analyzing the resulting signals on the sensor electrodes the capacitive coupling between the sensor electrodes and input objects may be detected.

[0030] Notably, in transcapacitive sensing the resulting signals corresponding to each transmission of a transmitter signal are received on different sensor electrodes than the transmitter electrode used to transmit. In contrast, in absolute capacitive sensing each resulting signal is received on the same electrode that was modulated to generate that resulting signal.

[0031] In FIG. 1, processing system 110 is shown as part of the input device 100. The processing system 110 is configured to operate the hardware of the input device 100 to detect input in the sensing region 120. The processing system 110 comprises parts of or all of one or more integrated circuits (ICs) and/or other circuitry components. For example, as described above, the processing system 110 may include the circuit components for operating the plurality of sensor electrodes to generate images of sensor values indicative of objects in a sensing region proximate to an input surface, and may also include circuit components to operate at least one force sensor to generate force values indicative of force applied to an input surface.

[0032] In some embodiments, the processing system 110 also comprises electronically-readable instructions, such as firmware code, software code, and/or the like. In some embodiments, components composing the processing system 110 are located together, such as near sensing element(s) of the input device 100. In other embodiments, components of processing system 110 are physically separate with one or more components close to sensing element(s) of input device 100, and one or more components elsewhere. For example, the input device 100 may be a peripheral coupled to a desktop computer, and the processing system 110 may comprise software configured to run on a central processing unit of the desktop computer and one or more ICs (perhaps with associated firmware) separate from the central processing unit. As another example, the input device 100 may be physically integrated in a phone, and the processing system 110 may comprise circuits and firmware that are part of a main processor of the phone. In some embodiments, the processing system 110 is dedicated to implementing the input device 100. In other embodiments, the processing system 110 also performs other functions, such as operating display screens, driving haptic actuators, etc.

[0033] The processing system 110 may be implemented as a set of modules that handle different functions of the processing system 110. Each module may comprise circuitry that is a part of the processing system 110, firmware, software, or a combination thereof. In various embodiments, different combinations of modules may be used. Example modules include hardware operation modules for operating hardware such as sensor electrodes and display screens, data processing modules for processing data such as sensor signals and positional information, and reporting modules for reporting information. Further example modules include sensor operation modules configured to operate sensing element(s) and a determination module. In accordance with the embodiments described herein, the sensor module may be configured to operate the plurality of sensor electrodes to generate images of sensor values indicative of objects in a sensing region proximate to an input surface at a first rate. The sensor module may be further configured to operate at least one force sensor to generate force values indicative of force applied to the input surface at a second rate. In one embodiment, the determination module is configured to determine if an input object detected in a first image of sensor values and an input object detected in a second image of sensor values remained in contact with the input surface between the first image and the second image based at least in part on the force values. In another embodiment, the determination module may be configured to determine an initial contact location for an input object first detected in a first image of sensor values based at least in part on at least one force value preceding the first image of sensor values and the first image of sensor values. In either case such a determination can disambiguate the positional information for the detected objects, and thus can be used to improve the accuracy and usability of the input device.

[0034] In some embodiments, the processing system 110 responds to user input (or lack of user input) in the sensing region 120 directly by causing one or more actions. Example actions include changing operation modes, as well as GUI actions such as cursor movement, selection, menu navigation, and other functions. In some embodiments, the processing system 110 provides information about the input (or lack of input) to some part of the electronic system (e.g. to a central processing system of the electronic system that is separate from the processing system 110, if such a separate central processing system exists). In some embodiments, some part of the electronic system processes information received from the processing system 110 to act on user input, such as to facilitate a full range of actions, including mode changing actions and GUI actions.

[0035] For example, in some embodiments, the processing system 110 operates the sensing element(s) of the input device 100 to produce electrical signals indicative of input (or lack of input) in the sensing region 120. The processing system 110 may perform any appropriate amount of processing on the electrical signals in producing the information provided to the electronic system. For example, the processing system 110 may digitize analog electrical signals obtained from the sensor electrodes. As another example, the processing system 110 may perform filtering or other signal conditioning. As yet another example, the processing system 110 may subtract or otherwise account for a baseline, such that the information reflects a difference between the electrical signals and the baseline. As yet further examples, the processing system 110 may determine positional information, recognize inputs as commands, recognize handwriting, and the like. In one embodiment, processing system 110 includes a determination module configured to determine positional information for an input device based on the measurement.

[0036] "Positional information" as used herein broadly encompasses absolute position, relative position, velocity, acceleration, and other types of spatial information. Exemplary "zero-dimensional" positional information includes near/far or contact/no contact information. Exemplary "one-dimensional" positional information includes positions along an axis. Exemplary "two-dimensional" positional information includes motions in a plane. Exemplary "three-dimensional" positional information includes instantaneous or average velocities in space. Further examples include other representations of spatial information. Historical data regarding one or more types of positional information may also be determined and/or stored, including, for example, historical data that tracks position, motion, or instantaneous velocity over time.

[0037] Likewise, the term "force values" as used herein is intended to broadly encompass force information regardless of format. For example, the force values can be provided for each object as a vector or scalar quantity. As other examples, the force information can also include time history components used for gesture recognition. As will be described in greater detail below, the force values from the processing systems may be used to disambiguate positional information for detected objects, and thus can be used to improve the accuracy and usability of the input device.

[0038] In some embodiments, the input device 100 is implemented with additional input components that are operated by the processing system 110 or by some other processing system. These additional input components may provide redundant functionality for input in the sensing region 120, or some other functionality. FIG. 1 shows buttons 130 near the sensing region 120 that can be used to facilitate selection of items using the input device 100. Other types of additional input components include sliders, balls, wheels, switches, and the like. Conversely, in some embodiments, the input device 100 may be implemented with no other input components.

[0039] In some embodiments, the input device 100 comprises a touch screen interface, and the sensing region 120 overlaps at least part of an active area of a display screen. For example, the input device 100 may comprise substantially transparent sensor electrodes overlaying the display screen and provide a touch screen interface for the associated electronic system. The display screen may be any type of dynamic display capable of displaying a visual interface to a user, and may include any type of light emitting diode (LED), organic LED (OLED), cathode ray tube (CRT), liquid crystal display (LCD), plasma, electroluminescence (EL), or other display technology. The input device 100 and the display screen may share physical elements. For example, some embodiments may utilize some of the same electrical components for displaying and sensing. As another example, the display screen may be operated in part or in total by the processing system 110.

[0040] It should be understood that while many embodiments of the invention are described in the context of a fully functioning apparatus, the mechanisms of the present invention are capable of being distributed as a program product (e.g., software) in a variety of forms. For example, the mechanisms of the present invention may be implemented and distributed as a software program on information bearing media that are readable by electronic processors (e.g., non-transitory computer-readable and/or recordable/writable information bearing media readable by the processing system 110). Additionally, the embodiments of the present invention apply equally regardless of the particular type of medium used to carry out the distribution. Examples of non-transitory, electronically readable media include various discs, memory sticks, memory cards, memory modules, and the like. Electronically readable media may be based on flash, optical, magnetic, holographic, or any other storage technology.

[0041] In accordance with various embodiments of the invention, the input device 100 is configured with the processing system 110 coupled to a plurality of capacitive sensor electrodes and at least one force sensor.

[0042] In general, the input device 100 facilitates improved performance. Specifically, The input device 100 provides resistance to the effects of errors that may be caused by the motion of detected objects, and in particular, to the effect of aliasing errors that can be caused by the capacitive techniques to generate images of sensor values. The input device 100 provides improved resistance to the effects of aliasing errors by using force values indicative of force applied to the input surface. Specifically, the processing system 110 uses force values to disambiguate determined position information for objects detected in the images of sensor values.

[0043] In one embodiment, a processing system 110 is coupled to plurality of sensor electrodes and at least one force sensor. In one embodiment, the processing system 110 comprises a sensor module and a determination module. The processing system 110 is configured to operate the plurality of sensor electrodes to generate images of sensor values indicative of objects in a sensing region proximate to an input surface at a first rate. The processing system 110 is further configured to operate at least one force sensor to generate force values indicative of force applied to the input surface at a second rate. In one embodiment, the second rate is greater than the first rate, and specifically the second rate may be more than twice the first rate. In one embodiment, the processing system 110 is configured to determine if an input object detected in a first image of sensor values and an input object detected in a second image of sensor values remained in contact with the input surface between the first image and the second image based at least in part on the force values. In another embodiment, the processing system 110 is configured to determine an initial contact location for an input object first detected in a first image of sensor values based at least in part on at least one force value preceding the first image of sensor values and the first image of sensor values.

[0044] In either case such a determination can disambiguate the positional information for the detected objects, and thus can be used to improve the accuracy and usability of the input device 100.

[0045] As was described above, the processing system 110 is coupled to sensor electrodes to determine user input. Specifically, the processing system operates by detecting the capacitive coupling between one or more transmitter sensor electrodes and one or more receiver sensor electrodes. Turning now to FIG. 2, these figures conceptually illustrate exemplary sets of capacitive sensor electrodes configured to sense in a sensing region. Specifically, FIG. 2A shows electrodes 200 in a rectilinear arrangement, while FIG. 2B shows electrodes 225 in a radial/concentric arrangement. However, it will be appreciated that the invention is not so limited, and that a variety of electrode shapes and arrangements may be suitable in any particular embodiment.

[0046] Turning now to FIG. 2A, in the illustrated embodiment the capacitive sensor electrodes 200 comprise first sensor electrodes 210 and second sensor electrodes 220. Specifically, in the illustrated embodiment, the first sensor electrodes 210 comprise six electrodes 210-1 to 210-6, and the second sensor electrodes 220 comprise six electrodes 220-1 to 220-6. Each of the first sensor electrodes 210 is arranged to extend along a second axis. Specifically, each first sensor electrode 210 has a major axis that extends along the second axis. It should also be noted that the first sensor electrodes 210 are distributed in an array, with each of the first sensor electrodes 210 positioned a distance from adjacent first sensor electrodes 210 and corresponding to a different position in the first axis.

[0047] Likewise, each of the second sensor electrodes 220 is arranged to extend along a first axis, where the first and second axes are different axis. Specifically, each second sensor electrode 220 has a major axis that extends along the first axis. It should also be noted that the second sensor electrodes 220 are distributed in an array, with each of the second sensor electrodes 220 positioned a distance from adjacent second sensor electrodes 220 and corresponding to a different position in the second axis.

[0048] Sensor electrodes 210 and 220 are typically ohmically isolated from each other. That is, one or more insulators separate sensor electrodes 210 and 220 and prevent them from electrically shorting to each other. In some embodiments, sensor electrodes 210 and 220 are separated by insulative material disposed between them at cross-over areas; in such constructions, the sensor electrodes 210 and/or sensor electrodes 220 may be formed with jumpers connecting different portions of the same electrode. In some embodiments, sensor electrodes 210 and 220 are separated by one or more layers of insulative material. In some other embodiments, sensor electrodes 210 and 220 are separated by one or more substrates; for example, they may be disposed on opposite sides of the same substrate, or on different substrates that are laminated together. The capacitive coupling between the transmitter electrodes and receiver electrodes change with the proximity and motion of input objects in the sensing region associated with the transmitter electrodes and receiver electrodes.

[0049] In transcapacitive sensing, the sensor pattern is "scanned" to determine the capacitive couplings between transmitter and receiver electrodes. That is, the transmitter electrodes are driven to transmit transmitter signals and the receiver electrodes are used acquire the resulting signals. The resulting signals are then used to determine measurements of the capacitive couplings between electrodes, where each capacitive coupling between a transmitter electrode and a receiver electrode provides one "capacitive pixel". A two-dimensional array of measured values derived from the capacitive pixels form a "capacitive image" (also commonly referred to as a "capacitive frame") representative of the capacitive couplings at the pixels. Multiple capacitive images may be acquired over multiple time periods, and differences between them used to derive information about input in the sensing region. For example, successive capacitive images acquired over successive periods of time can be used to track the motion(s) of one or more input objects entering, exiting, and within the sensing region.

[0050] A detailed example of generating images of sensor values will now be given with reference to FIG. 2A. In this detailed example sensor values are generated on a "column-by-column", with the first resulting signals for each column captured substantially simultaneously. Specifically, each column of resulting signals is captured at a different time, and taken together are used to generate the first image of sensor values. In the embodiment of FIG. 2A, a transmitter signal may be transmitted with electrode 210-1, and first resulting signals captured with each of the receiver electrodes 220-1 to 220-6, where each first resulting signal comprises effects of the first transmitter signal. These six first resulting signals comprise a set (corresponding to a column) of first resulting signals that may be used to generate the first image of sensor values. Specifically, from each of these six first resulting signals provides a capacitive measurement that corresponds to a pixel in the first capacitive image, and together the six pixels make up a column in the first capacitive image.

[0051] Another transmitter signal may then be transmitted with electrode 210-2, and again first resulting signals may then be captured with each of the receiver electrodes 220-1 to 220-6. This comprises another column of first resulting signals that may be used to generate the first image. This process may be continued, transmitting from electrodes 210-3, 210-4, 210-5 and 210-6, with each transmission generating another column of first resulting signals until the complete first image of sensor values is generated.

[0052] It should next be noted that this is only one example of how such a capacitive image of sensor values can be generated. For example, such images could instead be generated on a "row-by row" basis using electrodes 220 as transmitter electrodes and electrodes 210 as receiver electrodes. In any case the images of sensor values can be generated and used to determine positional information for objects in the sensing region.

[0053] Next should be noted that in some embodiments the sensor electrodes 210 and 220 are both configured to be selectively operated as receiver electrodes and transmitter electrodes, and may also be selectively operated for absolute capacitive sensing. Thus, the sensor electrodes 210 may be operated as transmitter electrodes while the sensor electrodes 220 are operated as receiver electrodes to generate the image of sensor values. Likewise, the sensor electrodes 220 may be operated as transmitter electrodes while the sensor electrodes 210 are operated as receiver electrodes to generate images to generate the image sensor values. Finally, sensor electrodes 210 and 220 may be selectively modulated for absolute capacitive sensing.

[0054] It should next be noted again that while the embodiment illustrated in FIG. 2A shows sensor electrodes arranged in a rectilinear grid, that is this is just one example arrangement of the electrodes. In another example, the electrodes may be arranged to facilitate position information determination in polar coordinates (e.g., r, .THETA.). Turning now to FIG. 2B, capacitive sensor electrodes 225 in a radial/concentric arrangement are illustrated. Such electrodes are examples of the type that can be used to determine position information in polar coordinates.

[0055] In the illustrated embodiment, the first sensor electrodes 230 comprise 12 electrodes 230-1 to 230-12 that are arranged radially, with each of the first sensor electrodes 230 starting near a center point and extending in different radial directions outward. In the illustrated embodiment the second sensor electrodes 240 comprise four electrodes 240-1 to 240-4 that are arranged in concentric circles arranged around the same center point, with each second sensor electrode 240 spaced at different radial distances from the center point. So configured, the first sensor electrodes 230 and second sensor electrodes 240 can be used to generate images of sensor values.

[0056] As described above, generating image of sensor values is relatively processing intensive. For example, using transcapacitive sensing to scan the capacitive couplings either on a "row-by-row" or "column-by-column" basis generally requires significant time and processing capability because each row and/or column in the image is generated separately. Furthermore, the rate at which each row or column can be scanned may be further limited by the relatively large RC time constants in some input device sensor electrodes. Furthermore, in typical applications multiple capacitive images are acquired over multiple time periods, and differences between them used to derive information about input in the sensing region. For all these reasons, the rate at which images of sensor values can be generated may be limited.

[0057] As was described above, because of the time required to generate each capacitive image, image sensors can be sensitive to errors caused by quickly moving objects. For example, aliasing errors may arise when sequential images show input objects at different locations. In such cases it can be difficult to determine if the detected input objects are the same input object or different input objects. Likewise, it can be difficult to determine where a detected object first entered or later exited the sensing region.

[0058] Returning to FIG. 1, as was noted above the processing system 110 is further configured to operate at least one force sensor to generate force values that are indicative of force applied to an input surface. In general, the one or more force sensors are coupled to a surface and are configured to provide a plurality a measures of force applied to the surface. Such force sensor(s) can be implemented in a variety of different arrangements. To give several examples, the force sensor(s) can be implemented as multiple force sensors arranged near a perimeter of the sensing region 120. Furthermore, each of the force sensors can be implemented to measure compression force, expansion force, or both, as it is applied at the surface. Finally, a variety of different technologies can be used to implement the force sensors. For example, the force sensors can be implemented with variety of different technologies, including piezeoelectric force sensors, capacitive force sensors, and resistive force sensors.

[0059] In general, the force sensor(s) operate to provide signals to the processing system 110 that are indicative of force. The processing system 110 may be configured to perform a variety of actions to facilitate such force sensing. For example, the processing system 110 may perform a variety of processes on the signals received from the sensor(s). For example, processing system 110 may select or couple individual force sensor electrodes, calibrate individual force sensors, and determine force measurements from data provided by the force sensors.

[0060] Turning now to FIGS. 3A and 3B, examples of input objects in a sensing region and applying force to a surface are illustrated. Specifically, FIGS. 3A and 3B show top and side views of an exemplary input device 300. In the illustrated example, user's finger 302 and provides input to the device 300. Specifically, the input device 300 is configured to determine the position of the finger 302 and other input objects within the sensing region 306 using a sensor. For example, using a plurality of electrodes (e.g., electrodes 210 and 220 of FIG. 2A) configured to capacitively detect objects such as the finger 302, and a processor configured to determine the position of the fingers from the capacitive detection.

[0061] In accordance with the embodiments of the invention, the input device 300 is further configured include one or more force sensor(s) 310. Specifically, one or more force sensor(s) 310 are arranged about the sensing region 306. Each of these force sensor(s) provides a measure of the force applied to the surface 308 by the fingers. Each of these individual force sensors can be implemented with any suitable force sensing technology. For example, the force sensors can be implemented with piezeoelectric force sensors, capacitive force sensors, and/or resistive force sensors. It should be noted that while the force sensor(s) 310 are illustrated as being arranged around the perimeter of the sensing region 306 that this is just one example configuration. As one example, in other embodiments a full array of force sensors 310 could be provided to generate an "image" of force values.

[0062] The force sensor(s) are configured to each provide a measure of the force applied to the surface. A variety of different implementations can be used to facilitate this measurement. For example, the sensing element of the force sensor can be directly affixed to the surface. For example, the sensing element can be directly affixed to the underside of the surface or other layer. In such an embodiment, each force sensor can provide a measure of the force that is being applied to the surface by virtue of being directly coupled to the surface. In other embodiments, the force sensor can be indirectly coupled to the surface. For example, through intermediate coupling structures that transfer force, intermediate material layers or both. In any such case, the force sensors are again configured to each provide a measure of the force applied to the surface. In yet other embodiments the force sensors can be configured to directly detect force applied by the input object itself, or to a substrate directly above the force sensors.

[0063] In one specific example, the force sensor(s) can be implemented as contact--no contact sensors by being configured to simply indicate when contact is detected. Such a contact--no contact sensor can be implemented with a force sensor that identifies contact when detected force is above a specified threshold, and provides a simply binary output indicating that such contact has been detected. Variations in such contact--no contact sensors include the use of hysteresis in the force thresholds used determine contact. Additionally, such sensors can use averaging of detected force in determining if contact is occurring.

[0064] In general it will be desirable to position each of the plurality of force sensors near the perimeter edge of the sensor and to space the sensors to the greatest extent possible, as this will tend to maximize the accuracy of the sensing measurements. In most cases this will position the sensors near the outer edge of the sensing region. In other cases it will be near the outer edge of the touch surface, while the sensing region may extend beyond the surface for some distance. Finally, in other embodiments one or more the sensors can be positioned in the interior of the sensor.

[0065] In the example of FIG. 3, four force sensors 310 are positioned near the perimeter of the rectangular sensing region 306 and beneath the surface 308. However, it should be noted that this is just one example configuration. This, in other embodiments fewer or more of such sensors may be used. Furthermore, the sensors may be located in a variety of different positions beneath the surface 308. Thus, it is not necessary to locate the force sensors near the corners or perimeters of the surface 308.

[0066] It should be noted that many force sensors can be used to generate force values at relatively high rates compared to the rates at which images of sensor values can be generated. For example, in capacitive force sensors each force sensor can generate a forced value with relatively few capacitive measurements compared to the number of capacitive measurements required for each image, and thus force values can be generated at a relatively higher rate compared to rate at which images of sensor values can be generated. As will be described in greater detail below, the faster rate at which force values can be generated may be used to reduce errors in the positional information determined by the sensor. Specifically, the embodiments described herein can use the faster rate of force values to provide improved resistance to the effects of errors that may be caused by the motion of detected objects, and in particular, to the effect of aliasing errors. In such embodiments the faster rate of force values are used disambiguate determined position information for objects detected in the images of sensor values. This disambiguation of position information can lead to a reduction in the effects of aliasing errors and can thus improve the accuracy and usability of the input device. Furthermore, in other embodiments the force sensors can be provided to generate force values at the same rate at which capacitive images are generated. In these embodiments it will be generally desirable to control the force sensors such that the force values are generated between images such that the force values provide information regarding the contact of input objects between such images.

[0067] So configured, the at least one force sensors operate to generate force values that are indicative of force applied to the surface 308. As will now be described in detail, in the various embodiments the processing system is configured to determine if an input object detected in a first image of sensor values and an input object detected in a second image of sensor values remained in contact with the input surface between the first image and the second image based at least in part on these force values. In various other embodiments the processing system is configured to determine an initial contact location for an input object first detected in a first image of sensor values based at least in part on at least one force value preceding the first image of sensor values and the first image of sensor values. It should be noted that in determining an initial contact location calculating the actual location of initial contact is not required. Instead, in many cases all that is needed to determine an initial contact location is to determine if the initial contact was within a certain region or within a threshold distance of some location. Such an example will be described in greater detail below.

[0068] Turning now to FIGS. 4 and 5, the input device 300 is illustrated with two different exemplary input object scenarios. In FIG. 4, an input object (i.e., a finger 402) is illustrated moving across the sensing region 306 from a first position to a second position while remaining in contact with the surface 308. In FIG. 5, two input objects (i.e., finger 502 and finger 504) are shown, where finger 502 is being lifted from the surface 308 at the first position and shortly thereafter the finger 504 is placed at the surface in the second position.

[0069] It should be appreciated that when either scenario occurs within a sufficiently short time period, the input device 300 will effectively detect an image with a finger in the first position followed by an image with a finger in the second position. Without more information, the input device 300 may not be able to distinguish between the scenario illustrated in FIG. 4 where the finger stayed in contact with the surface 308 and the scenario illustrated in FIG. 5 where a finger was lifted from the surface 308 and thereafter a finger was quickly placed down on the surface 308. Without such a reliable determination, the input device 300 will be unable to reliably generate the appropriate response.

[0070] This can lead to several different potential problems. For example, the input device may not reliably "scroll" or "pan" as intended by the user in response to a motion across the surface. Instead, the motion across the surface by the finger may be interpreted as a new "tap" at the new location of the finger and inadvertently activate a function associated with such a tap. As another example, pointing with an input object can be misinterpreted as taps at a new location and vice versa. In such cases misinterpreting an intended "tap" as pointing motion can cause unwanted cursor jumping when selection was instead intended by the user.

[0071] The embodiments described herein avoid these potential problems by providing a mechanism for more reliably determining if an input object detected in a first image of sensor values and an input object detected in a second image of sensor values remained in contact with the input surface between the first image and the second image. Specifically, by using the force values from one or more force sensors to disambiguate whether the input object remained in contact between the images. Thus, the input device 300 may be then configured to generate a first user interface action in response to a determination that the input object detected in the second image of sensor values remained in contact with the input surface between the first image and the second image and generate a second user interface action in response to a determination that the input object detected in the second image of sensor values did not remain in contact with the input surface between the first image and the second image.

[0072] As was noted above, many types of force sensors can be utilized to provide force values to the processing system. By providing at least one force value between images generated by the sensor electrodes it can be more reliably determined whether the input object detected in a first image remained in contact with the surface between images. Specifically, if applied force is detected between the consecutive images it can be more reliably assumed that the input object remained in contact between images and thus the correct user interface response can be more reliably generated.

[0073] Furthermore, as was discussed above many typical force sensors can be configured to provide force values at a relatively high rate. Specifically, because of the amount of time and processing typically required to generate a full capacitive image (that will include numerous rows or columns of values, each generated at a different time) the rate at which such images may be generated is limited. In contrast, many force sensors can generate force values at considerably greater rate. This is particularly true of some capacitive force sensors, where each capacitive measurement may be used to generate a force value. Thus, by using such force sensors multiple force values can be generated between each generated image. Generating and using multiple force values between images can thus provide further ability to determine if an object has remained in contact with the surface between images, or if instead the object has lifted from the surface and the same or other object placed back down.

[0074] It should be noted that this is just one example of the type of ambiguity that can be potentially resolved through the use of force values. In another example such force values can be used to determine if an input object detected in a first image had actually initially contacted the input surface at a different location before it was first sensed in an image. Turning now to FIGS. 6 and 7, the input device 300 is illustrated with two such different exemplary input object scenarios. In FIG. 6, an input object (i.e., a finger 602) is illustrated with an initial detected location at a position 604 and then moving across the sensing region 306 to the second position 606. In FIG. 7, an input object (i.e., a finger 602) is illustrated with an initial contact location at a contact position 608 and then moving across the sensing region 306 from the position 604 to the second position 606. In both scenarios the input object is first detected in an image at position 604 and then subsequently detected in the next image at the second position 606. However, the two scenarios differ as to where the actual initial contact occurred.

[0075] Such a distinction can make a difference in applications where the resulting user interface action is dependent upon the location of initial contact by the input object. And without more information, the input device 300 may not be able to determine that the input object actually made initial contact at an earlier location than it was first detected in an image. Without such a reliable determination, the input device 300 will be unable to reliably generate the appropriate response.

[0076] This can lead to several different potential problems. For example, where a resulting user interface action is dependent upon the location of initial contact by the input object. As a specific example, in some cases a user interface may be configured to provide a pull-down interface in response to a user initially contacting the sensor near an edge region and dragging the input object across the sensing region 306. Such pull-down interfaces can provide a variety of functions to the user. However, in most embodiments such pull-down interfaces will only be activated when the initial contact location is determined be at or near an edge region of the sensing region. Thus, if the initial contact location is inaccurately determined to not be near the edge the pull-down interface will not be activated. As noted above, with a quickly moving finger the input object may not be detected in an image at its first true contact location (e.g., contact location 608) and may instead only be detected at a later position (e.g., position 604). In such a scenario the pull-down interface may incorrectly not be activated when it was intended to be activated by the user.

[0077] It should be noted that in such embodiments it may be sufficient to determine that a contact prior to detecting the input object in the first image did not occur prior to the object being detected in an image, or did not occur within a specified threshold distance prior to the object being detected in the image. Stated another way, the lack of force detection can be used to help make the disambiguation even if the initial contact location was within an edge region. For example, in the scenario of FIG. 6 if no contact above a threshold level is detected in the immediate time prior to having detected the image at position 604 then it can be reliably determined that contact in the edge region did not occur and an edge region specific response need not be generated.

[0078] As another example, in some embodiments a gesture may be performed when an initial contact location is within a distance threshold or some other criteria such as speed of motion. In this case the embodiments described herein can be used to determine if such an initial contact within a threshold occurred. Again, the input device can be configured to not perform the gesture when an initial contact is not detected immediately prior the input object being detected in an image, and where the input object was detected outside the specified distance threshold in that image. Alternatively, the input device can be configured perform the gesture only when the initial contact is affirmatively determined to be within the specified distance threshold. For example, when an initial contact is determined to have occurred prior to detecting the input object in the first image, and that initial contact location is within the specified distance threshold. Or alternatively, when the input object is detected within the specified range in the first image and no force values indicate that the actual initial contact occurred outside the specified range. In each of these various embodiments the force values are used with the images to determine the gesture intended by the user.

[0079] The embodiments described herein avoid these potential problems by providing a mechanism for more reliably determining an initial contact location for an input object first detected in a first image of sensor values based at least in part on at least one force value preceding the first image of sensor values and the first image of sensor values. Specifically, by using the force values from one or more force sensors to disambiguate whether the input object actually made contact prior to being first detected in an image, and determining an estimate of the location of the initial contact. As was noted above, many types of force sensors can be utilized to provide force values to the processing system. By providing at least one force value between images generated by the sensor electrodes those force values can be used to determine if an input object made contact before it was detected in an image. Specifically, if applied force is detected shortly before the object was detected in an image it can be more reliably assumed that the input object may have actually contacted the input surface at a different location.

[0080] Furthermore, as was discussed above many typical force sensors can be configured to provide force values at a relatively high rate. Specifically, because of the amount of time and processing typically required to generate a full capacitive image (that will include numerous rows or columns of values, each generated at a different time) the rate at which such images may be generated is limited. In contrast, many force sensors can generate force values at considerably higher rate. This is particularly true of some capacitive force sensors, where each capacitive measurement may be used to generate a force value. Thus, by using such force sensors multiple force values can be generated between each generated image. Generating and using multiple force values between images can thus provide further ability to determine if an object had initially contacted the surface prior to be detected in an image.

[0081] A variety of different techniques can be used to determine an initial contact location for an input object first detected in a first image of sensor values based at least in part on at least one force value preceding the first image of sensor values and the first image of sensor values. As one example, locations of the input object in the first image and the second image are used and the time difference between such images to estimate a rate of motion of the input object across the sensing region. By estimating the rate of motion of the input object, and the time that contact was detected using the force sensor, an estimate of the initial contact location can be determined.

[0082] Turning now to FIG. 8, the input device 300 is illustrated with position 604, second position 606 and contact position 608 illustrated as crosses in the sensing region 306. As can be seen in FIG. 8, position 604 and second position 606 are separated by a distance D1, while contact position 608 and position 604 are separated by a distance D2. The time of the input object being at position 604, and the location of position 604 can be determined from the first image. Likewise, the time of the input object being at second position 606, and the location of second position 606 can be determined from the second image. Finally, the time of contact at contact position 608 can be determined from the force values.

[0083] With these values determined the position of the input object contact (i.e., contact position 608) can be accurately estimated. Specifically, because the distance D2 can be determined and used to estimate the velocity of the input object as it moved from position 604 and second position 606 the distance D1 can be estimated by assuming the velocity was relatively constant between all three positions. Furthermore, the location of contact position 606 can be estimated by assuming that the input object was traveling in a relatively straight line. Thus, from these determinations it can be determined if the initial contact at contact position 606 likely occurred in a region that would indicate a specific user interface action was intended to be performed.

[0084] For example, it can be determined if the initial contact position 608 occurred in an edge region proximate an edge of the sensor region 306. FIG. 8 illustrates the boundary of an exemplary edge region with line 610. As described above, such edge regions are commonly implemented to support a variety of user interface functions. For example, to provide a pull-down interface in response to a user initially contacting the sensor in the edge region and dragging the input object across the sensing region 306. In this case, by determining the location of contact position 608 it can be more reliably determined that the user intended to initiate such a pull-down interface. Thus, if the initial contact position 608 is determined to have occurred in the edge region the pull-down interface can be activated even though the input object was not detected in a capacitive image until it was outside the edge region at position 604. The input device 300 can thus more reliably respond to quickly moving fingers and other input objects that may not be detected at their initial locations.

[0085] As described above, the force values provided by the force sensors can be used with the images of sensor values to provide a variety of positional information. For example, positional information for an input object detected in a first image of sensor values based at least in part on the first image of sensor values and the force values. This positional information may be used to distinguish between a variety of different user interface actions. For example, determining if an input object detected in a first image of sensor values and an input object detected in a second image of sensor values performed a swipe across the input surface while remaining in contact with the input surface between the first image and the second image, or instead if the input object detected in the first image lifted from the input surface between the first image and the second image. As another example, determining if an initial contact location for an input object first detected in a first image of sensor values based at least in part on at least one force value preceding the first image of sensor values and the first image of sensor values.

[0086] The force values provide by the force sensors can also be used for additional functions. For example, one or more force values may themselves be used to generate positional information for the input object. This can be done using a variety of techniques, such as by estimating a deflection response or deformation response from the force values. Examples of these techniques are described in U.S. patent application Ser. No. 12/729,969, filed Mar. 23, 2010, entitled DEPRESSABLE TOUCH SENSOR; U.S. patent application Ser. No. 12/948,455, filed Nov. 17, 2010, entitled SYSTEM AND METHOD FOR DETERMINING OBJECT INFORMATION USING AN ESTIMATED DEFLECTION RESPONSE; U.S. patent application Ser. No. 12/968,000 filed Dec. 14, 2010, entitled SYSTEM AND METHOD FOR DETERMINING OBJECT INFORMATION USING AN ESTIMATED RIGID MOTION RESPONSE; and U.S. patent application Ser. No. 13/316,279, filed Dec. 9, 2011, entitled INPUT DEVICE WITH FORCE SENSING.

[0087] Thus, the embodiments and examples set forth herein were presented in order to best explain the present invention and its particular application and to thereby enable those skilled in the art to make and use the invention. However, those skilled in the art will recognize that the foregoing description and examples have been presented for the purposes of illustration and example only. The description as set forth is not intended to be exhaustive or to limit the invention to the precise form disclosed.

Claims

1. A processing system for an input device, the processing system comprising: a sensor module comprising sensor circuitry configured to: operate a plurality of sensor electrodes to generate images of sensor values indicative of objects in a sensing region proximate to an input surface at a first rate; operate at least one force sensor to generate force values indicative of force applied to the input surface at a second rate; a determination module configured to: determine if an input object detected in a first image of sensor values and an input object detected in a second image of sensor values remained in contact with the input surface between the first image and the second image based at least in part on the force values.

2. The processing system of claim 1 wherein the second rate is greater than the first rate.

3. The processing system of claim 1 wherein the first image of sensor values and the second image of second values comprise consecutive images generated by the determination module.

4. The processing system of claim 1 wherein the force sensor comprises a capacitive force sensor.

5. The processing system of claim 1 wherein the determination module is further configured to determine positional information for an input object based on the force values.

6. The processing system of claim 1 wherein the determination module is further configured to determine an initial contact location for an input object first detected in the first image of sensor values based at least in part on at least one force value preceding the first image of sensor values and the first image of sensor values.

7. The processing system of claim 1 wherein the determination module is configured to generate a first user interface action in response to a determination that the input object detected in the second image of sensor values remained in contact with the input surface between the first image and the second image and generate a second user interface action in response to a determination that the input object detected in the second image of sensor values did not remain in contact with the input surface between the first image and the second image.

8. A processing system for an input device, the processing system comprising: a sensor module comprising sensor circuitry configured to: operate a plurality of sensor electrodes to generate images of sensor values indicative of objects in a sensing region proximate to an input surface at a first rate; operate at least one force sensor to generate force values indicative of force applied to the input surface at a second rate; a determination module configured to: determine an initial contact location for an input object first detected in a first image of sensor values based at least in part on at least one force value preceding the first image of sensor values and the first image of sensor values.

9. The processing system of claim 8 wherein the second rate is greater than the first rate.

10. The processing system of claim 8 wherein the determination module is further configured to initiate an edge user interface action based on the initial contact location in response to the initial contact location being in an edge region.

11. The processing system of claim 8 wherein the determination module is further configured to not initiate an edge user interface action in response to a determination that an initial contact within an edge region did not occur prior to the first image of sensor values.

12. The processing system of claim 8 wherein the force sensor comprises a capacitive force sensor.

13. The processing system of claim 8 wherein the determination module is further configured to generate positional information for the input object using the force values.

14. The processing system of claim 8 wherein the determination module is further configured to determine if an input object detected in the first image of sensor values and an input object detected in a second image of sensor values remained in contact with the input surface between the first image and the second image based at least in part on the force values.

15. An input device comprising: an input surface a plurality of capacitive sensor electrodes proximate to the input surface; at least one force sensor coupled to the input surface; a processing system operatively coupled to the plurality of capacitive sensor electrodes and the at least one force sensor, the processing system configured to: operate the plurality of capacitive sensor electrodes to generate images of sensor values indicative of objects in a sensing region proximate to the input surface at a first rate; operate the at least one force sensor to generate force values indicative of force applied to the input surface at a second rate; determine if an input object detected in a first image of sensor values and an input object detected in a second image of sensor values remained in contact with the input surface between the first image and the second image based at least in part on the force values.

16. The input device of claim 15 wherein the second rate is greater than the first rate.

17. The input device of claim 15 wherein the first image of sensor values and the second image of second values comprise consecutive images generated by the processing system.

18. The input device of claim 15 wherein the force sensor comprises a capacitive force sensor.

19. The input device of claim 15 wherein the processing system is further configured to determine positional information for an input object based on the force values.

20. The input device of claim 15 wherein the processing system is further configured to determine an initial contact location for an input object first detected in the first image of sensor values based at least in part on at least one force value preceding the first image of sensor values and the first image of sensor values.

21. The input device of claim 15 wherein the processing system is configured to generate a first user interface action in response to a determination that the input object detected in the second image of sensor values remained in contact with the input surface between the first image and the second image and generate a second user interface action in response to a determination that the input object detected in the second image of sensor values did not remain in contact with the input surface between the first image and the second image.

22. A method of determining input in an input device, the method comprising: operating a plurality of sensor electrodes to generate images of sensor values indicative of objects in a sensing region proximate to an input surface at a first rate; operating at least one force sensor to generate force values indicative of force applied to the input surface at a second rate; determining an initial contact location for an input object first detected in a first image of sensor values based at least in part on at least one force value preceding the first image of sensor values and the first image of sensor values; and generating a user interface action based at least in part on the initial contact location.

23. The method of claim 22 wherein the second rate is greater than the first rate.

24. The method of claim 22 wherein the generating the user interface action based at least in part on the initial contact location comprises initiating an edge user interface action based on the initial contact location in response to the initial contact location being in an edge region.

25. The method of claim 22 wherein the force sensor comprises a capacitive force sensor.

26. The method of claim 22 further comprising generating positional information for the input object using the force values.

27. The method of claim 22 further comprising determining if an input object detected in the first image of sensor values and an input object detected in a second image of sensor values remained in contact with the input surface between the first image and the second image based at least in part on the force values.