PATENT DOCUMENT

Publication Number: US-11221355-B2
Application Number: US-201815944495-A
Country: US
Kind Code: B2

Title: Effective series resistance display sensing

Abstract:
Methods and systems for compensating display panel operations providing a current from power circuitry over a first path between a display panel and the power circuitry are provided. A sensing current may be injected into the first path via a second path between the power circuitry and the first path. An equivalent series resistance (ESR) of the first path may be calculated using a third path and the sensing current. A processor may compensate for electrical fluctuations from the power circuitry to the display panel based at least in part on the measured ESR.

Claims:
What is claimed is: 
     
       1. A method comprising:
 providing a current from power circuitry over a first path between a display panel and the power circuitry; 
 generating a sensing current using a current chopper to modulate the sensing current; 
 injecting the sensing current into the first path via a second path between the power circuitry and the first path; 
 measuring an equivalent series resistance (ESR) of the first path using a third path and the sensing current; and 
 compensating for electrical fluctuations from the power circuitry to the display panel based at least in part on the measured ESR, wherein the first, second, and third paths comprise distinct hardwired paths that are each separately and concurrently coupled from the power circuitry to the display panel. 
 
     
     
       2. The method of  claim 1 , wherein generating the sensing current comprises receiving a chopping frequency used to modulate the sensing current. 
     
     
       3. The method of  claim 2 , wherein the chopping frequency is configured to reduce or minimize visibility of the sensing current on the display panel. 
     
     
       4. The method of  claim 3 , wherein the chopping frequency comprises a frequency that is above a threshold of human detectability. 
     
     
       5. The method of  claim 3 , wherein the chopping frequency is selected to prevent synchronization with operation of the power circuitry. 
     
     
       6. The method of  claim 1 , wherein measuring the ESR comprises:
 combining the sensing current and the current into a combined signal in the third path; and 
 receiving the combined signal at the power circuitry via the third path. 
 
     
     
       7. The method of  claim 6  comprising demodulating the combined signal after receipt via the third path. 
     
     
       8. The method of  claim 7 , comprising filtering the demodulated combined signal to generate an ESR measurement. 
     
     
       9. The method of  claim 1 , wherein the current is an operating current used to operate the display panel. 
     
     
       10. The method of  claim 1 , comprising tracking current drop between the display panel and the power circuitry by measuring the ESR. 
     
     
       11. A system comprising:
 a plurality of routes between power circuitry and a display panel; and 
 the power circuitry, wherein the power circuitry is configured to provide power management for the display panel and to determine electrical properties of at least one of the plurality of routes, wherein the power circuitry couples to the plurality of routes and comprises:
 a first node to receive a first route of the plurality of routes; 
 a second node to receive a second route of the plurality of routes; 
 a third node to receive a third route of the plurality of routes; 
 a current chopper to inject via the second node a sensing current on top of a signal over the first route to form a combined signal; 
 a demodulator to extract the signal from the combined signal received at the third node; and 
 a filter to extract an electrical property of the first route from the demodulated combined signal, wherein the first, second, and third routes comprise distinct hardwired paths that are each separately and concurrently coupled from the display panel to the power circuitry. 
 
 
     
     
       12. The system of  claim 11 , wherein the third node comprises a high impedance node relative to the first node. 
     
     
       13. The system of  claim 11 , wherein the electrical property comprises an equivalent series resistance (ESR) of the first route. 
     
     
       14. The system of  claim 13  comprising a processor configured to compensate the power management for ESR changes in the first route due to a temperature of the first route or an operating condition of the display panel. 
     
     
       15. The system of  claim 11  comprising calculation circuitry that receives the electrical property and is used to calculate a current based on the electrical property and a voltage derived from the combined signal using a low pass filter. 
     
     
       16. The system of  claim 15  comprising a processor configured to compensate the power management of the power circuitry for changes to the current. 
     
     
       17. The system of  claim 11 , wherein the power circuitry is configured to monitor a voltage at the display panel through the first route. 
     
     
       18. The system of  claim 17  comprising a processor configured to compensate the power management for changes to the voltage. 
     
     
       19. A method comprising:
 supplying a current over a first path between a display panel and power circuitry; 
 generating a sensing current using a current chopper to modulate the sensing current; 
 injecting the sensing current onto the first path via a second path from the display panel to a node on the first path at the display panel; 
 measuring an equivalent series resistance for the first path using a third path from the power circuitry to the node; 
 calculating supplied electrical parameters supplied from the power circuitry via the first path to the node based at least in part on the equivalent series resistance; and 
 compensating operation of the power circuity for changes to the supplied electrical parameters, wherein the first, second, and third paths comprise distinct hardwired paths that are each separately and concurrently coupled from the power circuitry to the display panel during driving of the display panel by the power circuitry.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a Non-Provisional Patent Application of U.S. Provisional Patent Application No. 62/555,912, entitled “Effective Series Resistance Display Sensing”, filed Sep. 8, 2017, which is herein incorporated by reference in its entirety for all purposes. 
    
    
     BACKGROUND 
     The present disclosure relates generally to techniques to sensing parameters in a display. More specifically, the present disclosure relates generally to techniques for sensing operational parameter changes of the display during operation of the 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 display panels are used in a plethora of electronic devices. These display panels typically include multiple pixels that emit light. The 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 display). Power supplied to the display panels may pass through various components, such as contacts and traces, that have some resistance. This resistance may change due to temperature and/or operating conditions of the display panel. Accordingly, the power supplied to the display panel may vary, causing emission of the display panel to vary. 
     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. 
     Display panel performance may change with temperature and/or operating conditions of the display panel (e.g., current draw and/or locations of content). The display panel performance may change when an effective series resistance (ESR) changes between power circuitry and a display panel. This ESR change causes a current supplied to the display panel to drop. Using real-time measurements of the ESR may enable the display to appear more uniform across multiple different temperatures and/or operating conditions of the display. Furthermore, once the ESR is calculated, the current and/or voltage at an end of a route from the power circuitry to the display panel may be measured. When this current and/or voltage changes, the power circuitry may be driven differently to compensate for the change. For example, when the voltage across an organic light emitting diode (OLED) drops, a corresponding voltage (e.g., ELVDD or ELVSS) may be adjusted in a corresponding direction, such as increasing EVLDD and/or decreasing ELVSS, to achieve a target voltage across the OLED. 
    
    
     
       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 schematic block diagram of an electronic device including a display, in accordance with an embodiment; 
         FIG. 2  is a perspective view of a notebook computer representing an embodiment of the electronic device of  FIG. 1 , in accordance with an embodiment; 
         FIG. 3  is a front view of a hand-held device representing another embodiment of the electronic device of  FIG. 1 , in accordance with an embodiment; 
         FIG. 4  is a front view of another hand-held device representing another embodiment of the electronic device of  FIG. 1 , in accordance with an embodiment; 
         FIG. 5  is a front view of a desktop computer representing another embodiment of the electronic device of  FIG. 1 , in accordance with an embodiment; 
         FIG. 6  is a front view of a wearable electronic device representing another embodiment of the electronic device of  FIG. 1 , in accordance with an embodiment; 
         FIG. 7  illustrates a block diagram view of a display system, in accordance with an embodiment; 
         FIG. 8  illustrates a schematic diagram of circuitry having a self-emissive unit, in accordance with an embodiment; 
         FIG. 9  illustrates a schematic diagram of a sensing configuration used to sense current from a power management integrated circuit (PMIC), in accordance with an embodiment; 
         FIG. 10  illustrates a schematic diagram of an operation configuration used to operate a display panel, in accordance with an embodiment; 
         FIG. 11  illustrates a schematic diagram of a single configuration system configured to sense electrical properties and to operate a display panel, in accordance with an embodiment; 
         FIG. 12  illustrates a block diagram of sensing scheme used to sense electrical properties from a PMIC, in accordance with an embodiment; 
         FIG. 13  illustrates example values that may occur in sensing using the sensing scheme of  FIG. 12 , in accordance with an embodiment; 
         FIG. 14  illustrates a flow diagram view of a process that may be used to measure and compensate for an ESR between a panel and a PMIC, in accordance with an embodiment; and 
         FIG. 15  illustrates a flow diagram of a process that may be used to measure and compensate for electrical parameters supplied from power circuitry to a display panel, in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS 
     One or more specific embodiments will be described below. 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. 
     Display panel performance may change with temperature and/or operating conditions of the display panel (e.g., current draw and/or locations of content). The display panel performance may change when an effective series resistance (ESR) changes between power circuitry and a display panel. This ESR change causes a current supplied to the display panel to drop. Using real-time measurements of the ESR may enable the display to appear more uniform across multiple different temperatures and/or operating conditions of the display. Furthermore, once the ESR is calculated, the current and/or voltage at an end of a route from the power circuitry to the display panel may be measured. When this current and/or voltage changes, the power circuitry may be driven differently to compensate for the change. For example, when the voltage across an organic light emitting diode (OLED) drops, a corresponding voltage (e.g., ELVDD or ELVSS) may be adjusted in a corresponding direction, such as increasing EVLDD and/or decreasing ELVSS, to achieve a target voltage across the OLED. 
     With the foregoing in mind and referring first to  FIG. 1 , an electronic device  10  according to an embodiment of the present disclosure may include, among other things, one or more processor(s)  12 , memory  14 , nonvolatile storage  16 , a display  18 , input structures  20 , an input/output (I/O) interface  22 , a power source  24 , and interface(s)  26 . The various functional blocks shown in  FIG. 1  may 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 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 electronic device  10 . 
     In the electronic device  10  of  FIG. 1 , the processor(s)  12  and/or other data processing circuitry may be operably coupled with the memory  14  and the nonvolatile storage  16  to perform various algorithms. Such programs or instructions, including those for executing the techniques described herein, executed by the processor(s)  12  may 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 memory  14  and the nonvolatile storage  16 . The memory  14  and the nonvolatile storage  16  may 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)  12  to enable the electronic device  10  to provide various functionalities. 
     In certain embodiments, the display  18  may be a liquid crystal display (e.g., LCD), which may allow users to view images generated on the electronic device  10 . In some embodiments, the display  18  may include a touch screen, which may allow users to interact with a user interface of the electronic device  10 . Furthermore, it should be appreciated that, in some embodiments, the display  18  may include one or more light emitting diode (e.g., LED) displays, or some combination of LCD panels and LED panels. The display  18  may include sensing circuitry  19  that is used to sense non-uniformity of the display  18  by sensing changes in voltage/current through thin-film transistors (TFTs) and/or emissive elements in the display  18 . 
     The input structures  20  of the electronic device  10  may enable a user to interact with the electronic device  10  (e.g., pressing a button to increase or decrease a volume level, a camera to record video or capture images). The I/O interface  22  may enable the electronic device  10  to interface with various other electronic devices. Additionally or alternatively, the I/O interface  22  may 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&#39;S LIGHTNING® connector, as well as one or more ports for a conducted RF link. 
     As further illustrated, the electronic device  10  may include the power source  24 . The power source  24  may 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 source  24  may be removable, such as a replaceable battery cell. 
     The interface(s)  26  enable the electronic device  10  to connect to one or more network types. The interface(s)  26  may 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)  26  may 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 device  10  may represent a block diagram of the notebook computer depicted in  FIG. 2 , the handheld device depicted in either of  FIG. 3  or  FIG. 4 , the desktop computer depicted in  FIG. 5 , the wearable electronic device depicted in  FIG. 6 , or similar devices. It should be noted that the processor(s)  12  and/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 device  10 . 
     In certain embodiments, the electronic device  10  may 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 device  10  in 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 device  10 , taking the form of a notebook computer  30 A, is illustrated in  FIG. 2  in accordance with one embodiment of the present disclosure. The depicted computer  30 A may include a housing or enclosure  32 , a display  18 , input structures  20 , and ports of the I/O interface  22 . In one embodiment, the input structures  20  (e.g., such as a keyboard and/or touchpad) may be used to interact with the computer  30 A, such as to start, control, or operate a GUI or applications running on computer  30 A. For example, a keyboard and/or touchpad may allow a user to navigate a user interface or application interface displayed on display  18 . 
       FIG. 3  depicts a front view of a handheld device  30 B, which represents one embodiment of the electronic device  10 . The handheld device  30 B 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 device  30 B may be a model of an IPOD® or IPHONE® available from APPLE INC. of Cupertino, Calif. 
     The handheld device  30 B may include an enclosure  32  to protect interior components from physical damage and to shield them from electromagnetic interference. The enclosure  32  may surround the display  18 , 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 interfaces  22  may open through the enclosure  32  and 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 structures  20 , in combination with the display  18 , may allow a user to control the handheld device  30 B. For example, a first input structure  20  may activate or deactivate the handheld device  30 B, one of the input structures  20  may navigate user interface to a home screen, a user-configurable application screen, and/or activate a voice-recognition feature of the handheld device  30 B, while other of the input structures  20  may provide volume control, or may toggle between vibrate and ring modes. Additional input structures  20  may also include a microphone that may obtain a user&#39;s voice for various voice-related features, and a speaker to allow for audio playback and/or certain phone capabilities. The input structures  20  may also include a headphone input (not illustrated) to provide a connection to external speakers and/or headphones and/or other output structures. 
       FIG. 4  depicts a front view of another handheld device  30 C, which represents another embodiment of the electronic device  10 . The handheld device  30 C may represent, for example, a tablet computer, or one of various portable computing devices. By way of example, the handheld device  30 C may be a tablet-sized embodiment of the electronic device  10 , which may be, for example, a model of an IPAD® available from APPLE INC. of Cupertino, Calif. 
     Turning to  FIG. 5 , a computer  30 D may represent another embodiment of the electronic device  10  of  FIG. 1 . The computer  30 D 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 computer  30 D may be an IMAC®, a MACBOOK®, or other similar device by APPLE INC. It should be noted that the computer  30 D may also represent a personal computer (e.g., PC) by another manufacturer. A similar enclosure  32  may be provided to protect and enclose internal components of the computer  30 D such as the display  18 . In certain embodiments, a user of the computer  30 D may interact with the computer  30 D using various peripheral input devices, such as a keyboard  37  or a mouse  38 , which may connect to the computer  30 D via an I/O interface  22 . 
     Similarly,  FIG. 6  depicts a wearable electronic device  30 E representing another embodiment of the electronic device  10  of  FIG. 1  that may be configured to operate using the techniques described herein. By way of example, the wearable electronic device  30 E, which may include a wristband  43 , may be an APPLE WATCH® by APPLE INC. However, in other embodiments, the wearable electronic device  30 E 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 display  18  of the wearable electronic device  30 E 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 device  30 E. 
     Although the following discusses sensing current through an OLED as a pixel, some embodiments may include measuring other parameters suitable for other pixel types. For example, LED voltage may be sensed at LED pixels in the display. 
       FIG. 7  illustrates a block diagram view of a display system  100 . The display system  100  includes a power unit  102  that includes a power management integrated circuit (PMIC)  104  that manages and provides power to a display panel  106  that includes one or more consumers  108  through a connection  110  (e.g., flex connector). For example, the consumers  108  may include multiple self-emissive units (e.g., organic light-emitting diodes OLED) that convert electrical power to emitted light. The power transmitted from the PMIC  104  is transmitted through one or more routes  112  that may each may include one or more contact points  114  and  116  that couple one or more components. For example, the contact points  114  and/or  116  may include a pad where components may be joined (e.g., soldered) and/or physically connected (e.g., couplers). However, the routes  112  and/or the contact points  114  and/or  116  may cause a change in resistivity between the PMIC  104  and the consumer  108 . Furthermore, this change in resistivity may also cause a change in a supplied current to the consumer  108 . This current drop may be attributed to resistances in the route  112  to the consumer  108 . For example,  FIG. 8  illustrates a schematic diagram of circuitry  130  having a self-emissive unit  131  (e.g., OLED). The PMIC  104  provides an ELVDD  132  and an ELVSS  134  to provide a provided voltage  135 . However, resistances  136  in the line may diminish a panel voltage  137  due to a voltage difference between a node  138  and ELVDD  132 . Furthermore, these resistances  136  at another end of the self-emissive unit  131  may cause a voltage difference between the ELVSS  134  and a voltage at a node  140 . In other words, the display panel voltage  137  (voltage difference between nodes  138  and  140 ) may be different than the provided voltage  135  due to Ohm&#39;s law properties. This change (e.g., drop) in voltage may cause a resultant change (e.g., drop) in current causing a change in emission of light by the self-emissive unit  131 . Furthermore, the resistances  136  may change with temperature of the display  18 . Accordingly, this current may be monitored using a measurement of V OLED    144  across the self-emissive unit  131 . In some embodiments, measurement of a current through the route  112  may be used to estimate/calculate and compensate for the V OLED    144  changes to reduce the impact on of the resistances  136  on the self-emissive unit  131  due to current drop. In some embodiments, monitoring the current may additionally or alternatively be used to measure an equivalent series resistance (ESR) of the route  112  between the PMIC  104  and the consumer  108 . 
       FIGS. 9 &amp; 10  illustrate a bi-configuration system that includes a first configuration for current sensing through the route  112  to determine current drop and a second configuration for regular operation.  FIG. 9  illustrates a sensing configuration  170  that is used to sense a current  171  between a PMIC  172  in power circuitry  174  through testing circuitry  176  including a current sensing unit  178 . The current  171  is passed at a supplied voltage  180  to a display panel  182 . The current  171  may be passed through intermediate connectors  184  (e.g., flex) between the power circuitry  174  and the display panel  182 . Furthermore, the testing circuitry  176 , the power circuitry  174 , the intermediate connectors  184 , and/or the display panel  182  may be connected to adjacent components using connectors  186  (e.g., board-to-board interfaces) that provide electrical connections through the various components. As illustrated, a switch  188  may remain open in the sensing configuration to force the current  171  through the current sensing unit  178  through low impedance paths  190 . 
     In an operation configuration  200 , illustrated in  FIG. 10 , the switch  188  is closed to form a low impedance path  202  bypassing the current sensing unit  178 . Additionally, the low impedance paths  190  may be switched to open using switches  204  to prevent the current  171  from passing through the current sensing unit  178 . However, this bi-configuration system utilizes external components that use additional connections that may increase a risk of desense condition where degradation of signals in the circuit occurs due to noise sources. 
     To alleviate such issues related to the bi-configuration system, a single configuration system  220 , illustrated in  FIG. 11 , may be utilized to provide operation and/or to sense a current  221  from power circuitry  222  to a panel  224 . The current  221  may be passed through intermediate components  226  via one or more connectors  228 . Furthermore, one or more paths  232  may be used to transport the current  221  and to sense a current and/or a voltage at a node  233  along a path  234  of the one or more paths  232 . The path  234  may be used to deliver the current. Other paths may be used to sample and determine various electrical properties at the node  233 . For example, a path  236  may be used to sample a current at the node  233 , and/or a path  238  may be used to sample a voltage at the node  233 . In some embodiments, sampling the current and/or voltage may include pumping in a signal with a known current and/or voltage to determine electrical properties at the node  233 . 
       FIG. 12  illustrates a sensing scheme  250  used to determine a voltage and/or current at the node  233  that may be used with the single configuration system  220  of  FIG. 11 . As illustrated, the sensing scheme  250  includes passing a current  252  through circuitry having an equivalent series resistance (ESR)  254  along the path  234 . Similarly, other paths  236  and  238  have ESRs  255  and  256 , respectively. The ESRs  254 ,  255 , and  256  may correspond to resistances in the paths  234 ,  236 , and  238 , respectively, along with any contact points occurring in the paths. In other words, the ESR  254  may correspond to an overall resistance through the path  234 . Similarly, the ESRs  255  and  256  may correspond to overall resistances through the paths  236  and  238 , respectively. In some embodiments, the ESRs  254 ,  255 , and/or  256  may at least partially fluctuate with temperature and/or other operating parameters of the display  18 . The current  252  is passed through the path having the ESR  254  to/from a voltage source  257  in a PMIC  258 . 
     The sensing scheme  250  may also utilize a current chopper  260  to provide a sensing current. The sensing current may be a modulated signal, such as a waveform  262 , that may be generated using the current chopper  260 . The frequency of the modulation of the sensing current may be set using a chopping frequency  266  that is input into the current chopper  260 . This chopping frequency  266  may be used to set the frequency of the waveform  262 . The chopping frequency  266  may be selected at a frequency (e.g., high frequency relative to a refresh rate of the display) that is determined to impact display quality of the display  18  less dramatically than other frequencies. For example, the chopping frequency  266  may be set according to panel results and/or may be set with a frequency that is above a detectability threshold of human perception. The chopping frequency  266  may also be selected to reduce and/or minimize possibility of synchronization of the sensing current with the PMIC  258 . The sensing current passes through a node  268  corresponding to the path  234  from a node  270  corresponding to the path  236 . However, in some embodiments, no current is passed through a node  272  of the path  238  due to the node  272  having a high impedance. Instead, the node  272  may be used to detect a voltage, such as a waveform  274 . This waveform  274  is then passed to a demodulator  276  that demodulates the waveform  274  using the chopping frequency  266  that is input to the demodulator  276  in addition to the current chopper  260 . This demodulation  276  results in a waveform  278 . This waveform  278  is then submitted to a high-pass filter  280  to obtain ESR MEAS    282 . The PMIC  258  also detects the voltage, as illustrated in waveform  274 , using a low pass filter  284 . This voltage, Vs, is passed to calculation circuitry  286  that receives the ESR MEAS    282  and the voltage. The calculation circuitry  286  divides the voltage by the ESR MEAS    282  to calculate a measured current  288  for the current  252 . 
     In other words, the sensing scheme  250  may be used to track the ESRMEAS  282  and the measured current  288  to provide for compensation of fluctuations of the operation of the display  18 .  FIG. 13  illustrates example values  300  that may occur during operation using the sensing scheme  250 . For example, an ESR  302  may fluctuate due to various operating parameters of the display, such as temperature of the path  234 . The changes to the ESR  302  may cause changes in current, as reflected in the current  304 . A modulated signal  306  may occur at an end of the path  234  at an opposite end of the path  234  from the PMIC  258 . As previously discussed, the signal  306  may be generated using the current chopper  260  and the chopping frequency  266  that is combined with the current  252 . The signal  306 , as previously discussed, is used to determine an ESR MEAS    308  and a measured current  310 . 
       FIG. 14  illustrates a process  350  that may be used to measure an ESR between a panel and a PMIC. Power circuitry provides a current over a first path between a panel and the power circuitry containing the PMIC (block  352 ). The current may be an operating current used to operate the display panel. The power circuitry also injects a sensing current via a second path from the power circuitry into the first path (block  354 ). For example, the sensing current may be injected into a node of the first path disposed at or adjacent to the display panel at an opposite end of the first path from the power circuitry. The sensing current may include a chopped current signal that is chopped at a frequency that may be selected to reduce or eliminate visibility of the injected sensing current on the display  18 . 
     The power circuitry measures an ESR of the first path using a third path from the power circuitry (block  356 ). For example, as previously discussed, the power circuitry may induce a combined signal combining the sensing current and the provided current. Knowing the injected sensing current, the power circuitry may extract a component corresponding to the sensing current to determine the ESR of the first path. The measured ESR may be used to compensate for electrical fluctuations from the power circuitry to the display panel (block  358 ). For example, by measuring the ESR, current drop between the display panel and the power circuitry may be tracked and compensated for. In other words, when the current drop increases, the provided current may be increased, but when the current drop decreases, the provided current may be decreased. 
       FIG. 15  illustrates a process  360  that may be used to measure electrical parameters supplied from power circuitry to a display panel. The power circuitry provides a current over a first path between a panel and the power circuitry (block  362 ). The current may be an operating current used to operate the display panel. The power circuitry also injects a sensing current via a second path from the power circuitry into the first path (block  364 ). For example, the sensing current may be injected into a node of the first path disposed at or adjacent to the display panel at an opposite end of the first path from the power circuitry. The sensing current may include a chopped current signal that is chopped at a frequency that may be selected to reduce or eliminate visibility of the injected sensing current on the display  18 . 
     The power circuitry measures an ESR of the first path using a third path from the power circuitry (block  366 ). For example, as previously discussed, the power circuitry may induce a combined signal combining the sensing current and the provided current. Knowing the injected sensing current, the power circuitry may extract a component corresponding to the sensing current to determine the ESR of the first path. 
     The power circuitry and/or the processor(s)  12  may be used to calculate supplied electrical parameters supplied via the first path at the display panel (block  368 ). The power circuitry and/or the processor(s)  12  may be used to compensate for the supplied electrical parameter fluctuations (block  370 ). For example, the power circuitry may utilize the combined signal to determine voltage levels in the first path at the display panel. In some embodiments, this voltage may be used compensate for fluctuations of the voltage and/or may be used to compute a current that is then used to compensate for current fluctuations. For example, the ESR and the voltage may be used to determine a current to the display panel, and the power circuitry and/or the processor(s) may be used to compensate for the current fluctuations. 
     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. Furthermore, it should be further understood that each of the embodiments disclosed above may be used with any and all of the other embodiments disclosed herein. The techniques presented and claimed herein are referenced and applied to material objects and concrete examples of a practical nature that demonstrably improve the present technical field and, as such, are not abstract, intangible or purely theoretical. Further, if any claims appended to the end of this specification contain one or more elements designated as “means for [perform]ing [a function] . . . ” or “step for [perform]ing [a function] . . . ”, it is intended that such elements are to be interpreted under 35 U.S.C. 112(f). However, for any claims containing elements designated in any other manner, it is intended that such elements are not to be interpreted under 35 U.S.C. 112(f).

Metadata:
Filing Date: 20180403
Publication Date: 20220111
Grant Date: 20220111
Priority Date: 20170908
Inventors: YOUN, SANG Y
CHANG, SUN-IL
Assignee: APPLE INC
CPC Classifications: [{"code": "G01R27/14", "inventive": true, "first": true, "tree": "[]"}, {"code": "G09G2320/041", "inventive": false, "first": false, "tree": "[]"}, {"code": "G01R27/14", "inventive": true, "first": true, "tree": "[]"}, {"code": "G01R27/14", "inventive": true, "first": true, "tree": "[]"}, {"code": "G09G2320/041", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 65631115