KR20200146032A - Modulating a reference voltage to perform capacitive sensing - Google Patents

Abstract

The present disclosure generally provides an input device having a reference voltage modulator that modulates reference voltage rails when performing capacitive sensing. In one embodiment, the reference voltage rails are coupled to a DC power source which provides power for operating a panel including a display screen integrated with a touch sensing region. Before performing capacitive sensing, the input device may isolate the DC power source from the reference voltage rails and use the reference voltage rails to modulate rails (e.g., V_(DD) and V_(GND)). The input device may include a receiver that simultaneously acquires resulting signals from a plurality of display and/or sensor electrodes when modulating the reference voltage rails. The resulting signals may be then processed to determine if an input object is interacting with the input device.

Description

Modulation of the reference voltage to perform capacitive sensing {MODULATING A REFERENCE VOLTAGE TO PERFORM CAPACITIVE SENSING}

Embodiments of the present invention relate generally to electronic devices and, more particularly, to modulating reference voltages to perform capacitive sensing.

Input devices including proximity sensor devices (also commonly referred to as touchpads or touch sensor devices) are widely used in various electronic systems. A proximity sensor device generally includes a sensing region, often bounded by a surface, in which the proximity sensor device determines the presence, location and/or motion of one or more input objects. Proximity sensor devices may be used to provide interfaces to the electronic system. For example, proximity sensor devices are often used as input devices for large computing systems (such as opaque touchpads integrated into or incidental to laptop or desktop computers). Proximity sensor devices are also often used in small computing systems (such as touch screens integrated into cellular phones).

One embodiment described herein includes an input device that includes a plurality of sensor electrodes and a processing system. The processing system includes: a sensor module configured to operate a plurality of sensor electrodes for capacitive sensing; A reference voltage modulator configured to modulate the reference voltage rails of the processing system; And a receiver configured to simultaneously capture result signals from the sensor electrodes to detect the input object while modulating the reference voltage rails.

Another embodiment described herein includes a processing system comprising a sensor module configured to drive a plurality of sensor electrodes for capacitive sensing and a reference voltage modulator configured to modulate reference voltage rails of the processing system, wherein the voltage rail Prior to modulating them, the processing system is configured to electrically short the reference voltage rails from the at least one DC power supply. The processing system also includes a receiver configured to capture the resulting signals using the sensor electrodes to detect the input object while modulating the voltage rails.

Another embodiment described herein comprises an input device comprising a plurality of sensor electrodes, each sensor electrode comprising at least one common electrode of the display device, wherein the sensor electrodes are on a common plane in a matrix arrangement. Is placed. The input device includes a sensor module configured to operate a plurality of sensor electrodes for capacitive sensing; A reference voltage modulator configured to modulate the reference voltage rails of the processing system; And a processing system including a receiver configured to capture result signals using the sensor electrodes to detect the input object while modulating the voltage rails.

Another embodiment described herein includes driving a capacitive sensing signal on a plurality of sensor electrodes in an input device; And electrically shorting the reference voltage rails from at least one DC power source. After electrically shorting the reference voltage rails, the method includes modulating the reference voltage rails. The method includes capturing resulting signals using sensor electrodes to detect an input object while modulating the voltage rails.

In order that the features of the present invention mentioned above may be understood in detail, a more detailed description of the present disclosure briefly summarized above may be made with reference to embodiments, and some of the embodiments are illustrated in the accompanying drawings. However, it should be noted that the appended drawings illustrate only certain typical embodiments of the present disclosure, and therefore, as this disclosure may be accepted for other equally effective embodiments, should not be regarded as a limitation of its scope. do.
1 is a block diagram of an exemplary system including an input device, in accordance with embodiments of the present invention.
2 is an input device modulating reference voltage rails for performing capacitive sensing, in accordance with an embodiment described herein.
3 is an input device that modulates reference voltage rails for performing capacitive sensing, according to an embodiment described herein.
4 is an input device for modulating reference voltage rails for performing capacitive sensing, according to an embodiment described herein.
5 is a circuit diagram of a reference voltage modulator, according to an embodiment described herein.
6 is a flow diagram of waking up an input device from a low power state using modulated reference voltage rails, according to an embodiment described herein.
7 illustrates an exemplary electrode arrangement for performing capacitive sensing, according to an embodiment described herein.
8 is an input device for detecting a noise signal or a communication signal from an active input object, according to an embodiment described herein.
9 is a circuit diagram of a receiver for capturing resulting signals to identify a noise or communication signal, according to an embodiment described herein.
10 is a flow diagram for identifying a noise or communication signal using capacitive sensing, according to an embodiment described herein.
11 illustrates various capacitances between an input device and an environment, according to an embodiment described herein.
12 is an input device that modulates reference voltage rails for performing capacitive sensing, according to an embodiment described herein.
13 is a flow chart for mitigating the effects of a low ground mass condition, according to an embodiment described herein.
14 illustrates various capacitances between an input device and an environment, according to an embodiment described herein
15 is a chart showing results of mitigating the effects of a low ground mass condition, according to an embodiment described herein.

For ease of understanding, the same reference numerals have been used, where possible, to indicate the same elements common to the drawings. It is intended that elements disclosed in one embodiment may be beneficially used without specific citation on other embodiments. The drawings referred to herein are not to be understood as being drawn to scale unless specifically stated. Also, the drawings are often simplified and details or elements are omitted for clarity of presentation and description. The drawings and description are provided to explain the principles described below, where like designations indicate like elements.

The following detailed description is merely exemplary in nature and is not intended to limit the present disclosure or its applications and uses. Moreover, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary, or the following detailed description.

Various embodiments of the present invention provide an input device comprising a reference voltage modulator that modulates reference voltage rails when performing capacitive sensing. In one embodiment, the reference voltage rails are coupled to a DC power source that provides power to operate a panel that includes a display screen integrated with a touch sensitive area. Prior to performing capacitive sensing, the input device may separate the DC power source from the reference voltage rails and use the reference voltage rails to modulate the rails-eg, V _DD and V _GND . For example, the reference voltage modulator may change the voltages on the rails by equal increments. That is, if the high reference rail (eg, V _DD ) increases by 1V, the reference voltage modulator also increases the low reference rail (eg, V _GND ) by 1V. In this example, the voltage difference between the reference voltage rails remains constant as the rails are modulated. As used herein, separating the reference voltage rails may not require physically shorting the rails from the power source. Instead, the reference voltage rails may be inductively or capacitively coupled to the power source.

In one embodiment, the reference voltage rails are modulated (and capacitive sensing is performed) when the input device is in a low power state. In one example, the display/sensing panel (and backlight, if applicable) is turned off and does not draw power. Nevertheless, by modulating the reference voltage rails, the sensor electrodes in the display and display/sensing panel can be used to perform capacitive sensing. In other words, by modulating the reference voltage rails, an input object (eg, a finger) capacitively coupled to sensor electrodes in the display and panel can be detected by measuring a change in capacitance. Once the input object is detected, the input device wakes up and switches from the low power state to the active state.

In one embodiment, when performing capacitive sensing by modulating the reference voltage rails, the display and sensor electrodes are treated as one capacitive pixel or electrode. As such, by measuring the resulting signals from the measurement display and sensor electrodes, the input device determines whether the input object is closest to the panel, but does not determine a specific location on the panel the input object is in contact with or hovering above. Does not. Instead, once in an active state, the input device may perform a granular type of capacitive sensing technique that identifies a specific location of the input object in the sensing region. When performing capacitive sensing in the active state, the input device may drive DC voltages onto the reference voltage rails-that is, either the rails are not modulated or the rails sense the current or charge required to do so. Without being modulated.

Referring now to the drawings, FIG. 1 is a block diagram of an exemplary input device 100, according to embodiments of the present invention. Input device 100 may be configured to provide input to an electronic system (not shown). As used herein, the term “electronic system” (or “electronic device”) broadly refers to any system capable of electronically processing information. Some non-limiting examples of electronic systems include personal computers of all sizes and types, such as desktop computers, laptop computers, netbook computers, tablets, web browsers, e-book readers, and personal data. Includes terminals (PDAs). Additional exemplary electronic systems include input device 100 and composite input devices, such as physical keyboards including separate joysticks or key switches. Additional exemplary electronic systems include peripherals, such as data input devices (including remote controls and mice), and data output devices (including display screens and printers). Other examples include remote terminals, kiosks, and video game appliances (eg, video game consoles, portable gaming devices, and the like). Other examples include communication devices (including cellular phones such as smartphones), and communication devices (recorders, editors, and players such as televisions, set-top boxes, music players, digital picture frames, and Media devices (including digital cameras). In addition, the electronic system can be a host or slave to the input device.

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

In FIG. 1, the input device 100 is a proximity sensor device (also often referred to as a “touchpad” or “touch sensor device”) configured to sense an input provided by one or more input objects 140 in the sensing area 120. (Referred to as). Exemplary input objects include fingers and stylus, as shown in FIG. 1.

Sensing area 120 is above, around, inside and/or over input device 100 where input device 100 can detect user input (e.g., user input provided by one or more input objects 140 ). Covers any nearby space. The sizes, shapes, and locations of specific sensing regions may vary greatly from embodiment to embodiment. In some embodiments, the sensing area 120 extends into space in one or more directions from the surface of the input device 100 until signal-to-noise ratios prevent sufficiently accurate object detection. The distance that this sensing region 120 extends in a particular direction may, in various embodiments, be approximately less than millimeters, millimeters, centimeters, or more, depending on the type of sensing technology used and the desired accuracy. It may change. Accordingly, some embodiments provide contact with any surfaces of input device 100, contact with an input surface (eg, a touch surface) of input device 100, applied force or pressure, and/or Detects an input that does not include any contact with the input surface of the input device 100 coupled with some amount of the combination. In various embodiments, the input surfaces may be provided by the surfaces of the casings on which the sensor electrodes reside, by face sheets provided over the front of the sensor electrodes or any casings, and the like. In some embodiments, the sensing area 120 has a rectangular shape when projected onto the input surface of the input device 100.

Input device 100 may detect user input in sensing area 120 using any combination of sensor components and sensing technologies. Input device 100 includes one or more sensing elements for detecting user input. As several non-limiting examples, input device 100 may use capacitive, elastic, resistive, inductive, magnetic, acoustic, ultrasonic, and/or optical techniques.

Some implementations are configured to provide images covering spaces of 1, 2, 3, or higher dimensions. Some implementations are configured to provide projections of the input along certain axes or planes.

In some resistive implementations of input device 100, the flexible and conductive first layer is separated from the conductive second layer by one or more spacer elements. During operation, one or more voltage gradients are created across the layers. Pressing the flexible first layer may deflect the flexible first layer sufficiently to create electrical contact between the layers, resulting in voltage outputs that reflect the point(s) of contact between the layers. These voltage outputs may be used to determine location information.

In some inductive implementations of input device 100, one or more sensing elements capture loop currents induced by a resonating coil or pair of coils. Some combination of magnitude, phase, and frequency of the currents may then be used to determine the location information.

In some capacitive implementations of input device 100, a voltage or current is provided to generate the electric field. Adjacent input objects cause changes in the electric field, resulting in detectable changes in capacitive coupling, which may be detected as changes in voltage, current, or the like.

Some capacitive implementations use arrays of capacitive sensing elements or other regular or irregular patterns to generate electric fields. In some capacitive implementations, separate sensing elements are resistively shorted together to form larger sensor electrodes. Some capacitive implementations use resistive sheets, which may be uniformly resistive.

Some capacitive implementations use “magnetic capacitance” (or “absolute capacitance”) sensing methods based on changes in capacitive coupling between sensor electrodes and an input object. In various embodiments, the input object close to the sensor electrodes changes the electric field close to the sensor electrodes, thereby changing the measured capacitive coupling. In one implementation, the absolute capacitive sensing method operates by modulating the sensor electrodes with respect to a reference voltage (eg, system ground) and by detecting the capacitive coupling between the sensor electrodes and input objects.

Some capacitive implementations use “mutual capacitance” (or “transcapacitance”) sensing methods based on changes in capacitive coupling between sensor electrodes. In various embodiments, an input object close to the sensor electrodes changes the electric field between the sensor electrodes, thereby changing the measured capacitive coupling. In one implementation, a method of transcapacitance sensing includes one or more transmitter sensor electrodes (also “transmitter electrodes” or “transmitters”) and one or more receiver sensor electrodes (also “receiver electrodes” or “receivers”). ) Works by detecting the capacitive coupling between. Transmitter sensor electrodes may be modulated with respect to a reference voltage (eg, system ground) to transmit transmitter signals. Receiver sensor electrodes may be held substantially constant with respect to the reference voltage to facilitate reception of the resulting signals. The resulting signal may include influence(s) corresponding to one or more transmitter signals and/or to one or more sources of interference of the environment (eg, other electromagnetic signals). The sensor electrodes may be dedicated transmitters or receivers, or may be configured to both transmit and receive.

In FIG. 1, processing system 110 is shown as part of input device 100. The processing system 110 is configured to operate the hardware of the input device 100 to detect input in the sensing area 120. The processing system 110 includes portions or all of one or more integrated circuits (ICs) and/or other circuit components. For example, a processing system for a mutual capacitance sensor device may include a transmitter circuit configured to transmit signals by the transmitter sensor electrodes, and/or a receiver circuit configured to receive signals by the receiver sensor electrodes). In some embodiments, processing system 110 also includes electronic-readable instructions, such as firmware code, software code, and/or the like. In some embodiments, the components that make up the processing system 110 are located together, eg, in the vicinity of the sensing element(s) of the input device 100. In other embodiments, the components of the processing system 110 are physically separated from one or more components close to the sensing element(s) of the input device 100, and one or more components elsewhere. For example, input device 100 may be a peripheral coupled to a desktop computer, and processing system 110 may be a central processing unit of the desktop computer and one or more (possibly with associated firmware) separate from the central processing unit. It may also include software configured to run the ICs. As another example, input device 100 may be physically integrated into a phone, and processing system 110 may include circuits and firmware, which are part of the phone's main processor. In some embodiments, processing system 110 is dedicated to implementing input device 100. In other embodiments, the processing system 110 also performs other functions, such as operating display screens, driving haptic actuators, and the like.

Processing system 110 may be implemented as a set of modules that process different functions of processing system 110. Each module may include circuitry, firmware, software, or combinations thereof that are part of processing system 110. In various embodiments, different combinations of modules may be used. Exemplary modules include hardware operation modules that operate hardware such as sensor electrodes and display screens, data processing modules that process data such as sensor signals and location information, and reporting modules that report information. Additional exemplary modules include sensor operation modules configured to operate the sensing element(s) to detect input, identification modules configured to identify gestures such as mode change gestures, and mode change modules to change operation modes. Include.

In some embodiments, processing system 110 responds directly to user input (or lack of user input) in sensing region 120 by causing one or more actions. Exemplary actions include changing operating modes, as well as GUI actions such as cursor movement, selection, menu navigation, and other functions. In some embodiments, the processing system 110 is an input (or , Lack of input). In some embodiments, some portion of the electronic system is received from the processing system 110 to take an action according to user input, e. Process the information.

For example, in some embodiments, the processing system 110 may generate electrical signals indicative of an input (or lack of input) at the sensing region 120. Works. The processing system 110 may perform any suitable amount of processing on the electrical signals when generating information provided to the electronic system. For example, processing system 110 may digitize analog electrical signals obtained from sensor electrodes. As another example, processing system 110 may perform filtering or other signal conditioning. Further, as another example, processing system 110 may subtract or otherwise utilize the baseline so that the information reflects the difference between the electrical signals and the baseline. Also as additional examples, processing system 110 may determine location information, recognize inputs as instructions, recognize handwriting, and the like.

“Location information”, as used herein, broadly encompasses absolute position, relative position, velocity, acceleration, and other types of spatial information. Exemplary "zero-dimensional" location information includes near/far or contact/non-contact information. Exemplary “one-dimensional” location information includes locations along an axis. Exemplary “two-dimensional” location information includes motions in a plane. Exemplary “three-dimensional” location information includes instantaneous or average velocities in space. Additional examples include other representations of spatial information. Historical data relating to one or more types of location information may also be determined and/or stored, including, for example, historical data tracking position, motion, or instantaneous speed over time.

In some embodiments, input device 100 is implemented with additional input components operated by processing system 110 or by some other processing system. These additional input components may provide redundant functionality, or some other functionality for input into the sensing area 120. 1 shows buttons 130 close to sensing area 120 that may be used to facilitate selection of items using input device 100. Other types of additional input components include sliders, balls, wheels, switches, and the like. Conversely, in some embodiments, input device 100 may be implemented without any other input components.

In some embodiments, input device 100 includes a touch screen interface, and sensing area 120 overlaps at least a portion of an active area of the display screen. For example, input device 100 may include substantially transparent sensor electrodes overlying a display screen and may provide a touch screen interface to an associated electronic system. The display screen may be any kind of dynamic display capable of displaying a visual interface to the user, and any kind of light emitting diode (LED), organic LED (OLED), cathode ray tube (CRT), liquid crystal display (LCD), plasma, Electroluminescence (EL), or other display technologies may be included. Input device 100 and display screen may share physical elements. For example, some embodiments may use some of the same electrical components to display and sense. As another example, the display screen may be operated in part or as a whole by processing system 110.

While many of the embodiments of the invention are described in the context of a fully functional device, it should be understood that the mechanisms of the invention can be distributed in various types as a program product (eg, software). For example, the mechanisms of the present invention include information bearing media readable by electronic processors (e.g., non-transitory computer-readable and/or memorable/writable information carrier media readable by processing system 110). ) May be implemented and distributed as a software program. Moreover, the embodiments of the present invention apply equally regardless of the particular type of medium used to carry out the distribution. Examples of non-transitory electronically readable media include various discs, memory sticks, memory cards, memory modules, and the like. Electronic readable media may be based on flash, optical, magnetic, holographic, or any other storage technology.

2 is an input device 200 that modulates reference voltage rails for performing capacitive sensing, according to an embodiment described herein. The input device 200 includes a power supply 202, a host 204, a processing system 110, a backlight 232, and a display/sensing panel 234. In one embodiment, power supply 202 provides at least two reference voltages, i.e., V _DD and V _GND , that provide power to processing system 110, backlight 232, and display/sensing panel 234. It is an output DC power source. Power source 202 may be a power converter or battery plugged into an external power source (eg, an AC or DC electrical grid). As used herein, the low reference voltage (ie, V _GND ) is also referred to as the chassis ground 208 to indicate that it is the reference voltage for the input device 200. In contrast, other power domains at input device 200 may include local ground references (eg, local ground 216 ), which may be the same voltage as chassis ground 208 or a different voltage. For example, as described below, in some time periods, local ground 216 may be the same voltage as chassis ground 208, but is modulated by being induced to different voltages in other time periods.

In one embodiment, the host 204 is of the input device 200 that performs any number of functions, such as making calls, transmitting data wirelessly, running operating systems or applications, and so on. Represents a general system. Host 204 includes a display source 206 that provides updated data frames to processing system 110. For example, display source 206 may be a graphics processing unit (GPU) that transmits pixel or frame data to processing system 110 to update the display on display/sensing panel 234. To provide updated display data, the display source 206 couples to the processing system 110 via a high speed link 244 that may transmit data at a rate equal to or greater than 1 Gbit per second at a full frame rate. Ring. For example, display source 206 may communicate with display data over high speed link 244 using DisplayPort ^™ (eg, eDP) or MIPI® display interfaces. This interface may include a single pair (e.g., differential) or multiple wire physical connections-e.g. 3 wire signaling, multiple links by shared clock, embedded clock, 3 level signaling, etc. .

The processing system 110 includes switches 210 and 212, a timing controller 220, and a power management controller 230. Switches 210 and 212 selectively couple reference voltage rails 211A and 211B to power supply 202. Using the control signal 218, the timing controller 220 can electrically connect and short the reference voltage rails 211 to the power source 202 by opening and closing the switches 210 and 212. Although shown as a resistive connection, in other embodiments, reference voltage rails 211 may be capacitively or inductively coupled to power source 202. In any case, the switches 210 and 212 may be used to short the reference voltage rails 211 from the power supply 202 but the modulating signal 228 may be used to modulate the voltage rails.

When the switches 210 and 212 are closed, the power source 202 charges the bypass capacitor 214. When the switches 210, 212 are open, the charge stored on the bypass capacitor 214 is applied to various components in the power input device 200 (e.g., power management controller 230, backlight 232, or It can be used to feed reference voltage rails 211 which are then used to feed the panel 234. In one embodiment, timing controller 220 uses control signal 218 to control switches 210, 212 to maintain a substantially constant, average voltage across capacitor 214 and rails 211. You can also open and close periodically. Alternatively, a separate control element (e.g., a flyback inductor) may control the voltage across capacitor 214, while timing controller 220 uses signal 228 to control the reference voltage rails 211 ) Is modulated.

The timing controller 220 includes a sensor module 222, a display module 224, and a reference voltage modulator 226. The sensor module 222 is coupled to the display/sensing panel 234, and more specifically, may be coupled directly to the sensor electrodes 242 in the panel 234 or via a modulated signal 228. . Using the sensor electrodes 242, the sensor module 222 performs capacitive sensing in the sensing region 120 shown in FIG. 1, which may include the sensor electrodes 242. As described above, the sensor module 222 may use self-capacitance, mutual capacitance, or a combination of both to identify a specific location in the sensing area 120 that the input object is in contact with or hovering above. have.

The display module 224 includes a display circuit 236 (e.g., source drivers and gate selection logic) and display electrodes 240 (e.g., source electrodes, gate electrodes) to update the display in the panel 234. , Common electrodes). For example, based on the display data received from the display source 206, the display module 224 iterates through the rows of the display using gate electrodes and uses the source electrodes to repeat in that selected row. Update each of the display pixels. As such, the display module 224 may receive updated display frames from the host 204 and update (or refresh) individual pixels in the display/sensing panel 234 accordingly.

The reference voltage modulator 226 outputs a modulated signal 228 that modulates the reference voltage rails 211. In one embodiment, the reference voltage modulator 226 modulates the voltage rails 211 only when the rails 211 are shorted from the power source 202 (i.e., when the switches 210, 212 are open). do. Doing so causes the modulating signal 228 to modulate the reference voltage rails 211 for the power supply 202 outputs-ie, V _DD and V _GND . If the power supply 202 is not electrically shorted when the reference voltage rails 211 are modulated, V _DD and V _GND are different configurations in the input device 200 that depend on the power supplied by the power supply 202. The elements may be shorted by a modulated signal 228 that may cause them to behave unpredictably or improperly. For example, host 204 (or other components in input device 200 not shown) may also use power source 202 to power its components. Host 204 may be designed to operate with unmodulated power sources, so if modulated signal 228 is not electrically isolated from power source 202, signal 228 has a negative effect on host 204. May be crazy.

In one embodiment, the modulating signal 228 modulates the reference voltage rails by increasing or decreasing the voltages on these rails in a separate quantified or periodic manner. In one example, the modulating signal 228 causes the same or similar voltage change on both voltage rails 211A and 211B such that the voltage difference between the rails 211 remains substantially constant. For example, if V _DD is 4V and V _GND is 0V, the modulating signal is on both rails such that voltage rail 211A varies between 5V and 3V, but voltage rail 211B varies between -1V and 1V. You can also add a 1V voltage swing to the phase. Nevertheless, the voltage difference (ie, 4V) between the rails 211 remains the same. Moreover, the modulating signal 228 may be a periodic signal (eg, a sinusoidal or square wave), or a non-periodic signal in which no modulation is performed using a repetitive signal. In one embodiment, the capacitive sensing measurement is demodulated in a way that matches the modulated waveform of modulated signal 228.

By modulating the reference voltage rails 211 relative to the chassis ground, from the perspective of the processing system 110, it appears as if the external world and input objects coupled to the chassis have voltage signals that are modulating. That is, for a powered system in processing system 110, its voltage is stable and not coupled to any input object closest to panel 234 and modulated reference voltage rails 211. It appears that the rest of the world, including other components in the input device 200 not being modulated, is modulating. One advantage of modulating the reference voltage rails 211 is that all components coupled to the rails 211 are modulated by the modulating signal 228. Thus, a separate modulated signal need not be driven on the display electrodes 240, the display circuit 236, or the power management controller 230 to protect these electrodes from interfering with capacitive sensing. In other words, the voltage difference between the electrodes used to perform capacitive sensing and the various components in the display panel 234 does not change. Thus, even if the electrodes and components in panel 234 are capacitively coupled, this coupling capacitance affects the resulting signal generated on the electrodes. Moreover, standard components may be used-that is, the display circuit 236 and the power management controller 230 do not need to be modified to perform guarding.

Power management controller 230 (e.g., one or more power management integrated circuits (PMICs)) powers display circuit 236 and backlight 232 in display/sensing panel 234 via panel power sources 231 It provides several voltages for this. Power management controller 230 may include a plurality of different power sources supplying different voltages (eg, TFT gate voltages V _GH , VHL, source voltages, VCOM, etc.). To generate various voltages, the power supplies are applied by circuitry in the backlight 232 or panel 234 using inductive boost circuits or capacitive charge pumps to provide the DC voltage provided by the reference voltage rails 211. They may be switched power supplies that change to a desired DC voltage. Power supplies may also include buck circuits that efficiently feed low voltage digital circuits such as gigabit serial links.

In one embodiment, the reference voltage modulator 226 may modulate the voltage rails 211 when the input device 200 is in a low-power state. In a mobile device such as a smartphone with an LCD display, most of the power consumed by the display system is consumed by the backlight 232, the display module 224, and the display circuit 236. In one example, the backlight 232, when on, draws 1-3 W, while the display module 224 and display circuit 236 draws 0.5 to 1 W. In contrast, the sensor module 222 may draw 50-150 mW when performing capacitive sensing. Accordingly, when both the backlight 232 and the display module 224 are deactivated when in a low power state, power consumption can be greatly reduced. In one embodiment, the backlight 232 and display module 224 are not powered while the reference voltage rails 211 are modulated.

However, when the sensor and display modules 222, 224 are located on the same integrated circuit, the display control signals 233 are used to deactivate the display module 224 and the sensor module 222 and the sensor control signal It may still be impossible to perform capacitive sensing using s 235. In this example, the capacitive input device performed by the sensor module 222 to determine when to wake up from the low-power state (i.e., to determine when the user's finger approaches the panel 234). Relying on sensing, the display module 224 must also be active, which means that the input device 200 does not benefit from the power savings that deactivate the display module 224. In contrast, the input device 200 shown in FIG. 2 can perform capacitive sensing without a power supply box to the separated sensor module 222 when in a low power state, and thus, the sensor module 222 and the display It can benefit from power savings that can disable both module 224. Thus, in the low-power state, the sensor module 222, the display module 224, the power management controller 230, the backlight 232, and the display sensing circuit 236 can be deactivated, respectively.

To perform capacitive sensing in a low-power state when the sensor module 222 is deactivated, in one embodiment, the reference voltage modulator 226 results in modulating at least one of the voltage rails 211. And circuitry for capturing, from the sensor electrodes 240, 242, signals-that is, resulting signals. To do this, the reference voltage modulator 266 includes a separate receiver (not shown in Fig. 2) that measures the resulting signals. In addition, the reference voltage modulator 266 may have a filter (analog or digital) and other circuitry such as an analog-to-digital converter (ADC) for sampling the resulting signals. Based on measuring the changes in the coupling capacitance 246 between the input object 140 and the display/sensing panel 234, the input device 200 is the input object close to or in contact with the panel 234. Proximity can be detected. In one embodiment, the resulting signals are captured simultaneously from both display electrodes 240 and sensor electrodes 242. The display and sensor electrodes 240 and 242 may be coupled to the reference voltage rails 211 by the panel 234. For example, the display and sensor electrodes 240, 242 allow display updating to power (e.g., gate line voltage, Vcom voltage, source voltage) and power for capacitive sensing (e.g., individual sensor electrodes 242 A) to a power management controller 230 that provides voltages for feeding the receivers coupled to a). Eventually, the power management controller 230 receives its power through the reference voltage rails 211. Thus, the display and sensor electrodes 240, 242 (as well as other components in the panel 234) have an electrical node in common with the reference voltage modulator 226 (i.e., the modulating signal 228 is a voltage rail The same electrical node coupling to 211B). Thus, when modulating the reference voltages 211, it modulates the power supplies in the power management controller 230 and, consequently, various components in the panel 234-e.g., display and sensor electrodes 240, By modulating 242-makes the input device 200 measurable user inputs.

Since the reference voltage modulator 226 is also coupled to this common node, the modulator 226 will simultaneously capture the resulting signals from the display and sensor electrodes 240, 242 when modulating the reference voltage rails 211. May be. In other words, the reference voltage modulator 226 captures the combined resulting signals from all coupled electrodes in parallel, rather than individually capturing the resulting signals at different time periods from the various electrodes in the panel 234. Needs to be. By capturing the resulting signals simultaneously, panel 234 may be considered a single large capacitive pixel or electrode. As the input object approaches any part or location in the panel 234, the display and sensor electrodes 240, 242 at that part cause the capacitance (e.g., self-capacitance) caused by the proximity of the input object. Generates resulting signals indicating the change in. Thus, in one embodiment, by evaluating the resulting signals captured by the reference voltage modulator 226, the input device 200 can determine whether the input object is closest to the panel 234. However, since the panel is one capacitive electrode (instead of a plurality of discrete capacitive electrodes or pixels), the device 200 identifies a particular portion or location in the panel 234 where the input object is located. It may not be possible.

In one embodiment, instead of using both the display and sensor electrodes 240, 242 to perform capacitive sensing when modulating the reference voltage rails 211, the reference voltage modulator 226 is only used for the display electrodes 240 ) Or just capture the resulting signals from the sensor electrodes 242. As long as the electrodes coupled to the reference voltage modulator cover substantially the entire area of the panel 234, the input device 200 can detect the input object regardless of the specific location of the object in the panel 234. .

Once the input object is detected, the input device 200 may switch from the low power state to an active state where modulated signals are received during the display update time. For example, the input device 200 may activate the sensor module 222 to perform a different capacitive sensing technique. Unlike capacitive sensing performed using the reference voltage modulator 226, this capacitive sensing technique may logically divide the sensing area of the panel 234 into a plurality of capacitive pixels. By determining which capacitive pixel (or pixels) has an associated capacitance altered by the input object, the input device determines a specific location or area of the panel 234 that the input object is in contact with or hovering over. I can. As mentioned above, the sensor module 222 may use self-capacitance sensing, mutual capacitive sensing, or some combination thereof to identify the location of the input object in the sensing area.

In one embodiment, the reference voltage rails 211 are always (e.g., inductively or capacitively) disconnected from the power source 202, thus selectively shorting from the power source 202 before being modulated as described above. Need to be. Instead, the processing system 110 and the display/sensing panel 234 are separate, separate power supplies (e.g., inductive coupling to the power) coupled to the reference voltage rails 211 that only feed these components. Separate batteries or charged capacitors). As such, the reference voltage modulator 226 ensures that modulating the voltage rails 211 does not adversely affect other components in the input device 200, for example level conversion or separation in the communication interfaces is important. Without needing to guarantee, it is possible to modulate these voltage rails 211 for capacitive sensing.

Components in processing system 110 may be arranged in many different configurations on one or more integrated circuits (chips). In one embodiment, the sensor module 222, the display module 224, and the reference voltage modulator 226 may be disposed on the same integrated circuit. In one embodiment, the sensor module 222 may be disposed on a different integrated circuit than the reference voltage modulator 226. In another embodiment, the sensor module 222, the display module 224, and the reference voltage modulator 226 may be disposed on three separate integrated circuits. In another embodiment, the sensor module 222 and the reference voltage modulator 226 are disposed on the same integrated circuit, while the display module 224 is disposed on separate integrated circuits. Furthermore, in one embodiment, the display module is disposed on one integrated circuit, but the sensor module 222 and at least a portion of the display circuit 236 (e.g., source driver, mux, or TFT gate driver) are second integrated. Is disposed on the circuit, and the reference voltage modulator 226 is disposed on the third integrated circuit.

In one embodiment, the processing system 110 includes an integrated circuit comprising a power management controller 230, a timing controller 220, and a high speed link 244 for coupling to a host 204. The integrated circuit may also include receivers and sources drivers for performing display updating and capacitive sensing. Moreover, this integrated circuit may be disposed on the same substrate supporting the display/sensing panel 234 instead of being located on different substrates. The common substrate may include traces coupling the integrated circuit to the display and sensor electrodes 240 and 242.

Moreover, in some displays (eg, LED or OLED), a backlight may not be required. Nevertheless, the reference voltage rail modulation techniques described above may be used to perform capacitive sensing.

3 is an input device 300 that modulates reference voltage rails for performing capacitive sensing, according to an embodiment described herein. The input device 300 includes a voltage regulator 315 for controlling and maintaining the rail voltages V _DD and V _GND provided by a power supply (not shown). In one embodiment, voltage regulator 315 may be replaced with a battery and/or power controller 230 may separate modulated power domain 310 from unmodulated power domain 305. Similar to input device 200, device 300 includes a timing controller 220 that outputs control signals 330A, 330B that control switches 210, 212 (i.e., transistors). . As above, before modulating the reference voltage rails 211 (V _{DD _MOD} and V _{GND_MOD} ), the timing controller 220 opens the switches 210 and 212 to set the reference voltage rails 211 to the reference voltage. Are electrically shorted from V _DD and V _GND .

When the reference voltage rails 211 are electrically isolated from the reference voltages V _DD and V _GND , the input device 300 has two separate power domains-i.e., unmodulated power domain 305 and modulated. It has a power domain 310. Unmodulated power domain 305 includes components to the left of dotted line 301, while modulated power domain 310 includes components to the right of dotted line 301. The components in the unmodulated power domain 305 operate using the unmodulated, DC reference voltages V _DD and V _GND , while the components in the modulated power domain 310 are reference voltage rails ( 211) is operated by using the modulated reference voltages V _{DD _MOD} and V _{GND _ MOD} . As above, the reference voltage rails 211 are modulated by the modulated signal 228 generated by the reference voltage modulator 226. For example, modulated signal 228 may be driven with a voltage less than V _DD /2, which may be the input voltage to receiver 325. In one embodiment, the reference voltage modulator may be located on the power management controller 230 or the source driver instead of on the timing controller 220 as shown.

As shown, timing controller 220 includes a high speed data interface 320 (eg, eDP or MIPI standard interface) in the unmodulated power domain 305. As such, at least one of the modules in the timing controller 220 is in the unmodulated power domain 305 while at least one of the modules is in the modulated power domain 310. Although not shown, the sensor module and display module may also be in the modulated power domain 310. Moreover, although the reference voltage modulator 226 is shown as being in the modulated power domain 310, the modulator 226 will also generate a modulated signal 228 for the chassis ground in the unmodulated power domain 305. As it may be, it may be considered to be in the unmodulated power domain 305. The communication module may further provide modulated signals 228 and power domain separation controls 330.

By placing the high speed data interface 320 in the unmodulated power domain 305, the timing controller 220 can communicate directly to the host 204. That is, because both data interface 320 and host 204 are in unmodulated power domain 305, they may transmit data signals directly. In contrast, if the interface 320 was in the modulated power domain 310 and operated using its modulated reference voltages, then the interface 320 is from the host 204 without a substantial increase in cost, power, and design time It may not be possible to detect and identify the received data signals. Although not shown, timing controller 220 may include level shifters that allow high speed data interface 320 to communicate with other modules in timing controller 220. For example, when receiving update display data from host 204, high speed data interface 320 may use level shifters when transmitting the display data to a display module in modulated power domain 310.

In another embodiment, the overall timing controller 220 may be in the modulated power domain 310. To communicate with the host 204, a separate communication module may be communicatively coupled between the host 204 and the controller 220. For example, the communication module may be located on an integrated circuit separate from the timing controller 220. The communication module may transmit data signals to the timing controller 220 in the modulated power domain 310 and the data signals received from the timing controller 220 may be transmitted to the host 204 in the unmodulated power domain 305. It may also include one or more level shifters that allow it to be.

The reference voltage modulator 226 includes a receiver 325 that captures the resulting signals from the display and sensor electrodes in the panel 234 when modulating the reference voltage rails 211. Receiver 325 may modulate rails 211 using the same electrical connection used by modulating signal 228 to capture the resulting signals as well. That is, the reference voltage modulator 226 may use the same port to transmit the modulated signal 228 and capture the resulting signals from the display and sensor electrodes in the display/sensing panel 234. Alternatively, the reference voltage modulator 226 may use the display/sensing panel 234 only to receive signals, while the modulating signal 228 may be applied to another component (e.g. )) to the reference electrode.

In the input device 300, the power management controller 230 includes a number of power sources 335 that output a number of different DC voltages to the panel 234 via links 340. In order to generate various voltages, the power supplies 335 use inductive boost circuits or capacitive charge pumps, the voltages provided by the reference voltage rails 211 (i.e. V _{DD _MOD} and V _{GND _MOD} ) To the voltages required by the components in panel 234-for example, V _GH , V _GL , VCOM, etc. In one embodiment, when the reference voltage modulator 226 modulates the reference voltage rails 211, the power management controller 230 may deactivate the power supplies 335 (e.g., the input device is low-power In the state). However, when the input device 300 performs display updating or capacitive sensing when the voltage rails 211 are not being modulated, the power supplies 335 are active to provide DC power to the panel 234. May be.

4 is an input device 400 that modulates reference voltage rails for performing capacitive sensing, according to an embodiment described herein. In contrast to the input device 300 in FIG. 3, the input device 400 includes a reference voltage modulator 410 that does not capture the resulting signals when modulating at least one of the voltage rails 211. As shown, the reference voltage modulator 410 includes a transmitter 415 for generating a modulated signal 228 and is disposed in the power management controller 230. However, the receiver 325 is not located to the modulator 410. Instead, the receiver 325 is located outside of the modulator 410 in the timing controller 220 (however, it can also be located somewhere else in the processing system 110, for example on a separate integrated circuit. ). Thus, in this embodiment, the electrical path used to capture the resulting signals is different from the electrical path used to drive the modulated signal 228. Further, as indicated herein, when capacitive signals are provided by, for example, capacitor 405, a direct resistance connection between receiver 325 and modulated rail 211 is not required. Thus, FIGS. 3 and 4 illustrate that the resulting signals can be captured through one of the voltage rails 211. In one embodiment, receiver 325 is in the lowest impedance path for modulating signal 228 to couple to the electrodes in display/sensing panel 234. In one embodiment, the transmitter 415 also drives the modulating signal 228 on the reference voltage rails 211 using the connection of the power management controller to the reference voltage rails 211.

As shown, capacitor 405 is located in the electrical path that couples receiver 325 to voltage rail 211A, but capacitor 405 is optional. The receiver 325 determines when the input object is closest to the display/sensing panel 234, the charge ( Alternatively, voltage) can also be measured.

5 is a circuit diagram of the reference voltage modulator 226 shown in FIG. 3, according to one embodiment described herein. The modulator 226 includes an integrator 500 that outputs a modulated signal 228. Moreover, since integrator 500 functions as a receiver, the modulator also captures resulting signals from the display and sensor electrodes at the output of integrator 500. One input of the amplifier in the integrator 500 is coupled to a signal generator 515 that outputs a modulated signal that the integrator 500 will then use to drive the modulated signal 228 through feedback from the sensor output. For example, the integration function may be performed by a capacitor 525, for example in a low pass filter, such that the offset drift is compensated by, for example, a reset switch or an optional resistor 520.

Generally describing the function of the reference voltage modulator 226, the integrator 500 modulates the charge that the amplifier must provide through the capacitor 525 in order to modulate the display and sensor electrodes in the display panel by modulating the reference voltage rails. Measure the amount of (using the resulting signals). Although not shown, receiver 325 may be coupled to a filter and sampling circuit-such as an ADC-to process the resulting signals. Moreover, FIG. 5 only illustrates an example of a suitable structure for the reference voltage modulator 226 and receiver. Generally speaking, modulator 226 may be any kind of transmitter circuit that drives modulated signal 228 and any kind of analog circuit that receives measurements of capacitance or changes in capacitance within the circuit. Alternatively, as shown in FIG. 4, receiver 325 may be separate from the reference voltage modulator. For example, the reference voltage modulator may only include a modulator that drives the modulating signal 228, while the receiver may be located somewhere else in the processing system (e.g., a separate integrated circuit, power management controller, etc.). .

6 is a flow diagram illustrating a method 600 of waking up an input device from a low power state using modulated reference voltage rails, according to an embodiment described herein. At block 605, the timing controller electrically separates the reference voltage rails from the power source by selectively shorting the rails or by using an indirect coupling method such as inductive coupling. For example, the power source may be a battery that provides DC voltage outputs (eg, V _DD and V _GND ) to power various components in the input device. Since the function of some components may be negatively affected by modulating the outputs of the power source, the timing controller electrically disconnects the reference voltage rails from the battery. Alternatively, when updating the display of the input device or performing capacitive sensing that does not modulate the reference voltage rails, the timing controller may allow the reference voltage rails to be electrically connected to the power source. During these time periods, the power source may drive unmodulated, DC voltages directly on the voltage rails. In some embodiments, power may be provided consistently, even while voltage rails are modulated, floated, or maintained at a relatively constant voltage relative to chassis ground (e.g., voltage rails Is inductively coupled to).

At block 610, the input device configures the input device in a low-power state. In one embodiment, the input device may determine to enter a low-power state after identifying a period of inactivity if the user fails to interact with the input device. For example, if the user does not use the function of the input device within a predefined time period (e.g., does not touch the sensing area, make a call, tap a button, etc.), the input device will be low- You can also switch to the power state. In another example, the user may instruct the input device to enter a low-power state by performing a predefined gesture in the sensing area or activating a specific button.

In a low-power state, the input device saves power by deactivating one or more components of the input device (eg, power supplies, PMICs, backlight, etc.). As shown in Fig. 2, since the reference voltage modulator 226 captures the resulting signals for performing capacitive sensing, the sensor module 222 and the corresponding capacitive sensing circuit in the display/sensing panel 234 ( If yes) may be disabled. Similarly, if a low-power state does not need to display an image, the display module 224 and the display circuit 236 can be deactivated. Moreover, the input device can effectively deactivate components in the display/sensing panel 234 by deactivating the power management controller 230 that stops supplying power to the panel 234. Also, deactivating the power management controller 230 may turn off the backlight 232. In one embodiment, the low-power state indicates that at least all powered components in the sensor module 222, display module 224, power management controller 230, and display/sensing panel 234 are deactivated. it means. However, in other embodiments, some of these components may remain powered in a low-power state.

At block 615, the reference voltage modulator modulates the reference voltage rails with respect to the chassis ground of the input device. At block 620, while modulating the voltage rails, the receiver simultaneously captures the resulting signals from the display and sensor electrodes in the panel. To do this, the receiver may be coupled to a common electrical node-eg a supply voltage, to the display and sensor electrodes in the panel. Using the resulting signals, the receiver (or other component in the input device) determines a capacitance corresponding to the display and sensor electrodes or a change in capacitance. By comparing this capacitance measurement to one or more thresholds, the input device can detect when the input object is close to the panel.

While the receiver may be integrated into a reference voltage modulator that generates a signal to modulate the reference voltage rails, the receiver may be located somewhere on the processing system that allows it to be coupled to the display electrode and/or sensor electrode in the panel. For example, the receiver may be located together on a separate integrated circuit or at a location in a timing controller different from the reference voltage modulator. Moreover, the receiver may be located on the power management controller. In one embodiment, regardless of its location, the receiver is coupled to one (or both) of the reference voltage rails being modulated.

At block 625, the input device determines whether the input object is proximate the display/sensing panel by evaluating the resulting signals captured at block 620. If the input object is not in proximity to the input device (eg, not touching the panel or hovering over the panel), method 600 proceeds to 620 where the receiver captures the resulting signals again while the voltage rails are modulated. For example, when in a low-power state, the input device may modulate the reference voltage rails at intervals to capture the resulting signal until the input object is detected. The duty cycle of these low power cycles is low-for example greater than 10 ms-but fast enough to track changes in the environment-but may for example be faster than 100 seconds.

If an input object is detected at block 625, the method 600 proceeds to block 630, where the input device switches to an active state. In one embodiment, upon switching from a low-power state to an active state, at least one component that has been deactivated or has been powered down to a low-power state is activated. For example, the input device may determine a specific location of the input object in the panel by activating the sensor module and the capacitive sensing circuit on the panel to perform capacitive sensing. Alternatively or additionally, the input device may activate the display module and display circuit (and backlight) such that the image is displayed. In some low power modes, no modulation of the reference voltage is required when interference is being detected or when detecting the presence of an active pen. For example, when performing interference or active pen detection, the duty cycles may be slow (eg, less than 100 ms).

In one embodiment, when in an active state, some of the components in the input device may still be deactivated. For example, at block 630, the input device may determine the location of the input object in the panel by activating only the components necessary to perform capacitive sensing. Display components (eg, backlight or display module) may still be deactivated. For example, when in an active state, the input device may use a sensor module to ensure that the input object detected at block 625 was not false positive prior to activating the display components. In another example, the reference voltage modulator can detect when an input object approaches (eg, hovers above) the display, which causes the input device to switch to an active state later at block 630. However, before activating the display elements, the input device may determine whether the user has performed a predefined wake-up gesture using the input object, using the sensor module. Thus, although not shown in method 600, the active state draws more power than the low-power state, but draws less power than the fully active state where both display updating and capacitive sensing are performed, for example. It may be in the middle power state.

7 illustrates an exemplary electrode arrangement for performing capacitive sensing, according to an embodiment described herein. 7 shows a portion of an exemplary sensor electrode pattern including sensor electrodes 710 configured to sense in a sensing area associated with the pattern, in accordance with some embodiments. For clarity of illustration and description, FIG. 7 shows a pattern of simple rectangles and does not show various components. Further, as illustrated, the sensor electrodes 710 include a first plurality of sensor electrodes 720 and a second plurality of sensor electrodes 730.

In one embodiment, the sensor electrodes 710 may be arranged on different sides of the same substrate. For example, each of the first and second plurality of sensor electrode(s) 720 and 730 may be disposed on one of the surfaces of the substrate. In other embodiments, the sensor electrodes 710 may be arranged on different substrates. For example, each of the first and second plurality of sensor electrode(s) 720, 730 may be disposed on surfaces of separate substrates that may be attached together. In another embodiment, the sensor electrodes 710 are all located on the same side or surface of a common substrate. In one example, the first plurality of sensor electrodes includes jumpers in regions where the first plurality of sensor electrodes intersect the second plurality of sensor electrodes, wherein the jumpers are insulated from the second plurality of sensor electrodes.

The first plurality of sensor electrodes 720 may extend in a first direction, and the second plurality of sensor electrodes 730 may extend in a second direction. The second direction may be similar or different from the first direction. For example, the second direction may be parallel to, perpendicular to, or diagonal to the first direction. Further, the sensor electrodes 710 may each have the same size or shape, or different sizes and shapes. In one embodiment, the first plurality of sensor electrodes may be larger (larger surface area) than the second plurality of sensor electrodes. In other embodiments, the first plurality and the second plurality of sensor electrodes may have a similar size and/or shape. Accordingly, the size and/or shape of one or more of the sensor electrodes 710 may be different from the size and/or shape of one or more of the sensor electrodes 710. Nonetheless, each of the sensor electrodes 710 may be formed in any desired shape on their individual substrates.

In other embodiments, one or more of the sensor electrodes 710 are disposed on the same side or surface of a common substrate and separated from each other in the sensing area. The sensor electrodes 720 may be arranged in a matrix array, where each sensor electrode may be referred to as a matrix sensor electrode. Each sensor electrode of the sensor electrodes 710 in the matrix array may be of substantially similar size and/or shape. In one embodiment, one or more of the sensor electrodes of the matrix array of sensor electrodes 710 may vary in at least one of a size and shape. Each sensor electrode in the matrix array may correspond to a pixel in the capacitive image. Further, two or more sensor electrodes of the matrix array may correspond to pixels of the capacitive image. In various embodiments, each sensor electrode of the matrix array may be coupled to a separate capacitive routing trace of a plurality of capacitive routing traces. In various embodiments, the sensor electrodes 710 comprise one or more grid electrodes disposed between at least two sensor electrodes of the sensor electrodes 710. The grid electrode and at least one sensor electrode may be disposed on a common side of the substrate, on different sides of the common substrate, and/or on different substrates. In one or more embodiments, the sensor electrodes 710 grid electrode(s) may cover the entire voltage electrode of the display device. Although the sensor electrodes 710 are electrically isolated on the substrate, the electrodes may be coupled together outside of the sensing area-for example in the connection area. In one embodiment, the floating electrode may be disposed between the grid electrode and the sensor electrodes. In one particular embodiment, the floating electrode, the grid electrode and the sensor electrode comprise all of the common electrode of the display device.

The processing system 110 shown in FIG. 1 is to determine changes in the absolute capacitance of the sensor electrodes 710 with modulated signals (i.e., absolute capacitive sensing signals). It may be configured to drive one or more sensor electrodes. In some embodiments, the processing system 110 is configured to drive the transmitter signal onto the first sensor electrode of the sensor electrodes 710 to receive the resulting signal with the second sensor electrode of the sensor electrodes 710. The transmitter signal(s) and the absolute capacitive sensing signal(s) may be similar in at least one of shape, amplitude, frequency and phase. The processing system 110 may be configured to drive the grid electrode with a shielding signal to drive the grid electrode as a shielding and/or protective electrode. In addition, the processing system 110 uses the grid electrode as a transmitter signal so that the capacitive coupling between the grid electrode and one or more sensor electrodes can be determined, or as an absolute capacitive sensing signal so that the absolute capacitance of the grid electrode can be determined. It may be configured to drive.

As used herein, a shielding signal refers to a signal having either a constant voltage or a variable voltage signal (protection signal). The guard signal may be substantially similar to a signal in which at least one of amplitude and phase modulate the sensor electrode. Further, in various embodiments, the protection signal may have an amplitude greater or less than the amplitude of the signal modulating the sensor electrode. In some embodiments, the protection signal may have a different phase than the signal modulating the sensor electrode. Electrically floating the electrode can be interpreted as a type of protection by floating, in cases where the second electrode receives the desired protecting waveform via capacitive coupling from an adjacent driven sensor electrode of the input device 100. have.

As described above, in any of the sensor electrode arrangements described above, the sensor electrodes 710 may be formed on a substrate outside or inside the display device. For example, sensor electrodes 710 may be disposed on an outer surface of a lens in input device 100. In other embodiments, sensor electrodes 710 are disposed between the color filter glass of the display device and the lens of the input device. In other embodiments, at least a portion of the sensor electrodes and/or grid electrode(s) may be disposed such that they are between the thin film transistor substrate (TFT substrate) and the color filter glass of the display device 160. In one embodiment, the first plurality of sensor electrodes are disposed between the TFT substrate and the color filter glass of the display device 160, and the second plurality of sensor electrodes are disposed between the color filter glass and the lens of the input device 100. do. Also in other embodiments, all of the sensor electrodes 710 are disposed between the TFT substrate and the color filter glass of the display device, wherein the sensor electrodes are disposed on the same substrate or on different substrates as described above. It could be.

In any of the sensor electrode arrangements described above, the sensor electrodes 710 are for transcapacitance sensing or for absolute capacitive sensing by dividing the sensor electrodes 710 into a transmitter electrode and a receiver electrode, or It may be operated by the input device 100 for some mixing of both. Further, one or more of the sensor electrodes 710 or display electrodes (eg, source, gate, or reference (Vcom) electrodes) may be used to perform shielding.

Regions of the localized capacitive coupling between the first plurality of sensor electrodes 720 and the second plurality of sensor electrodes 730 form capacitive pixels. The capacitive coupling between the first plurality of sensor electrodes 720 and the second plurality of sensor electrodes 730 is performed with the first plurality of sensor electrodes 720 and the second plurality of sensor electrodes 730 It changes according to the proximity and motion of the input objects in the associated sensing area. Further, regions of localized capacitance between the first plurality of sensor electrodes 720 and the input object and/or the second plurality of sensor electrodes 730 and the input object also form capacitive pixels. In this way, the absolute capacitance of the first plurality of sensor electrodes 720 and/or the second plurality of sensor electrodes is detected associated with the first plurality of sensor electrodes 720 and the second plurality of sensor electrodes 730. It changes according to the proximity and motion of the input objects in the area.

In some embodiments, the sensor pattern is “scanned” to determine these capacitive couplings. That is, in one embodiment, the first plurality of sensor electrodes 720 are driven, for example, by the sensor module 222 in FIG. 2 to transmit transmitter signals. Transmitters may be operated such that one transmitter electrode transmits at a time or multiple transmitter electrodes transmit simultaneously. If multiple transmitter electrodes transmit simultaneously, these multiple transmitter electrodes may transmit the same transmitter signal and effectively create a larger transmitter electrode, or these 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 a second plurality of sensors.

The receiver sensor electrodes may be operated alone or in multiple to capture the resulting signals. The resulting signals may be used to determine measurements of capacitive couplings in capacitive pixels. Receive electrodes may also be scaled (eg, by a multiplexer) with a reduced number of capacitive measurement inputs to receive signals.

In other embodiments, scanning the sensor pattern comprises driving one or more sensor electrodes of the first and/or second plurality of sensor electrodes with absolute sensing signals while receiving result signals with the one or more sensor electrodes. do. The sensor electrodes may be driven and received so that one second electrode is driven and received at a time or a plurality of sensor electrodes are driven and received at the same time. The resulting signals may be used to determine measurements of capacitive couplings at the capacitive pixels or along each sensor electrode.

The set of measurements from capacitive pixels form a "capacitive frame". The capacitive frame may include a "capacitive image" representing capacitive couplings in the pixels and/or a "capacitive profile" representing capacitive couplings along each sensor electrode. Multiple capacitive frames may be captured over multiple periods of time used to derive information about the input to the sensing region, and differences between them. For example, successive capacitive frames captured over successive time periods may be used to enter, exit, and track the motion(s) of one or more input objects within the sensing area.

The background capacitance of the sensor device is a capacitive frame that is not associated with any input object in the sensing area. Background capacitance varies depending on the environment and operating conditions, and may be estimated in several ways. For example, some embodiments take “baseline frames” when no input object is determined to be in the sensing area, and use those baseline frames as estimates of their background capacitances.

Capacitive frames can be adjusted for the background capacitance of the sensor device for more efficient processing. Some embodiments achieve this by “baselining” measurements of capacitive couplings in capacitive pixels to generate “baselined capacitive frames”. That is, some embodiments compare the measurements that form the capacitance frames to suitable “baseline values” of “baseline frames” and determine changes from that baseline image. These baseline images may also be used in the low power modes or active modulated active pens described above for profile sensing.

Interference and active pen detection

8 is an input device 800 for detecting a noisy (ie, interfering) signal or a communication signal from an active input object, according to an embodiment described herein. The input device 800 has a structure similar to the input device 300 in FIG. 3, and in fact, the individual input devices may be capable of performing interference and active input object detection as well as the reference voltage modulation described in FIG. 3. . However, in other embodiments, the input device may be configured to only perform one of these functions. In one embodiment, the active object is actively modulated with respect to chassis ground, with a known or configurable frequency, duty cycle, timed encoding, etc.

The timing controller 805 at the input device 800 includes a central receiver 810 coupled to a low reference voltage rail 211B. Similar to receiver 325 in FIG. 3, central receiver 810 is coupled with the display and sensor electrodes in display/sensing panel 234 via power sources in power management controller 230. In one embodiment, the voltage rails 211 may also be directly coupled to the panel 234, but are indirectly coupled to other components in the panel 234 through power sources in the controller 230. As such, the central receiver 810 may be directly coupled to some components in the display/sensing panel 234. In either case, all electrodes (and possibly other components in panel 234) are coupled to a common electrical node with central receiver 810, so panel 234 functions as a single capacitive pixel. can do.

However, the central receiver 810 need not be coupled to both the display and sensor electrodes in the panel 234 but may instead be coupled only to the display electrodes or only the sensor electrodes. However, by limiting the number of electrodes coupled with the central receiver 810 (e.g., to a single source driver), the size of the sensing area in the panel 234 (or the sensitivity of the capacitive pixel) is Even if the electrodes are scanned across, it may be reduced so that a small part of the panel is measured.

Unlike the embodiment shown in FIG. 3, the input device 800 modulates the reference voltage rails 211 to detect interference or communication signals from an active input object (e.g., a stylus or pen with a wireless transmitter). I never do that. Instead, rails 211 may maintain unmodulated, DC voltages relative to the chassis ground. However, similar to in FIG. 3, the timing controller 805 may electrically short the voltage rails 211 from the power source voltages V _DD and V _GND prior to detecting an interference or communication signal. Using signals 330A, 330B, timing controller 805 shorts voltage rails 211 from the power source voltages by opening switches 210, 212. Alternatively, the reference voltage rails 211 may be inductively coupled to the power source voltages, in which case the rails 211 are always separated from these voltages.

When the noise source or active input object is close to the electrodes on the panel 234, the interfering signal generated by the noise source or the digital communication signal generated by the input object will cause the resulting signals to be captured later by the central receiver 810. Sensor electrodes in panel 234 and on the display. By processing the resulting signals, the input device 800 can identify the interfering signal and compensate for it. Some non-limiting examples of actions the input device 800 may take to compensate for interfering signals include switching different detection frequencies, limiting the number of input objects to be reported, proximity detection or glove detection and Stop using some features such as, increasing the number of frames averaged before detecting the touch location, ignoring any new input objects that are detected when interference occurs, the sensor that the input object has left the sensing area Preventing the module from reporting, or changing the capacitive frame rate.

If the resulting signals are brought about by the active input object, the input device 800 can decode the digital signal and perform a corresponding action. When an active input object transmits a communication signal using a wireless transmitter, the display and sensor electrodes on panel 234 function as antennas for receiving the signal. Thus, neither a noise source nor an active input object need to be in contact with panel 234 to generate the resulting signals on the electrodes in panel 234-for example, the input object may be hovering over panel 234. have.

Moreover, display/sensing panel 234 includes a number of local receivers 815 that may each be coupled to a respective sensor electrode in panel 234. When performing capacitive sensing, local receivers 815 measure the resulting signals from individual sensor electrodes that can be used to identify a particular location in panel 234 that is in contact with the input object or hovering over it. . In one embodiment, local receivers 815 may perform a function similar to receiver 810-that is, both receivers 810 and 815 measure the capacitance. In one embodiment, instead of using the central receiver 810 to detect an interfering or communication signal from an active input object, the input device combines all resulting signals received by the local receivers 815 on the panel 234. can do. However, detecting interfering signals and communication signals may require more power, or more complex or expensive circuitry than the circuit required to perform capacitive sensing using only the receiver 810. As such, if local receivers 815 were used to detect interfering or communication signals, they may be more expensive than local receivers 815 used to perform capacitive sensing using only the modulated signal. Thus, instead of having multiple receivers 815 that are expensive, input device 800 may use only one central receiver 810 that can be used to detect interference and communication signals. The central receiver 810 may have a larger dynamic range, faster ADC, and/or more noise immunity than the local receivers 815 such that the local receivers 815 are made more expensive than the central receiver 810. There may be. Thus, in one embodiment, instead of having dozens or hundreds, or expensive local receivers 815 capable of discriminating interference and communication signals from an active input object, input device 800 has only one-i.e. central receiver ( 810). Because local receivers 815 may not be used to detect interference or communication signals, they may be more expensive than those otherwise possible.

In one embodiment, interference or communication signals may be measured while the display is being updated. That is, the timing controller may comprise a display module that is actively updating pixels in the display/sensing panel 234 while the central receiver 810 is capturing signals as described above. Although the power management controller 230 and panel 234 are selectively shorted (or separated) from the power source voltages V _DD and V _GND , the charge stored in the bypass capacitor 214 is transferred to the voltage rails 211. It can be used to power on and enable display updating. When the charge across the capacitor 214 falls to a threshold, the timing controller 805 reconnects the voltage rails 211 and the capacitor to the power source voltages V _DD and V _GND , or otherwise rails the power source voltages. May be coupled (eg, inductively coupled) to s 211. Moreover, the central receiver 810 may stop measuring interference or communication signals when the voltage rails 211 are ohmically coupled to the power source voltages V _DD and V _GND . However, the capacitor 214 (e.g., 15-150 microfarads) has sufficient time to allow the central receiver 810 to discern an interfering signal caused by noise or a communication signal provided by an active pen or stylus. In the meantime, it may store enough charge to feed power management controller 230 and panel 234.

9 is a circuit diagram of a central receiver 810 for capturing resulting signals to identify a noise or communication signal, in accordance with an embodiment described herein. The central receiver 810 includes an integrator 900 for capturing result signals from the sensor electrodes and a display similar to the integrator 500. The integrator 900 may be implemented as a low-pass filter with a feedback capacitor 915 and an optional resistor 920 when the feedback signal is measured and controls the reference voltage on one of the rails 211. As shown, one input of the amplifier in integrator 900 is coupled to V _GND (eg, chassis ground or V _DD /2). In one embodiment, the central receiver 810 is the lowest impedance path between the noise source or active pen and chassis ground. As such, interfering signals generated by a noise source or resulting signals caused by a communication signal generated by an input object flow through the central receiver 810, rather than through other components in the input device. Thus, it is measured by the central receiver 810. In other words, by selectively shorting or separating the voltage rails from the power source, the central receiver 810 becomes the lowest impedance path between the noise source and the active input object and the chassis ground, so that the noise source and the active input object The resulting signals generated by flow primarily through a central receiver 810 and integrator 900 from which signals can be measured.

Integrator 900 is, however, only one type of circuit suitable for performing the function of central receiver 810. Generally speaking, the central receiver 810 can be any analog circuit that measures capacitance. For example, the central receiver 810 may include a circuit that measures the accumulated charge or voltage across the capacitor 925, or a circuit that measures the capacitance using a current flowing through the central receiver 810. .

10 is a flow diagram illustrating a method 1000 for identifying a noise or communication signal using capacitive sensing, in accordance with an embodiment described herein. At block 1005, the input device separates the reference voltage rail from the power source. For example, the switches may selectively short the reference voltage rails from the power source or the rails may be permanently separated from the power source by inductive coupling. In one embodiment, a capacitor (e.g., bypass capacitor 214 shown in FIG. 8) is a component in the input device that is fed by reference voltage rails that may be shorted when capacitive sense signals are received. It may be connected between rails to provide temporary power to the device. For example, display updating and capacitive sensing may be performed while voltage rails are disconnected from the power source.

At block 1010, the central receiver is coupled to the chassis ground (through its power sources) and to one or more display electrodes and/or sensor electrodes in the display/sensing panel. Moreover, the central receiver may provide a low impedance path between the electrodes and ground. Thus, when a noise source is capacitively coupled to the electrodes in the panel or a communication signal from an active input device is received on the electrodes, a current loop is formed that flows through the central receiver.

At block 1015, the central receiver simultaneously captures the resulting signals from the display and sensor electrodes. For example, display electrodes, sensor electrodes, and a central receiver may be coupled to a common electrical node such that a combination of the resulting signals generated on the display and sensor electrodes flows through the receiver and reaches chassis ground.

In one embodiment, the central receiver may capture the resulting signals when it is in the low-power state cited above in FIG. 6 when the display and sensor modules are deactivated. During the first period of time, the input device may capture the resulting signals while the reference voltage rails are not modulated to identify the interfering or communication signal. During the second period of time, the input device may capture the resulting signals while the reference voltage rails are modulated as described in FIG. 6. Moreover, if an interfering signal is detected during the first time period, the input device may modify the modulated signal used to modulate the voltage rails during the second time period to avoid harmful interference from the noise source. However, as noted above, method 1000 may also be performed alone or in parallel with display updating when the input device is in an active or high-power state.

In block 1020, the input device identifies at least one of an interfering signal and a communication signal from the active input device based on the acquired result signals. If an interfering signal is identified, the input device may compensate for that signal by, for example, switching a modulated signal outside the range of the interfering signal when performing capacitive sensing. When a communication signal is received, the input device may process the signal to determine information about the active input object. For example, the communication signal may be the current slope of the input object relative to the display/sensing panel, a specific color or marking to be displayed at the location where the input object contacts the panel, or another object attempting to pair with the input object or input device For example, it is also possible to identify an ID for Bluetooth connection). In another example, the communication signal may be switching to a low-power state, waking up from a low-power state, opening a specific application, using an input object to change the shape of markings made on the display, etc. Indicate to the input device that a button on the input object, which may correspond to a specific function in the same input device, has been pressed by the user.

In one embodiment, when a communication signal is received, the input device may increase the number of detection frames used to detect the input object for multiple capacitive frames. Alternatively or additionally, the input device performs a coarse search (sensing using groups of sensor electrodes), and once the position of the input object is detected during the coarse search, subsequent granular search (local receiver By performing the detection on each sensor electrode using individually), it is also possible to search for the location of the input object in the detection area.

Mitigating the Effects of Low Ground Mass

11 illustrates various capacitances between an input device and its environment, according to an embodiment described herein. As shown, system 1100 includes an input device 1105, an input object 1110, and a ground 1115, which are capacitively coupled. The input device 1105 includes a sensing area 1120 on the display/sensing panel described above for performing capacitive sensing. In one embodiment, by measuring the change in capacitance between the sensing area 1120 and the input object 1110 (C _T ), the input device 1105 is in contact with the input object 1110 and the sensing area 1120 Or you can decide whether to hover above. In some examples, the input device 1105 may determine a particular location in the sensing area 1120 with which the input object 1110 is interacting.

When performing capacitive sensing, however, the resulting signals measured by input device 1105 may also be affected by other capacitances in system 1100 besides C _T. For example, input object 1110 may be capacitively coupled to the chassis of input device 1105 indicated by C _BC . Further, both the input object 1110 and the chassis of the input device 1105 are generally capacitively coupled to ground 1115, as both are represented by C _IG and C _BG , respectively. The capacitances C _BC , C _BG , and C _IG are referred to herein as ground states 1125. In general, input device 1105 is unable to control capacitances in ground conditions 1125 that change as the environment of device 1105 changes. For example, the capacitance C _BC between the input object 1110 and the chassis changes depending on whether the user is holding the input device 1105 or whether the device 1105 is placed on a table. Moreover, when the user is standing on earth or in an aircraft, the capacitance C _IG between the input object 1110 and ground 1115 changes. Input device 1105 may not have any mechanism to measure the position of input device 1105 and input object 1110 in its environment, so the capacitances at ground states 1125 measure C _T It may not be possible to accurately determine whether it affects the capabilities of the input device 1105 to perform.

The capacitance C _T between the sensing region 1120 and the input object 1110 is generally the smallest capacitance shown in FIG. 11, since it is a limiting impedance, it is the amount of signal received at the input object 1105. Dominate. However, since the capacitances in the ground conditions 1125 decrease as the position of the input device 1105 or input object 1110 in the environment changes, these capacitances are the input device 1105 that accurately monitors C _T. ) Can also decrease its ability. For example, to the combined capacitance of C _T in series with the ground state of the 1125 have the same value (e.g., 1-10 pF) and C _T, the signal received from the input device due to the C _T It is divided in half. For example, if the input device 1105 is positioned above the user's lap, the capacitance C _BG may be approximately 50 pF, and thus may have little effect on signals measured by the input device 1105. However, if the input device 1105 is placed on a table in contact with ground 1115, the capacitance C _BG may be approximately 5 pF. Since the capacitances C _T and C _BG are now the same, the effect on the resulting signals captured by the input device 1105 due to C _T (i.e., the capacitance the input device 1105 is trying to monitor) is It is roughly halved. Arrangements in which the capacitance at ground conditions 1125 significantly affects the resulting signals measured by the input device 1105 are referred to herein as low ground mass (LGM) conditions.

If an LGM state is present, the input device 1105 may compare the resulting signals to thresholds used to detect a touch or hover event that assumes that the capacitances of the ground states 1125 are large, in which case, The input device 1105 may fail to detect a low capacitive change in a touch/hover event. In order to accurately detect touch/hover events during the LGM state, the input device 1105 can adjust the thresholds lower independently of the LGM or based on the host control mode (eg, the battery is charging); However, as noted above, it may be difficult or impossible to detect arrangements of input device 1105, input object 1110, and ground 115 that result in an LGM condition. Instead, embodiments herein measure the resulting signals at the central receiver representing the overall capacitance of the environment (including the capacitances in ground states 1125) by modulating the reference voltage rails as described above. This total capacitance correlates to measurements made at local receivers connected to the individual sensor electrodes in the sensing area 1120. In one embodiment, the resulting signals captured by the local receivers are normalized using the resulting signals captured by the central receiver, whereby the effect of the capacitances in ground conditions 1125 on the local capacitance measurements. Offset (or mitigate). In another embodiment, the thresholds are adjusted to utilize the estimated LGM based on a central receiver measurement combined with local receiver measurements.

12 is an input device 1200 that modulates reference voltage rails for performing capacitive sensing, in accordance with an embodiment described herein. Similar to the input devices shown in FIGS. 3 and 4, the input device 1200 modulates the reference voltage rails 211 to perform capacitive sensing using a reference voltage modulator 226. In one embodiment, the timing controller 220 opens the switches 210 and 212 such that the reference voltage rails 211 are shorted from the supply voltages V _DD and V _GND . As mentioned above, shorting the supply voltages adversely affects other components in the input device 1200 (not shown) where the modulating signal 228 also depends on V _DD and V _GND for power. You can also prevent it from going crazy.

The reference voltage modulator 226 includes a central receiver 1205 that captures the resulting signals generated by modulating the reference voltage rails 211. That is, while the modulated signal 228 is active, the central receiver 1205 measures the resulting signals from the display and/or sensor electrodes 240 and 242 in the panel 234. In general, since the central receiver 1205 is coupled to the reference voltage rails 211, the receiver 1205 is a panel 234 that is electrically coupled (directly or indirectly) to the voltage rails 211. It is also possible to capture the resulting signals from any of the components in. Referring to FIG. 11, in one embodiment, the resulting signals measured by the central receiver 1205 are not only capacitance C _T, but also the capacitances in ground states 1125-i.e. C _BC , C _IG , and C Affected by _BG . Moreover, although the central receiver 1205 is shown coupled to the reference voltage rail 211B, in other embodiments, the receiver 1205 may be coupled to the upper voltage rail 211A or other power sources 335. May be. In addition, the central receiver 1205 need not be located on the controller 220, but may be disposed on the same integrated circuit as the power management controller 230 or on a separate integrated circuit.

The input device 1200 also includes local receivers 1210 located on the display/sensing panel 234. In one embodiment, each of the local receivers 1210 is coupled to only one of the sensor electrodes to measure a local capacitance value corresponding to the panel 234. That is, unlike the resulting signals captured by the central receiver 1205, which is affected by the total capacitance of the display/sensing panel 234, the resulting signals measured by the local receivers 1210 are subordinate to the panel 234. -Affected by the local capacitance value for the part. The shape and size of the sub-portion of panel 234 may directly depend on the shape and size of sensor electrode 242 coupled to local receiver 1210. In one embodiment, the local receiver 1210 may be coupled to multiple sensor electrodes 242. In any case, the local receivers 1210 only measure the capacitance value for the portion of the sensing area defined by panel 234, rather than measuring the overall capacitance value for panel 234 similar to the central receiver 1205. do.

Although the input device 1200 may measure the resulting signals at the central receiver 1205 in a different (non-overlapping) time period than when the input device 1200 measures the resulting signals at the local receivers 1210, one embodiment At, the central and local receivers 1205, 1210 measure the resulting signals in parallel (e.g., both on the same local receiver 1205 and on the central receiver 1210 simultaneously). In other words, when modulating the reference voltage rails 211 with the modulating signal 228, both the central receiver 1205 and the local receivers 1210 can capture the resulting signals. The resulting signals measured by the central receiver 1205 include result signals generated by all sensor electrodes 242 (as well as other components in the panel 234 such as display electrodes 240). On the other hand, the resulting signals captured by each of the local receiver 1210 are generated on the sensor electrodes 242 and/or on only one or a subset of their thresholds. It may also be assumed that user inputs and LGM states change slowly for these measurements. As such, even measurements made at overlapping times may be combined to estimate LGM states.

Although the resulting signals measured by the central and local receivers 1205 and 1210 are different, the measured values are equally affected by the capacitances in the ground conditions 1125 shown in FIG. 11. That is, assuming that there are no changes in the arrangement of the input device 1105 relative to the input object 1110 and ground 1115 when measuring the total capacitance and when measuring the local capacitances, the ground for these measurements States 1125 are essentially the same. Based on this relationship, the input device 1200 in FIG. 12 normalizes the resulting signals received on the local receivers 1210 to mitigate or eliminate the effect of ground conditions on local capacitance measurements. The total capacitance indicated by the resulting signals received at the receiver 1205 may be used.

13 is a flow chart of a method 1300 of mitigating the effects of an LGM state, according to an embodiment described herein. At block 1305, the timing controller electrically connects the reference voltage rails from the DC power source (i.e., supply voltages V _DD and V _GND ) by selectively shorting or using an indirect coupling technique such as inductive coupling. Separate with Referring to FIG. 12, the timing controller 220 uses the gate voltages to short the reference voltage rails 211 from the DC power supply by deactivating the switches 210 and 212.

At block 1310, the reference voltage modulator generates a signal that modulates at least one of the reference voltage rails. In one embodiment, the modulation is performed on the chassis ground (eg, V _GND ). Thus, in terms of components in the input device that are not connected to the reference voltage rails, the components connected to the modulated reference voltage rail are modulating. However, in terms of the components connected to the reference voltage rail, it appears that the input object is modulating, as well as other components in the input device.

At block 1315, the central receiver captures the resulting signals from the plurality of sensor electrodes. Since the sensor electrodes may set the sensing area for the display/sensing panel, by capturing the resulting signals from the sensor electrodes, the central receiver will derive, at block 1320, a general capacitive measurement for the panel from the resulting signals I can. In one embodiment, the general capacitive measure may be the current in the input device caused by the resulting signals. Alternatively, the typical capacitive measurement may be a digital signal derived from the resulting signals using an ADC in a central receiver. In one embodiment, the general capacitive measurement is caused by the resulting signals generated on all sensor electrodes in the display/sensing panel, and represents the total capacitance of the panel. Moreover, the central receiver may capture the resulting signals from display electrodes and other circuitry in the panel to derive a general capacitive measurement. 14 illustrates an example system in which general capacitive measurements can be measured by a central receiver.

14 illustrates various capacitances between the input device 1105 and the environment 1405, according to an embodiment described herein. In one embodiment, environment 1405 includes an enclosing area proximate input device 1105. For example, the environment 1405 is not only objects that the input device 1105 touches, for example, a table on which the device 1105 is seated or a user's hand holding the device 1105, but also the input object 1110 Such as, may include objects that are capacitively coupled to the input device 1105 but may not contact the device 1105, such as a finger or a stylus. In one embodiment, environment 1405 may include ground.

As shown in FIG. 14, different components in the input device 1105 are capacitively coupled to objects in the environment 1405. For example, the environment is capacitively coupled to the back plate chassis 1410 (eg, C ₁ ) and the display/sensing panel 234 (C ₂ ). The value of these capacitances may vary depending on the location of the input device 1105 in the environment as well as the conditions of the environment (eg, humidity). For example, the values of C ₁ and C ₂ may change when the input device 1105 is seated on a table in case it is being held by a user. The capacitances C ₁ and C ₂ may at least partially define the grounding conditions of the input device 1105. As described above, if these capacitances have values similar to the capacitance C _T between the input object 1110 and the current conveyor 1420, an LGM condition may occur.

The capacitance C ₃ between the environment 1405 and the input object 1110 may also affect the ground conditions of the input device 1105. The capacitance C ₃ may vary depending on the location of the input objects relative to ground. For example, the value of C ₃ may be smaller when the user (holding the input object 1110) is standing on an insulating surface instead of standing directly on the earth. Similar to the capacitances C ₁ and C ₂ , the relative locations of the objects in the input object 1110 and the environment 1405 negatively affect the ability of the input device 1105 to measure C _T by altering the capacitance C ₃ . It can cause an LGM condition that can be crazy.

14 also includes a capacitance C _HC between the back plate chassis 1410 (which may be coupled to chassis ground) and an input object that may be part of a ground state for the input device 1105. For example, if the input device 1105 is a laptop and the input object 1110 is a user, the capacitance C _HC may change depending on whether the input device 1105 is seated on the user's lap or on a table. Moreover, FIG. 14 includes a coupling capacitance C _P between the input object 1110 and the display/sensing panel 234. In addition to being capacitively coupled to the current conveyor 1420 (and the corresponding sensor electrode coupled to the conveyor 1420), the input object 1110 can be configured to include display electrodes, other sensor electrodes, source drivers, gate line. It may be coupled to other components in panel 234, such as selection logic or the like. In one embodiment, capacitance C _P represents the total capacitance between the input object 1110 and the various components in the panel 234.

The central receiver 1205 is illustrated, in this embodiment, as an integrator that captures the resulting signals from the display electrode and/or sensor electrode (as well as other circuits) in the display/sensing panel 234. The captured signals are affected by the various capacitances in Fig. 14, and as a result, by processing the captured signals when modulating the reference voltage rails, the central receiver can detect the general capacitive sensing described in block 1320 of Fig. Measures can be derived. Although not shown, the central receiver 1205 may include a demodulator, filter, buffer, and/or ADC to process the captured signals to derive a general capacitive sensing measurement. Note that the current conveyor 1420 and central receiver integrator 1205 serve similar purposes to the integrator 500 and integrator 900 described above. Also, although 1205 is shown as a reset switch to incorporate capacitance C _FB , it is a resistor 520 for continuous time sensing, as if integrators 500 and 900 may incorporate a reset switch for discrete time sensing. A low-pass filter resistor such as) can be incorporated instead. It is also noted that the current conveyor 1420 may also be used to increase the effective dynamic range of the integrator 1205 by performing level shifting of the capacitive sense current relative to the voltage of the integrator 1205. A similar current conveyor may also be included in the integrators 500 and 900 to perform the same functions. Alternatively, if the dynamic range of the integrator 1205 is sufficient, the current conveyor 1420 may be unnecessary. Currents from the display/sensing panel 234 and the input object (eg, through separate local receiver supplies) and from the input object may be routed directly to the integrator 1205, while its reference V _REF is modulated.

The output voltage (V _OUT ) of the integrator 1205 when capturing the resulting signals may be expressed as follows:

(1)

(One)

Capacitance CB denotes the background capacitance, where C _T = C _F + C _B. The current from the display/sensing panel 234 to the rear plate chassis 1410 through the power modulation supply (V _MOD ) can be expressed as follows:

(2)

(2)

Returning to FIG. 13, at block 1325 the input device determines a local capacitive sensing measurement from each of the sensor electrodes. That is, instead of capturing the resulting signals from multiple electrodes (e.g., a group of sensor electrodes or both the display and sensor electrodes) similar to a central receiver, the input device uses each local receiver, from one sensor electrode. You can also capture the resulting signals. By processing the resulting signals, the local receivers may each determine a local capacitive sensing measure representing a localized capacitance value for a portion of the sensing region including the sensor electrode to which the local receiver is coupled. Thus, unlike normal capacitive sensing measurements induced by the central receiver, local capacitive sensing measurements may represent the capacitance for a sub-portion of the sensing area in the display/sensing panel. However, despite this difference between the normal capacitance measurement and the local capacitance measurement, both of these measurements may be equally affected by the ground conditions of the input device. That is, referring to FIG. 14, the capacitances C ₁ , C ₂ , C ₃ , C _HC and C _P may have the same effect on local and general capacitance measurements. Thus, if the values of the capacitances C ₁ , C ₂ , C ₃ , C _HC and C _P change, the local and general capacitance measurements change in a corresponding manner.

In one embodiment, local receivers may acquire result signals in parallel with a central receiver that acquires the result signals. In other words, while the input device modulates the reference voltage rail, both local and central receivers measure the resulting signals. Moreover, local and central receivers may also process the resulting signals in parallel to derive local and general capacitive sensing measurements, but this is not a requirement. One advantage of acquiring the resulting signals simultaneously on local and regular receivers is that the ground conditions are the same (eg, measured simultaneously). If the resulting signals have been captured at different times, the location of the input device in its environment may change, thereby changing ground conditions. As described below, if the ground conditions are the same when acquiring the resulting signals at both normal and local receivers, by correlating the signals, the input device can remove the effect of the ground conditions from the local capacitive measurements. However, even if the local and central receivers do not capture the resulting signals in parallel, any slow varying (relative to the rate at which capacitive measurements were taken) in ground conditions between when the local and central receivers measure the resulting signals. The change may be small, thus still allowing the input device to correlate signals, mitigating or eliminating the effects of ground conditions.

Using the circuit diagram in FIG. 14 as an example, the current measured to detect a touch through C _T in the current conveyor 1420 may be represented as follows:

(3)

(3)

The current I ₁ in Equation 2 between the display/sensing panel 234 and the rear plate chassis 1410 is strongly correlated with the current I ₂ in Equation 3. For example, each of these currents depends on the capacitances C _HP and C ₁ . As the arrangement of the input device 1105 in the environment 1405 changes, the capacitances C _HP and C ₁ may result in an LGM condition.

Returning to FIG. 13, at block 1330, the input device mitigates the effect of ground conditions on the resulting signals captured by the local receivers using the resulting signals captured by the central receiver. In one embodiment, result signals measured by the central receiver (or a general capacitive measurement derived therefrom) are used to normalize the result signals captured by the local receiver (or a local capacitive measurement derived therefrom). do. For example, the current I ₂ in Equation 3 (eg, a local capacitive sensing measure) can be normalized by dividing by the current I ₁ in Equation 2 (eg, a typical capacitive sensing measure).

(4)

(4)

The normalized current shown in Equation 4 is more for the capacitances forming ground states compared to the dependencies in currents I ₁ and I ₂ resulting in a normalized current that is not strongly correlated to the capacitances C _HC and C ₁ . Has little dependency In other words, changes in the values of the capacitances C _HC and C ₁ result in small changes (or no change) for the normalized current when compared to the changes in the non-normalized currents I ₁ and I ₂ . May result.

15 is a chart 1500 illustrating results of mitigating the effects of an LGM condition, in accordance with an embodiment described herein. Specifically, the upper plot 1505 illustrates the corrected local receiver signal that has been normalized using the resulting signals captured by the central receiver, while the lower plot 1510 illustrates the uncorrected signal. As shown, the upper plot 1505 is more than the lower plot 1510, the capacitive coupling between the input object 1110 and the back plate chassis 1410 (i.e. C _HC ) and the back plate chassis 1410 and the environment Less sensitive to changes in the capacitive coupling (i.e. C ₁ ) between (1405). Thus, the changes in the values of the ground state capacitances C _HC and C ₁ are for the normalized capacitive sensing signals in plot 1505, rather than the unnormalized capacitive sensing signals in plot 1510. Has less impact.

Another advantage of normalizing local capacitive sensing measurements using normal capacitive sensing measurements is that the normalized signals do not depend on V _MOD . Thus, any noise coupled to the voltage used to modulate the reference voltage rails is canceled out. Even further, normalizing local and general capacitive measurements may also mitigate noise introduced by objects that cause ground conditions. For example, referring to FIG. 14, any noise introduced to the input device 1105 through the coupling capacitances C ₁ , C ₂ , C ₃ , C _HC and C _P is captured by local and central receivers. It may be canceled out by correlating the resulting signals. Thus, any noise signal introduced by ground state capacitances coupling the input device to external objects can be eliminated.

The first group of example implementations may be described as follows:

In a first example, the input device,

A plurality of sensor electrodes; And

A processing system, the processing system

A sensor module configured to operate a plurality of sensor electrodes for capacitive sensing,

A reference voltage modulator configured to modulate the reference voltage rails of the processing system, and

And a receiver configured to simultaneously capture result signals from sensor electrodes to detect an input object while modulating the reference voltage rails.

In a second example of the input device of Example 1, each sensor electrode comprises at least one common electrode of the display device.

In a third example of the input device of Example 2, a plurality of sensor electrodes are arranged as a matrix of sensor electrodes on the same layer.

In a fourth example of the input device of Example 3, at least one grid electrode is disposed between at least two of the sensor electrodes in the same layer.

In a fifth example of the input device of Example 2, the input device further comprises a plurality of receiver electrodes, wherein the plurality of sensor electrodes comprises a plurality of transmitter electrodes.

In a sixth example of the input device of example 1, the input device further comprises a display, wherein the sensor electrodes are outside the display.

In a seventh example of the input device of example 1, the sensor module is disposed within an integrated circuit, wherein at least a portion of the reference voltage modulator is external to the integrated circuit.

In an eighth example of the input device of Example 1, the processing system further comprises a display module configured to update pixels in the display screen, wherein the display module is disposed within a first integrated circuit and at least a portion of the sensor module is a second The integrated circuit is disposed, and at least a portion of the reference voltage modulator is disposed outside the first and second integrated circuits.

In a ninth example of the input device of Example 1, the processing system further comprises a display module configured to update pixels in the display screen, wherein the display module is disposed within the first integrated circuit and at least of the sensor module and the reference voltage modulator. A portion is disposed within the second integrated circuit.

In a tenth example of the input device of Example 1, the processing system further comprises a display module configured to update pixels in the display screen, wherein the display module is disposed within the integrated circuit and at least a portion of the reference voltage modulator is external to the integrated circuit. Is in.

In an eleventh example of the input device of Example 1, the processing system,

A display module configured to update pixels in the display screen, configured as a timing controller, and disposed within the first integrated circuit; And

Further comprising a source driver configured to update the pixels based on signals received from the display module, wherein the source driver and the sensor module are disposed in a second integrated circuit, and at least a portion of the reference voltage modulator is It is placed outside the integrated circuits.

In a twelfth example of the input device of example 1, the reference voltage modulator and the receiver are arranged in the same integrated circuit, where the receiver is configured to modulate the reference voltage rails.

In a thirteenth example of the input device of Example 1, the reference voltage modulator includes a transmitter that generates a modulated signal to modulate the reference voltage rails.

In a fourteenth example of the input device of Example 1, the processing system further comprises a display module configured to update pixels in the display screen using reference voltage rails, wherein when updating the pixels, the reference voltage rails are not modulated. Maintained at non-DC voltages.

In the fifteenth example of the input device of Example 14, the input device is:

Further comprising a power management controller configured to provide a plurality of power rails using the reference voltage rails, wherein the power management controller is in a low-power state when the reference voltage modulates the reference voltage rails and the display module It is active when updating.

In a sixteenth example of the input device of Example 1, the input device further comprises a plurality of display electrodes, wherein the receiver is from both the display electrodes and the sense electrodes for performing capacitive sensing while modulating the reference voltage rails. It is configured to capture the resulting signals simultaneously.

In a seventeenth example of the input device of Example 1, the input device further comprises a display panel comprising a display screen and a backlight, wherein the reference voltage modulator is configured to modulate the reference voltage rails when the backlight and the display panel are turned off. do.

In an eighteenth example of the input device of Example 1, prior to modulating the voltage rails, the processing system is configured to electrically short the reference voltage rails from the at least one DC power supply.

In the 19th example of the input device of Example 18, the input device is:

Display source;

Display panel; And

Further comprising a high-speed data interface disposed on the same integrated circuit as the reference voltage modulator, the data interface is configured to communicate with the display source to receive display data for updating the display screen, the high-speed data interface is a reference voltage rail Is the portion of the unmodulated voltage domain that contains power voltage rails that remain coupled to the DC power source when they are electrically shorted from the DC power source.

In a twentieth example, the processing system,

A sensor module configured to drive a plurality of sensor electrodes to detect driving capacitiveness;

A reference voltage modulator configured to modulate reference voltage rails of a processing system, wherein prior to modulating the voltage rails, the processing system is configured to electrically short reference voltage rails from at least one DC power supply; And

And a receiver configured to capture resulting signals using sensor electrodes to detect an input object while modulating the voltage rails.

In the 21st example, the processing system of the 20th example,

Further comprising a display module configured to update pixels in the display screen using reference voltage rails, wherein when updating the pixels, the reference voltage rails are maintained at unmodulated DC voltages.

In a 22nd example, the processing system of the 21st example, the display module is configured to couple to a plurality of display electrodes for updating pixels, wherein the receiver is a display electrode for performing capacitive sensing while modulating the reference voltage rails. And simultaneously capture result signals from both the sensing electrodes and the sensing electrodes.

In the 23rd example, the processing system of the 20th example,

Further comprising a display module configured to update pixels in the display screen, wherein the display module is disposed on the integrated circuit along at least a portion of the sensor module.

In the 24th example, the processing system of the 20th example,

Further comprising a display module configured to update pixels in the display screen, wherein the display module is disposed in the first integrated circuit and at least a portion of the sensor module and the reference voltage modulator are disposed in the second integrated circuit.

In a 25th example, the processing system of the 20th example,

Further comprising a display module configured to update pixels in the display screen, wherein the display module is disposed in the first integrated circuit and at least a portion of the sensor module is disposed in the second integrated circuit, and at least a portion of the reference voltage modulator is It is disposed outside the first and second integrated circuits.

In example 26, the processing system of example 20,

Further comprising a display module configured to update pixels in the display screen, wherein the display module is disposed within the integrated circuit and at least a portion of the reference voltage modulator is external to the integrated circuit.

In Example 27, the processing system of Example 20,

A display module configured to update pixels in the display screen, configured as a timing controller, and disposed within the first integrated circuit; And

Further comprising a source driver configured to update the pixels based on signals received from the display module, wherein the source driver and the sensor module are disposed in a second integrated circuit, and at least a portion of the reference voltage modulator is It is placed outside the integrated circuits.

In a 28th example, in the processing system of the 20th example, prior to modulating the voltage rails, the processing system is configured to electrically short the reference voltage rails from the at least one DC power supply.

In a 29th example, the input device comprises: a plurality of sensor electrodes; And a processing system,

Each sensor electrode comprises at least one common electrode of the display device, the sensor electrodes being disposed on a common plane in the matrix array,

The processing system,

A sensor module configured to operate a plurality of sensor electrodes for capacitive sensing,

A reference voltage modulator configured to modulate the reference voltage rails of the processing system, and

And a receiver configured to capture resulting signals using sensor electrodes to detect an input object while modulating the voltage rails.

In a 30th example, in the input device of the 29th example, prior to modulating the voltage rails, the processing system is configured to electrically short the reference voltage rails from the at least one DC power source, the processing system comprising:

Further comprising a display module configured to update pixels in the display screen using reference voltage rails, wherein when updating the pixels, the reference voltage rails are maintained at unmodulated DC voltages.

In method 31, the method,

Driving a capacitive sensing signal on the plurality of sensor electrodes in the input device;

Electrically shorting the reference voltage rails from at least one DC power source;

Electrically shorting the reference voltage rails and then modulating the reference voltage rails; And

Capturing the resulting signals using the sensor electrodes to detect the input object while modulating the voltage rails.

The second group of example implementations may be described as follows:

In a first example, the input device,

A plurality of display electrodes;

A plurality of sensor electrodes; And

It includes a processing system, the processing system,

A reference voltage modulator configured to modulate reference voltage rails during a first period of time, the processing system comprising:

Updating the display using the display electrodes and reference voltage rails of the processing system for a second time period non-overlapping with the first time period, and

It is configured to capture result signals from the plurality of sensor electrodes during a first time period, and the reference voltage rails are maintained at constant voltages, which are not modulated during the first time period.

In a second example, the input device of the first example includes capacitively coupled reference voltage rails.

In a third example, the input device of the first example,

Further comprising source drivers coupled to the plurality of sensor electrodes, wherein the source drivers are configured to drive a capacitive detection signal onto the sensor electrodes for capacitive detection, and the capacitive detection signal is a modulated reference voltage Derived from rails.

In a fourth example of the input device of the third example, the source sensor electrodes are protected from at least one interfering signal when driven by a capacitive sensing signal derived from the modulated reference voltage rails.

In the fifth example, the input device of the third example,

Gate electrodes for updating the display; And

It further includes source electrodes for updating the display, wherein when driving the capacitive sensing signal onto the sensor electrodes, the gates electrodes are floating and the source electrodes are protected.

In a sixth example, the input device of the first example,

Further comprising a power management controller configured to receive unmodulated reference voltage rails when updating the display and convert the reference voltage rails to power voltages for supplying a display circuit in a display panel including the display.

In a seventh example of the input device of the sixth example, the power management controller is in a low-power state when the reference voltage modulator modulates the reference voltage rails and is in an active state when the display module updates pixels.

In the eighth example of the input device of the fourth example, the receiver is configured to simultaneously capture result signals from both the display electrodes and the sense electrodes for performing capacitive sensing.

In a ninth example, the input device of the first example,

Further comprising a backlight, wherein the reference voltage modulator is configured to modulate the reference voltage rails while the backlight and display are turned off.

In a tenth example, the input device of the first example,

Display source;

Display panel; And

Further comprising a high-speed data interface disposed on the same integrated circuit as the reference voltage modulator,

The data interface is configured to communicate with a display source to receive display data for updating the display, the high speed data interface is a power voltage rail that remains unmodulated when the reference voltage rails are modulated by a reference voltage modulator. Is the part of the unmodulated voltage domain that contains

In the eleventh example, the processing system,

A reference voltage modulator configured to modulate the reference voltage rails during a first time period;

A receiver configured to capture result signals for the plurality of sensor electrodes during a first period of time; And

A display module configured to update a display using a plurality of display electrodes and reference voltage rails during a second time period non-overlapping with the first time period,

Here, the reference voltage rails are maintained at DC voltages, which are not modulated during the second time period.

In a twelfth example of the eleventh example processing system, the reference voltage rails are capacitively coupled.

In a thirteenth example of the eleventh example processing system, the processing system,

Further comprising a power management controller configured to receive unmodulated reference voltage rails when updating the display and convert the reference voltage rails to power voltages for supplying a display circuit in a display panel including the display.

In a fourteenth example of the processing system of the thirteenth example, the power management controller is in a low-power state when the reference voltage modulator modulates the reference voltage rails and is in an active state when the display module updates pixels.

In a fifteenth example of the processing system of the eleventh example, the receiver is configured to simultaneously capture result signals from both the display electrodes and the sense electrodes for performing capacitive sensing.

In a sixteenth example of the eleventh example processing system, the processing system is configured to modulate the reference voltage rails while the backlight and display are turned off.

In a seventeenth example, the processing system of the eleventh example,

And a high speed data interface disposed on the same integrated circuit as the reference voltage modulator, the data interface configured to communicate with a display source to receive display data for updating the display, the high speed data interface being a reference voltage rail Is the portion of the unmodulated voltage domain that contains the power voltage rails that remain unmodulated when modulated by the reference voltage modulator.

In the 18th example, the method is,

Updating pixels in the display of the input device using reference voltage rails and a plurality of display electrodes during a first time period, wherein the reference voltage rails are maintained at DC voltages that are not modulated during the first time period. , The updating;

Modulating the reference voltage rails for a second period of time non-overlapping with the first period of time; And

Capturing resulting signals from the plurality of sensor electrodes based on modulating the reference voltage rails.

In a nineteenth example of the method of the eighteenth example, the input device is in a low power state for a second period of time, and the method comprises:

After detecting the input object based on the resulting signals:

Switching the input device from a low power state to an active state; And

And stopping modulating the reference voltage rails.

In the 20th example, the method of the 18th example,

Prior to modulating the reference voltage rails, further comprising electrically shorting the DC power supply from the reference voltage rails.

In a twenty-first example of the method of the eighteenth example, capturing the resulting signals comprises:

Simultaneously receiving individual result signals from the display electrodes and sensor electrodes, wherein the individual result signals are used to perform capacitive sensing.

A third group of example implementations may be described as follows:

In a first example, the input device,

A plurality of sensor electrodes; And

It includes a processing system, the processing system,

A reference voltage modulator configured to modulate a reference voltage used to provide power to a plurality of power sources,

A central receiver configured to simultaneously capture first result signals from the plurality of sensor electrodes when the reference voltage is being modulated, and

A plurality of local receivers each coupled to at least one of the sensor electrodes, the local receivers being configured to capture second result signals from the sensor electrodes,

The processing system is configured to mitigate the effect of the grounding condition on the second result signal using the first result signals.

In a second example, the input device of the first example,

The reference voltage further includes a controller configured to short the reference voltage from the DC power source while it is being modulated.

In a third example, the input device of the first example,

It further comprises a display/sensing panel comprising a plurality of sensor electrodes, a plurality of local receivers, and a plurality of display electrodes, wherein each of the sensor electrodes is only coupled to one of the local receivers.

In a fourth example of the input device of the first example, capturing the second result signals on local receivers occurs in parallel with capturing the first result signals on the central receiver when the reference voltage is modulated.

In a fifth example of the input device of the first example, the central receiver is configured to capture third result signals from the plurality of display electrodes while the reference voltage is being modulated, and the processing system is in a ground state on the second result signals. And the effect is mitigated using the third result signals.

In a sixth example of the input device of the first example, the ground state is: (i) a first capacitive coupling between the input object interacting with the input device and ground, and (ii) a second capacitance between the input device and ground. It is at least one of the sexual couplings.

In a seventh example of the input device of the first example, the processing system,

Further comprising a display module configured to update pixels in the display screen, wherein the display module and local receivers are disposed within a common integrated circuit.

In an eighth example of the input device of the first example, the processing system,

Further comprising a display module configured to update pixels in the display screen, wherein the display module is disposed within the first integrated circuit and at least a portion of the local receivers are disposed within the second integrated circuit.

In a ninth example of the input device of the first example, a plurality of sensor electrodes are arranged in a matrix array.

In a tenth example, the processing system,

A reference voltage modulator configured to modulate a reference voltage used to provide power to the plurality of power sources;

A central receiver configured to simultaneously capture first result signals from the plurality of sensor electrodes when the reference voltage is being modulated; And

A plurality of local receivers configured to capture second result signals from the plurality of sensor electrodes,

Here, the processing system is configured to mitigate the effect of the grounding state on the second result signals by using the first result signals.

In the eleventh example, the processing system of the tenth example,

Further comprising a controller configured to short the reference voltage from the DC power source while the reference voltage is being modulated.

In a twelfth example of the processing system of the tenth example,

It further comprises a power management controller comprising power sources, wherein the power sources are configured to provide power to the display.

In a thirteenth example of the processing system of the tenth example, the step of capturing the second result signals on local receivers occurs in parallel with the step of capturing the first result signals on the central receiver when the reference voltage is modulated.

In a fourteenth example of the processing system of the tenth example, the central receiver is configured to capture third result signals from the plurality of display electrodes while the reference voltage is being modulated, wherein the processing system has a ground applied to the second result signals. And configured to mitigate the effect of the state using the third result signals.

In a fifteenth example of the processing system of the tenth example, the ground state is: (i) a first capacitive coupling between the ground and the input object interacting with the chassis containing the processing system, and (ii) the chassis and the ground. At least one of the second capacitive couplings.

In the 16th example, the method is,

Modulating a reference voltage used to provide power to a plurality of power sources;

Simultaneously capturing first result signals from the plurality of sensor electrodes at the central receiver while modulating the reference voltage;

Capturing second result signals from sensor electrodes at a plurality of local receivers; And

And mitigating the influence of the grounding state on the second result signal by using the first result signals.

In the 17th example, the method of the 16th example,

And electrically isolating the reference voltage from the DC power supply while the reference voltage is being modulated.

In an eighteenth example of the method of the sixteenth example, the first result signals are captured at a central receiver in parallel with acquiring the second result signals at a plurality of local receivers.

In the 19th example of the method of the 16th example,

Simultaneously capturing third result signals from the plurality of display electrodes at the central receiver while modulating the reference voltage; And

The step of mitigating the influence of the grounding state on the second result signal using the third result signals.

Accordingly, in order to best describe the embodiments in accordance with the present technology and its specific application and to make the present technology available to those of ordinary skill in the art, the embodiments and examples disclosed herein have been presented. However, it will be appreciated by those skilled in the art that the foregoing description and examples have been presented for purposes of illustration and example only. The description as disclosed is not intended to be exhaustive or to limit the disclosure to the precise form disclosed.

In view of the above description, the scope of this disclosure is determined by the claims that follow.

Claims (10)

As an input device,
A plurality of sensor electrodes; And
Includes a processing system,
The processing system,
A sensor module configured to operate the plurality of sensor electrodes for capacitive sensing;
A reference voltage modulator configured to modulate reference voltage rails of the processing system while the input device is in a low power state; And
A receiver configured to simultaneously capture result signals from the sensor electrodes to detect an input object while modulating the reference voltage rails,
The receiver and the sensor electrodes are coupled to a common electrical node,
The processing system is configured to switch the input device from the low power state to an active state based on the captured result signals. The method of claim 1,
The input device, wherein each sensor electrode comprises at least one common electrode of the display device. The method of claim 2,
The input device, wherein the plurality of sensor electrodes are arranged as a matrix of sensor electrodes on the same layer. The method of claim 3,
An input device, wherein at least one grid electrode is disposed between at least two of the plurality of sensor electrodes of the same layer. The method according to any one of claims 2 to 4,
The input device further comprises a plurality of receiver electrodes,
The input device, wherein the plurality of sensor electrodes comprises a plurality of transmitter electrodes. The method according to any one of claims 1 to 5,
The input device further comprises a plurality of display electrodes,
Wherein the receiver is configured to simultaneously capture result signals from both the display electrodes and sense electrodes to perform capacitive sensing while modulating the reference voltage rails. The method according to any one of claims 1 to 6,
And prior to modulating the reference voltage rails, the processing system is configured to electrically disconnect the reference voltage rails from at least one DC power supply. As a processing system,
A sensor module configured to drive a plurality of sensor electrodes for capacitive sensing;
A reference voltage modulator configured to modulate reference voltage rails of the processing system while an input device comprising the processing system is in a low power state, wherein the processing system modulates the reference voltage rails before modulating the reference voltage rails. The reference voltage modulator configured to electrically disconnect from at least one DC power source; And
A receiver configured to simultaneously capture result signals using the sensor electrodes to detect an input object while modulating the reference voltage rails, wherein the receiver and the sensor electrodes are coupled to a common electrical node, the processing system And the receiver, configured to switch the input device from the low power state to an active state based on the captured result signals. As an input device,
A plurality of sensor electrodes, each sensor electrode comprising at least one common electrode of a display device, the sensor electrodes being disposed in a matrix arrangement on a common plane; And
Includes a processing system,
The processing system,
A sensor module configured to operate the plurality of sensor electrodes for capacitive sensing;
A reference voltage modulator configured to modulate reference voltage rails of the processing system while the input device is in a low power state; And
A receiver configured to capture result signals using the sensor electrodes to detect an input object while modulating the reference voltage rails,
The receiver and the sensor electrodes are coupled to a common electrical node,
The processing system is configured to wake up the input device from the low power state based on the captured result signals. As a method,
Driving a capacitive sensing signal on the plurality of sensor electrodes in the input device;
Electrically disconnecting the reference voltage rails from the at least one DC power source;
After electrically disconnecting the reference voltage rails, modulating the reference voltage rails while the input device is in a low power state;
Simultaneously capturing result signals using the sensor electrodes at a receiver to detect an input object while modulating the reference voltage rails, wherein the receiver and the sensor electrodes are coupled to a common electrical node. Capturing simultaneously; And
Based on the captured result signals, switching the input device from the low power state to an active state.

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