Patent Description:
A grid based capacitive sensor is one type of digitizer sensor that may be integrated with an electronic display of the computing device to form the touch sensitive screen and may also be used on a trackpad. Grid based capacitive sensors typically track free style input provided with an object such as a finger or a conductive object with a mutual capacitive or self-capacitive detection method. During both mutual capacitive detection and self-capacitive detection, a circuit associated with the digitizer sensor transmits a drive signal on one or more grid lines of the digitizer sensor and detects a capacitive load in response to the drive signal. The circuit may also be configured to detect signals emitted by a stylus and track position of the stylus. The digitizer sensor together with the associated circuit is a digitizer system. Coordinates of the tracked object (stylus and finger) may be reported to the computing device and interpreted as user commands or user inputs for commands.

The <CIT> discloses a method that includes detecting a signal emitted by a stylus with a digitizer sensor, determining coordinates of the stylus, identifying a hover operational mode based on input received by the stylus, detecting a capacitive effect of a tip of the stylus on the digitizer sensor and reporting a touch operational mode of the stylus based on the capacitive effect detected. The capacitive effect of the tip of the stylus on the digitizer sensor is based on mutual capacitive detection and is performed in a defined area around the coordinates determined.

Furthermore, the <CIT> that discloses a method that includes sampling output from a sensor having electrode junctions integrated on a device including a display, detecting capacitance between the device ground and a user based on the output sampled and a pre-defined model, and defining one of two grounding states of the device based on the capacitance detected. Output is processed based on the grounding state defined and touch coordinates are determined based on the output processed. The touch coordinates are reported to a controller of the display.

Additionally, <CIT> discloses a capacitive touch device and a method for identifying a touch object and performing a palm rejection operation, wherein a sensing information includes a sensing cluster corresponding to a portion on the touch panel touched by the touch object.

Moreover, <CIT> discloses a method that includes determining, based on output from a sensor, a proximity of an object to a device and comparing the determined proximity to a threshold proximity. Environmental noise can be used for touch sensing.

According to example implementations of the disclosure there is provided a method as claimed in claim <NUM>. The method may be implemented whenever the computing device with the touch sensitive surface is in an ungrounded state. An ungrounded state may occur while the computing device is not connected to a power supply with a three- prong connector and is not being gripped by the user. While the computing device is ungrounded, the stylus signal may find a path to ground via the user and the stylus signal transmitted through the user may appear at touch locations on the screen. According to example implementations, a digitizer system is configured to detect a stylus signal injected through the user on the digitizer sensor and recognize the input as touch input.

According to example implementations, the digitizer system monitors the grounding state of the device and implements the method when the device is determined to be ungrounded and a signal, e.g. a stylus signal is be detected. According to example implementations, the method improves palm rejection and also provides touch detection with lower power consumption and higher refresh rate. Optionally, a similar method may be implemented over a sampling window dedicated to detect noise and touch may be identified based on noise input being induced on a user touching the touch sensitive surface, e.g. touch sensitive screen or trackpad while the device is ungrounded.

Unless otherwise defined, all technical and/or scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of embodiments of the disclosure, exemplary methods and/or materials are described below.

Some embodiments of the disclosure are herein described, by way of example only, with reference to the accompanying drawings. With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of embodiments of the disclosure. In this regard, the description taken with the drawings makes apparent to those skilled in the art how embodiments of the disclosure may be practiced.

According to some example implementations, a digitizer system detects touch input on a touch sensitive surface based on output in a frequency range of the stylus. While the computing device is ungrounded, the stylus signal may find a path to ground via the user and the stylus signal transmitted through the user may appear at touch locations on the screen. According to some example implementations, these touch locations may be identified by the digitizer system and differentiated from a stylus signal detected at a location near a writing tip of the stylus. The touch locations may be detected over a sampling window dedicated for stylus detection, e.g. together with stylus detection. The differentiation may be based on gain of the output as well as shape of a spread of the output over the sensing surface.

According to some example implementations, touch detection in a frequency range of the stylus is implemented for palm rejection. Palm input is typically difficult to detect based on mutual capacitive detection while the computing device is ungrounded. Due to a known retransmission effect, the relatively large touch area of the palm (large blob) may appear as a plurality of smaller touched areas (smaller blobs) that may be falsely identified as finger touch input. Palm detection based on the stylus signal injected through the user does not suffer from the retransmission effect and therefore the blob associated with palm input corresponds to the shape and size of the palm contact and may be clearly recognized as palm input.

According to some example implementations, touch detection in a frequency range of the stylus is implemented for touch tracking of single touch while the computing device is ungrounded. Tracking touch based on detecting the injected stylus signal may be faster, less processing heavy, and performed with less power expenditure than touch tracking based on mutual capacitive detection. In some example embodiments, the digitizer system may temporarily suspend mutual capacitive detection or may temporarily reduce the refresh rate of mutual capacitive detection while the computing device is determined to be ungrounded and the conditions are suitable for touch detection based detection in a frequency range of the stylus. The digitizer system may in this case track the single touch input simultaneously with stylus detection, e.g. over the same sampling window. Since scanning is not typically needed for stylus signal detection, detection is quicker and the refresh rate may optionally be increased. Optionally, touch detection in a frequency range of the stylus is synchronized with transmission of the stylus signal.

In some example implementations, touch input may be detected on an ungrounded touch sensitive surface based on output in a frequency range of noise in the surrounding environment. For example, noise from florescent lighting or from a two-prong power supply (ungrounded power supply) may be injected through the user and appear at touch locations while the user is interacting with the touch sensitive surface. These touch locations may be tracked while detecting output in a broad frequency band or at frequency bands specified for noise detection. Optionally, touch detection based on noise frequency may be detected in a sampling window at which the expected noise is typically detected. Touch locations may be differentiated from general noise based on gain and shape of a spread of the output over the sensing surface. Optionally, touch detection based on output in a noise frequency range may be performed without stylus transmission.

For purposes of better understanding some embodiments of the present invention, as illustrated in <FIG> of the drawings, reference is first made to the construction and operation of a computing device as illustrated in <FIG>.

Reference is now made to <FIG> showing a simplified block diagram of an exemplary touch and pen enabled computing device and to a simplified timeline of example sampling windows for sampling a grid based capacitive sensor. Computing device <NUM> includes a display <NUM> integrated with a digitizer sensor <NUM>. Sensor <NUM> may be operated to detect both input by stylus <NUM> and to detect a finger effect due to one or more fingertips <NUM> or other conductive objects interacting with sensor <NUM>. Palm input from hand <NUM> positioned over or resting on sensor <NUM> may also be detected. Digitizer sensor <NUM> typically includes a matrix formed with parallel conductive material <NUM> arranged in rows and columns with a capacitive connection in junction areas <NUM> formed between rows and columns. Digitizer sensor <NUM> may be operated by digitizer circuit <NUM> and may be in communication with host <NUM>. Optionally, sensor <NUM> may not be integrated with display <NUM> and may be instead integrated with an alternate sensing surface, e.g., a trackpad.

Digitizer circuit <NUM> applies mutual capacitive detection or a self-capacitive detection for sensing a touch signal from touch (or hover) of fingertip <NUM>. Typically, mutual capacitive detection provides for detecting coordinates of multiple fingertips <NUM> touching sensor <NUM> at the same time (multi-touch). Bringing a grounded finger <NUM> close to the surface of digitizer sensor <NUM> changes the local electrostatic field and reduces the mutual capacitance at junctions <NUM> in the touched area. A change in mutual capacitance may be detected by circuit <NUM> when applying a drive signal along one axis (the drive lines) of the matrix while sampling output on the other axis (the receive lines) to detect a coupled signal. Mutual capacitive detection may be performed over one or more sampling windows <NUM> (<FIG>) for each refresh cycle, Tcycle, of digitizer circuit <NUM>. Typically, a plurality of sampling windows <NUM> is defined to provide for scanning the entire area of sensor <NUM> one drive at a time or a plurality of drive lines at a time based on mutual capacitive detection.

Finger touch generally has the effect of reducing amplitude of the measured signal. Output from digitizer sensor <NUM> may be in the form of a heatmap that maps detected amplitudes of the coupled signals at each junction <NUM>. In a heatmap, finger touch produces a negative blob at the touch location. When part of hand <NUM> (palm) hovers or rests on digitizer sensor <NUM>, a negative blob may also be recorded due to palm input.

Digitizer circuit <NUM> may also detect input from a stylus <NUM> emitting a signal <NUM> from its tip <NUM>, e.g. writing tip. Stylus <NUM> may also emit a signal from a ring <NUM> around its tip <NUM> and from an eraser end <NUM> of stylus <NUM>. Digitizer circuit <NUM> may also detect input from ring <NUM> and eraser end <NUM>. During stylus detection, digitizer circuit <NUM> may simultaneously sample conductive material <NUM> forming both the rows and columns to detect signals <NUM> picked up by conductive material <NUM> near writing tip <NUM> (ring <NUM> or eraser end <NUM>). Digitizer circuit <NUM> may detect stylus input over a dedicated stylus sampling window <NUM> (<FIG>) in which both column and row conductive material <NUM> (drive and receive lines) are sampled.

Signal <NUM> may be a pulsed signal transmitted at a defined repeat rate, e.g. every <NUM>-<NUM> msec. The pulsed signal may include a position signal (or beacon) and optionally a train of data defining a plurality of parameters. Optionally, stylus <NUM> is pressure sensitive and the data includes information indicating that the stylus is in one of a hover or touch operational mode. In some example embodiments, the data is based on a pressure sensor associated with writing tip <NUM> (or eraser end <NUM>). Optionally, a separate sampling window may be defined to detect the train of data. Synchronization may be established between transmission of signal <NUM> and stylus sampling window <NUM>. Optionally, digitizer circuit <NUM> synchronizes with transmissions of signal <NUM> and stylus sampling window <NUM> is adjusted based on timings of signal <NUM>. Optionally, while digitizer circuit <NUM> is searching for stylus signal <NUM> more than one stylus sampling window <NUM> is defined per refresh cycle, Tcycle, of digitizer circuit <NUM>.

Digitizer circuit <NUM> may sample output in a frequency band of the drive signal over mutual capacitive detection sampling windows <NUM> and may sample output in a frequency band of an expected stylus signal over stylus detection windows <NUM>. Optionally, digitizer circuit <NUM> may also operate additional sampling windows such as noise sampling windows <NUM>. Optionally, a frequency band for sampling over noise sampling window <NUM> may be defined over a wider frequency band that may include both frequency band of the drive signal and frequency band of an expected stylus signal.

Output from digitizer circuit <NUM> is reported to host <NUM>. Typically, the output provided by digitizer circuit <NUM> includes coordinates of one or more fingertips <NUM> and coordinates of writing tip <NUM> when present. Digitizer circuit <NUM> may be configured to differentiate between input from fingertip <NUM> and input from hand <NUM> and may selectively refrain from reporting coordinates of hand <NUM> based on a defined palm rejection method. Additional information related to parameters of stylus <NUM>, noise being picked up by sensor <NUM> and a grounding state of device <NUM> may also be detected with digitizer circuit <NUM> based on input from digitizer sensor <NUM>. The additional information detected may be reported to host <NUM>. Digitizer circuit <NUM> may distinguish between input received by hover or touch and may report one of a hover or touch state to host <NUM> together with the detected coordinates of the input. Optionally, some or all of the functionalities of digitizer circuit <NUM> may be integrated into host <NUM>.

<FIG> shows a schematic representation of the relative effect on a grid based capacitive sensor with one finger touching the digitizer sensor. Only a portion of digitizer sensor <NUM> is shown for simplicity. A presence of a fingertip <NUM> at location <NUM> reduces mutual capacitance at junctions <NUM> in location <NUM>. Due to the reduced mutual capacitance, when a drive signal <NUM> is imposed on drive lines <NUM>, amplitudes detected on the touched receive lines <NUM> are lower than amplitude detected on other receive lines <NUM>. Reduced amplitudes due to the reduced mutual capacitances are represented by arrows <NUM>.

At the same time, potential may be induced on the finger from drive signal <NUM>. This typically occurs while the device is not grounded due to the difference in potential between the user that is grounded and the device. The potential induced on the finger from drive signal 305may be injected on receive lines <NUM> which increases amplitudes of the outputs as represented by arrows <NUM>. The output detected from the touched receive lines is therefore a summation of amplitude <NUM> and amplitude <NUM>. Typically, output detected from a single finger touch produces a negative blob having amplitude that varies based on the magnitude of the induced potential. This amplitude sometimes called the finger effect may be used as an indication of a grounding state of the computing device. Low amplitude, e.g. below a defined threshold, due to large induced potential may indicate that the device is ungrounded while high amplitude, e.g. above the defined threshold, due to a small induced potential may indicate that the device is grounded. A grounding state of the device may be monitored by digitizer circuit <NUM> (<FIG>) and optionally reported to host <NUM>.

<FIG> show example heatmaps and corresponding two dimensional blobs of example palm touch signal for a device that is grounded and ungrounded respectively. Heatmaps <NUM> and <NUM> show absolute values for amplitude. Relatively large touch areas such as a touch area due to a hand resting on the digitizer sensor may be further affected by the grounding state of the device as compared to a single finger touch. While a computing device is well grounded, a palm touch area may appear as a well defined peak in heat map <NUM> and blob <NUM> defined by heat map <NUM> may appears as a single area that may be clearly distinguished from single finger touch input. However, when a computing device has high impedance to ground, e.g. is ungrounded, a same palm input may produce a heatmap, e.g. heatmap <NUM> that provides a peak that is not well defined. Distortions in heat map <NUM> are due to coupling of potentials picked up by the palm that reverse the effect of the touch signal. These distortions may lead to a single palm touch area being depicted as a plurality of separate blobs <NUM>, <NUM>, <NUM>. Digitizer circuit <NUM> (<FIG>) may mistakenly identify the palm input as three close finger touches based on heatmap <NUM>.

Reference is now made to <FIG> showing a simplified schematic drawing of example simultaneous stylus and palm input to a device and schematic representations of corresponding example outputs when the device is grounded and ungrounded respectively in accordance with some example embodiments of the disclosure. While a user is providing input with stylus <NUM>, a hand <NUM> holding stylus <NUM> or optionally the opposite hand of the user may be resting on sensor <NUM>. As long as device <NUM> is well grounded, output detected over stylus sampling window <NUM> (<FIG>) is not affected by contact of hand <NUM> on sensor <NUM> as shown in <FIG>. Device <NUM> may be well grounded while connected to a power supply with a three-prong connector or based on a user physically contacting a chassis of the device. While device <NUM> is grounded, output detected may typically show a sharp peak in amplitude <NUM> in both the row and column conductive material <NUM> that indicate stylus input at location <NUM>. Peaks <NUM> may be less sharp when stylus <NUM> is hovering as opposed to touching device <NUM>.

<FIG> shows example output detected over stylus sampling window <NUM> while device <NUM> is ungrounded. Device <NUM> may be ungrounded while connected to power supply with a two-prong connector or while the device is resting on non-conductive surface. While device <NUM> is not grounded, physical contact between hand <NUM> and stylus <NUM> may induce a potential on hand <NUM> in a frequency band of signal <NUM> (from writing tip <NUM>, ring <NUM> or eraser <NUM>). Contact of hand <NUM> in a vicinity of conductive strips <NUM> picking up signal <NUM> may also induce a potential on hand <NUM> in the frequency band of signal <NUM>. Due to the induced potential, output <NUM> on each of the row and column conductive materials <NUM> in an area <NUM> of hand touch that may be detected in the stylus sampling window <NUM>. Amplitude of output <NUM> due to hand <NUM> picking up potential from signal <NUM> is typically significantly lower in amplitude as compared to output <NUM> detected on sensor <NUM> directly from stylus <NUM>. Amplitude <NUM> is not expected to differ significantly between a grounded and ungrounded state of the device when using a non-conductive housing for the stylus due to the relatively high impedance between the user and the stylus.

According to some example embodiments, digitizer circuit <NUM> is configured to detect both stylus input and hand input over a stylus sampling window <NUM> and to distinguish between them. In some example embodiments, stylus input is identified as a peak spread over a defined number of conductive strips <NUM> and having amplitude above a defined stylus amplitude threshold, while hand input is identified as a peak spread over a larger number of conductive strips <NUM> and having amplitude in a defined range below the defined stylus amplitude threshold.

In some example embodiments, touch detection over the stylus sampling window, e.g. in the stylus frequency range is applied to track palm input and to perform palm rejection while device <NUM> is in an ungrounded state, e.g. poorly grounded. Since output <NUM> (<FIG>) is not detected while drive signals are transmitted on sensor <NUM> and the output does not suffer from distortions due to potentials picked up by the palm having a reverse the effect of the touch signal. Digitizer circuit <NUM> may classify size and shape of area <NUM> and determine that area <NUM> is palm input based on the classification. In some example embodiments, a heatmap, e.g. heatmap <NUM> (<FIG>) detected over a mutual capacitive sampling window may be verified as input from a palm based on comparing location of touch inputs in the heatmap detected over the mutual capacitive sampling periods <NUM> with location of area <NUM> (<FIG>) detected over the stylus sampling period <NUM>.

Reference is now made to <FIG> showing a simplified schematic drawing showing example simultaneous stylus and finger touch input to a device and schematic representations of corresponding example outputs from stylus detection when the device is ungrounded in accordance with some example embodiments of the disclosure. In some example embodiments, while one hand <NUM> is holding stylus <NUM>, signal <NUM> may induce a potential on a user that may be detected on sensor <NUM> when one or more fingertips <NUM> from the opposite hand simultaneously touches sensor <NUM>. This may occur while device <NUM> is in an ungrounded state. In some example embodiments, a distinct peak <NUM> may be detected in the row and column direction for each finger touch over a stylus sampling window. However, coordinates of multiple touches may not always be resolvable based on output <NUM>. For example touch of two fingers <NUM> may correspond to four potential touch locations <NUM> based on outputs <NUM> two of which may be the touch locations and two others may be ghost locations.

In some example embodiments, digitizer circuit <NUM> may define an inclusive area <NUM> including all potential touch locations <NUM> and may use this information during mutual capacitive detection. Optionally, digitizer circuit <NUM> may reduce an area that is scanned during mutual capacitive detection (optionally only scan area <NUM>) based on area <NUM> detected over the stylus sampling window <NUM>. Optionally, by reducing the number of drive lines that are scanned, the number of mutual capacitive detection sampling windows <NUM> may be reduced. Optionally reducing refresh rate.

Reference is now made to <FIG> showing a simplified schematic drawing of an example simultaneous stylus and single touch input to a device and schematic representations of corresponding example outputs from stylus detection when the device is ungrounded in accordance with some example embodiments of the disclosure. According to some example embodiments, during an ungrounded state of device <NUM>, stylus input <NUM> along with single touch input <NUM> may be detected over a stylus sampling window <NUM>. Single touch input <NUM> may be detected based on potential induced on finger <NUM> touching sensor <NUM> while an opposite hand <NUM> is holding stylus <NUM>. In some example embodiments, digitizer circuit <NUM> detects single touch <NUM> input over a stylus sampling window and may report coordinates of touch <NUM> based on output <NUM> detected over stylus sampling window <NUM>. Optionally, digitizer circuit <NUM> may reduce the number or the frequency of mutual capacitive detection sampling windows <NUM> while detecting a single touch <NUM> is stylus sampling window <NUM>. Optionally, while device <NUM> is determined to be ungrounded, digitizer circuit <NUM> may also reduce the number of sampling windows <NUM> or the refresh rate of mutual capacitive detection when no touch area <NUM> is detected over stylus sampling period <NUM>.

Reference is now made to <FIG> showing a simplified schematic drawing of an example single-touch input on a device and schematic representations of corresponding example outputs from stylus detection when the device is ungrounded in accordance with some example embodiments of the disclosure. In some example embodiments, touch with fingertip <NUM> may be detected on sensor <NUM> over a stylus detection period <NUM> even when the user is not holding stylus <NUM>. For example stylus <NUM> may be laying over sensor <NUM> or adjacent to sensor <NUM>. Optionally, as long as stylus <NUM> is emitting signal <NUM> in a vicinity of sensor <NUM> (by hovering or touching the touch screen), a potential from signal <NUM> may be induced on fingertip <NUM> touching sensor <NUM> while device <NUM> is in an ungrounded state. In some example embodiments, touch <NUM> may be detected based on output <NUM> detected over stylus sampling period <NUM>. Amplitude of peaks in output <NUM> may be lower during a hover mode of stylus <NUM>, e.g. while the writing tip or eraser end is not touching sensor <NUM>. In some example embodiments, a threshold for detecting touch <NUM> may be reduced during a hover operational mode. Optionally, the digitizer system may differentiate between a hover and touch mode of stylus <NUM>, e.g. based on a sensor in stylus <NUM>. The threshold for detecting touch <NUM> may be reduced based on information received from stylus <NUM>.

Reference is now made to <FIG> showing a simplified schematic drawing showing example single-touch input to a device and schematic representations of corresponding example outputs from noise detection when the device is ungrounded in accordance with some example embodiments of the disclosure. In some example embodiments, touch may be detected over various sampling windows, e.g. other than the stylus sampling window <NUM> and other than the mutual capacitive detection sampling window <NUM>. In some examples, touch may also be detected over a noise sampling window <NUM> as long as device <NUM> is in an ungrounded state. In some example embodiments, device <NUM> may be exposed to noise, e.g. noise from florescent lighting or from a two-prong power supply (ungrounded power supply) and potential from this noise may be induced on fingertip <NUM> (or hand <NUM>) touching sensor <NUM> while device <NUM> is ungrounded. The induced potential from the noise may provide a touch signal in the noise sampling period as long as the noise is in a frequency range sampled. Optionally, digitizer circuit <NUM> may detect and track finger touch <NUM> based on output <NUM> detected in the noise window.

Reference is now made to <FIG> showing a simplified block diagram of an exemplary computing device including a touch and pen enabled trackpad in accordance with some embodiments of the present disclosure. According to some example embodiments, a device <NUM> may include a trackpad <NUM> as a touch sensitive surface that is both touch and pen enabled. Optionally, display <NUM> of device <NUM> may or may not be touch and pen enabled. Trackpad <NUM> may include a grid based capacitive sensor that may be sensitive to a grounding state of device <NUM>. According to some example implementations, the methods described herein to detect touch and perform palm rejection may be similarly applied to track touch and perform palm rejection on trackpad <NUM>.

Reference is now made to <FIG> showing a simplified flow chart of an example method for selectively using output from stylus sampling window for palm rejection in accordance with some example embodiments of the disclosure. In some example embodiments, a grounding state of a touch and pen enabled device is monitored (block <NUM>). Optionally, the device includes a grounding state machine that may detect a grounding state of the device based on relative effects of selected output detected with mutual capacitive detection. In some example embodiments, as long as the device is determined to be grounded (block <NUM>), touch input may be detected over sampling windows dedicated to mutual capacitive detection (block <NUM>). Palm rejection may be based on size and shape of touch area detected during mutual capacitive detection (block <NUM>). Stylus input may be detected over a dedicated stylus sampling window (block <NUM>). Output of the sensor over the stylus sampling window is sampled in a frequency of a signal transmitted by the stylus. Coordinates of finger touch, e.g. intended touch and stylus may be reported to the host computer (block <NUM>).

In some example embodiments, while the device is determined to be ungrounded (block <NUM>), touch may still be tracked with mutual capacitive detection (block <NUM>) and but may also be tracked over a stylus sampling window together with tracking stylus input (block <NUM>). Optionally, the refresh rate for mutual capacitive detection may be reduced while the device is determined to be ungrounded. In some example embodiments, palm rejection may be performed or verified based on touch detected in the stylus sampling window (block <NUM>). Coordinates of finger touch, e.g. intended touch and stylus may be reported to the host computer (block <NUM>).

Reference is now made to <FIG> showing a simplified flow chart of an example palm rejection method based on output from stylus sampling window in accordance with some example embodiments of the disclosure. In some example embodiments, touch input may be identified based on output from the stylus sampling window, e.g. output in a frequency range of the stylus signal. In some example embodiments, a touch signal is distinguished from a stylus signal based on amplitude of the output. Output due to touch may be expected to have a lower amplitude and be spread over more conductive lines of the grid based sensor as compared to output due to a stylus tip (eraser end or ring around tip) interacting with the digitizer sensor. In some example embodiments, size of the touch area (block <NUM>) and a shape characteristic of the touch area (block <NUM>) may be detected and palm may be identified based on classification of the size and shape detected (block <NUM>). Optionally, palm input may be rejected, e.g. its location may not be reported to the host computer (block <NUM>).

Reference is now made to <FIG> showing a simplified flow chart of an example method for touch and stylus detection in accordance with some example embodiments of the disclosure. In some example embodiments, a grounding state of a touch and pen enabled device is monitored (block <NUM>). In some example embodiments, as long as the device is determined to be grounded (block <NUM>), touch input may be detected over sampling windows dedicated to mutual capacitive detection and at a standard refresh rate(block <NUM>). Stylus input may be tracked substantially simultaneously over dedicated stylus sampling windows (block <NUM>). Touch and stylus location may be reported to the host computer (block <NUM>).

In some example embodiments, while the device is determined to be ungrounded (<NUM>) and single touch input is identified (block <NUM>), a refresh rate for mutual capacitive detection may be reduced (block <NUM>) and touch tracking may be performed or supplemented based on output from stylus sampling window as long as a stylus signal is being received by the digitizer sensor. Both touch and stylus may be detected over the stylus sampling window (block <NUM>). Touch and stylus location may be reported to the host computer (block <NUM>).

Reference is now made to <FIG> showing a simplified flow chart of an example method for touch detection in accordance with some example embodiments of the disclosure. In some example embodiments, a grounding state of a touch and pen enabled device is monitored (block <NUM>). In some example embodiments, as long as the device is determined to be grounded (block <NUM>), touch input may be detected over sampling windows dedicated to mutual capacitive detection (block <NUM>). Palm rejection may be based on size and shape of touch area detected during mutual capacitive detection (block <NUM>) and noise may be monitored over dedicated noise sampling windows (block <NUM>). Finger touch locations, e.g. intended touch may be reported to the host computer (block <NUM>).

In some example embodiments, while the device is determined to be ungrounded (block <NUM>), touch input may still be detected over mutual capacitive sampling windows and may also be detected together with noise over noise sampling windows (block <NUM>). Palm rejection may be performed or verified based on touch input detected in the noise sampling window (block <NUM>). Optionally, touch may be tracked together with noise monitoring based on output detected over the noise sampling window (block <NUM>).

According to an aspect of some example embodiments, there is provided a method comprising: sampling output in a frequency range of a signal emitted from a stylus over a stylus sampling window, wherein the sampling is performed simultaneously from both columns and rows of a grid based capacitive sensor; detecting stylus input based on detecting a gain above a stylus threshold in at least one column and one row of the sensor; reporting coordinates of the stylus based on stylus input being detected; detecting touch input from a finger or hand based on detecting a gain between a touch threshold and a stylus threshold, wherein the touch threshold is below the stylus threshold over at least two consecutive columns and two consecutive rows of the sensor; and reporting coordinates of the touch input based on detecting the touch input.

Optionally, the method includes determining that a device including the grid based capacitive sensor is either grounded or ungrounded; and detecting the touch input from the finger or hand based on the output in the stylus frequency range only when the device is ungrounded.

Optionally, the method includes performing mutual capacitive detection; determining gains of selected touch areas detected over the mutual capacitive detection; determining that the device either grounded or ungrounded based on the gains.

Optionally, the method includes detecting a heatmap on the grid based capacitive sensor based on mutual capacitive detection; identifying a plurality of blobs on the heatmap; comparing an area of the touch input detected over the stylus sampling window with the plurality of blobs identified in the heatmap; and reporting the coordinates of the touch input based on the comparing.

Optionally, the method includes performing palm rejection based on the comparing and refraining from reporting coordinates of the palm input.

Optionally, the method includes determining size of the touch input; and
identifying the touch input as palm input based on the size.

Optionally, the method includes determining a shape characteristic of a spread of the touch input over the sensor; and identifying the touch input as palm input based on the size.

Optionally, the method includes identifying a single area of the touch input over the stylus sampling window; and reducing a refresh rate for mutual capacitive detection of the sensor based on identifying the single area of the touch input.

Optionally, the method includes identifying a single area of the touch input over the stylus sampling window; and temporarily suspending mutual capacitive detection of the sensor based on identifying the single area of the touch input.

Optionally, the method includes identifying a plurality of touch inputs over a defined area over the stylus sampling window; and performing mutual capacitive detection of the sensor only over the defined area.

According to an aspect of some example embodiments, there is provided a method including determining that a device that includes a grid based capacitive sensor is either grounded or ungrounded; and sampling output of the grid based capacitive sensor over a plurality of sampling windows; performing mutual capacitive detection over a first sampling window from the plurality; sampling output from both columns and rows of the grid based sensor over a second sampling window from the plurality, wherein the output is sampled without driving the column or rows with a driving signal emitted by a controller configured to operate the grid based capacitive sensor; identifying a heatmap based on the mutual capacitive detection over the first sampling window; identifying areas of touch input from the output sampled over the second sampling window based on determining that the device is ungrounded; comparing the heatmap to the areas of touch input identified based on determining that the device is ungrounded; and reporting coordinates of touch based on the comparing.

Optionally, the second sampling window is a sampling window configured for tracking a stylus, wherein the stylus is configured to transmit a signal.

Optionally, the second sampling window is a sampling window configured for sampling a noise environment of the grid based capacitive sensor.

Optionally, the output sampled over the second sampling window is in a frequency range of noise from a power supply that is not grounded or in a frequency range of noise based on fluorescent lights.

Optionally, the method includes performing palm rejection based on identifying the areas of touch input from the output sampled over the second sampling window.

Optionally, the method includes determining a size of the areas of the touch input from the output sampled over the second sampling window; determining a shape characteristic of a spread over the sensor of the areas of the touch input from the output sampled; and identifying at least one of the areas as palm input based on the shape.

Optionally, the method includes identifying a plurality of blobs on the heatmap; comparing the areas of the touch input detected over the second sampling window with the plurality of blobs identified in the heatmap; and reporting the coordinates of the touch input based on the comparing.

Optionally, the includes identifying at least a portion of the plurality of blobs as palm input based on the comparing and refraining from reporting coordinates of the palm input.

Optionally, the method includes identifying a single area of the touch input over the second sampling window; and reducing a number of sampling windows in which mutual capacitive detection is performed over subsequent refresh periods based on identifying the single area of the touch input.

Claim 1:
A method comprising:
determining that a device that includes a grid based capacitive sensor (<NUM>) is either grounded or ungrounded; and
sampling the output of the grid based capacitive sensor (<NUM>) over a plurality of sampling windows (<NUM>);
performing mutual capacitive detection over a first sampling window from the plurality of sampling windows (<NUM>);
sampling the output from both columns and rows of the grid based capacitive sensor (<NUM>) over a second sampling window from the plurality of sampling windows (<NUM>), wherein the output is sampled without driving the column or rows with a driving signal emitted by a controller configured to operate the grid based capacitive sensor (<NUM>) and wherein the grid based capacitive sensor (<NUM>) is either driven by a stylus (<NUM>) or by noise;
identifying a heatmap (<NUM>; <NUM>) based on the mutual capacitive detection over the first sampling window;
identifying areas of touch input from the output sampled over the second sampling window based on determining that the device (<NUM>) is ungrounded;
comparing the heatmap to the areas of touch input (<NUM>) identified based on determining that the device is ungrounded;
reporting the coordinates of the touch based on the comparing; and
performing palm rejection based on the comparing and refraining from reporting coordinates of a palm input.