Capacitive sensing for determining mass displacement and direction

A capacitive sensing system for determining mass displacement and direction is disclosed. In an embodiment, a capacitive sensing system for sensing mass displacement and direction comprises: a mass; a periodic drive electrode pattern formed on or attached to the mass; a sensing electrode array positioned relative to the periodic electrode pattern, the sensing electrode array operable to sense a capacitance in an overlapping area between the periodic drive electrode pattern and the sensing electrode array; and a capacitive sensing circuit coupled to at least the sensing electrode array, the capacitive sensing circuit operable to generate a periodic signal based on the sensed capacitance, to determine a phase shift in the periodic signal in response to the periodic drive electrode pattern moving relative to the sensing electrode array, and to determine, based on the phase shift, a displacement and direction of the mass on a movement axis.

TECHNICAL FIELD

This disclosure relates generally to capacitive sensing systems.

BACKGROUND

Mobile devices often include a haptic system that is configured to provide a tactile feedback sensation such as a vibration or other physical sensation to a user touching or holding the mobile device. The haptic system can include an input surface and one or more actuators, such as piezoelectric transducers, electromechanical devices, and/or other vibration inducing devices, that are mechanically connected to the input surface. Drive electronics coupled to the one or more actuators cause the actuators to induce a vibratory response into the input surface, providing a tactile sensation to a user touching or holding the device. A conventional haptic system may include a mass in a housing that moves or oscillates to induce the vibratory response. A transducer can be included in the housing that varies its output voltage in response to changes in a magnetic field as the mass moves within the housing. The output voltage can be used in a control application to determine the position of the mass which can be used by the control application to provide stability to the haptic system.

SUMMARY

A capacitive sensing system and method for determining mass displacement and direction is disclosed.

In an embodiment, a capacitive sensing system for sensing mass displacement and direction comprises: a mass; a periodic drive electrode pattern formed on or attached to the mass; a sensing electrode array positioned relative to the periodic electrode pattern, the sensing electrode array operable to sense a capacitance in an overlapping area between the periodic drive electrode pattern and the sensing electrode array; and a capacitive sensing circuit coupled to at least the sensing electrode array, the capacitive sensing circuit operable to generate a periodic signal based on the sensed capacitance, to determine a phase shift in the periodic signal in response to the periodic drive electrode pattern moving relative to the sensing electrode array, and to determine, based on the phase shift, a displacement and direction of the mass on a movement axis.

In an embodiment, a method for sensing mass displacement and direction comprises: sensing, by a sensing electrode array, capacitance in an overlapping area between a drive electrode or a periodic drive electrode pattern formed on or attached to a mass and at least one sensing electrode array; generating at least one periodic signal indicative of mass motion; determining at least one phase shift in the at least one periodic signal; and determining, based on the at least one phase shift, at least one displacement and at least one direction of the mass on at least one movement axis.

In an embodiment, a capacitive sensing system for sensing mass displacement and direction comprises: a mass having a surface with a two-dimensional periodic drive electrode pattern formed on or attached to the surface; a first sensing electrode array positioned relative to the periodic electrode pattern, the first sensing electrode array operable to sense a first capacitance associated with a first overlapping area between the periodic drive electrode pattern and the first sensing electrode array; a second sensing electrode array positioned relative to the periodic electrode pattern, the second sensing electrode array operable to sense a second capacitance associated with a second overlapping area between the periodic drive electrode pattern and the second sensing electrode array; and a capacitive sensing circuit coupled to the at least one of the first and second sensing electrode arrays, the capacitive sensing circuit operable to generate periodic signals based on the sensed capacitance, to determine phase shifts in the periodic signals due to the periodic drive electrode pattern moving relative to the sensing electrode arrays, and to determine, based on the phase shifts, displacements and directions of the mass on two or more movement axes.

In an embodiment, a capacitive sensing system for sensing mass movement and direction comprises: a movable mass; a drive electrode formed on or attached to the mass; a sensing electrode array positioned relative to the drive electrode and operable to sense capacitance in an overlapping area between the drive electrode and the sensing electrode array; and a capacitive sensor coupled to the sensing electrode array and operable to determine a centroid of a capacitance distribution across a number of sensing electrodes of the sensing electrode array, to compute a shift in location of the centroid along the sensing electrode array due to the mass moving relative to the sensing electrode array, and determining, based on the centroid shift, a displacement and direction of the mass on a movement axis.

In an embodiment, a haptic system comprises: a housing; a movable mass fixed in the housing and operable to move within the housing on a movement axis, one or more drive electrodes or periodic drive electrode patterns formed on or attached to the mass; one or more sensing electrode arrays positioned in the housing relative to the drive electrode or drive periodic electrode pattern, the one or more sensing electrode arrays operable to sense capacitance in one or more overlapping areas between the drive electrode or periodic drive electrode pattern and the one or more sensing electrode arrays; and a capacitive sensing circuit coupled to at least one of the sensing electrode arrays, the capacitive sensing circuit operable to generate one or more periodic signals based on the sensed capacitance, to determine one or more phase shifts in the one or more periodic signals in response to the drive electrode or the periodic drive electrode pattern moving relative to the one or more sensing electrode arrays, and to determine, based on the one or more phase shifts, a displacement and direction of the mass on one or more movement axes.

Particular embodiments disclosed herein provide one or more of the following advantages. The capacitive sensing system and method disclosed herein is environment robust, easy to implement and cost effective. The capacitive sensing system does not require a sealed environment to prevent rust, light or other leakage. The capacitive sensing system does not require a special mass or sensing electrode design.

The details of the disclosed embodiments are set forth in the accompanying drawings and the description below. Other features, objects and advantages are apparent from the description, drawings and claims.

The same reference symbol used in various drawings indicates like elements.

DETAILED DESCRIPTION

Embodiments are disclosed for capacitive sensing systems and methods for sensing mass displacement and direction on one or more movement axes. The capacitive sensing systems can be used in any device that senses object displacement and/or direction, such as, for example, a haptic feedback system used in electronic devices, such as a smartphone, tablet computer, laptop or wearable computer. The capacitive sensing systems include a periodic drive electrode pattern formed on or attached to a movable mass. The periodic drive electrode pattern is positioned relative to a sensing electrode or sensing electrode array so that a dominant capacitance in an overlapping area between the periodic drive electrode pattern and the sensing electrode or sensing electrode array can be sensed by a capacitive sensor. A periodic signal representing the sensed capacitance is generated by the capacitive sensor. The periodic signal has a similar periodic profile (e.g., a sinewave or triangular wave profile) as the periodic drive electrode pattern. If the mass is displaced on a movement axis, a phase shift in the periodic signal reflects the displacement and a sign of the phase shift reflects a direction of the displacement on the movement axis.

In an embodiment, the sensitivity of the periodic signal strength to changes in distance between the drive electrode pattern and the sensing electrode or sensing electrode array is compensated by adding another periodic drive electrode pattern and sensing electrode or sensing electrode arrays to the capacitive sensing system so that when the distance between one set of the electrodes is increasing the distance between the other set of electrodes is decreasing. Both sets of electrodes can be coupled to the same capacitive sensor which is operable to adjust the sensitivity of the signals.

Example Capacitive Sensing System

FIG. 1is a perspective drawing of an example mutual capacitive sensing system100for sensing mass displacement and direction, according to an embodiment. Capacitive sensing system100includes mass102, sensor substrate104, periodic drive electrode pattern106, sensing electrode array108and capacitive sensor circuit110(e.g., a chipset). Mass102is operable to move along movement axis112. In some embodiments, mass102is physically constrained by a shaft or other structure to move only along movement axis112. Periodic drive electrode pattern106is disposed on or attached to a surface of mass102. Mass102and sensor substrate104are separated by a distance d, as shown inFIG. 4. Mass102is positioned relative to sensor substrate104so that drive electrode pattern106at least partially overlaps at least a portion of sensing electrode array108. Capacitive sensor circuit110is coupled to drive electrode pattern106and sensing electrode array108.

In some embodiments, capacitive sensing system100is included in a haptic system. For example, system100can be used in a haptic control system that prevents a moving mass or actuator from exceeding certain displacement limits to prevent damage or instability to the haptic system. Capacitive sensing system100, however, can also be used in any system that senses mass, actuator or object movement.

FIG. 2is a perspective drawing of an example self-capacitance sensing system200for sensing mass displacement and direction, according to an embodiment. Capacitive sensing system200includes mass202, sensor substrate204, periodic drive electrode pattern206, sensing electrode array208and capacitive sensor circuit210. Mass202is operable to move along movement axis212. System200is similar to system100but operates using the principal of self-capacitance. Only sensing electrode array208is coupled to capacitive sensor circuit210.

FIG. 3is a top plan view of the example periodic drive electrode pattern106shown inFIG. 1, according to an embodiment. In this example embodiment, pattern106is a sinewave. Other one-dimensional (1D) and two-dimensional (2D) periodic patterns can be used other than a sinewave, such as a periodic triangle waveform. In some embodiments, a 2D periodic pattern can be used to determine mass displacement and direction along two movement axes as described in reference toFIG. 6BandFIGS. 7B, 7C.

A cycle of periodic drive electrode pattern106has a width W/2 and length L. In this example embodiment, sensing electrode array108includes N (e.g., N=8) sensing electrodes which collectively span length L, and sensing electrode array108has dimensions of L×W. These dimensions allow a cycle of the periodic drive electrode pattern to at least partially overlap with at least some portions of the N sensing electrodes, resulting in a dominant capacitance build up in overlapping area300.

FIG. 5Aillustrates the calculation of mass displacement and direction on a single movement axis using capacitive sensing, according to an embodiment. As shown inFIG. 5A, a cycle of periodic drive electrode pattern500has a length L and a width W/2. The capacitance for the ith sensing electrode of a total of N sensing electrodes in a sensing electrode array can be calculated using Equation [1]:

Ci=ɛ⁢∫x+(i-1)⁢L/Nx+iL/N⁢[W2⁢sin⁡(2⁢⁢π⁢⁢xL-π2)+w2]·dxd,[1]
where d is the distance between the drive electrode pattern and the ith sensing electrode as shown inFIG. 4and ε is the permittivity of dielectric. The capacitance in Equation [1] is calculated by integrating overlapping area502for each of the N sensing electrodes.

FIG. 5Bshows two periodic signal plots for two different positions of the mass on a single movement axis x. In this example, the sensing electrode array includes 8 sensing electrodes (N=8). A first signal plot504is shown for a first position xoon movement axis x that is determined at a first time t0using Equation [1]. A second plot506is shown for position x1on the movement axis x that is determined at a second time t1after the first time t0using Equation [1]. Assuming that the mass was displaced during the time interval t1-t0, the displacement x1-x0of the mass on the movement axis x is given by Equation [2]:

x1=x0=Δ⁢⁢φ2⁢⁢π⁢L,[2]
where Δφ is a phase shift between the two periodic signals for the two positions. Accordingly, the displacement of the mass on movement axis x is proportional to the phase shift Δφ between the periodic signals. Additionally, the sign of the phase shift indicates the direction of displacement on the movement axis x.

FIGS. 6A and 7Aillustrate a periodic drive electrode sensor pattern and phase shift calculation, respectively for a single movement axis606, according to an embodiment. Referring toFIG. 6A, periodic drive electrode pattern602is disposed on movable mass600, creating an overlapping area608with sensing electrode array604. In this example, a periodic triangle waveform is used rather than a sinewave. The capacitance for the ith sensing electrode can be given by Equation [3]:

FIG. 7Acorresponds toFIG. 6Aand shows two periodic signal plots for two different positions of the mass on the movement axis x. A first signal plot702is shown for position xothat is determined at a first time t0using Equation [3] and assuming a sensing electrode array with 8 sensing electrodes. A second signal plot704is shown for position x1that is determined at a second time t1after the first time t0using Equation [3]. Assuming that the mass moved during the time interval t1-t0, the displacement x1-x0of the mass on the movement axis x is given by Equation [2].

FIG. 6Billustrates a periodic drive electrode pattern for a two-axis sensor, according to an embodiment. A 2D periodic drive electrode pattern612disposed on movable mass610creates an overlapping area617with sensing electrode array614and an overlapping area611with sensing electrode array615. Sensing electrode array615is rotated Ω degrees (e.g., 90° clockwise) relative to sensing electrode array614. However, the sensing electrode arrays614,615can be oriented with respect to each other at any desired angle. With the 2D pattern612and arrangement of sensing arrays614,615, capacitive measurements can be made for determining the displacement and direction of a mass on two orthogonal movement axes616,618.

FIG. 7Bcorresponds toFIG. 6Band shows two periodic signal plots for two different positions of the movable mass on the movement axis x. A first signal plot706is shown for position xothat is determined at a first time t0using a variation of Equation [3], assuming a sensing electrode array with 8 sensing electrodes. A second signal plot708is shown for position x1that is determined at a second time t1after the first time t0using Equation [3]. Assuming that the mass moved during the time interval t1-t0, the displacement traveled x1-x0by the mass along the movement axis x is given by Equation [2].

FIG. 7Calso corresponds toFIG. 6Band shows two signal plots for two different positions of the movable mass on the movement axis y. A first signal plot710is shown for position yothat is determined at a first time t0using Equation [3], assuming a sensing electrode array with 8 sensing electrodes. A second signal plot712is shown for position y1that is determined at a second time t1after the first time t0using Equation [3]. Assuming that the mass moved during the time interval t1-t0, the displacement y1-y0of the mass on the movement axis y is given by Equation [2].

FIG. 8illustrates an alternative embodiment for a capacitive sensing system for sensing object movement using a mutual capacitance sensing electrode array, according to an embodiment. In this embodiment, mass800can move along movement axis806in either direction. Drive electrode802is attached to mass800and overlaps sensing electrode array804. In this arrangement the dominant capacitance will be directly under drive electrode802. Capacitance measurements are taken at the sensing electrodes of sensing electrode array804and a location of a centroid808representing the peak capacitance is determined. If during a time interval t1-t0, mass800moves along movement axis806, the centroid location will shift. The difference between centroid locations at times t0and t1is proportional to the displacement moved by mass800along movement axis806. In an embodiment, tracking the centroid808can be implemented as follows. The x-axis number for each sensing electrode in sensing electrode array804is xi=(i−1)*L/N+0.5*L/N (center of sensing electrode) and the signal at a certain location of mass800on the x-axis for each sensing electrode is si. Then the x-coordinate of the peak point or centroid808(xp, yp) can be obtained by interpolating xiand si. If xp0is the t0position reading of mass800, and xp1is the t1position reading of mass800, the displacement of mass800is xp1-xp0. An advantage of this embodiment is the drive electrode802is simple and less space is needed for the capacitive sensing system.

FIG. 9illustrates an alternative embodiment for a capacitive sensing system for sensing object movement using a self-capacitance sensing electrode array, according to an embodiment. Note that the drive electrode902is coupled to ground for self-capacitance. In this embodiment, mass900can move along movement axis906in either direction. Drive electrode902is attached to mass900and overlaps sensing electrode array904. In this arrangement the dominant capacitance will be directly under drive electrode902. Capacitance measurements are taken at the sensing electrodes of sensing electrode array904and a centroid908is determined that represents the peak capacitance. If during a time interval t1-t0, mass900moves along movement axis906, the centroid location will shift. The difference between centroid locations at times t0and t1is proportional to the displacement moved by mass900on movement axis906. Centroid908can be determined in a similar manner as centroid808as described in reference toFIG. 8.

FIG. 10illustrates an example haptic system1000including a single drive electrode and a single sensing electrode array. Haptic system1000includes movable mass1006, shaft1008, drive electrode1002, sensing electrode1004and springs1010,1012. A capacitive sensing circuit is included on sensing electrode1004. All of these components are located within housing1016. Flexible circuit1014connects drive electrode1002to sensing electrode array1004. Sensing electrode array1004is coupled to an external motor controller. Haptic system1000is environment robust, easy to implement and cost effective. The capacitive sensing system used by haptic feedback system1000does not require a sealed environment to prevent rust, light or other leakage. The capacitive sensing system does not require a special mass design.

FIG. 11illustrates an example haptic system1100including two drive electrodes and two sensing electrode arrays, according to an embodiment. Haptic system1100includes mass1106, drive electrodes1102a,1102b, sensing electrode arrays1104a,1104b, springs1110,1112and analog front end (AFE)1116. Using two sensing electrode arrays1104a,1104ballows for compensation of variations in the distances d1and d2. Sensing electrode arrays1104a,1104bare each coupled to AFE1116which is operable to provide the compensation of the variations in the distances d1and d2. Haptic system1100is environment robust, easy to implement and cost effective. The capacitive sensing system used by haptic feedback system1100does not require a sealed environment to prevent rust, light or other leakage. The capacitive sensing system does not require a special mass design. As the mass vibrates in a vertical direction, the value of distances d1and d2will change in opposite directions but the sum of d1and d2will remain constant. Since the total capacitance is

Ctot=ɛ⁢Sd⁢⁢1+ɛ⁢Sd⁢⁢2,
the total capacitance will not decrease due to mass vertical movement. This is not the case with only one set of electrodes. AFE1116will get a higher signal-to-noise ratio (SNR), and the position calculated by Equation [2] is more accurate. The ith electrode from sensing electrode array1104acan be connected to the ith electrode from sensing electrode array1104bso that only one AFE1116is required.

Example Capacitive Sensing Process

FIG. 12is a flow diagram of an example capacitive sensing process1200for sensing mass movement and direction, according to an embodiment. Process1200can be implemented by mobile device architecture1300, as described in reference toFIG. 13.

In some embodiments, process1200can begin by sensing capacitance (e.g., sense a dominant capacitance) in one or more overlapping areas between one or more periodic drive electrode patterns disposed on a movable mass and one or more sensing electrodes or sensing electrode arrays (1202). For example, the periodic drive electrode pattern can be a 1D or 2D sinewave or a periodic triangle waveform. Process1200can continue by generating one or more periodic signals based on the capacitances measured on one or more sensing electrodes of the one or more sensing electrode arrays in the overlapping area (1204). Process1200can continue by determining one or more phase shifts of the periodic signals due to movement of the mass on one or more movement axes (1206). Process1200can continue by determining, based on the one or more phase shifts, a displacement and direction of the mass on one or more movement axes (1208). For example, the magnitude of the phase shift indicates a displacement of the mass on the movement axis and the sign of the phase shift indicates the direction of mass on the movement axis.

Example Device Architecture

FIG. 13is a block diagram of an example device architecture for implementing the capacitive sensing systems described in reference toFIGS. 1-12, according to an embodiment. Architecture1300may be implemented in any mobile device for generating the features and processes described in reference toFIGS. 1-12, including but not limited to smart phones and wearable computers (e.g., smart watches, fitness bands). Architecture1300may include memory interface1302, data processor(s), image processor(s) or central processing unit(s)1304, and peripherals interface1306. Memory interface1302, processor(s)1304or peripherals interface1306may be separate components or may be integrated in one or more integrated circuits. One or more communication buses or signal lines may couple the various components.

Sensors, devices, and subsystems may be coupled to peripherals interface1306to facilitate multiple functionalities. For example, motion sensor(s)1310, light sensor1312, and proximity sensor1314may be coupled to peripherals interface1306to facilitate orientation, lighting, and proximity functions of the device. For example, in some embodiments, light sensor1312may be utilized to facilitate adjusting the brightness of touch surface1346. In some embodiments, motion sensor(s)1310(e.g., an accelerometer, rate gyroscope) may be utilized to detect movement and orientation of the device. Accordingly, display objects or media may be presented according to a detected orientation (e.g., portrait or landscape). Haptic feedback system1317, under the control of haptic feedback instructions1372, provides the features and performs the processes described in reference toFIGS. 1-12, such as, for example, implementing a capacitive sensing system. Haptic feedback system1317can include an input surface and one or more actuators, such as piezoelectric transducers, electromechanical devices, and/or other vibration inducing devices, that are mechanically connected to the input surface. Drive electronics coupled to the one or more actuators cause the actuators to induce a vibratory response into the input surface, providing a tactile sensation to a user touching or holding the device.

Other sensors may also be connected to peripherals interface1306, such as a temperature sensor, a barometer, a biometric sensor, or other sensing device, to facilitate related functionalities. For example, a biometric sensor can detect fingerprints and monitor heart rate and other fitness parameters.

Location processor1315(e.g., GNSS receiver chip) may be connected to peripherals interface1306to provide geo-referencing. Electronic magnetometer1316(e.g., an integrated circuit chip) may also be connected to peripherals interface1306to provide data that may be used to determine the direction of magnetic North. Thus, electronic magnetometer1316may be used as an electronic compass.

Camera subsystem1320and an optical sensor1322, e.g., a charged coupled device (CCD) or a complementary metal-oxide semiconductor (CMOS) optical sensor, may be utilized to facilitate camera functions, such as recording photographs and video clips.

Communication functions may be facilitated through one or more communication subsystems1324. Communication subsystem(s)1324may include one or more wireless communication subsystems. Wireless communication subsystems1324may include radio frequency receivers and transmitters and/or optical (e.g., infrared) receivers and transmitters. Wired communication systems may include a port device, e.g., a Universal Serial Bus (USB) port or some other wired port connection that may be used to establish a wired connection to other computing devices, such as other communication devices, network access devices, a personal computer, a printer, a display screen, or other processing devices capable of receiving or transmitting data.

The specific design and embodiment of the communication subsystem1324may depend on the communication network(s) or medium(s) over which the device is intended to operate. For example, a device may include wireless communication subsystems designed to operate over a global system for mobile communications (GSM) network, a GPRS network, an enhanced data GSM environment (EDGE) network, IEEE802.xx communication networks (e.g., Wi-Fi, Wi-Max, ZigBee™), 3G, 4G, 4G LTE, code division multiple access (CDMA) networks, near field communication (NFC), Wi-Fi Direct and a Bluetooth™ network. Wireless communication subsystems1324may include hosting protocols such that the device may be configured as a base station for other wireless devices. As another example, the communication subsystems may allow the device to synchronize with a host device using one or more protocols or communication technologies, such as, for example, TCP/IP protocol, HTTP protocol, UDP protocol, ICMP protocol, POP protocol, FTP protocol, IMAP protocol, DCOM protocol, DDE protocol, SOAP protocol, HTTP Live Streaming, MPEG Dash and any other known communication protocol or technology.

Audio subsystem1326may be coupled to a speaker1328and one or more microphones1330to facilitate voice-enabled functions, such as voice recognition, voice replication, digital recording, and telephony functions.

I/O subsystem1340may include touch controller1342and/or other input controller(s)1344. Touch controller1342may be coupled to a touch surface1346. Touch surface1346and touch controller1342may, for example, detect contact and movement or break thereof using any of a number of touch sensitivity technologies, including but not limited to, capacitive, resistive, infrared, and surface acoustic wave technologies, as well as other proximity sensor arrays or other elements for determining one or more points of contact with touch surface1346. In one embodiment, touch surface1346may display virtual or soft buttons and a virtual keyboard, which may be used as an input/output device by the user.

Other input controller(s)1344may be coupled to other input/control devices1348, such as one or more buttons, rocker switches, thumb-wheel, infrared port, USB port, and/or a pointer device such as a stylus. The one or more buttons (not shown) may include an up/down button for volume control of speaker1328and/or microphone1330.

In some embodiments, device1300may present recorded audio and/or video files, such as MP3, AAC, and MPEG video files. In some embodiments, device1300may include the functionality of an MP3 player and may include a pin connector for tethering to other devices. Other input/output and control devices may be used.

Memory interface1302may be coupled to memory1350. Memory1350may include high-speed random access memory or non-volatile memory, such as one or more magnetic disk storage devices, one or more optical storage devices, or flash memory (e.g., NAND, NOR). Memory1350may store operating system1352, such as Darwin, RTXC, LINUX, UNIX, OS X, iOS, WINDOWS, or an embedded operating system such as VxWorks. Operating system1352may include instructions for handling basic system services and for performing hardware dependent tasks. In some embodiments, operating system1352may include a kernel (e.g., UNIX kernel).

Memory1350may also store communication instructions1354to facilitate communicating with one or more additional devices, one or more computers or servers, including peer-to-peer communications. Communication instructions1354may also be used to select an operational mode or communication medium for use by the device, based on a geographic location (obtained by the GPS/Navigation instructions1368) of the device.

Memory1350may include graphical user interface instructions1356to facilitate graphic user interface processing, including a touch model for interpreting touch inputs and gestures; sensor processing instructions1358to facilitate sensor-related processing and functions; phone instructions1360to facilitate phone-related processes and functions; electronic messaging instructions1362to facilitate electronic-messaging related processes and functions; web browsing instructions1364to facilitate web browsing-related processes and functions; media processing instructions1366to facilitate media processing-related processes and functions; GNSS/Navigation instructions1368to facilitate GNSS (e.g., GPS, GLOSSNAS) and navigation-related processes and functions; camera instructions1370to facilitate camera-related processes and functions; and haptic feedback instructions1372for commanding or controlling haptic feedback system1317and to provide the features and performing the processes described in reference toFIGS. 1-12.

Each of the above identified instructions and applications may correspond to a set of instructions for performing one or more functions described above. These instructions need not be implemented as separate software programs, procedures, or modules. Memory1350may include additional instructions or fewer instructions. Furthermore, various functions of the device may be implemented in hardware and/or in software, including in one or more signal processing and/or application specific integrated circuits (ASICs).

A number of embodiments have been described. Nevertheless, it will be understood that various modifications may be made. Elements of one or more embodiments may be combined, deleted, modified, or supplemented to form further embodiments. In yet another example, the logic flows depicted in the figures do not require the particular order shown, or sequential order, to achieve desirable results. In addition, other steps may be provided, or steps may be eliminated, from the described flows, and other components may be added to, or removed from, the described systems. Accordingly, other embodiments are within the scope of the following claims.