Patent Publication Number: US-11047734-B1

Title: System and method for measuring light sensor output in an electronic device

Description:
BACKGROUND 
     1. Technical Field 
     The present disclosure generally relates to electronic devices, and in particular to a system and method for measuring light sensor output in an electronic device. 
     2. Description of the Related Art 
     Personal electronic devices, such as cell phones, smartphones and other mobile devices enjoy widespread use in today&#39;s society. Smartphones can use liquid crystal displays (LCD) and organic light emitting diode (OLED) displays. OLED displays include an organic compound that emits light when an electrical current is applied. OLED displays can be designed in an edge to edge manner where the size of the OLED display is maximized to take up almost the entire front of the smartphone. 
     Smartphones frequently also include an ambient light sensor and a proximity sensor. The ambient light sensor measures the amount of ambient light present. The smartphone can dim or brighten the display based on the measured ambient light level to adjust the display brightness. A proximity sensor is a sensor able to detect the presence of nearby objects, without any physical contact with the object. Proximity sensors generally include an infrared (IR) emitter and IR light sensor. As one application, proximity sensors are used in smartphones to sense when the smartphone is near the face of a user, such as during a phone call, and trigger disabling of the touchscreen to prevent accidental taps on the touchscreen. Unfortunately, the use of ambient light sensors and proximity sensors with OLED displays causes problems. Light emitted from the OLED display interferes with light measurements by light sensors causing inaccurate measurements. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The description of the illustrative embodiments can be read in conjunction with the accompanying figures. It will be appreciated that for simplicity and clarity of illustration, elements illustrated in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements are exaggerated relative to other elements. Embodiments incorporating teachings of the present disclosure are shown and described with respect to the figures presented herein, in which: 
         FIG. 1  depicts an example mobile device within which various aspects of the disclosure can be implemented, according to one or more embodiments; 
         FIG. 2  is a schematic diagram of an example sensor circuit of a mobile device, according to one or more embodiments; 
         FIG. 3A  is a block diagram of example contents of the system memory of a mobile device configured to provide at least one of the novel features of the disclosure, according to one or more embodiments; 
         FIG. 3B  is a block diagram of example contents of a controller memory of a mobile device configured to provide at least one of the novel features of the disclosure, according to one or more embodiments; 
         FIG. 4A  is a side view of a display and ambient light sensor of a mobile device, according to one or more embodiments; 
         FIG. 4B  is a side view of a display and proximity sensor of a mobile device, according to one or more embodiments; 
         FIG. 5A  is an example circuit illustration of periodic synchronization and timing signals of a sensor circuit, according to one or more embodiments; and 
         FIG. 5B  is a timing diagram providing an example illustration showing details of a synchronization timer, according to one or more embodiments; and 
         FIG. 6  depicts a flowchart of a method of accurately measuring light sensor output in an electronic or mobile device with an OLED display, according to one or more embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     The illustrative embodiments provide a method, an electronic device, and a computer program product for measuring light sensor output in an electronic device. The method includes receiving, via a sensor circuit, periodic synchronization signals from a display of a device and generating one or more timing signals based on the received periodic synchronization signals. The method further includes tracking, via a counter, a number of the timing signals and, in response to each timing signal, recording output signals from a light sensor. The output signals correspond to a current light level detected by the light sensor. The method further includes accumulating the recorded output signals over a threshold number of timing signals. The method includes determining if a value of the counter is at least equal to or greater than the threshold number. The method still further includes, in response to determining that the value of the counter is at least equal to or greater than the threshold number, generating a composite output signal based on the accumulated recorded output signals. 
     According to another embodiment, an electronic device includes a display, a sensor circuit having a light sensor associated with the display, and at least one controller communicatively coupled to the display and the light sensor. The at least one controller receives periodic synchronization signals from the display and generates one or more timing signals, based on the received periodic synchronization signals. The at least one controller further tracks, via a counter, a number of timing signals, and in response to each timing signal, records output signals from the light sensor. The output signals correspond to a light level detected by the light sensor. The at least one controller further accumulates the recorded output signals over a threshold number of timing signals. The controller determines if a value of the counter is at least equal to or greater than the threshold number. The at least one controller further, in response to determining that the value of the counter is at least equal to or greater than the threshold number, generates a composite output signal based on the accumulated recorded output signals. 
     According to an additional embodiment, a computer program product includes a computer readable storage device and program code on the computer readable storage device. When executed within a processor associated with a device, the program code enables the device to provide the various functionality presented in the above-described method processes. 
     The above contains simplifications, generalizations and omissions of detail and is not intended as a comprehensive description of the claimed subject matter but, rather, is intended to provide a brief overview of some of the functionality associated therewith. Other systems, methods, functionality, features, and advantages of the claimed subject matter will be or will become apparent to one with skill in the art upon examination of the following figures and the remaining detailed written description. The above as well as additional objectives, features, and advantages of the present disclosure will become apparent in the following detailed description. 
     In the following description, specific example embodiments in which the disclosure may be practiced are described in sufficient detail to enable those skilled in the art to practice the disclosed embodiments. For example, specific details such as specific method orders, structures, elements, and connections have been presented herein. However, it is to be understood that the specific details presented need not be utilized to practice embodiments of the present disclosure. It is also to be understood that other embodiments may be utilized and that logical, architectural, programmatic, mechanical, electrical and other changes may be made without departing from the general scope of the disclosure. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present disclosure is defined by the appended claims and equivalents thereof. 
     References within the specification to “one embodiment,” “an embodiment,” “embodiments”, or “one or more embodiments” are intended to indicate that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. The appearance of such phrases in various places within the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Further, various features are described which may be exhibited by some embodiments and not by others. Similarly, various aspects are described which may be aspects for some embodiments but not other embodiments. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms “a”, “an”, and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. Moreover, the use of the terms first, second, etc. do not denote any order or importance, but rather the terms first, second, etc. are used to distinguish one element from another. 
     It is understood that the use of specific component, device and/or parameter names and/or corresponding acronyms thereof, such as those of the executing utility, logic, and/or firmware described herein, are for example only and not meant to imply any limitations on the described embodiments. The embodiments may thus be described with different nomenclature and/or terminology utilized to describe the components, devices, parameters, methods and/or functions herein, without limitation. References to any specific protocol or proprietary name in describing one or more elements, features or concepts of the embodiments are provided solely as examples of one implementation, and such references do not limit the extension of the claimed embodiments to embodiments in which different element, feature, protocol, or concept names are utilized. Thus, each term utilized herein is to be provided its broadest interpretation given the context in which that term is utilized. 
     Those of ordinary skill in the art will appreciate that the hardware components and basic configuration depicted in the following figures may vary. For example, the illustrative components within mobile device ( 100 ,  FIG. 1 ) are not intended to be exhaustive, but rather are representative to highlight components that can be utilized to implement the present disclosure. For example, other devices/components may be used in addition to, or in place of, the hardware depicted. The depicted example is not meant to imply architectural or other limitations with respect to the presently described embodiments and/or the general disclosure. 
     Within the descriptions of the different views of the figures, the use of the same reference numerals and/or symbols in different drawings indicates similar or identical items, and similar elements can be provided similar names and reference numerals throughout the figure(s). The specific identifiers/names and reference numerals assigned to the elements are provided solely to aid in the description and are not meant to imply any limitations (structural or functional or otherwise) on the described embodiments. 
       FIG. 1  depicts example mobile device  100  within which various aspects of the disclosure can be implemented, according to one or more embodiments. Examples of such mobile devices include, but are not limited to, a laptop computer, a notebook computer, a mobile phone, a digital camera, a tablet computer/device, and a smart-watch. The described features of the disclosure are also applicable to other devices with edge to edge screens or organic light emitting diode (OLED) displays, including but not limited to computer monitors and televisions. Thus, while the described embodiments refer specifically to mobile devices, it is appreciated that the references to mobile device is for example only and that the described features and functionalities apply equally to the other devices, which are not classified as mobile devices. Mobile device  100  includes processor  102 , which is communicatively coupled to storage device  104 , system memory  120 , display  130 , image capture device controller  134 , wireless communication radios  142   a - n , and other components described herein. 
     Mobile device  100  further includes storage device  104  and system memory  120 . System memory  120  may be a combination of volatile and non-volatile memory, such as random access memory (RAM) and read-only memory (ROM). System memory  120  can store program code or similar instructions associated with applications  122 , operating system  124 , firmware  128 , and display module  136 . Processor  102  loads and executes program code stored in system memory  120 . Examples of program code that may be loaded and executed by processor  102  include program code associated with applications  122  and display module  136 . 
     Display  130  can be one of a wide variety of display screens or devices, such as an OLED display. In the illustrated embodiments, display  130  is a touch screen device that includes a tactile, touch screen interface  131  that allows a user to provide tactile/touch input to or control mobile device  100  by touching the display screen. 
     In one embodiment, image capture device  132  is communicatively coupled to image capture device controller  134 , which is communicatively coupled to processor  102 . Image capture device  132  can capture images that are within the field of view of image capture device  132 . In one embodiment, image capture device  132  is a rear facing image capture device that faces the back or rear of housing  180 . 
     Radios  142   a - n  are coupled to antennas  148   a - n . Radios  142   a - n  and antennas  148   a - n  allow mobile device  100  to communicate wirelessly with external devices  152   a - n  via wireless network  150 . In one embodiment, external devices  152   a - n  can be radios (i.e., wireless signal transmitters and receivers) located at various cellular communication towers. 
     Mobile device  100  can further include data port  133 , which is connected with processor  102  and charging circuitry  135 . Charging circuitry  135  enables external charging of battery  143  via power input through data port  133 . Mobile device  100  further includes microphone  108 , one or more speakers  144 , and one or more physical buttons  107   a - n . Buttons  107   a - n  may provide controls for volume, power, and image capture device  132 . 
     Mobile device  100  further includes motion sensor(s)  161  that are communicatively coupled to processor  102 . Motion sensor(s)  161  can detect movement of mobile device  100  and provide motion data to processor  102  that indicate the spatial orientation and movement of mobile device  100 . Motion sensor(s)  161  can include one or more accelerometers  162  and gyroscope  163 . Accelerometers  162  measure linear acceleration of movement of mobile device  100  in multiple axes (X, Y and Z). In one embodiment, accelerometers  162  can include three accelerometers, where one accelerometer measures linear acceleration in the X axis, one accelerometer measures linear acceleration in the Y axis, and one accelerometer measures linear acceleration in the Z axis. Gyroscope  163  measures rotation or angular rotational velocity of mobile device  100 . 
     Mobile device  100  further includes additional components, such as global positioning system (GPS) module  164  and short-range communication component  147 . GPS module  164  can receive location and time data from GPS satellites. Short range communication component  147  is a low powered transceiver that wirelessly communicates with other wireless networks, such as with wireless access point  182 . Short range communication component  147  can be a variety of components, such as a near field communication (NFC) device, a Bluetooth device, or a wireless fidelity (Wi-Fi) device. In one embodiment, wireless network  150  can be a mobile phone base station and wireless access point  182  can be a Wi-Fi access point. Mobile device  100  further includes a housing  180  that contains the components of the mobile device. 
     Mobile device  100  further includes sensor circuit  190  and light sensor  192 . Sensor circuit  190  is also communicatively coupled to processor  102  and to light sensor  192  and display  130 . Sensor circuit  190  measures light sensor output from light sensor  192 , as will be described below. Light sensor  192  can be any of a variety of light sensors that sense a light level and provide an electrical output signal that is representative of the light level. In one embodiment, light sensor  192  can be an ambient light sensor (ALS) that measures the amount of ambient light present. In another embodiment, light sensor  192  can be a proximity sensor that detects the presence of nearby objects. In an additional embodiment, light sensor  192  can be an image capture device that is a front facing image capture device that faces the front of housing  180  and is mounted under or behind display  130 . 
     In the description of each of the following figures, reference is also made to specific components illustrated within the preceding figure(s). 
     With reference now to  FIG. 2 , a block diagram representation of one embodiment of sensor circuit  190  is shown. Sensor circuit  190  includes controller  210 , which is communicatively coupled to processor  102 , display  130 , controller memory  220 , synchronization timer  230 , switch(s)  232  and analog to digital converter (ADC)  236 . Sensor circuit  190  includes one or more switch(s)  232 , which are coupled to controller  210 , synchronization timer  230 , light sensor  192  and ADC  236 . Switch(s)  232  can include switches  232 A,  232 B and  232 C. Each of switch(s)  232 A-C can comprise one or more field effect transistors (FET). Synchronization timer  230  can toggle each of switches  232 A-C on (closed) and off (open). Switches  232 A-C are open when not closed. Sensor circuit  190  further includes capacitor  234 , which is coupled between switch(s)  232  and ADC  236 . Switch  232 B is coupled between light sensor  192  and capacitor  234  and is controlled by synchronization timer  230 . Switch  232 B periodically toggles or connects the light sensor output signals  280  of light sensor  192  to capacitor  234 . Switch  232 B is toggled by synchronization timer  230  to connect light sensor output signals  280  of light sensor  192  to capacitor  234 . Light sensor output signals  280  from light sensor  192  are analog signals. 
     Switch  232 A is coupled between capacitor  234  and ground  260  and is controlled by controller  210 . Switch  232 A is selectively toggled by controller  210  to connect capacitor  234  to ground  260  to enable discharge of capacitor  234  after a pre-determined number of light sensor output signals  280  have been recorded. Switch  232 C is coupled between light sensor  192  and ground  260  and is controlled by synchronization timer  230 . Switch  232 C is toggled by synchronization timer  230  to connect the output of light sensor  192  to ground  260  when capacitor  234  is not accumulating signals from the light sensor. According to one aspect, when the light sensor output signals  280  are not being accumulated by capacitor  234 , light sensor  192  is coupled to ground  260 , via switch  232 C. Coupling light sensor  192  to ground  260  when light sensor output signals  280  are not being accumulated prevents any parasitic capacitance from building charge on capacitor  234  during non-measurement times. Capacitor  234  accumulates light sensor output signals  280  when switch  232 B is toggled to a closed position to connect light sensor  192  to capacitor  234 . In one embodiment, sensor circuit  190  can be implemented as an application specific integrated circuit (ASIC). 
     Display  130  periodically generates a vertical synchronization waveform or signal (Vsync)  240  that is transmitted to controller  210 . Vsync signal  240  is an electrical signal that prevents screen tearing. Screen tearing occurs when the display  130  and processor  102  work independently, so new frames may be partially rendered when the display shows a frame. In response to Vsync signal  240 , processor  102  waits for the display to signal that the display is ready for the next display frame to ensure all displayed frames are always fully drawn. 
     During operation of display  130 , there are small periods of time when display pixels are not being updated and light is not being emitted from the display. This is called blanking or blank time. If the display  130  is driven by a pulse width modulation (PWM) signal, the blank time occurs during PWM off periods. The blank time period is synchronized to occur a pre-determined amount of time after the Vsync signal  240 . Accordingly, one feature of this disclosure is that Vsync signal  240  can be used to determine when display  130  is blank or the blank time of display  130 . 
     With reference now to  FIG. 3A , one embodiment of example contents of system memory  120  of mobile device  100  is shown. System memory  120  includes data, software, and/or firmware modules, including applications  122 , operating system  124 , firmware  128 , display module  136 , and composite output signal  310 . Display module  136  enables processor  102  to at least partially control the operation of display  130  including dimming and brightening display  130  based on composite output signal  310  received from sensor circuit  190 . Composite output signal  310  is received by processor  102  from sensor circuit  190  and stored to system memory  120 . Composite output signal  310  is the accumulated electrical light sensor output signals  280  from light sensor  192  that has been accumulated over several blank time periods. Composite output signal  310  can be used by processor  102 , executing display module  136 , to perform various functions such as dimming and brightening display  130  in response to ambient light levels. 
     With reference now to  FIG. 3B , one embodiment of example contents of controller memory  220  of sensor circuit  190  is shown. Controller memory  220  includes data, software, and/or firmware modules, including measuring module  320 . Measuring module  320  enables the measurement of light sensor output signals  280  from light sensor  192  during time periods when display  130  is off or blank. Light sensor  192  detects an amount of received light and generates corresponding electrical light sensor output signals  280 . Measuring module  320  enables recording and accumulating light sensor output during time periods when display  130  is blank. In one embodiment, measurement module  320  enables controller  210  and sensor circuit  190  to perform the processes presented in the flowchart of  FIG. 6 , as will be described below. 
     Controller memory  220  further includes counter  330 , counter threshold  332 , timing signals  334 , time period  336  and composite output signal  310 ′. Counter  330  tracks a number of timing signals  334  that are generated by processor  102 . Counter threshold  332  is a threshold number of timing signals  334 . Timing signals  334  are pulse width modulated signals that are periodically generated with a pre-determined delay after Vsync signal  240  is received. Time period  336  is an amount of time that switch  232 B is toggled to an ON state to connect light sensor  192  to capacitor  234 . Time period  336  corresponds to an amount of time that display  130  is blank. Each timing signal  334  is used to toggle switch  232 B, in order to connect light sensor  192  to capacitor  234  to allow transfer of the light sensor output signals  280  from light sensor  192  to be stored in capacitor  334  as a corresponding amount of energy. In response to counter  330  reaching a value that is greater than or equal to counter threshold  332 , controller  210  triggers ADC  236  to measure the charge stored by capacitor  234  and coverts the measured charge into a digital value that is stored in controller memory  220  as composite output signal  310 ′. Controller  210  transmits composite output signal  310 ′ to processor  102 . 
       FIG. 4A  illustrates an example of an organic light emitting diode (OLED) display  410  with an ambient light sensor  420  and an image capture device  430 . OLED display  410  is an example of display  130  in mobile device  100  of  FIG. 1 . OLED display  410  has a front surface  412  and a back or rear surface  414 . Front surface  412  faces and is viewed by a user of mobile device  100 . Light sensors, such as ambient light sensor  420  and image capture device  430  are mounted adjacent to back surface  414 . During operation, ambient light  422  passes through OLED display  410 , where the ambient light is detected by ambient light sensor  420 . Ambient light sensor  420  generates an electrical signal that is proportional to the level or intensity of ambient light  422 . Similarly, during operation, image light  424  passes through OLED display  410  where the image light  424  is detected by image capture device  430 . Image light  424  is the light reflected off an image that would be captured by image capture device  430 . Image capture device  430  generates electrical signals representative of image light  424 . 
     According to one aspect of the disclosure, because emitted light  426  from OLED display  410  interferes with light measurements by an ambient light sensor  420  and image sensing by image capture device  430 , operating ambient light sensor  420  and image capture device  430  when OLED display  410  is blank (i.e., not illuminated or emitting light) improves the accuracy of light measurements and image sensing. 
       FIG. 4B  illustrates an example of an organic light emitting diode (OLED) display  410 , with proximity sensor  440 . OLED display  410  is an example of display  130  of mobile device  100  of  FIG. 1 . Light sensors such as proximity sensor  440  are mounted adjacent to the back surface  414 . Proximity sensor  440  includes an infrared emitter (IRE)  442  and an infrared sensor (IRS)  444 . During operation, infrared emitter  442  generates and transmits infrared light  460  (hereinafter transmitted infrared light  460 ) that passes through OLED display  410 . Transmitted infrared light  460  is reflected off nearby surface  470  of an object as reflected infrared light  462 . Reflected infrared light  462  passes through OLED display  410  and is detected by an infrared sensor  444 . Proximity sensor  440  generates an electrical signal that is proportional to the level or intensity of reflected infrared light  462 . The intensity of reflected infrared light  462  is proportional to the distance of nearby surface  470 . Proximity sensor  440  is used to determine if OLED display  410  is in close proximity to nearby surface  470 . 
     According to one aspect of the disclosure, because transmitted infrared light  460  can interfere with the illumination of pixels in OLED display  130 , proximity light measurement cycles are synchronized to the display and limited in power and duration, resulting in limited sensitivity for each measurement cycle. Operating proximity sensor  440  using multiple independently synchronized and accumulated light measurement cycles improves the accuracy and sensitivity of proximity sensor measurements. 
     In one embodiment, controller  210 , executing measuring module  320 , receives periodic synchronization signals (i.e., Vsync  240 ) from display  130  of mobile device  100  and generates one or more timing signals  334 , based on the received periodic synchronization signals. Controller  210  tracks, via counter  330 , a number of the timing signals and, in response to each timing signal, records output signals from light sensor  192  and increments counter  330 . The light sensor output signals  280  from light sensor  192  are proportional to a light level detected by light sensor  192 . Controller  210  triggers sensor circuit  190  to accumulate the recorded output signals over a threshold number of timing signals and determines if a value of counter  330  is at least equal to or greater than counter threshold  332 . In response to determining that the value of counter  330  is at least equal to or greater than counter threshold  332 , controller  210 , causes sensor circuit  190  to generate a composite output signal  310 ′, based on the accumulated recorded output signals. The composite output signal  310 ′ is transmitted by controller  210  to processor  102 . 
     Turning to  FIG. 5A , details of synchronization timer  230  are shown. Synchronization timer  230  includes delay timers  510 ,  512 ,  514  and  516  (collectively delay timers  510 - 516 ). Each of the delay timers  510 - 516  has an input coupled to Vsync  240  (via controller  210 ) and an output coupled to the input of OR gate  530 . The output of OR gate  530  is coupled to switch  232 B. 
     With additional reference to  FIG. 5B , timing diagram  500  is shown. Timing diagram  500  shows several signals versus time within sensor circuit  190 . Timing diagram  500  includes Vsync signals  240 , which are periodically generated by display  130 . Timing diagram  500  includes timing signals  334  generated by controller  210 . Timing diagram  500  further includes time periods  336  when light sensor output signals  280  from the light sensor  192  are accumulated. In one embodiment, Vsync signal  240  can have a frequency of 90 hertz. In response to Vsync signal  240  from controller  210 , each delay timer  510 - 516  generates timing signals  334  that are delayed by an increasing amount of time from Vsync signal  240 . Delay timer  510  generates timing signal D 1 . Delay timer  512  generates timing signal D 2 . Delay timer  514  generates timing signal D 3 , and delay timer  516  generates timing signal D 4 . In one embodiment, the timing signals  334  can have a frequency of 360 hertz. 
     Each timing signal D 1 , D 2 , D 3  and D 4 , provides an output via OR gate  530  that is coupled to switch  232 B input and used to toggle switch  232 B to an on state (e.g., open state) in order to connect the output of light sensor  192  ( FIG. 2 ) to capacitor  234  ( FIG. 2 ) and thus record and accumulate output signals from light sensor  192 . Switch  232 B toggles on to transfer the output of light sensor  192  to capacitor  234  during time periods  336  when display  130  is blank. In other words, time periods  336  are time windows during which light sensor output can be accumulated without interference from the operation of display  130 . After a pre-determined number of timing signals  334  (i.e., counter threshold  332 ), ADC  236  ( FIG. 2 ) can be triggered to generate composite output signal  310 ′ from the recorded and accumulated output signals on capacitor  234 . In one embodiment, counter threshold  332  can have a value of three timing signals such that light sensor output signals  280  of light sensor  192  is recorded and accumulated at capacitor  234  for three time periods  336 , before ADC  236  generates composite output signal  310 ′. 
       FIG. 6  depicts a method  600  for measuring light sensor output in an electronic device. The description of method  600  will be described with reference to the components and examples of  FIGS. 1-5B . The operations depicted in  FIG. 6  can be performed by mobile device  100  or other suitable devices configured with one or more light sensors. One or more of the processes of the methods described in  FIG. 6  may be performed by a controller (e.g., controller  210 ) of mobile device  100  executing program code associated with measuring module  320 . 
     Method  600  begins at start block  602 . At block  604 , controller  210  initializes counter  330  by setting counter  330  to a value of zero. Controller  210  retrieves counter threshold  332  and time period  336  from controller memory  220  (block  606 ). Controller  210  receives Vsync signal  240  from display  130  (block  608 ). Controller  210  triggers synchronization timer  230  to generate one or more timing signals  334  based on Vsync signal  240  (block  610 ). For each timing signal  334 , controller  210  increments counter  330  (block  612 ). Controller  210  causes switch  232 B to toggle in response to each timing signal  334  (block  614 ). For each timing signal  334 , controller  210  causes switch  232 B to remain closed for time period  336  and then opens. After time period  336  ends, controller  210  causes synchronization timer  230  to toggle switch  232 C to connect the output of light sensor  192  to ground  260  when capacitor  234  is not accumulating signals from the light sensor. 
     In one embodiment, controller  210  passes Vsync signal  240  to synchronization timer  230  to use in the generation of timing signals  334 . As switch  232 B is toggled on, output signals from light sensor  192  are connected to capacitor  234  where the light sensor output signals  280  (i.e., value of sensed ambient light level) are stored and accumulated (block  616 ). Switch  232 B connects capacitor  234  to the output of light sensor  192  when display  130  is blank (i.e., during each time period  336 ). The charge on capacitor  234  increases each time switch  232 B is toggled on while there is light detected by sensor  192 . The light sensor output signals  280  from light sensor  192  correspond to a light level (which is sensed as indicative of ambient light) detected by the light sensor  192 . 
     At decision block  618 , controller  210  determines if the value of counter  330  is greater than or equal to the value of counter threshold  332 . In response to determining that the value of counter  330  is not greater than or equal to the value of counter threshold  332 , controller  210  continues to trigger synchronization timer  230  to generate one or more timing signals  334  based on Vsync signal  240  (block  610 ). In response to determining that the value of counter  330  is greater than or equal to (&gt;) the value of counter threshold  332 , controller  210  triggers ADC  236  to sense the accumulated output signals (i.e., charge) on capacitor  234  (block  620 ) and to generate a digital composite output signal  310 ′ corresponding to the measured accumulated output signals (block  622 ). Controller  210  transmits composite output signal  310 ′ to processor  102  (block  624 ). Controller  210  clears the accumulated output signals by discharging capacitor  334 . As provided at block  626 , controller  210  causes switch  232 A to toggle to a position which connects capacitor  234  to ground  260  in order to discharge capacitor  334  (block  626 ). Method  600  then terminates at end block  630 . 
     According to one aspect of the disclosure, because light emitted from OLED display  410  interferes with light measurements by light sensor  192 , operating light sensor  192  when OLED display  410  is blank improves the accuracy of light measurements. 
     According to another aspect of the disclosure, because each individual time period  336  (during which display  130  is blank or off) is shorter than the time needed to collect enough analog light sensor output signals for ADC  236  to digitize, light sensor output signals  280  from light sensor  192  are recorded and accumulated over multiple time periods  336 . The accumulation of light sensor output signals  280  for multiple time periods  336  allows the collection of enough analog light sensor output signals for ADC  236  to digitize. 
     In the above-described method of  FIG. 6 , one or more of the method processes may be embodied in a computer readable device containing computer readable code such that operations are performed when the computer readable code is executed on a computing device. In some implementations, certain operations of the methods may be combined, performed simultaneously, in a different order, or omitted, without deviating from the scope of the disclosure. Further, additional operations may be performed, including operations described in other methods. Thus, while the method operations are described and illustrated in a particular sequence, use of a specific sequence or operations is not meant to imply any limitations on the disclosure. Changes may be made with regards to the sequence of operations without departing from the spirit or scope of the present disclosure. Use of a particular sequence is therefore, not to be taken in a limiting sense, and the scope of the present disclosure is defined only by the appended claims. 
     Aspects of the present disclosure are described above with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the disclosure. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. Computer program code for carrying out operations for aspects of the present disclosure may be written in any combination of one or more programming languages, including an object-oriented programming language, without limitation. These computer program instructions may be provided to a processor of a general-purpose computer, special-purpose computer, or other programmable data processing apparatus to produce a machine that performs the method for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks. The methods are implemented when the instructions are executed via the processor of the computer or other programmable data processing apparatus. 
     As will be further appreciated, the processes in embodiments of the present disclosure may be implemented using any combination of software, firmware, or hardware. Accordingly, aspects of the present disclosure may take the form of an entirely hardware embodiment or an embodiment combining software (including firmware, resident software, micro-code, etc.) and hardware aspects that may all generally be referred to herein as a “circuit,” “module,” or “system.” Furthermore, aspects of the present disclosure may take the form of a computer program product embodied in one or more computer readable storage device(s) having computer readable program code embodied thereon. Any combination of one or more computer readable storage device(s) may be utilized. The computer readable storage device may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of the computer readable storage device can include the following: a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer readable storage device may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. 
     Where utilized herein, the terms “tangible” and “non-transitory” are intended to describe a computer-readable storage medium (or “memory”) excluding propagating electromagnetic signals; but are not intended to otherwise limit the type of physical computer-readable storage device that is encompassed by the phrase “computer-readable medium” or memory. For instance, the terms “non-transitory computer readable medium” or “tangible memory” are intended to encompass types of storage devices that do not necessarily store information permanently, including, for example, RAM. Program instructions and data stored on a tangible computer-accessible storage medium in non-transitory form may afterwards be transmitted by transmission media or signals such as electrical, electromagnetic, or digital signals, which may be conveyed via a communication medium such as a network and/or a wireless link. 
     The description of the present disclosure has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the disclosure in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope of the disclosure. The described embodiments were chosen and described in order to best explain the principles of the disclosure and the practical application, and to enable others of ordinary skill in the art to understand the disclosure for various embodiments with various modifications as are suited to the particular use contemplated. 
     As used herein, the term “or” is inclusive unless otherwise explicitly noted. Thus, the phrase “at least one of A, B, or C” is satisfied by any element from the set {A, B, C} or any combination thereof, including multiples of any element. 
     While the disclosure has been described with reference to example embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the disclosure. In addition, many modifications may be made to adapt a particular system, device, or component thereof to the teachings of the disclosure without departing from the scope thereof. Therefore, it is intended that the disclosure not be limited to the particular embodiments disclosed for carrying out this disclosure, but that the disclosure will include all embodiments falling within the scope of the appended claims.