PATENT DOCUMENT

Publication Number: US-10636362-B2
Application Number: US-201816048217-A
Country: US
Kind Code: B2

Title: Radio frequency signal emission induced display artifact mitigation systems and methods

Abstract:
Display artifacts, such as muras, may be perceptible on an electronic display when an electronic device includes a radio frequency transceiver that outputs electromagnetic waves during an emission period and a display panel that writes to display pixels during a refresh period. The electronic device may also include a controller that is coupled to the radio frequency transceiver and the display panel and facilitates the reduction and/or elimination of overlap between the emission periods and the refresh periods to decrease the appearance of display artifacts. In particular, the controller may execute instructions to determine the duration of the emission period and determine the duration of the blanking period that occurs between the refresh periods. Further, based on the determined blanking period and emission period durations, the controller may instruct the radio frequency transceiver to adjust the timing of the first emission period, instruct the display panel to adjust the timing of the refresh rate, or both to reduce overlap.

Claims:
What is claimed is: 
     
       1. An electronic device comprising:
 a radio frequency transceiver configured to output first electromagnetic waves during a first emission period; 
 a display panel comprising a plurality of display pixels, wherein the display panel is configured to display at least a first portion of a first image by writing to at least some of the plurality of display pixels during a first refresh period; and 
 a controller communicatively coupled to the radio frequency transceiver and the display panel, wherein the controller is programmed to:
 determine a first target duration of the first emission period; 
 determine a first duration of a blanking period that occurs between the first refresh period and a second refresh period when the display panel implements a first refresh rate; and 
 instruct the radio frequency transceiver to adjust timing of the first emission period, instruct the display panel to adjust refresh rate from the first refresh rate, or both based at least in part on the first target duration of the first emission period and the first duration of the blanking period to facilitate reducing amount of overlap between the first emission period and the first refresh period. 
 
 
     
     
       2. The electronic device of  claim 1 , wherein the radio frequency transceiver is a near-field communication module operating in an active reader mode. 
     
     
       3. The electronic device of  claim 1 , wherein the controller is programmed to:
 determine whether the first target duration of the first emission period is greater than the first duration of the blanking period; and 
 when the first target duration of the first emission period is not greater than the first duration of the blanking period:
 instruct the display panel to display the first image using the first refresh rate; 
 determine a first target timing of the first emission period that occurs during the blanking period; and 
 instruct the radio frequency transceiver to output the first electromagnetic waves during the first emission period based at least in part on the first target duration and the first target timing of the first emission period. 
 
 
     
     
       4. The electronic device of  claim 1 , wherein the controller is programmed to:
 determine a second duration of the blanking period that occurs between the first refresh period and the second refresh period when the display panel implements a second refresh rate lower than the first refresh rate; and 
 when the first target duration of the first emission period is greater than the first duration of the blanking period:
 determine whether the first target duration of the first emission period is greater than the second duration of the blanking period; and 
 instruct the display panel to display the first image using the second refresh rate when the first target duration of the first emission period is not greater than the second duration of the blanking period. 
 
 
     
     
       5. The electronic device of  claim 4 , comprising an image source communicatively coupled to the controller, wherein:
 the image source is configured to generate image data that indicates target luminance of the plurality of display pixels; and 
 the controller is programmed to instruct the image source to generate image data corresponding with a black image when the first target duration of the first emission period is greater than the second duration of the blanking period. 
 
     
     
       6. The electronic device of  claim 4 , wherein the controller is programmed to:
 determine a third duration of the blanking period that occurs between the first refresh period and the second refresh period when the display panel implements a third refresh rate lower than the second refresh rate; and 
 when the first target duration of the first emission period is greater than the third duration of the blanking period:
 determine whether the first target duration of the first emission period is greater than the third duration of the blanking period; and 
 instruct the display panel to display the first image using the third refresh rate when the first target duration of the first emission period is not greater than the third duration of the blanking period. 
 
 
     
     
       7. The electronic device of  claim 1 , wherein the electronic device comprises: a display system comprising: the radio frequency transceiver configured to output the first electromagnetic waves during the first emission period; the display panel comprising the plurality of display pixels, wherein the display panel is configured to: generate a first synchronization signal based at least in part on activity of the display panel; and supply the first synchronization signal to the radio frequency transceiver, the display system, or both; and the controller communicatively coupled to the radio frequency transceiver and the display panel, wherein the controller is programmed to: generate a second synchronization signal based at least in part on activity of the display panel and activity of the radio frequency transceiver; and supply the second synchronization signal to the display panel, the radio frequency transceiver, or both. 
     
     
       8. The electronic device of  claim 1 , wherein:
 the controller is programmed to generate a synchronization signal supplied to the radio frequency transceiver and the display panel; 
 the display panel is configured to write each of the plurality of display pixels while the synchronization signal is in a first state; and 
 the radio frequency transceiver is configured to output electromagnetic waves while the synchronization signal is in a second state. 
 
     
     
       9. The electronic device of  claim 1 , wherein:
 the display panel is configured to generate a synchronization signal to the radio frequency transceiver, wherein the display panel and the radio frequency transceiver are configured to utilize time division multiplexing (TDM) based on the synchronization signal; 
 the display panel is configured to write each of the plurality of display pixels while the synchronization signal is in a first state of the time division multiplexing; and 
 the radio frequency transceiver is configured to output electromagnetic waves while the synchronization signal is in a second state of the time division multiplexing. 
 
     
     
       10. The electronic device of  claim 1 , wherein:
 the radio frequency transceiver is configured to generate a synchronization signal to the display panel, wherein the radio frequency transceiver and the display panel are configured to utilize time division multiplexing (TDM) based on the synchronization signal; 
 the radio frequency transceiver is configured to write each of the plurality of display pixels while the synchronization signal is in a first state of the time division multiplexing; and 
 the display panel is configured to output electromagnetic waves while the synchronization signal is in a second state of the time division multiplexing. 
 
     
     
       11. The electronic device of  claim 1 , wherein:
 the display panel is configured to write the first image to the plurality of display pixels while a tearing effect signal is high; and 
 the radio frequency transceiver is configured to:
 receive the tearing effect signal; and 
 output the first electromagnetic waves while the tearing effect signal is low. 
 
 
     
     
       12. The electronic device of  claim 1 , wherein the radio frequency transceiver is configured to:
 output the first electromagnetic waves during the first emission period to facilitate detecting presence of an object located within a threshold distance from the electronic device; 
 output second electromagnetic waves during a second emission period after the first emission period when the presence of the object is detected via the first electromagnetic waves to facilitate determining whether the object comprises a radio frequency transceiver device, wherein duration of the second emission period is greater than the first emission period; and 
 output third electromagnetic waves during a third emission period after the second emission period when the radio frequency transceiver device is detected to facilitate supplying electrical energy from the electronic device to the radio frequency transceiver device that enables the radio frequency transceiver device to wirelessly transmit data back to the electronic device. 
 
     
     
       13. The electronic device of  claim 1 , wherein, to determine the first target duration of the first emission period, the controller is programmed to:
 determine an operational mode of the radio frequency transceiver; and 
 determine the first target duration of the first emission period based at least in part on the operational mode of the radio frequency transceiver. 
 
     
     
       14. The electronic device of  claim 13 , wherein the operational mode comprises an active reader mode, and wherein the controller is programmed to:
 determine that the first target duration of the first emission period is a first value when the radio frequency transceiver is operating in an object-detection sub-mode of the active reader mode; 
 determine that the first target duration of the first emission period is a second value greater than the first value when the radio frequency transceiver is operating in a polling sub-mode of the active reader mode; and 
 determine that the first target duration of the first emission period is a third value greater than the second value when the radio frequency transceiver is operating in a reading sub-mode of the active reader mode. 
 
     
     
       15. The electronic device of  claim 1 , wherein, while operating in a passive tag mode, the radio frequency transceiver is configured to:
 receive electrical energy via second electromagnetic waves output from an active radio frequency transceiver device; and 
 operate using the electrical energy received from the active radio frequency transceiver device to wirelessly communicate data back to the active radio frequency transceiver device by outputting third electromagnetic waves modulated based at least in part on an analog electrical signal that indicates the data. 
 
     
     
       16. The electronic device of  claim 1 , wherein the electronic device comprises a portable phone, a media player, a personal data organizer, a handheld game platform, a tablet device, a computer, or any combination thereof. 
     
     
       17. A method for controlling operation of an electronic device implemented with a near-field communication module and an electronic display, comprising:
 determining, using a controller, an operational mode of the near-field communication module; 
 determining, using the controller, a target duration of an electromagnetic wave emission period based at least in part on the operational mode of the near-field communication module; 
 determining, using the controller, a target refresh rate to be implemented by the electronic display based at least in part on the target duration of the electromagnetic wave emission period; 
 determining, using the controller, timing of blanking periods that each occur between successive refresh periods when the electronic display implements the target refresh rate; and 
 instructing, using the controller, the near-field communication module to output electromagnetic waves only during emission periods that each occurs during the blanking periods. 
 
     
     
       18. The method of  claim 17 , wherein determining the target duration of the electromagnetic wave emission period comprises:
 determining that the target duration of the electromagnetic wave emission period is a first duration when the near-field communication module is in a first operational mode during which the near-field communication module outputs electromagnetic waves to facilitate detecting presence of an object located within a threshold distance from the electronic device; 
 determining that the target duration of the electromagnetic wave emission period is a second duration greater than the first duration when the near-field communication module is in a second operational mode during which the near-field communication module outputs electromagnetic waves to facilitate detecting whether the object is another near-field communication device; and 
 determining that the target duration of the electromagnetic wave emission period is a third duration greater than the second duration when the near-field communication module is in a third operational mode during which the near-field communication module outputs electromagnetic waves to facilitate supplying electrical energy that the other near-field communication device uses to power wireless transmission of data back to the electronic device. 
 
     
     
       19. The method of  claim 17 , wherein determining the target refresh rate comprises:
 determining that the target refresh rate is a first refresh rate when the near-field communication module is in operating in an object-detection mode; and 
 determining that the target refresh rate is a second refresh rate greater than the first refresh rate when the near-field communication module is in operating in a polling mode or a reading mode. 
 
     
     
       20. The method of  claim 17 , wherein determining the target refresh rate comprises:
 determining that the blanking periods each have a first duration when the electronic display implements a first candidate refresh rate; 
 indicating the first candidate refresh rate as the target refresh rate when the first duration of the blanking periods is greater than the target duration of the electromagnetic wave emission period; and 
 indicating a second candidate refresh rate lower than the first candidate refresh rate as the target refresh rate when the first duration of the blanking periods is not greater than the target duration of the electromagnetic wave emission period. 
 
     
     
       21. The method of  claim 20 , comprising:
 determining, using the controller, that the blanking periods each have a second duration when the electronic display implements the second candidate refresh rate; and 
 instructing, using the controller, an image source to output image data corresponding with a black image when the second duration of the blanking periods is not greater than the target duration of the electromagnetic wave emission period. 
 
     
     
       22. A tangible, non-transitory, computer-readable medium that stores instructions executable by one or more processors of an electronic device, wherein the instructions comprise instructions to:
 instruct, using the one or more processors, the electronic device to generate a tearing effect signal; 
 instruct, using the one or more processors, the electronic device to supply the tearing effect signal to an electronic display to enable the electronic display to control refresh timing by refreshing only while the tearing effect signal is in a first state; and 
 instruct, using the one or more processors, the electronic device to supply the tearing effect signal to a near-field communication device located within a threshold distance from the electronic display to enable the near-field communication device to control emission timing by outputting electromagnetic waves only while the tearing effect signal is in a second state. 
 
     
     
       23. The tangible, non-transitory, computer-readable medium of  claim 22 , wherein the instructions to instruct the electronic device to generate the tearing effect signal comprise instructions to:
 determine a target refresh rate to be implemented by the electronic display; and 
 instruct the electronic display to generate the tearing effect signal based at least in part on the target refresh rate, line time implemented in the electronic display, resolution of the electronic display, or any combination thereof. 
 
     
     
       24. The tangible, non-transitory, computer-readable medium of  claim 23 , wherein the instructions to determine the target refresh rate comprise instructions to:
 determine an operational mode of the near-field communication device; and 
 determine the target refresh rate to be implemented by the electronic display based at least in part on the operational mode of the near-field communication device. 
 
     
     
       25. The tangible, non-transitory, computer-readable medium of  claim 23 , wherein the instructions to determine the target refresh rate comprise instructions to:
 determine target duration of an emission period during which the near-field communication device continuously outputs electromagnetic waves; and 
 determine the target refresh rate based at least in part on the target duration of the emission period and blanking duration that occurs between successive refresh periods when the electronic display implements the target refresh rate.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 62/655,037, entitled “Radio Frequency Signal Emission Induced Display Artifact Mitigation Systems and Methods,” filed Apr. 9, 2018, which is incorporated herein by reference in its entirety for all purposes. 
    
    
     BACKGROUND 
     The present disclosure relates generally to interactions between radio frequency signals, such as near-field communication (NFC) waves, and an electronic display. More particularly, the present disclosure relates generally to reducing perceivability of display artifacts (e.g., muras) that may arise due to interactions between the radio frequency signal and display pixels of an electronic display. 
     This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art. 
     Electronic devices often use one or more electronic displays to present visual representations of information (e.g., text, still images, video) based on corresponding image content. For example, such electronic devices may include computers, mobile phones, portable media devices, virtual-reality headsets, and vehicle dashboards, among many others. In any case, to display an image, an electronic display may control light emission (e.g., luminance) of its display pixels based at least in part on corresponding image data. Additionally, in some instances, luminance of a display pixel may vary based at least in part on electrical energy stored in the display pixel. Thus, to control light emission from a display pixel, the electronic display may supply a data (e.g., analog electrical) signal to the display pixel based at least in part on corresponding image data and instruct the display pixel to store electrical energy based at least in part on the data signal, thereby writing (e.g., refreshing) the display pixel. 
     Electronic devices may also often include radio frequency transceivers that may output a radio frequency signal to another device. For example, a near-field communication (NFC) module (e.g., device) may facilitate communication with other NFC devices, such as a passive NFC tag and/or an active NFC reader. When operating as an active NFC reader, the NFC module may enable contactless communication between a corresponding electronic device and a passive NFC tag. To facilitate reducing implementation associated cost, passive NFC tags often do not operate using a dedicated power source (e.g., battery). Instead, a passive NFC tag may operate using electrical energy received via electromagnetic (e.g., NFC) waves, for example, wirelessly transmitted from an active NFC reader. However, the electromagnetic waves may affect the image data signal and/or electrical energy stored in one or more display pixels (e.g., charge stored on a storage capacitor during refreshing of display pixels) and, thus, resulting luminance, which, at least in some instances, may be perceivable as a visual artifact. 
     SUMMARY 
     A summary of certain embodiments disclosed herein is set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of these certain embodiments and that these aspects are not intended to limit the scope of this disclosure. Indeed, this disclosure may encompass a variety of aspects that may not be set forth below. 
     The present disclosure generally relates to mitigating display artifacts arising from interactions between radio frequency signals, such as near-field communication (NFC) electromagnetic waves, and an electronic display by controlling the emission of the radio frequency signals relative to refresh periods of the electronic display. In one example, an NFC module (e.g., device) within a device may be used by the device for contactless communication at short distances with another NFC device (e.g., tag). In some instances, overlap between an emission period of the NFC electromagnetic waves and a refresh period of the electronic display may result in perceivable artifacts, such as muras, for example, due to the NFC electromagnetic waves&#39; effect on electrical energy stored in one or more display pixels and, thus, perceived luminance. 
     To facilitate improving perceived image quality, in some embodiments, timing of the emission period of NFC electromagnetic waves and/or timing of the refresh period may be adjusted to reduce likelihood of the NFC electromagnetic waves affecting perceived luminance of the display pixels. For example, timing of the emission periods for the NFC electromagnetic waves may be adjusted to facilitate reducing amount of overlap between the emission periods and the electronic display refresh periods. Additionally or alternatively, refresh rate of the electronic display may be adjusted (e.g., reduced) to facilitate reducing amount of overlap by adjusting (e.g., increasing) duration of a blanking period that occurs between refresh periods of the electronic display. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various aspects of this disclosure may be better understood upon reading the following detailed description and upon reference to the drawings in which: 
         FIG. 1  is a block diagram of an electronic device, in accordance with an embodiment; 
         FIG. 2  is an example of the electronic device of  FIG. 1  in the form of a handheld device, in accordance with an embodiment; 
         FIG. 3  is another example of the electronic device of  FIG. 1  in the form of a tablet device, in accordance with an embodiment; 
         FIG. 4  is another example of the electronic device of  FIG. 1  in the form of a notebook computer, in accordance with an embodiment; 
         FIG. 5  is another example of the electronic device of  FIG. 1  in the form of a smart watch, in accordance with an embodiment; 
         FIG. 6  is a block diagram of a portion of the electronic device of  FIG. 1  including an electronic display and a near-field communication (NFC) module, in accordance with an embodiment; 
         FIG. 7  is a flow diagram of a process for operating the electronic display and the NFC module of  FIG. 6 , in accordance with an embodiment; 
         FIG. 8  is a timing diagram that describes an operation of the electronic display and the NFC module of  FIG. 6  while the NFC module is operating in an object-detection mode, in accordance with an embodiment; 
         FIG. 9  is a timing diagram that describes an operation of the electronic display and the NFC module of  FIG. 6  while the NFC module is operating in a polling mode, in accordance with an embodiment; 
         FIG. 10  is a timing diagram that describes an operation of the electronic display and the NFC module of  FIG. 6  while the NFC module is operating in a read-detection mode, in accordance with an embodiment; 
         FIG. 11  is a flow diagram of a process for determining a display refresh period to be implemented by the electronic display of  FIG. 6 , in accordance with an embodiment; and 
         FIG. 12  is a flow diagram of a process for determining NFC electromagnetic wave parameters to be implemented by the NFC module of  FIG. 6 , in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS 
     One or more specific embodiments will be described below. In an effort to provide a concise description of these embodiments, not all features of an actual implementation are described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers&#39; specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure. 
     When introducing elements of various embodiments of the present disclosure, the articles “a,” “an,” and “the” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Additionally, it should be understood that references to “one embodiment” or “an embodiment” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. 
     The present disclosure generally relates to radio frequency signals, such as near-field communication (NFC) signals, and electronic displays, which may be implemented to present visual representations of information, for example, in one or more image frames. Generally, an electronic display may display an image by controlling light emission and, thus, perceived (e.g., actual) luminance of its display pixel based at least in part on corresponding image data. In some electronic displays, light emission from a display pixel may vary based at least in part on electrical energy stored in the display pixel. For example, in a liquid crystal display (LCD), electrical energy may be stored in the pixel electrode of a display pixel to produce an electric field between the pixel electrode and a common electrode, which controls orientation of liquid crystals and, thus, light emission from the display pixel. Additionally, in an organic light-emitting diode (OLED) display, electrical energy may be stored in a storage capacitor of a display pixel to control electrical power (e.g., current) supplied to a self-emissive component (e.g., OLED) and, thus, light emission from the display pixel. 
     In some instances, image data may digitally indicate target luminance of display pixels for displaying an image on an electronic display. Since based on stored electrical energy, the electronic display may write a display pixel by supplying an analog electrical (e.g., data) signal based at least in part on corresponding image data to the display pixel and instructing the display pixel to adjust electrical energy stored in its storage component (e.g., pixel electrode or storage capacitor) based at least in part the analog electrical signal. For example, to write an LCD display pixel, a data driver may output a data (e.g., source) signal and a scan driver may output a scan (e.g., gate) signal, which instructs the display pixel to supply the data signal to its pixel electrode. Additionally, to write an OLED display pixel, a data driver may output a data signal and a scan driver may output a scan control signal, which instructs the display pixel to supply the data signal to its storage capacitor. 
     Additionally, a radio frequency (RF) communication device, such as a near-field communication (NFC) module or RF transceiver may be implemented in an electronic device to enable the electronic device to wirelessly communicate with another electronic device. Examples include standalone near-field communication (NFC) devices and/or another near-field communication module implemented in another electronic device, but could also include radio frequency identification (RFID) tags. Generally, near-field communication devices may wirelessly communicate data (e.g., information) via electromagnetic (e.g., radio frequency) waves. To facilitate wirelessly communicating data, a near-field communication device may include an antenna. For example, to facilitate wirelessly transmitting data, the antenna may output electromagnetic waves with amplitude, phase, and/or frequency of the electromagnetic wave modulated based at least in part on an analog electrical signal that indicates the data. On the other hand, to facilitate receiving wirelessly transmitted data, the antenna may output an analog electrical signal generated based at least in part on electromagnetic waves modulated to indicate the data. 
     In some instances, a near-field communication device may be implemented to operate as a passive NFC tag, an active NFC reader, or selectively in either a passive NFC tag mode or an active NFC reader mode. To facilitate reducing implementation associated cost (e.g., component count and/or physical footprint), in some instances, a passive NFC tag may be implemented with a limited power source, for example, compared to an active NFC reader. As such, to enable wirelessly transmitting data, a passive NFC tag may be paired with an active NFC reader that supplies it electrical energy. 
     In some instances, an active NFC reader (e.g., NFC module operating in an active NFC reader mode) may supply electrical energy to a passive NFC tag (e.g., NFC module operating in a passive NFC tag mode) via electromagnetic (e.g., radio frequency) waves. In particular, electromagnetic waves may induce voltage and/or current in an antenna of the passive NFC tag, thereby enabling the antenna to output electrical power that may be stored in the passive NFC tag (e.g., via an inductor and/or a capacitor) as electrical energy and, thus, used to power subsequent operation of the passive NFC tag. For example, the passive NFC tag may utilize the electrical energy to power wireless transmission of data back to the active NFC reader, determination of additional (e.g., measurement and/or sensor) data, storage of the data in memory, and/or retrieval of the data from memory. 
     However, at least in some instances, electromagnetic waves may affect amount of electrical energy stored in one or more display pixels of an electronic display and, thus, actual luminance. For example, when a display pixel is being written (e.g., refreshed), electromagnetic waves may induce voltage and/or current in a conductor coupled to the display pixel, thereby affecting a data signal supplied to the display pixel and, thus, stored electrical energy. The effect on stored electrical energy and, thus, actual luminance may vary based at least in part on strength of the electromagnetic waves interacting with the conductor. Since strength generally decreases inversely proportional with distance squared, to enable sufficiently powering a passive NFC tag, an active NFC reader may output strong electromagnetic waves, for example, relative to other electromagnetic waves that typically interact with the conductor. As such, when implemented with both an active NFC reader (e.g., NFC module operating in an active NFC reader mode) and an electronic display, the strength of electromagnetic waves that interact with conductors in the electronic display may be high, thereby increasing likelihood of a perceivable visual artifact (e.g., mura) occurring, for example, due to actual luminance of one or more display pixels perceivably differing from its target luminance indicated by corresponding image data. While this discussion has generally referred to NFC as an example, radio frequency signals from other radio frequency transceivers in the electronic device may also produce display artifacts on the electronic display if the radio frequency signals are strong enough. 
     As such, the present disclosure provides techniques to facilitate improving perceived image quality provided by an electronic device implemented with a radio frequency transceiver (e.g., as found in an NFC module) and an electronic display. For example, controlling (e.g., adjusting) emission periods of the radio frequency transceiver (e.g., NFC module) and/or refresh periods of the electronic display, few or no radio frequency signals may be emitted while the electronic display is actively writing data to its pixels (e.g., during a display refresh period). This may reduce or prevent the pixels of the electronic display from being changed by strong radio frequency signals. To facilitate improving perceived image quality, in some embodiments, a controller (e.g., NFC controller and/or timing controller) may control parameters (e.g., timing and/or duration) of the NFC module emission periods and/or parameters of the electronic display refresh periods to reduce amount of overlap between the emission periods and the refresh periods. For example, the controller may adjust timing and/or duration of the NFC module emission periods such that emission periods occur during blanking periods (e.g., vertical blanking periods and/or horizontal blanking periods) between electronic display refresh periods. Additionally or alternatively, the controller may adjust timing and/or duration of the electronic display refresh periods such that blanking periods between refresh periods occur during NFC module emission periods, for example, by adjusting refresh rate of the electronic display. 
     Moreover, in some embodiments, parameters of the NFC module emission periods and/or parameters of the electronic display refresh periods may be adjusted based at least in part on an operational mode of the NFC module. For example, when operating in an object-detection mode (e.g., sub-mode of active NFC reader mode), the NFC module may emit short bursts (e.g., 100 μs) of electromagnetic waves to facilitate detecting presence of objects within a threshold distance from the electronic device. In some embodiments, duration of the emission periods while in the object-detection mode may be shorter than other operational modes, for example, such that the emission periods have shorter duration than blanking periods resulting from the electronic display implementing a first (e.g., 60 Hz or maximum) refresh rate. As such, in some embodiments, the controller may control timing of the NFC module emission periods such that each occurs during a blanking period, for example, while maintaining the electronic display at the first refresh rate. 
     In some embodiments, an electronic display may refresh based on a synchronization (e.g., control) signal, such as a tearing effect (TE) signal or a vertical synchronization (V-synch) signal. For example, the electronic display may refresh (e.g., write) its display pixels when the tearing effect signal is high. As such, in some embodiments, the controller may control timing and/or duration of the NFC module emission periods based at least in part on the timing signal. For example, the controller may control timing and/or duration of the NFC module emission periods such that each occurs when the tearing effect signal is low. In some instances, the synchronization signal may be generated by the electronic display and directly sent to the radio frequency transmitter (e.g., NFC module). In other instances, the synchronization signal may be generated by the NFC module and directly sent to the electronic display. The synchronization signal may also be transmitted by the controller to the electronic display and/or NFC module. 
     In any case, when operating in a polling mode (e.g., sub-mode of active NFC reader mode), the NFC module may emit medium bursts (e.g., 40 ms) of electromagnetic waves to facilitate determining whether a detected object is an NFC device. In some embodiments, duration of the emissions periods while in the polling mode may be longer than the object-detection mode, for example, such that the emission periods have longer duration than blanking periods resulting from the electronic display implementing the first (e.g., 60 Hz or maximum) refresh rate. As such, in some embodiments, the controller may control the refresh rate of the electronic display such that each NFC module emission period occurs during a blanking period, for example, by lowering the refresh rate from the first refresh rate to a second (e.g., 10 Hz or intermediate) refresh rate that results in blanking periods with durations greater than the emission periods. 
     Furthermore, when operating in a reading mode (e.g., sub-mode of active NFC reader mode), the NFC module may emit long bursts (e.g., 100 ms or greater) of electromagnetic waves to facilitate supplying the NFC device with sufficient electrical energy to wirelessly transmit data back to the NFC module. In some embodiments, duration of the emissions periods while in the reading mode may be longer than the polling mode, for example, such that the emission periods have longer duration than blanking periods resulting from the electronic display implementing the second refresh rate. When refresh rate can further be reduced, in some embodiments, the controller may control the refresh rate of the electronic display such that each NFC module emission period occurs during a blanking period, for example, by lowering the refresh rate from the second refresh rate to a third (e.g., 1 Hz or minimum) refresh rate that results in blanking periods with duration greater than the emission periods. 
     Additionally or alternatively, image content may be adjusted to facilitate reducing likelihood of perceivable visual artifacts resulting on the electronic display. For example, when duration of NFC module emission periods in the reading mode is greater than duration of blanking periods resulting from the electronic display implementing its minimum (e.g., 1 Hz) refresh rate, the electronic display may be provided with image data corresponding with a black screen while the NFC module is operating in the reading mode. In other words, in some embodiments, the NFC module may indicate when it desires to change operational modes to enable an image data source to adjust image content and, thus, corresponding image data accordingly. 
     With the foregoing in mind, an electronic device  10 , which may utilize an electronic display  12  to display images and an NFC module  25 , is shown in  FIG. 1 . As will be described in more detail below, the electronic device  10  may be any suitable computing device, such as a handheld computing device, a tablet computing device, a notebook computer, and/or the like. Thus, it should be noted that  FIG. 1  is merely one example of a particular implementation and is intended to illustrate the types of components that may be present in the electronic device  10 . 
     In the depicted embodiment, the electronic device  10  includes the electronic display  12 , one or more input devices  14 , one or more input/output (I/O) ports  16 , a processor core complex  18  having one or more processor(s) or processor cores, memory  20  that may be local to the device  10 , a main memory storage device  22 , a network interface  24 , an NFC module  25 , a power source  26 , and image processing circuitry  27 . The various components described in  FIG. 1  may include hardware elements (e.g., circuitry), software elements (e.g., a tangible, non-transitory computer-readable medium storing instructions), or a combination of both hardware and software elements. It should be noted that the various depicted components may be combined into fewer components or separated into additional components. For example, the memory  20  and the main memory storage device  22  may be included in a single component. Additionally, the image processing circuitry  27  (e.g., a graphics processing unit (GPU)) may be included in the processor core complex  18 . 
     As depicted, the processor core complex  18  is operably coupled with memory  20  and the main memory storage device  22 . In some embodiments, the memory  20  and/or the main memory storage device  22  may be tangible, non-transitory, computer-readable media that stores instructions executable by the processor core complex  18  and/or data to be processed by the processor core complex  18 . For example, the memory  20  may include random access memory (RAM) and the main memory storage device  22  may include read only memory (ROM), rewritable non-volatile memory such as flash memory, hard drives, optical discs, and/or the like. 
     In some embodiments, the processor core complex  18  may execute instructions stored in memory  20  and/or the main memory storage device  22  to perform operations, such as signaling the NFC module  25  to emit electromagnetic waves. As such, the processor core complex  18  may include one or more general purpose microprocessors, one or more application specific processors (ASICs), one or more field programmable logic arrays (FPGAs), or any combination thereof. 
     Further, as depicted, the processor core complex  18  is operably coupled with I/O ports  16 , which may enable the electronic device  10  to interface with various other electronic devices. For example, a portable storage device may be connected to an I/O port  16 , thereby enabling the processor core complex  18  to communicate data with a portable storage device. In this manner, the I/O ports  16  may enable the electronic device  10  to output image content to the portable storage device and/or receive image content from the portable storage device. 
     Furthermore, the processor core complex  18  is also operably coupled to the power source  26 , which may provide power to the various components in the electronic device  10 . The power source  26  may include any suitable source of energy, such as a rechargeable lithium polymer (Li-poly) battery and/or an alternating current (AC) power converter. As depicted, the processor core complex  18  is operably coupled with input devices  14 , which may enable a user to interact with the electronic device  10 . In some embodiments, the inputs devices  14  may include buttons, keyboards, mice, trackpads, and the like. 
     Additionally, as depicted, the processor core complex  18  is operably coupled with the network interface  24 . Using the network interface  24 , the electronic device  10  may communicatively couple to a communication network and/or other electronic devices. For example, the network interface  24  may connect the electronic device  10  to a personal area network (PAN), such as a Bluetooth network, a local area network (LAN), such as an 802.11x Wi-Fi network, and/or a wide area network (WAN), such as a 4G or LTE cellular network. In this manner, the network interface  24  may enable the electronic device  10  to transmit image content to a network and/or receive image content from the network for display on the electronic display  12 . 
     The network interface  24  may be coupled with the NFC module (e.g., device)  25  that may enable the electronic device  10  to wirelessly communicate with another electric device, such as a standalone NFC device and/or another NFC module implemented in the other electronic device. Further, the NFC module  25  may transmit and receive data (e.g., information) to/from the network interface  24  that may be communicated to another electronic device capable of near-field communication. Generally, the NFC module  25  may use electromagnetic (e.g., radio frequency) waves to wirelessly communicate the data. Additionally, the NFC module  25  may be implemented in a device acting as an active NFC reader (e.g., NFC module operating in an active NFC reader mode) that reads data from a device acting as a passive NFC tag (e.g., NFC module operating in a passive NFC tag mode). Alternatively, the NFC module  25  may be implemented in a device acting as a passive NFC tag that transmits information to a device acting as an active NFC reader. To facilitate operation mode of the NFC module  25 , the NFC module  25  may be operably coupled to the processor core complex  18 . The processor core complex  18  may act as an NFC controller that may control parameters (e.g., timing and/or duration) of the NFC module  25  emission period to reduce overlap between emission period and display  12  refresh period, thereby reducing the perceptibility of display artifacts (e.g., muras). 
     The electronic display  12  may use, for example, organic light-emitting diode (OLED) or liquid-crystal display (LCD) technology to present visual representations of information by display images such, as a graphical user interface (GUI) of an operating system, an application interface, a still image, or video content. As described above, the electronic display  12  may display the images based on image content received from memory  20 , a storage device (e.g., main memory storage device  22  and/or an external storage device), and/or another electronic device  10 , for example, via the network interface  24  and/or the I/O ports  16 . The electronic display  12  may display the images once the image content has been fetched from memory  20  and processed by the image processing circuitry  27 . The electronic display  12  may also include touch components that enable user inputs to the electronic device  10  by detecting occurrence and/or position of an object touching its screen (e.g., surface of the electronic display  12 ). 
     As described above, the electronic device  10  may be any suitable electronic device. To help illustrate, one example of a suitable electronic device  10 , specifically a handheld device  10 A, is shown in  FIG. 2 . In some embodiments, the handheld device  10 A may be a portable phone, a media player, a personal data organizer, a handheld game platform, and/or the like. For illustrative purposes, the handheld device  10 A may be a smart phone, such as any iPhone® model available from Apple Inc. 
     As depicted, the handheld device  10 A includes an enclosure  28  (e.g., housing). In some embodiments, the enclosure  28  may protect interior components from physical damage and/or shield them from electromagnetic interference. Additionally, as depicted, the enclosure  28  surrounds the electronic display  12 . In the depicted embodiment, the electronic display  12  is displaying a graphical user interface (GUI)  30  having an array of icons  32 . By way of example, when an icon is selected either by an input device  14  or a touch-sensing component of the electronic display  12 , an application program may launch. 
     Furthermore, as depicted, input devices  14  open through the enclosure  28 . As described above, the input devices  14  may enable a user to interact with the handheld device  10 A. For example, the input devices  14  may enable the user to activate or deactivate the handheld device  10 A, navigate a user interface to a home screen, navigate a user interface to a user-configurable application screen, activate a voice-recognition feature, provide volume control, and/or toggle between vibrate and ring modes. As depicted, the I/O ports  16  also open through the enclosure  28 . In some embodiments, the I/O ports  16  may include, for example, an audio jack to connect to external devices. 
     To further illustrate, another example of a suitable electronic device  10 , specifically a tablet device  10 B, is shown in  FIG. 3 . For illustrative purposes, the tablet device  10 B may be any iPad® model available from Apple Inc. A further example of a suitable electronic device  10 , specifically a computer  10 C, is shown in  FIG. 4 . For illustrative purposes, the computer  10 C may be any Macbook® or iMac® model available from Apple Inc. Another example of a suitable electronic device  10 , specifically a watch  10 D, is shown in  FIG. 5 . For illustrative purposes, the watch  10 D may be any Apple Watch® model available from Apple Inc. As depicted, the tablet device  10 B, the computer  10 C, and the watch  10 D each also includes an electronic display  12 , input devices  14 , I/O ports  16 , and an enclosure  28 . 
     As described above, the electronic device  10  may include an electronic display  12  that may display images based at least in part on the image content, for example, retrieved from the local memory  20  and/or the main memory storage device  22 . Additionally, as described above, an electronic device  10  may include an NFC module  25  to facilitate wireless data communication with another electronic device  10 , such as a standalone NFC device and/or another NFC module  25  implemented in the other electronic device  10 . In some embodiments, operational timing of the electronic display  12  and the NFC module  25  may be coordinated (e.g., controlled), for example, to reduce (e.g., minimize) overlap between emission periods of the NFC module  25  and refresh periods of the electronic display  12 . 
     To help illustrate, a portion  100  of the electronic device  10 , which includes an electronic display  12  and an NFC module  25 , is shown in  FIG. 6 . In some embodiments, a controller  108  may control operations of the NFC module  25 , the electronic display  12 , and/or an image source  106 . For example, the controller  108  may synchronize emission of NFC (e.g., electromagnetic and/or radio frequency) waves from the NFC module  25  with the blanking period of the electronic display  12 . Although depicted as a single controller  108 , in some embodiments, an individual controller may be implemented for each of the NFC module  25 , the electronic display  12 , and/or the image source to control operation. As another example, synchronization signal may be generated by the electronic display  12  and directly sent to the NFC module  25  and vice versa. Further, controllers may be added to smooth the timing sequence during the transition of the NFC modes, as will be discussed in more detail below. Furthermore, additional controllers may be added for better user front-of-screen and NFC communication experience. 
     To facilitate controlling operations, the controller  108  may include a controller processor  110  and controller memory  112 . In some embodiments, the controller processor  110  may execute instructions stored in the controller memory  112 . Thus, in some embodiments, the controller processor  110  may be included in the processor core complex  18 , the image processing circuitry  27 , a timing controller in the electronic display  12 , a separate processing module, or any combination thereof. Additionally or alternatively, the controller memory  112  may be included in local memory  20 , the main memory storage device  22 , internal memory of the NFC module  25 , a separate tangible, non-transitory, computer readable medium, or any combination thereof. 
     In some embodiments, the controller  108  may be operably coupled to an image source  106 . The image source  106  may be a memory buffer, a portion of the memory storage device  22 , and/or the like. The image source  106  may hold image data (e.g., content) to be presented via the electronic display  12 . In some embodiments, the controller  108  may additionally or alternatively be coupled to the electronic display  12 . The controller  108  may be a timing controller (TCON) that may active and deactivate the display pixels  114  when displaying different image frames. Further, the controller  108  may synchronize when new image content is sent from the image source  106  to the electronic display  12  and display pixels  114 . The controller  108  may also control the refresh rate of the electronic display  12  and thereby the refresh period and blanking period durations. 
     The controller  108  may interface with the display driver  116  to populate (e.g., write or refresh) the display pixels  114  with the image content at the appropriate time. The display pixels  114  may be LCD or OLED technology which may have similar operational principles. For example, the electronic display  12  may generally display image frames by controlling luminance of the display pixels  114  based in part on image content stored within the display pixels  114 . Although a single display pixel  114  is shown, it should be appreciated that a display may include several hundreds to several million display pixels  114 , each with its own storage component  118 . 
     The storage component  118  may be, for example, a storage capacitor that stores an amount of charge corresponding to the image data of that display pixel  114 . Depending on the display technology, the capacitor voltage may be used to generate a luminance proportional to the image content (e.g., bit value of image content). For example, OLEDs may use the capacitor voltage to operate a driving trans-film transistor (TFT) in the active region, thereby controlling the magnitude of the supply current to the organic layer of the OLED pixel. The image content may be sent to and stored in the storage component  118  during the refresh period of the electronic display  12 . 
     In some embodiments, the controller  108  may be additionally or alternatively coupled with the NFC module  25 . In such instances, the controller  108  may act as an NFC controller used to time the emission of NFC electromagnetic waves, adjust the duration of the NFC emission period, determine the operational mode (e.g., polling mode, reading mode, and/or object-detection mode) of the NFC module  25 , and/or the like. The NFC module  25  may include a transceiver  120  capable of both transmitting and receiving NFC electromagnetic waves  122  depending on whether the electronic device  10  is acting as a passive or active NFC device. It should be appreciated that although an NFC module  25  is shown and described, any radio frequency transmitter may be implemented by the electronic device  10  to facilitate communication with other devices. 
     The NFC module  25  may include an antenna  124  to facilitate emission of NFC waves  122  from the NFC module  25 . However, because NFC technology relies on magnetic induction to drive the transfer of information from one device to another, in some embodiments, the antenna  124  may vary from a traditional radio frequency antenna, for example, such that the antenna  124  may be better thought of as a large inductor. 
     Inductors are coils that may generate a low frequency radio-wave field (i.e., magnetic field) when current flows through the coils. Inductors may be coupled together (e.g., mutual coupling) when the magnetic field of one inductor permeates the coils of a second inductor (e.g., antenna  126 ) because the magnetic field induces a current within the second inductor (e.g., NFC electromagnetic waves  122  transmitted to the passive NFC device  128 ). This may be known as charging or activating the passive NFC device and allows for contactless energy transfer between devices that NFC technology is built upon. 
     For example, the controller  108  may signal (e.g., instruct) the NFC module  25  to act as an active NFC device (e.g., NFC reader) and emit NFC electromagnetic waves  122  to a passive NFC device  128  (e.g., NFC tag) upon detecting the presence of a passive NFC device  128 . The transceiver  120  may use the inductor antenna  124  to transmit the NFC electromagnetic waves  122  by running current through the inductor antenna  124  at radio frequencies (e.g., 13.56 MHz). The coils of the inductor antenna  124  generate a magnetic field that is emitted for short distances (e.g., 4 cm). 
     When the passive NFC device  128  is brought within a threshold (e.g., short) distance of the inductor antenna  124  of the active NFC device, mutual coupling between the inductor antennas  124  and  126  may occur, thereby charging the NFC tag. That is, the NFC electromagnetic waves generated when the inductor antenna  124  generates the magnetic field induce an electric current in the inductor antenna  126  of the passive NFC device  128 . The induced electric current may induce a magnetic field that interacts with the NFC electromagnetic waves  122  generated by the inductor antenna  124 . The transceiver  120  may detect the induced magnetic field, for example, based on an analog electrical signal generated by the inductor antenna  124  to read the information (e.g., data) provided by the passive NFC device  128 . 
     In this instance, the electronic device  10  including the NFC module  25  is referred to as the active NFC device since the electronic device  10  is using power to generate NFC electromagnetic waves  122  via the magnetic field (e.g., running current through the inductor antenna  124 ). The passive NFC device  128  is considered passive as either it does not have its own power supply and/or has turned off its power supply, relying on mutual coupling for the energy source. Thus, the active NFC device may send the NFC electromagnetic waves  122  and the passive NFC device  128  may accept the NFC electromagnetic waves  122 . It should be understood that while the NFC module  25  has been shown as part of an active NFC device, the device may also act passively, allowing for another active NFC device to generate the magnetic field to read information from the portion  100  of the device  10 . 
     Since NFC technology relies on NFC electromagnetic waves  122  generated during magnetic induction to transfer information, the magnetic field that appears when NFC electromagnetic waves  122  are emitted may affect the storage of image content in the display pixels  114  when the magnetic field interacts with the electronic display  12 . For example, the storage component  118  may be a storage capacitor that stores charge during the refresh period corresponding to the luminance of the image content. Because the NFC module  25  may be in close proximity to the display pixels  114  in more compact electronic device  10  designs, the magnetic field generated by the NFC module  25  during emission of NFC electromagnetic waves  122  may permeate through the display pixels  114 . The magnetic field may increase or decrease the amount of charge stored in the storage capacitor in the storage component  118 . 
     The charge stored affects the voltage available for driving the display pixel  114 . For example, if the magnetic field causes less charge to be stored in the storage component  118  than the correct amount of charge corresponding to the image content, less voltage is available to drive the trans-film transistor (TFT) resulting in less luminance from that pixel. The magnetic field may cause such patterned voltage imbalances that may appear as visible artifacts, such as muras. However, by synchronizing the blanking period of the electronic display  12  and the emission period of the NFC electromagnetic waves  122 , likelihood that the magnetic field generated by the NFC technology affect electrical energy stored in display pixels of the electronic display  12  may be reduced, thereby mitigating the appearance of display artifacts caused by the emission of NFC electromagnetic waves  122 . 
     To help further illustrate,  FIG. 7  describes a process  150  for timing the emission of NFC electromagnetic waves  122  and the display blanking period such that the emission period overlaps with the blanking period instead of the refresh period. Generally process  150  includes determining a desire to output NFC electromagnetic wave (process block  152 ), determining the electronic display  12  refresh period (process block  154 ), and outputting the NFC electromagnetic wave  122  during the blanking period of the electronic display  12  (process block  156 ). While process  150  is described using steps in a specific sequence, it should be understood that the present disclosure contemplates that the described steps may be performed in different sequences than the sequence illustrated, and certain described steps may be skipped or not performed altogether. In some embodiments, at least some of the steps of the process  150  may be implemented at least in part by a processor core complex  18  and/or the controller  108  that executes instructions stored in a tangible, non-transitory, computer-readable medium, such as the memory  20 . In alternative or additional embodiments, at least some steps of the process  150  may be implemented by any other suitable components or control logic, such as another electronic device, and/or the like. Furthermore, it should be appreciated that the process  150  may apply to any radio frequency waves that are transmitted from, for example, a radio frequency transceiver and may cause the appearance of display artifacts. 
     Thus, in some embodiments, the controller  108  may determine the desire to output a NFC electromagnetic wave  122  (process block  152 ). For example, upon detection by the controller  108  and/or NFC module  25  that a passive NFC device  128  is within proximity, the controller  108  may signal the NFC module  25  to read the passive NFC device  128  by emitting NFC electromagnetic waves  122  of 30 μs durations. Further, the controller  108  may determine the electronic display  12  refresh period (process block  154 ). That is, the controller  108  may determine, based on a current or new refresh rate, when the refresh period is occurring (e.g., image content is being sent to the display pixels  114 ) and when the blanking period is occurring. 
     Based on the desire to output NFC electromagnetic waves  122  of a specific duration and on the duration of the display refresh period, the controller  108  may synchronize the output of the NFC electromagnetic waves  122  during the blanking period of the electronic display  12  to reduce the effect of the NFC electromagnetic waves  122  on the storage component  118  (process block  156 ). For example, the controller  108  may determine that the emission duration of the NFC electromagnetic waves  122  is greater than the blanking period of the electronic display  12  and may break up the emission of the NFC electromagnetic waves  122  to fit within the blanking period. Additionally or alternatively, the controller  108  may determine that the blanking period of the electronic display  12  may be extended to accommodate for a longer emission period duration for NFC electromagnetic waves  122  and, thus, may adjust the refresh rate of the electronic display  12 . 
     To further illustrate the synchronization of the emission period of NFC electromagnetic waves  122  with the electronic display  12  blanking period,  FIG. 8  is a timing diagram describing NFC activity and display activity while the NFC module is operating in an object-detection mode. As depicted, the display may have a frame time (e.g., image display duration) dictated by the current refresh rate. The frame time may be divided into a refresh period  202  and a blanking period  204 . During the refresh period  202 , the electronic display  12  may write an image to its display pixels  114  by controlling storage of electrical energy in each of the display pixels, for example, by successively connecting the storage components  118  of the display pixels  114  to corresponding data lines. While ceasing to refresh, the electronic display  12  continuing to displaying the image during the blanking period  204 , for example, by maintaining the storage components  118  of the display pixels  114  electrically disconnected from the data lines. 
     In some embodiments, a synchronization signal  206  (e.g., tearing effect (TE) signal and/or a vertical synchronization (V-synch) signal) may reflect the blanking period  204  and refresh period  202  of the electronic display  12 . For example, the synchronization signal  206  may be high (e.g., “1” bit or a first state) during the refresh period  202  when image content may be stored within the display pixels  114 . On the other hand, the synchronization signal  206  may be low (e.g., “0” bit or second state) during the blanking period  204  when no image content is being written to the display pixels  114 . In other words, the synchronization signal  206  may be triggered at the beginning of the refresh period to indicate that a new image frame may be drawn. 
     To facilitate operational synchronization, in some embodiments, the synchronization signal  206  may also be provided to other portions of the electronic device  10 . For example, in addition to the electronic display  12 , the electronic device  10  may provide the synchronization signal  206  to the controller  108  and/or directly to the NFC module  25  from the electronic display  12 . In this manner, operational timing of the NFC module  25  may also be controlled based on the synchronization signal  206 , for example, such that NFC module  25  does not output NFC electromagnetic waves while the synchronization signal  206  is high and/or only outputs NFC electromagnetic waves while the synchronization signal  206  is low. 
     In some instances, the NFC module  25  may spend a substantial amount of time in an object-detection mode. In some embodiments, the object-detection mode may provide low power functionality that saves energy and/or extends battery life of the electronic device  10 . Specifically, the object-detection mode may turn off the magnetic field (e.g., not emit NFC electromagnetic waves  122 ) when the NFC device is not near another NFC device. However, to detect a passive NFC device, the controller  108  may periodically signal the NFC module  25  to emit short impulse NFC electromagnetic waves  208 . As depicted, the short impulse NFC electromagnetic waves  208  may occur, for example, between refresh periods  202 , during the blanking period  204 , and when the synchronization signal  206  is low. 
     By emitting short impulse NFC electromagnetic waves  208  during the blanking period  204 , the magnetic field generated during emission of the short impulse NFC electromagnetic waves  208  may less likely affect the image content stored within the display pixels  114 , thereby reducing and/or eliminating the appearance of display artifacts. Further, when the short impulse NFC electromagnetic waves  208  interact with a potential passive NFC device  128 , an indication may be sent to the controller  108  to switch the NFC module  25  mode, adjust the emission duration of NFC electromagnetic waves  122 , and/or adjust the blanking period  204  duration of the electronic display  12 . In some instances, upon detecting a potential passive NFC device  128  the electronic display  12  may be immediately refreshed with image content held within the pixels and/or the refresh rate may be lowered to less than the polling mode rate. 
       FIG. 9  is a timing diagram  300  describing the NFC and display activity while the NFC module  25  is operating in a polling mode. As depicted, during polling mode, the NFC module  25  may emit longer duration NFC electromagnetic waves  122  to determine whether the potential passive NFC device is actually a NFC device or whether it is, for example, just a piece of metal. For example, the longer emission period  302  durations may allow for more NFC electromagnetic waves  122  to charge the potential passive NFC device. That is, longer emission period  302  durations may allow the magnetic field generated by the NFC module  25  to adequately interact with the potential passive NFC device to induce a radio-wave field. When the induced radio-wave field does not behave as expected if the potential passive NFC device  128  were actually a passive NFC device  128 , the controller  108  may signal to the NFC module  25  of the false positive and change the NFC module  25  mode back to the object-detection mode. 
     Because the emission period  302  duration may be longer when in the polling mode, the refresh rate of the electronic display  12  may be adjusted (e.g., to 1 Hz, less than the polling refresh rate). As depicted, the refresh rate of the display may decrease, resulting in less frequent refresh periods  304  and longer blanking periods  306 . The longer blanking periods  306  may allow for enough time for the NFC electromagnetic waves  122  to be emitted without causing display artifacts since image content may not be stored in the display pixels  114  during the blanking period  306 . The synchronization signal  308  may be used to by the controller  108  to synchronize the display activity with the NFC module  25  activity, for example, to avoid overlap between the emission period and the refresh period  304 . In some embodiments, the synchronization signal  308  may be transmitted to the transceiver  120  from the controller  108  and/or directly from the electronic display  12  to facilitate synchronizing the operation of the NFC module  25  with the electronic display  12 . 
     The refresh rate of the electronic display  12  may be adjusted by storing image content that does not require fast refresh rates in the display pixels  114 . For example, still images may be stored in the display pixels  114  for display instead of fast moving images since fast moving images require fast refresh rates to avoid image blurring. The change in image content may occur towards the end of the object-detection mode once a potential passive NFC device has been detected or at the beginning of the polling mode. 
     Further, the emission period  302  duration may be also or alternatively reduced, for example, to avoid dramatic reduction of the refresh rate when a higher refresh rate may be desirable. In particular, the emission period  302  may be longer during polling mode to ensure that the potential passive NFC device is adequately charged via mutual coupling. By increasing the strength of the magnetic field carried by the NFC electromagnetic waves  122 , the energy transferred to the potential passive NFC device occurs at a faster rate. Thus, a shorter emission period  302  that may fit within the blanking period  306  of a faster refresh rate may be used to adequately charge the potential passive NFC device. Additionally, both the refresh rate and emission period  302  duration may be adjusted by the controller  108  to reduce overlap in emission period  302  and refresh period  304  while reducing and/or mitigating the appearance of display artifacts. 
     Upon determining that the potential passive NFC device is indeed an NFC device (e.g., tag engagement), the NFC module  104  may enter read mode. To help illustrate, a timing diagram  350  that describes the NFC and display activity while the NFC module  25  operates in a reading mode is shown in  FIG. 10 . In the reading mode, the NFC module  25  may transmit NFC electromagnetic waves  122  to the passive NFC device  128  and read information held by the passive NFC device  128 . 
     During reading mode, the emission period  352  of the NFC electromagnetic waves  122  may be longer than the emission periods during the object-detection mode  208  and/or during the polling mode  302  since information is being transferred from the passive NFC device  128  to the active NFC device. To prevent the longer duration NFC electromagnetic waves  122  from causing display artifacts, the refresh rate of the display may be further adjusted (e.g., minimum refresh rate). As depicted, the refresh period  354  may occur less frequently and the blanking period  356  may be relatively long. Further, as depicted, NFC electromagnetic waves  122  may be emitted for most of the blanking period  356 . 
     In particular, the longer emission period  352  and the refresh period  354  may by synchronized by a controller  108  such that the periods do not overlap. In some instances, the controller  108  may use the synchronization signal  358  to determine when the blanking period  356  is occurring and when to signal the NFC module  25  to emit NFC electromagnetic waves  122 . Alternatively, in some embodiments, the controller  108  may pause monitoring of the synchronization ssignal  358  upon entering reading mode as the blanking period  356  may last the entire duration of the reading mode. Additionally, the controller  108  may adjust the refresh rate and the emission period  352  duration. 
     For example, the controller  108  may store black images in the display pixels  114 . Perceived image quality of black images (e.g., absence of voltage on the storage capacitor) may be maintained with minimal refreshing. Thus, the blanking period  356  may be long enough that the emission period  352  safely overlaps only the blanking period  356  and not the refresh period  354 , thereby mitigating the appearance of display artifacts, such as muras. Using black images or low voltage images during the read period is also advantageous because less charge is stored in the display pixels  114  for displaying such images. As such, the magnetic field generated during NFC electromagnetic wave  122  emissions may have less perceivable effect on the displayed image content. That is, the black image may hide any display artifacts induced by the magnetic field. The electronic display  12  may be refreshed with a black image upon determination of the passive NFC device  128  or at the initiation of the reading mode. After the information has been transferred from the passive NFC device  128  to the active NFC device (e.g., read finished  360 ), the NFC module  25  may return to polling mode or to object-detection mode. 
     Further, in some embodiments, the shape of the NFC antenna  124 / 126  inductor coil and/or the location of the inductor coil relative to the display  12  may affect where the display artifacts are induced on the electronic display  12 . For example, the coil shape may cause most of the display artifacts, such as muras, to appear on the edges of the display  12 . In such instances, an image with a mostly black background (e.g., an image with a black border of a large width) may be stored in the display pixels  114  instead of the purely black image since such an image may be sufficient to hide any display artifacts induced by the magnetic field. 
     A process  400  for adjusting the display refresh period based on NFC electromagnetic wave properties to reduce overlap of the NFC emission period and the display refresh period is described in  FIG. 11 . Generally, the process  400  includes determining the parameters of the target NFC electromagnetic wave  122  (process block  402 ), determining the initial refresh period of the electronic display  12  (process block  404 ), and adjusting the refresh period of the electronic display  12  based on the target NFC electromagnetic wave parameters (process block  406 ). While process  400  is described using steps in a specific sequence, it should be understood that the present disclosure contemplates that the described steps may be performed in different sequences than the sequence illustrated, and certain described steps may be skipped or not performed altogether. In some embodiments, at least some of the steps of the process  400  may be implemented at least in part by a processor core complex  18  and/or the controller  108  that executes instructions stored in a tangible, non-transitory, computer-readable medium, such as the memory  20 . In alternative or additional embodiments, at least some steps of the process  400  may be implemented by any other suitable components or control logic, such as another electronic device, and the like. Furthermore, it should be appreciated that the process  400  may apply to any radio frequency waves that are transmitted from, for example, a radio frequency transceiver and may cause the appearance of display artifacts. 
     Thus, in some embodiments, the controller  108  may determine target parameters of the NFC electromagnetic waves  122  (process block  402 ). In some embodiments, the parameters may include the amount of energy that must be transferred, the pulse duration of the target NFC electromagnetic waves  122 , and the frequency of the pulse durations. For example, more energy must be transferred to the passive NFC device  128  by the target NFC electromagnetic waves  122  during polling mode (e.g., charging the tag) than during object-detection mode (e.g., discovering a potential tag). As another example, the pulse duration may be shorter when discovering a potential tag than when reading information from a tag. 
     Additionally, the controller  108  may determine the initial refresh period of the electronic display  12  (process block  404 ). The refresh rate of the display may determine the frequency of the refresh period. Further, display technology, for example, may determine the duration of the refresh period since some display technology requires less time to store (e.g., refresh) image content into display pixels  114 . 
     Furthermore, the controller  108  may adjust the refresh period of the electronic display  12  based on the target NFC electromagnetic wave parameters, for example, when the target NFC electromagnetic wave parameters cannot be adjusted without compromising communication quality (process block  406 ). Additionally or alternatively, the refresh rate may be adjusted, for example, when system components (e.g., battery) requires fixed NFC electromagnetic wave parameters (e.g., fixed pulse strength to preserve battery life). Moreover, in some embodiments, image content to be displayed may be adjusted based at least in part on refresh rate. For example, the controller  108  may instruct the image source  106  to change image content from a fast image (e.g., an image that travels a large number of pixels between image frames) to a slow or still image. As another example, the controller  108  may instruct the image source  106  to change image content to a black image so that little to no refreshing is required. 
     To help further illustrate, a process  450  for adjusting the NFC electromagnetic wave properties based on the display refresh rate to reduce overlap of the NFC emission period and the display refresh period is described in  FIG. 12 . Generally, the process  450  includes determining the target refresh period of the electronic display  12  (process block  452 ), determining the initial NFC electromagnetic wave parameters (process block  454 ), and adjusting the NFC electromagnetic wave parameters based on the target refresh period (process block  456 ). While process  450  is described using steps in a specific sequence, it should be understood that the present disclosure contemplates that the described steps may be performed in different sequences than the sequence illustrated, and certain described steps may be skipped or not performed altogether. In some embodiments, at least some of the steps of the process  450  may be implemented at least in part by a processor core complex  18  and/or the controller  108  that executes instructions stored in a tangible, non-transitory, computer-readable medium, such as the memory  20 . In alternative or additional embodiments, at least some steps of the process  450  may be implemented by any other suitable components or control logic, such as another electronic device, and the like. Furthermore, it should be appreciated that the process  450  may apply to any radio frequency waves that are transmitted from, for example, a radio frequency transceiver and may cause the appearance of display artifacts. 
     Thus, in some embodiments, the controller  108  may determine the target refresh period of the electronic display  12  (process block  452 ). The refresh rate of the display may determine the frequency of the refresh period. Further, display technology, for example, may determine the duration of the refresh period since some display technology requires less time to store (e.g., refresh) image content into display pixels  114 . 
     Additionally, the controller  108  may determine the initial NFC electromagnetic wave parameters (process block  454 ). In some embodiments, the parameters may include the amount of energy that must be transferred, the pulse duration of the initial NFC electromagnetic waves  122 , and the frequency of the pulse durations. For example, more energy must be transferred to the passive NFC device  128  by the NFC electromagnetic waves  122  during polling mode than during object-detection mode. 
     Based on the target refresh period of the electronic display  12 , the controller  108  may instruct the NFC module  25  to adjust its NFC electromagnetic wave parameters, for example, when the refresh period may not be adjusted without compromising perceived image quality (process block  456 ). For example, the refresh period may not be changed when the display pixels require a minimum amount of time to store image contents. Further, the refresh period may not be adjusted when the image content is a fast moving image and cannot be substituted by a slow moving or still image. In such instances, the NFC electromagnetic wave parameters may be adjusted by changing the strength of the NFC electromagnetic waves  122 . For example, if the passive NFC device  128  requires X amount of energy to produce an induced radio-wave field, the active NFC device may increase the strength of the NFC electromagnetic waves  122  to transfer X amount of energy in a shorter amount of time, thereby reducing the NFC emission period and, thus, potential overlap with display refresh periods. 
     Additionally or alternatively, the controller  108  may adjust the allowed time for the emission of the NFC electromagnetic waves based on the target refresh period of the electronic display  12  in an asynchronized format (process block  456 ). For example, a synchronization signal generated by the display  12  may indicate to the NFC module  104  to stop emission of NFC electromagnetic waves during refresh periods of the display  12 . In some embodiments, the NFC module  104  may have an interrupt mechanism that is triggered when the synchronization signal indicates that the display  12  is or has entered the refresh period. In such cases, the parameters of the NFC electromagnetic waves (e.g., strength, duration) may be modified or may remain unmodified. 
     It should also be noted that in some embodiments, both the refresh period of the display and the NFC electromagnetic wave parameters may be adjusted to reduce overlap. For example, a black image may be written to the display pixels  114  and the refresh rate may be significantly reduced. As the same time, the NFC pulse duration may be shortened by increasing the strength of the NFC electromagnetic waves  122 , for example, when extending the battery life is not a concern. Such a combination reduces the appearances of display artifacts that are more likely to occur when the strength of the NFC electromagnetic waves  122  is relatively high. 
     Display artifacts, such as muras, arising from interactions between NFC electromagnetic waves  122  and an electronic display  12  may be reduced and/or eliminated by controlling the emission of NFC electromagnetic waves  122  relative to the refresh period of the electronic display  12 . An NFC module  25  within an electronic device  10  may be used by the electronic device  10  for contactless communication at short distances with another NFC device and/or NFC tag. In some instances, the overlap of the emission period of the NFC electromagnetic waves  122  with the refresh period of the electronic display  12  may result in display artifacts. Thus, to reduce the appearance of artifacts on the electronic display  12  of electronic devices  10  using NFC technology, timing of the emission period of NFC electromagnetic waves  122  and/or the refresh rate may be adjusted to stagger the emission period and refresh period. 
     The specific embodiments described above have been shown by way of example, and it should be understood that these embodiments may be susceptible to various modifications and alternative forms. It should be further understood that the claims are not intended to be limited to the particular forms disclosed, but rather to cover all modifications, equivalents, and alternatives falling within the spirit and scope of this disclosure.

Metadata:
Filing Date: 20180727
Publication Date: 20200428
Grant Date: 20200428
Priority Date: 20180409
Inventors: KOO, KYUNG HOAE
YAO, WEIJUN
CHU, YUE JACK
SUN, KAIGE
Assignee: APPLE INC
CPC Classifications: [{"code": "G09G2310/06", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/20", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2380/06", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G5/12", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2340/0435", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0209", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/3208", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2330/06", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2370/16", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0257", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2330/06", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/36", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2340/0435", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/3266", "inventive": true, "first": true, "tree": "[]"}, {"code": "G09G2330/06", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0209", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04B5/0025", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2340/0435", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/3266", "inventive": true, "first": true, "tree": "[]"}, {"code": "G09G2320/0257", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/14", "inventive": true, "first": true, "tree": "[]"}, {"code": "G09G3/20", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04B5/70", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04B5/70", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 68097303