Method and apparatus for detecting touch on a capacitive touchscreen

Abstract

A method for detecting a user touch on a capacitive touchscreen may include generating drive signals for drive lines of the capacitive touchscreen. The drive signals are encoded with codes that each specify a polarity of the drive signals at different times. The codes may include a background code that specifies the same polarity for the drive signals, and the remaining codes are orthogonal to the background code and specify that half of the drive signals have a first polarity and half of the drive signals have a second, opposite polarity. The method includes measuring output signals at sense lines of the capacitive touchscreen that include values ​​corresponding to the codes of the drive signals; decoding the output signal by filtering out the values ​​corresponding to the background codes; and determining that a touch has occurred based on the value of the output signal.

Description

[[TECHNICAL FIELD]]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) The present application claims priority to U.S. Non-Provisional Patent Application No. 18 / 436,189 filed on February 8, 2024 and U.S. Provisional Patent Application No. 63 / 444,417 filed on February 9, 2023, the contents of which are incorporated herein by reference in their entirety. [[BACKGROUND ART]]

[0002] (Field of the Invention) The present disclosure relates generally to capacitive touch screens, and more specifically, to detecting touches using DC-free code division multiplexing (CDM). [[SUMMARY OF THE INVENTION]]

[0003] According to aspects of various embodiments, there is provided a method of detecting a user touch on a capacitive touch screen. The method comprises: generating a plurality of drive signals for respectively driving a plurality of drive lines of the capacitive touch screen, wherein the plurality of drive signals are encoded by a plurality of codes that respectively specify polarities of the plurality of drive signals at different times, the plurality of codes include a background code that specifies the same polarity for each drive signal, and the remaining codes among the plurality of codes are orthogonal to the background code; measuring a plurality of output signals on each of a plurality of sensing lines of the capacitive touch screen, wherein each of the plurality of output signals includes a plurality of values corresponding to the plurality of codes of the respective drive signals; and decoding the plurality of output signals to determine that a touch occurs on the capacitive touch screen based on values of the plurality of output signals, wherein the decoding excludes values of the plurality of output signals corresponding to the background code.

[0004] The method may include the step of replacing the values ​​of multiple output signals corresponding to a background code with a replacement value, thereby excluding the values ​​of multiple output signals corresponding to a background code. The replacement value may be zero. The method may include the step of subtracting an offset component from one or more of the multiple output signals corresponding to one or more sensing lines of a capacitive touchscreen. The offset component may correspond to the offset component of the output signal corresponding to the untouched portion of the capacitive touchscreen.

[0005] According to another aspect of various embodiments, a method for detecting user touch on a capacitive touchscreen is provided. The method may include the steps of generating a plurality of drive signals for driving a plurality of drive lines of a capacitive touchscreen, wherein the plurality of drive signals are encoded by a plurality of codes specifying the polarity of the plurality of drive signals at different times, the number of drive lines is greater than the number of codes, the plurality of codes are orthogonal to each other, and each specifies that half of the drive signals have a first polarity and the other half of the drive signals have a second polarity opposite to the first polarity; measuring a plurality of output signals at each of the plurality of sensing lines of the capacitive touchscreen, wherein the plurality of output signals each include a plurality of values ​​corresponding to the plurality of codes of the respective drive signal; and decoding the plurality of output signals to determine that a touch on the capacitive touchscreen has occurred based on the values ​​of the plurality of output signals.

[0006] The method may include the step of subtracting an offset component from one or more output signals corresponding to one or more detection lines of a capacitive touchscreen. The offset component may correspond to the offset component of the output signal corresponding to the untouched portion of the capacitive touchscreen.

[0007] According to another aspect of various embodiments, a method for detecting user touch on a capacitive touchscreen is provided. The method may include the steps of generating a plurality of drive signals for driving a plurality of drive lines of a capacitive touchscreen, the capacitive touchscreen including at least one drive line that is not driven by any of the drive signals, the plurality of drive signals being encoded by a plurality of codes specifying the polarity of the plurality of drive signals at different times, the plurality of codes including a background code specifying the same polarity for each drive signal, and the remaining codes of the plurality of codes being orthogonal to the background code; measuring a plurality of output signals on each of the plurality of sensing lines of the capacitive touchscreen, the plurality of output signals each including a plurality of values ​​corresponding to the plurality of codes for each drive signal; and decoding the plurality of output signals to determine that a touch on the capacitive touchscreen has occurred based on the values ​​of the plurality of output signals, wherein decoding excludes the values ​​of the plurality of output signals corresponding to the background code.

[0008] The method may include the steps of: determining an offset component based on the output signal of at least one drive line that is not driven by any of the drive signals; and subtracting the offset component from one or more output signals corresponding to one or more sensing lines of a capacitive touchscreen.

[0009] According to various embodiments, a capacitive touchscreen controller is provided for detecting user touch on a capacitive touchscreen. The capacitive touchscreen controller may include a processing circuit for generating a plurality of drive signals to drive a plurality of drive lines of a capacitive touchscreen, each of which is encoded by a plurality of codes specifying the polarity of the plurality of drive signals at different times, the plurality of codes including a background code specifying the same polarity for each drive signal, and the remaining codes of the plurality of codes being orthogonal to the background code; measuring a plurality of output signals on each of the plurality of sensing lines of the capacitive touchscreen, each of which includes a plurality of values ​​corresponding to the plurality of codes of each drive signal; and decoding the plurality of output signals to determine that a touch on the capacitive touchscreen has occurred based on the values ​​of the plurality of output signals, the values ​​of the plurality of output signals corresponding to the background code being excluded for decoding the plurality of output signals.

[0010] The processing circuit may replace the values ​​of multiple output signals corresponding to the background code with a replacement value, thereby excluding the values ​​of multiple output signals corresponding to the background code. The replacement value may be zero. The processing circuit may subtract an offset component from one or more of the multiple output signals corresponding to one or more sensing lines of a capacitive touchscreen.

[0011] According to various embodiments, a capacitive touchscreen controller is provided for detecting user touch on a capacitive touchscreen. The capacitive touchscreen controller may include a processing circuit for generating a plurality of drive signals to drive a plurality of drive lines of a capacitive touchscreen, wherein the plurality of drive signals are encoded by a plurality of codes specifying the polarity of the plurality of drive signals at different times, the number of drive lines is greater than the number of codes, the plurality of codes are orthogonal to each other, and each specifies that half of the drive signals have a first polarity and the other half of the drive signals have a second polarity opposite to the first polarity; measuring a plurality of output signals at each of the plurality of sensing lines of the capacitive touchscreen, wherein the plurality of output signals each include a plurality of values ​​corresponding to the plurality of codes of the respective drive signal; and decoding the plurality of output signals to determine that a touch has occurred on the capacitive touchscreen based on the values ​​of the plurality of output signals.

[0012] The processing circuit may subtract an offset component from one or more output signals corresponding to one or more detection lines of a capacitive touchscreen. The offset component may correspond to the offset component of the output signal corresponding to the untouched portion of the capacitive touchscreen.

[0013] According to various embodiments, a capacitive touchscreen controller is provided for detecting user touch on a capacitive touchscreen. The capacitive touchscreen controller may include a processing circuit for generating a plurality of drive signals to drive a plurality of drive lines of a capacitive touchscreen, wherein the capacitive touchscreen includes at least one drive line that is not driven by any of the drive signals, the plurality of drive signals are encoded by a plurality of codes that specify the polarity of the plurality of drive signals at different times, the plurality of codes include a background code that specifies the same polarity for each drive signal, and the remaining codes of the plurality of codes are orthogonal to the background code, and for measuring a plurality of output signals on each of the plurality of sensing lines of the capacitive touchscreen, wherein the plurality of output signals each include a plurality of values ​​corresponding to the plurality of codes of each drive signal, and for decoding the plurality of output signals to determine that a touch has occurred on the capacitive touchscreen based on the values ​​of the plurality of output signals.

[0014] The processing circuit may replace the values ​​of multiple output signals corresponding to the background code with a replacement value, thereby excluding the values ​​of multiple output signals corresponding to the background code. The replacement value may be zero. The processing circuit may determine the offset component based on the output signal of at least one drive line that is not driven by any of the drive signals, and subtract the offset component from one or more of the multiple output signals corresponding to one or more sensing lines of the capacitive touchscreen.

[0015] According to various embodiments, a capacitive touchscreen controller is provided for detecting user touch on a capacitive touchscreen. The capacitive touchscreen controller may include a processing circuit for generating a plurality of drive signals to drive a plurality of drive lines of a capacitive touchscreen, wherein the capacitive touchscreen includes at least one drive line that is not driven by any of the drive signals, the plurality of drive signals are encoded by a plurality of codes that specify the polarity of the plurality of drive signals at different times, the number of drive lines is greater than the number of codes, the plurality of codes are orthogonal to each other and each specifies that half of the drive signals have a first polarity and the other half of the drive signals have a second polarity opposite to the first polarity; measuring a plurality of output signals at each of the plurality of sensing lines of the capacitive touchscreen, wherein the plurality of output signals each include a plurality of values ​​corresponding to the plurality of codes of the respective drive signals; and decoding the plurality of output signals to determine that a touch has occurred on the capacitive touchscreen based on the values ​​of the plurality of output signals.

[0016] The processing circuit can determine the offset component based on the output signal of at least one drive line that is not driven by any of the drive signals, and subtract the offset component from one or more output signals corresponding to one or more sensing lines of a capacitive touchscreen. [Brief explanation of the drawing]

[0017] [Figure 1A] This document shows an example of a capacitive touchscreen panel and a time interleave detection method, or a time division multiplexing (TDM) implementation, based on prior art. [Figure 1B] Examples of capacitive touchscreen panels and code division multiplexing sensing (CDMS) based on prior art are shown. [Figure 2]This document illustrates sets of codes used to encode multiple drive signals in various embodiments. [Figure 3] The diagram shows 16 output signals from prior art, including the average background screen response component. [Figure 4] The diagram shows 16 output signals with various embodiments that substantially remove the average background screen response component. [Figure 5A] This document describes a method for detecting user touch on a capacitive touchscreen, using various embodiments in which the average background screen response component is substantially removed using background coding. [Figure 5B] This document describes a method for detecting user touch on a capacitive touchscreen using background coding, with various embodiments in which the average background screen response component is substantially removed and the offset component is substantially removed. [Figure 6] Figures of 16 output signals are shown, with the average background screen response component substantially removed and various embodiments including the offset component. [Figure 7] The figure shows 16 output signals from various embodiments that substantially remove the average background screen response component and the offset component. [Figure 8A] This document describes a method for detecting user touch on a capacitive touchscreen by various embodiments in which the average background screen response component is substantially removed by excluding background code. [Figure 8B] This document describes a method for detecting user touch on a capacitive touchscreen by various embodiments in which the average background screen response component is substantially removed by excluding background code, and the offset component is substantially removed. [Figure 9A] This document describes a method for detecting user touch on a capacitive touchscreen, using various embodiments in which the average background screen response component is substantially removed using background coding. [Figure 9B] Shows a method for detecting a user touch on a capacitive touch screen according to various embodiments, wherein an average background screen response component is substantially removed using a background code, and an offset component is substantially removed using an offset component corresponding to at least one drive that does not receive a drive signal. [Figure 10A] Shows a method for detecting a user touch on a capacitive touch screen according to various embodiments, wherein an average background screen response component is substantially removed by excluding a background code. [Figure 10B] Shows a method for detecting a user touch on a capacitive touch screen according to various embodiments, wherein an average background screen response component is substantially removed by excluding a background code, and an offset component is substantially removed using an offset component corresponding to at least one drive that does not receive a drive signal. [Figure 11] Shows a capacitive touch screen controller for detecting a user touch on a capacitive touch screen according to various embodiments. Mode for Carrying Out the Invention

[0018] Reference will now be made in detail to the following various embodiments illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. The following embodiments can be embodied in various forms without being limited to the embodiments described herein.

[0019] Figures 1A and 1B show two embodiments of a capacitive touchscreen 100 and a detection method according to the prior art. The capacitive touchscreen 100 may be coupled to a touchscreen controller (not shown), which may be used together to detect the presence and location of a touch or the proximity of an object within the touch-sensing area of ​​the touchscreen panel 100. In this specification, a reference to a touchscreen panel may, where appropriate, encompass both the touchscreen and its touchscreen controller. Similarly, a reference to a touchscreen controller may, where appropriate, encompass both the touchscreen controller and its touchscreen panel. The capacitive touchscreen 100 may, where appropriate, include one or more touch-sensing areas. The capacitive touchscreen 100 may include an array of transmit (TX) or "drive" electrodes 120 and receive (RX) or "sens" electrodes 110 (or an array of a single type of electrode) disposed on one or more substrates which may be made of dielectric material. In this specification, a reference to a touchscreen panel may, where appropriate, encompass both the electrodes of the touchscreen panel and the substrate on which these electrodes are mounted. Alternatively, a reference to a touchscreen panel may, where appropriate, encompass the electrodes of the touchscreen panel but not the substrate on which these electrodes are mounted. In addition, references to “drive lines” or “sensing lines” in this specification refer to “drive electrodes” and “sensing electrodes,” respectively, and vice versa.

[0020] The electrode may be the area of ​​a conductive material forming a shape such as a disc, square, rectangle, other preferred shape, or a preferred combination thereof. One or more cuts in one or more layers of the conductive material may (at least partially) create the shape of the electrode, and the area of ​​the shape may (at least partially) be bounded by those cuts. In certain embodiments, the conductive material of the electrode may occupy approximately 100% of the area of ​​the shape. In some examples, but not limited to them, the electrode may be made of indium tin oxide (ITO), and the ITO of the electrode may, where appropriate, occupy approximately 100% of the area of ​​the shape (sometimes referred to as 100% filling). In certain embodiments, the conductive material of the electrode may substantially occupy less than 100% of the area of ​​the shape. As an example, and not limited to, the electrodes may be made of a fine line of metal (FLM) of a metal or other conductive material, such as copper, silver, or a copper or silver-based material, and the fine line of conductive material may occupy approximately 5% of the area of ​​its shape in hatching, mesh, or other suitable patterns.

[0021] The mechanical stack may include a substrate (or a number of substrates) and a conductive material forming the drive electrode 120 and the sensing electrode 110 of the capacitive touchscreen 100. As an example, and not limited to the examples, the mechanical stack may include a first layer of optically clear adhesive (OCA) beneath the cover panel. The cover panel may be clear and may be made of an elastic material suitable for repeated contact, such as glass, polycarbonate, or poly(methyl methacrylate) (PMMA). This disclosure intends any suitable cover panel made of any suitable material. The first layer of OCA may be disposed between the cover panel and the substrate having the conductive material forming the drive electrode 120 or the sensing electrode 110. The mechanical stack may also include a second layer of OCA and a dielectric layer (which may be made of PET or another suitable material, similar to the substrate having the conductive material forming the other of the drive electrode 120 or the sensing electrode 110). Alternatively, where appropriate, a thin coating of dielectric material may be applied instead of the second layer of OCA and the dielectric layer. The second layer of OCA may be disposed between the dielectric layer and a substrate having a conductive material that constitutes the other of the drive electrode 120 or the sensing electrode 110, and the dielectric layer may be disposed between the second layer of OCA and the gap between the display of the device including the capacitive touchscreen 100 and the touchscreen controller. In examples only, and not limited to, the cover panel may have a thickness of approximately 1 mm, the first layer of OCA may have a thickness of approximately 0.05 mm, the substrate having a conductive material that forms the drive electrode 120 or the sensing electrode 110 may have a thickness of approximately 0.05 mm, the second layer of OCA may have a thickness of approximately 0.05 mm, and the dielectric layer may have a thickness of approximately 0.05 mm. This disclosure describes a particular mechanical stack made of a particular material and having a particular number of particular layers having a particular thickness, but this disclosure intends to describe any preferred mechanical stack made of any preferred material and having any preferred number of any preferred layers having any preferred thickness.

[0022] The capacitive touchscreen 100 may implement a hybrid capacitive form of touch detection, which may include both mutual capacitance detection mode and self-capacitance detection mode of the capacitive sensor. In an example of a mutual capacitance implementation or operating mode, the capacitive touchscreen 100 may include an array of drive electrodes 120 and sensing electrodes 110 that form an array of capacitive nodes. Overlapping regions of the drive electrodes 120 and sensing electrodes 110 may form capacitive nodes. The drive electrodes 120 and sensing electrodes 110 that form capacitive nodes may be close to each other but not electrically in contact with each other. Instead, the drive electrodes 120 and sensing electrodes 110 may be capacitively coupled to each other across the space between them. A pulsed voltage or AC voltage applied to the drive electrode 120 (by the touchscreen controller) may induce a charge on the sensing electrode 110, and the amount of the induced charge may be susceptible to external influences (such as touch or proximity of an object). When an object comes into contact with or approaches a capacitive node, a change in capacitance may occur in the capacitive node, and the touchscreen controller may measure this change in capacitance. By measuring the change in capacitance across the entire array, the touchscreen controller can determine the location of a touch or proximity within the touch detection area of ​​the capacitive touchscreen 100.

[0023] In self-capacitance implementations or operating modes, a touchscreen panel may include an array of single-type electrodes, each capable of forming a capacitive node. In some embodiments, the touchscreen panel may include an array (not shown) of driven electrodes and ground electrodes, where the overlap of the regions between the driven electrodes and ground electrodes forms a capacitive node. When an object touches or approaches a capacitive node, a change in self-capacitance may occur at the capacitive node, and the touchscreen controller may measure this change in capacitance as, for example, a change in the amount of charge required to raise the voltage at the capacitive node by a predetermined amount. Similar to mutual capacitance implementations, by measuring the change in capacitance across the entire array, the touchscreen controller may determine the location of a touch or proximity within the touch-sensing area of ​​the touchscreen panel. Where appropriate, this disclosure intends any preferred form of capacitive touch sensing.

[0024] As described above, a change in capacitance at a capacitive node of a touchscreen panel may indicate a touch or proximity input at the location of the capacitive node. A touchscreen controller may detect and process the change in capacitance to determine the presence and location of a touch or proximity input. The touchscreen controller may then transmit information about the touch or proximity input to one or more other components of the device, including the touchscreen panel and touchscreen controller (such as one or more central processing units, CPUs), which can respond to the touch or proximity input by initiating a function of the device (or an application running on the device). While this disclosure describes a specific touchscreen controller having specific functionality with respect to a particular device and a particular touchscreen panel, this disclosure intends to describe any suitable touchscreen controller having any suitable functionality with respect to any suitable device and any suitable touchscreen panel.

[0025] The touchscreen controller may include processing circuits, which may include one or more integrated circuits (ICs), such as general-purpose microprocessors, microcontrollers, programmable logic devices or arrays, or application-specific ICs (ASICs). In various embodiments, the touchscreen controller may include, for example, a computer system having a processor, memory, storage, and a communication interface. In various embodiments, the touchscreen controller may include analog circuits, digital logic, and digital non-volatile memory. In various embodiments, the touchscreen controller may be disposed on a flexible printed circuit (FPC) bonded to the substrate of the touchscreen panel, as described below. The FPC may be active or passive, where appropriate. In certain embodiments, multiple touchscreen controllers may be disposed on the FPC. The touchscreen controller may include a processor, a drive circuit, a sensing circuit, and a storage circuit. The drive circuit may supply drive signals to the drive electrodes 120 of the capacitive touchscreen 100. The sensing circuit may detect the charge at the capacitive nodes of the touchscreen panel and provide the processor with a measurement signal representing the capacitance at the capacitive nodes. The processor may control the supply of drive signals to the drive electrodes 120 by the drive circuit and process the measurement signal from the sensing circuit to detect and process the presence and location of touch or proximity input within the touch sensing area of ​​the capacitive touchscreen 100. The processor may also track changes in the position of touch or proximity input within the touch sensing area of ​​the capacitive touchscreen 100. The storage circuit may store programming for execution by the processor, including programming for controlling the drive circuit to supply drive signals to the drive electrodes, programming for processing the measurement signal from the sensing circuit, and, where appropriate, other suitable programming.While this disclosure describes a specific touchscreen controller having a specific implementation example with certain components, this disclosure intends to describe any suitable touchscreen controller having any suitable implementation example with any suitable components.

[0026] Referring again to Figure 1A, an example of a time-interleaved detection method, or time-division multiplexing (TDM), is shown according to the prior art. Figure 1B shows an example of a code-division multiplexing detection (CDMS) method according to the prior art. A touch sensor system using a time-division multiplexing (TDM) method on the drive line 120 requires that pairs of drive line 120 and detection line 110 ("drive-detection pairs") be scanned separately at different times to detect pulses transmitted sequentially with multiple drive signals 130A. Therefore, these methods may limit the amount of detection time (Ts) that can be allocated to each drive-detection pair in the touch sensor. In addition, touch sensor designs using TDM may not adequately handle noise signals that may appear on the detection line due to environmental or other types of interference. This may lead to a decrease in the signal-to-noise ratio (SNR) of the detected signal.

[0027] Various embodiments of this disclosure may incorporate a CDM to improve the SNR of the detected signals and allow for an additional detection time Ts for each pair of drive lines 120 and detection lines 110. As shown in Figure 1B, the detection time Ts in embodiments incorporating a CDM can be much longer than the detection time in systems using a TDM. This is because a CDM system can allow for the temporal coexistence of transmissions of multi-line drive signals 130 while remaining fully identifiable at the receiver. In other words, the codes assigned to the drive signals 130 in a CDM system distinguish those particular drive signals 130 from other drive signals 130 of the capacitive touchscreen 100, whereas a TDM system requires the drive signals 130 to be transmitted between separate time windows so that they can be distinguished from one another.

[0028] Figure 2 illustrates a set of codes used to encode multiple drive signals in various embodiments. Referring to Figure 2, multiple drive lines 120 (X0, X1, X2, and X3) can receive multiple drive signals 130 encoded according to multiple codes 210 (code A, code B, code C, and code D), which may be referred to herein as a “code set”. In this embodiment, four drive lines 120 are used for simplification, but any other suitable number of drive lines 120 may be used (e.g., 16, 32, 64, etc.). The multiple codes 210 may be in any suitable form, but in the embodiment of Figure 2, the codes 210 include square waveforms having positive and negative signals. For example, code A indicates that a positive signal (1, 1, 1, 1) is applied simultaneously to each of the four exemplary drive lines 120. In some embodiments, the individual signals of a code are called chips, and therefore all chips of Code A have the same polarity. After the transmission of Code A, Code B, which is transmitted simultaneously on each of the four exemplary drive lines 120, indicates that a positive signal is applied to drive lines X0 and X1 and a negative signal is applied to drive lines X2 and X3: (1, 1, -1, -1). After the transmission of Code B, Code C, which is transmitted simultaneously on each of the four exemplary drive lines 120, indicates that a positive signal is applied to drive lines X0 and X3 and a negative signal is applied to drive lines X1 and X2: (1, -1, -1, 1). After the transmission of Code C, Code D, which is transmitted simultaneously on each of the four exemplary drive lines 120, indicates that a positive signal is applied to drive lines X0 and X2 and a negative signal is applied to drive lines X1 and X3: (1, -1, 1, -1). Each of the multiple codes 210 may contain any number of drive pulses per code. For example, code A may include three positive pulses applied to each drive line 120, followed by code B, which may include three positive pulses applied to drive lines X0 and X1 and three negative pulses applied to drive lines X2 and X3, but is not limited to these. According to exemplary embodiments, each code may be orthogonal to each of the other codes, and as a result, the resulting signals can be decoded without interference.

[0029] Multiple output signals 220A may be measured at multiple detection lines 110 for each code, as shown herein as outA, outB, outC, and outD. Each of the output signals 220A may contain components of each drive signal 130 corresponding to the applied code. For example, output signal outA may contain components outX0, outX1, outX2, and outX3, respectively. According to the embodiment shown in Figure 2, output signal components outX0, outX1, outX2, and outX3 have the same positive output signal component value outA, regardless of amplitude. In contrast, output signal outB corresponding to codeB contains output signal component values ​​+outB, +outB, -outB, and -outB for output signal components outX0, outX1, outX2, and outX3, respectively. Output signals outC and outD similarly have two positive output signal component values ​​and two negative output signal component values.

[0030] The output signal 220A may include components from three or more sources, namely (1) the average background screen response when no touch is present on the capacitive touchscreen 100, (2) the variation in the background screen response when no touch is present on the capacitive touchscreen 100, and (3) the touch from the touchscreen panel. Figure 3 shows a diagram of 16 output signals 220 according to the prior art. As shown in Figure 3, the output signals 220 include the average background screen response 310, which constitutes the maximum component of each output signal 220. Some of the output signals 220 include a touch response component 320, indicated by a dip in the output signal 220, which indicates that a touch has occurred on their drive line 120, but the touch response component 320 is substantially smaller than the average background screen response component 310. The touchscreen controller functions to detect touches on the touchscreen panel and therefore wastes resources measuring the average background screen response component 310 of the output signal 220 in addition to the touch response component 320 of the output signal 220.

[0031] Referring back to Figure 2, some of the multiple codes 210 (i.e., code B, code C, and code D) are balanced by having the same number of positive and negative output signal components. In contrast, Code A consists of chips with uniform polarity. In the case of balanced codes, the measured output signals outB, outC, and outD substantially cancel out the average background screen response component 310, and contain substantially only the touch response component 320 and variations in the background response. In contrast, the output signal outA corresponding to code A contains four positive output signal components, which substantially represent the undesirable average background screen response component 310, i.e., the "DC" component. As mentioned above, the codes are orthogonal to each other. When decoding the results, aspects of the present disclosure omit the output signal 220A resulting from the transmission of codeA, i.e., outX0 = +outB, +outC + outD, outX1 = +outB, -outC, -outD, outX2 = -outB, -outC, +outD, and outX3 = -outB, +outC, -outD. By excluding the output signal values ​​corresponding to codeA when decoding the signal, the undesirable average background screen response component 310 can be substantially removed from the measured output signal 220, which saves resources for detecting the touch response component 320 in the measured output signal 220, which is referred to herein as DC-free measurement.

[0032] For example, Figure 4 shows 16 measured output signals 220A from various embodiments, where the average background screen response component 310 is substantially removed by omitting the output signal 220A resulting from the transmission of codeA during decoding. Compared to the y-axis scale in Figure 3, the y-axis scale in Figure 4 is much smaller because the average background screen response component 310 is not included in the measured output signal 220. As shown in Figure 4, the touch response component 320 is the largest component of the measured output signal 220. Therefore, touches on the capacitive touchscreen 100 can be detected more easily with the average background screen response component 310 substantially removed.

[0033] This disclosure includes various embodiments of a method for detecting user touch on a capacitive touchscreen that can substantially remove the average background screen response component. For example, Figure 5A illustrates a method for detecting user touch on a capacitive touchscreen according to various embodiments. This method may include step 510 of generating a plurality of drive signals to drive a plurality of drive lines of a capacitive touchscreen 100, each of which is a drive signal. The plurality of drive signals may be encoded by a plurality of codes that specify the polarity of the plurality of drive signals at different times, each of which is a code.

[0034] For example, as explained in relation to Figure 2, codeA may specify the polarity of the drive signal 130 applied to the drive line 120. CodeB may then specify the polarity of the drive signal 130 applied to the drive line 120 after codeA. CodeC and CodeD are used to specify the polarity of the drive signal 130 applied to the drive line 120 after codeB. As described above, the multiple codes may include a background code (e.g., codeA) that specifies the same polarity for each drive signal 130, and that polarity may be positive or negative. The remaining codes (e.g., codeB, codeC, and codeD) may be orthogonal to the background code (e.g., the dot product of the background code (e.g., codeA) and each of the remaining codes (e.g., codeB, codeC, and codeD) is zero), and may specify that half of the drive signals have a first polarity and the other half have a second polarity opposite to the first polarity. For example, codeB, codeC, and codeD specify positive polarity for two drive signals and negative polarity for two drive signals, respectively. Since the background code specifies the same polarity for all drive signals 130, the average background screen response component, or DC component 310, is included in the background code. The remaining codes are orthogonal to the background code, so the remaining codes do not include the average background screen response component.

[0035] The method may also include step 520 of measuring multiple output signals 220A at each of the multiple sensing lines 110 of the capacitive touchscreen 100. Each of the multiple output signals 220A may contain multiple values ​​corresponding to multiple codes 210 of the respective drive signals 130. For example, for a capacitive touchscreen having 16 drive lines, driven by 16 drive signals encoded using 16 codes that specify the polarity of the drive signals for each drive line, the output signal for each sensing line may have 16 values ​​corresponding to the 16 drive lines.

[0036] The method may include step 530 of decoding multiple output signals and determining, based on the values ​​of the multiple output signals, that a touch has occurred on a capacitive touchscreen. For example, the output signal 220A of each sensing line may be vector multiplied by each of the multiple codes 210 to obtain a contribution from each driving line 120. According to various embodiments, the value of the output signal 220A corresponding to a background code (i.e., the value of the output signal measured when the background code is applied to the driving signal) may be excluded to remove the average background screen response component 310. According to various embodiments, the decoding step 530 may include the steps of replacing the values ​​of the multiple output signals 220A corresponding to the background codes with a substitution value, and decoding the multiple output signals 220A based on the substitution value and the values ​​of the multiple output signals 220A corresponding to the remaining codes of the multiple codes 210. According to various embodiments, the substitution value may be zero, but other values ​​may be used.

[0037] Figure 5B shows various embodiments of methods for detecting user touch on a capacitive touchscreen. The method in Figure 5B is an extension of the method in Figure 5A, and the steps described above in relation to Figure 5A are not repeated here. In the method in Figure 5B, after the decoding step 530, in step 540, an offset component is subtracted from one or more of the multiple output signals. As will be described in more detail below, according to various embodiments, the offset component may correspond to the offset component of the output signal corresponding to the untouched portion of the capacitive touchscreen.

[0038] For example, Figure 6 shows diagrams of 16 output signals 220A in various embodiments, with the average background screen response component 310 substantially removed and an offset component 610 included. Referring to Figure 6, as described above, by substantially removing the average background screen response component 310 of the output signal 220A, the touch response component 320 becomes the largest component of the output signal 220A. However, by substantially removing the average background screen response component 310 (in Figure 3), an offset component 610 may be introduced across various drive lines 120 when a touch is present, as shown in Figure 6. The amplitude of the offset component 610 may be opposite to the amplitude of the touch response component 320, which can complicate the processing required to determine the touch position from the measured output signal 220.

[0039] The offset component 610 of the measured output signal may include one or more offset components corresponding to the drive lines 120. For example, offset components 610a and 610b correspond to drive lines 120 located near both sides of the capacitive touchscreen. As shown in Figure 6, the touch data 320 indicates a touch that occurred between the drive lines 120 corresponding to offset components 610a and 610b. The offset component 610 corresponding to the drive line where the touch occurred reduces the touch response component 320, which can make it more difficult to detect the touch response component 320. To substantially remove the offset component 610 from the output signal 220A corresponding to the drive line 120 where the touch occurred on the capacitive touchscreen 100, it may be possible to subtract the offset component, for example, 610a or 610b, from the untouched portion of the capacitive touchscreen 100. The offset component 610 of the touched portion of the capacitive touchscreen 100 can be substantially removed by subtracting the offset component 610a or 610b of the untouched portion of the capacitive touchscreen 100 from the offset component 610 of the touched portion of the capacitive touchscreen 100. For example, Figure 7 shows a diagram of 16 output signals with the offset component 610 removed. As shown in Figure 7, the touch response component 320 is greater than the touch response component in Figure 6 because the offset component 610 has been removed. However, since new touches can occur at any time, there is no way to guarantee that the "untouched" portion of the touchscreen panel remains untouched when the offset component of that portion of the screen is used to subtract the offset component from the touched portion of the capacitive touchscreen 100.

[0040] Therefore, it may be necessary to identify untouched lines to provide an offset component, but these lines do not contain touch data. An exemplary method for identifying untouched lines is described below.

[0041] Figure 8A shows a method for detecting user touch on a capacitive touchscreen according to various embodiments. The method in Figure 8A is similar to the method in Figure 5A, except that no background code is generated for use with the drive signals 120. For example, in step 810, multiple drive signals 130 are generated to drive multiple drive lines 120 of the capacitive touchscreen 100, each of them. The multiple drive signals may be encoded by multiple codes 210, each specifying the polarity of the drive signals 130 at different times. The number of drive lines 120 may be greater than the number of codes 210. For example, the capacitive touchscreen may have 16 drive lines 120, and the multiple codes 210 may consist of 15 codes, each having 16 chips. In contrast to the method in Figure 5A, the multiple codes 210 in Figure 8A may exclude a background code that specifies the same polarity for each drive signal 120. The multiple codes used in the method shown in Figure 8A may be orthogonal to each other, and each may specify that half of the drive signal has a first polarity and the other half of the drive signal has a second polarity opposite to the first polarity.

[0042] The method in Figure 8A may include step 820 of measuring multiple output signals 220A at each of the multiple detection lines 110 of the capacitive touchscreen 100. Each of the multiple output signals 220A may contain multiple values ​​corresponding to multiple codes 210 for each of the drive signals 130. By excluding background codes and using one fewer code than the number of drive lines, the output signals 220 do not contain the average background screen response component 310. In step 830, one or more of the multiple output signals 220A are decoded and, as described above, it is determined that a touch has occurred on the capacitive touchscreen 100 based on the values ​​of the multiple output signals.

[0043] Figure 8B shows various embodiments of methods for detecting user touch on a capacitive touchscreen. The method in Figure 8B is an extension of the method in Figure 8A, and the steps described above in relation to Figure 8A are not repeated here. In the method in Figure 8B, after the decoding step 830, in step 840, an offset component is subtracted from one or more of the multiple output signals 220A. As described above, according to various embodiments, the offset component may correspond to the offset component 610b of the output signal 220A corresponding to the untouched portion of the capacitive touchscreen 100. According to various embodiments, the offset component may correspond to the offset component of the output signal corresponding to at least one drive line to which a drive signal is not applied or is at least partially absent.

[0044] Figure 9A illustrates a method for detecting user touch on a capacitive touchscreen according to various embodiments. The method in Figure 9A is similar to the method in Figure 5A, except that one of the drive lines 120 is not driven by a drive signal 130. The method in Figure 9A may include a step 910 to generate a plurality of drive signals to drive a plurality of drive lines of a capacitive touchscreen 100, each of which may be driven by a plurality of drive lines. The capacitive touchscreen 100 may include at least one drive line 120 that is not driven by any of the drive signals 130. The plurality of drive signals 130 may be encoded by a plurality of codes 210 that specify the polarity of the plurality of drive signals 130 at different times. The plurality of codes 210 include a background code that specifies the same polarity for each drive signal 130. The remaining codes of the plurality of codes 210 may be orthogonal to the background code and may specify that half of the drive signals have a first polarity and the other half have a second polarity opposite to the first polarity.

[0045] The method in Figure 9A may include step 920 of measuring multiple output signals 220A at each of the multiple sensing lines 110 of the capacitive touchscreen 100. Each of the multiple output signals 220A may contain multiple values ​​corresponding to multiple codes 210 of the respective drive signals 130. For example, for a capacitive touchscreen with 16 drive lines, driven by 15 drive signals encoded using 16 codes that specify the polarity of the drive signals for each drive line, the output signals for each sensing line would be 16 values ​​corresponding to the 16 drive lines.

[0046] The method may include a step 930 of decoding multiple output signals and determining that a touch has occurred on a capacitive touchscreen based on the values ​​of the multiple output signals 220. For example, the output signal 220A of each detection line may be vector multiplied by each of the multiple codes 210 to obtain a contribution from each drive line 120. According to various embodiments, the value of the output signal 220A corresponding to a background code (i.e., the value of the output signal measured when the background code is applied to the drive signal) may be excluded to remove the average background screen response component 310. According to various embodiments, the decoding step 930 may include a step of substituting the values ​​of the multiple output signals 220A corresponding to the background codes with a substitution value, and a step of decoding the multiple output signals 220A based on the substitution value and the values ​​of the multiple output signals 220A corresponding to the remaining codes of the multiple codes 210. According to various embodiments, the substitution value may be zero, but other values ​​may be used.

[0047] Figure 9B shows a method for detecting user touch on a capacitive touchscreen according to various embodiments. The method in Figure 9B is an extension of the method in Figure 9A, and the steps described above in relation to Figure 9A are not repeated here. In the method in Figure 9B, after the decoding step 930, in step 940, an offset component is determined based on the output signal 220A of at least one drive line that is not driven by any of the drive signals 130, and the determined offset component is subtracted from one or more of the multiple output signals 220. Even if the multiple codes 210 are not applied to one of the drive lines 120, the multiple codes 210 can be used to decode the output signals. For example, in the case of a capacitive touchscreen with 16 drive lines, 15 of the drive lines 120 may be driven by 15 drive signals 130 encoded using the multiple codes 210. The output signal 220A still includes the values ​​of the 16 drive lines (the values ​​of the 15 drive lines driven by the drive signals and the value of the one drive line not driven by the drive signals). According to various embodiments, drive lines not driven by a drive signal can be disconnected. The output signal 220A of a drive line that is neither driven nor disconnected includes an offset component 610b but does not include a touch component 320. Therefore, the offset component 610b can be subtracted from the output signals 220A corresponding to the other 15 drive lines without affecting any touch information 320.

[0048] Figure 10A shows a method for detecting user touch on a capacitive touchscreen according to various embodiments. The method in Figure 10A is similar to the method in Figure 8A in that no background code is used to encode the drive signals 120, and is similar to the method in Figure 9A in that one of the drive lines 120 is not driven by the drive signal 130. For example, in step 1010, multiple drive signals 130 are generated to drive multiple drive lines 120 of the capacitive touchscreen 100, each of them. The multiple drive signals may be encoded by multiple codes 210, each specifying the polarity of the drive signal 130 at different times. The number of drive lines 120 may be greater than the number of codes 210. For example, the capacitive touchscreen may have 16 drive lines 120, and the multiple codes 210 may contain 15 codes. The multiple codes 210 in Figure 10A may exclude a background code that specifies the same polarity for each drive signal 120. The multiple codes 210 used in the method of Figure 10A may be orthogonal to each other, and each may specify that half of the drive signal has a first polarity and the other half of the drive signal has a second polarity opposite to the first polarity.

[0049] The method in Figure 10A may include step 1020 of measuring multiple output signals 220A at each of the multiple detection lines 110 of the capacitive touchscreen 100. Each of the multiple output signals 220A may contain multiple values ​​corresponding to multiple codes 210 for each of the drive signals 130. By excluding background codes and using one fewer code than the number of drive lines, the output signals 220A do not contain the average background screen response component 310. In step 1030, one or more of the multiple output signals 220A are decoded and, as described above, it is determined that a touch has occurred on the capacitive touchscreen 100 based on the values ​​of the multiple output signals.

[0050] Figure 10B shows a method for detecting user touch on a capacitive touchscreen according to various embodiments. The method in Figure 10B is an extension of the method in Figure 10A, and the steps described above in relation to Figure 10A are not repeated here. In the method in Figure 10B, after the decoding step 1030, in step 1040, an offset component is determined based on the output signal 220A of at least one drive line that is not driven by any of the drive signals 130, and the determined offset component is subtracted from one or more of the multiple output signals 220. Even if the multiple codes 210 are not applied to one of the drive lines 120, the multiple codes 210 can be used to decode the output signals. For example, in the case of a capacitive touchscreen with 16 drive lines, 15 of the drive lines 120 may be driven by 15 drive signals 130 encoded using the multiple codes 210. The output signal 220A still includes the values ​​of the 16 drive lines (the values ​​of the 15 drive lines driven by the drive signal, and the value of the one drive line not driven by the drive signal). According to various embodiments, the drive line not driven by the drive signal may be disconnected. The output signal 220A of the drive line that is neither driven nor disconnected includes an offset component 610b but does not include a touch component 320. Thus, the offset component 610b can be subtracted from the output signal 220A corresponding to the other 15 drive lines without affecting any touch information 320.

[0051] Figure 11 shows a capacitive touchscreen controller for detecting user touch on a capacitive touchscreen according to various embodiments. The capacitive touchscreen controller 1110 may include a processing circuit 1120, which may include one or more integrated circuits (ICs), such as a general-purpose microprocessor, microcontroller, programmable logic device or array, or application-specific IC (ASIC), as described above. In various embodiments, the capacitive touchscreen controller 1110 may include a computer system having processing circuits such as a processor, memory, storage, and communication interface. In various embodiments, the capacitive touchscreen controller 1110 may include analog circuits, digital logic, and digital non-volatile memory. According to various embodiments, the processing circuit 1120 may perform the methods described in relation to Figures 5A, 5B, 8A, 8B, 9A, 9B, 10A, and 10B, which are not repeated here to avoid redundancy.

[0052] In connection with the above description and drawings, various embodiments have been disclosed herein. It will be understood that it would be excessively repetitive to literally describe and illustrate every combination and partial combination of these embodiments. Therefore, all embodiments can be combined in any way and / or combination, and this specification, including the drawings, shall be construed as constituting a complete written description of all combinations and partial combinations of the embodiments described herein, as well as the methods and processes for creating and using them, and shall support the claims for any such combination or partial combination.

[0053] Those skilled in the art will understand that the embodiments described herein are not limited to those specifically shown and described above. Furthermore, unless otherwise stated above, it should be noted that all accompanying drawings are not to scale. Various modifications and variations are possible in light of the above teachings.

Claims

1. A method for detecting user touch on a capacitive touchscreen, wherein the method is: A step of generating a plurality of drive signals for driving a plurality of drive lines of the capacitive touchscreen, wherein the plurality of drive signals are encoded by a plurality of codes that specify the polarity of the plurality of drive signals at different times, the plurality of codes include a background code that specifies the same polarity for each of the drive signals, and the remaining codes of the plurality of codes are orthogonal to the background code, A step of measuring a plurality of output signals in each of the plurality of detection lines of the capacitive touchscreen, wherein each of the plurality of output signals includes a plurality of values ​​corresponding to the plurality of codes of the respective drive signals. A method comprising the steps of decoding the plurality of output signals and determining that a touch has occurred on the capacitive touchscreen based on the values ​​of the plurality of output signals, wherein the decoding excludes the values ​​of the plurality of output signals corresponding to the background code.

2. The method according to claim 1, comprising the step of replacing the values ​​of the plurality of output signals corresponding to the background code with replacement values, thereby excluding the values ​​of the plurality of output signals corresponding to the background code.

3. The method according to claim 2, wherein the substitution value is zero.

4. The method according to claim 1, further comprising the step of subtracting an offset component from one or more of the plurality of output signals corresponding to one or more detection lines of the capacitive touchscreen.

5. The method according to claim 4, wherein the offset component corresponds to the offset component of the output signal corresponding to the untouched portion of the capacitive touchscreen.

6. A method for detecting user touch on a capacitive touchscreen, wherein the method is: A step of generating a plurality of drive signals for driving a plurality of drive lines of the capacitive touchscreen, wherein the plurality of drive signals are encoded by a plurality of codes specifying the polarity of the plurality of drive signals at different times, the number of drive lines is greater than the number of codes, the plurality of codes are orthogonal to each other, and each specifies that half of the drive signals have a first polarity and the other half of the drive signals have a second polarity opposite to the first polarity, A step of measuring a plurality of output signals in each of the plurality of detection lines of the capacitive touchscreen, wherein each of the plurality of output signals includes a plurality of values ​​corresponding to the plurality of codes of each of the drive signals, A method comprising the step of decoding the plurality of output signals and determining that a touch has occurred on the capacitive touchscreen based on the values ​​of the plurality of output signals.

7. The method according to claim 6, further comprising the step of subtracting an offset component from one or more of the plurality of output signals corresponding to one or more detection lines of the capacitive touchscreen.

8. The method according to claim 7, wherein the offset component corresponds to the offset component of the output signal corresponding to the untouched portion of the capacitive touchscreen.

9. A method for detecting user touch on a capacitive touchscreen, wherein the method is: A step of generating a plurality of drive signals for driving a plurality of drive lines of the capacitive touchscreen, wherein the capacitive touchscreen includes at least one drive line that is not driven by any of the drive signals, the plurality of drive signals are encoded by a plurality of codes that specify the polarity of the plurality of drive signals at different times, the plurality of codes include a background code that specifies the same polarity for each of the drive signals, and the remaining codes of the plurality of codes are orthogonal to the background code, A step of measuring a plurality of output signals in each of the plurality of detection lines of the capacitive touchscreen, wherein each of the plurality of output signals includes a plurality of values ​​corresponding to the plurality of codes of the respective drive signals. A method comprising the steps of decoding the plurality of output signals and determining that a touch has occurred on the capacitive touchscreen based on the values ​​of the plurality of output signals, wherein the decoding excludes the values ​​of the plurality of output signals corresponding to the background code.

10. The method according to claim 9, comprising the step of replacing the values ​​of the plurality of output signals corresponding to the background code with replacement values, thereby excluding the values ​​of the plurality of output signals corresponding to the background code.

11. The method according to claim 10, wherein the substitution value is zero.

12. A step of determining the offset component based on the output signal of at least one drive line that is not driven by any of the aforementioned drive signals, The method according to claim 9, comprising the step of subtracting the offset component from one or more of the plurality of output signals corresponding to one or more detection lines of the capacitive touchscreen.

13. A method for detecting user touch on a capacitive touchscreen, wherein the method is: A step of generating a plurality of drive signals for driving a plurality of drive lines of the capacitive touchscreen, wherein the capacitive touchscreen includes at least one drive line that is not driven by any of the drive signals, the plurality of drive signals are encoded by a plurality of codes that each specify the polarity of the plurality of drive signals at different times, the number of drive lines is greater than the number of codes, the plurality of codes are orthogonal to each other, and each specifies that half of the drive signals have a first polarity and the other half of the drive signals have a second polarity opposite to the first polarity, A step of measuring a plurality of output signals in each of the plurality of detection lines of the capacitive touchscreen, wherein each of the plurality of output signals includes a plurality of values ​​corresponding to the plurality of codes of each of the drive signals, A method comprising the step of decoding the plurality of output signals and determining that a touch has occurred on the capacitive touchscreen based on the values ​​of the plurality of output signals.

14. A step of determining the offset component based on the output signal of at least one drive line that is not driven by any of the aforementioned drive signals, The method according to claim 13, comprising the step of subtracting the offset component from one or more of the plurality of output signals corresponding to one or more detection lines of the capacitive touchscreen.

15. A capacitive touchscreen controller for detecting user touch on a capacitive touchscreen, wherein the capacitive touchscreen controller is It includes a processing circuit, and the processing circuit is The method involves generating a plurality of drive signals for driving a plurality of drive lines of the capacitive touchscreen, wherein the plurality of drive signals are encoded by a plurality of codes that specify the polarity of each of the plurality of drive signals at different times, the plurality of codes include a background code that specifies the same polarity for each of the drive signals, and the remaining codes of the plurality of codes are orthogonal to the background code. Measuring multiple output signals in each of the multiple detection lines of the capacitive touchscreen, wherein each of the multiple output signals includes multiple values ​​corresponding to the multiple codes of the respective drive signals. A capacitive touchscreen controller for decoding the plurality of output signals and determining that a touch has occurred on the capacitive touchscreen based on the values ​​of the plurality of output signals, wherein the values ​​of the plurality of output signals corresponding to the background code are excluded in order to decode the plurality of output signals.

16. The capacitive touchscreen controller according to claim 15, wherein the processing circuit replaces the values ​​of the plurality of output signals corresponding to the background code with replacement values, thereby excluding the values ​​of the plurality of output signals corresponding to the background code.

17. The capacitive touchscreen controller according to claim 16, wherein the substitution value is zero.

18. The aforementioned processing circuit is The capacitive touchscreen controller according to claim 15, for subtracting an offset component from one or more of the plurality of output signals corresponding to one or more detection lines of the capacitive touchscreen.

19. A capacitive touchscreen controller for detecting user touch on a capacitive touchscreen, wherein the capacitive touchscreen controller is It includes a processing circuit, and the processing circuit is The method for generating a plurality of drive signals to drive a plurality of drive lines of the capacitive touchscreen, wherein the plurality of drive signals are encoded by a plurality of codes that specify the polarity of the plurality of drive signals at different times, the number of drive lines is greater than the number of codes, the plurality of codes are orthogonal to each other, and each specifies that half of the drive signals have a first polarity and the other half of the drive signals have a second polarity opposite to the first polarity. Measuring multiple output signals in each of the multiple detection lines of the capacitive touchscreen, wherein each of the multiple output signals includes multiple values ​​corresponding to the multiple codes of each of the drive signals. A capacitive touchscreen controller for decoding the plurality of output signals and determining that a touch has occurred on the capacitive touchscreen based on the values ​​of the plurality of output signals.

20. The capacitive touchscreen controller according to claim 19, wherein the processing circuit is for subtracting an offset component from one or more of the plurality of output signals corresponding to one or more detection lines of the capacitive touchscreen.

21. The capacitive touchscreen controller according to claim 20, wherein the offset component corresponds to the offset component of the output signal corresponding to the untouched portion of the capacitive touchscreen.

22. A capacitive touchscreen controller for detecting user touch on a capacitive touchscreen, wherein the capacitive touchscreen controller is It includes a processing circuit, and the processing circuit is The method of generating a plurality of drive signals for driving a plurality of drive lines of the capacitive touchscreen, wherein the capacitive touchscreen includes at least one drive line that is not driven by any of the drive signals, the plurality of drive signals are encoded by a plurality of codes that specify the polarity of the plurality of drive signals at different times, the plurality of codes include a background code that specifies the same polarity for each of the drive signals, and the remaining codes of the plurality of codes are orthogonal to the background code. Measuring multiple output signals in each of the multiple detection lines of the capacitive touchscreen, wherein each of the multiple output signals includes multiple values ​​corresponding to the multiple codes of the respective drive signals. A capacitive touchscreen controller for decoding the plurality of output signals and determining that a touch has occurred on the capacitive touchscreen based on the values ​​of the plurality of output signals.

23. The capacitive touchscreen controller according to claim 22, wherein the processing circuit replaces the values ​​of the plurality of output signals corresponding to the background code with replacement values, thereby excluding the values ​​of the plurality of output signals corresponding to the background code.

24. The capacitive touchscreen controller according to claim 23, wherein the substitution value is zero.

25. The aforementioned processing circuit is Based on the output signal of the at least one drive line that is not driven by any of the aforementioned drive signals, the offset component is determined. The capacitive touchscreen controller according to claim 22, for subtracting the offset component from one or more of the plurality of output signals corresponding to one or more detection lines of the capacitive touchscreen.

26. A capacitive touchscreen controller for detecting user touch on a capacitive touchscreen, wherein the capacitive touchscreen controller is It includes a processing circuit, and the processing circuit is Generating a plurality of drive signals for driving a plurality of drive lines of the capacitive touchscreen, wherein the capacitive touchscreen includes at least one drive line that is not driven by any of the drive signals, the plurality of drive signals are encoded by a plurality of codes that each specify the polarity of the plurality of drive signals at different times, the number of drive lines is greater than the number of codes, the plurality of codes are orthogonal to each other, and each specifies that half of the drive signals have a first polarity and the other half of the drive signals have a second polarity opposite to the first polarity, Measuring multiple output signals in each of the multiple detection lines of the capacitive touchscreen, wherein each of the multiple output signals includes multiple values ​​corresponding to the multiple codes of each of the drive signals. A capacitive touchscreen controller for decoding the plurality of output signals and determining that a touch has occurred on the capacitive touchscreen based on the values ​​of the plurality of output signals.

27. The aforementioned processing circuit is Based on the output signal of the at least one drive line that is not driven by any of the aforementioned drive signals, the offset component is determined. The capacitive touchscreen controller according to claim 26, for subtracting the offset component from one or more of the plurality of output signals corresponding to one or more detection lines of the capacitive touchscreen.

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