Noise cancellation

Electronic devices, storage medium containing instructions, and methods pertain to cancelling noise that results from application of voltages on gates of transistors in a display. One or more compensation or dummy drivers are used to apply a compensation voltage that is an inversion of voltages applied on the gates of the transistors.

BACKGROUND

The present disclosure relates generally to techniques to cancelling noise resultant from in a display. More specifically, the present disclosure relates generally to techniques for noise cancellation resulting from a gate driver clock and its interference with an overlay touch panel.

Electronic display panels are used in a plethora of electronic devices. These display panels typically consist of multiple pixels that emit light. These pixels may be formed using self-emissive units (e.g., light emitting diode) or pixels that utilize units that are backlit (e.g., liquid crystal diode). These pixels are usually controlled using transistors (e.g., thin film transistors) that utilize a driving threshold voltage to determine at which level the pixels are to be driven. These displays may also include touch functionality that may be interfered with by operation of the display. Specifically, noise from a gate driver clock of the gates of the pixels may pull a voltage of a touch sensing layer up or down in the direction of the clock voltage fluctuation due to capacitive coupling with a substrate on which pixel circuitry is mounted. This voltage fluctuation may result in false positive touches and/or may result in touches occurring without being sensed by the display.

SUMMARY

A gate driver clock may be used to cancel out the voltage fluctuations of the touch layer. As previously noted, these fluctuations may be caused by a gate driver clock driving pixels connected to a substrate. A gate driver clock may be driven at an inverse voltage simultaneously with any connected gate driver clock to reduce the effect of the fluctuation on the touch levels. Moreover, this gate driver clock may be a dummy gate driver clock that is merely connected to the substrate without passing a voltage to any gate for usage. Additionally, in some embodiments, each operating gate driver clock may be at least partially cancelled using a respective dedicated gate driver clock, but in other embodiments, a cancelling gate driver clock may at least partially cancel out one or more other gate driver clock fluctuations.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

As previously discussed, cancelling gate driver clock(s) may be used to cancel out the voltage fluctuations of a touch layer. As previously noted, these fluctuations on the touch layer may be caused by a gate driver clock driving pixels connected to a substrate. A gate driver clock may be driven at an inverse voltage simultaneously with any connected gate driver clock to reduce the effect of the fluctuation on the touch levels. Moreover, this gate driver clock may be a dummy gate driver clock that is merely connected to the substrate without pass a voltage to any gate for usage. Additionally, in some embodiments, each operating gate driver clock may be at least partially cancelled using a respective dedicated gate driver clock, but in other embodiments, a cancelling gate driver clock may at least partially cancel out one or more other gate driver clock fluctuations.

With the foregoing in mind and referring first toFIG. 1, an electronic device10according to an embodiment of the present disclosure may include, among other things, one or more processor(s)12, memory14, nonvolatile storage16, a display18, input structures20, an input/output (I/O) interface22, a power source24, and interface(s)26. The various functional blocks shown inFIG. 1may include hardware elements (e.g., including circuitry), software elements (e.g., including computer code stored on a computer-readable medium) or a combination of both hardware and software elements. It should be noted thatFIG. 1is merely one example of a particular implementation and is intended to illustrate the types of components that may be present in electronic device10.

In the electronic device10ofFIG. 1, the processor(s)12and/or other data processing circuitry may be operably coupled with the memory14and the nonvolatile storage16to perform various algorithms. Such programs or instructions, including those for executing the techniques described herein, executed by the processor(s)12may be stored in any suitable article of manufacture that includes one or more tangible, computer-readable media at least collectively storing the instructions or routines, such as the memory14and the nonvolatile storage16. The memory14and the nonvolatile storage16may include any suitable articles of manufacture for storing data and executable instructions, such as random-access memory, read-only memory, rewritable flash memory, hard drives, and/or optical discs. Also, programs (e.g., an operating system) encoded on such a computer program product may also include instructions that may be executed by the processor(s)12to enable the electronic device10to provide various functionalities.

In certain embodiments, the display18may be a liquid crystal display (e.g., LCD), which may allow users to view images generated on the electronic device10. In some embodiments, the display18may include a touch screen, which may allow users to interact with a user interface of the electronic device10. Furthermore, it should be appreciated that, in some embodiments, the display18may include one or more light emitting diode (e.g., LED) displays, or some combination of LCD panels and LED panels.

The input structures20of the electronic device10may enable a user to interact with the electronic device10(e.g., pressing a button to increase or decrease a volume level, a camera to record video or capture images). The I/O interface22may enable the electronic device10to interface with various other electronic devices. Additionally or alternatively, the I/O interface22may include various types of ports that may be connected to cabling. These ports may include standardized and/or proprietary ports, such as USB, RS232, Apple's Lightning® connector, as well as one or more ports for a conducted RF link.

As further illustrated, the electronic device10may include the power source24. The power source24may include any suitable source of power, such as a rechargeable lithium polymer (e.g., Li-poly) battery and/or an alternating current (e.g., AC) power converter. The power source24may be removable, such as a replaceable battery cell.

The interface(s)26enable the electronic device10to connect to one or more network types. The interface(s)26may also include, for example, interfaces for a personal area network (e.g., PAN), such as a Bluetooth network, for a local area network (e.g., LAN) or wireless local area network (e.g., WLAN), such as an 802.11 Wi-Fi network or an 802.15.4 network, and/or for a wide area network (e.g., WAN), such as a 3rd generation (e.g., 3G) cellular network, 4th generation (e.g., 4G) cellular network, or long term evolution (e.g., LTE) cellular network. The interface(s)26may also include interfaces for, for example, broadband fixed wireless access networks (e.g., WiMAX), mobile broadband Wireless networks (e.g., mobile WiMAX), and so forth.

By way of example, the electronic device10may represent a block diagram of the notebook computer depicted inFIG. 2, the handheld device depicted in either ofFIG. 3orFIG. 4, the desktop computer depicted inFIG. 5, the wearable electronic device depicted inFIG. 6, or similar devices. It should be noted that the processor(s)12and/or other data processing circuitry may be generally referred to herein as “data processing circuitry.” Such data processing circuitry may be embodied wholly or in part as software, firmware, hardware, or any combination thereof. Furthermore, the data processing circuitry may be a single contained processing module or may be incorporated wholly or partially within any of the other elements within the electronic device10.

In certain embodiments, the electronic device10may take the form of a computer, a portable electronic device, a wearable electronic device, or other type of electronic device. Such computers may include computers that are generally portable (e.g., such as laptop, notebook, and tablet computers) as well as computers that are generally used in one place (e.g., such as conventional desktop computers, workstations and/or servers). In certain embodiments, the electronic device10in the form of a computer may be a model of a MacBook®, MacBook® Pro, MacBook Air®, iMac®, Mac® mini, or Mac Pro® available from Apple Inc. By way of example, the electronic device10, taking the form of a notebook computer30A, is illustrated inFIG. 2in accordance with one embodiment of the present disclosure. The depicted computer30A may include a housing or enclosure32, a display18, input structures20, and ports of the I/O interface22. In one embodiment, the input structures20(e.g., such as a keyboard and/or touchpad) may be used to interact with the computer30A, such as to start, control, or operate a GUI or applications running on computer30A. For example, a keyboard and/or touchpad may allow a user to navigate a user interface or application interface displayed on display18.

FIG. 3depicts a front view of a handheld device30B, which represents one embodiment of the electronic device10. The handheld device30B may represent, for example, a portable phone, a media player, a personal data organizer, a handheld game platform, or any combination of such devices. By way of example, the handheld device30B may be a model of an iPod® or iPhone® available from Apple Inc. of Cupertino, Calif.

The handheld device30B may include an enclosure32to protect interior components from physical damage and to shield them from electromagnetic interference. The enclosure32may surround the display18, which may display indicator icons. The indicator icons may indicate, among other things, a cellular signal strength, Bluetooth connection, and/or battery life. The I/O interfaces22may open through the enclosure32and may include, for example, an I/O port for a hard-wired connection for charging and/or content manipulation using a connector and protocol, such as the Lightning connector provided by Apple Inc., a universal serial bus (e.g., USB), one or more conducted RF connectors, or other connectors and protocols.

The illustrated embodiments of the input structures20, in combination with the display18, may allow a user to control the handheld device30B. For example, a first input structure20may activate or deactivate the handheld device30B, one of the input structures20may navigate user interface to a home screen, a user-configurable application screen, and/or activate a voice-recognition feature of the handheld device30B, while other of the input structures20may provide volume control, or may toggle between vibrate and ring modes. Additional input structures20may also include a microphone that may obtain a user's voice for various voice-related features, and a speaker to allow for audio playback and/or certain phone capabilities. The input structures20may also include a headphone input (not illustrated) to provide a connection to external speakers and/or headphones and/or other output structures.

FIG. 4depicts a front view of another handheld device30C, which represents another embodiment of the electronic device10. The handheld device30C may represent, for example, a tablet computer, or one of various portable computing devices. By way of example, the handheld device30C may be a tablet-sized embodiment of the electronic device10, which may be, for example, a model of an iPad® available from Apple Inc. of Cupertino, Calif.

Turning toFIG. 5, a computer30D may represent another embodiment of the electronic device10ofFIG. 1. The computer30D may be any computer, such as a desktop computer, a server, or a notebook computer, but may also be a standalone media player or video gaming machine. By way of example, the computer30D may be an iMac®, a MacBook®, or other similar device by Apple Inc. It should be noted that the computer30D may also represent a personal computer (e.g., PC) by another manufacturer. A similar enclosure32may be provided to protect and enclose internal components of the computer30D such as the dual-layer display18. In certain embodiments, a user of the computer30D may interact with the computer30D using various peripheral input devices, such as the keyboard37or mouse38, which may connect to the computer30D via an I/O interface22.

Similarly,FIG. 6depicts a wearable electronic device30E representing another embodiment of the electronic device10ofFIG. 1that may be configured to operate using the techniques described herein. By way of example, the wearable electronic device30E, which may include a wristband43, may be an Apple Watch® by Apple, Inc. However, in other embodiments, the wearable electronic device30E may include any wearable electronic device such as, for example, a wearable exercise monitoring device (e.g., pedometer, accelerometer, heart rate monitor), or other device by another manufacturer. The display18of the wearable electronic device30E may include a touch screen (e.g., LCD, an organic light emitting diode display, an active-matrix organic light emitting diode (e.g., AMOLED) display, and so forth), which may allow users to interact with a user interface of the wearable electronic device30E.

FIG. 7illustrates a portion of unit pixel circuitry50. The unit pixel circuitry50includes a control transistor52that controls emission levels of a light emitting diode (LED)54. For example, the transistor52may include a thin film transistor (TFT). A gate of the transistor52may be driven using a gate driver clock. However, this gate driver clock may result in voltage fluctuations of a touch layer of the display.

FIG. 8illustrates a cross-sectional view of a portion60of the display18. The portion60includes a substrate62upon which pixel circuitry64is mounted within an active area66of the display18. For example, the pixel circuitry64may include thin-film transistors (TFTs). The pixel circuitry64is driven using two single-phase gate driver clocks68and70to drive gates in the active area and/or outside the active area. The portion60also includes one or more planarization layers72and74that are made of insulative material, such as a nitride or an oxide. An anode electrode76and a cathode electrode78may be used to carry current in and out of the active area for display and/or touch functionality. The portion60may also include one or more insulative layers80,82, and84separating a touch layer/electrode86from the cathode78. When the touch electrode86voltage fluctuates, a scan driver circuit detects such fluctuations and attributes touches exceeding a threshold to a touch of the display18.

However, the voltage of the touch electrode86may fluctuate without a touch of the display. Instead, the voltage may fluctuate due to voltage changes at the cathode78due to capacitive coupling between touch electrode86and the cathode78through the insulative layers80,82, and84. Similarly, capacitive coupling may occur between the cathode78and the substrate82though the planarization layer72.FIG. 9illustrates a schematic view of these capacitive couplings. As illustrated, a capacitive coupling92may occur between the touch electrode86and the cathode78. Similarly, capacitive coupling94may occur between the cathode78and the substrate82at the gate driver clock68, and another capacitive coupling96may occur between the cathode78and the substrate82at the gate driver clock70.

These couplings cause the voltage at the touch electrode86to vary when the gate driver clock68and/or the gate driver clock70fluctuate.FIG. 10illustrates an embodiment of a timing diagram100illustrating this relationship. The timing diagram100illustrates a signal102indicative of the voltage at the gate driver clock68(GCK1) and a signal104indicative of the voltage at the gate driver clock70(GCK2). The timing diagram100also illustrates a signal106indicative of a touch electrode voltage. In the illustrated timing diagram100, no actual touch has occurred. However, the signal106spikes upwardly with each rising edge108of GCK1102and GCK2104. If this spike exceeds a threshold for detecting a touch, this spike may register as a false positive. Moreover, the signal106also spikes downwardly with each falling edge110of the GCK1102and GCK2104. If this downward spike occurs at the time of an actual touch, the touch may not register as a touch due to the downward spike pushing the signal106down below the threshold for touch sensing detection.

To address these voltage fluctuations, cancelling signals (e.g., from gate driver clocks) may be injected into the substrate at opposite polarity with similar amplitude and frequency to at least partially cancel the causes of the voltage fluctuations illustrated inFIG. 9.

FIG. 11illustrates a process for at least partially cancelling noise in a display with touch sensing. The processor12and/or timing circuitry in the display18determines that a voltage is to be applied to gates of transistors of the display (block114). The processor12and/or the timing circuitry cause inverse signals to be generated and injected into the substrate to at least partially cancel voltage fluctuations that would be caused by the gate driver clock (block116). These inverse signals may include signals that are not proactively used to control other circuitry. Instead, in such embodiments, these inverse signals may be a “dummy” or “compensation” gate driver clock that generates an inverted clock signal to cancel out such effects. Additionally or alternatively, these inverse clock signals may be used to switch other circuitry such as gates of adjacent pixels. These inverse signals may be used in a polarity switching timing scheme and/or to control gates in depletion mode.

FIG. 12illustrates a portion120of the display18that is similar to the portion60. However, the portion120includes a single cancelling signal generator—cancelling gate driver clock122—that injects an inverse signal of what is being injected in to the substrate82by the gate driver clocks68and70.FIG. 13illustrates the capacitive coupling124of the touch electrode86, the cathode88, and the gate driver clocks68,70, and122. Specifically, this coupling124is similar to the coupling90shown inFIG. 9except that an additional coupling126exists in the coupling124.

FIG. 14illustrates an embodiment of a timing diagram130illustrating a relationship between the gate driver clocks and a touch electrode voltage utilizing voltage fluctuation compensation. The timing diagram130illustrates a signal132indicative of the voltage at the gate driver clock68(GCK1) and a signal134indicative of the voltage at the gate driver clock70(GCK2). The timing diagram130also illustrates a signal136indicative of the voltage at the dummy gate driver clock122(GCKB) and a signal138indicative of a touch electrode voltage. In some embodiments, the GCKB122signal may be generated by performing a logical AND on GCK1signal132and GCK2signal134and inverting (either before ANDing or after ANDing).

In the illustrated timing diagram130, no actual touch has occurred, but the signal138increases upwardly with each rising edge140of the of GCK1132and GCK2134. However, this increase is relatively lower than the spike in the timing diagram100ofFIG. 10due to the inclusion of the voltage on the display via GCKB138. Moreover, decreases in the signal106with each falling edge142of the GCK1132and GCK2134may also be relatively lower due to inverse application of voltages on the GCKB138. In other words, the increase/decrease in voltage due to GCK1132and/or GCK2134switching may be partially or completely reduced. This reduced magnitude of fluctuation on the touch electrode may reduce the likelihood of a false positive of a touch event.

FIG. 15illustrates a portion150of the display18that is similar to the portion130. However, the portion120includes an additional cancelling signal generator—gate clock driver152—in addition to the cancelling signal generator—gate clock driver122—that injects an inverse signal of what is being injected in to the substrate82by the gate driver clocks68and70. In the illustrated embodiment, a noise cancelling signal generator may be used for individual gate clocks. In other words, the cancelling signal generator may at least partially cancel noise arising from operation of the gate driver clock68while the additional cancelling signal generator at least partially cancels noise arising from operation of the gate driver clock70. The timing of each cancelling gate drivers122and152may be a simple inversion of a corresponding gate driver clock. However, inclusion of additional gate drivers (e.g., cancelling signal generator) may increase a size of compensation circuitry in the display causing the display size to potentially increase without increasing viewable space and/or increasing complication of routing in the display. Some embodiments may use a combination of dedicated signal cancellation and individual cancellation by using more than a single noise cancellation driver, but using at least one of those noise cancellation circuitries to at least partially cancel noise arising from more than one single gate driver clock.

FIG. 16illustrates the capacitive coupling154of the touch electrode86, the cathode88, and the gate driver clocks68,70,122, and152. Specifically, this coupling154is similar to the coupling124shown inFIG. 13except that an additional coupling156exists in the coupling154due to the additional gate driver clock152.

FIG. 17illustrates a timing diagram160that is similar to the timing diagram130ofFIG. 14. However, as noted,FIG. 17utilizes two dummy gate driver clocks to compensate for noise generated by other gate driver clocks. The timing diagram160illustrates a relationship between the gate driver clocks and a touch electrode voltage utilizing voltage fluctuation compensation. The timing diagram160illustrates a signal162indicative of the voltage at the gate driver clock68(GCK1) and a signal164indicative of the voltage at the gate driver clock70(GCK2). The timing diagram130also illustrates a signal166indicative of the voltage at the dummy gate driver clock122(GCK1B), a signal168indicative of the voltage at the dummy gate driver clock152(GCK2B), and a signal170indicative of a touch electrode voltage. In the illustrated timing diagram160, no actual touch has occurred, but the signal170increases upwardly with each rising edge172of the of GCK1162and GCK2164. However, this increase is relatively lower than the spike in the timing diagram100ofFIG. 10due to the inclusion of the dummy gate driver clocks122and152applying voltages GCK1B166and GCK2B168. Moreover, decreases in the signal170with each falling edge174of the GCK1162and GCK2264are also relatively lower due to inverse application of voltages on the GCK1B166and GCK2B168. This reduced magnitude of fluctuation on the touch electrode may reduce the likelihood of a false positive of a touch event. In some embodiments, the fluctuations may be reduced entirely.

It is worth noting that using a dedicated compensating dummy gate driver clock for each gate driver clock may simplify driving of the dummy gate driver clocks and/or assure that all gate driver clocks can be compensated for. However, using dedicated dummy gate driver clocks to compensate for each gate driver clock may use more space and/or complicate routing on the display. Thus, these two embodiments may be balanced based on design needs. Furthermore, these embodiments may be combined to include some dummy gate driver clocks driving compensating for two or more gate driver clocks while one or more dummy gate driver clocks compensate for one specific gate driver clock.