JP2016126765A - Modulating reference voltage to perform capacitive sensing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique for modulating a reference voltage to perform capacitive sensing.SOLUTION: This 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., Vand V). The input device includes 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 are then processed to determine if an input object is interacting with the input device.SELECTED DRAWING: Figure 2

Description

  [0001] Embodiments of the present invention generally relate to electronic devices, and more particularly to modulating a reference voltage to provide capacitive sensing.

  [0002] Input devices including proximity sensor devices (typically also referred to as touchpads or touch sensor devices) are widely used in various electronic systems. Proximity sensor devices typically include a sensing area often defined by a surface to determine the presence, position and / or movement of one or more input objects. Proximity sensor devices are used to form the interface of electronic systems. For example, proximity sensor devices are often used as input devices for large computing systems (eg, opaque touchpads that are integrated into or around a notebook or desktop computer). Proximity sensor devices are also often used in small computing systems (such as touch screens integrated in mobile phones).

  [0003] 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 a reference voltage rail of the processing system, and a reference voltage rail. A receiver configured to simultaneously acquire a result signal from the sensor electrode to detect an input object during modulation.

  [0004] Another embodiment described herein includes a sensor module configured to drive a plurality of sensor electrodes for capacitive sensing and a reference voltage configured to modulate a reference voltage rail of the processing system. And a processing system comprising a modulator configured to electrically disconnect the reference voltage rail from the at least one DC power source prior to modulating the voltage rail. The processing system also includes a receiver configured to obtain a result signal using the sensor electrode to detect the input object while modulating the voltage rail.

  [0005] Another embodiment described herein includes an input device comprising a plurality of sensor electrodes each including at least one common electrode of a display device, the sensor electrodes being arranged in a matrix array on a common plane. . 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 a reference voltage rail of a processing system, and a reference voltage rail And a receiver configured to obtain a result signal using the sensor electrode to detect an input object while modulating the signal.

  [0006] Another embodiment described herein is a method that includes driving capacitive sensing signals at a plurality of sensor electrodes of an input device and electrically disconnecting a reference voltage rail from at least one DC power source. . After electrically disconnecting the reference voltage rail, the method includes modulating the reference voltage rail. The method also includes obtaining a result signal using the sensor electrode to detect the input object while modulating the voltage rail.

  [0007] In order to provide a thorough understanding of the features of the invention, the disclosure briefly outlined above will now be described in detail with reference to a few embodiments illustrated in the accompanying drawings. However, it should be noted that the accompanying drawings show only typical embodiments of the present disclosure, and therefore the present disclosure is not intended to limit the scope of the present invention, as other equally effective embodiments are acceptable. I want to be.

1 is a block diagram of an example system with an input device according to an embodiment of the invention. FIG. 6 illustrates an input device that modulates a reference voltage rail for capacitive sensing according to one embodiment described herein. FIG. FIG. 6 illustrates an input device that modulates a reference voltage rail for capacitive sensing according to one embodiment described herein. FIG. FIG. 6 illustrates an input device that modulates a reference voltage rail for capacitive sensing according to one embodiment described herein. FIG. 2 is a circuit diagram of a reference voltage modulator according to one embodiment described herein. FIG. 6 is a flow chart for wake up an input device from a low power state using a modulated reference voltage rail, according to one embodiment described herein. FIG. 4 illustrates an exemplary electrode configuration for performing capacitive sensing according to one embodiment described herein. FIG. Fig. 4 illustrates an input device for detecting a noise signal or a communication signal from an active input object according to one embodiment described herein. FIG. 4 is a circuit diagram of a receiver that obtains a result signal to identify noise or communication signals according to one embodiment described herein. 6 is a flowchart for identifying noise or communication signals using capacitive sensing according to one embodiment described herein. Fig. 4 illustrates various capacitances between an input device and an environment according to one embodiment described herein. FIG. 6 illustrates an input device that modulates a reference voltage rail for capacitive sensing according to one embodiment described herein. FIG. It is a flowchart for reducing the effect | action of the low grounding mass state by one Embodiment described here. Fig. 4 illustrates various capacitances between an input device and an environment according to one embodiment described herein. 6 is a chart showing the results of reducing the effect of a low ground mass state according to one embodiment described herein.

  [0023] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the drawings. Elements disclosed in one embodiment may be conveniently used in other embodiments without specific instruction. It should be understood that the drawings referred to herein are not drawn to scale unless otherwise indicated. Also, the drawings are often simplified and details and components are omitted for clarity of presentation and description. The drawings and discussion serve to explain the following principles, where like designations denote like elements.

  [0024] The following detailed description is merely exemplary in nature and is not intended to limit the disclosure or the application and use thereof. Furthermore, there is no limitation to the theory expressed or implied in the foregoing technical field, background, brief summary or the following detailed description.

[0025] Various embodiments of the present invention provide an input device with a reference voltage modulator that modulates a reference voltage rail when performing capacitive sensing. In one embodiment, the reference voltage rail is coupled to a DC power source that provides power to operate a panel with a display screen integrated with the touch sensitive area. Prior to performing capacitive sensing, the input device isolates the DC power source from the reference voltage rail and uses the reference voltage rail to modulate the rails, V _DD and V _GND . For example, the reference voltage modulator changes the rail voltage in the same increment. 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, the separation of the reference voltage rail does not require the rail to be physically disconnected from the power source. Rather, the reference voltage rail is inductively or capacitively coupled to the power supply.

  [0026] In one embodiment, the reference voltage rail is modulated (and capacitive sensing is performed) when the input device is in a low power state. In one example, the display / sense panel (and the backlight, if any) is turned off and does not consume power. Nevertheless, by sensing the reference voltage rail, capacitive sensing can be performed using the display / sensor panel display and sensor electrodes. In other words, by modulating the reference voltage rail, an input object (eg, a finger) that is capacitively coupled to the display and sensor electrodes of the panel can be detected by measuring the capacitance change. When an input object is detected, the input device wakes up and switches from a low power state to an active state.

  [0027] In one embodiment, when performing capacitive sensing by modulating the reference voltage rail, the display and sensor electrodes are treated as one capacitive pixel or electrode. Thus, by measuring the resulting signal from the display and sensor electrodes, the input device determines whether the input object is approaching the panel, but determines the specific location that the input object is touching or hovering. It is not a thing. Rather, when active, the input device performs a more granular form of capacitive sensing technology that identifies a particular location of the input object in the sensing area. When performing capacitive sensing in the active state, the input device drives the DC voltage of the reference voltage rail, i.e., the rail is not modulated, or the rail is modulated but senses it by sensing current or charge. There is no need to do it.

  [0028] Referring to the drawings, FIG. 1 is a block diagram of an exemplary input device 100 according to an embodiment of the present invention. Input device 100 is configured to provide input to an electronic system (not shown). As used herein, the term “electronic system” (or “electronic device”) broadly refers to a system that can electrically process information. Some non-limiting examples of electronic systems include personal computers of all sizes and shapes, such as desktop computers, laptop computers, netbook computers, tablets, web browsers, e-book readers, and personal digital assistants (PDAs) including. Additional exemplary electronic systems include a composite input device such as an input device 100 and a physical keyboard that includes individual joysticks or key switches. Yet another exemplary electronic system includes peripheral devices such as data input devices (including remote controls and mice) and data output devices (including display screens and printers). Other examples include remote terminals, kiosks, and video game machines (eg, video game consoles, portable game machines, etc.). Other examples include communication devices (including mobile phones such as smart phones) and media devices (recorders, editors and players such as televisions, set top boxes, music players, digital photo frames, and digital cameras). ). In addition, the electronic system is a host or slave to the input device.

[0029] The input device 100 may be implemented as a physical part of the electronic system or may be physically separated from the electronic system. Input device 100 communicates with parts of the electronic system, as appropriate, using one or more of the following: buses, networks, and other wired or wireless interconnects. For example, I ² C, SPI, PS / 2, Universal Serial Bus (USB), Bluetooth (registered trademark), RF, and IRDA are included.

  In FIG. 1, the input device 100 is also referred to as a proximity sensor device (“touch pad” or “touch sensor device”) configured to sense input provided by one or more input objects 140 in the sensing region 120. Often referred to as). The normative input object includes a finger and a stylus as shown in FIG.

  [0031] The sensing area 120 is on, around, in and / or near the input device 100 where the input device 100 can detect user input (eg, user input provided by one or more input objects 140). Surround the space. The size, shape and position of the specific sensing area vary widely from embodiment to embodiment. In some embodiments, the sensing region 120 extends from the surface of the input device 100 into a space in one or more directions until the signal-to-noise ratio prevents sufficiently accurate object detection. The distance that this sensing region 120 extends in a particular direction is in various embodiments less than 1 mm, several mm, cm or more, and varies significantly with the type of sensing technique used and the desired accuracy. Thus, in some embodiments, the input device 100 surface is non-contacting, the input device 100 is in contact with the input surface (eg, touch surface), the input surface of the input device 100 combined with a certain amount of applied force or pressure Input, and / or combinations thereof are sensed. In various embodiments, the input surface is formed by the surface of the casing in which the sensor electrode is present, a face sheet attached to the sensor electrode, or any casing, etc. In some embodiments, the sensing area 120 is rectangular when projected onto the input surface of the input device 100.

  [0032] The input device 100 may detect user input in the sensing area 120 using a combination of sensor components and sensing technology. The input device 100 includes one or more sensing elements for detecting user input. As a number of non-limiting examples, the input device 100 uses capacitive, elastic, resistive, inductive, magnetic, acoustic, ultrasonic, and / or optical techniques.

  [0033] Certain embodiments are configured to provide an image that spans a one-dimensional, two-dimensional, three-dimensional or higher dimensional space. Some embodiments are configured to provide a projection of input along a particular axis or plane.

  [0034] In a resistive embodiment of the input device 100, the flexible conductive first layer is separated from the conductive second layer by one or more spacer elements. During operation, one or more voltage gradients are formed across the layers. When the flexible first layer is pressed, it is sufficiently deflected to create an electrical contact between the layers, resulting in a voltage output reflecting the contact point (s) between the layers. These voltage outputs are used to determine position information.

  [0035] In an inductive embodiment of the input device 100, one or more sensing elements pick up the loop current induced by the resonant coil or pair of coils. A combination of current magnitude, phase and frequency can be used to determine position information.

  [0036] In certain capacitive embodiments of the input device 100, a voltage or current is applied to generate an electric field. Neighboring input objects change the electric field and cause a detectable change in the capacitive coupling that is detected as a change in voltage, current, etc.

  [0037] Certain capacitive embodiments use an array of capacitive sensing elements or other granular or irregular patterns to generate the electric field. In certain capacitive embodiments, individual monitoring elements are ohmic shorted to form large sensor electrodes. Some capacitive embodiments use a resistive sheet that is a uniform resistance.

  [0038] Certain capacitive embodiments use a "self-capacitance" (or "absolute capacitance") sensing method that is based on a change in capacitive coupling between the sensor electrode and the input object. In various embodiments, an input object near the sensor electrode changes the electric field near the sensor electrode, thus changing the measured capacitive coupling. In some embodiments, the absolute capacitance sensing method operates by modulating the sensor electrode relative to a reference voltage (eg, system ground) and detecting capacitive coupling between the sensor electrode and the input object. To do.

  [0039] Certain capacitive embodiments use a "mutual capacitance" (or "transcapacitance") sensing method based on changes in capacitive coupling between sensor electrodes. In various embodiments, an input object near the sensor electrodes changes the electric field between the sensor electrodes and thus changes the measured capacitive coupling. In one embodiment, the transcapacitance sensing method includes one or more transmitter sensor electrodes (also “transmitter electrodes” or “transmitters”) and one or more receiver electrodes (“receiver electrodes” or “receivers”). It also operates by detecting the capacitive coupling between them. The transmitter sensor electrode is modulated with respect to a reference voltage (eg, system ground) to transmit a transmitter signal. The receiver sensor electrode is held substantially constant relative to the reference signal to facilitate reception of the result signal. The result signal includes actions corresponding to one or more transmitter signals and / or one or more environmental interference sources (eg, other electromagnetic signals). The sensor electrode may be a dedicated transmitter or receiver, or may be configured to perform both transmission and reception.

  In FIG. 1, the processing system 110 is shown as part of the input device 100. The processing system 110 is configured to operate the input device 100 hardware to detect the input of the sensing area 120. The processing system 110 includes some 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 a signal at a transmitter sensor electrode and / or a receiver circuit configured to receive a signal at a receiver sensor electrode. I have. In certain embodiments, the processing system 110 also includes electronically readable instructions such as firmware code, software code, and the like. In some embodiments, the components that make up the processing system 110 are placed together, for example, in the vicinity of the sensing element of the input device 100. In other embodiments, the components of processing system 110 are physically separate from one or more components in proximity to the sensing element of input device 100 and one or more components elsewhere. For example, the input device 100 is a peripheral device coupled to a desktop computer, and the processing system 110 is software configured to be executed in a central processing unit of the desktop computer, and one separate from the central processing unit. Has more than one IC (possibly with associated firmware). As another example, the input device 100 may be physically integrated into the phone, and the processing system 110 may include circuitry and firmware that are part of the main processor of the phone. In some embodiments, the processing system 110 implements the input device 100 exclusively. In other embodiments, the processing system 110 also performs other functions such as operating a display screen, driving haptic actuators, and the like.

  [0041] The processing system 110 is implemented as a set of modules that handle different functions of the processing system 110. Each module includes circuitry, firmware, software, or combinations thereof that are part of processing system 110. In various embodiments, the modules may be used in different combinations. An exemplary module reports hardware operating modules for operating hardware such as sensor electrodes and display screens, data processing modules for processing data such as sensor signals and position information, and reporting information. And a report module for. Yet another exemplary module includes a sensor operation module configured to operate a sensing element to detect an input, an identification module configured to identify a gesture such as a mode switching gesture, and an operation mode. And a mode switching module for switching.

  [0042] In certain embodiments, the processing system 110 causes one or more actions to be performed in direct response to user input (or lack of user input) in the sensing area 120. Example actions include switching modes of operation and GUI actions such as cursor movement, selection, menu navigation, and other functions. In some embodiments, the processing system 110 may provide information regarding input (or missing input) such as if there is a central processing system of the electronic system that is separate from the electronic system (eg, separate from the processing system 110). To the central processing system). In certain embodiments, certain portions of the electronic system process information received from the processing system 110 to affect user input, facilitating a full range of actions including, for example, mode switching actions and GUI actions.

  [0043] For example, in some embodiments, the processing system 110 operates a sensing element of the input device 100 to generate an electrical signal that represents an input (or missing input) in the sensing region 120. The processing system 110 performs an appropriate amount of processing on the electrical signal to generate information for the electronic system. For example, the processing system 110 digitizes analog electrical signals obtained from sensor electrodes. As another example, the processing system 110 performs filtering or other signal conditioning. As yet another example, the processing system 110 subtracts or otherwise takes into account the information so that the information reflects the difference between the electrical signal and the baseline. As yet another example, the processing system 110 determines position information, confirms input as a command, confirms handwriting, and so on.

  [0044] As used herein, "positional information" broadly encompasses absolute position, relative position, velocity, acceleration, and other types of spatial information. Exemplary “zero dimension” position information includes near / far or contact / non-contact information. Exemplary “one-dimensional” position information includes a position along an axis. Exemplary “two-dimensional” position information includes motion in a plane. Exemplary “three-dimensional” position information includes instantaneous or average velocity in space. Yet another example includes other representations of spatial information. Historical data relating to one or more types of position information is also determined and / or stored, including, for example, historical data that tracks position, movement, or instantaneous speed over time.

  [0045] In certain embodiments, the input device 100 is implemented with additional input components operated by the processing system 110 or other processing systems. These additional input components provide redundant or other functions for input in the sensing area 120. FIG. 1 shows a button 130 near the sensing area 120 that can be used to facilitate selection of an item using the input device 100. Other types of additional input components include sliders, balls, wheels, switches, etc. Conversely, in certain embodiments, the input device 100 may be implemented without other input components.

  [0046] In certain embodiments, the input device 100 comprises a touch screen interface and the sensing area 120 overlaps at least a portion of the active area of the display screen. For example, the input device 100 includes a substantially transparent sensor electrode that overlies a display screen and provides a touch screen interface for the associated electronic system. The display screen is any type of dynamic display that can display a visual interface to the user, and any type of light emitting diode (LED), organic LED (OLED), cathode ray tube (CRT), liquid crystal display (LCD), Includes plasma, electroluminescence (EL), or other display technologies. The input device 100 and the display screen share physical elements. For example, in some embodiments, several identical electrical components are used for display and sensing. As another example, the display screen may be partially or fully operated by the processing system 110.

  [0047] Although numerous embodiments of the present invention will be described with respect to a fully functional device, it is to be understood that the mechanisms of the present invention can be distributed as various forms of program products (eg, software). For example, the mechanism of the present invention may be on an information retention medium readable by an electronic processor (eg, a non-transitory computer readable and / or recordable / writable information retention medium readable by processing system 110). Implemented and distributed as a software program. Furthermore, embodiments of the present invention apply equally regardless of the specific type of media used to perform the distribution. Non-transitory electronically readable media include various disks, memory sticks, memory cards, memory modules, and the like. Electronically readable media are based on flash, optical, magnetic, holographic, or other storage technologies.

[0048] FIG. 2 illustrates an input device 200 that modulates a reference voltage rail for capacitive sensing in accordance with one embodiment described herein. The input device 200 includes a power source 202, a host 204, a processing system 110, a backlight 232, and a display / sensing panel 234. In one embodiment, power supply 202 is a DC power supply that outputs at least two reference voltages -V _DD and V _GND that provide power to processing system 110, backlight 232, and display / sense panel 234. The power source 202 is a battery or a power converter that plugs 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 chassis ground 208 to indicate that this is the reference voltage for the input device 200. In contrast, other power domains of input device 200 include a local ground reference (eg, local ground 216) that may be the same voltage as chassis ground 208 or a different voltage. For example, as described below, in one time period, local ground 216 may be the same voltage as chassis ground 208, but in other time periods, it is modulated by being driven to a different voltage.

[0049] In one embodiment, host 24 represents a general system of input device 200 that performs a number of functions, such as making a telephone call, wirelessly transmitting data, running an operating system or application, and the like. The host 204 includes a display source 206 that provides the updated data frame to the processing system 110. For example, the display source 206 is a graphics processing unit (GPU) that transmits pixel or frame data to the processing system 110 to update the display of the display / sense panel 234. In order to provide updated display data, the display source 206 is coupled to the processing system 110 via a high speed link 244 that transmits data at a rate of 1 Gbit / s or higher at all frame rates. For example, the display source 206 uses a DisplayPort ^™ (eg, eDP) or MIPI® display interface to communicate display data over the high speed link 244. This interface includes a single pair (eg, differential) or multi-wire physical connection, eg, 3-wire signaling, shared clock, multiple links with embedded clock, 3-level signaling, etc.

  [0050] The processing system 110 includes switches 210, 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 control signal 218, timing controller 220 opens and closes switches 210, 212, thereby electrically connecting and disconnecting reference voltage rail 211 to power supply 202. Although shown as an ohmic connection, in other embodiments, the reference voltage rail 211 is capacitively or inductively coupled to the power supply 202. In any case, the switches 210, 212 can be used to disconnect the reference voltage rail 211 from the power source 202 while the modulation signal 228 can be used to modulate the voltage rail.

  [0051] When the switches 210, 212 close, the power source 202 charges the bypass capacitor 214. When the switches 210, 212 are opened, the charge stored in the bypass capacitor 214 is used to energize the reference voltage rail 211, which is then used to various components within the input device 200 (e.g., power management). The controller 230, the backlight 232, or the panel 234) is energized. In one embodiment, the timing controller 220 uses the control signal 218 to periodically open and close the switches 210, 212 and maintain a substantially constant average voltage across the capacitor 214 and the rail 211. Alternatively, the timing controller 220 modulates the reference voltage rail 211 using the signal 228 while a separate control element (eg, flyback inductor) controls the voltage across the capacitor 214.

  [0052] 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 / sense panel 234, and more particularly, to the sensor electrode 242 of the panel 234 either directly or through the modulation signal 228. Using the sensor electrode 242, the sensor module 222 performs capacitive sensing in the sensing region 120 shown in FIG. As described above, the sensor module 222 uses self-capacitance, mutual capacitance, or a combination thereof to identify a particular location in the sensing area 120 where the input object contacts or hoveres.

  [0053] Display module 224 is coupled to display circuit 236 (eg, source driver and gate selection logic) and display electrode 240 (eg, source electrode, gate electrode, common electrode) to update the display of panel 234. . For example, based on display data received from the display source 206, the display module 224 uses the gate electrode to iterate through the rows of the display and updates each display pixel in the selected row using the source electrode. Thus, the display module 224 thus receives the updated display frame from the host 204 and updates (or refreshes) the individual pixels of the display / sense panel 234 accordingly.

[0054] The reference voltage modulator 226 outputs a modulation signal 228 that modulates the reference voltage rail 211. In one embodiment, the reference voltage modulator 226 modulates the voltage rail 211 only when it is disconnected from the power source 202 (ie, only when the switches 210, 212 are open). In doing so, the modulation signal 228 enables the reference voltage rail 211 to be modulated with respect to the output of the power supply 202, ie, V _DD and V _GND . If the power supply 202 is not electrically disconnected, V _DD and V _GND are shorted by the modulation signal 228 when the reference voltage rail 211 is modulated, which depends on the power supplied by the power supply 202. Other components of the input device 200 may behave unpredictably or inappropriately. For example, the host 204 (or other component not shown in the input device 200) may use the power source 202 to energize that component. The host 204 is designed to operate with an unmodulated power supply, so that if the modulated signal 228 is not electrically isolated from the power supply 202, the signal 228 has a negative effect on the host 204. .

[0055] In one embodiment, the modulation signal 228 modulates the reference voltage rail by increasing or decreasing the voltage of the reference voltage rail in an individual quantitative or periodic manner. In one example, the modulation signal 228 causes the same or similar voltage changes in 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 modulation signal adds 1V voltage swing to both rails, voltage rail 211A changes from 5 to 3V, while voltage rail 211B Vary between -1 and 1V. Nevertheless, the voltage difference between the rails 211 (ie, 4V) remains the same. Further, the modulated signal 228 is a periodic signal (eg, a sine wave or a square wave) or an aperiodic signal that is not modulated using a repetitive signal. In one embodiment, the capacitive sensing measurement is demodulated to match the modulation waveform of the modulation signal 228.

  [0056] By modulating the reference voltage rail 211 relative to the chassis ground, from the point of view of the processing system 110, the outside world and the input object coupled to the chassis appear to have a voltage signal being modulated. That is, for the energized system in processing system 110, its voltage is stable and the rest of the external environment is modulated and not coupled to the input object near panel 234 and its modulated reference voltage rail 211. It appears to include other components of the input device 200. One effect of modulating the reference voltage rail 211 is that all components coupled to the rail 211 are modulated by the modulation signal 228. Thus, it is not necessary to drive individual modulation signals at the display electrodes 240, display circuit 236, or power management controller 230 to protect those electrodes, and therefore they do not interfere with capacitive sensing. In other words, the voltage difference between the electrodes used to perform capacitive sensing and the various components of the display panel 234 does not change. Thus, even if the electrodes and components of panel 234 are capacitively coupled, this coupling capacitance affects the resulting signal generated at the electrodes. In addition, standard components can be used, i.e., the display circuit 236 and the power management controller 230 do not need to be changed to provide protection.

  [0057] The power management controller 230 (eg, one or more power management integrated circuits (PMICs)) provides various voltages for energizing the display circuit 236 and the backlight 232 of the display / sense panel 234 via the panel power supply 231. give. The power management controller 230 includes a plurality of different power supplies that supply various voltages (eg, TFT gate voltages VGH, VHL, source voltage, VCOM, etc.). To generate the various voltages, the power supply uses an inductive boost circuit or capacitive charge pump to convert the DC voltage provided by the reference voltage rail 211 to the DC voltage desired by the backlight 232 or panel 234 circuit. It is a switching power supply that changes to The power supply also includes a buck circuit that efficiently energizes a low voltage digital circuit such as a gigabit serial link.

  [0058] In one embodiment, the reference voltage modulator 226 modulates the reference voltage rail 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 consumes 1 to 3 W when turned on, while the display module 224 and the display circuit 236 consume 0.5 to 1 W. In contrast, the sensor module 222 consumes 50 to 150 mW when performing capacitive sensing. Thus, power consumption can be significantly reduced if both the backlight 232 and the display module 224 are disabled when in a low power state. In one embodiment, the backlight 232 and the display module 224 are not energized while the reference voltage rail 211 is modulated.

  [0059] However, when the sensor and display modules 222, 224 are located on the same integrated circuit, the display control signal 233 is used to deactivate the display module 224 and the sensor module 222 and sensor control signal 235 are used. It is still impossible to carry out capacitive sensing. In this example, the input device relies on capacitive sensing performed by sensor module 222 to determine when to wake up from a low power condition (ie, determine when a user's finger approaches panel 234). In some cases, the display module 224 must also be active, meaning that the input device 200 does not benefit from the power savings that render the display module 224 inactive. In contrast, the input device 200 shown in FIG. 2 can perform capacitive sensing without energizing the isolated sensor module 222 when in a low power state, and thus the sensor module 222 and the display module. Benefits can be gained from power savings that can disable both 224. Accordingly, 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 each be disabled.

[0060] To perform capacitive sensing in a low power state when the sensor module 222 is disabled, in one embodiment, the reference voltage modulator 226 modulates at least one of the voltage rails 211. It includes circuitry for obtaining the resulting signal, ie the resulting signal, from the display and sensor electrodes 240,242. To that end, the reference voltage modulator 226 includes a separate receiver (not shown in FIG. 2) for measuring the resulting signal. In addition, the reference voltage modulator 226 has other circuits such as a filter (analog or digital) and an analog / digital converter (ADC) to sample the resulting signal. Based on measuring the change in coupling capacitance 246 between the input object 140 and the display / sensing panel 234, the input device 200 can detect the proximity of the input object near or in contact with the panel 234. In one embodiment, the result signal is obtained from both the display electrode 240 and the sensor electrode 242 simultaneously. Display and sensor electrodes 240, 242 are coupled to reference voltage rail 211 by panel 234. For example, the display and sensor electrodes 240, 242 are coupled to the power management controller 230, which is power for display update (eg, gate line voltage, V _com voltage, source voltage) and power for capacitive sensing. (E.g., a voltage to a power receiving device coupled to each sensor electrode 242). The power management controller 230 then receives that power via the reference voltage rail 211. Accordingly, the display and sensor electrodes 240, 242 (and other components of the panel 234) are coupled to a common electrode node with the reference voltage modulator 226 (ie, the same electrical where the modulation signal 228 is coupled to the voltage rail 211B). Node). Thus, when modulating the reference voltage rail 211, this modulates the power supply of the power management controller 230, then modulates various components of the panel 234, such as the display and sensor electrodes 240, 242 and the input device 200. Allows user input to be measured.

  [0061] Since the reference voltage modulator 226 is also coupled to this common node, the modulator 226 simultaneously obtains a result signal from the display and sensor electrodes 240, 242 when modulating the reference voltage rail 211. In other words, the reference voltage modulator 226 does not have to separately acquire the result signal from the various electrodes of the panel 234 at different time periods, but rather acquires the combined result signal from all the combined electrodes in parallel. To do. By acquiring the result signal simultaneously, the panel 234 can be thought of as a single large capacitive pixel or electrode. As the input object approaches a portion or position of the panel 234, the display of that portion and the sensor electrodes 240, 242 generate a result signal indicative of the change in capacitance (eg, self-capacitance) caused by the proximity of the input object. Thus, in one embodiment, by evaluating the resulting signal obtained by the reference voltage modulator 226, the input device 200 can determine whether the input object approaches the panel 234. However, since the panel is a single capacitive electrode (rather than a plurality of individual capacitive electrodes or pixels), the device 200 cannot identify the particular portion or position of the panel 234 where the input object is located. .

  [0062] In one embodiment, rather than using both display and sensor electrodes 240, 242 to perform capacitive sensing when modulating reference voltage rail 211, reference voltage modulator 226 includes display electrodes. The result signal is acquired from only 240 or only from the sensor electrode 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 particular position of the object in the panel 234.

  [0063] When an input object is detected, the input device 200 switches from a low power state to an active state in which a modulated signal is received during the display update time. For example, the input device 200 can operate the sensor module 222 to perform different capacitive sensing techniques. Unlike capacitive sensing performed using reference voltage modulator 226, this capacitive sensing technique logically divides the sensing area of panel 234 into a plurality of capacitive pixels. By determining which capacitive pixel (s) the associated capacitance has been changed by the input object, the input device determines the specific location or area of the panel 234 that the input object will touch or hover. Can do. As described above, the sensor module 222 can use self-capacitance sensing, mutual capacitance sensing, or a combination thereof to identify the position of the input object in the sensing area.

  [0064] In one embodiment, the reference voltage rail 211 is permanently isolated (eg, inductively or capacitively) from the power source 202 and thus selectively disconnected from the power source 202 before being modulated as described above. Need to be done. Rather, the processing system 110 and the display / sensing panel 234 are inductively coupled to separate individual power supplies (eg, separate batteries or power supplies) coupled to a reference voltage rail 211 that energize only those components. Charged capacitor). Thus, the reference voltage modulator 226 needs to ensure that the modulation of the voltage rail 211 does not negatively affect other components in the input device 200, for example when level translation or isolation at the communication interface is important. Rather, these voltage rails 211 can be modulated for capacitive sensing.

  [0065] The components of the processing system 110 may be arranged in a number of different configurations on one or more integrated circuits (chips). In one embodiment, sensor module 222, display module 224, and reference voltage modulator 226 are located on the same integrated circuit. In one embodiment, sensor module 222 is located on a different integrated circuit than reference voltage modulator 226. In another embodiment, sensor module 222, display module 224, and reference voltage modulator 226 are arranged in three separate integrated circuits. In another embodiment, sensor module 222 and reference voltage modulator 226 are located on the same integrated circuit, while display module 224 is located on a separate integrated circuit. Further, in one embodiment, the display module is disposed on one integrated circuit, while the sensor module 222 and at least a portion of the display circuit 236 (eg, source driver, mux or TFT gate driver) are the second integrated circuit. And a reference voltage modulator 226 is disposed on the third integrated circuit.

  [0066] In one embodiment, the processing system 110 comprises an integrated circuit that includes a power management controller 230, a timing controller 220, and a high speed link 244 coupled to the host 204. The integrated circuit also includes a source driver and receiver for performing display updates and capacitive sensing. Further, the integrated circuit is not located on a different substrate, but on the same substrate that supports the display / sense panel 234. The common substrate includes traces that couple the integrated circuit to the display and sensor electrodes 240,242.

  [0067] Furthermore, some displays (eg, LEDs or OLEDs) do not require a backlight. Nevertheless, capacitive sensing is performed using the reference voltage rail modulation technique described above.

[0068] FIG. 3 illustrates an input device 300 that modulates a reference voltage rail to provide capacitive sensing according to one embodiment described herein. Input device 300 includes a voltage regulator 315 to control and maintain rail voltages V _DD and V _GND provided by a power source (not shown). In one embodiment, the voltage regulator 315 may be replaced with a battery and / or the power controller 230 separates the modulated power domain 310 from the unmodulated power domain 305. Similar to the input device 200, the device 300 includes a timing controller 220 that outputs control signals 330A and 330B for controlling the switches 210 and 212 (ie, transistors). As described above, before modulating the reference voltage rail 211 (V _{DD_MOD} and V _{GND_MOD} ), the timing controller 220 opens the switches 210, 212 to electrically _connect the reference voltage rail 211 from the reference voltages V _DD and V _GND . Disconnect.

[0069] When the reference voltage rail 211 is electrically isolated from the reference voltages V _DD and V _GND , the input device 300 has two separate power domains: an unmodulated power domain 305 and a modulated power domain 310. Unmodulated power domain 305 includes components on the left side of dashed line 301, while modulated power domain 310 includes components on the right side of dashed line 301. The components of unmodulated power domain 305 operate using unmodulated DC reference voltages V _DD and V _GND , while the components of modulated power domain 310 use modulated reference voltages V _{DD_MOD} and V _{GND_MOD} of reference voltage rail 211. Use and work. As described above, the reference voltage rail 211 is modulated by the modulation signal 228 generated by the reference voltage modulator 226. For example, modulated signal 228 is driven to a voltage that is less than V _DD / 2, which is the input voltage of receiver 325. In one embodiment, the reference voltage modulator is located on the power management controller 230 or source driver rather than on the timing controller 220 as shown.

  [0070] As illustrated, the timing controller 220 includes a high-speed data interface 320 (eg, eDP or MIPI standard interface) in the unmodulated power domain 305. Accordingly, 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 the display module are also in the modulated power domain 310. Further, although the reference voltage modulator 226 is shown as being in the modulated power domain 310, the modulator 226 generates a modulated signal 228 for chassis ground in the unmodulated power domain 305, so that it is unmodulated. It may be considered to be in the power domain 305. The communication module further provides a modulated signal 228 and power domain isolation control 330.

  [0071] By leaving the high-speed data interface 320 in the unmodulated power domain 305, the timing controller 220 can communicate directly with the host 204. That is, the data interface 320 and the host 204 are both in the unmodulated power domain 305, but can transmit data signals directly. In contrast, if the interface 320 is in the modulated power domain 310 and operates using the modulated reference voltage, the interface 320 does not substantially increase cost, power, and design time, and the host 204 The data signal received from cannot be detected and identified. Although not shown, the timing controller 220 includes a level shifter that allows the high-speed data interface 320 to communicate with other modules in the timing controller 220. For example, upon receiving updated display data from the host 204, the high speed data interface 320 uses a level shifter when transmitting display data to display modules in the modulated power domain 310.

  [0072] In another embodiment, the entire timing controller 220 is in the modulated power domain 310. Individual communication modules are communicatively coupled between the host 204 and the controller 220 to communicate with the host 204. For example, the communication module is arranged in an integrated circuit separate from the timing controller 220. The communication module comprises one or more level shifters that allow data signals to be transmitted to the timing controller 220 in the modulated power domain 310 and data signals received from the timing controller 220 to be transmitted to the host 204 in the unmodulated power domain 305. Yes.

  [0073] The reference voltage modulator 226 includes a receiver 325 that obtains a result signal from the display and sensor electrodes of the panel 234 when modulating the reference voltage rail 211. The receiver 325 modulates the rail 211 using the same electrical connection used by the modulation signal 228 and also obtains the result signal. That is, the reference voltage modulator 226 transmits the modulation signal 228 using the same port and obtains the result signal from the display and sensor electrodes of the display / sense panel 234. Alternatively, the reference voltage modulator 226 receives the signal using only the display / sense panel 234 while the modulated signal 228 is applied to the reference electrode by another component (eg, source driver or power management controller 230). Supplied.

[0074] In input device 300, power management controller 230 includes a plurality of power supplies 335 that output a plurality of different DC voltages to panel 234 via link 340. In order to generate the various voltages, the power supply 335 uses the voltages provided by the reference voltage rail 211 (ie, V _{DD_MOD} and V _{GND_MOD} ) to the voltages required for the components of the panel 234, eg, V _GH , V _GL , A switching power supply that uses an inductive boost circuit or capacitive charge pump to switch to VCOM, etc. In one embodiment, reference voltage modulator 226 modulates reference voltage rail 211 and power management controller 230 disables power supply 335 (eg, the input device is in a low power state). However, when the input device 300 performs display update or capacitive sensing, the power supply 335 serves to supply DC power to the panel 234 when the voltage rail 211 is not modulated.

  [0075] FIG. 4 illustrates an input device 400 that modulates a reference voltage rail for capacitive sensing according to one embodiment described herein. In contrast to the input device 300 of FIG. 3, the input device 400 includes a reference voltage modulator 410 that does not obtain a result signal 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 located in the power management controller 230. However, the receiver 410 is not disposed in the modulator 410. Rather, the receiver 325 is located external to the modulator 410 of the timing controller 220 (but can be located anywhere within the processing system 110, such as a separate integrated circuit). Thus, in this embodiment, the electrical path used to obtain the result signal is different from the electrical path used to drive the modulation signal 228. Further, for example, if a capacitive signal is provided by capacitor 405, no direct ohmic contact between receiver 325 and modulation rail 211 is required as shown here. 3 and 4 show that the result signal can be acquired via any one of the voltage rails 211. FIG. In one embodiment, receiver 325 is in the lowest impedance path to couple modulated signal 228 to the electrodes of display / sense panel 234. In one embodiment, the transmitter 415 also drives the modulation signal 228 on the reference voltage rail 211 using a connection of the power management controller to the reference voltage rail 211.

  [0076] As shown, a capacitor 405 is disposed in the electrical path coupling the receiver 325 to the voltage rail 211A, although the capacitor 405 is optional. The receiver 325 measures the charge (or voltage) accumulated in the capacitor 405 when the transmitter 415 modulates the reference voltage rail 211 to determine when the input object approaches the display / sense panel 234. .

  [0077] FIG. 5 is a circuit diagram of the reference voltage modulator 226 shown in FIG. 3 according to embodiments described herein. The modulator 226 includes an integrator 500 that outputs a modulation signal 228. Furthermore, since the integrator 500 acts as a receiver, the modulator also obtains a result signal from the display and sensor electrodes at the output of the integrator 500. One input of the amplifier of integrator 500 is coupled to signal generator 515, which outputs a modulated signal that is used by integrator 500 to drive modulated signal 228 through feedback from the sensor output. To do. For example, the integration function is performed by the capacitor 525 of the low-pass filter, and the offset drift is compensated by the reset switch or the optional resistor 520, for example.

  [0078] Generally describing the function of the reference voltage modulator 226, the integrator 500 determines the charge that the amplifier must provide through the capacitor 525 to modulate the display and sensor electrodes of the display panel by modulating the reference voltage rail. Measure the quantity (using the result signal). Although not shown, receiver 325 is coupled to a filter and sampling circuit, eg, an ADC, for processing the resulting signal. Furthermore, FIG. 5 shows only one example of a suitable structure for the reference voltage modulator 226 and the receiver. Generally speaking, the modulator 226 is any type of transmitter circuit that drives the modulation signal 228 and any type of analog circuit for receiving a measurement of the capacitance or capacitance change of the circuit. Alternatively, as shown in FIG. 4, the receiver 325 is separate from the reference voltage modulator. For example, the reference voltage modulator includes only the modulator that drives the modulation signal 228, while the receiver is located anywhere in the processing system (eg, a separate integrated circuit of the power management controller, etc.).

[0079] FIG. 6 is a flowchart illustrating a method 600 for waking up an input device from a low power state using a modulated reference voltage rail, according to one embodiment described herein. In block 605, the timing controller electrically isolates the reference voltage rail from the power supply by selectively disconnecting the rail or using an indirect coupling method such as inductive coupling. For example, the power source is a battery that provides DC voltage outputs (eg, V _DD and V _GND ) to energize various components of the input device. The timing controller electrically isolates the reference voltage rail from the battery because the function of certain components is negatively affected by modulating the output of the power supply. Alternatively, the timing controller allows the reference voltage rail to be electrically connected to the power source when updating the input device display or performing capacitive sensing that does not modulate the reference voltage rail. During these time periods, the power supply directly drives an unmodulated DC voltage on the voltage rail. In some embodiments, power is consistently applied even when the voltage rail is modulated relative to chassis ground, floated, or held at a relatively constant voltage (eg, the voltage rail is inductively coupled to the power source). Combined).

  [0080] At block 610, the input device configures the input device in a low power state. In one embodiment, the input device determines to enter a low power state after identifying a period of dark activity when the user fails to interact with the input device. For example, if the user does not use an input device function (eg, touching the sensing area, making a phone call, touching a button, etc.) within a predetermined time period, the input device will switch to a low power state. Change. In another example, the user instructs the input device to enter a low power state by making a predetermined gesture in the sensing area or activating a particular button.

  [0081] In a low power state, the input device disables one or more components (eg, power supply, PMIC, backlight, etc.) of the input device to conserve power. As shown in FIG. 2, the reference voltage modulator 226 obtains a result signal for performing capacitive sensing, so that the sensor module 222 and the corresponding capacitive sensing circuit in the display / sensing panel 234 (if any). ) Is deactivated. Similarly, the display module 224 and the display circuit 236 can be disabled when the low power state does not require an image to be displayed. Further, the input device can effectively disable the components of the display / sense panel 234 by disabling the power management controller 230 to stop supplying power to the panel 234. Further, the backlight 232 is turned off by deactivating the power management controller 230. In one embodiment, a low power state means that at least all energized components in sensor module 222, display module 224, power management controller 230, and display / sense panel 234 are deactivated. However, in other embodiments, some of these components remain energized in the low power state.

  [0082] At block 615, the reference voltage modulator modulates the reference voltage rail relative to the chassis ground of the input device. At block 620, while modulating the voltage rail, the receiver simultaneously obtains a result signal from the panel display and sensor electrodes. To do so, the receiver is coupled to the panel display and sensor electrodes at a common electrical node, eg, supply voltage. Using the resulting signal, the receiver (or other component of the input device) determines the capacitance or capacitance change corresponding to the display and sensor electrodes. By comparing this capacitance measurement with one or more thresholds, the input device can detect when the input object approaches the panel.

  [0083] The receiver is integrated into a reference voltage modulator that generates a signal to modulate the reference voltage rail, but can be received anywhere in the processing system where it can be coupled to a display and / or sensor electrode in the panel. A vessel may be placed. For example, the receiver is located in the timing controller at a different location than the reference voltage modulator, or in a completely separate integrated circuit. Further, the receiver may be located in the power management controller. In one embodiment, the receiver is coupled to one (or both) of the modulated reference voltage rails regardless of their position.

  [0084] At block 625, the input device determines whether the input object has approached the display / sense panel by evaluating the result signal obtained at block 620. If the input object does not approach the input device (eg, does not touch the panel or hover over the panel), the method 600 proceeds to 620 and the receiver again signals the result signal while the voltage rail is modulated. To get. For example, when in a low power state, the input device modulates the reference voltage rail at certain intervals and obtains a result signal until an input object is detected. The duty cycle of these low power cycles is low, eg, greater than 10 ms, but fast enough to track environmental changes, eg, faster than 100 seconds.

  [0085] 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, switching from a low power state to an active state activates at least one component that was inactive or de-energized in the low power state. For example, the input device operates the sensor module and capacitive sensing circuit of the panel to perform capacitive sensing and determine a specific position of the input object on the panel. Alternatively or additionally, the input device activates the display module and display circuit (and backlight) so that an image is displayed. In some low power modes, no modulation of the reference voltage is required and interference is detected or the presence of an active pen is detected. For example, the duty cycle when performing viewing or active pen detection is slow (eg, less than 100 ms).

  [0086] In one embodiment, when in an active state, some of the components of the input device are still disabled. For example, at block 630, the input device activates only those components necessary to perform capacitive sensing to determine the position of the input object on the panel. Display components (eg, backlights or display modules) are still disabled. For example, when in an active state, the input device uses the sensor module to ensure that the input object detected at block 625 is not a false positive before activating the display component. In another example, the reference voltage modulator detects when the input object approaches (eg, hovers) the display and then switches the input device to an active state at block 630. However, before activating the display component, the input device uses the sensor module to determine whether the user has made a default wake-up gesture using the input object. Thus, although not shown in method 600, the active state draws more power than the low power state, but for example draws more power than the fully active state where both display updating and capacitive sensing are performed. Low intermediate power state.

  [0087] FIG. 7 illustrates an example electrode configuration for performing capacitive sensing according to one embodiment described herein. FIG. 7 illustrates a portion of a sensor electrode pattern comprising sensor electrodes 710 configured to perform sensing in a sensing region associated with the sensor electrode pattern according to an embodiment. For clarity of illustration and description, FIG. 7 shows a simple rectangular pattern and does not show the various components. Further, as illustrated, the sensor electrode 710 includes a first plurality of sensor electrodes 720 and a second plurality of sensor electrodes 730.

  [0088] In one embodiment, sensor electrodes 710 are disposed on different sides of the same substrate. For example, each of the first and second plurality of sensor electrodes 720 and 730 is disposed on one of the substrate surfaces. In other embodiments, sensor electrodes 710 are disposed on different substrates. For example, each of the first and second plurality of sensor electrodes 720, 730 is disposed on the surface of a separate substrate that is bonded together. In another embodiment, the sensor electrodes 710 are all disposed on the same side or surface of a common substrate. In one example, the first plurality of sensor electrodes includes jumpers in a region where the first plurality of sensor electrodes intersects the second plurality of sensor electrodes, and the jumpers are insulated from the second plurality of sensor electrodes. The

  [0089] The first plurality of sensor electrodes 720 extends in a first direction, and the second plurality of sensor electrodes 730 extends in a second direction. The second direction may be the same as or different from the first direction. For example, the second direction may be parallel to the first direction, may be perpendicular, or may be a diagonal direction. Further, the sensor electrodes 710 may each be the same size or shape, or may be different sizes and shapes. In one embodiment, the first plurality of sensor electrodes may be larger than the second plurality of sensor electrodes (having a large surface area). In other embodiments, the first and second plurality of sensor electrodes may be similar in size and / or shape. Accordingly, the size and / or shape of one or more sensor electrodes 710 may be different from the size and / or shape of another one or more sensor electrodes 710. Still, each of the sensor electrodes 710 can be formed in a desired shape on each substrate.

  [0090] In other embodiments, one or more sensor electrodes 710 are disposed on the same side or surface of the common substrate and separated from each other in the sensing region. The sensor electrodes 720 are arranged in a matrix array, and each sensor electrode is referred to as a matrix sensor electrode. Each sensor electrode of sensor electrode 710 in the matrix array may be substantially similar in size and / or shape. In one embodiment, the one or more sensor electrodes of the matrix array of sensor electrodes 710 vary in size and / or shape. Each sensor electrode of the matrix array may correspond to a pixel in the capacitive region. Furthermore, two or more sensor electrodes of the matrix array may correspond to pixels of the capacitive image. In various embodiments, a separate capacitive root trace of a plurality of capacitive root traces is coupled to each sensor electrode of the matrix array. In various embodiments, sensor electrode 710 includes one or more grid electrodes disposed between at least two sensor electrodes of sensor electrode 710. The grid electrode and the at least one sensor electrode are disposed on a common side of the substrate, a different side of the common substrate, and / or a different substrate. In one or more embodiments, the grid electrode of the sensor electrode 710 surrounds the entire voltage electrode of the display device. The sensor electrodes 710 are electrically isolated at the substrate, but the electrodes are coupled together outside the sensing area, eg, at the connection area. In one embodiment, a floating electrode is disposed between the grid electrode and the sensor electrode. In one particular embodiment, the floating electrode, the grid electrode and the sensor electrode constitute the entire common electrode of the display device.

  [0091] The processing system 110 shown in FIG. 1 modulates one or more sensor electrodes of the sensor electrode 710 with a modulation signal (ie, an absolute capacitive sensing signal) to determine a change in the absolute capacitance of the sensor electrode 710. Configured to drive. In certain embodiments, the processing system 110 is configured to drive a transmit signal at the first electrode of the sensor electrode 710 and receive a result signal at the second electrode of the sensor electrode 710. The transmitted signal (s) and the absolute capacitive sensing signal (s) are similar in at least one of shape, amplitude, frequency and phase. The processing system 110 is configured to operate the grid electrode as a shield and / or protective electrode by driving the grid electrode with a shield signal. Further, the processing system 110 is configured such that the grid electrode is driven with a transmitted signal to determine capacitive coupling between the grid electrode and one or more sensor electrodes, or absolute capacitive sensing. Driven with the signal, the absolute capacitance of the grid electrode is determined.

  [0092] As used herein, a shield signal refers to a signal having one of a constant voltage or a changing voltage signal (protection signal). The protection signal is substantially similar in amplitude and / or phase to the signal that modulates the sensor electrode. Further, in various embodiments, the protection signal has an amplitude that is greater or less than the signal that modulates the sensor electrode. In some embodiments, the protection signal has a different phase than the signal that modulates the sensor electrode. Electrically floating an electrode can be interpreted as a form of protection when the second electrode receives a desired protective waveform via capacitive coupling from a driven sensor electrode in the vicinity of the input device 100 due to floating. it can.

  [0093] As described above, in any of the sensor electrode configurations, the sensor electrode 710 is formed on a substrate external or internal to the display device. For example, the sensor electrode 710 is disposed on the outer surface of the lens in the input device 100. In another embodiment, the sensor electrode 710 is 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 electrodes are positioned such that they fall 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. Arranged between. In yet another embodiment, all sensor electrodes 710 are disposed between the TFT substrate and the color filter glass of the display device, and the sensor electrodes are disposed on the same substrate or on different substrates as described above. Placed in.

[0094] In any of the sensor electrode configurations described above, the sensor electrode 710 is for transcapacitance sensing by dividing the sensor electrode 710 into a transmit electrode and a receive electrode, or for absolute capacitive sensing, or Operated by the input device 100 for both mixing. In addition, one or more of sensor electrodes 710 or display electrodes (eg, source, gate, or reference (V _com ) electrodes) are used to perform the shielding action.

  [0095] The area of local capacitive coupling between the first plurality of sensor electrodes 720 and the second plurality of sensor electrodes 730 forms a capacitive pixel. The capacitive coupling between the first plurality of sensor electrodes 720 and the second plurality of sensor electrodes 730 is an input in a sensing region associated with the first plurality of sensor electrodes 720 and the second plurality of sensor electrodes 730. It changes with the proximity and movement of the object. Furthermore, the area of local capacitance between the first plurality of sensor electrodes 720 and the input object and / or between the second plurality of sensor electrodes 730 and the input object also forms a capacitive pixel. Accordingly, the absolute capacitance of the first plurality of sensor electrodes 720 and / or the second plurality of sensor electrodes 730 is in a sensing region associated with the first plurality of sensor electrodes 720 and the second plurality of sensor electrodes 730. It changes with the proximity and movement of the input object.

  [0096] In some embodiments, sensor patterns are "scanned" to determine their capacitive coupling. That is, in one embodiment, the first plurality of sensor electrodes 720 are driven to transmit a transmission signal by, for example, the sensor module 222 of FIG. The transmitter is operated such that one transmitter electrode transmits at a time or multiple transmitter electrodes transmit simultaneously. When a plurality of transmission electrodes perform transmission simultaneously, the plurality of transmission electrodes may transmit the same transmission signal to effectively form a large transmission electrode, or the plurality of transmission electrodes may Different transmission signals may be transmitted. For example, the plurality of transmit electrodes may transmit different transmit signals according to one or more code schemes that can have their combined effect on the resulting signal of the second plurality of sensor electrodes.

  [0097] The receiving sensor electrodes are operated alone or in plurality to obtain a result signal. The result signal is used to determine a measure of capacitive coupling in the capacitive pixel. The receive electrode may also be scaled (eg, by a multiplexer) to a small number of capacitive measurement inputs to receive the signal.

  [0098] In other embodiments, scanning the sensor pattern includes one or more sensor electrodes of the first and / or second plurality of sensor electrodes while receiving a result signal at the one or more sensor electrodes. Driving with an absolute sensing signal. The sensor electrodes are driven and received so that one second electrode is driven and received at a time or multiple sensor electrodes are driven and received simultaneously. The result signal is used to determine a measure of capacitive coupling at the capacitive pixel or along each sensor electrode.

  [0099] A set of measurements from capacitive pixels forms a "capacitive frame". The capacitive frame includes a “capacitive image” representing capacitive coupling at the pixel and / or a “capacitive profile” representing capacitive coupling or along each sensor electrode. Multiple capacitive frames are acquired over multiple time periods and the difference between them is used to derive information about the input in the sensing region. For example, successive capacitive frames acquired over successive time periods are used to track the movement of one or more input objects entering, exiting and within the sensing area.

  [00100] The background capacitance of the sensor device is a capacitive frame associated with the absence of input objects in the sensing area. Background capacitance varies with the environment and operating conditions and is estimated in various ways. For example, in one embodiment, a “baseline frame” is taken when it is determined that there are no input objects in the sensing area, and this baseline frame is used as an estimate of those background capacitances.

  [00101] The capacitive frame can be adjusted to the background capacitance of the sensor device for more efficient processing. In one embodiment, this is done by “baselining” the capacitive coupling measurement in the capacitive pixel to generate a “baseline capacitive frame”. That is, in one embodiment, the measurements that make up the capacitance frame are compared to the appropriate “baseline value” of the “baseline frame” and the change from that baseline image is determined. These baseline images are also used in the low power mode described above for profile sensing or actively modulated active pens.

Interference and active pen detection
[00102] FIG. 8 illustrates an input device 800 that detects noise (or interference) signals or communication signals from an active input object according to one embodiment described herein. The input device 800 has a structure similar to that of the input device 300 of FIG. 3. In fact, each input device can perform the reference voltage modulation described in FIG. 3, and interference and active input object detection. However, in other embodiments, the input device is configured to perform only one of these functions. In one embodiment, active objects are actively modulated with a known or configurable frequency, duty cycle, time encoding, etc. relative to chassis ground.

  [00103] The timing controller 805 of the input device 800 includes a central receiver 810 coupled to the low reference voltage rail 211B. Similar to the receiver 325 of FIG. 3, the central receiver 810 is coupled to the display and sense electrodes of the display / sense panel 234 via the power management controller 230 power supply. In one embodiment, the central receiver 810 is directly connected to several components in the display / sense panel 234 because the voltage rail 211 is also directly connected to the panel 234, but is connected to the panel 234 via the controller 230 power supply. Indirectly coupled to other components. In any case, all the electrodes (and possibly other components of panel 234) are coupled to a common electrical node with central receiver 819, so that panel 234 functions as a single capacitive pixel.

  [00104] However, the central receiver 810 need not be coupled to all display and sensor electrodes in the panel 234, but rather can be coupled to only display electrodes or only sensor electrodes. However, by limiting the number of electrodes coupled to the central receiver 810 (eg, a single source driver), the size of the sensing area in the panel 234 (or capacitive pixel sensitivity) is reduced across the panel. A portion of the panel is measured even when the electrodes are scanned.

[00105] Unlike the embodiment shown in FIG. 3, to detect interference or communication signals from an active input object (eg, a stylus or pen with a wireless transmitter), the input device 800 uses a reference voltage rail 211. Do not modulate. Rather, the rail 211 holds an unmodulated DC voltage with respect to chassis ground. However, as in FIG. 3, the timing controller 805 electrically disconnects the voltage rail 211 from the power supply voltages V _DD and V _GND before detecting an interference or communication signal. Using signals 330A, 330B, timing controller 805 opens switches 210, 212 and disconnects voltage rail 211 from the power supply voltage. Alternatively, the reference voltage rail 211 is inductively coupled to the power supply voltage, in which case the rail 211 is always isolated from these voltages.

  [00106] When a noise source or active input object approaches an electrode on the panel 234, an interference signal generated by the noise source or a digital communication signal generated by the input object is displayed in the display and sensor in the panel 234. A result signal is generated at the electrode, which is then acquired by the central receiver 810. By processing the result signal, the input device 800 identifies the interference signal and compensates for it. Some non-limiting examples of actions that the input device 800 takes to compensate for interfering signals include switching to different sensing frequencies, limiting the number of reported input objects, and some such as proximity detection or globe detection Stop using the feature, increase the number of frames that are averaged before detecting the touch position, ignore the new input object that is detected when the interference occurs, and if the sensor module leaves the sensing area Including preventing reporting or changing the capacitive frame rate.

  [00107] If the result signal is caused by an active input object, the input device 800 decodes the digital signal and performs the corresponding action. When the active input object transmits a communication signal using a wireless transmitter, the display and sensor electrodes on panel 234 serve as an antenna for receiving the signal. Thus, neither the noise source nor the active input object need to touch panel 234 to generate a result signal on the electrode of panel 234, for example, the input object may hover on panel 234.

  [00108] In addition, the display / sense panel 234 includes a plurality of local receivers 815 that are each coupled to each sensor electrode of the panel 234. When performing capacitive sensing, the local receiver 815 measures the resulting signal from each sensor electrode, which can be used to identify a specific location within the panel 234 where the input object touches or hoveres. . In one embodiment, the local receiver 815 performs a similar function as the receiver 810, i.e., both receivers 810, 815 measure capacitance. In one embodiment, rather than using a central receiver 810 to detect interfering or communication signals from active input objects, the input device may receive all of the signals received by the local receiver 815 on the panel 234. The result signal can be synthesized. However, the detection of interference and communication signals requires more power, or circuits that are more complex or more expensive than those required to perform capacitive sensing using the receiver 810. And Thus, when using local receiver 815 to detect interference or communication signals, it becomes more expensive than local receiver 815 used to perform only capacitive sensing using a modulated signal. . Thus, rather than having expensive receivers 815, the input device 800 need only use one central receiver 810 that can be used to detect interference and communication signals. The central receiver 810 has a wide dynamic range, fast ADC, and / or has a greater noise margin than the local receiver 815, so that the local receiver 815 is less expensive to manufacture than the central receiver 810. . Thus, in one embodiment, rather than having dozens, hundreds or expensive local receivers 815 that can identify interference and communication signals from active input objects, the input device 800 is a single receiver, i.e. Only the central receiver 810 is included. Since the local receiver 815 is not used to detect interference or communication signals, it is cheaper than it would be.

[00109] In one embodiment, the interference or communication signal is measured while the display is updated. That is, the timing controller includes a display module that actively updates pixels in the display / sense panel 234 while the central receiver 810 acquires signals as described above. Even if the power management controller 230 and the panel 234 are selectively disconnected (or separated) from the power supply voltages V _DD and V _GND, the charge stored in the bypass capacitor 214 is used to energize the voltage rail 211 and update the display. It can be performed. When the charge across capacitor 214 falls to the threshold, timing controller 805 reconnects voltage rail 211 and capacitor to power supply voltages V _DD and V _GND or otherwise couples the power supply voltage to rail 211 (eg, , Inductively coupled). Furthermore, the central receiver 810 stops measuring interference or communication signals when the voltage rail 211 is ohmically coupled to the power supply voltages V _DD and V _GND . However, capacitor 214 (e.g., 15 to 150 microfarads) may cause power management controller 230 for a period of time sufficient for central receiver 810 to identify interference signals generated by noise or communication signals provided by an active pen or stylus. And charge sufficient to energize the panel 234 is accumulated.

[00110] FIG. 9 is a circuit diagram of a central receiver 810 that obtains a result signal to identify noise or communication signals according to one embodiment described herein. The central receiver 810, like the integrator 500, includes an integrator 900 for obtaining a result signal from the display and sensor electrodes. Integrator 900 is implemented as a low pass filter with feedback capacitor 915 and optional resistor 920 when the feedback signal is measured, and controls the reference voltage on one rail 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 the chassis ground. Thus, the resulting signal caused by the interference signal generated by the noise source or the communication signal generated by the input object flows through the central receiver 810 and thus by the central receiver 810 rather than through another component of the input device. Measured. In other words, by selectively disconnecting or disconnecting the voltage rail from the power supply, the central receiver 810 becomes the lowest impedance path between the noise source and the active input object and the chassis ground, and thus the noise source. And the resulting signal generated by the active input object flows primarily to the central receiver 810 and the integrator 900, where the signal can be measured.

  [00111] However, integrator 900 is just one type of circuit suitable for performing the functions of central receiver 810. Generally speaking, the central receiver 810 is an analog circuit that measures capacitance. For example, the central receiver 810 includes circuitry that measures stored charge or voltage across the capacitor 925, or includes circuitry that measures capacitance using current flowing through the central receiver 810.

  [00112] FIG. 10 is a flowchart of a method 1000 for identifying noise or communication signals using capacitive sensing in accordance with one embodiment described herein. In block 1005, the input device isolates the reference voltage rail from the power source. For example, the switch selectively disconnects the reference voltage rail from the power source or the rail is permanently isolated from the power source by inductive coupling. In one embodiment, a capacitor (eg, as shown in FIG. 8) between rails to provide temporary power to components of the input device that are energized by a reference voltage rail that is disconnected when a capacitive sensing signal is received. A bypass capacitor 214) is connected. For example, display updates and capacitive sensing are performed while the voltage rail is disconnected from the power source.

  [00113] At block 1010, the central receiver is coupled to chassis ground (through a power source) and is also coupled to one or more display and / or sensor electrodes of the display / sensing panel. In addition, the central receiver provides a low impedance path between the electrode and ground. Thus, when a noise source is capacitively coupled to the panel electrodes or a communication signal from an active input device is received at the electrodes, a current loop is formed that flows through the central receiver.

  [00114] At block 1015, the central receiver simultaneously obtains result signals from the display and sensor electrodes. For example, the display electrode, sensor electrode, and central receiver are coupled to a common electrical node so that the resulting signal combination generated at the display electrode and sensor electrode flows through the receiver to the chassis ground.

  [00115] In one embodiment, the central receiver obtains a result signal when the display and sensor module is inoperative when in the low power state described in FIG. During the first time period, the input device obtains a result signal while the reference voltage rail is not modulated to identify an interference signal or a communication signal. During the second time period, the input device obtains a result signal while the reference voltage rail is modulated as described in FIG. Furthermore, if an interference signal is detected during the first time period, the input device modulates the voltage rail during the second time period to avoid harmful interference from the noise source. The modulation signal used for the above is changed. However, as described above, the method 1000 can be performed on its own or in parallel with the display update when the input device is in an active or high power state.

  [00116] In block 1020, the input device identifies at least one of an interference signal and a communication signal from an active input device based on the acquired result signal. When the interference signal is identified, the input device compensates the signal, for example, by switching to a modulation signal outside the range of the interference signal when performing capacitive sensing. If a communication signal is received, the input device processes the signal to determine information about the active input object. For example, the communication signal may be the current tilt of the input object relative to the display / sensing panel, the particular color or marking to be displayed where the input object touches the panel, or the input object or other that attempts to pair with the input device Identify the ID of the object (eg, Bluetooth connection). In another embodiment, the communication signal indicates to the input device that a button on the input object has been pressed by the user, which may be a specific function of the input device, such as switching to a low power state, Wake-up from the screen, opening a specific application, changing the appearance of markings displayed using an input object, and the like.

  [00117] In one embodiment, when a communication signal is received, the input device increases the number of detection frames used to detect the input object relative to the number of capacitive frames. Alternatively or in addition, the input device performs a coarse search (sensing using a group of sensor electrodes) and then detects the position of the input object during the coarse search and then searches for a granular search ( Detect each sensor electrode individually using a local receiver) to search for the position of the input object in the sensing area.

Reduction of the effect of low grounding mass
[00118] FIG. 11 illustrates various capacitances between the input device and the environment according to one embodiment described herein. As shown, system 1100 includes an input device 1105, an input object 1110, and a ground ground 1115, which are capacitively coupled. The input device 1105 includes a sensing area 1120 in the display / sensing panel to perform capacitive sensing. In one embodiment, by measuring the change in capacitance (C _T ) between the sensing area 1120 and the input object 1110, the input device 1105 determines whether the input object 1110 contacts or hoveres the sensing area 1120. decide. In some embodiments, the input device 1105 determines a specific location within the sensing area with which the input object 1110 interacts.

[00119] However, when performing capacitive sensing, the result signals measured by the input device 1105, in addition to C _T, may be affected by other capacitances in the system 1100. For example, the input object 1110 is capacitively coupled to the chassis of the input device 1105, which _is represented by _{C BC.} Further, both the input object 1110 and the chassis of the input device 1105 are capacitively coupled to a ground ground 1115, typically represented by C _IG and C _BG , respectively. Capacitances C _BC , C _BG and C _IG are referred to herein as ground state 1125. Typically, the input device 1105 cannot control the capacitance of the ground state 1125 that changes as the environment of the device 1105 changes. For example, the capacitance C _BC between the input object 1110 and the chassis varies based on whether the user holds the input device 1105 or the device 1105 is placed on a table. Furthermore, the capacitance C _IG between the input object 1110 and the earth ground 1115 changes when the user is standing on the ground or in the aircraft. Input device 1105 does not have a mechanism for measuring the position of the input device 1105 and input object 1110 in the environment, thus, affects the ability of the input device 1105 for the capacitance of the ground state 1125 to measure the _{C T} It cannot be determined accurately.

[00120] The capacitance C _T between the sensing area 1120 and the input device 1105, typically, because the minimum capacitance shown in FIG. 11, affects the amount of signal received by the input object 1105. This is because it is a limited impedance. However, the capacitance of the ground state 1125, because it decreases when the position of the input device 1105 or the input object 1110 in the environment changes, the capacitances may reduce the ability of the input device 1105 for accurately monitoring the C _T . For example, the same value combined capacitance is a C _T of C _T in series with the ground state 1125 (e.g., 10 pF 1), then a signal received at the input device can contribute to C _T is halved. For example, if the input device 1105 is placed on the user's knee, the capacitance C _{BG will be} approximately 50 pF, and therefore the influence on the signal measured by the input device 1105 will be small. However, when the input device 1105 is placed on the table in contact with the earth ground point 1115, a capacitance _{C BG} approximately 5 pF. Capacitances C _T and C _BG are now approximately the same, so the effect on the resulting signal obtained by input device 1105 that can contribute to C _T (ie, the capacitance that input device 1105 attempts to monitor) is approximately half. become. The configuration in which the capacitance of the ground state 1125 has a significant effect on the result signal measured by the input device 1105 is referred to herein as the low ground mass (LGM) state.

  [00121] When an LGM condition exists, the input device 1105 compares the resulting signal with the threshold used to detect a touch or hover event, assuming that the capacitance of the ground state 1125 is large, In some cases, the input device 1105 may fail to detect low capacitive changes in touch / hover events. In order to accurately detect touch / hover events during the LGM state, the input device 1105 can adjust the threshold low independently of the LGM or based on a host control mode (eg, the battery is charging) As described above, when the configurations of the input device 1105, the input object 1110, and the ground contact point 115 are detected, the LGM state becomes difficult or impossible. Rather, in the embodiment described herein, as described above, the resulting signal representing the total capacitance of the environment (including changes in ground state 1125) is measured at the central receiver by modulating the reference voltage rail. This total capacitance is correlated to measurements made by local receivers connected to individual sensor electrodes in the sensing area 1120. In one embodiment, the result signal obtained by the local receiver is normalized using the result signal obtained by the central receiver, and in doing so, the ground state 1125 relative to the local capacitance measurement. The effect of capacitance can be canceled (or reduced). In another embodiment, the threshold is adjusted to account for the estimated LGM based on the combination of the central receiver measurement and the local receiver measurement.

[00122] FIG. 12 illustrates an input device 1200 that modulates a reference voltage rail for capacitive sensing in accordance with one embodiment described herein. Similar to the input device shown in FIGS. 3 and 4, the input device 1200 modulates the reference voltage rail 211 for capacitive sensing using the reference voltage modulator 226. In one embodiment, timing controller 220 opens switches 210 and 212 so that reference voltage rail 211 is disconnected from power supply voltages V _DD and V _GND . As described above, disconnecting the power supply voltage prevents the modulation signal 228 from adversely affecting other components of the input device 1200 (not shown) that rely on V _DD and V _GND for power. .

[00123] The reference voltage modulator 226 comprises a central receiver 1205 that obtains a result signal generated by modulating the reference voltage rail 211. That is, while the modulation signal 228 is active, the central receiver 1205 measures the display on the panel 234 and / or the resulting signal from the sensor electrodes 240,242. In general, since the central receiver 1205 is coupled to the reference voltage rail 211, the receiver 1205 receives the result signal from a component of the panel 234 that is electrically connected (directly or indirectly) to the voltage rail 211. get. Referring to FIG. 11, in one embodiment, the resulting signal measured by the central receiver 1205 is affected by the capacitance C _T and the capacitance of the ground state 1125, ie, C _BC , C _IG and C _BG . Further, although the central receiver 1205 is shown coupled to the reference voltage rail 211B, in other embodiments, the receiver 1205 is coupled to the upper voltage rail 211A or other power source 335. Further, the central receiver 1205 need not be located on the controller 220 but can be located on the same integrated circuit as the power management controller 230 or on a separate integrated circuit.

  [00124] The input device 1200 also includes a local receiver 1210 disposed on the display / sense panel 234. In one embodiment, local receivers 1210 are each coupled to only one of the sensor electrodes to measure a local capacitance value corresponding to panel 234. That is, unlike the result signal obtained by the central receiver 1205 that is affected by the total capacitance of the display / sense panel 234, the result signal measured by the local receiver 1210 is affected by the local capacitance for a sub-portion of the panel 234. Is done. The shape and size of the sub-portion of panel 234 depends directly on the shape and size of sensor electrode 242 coupled to local receiver 1210. In one embodiment, local receiver 1210 is coupled to a plurality of sensor electrodes 242. Nevertheless, the local receiver 1210 measures the capacitance value for only a portion of the sensing area defined by the panel 234 and does not measure the total capacitance value for the panel 234 like the central receiver 1205.

  [00125] The input device 1200 measures the result signal at the central receiver 1205 at a different (non-overlapping) time period than the result signal measured at the local receiver 1210, but in one embodiment, the central and local reception Units 1205, 1210 measure the resulting signal in parallel (eg, measure at the same local receiver 1205 and central receiver 1210 simultaneously). In other words, both the central receiver 1205 and the local receiver 1210 can obtain the result signal when modulating the reference voltage rail 211 using the modulated signal 228. The result signal measured by the central receiver 1205 includes the result signal generated by all sensor electrodes 242 (and other components in the panel 234, eg, display electrodes 240), but is acquired by each local receiver 1210. The resulting signal is generated at only one or a subset of the sensor electrodes 242 and / or their thresholds. Also assume that user input and LGM state change slowly for these measurements. In this way, even in the measurement performed at the time of superimposition, the LGM state is synthesized so as to be estimated.

  [00126] Although the resulting signals measured by the central and local receivers 1205, 1210 are different, the measured values are equally affected by the capacitance of the ground state 1125 shown in FIG. That is, when measuring total capacitance and local capacitance, assuming that there is no change in the configuration of the input device 1105 with respect to the input object 1110 and the ground ground point 1115, the ground state 1125 for those measurements is It is essentially the same. Based on this relationship, the input device 1200 of FIG. 12 uses the total capacitance represented by the result signal received at the central receiver 1205 to normalize the result signal received at the local receiver 1210 to produce a local capacitance. The effect of the grounding state on the measured value can be reduced or eliminated.

[00127] FIG. 13 is a flowchart of a method 1300 for mitigating the effects of LGM states according to one embodiment described herein. In block 1305, the timing controller electrically connects the reference voltage rail from the DC power supply (ie, power supply voltages V _DD and V _GND ) by performing selective disconnection or using an indirect coupling technique such as inductive coupling. Separate. Referring to FIG. 12, the timing controller 220 uses the gate voltage to deactivate the switches 210, 212, thereby disconnecting the reference voltage rail 211 from the DC power source.

[00128] 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 chassis ground (eg, V _GND ). Thus, components that are connected to the modulated reference voltage rail are modulated with respect to the components of the input device that are not connected to the reference voltage rail. However, relative to the component connected to the reference voltage rail, the other components of the input device and the input object appear to be modulated.

  [00129] At block 1315, the central receiver obtains a result signal from the plurality of sensor electrodes. Since the sensor electrode establishes the sensing area of the display / sensing panel, by obtaining the result signal from the sensor electrode, the central receiver derives a general capacitive measurement of the panel from the result signal at block 1320. To do. In one embodiment, a typical capacitive measurement is the input device current caused by the resulting signal. Alternatively, a typical capacitive measurement may be a digital signal derived from the result signal using an ADC at the central receiver. In one embodiment, a typical capacitive measurement is caused by a result signal generated at all sensor electrodes in a display / sense panel and represents the total capacitance of the panel. In addition, the central receiver obtains result signals from the panel display electrodes and other circuitry and derives general capacitive measurements. FIG. 14 shows an exemplary system in which general capacitive measurements can be obtained by a central receiver.

  [00130] FIG. 14 illustrates various capacitances between the input device 1105 and the environment 1405 according to one embodiment described herein. In one embodiment, environment 1405 includes a surrounding area that approaches input device 1105. For example, the environment 1405 is an object that contacts the input device 1105, for example, a table on which the device 1105 is placed, or a user's hand holding the device 1105, and an object that is capacitively coupled to the input device 1105 but does not contact the device 1105. And an input object 1110 such as a finger or a stylus. In one embodiment, environment 1405 includes a ground ground point.

[00131] Different components of the input device 1105 are capacitively coupled to objects in the environment 1405, as shown in FIG. For example, the environment is capacitively coupled to the backplate chassis 1410 (eg, C ₁ ) and capacitively coupled to the display / sense panel 234 (C ₂ ). These capacitance values vary based on the location of the input device 1105 in the environment and environmental conditions (eg, humidity). For example, the values of C ₁ and C ₂ change when the input device 1105 is placed on the table vs. when it is held by the user. Capacitances C ₁ and C ₂ at least partially define the ground state of input device 1105. As described above, these capacitances, if they have the same value and the capacitance C _T between the input object 1110 and the current conveyor 1420, LGM state may occur.

[00132] The capacitance _{C 3} between the environment 1405 and the input object 1110 also affects the ground state of the input device 1105. The capacitance C ₃ is changed based on the position of the input object with respect to earth ground. For example, the value of C ₃ is the user (holding the input object 1110) is, instead of standing directly on the ground, is smaller when standing on the surface of the insulation. Similar to the capacitances C ₁ and C ₂ , the relative position of the input object 1110 and the object in the environment 1405 changes the capacitance C ₃ and creates an LGM condition, and the ability of the input device 1105 to measure C. Negative impact.

[00133] FIG. 14 also includes the capacitance C _HC between the backplate chassis 1410 (which is coupled to the chassis ground) and the input object that is part of the ground state of 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 changes based on whether the input device 1105 is placed on the user's knee or a table. Further, FIG 14 also includes coupling capacitance _{C P} between the display / sensing panel 234 and the input object 1110. 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 include display electrodes, other sensor electrodes, source drivers, gate line selection logic, etc. Coupled to other components in panel 234. In one embodiment, the capacitance C _P represents the total capacitance between the various components of the input object 1110 and the panel 234.

[00134] The central receiver 1205 is shown in this embodiment as an integrator that obtains a result signal from the display and / or sensor electrodes (and other circuitry) of the display / sensing panel 234. The acquired signal is affected by the various capacitances of FIG. 14, and thus, by processing the acquired signal when modulating the reference voltage rail, the central receiver can be configured as described in block 1320 of FIG. Capacitive sensing measurements can be derived. Although not shown, the central receiver 1205 includes a demodulator, filter, buffer, and / or ADC to process the acquired signal to derive general capacitive sensing measurements. Note that current conveyor 1420 and central receiver integrator 1205 perform a similar process as integrator 500 and integrator 900 described above. Further, as the integrator 500,900 has coalesced the reset switch for individual timing sensing, the integrator 1205 also is shown with a reset switch for integrating capacitance C _FB, for sensing successive time A low pass filter resistor such as resistor 520 may be combined. Further, the current conveyor 1420 may be used to perform a level shift of the capacitive sensing current to the voltage reference of the integrator 1205 and extend the effective dynamic range of the integrator 1205. Similar current conveyors may be included in integrators 500, 900 to perform the same function. Alternatively, if the dynamic range of the integrator 1205 is sufficient, the current conveyor 1420 is not necessary. Current from the display / sense panel 234 and the input object (eg, through a separate local receiver power supply) is routed directly to the integrator 1205 while the reference V _ref is modulated.

[00135] The output voltage (V _OUT ) of the integrator 1205 when obtaining the result signal is expressed as:

[00136] Capacitance C _B represents the background capacitance, where C _T = C _F + C _B. The current flowing from the display / sense panel 234 to the backplate chassis 1410 through the modulation power supply (V _MOD ) is expressed as follows:

[00137] Returning to FIG. 13, at block 1325, the input device determines a local capacitive sensing measurement from each sensor electrode. That is, instead of acquiring the result signal from multiple electrodes (e.g., a group of sensor electrodes, or both display and sensor electrodes) as in the central receiver, the input device uses each local receiver, A result signal is acquired from one sensor electrode. By processing the result signal, each local receiver can determine a local capacitive sensing measurement that represents a local capacitance value for a portion of the sensing area that includes the sensor electrode to which the local receiver is coupled. Thus, unlike the typical capacitive sensing measurement derived by the central receiver, the local capacitive sensing measurement represents the capacitance for a sub-portion of the sensing signal in the display / sensing panel. However, despite this difference between general capacitance measurements and local capacitance measurements, both measurements are equally affected by the ground state of the input device. That is, referring to FIG. 14, the capacitance _{C 1, C 2, C 3} , C HC and _{C P} exerts the same effect on the local capacitance measurements and general capacitance measurement. Therefore, when the value of the capacitance _{C 1, C 2, C 3} , C HC and _{C P} is changed, the local capacitance measurements and general capacitance measurement is correspondingly changed.

  [00138] In one embodiment, the local receiver obtains the result signal in parallel with the central receiver obtaining the result signal. In other words, both the local and central receivers measure the resulting signal while the input device modulates the reference voltage rail. Further, the local and central receivers may process the result signal in parallel to derive local and general capacitive sensing measurements, but this is not required. One advantage of simultaneously obtaining the result signal at the local and common receivers is that the ground conditions are the same (eg, measured simultaneously). If the result signal is acquired at a different time, the position of the input device in the environment changes, thereby changing the grounding state. As mentioned above, when the ground signal is the same, when the result signal is obtained at both the general and local receivers, the input device can determine the ground state from the local capacitive measurement by correlating the signal. The action of can be eliminated. However, even if the local and central receivers do not acquire the result signal in parallel, the ground state between the time when the local receiver measures the result signal and the time when the central receiver measures the result signal is slow. The change made (relative to the speed at which the capacitive measurement is made) is small, so the input device can still correlate the signal to reduce or eliminate the effects of ground conditions.

[00139] Using as an example a circuit diagram of FIG. 14, the current is measured to detect a touch through C _T at a current conveyor 1420 is expressed as follows.

[00140] The current I _{1 in} Equation 2 between the display / sense panel 234 and the backplate chassis 1410 is highly correlated with the current I _{2 in} Equation 3. For example, each of these currents depends on capacitances C _HP and C ₁ . Capacitance C _HP and C ₁ cause LGM when the configuration of input device 1105 in environment 1405 changes.

[00141] Returning to FIG. 13, at block 1330, the input device uses the result signal obtained by the central receiver to mitigate the effect of grounding on the result signal obtained by the local receiver. In one embodiment, the result signal measured by the central receiver (or a general capacitive measurement derived therefrom) is the result signal obtained by the local receiver (or local capacitive derived therefrom). Used to normalize the measured value). For example, the current I ₂ (eg, local capacitive sensing measurement) in Equation 3 can be normalized by dividing by the current I ₁ (eg, general capacitive sensing measurement) in Equation 2.

[00142] The normalized current shown in FIG. 4 is less dependent on the capacitance forming the ground state relative to the dependence on the currents I ₁ and I ₂ , so that the normalized current is the capacitance C _HC and C _1. Is not strongly correlated. In other words, changes in the values of capacitances C _HC and C ₁ cause only a small change (or no change) relative to the normalized current when compared to changes in the denormalized currents I ₁ and I ₂ .

[00143] FIG. 15 is a chart 1500 illustrating the results of mitigating the effects of LGM states according to one embodiment described herein. More specifically, the upper plot 1505 shows the corrected local receiver signal normalized using the result signal obtained by the central receiver, while the lower plot 1510 shows the uncorrected signal. As shown, the upper plot 1505 is a change in capacitive coupling (ie, C _HC ) between the input object 1110 and the backplate chassis 1410 and the backplate chassis 1410 and environment 1405 than the lower plot 1510. Less susceptible to changes in capacitive coupling (ie, C ₁ ) between them. Accordingly, changes in the values of ground state capacitances C _HC and C ₁ have less effect on the normalized capacitive sensing signal in plot 1505 than in the unnormalized capacitive sensing signal in plot 1510.

[00144] Another cost to normalize local capacitive sensing measurements using common capacitive sensing measurements is that the normalized signal is independent of V _MOD . Thus, noise coupled to the voltage used to modulate the reference voltage rail is canceled out. Furthermore, normalizing local and general capacitive measurements also reduces noise introduced by objects that cause ground conditions. For example, referring to FIG. 14, the noise introduced into the coupling capacitance _{C 1, C 2, C 3} , C HC and _{C P} via the input device 1105, the result signal obtained by the local receiver and the central receiver Is canceled by correlating. Thus, the noise signal introduced by the grounded capacitance coupling the input device to the external object can be removed.

  [00145] An exemplary embodiment of the first group is described below.

In the first example, the input device is
A plurality of sensor electrodes;
A processing system;
The processing system comprises
A sensor module configured to operate a plurality of sensor electrodes for capacitive sensing;
A reference voltage modulator configured to modulate a reference voltage rail of a processing system, and a reception configured to simultaneously acquire a result signal from a sensor electrode to detect an input object while modulating the reference voltage rail vessel,
Is included.

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

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

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

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

  In a sixth example of the input device of Example 1, the input device further comprises a display and the sensor electrode is external to the display.

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

In an eleventh example of the input device of example 1, the processing system further comprises:
A display module configured to update pixels of the display screen, the display module being configured as a timing controller and disposed within the first integrated circuit;
A source driver configured to update a pixel based on a signal received from the display module, the source driver and the sensor module are disposed in the second integrated circuit, and at least a portion of the reference voltage modulator is Located outside the first and second integrated circuits.

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

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

  In a fourteenth example of the input device of Example 1, the processing system further comprises a display module configured to update a pixel of the display screen using a reference voltage rail, wherein the reference voltage is updated when the pixel is updated. The rail is held at an unmodulated DC voltage.

  In a fifteenth example of the input device of Example 14, the input device further comprises a power management controller configured to form a plurality of power rails using the reference voltage rail, the power management controller comprising: A low power state is entered when the voltage modulator modulates the reference voltage rail, and an active state when the display module updates the pixel.

  In a sixteenth example of the input device of Example 1, the input device further comprises a plurality of display electrodes, and the receiver includes the display electrodes and sensing to perform capacitive sensing while modulating the reference voltage rail. The result signal is configured to be acquired simultaneously from both electrodes.

  In a seventeenth example of the input device of Example 1, the input device further comprises a display panel including a display screen and a backlight, and the reference voltage modulator is connected to the reference voltage rail when the backlight and the display panel are turned off. Is configured to modulate.

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

In a nineteenth example of the input device of example 18, the input device further comprises:
Display source,
A display panel;
A high-speed data interface located on the same integrated circuit as the reference voltage modulator;
And the data interface is configured to communicate with the display source to receive display data and update the display screen, and the high speed data interface has the reference voltage rail electrically disconnected from the DC power source. A portion of an unmodulated voltage domain that includes a power rail that sometimes remains coupled to a DC power source.

In a twentieth example, the processing system
A sensor module configured to drive a plurality of sensor electrodes for capacitive sensing;
A reference voltage modulator configured to modulate a reference voltage rail of the processing system;
And prior to modulating the voltage rail, the processing system is configured to electrically disconnect the reference voltage rail from the at least one DC power source, and to detect an input object while modulating the voltage rail A receiver configured to obtain a result signal using a sensor electrode;
It has.

  In a twenty-first example, the processing system of the twentieth example further comprises a display module configured to update pixels of the display screen using the reference voltage rail, and when updating the pixel, the reference voltage rail Is held at an unmodulated DC voltage.

  In a twenty-second example, in the processing system of the twenty-first example, the display module is configured to couple to the plurality of display electrodes to update the pixel, and the receiver has a capacitance while modulating the reference voltage rail. It is configured to simultaneously acquire a result signal from both the display electrode and the sensing electrode to perform sexual sensing.

  In a twenty-third example, the processing system of the twentieth example further comprises a display module configured to update the pixels of the display screen, and the display module is integrated into the integrated circuit along at least a portion of the sensor module. Be placed.

  In the twenty-fourth example, the processing system of the twentieth example further comprises a display module configured to update the pixels of the display screen, the display module being 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 twenty-fifth example, the processing system of the twentieth example further comprises a display module configured to update the pixels of the display screen, the display module being disposed in the first integrated circuit, and At least a portion of the sensor module is disposed within the second integrated circuit, and at least a portion of the reference voltage modulator is disposed external to the first and second integrated circuits.

  In a twenty-sixth example, the processing system of the twentieth example further comprises a display module configured to update the pixels of the display screen, the display module being disposed in the integrated circuit and the reference voltage modulation At least a portion of the vessel is external to the integrated circuit.

In the twenty-seventh example, the processing system of the twentieth example further includes:
A display module configured to update pixels of the display screen, the display module being configured as a timing controller and disposed within the first integrated circuit;
A source driver configured to update a pixel based on a signal received from the display module, the source driver and the sensor module being disposed in the second integrated circuit, and at least a portion of the reference voltage modulator comprising: Arranged outside the first and second integrated circuits.

  In a twenty-eighth example, the processing system of the twentieth example is configured to electrically disconnect the reference voltage rail from at least one DC power supply before modulating the voltage rail.

In the twenty-ninth example, the input device is
A plurality of sensor electrodes each including at least one common electrode of the display device, the sensor electrodes being arranged in a matrix array on a common plane;
A processing system, the processing system comprising:
A sensor module configured to operate a plurality of sensor electrodes for capacitive sensing;
A reference voltage modulator configured to modulate the reference voltage rail of the processing system, and configured to obtain a result signal using the sensor electrode to detect an input object while modulating the voltage rail Receiver,
Is included.

  In a thirtieth example, with the input device of the twenty-ninth example, prior to modulating the voltage rail, the processing system is configured to electrically disconnect the reference voltage rail from the at least one DC power source, In addition, a display module configured to update a pixel of the display screen using a reference voltage rail, and when updating the pixel, the reference voltage rail is held at an unmodulated DC voltage.

In the thirty-first example, the method
Driving capacitive sensing signals on multiple sensor electrodes of the input device;
Electrically disconnecting the reference voltage rail from at least one DC power source;
After electrically disconnecting the reference voltage rail, modulate the reference voltage rail,
Using sensor electrodes to detect the input object while modulating the voltage rail to obtain a result signal,
Including that.

  [00146] A second group of exemplary embodiments is described below.

In the first example, the input device is
A plurality of display electrodes;
A plurality of sensor electrodes;
A processing system;
The processing system comprises
A reference voltage modulator configured to modulate the reference voltage rail during the first time period; and
The display is updated using the display electrode and the reference voltage rail of the processing system during a second time period that is non-overlapping with the first time period, and the reference voltage rail is unmodulated and constant during the first time period. Held in voltage,
Obtaining a result signal from a plurality of sensor electrodes during a first time period;
Configured as follows.

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

  In a third example, the input device of the first example further comprises a source driver coupled to the plurality of sensor electrodes, the source driver driving a capacitive sensing signal to the sensor electrode for capacitive sensing. And the capacitive sensing signal is derived from the modulated reference voltage rail.

  In a fourth example of the input device of Example 3, the source sensor electrode is protected from at least one interference signal when driven by a capacitive sensing signal derived from a modulated reference voltage rail.

In the fifth example, the input device of the third example further includes:
A gate electrode for updating the display;
A source electrode for updating the display;
When the capacitive sensing signal is driven with the sensor electrode, the gate electrode is floated and the source electrode is protected.

  In the sixth example, the input device of the first example further receives an unmodulated reference voltage rail when the display is updated, and supplies the reference voltage rail to the display circuit of the display panel including the display. A power management controller configured to convert the power supply voltage to

  In a seventh example of the sixth example input device, the power management controller is in a low power state when the reference voltage modulator modulates the reference voltage rail and is active when the display module updates the pixel. It becomes a state.

  In an eighth example of the fourth example input device, the receiver is configured to simultaneously obtain a result signal from both the display electrode and the sense electrode to perform capacitive sensing.

  In a ninth example, the input device of the first example further comprises a backlight, and the reference voltage modulator is configured to modulate the reference voltage rail while the backlight and display are turned off.

In the tenth example, the input device of the first example further includes:
Display source,
A display panel;
A high-speed data interface located on the same integrated circuit as the reference voltage modulator;
The data interface is configured to communicate with a display source and receive display data for display updates, and the high-speed data interface is unmodulated when the reference voltage rail is modulated by a reference voltage modulator Is the portion of the unmodulated voltage domain that includes the supply voltage rail that remains.

In an eleventh example, the processing system
A reference voltage modulator configured to modulate the reference voltage rail during the first time period;
A receiver configured to obtain a result signal for a plurality of sensor electrodes during a first time period;
A display module configured to update the display using a plurality of display electrodes and a reference voltage rail during a second time period that does not overlap with the first time period;
And the reference voltage rail is held at an unmodulated DC voltage during the second time period.

  In a twelfth example of the eleventh example processing system, the reference voltage rail is capacitively coupled.

  In a thirteenth example of the eleventh example processing system, the processing system further receives an unmodulated reference voltage rail when updating the display and transfers the reference voltage rail to the display circuit of the display panel including the display. A power management controller configured to convert to a power supply voltage for energization is provided.

  In a fourteenth example of the thirteenth example processing system, the power management controller is in a low power state when the reference voltage modulator modulates the reference voltage rail and is active when the display module updates the pixel. It becomes a state.

  In a fifteenth example of the eleventh example processing system, the receiver is configured to simultaneously acquire a result signal from both the display electrode and the sense electrode to perform capacitive sensing.

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

  In a seventeenth example, the processing system of the eleventh example further comprises a high speed data interface disposed on the same integrated circuit as the reference voltage modulator, the data interface communicating with a display source for display update. The high speed data interface is configured to receive display data for a portion of an unmodulated voltage domain that includes a power supply voltage rail that remains unmodulated when the reference voltage rail is modulated by a reference voltage modulator. is there.

In an eighteenth example, the method is:
Updating a pixel of the display of the input device using a reference voltage rail and a plurality of display electrodes during a first time period, the reference voltage rail being held at an unmodulated DC voltage during the first time period;
Modulating the reference voltage rail during a second time period that does not overlap with the first time period;
Obtaining result signals from multiple sensor electrodes based on modulation of a reference voltage rail;
Including that.

In the nineteenth example, the method of the eighteenth example is the method wherein the input device is in a low power state during the second time period and after detecting the input object based on the result signal,
Switch the input device from a low power state to an active state,
Stop modulation of the reference rail,
Including that.

  In the twentieth example, the method of the eighteenth example further includes electrically disconnecting the DC power source from the reference voltage rail prior to modulating the reference voltage rail.

  A twenty-first example of the eighteenth example method for obtaining a result signal includes receiving each result signal simultaneously from the display electrode and the sensor electrode, and each result signal is used to perform capacitive sensing. The

  [00147] A third group of exemplary embodiments is described below.

In the first example, the input device is
A plurality of sensor electrodes;
A processing system;
The processing system comprises
A reference voltage modulator configured to modulate a reference voltage used to power a plurality of power sources;
A central receiver configured to simultaneously acquire a first result signal from a plurality of sensor electrodes when a reference voltage is modulated; and a plurality of local receivers each coupled to at least one of the sensor electrodes;
And the local receiver is configured to obtain a second result signal from the sensor electrode, and the processing system uses the first result signal to cause a ground condition to affect the second result signal. Configured to mitigate effects.

  In the second example, the input device of the first example further comprises a controller configured to disconnect the reference voltage from the DC power source while the reference voltage is modulated.

  In a third example, the input device of the first example further comprises a display / sensing panel including a plurality of sensor electrodes, a plurality of local receivers and a plurality of display electrodes, each of the sensor electrodes being a local receiver. Only one of them.

  In the fourth example of the input device of the first example, obtaining the second result signal at the local receiver means obtaining the first result signal at the central receiver when the reference voltage is modulated. And done in parallel.

  In a fifth example of the first example input device, the central receiver is configured to obtain a third result signal from the plurality of display electrodes while the reference voltage is modulated, and the processing system comprises: The third result signal is used to mitigate the effect of grounding on the second result signal.

  In a sixth example of the first example input device, the ground state is: (i) a first capacitive coupling between an input object interacting with the input device and a ground ground; and (ii) the input device. And / or a second capacitive coupling between ground and ground.

  In a seventh example of the first example input device, the processing system further comprises a display module configured to update the pixels of the display screen, the display module and the local receiver comprising a common integrated circuit. Placed inside.

  In an eighth example of the first example input device, the processing system further comprises a display module configured to update the pixels of the display screen, the display module being disposed within the first integrated circuit. And at least a portion of the local receiver is disposed in the second integrated circuit.

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

In the tenth example, the processing system
A reference voltage modulator configured to modulate a reference voltage used to power a plurality of power sources;
A central receiver configured to simultaneously acquire a first result signal from a plurality of sensor electrodes when a reference voltage is modulated;
A plurality of local receivers configured to obtain a second result signal from the plurality of sensor electrodes;
And the processing system is configured to use the first result signal to mitigate the effect of the ground condition on the second result signal.

  In the eleventh example, the processing system of the tenth example is further configured to disconnect the reference voltage from the DC power source while the reference voltage is modulated.

  In a twelfth example of the tenth example processing system, the twelfth example further comprises a power management controller including a power source, the power source configured to supply power to the display.

  In the thirteenth example of the processing system of the tenth example, obtaining the second result signal at the local receiver is obtaining the first result signal at the central receiver when the reference voltage is modulated. And done in parallel.

  In a fourteenth example of the tenth example processing system, the central receiver is configured to obtain a third result signal from the plurality of display electrodes while the reference voltage is modulated, and the processing system comprises: The third result signal is used to mitigate the effect of grounding on the second result signal.

  In a fifteenth example of the tenth example processing system, the ground state is: (i) a first capacitive coupling between an input object that interacts with the chassis containing the processing system and a ground ground point; ii) at least one of a second capacitive coupling between the chassis and earth ground.

In a sixteenth example, the method is:
Modulate the reference voltage used to power multiple power sources,
While modulating the reference voltage, simultaneously acquiring a first result signal from a plurality of sensor electrodes at the central receiver;
Obtaining a second result signal from the sensor electrode at a plurality of local receivers;
Using the first result signal to mitigate the effect of grounding on the second result signal;
Including that.

  In the seventeenth example, the method of the sixteenth example further includes electrically isolating the reference voltage from the DC power source while the reference voltage is modulated.

  In an eighteenth example of the sixteenth example method, the first result signal is obtained at the central receiver in parallel with obtaining the second result signal at the plurality of local receivers.

In a nineteenth example of the sixteenth example method,
Simultaneously acquiring a third result signal from the plurality of display electrodes at the central receiver while modulating the reference voltage;
Using the third result signal to reduce the effect of grounding on the second result signal;
Including that.

  [00148] Accordingly, the embodiments and examples described herein are intended to best describe the embodiments based on the technology of the present invention and its particular application, and therefore, those skilled in the art will understand the technology of the present invention. Can be used. However, one of ordinary skill in the art will recognize that the above description and examples are for illustrative purposes only. The above description is not exhaustive and is not intended to limit the disclosure to the precise form shown.

  [00149] In view of the above, the scope of the present disclosure is determined by the claims.

DESCRIPTION OF SYMBOLS 100 ... Input device, 110 ... Processing system, 120 ... Sensing area | region, 130 ... Button, 140 ... Input object, 200 ... Input device, 202 ... Power supply, 204 ... -Host, 206 ... Display source, 208 ... Chassis ground, 210, 212 ... Switch, 211 ... Reference voltage rail, 214 ... Bypass capacitor, 216 ... Local ground, 218 ... Control signal, 220 ... Timing controller, 222 ... Sensor module, 224 ... Display module, 226 ... Reference voltage modulator, 228 ... Modulation signal, 230 ... Power management controller, 231 ... Panel power supply, 232 ... Backlight, 234 ... Display / sensing panel, 235 ... Sensor control signal, 236 ... Display Path 240 ... display electrode 242 ... sensor electrode 244 ... high speed link 300 ... input device 305 ... non-modulated power domain 310 ... modulated power domain 315 ... Voltage regulator, 320 ... high-speed data interface, 325 ... receiver, 340 ... link, 400 ... input device, 405 ... capacitor, 410 ... reference voltage modulator, 415 ... Transmitter, 500 ... integrator, 515 ... signal generator, 520 ... resistor, 525 ... capacitor, 710, 720, 730 ... sensor electrode, 800 ... input device, 805 ... Timing controller, 810 ... Central receiver, 815 ... Local receiver, 1100 ... System, 1105 ... Input device, 1110 ... Input device 1115 ... grounding point, 1120 ... sensing area, 1125 ... grounding state, 1200 ... input device, 1205 ... central receiver, 1210 ... local receiver, 1405 ...・ Environment, 1410: Back plate chassis, 1420: Current conveyor,

Claims (22)

A plurality of sensor electrodes;
A plurality of display electrodes;
A processing system,
The processing system includes:
A plurality of local receivers each coupled to a corresponding one of the plurality of sensor electrodes, the local receiver configured to obtain a first result signal from the plurality of sensor electrodes;
A central receiver coupled to the plurality of sensor electrodes and configured to simultaneously acquire a second result signal from each of the plurality of sensor electrodes.   The input device according to claim 1, wherein the central receiver is coupled to a constant reference voltage and is unmodulated when obtaining the second result signal.   The input device according to claim 2, wherein the central receiver comprises an amplifier, and the input of the amplifier is coupled to the reference voltage when obtaining the second result signal.   The input of claim 1, wherein all of the sensor electrodes are coupled to a common electrical node and the central receiver is coupled to the common electrical node to obtain the second result signal. apparatus.   The input device of claim 1, wherein the processing system is configured to identify an interference measurement based on the second result signal.   The input device according to claim 1, wherein the processing system is configured to identify a communication signal transmitted by an active input object external to the input device based on the second result signal.   The input device of claim 1, further comprising a switch configured to selectively disconnect a display from a power source when the central receiver obtains the second result signal.   8. The input device of claim 7, further comprising a capacitive power storage element coupled to the power source through the switch, wherein the capacitive power storage element is charged by the power source when the switch is activated.   And further comprising a display module configured to update the display using charges stored in the capacitive power storage element, wherein the display module is in parallel with obtaining the second result signal. The input device of claim 8, wherein the display is at least partially updated.   The input device according to claim 1, wherein the central receiver is configured to acquire a third result signal from each of the display electrodes, and the second and third result signals are acquired in parallel. . A plurality of local receivers coupled to corresponding ones of the plurality of sensor electrodes, the local receiver configured to receive a first result signal from the sensor electrodes;
A processing system comprising a central receiver coupled to the sensor electrode and configured to simultaneously acquire a second result signal from each of the sensor electrodes.   12. The processing system of claim 11, wherein the central receiver is coupled to a constant reference voltage and is unmodulated when acquiring the second result signal.   The processing system of claim 12, wherein the central receiver comprises an amplifier, and the input of the amplifier is coupled to the reference voltage when obtaining the second result signal.   The processing system of claim 11, wherein the central receiver is configured to identify at least one of interference measurements based on the second result signal.   12. The processing system of claim 11, wherein the central receiver is configured to identify a communication signal transmitted by an active input object external to the input device based on the second result signal.   The processing system of claim 11, further comprising a switch configured to selectively disconnect a display from a power source when the central receiver obtains the second result signal.   17. The capacitive power storage element configured to be coupled to the power source through the switch, the capacitive power storage element being charged by the power source when the switch is activated. Processing system.   The processing system of claim 11, wherein the central receiver is configured to acquire a third result signal from each of the display electrodes, and the second and third result signals are acquired in parallel. Receiving a first result signal at a plurality of local receivers from a plurality of sensor electrodes to perform capacitive sensing, each of the local receivers being coupled to a corresponding one of the sensor electrodes;
Receiving a second result signal from the sensor electrode at a central receiver, the central receiver being coupled to the sensor electrode;
A method involving that.   Prior to receiving the second result signal, further comprising electrically disconnecting the display from a power source, wherein the sensor electrode is unmodulated when receiving the second result signal at the central receiver. 20. The method of claim 19, wherein:   The method of claim 19, further comprising identifying at least one of interference measurements based on the second result signal.   20. The method of claim 19, further comprising identifying a communication signal transmitted by an active input object external to the input device based on the second result signal.