Suppression of noise in contact fields using a shielding layer

Abstract

A procedure (1100) that includes the following: Measuring (1102) on a first channel (224A) of a processing device (116) a first signal (234) indicating a touch object (102) near a first electrode layer (106), wherein the first signal (234) includes a touch data component and a first noise component (232A) generated by a noise source (112); Measuring (1104) on a second channel (224B) of the processing device (116) a second signal (236) which includes a second noise component (232B) generated by the noise source (112), wherein the second channel (224B) is coupled to a second electrode (108); Generating (1106) an estimated noise signal using the second noise component (232B) of the second signal (236) associated with the second channel (224B), wherein the estimated noise signal is an estimate of the first noise component (232A) of the first signal (234); and Subtracting (1108) the estimated noise signal from the measured first signal (234) to obtain the touch data component of the first signal (234).

Description

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[0001] This application is an international application of US patent application number 16 / 122,014, filed on September 5, 2018, claiming the benefit of provisional US patent application number 62 / 557,472, filed on September 12, 2017, all of which are hereby incorporated by reference in their entirety. AREA OF INVENTION

[0002] The present disclosure relates generally to detection systems and in particular to capacitance measurement systems that are configurable to suppress noise in contact fields using shielding layers. STATE OF THE ART

[0003] Capacitive sensing systems can detect electrical signals generated at electrodes that reflect changes in capacitance. Such changes in capacitance can indicate a touch event (i.e., the proximity of an object to specific electrodes). Capacitive sensing elements can be used to replace mechanical buttons, knobs, and other similar mechanical user interface controls. Using a capacitive sensing element eliminates the need for complex mechanical switches and buttons, providing reliable operation in harsh environments. Furthermore, capacitive sensing elements are widely used in modern consumer applications, providing user interface options in existing products.Capacitive sensing elements can range from a single button to a large number grouped in the form of a capacitive sensing arrangement for a touch sensing surface of a touch field.

[0004] Capacitive sensing devices and touch buttons are ubiquitous in today's industrial and consumer markets. They can be found on mobile phones, GPS devices, set-top boxes, cameras, computer monitors, MP3 players, digital tablets, and the like. Capacitive sensing devices work by measuring the capacitance of a capacitive sensing element and checking for a change in capacitance that indicates touch or the presence of a touchable object. When a touchable object (such as a finger, hand, or other conductive object) comes into contact with or near a capacitive sensing element, the capacitance changes, and the conductive object is detected. These capacitance changes can be measured by an electrical circuit. The electrical circuit converts the signals corresponding to the measured capacitances of the capacitive sensing elements into digital values.The measured capacities are generally received as currents or voltages, which are integrated and converted into digital values.

[0005] There are two typical types of capacitance: 1) counter-capacitance, wherein the capacitance sensing circuit measures a capacitance formed between two electrodes coupled to the capacitance sensing circuit; 2) self-capacitance, wherein the capacitance sensing circuit measures a capacitance of an electrode. A touch field can exhibit a distributed capacitance load of both types (1) and (2), and some touch solutions detect both capacitances either separately or in combination with their various sensing modes. Furthermore, the disclosures of US 2011 / 0 285 654 A1, US 2016 / 0 018 921 A1, and DE 11 2016 005 279 T5 may be helpful for understanding the present invention.

[0006] US 2011 / 0 285 654 A1 concerns an adaptive digital filtering method and a device for touch data in a touch system. The adaptive digital filtering includes estimating a signal-to-noise ratio (SNR) for stored touch data and decreasing the digital filter order when the SNR is high, as well as increasing the digital filter order when the SNR is low.

[0007] US patent 2016 / 0018921A1 describes the adjustment of stimulation signal amplitudes in capacitive touch sensor panels and / or styluses to reduce power consumption while maintaining satisfactory touch performance. To achieve this, one or more metrics can be measured, calculated, or otherwise determined to serve as predictors of touch performance, and these metrics can be processed to determine the minimum stimulation voltage required to maintain acceptable touch performance. Finally, German patent DE 112016005279T5 describes a

[0008] A delta modulator receiving channel for capacitance measurement circuits has one input configured to receive a first signal from a receiving electrode, wherein the first signal from the receiving electrode is a current induced at the receiving electrode by a drive signal on a drive electrode and a counter-capacitance between the receiving electrode and the drive electrode. The receiving channel further comprises a conversion circuit configured to convert the first signal into a second signal, wherein the receiving electrode is coupled to a first input of the conversion circuit and wherein a second input of the conversion circuit is coupled to a reference voltage.A quantizer circuit of the receive channel is configured to convert the second signal into a bitstream, and a filter circuit of the receive channel is coupled to the quantizer circuit and configured to provide a filtered output of the bitstream from the quantizer circuit. A current source of the receive channel is coupled between the output of the filter circuit and the conversion circuit, and the current source is configured to provide a feedback current to an input of the conversion circuit. A demodulation circuit of the receive channel is coupled to the output of the filter circuit, and the demodulation circuit is configured to generate a static output of the receive channel. BRIEF DESCRIPTION OF THE FIGURES

[0009] The embodiments shown are illustrated in the figures of the accompanying drawings as examples and are not exhaustive. Fig. Figure 1 is a block diagram illustrating a stacked structure of a touch field according to aspects of the revelation. Fig. Figure 2 is a block diagram illustrating, according to aspects of the revelation, a system for suppressing noise from a touch field. Fig. Figure 3 is a block diagram illustrating a system for suppressing noise from a touch field according to aspects of the disclosure and includes a circuit model of the touch field stack setup. Fig. Figure 4 is a block diagram illustrating, according to aspects of the revelation, a system for suppressing noise from a touch field with an alternative circuit implementation. Fig. Figure 5 is a block diagram illustrating, according to aspects of the revelation, a system for suppressing noise from a touch field that includes a filter. Fig. Figure 6 is a block diagram illustrating, according to aspects of the disclosure, the path of the noise signal in a system for suppressing noise from a touch field. Fig. Figure 7 is a block diagram illustrating, according to aspects of the revelation, a system for suppressing noise from a touch field using a filter in an alternative circuit implementation. Fig. Figure 8 is a block diagram illustrating, according to aspects of the revelation, a system for suppressing noise from a touch field with an alternative hardware circuit implementation. Fig. Figure 9 is a block diagram illustrating, according to aspects of the revelation, a system for suppressing noise from a touch field with another alternative circuit implementation. Fig. Figure 10 is a block diagram illustrating, according to aspects of the disclosure, a system for suppressing noise from a touch field with an alternative circuit implementation. Fig. Figure 11 is a flowchart illustrating a method for suppressing a noise signal from a touch field, according to aspects of the disclosure. Fig. Figure 12 is a flowchart illustrating, according to aspects of the disclosure, a procedure for determining a damping coefficient used to generate the estimated noise signal. Fig. Figure 13 is a block diagram illustrating, according to aspects of the disclosure, an electronic system that processes touch data. Fig. Figure 14 illustrates an embodiment of a core architecture of the PSoC® (Programmable System On a Chip) processing device according to aspects of the disclosure. DETAILED DESCRIPTION

[0010] For the purpose of clarification, numerous specific details are presented in the following description to provide a thorough understanding of the present embodiments. However, it will be obvious to a person skilled in the art that the present embodiments can be implemented without these specific details. In other cases, well-known circuits, structures, and techniques are not shown in detail but rather in a block diagram to avoid unnecessarily obscuring the understanding of this description.

[0011] A reference in the description to "an embodiment" means that a specific feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. The phrase "in an embodiment" appearing at different points in this description does not necessarily refer to the same embodiment.

[0012] In some touch detection systems, such as capacitive touch detection systems, a noise source within a touch field can generate noise signals that interfere with the detection of a touch object near the touch field. For example, an electrode layer (also referred to herein as the "detection arrangement") may be positioned over a display device, such as a liquid crystal display of a touch field. A noise signal from the operation of the display device may be coupled into the electrode layer via parasitic capacitive coupling. The coupled noise signal can interfere with the measurement signal (e.g., a transmit (Tx) signal) at the electrode layer, which is used to detect a touch object near the electrode layer.

[0013] In some touch detection systems, a shielding layer is placed between the electrode layer and the display device to help shield the electrode layer from the noise signal generated by the display device. The shielding layer may be coupled to a ground potential. However, the shielding layer has a surface resistance that, in the presence of the noise signal, creates a voltage potential. Thus, the noise signal is coupled to the electrode layer via parasitic capacitive coupling between the electrode layer and the shielding layer, obscuring the measurement signal used to detect a touch object.

[0014] Some touch detection systems can use a first electrode of the electrode layer to capture the noise signal. After capturing the noise signal, a second, different electrode (or the same electrode) can be used to subsequently measure a touch using a measurement signal. The captured noise signal from the first electrode can be used to reduce the noise in the measurement signal taken at the second electrode. However, such systems may suffer from a degradation in linearity and accuracy. These systems can be highly sensitive to touch from a contact object. For systems that are highly sensitive to touch, the capture and measurement process can be performed sequentially.If, for example, the system described above simultaneously measures the noise signal at the first electrode and the measurement signal at the second electrode, the first electrode acquires a large amount of the measurement signal and the associated touch data. If the signal from the first electrode, which contains a large amount of the measurement signal, is used to reduce the noise of the measurement signal from the second electrode, a large proportion of the usable data (e.g., touch data) is eliminated from the measurement signal, leading to inaccurate touch measurements.

[0015] Aspects of the disclosure address the aforementioned and other challenges by measuring a first signal, indicating a contact object near an electrode layer, on a first channel of a processing device. A channel can denote hardware, firmware, software, or a combination thereof, used to receive, manipulate, or measure a received signal. The first channel is coupled to the electrode layer. The first signal comprises a contact data component and a first noise component generated by a noise source. The second channel of the processing device measures a second signal, which includes a second noise component generated by the noise source. The second channel is coupled to a shielding layer located between the noise source and the electrode layer.Using the second noise component of the second signal associated with the second channel, an estimated noise signal is generated. This estimated noise signal is an estimate of the first noise component of the first signal. The estimated noise signal is subtracted from the measured first signal to obtain the touch data component of the first signal. In one embodiment, the measurement of the first signal on the first channel is performed simultaneously with the measurement of the second signal.

[0016] The noise signal picked up at the shielding layer comprises a negligible amount of the measurement signal because the shielding layer is further away from the contact object and is partially shielded by the upper electrode layer. The measurement signal introduced from the electrode layer into the shielding layer can be significantly attenuated (e.g., by an order of magnitude). This reduces the amount of the measurement signal (and the contact data component within it) that couples with the shielding layer and is picked up at the second channel. The signal received from the shielding layer can be used to reduce the noise in the measurement signal without significantly affecting the usable contact data of the measurement signal.

[0017] Aspects of the disclosure can be applied to self-capacitance measurement techniques or counter-capacitance measurement techniques.

[0018] Fig. Figure 1 is a block diagram illustrating a stacked structure of a touch field according to aspects of the disclosure. A system 100 shows a touch field stacked structure 101 illustrating different layers enclosed within a touch field. A touch field can display images and videos to users and may be included in various electronic devices, such as mobile devices or front-panel displays. A touch field can also be used in conjunction with a processing device 116 to detect a touch (also referred to as a "touch event") by a touch object 102 (e.g., a human finger or other touch object) near the touch field. For example, a touch by the touch object 102 in physical contact with a surface can be detected.In another example, contact by a contact object at some distance above a support 104 (e.g., hovering 35 millimeters (mm) above the support 104) can also be detected. It should be noted that, using aspects of the present disclosure, a contact object near the contact area can be detected at distances greater than 35 mm.

[0019] In one embodiment, the touch field stack assembly 101 can comprise one or more layers: a support 104, an electrode layer 106, a shielding layer 108, or a noise source 112. As illustrated, each of the layers mentioned above can be arranged above the layer(s) mentioned below. For example, the support 104 is arranged above the electrode layer 106, the shielding layer 108, and the noise source 112. In another example, the shielding layer 108 can be arranged between the electrode layer 106 and the noise source 112.

[0020] In one embodiment, the layer 104 can be a transparent or semi-transparent material arranged over the electrode layer 106. The layer 104 can provide protection or other functionality, such as filtering, for the underlying layers.

[0021] In one embodiment, the electrode layer 106 (also referred to herein as the "sensing arrangement") comprises one or more electrodes. In one embodiment, the electrode layer 106 can be a capacitive sensing arrangement. For illustrative purposes, and not as a limitation, the touch field stack assembly 101 is illustrated with a single electrode (i.e., a receive (Rx) electrode). It can be recognized that the electrode layer 106 can comprise many electrodes, such as multiple transmit (Tx) electrodes and multiple Rx electrodes. The electrode layer 106 can be used to sense the touch object 102 near the electrode layer 106. For example, in counter-capacitance mode, a Tx signal can be generated and coupled to a Tx electrode. From the Tx electrode, the Tx signal can be capacitively coupled to a respective Rx electrode.In the presence of a contact object 102, a change in capacitance between the Tx electrode and the respective Rx electrode is measured at the Rx electrode of the electrode layer 106 (e.g., the measurement signal). The measurement signal can include a contact data component indicating a contact object 102 near the Rx electrode of the electrode layer 106. In counter-capacitance mode, the measurement signal can be an induced current at the Rx electrode caused by the Tx signal from the respective Tx electrode. In another example, in self-capacitance mode, an Rx electrode can be excited using an excitation signal (e.g., by varying the ground potential). A contact object near the Rx electrode can cause capacitive coupling with the respective Rx electrode and change the capacitance detected at the Rx electrode. A change in capacitance at the Rx electrode (e.g.,The change (from the absence of a contact object near the Rx electrode to the presence of a contact object near the Rx electrode) can be measured using the measurement signal. The measurement signal can include a contact data component indicating the presence of a contact object 102 near the Rx electrode of the electrode layer. In self-capacitance mode, the measurement signal can be an induced signal at the Rx electrode caused by the excitation signal.

[0022] In embodiments, the electrode layer 106 can be a transparent or semi-transparent conductive material such as indium tin oxide (ITO). The electrode layer 106 (i.e., the sensing arrangement) and the touch detection are described with reference to Fig. 11 further described.

[0023] In one embodiment, the shielding layer 108 can be used to help shield the electrode layer 106 from parasitic noise signals. For example, noise from the noise source 112 can be introduced into the electrode layer 106 via parasitic capacitive coupling. The noise introduced into the electrode layer 106 by the noise source 112 can combine with a measurement signal that includes touch data and reduce the accuracy of the touch detection. A shielding layer 108 can be used to help decouple one or more noise sources, such as the noise source 112, from the electrode layer 106 and increase the accuracy of a measurement signal. In the present example, the shielding layer 108 is coupled to a system ground 114, which can denote the ground potential of the device in which the touch field stack assembly 101 is implemented.For example, in a mobile device, the system ground 114 can be a battery of the mobile device. In embodiments, the shielding layer 108 can be a transparent or semi-transparent conductive material. The material of the shielding layer can be similar to the material described with reference to the electrode layer 106. For example, the shielding layer can comprise indium tin oxide (ITO). In one embodiment, the shielding layer 108 is a continuous, flat, and conductive material.

[0024] In one embodiment, the noise source 112 is arranged beneath the shielding layer 108. In another embodiment, the noise source 112 can generate a noise signal, as illustrated by the noise signal 126. The noise signal 126 generated by the noise source 112 can be introduced into the shielding layer 108 and the electrode layer 106 via parasitic coupling. For example, a first noise component of the noise signal 126 can be introduced into the electrode layer 106 (e.g., the Rx electrode), and a second noise component of the noise signal 126 can be introduced into the shielding layer 108. The noise signal 126 can comprise both the first and second noise components. The first and second noise components can be proportional to each other.The property of proportionality of the first and second noise components of the noise signal 126 can be used to help cancel out the first noise component received at the Rx electrode, as illustrated below and in aspects of the revelation.

[0025] In one embodiment, a measurement signal is measured through an Rx channel, such as channel 124A. The introduced noise signal 126 can become part of the measurement signal, e.g., a noise component of the measurement signal. The measurement signal can also include a touch data component (e.g., a voltage or current indicating a change in capacitance) that can be obscured by the noise signal, potentially leading to reduced touch detection accuracy.

[0026] In some embodiments, the noise source 112 may comprise a display device, such as a liquid crystal display (LCD). In other embodiments, the display device may be a different type of display, such as an organic light-emitting diode (OLED) or another type of display device.

[0027] In one embodiment, the electrode layer 106 is coupled to the processing device 116. The processing device 116 can measure signal changes, such as capacitance changes, of the electrode layer 106 and produce digital outputs (hereinafter also referred to as "counts" or "digital counts") that indicate a touch near a touch field. In one embodiment, each Rx electrode can be coupled to a separate channel 124A-124N of the processing device 116. It should be noted that in other embodiments, a channel can be coupled to more than one Rx electrode at a single time. In still other embodiments, a channel can be coupled to multiple Rx electrodes, but only to one Rx electrode at a time (e.g., via a multiplexer).

[0028] In one embodiment, a channel, such as channel 124A, can comprise hardware or firmware to measure a signal, such as a measurement signal, received from the respective Rx electrode of electrode layer 106. For example, the measurement signal can be received by a buffer 118. The buffer can buffer or amplify the received measurement signal. In one embodiment, the buffer 118 can be a buffer with a gain factor of one. In other embodiments, the buffer 118 can have a certain amount of gain. In one embodiment, the positive terminal of the buffer 118 can be connected to the output of the buffer 118. The negative terminal of the buffer 118 can be coupled to a reference voltage. In other embodiments, a buffer with different configurations can be implemented.

[0029] In one embodiment, the buffered measurement signal at the output of buffer 118 can be integrated by an integrator 120. The integrator 120 can integrate the buffered measurement signal to combine it and produce a raw measurement signal. In one embodiment, the integrated measurement signal is an analog voltage or an analog current. In another embodiment, the measurement signal can include a current (e.g., a charge) being integrated into a capacitor (e.g., accumulating the charge). The integrated current can be detected as a voltage change. In other embodiments, the integrator 120 can be a hardware circuit, firmware, or a combination thereof. In some embodiments, a specific channel 124A-124N can have the same, different, more or fewer components in a different or the same configuration as in Fig. 1 illustrated. It should be noted that the components illustrated with reference to channel 124A are provided for illustrative purposes and not as a limitation.

[0030] Fig. Figure 2 is a block diagram illustrating, according to aspects of the revelation, a System 200 for suppressing noise from a touch field. Components from Fig. 1 are used to help identify aspects from Fig. 2 to describe. Fig. Figure 2 shows the touch field stack setup 101, as it is in Fig. Figure 1 illustrates this. A channel 224A and the components within it can be connected to channel 124A from Fig. 1. Buffer 218A and 218B can be used to replace buffer 118. Fig. 1. Integrators 220A and 220B can be similar to integrator 120. Fig. 1. be similar.

[0031] As in Fig. As shown in Figure 2, the Rx electrode of electrode layer 106 is coupled to channel 224A, and the shielding layer 108 is coupled to channel 224B. Both channels 224A and 224B are part of the processing device 116. In one embodiment, channel 224A and channel 224B (hereinafter referred to generally as "channel / channels 224") are physically separate channels (e.g., coupled to two individual output pins of the processing device 116). Each channel 224 can comprise its own hardware. In another embodiment, different channels can be coupled to a single pin of the processing device 116 at different times, for example, using a switch or multiplexer. For example, the shielding layer 108 can be coupled to channel 224B at times when reducing touch field noise in the measurement signal is deemed important.At other times, channel 224B can be coupled to an Rx electrode of electrode layer 106 to measure a respective measurement signal.

[0032] The output of the integrator 220B of channel 224B is coupled to the input of an attenuator 230. The output of the attenuator 230 is coupled to a subtraction module 228, which is capable of subtracting one signal from another. In embodiments, the attenuator 230 may comprise an attenuator circuit, firmware, or a combination thereof. In embodiments, the subtraction module 228 may comprise circuits, firmware, or a combination thereof. In one embodiment, the attenuator 230 or the subtraction module 228 is part of a channel 224A or 224B. In other embodiments, the attenuator 230 or the subtraction module 228 may be located outside of channels 224.

[0033] The noise signal 126 is coupled to both the shielding layer 108 and the Rx electrode of the electrode layer 106. The coupled noise signal 126 is illustrated as having a first noise component 232A, which is coupled to the Rx electrode of the electrode layer 106, and a second noise component 232B, which is coupled to the shielding layer 108. The first noise component 232A is coupled to channel 224A, and the second noise component 232B is coupled to 224B.

[0034] In one embodiment, a measurement signal 234 is received on channel 224A. The measurement signal 234 can indicate contact by a contact object 102 near the electrode layer 106. The measurement signal 234 can include a contact data component, indicating contact near the electrode layer 106, and a first noise component 232A. For example, in a counter-capacitance implementation, a Tx transmission signal can be transmitted to a Tx electrode. The presence of the contact object 102 changes the capacitance between the Tx electrode and the respective Rx electrode of the electrode layer 106. Information about the change in capacitance is included in the contact data component of the measurement signal 234. The noise component 232A introduced by the noise source 112 is also coupled to the Rx electrode of the electrode layer 106 and included in the measurement signal 234.

[0035] In one embodiment, a shielding signal 236 is received on channel 224B. The shielding signal 236 can include the second noise component 232B.

[0036] In one embodiment, the measurement signal 234 is measured at channel 224A of the processing device 116. In another embodiment, the measurement may include buffering the measurement signal 234 in buffer 218A and integrating the buffered measurement signal in integrator 220A, as described with reference to Fig. 1 described in more detail.

[0037] In one embodiment, the shielding signal 236, which includes the second noise component 232B, is measured at channel 224B of the processing device 116. In another embodiment, the measurement may include buffering the shielding signal 236 in buffer 218B and integrating the buffered shielding signal in integrator 220B.

[0038] In one embodiment, the processing device 116 can generate an estimated noise signal using the second noise component 232B of the shielding signal 236. The estimated noise signal can be an estimate of the first noise component 232A of the measurement signal 234 received on channel 224A. In one embodiment, generating the estimated noise signal using the second noise component 232B of the shielding signal 236 involves multiplying the shielding signal 236 (e.g., the integrated shielding signal) by an attenuation coefficient (K) at an attenuator 230. It should be noted that an attenuation coefficient can be any real number. Attenuation can include reducing a signal, amplifying a signal, or buffering a signal (e.g., attenuation coefficient of 1).

[0039] In one embodiment, the estimated noise signal can be subtracted from the measurement signal 234 (e.g. the integrated measurement signal) by the subtraction module 228.

[0040] For example, the second noise component 232B can be proportional to the first noise component 232A of the noise signal 126. As such, the shielding signal 236 (e.g., the integrated shielding signal), which includes the second noise component 232B, can be attenuated (or amplified) by an attenuation coefficient (K) to produce an estimated noise signal. The estimated noise signal can be attenuated such that its magnitude is similar to the first noise component 232A of the measurement signal 234 received at channel 224A. The estimated noise signal can be subtracted from the measurement signal 234 to remove or reduce the first noise component 232A of the measurement signal 234. The remaining touch data component of the measurement signal 234 can be used to detect a touch near the electrode layer 106.The above operations can be performed when a contact object is present near the contact area or when no contact object is present.

[0041] Fig. Figure 3 is a block diagram illustrating, according to aspects of the disclosure, a System 300 for suppressing noise from a touch field and includes a circuit model of the touch field stack setup. Components from Fig. 1 and Fig. 2 are used to help identify aspects from Fig. 3 to describe. Fig. Figure 3 illustrates a circuit model of the touch field stack setup 101. The Rx electrode of the electrode layer 106 is connected by several resistors (R rx ) shown, which are coupled in series with channel 224A of the processing device 116. The shielding layer 108 is protected by several resistors (R s) shown, which are coupled in series with channel 224B of the processing device 116. Coupling capacitors 336 (C s2n ) represent the parasitic capacitive coupling between the shielding layer 108 and the noise source 112. Coupling capacitors 334 (C rx2s ) represent the parasitic capacitive coupling between the Rx electrode of the electrode layer 106 and the shielding layer 108.

[0042] Fig. Figure 4 is a block diagram illustrating, according to aspects of the disclosure, a System 400 for suppressing noise from a touch field with an alternative circuit implementation. Components from Fig. 1 and Fig. 2 are used to help identify aspects from Fig. 4 to describe. Integrators 420A and 420B can be added to the integrator 120 from Fig. 1. be similar.

[0043] Channel 424A and channel 424B can each contain integrator 420A and integrator 420B, respectively. Integrators 420A and 420B can be connected to integrator 120. Fig. 1. Channel 424A and channel 424B (hereinafter referred to generally as "channel(s) 424") can each include an analog-to-digital converter (ADC) 438A and 438B, respectively (hereinafter referred to generally as "ADC(s) 438"). The ADC 438 can convert an analog signal into an equivalent digital signal. For example, the measurement signal 234 on channel 224A can be integrated by the integrator 420A. The integrated measurement signal 234 can be converted from an analog signal into a digital signal by the ADC 438A. Similarly, the shielding signal 236 on channel 224B can be integrated by the integrator 420A. The integrated shielding signal 236 can be converted from an analog signal into a digital signal by the ADC 438B.

[0044] System 400 can provide similar noise reduction to that described with reference to the preceding figures. In one embodiment, the digital shield signal 236 can be attenuated by the attenuator 230. The attenuated digital shield signal 236 can be subtracted from the digital measurement signal 234 using the subtraction module 228. In one embodiment, the attenuator 230 or the subtraction module 228 is part of channel 424A or 424B. In other embodiments, the attenuator 230 or the subtraction module 228 can be located outside of channels 424.

[0045] Fig. Figure 5 is a block diagram illustrating, according to aspects of the revelation, a System 500 for suppressing noise from a touch field that includes a filter. Components from the Fig. 1-4 are used to help identify aspects of Fig. 5 to describe. It should be noted that unmarked components may be similar to their marked counterparts from previous figures.

[0046] In one embodiment, the system 500 can implement a filter 540 between the shielding layer 108 and the input of the buffer 218B. The filter 540 can be used to create a transfer function between the first noise component 232A of the measurement signal 234 and the second noise component 232B of the shielding signal 236 similar to that described in relation to Fig. 6 described in more detail.

[0047] In one embodiment, the filter 540 can include a capacitor 541 (C f ) comprising a component coupled in series with channel 224B and shielding layer 108. In one embodiment, the filter 540 may include a resistor 542 (R fThe resistor 542 may comprise a first terminal coupled between the shielding layer 108 and the channel 224B. The resistor 542 may comprise a second terminal coupled to a ground potential, such as the system ground 114. In one embodiment, the filter 540 comprises both the capacitor 541 and the resistor 542. In one embodiment, one or more of the capacitor 541 and the resistor 542 are implemented as discrete components outside the processing device 116. In another embodiment, one or more of the capacitor 541 and the resistor 542 are integrated as on-chip components of the processing device 116.

[0048] In one embodiment, a resistor of 554A (R) can be used. i ) between the Rx electrode of electrode layer 106 and the buffer 218A. In one embodiment, a resistor 554B (R) can be used. i) between the shielding layer 108 and the input of the buffer 218B. In embodiments, one or more resistors 544A and 544B (generally referred to as "resistor(s) 544") can be off-chip or on-chip components. The resistors 544 can provide support with respect to immunity, such as transient immunity or radio frequency immunity.

[0049] It should be noted that one or more channels may exhibit similar immunity resistances. For example, each channel may exhibit a similar immunity resistance coupled between the respective Rx electrode of electrode layer 106 and the respective channel of processing device 116.

[0050] Fig. Figure 6 is a block diagram illustrating, according to aspects of the disclosure, the path of the noise signal in a System 600 for suppressing noise from a touch field. Components from the Fig. 1-5 are used to help identify aspects of Fig. 6 to describe. It should be noted that unmarked components may be similar to their marked counterparts from previous figures.

[0051] In Fig. Figure 6 shows how the noise signal 126 from the noise source 112 propagates through the system 600. Signal waveforms 644A-644E (hereinafter referred to collectively as "signal waveform(s) 644") show the noise signal 126 or its noise components at different nodes (e.g., node AE) in the system 600. It should be noted that the signal waveforms are provided for illustrative purposes and not as a limitation. Different waveforms may be present in different applications.

[0052] At node A, the noise signal 126 is shown as a series of triangular waveforms, as illustrated by signal waveform 644A. The noise signal 126 propagates from node A to node B via a coupling capacitance 336 between the shielding layer 108 and the noise source 112.

[0053] From node A to node B, the noise signal 126 changes its shape (e.g., phase change), as illustrated by the signal waveform 644B. ​​The shape change can be caused by the coupling capacitance 336 between the shielding layer 108 and the noise source 112. From node B, the noise signal 126 propagates to both node C and node D.

[0054] From node B to node C, the noise signal 126 is slightly attenuated by the resistance value of the shielding layer 108, as shown by the signal waveform 644C.

[0055] From node B to node D, the noise signal 126 (e.g., the first noise component 232A of the noise signal 126) is coupled to the Rx electrode of the electrode layer 106 via a coupling capacitance 334 between the Rx electrode of the electrode layer 106 and the shielding layer 108. From node B to D, the noise signal 126 undergoes a further transition (e.g., phase change), as illustrated by the signal waveform 644D.

[0056] From node C to node E, the noise signal 126 at node E (e.g., the second noise component 232B of the noise signal 126) is shaped by the inclusion of capacitor 541 so that its shape is similar to that of the noise signal 126 at node D (as illustrated by signal waveforms 644E and 644D). The second noise component 232B of the noise signal 126, which has the shape of signal waveform 644E, can be attenuated by a specific attenuation coefficient at the attenuator 230 and can be subtracted from the first noise component 232A of the noise signal 126, which has the shape of signal waveform 644D.

[0057] Fig. Figure 7 is a block diagram illustrating, according to aspects of the disclosure, a System 700 for suppressing noise from a touch field with a filter in an alternative circuit implementation. Components from the Fig. 1-6 are used to help identify aspects of Fig. 7 to describe. It should be noted that unmarked components may be similar to their marked counterparts from previous figures. Components from Fig. 7 components can be made from Fig. 4. A filter 740 can be included and the filter 540 removed. Fig. 5 similar.

[0058] Fig. Figure 8 is a block diagram illustrating, according to aspects of the revelation, a System 700 for suppressing noise from a touch field with an alternative hardware circuit implementation. Components from the Fig. 1-7 are used to help identify aspects of Fig. 8 to describe. It should be noted that unmarked components may be similar to their marked counterparts from previous figures.

[0059] In one embodiment, a compensation circuit 850 can be used to minimize the noise introduced into a channel, such as channel 224A of the processing device 116. In one embodiment, the compensation circuit 850 can absorb the first noise component 232A at the input of the buffer 218A. The compensation circuit 850 can filter the first noise component 232A using a filter 840, invert the filtered first noise component 232A using an inverter 852, and introduce the inverted first noise component 232A into the shielding layer 108 using the inverter 852, which can reduce the noise component received at channel 224A.

[0060] In one embodiment, one or more components of the compensation circuit 850 are off-chip components located outside the processing device 116 (as illustrated). In another embodiment, one or more components of the compensation circuit 850 are on-chip components of the processing device 116. In one embodiment, the compensation circuit 850 comprises circuit hardware components. It should be noted that in some embodiments, the compensation circuit 850 may comprise the same, more, fewer, or different components configured in the same or a different configuration.

[0061] Fig. Figure 9 is a block diagram illustrating, according to aspects of the disclosure, a System 900 for suppressing noise from a touch field with another alternative circuit implementation. Components from the Fig. 1-8 are used to help identify aspects of Fig. 9 to describe. It should be noted that unmarked components may be similar to their marked counterparts from previous figures. The 900 system from Fig. 9 is from the System 400 and the System 700. Fig. 4 or Fig. 7 similar.

[0062] In one embodiment, the system implements a compensation circuit 950. The compensation circuit 950 performs similar operations to the compensation circuit 850. Fig. 8. In one embodiment, a compensation circuit 950 can be used to minimize the noise introduced into a channel, such as channel 224A of the processing device 116. In one embodiment, the compensation circuit 950 can absorb the first noise component 232A at the input of the buffer 218A. The compensation circuit 950 can filter the first noise component 232A using a filter 940 and invert the filtered first noise component 232A using an inverter 952, introducing the inverted first noise component 232A into the shielding layer 108, which can reduce the noise signal received at channel 224A.

[0063] In one embodiment, one or more components of the compensation circuit 950 are off-chip components located outside the processing device 116 (as illustrated). In another embodiment, one or more components of the compensation circuit 950 are on-chip components of the processing device 116. It should be noted that in some embodiments, the compensation circuit 950 may comprise the same, more, fewer, or different components configured in the same or a different configuration. In some embodiments, one or more components of the compensation circuit may be implemented in hardware, firmware, or a combination thereof.

[0064] Fig. Figure 10 is a block diagram illustrating, according to aspects of the disclosure, a System 1000 for suppressing noise from a touch field with an alternative circuit implementation. Components from the Fig. 1-9 are used to help identify aspects of Fig. 10 to describe. It should be noted that unmarked components may be similar to their marked counterparts from previous figures.

[0065] In the System 1000, noise reduction can be performed on a single channel, such as channel 224A. For example, the measurement signal 234, which has a first noise component 232A, can be supplied to a first input of the buffer 218A. The shielding signal 236 can be filtered by the filter 540 and attenuated by an attenuator 1030. The attenuated shielding signal 236 is supplied to a second input of the buffer 218A, which allows the buffer 218A to effectively filter the first noise component 232A (e.g., common-mode rejection) from the measurement signal 234. The buffered measurement signal 234 is then integrated at the integrator 220.

[0066] In one embodiment, the damping element 1030 is a hardware integrator and is integrated into channel 224A of the processing device.

[0067] Fig. Figure 11 is a flowchart illustrating, according to aspects of the disclosure, a method 1100 for suppressing a noise signal from a touch field. The method 1100 can be performed by processing logic comprising hardware (e.g., circuits, dedicated logic, programmable logic, microcode), software (e.g., instructions running on a processing device to perform a hardware simulation), or a combination thereof. In other implementations, a noise suppression module 1320 may consist of Fig. 13. Perform some or all of the operations. Components of the preceding figures can be used to help illustrate Procedure 1100. It should be noted that in some implementations, Procedure 1100 may include the same, different, a smaller, or a larger number of operations, performed in any order.

[0068] In block 1102, the processing logic measures a first signal (e.g., the measurement signal 234) on channel 224A of a processing device 116, indicating a contact object near an electrode layer 106. The first signal comprises a contact data component and a first noise component 232A generated by a noise source 112.

[0069] In one embodiment, measuring the first signal includes buffering the first signal using the buffer 218A of channel 224A and integrating the buffered first signal using an integrator 220A.

[0070] In another embodiment, measuring the first signal includes integrating the first signal using the integrator 420A and converting the first signal into a digital signal using the ADC 438A.

[0071] In block 1104, the processing logic measures a second signal (e.g., the shielding signal 236) on channel 224B of the processing device 116. This second signal includes a second noise component 232B generated by the noise source 112. Channel 224B is coupled to the shielding layer 108, which is located between the noise source 112 and the electrode layer 106.

[0072] In one embodiment, measuring the second signal includes buffering the second signal using the buffer 218B of channel 224B and integrating the buffered second signal using an integrator 220B.

[0073] In another embodiment, measuring the second signal includes integrating the second signal using the integrator 420B and converting the second signal into a digital signal using the ADC 438B.

[0074] In one embodiment, the measurement of the first signal on channel 224A is performed simultaneously with the measurement of the second signal on channel 224B.

[0075] In block 1106, the processing logic generates an estimated noise signal using the second noise component 232B of the second signal, which is associated with channel 224B. The estimated noise signal is an estimate of the first noise component 232A of the first signal.

[0076] In one embodiment, generating the estimated noise signal includes attenuating the second signal (e.g., the shielding signal 236) by an attenuation coefficient to generate the estimated noise signal. For example, after the second signal has been measured (e.g., buffered and integrated), it can be attenuated by the attenuator 230.

[0077] In block 1108, the processing logic can subtract the estimated noise signal from the measured first signal to obtain the touch data component of the first signal. For example, a subtraction module 228 can be used to subtract the estimated noise signal from the measured first signal. In one embodiment, the touch data can be used to determine whether a touch has occurred by a touch object 102 near an Rx electrode of the electrode layer 106.

[0078] As noted above, similar operations can be used for other channels associated with other Rx electrodes of electrode layer 106. In embodiments, channel 224A can be used to suppress noise for one or more channels associated with Rx electrodes.

[0079] Fig. Figure 12 is a flowchart illustrating, according to aspects of the disclosure, a method 1200 for determining an attenuation coefficient used to generate the estimated noise signal. The method 1200 can be performed by processing logic comprising hardware (e.g., circuits, dedicated logic, programmable logic, microcode), software (e.g., instructions running on a processing device to perform a hardware simulation), or a combination thereof. In other implementations, the noise reduction module 1320 may consist of Fig. 13. Perform some or all of the operations. Components of the preceding figures can be used to help illustrate Procedure 1200. It should be noted that in some implementations, Procedure 1200 may include the same, different, a smaller, or a larger number of operations, performed in any order.

[0080] In block 1202, the processing logic determines that the noise source 112 is switched on. For example, the processing device 116 can send a signal that switches on the display device. In another example, the processing device 116 has received a message that the display device is switched on, but cannot directly control the display device.

[0081] In block 1204, the processing logic can switch off one or more excitation voltages associated with the electrode layer 106. For example, during countercapacitance detection, the Tx excitation voltages can be removed. In another example, during selfcapacitance detection, the excitation voltage can be switched off by, for example, coupling the device ground of the processing device 116 to the system ground used by the noise source 112. In one embodiment, the excitation voltages are switched off so that a touch does not interfere with measurements of the noise signal 126 on either channel 224A or channel 224B of the processing device 116.

[0082] In block 1206, the processing logic sets the attenuation coefficient to a predefined number. For example, the attenuation coefficient of attenuator 230 can be set to 1, so that attenuator 230 buffers the second noise component (I2) 232B of noise source 112.

[0083] In block 1208, the processing logic on channel 224A of the processing device 116 measures the third signal, which comprises the third noise component (e.g., similar to the first noise component 232A). In one embodiment, measuring the third signal can be similar to measuring the first signal (e.g., the measurement signal 234) as described above, except that the third signal does not include a touch data component because the excitation signal is switched off.

[0084] In block 1208, the processing logic measures the fourth signal on channel 224B of the processing device 116. This signal comprises the fourth noise component (e.g., similar to the second noise component 232B). In one embodiment, the measurement of the fourth signal can be similar to the measurement of the second signal (e.g., the shielding signal 236), as described above.

[0085] In one embodiment, the third signal and the fourth signal are measured simultaneously.

[0086] In block 1210, the processing logic estimates the attenuation coefficient using the third and fourth signals from channel 224A and channel 224B, respectively. For example, the third signal represents the noise component (e.g., the first noise component 232A) of noise source 112 received by channel 224A. The fourth signal represents the noise component (e.g., the second noise component 232B) of noise source 112 received by channel 224B. Because the excitation signal is off, the signals received by channel 224A and channel 224B can be representative of noise source 112 without interference from signals representative of touch data.

[0087] In one embodiment, the attenuation coefficient can be estimated using a ratio of the third signal (e.g., the first noise component 232A) received on channel 224A to the fourth signal (e.g., the second noise component 232B) received on channel 224B. In another embodiment, the attenuation coefficient can be estimated using a least-squares approach with respect to the third and fourth signals.

[0088] In one embodiment, the damping element, such as the damping element 230 or the damping element 1030, can be adjusted using the estimated damping coefficient.

[0089] In one embodiment, the damping coefficient can be determined once, for example, after the system (e.g., the mobile device) has been manufactured. In another embodiment, the damping coefficient can be determined more than once, for example, periodically based on time, the number of on / off cycles of the system, or other criteria. In one embodiment, the damping coefficient can be determined dynamically, for example, when a user operates the system.

[0090] In another embodiment, the attenuation coefficient can be determined based on a temperature value detected in the system. In one embodiment, the processing logic determines that a temperature value meets a temperature threshold. In response to the determination that a temperature value meets a temperature threshold, the processing logic determines the attenuation coefficient used to generate the estimated noise signal. For example, the processing device 116 can receive or generate a temperature value indicating the temperature of the electrode layer 106 or the shielding layer 108. The temperature value may exceed one predefined threshold or fall below another predefined threshold, and in response, the processing device 116 executes the method 1200 to determine a new attenuation coefficient.

[0091] Fig. Figure 13 is a block diagram illustrating, according to aspects of the disclosure, an electronic system that processes touch data. Fig. Figure 13 illustrates an electronic system 1300 comprising a processing device 1310 (which may be similar to the processing device 116 described herein) that may be configured to measure capacitances from a sensing arrangement 1321 (e.g., a capacitive sensing arrangement) using the noise reduction module 1320, wherein the sensing arrangement 1321 forms a touch sensing surface 1316. In one embodiment, a multiplexer circuit may be used to connect a capacitance sensing circuit 1301 to a sensing arrangement 1321. The touch sensing surface 1316 (e.g., a touchscreen or touchpad) is coupled to the processing device 1310, which is coupled to a host 1350. In one embodiment, the touch sensing surface 1316 is a two-dimensional sensing arrangement (e.g., a 3-dimensional surface).the detection arrangement 1321), which uses the processing device 1310 to detect touches on the touch detection surface 1316.

[0092] In one embodiment, the sensing arrangement 1321 comprises electrodes 1322(1)-1322(N) (where N is a positive integer) arranged as a two-dimensional matrix (also known as an XY matrix). The sensing arrangement 1321 is coupled to pins 1313(1)-1313(N) of the processing device 1310 via one or more analog buses 1315 carrying multiple signals. In the sensing arrangement 1321, the first three electrodes (i.e., electrodes 1322(1)-(3)) are connected to the capacitance sensing circuit 1301 and to ground, thus illustrating a self-capacitance configuration. For the last electrode (i.e., 1322(N)), both terminals are connected to the capacitance sensing circuit 1301, thus illustrating a counter-capacitance configuration. It should be noted that both terminals of the other electrodes 1322 can also be connected to the capacitance detection circuit 1301.In an alternative embodiment without an analog bus, each pin can instead be connected either to a circuit that generates a transceiver (TX) signal or to an individual receive (RX) sensor circuit. The sensing arrangement 1321 can comprise a multidimensional capacitive sensing arrangement. The multidimensional sensing arrangement comprises multiple sensing elements organized as rows and columns. In another embodiment, the sensing arrangement 1321 operates as an APA countercapacitance sensing arrangement (APA = All Points Addressable). The sensing arrangement 1321 can be configured to have a flat surface profile. Alternatively, the sensing arrangement 1321 can have surface profiles that are not flat. Alternatively, other configurations of capacitive sensing arrangements can be used.For example, the sensing arrangement 1321 may have a hexagonal configuration or the like instead of vertical columns and horizontal rows. In one embodiment, the sensing arrangement 1321 may be enclosed in an indium tin oxide (ITO) field or a touchscreen field. In one embodiment, the sensing arrangement 1321 is a capacitive sensing arrangement. In another embodiment, the sensing arrangement 1321 is a non-transparent, capacitive sensing arrangement (e.g., a PC touchpad). In one embodiment, the sensing arrangement is configured such that the processing device 1310 can generate touch data for a touch detected near the capacitive sensing arrangement, with the touch data being represented as a plurality of cells.

[0093] In one embodiment, the capacitance sensing circuit 1301 may include a CDC or other means to convert a capacitance into a measured value. The capacitance sensing circuit 1301 may also include a counter or a timer for measuring the oscillator output. The processing device 1310 may further include software components to convert the counted value (e.g., the capacitance value) into a touch detection decision or a relative quantity. It should be noted that there are various known methods for measuring capacitance, such as current-versus-voltage phase-shift measurement, resistor-capacitor charge-time control, capacitive bridge divider, charge transfer, successive approach, sigma-delta modulators, charge accumulation circuits, field effect, counter-capacitance, frequency shift, or other capacitance measurement algorithms.It should be noted, however, that instead of evaluating the raw counts relative to a threshold, the Capacitance Detection Circuit 1301 can evaluate other measurements to determine user interaction. For example, in the Capacitance Detection Circuit 1301 which incorporates a sigma-delta modulator, the circuit evaluates the ratio of the output pulse widths (i.e., density domain) rather than evaluating whether the raw counts are above or below a certain threshold.

[0094] In another embodiment, the capacitance sensing circuit 1301 comprises a TX signal generator to generate a TX signal (e.g., a stimulus signal) to be applied to the TX electrode, and a receiver (also referred to as a "sensing channel" or "receive (Rx) channel" or "channel"), such as a buffer or an integrator, to measure an RX signal at the RX electrode. In some embodiments, each Rx channel may be coupled to a physical pin of the processing device 1310 (or the capacitance sensing circuit 1301). In some embodiments, each Rx channel may include hardware, such as a buffer or an integrator. In a further embodiment, the capacitance sensing circuit 1301 includes an analog-to-digital converter (ADC) coupled to an output of the receiver to convert the measured RX signal into a digital value.The digital value can be further processed by the processing device 1310, the host 1350, or both.

[0095] The processing device 1310 is configured to detect one or more touches on a touch sensing device, such as the sensing arrangement 1321. The processing device can detect conductive objects, such as touch objects (fingers or passive pins, an active pin, or a combination thereof). The capacitive sensing circuit 1301 can measure a touch data element on the sensing arrangement 1321. The touch data can be represented as multiple cells, with each cell representing an intersection of sensing elements (e.g., electrodes) of the sensing arrangement 1321. The capacitive sensing elements are electrodes made of conductive material, such as copper, silver, indium tin oxide (ITO), metal mesh, carbon nanotubes, or the like. The sensing elements can also be part of an ITO field.The capacitive sensing elements can be used to enable the capacitance sensing circuit 1301 to measure self-capacitance, counter-capacitance, or any combination thereof. In another embodiment, the touch data measured by the capacitance sensing circuit 1301 can be processed by the processing device 1310 to generate a capacitive 2D image of the sensing arrangement 1321 (e.g., a capacitive sensing arrangement). In one embodiment, when the capacitance sensing circuit 1301 measures the counter-capacitance of the touch sensing device (e.g., a capacitive sensing arrangement), the capacitance sensing circuit 1301 determines a capacitive 2D image of the touch sensing object on the touch surface and processes the data with respect to peak and position information.In another embodiment, the processing device 1310 is a microcontroller that receives a capacitive touch signal data set, for example from a sensing arrangement, and finger detection firmware running on the microcontroller identifies data set regions indicating touches, detects and processes peaks, calculates the coordinates, or any combination thereof. The firmware can calculate an exact coordinate for the resulting peaks. In one embodiment, the firmware can calculate the exact coordinates for the resulting peaks using a center point algorithm that calculates a center point of the touch, where the center point is a center of mass of the touch. The center point can be an X / Y coordinate of the touch. Alternatively, other coordinate interpolation algorithms can be used to determine the coordinates of the resulting peaks.The microcontroller can report the exact coordinates and other information to a host processor.

[0096] In one embodiment, the processing device 1310 further comprises a processing logic 1302. Some or all of the operations of the processing logic 1302 can be implemented in firmware, hardware, software, or a combination thereof. The processing logic 1302 can receive signals from the capacitance sensing circuit 1301 and determine the state of the sensing arrangement 1321, such as whether an object (e.g., a finger) is detected on or near the sensing arrangement 1321 (e.g., determine the presence of the object), determine where the object is located on the sensing arrangement (e.g., determine the object's location), track the object's movement, or track other information relating to an object detected by the touch sensor. In another embodiment, the processing logic 1302 can comprise the capacitance sensing circuit 1301.

[0097] The processing logic 1302 can be implemented in a capacitive touchscreen controller. In one embodiment, the capacitive touchscreen controller is one of the TrueTouch® capacitive controllers and the CapSense® technology controllers (touchscreens, buttons, sliders, proximity, etc.), such as the CY8C[2|3|4|5|6]xxxx family and the CY8CMBRxx family of CapSense controllers developed by Cypress Semiconductor Corporation, San Jose, California. The CapSense® technology can be provided as a peripheral function in the PSoC® (Programmable System On a Chip) processing device developed by Cypress Semiconductor Corporation, San Jose, California, such as the PSoC® 1, 3, 4, 5, and 6 devices.The CapSense® controller's sensing technology can detect touch locations of multiple fingers and a stylus on touchscreens, supports operating systems, and is optimized for low-energy multi-touch gesture and all-point touchscreen functionality. Alternatively, the touch position calculation features can be implemented in other touchscreen controllers or other touch controllers of touch sensing devices. In one embodiment, the touch position calculation features can be implemented with other touch filtering algorithms, as would be recognized by an average person skilled in the art who benefits from this disclosure.

[0098] In another embodiment, instead of performing the operations of the processing logic 1302 within the processing device 1310, the processing device 1310 can send the raw data or the partially processed data to the host 1350. The host 1350 can, as described in Fig. Figure 13 illustrates a decision logic 1351 that performs some or all of the operations of the processing logic 1302. The noise reduction module 1320 can be partially or completely implemented by the decision logic 1351. The noise reduction module 1320 can be a module within the decision logic 1351. Alternatively, the noise reduction module 1320 can be an algorithm within the decision logic 1351. The host 1350 can receive raw capacity data from the processing device 1310 and determine whether or not a touch has occurred on the sensing arrangement 1321. Operations of the decision logic 1351 can be implemented in firmware, hardware, software, or a combination thereof.The host 1350 can include a high-level application programming interface (API) in applications 1352 that perform routines on the received data, such as compensating for sensitivity differences, other compensation algorithms, baseline update routines, start and / or initialization routines, interpolation operations, or scaling operations. The operations described with respect to the processing logic 1302 can be implemented in the decision logic 1351, the applications 1352, or in other hardware, software, and / or firmware located outside the processing device 1310. In some other embodiments, the processing device 1310 is the host 1350.

[0099] In another embodiment, the processing device 1310 can also include a block 1303 with non-capture actions. The block 1303 with non-capture actions can be used to process data and / or receive data from or transmit it to the host 1350. For example, additional components can be implemented to operate the processing device 1310 alongside the capture arrangement 1321 (e.g., keyboard, keypad, mouse, trackball, LEDs, displays, or other peripheral devices).

[0100] As illustrated, the capacitance sensing circuit 1301 can be integrated into the processing device 1310. The capacitance sensing circuit 1301 can include an analog I / O for coupling to an external component, such as a touch sensor pad (not shown), the sensing arrangement 1321, a touch sensor slider (not shown), touch sensor buttons (not shown), and / or other devices. The capacitance sensing circuit 1301 can be configured to measure capacitance using counter-capacitance sensing techniques, self-capacitance sensing techniques, charge coupling techniques, combinations thereof, or the like. In one embodiment, the capacitance sensing circuit 1301 operates using a charge accumulation circuit, a capacitance modulation circuit, or other capacitance sensing methods known to those skilled in the art.In one embodiment, the capacitance sensing circuit 1301 is one of the Cypress controllers. Alternatively, other capacitance sensing circuits may be used. The counter-capacitance sensing arrangements or touchscreens as described herein may comprise a transparent, conductive sensing arrangement positioned on, in, or beneath either a visual display itself (e.g., an LCD monitor) or a transparent substrate in front of the display. In one embodiment, the TX and RX electrodes are configured in rows and columns, respectively. It should be noted that the rows and columns of electrodes can be configured by the capacitance sensing circuit 1301 in any selected combination as either TX or RX electrodes.In one embodiment, the TX and RX electrodes of the sensing arrangement 1321 are configurable to operate in a first mode as TX and RX electrodes of a counter-capacitance sensing arrangement for detecting touch objects, and in a second mode as electrodes of a coupled charge receiver for detecting a pen on the same electrodes of the sensing arrangement. The pen, which generates a pen-TX signal when activated, is used to couple charge to the capacitive sensing arrangement, rather than measuring a counter-capacitance at an intersection of an RX electrode and a TX electrode (comprising one or more sensing elements), as is done in counter-capacitance sensing. An intersection between two sensing elements can be understood as a location where one sensing electrode crosses or overlaps another, while maintaining galvanic isolation between them.The capacitance associated with the intersection between a TX electrode and an RX electrode can be detected by selecting each available combination of TX and RX electrodes. When a contact object (i.e., a conductive object), such as a finger or a pen, approaches the detection arrangement 1321, the contact object causes a decrease in the return capacitance between some of the TX / RX electrodes. In another embodiment, the presence of a finger increases the coupling capacitance of the electrodes. Thus, the location of the finger on the detection arrangement 1321 can be determined by identifying the RX electrode that exhibits a reduced coupling capacitance between the RX electrode and the TX electrode to which the TX signal was applied at the time the reduced capacitance was measured at the RX electrode.Therefore, the locations of one or more inputs can be determined by sequentially determining the capacitances associated with the intersection of electrodes. It should be noted that the process can calibrate the sensing elements (intersections of RX and TX electrodes) by establishing baselines for the sensing elements. It should also be noted that interpolation can be used to detect a finger position with resolutions higher than the row / column spacing, as would be recognized by an average professional. Additionally, various types of coordinate interpolation algorithms can be used to detect the center of the touch, as would be recognized by an average professional.

[0101] It should also be noted that the embodiments described herein are not limited to having a configuration of a processing device coupled to a host, but may include a system that measures the capacity at the acquisition device and sends the raw data to a host computer where it is analyzed by an application. In another embodiment, the processing performed by the processing device 1310 takes place in the host.

[0102] The processing device 1310 can be located on a common substrate, such as a die substrate with an integrated circuit (IC) or a multi-chip module substrate. Alternatively, the components of the processing device 1310 can be one or more separate integrated circuits and / or discrete components. In one embodiment, the processing device 1310 can be the PSoC® (Programmable System On a Chip) processing device developed by Cypress Semiconductor Corporation, San Jose, California. One embodiment of the PSoC® processing device is described below with reference to Fig. Figure 14 illustrates and describes the processing device. Alternatively, the processing device 1310 can be one or more other processing devices known to those skilled in the art, such as a microprocessor or central processing unit, a controller, a special-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or another programmable device. In an alternative embodiment, the processing device 1310 can, for example, be a network processor comprising multiple processors, including a core unit and multiple micro-engines. Additionally, the processing device 1310 can comprise any combination of general-purpose processing device(s) and special-purpose processing device(s).

[0103] The capacitance sensing circuit 1301 can be integrated into the IC of the processing device 1310 or, alternatively, into a separate IC. Alternatively, descriptions of the capacitance sensing circuit 1301 can be generated and compiled for inclusion in other integrated circuits. For example, using a hardware description language such as VHDL or Verilog, behavior-level code describing the capacitance sensing circuit 1301, or portions thereof, can be generated and stored on a machine-accessible medium (e.g., CD-ROM, hard disk, floppy disk, etc.). Furthermore, the behavior-level code can be compiled into register-transfer-level code (RTL code), a netlist, or even a circuit layout and stored on a machine-accessible medium.The behavioral level code, the RTL code, the netlist, and the circuit layout can represent different levels of abstraction to describe the capacitance sensing circuit 1301.

[0104] It should be noted that the components of electronic system 1300 can include all the components described above. Alternatively, electronic system 1300 can include some of the components described above.

[0105] In one embodiment, the electronic system 1300 is used in a tablet computer. Alternatively, the electronic device can be used in other applications, such as, but not limited to, a notebook computer, a mobile phone, a personal data assistant (“PDA”), a keyboard, a television, a remote control, a monitor, a handheld multimedia device, a handheld (audio and / or video) player, a handheld gaming device, a signature input device for point-of-sale transactions, an eBook reader, a global positioning system (“GPS”), or a control panel.The embodiments described herein are not limited to touchscreens or touch sensor pads for notebook implementations; rather, they can be used in other capacitive sensing implementations. For example, the sensing device can be a touch sensor slider (not shown) or touch sensor buttons (e.g., capacitive sensing buttons). In one embodiment, these sensing devices include one or more capacitive sensors or other types of capacitive sensing circuitry. The operations described herein are not limited to notebook pointer operations; rather, they can include other operations such as lighting control (dimmer), volume control, control of graphic equalizers, speed control, or other control operations requiring gradual or discrete adjustments.It should also be noted that these embodiments of capacitive sensing implementations can be used in conjunction with non-capacitive sensing elements, including, but not limited to, selection buttons, sliders (e.g., display brightness and contrast), scroll wheels, multimedia controls (e.g., volume, track advance, etc.), handwriting recognition, and operation of a numeric keypad.

[0106] The electronic system 1300 comprises a capacitive button 1323. The capacitive button 1323 is connected to the processing device 1310. In one embodiment, the capacitive button 1323 can be a single electrode. In another embodiment, the capacitive button 1323 can be a pair of electrodes. In one embodiment, the capacitive button 1323 is arranged on a substrate. In one embodiment, the capacitive button 1323 can be part of the sensing arrangement 1321. In another embodiment, the capacitive button can be separate from the sensing arrangement 1321. In one embodiment, the capacitive button 1323 can be used in self-capacitance sensing mode. In another embodiment, the capacitive button 1323 can be used in counter-capacitance sensing mode. In one embodiment, the capacitive key 1323 can be used in both self-capacitance scanning mode and counter-capacitance scanning mode.Alternatively, the capacitive button 1323 is used in a multi-stage capacitance measurement process, as described herein. The capacitive button 1323 can be one or more individual buttons.

[0107] Fig.Figure 14 illustrates an embodiment of a core architecture 1400 of the PSoC® processing device, such as that used in the PSoC3® product family offered by Cypress Semiconductor Corporation (San Jose, California). In one embodiment, the core architecture 1400 comprises a microcontroller 1402. The microcontroller 1402 includes a CPU core 1404 (CPU = Central Processing Unit), a flash program memory 1406, a debug-on-chip (DOC) unit 1408, a prefetch buffer 1410, a private SRAM (Static Random Access Memory) 1412, and special function registers 1414. In one embodiment, the DOC unit 1408, the prefetch buffer 1410, the private SRAM 1412, and the special function registers 1414 are coupled to the CPU core 1404, while the flash program memory 1406 is coupled to the prefetch buffer 1410.

[0108] The core architecture 1400 can also include a CHub (C = Core) 1416, which comprises a bridge 1418 and a DMA controller (DMA = Direct Memory Access) 1420 and is coupled to the microcontroller 1402 via a bus 1422. The CHub 1416 can provide the primary data and control interface between the microcontroller 1402 with its peripherals (e.g., peripherals) and memory, and a programmable core 1424. The DMA controller 1420 can be programmed to transfer data between system elements without burdening the CPU core 1404. In various embodiments, each of these subcomponents of the microcontroller 1402 and the CHub 1416 can differ depending on the choice or type of CPU core 1404. The CHub 1416 can also be coupled with a shared SRAM 1426 and an SPC (System Performance Controller)1428.The private SRAM 1412 is independent of the shared SRAM 1426, which the microcontroller 1402 accesses via bridge 1418. The CPU core 1404 accesses the private SRAM 1412 without going through bridge 1418, thus allowing accesses to a local register and RAM to occur simultaneously with the DMA access to the shared SRAM 1426. Although labeled here as SRAM, these memory modules can, in various other embodiments, be any type from a wide range of (volatile or non-volatile) memory or data storage modules.

[0109] In various embodiments, the programmable core 1424 can comprise different combinations of subcomponents (not shown), including, but not limited to, a digital logic arrangement, digital peripherals, analog processing channels, analog peripherals for global routing, one or more DMA controllers, SRAM and other suitable data storage types, I / O ports and other suitable types of subcomponents.In one embodiment, the programmable core 1424 comprises a GPIO and EMIF block 1430 (GPIO = General Purpose Input / Output, EMIF = Extended Memory Interface) to provide a mechanism for extending the external off-chip access of the microcontroller 1402, a programmable digital block 1432, a programmable analog block 1434, and a special function block 1436, each configured to implement one or more of the subcomponent functions. In various embodiments, the special function block 1436 may include dedicated (non-programmable) function blocks and / or one or more interfaces to dedicated function blocks, such as USB, a crystal oscillator driver, JTAG, or the like.

[0110] The programmable digital block 1432 can include a digital logic assembly comprising an array of digital logic blocks and associated routing. In one embodiment, the digital block architecture includes UDBs (Universal Digital Blocks). For example, each UDB can include an ALU along with CPLD functionality.

[0111] In various embodiments, one or more UDBs of the programmable digital block 1432 can be configured to perform various digital functions, including, but not limited to, one or more of the following: a simple I2C slave; an I2C master; an SPI master or slave; a multi-wire (e.g., 3-wire) SPI master or slave (e.g., MISO / MOSI multiplexed on a single pin); timers and counters (e.g., a pair of 8-bit timers or counters, a 16-bit timer or counter, an 8-bit capture timer, or the like); PWMs (e.g., a pair of 8-bit PWMs, a 16-bit PWM, an 8-bit dead-zone PWM, or the like); a level-sensitive I / O interrupt generator; an incremental rotary encoder, a UART (e.g. half-duplex capable); delay lines; and any other suitable type of digital functions or combinations of digital functions that may be implemented in a variety of UDBs.

[0112] In other embodiments, additional functions may be implemented using a group of two or more UDBs. For illustrative purposes only, and not as a limitation, the following functions may be implemented using multiple UDBs: an I2C slave that supports hardware address detection and has the ability to support a complete transaction without intervention from the CPU core (e.g., CPU core 1404), thus helping to prevent the forced clock from extending to any bit in the data stream; an I2C multi-master that may include a slave option in a single block; a PRS or CRC of arbitrary length (up to 32 bits); SDIO; SGPIO; a digital correlator (e.g., up to 32 bits with 4x oversampling and supporting a configurable threshold); a LIN bus interface; a sigma-delta modulator (e.g.,for a Class D audio DAC featuring a differential output pair); a 12S (stereo); an LCD driver (e.g., UDBs can be used to implement timing control of the LCD driver blocks and provide display RAM addressing); a full-duplex UART (e.g., 7-, 8-, or 9-bit with 1 or 2 stop bits and parity, and RTS / CTS support); IRDA (transmit or receive); a capture timer (e.g., 16-bit or similar); dead-zone PWM (e.g., 16-bit or similar); an SM bus (including software formatting of SM bus packets with CRC); a brushless motor drive (e.g., to support 6 / 12-step commutation); automatic baud rate detection and generation (e.g.,automatic determination of the baud rate for standard rates from 1200 to 115200 baud and, after detection, generation of the required clock to generate the baud rate); and any other suitable type of digital functions or combinations of digital functions that may be implemented in a variety of UDBs.

[0113] The programmable analog block 1434 may include, but is not limited to, the following analog resources: comparators, mixers, PGAs (programmable gain amplifiers), TIAs (trans-impedance amplifiers), ADCs (analog-to-digital converters), DACs (digital-to-analog converters), voltage references, current sources, sample-and-hold circuits, and any other suitable type of analog resource.The programmable analog block 1434 can support various analog functions, including but not limited to: analog routing, I / O support for LCD drive, capacitance sensing, voltage measurement, motor control, current-to-voltage conversion, voltage-to-frequency conversion, differential gain, light measurement, inductive position monitoring, filtering, voice coil drive, magnetic card reading, acoustic Doppler measurement, echolocation, modem transmit and receive coding, or any other suitable type of analog function.

[0114] In one embodiment, the programmable core 1424 may include the noise reduction module 1320 to perform one or more aspects of the disclosure. Some or all of the components or operations of the noise reduction module 1320 may be performed by one or more of the subcomponents of the programmable core 1424. It should be noted that other components of the core architecture 1400 may perform some or all of the operations of the noise reduction module 1320 or may include some or all of the components used by the noise reduction module 1320.

[0115] The embodiments described herein can be used in various configurations of counter-capacitance detection systems, in self-capacitance detection systems, or combinations of both. In one embodiment, the capacitance detection system detects multiple detection elements activated in the arrangement and can analyze a signal pattern at the adjacent detection elements to separate noise from an actual signal. The embodiments described herein are not limited to a specific capacitive detection solution and can equally be used with other detection solutions, including optical detection solutions, as would be recognized by a person skilled in the art who benefits from this disclosure.

[0116] Numerous details are set forth in the description above. However, it will be obvious to an average person skilled in the art, benefiting from this disclosure, that embodiments of the present disclosure can be carried out without these specific details. In some cases, well-known structures and devices are shown in block diagram form rather than in detail to avoid obscuring the description.

[0117] Some sections of the detailed description are presented in the form of algorithms and symbolic representations of operations on data bits within computer memory. These algorithmic descriptions and representations are the means used by data processing professionals to most effectively communicate the substance of their work to other professionals. An algorithm is understood here, and generally, as a consistent sequence of steps that leads to a desired result. The steps are those that require physical manipulations of physical quantities. Usually, but not necessarily, these quantities take the form of electrical or magnetic signals that can be stored, transferred, combined, compared, and otherwise manipulated.It has sometimes proven practical, mainly for reasons of general use, to refer to these signals as bits, values, elements, symbols, characters, expressions, numbers, or the like.

[0118] It should be borne in mind, however, that all these and similar terms are related to the actual physical quantities and are merely practical labels given to them. Unless expressly specified otherwise, as can be seen from the discussion above, it is understood that throughout the description, discussions using terms such as "measure," "generate," "subtract," "buffer," "integrate," "multiply," "determine," "cause," "adjust," "estimate," or the like, refer to the actions and processes of a computer system or similar electronic computing device that processes data stored in the computer system's registers and memories as physical (e.g.,electronic) quantities are manipulated and transformed into other data that are represented in a similar manner as physical quantities within the computer system memory or registers or other such devices for storing, transmitting or displaying information.

[0119] The words "example" or "exemplary" are used herein to mean serving as an example, case, or illustration. Aspects or configurations described herein as "example" or "exemplary" are not necessarily to be understood as preferred or advantageous over other aspects or configurations. Rather, the use of the words "example" or "exemplary" is intended to present concepts in a concrete way. As used in this patent application, the term "or" is intended to mean an inclusive "or" rather than an exclusive "or." That is to say, unless otherwise specified or clearly evident from the context, "X includes A or B" is intended to mean any of the natural inclusive permutations. That is to say, if X includes A, X includes B, or X includes both A and B, then in all of the aforementioned cases, "X includes A or B" is satisfied.In addition, articles such as "a" and "an" as used in this application and the appended claims should generally be understood as meaning "one or more," unless otherwise specified or the context clearly indicates a singular form. Furthermore, the consistent use of the terms "an embodiment" or "an implementation" should not imply that the same embodiment or implementation is meant, unless described as such.

[0120] The embodiments described herein may also relate to an apparatus for performing the operations described herein. This apparatus may be specially manufactured for the required purposes or may include a general-purpose computer that is selectively activated or reconfigured by a computer program stored in the computer. Such a computer program may be stored on a non-transitory, computer-readable storage medium, such as, but not limited to, any type of disk, including floppy disks, optical disks, CD-ROMs and magneto-optical disks, read-only memory (ROMs), random-access memory (RAMs), EPROMs, EEPROMs, magnetic or optical cards, flash memory, or any type of medium suitable for storing electronic instructions. The term "computer-readable storage medium" should be understood to mean a single medium or multiple media (e.g.,The term "computer-readable medium" includes a central or decentralized database and / or associated caches and servers that store one or more sets of instructions. The term "computer-readable medium" is also to be understood as including any medium capable of storing, encoding, or carrying a set of instructions for execution by the machine, and which causes the machine to carry out one or more methodologies of the present embodiments. Accordingly, the term "computer-readable storage medium" is to be understood as including, but not limited to, solid-state storage media, optical media, magnetic media, and any medium capable of storing a set of instructions for execution by the machine, and which causes the machine to carry out one or more methodologies of the present embodiments.

[0121] The algorithms and displays presented herein are not inherently connected to any particular computer or other apparatus. Various general-purpose systems can be used with programs in accordance with the teachings herein, or it may prove expedient to construct a more specialized apparatus to carry out the necessary procedural steps. The required structure for many of these systems will be evident from the description below. Furthermore, the present embodiments are not described with reference to any particular programming language. It is understood that many programming languages ​​can be used to implement the teachings of the embodiments as described herein.

[0122] The description above presents numerous specific details, such as examples of specific systems, components, methods, and so on, to provide a good understanding of several embodiments of the present disclosure. However, it will be clear to a person skilled in the art that at least some embodiments of the present disclosure can be carried out without these specific details. In other cases, well-known components or methods are not described in detail or are presented in a simple block diagram format to avoid unnecessarily obscuring the present embodiments. The specific details set out above are therefore merely exemplary. Certain implementations may differ from these exemplary details and still be considered to be included within the scope of the present embodiments.

[0123] It is understood that the above description is intended to be illustrative and not limiting. Many other embodiments will be clear to those skilled in the art after reading and understanding the above description. The scope of the embodiments should therefore be determined with reference to the attached claims together with the full scope of equivalents to which such claims are entitled.

Claims

[1] A method (1100) comprising the following: Measuring (1102) on a first channel (224A) of a processing device (116) a first signal (234) indicating a touch object (102) near a first electrode layer (106), wherein the first signal (234) includes a touch data component and a first noise component (232A) generated by a noise source (112); Measuring (1104) on a second channel (224B) of the processing device (116) a second signal (236) which includes a second noise component (232B) generated by the noise source (112), wherein the second channel (224B) is coupled to a second electrode (108); Generating (1106) an estimated noise signal using the second noise component (232B) of the second signal (236) associated with the second channel (224B), wherein the estimated noise signal is an estimate of the first noise component (232A) of the first signal (234); and Subtracting (1108) the estimated noise signal from the measured first signal (234) to obtain the touch data component of the first signal (234). [2] Method (1100) according to claim 1, wherein the measurement (1102) of the first signal (234) on the first channel (224A) is performed simultaneously with the measurement (1104) of the second signal (236) on the second channel (224B). [3] Method (1100) according to claim 1, wherein the measuring (1102) of the first signal (234) indicating the contact object (102) near the electrode layer (106) comprises: Buffering the first signal (234) using a first buffer (218A) of the first channel (224A); and Integrating the buffered first signal; and wherein measuring (1104) the second signal (236), which includes the second noise component (232B) generated by the noise source (112), The following is included: Buffering the second signal (236) using a second buffer (218B) of the second channel (224B); and Integrating the buffered second signal. [4] Method (1100) according to claim 1, wherein generating the estimated noise signal using the second noise component (232B) of the second signal (236) associated with the second channel (224B) comprises: Attenuation of the second signal (236) by a damping coefficient to generate the estimated noise signal. [5] Method (1100) according to claim 1, further comprising: Determining a damping coefficient that is used to generate the estimated noise signal. [6] Method (1100) according to claim 5, further comprising: Determining that a temperature value satisfies a temperature threshold, wherein the determination of the attenuation coefficient used to generate the estimated noise signal is performed in response to determining that the temperature value satisfies the temperature threshold. [7] Method (1100) according to claim 5, wherein determining (1200) the attenuation coefficient used to generate the estimated noise signal comprises: Determine (1202) that the noise source (112) is active; Setting (1206) the damping coefficient to a predetermined value; Measuring (1208), on the first channel (224A) of the processing device (116), a third signal that includes a third noise component; Measuring (1210), on the second channel (224B) of the processing device (116), a fourth signal that includes a fourth noise component; and Estimating (1212) the attenuation coefficient using the third signal and the fourth signal. [8] Method (1100) according to claim 1, wherein the noise source 112) generates a noise signal (126) which includes the first noise component (232A) and the second noise component (232B). [9] Method (1100) according to claim 1, wherein the noise source (112) includes a display device. [10] Method (1100) according to claim 1, wherein the second electrode (108) is arranged between the noise source (112) and the first electrode layer (106). [11] A processing device (116) comprising the following: a first channel (224A, 424A) to measure a first signal (234) indicating a contact object (102) near a first electrode layer (106), wherein the first signal (234) includes a contact data component and a first noise component (232A) generated by a noise source (112); and a second channel (224B, 424B) to measure a second signal (236) which includes a second noise component (232B) generated by the noise source (112), wherein the second channel (224B, 424B) is coupled to a second electrode layer (108); and wherein the processing device (116): using the second noise component (232B) of the second signal (236) associated with the second channel (224B, 424B), generates an estimated noise signal, wherein the estimated noise signal is an estimate of the first noise component (232A) of the first signal (234); and subtracts the estimated noise signal from the measured first signal (234) to obtain the touch data component of the first signal (234). [12] Processing device (116) according to claim 11, wherein the first channel (224A, 424A) and the second channel (224B, 424B) serve to measure the first signal (234) and the second signal (236) simultaneously, respectively. [13] Processing device (116) according to claim 11, wherein the processing device (116) in order to generate the estimated noise signal using the second noise component (232B) of the second signal (236) associated with the second channel (224B, 424B) attenuates the second signal (236) by an attenuation coefficient to generate the estimated noise signal. [14] Processing device (116) according to claim 11, wherein the processing device (116) further serves to determine an attenuation coefficient which is used to generate the estimated noise signal, wherein the processing device (116) serves to determine the attenuation coefficient as follows: Determine that the noise source (112) is active; Setting the damping coefficient to a predetermined value; Measure on the first channel (224A, 424A) of the processing device (116), a third signal that includes a third noise component; Measure on the second channel (224B, 424B) of the processing device (116), a fourth signal that includes a fourth noise component; and Estimating the attenuation coefficient using the third signal and of the fourth signal. [15] Processing device (116) according to claim 11, wherein the noise source (112) includes a display device. [16] Processing device (116) according to claim 11, wherein the second electrode layer (108) is arranged between the noise source (112) and the first electrode layer (106). [17] A system (100, 200, 500, 600) that includes the following: a display device (112) for generating a noise signal (126) comprising a first noise component (232B) and a second noise component (232A); a first electrode layer (108) arranged above the display device (112); a second electrode layer (106) arranged above the first electrode layer (108); and a processing device (116) comprising the following: a first channel (224B, 424B) coupled to the first electrode layer (108), wherein the first channel (224B, 424B) serves to measure a first signal (236) which includes the first noise component (232B) generated by the display device (112); and a second channel (224A, 424A) coupled to the second electrode layer (106), wherein the second channel (224A, 424A) serves to measure a second signal (234) indicating a touch object (102) near the second electrode layer (106), wherein the second signal (234) includes a touch data component and the second noise component (232A) generated by the display device (112); and wherein the processing device (116) serves the following purpose: Generating an estimated noise signal using the first noise component (232B) of the first signal (236) associated with the first channel (224B, 424B), wherein the estimated noise signal is an estimate of the second noise component (232A) of the second signal (234); and subtracting the estimated noise signal from the measured second signal (234) to obtain the touch data component of the second signal (234). [18] System (500, 600) according to claim 17, further comprising: a capacitor (541) which is coupled in series with the first channel (224B) and the first electrode layer (108). [19] System (500, 600) according to claim 18, further comprising: a resistor (542) which includes the following: a first connection that is coupled between the first electrode layer (108) and the first channel (224B); and a second connection that is coupled to a ground potential (114). [20] System (500, 600) according to claim 19, wherein at least one of the capacitor (541) or the resistor (542) is integrated into the processing device (116). [21] System (200, 500, 600) according to claim 17, wherein the first channel (224B, 424B) for measuring the first signal (236) which includes the first noise component (232B) generated by the display device (112) comprises the following: a first buffer (218B) to buffer the first signal (236); and a first integrator (220B) to integrate the buffered first signal (236); wherein the second channel (224A, 424A) is used to measure the second signal (234) indicating the contact object (102) near the second electrode layer (106), The following is included: a second buffer (218A) to buffer the second signal (234); and a second integrator (220A) to integrate the buffered second signal (234).

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