PATENT DOCUMENT

Publication Number: US-9064451-B2
Application Number: US-201213364100-A
Country: US
Kind Code: B2

Title: Organic light emitting diode display having photodiodes

Abstract:
Systems, methods, and devices are provided in which photodetectors disposed throughout a display are used to control the display brightness. The photodetectors are to be used for ambient light sensing, proximity sensing, or to compensate for aging OLEDs. In some embodiments, photodiodes are fabricated with OLEDs during the TFT fabrication process. In some embodiments, the photodetectors may be disposed throughout the display in zones containing OLEDs. The photodetectors are used to control the display brightness and color for the OLEDs in areas around each photodetector based on ambient light, aging, and/or nearby objects. A controller makes driving strength adjustments to the OLEDs in each zone independent of other zones. Photodetectors disposed throughout the display may improve proximity sensing and provide additional functionality to the device.

Claims:
What is claimed is: 
     
       1. An electronic device, comprising:
 a housing; 
 a processor disposed within the housing; 
 one or more input structures configured to transmit input signals to the processor; and 
 a display, comprising a display screen and a controller, the display screen being coupled to the housing,
 the display screen comprising:
 a plurality of organic light emitting diodes (OLEDs) disposed across the display screen, wherein each OLED of the plurality of OLEDs emits light in response to control signals; and 
 a plurality of photodetectors disposed across the display screen, wherein the plurality of photodetectors are configured to detect light and generate signals relating to the detected light, wherein at least a portion of the plurality of photodetectors is arranged to detect ambient light incident to the display screen; and 
 
 the controller configured to determine the control signals for the plurality of OLEDs based at least in part on the signals relating to the detected light so as to compensate for differences in ambient light conditions on the display screen, wherein the control signals comprise a first control signal that provides compensation to a first OLED in the plurality of OLEDs and a second control signal that provides compensation to a second OLED in the plurality of OLEDs, wherein the first compensation is based on the detected light in a first region of the display screen, wherein the second compensation is based on the detected light in a second region of the display screen, and wherein the first compensation is different than the second compensation. 
 
 
     
     
       2. The electronic device of  claim 1 , wherein the plurality of OLEDs and the plurality of photodetectors are disposed on a common layer of the display screen. 
     
     
       3. The electronic device of  claim 1 , wherein the plurality of OLEDs is disposed on a layer of the display screen and the plurality of photodetectors is disposed on a different layer of the display screen. 
     
     
       4. The electronic device of  claim 1 , wherein each OLED of the plurality of OLEDs is disposed across the display screen with a respective photodetector of the plurality of photodetectors in a substantially 1:1 ratio, and the controller is configured to determine the control signals for each OLED based at least in part on the signals relating to the detected light from the respective photodetector. 
     
     
       5. The electronic device of  claim 1 , wherein the display screen comprises a plurality of zones, wherein each zone of the plurality of zones comprises at least two OLEDs of the plurality of OLEDs and at least one photodetector of the plurality of photodetectors, and the controller is configured to determine the control signals for the at least two OLEDs of each zone based at least in part on the signals relating to the detected light from the at least one photodetector of that zone. 
     
     
       6. The electronic device of  claim 1 , wherein the controller is configured to adjust a brightness of the plurality of OLEDs in a portion of the display screen based at least in part on differences in the detected ambient light incident to the portion of the display screen and detected ambient light incident to a remainder of the display screen. 
     
     
       7. The electronic device of  claim 1 , wherein the controller determines the control signals for the plurality of OLEDs based at least in part on a comparison of the detected light with calibration curves, algorithms, or charts, or combinations thereof. 
     
     
       8. The electronic device of  claim 1 , wherein at least some of the plurality of photodetectors are disposed about the periphery of the display screen and are configured to detect an object near the display screen and generate signals relating to the object, wherein the controller is configured to determine the control signals for the plurality of OLEDs based at least in part on the signals relating to the object. 
     
     
       9. The electronic device of  claim 1 , wherein the one or more input structures comprise a touch screen of the display screen. 
     
     
       10. The electronic device of  claim 1 , wherein at least some of the photodetectors are disposed between at least some of the OLEDs. 
     
     
       11. The electronic device of  claim 1  wherein the differences in ambient light conditions on the display screen comprise first ambient light conditions in a first region of the display screen and second first ambient light conditions in a second region of the display screen, wherein the first and second ambient light conditions are different, and wherein the controller is configured to determine the control signals for the plurality of OLEDs so as to compensate for the differences between the first and second ambient light conditions. 
     
     
       12. The electronic device of  claim 1  wherein the differences in ambient light conditions on the display screen comprise first ambient light conditions in a first region of the display screen and second first ambient light conditions in a second region of the display screen, wherein the first and second ambient light conditions are different, wherein the controller is configured to provide first adjustments to the control signals of the OLEDs in the first region and second adjustments to the control signals of the OLEDs in the second region, and wherein the first and second adjustments are different and the differences between the first and second adjustments compensate for the differences between the first and second ambient light conditions. 
     
     
       13. The electronic device of  claim 1  wherein the plurality of OLEDs and the plurality of photodetectors are both disposed evenly inside the display screen. 
     
     
       14. An electronic device, comprising:
 a housing; 
 a processor disposed within the housing; 
 one or more input structures configured to transmit input signals to the processor; and 
 a display, comprising a display screen and a controller, the display screen being coupled to the housing,
 the display screen comprising:
 a plurality of organic light emitting diodes (OLEDs) disposed across the display screen, wherein each OLED of the plurality of OLEDs emits light in response to control signals; and 
 a plurality of photodetectors disposed across the display screen, wherein the plurality of photodetectors are configured to detect light and generate signals relating to the detected light, wherein at least a portion of the plurality of photodetectors is arranged to detect ambient light incident to the display screen; and 
 
 the controller configured to determine the control signals for the plurality of OLEDs based at least in part on the signals relating to the detected light so as to compensate for differences in ambient light conditions on the display screen, wherein the detected light comprises light emitted by the plurality of OLEDs, and the controller is configured to determine the control signals for the plurality of OLEDs based at least in part on the detected emitted light by the OLEDs and an age of the OLEDs. 
 
 
     
     
       15. The electronic device of  claim 14 , wherein the determined controls signals for the plurality of OLEDs compensate a color and a brightness for each OLED. 
     
     
       16. A display, comprising:
 a plurality of organic light emitting diodes (OLEDs) disposed on a common layer across the display, wherein each OLED of the plurality of OLEDs emits light in response to control signals; 
 a plurality of photodetectors disposed on the common layer across the display screen, wherein the plurality of photodetectors are configured to detect light and generate signals relating to the detected light, wherein at least a portion of the plurality of photodetectors is arranged to detect ambient light incident to the display; and 
 a controller configured to determine the control signals for the plurality of OLEDs based at least in part on the signals relating to the detected light so as to compensate for differences in ambient light conditions across the display, wherein a first group of OLEDs in the plurality of OLEDs is compensated differently than a second group of OLEDs in the plurality of OLEDs to compensate for the differences in ambient light conditions across the display. 
 
     
     
       17. The display of  claim 16 , wherein each OLED of the plurality of OLEDs is disposed across the display with a respective photodetector of the plurality of photodetectors in a substantially 1:1 ratio, and the controller is configured to determine the control signals for each OLED based at least in part on the signals relating to the detected light from the respective photodetector. 
     
     
       18. The display of  claim 16 , wherein the display comprises a plurality of zones, wherein each zone of the plurality of zones comprises at least two OLEDs of the plurality of OLEDs and at least one photodetector of the plurality of photodetectors, and the controller is configured to determine the control signals for the at least two OLEDs of each zone based at least in part on the signals relating to the detected light from the at least one photodetector of that zone. 
     
     
       19. The display of  claim 18 , wherein each zone of the plurality of zones comprises OLEDs of the plurality of OLEDs configured to emit light of complementary colors. 
     
     
       20. The display of  claim 16 , wherein the controller is configured to adjust a brightness of the plurality of OLEDs in a portion of the display based at least in part on differences in the detected ambient light incident to the portion of the display and detected ambient light incident to a remainder of the display. 
     
     
       21. The display of  claim 16 , wherein the detected light comprises light emitted by the plurality of OLEDs, and the controller is configured to determine the control signals for the plurality of OLEDs based at least in part on the detected emitted light by the OLEDs and an age of the OLEDs. 
     
     
       22. The electronic device of  claim 16 , wherein the controller determines the control signals for the plurality of OLEDs based at least in part on a comparison of the detected light with calibration curves, algorithms, or charts, or combinations thereof. 
     
     
       23. The display of  claim 16 , wherein at least some of the plurality of photodetectors are disposed about the periphery of the display and are configured to detect an object near the display and generate signals relating to the object, wherein the controller is configured to determine the control signals for the plurality of OLEDs based at least in part on the signals relating to the object. 
     
     
       24. The display of  claim 23 , wherein the controller is configured to turn off at least some of the plurality of OLEDs based at least in part on the signals relating to the object. 
     
     
       25. A method of manufacturing a display, comprising:
 arranging a plurality of organic light emitting diodes (OLEDs) across a display; 
 configuring the plurality of OLEDs to emit light in response to control signals; 
 arranging a plurality of photodetectors across the display to detect light emitted by the plurality of OLEDs; 
 arranging at least a portion of the plurality of photodetectors to detect ambient light incident to display; and 
 configuring a controller to determine the control signals based at least in part on ambient light detected by at least the portion of the plurality of photodetectors so as to compensate for differences in ambient light conditions on different regions of the display, wherein a first OLED in the plurality of OLEDs is compensated based on detected light in a first region of the display, wherein a second OLED in the plurality of OLEDs is compensated based on detected light in a second region of the display, and wherein the first and second OLEDs are compensated differently to compensate for a difference between the detected light in the first region of the display and the detected light in the second region of the display. 
 
     
     
       26. The method of  claim 25 , wherein the plurality of OLEDs and the plurality of photodetectors are arranged on a common layer of the display. 
     
     
       27. The method of  claim 25 , comprising configuring the controller to adjust a brightness of the plurality of OLEDs in a portion of the display screen based at least in part on differences in the detected ambient light incident to the portion of the display and detected ambient light incident to a remainder of the display. 
     
     
       28. The method of  claim 25 , comprising configuring the controller to determine the control signals based at least in part on the detected emitted light by the plurality of OLEDs and an age of the plurality of OLEDs. 
     
     
       29. The method of  claim 25 , comprising arranging the plurality of OLEDs and the plurality of photodetectors in a plurality of zones, wherein each zone of the plurality of zones comprises at least two OLEDs of the plurality of OLEDs and at least one photodetector of the plurality of photodetectors; and
 configuring the controller to determine the control signals for the at least two OLEDs of each zone based at least in part on the emitted light detected and ambient light detected. 
 
     
     
       30. A method of driving organic light emitting diodes (OLEDs) in a display, comprising driving a plurality of OLEDs disposed across the display to emit light at a respective plurality of drive strengths;
 detecting light by a plurality of photodetectors disposed across the display, wherein at least some of the detected light is ambient light incident on the display; 
 determining a difference between ambient light incident on a first region of the display and ambient light incident on a second region of the display; 
 adjusting the plurality of drive strengths for the plurality of OLEDs based at least in part on the difference. 
 
     
     
       31. The method of  claim 30 , comprising adjusting the plurality of drive strengths based at least in part on detected light emitted by the plurality of OLEDs. 
     
     
       32. The method of  claim 30 , comprising detecting an object near the display; and
 adjusting the plurality of drive strengths based at least in part on the detected object. 
 
     
     
       33. The method of  claim 30 , comprising adjusting the plurality of drive strengths to produce a uniform display appearance. 
     
     
       34. The method of  claim 30 , wherein adjusting the plurality of drive strengths for the plurality of OLEDs compensates a color, or a brightness, or a combination thereof of each respective OLED.

Description:
BACKGROUND 
     The present disclosure relates generally to electronic displays and, more particularly, to photodetectors in a 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 and systems increasingly include display screens as part of the user interface of the device or system. As may be appreciated, display screens may be employed in a wide array of devices and systems, including desktop computer systems, notebook computers, and handheld computing devices, as well as various consumer products, such as cellular phones, televisions, and portable media players. 
     To display images, videos, and user interfaces, displays use arrays of pixels, each pixel having multiple colors. Primary colors of light (e.g., red, green, and blue) may be combined in each pixel to create many other colors, including white. Controllers drive pixels with coordinated instructions to create an image on the display. Some displays involve illuminating a backlight through a light-modulating liquid crystal layer (e.g., typical liquid crystal displays) while others involve directly illuminating each pixel to a desired intensity (e.g., organic light emitting diode (OLED) displays). 
     Because each OLED may emit its own colored light, OLED displays may be thinner and lighter than displays requiring a backlight. OLEDs may also be desirable because they may be fabricated on flexible or rigid substrates. OLED displays may also allow better viewing angles and better color than some liquid crystal displays (LCDs). 
     However, displays do not always operate in the same lighting environments. The perception of emitted light from a display may be affected by lighting conditions. Changing the brightness of a display can improve the perceived image of the display. For example, a dim display may provide sufficient visibility in dark environments, while a bright display may provide better visibility in a bright environment. However, controlling the brightness of a display to improve display visibility may not always be as straightforward as changing the brightness of the entire display according to a single measurement of the environmental light. For example, the ambient light on a display may not be uniform across the display, and displays are frequently moved such that their surrounding environment is dynamic. 
     Furthermore, the appearance of OLED displays may not remain constant indefinitely. As OLED displays age through use, their brightness and/or color may change. Some OLEDs, particularly blue OLEDs, age more quickly than others, which may change the appearance of the display. Over time as the OLEDs age, images shown on parts of the display may appear much different from the intended image. OLED controllers may make changes to compensate for such shifts in brightness and color. However, aging may occur differently across a display. For example, aging may occur in an unpredictable manner due to the manner in which end users use the device. 
     Further, OLED displays may be used on many mobile devices, including cellular phones and such. OLED displays may also be touch-sensitive. Presently, it is desirable to utilize a proximity sensor to turn off the display when a user places the phone near the user&#39;s face. This both saves power and prevents undesired inputs to the touch screen. However, such proximity sensors are typically placed outside of the display area, thus creating some inaccuracies when turning the display on and off. 
     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. 
     Embodiments of the present disclosure relate to OLED displays and methods to adjust OLED displays to maintain a desired appearance. Photodetectors may be disposed in the OLED display with individual OLEDs or zones of OLEDs to adjust their emitted light. In an embodiment, each photodetector may detect light incident to the display. Such detected light may be from OLEDs of the display, from the ambient light, or both. Ambient light may affect how the light emitted from the display is perceived. For example, a corner portion of the display may be in a shadow while the remainder is under a bright light. If all the OLEDs are set to the same brightness and/or color level, either the shaded corner or the remainder of the display may be less visible than the other. The photodetectors may enable controllers to brighten or dim the entire display and/or compensate each OLED or group of OLEDs (e.g., OLEDs in the corner portion) to improve the appearance of the display as a whole. This may improve the versatility of the display in different operating environments. 
     In other embodiments, each OLED may be adjacent to a photodetector to measure the aging characteristics of that particular OLED. Aged OLEDs may emit light different from less aged OLEDs, which may result in a poor display quality for unevenly aged displays. For example, if all the blue OLEDs in a region of the display have aged more than the red and green OLEDs, that region of the display may appear dimmer and/or more yellow than desired. As portions of the display age at different rates, the quality of a displayed image may decrease. By adjusting the driving strength of each OLED, controllers may compensate individual OLEDs for shifts in brightness and/or color based on the photodetector measurements of each OLED&#39;s aging. Compensations to driving strength may cause an OLED to emit brighter light and/or light of a different wavelength than before the compensation. This adjusted OLED may now emit light at a desired brightness and/or color. This may prolong the useful life of a display and maintain a desirable display appearance for longer than would otherwise be possible. 
     In other embodiments, multiple photodetectors may be disposed in an OLED display to sense the proximity of nearby objects, including a user&#39;s finger or face. Photodetectors may be disposed with OLEDs or zones of OLEDs across the display, as mentioned above, or in a peripheral area of the display to control when the OLED display is to be turned off. In an embodiment, when the photodetectors sense the user&#39;s face near the display, the display may be turned off. 
    
    
     
       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 with an electronic display and its components, in accordance with aspects of the present disclosure; 
         FIG. 2  is a perspective view of an example of the electronic device of  FIG. 1  in the form of a computer, in accordance with aspects of the present disclosure; 
         FIG. 3  is a front view of an example of the electronic device of  FIG. 1  in the form of a handheld device, in accordance with aspects of the present disclosure; 
         FIG. 4  is a cross-sectional side view of a portion of an OLED having a sensor disposed over an OLED device, in accordance with aspects of the present disclosure; 
         FIG. 5  is a cross-sectional side view of a portion of an OLED having a sensor in the OLED layer, in accordance with aspects of the present disclosure; 
         FIG. 6  is a cross-sectional side view of a portion of an OLED having a sensor disposed beneath an OLED device, in accordance with aspects of the present disclosure; 
         FIG. 7  is a front view of an OLED array with a respective photodetector disposed with each OLED, in accordance with aspects of the present disclosure; 
         FIG. 8  is a flowchart depicting a method for operating an OLED display to compensate for aging OLEDs, in accordance with aspects of the present disclosure; 
         FIG. 9  is a front view of zones across the display of a handheld device, in accordance with aspects of the present disclosure; 
         FIG. 10  is a front view of an OLED array arranged in zones with a photodetector disposed in each zone, in accordance with aspects of the present disclosure; 
         FIG. 11  is a flowchart depicting a method for operating an OLED display to compensate for ambient light, in accordance with aspects of the present disclosure; 
         FIG. 12  is a front view of photodetectors disposed on the periphery of the display of a handheld device, in accordance with aspects of the present disclosure; and 
         FIG. 13  is a flowchart depicting a method for operating an OLED display to detect objects near the display and alter the display in response, in accordance with aspects of the present disclosure. 
     
    
    
     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 is directed to systems, displays, and techniques integrating photodetectors with an electronic display to improve the appearance and/or functionality of the display. OLED displays use an array of OLEDs to show an image across the display. Each OLED emits light of a certain color and brightness based on its driving conditions and internal components. Ambient light may affect the perception and appearance of the color and/or brightness of the light emitted by the display. Photodetectors disposed within an OLED display may detect ambient light on different parts of the display so that OLED controllers may make compensations to the driving conditions of part or all of the display. Sufficient compensation results in a display with a uniform appearance regardless of differences in ambient light across the display. 
     Also, the color and brightness of an OLED are not constant over time under the same driving conditions. As an OLED ages, the color and/or brightness of its emitted light changes. Photodetectors disposed within an OLED display may detect these changes so that OLED controllers may make compensations to the driving conditions to counter the effects of aging. In some embodiments, photodetectors are disposed in the display with each OLED such that each OLED may be compensated according to its unique aging characteristics. In other embodiments, photodetectors may be disposed in the display with groups of OLEDs. For example, the driving strengths may be adjusted by manufacturing settings, user input, and/or transmitted information from sensors such as photodetectors. In some embodiments, calibration curves may be employed to adjust the driving strengths of OLEDs or zones of OLEDs to compensate for ambient light and/or aging effects. 
     The photodetectors also may be used to detect objects near the display. A photodetector may transmit information corresponding to a detected object to a controller. This transmitted information may be used to control the activation setting of the whole display or portions thereof. Furthermore, the transmitted information may be used to provide additional functionality to a touch screen interface. 
     A variety of electronic devices may incorporate the OLED displays having photodetectors disposed as mentioned above. One example appears in a block diagram of  FIG. 1 , which describes an electronic device  10  that may include, among other things, one or more processors  22 , memory  28 , nonvolatile storage  24 , a display  14 , input structures  16 , an input/output (I/O) controller  20 , I/O ports  18 , and/or a network device  26 . The various functional blocks shown in  FIG. 1  may include hardware, executable instructions, or a combination of both. In the present disclosure, the processor(s)  22  and/or other data processing circuitry may be generally referred to as “data processing circuitry.” This 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 . 
     As shown in  FIG. 1 , the processor(s)  22  and/or other data processing circuitry may be operably coupled with the memory  28  and the nonvolatile storage  24 . In this way, the processor(s)  22  may execute instructions to carry out various functions of the electronic device  10 . Among other things, these functions may include generating image data to be displayed on the display  14 . The programs or instructions executed by the processor(s)  22  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  28  and/or the nonvolatile storage  24 . The memory  28  and the nonvolatile storage  24  may represent, for example, random-access memory, read-only memory, rewritable flash memory, hard drives, and optical discs. 
     The depicted electronic device  10  includes a display  14 , such as an OLED display. In accordance with certain embodiments, the display  14  may include or be provided in conjunction with touch sensitive elements. Such a touch-sensitive display may be referred to as a “touch screen” and may also be known as or called a touch-sensitive display system. For example, the display  14  may be a MultiTouch™ touch screen device that can detect multiple touches at once. 
       FIG. 1  is merely one example of a particular implementation and is intended to illustrate generally the types of components that may be present in an electronic device  10 . These components may be found in various examples of the electronic device  10 . By way of example, the electronic device  10  of  FIG. 1  may be embodied as a computer as depicted in  FIG. 2 , a handheld device as depicted in  FIG. 3 , a tablet computer (not shown), or similar devices. Such electronic devices as depicted in  FIG. 2  may include a model of a MacBook®, a MacBook® Pro, MacBook Air®, iMac®, Mac® mini, or Mac Pro® available from Apple Inc. of Cupertino, Calif. 
     As illustrated in  FIG. 2 , electronic device  10  includes housing  12  that supports and protects interior components, such as processors, circuitry, and controllers, among others, that may be used to generate images on display  14 . Housing  12  also allows access to user input structures  16 , such as a touch screen, keypad, track pad, and buttons that may be used to interact with electronic device  10 . For example, user input structures  16  may be manipulated by a user to operate a graphical user interface (GUI) and/or applications running on electronic device  10 . In some embodiments, input structures  16  may be manipulated by a user to control properties of display  14 , such as the brightness or color. The electronic device  10  also may include various I/O ports  18  that allow connection of device  10  to external devices, such as a power source, printer, network, or other electronic device. 
     The electronic device  10  may also take the form of a handheld device  30 , as generally illustrated in  FIG. 3 . The handheld device  30  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  may be a model of an iPod® or iPhone® available from Apple Inc. of Cupertino, Calif. In other embodiments, the handheld device  30  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. 
     The handheld device  30  may include an enclosure  36  to protect interior components from physical damage and to shield them from electromagnetic interference. The enclosure  36  may surround the display  14 , which may display indicator icons  38 . The indicator icons  38  may indicate, among other things, a cellular signal strength, Bluetooth connection, and/or battery life. The I/O interfaces  18  may open through the enclosure  36  and may include, for example, a proprietary I/O port from Apple Inc. to connect to external devices. User input structures  16  in combination with the display  14 , may allow a user to control the handheld device  30 . A microphone  32  may obtain a user&#39;s voice for various voice-related features, and a speaker  34  may enable audio playback and/or certain phone capabilities. 
     OLED displays may be incorporated in the electronic device  10 , such as the computer or handheld device  30  as described above. Portions of different embodiments of photo-sensing OLED displays illustrated in  FIGS. 4-6  may generally be referred to as displays  14 A,  14 B, and  14 C respectively. It may be appreciated that the OLED layer  44  may have multiple components, including an anode and a cathode with one or more organic layers disposed between the anode and cathode. Upon application of an appropriate voltage to the OLED layer  44 , positive and negative charges combine in the organic layer(s) to emit light. The characteristics of this emitted light depend at least in part on the applied voltage and properties of the organic layer(s). 
     As illustrated in  FIG. 4 , an embodiment of an OLED display  14  may include multiple layers. The OLED layer  44  may be disposed over a substrate  46  and a top layer  40  may be disposed over the OLED layer  44 . The substrate  46  may include glass, plastic, other suitable materials, or combinations thereof, and may be either a rigid or flexible material. Further, in different embodiments the substrate  46  may be opaque, reflective, translucent, or transparent. The top layer  40  may form an environmental barrier to lessen the exposure of the OLED layer  44  to environmental elements such as air, oxygen, water, oils, radiation, and other elements with negative effects on the OLED layer  44 . In some embodiments, the top layer  40  may also protect the OLED layer  44  from direct environmental contact and shock. The top layer  40  may include glass, plastic, other suitable materials, or combinations thereof, and may be either a rigid or flexible material. 
     OLED displays may be categorized as bottom or top emission. In bottom emission OLED displays, the OLEDs emit light toward and through the substrate  46 . Bottom emission may utilize a transparent or semi-transparent substrate  46  and bottom electrode so that emitted light may pass through both layers. Top emission OLED displays include OLEDs that emit light opposite the substrate  46 . The substrate  46  of a top emission OLED display may be opaque, reflective, translucent, or transparent. 
     The OLED display  14  may also include a sensor layer  42 . The sensor layer  42  may include sensors such as photodetectors, photo diodes, photo resistors, photocells, and combinations thereof. In various embodiments the sensors may be disposed in the substrate such that they receive light from the direction of the substrate or the direction opposite the substrate, and combinations thereof. In some embodiments, a photo-sensing OLED display  14 A may include a sensor layer  42  disposed between the OLED layer  44  and the top layer  40 . The sensor layer  42  may be substantially transparent in the OLED display  14 A, such that light emitted by the OLED layer  44  may transmit through the sensor layer  42  and out of the OLED display  14 A. In another embodiment as illustrated in  FIG. 5 , the sensors and OLEDs may be on the same layer  43  between the substrate  46  and the top layer  40 . In such an embodiment, the photodetectors may be fabricated with the OLEDs during the thin film transistor (TFT) fabrication process or another fabrication process. In yet another embodiment as illustrated in  FIG. 6 , the sensor layer  42  may be disposed directly over the substrate  46  and beneath both the OLED layer  44  and top layer  40 . In another embodiment, sensors may be disposed in multiple layers. 
     The sensors disposed within layers  42  or  43  of OLED displays  14 A,  14 B, and  14 C may be configured to detect aging characteristics or OLEDs, ambient light, nearby objects, or any combination thereof. Sensors that receive the light emitted from OLEDs may be configured to detect aging characteristics. For example, for an OLED display  14 A as shown in  FIG. 5 , sensors disposed above the OLED layer  44  and directed towards top emission OLEDs may be configured to detect aging characteristics of the OLEDs. As another example, sensors directed upward and disposed below the OLED layer  44  of bottom emission OLEDs in accordance with  FIG. 6  may also be configured to detect aging characteristics. Sensors that receive ambient light may be configured to detect ambient light properties and nearby objects. For example, sensors directed toward the top layer  40  and disposed above the OLED layer  44  of top emission OLEDs may be configured to detect ambient light and/or nearby objects. 
     Additional details of the display  14  may be better understood through reference to  FIG. 7 , which is a schematic of an OLED array. A display  14  may have an array of OLEDs  66 , photodetectors  55 , a power driver  64   a , an image driver  64   b , a controller  62 , and possibly other components. The OLEDs  66  are driven by the power driver  64   a  and the image driver  64   b  (collectively drivers  64 ). In some embodiments, the drivers  64  may include multiple channels for independently driving multiple OLEDs  66  with one driver  64 . 
     The power driver  64   a  may be connected to the OLEDs  66  by way of scan lines S 0 , S 1 , . . . S m-1 , and S m  and driving lines D 0 , D 1 , . . . D m-1 , and D m . OLEDs  66  receive on/off instructions through the scan lines S 0 , S 1 , . . . S m-1 , and S m  and generate driving currents corresponding to data voltages transmitted from the driving lines D 0 , D 1 , . . . D m-1 , and D m . The driving currents are applied to each OLED  66  to emit light according to instructions from the image driver  64   b  through driving lines M 0 , M 1 , . . . M n-1 , and M n . Both the power driver  64   a  and the image driver  64   b  transmit voltage signals through respective driving lines to operate each OLED  66  at a state determined by the OLED controller  62 . Each driver  64  may supply voltage signals at a suitable duty cycle and/or amplitude sufficient to operate each OLED  66 . 
     Drivers  64  may include one or more integrated circuits that may be mounted on a printed circuit board and controlled by OLED controller  62 . Drivers  64  may include a voltage source that provides a voltage to OLEDs  66  for example, between the anode and cathode ends of each OLED layer. This voltage causes current to flow through the OLEDs  66  to emit light. Drivers  64  also may include voltage regulators. In some embodiments, the voltage regulators of the drivers  64  may be switching regulators, such as pulse width modulation (PWM) or amplitude modulation (AM) regulators. Drivers  64  using PWM adjust the driving strength by varying the duty cycle. For example, the OLED controller  62  may increase the frequency of a voltage signal to increase the driving strength for an OLED  66 . Drivers  64  using AM adjust the amplitude of the voltage signal to adjust the driving strength. 
     Each OLED  66  may emit light at an original brightness and original color when driven with an original drive strength. When the drive strength is adjusted, like by PWM or AM, the light emitted from an OLED  66  will vary from the original brightness and original color. For example, the duty cycles for individual OLEDs  66  may be increased and/or decreased to produce a color or brightness that substantially matches a target color or brightness for each OLED  66 . Furthermore, over time and through use of an OLED  66 , the color and brightness of emitted light will also vary even when driven with the original drive strength. In some embodiments, a controller  62  may adjust the drive strength of an OLED  66  throughout its useful life such that the color and/or brightness of its emitted light remains substantially the same, at least the same relative to other OLEDs  66  of the display  14 . 
     OLED controller  62  may adjust the driving strength by changing the drive instructions given to the drivers  64 . Specifically, OLED controller  62  may send control signals to drivers  64  to vary the voltage and/or the duty cycle applied to certain OLEDs  66 . For example, OLED controller  62  may vary the voltage applied by drivers  64  to an OLED  66  to control the brightness and/or the chromaticity of that OLED  66 . By increasing the voltage applied to an OLED  66 , the brightness of that OLED  66  increases. In contrast, decreasing the voltage applied to an OLED  66  decreases its brightness. In other embodiments, the ratio of the voltages applied to a group of OLEDs  66  may be adjusted to substantially match the brightness of other OLEDs  66  while maintaining a relatively constant color. 
     OLEDs  66  may be arranged in groups within the display to form pixels. Pixels may include groups of OLEDs  66  (e.g., three or four) emitting different colors, particularly complementary colors such as red, cyan, green, magenta, blue, yellow, white, and combinations thereof. These light colors from each OLED  66  are mixed according to instructions from the OLED controller  62  to create specific colors, including white, for each pixel. Together, the specific colors for each pixel of the display  14  form an image on the display  14 . The driving strength of some or all of the OLEDs  66  may be adjusted to achieve a uniform appearance for the display  14 . An ideal uniform display  14  may be such that if each pixel was instructed to emit the same color and brightness, a user would not perceive color or brightness variations across the display  14 . Rather, the entire display would have substantially the same color and brightness as perceived by the user. 
     The age of each OLED  66  and the ambient environment may alter the appearance of a display or portions of it unless these effects are compensated. OLEDs  66  of different colors typically do not have the same aging profiles. Some colored OLEDs, like red OLEDs, may produce substantially the same colored light at substantially the same brightness for many hours, while other colored OLEDs, particularly blue OLEDs, may exhibit substantial changes in color and brightness over the same period. Generalized brightness and chromaticity profiles may be stored in memory  28  to use for dynamically compensating OLEDs  66 . To compensate for such changes, different colored OLEDs  66  in the same pixel may be driven differently over time to emit light at the target brightness and/or target color. In addition, pixels may contain multiple OLEDs  66  of the same color so that some may be deactivated after a useful lifetime while others are activated. 
     In some embodiments, photodetectors  55  adjacent to OLEDs  66  provide the controller  62  with information related to the aging characteristics of OLEDs  66 . Photodetectors  55  may be coupled to the OLED controller  62  by way of photodetector lines P 0 , P 1 , . . . P k . In some embodiments as shown in  FIG. 7 , each photodetector  55  may be disposed with an OLED  66  in a 1:1 ratio. Each photodetector  55  measures the light emitted by its respective OLED  66  and transmits this measurement to the OLED controller  62 . Photodetectors  55  may measure the chromaticity (color) and brightness of emitted light. The OLED controller  62  may determine compensation adjustments to each OLED  66  based on a comparison between the measured and target values for color and/or brightness of each OLED  66 . 
     Complementary colors of light may be combined to produce substantially white light. However, different light sources may not produce the same shade of white. A white point of a light source is a set of chromaticity values used to compare light sources. The white point of a pixel is associated with its color and its component OLEDs. With respect to pixels of combined light sources, the required driving strength for each component color to maintain a white point may change due to numerous factors, including aging. 
     In some embodiments, to compensate for brightness and/or color shifts due to aging of OLEDs, OLED controller  62  may increase the driving strength of aged OLEDs  66 , decrease the driving strength of less aged OLEDs  66 , or increase the driving strength of some aged OLEDs  66  and decrease the driving strength of other less aged OLEDs  66 . Based on measurements from photodetectors  55 , OLED controller  62  may determine the direction of the white point shift of a pixel and increase the driving strength of one or more OLEDs  66  within or near the pixel with a color complementary to the white point shift. For example, if a photodetector  55  has detected that the white point of pixel has shifted towards a blue tint, OLED controller  62  may increase the driving strength of yellow tinted OLEDs  66  in or near that pixel. OLED controller  62  also may decrease the driving strength of one or more OLEDs  66  with a tint similar to the direction of the detected white point shift in this pixel. For example, if the white point has shifted towards a blue tint in a particular pixel, the OLED controller  62  may decrease the driving strength of blue tinted OLEDs  66  in that pixel. 
     OLED controller  62  may govern operation of a driver  64  using information stored in memory  28 . For example, memory  28  may store values defining the target brightness and/or color of each OLED  66 , as well as calibration curves, tables, algorithms, or the like. The memory  28  may also store values defining driving strength adjustments that may be made to compensate for a shift in the emitted brightness or color. In some embodiments, the OLED controller  62  may dynamically adjust the driving strengths throughout operation of the display  14  to maintain a light output that matches the target brightness or color. For example, OLED controller  62  may receive transmitted information from photodetectors  55  describing color and/or brightness of the emitted light. Using the transmitted information from photodetectors  55 , OLED controller  62  may adjust the driving strengths to maintain a light output from each OLED  66  that matches the target brightness and/or color for that OLED  66 . In an embodiment, OLEDs  66  may not be adjusted to compensate for differences between targeted and measured color and brightness if the adjustment would not be perceivable. An adjustment may not be perceivable if the difference between emitted and targeted light is slight. 
     In other embodiments, OLED controller  62  may receive signals from other sources instead of, or in addition to, photodetectors  55 . For example, OLED controller  62  may receive user transmitted information through input structure  16  ( FIG. 2 ) of electronic device  10 . Electronic device  10  may include hardware and/or software components allowing user adjustment of the brightness and/or color emitted by OLEDs  66  across the display  14 , or for particular portions of the display  14 . In some embodiments, display  14  may include a brightness control that allows a user to select the brightness within a set range. In other embodiments, display  14  may include a color temperature control that allows a user to select the color temperature (for example, from a set of fixed values) of the light emitted when display  14  receives an electrical signal corresponding to a white light. OLED controller  62  also may receive input from the device  10 . For example, the device  10  may include a clock that tracks total operating hours of OLEDs  66 . In some embodiments, OLED controller  62  may compare the operating hours to a calibration curve or table stored in memory  28  to determine a driving strength adjustment in conjunction with other adjustments made to OLEDs  66 . 
       FIG. 8  depicts a flowchart of a method  100  for employing photodetectors  55  to adjust the brightness and/or color of OLEDs  66  of a display  14  to compensate for aging. Aging may include shifts in the chromaticity or luminance of an OLED  66  over time and use. The OLED aging method  100  may begin by detecting (block  102 ) light emitted by the OLEDs  66 . In some embodiments, each photodetector  55  and each OLED  66  are disposed in the display in a 1:1 ratio. Other ratios are envisioned, including but not limited to 1:2, 1:3, 1:4, 1:6, 1:50, 1:100, 1:200 or ranges there between. An OLED controller  62  receives signals relating to the detected light from each photodetector  55 . The OLED controller  62  then compares (block  104 ) the properties of light emitted from each OLED  66  to the target color and brightness values for each OLED  66 . If a deviation exists, then the controller determines (node  106 ) whether compensation is needed for each OLED. Compensation may not be made if the adjustment would be imperceptible to end users or if the end user has disabled such adjustments, etc. In such circumstances where compensation is not made, the OLED controller  62  continues to monitor the signal from photodetectors  55  to determine when adjustments would be desirable. 
     If compensation for an OLED  66  should be made, the OLED controller  62  then determines (block  108 ) the compensation for each OLED  66  so that the emitted light substantially matches the targeted emitted light for each respective OLED  66 . The compensation may be determined by considering numerous factors, including OLED specific factors like the measured emitted light properties, present drive strength, previous drive strength adjustments, recorded operating hours, and/or information stored in memory  28  like calibration curves, algorithms, and charts. Based on these factors, the OLED controller  62  may then determine the changes in brightness and/or color needed to compensate each OLED  66  for the aging detected by the proximate photodetector  55 . Changes in brightness and/or color for each OLED  66  may improve the image quality of a display  14 . 
     For example, an OLED  66  may have aged more rapidly due to defective components, use, temperature, or other factors. This differentially aged OLED  66  may affect the appearance or viewability of the display because this OLED  66  has a different brightness and/or color from other nearby OLEDs  66  that aged normally. The OLED controller  62  may determine a driving strength adjustment to the differentially aged OLED  66  to make the emitted light substantially match other OLEDs  66  or a color and/or brightness target. Alternatively, the OLED controller  62  may determine a driving strength adjustment to the other less aged OLEDS  66  or surrounding OLEDs  66  to make the differentially aged OLED  66  less noticeable than before. As another alternative, the OLED controller  62  may determine driving strength adjustments to the differentially aged OLED  66  and the normally aged OLEDs  66  to improve the overall viewability of the display. The OLED controller  62  may employ AM, PWM, or other suitable techniques to vary the driving strength. 
     As discussed above, aging compensation adjustments to the driving strength of OLEDs  66  may be based on different factors. Adjustments may be made by the OLED controller  62  based on operating time and comparison with compensation information  70  stored in memory  28 , the signal from photodetectors  55 , and combinations thereof. For example, the OLED controller  62  may drive the OLEDs  66  in each zone according to calibration curves and algorithms stored in memory  28  and make fine tuning adjustments based on the signal from each photodetector  55 . Once the new driving strengths have been determined, OLED controller  62  may transmit (block  110 ) the adjustment instructions to the drivers  64 . 
     In some embodiments, each photodetector  55  may be disposed in the display  14  with more than one OLED  66 . In one embodiment illustrated in  FIG. 9 , photodetectors  55  are disposed in zones  60  of the display  14 . A photodetector  55  may be disposed in the display  14  in each zone  60  to detect light incident to each zone  60 . For example, light received by each zone  60  across the display  14  may not be uniform, affecting the appearance of the display. As described above, photodetectors  55  may detect light properties including the chromaticity and brightness. The photodetectors  55  may transmit information in the form of an electrical signal in response to the detected light to the OLED controller  62 . 
     In an embodiment, the display  14  includes an array of zones  60 . Each zone  60  includes at least one photodetector  55  and at two or more OLEDs  66  proximate to the photodetector  55 . In some embodiments, the photodetectors  55  may be able to detect red, green, blue, and/or white light and the intensities of such light. Photodetectors  55  that detect a certain color of light may be used to adjust the driving strength of proximate OLEDs  66  that emit that color of light. Furthermore, in some embodiments, zones  60  may overlap, such that some OLEDs  66  may lie in more than one zone. For example, each zone  60  may include multiple OLEDs  66  of only one OLED color (e.g., red zones, blue zones, and green zones). In one embodiment, one portion of the display  14  may include multiple overlapping zones where each zone  60  has a photodetector  55  capable of recognizing a particular color. For example, a first array of zones  60  may include a first OLED color (e.g., red) and a first photodetector  55  configured to detect the first OLED color, a second array of zones  60  overlapping the first array may include a second OLED color (e.g., green) and a second photodetector  55  configured to detect the second OLED color, and a third array of zones  60  overlapping both the first and second arrays may include a third OLED color (e.g., blue) and a third photodetector  55  configured to detect the third OLED color. This may reduce the number of photodetectors  55  utilized while providing information on zones  60  of OLEDs  66  of a particular color for fine-tuning adjustments to the display  14 . 
     The zones  60  may be arranged in a grid or in a matrix over the plane of the display  14  as shown in  FIG. 9 , but zone arrangements may not be limited to this configuration. In some embodiments, zones  60  may be arranged in strips, circles, or irregular shapes. Zones  60  may be of uniform shape and size across the display  14 , or have varied shapes and sizes. In some embodiments, certain areas of the display  14  will have more zones  60  and thus more photodetectors  55  than others areas. Zones  60  may be defined as having a certain number of OLEDs  66  or as the OLEDs  66  closest to each photodetector  55 . Furthermore, in some embodiments photodetectors  55  may be arranged only in corner zones  50  or edge zones  52 , or in other embodiments, only in interior zones  54 . 
       FIG. 10  illustrates a schematic of an OLED array with photodetectors disposed in zones  60  of OLEDs  66 . A display  14  may have an array of OLEDs  66 , photodetectors  55 , a power driver  64   a , an image driver  64   b , a controller  62 , and possibly other components. OLEDs  66  may be arranged in zones  60  such that each zone  60  includes a photodetector  55 . As described above, each zone  60  may contain one or more OLEDs  66 . In an embodiment as shown in  FIG. 10 , each zone  60  may include a pixel group containing one red OLED  66 R, one green OLED  66 G, one blue OLED  66 B and one white OLED  66 W. In other embodiments, each zone  60  may include a different number or color set of OLEDs  66 , and each zone  60  may not be limited to the OLEDs  66  of a single pixel. The OLEDs  66  and drivers  64  of the embodiment shown in  FIG. 10  may operate in substantially the same manner as described in  FIG. 7 . Similarly, the OLED controller  62  may adjust the driving strength of each OLED  66  or zone  60  of OLEDs  66 . 
     Photodetectors  55  are coupled to the OLED controller  62  by way of photodetector lines P 0 , P 1 , . . . P k . In some embodiments as shown in  FIG. 10 , each photodetector  55  may be disposed with a zone  60  of OLEDs  66 . Each photodetector  55  measures the light incident to or emitted by its respective zone  60 . In some embodiments, the measured light is light emitted by OLEDs  66  within the zone  60  and/or ambient light from external sources. Photodetectors  55  may measure the color and/or brightness of the received light. Each photodetector  55  may transmit signals relating these measurements within the zone  60  to the OLED controller  62 . 
     Each OLED  66  emits light in response to the driving signals supplied by the drivers  64 . The color and brightness of the emitted light may depend at least in part on the supplied driving signals and the internal components of the OLED  66 . Other light sources may affect the quality of the light emitted by each OLED  66 . For example, a bright light incident to a display  14  may greatly diminish the readability of text or graphics shown on the display  14  causing the display image to appear washed out. As another example, in dim light conditions, the OLED display  14  may need to emit light at a reduced brightness for a display image to be readable. Operating an OLED display  14  at a high brightness level at all times may not be desirable for many reasons including power consumption, eye strain, and aging effects on the OLEDs  66 . 
     Other situations may exist where an OLED display  14  is to be used in different colors of ambient light. The color of the ambient light may affect the perceived color of the display  14 . For example, a white display image may appear yellow when used in an environment with a yellow tinted ambient light. 
     Photodetectors  55  disposed throughout the display  14  in zones  60  may detect light incident to each zone  60  of the display  14 . Photodetectors  55  may transmit signals relating to the detected light to OLED controller  62  to determine how to counter the effects of the ambient light on the perceived brightness and color of the display  14 . The perceivability of a display may depend on the relationship between the properties of light incident on each zone  60  and the emitted brightness and color of each zone  60 . For any ambient light conditions, an optimal perceivability setting may exist such that the perceived brightness and color of a zone  60  driven at that setting substantially matches the target brightness and color for that zone  60 . The OLED controller  62  may determine the perceivability setting of a zone  60  based on the measured light values and target values for color and brightness of each zone. The OLED controller  62  may adjust the driving strengths of each zone  60  of OLEDs  66  based on the perceived brightness and color of each zone to match an optimal perceivability setting for the zone  60 . In an embodiment, driving each zone  60  at its optimal perceivability setting would result in a uniform display appearance. 
     To optimize the perceivability of each zone  60  for the effects of ambient light, OLED controller  62  may increase the driving strength of affected zones  60  of OLEDs  66 , decrease the driving strength of affected zones  60  of OLEDs  66 , or increase the driving strength of some affected zones  60  of OLEDs  66  and decrease the driving strength of other less affected zones  60  of OLEDs  66 . In some embodiments, the driving strength of each zone  60  may be adjusted according to the ambient light detected in each respective zone  60  to obtain an optimal perceivability setting for each zone  60  of the display  14 . For example, zones in a first portion of the display may be in a shadow, zones in a second portion of the display may be in bright light, and zones in a third portion of the display may be in a typical level of ambient light. Based on the detected levels of ambient light for each zone, the OLED controller  62  may decrease the driving strength of the zones in the first portion, increase the driving strength of the zones in the second portion, and not adjust the driving strength of the zones in the third portion. 
     OLED controller  62  may govern operation of the driver  64  using information stored in memory  28 . For example, memory  28  may store values defining the target brightness and/or color of each OLED  66 , as well as calibration curves, tables, algorithms, or the like. The memory  28  may also store values defining driving strength adjustments that may be made to compensate for differences in the perceived brightness or target color. In some embodiments, the OLED controller  62  may dynamically adjust the driving strengths of each zone  60  throughout operation of the display  14  to maintain a uniform display appearance through matching the perceived brightness and color of each zone to the target brightness and color for each zone. In some embodiments, OLEDs  66  may not be adjusted to compensate for differences between targeted and perceived color and brightness if the adjustment would not be perceivable. 
       FIG. 11  depicts a flowchart of a method  74  for employing photodetectors to adjust OLEDs  66  or zones  60  of a display to compensate for differences in targeted and perceived brightness and/or color of emitted light. The perception of emitted light from a display may depend on ambient light incident to the display  14 . The ambient light compensation method  76  may begin by detecting (block  76 ) light incident to the display  14 . In some embodiments, each photodetector  55  is disposed with an OLED  66  as described above. In other embodiments, each photodetector  55  is disposed in the display  14  with a group of OLEDs  66  in a zone  60 . A controller  62  receives signals related to the detected light across the display  14  from each photodetector  55 . The controller  62  then determines (block  78 ) the perceived properties of the light emitted from each zone  60  based on the detected light. The controller  62  then determines (node  80 ) whether compensation is desirable for each OLED  66  or zone  60 . This determination may be based on whether a difference between the perceived and targeted color and brightness values for each zone  60  exists. Compensation may not be desirable if the adjustment required would be imperceptible to end users or if the end user has disabled such adjustments, etc. In such circumstances where compensation is not desirable, the OLED controller  62  continues to monitor the signal from photodetectors  55  to determine when adjustments would be desirable for each zone  60 . 
     If compensation for an OLED  66  or zone  60  is desired, the OLED controller  62  then determines (block  82 ) the compensation for each OLED  66  so that the perceived emitted light substantially matches the targeted light for each OLED  66  or zone  60 . The compensation may be determined by considering numerous factors, including OLED specific factors like the measured emitted light properties, present drive strength, previous adjustments, recorded operating hours, and/or information stored in memory  28  like calibration curves, algorithms, and charts. Changes in brightness and/or color for each OLED  66  or zone  60  may improve the image quality of a display. The determined compensation may be in the form of adjustments to the driving instructions of each OLED  66  or zone  60 . 
     In some embodiments, the OLED controller  62  may determine a separate driving strength adjustment for each zone  60  based on the determined perceived light characteristics due to ambient light on each zone  60  to obtain an optimal perceivability setting for each zone. In other embodiments, the OLED controller  62  may determine a driving strength adjustment for each zone  60  based on the perceived light emitted from adjacent zones  60 . For example, the OLED controller  62  may increase the brightness of zones  60  in bright light to substantially match the perceived brightness of adjacent zones  60  in dim light. Alternatively, the OLED controller  62  may decrease the brightness of zones  60  in dim light to substantially match the perceived brightness of zones  60  in bright light. In other embodiments, the OLED controller  62  may determine driving strength adjustments for each zone  60  to obtain an optimal perceivability setting for the entire display  14 . The OLED controller  62  may employ AM, PWM, or other suitable techniques to vary the driving strength. 
     As discussed above, compensation adjustments to the driving strength of OLEDs  66  in each zone  60  based on detected ambient light may be based on different factors. Adjustments may be made by the OLED controller  62  based on operating time and comparison with compensation information  70  stored in memory  28 , the signal from photodetectors  55 , and combinations thereof. For example, the OLED controller  62  may drive the OLEDs  66  in each zone according to calibration curves and algorithms stored in memory  28  and may make fine tuning adjustments based on a signal from each photodetector  55 . Once the new driving strengths have been determined, OLED controller  62  may transmit (block  86 ) the adjustment instructions to the drivers  64 . 
     In some embodiments, photodetectors  55  may be utilized as proximity sensors. Photodetectors  55  utilized as proximity sensors may include photodiodes and photocells. Proximity sensors may detect nearby objects through observing changes in an ambient electromagnetic field or signal (e.g., infrared or visible light). Alternatively, proximity sensors may detect changes in an emitted electromagnetic field or signal. 
     Photodetectors  55  disposed in the display  14  to be utilized as proximity sensors may be disposed with each OLED  66  as shown in  FIG. 7 , disposed with zones  60  of OLEDs  66  as shown in  FIG. 10 , or disposed on the periphery of the display  14  as shown in  FIG. 12 . As described above, each photodetector  55  is coupled to the OLED controller  62 . When a photodetector  55  senses a nearby object, the photodetector  55  may transmit information in the form of an electrical signal to the OLED controller  62 . 
     Photodetectors  55  disposed in the display  14  and utilized as proximity sensors may provide a number of functionalities to an electronic device  10 . In some embodiments, photodetectors  55  may be used to turn a display  14  or portion of a display  14  on or off in a variety of situations, including when a laptop display is closed, a cellular phone is placed by an ear, a handheld device is placed in a pocket, or a portion of a display is covered. For example, if a portion of the display  14  is covered and fully obscured from view, the OLED controller  62  may determine that the OLEDs  66  in the covered zones should be turned off and only the OLEDs  66  in unobscured zones of the display should remain on. The unobscured zones of the display may show a shrunken version of the original display image or a modified image suitable for the smaller unobscured area. 
     In another embodiment, proximity sensors incorporated in a display may add touch screen functionality. For example, multiple photodetectors  55  may be utilized to predict the location at which an approaching object (e.g., a finger) may touch the display. In an embodiment, multiple photodetectors  55  may be used to discern approaching objects such that an entire cell phone display  14  is turned off when placed next to a user&#39;s ear, but the display  14  remains turned on when touched by a user&#39;s finger. 
       FIG. 13  depicts a flowchart of a method  88  for employing photodetectors as proximity sensors and making appropriate alterations to the display based on sensed nearby objects. The method  88  may begin by detecting (block  90 ) objects near each zone. Each photodetector  55  to be utilized as proximity sensors may be disposed with each OLED  66 , zones  60  of OLEDs  66 , or larger portions of the display  14 . Each photodetector  55  is also coupled to an OLED controller  62 . Photodetectors  55  may transmit information corresponding to detected nearby objects to the OLED controller  62 . The transmitted information may be in the form of electrical signals representing changes in the amount of light received by a photodetector  55  or distance from the photodetector  55  to the object that OLED controller  62 . 
     Based on the signals transmitted by each photodetector  55 , the OLED controller  62  determines (node  92 ) whether all or portions of the display  14  need to be adjusted. This determination may be based on many factors, including the distance to the detected object and to the size, direction, and identity of the detected object. For example, a finger approaching the display  14  may require an adjustment to at least a portion of the display due to the finger&#39;s distance and identity; however, a hand passing over the display  14  may not require an adjustment due to the hand&#39;s distance and direction. As another example, the controller may determine the difference in transmitted photodetector signals between operating the display  14  in a dark room and placing the display  14  into a pocket so that the display remains on in a dark room but turns off in a pocket. In such circumstances where adjustment is not needed, the OLED controller  62  continues to monitor the signal from photodetectors  55  to determine when adjustments would be needed to parts of the display  14 . 
     If adjustment for all or part of the display  14  is needed, the OLED controller  62  then determines (block  94 ) the adjustment needed for each OLED  66  of the display  14 . The adjustment needed may be determined by considering numerous factors, including current use of the electronic device  10 , ambient light, what portions of the display detect the object(s), and information stored in memory  28 . The determined compensation may be in the form of adjustments to the driving signal or scan signal of each OLED  66  or zone  60 . Once the new driving strengths have been determined, OLED controller  62  may transmit (block  98 ) the adjustment instructions to the drivers  64 . 
     While many of the embodiments illustrated and described mention photodetectors disposed with OLEDs or zones of OLEDs, it should be further understood that photodetectors disposed in the display with any number of OLEDs may be utilized in any method herein described. Furthermore, it is intended that the photodetectors may be used for aging compensation, ambient light compensation, proximity sensing, and combinations thereof as illustrated in  FIGS. 8 ,  11 , and  13 . 
     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: 20120201
Publication Date: 20150623
Grant Date: 20150623
Priority Date: 20120201
Inventors: LYNCH STEPHEN BRIAN
DRZAIC PAUL STEPHEN
RAPPOPORT BENJAMIN MARK
ROTHKOPF FLETCHER R.
TERNUS JOHN PATRICK
MYERS SCOTT ANDREW
Assignee: APPLE INC
CPC Classifications: [{"code": "G09G2320/0242", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/3208", "inventive": true, "first": true, "tree": "[]"}, {"code": "G09G2360/147", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/029", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/0412", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2360/144", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/0421", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2320/0233", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/045", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2360/147", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2360/144", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/045", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/029", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0242", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0233", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/3208", "inventive": true, "first": true, "tree": "[]"}, {"code": "G09G3/3208", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F3/0421", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0412", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2320/0626", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0666", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/043", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2360/147", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/029", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0233", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/045", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2360/144", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0242", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/0421", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0412", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 48869778