Methods and apparatus for performing capacitive touch sensing and proximity detection

#Embodiments relate to capacitive touch sensor devices, and more particularly to methods and apparatus for configuring capacitive touch sensor devices that include a proximity detection feature.

#Capacitive touch sensor devices have been incorporated into a variety of consumer electronics, including cellular telephones, computers, portable entertainment devices, appliances, and touch screens, to name a few. At a minimum, a capacitive touch sensor device includes one or more touch sensors (or “electrodes”), each of which is configured to indicate a capacitance change when the sensor is touched (e.g., by a stylus or a user's finger). Each sensor may be associated with a distinct user input, and the detection of a touch by a particular sensor may initiate a responsive process in the device. For example, to enable a user to make a telephone call, a cellular telephone with a relatively simple user interface may include an array of twelve sensors, with ten of the sensors being associated with each of the numbers from 0 to 9, an eleventh sensor being associated with a “SEND” key, and a twelfth sensor being associated with an “END” key. Each time the user touches a sensor associated with a number, the device displays the number and stores it in a register. When the register includes a set of numbers associated with a remote device (e.g., a telephone number), and the user touches a sensor associated with the “SEND” key, the device may initiate a connection with a communication network (e.g., a cellular telephone network). The device additionally may send to the network the set of numbers in the register, thus enabling the network to initiate a communication session with the remote device.

#Some capacitive touch sensor devices also include a “proximity sensor” (or “proximity electrode”), which is distinct from the touch sensors, and which is configured to detect the approach or proximity of an object (e.g., a stylus or a user's finger) by sensing changes in capacitance, as opposed to detecting an actual touch. An indication by a proximity sensor that an object is approaching also may initiate a responsive process in the device. For example, when a proximity sensor indicates that an object is approaching, the device may cause a backlight to activate, thus illuminating a display screen. Such a feature may enable the device to conserve power, among other things, and proximity sensors have been used to initiate a variety of processes. A proximity sensor typically includes a relatively large, stand-alone electrode. Because of their size, proximity sensors typically are not included in devices that have crowded touch sensor arrays and/or severe size constraints.

#FIG. 1 illustrates a plan view of a example electronic device, according to an example embodiment;

#FIG. 2 illustrates a simplified schematic block diagram of a portion of an electronic system within which a capacitive touch and proximity sensor system is incorporated, according to an example embodiment;

#FIG. 3 illustrates a simplified schematic block diagram of a capacitive touch and proximity sensor system, according to an example embodiment;

#Embodiments include methods and apparatus by which proximity detection may be incorporated into a device, even when characteristics of the device do not lend themselves to the inclusion of relatively large, proximity sensors. A particular embodiment includes creating a “pseudo” or “proximity” electrode as a combination of a plurality of individual electrodes, where the proximity electrode functions to provide proximity detection. In addition, embodiments include methods and apparatus for filtering sensor data from the individual electrodes differently from filtering sensor data from the proximity electrode, as the characteristics of touch sensing and proximity sensing may have different frequency characteristics. The various embodiments enable a proximity detection feature to be easily incorporated into a wide variety of device types, including devices that have crowded touch sensor arrays and/or severe size constraints (e.g., cellular telephones and other portable devices).

#FIG. 1 illustrates a plan view of a example electronic device 100 that includes, on an input face 106 of the device 100, multiple, individual touch sensor electrodes 102 (“electrodes”) and a display 104, according to an example embodiment. Electrodes 102 are arranged in an array 108 having “X” columns and “Y” rows. For purposes of example only, array 108 includes ten columns and five rows of electrodes 102. The designation “i,j” may be used throughout this description to refer to a particular electrode of an array (e.g., array 108), where “i” indicates a column number, and “j” indicates a row number. Accordingly, for example, each electrode of array 108 can be identified by a value from 1,1 . . . i,j . . . X,Y. Although device 100 is shown to include fifty electrodes 102 in an array 108 of ten columns and five rows, it is to be understood that a device may include more or fewer electrodes, which may be arranged in an array of more or fewer columns and/or rows, and/or which may be arranged in a configuration other than an array, in other embodiments. In addition, the electrodes may include free standing electrodes, such as are shown in FIG. 1, and/or the electrodes may be incorporated in a display screen in the form of virtual electrodes.

#The device configuration illustrated in FIG. 1 may correspond, for example, to a cellular telephone or micro-computer. It is to be understood that the configuration of FIG. 1 is provided for example purposes only, and that embodiments may be incorporated into any type of device intended to receive user inputs via contact with and/or proximity to an electrode by an “activation element.” As used herein, the term “activation element” is intended to be interpreted broadly and include any object by which a user interacts with electrodes (e.g., a finger, an ear, a cheek, a hand, a stylus or various other instruments adapted for approaching or touching one or more electrodes). For convenience of explanation and not intended to be limiting, it is assumed in the discussion that follows that electric field sensing is used to determine whether a particular electrode is being approached or contacted by an activation element. However, persons of skill in the art will understand, based on the description herein, that other types of proximity and/or contact sensing may also be employed. Non-limiting examples of useful alternative sensing techniques include optical sensing, magnetic field sensing, and combinations of optical, electric, and/or magnetic field sensing.