PATENT DOCUMENT

Publication Number: US-9177503-B2
Application Number: US-201213484887-A
Country: US
Kind Code: B2

Title: Display having integrated thermal sensors

Abstract:
Thermal sensors are disposed with OLEDs across a display of an electronic device to measure temperatures across the display surface. Thermal sensors may be used to create a temperature map across the display surface due to both the ambient environment and the internal environment of the electronic device. The thermal sensors may be disposed in the OLED layer, on a separate layer, or both. Thermal sensors may be disposed in a substantially 1:1 ratio with OLEDs or with zones of OLEDs. Both the temperature history and usage history for OLEDs may be recorded and processed to determine the age of each OLED. Controllers may adjust the driving strength of OLEDs or adjust the operation of components within the electronic device to compensate for aging or temperature based on the temperature map and age determination. Controllers may move static images from one part of the display to another less-aged part.

Claims:
What is claimed is: 
     
       1. A display, comprising:
 a plurality of organic light emitting diodes (OLEDs) disposed across the display, 
 wherein each OLED of the plurality of OLED emits light in response to control signals; 
 a plurality of thermal sensors disposed across the display, the plurality of thermal sensors being configured to measure a plurality of temperatures across the display and generate signals relating to the measured plurality of temperatures; and 
 a controller configured to move a location of an image on the display from a first location to a second location based at least in part on the signals relating to the measured plurality of temperatures, and a first average temperature of the first location is greater than a second average temperature of the second location due substantially to heat from electronic components proximate the display. 
 
     
     
       2. The display of  claim 1 , wherein the plurality of OLEDs and the plurality of thermal sensors are disposed on a common layer of the display. 
     
     
       3. The display of  claim 1 , wherein the plurality of OLEDs is disposed on a layer of the display and the plurality of thermal sensors is disposed on a different layer of the display. 
     
     
       4. The display of  claim 1 , wherein each OLED of the plurality of OLEDs is disposed across the display with a respective thermal sensor of the plurality of thermal sensors 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 measured temperature of the plurality of measured temperatures from the respective thermal sensor. 
     
     
       5. The display of  claim 1 , wherein the controller is configured to determine the control signals for the plurality of OLEDs based at least in part on an age of the OLEDs. 
     
     
       6. The display of  claim 1 , wherein the controller is configured to adjust a brightness or a color of the plurality of OLEDs in a portion of the display based at least in part on a difference between the measured temperature of the portion of the display and the measured temperature of a remainder of the display. 
     
     
       7. The display of  claim 1 , wherein the controller is configured to determine the control signals for the plurality of OLEDs based at least in part on a running average operating temperature of the OLEDs, a maximum operating temperature, a minimum operating temperature, or any combination thereof. 
     
     
       8. The display of  claim 1 , wherein the controller is configured to store the plurality of measured temperatures in a memory and determine the control signals for the plurality of OLEDs based at least in part on the measured temperatures stored in memory. 
     
     
       9. The display of  claim 1 , wherein the controller is configured to determine the control signals for each OLED to compensate for shifts in a color, or a brightness, or a combination thereof. 
     
     
       10. An electronic device, comprising:
 a housing; 
 data processing circuitry disposed within the housing, wherein the data processing circuitry comprises a central processing unit, a graphical processing unit, a radio frequency transmitter, or any combination thereof; 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; and 
 a plurality of thermal sensors disposed across the display, configured to measure a plurality of temperatures across the display and generate signals relating to the measured plurality of temperatures; and 
 
 
 a controller configured to receive image data from the data processing circuitry and to determine control signals for the plurality of OLEDs based at least in part on the signals relating to the measured plurality of temperatures, and the controller is configured to create a temperature map based at least in part on the plurality of measured temperatures, to determine the control signals for the plurality of OLEDs based at least in part on the temperature map, and the controller is configured to move an image from a first portion of the display to a second portion of the display based at least in part on the temperature map, wherein a first average temperature of the first portion of the display is greater than a second average temperature of the second portion of the display, and the first average temperature of the first portion is greater than the second average temperature due primarily to heat generated by the data processing circuitry. 
 
     
     
       11. The electronic device of  claim 10 , wherein the display is disposed over the central processing unit, the graphical processing unit, or the radio frequency transmitter, or any combination thereof, and the controller is configured to adjust the data processing circuitry to reduce heat generated by the data processing circuitry disposed beneath the display. 
     
     
       12. The electronic device of  claim 10 , wherein the plurality of OLEDs and the plurality of thermal sensors are disposed on a common layer of the display screen. 
     
     
       13. The electronic device of  claim 10 , wherein each OLED of the plurality of OLEDs is disposed across the display with a respective thermal sensor of the plurality of thermal sensors 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 respective measured temperature of the plurality of measured temperatures from the respective thermal sensor. 
     
     
       14. The electronic device of  claim 10 , 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 thermal sensor of the plurality of thermal sensors, 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 measured temperature from the at least one thermal sensor of that zone. 
     
     
       15. The display of  claim 10 , wherein the controller is configured to adjust the data processing circuitry based at least in part on the signals relating to the measured plurality of temperatures. 
     
     
       16. The display of  claim 10 , wherein the controller is configured to store the plurality of measured temperatures in a memory and create the temperature map based at least in part on the stored plurality of temperatures. 
     
     
       17. The electronic device of  claim 16 , wherein the controller is configured to determine the control signals for the plurality of OLEDs based at least in part on a running average of measured temperatures stored in the memory. 
     
     
       18. The display of  claim 10 , wherein the controller is configured to determine a degree of aging for the OLEDs based at least on the temperature map and determine the control signals for the plurality of OLEDs based at least in part on the degree of aging for the OLEDs. 
     
     
       19. The display of  claim 15 , wherein adjustments to the data processing circuitry comprise changing an operating speed of the central processing unit, changing an operating speed of the graphical processing unit, or changing a signal power of the radio frequency transmitter, or any combination thereof. 
     
     
       20. The display of  claim 10 , wherein the controller is configured to adjust the control signals for the plurality of OLEDs to adjust a brightness or a color of the plurality of OLEDs in a portion of the display based at least in part on a difference between the measured temperature of the portion of the display and the measured temperature of a remainder of the display. 
     
     
       21. A method of operating an electronic device, comprising:
 driving a plurality of organic light emitting diodes (OLEDs) disposed across a display to emit light with control signals; 
 measuring temperature across the display by a plurality of thermal sensors disposed across the display; 
 determining effects of the measured temperature across the display on the light emitted by the plurality of OLEDs; 
 identifying a duration of operation of each OLED of the plurality of OLEDs above a threshold temperature; 
 moving a location of an image on the display from a first location to a second location based at least in part on the measured temperature across the display, wherein a first average temperature of the first location is greater than a second average temperature of the second location due substantially to heat from electronic components of the electronic device; and 
 adjusting the control signals based at least in part on the determined effects of the measured temperature and the identified durations of operation of the plurality of OLEDs above the threshold temperature, wherein the control signals are adjusted to affect the light emitted by the plurality of OLEDs. 
 
     
     
       22. The method of  claim 21 , comprising adjusting the drive signals for at least one component of a plurality of components of the electronic device beneath the display based at least in part on the measured temperature, wherein the plurality of components comprises a central processing unit, a graphical processing unit, or a radio frequency transmitter, or any combination thereof, and adjusting the drive signals for the at least one component of the plurality of components is configured to reduce heat generated by the at least one component. 
     
     
       23. The method of  claim 21 , comprising adjusting the control signals to affect the light emitted by the plurality of OLEDs to produce a uniform display appearance. 
     
     
       24. The method of  claim 21 , comprising adjusting the control signals to affect the light emitted by at least some OLEDs of the plurality of OLEDs in a portion of the display based at least in part on a difference between the measured temperature of the portion and the measured temperature of a remainder of the display. 
     
     
       25. The method of  claim 24 , wherein adjusting the control signals of at least some OLEDs of the plurality of OLEDs compensates a color, or a brightness, or a combination thereof of the light emitted by the at least some OLEDs. 
     
     
       26. The method of  claim 21 , comprising moving a location of an image on the display based at least in part on the measured temperature across the display to reduce a total of the adjustments to the control signals for the plurality of OLEDs.

Description:
BACKGROUND 
     The present disclosure relates generally to electronic displays and, more specifically, to displays with integrated thermal sensors. 
     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, 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. Furthermore, aging may be accelerated by heat. 
     While OLED displays do not require a backlight, a variety of other electrical components may be placed in various locations beneath a display. These components facilitate the operation and function of the electronic device. Some components of an electronic device that may be beneath an OLED display include processors, radio transmitters, batteries, speakers, cameras etc. Some of these components draw current and may warm during use. Some components, such as a processor or radio transmitter, may get particularly warm during use or extended use. As a result, portions of the display may also warm due to these warming components beneath the display. Moreover, because some components may warm more than other components, some portions of the display may warm more than other portions. 
     Heat may affect characteristics of emitted light from OLEDs. In addition to accelerating aging, the color and brightness of light emitted by OLEDs may be affected by the operating temperature. The brightness of some OLEDs, particularly red OLEDs, may decrease as operating temperatures increase. Over time as each OLED ages due to use and temperature, images shown on parts of the display may appear different from the intended image. Controllers may make changes to compensate for such shifts in brightness and color. However, color and brightness shifts may occur differently across a display due to unpredictable use of each OLED and the components beneath each OLED. 
     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. 
     Aging may occur in an unpredictable manner due to differential use of the display and components by end users. Knowing the operating temperature, temperature history, and/or usage history of the OLEDs could improve compensation. Accordingly, embodiments of the present disclosure relate to OLED displays and techniques to adjust OLED displays to maintain a desired appearance. Thermal sensors may be integrated in the OLED display and may be used to determine a present temperature, a temperature history, and/or a thermal profile of individual OLEDs or zones of OLEDs so that the control signals to the OLED or zones of OLEDs may be adjusted to compensate for temperature and/or thermal aging. Thermal sensors integrated in the display may also be used to determine thermal characteristics of components beneath the display to adjust the operation of the components. In an embodiment, each OLED is associated with a thermal sensor to measure the temperature and/or aging characteristics of that particular OLED. The integrated thermal sensors may enable controllers to maintain a substantially uniform display appearance throughout the life of the display regardless of use and temperature variations. 
     OLEDs at high operating temperatures may emit light different from OLEDs at low operating temperatures, which may result in a poor display quality for displays with non-uniform temperature gradients. Non-uniform temperatures may exist across a display due to the ambient environment, power consumed by components of the OLED display, or heat emitted by components beneath the OLED display (e.g., processor, radio transmitter). In some embodiments, integrated thermal sensors measure the temperature of the OLEDs across the display to create a temperature map. The temperature map may indicate OLEDs with present operating temperatures beyond known thresholds such that the emitted light does not match the target emitted light and/or the temperature map may relate to historical average temperatures of the OLEDs, where average higher temperatures may indicate which OLEDs are aging faster with respect to other OLEDs. In some embodiments, controllers may adjust the driving strength of the OLEDs to compensate for shifts in brightness and/or color based at least in part on the temperature map of the display. In other embodiments, controllers may move the image to be displayed from one portion of the display to another portion based at least in part on the temperature map of the display. In still other embodiments, the operation of some components beneath the OLED display may be adjusted or slowed based at least in part on the temperature map of the display. 
     As mentioned above, aged OLEDs may emit light different from less aged OLEDs, and operating temperature affects aging. As OLEDs age at different rates and are subject to prolonged increased operating temperatures, the overall quality of a display appearance may decrease. In some embodiments, the temperature map may contribute to an aging determination for each OLED. Temperature and usage histories may be recorded in memory and used to determine the aging of each OLED or portion of the display. 
     Controllers may determine compensations for each OLED such that the light emitted from each OLED substantially matches the light target for each OLED. In some embodiments, compensations may be based on comparing the aging determination with calibration curves, tables, algorithms, or the like stored in memory. Controllers may adjust the driving strength for each OLED to emit light with the target properties to compensate for the affects of operating temperature and/or aging. This adjustment may prolong the useful life of a display and maintain a desirable display appearance for longer than would otherwise be possible. 
    
    
     
       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 thermal 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 thermal 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 thermal sensor disposed beneath an OLED device, in accordance with aspects of the present disclosure; 
         FIG. 7  is a chart depicting the effects of aging on a white point of an OLED, in accordance with aspects of the present disclosure; 
         FIG. 8  is a chart depicting the effects of temperature on OLED chromaticity, in accordance with aspects of the present disclosure; 
         FIG. 9  is a schematic of an OLED array with a thermal sensor for each OLED, in accordance with aspects of the present disclosure; 
         FIG. 10  is a front view of the placement of components within an electronic device, in accordance with aspects of the present disclosure; 
         FIG. 11  is a graphical representation of a temperature map of a display over the components placed as shown in  FIG. 10 , in accordance with aspects of the present disclosure; 
         FIG. 12  is a front view of zones across the display of a handheld device, in accordance with aspects of the present disclosure; 
         FIG. 13  is a schematic of an OLED array arranged in zones with a thermal sensor disposed in each zone, in accordance with aspects of the present disclosure; 
         FIG. 14  is a flowchart depicting a method for operating an OLED display to adjust components or OLEDs based on a temperature map, in accordance with aspects of the present disclosure; and 
         FIG. 15  is a flowchart depicting a method for operating an OLED display to adjust each OLED based on the age of each OLED, 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 thermal sensors with an electronic display to control portions of the display and/or components beneath a display differentially based at least in part on temperature measurements from the thermal sensors. 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 structure. These systems, displays, and techniques may be used to improve the appearance of a display by compensating OLEDs for changes in brightness and/or color. 
     The color and brightness of an OLED is not constant over time under the same driving conditions. The properties of light emitted by an OLED may be dependent upon the operating temperature. Thermal sensors integrated within an OLED display may measure the operating temperature so that controllers may make compensations to the driving conditions to counter the temperature effects. In some embodiments, thermal sensors are disposed in the display with the OLEDs such that each OLED may be compensated according to its measured operating temperature. In other embodiments, thermal sensors may be disposed in the display with groups of OLEDs across the display. The temperature measurements from thermal sensors across the display may be used to generate a temperature map to indicate temperatures across the display. 
     The temperature map also may be utilized to determine the heat generated by components beneath a display. In some embodiments, a controller may adjust the operation of a component to change the temperature of particular zones. In a certain embodiment, the controller slows down the component. In another embodiment, the controller adjusts a signal strength. 
     Even if all OLEDs of a display are adequately compensated for operating temperature, the aging of OLEDs may also affect the properties of light emitted by the OLEDs. Furthermore, temperature affects aging. Temperatures recorded over time from a temperature map may create a temperature history (e.g. a running average temperature) for each OLED, and the temperature history may be stored in memory. A usage history stored in memory may include the total operation time for each OLED. The temperature and usage histories may be used to determine the degree of aging for each OLED. Controllers may then make compensations to the driving strengths of each OLED based on the determined degree of aging. In some embodiments, sufficient compensation results in a substantially uniform display appearance regardless of variations in operating temperature or aging across the display. 
     In some embodiments, the driving strengths may be adjusted by manufacturing settings, user input, and/or transmitted information from sensors such as thermal sensors. In some embodiments, calibration curves may be employed to adjust the driving strengths of OLEDs or portions of the display to compensate for operating temperature and/or aging effects. 
     A variety of electronic devices may incorporate the electronic displays with integrated thermal sensors 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  (e.g. central processing unit (CPU), graphical processing unit (GPU)), memory  28 , 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 . 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 . The memory  28  may represent, for example, random-access memory, read-only memory, rewritable flash memory, hard drives, and optical discs. 
     The depicted electronic device 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 the types of components that may be present in 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 represent a block diagram of a computer as depicted in  FIG. 2 , a handheld device as depicted in  FIG. 3 , 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 to display 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 certain 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. 
     The cross-sectional side views of portions of OLED displays shown in  FIGS. 4-6  may be incorporated in any electronic device  10 , including a computer or handheld device  30  as described above. Portions of different embodiments of OLED displays with integrated thermal sensors are illustrated in  FIGS. 4-6  and may generally be referred to as displays  14 A,  14 B, and  14 C. It may be appreciated that the OLED layer  44  typically has many components, such as an anode, cathode, and 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 light, including brightness and color, 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 A 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 require 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 A may also include a sensor layer  42 . The sensor layer  42  may include sensors such as thermal sensors, thermocouples, thermistors, resistance thermometers, or combinations thereof. In some embodiments, a thermal-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  of the display  14 B. In such an embodiment, the thermal sensors may be fabricated with the OLEDs during the thin film transistor (TFT) fabrication process or another 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  of the OLED display  14 C. In other embodiments, sensors may be disposed in multiple layers. 
     Some groups of OLEDs, called pixels, within the OLED layer  43  and  44  may emit complementary colors of light (e.g., red, green, blue, cyan, magenta, yellow) that may be combined to produce various colors of light, including 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 light source is associated with its color and its component lights. With respect to pixels of combined OLEDs, the required driving strength for each component color to maintain a white point may change due to numerous factors, including temperature and use. 
     As a further complication, OLEDs of different colors may not have the same usage profiles. For example, the brightness of blue OLEDs may decrease more quickly than the brightness of red OLEDs operated for the same length of time. Furthermore, the color of light emitted from an OLED may shift over time. By way of example,  FIG. 7  depicts chart  114  that illustrates how the chromaticity of a yellow OLED may shift over time as the OLED ages. Specifically, chart  114  illustrates the change in chromaticity for a light that includes a yellow phosphor OLED. Chromaticity may be defined by set of x and y chromaticity values corresponding to the x-axis and y-axis respectively of a color space chromaticity diagram. In the chart  114 , the y-axis  116  shows the chromaticity values, and x-axis  118  shows the operational life of the light in hours. The x chromaticity values are shown by curve  120 , and they chromaticity values are shown by curve  122 . As shown by curve  120 , the x values may generally shift from red to blue with use. As shown by curve  122 , the y values may generally shift from yellow to blue with use. Overall, the white point of this light may shift towards a bluish tint. 
     Furthermore, OLEDs of different colors may not have the same temperature profiles either. As an example, the brightness of red OLEDs may decrease at high temperatures more than blue OLEDs at the same temperatures. High temperatures may also accelerate aging shifts in brightness or color.  FIG. 8  depicts chart  124  that illustrates how the brightness of different colored OLEDs may change with temperature. The y-axis  126  indicates the relative flux of the OLEDs, and the x-axis indicates the temperature  128  in degrees Celsius. In general, the flux may be the relative percentage of the total amount of light from an OLED. Separate lines  130 ,  132 , and  134 , each correspond to different color OLEDs, normalized to 25 degrees Celsius. Specifically, line  130  represents the change in flux for a red OLED, line  132  represents the change in flux for a blue OLED, and line  134  represents the change in flux for a green OLED. The flux generally decreases as the temperature increases, and the rate of decrease in the flux varies between different color OLEDs. The differing rates of change may cause a shift in the white point. For example, the white point of a pixel may shift with increased temperature because the relative flux of the OLEDs within the pixel may change. 
     To address these concerns,  FIG. 9  illustrates a display  14  having an array of OLEDs  66 , thermal sensors  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 image driver  64   b  (collectively drivers  64 ). Each power driver  64   a  and image driver  64   b  may drive one or more OLEDs  66 . 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 controller  62  to emit light. Each driver may supply voltage signals at a 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 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, the color and brightness of emitted light from an OLED will also vary due to temperature and age 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, or 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, 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, 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 may be adjusted to substantially match the brightness of other OLEDs 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  may be mixed according to instructions from the 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 light of 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. 
     In some embodiments, thermal sensors  55  may be disposed in the display  14  with the OLEDs  66  to provide the controller  62  with the operating temperature of OLEDs  66 . Thermal sensors  55  are coupled to the OLED controller  62  by way of thermal sensor lines T 0 , T 1 , . . . T k . In some embodiments as shown in  FIG. 9 , each thermal sensor  55  may be disposed in the display  14  with an OLED  66  in a 1:1 ratio. Each thermal sensor  55  measures the operating temperature of the OLEDs  66  and transmits this measurement to the controller  62 . The controller  62  may store the measured operating temperature in memory  28 . In some embodiments, the controller  62  may store parameters of the temperature history such as the maximum operating temperature, minimum operating temperature, running average temperature of the thermal sensor  55  during operation, the duration of operation of OLEDs  66  above threshold temperatures, or combinations thereof. 
     The 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 and/or color. In some embodiments, the controller  62  may dynamically adjust driving strengths throughout operation of the display  14  to maintain a light output that matches the target brightness or color for each OLED  66 . The operating temperature, temperature history, and usage history of each OLED  66  may cause the emitted color or brightness of each OLED  66  to fail to match the target brightness or color unless these effects are compensated. 
     The controller  62  may determine compensation adjustments to each OLED  66  based on a comparison of the measured operating temperature and calibration curves, tables, algorithms, or the like stored in memory  28 . In some embodiments, the compensations may change the brightness and/or color of light emitted by each OLED  66  to match the brightness and/or color target for that OLED  66 . The controller  62  may also generate a temperature map from the measured operating temperatures to identify measured operating temperatures across the display. The temperature map may indicate various temperature parameters across the display including actual operating temperatures, relative temperatures, changing temperatures, temperature history (e.g., running average temperature) etc. The controller  62  may utilize the temperature map to adjust the driving strength of each OLED  66  to compensate for shifts in the color and/or brightness due to temperature affects. In some embodiments, adjustments may be made to the whole display. In other embodiments, adjustments may be made to only certain parts of the display that are more affected by temperature and/or age. For example, the adjustments made by controller  62  may change the location that an image is shown on a display  14 . The image location may be changed to an area of the display with different temperature map characteristics, such as moving an image to be shown by OLEDs  66  with a lower or more uniform temperature. 
     The thermal sensors  55  integrated in the display  14  may measure the operating temperature of OLEDs  66  due to both the ambient environment and environment within the electronic device  10 . In the embodiment shown in  FIG. 10 , components  57  within a handheld device  30  are shown beneath display  14 . Due to the display  14  covering much of the surface area of one side of the handheld device, many components  57  lie entirely or at least partially beneath a portion of the display  14 . Components  57  may include, but are not limited to, a radio frequency (RF) transmitter  50 , a battery  51 , CPU  52 , GPU  53 , and heat sinks  54 . A RF transmitter  50  may send and receive electromagnetic signals for many applications, including phone calls, internet browsing, Bluetooth connectivity, etc. A battery  51  powers the components of the handheld device  30 . A CPU  52  may perform a myriad of processing functions for the handheld device  30 . A GPU  53  may process graphics to be displayed on display  14 . Heat sinks  54  may be physically coupled to a number of components  57  to dissipate heat. 
     During user operation of the handheld device  30 , components  57  will be used in varying amounts. Current flows through components  57  may generate heat through resistance heating, warming components and portions of the display  14 . Some components  57 , such as heat sinks  54 , may be physically coupled rather than electrically coupled to other components  57 . Such physically coupled components  57  may not generate heat themselves, but may conduct heat from one warm component  57  to another cooler area of the handheld device  30 . Thermal sensors  55  integrated across the display  14  may measure the operating temperature of the OLEDs  66  of the above display  14 . As shown in  FIG. 11 , temperature measurements may be used to generate a temperature map  75  of the display  14 , which may contribute to the temperature history for each OLED  66  of the display  14 . In an embodiment, the temperature map  75  may be shown on the display  14 . 
     In an embodiment, current flows and heat generation may not be the same from one component  57  to another. Some components  57  may draw more current, thus generating more resistance heat, than others during certain user operations. For example, a user that primarily uses the handheld device  30  for phone calls or Internet downloads may utilize the RF transmitter  50  more than another user that primarily listens to music stored on the handheld device. As another example, a user may use applications that place heavy demands on the CPU  52  but not the GPU  53 , while another user may use applications (e.g., games) that are graphically intense  53  but do not utilize the CPU  52  as much. The actual end use of the handheld device may vary from one user to another, resulting in differential temperatures across the display  14  at any given time and historically. Accordingly, temperature maps  75  will vary according to use. 
     An example of a temperature map  75  that corresponds to heavy CPU  52  usage and relatively light RF transmitter  50  usage of a hypothetical electronic device  10  is shown in  FIG. 11 . As discussed above, the controller  62  may store measured temperatures from the thermal sensors  55  to generate the temperature map  75 . The temperature map  75  illustrated here indicates the recorded running average operating temperatures across the display  14 . The temperature map  75  may convey the running average temperatures for each OLED  66  or for groups of OLEDs  66  (e.g., one or more pixels). For example, the average temperatures of the display  14  from warmest to coolest shown here may be the CPU temperature profile  72 , followed by the GPU temperature profile  73 , battery profile  71 , and RF transmitter profile  70 . In an embodiment, each temperature profile  70 ,  71 ,  72 ,  73 , and  74  may closely correspond to the locations of components within the handheld device  30  (e.g.,  FIG. 10 ). Temperature profiles related to particular components  57  may not be uniform. For example, heat may be localized within a component  57 . In an embodiment, the heat sink profile  74  illustrates heat conducted away from the warmest components  57 . The heat sink portion  76  nearest to the CPU  52  may be warmer than the heat sink portions  77  and  78  further from the CPU  52 . 
     As discussed above, in an embodiment, the controller  62  ( FIG. 9 ) may utilize the temperature map  75  to determine the compensation for OLEDs  66  to counter color and/or brightness shifts due to the measured operating temperature. In another embodiment, the temperature map  75  may be utilized to estimate the temperature of each component  57  beneath the display. The controller  62  may adjust the operation of a component  57  based on its affect on the operating temperature of certain OLEDs  66 . For example, the temperature map  75  above the CPU  52  may indicate an increased operating temperature, affecting light emitted by the OLEDs  66  above the CPU. Based on the temperature map  75 , the controller  62  may slow the CPU  52  to lower the operating temperature for the OLEDs  66  above the CPU  52 . This may compensate for a shift in brightness and/or color of some OLEDs  66  by lowering the temperature without changing the driving strengths of those OLEDs  66 . In some embodiments, the controller  62  may adjust both the driving strengths of OLEDs  66  and the operation of components  57  based on the temperature map  75 . For example, the controller  62  may slow the CPU  52  and increase the driving strength for OLEDs  66  above the CPU to compensate for shifts in the brightness and/or color of those OLEDs  66   
     In some embodiments, the controller  62  may store a usage history in memory  28 . Whereas the temperature history may pertain to measured temperatures by the thermal sensor  55  disposed across the display  14 , the usage history may pertain to the measured use of OLEDs  66  disposed across the display  14 . For example, the controller  62  may store the operating hours and/or drive strengths applied to the OLEDs  66  as usage history. 
     The controller  62  may use the temperature history and usage history of OLEDs  66  to determine the aging of each OLED  66 . Because temperature may affect the rate of aging through use, the controller  62  may determine the amount of aging due to temperature. The controller  62  may also determine compensation adjustments to the driving strengths for each OLED  66  based on a comparison of the degree of aging with calibration curves, tables, algorithms, or the like stored in memory  28 . In some embodiments, the controller  62  may make driving strength adjustments to each OLED  66  based on its age alone to compensate for shifts in color and/or brightness. Without such adjustments, outlines of components  57  may become visible on the display  14  over time as certain OLEDs  66  age faster, negatively affecting the appearance of the display  14 . 
     In other embodiments, the controller  62  may make driving strength adjustments to the OLEDs  66  based on the age and present operating temperature of the OLEDs  66 . As discussed above, the controller  62  may adjust the driving strengths of OLEDs  66  to compensate for shifts in emitted color and/or brightness. In some embodiments, the controller  62  may make compensations to change the location that an image is shown on a display  14 . The image location may be changed to an area of the display with different temperature map aging characteristics, or both. For example, an image to be displayed over part of the RF transmitter  50  may be moved to be displayed over the battery  51  because the OLEDs  66  over the RF transmitter  50  are warmer on average and thus more aged than the OLEDs  66  over the battery  51 . In some embodiments, images may be moved across the display  14  to obtain an optimal appearance for an image or to minimize adjustments to OLEDs  66 . 
     Generally, the controller  62  may adjust the driving strength of each OLED  66  to compensate for shifts in color and/or brightness due to measured operating temperature of OLEDs  66 , temperature history of OLEDs  66 , usage history of OLEDs  66 , or combinations thereof. For example, the driving strengths may be adjusted to compensate for both a localized aging and an overall aging of OLEDs  66  across the display. In some embodiments, the controller  62  may make a driving strength adjustment to the differentially aged OLEDs  66  to make the emitted light substantially math other OLEDs  66  or a color and/or brightness target. Alternatively, the controller  62  may make a driving strength adjustment to other less aged OLEDs  66  or to surrounding OLEDs  66  to make a differentially aged OLED  66  less noticeable than before. As another alternative, the controller may make driving strength adjustments to both the more aged OLEDs  66  and the less aged OLEDs  66  to improve the overall viewability of the display. The controller  62  may employ AM, PWM, or other suitable techniques to vary the driving strength. 
     In some embodiments, each thermal sensor  55  may be disposed in the display  14  with more than one OLED  66 . In an embodiment illustrated in  FIG. 12 , thermal sensors  55  are disposed in zones  60  of the display  14  to measure the temperature of each zone  60 . Each zone  60  includes at least one thermal sensor  55  and at least one OLED  66  proximate to the thermal sensor  55 . For example, the temperature of each zone  60  across the display  14  may vary, affecting the appearance as discussed above. The thermal sensors  55  may transmit information in the form of an electrical signal in response to measured temperature to a controller  62 . 
     The zones  60  may be arranged in a grid or in a matrix over the plane of the display  14  as shown in  FIG. 12 , 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 possibly, more thermal sensors  55  than others areas. The number, size, and shape of zones  60  may affect the resolution of the temperature map  75 . For example, zones  60  over components  57  with localized heat sources may be sized smaller so that a more precise temperature map  75  may be measured. Components  57  with substantially uniform temperatures during use may have less zones  60  and possibly less thermal sensors  55 . Zones  60  may be defined as having a certain number of OLEDs  66  or as the OLEDs  66  closest to each thermal sensor  55 . 
     OLEDs  66  and thermal sensors  55  disposed in zones  60  across the display as illustrated in  FIG. 13 , may also have 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 thermal sensor  55 . In an embodiment as shown in  FIG. 13 , each zone  60  may include a sub array of pixels containing a number of red OLEDs  66 R, the same number of green OLEDs  66 G, the same number of blue OLEDs  66 B and the same number of white OLEDs  66 W. In such a configuration, the resolution of the temperature map  75  may be determined by dividing the overall display resolution by the number of zones  60 . In other embodiments, each zone  60  may include a different number or color set of OLEDs  66 . 
     The OLEDs  66 , thermal sensors  55 , drivers  64 , and controller  62  may function in substantially the same manner as described above with  FIG. 9 , except that the thermal sensors  55  are disposed with zones  60  of OLEDs  66  rather than with individual OLEDs. Thermal sensors  55  disposed with zones  60  measure the operating temperature of each zone  60 , and the controller  62  may generate a temperature map  75  based on these measured zone temperatures. In some embodiments, the controller  62  may make compensation adjustments to the OLEDs  66  within each zone  60  based on the temperature map  75 . Adjustments may include adjusting the driving strength of OLEDs  66  in each zone or changing the location of images to be shown on the display. In other embodiments, the controller  62  may adjust the operation of components  57  beneath zones  60  of the display  14 . In some embodiments, the controller  62  may adjust both the driving strengths of OLEDs  66  and the operation of components  57 . 
     As described above, the temperature map  75  generated from zone temperatures may be used to determine the temperature history for each zone  60  and the OLEDs  66  within each zone  60 . The controller  62  may also determine the aging for OLEDs  66  based on the temperature history and usage history for each zone  60  stored in memory  28 . In some embodiments, the controller  62  may adjust the driving strength of OLEDs  66  within each zone  60  based on the determined aging for each zone  60  or OLED  66 . In other embodiments, the controller  62  may make compensation adjustments to the OLEDs  66  within each zone  60  based on both the determined aging for each zone  60  or OLED  66  and the temperature map  75 . 
     Methods for operating the above described OLED displays  14  are illustrated in  FIGS. 14 and 15 . The method  100 , as illustrated in  FIG. 14 , may adjust components  57  or the image shown on the display  14  based on a temperature map  75  of present operating temperatures. The method  100  may be used with displays  14  having thermal sensors  55  disposed with OLEDs  66  in a 1:1 ratio across the display  14  or thermal sensors  55  disposed with zones  60  of OLEDs  66  across the display  14 . The thermal sensors  55  first measure (block  102 ) the temperature at each thermal sensor  55 . In some embodiments, this temperature may relate to the operating temperature of each respectively coupled OLED  66 . In other embodiments, this temperature relates to the operating temperature of a zone  60  of the display. The thermal sensors  55  transmit temperature information to the controller  62  to process the measured operating temperatures. 
     The controller  62  receives the temperature information from each thermal sensor  55  and creates (block  104 ) a temperature map  75  for the display  14 . The temperature map  75  may indicate the present operating temperature across the display  14 , identifying portions with increased temperatures and localized heat sources. For example, the temperatures may vary across the display  14  due to components  57  beneath the display  14  that warm more than other components  57 . As another example, the temperature map  75  may be non-uniform due to localized external heat sources. As discussed above, temperature may affect the color and/or brightness of light emitted by an OLED. The controller  62  may use the temperature map  75  to determine (block  106 ) which OLEDs  66  or zones  60  may be affected by a present operating temperature beyond a threshold temperature stored in memory  28 . OLEDs  66  operating at temperatures beyond a threshold may emit light of a noticeably different color and/or brightness than OLEDs  66  operating below the threshold temperature. 
     The controller  62  may then make adjustments (block  108 ) to compensate for the noticeably different color and/or brightness of light emitted from the OLEDs  66  operating beyond a threshold temperature. In some embodiments, the compensation may include adjusting the driving strength for each affected OLED  66  so that the properties of 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 temperature, present drive strength, previous drive strength adjustments, recorded operating hours, and information stored in memory  28  like calibration curves, algorithms, and charts. Based on these factors, the controller  62  may then adjust each OLED  66  for the operating temperature measured by the coupled thermal sensor  55 . Furthermore, in certain embodiments, the driving strengths may be adjusted to compensate for both a localized increased temperature and an overall increased temperature across the display  14 . Changes in brightness and/or color for each OLED  66  from these adjustments may improve the image quality of a display  14 . 
     In other embodiments, the controller  62  may make adjustments (block  108 ) to change the location that an image is shown on a display  14 . The image location may be changed to an area of the display with different temperature map characteristics, such as lower measured operating temperature. In some embodiments, images may be moved across the display  14  to minimize the total compensation made for OLEDs  66  of the display  14 . In other embodiments, images may be moved across the display  14  so that the image shown may substantially match the color and brightness of the target image. 
     In other embodiments, the controller  62  may determine that the OLEDs  66  operating beyond a threshold temperature and make adjustments (block  108 ) to lower the heat generated by components  57  beneath these OLEDs  66 . As current passes through components  57 , resistance heat warms the component  57 , which may warm the display  14  and other components  57 . The components  57  of an electronic device  10  may generate less heat if operations are slowed or otherwise changed. For example, a CPU  52  operating at 600 MHz may generate more heat than a CPU  52  operating at 400 MHz. As another example, the power of a transmitted signal from the RF transmitter  50  may be reduced so that the RF transmitter  50  generates less heat. In some embodiments, the controller  62  may adjust the operation of one or more components  57  at a time. Furthermore, in some embodiments the controller  62  may adjust the operation of one or more components  57  in addition to adjusting the drive strength of affected OLEDs  66 . 
     The method  220 , as illustrated in  FIG. 15 , may make adjustments to each OLED  66  or the image shown on the display  14  based at least in part on the temperature and usage history of each OLED  66 . The method  220  may be used with displays  14  as described above with  FIGS. 9 and 13  having thermal sensors  55  disposed with OLEDs  66  in a 1:1 ratio or in zones  60  across the display  14 . The thermal sensors  55  first measure (block  222 ) the temperature at each thermal sensor  55 . Thus, the measured temperature may relate directly to the operating temperature of proximate OLEDs  66 . The thermal sensors  55  transmit temperature information to the controller  62  to process the measured operating temperatures. 
     As discussed with the previous method  100 , the controller  62  receives the present operating temperature from each thermal sensor  55  and creates (block  224 ) a temperature map  75  for the display  14 . With this method  220 , the controller  62  additionally may determine (block  226 ) the temperature history and usage history of each OLED  66 . As discussed above, the temperature history may include the running average operating temperature of OLEDs  66 , the duration of operation above threshold temperatures, and the like. The controller  62  may also determine a usage history for each OLED  66  based on the recorded operating hours and driving strengths applied to the OLEDs  66 . Both the temperature history and usage history for each OLED  55  may be recorded in memory  28 . 
     Following the determination (block  226 ) of the temperature history and usage history for each OLED  66 , the controller  62  may then determine (block  228 ) the effect that the parameters operating temperature, temperature history, and usage history have on the emitted light from each OLED  66 . The controller  62  may determine the effect of these parameters on the color and/or brightness through comparison of these parameters with calibration curves, algorithms, or charts stored in memory  28 . 
     The controller  62  may then adjust (block  230 ) the driving strength of each OLED  66  to compensate for shifts in the color and brightness due to aging alone or aging and measured operating temperature of each OLED  66 . As discussed above, the controller  62  may adjust driving strengths to both localized portions of the display  14  or the display  14  as a whole based on any of the parameters. The controller  62  may also adjust the operation of components  57  beneath the display  14  based on the temperature history and usage history of OLEDs  66  across the display. 
     In other embodiments, the controller  62  may change the location that an image is shown on a display  14 . The image location may be changed to an area of the display with different aging characteristics, different operating temperature, or both. In some embodiments, images may be moved across the display  14  to minimize the total compensation needed for OLEDs  66  of the display  14 . In other embodiments, images may be moved across the display  14  so that the image shown may substantially match the color and brightness of the target image. 
     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: 20120531
Publication Date: 20151103
Grant Date: 20151103
Priority Date: 20120531
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": "G09G2320/048", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2330/045", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2300/0819", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/3225", "inventive": true, "first": true, "tree": "[]"}, {"code": "G09G2320/0233", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/041", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0295", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/029", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2300/04", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L27/3225", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2320/0233", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/3225", "inventive": true, "first": true, "tree": "[]"}, {"code": "G09G2320/0233", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2330/045", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2300/0819", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/029", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2300/0819", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/3225", "inventive": true, "first": true, "tree": "[]"}, {"code": "G09G2320/029", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/048", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2340/0464", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2330/045", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0295", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2300/04", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2340/0464", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2300/04", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/041", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/048", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/041", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0295", "inventive": false, "first": false, "tree": "[]"}, {"code": "H10K59/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10K59/65", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 48579504