Touch screen display and operating method thereof

Abstract

The invention relates to a touch screen display and a method of operating the same. A method for operating an electronic device includes simultaneously performing a mutual sampling scan on a first portion of a touch screen and a noise sampling scan on a second portion of the touch screen larger than the first portion; detecting a noise value from the second portion of the touch screen; comparing the noise value with a predetermined frequency value of a touch controller; and adjusting the predetermined frequency value when at least one of the noise values exceeds the predetermined frequency value.

Description

TECHNICAL FIELD

[0001] The present disclosure relates generally to systems and methods for operating a display, and in particular embodiments to touch screen displays. BACKGROUND

[0002] Electronic devices designed for user interaction have historically utilized external input devices such as keyboards, keypads, and / or mice to capture user input. In recent years, this has been furthered from more traditional methods due to consumer preference for the convenience of portable devices that can support a more flexible lifestyle. To this end, smaller portable handheld electronic devices such as mobile phones, tablets, gaming systems, and the like have increased. This has led to the proliferation of touch screens and touch screen displays as a system for capturing user input. They not only provide the functionality of traditional electronic devices, but touch screens provide additional features. For example, given the appropriate software, a user can use a touch screen for sketching, drawing, and various handwriting applications.

[0003] Organic light emitting diodes (OLEDs) provide higher performance displays. OLED displays provide high contrast self-emissive displays with low driving voltage and high luminous efficiency. However, OLED displays have their own advantages and disadvantages.

[0004] A display panel of an OLED-based touch screen can include a plurality of pixels arranged in rows and columns in a matrix-like fashion on a display layer. Each pixel can include an OLED configured to produce light based on a current driven therethrough. During operation, the touch screen can be refreshed (e.g., updated) in each of a plurality of display frames defined by a vertical synchronization signal (Vsync). During each display frame, each row of pixels is sequentially updated and a touch sensing scan (e.g., mutual and self-sensing scans) is performed.

[0005] The display panel can display images that include zebra noise. Zebra noise, also known as zebra pattern noise or stripe noise, is a visual artifact that can appear on a touch screen display. When zebra noise is displayed on a touch screen, the black areas are low voltage areas on the touch screen and the white areas are high voltage areas on the touch screen. The high and low voltages are dense and have an effect on the capacitance values sensed by the touch screen, resulting in additional noise. Each zebra image produces a unique noise frequency that can cause ghost touches. SUMMARY

[0006] In one embodiment, a method for operating an electronic device includes simultaneously performing mutual sampling scans on a first portion of a touchscreen and noise sampling scans on a second portion of the touchscreen, the second portion being larger than the first portion of the touchscreen, detecting noise values from the second portion of the touchscreen, comparing the noise values to a predetermined frequency value of a touch controller, and adjusting the predetermined frequency value when at least one of the noise values exceeds the predetermined frequency value.

[0007] In one embodiment, a method for operating an electronic device includes displaying an image on a plurality of portions of a touchscreen, the plurality of portions including a first portion and a second portion, the second portion being larger than the first portion; performing mutual sampling scans on the first portion of the display by driving a first TX channel during a first time period; performing first noise sampling scans on the second portion of the display by a plurality of non-driven TX channels during the first time period to collect noise data; determining a first noise frequency from the second portion of the display; and setting a noise frequency threshold based on the first noise frequency.

[0008] In one embodiment, a device includes a display layer having a plurality of pixels, a touch sensing layer adjacent to the display layer, the touch sensing layer having a plurality of sensors, each sensor being associated with one or more of the pixels (circuitry), a touch controller, and a non-transitory memory storing a program to be executed by the touch controller, the program including instructions to perform the steps of simultaneously performing mutual sampling scans on a first portion of the display layer and noise sampling scans on a second portion of the display layer, the second portion being larger than the first portion of the display layer, detecting noise values from the second portion of the display layer, comparing the noise values to a predetermined frequency value of the touch controller, and adjusting the predetermined frequency value when at least one of the noise values exceeds the predetermined frequency value. BRIEF DESCRIPTION OF DRAWINGS

[0009] For a more complete understanding of the present disclosure and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings in which:

[0010] Figure 1A A component diagram of an electronic device is shown;

[0011] Figure 1B A component diagram of a display of an electronic device is shown;

[0012] Figure 1C A component diagram of a display stack of an electronic device is shown;

[0013] Figure 1D A component diagram of a touchscreen of an electronic device is shown;

[0014] Figure 2A A schematic diagram showing a conventional electronic device and a sample scan on the electronic device is shown;

[0015] Figure 2B A touch sensing layer during a mutual sample scan is shown;

[0016] Figure 2C A touch sensing layer during a noise sample scan is shown; Figure 2D A timing diagram showing a conventional mutual sample scan is shown;

[0017] Figure 3A - Figure 3B A schematic diagram showing an electronic device that prevents artifact touches according to various embodiments is shown;

[0018] Figure 4A A schematic diagram showing an electronic device that prevents artifact touches according to one embodiment is shown;

[0019] Figure 4B A timing diagram showing an electronic device that prevents artifact touches according to various embodiments is shown;

[0020] Figure 5 A process flow for preventing artifact touches according to embodiments of the present application is shown; and

[0021] Figure 6 A process flow for preventing artifact touches according to embodiments of the present application is shown. DETAILED DESCRIPTION

[0022] A conventional organic light emitting diode (OLED) device can include a display that can include a plurality of pixels arranged in rows and columns across the display layer in a matrix-like fashion. During operation, the OLED display can be refreshed in each of a plurality of frames distinguished by the frequency of a vertical synchronization signal (Vsync). The OLED display can be updated by sequentially refreshing each row of pixels from the top to the bottom of the display in each frame according to a horizontal synchronization signal (Hsync).

[0023] A mutual sample scan is performed on a touchscreen of an OLED display to determine a user touch. The sensitivity of the mutual sample scan depends on various noise sources. When the background noise is high, the sensitivity of the mutual sample will be lower because the touch must introduce a significant change in mutual capacitance above the detection limit. Typically, the mutual sample can be performed over a range of frequencies. However, in practice, the noise data can be different at different scan frequencies used for the mutual sample. The exact frequency with the lowest noise data cannot be determined a priori.

[0024] When there is significant noise when performing mutual sampling scans, the results of the mutual sampling can detect false touches unless the sensitivity of the mutual sampling is significantly reduced by increasing the detection limit. In other words, when nothing is touching the touch screen, a touch on the touch screen can be detected. This is referred to as an artifact touch. During normal operation, when a color image is being displayed on the touch screen, the horizontal sync signal (Hsync) has a strong effect on the display. The typical frequency of the noise present on the touch screen is close to the value of Hsync. When the mutual sampling scan used to detect touches to the touch screen is performed at the same frequency as the noise of the touch screen, an artifact touch can occur.

[0025] Conventionally, to prevent artifact touches when displaying a zebra image (any pattern of black and white), a noise sampling scan can be performed in each of a plurality of frames. The noise sensing scan is typically performed between the self-sensing scan and the mutual sampling scan in each frame. During the noise sampling scan, noise data corresponding to each of a plurality of frequencies on the display is detected. Due to the duration of the frame, the duration of the self-sensing scan, and the duration of the mutual sampling scan, the noise sampling scan is performed for a limited amount of display time. Also, because the display is updated line by line, the noise sampling scan is performed on only the portion of the touch screen that is updated during the noise sampling scan.

[0026] However, a zebra (black and white) image on the touch screen includes a high voltage region displaying white on the display and a low voltage region displaying black on the display. The contrast array of the voltages is encapsulated in a small region and can cause a change in the sensed capacitance on the touch screen. Furthermore, the noise from such a zebra image varies with frequency. Therefore, to minimize the noise generated from the zebra image, the frequency with the lowest noise value in the noise sampling scan is selected, and the subsequent mutual sampling scan is performed at the selected frequency. This is referred to as hopping.

[0027] However, in some cases, only a portion of the displayed image includes the zebra pattern. For example, the portion of the display or frame that is performing the noise sampling scan can not have the zebra pattern, while the rest of the portion being displayed can include the zebra pattern. In this case, the noise sampling scan does not detect the zebra pattern, and therefore the system is unaware of the associated higher noise. As a result, the display can select a frequency that is not appropriate for the zebra pattern. Therefore, the noise associated with the zebra pattern, i.e., the zebra pattern noise, can cause false detections and result in artifact touches.

[0028] Embodiments relate to dynamic noise sampling for un-specified display noise. Embodiments of the present application disclose a method for simultaneously performing a mutual sampling scan and a noise sampling scan to determine noise frequencies on different portions of a display to prevent false touch. In other words, the portions of the display that are scanned during the noise sampling scan change during each scan, increasing the coverage of the noise sampling scan on the display.

[0029] Figure 1A - Figure 1D An electronic device according to embodiments of the present application is shown, Figure 1A A component diagram of an electronic device is shown, Figure 1B A component diagram of a display of an electronic device is shown, Figure 1C A component diagram of a display stack of an electronic device is shown, and Figure 1D A component diagram of a touch screen of an electronic device is shown.

[0030] Reference is made to Figure 1A The electronic device 100 can include a touch screen 102, a touch controller 104, and a system on chip 106. The electronic device 100 can be a smart phone, a GPS device, a tablet computer, a mobile media player, a laptop computer, a gaming system, a personal computer, or any other electronic device that can utilize a touch sensitive display.

[0031] The touch screen 102 can be an organic light emitting diode (OLED) display, an LED display, or any other type of display. The touch screen 102 can include a plurality of pixels in a display layer configured to display images. As understood by one of ordinary skill in the art, the display layer of the touch screen 102 can include a plurality of pixels at each intersection between a data line and a scan line. The plurality of scan lines can extend across rows of the touch screen 102 in a matrix-like configuration, and the data lines extend across columns of the touch screen 102.

[0032] The touch screen 102 can also include a touch sensing layer configured to detect touches made on the touch screen 102. This will be shown in more detail below.

[0033] The touch controller 104 can perform various methods with respect to the display. In various embodiments, the touch controller 104 can be a processor that analyzes information and executes a series of executable scripts, for example, stored in the memory 110. In one or more embodiments, the processor can include an application specific integrated circuit (ASIC) device, a central processing unit (CPU), or any other processing unit known in the art. In various embodiments, the touch controller 104 can include a plurality of separate computing units, for example, cores integrated within one processor, or different separate processing chips.

[0034] In various embodiments, the touch controller 104 can include an analog block 108 and a digital block 112. The analog block 108 can include a plurality of analog circuits configured to measure capacitance on the touch screen 102 and convert them to digital values. The digital block 112 can include various digital logic circuits, e.g., DACs or digital control systems, configured to obtain digital touch data from the analog block 108, process the digital touch data, and store them into the memory 110.

[0035] Further details of the operation of the touch screen 102 and the touch controller 104 according to various embodiments are discussed below.

[0036] The memory 110 can be programmed for short-term and / or long-term memory storage. The memory 110 can include various programs to be executed in the touch controller 104. The memory 110 can include volatile and non-volatile memories. The memory 110 is designed to hold information generated by the touch controller 104, so it can be called upon later.

[0037] In various embodiments, the system-on-chip 106 can also be referred to as an application processor, and can include processors, interfaces, circuits, etc. configured to direct input and output data streams to the touch screen 102 and the associated touch controller 104. The system-on-chip 106 can be configured to transmit image data and synchronization signals to the touch controller 104. In other words, the system-on-chip 106 can be configured to transmit image data corresponding to a plurality of frames on an image.

[0038] In various embodiments, the synchronization signals transmitted by the system-on-chip 106 can include a horizontal synchronization signal (Hsync) and a vertical synchronization signal (Vsync). The touch controller 104 can receive image data based on the Hsync and transmit the processed image data to pixels on the touch screen 102, and update the displayed image based on the Vsync. In other words, each time the Vsync is transmitted, a frame of the image that is currently being displayed can be refreshed to the next frame of the image.

[0039] As understood by one of ordinary skill in the art, a frame of the displayed image can be refreshed (e.g., updated) in each of a plurality of display frames defined by the Vsync. A frame of the displayed image can be refreshed when the Vsync is transmitted (i.e., logic high). Thus, the frequency of the Vsync distinguishes each frame.

[0040] During each frame, the touch controller 104 can sequentially update each row of pixel circuits according to the Hsync. The touch controller 104 can update each row of pixels of the display from top to bottom according to the Hsync of each frame. In other words, different rows of pixels can be updated (i.e., be logic high) each time the Hsync is transmitted. Thus, the Hsync has a higher frequency than the Vsync.

[0041] Additionally, the touch controller 104 can be configured to detect touches on the touch screen 102 via the touch screen. In other words, the touch controller 104 can be configured to transmit touch drive signals (TDS) to the touch screen, receive touch sense signals (TSS) as a return from the touch screen, process the TSS to determine touch coordinates, and report them to the system on chip 106. The touch controller 104 can then use the touch screen to determine touch coordinates based on the touch data collected from the scan and report them to the system on chip 106. The system on chip 106 can then provide output to the touch screen 102 based on the reported touch coordinates.

[0042] As understood by one of ordinary skill in the art, when there is noise on the touch screen 102, the cross-sampling scan can detect artifact touches on the touch screen 102 when performed at the same frequency as the noise.

[0043] Noise can be generated on the touch screen 102 based on the brightness of the color generated by each pixel. The brighter the color of the pixel, the higher the voltage. In normal operation, when a color image is displayed on the touch screen, the high frequency Hsync has a strong impact on the noise on the display. In other words, the frequency of the noise on the touch screen typically follows the Hsync. Thus, the frequency of the cross-sampling scan can be configured to avoid the Hsync.

[0044] However, when a zebra (black and white) pattern is displayed, the increase in variation between the high voltage in the white areas and the low voltage in the black areas creates additional noise. Each zebra image can generate noise on the touch screen 102 that peaks at a frequency that is different from the frequency of the Hsync, and the frequency used in the cross-sampling scan can not be easily avoided.

[0045] Conventionally, to avoid performing the cross-sampling scan at the frequency where the noise has a maximum (or generally high), a noise sampling scan is performed in each frame. The noise sampling scan is typically performed once in each frame along with the self-sensing scan and the cross-sampling scan. To have enough time to perform each scan, the noise sampling scan is performed during a portion of each frame.

[0046] The noise sampling scan is typically performed on a plurality of different frequencies. This allows noise data to be determined for each different frequency. The frequency with the lowest noise value can then be used as the frequency at which to perform the mutual sampling scan. This allows the mutual sampling scan to be changed so as to be performed at a frequency different from the frequency of the peak noise caused by the zebra pattern.

[0047] Because the touchscreen 102 is updated row by row, and due to time constraints, the noise sampling scan is typically performed on only a small portion of the touchscreen 102. Traditionally, the noise sampling scan is performed at the same start time in each frame and on the same portion of the touchscreen 102.

[0048] In cases where the portion of the touchscreen 102 being scanned does not indicate that a zebra pattern is being displayed, frequency hopping will not occur. For example, when an image with a zebra pattern is being displayed but the scanned portion of the display is only the white (or black) portion of the display, the noise data of the image can be miscalculated. In other words, in each noise sampling scan, the touch controller will be misled into performing the mutual sampling scan at a frequency with higher noise due to the small noise values generated by the all-white (or all-black) portion of the image. This can result in a false touch.

[0049] Advantageously, embodiments of the present application disclose a method for changing the portion of the display on which the noise sampling scan occurs to prevent false touches. In other words, the portion of the display that is scanned during the noise sampling scan is changed over a period of time, increasing the coverage of the noise sampling scan.

[0050] Figure 1B A schematic of the touchscreen 102 is shown. In various embodiments, the touchscreen 102 can include a touch sensing layer 116 and a display layer 118. The touch sensing layer 116 and the display layer 118 can be located on the front face of the electronic device 100.

[0051] Figure 1C A display stack of the touchscreen 102 is shown. The display stack of the touchscreen 102 can include a plurality of layers. In various embodiments, the touchscreen 102 can include a cover film 120, a touch sensing layer 116, a core 122, an encapsulation film 124, and an OLED layer 126.

[0052] The OLED layer 126 can include a plurality of OLED elements (e.g., pixels) formed in a matrix-like form across rows and columns of the touchscreen. The OLED elements can be configured to transmit light having a color (e.g., red, green, or blue) having a brightness based on a current at which they are driven to display each frame of an image. As described above, the colors and brightness displayed by the OLED elements are refreshed in a display frame according to a vertical synchronization signal (Vsync) and a horizontal synchronization signal (Vsync).

[0053] A encapsulation film 124 can be formed and in direct contact with the OLED layer 126. The encapsulation film 124 can be used to prevent oxygen, water, or humidity from reaching the OLED layer 126 from external sources and damaging the OLED layer 126. The encapsulation film 124 can include one or more layers of material. For example, the encapsulation film 124 can include silicon dioxide, silicon nitride, or any other encapsulation film known in the art.

[0054] A core 122 can be formed on the encapsulation film 124. The core 122 can be used to control characteristics of the touch screen 102, such as external light reflection, color accuracy, brightness, etc. For example, the core 122 can include multiple layers, such as a reflection control layer that includes color filters, a lens layer that corresponds to each OLED element of the OLED layer, etc.

[0055] A touch sensing layer 116 can be formed on the core 122. The touch sensing layer 116 can be a capacitive touch panel configured to detect touches made to the touch screen 102. This will be explained in more detail below. However, it should be clear that noise generated at the OLED layer 126 can be picked up at the touch sensing layer 116.

[0056] A cover film 114 can be a protective layer to protect the touch sensing layer 116. The cover film 114 can include a thin layer of transparent material, such as glass that includes silicon dioxide.

[0057] Figure 1C The display stack described in the middle is for example purposes only and is not limiting of this application. Additional layers known in the art can also be included in the display stack of the touch screen 102.

[0058] While discussed herein with respect to OLEDs, it should be understood that other technologies can be utilized. For example, the touch screen displays disclosed herein can incorporate display technologies such as LEDs (light emitting diodes), LCDs (liquid crystal displays), and AMOLEDs (active-matrix organic light-emitting diodes), as well as OLEDs.

[0059] Figure 1D A schematic of the touch sensing layer 116 is shown. In various embodiments, the touch sensing layer 116 can include drive lines Dr1-Dr4 and sense lines SS1-SS4 that cross the entirety of the touch sensing layer 116 in a grid-like manner and are operable by the touch controller 104. In various embodiments, the drive lines Dr1-Dr4 can be formed as rows across the touch sensing layer 116 and the sense lines SS1-SS4 can be formed as columns across the touch sensing layer 116. In other embodiments, the drive lines Dr1-Dr4 can be formed in columns across the touch sensing layer 116 and the sense lines SS1-SS4 can be formed in columns across the touch sensing layer 116. In various embodiments, the number of drive lines can be equal to the number of sense lines. Although in the example shown in FIG. 1, the touch sensing layer 116 includes four drive lines Dr1-Dr4 and four sense lines SS1-SS4, it should be understood that the touch sensing layer 116 can include any number of drive lines and sense lines. Figure 1DFour drive lines and four sense lines are shown in the middle, but this does not represent the number of drive lines and sense lines that can exist on the touch sensing layer. The number of drive lines and sense lines used is not limited by this application.

[0060] In certain embodiments, the drive lines Dr1-Dr4 and the sense lines SS1-SS4 can overlap. Although Figure 1D Drive lines Dr1-Dr4 and sense lines SS1-SS4 are described as overlapping in a crosswise manner, they can overlap in a manner other than crosswise, such as staggered or at various angles.

[0061] Drive lines Dr1-Dr4 and sense lines SS1-SS4 can have a measurable mutual capacitance at their intersections so as to form a mutual capacitance matrix having mutual capacitances 134.

[0062] In various embodiments, the drive lines Dr1-Dr4 can be coupled to the drive circuit 130 and the sense lines SS1-SS4 can be coupled to the sense circuit 128 of the touch controller 104. As understood by one of ordinary skill in the art, each of the drive lines and sense lines can also have a measurable self-capacitance 136. In other words, the drive lines Dr1-Dr4 and the sense lines SS1-SS4 can be operated in a mutual sampling mode and a self-sensing mode.

[0063] Figure 2A - Figure 2D A diagram of a conventional electronic device is shown that uses a noise sampling scan to prevent false touch, where Figure 2A A diagram of a conventional electronic device and sampling scans on the electronic device is shown, Figure 2B A touch sensing layer during a mutual sampling scan is shown, Figure 2C A touch sensing layer during a noise sampling scan is shown, and Figure 2D A timing diagram of a conventional mutual sampling scan is shown.

[0064] Referring to Figure 2A Conventionally, the electronic device 100 performs a self-sampling scan 202, a noise sampling scan (or noise scan) 204, and a mutual sampling scan (mutual scan) 206 for a duration. Each scan is performed in the following order on each portion of the touchscreen: self-sampling scan 202, noise sampling scan 204, and mutual sampling scan 206. Each scan is typically performed on the same portion of the touchscreen, such as Figure 2A is shown.

[0065] During the self-sampling scan 202 or self-capacitance scan, the touch controller sequentially measures the self-capacitance of each electrode by applying a known signal and measuring the time it takes for the electrode to charge to a particular voltage. When a finger is near or touches the touchscreen, the self-capacitance of nearby electrodes increases.

[0066] The noise sampling scan 204 measures ambient noise to create a noise profile used to clean data in the mutual sampling scan 206. The mutual sampling scan 206 can use the most recent noise data generated by the noise sampling scan 204 to compensate for noise, such as noise caused by a zebra image. As understood by one of ordinary skill in the art, when there is noise on the touchscreen 102 and the mutual sampling scan 206 is performed at the same frequency as the noise, the mutual sampling scan can detect false touch on the touchscreen 102.

[0067] As described above, because the noise sampling scan 204 is performed on the same portion of the touchscreen 102, the frequency selected by the noise sampling scan 204 can not avoid the frequency of the noise caused by the zebra pattern when the zebra pattern is displayed but the sampled portion 210 of the touchscreen 102 does not include the zebra pattern. In other words, even when a zebra image is being displayed on the touchscreen, the portion 210 of the touchscreen 102 being scanned during the noise sampling scan 204 is only displaying white. Because the same portion 210 of the touchscreen 102 is scanned during the noise sampling scan 204 when only white is displayed, the zebra pattern in the image will not be detected and the noise profile will not properly filter noise during the subsequent mutual sampling scan 206.

[0068] Figure 2B The touch sensing layer 116 is shown for the mutual sampling scan 206. Referring to Figure 2B The mutual sampling scan 206 sequentially activates the TX channels (transmitter channels or drive lines) TX1, TX2, TXn to measure the change in capacitance at the intersection with the RX channels (receiver channels or sense lines) RX1, RX2, RXn, enabling accurate multi-touch detection. However, these measurements can be disturbed by ambient noise from the power supply lines, electronic devices, or the display itself.

[0069] Figure 2C The touch sensing layer 116 is shown for the noise sampling scan 204. Referring to Figure 2C During the noise sampling scan 204, the touch controller sets all the TX channels (transmitter channels or drive lines) TX1, TX2, TXn to a high impedance state or grounds them, effectively muting the activation of the touch sensing elements. In this state, the sense lines remain active but are just “listening” to the environment. Any signal detected on these RX channels (receiver channels or sense lines) RX1, RX2, RXn is classified as noise, which can originate from various sources, such as images on the display (i.e., zebra pattern), power supply, nearby electronic devices or chargers, and USB connections.

[0070] Noise scans 204 produce a real-time distribution of noise amplitude and frequency by temporarily disabling all TX channels TX1, TX2, TXn and using RX channels RX1, RX2, RXN to listen to the ambient electrical environment. The touch controller 104 uses the most recent noise distribution to interleave these noise scans 204 with mutual scans 206 to clean mutual capacitance data. It can subtract the noise amplitude in the time domain, use an adaptive filter based on the noise distribution, or employ frequency domain techniques such as a Fourier transform to isolate and remove specific noise frequencies. This continuous noise compensation allows mutual sampling scans 206 to operate with lower touch detection thresholds, reducing false touches and improving multi-touch accuracy. As the device moves between environments, for example from a quiet room to a noisy coffee room near a refrigerator, the noise sampling adapts, ensuring that the accuracy of mutual sampling remains unimpaired.

[0071] The touch controller 104 measures the amplitude and frequency characteristics of the noise on each RX channel RX1, RX2, RXn to create a noise distribution of noise data. The noise data between pixels of the touch screen 102 within a portion 210 of the touch screen 102 can be sampled at different frequencies. For example, noise sampling scans 204 can be performed at 225 kHz, 275 kHz, and 330 kHz. The frequency with the lowest noise data can be selected, and the mutual sampling scans 206 can be performed at that frequency. Other frequencies can be used. In addition, more than three frequencies can be used for noise sampling scans 204.

[0072] The noise distribution is then used to filter or subtract noise from subsequent mutual sampling scans 206 and self-sampling scans 202, either by subtracting the noise amplitude in the time domain or isolating and removing specific noise frequencies in the frequency domain using techniques such as a Fourier transform. By regularly interspersing noise sampling scans 204 between self-sampling scans 202, the touch screen adapts in real-time to changing noise environments, ensuring consistent, accurate, and interference-resistant touch performance across different settings.

[0073] Figure 2D A timing diagram 220 showing a conventional mutual sampling scan 206 is shown. The timing diagram 220 shows TX channels TX1, TX2, TX3, TXn being sequentially driven over an acquisition period. For example, TX channel TX1 is driven and TX channels TX2, TX3, TXn are not driven during a first time period 222a, TX channel TX2 is driven and TX channels TX1, TX3, TXn are not driven during a second time period 222b, TX channel TX3 is driven and TX channels TX1, TX2, TXn are not driven during a third time period 222c, and so on.

[0074] Figure 3A - Figure 3Bschematics of an electronic device and corresponding sample scans to prevent artifact touches are shown. Figure 3A schematics of an electronic device and sample scans on the electronic device during a first time period are shown, Figure 3B schematics of an electronic device and sample scans on the electronic device during a subsequent time period are shown.

[0075] Referring to Figure 3A , the electronic device 100 performs a self-sample scan 302, a mutual-sample scan 306, and a noise-sample scan 304 during a first duration tl on the touch screen 102. The scans can take 5ms to 30ms to complete. For example, in some example embodiments, the first duration tl can be 8ms. In other embodiments, other time durations can be implemented.

[0076] The self-sample scan 302 or self-capacitance scan is performed at the top of the touch screen 102. During the self-sample scan 302, the touch controller sequentially measures the self-capacitance of each electrode by applying a known signal and measuring the time it takes for the electrode to charge to a particular voltage. When a finger is near or touches the touch screen, the self-capacitance of nearby electrodes increases. The self-sample scan 302 can take, for example, from 1ms to 5ms to complete.

[0077] After the self-sample scan 302, a mutual-sample scan 306 is performed on a first portion 310 of the touch screen 102. The mutual-sample scan 306 sequentially drives the TX channels to measure capacitance changes. Referring to Figure 3A , the mutual-sample scan 306 drives a first TX channel TXO during the first time period tl.

[0078] Unlike conventional electronic device scans, the mutual-sample scan 306 can occur before the noise-sample scan 304. The mutual-sample scan 306 can utilize predetermined frequency values stored in the memory 110 of the touch controller 104. During the first duration tl, the predetermined frequency values can be used to set an initial noise profile. The noise profile can be used to filter excess noise detected during the mutual-sample scan 306. By filtering the excess noise, the mutual-sample scan 206 can operate with a lower touch detection threshold, thereby reducing false touches and improving touch accuracy.

[0079] After the mutual sampling scan 306, a noise sampling scan 304 is performed on a second portion 312 of the touchscreen 102. The noise sampling scan 304 utilizes non-driven TX channels (e.g., TX channels TXi to TXn) to collect noise data that can be used during subsequent mutual sampling scans. The second portion 312 of the touchscreen 102 can be larger than the first portion 310 of the touchscreen 102. By performing the noise sampling scan 304 on a larger portion of the touchscreen 102, noise on the display, such as a zebra pattern, can be captured during the noise sampling scan 304.

[0080] The noise data collected from the noise sampling scan 304 can be used to determine a first noise frequency from the second portion 312 of the touchscreen 102. The first noise frequency can be used by the mutual sampling scan to minimize noise generated from the zebra image. The frequency with the lowest noise value in the noise sampling scan is selected as the first noise frequency, and subsequent mutual sampling scans are performed at the first noise frequency.

[0081] Reference Figure 3B The electronic device 300 performs the self-sampling scan 302, the mutual sampling scan 306, a first noise sampling scan 304a, and a second noise sampling scan 304b during a second time duration t2 on the touchscreen 102. During the second time duration t2, the self-sampling scan is performed on the top portion of the touchscreen 102. By driving different TX channels during the second time duration t2, the mutual sampling scan 306 is performed on the first portion 310 of the touchscreen 102. During the second time period, the first noise sampling scan 304a is performed on a first sub-portion 312a of the second portion 312, and the second noise sampling scan 304b is performed on a second sub-portion 312b of the second portion 312.

[0082] The scans begin with the self-sampling scan 302. After the self-sampling scan 302, the first noise sampling scan 304a is performed on the first sub-portion 312a of the second portion 312 of the touchscreen 102. The first noise sampling scan 304a can be performed by the non-driven TX channel TXo on the first sub-portion 312a of the second portion 312 of the touchscreen 102. The first noise sampling scan 304a can also be performed by a first set of non-driven TX channels, for example, if the mutual sampling scan 306 is actively driving the TX channel TXiO, the first noise sampling scan 304a can be performed by the non-driven TX channels TXo to TX9.

[0083] After the first noise sampling scan 304a, the mutual sampling scan 306 is performed on the first portion 310 of the touchscreen 102 by driving the TX channel TXi. The second noise sampling scan 304b can be performed by collecting noise data on the remaining non-driven TX channels TX2 to TXn. Although Figure 3BThe second noise sample scan 304 is shown being read on TX channels TX2 to TXn, but a second noise sample scan 304b can be performed by a second set of non-driven TX channels, for example, if the mutual sample scan 306 actively drives TX channel TX10, then the second noise sample scan 304b can be performed by non-driven TX channels TX11 to TXn.

[0084] Advantageously, to prevent the occurrence of artifact touches, embodiments of the present application simultaneously perform a mutual sample scan and a noise sample scan by driving a TX channel during each time period and by sensing with non-driven TX channels. One advantage of this is that the noise sample scan will be performed on different parts of the display, allowing for detection of zebra images and frequency hopping to prevent artifact touches. Another advantage of this is that the scans can be completed more quickly, as the noise sample scan does not require additional time to collect noise data.

[0085] Figure 4A The touch sensing layer 116 is shown for both the noise sample scan 304 and the mutual sample scan 306. Referring to Figure 4A The mutual sample scan 306 sequentially drives TX channels, measuring the change in capacitance at the intersection with RX channels RX1, RX2, RXn to precisely locate multiple touch points. During each time period that the mutual sample scan 306 is driving a TX channel, the noise sample scan 304 or noise sample scans 304a, 304b collect noise data by setting non-driven TX channels to a high impedance state or grounding them, and the RX channels remain active to detect signals in the environment. The signals detected on these RX channels RX1, RX2, RXn are classified by the touch controller 104 as noise to create a noise profile.

[0086] During the noise sample scan 304, the touch controller 104 measures existing noise on the touch sensor grid without any touch input. This is done by sampling the sensor lines (rows and columns) when their capacitance values are not actively driven. The noise measurements are used to create a “noise profile” or “noise mask” representing the current noise across the entire touch sensing layer 116. The noise profile is essentially a map of noise at different locations on the grid. After obtaining the noise profile, the touch controller 104 performs the mutual sample scan 306 by driving the sensor lines and measuring the change in capacitance. However, instead of using a fixed threshold for touch detection during the mutual sample scan 306, the touch controller 104 compares the touch measurements to the previously obtained noise profile.

[0087] The touch controller 104 interleaves these noise sample scans 304 with mutual sample scans 306, using the most recent noise profile to clean mutual capacitance data. By subtracting the noise profile from the mutual sample values, the touch controller 104 can more accurately distinguish between real touch events and noise fluctuations. Touch events that exceed a certain tolerance of noise (a predetermined threshold) are recorded as valid touches, while smaller deviations within the noise profile are ignored or filtered out. By regularly interspersing noise sample scans 304, the touch screen adapts in real-time to changing noise environments, ensuring consistent, accurate, and interference-resistant touch performance across different settings.

[0088] By compensating for noise fluctuations, the touch controller 104 can more reliably detect and locate touch events, reducing false touches or missed touches caused by external noise. A device using noise sensing can operate more effectively in environments with high levels of electromagnetic interference (EMI) or other noise sources, as the noise is effectively cancelled out during touch detection. Since the noise profile is continuously updated, the touch system can adapt to changes in the noise environment, such as the introduction of new noise sources or changes in existing noise sources.

[0089] Figure 4B A timing diagram 220 is shown that illustrates the mutual sample scans 306 and noise sample scans 304 over an acquisition period. The timing diagram 420 illustrates TX channels TX1, TX2, TX3, TXn being sequentially driven during the acquisition period. For example, TX channel TX1 is driven during a first time period 222a while TX channels TX2, TX3, TXn are not driven, TX channel TX2 is driven during a second time period 222b while TX channels TX1, TX3, TXn are not driven, TX channel TX3 is driven during a third time period 222c while TX channels TX1, TX2, TXn are not driven, TX channel TXn is driven during an nth time period 222n while TX channels TX1, TX2, TX3 are not driven, and so on.

[0090] The noise sample scans 304 are repeated continuously or at regular intervals to account for changes in the noise environment over time. This ensures that the noise profile remains up-to-date and accurately reflects current noise conditions.

[0091] Figure 5 An example process flow 500 for preventing artifact touches according to embodiments of the present application is shown.

[0092] Beginning with block 502, and with reference to Figure 3A - Figure 3BTo describe, the mutual sampling scan 306 and the noise sampling scan 304 are performed simultaneously on the touchscreen 102. In various embodiments, the mutual sampling scan 306 is performed on a first portion 310 of the touchscreen, and the noise sampling scan 304 is performed on a second portion 312 of the touchscreen. The second portion 312 of the touchscreen 102 can be larger than the first portion 310 of the touchscreen 102. The second portion 312 can include a first sub-portion 312a and a second sub-portion 312b. The first sub-portion 312a and the second sub-portion 312b can collectively be larger than the first portion 310 of the touchscreen 102.

[0093] The mutual sampling scan 306 is performed by driving a first TX channel of the plurality of TX channels. The noise sampling scan 304 is performed by collecting noise values by non-driven TX channels of the plurality of TX channels.

[0094] As shown next in block 504, noise values are detected on the second portion 312 of the touchscreen 102. In various embodiments, the noise values are detected on the second portion 312, which is larger than the first portion 310, in order to increase detection of the noise image (e.g., zebra pattern). As shown, the first portion 310 of the touchscreen 102 does not display the zebra pattern, while the second portion 312 of the touchscreen 102 displays a plurality of zebra patterns. By applying the noise sampling scan 304 to the larger second portion 312, false touch can be prevented when the noise sampling scan 304 is performed where the zebra pattern appears. Figure 3A

[0095] As shown in block 506, the noise values detected in block 504 are compared to predetermined frequency values stored in the touch controller 104. The predetermined frequency values sampled by the touch controller 104 are compared to the frequencies generated by the noise values.

[0096] As shown in block 508, when at least one of the noise values detected in block 504 exceeds the predetermined frequency values, the predetermined frequency values stored in the touch controller 104 are adjusted to a frequency corresponding to higher noise. The predetermined frequency values instruct the touch controller 104 to change the predetermined frequency values from a first predetermined frequency setting to a second predetermined frequency setting. The second predetermined frequency setting can be used to perform a subsequent mutual sampling scan.

[0097] Figure 6 An example process flow 600 for preventing false touch is shown in accordance with an embodiment of the present application.

[0098] Starting from block 602, and referring to Figure 3A ​- 3B, an image can be displayed on the touchscreen 102 of the electronic device 100. The touchscreen can include multiple portions. For example, the multiple portions can include a first portion 310 and a second portion 312. The second portion 312 of the touchscreen 102 can be larger than the first portion 310 of the touchscreen 102.

[0099] As shown next in block 604, by driving the first TX channel TXO, a mutual sampling scan 306 is performed on the first portion 310 of the touchscreen during a first time period tl.

[0100] Next as shown in block 606, a first noise sampling scan 304a is performed to collect noise data on the second portion 312 of the touchscreen by multiple non-driven TX channels during the first time period. The second portion 312 of the touchscreen can include a first sub-portion 312a and a second sub-portion 312b. The first portion 310 can be located between the first sub-portion 312a and the second sub-portion 312b. The first noise sampling scan 304a can be performed to collect noise data on the first sub-portion 312a and the second noise sampling scan 304b can be performed to collect noise data on the second sub-portion 312b.

[0101] As shown next in block 608, a first noise frequency is determined from the second portion 312 of the touchscreen 102. The first noise frequency corresponds to the noise data collected in block 606.

[0102] As shown next in block 610, a noise frequency threshold is set based on the first noise frequency determined in block 608. The noise frequency threshold can be used during the mutual sampling scan 306 to prevent false touch. When the noise frequency threshold is set to the first noise frequency determined in block 608, the mutual sampling scan 306 can prevent false touch when a zebra pattern appears on the touchscreen.

[0103] Example embodiments of the present disclosure are summarized here. Other embodiments can also be understood from the entire specification and claims submitted herewith.

[0104] Example 1. A method for operating an electronic device, the method comprising: simultaneously performing a mutual sampling scan on a first portion of a touchscreen and a noise sampling scan on a second portion of the touchscreen, the second portion being larger than the first portion of the touchscreen; detecting noise values from the second portion of the touchscreen; comparing the noise values to a predetermined frequency value of a touch controller; and adjusting the predetermined frequency value when at least one of the noise values exceeds the predetermined frequency value.

[0105] Example 2. The method of example 1, further comprising simultaneously performing a subsequent mutual sampling scan on the first portion of the touchscreen and a subsequent noise sampling scan on the second portion of the touchscreen, wherein the first portion of the touchscreen changes with each subsequent mutual sampling scan and the second portion of the touchscreen changes with each subsequent noise sampling scan.

[0106] Example 3. The method of example 1 or 2, wherein performing the mutual sampling scan comprises driving a first TX channel of a plurality of TX channels, and wherein performing the noise sampling scan comprises collecting the noise values through non-driven TX channels of the plurality of TX channels.

[0107] Example 4. The method of examples 1-3, wherein comparing the noise values comprises determining a predetermined frequency value that a touch controller is sampling, and comparing the noise values to the predetermined frequency value of the touch controller.

[0108] Example 5. The method of examples 1-4, further comprising increasing a touch sensitivity of the touchscreen.

[0109] Example 6. The method of examples 1-5, wherein adjusting the predetermined frequency value comprises instructing the touch controller to change a first predetermined frequency setting to a second predetermined frequency setting based on the noise values.

[0110] Example 7. The method of examples 1-6, further comprising performing a subsequent mutual sampling scan based on the second predetermined frequency.

[0111] Example 8. A method for operating an electronic device, the method comprising: displaying an image on a plurality of portions of a touchscreen, the plurality of portions comprising a first portion and a second portion, the second portion being larger than the first portion; performing a mutual sampling scan on the first portion of the display by driving a first TX channel during a first time period; performing a first noise sampling scan on the second portion of the display by a plurality of non-driven TX channels to collect noise data during the first time period; determining a first noise frequency from the second portion of the display; and setting a noise frequency threshold based on the first noise frequency.

[0112] Example 9. The method of example 8, further comprising performing a second noise sampling scan on a third portion of the plurality of portions during the first time period, the second noise sampling scan being performed prior to the mutual sampling scan.

[0113] Example 10. The method of example 8 or 9, wherein the second portion of the touchscreen comprises a first sub-portion and a second sub-portion, the first portion being located between the first sub-portion and the second sub-portion.

[0114] Example 11. The method of examples 8-10, further comprising: performing a second noise sampling scan and a third noise sampling scan during a second time period, wherein the second noise sampling scan comprises collecting the noise data from a first non-driven TX channel on the first sub-portion, and wherein the third noise sampling scan comprises collecting the noise data from a second non-driven TX channel on the second sub-portion; determining a second noise frequency from a second portion of the touchscreen; comparing the first noise frequency and the second noise frequency; and adjusting the noise frequency threshold when the second noise frequency exceeds the first noise frequency.

[0115] Example 12. The method of example 11, wherein: the second noise sampling scan comprises collecting noise data from a first plurality of non-driven TX channels on the first sub-portion; and the third noise sampling scan comprises collecting the noise data from a second plurality of non-driven TX channels on the second sub-portion.

[0116] Example 13. The method of examples 11-12, wherein: the second noise sampling scan comprises collecting noise data from a first plurality of non-driven TX channels on the first sub-portion; the third noise sampling scan comprises collecting noise data from a single first non-driven TX channel on the second sub-portion.

[0117] Example 14. An apparatus comprising: a display layer comprising a plurality of pixels; a touch sensing layer adjacent to the display layer, the touch sensing layer comprising a plurality of sensors, each sensor associated with one or more of the pixels; a touch controller; and a non-transitory memory storing a program to be executed by the touch controller, the program comprising instructions to: simultaneously perform a mutual sampling scan on a first portion of the display layer and a noise sampling scan on a second portion of the display layer, the second portion being larger than the first portion of the display layer; detect noise values from the second portion of the display layer; compare the noise values to a predetermined frequency value of the touch controller; and adjust the predetermined frequency value when at least one of the noise values exceeds the predetermined frequency value.

[0118] Example 15. The apparatus of example 14, wherein performing the mutual sampling scan comprises driving a first TX channel.

[0119] Example 16. The apparatus of examples 14-15, wherein performing the noise sampling scan comprises collecting the noise values through non-driven TX channels.

[0120] Example 17. The apparatus of examples 14-16, wherein comparing the noise values comprises determining the predetermined frequency value that the touch controller is sampling, and comparing the noise values to the predetermined frequency value of the touch controller.

[0121] Example 18. The device of examples 14-17, further comprising increasing a touch sensitivity of the touch sensing layer.

[0122] Example 19. The device of examples 14-18, wherein adjusting the predetermined frequency value comprises instructing the touch controller to change a first predetermined frequency value to a second predetermined frequency value based on the noise value.

[0123] Example 20. The device of examples 14-19, further comprising performing a subsequent mutual sampling scan based on the second predetermined frequency value.

[0124] While the present disclosure has been described with reference to illustrative embodiments, the description is not intended to be construed in a limiting sense. Various modifications and combinations of the illustrative embodiments, along with other embodiments, will be apparent to persons skilled in the art upon reference to the description. It is therefore intended that the appended claims encompass any such modifications or embodiments.

Claims

1. A method for operating an electronic device, the method comprising: performing concurrently a mutual sampling scan on a first portion of a touchscreen, and a noise sampling scan on a second portion of the touchscreen, the second portion being larger than the first portion of the touchscreen; detecting noise values from the second portion of the touchscreen; comparing the noise values to a predetermined frequency value of a touch controller; and adjusting the predetermined frequency value when at least one of the noise values exceeds the predetermined frequency value.

2. The method of claim 1, further comprising performing concurrently a subsequent mutual sampling scan on the first portion of the touchscreen, and a subsequent noise sampling scan on the second portion of the touchscreen, wherein the first portion of the touchscreen changes with each subsequent mutual sampling scan, and the second portion of the touchscreen changes with each subsequent noise sampling scan.

3. The method of claim 1, wherein performing the mutual sampling scan comprises driving a first TX channel of a plurality of TX channels, and wherein performing the noise sampling scan comprises collecting the noise values through non-driven TX channels of the plurality of TX channels.

4. The method of claim 1, wherein comparing the noise values comprises determining the predetermined frequency value that the touch controller is sampling, and comparing the noise values to the predetermined frequency value of the touch controller.

5. The method of claim 1, further comprising increasing touch sensitivity of the touchscreen.

6. The method of claim 1, wherein adjusting the predetermined frequency value comprises instructing the touch controller to change a first predetermined frequency setting to a second predetermined frequency setting based on the noise values.

7. The method of claim 6, further comprising performing a subsequent mutual sampling scan based on the second predetermined frequency.

8. A method for operating an electronic device, the method comprising: displaying an image on a plurality of portions of a touchscreen, the plurality of portions including a first portion and a second portion, the second portion being larger than the first portion; performing a mutual sampling scan on the first portion of the display by driving a first TX channel during a first time period; performing a first noise sampling scan to collect noise data on the second portion of the display through a plurality of non-driven TX channels during the first time period; determining a first noise frequency from the second portion of the display; and setting a noise frequency threshold based on the first noise frequency.

9. The method of claim 8, further comprising performing a second noise sampling scan on a third portion of the plurality of portions during the first time period, the second noise sampling scan being performed prior to the mutual sampling scan.

10. The method of claim 8, wherein the second portion of the touchscreen includes a first sub-portion and a second sub-portion, the first portion being located between the first sub-portion and the second sub-portion.

11. The method of claim 10, further comprising: performing a second noise sampling scan and a third noise sampling scan during a second time period, wherein the second noise sampling scan includes collecting the noise data from a first non-driven TX channel on the first sub-portion, and wherein the third noise sampling scan includes collecting the noise data from a second non-driven TX channel on the second sub-portion; determining a second noise frequency from the second portion of the touchscreen; comparing the first noise frequency and the second noise frequency; and adjusting the noise frequency threshold when the second noise frequency exceeds the first noise frequency.

12. The method of claim 11, wherein: the second noise sampling scan includes collecting the noise data from a first plurality of non-driven TX channels on the first sub-portion; the third noise sampling scan includes collecting the noise data from a second plurality of non-driven TX channels on the second sub-portion.

13. The method of claim 11, wherein: the second noise sampling scan includes collecting the noise data from a first plurality of non-driven TX channels on the first sub-portion; the third noise sampling scan includes collecting the noise data from a single first non-driven TX channel on the second sub-portion.

14. An apparatus comprising: a display layer including a plurality of pixels; a touch sensing layer adjacent to the display layer, the touch sensing layer including a plurality of sensors, each sensor associated with one or more of the pixels; a touch controller; and a non-transitory memory storing a program to be executed by the touch controller, the program including instructions to perform the steps of: performing a mutual sampling scan on a first portion of the display layer and a noise sampling scan on a second portion of the display layer simultaneously, the second portion greater than the first portion of the display layer; detecting noise values from the second portion of the display layer; comparing the noise values to a predetermined frequency value of the touch controller; and adjusting the predetermined frequency value when at least one of the noise values exceeds the predetermined frequency value.

15. The apparatus of claim 14, wherein performing the mutual sampling scan includes driving a first TX channel.

16. The apparatus of claim 15, wherein performing the noise sampling scan includes collecting the noise values through non-driven TX channels.

17. The apparatus of claim 14, wherein comparing the noise values includes determining the predetermined frequency value that the touch controller is sampling, and comparing the noise values to the predetermined frequency value of the touch controller.

18. The apparatus of claim 14, further comprising increasing touch sensitivity of the touch sensing layer.

19. The apparatus of claim 14, wherein adjusting the predetermined frequency value includes instructing the touch controller to change a first predetermined frequency value to a second predetermined frequency value based on the noise values.

20. The apparatus of claim 19, further comprising performing a subsequent mutual sampling scan based on the second predetermined frequency value.

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