Sensor matrix pad for performing multiple capacitive sensing techniques

Embodiments in the present disclosure use various individual electrodes in a capacitive sensing pixel of an electrode matrix to perform two different techniques of capacitive sensing. For example, a capacitive sensing pixel may include at least two sensor electrodes that may be driven different by a processing system depending on the current capacitive technique being used to user interaction. When performing absolute capacitive sensing, a first one of the sensor electrodes may be driven with a modulated signal in order to measure a change in absolute capacitance between the driven sensor electrode and an input object. Alternatively, when performing transcapacitance sensing, the first sensor electrode is driven with a transmitter signal while a resulting signal is measured on a second sensor electrode in the capacitive pixel. In this manner, the individual electrodes in a capacitive sensing pixel may be driven differently depending on the current capacitive sensing technique.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the present invention generally relate to performing capacitive sensing using the same sensor electrode in two different modes of operation.

2. Description of the Related Art

SUMMARY OF THE INVENTION

One embodiment described herein is an input device that includes a display device, a plurality of sensor electrodes that establish a sensing region of the input device, and a processing system coupled to the plurality of sensor electrodes. The processing system is configured to perform absolute capacitive sensing during a first time period by driving a modulated signal on at least one of a first sensor electrode of the plurality of sensor electrodes and a second sensor electrode of the plurality of sensor electrodes to determine a change in absolute capacitance between the driven sensor electrode and an input object. Moreover, the first and second sensor electrodes are disposed on a same plane in the input device. The processing system is also configured to perform transcapacitance sensing during a second time period by driving a transmitter signal onto the first sensor electrode and measuring a resulting signal on the second sensor electrode.

Another embodiment described herein is a method for performing capacitive sensing comprising a plurality of sensor electrodes that establish a sensing region of the input device. The method includes performing absolute capacitive sensing during a first time period by driving a modulated signal on at least one of a first sensor electrode of the plurality of sensor electrodes and a second sensor electrode of the plurality of sensor electrodes to determine a change in absolute capacitance between the driven sensor electrode and an input object. Moreover, the first and second sensor electrodes are disposed on a same plane in the display device. The method also includes performing transcapacitance sensing during a second time period by driving a transmitter signal onto the first sensor electrode and measuring a resulting signal on the second sensor electrode.

Another embodiment described herein is a processing system for a capacitive sensing device comprising a sensing region. The processing system includes a sensor module coupled to a plurality of sensor electrodes, the sensor module configured to perform a first mode of capacitive sensing during a first time period by driving a modulated signal on at least one of a first sensor electrode of the plurality of sensor electrodes and a second sensor electrode of the plurality of sensor electrodes and perform a second, different mode of capacitive sensing during a second time period using at least one of the first and second sensor electrodes. In addition, the second sensor electrode at least partially encircles the first sensor electrode.

DETAILED DESCRIPTION

Various embodiments of the present technology provide input devices and methods for improving usability. Specifically, the various individual electrodes in a capacitive sensing pixel of an electrode matrix may be used to perform two different techniques of capacitive sensing. In one example, a capacitive sensing pixel may include at least two sensor electrodes are driven differently by a processing system depending on the current capacitive sensing technique being employed. For instance, when performing absolute capacitive sensing, a first one of the sensor electrodes in the capacitive pixel may be driven with a modulated signal in order to measure a change in absolute capacitance between the driven sensor electrode and an input object. A second one of the sensor electrodes may be driven using a guarding signal or left electrically floating. Alternatively, when performing transcapacitance sensing, the first sensor electrode is driven with a transmitter signal while a resulting signal is measured on the second sensor electrode. In this manner, the individual electrodes in a capacitive sensing pixel may be driven differently depending on the current capacitive sensing technique.

The electrode matrix may include a plurality of capacitive sensing pixels arranged in a grid. In one embodiment, the capacitive sensing pixels may be disposed on the same plane in the input device. The capacitive pixels, for example, may be arranged on the same plane in rows and columns that are either aligned or staggered (e.g., adjacent sensing pixels may be offset). The individual electrodes in the capacitive sensing pixels are not limited to any particular shape, but in one embodiment, the individual electrodes may form concentric shapes where one sensor electrode at least partially encircles one or more of the other electrodes. Furthermore, in one embodiment, the capacitive sensing pixels may be interleaved such that at least one row and column of sensing pixels has an edge overlapping with an edge of an adjacent row or column of sensing pixels.

InFIG. 1, the input device100is 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 objects140in a sensing region120. Example input objects include fingers and styli, as shown inFIG. 1.

The input device100may utilize any combination of sensor components and sensing technologies to detect user input in the sensing region120. The input device100comprises one or more sensing elements121for detecting user input. As several non-limiting examples, the input device100may use capacitive, elastive, resistive, inductive, magnetic, acoustic, ultrasonic, and/or optical techniques.

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.

In some resistive implementations of the input device100, a flexible and conductive first layer is separated by one or more spacer elements from a conductive second layer. During operation, one or more voltage gradients are created across the layers. Pressing the flexible first layer may deflect it sufficiently to create electrical contact between the layers, resulting in voltage outputs reflective of the point(s) of contact between the layers. These voltage outputs may be used to determine positional information.

Some capacitive implementations utilize arrays or other regular or irregular patterns of capacitive sensing elements121to create electric fields. In some capacitive implementations, separate sensing elements121may be ohmically shorted together to form larger sensor electrodes. Some capacitive implementations utilize resistive sheets, which may be uniformly resistive. Although not shown, the sensing elements121may be capacitive sensing pixels that include one or more sensor or other electrodes.

Some capacitive implementations utilize “mutual capacitance” (or “transcapacitance”) sensing methods based on changes in the capacitive coupling between sensor electrodes. The change in capacitive coupling may be between sensor electrodes in two different sensing elements121or between two different sensor electrodes in the same sensing element121. 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 transcapacitance sensing method operates by detecting the capacitive coupling between one or more transmitter sensor electrodes (also “transmitter electrodes”) and one or more receiver sensor electrodes (also “receiver electrodes”). 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, and/or to one or more sources of environmental interference (e.g. other electromagnetic signals). Sensor electrodes may be dedicated transmitter electrodes or receiver electrodes, or may be configured to both transmit and receive.

InFIG. 1, a processing system110is shown as part of the input device100. The processing system110is configured to operate the hardware of the input device100to detect input in the sensing region120. The processing system110comprises parts of or all of one or more integrated circuits (ICs) and/or other circuitry components. (For example, a processing system for a mutual capacitance sensor device may comprise transmitter circuitry configured to transmit signals with transmitter sensor electrodes, and/or receiver circuitry configured to receive signals with receiver sensor electrodes). In some embodiments, the processing system110also comprises electronically-readable instructions, such as firmware code, software code, and/or the like. In some embodiments, components composing the processing system110are located together, such as near sensing element(s)121of the input device100. In other embodiments, components of processing system110are physically separate with one or more components close to sensing element(s) of input device100, and one or more components elsewhere. For example, the input device100may be a peripheral coupled to a desktop computer, and the processing system110may 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 device100may be physically integrated in a phone, and the processing system110may comprise circuits and firmware that are part of a main processor of the phone. In some embodiments, the processing system110is dedicated to implementing the input device100. In other embodiments, the processing system110also performs other functions, such as operating display screens, driving haptic actuators, etc.

For example, in some embodiments, the processing system110operates the sensing element(s) of the input device100to produce electrical signals indicative of input (or lack of input) in the sensing region120. The processing system110may perform any appropriate amount of processing on the electrical signals in producing the information provided to the electronic system. For example, the processing system110may digitize analog electrical signals obtained from the sensor electrodes. As another example, the processing system110may perform filtering or other signal conditioning. As yet another example, the processing system110may 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 system110may determine positional information, recognize inputs as commands, recognize handwriting, and the like.

FIG. 2shows a portion of an exemplary pattern of capacitive sensing pixels205(also referred to herein as capacitive pixels or sensing pixels) configured to sense in the sensing region120associated with a pattern, according to some embodiments. Each capacitive pixel205may include one of more of the sensing elements described above. For clarity of illustration and description,FIG. 2presents the regions of the capacitive pixels205in a pattern of simple rectangles and does not show various other components within the capacitive pixels205. In one embodiment, the capacitive sensing pixels205are areas of localized capacitance (capacitive coupling). Capacitive pixels205may be formed between an individual sensor electrode and ground in a first mode of operation and between groups of sensor electrodes used as transmitter and receiver electrodes in a second mode of operation. The capacitive coupling changes with the proximity and motion of input objects in the sensing region120associated with the capacitive pixels205, and thus may be used as an indicator of the presence of the input object in the sensing region120of the input device.

The exemplary pattern comprises an array of capacitive sensing pixels205X,Y(referred collectively as pixels205) arranged in X columns and Y rows, wherein X and Y are positive integers, although one of X and Y may be zero. It is contemplated that the pattern of sensing pixels205may comprises a plurality of sensing pixels205having other configurations, such as polar arrays, repeating patterns, non-repeating patterns, non-uniform arrays a single row or column, or other suitable arrangement. Further, as will be discussed in more detail below, the sensor electrodes in the sensing pixels205may be any shape such as circular, rectangular, diamond, star, square, nonconvex, convex, nonconcave concave, etc. As shown here, the sensing pixels205are coupled to the processing system110and utilized to determine the presence (or lack thereof) of an input object in the sensing region120.

In a first mode of operation, at least one sensor electrode within the capacitive sensing pixels205may be utilized to detect the presence of an input object via absolute sensing techniques. A sensor module204in processing system110is configured to drive a sensor electrode in each pixel205with a modulated signal and measure a capacitance between the sensor electrode and the input object (e.g., free space or earth ground) based on the modulated signal, which is utilized by the processing system110or other processor to determine the position of the input object.

The various electrodes of capacitive pixels205are typically ohmically isolated from the electrodes of other capacitive pixels205. Additionally, where a pixel205includes multiple electrodes, there electrodes may be ohmically isolated from each other. That is, one or more insulators separate the sensor electrodes and prevent them from electrically shorting to each other.

In a second mode of operation, sensor electrodes in the capacitive pixels205are utilized to detect the presence of an input object via transcapacitance sensing techniques. That is, processing system110may drive at least one sensor electrode in a pixel205with a transmitter signal and receive resulting signals using one or more of the other sensor electrodes in the pixel205, where a resulting signal comprising effects corresponding to the transmitter signal. The resulting signal is utilized by the processing system110or other processor to determine the position of the input object.

The input device100may be configured to operate in any one of the modes described above. The input device100may also be configured to switch between any two or more of the modes described above.

In some embodiments, the capacitive pixels205are “scanned” to determine these capacitive couplings. That is, in one embodiment, one or more of the sensor electrodes are driven to transmit transmitter signals. Transmitters may be operated such that one transmitter electrode transmits at one time, or multiple transmitter electrodes transmit at the same time. Where multiple transmitter electrodes transmit simultaneously, the multiple transmitter electrodes may transmit the same transmitter signal and effectively produce an effectively larger transmitter electrode. Alternatively, the multiple transmitter electrodes may transmit different transmitter signals. For example, multiple transmitter electrodes may transmit different transmitter signals according to one or more coding schemes that enable their combined effects on the resulting signals of receiver electrodes to be independently determined.

The sensor electrodes configured as receiver sensor electrodes may be operated singly or multiply to acquire resulting signals. The resulting signals may be used to determine measurements of the capacitive couplings at the capacitive pixels205.

In other embodiments, “scanning” pixels205to determine these capacitive coupling includes driving with a modulated signal and measuring the absolute capacitance of one or more of the sensor electrodes. In another embodiment, the sensor electrodes may be operated such that the modulated signal is driven on a sensor electrode in multiple capacitive pixels205at the same time. In such embodiments, an absolute capacitive measurement may be obtained from each of the one or more pixels205simultaneously. In one embodiment, the input device100simultaneously drives a sensor electrode in a plurality of capacitive pixels205and measures an absolute capacitive measurement for each of the pixels205in the same sensing cycle. In various embodiments, processing system110may configured to selectively drive and receive with a portion of sensor electrodes. For example, the sensor electrodes may be selected based on, but not limited to, an application running on the host processor, a status of the input device, an operating mode of the sensing device and a determined location of an input device.

A set of measurements from the capacitive pixels205form a “capacitive image” (also “capacitive frame”) representative of the capacitive couplings at the pixels205. 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.

In some embodiments, one or more of the sensor electrodes in the capacitive pixels205include one or more display electrodes used in updating the display of the display screen. In one or more embodiment, the display electrodes comprise one or more segments of a Vcom electrode (common electrodes), a source drive line, gate line, an anode electrode or cathode electrode, or any other display element. These display electrodes may be disposed on an appropriate display screen substrate. For example, the common electrodes may be disposed on the a transparent substrate (a glass substrate, TFT glass, or any other transparent material) in some display screens (e.g., In Plane Switching (IPS) or Plane to Line Switching (PLS) Organic Light Emitting Diode (OLED)), on the bottom of the color filter glass of some display screens (e.g., Patterned Vertical Alignment (PVA) or Multi-domain Vertical Alignment (MVA)), over an emissive layer (OLED), etc. In such embodiments, the common electrode can also be referred to as a “combination electrode”, since it performs multiple functions. In various embodiments, each of the sensor electrodes comprises one or more common electrodes. In other embodiments, at least two sensor electrodes may share at least one common electrode.

Continuing to refer toFIG. 2, the processing system110coupled to the sensing electrodes includes a sensor module204and optionally, a display driver module208. In one embodiment the sensor module comprises circuitry configured to drive a transmitter signal or a modulated signal onto and receive resulting signals with the resulting signals the sensing electrodes during periods in which input sensing is desired. In one embodiment the sensor module204includes a transmitter module including circuitry configured to drive a transmitter signal onto the sensing electrodes during periods in which input sensing is desired. The transmitter signal is generally modulated and contains one or more bursts over a period of time allocated for input sensing. The transmitter signal may have an amplitude, frequency and voltage which may be changed to obtain more robust location information of the input object in the sensing region. The modulated signal used in absolute capacitive sensing may be the same or different from the transmitter signal used in transcapacitance sensing. The sensor module204may be selectively coupled to one or more of the sensor electrodes in the capacitive pixels205. For example, the sensor module204may be coupled to selected portions of the sensor electrodes and operate in either an absolute or transcapacitance sensing mode. In another example, the sensor module204may be coupled to a different sensor electrodes when operating in the absolute sensing mode than when operating in the transcapacitance sensing mode.

In various embodiments the sensor module204may comprise a receiver module that includes circuitry configured to receive a resulting signal with the sensing electrodes comprising effects corresponding to the transmitter signal during periods in which input sensing is desired. In one or more embodiments, the receiver module is configured to drive a modulated signal onto a first sensor electrode in one of the pixels205and receive a resulting signal corresponding to the modulated signal to determine changes in absolute capacitance of the sensor electrode. The receiver module may determine a position of the input object in the sensing region120or may provide a signal including information indicative of the resulting signal to another module or processor, for example, a determination module or a processor of the electronic device (i.e., a host processor), for determining the position of the input object in the sensing region120. In one or more embodiments, the receiver module comprises a plurality of receivers, where each receiver may be an analog front ends (AFEs).

In one or more embodiments, capacitive sensing (or input sensing) and display updating may occur during at least partially overlapping periods. For example, as a common electrode is driven for display updating, the common electrode (or another sensor electrode in a separate region not being used to update the display) may also be driven for capacitive sensing. Or overlapping capacitive sensing and display updating may include modulating the reference voltage(s) of the display device and/or modulating at least one display electrode for a display in a time period that at least partially overlaps with when the sensor electrodes are configured for capacitive sensing. In another embodiment, capacitive sensing and display updating may occur during non-overlapping periods, also referred to as non-display update periods. In various embodiments, the non-display update periods may occur between display line update periods for two display lines of a display frame and may be at least as long in time as the display update period. In such embodiment, the non-display update period may be referred to as a long horizontal blanking period, long h-blanking period or a distributed blanking period. In other embodiments, the non-display update period may comprise horizontal blanking periods and vertical blanking periods. Processing system110may be configured to drive sensor electrodes120for capacitive sensing during any one or more of or any combination of the different non-display update times.

The display driver module208includes circuitry confirmed to provide display image update information to the display of the display device160during display updating periods. The display driver module208may be included with or separate from the sensor module204. In one embodiment, the processing system comprises a first integrated controller comprising the display driver module208and at least a portion of the sensor module204(i.e., transmitter module and/or receiver module). In another embodiment, the processing system comprises a first integrated controller comprising the display driver208and a second integrated controller comprising the sensor module204. In yet another embodiment, the processing system comprises a first integrated controller comprising a display driver module208and one of a transmitter module or a receiver module and a second integrated controller comprising the other one of the transmitter module and receiver module.

FIG. 3illustrates an array of sensor electrodes, according to one embodiment described herein. As stated above, the capacitive sensing pixels205are respective portions of a capacitive sensing region that include one or more sensor electrodes.FIG. 3illustrates one example arrangement of the various electrodes contained within a capacitive sensing pixel205. In input device100, the various electrodes forming the capacitive pixels205are disposed along the same plane. For instance, the electrodes305,310, and315may be disposed on the same substrate within the input device. In another embodiment, the sensor electrodes305,310, and/or315may be on different planes. For example, sensor electrode305may be on a first plane while sensor electrode310is on a second plane (e.g., two different layers of a stack or two different sides of a common substrate). In this example, the insulating spacer325may be omitted because the electrodes305,310are insulated by a vertical spacer e.g., a dielectric substrate that separates the two sensor electrodes305,310. Furthermore, if sensor electrode305is disposed on a layer above sensor electrode310, electrode310may have a middle cutout region that is smaller than sensor electrode305(i.e., sensor electrode305at least partially overlaps sensor electrode310). In another example, if sensor electrode315is disposed on a separate layer than sensor electrodes305and310, electrode315may have cutout regions that are smaller than sensor electrode310or sensor electrode305. That is, sensor electrode310may at least partially overlap sensor electrode315, and if the cutout region is further shrunk, sensor electrode305may also at least partially overlaps sensor electrode315. In one embodiment, sensor electrode315may be a single electrode sheet that is overlapped by the sensor electrodes305and310which are disposed on a separate layer. In another embodiment, each sensor electrode305,310, and315may be on separate layers when sensor electrodes310do not include any respective middle cutout regions and sensor electrode315also does not have cutout regions (i.e., is a single electrode sheet).

At least one of the electrodes in the pixels205encircles or partially encircles another electrode (e.g., surrounds an electrode on at least two sides). As shown, sensor electrode310completely surrounds sensor electrode305while sensor electrode315completely surrounds both sensor electrodes305and310. The sensor module204may include an independent connection330to each of the sensors electrodes305and310in each of the capacitive pixels205(for clarity, only the connections330A-C to capacitive sensing pixel2051,2are shown). In one embodiment, the sensor electrodes305and310may be concentric but this is not a requirement. Moreover, although electrode315is shown here as a single electrode, in other embodiments, this electrode315may include a plurality of different segments that are driven in the same manner. If so, the sensor module204may have respective connections to one or more of these segments in order to control at least a portion of the sensor electrode315during capacitive sensing. Furthermore, in device100, the capacitive pixels205include two sensor electrodes305and310(and part of sensor electrode315) but the present disclosure is not limited to such. In other embodiments, the pixels205may include additional sensor electrodes that may completely encircles, or partially encircles, one of the sensor electrodes305,310(e.g., another concentric right). In one embodiment, the shape of the sensor electrodes305,310is determined based on an area of the sensor electrode and the spatial interpolation of the response from this electrode. Moreover, the optical properties of the sensor electrode may be considered when the electrode is integrated into a display device. For example, the boundaries of the sensor electrodes305,310may be aligned with the boundaries of the display pixels.

Moreover, the processing system110may include a display driver module (not shown) that is independently connected to the various electrodes305,310, and315to drive signals onto the electrodes for updating a display. In one embodiment, the display driver module may use the same connections330to the sensor electrodes305,310,315used by the sensor module204—e.g., the connections330are multiplexed—but this is not a requirement.

Because the sensor electrodes305,310, and315may be located on the same plane, the capacitive pixel205includes dielectric spacers320and325that ohmically insulate adjacent electrodes. That is, dielectric spacer320electrically insulates sensor electrodes310and315while spacer325insulates sensor electrodes305and310. The dielectric spacers320and325may be formed from an insulative material deposited onto a substrate (e.g., silicon dioxide) or may be an air-gap in the substrate.

Using the sensor electrodes305,310, and315, the processing system110can perform different capacitive techniques—e.g., absolute capacitive sensing or transcapacitance sensing—using the same electrode layout. As will be explained in greater detail below, the sensor electrodes305,310, and315, however, may be used differently depending on the capacitive sensing technique currently being employed. For example, the sensor electrodes305,310, and315used to carry a sensing signal or a shielding signal may vary depending on the sensing technique used. In one embodiment, the shielding signal is modulated to form a guarding signal. Furthermore, these same electrodes may also be used for updating a display (e.g., the sensor electrodes305,310, and315may be used to generate a Vcom layer).

As discussed above, the sensor electrodes305,310, and315may be formed as discrete geometric forms, polygons, bars, pads, lines or other shape, which are ohmically isolated from one another. The sensor electrodes305,310, and315may be electrically coupled through circuitry to form electrodes having larger plan area relative to a discrete one of the sensor electrodes305,310, and315. The sensor electrodes305,310, and315may be fabricated from opaque or non-opaque conductive materials. In embodiments wherein the sensor electrodes305,310, and315are utilized with a display device, it may be desirable to utilize non-opaque conductive materials for the sensor electrodes305,310, and315. In embodiments where the sensor electrodes305,310, and315are not utilized with a display device, it may be desirable to utilize opaque conductive materials having lower resistivity for the sensor electrodes305,310, and315to improve sensor performance. Materials suitable for fabricating the sensor electrodes305,310, and315include ITO, aluminum, silver, copper, metal-mesh, and conductive carbon materials, among others.

FIG. 4Aillustrates a capacitive pixel that may be used in the input device ofFIG. 1, according to one embodiment described herein. Specifically,FIG. 4Aillustrates a portion400of a sensing region that includes the capacitive sensing pixel205. The charts405,410, and415inFIGS. 4B-4Dillustrate different techniques for driving the sensor electrodes305,310, and315in the pixel205for performing capacitive sensing.

Chart405ofFIG. 4Billustrates various examples of driving the sensor electrodes305,310, and315when performing absolute sensing—i.e., measuring a change in capacitive between an electrode driven using the modulated signal and an input object. In Example A, the sensor module drives the modulated signal suitable for absolute capacitive sensing (referred to inFIG. 4as signal “ABS”) onto the center electrode305while a guarding signal is driven onto the sensor electrode310. In one embodiment, the guarding signal may be equal to the modulated signal ABS in at least one of amplitude, shape, phase and/or frequency. For example, the guarding signal may have the same shape and frequency as the modulated signal driven on sensor electrode305. Guarding can reduce the effect of coupling capacitances between electrodes in the input device that may increase noise and limit the ability of the input device to identify a location of an input object. The outer electrode315can either be driven with a substantially constant voltage (C.V.) (e.g., ground, etc.) or remain electrically floating. Example B is similar to Example A except that modulated signal ABS is driven on sensor electrode310while electrode305is guarded. In this example, the sensor module measures the change in capacitance between sensor electrode310and the input object.

In Examples C and D, instead of transmitting the guarding signal on either electrode305or310, these electrodes are left electrically floating. This may be advantageous when the coupling capacitances between sensor electrodes305and310are not large enough to affect performance.

Example F differs from the previous examples in that the modulated signal ABS is driven on both the sensor electrodes305and310. In one embodiment, the sensor module may use two independent connections to sensor electrodes305and310to drive the ABS signal onto the electrodes305and310in parallel. Alternatively, the portion400may include an additional electrical connection between the electrodes305and310that electrically connects the two sensor electrodes305and310. This electrical connection may provide an conductive path that bypasses the insulative spacer325that typically electrical insulates the two sensor electrodes305and310. The sensor module may activate a switch that controls this electrical connection so that whatever signal is driven on one of the sensor electrodes is driven onto the other. In this scenario, the sensor module may drive the modulated signal onto one of the sensor electrodes (e.g., electrode310) and rely on the electrical connection between the sensor electrodes to drive the modulated signal onto the other electrode (e.g., electrode305). Regardless how the modulated signal is transmitted to both sensor electrodes305,310, in Example F the two sensor electrodes305and310are effectively combined into a larger sensor electrode.

In one embodiment, absolute capacitance sensing may be further divided into two different modes: touch sensing and hover detection. As used herein, touch detecting is used to detect the presence of an input object at a distance from the sensitive region that is closer than a distance attributed to hovering the input device over the sensitive region. In some embodiments, when performing touch sensing using absolute capacitance sensing, it may be preferred to use a smaller electrode to conduct the modulated signal since this reduces that amount of noise that can couple into the system and, for example, cause the detection circuits in the sensor module from reaching their rail voltages. As such, the input device may be configured based on any one of Examples A-D since these embodiments use only one sensor electrode, rather than two, for conducting the modulated signal ABS. For example, the input device may be configured such that when performing absolute capacitive sensing in touch mode, the modulated signal is driven onto sensor electrode305while a guarding signal is driven on electrode310as shown in Example A. Of course, the final determination of which of the Examples A-D to use may depend on the particular implementation—e.g., size or shape of the sensor electrodes, coupling capacitances, voltages of the detection circuitry, and the like.

However, when performing absolute capacitance sensing in hover detection mode, the ability of the input device to detect an input object hovering over the portion400of the sensing region may be increased if a larger sensor electrode is used. As such, the input device may be preconfigured to either use the larger of the two sensor electrodes305and310to conduct the modulated signal or use the configuration shown in Example F where the sensor module drives the modulated signal onto both sensor electrodes305and310. In this manner, the sensor module can change how the various signals or voltages are applied to the sensor electrodes305,310, and315depending on the current sensing mode. That is, when performing touch sensing, the input device may drive the sensor electrodes305,310, and315as shown in Example C, but when performing hover detection, the input device may drive the sensor electrodes305,310, and315as shown in Example F.

Chart410ofFIG. 4Cillustrates various examples of performing transcapacitance sensing using the sensor electrodes305,310, and315shown in portion400. As stated above, transcapacitance sensing detects user interaction based on changes in the capacitive coupling between sensor electrodes. One of the sensor electrodes is driven using a transmitter signal while the sensor module measures a resulting signal on another sensor electrode. The sensor electrode that is driven using the transmitter signal is referred to as the transmitter electrode (shown as TX in Charts410and415) while the electrode used to measure the resulting signal is referred to as the receiver electrode (shown as RX in Charts410and415). In Examples G and H, sensor electrode305is the transmitter electrode while sensor electrode310is the receiver electrode, or vice versa. This means the sensor module drives the transmitter signal onto electrode305while measuring the resulting signal on electrode310, or vice versa. During this time, the sensor electrode315is either held at a constant voltage C.V. such as ground (as shown in Example G) or is electrically floated (as shown in Example H).

Examples I and J illustrate that in one embodiment the input device may measure the change of capacitance between sensor electrode305and315rather than electrodes305and310as shown in Examples G and H. That is, the sensor module drives the transmitter signal on sensor electrode305and measures the resulting signal using electrode315, or vice versa. Meanwhile, the sensor electrode310may be either floated (Example I) or held to a constant voltage C.V. (Example J). Examples K and L illustrate configurations where the input device measures the change of capacitance between sensor electrode310and315by driving the transmitter signal on electrode310and measuring the resulting signal of electrode315or vice versa. During this time, the sensor electrode305may be electrically floated or held to a constant voltage C.V.

Chart415ofFIG. 4Dillustrates performing absolute capacitive sensing and transcapacitance sensing simultaneously using the sensor electrodes within one or more capacitive pixels. In Example M, the sensor module drives the transmitter signal used for transcapacitance sensing onto sensor electrode305while driving the modulated signal ABS used for absolute capacitance sensing onto sensor electrode310. In addition to driving the modulated signal ABS, the sensor module also measures the resulting signal using the sensor electrode310. However, in another example not shown, the sensor electrode305could be used to drive the transmitter signal and be used to sense absolute capacitance simultaneously.

Using data processing techniques which will not be discussed here, the processing system is able to derive location data based on both absolute and transcapacitance sensing. Stated differently, the processing system separately identifies a change of capacitance between the sensor electrode310and the input object via the modulated signal ABS as well as a change of capacitance between the two sensor electrodes305and310based on the transmitter and resulting signals. To produce such a mixed capacitance, some or all transmitting and receiving sensor electrodes may be electrically modulated relative to each other and to system ground. This approach works because a receiving sensor electrode modulated relative to system ground may detect absolute capacitance, and can detect transcapacitive coupling to any transmitting sensor electrode(s) modulated differently from system ground and from the receiving sensor electrode.

Some embodiments distinguish the separate absolute capacitance and transcapacitance portions. In that case, two or more measurements may be taken. For example, a first measurement may be taken with the receiving sensor electrode(s) modulated in a first way and the transmitting sensor electrode(s) modulated in a second way. The first and second way may be the same or different. Then, a second measurement may be taken with the receiving sensor electrode(s) kept at the first way of modulation and the transmitting sensor electrode(s) modulated in a third way (such that the modulation of the transmitter sensor electrode(s) relative to the receiver sensor electrode(s) is changed from the second way). This change in the transmitting sensor electrode modulation may be accomplished in a myriad of ways, including but not limited to the following: changing a voltage magnitude; changing the voltage phase; switching between binary ON/OFF voltages; flipping a sign of the voltage swing from positive to negative; changing the voltage swing to be higher or lower; etc. More than two measurements may be taken by some embodiments, such as to reduce noise or to better accommodate a more complex combination of transmitting sensor electrodes. Such a multi-measurement approach enables relatively straightforward estimation of the absolute capacitance and transcapacitance contributions.

In Example N, the modulated signal is driven, and the resulting signal is measured, using sensor electrode305while the transmitter signal is driven onto sensor module310. In both Examples M and N, sensor electrode315may either be held at a constant voltage or left electrically floating.

As shown by Examples A-N in charts405,410, and415, the input device can drive the same electrode layout in the pixel205in different ways depending on the capacitive technique used. That is, using the same electrode layout, the input device can use the electrodes in each capacitive pixel differently depending on the capacitive sensing technique. For example, while performing absolute capacitive sensing, the input device may drive a modulated signal onto a particular sensor electrode. However, when performing absolute and transcapacitance sensing simultaneously, the input device may ground that electrode. Furthermore, the sensor electrodes in the capacitive pixels may be driven differently depending on the mode of the sensing technique—e.g., whether the input device is performing touch sensing or hover detecting using absolute capacitive sensing. Thus, the same electrode layout can be used to perform multiple capacitive sensing techniques (or combination of these techniques) as well as different modes thereof.

In one embodiment, the absolute capacitive sensing (e.g., a first mode of capacitive sensing) and transcapacitive sensing (e.g., a second mode of capacitive sensing) may occur at times that do not overlap with updating a display in the input device. In another embodiment, however, the first and/or second mode of capacitive sensing may overlap, at least partially, in time with when the display is being updated—e.g., display signals are driven to update the pixels in the display.

FIG. 5illustrates a method500for driving sensor electrodes in a capacitive sensing pixel to enable two different capacitive sensing techniques, according to one embodiment described herein. At block505, the input device performs capacitive sensing using one or more sensor electrodes in a capacitive sensing pixel based on a first capacitive sensing technique. As used herein, a “capacitive sensing technique” includes using a single sensing technique or mode (e.g., driving the sensor electrodes in the capacitive pixels to perform hover detection based on absolute capacitive sensing) or using a combination of sensing techniques simultaneously (e.g., driving the sensor electrodes such that absolute and transcapacitance sensing is performed simultaneously).

At block510, the input device performs capacitive sensing using the same sensor electrodes but uses a second, different capacitive sensing technique. For example, during a first time period, the input device may drive the sensor electrodes in the pixels to perform touch sensing based on absolute capacitive sensing but during a second time period, the input device drives the sensor electrodes to perform transcapacitance sensing. Although method500illustrates using the same electrode layout for performing two different capacitive sensing techniques, the present disclosure may be used with any number of capacitive sensing techniques.

FIG. 6illustrates a staggered arrangement of capacitive sensing pixels, according to one embodiment described herein. Specifically,FIG. 6illustrates a portion600of a sensing region where the capacitive pixels205are arranged in a grid where the boundaries of one or both of the rows and columns do not form straight lines. In one embodiment, the processing system may execute an alignment post-processing calculation to compensate for the staggered relationship shown in portion600.

The pixels205in portion600may be spaced such that pixels205in adjacent columns overlap, but this is not a requirement. The pixels205in adjacent columns may overlap when any portion of the sensor electrodes305and310are directly between the sensor electrodes305and310in even or odd number columns. For instance, because some portion of the pixels205in column2is directly between the pixels305in columns1and3, the pixels205are deemed to overlap. Moreover, althoughFIG. 6illustrates staggering the pixels205in each row while the pixels remained aligned in the columns, the reverse is also possible or some mixture of both (i.e., the pixels in the rows and columns are staggered relative to each other).

Furthermore, the capacitive pixels205in different portions of the sensing region may be arranged using different patterns. For example, the pixels205in one half of the sensing region may be arranged in a grid pattern shown inFIG. 2while the pixels205in the other half of the sensing region is arranged in a pattern shown inFIG. 6. In this manner, the sensing region may be divided into any number of portions where each portion may have a different pixel205arrangement.

However, althoughFIGS. 2 and 6illustrate arranging the capacitive pixels205in a distinct pattern in the input device, this is not a requirement. Instead, the capacitive pixels205may be arranged with different spacings therebetween so that no pattern is formed.

FIGS. 7A-7Dillustrate various shapes of capacitive sensing pixels, according to one embodiment described herein. Specifically,FIGS. 7A-7Dillustrate alternative shapes of the sensor electrodes in the capacitive pixels205shown inFIGS. 3 and 4.FIG. 7Aillustrates a star-shaped capacitive pixel700that includes an inner sensor electrode705A that is electrically insulated from an outer sensor electrode715A via a spacer region710A where the outer electrode715A circumscribes the inner electrode705A. Although five points are shown, the star-shape may include any number of points.

FIG. 7Billustrates a quadrilateral capacitive pixel720. Specifically,FIG. 7Billustrates a rhombus-shaped quadrilateral as the capacitive pixel720. The lengths of the sides (e.g., the width dimension (W) may be less than or greater than the height dimension (H)) as well as the angle of the slant forming the quadrilateral may vary. Regardless, the outer electrode715A circumscribes that inner electrode705A.

FIG. 7Cillustrates a cross-shaped capacitive pixel725with a plurality of extensions. The extensions may either all be the same length as shown, or may be of various lengths. Additionally, the pixel725may include more or less than the number of extensions shown. Regardless of the shape or number of the extensions, the outer electrode715C circumscribes the inner electrode705C. Furthermore, the pixel725may be rotated in any desired manner within the array of sensor electrodes.

FIG. 7Dillustrates a circular or oval shaped capacitive pixel730where the outer electrode715D circumscribes the inner electrode705D. As shown here, one or more of the electrodes705D and715D (or a portions thereof) may be curved. In one embodiment, the curved shape shown in pixel730may be added to the pixels shown inFIGS. 7A-7C. For example, the electrodes705and710may have one side that is straight and another side that is curved. These curved edges may convex, concave, or some mixture of both (e.g., s-shaped). Furthermore, any of the embodiments shown inFIGS. 7A-Dcan be combined in any way to form different shaped capacitive pixels.

In one embodiment, the one or more of the sensor electrodes705A-D and715A-D are used as the sensor electrodes305and310shown inFIG. 4. As such, sensor electrodes705A-D and715A-D may be driven in any manner as shown by charts405,410, and415. Moreover, although the grid electrode315is not shown inFIGS. 7A-7D, the capacitive sensing pixels in these figures may include portions of a grid electrode that extends throughout the sensing region between capacitive pixels. Moreover, the present disclosure is not limited to the shapes shown inFIGS. 7A-7D. Indeed, any electrode shape that permits an input device to use the same electrode layout to perform capacitive sensing using different sensing techniques are within the scope of this disclosure. For example, in one embodiment, the outer electrodes715may have a different shape than the inner electrode705. For example, the interface between the inner electrode705and outer electrode715may include one shape (e.g., star, quadrilateral, cross-shaped, oval, etc.) while the interface between the outer electrode715and a grid electrode may have a different shape. For instance, usingFIG. 7Aas an example, the inner electrode705A and outer electrode715A interface at the spacer region710A to form a star shape. However, instead of the outer electrode715A forming a second star shaped interface with a surrounding grid electrode, it could have an oval or a square shaped interface.

FIG. 8illustrates capacitive sensing pixels805that are interleaved, according to one embodiment described herein. Specifically,FIG. 8illustrates a portion800of a sensing region where the boundaries of the capacitive sensing pixels805are interleaved. In some embodiments, detecting an input object is difficult if an input object interacts with only one capacitive sensing pixel. For example, a stylus contacting the middle of a sensor electrode of a capacitive pixel may not substantially affect the capacitance values associates with sensor electrodes in other capacitive pixels which may make the position of the stylus difficult to determine. By interleaving the boundaries or edges of adjacent capacitive pixels, the likelihood that an input object will affect the capacitance values associated with only one capacitive pixel is decreased or eliminated. State differently, the pixels may interleaved so that regardless of the position of an input object over a sensor electrodes, a sensor electrode in a neighboring capacitive pixel is affected by change of capacitance associated with the input object.

As shown here, the boundaries of adjacent capacitive sensing pixels805are interleaved such that at least a portion of each pixel805(e.g., an extension807) is partially enclosed or surrounded by the boundary of another pixel805. Stated differently, the pixels805may have boundaries that extend into adjacent rows and columns such that the edges of the adjacent pixels805overlap. Thus, regardless of where an input device is located within a pixel, interleaving the pixels805may reduce the maximum distance from the input device to a neighboring pixel805relative to an embodiment where the pixels are not interleaved. The pixels805may include any number of extensions807which may have any shape or size. For example, instead of one extension807, pixel805B may have two extensions807that are partially surrounded by the boundaries of pixel805A. Furthermore, the extensions may have various sizes—e.g., one extension of pixel805B into pixel805A may be larger than the other—and shapes. For example, the pixels805may be star shaped where the extensions807come to a point.

A portion850of the pixels805is enlarged to illustrate in detail the boundary between adjacent capacitive sensing pixels805. The dotted line801represents the boundary between the two adjacent pixels805. The pixel805D includes a first sensor electrode810A where at least a portion is partially surrounded by electrodes of the adjacent pixel805C. Pixel805D also includes a spacer region830that separates the first sensor electrode810A from a second sensor electrode815A. These electrodes may be used as, for example, sensor electrodes305and310shown inFIG. 4, and thus, may be driven in any manner shown in charts405,410, and415.

The pixels805C and805D are separated electrically by another spacer region825(if disposed on the same plane). Thus, in this embodiment, the pixels may not include a third sensor electrode (e.g., electrode315ofFIG. 3) that runs throughout the pixels805. Like pixel805D, the capacitive pixel805C includes sensor electrode815B that is separated from sensor electrode810B by spacer region820. The sensor electrodes810B and815B may correspond to sensor electrodes305and310shown inFIG. 4and may be driven in any manner shown in charts405,410, and415. As discussed above, by extending some portion of the sensor electrodes (e.g., electrodes810A and815A) such that they are at least partially surrounded by electrodes in a neighboring pixel (e.g., electrodes810B and815B), the input device has a decreased likelihood that an input object affects the capacitance associated with one pixel805without also affecting the capacitance associated with a neighboring pixel805.

The enlarged portion850illustrates that both sensor electrodes810A and815A of pixel805D extend into pixel805C, but this is not a requirement. For example, only sensor electrode815A may be partially surrounded by the electrodes815B or810B or pixel805C. However, if so, it may be advantageous to drive the modulating signal (when performing absolute capacitance sensing) or measure the resulting signal (when performing transcapacitance sensing) on the sensor electrode that extends into the neighboring pixel—e.g., sensor electrode815A—to increase the chance the change of capacitance associated with the sensor electrode is affected by the input object. Thus, if electrode815A extends into pixel805C but sensor electrode810A does not, the input device may be configured to drive the modulated signal onto electrode810A while electrode815A is used to, e.g., conduct a guarding signal or be left electrically floating.

In one embodiment, two of the sensor electrodes810may be on different layers (e.g., on two separate layers or on opposite sides of a common substrate). In this case, the extension may overlap in a vertical direction with another electrode. For example, sensor electrode805A may be on a top layer of a substrate while sensor electrode805B is disposed on a bottom layer of the same substrate. The extension807of sensor electrode805B may be, at least partially, covered by the sensor electrode805A such that some portion of extension807is directly below sensor electrode805A. The opposite is also true where some portion of extension807covers a portion of the sensor electrode805A assuming sensor electrode805B is disposed on a plane above a plane that includes the sensor electrode805A.

FIG. 9illustrates interleaved capacitive sensing pixels905, according to one embodiment described herein. Specifically,FIG. 9illustrates a portion900of a sensing region where capacitive sensing pixels905include at least two extensions907that extend into neighboring pixels905. For instance, pixel905B includes a first extension907A and a second extension907B that extend into neighboring pixels905A. The first extension907is surrounded on two sides by pixel905A while the second extension907B is surrounded on three sides. Moreover,FIG. 9illustrates that an extension907may be surrounded by multiple pixels. For example, extension907C borders both pixel905A and pixel905C. Thus, a single extension907may be interleaved with multiple capacitive sensing pixels.

FIGS. 8 and 9are intended to illustrate the principle of interleaving capacitive pixels generally. As such, the present disclosure is not intended to be limited to these illustrated examples. Any electrode extension907of a capacitive sensing pixel that performs the capacitive sensing techniques described herein is within the scope of this disclosure.

The embodiments and examples set forth herein were presented in order to best explain the present technology and its particular application and to thereby enable those skilled in the art to make and use the present technology. 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 present technology to the precise form disclosed. While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.